Data transmitting device, and system and method for radio communication
Abstract
[Task] When transmitting confidential information to a specific wireless station via a wireless line, transmit the confidential information with high security.
Solution.The propagation environment estimation unit 101c estimates the radio propagation path environment shared only with the receiving station 102, which is the transmission target of the transmission data including the confidential information, and considers this wireless propagation path environment to transmit the transmission data including the confidential information. To send. As a result, the confidential information cannot be received or restored by other wireless stations having different radio propagation path environments, so that the confidential information can be transmitted with high security.

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Projected expiry passed 28 August 2021, 5.1 years ago.
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36 claims: 9 independent, 27 dependent
- 1【特許請求の範囲】 【請求項1】 秘匿情報を含む送信データを無線により無線局に伝送するデータ伝送装置であって、 前記無線局により発信された信号を受信する受信手段と、 前記受信手段により得られた受信信号に基づいて前記無線局との間の無線伝搬路環境を推定する推定手段と、 前記推定手段により得られた無線伝搬路環境を考慮して、前記秘匿情報を含む送信データを前記無線局に送信する送信手段とを具備するデータ伝送装置。
- 2【請求項2】 前記推定手段は、前記受信信号に基づいて前記無線局との間の信号伝搬時間を前記無線伝搬環境として推定し、 前記送信手段は、前記送信データが所望の受信時刻に前記無線局に到達するように、前記信号伝搬時間を考慮したタイミングで、前記送信データを送信する請求項1に記載のデータ伝送装置。
- 3【請求項3】 前記秘匿情報を含む送信データ中の、前記無線局との間で予め決められた位置に、擬似シンボルを付加する擬似シンボル付加手段を具備し、 前記送信手段は、擬似シンボルが付加された送信データを前記無線局に送信する請求項2に記載のデータ伝送装置。
- 4【請求項4】 前記秘匿情報を含む送信データ中の、前記無線局との間で予め決められた位置に、互いに同期関係にある同期系列信号を付加する同期信号付加手段と、 前記同期系列信号についての擬似同期信号であり、互いに同期関係にある擬似同期系列信号を付加する擬似同期信号付加手段とを具備する請求項2又は請求項3に記載のデータ伝送装置。
- 5【請求項5】 秘匿情報を含む送信データを無線により無線局に伝送するデータ伝送装置であって、 互いに異なる位置に配置され、前記無線局により発信された信号を受信する第1及び第2の受信手段と、 前記第1の受信手段により得られた受信信号に基づいて当該第1の受信手段と前記無線局との間の第1の無線伝搬路環境を推定すると共に、前記第2の受信手段により得られた受信信号に基づいて当該第2の受信手段と前記無線局との間の第2の無線伝搬路環境を推定する推定手段と、 それぞれ前記第1及び第2の受信手段と同じ位置に配置され、前記推定手段により得られた前記第1及び第2の無線伝搬路環境を考慮して、前記秘匿情報を含む送信データを前記無線局に送信する第1及び第2の送信手段とを具備するデータ伝送装置。
- 6【請求項6】 前記推定手段は、前記各受信信号に基づいて、前記無線局と前記第1の受信手段との間の第1の無線伝搬路における信号伝搬時間及び前記無線局と前記第2の受信手段との間の第2の無線伝搬路における信号伝搬時間を前記第1及び第2の無線伝搬環境として推定し、 前記第1及び第2の送信手段は、前記送信データが予め前記無線局との間で設定された時刻に前記無線局に到達するように、前記各信号伝搬時間を考慮したタイミングで、前記送信データを前記無線局に送信する請求項5に記載のデータ伝送装置。
- 7【請求項7】 前記第1及び第2の送信手段は、第1及び第2の送信データがそれぞれ異なる時刻に前記無線局に到達するタイミングで各送信データを送信する請求項6に記載のデータ伝送装置。
- 8【請求項8】 前記第1及び第2の送信データは、互いに同一のフォーマットで形成されており、 前記第1及び第2の送信手段は、第1及び第2の送信データが同時刻に前記無線局に到達するタイミングで各送信データを送信する請求項6に記載のデータ伝送装置。
- 9【請求項9】 前記秘匿情報を含む送信データ中の、前記無線局との間で予め決められた位置に、擬似シンボルを付加する擬似シンボル付加手段を具備し、 前記送信手段は、擬似シンボルが付加された送信データを前記無線局に送信する請求項6から請求項8のいずれかに記載のデータ伝送装置。
- 10【請求項10】 前記秘匿情報を含む送信データ中の、前記無線局との間で予め決められた位置に、互いに同期関係にある同期系列信号を付加する同期信号付加手段と、 前記同期系列信号についての擬似同期信号であり、互いに同期関係にある擬似同期系列信号を付加する擬似同期信号付加手段とを具備する請求項6から請求項9のいずれかに記載のデータ伝送装置。
- 11【請求項11】 前記第1及び第2の送信データの単位通信フレームを並べたときに、前記秘匿情報を形成する秘匿シンボル同士が重ならないように、前記第1及び第2の各送信データ中に、秘匿シンボルに対して電力が非常に小さい擬似シンボルを付加する擬似シンボル付加手段を具備し、 前記第1及び第2の送信手段は、第1及び第2の送信データが同時刻に前記無線局に到達するタイミングで各送信データを送信する請求項6に記載のデータ伝送装置。
- 12【請求項12】 前記推定手段は、前記信号伝搬時間に加えて、前記無線局と前記第1の受信手段との間の第1の無線伝搬路における信号電力減衰量、及び、前記無線局と前記第2の受信手段との間の第2の無線伝搬路における信号電力減衰量を推定し、 前記第1及び第2の送信手段は、それぞれ前記第1及び第2の無線伝搬路における信号電力減衰量を考慮した送信電力で、前記秘匿情報を含む送信データを前記無線局に送信する請求項6に記載のデータ伝送装置。
- 13【請求項13】 前記第1及び第2の送信データは、互いに同一のフォーマットで形成されており、 前記第1及び第2の送信手段は、第1及び第2の送信データが同時刻に前記無線局に到達するタイミングで各送信データを送信すると共に、前記信号電力減衰量に基づいて、前記無線局が各送信データを合成受信した際に復調し得る最低レベルに近い送信電力で前記送信データを送信する請求項12に記載のデータ伝送装置。
- 14【請求項14】 前記推定手段は、前記受信手段により得られた受信信号に基づいて受信波の偏波面を検出することにより前記無線伝搬路環境を推定し、 前記送信手段は、前記推定手段によって検出された前記偏波面と同じ偏波面を有する送信波により、前記秘匿情報を含む送信データを前記無線局に送信する請求項1に記載のデータ伝送装置。
- 15【請求項15】 前記送信手段は、前記受信手段により得られた受信信号に基づいて受信波の偏波面を検出することにより前記無線伝搬路環境を推定し、 前記送信手段は、前記推定手段によって検出された前記偏波面と同じ偏波面を有する送信波に前記秘匿情報を含む送信データを重畳して送信すると共に、前記推定手段によって検出された前記偏波面に直交する偏波面を有する送信波に擬似データを重畳して送信する請求項1に記載のデータ伝送装置。
- 16【請求項16】 前記推定手段は、前記受信手段により得られた受信信号に基づいて受信波の偏波面を検出することにより前記無線伝搬路環境を推定し、 前記送信手段は、前記推定手段によって検出された前記偏波面に対して、前記無線局の間で予め決められた量だけ前記偏波面を回転させた送信波により、前記秘匿情報を含む送信データを前記無線局に送信する請求項1に記載のデータ伝送装置。
- 17【請求項17】 前記推定手段は、さらに、前記受信信号の到来方向を推定し、 前記送信手段は、前記到来方向を考慮した方向に前記秘匿情報を含む送信データを送信する請求項2から請求項16のいずれかに記載のデータ伝送装置。
- 18【請求項18】 前記送信手段は、前記推定手段により推定された到来方向に基づいて、前記秘匿情報を含む送信データを前記無線局の方向に向けて送信すると共に、擬似データを前記無線局とは異なる方向に向けて送信する請求項17に記載のデータ伝送装置。
- 19【請求項19】 前記送信手段は、アダプティブアレーアンテナを有し、前記秘匿情報を含む送信データを送信する際には、前記到来方向に指向性が向くように各アレーアンテナを重み付けすると共に、前記擬似データを送信する際には、前記到来方向以外の方向に指向性が向くように各アレーアンテナを重み付けする請求項18に記載のデータ伝送装置。
- 20【請求項20】 所定の拡散符号を使って前記秘匿情報を拡散処理し、これにより得た第1の拡散信号を前記第1の送信手段に供給する第1の拡散手段と、前記拡散符号とは異なる拡散符号を使ってかつ前記第1の拡散手段による拡散ゲインと同程度の拡散ゲインが得られるように擬似情報を拡散処理し、これにより得た第2の拡散信号を前記第2の送信手段に供給する第2の拡散手段とを具備し、 前記第1及び第2の送信手段は、前記推定手段により推定された信号電力減衰量に基づき、前記第1及び第2の拡散信号が前記無線局に到達したときに、前記第1の拡散信号の受信電力値と前記第2の拡散信号の受信電力値に一定以上の差が生じるように送信電力を制御する請求項12に記載のデータ伝送装置。
- 21【請求項21】 所定の拡散符号を使って前記秘匿情報を拡散処理することにより第1の拡散信号を形成する第1の拡散手段と、前記拡散符号とは異なる拡散符号を使ってかつ前記第1の拡散手段による拡散ゲインと同程度の拡散ゲインが得られるように擬似情報を拡散処理することにより第2の拡散信号を形成する第2の拡散手段とを具備し、 前記第1及び第2の送信手段は、前記推定手段により推定された到来方向に基づいて、前記第1の拡散信号の受信電力値と前記第2の拡散信号の受信電力値に一定以上の差が生じる方向に、前記第1及び第2の拡散信号を送信する請求項18に記載のデータ伝送装置。
- 22【請求項22】 前記秘匿情報を含む送信データを、前記無線局との間で予め決められた順序で並べ換えるデータ並べ換え手段を具備し、 前記送信手段は、当該データ並べ換え手段により並べ換えられた送信データを前記無線局に送信する請求項2から請求項21のいずれかに記載のデータ伝送装置。
- 23【請求項23】 秘匿情報を含む送信データを第1の無線局から第2の無線局に無線により送信する無線通信システムであって、 前記第1の無線局は、前記第2の無線局により発信された信号を受信する受信手段と、前記受信手段により得られた受信信号に基づいて前記無線局との間の信号伝搬時間を推定する推定手段と、前記送信データが所望の受信時刻に前記無線局に到達するように、前記信号伝搬時間を考慮したタイミングで、前記送信データを送信する送信手段とを具備し、 前記第2の無線局は、前記第1の無線局に前記信号伝搬時間を推定するための信号を送信する送信手段と、前記秘匿情報を含む送信データを受信して復調する受信手段と、前記第1の無線局との間で予め設定した受信時刻に同期するように当該受信手段の受信復調動作を制御する受信制御手段とを具備する無線通信システム。
- 24【請求項24】 前記第1の無線局は、前記秘匿情報を含む送信データ中の、前記無線局との間で予め決められた位置に、互いに同期関係にある同期系列信号を付加すると共に、前記同期系列信号についての擬似同期信号であり互いに同期関係にある擬似同期系列信号を付加し、 前記第2の無線局は、前記予め設定した受信時刻を基準にして前記同期系列信号を抽出し、当該同期系列信号に基づいて、受信した前記秘匿情報を含む送信データを補正する請求項23に記載の無線通信システム。
- 25【請求項25】 前記第1の無線局は、前記第2の無線局との間で予め設定した前記受信時刻から所定時間だけずれた時刻に前記送信データが到達するタイミングで前記送信データを送信し、 前記第2の無線局は、所定時間ずれて到達する前記送信データに対して前記同期系列信号を用いて同期処理を行って前記送信データを復調する請求項24に記載の無線通信システム。
- 26【請求項26】 前記第1の無線局は、前記所定時間のずれ量に関連付けて前記秘匿情報を送信し、 前記第2の無線局は、前記所定時間のずれ量を前記秘匿情報についての認識情報として用いて復調処理を行う請求項25に記載の無線通信システム。
- 27【請求項27】 前記第2の無線局は、 前記受信時刻を基準にして所定の探索範囲を設定する探索範囲設定手段と、 前記探索範囲設定手段により設定した範囲内で前記受信信号のピークを探索することにより前記同期系列信号を抽出する同期信号抽出手段と、 抽出された同期系列信号に基づいて、受信した前記秘匿情報を含む送信データを補正する補正手段とを具備する請求項24に記載の無線通信システム。
- 28【請求項28】 秘匿情報を含む送信データを第1の無線局から第2の無線局に無線により送信する無線通信システムであって、 前記第1の無線局は、前記第2の無線局により発信された信号を受信する受信手段と、前記受信手段により得られた受信信号に基づいて受信波の偏波面を検出する偏波面検出手段と、検出された偏波面に対して、前記第1及び第2の無線局間で予め決められた量だけ前記偏波面を回転させた送信波により、前記秘匿情報を含む送信データを前記第2の無線局に送信する送信手段とを具備し、 前記第2の無線局は、前記第1の無線局に前記偏波面検出用の信号を出力すると共に前記第1の無線局が送信した前記秘匿情報を含む送信データを受信するアンテナの偏波面特性を、前記偏波面検出用の信号を出力してから前記秘匿情報を含む送信データを受信する迄の間に、前記第1及び第2の無線局間で予め決められた量だけ回転させる無線通信システム。
- 29【請求項29】 前記第1及び第2の無線局は、前記第1及び第2の無線局間で予め決められた量だけ偏波面を回転させる処理を、前記第1及び第2の無線局間で予め決められた間隔で繰り返して行う請求項28に記載の無線通信システム。
- 30【請求項30】 秘匿情報を含む送信データを第1の無線局から第2の無線局に無線により送信する無線通信システムであって、 前記第1の無線局は、前記第2の無線局から発信された信号に基づいて無線伝搬時間及び信号電力減衰量を推定する推定手段と、所定の拡散符号を使って前記秘匿情報を拡散処理することにより第1の拡散信号を形成すると共に、前記拡散符号とは異なる拡散符号を使ってかつ前記第1の拡散信号の拡散ゲインと同程度の拡散ゲインが得られるように擬似情報を拡散処理することにより第2の拡散信号を形成する拡散手段と、前記推定手段により推定された信号電力減衰量に基づき、前記第1及び第2の拡散信号が前記第2の無線局に到達したときに、前記第1の拡散信号の受信電力値と前記第2の拡散信号の受信電力値に一定以上の差が生じるように送信電力を制御して前記第1及び第2の拡散信号を送信する送信手段とを具備し、 前記第2の無線局は、前記第1及び第2の拡散信号を逆拡散する逆拡散手段と、逆拡散された信号の信号レベルに基づいて前記秘匿情報を抽出する秘匿情報抽出手段とを具備する無線通信システム。
- 31【請求項31】 秘匿情報を含む送信データを第1の無線局から第2の無線局に無線により送信する無線通信システムであって、 前記第1の無線局は、前記第2の無線局から発信された信号に基づいて無線伝搬時間及び信号到来方向を推定する推定手段と、所定の拡散符号を使って前記秘匿情報を拡散処理することにより第1の拡散信号を形成すると共に、前記拡散符号とは異なる拡散符号を使ってかつ前記第1の拡散信号の拡散ゲインと同程度の拡散ゲインが得られるように擬似情報を拡散処理することにより第2の拡散信号を形成する拡散手段と、前記推定手段により推定された到来方向に基づき、前記第1及び第2の拡散信号が前記第2の無線局に到達したときに、前記第1の拡散信号の受信電力値と前記第2の拡散信号の受信電力値に一定以上の差が生じる方向に前記第1及び第2の拡散信号を送信する送信手段とを具備し、 前記第2の無線局は、前記第1及び第2の拡散信号を逆拡散する逆拡散手段と、逆拡散された信号の信号レベルに基づいて前記秘匿情報を抽出する秘匿情報抽出手段とを具備する無線通信システム。
- 32【請求項32】 秘匿情報を含む送信データを第1及び第2の無線局から第3の無線局に無線により送信する無線通信システムであって、 前記第1及び第2の無線局はそれぞれ、有線ネットワークに接続され当該ネットワークから前記秘匿情報を取得するためのネットワーク接続手段と、前記第3の無線局により発信された信号を受信する受信手段と、前記受信手段により得られた受信信号に基づいて前記第3の無線局との間の信号伝搬時間を推定する推定手段と、前記送信データが所望の受信時刻に前記第3の無線局に到達するように、前記信号伝搬時間を考慮したタイミングで、前記送信データを送信する送信手段とを具備し、 前記第3の無線局は、前記第1の無線局に前記信号伝搬時間を推定するための信号を送信する送信手段と、前記秘匿情報を含む送信データを受信して復調する受信手段と、前記第1及び第2の無線局との間で予め設定した受信時刻に同期するように当該受信手段の受信復調動作を制御する受信制御手段とを具備する無線通信システム。
- 33【請求項33】 秘匿情報を含む送信データを第1の無線局から第2の無線局に無線により送信する無線通信方法であって、 前記第2の無線局から前記第1の無線局に信号を送信し、 前記第1の無線局が、受信した信号に基づいて前記第1及び第2の無線局間での信号伝搬時間を推定し、 前記第1の無線局は、前記送信データが所望の受信時刻に前記無線局に到達するように、前記信号伝搬時間を考慮したタイミングで、前記秘匿情報を含む送信データを送信する無線通信方法。
- 34【請求項34】 前記所望の受信時刻は、前記第1の無線局から前記秘匿情報を含む送信データを送信する前に、前記第1及び第2の無線局との間で少なくとも1往復分の信号の送受信を行うことにより推定した前記信号伝搬時間に基づいて前記第1及び第2の無線局間で設定されたものである請求項33に記載の無線通信方法。
- 35【請求項35】 前記秘匿情報を含む送信データ中の、前記無線局との間で予め決められた位置には擬似シンボルが付加されている 請求項33又は請求項34に記載の無線通信方法。
- 36【請求項36】 前記秘匿情報を含む送信データ中の、前記無線局との間で予め決められた位置には互いに同期関係にある同期系列信号が付加されていると共に、互いに同期関係にある擬似同期系列信号が付加されている請求項33又は請求項34に記載の無線通信方法。
Independent claims36
885 paragraphs in 1 section, as filed
Description: TECHNICAL FIELD [Detailed description of the invention]
【0001】
[Technical field to which the invention belongs]
The present invention relates to a data transmission device, a wireless communication system and a wireless communication method, and is particularly suitable for application when transmitting confidential information to a specific wireless station via a wireless line.
【0002】
[Conventional technology]
In recent years, digital wireless communication has come to occupy an important position in the communication field due to dramatic improvements in transmission speed and transmission quality. On the other hand, since wireless communication uses the radio wave space, which is a public good, there is a fundamental drawback that reception by a third party is possible from the viewpoint of confidentiality. That is, there is always a risk that the communication content will be intercepted by a third party and information will be leaked.
【0003】
Therefore, in the conventional wireless communication, the confidential information is encrypted so that even if the transmitted data is intercepted by a third party, the content of the confidential information cannot be understood by the third party. Cryptography has been studied in various fields and applied in various fields. This is because encryption has the advantage that a certain level of security can be ensured without changing the wireless communication system.
【0004】
[Problems to be Solved by the Invention]
However, in information encryption, there is a problem that information can be decrypted relatively easily if the code for encryption and the encryption procedure are known. Especially in the current situation where high-speed computers are generally widespread, security cannot be ensured unless a fairly complicated encryption process is performed.
【0005】
Especially in arithmetic encryption, in order to decrypt the encrypted information, an encryption key which is common information of encryption and decryption is required. When it is necessary to give and receive this encryption key, if the encryption key is intercepted by a third party, there is always a risk that the confidential information can be easily deciphered from the encryption key and the secret text. In particular, when the encryption key or the encrypted information is transmitted via the wireless line as described above, the risk is further increased.
【0006】
The present invention has been made in view of this point, and is a data transmission device, a wireless communication system, and a wireless system capable of transmitting confidential information with high security when transmitting confidential information to a specific wireless station via a wireless line. The purpose is to provide a communication method.
【0007】
[Means for solving problems]
In order to solve such a problem, the data transmission device of the present invention is a data transmission device that wirelessly transmits transmission data including confidential information to a radio station, and is a receiving means for receiving a signal transmitted by the radio station and receiving. In consideration of the estimation means that estimates the radio propagation path environment with the radio station based on the received signal obtained by the means and the radio propagation path environment obtained by the estimation means, the transmission data including the confidential information is wirelessly transmitted. A configuration including a transmission means for transmitting to a station is adopted.
【0008】
According to this configuration, a radio propagation path environment shared only with a radio station to which transmission data including confidential information is transmitted is estimated by an estimation means, and transmission including confidential information is transmitted in consideration of this wireless propagation path environment. Since data is transmitted, confidential information cannot be received or restored by other radio stations having different radio propagation path environments. As a result, confidential information can be transmitted with high security.
【0009】
Further, in the data transmission device of the present invention, the estimation means estimates the signal propagation time with the radio station as the radio propagation environment based on the received signal, and the transmission means sends the transmission data to the radio station at a desired reception time. A configuration is adopted in which transmission data is transmitted at a timing that takes into consideration the signal propagation time so that the signal can be reached.
【0010】
According to this configuration, in the radio station to which the confidential information is transmitted, the transmission data including the confidential information arrives at a predetermined reception time. Therefore, the confidential information is demodulated in synchronization with that time. Can be restored. On the other hand, the confidential information cannot be restored by a wireless station other than the wireless station to which the confidential information is transmitted. This is because the reference time information indicating the reception and demodulation start time is determined based on the signal propagation time shared only between the data transmission device and the radio station to be transmitted, so that other radio stations receive and demodulate. This is because the reference time indicating the start time cannot be known. As a result, other radio stations cannot recover the confidential information, and security is ensured.
【0011】
Further, the data transmission device of the present invention includes a pseudo-symbol adding means for adding a pseudo-symbol at a position predetermined with a radio station in transmission data including confidential information, and the transmitting means has a pseudo-symbol. A configuration is adopted in which the added transmission data is transmitted to a radio station.
【0012】
According to this configuration, since the radio station to which the confidential information is transmitted knows the position of the pseudo symbol, it is possible to easily extract the confidential information by removing only the pseudo symbol after receiving and demodulating the transmitted data. On the other hand, even if the transmitted data can be demodulated by other radio stations, the confidential information cannot be extracted due to the existence of the pseudo symbol. As a result, security is further improved.
【0013】
Further, the data transmission device of the present invention includes a synchronization signal adding means for adding a synchronization sequence signal having a synchronization relationship with each other at a predetermined position with a radio station in transmission data including confidential information, and a synchronization sequence. It is a pseudo-synchronous signal for a signal, and adopts a configuration including a pseudo-synchronous signal adding means for adding pseudo-synchronous sequence signals having a synchronous relationship with each other.
【0014】
According to this configuration, the radio station to which the confidential information is transmitted knows the position of the synchronization signal, so that the synchronization signal can be easily extracted. The radio station will be able to perform time synchronization, phase fluctuation detection, gain fluctuation detection, etc. using the extracted synchronization signal. As a result, the reception quality can be improved. On the other hand, in other radio stations, the confidential information cannot be restored, and the pseudo-synchronization signal and the synchronization signal cannot be distinguished. Thus, it is possible to obtain a data transmission device having high security and capable of improving reception quality in a radio station.
【0015】
Further, the data transmission device of the present invention is a data transmission device that wirelessly transmits transmission data including confidential information to a radio station, and is arranged at different positions from each other to receive signals transmitted by the radio station. Based on the second receiving means and the received signal obtained by the first receiving means, the first radio propagation path environment between the first receiving means and the radio station is estimated, and the second receiving means is used. The estimation means for estimating the second radio propagation path environment between the second receiving means and the radio station based on the received signal obtained by the above, and the estimation means are arranged at the same positions as the first and second receiving means, respectively. In consideration of the first and second radio propagation path environments obtained by the estimation means, a configuration including first and second transmission means for transmitting transmission data including confidential information to the radio station is adopted.
【0016】
According to this configuration, a plurality of radio propagation path environments shared only with a radio station to which transmission data including confidential information is transmitted are estimated by an estimation means, and concealment is performed in consideration of the plurality of radio propagation path environments. Since transmission data including information is transmitted, confidential information cannot be received or restored by other radio stations having different radio propagation path environments. Further, when another radio station tries to intercept the confidential information, it is necessary to estimate a plurality of radio propagation environments, which is more difficult than estimating one radio propagation environment. As a result, confidential information can be transmitted with higher security.
【0017】
Further, in the data transmission device of the present invention, the estimation means is based on each received signal, the signal propagation time in the first radio propagation path between the radio station and the first receiving means, and the radio station and the second reception. The signal propagation time in the second radio propagation path to and from the means is estimated as the first and second radio propagation environments, and in the first and second transmission means, the transmission data is set in advance with the radio station. A configuration is adopted in which transmission data is transmitted to the radio station at a timing that considers each signal propagation time so that the signal reaches the radio station at the specified time.
【0018】
According to this configuration, in the radio station to which the confidential information is transmitted, the transmission data including the confidential information arrives at a predetermined reception time. Therefore, the confidential information is demodulated in synchronization with that time. Can be restored. On the other hand, the confidential information cannot be restored by a wireless station other than the wireless station to which the confidential information is transmitted. This is because the reference time information indicating the reception and demodulation start times is determined based on a plurality of signal propagation times shared only between the data transmission device and the radio station to be transmitted. This is because it is not possible to know the reference time indicating the reception and demodulation start times. As a result, other radio stations cannot recover the confidential information, and security is ensured.
【0019】
Further, the data transmission device of the present invention adopts a configuration in which the first and second transmission means transmit each transmission data at the timing when the first and second transmission data arrive at the radio station at different times.
【0020】
According to this configuration, other radio stations that are not the target of transmitting the confidential information must estimate different arrival times when they try to intercept the confidential information. However, since this arrival time is a time that only the radio station to which the confidential information is transmitted can know, other wireless stations cannot restore the confidential information. As a result, for example, if the confidential information is divided and distributed to the first and second transmission means and arrives at the radio station at the above different times, it becomes more difficult for the other radio stations to restore the confidential information.
【0021】
Further, in the data transmission device of the present invention, the first and second transmission data are formed in the same format as each other, and in the first and second transmission means, the first and second transmission data are at the same time. A configuration is adopted in which each transmission data is transmitted at the timing of reaching the radio station.
【0022】
According to this configuration, in the radio station to which the confidential information is transmitted, the received signal level is increased by synthesizing the transmission data in the same format at the time of reception. As a result, high-quality confidential information can be obtained. On the other hand, in other radio stations, the signal is deteriorated by interfering with each other at the time of reception. As a result, it becomes more difficult to obtain confidential information.
【0023】
Further, the data transmission device of the present invention includes a pseudo-symbol adding means for adding a pseudo-symbol at a position predetermined with a radio station in transmission data including confidential information, and the transmitting means has a pseudo-symbol. A configuration is adopted in which the added transmission data is transmitted to a radio station.
【0024】
According to this configuration, since the radio station to which the confidential information is transmitted knows the position of the pseudo symbol, it is possible to easily extract the confidential information by removing only the pseudo symbol after receiving and demodulating the transmitted data. On the other hand, even if the transmitted data can be demodulated by other radio stations, the confidential information cannot be extracted due to the existence of the pseudo symbol. As a result, security is further improved.
【0025】
Further, the data transmission device of the present invention includes a synchronization signal adding means for adding a synchronization sequence signal having a synchronization relationship with each other at a predetermined position with a radio station in transmission data including confidential information, and a synchronization sequence. It is a pseudo-synchronous signal for a signal, and adopts a configuration including a pseudo-synchronous signal adding means for adding pseudo-synchronous sequence signals having a synchronous relationship with each other.
【0026】
According to this configuration, the radio station to which the confidential information is transmitted knows the position of the synchronization signal, so that the synchronization signal can be easily extracted. The radio station will be able to perform time synchronization, phase fluctuation detection, gain fluctuation detection, etc. using the extracted synchronization signal. As a result, the reception quality can be improved. On the other hand, in other radio stations, the confidential information cannot be restored, and the pseudo-synchronization signal and the synchronization signal cannot be distinguished. Thus, it is possible to obtain a data transmission device having high security and capable of improving reception quality in a radio station.
【0027】
Further, in the data transmission device of the present invention, when the unit communication frames of the first and second transmission data are arranged, the first and second transmission data are prevented so that the concealed symbols forming the concealed information do not overlap each other. A pseudo-symbol addition means for adding a pseudo-symbol having a very low power to the secret symbol is provided therein, and the first and second transmission means send the first and second transmission data to the radio station at the same time. A configuration is adopted in which each transmission data is transmitted at the timing of arrival.
【0028】
According to this configuration, in the radio station to which the confidential information is transmitted, when the first and second transmission data are received at the same time, the confidential symbols do not interfere with each other, so that the confidential information is in a high quality state. Can be received at. On the other hand, other radio stations cannot receive the first and second transmission data at the same time, so that the secret information deteriorates due to the interference of the secret symbols. Moreover, since the pseudo symbol is added, the confidential information cannot be extracted.
【0029】
Further, in the data transmission device of the present invention, in addition to the signal propagation time, the estimation means includes the signal power attenuation in the first radio propagation path between the radio station and the first receiving means, and the radio station and the first. The signal power attenuation in the second radio propagation path between the two receiving means is estimated, and the first and second transmitting means consider the signal power attenuation in the first and second radio propagation paths, respectively. A configuration is adopted in which transmission data including confidential information is transmitted to a radio station using the transmitted power.
【0030】
According to this configuration, the radio station to which the confidential information is transmitted is optimally adapted to the first and second radio propagation paths at the reception level from the first and second transmission means, and is suitable for the reception operation. Synchronized transmission data can be obtained. As a result, the radio station to which the confidential information is transmitted can reliably restore the confidential information. On the other hand, other radio stations receive the transmission data from the data transmission device at a place different from the radio station to which the confidential information is transmitted, so that the reception level appropriate for demodulating the signal and the appropriate reception Since it becomes difficult to obtain the timing, it becomes difficult to restore the confidential information.
【0031】
Further, in the data transmission device of the present invention, the first and second transmission data are formed in the same format as each other, and in the first and second transmission means, the first and second transmission data are at the same time. Each transmission data is transmitted at the timing when it reaches the radio station, and the transmission data is transmitted with a transmission power close to the lowest level that can be demodulated when the radio station synthesizes and receives each transmission data based on the signal power attenuation amount. Take the configuration to do.
【0032】
According to this configuration, the radio station to which the confidential information is transmitted can synthesize and receive the same symbols of the first and second transmission data, so that a signal level sufficient for demodulation can be obtained. On the other hand, other receiving stations located in a place different from the radio station to which the confidential information is transmitted cannot obtain the signal level required for demodulation. As a result, the radio station to which the confidential information is transmitted can obtain high-quality confidential information, whereas other wireless stations cannot obtain the confidential information.
【0033】
Further, in the data transmission device of the present invention, the estimation means estimates the radio propagation path environment by detecting the polarization plane of the received wave based on the received signal obtained by the receiving means, and the transmitting means detects by the estimating means. A configuration is adopted in which transmission data including confidential information is transmitted to a radio station by a transmission wave having the same plane of polarization as the plane of polarization.
【0034】
According to this configuration, since the transmitting wave is controlled so that the transmitting means is the same as the polarization plane of the radio station, stable communication can be performed without adjusting the polarization planes of the transmitting side and the receiving side. As a result, the radio station to which the confidential information is transmitted can receive the transmission data including the confidential information transmitted from the transmitting means in a state where the rotation phase of the plane of polarization is optimal. As a result, the radio station can obtain high-quality confidential information. On the other hand, in other radio stations located in a place different from the radio station to which the secret information is transmitted, the propagation path environment is different, so that the antenna radiation characteristics are optimally set for the polarization plane of the transmission data including the secret information. Since it cannot be matched, the reception quality deteriorates and it becomes more difficult to restore the confidential information.
【0035】
Further, in the data transmission device of the present invention, the transmitting means estimates the radio propagation path environment by detecting the polarization plane of the received wave based on the received signal obtained by the receiving means, and the transmitting means detects by the estimating means. Transmission data containing confidential information is superimposed and transmitted on a transmission wave having the same polarization plane as the polarization plane, and pseudo data is superimposed on a transmission wave having a polarization plane orthogonal to the polarization plane detected by the estimation means. And send it.
【0036】
According to this configuration, in the radio station to which the confidential information is transmitted, the confidential information is normally received due to the characteristics of the antenna, but the pseudo information is not received. As a result, only confidential information can be easily extracted without using a complicated configuration. On the other hand, in other radio stations, confidential information and pseudo data are mixed and received. In the worst case, only pseudo data is received. As a result, the confidential information cannot be restored.
【0037】
Further, in the data transmission device of the present invention, the estimation means estimates the radio propagation path environment by detecting the polarization plane of the received wave based on the received signal obtained by the receiving means, and the transmitting means detects by the estimating means. A configuration is adopted in which transmission data including confidential information is transmitted to a radio station by a transmission wave in which the plane of polarization is rotated by a predetermined amount between the radio stations with respect to the plane of polarization.
【0038】
According to this configuration, a radio station that is not the target of transmission of confidential information cannot know the rotation information of the plane of polarization determined in advance between the data transmission device and the radio station that is the target of transmission of confidential information. This makes it more difficult to estimate the plane of polarization of the transmitted data including the confidential information transmitted by the transmitting means. As a result, the security of confidential information can be further improved.
【0039】
Further, in the data transmission device of the present invention, the estimation means further estimates the arrival direction of the received signal, and the transmission means includes transmission data including confidential information in a direction considering the arrival direction based on the estimation result by the estimation means. Is configured to send.
【0040】
According to this configuration, as a propagation path environment that can be shared only between the data transmission device and the radio station to which the confidential information is transmitted, by adding the direction of arrival of the signal, the confidential information to other wireless stations can be further transmitted. The risk of leakage is reduced.
【0041】
Further, in the data transmission device of the present invention, the transmission means transmits transmission data including confidential information toward the radio station based on the arrival direction estimated by the estimation means, and the pseudo data is transmitted to the radio station. The configuration is such that the data is transmitted in different directions.
【0042】
According to this configuration, in other radio stations, it becomes more difficult to restore the confidential information due to the reception of the pseudo data.
【0043】
Further, in the data transmission device of the present invention, the transmission means has an adaptive array antenna, and when transmitting transmission data including confidential information, each array antenna is weighted so that the directivity is directed in the arrival direction, and at the same time, each array antenna is weighted. When transmitting pseudo data, each array antenna is weighted so that the directivity faces in a direction other than the arrival direction.
【0044】
According to this configuration, by using the adaptive array antenna, it is possible to direct the directivity in the estimated arrival direction with high accuracy and high speed.
【0045】
Further, the data transmission device of the present invention has a first spreading means for spreading confidential information using a predetermined spreading code and supplying the first spreading signal obtained thereby to the first transmitting means, and a spreading code. Pseudo-information is diffused so that a diffusion gain similar to that obtained by the first diffusion means is obtained by using a diffusion code different from that of the first diffusion means, and the second diffusion signal obtained thereby is used as the second transmission means. The first and second transmitting means are provided with a second spreading means to supply to the radio station when the first and second spreading signals reach the radio station based on the signal power attenuation estimated by the estimating means. In addition, a configuration is adopted in which the transmission power is controlled so that a difference of a certain value or more occurs between the reception power value of the first diffusion signal and the reception power value of the second diffusion signal.
【0046】
According to this configuration, the first diffusion signal and the second diffusion signal reach the radio station to be transmitted without interfering with each other. Then, in the radio station, when the spread secret information and the spread pseudo information are back-spread, a difference of a certain amount or more occurs between the signal level of the secret information and the signal level of the pseudo information. As a result, the radio station can select the secret information and the pseudo information by discriminating the signal level and obtain the secret information. On the other hand, in other radio stations located at locations different from the above radio stations, the radio propagation paths are different, so that the signal level difference between the confidential information and the pseudo information after despreading is not regular. As a result, it is not possible to obtain the confidential information by selecting the confidential information and the pseudo information, and it becomes more difficult to restore the confidential information.
【0047】
Further, the data transmission device of the present invention uses a first spreading means for forming a first spreading signal by spreading processing confidential information using a predetermined spreading code, and a spreading code different from the spreading code. It is provided with a second spreading means for forming a second spreading signal by spreading pseudo information so that a spreading gain similar to that of the first spreading means can be obtained, and the first and second spreading means are provided. The transmission means are the first and the second in the direction in which the received power value of the first diffusion signal and the reception power value of the second diffusion signal differ by a certain amount or more based on the arrival direction estimated by the estimation means. The configuration is such that the diffusion signal of is transmitted.
【0048】
According to this configuration, the first diffusion signal and the second diffusion signal reach the radio station to be transmitted without interfering with each other. Then, in the radio station, when the spread secret information and the spread pseudo information are back-spread, a difference of a certain amount or more occurs between the signal level of the secret information and the signal level of the pseudo information. As a result, the radio station can select the secret information and the pseudo information by discriminating the signal level and obtain the secret information. On the other hand, in other radio stations located at locations different from the above radio stations, the radio propagation paths are different, so that the signal level difference between the confidential information and the pseudo information after despreading is not regular. As a result, it is not possible to obtain the confidential information by selecting the confidential information and the pseudo information, and it becomes more difficult to restore the confidential information.
【0049】
Further, the data transmission device of the present invention includes data sorting means for sorting transmission data including confidential information in a predetermined order with a radio station, and the transmitting means is transmission data sorted by the data sorting means. Is transmitted to the radio station.
【0050】
According to this configuration, since the radio station to which the confidential information is transmitted knows the order of rearranging the data, the confidential information can be easily restored. On the other hand, other radio stations do not know the order of rearranging the data, which makes it more difficult to restore the confidential information.
【0051】
Further, the wireless communication system of the present invention is a wireless communication system that wirelessly transmits transmission data including confidential information from a first radio station to a second radio station, and the first radio station is a second radio. A receiving means for receiving a signal transmitted by the station, an estimating means for estimating the signal propagation time between the radio station based on the received signal obtained by the receiving means, and a radio station for transmitting data at a desired reception time. The second radio station is provided with a transmission means for transmitting transmission data at a timing in consideration of the signal propagation time so as to reach the first radio station, and the second radio station sends a signal for estimating the signal propagation time to the first radio station. The reception and demographic operation of the receiving means is controlled so as to be synchronized with the transmitting means for transmitting, the receiving means for receiving and demoting the transmitting data including confidential information, and the first radio station at a preset reception time. A configuration including a reception control means is adopted.
【0052】
According to this configuration, in the second radio station, the transmission data including the confidential information arrives at the predetermined reception time, so that the confidential information is restored by demodulating the signal in synchronization with that time. Can be done. On the other hand, other radio stations cannot restore confidential information. This is because the reference time information indicating the reception and demodulation start time is determined based on the signal propagation time shared only between the first radio station and the second radio station, so that other radio stations receive and receive. This is because the reference time indicating the demodulation start time cannot be known. As a result, other radio stations cannot recover the confidential information, and security is ensured.
【0053】
Further, in the radio communication system of the present invention, the first radio station adds a synchronization series signal having a synchronization relationship with each other at a predetermined position with the radio station in the transmission data including confidential information. , A pseudo-synchronous series signal that is a pseudo-synchronous signal for a synchronous series signal and is in a synchronous relationship with each other is added, and the second radio station extracts the synchronous series signal based on a preset reception time and performs the synchronous series signal. Based on the above, a configuration is adopted in which the transmitted data including the received confidential information is corrected.
【0054】
According to this configuration, since the second radio station knows the position of the synchronization signal, the synchronization signal can be easily extracted. In addition, the second radio station will be able to perform time synchronization, phase fluctuation, and gain fluctuation correction using the extracted synchronization signal. As a result, the reception quality can be improved. On the other hand, in other radio stations, the confidential information cannot be restored, and the pseudo-synchronization signal and the synchronization signal cannot be distinguished. Thus, it is possible to obtain a wireless communication system having high security and capable of improving reception quality at a wireless station.
【0055】
Further, in the wireless communication system of the present invention, the first wireless station transmits transmission data at a timing when the transmission data arrives at a time deviated from a preset reception time with the second radio station by a predetermined time. The second radio station adopts a configuration in which transmission data arriving at a predetermined time lag is subjected to synchronization processing using a synchronization series signal to demodulate the transmission data.
【0056】
According to this configuration, it becomes more difficult for other receiving stations to recover the confidential information. Further, the transmitting station and the receiving station that transmit and receive the confidential information can restore the confidential information even if the reception time is not exactly set in advance, which increases the degree of freedom in design.
【0057】
Further, in the wireless communication system of the present invention, the first wireless station transmits confidential information in association with the deviation amount of a predetermined time, and the second wireless station uses the deviation amount of the predetermined time as recognition information for the confidential information. It is configured to perform demodulation processing using this.
【0058】
According to this configuration, the risk of leakage of confidential information to other radio stations is further reduced.
【0059】
Further, in the wireless communication system of the present invention, the second wireless station sets a search range setting means for setting a predetermined search range based on the reception time, and a peak of the received signal within the range set by the search range setting means. A configuration is adopted that includes a synchronization signal extraction means that extracts a synchronization sequence signal by searching, and a correction means that corrects transmission data including confidential information received based on the extracted synchronization sequence signal.
【0060】
According to this configuration, time synchronization, phase fluctuation correction, and gain fluctuation correction are performed by setting a search range having a narrow time width centered on a reception time that only the second radio station can know in the search range setting means. It is possible to accurately extract the synchronous sequence signal that is the basis of. As a result, the second radio station can obtain high-quality confidential information. On the other hand, in other receiving stations, since the pseudo-synchronous series signal at the same level as the synchronous series signal exists, the synchronous series signal and the pseudo-synchronous series signal cannot be distinguished from each other. It becomes very difficult to correct the signal and the gain, and it becomes more difficult to restore the confidential information.
【0061】
Further, the wireless communication system of the present invention is a wireless communication system that wirelessly transmits transmission data including confidential information from a first radio station to a second radio station, and the first radio station is a second radio. With respect to the receiving means for receiving the signal transmitted by the station, the polarization plane detecting means for detecting the polarization plane of the received wave based on the reception signal obtained by the receiving means, and the detected polarization plane, the first and second The second radio station is provided with a transmission means for transmitting transmission data including confidential information to the second radio station by a transmission wave in which the polarization plane is rotated by a predetermined amount between the second radio stations. Outputs the polarization plane detection signal to the first radio station and outputs the polarization plane characteristics of the antenna that receives the transmission data including the confidential information transmitted by the first radio station. A configuration is adopted in which a predetermined amount of rotation is performed between the first and second radio stations between the time when the transmission data including the confidential information is received and the time when the transmission data including the confidential information is received.
【0062】
According to this configuration, other radio stations cannot know the rotation information of the plane of polarization determined in advance between the first radio station and the second radio station. This makes it very difficult for other radio stations to estimate the plane of polarization of the transmitted data including the confidential information transmitted from the first radio station. As a result, it becomes very difficult for other radio stations to receive and restore the confidential information.
【0063】
Further, in the wireless communication system of the present invention, the first and second radio stations perform a process of rotating the plane of polarization between the first and second radio stations by a predetermined amount, the first and second radio stations. A configuration is adopted in which the stations are repeatedly performed at predetermined intervals.
【0064】
According to this configuration, in other radio stations, it becomes more difficult to estimate the plane of polarization of the transmission data including the confidential information transmitted from the first radio station. As a result, it becomes more difficult for other radio stations to receive and restore the confidential information.
【0065】
Further, the wireless communication system of the present invention is a wireless communication system that wirelessly transmits transmission data including confidential information from a first radio station to a second radio station, and the first radio station is a second radio. A first spread signal is formed and spread by spreading processing confidential information using an estimation means that estimates the radio propagation time and signal power attenuation based on the signal transmitted from the station and a predetermined spread code. Estimated as a spreading means that forms a second spreading signal by spreading pseudo-information using a spreading code different from the code and so as to obtain a spreading gain similar to the spreading gain of the first spreading signal. Based on the signal power attenuation estimated by the means, when the first and second spread signals reach the second radio station, the received power value of the first spread signal and the received power of the second spread signal. It is provided with a transmission means for transmitting the first and second spread signals by controlling the transmission power so that a difference of a certain value or more occurs, and the second radio station transmits the first and second spread signals. A configuration is adopted in which a despreading means for despreading and a concealed information extracting means for extracting concealed information based on the signal level of the despreaded signal are provided.
【0066】
According to this configuration, in the second radio station, when the spread secret information and the spread pseudo information are back-spread, a difference of a certain amount or more occurs between the signal level of the secret information and the signal level of the pseudo information. As a result, the second radio station can select the secret information and the pseudo information by determining the level of the secret information by the secret information extraction means, and can extract the secret information. On the other hand, in other radio stations located in a place different from the second radio station, the radio propagation path is different, so that the signal level difference between the confidential information and the pseudo information after despreading is not regular. As a result, the confidential information and the pseudo information cannot be selected to obtain the confidential information, and the confidential information cannot be restored.
【0067】
Further, the wireless communication system of the present invention is a wireless communication system that wirelessly transmits transmission data including confidential information from a first radio station to a second radio station, and the first radio station is a second radio. A first spreading signal is formed by spreading processing confidential information using an estimation means that estimates the radio propagation time and the signal arrival direction based on the signal transmitted from the station and a predetermined spreading code, and the spreading code. A diffusion means and an estimation means that form a second diffusion signal by spreading pseudo-information using a diffusion code different from that of the first diffusion signal and so as to obtain a diffusion gain similar to the diffusion gain of the first diffusion signal. When the first and second spread signals reach the second radio station, the received power value of the first spread signal and the received power value of the second spread signal are constant based on the arrival direction estimated by The second radio station is provided with a transmission means for transmitting the first and second diffusion signals in the direction in which the above difference occurs, and the second radio station is the reverse of the reverse diffusion means for despreading the first and second diffusion signals. A configuration including a confidential information extraction means for extracting the confidential information based on the signal level of the diffused signal is adopted.
【0068】
According to this configuration, in the second radio station, when the spread secret information and the spread pseudo information are back-spread, a difference of a certain amount or more occurs between the signal level of the secret information and the signal level of the pseudo information. As a result, the second radio station can select the secret information and the pseudo information by discriminating the signal level and extract the secret information. On the other hand, in other radio stations located in a place different from the second radio station, the radio propagation path is different, so that the signal level difference between the confidential information and the pseudo information after despreading is not regular. As a result, the confidential information and the pseudo information cannot be selected to obtain the confidential information, and the confidential information cannot be restored.
【0069】
Further, the wireless communication system of the present invention is a wireless communication system that wirelessly transmits transmission data including confidential information from the first and second radio stations to a third radio station, and is a first and second radio station. Is based on a network connection means for connecting to a wired network and acquiring confidential information from the network, a receiving means for receiving a signal transmitted by a third radio station, and a receiving signal obtained by the receiving means, respectively. The transmission data is transmitted at a timing considering the signal propagation time so that the transmission data reaches the third radio station at a desired reception time and an estimation means for estimating the signal propagation time with the third radio station. The third radio station includes a transmission means for transmitting, and the third radio station receives and demographs the transmission means for transmitting a signal for estimating the signal propagation time to the first radio station and transmission data including confidential information. A configuration is adopted in which a receiving means and a receiving control means for controlling a reception demodulation operation of the receiving means so as to synchronize with a preset reception time between the first and second radio stations are provided.
【0070】
According to this configuration, the first and second radio stations can acquire confidential information from the wired network via the network connection means. Then, for example, if the acquired confidential information is shared between the first radio station and the second radio station and transmitted to the third radio station, the third radio station synthesizes these divided confidential information after receiving the information. Allows the confidential information to be restored. On the other hand, other radio stations cannot restore the confidential information because they cannot know the reception time. Moreover, even if one of the reception times can be known, the confidential information is divided and cannot be completely restored.
【0071】
Further, the wireless communication method of the present invention is a wireless communication method for wirelessly transmitting transmission data including confidential information from a first radio station to a second radio station, from the second radio station to the first radio station. The first radio station estimates the signal propagation time between the first and second radio stations based on the received signal, and the first radio station receives the desired transmission data. Transmission data including confidential information is transmitted at a timing considering the signal propagation time so that the radio station arrives at the time.
【0072】
According to this method, in the second radio station, the transmission data including the confidential information arrives at the predetermined reception time, so that the confidential information is restored by demodulating the signal in synchronization with that time. Can be done. On the other hand, other radio stations cannot restore confidential information. This is because the reference time information indicating the reception and demodulation start time is determined based on the signal propagation time shared only between the first radio station and the second radio station, so that other radio stations receive and receive. This is because it is not possible to know the reference time indicating the demodulation start time. As a result, other radio stations cannot recover the confidential information, and security is ensured.
【0073】
Further, in the wireless communication method of the present invention, the desired reception time is at least one round trip between the first and second radio stations before transmitting transmission data including confidential information from the first radio station. By transmitting and receiving signals, it is set between the first and second radio stations based on the signal propagation time.
【0074】
According to this method, the signal propagation time is completely information that can be shared only by the first radio station and the second radio station, so that other radio stations cannot know this time information. As a result, it becomes impossible for other radio stations to obtain confidential information.
【0075】
Further, in the wireless communication method of the present invention, a pseudo symbol is added to a position predetermined with the wireless station in the transmission data including the confidential information.
【0076】
According to this method, since the second radio station knows the position of the pseudo symbol, it is possible to easily extract the confidential information by removing only the pseudo symbol after receiving and demodulating the transmission data. On the other hand, even if the transmitted data can be demodulated by other radio stations, the confidential information cannot be extracted due to the existence of the pseudo symbol.
【0077】
Further, in the wireless communication method of the present invention, synchronous series signals having a synchronous relationship with each other are added to positions predetermined with the wireless station in the transmission data including confidential information, and the wireless communication methods have a synchronous relationship with each other. A pseudo-synchronous sequence signal is added.
【0078】
According to this method, since the second radio station knows the position of the synchronization signal, the synchronization signal can be easily extracted. The second radio station will be able to perform time synchronization, phase fluctuation correction, gain fluctuation correction, etc. using the extracted synchronization signal. As a result, the reception quality can be improved. On the other hand, in other radio stations, the confidential information cannot be restored, and the pseudo-synchronization signal and the synchronization signal cannot be distinguished. Thus, the security is high and the reception quality at the second radio station can be improved.
【0079】
BEST MODE FOR CARRYING OUT THE INVENTION
The gist of the present invention is that when transmission data including confidential information is transmitted wirelessly from a first wireless station to a second wireless station, the first wireless station and the second wireless station are transmitted before the confidential information is transmitted. By transmitting and receiving signals between the two, the radio propagation path environment shared only between the first radio station and the second radio station is estimated, and the estimated radio propagation path environment is taken into consideration in the first. Confidential information is transmitted from the radio station to the second radio station. As a result, the confidential information cannot be restored by other radio stations having different radio propagation path environments.
【0080】
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
【0081】
(Embodiment 1) In FIG. 1, 100 indicates a wireless communication system according to the first embodiment of the present invention as a whole. The wireless communication system 100 has a transmitting station 101 and a receiving station 102. Here, the transmitting station 101 and the receiving station 102 simply refer to the side that transmits the confidential information as the transmitting station 101 and the side that receives the confidential information as the receiving station 102, and they transmit and receive each other. Has a part.
【0082】
The transmitting station 101 has a propagation environment estimation unit 101c and a propagation environment adaptation unit 101d in addition to the transmission unit 101a and the reception unit 101b. The propagation environment estimation unit 101c estimates the propagation environment of the transmission line 103 based on the received signal. The propagation environment adaptation unit 101d controls the transmission operation of the transmission unit 101a according to the estimation result obtained by the propagation environment estimation unit 101c.
【0083】
The receiving station 102 has a time control unit 102c in addition to the transmitting unit 102a and the receiving unit 102b. The time control unit 102c gives a predetermined delay time to the transmission and controls the reception operation in time with reference to the reception time point of the reception unit 102b.
【0084】
Here, the specific configuration of the transmitting station 101 is shown in FIG. 2, and the specific configuration of the receiving station 102 is shown in FIG. As shown in FIG. 2, the transmitting station 101 inputs the user data D1 to the encryption unit 111. Further, the encryption key generated by the encryption key generation unit 112 is input to the encryption unit 111, and the reference clock generated by the reference clock generation unit 113 is input to the encryption unit 111 via the control channel unit 114. The encryption unit 111 forms encrypted data by encrypting the user data D1 using the encryption key, and sends the encrypted data to the burst signal formation unit 115.
【0085】
An encryption key and a control channel signal are input to the burst signal forming unit 115. The burst signal formed by the burst signal forming unit 115 is input to the modulation unit 116. The modulation unit 116 performs a predetermined digital modulation process such as TDMA (Time Division Multiple Access) modulation on the input signal, and sends the processed signal to the buffer 117.
【0086】
The buffer 117 outputs the once stored transmission signal to the wireless transmission unit (transmission RF) 119 that follows at the timing of the output control signal input from the timing control unit 118. The wireless transmission unit 119 performs wireless transmission processing such as digital-to-analog conversion processing and up-conversion on the transmission signal, and supplies the processed signal to the antenna as AN11.
【0087】
Here, the timing control unit 118 corresponds to the propagation environment adaptation unit 101d in FIG. 1, and inputs the network reference time from the reference clock generation unit 113 and the transmission delay amount from the delay amount estimation unit 120. Here, the delay amount estimation unit 120 corresponds to the propagation environment estimation unit 101c in FIG.
【0088】
Then, the timing control unit 118 controls the output timing of the buffer 117 so that the receiving station 102 can receive the confidential information signal at the network reference time set in advance between the two stations in consideration of the network reference time and the transmission delay amount. To do.
【0089】
The transmitting station 101 transmits the network reference time before transmitting the confidential information, and then the confidential information consisting of the encrypted user data and the encryption key is timing in consideration of the signal propagation time on the transmission line 103. It is designed to be sent with.
【0090】
The reception unit 101b of the transmission station 101 inputs the reception signal obtained by the antenna AN11 to the radio reception unit (reception RF) 121. The wireless reception unit 121 performs wireless processing such as down-conversion and analog-digital conversion processing on the received signal, and sends the processed signal to the demodulation unit 122. The demodulation unit 122 performs a predetermined digital demodulation process such as TDMA demodulation on the input signal, and sends the processed signal to the stream forming unit 123 and the delay amount estimation unit 120.
【0091】
The stream forming unit 123 converts the burst signal into the original data stream by performing the reverse processing of the burst signal forming unit 115 described above. The decryption unit 124 inputs the data stream and also inputs the encryption key from the encryption key generation unit 112, and decrypts the encrypted data stream using the encryption key.
【0092】
Next, the specific configuration of the receiving station 102 will be described with reference to FIG. As described above, the receiving station 102 includes a transmitting unit 102a, a receiving unit 102b, and a time control unit 102c. The transmission unit 102a inputs the user data D2 to the encryption unit 130. Further, the encryption key extracted by the encryption key extraction unit 131 of the reception unit 102b is input to the encryption unit 130. As a result, the encryption unit 130 encrypts the user data D2 using the encryption key common to the transmission station 101.
【0093】
In addition to the encrypted user data, the synchronization code generated by the synchronization code generation unit 133 is input to the burst signal formation unit 132. The burst signal forming unit 132 converts the encrypted data and the synchronization code into a burst-shaped transmission signal and sends it to the modulation unit 134. The modulation unit 134 performs a predetermined digital modulation such as TDMA modulation on the input signal, and sends the modulated signal to the buffer 135.
【0094】
The buffer 135 outputs the once stored transmission signal to the wireless transmission unit (transmission RF) 136 that continues at the timing of the output control signal input from the timing control unit 137 of the time control unit 102c. The wireless transmission unit 136 performs wireless transmission processing such as digital-to-analog conversion processing and up-conversion on the transmission signal, and supplies the processed signal to the antenna AN12.
【0095】
The reception unit 102b of the reception station 102 inputs the reception signal obtained by the antenna AN12 to the radio reception unit (reception RF) 140. The wireless reception unit 140 performs wireless processing such as down-conversion and analog-digital conversion processing on the received signal, and sends the processed signal to the demodulation unit 141. The demodulation unit 141 performs a predetermined digital demodulation process such as TDMA demodulation on the input signal, and sends the processed signal to the stream forming unit 142.
【0096】
The stream forming unit 142 converts the burst-shaped signal into the original data stream by performing the reverse processing of the burst signal forming unit 132 described above. The decryption unit 143 inputs the data stream and the encryption key extracted by the encryption key extraction unit 131, and decrypts the encrypted data stream using the encryption key.
【0097】
Here, the output of the wireless receiver 140 is also output to the reference clock extraction unit 144. The reference clock extraction unit 144 extracts the control channel signal and the network reference time from the received signal, and sends them to the timing control unit 137 and the timer 145. The timing control unit 137 first synchronizes the operation timing with the control channel signal. Next, the timing control unit 137 is adapted to transmit a transmission signal by transmitting an output control signal to the buffer 135 after a predetermined time Td with reference to the network reference time. Incidentally, the processing delay generated at the receiving station 102 is adjusted by the time Td.
【0098】
As a result, the transmitting station 101 can calculate the signal propagation time in the transmission line from the network reference time, the delay time Td, and the reception time of the synchronization code.
【0099】
The timer 145 first synchronizes the operation timing with the control channel signal. Next, the timer 145 sends a control signal for starting the demodulation operation to the demodulation unit 141 at the network time Tk. In this way, the receiving station 102 performs reception demodulation at the network time Tk without time synchronization (or by limiting the synchronization range to a narrow range).
【0100】
Since synchronization has already been performed on the transmitting station 101 side (that is, the network time Tk itself is the synchronized time), the receiving station can perform normal demodulation processing at the network time Tk.
【0101】
Further, the encryption key extraction unit 131 inputs the data stream from the stream forming unit 142 and the network time information from the timer 145, and extracts the encryption key from the data stream at the network time Tk.
【0102】
In practice, the transmitting station 101 first transmits information including the network reference time formed by the control channel unit 114. In some cases, this transmission is performed multiple times. As a result, the receiving station 102 can perform a receiving operation synchronized with the network reference time with high accuracy.
【0103】
When the response signal arrives from the receiving station 102, the transmitting station 101 estimates the signal propagation time in the transmission line 103 from the reception time and the network reference time in the delay amount estimation unit 120. The transmitting station 101 may receive the response signal from the receiving station 102 a plurality of times in order to improve the estimation accuracy (for example, the error is one symbol time or less).
【0104】
Further, when transmitting the encryption key, the transmitting station 101 transmits the encryption key from the network time Tk at which the receiving station starts the receiving operation and the propagation delay by the timing control unit 118 so that the receiving station 102 reaches the network time Tk exactly. Control the timing. As a result, at the receiving station 102, since the encryption key arrives at the predetermined network time Tk, the encryption key can be obtained by demodulating the signal in synchronization with that time. After that, the transmitting station 101 uses the encryption key to decrypt the encrypted data to be sequentially received, and transmits the encrypted data while encrypting the user data D2.
【0105】
Next, the operation of the wireless communication system 100 of this embodiment will be described. Communication of the wireless communication system 100 is performed according to the procedure shown in FIG.
【0106】
First, the transmitting station 101 transmits (transmission 1B) a control signal including a network reference time as a signal (communication 1) for synchronizing with the receiving station 102. When the receiving station 102 receives communication 1 (reception 1T), the delay time (T1) and the fixed time (T2) until the next transmission (transmission 2T) are based on the time and the given network reference time. Set the receiving terminal reference time (that is, the network time Tk described above) of the next communication 3 after that. The receiving station 102 transmits a response signal (communication 2) to the transmitting station 101 (transmission 2T) after a delay time (T1) has elapsed from the reception 1T.
【0107】
Incidentally, the transmitting station 101 and the receiving station 102 hold the information of the delay time T1 and the fixed time T2 in advance as shared information.
【0108】
At the same time that the transmitting station 101 receives the communication 2 (reception 2B), the propagation environment estimation unit 101c estimates the propagation path 103 from the control signal output by the transmission 1B and the response signal received by the reception 2B. Specifically, the delay amount estimation unit 120 provided in the transmitting station 101 propagates from the time of transmission 1B and reception 2B, the delay time (T1) at the receiving station, the processing delay generated in each device, and the like. The signal propagation time on the road 103 is calculated.
【0109】
Here, the processing delay in the device at the transmitting station 101 and the receiving station 102 is substantially constant depending on the configuration of the device, and can be treated as known information during system operation. The propagation environment adaptation unit 101d (that is, the timing control unit 118) of the transmission station 101 performs a signal (communication) at a timing that synchronizes with the reception terminal reference time (that is, network time Tk) of the reception station 102 from the signal propagation time and the processing delay. 3) is sent (send 3B).
【0110】
Communication 3 includes confidential information (in the case of this embodiment, an encryption key) that is not desired to be leaked to other than the receiving station 102. The information of communication 3 is received (received 3T) by the receiving station 102 after being delayed by the time obtained by adding the signal propagation time of the propagation path 103 to the processing delay of the transmitting station 101. The receiving station 102 starts the receiving 3T and demodulates based on the receiving terminal reference time set in the receiving 1T. After that, the transmitting station 101 and the receiving station 102 perform communication after communication 4 while encrypting and decrypting information using the encryption key transmitted in communication 3.
【0111】
Here, communication 3 will be described in more detail with reference to FIG. In FIG. 5, the receiving terminal 1 is the receiving station 102 to which the confidential information is transmitted by the transmitting station 101, and the receiving terminal 2 is another terminal.
【0112】
Assuming that the time from communication 1 to communication 3 is sufficiently short, the transmission speed of radio waves is very high with respect to the moving speed of the receiving station (reception terminal 1) 102, so the positional relationship between the transmitting station 101 and the receiving station 102 Even if there is a change, there is no significant change in the environment of the propagation path 103, particularly the signal propagation time (propagation path delay 1).
【0113】
For example, assuming that it takes 1 second from communication 1 to communication 3 and the receiving station 102 is moving at 100 [km] per hour, the change in the propagation path delay 1 is about 100 [ns]. Therefore, the reception terminal reference time 1 set by the reception station (reception terminal 1) 102 in reception 1T and the transmission 3B adjusted by the propagation environment adaptation unit 101d of the transmission station 101 pass through the propagation path 103 to the reception station 102. The time of reception 3T received by is almost synchronized, and there is no need to adjust the time.
【0114】
As a result, the receiving terminal 1 can restore the communication information by starting reception and demodulation at the receiving terminal reference time 1 and sequentially demodulating the received reception terminal 1 communication signal.
【0115】
On the other hand, consider a case where a third party (reception terminal 2) other than the reception station (reception terminal 1) 102 intercepts this communication 3 and tries to restore the information. The receiving terminal 2 can receive information between communication 1 and communication 2, but the signal of communication 3 includes reference time information (network time Tk) indicating the reception and demodulation start time. Information cannot be restored because there is no such information.
【0116】
This reference time information is calculated by the receiving terminal 1 based on the reception 1T, and the transmitting station 101 estimates the signal propagation time (propagation path delay 1) of the propagation path 103 by communication 1 and communication 2 and signals at the reference time. Is the target time for controlling transmission so that This reference time depends on the propagation path environment (that is, the propagation path). As a result, it is impossible for the receiving terminal 2 to know the correct propagation path delay time 2 in advance or by measuring it.
【0117】
In this way, the receiving terminal 2 cannot know the time when the communication 3 is sent. Therefore, the correct receiving terminal reference time 2 cannot be set for the receiving terminal 2 communication signal. As a result, the information of communication 3 cannot be restored correctly. As a result, communication 3 can ensure high security.
【0118】
According to the above configuration, the transmitting station 101 and the receiving station 102 share the same reference time (network reference time), the signal propagation time between the transmitting station 101 and the receiving station 102 is estimated, and the transmitting station 101 is networked. The transmission signal is transmitted at the timing considering the signal propagation time so that the signal is received by the receiving station 102 at the time Tk, and the receiving station 102 receives and demolishes the signal transmitted at the network time Tk. As a result, a highly secure wireless communication system 100 can be realized.
【0119】
(Embodiment 2) The wireless communication system of this embodiment has the same configuration as the wireless communication system 100 of the first embodiment except that the order of the information is rearranged according to a predetermined format. It consists of. As a result, the wireless communication system of this embodiment can perform communication with higher security.
【0120】
Practically, this rearrangement of the information order may be performed by the burst signal forming unit 115 (FIG. 2) of the transmitting station 101. Then, the process of restoring the rearranged signals may be performed by the stream forming unit 142 (FIG. 3) of the receiving station 102. Here, it is assumed that the order rearrangement rule is determined in advance only between the transmitting station 101 and the receiving station 102.
【0121】
Thus, in the wireless communication system of this embodiment, the transmitting station 101 and the receiving station 102 share the same reference time, the signal propagation time in the transmission line 103 is estimated, and the signal propagation time is taken into consideration in the transmitting station 101. The transmission signal is transmitted at the timing, and in addition to demodulating the signal received at the network time Tk exactly at the receiving station 102, the transmission data is sorted in a known format only between stations communicating with each other. As a result, in addition to the effect of the first embodiment, a wireless communication system with higher security can be realized.
【0122】
By the way, it is not necessary to limit the format that defines the order of information to one, and if multiple types of formats are prepared, security against a third party can be further improved.
【0123】
(Embodiment 3) The wireless communication system of this embodiment has a configuration in which a pseudo symbol is mixed with a confidential information symbol and transmitted in addition to the configuration of the first embodiment described above. Practically, the process of mixing the pseudo symbol with the confidential information symbol is performed by the burst signal forming units 115 and 132 (FIGS. 2 and 3). Further, the process of removing the pseudo symbol from the received signal is performed by the stream forming units 123 and 142 (FIGS. 2 and 3). Thereby, the wireless communication system of this embodiment can further improve the security as compared with the wireless communication system 100 of the first embodiment.
【0124】
The operation of the wireless communication system of this embodiment will be described again with reference to FIGS. 4 and 5 used in the first embodiment.
【0125】
In the wireless communication system of this embodiment, confidential information and pseudo information are arranged in communication 3 (FIG. 4) according to a predetermined format. Here, it is assumed that the predetermined format is that the symbols 0, 2, 5, and 9 in FIG. 5 are pseudo symbols, and the others are concealed symbols. At this time, the transmitting station sets the legitimate information in the secret symbol and the pseudo information in the pseudo symbol, and transmits the communication 3 (transmission 3T).
【0126】
The information of communication 3 is received (received 3T) by the receiving station 102 after being delayed by the time obtained by adding the signal propagation time of the propagation path 103 to the processing delay of the transmitting station 101. The receiving station 102 starts the receiving 3T with reference to the receiving terminal reference time (network time Tk) set in the receiving 1T.
【0127】
In the receiving terminal 1, since the symbol 0 of the receiving terminal 1 communication signal is the same time as the receiving terminal reference time 1, only the hidden symbol is extracted, demodulated and decoded by selecting and removing the pseudo symbol according to the above format. be able to. After that, the transmitting station 101 and the receiving station 102 perform communication after communication 4 while performing encryption based on the information transmitted in communication 3.
【0128】
In the receiving terminal 2, since the symbol 0 of the receiving terminal 2 communication signal and the receiving terminal reference signal 2 are not at the same time, the synchronization required for demodulation cannot be achieved. As a result, the received signal cannot be demodulated.
【0129】
In addition to this, even if the received signal can be demodulated and decoded, it becomes impossible to obtain legitimate confidential data. For example, in the case of burst communication, it is possible to estimate the synchronization time from the waveform of the received power, but by inserting a pseudo symbol as in this embodiment, it is possible for a third party to perform synchronization. It will be very difficult. As a result, communication 3 can ensure higher security.
【0130】
Thus, according to the above configuration, in addition to the configuration of the first embodiment, by mixing the secret information with the pseudo information and transmitting the information, a communication system with higher security can be realized.
【0131】
(Embodiment 4) In this embodiment, in addition to mixing the pseudo information with the confidential information, the synchronization series is further mixed and transmitted. As a result, it becomes more difficult for the receiving station that is not the transmission target of the confidential information to restore the confidential information, whereas the receiving station that is the transmission target of the confidential information uses the synchronization sequence to provide the confidential information with good reception quality. Obtainable.
【0132】
Practically, in the wireless communication system of this embodiment, the burst signal forming unit 115 of FIG. 2 is configured as shown in FIG. 6, and the demodulation unit 141 and the stream forming unit 142 shown in FIG. 3 are shown in FIG. By configuring the above, mixing of pseudo signals and removal of pseudo signals are realized. Further, in this embodiment, in order to simplify the explanation, only the case where the encrypted data is transmitted as confidential information will be described.
【0133】
As shown in FIG. 6, the burst signal forming unit 300 of this embodiment inputs the encrypted user data D3 to the burst signal generation circuit 301. Further, the unique word sequence generated by the unique word generation circuit 302 is input to the burst signal generation circuit 301, and the pseudo signal sequence generated by the pseudo signal generation circuit 30 3 is input to the burst signal generation circuit 301 . The burst signal generation circuit 301 converts the user data sequence, the unique word sequence, and the pseudo signal sequence into a burst-shaped signal, and sends the converted signal to the scramble circuit 304.
【0134】
The scramble circuit 304 scrambles the burst signal with the scramble pattern generated by the scramble pattern generation circuit 306, and sends the scrambled signal to the puncture circuit 305. The puncture circuit 305 punctures the scrambled signal with the puncture pattern generated by the puncture pattern generation circuit 307. As a result, as shown in FIG. 6, the signal D4 after the puncture process is in a state of toothlessness in which a pseudo signal and a unique word are randomly mixed in the user data. Then, the signal D4 after this puncture processing is sent to the modulation circuit 116 (FIG. 2). As the puncture process, a specific symbol may be inserted instead of the toothless state.
【0135】
Next, the configuration of the receiving station that extracts only the user data D3 from the scrambled and punctured signal D4 will be described with reference to FIG. 7. The demodulator circuit 310 inputs the scrambled and punctured received signal D4 output from the radio receiver (receiver RF) 140 (Fig. 3) to the phase and gain adjustment circuit (phase / gain adjustment) 311. At the same time, input to the time synchronization and unique word extraction circuit (time synchronization / unique word extraction) 312.
【0136】
The time synchronization / unique word extraction circuit 312 inputs the network time Tk described in the above-described first embodiment from the timer 145, and extracts the unique word sequence from the received signal D4 based on the timing of the network time Tk. Then, the extracted unique word sequence is sent to the frequency synchronization circuit 313 and also to the phase and gain detection circuit (phase / gain detection) 314.
【0137】
The frequency synchronization circuit 313 detects a frequency error from the extracted unique word sequence, and sends frequency information to the phase and gain adjustment circuit (phase / gain adjustment) 311. The phase / gain detection circuit 314 detects the phase rotation amount and the gain from the unique word sequence, and sends the detection result to the phase / gain adjustment circuit 311. Incidentally, the frequency information detected by the frequency synchronization circuit 313 is also used as a synchronization signal of another circuit.
【0138】
As a result, the phase / gain adjustment circuit 311 can perform phase adjustment and gain adjustment using the phase rotation amount and gain accurately detected based on the unique word sequence, and thus scramble puncture including phase fluctuation and gain fluctuation during transmission. It will be possible to accurately correct the Chua data D4.
【0139】
The phase and gain-adjusted scrambled puncture data is sent to the data selector 321 of the stream forming unit 320. The data selector 321 inputs the network time Tk from the timer 145, and also inputs the phase information and the signal amplitude information from the phase / gain detection circuit 314. Then, based on this information, the burst-shaped signal is returned to the original data stream, and the gap between the signals formed by the puncture processing is filled. This data stream is sent to the descramble circuit 322.
【0140】
The descramble circuit 322 inputs the network time Tk from the timer 145, and also inputs the scramble pattern from the scramble pattern generation circuit 323. The scramble pattern generation circuit 323 generates the same scramble pattern as the scramble pattern generation circuit 306 (FIG. 6) of the transmitting station. As a result, the descramble circuit 322 can remove the pseudo signal sequence and the unique word sequence from the data stream and output only the user data D3.
【0141】
Here, FIG. 8 shows the detailed configuration of the time synchronization / unique word extraction circuit 312. The time synchronization / unique word extraction circuit 312 inputs the scrambled puncture data D4 to the convolvator circuit 330. In addition, the network time Tk from timer 145 (Fig. 7) is input to controller 331. The converter circuit 330 is time controlled by the controller 331. Then, for a certain period of time based on the network time Tk, the correlation value between the unique word sequence extracted from the scrambled puncture data according to the format and the unique word sequence generated by the unique word generation circuit 332 is taken. Incidentally, the unique word generation circuit 332 generates the same unique word sequence as the transmitting station side. The combiner circuit 330 sends the correlation value obtained by this to the peak search circuit 333.
【0142】
The peak search circuit 333 searches for the peak of the correlation value within the search range set by the search range setting circuit 334. The search range setting circuit 334 sets a search range having a predetermined time width centered on a time point after a predetermined time from the network time Tk output from the controller 331. Here, since the receiving station knows the arrangement of the unique word sequence and the pseudo signal sequence in advance, it is possible to roughly know how much the data of the unique word sequence is demodulated at a time later than the network time Tk. Therefore, in the search range setting circuit 334, the search range centered on this approximate time point is set.
【0143】
The peak search circuit 333 searches for the peak of the correlation value within the search range. The peak search result is sent to the unique word selection circuit 335. The unique word selection circuit 335 selects the signal sequence corresponding to the peak of the correlation value as the unique word.
【0144】
FIG. 9 shows the relationship between the correlation value obtained by the convolvator circuit 330 and the unique word (synchronous word). FIG. 9A shows an example when there is one unique word (A in the figure is a unique word), for example, when transmitting a network reference time. In such a case, only one large peak appears, and a search for time synchronization can be performed over a wide range such as the time width T10. That is, when a third party tries to obtain a synchronization signal for the purpose of intercepting communication, the synchronization signal may be detected relatively easily.
【0145】
On the other hand, as in this embodiment, when a signal in which a unique word sequence and a pseudo signal sequence are mixed is received, the relationship between the correlation integral value obtained by the convolvator circuit 330 and the unique word is shown in FIG. Shown in (b). Here, it is assumed that the pseudo signal sequence is arranged with a certain time offset from the unique word sequence, and the pseudo signal sequence is a signal sequence having a high correlation with the unique word sequence. As described above with respect to FIG. 6, since the unique word sequence and the pseudo signal sequence have a high correlation, the correlation value output by the convolvator circuit 330 shows a high value between the unique word sequence and the pseudo signal sequence. For example, if one unique word sequence and four pseudo signal sequences exist in the scrambled punchure data, multiple peaks (five of A to E in the figure) appear at almost equal levels in the correlation value. When the peak of the unique word is C (A, B, D, E are pseudo signals), the unique word for time synchronization is detected by performing the peak search only in the narrow time width T11 in the figure. be able to.
【0146】
That is, in the receiving station of this embodiment, the search range setting unit 334 sets a search range T11 having a narrow time width centered on the network time Tk that only this receiving station can know, thereby detecting time synchronization and phase fluctuation. And the unique word that is the basis for detecting the gain fluctuation can be accurately extracted. By the way, in other receiving stations, since the pseudo signal having a high correlation with the unique word exists, the unique word and the pseudo signal cannot be distinguished, so that the time synchronization, the phase fluctuation correction, and the gain correction are correct. It cannot be done, and it becomes more difficult to intercept the communication. In this embodiment, a unique word sequence composed of a plurality of symbols is given as an example, but it may be replaced with a pilot signal composed of one symbol unit.
【0147】
Next, the operation of the wireless communication system of this embodiment will be described with reference to FIG. 10, focusing on the synchronous operation on the receiving station 102 side. That is, since the communication 1 and the communication 2 perform the same operation as that of the above-described first embodiment, the description thereof will be omitted here.
【0148】
The propagation environment adaptation unit 101d of the transmission station 101 synchronizes with the reception terminal reference time (network time Tk) of the reception station 102 based on the signal propagation time estimated by the propagation environment estimation unit 101c and the processing delay. Communication 3) is transmitted (transmission 3B). In communication 3, a synchronous sequence and a pseudo-synchronous sequence (the above-mentioned pseudo signal sequence is used, but in this embodiment, it functions as a pseudo signal for the synchronous sequence rather than a pseudo signal for confidential information, based on a preset format. Confidential information is arranged and transmitted (hereinafter referred to as this).
【0149】
The information of communication 3 is delayed by the time obtained by adding the signal propagation time to the processing delay time of the transmitting station 101, and is received (reception 3T) by the receiving station 102 at the receiving terminal reference time. The receiving station 102 starts receiving 3T based on the receiving terminal reference time set in receiving 1T, and extracts a synchronization sequence (unique word sequence) from this received signal based on the format. Then, using this, synchronization of time, frequency, phase, etc. is performed. After that, the confidential information is separated from the received signal received by the reception 3T, and the information is demodulated and decoded. After that, the transmitting station 101 and the receiving station 102 perform communication after communication 4 while performing encryption based on the information (for example, an encryption key) transmitted in communication 3.
【0150】
Here, communication 3 will be described in more detail with reference to FIG. In FIG. 10, symbols 4, 8, and F are synchronous series, and symbols 3, 7, and E are pseudo-synchronous series. Further, the transmitting station 101 uses the receiving terminal 1 as the receiving station 102 as the transmitting destination, and the receiving terminal 2 as another terminal.
【0151】
When the frames arranged as shown in FIG. 10 are transmitted, the synchronization series is received at the receiving terminal 1 in synchronization with the receiving terminal reference time 1, so that the synchronization series (symbol 4) is followed by the preset format. , 8, F) and pseudo-synchronous series (symbols 3, 7, E) can be easily selected and selected.
【0152】
The receiving station 102 uses this synchronization sequence to synchronize the time, frequency, and phase. Even if the signal received by the receiving terminal 1 (reception terminal 1 communication signal) has an error with respect to the receiving terminal reference time 1, if the error is such that the pseudo synchronization series is not erroneously selected, it is corrected by this synchronization series. be able to. As a result, the reception quality can be improved.
【0153】
Further, when the phase information is modulated by the synchronization sequence, the phase synchronization can also be performed, so that the information of the communication 3 transmitted at the same time can be synchronously detected and the detection equivalent thereto can be performed. It is possible to perform communication with higher quality than the communication method described in 1.
【0154】
On the other hand, the receiving terminal 2 cannot know the time when the communication 3 is sent, and cannot detect the correct synchronization sequence for the receiving terminal 2 communication signal. For example, if a pseudo-synchronous sequence similar to or the same as the synchronous sequence is used, the receiving terminal 2 will synchronize using the pseudo-synchronized sequence (symbols 3, 7, E) close to the receiving terminal reference time 2. Become. As a result, the information transmitted in communication 3 cannot be demodulated and decoded correctly. As a result, communication 3 can ensure high security.
【0155】
Thus, according to the above configuration, in addition to the configuration of the first embodiment, by mixing the synchronous series and the pseudo-synchronous series with the confidential information on the transmitting side, the security can be further improved and the reception quality can be improved. A wireless communication system can be realized.
【0156】
Incidentally, in this embodiment, since the receiving station 102 starts demodulation and decoding of the received signal with reference to the receiving terminal reference time 1, the transmitting station 101 is a symbol even if the frame format or the like is not set in advance. Pseudo-symbols can be arbitrarily added before 0 or after symbol 9. By doing so, since the burst length is variable, it becomes difficult to estimate the position of the synchronization series from the shape of the signal amplitude, and the confidentiality from a third party can be further enhanced. Further, by changing the amplitude of the symbol inserted in the puncture circuit 305, it is possible to make the estimation from the shape of the signal amplitude even more difficult.
【0157】
(Embodiment 5) In FIG. 11 in which the corresponding portions corresponding to those in FIG. 1 are designated by the same reference numerals, 500 indicates the wireless communication system according to the fifth embodiment of the present invention as a whole. The wireless communication system 500 has substantially the same configuration as the wireless communication system 100 of the first embodiment described above, except that the transmission station 501 has two transmission units 502 and 503.
【0158】
That is, the transmission station 501 of the wireless communication system 500 is composed of a propagation environment estimation unit 101c, a propagation environment adaptation unit 101d, a first transmission unit 502, a second transmission unit 503, and a reception unit 101b. In practice, the first transmitter 502 and the second transmitter 503 do not have the transmitter 101a as shown in FIG. 2, but two antennas are arranged at different positions, and the signal processing is the same as that of the transmitter 101a. It is designed to be performed by one processing unit consisting of the above configuration. The receiving station 102 includes a transmitting unit 102a, a receiving unit 102b, and a time control unit 102c. Communication is performed by the communication procedure shown in FIG. 12 via the first transmission line 504 and the second transmission line 505.
【0159】
First, the transmission station 501 transmits (transmission 10B) a control signal (communication 10) including a network reference time from the first transmission unit 502 while controlling the output so as to pass through the first propagation path 504. When the receiving station 102 receives the communication 10 (reception 10T), the delay time (T10) until the next transmission (transmission 20T) and the reception of the next communication 30 after a certain time (T20) are received based on that time. Set the terminal reference time 10 and so on. The receiving station 102 transmits a response signal (communication 20) to the transmitting station 501 (transmission 20T) after a delay time (T10) has elapsed from the reception 10T.
【0160】
Incidentally, the transmitting station 501 and the receiving station 102 hold the information of the delay time T10 and the fixed time T20 and the information of the delay time T11 and the fixed time T21, which will be described later, as shared information in advance.
【0161】
At the same time that the transmitting station 501 receives the communication 20 (reception 20B), the propagation environment estimation unit 101c estimates the state of the first propagation path 504 from the control signal transmitted by the transmission 10B and the response signal received by the reception 20B. Specifically, the delay amount estimation unit provided in the transmitting station 501 propagates from the time of transmission 10B and reception 20B, the delay time (T10) at the reception station 102, the processing delay generated in each device, and the like. The signal propagation time on the road 504 is calculated. Incidentally, the processing up to this point is the same as the processing described above in the first embodiment.
【0162】
Similarly, the transmitting station 501 transmits a signal (communication 11) (transmission 11B) from the second transmitting unit 503 while controlling the output so as to pass through the second propagation path 505. When the receiving station 102 receives the communication 11 (reception 11T), the delay time (T11) until the next transmission (transmission 21T) and the reception of the next communication 31 after a certain time (T21) are received based on that time. Set the terminal reference time 20. The receiving station 102 transmits a response signal (communication 21) to the transmitting station 501 (transmission 21T) after a delay time (T11) has elapsed from the reception 20T.
【0163】
At the same time that the transmitting station 501 receives the communication 21 (reception 21B), the propagation environment estimation unit 101c receives the second propagation path 505 from the signal transmitted by the transmission 11B (communication 11) and the response signal received by the reception 21B (communication 21). Estimate the state of. Specifically, the delay amount estimation unit provided in the transmitting station 501 propagates from the time of transmission 11B and reception 21B, the delay time (T11) at the reception station 102, the processing delay generated in each device, and the like. Calculate the signal propagation time on road 505.
【0164】
From the signal propagation time and processing delay of the first propagation path 504, the propagation environment adaptation unit 101d of the transmission station 501 transmits a signal (communication 30) to the first transmission unit 502 so as to synchronize with the reception terminal reference time 10 of the reception station 102. Transmission (transmission 30B) while controlling the output so as to pass through the first propagation path 504.
【0165】
Similarly, the propagation environment adaptation unit 101d of the transmitting station 501 sets a signal (communication 31) so as to synchronize with the receiving terminal reference time 20 of the receiving station 102 from the signal propagation time and the processing delay of the second propagation path 505. 2 Transmission (transmission 31B) is performed while controlling the output from the transmission unit 503 so as to pass through the second propagation path 505.
【0166】
Here, the communication 30 and the communication 31 include confidential information such as an encryption key. The information of the communication 30 is delayed by the time obtained by adding the signal propagation time in the first propagation path 504 to the processing delay of the transmission station 501, and is received (reception 30T) by the reception station 102. Similarly, the information of the communication 31 is also delayed by the time obtained by adding the signal propagation time in the second propagation path 505 to the processing delay, and is received (reception 31T) by the receiving station 102.
【0167】
The receiving station 102 starts receiving 30T and receiving 31T based on the receiving terminal reference time 10 and the receiving terminal reference time 20 set in the reception 10T and the reception 11T, and demodulates and decodes the received data. After that, the transmitting station 501 and the receiving station 102 perform communication after communication 4 while performing encryption and decryption based on the information (encryption key) transmitted in communication 30 and communication 31.
【0168】
Communication 30 and communication 31 will be described in more detail with reference to FIG. In FIG. 13, the transmitting station 501 uses the receiving terminal 1 as the destination receiving station 102, and the receiving terminal 2 as another terminal.
【0169】
Assuming that the time from communication 10 and communication 11 to communication 30 and communication 31 is sufficiently short, the propagation speed of radio waves is very high with respect to the moving speed of the receiving station (reception terminal 1) 102, so the transmission station 501 and reception are received. Even if there is a change in the positional relationship of the station 102, there is no significant change in the environment of the propagation path, particularly the delays of the first propagation path 504 and the second propagation path 505 (propagation path delay 10, propagation path delay 20).
【0170】
Therefore, the receiving terminal reference time 10 and the receiving terminal reference time 20 set by the receiving station (receiving terminal 1) 102 at the receiving 10T and the receiving 11T, respectively, and the transmitting 30B adjusted by the propagation environment adaptation unit 101d of the transmitting station 501, The transmission 31B is almost synchronized with the reception terminal reference times 10 and 20 received by the reception station 201 via the propagation paths 504 and 505, and there is no need to adjust the time.
【0171】
Therefore, the receiving terminal 1 sequentially demodulates the received receiving terminal 1 communication signal based on the receiving terminal reference time 10 for the communication 30 and the receiving terminal reference time 20 for the communication 31. You can restore the confidential information with.
【0172】
On the other hand, consider a case where a third party (reception terminal 2) who is not the destination intercepts the communication 30 and the communication 31 and tries to restore the information. The receiving terminal 2 can receive the information of communication 10, communication 11, communication 20, and communication 21, but the signals of communication 30 and communication 31 include the receiving terminal reference times 10 and 20 indicating the start of communication. Confidential information cannot be restored because it is not included.
【0173】
This reference time information is calculated by the receiving terminal 1 based on the reception 10T and 11T, and the transmitting station 501 uses the communication 10, 11, 20, and 21 to transmit the first and second propagation paths 504 and 505 signal propagation time (propagation). This is the target time for estimating the road delays 10 and 20) and controlling the transmission so that the signal reaches the reference time. This reference time depends on the propagation path environment (that is, the propagation path). As a result, the receiving terminal 2 cannot know the correct propagation path delay times 10 and 20 in advance or by measuring them.
【0174】
Therefore, since the receiving terminal 1 communication signal received by the receiving terminal 1 reaches the scheduled time set by the receiving terminal 1 for both the communication 30 and the communication 31, the receiving terminal 1 can restore the receiving terminal 1 communication signal. On the other hand, the receiving terminal 2 that receives the signal from the transmitting station 501 via a propagation path different from the first propagation path 504 and the second propagation path 505 cannot synchronously receive the reception terminal 2 communication signal.
【0175】
Moreover, the correct propagation path delay time 11 and propagation path delay time 21 cannot be known in advance or measured by the receiving terminal 2. As a result, the receiving terminal 2 cannot know the arrival times of the communication 30 and the communication 31. As a result, the correct receiving terminal reference time 11 and the receiving terminal reference time 21 cannot be set for the receiving terminal 2 communication signal, and it is almost impossible to correctly receive the communication 30 and the communication 31.
【0176】
In particular, if the confidential information is distributed and transmitted to the transmission unit 502 and the transmission unit 503, a remarkable effect can be obtained in terms of security.
【0177】
Thus, according to the above configuration, in addition to the configuration of the first embodiment, a plurality of propagation paths 504 and 505 are formed by providing a plurality of transmission units 502 and 503 on the transmission side, and the respective propagation paths 504 and 505 are formed. By making the confidential information reach the predetermined time (reception terminal reference time 10, 20) of the receiving station 201 via the 505, a wireless communication system 500 with higher security can be realized.
【0178】
(Embodiment 6) In this embodiment, a configuration in which transmission data is transmitted and received at a timing that can be known only between stations communicating with each other proposed in the first embodiment and a configuration in which the transmission data is transmitted and received in the second embodiment are proposed. A configuration in which transmission data is rearranged in a known format only between stations communicating with each other, a configuration in which pseudo-symbols are mixed in the communication information proposed in the third embodiment, and a plurality of propagations proposed in the fifth embodiment. We propose a wireless communication system that combines a configuration that communicates via a road. In addition to this configuration, the wireless communication system of this embodiment is different from the fifth embodiment in that signals passing through the two propagation paths are received and synthesized at the same time. Hereinafter, the communication method of this embodiment will be described with reference to FIGS. 12 and 14.
【0179】
Here, the outline of communication 10 to communication 21 in FIG. 12 is the same as the content described in the fifth embodiment. That is, by communicating from communication 10 to communication 21, the transmitting station 501 and the receiving station 102 estimate the signal propagation time in the first and second propagation paths 504 and 505, and synchronize the operations between the two stations. Set the network reference time and the receiving terminal reference time.
【0180】
That is, first, the transmission station 501 transmits (transmission 10B) a control signal (communication 10) including the network reference time from the first transmission unit 502 while controlling the output so as to pass through the first propagation path 504. When the receiving station 102 receives the communication 10 (reception 10T), the delay time (T10) until the next transmission (transmission 20T) and the reception of the next communication 30 after a certain time (T20) are received based on that time. Set the terminal reference time 10 and so on. The receiving station 102 transmits a response signal (communication 20) to the transmitting station 501 (transmission 20T) after a delay time (T10) has elapsed from the reception 10T.
【0181】
At the same time that the transmitting station 501 receives the communication 20 (reception 20B), the propagation environment estimation unit 101c estimates the state of the first propagation path 504 from the control signal transmitted by the transmission 10B and the response signal received by the reception 20B. Specifically, the delay amount estimation unit provided in the transmitting station 501 propagates from the time of transmission 10B and reception 20B, the delay time (T10) at the reception station 102, the processing delay generated in each device, and the like. The signal propagation time on the road 504 is calculated.
【0182】
Similarly, the transmitting station 501 transmits a signal (communication 11) (transmission 11B) from the second transmitting unit 503 while controlling the output so as to pass through the second propagation path 505. When the receiving station 102 receives the communication 11 (reception 11T), the delay time (T11) until the next transmission (transmission 21T) and the reception of the next communication 31 after a certain time (T21) are received based on that time. Set the terminal reference time 20.
【0183】
In the case of this embodiment, unlike the above-described fifth embodiment, the receiving terminal reference time 20 is set to the same time as the receiving terminal reference time 10.
【0184】
The receiving station 102 transmits (transmitting 21T) a response signal (communication 21) to the transmitting station 501 after a delay time (T11) has elapsed from the receiving 20T.
【0185】
At the same time that the transmitting station 501 receives the communication 21 (reception 21B), the propagation environment estimation unit 101c receives the second propagation path from the control signal (communication 11) transmitted by the transmission 11B and the response signal (communication 21) received by the reception 21B. Estimate the state of 505. Specifically, the delay amount estimation unit provided in the transmitting station 501 propagates from the time of transmission 11B and reception 21B, the delay time (T11) at the reception station 102, the processing delay generated in each device, and the like. Calculate the signal propagation time on road 505.
【0186】
From the signal propagation time and processing delay of the first propagation path 504, the propagation environment adaptation unit 101d of the transmission station 501 transmits a signal (communication 30) to the first transmission unit 502 so as to synchronize with the reception terminal reference time 10 of the reception station 102. Transmission (transmission 30B) while controlling the output so as to pass through the first propagation path 504.
【0187】
Similarly, the propagation environment adaptation unit 101d of the transmitting station 501 sets a signal (communication 31) so as to synchronize with the receiving terminal reference time 20 of the receiving station 102 from the signal propagation time and the processing delay of the second propagation path 505. 2 Transmission (transmission 31B) is performed while controlling the output from the transmission unit 503 so as to pass through the second propagation path 505.
【0188】
Here, the communication 30 and the communication 31 include confidential information such as an encryption key. The information of the communication 30 is delayed by the time obtained by adding the signal propagation time in the first propagation path 504 to the processing delay of the transmission station 501, and is received (reception 30T) by the reception station 102. Similarly, the information of the communication 31 is also delayed by the time obtained by adding the signal propagation time in the second propagation path 505 to the processing delay, and is received (reception 31T) by the receiving station 102.
【0189】
The receiving station 102 starts receiving 30T and 31T based on the receiving terminal reference times 10 and 20. At this time, since the receiving terminal reference times 10 and 20 of the communication 30 and the communication 31 are set at the same time, the transmission data from the transmitting station 501 is received by the receiving station 102 at the same time.
【0190】
As a result, in the receiving station 102, the communication 30 and the communication 31 interfere with each other, and the combined result thereof is received in the receiving station 102. Here, the communication information of the communication 30 and the communication 31 is configured by mixing information symbols (confidential information) and pseudo symbols according to a preset format.
【0191】
First, for the sake of simplicity, it is assumed that all pseudo-symbols are zero power symbols. Of all the symbols of the communication 30, only the symbol at the time when the pseudo-symbol of the communication 31 overlaps is not interfered by the communication 31 based on the receiving terminal reference time 10 of the receiving station 102. On the contrary, among all the symbols of the communication 31, only the symbol at the time when the pseudo symbol of the communication 30 overlaps does not receive the interference of the communication 30.
【0192】
Therefore, if a format is set in advance so that the information symbols of both do not interfere with each other, a signal without deterioration due to interference can be received from both the communication 30 and the communication 31. The receiving station 102 demodulates and decodes the received signal thus synthesized.
【0193】
The communication 30 and the communication 31 of this embodiment will be described in more detail with reference to FIG. In FIG. 14, symbols 0, 3, 6, 7, and 9 and symbols B, C, E, F, and I are pseudo symbols. Further, the transmitting station 501 uses the receiving terminal 1 as the receiving station 102 of the transmitting destination, and the receiving terminal 2 serves as another terminal.
【0194】
Here, the receiving terminal reference time 10 set by the receiving station (reception terminal 1) 102 at the reception 10T and the reception 11T, and the transmission 30B and the transmission 31B whose timing is adjusted by the propagation environment adaptation unit 101d of the transmission station 501 are each propagation path 504. , 505 is almost synchronized with the time received by the receiving station 102, and communication 30 and communication 31 are received at the same time, so that the receiving terminal 1 communication signals interfere with each other.
【0195】
In FIG. 14, symbols 1, 2, 4, 5, and 8 are combined with symbols B, C, E, F, and I, respectively, and symbols A, D, G, H, and J and symbols 0, 3, 6, 7, are combined. 9 is synthesized. However, since symbols 0, 3, 6, 7, 9 and symbols B, C, E, F, and I are pseudo-symbols and their power is 0, the combined receiver 1 communication signal is A, 1. , 2, D, 4, 5, G, H, 8, J.
【0196】
Since all these information symbols are not interfered with each other by communication, communication information (confidential information) can be acquired by sequentially demodulating the received reception terminal 1 communication signal.
【0197】
On the other hand, consider a case where a third party (reception terminal 2) who is not the destination intercepts the communication 30 and the communication 31 and tries to restore the information. The receiving terminal 2 can receive communication 10, communication 11, communication 20, and communication 21, but communication 30 and communication 31 are controlled so as to be received by the receiving terminal 1 at the same time, and receive. It is received at different timings on terminal 2. Therefore, the receiving terminal 2 does not know the receiving terminal reference time 10 indicating the start of communication, and the information symbols interfere with each other, so that the confidential information cannot be restored.
【0198】
This reference time information is calculated by the receiving terminal 1 based on the reception 10T and 11T, and the transmitting station 501 uses the communication 10, 11, 20, and 21 to transmit the first and second propagation paths 504 and 505 signal propagation time (propagation). This is the target time for estimating the road delays 10 and 20) and controlling the transmission so that the signal reaches the reference time. This reference time depends on the propagation path environment (that is, the propagation path). As a result, the receiving terminal 2 cannot know the correct propagation path delay time 10 in advance or by measuring it.
【0199】
Therefore, since the receiving terminal 1 communication signal received by the receiving terminal 1 reaches the scheduled time set by the receiving terminal 1 for both the communication 30 and the communication 31, the receiving terminal 1 can restore the receiving terminal 1 communication signal. On the other hand, the receiving terminal 2 that receives the signal from the transmitting station 501 via a propagation path different from the first propagation path 504 and the second propagation path 505 cannot synchronously receive the reception terminal 2 communication signal.
【0200】
Moreover, the correct propagation path delay time 11 and propagation path delay time 21 cannot be known in advance or measured by the receiving terminal 2. As a result, the receiving terminal 2 cannot know the arrival times of the communication 30 and the communication 31. As a result, the correct receiving terminal reference time 11 cannot be set for the receiving terminal 2 communication signal, and it is almost impossible to correctly receive the communication 30 and the communication 31.
【0201】
Further, in the communication method of this embodiment, even if the receiving terminal 2 (third party) can measure the correct propagation path delay time 11 and set the correct receiving terminal reference time 11 for the communication 30 Confidential information cannot be restored. This is because, in the receiving terminal 2 located at a different location from the receiving terminal 1, the communication 31 reaches the receiving terminal 2 at a time different from the receiving terminal reference time 11. As a result, the signal of the communication 30 and the signal of the communication 31 interfere with each other at the time of reception, and the signal is deteriorated.
【0202】
In this embodiment, assuming that the communication 30 and the communication 31 arrive at the receiving station at the same time, when the head of the signal of the communication 30 and the head of the signal of the communication 31 match, the information symbols do not overlap each other. Information symbols and pseudo symbols are placed in. As a result, at the receiving station where the communication 30 and the communication 31 cannot be received at the same time, intersymbol interference occurs and the signal is deteriorated.
【0203】
Specifically, in the reception terminal 2 communication signal of FIG. 14, the information symbols 2 and A, 5 and D, 8 and G, etc. of communication 30 and communication 31 interfere with each other. As a result, the signal deteriorates due to mutual interference of the symbols, and the information symbol cannot be restored.
【0204】
Thus, according to the above configuration, the transmission timings of the two transmission units 502 and 503 of the transmission station 501 are controlled so that the two signals are received by the reception station 102 at the same time, and the signals are not received at the same time. By arranging and transmitting the information symbols (confidential information) of the two signals in a format that deteriorates due to mutual interference, the information symbols (confidential information) are sent to a location other than the location of the receiving station 102, which is the transmission target of the confidential information. It is impossible to restore the confidential information at the receiving station located. As a result, a wireless communication system with further improved security can be realized.
【0205】
(Embodiment 7) In this embodiment, in addition to the configuration of the sixth embodiment, there is a configuration in which synchronous series data is mixed with confidential information and transmitted. As the synchronous series data, for example, there is a unique word described in the first embodiment. Thereby, in this embodiment, in addition to the effect of the sixth embodiment, the reception quality at the receiving station to which the confidential information is transmitted can be improved.
【0206】
This embodiment will be described with reference to FIGS. 11, 12, and 14. The data transmitted by communication 30 and communication 31 is confidential data that is not intended to be leaked to receiving stations other than the receiving station 102, which is the transmission target of the confidential information. The symbols are arranged and configured.
【0207】
The information of the communication 30 is delayed by the time obtained by adding the signal propagation time of the first propagation path 504 to the processing delay of the transmission station 501, and is received (reception 30T) by the reception station 102 at the reception terminal reference time 10. Similarly, the information of the communication 31 is also delayed by the time obtained by adding the signal propagation time of the second propagation path 505 to the processing delay of the transmission station 501, and is received by the reception station 102 at the reception terminal reference time 10. The receiving station 102 starts receiving 30T with reference to the receiving terminal reference time 10.
【0208】
At this time, since the receiving terminal reference time 10 of the communication 30 and the communication 31 is set to the same time, the communication 30 and the communication 31 receive at the same time at the receiving station 102. Therefore, both are combined in space and received by the receiving station 102.
【0209】
On the other hand, the data of communication 30 and communication 31 has a configuration in which information symbols, pseudo symbols, and synchronization sequences are arranged according to a preset format. Here, for the sake of simplicity, it is assumed that all the pseudo symbols are symbols with zero power. Of all the symbols of the communication 30, only the symbol at the time when the pseudo-symbol of the communication 31 overlaps does not receive the interference of the communication 31 based on the receiving terminal reference time 10 of the receiving station 102. Conversely, of all the symbols of communication 31, only the symbol at the time when the pseudo-symbol of communication 30 overlaps does not receive the interference of communication 30.
【0210】
In this way, assuming that the transmitting station 501 receives two signals from the communication 30 and the communication 31 at the same time in advance, the format is set so that the two do not interfere with each other, so that the communication 30 and the communication 31 are not interfered with each other. The receiving station 102 that receives the above signals at the same time can receive a signal that is not deteriorated due to the interference of both signals.
【0211】
Upon receiving these signals, the receiving station 102 first synchronizes the time, frequency, phase, etc. with respect to the symbol of the communication 30 using the synchronization sequence of the communication 30, and demodulates the information symbol of the communication 30. Similarly, the receiving station 102 synchronizes the time, frequency, phase, etc. with respect to the symbol of communication 31 by using the synchronization sequence of communication 31, and demodulates the information symbol of communication 31.
【0212】
Next, the two demodulated information symbols are combined and decoded. After that, the transmitting station 501 and the receiving station 102 perform communication after communication 4 while performing encryption and encryption / decryption based on the information (for example, encryption key) transmitted in communication 30 and communication 31.
【0213】
The communication 30 and the communication 31 of this embodiment will be described in more detail with reference to FIG. In FIG. 14, symbols 0, 3, 6, 7, 9 and symbols B, C, E, F, and I are pseudo-symbols, symbols 1 and 8 and symbols A and G are synchronous series, and symbols 2 and 4 are used. , 5, D, H, J are information symbols.
【0214】
Here, the receiving terminal (reception terminal 1) 102 sets the receiving terminal reference time 10 for reception 10T and reception 11T, and the transmission 30B and transmission 31B adjusted by the propagation environment adaptation unit 101d of the transmission station 501 are each propagation path 504. It is almost synchronized with the times of reception 30T and reception 31T received by the receiving station 102 via 505. As a result, since the communication 30 and the communication 31 are received at the same time, they interfere with each other in the reception terminal 1 communication signal.
【0215】
In FIG. 14, the symbols 1, 2, 4, 5, and 8 are combined with the symbols B, C, E, F, and I, respectively, and the symbols A, D, G, H, and J and the symbols 0, 3, and 6 are combined. , 7, 9 are combined, but symbols 0, 3, 6, 7, 9 and symbols B, C, E, F, I are pseudo-symbols, and their power is 0, so the combined receiving end One communication signal is A, 1, 2, D, 4, 5, G, H, 8, J.
【0216】
Since all the information symbols and the synchronization series are not interfered with each other by communication in this way, the communication information including the confidential information can be restored by sequentially demodulating the received reception terminal 1 communication signal.
【0217】
Thus, according to the above configuration, in addition to the configuration of the sixth embodiment, the synchronous series data is mixed in the transmission data including the confidential information, so that the reception can be performed in addition to the effect of the sixth embodiment. The station 102 can realize a wireless communication system that can further improve the reception quality.
【0218】
(Embodiment 8) In FIG. 15, 800 indicates the wireless communication system according to the eighth embodiment of the present invention as a whole. The wireless communication system 800 has first and second transmission stations 801 and 802, and the transmission stations 801 and 802 are connected to the network 805 via the network connection portions 803 and 804. Further, the first transmitting station 801 communicates with the receiving station 102 via the first propagation path 806, and the second transmitting station 802 communicates with the receiving station 102 via the second propagation path 807.
【0219】
Here, the configurations of the first and second transmitting stations 801 and 802 are substantially the same as those of the transmitting station 101 described in the first embodiment except that the network connecting portions 803 and 804 are provided. Further, the receiving station 102 has substantially the same configuration as the receiving station 102 described in the first embodiment except that it communicates with the second transmitting station 802 in addition to the first transmitting station 801.
【0220】
Further, the first and second transmitting stations 801, 802 transmit the transmission data including the confidential information at the timing when the receiving terminal reference time set by the receiving station is reached, and as described in the sixth embodiment, each other. The transmission data of the above is transmitted at the timing so as to reach the same receiving terminal reference time.
【0221】
That is, when the wireless communication system 800 of this embodiment is compared with the wireless communication system described in the sixth embodiment, the wireless communication system of the sixth embodiment is a receiving station 102 from the same transmitting station via different propagation paths. The wireless communication system 800 differs in that it transmits information from different transmitting stations 801 and 802 to receiving station 102 via different propagation paths 806 and 807.
【0222】
Here, the communication 800 of the wireless communication system is performed by the communication procedure as shown in FIG. 16 via the first propagation path 806 and the second propagation path 807.
【0223】
The first transmission station 801 transmits (transmission 10B) a control signal (communication 10) including a network reference time from the transmission unit 101a while controlling the output so as to pass through the first propagation path 806. When the receiving station 102 receives the communication 10 (reception 10T), the receiving station 102 sets a predetermined delay time (T10) controlled by the time control unit 102c. The receiving station 102 transmits a response signal (communication 20) to the first transmitting station 801 (transmission 20T) after a delay time (T10) has elapsed from the reception 10T.
【0224】
Incidentally, the transmitting station 801 and the receiving station 102 each hold the delay time T10 as shared information in advance.
【0225】
At the same time that the first transmitting station 801 receives the communication 20 (reception 20B), the propagation environment estimation unit 101c from the control signal (communication 10) transmitted by the transmission 10B and the response signal received by the reception 20B determines the first propagation path 806. Estimate the state. Specifically, the propagation environment estimation unit 101c provided in the transmitting station 801 is based on the time of transmission 10B and reception 20B, the delay time (T10) at the reception station 102, the processing delay generated in each device, and the like. The signal propagation time in the first propagation path 806 is calculated.
【0226】
Similarly, the second transmission station 802 transmits (transmission 11B) a control signal (communication 11) including the network reference time from the transmission unit 101a while controlling the output so as to pass through the second propagation path 807. When the receiving station 102 receives the communication 11 (reception 11T), the receiving station 102 sets a predetermined delay time (T11) controlled by the time control unit 102c. The receiving station 102 transmits (transmitting 21T) a response signal (communication 21) to the second transmitting station 802 after a delay time (T11) has elapsed from the receiving 11T.
【0227】
Incidentally, the transmitting station 802 and the receiving station 102 each hold the delay time T11 as shared information in advance.
【0228】
At the same time that the second transmitting station 802 receives the communication 21 (reception 21B), the propagation environment estimation unit 101c from the control signal (communication 11) transmitted by the transmission 11B and the response signal received by the reception 21B determines the second propagation path 807. Estimate the state. Specifically, the propagation environment estimation unit 101c provided in the transmission station 802 is based on the time of transmission 11B and reception 21B, the delay time (T11) at the reception station 102, the processing delay generated in each device, and the like. The signal propagation time in the second propagation path 807 is calculated.
【0229】
As described above, after the estimation of the signal propagation time between the first transmitting station 801 and the receiving station 102 and the signal propagation time between the second transmitting station 802 and the receiving station 102 is completed, the receiving station 102 then sets the time control unit 102c. Is used to set the receiving terminal reference signal 10 after a certain time (T20), and transmit (transmit 30T) the reference time notification signal (communication 30) to the first transmitting station 801 and the second transmitting station 802. ..
【0230】
The first transmitting station 801 acquires the confidential information to be transmitted to the receiving station 102 from the network 805 via the network connection unit 803. Similarly, the second transmitting station 802 acquires the confidential information to be transmitted to the receiving station 102 from the network 805 via the network connection unit 804.
【0231】
When the first transmitting station 801 receives the communication 30 (reception 30B), the propagation environment adaptation unit 101d of the first transmitting station 801 receives the signal from the signal propagation time of the first propagation path 806, the processing delay, and the time of the reception 30B. The transmission timing of the communication 40 is controlled so that the reception terminal reference time 10 of the station 102 is reached. Then, the first transmission station 801 transmits a signal (communication 40) from the transmission unit 101a so as to pass through the first propagation path 806 (transmission 40B).
【0232】
Similarly, when the second transmission station 802 receives the communication 30 (reception 31B), the propagation environment adaptation unit 101d of the second transmission station 802 sets the signal propagation time of the second propagation path 807, the processing delay, and the time of the reception 31B. Therefore, the transmission timing of the communication 40 is controlled so that the reception terminal reference time 10 of the reception station 102 is reached. Then, the second transmission station 802 transmits a signal (communication 41) from the transmission unit 101a so as to pass through the second propagation path 807 (transmission 41B).
【0233】
The information of the communication 40 is delayed by the time obtained by adding the signal propagation time of the first propagation path 806 to the processing delay of the first transmission station 801 and is received (reception 40T) by the reception station 102 at the reception terminal reference time 10. .. Similarly, the information of the communication 41 is also delayed by the time obtained by adding the signal propagation time of the second propagation path 807 to the processing delay of the second transmission station 802, and is received by the reception station 102 at the reception terminal reference time 10. The receiving station 102 starts receiving 40T with reference to the receiving terminal reference time 10.
【0234】
At this time, since the receiving terminal reference time 10 of the communication 40 and the communication 41 is set to the same time, the receiving station 102 receives the communication 40 and the communication 41 at the same time. That is, both are received by the receiving station 102 as a result of being combined.
【0235】
Here, when the data transmitted by the communication 40 and the communication 41 are received at the same time as the transmission data of the seventh embodiment, the information symbol, the pseudo symbol, and the synchronization series symbol interfere with each other. They are arranged so that they do not conflict with each other. As a result, as in the seventh embodiment, the contents of the communication 40 and the communication 41 can be demodulated and decoded only by the receiving station 102. By the way, if the first half of the communication 40 is set as a pseudo symbol and the second half of the communication 41 is set as a pseudo symbol (or the arrival times of the communication 40 and the communication 41 are provided at regular intervals), the receiving station 102 is the first. And the information from the second receiving stations 801 and 802 can be continuously received.
【0236】
Thus, according to the above configuration, the confidential information is divided into a plurality of information blocks, the divided confidential information is distributed to a plurality of transmitting stations using a highly secure communication line such as a dedicated line, and the distributed confidential information is distributed. By transmitting to the receiving station, it is possible to realize a wireless communication system 800 capable of transmitting confidential information with higher security.
【0237】
(Embodiment 9) In FIG. 17, which is shown by assigning the same reference numerals to the portions corresponding to those in FIG. 1, 900 indicates the wireless communication system according to the ninth embodiment of the present invention as a whole. The wireless communication system 900 has first and second transmission / reception units 902 and 903 including the transmission unit 101a and the reception unit 101b described above in FIG. 1, respectively. Then, the first transmission / reception unit 902 communicates with the receiving station 102 via the first propagation path 906, and the second transmission / reception unit 903 communicates with the reception station 102 via the second propagation path 907.
【0238】
Here, in the communication operation between the transmitting station 901 and the receiving station 102, as will be described later, the receiving power received by the transmitting station 901 via the first and second propagation paths 906 and 907 is estimated, and the estimated power is estimated. This is the same as the wireless communication system 500 of the fifth embodiment described with reference to FIG. 11, except that the transmission power is controlled according to the above and a signal is transmitted to the receiving station 102.
【0239】
Here, FIG. 18 shows a detailed configuration of the transmitting station 901 according to this embodiment. In FIG. 18, the parts corresponding to those in FIG. 2 are designated by the same reference numerals. In the case of this embodiment, the propagation environment estimation unit 904 is composed of a delay amount estimation unit 904a and a power measurement unit 904b. The propagation environment adaptation unit 905 is composed of a timing control unit 905a and a power control unit 905b.
【0240】
Then, a known signal such as a unique word extracted by the demodulation unit 122 of the first transmission / reception unit 902 is input to the delay amount estimation unit 904a, and is extracted by the demodulation unit (not shown) of the second transmission / reception unit 903. A known signal such as a unique word is input to the delay amount estimation unit 904a. As described in the first embodiment, the delay amount estimation unit 904a estimates the signal propagation time from the network time and the known signal. In the case of this embodiment, the signal propagation times of the first and second propagation paths 906 and 907 are estimated.
【0241】
Then, the timing control unit 905a considers the signal propagation time of the first propagation path 906 obtained by the delay amount estimation unit 904a, and the signal from the first transmission / reception unit 902 is predetermined via the first propagation path 906. The output timing of the buffer 117 is adjusted so that the receiving station 102 is reached at the network time.
【0242】
Similarly, the timing control unit 905a determines in advance the signal from the second transmission / reception unit 903 via the second propagation path 907 in consideration of the signal propagation time of the second propagation path 907 obtained by the delay amount estimation unit 904a. The output timing of the buffer (not shown) is adjusted so that the receiving station 102 is reached at the specified network time.
【0243】
The power measurement unit 904b of the propagation environment estimation unit 904 inputs the output of the radio reception unit (reception RF) 121 of the first transmission / reception unit 902, and measures the power of the reception signal received by the first transmission / reception unit 902. Similarly, the power measuring unit 904b inputs the output of the wireless receiving unit (not shown) of the second transmitting / receiving unit 903, and measures the power of the received signal received by the second transmitting / receiving unit 903.
【0244】
The power control unit 905b of the propagation environment adaptation unit 905 compares the preset power value with the received power measurement result obtained by the power measurement unit 904b, and based on the comparison result, the first and second transmission / reception stations. Controls the transmission power of 902 and 903. Specifically, when the received power received by the first or second transmission / reception units 902 and 903 is smaller than a predetermined value, the transmission power is increased by controlling the radio transmission unit (transmission RF) 119 of each transmission unit 101a. Control to increase. On the contrary, when the received power received by the first or second transmission / reception units 902 and 903 is larger than the predetermined value, the radio transmission unit (transmission RF) 119 of each transmission unit 101a is controlled to transmit. Control so that the power is small.
【0245】
As a result, in the wireless communication system 900, only the receiving station 102, which is the transmission target of the confidential information, can receive the optimum receiving signal of the receiving level from the first transmitting / receiving section 902 and the second transmitting / receiving section 903 of the transmitting station 901. ..
【0246】
As a result, the receiving station 102 can obtain a composite result of two signals whose reception levels are optimally adapted to the propagation paths 906 and 906 and reach the same time in synchronization with the reception operation. As a result, the receiving station 102 can reliably demodulate the confidential information.
【0247】
On the other hand, since the third party receives the information from the transmitting station 901 at a place different from the receiving station 102, it is difficult to obtain an appropriate reception level and an appropriate reception timing for demodulating the signal. Therefore, it becomes difficult to demodulate the received signal.
【0248】
Next, the operation of the wireless communication system 900 will be described with reference to FIGS. 14 and 16.
【0249】
First, the transmission station 901 transmits (transmission 10B) a signal (communication 10) including a network reference time from the first transmission unit 902 while controlling the output so as to pass through the first propagation path 906. When the receiving station 102 receives the communication 10 (reception 10T), the receiving station 102 sets a predetermined delay time (T10) controlled by the time control unit 102c. The receiving station 102 transmits a response signal (communication 20) to the transmitting station 901 with a predetermined power (transmission 20T) after a delay time (T10) has elapsed from the receiving 10T. Incidentally, the transmitting station 901 and the receiving station 102 each hold the delay time T10 as shared information in advance.
【0250】
At the same time that the transmitting station 901 receives the communication 20 (reception 20B), the propagation environment estimation unit 904 is the first from the propagation path estimation signal (communication 10) transmitted by the transmission 10B and the response signal (communication 20) received by the reception 20B. 1 Estimate the state of propagation path 906. Specifically, the signal propagation time and power attenuation in the first propagation path 906 are estimated. The power attenuation in the propagation path 906 is estimated by measuring the power of the received 20B and based on the difference between the value and the output power of the predetermined response signal (communication 20).
【0251】
Similarly, the transmission station 901 transmits (transmission 11B) a signal (communication 11) including the network reference time from the second transmission unit 903 while controlling the output so as to pass through the second propagation path 907. When the receiving station 102 receives the communication 11 (reception 11T), the receiving station 102 sets a predetermined delay time (T11) controlled by the time control unit 102c. The receiving station 102 transmits a response signal (communication 21) to the transmitting station 901 with a predetermined power (transmission 21T) after a delay time (T11) has elapsed from the receiving 11T. Incidentally, the transmitting station 901 and the receiving station 102 each hold the delay time T11 as shared information in advance.
【0252】
At the same time that the transmitting station 901 receives the communication 21 (reception 21B), the propagation environment estimation unit 904 is the first from the propagation path estimation signal (communication 11) transmitted by the transmission 11B and the response signal (communication 21) received by the reception 21B. 2 Estimate the state of propagation path 907. Specifically, the signal propagation time and power attenuation in the second propagation path 907 are estimated. The power attenuation in the propagation path 907 is estimated by measuring the power of the reception 21B and based on the difference between the value and the output power of the predetermined response signal (communication 21).
【0253】
In this way, the transmitting station 901 estimates the signal propagation time and the signal power attenuation in the first and second propagation paths 906 and 907 based on the communication 30 and the communication 31.
【0254】
The receiving station 102 sets the receiving terminal reference signal 10 after a certain time (T20) using the time control unit 102c, and transmits (transmits 30T) the reference time notification signal (communication 30) to the transmitting station 901.
【0255】
Next, the transmission station 901 transmits a signal containing confidential information from the first transmission / reception unit 902 via communication 40 (transmission 40B), and transmits a signal containing confidential information from the second transmission / reception unit 903 via communication 41 (transmission 41B). To do. At this time, the transmitting station 901 controls the transmission timing so that the two signals arrive at the receiving terminal reference time 10 set by the receiving station 102 at the same time, and the receiving station 102 can receive the two signals with the optimum power. The transmission power is controlled so as to.
【0256】
The receiving station 102 starts receiving 40T with reference to the receiving terminal reference time 10. At this time, since the receiving terminal reference time 10 of the communication 40 and the communication 41 is set to the same time, the receiving station 102 receives the communication 40 and the communication 41 at the same time. That is, both are received by the receiving station 102 as a result of being combined.
【0257】
In the case of this embodiment, the same information is transmitted in communication 40 and communication 41. As a result, the receiving station 102 can obtain the path diversity effect. Further, in the case of this embodiment, the transmitting station 901 transmits the communication 40 and the communication 41 with very low power. As a result, the receiving station 102, which can synthesize and receive the same symbols of two signals, can obtain a signal level sufficient for demodulation, whereas other receiving stations located at different locations from the receiving station 102. Then, the signal level required for demodulation cannot be obtained from communication 40 and communication 41.
【0258】
Thus, according to the above configuration, by providing a plurality of transmission / reception units 902 and 903 in the transmission station 901, a plurality of propagation paths 906 and 907 are formed between the transmission station 901 and the reception station 102, and each propagation path 906, The lowest level of transmission power that can be demodulated when the receiving station 102 synthesizes and receives each received signal that arrives through multiple propagation paths 906 and 907 by estimating the amount of power attenuation when communicating with the 907. Since the confidential information is transmitted from the plurality of transmission / reception units 902 and 903, it becomes difficult for other receiving stations located at locations other than the receiving station 102 to demodulate the confidential information. As a result, it is possible to realize a wireless communication system 900 capable of performing communication with higher security.
【0259】
(Embodiment 10) In FIG. 19, 1000 indicates a wireless communication system according to the tenth embodiment of the present invention as a whole. The transmitting station 1001 of the wireless communication system 1000 has an antenna unit 1003 composed of two linearly polarized antennas AN20 and AN21 whose planes of polarization are orthogonal to each other. Further, the antenna unit 1004 of the receiving station 1002 has one linearly polarized antenna AN30.
【0260】
As a result, in the wireless communication system 1000, the plane of polarization of the antenna AN30 of the receiving station 1002 is received from the transmitting station 1001 in consideration of this propagation path environment as a propagation path environment shared only by the transmitting station 1001 and the receiving station 1002. Confidential information is transmitted to station 1002.
【0261】
That is, first, the propagation environment estimation unit 1006 of the transmission station 1001 estimates the polarization plane of the antenna AN30 of the reception station 1002 based on the transmission wave transmitted from the reception station 1002. Next, based on the estimation result obtained by the propagation environment estimation unit 1006, the antenna unit 1003 is controlled so that the radiation characteristic control unit 1008 of the transmission station 1001 forms radiation characteristics that can be received only by the reception station 1002. It has become.
【0262】
Further, the transmitting station 1001 and the receiving station 1002 of the wireless communication system 1000 are provided with time control units 1007 and 1010, and the time control units 1007 and 1010 provide the transmitting station 1001 and the receiving station 1002 as in the first embodiment. Confidential information is transmitted from the transmitting station 1001 to the receiving station 1002 at the transmission timing in consideration of the signal propagation time on the propagation path 1011 that can be shared only by. As a result, only the receiving station 1002 can receive and restore the confidential information.
【0263】
Therefore, the time control unit 1007 in FIG. 19 corresponds to the propagation environment estimation unit 101c and the propagation environment adaptation unit 101d in FIG. Since the receiving station 1002 has the same configuration as that in FIG. 3, detailed description thereof will be omitted here. Briefly, the antenna AN30 corresponds to the antenna AN12, the transmission / reception unit 1009 corresponds to the transmission unit 102a and the reception unit 102b, and the time control unit 1010 corresponds to the time control unit 102c.
【0264】
The specific configuration of the transmitting station 1001 is shown in FIG. In FIG. 20, which is shown by assigning the same reference numerals to the portions corresponding to those in FIG. 2, the transmitting station 1001 is roughly divided into a transmitting unit 1012, a receiving unit 1013, a propagation environment estimation unit 1006, and a time control unit 1007. .. Here, the transmission / reception unit 1005 in FIG. 19 corresponds to the transmission unit 1012 and the reception unit 1013.
【0265】
The transmitting station 1001 receives radio waves from the receiving station 1002 by two linearly polarized antennas AN20 and AN21 provided so that their polarization planes are orthogonal to each other. Then, each antenna output is input to the wireless receiver (reception RF) 121. The wireless receiving unit 121 performs wireless processing such as down-conversion and analog-digital conversion processing on each antenna output, and sends the processed signal to the demodulation unit 122 and the propagation environment estimation unit 1006.
【0266】
The propagation environment estimation unit 1006 estimates the polarization plane of the antenna of the receiving station 1002 based on the two antenna outputs processed by wireless communication, and sends the estimation result to the radiation characteristic control unit 1008. Based on the estimation result, the radiation characteristic control unit 1008 controls the radio transmission unit (transmission RF) 119 so that the reception power at the reception station 1002 is maximized.
【0267】
The propagation environment estimation unit 1006 is configured as shown in FIG. The radiation characteristic control unit 1008 is configured as shown in FIG.
【0268】
The propagation environment estimation unit 1006 has an electric field strength detection unit 1020 and a phase difference detection unit 1021. The electric field strength detection unit 1020 detects the electric field strength of each antenna output based on the two antenna outputs. Further, the phase difference detection unit 1021 obtains the phase difference of each antenna output based on the two antenna outputs. The polarization estimation unit 1022 estimates the polarization state of the received signal from the electric field strength and phase difference between the two antenna outputs.
【0269】
Generally, when two antennas (V, H) whose planes of polarization are orthogonal to each other are used, as shown in FIG. 23, the polarization of the electromagnetic wave (p in the figure) is the plane of polarization given by the radiation characteristics of the antenna (in the figure). It can be obtained from the electric field strength (Ev, Eh in the figure) projected on V, H) and the phase difference between both received signals. For example, with polarized light p as elliptically polarized light, the angle and flatness of the long axis and the antenna (V, H) can be obtained using the electric field strength (Ev, Eh) and the phase difference φ. The angle can also be approximated from Ev and Eh.
【0270】
The propagation environment estimation unit 1006 of this embodiment uses this to estimate the polarization state consisting of information such as the angle between the long axis of the polarization p and the antenna and the flatness. There is.
【0271】
As shown in FIG. 22, the radiation characteristic control unit 1008 inputs the transmission signal and the estimation value signal obtained by the polarization estimation unit 1022 to the electric field strength control unit 1030 and the phase control unit 1031, respectively. The synthesizer 1032 generates signal vectors (V vector, H vector) corresponding to antennas AN20 and AN21 that are orthogonal to each other from the electric field strength and the phase. Then, the transmission signal according to the amplitude and phase of the V direction vector is output to the V direction antenna AN21 via the radio transmission unit 119, and the transmission signal according to the amplitude and phase of the H direction vector is output via the radio transmission unit 119. Output to H direction antenna AN20.
【0272】
As a result, based on the polarization state estimated by the propagation environment estimation unit 1020, the long axis of the polarization p and the radiation characteristics of the antenna are maximized so that the reception power at the antenna unit 1004 of the receiving station 1002 is maximized. The polarization plane of the transmitted signal can be controlled so as to coincide with the axis of the polarization plane given in.
【0273】
Next, the operation of the wireless communication system 1000 will be described with reference to FIG. 24. Here, since the transmission / reception timing between the transmitting station 1001 and the receiving station 1002 is the same as that in the first embodiment, only the point of adjusting the polarization plane of the radio wave will be described.
【0274】
First, the receiving station 1002 transmits (transmits 1T) a polarization estimation signal (communication 1). Here, since the antenna unit 1004 of the receiving station 1002 is composed of the antenna AN30 having the characteristic of linearly polarized waves as the radiation characteristic, the electromagnetic wave transmitted by the antenna AN30 has a specific plane of polarization.
【0275】
This transmission signal is received by the antenna unit 1003 of the transmission station 1001 in a state where the plane of polarization is rotated by reflection or diffraction on the propagation path 1011 and a delay is added. Since the antennas AN20 and AN21 having linearly polarized radiation characteristics are arranged in the antenna unit 1003 of the transmitting station 1001 so that the planes of polarization are orthogonal to each other, stable reception is performed regardless of the plane of polarization of the received signal. be able to.
【0276】
When the transmitting station 1001 receives communication 1 by the antenna unit 1003 (reception 1B), the propagation environment estimation unit 1006a estimates the polarization state of the received signal by arithmetically processing each received signal received by the two antennas AN20 and AN21. To do.
【0277】
Next, the radiation characteristic control unit 1008 maximizes the received power at the antenna unit 1004 of the receiving station 1002 based on the polarization state estimated by the propagation environment estimation unit 1006, that is, the long axis of the polarization p and the antenna. Communication 2 is transmitted (transmission 2B) by controlling the polarization plane of the transmission signal so that the axis of the polarization plane given by the radiation characteristics of AN30 coincides. This control of the plane of polarization can be realized by performing an operation opposite to the estimation method at the time of reception.
【0278】
When the polarization plane is controlled and the transmission signal is output in this way, the antenna unit 1004 of the reception station 1002 can receive the signal of communication 2 from the transmission station 1001 on the optimum polarization plane. The receiving station 1002 receives communication 2 (received 2T) by the antenna unit 1004. Incidentally, the transmitting station 1001 transmits the transmission data including the confidential information to the receiving station 1002 by the communication 2. After that, the wireless communication system 100 performs communication 3 or later between the transmitting station 1001 and the receiving station 1002 in the same manner.
【0279】
Here, when the transmitting station 1001 and the receiving station 1002 communicate in an environment with good visibility, the plane of polarization is kept stable, so that the communication according to this embodiment can be performed stably. On the other hand, in an environment where there is an obstacle between the two communication paths and communication cannot be performed only by direct waves, the plane of polarization is disturbed due to the influence of the surrounding conditions. However, if the interval between the time when the propagation path environment (corresponding to the plane of polarization in this embodiment) is estimated and the time when communication is actually performed using the propagation path environment is sufficiently short, the propagation path environment is quasi-static. There is no problem because it can be regarded as.
【0280】
For example, both the transmitting station 1001 and the receiving station 1002 are fixed, and this corresponds to the case where an obstacle having a low moving speed such as a person exists on the communication path between the two stations. Also, for example, when the transmitting station 1001 is placed on the road and the receiving station 1002 is mounted on a car, even if there is no obstacle between the communication paths of the transmitting station 1001 and the receiving station 1002, it is biased due to changes in the situation. This is equivalent to this because the wave surface is disturbed.
【0281】
In these cases, even if one or both of the transmitting station 1001 and the receiving station 1002 are moving, the interval between the time when the propagation path environment is estimated and the time when communication is actually performed using the propagation path environment is sufficient. The propagation path environment can be considered quasi-static because it can be considered short.
【0282】
On the other hand, consider a case where a third party who is not a legitimate communication partner intercepts communication 1 and communication 2 and tries to extract information. In this case, in order for an unjust receiving terminal to receive the information of communication 2, it is necessary to appropriately align the planes of polarization.
【0283】
The transmitting station 1001 and the receiving station 1002 align the planes of polarization by communication 1, but since communication 1 is an output signal from the receiving station 1002, an unjust receiving terminal detects the plane of polarization from the transmitting station 1001. It cannot be estimated. That is, since the polarization state of communication 2 at the antenna end of the receiving station 1002 cannot be known in advance, it is impossible to intercept this.
【0284】
As a result, even if an unjust receiving station can intercept the communication 1, the communication 2 is controlled and transmitted according to the plane of polarization in the communication 1, so that the unjust receiving station outputs from the transmitting station 1001. It is not possible to know in advance the plane of polarization of the electromagnetic waves to be generated.
【0285】
This will be described in detail with reference to FIG. 25. Communication 1 and communication 2 in FIG. 25 are the same as those in FIG. 24. Further, in FIG. 25, the receiving station 1040 indicates an unjust receiving station that is not a transmission target of confidential information.
【0286】
Here, the transmitting station 1001 and the receiving station 1002 perform communication 1 and communication 2 via the propagation path 1011. Consider the case where an unjust receiving station 1040 receives these communications 1 and 2. Between the transmitting station 1001 and the receiving station 1002, both communication 1 and communication 2 are performed via the propagation path 1011. On the other hand, in the receiving station 1040, the communication 1 is received via the propagation path 1041, and the communication 2 is received via the propagation path 1042.
【0287】
In this way, the propagation path 1041 when the receiving station 1040 receives the communication 1 output by the receiving station 1002 and the propagation path 1042 when the receiving station 1040 receives the communication 2 output by the transmitting station 1001 are the propagation paths. Different from 1011. As a result, even if the receiving station 1040 can estimate the propagation path 1041 formed with the receiving station 1002 by intercepting the communication 1, this propagation path 1041 is formed with the transmitting station 1001. Communication 2 cannot be received correctly because it is different from the propagation path 1042. Therefore, it is impossible for an unjust receiving station 1040 to stably obtain information on either communication 1 or communication 2, or both.
【0288】
Generally, in a wireless communication system using electromagnetic waves, it is necessary to match the polarization characteristics of an antenna or the like between the transmitting side and the receiving side, and if this is not done correctly, characteristics such as communication quality will deteriorate. For example, if the polarization characteristics of the antenna's radiation characteristics are uniform with respect to the horizontal direction, both the transmitting station and the receiving station have the polarization planes so that the polarization planes of the antenna's radiation characteristics are perpendicular to the ground plane. You just have to make adjustments. In the case of vertically polarized waves with the plane of polarization perpendicular to the ground surface, it is easy to design the radiation characteristics uniformly in the horizontal direction.
【0289】
On the other hand, if the radiation characteristics of the antenna are not uniform in the horizontal direction, it is necessary to adjust the plane of polarization between the transmitting station and the receiving station. This will be specifically described with reference to FIGS. 26 and 27. In a wireless communication system in which electromagnetic waves propagate in a direction parallel to the ground surface direction, as shown in FIG. 26 (a), by arranging the antenna ANs of the transmitting device and the receiving device perpendicular to the ground plane, The radiation characteristics of the antenna AN can be set to vertically polarized waves. Here, it is assumed that the ground plane is kept almost horizontal, and that the radiation characteristics in the horizontal direction are uniform.
【0290】
Next, as shown in Fig. 26 (b), consider a specific example when the antenna AN is installed in the horizontal direction. Assuming that the antenna in the figure is a dipole antenna, the radiation characteristics are not uniform in the horizontal direction, and the plane of polarization also differs depending on the positional relationship with the device main body 1050. Consider, for example, a system that transmits radio waves in the height direction with such a configuration.
【0291】
It is assumed that 1050 in FIG. 27 is a transmitting device and 1051 and 1052 are receiving devices, and that the radiation characteristics of the antennas of the respective devices 1050, 1051 and 1052 are in the direction of the arrow in the figure. Here, the transmitting device 1050 is replaced with the transmitting station 1001 and the receiving device 1052 is replaced with the receiving station 1002, the transmitting device 1050 estimates the polarization plane of the receiving device 1052, and the polarization plane of the transmitting device 1050 is controlled from the estimation result. , This applies to the wireless communication system 1000 of this embodiment.
【0292】
As shown in Fig. 27, even if the ground plane of the receiver 1052 is kept horizontal with respect to the plane of polarization of the transmitter 1050, the communication environment differs greatly depending on the situation because there is a degree of freedom when viewed from the plane of polarization. Come on.
【0293】
Therefore, when the planes of polarization are aligned on the same axis as in the transmitting device 1050 and the receiving device 1052, the receiving device 1052 can receive with high sensitivity, but the plane of polarization is orthogonal to the transmitting device 1050 like the receiving device 1051. If they are arranged, the reception power will not be sufficient due to the radiation characteristics of the antenna, and the reception quality will deteriorate.
【0294】
Here, the description is made on the assumption that the plane of polarization does not rotate in the radio propagation path between transmission and reception, but it is known that the axis of the plane of polarization changes due to reflection or the like. Even in such a case, the same can be said about the plane of polarization at the antenna end of each device. Even in such a state, according to the configuration of this embodiment, the polarization planes on the transmitting side and the receiving side are adjusted in order to control the transmitted wave so that the transmitting device 1101 has the same polarization plane as the receiving device 1102. Stable communication can be performed without doing anything.
【0295】
Further, a case where a third party attempts to intercept the communication between the transmitting device 1050 and the receiving device 1052 using the receiving device 1051 will be described. As described above, it is necessary to install the plane of polarization of the receiving device 1051 according to the plane of polarization transmitted from the transmitting device 1050 so that the reception condition is improved. However, since the plane of polarization of the transmitted wave is controlled by adapting to the plane of polarization of the receiving device 1052, it cannot be known from the receiving device 1051.
【0296】
Further, as described above, since the plane of polarization differs depending on the installation direction of the receiving device 1052, it is impossible to always know it. Even if the state of the plane of polarization is estimated from the installation status of the receiver 1052, the propagation path between the transmitter 1050 and the receiver 1052 and the propagation path between the transmitter 1050 and the receiver 1051 are different. It is impossible to know the correct state. Therefore, it is impossible for a third party to intercept the communication between the transmitting device 1050 and the receiving device 1052.
【0297】
Further, as described above, when a phenomenon such as reflection or diffraction occurs on the propagation path, the plane of polarization of the electromagnetic wave changes, so that it is difficult for a third party to estimate the plane of polarization. Environments where reflections and diffractions occur frequently are well known indoors, indoors, and places such as offices with many obstacles such as partitions.
【0298】
Incidentally, in the case of this embodiment, the transmitting station 1001 transmits the linearly polarized electromagnetic wave having the optimum plane of polarization with respect to the antenna AN30 of the receiving station 1002 by superimposing the true information including the secret information on it. It is also conceivable to superimpose pseudo information on a linearly polarized electromagnetic wave having a plane of polarization parallel to an orthogonal axis and transmit it.
【0299】
As a result, in the wireless communication system 1000, the receiving station 1002 normally receives the true information due to the characteristics of the antenna AN30, but does not receive the pseudo information. As a result, only true information can be selectively received without using a complicated configuration.
【0300】
That is, the receiving station 1002 does not need to know in advance which signal is confidential information and which signal is pseudo information. Further, the transmitting station 1001 can freely conceal the data without performing a data arrangement in consideration of data separation on the receiving side. Furthermore, since the third party cannot separate the confidential information and the pseudo information in principle, high security can be ensured.
【0301】
The wireless communication system 1000 performs communication after communication 3 while matching the planes of polarization in the same manner as communication 1 and communication 2 described above. Incidentally, in communication 3 or later, all transmission data may be transmitted with the planes of polarization aligned, but after transmitting only particularly important confidential information such as an encryption key with the planes of polarization aligned, it is normal. It may be transmitted only by performing encryption processing.
【0302】
Thus, according to the above configuration, in addition to the configuration of the first embodiment, the polarization plane of the antenna AN30 of the receiving station 1002 is determined by the propagation environment estimation unit 1006 of the transmitting station 1001 based on the transmission wave transmitted from the receiving station 1002. Is estimated, and based on the estimation result, a transmission wave having radiation characteristics that can be received only by the reception station 1002 is formed, and confidential information is superimposed on the transmission wave and transmitted to the reception station 1002. By doing so, in addition to the effect of the first embodiment, the wireless communication system 1000 with higher security can be realized.
【0303】
Incidentally, in this embodiment, vertically polarized waves and horizontally polarized waves are taken as examples, but considering the plane of polarization inclined at a certain angle with respect to the ground surface, it becomes more difficult for a third party to receive confidential information. For example, when a dipole antenna with linearly polarized characteristics is installed at a certain angle with respect to the ground surface, the radiation characteristics of the antenna differ with respect to the horizontal direction as described above, and the radiation characteristics depend on the apparent angle of the antenna. Change. That is, the radiation characteristics change depending on the relative positional relationship between the transmitting device 1050 and the receiving device 1052 shown in FIG. 27. As a result, it becomes more difficult to estimate the plane of polarization from a third party.
【0304】
Further, the plane of polarization can be electrically controlled by controlling the amplitude and phase of the radiation signal to the plane of polarization using an antenna such as a helical antenna having orthogonal polarization plane characteristics. With such a configuration, it becomes difficult to visually estimate the plane of polarization, and a system with even higher security can be realized.
【0305】
Furthermore, in the above description, the case where the transmitting station 1001 outputs a linearly polarized electromagnetic wave having an optimum polarization plane to the antenna AN30 of the receiving station 1002 from the beginning has been described, but the receiving station 1002 is like when the power is turned on. Until the characteristics of the antenna AN30 of the above are estimated, an electromagnetic wave having a circularly polarized wave may be emitted from the transmitting station 1001. In this way, the receiving station 1002 can stably receive a signal for establishing a wireless link such as RACH (Random Access Channel) regardless of the radiation characteristics of the antenna AN30.
【0306】
Further, in this embodiment, when a modulation method in which the symbols are independent in time is used, it is also possible to set whether or not to conceal the information by controlling the plane of polarization described above for each symbol. .. As a result, more stable communication can be performed by concealing a part of the symbol.
【0307】
(Embodiment 11) In FIG. 28, which is shown by assigning the same reference numerals to the portions corresponding to those in FIG. 19, 1100 indicates the wireless communication system according to the eleventh embodiment of the present invention as a whole. In the wireless communication system 1100, the antenna unit 1102 of the receiving station 1101 is composed of two linearly polarized antennas AN60 and AN61 whose polarization planes are orthogonal to each other, and the radiation characteristic control unit that controls the radiation characteristics of the antenna unit 1102 to the receiving station 1101. It has the same configuration as the wireless communication system of FIG. 19 except that 1104 is provided.
【0308】
Next, the operation of the wireless communication system 1100 will be described with reference to FIG. 24. Here, since the transmission / reception timing between the transmitting station 1001 and the receiving station 1101 is the same as that in the first embodiment, only the point of adjusting the polarization plane of the radio wave will be described.
【0309】
First, the receiving station 1101 transmits (transmits 1T) a polarization estimation signal (communication 1). At this time, the radiation characteristic control unit 1104 controls the radiation characteristics of the antenna unit 1102 via the transmission / reception unit 1103 so that the reference polarization plane is output from the antenna unit 1102. This transmission signal is received by the antenna unit 1003 of the transmission station 1001 in a state where the plane of polarization is rotated by reflection or diffraction on the propagation path 1011 and a delay is added.
【0310】
The transmitting station 1001 estimates the polarization plane referenced by the receiving station 1101 from the received (received 1B) signal of communication 1 in the propagation environment estimation unit 1006, and holds the estimation result. Next, the radiation characteristic control unit 1008 controls the polarization plane to be rotated by a preset angle with respect to the reference polarization plane estimated by the propagation environment estimation unit 1006, and transmits communication 2 (transmission 2B).
【0311】
The receiving station 1101 controls the radiation characteristic of the antenna unit 1102 by the radiation characteristic control unit 1104 so that the radiation characteristic control unit 1008 rotates the polarization plane by the above angle from the reference polarization plane to perform communication 2. Receive (receive 2T).
【0312】
That is, the radiation characteristic control unit 1008 of the transmission station 1001 and the radiation characteristic control unit 1104 of the reception station 1101 store in advance the rotation information of the plane of polarization shared only by each other's stations. Therefore, since the plane of polarization of communication 2 from the transmitting station 1001 and the plane of polarization of the radiation characteristics controlled by the receiving station 1101 are rotated by the same angle from the reference plane of polarization, the receiving station 1101 communicates with the optimum radiation characteristics 2 Can be received (received 2T). After that, the transmitting station 1001 and the receiving station 1101 communicate in the same manner.
【0313】
Thus, according to the above configuration, in addition to the configuration of the tenth embodiment, the receiving station 1101 is configured so that the radiation characteristics can be adaptively changed on the receiving station 1101 side, and the transmitting station 1001 and the receiving station 1101 are arranged. By sharing the rotation information of the planes of polarization and performing communication by matching the planes of polarization with each other, it is possible to realize a wireless communication system 1100 with higher security in addition to the effect obtained by the tenth embodiment.
【0314】
That is, even if a third party can know the plane of polarization in communication 1, it is difficult to know the plane of polarization in communication 2 because the plane of polarization is changed. Further, if the plane of polarization is rotated for each communication, the security can be further improved.
【0315】
Furthermore, independent information can be added to each of the two orthogonal planes of polarization, and each information can be separated based on the plane of polarization given in communication 1. In this way, the amount of transmission can be doubled, and extremely confidential communication that cannot be estimated by a third party can be realized.
【0316】
Generally, the transmitting station 1001 notifies the receiving station 1101 of the frequencies and times that can be used for communication, and the receiving station 1101 communicates using those resources. In general, the receiving station 1101 uses these resources to monitor the carrier status and starts communication at a time when the carrier is free. Two major factors were these conditions, frequency and time, but in this embodiment, the capacity of the communication itself can be increased up to twice by adding polarized waves to them.
【0317】
However, in this case, although the frequency and time have spatial identity, the polarization situation changes depending on the propagation path, so the environment differs depending on the location. Therefore, there is a problem that the positions of the polarization interference between the transmitting station 1001 and the receiving station 1101 are different. However, in an environment where the polarization states of the transmission station 1001 and the reception station 1101 in the propagation path 1011 are almost the same, for example, in an environment where the transmission station 1001 and the reception station 1101 can be seen or in an environment close to it. Can also be multiplexed by polarization as described above.
【0318】
In this way, when the two communications, the communication between the transmitting station 1001 and the receiving station 1101 and the communication between the transmitting station 1001 and another receiving station, are polarized and multiplexed at the same time and frequency, If the two communications are synchronized and the plane of polarization is switched at regular intervals, it becomes difficult to separate the two communications from a third party, so security can be improved.
【0319】
On the other hand, in an environment where visibility is not possible, the receiving station 1101 monitors the communication status emitted from other receiving stations in the vicinity in order to avoid interference with each other, notifies the monitoring information to the transmitting station 1001, and does not interfere with each other. If the transmission is performed when the conditions are met, the same communication as in the case of the line-of-sight condition becomes possible.
【0320】
Further, when considering a multipath environment, the planes of polarization from each path are different because the rotation directions and angles of the planes of polarization of each path are different. In this embodiment, the receiving station 1101 selectively receives a specific path according to the situation of the plane of polarization. As a result, the propagation path 1011 from the transmitting station 1001 to the receiving station 1101 is restricted, so that the effect of reducing the influence of multipath can be obtained.
【0321】
(Embodiment 12) As shown in FIG. 29, the wireless communication system 1200 of this embodiment has two transmission / reception units 1203 and 1204 in which transmission stations 1201 for transmitting confidential information are arranged at different positions. Further, only the receiving station 1202 performs the optimum transmission power and directional transmission from the two transmission / reception units 1203 and 1204 via different propagation paths 1207 and 1208, respectively.
【0322】
The received signal received by the transmission / reception units 1203 and 1204 is transmitted to the propagation environment estimation unit 1205. The propagation environment estimation unit 1205 estimates the environment of the two propagation paths 1207 and 1208 based on the two received signals. Specifically, the signal propagation time and the signal arrival direction in each propagation path 1207 and 1208 are estimated.
【0323】
The propagation environment adaptation unit 1206 controls the transmission operation when the transmission / reception units 1203 and 1204 transmit confidential information to the reception station 1202 based on the estimation result of the propagation environment estimation unit 1205. Specifically, first, the transmission timing of the transmission / reception units 1203 and 1204 is controlled so that the signals transmitted from the transmission / reception units 1203 and 1208 are received by the reception station 1202 at a preset reception time. Secondly, directional transmission is performed so that the directivity at the time of transmission at each transmission / reception unit 1203 and 1204 faces the receiving station 1202.
【0324】
FIG. 30, which is shown with the same reference numerals in the parts corresponding to those in FIG. 2, shows the detailed configuration of the transmission station 1201. As can be seen from FIG. 30, the two transmitter / receiver 1203 and 1204 shown in FIG. 29 are simply provided with two array antennas AN70 and AN71 at different positions, and the signal processing portions are the same. It has become. The arrival direction estimation unit 1210 and the delay amount estimation unit 120 in FIG. 30 correspond to the propagation environment estimation unit 1205 in FIG. 29, and the beam former 1222 and the timing control unit 118 in FIG. 30 correspond to the propagation environment adaptation unit 1206 in FIG. Equivalent to.
【0325】
Since the transmission timing of the confidential information by the transmission station 1201 has been described in detail in the above-described embodiment, the directional transmission of the confidential information will be mainly described in this embodiment.
【0326】
When the arrival direction estimation unit 1210 inputs two array antenna outputs via the radio reception unit (reception RF) 121, the arrival direction of the signal transmitted by the reception station 1202 is determined based on the amplitude and phase of the reception signals. presume. Specifically, the arrival direction is estimated by sequentially changing the weighting coefficient to be multiplied by the received signals of the two array antennas AN70 and AN71, and obtaining the weighting coefficient that maximizes the weighted addition value. Then, the estimation result estimated by the arrival direction estimation unit 1210 (that is, the weighting coefficient for each of the array antennas AN70 and AN71) is sent to the beam former 1222 of the transmission unit 1220.
【0327】
Here, the burst signal forming unit 1221, the beam former 1222, and the modulation unit 1223 of the transmitting unit 1220 are configured as shown in FIG. Incidentally, the transmission unit 1220 of this embodiment is designed to code-diffuse and multiplex the transmission data.
【0328】
The burst signal forming unit 1221 inputs an encryption key or encrypted user data to the data dividing circuit 1230. The data division circuit 1230 divides the input data into a plurality of data (two in the case of this embodiment) and sends the input data to the subsequent converter circuits 1231a and 1231b. In practice, the data division circuit 1230 divides the input data into a plurality of data D12a and D12b and sends the input data to the subsequent convolvator circuits 1231a and 1231b. Here, the diffusion code is shared between transmission and reception, but it is not necessary to share in advance which code the divided data D12a and D12b correspond to. However, the signal with large received power is defined as data D12a, and the others are defined as data D12b. Here, the confidential data such as the encryption key and the encrypted data is the data D12a, and the other information data is the data D12b.
【0329】
The combiner circuits 1231a and 1231b code-spread the input data by performing a convolution operation using the input data and the code generated by the code generation circuit 1232. Each code-diffused data is input to the gain control (GC) circuits 1234b and 1234c of the beamformer 1222. Further, the pseudo signal generated by the pseudo signal generation circuit 1233 is input to the gain control circuit 1234a.
【0330】
The gain control circuits 1234a to 1234c control the gain of each input data based on the estimated value from the arrival direction estimation unit 1210. The output of each gain control circuit 1234a to 1234c is input to the antenna matrix circuits 1235a to 1235c. The values estimated from the arrival direction estimation unit 1210 are also input to the antenna matrix circuits 1235a to 1235c.
【0331】
Each antenna matrix circuit 1235a to 1235c has the output of the corresponding gain control circuits 1234a to 1234c, the estimated value (optimal weighting coefficient) from the arrival direction estimation unit 1210, and the reception state (received power, delay distribution, etc.) at the receiving station 1202. Multiply the vector value based on. Specifically, based on the estimated propagation path environment, the receiving station 1202 performs signal power control that maximizes or minimizes the received power.
【0332】
In the antenna matrix circuit 1235b to which the confidential information is input, the data D12a is set to the maximum reception level at the receiving station 1202 based on the estimated value obtained by the arrival direction estimation unit 1210. Similarly, in the antenna matrix circuit 1235c to which the data D12b is input, the data D12b is set so that the reception level of the data D12b is sufficiently large and smaller than the data D12a at the receiving station 1202 based on the estimated value. The confidential information divided by this is received at the receiving station 1202 at different reception levels.
【0333】
On the other hand, in the antenna matrix circuit 1235a to which pseudo information is input, null (where the power becomes 0 due to wave interference) is set in the receiving station 1202 based on the estimation result obtained by the arrival direction estimation unit 1210. Control to form. As a result, the pseudo signal is not received by the receiving station 1202, and the pseudo signal is received by another receiving station at a position different from that of the receiving station 1202.
【0334】
Each transmission data vectorized by the antenna matrix circuits 1235a to 1235c is vector-added by the synthesis / frequency conversion circuit 1237 of the modulation unit 1223, and each element value obtained by this is frequency at the frequency obtained by the local oscillator 1236. Will be converted. The frequency-converted element signal is output from the corresponding element antennas of the array antennas AN70 and AN71.
【0335】
As described above, the transmitting station 1201 controls the reception state at the receiving station 1202 by allocating the data D12 to the main lobe of the radiation characteristics of the antenna, allocating the data D12b to the side lobe, and assigning the pseudo information to null. As a result, the receiving station 1202, which is the transmission target of the confidential information, can satisfactorily receive the divided confidential information data D12a and D12b with different powers, but the other receiving stations can receive the divided data D12a and D12b respectively. Confidential information cannot be received because the power difference between the two is reversed or the pseudo information interferes.
【0336】
FIG. 32 shows the configuration of the demodulation unit 1241 and the stream formation unit 1242 in the reception unit 1240 of the reception station 1202. Incidentally, the other configuration of the receiving station 1202 is the same as the configuration of the receiving station 102 shown in FIG. The demodulation unit 1241 inputs the output of the reception RF unit 140 (Fig. 3) to the converter circuit 1243. The same code as the diffusion code used in the transmission station 1201 is input to each converter circuit 1243 from the code generation circuit 1244.
【0337】
The convolver circuit 1243 performs a convolution operation at the timing specified by the timer 145. As a result, the data D12a and D12b corresponding to the spreading code are output from each convolvator circuit 1243 together with each reception level information. For example, one convolver circuit 1243 outputs confidential information, another convolvator circuit 1243 outputs significant information other than confidential information, and another convolvator circuit 1243 outputs pseudo information. Each data is selected / separated using these output data and reception level. By the way, it is difficult for other receiving stations to know the optimum timing for convolution calculation by the diffusion code, and even if they can be known, they are received at different reception levels, so each of these data is selected / separated. I don't get it.
【0338】
Each data output from the combiner circuit 1243 is sent to the data sorting / selection circuit 1247 of the stream forming circuit 1242 via the detector 1245, and is also sent to the amplitude detection circuit 1246. The amplitude detection circuit 1246 detects the amplitude of each data. Here, the transmitting station 1201 controls the transmission of the receiving station 1202 so that the data 12a is at the maximum level, the data D12b is at a smaller level, and the pseudo information is at the minimum receiving level. The reception level information corresponding to each data is output from the detection circuit 1246.
【0339】
The detection result obtained by the amplitude detection circuit 1246 is sent to the data sorting / selection circuit 1247. The data sorting / selection circuit 1247 sorts the data output from the detector 1245 according to the magnitude of the amplitude value based on the detection result obtained by the amplitude detection circuit 1246. Then, the data string is output with the maximum amplitude data as D12a and the second data as D12b.
【0340】
Next, the operation of the wireless communication system 1200 of this embodiment will be described with reference to FIG. 33.
【0341】
First, the receiving station 1202 outputs a predetermined propagation path estimation signal to the transmitting station 1201 by communication 1 (transmission 1T). The transmission station 1201 transmits the signal passing through the first propagation path 1207 to the first transmission / reception section 1203 (array antenna AN70 in FIG. 30) and the signal passing through the second propagation path 1208 to the second transmission / reception section 1204 (array in FIG. 30). Received by antenna AN71).
【0342】
At this time, the transmission station 1201 receives the propagation path estimation signal as a known signal by the first transmission / reception section 1203 and the second transmission / reception section 1204, so that the propagation path of the first propagation path 1207 and the second propagation path 1208 is received. Estimate the environment.
【0343】
The transmitting station 1201 controls the signals output from the first transmission / reception unit 1203 and the second transmission / reception unit 1204 by using the propagation path environment estimated from the signal output from the reception station 1202 in reverse. Specifically, the signal power of the confidential information at the receiving end of the receiving station 1202 is increased according to the estimated propagation path environment (arrival direction of the received wave) of the propagation environment adaptation unit 1206 of the transmitting station 1201. The first transmitter / receiver 1203 and the second transmitter / receiver 1204 are controlled to output a signal (communication 2) (transmission 2B). After that, communication 3 or later is performed in the same manner.
【0344】
In communication 2, confidential information is transmitted from the transmitting station 1201 to the receiving station 1202. The information of communication 2 is the result of combining the information from the first transmission / reception section 1203 of the transmission station 1201 via the first propagation path 1207 and the information from the second transmission / reception section 1204 via the second propagation path 1208 to the receiving station. Received at 1202 (received 2T). As described above, since the communication 2 is controlled so that the signal power at the receiving end of the receiving station 1202 is high, the receiving station 1202 can stably perform the receiving 2T and demodulate the confidential information.
【0345】
Moreover, since the signal (communication 2) output in this way is output at two places, the first transmission / reception unit 1203 and the second transmission / reception unit 1204, the signal as a result of spatial synthesis differs depending on the reception location. come. According to the above explanation, transmission control is performed so that the reception power at the reception end of the reception station 1202 is maximized, but since it is important to control so that the communication quality is high, the communication quality may deteriorate due to delay waves or the like. In some cases, it is also effective to reduce the received power to reduce the multipath component.
【0346】
On the other hand, when a third party who is not the destination intercepts the communication 2 including the confidential information and tries to extract the information, even if the information can be intercepted by the communication 1, the communication 2 is optimal at the receiving end of the receiving station 1202. Since the transmission is controlled so that the received signal is spatially synthesized, even if a third party receives this signal, the reception level is different and it is difficult to obtain the information.
【0347】
Further, in the case of this embodiment, in the communication 2, the pseudo information is code-division-multiplexed and transmitted in addition to the confidential information at the same time. Then, the receiving station 1202 restores each information data using the same spreading code as the transmitting station 1201. Here, when the code sequence is changed for each data as in the embodiment, the influence on the propagation path environment is also different because the frequency elements of the code sequence are different.
【0348】
As a result, by distributing the confidential information to the multiple channels as in this embodiment, the influence of the propagation status between the channels differs, so that it becomes more difficult for a third party to obtain the confidential information. ..
【0349】
In the explanation so far, attention has been paid to the point that the transmission signals of the first transmission / reception unit 1203 and the second transmission / reception unit 1204 are controlled so that the optimum reception signal reaches the reception end of the reception station 1202. In the following, two channels (confidential information and pseudo information) are superimposed on the same frequency at the same time, spatially synthesized using a transmission signal consisting of two or more, and the received power at the receiving end of the receiving station 1202 is calculated. The explanation will be given focusing on the point of controlling independently for the channel.
【0350】
The transmitting station 1201 estimates the first propagation path 1207 and the second propagation path 1208 based on the propagation path estimation signal which is a known signal received (reception 1B) from the receiving station 1202. Next, the transmitting station 1201 transmits two types of information to the receiving station 1202 by code-division multiple access for two channels.
【0351】
Here, the channels assigned to each are selected so that the diffusion gains are equal and have an orthogonal relationship. At this time, as the first information, the confidential information is transmitted at the receiving end of the receiving station 1202 so as to have the optimum receiving condition based on the estimated propagation path condition. Here, control is performed so that the received power is maximized as the optimum reception situation. As the second information, the pseudo information is controlled and transmitted at the receiving end of the receiving station 1202 based on the estimated propagation path condition so that the received power is smaller than the first information.
【0352】
The communication 2 radiated in this way is spatially synthesized and received by the receiving station 1202. As a result of spatial synthesis, at the receiving end, the first information is received as a high power signal and the second information is received as a low power signal in a code division multiple access state. The received signal series can extract each other's signals by despreading using the spreading code, but since the spreading gains are set to be equal, one has a large power according to the received power of each information. The other has less power. The receiving station 1202 can easily select the secret information by selecting the information of the channel having a large received power as the secret information and treating the information of the other channel as the pseudo information.
【0353】
On the other hand, even if a third party intercepts and restores this information, the reception status of the first information and the reception status of the second information differ depending on the receiving location. It is impossible to know from the series. Therefore, communication 2 cannot be known by a third party.
【0354】
By performing frequency diffusion in this way, it is possible to obtain an effect that the communication quality can be improved because the resistance to noise is increased.
【0355】
Incidentally, the case of controlling the combined and received power through the propagation paths 1207 and 1208 for the channels on which the pseudo information is superimposed has been described, but the received power of the channels on which the pseudo information is superimposed is set to 0, that is, each other. When controlling to cancel, there is a feature that the spatial area to be canceled is an extremely narrow area.
【0356】
Figure 34 shows how electromagnetic waves are spatially synthesized here. FIG. 34 shows the state of a standing wave with two waves. The horizontal axis shows the position and the vertical axis shows the electric power. As can be seen from this figure, when the maximum level is normalized to 0 dB, most positions are above -10 dB. In addition, due to spatial composition such that the value is -20 dB or less, radio waves are canceled each other and the low power part has a sharp peak, and the power rises sharply even if the position is slightly deviated.
【0357】
Using this characteristic, for example, if the signal power of the first information is set to about -10 dBm and the transmission control is performed so that the second information is canceled at the receiving end, the area where the interference of the second information can be ignored is limited. It can be seen that the first information cannot be received correctly in most areas. That is, the first information is disturbed by the second information in a place other than the place where the receiving station 1202, which is the communication target, is located. This makes it very difficult for a third party to obtain the first information.
【0358】
Thus, according to the above configuration, in addition to transmitting the confidential information at the timing of being received by the receiving station 1202 at the time set via the plurality of propagation paths 1207 and 1208, it is the destination of the confidential information. By controlling the directionality of the transmitting station 1201 so that the receiving power of the confidential information is maximized at the receiving station 1202, it becomes more difficult for a third party to obtain the confidential information, and the communication quality at the receiving station 1202. It is possible to realize a wireless communication system 1200 that can obtain good confidential information.
【0359】
Moreover, this embodiment has a high affinity with the array antenna technology. This technique has a great feature that the radiation characteristics can be electrically controlled, and this embodiment is actively applied.
【0360】
Therefore, the features of the array antenna itself can be utilized as they are. For example, when the communication 2 described in the explanation is performed, the communication of another channel is directed in a direction unrelated to the communication with the receiving station 1202. Or the radiation characteristics can be controlled in communication in a multipath environment. By doing these, the communication capacity can be increased, or the influence of multipath can be reduced.
【0361】
(Other embodiments) (1) In the above-described embodiment, the case where the reference time of the receiving terminal reference time is set as the network reference time for the transmitting station to transmit to the receiving station by communication 1 has been described, but the present invention is limited to this. In short, it is sufficient that the transmitting station and the receiving station have the same time. For example, a preset time can be used as a reference. Further, if the reference time notification signal is transmitted from the receiving station to the transmitting station, the transmitting station whose transmission line delay can be estimated can adjust the reference time to the receiving station from the reception time of the reference time notification signal.
【0362】
(2) Further, in the above-described fourth embodiment, the case where the transmission station performs transmission at the transmission timing such that the transmission data including the confidential information arrives at the reception terminal reference time set by the reception station has been described. Is not limited to this, and may transmit the transmission data including the confidential information at the transmission timing shifted by a predetermined time with respect to the reception terminal reference time set by the transmission station. In this case, as described above in the fourth embodiment, the receiving station performs the receiving process using the synchronous sequence signal that can be extracted only by the receiving station that is the transmission target of the confidential information.
【0363】
Specifically, it will be described with reference to FIG. First, the transmitting station transmits a control signal including the network reference time to the receiving station (communication 1). Next, the receiving station transmits a response signal to the transmitting station after a certain period of time (T1) (communication 2), and sets the receiving end reference time (Tk). Next, the transmitting station estimates the state of the propagation path from communication 1 and communication 2. Specifically, the signal propagation time (Td) is estimated.
【0364】
Next, the transmitting station performs communication 3 with the receiving station. At this time, the transmitting station calculates the transmission time from the estimated signal propagation time (Td) and the processing delay time generated by the device, and controls the transmission timing. The transmitting station controls the time so that the communication 3 reaches the receiving end reference time (Tk) at the receiving station, and at this time, the delay amount (Ts) determined according to the additional information is added to the receiving end reference time (Tk). Send communication 3. As a result, the receiving station receives the communication 3 at the time (Tk + Ts). The receiving station performs time synchronization by performing reception processing for communication 3 over several symbols centered on the time (Tk). The time synchronization can be performed here because the synchronization sequence signal is arranged in the transmission signal in a format known only between the transmitting station and the receiving station. That is, in the receiving station having the above-described configuration in the fourth embodiment, even if the transmission data does not arrive exactly at the reception end reference time (Tk), the reception processing can be performed using the synchronous series signal.
【0365】
Then, the result of time synchronization and the time (Tk) difference (Ts) are separately passed to the processing system as additional information. At this time, the following applications can be considered using additional information.
【0366】
First, multiple scramble formats are defined between the transmitting and receiving stations, and these are switched according to additional information. The second is to divide the confidential information into multiple pieces and convey the type by additional information. That is, the transmitting station divides the confidential information into the first and second information and transmits it, and the receiving station demodulates the first divided confidential information when the additional information (Ts) is positive, and when it is negative, it demodulates the first divided confidential information. Demodulates the second partition secret information. Thirdly, multiple encryption patterns are prepared and switched according to additional information (Ts).
【0367】
As a result, it becomes more difficult for other receiving stations to recover the confidential information. In addition, the transmitting station and the receiving station that transmit and receive the confidential information can restore the confidential information even if the reception end reference time (Tk) is not exactly the same, which increases the degree of freedom in design.
【0368】
(3) Further, in the above-described embodiment, when the transmission timing by the transmitting station is controlled so that the signal transmitted from the transmitting station arrives at the receiving terminal reference time set by the receiving station for all the information. However, the present invention is not limited to this, and such transmission / reception is performed only for transmission of particularly important confidential information such as an encryption key, and synchronization such as a pilot signal is performed for other information. A signal may be added and transmission may be performed at a normal timing. By doing so, the instability at the time of demodulation caused by not adding the synchronization signal and not performing the synchronous demodulation processing can be suppressed to the minimum, and the communication quality as a whole can be improved.
【0369】
(4) Further, in the above-described embodiment, the case where the synchronization series and the pseudo-synchronization series are composed of a plurality of symbols has been described, but the present invention is not limited to this, and each may be composed of one symbol. Further, the pseudo-synchronous series may also be used as a pseudo symbol, an information symbol, or a part of the synchronous series.
【0370】
Further, as the synchronization series, the repetition of a monotonous pattern such as a sine wave may be used. In this case, the receiving terminal 1 to which the confidential information is transmitted can estimate the start time of the synchronization series, whereas the receiving terminal 2 cannot estimate which pattern is the start time of the synchronization series. Therefore, even if a part of the synchronization series is a pseudo-synchronization series, the reference phase obtained from the synchronization series changes (rotates) depending on the timing, so that the same effect as that of the above-described embodiment can be obtained.
【0371】
Further, it is not necessary to limit the synchronization series to one type, and a plurality of types of synchronization series may be used. In this way, it becomes more difficult for a third party to demodulate and decrypt the confidential information. Furthermore, if the format showing the arrangement of information symbols and pseudo symbols is changed according to the type of synchronization series, higher security can be ensured.
【0372】
(5) Further, in the above-described embodiment, the case where the pseudo information is placed on the pseudo symbol has been described, but the present invention is not limited to this, and the pseudo symbol is provided with an error detection function and an error correction function for the first normal information. It may be posted as the second regular information. It can also be replaced with an information sequence represented by a convolution code sequence or a block code sequence, and a pseudo information sequence thereof.
【0373】
(6) Further, in the above-described embodiment, the case where communication is performed via the two propagation paths of the first propagation path and the second propagation path by providing two transmission units in the transmission station has been described. The invention is not limited to this, and three or more propagation paths for communication may be provided by providing three or more transmission units.
【0374】
Further, in the above-described embodiment, the case where two propagation path communication is realized by providing two transmission units in the transmitting station has been described, but the method for realizing a plurality of propagation path communication is not limited to this, and for example, each Different propagation path communications can also be realized by arranging the transmitters at different positions. Further, the transmitting units may be installed at the same position, and an antenna having narrowed directivity of each transmitting unit may be applied. Further, the number of transmitters may be one, and an adaptive array antenna may be applied to the transmitter to form different communication propagation paths by utilizing characteristics such as reflection and diffraction of radio waves. In short, it is sufficient to form a plurality of propagation paths that can be shared only between wireless communication stations that communicate confidential information with each other.
【0375】
(7) Further, in the above-described embodiment, in order to simplify the explanation, the power of the pseudo symbol is assumed to be 0, but the power of the pseudo symbol does not have to be 0. In order to reduce the interference with the significant symbol, the pseudo symbol power should be sufficiently small. Further, the pseudo symbol may be divided into a plurality of parts so that the power as a result of vector synthesis becomes sufficiently small.
【0376】
(8) In the above-described embodiment, as an estimation of the polarization state, an example of obtaining the angle consisting of the long axis of the elliptically polarized wave p and the antenna and the flatness is given, but the configurations shown in FIGS. 21 and 22 are shown. Of these, by using only the electric field strength detection unit 1020 and the electric field strength control unit 1021, the polarization plane may be controlled by obtaining only the approximate major axis angle. You may change to a simple configuration.
【0377】
Further, in the above-described embodiment, the case where linearly polarized waves are used has been described, but the present invention is not limited to this, and the same effect can be obtained for circularly polarized waves. In this case, vertically polarized waves and horizontally polarized waves are replaced with right-handed polarized waves and left-handed polarized waves.
【0378】
(9) Further, in the above-described embodiments 10 and 11, the case where communication is performed between the transmitting station and the receiving station using one propagation path has been described, but the present invention is not limited to this, and the present invention is not limited to this, and a plurality of propagation paths are also used. It is clear that similar communications can be achieved.
【0379】
In this case, the time diversity effect can be obtained by shifting the time between the communication using the first propagation path and the communication using the second propagation path. On the contrary, if both communications are performed at the same time, the path diversity effect can be obtained. Naturally, it is more difficult for a third party to estimate two or more propagation paths than to estimate one propagation path, so if information is distributed to multiple propagation paths, the security of confidential information will be dramatically improved. Can be raised.
【0380】
(10) Further, in the above-described embodiment 10, a dipole antenna is used as an example of the antenna, but the type of antenna is not limited, and a helical antenna, a planar antenna, a parabolic antenna, a Yagi antenna, and all other antennas are used. The same effect can be obtained even if there is. Furthermore, if pseudo-information is radiated in a direction unrelated to communication by using adaptive array antenna technology that electrically controls directivity using multiple antennas, it will be more difficult for a third party to intercept confidential information. can do. In addition, the angle of the plane of polarization can be changed along with the radiation characteristics. Further, if an antenna such as an array antenna whose directivity can be electrically controlled is used, it can be easily applied to a communication method using a plurality of propagation paths.
【0381】
(11) Further, in the above-described embodiment, the security of the confidential information has been focused on, but in addition to the above-mentioned estimation of the propagation environment performed during the communication of the confidential information, the estimation of the propagation environment is also performed in the subsequent communication, and both are performed. By comparing the estimation results of, it is possible to authenticate whether or not the receiving station is the communication partner of the confidential information at the transmitting station.
【0382】
(12) Further, in the above-described embodiments 10 and 11, the case where the polarization estimation signal is output for the propagation environment estimation has been described, but the polarization estimation signal may be a sine wave and has one or more symbols. It may be a configured signal sequence.
【0383】
Further, in the above-described embodiments 10 and 11, the case where the rotation angle and the amplitude of the polarization plane in the propagation path are detected by making the polarization estimation signal linearly polarized has been described. For example, if the polarization estimation signal is transmitted at different times so that the signal on the polarization plane orthogonal to it can be separated, or if the polarization estimation signals that are orthogonal to each other are assigned and multiplex transmission is performed, the polarization estimation signal is transmitted. It is possible to detect the rotation of polarization and the phase difference between the transmitting side and the receiving side.
【0384】
(13) Further, in the above-described 12th embodiment, a case where pseudo information is code-division-multiplexed and transmitted to a receiving station in addition to confidential information by using a diffusion code has been described, but the present invention is not limited to this. For example, each data may be frequency-division-multiplexed or orthogonal frequency-division-multiplexed and transmitted.
【0385】
(14) Further, in the above-described 12th embodiment, the case where the diffusion gains of the code sequences used for the first information (confidential information) and the second information (pseudo-information) are made equal has been described, but it is not always necessary to make them equal. Also, orthogonality is not always necessary, and if the reception end of the receiving station is controlled so that there is a sufficient difference in received power, even if the exact same code sequence is given to the first information and the second information and diffused. , Or even a configuration in which the code length is 1 (that is, no diffusion) can be realized. In this case, in the received signal intercepted by the third party, the signal of the second information on which the pseudo information is superimposed becomes an interfering wave, so that the third party cannot obtain the first information.
【0386】
Further, here, it has been described that the present invention can be carried out even if the same code is assigned to the first information and the second information, but the reception power when the second information is spatially combined at the receiving end is controlled to be sufficiently small. Then, the received signal becomes almost only the first information, and it is not necessary to separate the multiplexed signals. That is, the same effect can be obtained without performing code diffusion at multiple stages.
【0387】
Therefore, the first information and the second information are superimposed only by controlling the received power at the receiving end of the receiving station to be large and the power of the other sufficiently small based on the estimated propagation path condition. All you have to do is let it. In this way, the confidential information can be transmitted by communication 2 without degrading the transmission efficiency. In this case, if the total power of the small signal has a power difference of about 1 dB or more with respect to the power of the large signal, these can be separated on the receiving side.
【0388】
(15) Further, in the above description, the code division multiple access (CDMA) method in which the spreading code is assigned to each carrier has been described as the multiplexing method, but the same effect can be obtained by using OFDM multiplexing. That is, in the case of CDMA, the combined power for each spreading code is controlled, but when OFDM is applied, the combined power for each subcarrier may be controlled. For example, the subcarriers may be divided into a plurality of groups (for example, odd-numbered subcarriers and even-numbered subcarriers), and the combined power of each subcarrier group may be controlled.
【0389】
(16) Further, in the twelfth embodiment, the case where the multiplexed second information is used as pseudo information has been described, but the second information is not limited to the pseudo information, and may be, for example, information of another channel. In this way, the transmission efficiency can be improved. It is also possible to transmit both the first information and the second information as confidential information, and the receiving station separates the first information and the second information according to the magnitude of the received power and decodes them.
【0390】
Further, in addition to the first information and the second information transmitted from the transmitting station, information such as the power value of both, the order of their magnitudes, or the power ratio of both may be superimposed and transmitted. Further, the number of multiplex data to be transmitted in communication 2 is not limited to two or three, and four or more pieces of information may be multiplexed and transmitted. In this case, the receiving station can separate those signals into the first to nth (n is a natural number of 2 or more) information according to the magnitude of the received power and decode it. In this way, even if a third party tries to intercept the information, the propagation path is different, so that the correct order of the received power magnitudes cannot be obtained, and the confidentiality of the information is increased.
【0391】
(17) Further, in the above-described 12th embodiment, the case where the transmitting station has two transmitting / receiving units has been described, but the number of transmitting / receiving units is not limited to two. It is also known that when controlling the radiation characteristics using an array antenna, if the antenna element is N, only N-1 null characteristics can be created so that the signal is canceled by spatial synthesis and the signal power becomes 0. .. A method using this feature will be described with reference to FIG. 35.
【0392】
As shown in FIG. 35 in which the corresponding parts corresponding to those in FIG. 29 are designated by the same reference numerals, in the wireless communication system 1300, the third transmission / reception unit 1302 is added to the transmission station 1301, and the third propagation path 1307 is newly formed as the propagation path. Will be done.
【0393】
Similar to the above-described 12th embodiment, the transmitting station 1301 receives the propagation path estimation signal as a known signal from the receiving station 1202, and the propagation environment estimation unit 1303 causes the first propagation path 1305 and the second propagation path 1306. , Estimate the propagation environment of the third propagation path 1307.
【0394】
Next, the transmitting station 1301 transmits the three types of information to the receiving station 1202 by code-division multiple access for three channels. Select channels to be assigned to each so that the diffusion gains are equal and orthogonal to each other.
【0395】
At this time, the secret information is used as the first information, and the receiver + signal end of the receiving station 1202 is based on the estimation results of the first propagation path 1305, the second propagation path 1306, and the third propagation path 1307 in the estimated propagation path environment. Send so that the reception status is optimal. Here, control is performed so that the received power is maximized as the optimum reception situation. Pseudo-information is used as the second information, and the received power is the minimum at the receiving end of the receiving station 1202 based on the estimation results of the first propagation path 1305, the second propagation path 1306, and the third propagation path 1307 in the estimated propagation path environment. Null control is performed so that
【0396】
At this time, one of the two controllable null characteristics is used, and the other null characteristic is set so that the communication can be maintained in an appropriate state. Furthermore, pseudo information is used as the third information, and the received power is the minimum at the receiving end of the receiving station 1202 based on the estimation results of the first propagation path 1305, the second propagation path 1306, and the third propagation path 1307 in the estimated propagation environment. Null control is performed so that At this time, of the two null characteristics, one null characteristic has the same characteristics as the second information, but the other null characteristic is null-controlled and transmitted so as to be in a different state from the second information.
【0397】
The three information signals radiated in this way are spatially synthesized and received by the receiving station 1202. As a result of spatial synthesis, at the receiving end, the first information is received as a high power signal, and the second and third information are received as code division multiple access as a low power signal.
【0398】
The received signal sequences can be decentralized using a spreading code to extract each other's signals. Since the diffusion gain is set to be equal here, one has a large power and the other has a small power according to the received power of each information. The receiving station 1202 can easily extract only the secret information by selecting the information of the channel having a large power as the secret information and treating the information of the other channel as the pseudo information.
【0399】
Here, consider a case where a third party intercepts and restores confidential information. In this case, the reception state of the first information and the reception state of the second and third information differ depending on the receiving place. This reception state cannot be known in advance, nor can it be known from the received signal sequence.
【0400】
Further, the radiation characteristics of the multiplexed third information are controlled so that nulls are formed at the receiving end of the receiving station 1202, as in the second information, but the null states are controlled so as to be different from each other. Even when the null is controlled here, the null may be formed in addition to the control location depending on the conditions. For example, even if the second information is near the null at the reception position of a third party, the third information Is rarely in the same state. As a result, the probability that the contents of confidential information will be leaked to a third party is greatly reduced. Thus, in a configuration in which three transmission / reception units are provided, confidentiality can be significantly improved as compared with the case where two transmission / reception units are used.
【0401】
Similarly, by increasing the number of transmission / reception units of the transmitting station to 4, 5, and 6, the number of multiplex can be increased to further improve the confidentiality. Further, if the number of multiplex is suppressed with respect to the number of transmitters and receivers and the degree of freedom of null control for each piece of information to be multiplexed is improved, the accuracy can be improved and the control can be enhanced. Further, if the parameter setting used for null control is changed for each symbol so that the null parts formed outside the control do not overlap, the possibility of leakage of confidential information to a third party can be further suppressed.
【0402】
Further, the case where the receiving station controls the reception power of the second information and the third information to be reduced by null-controlling the second information and the third information has been described, but the reception of the second information and the third information has been described. If the power is controlled so as to be different from the first information and the magnitude information of each received power is added to the first to third information, higher confidentiality can be obtained. Furthermore, if the control is changed every moment for each symbol, leakage can be further prevented.
【0403】
(18) Further, in the above description, the case where the transmission power of the first information, which is confidential information, and the transmission power of other information multiplexed therein are equal is described. However, these do not necessarily have to be equal, and for example, if the transmission power of the first information is set lower than that of other information, the confidentiality can be improved. On the contrary, if the transmission power of the first information is set higher than that of the other information, the communication of the confidential information can be stabilized. These may be appropriately adjusted according to the environment of the provided wireless communication system and the like.
【0404】
(19) In the above-described embodiment, the propagation path estimation signal is a known signal for the sake of explanation, but the propagation path can be estimated even if the signal is not a known signal. However, if it is a known signal, it is easy to estimate, and there is an advantage that the influence of noise can be reduced. The envelope der constant signal can be Re CMA method is estimation algorithm of the adaptive array antenna applied. Furthermore, the propagation path estimation signal is necessary when the propagation environment changes, and if the propagation path formed between the transmitting station and the receiving station is fixed, secret communication is performed by measuring the characteristics in advance. It can be performed.
【0405】
(20) Further, as an antenna when a plurality of transmitter / receivers are provided, an array antenna has been described as an example, but the configuration of the array antenna is not limited. If the coherency of the modulated wave can be controlled, the same control can be performed using two or more transmitting stations. In addition, if an antenna that can electrically control the radiation characteristics, such as an array antenna, is used, the transmitting station can communicate with another radio station independently of the communication with the receiving station that is transmitting confidential information. it can. In this case, as described above, the communication signals can be multiplexed and transmitted to each receiving station at the same time and at the same frequency. By increasing the number of multiples in this way, the effect of preventing leakage of confidential information to a third party is further enhanced. When there is no separate receiving station and communication is performed only by a pair of transmitting stations and receiving stations, the security of the confidential information can be maintained by multiplexing the pseudo information as described above.
【0406】
(21) Further, in the above-described embodiment, code division multiple access has been described as an example as a multiplexing method for multiplexing a plurality of types of information on confidential information, but each information can be selected by using the radiation characteristic control of the array antenna. Therefore, it is not particularly limited to the multiplex method.
【0407】
(22) Further, the present invention can be used without limiting the modulation method and the multiplexing method. For example, each of the above-mentioned communication 1, communication 2, communication 3, communication 4, ..., and the above-mentioned communication 10 and communication 11 in the fifth, sixth, and seventh embodiments of the first to fourth embodiments. , Communication 20, communication 21, communication 30, communication 31, communication 4, ... It is also possible to apply a different modulation method or multiplex method for each. In particular, when estimating the propagation environment, by applying spectral diffusion to communication 1 as in the first embodiment, fading resistance can be achieved and estimation processing with good estimation accuracy can be performed.
【0408】
Further, an ASK modulation method, an FSK modulation method, a difference code modulation method or an OFDM (Orthogonal Frequency Division Multiplexing) method may be applied. When these modulation methods are used, there is an advantage that it is not necessary to perform phase synchronization in particular.
【0409】
In addition, PSK modulation, QAM modulation, pulse modulation and the like can also be applied. Further, since it does not depend on the multiplexing method, FDMA multiplex wave, CDMA multiplex wave, OFDM multiplex wave and the like can also be applied.
【0410】
That is, in the above-described embodiment, the case of controlling the transmission of confidential information in units of time or channel has been described, but if a multicarrier modulation method such as CDMA multiplex wave or OFDM multiplex wave is used, the plane of polarization is used for each carrier. Can be controlled. Therefore, more advanced control can be performed by performing control by carrier in addition to control by time and channel. As a result, the confidentiality to a third party can be dramatically improved.
【0411】
Further, if the symbol rate in the communication 3 of the first embodiment is set lower than the symbol rate of the communication 1 and the communication 2, the accuracy of the propagation path delay can be relatively improved. At this time, the accuracy of the positional relationship between the transmitting station and the receiving station is determined by the symbol rate of communication 3 and the processing time from communication 1 to communication 3, so if individual values are set according to the system design, Good.
【0412】
Similarly, the positional relationship between the transmitting station and the receiving station depends on the symbol rates of the communication 30 and the communication 31 in the fifth, sixth, and seventh embodiments and the processing time from the communication 10 to the communication 30 or the communication 11 to the communication 31. Since the accuracy of is determined, individual values may be set according to the system design.
【0413】
As described above, the present invention is not limited to the modulation method and the multiplexing method, and does not affect other information layers, and therefore has a high affinity with the conventional system. In addition, since higher security can be realized by combining with encryption technology, it can be widely applied to the information and communication field where high security is required such as personal information, financial information, and confidential information.
【0414】
(23) Further, in the above-described embodiment, the signal propagation time in the propagation path is estimated, and the transmission / reception synchronization between transmission / reception is performed using this signal propagation time so that other users cannot restore the confidential information. Although the above-mentioned case has been described, the same effect as that of the above-described embodiment can be obtained by using another propagation path environment that can be shared only by the radio stations communicating with each other. This propagation environment includes, for example, a multipath environment and a fading environment, and these may be used in combination. Further, even higher security can be realized by applying it to communication including the device difference between the transmitting station and the receiving station (for example, the difference in the reference frequency).
【0415】
(24) Further, in the above-described embodiment, in order to simplify the explanation, a radio station that transmits information including confidential information is used as a transmitting station, and a radio station that receives the information is used as a receiving station. Not limited to this, confidential information may be transmitted and received to and from each other.
【0416】
(25) Further, in the above-described embodiment, the transmitting station and the receiving station share the same reference period by transmitting a control signal including a network reference time as a signal for synchronizing with the receiving station. However, the case where the network time Tk is set as the arrival time of the confidential information has been described, but the present invention is not limited to this, and is set by the receiving station as in the above-described embodiment without sharing the same reference time. Confidential information can be reached at that point.
【0417】
This will be described with reference to FIG. The transmitting station transmits communication 1 at time t1. It is assumed that this communication 1 does not include the reference time information unlike the embodiment. The receiving station receives communication 1 at time t2. Then, when the time T1 elapses, the receiving station transmits the communication 2 at t3. The transmitting station receives communication 2 at time point t4. In addition, the receiving station transmits communication 2'at time t5 after a certain period of time (this time does not need to be shared between transmission and reception). The transmitting station receives communication 2'at time t6. The transmitting station transmits communication 3 at the time point t7 after the time Td has elapsed from the time point t6. Here, the transmitting station and the receiving station hold the time T1 from the reception 1T to the transmission 2T and the time T2 from the transmission 2'T to the reception 3T as shared information.
【0418】
Here, assuming that the signal propagation time is Tw, the relationship of the following equation holds. t4-t1 = 2 × Tw + T1 ......... (1) Therefore, the signal propagation time Tw is calculated by the following equation. Tw = (t4-t1-T1) / 2 ......... (2) It can be expressed as. The time point t7 that the transmitting station should transmit so as to reach the receiving end reference time 1 (time point t8) is due to the relationship with the time points t5, t6, and T2. t7 = t8-Tw = (t5 + T2)-Tw = t6 + T2-2 × Tw ......... (3) That is, the adjustment time Td (= t7-t6) is given by the following equation. Td = T2-2 × Tw = T2- (t4-t1-T1) ......... (4) It can be expressed as.
【0419】
In this way, the adjustment time Td for the transmission timing of the transmitting station can be expressed by the time points t1 and t4 known to the transmitting station and the shared time information T1 and T2, so that the transmitting station has a time point based on Eq. (4). Transmission data including confidential information can be transmitted at a transmission timing such that the confidential information reaches the receiving station at t8.
【0420】
[Effect of the invention]
As described above, according to the present invention, when the transmission data including the confidential information is wirelessly transmitted from the first wireless station to the second wireless station, the first wireless station is transmitted before the confidential information is transmitted. By transmitting and receiving signals between the first radio station and the second radio station, the radio propagation path environment shared only between the first radio station and the second radio station is estimated, and the estimated radio propagation path environment is taken into consideration. By transmitting the confidential information from the first wireless station to the second wireless station, the confidential information can be transmitted with high security when transmitting the confidential information to a specific wireless station via the wireless line. A data transmission device, a wireless communication system, and a wireless communication method that can be transmitted can be realized.
[Simple explanation of drawings]
[Figure 1]
Block diagram showing the configuration of the wireless communication system according to the first embodiment of the present invention. [Figure 2]
Block diagram showing the configuration of the transmitting station of FIG. [Fig. 3]
Block diagram showing the configuration of the receiving station in FIG. [Fig. 4]
A sequence diagram showing a communication procedure in the wireless communication systems of the first and third embodiments. [Fig. 5]
The figure which shows the propagation state of the communication signal of Embodiments 1 and 3. [Fig. 6]
The block diagram which shows the structure of the burst signal forming part of Embodiment 4. [Fig. 7]
A block diagram showing a configuration of a demodulation unit and a stream forming unit according to the fourth embodiment. [Fig. 8]
Block diagram showing the configuration of the time synchronization / unique word extraction circuit of the fourth embodiment [Fig. 9]
Signal waveform diagram used to explain the operation of the time synchronization / unique word extraction circuit of FIG. [Fig. 10]
The figure which shows the propagation state of the communication signal of Embodiment 4. [Fig. 11]
Block diagram showing the configuration of the wireless communication system of the fifth embodiment [Fig. 12]
A sequence diagram showing a communication procedure in the wireless communication systems of the fifth, sixth, and seventh embodiments. [Fig. 13]
The figure which shows the propagation state of the communication signal of Embodiment 5. [Fig. 14]
The figure which shows the propagation state of the communication signal of Embodiments 6, 7 and 9. [Fig. 15]
Block diagram showing the configuration of the wireless communication system of the eighth embodiment [Fig. 16]
Sequence diagram showing communication procedure in wireless communication system of Embodiments 8 and 9. [Fig. 17]
Block diagram showing the configuration of the wireless communication system of the ninth embodiment [Fig. 18]
Block diagram showing the configuration of the transmitting station of FIG. [Fig. 19]
Block diagram showing the configuration of the wireless communication system of the tenth embodiment [Fig. 20]
Block diagram showing the configuration of the transmitting station of FIG. [Fig. 21]
Block diagram showing the configuration of the propagation environment estimation unit in Fig. 20 [Fig. 22]
Block diagram showing the configuration of the radiation characteristic control unit of FIG. 20 [Fig. 23]
Diagram used to explain the plane of polarization, electric field strength, and phase difference [Fig. 24]
Sequence diagram showing communication procedure in wireless communication system of Embodiments 10 and 11. [Fig. 25]
The figure which provides the explanation of the operation of Embodiment 10. [Fig. 26]
Diagram for explaining the position of the antenna and the plane of polarization [Fig. 27]
Diagram for explaining the position of the antenna and the plane of polarization [Fig. 28]
Block diagram showing the configuration of the wireless communication system of the eleventh embodiment [Fig. 29]
Block diagram showing the configuration of the wireless communication system of the twelfth embodiment [Fig. 30]
Block diagram showing the configuration of the transmitting station of FIG. 29 [Fig. 31]
Block diagram showing the configuration of the burst signal forming unit, beam former, and modulation unit of FIG. 30 [Fig. 32]
A block diagram showing the configuration of the demodulation section and the stream forming section of FIG. [Fig. 33]
A sequence diagram showing a communication procedure in the wireless communication system of the twelfth embodiment. [Fig. 34]
Diagram used to explain the spatial synthesis of electromagnetic waves [Fig. 35]
A block diagram showing a configuration of a wireless communication system according to another embodiment. [Fig. 36]
A sequence diagram showing a communication procedure according to another embodiment [Explanation of symbols]
100, 500, 800, 900, 1000, 1100, 1200, 1300 wireless communication system 101, 501, 801, 802, 901, 1001, 1201, 1301 transmitters 101a, 102a, 502, 503, 1012, 1220 Transmitter 101b, 102b, 1013, 1240 receiver 101c, 904, 1006, 1205, 1303 Propagation environment estimation unit 101d, 905, 1206, 1304 Propagation Environment Adaptation Department 102, 1002, 1040, 1101, 1202 receiving stations 102c, 1007, 1010 time control unit 103, 504, 505, 806, 807, 906, 907, 1041, 1042, 1207, 1208, 1305, 1306, 1307 Propagation path 115, 132, 300, 1221 Burst signal former 116, 134, 1223 Modulator 118, 905a Timing control section 120, 904a Delay amount estimation unit 122, 141, 310 Demodulator 123, 142, 320 Stream forming part 330 Convolver circuit 312 Time synchronization / unique word extraction circuit 333 Peak search circuit 334 Search range setting circuit 335 Unique word selection circuit 803, 804 Network connection 805 network 902, 903, 1005, 1009, 1203, 1204, 1302 Transmitter / receiver 904b Power measurement unit 905b Power control unit 1003, 1004, 1102, 1103 Antenna part 1008, 1104 Radiation characteristic control unit 1210 Arrival direction estimation unit 1222 beam former AN, AN11, AN12, AN13, AN20, AN21, AN30, AN60, AN61 antennas D1, D2, D3 user data D4 scrambled puncture data
11 sheets
Sheet 1 Sheet 2 Sheet 3 Sheet 4 Sheet 5 Sheet 6 Sheet 7 Sheet 8 Sheet 9 Sheet 10 Sheet 11
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| Document | Office | Kind | Date |
|---|---|---|---|
| 2000260413(P2000260413) | Japan | – | |
| 2000260413 | Japan | A |
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| Document | Office | Kind | |
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| WO0219569A1 | World Intellectual Property Organization (WIPO) | A1 | |
| WO0219569A9 | World Intellectual Property Organization (WIPO) | A9 | |
| JP2002152191AThis record | Japan | A | |
| EP1233547A1 | European Patent Office (EPO) | A1 | |
| US2002181439A1 | United States of America | A1 | |
| CN1394399A | China | A | |
| CN1276595C | China | C | |
| EP1233547A4 | European Patent Office (EPO) | A4 | |
| CN1913395A | China | A | |
| JP4794085B2 | Japan | B2 |
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Numbers
- Publication
- 2002-152191
- Application
- 258837
Titles2
- Japanese
- 【発明の名称】データ伝送装置、無線通信システム及び無線通信方法
- English
- Description: Data transmission device, wireless communication system, and wireless communication method.
Classification
- IPC, 3
- H04L9 12
- H04B7 26
- H04L7 00