Communication control device, communication control method, program, terminal device, and communication control system
17 claims: 4 independent, 13 dependent
- 1無線通信ネットワーク上で時分割複信方式に従って端末装置により行われる通信を制御する通信装置であって、 複数のサブフレームを含むフレームの各々について、サブフレーム単位のリンク方向を表すリンク方向コンフィギュレーションを設定する、ように構成される回路を備え、 前記回路は、 第1の端末グループのために第1のリンク方向コンフィギュレーションを設定し、第2の端末グループのために第2のリンク方向コンフィギュレーションを設定し、 第1の周期で前記第1の端末グループに属する端末装置へ前記第1のリンク方向コンフィギュレーションをシグナリングし、 前記第1の周期よりも短い第2の周期で前記第2の端末グループに属する端末装置へ前記第2のリンク方向コンフィギュレーションをシグナリングする、 ように構成され、 前記第2の周期は、10ミリ秒の整数倍であり、 前記回路は、前記第2のリンク方向コンフィギュレーションとして、前記第1のリンク方向コンフィギュレーションのダウンリンクサブフレームをダウンリンクサブフレームとして維持しつつ、前記第1のリンク方向コンフィギュレーションのアップリンクサブフレームをダウンリンクサブフレームに置き換えることにより導かれるコンフィギュレーションを設定する、ように構成される、 通信装置。
- 2前記第2の周期は、40ミリ秒である、請求項1に記載の通信装置。
- 3前記回路は、前記第1のリンク方向コンフィギュレーションとして、アップリンク率のより高いコンフィギュレーションを設定する、ように構成される、請求項1に記載の通信装置。
- 4前記回路は、前記第2のリンク方向コンフィギュレーションにおいて前記ダウンリンクサブフレームに置き換えられている前記アップリンクサブフレームについて、前記第1の端末グループに属する端末装置にアップリンク送信を許可しない、ように構成される、請求項3に記載の通信装置。
- 5前記回路は、前記第1の端末グループに属する端末装置へのダウンリンク送信を、当該ダウンリンク送信に関連付けられるACK/NACK送信のためのサブフレームが前記第2のリンク方向コンフィギュレーションにおいて前記アップリンクサブフレームとして指定されているサブフレームにのみスケジューリングする、ように構成される、請求項4に記載の通信装置。
- 6前記回路は、 コンフィギュレーション候補ごとにアップリンク送信のタイミングと対応するアップリンク許可の送信タイミングとを関連付けるテーブルを記憶し、 前記第1の端末グループに属する端末装置のアップリンク送信に対応する前記アップリンク許可を送信するためのサブフレームを、前記テーブル内の前記第1のリンク方向コンフィギュレーションについてのエントリを参照することにより決定する、 ように構成される、請求項4に記載の通信装置。
- 7前記回路は、 コンフィギュレーション候補ごとにアップリンク送信のタイミングと対応するACK/NACKの送信タイミングとを関連付けるテーブルを記憶し、 前記第1の端末グループに属する端末装置のアップリンク送信に対して前記ACK/NACKを送信するためのサブフレームを、前記テーブル内の前記第1のリンク方向コンフィギュレーションについてのエントリを参照することにより決定する、 ように構成される、請求項4に記載の通信装置。
- 8前記回路は、 前記第1のリンク方向コンフィギュレーションとしてダウンリンク率のより高いコンフィギュレーションを設定すると共に、当該第1のリンク方向コンフィギュレーションのダウンリンクサブフレームの少なくとも1つをMBSFN(MBMS Single Frequency Network)サブフレームに設定し、 前記第2のリンク方向コンフィギュレーションとして、前記第1のリンク方向コンフィギュレーションの前記MBSFNサブフレームをアップリンクサブフレームに置き換えることにより導かれるコンフィギュレーションを設定する、 ように構成される、請求項1に記載の通信装置。
- 9前記回路は、 前記第1のリンク方向コンフィギュレーションとは異なる前記第2のリンク方向コンフィギュレーションが設定可能であるダイナミックモード、及び前記第1のリンク方向コンフィギュレーションと同じ前記第2のリンク方向コンフィギュレーションが設定されるセミスタティックモードの双方で動作可能であり、 前記ダイナミックモードでの動作中に前記第1の端末グループのためにバッファリングされているトラフィック量が第1の閾値を上回ると、前記セミスタティックモードへ遷移する、 ように構成される、請求項1に記載の通信装置。
- 10前記回路は、前記セミスタティックモードでの動作中に前記第1の端末グループのためにバッファリングされているトラフィック量が第2の閾値を下回ると、前記ダイナミックモードへ遷移する、ように構成される、請求項9に記載の通信装置。
- 11前記回路は、アップリンクトラフィックとダウンリンクトラフィックとの間のトラフィック量の比に基づいて、各フレームに設定すべき前記第1のリンク方向コンフィギュレーション及び前記第2のリンク方向コンフィギュレーションを選択する、ように構成される、請求項1に記載の通信装置。
- 12前記第2の端末グループに属する端末装置は、前記第1の周期でリンク方向コンフィギュレーションが更新される第1の動作モード及び前記第2の周期でリンク方向コンフィギュレーションが更新される第2の動作モードの双方で動作可能であり、 前記回路は、前記トラフィック量の比が所定の条件を満たす場合に、前記第2の端末グループに属する端末装置へ前記第2の動作モードへの切替えを指示する、ように構成される、 請求項11に記載の通信装置。
- 13前記通信装置は、基地局であり、 前記基地局は、前記第2のリンク方向コンフィギュレーションに従って無線信号を送信し及び受信する、ように構成される、 請求項1に記載の通信装置。
- 14前記通信装置は、基地局を介して前記1つ以上の端末装置と通信する制御ノードである、請求項1に記載の通信装置。
- 15無線通信ネットワーク上で時分割複信方式に従って端末装置により行われる通信を制御する通信装置により実行される通信方法であって、 前記通信装置は、複数のサブフレームを含むフレームの各々について、サブフレーム単位のリンク方向を表すリンク方向コンフィギュレーションを設定するように構成され、 前記通信方法は、 第1の端末グループのために第1のリンク方向コンフィギュレーションを設定することと、 第2の端末グループのために第2のリンク方向コンフィギュレーションを設定することと、 第1の周期で前記第1の端末グループに属する端末装置へ前記第1のリンク方向コンフィギュレーションをシグナリングすることと、 前記第1の周期よりも短い第2の周期で前記第2の端末グループに属する端末装置へ前記第2のリンク方向コンフィギュレーションをシグナリングすることと、 を含み、 前記第2の周期は、10ミリ秒の整数倍であり、 前記第2のリンク方向コンフィギュレーションとして、前記第1のリンク方向コンフィギュレーションのダウンリンクサブフレームをダウンリンクサブフレームとして維持しつつ、前記第1のリンク方向コンフィギュレーションのアップリンクサブフレームをダウンリンクサブフレームに置き換えることにより導かれるコンフィギュレーションが設定される、 通信方法。
- 16無線通信ネットワーク上で時分割複信方式に従って端末装置により行われる通信を制御する通信装置のコンピュータに、複数のサブフレームを含むフレームの各々について、サブフレーム単位のリンク方向を表すリンク方向コンフィギュレーションを設定させるプログラムであって、 前記プログラムは、 第1の端末グループのために第1のリンク方向コンフィギュレーションを設定することと、 第2の端末グループのために第2のリンク方向コンフィギュレーションを設定することと、 第1の周期で前記第1の端末グループに属する端末装置へ前記第1のリンク方向コンフィギュレーションをシグナリングすることと、 前記第1の周期よりも短い第2の周期で前記第2の端末グループに属する端末装置へ前記第2のリンク方向コンフィギュレーションをシグナリングすることと、 を前記コンピュータに行わせ、 前記第2の周期は、10ミリ秒の整数倍であり、 前記第2のリンク方向コンフィギュレーションとして、前記第1のリンク方向コンフィギュレーションのダウンリンクサブフレームをダウンリンクサブフレームとして維持しつつ、前記第1のリンク方向コンフィギュレーションのアップリンクサブフレームをダウンリンクサブフレームに置き換えることにより導かれるコンフィギュレーションが設定される、 プログラム。
- 17無線通信ネットワーク上で時分割複信方式に従って基地局と通信する端末装置であって、 前記基地局からシグナリングされるリンク方向コンフィギュレーションに従い、複数のサブフレームを含むフレームの各々について、サブフレーム単位のリンク方向を設定する、ように構成される回路を備え、 前記回路は、第1の端末グループのために設定される第1のリンク方向コンフィギュレーションのシグナリング周期よりも短いシグナリング周期で、前記端末装置が属する第2の端末グループのために設定される第2のリンク方向コンフィギュレーションのシグナリングを受信する、ように構成され、 前記第2のリンク方向コンフィギュレーションのシグナリング周期は、10ミリ秒の整数倍であり、 前記第2のリンク方向コンフィギュレーションは、前記第1のリンク方向コンフィギュレーションのダウンリンクサブフレームをダウンリンクサブフレームとして維持しつつ、前記第1のリンク方向コンフィギュレーションのアップリンクサブフレームをダウンリンクサブフレームに置き換えることにより導かれる、 端末装置。
Independent claims17
132 paragraphs, as filed
0001The present disclosure relates to communication devices, communication methods, programs and terminal devices.
0002In recent years, a high-speed cellular wireless communication system called the LTE (Long Term Evolution) system has been put into practical use. The LTE system is classified into the FD-LTE system and the TD-LTE system based on the difference in the duplex system. The FD-LTE system adopts Frequency Division Duplex (FDD) as the duplex system, and the uplink and downlink are operated on different frequency bands. The TD-LTE system adopts Time Division Duplex (TDD) as the duplex system, and the uplink and downlink are operated on the same frequency band. Both the FD-LTE system and the TD-LTE system use a frame format in which one radio frame (having a time length of 10 msec) is composed of 10 subframes each having a time length of 1 msec. In the FD-LTE method, the link direction does not change with time in the same frequency band, whereas in the TD-LTE method, the link direction can change in subframe units.
0003In the TD-LTE system, a set of link directions for each subframe for each radio frame (that is, a combination of link directions of 10 subframes) is called a link direction configuration (or UL-DL configuration). According to Non-Patent Document 1 below, seven types of link direction configurations from Configuration 0 to Configuration 6 are defined. The radio base station (eNB in the LTE system) signals the link direction configuration set for each radio frame to the terminal device (UE in the LTE system) by broadcasting it in SIB1 (System Information Block Type 1). To do. According to the current standard specifications, the update cycle of the link direction configuration using SIB1 is 640 msec. Non-Patent Document 2 below proposes to shorten this cycle to 320 msec.
<p num="0004"><nplcit num="1"><text>"3GPP TS 36.211 V10.0.0 (2010-12)", December 22, 2010</text></nplcit><nplcit num="2"><text>"Semi-static reconfiguration of TDD UL-DL configuration", R1-122266, 3GPP TSG RAN WG1 Meeting # 69, Prague, Czech Republic, May 21-25, 2012</text></nplcit></p>
<p num="0005"> However, the signaling cycle of 640 msec or 320 msec is not sufficient in the modern wireless communication environment in which the ratio between uplink traffic and downlink traffic (UL-DL traffic ratio) fluctuates sharply. If the link-direction configuration update does not keep up with fluctuations in the UL-DL traffic ratio, the amount of buffered traffic will increase, which can lead to problems of reduced resource efficiency and reduced throughput.</p><p num="0006"> Therefore, it is desirable to provide a mechanism that can more quickly follow the link direction configuration of the terminal device to the fluctuation of the UL-DL traffic ratio.</p>
<p num="0007"> According to the present disclosure, it is a communication device that controls communication performed by a terminal device according to a time-division duplex system on a wireless communication network, and for each frame including a plurality of subframes, the link direction of each subframe is determined. It comprises a circuit configured to set the link direction configuration to represent, said circuit sets the first link direction configuration for the first terminal group and the second for the second terminal group. The second link-direction configuration is set, the first link-direction configuration is signaled to the terminal devices belonging to the first terminal group in the first cycle, and the second cycle is shorter than the first cycle. The second link-direction configuration is signaled to a terminal device belonging to the second terminal group, the second period is an integral multiple of 10 milliseconds, and the circuit is the same. As the second link direction configuration, the uplink subframe of the first link direction configuration is maintained as the downlink subframe, while the uplink subframe of the first link direction configuration is the downlink subframe. A communication device is provided that is configured to configure a configuration that is guided by replacing it with.</p><p num="0008"> Further, according to the present disclosure, it is a communication method executed by a communication device that controls communication performed by a terminal device according to a time-division duplex system on a wireless communication network, and the communication device includes a plurality of subframes. For each of the included frames, it is configured to set a link direction configuration that represents the link direction for each subframe, and the communication method sets the first link direction configuration for the first terminal group. And to set the second link-direction configuration for the second terminal group, and to signal the first link-direction configuration to the terminal devices belonging to the first terminal group in the first cycle. The second cycle includes signaling the second link-direction configuration to a terminal device belonging to the second terminal group in a second cycle shorter than the first cycle. , An integral multiple of 10 milliseconds, and as the second link-direction configuration, the first link-direction configuration while maintaining the downlink subframe of the first link-direction configuration as a downlink subframe. A communication method is provided in which the configuration derived by replacing the uplink subframe of the operation with the downlink subframe is set.</p><p num="0009"> Further, according to the present disclosure, the computer of the communication device that controls the communication performed by the terminal device according to the time division duplex method on the wireless communication network is linked to the computer of the communication device in units of subframes for each of the frames including a plurality of subframes. A program that sets the link-direction configuration that represents the direction, the program that sets the first link-direction configuration for the first terminal group and the second for the second terminal group. Setting the link direction configuration of the above, signaling the first link direction configuration to the terminal devices belonging to the first terminal group in the first cycle, and a second period shorter than the first cycle. The computer is made to signal the second link direction configuration to the terminal devices belonging to the second terminal group in two cycles, and the second cycle is an integral multiple of 10 milliseconds. Yes, as the second link-direction configuration, the uplink subframe of the first link-direction configuration is maintained as a downlink subframe, while the uplink subframe of the first link-direction configuration is down. A program is provided that sets the configuration guided by replacing it with a linked subframe.</p><p num="0010"> Further, according to the present disclosure, a terminal device that communicates with a base station according to a time-division duplex method on a wireless communication network, and includes a plurality of subframes according to a link direction configuration signaled from the base station. Each of the circuits comprises a circuit configured to set the link direction in subframe units, which is more than the signaling cycle of the first link direction configuration set for the first terminal group. The signaling cycle of the second link-direction configuration is configured to receive the signaling of the second link-direction configuration configured for the second terminal group to which the terminal device belongs in a short signaling cycle. Is an integral multiple of 10 milliseconds, and the second link direction configuration maintains the downlink subframe of the first link direction configuration as a downlink subframe while maintaining the first link direction. A terminal device is provided that is derived by replacing the uplink subframe of the configuration with a downlink subframe.</p>
<p num="0011"> According to the technique according to the present disclosure, the link direction configuration of the terminal device can be made to follow the fluctuation of the UL-DL traffic ratio more quickly.</p>
0012<figref num="1">It is explanatory drawing for demonstrating an example of the link direction configuration in TD-LTE.</figref><figref num="2">It is explanatory drawing which shows the list of the link direction configuration which can be set in TD-LTE.</figref><figref num="3A">It is 1st explanatory diagram for demonstrating the setting of the link direction configuration according to the buffer status.</figref><figref num="3B">It is a 2nd explanatory diagram for demonstrating the setting of the link direction configuration according to the buffer status.</figref><figref num="4">It is explanatory drawing for demonstrating the signaling of the link direction configuration using a new message.</figref><figref num="5A">It is explanatory drawing which shows the 1st example of the subframe including CRS (Cell-specific Reference Symbol).</figref><figref num="5B">It is explanatory drawing which shows the 2nd example of the subframe including CRS.</figref><figref num="6">It is explanatory drawing for demonstrating the 1st method for solving the influence of the difference of a link direction.</figref><figref num="7">It is explanatory drawing for demonstrating the combination of the configuration for legacy and for dynamic TDD in the 1st method.</figref><figref num="8">It is explanatory drawing for demonstrating an example of the link direction configuration set in 1st method along the time axis.</figref><figref num="9">It is explanatory drawing for demonstrating the 2nd method for solving the influence of the difference of a link direction.</figref><figref num="10">It is explanatory drawing for demonstrating the combination of the configuration for legacy and dynamic TDD in the 2nd method.</figref><figref num="11">It is explanatory drawing for demonstrating an example of the link direction configuration set in the 2nd method along the time axis.</figref><figref num="12">It is explanatory drawing for demonstrating an example of the control information area to which a dynamic configuration message is transmitted.</figref><figref num="13">It is explanatory drawing for demonstrating the first example of the influence of the difference in the link direction with respect to the control signaling in which a legacy terminal is involved.</figref><figref num="14">It is explanatory drawing for demonstrating the 2nd example of the influence of the difference in the link direction with respect to the control signaling in which a legacy terminal is involved.</figref><figref num="15">It is explanatory drawing for demonstrating the 3rd example of the influence of the difference in the link direction about the control signaling in which a legacy terminal is involved.</figref><figref num="16">It is explanatory drawing which shows an example of the structure of the communication control system which concerns on one Embodiment.</figref><figref num="17">It is a block diagram which shows an example of the configuration of a legacy terminal.</figref><figref num="18">It is a block diagram which shows an example of the structure of the dynamic TDD terminal which concerns on one Embodiment.</figref><figref num="19">It is a block diagram which shows an example of the structure of the communication control device which concerns on one Embodiment.</figref><figref num="20">It is a state transition diagram which shows an example of the transition between setting modes in the 1st method.</figref><figref num="21">It is a state transition diagram which shows an example of the transition between setting modes in the 2nd method.</figref><figref num="22">It is a flowchart which shows an example of the flow of communication processing executed by a dynamic TDD terminal.</figref><figref num="23A">This is the first part of the flowchart showing an example of the flow of communication control processing executed according to the first method.</figref><figref num="23B">This is the second part of the flowchart showing an example of the flow of communication control processing executed according to the first method.</figref><figref num="24A">This is the first part of the flowchart showing an example of the flow of communication control processing executed according to the second method.</figref><figref num="24B">This is the second part of the flowchart showing an example of the flow of communication control processing executed according to the second method.</figref>
0013Preferred embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings. In the present specification and the drawings, components having substantially the same functional configuration are designated by the same reference numerals, so that duplicate description will be omitted.
0014In addition, explanations will be given in the following order. 1. Overview 1-1. Link direction configuration settings 1-2. Link direction configuration signaling 1-3. Basic Principle 2. Communication control system configuration 2-1. System overview 2-2. Configuration example of legacy terminal 2-3. Configuration example of dynamic TDD terminal 2-4. Configuration example of communication control device 2-5. Transition of setting mode 3. Example of processing flow 3-1. Processing on the terminal side 3-2. Processing on the network side 4. Summary
0015<1. Overview> [1-1. Link Direction Configuration Settings] FIG. 1 is an explanatory diagram for explaining an example of a link direction configuration in TD-LTE. With reference to FIG. 1, the frame format of the wireless frame adopted in the LTE system is shown. One radio frame (radio) frame) contains 10 subframes (# 0 ~ # 9). The time length of each subframe is 1 msec, and the time length of one radio frame is 10 msec. The link direction is set in subframe units. In the example of FIG. 1, the link direction of the subframe labeled "D" is the downlink, and the subframe is referred to as the downlink subframe. The link direction of the subframe labeled "U" is the uplink, and the subframe is called the uplink subframe. The subframe labeled "S" is a special subframe unique to TD-LTE. As illustrated in FIG. 1, the downlink signal transmitted from the base station (eNB) reaches the terminal device (UE) together with the delay dT. The terminal device transmits the uplink signal prior to the timing of the uplink subframe of the base station, taking into account the delay dT of the uplink signal arriving at the base station. The special subframe is inserted at the timing of switching from the downlink subframe to the uplink subframe, and serves as a buffer period for preventing the timings of receiving the downlink signal and transmitting the uplink signal at the terminal device from overlapping. Has a role. The special subframe includes a downlink pilot time slot in which the UE receives the downlink signal, a Guard Period, and an uplink pilot time slot in which the UE transmits the uplink signal. In addition, downlink data can be transmitted from the base station to the terminal device even in the special subframe. In that sense, special subframes can also be considered as a type of downlink subframe.
0016FIG. 2 shows a list of seven types of link direction configurations that can be set in TD-LTE as defined in Non-Patent Document 1. As can be seen from FIG. 2, the 0th subframe (# 0) and the 5th subframe (# 5) are set to the downlink subframe in both configurations. The first subframe (# 1) is set as a special subframe in any configuration. The second subframe (# 2) is set to the uplink subframe in both configurations. The remaining subframe settings vary from configuration to configuration.
0017At the right end of FIG. 2, the composition ratio (UL-DL composition ratio) of the number of uplink subframes and the number of Dowlink subframes is shown. In Configuration0, the number of uplink subframes is 6, the number of downlink subframes is 2, and the UL-DL composition ratio is 6: 2. In Configuration1, the number of uplink subframes is 4, the number of downlink subframes is 4, and the UL-DL composition ratio is 4: 4. In Configuration2, the number of uplink subframes is 2, the number of downlink subframes is 6, and the UL-DL composition ratio is 2: 6. In Configuration3, the number of uplink subframes is 3, the number of downlink subframes is 6, and the UL-DL composition ratio is 3: 6. In Configuration4, the number of uplink subframes is 2, the number of downlink subframes is 7, and the UL-DL composition ratio is 2: 7. In Configuration5, the number of uplink subframes is 1, the number of downlink subframes is 8, and the UL-DL composition ratio is 1: 8. In Configuration6, the number of uplink subframes is 5, the number of downlink subframes is 3, and the UL-DL composition ratio is 5: 3.
0018A wireless communication system operating according to the TD-LTE system can determine which of the seven link-direction configurations should be used based on the UL-DL traffic ratio. Generally, the uplink signal is buffered by the uplink buffer of the terminal device before transmission is allowed. On the other hand, the downlink signal is P-GW (PDN) in the core network before the transmission is scheduled. Buffered by Gateway). A buffer overflow occurs when the amount of traffic waiting in the buffer exceeds the buffer capacity. Also, traffic buffered for more than a predetermined period of time may be discarded as a timeout. Therefore, the terminal device periodically transmits a buffer status report indicating the amount of uplink traffic waiting for the buffer to the base station. The P-GW provides buffer signaling that indicates the amount of downlink traffic waiting in the buffer. This allows the scheduler in the base station or other control node to calculate the UL-DL traffic ratio for each cell. For example, in the example of Figure 3A, there is more uplink traffic waiting in the buffer than downlink traffic waiting in the buffer. In this case, it is possible to reduce the uplink traffic waiting for the buffer by setting the link direction configuration having a high uplink rate. On the other hand, in the example of FIG. 3B, there is more downlink traffic waiting in the buffer than uplink traffic waiting in the buffer. In this case, it is possible to reduce the downlink traffic waiting for the buffer by setting the link direction configuration having a high downlink rate.
0019[1-2. Link Direction Configuration Signaling] The link-direction configuration set by the base station or other control node is signaled by broadcasting from the base station to the terminal device using SIB1. The update cycle of SIB1 in the current standard specifications is 640 msec. According to Non-Patent Document 2 above, the update cycle of the link direction configuration using SIB1 can be shortened to 320 msec. SIB1 is one of various types of SIB (System Information Block) mapped to DL-SCH (Downlink Shared Channel). The message that carries the SIB is called an SI (System Information) message. The shortest transmission cycle of SI messages is 80 msec. Therefore, as long as the link direction configuration is signaled by the SI message, the update cycle of the link direction configuration is 80 msec at the shortest.
0020In recent years, wireless communication traffic has increased dramatically. UL-DL traffic ratios fluctuate frequently. Therefore, the signaling cycle of the link direction configuration in the existing method is not sufficient to keep up with the fluctuation of the UL-DL traffic ratio. If the link-direction configuration update does not keep up with fluctuations in the UL-DL traffic ratio, the amount of traffic waiting in the buffer will increase, causing reduced resource efficiency and reduced throughput. If the signaling overhead is not taken into account, the ideal update period for the link-direction configuration is 10 msec, since the time length of one radio frame is 10 msec. However, if the signaling mechanism of the link direction configuration is completely changed from the existing method, the existing terminal device cannot acquire the link direction configuration and becomes inoperable. Therefore, in the technology according to the present disclosure, it is possible to quickly follow the link direction configuration with respect to the fluctuation of the UL-DL traffic ratio while minimizing the impact on the existing terminal device by the new mechanism as described below. And.
0021[1-3. Basic Principle] (1) New signaling message In the technique according to the present disclosure, a new message different from the SI message for signaling the link direction configuration to the terminal device is introduced in a shorter cycle than the existing method. The new message introduced is referred to herein as a dynamic configuration message. A terminal device that receives only SI messages for setting the link direction configuration is called a legacy terminal (legacy UE). On the other hand, a terminal device that receives a dynamic configuration message is called a dynamic TDD terminal (dynamic TDD UE).
0022FIG. 4 is an explanatory diagram for explaining the signaling of the link direction configuration using the dynamic configuration message.
0023The upper part of FIG. 4 shows how the legacy terminal periodically receives the SI message carrying the SIB1 in the cycle C1. SIB1 contains the identifier of the link-direction configuration currently configured for the legacy terminal (one of the configuration numbers 0-6 illustrated in Figure 2). According to this link direction configuration, the legacy terminal sets the link direction of its wireless communication circuit in subframe units. The signaling cycle C1 of the SI message is, for example, 320 msec. Here, assuming that the UL-DL traffic ratio fluctuates significantly 20 msec after receiving the SI message, the set link direction configuration and UL- The mismatch with the DL traffic ratio continues.
0024The lower part of FIG. 4 shows how the dynamic TDD terminal periodically receives the dynamic configuration message in the period C2 (<C1). The dynamic configuration message contains the identifier of the link-direction configuration currently configured for the dynamic TDD terminal (one of the configuration numbers 0-6 illustrated in Figure 2). According to this link direction configuration, the dynamic TDD terminal sets the link direction of its wireless communication circuit in subframe units. The signaling cycle C2 of the dynamic configuration message may be an integral multiple of 10 msec. For example, if the signaling cycle C2 = 40 msec, the duration of the mismatch between the link direction configuration and the UL-DL traffic ratio is 40 msec in the worst case.
0025As will be understood from FIG. 4, in the technology according to the present disclosure, the base station uses SI messages to signal the first link-direction configuration to the legacy terminal and uses the dynamic configuration message to the dynamic TDD terminal. Signal the second link direction configuration. As used herein, the first link-direction configuration that can be updated in period C1 is referred to as the legacy configuration. The second link-direction configuration that can be updated in period C2 is called the dynamic TDD configuration. Although the base station signals these two configurations, it actually operates according to the dynamic TDD configuration as described below.
0026As a result of the dynamic TDD configuration being updated less frequently than the legacy configuration, there is a link direction difference between these two configurations. Differences in link orientation between the two configurations can affect the synchronous behavior of legacy terminals and the timing of ACK / NACK and uplink permissions involving legacy terminals.
0027(2) Impact on synchronous operation of legacy terminals In general, the synchronous operation of the terminal device includes initial synchronization and synchronous tracking. Initial synchronization refers to synchronization from a state in which the operation timing of the terminal device is not synchronized with the operation timing of the base station at all. The initial synchronization is performed by the terminal device searching for PSS (Primary Synchronization Signal) and SSS (Secondary Synchronization Signal). Through the initial synchronization, the terminal device acquires the cell ID of the connected cell and knows the rough timing of the wireless frame. Synchronous tracking is performed to improve synchronization accuracy after the initial synchronization is complete. Synchronous tracking is performed by the terminal device receiving a CRS (Cell-specific Reference Symbol). As shown in Fig. 5A, CRS is, in principle, PDCCH (Physical Downlink Control Channel) and PDSCH (Physical Downlink Shared) of each downlink subframe. Channel) is inserted in a distributed manner. In both idle mode (RRC_Idle) and active mode (RRC_Connected), the terminal device receives the CRS of these downlink subframes regardless of the existence of data addressed to it, thereby adjusting the operation timing. Stay in sync. When the downlink subframe is set to the MBSFN (MBMS Single Frequency Network) subframe, the PDSCH of the downlink subframe is used only for broadcasting or multicasting the MBMS (Multimedia Broadcast Multicast Services) signal. .. As illustrated in Figure 5B, no CRS is inserted into the PDSCH of the MBSFN subframe.
0028Here, for example, it is assumed that Configuration2 is set as the legacy configuration and Configuration4 is set as the dynamic TDD configuration (see Fig. 2). Since the base station operates according to the dynamic TDD configuration, the link direction of the third subframe (# 3) is uplink, and the link direction of the seventh subframe (# 7) is downlink. However, the legacy terminal recognizes that the link direction of the third subframe is downlink and the link direction of the seventh subframe is uplink according to the legacy configuration. The legacy terminal then attempts to receive the CRS for synchronous tracking in the third subframe. However, the base station does not actually transmit the CRS in the subframe, which is the uplink subframe. As a result, there is a risk that the accuracy of synchronous tracking of legacy terminals will be reduced. In the 7th subframe, the base station transmits the CRS, but the legacy terminal does not receive the CRS. However, even if some CRSs are not received, the accuracy of synchronous tracking of the legacy terminal does not decrease, so the effect of the difference in the link direction of the 7th subframe is small.
0029The influence on the synchronous operation of the legacy terminal described above that may be caused by the introduction of the new dynamic configuration message can be solved by the first method or the second method described below.
0030(2-a) First method In the first method, a configuration with a higher uplink rate is set as the legacy configuration. Then, as the configuration for dynamic TDD, the configuration derived by replacing the uplink subframe of the legacy configuration with the downlink subframe is set. Special subframes may also be replaced by downlink subframes.
0031FIG. 6 is an explanatory diagram for explaining a first method for solving the influence of the difference in the link direction. The upper part of Figure 6 shows Configuration 0, which can be configured as a legacy configuration. The 0th and 5th subframes of Configuration0 are downlink subframes, the 1st and 6th subframes are special subframes, and the 2nd-4th and 7th-9th subframes are uplink subframes. .. The CRS is transmitted from the base station in the 0th and 5th subframes. The configuration for dynamic TDD may also be Configuration 0. However, if the UL-DL configuration ratio of Configuration 0 does not match the UL-DL traffic ratio, the configuration for dynamic TDD will make one or more of the uplink subframes (and special subframes) of Configuration 0 downlink subframes. Updates to one of the link-direction configurations derived by replacing with. In the lower example of Figure 6, the configuration for dynamic TDD is set to Configuration3. In Configuration3, the 6th subframe (special subframe) and the 7th to 9th subframes (uplink subframe) of Configuration0 are replaced with downlink subframes.
0032In the example of FIG. 6, in the 0th and 5th subframes in which the legacy terminal receives the CRS, the CRS is actually transmitted from the base station according to Configuration 3. Therefore, the legacy terminal can normally execute synchronous tracking by receiving these CRSs.
0033On the other hand, in the example of FIG. 6, when the legacy terminal transmits an uplink signal in, for example, the 7th subframe, the transmitted uplink signal is a base because the 7th subframe is actually a downlink subframe. Not received by the station. Rather, the uplink signal can cause harmful interference to the downlink signal (received by other terminal devices). Therefore, in the first method, the scheduler does not grant the uplink transmission of the legacy terminal for the subframe that has been replaced with the downlink subframe in the dynamic TDD configuration. As a result, it is possible to avoid unnecessary transmission of the uplink signal by the legacy terminal and prevent interference.
0034The matrix in Figure 7 shows the selectable combinations of legacy and dynamic TDD configurations in the first method. The horizontal axis of the matrix corresponds to the legacy configuration, and the vertical axis corresponds to the dynamic TDD configuration. The combination labeled "N" in the figure is a combination that is not selected in the first method. For example, if the legacy configuration is Configuration 0, all seven link-direction configurations can be selected as the dynamic TDD configuration. If the legacy configuration is Configuration 1, Configuration 1, 2, 4 and 5 can be selected as the dynamic TDD configuration. If the legacy configuration is Configuration 2, Configuration 2 and 5 can be selected as the dynamic TDD configuration. If the legacy configuration is Configuration 3, Configuration 3, 4 and 5 can be selected as the dynamic TDD configuration. If the legacy configuration is Configuration 4, Configuration 4 and 5 can be selected as the dynamic TDD configuration. If the legacy configuration is Configuration 5, only Configuration 5 can be selected as the dynamic TDD configuration. If the legacy configuration is Configuration 6, Configuration 1, 2, 3, 4, 5 and 6 can be selected as the dynamic TDD configuration. Any combination labeled "N" in the figure is a downsink subframe in the legacy configuration. , In the dynamic TDD configuration, there is a subframe that is an uplink subframe. By prohibiting the selection of such a combination, it is possible to prevent the legacy terminal from erroneously receiving a non-CRS signal when attempting to receive the CRS.
0035FIG. 8 is an explanatory diagram for explaining an example of the link direction configuration set in the first method along the time axis.
0036At time T11, the legacy terminal receives the SI message M01 and sets the Configuration 0 specified in the SI message M01 in its wireless communication circuit. The link direction configuration of the legacy terminal set here is maintained until the time T14 when the next SI message M02 is received. On the other hand, the dynamic TDD terminal receives the dynamic configuration message M11 at time T11 and sets the Configuration 0 specified in the message M11 in its own wireless communication circuit. After that, the dynamic TDD terminal receives the dynamic configuration message M12 at time T12, and sets the Configuration1 specified in the message M12 to its own wireless communication circuit. The link direction configuration of the dynamic TDD terminal set here is maintained until the time T13 when the next dynamic configuration message M13 is received. In Configuration1, the 4th and 9th uplink subframes in Configuration0 have been replaced with downlink subframes. Therefore, during the period from time T12 to time T13, uplink transmission of the legacy terminal in the 4th and 9th subframes is not permitted. At time T13, the dynamic TDD terminal receives the dynamic configuration message M13 and sets the Configuration 6 specified in the message M13 to its wireless communication circuit. The link direction configuration of the dynamic TDD terminal set here is maintained until the time when the next dynamic configuration message is received. In Configuration6, the 9th uplink subframe in Configuration0 has been replaced with a downlink subframe. Therefore, the configuration for dynamic TDD
0037Subsequently, at time T14, the legacy terminal receives the SI message M02 and sets the Configuration 3 specified in the SI message M02 in its wireless communication circuit. The link direction configuration of the legacy terminal set here is maintained until the time T17 when the next SI message is received. On the other hand, the dynamic TDD terminal receives the dynamic configuration message M16 at time T14, and sets the Configuration 3 specified in the message M16 to its own wireless communication circuit. After that, the dynamic TDD terminal receives the dynamic configuration message M17 at time T15, and sets the Configuration 4 specified in the message M17 to its own wireless communication circuit. The link direction configuration of the dynamic TDD terminal set here is maintained until the time T16 when the next dynamic configuration message M18 is received. In Configuration4, the fourth uplink subframe in Configuration3 has been replaced with a downlink subframe. Therefore, during the period from time T15 to time T16, uplink transmission of the legacy terminal in the fourth subframe is not permitted. At time T16, the dynamic TDD terminal receives the dynamic configuration message M18 and sets the Configuration 5 specified in the message M18 to its wireless communication circuit. The link direction configuration of the dynamic TDD terminal set here is maintained until the time when the next dynamic configuration message is received. In Configuration5, the 3rd and 4th uplink subframes in Configuration3 have been replaced with downlink subframes. Therefore, C as a configuration for dynamic TDD
0038(2-b) Second method In the second method, a configuration with a higher downlink rate is set as the legacy configuration. Also, at least one of the legacy configuration downlink subframes is set to the MBSFN subframe. Then, as the configuration for dynamic TDD, the configuration derived by replacing the downlink subframe set in the MBSFN subframe of the legacy configuration with the uplink subframe is set. Some MBSFN subframes may be replaced by special subframes.
0039FIG. 9 is an explanatory diagram for explaining a second method for solving the influence of the difference in the link direction. The upper part of Figure 9 shows Configuration 5, which can be configured as a legacy configuration. The 0th and 3rd to 9th subframes of Configuration 5 are downlink subframes, the first subframe is a special subframe, and the second subframe is an uplink subframe. However, as an example, the 3rd, 4th, 6th to 9th downlink subframes are set to MBSFN subframes. The CRS is transmitted from the base station in the 0th and 5th subframes. The configuration for dynamic TDD may also be Configuration 5. However, if the UL-DL configuration ratio of Configuration 5 does not match the UL-DL traffic ratio, the configuration for dynamic TDD will change one or more of the MBSFN subframes (and special subframes) of Configuration 5 to uplink subframes. Updates to one of the link-direction configurations derived by the replacement. In the lower example of Figure 9, the configuration for dynamic TDD is set to Configuration6. In Configuration6, the 3rd, 4th, 7th and 8th subframes (MBSFN subframes) of Configuration5 are replaced with uplink subframes. The sixth subframe of Configuration 5 (MBSFN subframe) has been replaced by a special subframe.
0040In the example of FIG. 9, in the 0th and 5th subframes in which the legacy terminal receives the CRS, the CRS is actually transmitted from the base station according to Configuration 6. Therefore, the legacy terminal can normally execute synchronous tracking by receiving these CRSs.
0041The matrix in Figure 10 shows the selectable combinations of legacy and dynamic TDD configurations in the second method. The horizontal axis of the matrix corresponds to the legacy configuration, and the vertical axis corresponds to the dynamic TDD configuration. The combination labeled "N" in the figure is a combination that is not selected in the second method. For example, if the legacy configuration is Configuration 0, only Configuration 0 can be selected as the dynamic TDD configuration. If the legacy configuration is Configuration 1, Configuration 0, 1 and 6 can be selected as the dynamic TDD configuration. If the legacy configuration is Configuration 2, Configuration 0, 1, 2 and 6 can be selected as the dynamic TDD configuration. If the legacy configuration is Configuration 3, Configuration 0, 3 and 6 can be selected as the dynamic TDD configuration. If the legacy configuration is Configuration 4, Configuration 0, 1, 3, 4 and 6 can be selected as the dynamic TDD configuration. If the legacy configuration is Configuration 5, all seven link-direction configurations can be selected as the dynamic TDD configuration. If the legacy configuration is Configuration 6, Configuration 0 and 6 can be selected as the dynamic TDD configuration.
0042FIG. 11 is an explanatory diagram for explaining an example of the link direction configuration set in the second method along the time axis.
0043At time T21, the legacy terminal receives the SI message M21 and sets the Configuration 5 specified in the SI message M21 in its wireless communication circuit. The link direction configuration of the legacy terminal set here is maintained until the time T24 when the next SI message M22 is received. On the other hand, the dynamic TDD terminal receives the dynamic configuration message M31 at time T21 and sets the Configuration2 specified in the message M31 in its own wireless communication circuit. After that, the dynamic TDD terminal receives the dynamic configuration message M32 at time T22, and sets the Configuration 4 specified in the message M32 to its own wireless communication circuit. The link direction configuration of the dynamic TDD terminal set here is maintained until the time T23 when the next dynamic configuration message M33 is received. At time T23, the dynamic TDD terminal receives the dynamic configuration message M33 and sets the Configuration 5 specified in the message M33 to its wireless communication circuit. The link direction configuration of the dynamic TDD terminal set here is maintained until the time when the next dynamic configuration message is received.
0044Subsequently, at time T24, the legacy terminal receives the SI message M22 and sets Configuration1 specified in the SI message M22 in its wireless communication circuit. The link direction configuration of the legacy terminal set here is maintained until the time T27 when the next SI message is received. On the other hand, the dynamic TDD terminal receives the dynamic configuration message M36 at time T24, and sets the Configuration1 specified in the message M36 to its own wireless communication circuit. After that, the dynamic TDD terminal receives the dynamic configuration message M37 at time T25, and sets the Configuration 0 specified in the message M37 to its own wireless communication circuit. The link direction configuration of the dynamic TDD terminal set here is maintained until the time when the next dynamic configuration message is received.
0045According to the first method or the second method described above, it is possible to prevent the introduction of the dynamic configuration message from adversely affecting the synchronous operation of the legacy terminal. In addition, since the dynamic configuration message can be transmitted in a shorter cycle than the SI message, the link direction configuration setting of the dynamic TDD terminal can be made to follow the fluctuation of the UL-DL traffic ratio more quickly.
0046FIG. 12 is an explanatory diagram for explaining an example of a control information area in which a dynamic configuration message is transmitted. With reference to FIG. 12, the schematic formats of the 0th and 5th subframes of each radio frame are shown. SIB1 is provided in the center of the PDSCH band of the fifth subframe. The dynamic configuration message may be transmitted, for example, on the E-PDCCH (Enhanced-Physical Downlink Control Channel) provided in the band of the PDSCH of the 0th or 5th subframe. Instead, dynamic configuration messages may be sent over the newly defined control information area within the PDCCH. By defining a new control information area for transmitting dynamic configuration messages in the E-PDCCH or PDCCH, it is possible to signal the link direction configuration in a cycle of 10 msec at the shortest.
0047It should be noted that an increase in the frequency of signaling results in an increase in signaling overhead. That is, there is a trade-off relationship between the responsiveness of updating the link direction configuration and the signaling overhead in terms of throughput. Therefore, the signaling cycle of the dynamic TDD configuration may be adaptively set for each system to optimize throughput, for example. In addition, signaling may be performed to notify the dynamic TDD terminal of the signaling cycle that is adaptively set.
0048(3) Impact on ACK / NACK transmitted by legacy terminals Acknowledgment (ACK) and negative response (NACK) are basic control signaling that is the basis of HARQ (Hybrid Automatic Repeat Request), which is a mechanism for ensuring the reliability of data transmission. The offset between the downlink transmission timing and the ACK / NACK timing is defined for each link direction configuration in Table 10.1.3.1-1 of 3GPP TS36.213 (see Table 1).
0049<tables num="1"><img id="000002" he="88" wi="152" file="JP6399178B2_D0001.tif" img-format="tif" img-content="drawing" /></tables>
0050Table 1 shows the timing offset between the downlink transmission and the ACK / NACK associated with the downlink transmission, in units of the number of subframes. The ACK / NACK transmission timing will be described with reference to FIG. The upper part of FIG. 13 shows two consecutive radio frames F11 and F12 in which Configuration 0 is set. In radio frames F11 and F12, downlink transmission can occur in the 0th, 1st, 5th and 6th subframes. Referencing the Configuration 0 row in Table 1, the ACK / NACK for the downlink transmission in the 0th subframe can be transmitted in the 4th subframe with offset 4. An ACK / NACK for the downlink transmission in the first subframe may be transmitted in the seventh subframe indicating offset 6. An ACK / NACK for the downlink transmission in the 5th subframe may be transmitted in the 9th subframe indicating offset 4. An ACK / NACK for downlink transmission in the sixth subframe may be transmitted in the second subframe (of the next radio frame) indicating offset 6. The correspondence between these timings is indicated by the dotted arrow in FIG. A device involved in wireless communication can store a specified table as shown in Table 1 in advance, and determine the transmission timing of ACK / NACK for downlink transmission by referring to the table.
0051However, if the dynamic TDD configuration and the legacy configuration are different, there are subframes with different link directions between these two configurations. In the example of FIG. 13, Configuration 5 is set as the configuration for dynamic TDD in the lower row. The legacy configuration is assumed to be Configuration0. In this case, the link directions are different in the 3rd, 4th, 7th, 8th and 9th subframes. Since the base station actually operates according to the dynamic TDD configuration, even if the legacy terminal transmits an ACK / NACK for downlink transmission in the 4th, 7th, or 9th subframe, the ACK / NACK is concerned. Is not received by the base station. If the ACK / NACK is lost, the base station cannot recognize that the corresponding downlink transmission has been performed normally, and may retransmit the transmitted data. This can waste radio resources and reduce system throughput.
0052Therefore, in one embodiment, the downlink transmission to the legacy terminal is scheduled only in the subframe in which the link direction does not differ in the associated subframe for ACK / NACK transmission. The subframes for ACK / NACK transmissions associated with downlink transmissions are indicated by the legacy configuration entries in Table 1. Whether or not there is a difference in the link direction in the subframe can be determined from the link direction of the subframe in the legacy configuration. If the subframe is specified as an uplink subframe in the legacy configuration, no link direction collision will occur. Otherwise, a link direction collision will occur. Now, referring to FIG. 2, the second subframe is the uplink subframe in any configuration. So, for example, if the legacy configuration is Configuration 0, the base station schedules downlink transmission to the legacy terminal in the sixth subframe (does not schedule it to other downlink subframes). As a result, regardless of the dynamic TDD configuration, it is possible to reliably receive the ACK / NACK for the downlink transmission from the legacy terminal in the second subframe.
0053(4) Impact on ACK / NACK sent to legacy terminals The offset between the uplink transmission timing and the ACK / NACK timing from the base station is defined for each link direction configuration in Table 9.1.2-1 of 3GPP TS36.213 (see Table 2).
0054<tables num="2"><img id="000003" he="66" wi="134" file="JP6399178B2_D0001.tif" img-format="tif" img-content="drawing" /></tables>
0055Table 2 shows the timing offset between the uplink transmission and the ACK / NACK associated with the uplink transmission, in units of the number of subframes. The ACK / NACK transmission timing will be described with reference to FIG. The upper part of FIG. 14 shows two consecutive radio frames F21 and F22 in which Configuration 0 is set. In radio frames F21 and F22, uplink transmissions can occur in the second, third, fourth, seventh, eighth and ninth subframes. Referencing the Configuration 0 row in Table 2, the ACK / NACK for the uplink transmission in the second subframe can be transmitted in the sixth subframe after offset 4. An ACK / NACK for the uplink transmission in the third subframe may be transmitted in the 0th subframe (of the next radio frame) after an offset of 7. An ACK / NACK for the uplink transmission in the 4th subframe may be transmitted in the 0th subframe (of the next radio frame) after offset 6. An ACK / NACK for the uplink transmission in the 7th subframe may be transmitted in the 1st subframe (of the next radio frame) after offset 4. An ACK / NACK for the uplink transmission in the 8th subframe may be transmitted in the 5th subframe (of the next radio frame) after an offset of 7. An ACK / NACK for the uplink transmission in the 9th subframe may be transmitted in the 5th subframe (of the next radio frame) after offset 6. The correspondence between these timings is indicated by the dotted arrow in FIG. A device involved in wireless communication can store a specified table as shown in Table 2 in advance, and determine the transmission timing of ACK / NACK for uplink transmission by referring to the table.
0056However, if the dynamic TDD configuration and the legacy configuration are different, there are subframes with different link directions between these two configurations. In the example of FIG. 14, Configuration 2 is set as the configuration for dynamic TDD in the lower row. The legacy configuration is assumed to be Configuration0. In this case, the link directions are different in the 3rd, 4th, 8th and 9th subframes. If the base station operates according to the configuration for dynamic TDD, the base station will ACK / NACK for uplink transmissions in the 2nd and 7th subframes, respectively, in the 8th subframe and (in the next radio frame). Send in the third subframe. However, in Configuration 0, which is the configuration for legacy, the third and eighth subframes are specified as uplink subframes, so the legacy terminal does not receive these ACKs / NACKs. If the ACK / NACK is lost, the legacy terminal cannot recognize that the corresponding uplink transmission has been performed normally, and may retransmit the transmitted data. This can waste radio resources and reduce system throughput.
0057Therefore, in one embodiment, the subframe for transmitting the ACK / NACK for the uplink transmission from the legacy terminal is determined by referring to the entry for the legacy configuration in Table 2. According to such criteria, in the example of FIG. 14, the base station performs ACK / NACK for uplink transmissions in the 2nd and 7th subframes, respectively, in the 6th subframe and 1 (of the next radio frame). Send in the second subframe. The first and sixth subframes are downlink subframes in both the legacy configuration and the dynamic TDD configuration. Therefore, the legacy terminal can normally receive these ACKs / NACKs.
0058(5) Impact on UL authorization sent to legacy terminals UL Grant (Uplink Grant) is a control signaling for notifying a terminal device that an uplink transmission has been scheduled. The timing offset between uplink transmission and UL authorization is defined for each link-direction configuration in Table 8-2 of 3GPP TS36.213 (see Table 3).
0059<tables num="3"><img id="000004" he="67" wi="134" file="JP6399178B2_D0001.tif" img-format="tif" img-content="drawing" /></tables>
0060Table 3 shows the timing offset between the uplink transmission and the UL allowance associated with that uplink transmission, in units of subframes. The UL permission transmission timing will be described with reference to FIG. The upper part of FIG. 15 shows two consecutive radio frames F31 and F32 in which Configuration 0 is set. In radio frames F31 and F32, uplink transmissions can occur in the second, third, fourth, seventh, eighth and ninth subframes. Referencing the Configuration 0 row in Table 3, UL authorization for uplink transmission in the second subframe may be transmitted in the sixth subframe (of the previous radio frame) indicating offset 6. UL permission for uplink transmission in the third subframe may be transmitted in the sixth subframe (of the previous radio frame) indicating offset 7. UL permission for uplink transmission in the 4th subframe may be transmitted in the 0th subframe indicating offset 4. UL permission for uplink transmission in the 7th subframe may be transmitted in the 1st subframe indicating offset 6. UL authorization for uplink transmission in the 8th subframe may be transmitted in the 1st subframe indicating offset 7. UL permission for uplink transmission in the 9th subframe may be transmitted in the 5th subframe indicating offset 4. The correspondence between these timings is indicated by the dotted arrow in FIG. The device involved in wireless communication can store the specified table as shown in Table 3 in advance, and determine the transmission timing of UL permission for uplink transmission by referring to the table.
0061However, if the configuration and legacy for configuration for dynamic TDD is different, these two configurator exist different subframes of the link direction between Shon. In the example of FIG. 15, Configuration 2 is set as the configuration for dynamic TDD in the lower row. The legacy configuration is assumed to be Configuration0. In this case, the link directions are different in the 3rd, 4th, 8th and 9th subframes. If the base station operates according to the configuration for dynamic TDD, the base station grants UL permission for uplink transmission in the 2nd and 7th subframes, respectively, in the 8th subframe (of the previous radio frame) and Send in the third subframe. However, in Configuration 0, which is the configuration for legacy, the third and eighth subframes are specified as uplink subframes, so the legacy terminal does not receive these UL permits. If the UL permission is not received, the legacy terminal will not perform the uplink transmission and the uplink traffic will be blocked.
0062Therefore, in one embodiment, the subframe for transmitting the uplink permission corresponding to the uplink transmission from the legacy terminal is determined by referring to the entry for the legacy configuration in Table 3. For example, according to such criteria, in the example of FIG. 15, the base station grants UL permission for uplink transmission in the second and seventh subframes, respectively, in the sixth subframe (of the previous radio frame). And send in the first subframe. The first and sixth subframes are downlink subframes in both the legacy configuration and the dynamic TDD configuration. Therefore, the legacy terminal can normally receive these UL permits.
0063<2. Communication control system configuration> [2-1. System overview] FIG. 16 is an explanatory diagram showing an example of the configuration of the communication control system 1 according to the embodiment in which the technique according to the present disclosure is implemented. Referring to FIG. 16, the communication control system 1 includes a base station 100. The base station (eNB) 100 provides wireless communication services to the legacy terminal 10 and the dynamic TDD terminal 30 located inside the cell 102 according to the TD-LTE method. The base station 100 is connected to a core network 104, which is typically realized as an EPC (Evolved Packet Core). The core network 104 includes various control nodes such as MME (Mobility Management Entity), S-GW (Serving Gateway) and P-GW.
0064The legacy terminal 10 is a terminal device that operates according to the legacy configuration. The dynamic TDD terminal 30 is a terminal device capable of operating according to the configuration for dynamic TDD. The dynamic TDD terminal 30 may additionally be capable of operating according to the legacy configuration. The control function that sets the legacy configuration for one or more legacy terminals 10 and the dynamic TDD configuration for one or more dynamic TDD terminals 30 is base station 100, or base station 100. It can be located at any control node that communicates with these terminal devices via. In the following description, as an example, it is assumed that the base station 100 has the control function.
0065[2-2. Legacy terminal configuration example] FIG. 17 is a block diagram showing an example of the configuration of the legacy terminal 10. Referring to FIG. 17, the legacy terminal 10 includes a wireless communication unit 11, a signal processing unit 12, a control unit 13, and a memory 14.
0066(1) Wireless communication unit The wireless communication unit 11 is a communication interface for the legacy terminal 10 to send and receive wireless signals to and from the base station 100. The radio communication unit 11 has one or more antennas (not shown) and an RF (Radio Frequency) circuit. The wireless communication unit 11 receives the downlink signal transmitted from the base station 100, and performs amplification, frequency conversion, and AD (Analogue-to-Digital) conversion of the received signal. Further, the wireless communication unit 11 performs DA (Digital-to-Analogue) conversion, frequency conversion and amplification of the transmission signal, and transmits the uplink signal to the base station 100.
0067The downlink signal received by the wireless communication unit 11 includes a downlink data signal and a downlink signaling. The downlink signaling includes SI message notifying the legacy terminal 10 of the legacy configuration, ACK / NACK and UL permission for uplink transmission. Further, the uplink signal transmitted by the wireless communication unit 11 includes an uplink data signal and an uplink signaling. Uplink signaling includes a buffer status report showing the traffic volume of the uplink data signal waiting in the buffer, and ACK / NACK for downlink transmission.
0068(2) Signal processing unit The signal processing unit 12 has a signal processing circuit for equalizing, demodulating and decoding the received signal input from the wireless communication unit 11, and encoding and modulating the transmitted signal output to the wireless communication unit 11. The signal processing unit 12 is connected to, for example, a processor (not shown) that realizes processing of an upper layer. Then, the signal processing unit 12 outputs the data included in the demodulated and decoded received signal to the upper layer. Further, the signal processing unit 12 encodes and modulates a transmission signal including data input from the upper layer.
0069(3) Control unit The control unit 13 controls wireless communication by the legacy terminal 10 according to the TD-LTE method. For example, the control unit 13 sets the link direction for each subframe to the wireless communication unit 11 and the signal processing unit 12 according to the legacy configuration specified in the SI message received by the wireless communication unit 11. Further, the control unit 13 causes the wireless communication unit 11 to receive the downlink signal according to the downlink allocation received by the wireless communication unit 11, and outputs an ACK when the reception is successful and an NACK when the reception is unsuccessful. Send it back to the wireless communication unit 11. Further, the control unit 13 causes the wireless communication unit 11 to transmit an uplink signal in accordance with the uplink permission received by the wireless communication unit 11, and causes the wireless communication unit 11 to receive an ACK or NACK for the uplink transmission. The control unit 13 stores the transmission / reception timing of these control signalings (that is, ACK / NACK for downlink transmission, ACK / NACK for uplink transmission, and UL permission) in the memory 14 (Table 1 described above, Table 1 above). It can be determined by referring to the entries for legacy configurations in Tables 2 and 3). Further, the control unit 13 causes the wireless communication unit 11 to receive the CRS in the downlink subframe that is not set in the MBSFN subframe, and causes the wireless communication unit 11 to execute synchronous tracking. Further, the control unit 13 periodically generates a buffer status report indicating the amount of traffic of the uplink data signal waiting in the buffer, and transmits the generated buffer status report from the wireless communication unit 11 to the base station 100.
0070(4) Memory The memory 14 is a storage medium for storing data and programs used by the control unit 13 to control wireless communication by the legacy terminal 10. For example, memory 14 stores the currently set identifier for the legacy configuration. Further, the memory 14 has a first table (Table 1) that associates the downlink transmission timing with the corresponding ACK / NACK timing, and a second table that associates the uplink transmission timing with the corresponding ACK / NACK timing. A table (Table 2) and a third table (Table 3) that associates the timing of uplink transmission with the corresponding timing of UL authorization are stored in advance.
0071[2-3. Configuration example of dynamic TDD terminal] FIG. 18 is a block diagram showing an example of the configuration of the dynamic TDD terminal 30. Referring to FIG. 18, the dynamic TDD terminal 30 includes a wireless communication unit 31, a signal processing unit 32, a control unit 33, and a memory 34.
0072(1) Wireless communication unit The wireless communication unit 31 is a communication interface for the dynamic TDD terminal 30 to send and receive wireless signals to and from the base station 100. The wireless communication unit 31 has one or more antennas (not shown) and an RF circuit. The wireless communication unit 31 receives the downlink signal transmitted from the base station 100, and performs amplification, frequency conversion, and AD conversion of the received signal. Further, the wireless communication unit 31 performs DA conversion, frequency conversion and amplification of the transmission signal, and transmits the uplink signal to the base station 100.
0073The downlink signal received by the wireless communication unit 31 includes a downlink data signal and a downlink signaling. The downlink signaling includes a dynamic configuration message notifying the dynamic TDD terminal 30 of the configuration for dynamic TDD, ACK / NACK and UL permission for uplink transmission. Further, the uplink signal transmitted by the wireless communication unit 31 includes an uplink data signal and an uplink signaling. Uplink signaling includes a buffer status report showing the traffic volume of the uplink data signal waiting in the buffer, and ACK / NACK for downlink transmission.
0074(2) Signal processing unit The signal processing unit 32 has a signal processing circuit for equalizing, demodulating and decoding the received signal input from the wireless communication unit 31, and encoding and modulating the transmitted signal output to the wireless communication unit 31. The signal processing unit 32 is connected to, for example, a processor (not shown) that realizes processing of an upper layer. Then, the signal processing unit 32 outputs the data included in the demodulated and decoded received signal to the upper layer. Further, the signal processing unit 32 encodes and modulates a transmission signal including data input from the upper layer.
0075(3) Control unit The control unit 33 controls wireless communication by the dynamic TDD terminal 30 according to the TD-LTE method. For example, the control unit 33 causes the wireless communication unit 31 to receive a dynamic configuration message transmitted in a control information area different from that of the SIB. The dynamic configuration message is signaled from the base station 100 in a cycle shorter than the signaling cycle of the SI message. Then, the control unit 33 sets the link direction for each subframe to the wireless communication unit 31 and the signal processing unit 32 according to the dynamic TDD configuration specified in the dynamic configuration message. Further, the control unit 33 causes the wireless communication unit 31 to receive the downlink signal according to the downlink allocation received by the wireless communication unit 31, and outputs an ACK when the reception is successful and an NACK when the reception is unsuccessful. Send it back to the wireless communication unit 31. Further, the control unit 33 causes the wireless communication unit 31 to transmit an uplink signal in accordance with the uplink permission received by the wireless communication unit 31, and causes the wireless communication unit 31 to receive an ACK or NACK for the uplink transmission. The control unit 33 stores the transmission / reception timing of these control signalings (that is, ACK / NACK for downlink transmission, ACK / NACK for uplink transmission, and UL permission) in the memory 34 (Table 1 described above, Table 1 above). It can be determined by referring to the entries for dynamic TDD configurations in Tables 2 and 3). Further, the control unit 33 causes the wireless communication unit 31 to receive the CRS in the downlink subframe and execute the synchronous tracking. Further, the control unit 33 periodically generates a buffer status report indicating the traffic volume of the uplink data signal waiting in the buffer, and transmits the generated buffer status report from the wireless communication unit 31 to the base station 100.
0076(4) Memory The memory 34 is a storage medium for storing data and programs used by the control unit 33 to control wireless communication by the dynamic TDD terminal 30. For example, memory 34 stores the currently set identifier for the dynamic TDD configuration. In addition, the memory 34 has a first table (Table 1) that associates the downlink transmission timing with the corresponding ACK / NACK timing, and a second table that associates the uplink transmission timing with the corresponding ACK / NACK timing. A table (Table 2) and a third table (Table 3) that associates the timing of uplink transmission with the corresponding timing of UL authorization are stored in advance.
0077(5) Dual mode support The dynamic TDD terminal 30 has a first operation mode in which the link direction is set according to the legacy configuration and a second operation mode in which the link direction is set according to the dynamic TDD configuration in a shorter cycle as in the legacy terminal 10. It may be possible to operate in both. For example, the dynamic TDD terminal 30 receives SI messages infrequently in idle mode (RRC_Idle) (ie, the first operating mode) and receives dynamic configuration messages frequently in active mode (RRC_Connected) (ie,). Second operation mode) may be used. As a result, it is possible to avoid an increase in power consumption in the idle mode. Further, the dynamic TDD terminal 30 may receive the dynamic configuration message only during the period instructed by the base station 100 in the active mode.
0078[2-4. Configuration example of communication control device] In this embodiment, the base station 100 has a role as a communication control device that controls wireless communication performed by one or more terminal devices according to a time division duplex (TDD) system. FIG. 19 is a block diagram showing an example of the configuration of the base station 100. Referring to FIG. 19, the base station 100 includes a wireless communication unit 110, a signal processing unit 120, an interface unit 130, a setting unit 140, a signaling control unit 150, a scheduling unit 160, and a storage unit 170.
0079(1) Wireless communication unit The wireless communication unit 110 is a communication interface for the base station 100 to transmit and receive wireless signals to and from one or more terminal devices. The wireless communication unit 110 has one or more antennas (not shown) and an RF circuit. The wireless communication unit 110 receives the uplink signal transmitted from the terminal device, and performs amplification, frequency conversion, and AD conversion of the received signal. Further, the wireless communication unit 110 performs DA conversion, frequency conversion and amplification of the transmission signal, and transmits the downlink signal to the terminal device. The link direction of the wireless communication unit 110 changes in subframe units according to the dynamic TDD configuration set by the setting unit 140.
0080The uplink signal received by the wireless communication unit 110 includes an uplink data signal and an uplink signaling. Uplink signaling includes a buffer status report from each terminal and ACK / NACK for downlink transmission. Further, the downlink signal transmitted by the wireless communication unit 110 includes a downlink data signal and a downlink signaling. Downlink signaling includes SI messages for notifying legacy configurations, dynamic configuration messages for notifying dynamic TDD configurations, ACK / NACK for uplink transmissions, and UL authorization.
0081(2) Signal processing unit The signal processing unit 120 has a signal processing circuit for equalizing, demodulating and decoding the received signal input from the wireless communication unit 110, and encoding and modulating the transmitted signal output to the wireless communication unit 110. The signal processing unit 120 outputs the data included in the demodulated and decoded received signal to the interface unit 130. Further, the signal processing unit 120 encodes and modulates a transmission signal including data input from the interface unit 130.
0082(3) Interface section The interface unit 130 is a communication interface such as an X2 interface for the base station 100 to communicate with another base station and an S1 interface for the base station 100 to communicate with a control node in the core network 104. Including groups. Each communication interface of the interface unit 130 may be a wired communication interface or a wireless communication interface. The interface unit 130 receives buffer signaling from, for example, the P-GW. The buffer signaling indicates the traffic volume of the downlink data signal waiting for the buffer for each terminal device. The interface unit 130 outputs the received buffer signaling to the setting unit 140.
0083(4) Setting section The setting unit 140 sets a link direction configuration indicating a link direction in units of subframes for each of the radio frames including a plurality of subframes. More specifically, the configuration unit 140 sets the legacy configuration for a first terminal group that includes one or more legacy terminals 10. In addition, the setting unit 140 sets the configuration for dynamic TDD for the second terminal group including one or more dynamic TDD terminals 30. The setting unit 140 may select the legacy configuration and the dynamic TDD configuration to be set for each radio frame based on the UL-DL traffic ratio. For example, configuration unit 140 may choose a link-direction configuration with a higher uplink rate if more uplink traffic is waiting for the buffer. Similarly, the configuration unit 140 may select a link-direction configuration with a high downlink rate if more downlink traffic is waiting for the buffer.
0084In the present embodiment, the setting unit 140 supports two types of setting modes, a semi-static mode and a dynamic mode. In the semi-static mode, the setting unit 140 sets the same link direction configuration as the legacy configuration as the dynamic TDD configuration. In the dynamic mode, the setting unit 140 can set a link direction configuration different from the legacy configuration as a dynamic TDD configuration (the same link direction configuration can be set for each other). The transition between semi-static mode and dynamic mode can be triggered by a buffer status report from legacy terminal 10 or buffer signaling from P-GW. An example of such a mode transition will be described in detail later.
0085In dynamic mode, the setting unit 140 typically goes from a set of configurations limited based on the legacy configuration set up for the first terminal group to the radio communication unit 110 and the signal processing unit 120. Select the configuration for dynamic TDD to be set.
0086For example, in the first method, the setting unit 140 first sets a link direction configuration having a higher uplink rate as a legacy configuration. Then, the setting unit 140 sets the link direction configuration guided by replacing the uplink subframe of the legacy configuration with the downlink subframe as the configuration for dynamic TDD.
0087Further, for example, in the second method, the setting unit 140 first sets a link direction configuration having a higher downlink rate as the legacy configuration. In addition, the setting unit 140 sets at least one of the downlink subframes of the set legacy configuration to the MBSFN subframe. Then, the setting unit 140 sets the link direction configuration guided by replacing the MBSFN subframe of the legacy configuration with the uplink subframe as the configuration for dynamic TDD.
0088(5) Signaling control unit The signaling control unit 150 signals the link direction configuration set by the setting unit 140 to each terminal device. More specifically, the signaling control unit 150 signals the legacy configuration to the legacy terminal 10 by broadcasting an SI message in the signaling cycle C1. Further, the signaling control unit 150 signals the dynamic TDD configuration to the dynamic TDD terminal 30 by transmitting a dynamic configuration message in a signaling cycle C2 shorter than the signaling cycle C1. The transmission of SI messages or dynamic configuration messages may be skipped when the link-direction configuration is not updated.
0089The signaling control unit 150 also controls transmission of a CRS (Cell-specific Reference Symbol) from the wireless communication unit 110. More specifically, the signaling control unit 150 causes the wireless communication unit 110 to transmit a CRS on the PDCCH and PDSCH of the downlink subframe set according to the configuration for dynamic TDD.
0090Further, the signaling control unit 150 is a dynamic TDD terminal 30 (dual mode terminal) capable of operating in both the first operation mode and the second operation mode described above when the UL-DL traffic ratio satisfies a predetermined condition. May be instructed to switch to a second operating mode (a mode for receiving dynamic configuration messages). The predetermined condition here may be, for example, that the magnitude or speed of the fluctuation of the UL-DL traffic ratio exceeds the threshold value.
0091(6) Scheduling section The scheduling unit 160 schedules the transmission of the downlink signal from the base station 100 to each terminal device and the transmission of the uplink signal from each terminal device to the base station 100. The scheduling unit 160 generates scheduling information indicating the result of scheduling. The signaling control unit 150 transmits the scheduling information (downlink allocation and uplink permission) generated by the scheduling unit 160 to each terminal device via the wireless communication unit 110.
0092When the first method is adopted, the scheduling unit 160 does not allow the uplink transmission of the legacy terminal 10 for the subframe in which the uplink subframe is replaced with the downlink subframe in the dynamic TDD configuration. Thereby, it is possible to prevent the uplink signal from the legacy terminal 10 from causing harmful interference.
0093Further, the scheduling unit 160 can schedule the downlink transmission to the legacy terminal only to the subframes for which the link direction does not differ in the subframes for ACK / NACK transmission associated with the downlink transmission. The subframes for ACK / NACK transmissions associated with downlink transmissions are indicated by the legacy configuration entries in the first table (Table 1) stored by storage 170. As described above, whether or not a difference in the link direction occurs in the subframe can be determined from the link direction of the subframe in the legacy configuration. In addition, the scheduling unit 160 stores the subframes for transmitting ACK / NACK for the uplink transmission of the legacy terminal for the legacy configuration in the second table (Table 2) stored by the storage unit 170. It can be determined by referring to the entry in. In addition, the scheduling unit 160 contains a subframe for transmitting UL permission for uplink transmission of the legacy terminal, and an entry for the legacy configuration in the third table (Table 3) stored by the storage unit 170. Can be determined by referring to.
0094(7) Memory The storage unit 170 is a storage medium that stores data and programs used by the base station 100 to control wireless communication in the cell 102. For example, the storage unit 170 stores in advance a set of configuration candidates that can be selected by the base station 100. Further, the storage unit 170 stores the identifiers of the legacy configuration and the dynamic TDD configuration set by the setting unit 140. Further, the storage unit 170 has a first table (Table 1) that associates the downlink transmission timing with the corresponding ACK / NACK timing, and a second table that associates the uplink transmission timing with the corresponding ACK / NACK timing. Table (Table 2) and a third table (Table 3) that associates the uplink transmission timing with the corresponding UL authorization timing are stored in advance.
0095[2-5. Transition of setting mode] (1) First method FIG. 20 is a state transition diagram showing an example of the transition between the setting modes in the first method. With reference to FIG. 20, a first state ST1 and a second state ST2 belonging to the semi-static mode, and a third state ST3 belonging to the dynamic mode are shown.
0096State ST1 is the basic state in semi-static mode. In state ST1, the configuration for dynamic TDD is not updated in a short cycle. Both the legacy configuration and the dynamic TDD configuration are set to a link direction configuration with a higher downlink rate (eg, Configuration 5).
0097State ST2 is a state that appears temporarily during the transition between semi-static mode and dynamic mode. In state ST2, both the legacy configuration and the dynamic TDD configuration are set to the link direction configuration with a higher uplink rate (eg, Configuration 0).
0098State ST3 is the basic state in dynamic mode. In state ST3, the configuration for dynamic TDD is updated in a short cycle. The legacy configuration is set to a link-direction configuration with a higher uplink rate, similar to state ST2. The configuration for dynamic TDD may be different from the configuration for legacy. In state ST3, the setting unit 140 adaptively changes the dynamic TDD configuration so that the UL-DL configuration ratio of the dynamic TDD configuration follows the UL-DL traffic ratio.
0099The setting unit 140 is semi-static when, for example, the amount of downlink traffic buffered for the legacy terminal 10 in the P-GW exceeds the first threshold while operating in the dynamic mode (that is, state ST3). Transition to mode. In this case, the state of the setting mode transitions from the state ST3 to the state ST1 via the state ST2. Downlink traffic for legacy terminal 10 is released from the buffer by setting a higher link direction configuration in state ST1. Then, the setting unit 140 is dynamically operated when the amount of downlink traffic buffered for the legacy terminal 10 in the P-GW falls below the second threshold value while operating in the semi-static mode (that is, the state ST1). Transition to mode. In this case, the state of the setting mode transitions from the state ST1 through the state ST2 to the state ST3. By returning the setting mode to the dynamic mode in this way, it becomes possible again to make the link direction configuration of the dynamic TDD terminal 30 follow the fluctuation of the UL-DL traffic ratio more quickly.
0100(2) Second method FIG. 21 is a state transition diagram showing an example of the transition between the setting modes in the second method. With reference to FIG. 21, a first state ST1 and a second state ST2 belonging to the semi-static mode, and a third state ST3 belonging to the dynamic mode are shown.
0101State ST1 is the basic state in semi-static mode. In state ST1, the configuration for dynamic TDD is not updated in a short cycle. The configuration unit 140 adaptively changes the legacy configuration to follow the UL-DL traffic ratio. The configuration for dynamic TDD is equal to the configuration for legacy.
0102State ST2 is a state that appears temporarily during the transition between semi-static mode and dynamic mode. In state ST2, both the legacy configuration and the dynamic TDD configuration are set to the link direction configuration with a higher downlink rate (eg, Configuration 5).
0103State ST3 is the basic state in dynamic mode. In state ST3, the configuration for dynamic TDD is updated in a short cycle. The legacy configuration is set to a link-direction configuration with a higher downlink rate, similar to state ST2. At least one downlink subframe is set to the MBSFN subframe. The configuration for dynamic TDD may be different from the configuration for legacy. In state ST3, the setting unit 140 adaptively changes the dynamic TDD configuration so that the UL-DL configuration ratio of the dynamic TDD configuration follows the UL-DL traffic ratio.
0104For example, when the setting unit 140 is operating in the dynamic mode (that is, the state ST3), when the amount of downlink traffic or the amount of uplink traffic waiting for the buffer for the legacy terminal 10 exceeds the first threshold value, the setting unit 140 is set to semi. Transition to static mode. In this case, the state of the setting mode transitions from the state ST3 to the state ST1 via the state ST2. In state ST1, traffic waiting for a buffer for legacy terminal 10 is released from the buffer. Then, the setting unit 140 transitions to the dynamic mode when the amount of traffic waiting for the buffer for the legacy terminal 10 falls below the second threshold value during the operation in the semi-static mode (that is, the state ST1). In this case, the state of the setting mode transitions from the state ST1 through the state ST2 to the state ST3. By returning the setting mode to the dynamic mode in this way, it becomes possible again to make the link direction configuration of the dynamic TDD terminal 30 follow the fluctuation of the UL-DL traffic ratio more quickly.
0105<3. Example of processing flow> [3-1. Processing on the terminal side] FIG. 22 is a flowchart showing an example of the flow of communication processing executed by the dynamic TDD terminal 30. Here, it is assumed that the dynamic TDD terminal 30 is the dual mode terminal described above.
0106The communication process of FIG. 22 first branches according to whether the dynamic TDD terminal 30 is operating in the first operation mode or the second operation mode (step S10). If the dynamic TDD terminal 30 is operating in the first operating mode, the process proceeds to step S15. On the other hand, if the dynamic TDD terminal 30 is operating in the second operation mode, the process proceeds to step S25.
0107In the first operation mode, the control unit 33 causes the wireless communication unit 31 to receive the SI message in the first signaling cycle (step S15). Then, when the SI message is received by the wireless communication unit 31, the control unit 33 transfers the link direction configuration (that is, the legacy configuration) specified by the SI message to the wireless communication unit 31 and the signal processing unit 32. Set (step S20).
0108On the other hand, in the second operation mode, the control unit 33 causes the radio communication unit 31 to receive the dynamic configuration message in the shorter second signaling cycle (step S25). Then, when the dynamic configuration message is received by the wireless communication unit 31, the control unit 33 applies the link direction configuration (that is, the configuration for dynamic TDD) specified by the dynamic configuration message to the wireless communication unit 31 and the wireless communication unit 31. Set in the signal processing unit 32 (step S30).
0109Further, the control unit 33 causes the wireless communication unit 31 to receive the downlink data signal or transmits the uplink data signal from the wireless communication unit 31 according to the scheduling information received by the wireless communication unit 31 (step S35). Further, the wireless communication unit 31 transmits a buffer status report indicating the amount of uplink traffic waiting in the buffer to the base station 100 (step s40).
0110Next, the control unit 33 determines whether or not the operation mode switching is instructed by the base station 100 (step S45). Here, when the operation mode switching is instructed, the control unit 33 switches the current operation mode to another operation mode (step S50). Then, the communication process of FIG. 22 returns to step S10.
0111[3-2. Processing on the network side] (1) First method 23A and 23B are flowcharts showing an example of the flow of communication control processing executed by the base station 100 according to the first method.
0112Referring to FIG. 23A, the communication control process first branches depending on whether the base station 100 is operating in the semi-static mode or the dynamic mode (step S110). If the base station 100 is operating in the semi-static mode, the process proceeds to step S115. On the other hand, if the base station 100 is operating in the dynamic mode, the process proceeds to step S155 in FIG. 23B.
0113In step S115, the setting unit 140 determines whether or not the transition condition to the dynamic mode is satisfied (step S115). Here, if the transition condition to the dynamic mode is not satisfied, the semi-static mode is maintained and the process proceeds to step S120. On the other hand, if the transition condition to the dynamic mode is satisfied, the process proceeds to step S130.
0114In step S120, the setting unit 140 sets the legacy configuration and the dynamic TDD configuration according to the UL-DL traffic ratio (step S120). In general, a common link-direction configuration with a high downlink rate may be selected. Next, the signaling control unit 150 signals the set link direction configuration to the legacy terminal 10 and the dynamic TDD terminal 30 (step S125). The processing of steps S120 and S125 is performed in the signaling cycle C1 which may correspond to 640 msec or 320 msec.
0115In step S130, the setting unit 140 sets the legacy configuration and the dynamic TDD configuration to the link direction configuration having a high uplink rate (step S130). Next, the signaling control unit 150 signals the set link direction configuration to the legacy terminal 10 and the dynamic TDD terminal 30 (step S135). Then, the setting mode shifts to the dynamic mode, and the process proceeds to step S160 in FIG. 23B (step S140).
0116Referring to FIG. 23B, in step S155, the setting unit 140 determines whether or not the transition condition to the semi-static mode is satisfied (step S155). Here, if the transition condition to the semi-static mode is not satisfied, the dynamic mode is maintained and the process proceeds to step S160. On the other hand, if the transition condition to the semi-static mode is satisfied, the process proceeds to step S170.
0117In step S160, the setting unit 140 sets the configuration for dynamic TDD according to the UL-DL traffic ratio (step S160). The legacy configuration does not have to be updated. Next, the signaling control unit 150 signals the set dynamic TDD configuration to the dynamic TDD terminal 30 (step S165). The processing of steps S160 and S165 is performed in a signaling cycle C2 that can correspond to an integral multiple of 10 msec.
0118In step S170, the configuration unit 140 sets the dynamic TDD configuration to the same link-direction configuration as the legacy configuration (step S170). Next, the signaling control unit 150 signals the set dynamic TDD configuration to the dynamic TDD terminal 30 (step S175). Then, the setting mode shifts to the semi-static mode, and the process proceeds to step S120 in FIG. 23A (step S180).
0119(2) Second method 24A and 24B are flowcharts showing an example of the flow of communication control processing executed by the base station 100 according to the second method.
0120Referring to FIG. 24A, the communication control process first branches depending on whether the base station 100 is operating in the semi-static mode or the dynamic mode (step S210). If the base station 100 is operating in the semi-static mode, the process proceeds to step S215. On the other hand, if the base station 100 is operating in the dynamic mode, the process proceeds to step S255 in FIG. 24B.
0121In step S215, the setting unit 140 determines whether or not the transition condition to the dynamic mode is satisfied (step S215). Here, if the transition condition to the dynamic mode is not satisfied, the semi-static mode is maintained and the process proceeds to step S220. On the other hand, if the transition condition to the dynamic mode is satisfied, the process proceeds to step S230.
0122In step S220, the setting unit 140 sets the legacy configuration and the dynamic TDD configuration according to the UL-DL traffic ratio (step S220). Next, the signaling control unit 150 signals the set link direction configuration to the legacy terminal 10 and the dynamic TDD terminal 30 (step S225). The processing of step S220 and step S225 is performed in the signaling cycle C1 which may correspond to 640 msec or 320 msec.
0123In step S230, the setting unit 140 sets the legacy configuration and the dynamic TDD configuration to the link direction configuration having a high downlink rate (step S230). Next, the setting unit 140 sets at least one downlink subframe to the MBSFN subframe (step S235). Next, the signaling control unit 150 signals the set link direction configuration to the legacy terminal 10 and the dynamic TDD terminal 30 (step S240). Then, the setting mode shifts to the dynamic mode, and the process proceeds to step S260 in FIG. 24B (step S245).
0124Referring to FIG. 24B, in step S255, the setting unit 140 determines whether or not the transition condition to the semi-static mode is satisfied (step S255). Here, if the transition condition to the semi-static mode is not satisfied, the dynamic mode is maintained and the process proceeds to step S260. On the other hand, if the transition condition to the semi-static mode is satisfied, the process proceeds to step S270.
0125In step S260, the setting unit 140 sets the configuration for dynamic TDD according to the UL-DL traffic ratio (step S260). The legacy configuration does not have to be updated. Next, the signaling control unit 150 signals the set dynamic TDD configuration to the dynamic TDD terminal 30 (step S265). The processing of steps S260 and S265 is performed in a signaling cycle C2 that can correspond to an integral multiple of 10 msec.
0126In step S270, the configuration unit 140 sets the dynamic TDD configuration to the same link-direction configuration as the legacy configuration (step S270). Next, the setting unit 140 cancels the setting of the MBSFN subframe (step S275). Next, the signaling control unit 150 signals the set dynamic TDD configuration to the dynamic TDD terminal 30 (step S280). Then, the setting mode shifts to the semi-static mode, and the process proceeds to step S220 of FIG. 24A (step S285).
0127<4. Summary> Up to this point, embodiments of the technique according to the present disclosure have been described in detail with reference to FIGS. 1 to 24B. According to the embodiments described above, a first link directional configuration (legacy configuration) is configured for the legacy terminal and a second link directional configuration (dynamic TDD configuration) for the dynamic TDD terminal. Is set. The first link-direction configuration is signaled to the legacy terminal within the SIB. The second link-direction configuration is signaled to the dynamic TDD terminal in a shorter cycle than the signaling cycle of the first link-direction configuration. Therefore, it is possible to make the link direction configuration of the dynamic TDD terminal follow the fluctuation of the UL-DL traffic ratio more quickly than the existing mechanism. As a result, even in a wireless communication environment in which the UL-DL traffic ratio fluctuates drastically, it is possible to avoid or mitigate a decrease in resource efficiency and a decrease in throughput due to an increase in the amount of traffic waiting for a buffer.
0128Also, according to the embodiments described above, the dynamic TDD configuration may be selected from a limited set of configurations based on the configured legacy configuration. As a result, it is possible to prevent the accuracy of synchronous tracking using CRS from being lowered in the legacy terminal due to the difference in the link direction configuration.
0129Further, according to the above-described embodiment, when the amount of traffic buffered for the legacy terminal exceeds a predetermined threshold value in the dynamic mode, the setting of the dynamic TDD configuration different from the legacy configuration is set. It will be temporarily stopped. As a result, the traffic for the legacy terminal waiting for the buffer can be eliminated. When the traffic is cleared, the configuration mode of the link direction configuration returns to dynamic mode. This can facilitate the rapid follow-up of the dynamic TDD terminal's link-direction configuration to fluctuations in the UL-DL traffic ratio, while ensuring proper buffer control of the legacy terminal.
0130Further, according to the above-described embodiment, the timing of ACK / NACK transmitted from the legacy terminal or transmitted to the legacy terminal, or the timing of UL permission transmitted to the legacy terminal is the link direction between the two configurations. Can be controlled so as not to be affected by the difference between. Therefore, the loss of ACK / NACK or UL permission due to the difference in the link direction is avoided, and the communication resource can be used efficiently.
0131It should be noted that some features described herein are based on, for example, limiting candidates for dynamic TDD configurations based on legacy configurations, transitions between dynamic and semi-static modes, and UL-DL traffic ratios. Switching the operating mode of a dual-mode terminal, etc.) may be combined with signaling of a dynamic TDD configuration using SIB (SIB1 or another type of SIB).
0132Also, compared to macrocells, UL-DL traffic ratio fluctuations are even more pronounced in small cells (including nanocells, picocells, and femtocells), which have fewer terminals per cell. Therefore, the technique according to the present disclosure is more effective in controlling wireless communication in a small cell in addition to being useful in controlling wireless communication in a macro cell.
0133The series of control processes by each device described herein may be implemented using software, hardware, or any combination of software and hardware. The programs constituting the software are stored in advance in, for example, a storage medium (non-transitory media) provided inside or outside each device. Then, for example, each program is read into RAM (Random Access Memory) at the time of execution and executed by a processor such as a CPU (Central Processing Unit).
0134Although the preferred embodiments of the present disclosure have been described in detail with reference to the accompanying drawings, the technical scope of the present disclosure is not limited to such examples. It is clear that a person having ordinary knowledge in the technical field of the present disclosure can come up with various modifications or modifications within the scope of the technical ideas described in the claims. Of course, it is understood that the above also belongs to the technical scope of the present disclosure.
0135The following configurations also belong to the technical scope of the present disclosure. (1) A communication control device that controls wireless communication performed by one or more terminal devices according to the Time Division Duplex (TDD) system. For each frame containing multiple subframes, a setting unit that sets a link direction configuration that represents the link direction for each subframe, and a setting unit. A control unit that signals the link direction configuration set by the setting unit to each terminal device, With The configuration unit sets the first link direction configuration for the first terminal group and sets the second link direction configuration for the second terminal group. The control unit signals the first link direction configuration to a terminal device belonging to the first terminal group in the first cycle, and in a second cycle shorter than the first cycle, the first cycle. Signaling the second link-direction configuration to terminal devices belonging to the second terminal group, Communication control device. (2) The control unit is SIB (System Information). The image according to (1) above, wherein the first link direction configuration is signaled in (Block) and the second link direction configuration is signaled in a control information region having an update cycle shorter than that of the SIB. Processing equipment. (3) The setting unit selects the second link direction configuration to be set from the set of configurations limited based on the first link direction configuration that has been set, as described in (2) above. Communication control device. (Four) The setting unit As the first link direction configuration, a configuration with a higher uplink rate is set. As the second link directional configuration, a configuration derived by replacing the uplink subframe of the first link directional configuration with a downlink subframe is set. The communication control device according to (3) above. (Five) The communication control device is A scheduling unit that does not allow uplink transmission of terminal devices belonging to the first terminal group for the uplink subframe that is replaced by the downlink subframe in the second link direction configuration. The communication control device according to (4) above. (6) In the scheduling unit, the downlink transmission to the terminal device belonging to the first terminal group is up, and the subframe for ACK / NACK transmission associated with the downlink transmission is up in the second link direction configuration. The communication control device according to (5) above, which schedules only to the subframe designated as the link subframe. (7) The communication control device further includes a storage unit that stores a table that associates the uplink transmission timing with the corresponding uplink permission transmission timing for each configuration candidate. The scheduling unit enters a subframe for transmitting the uplink permission corresponding to the uplink transmission of the terminal device belonging to the first terminal group for the first link direction configuration in the table. Determined by referring to, The communication control device according to (5) or (6) above. (8) The communication control device further includes a storage unit that stores a table that associates the uplink transmission timing with the corresponding ACK / NACK transmission timing for each configuration candidate. The scheduling unit enters a subframe for transmitting the ACK / NACK for the uplink transmission of the terminal device belonging to the first terminal group for the first link direction configuration in the table. Determined by referring to, The communication control device according to (5) or (6) above. (9) The setting unit A configuration with a higher downlink rate is set as the first link direction configuration, and at least one of the downlink subframes of the first link direction configuration is set to the MBSFN (MBMS Single Frequency Network) subframe. Set, As the second link directional configuration, a configuration derived by replacing the MBSFN subframe of the first link directional configuration with an uplink subframe is set. The communication control device according to (3) above. (Ten) The setting unit A dynamic mode in which the second link direction configuration different from the first link direction configuration can be set, and the second link direction configuration same as the first link direction configuration are set. It can operate in both semi-static modes and When the amount of traffic buffered for the first terminal group exceeds the first threshold value during operation in the dynamic mode, the transition to the semi-static mode is performed. The communication control device according to any one of (3) to (7) above. (11) The setting unit transitions to the dynamic mode when the amount of traffic buffered for the first terminal group falls below the second threshold value during operation in the semi-static mode (10). The communication control device according to. (12) The setting unit selects the first link direction configuration and the second link direction configuration to be set for each frame based on the ratio of the traffic volume between the uplink traffic and the downlink traffic. , The communication control device according to any one of (1) to (11) above. (13) The terminal device belonging to the second terminal group has a first operation mode in which the link direction configuration is updated in the first cycle and a second operation in which the link direction configuration is updated in the second cycle. Can operate in both modes, When the ratio of the traffic amount satisfies a predetermined condition, the control unit instructs the terminal device belonging to the second terminal group to switch to the second operation mode. The communication control device according to (12) above. (14) The communication control device is a base station and The base station further comprises a radio communication unit that transmits and receives radio signals according to the second link direction configuration. The communication control device according to any one of (1) to (13) above. (15) The communication control device according to any one of (1) to (13) above, wherein the communication control device is a control node that communicates with the one or more terminal devices via a base station. (16) A communication control method for controlling wireless communication performed by one or more terminal devices according to the Time Division Duplex (TDD) system in a communication control device. For each of the frames containing multiple subframes, setting the first link direction configuration and the second link direction configuration representing the link direction of each subframe, and setting the second link direction configuration. In the first cycle, signaling the first link-direction configuration to a terminal device belonging to the first terminal group, and Signaling the second link-direction configuration to a terminal device belonging to the second terminal group in a second cycle shorter than the first cycle, and Communication control method including. (17) A computer of a communication control device that controls wireless communication performed by one or more terminal devices according to the Time Division Duplex (TDD) scheme. For each frame containing multiple subframes, a setting unit that sets a link direction configuration that represents the link direction for each subframe, and a setting unit. A control unit that signals the link direction configuration set by the setting unit to each terminal device, It is a program to function as The configuration unit sets the first link direction configuration for the first terminal group and sets the second link direction configuration for the second terminal group. The control unit signals the first link direction configuration to a terminal device belonging to the first terminal group in the first cycle, and in a second cycle shorter than the first cycle, the first cycle. Signaling the second link-direction configuration to terminal devices belonging to the second terminal group, program. (18) A wireless communication unit that communicates with a base station using Time Division Duplex (TDD), A control unit that sets the link direction in units of subframes for each of the frames including a plurality of subframes according to the link direction configuration signaled from the base station. It is a terminal device equipped with The control unit has a signaling cycle shorter than the signaling cycle of the first link direction configuration set for the first terminal group, and is set for the second terminal group to which the terminal device belongs. Let the wireless communication unit receive the signaling of the link direction configuration of 2. Terminal equipment. (19) One or more terminal devices that communicate wirelessly according to Time Division Duplex (TDD) schemes, A communication control device that controls the wireless communication performed by the one or more terminal devices, Is a communication control system that includes The communication control device is For each frame containing multiple subframes, a setting unit that sets a link direction configuration that represents the link direction for each subframe, and a setting unit. A control unit that signals the link direction configuration set by the setting unit to each terminal device, With The configuration unit sets the first link direction configuration for the first terminal group and sets the second link direction configuration for the second terminal group. The control unit signals the first link direction configuration to a terminal device belonging to the first terminal group in the first cycle, and in a second cycle shorter than the first cycle, the first cycle. Signaling the second link-direction configuration to terminal devices belonging to the second terminal group, Communication control system.
01361 Communication control system 10 Terminal devices (first terminal group: legacy terminals) 30 Terminals (Second Terminal Group: Dynamic TDD Terminals) 31 Wireless communication unit 33 Control unit 100 Communication controller 110 Wireless communication unit 140 Settings 150 Signaling control unit 160 Scheduling section 170 Memory
31 sheets
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Every citation, both ways
| Document | Relation | Office |
|---|---|---|
| WO2010125769A1 | Cites | World Intellectual Property Organization (WIPO) |
| CATT,TP for TR36.828 section 7,3GPP TSG RAN WG1 Meeting #69 R1-122948,2012年 5月25日,section 7 | Non-patent | – |
| Renesas Mobile Europe Ltd.,Discussion on Enhancements for Dynamic TDD UL-DL Configuration[online], 3GPP TSG-RAN WG1#69 R1-122363,インターネット<URL:http://www.3gpp.org/ftp/tsg_ran/WG1_RL1/TSGR1_69/Docs/R1-122363.zip>,2012年 5月21日 | Non-patent | – |
16 members in 5 offices
Members16
| Document | Office | Kind | |
|---|---|---|---|
| WO2014006994A1 | World Intellectual Property Organization (WIPO) | A1 | |
| CN104396331A | China | A | |
| EP2871900A1 | European Patent Office (EPO) | A1 | |
| US2015156006A1 | United States of America | A1 | |
| EP2871900A4 | European Patent Office (EPO) | A4 | |
| US2016080135A1 | United States of America | A1 | |
| JPWO2014006994A1 | Japan | A1 | |
| US9621328B2 | United States of America | B2 | |
| JP6217634B2 | Japan | B2 | |
| US9825751B2 | United States of America | B2 | |
| JP2017220955A | Japan | A | |
| US2018062822A1 | United States of America | A1 | |
| JP6399178B2This record | Japan | B2 | |
| CN104396331B | China | B | |
| EP2871900B1 | European Patent Office (EPO) | B1 | |
| EP3618556A1 | European Patent Office (EPO) | A1 |
6 legal events, as the office reported them to INPADOC
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Numbers
- Publication
- 6399178
- Application
- 183433
Titles2
- Japanese
- 通信装置、通信方法、プログラム及び端末装置
- English
- Communication equipment, communication methods, programs and terminal equipment
Classification
- CPC, 7
- H04W72/0446
- H04W72/23
- H04L5/14
- H04L1/1854
- H04W72/30
- H04L5/1469
- H04L5/0055
- IPC, 3
- H04W72 04
- H04W28 06
- H04W72 12
