Communication apparatus and communication method
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10 claims: 7 independent, 3 dependent
- 1所定の変調方式の第1のマッピング方法とは異なる少なくとも1つ以上のマッピングパターンを有する第2のマッピング方法及び前記第1のマッピング方法からマッピングパターンを決定し、前記決定されたマッピングパターンの情報を含むフレーム構成信号を出力するフレーム構成部と、 前記第1のマッピング方法を用いてマッピングした複数の変調信号のうち少なくとも1つの変調信号を、前記第1のマッピング方法による変調信号のまま、第1の変調信号として出力し、前記第1のマッピング方法を用いてマッピングした複数の変調信号のうち前記第1の変調信号以外の変調信号を、前記フレーム構成信号に含まれる前記決定されたマッピングパターンを用いて、再度、マッピングした第2の変調信号を出力する信号処理部と、 前記第1の変調信号と前記第2の変調信号とを、それぞれOFDM信号に変換するOFDM変換部と、 前記複数のOFDM信号をそれぞれ、同じ周波数帯域かつ同じタイミングで送信する複数のアンテナと、 を具備し、 前記第1のマッピング方法及び前記第2のマッピング方法は、複数ビットで構成されるビットセットに対応する信号点をマッピングする方法であり、 前記第1のマッピング方法によってIQ平面上の前記複数ビットが第1のビットセットとされる第1の信号点と前記IQ平面上の原点とから構成される直線と、前記IQ平面上のI軸と、から構成される第1の位相と、 前記第2のマッピング方法によってIQ平面上の前記複数ビットが前記第1のビットセットとされる第2の信号点と前記IQ平面上の原点とから構成される直線と、前記IQ平面上のI軸と、から構成される第2の位相と、は、異なる位相であり、 前記第1の信号点と前記原点との距離と、前記第2の信号点と前記原点との距離と、が同じであり、 前記第1ビットセットは、複数ビットがとりうる全ての組み合わせである、 通信装置。
- 2OFDM-MIMO方式の通信を行う通信装置であって、 第1の送信データを変調して第1の変調信号を得る第1の変調手段と、 第2の送信データを変調して第2の変調信号を得る第2の変調手段と、 前記第1及び第2の変調信号を送信する複数のアンテナと を有し、 前記第1の変調手段は、前記第1の送信データの同一データを信号点配置の仕方を変えて複数回変調することにより、同一データから互いに信号点配置の異なる複数の前記第1の変調信号を形成し、 前記第2の変調手段は、信号点配置の仕方を変えずに前記第2の送信データを変調することにより前記第2の変調信号を形成する 、 通信装置。
- 3前記第1の変調手段は、同一データから、同一の変調方式でかつ互いに位相差をもった変調信号を前記第1の変調信号として形成する 、 請求項2に記載の通信装置。
- 4前記第1の変調手段は、同一データから、互いに45°の位相差をもつQPSK変調信号を前記第1の変調信号として形成する 、 請求項3に記載の通信装置。
- 5前記第1の変調手段は、前記第1の送信データを所定の変調方式の信号点位置にマッピングするマッピング部と、マッピングされた信号点の位相を前記同一データの送信回数に応じた角度だけ回転させる位相回転部とを具備する 、 請求項3又は請求項4に記載の通信装置。
- 6所定の変調方式の第1のマッピング方法とは異なる少なくとも1つ以上のマッピングパターンを有する第2のマッピング方法及び前記第1のマッピング方法からマッピングパターンを決定し、前記決定されたマッピングパターンの情報を含むフレーム構成信号を出力するフレーム構成ステップと、 前記第1のマッピング方法を用いてマッピングした複数の変調信号のうち少なくとも1つの変調信号を、前記第1のマッピング方法による変調信号のまま、第1の変調信号として出力し、前記第1のマッピング方法を用いてマッピングした複数の変調信号のうち前記第1の変調信号以外の変調信号を、前記フレーム構成信号に含まれる前記決定されたマッピングパターンを用いて、再度、マッピングした第2の変調信号を出力する信号処理ステップと、 前記第1の変調信号と前記第2の変調信号とを、それぞれOFDM信号に変換するOFDM変換ステップと、 前記複数のOFDM信号をそれぞれ、同じ周波数帯域かつ同じタイミングで、複数のアンテナから送信する送信ステップと、 を含み、 前記第1のマッピング方法及び前記第2のマッピング方法は、複数ビットで構成されるビットセットに対応する信号点をマッピングする方法であり、 前記第1のマッピング方法によってIQ平面上の前記複数ビットが第1のビットセットとされる第1の信号点と前記IQ平面上の原点とから構成される直線と、前記IQ平面上のI軸と、から構成される第1の位相と、 前記第2のマッピング方法によってIQ平面上の前記複数ビットが前記第1のビットセットとされる第2の信号点と前記IQ平面上の原点とから構成される直線と、前記IQ平面上のI軸と、から構成される第2の位相と、は、異なる位相であり、 前記第1の信号点と前記原点との距離と、前記第2の信号点と前記原点との距離と、が同じであり、 前記第1ビットセットは、複数ビットがとりうる全ての組み合わせである、 通信方法。
- 7OFDM-MIMO方式の通信方法であって、 第1の送信データの同一データを、信号点配置の仕方を変えて複数回変調することにより、同一データから互いに信号点配置の異なる複数の変調信号を形成する第1の変調信号形成ステップと、 信号点配置の仕方を変えずに第2の送信データを変調する第2の変調信号形成ステップと 、 を含む通信方法。
- 8前記第1の変調信号形成ステップでは、同一データから、同一の変調方式でかつ互いに位相差をもった複数の変調信号を形成する 、 請求項 7 に記載の通信方法。
- 9前記第1の変調信号形成ステップでは、同一データから、互いに45°の位相差をもつQPSK変調信号を形成する 、 請求項 8 に記載の通信方法。
- 10前記第1の変調信号形成ステップは、 前記第1の送信データを所定の変調方式の信号点位置にマッピングするステップと、 マッピングされた信号点の位相を前記同一データの送信回数に応じた角度だけ回転させるステップと 、 を含む請求項 7 に記載の通信方法。
Independent claims10
535 paragraphs, as filed
The present invention particularly relates to a communication device and a communication method using a multi-antenna.
Conventionally, as a communication method using a multi-antenna, for example, there is a communication method called MIMO (Multiple-Input Multiple-Output). In multi-antenna communication represented by MIMO, the communication speed of data is increased by modulating each of a plurality of series of transmission data and transmitting each modulation signal from different antennas at the same time.
In this type of communication method, it is necessary for the receiving side to separate and demodulate a plurality of modulated signals mixed on the propagation path. Therefore, in communication using a multi-antenna, the demodulation accuracy has a great influence on the substantial data transmission speed.
Conventionally, as a technique for improving the reception quality of a modulated signal on the receiving side and substantially improving the data transmission speed in performing multi-antenna communication, as described in Non-Patent Document 1, for example, a spatiotemporal block Those that transmit the code are known.
This spatiotemporal block code will be briefly described with reference to FIG. As shown in FIG. 1B, the transmitting device has a plurality of antennas 5 and 6, and signals are transmitted from each of the antennas 5 and 6 at the same time. The receiving device receives a plurality of signals transmitted at the same time by the antenna 7.
FIG. 1A shows the frame configuration of the signals transmitted from the antennas 5 and 6. The transmission signal A is transmitted from the antenna 5, and at the same time, the transmission signal B is transmitted from the antenna 6. The transmission signal A and the transmission signal B are composed of a symbol block in which the same symbol is arranged a plurality of times so that a coding gain and a diversity gain can be obtained.
This will be described in more detail. In FIG. 1A, S1 and S2 indicate different symbols, and the complex conjugate is indicated by *. In spatiotemporal block coding, at time point i, the symbol S1 is transmitted from the first antenna 5 and at the same time the symbol -S2 is transmitted from the second antenna 6.<sup>*</sup>Is transmitted, and at the subsequent time point i + 1, the symbol S2 is transmitted from the first antenna 5, and at the same time, the symbol S1 is transmitted from the second antenna 6.<sup>*</sup>To send.
In the antenna 7 of the receiving device, the transmission signal A that receives the transmission line fluctuation h1 (t) between the antenna 5 and the antenna 7 and the transmission signal B that receives the transmission line fluctuation h2 (t) between the antenna 6 and the antenna 7 The combined signal is received.
The receiving device estimates the transmission line fluctuations h1 (t) and h2 (t), and uses the estimated values to separate the original transmission signal A and the transmission signal B from the synthesized reception signal, and then each symbol. Is designed to be demodulated.
At this time, if a spatiotemporal block-coded signal as shown in FIG. 1A is used, the symbols S1 and S2 can be combined at the maximum ratio regardless of the transmission line fluctuations h1 (t) and h2 (t) at the time of signal separation. Therefore, a large coding gain and diversity gain can be obtained. As a result, the reception quality, that is, the error rate characteristic can be improved.<nplcit num="1"><text>Space-Time Block Codes from Orthogonal Design IEEE Transactions on Information Theory, pp.1456-1467, vol.45, no.5, July 1999</text></nplcit>
<p> By the way, as described above, in multi-antenna communication, different modulated signals are transmitted from each transmitting antenna, so that ideally, data transmission is several times as many as the case where the modulated signal is transmitted from one antenna. Achieve speed. However, if the separation / demodulation accuracy of each modulated signal is poor, the actual data transmission speed will decrease.</p><p> On the other hand, if the spatiotemporal block coding technology is used, the reception quality (error rate characteristic) of the modulated signal transmitted from each antenna can be improved, so that the data transmission speed is lowered due to the deterioration of the separation / demodulation accuracy. Can be suppressed.</p><p> However, although the spatiotemporal block coding technique is used, the reception quality (error rate characteristic) is certainly improved, but the transmission efficiency is lowered. That is, S1 transmitted in spatiotemporal block coding<sup>*</sup>And -S2<sup>*</sup>Is demodulated as S1 and S2 in the receiving device, so that the same information is transmitted twice at the time point i and the time point i + 1, and the data transmission efficiency is lowered by this amount.</p><p> For example, in a general multi-antenna communication system, symbols S3 and S4 different from symbols S1 and S2 are transmitted at time point i + 1, so four symbols S1 to S4 are transmitted during the period from time point i to time point i + 1. Can be sent. In other words, simply thinking, when the spatiotemporal block coding technology is used, the data transmission efficiency is reduced to half that of general multi-antenna communication.</p><p> The present invention has been made in view of this point, and an object of the present invention is to provide a communication device and a communication method capable of obtaining excellent reception quality while suppressing a decrease in data transmission efficiency.</p>
<p> In order to solve such a problem, the present invention<u style="single">A mapping pattern is determined from a second mapping method having at least one or more mapping patterns different from the first mapping method of a predetermined modulation method and the first mapping method, and information on the determined mapping pattern is obtained. The frame component unit that outputs the frame component signal including the frame component and at least one of the plurality of modulated signals mapped by the first mapping method are the first modulated signal as the modulated signal by the first mapping method. Of the plurality of modulated signals mapped using the first mapping method, the modulated signals other than the first modulated signal are output as the modulated signals of the above, and the determined mapping pattern included in the frame constituent signal is used. A signal processing unit that outputs the mapped second modulated signal again, an OFDM conversion unit that converts the first modulated signal and the second modulated signal into OFDM signals, and a plurality of the above-mentioned plurality. Each of the OFDM signals includes a plurality of antennas that transmit the same frequency band and the same timing, and the first mapping method and the second mapping method are signals corresponding to a bit set composed of a plurality of bits. It is a method of mapping points, and is a straight line composed of a first signal point in which the plurality of bits on the IQ plane are set as the first bit set by the first mapping method and an origin on the IQ plane. , The first phase composed of the I axis on the IQ plane, and the second signal point in which the plurality of bits on the IQ plane are set as the first bit set by the second mapping method. The straight line composed of the origin on the IQ plane and the second phase composed of the I axis on the IQ plane are in different phases, and the first signal point and the origin are The distance between the second signal point and the origin is the same, and the first bit set is all possible combinations of a plurality of bits.</u>Take the composition.</p><p> As a result, the signal point arrangement of the modulated signal changes every hour or every subcarrier, so that on the receiving side, the Euclidean distance between the candidate signal point and the receiving point is large at a certain time or a certain subcarrier, and there is a certain time or a certain time. In the subcarrier, the Euclidean distance between the candidate signal point and the receiving point becomes small. As a result, the diversity effect can be obtained and the reception quality can be improved.</p><p> Further, in the present invention, the same data of the first transmission data is modulated a plurality of times by changing the method of arranging the signal points to form the first modulated signal, and the second is performed without changing the method of arranging the signal points. The second modulated signal is formed by modulating the transmitted data of.</p><p> As a result, the time with good reception quality or the demodulation result of the first modulated signal obtained based on the received signal of the subcarrier is used as the received digital signal of the first modulated signal, and the time with good reception quality already determined or Received digital signal of the second modulated signal received by the subcarrier at the time of poor reception quality or from the received signal of the subcarrier using the received digital signal of the first modulated signal of the subcarrier. Can be obtained, and the error rate characteristic of the second modulated signal received at a time of poor reception quality or a subcarrier can also be improved. As a result, it is possible to obtain a received digital signal having good error rate characteristics for both the first modulated signal and the second modulated signal.</p><p> Further, in the present invention, since the modulated signal formed from different transmission data is basically transmitted from each antenna, it is possible to suppress a decrease in data transmission efficiency as compared with the case where a spatiotemporal block code is used.</p>
<p> According to the present invention, it is possible to realize a communication device and a communication method capable of obtaining excellent reception quality while suppressing a decrease in data transmission efficiency.</p>
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
(1) Embodiment 1 In the present embodiment, when transmitting different modulated signals from each antenna using the first and second antennas, it is proposed that the same data is transmitted a plurality of times only for one of the modulated signals. In this embodiment, two modulation signals are formed by modulating two different systems of data, and the two modulation signals are transmitted from different antennas. At this time, for the modulated signal transmitted from one of the antennas, the same data is transmitted a plurality of times by changing the method of arranging the signal points. As a result, since different modulation signals are basically transmitted from each antenna, the error rate characteristic of the data transmitted multiple times is improved while keeping the data transmission speed higher than when the spatiotemporal block code is used. As a result, the error rate characteristics of both systems (2 systems) can be improved.
FIG. 2A shows a frame configuration of a modulated signal transmitted from the communication device according to the first embodiment of the present invention. The modulated signal A and the modulated signal B are transmitted from different antennas, respectively. The modulated signals A and B include radio wave propagation environment estimation symbols 101 and 104, respectively. The radio wave propagation environment estimation symbols 101 and 104 are known symbols for estimating the radio wave propagation environment in the receiving device.
102, 103, 105 and 106 represent data symbols. The data symbol 102 (S1 (i)) at time point i and the data symbol 103 (S1 (i)') at time point i + 1 of the modulated signal A are formed by arranging the same data at the signal points with different mapping rules. It was done. On the other hand, the data symbol 105 (S2 (i)) at time point i and the data symbol 106 (S2 (i + 1)) at time point i + 1 of the modulated signal B have different data arranged at signal points according to the same mapping rule. It is a thing. That is, while the modulated signal B is a general modulated signal, the modulated signal A transmits the same data a plurality of times with different mapping patterns.
The modulation signal A is transmitted from the transmission antenna 107 shown in FIG. 2B, and the signal of the modulation signal B is transmitted from the transmission antenna 108. Then, the receiving antennas 109 and 110 receive the combined signal of the modulated signal A and the modulated signal B mixed on the propagation path, respectively.
FIGS. 3A to 3C show an example of signal point arrangement for the modulated signal A. FIG. 3A shows the signal point arrangement of symbol 102 in FIG. 3B and 3C show the signal point arrangement of symbol 103 in FIG. FIG. 3B is an example in which the same data is arranged by rotating the phase by 90 ° with respect to the signal point arrangement of FIG. 3A. Further, FIG. 3C is an example in which the same data is arranged by rotating the phase by 45 ° with respect to the signal point arrangement of FIG. 3A.
FIG. 4 shows a configuration example of the transmission device according to the present embodiment. The transmitters of FIG. 4 include a coding unit 302, a modulation unit 304, a diffusion unit 306, a radio unit 308, a power amplifier 310, a modulation unit 314, a diffusion unit 316, a radio unit 318, and a power amplifier. It is mainly composed of 320 and a frame configuration signal generation unit 323.
In FIG. 4, the frame configuration signal generation unit 323 outputs a signal frame configuration signal 324 indicating the frame configuration, for example, information indicating which of the symbols in the frame is to be transmitted. The coding unit 302 outputs the transmitted digital signal 301 a plurality of times (twice in this embodiment) as a coded digital signal 303 based on the frame configuration signal 324.
The modulation unit 304 takes the encoded digital signal 303 and the frame configuration signal 324 as inputs, and outputs the transmission orthogonal baseband signal 305 to the diffusion unit 306. At this time, the modulation unit 304 maps and modulates the information with a predetermined signal point arrangement as shown in FIG. 3A, and then applies the same information to the signal point arrangement different from the previous time as shown in FIG. 3B or FIG. 3C. Map and modulate with.
The diffusion unit 306 diffuses the transmission orthogonal baseband signal 305 and outputs the diffused transmission orthogonal baseband signal 307 to the radio unit 308. The radio unit 308 converts the diffused transmission orthogonal baseband signal 307 from the baseband frequency to the radio frequency, and outputs the converted modulation signal 309 to the power amplifier 310. The power amplifier 310 amplifies the power of the modulated signal 309 and outputs the amplified modulated signal 311. The modulated signal 311 is output as a radio wave from the antenna 107.
The modulation unit 314 receives the transmission digital signal 313 and the frame configuration signal 324 as inputs, and outputs the transmission orthogonal baseband signal 315. The diffusion unit 316 diffuses the transmission orthogonal baseband signal 315 and outputs the transmission orthogonal baseband signal 317 after diffusion.
The radio unit 318 converts the diffused transmission orthogonal baseband signal 317 from the baseband frequency to the radio frequency, and outputs the converted modulation signal 319. The power amplifier 320 amplifies the power of the modulated signal 319 and outputs the amplified modulated signal 321. The modulated signal 311 is output as a radio wave from the antenna 108.
FIG. 5 shows a configuration example of the modulation unit 304 of FIG. 4 in the present embodiment. In FIG. 5, the mapping unit X402 includes the coded digital signal 401 and the frame configuration signal.<u style="single">324</u>Is used as an input, and the first mapped transmission orthogonal baseband signal 403 is output by mapping the digital signal 401 as shown in FIG. 3A.
The mapping unit Y404 is a coded digital signal 401 and a frame configuration signal.<u style="single">324</u>Is used as an input, and the second mapped transmission orthogonal baseband signal 405 is output by mapping the digital signal 401 with a mapping pattern different from that of the mapping unit X402 as shown in FIG. 3B or FIG. 3C.
The signal selection unit 407 includes a first mapped transmission orthogonal baseband signal 403, a second mapped transmission orthogonal baseband signal 405, and a frame configuration signal.<u style="single">324</u>Is selected as an input, and either the transmission orthogonal baseband signal 403 or 405 is selected based on the frame configuration signal, and the selected transmission orthogonal baseband signal 408 is output.
FIG. 6 shows a configuration example of the receiving device according to the present embodiment. The radio unit 503 receives the reception signal 502 received by the antenna 109 as an input, and outputs the reception orthogonal baseband signal 504. The despreading unit 505 receives the reception quadrature baseband signal 504 as an input and outputs the reception quadrature baseband signal 506 after despreading.
The modulation signal A transmission line estimation unit 507 takes the reception orthogonal baseband signal 506 after despreading as an input, and the transmission line variation of the modulation signal (FIG. 2A) based on the radio wave propagation environment estimation symbol 101 (FIG. 2A) included in the modulation signal A. H11 (t)) in FIG. 2B is estimated, and the estimation result is output as the transmission line estimation signal 508 of the modulation signal A. Similarly, the modulation signal B transmission line estimation unit 509 takes the reception orthogonal baseband signal 506 after despreading as an input, and transmits the modulation signal B based on the radio wave propagation environment symbol 104 (FIG. 2A) included in the modulation signal B. The path variation (h21 (t) in FIG. 2B) is estimated, and the estimation result is output as the transmission path estimation signal 510 of the modulation signal B.
The radio unit 513 receives the reception signal 512 received by the antenna 110 as an input, and outputs the reception orthogonal baseband signal 514. The dediffusion unit 515 receives the reception orthogonal baseband signal 514 as an input, and outputs the reception orthogonal baseband signal 516 after dediffusion.
The modulation signal A transmission line estimation unit 517 takes the reception orthogonal baseband signal 516 after despreading as an input, and the transmission line variation of the modulation signal (FIG. 2A) based on the radio wave propagation environment estimation symbol 101 (FIG. 2A) included in the modulation signal A. H12 (t)) in FIG. 2B is estimated, and the estimation result is output as the transmission line estimation signal 518 of the modulation signal A. Similarly, the modulation signal B transmission line estimation unit 519 receives the reception orthogonal baseband signal 516 after despreading as an input, and transmits the modulation signal B based on the radio wave propagation environment symbol 104 (FIG. 2A) included in the modulation signal B. The path variation (h22 (t) in FIG. 2B) is estimated, and the estimation result is output as the transmission path estimation signal 520 of the modulation signal B.
The frame synchronization unit 521 takes the received orthogonal baseband signals 506 and 516 after despreading as inputs, and synchronizes between frames based on known symbols and the like included in the received orthogonal baseband signals 506 and 516. The configuration signal 522 is formed and output.
The demodulator 523 inputs the transmission path estimation signals 508 and 518 of the modulation signal A, the transmission path estimation signals 510 and 520 of the modulation signal B, the reception orthogonal baseband signals 506 and 516 after despreading, and the frame configuration signal 522. By demodating the received orthogonal baseband signals 506 and 516 using the transmission line estimation signals 508, 518, 510 and 520 and the frame configuration signal 522, the received digital signal 524 of the modulated signal A and the received digital signal 525 of the modulated signal B And output this.
FIG. 7 shows the detailed configuration of the demodulation unit 523. The demodulation unit 523 includes modulation signals A and B demodulation units 608 and modulation signal B demodulation unit 610.
The modulation signals A and B demodulators 608 include transmission path estimation signals 508 and 518 for modulation signal A, transmission path estimation signals 510 and 520 for modulation signal B, reception orthogonal baseband signals 506 and 516 after despreading, and frame configuration signals. The received digital signal 524 and the modulated signal B of the modulated signal A by demoriding the received orthogonal baseband signals 506 and 516 using the transmission path estimation signals 508, 518, 510, 520 and the frame configuration signal 522 with 522 as the input. The received digital signal 525-1 is obtained and output.
The modulation signal B demodulator 610 uses the transmission path estimation signals 508 and 518 of the modulation signal A, the transmission path estimation signals 510 and 520 of the modulation signal B, the reception orthogonal baseband signals 506 and 516 after despreading, and the frame configuration signal 522. In addition, the received digital signal 524 of the modulated signal A obtained by the modulated signals A and B demodulator 608 is used as an input, and the received digital signal 525-2 for the modulated signal B is output using these.
FIG. 8 shows another configuration example of the demodulation unit 523. In FIG. 8, the same reference numerals are given to those that operate in the same manner as in FIG.
The modulation signals A and B demodulators 608 include transmission path estimation signals 508 and 518 for modulation signal A, transmission path estimation signals 510 and 520 for modulation signal B, reception orthogonal baseband signals 506 and 516 after despreading, and frame configuration signals. By using 522 as an input and demolating the received orthogonal baseband signals 506 and 516 using the transmission path estimation signals 508, 518, 510, 520 and the frame configuration signal 522, the received digital signal 524 and the modulated signal B of the modulated signal A The received digital signal 525-1, the first soft judgment value signal 701, and the second soft judgment value signal 702 are obtained and output.
The modulation signal B demodulation unit 703 receives the first soft judgment value signal 701, the second soft judgment value signal 702, and the frame configuration signal 522 as inputs, and inputs the first soft judgment value signal 701 and the second soft judgment value signal. By demodulating the 702, the received digital signal 525-2 of the modulation signal B is obtained and output.
Next, the operation of this embodiment will be described.
As described above, when transmitting the two modulated signals A and B from the antenna, the transmitting device 300 of the present embodiment is the same only for the modulated signal A by changing the mapping pattern (that is, the method of arranging the signal points). Send data multiple times. As a result, compared to the case where the spatiotemporal block code is used, the spatiotemporal block code repeatedly transmits the same information with a plurality of antennas, whereas the transmitting device 300 does not repeatedly transmit the same information from one antenna. In addition, since information is repeatedly transmitted only from the other antenna, the data transmission speed can be kept higher than when the spatiotemporal block code is used.
Further, in the receiving device 500, by receiving such a signal , the modulated signal A and the modulated signal B can be demodulated with good error rate characteristics. This will be explained in detail step by step.
First, the receiver 500 uses the radio wave propagation environment estimation symbol to generate channel fluctuations h11 (t), h12 (t), h21 (t), and h22 (t) between each antenna of each modulated signal at time t. presume. Received signal R1 (i) received by antenna 109 at time i, received signal R2 (i) received by antenna 110, and modulated signal S1 (i) transmitted from antenna 107 at time i, transmitted from antenna 108. The relationship with the modulated signal S2 (i) can be expressed by the following equation using the channel fluctuations h11 (i), h12 (i), h21 (i), and h22 (i).<maths num="1"><img file="JP4445467B2_D0001.tif" /></maths>
Similarly, at time point i + 1, the relational expression of the following equation holds.<maths num="2"><img file="JP4445467B2_D0002.tif" /></maths>
S1 (i) and S2 (i) can be obtained from the relationship of Eq. (1), and S1 (i)'and S2 (i + 1) can be obtained from the relationship of Eq. (2).
Here, when the difference between the time for transmitting the data symbols 102 and 105 and the time for transmitting the data symbols 103 and 106 is small as in the example of FIG. 2A (in the example of FIG. 2A, only the time difference of "1" is different. For (without), h11 (i) h11 (i + 1), h12 (i) h12 (i + 1), h21 (i) h21 (i + 1), h22 (i) h22 (i) +1) holds.
Therefore, in such a case, the matrices of Eqs. (1) and (2) are almost equal, but the vectors of (S1 (i), S2 (i)) and (S1 (i)', S2 Since the vectors of (i + 1)) are different, the certainty of the data obtained by demodulation is different. In particular, Likelihood Detection shown in the document A simple transmit diversity technique for wireless communications, IEEE Journal on Select Areas in Communications, pp.1451-1458, vol.16, no.8, October 1998. When is used, the difference in the certainty of the data becomes large.
An example of the change of the candidate signal point in the received signal at time i and time i + 1 at this time is shown in FIGS. 52A and 52B. FIG. 52A shows the arrangement of candidate signal points in the received signal at time i, and FIG. 52B shows the arrangement of candidate signal points in the received signal at time i + 1. As described above, in the present embodiment, since the arrangement of the candidate signal points is different between the time i and the time i + 1, the reception quality at the time i and the reception quality at the time i + 1 are different. Thereby, the diversity effect can be obtained. The details of FIGS. 52A and 52B will be described later.
The transmitting device 300 and the receiving device 500 of the present embodiment utilize this characteristic to improve the quality of received data.
This will be described in detail. In the transmission device 300, as described above, the same transmission data is modulated so that the signal point arrangement at time i and time i + 1 changes, and the modulation signal A (S1 (i), S1 (i)'). Is formed, and this is transmitted at the same time as the modulated signal B (S2 (i), S2 (i + 1)) using different antennas. As a result, on the receiving side, at time i, the modulated signal S1 (i) and the modulated signal S2 (i) are separated and demolished from the signal in which the modulated signal S1 (i) and the modulated signal S2 (i) are mixed. On the other hand, at time i + 1, the modulated signal S1 (i)'and the modulated signal S2 (i + 1) are obtained from the mixed signal of the modulated signal S1 (i)'and the modulated signal S2 (i + 1). It will be separated and demolished.
Here, since the signal point arrangement of the modulated signal A is changed between the time i and the time i + 1, the signal point position of the mixed signal at the time i and the mixed signal at the time i + 1 The signal point positions are also different, and as a result, the error rate of the received data when they are separated and demodulated is also different.
In the receiving device 500 of the present embodiment, when the reception quality at time i is better, the one obtained by demodulating the modulated signal S1 (i) as the demodulated result of the modulated signal A is used. That is, the demodulation result of S1 (i) is also used as the demodulation result of the modulated signal S1 (i)'. Then, the modulated signal S2 (i) having good reception quality is demodulated by ordinary separation demodulation from the signal in which the modulated signal S1 (i) and the modulated signal S2 (i) are mixed. On the other hand, the modulated signal S2 (i + 1) with poor reception quality is replaced with the modulated signal S1 (i)'with poor reception quality, and the demodulation result of the modulated signal S1 (i) with good reception quality is used. It is designed to be demodulated.
On the other hand, when the reception quality at time i + 1 is better, the demodulated modulation signal S1 (i)'is used as the demodulation result of the modulation signal A. That is, the demodulation result of S1 (i)'is also used as the demodulation result of the modulated signal S1 (i). Then, the modulated signal S2 (i + 1) having good reception quality is demodulated by ordinary separation demodulation from the signal in which the modulated signal S1 (i)'and the modulated signal S2 (i + 1) are mixed. On the other hand, the modulated signal S2 (i) having poor reception quality is replaced with the modulated signal S1 (i) having poor reception quality, and demodulated using the demodulation result of the modulated signal S1 (i)'with good reception quality. It has become like.
In this way, by using the demodulation result of the modulated signal A at a time with good demodulation accuracy, the error rate characteristic at the time of demodulation of the modulated signal A can be improved, and the demodulation signal A at a time with good demodulation accuracy can be demodulated. By demodulating the modulated signal B using the result, the error rate characteristic at the time of demodulating the modulated signal B can also be improved.
The specific demodulation (decoding) procedure of the receiving device 300 is as follows. <1> Detect for time i and obtain (S1 (i), S2 (i)). <2> Detects time i + 1 and obtains (S1 (i)', S2 (i + 1)). <3> Compare the reception quality of time i and time i + 1.
If the reception quality at time i is better, the data (S1 (i), S2 (i)) obtained by the detection at time i is used as it is. Then, the data of S2 (i + 1) is obtained by estimating S1 (i)'at time i + 1 from S1 (i) obtained by the detection at time i and using the result.
On the other hand, when the reception quality at time i + 1 is better, the data obtained by the detection at time i + 1 (S1 (i)', S2 (i + 1)) is used as it is. Then, the data of S2 (i) is obtained by estimating S1 (i) of time i from S1 (i)'obtained by the detection of time i + 1 and using the result.
In the receiving device 500, the demodulation unit 523 performs such demodulation processing to obtain the received digital signal 524 of the modulated signal A and the received digital signal 525 of the modulated signal B.
This demodulation process will be described in more detail.
In the example of this embodiment, since the modulated signal A and the modulated signal B are both QPSK-modulated signals, a total of 4 bits, 2 bits for the modulated signal A and 2 bits for the modulated signal B, can be transmitted at the same time. .. That is, 0000, 0001, ..., 1111 can be transmitted. However, the upper 2 bits are the 2 bits transmitted by the modulation signal A, and the lower 2 bits are the 2 bits transmitted by the modulation signal B.
First, the overall operation of the demodulation unit 523 will be described.
First, at time i, the demodulator 523 uses the transmission line estimation signal 508 of the modulation signal A and the transmission line estimation signal 510 of the modulation signal B to form 16 signal points of 0000, 0001, ..., 1111. Find the signal point (candidate signal point) on the IQ plane. The state of the signal point is shown by reference numeral 1302 in FIG. Further, the demodulation unit 523 inputs a signal at a signal point as shown by reference numeral 1301 in FIG. 14 as a reception orthogonal baseband signal 506 from the reverse diffusion unit 505. Next, the demodulation unit 523 calculates, for example, the square value of the distance from the signal point 1301 in the IQ plane for all the signal points indicated by reference numeral 1302 in FIG. That is, the square value X0000 (i) of the distance between the signal point 1302 of the transmission bit 0000 and the signal point 1301 is obtained, and similarly, the distance between the signal point 1302 and the signal point 1301 of the transmission bits 0001, ..., 1111 is obtained. The squared value of X0001 (i), ..., X1111 (i) is obtained.
Similarly, at time i, the demodulation unit 523 uses the transmission path estimation signal 518 of the modulation signal A and the transmission path estimation signal 520 of the modulation signal B to 16 signal points of 0000, 0001, ..., 1111. Find the signal point (candidate signal point) in the IQ plane of. The state of the signal point is shown by reference numeral 1302 in FIG. Further, the demodulation unit 523 inputs a signal at a signal point as shown by reference numeral 1301 in FIG. 14 as a reception orthogonal baseband signal 516 from the reverse diffusion unit 515. Next, the demodulation unit 523 calculates the square value of the distance from the signal point 1301 in the IQ plane for all the signal points indicated by reference numeral 1302 in FIG. That is, the square value Y0000 (i) of the distance between the signal point 1302 of the transmission bit 0000 and the signal point 1301 is obtained, and similarly, the distance between the signal point 1302 and the signal point 1301 of the transmission bits 0001, ..., 1111 is obtained. The squared value of Y0001 (i), ..., Y1111 (i) is obtained.
Next, the demodulation unit 523 obtains the sum Z0000 (i) = X0000 (i) + Y0000 (i) of X0000 (i) and Y0000 (i), and similarly, Z0001 (i), ..., Z1111 ( i) is calculated. In the same way, the demodulation unit 523 obtains Z0000 (i + 1), Z0001 (i + 1), ..., Z1111 (i + 1) for the time i + 1.
Next, the demodulation unit 523 compares the certainty of the received data between the time i and the time i + 1.
For example, the smallest value is searched from Z0000 (i), Z0001 (i), ..., Z1111 (i). Let that value be F (i). Then search for the second smallest value. Let that value be S (i).
Similarly, the smallest value is searched for from Z0000 (i + 1), Z0001 (i + 1), ..., Z1111 (i + 1). Let that value be F (i + 1). Then search for the second smallest value. Let that value be S (i + 1).
Then, for example, R (i) = F (i) / S (i) and R (i + 1) = F (i + 1) / S (i + 1) are obtained.
When R (i + 1)> R (i), the demodulation unit 523 determines that the reception quality is better at time i, and determines that the 4 bits giving F (i) are correct data. Then, as the 2 bits transmitted by the modulation signal A, the 2 bits obtained at the time i are used as the received data at the time i and the time i + 1. Regarding the modulated signal B, as the 2 bits transmitted at time i, the 2 bits obtained at time i are used as received data as they are, whereas the 2 bits transmitted at time i + 1 are time i + 1. The determination is made by utilizing the fact that the 2 bits transmitted by the modulation signal A in the above have already been determined. For example, if the 2 bits transmitted by the modulation signal A are 00, the highest value among Z0000 (i + 1), Z0001 (i + 1), Z0010 (i + 1), and Z0011 (i + 1). By searching for something that becomes smaller, the 2 bits transmitted by the modulation signal B at time i + 1 are determined. Similarly, if the 2 bits transmitted by the modulation signal A is 01, the most of Z0100 (i + 1), Z0101 (i + 1), Z0110 (i + 1), and Z0111 (i + 1). By searching for a value that becomes smaller, the 2 bits transmitted by the modulation signal B at time i + 1 are determined. Similarly, when the 2 bits transmitted by the modulation signal A are 10 and 11, the 2 bits transmitted by the modulation signal B at the time i + 1 are determined.
When R (i)> R (i + 1), the demodulation unit 523 determines that the reception quality is better at time i + 1, and determines that the 4 bits giving F (i + 1) are correct data. .. Then, as the 2 bits transmitted by the modulation signal A, the 2 bits obtained at the time i + 1 are used as the received data at the time i and the time i + 1. Regarding the modulated signal B, as the 2 bits transmitted at time i + 1, the 2 bits obtained at time i + 1 are used as received data as they are, whereas the 2 bits transmitted at time i are time i. The determination is made by utilizing the fact that the 2 bits transmitted by the modulation signal A in the above have already been determined. For example, if the 2 bits transmitted by the modulation signal A are 00, search for the smallest value among Z0000 (i), Z0001 (i), Z0010 (i), and Z0011 (i). Then, the 2 bits transmitted by the modulation signal B at time i are determined. Similarly, if the 2 bits transmitted by the modulation signal A are 01, search for the smallest value among Z0100 (i), Z0101 (i), Z0110 (i), and Z0111 (i). As a result, the 2 bits transmitted by the modulation signal B at time i are determined. Similarly, when the 2 bits transmitted by the modulation signal A are 10 and 11, the 2 bits transmitted by the modulation signal B at the time i are determined.
Next, the operation when the demodulation unit 523 is configured as shown in FIGS. 7 and 8 will be described.
When the demodulation unit 523 is configured as shown in FIG. 7, the modulation signals A and B demodulation units 608 receive quality of the data transmitted by the modulation signal A at time i and time i + 1 as described above. The demodulated signal from the signal of the better time is output as the received digital signal 524 of the modulated signal A. Further, as described above, the data transmitted by the modulated signal B at a time with good reception quality is output as the received digital signal 525-1 of the modulated signal B.
As described above, the modulation signal B demodulator 610 inputs the received digital signal 524 of the modulated signal A having good reception quality, and by using this, demolishes the modulated signal B at the time when the reception quality is poor. The received digital signal 525-2 of the good quality modulation signal B is obtained and output.
When the demodulation unit 523 is configured as shown in FIG. 8, the modulation signals A and B demodulation units 608 receive the data transmitted by the modulation signal A at time i and time i + 1 as described above. The demodulated signal of good quality time is output as the received digital signal 524 of the modulated signal A. Further, the modulation signals A and B demodulation units 608 output Z0000 (i), ..., Z1111 (i) as the first soft judgment value signal 701, and Z0000 (Z0000 (i) as the second soft judgment value signal 702. i + 1), ..., Z1111 (i + 1) is output. Further, the modulation signal A and B demodulation unit 608 outputs the received digital signal 525-1 of the modulation signal B of either the time i or the time i + 1.
The modulation signal B demodulator 703 includes Z0000 (i), ..., Z1111 (i), which is the first soft judgment value signal 701, and Z0000 (i + 1), which is the second soft judgment value signal 702. ..., Z1111 (i + 1) is input, and as described above, the received digital signal 525-1 is obtained by demodulating the modulated signal B based on the reception quality of time i and time i + 1. The received digital signal 525-2 of the modulated signal B having a time different from that of the modulated signal B is obtained and output.
Thus, according to the present embodiment, among the modulated signals A and B transmitted from different antennas, the modulated signal A is formed by modulating the same data a plurality of times by changing the method of arranging the signal points, and at the same time, the modulated signal. B is formed by sequentially modulating the time series data (that is, forming by applying normal modulation) without modulating the same data multiple times by changing the signal point arrangement, so that the time and space are formed. It is possible to improve the error rate characteristics of the data series transmitted multiple times while keeping the data transmission speed higher than when the block code is used, and as a result, improve the error rate characteristics of both systems (2 systems). Will be able to.
Actually, on the receiving side, the demodulation result of the modulated signal A obtained based on the received signal at the time with good reception quality is used as the received digital signal of the modulated signal A, and the modulated signal A at the time with good reception quality already determined. By using the received digital signal of the above to obtain the received digital signal of the modulated signal B received at the time of the poor reception quality from the received signal of the time of poor reception quality, the signal is received at the time of poor reception quality. The error rate characteristic of the modulated signal B can also be improved.
Further, when QPSK is adopted as the modulation method, for the modulation signal A, QPSK modulation signals having a phase difference of 45 ° from each other are formed from the same data, and if these are transmitted, time i and time i + Since it is possible to obtain a state in which the minimum Euclidean distance is large at 1, the error rate characteristics can be further improved.
(1-1) Modification example 1 In the above-described example, the case where the frame configuration transmitted by the transmission device 300 is as shown in FIG. 2A has been described, but the frame configuration to be transmitted may be as shown in FIG. The difference between the frame configuration of FIG. 9 and the frame configuration of FIG. 2A is that the difference in time for transmitting the signal S1 (i) in which the same data is modulated in the modulated signal A is small in the case of FIG. 2A. , In Fig. 9, it is a very large point.
As a result, the radio wave propagation environment becomes completely different between the time i and the time j. In consideration of this, in the case of FIG. 9, the signal point arrangement of the modulated signal A transmitted at time j is the same as the signal point arrangement of the modulated signal A transmitted at time i. This is because it is considered that the reception quality of time i and time j will be different to some extent due to the difference in the radio wave propagation environment even if the signal point arrangement of the modulated signal A is not changed.
As a result, the demodulation result of the modulated signal A obtained based on the received signal at the time with good reception quality is used as the received digital signal of the modulated signal A, and the received digital signal of the modulated signal A at the time with good reception quality already determined. If the received digital signal of the modulated signal B received at the time of the poor reception quality is obtained from the received signal of the time of the poor reception quality by using the above, it is the same as the case where the signal of the frame configuration of FIG. 2A is transmitted. In addition, the error rate characteristic of the modulated signal B received at a time when the reception quality is poor can also be improved.
This will be described in detail. At time i, the above equation (1) holds. Similarly, at time j, the relation of the following equation holds.<maths num="3"><img file="JP4445467B2_D0003.tif" /></maths>
H11 (j), h12 (j), h21 (j), and h22 (j) in Eq. (3) are estimated by the receiver 500 using, for example, the radio wave propagation environment estimation symbols 801 and 803 in FIG. Here, since the radio wave propagation environment is different between time i and time j, h11 (i) h11 (j), h12 (i) h12 (j), h21 (i) h21 (j), h22 (i). ) h22 (j) holds. Therefore, the reception qualities at time i and time j are completely different.
In consideration of the above, the signal point arrangement in the IQ plane of time i and time j will be described.
An example of signal point arrangement in the IQ plane of the modulated signal A is shown in FIGS. 3A to 3C. When the frame configuration shown in FIG. 9 is adopted, the signal point arrangements of the time i and the time j may be different as shown in FIG. 3A for the time i and FIG. 3A for the time j and as shown in FIG. 3B for the time j. This is different from the frame configuration shown in Fig. 2A. Since the radio wave propagation environment is different between time i and time j, time i and time j do not have to change the signal point arrangement. This is because the reception quality will be different between.
The decoding procedure will be described in detail below, but it can be considered in the same manner as the operation of the frame configuration shown in FIG. 2A. In other words, the operation of time i + 1 should be replaced with time j. <1> Detect for time i and obtain (S1 (i), S2 (i)). <2> Detect for time j and obtain (S1 (i), S2 (j)). <3> Compare the reception quality of time i and time j.
If the reception quality at time i is better, the data (S1 (i), S2 (i)) obtained by the detection at time i is used as it is. Then, the data of S2 (j) is obtained by estimating S1 (i) of time j from S1 (i) obtained by the detection of time i and using the result.
On the other hand, if the reception quality at time j is better, the data obtained by the detection at time j (S1 (i), S2 (j)) is used as it is. Then, the data of S2 (i) is obtained by estimating S1 (i) of time i from S1 (i) obtained by the detection of time j and using the result.
In the receiving device 500, the demodulation unit 523 performs such demodulation processing to obtain the received digital signal 524 of the modulated signal A and the received digital signal 525 of the modulated signal B.
The detailed operation of the demodulation unit 523 when the transmission signal having the frame configuration of FIG. 9 is received is omitted because it is sufficient to replace the operation of the time i + 1 described above with the time j. However, in the above-mentioned processing at time i + 1 and time j, at time i + 1, time i is based on the signal points (candidate signal points) obtained by using the radio wave propagation environment estimation symbols 101 and 104 in FIG. 2A. While the certainty of the data at +1 was judged, at time j, the data at time j was based on the signal points (candidate signal points) obtained using the radio wave propagation environment estimation symbols 801 and 803 in FIG. The difference is that the certainty of is judged.
(1-2) Modification example 2 Here, a case where the frame configuration transmitted by the transmission device 300 is as shown in FIGS. 10A and 10B will be described.
In the frame configuration of FIG. 10A, in short, in the frame configuration of FIG. 2A, the same data was transmitted twice in succession by changing the signal point arrangement method in the modulated signal A, whereas the same data in the modulated signal A was transmitted. Is transmitted three times in a row by changing the method of arranging the signal points.
Further, in the frame configuration of FIG. 10B, in short, in the frame configuration of FIG. 9, the same data was transmitted twice at different times with the modulated signal A without changing the signal point arrangement method, whereas with the modulated signal A, the same data was transmitted twice. The same data is transmitted three times at different times without changing the signal point arrangement.
First, the case where the frame configuration of FIG. 10A is adopted will be described.
The states of time i and i + 1 are the same as those described in the frame configuration of FIG. 2A. At time i + 2, the relationship of the following equation holds.<maths num="4"><img file="JP4445467B2_D0004.tif" /></maths>
Since the time from time i to time i + 2 is short, h11 (i) h11 (i + 1) h11 (i + 2), h12 (i) h12 (i + 1) h12 (i + 2) ), H21 (i) h21 (i + 1) h21 (i + 2), h22 (i) h22 (i + 1) h22 (i + 2).
S1 (i) and S2 (i) can be obtained from the relation of Eq. (1), and S1 (i)'and S2 (i + 1) can be obtained from the relation of Eq. (2). ) , S2 (i + 2) can be obtained from the relation of equations.
At this time, the matrices of Eqs. (1), (2) and (4) are almost equal, but the signal points of S1 (i), S1 (i)'and S1 (i) are changed. Therefore, the vector of (S1 (i), S2 (i)), the vector of (S1 (i)', S2 (i + 1)) and the vector of (S1 (i) , S2 (i + 2)) Is different, so the certainty of the data obtained at each time i ~ i + 2 will be different. At this time, for example, S1 (i) at time i is assigned to the signal point arrangement in FIG. 11A, S1 (i)'at time i + 1 is assigned to the signal point arrangement in FIG. 11B, and S1 (i) at time i + 2 . Is the signal point arrangement shown in Fig. 11C. In this way, by making the signal point arrangement of the modulated signals S1 (i), S1 (i)', S1 (i) of the same data different, each The certainty of the data obtained in time i ~ i + 2 can be changed efficiently.
The transmission signal having the frame configuration of FIG. 10A can be formed by the transmission device 300 having the configuration shown in FIG. The modulation signal 304 may have a configuration in which a mapping unit Z (not shown) is added to the configuration of the modulation unit 304 in FIG. Then, in the added mapping unit Z, the time i + 2 may be mapped.
The specific demodulation (decoding) procedure of the receiving device 300 when the signal having the frame configuration of FIG. 10A is received is as follows. <1> Detect for time i and obtain (S1 (i), S2 (i)). <2> Detects time i + 1 and obtains (S1 (i)', S2 (i + 1)). <3> Time i + 2 is detected and (S1 (i) , S2 (i + 2)) is obtained. <4> Compare the reception quality of time i, time i + 1 and time i + 2.
If the reception quality of time i is the best among time i, time i + 1 and time i + 2, the data obtained by the detection of time i (S1 (i), S2 (i)) is used as it is. Then, the data of S2 (i + 1) is obtained by estimating S1 (i)'at time i + 1 from S1 (i) obtained by the detection at time i and using the result. The data of S2 (i + 2) is obtained by estimating "S1 (i)" of time i + 2 from S1 (i) obtained by the detection of time i and using the result.
If the reception quality at time i + 1 is the best, the data obtained by detection at time i + 1 (S1 (i)', S2 (i + 1)) is used as it is. Then, the data of S2 (i) is obtained by estimating S1 (i) of time i from S1 (i)'obtained by the detection of time i + 1 and using the result. The data of S2 (i + 2) can be obtained by estimating "S1 (i)" of time i + 2 from S1 (i)'obtained by detection of time i + 1 and using the result. To.
Furthermore, when the reception quality of time i + 2 is the best, the data of (S1 (i) , S2 (i + 2)) obtained by the detection of time i + 2 is used as it is, and the data of S2 (i). Estimates S1 (i) at time i from "S1 (i)" obtained by detection at time i + 2, and obtains it by using the result. The data of S2 (i + 1) can be obtained by estimating S1 (i)'of time i + 1 from S1 (i) "obtained by detection of time i + 2 and using the result. To.
In the receiving device 500, the demodulation unit 523 performs such demodulation processing to obtain the received digital signal 524 of the modulated signal A and the received digital signal 525 of the modulated signal B.
This demodulation process will be described in more detail.
When both the modulated signal A and the modulated signal B are QPSK-modulated signals, a total of 4 bits, 2 bits for the modulated signal A and 2 bits for the modulated signal B, can be transmitted at the same time. That is, 0000, 0001, ..., 1111 can be transmitted. However, the upper 2 bits are the 2 bits transmitted by the modulation signal A, and the lower 2 bits are the 2 bits transmitted by the modulation signal B.
First, the overall operation of the demodulation unit 523 will be described.
First, at time i in FIG. 10A, the demodulation unit 523 uses the transmission path estimation signal 508 of the modulation signal A and the transmission path estimation signal 510 of the modulation signal B to form 16 pieces of 0000, 0001, ..., 1111. Find the signal point (candidate signal point) in the IQ plane of the signal point. The state of the signal point is shown by reference numeral 1302 in FIG. Further, the demodulation unit 523 inputs a signal at a signal point as shown by reference numeral 1301 in FIG. 14 as a reception orthogonal baseband signal 506 from the reverse diffusion unit 505. Next, the demodulation unit 523 calculates, for example, the square value of the distance from the signal point 1301 in the IQ plane for all the signal points indicated by reference numeral 1302 in FIG. That is, the square value X0000 (i) of the distance between the signal point 1302 of the transmission bit 0000 and the signal point 1301 is obtained, and similarly, the distance between the signal point 1302 and the signal point 1301 of the transmission bits 0001, ..., 1111 is obtained. The squared value of X0001 (i), ..., X1111 (i) is obtained.
Similarly, at time i in FIG. 10A, the demodulation unit 523 uses the transmission path estimation signal 518 of the modulation signal A and the transmission path estimation signal 520 of the modulation signal B, and 16 pieces of 0000, 0001, ..., 1111. Find the signal point (candidate signal point) in the IQ plane of the signal point of. The state of the signal point is shown by reference numeral 1302 in FIG. Further, the demodulation unit 523 inputs a signal at a signal point as shown by reference numeral 1301 in FIG. 14 as a reception orthogonal baseband signal 516 from the reverse diffusion unit 515. Next, the demodulation unit 523 calculates the square value of the distance from the signal point 1301 in the IQ plane for all the signal points indicated by reference numeral 1302 in FIG. That is, the square value Y0000 (i) of the distance between the signal point 1302 of the transmission bit 0000 and the signal point 1301 is obtained, and similarly, the distance between the signal point 1302 and the signal point 1301 of the transmission bits 0001, ..., 1111 is obtained. The squared value of Y0001 (i), ..., Y1111 (i) is obtained.
Next, the demodulation unit 523 obtains the sum Z0000 (i) = X0000 (i) + Y0000 (i) of X0000 (i) and Y0000 (i), and similarly, Z0001 (i), ..., Z1111 ( i) is calculated. In the same way, the demodulation unit 523 obtains Z0000 (i + 1), Z0001 (i + 1), ..., Z1111 (i + 1) for the time i + 1. Also, for the time i + 2, Z0000 (i + 2), Z0001 (i + 2), ..., Z1111 (i + 2) are obtained.
Next, the demodulation unit 523 compares the certainty of the received data between the time i, the time i + 1, and the time i + 2.
For example, the smallest value is searched from Z0000 (i), Z0001 (i), ..., Z1111 (i). Let that value be F (i). Then search for the second smallest value. Let that value be S (i).
Similarly, the smallest value is searched for from Z0000 (i + 1), Z0001 (i + 1), ..., Z1111 (i + 1). Let that value be F (i + 1). Then search for the second smallest value. Let that value be S (i + 1).
Similarly, the smallest value is searched for from Z0000 (i + 2), Z0001 (i + 2), ..., Z1111 (i + 2). Let that value be F (i + 2). Then search for the second smallest value. Let that value be S (i + 2).
Then, for example, R (i) = F (i) / S (i), R (i + 1) = F (i + 1) / S (i + 1), and R (i + 2) = F. Find (i + 2) / S (i + 2). Using the above values, the reception quality of time i, time i + 1, and time i + 2 is estimated.
When it is judged that the reception quality at time i is the best, the 2 bits transmitted at the modulation signal A are the 2 bits obtained at time i and the received data at time i, time i + 1, and time i + 2. To do. Regarding the modulated signal B, as the 2 bits transmitted at time i, the 2 bits obtained at time i are used as received data as they are, whereas the 2 bits transmitted at time i + 1 and i + 2 are used. Judgment is made by utilizing the fact that the 2 bits transmitted by the modulated signal A at time i + 1 and i + 2 have already been judged.
If it is determined that the reception quality of time i + 1 is the best, the 2 bits transmitted by the modulation signal A are the time i, the time i + 1, and the time i +. It is the received data in 2. Regarding the modulated signal B, as the 2 bits transmitted at time i + 1, the 2 bits obtained at time i + 1 are used as received data as they are, whereas the 2 bits transmitted at time i and i + 2 are used as they are. The bits are determined by utilizing the fact that the 2 bits transmitted by the modulated signal A at time i and i + 2 have already been determined.
Furthermore, if it is determined that the reception quality of time i + 2 is the best, as the 2 bits transmitted by the modulation signal A, the 2 bits obtained at time i + 2 are used as time i, time i + 1, and time i +. It is the received data in 2. Regarding the modulated signal B, as the 2 bits transmitted at time i + 2, the 2 bits obtained at time i + 2 are used as received data as they are, whereas the 2 bits transmitted at time i + 1 are used as they are. The bits are determined by utilizing the fact that the 2 bits transmitted by the modulated signal A at time i and i + 1 have already been determined.
FIG. 12 shows a detailed configuration example of the demodulation unit 523 for performing such processing. As described above, the modulation signal A, B demodulation unit 608 of FIG. 12 is the signal of the time with the best reception quality among the data transmitted by the modulation signal A at time i, time i + 1 and time i + 2. The demodulated signal is output as the received digital signal 524 of the modulation signal A. Further, the modulation signals A and B demodulation units 608 use Z0000 (i), ..., Z1111 (i) as the first soft judgment value signal 701, and Z0000 (i + 1) as the second soft judgment value signal 702. ), ..., Z1111 (i + 1) is output as the third soft judgment value signal 1101, and Z0000 (i + 2), ..., Z1111 (i + 2) is output. Further, the modulation signal A and B demodulation unit 608 outputs the received digital signal 525-1 of the modulation signal B of any one of time i, time i + 1 or time i + 2.
The modulation signal B demodulator 703 includes Z0000 (i), ..., Z1111 (i), which is the first soft judgment value signal 701, and Z0000 (i + 1), which is the second soft judgment value signal 702. ..., Z1111 (i + 1) and Z0000 (i + 2), ..., Z1111 (i + 2), which is the third soft judgment value signal 1101, are input, and as described above, the time Receiving the modulated signal B at a time different from the modulated signal B obtained by obtaining the received digital signal 525-1 by demodulating the modulated signal B based on the reception quality of i, time i + 1 and time i + 2. Obtain the digital signal 525-2 and output it.
In this way, when the frame configuration as shown in FIG. 10A is used, the time with the best reception quality is set in a larger amount of time as compared with the case where the frame configuration as shown in FIG. 2A is used. Since it becomes possible to select from, it becomes possible to obtain the demodulated data of the modulated signals A and B having better error rate characteristics.
Here, as shown in FIG. 10A, the case where the same data is transmitted with three consecutive symbols S1 (i), S1 (i)', S1 (i) with different signal point arrangements has been described. The point is that when a modulated signal of the same data is transmitted multiple times at short time intervals, the reception quality at each time is changed by changing the signal point arrangement of the modulated signal of the same data. That is, the modulated signal transmitted at time i, i + 1, i + 2 may be transmitted at time i, i + n, i + m. At this time, h11 ( i) h11 (i + n) h11 (i + m), h12 (i) h12 (i + n) h12 (i + m), h21 (i) h21 (i + n) h21 ( It is effective if the relationship of i + m) and h22 (i) h22 (i + n) h22 (i + m) is established. In this case, the above-mentioned operation of time i + 1 is performed by time i +. As the operation of n, if the operation of time i + 2 is considered as time i + m, it can be carried out in the same manner.
Next, the case where the frame configuration of FIG. 10B is adopted will be described.
Further, as described above, in the frame configuration of FIG. 10B, in short, in the frame configuration of FIG. 9, the same data was transmitted twice at different times without changing the signal point arrangement in the modulated signal A, whereas the modulation signal A was modulated. At signal A, the same data is transmitted three times at different times without changing the signal point arrangement.
The states of time i and j are the same as those described in the frame configuration of FIG. At time k, the relationship of the following equation holds.<maths num="5"><img file="JP4445467B2_D0005.tif" /></maths>
Here, since the times i, j, and k are times in which the radio wave propagation environment is different, h11 (i) h11 (j) h11 (k), h12 (i) h12 (j) h12 ( k), h21 (i) h21 (j) h21 (k), h22 (i) h22 (j) h22 (k). Therefore, the reception quality at time i, j, and k will be completely different. In consideration of this, in the case of FIG. 10B, the signal point arrangement of the modulated signal A transmitted at time j and time k is the same as the signal point arrangement of the modulated signal A transmitted at time i. This is because we thought that the reception quality of time i, time j, and time k would differ to some extent due to the difference in the radio wave propagation environment, even if the signal point arrangement of the modulated signal A was not changed.
An example of signal point arrangement in the IQ plane of the modulated signal A is shown in FIGS. 11A to 11C. When the frame configuration shown in FIG. 10B is adopted, the signal point arrangements at time i, j, and k may all be as shown in FIG. 11A, as shown in FIG. 11A at time i, FIG. 11B at time j, and FIG. 11C at time k. It may be different. This is because the radio wave propagation environment is different at times i, j, and k, so that the reception quality at each time is different even if the signal point arrangement is not intentionally changed at each time.
The specific demodulation (decoding) procedure of the receiving device 300 when the signal having the frame configuration of FIG. 10B is received is as follows. <1> Detect for time i and obtain (S1 (i), S2 (i)). <2> Detect for time j and obtain (S1 (i), S2 (j)). <3> Detect for time k to obtain (S1 (i), S2 (k)). <4> Compare the reception qualities of time i, time j and time k.
If the reception quality of time i is the best among time i, time j and time k, the data obtained by the detection of time i (S1 (i), S2 (i)) is used as it is. Then, the data of S2 (j) is obtained by estimating S1 (i) of time j from S1 (i) obtained by the detection of time i and using the result. The data of S2 (k) is obtained by estimating S1 (i) of time k from S1 (i) obtained by the detection of time i and using the result.
If the reception quality at time j is the best, the data obtained by the detection at time j (S1 (i), S2 (j)) is used as it is. Then, the data of S2 (i) is obtained by estimating S1 (i) of time i from S1 (i) obtained by the detection of time j and using the result. The data of S2 (k) is obtained by estimating S1 (i) of time k from S1 (i) obtained by the detection of time j and using the result.
Furthermore, when the reception quality at time k is the best, the data (S1 (i), S2 (k)) obtained by the detection at time k is used as it is. Then, the data of S2 (i) is obtained by estimating S1 (i) of time i from S1 (i) obtained by the detection of time k and using the result. The data of S2 (j) is obtained by estimating S1 (i) of time j from S1 (i) obtained by the detection of time k and using the result.
In the receiving device 500, the demodulation unit 523 performs such demodulation processing to obtain the received digital signal 524 of the modulated signal A and the received digital signal 525 of the modulated signal B.
This demodulation process will be described in more detail.
When both the modulated signal A and the modulated signal B are QPSK-modulated signals, a total of 4 bits, 2 bits for the modulated signal A and 2 bits for the modulated signal B, can be transmitted at the same time. That is, 0000, 0001, ..., 1111 can be transmitted. However, the upper 2 bits are the 2 bits transmitted by the modulation signal A, and the lower 2 bits are the 2 bits transmitted by the modulation signal B.
First, the overall operation of the demodulation unit 523 will be described.
First, at time i in FIG. 10B, the demodulation unit 523 uses the transmission path estimation signal 508 of the modulation signal A and the transmission path estimation signal 510 of the modulation signal B to form 16 pieces of 0000, 0001, ..., 1111. Find the signal point (candidate signal point) in the IQ plane of the signal point. The state of the signal point is shown by reference numeral 1302 in FIG. Further, the demodulation unit 523 inputs a signal at a signal point as shown by reference numeral 1301 in FIG. 14 as a reception orthogonal baseband signal 506 from the reverse diffusion unit 505. Next, the demodulation unit 523 calculates, for example, the square value of the distance from the signal point 1301 in the IQ plane for all the signal points indicated by reference numeral 1302 in FIG. That is, the square value X0000 (i) of the distance between the signal point 1302 of the transmission bit 0000 and the signal point 1301 is obtained, and similarly, the distance between the signal point 1302 and the signal point 1301 of the transmission bits 0001, ..., 1111 is obtained. The squared value of X0001 (i), ..., X1111 (i) is obtained.
Similarly, at time i in FIG. 10B, the demodulation unit 523 uses the transmission path estimation signal 518 of the modulation signal A and the transmission path estimation signal 520 of the modulation signal B, and 16 pieces of 0000, 0001, ..., 1111. Find the signal point (candidate signal point) in the IQ plane of the signal point of. The state of the signal point is shown by reference numeral 1302 in FIG. Further, the demodulation unit 523 inputs a signal at a signal point as shown by reference numeral 1301 in FIG. 14 as a reception orthogonal baseband signal 516 from the reverse diffusion unit 515. Next, the demodulation unit 523 calculates the square value of the distance from the signal point 1301 in the IQ plane for all the signal points indicated by reference numeral 1302 in FIG. That is, the square value Y0000 (i) of the distance between the signal point 1302 of the transmission bit 0000 and the signal point 1301 is obtained, and similarly, the distance between the signal point 1302 and the signal point 1301 of the transmission bits 0001, ..., 1111 is obtained. The squared value of Y0001 (i), ..., Y1111 (i) is obtained.
Next, the demodulation unit 523 obtains the sum Z0000 (i) = X0000 (i) + Y0000 (i) of X0000 (i) and Y0000 (i), and similarly, Z0001 (i), ..., Z1111 ( i) is calculated. In the same way, the demodulation unit 523 obtains Z0000 (j), Z0001 (j), ..., Z1111 (j) for the time j. Also, for the time k, find Z0000 (k), Z0001 (k), ..., Z1111 (k).
Next, the demodulation unit 523 compares the certainty of the received data between the time i, the time j, and the time k.
For example, the smallest value is searched from Z0000 (i), Z0001 (i), ..., Z1111 (i). Let that value be F (i). Then search for the second smallest value. Let that value be S (i).
Similarly, the smallest value is searched for from Z0000 (j), Z0001 (j), ..., Z1111 (j). Let that value be F (j). Then search for the second smallest value. Let that value be S (j).
Similarly, the smallest value is searched for from Z0000 (k), Z0001 (k), ..., Z1111 (k). Let that value be F (k). Then search for the second smallest value. Let that value be S (k).
Then, for example, R (i) = F (i) / S (i), R (j) = F (j) / S (j), and R (k) = F (k) / S (k). Ask for. Using the above values, the reception quality at time i, time j, and time k is estimated.
When it is determined that the reception quality at time i is the best, the 2 bits obtained at time i are used as the received data at time i, time j, and time k as the 2 bits transmitted by the modulation signal A. Regarding the modulated signal B, as the 2 bits transmitted at time i, the 2 bits obtained at time i are used as received data as they are, whereas the 2 bits transmitted at time j and k are time j and k. The determination is made by utilizing the fact that the 2 bits transmitted by the modulation signal A in the above have already been determined.
When it is determined that the reception quality at time j is the best, the 2 bits obtained at time j are used as the received data at time i, time j, and time k as the 2 bits transmitted by the modulation signal A. Regarding the modulated signal B, as the 2 bits transmitted at time j, the 2 bits obtained at time j are used as received data as they are, whereas the 2 bits transmitted at times i and k are used at times i and k. The determination is made by utilizing the fact that the 2 bits transmitted by the modulation signal A in the above have already been determined.
Further, when it is determined that the reception quality at time k is the best, the 2 bits obtained at time k are used as the received data at time i, time j, and time k as the 2 bits transmitted by the modulation signal A. Regarding the modulated signal B, as the 2 bits transmitted at time k, the 2 bits obtained at time k are used as received data as they are, whereas the 2 bits transmitted at times i and j are used at times i and j. The determination is made by utilizing the fact that the 2 bits transmitted by the modulation signal A in the above have already been determined.
FIG. 12 shows a detailed configuration example of the demodulation unit 523 for performing such processing. As described above, the modulation signal A, B demodulation unit 608 of FIG. 12 demodulates the data transmitted by the modulation signal A at time i, time j, and time k from the signal of the time with the best reception quality. Is output as the received digital signal 524 of the modulated signal A. Further, the modulation signals A and B demodulation units 608 use Z0000 (i), ..., Z1111 (i) as the first soft judgment value signal 701, and Z0000 (j) as the second soft judgment value signal 702. ..., Z1111 (j) is used as the third soft judgment value signal 1101, and Z0000 (k), ..., Z1111 (k) are output. Further, the modulation signal A, B demodulation unit 608 outputs the received digital signal 525-1 of the modulation signal B of any one of time i, time j, and time k.
The modulation signal B demodulator 703 includes Z0000 (i), ..., Z1111 (i), which is the first soft judgment value signal 701, and Z0000 (j), which is the second soft judgment value signal 702., Z1111 (j) and Z0000 (k), ..., Z1111 (k), which are the third soft judgment value signals 1101, are input, and as described above, the time i, the time j, and the time k By demodulating the modulated signal B based on the reception quality, the received digital signal 525-2 of the modulated signal B at a time different from that obtained the received digital signal 525-1 is obtained and output. To do.
In this way, when the frame configuration as shown in FIG. 10B is used, the time with the best reception quality is set in a larger amount of time as compared with the case where the frame configuration as shown in FIG. 9 is used. Since it becomes possible to select from, it becomes possible to obtain the demodulated data of the modulated signals A and B having better error rate characteristics.
(1-3) Modification 3 Here, an example is given in which the frame configuration transmitted by the transmission device 300 is shown in FIG. 13 instead of FIG. 2A. The difference between the frame configuration of FIG. 13 and the frame configuration of FIG. 2A is that the difference in the time for transmitting the signals S1 (i) and S1 (i)'modulated with the same data in the modulated signal A is different in the case of FIG. 2A. Whereas it was set to "1", it was set to "n" in FIG.
Here, h11 (i) h11 (i + n), h12 (i) h12 (i + n), h21 (i) h21 (i + n), h22 (i) h22 (i + n) If n such that the relationship of is established, it can be carried out in the same manner as when the signal of the frame configuration of FIG. 2A is transmitted. That is, if the operation of time i + 1 is considered as the operation of time i + n, it can be carried out in the same manner.
(1-4) Modification example 4 Here, it is proposed that the transmission power of the modulation signal A or the transmission power of the modulation signal B be different between the time i and the time i + 1. By doing so, the reception quality can be changed between the time i and the time i + 1 in the same manner as when the pattern of the signal point arrangement of the modulated signal A described above is changed between the time i and the time i + 1. Therefore, the same effect as when the above-mentioned frame configuration is adopted can be obtained. Further, when combined with the frame configuration described above, the difference in reception quality at each time can be further increased. That is, changing the method of arranging the signal points includes changing the transmission power.
Specifically, at time i, the modulation signals S1 (i) and S2 (i) for which equation (1) holds are transmitted, and at time i + 1, the modulation that holds equation (6) or (7) below holds. The signal rS1 (i)', S2 (i + 1) or the modulated signal S1 (i)', rS2 (i + 1) is transmitted.<maths num="6"><img file="JP4445467B2_D0006.tif" /></maths><maths num="7"><img file="JP4445467B2_D0007.tif" /></maths>
The difference between Eqs. (6) and (7) is whether the transmission power of the modulated signal A (S1) is changed or the transmission power of the modulated signal B (S2) is changed. In this way, changing the transmission power to change the reception quality can also be carried out in combination with the following embodiments.
(1-5) Modification example 5 The configuration of the transmitter is not limited to the configuration shown in FIG. 4, and the configuration of the modulation unit 304 is not limited to the configuration shown in FIG. The point is that a first modulation unit and a second modulation unit are provided, and the same data of the first transmission data is distributed by the first modulation unit by changing the way of arranging the signal points, or at intervals of several symbols. The first modulation signal is formed by modulation once, and the second modulation signal is formed by modulating the second transmission data in time series by the second modulation unit, and the first and second modulation signals are formed. The modulated signal may be transmitted from different antennas.
Further, the configuration of the receiving device is not limited to the configuration shown in FIG. 6, and the configuration of the demodulation unit 523 is not limited to the configurations shown in FIGS. 6, 7, and 8. In short, the demodulation result of the modulated signal A (that is, the modulated signal transmitted by modulating the same data multiple times) obtained based on the received signal at a time with good reception quality is used as the received digital signal of the modulated signal A, and is also used. The received digital signal of the modulated signal B received at the time of poor reception quality is obtained from the received signal of the time of poor reception quality by using the received digital signal of the modulated signal A of the time of good reception quality already determined. do it.
Further, each antenna may be composed of a plurality of antennas to form one antenna. Further, in the above-described embodiment, the case where the number of modulated signals and the number of antennas are the same has been described, but more antennas than the number of modulated signals n (n 2) are provided, and the transmitting antennas are switched for use. You may. In this way, by switching the transmitting antenna, the reception quality at each time can be further changed. This also applies to the embodiments described below.
Further, in the above-described embodiment, as a calculation formula for obtaining the reception quality, for example, R (i) = F (i) / S (i), R (i + 1) = F (i + 1) / S. (i + 1), R (i + 2) = F (i + 2) / S (i + 2), R (j) = F (j) / S (j), R (k) = F (k) ) / S (k) has been described, but it is not limited to this, for example, R (i) = F (i) S (i), R (i + 1) = F (i). +1) S (i + 1), R (i + 2) = F (i + 2) S (i + 2), R (j) = F (j) S (j), R (k The reception quality can be obtained in the same manner by using a calculation formula such as) = F (k) S (k). This also applies to embodiments described below. However, when such a calculation formula is used, the magnitude relationship is opposite to that described in the embodiment. In other words, the larger R (i), the better the reception quality.
Further, in the above-described embodiment, a frame configuration in which the same data is transmitted twice and a frame configuration in which the same data is transmitted three times with the modulation signal A are proposed, but the present invention is not limited to this, and the same data is transmitted with the modulation signal A n (n 4). The same can be applied to the frame configuration in which the data is transmitted multiple times. Here, as the number of n is increased, the apparent data transmission speed that can be transmitted by the modulated signal A decreases, but the error rate characteristics when the modulated signals A and B are demodulated are improved, so that the radio wave propagation environment is improved. The worse, the more n is set, the more the actual data transmission speed can be increased.
Further, in the above-described embodiment, the case where the spectrum diffusion method is used has been described as an example, but the present invention is not limited to this, and the same can be applied to the single carrier method which does not perform spectrum diffusion. At this time, the transmitting device may have a configuration in which the diffusion unit is omitted, and the receiving device may have a configuration in which the back diffusion unit is omitted. Further, even in the multi-carrier system using the OFDM system as an example, the coding of the present implementation can be applied to each carrier. For example, when the OFDM method is used, the transmitting device may have a configuration in which an inverse Fourier transform unit is added to generate a modulated signal using the OFDM method, and the receiving device may have a configuration in which a Fourier transform unit is added. This also applies to embodiments described below.
Further, in the above-described embodiment, the modulation signal A and the modulation signal B are coded in the time axis direction. That is, in the example of the above-described embodiment, in the modulated signal A, the modulated signals of the same data are transmitted at different times. However, the coding of the present embodiment (arrangement of the modulated signal in the transmission frame) can be performed in the frequency axis direction, particularly when the multi-carrier method using the OFDM method as an example is used. That is, it suffices that the modulation signal A has a plurality of symbols of the same data arranged on different carriers.
Further, in the above-described embodiment, the reception quality (error rate characteristic) of the modulated signal B is also improved by improving the reception quality (error rate characteristic) of the modulated signal A. In addition to the above-described embodiment, if the modulation signal A is encoded by a block code, a convolutional code such as a bitabi code or a turbo code, an LDPC (Low-Density Parity-Check) code, or the like. Since the reception quality of the reception signal A can be further improved, the reception quality of the modulated signal B can also be further improved. This also applies to embodiments described below.
However, the block code, the convolutional code such as the Viterbi code and the turbo code, and the error correction code such as the LDPC code are not limited to the case where they are applied only to the modulation signal A, and may be applied to both the modulation signals A and B. In this case, after decoding the modulated signal A, the modulated signal B is decoded.
Further, in the above-described embodiment, a configuration in which two modulated signals are transmitted from two antennas has been described as an example, but the present invention is not limited to this, and a frame configuration in which n modulated signals are transmitted from n antennas is described. In the above, at least one of the n modulated signals may be transmitted with the same data a plurality of times using different frequencies or different times. This also applies to embodiments described below.
(2) Embodiment 2 In the first embodiment, when transmitting two different modulated signals using two antennas, it is proposed that the same data is transmitted a plurality of times only for one of the modulated signals. On the other hand, in the present embodiment, when transmitting three different modulated signals using the three antennas, the same data is transmitted a plurality of times for one or two modulated signals out of the three modulated signals. In addition to proposing that, the specific frame configuration and device configuration will be described.
FIG. 15, which is shown by assigning the same reference numerals to the portions corresponding to those in FIG. 2A, shows an example of the frame configuration of the modulated signal in the present embodiment. In the present embodiment, the modulation signal C is transmitted at the same time as the modulation signal A and the modulation signal B. The modulated signal C includes the radio wave propagation environment estimation symbol 1401. 1402 and 1403 indicate data symbols. The data symbol 1402 (S3 (i)) at time point i and the data symbol 1403 (S3 (i + 1)) at time point i + 1 of the modulated signal C have the same mapping rules for different data as well as the modulated signal B. The signal points are arranged according to the above. That is, only the modulated signal A is a special signal in which the same data is transmitted a plurality of times by changing the signal point arrangement method, and the modulated signals B and C are general modulated signals.
FIG. 17 shows the relationship between the transmitting antennas 1601, 1602, 1603, the receiving antennas 1604, 1605, and 1606 according to the present embodiment, and the propagation paths between these transmitting and receiving antennas.
FIG. 18, which is shown by assigning the same reference numerals to the portions corresponding to those in FIG. 4, shows a configuration example of the transmission device according to the present embodiment. In the transmission device 1700, the modulation unit 1702 receives the transmission digital signal 1701 and the frame configuration signal 324 as inputs, and outputs the transmission orthogonal baseband signal 1703. The diffusion unit 1704 diffuses the transmission orthogonal baseband signal 1703 and outputs the transmission orthogonal baseband signal 1705 after diffusion.
The radio unit 1706 converts the transmitted orthogonal baseband signal 1705 after diffusion from the baseband frequency to the radio frequency, and outputs the converted modulation signal 1707. The power amplifier 1708 amplifies the power of the modulated signal 1707 and outputs the amplified modulated signal 1709. The modulated signal 1709 is output as a radio wave from the antenna 1603.
FIG. 19, which is shown by assigning the same reference numerals to the portions corresponding to those in FIG. 6, shows a configuration example of the receiving device according to the present embodiment. In the receiving device 1800, the radio unit 1803 receives the received signal 1802 received by the antenna 1606 as an input and outputs the receiving orthogonal baseband signal 1804. The despreading unit 1805 receives the reception quadrature baseband signal 1804 as an input and outputs the reception quadrature baseband signal 1806 after despreading.
The modulation signal A transmission line estimation unit 1807 receives the reception orthogonal baseband signal 1806 after despreading as an input, and outputs the transmission line estimation signal 1808 of the modulation signal A. The modulation signal B transmission line estimation unit 1809 receives the reception orthogonal baseband signal 1806 after despreading as an input, and outputs the transmission line estimation signal 1810 of the modulation signal B.
The modulation signal C transmission line estimation unit 1811 receives the reception orthogonal baseband signal 1806 after despreading as an input, and outputs the transmission line estimation signal 1812 of the modulation signal C. The modulation signal C transmission line estimation unit 1813 receives the reception orthogonal baseband signal 506 after despreading as an input, and outputs the transmission line estimation signal 1814 of the modulation signal C. The modulation signal C transmission line estimation unit 1815 receives the reception orthogonal baseband signal 516 after despreading as an input, and outputs the transmission line estimation signal 1816 of the modulation signal C.
The frame synchronization unit 521 inputs the received orthogonal baseband signals 506, 516, and 1806 after each reverse diffusion, and outputs the frame configuration signal 522.
The demodulator 1820 includes reception orthogonal baseband signals 506, 516, 1806 after despreading, transmission path estimation signals 508, 518, 1808 for modulation signal A, transmission path estimation signals 510, 520, 1810 for modulation signal B, and modulation signals. By using the transmission path estimation signals 1812, 1814, 1816 of C and the frame configuration signal 522 as inputs and demolating the modulated signal A, the modulated signal B, and the modulated signal C, the received digital signal 524 of the modulated signal A and the modulated signal B are performed. The received digital signal 525 of the above and the received digital signal 1817 of the modulated signal C are obtained and output.
FIG. 20 shows the detailed configuration of the demodulation unit 1820. The modulation signal A, B, C demodulator 1913 includes transmission path estimation signals 508, 518, 1808 for modulation signal A, transmission path estimation signals 510, 520, 1810 for modulation signal B, and transmission path estimation signals 1814 for modulation signal C. 1816, 1812, received orthogonal baseband signals 506, 516, 1806 after despreading, frame configuration signal 522 are input, received digital signal 524 of modulated signal A, received digital signal 525-1 of modulated signal B, modulated signal C The received digital signal 1817-1, the first soft judgment value signal 1917, and the second soft judgment value signal 1918 are output.
The modulation signal B, C demodulator 1919 receives the first soft judgment value signal 1917, the second soft judgment value signal 1918, and the frame configuration signal 522 as inputs, and receives the modulation signal B, the received digital signal 525-2, and the modulation signal C. Outputs the received digital signal 1817-2.
Next, the operation of this embodiment will be described.
As described above, in the transmission device 1700 of the present embodiment, when transmitting the three modulation signals A, B, and C from the antenna, the mapping pattern is changed only for the modulation signal A (the method of arranging the signal points is changed). Send the same data multiple times. As a result, compared to the case where the spatiotemporal block code is used, the spatiotemporal block code repeatedly transmits the same information by multiple antennas, whereas the transmitter 1700 transmits data from only one of the three antennas. Since the data is transmitted repeatedly, the data transmission speed can be kept higher than when the spatiotemporal block code is used.
Further, in the receiving device 1800, by receiving such a signal, all of the modulated signals A, B, and C can be demodulated with good error rate characteristics. That is, when such a signal is received, the signal point arrangement of the received modulated signal changes between time i and time i + 1, so that the accuracy of demodulation of the modulated signal A, the modulated signal B, and the modulated signal C at time i , The accuracy of the demodulation of the modulated signal A, the modulated signal B, and the modulated signal C at time i + 1 becomes different. Then, the modulated signal A is demodulated at a time with good demodulation accuracy, and the result is used to demodulate the modulated signal B and the modulated signal C to improve the demodulation accuracy of the modulated signal B and the modulated signal C. be able to.
The operation of the receiver 1800 will be described in detail.
First, the receiving device 1800 estimates the channel variation between the transmitting and receiving antennas by using the radio wave propagation environment estimation symbol. Here, when there is a relationship between the transmitting and receiving antennas in FIG. 17, if the channel variation from the transmitting antenna i to the receiving antenna j is represented by hji and the receiving signal of the receiving antenna j is Rj, the relational expression of the transmitted and received signals at time i is It can be expressed as the following equation.<maths num="8"><img file="JP4445467B2_D0008.tif" /></maths>
Similarly, at time i + 1, the following relationship holds.<maths num="9"><img file="JP4445467B2_D0009.tif" /></maths>
From the relation of Eq. (8), S1 (i), S2 (i), S3 (i) can be obtained, and from the relation of Eq. (9), S1 (i)', S2 (i + 1), S3 ( i + 1) can be obtained.
Similar to the first embodiment, h11 (i) h11 (i + 1), h12 (i) h12 (i + 1), h13 (i) h13 (i + 1), h21 (i) h21 (i + 1), h22 (i) h22 (i + 1) h23 (i) h23 (i + 1), h31 (i) h31 (i + 1), h32 (i) h32 (i +) 1) h33 (i) h33 (i + 1) holds.
At this time, the matrices of Eqs. (8) and (9) are almost equal, but the vectors of (S1 (i), S2 (i), S3 (i)) and (S1 (i)', S2 Since the vectors of (i + 1) and S3 (i + 1)) are different, the certainty of the obtained data will be different.
The transmitting device 1700 and the receiving device 1800 of the present embodiment utilize this characteristic to improve the quality of received data.
The specific demodulation (decoding) procedure of the receiving device 1800 is as follows. <1> Detect for time i and obtain (S1 (i), S2 (i), S3 (i)). <2> Detects time i + 1 and obtains (S1 (i)', S2 (i + 1), S3 (i + 1)). <3> Compare the reception quality of time i and time i + 1.
If the reception quality at time i is better, the data obtained by detection at time i (S1 (i), S2 (i), S3 (i)) is used as it is. Then, S1 (i)'at time i + 1 is estimated from S1 (i) obtained by detection at time i, and the results are used to obtain S2 (i + 1) and S3 (i + 1). ..
If the reception quality at time i + 1 is better, the data obtained by detection at time i + 1 (S1 (i)', S2 (i + 1), S3 (i + 1)) is used as it is. Then, S1 (i) at time i is estimated from S1 (i)'obtained by detection at time i + 1, and the results are used to obtain S2 (i) and S3 (i).
In the receiving device 1800, the demodulation unit 1820 performs such demodulation processing to obtain the received digital signal 524 of the modulated signal A, the received digital signal 525 of the modulated signal B, and the received digital signal 1817 of the modulated signal C.
In the example of this embodiment, since the modulation signal A, the modulation signal B, and the modulation signal C are all QPSK-modulated signals, the modulation signal A has 2 bits, the modulation signal B has 2 bits, and the modulation signal C has the same time. A total of 6 bits, 2 bits, can be transmitted. That is, 000000,000001, ..., 111111 can be transmitted. However, the upper 2 bits are the 2 bits transmitted by the modulation signal A, the middle 2 bits are the modulation signal B, and the lower 2 bits are the 2 bits transmitted by the modulation signal C.
First, the overall operation of the demodulation unit 1820 will be described.
First, at time i in FIG. 15, the demodulator 1820 uses the transmission path estimation signal 508 of the modulation signal A, the transmission path estimation signal 510 of the modulation signal B, and the transmission path estimation signal 1814 of the modulation signal C, and 000000,000001, ..., Find the signal points (candidate signal points) in the IQ plane of 64 signal points of 111111. Further, the demodulation unit 1820 inputs the reception orthogonal baseband signal 506 after despreading from the despreading unit 505, and obtains the reception state (reception signal point) in the IQ plane from the reception orthogonal baseband signal 506.
Next, the demodulator 1820 calculates, for example, the square value of the distance from the received signal point in the IQ plane for all 64 signal points. That is, the square value X000000 (i) of the distance between the signal point of the transmission bit 000000 and the reception signal point is obtained, and similarly, the distance 2 of the distance between the signal point of the transmission bit 000001, ..., 111111 and the reception signal point is obtained. Find the multiplier X000001 (i), ..., X111111 (i).
Similarly, at time i in FIG. 15, the demodulator 1820 uses the transmission path estimation signal 518 of the modulation signal A, the transmission path estimation signal 520 of the modulation signal B, and the transmission path estimation signal 1816 of the modulation signal C to 000000, Find the signal points (candidate signal points) in the IQ plane of 64 signal points of 000001, ..., 111111. Further, the demodulation unit 1820 inputs the reception orthogonal baseband signal 516 after despreading from the despreading unit 515, and obtains the reception state (reception signal point) in the IQ plane from the reception orthogonal baseband signal 516.
Next, the demodulator 1820 calculates, for example, the square value of the distance from the received signal point in the IQ plane for all 64 signal points. That is, the square value Y000000 (i) of the distance between the signal point of the transmission bit 000000 and the reception signal point is obtained, and similarly, the distance 2 of the distance between the signal point of the transmission bit 000001, ..., 111111 and the reception signal point is obtained. Find the multipliers Y000001 (i), ..., Y111111 (i).
Similarly, at time i in FIG. 15, the demodulator 1820 uses the transmission path estimation signal 1808 of the modulation signal A, the transmission path estimation signal 1810 of the modulation signal B, and the transmission path estimation signal 1812 of the modulation signal C to 000000, Find the signal points (candidate signal points) in the IQ plane of 64 signal points of 000001, ..., 111111. Further, the demodulation unit 1820 inputs the reception orthogonal baseband signal 1806 after despreading from the despreading unit 1805, and obtains the reception state (reception signal point) in the IQ plane from the reception orthogonal baseband signal 1806.
Next, the demodulator 1820 calculates, for example, the square value of the distance from the received signal point in the IQ plane for all 64 signal points. That is, the square value Z000000 (i) of the distance between the signal point of the transmission bit 000000 and the reception signal point is obtained, and similarly, the distance 2 between the signal point of the transmission bit 000001, ..., 111111 and the reception signal point is obtained. Find the multiplier Z000001 (i), ..., Z111111 (i).
Next, the demodulation unit 1820 obtains the sum of X000000 (i), Y000000 (i), and Z (000000) K000000 (i) = X000000 (i) + Y000000 (i) + Z000000 (i), and similarly K000001 (i), ..., K111111 (i) is obtained. Similarly, the demodulation unit 1820 obtains K000000 (i + 1), K000001 (i + 1), ..., K111111 (i + 1) for the time i + 1.
Next, the demodulation unit 1820 compares the certainty of the received data between the time i and the time i + 1.
For example, the smallest value is searched from K000000 (i), K000001 (i), ..., K111111 (i). Let that value be F (i). Then search for the second smallest value. Let that value be S (i).
Similarly, the smallest value is searched from K000000 (i + 1), K000001 (i + 1), ..., K111111 (i + 1). Let that value be F (i + 1). Then search for the second smallest value. Let that value be S (i + 1).
Then, for example, R (i) = F (i) / S (i) and R (i + 1) = F (i + 1) / S (i + 1) are obtained.
When R (i + 1)> R (i), the demodulation unit 1820 determines that the reception quality is better at time i, and determines that the 6 bits giving F (i) are correct data. Then, as the 2 bits transmitted by the modulation signal A, the 2 bits obtained at the time i are used as the received data at the time i and the time i + 1. Regarding the modulated signals B and C, as the 2 bits transmitted at time i, the 2 bits obtained at time i are used as they are as the received data, whereas the 2 bits transmitted at time i + 1 are used. Judgment is made by utilizing the fact that the 2 bits transmitted by the modulated signal A at time i + 1 have already been determined.
For example, if the 2 bits transmitted by the modulation signal A are 00, then K000000 (i + 1), K000001 (i + 1), K000010 (i + 1), K000011 (i + 1), K000100 (i +) 1), K000101 (i + 1), K000110 (i + 1), K000111 (i + 1), K001000 (i + 1), K001001 (i + 1), K001010 (i + 1), K001011 (i + 1) ), K001100 (i + 1), K001101 (i + 1), K001110 (i + 1), K001111 (i + 1) By searching for the smallest value among the 16 points, time i + The 2 bits transmitted by the modulation signal B and the 2 bits transmitted by the modulation signal C are determined in 1.
Similarly, when the 2 bits transmitted by the modulation signal A are 01, 10, and 11, the 2 bits transmitted by the modulation signal B and the 2 bits transmitted by the modulation signal C are determined at time i + 1.
When R (i)> R (i + 1), the demodulation unit 1820 determines that the reception quality is better at time i + 1, and determines that the 6 bits giving F (i + 1) are correct data. .. Then, as the 2 bits transmitted by the modulation signal A, the 2 bits obtained at the time i + 1 are used as the received data at the time i and the time i + 1. Regarding the modulated signals B and C, as the 2 bits transmitted at time i + 1, the 2 bits obtained at time i + 1 are used as they are as received data, whereas the 2 bits transmitted at time i are used as they are. The bits are determined by utilizing the fact that the 2 bits transmitted by the modulated signal A at time i have already been determined.
For example, if the 2 bits transmitted by the modulation signal A are 00, then K000000 (i), K000001 (i), K000010 (i), K000011 (i), K000100 (i), K000101 (i), K000110 ( 16 points of i), K000111 (i), K001000 (i), K001001 (i), K001010 (i), K001011 (i), K001100 (i), K001101 (i), K001110 (i), K001111 (i) By searching for the one with the smallest value, the 2 bits transmitted by the modulation signal B and the 2 bits transmitted by the modulation signal C at time i are determined.
Similarly, when the 2 bits transmitted by the modulation signal A are 01, 10, and 11, the 2 bits transmitted by the modulation signal B and the 2 bits transmitted by the modulation signal C at time i are determined.
Next, the operation when the demodulation unit 1820 is configured as shown in FIG. 20 will be described.
As described above, the modulation signal A, B, C demodulation unit 1913 demodulates the data transmitted by the modulation signal A at time i and time i + 1 from the signal of the time with the better reception quality. Output as the received digital signal 524 of the modulated signal A. It also outputs the received digital signal 525-1 of the modulated signal B of either time i or time i + 1, and the received digital signal 1817-1 of the modulated signal C. Further, K000000 (i), ..., K111111 (i) are output as the first soft judgment value signal 1917, and K000000 (i + 1), ..., K111111 ( Output i + 1).
The modulation signals B and C demodulators 1919 are K000000 (i), ..., K111111 (i), which is the first soft judgment signal 1917, and K000000 (i + 1), which is the second soft judgment signal 1918. , ..., K111111 (i + 1) is input, and as described above, the modulated signal B and the modulated signal C are demoted based on the reception quality of time i and time i + 1, so that the received digital signal is received. Received the received digital signal 525-2 of the modulated signal B at a different time from the modulated signal B obtained from the signal 525-1. Received the modulated signal C at a different time from the modulated signal C obtained from the received digital signal 1817-1. Obtain the digital signal 1817-2.
Thus, according to the present embodiment, among the modulated signals A, B, and C transmitted from different antennas, the modulated signal A is formed by modulating the same data a plurality of times by changing the method of arranging the signal points. Modulated signals B and C are formed by sequentially modulating time-series data (that is, forming by applying normal modulation) without modulating the same data multiple times by changing the signal point arrangement. As a result, the error rate characteristics of the data series transmitted multiple times can be improved while maintaining the data transmission speed higher than when the spatiotemporal block code is used, and as a result, the error rate characteristics of all three systems are improved. You will be able to do it.
Actually, on the receiving side, the demodulation result of the modulated signal A obtained based on the received signal at the time with good reception quality is used as the received digital signal of the modulated signal A, and the modulated signal A at the time with good reception quality already determined is used. By using the received digital signal of the above to obtain the received digital signals of the modulated signals B and C received at the time of the poor reception quality from the received signal of the time of poor reception quality, the time of poor reception quality can be obtained. The error rate characteristics of the received modulated signals B and C can also be improved.
(2-1) Modification example 1 In the present embodiment, the case where the frame configuration transmitted by the transmission device 1700 is as shown in FIG. 15 has been described, but the frame configuration to be transmitted may be shown in FIG. The difference between the frame configuration of FIG. 16 and the frame configuration of FIG. 15 is that the difference in time for transmitting the signal S1 (i) in which the same data is modulated in the modulated signal A is reduced in the case of FIG. , In Fig. 16, it is a very large point.
As a result, the radio wave propagation environment becomes completely different between the time i and the time j. In consideration of this, in the case of FIG. 16, the signal point arrangement of the modulated signal A transmitted at time j is the same as the signal point arrangement of the modulated signal A transmitted at time i. This is because it is considered that the reception quality of time i and time j will be different to some extent due to the difference in the radio wave propagation environment even if the signal point arrangement of the modulated signal A is not changed.
As a result, the demodulation result of the modulated signal A obtained based on the received signal at the time with good reception quality is used as the received digital signal of the modulated signal A, and the received digital signal of the modulated signal A at the time with good reception quality already determined. If the received digital signals of the modulated signals B and C received at the time of the poor reception quality are obtained from the received signal of the time of the poor reception quality by using the above, the signal having the frame configuration of FIG. 15 is transmitted. Similarly, the error rate characteristics of the modulated signals B and C received at a time when the reception quality is poor can be improved.
This will be described in detail. At time i, the above equation (8) holds. Similarly, at time j, the relation of the following equation holds.<maths num="10"><img file="JP4445467B2_D0010.tif" /></maths>
In equation (10), h11 (j), h12 (j), h13 (j), h21 (j), h22 (j), h23 (j), h31 (j), h32 (j), h33 (j) are , In the receiving device 1800, for example, the radio wave propagation environment estimation symbols 801, 802, and 1503 of FIG. 16 are used for estimation. Here, since the radio wave propagation environment is different between the times i and j, h11 (i) h11 (j), h12 (i) h12 (j), h13 (i) h13 (j), h21 (i) h21 (j), h22 (i) h22 (j), h23 (i) h23 (j), h31 (i) h31 (j), h32 (i) h32 (j), h33 (i) h33 (j) holds. Therefore, the reception quality at time i and j will be completely different.
In consideration of the above, the signal point arrangement in the IQ plane of time i and time j will be described.
An example of the signal point arrangement in the IQ plane of the modulated signal A is shown in FIGS. 3A to 3C. When the frame configuration shown in FIG. 16 is adopted, the signal point arrangements at time i and j may both be FIG. 3A, or may be different as shown in FIG. 3A at time i and FIG. 3B at time j. This is different from the frame configuration in Fig. 15, because the radio wave propagation environment is different between time i and j, so time i and time j can be used without changing the signal point arrangement. This is because the reception quality will be different.
The decoding procedure will be described in detail below, but it can be considered in the same manner as the operation of the frame configuration of FIG. In other words, the operation of time i + 1 should be replaced with time j. <1> Detect for time i and obtain (S1 (i), S2 (i), S3 (i)). <2> Detect for time j and obtain (S1 (i), S2 (j), S3 (j)). <3> Compare the reception quality of time i and time j.
If the reception quality at time i is better, the data obtained by detection at time i (S1 (i), S2 (i), S3 (i)) is used as it is. Then, S1 (i) at time j is estimated from S1 (i) obtained by detection at time i, and the results are used to obtain S2 (j) and S3 (j).
If the reception quality at time j is better, the data obtained by detection at time j (S1 (i), S2 (j), S3 (j)) is used as it is. Then, S1 (i) at time i is estimated from S1 (i) obtained by detection at time j, and the results are used to obtain S2 (i) and S3 (i).
In the receiving device 1800, the demodulation unit 1820 performs such processing to obtain the received digital signal 524 of the modulated signal A, the received digital signal 525 of the modulated signal B, and the received digital signal 1817 of the modulated signal C.
Note that the detailed operation of the demodulation unit 1820 when the transmission signal of the frame configuration of FIG. 16 is received can be considered by replacing the operation of time i + 1 described above with time j for the frame configuration of FIG. Omit. However, in the above-mentioned processing at time i + 1 and time j, at time i + 1, the signal points (candidate signal points) obtained by using the radio wave propagation environment estimation symbols 101, 104, and 1401 in FIG. 15 are used. Whereas the accuracy of the data at time i + 1 was determined, at time j, the time was based on the signal points (candidate signal points) obtained using the radio wave propagation environment estimation symbols 801, 803, and 1503 in FIG. The difference is that the accuracy of the data in j is judged.
(2-2) Modification example 2 Here, an example is given in which the frame configuration transmitted by the transmission device 1700 is shown in FIG. 21 instead of FIG. The difference between the frame configuration of FIG. 21 and the frame configuration of FIG. 15 is that the difference in the time for transmitting the signals S1 (i) and S1 (i)'modulated with the same data in the modulated signal A is different in the case of FIG. Whereas it was set to "1", it was set to n in Fig. 21.
Here, h11 (i) h11 (i + n), h12 (i) h12 (i + n), h21 (i) h21 (i + n), h22 (i) h22 (i + n) If n is such that the relationship of is established, the same effect as when the signal having the frame configuration of FIG. 15 is transmitted can be obtained. That is, if the operation of time i + 1 is considered as the operation of time i + n, it can be carried out in the same manner.
(2-3) Modification 3 Here, it is proposed that the frame configuration transmitted by the transmission device 1700 is as shown in FIG. 22 instead of FIG. The frame configuration of FIG. 22 will be described. The modulated signal A transmits the same information at time i, i + 1, i + 2, and i + 3. Then, the signal point arrangement of S1 (i) is as shown in Fig. 3A, the signal point arrangement of S1 (i)'is as shown in Fig. 3B, and the signal point arrangement of S1 (i) "is as shown in Fig. 3C. The signal point arrangement of S1 (i) 'is different from that of Fig. 3A, Fig. 3B, and Fig. 3C. In this way, in the modulated signal A, the same information is transmitted at different signal point arrangements at time i, i + 1, i + 2, and i + 3. However, it is not always necessary to arrange different signal points. However, transmission with different signal point arrangements has the effect of increasing the possibility that the reception qualities of time i, i + 1, i + 2, and i + 3 will be different.
In the modulated signal B, the same information is transmitted at time i and i + 1, and the same information is transmitted at time i + 2 and i + 3. For example, at time i, S2 (i) is transmitted with the signal point arrangement shown in FIG. 3A. At time i + 1, S2 (i)'is transmitted with the signal point arrangement shown in Fig. 3B. At time i + 2, S2 (i + 2) is transmitted with the signal point arrangement shown in Fig. 3A. At time i + 3, S2 (i + 2)'is transmitted with the signal point arrangement shown in Fig. 3B.
The modulated signal C transmits different information at times i, i + 1, i + 2, and i + 3. The signal point arrangement of the modulated signal C is, for example, as shown in FIG. 3A.
As described above, the modulation signal A transmits the same information four times, and the modulation signal B transmits the same information twice. In this way, by changing the number of times that the same information is transmitted between the modulated signal A and the modulated signal B, the modulated signal A is demoted, then the modulated signal B is demoted, and then the modulated signal C is demoted. Such a demodulation operation becomes possible. As a result, the reception quality can be further improved as compared with the case of the embodiment, and the data transmission speed can be improved.
The signal having the frame configuration shown in FIG. 22 can be formed by, for example, the transmitter 2200 having the configuration shown in FIG. 23. In FIG. 23, which is shown by assigning the same reference numerals to the portions corresponding to those in FIG. 18, the transmission device 2200 differs from the transmission device 1700 in FIG. 18 in that it has a coding unit 2201.
The coding unit 2201 receives the transmission digital signal 313 and the frame configuration signal 324 of the modulation signal B as inputs, and encodes the transmission digital signal 313 according to the frame configuration of FIG. 22 to encode the transmission digital of the modulation method B. Obtains signal 2202 and outputs it.
The transmission signal of the frame configuration of FIG. 22 transmitted from the transmission device 2200 is received by the reception device 1800 shown in FIG. Then, when demodulating the transmission signal having the frame configuration of FIG. 22, the demodulation unit 1820 may be configured as shown in FIG. 24, for example.
The demodulation unit 1820 of FIG. 24 will be described.
The modulation signal A demodulator 2301 includes transmission path estimation signals 508, 518, 1808 for modulation signal A, transmission path estimation signals 510, 520, 1810 for modulation signal B, and transmission path estimation signals 1814, 1816, 1812 for modulation signal C. Received orthogonal baseband signals 506, 516, 1806 after despreading, frame configuration signal 522 as inputs, received digital signal 524 of modulation signal A, first soft judgment value signal 2303, second soft judgment value signal 2304, The third soft judgment value signal 2305 and the fourth soft judgment value signal 2306 are output.
The modulation signal B demodulator 2307 receives the first soft judgment value signal 2303, the second soft judgment value signal 2304, the third soft judgment value signal 2305, the fourth soft judgment value signal 2306, and the modulation signal A. The signal 524 and the frame configuration signal 522 are input, and the received digital signal 525 of the modulation signal B, the first soft judgment value signal 2309, the second soft judgment value signal 2310, the third soft judgment value signal 2311 and the fourth soft judgment value signal 2310. The soft judgment value signal 2312 is output.
The modulation signal C demodulator 2313 receives the first soft judgment value signal 2309, the second soft judgment value signal 2310, the third soft judgment value signal 2311, the fourth soft judgment value signal 2312, and the modulation signal A. The signal 524, the received digital signal 525 of the modulated signal B, and the frame configuration signal 522 are input, and the received digital signal 1817 of the modulated signal C is output.
Next, the operation of the demodulation unit 1820 when the transmission signal having the frame configuration of FIG. 22 is received will be described. The modulation signal A demodulator 2301 receives the modulation signal A by demodating the modulation signal A using the modulation signals at times i, i + 1, i + 2, and i + 3 in the frame configuration of FIG. 22. The soft judgment value signal at time i is used as the first soft judgment value signal 2303, and the soft judgment value signal at time i + 1 is used as the second soft judgment value signal 2304. Is output as the third soft judgment value signal 2305, and the soft judgment value signal at time i + 3 is output as the fourth soft judgment value signal 2306.
Next, the modulation signal B demodulator 2307 includes a first soft judgment value signal 2303, a second soft judgment value signal 2304, a third soft judgment value signal 2305, a fourth soft judgment value signal 2306, and a modulation signal A. The modulated signal of FIG. 22 is taken from the received digital signal 524 of FIG. 22 and the result of the received digital signal 524 of the modulated signal A is used, and the first soft judgment value signal 2303 and the second soft judgment value signal 2304 are used. Demote the information S2 (i), S2 (i)'transmitted at time i and i + 1 of B. Further, using the result of the received digital signal 524 of the modulation signal A, and using the third soft judgment value signal 2305 and the fourth soft judgment value signal 2306, the time i + 2 of the modulation signal B in FIG. 22 Demodulate the information S2 (i + 2), S2 (i + 2)'transmitted by i + 3. Then, these demodulation results are output as the received digital signal 525 of the modulation signal B.
The modulation signal C demodulator 2313 receives the first soft judgment value signal 2309, the second soft judgment value signal 2310, the third soft judgment value signal 2311, the fourth soft judgment value signal 2312, and the modulation signal A. The time is taken by using the signal 524 and the received digital signal 525 of the modulated signal B as inputs, using the received digital signal 524 of the modulated signal A and the received digital signal 525 of the modulated signal B, and using the first soft determination value signal 2309. Demote the information S3 (i) of the modulation signal C transmitted by i. Similarly, the information transmitted by the modulated signal C at time i + 1 using the received digital signal 524 of the modulated signal A and the received digital signal 525 of the modulated signal B and using the second soft determination value signal 2310. Demodulate S3 (i + 1). Similarly, the information transmitted by the modulated signal C at time i + 2 using the received digital signal 524 of the modulated signal A and the received digital signal 525 of the modulated signal B and using the third soft determination value signal 2311. Demodulate S3 (i + 2). Similarly, the information transmitted by the modulated signal C at time i + 3 using the received digital signal 524 of the modulated signal A and the received digital signal 525 of the modulated signal B and using the fourth soft determination value signal 2312. Demodulate S3 (i + 3).
Thus, the modulation signal A and the modulation signal B transmit the modulation signal of the same data a plurality of times, and the number of transmissions of the same data of the modulation signal A is made larger than the number of transmissions of the same data of the modulation signal B. On the side, first the modulation signal A is demoted, then the modulation signal B is demolished based on the demodulation result of the modulation signal A, and then the modulation signal C is demolished based on the modulation result of the modulation signal A and the modulation signal B. By performing demodulation, it is possible to obtain demodulated data having good error rate characteristics in all of the modulated signals A, B, and C. Further, the error rate characteristic can be improved while maintaining the data transmission speed higher than that when the spatiotemporal block code is used.
(2-4) Modification example 4 Here, it is proposed that the frame configuration transmitted by the transmission device 1700 is as shown in FIG. In FIG. 25, the parts corresponding to FIG. 22 are designated by the same reference numerals as those in FIG. 22. The frame configuration of FIG. 25 differs from the frame configuration of FIG. 22 in that the modulation symbols of the same data are transmitted at intervals of 1 time in the frame configuration of FIG. 22, whereas the modulation symbols of the same data are modulated in the frame configuration of FIG. This is the point at which symbols are transmitted at time n intervals.
Here, h11 (i) h11 (i + n) h11 (i + 2n) h11 (i + 3n), h12 (i) h12 (i + n) h12 (i + 2n) h12 (i) + 3n), h13 (i) h13 (i + n) h13 (i + 2n) h13 (i + 3n), h21 (i) h21 (i + n) h21 (i + 2n) h21 (i + 3n), h22 (i) h22 (i + n) h22 (i + 2n) h22 (i + 3n), h23 (i) h23 (i + n) h23 (i + 2n) h23 (i + 3n), h31 (i) h31 (i + n) h31 (i + 2n) h31 (i + 3n), h32 (i) h32 (i + n) h32 (i + If the relationship of 2n) h32 (i + 3n), h33 (i) h33 (i + n) h33 (i + 2n) h33 (i + 3n) is established, then in Fig. 22 It can be carried out in the same manner as when a signal having a frame configuration is transmitted. That is, the operation of time i + 1 in FIG. 22 is the operation of time i + n in FIG. 25, the operation of time i + 2 in FIG. 22 is the operation of time i + 2n in FIG. If the operation is considered as the operation of the time i + 3n in FIG. 25, it can be carried out in the same manner as the description of the frame configuration in FIG. 22.
(2-5) Modification example 5 Here, it is proposed that the frame configuration transmitted by the transmission device 1700 is as shown in FIG. In FIG. 26, the parts corresponding to FIG. 22 are designated by the same reference numerals as those in FIG. 22. The frame configuration of FIG. 25 differs from the frame configuration of FIG. 22 in that the modulation symbols of the same data are transmitted at intervals of 1 time in the frame configuration of FIG. 22, whereas the modulation symbols of the same data are modulated in the frame configuration of FIG. The point at which the symbol is transmitted at time i, j, k, m.
Here, h11 (i) h11 (j) h11 (k) h11 (m), h12 (i) h12 (j) h12 (k) h12 (m), h13 (i) h13 (j) ) h13 (k) h13 (m), h21 (i) h21 (j) h21 (k) h21 (m), h22 (i) h22 (j) h22 (k) h22 (m) ), H23 (i) h23 (j) h23 (k) h23 (m), h31 (i) h31 (j) h31 (k) h31 (m), h32 (i) h32 (j) ) h32 (k) h32 (m), h33 (i) h33 (j) h33 (k) h33 (m).
The operation of time i + 1 in FIG. 22 is the operation of time j in FIG. 26, the operation of time i + 2 in FIG. 22 is the operation of time k in FIG. Considering the operation of m, it can be carried out in the same manner as the description of the frame configuration in FIG. However, in the frame configuration of FIG. 26, a symbol for estimating the radio wave propagation environment at time j is required separately from the radio wave propagation environment estimation symbols 2101, 2106, and 2111. Similarly, a symbol for estimating the radio wave propagation environment at time k is required separately from the radio wave propagation environment estimation symbols 2101, 2106, and 2111. Then, a symbol for estimating the radio wave propagation environment at time m is required separately from the radio wave propagation environment estimation symbols 2101, 2106, and 2111.
(2-6) Modification 6 In this embodiment, the modulation method of the modulation signals A and B has been described as QPSK. In the following, a method of setting a modulation method suitable for forming the modulation signals A and B will be described.
For example, when the modulation method of the modulation signals A and B is 16QAM, the density of the signal points in the IQ plane becomes high, and it is difficult to give a large change in the Euclidean distance even if the phase rotation is given, so that the reception quality Can't hope for a big improvement in.
As a method of solving this problem, that is, giving phase rotation and changing the Euclidean distance, the modulation method of the modulation signal A is BPSK or QPSK, and the modulation method of the modulation signal B is 8PSK, 16QAM, 64QAM, 128QAM. , 256QAM can be considered. In this way, there is an advantage that the signal points are regularly arranged when the signal is received. Then, it is more preferable to set the transmission power of the modulation signal A and the transmission power of the modulation signal B to appropriate values.
For example, when the modulation signal A is QPSK and the modulation signal B is 16QAM, the transmission power of the modulation signal A: the transmission power of the modulation signal B = 2:10 may be set.
When the modulation signal A is QPSK and the modulation signal B is 64QAM, it is advisable to set the transmission power of the modulation signal A: the transmission power of the modulation signal B = 2:42.
When the modulation signal A is BPSK and the modulation signal B is 16QAM, it is preferable to set the transmission power of the modulation signal A: the transmission power of the modulation signal B = 1:10.
When the modulation signal A is BPSK and the modulation signal B is 64QAM, it is preferable to set the transmission power of the modulation signal A: the transmission power of the modulation signal B = 1: 42.
(2-7) Modification 7 The configuration of the transmitter is not limited to the configurations shown in FIGS. 18 and 23. Further, the configuration of the receiving device is not limited to the configuration shown in FIG. 19, and the configuration of the demodulation unit is not limited to the configuration shown in FIGS. 20 and 24.
Further, in the present embodiment, the frame configuration for transmitting three types of modulated signals A, B, and C has been described, but the same can be performed when transmitting n (n 4) different modulated signals. .. In short, if there is a modulated signal that transmits data a plurality of times among the n types of modulated signals, the same effect as that of the present embodiment can be obtained.
The frame configuration is not limited to that shown in FIGS. 15, 16, 21, 26, 25, and 26, and the same data can be obtained by transmitting the same data multiple times by changing the signal point arrangement method. The effect can be obtained. Further, in the present embodiment, the frame configuration in which the same data is transmitted twice in the modulation signal A and the frame configuration in which the same data is transmitted four times are described in the frame configuration in which the same data is transmitted twice in the modulation signal B. The same can be applied to a frame configuration in which the same data is transmitted n (n 4) times for each of the modulated signals A and B. Here, as the number of n is increased, the apparent data transmission speed that can be transmitted by the modulated signals A and B decreases, but the error rate characteristics when the modulated signals A, B and C are demodulated are improved. If n is set as much as the radio wave propagation environment is worse, the actual data transmission speed can be increased.
Further, in the present embodiment, the modulation signal A, the modulation signal B, and the modulation signal C are coded in the time axis direction. That is, in the example of the present embodiment, in the modulated signal A, the modulated signals of the same data are transmitted at different times. However, the coding of this embodiment can be performed in the frequency axis direction, particularly when a multi-carrier method such as the OFDM method is used. For example, the modulation signal A may have a plurality of symbols of the same data arranged on different carriers.
Further, in the present embodiment, by improving the reception quality of the modulation signal A, the reception quality of the modulation signal B and the modulation signal C is also improved. Further, by improving the reception quality of the modulated signal B, the reception quality of the modulated signal C is also improved. In addition to the present embodiment, if the modulation signal A and the modulation signal B are coded such as a block code, a convolutional code such as a bitabi code or a turbo code, and an LDPC code, the received signals A and B Since the reception quality of the modulation signal C can be further improved, the reception quality of the modulated signal C can also be further improved.
However, the block code, the convolutional code such as the Viterbi code and the turbo code, and the error correction code such as the LDPC code are applied not only to the modulation signals A and B but also to all the modulation signals A, B, and C. You may. In this case, after decoding the modulated signal A, the modulated signals B and C are decoded.
(3) Embodiment 3 In the present embodiment, a case where the first and second embodiments and the OFDM method are combined will be described.
FIG. 27 shows a configuration example of the transmission device according to the present embodiment. The coding unit 2602 inputs the transmission digital signal 2601 of the modulation signal A and the frame configuration signal 2624, and outputs the encoded transmission digital signal 2603. The modulation unit 2625 takes the encoded transmission digital signal 2603 and the frame configuration signal 2624 as inputs, and outputs the transmission orthogonal baseband signal 2626 according to the frame configuration signal 2624. The serial-parallel conversion unit 2604 inputs the transmission orthogonal baseband signal 2626 and the frame configuration signal 2624, and outputs the parallel signal 2605. The inverse Fourier transform unit 2606 takes the parallel signal 2605 as an input and outputs the signal 2607 after the inverse Fourier transform. The radio unit 2608 converts the signal 2607 after the inverse Fourier transform from the baseband frequency to the radio frequency, and outputs the converted modulated signal 2609. The power amplifier 2610 amplifies the power of the modulated signal 2609 and outputs the amplified modulated signal 2611. The modulated signal 2611 is output as a radio wave from the antenna 2612.
The modulation unit 2627 takes the transmission digital signal 2613 of the modulation signal B and the frame configuration signal 2624 as inputs, and outputs the transmission orthogonal baseband signal 2628. The serial-parallel conversion unit 2614 takes the transmission orthogonal baseband signal 2628 as an input and outputs the parallel signal 2615. The inverse Fourier transform unit 2616 takes the parallel signal 2615 as an input and outputs the signal 2617 after the inverse Fourier transform. The radio unit 2618 converts the signal 2617 after the inverse Fourier transform from the baseband frequency to the radio frequency, and outputs the converted modulated signal 2619. The power amplifier 2620 amplifies the power of the modulated signal 2619 and outputs the amplified modulated signal 2621. The modulated signal 2621 is output as a radio wave from the antenna 2622.
FIG. 28 shows a configuration example of the receiving device according to the present embodiment. The radio unit 2703 inputs the received signal 2702 received by the antenna 2701 and outputs the received orthogonal baseband signal 2704. The Fourier transform unit 2705 takes the received orthogonal baseband signal 2704 as an input and outputs the signal 2706 after the Fourier transform.
The modulation signal A transmission line estimation unit 2707 takes the Fourier transformed signal 2706 as an input and outputs the transmission line estimation signal group 2708 of the modulation signal A. The modulated signal B transmission line estimation unit 2709 takes the Fourier transformed signal 2706 as an input and outputs the transmission line estimation signal group 2710 of the modulated signal B.
The radio unit 2713 receives the reception signal 2712 received by the antenna 2711 as an input, and outputs a reception orthogonal baseband signal 2714. The Fourier transform unit 2715 takes the received orthogonal baseband signal 2714 as an input and outputs the signal 2716 after the Fourier transform.
The modulation signal A transmission line estimation unit 2717 takes the Fourier transformed signal 2716 as an input and outputs the transmission line estimation signal group 2718 of the modulation signal A. The modulation signal B transmission line estimation unit 2719 takes the Fourier transformed signal 2716 as an input and outputs the transmission line estimation signal group 2720 of the modulation signal B.
The demodulator 2721 receives the transmission path estimation signals 2708 and 2718 of the modulation signal A, the transmission path estimation signals 2710 and 2720 of the modulation signal B, and the signals 2706 and 2716 after Fourier conversion as inputs, and receives the digital signal of the modulation signal A. 2722, Received modulation signal B Outputs digital signal 2723.
FIGS. 29A and 29B show an example of a frame configuration according to the present embodiment, in which 2801 is a radio wave propagation environment estimation symbol and 2802 is a data symbol, which are coded in the time axis direction. The modulated signal A is encoded by carrier 1 over time i and i + 1. The modulated signal B is encoded by carrier 1 over time i and i + 1.
The modulated signal A transmits S1 (i) at time i and S1 (i)'at time i + 1 in carrier 1. As described above, S1 (i) and S1 (i)'are modulation symbols formed by changing the signal point arrangement of the same data.
The modulated signal B transmits S2 (i) at time i and S2 (i + 1) at time i + 1 in carrier 1. S2 (i) and S2 (i + 1) are modulation symbols formed from different data.
30A and 30B show another frame configuration example in the present embodiment, and the parts corresponding to those in FIGS. 29A and 29B are designated by the same reference numerals. In the case of FIGS. 30A and 30B, the modulation symbol is encoded in the frequency axis direction. The modulated signal A is encoded over carrier 1 and carrier 2 at time i. The modulated signal B is encoded over carrier 1 and carrier 2 at time i.
At time i, the modulated signal A transmits S1 (i) at carrier 1 and S1 (i)'at carrier 2. At time i, the modulated signal B transmits S2 (i-1) on the carrier 1 and S2 (i-2) on the carrier 2. Here, S2 (i-1) and S2 (i-2) are modulation symbols formed from different data.
31A and 31B show another frame configuration example in the present embodiment, and the corresponding parts of FIGS. 29A and 29B are designated by the same reference numerals. In the case of FIGS. 31A and 31B, the modulation symbols are encoded in the time axis direction. The modulated signal A is coded at time i and time i + n in carrier 1. The modulated signal B is coded at time i and time i + n in carrier 1.
The modulated signal A transmits S1 (i) at time i and S1 (i)'at time i + n in carrier 1. The modulated signal B transmits S2 (i) at time i and S2 (i + 1) at time i + n in carrier 1.
32A and 32B show another frame configuration example in the present embodiment, and the parts corresponding to those in FIGS. 29A and 29B are designated by the same reference numerals. In the case of FIGS. 32A and 32B, the modulation symbols are encoded in the frequency axis direction. The modulated signal A is encoded by carrier 1 and carrier 1 + n at time i. The modulated signal B is encoded by carrier 1 and carrier 1 + n at time i.
At time i, the modulated signal A transmits S1 (i) at carrier 1 and S1 (i)'at carrier 1 + n. The modulated signal B transmits S2 (i-1) at carrier 1 and S2 (i-2) at carrier 1 + n at time i.
33A and 33B show another frame configuration example in the present embodiment, and the parts corresponding to those in FIGS. 29A and 29B are designated by the same reference numerals. In the case of FIGS. 33A and 33B, the modulation symbols are encoded in the time axis direction. The modulated signal A is coded at time i and time j in carrier 1. The modulated signal B is coded at time i and time j in carrier 1.
The modulated signal A transmits S1 (i) at time i and S1 (i)'at time j at carrier 1. The modulated signal B transmits S2 (i-1) at time i and S2 (i + n) at time j in carrier 1.
34A and 34B show another frame configuration example in the present embodiment, and the parts corresponding to those in FIGS. 29A and 29B are designated by the same reference numerals. In the case of FIGS. 34A and 34B, the modulation symbol is encoded in the frequency axis direction. The modulated signal A is coded by carrier 1 and carrier j at time i. The modulated signal B is coded by carrier 1 and carrier j at time i.
At time i, the modulated signal A transmits S1 (i) at carrier 1 and S1 (i)'at carrier j. At time i, the modulated signal B transmits S2 (i-1) at carrier 1 and S2 (ij) at carrier j.
35A and 35B show another frame configuration example in the present embodiment, and the corresponding parts of FIGS. 29A and 29B are designated by the same reference numerals. The modulated signal A is encoded at time i, time i + 1, and time i + 2 in carrier 1. The modulated signal B is encoded at time i, time i + 1, and time i + 2 in carrier 1.
The modulated signal A transmits S1 (i) at time i, S1 (i)'at time i + 1, and S (i) at time i + 2 in carrier 1. "S1 (i), S1 (i)', S (i)" is formed by changing the signal point arrangement of the same data. The modulated signal B transmits S2 (i) at time i, S2 (i + 1) at time i + 1, and S2 (i + 2) at time i + 2 in carrier 1. Here, S2 (i), S2 (i + 1), and S2 (i + 2) are obtained by modulating different data.
36A and 36B show another frame configuration example in the present embodiment, and the parts corresponding to those in FIGS. 29A and 29B are designated by the same reference numerals. The modulated signal A is encoded by carrier 1, carrier 2, and carrier 3 at time i. The modulated signal B is encoded by carrier 1, carrier 2, and carrier 3 at time i.
At time i, the modulated signal A transmits S1 (i) at carrier 1, S1 (i)'is transmitted at carrier 2, and S1 (i) is transmitted at carrier 2. Modulated signal B is time. In i, carrier 1 transmits S2 (i-1), carrier 2 transmits S2 (i-2), and carrier 3 transmits S2 (i-3).
37A and 37B show another frame configuration example in the present embodiment, and the parts corresponding to those in FIGS. 29A and 29B are designated by the same reference numerals. The modulated signal A transmits the same data at time i, time j, and time k in carrier 1 by symbols S1 (i), S1 (i)', S1 (i) with different signal point arrangements (same signal). The modulation signal B may be point-arranged). In carrier 1, different data at time i, time j, and time k are transmitted by symbols S2 (i), S2 (j), and S2 (k).
38A and 38B show another frame configuration example in the present embodiment, and the parts corresponding to those in FIGS. 29A and 29B are designated by the same reference numerals. The modulated signal A transmits the same data at carrier i, carrier j, and carrier k at time i by symbols S1 (i), S1 (i)', S1 (i) with different signal point arrangements (same signal). The point arrangement may be used). At the time point i, the modulated signal B transmits different data for the carrier i, the carrier j, and the carrier k by the symbols S2 (i), S2 (j), and S2 (k).
39A to 39C show another frame configuration example in the present embodiment, and the corresponding parts of FIGS. 29A and 29B are designated by the same reference numerals. The modulated signal A transmits the same data at time i and time i + 1 on the carrier 1 by symbols S1 (i) and S1 (i)'with different signal point arrangements. The modulated signal B transmits different data at time i and time i + 1 in carrier 1 by symbols S2 (i) and S2 (i + 1). The modulated signal C transmits different data at time i and time i + 1 in carrier 1 by symbols S3 (i) and S3 (i + 1).
40A to 40C show another frame configuration example in the present embodiment, and the corresponding parts of FIGS. 29A and 29B are designated by the same reference numerals. At time i, the modulated signal A transmits the same data for carriers 1 and 2 by symbols S1 (i) and S1 (i)'with different signal point arrangements. The modulated signal B transmits different data for the carrier 1 and the carrier 2 by the symbols S2 (1) and S2 (2) at the time i. The modulated signal C transmits different data for the carrier 1 and the carrier 2 by the symbols S3 (1) and S3 (2) at the time i.
41A to 41C show another frame configuration example in the present embodiment, and the corresponding parts of FIGS. 29A and 29B are designated by the same reference numerals. The modulated signal A transmits the same data at time i and time j at time i and time j by symbols S1 (i) and S1 (i)'with different signal point arrangements (the same signal point arrangement may be used). The modulated signal B transmits different data at time i and time j on the carrier 1 by the symbols S2 (i) and S2 (j). The modulated signal C transmits different data at time i and time j on the carrier 1 by the symbols S3 (i) and S3 (j).
42A to 42C show another frame configuration example in the present embodiment, and the corresponding parts of FIGS. 29A and 29B are designated by the same reference numerals. At time i, the modulated signal A transmits the same data for carriers i and j by symbols S1 (i) and S1 (i)'with different signal point arrangements. The modulated signal B transmits different data for the carrier i and the carrier j at time i by the symbols S2 (i) and S2 (j). The modulated signal C transmits different data for the carrier i and the carrier j at time i by the symbols S3 (i) and S3 (j).
FIGS. 43A to 43C show another frame configuration example in the present embodiment, and the corresponding parts of FIGS. 29A and 29B are designated by the same reference numerals. The modulated signal A is the same data at time i, time i + 1, i + 2, and i + 3 in carrier 1, and symbols S1 (i), S1 (i)', S1 (i) with different signal point arrangements. , S1 (i) "'Send by. The modulated signal B transmits the same data at time i and time i + 1 by the symbols S2 (i) and S2 (i)'with different signal point arrangements in carrier 1, and at time i + 2 and time i + 3. The same data is transmitted by the symbols S2 (i + 2) and S2 (i + 2)'with different signal point arrangements. The modulated signal C represents different data at time i, time i + 1, time i + 2, and time i + 3 in carrier 1, symbols S3 (i), S3 (i + 1), S3 (i + 2), Send by S3 (i + 3).
FIGS. 44A to 44C show another frame configuration example in the present embodiment, and the parts corresponding to those in FIGS. 29A and 29B are designated by the same reference numerals. At time i, the modulated signal A has the same data for carriers 1, carrier 2, carrier 3, and carrier 4, and symbols S1 (i), S1 (i)', S1 (i) , and S1 (i) with different signal point arrangements. ) Send by "'. At time i, the modulated signal B transmits the same data on carriers 1 and 2 by symbols S2 (1) and S2 (1)'with different signal point arrangements, and transmits the same data on carriers 3 and 4 at signal point arrangements. Sent by different symbols S2 (3), S2 (3)'. The modulated signal C transmits different data for the carriers 1, carrier 2, carrier 3, and carrier 4 at time i by the symbols S3 (1), S3 (2), S3 (3), and S3 (4).
45A to 45C show another frame configuration example in the present embodiment, and the corresponding parts of FIGS. 29A and 29B are designated by the same reference numerals. The modulated signal A is the same data at time i, time j, time k, and time m in carrier 1, and symbols S1 (i), S1 (i)', S1 (i) , S1 (i) with different signal point arrangements. ) Send by "'. In carrier 1, the modulated signal B transmits the same data at time i and time j by symbols S2 (i) and S2 (i)'with different signal point arrangements, and transmits the same data at time k and time m at signal point arrangements. Sent by different symbols S2 (k), S2 (k)'. The modulated signal C transmits different data at time i, time j, time k, and time m on the carrier 1 by the symbols S3 (i), S3 (j), S3 (k), and S3 (m).
FIGS. 46A to 46C show another frame configuration example in the present embodiment, and the corresponding parts of FIGS. 29A and 29B are designated by the same reference numerals. The modulated signal A has the same data at carrier 1, carrier j, carrier k, and carrier m at time i, and symbols S1 (i), S1 (i)', S1 (i) , S1 (i) with different signal point arrangements. ) Send by "'. The modulated signal B transmits the same data at the carrier i and the carrier j by the symbols S2 (i) and S2 (i)'with different signal point arrangements at the time i, and transmits the same data at the carrier k and the carrier m at the signal point arrangement. Sent by different symbols S2 (k), S2 (k)'. The modulated signal C transmits different data for the carrier i, the carrier j, the carrier k, and the carrier m at the time i by the symbols S3 (i), S3 (j), S3 (k), and S3 (m).
Next, Fig. 2A, Fig. 2B, Fig. 3A to Fig. 3C, Fig. 5, Fig. 14, Fig. 25, Fig. 27, Fig. 28, Fig. 29A, Fig. 29B, Fig. 30A, Fig. 30B, Fig. 31A, Fig. 31B, Fig. 32A. , Fig. 32B, Fig. 33A, Fig. 33B, Fig. 34A, Fig. 34B, Fig. 35A, Fig. 35B, Fig. 36A, Fig. 36B, Fig. 37A, Fig. 37B, Fig. 38A, Fig. 38B, Fig. 39A to Fig. 39C, Fig. 40A to Fig. The operation of this embodiment will be described in detail with reference to 40C, FIGS. 41A to 41C, 42A to 42C, 43A to 43C, 44A to 44C, 45A to 45C, and 46A to 46C. To do.
29A and 29B show an example of the frame configuration of the modulation signal A and the modulation signal B transmitted by the transmission device 2600 of FIG. 27. The frame configuration of the modulation signal transmitted from the modulation signal A transmission unit in FIG. 27 is the modulation signal A frame configuration of FIG. 29A. Further, the frame configuration of the modulation signal transmitted from the modulation signal B transmission unit in FIG. 27 is the modulation signal B frame configuration of FIG. 29B.
The feature of the frame configuration of FIGS. 29A and 29B is that in the modulated signal A, the same data at time i and time time i + 1 is input by the symbols S1 (i) and S1 (i)'with different signal point arrangements in the carrier 1. On the other hand, in the modulated signal B, the carrier 1 transmits different data at time i and time i + 1 by the symbols S2 (i) and S2 (i + 1).
Figures 3A to 3C show the signal point arrangement in the IQ plane of S1 (i) and S1 (i)'. The modulation method is QPSK. For example, in FIG. 29A, it is assumed that (0,0) is transmitted as information of S1 (i) at time i. At this time, the signal points are as shown in FIG. 3A. Then, at time i + 1, (0,0) is transmitted as information, for example, as shown in FIG. 3B. The same applies to (0,1), (1,0), and (1,1). However, the signal point arrangement at time i + 1 is not limited to FIG. 3B, and the signal point arrangement as shown in FIG. 3C may be used.
By doing so, focusing on carrier 1, in the receiver 2700, the signal point arrangement of the modulated signal changes between time i and time i + 1, so the modulated signal A, at time i and time i + 1. The accuracy of demodulation of the modulated signal B will be different. Therefore, the accuracy of demodulation of the modulated signal B can be improved by demodulating the modulated signal A at a time with good demodulation accuracy and then using the result to demodulate the modulated signal B. That is, the demodulation accuracy of both the modulated signals A and B can be improved.
Here, the operation of the transmitting device 2600 when the transmitting device 2600 forms the modulated signals A and B having the frame configurations of FIGS. 29A and 29B will be described.
The frame configuration signal generation unit 2623 outputs the frame configuration information of FIGS. 29A and 29B as the frame configuration signal 2624. The coding unit 2602 receives the transmission digital signal 2601 and the frame configuration signal 2624 as inputs, encodes the transmission digital signal 2601 as in the frame configuration of the modulation signal A of FIG. 29A, and outputs the encoded digital signal 2603.
The modulation unit 2625 takes the encoded digital signal 2603 and the frame configuration signal 2624 as inputs, and outputs a transmission orthogonal baseband signal 2626 according to the frame configuration of the modulation signal A of FIG. 29A. The modulation unit 2625 may have a configuration as shown in FIG. 5, for example.
In FIG. 5, the mapping unit X402 maps the signal points as shown in FIG. 3A. The mapping unit Y404 maps the signal points as shown in FIG. 3B or FIG. 3C.
For example, when focusing on carrier 1 in the frame configurations of FIGS. 29A and 29B, when the frame configuration signal 2624 indicates the symbols of the modulation signal A, the carrier 1, and the time i, the mapping unit X402 is input digital. Mapping is applied to the signal, and the first mapped transmission orthogonal baseband signal 403 is output.
On the other hand, when the frame configuration signal 2624 indicates the symbols of the modulation signal A, the carrier 1, and the time i + 1, the mapping unit Y404 performs mapping on the input digital signal and performs a second mapping. The transmitted orthogonal baseband signal 405 is output.
The signal selection unit 407 includes a first mapped transmission orthogonal baseband signal 403, a second mapped transmission orthogonal baseband signal 405, and a frame configuration signal.<u style="single">324</u>Is used as an input, and the frame configuration signal<u style="single">324</u>Selects the signal indicated by and outputs the selected transmission orthogonal baseband signal 305.
Here, the frame configuration of FIGS. 29A and 29B, that is, the case of coding at time i and time i + 1 has been described as an example, but as shown in FIGS. 31A and 31B, the time i and i + n are used. The same can be performed when it is encoded. That is, in the above description, if the operation of time i + 1 is considered as the operation of time i + n, it can be carried out in the same manner. Further, although the description has been focused on the carrier 1, carriers other than the carrier 1 can be similarly encoded by applying the same coding.
Next, the configuration of the receiving device will be described. FIG. 28 shows the configuration of the receiving device according to the present embodiment. It is assumed that the receiving antenna 2701 of FIG. 28 corresponds to the antenna 109 of FIG. 2B, and the receiving antenna 2711 corresponds to the antenna 110 of FIG. 2B.
In the following, the operation of carrier 1 will be described as an example. The modulation signal A transmission line estimation unit 2707 of FIG. 28 obtains the channel variation h11 (t) of the carrier 1 by using the modulation signal A of FIG. 29A, the carrier 1, and the radio wave propagation environment estimation symbol 2801 at time i. However, t is time. Similarly, the modulation signal B transmission line estimation unit 2709 obtains the channel variation h12 (t) of the carrier 1 by using the modulation signal B of FIG. 29B, the carrier 1, and the radio wave propagation environment estimation symbol 2801 at time i. The modulation signal A transmission line estimation unit 2717 obtains the channel variation h21 (t) of the carrier 1 by using the modulation signal A of FIG. 29A, the carrier 1, and the radio wave propagation environment estimation symbol 2801 at time i. However, t is time. Similarly, the modulation signal B transmission line estimation unit 2719 obtains the channel variation h22 (t) of the carrier 1 by using the modulation signal B of FIG. 29B, the carrier 1, and the radio wave propagation environment estimation symbol 2801 at time i.
Then, at time i, if the signal of the carrier 1 received by the receiving antenna 2701 is R1 (i) and the signal of the carrier 1 received by the receiving antenna 2711 is R2 (i), the equation (1) is established. Similarly, at time i + 1, Eq. (2) holds. S1 (i) and S2 (i) can be obtained from the relationship of Eq. (1), and S1 (i)'and S2 (i + 1) can be obtained from the relationship of Eq. (2).
Also, h11 (i) h11 (i + 1), h12 (i) h12 (i + 1), h21 (i) h21 (i + 1), h22 (i) h22 (i + 1) are established. To do. At this time, the matrices of Eqs. (1) and (2) are almost equal, but the vectors of (S1 (i), S2 (i)) and (S1 (i)', S2 (i + 1) ) Is different, so the certainty of the obtained data is different.
In the present embodiment, this characteristic is used to improve the quality of received data. The specific demodulation (decoding) procedure of the receiving device 2700 is as follows. <1> Detect for time i and obtain (S1 (i), S2 (i)). <2> Detects time i + 1 and obtains (S1 (i)', S2 (i + 1)). <3> Compare the reception quality of time i and time i + 1.
If the reception quality at time i is better, the data (S1 (i), S2 (i)) obtained by the detection at time i is used as it is. Then, the data of S2 (i + 1) is obtained by estimating S1 (i)'at time i + 1 from S1 (i) obtained by the detection at time i and using the result.
On the other hand, when the reception quality at time i + 1 is better, the data obtained by the detection at time i + 1 (S1 (i)', S2 (i + 1)) is used as it is. Then, the data of S2 (i) is obtained by estimating S1 (i) of time i from S1 (i)'obtained by the detection of time i + 1 and using the result.
In the receiving device 2700, the demodulation unit 2721 performs such demodulation processing to obtain the received digital signal 2722 of the modulated signal A and the received digital signal 2723 of the modulated signal B.
The detailed configuration of the demodulation unit 2721 in FIG. 28 is as shown in FIG. 8, and the operation thereof will be described below.
In FIG. 8, signal 508 is signaled to 2708 of FIG. 28, signal 510 is signaled to 2710 of FIG. 28, signal 506 is signaled to 2706 of FIG. 28, signal 518 is signaled to 2718 of FIG. 28, and signal 520 is signaled to 2720 of FIG. 28. 516 corresponds to 2716 in Fig. 28.
Here, in the transmission device 2600 of FIG. 27, a case where a signal is transmitted by QPSK modulation for both the modulation signal A and the modulation signal B in the frame configuration of FIGS. 29A and 29B will be described as an example. However, it is an explanation about carrier 1.
A total of 4 bits, 2 bits for the modulated signal A and 2 bits for the modulated signal B, can be transmitted. That is, 0000, 0001, ..., 1111 can be transmitted. However, the upper 2 bits are the 2 bits transmitted by the modulation signal A, and the lower 2 bits are the 2 bits transmitted by the modulation signal B.
Here, the operation of the demodulation unit 2721 in FIG. 28 will be described.
The demodulator 2721 uses the carrier 1 component of the transmission line estimation signal group 2708 of the modulation signal A and the carrier 1 component of the transmission line estimation signal group 2710 of the modulation signal B at carrier 1 and time i, 0000,0001. Find the signal points in the IQ plane of the 16 signal points of, ..., 1111. The state at that time corresponds to the 16 signal points 1302 in FIG.
Then, the reception state in the IQ plane can be obtained from the component of the carrier 1 of the signal 2706 after the Fourier transform. The state at that time corresponds to the signal point 1301 in FIG.
Next, for example, the square value of the distance in the IQ plane of all the signal points and the signal points 1301 shown in 1302 in FIG. 14 is calculated. That is, the square value X0000 (i) of the distance between the signal point 1302 of the transmission bit 0000 and the signal point 1301 is obtained, and similarly, the distance between the signal point 1302 and the signal point 1301 of the transmission bits 0001, ..., 1111 is obtained. The squared value of X0001 (i), ..., X1111 (i) is obtained.
Similarly, at carrier 1 and time i in FIGS. 29A and 29B, the component of carrier 1 of the transmission line estimation signal group 2718 of the modulation signal A and the component of carrier 1 of the transmission line estimation signal group 2720 of the modulation signal B are used. , 0000, 0001, ···, 1111 16 signal points in the IQ plane are obtained. The state at that time corresponds to the 16 signal points of 1302 in FIG.
Then, the reception state in the IQ plane can be obtained from the component of carrier 1 of the signal 2716 after Fourier transform. The state at that time corresponds to the signal point 1301 in FIG.
Next, for example, the square value of the distance in the IQ plane of all the signal points and the signal points 1301 shown in 1302 in FIG. 14 is calculated. That is, the square value Y0000 (i) of the distance between the signal point 1302 of the transmission bit 0000 and the signal point 1301 is obtained, and similarly, the distance between the signal point 1302 and the signal point 1301 of the transmission bits 0001, ..., 1111 is obtained. The squared value of Y0001 (i), ..., Y1111 (i) is obtained.
Then, the sum Z0000 (i) = X0000 (i) + Y0000 (i) of X0000 (i) and Y0000 (i) is obtained. Similarly, Z0001 (i), ..., Z1111 (i) are obtained. Similarly, for the time i + 1, Z0000 (i + 1), Z0001 (i + 1), ..., Z1111 (i + 1) are obtained.
Next, the certainty of the received data at time i and time i + 1 is compared.
For example, the smallest value is searched from Z0000 (i), Z0001 (i), ..., Z1111 (i). Let that value be F (i). Then search for the second smallest value. Let that value be S (i).
Similarly, the smallest value is searched for from Z0000 (i + 1), Z0001 (i + 1), ..., Z1111 (i + 1). Let that value be F (i + 1). Then search for the second smallest value. Let that value be S (i + 1).
Then, for example, R (i) = F (i) / S (i) and R (i + 1) = F (i + 1) / S (i + 1) are obtained.
When R (i + 1)> R (i), it is judged that the reception quality is better at time i, and the 4 bits giving F (i) are judged as correct data. Then, 2 bits of data transmitted by the modulation signal A at time i and time i + 1 and 2 bits of data transmitted by the modulation signal B at time i are obtained. Then, the 2 bits transmitted by the modulation signal B are determined by utilizing the fact that the 2 bits transmitted by the modulation signal A are determined, and the 2 bits transmitted by the modulation signal B are determined at the time i + 1. For example, if the 2 bits transmitted by the modulation signal A are 00, the highest value among Z0000 (i + 1), Z0001 (i + 1), Z0010 (i + 1), and Z0011 (i + 1). Search for the smaller one, and determine the 2 bits transmitted by the modulation signal B at time i + 1. Similarly, if the 2 bits transmitted by the modulation signal A is 01, the most of Z0100 (i + 1), Z0101 (i + 1), Z0110 (i + 1), and Z0111 (i + 1). Search for the one with the smaller value, and determine the 2 bits transmitted by the modulation signal B at time i + 1. Similarly, when the 2 bits transmitted by the modulation signal A are 10 and 11, the 2 bits transmitted by the modulation signal B at the time i + 1 are determined.
When R (i)> R (i + 1), it is judged that the reception quality is better at time i + 1, and the 4 bits giving F (i + 1) are judged as correct data. Then, 2 bits of data transmitted by the modulation signal A at time i and time i + 1 and 2 bits of data transmitted by the modulation signal B at time i + 1 are obtained. Then, utilizing the fact that the 2 bits transmitted by the modulation signal A are determined, the 2 bits transmitted by the modulation signal B at the time i are determined. For example, if the 2 bits transmitted by the modulation signal A are 00, the smallest value among Z0000 (i), Z0001 (i), Z0010 (i), and Z0011 (i) is searched for. Determine the 2 bits transmitted by the modulation signal B at time i. Similarly, if the 2 bits transmitted by the modulation signal A are 01, the one with the smallest value among Z0100 (i), Z0101 (i), Z0110 (i), and Z0111 (i) is searched for. , Determine the 2 bits transmitted by the modulation signal B at time i . Similarly, when the 2 bits transmitted by the modulation signal A are 10 and 11, the 2 bits transmitted by the modulation signal B at the time i are determined.
The detailed configuration of the demodulation unit 2721 in FIG. 28 is shown in FIG. The operation of FIG. 8 will be described.
As described above, the modulation signal A, B demodulation unit 608 of FIG. 8 outputs the data transmitted by the modulation signal A at the time i and the time i + 1 as the reception digital signal 524 of the modulation signal A. Further, Z0000 (i), ..., Z1111 (i) are output as the first soft judgment value signal 701. Further, Z0000 (i + 1), ..., Z1111 (i + 1) are output as the second soft judgment value signal 702. Then, the received digital signal 525-1 of the modulation signal B of either time i or time i + 1 is output.
The modulation signal B demodulation unit 703 includes Z0000 (i), ..., Z1111 (i), which is the first soft judgment value signal 701, and Z0000 (i + 1), which is the second soft judgment value signal 702., Z1111 (i + 1) is used as an input, and as described above, the modulation signal B is demodulated based on the reception quality of time i and time i + 1, and modulation of a time different from 525-1 is performed. Receive signal B Outputs digital signal 525-2.
Here, the decoding method of the carrier 1 has been described, but when the encoding is similarly performed by a carrier other than the carrier 1, if the above operation is performed in consideration of another carrier, the decoding can be performed in the same manner. That is, the carrier n component of the signal after Fourier transform in FIG. 28, the carrier n component of the channel estimation signal group of the modulated signal A, and the carrier n component of the channel estimation signal group of the modulated signal B are used to obtain the carrier n. Decryption can be performed.
Next, a case where the frame configurations shown in FIGS. 31A and 31B are adopted will be described. In the frame configurations of FIGS. 31A and 31B, coding is performed at time i and i + n. Therefore, h11 (i) h11 (i + n), h12 (i) h12 (i + n), h21 (i) h21 (i + n), h22 (i) h22 (i + n) If n such that the relationship is established, it can be carried out by performing the same processing as the frame configuration of FIGS. 29A and 29B. That is, if the operation of time i + 1 is considered as the operation of time i + n, it can be carried out in the same manner as described with reference to FIGS. 29A and 29B.
Next, a case where the frame configurations shown in FIGS. 33A and 33B are adopted will be described. At this time, it is important that the radio wave propagation environment is completely different between the times i and j because the times are completely different.
Here, the operation of the carrier 1 will be described as an example. At time i, equation (1) holds. Similarly, at time j, Eq. (3) holds. At this time, h11 (i), h12 (i), h21 (i), and h22 (i) are used in the receiving device, for example, by using the radio wave propagation environment estimation symbol 2801 at time i-1 of carrier 1 in FIG. 33A. presume. Similarly, h11 (j), h12 (j), h21 (j), h22 (j) are used in the receiver, for example, using the radio wave propagation environment estimation symbol 2801 at time j-1 of carrier 1 in FIG. 33B. presume. Here, since the radio wave propagation environment is significantly different between the times i and j, h11 (i) h11 (j), h12 (i) h12 (j), h21 (i) h21 (j). ), H22 (i) h22 (j). Therefore, the reception quality at time i and j will be completely different.
In consideration of the above, the signal point arrangement in the IQ plane of time i and time j will be described. Figures 3A to 3C show examples of signal point arrangement in the IQ plane. In the frame configuration of FIGS. 33A and 33B, the signal point arrangements of the time i and the time j may be different from each other, for example, as shown in FIG. 3A for the time i and FIG. 3B for the time j. This is different from the frame configurations shown in FIGS. 29A, 29B, 31A, and 31B. Since the radio wave propagation environment is different between the times i and j, it is not necessary to change the signal point arrangement at the times i and j. However, the reception quality will be different.
The decoding procedure will be described in detail below, but it can be considered in the same manner as the operation of the frame configuration shown in FIGS. 29A and 29B. In other words, the operation of time i + 1 should be replaced with time j.
The specific demodulation (decoding) procedure for the frame configuration signals of FIGS. 33A and 33B by the receiving device 2700 is as follows. <1> Detect for time i and obtain (S1 (i), S2 (i)). <2> Detect for time j and obtain (S1 (i), S2 (j)). <3> Compare the reception quality at time i and time j.
If the reception quality at time i is better, the data at time i (S1 (i), S2 (i)) is obtained by detection at time i. Next, S1 (i) at time j is estimated from S1 (i) obtained by detection at time i, and the result is used to obtain S2 (j).
If the reception quality at time j is better, the data at time j (S1 (i), S2 (j)) is obtained by detection at time j. Next, S1 (i) at time i is estimated from S1 (i) obtained by detection at time j, and the result is used to obtain S2 (i).
The demodulation unit 2721 in FIG. 28 obtains the received digital signal 2722 of the modulated signal A and the received digital signal 2723 of the modulated signal B by performing the above procedure.
The detailed configuration of the demodulation unit 2721 in FIG. 28 is as shown in FIG. 8, and the operation thereof will be described below.
In FIG. 8, signal 508 is signaled to 2708 of FIG. 28, signal 510 is signaled to 2710 of FIG. 28, signal 506 is signaled to 2706 of FIG. 28, signal 518 is signaled to 2718 of FIG. 28, and signal 520 is signaled to 2720 of FIG. 28. 516 corresponds to 2716 in Fig. 28.
Here, the case where the QPSK modulation signal is transmitted to both the modulation signal A and the modulation signal B in the carrier 1 in the frame configuration of FIGS. 33A and 33B in the transmission device 2600 of FIG. 27 will be described as an example.
A total of 4 bits, 2 bits for the modulated signal A and 2 bits for the modulated signal B, can be transmitted. That is, 0000, 0001, ..., 1111 can be transmitted. However, the upper 2 bits are the 2 bits transmitted by the modulation signal A, and the lower 2 bits are the 2 bits transmitted by the modulation signal B.
Here, the operation of the demodulation unit 2721 in FIG. 28 will be described.
At time i, the demodulator 2721 uses the carrier 1 component of the transmission line estimation signal group 2708 of the modulation signal A and the carrier 1 component of the transmission line estimation signal group 2710 of the modulation signal B to use 0000,0001, ... Find the signal points in the IQ plane of 16 signal points of 1111. The state at that time corresponds to the 16 signal points 1302 in FIG.
Then, the reception state in the IQ plane can be obtained from the component of the carrier 1 of the signal 2706 after the Fourier transform. The state at that time corresponds to the signal point of 1301 in FIG.
Next, for example, the square value of the distance in the IQ plane of all the signal points and the signal points 1301 shown in 1302 in FIG. 14 is calculated. That is, the square value X0000 (i) of the distance between the signal point 1302 of the transmission bit 0000 and the signal point 1301 is obtained, and similarly, the distance between the signal point 1302 and the signal point 1301 of the transmission bits 0001, ..., 1111 is obtained. The squared value of X0001 (i), ..., X1111 (i) is obtained.
Similarly, at time i in FIGS. 33A and 33B, the component of carrier 1 of the transmission line estimation signal group 2718 of the modulation signal A and the component of carrier 1 of the transmission line estimation signal group 2720 of the modulation signal B are used. Find the signal points in the IQ plane of 16 signal points of 0001, ···, 1111. The state at that time corresponds to the 16 signal points 1302 in FIG.
Then, the reception state in the IQ plane can be obtained from the component of carrier 1 of the signal 2716 after the Fourier transform. The state at that time corresponds to the signal point shown by 1301 in FIG.
Next, for example, the square value of the distance in the IQ plane of all the signal points and the signal points 1301 shown in 1302 in FIG. 14 is calculated. That is, the square value Y0000 (i) of the distance between the signal point 1302 of the transmission bit 0000 and the signal point 1301 is obtained, and similarly, the distance between the signal point 1302 and the signal point 1301 of the transmission bits 0001, ..., 1111 is obtained. The squared value of Y0001 (i), ..., Y1111 (i) is obtained.
Then, the sum Z0000 (i) = X0000 (i) + Y0000 (i) of X0000 (i) and Y0000 (i) is obtained. Similarly, Z0001 (i), ..., Z1111 (i) are obtained. Similarly, for time j, Z0000 (j), Z0001 (j), ..., Z1111 (j) are obtained.
Here, when making a determination at time i, the radio wave propagation environment is estimated using, for example, the carrier 1 symbol of the radio wave propagation environment estimation symbol 2801 at time i-1 in FIGS. 33A and 33B. On the other hand, when determining the time j, the radio wave propagation environment is estimated using, for example, the carrier 1 symbol of the radio wave propagation environment estimation symbol 2801 at time j-1 in FIGS. 33A and 33B.
Next, the certainty of the received data at time i and time j is compared.
For example, the smallest value is searched from Z0000 (i), Z0001 (i), ..., Z1111 (i). Let that value be F (i). Then search for the second smallest value. Let that value be S (i).
Similarly, the smallest value is searched for from Z0000 (j), Z0001 (j), ..., Z1111 (j). Let that value be F (j). Then search for the second smallest value. Let that value be S (j).
Then, for example, R (i) = F (i) / S (i) and R (j) = F (j) / S (j) are obtained.
When R (j)> R (i), it is judged that the reception quality is better at time i, and the 4 bits giving F (i) are judged as correct data. Then, 2 bits of data transmitted by the modulation signal A at time i and time j and 2 bits of data transmitted by the modulation signal B at time i are obtained. Then, utilizing the fact that the 2 bits transmitted by the modulation signal A are determined, the 2 bits transmitted by the modulation signal B at the time j are determined. For example, if the 2 bits transmitted by the modulation signal A are 00, the smallest of Z0000 (j), Z0001 (j), Z0010 (j), and Z0011 (j) is searched for, and the time j 2 bits transmitted by the modulation signal B are determined. Similarly, if the 2 bits transmitted by the modulation signal A are 01, the smallest of Z0100 (j), Z0101 (j), Z0110 (j), and Z0111 (j) is searched for, and the time is Determine the 2 bits transmitted by the modulation signal B to i + 1. Similarly, when the 2 bits transmitted by the modulation signal A are 10 and 11, the 2 bits transmitted by the modulation signal B at time j are determined.
When R (i)> R (j), it is judged that the reception quality is better at time j, and the 4 bits giving F (j) are judged to be correct data. Then, 2 bits of data transmitted by the modulation signal A at time i and time j and 2 bits of data transmitted by the modulation signal B at time j are obtained. Then, the 2 bits transmitted by the modulated signal B are determined by utilizing the fact that the 2 bits transmitted by the modulated signal A are determined, and the 2 bits transmitted by the modulated signal B are determined at the time i. For example, if the 2 bits transmitted by the modulation signal A are 00, the smallest of Z0000 (i), Z0001 (i), Z0010 (i), and Z0011 (i) is searched for, and the time i 2 bits transmitted by the modulation signal B are determined. Similarly, if the 2 bits transmitted by the modulation signal A are 01, the smallest of Z0100 (i), Z0101 (i), Z0110 (i), and Z0111 (i) is searched for, and the time is Determine the 2 bits transmitted by the modulation signal B to i. Similarly, when the 2 bits transmitted by the modulation signal A are 10 and 11, the 2 bits transmitted by the modulation signal B at the time i are determined.
The detailed configuration of the demodulation unit 2721 in FIG. 28 is shown in FIG. The operation of FIG. 8 will be described.
As described above, the modulation signal A, B demodulation unit 608 of FIG. 8 outputs the data transmitted by the modulation signal A at the time i and the time j as the reception digital signal 524 of the modulation signal A. Further, Z0000 (i), ..., Z1111 (i) are output as the first soft judgment value signal 701. Further, Z0000 (j), ..., Z1111 (j) are output as the second soft judgment value signal 702. Then, the received digital signal 525-1 of the modulation signal B of either time i or time j is output.
The modulation signal B demodulation unit 703 includes the first soft judgment value signal 701, Z0000 (i), ..., Z1111 (i) and the second soft judgment value signal 702, Z0000 (j), ... , Z1111 (j) is input, and as described above, the modulated signal B is demodulated based on the reception quality of time i and time j, and the received digital signal of the modulated signal B at a time different from 525-1. Output 525-2.
Here, the demodulation of the modulated signal A and the modulated signal B of the time i and the time j of the carrier 1 has been described, but it can be carried out by performing the same processing even when the same coding is performed in other than the carrier 1. Is.
Next, the operation when coding in the frequency axis direction, which is possible when a multi-carrier method such as the OFDM method is used, will be described in detail. That is, what has been coded in the time axis direction described above is coded in the frequency axis direction.
A case where the frame configurations shown in FIGS. 30A and 30B are adopted will be described. The feature of the frame configuration of FIGS. 30A and 30B is that in the modulated signal A, the same data is transmitted for carriers 1 and 2 with symbols S1 (i) and S1 (i)'with different signal point arrangements at time i. The modulation signal B is a point in which different data for carriers 1 and 2 are transmitted by symbols S2 (i-1) and S2 (i-2) at time i.
Figures 3A to 3C show the signal point arrangement in the IQ plane of S1 (i) and S1 (i)'. The modulation method is QPSK. For example, in FIG. 30A, it is assumed that (0,0) is transmitted as information of S1 (i) at carrier 1 and time i. At this time, the signal points are as shown in FIG. 3A. Then, at carrier 2 and time i, (0,0) is transmitted as information as shown in FIG. 3B, for example. The same applies to (0,1), (1,0), and (1,1). However, the arrangement of signal points for carrier 2 and time i is not limited to FIG. 3B, and may be transmitted in FIG. 3C. In this way, at time i, carrier 1 and carrier 2 transmit the same information with different signal point arrangements.
By doing so, focusing on the time i, the signal point arrangement of the received modulated signal in the receiving device changes between the carrier 1 and the carrier 2, so that the accuracy of demodulation of the modulated signal A and the modulated signal B in the carrier 1 And the demodulation accuracy of the modulated signal A and the modulated signal B in the carrier 2 will be different. Then, the modulation signal A is demodulated at a time with good demodulation accuracy, and the modulation signal B is demodulated using the result, so that the demodulation accuracy of the modulation signal B can be improved. That is, the demodulation accuracy of both the modulated signals A and B can be improved.
The operation of the transmitting device 2600 when the transmitting device 2600 forms the modulated signals A and B having the frame configurations of FIGS. 30A and 30B will be described.
The frame configuration signal generation unit 2623 outputs the frame configuration information of FIGS. 30A and 30B as the frame configuration signal 2624. The coding unit 2602 receives the transmission digital signal 2601 and the frame configuration signal 2624 as inputs, encodes the transmission digital signal 2601 as in the frame configuration of the modulation signal A of FIG. 30A, and outputs the encoded digital signal 2603.
The modulation unit 2625 takes the encoded digital signal 2603 and the frame configuration signal 2624 as inputs, and outputs a transmission orthogonal baseband signal 2626 according to the frame configuration of the modulation signal A of FIG. 30A. The modulation unit 2625 may have a configuration as shown in FIG. 5, for example.
In FIG. 5, the mapping unit X402 maps the signal points as shown in FIG. 3A. The mapping unit Y404 maps the signal points as shown in FIG. 3B or FIG. 3C.
For example, when focusing on the time i in the frame configuration of FIG. 30A, when the frame configuration signal 2624 indicates the symbols of the modulation signal A, the carrier 1, and the time i, the mapping unit X402 refers to the input digital signal. , Maps and outputs the first mapped transmit orthogonal baseband signal 403.
On the other hand, when the frame configuration signal 2624 indicates the symbols of the modulation signal A, the carrier 2, and the time i, the mapping unit Y404 performs mapping on the input digital signal and performs a second mapping. The transmission orthogonal baseband signal 405 is output.
The signal selection unit 407 includes a first mapped transmission orthogonal baseband signal 403, a second mapped transmission orthogonal baseband signal 405, and a frame configuration signal.<u style="single">324</u>Is used as an input, and the frame configuration signal<u style="single">324</u>Selects the signal indicated by and outputs the selected transmission orthogonal baseband signal 408.
Here, the frame configuration of FIGS. 30A and 30B, that is, the case of coding over the carrier 1 and the carrier 2 at the time i has been described as an example, but as shown in FIGS. 32A and 32B, the carrier 1 and the carrier 1 have been described. The same can be performed when the code is encoded over the carrier n. That is, in the above description, if the operation of the carrier 2 is considered as the operation of the carrier n, it can be carried out in the same manner. Further, although the explanation focused on the time i, the same coding can be performed even if the same coding is applied at a time other than the time i, and further, the carriers other than the carrier 1 and the carrier 2 can be carried out at the time i. It can be carried out in the same manner even if it is encoded.
Next, the configuration of the receiving device will be described. FIG. 28 shows the configuration of the receiving device according to the present embodiment. The receiving antenna 2701 of FIG. 28 corresponds to the antenna 109 of FIG. 2B, and the receiving antenna 2711 corresponds to the antenna 110 of FIG. 2B.
In the following, the operation at time i will be described as an example. First, carrier 1 will be described. The modulation signal A transmission line estimation unit 2707 of FIG. 28 obtains the channel variation h11,1 (t) of the carrier 1 by using the modulation signal A of FIG. 30A, the carrier 1, and the radio wave propagation environment estimation symbol 2801 at time i. However, t is time. Similarly, the modulation signal B transmission line estimation unit 2709 obtains the channel variation h12,1 (t) of the carrier 1 by using the modulation signal B, the carrier 1, and the radio wave propagation environment estimation symbol 2801 at time i in FIG. 30B. The modulation signal A transmission line estimation unit 2717 obtains the channel variation h21,1 (t) of the carrier 1 by using the modulation signal A, the carrier 1, and the radio wave propagation environment estimation symbol 2801 at time i in FIG. 30A. Similarly, the modulation signal B transmission line estimation unit 2719 obtains the channel variation h22,1 (t) of the carrier 1 by using the modulation signal B of FIG. 30B, the carrier 1, and the radio wave propagation environment estimation symbol 2801 at time i.
Then, at time i, if the signal of the carrier 1 received by the receiving antenna 2701 is R1,1 (i) and the signal of the carrier 1 received by the receiving antenna 2711 is R2,1 (i), the following equation is established.<maths num="11"><img file="JP4445467B2_D0011.tif" /></maths>
Similarly, in carrier 2, the following equation holds.<maths num="12"><img file="JP4445467B2_D0012.tif" /></maths>
S1 (i) and S2 (i-1) can be obtained from the relationship of Eq. (11), and S1 (i)'and S2 (i-2) can be obtained from the relationship of Eq. (12).
Also, h11,1 (i) h11,2 (i), h12,1 (i) h12,2 (i), h21,1 (i) h21,2 (i), h22,1 (i) h22,2 (i) holds. At this time, the matrices of Eqs. (11) and (12) are almost equal, but the vectors of (S1 (i), S2 (i-1)) and (S1 (i)', S2 (i-) Since the vectors of 2)) are different, the certainty of the obtained data will be different.
In the present embodiment, this characteristic is used to improve the quality of received data. The specific demodulation (decoding) procedure of the receiving device 2700 is as follows. <1> Detect carrier 1 for time i to obtain (S1 (i), S2 (i-1)). <2> At time i, carrier 2 is detected to obtain (S1 (i)', S2 (i-2)). <3> Compare the reception quality of carrier 1 and carrier 2.
If the reception quality of carrier 1 is better, the data of (S1 (i), S2 (i-1)) is obtained by the detection of carrier 1. Next, S1 (i)'of carrier 2 is estimated from S1 (i) obtained by detection of carrier 1, and the result is used to obtain S2 (i-2).
If the reception quality of carrier 2 is better, the data of (S1 (i)', S2 (i-2)) is obtained by the detection of carrier 2. Next, S1 (i) of carrier 1 is estimated from S1 (i)'obtained by detection of carrier 2, and the result is used to obtain S2 (i-1).
In the receiving device 2700, the demodulation unit 2721 performs such demodulation processing to obtain the received digital signal 2722 of the modulated signal A and the received digital signal 2723 of the modulated signal B.
The detailed configuration of the demodulation unit 2721 in FIG. 28 is as shown in FIG. 8, and the operation thereof will be described below.
In FIG. 8, signal 508 is signaled to 2708 of FIG. 28, signal 510 is signaled to 2710 of FIG. 28, signal 506 is signaled to 2706 of FIG. 28, signal 518 is signaled to 2718 of FIG. 28, and signal 520 is signaled to 2720 of FIG. 28. 516 corresponds to 2716 in Fig. 28.
Here, in the transmission device 2600 of FIG. 27, a case where both the modulation signal A and the modulation signal B are modulated by QPSK in the frame configurations of FIGS. 30A and 30B will be described as an example. However, this is an explanation of carrier 1 and carrier 2.
A total of 4 bits, 2 bits for the modulated signal A and 2 bits for the modulated signal B, can be transmitted. That is, 0000, 0001, ..., 1111 can be transmitted. However, the upper 2 bits are the 2 bits transmitted by the modulation signal A, and the lower 2 bits are the 2 bits transmitted by the modulation signal B.
Here, the operation of the demodulation unit 2721 in FIG. 28 will be described.
The demodulator 2721 uses the carrier 1 component of the transmission line estimation signal group 2708 of the modulation signal A and the carrier 1 component of the transmission line estimation signal group 2710 of the modulation signal B at carrier 1 and time i, 0000,0001. Find the signal points in the IQ plane of the 16 signal points of, ..., 1111. The state at that time corresponds to the 16 signal points 1302 in FIG.
Then, the reception state in the IQ plane can be obtained from the component of the carrier 1 of the signal 2706 after the Fourier transform. The state at that time corresponds to the signal point 1301 shown in FIG.
Next, for example, the square value of the distance in the IQ plane of all the signal points 1302 and the signal point 1301 shown in FIG. 14 is calculated. That is, the square value X0000 (i) of the distance between the signal point 1302 of the transmission bit 0000 and the signal point 1301 is obtained, and similarly, the distance between the signal point 1302 and the signal point 1301 of the transmission bits 0001, ..., 1111 is obtained. The squared value of X0001 (i), ..., X1111 (i) is obtained.
Similarly, in the carrier 1 and time i of FIGS. 30A and 30B, the component of carrier 1 of the transmission line estimation signal group 2718 of the modulation signal A and the component of carrier 1 of the transmission line estimation signal group 2720 of the modulation signal B are used. , 0000, 0001, ···, 1111 16 signal points in the IQ plane are obtained. The state at that time corresponds to the 16 signal points 1302 in FIG.
Then, the reception state in the IQ plane can be obtained from the component of carrier 1 of the signal 2716 after the Fourier transform. The state at that time corresponds to the signal point 1301 in FIG.
Next, for example, the square value of the distance in the IQ plane of all the signal points 1302 and the signal point 1301 shown in FIG. 14 is calculated. That is, the square value Y0000 (i) of the distance between the signal point 1302 of the transmission bit 0000 and the signal point 1301 is obtained, and similarly, the distance between the signal point 1302 and the signal point 1301 of the transmission bits 0001, ..., 1111 is obtained. The squared value of Y0001 (i), ..., Y1111 (i) is obtained.
Then, the sum Z0000 (i) = X0000 (i) + Y0000 (i) of X0000 (i) and Y0000 (i) is obtained. Similarly, Z0001 (i), ..., Z1111 (i) are obtained. Similarly, for carrier 2, Z0000 (i), Z0001 (i), ..., Z1111 (i) are obtained.
Next, the certainty of the received data between the carrier 1 and the carrier 2 is compared.
For example, in carrier 1, the smallest value is searched from among Z0000 (i), Z0001 (i), ..., Z1111 (i). Let that value be F (i). Then search for the second smallest value. Let that value be S (i).
Similarly, in carrier 2, the smallest value is searched from among Z0000 (i), Z0001 (i), ..., Z1111 (i). Let that value be F (i). Then search for the second smallest value. Let that value be S (i).
Then, for example, R, 1 (i) = F (i) / S (i) is obtained in the carrier 1, and R, 2 (i) = F (i) / S (i) is obtained in the carrier 2.
When R, 2 (i)> R, 1 (i), it is judged that the carrier 1 has better reception quality, and the 4 bits giving F (i) of the carrier 1 are judged to be correct data. Then, 2 bits of data transmitted by the modulation signal A to the carrier 1 and the carrier 2 and 2 bits of data transmitted by the modulation signal B of the carrier 1 are obtained. Then, the 2 bits transmitted by the modulated signal B of the carrier 2 are determined by utilizing the fact that the 2 bits transmitted by the modulated signal A are determined. For example, if the 2 bits transmitted by the modulation signal A are 00, the smallest carrier 2 Z0000 (i), Z0001 (i), Z0010 (i), and Z0011 (i) is searched for. , Determines the 2 bits transmitted by the modulation signal B of carrier 2. Similarly, if the 2 bits transmitted by the modulation signal A are 01, the smallest of the carriers 2 Z0100 (i), Z0101 (i), Z0110 (i), and Z0111 (i) is searched for. Then, the 2 bits transmitted by the modulation signal B of the carrier 2 are determined. Similarly, when the 2 bits transmitted by the modulation signal A are 10 and 11, the 2 bits transmitted by the modulation signal B of the carrier 2 are determined.
When R, 1 (i)> R, 2 (i), it is judged that the carrier 2 has better reception quality, and the 4 bits giving F (i) of the carrier 2 are judged to be correct data. Then, 2 bits of data transmitted by the modulation signal A to the carrier 1 and the carrier 2 and 2 bits of data transmitted by the modulation signal B of the carrier 2 are obtained. Then, the 2 bits transmitted by the modulated signal B of the carrier 1 are determined by utilizing the fact that the 2 bits transmitted by the modulated signal A are determined. For example, if the 2 bits transmitted by the modulation signal A are 00, the smallest carrier 1 Z0000 (i), Z0001 (i), Z0010 (i), and Z0011 (i) is searched for. , Determines the 2 bits transmitted by the modulation signal B of carrier 1. Similarly, if the 2 bits transmitted by the modulation signal A are 01, the smallest of the carriers 1 Z0100 (i), Z0101 (i), Z0110 (i), and Z0111 (i) is searched for. Then, the 2 bits transmitted by the modulation signal B of the carrier 1 are determined. Similarly, when the 2 bits transmitted by the modulation signal A are 10 and 11, the 2 bits transmitted by the modulation signal B of the carrier 1 are determined.
The detailed configuration of the demodulation unit 2721 in FIG. 28 is shown in FIG. The operation of FIG. 8 will be described.
As described above, the modulation signal A, B demodulation unit 608 of FIG. 8 outputs the data transmitted by the modulation signal A in the carrier 1 and the carrier 2 at time i as the reception digital signal 524 of the modulation signal A. Further, as the first soft determination value signal 701, Z0000 (i), ..., Z1111 (i) of the carrier 1 are output. Further, Z0000 (i), ..., Z1111 (i) of the carrier 2 are output as the second soft judgment value signal 702. Then, the received digital signal 525-1 of the modulation signal B of either carrier 1 or carrier 2 at time i is output.
The modulation signal B demodulation unit 703 includes Z0000 (i), ..., Z1111 (i) of carrier 1 which is the first soft judgment value signal 701 and Z0000 (Z0000 (i) of carrier 2 which is the second soft judgment value signal 702. With i), ..., Z1111 (i) as inputs, the modulation signal B is demodulated based on the reception quality of carrier 1 and carrier 2 as described above, and modulation of a carrier different from 525-1 is performed. Receive signal B Outputs digital signal 525-2.
Here, the decoding method of the carrier 1 and the carrier 2 has been described, but even if the carriers other than the carrier 1 and the carrier 2 are encoded in the same manner, the decoding can be performed in the same manner by performing the same operation as described above. it can.
When the frame configurations shown in FIGS. 32A and 32B are adopted, h11,1 (i) h11,1 + n (i), h12,1 (i) h12,1 + n (i), h21,1 ( If n such that the relationship of i) h21,1 + n (i), h22,1 (i) h22,1 + n (i) is established, the case of the frame configuration of FIGS. 30A and 30B By performing the same processing, it can be carried out in the same manner. That is, if the operation of the carrier 2 is considered as the operation of the carrier 1 + n, it can be carried out in the same manner.
Next, a case where the frame configurations shown in FIGS. 34A and 34B are adopted will be described. In the case of the frame configurations of FIGS. 34A and 34B, it is important that the radio wave propagation environment is completely different between the carrier 1 and the carrier j because the frequencies are completely different.
Here, carrier 1 and carrier j will be described as an example. At time i and carrier 1, (11) holds. At time i and carrier j, the following equation holds.<maths num="13"><img file="JP4445467B2_D0013.tif" /></maths>
At this time, h11,1 (i), h12,1 (i), h21,1 (i), h22,1 (i) are shown in the receiving device, for example, in the time i- of the carrier 1 of FIGS. 34A and 34B. Estimate using the radio wave propagation environment estimation symbol 2801 of 1. Similarly, h11, j (i), h12, j (i), h21, j (i), h22, j (i) in the receiver, for example, the time i- of the carrier j in FIGS. 34A, 34B. Estimate using the radio wave propagation environment estimation symbol 2801 of 1. At this time, since the radio wave propagation environment is different between carriers 1 and j, h11,1 (i) h11, j (i), h12,1 (i) h12, j (i), h21 , 1 (i) h21, j (i), h22,1 (i) h22, j (i) holds. Therefore, the reception quality of carriers 1 and j will be completely different.
In consideration of the above, the arrangement of signal points on the IQ plane of carrier 1 and carrier j will be described. Figures 3A to 3C show an example of signal point arrangement on the IQ plane. In the frame configuration of FIGS. 34A and 34B, the signal point arrangements of the carrier 1 and the carrier j may be different, for example, FIG. 3A, the carrier 1 as shown in FIG. 3A, and the carrier j as shown in FIG. 3B. .. This is different from the frame configurations shown in FIGS. 29A and 29B and 31A and 31B. Since the radio wave propagation environment differs between carrier 1 and carrier j, the signal point arrangement is intentionally placed between carrier 1 and carrier j. This is because the reception quality will be different even if it is not changed.
The decoding procedure will be described in detail below, but it can be considered in the same manner as the operation of the frame configuration shown in FIGS. 30A and 30B. That is, the operation of carrier 2 may be replaced with carrier j.
The specific demodulation (decoding) procedure of the frame configuration signals of FIGS. 34A and 34B by the receiving device 2700 is as follows. <1> Detect carrier 1 for time i to obtain (S1 (i), S2 (i-1)). <2> At time i, the carrier j is detected and (S1 (i), S2 (ij)) is obtained. <3> Compare the reception quality of carrier i and carrier j.
If the reception quality of time i and carrier 1 is better, the data of (S1 (i), S2 (i-1)) is obtained by the detection of time i and carrier 1. Next, S1 (i) of the time i carrier j is estimated from S1 (i) obtained by the detection of the time i and the carrier 1, and the result is used to obtain S2 (ij).
If the reception quality of time i and carrier j is better, the data of (S1 (i), S2 (ij)) is obtained by the detection of time i and carrier j. Next, S1 (i) of time i and carrier 1 is estimated from S1 (i) obtained by detection of time i carrier j, and the result is used to obtain S2 (i-1).
The demodulation unit 2721 in FIG. 28 obtains the received digital signal 2722 of the modulated signal A and the received digital signal 2723 of the modulated signal B by performing the above procedure.
The detailed configuration of the demodulation unit 2721 in FIG. 28 is as shown in FIG. 8, and the operation thereof will be described below.
In FIG. 8, signal 508 is signaled to 2708 of FIG. 28, signal 510 is signaled to 2710 of FIG. 28, signal 506 is signaled to 2706 of FIG. 28, signal 518 is signaled to 2718 of FIG. 28, and signal 520 is signaled to 2720 of FIG. 28. 516 corresponds to 2716 in Fig. 28.
Here, in the transmission device 2600 of FIG. 27, the case where the modulation signal A and the modulation signal B are both transmitted by QPSK modulation in the carrier 1 and the carrier j in the frame configuration of FIGS. 34A and 34B will be described as an example.
A total of 4 bits, 2 bits for the modulated signal A and 2 bits for the modulated signal B, can be transmitted. That is, 0000, 0001, ..., 1111 can be transmitted. However, the upper 2 bits are the 2 bits transmitted by the modulation signal A, and the lower 2 bits are the 2 bits transmitted by the modulation signal B.
Here, the operation of the demodulation unit 2721 in FIG. 28 will be described.
At time i, the demodulator 2721 uses the carrier 1 component of the transmission line estimation signal group 2708 of the modulation signal A and the carrier 1 component of the transmission line estimation signal group 2710 of the modulation signal B to use 0000,0001, ... Find the signal points in the IQ plane of 16 signal points of 1111. The state at that time corresponds to the 16 signal points 1302 in FIG.
Then, the reception state in the IQ plane can be obtained from the component of the carrier 1 of the signal 2706 after the Fourier transform. The state at that time corresponds to the signal point 1301 in FIG.
Next, for example, the square value of the distance in the IQ plane of all the signal points 1302 and the signal point 1301 shown in FIG. 14 is calculated. That is, the square value X0000 (i) of the distance between the signal point 1302 of the transmission bit 0000 and the signal point 1301 is obtained, and similarly, the distance between the signal point 1302 and the signal point 1301 of the transmission bits 0001, ..., 1111 is obtained. The squared value of X0001 (i), ..., X1111 (i) is obtained.
Similarly, at time i in FIGS. 34A and 34B, the component of carrier 1 of the transmission line estimation signal group 2718 of the modulation signal A and the component of carrier 1 of the transmission line estimation signal group 2720 of the modulation signal B are used. Find the signal points in the IQ plane of 16 signal points of 0001, ···, 1111. The state at that time corresponds to the 16 signal points 1302 in FIG.
Then, the reception state in the IQ plane can be obtained from the component of carrier 1 of the signal 2716 after the Fourier transform. The state at that time corresponds to the signal point 1301 in FIG.
Next, for example, the square value of the distance in the IQ plane of all the signal points 1302 and the signal point 1301 shown in FIG. 14 is calculated. That is, the square value Y0000 (i) of the distance between the signal point 1302 of the transmission bit 0000 and the signal point 1301 is obtained, and similarly, the distance between the signal point 1302 and the signal point 1301 of the transmission bits 0001, ..., 1111 is obtained. The squared value of Y0001 (i), ..., Y1111 (i) is obtained.
Then, the sum Z0000 (i) = X0000 (i) + Y0000 (i) of X0000 (i) and Y0000 (i) is obtained. Similarly, Z0001 (i), ..., Z1111 (i) are obtained.
Here, when making a determination at time i, the radio wave propagation environment is estimated using, for example, the symbols of carrier 1 and carrier j of the radio wave propagation environment estimation symbol 2801 at time i-1 in FIGS. 34A and 34B. ..
Next, the certainty of the received data of carrier 1 and carrier j at time i is compared.
For example, the smallest value is searched for from Z0000 (i), Z0001 (i), ..., Z1111 (i) of carrier 1. Let that value be F (i). Then search for the second smallest value. Let that value be S (i).
Similarly, the smallest value is searched for from Z0000 (i), Z0001 (i), ..., Z1111 (i) of the carrier j. Let that value be F (i). Then search for the second smallest value. Let that value be S (i).
Then, for example, R (i) = F (i) / S (i) of the carrier 1 and R (i) = F (i) / S (i) of the carrier j are obtained.
When R (i) of carrier j> R (i) of carrier 1, it is judged that carrier 1 has better reception quality, and 4 bits giving F (i) of carrier 1 are judged to be correct data. Then, 2 bits of data transmitted by the modulation signal A to the carrier 1 and the carrier j and 2 bits of data transmitted by the modulation signal B of the carrier 1 are obtained. Then, the 2 bits transmitted by the modulation signal B of the carrier j are determined by utilizing the fact that the 2 bits transmitted by the modulation signal A are determined.
For example, if the 2 bits transmitted by the modulation signal A are 00, the smallest carrier j among Z0000 (i), Z0001 (i), Z0010 (i), and Z0011 (i) is searched for. , Determines the 2 bits transmitted by the modulation signal B of carrier j. Similarly, if the 2 bits transmitted by the modulation signal A are 01, the smallest of the carriers j Z0100 (i), Z0101 (i), Z0110 (i), and Z0111 (i) is searched for. Then, the 2 bits transmitted by the modulation signal B of the carrier j are determined. Similarly, when the 2 bits transmitted by the modulation signal A are 10 and 11, the 2 bits transmitted by the modulation signal B of the carrier j are determined.
When R (i) of carrier 1> R (i) of carrier j, it is judged that the carrier j has better reception quality, and the 4 bits that give F (i) of carrier j are judged to be correct data, and the carrier is used. 2 bits of data transmitted by the modulation signal A of carrier j and 2 bits of data transmitted by the modulation signal B of carrier j are obtained.
Then, the 2 bits transmitted by the modulated signal B of the carrier 1 are determined by utilizing the fact that the 2 bits transmitted by the modulated signal A are determined. For example, if the 2 bits transmitted by the modulation signal A are 00, the smallest carrier 1 Z0000 (i), Z0001 (i), Z0010 (i), and Z0011 (i) is searched for. , Determines the 2 bits transmitted by the modulation signal B of carrier 1. Similarly, if the 2 bits transmitted by the modulation signal A are 01, the smallest of the carriers 1 Z0100 (i), Z0101 (i), Z0110 (i), and Z0111 (i) is searched for. Then, the 2 bits transmitted by the modulation signal B of the carrier 1 are determined. Similarly, when the 2 bits transmitted by the modulation signal A are 10 and 11, the 2 bits transmitted by the modulation signal B at the time i are determined.
The detailed configuration of the demodulation unit 2721 in FIG. 28 is shown in FIG. The operation of FIG. 8 will be described.
As described above, the modulation signal A, B demodulation unit 608 of FIG. 8 outputs the data transmitted by the modulation signal A in the carrier 1 and the carrier j as the reception digital signal 524 of the modulation signal A. Further, as the first soft determination value signal 701, Z0000 (i), ..., Z1111 (i) of the carrier 1 are output. Further, Z0000 (i), ..., Z1111 (i) of the carrier j are output as the second soft judgment value signal 702. Then, the received digital signal 525-1 of the modulation signal B of either carrier 1 or carrier j is output.
The modulation signal B demodulation unit 703 includes Z0000 (i), ..., Z1111 (i) of the carrier 1 which is the first soft judgment value signal 701 and Z0000 (Z0000 (i) of the carrier j which is the second soft judgment value signal 702. With i), ..., Z1111 (i) as inputs, the modulation signal B is demodulated based on the reception quality of carrier 1 and carrier j as described above, and modulation of a carrier different from 525-1 is performed. Receive signal B Outputs digital signal 525-2.
Here, the demodulation of the modulated signal A and the modulated signal B of the carrier 1 and the carrier j at the time i has been described, but the same processing can be performed even when the same coding is performed for the carriers other than the carrier 1 and the carrier j. It is possible to carry out.
35A and 35B show an example of the frame configuration when the frame configuration of FIG. 10A is applied to the OFDM method. If the same processing as the processing for the frame configuration signal of FIG. 10A described in the first embodiment is performed, , The OFDM method can also be carried out in the same manner.
36A and 36B are frame configurations when the frame configurations of FIGS. 35A and 35B are coded in the time direction, whereas they are coded in the frequency axis direction. The processing for the frame configuration signals of FIGS. 36A and 36B can be carried out by fusing the processing described in the first embodiment and the processing described in the present embodiment.
37A and 37B show an example of the frame configuration when the frame configuration of FIG. 10B is applied to the OFDM method. If the same processing as the processing for the frame configuration signal of FIG. 10B described in the first embodiment is performed, , The OFDM method can also be carried out in the same manner.
38A and 38B are frame configurations when the frame configurations of FIGS. 37A and 37B are coded in the time direction, whereas they are coded in the frequency axis direction. The processing for the frame configuration signals of FIGS. 38A and 38B can be carried out by fusing the processing described in the first embodiment and the processing described in the present embodiment.
Figures 39A to 39C show examples of frame configurations when the frame configuration of FIG. 15 is applied to the OFDM method. If the same processing as the processing for the frame configuration signal of FIG. 15 described in the second embodiment is performed, the same processing can be performed in the OFDM method.
40A to 40C are frame configurations when the frame configurations of FIGS. 39A to 39C are coded in the time direction, whereas they are coded in the frequency axis direction. The processing for the frame configuration signals of FIGS. 40A to 40C can be carried out by fusing the processing described in the second embodiment and the processing described in the present embodiment.
41A to 41C show an example of a frame configuration when the frame configuration of FIG. 16 is applied to the OFDM method, and can be implemented in the OFDM method as well as in the second embodiment.
42A to 42C are frame configurations when the frame configurations of FIGS. 41A to 41C are coded in the time direction, whereas they are coded in the frequency axis direction. The processing for the frame configuration signals of FIGS. 42A to 42C can be carried out by fusing the processing described in the second embodiment and the processing described in the present embodiment.
FIGS. 43A to 43C show an example of a frame configuration when the frame configuration of FIG. 22 is applied to the OFDM method, and can be implemented in the OFDM method as well as in the second embodiment.
44A to 44C are frame configurations when the frame configurations of FIGS. 43A to 43C are coded in the time direction, whereas they are coded in the frequency axis direction. The processing for the frame configuration signals of FIGS. 44A to 44C can be carried out by fusing the processing described in the second embodiment and the processing described in the present embodiment.
FIGS. 45A to 45C show an example of a frame configuration when the frame configuration of FIG. 26 is applied to the OFDM method. If the frame configuration is carried out in the same manner as in the second embodiment, it can also be carried out in the OFDM method.
46A to 46C are frame configurations when the frame configurations of FIGS. 45A to 45C are coded in the time direction, whereas they are coded in the frequency axis direction. The processing for the frame configuration signals of FIGS. 46A to 46C can be carried out by fusing the processing described in the second embodiment and the processing described in the present embodiment.
35A and 35B, 36A and 36B, 39A to 39C, 40A to 40C, 43A to 43C, 44A to 44C, adjacent symbols on the time or frequency axis. However, the description is not limited to this, and the same can be applied to cases where the symbols are 2, 3, ..., N symbols apart.
The configuration of the transmitter is not limited to the configuration of FIG. 27, and the configuration of the modulation unit is not limited to the configuration of FIG. The configuration of the receiving device and the demodulation unit is not limited to the configurations shown in FIGS. 8 and 28.
(4) Embodiment 4 In the above-described first to third embodiments, at least one of the modulated signals transmitted from each antenna is modulated a plurality of times with the same data by changing the signal point arrangement method in the time direction or the frequency direction. Mainly proposed to form by.
In this embodiment, the present invention is like a line-of-sight environment if the signal point arrangement of at least one modulated signal is changed in the time direction or the frequency direction without changing the signal point arrangement of the same data. Explain that it is effective in such cases.
In the present embodiment, since the modulated signal is formed without modulating the same data a plurality of times, the data transmission efficiency can be improved as compared with the first to third embodiments.
Further, in the present embodiment, as a preferred example, it is proposed that, in addition to the configurations of the first to third embodiments, the transmission data is further subjected to interleaving processing, and the method of arranging the signal points is changed in a predetermined block unit.
FIGS. 47A and 47B show an application example of interleaving in the present embodiment. FIG. 47A shows the order of the data before interleaving. Figure 47B shows the data sequence after interleaving. In the example shown in FIGS. 47A and 47B, interleaving is performed by reading data sequentially from left to right in the vertical direction. Specifically, the data is rearranged in the order of data 1, data 101, data 201, data 2, data 102, data 202, ..., data 100, data 200, and data 300 (this data arrangement is changed to "". Name it pattern X ).
FIGS. 48A to 48C show an example of signal point arrangement of the data sorted as shown in FIG. 47B. 48A, 48B, and 48C show examples of signal point arrangements of the modulation signal A and the modulation signal B, respectively.
Here, it is assumed that the signal point arrangements of the first to 100th symbols of the pattern X in the IQ plane are as shown in FIG. 48A for the modulated signals A and B, respectively. At this time, it is assumed that the phase formed by the signal point and the I axis is 45 degrees for both the modulated signals A and B.
It is assumed that the signal point arrangements of the 101st to 200th symbols of the pattern X in the IQ plane are as shown in FIG. 48B for the modulated signals A and B, respectively. At this time, it is assumed that the phase formed by the signal point and the I-axis is 45 degrees for the modulated signal A and 0 degrees for the modulated signal B.
It is assumed that the signal point arrangements of the 201st to 300th symbols of the pattern X in the IQ plane are as shown in FIG. 48C for the modulated signals A and B, respectively. At this time, it is assumed that the phase formed by the signal point and the I-axis is 45 degrees for the modulated signal A and 45 + 10 degrees for the modulated signal B.
In the present embodiment, the case where the 300 symbols are divided into three has been described, but when the 300 symbols are divided into m pieces, the phase composed of the signal point of the modulated signal A and the I axis is fixed at 45 degrees. Yes, the phase composed of the signal point of the modulated signal B and the I-axis changes as 45 degrees, 0 degrees, 45 + 10 degrees, 10 degrees, and so on.
In other words 1) The phase composed of the signal point of the modulated signal B and the I axis in the signal point arrangement of the 2n-1th change is 10n-10 degrees. 2) The phase composed of the signal point of the modulated signal B and the I axis in the signal point arrangement of the 2nth change is 45 + 10n degrees. And. However, n = 1, 2, ...
As described above, in the present embodiment, the method of arranging the signal points is changed in a predetermined block unit. As a result, the effect of interleaving is obtained by the method of arranging the signal points, so that the time diversity gain can be obtained. The reason for this will be described in the operation of the receiving device.
FIG. 49, which is shown by assigning the same reference numerals to the portions corresponding to FIG. 4, shows a configuration example of the transmission device according to the present embodiment. The coding unit 4802 receives the transmission digital signal 4801 as an input, encodes the transmission digital signal 4801 with, for example, a convolutional code, a turbo code, LDPC (Low Density Parity Check), etc., and outputs the coded digital signal 4803. Output.
The interleave unit 4804 receives the encoded digital signal 4803 and the frame configuration signal 324 as inputs, interleaves the encoded digital signal 4803 as shown in FIGS. 47A and 47C, and performs the interleaved digital signal. Output 4805.
The modulation unit 304 inputs the interleaved digital signal 4805 and the frame configuration signal 324, and outputs the transmission orthogonal baseband signal 305. The detailed configuration of the modulation unit 304 is as shown in FIG.
In FIG. 50, the mapping unit 4902 takes the interleaved digital signal 4901 and the frame configuration signal 4906 as inputs, performs QPSK modulation on the interleaved digital signal 4901 according to the signal point arrangement as shown in FIG. Outputs the band signal 4903.
The signal processing unit (rotation calculation unit) 4904 receives the orthogonal baseband signal 4903 and the frame configuration signal 4906 as inputs, and as described above, performs phase rotation so as to have different signal point arrangements in predetermined block units, and performs phase rotation. The later orthogonal baseband signal 4905 is output.
The coding unit 4807 and the interleaving unit 4809 of FIG. 49 perform the same operation as described above. The modulation unit 314 receives the interleaved digital signal as an input, performs QPSK modulation, and outputs a transmission orthogonal baseband signal 315. At this time, since the modulation unit 314 does not change the signal point arrangement for the modulation signal B as shown in FIG. 48A, unlike the modulation unit 304, the modulation unit 314 does not have the signal processing unit (rotation calculation unit) 4904 in FIG. You may.
FIG. 51 shows an example of the configuration of the receiving device according to the present embodiment, and the same reference numerals are given to those operating in the same manner as in FIG.
The MLD (Maximum Likelihood Detection) unit 523 obtains the branch metric by obtaining the Euclidean distance between the candidate signal point and the reception baseband signal, and obtains the soft judgment value 5001 of the modulation signal A and the soft judgment of the modulation signal B. Output the value 5002.
The deinterleave unit 5003 receives the soft determination value 5001 of the modulation signal A as an input, deinterleaves this, and outputs the soft determination value 5004 of the modulated signal A after the deinterleave. The decoding unit 5005 takes the soft judgment value 5004 of the modulated signal A after deinterleaving as an input, softly decodes the soft judgment value 5004, and outputs the received digital signal 5006 of the modulated signal A.
Similarly, the deinterleave unit 5007 receives the soft determination value 5002 of the modulated signal B as an input, deinterleaves this, and outputs the soft determination value 5008 of the modulated signal B after the deinterleave. The decoding unit 5009 takes the soft judgment value 5008 of the modulated signal B after deinterleaving as an input, softly decodes the soft judgment value 5008, and outputs the received digital signal 5010 of the modulated signal B.
By the way, let us consider the propagation environment of the outlook. At this time, the channel matrix in Eq. (1) is the channel element h of the direct wave component.<sub>11,d</sub>, h<sub>12, d</sub>, h<sub>21,d</sub>, h<sub>22,d</sub>And the channel element h of the scattered wave component<sub>11,s</sub>, h<sub>12,s</sub>, h<sub>21,s</sub>, h<sub>22,s</sub>It can be divided into the following and can be expressed as the following equation.<maths num="14"><img file="JP4445467B2_D0014.tif" /></maths>
It is known that when a direct wave channel element falls into a steady state, it exhibits completely different reception qualities depending on the state even if the received electric field strength is the same (for example, the document "MIMO system in rice fading". Analysis of "Institute of Electronics, Information and Communication Engineers, Institute of Electronics, Information and Communication Engineers, RCS2003-90, pp.1-6, July 2003). In particular, in a line-of-sight environment where direct waves predominate, there is a possibility of a steady state in which the effect of different interleave patterns between modulated signals does not appear sufficiently. In such a state, it is considered that good error rate characteristics cannot be obtained even if the received electric field strength is sufficient. This is because even if the received electric field strength is sufficient, the reception quality may deteriorate depending on the state of the direct wave matrix of Eq. (14).
In the present embodiment, since the method of arranging the signal points of at least one modulated signal is changed, the above-mentioned deterioration of reception quality can be improved. In particular, it is suitable for making a soft determination in a receiving device using a convolutional code or the like. The device configuration and operation are as described above. In the following, the reason why the reception quality is improved when the above configuration is adopted will be described in detail.
In FIGS. 52A and 52B, reference numeral 5101 is a signal point when the combined signal of the modulated signals A and B is received, and when both the modulated signals A and B are QPSK as shown in FIGS. 48A to 48C, FIG. There are 16 candidate signal points as shown in 52A and 52B. In FIGS. 52A and 52B, reference numeral 5102 indicates a virtual signal point when only the modulated signal A is received. In reality, since the modulated signals A and B are transmitted at the same time, the four points of 5102 do not become candidate signal points.
Here, when the modulated signal as shown in FIG. 48A is transmitted, it is assumed that the receiving device has the signal point arrangement as shown in FIG. 52A. At this time, paying attention to the minimum Euclidean distance, there is a very small place.
In an environment dominated by direct waves, if the modulation signal A and the modulation signal B are transmitted in the state shown in Fig. 48A, they will continue to be received in this state, and if soft judgment decoding is performed in this state, good quality data will be obtained. I can't get it.
In order to avoid this, in the present embodiment, for example, the modulation signal B is rotated by 45 degrees with respect to the arrangement of FIG. 48A as shown in FIG. 48B, and with respect to the arrangement of FIG. 48A as shown in FIG. 48C. Rotate 10 degrees. Then, for example, when transmitting as shown in FIG. 48B, the received signal points are arranged as shown in FIG. 52B, the minimum Euclidean distance becomes large, and the reception quality can be improved. In this way, when various phase rotations are applied to the modulated signal B, various Euclidean distances are obtained in an environment dominated by direct waves, so that an effect similar to the diversity effect can be obtained. Thereby, the quality of the received data can be improved.
As described above, in the present embodiment, the time diversity effect can be obtained and the error rate characteristic is improved by forming at least one modulated signal by changing the way of arranging the signal points in the time direction. You will be able to obtain received data.
In addition, by changing the method of arranging the signal points for each block of interleaving, it is possible to prevent the Euclidean distance between the candidate signal point and the receiving point from becoming extremely small on the receiving side due to the synergistic effect with interleaving. , Received data with further improved error rate characteristics can be obtained.
The angle at which the signal point arrangement of the modulated signal B is rotated is not limited to that described above. However, even if the rotation angle is configured only with the rotation angles of 90 degrees, 180 degrees, and 270 degrees, the effect cannot be obtained because the candidate signal point arrangement of the received signal does not change. The generality is established by configuring the rotation angle from 0 degrees to 45 degrees or from -45 degrees to 0 degrees, and if it is defined within this range, the configuration of the rotation calculation unit 4904 of the transmitter 4800 and the MLD unit 523 of the receiver 500. Can be simplified.
Further, in the above description, only the modulation signal B is rotated, but the same can be performed by rotating the modulation signal A. However, rotating both modulated signals or rotating only one does not significantly change the effect of improving reception quality. Therefore, considering simplifying the configuration of the rotation calculation unit 4904 of the transmission device 4800 and the MLD unit 523 of the reception device 5000, it is better to rotate only one of the modulated signals.
Next, a transmission method different from that described above will be described.
As shown in FIGS. 53A and 53B, the modulated signal B has a signal point arrangement at time T, while the time T + i has a θ with respect to the signal point arrangement at time T.<sub>i</sub>Rotate degrees. Incidentally, here, for the modulation signal A, a device that does not give rotation is considered as an example. In FIGS. 53A and 53B, the relationship between the signal point arrangement at time i and the signal point arrangement at time i + 1 is shown in the modulated signal B, and θ<sub>i</sub>-θ<sub>i-1</sub>= 10 degrees.
By transmitting in this way, as described above, in an environment where direct waves dominate, the Euclidean distance between the received signal point and the candidate signal point takes various values, so an effect similar to the diversity effect can be obtained. Can be done. Thereby, the error rate characteristic of the received data can be improved.
Further, as in the example given here, the relationship between the signal point arrangement at time i and the signal point arrangement at time i + 1 is θ.<sub>i</sub>-θ<sub>i-1</sub>If the fixed value of = 10 degrees is set, the calculation of the rotation calculation unit 4904 of the transmission device 4800 and the MLD523 of the reception device 5000 can be simplified.
Where θ<sub>i</sub>-θ<sub>i-1</sub>Regarding 0, 90, 180, and 270 degrees, the positional relationship of the candidate signal points in the MLD523 of the receiver 5000 does not change between time i and time i + 1, and the received signal point and the candidate signal point There is no change in the relationship between Euclidean distances. Then, the receiving device 5000 is not suitable for the rotation angle because it is difficult to obtain the diversity effect and the effect of improving the error rate of data is reduced. Thinking in the same way, θ<sub>i</sub>-θ<sub>i-1</sub>Even when is set to 45, 105, 225, and 315 degrees, it is difficult to obtain the diversity effect, so it is an inappropriate value.
By the way, θ<sub>i</sub>-θ<sub>i-1</sub>When is 0, 90, 180, 270 degrees, the positional relationship of the candidate signal points in the MLD of the receiving device is one type, but θ<sub>i</sub>-θ<sub>i-1</sub>When the temperature is 45, 105, 225, or 315 degrees, there are two types, and it is difficult to obtain the diversity effect at this time as well. That is, even if the conventional techniques QPSK and π / 4 shift QPSK are used, a very large diversity effect cannot be obtained. However, this does not mean that there is no diversity effect at all.
As an appropriate value, it is desirable to design the candidate signal points of the received signal to have a plurality of signal point arrangements (with a plurality of minimum Euclidean distances). For example, there are angles of 5 degrees (the angles that give candidate signal point arrangements for received signals similar to 5 degrees are 95, 185, 275, ...), And 90/5 = 18 possible signal point arrangements for received signals are given. There are 100, 190, 280, ... Angles that give candidate signal point arrangements for received signals similar to 10 degrees, and 90/10 = 9 possible received signal candidates. There are 105, 195, 285, and so on, which give the signal point arrangement of 15 degrees (the same as 15 degrees as the candidate signal point arrangement of the received signal), and 90/15 = 6 ways. The candidate signal point arrangement of the received signal of is given.) And so on. A more suitable value is a value that cannot be divided by 90 / x.
In the above description, the case where only the phase rotation is given has been described, but the method of arranging the signal points may be changed by switching the transmission power. It can also be used in combination with transmission power and phase rotation. FIGS. 54A and 54B show an example of arranging candidate signal points of the received signal when phase rotation and transmission power switching are used together. Even when used in combination, the relationship between Euclidean distances, particularly the minimum Euclidean distance, can be changed in the same manner as described above. As a result, the diversity effect can be obtained, and the error rate characteristic of the received data can be improved.
Further, a method is conceivable in which one modulated signal is coded and given phase rotation, and the other modulated signal is not coded. This realizes the trellis coding modulation proposed in the literature "Channel coding with multilevel / phase signals," IEEE Transaction on Information Theory, vol.IT-28, pp.55-67, January 1982 in a MIMO system. Equivalent to doing. In trellis coding modulation, coding is applied to constrain the transition of signal points, and this is designed to transition signal points that are distant from the Euclidean distance.
In order to obtain the same effect, it is important to give the rotation angle in the MIMO system. For example, when considering between two slots, rotating the phase changes the arrangement of signal points when received at time T and time T + 1, which results in different Euclidean distances. Therefore, it can be said that giving the phase rotation and performing the coding constrains the transition of the signal point as well as the trellis coding modulation.
In this embodiment, the case of performing spectral diffusion communication has been described, but the present invention is not limited to this, and the same can be applied to the case where there is no diffusion unit and back diffusion unit, that is, the single carrier method.
It can also be applied to a multi-carrier system such as OFDM. In this case, in addition to the method of forming a modulated signal whose phase is rotated in the time direction, the idea of changing the signal point arrangement in the time axis direction can be developed in the frequency axis direction. Specifically, different signal point arrangements (for example, rotation) can be given to each subcarrier (carrier). At this time, as an example of a simple configuration, a method of making the phase rotation unique for each subcarrier can be considered. That is, with respect to the signal point arrangement of the subcarrier 0, the subcarrier 1 is given a phase rotation of θ1, the subcarrier 2 is given a phase rotation of θ2, ..., And the subcarrier n is given a phase rotation of θn. As a result, the diversity effect can be obtained in the subcarrier direction (frequency direction), so that the error rate characteristic of the received data can be improved as in the case where the diversity effect is obtained in the time direction.
Further, in the present embodiment, in addition to the convolutional code, an LDPC, a turbo code, or the like can be applied in the same manner.
(5) Embodiment 5 In the present embodiment, it is proposed to receive feedback information indicating the reception state of the modulated signal from the communication partner and change the method of arranging the signal points based on the feedback information.
FIG. 55 shows a configuration example of the base station according to the present embodiment. In FIG. 55, the same reference numerals are given to those that operate in the same manner as in FIG. 49.
The base station 5400 receives the signal transmitted from the terminal by the receiving antenna 5401. The receiving device 5403 receives the received signal 5402 received by the receiving antenna 5401 as an input, demodulates the received signal 5402, and outputs the received digital signal 5504.
The signal point arrangement determination unit 5405 receives the received digital signal 5504 as an input, extracts feedback information from the received digital signal 5504, further determines the signal point arrangement from the feedback information, and outputs the signal point arrangement control signal 5406.
The modulation units 304 and 314 arrange the signal points based on the signal point arrangement control signal 5406.
Here, the base station 5400 notifies the terminal of information on how to arrange the signal points applied by the modulation units 304 and 314. Specifically, the base station 5400 includes in the transmission signal information about how to arrange the signal points performed at the time of modulation. The feedback information, the control method of the signal point arrangement, and the operation of the terminal will be described in detail later.
FIG. 56 shows a configuration example of the communication terminal according to the present embodiment. In FIG. 56, the same reference numerals are given to those that operate in the same manner as in FIG. 51.
The MLD unit 523 outputs the received signal point status information 5501 based on the transmission line estimation signals 508 and 518 of the modulation signal A and the transmission line estimation signals 510 and 520 of the modulation signal B. As the received signal point status information 5501, the minimum Euclidean distance, the status of the eigenvalues, the transmission line estimation signals of the modulated signals A and B, and the like are suitable, but the information is not limited to these. For example, a signal indicating the presence or absence of an error, such as ACK / NACK information, may be used as the received signal point status information 5501.
The feedback information generation unit 5502 receives the received signal point status information 5501 as an input, and outputs the feedback information 5503 based on the input. The feedback information generation unit 5502 may determine in advance how to arrange signal points in the base station 5400, and transmit this as feedback information 5503. That is, the communication terminal 5500 may determine how to arrange the signal points.
The transmission device 5505 receives the feedback information 5503 and the transmission digital signal 5504 as inputs, and forms and outputs the transmission signal 5506 by performing predetermined wireless processing on the feedback information 5503 and the transmission digital signal 5504. The transmission signal 5506 is output from the transmission antenna 5507.
Next, a control method of signal point arrangement will be described. For example, base station 5400 shall transmit modulation signals A and B as shown in FIG. 53A. Then, it is assumed that the communication terminal 5500 receives these modulated signals in the state as shown in FIG. 52A. This state can be understood from the information 5501 of the received signal point condition which is the information such as the minimum Euclidean distance and the eigenvalues output from the MLD unit 523, or the transmission line estimation signals of the modulated signals A and B. Then, the base station 5400 or the communication terminal 5500 determines how to arrange the signal points so that the minimum Euclidean distance becomes large as shown in FIG. 52B, and the base station 5400 performs the modulation process according to the determined signal point arrangement. For example, the base station 5400 switches the signal point arrangement method from FIG. 53A to FIG. 53B to perform modulation.
As described above, the feedback information indicating the reception state of the modulated signal is received from the communication partner, and the signal point arrangement is changed based on the feedback information, so that the signal point arrangement method is changed according to the reception state. Therefore, the minimum Euclidean distance can be further increased, and the error rate characteristic of the received data can be further improved. In particular, as in the fourth embodiment, a great effect can be obtained in an environment where direct waves are dominant.
In this embodiment, the case where spectral diffusion communication is performed has been described, but the present invention is not limited to this, and the same can be performed when there is no diffusion unit and back diffusion unit, that is, the single carrier method. it can. The same can be applied to a multi-carrier system such as OFDM.
Further, the change in the method of arranging the signal points is not limited to the phase rotation, and the same effect can be obtained by changing the transmission power as described in other embodiments. At this time, only the transmission power may be changed, or the transmission power and the phase rotation may be changed at the same time.
The present invention is also described, for example, in the document "Intrinsic Beam Space Division Multiplexing (E-SDM) Method in MIMO Channel", Electronic Information and Communication Society, Shingaku Gijutsu RCS 2002-53, May 2002. When applied to a MIMO system in which a transmission signal is multi-beamed and transmitted, the same effect as described above can be obtained.
FIG. 57 shows a schematic configuration of such a MIMO system. On the transmitting side, the modulation unit 5701 inputs a transmission data series and modulates the transmission data series to form a plurality of modulated signals. Here, as described in the above-described first to fifth embodiments, the modulation unit 5701 performs modulation processing on at least one modulated signal by changing the signal point arrangement method in the time direction or the frequency direction.
The channel analysis unit 5702 calculates the channel signature vectors of a plurality of transmissions for constructing the multiplexed channel based on the channel state information which is the estimation result of the propagation channel. The vector multiplexing unit 5703 multiplies each modulated signal by a different channel signature vector, synthesizes them, and sends the synthesized signal to the transmission array antenna 5704. As a result, a multi-beam signal is transmitted from the transmission array antenna 5704.
On the receiving side, the channel analysis unit 5711 calculates a plurality of receiving channel signature vectors for separating the multiplexed modulated signal based on the channel state information which is the estimation result of the propagation channel. The multiplex signal separation unit 5713 inputs the received signal of the receiving array antenna 5712 and multiplies each received signal by a different channel signature vector to convert a signal in which a plurality of modulated signals are multiplexed into a plurality of received modulated signals. To separate. The signal processing unit 5714 obtains received data by demodulating and decoding the separated reception modulated signal.
The present invention is not limited to the above embodiments 1 to 5, and can be modified in various ways. For example, in the above-described embodiment, the case where the present invention is implemented mainly by hardware has been described, but the present invention is not limited to this, and it is also possible to implement the present invention by software.
For example, a program that executes the above-mentioned functions may be stored in ROM (Read Only Memory) in advance, and the program may be operated by a CPU (Central Processor Unit).
As described above, according to the present invention, it is possible to realize a communication device and a method capable of obtaining excellent reception quality while suppressing a decrease in data transmission efficiency.
This specification is based on Japanese Patent Application No. 2003-190683 filed on July 2, 2003 and Japanese Patent Application No. 2004-173224 filed on May 14, 2004. All the contents are included here.
The present invention can be widely applied to a wireless system that transmits different modulated signals from a plurality of antennas, and is suitable for application to, for example, an OFDM-MIMO communication system.
<figref num="1">FIG. 1A is a diagram showing an example of a frame configuration of a conventional transmission signal, and FIG. 1B is a diagram showing a relationship between a transmission antenna and a reception antenna.</figref><figref num="2">FIG. 2A is a diagram showing an example of a frame configuration of a modulated signal according to the first embodiment, and FIG. 2B is a diagram showing a relationship between a transmitting antenna and a receiving antenna.</figref><figref num="3">3A to 3C are diagrams showing an example of signal point arrangement in the first embodiment.</figref><figref num="4">A block diagram showing a configuration example of a transmission device according to the first embodiment.</figref><figref num="5">A block diagram showing a configuration example of a modulation unit according to the first embodiment.</figref><figref num="6">A block diagram showing a configuration example of a receiving device according to the first embodiment.</figref><figref num="7">Block diagram showing a configuration example of the demodulation unit according to the first embodiment</figref><figref num="8">Block diagram showing other configuration examples of the demodulator</figref><figref num="9">The figure which shows the frame configuration example in Embodiment 1.</figref><figref num="10">10A and 10B are diagrams showing a frame configuration example according to the first embodiment.</figref><figref num="11">11A to 11C are diagrams showing an example of signal point arrangement in the first embodiment.</figref><figref num="12">The figure which shows the structural example of the demodulation part in Embodiment 1.</figref><figref num="13">The figure which shows the frame structure example of the modulation signal in Embodiment 1.</figref><figref num="14">The figure which shows the reception state in Embodiment 1.</figref><figref num="15">The figure which shows the frame structure example of the modulation signal in Embodiment 2.</figref><figref num="16">The figure which shows the frame structure example of the modulation signal in Embodiment 2.</figref><figref num="17">The figure which shows the relationship of the transmission / reception antenna in Embodiment 2.</figref><figref num="18">A block diagram showing a configuration example of a transmission device according to the second embodiment.</figref><figref num="19">Block diagram showing a configuration example of the receiving device according to the second embodiment</figref><figref num="20">Block diagram showing a configuration example of the demodulation unit according to the second embodiment</figref><figref num="21">The figure which shows the frame structure example of the modulation signal in Embodiment 2.</figref><figref num="22">The figure which shows the frame structure example of the modulation signal in Embodiment 2.</figref><figref num="23">A block diagram showing a configuration example of a transmission device according to the second embodiment.</figref><figref num="24">Block diagram showing a configuration example of the demodulation unit according to the second embodiment</figref><figref num="25">The figure which shows the frame structure example of the modulation signal in Embodiment 2.</figref><figref num="26">The figure which shows the frame structure example of the modulation signal in Embodiment 2.</figref><figref num="27">A block diagram showing a configuration example of a transmission device according to the third embodiment.</figref><figref num="28">Block diagram showing a configuration example of the receiving device according to the third embodiment</figref><figref num="29">29A and 29B are diagrams showing a frame configuration example of the modulated signal according to the third embodiment.</figref><figref num="30">30A and 30B are diagrams showing a frame configuration example of the modulated signal according to the third embodiment.</figref><figref num="31">31A and 31B are diagrams showing a frame configuration example of the modulated signal according to the third embodiment.</figref><figref num="32">32A and 32B are diagrams showing a frame configuration example of the modulated signal according to the third embodiment.</figref><figref num="33">33A and 33B are diagrams showing a frame configuration example of the modulated signal according to the third embodiment.</figref><figref num="34">34A and 34B are diagrams showing a frame configuration example of the modulated signal according to the third embodiment.</figref><figref num="35">35A and 35B are diagrams showing a frame configuration example of the modulated signal according to the third embodiment.</figref><figref num="36">36A and 36B are diagrams showing a frame configuration example of the modulated signal according to the third embodiment.</figref><figref num="37">37A and 37B are diagrams showing a frame configuration example of the modulated signal according to the third embodiment.</figref><figref num="38">38A and 38B are diagrams showing a frame configuration example of the modulated signal according to the third embodiment.</figref><figref num="39">39A to 39C are diagrams showing a frame configuration example of the modulated signal according to the third embodiment.</figref><figref num="40">40A to 40C are diagrams showing a frame configuration example of the modulated signal according to the third embodiment.</figref><figref num="41">41A to 41C are diagrams showing a frame configuration example of the modulated signal according to the third embodiment.</figref><figref num="42">42A to 42C are diagrams showing a frame configuration example of the modulated signal according to the third embodiment.</figref><figref num="43">43A to 43C are diagrams showing a frame configuration example of the modulated signal according to the third embodiment.</figref><figref num="44">44A to 44C are diagrams showing a frame configuration example of the modulated signal according to the third embodiment.</figref><figref num="45">45A to 45C are diagrams showing a frame configuration example of the modulated signal according to the third embodiment.</figref><figref num="46">46A to 46C are diagrams showing a frame configuration example of the modulated signal according to the third embodiment.</figref><figref num="47">47A and 47B are diagrams used to explain the interleave in the fourth embodiment.</figref><figref num="48">48A to 48C are diagrams showing an example of signal point arrangement in the fourth embodiment.</figref><figref num="49">Block diagram showing a configuration example of the transmitter of the fourth embodiment</figref><figref num="50">Block diagram showing a configuration example of the modulation unit of the fourth embodiment</figref><figref num="51">Block diagram showing a configuration example of the receiving device of the fourth embodiment</figref><figref num="52">FIG. 52A is a diagram showing the state of the received signal point where the minimum Euclidean distance is small and the reception quality is poor, and FIG. 52B is a diagram showing the state of the received signal point where the minimum Euclidean distance is large and the reception quality is good.</figref><figref num="53">53A and 53B are diagrams showing an example of signal point arrangement in the fourth embodiment.</figref><figref num="54">FIG. 54A is a diagram showing the state of the received signal point where the minimum Euclidean distance is small and the reception quality is poor, and FIG. 54B is a diagram showing the state of the received signal point where the minimum Euclidean distance is large and the reception quality is good.</figref><figref num="55">Block diagram showing a configuration example of the base station of the fifth embodiment</figref><figref num="56">Block diagram showing a configuration example of the communication terminal of the fifth embodiment</figref><figref num="57">A block diagram showing a multi-beam MIMO system as an application example of the present invention.</figref>
Every citation, both waysCites: the store holds 2 of 3
| Document | Relation | Office |
|---|---|---|
| WO03049397A1 | Cites | World Intellectual Property Organization (WIPO) |
| JP2004023727A | Cites | Japan |
| 久保 博嗣・東中 雅嗣・岡崎 彰浩・村上 圭司,送信アンテナ毎に異なった差動マッピングを行うMIMO伝送方式に関する検討,電子情報通信学会技術研究報告,2003年11月14日,103(457) pp.145-150 | Non-patent | – |
40 members in 5 offices
Priority claims14
| Document | Office | Kind | Date |
|---|---|---|---|
| 2003190683 | Japan | A | |
| 2003190683 | Japan | A | |
| 2003190683 | Japan | – | |
| 2004173224 | Japan | A | |
| 2004173224 | Japan | A | |
| 2004173224 | Japan | – | |
| 2004009774 | Japan | W | |
| 2004009774 | Japan | W | |
| 20032003190683 | – | – | – |
| 20042004173224 | – | – | – |
| 2004009774 | – | – | – |
| JP20030190683 | – | – | – |
| JP20040173224 | – | – | – |
| WO2004JP09774 | – | – | – |
Members40
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| WO2005004367B1 | World Intellectual Property Organization (WIPO) | B1 | |
| EP1633067A2 | European Patent Office (EPO) | A2 | |
| US2006160496A1 | United States of America | A1 | |
| CN1846383A | China | A | |
| JPWO2005004367A1 | Japan | A1 | |
| JP2010045864A | Japan | A | |
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| CN1846383B | China | B | |
| US2011170634A1 | United States of America | A1 | |
| EP1633067A4 | European Patent Office (EPO) | A4 | |
| JP4975799B2 | Japan | B2 | |
| US8259837B2 | United States of America | B2 | |
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Numbers
- Publication
- 4445467
- Publication, DOCDB
- 4445467
- Publication, EPODOC
- JP4445467B
- Application
- 2005511425
- Application, DOCDB
- 2005511425
- Application, EPODOC
- JP20050511425
Titles2
- Japanese
- 通信装置および通信方法
- English
- Communication device and communication method
Classification
- CPC, 12
- H04B7/0417
- H04L27/0008
- H04B7/0669
- H04L1/0006
- H04L1/0026
- H04L1/06
- H04L1/0618
- H04L1/08
- H04L27/3405
- H04W52/42
- H04L5/0046
- H04B7/0413
- IPC, 13
- H04J99 00
- H04L27 36
- H04J11 00
- H04B1 707
- H04B7 02
- H04B7 06
- H04B7 005
- H04L
- H04L1 00
- H04L27 18
- H04L27 34
- H04W16 28
- H04W72 04