WO2007114374A1 - Mimo受信装置およびmimo通信システム - Google Patents
Mimo受信装置およびmimo通信システム Download PDFInfo
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- WO2007114374A1 WO2007114374A1 PCT/JP2007/057216 JP2007057216W WO2007114374A1 WO 2007114374 A1 WO2007114374 A1 WO 2007114374A1 JP 2007057216 W JP2007057216 W JP 2007057216W WO 2007114374 A1 WO2007114374 A1 WO 2007114374A1
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B7/00—Radio transmission systems, i.e. using radiation field
- H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
- H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B7/00—Radio transmission systems, i.e. using radiation field
- H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
- H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
- H04B7/06—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station
- H04B7/0697—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using spatial multiplexing
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B7/00—Radio transmission systems, i.e. using radiation field
- H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
- H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
- H04B7/08—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the receiving station
- H04B7/0837—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the receiving station using pre-detection combining
- H04B7/0842—Weighted combining
- H04B7/0848—Joint weighting
- H04B7/0854—Joint weighting using error minimizing algorithms, e.g. minimum mean squared error [MMSE], "cross-correlation" or matrix inversion
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L1/00—Arrangements for detecting or preventing errors in the information received
- H04L1/02—Arrangements for detecting or preventing errors in the information received by diversity reception
- H04L1/06—Arrangements for detecting or preventing errors in the information received by diversity reception using space diversity
- H04L1/0618—Space-time coding
- H04L1/0625—Transmitter arrangements
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L1/00—Arrangements for detecting or preventing errors in the information received
- H04L1/02—Arrangements for detecting or preventing errors in the information received by diversity reception
- H04L1/06—Arrangements for detecting or preventing errors in the information received by diversity reception using space diversity
- H04L1/0618—Space-time coding
- H04L1/0631—Receiver arrangements
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L1/00—Arrangements for detecting or preventing errors in the information received
- H04L1/02—Arrangements for detecting or preventing errors in the information received by diversity reception
- H04L1/06—Arrangements for detecting or preventing errors in the information received by diversity reception using space diversity
- H04L1/0618—Space-time coding
- H04L1/0637—Properties of the code
- H04L1/0643—Properties of the code block codes
Definitions
- the present invention relates to a MIMO receiver and a MIMO communication system.
- MIMO technology is disclosed in, for example, Non-Patent Document 1 and includes a plurality of antenna elements in both a transmitter and a receiver, and transmission of received signals with low correlation between antennas. Spatial multiplexing transmission can be realized in a portable environment. In this case, different data sequences are transmitted from a plurality of antennas provided in the transmitter using physical channels having the same time, the same frequency, and the same code for each antenna, and the receiver uses the plurality of antennas provided in the receiver. Different data series are separately received based on the received signal.
- Non-Patent Document 2 for the separate reception method, and transmission sequences from a plurality of wireless terminal devices are ZF (Zero Forcing), MMSE (Minumum Mean) It is possible to use techniques such as 3 ⁇ 4qure Error), MLD (Maximum Lilelihood Detection), and interference canceller. As a result, by using a plurality of spatial multiplexing channels, it is possible to achieve high-speed wireless communication without using multilevel modulation.
- Non-Patent Document 1 G.J.roschini, Layered space-time architecture for wireless communication in a fading environment when using multi-element antennas, Bell Labs Tech. J., pp.4 to 59, Autumn 1996
- Patent Document 2 John G. Proakis, Digital Communications Fourth Edition, "Chap. 14, McGrawHill, 2001.
- An object of the present invention has been made in view of the strong point, and a MIMO receiver and a MIMO communication capable of reducing the hardware scale even when the number of antennas used for MIMO communication is increased. Is to provide a system.
- the MIMO receiver of the present invention receives a spatially multiplexed signal in which different transmission signals are spatially multiplexed, and performs a linear operation on the received spatially multiplexed signal to separate the spatially multiplexed signal.
- a configuration is adopted that includes first signal separation means and second signal separation means for separating the separated spatially multiplexed signal into transmission signals.
- the MIMO communication system of the present invention includes a radio transmission apparatus comprising transmission signal configuration means for configuring different transmission signals, and transmission means for transmitting the transmission signals through different antennas, and the transmission Multiplexed N spatially multiplexed signals with spatially multiplexed signals Receiving means, first signal separating means for performing linear operation on the received spatially multiplexed signal and separating it into a group of spatially multiplexed signals having the number of transmission signals smaller than the number of multiplexed N, and each group
- a radio receiving device comprising: a second signal separation unit that separates the spatially multiplexed signal into each transmission signal included in the spatially multiplexed signal; and a signal processing unit that processes the separated transmission signal.
- MIMO communication system comprising transmission signal configuration means for configuring different transmission signals, and transmission means for transmitting the transmission signals through different antennas, and the transmission Multiplexed N spatially multiplexed signals with spatially multiplexed signals Receiving means, first signal separating means for performing linear operation on the received spatially multiplex
- the present invention it is possible to provide a MIMO receiver and a MIMO communication system capable of reducing the hardware scale even when the number of antennas used for MIMO communication is increased.
- FIG. 1 shows a configuration of a wireless communication system according to Embodiment 1 of the present invention.
- FIG. 2 is a diagram showing a detailed configuration of the wireless communication system in FIG.
- FIG. 3 is a block diagram showing the configuration of the wireless communication device (transmission side) in FIG.
- FIG. 4 is a block diagram showing the configuration of the wireless communication device (reception side) in FIG.
- FIG. 5 is a block diagram showing another configuration of the wireless communication device (receiving side)
- FIG. 6 is a diagram showing another configuration of the wireless communication system according to the first embodiment.
- FIG. 7 is a block diagram showing the configuration of the wireless communication device (receiving side) according to the second embodiment.
- FIG. 8 is a block diagram showing the configuration of the replica generation unit in FIG.
- FIG. 9 is a block diagram showing the configuration of the interference canceller in FIG.
- FIG. 10 is a diagram showing the configuration of the replica subtraction unit in FIG.
- FIG. 11 is a block diagram showing another configuration of the wireless communication apparatus (receiving side) according to the second embodiment.
- FIG. 12 is a block diagram showing the configuration of the replica generation unit in FIG.
- FIG. 13 is a block diagram showing the configuration of the interference canceller in FIG.
- FIG. 14 is a diagram showing the configuration of the replica subtraction unit in FIG.
- FIG. 15 is a block diagram showing another configuration of the wireless communication apparatus (receiving side) according to the second embodiment.
- FIG. 16 is a block diagram showing the configuration of the replica generation unit in FIG.
- FIG. 17 is a block diagram showing the configuration of the interference canceller in FIG.
- FIG. 18 is a diagram showing the configuration of the replica subtraction unit in FIG.
- FIG. 19 shows a configuration of a wireless communication system according to a third embodiment.
- FIG. 20 is a block diagram showing the configuration of the wireless communication device (transmission side) according to the fourth embodiment.
- FIG. 21 is a block diagram showing the configuration of the wireless communication device (receiving side) according to the fourth embodiment.
- FIG. 22 shows a configuration of a wireless communication system according to the fifth embodiment.
- FIG. 23 shows another configuration of the radio communication system according to the fifth embodiment.
- FIG. 24 shows another configuration of the radio communication system according to the fifth embodiment.
- FIG. 25 is a diagram showing another configuration of the wireless communication system according to the fifth embodiment.
- FIG. 26 is a block diagram showing the configuration of the wireless communication device (receiving side) according to the sixth embodiment.
- FIG. 27 is a block diagram showing another configuration of the wireless communication apparatus (receiving side) according to the sixth embodiment.
- FIG. 28 is a block diagram showing another configuration of the wireless communication apparatus (receiving side) according to the sixth embodiment.
- FIG. 29 is a block diagram showing the configuration of the wireless communication device (receiving side) according to the seventh embodiment.
- FIG. 30 shows a configuration of a wireless communication system according to an eighth embodiment.
- FIG. 31 shows a configuration of a wireless communication system according to the ninth embodiment.
- FIG. 32 shows another configuration of the wireless communication system according to the ninth embodiment.
- FIG. 33 shows another configuration of the wireless communication system according to the ninth embodiment.
- FIG. 34 is a block diagram showing another configuration of the encoding unit in the wireless communication apparatus (transmitting side) according to the fifth embodiment.
- FIG. 35 is a block diagram showing another configuration of the received signal processing unit in the wireless communication apparatus (receiving side) according to the fifth embodiment.
- FIG. 36 is a block diagram showing the configuration of the wireless communication apparatus (receiving side) according to the tenth embodiment
- a radio communication system 10 includes a radio communication device 100 and a radio communication device 200, and transmits and receives spatially multiplexed signals using, for example, the MIMO communication method. .
- both wireless communication device 100 and wireless communication device 200 In this example, there are two antennas, wireless communication device 100 transmits spatially multiplexed signals using four antennas, and wireless communication device 200 receives spatially multiplexed signals using four antennas. Yes. That is, radio communication apparatus 100 transmits a transmission signal from each antenna carrier, and this transmission signal is spatially multiplexed before reaching radio communication apparatus 200. Radio communication apparatus 200 receives spatially multiplexed signals that have been propagated through different propagation paths at each antenna.
- FIG. 2 is a diagram showing the main configuration of radio communication apparatus 100 and radio communication apparatus 200.
- the data generation unit 110 generates transmission data and outputs the transmission data to the transmission signal configuration unit 120.
- Transmission signal configuration section 120 is based on one system of transmission data generated by data generation section 110.
- N transmission signals corresponding to the number of antennas 140 are generated.
- Transmission section 130 performs predetermined radio transmission processing (DZA conversion, up-conversion, etc.) on each of the N transmission signals generated by transmission signal configuration section 120, and performs radio transmission processing. Transmit signals are transmitted via different antennas 140.
- predetermined radio transmission processing DZA conversion, up-conversion, etc.
- Receiving section 220 receives N multiplexed spatially multiplexed signals, which are spatially multiplexed with different transmission signals (transmission signals of radio terminal apparatus 100), via a plurality of propagation paths.
- Receiver 22 receives N multiplexed spatially multiplexed signals, which are spatially multiplexed with different transmission signals (transmission signals of radio terminal apparatus 100), via a plurality of propagation paths.
- 0 is a radio reception process (downconvert, AZD conversion, etc.) for each spatially multiplexed signal received by each of the antennas 210, and the spatially multiplexed signal after the radio reception process is converted into the first signal separation unit 230. Output to.
- the first signal separation unit 230 performs a first separation process, which is a rough and separated process, on the spatially multiplexed signal after the radio reception process by a predetermined linear operation.
- the second signal separation unit 240 performs a second separation process, which is a precise separation process, on the signal after the first separation process, and corresponds to the transmission signal transmitted from the radio communication device 100. Get N received signals.
- Reception signal processing section 250 performs reception signal processing on each of the reception signals from second signal separation section 240, and outputs reception data.
- a spatially multiplexed signal when separated, it is separated into received signals by a one-stage separation process.
- separation processing that has been performed in one stage in the past is divided into multiple stages that become more precise as the next stage progresses, so that even if the number of antennas of the radio communication device (100, 200) increases, that is, spatially multiplexed signals
- the amount of processing in one stage is reduced, and a conventional separation apparatus can be used in each stage, so that development costs can be reduced.
- the separation device becomes more complex and the hardware scale increases as the number of multiplexed spatially multiplexed signals increases, but the separation processing is divided into multiple stages. By dividing, the size of hardware can be made relatively small.
- FIG. 3 is a diagram showing a detailed configuration of radio communication apparatus 100.
- transmission signal configuration section 120 has a code section 121, an SZP conversion section 122, interleavers 123-1 to 4, and modulation sections 124-1 to 4.
- the transmission unit 130 includes transmission units 131-1 to 131-4.
- Encoding section 121 receives the transmission data (data sequence z (n)) generated by data generation section 110, performs error correction encoding at a predetermined encoding rate, and performs error correction encoding.
- the transmitted data (encoded data sequence c (n)) is output to the SZP converter 122.
- SZP conversion section 122 receives transmission data after error correction coding, and performs parallel-parallel conversion to generate a parallel data sequence.
- the SZP conversion unit 122 outputs the generated four parallel data sequences to different interleavers 123-1 to -4, respectively.
- Interleaver 123 performs interleaving for each input parallel data sequence, and outputs the interleaved parallel data sequence to modulation section 124.
- Modulating sections 124-1 to 4 perform modulation processing on the input interleaved parallel data sequence
- the bit string is pinned into a modulation symbol on the IQ plane.
- the processed baseband signal is processed !, and the parallel data sequence after the modulation processing is output to the transmission unit 130 as a transmission signal.
- Transmitting section 130 performs predetermined radio transmission processing (DZA conversion, up-conversion, etc.) on each of the transmission signals generated by transmission signal configuration section 120, and transmits the transmission signal after the radio transmission processing. Transmit via different antennas 140.
- predetermined radio transmission processing DZA conversion, up-conversion, etc.
- FIG. 4 is a diagram showing a detailed configuration of radio communication apparatus 200.
- the receiving unit 220 includes receiving units 221-1 to 221-4.
- the second signal separator 240 has two signal separators.
- the received signal processing unit 250 includes a demodulation unit 251—
- Dinterleavers 252-1 to 4 Dinterleavers 252-1 to 4
- PZS conversion unit 253 Dinterleavers 252-1 to 4
- decoding unit 254 decoding unit 254.
- Receiving sections 221—1 to 4 perform the radio reception processing (down-conversion, AZD conversion, etc.) on the spatially multiplexed signals received via the corresponding antennas 210, and the spatially multiplexed signals after the radio reception processing are performed. Is output to the first signal separator 230.
- First signal demultiplexing section 230 performs linear operation on the spatially multiplexed signal (multiplexed number N) from receiving section 220, and consists of a number of transmission signals smaller than the multiplexed number N (transmitted signal of radio communication apparatus 100). The signals are separated into groups of spatially multiplexed signals and output to the second signal separation unit 240.
- Second signal demultiplexing section 240 receives the duplex of the spatially multiplexed signal separated by first signal demultiplexing section 230, and transmits each group of spatially multiplexed signals to each transmission signal included in the spatially multiplexed signal.
- the second signal separation unit 240 has the number of signal separation units 241 corresponding to the number of groups divided by the first signal separation unit 230 (in this embodiment, the signal separation units 2 41-1 and 2 Each signal separation unit 241 separates one group of spatially multiplexed signals into each of the transmission signals included in the spatially multiplexed signal.
- Demodulation section 251 performs demodulation processing corresponding to the modulation method in radio communication apparatus 100 for each transmission signal (transmission signal of radio communication apparatus 100) separated by second signal separation section 240.
- the Dinterleaver 252 performs Dinterleave with a pattern corresponding to the Interleave pattern in the wireless communication apparatus 100 for each transmission signal after demodulation processing.
- PZS conversion section 253 performs parallel-serial conversion on the transmission signal after the Dinterleave, as opposed to serial-parallel conversion in radio communication apparatus 100, and outputs a serial data sequence.
- Decoding section 254 performs a decoding process corresponding to the encoding scheme in radio communication apparatus 100 on the serial data sequence, and outputs received data corresponding to the transmission data of radio communication apparatus 100.
- Data generation unit 110 generates a data sequence z (n) that is transmission data to be transmitted to radio communication apparatus 200.
- the code key unit 121 performs error correction encoding on the data sequence z (n) at a predetermined code rate to generate a coded data sequence c (n).
- a column vector having four elements of the transmission sequence X (k) is expressed as x (k).
- the transmission sequence X (k) that has been converted to a baseband signal is frequency-converted by the transmission unit 130, subjected to band limitation processing, and transmitted from each antenna 140 as a transmission signal that is a high-frequency signal after amplification.
- y (k) is a sequence including the received signal received via each antenna 210 as an element. Is a vector.
- the received signal y (k), that is, the received signal at the discrete time k obtained in the flat fading propagation environment corresponding to the transmission sequence x n (k) from the wireless communication device 100 is expressed as shown in Equation (1). Is done.
- H (k) in the equation (1) indicates a propagation path variation received by the transmission sequence X (k) of the wireless communication device 100 (number of reception antennas of the wireless communication device 200: 4) row X (wireless Number of transmission antennas of communication device 100: 4) A matrix consisting of columns.
- n (k) represents a noise vector having four elements added at the time of reception by antenna 210 of radio communication apparatus 200.
- a matrix element h of i rows and j columns of H (k) is obtained when the signal transmitted from the j th antenna 140 of the radio communication device 100 is received by the i th antenna 210 of the radio communication device 200.
- the propagation path fluctuation in the propagation path is shown.
- the first signal separation unit 230 uses the propagation path fluctuation estimated value B with respect to the propagation path fluctuation H estimated using a known pilot signal transmitted from the wireless communication apparatus 100, and the like to receive the received signal y. Equation (2) is converted to Equation (3) by performing a linear operation on (k).
- the first signal separation unit 230 can use any linear operation that converts Equation (2) into Equation (3). An example of the linear operation to be performed is shown. [0049] First, as Step 1,
- Equation (4) is obtained.
- Equation (5) is obtained.
- Equation (6) is obtained.
- the first signal separation unit 230 obtains the expression represented by the expression (3) by performing the linear calculation in the above steps 1 to 4.
- the transmission sequences X and X are the first group, and X and X are the second dull.
- V and V in Equation (3) include only the first group component (transmission signal).
- V and V contain only the second group of components (transmission signals).
- the first signal separation unit 230 performs a ZF (Zero Forcing) operation on the spatial multiplexing signal with the multiplexing number 4 to remove interference between the two groups, and consists of the two multiplexing signals with the multiplexing number 2. Separated into groups.
- the linear calculation in the above steps 1 to 4 is a ZF (Zero Forcing) calculation, but the calculation is not performed until the final stage of separating all transmission signals included in the spatially multiplexed signal as is normally done. Stop the calculation in front of you.
- the group of spatially multiplexed signals separated by the first signal separation unit 230 is input to the second signal separation unit 240.
- Second signal separation section 240 separates each group of spatially multiplexed signals into transmission signals included in the spatially multiplexed signals. Specifically, V (k) and v (k) of the first group are input to the signal separation unit 241-1, and x (k) and x (k) are input to the signal separation unit 241-1.
- the second group V (k) and v (k) are processed in the same way by the signal separation unit 241-2.
- ZF Zero Forcing
- MMSE Minimum Mean Square Error
- MLD Maximum Likelihood
- Diversity gain (however, it is equivalent to the diversity gain obtained by two multiplex transmissions (2 X 2 spatial multiplex transmission) with two antennas on the transmitting and receiving sides) ) Can be obtained.
- the first signal separation unit 230 that performs the first stage separation processing performs a linear operation on the spatially multiplexed signal and separates it into a group of spatially multiplexed signals composed of a number of transmission signals smaller than the number N of spatially multiplexed signals. And interference between groups is eliminated.
- the interference signal from the other group is subjected to the separation process using the signal removed in the first signal separation unit 230 Therefore, even if MLD is used for signal separation in the second stage, signal point candidates for MLD can be reduced, so realization in hardware is possible. Furthermore, by dividing the separation process into two stages, the diversity gain obtained by 4 ⁇ 4 spatial multiplexing transmission can be obtained, but the diversity gain obtained by 2 ⁇ 2 spatial multiplexing transmission can be obtained. .
- Each transmission signal separated by second signal separation section 240 is demodulated by demodulation section 251, deinterleaved by deinterleaver 252, and input to P / S conversion section 253.
- the signal sequences X (k) and x (k) of the first group are predetermined by the demodulation units 251-1 and 2 respectively.
- Symbol data string power according to the modulation method of the above is converted into a bit data string.
- the bit data sequences obtained by the demodulation units 251-1 and 2 are restored in bit order by the reverse operation of the interleaving performed on the transmission side in the Dinterleavers 252-1 and 252. Similar processing is performed for the second group of signal sequences X (k) and x (k).
- the bit data sequence whose bit order has been restored by the Dinterleaver 252 is parallel-serial converted by the PZS conversion unit 253 and output as a serial data sequence.
- Decoding unit 254 performs a decoding process corresponding to the encoding scheme in radio communication apparatus 100 on the serial data sequence, and outputs received data corresponding to the transmission data of radio communication apparatus 100.
- the separation algorithm in each of the signal separation units 241-1 and 241-2 of the second signal separation unit 240 may be the same between the signal separation units 241-1 and 241-2, or the modulation of the transmission sequence may be performed.
- the number of received signals, etc. they may be fixedly or adaptively changed. For example, MLD is applied when the number of modulation multilevels such as BPSK and QPSK is small, and linear methods such as MMSE can be applied for 16QAM and 64QAM where the number of modulation multilevels is large.
- radio communication apparatus 200 that receives transmission signals transmitted from radio communication apparatus 100 via a plurality of antennas, spatial multiplexing received by each antenna.
- the signal is divided into a plurality of groups, and the first signal separation unit 230 performs signal separation by ZF calculation for removing the inter-group interference with the group as one unit.
- the second signal separation unit 240 separates the transmission signals included in each group.
- a conventional circuit configured for demultiplexing a spatially multiplexed signal having a multiplexing number of 2 can be used as it is.
- the subsequent processing of the first signal demultiplexing unit 230 can apply reception decoding processing for each group, when there are a plurality of transmission sequences, the parallel data is finally converted into serial data. Need to convert.
- the reception decoding process can be performed simultaneously in parallel for each group. For this reason, the input data to the parallel-serial conversion unit 253 is not waited, and a buffer memory for temporarily storing the input data is not provided. For this reason, the data processing delay can be reduced, and the increase in hardware due to the increase in memory can be suppressed.
- the reception characteristics can be better than that obtained by separating the spatial multiplexing signal into transmission signals in one step by using ZF, MMSE, etc.
- the spatial multiplexing signal This is because, when spatial separation is performed by linear processing such as ZF and MMSE, the diversity gain due to reception by multiple antennas is lost, but if this configuration is used, the first signal separation unit 230 This is because, after separating each group, MLD can be used for each group, and diversity gain for two branches can be obtained.
- the MLD is used on the receiving side.
- the ability to obtain optimal reception characteristics without the need for feedback of the channel matrix to the transmitter side and computation of singular value decomposition and eigenvalue decomposition are required, which makes implementation difficult.
- the second signal separation unit 240 is configured to include two signal separation units 241, and the first signal separation unit 230 and the second group use are provided downstream of the first signal separation unit 230.
- a receiving system for receiving a multiplex number 2 spatially multiplexed signal composed of a signal separating unit 241, a demodulating unit 251, and a Dinterleaver 252 is independently provided.
- the signal separation unit 241, the demodulation unit 251, and the Dinterleaver 252 are configured in one system and are not shown in the first signal separation unit 230.
- a receiving system for receiving one multiplexed number 2 spatially multiplexed signal may be configured to be used in a time-division manner between the first group and the second group.
- a circuit configuration for receiving a multiplex number 4 spatially multiplexed signal is realized by adding the first signal separation unit 230 to the circuit configuration for receiving a multiplex number 2 spatially multiplexed signal. It can. Also, in this case, an appropriate index (allowable delay amount of transmission sequence, data type, etc.) is provided based on the QoS of the transmission sequence, and the priority for performing reception processing is assigned to the group after the first signal separation.
- a configuration in which the input to the second signal separation unit 241 is sequentially switched by setting each time is also possible. As a result, an effect of simplifying the configuration of the wireless communication apparatus 200 can be obtained.
- the processing for the spatial multiplexing signal of the first group and the processing for the spatial multiplexing signal of the second group are performed after the processing for the spatial multiplexing signal of one group is completed as described above.
- the group of spatially multiplexed signals that are alternately processed at regular intervals may be switched.
- the first signal separation unit 230 sets X (k) and X (k) to the first group.
- X (k) and X (k) are configured as the second group for signal separation, but are included in the group
- the set of transmission sequences X (k) to be transmitted may be different. For example, if two transmission sequences with the same or close QoS are grouped together and an appropriate signal demultiplexing unit 241 is used based on the QoS of the transmission sequence, the signal demultiplexing unit 241 of the group having a high transmission sequence power with high QoS is used. MMSE can be used for the signal separation unit 241 of the transmission sequence group with low MLD and QoS.
- the following methods 1) and 2) are also available as evaluation criteria for determining the set of transmission sequences X constituting the group in the first signal separation unit 230.
- a combination of multiple methods may be used as an evaluation index.
- the reception SNR or reception SIR for the transmission sequence X (k) transmitted from the nth transmission antenna is used as the evaluation criterion Qn.
- the evaluation criterion based on the received SNR can be obtained by the evaluation criterion Qn shown in the following equation (8).
- trace (X) is an operator that calculates the eigensum of the matrix X.
- SIR evaluation it is possible to apply a method for evaluating the variance of the pilot signal used for channel estimation with respect to the estimated value.
- an appropriate index (permitted delay amount of transmission sequence, data type, etc.) is set and the priority for receiving processing Is set for each transmission sequence, and the allowable delay amount with respect to the transmission delay is used as an evaluation criterion.
- first signal separation section 230 converts X (k) and X (k) into the first group.
- X (k) and X (k) are used as the second group for signal separation.
- the transmission sequences transmitted by remote transmission antennas 140 may be divided into signals so as to be in the same group and separated into signals.
- the first signal separation unit 230 may be configured to separate the signal sequences transmitted from the spatially close antennas 140 into groups so as not to be in the same group. In this way, since the second signal separation unit 240 can reduce the spatial correlation between transmission sequences for performing signal separation, it is possible to improve the performance of signal separation processing when there is a spatial correlation.
- the first signal separation unit 230 sets X (k) and X (k) to the first group.
- the transmission sequences modulated by the same modulation scheme are grouped so as to be in the same group for signal separation. May be. In this way, when MLD is used for the second signal separation unit 240, the modulation scheme can be unified.
- the first signal separation unit sets X (k) and X (k) as the first group, and X
- the wireless communication apparatus 1 transmits transmission sequences modulated by a plurality of modulation schemes
- the transmission sequences modulated by different modulation schemes are grouped so as to be in the same group, and signal separation is performed. May be.
- radio communication apparatus 100 transmits two transmission sequences modulated by 16QAM and two transmission sequences modulated by QPSK simultaneously, one transmission sequence modulated by 16QAM and modulation by QPSK are used. It is divided into a group consisting of one transmission sequence. In this way, when MLD is performed by the second signal separation unit 240, the number of candidate signal points can each be 64. On the other hand, if 16QAM and QPSK are grouped together, MLD with 256 candidate signal points and MLD with 16 candidate signal points are required.
- the present invention can be applied to a wireless communication apparatus that performs spatial multiplexing transmission.
- the first signal separation unit 230 separates the N multiplexed multiplexed signals into L spatial multiplexed signals.
- the number of multiplexed L spatially multiplexed signals is represented by Ml, M2,..., ML, respectively.
- FIG. 7 is a diagram showing a configuration of radio communication apparatus 300 according to Embodiment 2.
- the radio communication device 300 on the reception side creates a replica of the transmission signal on the transmission side (radio communication device 100) from the signal after reception signal processing, specifically, the decoded data sequence. Then, the replica of the transmission signal is multiplied by the propagation path fluctuation to create a replica of the transmission signal at the time of reception, and the interference of the received signal signal canceling the replica of the transmission signal at the time of reception.
- a canceller 370 is provided.
- radio communication apparatus 300 has reception signal processing section 250 (in the figure, reception signal processing section 250B) on the output side of interference canceller 370.
- replica generation section 360 has transmission signal configuration section 120 similar to transmission-side radio communication apparatus 100 and propagation path multiplication section 361.
- the propagation path multiplication unit 361 includes propagation path multiplication units 362-1 to 4 that multiply the propagation signal fluctuation for each transmission signal transmitted from the radio communication device 100 on the transmission side.
- the propagation path multiplier 362 multiplies the replica of the transmission signal created by the transmission signal configuration section 120 based on the signal after reception signal processing in the reception signal processing section 250A by the propagation path fluctuation, Create a replica of the transmitted signal.
- the output R of the propagation path multiplier 362 is also transmitted by the n-th antenna force of the radio communication device 100 on the transmitting side,
- interference canceller 370 has replica subtracting section 371 and diversity combining section 373.
- the replica subtraction unit 371 has a subtracter 372.
- the replica subtraction unit 371 receives a transmission signal other than one transmission signal from the spatially multiplexed signals (y (k) to y (k) in the figure) received by each antenna 210. Subtract replica
- the replica subtracting unit 371 includes replica subtracting units 371-1 to 371-4 for acquiring each transmission signal.
- replica subtraction unit 371-1 is a spatially multiplexed signal received by each antenna 210 (y (k) to y in the figure).
- radio communication apparatus 300 since radio communication apparatus 300 has four antennas, four transmission signals transmitted by the first antenna are obtained.
- the subtracter 372-1 shown in FIG. 10 is transmitted from a spatial multiplexed signal received by the first antenna of the wireless communication apparatus 300 from the other than the first antenna on the transmitting side and is the first on the receiving side.
- the subtraction of the replica of the transmission signal when it is received by the antenna and the transmission signal transmitted from the first antenna on the transmission side and received by the first antenna on the reception side is the diversity combining unit 373 Output to.
- the subtracters 372-2 to 4-4 also transmit the first antenna force on the transmitting side, respectively, and output only transmission signals received by the second, third, and fourth antennas on the receiving side.
- Diversity combining section 373 performs diversity combining for each transmission signal (transmission signal of radio communication apparatus 100), and outputs the transmission signal after diversity combining to reception signal processing section 250B.
- Reception signal processing section 250B performs the same processing as reception signal processing section 250A, and outputs reception data.
- radio communication apparatus 300 having the above configuration
- receiving section 220 outputs a received signal y (k) expressed as a complex digital signal.
- the processing performed by received signal y (k) in first signal separating section 230, second signal separating section 240, and received signal processing section 250A is the same as in the first embodiment.
- the output of reception signal processing section 250A is output as received data to replica generation section 360 without being used as it is.
- Replica generation section 360 creates a replica at the time of transmission signal reception from the output of reception signal processing section 250A. Specifically, the output of reception signal processing section 250A is handled as transmission data, and transmission signal configuration section 120 generates a replica of the transmission signal of radio communication apparatus 100.
- the transmission line multiplier 361 multiplies the transmission signal replica by the propagation path response estimation value B to generate a transmission signal replica R (k).
- the replica R (k) is expressed by the following expression (9) to expression (12).
- Interference canceller 370 performs interference cancellation using received sequence y (k) and replica R (k) mn at the time of transmission signal reception. Specifically, the replica subtraction unit 371-1 subtracts the replica signal when receiving transmission signals other than those related to the transmission sequence X (k) from the reception sequence (1 to 4) by the subtracters 3 72-1 to 4, respectively.
- Diversity combiner 373—1 diversity combines the outputs of subtractors 3 72—1 to 4.
- the diversity combining algorithm is the signal-to-noise power ratio (SNR) after diversity combining. ) To maximize the maximum ratio combining (MRC: Maximum Ratio Combining) and the signal-to-interference noise power ratio (SINR) after diversity combining. At this time, there is no error in replica R (k) mn
- the diversity gain for 4 branches can be obtained.
- the same processing is performed for the replica subtracting unit 371-2 to 4 and the diversity combining unit 373-2 to 4 as well.
- the signal sequence after diversity combining that is, each transmission signal, is subjected to reception signal processing by reception signal processing section 250B and output as reception data.
- reception signal processing section 250B receives reception data from each transmission signal.
- the force described in the configuration in which the interference cancellation process is performed only once is used to generate a replica again from the received data sequence obtained by the interference cancellation process and perform interference multiple times.
- a configuration in which cancellation processing is performed may be adopted. By doing so, the reliability of the replica R (k) is improved as the interference cancellation process is repeated.
- the reception signal processing unit 250B is provided in addition to the reception signal processing unit 250A.
- the output of the interference canceller 370 is received signal processing without the reception signal processing unit 250B. It may be configured to feed back to section 250A.
- the present embodiment it is possible to receive the multiplexing number 4 spatially multiplexed signal transmitted from radio communication apparatus 100 with the configuration using the interference canceller. As a result, it is possible to obtain reception characteristics close to full diversity gain on a realistic hardware scale without using MLD for a spatially multiplexed signal with a multiplexing number of 4.
- the reception characteristics can be improved by repeatedly performing the interference cancellation process even in the conventional configuration in which the interference canceller is used after the spatially multiplexed signal of multiplexing number 4 is directly ZF or MMSE separated.
- inter-group interference is removed by the first signal separation unit 230, and MLD is used by the second signal separation unit 240, so that two branches are separated at the time of the second stage signal separation. Therefore, the replica reliability can be improved compared to the conventional configuration.
- the number of repetitions of the interference canceller is the same, there is an effect that better reception characteristics can be obtained compared to the conventional configuration.
- the radio communication apparatus 300 employs the configuration shown in FIG. 7, but may have the configuration shown in FIG.
- a radio communication apparatus 300A shown in the figure includes a replica generation unit 380 and an interference canceller 385. Unlike the interference canceller 370, the interference canceller 385 subtracts the replica signal from the output v (k) of the first signal separation unit 230.
- replica generation section 380 has propagation path multiplication section 381.
- the propagation path multiplication unit 381 performs propagation path modification for each transmission signal transmitted from the wireless communication device 100 on the transmission side.
- the interference canceller 385 subtracts the output v (k) of the first signal separation unit 230, that is, the spatially multiplexed signal replica signal separated into groups.
- Multipliers 322-1 to 4-4 output only replicas at the time of reception of transmission signals included in the group of spatially multiplexed signals.
- the interference canceller 385 includes a replica subtraction unit 386 and a diversity combining unit 388.
- the replica subtraction unit 386 includes a subtracter 387.
- the replica subtraction unit 386 subtracts a replica at the time of reception of a transmission signal other than one transmission signal from the spatially multiplexed signal separated into groups by the first signal separation unit 230, whereby the one transmission Get the signal.
- the interference canceller 385 includes replica subtracting units 386-1 to 386-4 for acquiring each transmission signal.
- the replica subtraction unit 386-1 uses the first group of spatially multiplexed signals (V (k) and V (k) in the figure) separated by the first signal separation unit 230 as the first on the transmission side. Obtain only transmission signals transmitted by other antennas
- the subtractor 378-1 shown in FIG. 14 is a spatially multiplexed signal belonging to the first group, and is the transmitting side antenna corresponding to the first group (here, the first and second transmitting side antennas). From the first antenna on the transmitting side corresponding to the first group, from the spatially multiplexed signal transmitted from the antenna) and received using the first antenna of the wireless communication device 300A. Subtracting the replica (R (k)) at the time of reception of the transmission signal when received by the first antenna on the transmitting side, the first antenna force on the transmitting side is transmitted,
- the transmission signal received using the first antenna on the receiving side is output to diversity combining section 388.
- the subtractor 387-2 also transmits the first antenna force on the transmitting side, and outputs only the transmission signal received using the second antenna on the receiving side.
- Diversity combining section 388 performs diversity combining for each transmission signal (transmission signal of radio communication apparatus 100), and outputs the transmission signal after diversity combining to reception signal processing section 250B.
- Replica generation section 380 creates a replica at the time of transmission signal reception from the output of reception signal processing section 250A. Specifically, the output of reception signal processing section 250A is handled as transmission data, and a replica of the transmission signal of radio communication apparatus 100 is generated.
- the transmission line multiplier 381 multiplies the replica of the transmission signal by the estimated value D of the converted propagation path response G after the first signal separation, and generates a replica R (k) when the transmission signal is received.
- the replica R (k) is expressed by the following formula (13) to formula (16).
- the interference canceller 385 cancels interference cancellation using the received sequence v (k), that is, the spatially multiplexed signal separated into groups in the first signal separation unit 230, and the replica R (k).
- the replica subtraction unit 386-1 transmits the second antenna force on the transmission side from the reception series V (k) and v (k) in the subtractors 387-1 and 2, Vs group
- Diversity combining section 388-1 combines the outputs of subtractors 387-1, 2 with diversity.
- the diversity combining algorithm is the signal-to-noise power ratio after diversity combining.
- the signal sequence after diversity combining that is, each transmission signal is subjected to reception signal processing by reception signal processing section 250B and output as reception data.
- radio communication apparatus 300 may be configured as shown in FIG. 15 using the configuration shown in FIG.
- Radio communication apparatus 300B shown in the figure has replica generation section 390, interference canceller 395, and second signal separation section 240B.
- Radio communication apparatus 300B reduces the number of multiplexed spatial multiplexed signals by interference canceller 395 in the same manner as first signal separator 230 (here, the number is reduced from 4 to 2), and then the second signal separator. It is configured to perform signal separation with 240B!
- replica generation section 390 has propagation path multiplication section 391.
- the propagation path multiplication unit 391 includes propagation path multiplication units 392-1 to 392-4 that multiply the transmission signal transmitted from the radio communication device 100 on the transmission side by propagation path change.
- the output of interference canceller 395 is a spatially multiplexed signal including transmission signals in the same combination as the output of first signal demultiplexing section 230, it is removed by first signal demultiplexing section 230. Only the replica when the transmission signal is received is output.
- the interference canceller 395 has a replica subtraction unit 396.
- the replica subtraction unit 396 has a subtracter 397.
- the replica subtraction unit 396 belongs to a group different from the group of transmission signals to be detected from the spatially multiplexed signals (y (k) to y (k) in the figure) received by each antenna 210.
- a spatially multiplexed signal including transmission signals of the same combination as the output of the first signal separation unit 230 (V (k) to v (k)) is acquired.
- the replica subtraction unit 396-1 is wireless From the spatially multiplexed signal ((k)) received using the first antenna of communication apparatus 300B, the spatially multiplexed signal (y (k) belonging to a different group (here, the second group) from this spatially multiplexed signal is used. ), Y (k)) receive antennas (the third and fourth antennas)
- radio communication apparatus 300B having the above configuration
- Replica generation section 390 creates a replica at the time of transmission signal reception from the output of reception signal processing section 250A. Specifically, the output of reception signal processing section 250A is handled as transmission data, and a replica of the transmission signal of radio communication apparatus 100 is generated.
- the transmission line multiplier 391 multiplies the transmitter of the transmission signal by the estimated value B of the propagation path response, and generates a replica R (k) when the transmission signal is received.
- the replica R (k) is expressed by the following equations (17) to (20).
- Interference canceller 395 performs interference cancellation using received sequence y (k) and replica R (k) mn at the time of transmission signal reception. Specifically, replica subtraction section 396-1 subtracts the replica signal at the time of reception of the transmission signal (transmission sequence) included in the second group from reception sequence y (k) by subtractor 397, and Output as result ⁇ V (k).
- the second signal separation unit 240B is provided in addition to the second signal separation unit 240A in the wireless communication device 300B.
- the interference canceller is provided without providing the second signal separation unit 240B.
- the output of 395 may be fed back to the second signal separation unit 240A.
- the description has been made on the assumption that the interleave pattern is the same between interleavers 123 1 to 4 of transmitting-side radio communication apparatus 100.
- different patterns may be used. Different interleave patterns can be used for each group.
- the interleaver 123-1 and interleaver 123-2 are pattern A
- the interleaver 123-3 and interleaver 123-4 are pattern B.
- the Dinterleave pattern of the interleaver 252-1 to 4 of the receiver-side radio communication device 300 also uses a pattern corresponding to the interleaver pattern.
- interference canceller 370 performs interference cancellation so as to remove groups of different interleave patterns. Thereafter, the second signal separation unit 240 separates transmission signals (transmission sequences) included in the group. By changing the interleaving pattern in this manner, radio communication apparatus 300 can perform interference cancellation error in a burst manner in which the correlation between the signal to be removed and the signal from which the interference is removed is high when interference is canceled by interference canceller 370. Even in the case of occurrence of interference, interference cancellation errors can be randomized by using different interleave patterns, and the ability of the decoding unit 254 to correct interference cancellation errors can be improved. In addition, transmission signals (transmission sequences) having the same interleave pattern are separated by the second signal separation unit 240, so that occurrence of burst interference cancellation errors can be prevented.
- the interleave pattern may be different for transmission signals (transmission sequences) in the group.
- X interleaves with pattern A
- X with pattern B X with pattern B
- X with pattern B X with pattern B
- the transmission signal (transmission sequence) having the interleave pattern is removed, and the second signal separation unit 240B for the second time separates the transmission signal (transmission sequence signal) having the same interleave pattern.
- the combination of transmission signals (transmission sequences) differs in the first and second signal separation performed by the second signal separation unit 240A and the second signal separation unit 240B. The influence of error propagation can be reduced.
- the radio communication system 10 of the third embodiment includes a radio communication device 400 and a radio communication device 500.
- Radio communication apparatus 400 transmits a transmission signal from each antenna, similarly to radio communication apparatus 100 of the first embodiment.
- each of the transmission signals transmitted from radio communication apparatus 100 corresponds to a parallel data sequence obtained by serial-parallel conversion of one system of transmission data, but the transmission signal transmitted from radio communication apparatus 400 includes transmission signals corresponding to a plurality of space-time coded sequences generated by space-time coding a parallel data sequence of one transmission data.
- radio communication apparatus 400 has transmission signal configuration section 420.
- the transmission signal configuration unit 420 includes an SZP conversion unit 422 and a space-time code key unit 425.
- SZP conversion section 422 receives transmission data after error correction coding, and performs serial-parallel conversion to generate a parallel data sequence. However, unlike the SZP conversion unit 122 of the wireless communication apparatus 100, the SZP conversion unit 422, in the subsequent stage, encodes one information sequence into two space-time code sequences. Since two are arranged, two parallel data series are generated.
- the space-time code key unit 425 receives a parallel data sequence and performs space-time code key processing to generate a space-time code key sequence.
- the baseband signal mapped on the IQ plane by the modulation unit 124 is converted into a block code such as STBC disclosed in B. Vucetic and J. Yuan, 'Space-Time Coding', Wiley. It is assumed that STBC is used to code one information sequence into two space-time code sequences.
- Each of the space-time encoded signals is frequency-converted from the baseband signal in the transmission unit 130, subjected to band limitation processing, and transmitted from each antenna 140 as a high-frequency signal after amplification.
- radio communication apparatus 500 includes second signal separation section 540 and received signal processing section 550.
- Second signal separation section 540 includes space-time decoding section 541.
- First signal demultiplexing section 230 of radio communication apparatus 500 on the transmission side, generates a spatial multiplexing signal including a transmission signal corresponding to a space-time coded sequence that is space-time coded based on the same information sequence. Separate into groups.
- the first signal separation unit 230 since the radio communication device 400 on the transmission side uses space-time coding in two systems, the first signal separation unit 230 performs transmission corresponding to the two systems of the radio communication device 400 on the transmission side. The signal power is separated into groups of spatially multiplexed signals.
- Second signal demultiplexing section 540 has a number of space-time decoding sections 541 corresponding to the number of groups, and the spatially multiplexed signals of each group separated by first signal demultiplexing section 230 are Each transmission signal included in the spatially multiplexed signal is separated and subjected to space-time decoding processing on the transmission signals of each group, and a signal corresponding to the parallel data sequence on the transmission side is output by 550 reception signals.
- Reception signal processing section 550 performs decoding processing and deinterleaving on each of the multiple systems of signals that have been subjected to space-time decoding, and performs parallel-serial conversion by PZS conversion section 553, thereby converting serial data. Data series.
- radio communication apparatus 400 and radio communication apparatus 500 having the above configurations will be described.
- a parallel data sequence of transmission data of one system is further generated by a plurality of space-time code sequences (here, four space-time encodings). Transmission signals corresponding to (sequence) are transmitted from different antennas 140, respectively.
- each of the receivers 221-1 to 4 performs quadrature detection after amplification and frequency conversion, converts them into baseband signals on the IQ plane, and further converts them into complex digital signals using AZD conversion.
- the received signal y (k) that is expressed is output to the first signal separation unit 230.
- y (k) is a column vector including the received signal received via each antenna 210 as an element.
- This received signal y (k) that is, the transmission sequence X from the wireless communication device 400
- a received signal at a discrete time k obtained in a flat fading propagation environment corresponding to n (k) is expressed as in equation (1), as in the first embodiment.
- the first signal separation unit 230 uses the space-time code key unit 425-1 for v tv in equation (3).
- linear calculation is performed to separate the signal into groups of spatially multiplexed signals.
- the space-time decoding units 541-1 and 541-2 decode the encoded sequences encoded by the space-time encoding units 425-1 and 425, respectively.
- Reception signal processing section 550 performs demodulation processing and deinterleaving on each of a plurality of systems that have been subjected to space-time decoding, and PZS conversion section 553 performs parallel-serial conversion to obtain a serial data sequence. Is obtained.
- the space-time code key unit 425 may apply (time axis) space-time code key to continuous symbol data.
- time axis space-time code key
- a two-branch STBC that is a full-rate space-time code
- diversity gain and coding gain can be obtained by the reception method using the first signal separation unit 230 in the wireless communication apparatus 500.
- the ability to apply 4-branch STBC that creates four coded sequences with one space-time coding means can perform space-time code coding that achieves a full rate.
- the transmission rate decreases.
- radio communication apparatus 400 is configured to encode transmission data before being serial-parallel converted by SZP conversion section 422, that is, encoded before the SZP conversion section 422.
- the configuration is such that the key unit 121 is provided, a code key unit for encoding each parallel data sequence may be provided not in the preceding stage of the SZP conversion unit 422 but in the subsequent stage.
- the multi-carrier communication scheme is applied to the radio communication system 10 of the first embodiment.
- radio communication apparatus 600 has OFDM modulation section 620 between transmission signal configuration section 120 and transmission section 130.
- OFDM modulation section 620 includes serial-parallel conversion, IFFT conversion, parallel-serial conversion, and guard interval (GI) insertion for each of the N transmission signals generated by transmission signal configuration section 120. Apply OFDM modulation.
- each transmission signal in the present embodiment is an OFDM signal.
- radio communication apparatus 700 includes OFDM demodulation section 720, first signal separation section 730, and second signal separation section 740.
- OFDM demodulating section 720 includes GI removing means, FFT means, and serial-to-parallel converting means. For each spatially multiplexed signal received by each of antennas 210 and subjected to radio reception processing by receiving section 220, Performs OFDM demodulation processing and outputs the spatially multiplexed signal after OFDM demodulation. [0147] Specifically, OFDM demodulating section 720 performs OFDM demodulation processing for each spatially multiplexed signal received by each antenna 210 and subjected to radio reception processing by receiving section 220, so that each antenna 210 This is output for each symbol (specified by frequency and time) superimposed on each subcarrier of the spatially multiplexed signal received in.
- OFDM demodulation section 721-1 performs OFDM demodulation processing on the spatially multiplexed signal received by antenna 210-1.
- the spatially multiplexed signal received by the antenna 210-1 includes transmission signals transmitted from the antennas 140-1 to 140-4 of the radio communication device 600 on the transmission side.
- Each transmission signal is an OFDM signal, and even if attention is paid to each symbol, symbols transmitted by the respective antennas 140-1 to 140-4 of radio communication apparatus 600 are spatially multiplexed.
- First signal demultiplexing section 730 performs linear operation on the spatially multiplexed signal (multiplexing number N) from receiving section 220, and consists of a number of transmission signals (transmission signal of radio communication apparatus 100) smaller than the multiplexing number N
- the signals are separated into groups of spatially multiplexed signals and output to the second signal separation unit 740.
- the first signal demultiplexing unit 730 performs a linear operation for each symbol that also receives the OFDM demodulating unit power, and also has a symbol power of a number smaller than the multiplex number N (a group of spatial multiplex signals). Output to the second signal separation unit 740.
- Second signal demultiplexing section 740 receives the duplex of the spatially multiplexed signal separated by first signal demultiplexing section 230, and converts each group of spatially multiplexed signals to each transmission signal included in the spatially multiplexed signal. To separate. Specifically, second signal demultiplexing section 740 receives a group of spatially multiplexed symbols and separates it into symbols included in the spatially multiplexed symbols of each group. Each separated symbol is demodulated by demodulator 251 to become bit data.
- data generation unit 110 generates a data sequence zn to be transmitted to radio communication apparatus 700.
- the code key unit 121 performs error correction coding on the data sequence zn at a predetermined coding rate.
- X (k) a column vector with four elements of the transmission sequence X (k) Is expressed as X (k).
- the OFDM modulation unit 620 performs OFDM modulation including serial / parallel conversion, IFFT conversion, parallel / serial conversion, and guard interval (GI) insertion on the transmission sequence X (k) that is set as the baseband signal.
- GI guard interval
- Transmission sequence X (k) subjected to OFDM modulation processing is frequency-converted and subjected to band limitation processing in transmission section 130, and is transmitted from each antenna 140 as a transmission signal that is a high-frequency signal after amplification. .
- y (k) is a column vector including received signals received via the respective antennas 210 as elements.
- OFDM demodulation section 720 performs OFDM demodulation and outputs a symbol data sequence for each of Nc subcarriers.
- the symbol data sequence for each fs-th subcarrier at discrete time k is denoted as Y (k, fs).
- Y (k, fs) is a column vector including the received signal received via each antenna 210 as an element.
- fs l to Nc.
- Symbol signal sequences for different subcarriers from OFDM demodulators 721-1 to 4 having four antennas are input to first signal separator 730.
- fs-th subcarrier data sequence X (k, fs) in each transmission signal (transmission sequence) from wireless communication device 600 the relative delay of the multipath preceding wave power in the propagation path If the time is within the guard interval (GI), the frequency selective fading environment can be handled equivalently to the flat fading propagation environment, so that it is received by the wireless communication device 700.
- the received signal (subcarrier data series) Y (k, fs) is expressed as shown in Equation (21).
- H n (k, fs) represents the propagation path fluctuation received by the symbol data sequence X (k, fs) of the fs-th subcarrier of the n-th transmission antenna
- the number of antennas of device 600 is a matrix consisting of 4) rows X (number of transmitting antennas of wireless communication device 700: 4) columns.
- the matrix element h of i rows and j columns of H (k, fs) indicates that a signal transmitted from the j th antenna 140 of the wireless communication device 600 is received by the i th antenna 210 of the wireless communication device 700. In this case, the channel fluctuation due to the channel of the fs-th subcarrier signal is shown.
- N (k, fs) represents a noise vector having four elements added at the time of reception by the antenna 210 of the wireless communication apparatus 700.
- the first signal separation unit 730 estimates the propagation path variation H (k, fs) of the fs-th subcarrier group, which is estimated using a known pilot signal transmitted from the radio communication apparatus 600. Equation (21) is converted to Equation (22) by performing a linear operation on the fs-th subcarrier data sequence Y (k, fs) using the channel fluctuation estimation value B (k, fs) for Convert to
- the four multiplexed number 4 spatially multiplexed signals can be separated into two groups of spatially multiplexed signals.
- the group of spatially multiplexed signals separated by the first signal separation unit 730 is input to the second signal separation unit 240.
- Second signal demultiplexing section 740 demultiplexes each group of spatially multiplexed signals into transmission signals included in the spatially multiplexed signals. Specifically, spatially multiplexed signals V (k, fs) and V (k, fs) consisting of two first group transmission sequences obtained for each subcarrier are The signal is input to the signal separator 741—1, and the signal separator 741—1 is connected to X (k, fs), X (k, fs)
- V (k, fs) and v (k, fs) are the same in the signal separator 741-2.
- the second signal separation unit 740 uses ZF (Zero Forcing), MMSE (Minimum Mean Square Error), and MLD (Maximum Likelihood Detection) algorithms to separate transmission signals included in each group of spatially multiplexed signals. Such a method can be used. Diversity gain using MLD separation method (however, it corresponds to the diversity gain obtained by two multiplex transmissions (2 X 2 spatial multiplex transmission) with two antennas on the transmitting and receiving sides) Can be obtained.
- ZF Zero Forcing
- MMSE Minimum Mean Square Error
- MLD Maximum Likelihood Detection
- the first signal separation unit 730 performs the separation process using the signal from which the interference signal from the other group is removed. Even if MLD is used for signal separation, it is possible to reduce the number of signal point candidates in MLD, so realization with hardware is possible. Furthermore, by dividing the separation process into two stages, it is possible to obtain a diversity gain obtained by a 2 ⁇ 2 spatial multiplexing transmission that does not reach the diversity gain obtained by a 4 ⁇ 4 spatial multiplexing transmission.
- Each transmission signal separated by second signal separation section 740 is demodulated by demodulation section 251, deinterleaved by deinterleaver 252, and input to P / S conversion section 253.
- demodulation section 251 demodulates the first group of signal sequences X (k, fs) and X (k, fs)
- the separation algorithm in the signal separation unit 741 of the second signal separation unit 740 may be the same between the signal separation units 741, or is fixed according to the number of modulation levels in the transmission sequence, the number of received signals, and the like. May be changed individually or adaptively. For example, MLD is applied when the number of modulation multilevels such as BPSK and QPSK is small, and linear methods such as MMSE can be applied for 16QAM and 64QAM where the number of modulation multilevels is large.
- the first signal demultiplexing unit 730 and the first Two signal separation unit 740 makes it possible to perform signal separation in two stages. As a result, the effects of the first embodiment can be obtained even in a frequency selective fading environment.
- reception characteristics it is possible to obtain better characteristics than the conventional methods (ZF, MMSE) on a realistic hardware scale.
- the first signal separation unit 730 it is possible to extract the transmission sequence (transmission signal) of the wireless communication device 600 even by using batch separation processing by linear processing such as conventional ZF and MMSE.
- linear processing such as conventional ZF and MMSE.
- a space-time code such as STBC or STC is applied, and there are multiple transmission sequences from the same radio communication device 600, the degree of freedom of antenna Is used to suppress interference, and diversity gain and space-time coding gain are impaired.
- frequency-one-space code such as SFBC (Space frequency block coding) using multi-carrier transmission and different subcarriers and different transmission antennas.
- SFBC Space frequency block coding
- the antenna freedom is used to suppress interference because of the property of forming reception weights for separate reception, so that diversity gain, space-time code ⁇ Impair the gain.
- the MLD processing amount for the transmission sequences from all transmission antennas is exponential with respect to the number of transmission sequences and the number of modulation multilevels of the transmission sequences. Since it increases functionally, it is difficult to realize realistic hardware.
- the number of second signal demultiplexing sections 740 is equal to the number of sets of spatially multiplexed signals with multiplex number 2, but an appropriate index (allowable delay of transmission sequence) is set based on the QoS of the transmission sequence. (Amount, data type, etc.) can be provided, the priority for receiving processing is set for each group, and the input to the second signal separation unit 740 is sequentially switched.
- the number of signal demultiplexing units 74 1 can be made smaller than the number of sets of spatially multiplexed signals with 2 multiplexing numbers. In this case, depending on the set, the processing delay until the transmission data is restored increases, but the effect of simplifying the configuration of the wireless communication apparatus 700 can be obtained.
- a receiver circuit that restores a spatial multiplexing signal of multiplex number 4 can be configured simply by adding the first signal separation unit 730 to the receiver circuit that recovers the spatial multiplexing signal of multiplex number 2. can do.
- the transmission data of one system is subjected to a sign key, and the encoded transmission data is subjected to serial-parallel conversion, and N pieces of antennas having the same number as the number of antennas are obtained. A parallel data series was generated.
- one system of transmission data is serial-parallel converted into a number of parallel transmission data smaller than the number of antennas N, and each parallel transmission data is converted into parallel transmission data. The code is applied, and serial-parallel conversion is performed for each encoded parallel transmission data to generate N parallel data sequences having the same number of antennas as a whole.
- radio communication apparatus 800 includes transmission signal configuration section 820.
- the transmission signal configuration unit 820 includes code key units 821-1 and 2, SZP conversion units 822-1 and 2, and an S / P conversion unit 826.
- SZP conversion section 826 receives one line of transmission data generated by data generation section 110, performs serial-parallel conversion on the transmission data, and generates parallel transmission data having a number smaller than the number N of antennas. .
- two parallel transmission data are generated.
- the code unit 821 performs error correction coding using a predetermined code rate for each parallel transmission data, and outputs the parallel transmission data after the error correction code input to the SZP conversion unit 822. To do.
- the SZP conversion unit 822 further performs serial-parallel conversion on each parallel transmission data after the sign key processing, and generates a parallel data sequence having the same number as the number of antennas as a whole.
- two parallel sending Each of the received data is further serial-parallel converted into two parallel data series to generate four parallel data series as a whole. Then, each transmission data sequence is input to interline 123.
- the wireless communication apparatus 900 on the reception side includes a reception signal processing unit 950.
- the received signal processing unit 950 includes PZS conversion units 953-1 and 952, decoding unit 954-1 and 2, and a PZS conversion unit 956.
- the first signal separation unit 230 has the same function as that of the first embodiment, but performs a linear operation on the spatially multiplexed signal (multiplex number N) from the reception unit 220 to obtain the same parallel transmission data. It is separated into a group of spatially multiplexed signals that consist of transmission signal power. That is, first signal demultiplexing section 230 performs a linear operation on the spatially multiplexed signal (multiplexing number N) from receiving section 220, and demultiplexes into groups of spatially multiplexed signals for each code unit.
- P / S conversion section 953 performs parallel-to-serial conversion on the transmission signal after the Dinterleave, and outputs a serial data sequence for each coding unit.
- Decoding unit 954 decodes the serial data sequence for each unit of code from PZS conversion unit 953.
- PZS conversion section 956 further performs parallel-serial conversion on the serial data sequence for each coding unit decoded by decoding section 954, and outputs received data corresponding to transmission data of radio communication apparatus 100 To do.
- radio communication apparatus 800 and radio communication apparatus 900 having the above configuration will be described.
- one system of transmission data generated by the data generation unit 110 is divided into two parallel transmission data.
- Each of the parallel transmission data is encoded by the encoding unit 821-1
- error correction coding is performed at a predetermined coding rate.
- each code data sequence is further divided into two sequences. Then, a transmission signal is generated for each sequence in the same procedure as radio communication apparatus 100 of the first embodiment.
- First signal demultiplexing section 230 performs linear operation on the spatially multiplexed signal (multiplexed number N) from receiving section 220, and demultiplexes into groups of spatially multiplexed signals for each code unit. [0187] In second signal demultiplexing section 240, the spatially multiplexed signals of each group are separated into transmission signals included in the spatially multiplexed signals.
- the transmission signal of the same coding unit is parallel-serial converted into a serial data sequence of the coding unit.
- Each serial data sequence is subjected to error correction decoding processing in decoding units 954-1 and 954-2.
- the error-corrected serial data sequence is combined into one sequence by the PZS converter 956 and output as one system of received data.
- FIG. 23 shows a configuration example of the wireless communication apparatus in this case.
- radio communication apparatus 1000 on the transmission side has transmission signal configuration section 1020.
- This transmission signal configuration section 1020 includes code key sections 1021-1 to 411-4 and an SZP conversion section 1022.
- the SZP conversion unit 1022 performs serial-parallel conversion on one transmission data generated by the data generation unit 110 to generate a parallel data sequence.
- the code key unit 1021 performs a coding process for each parallel data sequence, that is, each parallel data sequence as a code key unit.
- radio communication apparatus 1200 includes data generation section 110-1, data generation section 110-2, transmission signal configuration section 1220-1, and transmission signal configuration section 1220-2. That is, radio communication apparatus 1200 has a plurality of transmission systems (in FIG. 24, two transmission systems (transmission apparatuses 1260-1, 2)), and constitutes a transmission signal from transmission data of a plurality of systems. Send.
- Each transmission signal configuration section 1220 has an encoding section 121. By doing so, it is possible to transmit a plurality of systems of transmission data simultaneously.
- the transmitters 1260-1 and 2 may be independent wireless communication devices, and both wireless communication devices may be subjected to space division multiple access (SDMA) in which signals are transmitted simultaneously.
- SDMA space division multiple access
- radio communication apparatus 1300 includes reception signal processing section 1350-1, and reception signal processing section 1350-2.
- the first signal separation unit 230 is the same as in the first embodiment. Although it has a function, it is separated into groups of spatially multiplexed signals on a transmission system basis.
- Reception signal processing section 1350 performs reception signal processing for each transmission signal corresponding to the transmission system of radio communication apparatus 1200 on the transmission side. In this way, by changing the modulation unit 124, the interleaver 123, and the signal separation unit 241 of the second signal separation unit 240 according to the QoS of the transmission data, efficient wireless transmission can be performed. Become.
- the wireless communication apparatus 1400 includes data generation units 110-1 to 110-4 and transmission signal configuration units 1420-1 to 14-20. That is, radio communication apparatus 1400 has a plurality of transmission systems (in the figure, four transmission systems (transmission apparatuses 1460-1 to 4)) as many as the number of antennas, and transmits from transmission data of a plurality of systems. Configure and send a signal.
- Each transmission signal constituting unit 1420 has a sign key unit 121.
- the transmission devices 1460-1 to 4-4 may be independent wireless communication devices, and the wireless communication devices may be connected by space division multiple access (SDMA) in which signals are transmitted simultaneously.
- SDMA space division multiple access
- the wireless communication device 1500 includes received signal processing units 1550-1 to 1550-4.
- the present embodiment uses single carrier transmission, it can be applied to multicarrier transmission as in the fourth embodiment.
- the above wireless communication devices 800, 900, 1000, 1100, 1200, 1300, 1400, 1500 are configured not to perform space-time coding
- the space-time codes described in Embodiment 3 are used. It is also possible to use a configuration that includes a conversion unit.
- the encoding unit 821-1 includes an encoder 8211 and a puncturing unit 8213 that performs puncturing with the puncture pattern A.
- the encoding unit 821-2 includes an encoder 8212 and a puncture unit 8214 that performs puncture with the puncture pattern B.
- the depuncture patterns of decoding sections 954-1 and 954-2 of receiving-side radio communication apparatus 900 also use patterns corresponding to the puncture patterns. Note that the same applies to the decoding key unit 254-1 and the code key unit 254-2 in the wireless communication apparatus 1300, and a description thereof will be omitted below.
- first signal separation section 230 performs signal separation so as to remove groups of different puncture patterns, that is, to make transmission sequences of the same puncture pattern the same group. Thereafter, the second signal separation unit 240 separates transmission signals (transmission sequences) included in the group. In this way, by making the puncture pattern the same within a group, the signal separation unit 240 and later and the PZS conversion unit 956 are configured independently for each group, and the signal separation unit 240 and later and the PZS conversion unit 956 are each configured. Processing can be executed independently for each group.
- the first signal separation may be performed so that the puncture pattern differs depending on the transmission signal (transmission sequence) in the group.
- xl is divided into transmission sequences punctured by pattern A and x2 is punctured by pattern B
- x3 is divided into transmission sequences punctured by pattern A and x4 is punctured by pattern B.
- FIG. 35 shows another configuration of reception signal processing section 950 in radio communication apparatus 900 in this case, reception signal processing section 950A.
- the first signal separation is divided into groups including different transmission puncture patterns.
- a parallel data sequence is formed in the S / P conversion unit 822 for each puncture pattern.
- the PZS conversion unit includes a parallel data sequence having the same puncture pattern. It is input for each data series.
- radio communication apparatus 1600 of Embodiment 6 includes first signal separation section 1630, second signal separation section 1640, and diversity combining section 1660.
- the first signal separation unit 1630 performs a linear operation on the spatially multiplexed signal (multiplex number N) from the reception unit 220, and from a number of transmission signals (transmission signal of the radio communication device 100) smaller than the multiplex number N. Are separated into groups of spatially multiplexed signals and output to the second signal separation unit 1640.
- first signal demultiplexing section 1630 demultiplexes into spatial multiplexed signal loops related to all combinations of transmission signals, and outputs them to second signal demultiplexing section 1640.
- Second signal demultiplexing section 1640 receives the group of spatially multiplexed signals separated by first signal demultiplexing section 1630, and transmits each group of spatially multiplexed signals to each transmission signal included in the spatially multiplexed signal.
- the second signal separation unit 1640 includes the number of signal separation units 1641 corresponding to the number of groups divided by the first signal separation unit 1630 (in this embodiment, six signal separation units 241-2 to 6). Each signal demultiplexer 1641 separates one group of spatially multiplexed signals into transmission signals included in the spatially multiplexed signal.
- Diversity combining section 1660 performs diversity combining for each transmission signal that is output from second signal separating section 1640. Here, since there are four transmission signals, four diversity combining sections 1661-1 to 4 are prepared.
- radio communication apparatus 1600 having the above configuration
- y (k) is a column vector including the received signal received via each antenna 210 as an element.
- the received signal y (k), that is, the received signal at the discrete time k obtained in the flat fading propagation environment corresponding to the transmission sequence X (k) from the wireless communication device 100 is expressed as in Equation (1).
- First signal separation section 1630 is a known pilot signal transmitted from radio communication apparatus 100.
- Equation (2) can be transformed into Equations (23) to (23) 25)
- the first signal separation unit 1630 can use any linear operation for converting Equation (2) into Equations (23) to (25).
- the conversion can be performed by performing the method shown in Embodiment 1 three times by exchanging the lines of Equation (2).
- V V is only the component of X X
- V V V is only the component of X X
- V contains only the X and X components, and V V contains only the X and X components. 32 1 4 33 34 2 3
- the first signal separation unit 1630 is configured to divide a spatially multiplexed signal having a multiplexing number of 4 into three types of grouping with different transmission signals (transmission sequences) constituting a group by an appropriate linear operation. Provides a function to perform signal separation.
- the group of spatially multiplexed signals separated by first signal separation section 1630 is input to second signal separation section 1640.
- Second signal separation section 1640 separates each group of spatially multiplexed signals into transmission signals included in the spatially multiplexed signals. Specifically, V and V in the first group are separated into X x by the signal separation unit 1641-1. Second group V and v
- Signal separation unit 1641-3 is separated into X x.
- the fourth group, V and V, is the signal component.
- the fifth group, V and V, is the signal separator 16.
- the 6th group V tv is the signal separation unit 1641-2
- the second signal separation unit 1640 uses ZF (Zero Forcing), MMSE (Minimum Mean Square Error), and MLD (Maximum Likelihood Detection) algorithms for separating transmission signals included in each group of spatially multiplexed signals. Etc. can be used. However, diversity gain (however, the diversity that can be obtained by two multiplex transmissions (2 x 2 spatial multiplex transmission) with two antennas on the transmitting and receiving sides) is achieved by using the MLD separation method. Equivalent to the gain).
- Diversity combining section 1660 performs diversity combining for each transmission signal that is output from second signal separation section 1640. Specifically, diversity combining section 1661-1 uses X and X
- Diversity synthesis is performed using X, X, and X.
- Diversity synthesis is performed using X, X, and X.
- Diversity synthesis is performed using X, X, and X. Diversity synthesis algorithm
- MMSE combining diversity that maximizes the power ratio SINR: SignaH: o-Noise plus Interference power Ratio
- selective combining diversity that selects and outputs the most reliable branch, etc.
- the signal sequence after diversity combining that is, each transmission signal, is subjected to reception signal processing by reception signal processing section 250 and output as reception data.
- the multiplex number 4 spatially multiplexed signal is separated into a set of six multiplex number 2 spatially multiplexed signals by the first signal demultiplexing unit 1 630, and then each of the multiplexed signals.
- 2 signal separation section 1640 performs signal separation.
- diversity combining is performed on the output of the second signal separation unit 1640 for the same transmission sequence.
- diversity gain is obtained by combining the outputs of three different second signal separation units 1640 with other multiplexed transmission signals.
- a radio communication device that has a diversity gain different from that of the configuration using the interference cancellation means shown in the second embodiment and that obtains a higher diversity gain than when the configuration of the first embodiment is used. Can do.
- the diversity combining is performed using the signal on the IQ plane output from second signal separation section 1640, but the demodulator demodulates the signal on IQ plane.
- Diversity combining may be performed using likelihood information for each bit obtained later.
- FIG. A configuration example of the wireless communication device in this case is shown in FIG. As shown in the figure, the wireless communication apparatus 1700 has a received signal processing unit 1750. Received signal processing section 1750 has demodulation sections 251-1 to 12-12 and diversity combining sections 17755-1 to 4. With such a configuration, diversity combining can be performed using a different weighting factor for each bit, so that the reception characteristic is improved.
- radio communication apparatus 1800 as shown in FIG. It may be a simple configuration.
- the wireless communication apparatus 1800 includes a reception signal processing unit 1850.
- the radio communication device 1800 uses the demodulation means of the radio communication device 1600 as the Euclidean distance calculation unit 18.
- diversity combining unit 1855 performs diversity combining using Euclidean distance calculated by Euclidean distance calculating unit 1851, and likelihood calculating unit 1857 calculates likelihood information It has become. In this way, diversity combining can be performed in detail using each of the Euclidean distance when the target bit is 1 and the Euclidean distance when it is 0, so that the reception characteristics are improved. Is obtained.
- the candidate points are reduced using the data series after the received signal processing.
- radio communication apparatus 1900 of Embodiment 7 has candidate point reduction signal separation section 1970.
- Candidate point reduction signal separation section 1970 performs candidate point reduction of a received sequence using the signal after reception signal processing in reception signal processing section 250A, specifically, reception data decoded once.
- Candidate point reduction methods are described in the literature (Murakami, Kobayashi, Orihashi, Matsuoka, Examination of likelihood judgment method using partial bit judgment in MIMO system, IEICE, IEICE Technical Report IT2003-90, ISEC2003-130. , WBS2003-208, pp97-102, 2004 (March).
- Candidate point reduction signal demultiplexing section 1970-1 reduces candidate points using the decoded data corresponding to the second group of transmission signals (transmission sequences) from the spatially multiplexed signals received by each antenna 210. After that, signal separation is performed using MLD.
- Candidate point reduction signal demultiplexing section 1970-2 performs candidate point reduction from the spatial multiplexed signal received by each antenna 210 using decoded data corresponding to the first group of transmission signals (transmission sequences).
- radio communication apparatus 1900 having the above configuration
- y (k) is a column vector that includes the received signal received via each antenna 210 as an element.
- This received signal y (k) is a transmission sequence X from radio communication apparatus 100.
- Equation (1) The received signal at discrete time k obtained in a flat fading propagation environment corresponding to (k) is expressed as shown in Equation (1).
- Candidate point reduction signal demultiplexing section 1970 performs candidate point reduction of the received sequence using the signal after reception signal processing in reception signal processing section 250A, that is, reception data decoded once. Specifically, candidate point reduction signal demultiplexing section 1970-1 performs candidate point reduction from the received sequence using decoded data corresponding to the second group of transmission signals (transmission sequence), and then uses MLD. Signal separation is performed. In this way, for example, when 16QAM is used for the modulation scheme, the number of candidate signal points is reduced from 65536 to 256, so MLD can be realized on a realistic hardware scale.
- candidate point reduction signal separation section 1970-2 performs candidate point reduction from the received sequence using the decoded data corresponding to the transmission signal (transmission sequence) of the first group, and then uses ML D. Signal separation.
- received signal processing section 250B the transmission signal (signal sequence) separated in candidate point reduction signal separating section 1970 is used in the same way as received signal processing section 250A. Processing is performed and received data is output. In this way, it is possible to reduce the operation scale of MLD and improve reception quality.
- reception signal processing section 250B is provided in addition to reception signal processing section 250A. However, reception signal processing section 250B is not provided, and the output of candidate point reduction signal separation section 1970 is received. It may be configured to feed back to 250A.
- candidate point reduction signal separation section 1970-1 uses X
- Candidate points are reduced using decoded data corresponding to X, and then the signal is output using MLD.
- the candidate point reduction signal demultiplexing section 1970-2 is configured to reduce the candidate points using the decoded data corresponding to the transmission sequence of the first group in the received sequence power, but multi-level modulation of the transmission sequence is performed.
- a configuration may be adopted in which a part of the bits to be configured is reduced. In this way, it is possible to reduce the operation scale of MLD and improve reception quality.
- the linear calculation in the first signal separation unit is realized by multiplying the weight obtained from the singular value decomposition of the propagation path response matrix.
- radio communication apparatus 2000 includes first signal separation section 2030.
- the first signal separation unit 2030 receives the spatial multiplexing signal from the receiving unit 220 (the number of multiplexing N, N in the figure).
- the first signal separation unit 2030 performs the linear operation by multiplying the weight obtained from the singular value decomposition of the propagation path response matrix.
- radio communication apparatus 2000 having the above configuration
- Transmission signals are transmitted from the Ns antennas of wireless communication apparatus 100, respectively.
- Ns antennas are divided into Nt groups each with M (n) antennas.
- Transmission sequence X (k) indicates a transmission sequence at discrete time k at which the n-th group power is also transmitted to radio terminal apparatus 2000.
- n is a natural number equal to or less than Nt, and when transmitting multiple M (n) transmission sequences X (k) in parallel using multiple antennas (M (n) ⁇ l), The sequence X (k) is also assumed to be an M (n) -dimensional column vector force.
- the number of multiplexed Ns received by each of the antennas 210-l to Nr is Ns.
- Each receiving unit 221-1-4 performs quadrature detection after amplification and frequency conversion, converts it to a baseband signal on the IQ plane, and further receives the received signal y expressed as a complex digital signal using AZD conversion. (k) is output to the first signal separator 2030. Note that the description here assumes that frequency synchronization, phase synchronization, and symbol synchronization have been established.
- the received signal y (k) is a column vector including the received signal received through each antenna 210 as an element.
- This received signal y (k) that is, the received signal corresponding to the transmission sequence X (k) from the radio communication apparatus 100 at a discrete time k ⁇ obtained in a flat fading propagation environment is expressed by Equation (26). It is expressed in
- H represents the propagation path change received by the transmission sequence X (k) in the nth group, (number of radio base station antennas Nr) row X (in the nth group).
- the number of transmitting antennas M (n)) is also a matrix.
- n (k) represents a noise vector having Nr elements added at the time of reception by the antenna 210 of the wireless communication apparatus 2000.
- the row element h of the i-th row and the j-th row of H (k) is the signal when the signal transmitted also by the j-th antenna force of the wireless communication device 100 is received by the i-th antenna 210 of the wireless communication device 2000.
- the propagation path change in the propagation path is shown.
- First signal separation section 2030 is a known pilot signal transmitted from radio communication apparatus 100. Is used to generate group separation weights for separating signals of different group forces using the estimated channel fluctuation values for the estimated channel fluctuations, and perform multiplication on the received signal y (k).
- the group separation weight W for the desired n-th group is the matrix G that also includes the estimated channel fluctuation B force excluding the desired n-th group, as shown in Equation (27).
- Equation (27) For (n) (where j ⁇ n), generate using singular value decomposition.
- Equation (28) the selected left singular vector u is used as a group separation weight matrix W n.
- W Try [M Mi + 1 w Mi + 2 ... w lV .. ⁇ (2 8)
- Each selected left singular vector u is the transmission sequence X (k) from the desired nth group.
- ⁇ number of antennas of wireless communication device Nr
- Equation (29) is a natural number less than Nt.
- Equation (30) can be transformed as shown in Equation (31), and yn (k) Is a signal from which the interference signal component from the other wireless terminal device 100 is completely removed.
- second signal separation section 240 signal separation processing is performed on group separation signal yn (k).
- the group separation signal yn (k) is separated into individual transmission signals (transmission system) by signal separation processing.
- the received signal is separated from the transmission sequence X (k) of the nth group by dividing the channel estimation value B shown in Equation (32) by the user separation weight Wn. This is performed based on the channel estimation value Fn after weight multiplication.
- the second signal separation unit 240 uses ZF (Zero Forcing), MMSE (Minimum Mean Square Error), MLD (Maximum Likelihood Detection), etc. as algorithms for separating the transmission signal from each group of spatially multiplexed signals. Can be used.
- ZF Zero Forcing
- MMSE Minimum Mean Square Error
- MLD Maximum Likelihood Detection
- the signal from which interference signals from other group forces are removed is used for each group, so that signal point candidates for MLD can be reduced. Realization with realistic hardware is possible.
- one method may be fixedly used, or may be adaptively changed according to the number of modulation multi-levels of transmission sequences, the number of received signals, and the like. For example, BPSK, QP If the number of modulation multi-levels is small, MLD is applied. If the number of modulation multi-levels is large, 16QAM, 64QAM, linear methods such as MMSE can be applied.
- Radio communication apparatus 2000 performs demodulation processing, deinterleaving processing, and decoding processing on each signal separated into individual transmission signals (transmission sequences), and reproduces received data.
- the spatially multiplexed signal received by each antenna is received. Divided into multiple groups, with the group as a unit, the signal is extracted as a signal from which interference from other groups has been removed. As a result, the subsequent processing of the first signal separation unit 2030 can apply reception decoding processing for each group. Therefore, when there are multiple transmission sequences, it is necessary to finally convert parallel data to serial data.
- reception decoding processing can be performed in parallel for each group, input data to the parallel-serial conversion means is not waited. Further, in this embodiment, since a buffer memory for temporarily storing input data is not newly provided, the data processing delay can be reduced, and the increase in hardware due to the increase in memory can be suppressed.
- reception characteristics it is possible to obtain better characteristics than conventional methods (ZF, MM SE) with a realistic hardware scale.
- the first signal separation unit 2030 it is possible to extract the transmission sequence when the batch separation process is performed by the conventional linear process such as ZF and MMSE.
- space-time codes such as STBC (Space Time Block Coding) and STTC (Space Time Trellis Coding) are applied, or when multiple transmission sequences from the same group are included, they are received separately. Due to the nature of forming reception weights, the degree of freedom of antennas is used to suppress interference, and the diversity gain and space-time coding gain are impaired.
- the first signal separation unit 2030 instead of the first signal separation unit 2030, it is possible to introduce a batch separation process based on the conventional MLD. However, in this case, the reception characteristics are better than in this embodiment, but if MLD processing is performed on transmission sequences from all transmission antennas, the amount of processing by MLD is reduced to the number of transmission sequences and the number of modulation multilevels. On the other hand, since it increases exponentially, it is difficult to realize realistic hardware. [0252] In the present embodiment, the same number of signal separation units 241 as the number of groups Nt are provided, but appropriate indicators (allowable delay amount of transmission sequence, data type, etc.) are set based on QoS of the transmission sequence.
- the priority for performing reception processing is set for each group and the input to the second signal separation unit 240 is sequentially switched.
- the number of signal separation units 241 can be made smaller than the number of loops, and depending on the user, the processing delay until the transmission data is restored increases, but the effect of simplifying the configuration of the wireless communication device 2000 is achieved. can get.
- radio communication apparatus 2000 adopts the configuration of the interference canceller described in the second embodiment.
- radio communication apparatus 2000 of the present embodiment has a configuration that does not perform space-time code transmission, but may also have a configuration that includes the space-time code transmission section described in Embodiment 3. Good.
- MLD space-time code transmission section
- M (n) multiplexing number
- radio communication apparatus 100 may combine the encoded transmission sequences into one group in the same space-time code section. By doing so, since inter-group interference removal and space-time decoding can be performed independently, it is possible to obtain coding gain and diversity gain by space-time code.
- Embodiment 9 is characterized in that a plurality of transmission signals (signal sequences) subjected to space-time coding are transmitted using a plurality of antennas that are spatially separated from each other.
- radio communication apparatus 2100 includes transmission signal configuration section 2120.
- the transmission signal configuration unit 2120 includes a space-time encoding unit 2125.
- the space-time code unit 2125 receives a parallel data sequence, and performs space-time coding processing to generate a space-time coded sequence.
- the space-time code key unit 2125 transmits the space-time code key sequence as a transmission signal to antennas that are not adjacent to each other, that is, antennas that are spatially separated from each other.
- the baseband signal mapped on the IQ plane by the modulation unit 124 is converted to ST disclosed in B. Vucetic and J. Yuan, 'Space-Time Coding', Wiley. It is assumed that block codes such as BC are applied, and STBC that codes one information sequence into two space-time code sequences is used.
- the transmitting antennas 140-1 to 4 are arranged on a straight line in the order of 140-1, 140-2, 140-3, 140-4.
- the two space-time encoded signals output from the space-time code unit 2125-1 are sent to the transmission units 131-1, 131-3, respectively, and are transmitted to the transmission antennas 140-1, 140-3. Send from.
- the two space-time encoded signals output from the space-time code 2125-2 are sent to the transmission units 131-2 and 131-4, respectively, and the transmission antennas 140-2 and 140-4 are transmitted. Send force.
- transmission antenna 140 of radio communication apparatus 2100 is configured to be arranged on a straight line.
- each transmission antenna 140 is arranged on the top of a polygon or the circumference of a circle.
- the arrangement may be made on the sides of the polygon. Even in such a shape, spatial correlation can be lowered by selecting transmit antennas that are spatially separated and grouping them.
- radio communication apparatus 2200 has transmission signal configuration section 2220.
- the transmission signal configuration unit 2220 includes a space-time code key unit 2125, which performs space-time coding on a part of the parallel data sequences generated from one transmission data and transmits the transmission signal Is generated.
- the space-time code key unit 2125 transmits the space-time code key sequence as a transmission signal to non-adjacent antennas, that is, antennas that are spatially separated from each other.
- the transmission antenna 140-1 and the transmission antenna 140-3 are arranged such that the distance between them is the longest, and the two transmission sequences output from the space-time code unit 2125 are spatially separated. Sent from a transmitting antenna at a distance.
- radio communication apparatus 2300 on the reception side includes first signal separation section 2330 and second signal separation section 2340.
- Second signal separation section 2340 includes space-time decoding section 541.
- First signal separation section 2330 separates the received signal sequence into a set of transmission sequences that are space-time coded and a transmission sequence that is not space-time coded. Thereafter, the space-time decoding unit 541 decodes the transmission sequence subjected to space-time coding. By doing so, it is possible to reduce the spatial correlation between the space-time encoded transmission sequences, and to increase the space-time coding gain.
- radio communication apparatus 2400 has transmission signal configuration section 2420.
- the transmission sequence that has been space-time encoded by the space-time code key unit 2125 is transmitted from the transmission antennas 140-1 and 140-4. By doing so, it is possible to reduce the spatial correlation between space-time encoded transmission sequences, and to increase the space-time coding gain.
- the radio communication device 2500 on the reception side includes a first signal separation unit 2530 and a second signal separation unit 2540.
- First signal separation section 2530 separates the received signal sequence into a set of transmission space sequences that are space-time coded and a transmission sequence that is not space-time coded.
- Second signal demultiplexing section 2540 includes space-time decoding section 541 and signal demultiplexing section 241.
- the second signal demultiplexing section 2540 demultiplexes a set of transmission sequences that have been space-time coded by space-time decoding section 541 and performs signal separation.
- the transmission sequence is separated by space-time coding in the unit 241.
- the transmission sequence that has been space-time encoded in space-time code key unit 2125 includes transmission antenna 140-1, transmission antenna 140-3, and two transmission sequences that are not space-time encoded. May be transmitted using the transmission antenna 140-2 and the transmission antenna 140-3.
- each of the space-time decoding unit 541 and the signal separation unit 241 can perform processing with a low spatial correlation, so that reception characteristics can be improved.
- Embodiment 10 discloses a configuration when the number of reception antennas of the reception-side wireless communication apparatus is larger than the number of transmission antennas of the transmission-side wireless communication apparatus.
- the number of transmitting antennas of the transmitting side wireless communication device is 4 and the number of receiving antennas of the receiving side wireless communication device is 6 as an example.
- FIG. 36 is a diagram showing a configuration of the radio communication device 2600 on the reception side.
- radio communication apparatus 2600 includes reception unit 2620, first signal separation unit 2630, second signal separation unit 2640, and reception signal processing unit 250.
- the reception unit 2620 includes reception units 221-1 to 6-1.
- the second signal separation unit 2640 includes two signal separation units 2641-1 and a signal separation unit 2641-2.
- Received signal processing section 250 includes demodulation sections 251-1 to 25-1, Dinterleavers 252 1 to 4, PZS conversion section 253, and decoding section 254.
- Receiving sections 221—1 to 6 perform the radio reception processing (down-conversion, AZD conversion, etc.) on the spatially multiplexed signals received via the corresponding antennas 210, respectively, and perform the spatial multiplexing signals after the radio reception processing Is output to the first signal separator 2630.
- First signal demultiplexing section 2630 performs a linear operation on the spatially multiplexed signal (multiplex number N) from reception section 2620, and the number of transmission signals smaller than the multiplex number N (transmit signal of radio communication apparatus 100)
- the signals are separated into groups of spatially multiplexed signals that can be used as power, and output to the second signal separation unit 2640.
- Second signal demultiplexing section 2640 receives the group of spatially multiplexed signals separated by first signal demultiplexing section 2630, and transmits each group of spatially multiplexed signals to each transmission signal included in the spatially multiplexed signal.
- the second signal separation unit 2640 includes the number of signal separation units 2641 corresponding to the number of groups divided by the first signal separation unit 2630 (in this embodiment, two signal separation units 2641-1, 1 and 2). )have.
- Each signal separation unit 2641 separates one group of spatially multiplexed signals into transmission signals included in the spatially multiplexed signals.
- Demodulation section 251 performs demodulation processing corresponding to the modulation scheme in radio communication apparatus 100 for each transmission signal (transmission signal of radio communication apparatus 100) separated by second signal separation section 2640.
- the Dinterleaver 252 performs Dinterleave with a pattern corresponding to the Interleave pattern in the wireless communication apparatus 100 for each transmission signal after demodulation processing.
- PZS conversion section 253 performs parallel-to-serial conversion on the transmission signal after the Dinterleave, as opposed to serial-to-parallel conversion in radio communication apparatus 100, and outputs a serial data sequence.
- Decoding section 254 performs a decoding process corresponding to the encoding scheme in radio communication apparatus 100 on the serial data sequence, and outputs received data corresponding to the transmission data of radio communication apparatus 100.
- radio communication apparatus 2600 Next, the operation of radio communication apparatus 2600 will be described.
- the operation on the transmission side is the embodiment. Since it is the same as the description of the wireless communication apparatus 100 in 1, it is omitted.
- the description will be made on the assumption that frequency synchronization, phase synchronization, and symbol synchronization are established.
- the received signal y (k) is a column vector that includes the received signal received via each antenna 210 as an element.
- the received signal y (k), that is, the received signal at the discrete time k obtained in the flat fading propagation environment corresponding to the transmission sequence xn (k) from the wireless communication device 100 is expressed by Equation (33). expressed.
- H (k) in equation (33) indicates the propagation path variation experienced by the transmission sequence X (k) of the wireless communication device 100 (number of reception antennas of the wireless communication device 2600: 6) row X (wireless Number of transmission antennas of communication device 100: 4) A matrix consisting of columns.
- n (k) represents a noise vector having six elements added at the time of reception by antenna 210 of radio communication apparatus 2600.
- the matrix element h of i rows and j columns of H (k) is obtained when the signal transmitted from the j th antenna 140 of the radio communication device 100 is received by the i th antenna 210 of the radio communication device 2600.
- the propagation path fluctuation in the propagation path is shown.
- First signal separator 2630 is a known pilot signal transmitted from radio communication apparatus 100. Equation (34) is converted to Equation (35) by performing a linear operation on the received signal y (k) using the channel variation estimation value B for the channel variation H estimated using To do.
- the first signal separation unit 2630 can use any linear operation for converting Equation (34) into Equation (35).
- Equation (34) Equation (34)
- Equation (35) Equation (35)
- an example of the linear calculation executed by the first signal separation unit 2630 is shown.
- Step 1 First, as Step 1,
- Equation (38) ( I do. As a result, Equation (38) is obtained.
- Equation (39) is obtained.
- the first signal separation unit 2630 performs the linear calculation in the above steps 1 to 4 to obtain the equation
- V, V, and V in Equation (35) represent only the component (transmission signal) of the first group.
- V, V, and V must contain only the second group of components (transmission signals).
- the first signal separation unit 2630 performs a ZF (Zero Forcing) operation on the spatial multiplexing signal of multiplexing number 4 to remove interference between the two groups, and the spatial multiplexing signal power of two multiplexing numbers 2 is also obtained. Is divided into groups. Incidentally, the linear calculation in steps 1 to 4 is a force that is a ZF (Zero Forcing) calculation. As usual, all the transmission signals included in the spatially multiplexed signal are not calculated until the final stage of separation. The calculation is stopped in front.
- ZF Zero Forcing
- the group of spatially multiplexed signals separated by the first signal separation unit 2630 is input to the second signal separation unit 2640.
- Second signal separation section 2640 separates each group of spatially multiplexed signals into transmission signals included in the spatially multiplexed signals. Specifically, V (k), v (k), and v (k) of the first group are input to the signal separation unit 241-1, and the signal separation unit 2641-1
- the second signal separation unit 2640 uses ZF (Zero Forcing), MMSE (Minimum Mean Square Error), MLD (Maximum Likelihood Detection) algorithms to separate transmission signals from each group of spatially multiplexed signals. ) Etc. can be used. However, diversity gain (however, the number of antennas on the transmitting side is 2 and the number of antennas on the receiving side is 3 spatial multiplexing transmissions (2 X 3 spatial multiplexing transmissions) can be obtained by using the MLD separation method. Equivalent to diversity gain).
- first signal demultiplexing section 2630 that performs the first-stage demultiplexing process performs a linear operation on the spatially multiplexed signal to generate a spatially multiplexed signal composed of transmission signals whose number is smaller than the number N of spatially multiplexed signals. Separation into groups and interference between groups is eliminated. Then, the second signal separation unit 2640 that performs the second-stage separation process performs the separation process using the signal from which the interference signal of another group force has been removed in the first signal separation unit 2630. For this reason, even if MLD is used for signal separation in the second stage, signal point candidates for MLD can be reduced, so realization in hardware is possible. Furthermore, by dividing the separation process into two stages, it is possible to obtain a diversity gain obtained by a 2 ⁇ 3 spatial multiplex transmission that does not reach the diversity gain obtained by a 4 ⁇ 6 spatial multiplex transmission.
- Each transmission signal separated in second signal separation section 2640 is demodulated in demodulation section 251, deinterleaved in Dinterleaver 252, and input to PZS conversion section 253. Specifically, the first group of signal sequences X (k) and x (k) are demodulated, respectively.
- the data is converted into a symbol data string power bit data string by a predetermined modulation method.
- the bit order obtained by the demodulating units 251-1 and 2 is restored in bit order by the reverse operation of the interleaving performed on the transmission side in the Dinter Rivers 252-1 and 25-2. Similar processing is performed for the second group of signal sequences X (k) and x (k).
- the bit data sequence whose bit order has been restored by the Dinterleaver 252 is parallel-serial converted by the PZS conversion unit 253 and output as a serial data sequence.
- Decoding unit 254 performs a decoding process corresponding to the encoding scheme in radio communication apparatus 100 on the serial data sequence, and outputs reception data corresponding to the transmission data of radio communication apparatus 100.
- the separation algorithm in the signal separation unit 2641 of the second signal separation unit 2640 may be the same between the signal separation units 2641, or is fixed according to the number of modulation levels of the transmission sequence, the number of received signals, and the like. May be changed individually or adaptively. For example, when BPSK, QPSK, etc., when the number of modulation multilevels is small, MLD is applied, and the number of modulation multilevels is large 16QAM, 64Q In the case of AM, linear methods such as MMSE can be applied.
- radio communication apparatus 2600 that receives transmission signals transmitted from radio communication apparatus 100 via a plurality of antennas, spatially multiplexed signals received by each antenna. Into multiple groups. Next, the first signal separation unit 2630 performs signal separation by ZF calculation to eliminate inter-group interference with a dull as one unit. Thereafter, the second signal separation unit 2640 separates the transmission signals included in each group.
- the subsequent processing of the first signal separation unit 2630 includes, for example, a conventional circuit (2) that is configured to separate a multiplexed number of 2 spatially multiplexed signals using three received sequences.
- X 3 MIMO receiver circuit can be used as it is.
- the subsequent processing of the first signal demultiplexing unit 2630 can apply reception decoding processing for each group, when there are a plurality of transmission sequences, the parallel data is finally converted into serial data. Need to be converted to However, in this embodiment, since receiving and decoding processing can be performed simultaneously in parallel for each group, the input data to the parallel-serial converter 253 is not waited, and new input data is temporarily stored. Since no buffer memory is provided, the data processing delay can be reduced, and the increase in hardware due to the increase in memory can be suppressed.
- reception characteristics better characteristics can be obtained than when the spatially multiplexed signal is separated into transmission signals in one step by ZF, MMSE, or the like. This is because if signal separation is performed using linear processing such as ZF and MMSE, diversity gain due to reception by multiple antennas will be lost.
- the MLD can be used for each group after being separated into groups by the first signal separation unit 2630, so that a diversity gain for two branches can be obtained. .
- MLD is used on the receiving side.
- MLD is used on the receiving side. The ability to obtain optimal reception characteristics without the need for feedback of the channel matrix to the transmitter side and computation of singular value decomposition and eigenvalue decomposition are required, which makes implementation difficult.
- the second signal separation unit 2640 is configured to include two signal separation units 2641, and the first signal separation unit 2630 is followed by the first group and the second group.
- a receiving system (2 ⁇ 3 MIMO receiving system) for receiving a multiplexing number 2 spatially multiplexed signal composed of a signal separating unit 2641, a demodulating unit 251, and a Dinterleaver 252 is provided.
- the present invention is not limited to this, and a configuration in which one 2 ⁇ 3 MIMO reception system is used in a time division manner in the first group and the second group may be used.
- a circuit configuration for receiving a spatially multiplexed signal with a multiplexing number of 4 by adding the first signal separation unit 230 to the 2 X 3 MIMO reception system (4 X 6 MIMO reception circuit) ) Can be realized. Also, in this case, an appropriate index (permitted delay amount of transmission sequence, data type, etc.) is provided based on the QoS of the transmission sequence, and the priority for performing reception processing is set for each group after the first signal separation, A configuration in which the input to the second signal separation unit 2640 is sequentially switched is also possible. Thereby, the effect of simplifying the configuration of the wireless communication device 2600 can be obtained.
- the first signal separation unit 2630 uses x (k) and x (k) as the first group.
- X (k) and X (k) are included in the force group configured to perform signal separation with the second group.
- the set of transmission sequences X (k) to be played may be different. For example, if two transmission sequences with the same or similar QoS are set as the same group and an appropriate signal demultiplexing unit 26 41 is used based on the QoS of the transmission sequence, the signal demultiplexing unit of the group consisting of transmission sequences with high QoS is used. 2641 has low MLD and QoS, and MMSE can be used for the signal separation unit 2641 of the transmission sequence group.
- the first signal demultiplexing unit 2630 may use the method already described in Embodiment 1 as an evaluation criterion for determining a set of transmission sequences x constituting a group.
- the configuration of the receiver is not limited to this. The same applies to the first signal separation unit in the configuration using the interference canceller as described in the second embodiment.
- the present invention can be similarly applied to the first signal separation unit in the configuration using space-time coding as described in the third embodiment and the ninth embodiment.
- the present invention can be similarly applied to the first signal separation unit in the configuration to which the multicarrier communication system as described in the fourth embodiment is applied.
- the present invention can be similarly applied to the first signal separation unit in the configuration in which the number of encoders is different as described in the fifth embodiment.
- the present invention can be similarly applied to the first signal separation unit in the configuration for performing diversity combining as described in the sixth embodiment.
- the present invention can be similarly applied to the first signal separation unit in the configuration that performs signal point reduction as described in the seventh embodiment.
- the present invention can be similarly applied to the first signal separation unit in the configuration based on weight multiplication as described in the eighth embodiment.
- the MIMO receiver and the MIMO communication system of the present invention are useful as being able to reduce the hardware scale even if the number of antennas used for MIMO communication is increased.
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