JP2012060407A - Reception device, communication system, control program of reception device, and integrated circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately estimate an impulse response of a propagation path even when pilot signals are arranged narrowly in contrast with a band width to which FFT is performed.SOLUTION: A reception device 300 estimating an impulse response by using pilot signals arranged in a narrower band width than a band width to which FFT (Fast Fourier Transform) is performed comprises: a reception part 302 receiving the pilot signals and information data allocated by a predetermined resource unit; a propagation path estimation part 304 calculating a propagation path estimation value by using the pilot signals; and signal detection parts 309-1 and 309-2 detecting the information data. The propagation path estimation part 304 estimates the impulse response by using a pilot signal which is transmitted by a transmission device being the same transmission device transmitting an information data signal, and belongs to a resource differing from the resource that the information data signal is allocated to.

Description

  The present invention relates to a technique for estimating an impulse response using a pilot signal arranged in a band narrower than a band for performing FFT (Fast Fourier Transform).

  In wireless communication, multi-carrier transmission schemes such as OFDM (Orthogonal Frequency Division Multiplex) and MC-CDMA (Multi Carrier-Code Division Multiple Access) are multi-carrier and guard interval (GI). The insertion can reduce the influence of frequency selective multipath fading and multipath delay spread in high-speed digital signal transmission. However, in OFDM and the like, when a delayed wave exceeding the guard interval section exists, intersymbol interference (ISI: Inter Symbol Interference) caused by the preceding symbol entering the Fast Fourier Transform (FFT) section or high speed Inter-carrier interference (ICI) occurs when symbol breaks, that is, signal discontinuous sections, enter the Fourier transform section, causing deterioration of characteristics.

  FIG. 23 is a diagram illustrating an outline of a signal that reaches a receiving device from a transmitting device through a multipath environment. In FIG. 23, the horizontal axis represents time. The OFDM symbol is composed of an effective symbol and a guard interval that is arranged in front of the effective symbol and is added by copying the latter half of the effective symbol.

  When the FFT processing is performed in the interval t4 in synchronization with the preceding wave s1 (the first wave that arrives), the delay wave s2 shows an example when the delay time falls within the delay t1 within the guard interval. Delayed waves s3 and s4 are delayed waves with delays t2 and t3 exceeding the guard interval. The preceding wave and the delayed wave are also called incoming waves. The hatched portion in FIG. 23 indicates the component of the OFDM symbol before the desired OFDM symbol.

  As for the delayed waves s3 and s4, as indicated by the hatched portion, the OFDM symbol before the desired OFDM symbol is in the FFT interval t4, and inter-symbol interference (ISI: Inter-Symbol Interference) occurs. Further, in the delayed wave s3, a break between the desired OFDM symbol and the OFDM symbol before the desired OFDM symbol is made in the interval t4, and inter-carrier interference (ICI: Inter-Carrier Interference) occurs. Similarly, in the delayed wave s4, a break is made between the desired OFDM symbol and the OFDM symbol before the desired OFDM symbol in the section t4, and inter-carrier interference occurs.

  One method for improving the characteristic deterioration due to the inter-symbol interference and the inter-carrier interference is proposed in the following Patent Document 1, Patent Document 2, and Non-Patent Document 1. In these techniques, after performing a demodulation operation once in the receiving apparatus, an error correction result (MAP (Maximum A posteriori Probability: maximum posterior probability) decoder output) is used, and the inter-symbol interference component and the inter-carrier interference are used. After creating a replica signal (interference replica signal) of an undesired subcarrier containing components, the signal removed from the received signal is subjected to signal equalization processing based on the MMSE (Minimum Mean Square Error) norm and demodulated again By repeating the process of performing the operation, characteristic deterioration due to intersymbol interference and intercarrier interference is improved. A technique for repeatedly performing interference removal, equalization processing, and decoding processing while exchanging soft decision results is referred to as turbo equalization.

  In the turbo equalization described above, an impulse response of the propagation path is required to generate an interference replica signal. Patent Document 1 discloses an estimation method of an impulse response using a modulation replica obtained from a pilot signal that is a known signal included in a received signal and an expected value of a log likelihood ratio that is a decoding processing result. Specifically, the channel response is estimated by controlling by the least square method so that the absolute value square value of the difference between the received signal and the pilot signal and the modulation replica is minimized.

  FIG. 24 is a diagram illustrating an example in which a data signal and a pilot signal are allocated in OFDMA (Orthogonal Frequency Division Multiple Access). FIG. 24 illustrates CRS (Common Reference Signal) in LTE (Long Term Evolution) described in Non-Patent Document 2. OFDMA is a multiple access that assigns data of a plurality of users to subcarriers that constitute OFDM. The vertical axis is frequency and the horizontal axis is time. Here, a unit composed of one subcarrier and one OFDM symbol is called a resource element, and a unit composed of 12 subcarriers and 14 OFDM symbols is called a resource block. User data signals are allocated in units of resource blocks. In FIG. 24, the filled portion is a resource element for arranging a pilot signal used for propagation path estimation, the hatching portion that rises to the right is a resource element that places the data signal of user 1, and the hatching portion that is obliquely rising to the left is user 2 data Indicates a resource element for placing a signal. The pilot signal is a pilot signal that is distributed in the system band and includes a cell-specific sequence. When the terminal of the user 1 is a receiving apparatus having the above-described turbo equalization, an impulse response is calculated using the pilot signal in channel estimation. Since the pilot signal is cell-specific, the user 2 can similarly perform propagation path estimation.

JP 2004-211702 A WO2007 / 136056

K, Shimzawa, “A Novel SC / MMSE Turbo Evaluation for Multisystem Systems with Insufficiency Cyclic Prefix” IEEE PIMRC2008 “3rd Generation Partnership Project; Technical Specification Group Radio Access Network; E3U.

  However, in the above-described channel estimation in turbo equalization, when the pilot signal is user-specific or when the pilot signal is not dispersed in the system band, the estimation accuracy of the impulse response deteriorates, and as a result, turbo equalization The interference removal performance of the system is reduced.

  FIG. 25 is a diagram showing an example where user-specific pilot signals are arranged in OFDMA. The vertical axis is frequency and the horizontal axis is time. In FIG. 25, the hatched portion that rises diagonally to the right indicates the resource element that arranges the user 1 data signal, and the hatched portion that rises diagonally to the left indicates the resource element that arranges the data signal of user 2. Further, the painted portion is a resource element for placing the pilot signal 1 used by the user 1 for channel estimation, and the shaded portion is a resource element for placing the pilot signal 2 used by the user 2 for channel estimation. Pilot signal 1 and pilot signal 2 are sequences unique to each user. That is, if the user is different, the series is different. Examples of the pilot signal sequence include CAZAC (Constant Amplitude-Zero Auto Correlation).

  Here, the case where the receiving device of the user 1 having the turbo equalization function receives a signal in the format shown in FIG. 24 and the case where the signal is received in the format shown in FIG. 25 are compared. When received in the format of FIG. 24, the impulse response can be estimated using pilot signals distributed over the entire system band (subcarrier indexes 0 to 299). For example, when an impulse response is estimated in the first subframe (OFDM symbol 0 to OFDM symbol 13), a pilot signal distributed over the entire system band in that section can be used. On the other hand, when receiving in the format shown in FIG. 25, only the pilot signal 1 is a known signal, and the user 1 estimates the impulse response using only the pilot signal 1. For example, when the impulse response is estimated in the first subframe, only the pilot signal 1 arranged in the band (subcarrier index 0 to 11) allocated to the user 1 in that section can be used. In this case, the band (subcarrier index 0 to 11) in which pilot signal 1 is arranged is substantially narrower than the system band (subcarrier index 0 to 299) (that is, equivalent to a wider guard band). Therefore, each path constituting the impulse response is expanded.

  FIG. 26 is a diagram illustrating an example of a delay profile of a received signal. In FIG. 26, the horizontal axis represents time and the vertical axis represents power. The power is calculated from the amplitude / phase component of the impulse response. FIG. 26 shows a case where two paths (p1, p2) have arrived. A solid line indicates a case where the receiving apparatus receives a signal transmitted in the format shown in FIG. 24 and calculates an impulse response using a pilot signal (painted portion). However, it is assumed that there is no influence by the scattered arrangement. A broken line indicates a case where the receiving apparatus receives a signal transmitted in the format shown in FIG. 25 and calculates an impulse response using a pilot signal (painted portion). In this case, since the band (subcarrier index 0 to 11) where the pilot signal is arranged is narrower than the FFT band (subcarrier index 0 to 299), each path is widened. As a result, when the range of the two incoming paths is extracted by the filter, a loss of the signal component that spreads outside the filter range occurs, causing a problem of reducing the estimation error of the impulse response.

  The present invention has been made in view of the above-described problem, and is capable of accurately estimating the impulse response of the propagation path even when the pilot signal arrangement is narrower than the band in which the FFT is performed. It is an object to provide a system, a control program for a receiving apparatus, and an integrated circuit.

  (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 estimates an impulse response using a pilot signal arranged in a band narrower than a band for performing FFT (Fast Fourier Transform), and is allocated in units of predetermined resources. A receiver that receives the received information data and pilot signal, a channel estimator that calculates a channel estimation value using the pilot signal, and a signal detector that detects the information data, and the channel estimation A pilot signal transmitted by the same transmission apparatus as the transmission apparatus that transmitted the information data signal, and using a pilot signal belonging to a resource different from the resource to which the information data signal is allocated, The estimation is performed.

  In this way, since the impulse response is estimated using a pilot signal belonging to a resource different from the resource to which the information data signal is assigned, the pilot signal is arranged in a band narrower than the band for performing FFT. However, the accuracy of propagation path estimation can be maintained.

  (2) Also, in the receiving apparatus of the present invention, the propagation path estimation unit estimates the impulse response using a pilot signal belonging to a resource having a frequency band different from that of the resource to which the information data is allocated. It is characterized by.

  Thus, since the impulse response is estimated using a pilot signal belonging to a resource having a frequency band different from that of the resource to which the information data is allocated, the pilot signal is arranged in a band narrower than the band in which FFT is performed. Even in this case, the accuracy of propagation path estimation can be maintained.

  (3) In the reception apparatus of the present invention, the propagation path estimation unit estimates the impulse response using a pilot signal belonging to a resource whose subframe is different from the resource to which the information data signal is allocated. It is characterized by that.

  Thus, since the impulse response is estimated using a pilot signal that belongs to a resource whose subframe is different from the resource to which the information data signal is allocated, the pilot signal is arranged in a band narrower than the band in which FFT is performed. Even in this case, it is possible to maintain the accuracy of propagation path estimation.

  (4) In the reception apparatus of the present invention, the propagation path estimation unit estimates the impulse response using a pilot signal belonging to a resource having a frequency band and subframe different from that of the resource to which the information data is allocated. It is characterized by performing.

  Thus, since the impulse response is estimated using a pilot signal belonging to a resource having a frequency band and subframe different from that of the resource to which the report data is allocated, the pilot signal is in a band narrower than the band in which FFT is performed. Even if it is arranged, it is possible to maintain the accuracy of propagation path estimation.

  (5) In the reception apparatus of the present invention, the reception unit receives information data and a pilot signal allocated in predetermined resource units in initial transmission and retransmission for the initial transmission, and the propagation path estimation unit The impulse response is estimated using pilot signals received by the initial transmission and the retransmission.

  As described above, since the impulse response is estimated using the pilot signal received by the initial transmission and the retransmission, it is possible to expand the band in which the pilot signal is arranged with respect to the bandwidth for performing the FFT during the retransmission. It becomes. As a result, when the impulse response is estimated, it is possible to suppress the arrival path from being widened, and it is possible to improve the propagation path estimation accuracy. When the impulse response estimation accuracy is improved in this way, the reception performance at the time of retransmission is improved. For example, the number of retransmissions of hybrid ARQ can be reduced, and the transmission efficiency can be improved.

  (6) Further, in the receiving device of the present invention, the signal detection unit detects information data in the initial transmission using the estimated impulse response.

  In this way, since the information data in the initial transmission is detected using the estimated impulse response, it is possible to improve the reception performance.

  (7) In the receiving apparatus of the present invention, the signal detection unit detects information data in the retransmission using the estimated impulse response.

  In this way, information data in retransmission is detected using the estimated impulse response, so that it is possible to improve reception performance.

  (8) Further, the receiving apparatus of the present invention further includes a propagation path compensation unit that performs propagation path compensation using the estimated value of the impulse response.

  Thus, since propagation path compensation is performed using the estimated value of the impulse response, it is possible to improve reception performance.

  (9) The receiving apparatus of the present invention is further characterized by further comprising an interference removing unit that performs interference removing processing using the estimated value of the impulse response.

  As described above, since the interference cancellation processing is performed using the estimated value of the impulse response, it is possible to improve the reception performance.

  (10) In the reception apparatus of the present invention, the interference removal unit generates an interference replica using a soft decision result of the information data output from the signal detection unit and an estimated value of the impulse response. A generating unit; and a subtracting unit that subtracts the interference replica from the received signal.

  With this configuration, it is possible to perform turbo equalization in which interference cancellation, equalization processing, and decoding processing are repeatedly performed while exchanging soft decision results, so that a high gain pilot signal is arranged for the bandwidth for performing FFT Bandwidth can be expanded. As a result, when the impulse response is estimated, the arrival path is prevented from spreading, and the propagation path estimation accuracy can be improved.

  (11) Further, the communication system of the present invention includes a transmission device that arranges a pilot signal in a band narrower than a band in which the reception device performs FFT (Fast Fourier Transform), and transmits the signal to the reception device; It is comprised from the receiver of said (1) description, It is characterized by the above-mentioned.

  In this way, since the impulse response is estimated using a pilot signal belonging to a resource different from the resource to which the information data signal is assigned, the pilot signal is arranged in a band narrower than the band for performing FFT. However, the accuracy of propagation path estimation can be maintained.

  (12) In the communication system of the present invention, the transmission device allocates information data and pilot signals in predetermined resource units and transmits the initial transmission and retransmission for the initial transmission to the reception device. In the initial transmission and retransmission for the initial transmission, the reception apparatus receives information data and pilot signals allocated in predetermined resource units, and uses the pilot signals received in the initial transmission and the retransmission to transmit an impulse response The estimation is performed.

  As described above, since the impulse response is estimated using the pilot signal received by the initial transmission and the retransmission, it is possible to expand the band in which the pilot signal is arranged with respect to the bandwidth for performing the FFT during the retransmission. It becomes. As a result, when the impulse response is estimated, it is possible to suppress the arrival path from being widened, and it is possible to improve the propagation path estimation accuracy. When the impulse response estimation accuracy is improved in this way, the reception performance at the time of retransmission is improved. For example, the number of retransmissions of hybrid ARQ can be reduced, and the transmission efficiency can be improved.

  (13) Further, in the communication system according to the present invention, the transmission apparatus allocates the information data resource in the retransmission to a resource having a different frequency band from the resource to which the information data in the initial transmission is allocated. .

  Thus, since the resource of information data in retransmission is allocated to a resource having a frequency band different from that of the resource to which information data in initial transmission is allocated, the pilot signal is used for the bandwidth for performing FFT during retransmission of the receiving apparatus. It is possible to expand the band in which is arranged. As a result, when the impulse response is estimated, it is possible to suppress the arrival path from being widened, and it is possible to improve the propagation path estimation accuracy. When the impulse response estimation accuracy is improved in this way, the reception performance at the time of retransmission is improved. For example, the number of retransmissions of hybrid ARQ can be reduced, and the transmission efficiency can be improved.

  (14) Further, the control program for the receiving apparatus of the present invention is a control program for the receiving apparatus that estimates an impulse response using a pilot signal arranged in a band narrower than a band for performing FFT (Fast Fourier Transform). Processing for receiving information data and pilot signals allocated in predetermined resource units, processing for calculating propagation path estimated values using the pilot signals, processing for detecting the information data, and the information data signal Processing for estimating an impulse response using a pilot signal transmitted by the same transmitting apparatus as the transmitting apparatus that transmitted the signal, and using a pilot signal belonging to a resource different from the resource to which the information data signal is allocated, and A series of processes is commanded to be readable and executable on a computer. The

  In this way, since the impulse response is estimated using a pilot signal belonging to a resource different from the resource to which the information data signal is assigned, the pilot signal is arranged in a band narrower than the band for performing FFT. However, the accuracy of propagation path estimation can be maintained.

  (15) Further, the control program of the receiving apparatus according to the present invention includes a process of receiving information data and a pilot signal allocated in predetermined resource units in initial transmission and retransmission for the initial transmission, and the initial transmission and the retransmission. And a process of estimating an impulse response using the pilot signal received in step (1).

  As described above, since the impulse response is estimated using the pilot signal received by the initial transmission and the retransmission, it is possible to expand the band in which the pilot signal is arranged with respect to the bandwidth for performing the FFT during the retransmission. It becomes. As a result, when the impulse response is estimated, it is possible to suppress the arrival path from being widened, and it is possible to improve the propagation path estimation accuracy. When the impulse response estimation accuracy is improved in this way, the reception performance at the time of retransmission is improved. For example, the number of retransmissions of hybrid ARQ can be reduced, and the transmission efficiency can be improved.

  (16) Further, the integrated circuit of the present invention is an integrated circuit that is mounted on a receiving device, thereby causing the receiving device to exhibit a plurality of functions, and has a narrower band than a band in which FFT (Fast Fourier Transform) is performed. A function of estimating an impulse response using a pilot signal arranged in the base station, a function of receiving information data and a pilot signal allocated in predetermined resource units, and calculating a propagation path estimation value using the pilot signal A pilot signal transmitted by the same transmission apparatus as the transmission apparatus that transmitted the information data signal, and belongs to a resource different from the resource to which the information data signal is allocated. A function of estimating an impulse response using a pilot signal, and causing the receiving apparatus to exhibit the function .

  In this way, since the impulse response is estimated using a pilot signal belonging to a resource different from the resource to which the information data signal is assigned, the pilot signal is arranged in a band narrower than the band for performing FFT. However, the accuracy of propagation path estimation can be maintained.

  (17) The integrated circuit of the present invention has a function of receiving information data and a pilot signal allocated in a predetermined resource unit in initial transmission and retransmission for the initial transmission, and received by the initial transmission and the retransmission. And a function of estimating an impulse response using the pilot signal.

  As described above, since the impulse response is estimated using the pilot signal received by the initial transmission and the retransmission, it is possible to expand the band in which the pilot signal is arranged with respect to the bandwidth for performing the FFT during the retransmission. It becomes. As a result, when the impulse response is estimated, it is possible to suppress the arrival path from being widened, and it is possible to improve the propagation path estimation accuracy. When the impulse response estimation accuracy is improved in this way, the reception performance at the time of retransmission is improved. For example, the number of retransmissions of hybrid ARQ can be reduced, and the transmission efficiency can be improved.

  According to the present invention, it is possible to accurately estimate the propagation path when the pilot signal arrangement is narrower than the FFT band.

It is a figure which shows an example of the communication system in embodiment of this invention. It is a figure which shows the frame format in the uplink r2 and r4. It is a block diagram which shows the example of 1 structure of the mobile station apparatus 100 which concerns on the 1st Embodiment of this invention. It is a block diagram which shows one structural example of the base station apparatus 300 which concerns on the 1st Embodiment of this invention. 3 is a block diagram illustrating a configuration example of a propagation path estimation unit 304. FIG. It is a flowchart which shows the procedure of propagation path estimation. 3 is a block diagram illustrating an exemplary configuration of an interference removal unit 305. FIG. 4 is a block diagram illustrating a configuration example of a replica generation unit 342. FIG. 4 is a flowchart showing an operation of the base station apparatus 300. It is a figure which shows the frame format in the uplink r2 and r4 in the communication system which concerns on the 2nd Embodiment of this invention. It is a figure which shows the relationship of the system band, FFT band, and pilot signal band in this invention. It is a block diagram which shows the example of 1 structure of the mobile station apparatus 100 which concerns on the 3rd Embodiment of this invention. It is a figure which shows an example of a precoding matrix. It is a block diagram which shows the example of 1 structure of the encoding part 111 which concerns on the 4th Embodiment of this invention. It is a figure which shows the internal structure of the error correction encoding part 603 at the time of applying a turbo code as an encoding system at the time of the error correction encoding part 603 performing error correction encoding by the encoding rate R = 1/3. . It is a figure which shows the example of the said predetermined pattern group which the puncture part 607 hold | maintains. It is a block diagram which shows the example of 1 structure of the base station apparatus 300 which concerns on the 4th Embodiment of this invention. It is a figure which shows schematic structure of the propagation path estimation part 304 in 4th Embodiment. It is a figure which shows an example of the sequence of the communication system which performs hybrid automatic repeat request | requirement HARQ between the mobile station apparatus 100 and the base station apparatus 700. FIG. It is a figure which shows an example of allocation of a data signal, a pilot signal, and a control signal in an initial transmission signal. It is a figure which shows an example of allocation of a data signal, a pilot signal, and a control signal in a retransmission signal. It is a figure which shows the pilot signal arrangement | positioning used for impulse response estimation at the time of performing an interference removal process, a demodulation process, a decoding process, etc. in step S307. It is a figure which shows the outline | summary of the signal which reaches | attains a receiver from a transmitter via a multipath environment. It is a figure which shows the example at the time of assigning a data signal and a pilot signal in OFDMA (Orthogonal Frequency Division Multiple Access). It is a figure which shows the example by which a user specific pilot signal is arrange | positioned in OFDMA. It is a figure which shows an example of the delay profile of a received signal.

(First embodiment)
FIG. 1 is a diagram illustrating an example of a communication system according to an embodiment of the present invention. In the communication system of the present invention, a plurality of mobile station apparatuses are connected to the base station apparatus. In FIG. 1, mobile station apparatus 100-1 and mobile station apparatus 100-2 (mobile station apparatus 100-1 and mobile station apparatus 100-2 are collectively referred to as mobile station apparatus 100) are connected to base station apparatus 300. This is the case. r1 is the downlink in the connection between the base station apparatus 300 and the mobile station apparatus 100-1, r2 is the uplink in the connection between the base station apparatus 300 and the mobile station apparatus 100-1, and r3 is the base station apparatus 300 and the mobile station apparatus. The downlink in the connection with 100-2, r4 is the uplink in the connection between the base station apparatus 300 and the mobile station apparatus 100-2. For example, r1 and r3 correspond to a downlink common channel (PDSCH), a downlink control channel (PDCCH), a synchronization channel (SCH), and the like in LTE. r2 and r4 correspond to, for example, an uplink common channel (PUSCH), an uplink control channel (PUCCH), a random access channel (RACH), and the like in LTE.

  FIG. 2 is a diagram illustrating a frame format in the uplinks r2 and r4. The horizontal axis is time, and the vertical axis is frequency. In FIG. 2, the frequency bands at both ends of the system band are allocated to uplink control channels (subcarrier indexes 0 to 23 and 276 to 299). In the uplink control channel, control data such as a response signal, CQI (Channel Quality Indicator), and RI (Rank Indicator) is transmitted. The response signal is a signal notifying whether or not the data signal transmitted from the base station apparatus 300 on the downlink has been correctly received. The CQI is a signal used by the mobile station apparatus 100 to notify an MCS (Modulation and Channel coding Scheme) that satisfies Qos on the uplink common channel. The RI is a signal used by the mobile station apparatus 100 to notify the number of spatial multiplexing satisfying Qos on the uplink common channel.

  In the uplink common channel, information data transmitted from each mobile station apparatus 100 to the base station apparatus 300 is transmitted. In FIG. 2, hatching portions (subcarrier indexes 24 to 47 of subframe # 1) that are diagonally upward to the right are resource elements that allocate information data that mobile station apparatus 100-1 transmits to base station apparatus 300. The painted portion is a resource element (for example, DMRS (Demodulation Reference Signal)) in which the pilot signal 1 used for propagation path estimation is arranged.

  The hatched portions (subcarrier indexes 24 to 47 and 264 to 275 of subframe # 2) that are diagonally upward to the left are resource elements that allocate information data that the mobile station device 100-2 transmits to the base station device 300. The shaded part is a resource element (for example, DMRS (Demodulation Reference Signal)) in which the pilot signal 2 used for propagation path estimation is arranged.

  Note that the scheduling of resource elements to which the information data and the pilot signal are allocated is set by the base station apparatus 300 based on CQI and the like transmitted from each mobile station apparatus 100 to the base station apparatus 300. The resource element to which the information data and the like of each mobile station device 100 is allocated is notified by the downlink control information channel.

  FIG. 3 is a block diagram showing a configuration example of the mobile station apparatus 100-1 according to the first embodiment of the present invention. In the present embodiment, a case where DFT (Discrete Fourier Transform) -Spread-OFDM is applied as an uplink transmission method will be described, but the present invention is not limited thereto. For example, OFDM transmission may be used.

  The mobile station device 100-1 includes an upper layer 102, a symbol generation unit 103, a resource mapping unit 105-m (the resource mapping units 105-1 to 105-m are collectively referred to as a resource mapping unit 105), IFFT (inverse fast Fourier transform). (Conversion) unit 106-m, GI insertion unit 107-m, transmission unit 108-m, pilot symbol generation unit 109, and control symbol generation unit 110. The transmission unit 108-m includes a transmission antenna unit 101-m ( The transmission antenna units 101-1 to 101-m are collectively referred to as the transmission antenna unit 101). In addition, the mobile station device 100-1 includes a reception unit 122 and a control signal detection unit 123, and a reception antenna unit 121 is connected to the reception unit 122. Here, m is the number of transmission antennas. FIG. 3 shows a case where m = 1.

  Note that, when a part or all of the mobile station device 100-1 is formed into a chip to form an integrated circuit, a chip control circuit (not shown in the figure) that controls each functional block is provided.

  The symbol generation unit 103 generates a spectrum of a data modulation symbol from information data input from an upper layer 102 (a layer having a function located in an upper layer such as a MAC layer (Media Access Control) or a network layer). To do.

  The symbol generation unit 103 includes a coding unit 111, an interleaving unit 112, a modulation unit 113, and a DFT unit 114. The encoding unit 111 performs error detection encoding for information detection on the reception side such as CRC (Cyclic Redundancy Check) for information data. The encoding unit 111 performs any error correction encoding process such as a turbo code, LDPC (Low Density Parity Check), or a convolutional code on the information data subjected to error detection encoding. The information data subjected to the error correction coding process is called a coded bit.

  The function for error detection coding may be performed by the upper layer 102. In that case, information data subjected to error detection coding is input to the coding unit 111.

  Interleaving section 112 changes the order of the encoded bits output from encoding section 111 in order to improve the occurrence of a burst error due to a drop in received power due to frequency selective fading. The modulation unit 113 maps the coded bits output from the interleaving unit 112, and includes BPSK (Binary Phase Shift Keying), QPSK (Quadrature Phase Shift Keying), and 16QAM (Quadrature Phase Shift Keying). Data modulation symbols such as 16 Quadrature Amplitude Modulation (16-value quadrature amplitude modulation) and 64QAM (64 Quadrature Amplitude Modulation) are generated.

  The DFT unit 114 generates a spectrum of the data modulation symbol by performing DFT processing on the data modulation symbol.

  Pilot symbol generation section 109 generates a pilot symbol that allows base station apparatus 300 to estimate the propagation path. The pilot symbol is generated in a unique sequence for each mobile station apparatus 100 based on a command from the upper layer 102. The code sequence constituting the pilot symbol is preferably an orthogonal sequence such as a Hadamard code or a CAZAC (Constant Amplitude Zero Auto-Correlation) sequence.

  The control symbol generation unit 110 performs error correction coding and modulation mapping on the uplink control channel (various control data such as response signal, CQI, and RI) output from the higher layer 102, and generates a control symbol.

  The resource mapping unit 105-m maps the spectrum of the data modulation symbol, the pilot symbol, and the control symbol to subcarriers based on the signal allocation information notified from the data upper layer 102 (hereinafter referred to as scheduling). . The signal allocation information is information indicating resource elements to which the spectrum of the data modulation symbol, the pilot symbol, and the control symbol are allocated. For example, it is information indicating the arrangement of each symbol based on the frame format of FIG. A resource element is a unit composed of one subcarrier and one SC-FDM symbol. In FIG. 3, m resource mapping units 105 are provided and scheduling is performed for each transmission antenna 101. However, one resource mapping unit 105 may perform scheduling for all transmission antennas 101 at once.

  The IFFT unit 106-m performs IFFT processing on the signal output from the resource mapping unit 105-m, thereby converting each symbol from a frequency domain signal to a time domain signal.

Next, the GI insertion unit 107-m adds a guard interval (GI) to the time-domain signal converted by the IFFT unit 106-m. For example, a part of the latter half of the time domain signal (effective symbol) output from the IFFT unit 106-m is copied and added to the head of the effective symbol. The effective symbol with the GI added is called an SC-FDM symbol. When a signal output from the GI insertion unit 107-m is a vector s _i , it can be expressed by the following equation (1). The vector s _i is an SC-FDM signal of the i-th symbol _{, where} C _{i, k} is the modulation signal of the i-th symbol k-th subcarrier.

ただし，Ｔは転置を表す．また，Ｆ_ＩはＧＩ挿入を含んだＮ_ｓ×Ｎ_ｆのＩＦＦＴ行列であり、Ｍは信号割当情報に基づくマッピング行列であり、Ｎ_ｃはＧＩポイント数である。（Ｆ_Ｉ）_ｐ，ｑはＦ_Ｉのp行q列要素を表す。また、Ｎ_ｓはＮ＋Ｎ_ｃである。

T represents transposition. Further, _{F I} is the IFFT matrix containing GI insertion _{N s} × _{N f,} M is a mapping matrix based on signal allocation information, _{N c} is the GI points. (F _I ) _{p and q} represent p rows and q columns elements of F _I. N _s is N + N _c .

  Transmitting section 108-m converts the SC-FDM symbol output from GI insertion section 107-m into an analog signal (Digital to Analog conversion), and performs a filtering process to limit the band of the signal converted into the analog signal Then, the filtered signal is up-converted to a transmittable frequency band and transmitted through the transmission antenna unit 101-m. A signal output from the transmission apparatus 100 is referred to as an SC-FDMA signal. Moreover, the mobile station apparatus 100-1 has a function of receiving a signal transmitted from the base station apparatus 300.

  The mobile station device 100-1 receives the control signal transmitted from the base station device 300 via the reception antenna unit 121, and the reception unit 122 can perform digital signal processing such as signal detection processing on the control signal and the like. A down-conversion to a frequency band and a filtering process to remove spurious are performed, and the filtered signal is converted from an analog signal to a digital signal (Analog to Digital conversion).

  The control signal detection unit 123 performs demodulation processing, decoding processing, and the like on the control signal output from the reception unit 122, and includes a downlink common channel (PDSCH), a downlink control channel (PDCCH), a synchronization channel (SCH), and the like. Is detected. Then, the upper layer 102 transmits parameters (MCS, spatial multiplexing number, pilot signal sequence) of uplink data signals to be transmitted to each base station device 300 included in any of the channels input from the control signal detection unit 123. , Frequency allocation, etc.). Then, based on the parameters, a data signal, a pilot signal, a control signal, and the like are output to the symbol generator 103, the pilot symbol generator 109, and the control symbol generator 110.

  The upper layer 102 notifies parameters necessary for each part of the mobile station device 100-1 to perform its function. Note that the mobile station apparatus 100-2 in FIG. 1 has the same configuration as that in FIG.

  FIG. 4 is a block diagram showing a configuration example of the base station apparatus 300 according to the first embodiment of the present invention. The base station apparatus 300 includes a reception unit 302, a reception signal storage unit 303, a propagation path estimation unit 304, an interference removal unit 305, a GI removal unit 306, an FFT unit 307, a propagation path compensation unit 308, and a signal detection unit 309-n (n = 1, 2,..., N, N are provided with the number of mobile station apparatuses (number of users) connected to the base station apparatus 300, and the receiving antenna section 301 is connected to the receiving section 302. The base station apparatus 300 includes a control signal generation unit 312 and a transmission unit 313, and a transmission antenna unit 311 is connected to the transmission unit 313. FIG. 4 shows a case where N = 2. In addition, when the base station apparatus 300 receives signals transmitted from the m multiple antennas by the mobile station apparatus 100-1 or the mobile station apparatus 100-2, the functions of the reception antenna 301 to the upper layer 310 are m transmission signals. (FIG. 4 shows a case where m = 1).

  Further, when a part or all of the base station apparatus 300 is formed into a chip to form an integrated circuit, a chip control circuit (not shown) for controlling each functional block is provided. Hereinafter, a case will be described where mobile station apparatus 100-1 and mobile station apparatus 100-2 are connected to base station apparatus 300 shown in FIG.

  In base station apparatus 300, control signal generation section 312 performs various control data such as MCS, rank information, and scheduling (resource block allocation) of data signals transmitted from mobile station apparatuses 100-1 and 100-2 to base station apparatus 300. Are subjected to error correction coding and modulation mapping to generate control symbols.

  The transmission unit 313 up-converts a signal including the control signal output from the control signal generation unit 312 to a frequency band that can be transmitted in the downlink.

  In base station apparatus 300, when receiving section 302 receives signals from mobile station apparatus 100-1 and mobile station apparatus 100-2 via receiving antenna section 301, the frequency at which digital signal processing such as signal detection processing can be performed. The signal is down-converted to a band, and filtering processing is performed to remove spurious signals. The filtered signal is converted from an analog signal to a digital signal (Analog to Digital conversion), and the received signal storage unit 303, interference canceling unit 305, and propagation Output to the path estimation unit 304. The mobile station device 100-1 and the mobile station device 100-2 are transmitting SC-FDM signals according to the format of FIG.

The reception signal storage unit 303 stores a signal output from the reception unit 302. In addition, in the interference removal processing of the interference removal unit 305, when the repeated processing is performed, this stored signal is output.
When the signal vector in the i-th symbol received by the base station apparatus 300 is r _i , Equation (2) is obtained.

ただし、ｈ_ｉは伝搬路インパルス応答の畳み込み行列、ｎ_ｉは雑音である。

Here, h _i is a convolution matrix of the propagation path impulse response, and n _i is noise.

  The propagation path estimation unit 304 detects fluctuations in amplitude and phase due to fading between the base station apparatus (reception apparatus) 300 and the mobile station apparatus (transmission apparatus) 100-1 or the mobile station apparatus (transmission apparatus) 100-2. The estimated channel is estimated, and the channel estimation value, which is the channel estimation result, is output to the interference removal unit 305 and the channel compensation unit 308. Propagation path estimation unit 304 estimates a propagation path estimated value between mobile station apparatus 100-1 and base station apparatus 300, and is assigned to pilot symbols assigned to resource blocks in which data of mobile station apparatus 100-1 is arranged. To do. Further, the propagation path estimation unit 304 has assigned the estimation of the propagation path estimated value between the mobile station apparatus 100-2 and the base station apparatus 300 to the resource block in which the data of the mobile station apparatus 100-2 is arranged. This is done using pilot symbols. That is, pilot signal 1 is used for propagation path estimation for mobile station apparatus 100-1, and pilot signal 2 is used for propagation path estimation for mobile station apparatus 100-2.

  FIG. 5 is a block diagram illustrating a configuration example of the propagation path estimation unit 304. The propagation path estimation unit 304 includes an FFT unit 331, a pilot signal extraction unit 332, a pilot frequency response calculation unit 333, an impulse response estimation unit 334, and a data frequency response estimation unit 335.

  The FFT unit 331 performs FFT processing on the down-converted SC-FDM signal input from the receiving unit 302 to convert the time domain signal into the frequency domain. The pilot signal extraction unit 332 extracts a predetermined pilot signal for each mobile station apparatus 100 from the frequency domain signal. When performing propagation path estimation for mobile station apparatus 100-1, pilot signal 1 is extracted. That is, in FIG. 2, in order to detect the data signal of mobile station apparatus 100-1 arranged in subframe # 1, it is arranged in subcarrier indexes 24-47 of the third SC-FDM symbol in subframe # 1. Pilot signals arranged in subcarrier indices 24-47 of the tenth SC-FDM symbol of subframe # 1, or both pilot signals are extracted. That is, a pilot signal transmitted by mobile station apparatus 100-1 arranged in a plurality of resource blocks in the same subframe is extracted.

Next, pilot frequency response calculation section 333 calculates the frequency response of the subcarrier in which the pilot signal is arranged, using the extracted pilot signal and the corresponding pilot signal held by base station apparatus 300. Assuming that the extracted pilot signal is Rp _{k, i} , the frequency response estimation value H ^ _{k, i} of the k-th subcarrier of the iSC-FDM symbol is given by Equation (3). Here, the kth subcarrier of the iSC-FDM symbol is a resource block in which the pilot signal is arranged. That is, in the case of the frequency response to the mobile station apparatus 100-1 in FIG. 2, i = 3, 10 and k = 24 to 47 in subframe # 1.

なお、ＳＰ_ｋ，ｉは第ｉＳＣ−ＦＤＭシンボルの第ｋサブキャリアに配置されたパイロット信号、Ｈ_ｋ，ｉは第ｉＳＣ−ＦＤＭシンボルの第ｋサブキャリアの基地局装置３００と移動局装置１００−１間の伝搬路の周波数応答、Ｉ_ｋ，ｉは第ｉＳＣ−ＦＤＭシンボルの第ｋサブキャリアに発生する干渉（ＩＳＩ、ＩＣＩ）である。

SP _{k, i} is a pilot signal arranged in the kth subcarrier of the iSC-FDM symbol, and Hk _{, i} is the base station apparatus 300 and mobile station apparatus 100- of the kth subcarrier of the iSC-FDM symbol. 1, I _{k, i} is the interference (ISI, ICI) generated on the k-th subcarrier of the iSC-FDM symbol.

  Here, the pilot signal arranged in subcarrier indexes 24-47 of the third SC-FDM symbol of subframe # 1 and the subcarrier indexes 24-47 of tenth SC-FDM symbol of subframe # 1 When both pilot signals of the pilot signal are extracted, the frequency responses of the same subcarrier index are weighted and synthesized (equal weighting synthesis is an average). This makes it possible to improve the SNR in calculating the frequency response at the subcarrier index.

  Next, the impulse response estimation unit 334 estimates an impulse response using the frequency response estimation value. An example of the estimation method is shown below.

First, IFFT is performed on the extracted frequency response H ^ _{k, i} . When the signal after IFFT of the extracted frequency response H ^ _{k, i} is a vector h ^ _i , it can be expressed by Expression (4).

ここで、Ｎ_ｐはパイロット信号数、Ｍ_ｐはパイロット信号のマッピング行列である。図２における移動局装置１００−１の場合、Ｍ_ｐは、サブフレーム＃１の第３番のＳＣ−ＦＤＭシンボルのサブキャリアインデックス２４〜４７に配置したパイロット信号あるいはサブフレーム＃１の第１０番のＳＣ−ＦＤＭシンボルのサブキャリアインデックス２４〜４７に配置したパイロット信号、またはその両方のパイロット信号配置に基づくものである。

Here, N _p is the number of pilot signals, and M _p is a pilot signal mapping matrix. In the case of mobile station apparatus 100-1 in FIG. 2, M _p is the pilot signal arranged in subcarrier indexes 24-47 of the third SC-FDM symbol in subframe # 1 or the tenth in subframe # 1. This is based on the pilot signal arrangement at subcarrier indexes 24 to 47 of the SC-FDM symbols of FIG.

Then, in the vector h _i , the phase and amplitude of the section in which it is estimated that the path has arrived, or the phase and amplitude of the discrete point in which it is estimated that the path has arrived, are extracted. Input to the frequency response estimation unit 335. Here, the extracted phase and amplitude are referred to as impulse response estimation values.

  Similarly, it is possible to estimate impulse responses for other mobile station devices 100. When impulse response estimation is performed for mobile station apparatus 100-2 in FIG. 2, pilot signal extraction section 332 performs subcarrier index 24 to 47 and subcarrier index 264 of the third SC-FDM symbol of subframe # 2. Pilot signals arranged at ˜275 and / or pilot signals arranged at subcarrier indexes 24 to 47 and subcarrier indexes 264 to 275 of the tenth SC-FDM symbol of subframe # 2, or both pilot signals (pilot signal 2 ). That is, a pilot signal transmitted by mobile station apparatus 100-2 arranged in a plurality of scattered resource blocks in the same subframe is extracted. Then, using the extracted pilot signal, the above-described pilot frequency response calculation and impulse response estimation are performed.

  Next, the data frequency response estimation unit 335 calculates a frequency response of subcarriers in which data is arranged from the impulse response estimation value. For example, calculation is performed by performing FFT on the estimated impulse response value (referred to as FFT interpolation). The frequency response is input to the propagation path compensation unit 308.

  FIG. 6 is a flowchart showing a procedure of channel estimation. When the base station apparatus 300 receives a signal from the connected mobile station apparatus 100, the base station apparatus 300 performs FFT processing on the signal to convert the time domain signal into the frequency domain (step S101). Next, a pilot signal transmitted by the mobile station apparatus 100 and extracted in the same subframe is extracted from the frequency domain signals (step S102). Then, the frequency response of the subcarrier in which the pilot signal and the known pilot signal possessed are arranged is calculated (step S103).

  Next, the impulse response is estimated by performing IFFT only on the frequency response for the subcarrier in which the pilot signal is arranged (step S104). The impal response estimation is calculated for each mobile station apparatus 100 to which the base station apparatus 300 is connected. In step S104, other known signals may be used in addition to the pilot signal.

  The impulse response estimated value is input to the interference removal unit 305. The impulse response estimated value is calculated by performing FFT processing after extracting a section or discrete point estimated that a path has arrived by using a filter or the like (step S105). Then, the calculated data frequency response is input to the propagation path compensation unit 308, and the flow ends.

  As described above, when data signals are arranged in a plurality of resource blocks, a band in which the pilot signals are arranged with respect to the IFFT bandwidth by using the pilot signals arranged over the plurality of resource blocks. Can be prevented from becoming significantly narrow. As a result, when the impulse response is estimated, it is possible to suppress the spread of the arrival path, and it is possible to improve the estimation accuracy of the impulse response. In addition, the detection accuracy of the path position of the incoming path that constitutes the impulse response can be improved.

  Moreover, since the accuracy of FFT interpolation can be increased by using pilot signals over a plurality of resource blocks, it is possible to accurately calculate the frequency response of subcarriers in which no pilot signals are arranged.

  Returning to FIG. 4, the interference cancellation unit 305 uses the impulse response estimation value output from the propagation path estimation unit 304 and the decoding result output from the signal detection unit 309-n to receive the reception unit 302 or the reception signal storage unit 303. The process of removing the interference component from the signal output from is repeatedly performed. Specifically, using the log likelihood ratio LLR (Log Likelihood Ratio) of the encoded bits after decoding output from the signal detection unit 309-1, the mobile station apparatus 100-1 that is the transmission source of the received signal, and The mobile station device 100-2 generates a signal replica that would have been transmitted to the base station device 300. That is, base station apparatus 300 generates transmission signal replicas for the transmission signals of mobile station apparatus 100-1 and mobile station apparatus 100-2. Further, an interference replica for mobile station apparatus 100-1 and mobile station apparatus 100-2 is generated using this transmission signal replica and an impulse response estimated value from propagation path estimating section 304, and receiving section 302 or received signal storage section 303 is generated. Is subtracted from the signal output from (details will be described later).

  GI removal section 306 removes the guard interval section added by mobile station apparatus 100 in order to avoid distortion due to delayed waves from the signal from which the interference component replica is output from interference removal section 305. The FFT unit 307 performs a Fourier transform process in which the signal from which the GI removal unit 306 has removed the guard interval section is converted from a time domain signal to a frequency domain signal. The propagation path compensation unit 308 calculates a weighting factor for correcting propagation path distortion due to fading using ZF (Zero Forcing), MMSE (Minimum Mean Square Error), and the like, using the frequency response estimation value estimated by the propagation path estimation unit 304. Then, the weighting coefficient is multiplied by the frequency domain signal from the FFT unit 307 to perform propagation path compensation. This process is also called an equalization process. When base station apparatus 300 receives a signal transmitted from m transmission antennas 101 by mobile station apparatus 100, propagation path compensation section 308 also has a function of separating the spatially multiplexed signals.

  Next, the signal detection unit 309-n extracts the subcarrier signal to which the data signal of the desired mobile station apparatus 100 is mapped from the signals output from the propagation path compensation unit 308, and performs demodulation and decoding processing. And get information bits. Also, the encoded bit LLR for the information bit is output to the interference canceller 305. In FIG. 4, a signal detection unit 309-1 and a signal detection unit 309-2 each detect a data signal transmitted by the mobile station device 100-1 and a data signal transmitted by the mobile station device 100-2. Hereinafter, the signal detection unit 309-1 will be described as a representative.

  The signal detection unit 309-1 includes an IDFT unit 320-1, a demodulation unit 321-1, a deinterleave unit 322-1, and a decoding unit 323-1. The IDFT unit 320-1 extracts the equalized signal of the resource element to which the data modulation symbol of the mobile station device 100 is mapped from the signal (the equalized signal) output from the propagation path compensation unit 308, and extracts the signal By performing IDFT processing on the equalized signal, the signal is converted from a frequency domain to a time domain signal. Demodulation section 321-1 performs demodulation processing on the signal output from IDFT section 320-1, and outputs a soft decision value (encoded bit LLR). Specifically, in the case of data modulation symbol allocation shown in FIG. 2, resource elements (K1, L1), (K1 = 24,..., 47, L1 = 0,. However, the demodulating process is performed on the signal obtained by converting the equalized signal (discrete spectrum) corresponding to the time domain into the time domain.

  The processing of demodulating section 321-1 will be described by taking as an example the case where the data modulation symbol transmitted by mobile station apparatus 100 is QPSK modulation. It is assumed that a QPSK symbol transmitted on the transmission side is X and a symbol input to the demodulation unit 321-1 on the reception side is Xc. Assuming that bits constituting X are b0 and b1 (b0, b1 = ± 1), X can be expressed by the following equation (5). However, j represents an imaginary unit. Then, λ (b0) and λ (b1), which are log likelihood ratio LLRs of bits b0 and b1, are obtained from the estimated value Xc on the receiving side of X by the following equation (6).

但し、Ｒｅ（Ｘ_ｃ）は複素数の実部を表す。μは伝搬路補償後の等価振幅であり、例えば、第１のＳＣ−ＦＤＭシンボルの第ｋサブキャリアにおける伝搬路推定値をＨ１（ｋ）、乗算したＭＭＳＥ基準の伝搬路補償重みをＷ１（ｋ）とすると、μはＷ１（ｋ）・Ｈ１（ｋ）となる。

However, Re ( _Xc ) represents the real part of a complex number. μ is the equivalent amplitude after propagation path compensation. For example, H1 (k) is the propagation path estimation value in the k-th subcarrier of the first SC-FDM symbol, and W1 (k ), Μ becomes W1 (k) · H1 (k).

Λ (b1) is obtained by replacing the real part and the imaginary part of _{Xc in} the expression (6), that is, the expression for obtaining λ (b0). It should be noted that it is possible to calculate based on the same principle for data subjected to other modulation such as 16QAM. Further, the demodulator 321-1 may calculate a hard decision result instead of a soft decision result.

  The deinterleaving unit 322-1 performs the rearrangement of the bit arrangement corresponding to the interleaving pattern performed by the interleaving unit 112 of the mobile station device 100, that is, the bit arrangement rearrangement that is the reverse operation of the interleaving pattern. 1 for the data series of soft decision results.

  The decoding unit 323-1 performs error correction decoding processing on the error correction coding such as turbo coding and convolutional coding performed by the mobile station apparatus 100 on the output signal from the deinterleaving unit 322-1 and performs coding. A soft decision output result such as a bit LLR (log likelihood ratio) is calculated and input to the interference removal unit 305 and the upper layer 310. The upper layer 310 performs hard decision, error detection processing, and the like from the soft decision output, and obtains data from each mobile station device 100.

  FIG. 7 is a block diagram illustrating a configuration example of the interference removal unit 305. The interference removal unit 305 includes a subtraction unit 341 and a replica generation unit 342. FIG. 7 shows a case where signals are received from mobile station apparatus 100-1 and mobile station apparatus 100-2. The impulse response estimation value is generated by the propagation path estimation unit 304.

  The replica generation unit 342 generates an interference component replica (interference replica) using the impulse response estimated value and the soft decision value (log likelihood ratio LLR of coded bits) for the data signal of each mobile station apparatus 100. When the base station apparatus 300 receives a signal in the frame shown in FIG. 2, the replica generation unit 342 receives the soft decision result for the data signal of the mobile station apparatus 100-1 and the propagation path estimation unit 304 in subframe # 1. An interference replica is generated using the calculated impulse response estimation value for mobile station apparatus 100. In subframe # 2, an interference replica is generated using the soft decision result for the data signal of mobile station apparatus 100-2 and the impulse response estimation value for mobile station apparatus 100-2 calculated by propagation path estimation section 304. To do. The interference replica may be generated from a hard decision result with respect to the soft decision result.

  The subtracting unit 341 subtracts the interference replica from the signal input from the receiving unit 302 or the received signal storage unit 303.

  Assuming that the signal vector r input from the reception unit 302 or the reception signal storage unit 303 and the vector of the interference replica in the u-th repetitive processing are ri ^ u, the signal vectors ri to u output from the subtraction unit are expressed by Equation (7). It can be expressed as The notations “r ^” and “r˜” mean those in which “^” and “˜” are written on the letter “r” as shown in the equation (7). The same applies to “s ^”, “c ^”, and “h ^” described later.

ただし、初回処理（ｕ＝０）の場合は、ｒ〜ｉ、ｕ＝０である。

However, in the case of initial processing (u = 0), r to i and u = 0.

  FIG. 8 is a block diagram illustrating a configuration example of the replica generation unit 342. The replica generation unit 342 includes an interleaving unit 351-n, a symbol replica generation unit 352-n, a DFT unit 353-n, an IFFT unit 354-n, a GI insertion unit 355-n (n = 1, 2,... N, N is the number of mobile station apparatuses), and an interference replica generation unit 356 is provided. FIG. 8 shows a case where N = 2. First, the replica generation unit 342 uses the log likelihood ratio LLR of the encoded bits after decoding output from the signal detection unit 309-n to cause each mobile station device 100 that is the transmission source of the received signal to Generate a signal replica that would have been sent to. That is, base station apparatus 300 generates transmission signal replicas for signals that mobile station apparatus 100-1 and mobile station apparatus 100-2 would transmit.

  Hereinafter, as a representative example, a case where a transmission signal interference replica for a data signal of mobile station apparatus 100-1 is generated will be described.

  Interleaving section 351-1 arranges the log likelihood ratio LLR of the encoded bits after decoding output from signal detection section 309-1 in the same sequence as the encoded data signal subjected to data modulation by mobile station apparatus 100-1. Sort in order. That is, the log likelihood ratio LLR of the coded bits output from the signal detection unit 309-1 is interleaved with the same interleaving pattern as the interleaving unit 112 of the mobile station device 100-1. That is, the reverse sorting is performed in the reverse direction of the deinterleaving unit 322-1 included in the signal detection unit 309-1.

  The symbol replica generation unit 352-1 generates a data modulation symbol replica (modulation symbol replica) for the signal of the desired user using the log likelihood ratio LLR of the coded bits output from the interleaving unit 351-1. For example, when the modulation scheme of the modulation unit 113 of the mobile station apparatus 100-1 is QPSK modulation, the symbol replica generation unit 352-1 sets the log likelihood ratio of bits b0 and b1 constituting the QPSK modulation symbol to λ (b0) , Λ (b1), a replica symbol of a QPSK modulation symbol represented by the following equation (8) is generated. Note that the symbol replica generation unit 352-1 generates a modulation symbol replica based on the same principle in the case of other modulation such as 16QAM.

ＤＦＴ部３５３−１は、変調シンボルレプリカに対してＤＦＴ処理を行ない、離散スペクトルレプリカを生成する。

The DFT unit 353-1 performs DFT processing on the modulation symbol replica to generate a discrete spectrum replica.

  IFFT section 354-1 corresponds to the resource element to which the discrete spectrum (discrete spectrum of mobile station apparatus 100-1) corresponding to the discrete spectrum replica is assigned in the received SC-FDM signal. The discrete spectrum replica of the mobile station apparatus 100-1 is converted from a frequency domain signal to a time domain signal by mapping to an IFFT input point and performing IFFT processing. Moreover, it is preferable that IFFT section 354-1 arranges the pilot symbol at an IFFT input point corresponding to a resource element in which a pilot symbol which is a known signal has been arranged.

  When the received SC-FDM signal has the frame format of FIG. 2, the discrete spectrum replica output by the DFT unit 353-1 is the resource elements (K1, L1), (K1 = 24... 47, L1) of the subframe # 1. = 0 ... 13, except for resource elements in which pilot symbols are arranged).

The GI insertion unit 355-1 adds a guard interval (GI) to the time domain signal converted by the IFFT unit 354-1. The signal replicas s _{i, v} output from the GI insertion unit 355-1 can be expressed by Expression (9).

但し、ベクトルｃ＾ｉ、ｖは、第ｖ要素が０の変調シンボルレプリカのベクトルである。なお、パイロットシンボル等の既知のシンボルを含んでもよい。

Here, vectors c ^ i, v are vectors of modulation symbol replicas whose vth element is 0. A known symbol such as a pilot symbol may be included.

  The same processing is performed on the mobile station apparatus 100-2 by the interleaving unit 351-2, the symbol replica generation unit 352-2, the DFT unit 353-2, the IFFT unit 354-2, and the GI insertion unit 355-2. Do.

  When the received SC-FDM signal shown in FIG. 2 has the frame format of FIG. 2, the discrete spectrum replica output by the DFT unit 353-2 is the resource elements (K1, L1) and (K1 = 24) of subframe # 2. ..., 264... 275, L1 = 0... 13 (except for resource elements in which pilot symbols are arranged).

  Interference replica generation section 356 generates an interference replica of the interference component received by the SC-FDM signal received by base station apparatus 300 using the signal output from GI insertion section 355-n and the impulse response estimated value. Interference components include intersymbol interference and intercarrier interference, and an interference replica is generated for each interference component.

  For example, when the SC-FDM signal is subjected to inter-symbol interference, the signal output from the GI insertion unit 355-n in the u-th iterative process of the interference removal unit 305 is represented by s u, n and the channel estimation value Assuming that h ^ n, the intersymbol interference replicas r u and d generated by the interference replica generation unit 356 are expressed by the following equation (10).

ただし、初回処理の場合（ｕ＝０）、ｒ＾０＝０であり、ｈ＾ｉはインパルス応答推定値である。

However, in the case of the initial processing (u = 0), r ^ 0 = 0, and h ^ i is an impulse response estimated value.

  The replica generation of equation (10) is performed for all v and is subtracted from the received signal ri.

  In the above description, the case where the inter-symbol interference is removed by subtracting the time domain interference replica from the received signal is shown, but the present invention is not limited to this case. For example, inter-symbol interference may be removed using a frequency domain interference replica in addition to a time domain interference replica.

  FIG. 9 is a flowchart showing the operation of the base station apparatus 300. When receiving the transmission signal from mobile station apparatus 100, base station apparatus 300 performs propagation path estimation using the pilot signal included in the transmission signal (step S201). In the propagation path estimation, pilot signals in which data signals of the mobile station device 100 are scattered in a plurality of resource blocks in the same subframe are used.

  Next, in the repeated interference removal process in the interference removal unit 305, the number of repetitions is determined (step S202), and if it is the initial process (u = 0), the received signal is output as it is. This signal is input to the FFT unit 307 after being processed by the GI removal unit 306. On the other hand, if it is an iterative process (u> 0), interference cancellation is performed using an interference replica generated from the coded bit LLR calculated by the decoding process on the data signal of each mobile station apparatus 100 in the u−1th iterative process. Is performed (step S203).

  Next, FFT processing is performed in the FFT unit 307 on the signal subjected to the processing in step S202 and step S203 (step S204), and propagation path distortion is performed in the propagation path compensation unit 308 on the signal converted into the frequency domain. Compensation (equalization processing) is performed (step S205). The equalization process is performed using a frequency response calculated by the propagation path estimation. An equalized signal for each mobile station device 100 is extracted from the frequency domain signal (equalized signal) that has been subjected to equalization processing, subjected to IDFT processing, demodulation processing, and decoding processing (step S206), and then subjected to interference removal. When the predetermined number of repetitions has been completed in the process (YES in step S207), the result of the hard decision of the decoding process result of each mobile station device 100 is passed to the MAC unit or the like, the process is terminated, and the next data is awaiting reception. . On the other hand, if the predetermined number of repetitions has not ended (NO in step S207), it is determined whether there is an error in the data signal of each mobile station device 100 (step S208). The result of the hard decision of the decoding process result is passed to the MAC unit or the like, the process is terminated, and the next data is awaiting reception. On the other hand, when there is an error, a modulation symbol replica for the data signal of each mobile station apparatus 100 is generated using the encoded bit LLR output from the decoding unit 323-n (step S209). And an interference replica is produced | generated using the modulation symbol replica with respect to the data signal of each said mobile station apparatus 100 (step S210), it inputs into the interference removal part 305, and an interference removal process is performed again (it returns to step S202). That is, the processing is repeated until a predetermined number of times is satisfied, or it is determined that there is no error in the data signal, or one of the conditions is satisfied.

  As described above, in the present embodiment, in the base station apparatus 300 that performs repetitive processing (turbo equalization) using the impulse response of the propagation path, the impulse response estimation is performed using pilot signals arranged over a plurality of resource blocks. . Thereby, even when the band of each resource block is narrower than the FFT band, the impulse response can be estimated with high accuracy.

(Second Embodiment)
FIG. 10 is a diagram showing a frame format in uplink r2 and r4 in the communication system according to the second embodiment of the present invention (assuming the communication system of FIG. 1).
The horizontal axis is time, and the vertical axis is frequency. In the frame format of FIG. 10, an uplink control channel and an uplink common channel are allocated. Hereinafter, differences from FIG. 2 will be described.

  In FIG. 10, the mobile station apparatus 100-1 transmits to the base station apparatus 300 hatched portions that are diagonally upward to the right (subcarrier indexes 24 to 47 of subframe # 1 and subcarrier indexes 264 to 275 of subframe # 3). It is a resource element that allocates information data to be processed. Further, the painting unit is a resource element (for example, DMRS (Demodulation Reference Signal)) in which pilot signal 1 transmitted by mobile station apparatus 100-1 is arranged.

  The mobile station apparatus 100-2 transmits to the base station apparatus 300 hatched portions that are diagonally left upward (subcarrier indexes 264 to 275 of subframe # 1, subcarrier indexes 24 to 47 and 264 to 275 of subframe # 2). It is a resource element that allocates information data to be processed. The shaded part is a resource element that arranges a pilot signal 2 transmitted by the mobile station apparatus 100-2.

  Note that the scheduling of resource elements to which the information data and the pilot signal are allocated is set by the base station apparatus 300 based on CQI and the like transmitted from each mobile station apparatus 100 to the base station apparatus 300. The resource element to which the information data and the like of each mobile station device 100 is allocated is notified by the uplink control information channel.

  Next, propagation path estimation of the base station apparatus 300 in the second embodiment will be described.

  The propagation path estimation unit in the second embodiment performs propagation path estimation using pilot signals arranged in different frequency bands and different subframes.

  The propagation path estimation unit 304 in the second embodiment will be described when the base station apparatus 300 receives a signal in the frame format of FIG.

  The FFT unit 331 performs FFT processing on the down-converted SC-FDM signal input from the receiving unit 302 to convert the time domain signal into the frequency domain.

  The pilot signal extraction unit 332 extracts pilot signals arranged in different frequency bands and different subframes for each mobile station apparatus 100 from the frequency domain signals.

  In order to calculate a propagation path estimated value (impulse response estimated value or frequency response estimated value) used when data signal is detected by mobile station apparatus 100-1, the third and tenth SC-FDM symbols in subframe # 1 Pilot signals arranged in subcarrier indexes 24 to 47 and subcarrier indexes 264 to 275 of the third and tenth SC-FDM symbols in subframe # 3 are extracted.

  Also, in order to calculate a propagation path estimated value (impulse response estimated value or frequency response estimated value) used when detecting a data signal of mobile station apparatus 100-2, the third and tenth SC-FDMs in subframe # 1 are used. Pilot signals arranged at subcarrier indexes 264 to 275 of symbols and subcarrier indexes 24 to 47 and 264 to 275 of third and tenth SC-FDM symbols in subframe # 2 are extracted.

  Next, pilot frequency response calculation section 333 uses the extracted pilot signal and the corresponding pilot signal held by base station apparatus 300, and based on equation (3), the frequency response of the subcarrier in which the pilot signal is arranged Is calculated.

  Here, pilot signals arranged in different subframes and in the same subcarrier index are weighted and combined for each subcarrier.

  When both pilot signals arranged in subcarrier index 264 to 275 of subframe # 1 and pilot signals arranged in subcarrier index 264 to 275 of subframe # 2 are extracted, the frequency response of the same subcarrier index Are weighted and combined (equal weighting is equivalent to the average). This makes it possible to improve the SNR in calculating the frequency response at the subcarrier index.

  Next, the impulse response estimation unit 334 estimates an impulse response based on the equation (4) using the frequency response estimation value.

  When estimating the impulse response used for interference cancellation processing for the data signal of mobile station apparatus 100-1 arranged in subframe # 1, subcarrier index 24-47 of subframe # 1 and subcarrier index 264 of subframe 3 The frequency response calculated by the pilot signal arranged at 275 is used.

  Also, when estimating an impulse response used for interference cancellation processing for the data signal of mobile station apparatus 100-1 arranged in subframe # 3, subcarrier indexes 24-47 of subframe # 1 and subcarrier of subframe # 3 The frequency response calculated from the pilot signals arranged at indexes 264 to 275 is used.

  Also, when estimating an impulse response used for interference cancellation processing for the data signal of mobile station apparatus 100-2 arranged in subframe # 1, subcarrier indexes 264 to 275 of subframe # 1 and subcarrier of subframe # 2 The frequency response calculated by the pilot signals arranged at indexes 24-47 and 264-275 is used.

  Also, when estimating an impulse response used for interference cancellation processing for the data signal of mobile station apparatus 100-2 arranged in subframe # 2, subcarrier indexes 264 to 275 of subframe # 1 and subcarrier of subframe # 2 The frequency response calculated by the pilot signals arranged at indexes 24-47 and 264-275 is used.

  The data frequency response estimation unit 335 calculates a frequency response of subcarriers in which data is arranged from the impulse response estimation value.

  FIG. 11 is a diagram showing the relationship among the system band, FFT band, and pilot signal band in the present invention. FIG. 11 shows a pilot signal band for mobile station apparatus 100 in FIG. The painted portion is a resource block in which pilot signals are arranged, and the white portion is a resource block in which other signals are arranged. Here, the FFT bandwidth (number of FFT points) is 2048 points and the system bandwidth (number of subcarriers) is 300.

  Band A is a pilot signal band transmitted by mobile station apparatus 100 in subframe # 1, and band B is a pilot signal band transmitted by mobile station apparatus 100 in subframe # 2. The pilot signal extraction unit 332 extracts the band A and band B pilot signals. The pilot frequency response calculation unit 333 calculates the frequency response of the band A and the band B. The impulse response estimation unit 334 performs impulse response estimation by performing IFFT on the frequency responses of the bands A and B. That is, the pilot signal bandwidth at the time of impulse response estimation is band A + band B, and the ratio to the FFT bandwidth can be expanded.

  As described above, when data signals are arranged in a plurality of resource blocks composed of different frequency bands and different subframes, impulse response estimation is performed using pilot signals arranged in different subframes. The bandwidth in which the pilot signal is arranged can be expanded with respect to the IFFT bandwidth. As a result, when the impulse response is estimated, it is possible to suppress the arrival path from being widened, and it is possible to improve the estimation accuracy.

  In addition, the other site | part of the base station apparatus 300 in 2nd Embodiment, and each site | part of the mobile station apparatus 100-1 and the mobile station apparatus 100-2 have a function equivalent to 1st Embodiment.

(Third embodiment)
FIG. 12 is a block diagram showing a configuration example of the mobile station apparatus 500 according to the third embodiment of the present invention. The mobile station apparatus 500 includes an upper layer 102, a symbol generation unit 103, a precoding unit 501, a resource mapping unit 105-m, an IFFT (Inverse Fast Fourier Transform) unit 106-m, a GI insertion unit 107-m, and a transmission unit 108-. m, a pilot symbol generation unit 109, and a control symbol generation unit 110. The transmission antenna unit 101-m is connected to the transmission unit 108-m. The mobile station device 500 includes a receiving unit 122 and a control signal detecting unit 123, and the receiving antenna unit 121 is connected to the receiving unit 122. Here, m is the number of transmission antennas. FIG. 12 shows a case where m = 2.

  A mobile station apparatus 500 according to the third embodiment adds a precoding unit 501 to the mobile station apparatus 100 according to the first embodiment, and a resource mapping unit based on the precoding process of the precoding unit 501. The number of 105-m, IFFT (Inverse Fast Fourier Transform) unit 106-m, GI insertion unit 107-m, transmission unit 108-m, and transmission antenna unit 101-m is set differently. Hereinafter, different parts will be mainly described.

  The precoding unit 501 includes a spectrum of data modulation symbols output from the symbol generation unit 103, a pilot signal output from the pilot symbol generation unit 109, and a control signal output from the control symbol generation unit 110 (hereinafter referred to as all of these). , Called spectrum, etc.) is multiplied by a precoding matrix specific to the mobile station device (user specific).

  FIG. 13 is a diagram illustrating an example of a precoding matrix. By multiplying one input such as a spectrum by the matrix of FIG. 13, two precoded spectra and the like are output. Based on the number of outputs, the number of resource mapping unit 105-m, IFFT (Inverse Fast Fourier Transform) unit 106-m, GI insertion unit 107-m, transmission unit 108-m, and transmission antenna unit 101-m is set. The

  The precoding matrix to be multiplied is known in the communication system of the present invention, and is notified by the downlink control channel that mobile station apparatus 500 receives from base station apparatus 300. Base station apparatus 300 selects a precoding matrix for multiplying a spectrum or the like transmitted by each mobile station apparatus 500 from a propagation path estimation result using a pilot signal transmitted by mobile station apparatus 500. For example, the base station apparatus 300 selects a matrix that increases the coding gain by multiplying the precoding matrix from the propagation path estimation result. That is, a matrix in which the propagation path estimation result and the coding matrix are in phase is selected.

  The resource mapping unit 105-m maps the precoded spectrum output from the precoding unit 501 to resources based on the signal allocation information notified from the higher layer 102. For example, when transmitting in the frame format of FIG. 10, the spectrum after precoding is allocated to subcarrier indexes # 24 to # 47 of subframe # 1 and subcarrier indexes # 264 to # 275 of subframe # 3. . The signal output from the resource mapping unit 105-m is the IFFT (Inverse Fast Fourier Transform) unit 106-m, the GI insertion unit 107-m, the transmission unit 108-m, and the transmission antenna unit 101-m according to the first embodiment. Processing equivalent to that shown in is performed.

  Next, the base station apparatus 300 according to the third embodiment of the present invention will be described. The base station apparatus 300 according to the third embodiment has a configuration equivalent to that of the base station apparatus 300 according to the first embodiment.

  The base station apparatus 300 according to the third embodiment receives the SC-FDM signal output from the transmission antenna unit 101-1 and the transmission antenna unit 101-2 by the mobile station apparatus 500 of FIG. become. Since the base station apparatus 300 notifies the mobile station apparatus 500 of a precoding matrix that increases the precoding gain and receives the SC-FDM signal precoded by the precoding matrix, the base station apparatus 300 can obtain the diversity gain. it can. That is, diversity gain can be obtained also in the pilot signal.

  The propagation path estimation unit 304 included in the base station apparatus 300 according to the third embodiment performs impulse response estimation and frequency response estimation by the processing shown in the first embodiment. In the embodiment according to the third embodiment, impulse response estimation and frequency response estimation are performed using the pilot signal obtained with the diversity gain.

  As described above, in the present embodiment, in the base station apparatus 300 that performs iterative processing (turbo equalization) using the impulse response of the propagation path, the impulse response estimation is a pilot signal arranged over a plurality of resource blocks. The pilot signal multiplied by the precoding matrix is used. Thereby, the bandwidth in which the high gain pilot signal is arranged can be expanded with respect to the IFFT bandwidth. As a result, when the impulse response is estimated, it is possible to suppress the arrival path from being widened, and it is possible to improve the estimation accuracy.

(Fourth embodiment)
In the communication system according to the fourth embodiment of the present invention, in FIG. 1, the mobile station device 100 transmits a data signal by a base station device 300 and a hybrid automatic repeat request HARQ (Hybrid Automatic Repeat reQuest).

  The mobile station apparatus 100 according to the fourth embodiment of the present invention has the functions of the upper layer 102, the encoding unit 111, the control symbol generation unit 110, and the control signal detection unit 123 of the mobile station apparatus 100 according to the first embodiment. Different. Other parts have similar functions. Hereinafter, different parts will be mainly described.

  The control signal detection unit 123 performs a demodulation process, a decoding process, and the like on the control signal transmitted from the base station apparatus 300 output from the reception unit 122, and the downlink common channel (PDSCH) and the downlink control channel (PDCCH). Then, a response signal (ACK / NACK signal) included in one of the synchronization channels (SCH) is detected. The response signal is a signal for notifying whether or not the data signal transmitted from the mobile station apparatus 100 to the base station apparatus 300 has been received without error.

  The upper layer 102 receives parameters (MCS, spatial multiplexing number, pilot signal sequence, frequency) of uplink data signals to be transmitted to each base station apparatus 300 included in any of the channels input from the control signal detection unit 123. Get the allocation). Further, the upper layer 102 acquires the necessity of retransmission from the response signal detected by the control signal detection unit 123 and calculates the number of retransmissions. Specifically, when a response signal (ACK signal) indicating that the signal has been correctly received is obtained, new information data is input to the encoding unit 111, and the fact is notified to the encoding unit 111. On the other hand, when a response signal (NACK signal) indicating that the signal could not be received correctly is obtained, this is notified to the encoding unit 111.

  The upper layer 102 inputs the number of retransmissions to the control symbol generator 110 in addition to various control data such as MCS information and rank information for the information data.

  FIG. 14 is a block diagram showing a configuration example of the encoding unit 111 according to the fourth embodiment of the present invention. The encoding unit 111 includes an error detection encoding unit 601, an error correction encoding unit 603, an encoded bit storage unit 605, and a puncturing unit 607.

  The error detection encoding unit 601 performs error detection encoding such as CRC (Cyclic Redundancy Check) on the information data so that the base station apparatus 300 that has received the information data can detect whether or not there is an error. The error detection bit is added to the information data and output. The error correction coding unit 603 performs error correction coding such as a turbo code, a convolutional code, and an LDPC (Low Density Parity Check) code on the output data from the error detection coding unit 601.

  FIG. 15 shows an internal configuration of the error correction encoding unit 603 when a turbo code is applied as an encoding method when the error correction encoding unit 603 performs error correction encoding at a coding rate R = 1/3. FIG. The error correction encoding unit 603 includes internal encoders 611-1 and 611-2 and an internal interleaver 613. When the error detection encoded information bit sequence from the error detection encoding unit 601 is input, The error correction coding unit 603 outputs three types of information bit sequences of systematic bits x, parity bits z, and parity bits z ′. Here, the systematic bit x is the bit sequence itself input from the error detection encoding unit 601. The parity bit z is an output result of the internal encoder 611-1 encoding the bit sequence from the error detection encoding unit 601. For the parity bit z ′, the internal interleaver 613 first interleaves the bit sequence from the error detection encoding unit 601, and the output result obtained by performing the encoding process by the internal encoder 611-2 to which the interleaved processing result is input. It is. Here, the internal encoder 611-1 and the internal encoder 611-2 may be the same encoder that performs the encoding of the same encoding method, or may be different encoders. Preferably, a recursive convolutional encoder is used for both the inner encoder 611-1 and the inner encoder 611-2. Hereinafter, the error correction encoding unit 603 will be described using a turbo code with the configuration shown in FIG.

  Returning to FIG. 14, the puncturing unit 607 thins out the encoded bits that are output from the error correction encoding unit 603 based on a predetermined pattern group that is held (referred to as puncturing processing). Controls the amount of data to be transmitted (controls the coding rate). In addition, when a NACK signal is input, the puncturing unit 607 performs puncturing processing on the coded bits stored in the coded bit storage unit 605 based on the predetermined pattern group described above. The predetermined pattern group held by the puncture unit 607 will be described later. The coded bit storage unit 605 stores the coded bits generated by the error correction coding unit 603, and outputs a coded bit corresponding to the stored request when requested by the puncturing unit 607. Note that the NACK signal from the upper layer 102 is input to the encoded bit storage unit 605, and the encoded bit storage unit 605 receives the input of the signal and outputs the stored encoded bits to the puncture unit 607. You may do it.

  FIG. 16 is a diagram illustrating an example of the predetermined pattern group described above held by the puncturing unit 607. In FIG. 16, after the error correction coding unit 603 shown in FIG. 15 performs turbo coding at a coding rate R = 1/3, the puncturing unit 607 performs coding rate R = 1/2 or R = An example of a puncture pattern used for puncture processing when puncture processing is performed on 3/4 is shown. In FIG. 16, x is a bit string representing puncturing processing for data input from the error detection encoding unit 601 to the error correction encoding unit 603, that is, systematic bits composed of error detection bits and information data. In this bit string x, “1” indicates that the bit at the corresponding position remains, and “0” indicates that the bit at the corresponding position is thinned out.

  z and z ′ are bit strings representing puncturing processing for redundant bits (parity bits z and parity bits z ′ in FIG. 15) generated from the systematic bits by the error correction coding unit 603. The values ‘1’ and ‘0’ of the bits in the bit string z and z represent the bits to be left and the bits to be thinned out, as in the bit string x. The puncturing unit 607 performs puncturing processing represented by these bit strings x, z, and z ′ on the systematic bits and redundant bits output from the error correction encoding unit 603 or the encoded bit storage unit 605. A bit at a bit position “1” in the puncture pattern shown in FIG.

  Note that the puncture pattern group in FIG. 16 is an example, and among the puncture pattern group, a pattern group (pattern corresponding to HARQ type II) in which only some patterns leave systematic bits, and all patterns are always systematic. It may be a pattern group (pattern corresponding to HARQ type III) that is a pattern that leaves bits.

As typical retransmission methods in the hybrid automatic retransmission request HARQ, there are Chase combining CC (Chase Combining) and incremental redundancy IR (Incremental Redundancy). When Chase combining CC is applied as a retransmission method, the puncturing unit 607 performs puncturing processing on the data of the initial transmission signal in accordance with, for example, the pattern 1 of R = 3/4 in FIG. Only the bits indicated by “1” in the above are output. The output signal from the puncturing unit 607 subjected to the puncturing process with the pattern 1 is transmitted from the transmitting antenna unit 101-1 by the transmitting unit 108-1 after the symbol generating unit 103 and other processes are performed. When a NACK signal is input as a response signal to the initial transmission signal (when retransmission is requested), the puncture unit 607 transmits the encoded bit of the information data transmitted from the encoded bit storage unit 605 using the initial transmission signal. And a signal punctured with the same pattern 1 as the initial transmission signal is output as a retransmission signal.

  Thus, in the chase combining CC, the puncturing unit 607 continues to output a punctured signal in the same pattern as the initial transmission signal until an ACK signal is input. When the ACK signal is input, the output data of the error correction encoding unit 603 regarding the next information data different from the information data transmitted by the initial transmission signal is punctured based on the pattern 1 or the pattern 2. Perform processing.

  On the other hand, when increasing redundant IR is applied as a method of retransmission of the hybrid automatic retransmission request HARQ, the puncturing unit 607, for example, for pattern 1 of R = 3/4 in FIG. Therefore, puncturing is performed, and only the bits indicated by “1” in FIG. 16 are output. The output signal from the puncturing unit 607 subjected to the puncturing process with the pattern 1 is transmitted from the transmitting antenna unit 101-1 by the transmitting unit 108-1 after the symbol generating unit 103 and other processes are performed. When a NACK signal is input as a response signal to the initial transmission signal (when retransmission is requested), the puncture unit 607 transmits the encoded bit of the data transmitted by the initial transmission signal from the encoded bit storage unit 605. This time, the signal punctured with the pattern 2 of R = 3/4 in FIG. 16 is output as a retransmission signal.

  In this manner, the puncturing unit 607 continues to alternately output the signal punctured with the pattern 1 and the signal punctured with the pattern 2 until the ACK signal is input. When the ACK signal is input, the puncture process is performed on the output data of the error correction encoding unit 603 for the next information data different from the information data transmitted by the initial transmission packet signal based on the pattern 1. Do. When a predetermined number of NACK signals are input, the output data of error correction coding section 603 for different next information data may be transmitted without further retransmission.

  In addition to the function of the control symbol generation unit 110 in the first embodiment, the control symbol generation unit 110 performs error correction encoding and modulation mapping on control data indicating information on the number of retransmissions input from the higher layer 102, and performs control symbol Is generated.

  FIG. 17 is a block diagram showing a configuration example of a base station apparatus 700 according to the fourth embodiment of the present invention. In the base station apparatus 700 according to the fourth embodiment, a combining unit 701-n, an LLR storage unit 703-n, and a propagation path storage unit 705 are added to the base station apparatus 300 according to the first embodiment. Further, the functions of the propagation path estimation unit 304 and the upper layer 310 are different. Hereinafter, different parts will be mainly described.

  When the demodulated soft decision result (log likelihood ratio LLR) for the initial transmission signal is input from the deinterleaving unit 322-n from the deinterleaving unit 322-n, the combining unit 701-n does not perform any particular processing and decodes the input signal. Output to -n. On the other hand, when the demodulated soft decision result for the retransmission signal is input from the deinterleave unit 322-n, the input demodulated soft decision result and the initial transmission signal stored in the LLR storage unit 703-n and The soft decision result after demodulation of the retransmission signal and the synthesis process are performed.

For example, when a demodulated soft decision result for the p-th retransmission signal is input, the demodulated soft decision result for the p-th retransmission signal and the 1st to (p-1) th retransmissions from the LLR storage unit 703-n. The signal (including the initial transmission signal) is combined with the soft decision result after demodulation. If the output from the interleaver 322-n when receiving the p-th retransmission signal is g _p (m) (where m is the index of the encoded data and the maximum value is the encoded size), the p-th The combined unit output signal λ _p when the packet signal is received is expressed by Equation (11).

なお、上記では、すべての再送パケットの信号を合成する場合を示しているが、再送パケットの信号のいずれかのみの合成も可能である。

In the above description, the case where the signals of all the retransmission packets are combined is shown, but only one of the signals of the retransmission packets can be combined.

  The LLR storage unit 703-n stores the soft decision result after demodulation output from the deinterleave unit 322-n. In addition, when the deinterleaving unit 322-n inputs the soft decision result after demodulation for the retransmission signal to the synthesis unit 701-n, the LLR storage unit 703-n inputs the initial transmission signal for the retransmission signal to the synthesis unit 701-n. Then, the already received retransmission signal is output to combining section 701-n.

  When the base station apparatus 700 receives a retransmission signal, the propagation path estimation unit 304 uses the pilot frequency response calculated at the time of receiving the initial transmission signal and the already received retransmission signal for the retransmission signal, and the impulse response at the time of the retransmission signal Is estimated.

  FIG. 18 is a diagram illustrating a schematic configuration of the propagation path estimation unit 304 in the fourth embodiment. The propagation path estimation unit 304 in the fourth embodiment differs in the functions of the propagation path estimation unit 304 and the impulse response estimation unit 334 in the first embodiment.

  When the pilot signal included in the initial transmission signal is input from the reception unit 302 to the propagation path estimation unit 304, the impulse response estimation unit 334 performs an impulse response using only the frequency response output from the pilot frequency response calculation unit 333. presume.

  Further, when the pilot signal included in the retransmission signal is input from the reception unit 302 to the propagation path estimation unit 304, the impulse response estimation unit 334 receives the frequency response output from the pilot frequency response calculation unit 333 and the initial response to the retransmission signal. The impulse response is estimated using the pilot frequency response calculated when the transmission signal and the already received retransmission signal are received.

  The pilot frequency response calculated when receiving the initial transmission signal and the already received retransmission signal for the retransmission signal is stored in the propagation path storage unit 705.

  FIG. 19 is a diagram illustrating an example of a sequence of a communication system in which a hybrid automatic repeat request HARQ is performed between the mobile station device 100 and the base station device 700. First, the mobile station apparatus 100 generates an initial transmission signal and transmits it to the base station apparatus 700 (step S301). FIG. 20 is a diagram illustrating an example of allocation of a data signal, a pilot signal, and a control signal in the initial transmission signal. The control signal is allocated to subcarrier indexes 0 to 23 and 276 to 299 of all SC-FDM symbols constituting the subframe. The pilot signal is arranged at subcarrier indices 24-47 of the third and tenth SC-FDM symbols constituting the subframe (filled portion). Data signals are arranged in subcarrier indexes 24 to 47 of SC-FDM symbols excluding the SC-FDM symbols in which the pilot symbols are arranged (hatching portions diagonally upward to the left).

  Next, when the base station apparatus 700 receives the initial transmission signal of the mobile station apparatus 100 in the format of FIG. 20, the base station apparatus 700 performs interference removal processing, demodulation processing, decoding processing, and the like on the initial transmission signal (step S302). At this time, the impulse response and the frequency response of the propagation path used in the interference cancellation process and the demodulation process are performed using the pilot signals arranged in the subcarrier indexes 24 to 47 of the third and tenth SC-FDM symbols.

  Next, base station apparatus 700 transmits the decoding result in step S302 to mobile station apparatus 100. If there is an error in the decoding result, a response signal (NACK) indicating that the decoding has not been correctly performed is generated (step S303) and transmitted to the mobile station apparatus 100 (step S304). If there is no error, a response signal (ACK) indicating that reception was successful is generated (step S303) and transmitted to the mobile station apparatus 100 (step S304). FIG. 19 shows a case where a NACK signal is transmitted.

  Next, when receiving the NACK signal in step S304, the mobile station apparatus 100 generates a retransmission signal for the initial transmission signal (step S305) and transmits it to the base station apparatus 700 (step S306). FIG. 21 is a diagram illustrating an example of allocation of a data signal, a pilot signal, and a control signal in a retransmission signal. The control signal is allocated to subcarrier indexes 0 to 23 and 276 to 299 of all SC-FDM symbols constituting the subframe. The pilot signals are arranged in subcarrier indexes 24-35 and 264-275 of the third and tenth SC-FDM symbols constituting the subframe (filled portion). Data signals are arranged in subcarrier indexes 24 to 35 and 264 to 275 of the SC-FDM symbol excluding the SC-FDM symbol in which the pilot symbol is arranged (hatching portion diagonally upward to the left).

  Next, when receiving the retransmission signal of mobile station apparatus 100 in the format of FIG. 21, base station apparatus 700 performs interference removal processing, demodulation processing, decoding processing, and the like on the retransmission signal (step S307). At this time, the impulse response and frequency response of the propagation path used in the interference cancellation process and the demodulation process are the pilot signals arranged in the subcarrier indexes 24 to 47 of the third and tenth SC-FDM symbols in FIG. This is performed using subcarrier indexes 24-35 and 264-275 of the 21st third and 10th SC-FDM symbols.

  FIG. 22 is a diagram showing a pilot signal arrangement used for impulse response estimation when performing interference removal processing, demodulation processing, decoding processing, and the like in step S307. The FFT band is 2048 FFT points, and the system band is 300 subcarriers. The filled portion indicates a pilot signal used for propagation path estimation, and the white portion indicates null. Impulse response estimation is performed by performing IFFT processing according to the pilot arrangement of FIG.

  In the overlapping band of the initial transmission signal pilot signal and the retransmission signal pilot signal, both pilot signals may be weighted and combined, or only one of them may be used.

  In the upper layer 310, the MCS, rank information, and scheduling (resource block allocation) of the data signal transmitted from the mobile station apparatuses 100-1 and 100-2 to the base station apparatus 700 are transmitted in the uplink control channel transmitted by the mobile station apparatus 100. Determined by CQI, RI, etc. In the upper layer 310 in the fourth embodiment, in addition to the information, scheduling of the data signal for the first transmission can be considered.

  Specifically, in the initial transmission, when the data signal transmitted by mobile station apparatus 100 is allocated with the resources shown in FIG. 20 (subcarrier indexes 24 to 47), in retransmission, priority is given to subcarrier indexes 48 to 275. Assign.

  Thereby, at the time of retransmission, the pilot signal band can be widened by using the pilot signal transmitted in the initial transmission and retransmission.

  As described above, at the time of the retransmission signal, the impulse response is estimated using the pilot signal arranged at the time of the initial transmission signal. Thereby, at the time of retransmission, the band in which the pilot signal is arranged can be expanded with respect to the FFT bandwidth. As a result, when the impulse response is estimated, it is possible to suppress the arrival path from being widened, and it is possible to improve the estimation accuracy. When the impulse response estimation accuracy is improved, the reception performance at the time of retransmission is improved. If the reception performance at the time of retransmission is improved, the number of retransmissions of the hybrid automatic retransmission request HARQ can be reduced, and transmission efficiency can be improved.

  The characteristic operations of the present invention as described above can also be performed by causing a computer to execute a program. That is, the control program for the receiving apparatus according to the present embodiment is a control program for the receiving apparatus that estimates an impulse response using a pilot signal arranged in a band narrower than a band for performing FFT (Fast Fourier Transform). A process of receiving information data and a pilot signal allocated in a predetermined resource unit, a process of calculating a propagation path estimation value using the pilot signal, a process of detecting the information data, and the information data signal A sequence of processing for estimating an impulse response using a pilot signal transmitted by the same transmitting apparatus as the transmitting apparatus and belonging to a resource different from the resource to which the information data signal is allocated The process is converted into a computer readable and executable command. And

  In this way, since the impulse response is estimated using a pilot signal belonging to a resource different from the resource to which the information data signal is assigned, the pilot signal is arranged in a band narrower than the band for performing FFT. However, the accuracy of propagation path estimation can be maintained.

  Further, the control program of the receiving apparatus according to the present embodiment includes a process of receiving information data and a pilot signal allocated in a predetermined resource unit in initial transmission and retransmission for the initial transmission, and the initial transmission and retransmission. And a process of estimating an impulse response using the received pilot signal.

  As described above, since the impulse response is estimated using the pilot signal received by the initial transmission and the retransmission, it is possible to expand the band in which the pilot signal is arranged with respect to the bandwidth for performing the FFT during the retransmission. It becomes. As a result, when the impulse response is estimated, it is possible to suppress the arrival path from being widened, and it is possible to improve the propagation path estimation accuracy. When the impulse response estimation accuracy is improved in this way, the reception performance at the time of retransmission is improved. For example, the number of retransmissions of hybrid ARQ can be reduced, and the transmission efficiency can be improved.

  In the above-described embodiment, the configuration and the like illustrated in the accompanying drawings are not limited to these, and can be changed as appropriate within the scope of the effects of the present invention. In addition, various modifications can be made without departing from the scope of the object of the present invention.

  In addition, a program for realizing the functions described in the present embodiment is recorded on a computer-readable recording medium, and the program recorded on the recording medium is read into a computer system and executed to execute processing of each unit. May be performed. The “computer system” here includes an OS and hardware such as peripheral devices.

  Further, the “computer system” includes a homepage providing environment (or display environment) if a WWW system is used.

  The “computer-readable recording medium” refers to a storage device such as a flexible medium, a magneto-optical disk, a portable medium such as a ROM and a CD-ROM, and a hard disk incorporated in a computer system. Furthermore, the “computer-readable recording medium” dynamically holds a program for a short time like a communication line when transmitting a program via a network such as the Internet or a communication line such as a telephone line. In this case, a volatile memory in a computer system serving as a server or a client in that case, and a program that holds a program for a certain period of time are also included. The program may be a program for realizing a part of the above-described functions, or may be a program that can realize the above-described functions in combination with a program already recorded in a computer system.

  The functions of all or part of the transmitting apparatus in FIGS. 3, 12, 14, and 15 and all or part of the receiving apparatus in FIGS. 4, 5, 7, 8, 17, and 18 are also possible. May be realized in an integrated circuit. Each functional block of the transmission device and the reception device may be individually formed into chips, or a part or all of them may be integrated into a chip. Further, a chip control circuit that controls each functional block of the transmitting device and the receiving device formed into chips may be integrated. The chip control circuit controls at least the interference removal unit 305. The method of designating and integrating circuits 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.

100, 100-1, 100-2 Mobile station apparatus 101, 101-1, 101-m Transmission antenna unit 102 Upper layer 103 Symbol generation unit 105, 105-1, 105-2, 105-m Resource mapping unit 106-1 , 106-2 IFFT unit 107-1, 107-2 GI insertion unit 108-1, 108-2 transmitting unit 109 pilot symbol generating unit 110 control symbol generating unit 111 encoding unit 112 interleaving unit 113 modulating unit 114 DFT unit 121 receiving antenna Unit 122 reception unit 123 control signal detection unit 300 base station device 301 reception antenna unit 302 reception unit 303 reception signal storage unit 304 propagation path estimation unit 305 interference removal unit 306 GI removal unit 307 FFT unit 308 propagation path compensation unit 309-1, 309-2 Signal detection unit 310 Upper layer 311 transmission Antenna unit 312 Control signal generating unit 313 Transmitting unit 320-1, 320-2 IDFT unit 321-1, 321-2 Demodulating unit 322-1, 322-2 Deinterleaving unit 323-1, 323-2 Decoding unit 331 FFT unit 332 Pilot signal extraction unit 333 Pilot frequency response calculation unit 334 Impulse response estimation unit 335 Data frequency response estimation unit 341 Subtraction unit 342 Replica generation units 351-1 and 351-2 Interleave units 352-1 and 352-2 Symbol replica generation unit 353 -1,353-2 DFT section 354-1, 354-2 IFFT section 355-1, 355-2 GI insertion section 356 Interference replica generation section 500 Mobile station apparatus 501 Precoding section 601 Error detection coding section 603 Error correction code Encoding unit 605 Encoded bit storage unit 607 Punk 611, 611-1, 611-2 Inner encoder 613 Inner interleaver 700 Base station apparatus 701-1, 701-2, 701-n Combining unit 703-1, 703-2, 703-n LLR storage unit 705 Propagation path storage

Claims (17)

A receiving apparatus that estimates an impulse response using a pilot signal arranged in a band narrower than a band for performing FFT (Fast Fourier Transform),
A receiving unit for receiving information data and pilot signals allocated in predetermined resource units;
A propagation path estimator that calculates a propagation path estimated value using the pilot signal;
A signal detection unit for detecting the information data,
The propagation path estimation unit is a pilot signal transmitted by the same transmission apparatus as the transmission apparatus that has transmitted the information data signal, and uses a pilot signal that belongs to a resource different from the resource to which the information data signal is allocated. A receiving apparatus that performs impulse response estimation.   The receiving apparatus according to claim 1, wherein the propagation path estimation unit estimates the impulse response using a pilot signal belonging to a resource having a frequency band different from that of the resource to which the information data is allocated.   The receiving apparatus according to claim 1, wherein the propagation path estimation unit estimates the impulse response using a pilot signal belonging to a resource whose subframe is different from the resource to which the information data signal is allocated. .   The said propagation path estimation part estimates the said impulse response using the pilot signal which belongs to the resource from which the frequency band and sub-frame differ from the resource to which the said information data was allocated. Receiver device. The reception unit receives information data and pilot signals allocated in predetermined resource units in initial transmission and retransmission for the initial transmission,
The receiving apparatus according to claim 1, wherein the propagation path estimation unit estimates an impulse response using a pilot signal received by the initial transmission and the retransmission.   The receiving apparatus according to claim 5, wherein the signal detection unit detects information data in the initial transmission using the estimated impulse response.   The receiving apparatus according to claim 5, wherein the signal detection unit detects information data in the retransmission using the estimated impulse response.   The receiving apparatus according to claim 1, further comprising: a propagation path compensation unit that performs propagation path compensation using the estimated value of the impulse response.   The receiving apparatus according to claim 8, further comprising an interference removing unit that performs an interference removing process using the estimated value of the impulse response. The interference removing unit
A replica generation unit that generates an interference replica using the soft decision result of the information data output by the signal detection unit and the estimated value of the impulse response;
The receiving device according to claim 9, further comprising: a subtracting unit that subtracts the interference replica from the received signal. A transmission apparatus that arranges a pilot signal in a band narrower than a band in which the reception apparatus performs FFT (Fast Fourier Transform), and transmits the signal to the reception apparatus;
A communication system comprising the receiving device according to claim 1. The transmitter is
In the initial transmission and retransmission for the initial transmission, information data and pilot signals are allocated and transmitted to the receiving device in units of predetermined resources,
The receiving device is:
In the initial transmission and retransmission for the initial transmission, information data and pilot signals allocated in predetermined resource units are received, and an impulse response is estimated using the pilot signals received in the initial transmission and the retransmission. The communication system according to claim 11. The transmitter is
13. The communication system according to claim 12, wherein the resource of information data in the retransmission is allocated to a resource having a frequency band different from that of the resource to which the information data in the initial transmission is allocated. A control program for a receiving apparatus that estimates an impulse response using a pilot signal arranged in a band narrower than a band for performing FFT (Fast Fourier Transform),
A process of receiving information data and pilot signals allocated in predetermined resource units;
Processing to calculate a propagation path estimated value using the pilot signal;
Processing for detecting the information data;
An impulse response is estimated using a pilot signal transmitted by the same transmission apparatus as the transmission apparatus that has transmitted the information data signal and belonging to a resource different from the resource to which the information data signal is allocated. A control program for a receiving apparatus, characterized in that a series of processes is converted into a command that can be read and executed by a computer. In the initial transmission and retransmission for the initial transmission, processing for receiving information data and pilot signals allocated in predetermined resource units;
The control program for a receiving apparatus according to claim 14, further comprising a process of estimating an impulse response using a pilot signal received by the initial transmission and the retransmission. An integrated circuit that, when mounted on a receiving device, causes the receiving device to perform a plurality of functions,
A function of estimating an impulse response using a pilot signal arranged in a band narrower than a band for performing FFT (Fast Fourier Transform);
A function of receiving information data and pilot signals allocated in predetermined resource units;
A function of calculating a channel estimation value using the pilot signal;
A function of detecting the information data;
An impulse response is estimated using a pilot signal transmitted by the same transmission apparatus as the transmission apparatus that has transmitted the information data signal and belonging to a resource different from the resource to which the information data signal is allocated. An integrated circuit characterized by causing the receiving device to exhibit a function. In the initial transmission and retransmission for the initial transmission, a function of receiving information data and pilot signals allocated in predetermined resource units;
The integrated circuit according to claim 16, further comprising a function of estimating an impulse response using a pilot signal received by the initial transmission and the retransmission.

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