WO2007119280A1 - Mimo受信装置および受信方法 - Google Patents
Mimo受信装置および受信方法 Download PDFInfo
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- WO2007119280A1 WO2007119280A1 PCT/JP2007/051754 JP2007051754W WO2007119280A1 WO 2007119280 A1 WO2007119280 A1 WO 2007119280A1 JP 2007051754 W JP2007051754 W JP 2007051754W WO 2007119280 A1 WO2007119280 A1 WO 2007119280A1
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B7/00—Radio transmission systems, i.e. using radiation field
- H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
- H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
- H04B7/08—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the receiving station
- H04B7/0837—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the receiving station using pre-detection combining
- H04B7/0842—Weighted combining
- H04B7/0845—Weighted combining per branch equalization, e.g. by an FIR-filter or RAKE receiver per antenna branch
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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
-
- 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
- H04B1/76—Pilot transmitters or receivers for control of transmission or for equalising
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B7/00—Radio transmission systems, i.e. using radiation field
- H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
- H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
- H04B7/0413—MIMO systems
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04J—MULTIPLEX COMMUNICATION
- H04J99/00—Subject matter not provided for in other groups of this subclass
-
- 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
- H04L1/0054—Maximum-likelihood or sequential decoding, e.g. Viterbi, Fano, ZJ algorithms
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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
- H04L5/02—Channels characterised by the type of signal
- H04L5/023—Multiplexing of multicarrier modulation signals
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L25/00—Baseband systems
- H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
- H04L25/03—Shaping networks in transmitter or receiver, e.g. adaptive shaping networks
- H04L25/03006—Arrangements for removing intersymbol interference
- H04L2025/0335—Arrangements for removing intersymbol interference characterised by the type of transmission
- H04L2025/03375—Passband transmission
- H04L2025/03414—Multicarrier
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L25/00—Baseband systems
- H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
- H04L25/03—Shaping networks in transmitter or receiver, e.g. adaptive shaping networks
- H04L25/03006—Arrangements for removing intersymbol interference
- H04L2025/0335—Arrangements for removing intersymbol interference characterised by the type of transmission
- H04L2025/03426—Arrangements for removing intersymbol interference characterised by the type of transmission transmission using multiple-input and multiple-output channels
Definitions
- the present invention relates to a MIMO receiving apparatus and receiving method for performing multiple input multiple output (MIMO) communication in wireless communication for performing communication using a wireless technology, and in particular, to single carrier MIMO signals.
- the present invention relates to a MIMO receiving apparatus and receiving method for converting a signal into a frequency domain and performing MIMO signal separation by processing in the frequency domain.
- High-speed data transmission is required in the wireless system of next-generation mobile communication.
- a plurality of transmit antennas transmit data signals using the same frequency, and multiple receive antennas are used to demodulate data signals.
- Multiple Input Multiple Output (MIMO) ) Multiplex is noted.
- FIG. 1 is a diagram showing an example of a configuration of a conventional MIMO transmission / reception system using MIMO multiplexing.
- the transmitting side is a transmitter 201.
- the transmitting antenna 202-1 to 202-M, and the receiving side is also configured from the receiving antenna 203-1 to 203-N and the receiving device 204.
- Transmission bandwidth by transmitting different data signals using the same frequency using multiple transmitting antennas 202-1 to 202-M power and receiving data signals using multiple receiving antennas 203-1 to 203-N.
- High-speed data transmission can be performed in proportion to the number of transmitting antennas without increasing the
- the receiving apparatus 204 needs to demodulate (separate) each data signal transmitted from the plurality of transmitting antennas 202-1 to 20 2-M from the signals received by the plurality of receiving antennas 203-1 to 203 -N. There is.
- MMSE Minimum Mean Square Error
- MLD Maximum Likelihood Detection
- the terminal in the uplink radio scheme for next-generation mobile communication, it is necessary for the terminal to achieve high transmission power efficiency in order to expand the communication area, and the low peak power to average power ratio (PAPR: Peak to Average)
- PAPR Peak to Average
- SC Single Carrier
- MIMO multiplexing is performed in the SC scheme, multipath interference is a problem.
- MIMO signal separation is performed using an MMSE filter, it is necessary to simultaneously perform MIMO signal separation and suppression of multipath interference, that is, an MMSE filter (two-dimensional MMSE filter) in the spatial direction and in the temporal direction.
- the combination of a two-dimensional MMSE filter and transmit antenna interference cancellation is considered to be promising because of its excellent characteristics.
- FIG. 2 is a diagram showing an example of configuration of a conventional MIMO receiver.
- an increase in the amount of computation is suppressed by performing two-dimensional MMSE equalization and transmission antenna interference removal by signal processing in the frequency domain.
- a method of improving the characteristics by repeatedly performing the two-dimensional frequency domain equalization and the reception processing of antenna interference removal is considered (for example, two-dimensional MMSE weights are applied to the frequency domain repeated PIC).
- Throughput characteristics of SC-MIMO multiplexing to be used "Akinori Nakajima, Fumiyuki Adachi, IEICE Technical Report, RCS 2005- 88, pp. 19- 24, see October 2005.).
- the MIMO receiving apparatus shown in FIG. 2 uses N single carrier MIMO signals transmitted from M (M is an integer of 2 or more) transmit antennas as N (N is an integer of 2 or more) receive antennas. It is a MIMO receiver that performs MIMO signal separation by processing it in the frequency domain.
- This MIMO receiving apparatus includes receiving antennas 101-1 to 101-N, a cyclic prefix (CP: Cvclic Prefix) removing unit 102-1 to 102-N, and discrete Fourier transform (DFT: Disc rete Fourier Transform) units 103-1 to 103-N, reception filters 104-1 to 104 N, subtraction units 105, channel estimation units 106, weight calculation units 107, two-dimensional frequency domain equalization units 108, , Discrete Inverse Fourier Transform (IDFT: Inverse Discrete Fourier Tra nsform ⁇ 109 l-109-M bit likelihood calculation unit 110-1: L 10-M, Symmetry replica generation ⁇ 1-: L 11 M, DFT ⁇ — 1 to 112 M M M and antenna interference replica generation unit 113 1 ⁇ 1 to 113 M M and force configuration.
- IDFT Discrete Inverse Fourier Transform
- FIG. 3 is a diagram showing an example of a radio frame format in the case of using frequency domain equalization.
- the frame shown in FIG. 3 shows a radio frame signal transmitted from one certain transmitting antenna.
- the radio frame signal is composed of a plurality of pilot signals, and is composed of blocks of data signals, and in the example shown in FIG. 3, there is a pilot signal block at the head and a plurality of data blocks follows in succession. .
- a CP is added to avoid multipath interference from the previous block during DFT processing.
- CP is a signal generated by copying the last data of each pro- gram to the front.
- MIMO it is necessary to estimate the channel gain between the transmit antenna and the receive antenna, and it is preferable that the pilot signals of each transmit antenna be orthogonal to one another.
- frequency multiplexing using IFDM Interleaved Frequency Division Multiplexing
- code multiplexing using cyclically shifted CAZAC Constant Amplitude Zero Auto-Correlation
- receiving antennas 101-1 to 101-N shown in FIG. 2 receive single carrier MIMO signals.
- CP removing sections 102-1 to 102-N receive the respective receiving antenna signals, and remove the signal corresponding to CP at common timing.
- DFT sections 103-1 to 103-N receive, as input, each receive antenna signal from which CP has been removed,
- N DFT1 (N DFT1 is an integer of 2 or more) Performs DFT of points and transforms the received signal into the frequency domain.
- Reception filters 104-1 to 104-N perform filtering of the received signal in the frequency domain, waveform shaping, noise suppression, Perform user separation etc. In general, a raised cosine roll-off filter is used for the reception filters 104-1 to 104-N.
- the reception filters 104-1 to 10 4 -N may also be performed in the time domain signal processing prior to the force DFT units 103-1 to 103 -N performed in the signal processing in the frequency domain. it can.
- Subtraction section 105 leaves the transmission antenna signal to be demodulated and subtracts other transmission antenna interference replicas.
- FIG. 4 is a diagram showing an example of a configuration of subtraction section 105 for the DFT signal of reception antenna n.
- Subtraction unit 105 shown in FIG. 4 is configured of replica combination units 121-1 to 121-M and subtractors 122-1 to 122-M.
- the replica combining units 121-1 to 121-M combine transmission antenna interference replicas except for the transmission antenna signal to be demodulated.
- the subtractors 122-1 to 122-M subtracts the output of the replica combining unit 121-1 to 121-M from the DFT signal of the receiving antenna n.
- Equation 5 ik) ⁇ R ⁇ (k) is a column vector of N rows) Is expressed by the following equation.
- Channel estimation section 106 estimates the channel gain between the transmit antenna and the receive antenna in the frequency domain using a pilot signal inserted for each transmit antenna.
- FIG. 5 is a diagram showing an example of a configuration of channel estimation section 106 for obtaining the channel gain of transmit antenna m in receive antenna n.
- Channel estimation section 106 shown in FIG. 5 is configured of DFT section 131, transmission / reception filter 132, reference signal generation section 133, correlation processing section 134, and noise suppression section 135.
- the DFT unit 131 DFTs the pilot code of the transmitting antenna m and converts it into a frequency domain signal.
- the transmit and receive filter 132 passes the frequency domain signal of the pilot code to the transmit and receive filter.
- the reference signal generation unit 133 uses the output of the transmission / reception filter 132 to calculate a pilot reference signal used for correlation processing with the received pilot signal.
- the correlation processing unit 134 estimates channel gain by correlation processing between a pilot received signal in the frequency domain and a pilot reference signal.
- the noise suppression unit 135 suppresses the noise of the channel gain estimated by the correlation processing unit 134, and improves the signal power-to-noise ratio (S ZN ratio) of the channel estimation value which is the estimated channel gain.
- S ZN ratio signal power-to-noise ratio
- the channel estimation unit 106 having the configuration shown in FIG. 5 can also perform signal processing in the time domain prior to the force DFT units 103-1 to 103-N performed in signal processing in the frequency domain.
- Weight calculating section 107 calculates weights for two-dimensional frequency domain equalization using channel estimation values between the transmitting antenna and the receiving antenna.
- the weight calculator 107 generally uses an M MSE algorithm. Transmit antenna m'th iterated MMSE weight
- H ⁇ k) (Cfr) is an N-by-M matrix
- H ⁇ k H x ⁇ k),-, H m ⁇ k),-, M () ... (Expression 4)
- H m (k) ⁇ H m :) is a row vector of N rows
- the ith repeated soft decision symbol replica in the time domain of transmit antenna m For example, the ith repeated soft decision symbol replica in the time domain of transmit antenna m
- N SYMB is the number of symbols of the data block.
- the two-dimensional frequency domain equalization unit 108 receives the two-dimensional equalization weight calculated by the weight calculation unit 107 and the output of the subtraction unit 105 as input, and multiplies each by subcarrier to obtain a frequency. Simultaneously perform MIMO signal separation and multipath interference suppression in the domain.
- Weight meter The weight calculated by the calculation unit 107 is
- IDFT sections 109-1 to 109-M receive as input the equalization signal of each transmitting antenna that is the output of two-dimensional frequency domain equalization section 108,
- N IDFT (N IDFT is an integer greater than 1) Performs IDFT of points and converts the equalized signal to the time domain.
- the output of the i-th iteration (i 1 1) of the IDFT unit 109-1-109-M is the final demodulated signal.
- Bit likelihood calculators 110-1 to 110-M calculate the likelihood for each bit transmitted from the equalized signal of each transmit antenna.
- the bit likelihood calculation unit 110-1: L10-M also includes the case where the bit is determined hard.
- the symbol replica generation units 111-1-11 -M are used to transmit the symbols transmitted from the respective transmission antennas.
- a symbol replica of transmit antenna m is generated from the likelihood of A method of generating a hard decision symbol replica, a method of generating a hard decision symbol replica, and multiplying a predetermined replica weight coefficient (a constant of 1 or less) to the symbol replica generation units 111 1 to 111 M;
- a method of generating a soft decision symbol replica or the like is used.
- the method of generating soft decision symbol replicas has good characteristics!
- DFT sections 112-1 to 112-M receive as input symbol replicas of the respective transmitting antennas generated at symbol replica generating sections 111-1 to L 11-M,
- N DFT2 (N DFT2 is an integer greater than or equal to 2) Performs a DFT of points, and converts the symbol replica into the frequency domain.
- Antenna interference replica generation sections 113-1 to 113-M generate transmission antenna interference replicas using symbol replica signals in the frequency domain of each transmission antenna and channel estimation values.
- Equation 28 is expressed by the following equation.
- the present invention converts a single carrier MIMO signal into a signal in a frequency domain, and performs MIMO signal separation by processing in the frequency domain, in a two-dimensional frequency domain.
- weights for antenna interference cancellation and two-dimensional frequency domain equalization can be obtained.
- the present invention aims to provide a MIMO receiving apparatus and a receiving method capable of realizing excellent MIMO reception characteristics because the amount of calculation operation can be reduced and multipath interference of not only other antenna interference but also transmission antennas to be demodulated can be eliminated. Do.
- a MIMO receiving apparatus which receives single carrier signals transmitted from a plurality of transmitting antennas provided in a transmitting apparatus by a plurality of receiving antennas, and separates the signals according to a frequency domain
- a D FT unit that performs discrete Fourier transform on the signal received by the receiving antenna at a first point
- a replica regeneration unit that performs two-dimensional frequency domain equalization based on the weight calculated using the channel gain, and generates an interference replica of each transmission antenna and a distortion-free signal replica
- a subtraction unit that removes the interference replicas of all the transmission antennas of the signal antenna which has been discrete Fourier transformed by the DFT unit;
- the signal from which the interference replica has been removed is subjected to two-dimensional frequency domain equalization with weights calculated based on the interference removal of the subtracting unit using the channel gain, and the equalized signal is not distorted.
- a demodulation unit that adds the signal replicas and demodulates the transmitted signal.
- a plurality of subtraction units and a plurality of replica reproduction units are further provided downstream of the replica reproduction unit, and antenna interference removal and replica reproduction processing are repeatedly performed.
- the present invention is characterized in that transmission antenna signals are simultaneously demodulated to remove antenna interference in parallel.
- the transmission antenna signal is ordered based on the reception quality, and the transmission antenna signal power is demodulated and the antenna interference is sequentially eliminated.
- a weight calculator configured to calculate weights of two-dimensional frequency domain equalization using a channel estimation value between the transmitting antenna and the receiving antenna;
- a two-dimensional frequency domain equalizer that performs MIMO signal separation and multipath interference suppression in the frequency domain by using the weight and the signal output from the subtractor as inputs and multiplying each of the weights for each subcarrier.
- An IDFT unit for performing discrete inverse Fourier transform on a demodulation signal of each transmitting antenna, which is an output signal, at a second point;
- a bit likelihood calculator that calculates bit likelihood for each transmitted bit based on the demodulated signal of each transmitting antenna
- a symbol replica generation unit that generates a symbol replica based on the bit likelihood; a DFT unit that performs discrete Fourier transform on the symbol replica at a third point; An antenna interference replica generation unit that generates a transmission antenna interference replica using a symbol replica signal in the frequency domain and a channel estimation value;
- a distortion-free signal replica generation unit configured to generate a distortion-free signal replica using the symbol replica signal in the frequency domain and an average subcarrier gain of channel gain after two-dimensional frequency domain equalization.
- a weight calculating unit that calculates weights of two-dimensional frequency domain equalization based on interference cancellation of the subtracting unit using a channel estimation value between the transmitting antenna and the receiving antenna;
- a two-dimensional frequency domain equalizer that performs MIMO signal separation and multipath interference suppression in the frequency domain by using the weight and the signal output from the subtractor as inputs and multiplying each of the weights for each subcarrier.
- An addition unit that adds a non-distortion signal replica to the signal output from the two-dimensional frequency domain equalization unit;
- an IDFT unit for performing discrete inverse Fourier transform on a demodulated signal of each of the transmitting antennas, which is a signal output from the adding unit, at a second point.
- the plurality of replica reproduction units provided in the subsequent stage of the replica reproduction unit may be configured to calculate weights of two-dimensional frequency domain equalization using a channel estimation value between the transmission antenna and the reception antenna.
- a weight calculating unit that calculates based on the interference removal of the subtracting unit;
- a two-dimensional frequency domain equalizer that performs MIMO signal separation and multipath interference suppression in the frequency domain by using the weight and the signal output from the subtractor as inputs and multiplying each of the weights for each subcarrier.
- An addition unit that adds a non-distortion signal replica to the signal output from the two-dimensional frequency domain equalization unit;
- An IDFT unit that performs discrete inverse Fourier transform on a demodulated signal of each transmitting antenna, which is a signal output from the adding unit, at a second point;
- a symbol replica generation unit that generates a symbol replica based on the bit likelihood; a DFT unit that performs discrete Fourier transform on the symbol replica at a third point; and transmitting using a symbol replica signal in a frequency domain and a channel estimation value
- An antenna interference replica generation unit that generates an antenna interference replica
- a distortion-free signal replica generation unit configured to generate a distortion-free signal replica using the symbol replica signal in the frequency domain and an average subcarrier gain of channel gain after two-dimensional frequency domain equalization.
- the replica reproduction unit further includes a decoding unit at a stage subsequent to the bit likelihood calculation unit, and generates a symbol replica using an error correction decoded bit.
- the plurality of replica reproduction units provided in the subsequent stage of the replica reproduction unit further includes a decoding unit in the subsequent stage of the bit likelihood calculation unit, and generates a symbol replica using the error correction decoded bits It is characterized by
- the MIMO reception method is a MIMO reception method in which a single carrier signal to which a plurality of transmit antenna powers are also transmitted is received by a plurality of receive antennas, and the signals are separated by frequency domain processing.
- a single carrier signal transmitted from a plurality of transmitting antennas is received by a plurality of receiving antennas, and a signal is transmitted from a frequency domain.
- the signal strength of the interference replica of the antenna is removed before the two-dimensional frequency domain equalization is performed, and the interference replica of the antenna is removed after the two-dimensional frequency domain equalization is performed.
- the distortion-free signal replica is added to the received signal.
- transmission is performed from a plurality of transmission antennas.
- a single-carrier signal is received by multiple receive antennas, and the MIMO receiver that separates the signals according to the frequency domain receives the interference replica of the antenna before performing two-dimensional frequency domain equalization. Since the distortion-free signal replica is added to the signal from which the interference replica of the antenna has been removed after removing the signal strength and performing two-dimensional frequency domain equalization, an excellent MIMO reception characteristic can be realized.
- FIG. 1 is a diagram showing a configuration example of a conventional MIMO transmission / reception system using ⁇ multiplexing.
- FIG. 2 is a diagram showing an example of configuration of a conventional MIMO receiver.
- FIG. 3 is a diagram showing an example of a radio frame format in the case of using frequency domain equalization.
- Fig. 4 is a diagram showing an example of a configuration of a subtracting unit for the DFT signal of the receiving antenna n.
- FIG. 5 is a diagram showing a configuration example of a channel estimation unit for obtaining a channel gain of a transmitting antenna m in a receiving antenna n.
- FIG. 6 is a diagram showing a first embodiment of the MIMO receiving apparatus of the present invention.
- FIG. 7 is a diagram showing a second embodiment of the MIMO receiving apparatus of the present invention.
- FIG. 8 is a view showing a combination of the first embodiment shown in FIG. 6 and the second embodiment shown in FIG. 7;
- FIG. 9 is a diagram showing the configuration of a subtracting unit for the DFT signal of the receiving antenna n.
- FIG. 6 is a diagram showing a first embodiment of the MIMO receiving apparatus of the present invention.
- the MIMO receiving apparatus has N (M is an integer of 2 or more) N single carrier MIMO signals transmitted by M (M is an integer of 2 or more) transmitting antennas.
- the MIMO receiver performs MIMO signal separation by processing at the frequency domain.
- This MIMO receiver comprises receiving antennas 1 1 to 1 N, a DFT unit 51, a channel estimation unit 52, a replica reproduction unit 53, a subtraction unit 54, and a demodulation unit 55.
- DFT unit 51 is a first point of the signal received by receiving antenna 1-1-1 -N.
- N DFT1 is an integer of 2 or more points.
- the channel estimation unit 52 estimates channel gain between the transmit antenna and the receive antenna using a pilot signal inserted in the signal transmitted from each transmit antenna.
- the replica reproduction unit 53 performs two-dimensional frequency domain equalization based on the weight calculated using the channel gain, and at the same time, the interference replica that mimics the interference signal of each transmitting antenna, the absence of distortion, and the absence of a signal. And generate a distortion signal replica.
- the subtraction unit 54 also removes interference replicas of all transmission antennas for the signal strength output from the DFT unit 51.
- the demodulator 55 performs two-dimensional frequency domain equalization with the weight calculated based on the interference cancellation of the subtraction unit 54 using the channel gain for the signal from which the interference replica has been removed. Undistorted signal replicas are added to demodulate each transmit antenna signal.
- subtracting section 54 removes interference replicas of all the transmitting antennas, and after two-dimensional frequency domain equalization of demodulating section 55, each transmitting antenna signal is not present.
- distortion signal replicas it is possible to eliminate not only other-antenna interference but also multi-noise interference of the transmission antenna to be demodulated. Therefore, superior MIMO reception characteristics can be realized without increasing the amount of computation conventionally.
- FIG. 7 is a diagram showing a second embodiment of the MIMO receiver of the present invention.
- the MIMO receiving apparatus in this embodiment further subtracts K stages (K is an integer of 1 or more) downstream of replica reproducing section 53 of the first embodiment shown in FIG. It comprises a unit 56-1 to 5-6-K and a replica reproduction unit 57-1 to 57-K.
- the MIMO receiver shown in FIG. 7 receives M (M is an integer of 2 or more) transmit antenna powers and N transmitted single carrier M1 MO signals are received by N (N is an integer of 2 or more) receive antennas. It is a MIMO receiver that performs MIMO signal separation by frequency domain processing.
- This MIMO receiving apparatus includes receiving antennas 1-1 to 1-N, a DFT unit 51, a channel estimation unit 52, a replica reproduction unit 53, subtraction units 56-1 to 56-K, and a replica reproduction unit 57. 1 to 57-K, a subtracting unit 54, and a demodulating unit 55.
- the DFT unit 51 is a first point of the signal received by the receiving antennas 1-1-1-N.
- N DFT1 DFT is performed at points (N DFri is an integer of 2 or more).
- the channel estimation unit 52 estimates channel gain between the transmit antenna and the receive antenna using a pilot signal inserted in the signal transmitted from each transmit antenna.
- the replica reproducing unit 53 performs two-dimensional frequency domain equalization based on the weight calculated using the channel gain, and generates an interference replica of each transmission antenna and an undistorted signal replica.
- the subtractors 56-1 to 56-K remove the interference replicas of all the transmitting antennas of the signal strength output from the DFT unit 51, respectively.
- the replica reproduction units 57-1 to 57-K perform two-dimensional frequency domain equalization with weights calculated in consideration of the interference removal of the subtraction units 56-1 to 56-K from the channel gain.
- an undistorted signal replica is added to the output to demodulate each transmitting antenna signal, and an interference replica of each transmitting antenna and an undistorted signal replica are generated.
- the subtractor 54 is connected to the DFT 51 Output signal strength Remove the interference replicas of all transmitting antennas.
- the demodulation unit 55 performs two-dimensional frequency domain equalization on the signal from which the interference replica has been removed, using the channel gain, based on the interference removal of the subtraction unit 54, to obtain an equalized signal. And a distortion-free signal replica to demodulate each transmitting antenna signal.
- interference replicas of all transmission antennas are removed by subtraction units 56-1 to 56-K and subtraction unit 54, and replica reproduction units 57-1 to 57-K and demodulation units
- An arrangement is made such that an undistorted signal reflector is added to each transmitting antenna signal after two-dimensional frequency domain equalization of 55.
- not only other-antenna interference but also multipath interference of the transmission antenna to be demodulated can be eliminated, so that excellent reception characteristics can be realized without increasing the amount of power calculation of the conventional one.
- by performing high-precision replica generation by repeatedly performing antenna interference cancellation and replica reproduction processing it is possible to further improve the reception characteristics.
- FIG. 8 is a diagram showing an embodiment in which the first embodiment shown in FIG. 6 and the second embodiment shown in FIG. 7 are combined.
- the decoy receiving apparatus has the receiving antennas 1 1 to 1 ⁇ , etc. Removal part 2-1-2-? ⁇ , DFT 3-1-3-N Reception filter 4 1-4-N, subtractor 5, channel estimation unit 6, weight calculator 7, two-dimensional frequency domain equalizer 8, and adder 9, IDFT 3 ⁇ 4 10-1 to 10—M-bit likelihood calculator 11-1 to: L 1- M, symbol replica generator 12-1 to 12-M, and DFT 3 ⁇ 413 1 to 13- M antenna interference It comprises a replica generation unit 14-1 to 14-M and a distortion-free signal replica generation unit 15-1 to 15-M.
- Receiving antennas 1-1-1-N receive single carrier MIMO signals.
- the CP removing unit 2-1 to 2- ⁇ receives the signals received by the respective receiving antennas 11 to 1-N, and removes the signal corresponding to the CP at common timing.
- DFT 3 ⁇ 43 1 to 3 ⁇ i ⁇ 3 ⁇ 4 With each receive antenna signal from which CP has been removed as input, this is the first point
- N DFT1 (N DFT1 is an integer of 2 or more) Perform DFT of points to transform the received signal into the frequency domain.
- the receive filters 4 1 to 4 N perform filtering of received signals in the frequency domain, and perform waveform shaping, noise suppression, user separation, and the like. In general, a raised cosine rolloff filter is used as the reception filter 4 1-4.
- the reception filters 4-1 to 4N can also be performed in the time domain signal processing prior to the force DFT units 3-1 to 3N performed in the signal processing in the frequency domain.
- the subtraction unit 5 subtracts all transmission antenna interference replicas including the transmission antenna signal to be demodulated.
- FIG. 9 is a diagram showing a configuration of subtraction section 5 for the DFT signal of reception antenna n.
- the subtractor 5 shown in FIG. 9 is composed of a replica synthesizer 21 and a subtractor 22.
- the replica combiner 21 combines all transmit antenna interference replicas.
- the subtractor 22 subtracts the output of the DFT signal from the replica combining unit 21 of the receiving antenna n. Subcarrier after DFT
- R () (R ik) be an N-row column vector) and let the ith iterative interference replica of the transmit antenna m
- N is the column vector of N rows, and the equalization signal for each transmit antenna after the i-th iterative interference cancellation
- Equation 10 It becomes.
- the calculation of antenna interference cancellation of equation (9) is common to each transmitting antenna, so the amount of computation can be reduced compared to the conventional one.
- the channel estimation unit 6 estimates the channel gain between the transmitting antenna and the receiving antenna in the frequency domain using the pilot signal inserted in the signal transmitted from each transmitting antenna.
- the channel estimation unit 6 can also perform signal processing in the time domain prior to the force DFT units 3-1 to 3-N performed in signal processing in the frequency domain.
- Weight calculating section 7 calculates weights of two-dimensional frequency domain equalization using a channel estimation value which is a channel gain between the transmitting antenna and the receiving antenna estimated by channel estimating section 6. .
- the weight calculation unit 7 generally uses an MMSE algorithm. Transmit antenna m ith repetition MMSE weight
- W ⁇ ⁇ k) ((k) is an N-column row vector) is the channel estimate matrix
- H ⁇ k) () is an N-by-M matrix) and noise power [0099] [Number 41]
- H ⁇ k ⁇ H 1 ⁇ k), H m ⁇ k), ..., M ( ⁇ ⁇ ⁇ (Equation 12). Also,
- H m ⁇ k) (H m (k) is a row vector of N rows) is a channel estimate between the transmit antenna m and the receive antenna.
- the average power of is calculated by the following equation.
- NsYMB is the number of symbols of the data block.
- the calculation of the inverse matrix [] -1 is common to the transmitting antenna m, and the amount of calculation can be reduced compared to the conventional one that can be performed only once.
- the two-dimensional frequency domain equalization unit 8 receives the two-dimensional equalization weight calculated by the weight calculation unit 7 and the output of the subtraction unit 5 as inputs, and multiplies them for each subcarrier to obtain a frequency domain. Simultaneously perform MIMO signal separation and multipath interference suppression and output. Weight calculated by weight calculator 7
- N IDFT (N IDFT is an integer of 2 or more) Performs IDFT of points and converts the demodulated signal into the time domain.
- Bit likelihood calculators 11 1 to 11 M calculate the likelihood for each transmitted bit based on the demodulated signal of each transmission antenna.
- the bit likelihood calculators 11-1 to 11-M also include cases where the bit is hard-decided.
- the symbol replica generation units 12-1 to 12-M generate symbol replicas of the transmission antenna m based on the bit likelihood of the bits transmitted from the respective transmission antennas.
- a method of generating a hard decision symbol replica, a method of generating a hard decision symbol replica, and multiplying a predetermined replica weighting factor (a constant of 1 or less) in the symbol replica generator 12-1 to 12-M A method of generating a determination symbol replica or the like is used.
- error correction decoding is performed in the subsequent stage of bit likelihood calculation units 11 1 to 11 N in order to perform high-accuracy replica generation that generates a symbol replica from the bits after demodulation.
- DFT units 13-1 to 13-M receive the symbol replica of each transmit antenna generated by symbol replica generation units 12-1 to 12-M as the third point.
- N DFT2 (N DFT2 is an integer greater than or equal to 2) Performs a DFT of points, and converts the symbol replica into the frequency domain.
- the antenna interference replica generation units 14-1 to 14-M generate transmission antenna interference replicas using symbol replica signals in the frequency domain of each transmission antenna and channel estimation values.
- Symbol replica signal of frequency domain of transmitting antenna m [Number 60]
- Undistorted signal replica generation units 15-1 to 15-M use symbol replica signals in the frequency domain of each transmission antenna and subcarrier average values of channel gains after two-dimensional frequency domain equalization. To generate an undistorted signal replica.
- M m be the i-th repeated undistorted signal replica of the transmitting antenna m [Number 66]
- each iterative process of antenna interference cancellation and replica reproduction is performed.
- each transmit antenna signal is simultaneously demodulated, and antenna interference replicas are removed in parallel.
- a method is also conceivable in which the transmit antenna signal is ordered based on the reception quality in each iterative process, the transmit antenna signal power of good quality is demodulated, and antenna interference is sequentially eliminated. Specifically, the reception quality of the first (0th iteration) reception process! ⁇ ⁇ Demodulate in order from the transmitting antenna signal and remove the interference replica from the DFT signal.
- the time domain signal power is also converted to the frequency domain signal by DFT, and the conversion from the frequency domain signal to the time domain signal is performed by IDFT, but the fast Fourier transform (FFT) is performed.
- FFT fast Fourier transform
- Fast Fourier Transform Inverse Fast Fourier Transform
- IFFT Inverse Fast Fourier Transform
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CN200780013153.8A CN101421943B (zh) | 2006-04-13 | 2007-02-02 | Mimo接收装置 |
US12/297,125 US8351553B2 (en) | 2006-04-13 | 2007-02-02 | MIMO receiving apparatus and receiving method |
JP2008510737A JP4780348B2 (ja) | 2006-04-13 | 2007-02-02 | Mimo受信装置および受信方法 |
KR1020087025406A KR101052985B1 (ko) | 2006-04-13 | 2007-02-02 | Mimo 수신 장치 및 수신 방법 |
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JP2010119070A (ja) * | 2008-11-11 | 2010-05-27 | Tokyo Institute Of Technology | 位相雑音補償受信機 |
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JPWO2007119280A1 (ja) | 2009-08-27 |
JP4780348B2 (ja) | 2011-09-28 |
US8351553B2 (en) | 2013-01-08 |
CN101421943A (zh) | 2009-04-29 |
CN101421943B (zh) | 2014-12-10 |
KR20080104381A (ko) | 2008-12-02 |
KR101052985B1 (ko) | 2011-07-29 |
US20090262853A1 (en) | 2009-10-22 |
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