JP2022067963A - Communication system, terminal apparatus, and terminal cooperated reception method - Google Patents

Abstract

To improve reception characteristics while reducing the amount of information requiring relay transmission between terminal apparatuses, in a terminal cooperated MIMO transmission scheme.SOLUTION: In a communication system provided with a plurality of terminal apparatus, each of one or more terminal apparatuses belonging to a first subset of the plurality of terminal apparatuses transmits a MIMO signal received from a base station to one or more terminal apparatuses belonging to a second subset of the plurality of terminal apparatuses; each of the one or more terminal apparatuses belonging to the second subset executes decoding processing for the MIMO signal, obtains a decoded result and a decision value, and transmits the decoded result and the decision value to a destination terminal apparatus among the plurality of terminal apparatuses; and the destination terminal apparatus calculates a final decoded result using the decoded result and the decision value received from the one or more terminal apparatuses belonging to the second subset.SELECTED DRAWING: Figure 1

Description

The present invention relates to a technique for performing MIMO demodulation processing in cooperation with each other in a wireless communication system in which MIMO (Multi-Input Multi-Output) transmission is performed between a base station and a plurality of terminal devices.

MIMO transmission, which uses multiple antennas to perform spatial division and multiplexing on the same wireless channel, has been adopted in various wireless communication systems such as cellular communication systems and wireless LAN systems as a technology for increasing capacity in wireless communication systems. There is.

Generally, in MIMO transmission, by providing an antenna having more than the number of spatial streams to be transmitted by the transmission / reception device, an appropriate MIMO demodulation process is performed on a signal received in a state where a plurality of spatial streams are mixed, and a desired space is desired. It is known that it can receive streams. Therefore, in order to increase the capacity of MIMO transmission, it is necessary to provide as many antennas as possible in both the transmitter / receiver.

However, in reality, there are restrictions on the device, and in particular, the number of antennas that the terminal device can have is limited from the viewpoint of device size and power consumption, so there is a problem that the number of spatial streams that can be transmitted decreases. be.

Therefore, the terminal devices cooperate with each other, and the signal received by the own device is relay-transmitted to the destination terminal device, so that the destination terminal device receives signals as if the number of antennas owned by the own device or more. A "terminal-linked MIMO transmission method" that can expand the capacity of MIMO transmission by performing MIMO demodulation processing using the device has been studied (see, for example, Non-Patent Document 1).

D. Fengning and H. Murata, "Performance Study of Terminal Collaborated MIMO Reception Experimental Testbed in Actual Environment," 2019 IEEE VTS Asia Pacific Wireless Communications Symposium (APWCS), Singapore, 2019, pp. 1-5.

In the terminal-linked MIMO transmission method, it is conceivable to acquire the received signal used for MIMO demodulation for each spatial stream from other peripheral terminal devices and perform MIMO demodulation processing as much as the destination terminal device can demodulate MIMO. Here, if the received signal with poor reception quality is included in the MIMO demodulation, the demodulation performance deteriorates. Therefore, it is desirable to aggregate the number of received signals exceeding the number of spatial streams desired to be demodulated by the destination terminal device.

However, when the number of received signals to be aggregated increases in the destination terminal device, the amount of information required for relay transmission between the terminal devices increases, and it takes a long time to complete the demodulation process.

The present invention has been made in view of the above points, and is a technique capable of improving reception characteristics while reducing the amount of information required for relay transmission between terminal devices in a terminal-linked MIMO transmission method. The purpose is to provide.

According to the disclosed technique, it is a communication system including a plurality of terminal devices.
Each of the one or more terminal devices belonging to the first subset of the plurality of terminal devices transmits the MIMO signal received from the base station to the one or more terminal devices belonging to the second subset of the plurality of terminal devices. ,
Each of one or more terminal devices belonging to the second subset performs a decoding process on the MIMO signal to acquire a decoding result and a determination value, and the decoding result and the determination value are combined with the plurality of terminals. Send to the destination terminal device in the device,
A communication system in which the destination terminal device calculates a final decoding result using the decoding result received from one or more terminal devices belonging to the second subset and the determination value.

According to the disclosed technique, in the terminal-linked MIMO transmission method, a technique capable of improving reception characteristics while reducing the amount of information required for relay transmission between terminal devices is provided.

It is a block diagram of the wireless communication system in embodiment of this invention. It is a figure which shows the functional structure of H-MS, Det-MS, Des-MS. It is a figure which shows the detailed configuration example which concerns on the demodulation processing and the decoding processing of Det-MS. It is a flowchart for demonstrating operation of a wireless communication system in 1st Embodiment. It is a sequence chart for demonstrating the operation of the wireless communication system in 1st Embodiment. It is a flowchart for demonstrating operation of a wireless communication system in 2nd Embodiment. It is a sequence chart for demonstrating the operation of the wireless communication system in 2nd Embodiment. It is a figure which shows the hardware configuration example of the apparatus.

Hereinafter, embodiments of the present invention (the present embodiments) will be described with reference to the drawings. The embodiments described below are merely examples, and the embodiments to which the present invention is applied are not limited to the following embodiments.

The wireless communication system in this embodiment is not limited to a specific method. For example, the wireless communication system in the present embodiment may be a wireless LAN, a system such as LTE or 5G, or a system other than these. Hereinafter, the first embodiment and the second embodiment will be described. The system configuration is the same between the first embodiment and the second embodiment, and there is a difference in their operation.

(First Embodiment)
First, the first embodiment of the present invention will be described.

<System configuration>
FIG. 1 shows a configuration example of the wireless communication system 100 according to the first embodiment. As shown in FIG. 1, the wireless communication system 100 has a base station BS (hereinafter referred to as BS) and a plurality of terminal devices under the BS (hereinafter, the terminal device is referred to as MS).

The BS has a plurality of antennas and has a function of transmitting a plurality of streams of MIMO signals. Each MS has one antenna, and the MSs cooperate with each other by wireless communication and can transmit and receive signals to each other. The MS may be provided with a plurality of antennas. In FIG. 1, the communication of cooperation between MSs is shown as Collaboration links.

MS is classified into one of Helper MS (hereinafter referred to as H-MS) and Detection MS (hereinafter referred to as Det-MS). The H-MS relays the signal received from the BS to the Det-MS, and the Det-MS performs MIMO decoding processing (including demodulation processing) based on the received signal from the BS and the relay signal from the H-MS.

Further, among the plurality of MSs, one or more Destiny MSs (hereinafter referred to as Des-MS) which are destinations of radio signals transmitted by the BS are included, and the Det-MS is a MIMO demodulation processing result (decoding bit string, The residual error coefficient) is relay-transmitted to Des-MS, and Des-MS acquires a decoding bit string based on the relayed MIMO demodulation processing result. Des-MS may also serve as Det-MS or H-MS. When Des-MS is also Det-MS, Des-MS obtains the final decoded bit string by using its own MIMO demodulation processing result and the MIMO demodulation processing result received from another Det-MS.

FIG. 1 shows, as an example for explanation, one BS and six MSs, the BS has four antennas and transmits four spatial stream MIMO signals, and the six MSs have the same. An example is shown in which terminal-linked MIMO reception is performed by receiving a signal.

As shown in FIG. 1, in this example, three units, which are subsets of six MSs, are H-MS (H-MS-1 to 3), and three units of the other subsets are Det-MS (Det). -MS-1 to 3), and one of the three Det-MS (Det-MS-3) is Des-MS.

A plurality of MSs (H-MS, Det-MS, Des-MS) in the present embodiment may have the same configuration, depending on the role (H-MS, Det-MS, Des-MS). May have different configurations. When a plurality of MSs (H-MS, Det-MS, Des-MS) have the same configuration, the operation differs depending on their roles.

<Example of functional configuration of each MS>
FIG. 2 is a diagram showing a functional configuration example (outline configuration example) of each of H-MS, Det-MS, and Des-MS. FIG. 2 shows an example in which Des-MS also serves as Det-MS. As shown in FIG. 2, the H-MS has a signal receiving unit 11 and a signal transmitting unit 12. The Det-MS has a signal receiving unit 21, a decoding processing unit 22, and a data transmitting unit 23. The Des-MS has a data receiving unit 24, a decoding result calculation unit 25, an output unit 26, a Det-MS unit 27, and a data requesting unit 28.

The "signal receiving unit" may be referred to as a "receiving unit", and the "signal transmitting unit" may be referred to as a "transmitting unit". Further, the data request unit 28 of the Des-MS is a functional unit assuming the second embodiment, and the data request unit 28 may not be provided in the first embodiment.

The signal receiving unit 11 of the H-MS receives the signal transmitted from the BS, and the signal transmitting unit 12 transmits the signal by broadcasting. Note that transmission is not limited to broadcasting. For example, it may be multicast.

The Det-MS signal receiving unit 21 receives the signal broadcast from one or more H-MS and the signal transmitted from the BS. The decoding processing unit 22 performs MIMO decoding processing on the signal received by the signal receiving unit 21, and outputs data (decoding bit string) and a residual error coefficient. The data transmission unit 23 transmits the data obtained by the decoding processing unit 22 and the residual error coefficient to Des-MS. This "transmission" includes that the Det-MS unit 27 in the Det-MS that also serves as the Det-MS notifies the decoding result calculation unit 25 of the data and the residual error coefficient.

The Des-MS data receiving unit 24 receives data and a residual error coefficient from one or more Det-MS. The decoding result calculation unit 25 calculates (selects) the final decoding result based on the data output from the Det-MS unit 27 and the residual error coefficient, and the data received by the data receiving unit 24 and the residual error coefficient. )do. The output unit 26 outputs the data selected by the decoding result calculation unit 25.

<Detailed configuration of decoding processing unit 25>
FIG. 3 shows a detailed configuration example of the decoding processing unit 25 in Det-MS. As shown in FIG. 3, the decoding processing unit 25 includes a CP removing unit 102, an S / P conversion unit 103, an FFT unit 104, an MMSE equalization unit 105, an IFFT unit 106, a P / S conversion unit 107, and a BP decoding unit 108. , A soft determination replica generation unit 109 is provided. The outline of the function of each part is as follows.

In the example of FIG. 3, the CP removing unit 102 receives four signals of signal1 (signal 1), signal2 (signal 2), signal3 (signal 3), and signal4 (signal 4). These signals are, for example, a signal relayed and transmitted by the signals received by the three H-MSs from the MS at time k, and a signal received by the Det-MS itself at time k. For example, signal 1 is a signal received from H-MS-1, signal 2 is a signal received from H-MS-2, signal 3 is a signal received from H-MS-3, and signal 4 is a signal received from H-MS-3. It is a signal received by Det-MS.

The CP removal unit 102 removes the cyclic prefix (CP) for each received signal. The S / P conversion unit 103 performs serial / parallel conversion for each signal from which CP has been removed.

The FFT unit 104 performs FFT (Fast Fourier Transform) on the S / P converted signal, and the MMSE equalization unit 105 applies the MMSE filter to the S / P converted signal.

The IFFT unit 106 performs IFF (inverse fast discrete Fourier transform) on the signal to which the MMSE filter is applied, and the P / S conversion unit 107 performs parallel / serial conversion. The BP (Belief Propagation) decoding unit 108 performs BP decoding. The soft determination replica generation unit 109 generates a soft determination replica signal using the value (likelihood) obtained by BP decoding, and feeds back the replica signal to the MMSE filter.

<Example of terminal-linked MIMO transmission flow>
An example of the terminal-linked MIMO transmission flow in the first embodiment having the configuration shown in FIG. 1 will be described according to the flow procedure shown in FIG. The sequence diagram of FIG. 5 is also referred to as appropriate. The step numbers in FIGS. 4 and 5 correspond to each other.

In step S1, the BS transmits a signal (MIMO signal) to the MS. As shown in step S1 of FIG. 5, data for 4 streams is transmitted from the BS as a MIMO signal, and each of the 6 MSs receives the signal transmitted from the BS.

In step S2, each H-MS relays and transmits the signal received from the BS by its own station to the Det-MS. As shown in FIG. 5, each H-MS broadcasts a signal received from the BS.

In addition, each H-MS broadcasts a signal at different timings. In the example of FIG. 5, the H-MS-1 transmits the signal first, the H-MS-2 transmits the signal next, and then the H-MS-3 transmits the signal. Thereby, on the receiving side, it is possible to identify from which H-MS the received signal is the signal broadcast from (and whether the signal is received from the BS) due to the difference in the reception timing.

In step S3, each Det-MS performs MIMO decoding processing by combining the signal relay-transmitted from the H-MS and the signal received from the BS by its own station, and obtains a decoding bit string (also referred to as data) which is a decoding result. Obtain the residual error coefficient. A processing example of the MIMO decoding process and the residual error coefficient will be described later.

In step S4, each Det-MS relays and transmits information on the decoding bit string and the residual error coefficient to the Des-MS. In the example shown in FIG. 5, since Det-MS-3 is Des-MS, Det-MS-3 (Des-MS) has a decoding bit string and a residual error coefficient from Det-MS-1 and Det-MS-2, respectively. Receive information about. Since Det-MS-3 (Des-MS) itself also performs MIMO demodulation processing, the decoding bit string and the residual error coefficient are acquired.

In step S5, Des-MS selects the decoding bit string having the smallest residual error coefficient for each processing block based on the decoding bit string relay-transmitted from each Det-MS and the residual error coefficient, and acquires the final decoding result. ..

The processing block is a bit string that is a unit for Det-MS to perform decoding processing. As an example, Det-MS-3 (Des-MS) receives stream A data, stream B data, stream C data, and stream D data as data of one processing block from Det-MS-1. .. These are collectively referred to as processing block data 1. Further, the Det-MS-3 (Des-MS) receives the data of the stream A, the data of the stream B, the data of the stream C, and the data of the stream D as the data of one processing block from the Det-MS-2. These are collectively referred to as processing block data 2. Further, the data of stream A, the data of stream B, the data of stream C, and the data of stream D acquired by Det-MS-3 (Des-MS) itself are referred to as processing block data 3.

Assuming that the residual error coefficient of the processing block data 1 is 0.1, the residual error coefficient of the processing block data 2 is 0.2, and the residual error coefficient of the processing block data 3 is 0.3, Det-MS-3 (Des). -MS) selects the processing block data 1 having the smallest residual error coefficient as the final decoding result.

It should be noted that the selection of the compound number bit string may be performed not only for each processing block but also for each decoding stream or for the entire decoding bit string other than these. The entire decoding bit string is, for example, a decoding bit string corresponding to the video data having a certain time length when receiving the video data having a certain time length as the decoding bit string.

In the case of selecting each decoded stream, for the sake of explanation, for example, paying attention to the stream A, the Det-MS-3 (Des-MS) is the data (data 1) from the Det-MS-1 to the stream A. ), Received stream A data (referred to as data 2) from Det-MS-2, and Det-MS-3 (Des-MS) itself acquired stream A data (referred to as data 3). And.

Assuming that the residual error coefficient of data 1 is 0.1, the residual error coefficient of data 2 is 0.2, and the residual error coefficient of data 3 is 0, Det-MS-3 (Des-MS) has a residual error coefficient. The data 3 with the smallest is selected as the final decoding result for stream A. The same is true for other streams.

It should be noted that the calculation of the final decoding result using the residual error coefficient is an example. The final decoding result may be calculated using a determination value other than the residual error coefficient.

<Detailed example of MIMO decryption processing>
Next, a detailed example of the MIMO decoding process and the residual error coefficient (which may be called the residual interference coefficient) executed by the decoding processing unit 22 having the configuration shown in FIG. 3 in each Det-MS will be described.

In the present embodiment, the ability to suppress inter-stream interference between terminal devices is enhanced by terminal-linked MIMO reception, and inter-stream interference and inter-symbol interference are suppressed by performing equalization processing in the frequency domain. Further, the transmission sequence is encoded by the LDPC code, and the replica of the interference signal generated from the high-reliability symbol after decoding is subtracted from the reception signal to perform repetitive equalization to suppress the interference signal. As the decoding method of LDPC, BP (Belief Propagation) decoding, which is a repeated decoding method, is used. Hereinafter, a more specific description will be given.

Here, the number of BS antennas in an environment where L (L is a positive integer) delay wave arrives is N (N is a positive integer), and the number of each MS having a single antenna is M (M is). The system model of the wireless communication system 100 in the case of MIMO transmission using a positive integer) unit will be described.

In this case, the signal y (k) [element of the set of the matrix ^{CM × 1} ] received by the MS at the time k is expressed by the following equation (1).

式（１）において、Ｈ（ｌ）［行列Ｃ^Ｍ×Ｎの集合の要素］は第ｌパスの伝搬路行列、ｘ（ｋ）［行列Ｃ^Ｎ×１の集合の要素］、及びｎ（ｋ）［行列Ｃ^Ｍ×１の集合の要素］はそれぞれ時刻ｋにおける送信信号及び雑音信号を表す。

In equation (1), H (l) [element of the set of matrix ^{CM × N} ] is the propagation path matrix of the first path, x (k) [element of the set of matrix ^{CN × 1} ], and n (k). ) [Elements of the set of matrix ^{CM × 1} ] represent the transmission signal and the noise signal at time k, respectively.

Here, the BS transmits a signal in which CP is added to the LDPC-encoded data series. In the MS (Det-MS), the CP removing unit 102 removes the CP from each of the received signal relay-transmitted from the H-MS and its own received signal, and the CP removing unit 102 removes the CP from each of the received signals and the S / P unit for the signal from which the CP has been removed. The FFT unit 104 converts the signal into a signal in the frequency domain via 103.

Then, the MMSE equalization unit 105 executes the MMSE equalization process. In the MMSE equalization process, as shown in the following equations (2) and (3), the MMSE weight W (f) [elements of the set of the matrix ^{CM × N} ] is used for the initial equalization, so that the f is f. Signals X ^to (f) [elements of a set of matrices ^{CN × 1} ] after equalization of frequency components are obtained.

ここで、Ｇ（ｆ）［行列Ｃ^Ｍ×Ｎの集合の要素］及びＹ（ｆ）［行列Ｃ^Ｍ×１の集合の要素］はそれぞれ第ｆ周波数成分における伝搬路応答及び受信信号であり、Ｎは雑音電力、Ｐは送信電力である。

Here, G (f) [element of the set of matrix ^{CM × N} ] and Y (f) [element of the set of matrix ^{CM × 1} ] are the propagation path response and the received signal in the fth frequency component, respectively. N is noise power and P is transmission power.

Then, the likelihood is calculated from the signals x ^to (k) [elements of the set of the matrix ^{CN × 1} ] converted into the time domain by the IFFT unit 106 after the MMSE equalization, and that is the input value to the BP decoding unit 108. Then, the BP decoding unit 108 performs BP decoding.

Then, when the upper limit of the iterative equalization process set in advance has not been reached, the soft determination replica generation unit 109 uses the soft determination symbol x ^ (k) [matrix ^{CN × 1} from the likelihood updated after BP decoding. ^Elements of the set of Using the frequency response vector g _n (f) [element of the set of matrix ^{CM × 1} ] for the transmitting antenna, the soft determination replica of the interference signal Y ^ _n (f) [element of matrix ^{CM × 1} ] is expressed by the following equation. Generated by (4).

２回目以降の繰り返し等化時におけるＭＭＳＥ等化部１０５は、受信信号Ｙ（ｆ）から所望信号以外のすべての干渉信号のレプリカを減算した後、ウェイトを掛け合わせることにより等化処理を行う。ここで、所望の空間ストリームの信号が第ｎ信号（ｉ＝ｎ）であるとき、ＭＭＳＥ等化後の出力Ｘ^～ _ｎ（ｆ）は下記の式（５）となる。なお、ｉは空間ストリームの番号であり、ｉ≠ｎの空間ストリームの信号は干渉信号となる。

The MMSE equalization unit 105 at the time of the second and subsequent repeated equalization performs the equalization process by subtracting the replicas of all the interference signals other than the desired signal from the received signal Y (f) and then multiplying them by the waits. Here, when the signal of the desired spatial stream is the nth signal (i = n), the outputs X ^to _n (f) after MMSE equalization are given by the following equation (5). Note that i is the number of the spatial stream, and the signal of the spatial stream of i ≠ n is an interference signal.

ここで、ウェイトｗ_ｎ（ｆ）は、上記の式（６）で表される。

Here, the weight w _n (f) is expressed by the above equation (6).

In the equation (6), β _i is a residual error coefficient satisfying 0 ≦ β _i ≦ 1, and represents the magnitude of residual interference. For example, if there is no residual interference (residual error), β _i = 0.

For example, if the parity check of the decoding bit string obtained by the rigid determination is successful, it can be determined that there is no residual interference, and β _i = 0. If the parity check is not successful, β _i may be calculated by the following equation (7), for example.

β _i = 1- (1 / K) × Σ _k | x ^ _i (k) | .... (7)
k is the kth symbol of the received signal, and K is the total number of symbols. x ^ _i (k) is a soft determination symbol for the spatial stream i, and Σ _k indicates the sum from 1 to K.

The residual error coefficient obtained by the above equation (7) is a residual error coefficient in a stream unit, and the above β _i can be used when the decoding bit string is selected in the stream unit as described above.

When the decoding bit string is selected for each processing block, for example, the sum β of the residual error coefficients of all the streams calculated by the following equation (8) can be used as the residual error coefficient.

β = Σ _i β _i .... (8)
The method for calculating the residual error coefficient described above is an example, and the residual error coefficient may be obtained by a calculation method other than the above calculation method.

The outputs X ^to _n (f) after the MMSE equalization are converted into time domain signals x ^to _n (k) by the IFFT unit 106, and again input to the BP decoding unit 108 to update the likelihood of the soft determination replica. It is output to the generation unit 109, and the equalization process is repeatedly performed. Then, when the iterative equalization process is completed, the rigidity of the BP decoding unit 108 is determined to be rigid, and the result of the hardness determination (0 or 1) is output as the final decoding bit string.

<Effect of the first embodiment>
As described above, the MS (H-MS) relays and transmits the signal received from the BS to another MS (Det-MS) by broadcast communication, and performs MIMO decoding processing on a plurality of Det-MS. It was decided to aggregate in Des-MS and Des-MS would select the optimum data. This makes it possible to improve the reception characteristics in the terminal-linked MIMO transmission method while reducing the amount of information that requires relay transmission between MSs.

(Second Embodiment)
Next, the second embodiment will be described. The system configuration example and the MIMO decoding processing procedure example of the second embodiment are the same as those of the first embodiment, and are as described with reference to FIGS. 1 to 3 and the like. Hereinafter, the points different from the first embodiment will be mainly described.

FIG. 6 shows an example of a terminal-linked MIMO transmission flow according to the second embodiment. An example of the terminal-linked MIMO transmission flow in the second embodiment will be described according to the flow procedure shown in FIG. The sequence diagram of FIG. 7 is also referred to as appropriate. The step numbers in FIGS. 6 and 7 correspond to each other.

Steps S1 to S3 are the same as steps S1 to S3 of the first embodiment.

In step S6, Des-MS performs determination processing based on the MIMO decoding result (decoding bit string, residual error coefficient) of its own station, determines whether or not there is a decoding bit string that requires additional acquisition, and additional acquisition is required. If there is a decryption bit string, select the decryption bit string. As shown in FIG. 7, in this example, Det-MS-3 (Des-MS) performs this process. Here, the decoding bit string to be selected may be in units of streams to be decoded or in units of processing blocks.

In step S7, the data requesting unit 27 of Des-MS requests each Det-MS other than itself to relay and transmit the decoding result of the decoding result selected in step S6. As shown in FIG. 7, in this example, Det-MS-3 (Des-MS) makes this request to Det-MS-1 and Det-MS-2.

In step S8, each Det-MS that receives the request relays and transmits the requested MIMO decoding result and the residual error coefficient to Des-MS. As shown in FIG. 7, in this example, Det-MS-1 and Det-MS-2 transmit data (decoding result) to Det-MS-3 (Des-MS).

In step S9, Des-MS selects the decoding bit string having the smallest residual error coefficient for each processing block (or stream) based on the decoding bit string relay-transmitted from each Det-MS and the residual error coefficient, and finally. Get the decryption result.

A specific example of the process will be described. As an example of the case where selection is performed in stream units, in the stage before step S6, Det-MS-3 (Des-MS) uses the data of stream A (referred to as data A) and its residual error coefficient = 0. Stream B data (referred to as data B) and its residual error coefficient = 0, stream C data (referred to as data C) and its residual error coefficient = 0, stream D data (referred to as data D) and its residual error It is assumed that the coefficient = 0.5 is acquired.

In this case, in step S6, the decoding result calculation unit 25 of Det-MS-3 (Des-MS) selects the data D, and in step S7, the data D is relative to Det-MS-1 and Det-MS-2. (Decoding bit string of stream D) and its residual error coefficient are requested. For example, a threshold value of the residual error coefficient may be determined in advance, and data having a residual error coefficient equal to or higher than the threshold value may be determined as the target of the request. If there is no data having a residual error coefficient greater than or equal to the threshold value, the request is not made.

In step S8, Det-MS-1 and Det-MS-2 each transmit data D (decoding bit string of stream D) and its residual error coefficient to Det-MS-3 (Des-MS).

Here, the residual error coefficient of the data D (decoded bit string of the stream D) received from Det-MS-1 is 0, and the residual error coefficient of the data D (decoded bit string of the stream D) received from Det-MS-2. Is 0.1, in step S9, Det-MS-3 (Des-MS) has the smallest of 0.5, 0, and 0.1 as the residual error coefficient, Det-. The data D (decoding bit string of stream D) received from MS-1 is selected as the final decoding bit string of stream D.

Regarding the case of selecting in units of processing blocks, as an example, in the stage before step S6, Det-MS-3 (Des-MS) has acquired the processing block data 1 and its residual error coefficient = 0.5. do.

In this case, in step S6, the decoding result calculation unit 25 of Det-MS-3 (Des-MS) selects the processing block data 1, and in step S7, with respect to Det-MS-1 and Det-MS-2. The processing block data 1 (data of the corresponding block) and its residual error coefficient are requested. For example, a threshold value of the residual error coefficient may be determined in advance, and data having a residual error coefficient equal to or higher than the threshold value may be determined as the target of the request.

In step S8, Det-MS-1 and Det-MS-2 transmit the processing block data 1 and its residual error coefficient to Det-MS-3 (Des-MS), respectively.

Here, the residual error coefficient of the processing block data 1 (corresponding block data) received from Det-MS-1 is 0, and the processing block data 1 (corresponding block data) received from Det-MS-2 has a residual error coefficient of 0. Assuming that the residual error coefficient of (data)) is 0.1, in step S9, Det-MS-3 (Des-MS) retains 0, which is the smallest of 0.5, 0, and 0.1. The processing block data 1 (data of the corresponding block) received from Det-MS-1 having an error coefficient is selected as the decoding bit string of the processing block data 1.

<Effect of the second embodiment>
In the second embodiment, the relay transmission amount between Det-MS and Des-MS can be reduced as compared with the first embodiment.

(Hardware configuration example)
Both the BS and MS in the present embodiment may be realized entirely by dedicated hardware (multiple LSIs, etc.), or parts other than the transmission / reception unit (antenna, RF unit, etc.) that performs analog processing (that is,). , The part that processes digital signals) may be realized by a general-purpose computer including a processor (CPU, DSP, etc.) and a memory, and software running on the computer.

FIG. 8 shows a configuration example of the device 200 in the case of realizing BS or MS (collectively referred to as a device) using a computer and software.

As shown in FIG. 8, the device 200 includes a processor 201, a memory 202, an auxiliary storage device 203, an input / output device 204, and a transmission / reception unit 205, and has a configuration in which these are connected by a bus.

For example, the auxiliary storage device 203 stores a program that realizes the operation of the device 200. Further, the program may be stored in the auxiliary storage device 203 from a computer-readable recording medium or from a server on the network via the network.

During the operation of the device 200, the program is read into the memory 202, and the processor 201 reads the program from the memory 202 and executes it. For example, when the device 200 is an MS, the processor 201 executes the above-mentioned MIMO decoding process, decoding result selection process, and the like. The input / output device 104, for example, inputs / outputs data.

The "computer-readable recording medium" refers to a portable medium such as a flexible disk, a magneto-optical disk, a ROM, or a CD-ROM, or a storage device such as a hard disk built in a computer system. Further, a "computer-readable recording medium" is a communication line for transmitting a program via a network such as the Internet or a communication line such as a telephone line, and dynamically holds the program for a short period of time. It may also include a program that holds a program for a certain period of time, such as a volatile memory inside a computer system that is a server or a client in that case. Further, the above program may be for realizing a part of the above-mentioned functions, and may be further realized for realizing the above-mentioned functions in combination with a program already recorded in the computer system. It may be realized by using hardware such as PLD (Programmable Logic Device) or FPGA (Field Programmable Gate Array).

(Effect of embodiment)
In the technique according to the present embodiment, the H-MS relays and transmits the signal received from the BS to the Det-MS by broadcast communication, and performs MIMO decoding processing on the plurality of Det-MS to the Des-MS. By aggregating, it is possible to improve the reception characteristics in the terminal-linked MIMO transmission method while reducing the amount of information required for relay transmission between MSs.

(Summary of embodiments)
This specification describes at least the communication system, the terminal device, and the terminal cooperation receiving method described in each of the following items.
(Section 1)
A communication system equipped with multiple terminal devices,
Each of the one or more terminal devices belonging to the first subset of the plurality of terminal devices transmits the MIMO signal received from the base station to the one or more terminal devices belonging to the second subset of the plurality of terminal devices. ,
Each of one or more terminal devices belonging to the second subset performs a decoding process on the MIMO signal to acquire a decoding result and a determination value, and the decoding result and the determination value are combined with the plurality of terminals. Send to the destination terminal device in the device,
A communication system in which the destination terminal device calculates a final decoding result using the decoding result received from one or more terminal devices belonging to the second subset and the determination value.
(Section 2)
The communication system according to item 1, wherein each of the one or more terminal devices belonging to the first subset transmits the MIMO signal to the one or more terminal devices belonging to the second subset by broadcasting.
(Section 3)
The determination value is a residual error coefficient of the weight used in the MIMO equalization process.
The communication system according to item 1 or 2, wherein the destination terminal device selects a decoding result having the minimum residual error coefficient from one or more decoding results as the final decoding result.
(Section 4)
A communication system equipped with multiple terminal devices,
Each of the one or more terminal devices belonging to the first subset of the plurality of terminal devices transmits the MIMO signal received from the base station to the one or more terminal devices belonging to the second subset of the plurality of terminal devices. ,
The destination terminal device belonging to the second subset performs a decoding process on the MIMO signal, acquires a decoding result and a determination value, and based on the determination value, another terminal belonging to the second subset. A communication system that determines whether to request a decryption result from a device.
(Section 5)
When the destination terminal device determines that the request is to be made, the destination terminal device makes a request to another terminal device belonging to the second subset by designating a decoding result of a specific unit, and makes a request to the second subset. The communication system according to Item 4, wherein the decoding result and the determination value of the specific unit are acquired from another terminal device to which the terminal device belongs.
(Section 6)
A terminal device in a communication system including a plurality of terminal devices.
A receiving unit that receives MIMO signals received from a base station from each of one or more terminal devices belonging to a subset of the plurality of terminal devices.
A terminal including a transmission unit that performs decoding processing on the MIMO signal, acquires a decoding result and a determination value, and transmits the decoding result and the determination value to a destination terminal device among the plurality of terminal devices. Device.
(Section 7)
A terminal device in a communication system including a plurality of terminal devices.
A receiving unit that receives MIMO signals received from a base station from each of one or more terminal devices belonging to a subset of the plurality of terminal devices.
A decoding result calculation unit that performs decoding processing on the MIMO signal, acquires the decoding result and the determination value, and determines whether or not to request the decoding result from another terminal device based on the determination value. A terminal device to be equipped.
(Section 8)
It is a terminal-linked receiving method executed in a communication system equipped with a plurality of terminal devices.
Each of the one or more terminal devices belonging to the first subset of the plurality of terminal devices transmits the MIMO signal received from the base station to the one or more terminal devices belonging to the second subset of the plurality of terminal devices. ,
Each of one or more terminal devices belonging to the second subset performs a decoding process on the MIMO signal to acquire a decoding result and a determination value, and the decoding result and the determination value are combined with the plurality of terminals. Send to the destination terminal device in the device,
A terminal cooperation receiving method for calculating a final decoding result by using the decoding result and the determination value received by the destination terminal device from one or more terminal devices belonging to the second subset.

Although the present embodiment has been described above, the present invention is not limited to such a specific embodiment, and various modifications and changes can be made within the scope of the gist of the present invention described in the claims. It is possible.

MS terminal device BS base station 11 signal receiving unit 12 signal transmitting unit 21 signal receiving unit 22 decoding processing unit 23 data transmitting unit 24 data receiving unit 25 decoding result calculation unit 26 output unit 27 Det-MS unit 28 data requesting unit 201 processor 202 Memory 203 Auxiliary storage device 204 Input / output device 205 Transmission / reception unit

Claims (8)

A communication system equipped with multiple terminal devices,
Each of the one or more terminal devices belonging to the first subset of the plurality of terminal devices transmits the MIMO signal received from the base station to the one or more terminal devices belonging to the second subset of the plurality of terminal devices. ,
Each of one or more terminal devices belonging to the second subset performs a decoding process on the MIMO signal to acquire a decoding result and a determination value, and the decoding result and the determination value are combined with the plurality of terminals. Send to the destination terminal device in the device,
A communication system in which the destination terminal device calculates a final decoding result using the decoding result received from one or more terminal devices belonging to the second subset and the determination value. The communication system according to claim 1, wherein each of the one or more terminal devices belonging to the first subset transmits the MIMO signal to the one or more terminal devices belonging to the second subset. The determination value is a residual error coefficient of the weight used in the MIMO equalization process.
The communication system according to claim 1 or 2, wherein the destination terminal device selects a decoding result having the minimum residual error coefficient from one or more decoding results as the final decoding result. A communication system equipped with multiple terminal devices,
Each of the one or more terminal devices belonging to the first subset of the plurality of terminal devices transmits the MIMO signal received from the base station to the one or more terminal devices belonging to the second subset of the plurality of terminal devices. ,
The destination terminal device belonging to the second subset performs a decoding process on the MIMO signal, acquires a decoding result and a determination value, and based on the determination value, another terminal belonging to the second subset. A communication system that determines whether to request a decryption result from a device. When the destination terminal device determines that the request is to be made, the destination terminal device makes a request to another terminal device belonging to the second subset by designating a decoding result of a specific unit, and makes a request to the second subset. The communication system according to claim 4, wherein the decoding result and the determination value of the specific unit are acquired from another terminal device to which the terminal device belongs. A terminal device in a communication system including a plurality of terminal devices.
A receiving unit that receives MIMO signals received from a base station from each of one or more terminal devices belonging to a subset of the plurality of terminal devices.
A terminal including a transmission unit that performs decoding processing on the MIMO signal, acquires a decoding result and a determination value, and transmits the decoding result and the determination value to a destination terminal device among the plurality of terminal devices. Device. A terminal device in a communication system including a plurality of terminal devices.
A receiving unit that receives MIMO signals received from a base station from each of one or more terminal devices belonging to a subset of the plurality of terminal devices.
A decoding result calculation unit that performs decoding processing on the MIMO signal, acquires the decoding result and the determination value, and determines whether or not to request the decoding result from another terminal device based on the determination value. A terminal device to be equipped. It is a terminal-linked receiving method executed in a communication system equipped with a plurality of terminal devices.
Each of the one or more terminal devices belonging to the first subset of the plurality of terminal devices transmits the MIMO signal received from the base station to the one or more terminal devices belonging to the second subset of the plurality of terminal devices. ,
Each of one or more terminal devices belonging to the second subset performs a decoding process on the MIMO signal to acquire a decoding result and a determination value, and the decoding result and the determination value are combined with the plurality of terminals. Send to the destination terminal device in the device,
A terminal cooperation receiving method for calculating a final decoding result by using the decoding result and the determination value received by the destination terminal device from one or more terminal devices belonging to the second subset.

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