WO2007136056A1 - 受信機及び受信方法 - Google Patents
受信機及び受信方法 Download PDFInfo
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- WO2007136056A1 WO2007136056A1 PCT/JP2007/060429 JP2007060429W WO2007136056A1 WO 2007136056 A1 WO2007136056 A1 WO 2007136056A1 JP 2007060429 W JP2007060429 W JP 2007060429W WO 2007136056 A1 WO2007136056 A1 WO 2007136056A1
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- replica
- incoming wave
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Classifications
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L5/00—Arrangements affording multiple use of the transmission path
- H04L5/0001—Arrangements for dividing the transmission path
- H04L5/0014—Three-dimensional division
- H04L5/0016—Time-frequency-code
- H04L5/0021—Time-frequency-code in which codes are applied as a frequency-domain sequences, e.g. MC-CDMA
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
- H04B1/69—Spread spectrum techniques
- H04B1/707—Spread spectrum techniques using direct sequence modulation
- H04B1/7097—Interference-related aspects
- H04B1/7103—Interference-related aspects the interference being multiple access interference
- H04B1/7107—Subtractive interference cancellation
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L1/00—Arrangements for detecting or preventing errors in the information received
- H04L1/004—Arrangements for detecting or preventing errors in the information received by using forward error control
- H04L1/0045—Arrangements at the receiver end
- H04L1/0047—Decoding adapted to other signal detection operation
- H04L1/005—Iterative decoding, including iteration between signal detection and decoding operation
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/26—Systems using multi-frequency codes
- H04L27/2601—Multicarrier modulation systems
- H04L27/2647—Arrangements specific to the receiver only
Definitions
- the present invention relates to a receiver and a receiving method, and more particularly to a receiver and a receiving method for transmitting and receiving a signal by a multicarrier scheme.
- ISI Inter-symbol interference
- ICI Inter-Carrier Interference
- FIG. 20 is a diagram illustrating a signal that reaches a wireless receiver from a wireless transmitter via a multipath environment.
- time is taken on the horizontal axis.
- Symbols sl to s4 indicate signals that reach the radio receiver from the radio transmitter via the multipath environment, and arrive via four multipaths.
- a guard interval GI that copies the second half of the symbol is added in front of the symbol!
- the first signal si from the top shows a direct wave
- the second signal s2 shows a delayed wave with a delay tl within the guard interval GI.
- Signals s3 and s4, which are the third and fourth delayed waves, indicate the delayed waves with delays t2 and t3 exceeding the guard interval GI.
- the direct wave and the delayed wave are called incoming waves.
- the shaded area in front of the third and fourth delayed signals s3 and s4 indicates the part where the symbol preceding the desired symbol has entered the FFT section of the desired symbol, and section t4 indicates the FFT section of the desired symbol.
- the shaded portion is the ISI component. Since the ISI component is an interference component, it causes deterioration of characteristics during demodulation.
- the third and fourth delayed signals s3, s In 4 there will be a break in the symbol in the interval t4, which causes the above ICI.
- FIG. 21 (a) and Fig. 21 (b) show a state in which subcarriers are orthogonal to each other and a state in which interference occurs between subcarriers due to ICI in signal transmission / reception using a multicarrier scheme.
- FIG. Fig. 21 (a) shows that no ICI occurs and no interference occurs between subcarriers
- Fig. 21 (b) shows that ICI causes interference between subcarriers.
- Patent Document 1 proposes a method for improving characteristic degradation due to ISI and ICI when a delayed wave exceeding the guard inverter GI exists.
- the I SI component and a duplicate signal (replica signal) of an undesired subcarrier including the ICI component are used. After creating this, the characteristics are improved by ISI and ICI by demodulating the received signal again.
- MC—CDM Multi Carrier-Code Division Multiplexing
- MC—CDMA Multi Carrier-Code Division Multiple Access
- Spread-- is a combination of the multi-carrier transmission method and CDM (Code Division Multiplexing) method.
- OF CDM Orthogonal Frequency and Code Division Multiplexing
- FIG. 22 (a) and FIG. 22 (b) are diagrams illustrating the relationship between the subcarriers in the MC-CDMA system and the orthogonal codes corresponding to the subcarriers.
- the horizontal axis represents frequency.
- Figure 22 (a) shows, as an example, eight subkeys in the MC-CDM system. Shows the area.
- (b) of FIG. 22 shows three types of C8, 1, C8, 2, and C8, 7 as orthogonal codes corresponding to each subcarrier.
- C8, 1 (1, 1, 1, 1, 1, 1, 1, 1)
- C8, 2 (1, 1, 1, 1,-1,-1,-1, — 1)
- C8, 7 (1, —1, —1, 1, 1,-1,-1, 1).
- One of the features of the MC CDM system is that the data can be multiplexed and communicated by multiplying these three types of orthogonal codes using the same time and the same frequency.
- orthogonal codes C8, 1, C8, 2, C8, and 7 are all orthogonal codes with a period of 8, and data is separated between orthogonal codes by performing addition during one period. Can do.
- SFfreq in (a) of FIG. 22 indicates the period of the orthogonal code.
- FIG. 23A and 23B show the codes C, 8, 1, C '8, 2, C' 8, 7, C when MC-CDMA signals propagate in the air and are received by the radio receiver. “8, 1, C” 8, 2, C ”8 and 7.
- FIG. 23A shows the case where there is no frequency fluctuation in the period of the orthogonal code.
- Patent Document 2 and Non-Patent Document 1 describe one technique for improving characteristic deterioration due to the loss of orthogonality between the codes.
- there is a difference between downlink and uplink both of which are desired by using data after error correction or despreading to remove inter-code interference due to code multiplexing during MC-CDMA communication.
- the characteristics are improved by removing signals other than codes.
- Patent Document 1 Japanese Patent Application Laid-Open No. 2004-221702
- Patent Document 2 JP 2005-198223
- Non-Special Reference 1 "Downlink Transmission of Broadband OFCDM Systems-Part I: Hybrid Detectionbri, Zhou, ⁇ ⁇ ; Wang, J .; Sawahashi ⁇ M.Page (s): 718—729, IEEE Transactions on Communication (Vol.53, Issue4)
- the above-described technique has a problem in that the amount of calculation increases when demodulating a multicarrier signal and an MC-CDM signal having a large number of subcarriers.
- the amount of computation increases by the number of code multiplexes when removing inter-code interference during MCCDM.
- the present invention has been made in view of the above circumstances, and an object thereof is to provide a receiver and a receiving method that can reduce the amount of calculation when demodulating a signal received from a transmitter. It is in.
- the present invention has been made to solve the above problems, and a receiver according to an aspect of the present invention creates a replica signal that is a replica of a transmission signal based on the received signal.
- a replica signal creating unit an incoming wave removing unit that removes an incoming wave from a received signal using a replica signal every predetermined time zone, and a signal that the incoming wave removing unit removes an incoming wave every predetermined time zone
- a demodulator for demodulating the signal synthesized by the synthesizer.
- the incoming wave removal unit removes the incoming wave from the received signal every predetermined time zone from the received signal using the replica signal created by the replica signal creation unit, and the incoming wave is removed every predetermined time zone.
- the synthesized signal is synthesized by the synthesis unit, and the demodulation unit performs demodulation processing on the synthesized signal. This makes it possible to perform FFT processing on signals from which incoming waves have been removed. In addition, it is possible to perform despreading processing on signals with reduced frequency selectivity by removing incoming waves, and it is possible to eliminate inter-code interference with a calculation amount that is not related to the number of codes. .
- the incoming wave removal unit of the receiver includes a delayed wave replica generation unit that creates a replica of an incoming wave for each predetermined time zone, and the delay from a received signal.
- wave A subtracting unit that subtracts a replica of the incoming wave for each predetermined time period created by the replica generation unit.
- the delayed wave replica generation unit generates a delayed wave replica for each predetermined time zone, and the delayed signal replica is subtracted from the received signal force and synthesized by the synthesis unit. Therefore, the energy contained in the received signal can be used effectively without wasting it.
- the delayed wave replica generation unit of the receiver sets the predetermined time zone based on the number of identified incoming waves.
- a delayed wave replica can be created according to the number of incoming waves of the received signal.
- the delayed wave replica generation unit of the receiver sets the predetermined time zone based on the time of the identified incoming wave.
- an incoming wave replica can be created according to the time of the incoming wave of the received signal.
- the delayed wave replica generation unit of the receiver sets the predetermined time period based on the received power of the identified incoming wave.
- an incoming wave replica can be created according to the received power of the incoming wave of the received signal.
- the receiver includes a signal determination unit that performs error correction decoding based on a result of the demodulation process performed by the demodulation unit and determines a signal for each bit.
- the replica signal creation unit creates a replica signal that is a replica of the transmission signal based on the determination value calculated by the signal determination unit.
- a replica signal can be created based on the signal determination value.
- the signal determination unit of the receiver performs error correction decoding based on a result of the demodulation process performed by the demodulation unit, and calculates a log-likelihood for each bit to be calculated.
- the degree ratio is the judgment value.
- the replica signal can be generated based on the log likelihood ratio. it can.
- the receiver includes a propagation path noise power estimation unit that estimates a noise power estimation value, and the synthesis unit includes a channel impulse response estimation value and the noise noise.
- This MMSE filter determines the MMSE filter coefficient based on the estimated power value.
- the MMSE filter coefficient of the synthesis unit can be determined based on the channel impulse response estimation value and the noise power estimation value.
- the combining unit of the receiver includes the MMSE filter coefficient W represented by the formula (A) or the formula (B), or the MMSE represented by the formula (C). Filter coefficient W,
- mmmm Hamiltonian C is the number of multiplexed codes
- ⁇ " 2 is the estimated noise power
- i is the incoming wave rejection
- IT H is IT Roh, Milt - a draft).
- the MMSE filter coefficient used by the synthesizer is changed according to whether it is a power repetition demodulation that is the time of the first demodulation, so that more optimal MMS E filtering processing is performed. Can do.
- the propagation path noise power estimation unit of the receiver receives based on the replica signal generated by the replica signal generation unit and the channel impulse response estimation value.
- a reception signal replica generation unit that generates a replica signal of the signal, and a noise power estimation unit that estimates noise power by obtaining a difference between the replica signal generated by the reception signal replica generation unit and the reception signal. .
- the noise power is estimated by obtaining the difference between the replica signal created by the received signal replica generation unit and the received signal, the noise power estimation accuracy can be improved. .
- a replica signal creation unit that creates a replica signal that is a replica of the transmission signal of the receiver according to an aspect of the present invention based on the received signal, and a predetermined signal from the received signal using the replica signal
- An incoming wave removing unit that removes an incoming wave for each time zone, a propagation path that estimates an estimated noise power value, a noise power estimating unit, a replica error estimating unit that estimates the replica signal power replica error estimated value, and a received signal
- a filter coefficient is determined based on the channel impulse response estimated value estimated from the above, the noise power estimated value, and the replica error estimated value, and the incoming wave removing unit uses the filter coefficient for each predetermined time period.
- a synthesizing unit that synthesizes the signal from which the incoming wave is removed, and a demodulating unit that demodulates the signal synthesized by the synthesizing unit.
- FFT processing can be performed on a signal from which an incoming wave is removed, and despreading processing is performed on a signal whose frequency selectivity has been reduced by removing the incoming wave. This makes it possible to eliminate inter-code interference with a calculation amount that is not related to the number of codes. Further, it is possible to perform a least square error filtering process in consideration of a component due to an error of the replica signal.
- the synthesizing unit of the receiver estimates a channel impulse response estimated value for each predetermined time period based on the replica error estimated value.
- the combining unit of the receiver includes a buffer represented by the formula (D).
- Filter coefficient W (where m is a natural number, ⁇ " 2 is the noise power estimate and m N
- B is the number of arrival wave removal units, i, i 'are natural numbers less than or equal to the number of arrival wave removal units, and H "is the transfer function of the mth propagation path in the i-th arrival wave removal unit , H "H is H"
- the combining unit of the receiver may convert the H ′ ′ to the formula ( ⁇ ), m
- DFT [] indicates that the signal in [] is converted to the time domain force frequency domain, and h ⁇ h "is the target of processing in the i and i'th arriving wave cancellers. This is a delay profile obtained by extracting only the arriving waves, and is a replica error estimate).
- a receiver includes a replica signal creation unit that creates a replica signal that is a replica of a transmission signal based on the received signal, and a received signal using the replica signal.
- An arrival wave removal unit that removes an incoming wave for each predetermined time period, a propagation path noise power estimation unit that estimates a noise power estimation value, a channel impulse response estimation value estimated from a received signal, and the noise power estimation value And the inter-code interference estimated value estimated based on the number of code multiplexes, the filter coefficient is determined, and the incoming wave removal unit removes the incoming wave for each predetermined time zone using the filter coefficient.
- a synthesizing unit that synthesizes the synthesized signals, and a demodulating unit that demodulates the signals synthesized by the synthesizing unit In the receiver of the present invention, FFT processing can be performed on the signal from which the delayed wave has been removed, and despreading processing is performed on the signal having reduced frequency selectivity by removing the delayed wave. This makes it possible to eliminate inter-code interference with a calculation amount that is not related to the number of codes. In addition, during the second and subsequent iterations, interference components from other codes can be taken into account, and the characteristics can be improved.
- the combining unit of the receiver uses the filter coefficient W represented by the equation (F) (where m is a natural number, and C is a code multiplexing number). Yes, ⁇ ",
- H is the natural number less than or equal to the number, and the mth propagation path
- H 'H is the Mirto-Anne of H'
- H ' is the transfer function of the m-th propagation path in the i-th incoming wave removal part
- H "and H are H". , Hamiltonian of).
- the synthesis unit of the receiver includes a least square error filter, and uses a least square error filter coefficient as the filter coefficient.
- a replica signal creation process of creating a replica signal that is a replica of a transmission signal based on the reception signal, and a reception signal using the replica signal An incoming wave removal process for removing an incoming wave every predetermined time period from the received signal, a received signal composition process for synthesizing a signal from which the incoming wave is removed every predetermined time period in the incoming wave removal process, and the received signal A demodulation process is performed in which the signal synthesized in the synthesis process is demodulated.
- a reception method includes a replica signal generation process in which a replica signal that is a replica of a transmission signal is generated based on the received signal, and the replica signal is Received signal strength using Incoming wave elimination process that removes the incoming wave for each predetermined time zone, propagation path 'noise power estimation process to estimate noise power estimation value, and replica power error estimation value from the replica signal
- a filter coefficient is determined based on the replica error estimation process, the channel impulse response estimated value estimated from the received signal, the noise power estimated value, and the replica error estimated value, and the arrival coefficient is determined using the filter coefficient.
- a synthesis process for synthesizing a signal from which an incoming wave is removed every predetermined time period in a wave elimination process and a demodulation process for performing demodulation processing on the signal synthesized in the synthesis process are executed.
- a replica signal creation process of creating a replica signal that is a replica of a transmission signal based on the reception signal, and a reception signal using the replica signal Force An incoming wave elimination process that removes the incoming wave at predetermined time intervals, a propagation path noise noise estimation process that estimates the noise power estimate, a channel impulse response estimate estimated from the received signal, and the noise power
- a filter coefficient is determined based on the estimated value and the inter-code interference estimated value estimated based on the number of code multiplexes, and the filter coefficient is used to remove the incoming wave at a predetermined time zone in the incoming wave removal process.
- a synthesizing process for synthesizing the synthesized signals and a demodulating process for demodulating the signals synthesized in the synthesizing process are executed.
- an FFT can be used for each signal from which a delayed wave has been removed every predetermined time period. This makes it possible to perform FFT processing on the signal from which the delayed wave has been removed. In addition, it becomes possible to perform despreading processing on signals with reduced frequency selectivity by removing delayed waves, and it is possible to remove inter-code interference with a calculation amount that is not related to the number of codes. it can.
- FIG. 1 is a schematic block diagram showing a configuration of a wireless transmitter according to a first embodiment of the present invention.
- FIG. 2 is a diagram showing an example of a frame format according to the first embodiment of the present invention.
- FIG. 3 is a schematic block diagram showing a configuration of a radio receiver according to the first embodiment of the present invention.
- IV] is a diagram showing an example of the configuration of the MAP detection unit 23 (FIG. 3) according to the first embodiment of the present invention.
- FIG. 5 A flowchart showing an example of the operation of the wireless receiver according to the first embodiment of the present invention.
- FIG. 6 is a diagram showing a channel impulse response estimation value according to the first embodiment of the present invention.
- Fig. 7 is a diagram showing a channel innoc response estimation value in the soft canceller block unit 45-1 according to the first embodiment of the present invention.
- Fig. 8 is a diagram showing a channel innoc response estimation value in the soft canceller block unit 45-2 according to the first embodiment of the present invention.
- Fig. 9 is a diagram showing a channel innoc response estimation value in the soft canceller block unit 45-3 according to the first embodiment of the present invention.
- FIG. 10 is a diagram showing a channel innoc response estimated value and an MMSE filter unit in the initial processing according to the first embodiment of the present invention.
- Fig. 11 is a diagram showing a channel innoc response estimation value and an MMSE filter unit in the iterative processing according to the first embodiment of the present invention.
- FIG. 12 A diagram showing a configuration of a propagation path noise power estimation unit 22 (FIG. 3) according to the first embodiment of the present invention.
- FIG. 13 is a diagram illustrating a part of the configuration of the wireless receiver according to the second embodiment of the present invention.
- FIG. 14 is a diagram showing a part of the configuration of a wireless receiver according to the third embodiment of the present invention.
- FIG. 15 is a diagram illustrating an example of the configuration of the MAP detection unit 223 (FIG. 14) according to the third embodiment of the present invention.
- FIG. 16 is a diagram showing a part of the configuration of the wireless receiver according to the fourth embodiment of the present invention.
- ⁇ 17] A diagram showing an example of the configuration of the propagation path noise power estimation unit 322 (FIG. 16) according to the fourth embodiment of the present invention.
- FIG. 18 is a diagram illustrating an example of the configuration of a MAP detection unit 423 according to a fifth embodiment of the present invention.
- FIG. 19 is a diagram showing an example of the configuration of a MAP detection unit 23 according to a sixth embodiment of the present invention.
- FIG. 20 is a diagram illustrating a signal that reaches a wireless receiver from a wireless transmitter via a multipath environment.
- FIG. 21 is a diagram illustrating a state in which subcarriers are orthogonal to each other in signal transmission / reception using a multicarrier scheme and a state in which interference occurs between subcarriers due to ICI.
- FIG. 22 is a diagram showing the relationship between subcarriers and orthogonal codes corresponding to each subcarrier in the MC-CDMA system.
- FIG. 23A is a diagram showing a state when an MC-CDMA system signal propagates in the air and is received by a radio receiver.
- FIG. 23B is a diagram showing a state when an MC-CDMA system signal propagates in the air and is received by a radio receiver.
- GI removal unit 44 ''FFT unit, 45—1 to 45— 3 ⁇ Soft canceller block unit, 46, 46a- ⁇ ' MMSE filter unit , 47— 1 to 47— 4 'Log-likelihood ratio output unit for each code, 48 ⁇ ' despreading unit, 49 ⁇ Symbol dintariba unit, 50 ⁇ 'Soft decision output unit, 61 ⁇ 'Propagation path estimation unit, 62 ⁇ Preamble replica generation unit, 63 ⁇ ' Noise power estimation unit, 70 ⁇ 'MAC unit, 71 ⁇ ⁇ Filtering processing unit, 72 ⁇ ' DZA conversion unit, 73 ⁇ ⁇ 'Frequency converter, 74 ...' Transmitter antenna, 75 ...
- This embodiment describes a radio receiver that can obtain good characteristics even in the presence of ISI and ICI due to delayed waves exceeding the guard interval and inter-code interference due to channel frequency selectivity. To do.
- FIG. 1 is a schematic block diagram showing the configuration of the wireless transmitter according to the first embodiment of the present invention.
- This wireless transmitter consists of an SZP (Serial I Parallel) conversion unit 1, a signal processing unit for each code 2-1 to 2-4, and a DTCH (Data Traffic Channel) multiplexing unit 8 A PICH (Pilot Channel) multiplexing unit 9, a scrambling unit 10, an IFFT (Inverse Fast Fourier Transform) unit 11, and a GI insertion unit 12.
- Each code signal processing unit 2-1 to 2-4 includes an error correction coding unit 3, a bit interleaver unit 4, a modulation unit 5, a symbol interleaver unit 6, and a frequency one-time spreading unit 7.
- the information signal output from the MAC (Media Access Control) unit 70 is input to the SZP conversion unit 1, and the output of the serial / parallel conversion of the SZP conversion unit 1 is the signal processing unit 2 for each code.
- — 1 to 2 Input to 4
- the configuration of the signal processing unit for each code 2-2 to 2-4 is the same as that of the signal processing unit for each code 2-1. Therefore, as a representative example, the signal processing unit for each code 2-1 is described below. I will explain.
- the signal input to the code-by-code signal processing unit 2-1 is either error-coded by the error-correcting code unit 3, which is either turbo-coded, LDPC (Low Density Parity Check) coding, or convolutional coding.
- the output of the error correction coding unit 3 is processed by the bit interleaver unit 4 based on a drop in received power due to frequency selective fading! / In order to improve the occurrence of burst errors, the order of each bit is changed in an appropriate order and output.
- the output of the bit interleaver unit 4 is output from the modulation unit 5 by BPSK (Binary Phase Shift Keying), QPSK (Quadrature Phase Shift Keying), 16QAM (16 Quadrature Amplitude Modulation).
- Symbol modulation processing such as 64 quadrature amplitude modulation (64QAM) and 64QAM (64 quadrature amplitude modulation) is performed.
- the output of the modulation unit 5 is switched by the symbol interleaver unit 6 in an appropriate order for each symbol in order to improve the burst error.
- the output of the symbol interleaver unit 6 is spread by a predetermined spread code (channelization code) by the frequency one-time spread unit 7.
- a spreading code using an OVSF (Orthogonal Variable Spread Factor) code may be used as the spreading code.
- the wireless transmitter transmits a code-by-code signal processing unit 2-2 to 2-4 to the code multiplexing number C (C
- mux mux is a natural number greater than 1).
- the signal spread by the code is output as the output of the signal processing unit 2-1 for each code and multiplexed (added) by the DTCH multiplexing unit 8. Subsequently, the PICH multiplexing unit 9 inserts (time-multiplexes) the PICH used for propagation path estimation at a predetermined position.
- the signal is scrambled by the scrambling unit 10 with a scrambling code unique to the base station, and then the frequency time conversion is performed by the IFFT unit 11.
- the frequency time conversion is performed by the IFFT unit 11.
- filtering processing by filtering unit 71, digital analog conversion processing by DZ A (Digital I Analog) conversion unit 72, frequency conversion processing by frequency conversion unit 73, etc. were performed Thereafter, the signal is transmitted from the transmission antenna 74 to the wireless receiver as a transmission signal.
- bit interleaver unit 4 and the symbol interleaver unit 6 need not be arranged in the code-by-code signal processing units 2-2 to 2-4.
- FIG. 2 is a diagram showing an example of a frame format according to the first embodiment of the present invention.
- This figure shows the frame format of the multicarrier signal transmitted from the wireless transmitter to the wireless receiver.
- the horizontal axis represents time and the vertical axis represents received power.
- the PICH is placed before and after the frame and in the middle.
- the DTCH used for data transmission is placed in the first half and the second half of the frame, and C different extensions are used.
- a signal spread by a spread code is code-multiplexed.
- C 4
- FIG. 3 is a schematic block diagram showing the configuration of the radio receiver according to the first embodiment of the present invention.
- the radio receiver includes a symbol synchronization unit 21, a propagation path noise power estimation unit 22, a MAP detection unit 23, a MAP decoding unit for each code 24-1 to 24-4 (also referred to as a signal determination unit), and a replica signal generation unit 28.
- the replica signal generator 28 includes a P / S (Parallel / Serial) converter 39, the symbol generators for each code 29-1 to 29-4, the DTCH multiplexer 34, the PICH multiplexer 35, A scrambling part 36, an IFFT part 37, and a GI insertion part 38 are provided.
- P / S Parallel / Serial
- the replica signal creation unit 28 creates a replica signal that is a replica of the transmission signal based on the reception signal r (t). More specifically, the replica signal creation unit 28 creates a replica signal that is a replica of the transmission signal based on the log likelihood ratio calculated by the MAP decoding unit 26. Also, the per-code symbol generation unit 29-1 ⁇ 29-4 include a bit interleaver unit 30, a symbol generation unit 31, a symbol interleaver unit 32, and a frequency-time spreading unit 33. Each code MAP decoding unit 24-1 to 24-4 includes a bit interleaver 25, a MAP decoding unit 26, and an adding unit 27.
- the received signal received by the receiving antenna 75 is subjected to frequency conversion processing by a frequency conversion unit 76 and analog-digital conversion processing by an A / D (Analog / Digital) conversion unit 77, and then a digital reception signal r (t)
- the symbol synchronization unit 21 performs symbol synchronization as follows.
- the symbol synchronization unit 21 uses the correlation characteristics between the guard interval GI and the effective signal interval. Symbol synchronization is performed, and subsequent signal processing is performed based on the result.
- the propagation path estimation 'noise power estimation unit 22 uses PICH to estimate the channel impulse response and the noise power estimation value.
- PICH Physical Broadcast Channel Estimation
- a PICH replicated signal is created and the RLS algorithm is performed so that the square error of the absolute value is minimized, or the cross-correlation between the received signal and the PICH replica signal is calculated on the time axis.
- a method of creating a replica of PICH using the estimated channel impulse response from the received PICH and calculating the difference between these can be considered, but it is not limited to this.
- the channel impulse response and the noise power estimation value output from the propagation path and noise power estimation unit 22 use a MAP detection unit 23 (maximum posterior probability detector, maximum posterior probability (MAP) decoding method (described later). )) And used to calculate the log-likelihood ratio for each bit.
- MAP detection unit 23 maximum posterior probability detector, maximum posterior probability (MAP) decoding method (described later).
- the MAP detection unit 23 outputs the log likelihood ratio for each bit using the received signal, the channel impulse response, and the noise power estimation value.
- the log-likelihood ratio is a value indicating whether the received bit is most likely 0 or 1 and is calculated based on the bit error rate of the communication channel.
- four outputs are output to the MAP decoding / replica creation units 24-1 to 24-4 for each code, which is the log likelihood ratio of bits assigned to different spreading codes. Is output.
- the mux outputs are output to the MAP decoding units 24-1 to 24-4 for each code.
- the log likelihood ratio for each bit is output using the received signal and the replica signal obtained from the demodulation result, the channel impulse response, and the noise power estimation value.
- the MAP decoding units 24-1 to 24-4 perform a deinterleaving process on the input signal for each bit in the bit deinterleaver unit 25.
- the deinterleaving process is the reverse process of the interleaving process, and the order change by the interleaving process is restored.
- the MAP decoding unit 26 performs MAP decoding processing on the output of the bit dintaraver unit 25.
- the MAP decoding unit 26 is a soft decision output unit 5 of the MAP detection unit 23. Based on the result of soft decision by 0 (Fig. 4, described later), error correction decoding is performed and the log likelihood ratio for each bit is calculated.
- the MAP decoding process does not perform hard decision during normal error correction decoding such as turbo decoding, LDPC decoding, and Viterbi decoding, and includes log likelihood ratio including information bits and parity bits. This is a method for outputting a soft decision result. In other words, hard decision is made based only on 0 and 1 received signals, while soft decision is made based on the information (soft decision information) of how accurate it is!
- the difference 2 between the input of the MAP decoding unit 26 and the output of the MAP decoding unit 26 is calculated by the adding unit 27 and output to the replica signal creating unit 28.
- the input to the replica signal creation unit 28 is input to the bit interleaver unit 30, and the bit interleaver unit 30 outputs ⁇ 2 for each bit.
- the output of the bit interleaver unit 30 is subjected to symbol modulation processing in the symbol generation unit 31 with the same modulation scheme (BPSK, QPSK, 16QAM, 64QAM, etc.) as the radio transmitter in consideration of the size of ⁇ 2.
- the output of the symbol generator 31 is switched by the symbol interleaver 32 for each symbol, and the output of the symbol interleaver 32 is spread with a predetermined spreading code (channelization code) by the frequency-time spreader 33.
- the radio receiver is provided with a MAP decoding unit for each code and a symbol generation unit for each code, as many as the code multiplexing number C (C is a natural number of 1 or more).
- C 4
- the Signals spread with different spreading codes are also output as replica generation units 29-1 to 29-4 for each code and multiplexed (added) by the DTCH multiplexing unit 34.
- the PICH multiplexing unit 35 the PICH used for propagation path estimation or the like is inserted (time multiplexed) at a predetermined position.
- frequency time conversion is performed in the IFFT unit 37, and GI insertion is performed in the GI insertion unit 38, and then the MAP detection unit 23 And used for signal processing during repetition.
- the output of the MAP decoding unit 26 is input to the PZS conversion unit 39, subjected to parallel-serial conversion, and then output to the MAC unit (not shown) as a demodulation result. .
- FIG. 4 shows an example of the configuration of the MAP detection unit 23 (FIG. 3) according to the first embodiment of the present invention. It is a figure.
- the MAP detection unit 23 includes a soft canceller block unit 45-1 to 45-3 (also referred to as an incoming wave removal unit), an MMSE (Minimum Mean Square Error) filter unit 46 (also referred to as a synthesis unit), a code
- MMSE Minimum Mean Square Error filter unit 46
- Each log-likelihood ratio output unit 47-1 to 47-4 also called demodulator
- the soft canceller block units 45-1 to 45-3 each include a delayed wave replica generation unit 41, an addition unit 42 (also referred to as a subtraction unit), a GI removal unit 43, and an FFT unit 44.
- the soft canceller block units 45-1 to 45-3 remove the delayed wave at every predetermined time zone using the replica signal created by the replica signal creation unit 28 using the received signal r (t) force.
- the delayed wave replica generation unit 41 receives the channel impulse response estimation value, which is a propagation path estimation value estimated from the received signal r (t), and the replica signal generated by the replica signal generation unit 28 (Fig. 3) (t ), A delayed wave replica for each predetermined time zone is created.
- the adder 42 subtracts the delayed wave replica for each predetermined time zone created by the delayed wave replica generating unit 41 from the received signal! :( t).
- the log likelihood ratio output units 47-1 to 47-4 for each code are provided with a despreading unit 48, a symbol dinaver unit 49, and a soft decision output unit 50, respectively.
- the received signal r (t) input to the MAP detection unit 23 is obtained based on the replica signal s "(t) input to the MAP detection unit 23 and the channel impulse response estimated values h to (t).
- the difference from the output of the generated delayed wave replica generation unit 41 is calculated by the addition unit 42 and output to the GI removal unit 43.
- the guard interval GI is removed by the GI removal unit 43 and output to the FFT unit 44.
- the FFT unit 44 performs time-frequency conversion on the input signal to obtain signals R to i.
- the MAP detection unit 23 is provided with a soft canceller block unit B (B is a natural number of 1 or more) blocks. Note that i is a natural number and l ⁇ i ⁇ B.
- the MMSE filter unit 46 synthesizes the signal from which the delayed wave is removed for each predetermined time zone by the soft canceller block units 45-1 to 45-3. Specifically, the MMSE filtering process is performed in the MMSE filter unit 46 using the outputs R to i of the soft canceller block unit, the channel impulse response estimation value, and the noise power estimation value, and the signal Y, is obtained.
- the despreading unit 48 performs despreading processing using each spreading code.
- the symbol deinterleaver 49 replaces the output of the despreader 48 for each symbol.
- the soft decision output unit 50 performs soft decision on the signal synthesized by the MMSE filter unit 46.
- the soft decision output unit 50 outputs a log-likelihood ratio ⁇ 1 for each bit as a soft decision result with respect to the symbol deinterleave output.
- the soft decision output unit 50 calculates the log likelihood ratio ⁇ 1 by using the following equations (1) to (3). That is, if the output of the ⁇ -th symbol of symbol dinger section 49 is ⁇ , soft decision result ⁇ 1 at the time of QPSK modulation can be expressed by the following equations (1) and (2).
- R [] indicates the real part in Katsuko
- Im [] indicates the imaginary part in Katsuko
- ⁇ ( ⁇ ) is the reference symbol (amplitude of the pilot signal) in the ⁇ symbol.
- FIG. 5 is a flowchart showing an example of the operation of the radio receiver according to the first embodiment of the present invention.
- the MAP detection unit 23 determines whether or not the first operating force is good (step Sl). If it is determined in step S1 that the operation is the first operation, the GI removal unit 43 removes the guard interval GI from the received signal r (t) (step S2).
- the FFT unit 44 performs FFT processing (time frequency conversion processing) (step S3).
- the MMSE filter unit 46 performs a normal MMSE filter process (step S4).
- the despreading unit 48 performs a despreading process (step S5).
- the symbol dinuller unit 49 performs symbol dingeriba processing (step S6).
- the soft decision output unit 50 performs soft decision bit output processing (step S7).
- the bit dintariba unit 25 performs a bit dintariba process (step S8).
- the MAP decoding unit 26 performs a MAP decoding process (step S9).
- bit interleaver unit 30 uses the log result 2 for the C code and the logarithmic likelihood.
- step Sl l Bit interleave the degree ratio
- the symbol generation unit 31 creates a modulated signal replica
- the symbol interleaver unit 32 performs symbol interleaver processing (step S13).
- the frequency-time spreading unit 33 performs spreading processing using a predetermined spreading code (step S14).
- step S15 perform CH multiplexing
- step S16 performs PICH multiplexing (step by step).
- step S16 performs PICH multiplexing (step by step).
- step S17 performs scrambling processing
- step S17 performs IFFT processing
- step S19 inserts a guard interval GI (step S19). The signal with the GI inserted in step S19 is used as a replica signal and used during repeated demodulation.
- step S1 If it is determined in step S1 that it is a repetition time, that is, it is not the first operation, the soft canceller block units 45-1 to 45-3 remove other than the predetermined delay wave for each block. (Step S20). Then, the GI removal unit 43 performs GI removal processing (step S21). Next, the FFT unit 44 performs FFT processing (step S22). After the processing of steps S20 to S22 described above is performed for B (B is a natural number) blocks, the MMSE filter unit 46 synthesizes the output signal from the B block using the MMSE filter according to the least square error criterion. In other words, M MSE filter processing is performed (step 23). After step 23, the process proceeds to step S5 and the same process as the initial process is performed.
- Steps S1 to S9 and S11 to S23 are repeated until it is determined in step S10 that the above-described processing has been repeated a predetermined number of times.
- the delayed wave replica generation unit 41 generates h and performs a convolution operation with the replica signal s "(t) to obtain the received signal !: (t) This is the output of the adder 42 (where i is a natural number with i ⁇ B).
- FIG. 6 is a diagram showing a channel innol response estimated value according to the first embodiment of the present invention.
- the channel impulse response estimation value obtained from the propagation path * noise power estimation unit 22 is obtained.
- the case where 6-path channel impulse response estimation values pl to p6 are obtained will be described.
- the horizontal axis represents time
- the vertical axis represents received power.
- soft canceller block 45-1 to 45-3 6-path delayed waves are decomposed into 3 delayed waves of 2 paths each.
- FIG. 7 is a diagram showing channel impulse response estimation values in the soft canceller block unit 45-1 according to the first embodiment of the present invention.
- Cerablock 45-1 defines h (t) as the third path (p3), the fourth path (p4), the fifth path (p5), and the sixth path (p6) surrounded by dotted lines.
- the delayed wave replica generation unit 41 generates the delayed wave replica.
- the output of the delayed wave replica generation unit 41 is a convolution operation of the h (t) and s "(t), and the output of the addition unit 42 is obtained from the received signal r (t) from the h (t ) And s "(t) are subtracted.
- the output of the adder 42 can be considered as a signal received via a propagation path represented by (h (t) -h (t)).
- FIG. 8 is a diagram showing channel impulse response estimation values in the soft canceller block unit 45-2 according to the first embodiment of the present invention. As shown in Fig. 8, first, in the soft canceller block 45-2, the first path (pi), second path (p2), fifth path (p5), and sixth path (p6) surrounded by dotted lines ) Is defined as h (t) and is generated by the delayed wave replica generation unit 41.
- the output of the delayed wave replica generation unit 41 is a convolution operation of h (t) and s "(t).
- the output of the adder 42 is a convolution of h (t) and s "(t) from the received signal r (t).
- FIG. 9 is a diagram showing a channel impulse response estimation value in the soft canceller block unit 45-3 according to the first embodiment of the present invention.
- the first path (pi), second path (p2), third path (p3), fourth path (p4) surrounded by dotted lines ) Is defined as h (t) and is generated by the delayed wave replica generation unit 41.
- the output of the delayed wave replica generation unit 41 is a convolution operation of h (t) and s "(t).
- the output of the adder 42 is a convolution of h (t) and s "(t) from the received signal r (t).
- the soft canceller block units 45-1 to 45-3 set a predetermined time zone based on the number of identified delayed waves. That is, the case has been described where the replica signal to be created and subtracted is changed for each soft canceller block unit 45-1 to 45-3 based on the number of identified delayed waves based on the channel impulse response estimation value.
- the soft canceller block units 45-1 to 45-3 set a predetermined time zone based on the identified delayed wave time.
- the arrival time of the delayed wave is divided into B, and it is determined which soft canceller block unit performs processing according to which time zone the delayed wave has reached, that is, based on the time of the identified delayed wave.
- the replica signal to be generated and subtracted may be changed for each soft canceller block unit.
- the soft canceller block units 45-1 to 45-3 may set a predetermined time zone based on the received power of the identified delayed wave. In other words, all received signals are divided into B so that the received signals included in the delay wave are almost constant in the order of arrival time, and based on this, which soft canceller block unit is to be processed is determined. Depending on the received power of the delayed delay, the replica signal to be created and subtracted for each soft canceller block may be changed.
- FIGs. 10 (a) to 10 (c) are diagrams showing channel impulse response estimation values and the MMSE filter unit in the initial processing according to the first embodiment of the present invention.
- the operation of the MMSE filter unit 46 shown in FIG. 4 and steps S4 and S23 shown in FIG. 5 will be described.
- the operation of the first MMSE filter unit 46 will be described.
- the received signal R can be expressed by the following equation (4).
- the transfer function of the estimated propagation path is shown, and assuming that only a delayed wave within the guard interval GI exists, it can be represented by a diagonal matrix of Nc * Nc.
- Na Nc indicates the number of subcarriers of spread—OFCDM. In other words, it can be expressed as the following equation (5).
- S represents a transmission symbol, and can be represented by a vector of Nc * 1, as shown in the following equation (6).
- the received signal R and the noise component N can be represented by a vector of Nc * 1, as shown in the following formulas (7) and (8).
- T used as a subscript represents a transposed matrix.
- the output Y of the MMSE filter unit 46 is expressed by the following equation (9 ) Can be represented as a vector of Nc * 1
- the MMSE filter unit 46 determines the MMSE filter coefficient W based on the channel impulse response estimated value and the noise power estimated value.
- the MMSE filter coefficient W can be represented by a diagonal matrix of Nc * Nc as shown in the following equation (10).
- each element of the MMSE filter coefficient W is expressed by the following equation (
- [0082] represents an estimated value of noise power.
- the subscript H indicates Hamiltonian (conjugate transpose).
- each element of the above MMSE filter coefficient W can be expressed by the following equation (12) assuming that the orthogonality between codes is maintained during spreading in the time direction.
- FIG. 10 (a) shows the channel impulse responses pl to p6 shown in FIG. (B) in FIG. 10 shows a transfer function in which the channel impulse responses pl to p6 are expressed on the frequency axis.
- the horizontal axis indicates the frequency and the vertical axis indicates the power. It can be seen that the frequency selectivity is high (the power fluctuation in the frequency axis direction is large) in the initial processing. This state means that, as mentioned earlier, in MC-CDMA, the orthogonality is lost between codes and inter-code interference occurs.
- the replica signal used in the i-th soft canceller block unit 45-i can be expressed as the following equation (13).
- h is a delay profile obtained by extracting only the delayed wave to be processed in the i-th soft canceller block unit 45-i.
- S (t) is obtained by the previous MAP decoding. It is a replica signal calculated based on the log likelihood ratio ⁇ 2.
- ⁇ includes an error signal due to replica uncertainty and a thermal noise component.
- the output ⁇ of the MMSE filter unit 46 can be expressed by the following equation (15).
- the sub-matrix of the MMSE filter coefficient is It can be represented by a diagonal matrix as shown in Equation (16).
- the input signal to the MMSE filter unit 46 is assumed to have low frequency selectivity as described later, and to be in a state close to flat fading, and there is no inter-code interference at the time of code multiplexing. Then, each element can be expressed by the following formula (17).
- ⁇ ' is the transmission of the mth propagation path in the i'th soft canceller block
- H H 's no Milt-Anne.
- FIG. 11 shows a state in which signals that have passed through the propagation paths shown in FIGS. 7 to 9 are input to the MMSE filter unit 46 based on the MMSE filter coefficients in the iterative processing.
- the number B of the soft canceller block is set to 3!
- the MMSE filter unit 46 uses the MMS E filter coefficient W expressed by equation (11) or (12) at the time of initial demodulation, and uses the MMSE filter coefficient w, expressed by equation (17) at the time of repeated demodulation.
- FIG. 11 As with (a) in Fig. 10, (a) in Fig. 11, (c) in Fig. 11, and (e) in Fig. 11 represent the channel impulse responses pi to ⁇ 6 shown in Figs. Is shown. (B) in FIG. 11, (d) in FIG. 11, and (f) in FIG. 11 show the transfer functions in which the channel impulse responses pl to p6 are expressed on the frequency axis.
- the horizontal axis indicates frequency
- the vertical axis indicates power. It can be seen that the frequency selectivity is low (the power fluctuation in the frequency axis direction is small) during the iterative processing. As described above, this state means that in MC-CDMA, orthogonality is maintained between codes, and inter-code interference hardly occurs.
- FIG. 12 is a diagram showing a configuration of the propagation path * noise power estimation unit 22 (FIG. 3) according to the first embodiment of the present invention.
- the propagation path / noise power estimation unit 22 includes a propagation path estimation unit 61, a preample replica generation unit 62, and a noise power estimation unit 63.
- the propagation path estimation unit 61 estimates the channel impulse response using the PICH included in the received signal.
- the preamble replica generation unit 62 uses the channel impulse response estimation value obtained by the propagation path estimation unit 61 and the PICH signal waveform that is known information. And create a PICH replica signal.
- the noise power estimation unit 63 estimates the noise power by taking the difference between the PICH part included in the received signal and the PICH replica signal output from the preamble replica generation unit 62.
- propagation path estimation method in the propagation path estimation unit 61 various methods such as a method of deriving based on the least square error norm using a RLS algorithm or a method using frequency correlation can be used. .
- the received signal r (t) force is also generated for each predetermined time zone using the replica signal generated by the replica signal generating unit 28.
- the MMS E filter unit 46 synthesizes the signal from which the delayed wave is removed by the generator 41 and the delayed wave is removed for each predetermined time zone, and the soft decision output unit 50 performs the soft decision on the synthesized signal.
- FFT processing can be performed on the signal from which the delayed wave has been removed.
- FIG. 13 is a diagram showing a part of the configuration of the wireless receiver according to the second embodiment of the present invention.
- the configuration of the radio receiver is almost the same as the configuration of the radio receiver according to the first embodiment (Fig. 3), but the portions corresponding to the MAP decoding units 24-1 to 24-4 for each code in Fig. 3 are different.
- the configuration of the radio receiver is almost the same as the configuration of the radio receiver according to the first embodiment (Fig. 3), but the portions corresponding to the MAP decoding units 24-1 to 24-4 for each code in Fig. 3 are different.
- the log-likelihood specific power for each bit output from the MAP detection unit 23 is input to the P / S conversion unit 132, subjected to the normal serial conversion, and then subjected to the din-tarbation for each bit in the bit dinger unit 125.
- the MAP decoding unit 126 performs MAP decoding processing on the output of the bit dintaraver unit 125.
- the MAP decoding process is a method of outputting a log likelihood ratio including information bits and parity bits without performing hard decision in normal error correction decoding such as turbo decoding, LDPC decoding, and Viterbi decoding. It is.
- the replica signal generation unit 128 includes a bit interleaver unit 130, a symbol generation unit 131, an SZP conversion unit 134, a symbol-by-code symbol interleaver spreading unit 13 5-1 to 135-4, a DTCH multiplexing unit 34, a PICH multiplexing unit 35, and scrambling.
- the symbol interleaver spreading unit 135-1 to 135-4 for each code includes a symbol interleaver unit 132 and a frequency-time spreading unit 133.
- the input to the replica signal creation unit 128 is input to the bit interleaver unit 130, and the bit interleaver unit 130 switches ⁇ 2 for each bit and outputs it.
- the output of the bit interleaver unit 130 is subjected to symbol modulation processing such as BPSK, QPSK, 16 QAM, and 64QAM according to the size of 2 in the symbol generation unit 131, and the output of the symbol generation unit 131 is output to the SZP conversion unit 134.
- symbol modulation processing such as BPSK, QPSK, 16 QAM, and 64QAM
- the signal input to the symbol interleaver for each code 'spreading unit 135-1 to 135-4 is input to the symbol interleaver unit 132, the order is changed for each symbol, and then the frequency one time spreading unit Entered in 133.
- the frequency one-time spreading unit 133 performs spreading with a predetermined spreading code (channelization code), and then outputs it to the DTCH multiplexing unit 34.
- the subsequent operation is the same as that of the first embodiment, and detailed description thereof is omitted.
- the radio receiver of the second embodiment of the present invention it is possible to remove a delayed wave exceeding the guard interval GI by performing iterative decoding using the configuration of the radio receiver shown in FIG. At the same time, the influence of inter-code interference can be removed.
- both the bit interleaver unit 130, the bit ding interleaver unit 125, the symbol interleaver unit 132, and the symbol ding interleaver unit 49 are arranged.
- only the bit interleaver unit 130 and the bit ding interleaver unit 125 may be used alone, or only the symbol interleaver unit 132 and the symbol ding interleaver unit 49 may be used.
- all of the bit interleaver unit 130, the bit ding interleaver unit 125, the symbol interleaver unit 132, and the symbol ding interleaver unit 49 may not be arranged. This is the same as in the first embodiment. [0109] (Third embodiment)
- diffusion processing is performed! Explain how to receive multi-carrier signals.
- FIG. 14 is a diagram showing a part of the configuration of the wireless receiver according to the third embodiment of the present invention.
- the configuration of the radio receiver is almost the same as the configuration of the radio receiver of the second embodiment (FIG. 13), but the MAP detection unit 23, replica signal generation unit 128, and replica signal generation unit 128 in FIG.
- the included symbol interleaver / spreader 135-1 to 135-4, the symbol interleaver 132, the frequency-time spreader 133, and the DTCH multiplexer 34 are different.
- FIG. 13 The included symbol interleaver / spreader 135-1 to 135-4, the symbol interleaver 132, the frequency-time spreader 133, and the DTCH multiplexer 34 are different.
- MAP decoding processing is a method of outputting a log likelihood ratio including information bits and parity bits without performing hard decision during normal error correction decoding such as turbo decoding, LDPC decoding, and Viterbi decoding. It is.
- the difference 2 between the input and output of the MAP decoding unit 126 is calculated by the adding unit 127 and output to the replicated signal generating unit 228.
- the input to the replica signal generation unit 228 is output to the bit interleaver unit 130, and the bit interleaver unit 130 outputs ⁇ 2 by exchanging for each bit.
- the output of the bit interleaver unit 130 is subjected to symbol modulation processing such as BPSK, QPSK, 16QAM, and 64QAM according to the size of 2 in the symbol generation unit 131, and the output of the symbol generation unit 131 is output to the symbol interleaver unit 232 After being switched for each symbol, it is output to the PICH multiplexing unit 35. Thereafter, the same operation as that of the wireless receiver according to the first embodiment (FIG. 3) is performed, and thus detailed description thereof is omitted.
- FIG. 15 is a diagram showing an example of the configuration of the MAP detection unit 223 (FIG. 14) according to the third embodiment of the present invention.
- the configuration of the MAP detection unit 223 is almost the same as that of the MAP detection unit 223 (FIG. 4) according to the first embodiment, but the log likelihood ratio output unit for each code in FIG. 47-4, despreading section 48, symbol dinger section 49, and soft decision output section 50 are different.
- the MAP detection unit 223 includes B soft canceller block units 45-1 to 45-B (here,
- the E filter unit 46, the symbol dingeriba unit 249 that replaces the output of the MMSE filter unit 46 for each symbol, and the soft that outputs the log likelihood ratio for each bit of the symbol dingerive output A judgment output unit 250 is provided.
- the soft canceller block unit and the MMSE filter unit 46 are the same as those in the first embodiment (FIG. 4).
- the radio receiver of this embodiment uses a different noise power estimation method compared to the first embodiment.
- FIG. 16 is a diagram showing a part of the configuration of the wireless receiver according to the fourth embodiment of the present invention.
- the configuration of the wireless receiver is almost the same as that of the wireless receiver according to the first embodiment (FIG. 3), but the propagation path and noise power estimation unit 22 in FIG. 3 are different.
- the input signal only the received signal r (t) is input in the propagation path * noise power estimation unit 22 shown in FIG. 3, whereas the received signal is received in the propagation path 'noise power estimation unit 322 in FIG. !: (t) and the replica signal s "(t) that is the output of the replica signal creation unit 28 are input.
- FIG. 17 is a diagram illustrating an example of the configuration of the propagation path * noise power estimation unit 322 (FIG. 16) according to the fourth embodiment of the present invention.
- the propagation path noise power estimation unit 322 includes a propagation path estimation unit 61, a received signal replica generation unit 362, and a noise power estimation unit 363.
- the propagation path estimation unit 61 estimates the channel impulse response using the PICH included in the received signal.
- Reception signal replica generation section 362 generates a replica of reception signal r (t) based on the replica signal generated by replica signal generation section 28 and the channel impulse response estimated value. Specifically, the received signal replica generation unit 362 outputs the channel impulse response estimation value h ′ (t) obtained by the propagation path estimation unit 61, the PICH signal waveform that is known information, and the output of the MAP decoding unit 26. The PICH replica signal and the DTCH replica signal are created using the replica signal s ′ (t) obtained from the log-likelihood ratio ⁇ 2 for which the power is also obtained.
- the noise power estimator 363 uses the replica signal generated by the received signal replica generator 362 [0117] [Equation 27]
- the noise power is estimated by obtaining the difference between the received signal r (t) and the received signal r (t).
- the noise power estimation value calculated by the noise power estimation unit 363 can include both the error of the MAP decoding result and the Gaussian noise component, and the MMSE filter coefficient in the MMSE filter unit 46 can be obtained more appropriately. It is done.
- the configuration of the wireless receiver according to the present embodiment can also be applied to the radio receiver according to the second or third embodiment.
- the wireless receiver of the fifth embodiment differs from the first embodiment in the configuration of the MAP detection unit in the configuration of the wireless receiver (FIG. 3).
- the MMSE filter coefficient used in the MMSE filter unit 46 (FIG. 4) in the first embodiment assumes that a replica signal is generated with high accuracy, and uses only the thermal noise component in Equation (14). Yes.
- MMSE filtering processing is performed in consideration of an error due to uncertainty of a replica signal.
- FIG. 18 is a diagram illustrating an example of the configuration of the MAP detection unit 423 according to the fifth embodiment of the present invention.
- the configuration of the MAP detection unit 423 is substantially the same as that of the MAP detection unit 23 (FIG. 4) in the first embodiment, but the replica signal power replica error estimation value input to the MAP detection unit 423 is estimated.
- An error estimation unit 478 is provided, and its replica error estimation value is output together with the output of the soft canceller block units 45-1 to 45-3, the channel impulse response estimation value, and the noise power estimation value, as in the first embodiment. Are input to the MMSE filter unit 446.
- the MMSE filter unit 446 estimates an impulse response estimated value for each of the soft canceller block units 45-1 to 45-3 based on the input channel impulse response estimated value and replica error estimated value, and the soft canceller block unit 45— MMSE filter coefficients are determined based on the impulse response estimation value and noise power estimation value for each of 1 to 45-3, and the soft canceller block unit 45-1 to 45-3 The output is synthesized.
- the replica error estimation value 2 P is calculated by the following equation (18) based on the input replica signal s "(t).
- the estimated replica error estimated value P is a soft canceller block unit 45-1 to 45.
- the output of 3 and the channel impulse response estimation value and noise power estimation value are input to the MMSE filter unit 446.
- the MMSE filter unit 446 calculates the channel impulse response estimate PT for each of the soft canceller block units 45-1 to 45-3.
- DFT [] indicates that the signal in [] is converted to time domain force frequency domain.
- H which is a delay profile obtained by extracting only the delayed wave to be processed in the i-th soft canceller block unit 45-i, is expressed by the following equation (21).
- h represents the channel impulse response estimation value input to the MAP detection unit 423, and is processed in the i-th soft canceller block unit 45-i as in the first embodiment.
- This is a delay profile obtained by extracting only the delay wave.
- H is the natural number less than or equal to the number, and the mth,
- ⁇ ⁇ is the Hamiltonian of IT
- IT is the transfer function of the mth propagation path in the i'th soft canceller block 45-1 to 45-3
- ITH is PT Milton-An.
- the replica signal s "(t) which is a replica of the transmission signal, is generated by the replica signal generating unit 28 based on the received signal !: (t). Then, using the replica signal s "(t), the received signal r (t) force is removed by the soft canceller block 45-1 to 45-3 for each predetermined time period, and the noise power estimate ⁇ ' 2 propagation path' noise power estimation
- Section 22 estimates the replica error estimate from the replica signal s "(t), and the channel impulse response estimate H '' estimated from the replica error estimate from the received signal r (t) MMSE filter coefficient (filter) based on the estimated noise power ⁇ ' 2 and replica error estimate ⁇
- MMSE filter unit 446 determines W (refer to equation (22)), and the MMS,
- the MMSE filter coefficient used at the time of the first demodulation is the same as the equation (11) or the equation (12) in the first embodiment.
- the MMSE filtering process according to the fifth embodiment can be applied to the radio receivers according to the second to fourth embodiments.
- FIG. 19 is a diagram showing an example of the configuration of the MAP detection unit 23 according to the sixth embodiment of the present invention.
- the radio receiver according to the present embodiment is different in that an MMSE filter unit 46a is provided instead of the MMSE filter unit 46 of the radio receiver according to the first embodiment (see FIG. 4).
- FIG. 4 Note that parts having the same configuration as that of the wireless receiver according to the first embodiment (FIG. 4) are denoted by the same reference numerals in the sixth embodiment (FIG. 19). Their explanation is omitted.
- the incoming signal is divided into blocks, and the frequency selectivity in each block is made close to flat, so that MC-CDM using frequency-direction spreading reduces orthogonality between codes. Can be maintained, and interference between codes can be suppressed.
- the MMSE filter unit 46a uses the MMSE filter coefficient W expressed by the following equation (23) at the second and subsequent iterations.
- [0139] represents an interference component (also referred to as an inter-code interference estimated value) from another code at the time of code multiplexing.
- Equation (23) m is a natural number, C is a code multiplex number, and ⁇ "mux N
- IT 45 is the transfer function of the m-th propagation path in 45-3, and IT ⁇ is IT Hamiltonian m m
- H 'H is the Hamiltonian of H'.
- the replica signal creation unit 28 creates the replica signal s "(t), which is a replica of the transmission signal, based on the received signal !: (t). , replica signal s '(t) the delayed wave soft cancellation Love lock unit 45- 1 45- 3 to remove each zone the received signal, r (t) forces a predetermined time using a noise power estimated value sigma' 2 Propagation path 'noise power estimator 22
- MMSE filter coefficient W (see Equation (23)) is determined based on
- the soft canceller block 45— 1 45— 3 is
- the signal from which the delayed wave has been removed is synthesized by the MMSE filter unit 46a, and the soft decision output unit 50 performs the soft decision on the signal synthesized by the MMSE filter unit 46a.
- MMSE filter coefficient W used in the first demodulation is the same as in the first embodiment.
- MMSE filter according to the sixth embodiment is also applicable to the radio receivers according to the second to fifth embodiments.
- the amount of calculation is reduced even when demodulating a multicarrier signal having a large number of subcarriers by using FFT.
- FFT Fast Fourier transform
- the wireless receiver may be controlled by recording a program for recording on a computer-readable recording medium, causing the computer system to read and execute the program recorded on the recording medium.
- the “computer system” here includes the OS and hardware such as peripheral devices.
- Computer-readable recording medium refers to a storage device such as a flexible disk, a magneto-optical disk, a portable medium such as ROM, CD-ROM, or a hard disk incorporated in a computer system.
- a “computer-readable recording medium” means that a program is dynamically held for a short time, like a communication line when a program is transmitted via a network such as the Internet or a communication line such as a telephone line. And those that hold a program for a certain period of time, such as volatile memory inside a computer system as a server or client in that case.
- the program may be for realizing a part of the functions described above, or may be a program capable of realizing the functions described above in combination with a program already recorded in the computer system. .
Abstract
Description
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PCT/JP2007/060429 WO2007136056A1 (ja) | 2006-05-22 | 2007-05-22 | 受信機及び受信方法 |
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EP (1) | EP2023518A1 (ja) |
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WO (1) | WO2007136056A1 (ja) |
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WO2009031649A1 (ja) * | 2007-09-05 | 2009-03-12 | Sharp Kabushiki Kaisha | 受信機及び受信方法 |
JP2009206603A (ja) * | 2008-02-26 | 2009-09-10 | Sony Corp | 通信装置、ノイズ除去方法、およびプログラム |
WO2009133816A1 (ja) * | 2008-04-30 | 2009-11-05 | シャープ株式会社 | 通信システム、受信装置及び通信方法 |
JP2010178273A (ja) * | 2009-02-02 | 2010-08-12 | Sharp Corp | 受信装置及び受信方法 |
WO2011052429A1 (ja) | 2009-10-27 | 2011-05-05 | シャープ株式会社 | 受信装置、受信方法、通信システムおよび通信方法 |
JP2011234282A (ja) * | 2010-04-30 | 2011-11-17 | Sharp Corp | 通信システム、送信装置、受信装置、プログラム、及びプロセッサ |
JP2013243664A (ja) * | 2012-05-22 | 2013-12-05 | Aeroflex Ltd | ノイズ電力推定方法 |
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JP5030279B2 (ja) * | 2006-05-19 | 2012-09-19 | パナソニック株式会社 | 無線通信装置及び無線通信方法 |
JP2011188206A (ja) * | 2010-03-08 | 2011-09-22 | Sharp Corp | 受信装置、受信方法、受信プログラム、及びプロセッサ |
CN104025458A (zh) * | 2012-03-26 | 2014-09-03 | 三菱电机株式会社 | 接收机、通信装置以及通信方法 |
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JP2009272725A (ja) * | 2008-04-30 | 2009-11-19 | Sharp Corp | 通信システム、受信装置及び通信方法 |
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US8874985B2 (en) | 2010-04-30 | 2014-10-28 | Sharp Kabushiki Kaisha | Communication system, transmission device, reception device, program, and processor |
JP2013243664A (ja) * | 2012-05-22 | 2013-12-05 | Aeroflex Ltd | ノイズ電力推定方法 |
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US20090141834A1 (en) | 2009-06-04 |
EP2023518A1 (en) | 2009-02-11 |
JPWO2007136056A1 (ja) | 2009-10-01 |
JP4963703B2 (ja) | 2012-06-27 |
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