JP4812779B2 - Mobile communication system, communication method therefor, and transmission station - Google Patents

Description

  The present invention relates to a mobile communication system, a communication method therefor, and a transmission station, and more particularly to a mobile communication system including a plurality of transmission antennas and reception antennas and capable of high-speed data transfer, a communication method therefor, and a transmission station.

In today's wireless communication systems, attention is paid to a spatial multiplexing transmission technique that increases transmission capacity in proportion to the number of transmission antennas by transmitting different data streams in parallel from a plurality of transmission antennas. Different transmission antennas are arranged so as to be uncorrelated with each other, and data streams transmitted from the respective antennas are received by reception antennas through independent fading propagation paths.
Here, a multiple-input multiple-output (MIMO) system using a plurality of receiving antennas arranged so as to be uncorrelated with each other provides a highly flexible channel correlation. A matrix can be generated, and an SNR when separating a spatially multiplexed data stream can be improved.
FIG. 14 shows the configuration of the MIMO system, where TR is a transmitting station and RV is a receiving station. The same number of data streams S _{1 to} S _M as the number _M of transmitting antennas ATT _{1 to} ATTM is transmitted by each transmitter TX _{1 to} TX _M for data modulation, oversampling, D / A conversion, quadrature modulation, and frequency up-conversion. - zone via limiting filtering process such as is transmitted from each transmit antenna ATT ₁ ~ATT _M. A signal transmitted from each antenna ATT _{1 to} AT _M passes through an independent fading channel h _mn (m = 1 to M, n = 1 to N), and is multiplexed in space, and then N receiving antennas ATR ₁ ~ Received at ATR _N Signals received by the receiving antennas are subjected to filtering, frequency down-conversion, quadrature detection, and A / D conversion processing in the reception units RX _{1 to} RX _N , and x ₁ to x _N received data streams are generated. Since each reception data stream has a form in which M transmission data streams are multiplexed, the transmission data stream is separated and reproduced by performing signal processing on all reception data streams.
15 and 16 are configuration examples of a receiver and a transmitter in a conventional digital wireless communication system that does not include a MIMO system. The ranges of the transmission units (TX _{1 to} TX _M ) and the reception units (RX _{1 to} RX _N ) shown in FIG. 14 are indicated by being surrounded by dotted lines as TX and RX in FIGS. 15 and 16. In the preceding stage of the transmission unit TX (FIG. 15), transmission data is encoded according to a predetermined encoding method, and the encoded data is mapped to two orthogonal axes I and Q according to a modulation method (QPSK, 16QAM, 64QAM, etc.). . Next, the transmission data is time-multiplexed with the pilot, and thereafter transmitted from the transmission antenna ATT through processes such as oversampling, D / A conversion, orthogonal modulation, frequency up-conversion, and band-limited filtering.
The receiving unit RX (FIG. 16) performs filtering, frequency down-conversion, quadrature detection, and A / D conversion processing. Thereafter, channel estimation, synchronous detection, data demodulation (demapping), and data decoding processing are performed.

ここで、Ｅはアンサンブル平均、HはN×Mの複素チャネル行列(h₁₁〜h_MN)であり、Vは分散σ_Vで平均値0の複素白色雑音行列である。^*は、行列の複素共役転置を表す。また、IはN次元の単位行列である。
ZFアルゴリズムでは、次式により送信データストリームを推定する。

ここで、H^*Hはチャネル相関行列と呼ばれる。チャネル相関行列の逆行列が存在するためには、N≧Mの関係が必要になる。
MMSEアルゴリズムでは、次式により送信データストリームを推定する。

ここで、ρは、受信アンテナ当りのSNRに相当する。MMSEではSNRを精度よく推定する必要が生じるが、ZFにおける雑音強調の影響を低減することができるため、一般にZFより特性が優れている。
MLDアルゴリズムでは、次式により送信データストリームを推定する。

ここで、Qは変調データの信号点配置の数で、QPSKでQ=4, 16QAMでQ=16, 64QAMでQ=64となる。このように、MLDでは、多値変調の演算量が膨大となり、かつ演算量は送信アンテナ数に対して指数関数的に増大してしまう。なお、MLDでは、チャネル相関行列の逆行列演算を必要としないため、N≧Mの関係は不要である。
BLASTアルゴリズム関しては、後述の非特許文献１、２に詳しく記述されているので、説明は省略する。 The signal processing algorithm of the data processing apparatus DPU that separates the transmission data streams S _{1 to} S _M (FIG. 14) from the received signal includes linear algorithms such as ZF (Zero-Forcing) and MMSE using an inverse matrix of the channel correlation matrix. There are non-linear algorithms represented by BLAST (Bell Laboratories Layered Space-Time). Also known is a method that does not use an inverse matrix operation of a correlation matrix such as MLD (Maximum Likelihood Decoding).
Now, when the transmission data stream is represented by an M-dimensional complex matrix S and the reception data stream is represented by an N-dimensional complex matrix X, the following relationship is established.

Here, E is an ensemble average, H is an N × M complex channel matrix (h _{11 to} h _MN ), and V is a complex white noise matrix with variance σ _V and average value 0. ^* Represents the complex conjugate transpose of the matrix. I is an N-dimensional unit matrix.
In the ZF algorithm, a transmission data stream is estimated by the following equation.

Here, H ^* H is called a channel correlation matrix. In order to have an inverse matrix of the channel correlation matrix, a relationship of N ≧ M is necessary.
In the MMSE algorithm, a transmission data stream is estimated by the following equation.

Here, ρ corresponds to the SNR per receiving antenna. In MMSE, it is necessary to accurately estimate the SNR, but since the influence of noise enhancement in ZF can be reduced, the characteristics are generally superior to those of ZF.
In the MLD algorithm, a transmission data stream is estimated by the following equation.

Here, Q is the number of constellation points of the modulation data, Q = 4 for QPSK, Q = 16 for 16QAM, and Q = 64 for 64QAM. Thus, in MLD, the amount of computation of multi-level modulation becomes enormous, and the amount of computation increases exponentially with respect to the number of transmission antennas. Note that MLD does not require an inverse matrix operation of the channel correlation matrix, and therefore the relationship of N ≧ M is not necessary.
Since the BLAST algorithm is described in detail in Non-Patent Documents 1 and 2 described later, the description thereof is omitted.

毎に誤り検出を行い、ACK/NACK発生部ANGはデータストリーム毎にエラー検出結果（ACK/NACK）を逆方向の無線リンク(送信部TX,送信アンテナATT、受信アンテナATR、受信部RX)を用いて、送信局TRに通知する。送信局TRの再送制御部RTCは、管理する再送バッファRTB₁〜RTB_Mの中から、NACKに該当するデータストリームの再送を行う。この時、送信に使用するアンテナは固定である。すなわち、再送も前回の送信と同一アンテナを用いて行われる。
MIMOシステムにおいて再送制御を行う場合、再送パケットを同一のアンテナから送信すると、伝送路状態の悪いアンテナを使い続けることになるため、再送による誤り率の改善が小さくなり、再送制御の利得が得られにくくなるといった問題が生じる。特に、フェージングやマルチパス環境の変化が、再送間隔（Round Trip Time）に比べて遅い場合に、この問題は深刻である。 In general, in a MIMO system, a transmission error is likely to occur in a data stream transmitted from an antenna whose propagation path state is worse than that of other transmission antennas. Since such an antenna having a poor propagation path state changes due to fading fluctuation, a data stream causing a transmission error also changes with time. Also, in a MIMO system, transmission errors are likely to occur even when the correlation between antennas becomes high due to the propagation environment. Specifically, in the multipath propagation path, when there is a particularly high power path such as a direct wave or a strong reflected wave, the correlation between the antennas becomes high. Since the state of the propagation path changes in a complicated manner, a case where a transmission error occurs in a specific data stream occurs due to a high correlation between specific antennas. The state of the antenna correlation as described above also changes from moment to moment due to movement of the receiving station and changes in the surrounding environment.
Thus, in a MIMO system, errors tend to concentrate on a specific data stream, and the data stream on which errors are concentrated changes with time. By the way, in high-speed wireless data communication, it is indispensable to apply retransmission control in a wireless section such as ARQ (Automatic Repeat reQuest). FIG. 17 shows a conventional example when retransmission control is applied in a MIMO system, and the same parts as those in FIG. The data stream multiplexed in space is separated by the signal processing of the data processing device DPU, demodulated / decoded by the data demodulation / decoding unit RDU, and input to the error detection unit EDT. Error detector EDT is a data stream

ACK / NACK generator ANG sends the error detection result (ACK / NACK) for each data stream to the reverse radio link (transmitter TX, transmit antenna ATT, receive antenna ATR, receiver RX). To notify the transmitting station TR. Retransmission controller RTC of the transmitting station TR, from the retransmission buffer RTB ₁ ~RTB _M that manages, retransmits the data stream corresponding to NACK. At this time, the antenna used for transmission is fixed. That is, retransmission is also performed using the same antenna as the previous transmission.
When performing retransmission control in a MIMO system, if a retransmission packet is transmitted from the same antenna, an antenna with a poor transmission path condition will continue to be used, so the improvement in error rate due to retransmission will be small and a gain for retransmission control will be obtained. The problem of becoming difficult arises. This problem is particularly serious when fading and changes in the multipath environment are slower than the retransmission interval (Round Trip Time).

There is (Patent Document 1) as the first conventional technique of the MIMO system. In this first prior art, the receiver of the MIMO system detects the rate and power of each data stream and feeds back to the transmitter, and the transmitter uses the rate and power of the corresponding data stream based on the fed back rate and power. Control power to improve throughput. However, this first prior art does not improve the error rate due to retransmission.
As a second prior art of the MIMO system, there is (Patent Document 2). In this second prior art, (1) the transmitter creates and transmits at least two error-coded streams from the information block, and the receiver performs error checking for each stream, and if an error is detected, an error is detected. (2) The transmitter creates and transmits at least two error encoded streams from the information block, and the receiver synthesizes each error encoded stream to generate an error. If an error is detected, retransmission of each error encoded stream is requested. The second prior art relates to retransmission control, but does not improve the error rate due to retransmission and does not improve retransmission efficiency.
GJFoschini, "Layered Space-Time Architecture for Wireless Communication in a Fading Environment When Using Multi-Element Antennas," Bell Laboratories Technical Journal, vol.1, no.2, pp.41-59, 1996 PWWolniansky, GJFoschini, GDGolden, RAValenzuela, "V-BLAST: An Architecture for Realizing Very High Data Rates Over the Rich-Scattering Wireless Channel," in Proc.ISSSE-98, Italy, Sept. 1998 Japanese Patent Laid-Open No. 2002-217752 Japanese Patent Laid-Open No. 2003-124915

  As described above, there is no conventional technique for preventing a reduction in error rate improvement caused by continuing to use an antenna having a poor transmission path state in the retransmission control of the MIMO system. Therefore, an object of the present invention is to improve an error rate due to retransmission and improve retransmission efficiency in a MIMO system.

-Communication method in mobile communication system The communication method of the present invention is a mobile capable of simultaneously transmitting a plurality of data streams from a transmitting station having a plurality of antennas to a receiving station having a plurality of antennas using a MIMO scheme. A communication method in a communication system, wherein a first data stream out of a first data stream and a second data stream simultaneously transmitted from each of a first antenna and a second antenna of the transmitting station When the second data stream is normally received at the receiving station and the second data stream cannot be normally received at the receiving station, retransmission of the second data stream is performed using the first antenna and the second antenna . To do.
-Mobile communication system The mobile communication system of the present invention is a mobile communication system capable of simultaneously transmitting a plurality of data streams from a transmitting station having a plurality of antennas to a receiving station having a plurality of antennas using a MIMO scheme. The transmitting station includes an allocating unit that allocates data so as to transmit the first data stream and the second data stream from each of the first antenna and the second antenna, and the receiving station includes: When the first data stream of the first data stream and the second data stream is normally received at the receiving station, and the second data stream cannot be normally received at the receiving station. A transmission unit for transmitting a reception result of the first data stream and the second data stream to the transmission station, The allocating unit performs allocation so that transmission is performed using the first antenna and the second antenna when the second data stream is retransmitted according to the reception result.
-Transmitting station The transmitting station of the present invention transmits a mobile communication system capable of simultaneously transmitting a plurality of data streams using a MIMO scheme from a transmitting station having a plurality of antennas to a receiving station having a plurality of antennas. Data transmitted from the first antenna, the second antenna, the first antenna, and the second antenna, each of which transmits a data stream, respectively, from the first antenna and the second antenna. Of the first data stream and the second data stream, the first data stream is normally received at the receiving station, and the second data stream is normal at the receiving station. A receiving unit that receives from the receiving station a reception result indicating that the signal could not be received, and the allocating unit responds to the reception result. Then, when retransmitting the second data stream, allocation is performed so that transmission is performed using the first antenna and the second antenna .

According to the present invention, it is possible to improve an error rate of data and improve retransmission efficiency.
Also, according to the present invention, when retransmission control is performed in a MIMO system, transmission can be successful with a small number of retransmissions, and retransmission efficiency can be improved.

In a mobile communication system capable of simultaneously transmitting a plurality of data streams using a MIMO scheme from a transmitting station having a plurality of antennas to a receiving station having a plurality of antennas, the first antenna of the transmitting station, Of the first data stream and the second data stream transmitted simultaneously from each of the two antennas, the first data stream is normally received by the receiving station, and the second data stream is received by the receiving station. If the second data stream cannot be normally received, the second data stream is retransmitted using the first antenna.
Alternatively, the transmitting station transmits a data stream having the same content from each of the plurality of antennas from a mode in which the plurality of data streams according to the MIMO scheme are simultaneously transmitted to the receiving station using the plurality of antennas. Switch to the retransmission mode.
Alternatively, the transmitting station distributes one data stream to a plurality of streams from a mode in which a plurality of data streams according to the MIMO scheme are simultaneously transmitted to the receiving station using the plurality of antennas, and The mode is switched to a retransmission mode in which the plurality of streams are simultaneously transmitted to the receiving station by the MIMO scheme.
With the above control, when performing retransmission control in a MIMO system, it is possible to improve the error rate of data transmitted from an antenna having a bad propagation path condition last time and improve retransmission efficiency. Also, when performing retransmission control in a MIMO system, transmission can be successfully performed with a small number of retransmissions, and retransmission efficiency can be improved.

毎に誤り検出を行い、ACK/NACK発生部ANGはデータストリーム毎にエラー検出結果（ACK/NACK）を逆方向の無線リンク(送信部TX,送信アンテナATT、受信アンテナATR、受信部RX)を用いて、送信局に通知する。
伝搬路推定部TPEは、チャネル推定結果h₁₁〜h_MNを用いて、送信アンテナ毎の伝搬路状態（受信電力SあるいはSIR）を推定する。例えば、伝搬路推定部TPEは、送信アンテナATTi（ｉ＝１〜Ｍ）の受信電力Siを次式

により推定す。アンテナ選択部ATSは、伝搬路情報およびACK/NACK情報を基に、再送に用いる送信アンテナを決定する。再送に用いる送信アンテナとしては、電力Siが大きい、すなわち伝搬路状態が良好なアンテナを選択する。再送に用いる送信アンテナの情報(アンテナ番号)は、ACK/NACK情報と共に、逆リンク（受信局→送信局）における制御チャネルによって、送信局に通知される。また、再送に用いる送信アンテナ情報(アンテナ番号)は、データ処理部DPUにも通知され、再送のデータストリームの分離のために使用される。
送信局TRの再送制御部RTCは、受信局RVから通知されたACK/NACK情報に基づいて再送バッファRTB₁〜RTB_Mの中から、NACKに該当するデータストリームを読み出してアンテナ割当部AALに入力する。アンテナ割当部AALは、該入力された再送用のデータストリームを、受信局から通知されたアンテナ番号が示す送信アンテナに入力する。以上により、再送は伝搬状態が良好な送信アンテナより行われる。
図4はアンテナ選択部ATSによる再送用の送信アンテナ決定処理フローであり、以降のいずれの実施例においても採用することができる。
まず、伝搬路状態の良い順に送信アンテナをランキング付けする(ステップ101)。ついで、NACKとなったデータストリームを、その送信アンテナの伝搬路状態が悪い順に並べる(ステップ102)。しかる後、ｉ＝１とし(ステップ103)、第ｉ番目のデータストリームを第ｉランクの送信アンテナに割り当てる(ステップ104)。これにより、ｉ＝１であれば、最も伝搬路状態の悪い送信アンテナより送信されてNACKとなったデータストリームを最も伝搬路状態が良い送信アンテナに割り当てて再送することができる。
ついで、全部の再送用のデータストリームの割当が完了したかチェックし(ステップ105)、完了してなければｉを歩進し(ステップ106)、ステップ104以降の処理を繰り返す。
図5は本発明の第１実施例の再送制御説明図である。パケット1、パケット2、パケット3をそれぞれ送信アンテナATT₁〜ATT₃より送信したところ、パケット1、パケット2にエラーが発生してNACKとなり、パケット3は正しく受信されてACKとなったものとする。又、送信アンテナATT₁〜ATT₃の伝搬路状態を示す(SIR)は、SIR3＞SIR1＞SIR2である。アンテナ選択部ATS3は図4のフローに従って、伝搬路状態の良い順に送信アンテナをランキング付けすると、
ATT3→ATT1→ATT2
となり、NACKとなったデータストリームを、その送信アンテナの伝搬路状態が悪い順に並べると
パケット２→パケット１
となる。従って、パケット2を送信アンテナATT3で送信するものと決定し、パケット１を送信アンテナATT1で送信するものと決定するそして、ACK/NACK情報とアンテナ情報を、制御チャネルを介して送信局に送る。この結果、送信局は図5の右側に示すようにパケット1を送信アンテナATT1で再送し、パケット2を送信アンテナATT3で再送する。
以上のような方法を用いることにより、(1)NACKのデータストリームが複数ある場合や、(2)全てのデータストリームがNACKの場合、(3)（ACKアンテナ数）＜（NACKアンテナ数）のような場合に、本発明を適用して再送効率を高めることができる。なお、パケット合成における伝搬路状態を平均化し、再送の効率を高める効果は、NACKの送信アンテナを再送毎にランダムに割当てる方法によってもある程度、得ることができる。
以上第1実施例によれば、前回伝搬路条件の悪いアンテナから送信されたデータの誤り率を改善し、再送効率を向上することができる。また、MIMOシステムにおいて再送制御を行う場合、少ない再送回数で伝送を成功させ、再送効率を向上することができる。 (A) First Embodiment FIG. 1 is a block diagram of a multi-input multi-output transmission system of the first embodiment, FIG. 2 is a block diagram of a transmitter in the multi-input multi-output transmission system, and FIG. 3 is a multi-input multi-output transmission system. FIG. 2 is a configuration diagram of the receiving unit in FIG.
Outline of the first embodiment In the first embodiment, the receiving station RV detects ACK / NACK for each data stream, and at the same time, uses the pilot symbols orthogonally multiplexed for each transmission antenna, and the propagation path state for each antenna. Is estimated. Normally, a data stream that becomes ACK is transmitted from an antenna with a good propagation path state, and a data stream that becomes NACK is transmitted from an antenna with a poor propagation path state. Therefore, when retransmitting the data stream that becomes NACK, the data stream is compared with the propagation path of the transmission antenna that becomes ACK, and is selected to be retransmitted using the antenna with the better propagation path state. Note that the propagation path of the antenna that becomes ACK is generally better than the propagation path of the antenna that becomes NACK, so it is selected to retransmit using the transmission antenna that becomes ACK without comparing the propagation paths. May be.
In-operation receiving station RV in the first embodiment, it performs the MIMO channel separation process as well as estimate the channel h ₁₁ to h _MN using the data processing apparatus DPU pilot symbols. The data processor DTU demodulates the pilot symbols in channel estimation, and compares the phase and amplitude of the demodulated pilot symbols with the phase and amplitude of the known pilot symbols, thereby comparing the characteristics A · exp (jφ of the channels h ₁₁ to h _MN ). Since the pilot symbols transmitted from the respective transmitting antennas are orthogonal, the data processing device DPU can estimate the channels h _{11 to} h _MN .
The data processing device DPU uses the above-described methods such as ZF, MMSE, BLAST, and MLD for MIMO channel separation. The error detection unit EDT uses the CRC check and other methods to separate each data stream

ACK / NACK generator ANG sends the error detection result (ACK / NACK) for each data stream to the reverse radio link (transmitter TX, transmit antenna ATT, receive antenna ATR, receiver RX). To notify the transmitting station.
The propagation path estimation unit TPE estimates channel conditions (reception power S or SIR) for each transmission antenna using the channel estimation results h _{11 to} h _MN . For example, the propagation path estimation unit TPE calculates the received power Si of the transmission antenna ATTi (i = 1 to M) as

Estimated by The antenna selection unit ATS determines a transmission antenna to be used for retransmission based on the propagation path information and ACK / NACK information. As a transmission antenna used for retransmission, an antenna having a large power Si, that is, a good propagation path state is selected. Information on the transmission antenna (antenna number) used for retransmission is notified to the transmitting station along with the ACK / NACK information through the control channel in the reverse link (receiving station → transmitting station). The transmission antenna information (antenna number) used for retransmission is also notified to the data processing unit DPU and used for separation of the retransmission data stream.
Retransmission controller RTC of the transmitting station TR is input from the retransmission buffer RTB ₁ ~RTB _M based on the notified ACK / NACK information from the receiving station RV, it reads the data stream corresponding to NACK antenna assignment unit AAL To do. The antenna allocation unit AAL inputs the input retransmission data stream to the transmission antenna indicated by the antenna number notified from the receiving station. As described above, retransmission is performed from a transmission antenna having a good propagation state.
FIG. 4 shows a transmission antenna determination process flow for retransmission by the antenna selection unit ATS, which can be adopted in any of the following embodiments.
First, the transmission antennas are ranked in order of good propagation path conditions (step 101). Next, the NACK data streams are arranged in the order of poor propagation path conditions of the transmission antennas (step 102). Thereafter, i = 1 is set (step 103), and the i-th data stream is assigned to the i-th rank transmitting antenna (step 104). As a result, if i = 1, the data stream transmitted from the transmission antenna having the worst propagation path state and NACKed can be assigned to the transmission antenna having the best propagation path state and retransmitted.
Next, it is checked whether all retransmission data streams have been allocated (step 105). If not completed, i is incremented (step 106), and the processing from step 104 onward is repeated.
FIG. 5 is an explanatory diagram of retransmission control according to the first embodiment of this invention. Packet 1, Packet 2, where the packets 3 and transmitted from the transmitting antennas ATT ₁ ～ATT ₃ respectively, packet 1, NACK become an error occurs in the packet 2, packet 3 is received correctly and that a ACK . Further, (SIR) indicating the propagation path states of the transmitting antennas ATT _{1 to} ATT ₃ is SIR3>SIR1> SIR2. When the antenna selection unit ATS3 ranks transmission antennas in order of good propagation path state according to the flow of FIG.
ATT3 → ATT1 → ATT2
If the NACK data stream is arranged in the order of the poor propagation path state of the transmitting antenna, packet 2 → packet 1
It becomes. Therefore, it is determined that the packet 2 is transmitted by the transmission antenna ATT3, the packet 1 is determined by the transmission antenna ATT1, and ACK / NACK information and antenna information are transmitted to the transmitting station via the control channel. As a result, the transmitting station retransmits the packet 1 by the transmission antenna ATT1 and retransmits the packet 2 by the transmission antenna ATT3 as shown on the right side of FIG.
By using the above method, (1) when there are multiple NACK data streams, or (2) when all data streams are NACK, (3) (number of ACK antennas) <(number of NACK antennas) In such a case, the retransmission efficiency can be improved by applying the present invention. Note that the effect of averaging the propagation path states in packet combining and improving the efficiency of retransmission can be obtained to some extent by a method of randomly assigning NACK transmission antennas for each retransmission.
As described above, according to the first embodiment, it is possible to improve the error rate of data transmitted from an antenna having a poor propagation path condition last time and to improve retransmission efficiency. Also, when performing retransmission control in a MIMO system, transmission can be successfully performed with a small number of retransmissions, and retransmission efficiency can be improved.

毎に誤り検出を行い、ACK/NACK発生部ANGはデータストリーム毎にエラー検出結果（ACK/NACK）を逆方向の無線リンク(送信部TX,送信アンテナATT、受信アンテナATR、受信部RX)を用いて、制御チャネルにより送信局に通知する。伝搬路推定部TPEは、チャネル推定結果h₁₁〜h_MNを用いて、送信アンテナ毎の伝搬路状態（受信電力SあるいはSIR）を推定し、ACK/NACK情報と共に、逆方向の無線リンクを用いて、制御チャネルにより送信局に通知する。
送信局TRの再送制御部RTCは、受信局RVから通知されたACK/NACK情報に基づいて再送バッファRTB₁〜RTB_Mの中から、NACKに該当するデータストリームを読み出してアンテナ選択部ATSLに入力する。アンテナ選択部ATSLは、伝搬路情報およびACK/NACK情報に基づいて、再送に用いる送信アンテナを決定する。再送に用いる送信アンテナとしては、電力SiあるいはSIRが大きい、すなわち伝搬路状態が良好なアンテナを選択し、該アンテナの情報(アンテナ番号)をアンテナ選択情報多重部AIMに通知する。しかる後、アンテナ選択部ATSLは、再送バッファから入力された再送用のデータストリームを、送信部を介して前記決定した送信アンテナに入力する。以上により、再送は伝搬状態が良好な送信アンテナより行われる。又、アンテナ選択情報多重部AIMは再送用の送信アンテナのアンテナ番号を送信部TX₁に入力して単独であるいは再送データストリームに多重して送信アンテナATT₁より送信する。
受信局の各受信部RX₁〜RX_Nは受信信号をデータ処理部DPUに入力する。また、受信部RX₁は受信信号をアンテナ選択情報検出部AIDTに入力する。アンテナ選択情報検出部AIDTは入力信号より再送の送信アンテナを識別してデータ処理部DPUに入力する。データ処理部DPUはこの情報を用いて再送のデータストリームを分離して出力する。以上により、再送は伝搬状態が良好な送信アンテナより行われる。この結果、第2実施例によれば、前回伝搬路条件の悪いアンテナから送信されたデータの誤り率を改善し、再送効率を向上することができる。また、MIMOシステムにおいて再送制御を行う場合、少ない再送回数で伝送を成功させ、再送効率を向上することができる。
なお、アンテナ選択部ATSLは図4の処理フローに従って再送用のアンテナを決定することができる。このようにすることにより、パケット合成における伝搬路状態を平均化し、再送の効率を向上することができる。 (B) Second Embodiment FIG. 6 is a block diagram of a multi-input / multi-output transmission system according to a second embodiment. The same reference numerals are given to the same parts as those in the first embodiment.
Outline of the second embodiment In the first embodiment, the transmitting antenna for retransmitting the NACK data stream is determined by the antenna selection unit ATS of the receiving station and notified to the transmitting station. In the second embodiment, the propagation path state is determined. The transmission station transmits to the transmission station, and the transmission station antenna selection unit ATSL determines a transmission antenna to be retransmitted based on the propagation path state.
That is, in the first embodiment, the receiving station determines the antenna to be used for retransmission, but in the second embodiment, the transmitting station determines the antenna. The receiving station notifies the transmission station TR of the propagation path information (S, SIR) estimated by the propagation path estimation unit TPE using the reverse link control channel. The antenna selection unit ATSL of the transmitting station performs processing for selecting and assigning antennas to be used for retransmission based on propagation path information and ACK / NACK information. The information on the transmitting antenna determined by the transmitting station is notified to the receiving station RV by the antenna information multiplexing unit AIM through the control channel using one or a plurality of transmitters. In the receiving station, the antenna selection information notified by the control channel is detected by the antenna information detection unit AIDT and notified to the data processing device DPU.
Operation of the second embodiment In the receiving station RV, the data processing device DPU estimates the channels h ₁₁ to h _MN using pilot symbols as in the first embodiment and performs MIMO channel separation processing (data stream separation processing). Do. The error detection unit EDT uses the CRC check and other methods to separate each data stream

ACK / NACK generator ANG sends the error detection result (ACK / NACK) for each data stream to the reverse radio link (transmitter TX, transmit antenna ATT, receive antenna ATR, receiver RX). And notifies the transmitting station via the control channel. The channel estimation unit TPE estimates channel conditions (received power S or SIR) for each transmission antenna using the channel estimation results h _{11 to} h _MN, and uses a radio link in the reverse direction along with ACK / NACK information. To the transmitting station through the control channel.
Retransmission controller RTC of the transmitting station TR is input from the retransmission buffer RTB ₁ ~RTB _M based on the notified ACK / NACK information from the receiving station RV, it reads the data stream corresponding to NACK the antenna selector ATSL To do. The antenna selection unit ATSL determines a transmission antenna used for retransmission based on the propagation path information and ACK / NACK information. As a transmission antenna used for retransmission, an antenna having high power Si or SIR, that is, a good propagation path state is selected, and the antenna information (antenna number) is notified to the antenna selection information multiplexing unit AIM. Thereafter, the antenna selection unit ATSL inputs the retransmission data stream input from the retransmission buffer to the determined transmission antenna via the transmission unit. As described above, retransmission is performed from a transmission antenna having a good propagation state. Also, the antenna selection information multiplexing unit AIM inputs the antenna number of the transmission antenna for retransmission to the transmission unit TX ₁ and transmits it alone or multiplexed on the retransmission data stream from the transmission antenna ATT ₁ .
Each of the receiving units RX _{1 to} RX _N of the receiving station inputs a received signal to the data processing unit DPU. The receiving unit RX ₁ inputs the received signal to the antenna selection information detecting unit AIDT. The antenna selection information detection unit AIDT identifies the retransmission transmission antenna from the input signal and inputs it to the data processing unit DPU. The data processing unit DPU uses this information to separate and output the retransmission data stream. As described above, retransmission is performed from a transmission antenna having a good propagation state. As a result, according to the second embodiment, it is possible to improve the error rate of data transmitted from an antenna having a poor propagation path condition last time, and improve retransmission efficiency. Also, when performing retransmission control in a MIMO system, transmission can be successfully performed with a small number of retransmissions, and retransmission efficiency can be improved.
The antenna selection unit ATSL can determine the antenna for retransmission according to the processing flow of FIG. By doing so, it is possible to average the propagation path state in the packet synthesis and improve the efficiency of retransmission.

は合成部ADDを通過して誤り検出部EDTと書き込み制御部WCTに入力する。誤り検出部EDTにおける誤り検出処理の結果、誤りが検出されなければ書き込み制御部WCTは再送合成バッファRTBFに何も格納しない。又、図示しないACCK/NACK発生部ANGはACKを送信局に送る。一方、誤り検出処理の結果、誤りが検出されると、書込み制御部WCTは誤りを含むパケットをパケット番号を付して再送合成バッファRTBFに格納する。又、ACK/NACK発生部ANGはNACKを送信局に送る。この結果、送信局からNACKのパケットが再送されてくると、該パケットの番号に応じたパケットを再送合成バッファRTBFから読み出して合成部ADDに入力する。合成部ADDは再送パケットとバッファから読み出されたパケットとを合成して出力する。データ合成により、受信品質が改善され、再送回数が増えるほど、改善の度合いが高くなり、パケット受信の成功率が高まる。
第3実施例において、送信局のアンテナ選択部ATSLは図4の処理フローに従って送信アンテナを決定して再送する。このようにすると以下の利点がある。すなわち、伝搬路状態の最も悪いアンテナから送信されたデータストリームが、伝搬路状態の最も良いアンテナから再送されるように、逆順のランキングを用いてアンテナ割当てを行うため、パケット合成の効果を全てのデータストリームに対して平均して得ることができ、NACKとなるデータストリームの発生確率を低減することができる。
第3実施例では、送信局において使用するアンテナが再送の度に異なるが、受信局のデータ処理装置DPUにおいて、再送に使用されたアンテナを判別するため、正しい再送パケット同士を合成することができる。なお、再送合成部を第1実施例のデータ復調／復号部の後に設けて第3実施例とすることができる。 (C) Third Embodiment FIG. 7 is a block diagram of a receiving station according to the third embodiment, which is different from the second embodiment only in that a retransmission combining unit RTC is provided. Although not shown, the transmitting station has the same configuration as that of the second embodiment.
The reproduction synthesis unit RTC synthesizes the retransmission packet and the previously transmitted NACK packet in order to improve the reception quality of the retransmission signal. That is, the reproduction synthesis unit RTC accumulates, in the retransmission synthesis buffer, a packet including an error that has failed to be received and has issued a retransmission request (NACK information). When the retransmitted packet (data stream) is received, the retransmitted packet and the packet (data stream) in the buffer are combined. By this data synthesis, the reception quality (SIR of the received data signal) is improved. As the number of retransmissions increases, the degree of improvement increases and the success rate of packet reception increases.
FIG. 8 is a block diagram of the reproduction synthesis unit RTC, and nothing is initially stored in the retransmission synthesis buffer RTBF. For this reason, the data stream (packet)

Passes through the synthesis unit ADD and inputs to the error detection unit EDT and the write control unit WCT. If no error is detected as a result of the error detection processing in the error detection unit EDT, the write control unit WCT stores nothing in the retransmission synthesis buffer RTBF. An ACCK / NACK generator ANG (not shown) sends ACK to the transmitting station. On the other hand, if an error is detected as a result of the error detection process, the write control unit WCT attaches a packet containing the error to the retransmission synthesis buffer RTBF with a packet number. The ACK / NACK generation unit ANG sends NACK to the transmitting station. As a result, when a NACK packet is retransmitted from the transmitting station, a packet corresponding to the packet number is read from the retransmission combining buffer RTBF and input to the combining unit ADD. The combining unit ADD combines the retransmission packet and the packet read from the buffer and outputs the combined packet. As data reception improves reception quality and the number of retransmissions increases, the degree of improvement increases and the success rate of packet reception increases.
In the third embodiment, the antenna selection unit ATSL of the transmission station determines the transmission antenna according to the processing flow of FIG. 4 and retransmits it. This has the following advantages. In other words, the antenna allocation is performed using the reverse ranking so that the data stream transmitted from the antenna with the worst channel condition is retransmitted from the antenna with the best channel condition. It can be obtained on the average for the data stream, and the occurrence probability of the data stream that becomes NACK can be reduced.
In the third embodiment, the antenna used in the transmitting station is different every time it is retransmitted. However, in the data processing device DPU of the receiving station, the correct retransmission packet can be synthesized to determine the antenna used for the retransmission. . Note that the retransmission combining unit can be provided after the data demodulating / decoding unit of the first embodiment to form the third embodiment.

(D) Fourth Embodiment FIG. 9 is a block diagram of the fourth embodiment, and the same components as those of the second embodiment are denoted by the same reference numerals. The difference is that (1) instead of the propagation path state estimation unit TPE, there is an error count unit ERC that counts the number of errors for each data stream and sends it to the transmission station, and (2) the antenna selection unit ATSL of the transmission station The point is that a transmission antenna for retransmission is determined based on the number of errors instead of the power S or SIR.
The error detection unit EDT performs error detection using CRC (Cyclic Redundancy Check), and can determine the number of errors that occur in each data stream. Therefore, this error number information is sent to the antenna selection unit ATSL of the transmitting station, and the antenna selection unit ATSL transmits the data stream in which the most error has occurred based on the number of errors to the antenna with the best channel condition (the number of errors is the highest). Assign to retransmit using fewer antennas. In this way, propagation paths in packet combining can be averaged, and the efficiency of retransmission control can be increased. In the first embodiment, an error count unit ERC may be provided instead of the propagation path state estimation unit TPE, and a retransmission transmission antenna may be determined based on the number of errors.

ここで、s₁はアンテナATT₁からの送信データ信号、s₂はアンテナATT₂からの送信データ信号、x₁は受信アンテナATR₁の受信信号である。送信データ信号s₁がNACK、送信データ信号s₂がACKとなった場合は、右側に示めすように送信データ信号s₁をアンテナ１とアンテナ２の両方から再送する。この場合、受信アンテナのATR₁の受信信号x₁は

となる。２つの送信アンテナATT₁，ATT₂からの伝搬路は独立なので、２つの信号は空間でランダムに合成され、単純に送信電力が２倍となったことに相当する。これにより、誤り率を改善できる。 (E) Other means for improving the efficiency of retransmission control
As another means for improving the efficiency of retransmission control in a MIMO system, a method of retransmitting a NACK data stream using a plurality of antennas can be considered. The simplest method is a method of transmitting the same signal from a plurality of antennas, and the following method can be applied to any of the first to fourth embodiments.
Retransmit the same signal using multiple antennas As shown in FIG. 10, when the number of transmitting antennas is 2 and the number of receiving antennas is 2, a new data stream in _one receiving antenna ATR ₁ is represented as follows: Is done. (However, in the following discussion, the influence of noise is omitted.)

Here, s ₁ is a transmission data signal from the antenna ATT ₁ , s ₂ is a transmission data signal from the antenna ATT ₂ , and x ₁ is a reception signal of the reception antenna ATR ₁ . When the transmission data signal s ₁ is NACK and the transmission data signal s ₂ is ACK, the transmission data signal s ₁ is retransmitted from both the antenna 1 and the antenna 2 as shown on the right side. In this case, the received signal x ₁ of ATR ₁ of the receiving antenna is

It becomes. Since the propagation paths from the _two transmission antennas ATT ₁ and ATT ₂ are independent, the two signals are randomly synthesized in space, which corresponds to simply double the transmission power. Thereby, the error rate can be improved.

となる。ここで、s₁(0),s₁(1)は、時間的に連続した送信データシンボルを、x₁(0),x₁(1)は、時間的に連続した受信データシンボルを表す。この時、受信局でチャネル推定部12およびSTTDデコーダ13は次式

で示すデコード処理を行う。この結果、送信ダイバーシチゲインが得られ、誤り率を改善できる。なお、STTDコーダを第1〜第4実施例の送信局の適所に、例えばアンテナ選択部ATSL内に設け、また、STTDデコーダを受信局の適所に、例えばデータ処理装置DPU内に設けることによりSTTDを用いた再送を実現できる。 ・ Retransmission using STTD
By using STTD (Space Time Transmit Diversity), transmission diversity gain can be obtained at the time of retransmission. FIG. 11 is an explanatory diagram of a retransmission principle using STTD. In the STTD method, transmission data signals s ₁ (0) and s ₁ (1) that have become NACKs are encoded by the STTD encoder 11, and two sets of data selected by the encoding are transmitted to the two antennas ATT ₁ and ATT ₂ . Enter and send. In other words, when STTD encoder 11 inputs a signal that is continuous in time to s ₁ (0), s ₁ (1), s ₁ (0), −s ₁ * (1) and s ₁ (1), s ₁ * Two sets of continuous signals (0) are output. As a result, the received signals x ₁ (0), x ₁ (1) of the receiving antenna ATR1 are

It becomes. Here, s ₁ (0) and s ₁ (1) represent temporally continuous transmission data symbols, and x ₁ (0) and x ₁ (1) represent temporally continuous received data symbols. At this time, the channel estimation unit 12 and STTD decoder 13 at the receiving station

The decoding process indicated by As a result, transmission diversity gain can be obtained and the error rate can be improved. It is to be noted that an STTD coder is provided at an appropriate location of the transmitting station of the first to fourth embodiments, for example, in the antenna selection unit ATSL, and an STTD decoder is provided at an appropriate location of the receiving station, for example, in the data processing device DPU. Retransmission using can be realized.

-Retransmission by changing the modulation method and coding rate By changing the modulation method and coding rate, retransmission can be performed using a plurality of transmission antennas. FIG. 12 is a diagram for explaining the principle when the modulation method is changed. For example, if one of the two data streams transmitted from the two transmission antennas ATT ₁ and ATT ₂ at 16QAM (4 bits) becomes NACK and the other becomes ACK, the modulation is performed when resending the NACK data stream. Change the method to QPSK (2 bits). By changing the modulation method to QPSK (2 bits), the number of symbols in the data stream is doubled, so that the data is distributed to the _two transmission antennas ATT ₁ and ATT ₂ for transmission. As a result, it is possible to perform retransmission using the QPSK modulation method that is less affected by noise while maintaining the MIMO transmission method.
As shown in FIG. 13, when a data stream that has been modulated with 64QAM and encoded with error correction at a coding rate R = 2/3 is NACK, the modulation method is 16QAM and the coding rate is Change to R = 1/2. In this way, since the number of symbols in the data stream is doubled, if the transmission is distributed to the _two transmission antennas ATT ₁ and ATT ₂ , the modulation method is small in the influence of noise without changing the MIMO transmission method. In addition, retransmission using a coding rate having a high error correction capability can be performed. Such a method is effective when MIMO channel separation is functioning well, but errors remain due to limitations of the modulation scheme and coding rate.
As described above, according to the present invention, it is possible to improve the data error rate and improve the retransmission efficiency. Also, when performing retransmission control in a MIMO system, transmission can be successfully performed with a small number of retransmissions, and retransmission efficiency can be improved.

・ Additional notes
(Supplementary note 1) A transmission station that transmits each of a plurality of data streams from separate transmission antennas, and a reception station that separates and outputs the data streams multiplexed in space from signals received by the plurality of reception antennas In a multi-input multi-output transmission system,
The receiving station is
Means for detecting the presence or absence of errors in each data stream;
Means for estimating the propagation path state of each transmitting antenna;
Means for notifying the transmission side of retransmission necessity information for each data stream created based on the presence or absence of an error and the propagation path state of each transmission antenna;
The transmitting station comprises:
Means for determining a transmission antenna for transmitting a data stream requiring retransmission based on the notified propagation path state of each transmission antenna;
Means for retransmitting a data stream requiring retransmission from the determined transmission antenna;
A multi-input multi-output transmission system characterized by comprising:
(Appendix 2) The transmitting station further notifies the receiving station of identification information of a transmitting antenna that transmits the data stream requiring retransmission,
A data stream separating means for separating the retransmitted data stream based on the notified antenna identification information;
The multi-input multi-output transmission system according to appendix 1, characterized by comprising:
(Supplementary Note 3) A transmission station that transmits each of a plurality of data streams from separate transmission antennas and a reception station that separates and outputs the data streams multiplexed in space from signals received by the plurality of reception antennas In a multi-input multi-output transmission system,
The receiving station is
Means for detecting the presence or absence of errors in each data stream;
Means for estimating the propagation path state of each transmitting antenna;
Means for determining a transmission antenna for retransmission based on a propagation path state of the transmission antenna;
Means for notifying a transmitting station of retransmission necessity information for each of the data streams created based on the presence or absence of an error and the identification information of the determined retransmission transmitting antenna;
The transmitting station comprises:
Means for retransmitting the data stream that needs to be retransmitted from the notified retransmission transmitting antenna;
A multi-input multi-output transmission system characterized by comprising:
(Additional remark 4) The said transmission part multiplexes the pilot symbol which mutually orthogonalizes to each said data stream, and transmits from each transmission antenna,
The propagation path state estimation means estimates the propagation path state of each antenna using the channel estimation value of each channel estimated using the pilot symbol.
The multi-input multi-output transmission system according to appendix 1 or 3, characterized by the above.
(Appendix 5) The receiving station
A buffer memory to store the demodulated data stream,
Combining means for combining the retransmitted data stream and the data stream stored in the buffer memory;
The error presence detection means performs error detection processing on the synthesized data stream.
The multi-input multi-output transmission system according to appendix 1 or 3, wherein
(Supplementary Note 6) The transmitting antenna determining means of the receiving station or transmitting station performs ranking of transmitting antennas in the order of good propagation path state, and retransmits the substreams requiring retransmission from the transmitting antenna with the worst propagation path condition last time. Reassign transmission antennas in the reverse order of ranking so that the transmitted data stream requiring retransmission is transmitted from the transmission antenna with the best propagation path state.
The multi-input multi-output transmission system according to appendix 1 or 3, characterized by the above.
(Supplementary note 7) The error detection means counts the number of error occurrences in a data stream that needs to be retransmitted, and the transmission antenna determination means of the receiving station or the transmission station sends a retransmission request that is transmitted from an antenna having the highest number of error occurrences. A transmission antenna for reproduction is determined so that the data stream is transmitted from the antenna having the best propagation path state.
The multi-input multi-output transmission system according to appendix 1 or 3, characterized by the above.
(Supplementary note 8) When all data streams or a plurality of data streams need to be retransmitted, the transmission antenna determining means of the receiving station or transmitting station randomly assigns an antenna for retransmitting each data stream.
The multi-input multi-output transmission system according to appendix 1 or 3, characterized by the above.
(Supplementary Note 9) The transmission antenna determining means of the receiving station or the transmitting station performs antenna allocation so that the data stream that needs to be retransmitted is retransmitted from the antenna that has transmitted the data stream that is no longer necessary for retransmission.
The multi-input multi-output transmission system according to appendix 1 or 3, characterized by the above.
(Supplementary Note 10) The transmission antenna determining means of the receiving station or transmitting station retransmits one data stream requiring retransmission using a plurality of antennas, also using the antenna that transmitted the data stream that is no longer required to be retransmitted. To assign antennas,
The multi-input multi-output transmission system according to appendix 1 or 3, characterized by the above.
(Additional remark 11) The data stream retransmission means of the transmission station has a transmission diversity configuration, and retransmits one data stream using a plurality of antennas, using the transmission diversity.
The multi-input multi-output transmission system according to appendix 10, wherein
(Supplementary Note 12) The data stream retransmission means of the transmitting station includes means for changing the modulation degree or coding rate, and when retransmitting one data stream using a plurality of antennas, the modulation degree of the data stream to be retransmitted is determined. Dividing into a plurality of sub-data streams by lowering or reducing the coding rate, and transmitting each sub-data stream using a plurality of antennas,
The multi-input multi-output transmission system according to appendix 10, wherein
(Supplementary Note 13) Reception of a multiple-input multiple-output transmission system that transmits each of a plurality of data streams from separate transmission antennas and separates and outputs the data streams multiplexed in space from signals received by the plurality of reception antennas In the station
A plurality of receiving antennas for receiving signals transmitted from the plurality of transmitting antennas;
Means for separating and demodulating a data stream multiplexed in space from signals received by the plurality of receiving antennas;
Means for detecting the presence or absence of an error in each demodulated data stream;
Means for estimating the propagation path state of each transmitting antenna;
Means for notifying the transmission side of retransmission necessity information for each data stream created based on the presence or absence of an error and the propagation path state of each transmission antenna;
The data stream separating / demodulating means separates and demodulates the retransmitted data stream,
A receiving station characterized by that.
(Supplementary Note 14) The data stream separation / demodulation means separates and demodulates the retransmitted data stream based on identification information of a retransmission transmission antenna sent from a transmission station.
The receiving station according to appendix 13, characterized in that.
(Supplementary Note 15) Reception of a multiple-input multiple-output transmission system that transmits each of a plurality of data streams from separate transmission antennas and separates and outputs the data streams multiplexed in space from signals received by the plurality of reception antennas In the station
A plurality of receiving antennas for receiving signals transmitted from the plurality of transmitting antennas;
Means for separating and demodulating a data stream multiplexed in space from signals received by the plurality of receiving antennas;
Means for detecting the presence or absence of an error in each demodulated data stream;
Means for estimating the propagation path state of each transmitting antenna;
Means for determining a transmission antenna for retransmission based on a propagation path state of the transmission antenna;
Means for notifying a transmitting station of retransmission necessity information for each of the data streams created based on the presence or absence of an error and the identification information of the determined retransmission transmitting antenna;
The data stream separating / demodulating means separates and demodulates the retransmitted data stream,
A receiving station characterized by that.
(Appendix 16) The receiving station
A buffer memory to store the demodulated data stream,
Combining means for combining the retransmitted data stream and the data stream stored in the buffer memory;
The error presence detection means performs error detection processing on the synthesized data stream.
The receiving station according to appendix 13 or 15, characterized in that.
(Supplementary note 17) Transmission of a multiple-input multiple-output transmission system that transmits each of a plurality of data streams from separate transmission antennas and separates and outputs the data streams multiplexed in space from signals received by the plurality of reception antennas In the station
Means for transmitting each of a plurality of data streams from separate transmit antennas;
A receiving unit that receives from the receiving station the retransmission necessity information for each data stream and the propagation path state of each transmitting antenna,
Means for determining a transmission antenna for transmitting a data stream requiring retransmission based on the notified propagation path state of each transmission antenna;
Means for retransmitting a data stream requiring retransmission from the determined transmission antenna;
A transmitting station comprising:
(Supplementary Note 18) The transmitting station further notifies the receiving station of identification information of a transmitting antenna that transmits the data stream requiring retransmission,
18. The transmitting station according to appendix 17, characterized by comprising:
(Supplementary note 19) Transmission of a multiple-input multiple-output transmission system that transmits each of a plurality of data streams from separate transmission antennas and separates and outputs the data streams multiplexed in space from signals received by the plurality of reception antennas In the station
Means for transmitting each of a plurality of data streams from separate transmit antennas;
Receiving unit for receiving from the receiving station the retransmission necessity information for each data stream and the identification information of the transmitting antenna for retransmission,
Means for retransmitting the data stream that needs to be retransmitted from the notified retransmission transmitting antenna;
A transmitting station comprising:
(Supplementary Note 20) The transmitting station multiplexes and transmits pilot symbols orthogonal to each other from each transmitting antenna to the data stream,
The transmitting station according to appendix 17 or 19, characterized by comprising:

1 is a configuration diagram of a multiple-input multiple-output transmission system according to a first embodiment. FIG. It is a block diagram of the transmission part in a multiple input multiple output transmission system. It is a block diagram of the receiving part in a multiple input multiple output transmission system. It is a transmission antenna determination processing flow for retransmission by the antenna selection unit. FIG. 6 is an explanatory diagram of retransmission control according to the first embodiment of this invention. FIG. 6 is a configuration diagram of a multiple-input multiple-output transmission system according to a second embodiment. FIG. 10 is a configuration diagram of a receiving station according to a third embodiment. It is a block diagram of a reproduction | regeneration synthetic | combination part. It is a block diagram of the receiving station of 4th Example. It is explanatory drawing (the same signal is retransmitted using a several antenna) of the means which improves the efficiency of the retransmission control in a MIMO system. It is explanatory drawing (retransmission using STTD) of the means which improves the efficiency of the retransmission control in a MIMO system. It is explanatory drawing (resending by changing a modulation system) of the means which improves the efficiency of the retransmission control in a MIMO system. FIG. 10 is an explanatory diagram of means for improving the efficiency of retransmission control in a MIMO system (retransmission by changing the modulation scheme and coding rate). It is a block diagram of a MIMO system. It is a block diagram of the receiver in the conventional digital radio | wireless communications system. It is a block diagram of the transmitter in the conventional digital radio | wireless communications system. It is explanatory drawing of the prior art example when resending control is applied in a MIMO system.

Explanation of symbols

RV receiving station
ATRI (i = 1 to N) Reception antenna DPU Data processing unit EDT Error detection unit TPE Channel estimation unit TR Transmitting station RTC Retransmission control unit
RTB _{1 to} RTB _M retransmission buffer AAL Antenna allocation unit
ATTi (i = 1 to M) Transmitting antenna

Claims (3)

In a communication method in a mobile communication system capable of simultaneously transmitting a plurality of data streams using a MIMO scheme from a transmitting station having a plurality of antennas to a receiving station having a plurality of antennas,
Of the first data stream and the second data stream transmitted simultaneously from the first antenna and the second antenna of the transmitting station, the first data stream is normally received at the receiving station, When the second data stream cannot be normally received at the receiving station, retransmission of the second data stream is performed using the first antenna and the second antenna .
A communication method characterized by the above. In a mobile communication system capable of simultaneously transmitting a plurality of data streams using a MIMO scheme from a transmitting station having a plurality of antennas to a receiving station having a plurality of antennas,
The transmitting station includes an assigning unit that assigns data so as to transmit the first data stream and the second data stream from each of the first antenna and the second antenna,
The receiving station can normally receive the first data stream of the first data stream and the second data stream at the receiving station, and receive the second data stream at the receiving station normally. A transmission unit that transmits the reception result of the first data stream and the second data stream to the transmission station when there is not,
The allocating unit performs allocation so as to transmit using the first antenna and the second antenna when performing retransmission of the second data stream according to the reception result.
A mobile communication system. In a transmitting station of a mobile communication system capable of simultaneously transmitting a plurality of data streams using a MIMO scheme from a transmitting station having a plurality of antennas to a receiving station having a plurality of antennas,
A first antenna transmitting a data stream, a second antenna,
An assigning unit for assigning data so as to transmit a first data stream and a second data stream from each of the first antenna and the second antenna;
Of the first data stream and the second data stream, the first data stream is normally received by the receiving station, and the second data stream cannot be normally received by the receiving station A receiving unit for receiving the result from the receiving station;
The allocating unit performs allocation so as to transmit using the first antenna and the second antenna when performing retransmission of the second data stream according to the reception result.
A transmitting station of a mobile communication system.

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