JP5770558B2 - Receiving device, program, and integrated circuit - Google Patents

Description

  The present invention relates to a technique for improving reception performance of a reception apparatus.

  Standardization of LTE (Long Term Evolution) system, which is a wireless communication system for 3.9th generation mobile phones, has been completed. Recently, LTE-A (LTE-Advanced), which has further evolved LTE system, Standardization is performed as one of wireless communication systems (also referred to as IMT-A or the like).

  In the LTE or LTE-A system, a transmission / reception apparatus includes a plurality of antennas, and a MIMO (Multiple-Input Multiple-Output) multiplexing method is employed in which transmission signals are spatially multiplexed and transmitted.

  In the MIMO multiplexing method, different signals are transmitted from the respective antennas at the same time and the same frequency. 15A to 15D are diagrams illustrating the concept of a general MIMO multiplexing method. In the example of downlink (DL) single user MIMO (SU-MIMO) shown in FIG. 15A, base station apparatus BS1001 spatially multiplexes signals and transmits them to mobile station apparatus MS1001. In the example of downlink multi-user MIMO (MU-MIMO) shown in FIG. 15B, base station apparatus BS1002 spatially multiplexes signals using a plurality of transmission antennas to a plurality of terminal apparatuses MS1002-1 and MS1002-2. Send.

  On the other hand, in the example of uplink SU-MIMO shown in FIG. 15C, mobile station apparatus MS1003 spatially multiplexes and transmits signals to base station apparatus BS1003. In the example of uplink MU-MIMO illustrated in FIG. 15D, mobile station apparatus MS1004-1 and mobile station apparatus MS1004-2 simultaneously transmit different signals to base station apparatus BS1004, and base station apparatus BS1004 transmits the signals. Receiving and detecting the signal of each mobile station apparatus as a MIMO multiplexed signal. This detection is also called multi-user detection.

  Of these, in the example shown in FIGS. 15A, 15C, and 15D, it is necessary to separate a spatially multiplexed signal called MIMO separation on the receiving apparatus side. In the example of FIG. 15B, MIMO separation is not necessarily required if the signal to each mobile station apparatus is one stream. However, in the case of two or more streams, the terminal apparatus performs MIMO as in the examples shown in FIGS. 15A, 15C, and 15D. Separation is required.

  As a method of this MIMO separation, there are a method based on a Minimum Mean Square Error (MMSE) standard and a method based on Maximum Likelihood (ML). Also, as one of the MIMO separation methods, a MIMO separation method based on the turbo principle has been disclosed (for example, Non-Patent Document 1). This is sometimes called turbo equalization or turbo SIC (Soft Interference Cancellation).

  FIG. 16 is a diagram illustrating a configuration example to which the MIMO separation method using the turbo principle is applied. Here, two receiving antennas and two spatially multiplexed signal streams are described. Also, only basic functions will be described, and it is assumed that the transmission apparatus performs transmission after performing general transmission processing such as modulation and error correction coding.

  Reception signals received by the reception antennas 2001-1 and 2001-2 are converted into baseband signals by the radio units 2002-1 and 2002-2 and input to the cancellation unit 2003. The cancel unit 2003 cancels the interference component from the reception signal using the reception signal replica output from the replica generation units 2007-1 and 2007-2. However, since no replica is generated in the first processing, nothing is canceled.

  The received signal output from the cancel unit 2003 is applied with a MIMO separation method such as MMSE in the MIMO separation unit 2004, and an estimated value of the amplitude of each transmission stream is calculated. The output estimated values of the respective streams are converted from modulation symbols into external LLRs (Log Likelihood Ratios) of code bits in the demodulation units 2005-1 and 2005-2. The obtained external LLR of the bits is input to the decoding units 2006-1 and 2006-2, and error correction decoding is performed.

  The external LLR obtained by error correction decoding is input to the replica generation units 2007-1 and 2007-2. In the replica generation units 2007-1 and 2007-2, a reception signal replica is generated and input to the cancellation unit 2003 again. The above process is repeated an arbitrary number of times, and a decoded bit is obtained by making a hard decision on the a posteriori LLR of the information bits output from the decoding units 2006-1 and 2006-2. The information bit represents a bit before error correction coding, and the code bit represents a bit after error correction coding. Also, the external LLR and the posterior LLR have a relationship of posterior LLR = external LLR + advance LLR.

R1-090232 “Comparing performance, complexity and latency of SC-FDMA SIC and OFDM MLD” NSN, Nokia

  As described above, in the MIMO separation method based on the turbo principle, the external information is exchanged by inputting the external LLR to the cancel unit during the iterative process. As a result, in turbo equalization, it is possible to improve reception performance by removing interference as much as possible. However, in practice, when the external information is exchanged, signals from other streams or mobile station devices remain as interference. As described above, the cancellation of the interference component by the external LLR does not sufficiently remove the residual interference.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a receiver, a program, and an integrated circuit that can improve the detection accuracy of MIMO detection and multiuser detection using the turbo principle. And

  (1) In order to achieve the above object, the present invention takes the following measures. That is, the receiving apparatus of the present invention is a receiving apparatus that receives a plurality of spatially multiplexed signals from a transmitting apparatus, performs error correction decoding on the received signal, and performs a post-log LLR (Log Likelihood) of the code bits. Ratio) and an error correction decoding unit that outputs an external LLR of a sign bit, a transmission signal replica generation unit that generates a transmission signal replica based on the a posteriori LLR and the external LLR, and a detection target from the transmission signal replica A replica selection unit that selects a combination of transmission signal replicas, a cancellation unit that removes a reception signal replica created based on the combination of the selected transmission signal replicas from the received signal, and the reception signal replica A MIMO demultiplexing unit that performs MIMO (Multiple-Input Multiple-Output) demultiplexing on the removed signal; And wherein the Rukoto.

  In this manner, a transmission signal replica is generated based on the posterior LLR and the external LLR, a combination of transmission signal replicas is selected from the transmission signal replica according to the detection target, and the transmission signal replica selected from the received signal is selected. Since the received signal replica created based on the combination is removed, the detection accuracy can be improved, and as a result, the reception performance can be improved.

  (2) In the receiving apparatus of the present invention, the replica selection unit sets a transmission signal replica to be detected as a transmission signal replica generated from the external LLR, and sets a transmission signal replica other than the detection target as the thing. A transmission signal replica generated from the rear LLR is used.

  As described above, the transmission signal replica to be detected is a transmission signal replica generated from the external LLR, and the transmission signal replica other than the detection target is a transmission signal replica generated from the subsequent LLR. It is possible to improve detection accuracy by performing repetitive processing based on the original turbo principle for the signal and using a received signal replica generated from the posterior LLR for buffering between streams. As a result, reception performance can be improved.

  (3) In addition, the receiving apparatus of the present invention is characterized in that a single user MIMO signal is received from the transmitting apparatus.

  With this configuration, it is possible to improve reception performance when a single user MIMO signal is received.

  (4) Moreover, the receiving apparatus of this invention receives the signal of multiuser MIMO from the said transmitter.

  With this configuration, it is possible to improve reception performance when a multi-user MIMO signal is received.

  (5) Further, in the receiving device of the present invention, the error correction decoding unit demodulates the post-code LLR and the post-code LLR of the code bit based on the LLR obtained by demodulating the received signal. The external LLR of the sign bit obtained by subtracting the LLR obtained in this way is output.

  In this way, the error correction decoding unit obtains by subtracting the LLR obtained by demodulating the posterior LLR of the code bit and the posterior LLR of the code bit based on the LLR obtained by demodulating the received signal. Since the external LLR of the sign bit to be output is output, the signal to be detected is repeatedly processed based on the original turbo principle, and the received signal replica generated from the posterior LLR is used for buffering between streams. By using it, it becomes possible to improve detection accuracy. As a result, reception performance can be improved.

  (6) A receiving apparatus according to the present invention is a receiving apparatus that receives a plurality of signals overlapped by some subcarriers from a transmitting apparatus, an equalization unit that equalizes distortion of a propagation path, and the reception An error correction decoding unit that performs error correction decoding on the received signal and outputs an a posteriori LLR (Log Likelihood Ratio) of the code bit and an external LLR of the code bit, and a transmission signal based on the a posteriori LLR and the external LLR A transmission signal replica generation unit that generates a replica; and a cancellation unit that removes a reception signal replica created based on a combination of the generated transmission signal replicas from the received signal, the transmission signal replica generation unit The transmission signal replica to be detected is a transmission signal replica generated from the external LLR, and the transmission signal replica other than the detection target is the above-described transmission signal replica. Characterized by a transmission signal replica generated from the rear LLR.

  As described above, since the post LLR and the external LLR are selectively used, it is possible to improve the reception performance.

  (7) A program according to the present invention is a program for a receiving device that receives a plurality of spatially multiplexed signals from a transmitting device, performs error correction decoding on the received signal, A process of outputting an LLR (Log Likelihood Ratio) and an external LLR of a sign bit, a process of generating a transmission signal replica based on the posterior LLR and the external LLR, and a transmission from the transmission signal replica according to a detection target A process of selecting a combination of signal replicas, a process of removing a received signal replica created based on the combination of the selected transmission signal replicas from the received signal, and a signal from which the received signal replica has been removed To perform a series of processes of performing MIMO (Multiple-Input Multiple-Output) separation and And butterflies.

  In this manner, a transmission signal replica is generated based on the posterior LLR and the external LLR, a combination of transmission signal replicas is selected from the transmission signal replica according to the detection target, and the transmission signal replica selected from the received signal is selected. Since the received signal replica created based on the combination is removed, the detection accuracy can be improved, and as a result, the reception performance can be improved.

  (8) Further, the program of the present invention is a program for a receiving device that receives a plurality of signals overlapped by some subcarriers from a transmitting device, the process for equalizing distortion of a propagation path, and the received Error correction decoding is performed on the signal, and a transmission signal replica is generated based on a process of outputting an a posteriori LLR (Log Likelihood Ratio) of the code bit and an external LLR of the code bit, and the a posteriori LLR and the external LLR Processing, processing for removing the received signal replica created based on the combination of the generated transmission signal replicas from the received signal, and a transmission signal replica generated from the external LLR as a transmission signal replica to be detected And a series of processes of making a transmission signal replica other than the detection target a transmission signal replica generated from the posterior LLR. And characterized by causing a computer to execute the.

  As described above, since the post LLR and the external LLR are selectively used, it is possible to improve the reception performance.

  (9) An integrated circuit according to the present invention is an integrated circuit that is mounted on a receiving device, thereby causing the receiving device to perform a plurality of functions, and receives a plurality of spatially multiplexed signals from the transmitting device. A function, a function of performing error correction decoding on the received signal, and outputting a post-log LLI (Log Likelihood Ratio) of the code bit and an external LLR of the code bit, and the post-LLR and the external LLR, Created based on a function of generating a transmission signal replica, a function of selecting a combination of transmission signal replicas from the transmission signal replica according to a detection target, and a combination of the selected transmission signal replicas from the received signal The function of removing received signal replicas and the signal from which the received signal replicas are removed are MIMO (Multiple-Input Multiple-Output) components. Characterized in that to exert function and a set of functions of the receiving apparatus that performs.

  In this manner, a transmission signal replica is generated based on the posterior LLR and the external LLR, a combination of transmission signal replicas is selected from the transmission signal replica according to the detection target, and the transmission signal replica selected from the received signal is selected. Since the received signal replica created based on the combination is removed, the detection accuracy can be improved, and as a result, the reception performance can be improved.

  (10) Moreover, the integrated circuit of the present invention is an integrated circuit that causes the receiving device to perform a plurality of functions by being mounted on the receiving device, and includes a plurality of overlapping sub-carriers from the transmitting device. A function of receiving a signal, a function of equalizing propagation path distortion, and error correction decoding on the received signal, and outputting a post-log LLI (Log Likelihood Ratio) of the code bit and an external LLR of the code bit And a function of generating a transmission signal replica based on the posterior LLR and the external LLR, and a reception signal replica created based on a combination of the generated transmission signal replica from the received signal is removed. Function and a transmission signal replica to be detected as a transmission signal replica generated from the external LLR, and a transmission signal replica other than the detection target to Characterized in that to exert the function of a transmission signal replica generated from the posterior LLR, a series of functions of the receiving device.

  As described above, since the post LLR and the external LLR are selectively used, it is possible to improve the reception performance.

  According to the present invention, it is possible to improve the detection accuracy of MIMO detection and multiuser detection using the turbo principle.

It is a figure which shows an example of the radio | wireless communications system which concerns on 1st Embodiment. It is a conceptual diagram which shows the example which allocates the transmission signal transmitted from each transmitting antenna in 1st Embodiment to a subcarrier. It is a block diagram which shows an example of a structure of a 1st communication apparatus (mobile station apparatus). It is a block diagram which shows an example of a 2nd communication apparatus (base station apparatus). It is a block diagram which shows an example of a structure of a decoding part. It is a block diagram which shows the structure of a cancellation part. It is a flowchart which shows the operation example of a replica selection part. Block error rate with respect to the average received Es / N _0: a (BLER Block Error Rate) graphs showing the characteristics. It is a figure which shows an example of the radio | wireless communications system which concerns on 2nd Embodiment. It is a conceptual diagram which shows the example which allocates the frequency signal of each 1st communication apparatus to a subcarrier in 2nd Embodiment. It is a block diagram which shows an example of a structure of the 1st communication apparatus in case there is one transmission antenna. It is a block diagram which shows an example of a structure of a 2nd communication apparatus. It is a conceptual diagram which shows the example of subcarrier allocation in 3rd Embodiment. It is a block diagram which shows an example of a structure of a 2nd communication apparatus. It is a figure which shows the concept of a general MIMO multiplexing method. It is a figure which shows the concept of a general MIMO multiplexing method. It is a figure which shows the concept of a general MIMO multiplexing method. It is a figure which shows the concept of a general MIMO multiplexing method. It is a figure which shows the general structural example to which the MIMO separation method using a turbo principle is applied.

  Embodiments of the present invention will be described below with reference to the drawings. In the following embodiment, a case where the number of transmission / reception antennas is two as an example of SU-MIMO, and a case where the number of transmission antennas is one and the number of reception antennas is two as an example of MU-MIMO will be described. The application of the present invention is not limited to these.

  Moreover, although the following embodiment demonstrates the example using single carrier frequency division multiple access (SC-FDMA: Single Carrier Frequency Division Multiple Access), Clustered DFT-S-OFDMA (Discrete Fourier Transform Spread Orthogonal Frequency Division Multiple Access) Access), or a multi-carrier scheme such as orthogonal frequency division multiple access (OFDMA) or multi-carrier code division multiple access (CDMA).

  In addition, a spatial multiplexing scheme in which subcarriers with the same frequency are allocated between antennas, or a scheme in which subcarriers with the same frequency are allocated between users may be used, or only a part of allocated subcarriers may have the same frequency. Alternatively, a method in which other subcarriers have different frequencies may be used.

[First Embodiment]
FIG. 1 is a diagram illustrating an example of a wireless communication system applied to SU-MIMO. In this embodiment, an example of SU-MIMO will be described. In the example illustrated in FIG. 1, the wireless communication system according to the present embodiment includes a first communication device 1 and a second communication device 2. The first communication device 1 includes two transmission antennas, and the second communication device 2 includes two reception antennas. In the example of FIG. 1, communication is performed by spatially multiplexing two different signals (streams) using two transmission / reception antennas.

  FIG. 2 is a conceptual diagram illustrating an example in which a transmission signal transmitted from each transmission antenna is assigned to a subcarrier in SU-MIMO. The example shown in FIG. 2 will be described on the premise of a single carrier. Allocation examples A1 and A2 show cases where frequency signals transmitted from the respective transmission antennas are allocated to the same subcarrier. Allocation examples A3 and A4 are identical in frequency signals transmitted from the respective transmission antennas only to some subcarriers. This shows a case where the subcarriers are allocated.

  In allocation examples A1 and A3, SC-FDMA is used in which signals are continuously arranged on the frequency axis. In allocation examples A2 and A4, the frequency signal is divided into a plurality of clusters, and each cluster is discontinuous on the frequency axis. The deployed Clustered DFT-S-OFDMA is used. The application range of this embodiment includes all these assignments, and also includes multi-carrier schemes such as OFDM and MC-CDMA.

  FIG. 3 is a block diagram showing an example of the configuration of the first communication apparatus (mobile station apparatus). The first communication device includes two codewords (encoded blocks to be transmitted), but the number of codewords provided may be one or three or more. Moreover, although the example applied to an uplink is demonstrated unless there is particular notice, it is applicable also to a downlink.

  First, a control signal from a second communication device received by a receiving antenna (not shown) is down-converted into a baseband signal by the radio unit 21 and detected as control information by the control information detection unit 22. The detected control information includes orthogonal codes for orthogonalizing reference signals between transmission antennas, information on sequences for generating reference signals, and resource allocation information indicating which subcarriers in the system band are used for transmission. As well as information on modulation schemes and coding rates (MCS: Modulation and Coding Schemes).

  Based on these pieces of information, the first communication device performs transmission processing. First, the encoding units 11-1 and 11-2 encode information bits, and the modulation units 12-1 and 12-2 convert the code bits into QPSK (Quaternary Phase Shift Keying), 16QAM (Quadrature Amplitude Modulation), 64QAM, and the like. Modulate into modulation symbols.

  The layer mapping unit 13 divides the modulation symbol into each stream (also referred to as a layer). Further, the DFT units 14-1 and 14-2 convert the respective signals into frequency signals. The frequency mapping units 15-1 and 15-2 arrange the converted frequency signals on the subcarriers based on the frequency allocation information. IFFT (Inverse Fast Fourier Transform) units 16-1 and 16-2 convert frequency signals arranged on subcarriers into time signals, and reference signal multiplexing units 17-1 and 17-2 receive time signals. The

  The reference signal multiplexing units 17-1 and 17-2 generate a reference signal based on information related to the reference signal, and multiplex it with the time signal output from the IFFT units 16-1 and 16-2. The CP insertion units 18-1 and 18-2 insert a cyclic prefix (CP) into the time signal, the radio units 19-1 and 19-2 upconvert to radio frequencies, and transmit from each transmission antenna. To do.

  FIG. 4 is a block diagram illustrating an example of the second communication apparatus (base station apparatus). The radio unit 31-1 and the radio unit 31-2 down-convert the received signals received by the two receiving antennas into baseband signals. CP removing sections 32-1 and 32-2 remove CPs from the obtained baseband signals, and reference signal separating sections 33-1 and 33-2 separate reference signals. The separated reference signal is input to the propagation path estimation unit 43, and the propagation path estimation unit 43 estimates the propagation path characteristic between each transmission antenna and each reception antenna used for transmission of the separated reference signal. Use.

  On the other hand, the FFT units 34-1 and 34-2 convert the received signal from which the reference signal is separated into a frequency signal. The obtained frequency signal is input to the cancel unit 35, and the cancel unit 35 cancels the reception signal output from the reception signal replica generation unit 42 from the obtained frequency signal. The MIMO separation unit 36 performs MIMO separation on the reception signal after canceling the reception signal replica. Assuming that the propagation path matrix in the k-th subcarrier estimated by the propagation path estimation unit 43 is H (k), when performing MIMO separation based on the MMSE standard, the weight (weight) to be multiplied with the received signal is expressed.

Where W (k) is a weight to multiply the received signal vector of the kth subcarrier, I is a unit matrix of the number of receiving antennas × the number of receiving antennas, σ ² is a variance of noise including unknown interference such as inter-cell interference, x ^H represents an adjoint matrix obtained by Hermitian transposition of the matrix (vector) x. Δ represents a diagonal matrix in which the residual energy of the signal after cancellation is arranged in a diagonal component. Note that H (k) is expressed by the following equation in the case of 2 × 2 MIMO.

However, Hnm (k) represents a propagation path characteristic represented by a complex number from the mth transmission antenna to the nth reception antenna.

  The frequency demapping units 37-1 and 37-2 extract (demapping) only the assigned subcarriers from the estimated symbols of the respective frequencies separated as described above, and IDFT units 38-1 and 38-2. Converts the extracted subcarriers into time signals, and the demodulation units 39-1 and 39-2 convert the converted time signals into LLRs of code bits.

  The LLR of the obtained code bit is input to the decoding units 40-1 and 40-2. Decoding sections 40-1 and 40-2 calculate the a posteriori LLR of the information bits, the a posteriori LLR of the code bits, and the external LLR. Further, the a posteriori LLR of the information bit is decoded by a hard decision, and the a posteriori LLR and the external LLR of the code bit are input to the replica generation units 41-1 and 41-2, respectively. The replica generation units 41-1 and 41-2 generate a soft replica having an amplitude proportional to the reliability by using the a posteriori LLR and the external LLR of the sign bit.

  The replica selection unit 50 selects a combination of the generated soft replica and each transmission stream and inputs the combination to the reception signal replica generation unit 42. At this time, the combination of the posterior LLR, the external LLR, and the first and second transmission antennas is [a replica of the first transmission stream generated from the external LLR, a replica of the second transmission stream generated from the posterior LLR. ] And [a replica of the first transmission stream generated from the posterior LLR, a replica of the second transmission stream generated from the external LLR]. Details of the operation of the replica selection unit 50 will be described later.

  Thus, the generated soft replicas are respectively input to the reception signal replica generation unit 42. The reception signal replica generation unit 42 generates reception signal replicas represented by the following equations (3) and (4) based on the propagation path characteristics estimated from the propagation path estimation unit 43.

In the above equation, H (k) represents the channel characteristic of the kth subcarrier. Sep and soft are generated from a replica generated from the external LLR of the code bit transmitted from the first transmission antenna of the first communication device and a posterior LLR of the code bit transmitted from the second transmission antenna. This represents a soft replica vector in which replicas are arranged. Similarly, Spe and soft are generated from the replica generated from the a posteriori LLR of the code bit transmitted from the first transmission antenna of the first communication apparatus and the external LLR of the code bit transmitted from the second transmission antenna. Represents a soft replica vector in which the replicas are arranged.

  Rep (k) and Spe (k) are reception signal replica vectors generated from the respective soft replicas, and represent combinations of transmission streams output from the replica selection unit 50. Note that the vector size of the equations (3) and (4) is (the number of reception antennas) × 1. These are input to the cancel unit 35.

  Thereafter, as the processing from the cancel unit 35 to the reception signal replica generation unit 42, the same processing is repeated an arbitrary number of times, and finally, the a posteriori LLR of the information bit is hard-decided to obtain a decoded bit.

  Next, the cancellation unit 35 and the decoding unit 40-1 or 40-2 will be described. An essential feature of the present invention resides in the operation of the cancel unit 35. First, the decoding unit 40-1 or 40-2 will be described. FIG. 5 is a block diagram illustrating an example of the configuration of the decoding unit 40-1. Using the LLR input to the decoding unit 40-1, the decoding processing unit 45-1 obtains the posterior LLR of the information bits and the posterior LLR of the code bits by estimating the maximum posterior probability (Maximum A Posteriori probability). Further, the subtracting unit 46-1 obtains the external LLR of the code bit by subtracting the a posteriori LLR of the code bit output from the decoding processing unit 45-1 from the a posteriori LLR of the code bit obtained from the demodulating unit 39-1. .

  Next, the cancel unit 35 will be described. FIG. 6 is a block diagram illustrating a configuration of the cancel unit 35. The cancellation unit 35 receives the reception signal from each reception antenna and the reception signal replica generated by the reception signal replica generation unit 42. Then, the cancel unit 35 subtracts the received signal replica from the received signal.

  As shown in FIG. 6, the reception signal replica generated by the reception signal replica generation unit 42 is input to the replica subtraction unit 51-1. As the input, the received signal replica generated from the external LLR for the signal transmitted from the first transmitting antenna, and the received signal replica generated from the posterior LLR for the signal transmitted from the second transmitting antenna are replica subtracted. Input to the unit 51-1.

  Similarly, the input to the replica subtracting unit 51-2 is received signal replica generated from the posterior LLR with respect to the signal transmitted from the first transmitting antenna, and from the external LLR with respect to the signal transmitted from the second transmitting antenna. The generated reception signal replica is input to the replica subtraction unit 51-2.

  Next, the replica subtraction unit 51-1 will be described. The replica subtraction unit 51-1 performs a cancellation process on the received signal replica input from the received signal, and outputs the received signal as a received signal for detecting the transmission stream 1. Even when the number of streams is three or more, a replica of the transmission stream to be detected is a received signal replica generated from the external LLR, and the rest is a received signal replica generated from the subsequent LLR.

  By such processing, the signal to be detected is repeated based on the original turbo principle, and the received signal replica generated from the posterior LLR is used for inter-stream interference. As a result, detection accuracy can be increased and reception performance is improved.

  Next, an operation example of the replica selection unit 50 will be described. FIG. 7 is a flowchart illustrating an operation example of the replica selection unit 50. First, the index m of the antenna to be detected is set to 0 (step S1). Then, 1 is added to the numerical value of the index m (step S2). Next, it is determined whether m is larger than the number of transmission antennas (step S3).

  If m is larger than the number of transmission antennas (or codewords), a replica generated from the external LLR of the mth antenna (or codeword) is selected (step S4). A replica generated from the posterior LLR other than the m-th antenna (or codeword) is selected, and the replica selection result when the m-th antenna (or codeword) is set as a detection target (step S5), step S2 Return to.

  This series of processing is performed for all the transmission antennas (or codewords) to be detected, and a replica is selected. When the value of m exceeds the number of transmission antennas in step S3, the selection processing ends. . In this way, the reception performance is improved by generating a reception signal replica using the obtained soft replica and subtracting the reception signal replica from the reception signal.

Figure 8 is a block error rate with respect to the average received Es / N _0: a (BLER Block Error Rate) graphs showing the characteristics. FIG. 8 shows the block error rate characteristics of 16QAM and 64QAM when a turbo code with a coding rate of 8/9 is used. In the example shown in FIG. 8, the 4 × 4 SU-MIMO characteristic is targeted.

  A curve group 91 represents a BLER characteristic of 16QAM, a curve 92 is a BLER characteristic by a reception method based on a conventional turbo principle, a curve 93 is a reception method of the present application, and a curve 94 is a reception method without repetition processing in the case of 16QAM. BLER characteristics are represented. A curve group 95 represents a BLER characteristic of 64QAM, a curve 96 represents a BLER characteristic by a reception method based on a conventional turbo principle, and a curve 97 represents a BLER characteristic by a reception method of the present invention. A curve 98 represents a reception method without repetition processing in the case of 64QAM. As shown in FIG. 8, it can be seen that the detection accuracy can be improved by the receiving method of the present invention.

[Second Embodiment]
As this embodiment, a case where the present invention is applied to MU-MIMO will be described. FIG. 9 is a diagram illustrating an example of a wireless communication system applied to MU-MIMO. In FIG. 9, two first communication devices 61-1 and 61-2 (mobile station devices) transmit at the same time, and a second communication device 62 (base station device) receives and separates the two by MIMO separation. Each of the signals transmitted by the first communication devices 61-1 and 61-2 is detected.

  FIG. 10 is a conceptual diagram illustrating an example of assigning the frequency signal of each first communication device to subcarriers in MU-MIMO. In the example of FIG. 10, it is assumed that a plurality of first communication devices 61-1 and 61-2 having one transmission antenna transmit simultaneously. This embodiment includes the same concept as subcarrier allocation examples B1 to B4.

  FIG. 11 is a block diagram illustrating an example of the configuration of the first communication device when there is one transmission antenna. The first communication device on the transmission side down-converts a control signal received by a receiving antenna (not shown) into a baseband signal by the radio unit 79, and transmits all control information necessary for transmission processing by the control information detection unit 80. To detect.

  On the other hand, the encoding unit 71 performs error correction encoding on the information bits to be transmitted based on the encoding rate specified by the control information. Then, the modulation unit 72 converts information bits into modulation symbols based on the modulation scheme specified by the control information. The DFT unit 73 converts the modulation symbol into a frequency signal.

  The frequency mapping unit 74 assigns the frequency signal to the subcarrier designated by the control information, and the IFFT unit 75 converts the signal assigned to the subcarrier into a time signal. The reference signal multiplexing unit 76 multiplexes the reference signal into a time signal, and the CP insertion unit 77 inserts a CP into the multiplexed signal. The radio unit 78 up-converts the signal with the CP inserted into a radio frequency and transmits it from the transmission antenna.

  FIG. 12 is a block diagram illustrating an example of the configuration of the second communication device on the receiving side. The configuration of the second communication device is the same as that of the second communication device in the first embodiment. In the example illustrated in FIG. 12, the decoding unit 40-1 and the decoding unit 40-2 have a function of detecting signals transmitted from the first communication apparatuses from the frequency demapping units 37-1 and 37-2. doing. By applying such processing, reception performance is improved.

[Third Embodiment]
As the present embodiment, a case will be described in which the present invention is applied to an access technology utilizing the characteristics of turbo equalization. FIG. 13 is a conceptual diagram illustrating an example of subcarrier allocation in a case where the feature of turbo equalization is utilized. An assignment example C1 shows assignment based on SC-FDMA, and an assignment example C2 shows assignment based on Clustered DFT-S-OFDM. The transmission process of the first communication apparatus is basically the same as that in the above embodiment, but the MIMO process is not assumed and the number of reception antennas may be one. Such a method may be called SORM (Spectrum-Overlapped Resource Management) or frequency overlap multiple access.

  This reception method is basically premised on iterative processing based on the turbo principle, and even when the number of spatial multiplexing exceeds the number of reception antennas, multi-user detection that detects signals of at least all first communication devices is applied. If possible, reception processing can be performed.

  FIG. 14 is a block diagram illustrating an example of the configuration of the second communication device on the receiving side. In the example illustrated in FIG. 14, two first communication devices transmit by assigning the same subcarriers with some subcarriers, and the second communication device receives with one receiving antenna. Radio section 101 down-converts the received signal, and CP removal section 102 removes the CP from the down-converted signal.

  The reference signal separation unit 103 separates the reference signal transmitted from the first communication device from the reception signal and inputs the reference signal to the propagation path estimation unit 113. The propagation path estimation unit 113 estimates the propagation path characteristics from the reference signals transmitted from all the first communication devices, and inputs the propagation path characteristics to the reception signal replica generation units 112-1 and 112-1 and the equalization unit 106. .

  On the other hand, the FFT unit 104 converts the received signal from which the reference signal is separated into a frequency signal. The cancel unit 105 cancels the reception signal replica generated by the reception signal replica generation units 112-1 and 112-2 from the reception signal converted into the frequency signal. The equalization unit 106 equalizes the distortion caused by the propagation path, and the frequency demapping units 107-1 and 107-2 extract the frequency signal of each first communication device.

  The IDFT units 108-1 and 108-2 convert the extracted frequency signals into time signals, the demodulation units 109-1 and 109-2 calculate the LLRs of the code bits, and the decoding units 110-1 and 110-. 2 performs error correction and outputs an a posteriori LLR of the sign bit, an external LLR, and an a posteriori LLR of the information bit. The post-code and external LLR of the code bit are input to the replica generation units 111-1 and 111-2, and the replica generation units 111-1 and 111-2 generate a transmission signal replica using these. The generated transmission signal replicas are input to reception signal replica generation units 112-1 and 112-2, and reception signal replica generation units 112-1 and 112-2 generate reception signal replicas.

  Since reception signal replica generation section 112-1 uses the transmission signal of the first first communication device as a detection target, transmission signal replica generated from the external LLR of the first first communication device and 2 The transmission signal replica generated from the posterior LLR of the second second communication apparatus is input. The reception signal replica generation unit 112-2 is the opposite. Then, reception signal replica generation sections 112-1 and 112-2 input the reception signal replica again to cancellation section 105 and repeat the subsequent processing.

  The cancel unit 105 cancels the received signal replica generated from the external LLR for the signal to be detected, as in the first embodiment. And cancellation part 105 uses the received signal replica generated from posterior LLR about the signal of the 1st communication apparatus other than that (namely, signal used as inter-user interference). With such reception processing, reception performance can be improved.

  It should be noted that the present invention is based on the fact that the post LLR and the external LLR are properly used, and any combination of the methods shown in the first to third embodiments is also included in the present invention.

  The program that operates in the mobile station apparatus and the base station apparatus related to the present invention is a program (a program that causes a computer to function) that controls the CPU and the like so as to realize the functions of the above-described embodiments related to the present invention. Information handled by these devices is temporarily stored in the RAM at the time of processing, then stored in various ROMs and HDDs, read out by the CPU, and corrected and written as necessary.

  As a recording medium for storing the program, a semiconductor medium (for example, ROM, nonvolatile memory card, etc.), an optical recording medium (for example, DVD, MO, MD, CD, BD, etc.), a magnetic recording medium (for example, magnetic tape, Any of a flexible disk etc. may be sufficient. In addition, by executing the loaded program, not only the functions of the above-described embodiment are realized, but also based on the instructions of the program, the processing is performed in cooperation with the operating system or other application programs. The functions of the invention may be realized.

  In the case of distribution in the market, the program can be stored and distributed in a portable recording medium, or transferred to a server computer connected via a network such as the Internet. In this case, the storage device of the server computer is also included in the present invention. Moreover, you may implement | achieve part or all of the mobile station apparatus and base station apparatus in embodiment mentioned above as LSI which is typically an integrated circuit.

  Each functional block of the mobile station apparatus and the base station apparatus may be individually chipped, or a part or all of them may be integrated into a chip. Further, the method of circuit integration is not limited to LSI, and may be realized by a dedicated circuit or a general-purpose processor. In addition, when an integrated circuit technology that replaces LSI appears due to progress in semiconductor technology, an integrated circuit based on the technology can also be used.

  Although the embodiments of the present invention have been described in detail with reference to the drawings, the specific configuration is not limited to these embodiments, and the design and the like within the scope not departing from the gist of the present invention are patented. Included in the claims. The present invention is suitable for use in a mobile communication system in which a mobile phone device is a mobile station device, but is not limited to this.

1 First communication device (transmitting device)
2 Second communication device (receiving device)
11-1, 11-2 Encoding unit 12-1, 12-2 Modulating unit 13 Layer mapping unit 14-1, 14-2 DFT unit 15-1, 15-2 Frequency mapping unit 16-1, 16-2 IFFT unit 17-1, 17-2 Reference signal multiplexers 18-1, 18-2 CP insertion units 19-1, 19-2 Radio unit 21 Radio unit 22 Control signal detectors 31-1, 31-2 Radio unit 32-1 , 32-2 CP removing unit 33-1, 33-2 Reference signal separating unit 34-1, 34-2 FFT unit 35 Canceling unit 36 MIMO separating unit 37-1, 37-2 Frequency demapping unit 38-1, 38 -2 IDFT units 39-1, 39-2 Demodulating units 40-1, 40-2 Decoding units 41-1, 41-2 Replica generation unit 42 Received signal replica generation unit 43 Channel estimation unit 45-1 Decoding processing unit 46 -1 Subtractor 50 Replica Selecting section 51-1, 51-2 replica subtracting unit 61-1 and 61-2 first communication device (transmitting device)
62 Second communication device (receiving device)
71 Code unit 72 Modulation unit 73 DFT unit 74 Frequency mapping unit 75 IFFT unit 76 Reference signal multiplexing unit 77 CP insertion unit 78 Radio unit 79 Radio unit 80 Control information detection unit 91 Curve group 92 showing BLER characteristics of 16QAM 92 Conventional turbo principle A curve 93 showing the BLER characteristic according to the reception method based on the curve 94 showing the reception method of the present application 94 A curve 95 showing the BLER characteristic according to the reception method without repetition processing in the case of 16QAM 95 A curve group 96 showing the BLER characteristic of 64QAM Curve 97 showing BLER characteristic according to reception method based on curve 98 Curve showing BLER characteristic according to reception method of the present invention 98 Curve showing reception method without repetition processing in case of 64QAM 101 Radio unit 102 CP removing unit 103 Reference signal separating unit 104 FFT unit 105 Canceling unit 106 Equalizing unit 1 7-1, 107-2 Frequency demapping unit 108-1, 108-2 IDFT unit 109-1, 109-2 Demodulation unit 110-1, 110-2 Decoding unit 111-1, 111-2 Replica generation unit 112- 1, 112-2 Received signal replica generation unit 113 propagation path estimation unit

Claims (10)

A receiver that receives a plurality of spatially multiplexed signals from a transmitter,
An error correction decoding unit which performs error correction decoding on the received signal and outputs a post-log LLI (Log Likelihood Ratio) of the code bit and an external LLR of the code bit;
A transmission signal replica generation unit that generates a transmission signal replica based on the posterior LLR and the external LLR;
A replica selection unit that selects a combination of transmission signal replicas according to a detection target from the transmission signal replica;
A cancellation unit that removes the received signal replica created based on the combination of the selected transmission signal replicas from the received signal;
A receiving apparatus, comprising: a MIMO separation unit that performs multiple-input multiple-output (MIMO) separation on the signal from which the received signal replica has been removed.   The replica selection unit sets a transmission signal replica to be detected as a transmission signal replica generated from the external LLR, and sets a transmission signal replica other than the detection target as a transmission signal replica generated from the posterior LLR. The receiving apparatus according to claim 1.   The receiving apparatus according to claim 1, wherein a single user MIMO signal is received from the transmitting apparatus.   The receiving apparatus according to claim 1, wherein a multi-user MIMO signal is received from the transmitting apparatus.   The error correction decoding unit is obtained by subtracting the LLR obtained by the demodulation from the a posteriori LLR of the code bit and the a posteriori LLR of the code bit based on the LLR obtained by demodulating the received signal. 2. The receiving apparatus according to claim 1, wherein an external LLR of a code bit to be output is output. A receiving device that receives a plurality of signals overlapped by some subcarriers from a transmitting device,
An equalization unit for equalizing the distortion of the propagation path;
An error correction decoding unit which performs error correction decoding on the received signal and outputs a post-log LLI (Log Likelihood Ratio) of the code bit and an external LLR of the code bit;
A transmission signal replica generation unit that generates a transmission signal replica based on the posterior LLR and the external LLR;
A cancellation unit that removes the received signal replica created based on the combination of the generated transmission signal replicas from the received signal, and
The transmission signal replica generation unit sets a transmission signal replica to be detected as a transmission signal replica generated from the external LLR, and sets a transmission signal replica other than the detection target as a transmission signal replica generated from the posterior LLR. A receiving device. A program for a receiving device that receives a plurality of spatially multiplexed signals from a transmitting device,
A process of performing error correction decoding on the received signal and outputting an a posteriori LLR (Log Likelihood Ratio) of the code bit and an external LLR of the code bit;
Generating a transmission signal replica based on the posterior LLR and the external LLR;
A process of selecting a combination of transmission signal replicas according to a detection target from the transmission signal replicas;
A process of removing a received signal replica created based on the combination of the selected transmitted signal replicas from the received signal;
A program for causing a computer to execute a series of processes of performing MIMO (Multiple-Input Multiple-Output) separation on a signal from which the received signal replica has been removed. A program for a receiving device that receives a plurality of signals duplicated by some subcarriers from a transmitting device,
A process for equalizing the distortion of the propagation path;
A process of performing error correction decoding on the received signal and outputting an a posteriori LLR (Log Likelihood Ratio) of the code bit and an external LLR of the code bit;
Generating a transmission signal replica based on the posterior LLR and the external LLR;
A process of removing a received signal replica created based on a combination of the generated transmission signal replicas from the received signal;
A computer performs a series of processes including a transmission signal replica to be detected as a transmission signal replica generated from the external LLR and a transmission signal replica other than the detection target as a transmission signal replica generated from the posterior LLR. A program characterized by being executed. An integrated circuit that, when mounted on a receiving device, causes the receiving device to perform a plurality of functions,
A function of receiving a plurality of spatially multiplexed signals from a transmission device;
A function of performing error correction decoding on the received signal and outputting an a posteriori LLR (Log Likelihood Ratio) of the sign bit and an external LLR of the sign bit;
A function of generating a transmission signal replica based on the posterior LLR and the external LLR;
A function of selecting a combination of transmission signal replicas according to a detection target from the transmission signal replicas;
A function of removing the received signal replica created based on the combination of the selected transmitted signal replicas from the received signal;
An integrated circuit characterized by causing the receiving apparatus to exhibit a series of functions of performing MIMO (Multiple-Input Multiple-Output) separation on a signal from which the received signal replica has been removed. An integrated circuit that, when mounted on a receiving device, causes the receiving device to perform a plurality of functions,
A function of receiving a plurality of signals duplicated in some subcarriers from a transmission device;
A function to equalize propagation path distortion;
A function of performing error correction decoding on the received signal and outputting an a posteriori LLR (Log Likelihood Ratio) of the sign bit and an external LLR of the sign bit;
A function of generating a transmission signal replica based on the posterior LLR and the external LLR;
A function of removing the received signal replica created based on the combination of the generated transmission signal replicas from the received signal;
The transmission signal replica to be detected is a transmission signal replica generated from the external LLR, and the transmission signal replica other than the detection target is a transmission signal replica generated from the posterior LLR. An integrated circuit characterized by being exhibited by a receiving device.