JP2007049267A - Receiver of wireless communication system, method and program for detecting wireless signal transmitted from transmitter and recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a receiver of a wireless communication system in which manufacturing cost can be held down low by reducing the throughput in detection processing of a transmission signal vector s and reducing the circuit scale. <P>SOLUTION: In the receiver of the wireless communication system performing MIMO communication, detection order is determined for N<SB>T</SB>transmission signals, column vectors of a propagation path matrix H are rearranged on the basis of the signal detection order, the rearranged matrix is subjected to QR decomposition and then that matrix is transformed into a unitary matrix Q and an upper triangular matrix R. A received vector x is filtered using the unitary matrix Q and then a wireless signal transmitted by each of N<SB>T</SB>transmission antenna is detected by backward substitution using the upper triangular matrix R and the results of filtering. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

The present invention relates to a transmission apparatus including N _T (N _T ≧ 2, N _T is an integer) transmission antennas each transmitting a radio signal using the same frequency channel, and N _R transmission radio signals are transmitted. Transmission of a receiving apparatus and a transmitting apparatus of a wireless communication system that performs MIMO (Multiple Input Multiple Output) communication configured with a receiving apparatus that receives each of the receiving antennas (N _R ≧ N _T ≧ 2, N _R is an integer) The present invention relates to a method for detecting a radio signal, a program thereof, and a recording medium.

In a multi-input multi-output digital radio communication system such as MIMO, a transmission apparatus includes _NT transmission antennas that transmit radio signals, and a reception apparatus receives N _R transmission antennas that receive the transmitted radio signals. A receiving antenna is provided. That is, in such a multi-input multi-output digital wireless communication system, the transmission device sends out a transmission signal s having _NT signal elements, and these signals reach the reception device side through the propagation path. Received as a received signal x having N _R signal elements. And, if the noise generated in the receiving system corresponding to each antenna on the receiving device side is w,

It can be expressed by a mathematical relationship such as Incidentally, x is N vector of received signal having a _{R-dimensional} signal-element, s is the vector of transmitted signals having a signal component of the N _T dimensional, w is N _{R-dimensional} noise vector, H is the N _R rows N _T columns Represents a propagation path matrix.

In the multi-input multi-output digital wireless communication system as described above, the receiving apparatus uses the detected received signal vector x, the known propagation path matrix H, and the noise w in order to realize the communication purpose. It is required to accurately detect the transmission signal vector s. A technique for separating a plurality of transmission signals simultaneously transmitted in the same frequency band in a MIMO system on the receiving side has been disclosed (see Non-Patent Document 1).
PWWolniansky and three others, "V-BLAST: An Architecture for Realizing Very High Data Rates Over the Rich-Scattering Wireless Channel", Bell Laboratories, Lucent Technologies, Crawford Hill Laboratory, Signals, Systems, and Electronics, 1998. ISSSE 98. 1998 URSI International Symposium on 29 Sept.-2 Oct. 1998 Page (s): 295-300

Here, the detection processing of the transmission signal vector s in the related art is the following processing procedure.
(A) The order in which each signal is detected for N _T transmission signals is determined (N _T iterative calculations are required).
(B) with respect to the N _T transmitted signals, (requires N _T iterations calculations) to determine the N _T number of extraction vectors for detecting (nulling vector or weight vector), respectively.
(C) The transmission signal s is detected using the extraction vector generated in (b) in accordance with the order determined in (a) above (N _T iterations are required).
And (d) updating the receive vector x with channel matrix H (required N _T iterations calculation).

However, as shown in the above (a) to (d), the following problem occurs in the detection processing of the transmission signal vector s.
(1) _NT pseudo-inverse matrix computation is required, and the required computation amount is enormous.
(2) The pseudo-inverse matrix calculation process requires a large storage capacity, and every time a calculation result of the pseudo-inverse matrix is written to a storage device such as a memory, a processing load is applied.
(3) Since the circuit scale is proportional to the required amount of computation, the required circuit scale is therefore very large, making it difficult to reduce the size of the apparatus.
(4) Since the required calculation amount is large, the required power consumption is proportionally increased, and the operating life of the apparatus (drive time by the battery) is shortened.
(5) Since the _NT pseudo-inverse matrix operation cannot be parallelized, the processing delay is very large, and signal processing in real time becomes extremely difficult.

  Therefore, the present invention reduces the processing amount in the detection processing of the transmission signal vector s and the circuit scale, thereby reducing the manufacturing cost. The receiving apparatus of the wireless communication system and the wireless transmitted by the transmitting apparatus can be reduced. It is an object of the present invention to provide a signal detection method, a program thereof, and a recording medium.

To achieve the above object, the present invention, N _T present for transmitting a radio signal respectively, using the same frequency channel (N _T ≧ 2, N _T is an integer) and the transmission device having a transmission antenna, said transmission Communication system for performing MIMO (Multiple Input Multiple Output) communication comprising receiving apparatuses that receive received radio signals with N _R (N _R ≧ N _T ≧ 2, N _R is an integer) receiving antennas, respectively. A signal detection order determining means for determining each signal detection order for the N _T transmission signals, and a column vector of the propagation path matrix H based on the signal detection order. Channel matrix rearranging means for rearranging, matrix transforming means for QR-decomposing the rearranged matrix and converting the matrix into a unitary matrix Q and an upper triangular matrix R; and the unitary matrix Q A received vector filtering means for filtering the received vector x by using the transmission by using the results of the filtering and the upper triangular matrix R, detecting each said N _T present a radio signal transmitted on each transmit antenna of the backward substitution And a time radio signal detecting means.

  Further, in the present invention, the signal detection order determination unit calculates a norm of each column vector of the propagation path matrix H, calculates a correlation between each column vector of the propagation path matrix H, and calculates the norm and the correlation. Based on the above, the signal detection order is determined.

  The reception vector filtering means may filter the reception vector x by multiplying the complex conjugate transpose of the unitary matrix Q and the reception vector x.

In the present invention, the transmission radio signal detection means sequentially obtains each element of the reception vector obtained by the filtering result using the triangular structure of the upper triangular matrix R, and the soft decision result of each element Then, by obtaining a hard decision result by quantization of the soft decision result, each of the radio signals transmitted from the N _T transmitting antennas is detected.

The present invention, N _T present a transmitting device having a transmitting antenna (N _T ≧ 2, N _T integer), the transmitted radio signals N _R for transmitting a radio signal respectively, using the same frequency channel Transmission of the transmission device of a wireless communication system that performs MIMO (Multiple Input Multiple Output) communication constituted by a reception device that receives each of the reception antennas (N _R ≧ N _T ≧ 2, N _R is an integer) The signal detection order determining unit of the receiving apparatus determines each signal detection order for the N _T transmission signals, and the channel matrix rearranging unit of the receiving apparatus. However, the column vector of the propagation path matrix H is rearranged based on the signal detection order, and the matrix conversion means of the receiving device performs QR decomposition on the rearranged matrix, and unitizes the matrix. Column Q and upper triangular matrix R are converted, and the reception vector filtering means of the receiving device filters the reception vector x using the unitary matrix Q, and the transmission radio signal detection means of the receiving device is the upper triangular matrix. A radio signal detection method comprising: detecting a radio signal transmitted from each of the N _T transmit antennas by backward substitution using a matrix R and the filtering result.

  In the wireless signal detection method according to the present invention, the signal detection order determination unit calculates a norm of each column vector of the propagation path matrix H, and correlates each of the column vectors of the propagation path matrix H. And the signal detection order is determined based on the norm and the correlation.

  Further, the present invention is the above-described radio signal detection method, wherein the reception vector filtering means filters the reception vector x by multiplying the complex conjugate transpose of the unitary matrix Q and the reception vector x. And

According to the present invention, in the above-described radio signal detection method, the transmission radio signal detection means uses the triangular structure of the upper triangular matrix R to order each element of the received vector obtained by the filtering result. Each of the radio signals transmitted from the N _T transmitting antennas is detected by obtaining a soft decision result of each element and a hard decision result by quantization of the soft decision result.

The present invention, N _T present a transmitting device having a transmitting antenna (N _T ≧ 2, N _T integer), the transmitted radio signals N _R for transmitting a radio signal respectively, using the same frequency channel A computer of the reception apparatus of a wireless communication system that performs MIMO (Multiple Input Multiple Output) communication, and a reception apparatus that receives each of the reception antennas (N _R ≧ N _T ≧ 2, N _R is an integer) A signal detection order determination process for determining each signal detection order for the _NT transmission signals and a column vector of the propagation path matrix H are arranged based on the signal detection order. A channel matrix rearrangement process for performing the rearrangement, a matrix conversion process for performing QR decomposition on the rearranged matrix and converting the matrix into a unitary matrix Q and an upper triangular matrix R; A received vector filtering process for filtering the received vector x by using the tally matrix Q, by using the results of the filtering and the upper triangular matrix R, the N _T radio signals transmitted by each transmit antenna of the present respectively by back substitution This is a program for causing a computer to execute a radio signal detection process at the time of transmission for detecting.

  According to the present invention, in the signal detection order determination process of the above program, a norm of each column vector of the propagation path matrix H is calculated, a correlation between each column vector of the propagation path matrix H is calculated, and the norm is calculated. The signal detection order is determined based on the correlation and the correlation.

  Further, the present invention is characterized in that the reception vector filtering process of the above program filters the reception vector x by multiplying the complex conjugate transpose of the unitary matrix Q and the reception vector x.

According to the present invention, the transmission radio signal detection processing of the program uses the triangular structure of the upper triangular matrix R to sequentially obtain each element of the reception vector obtained by the filtering result, Each of the radio signals transmitted from the N _T transmitting antennas is detected by obtaining a soft decision result and a hard decision result by quantization of the soft decision result.

  The present invention is a recording medium for storing the above-described program.

According to the present invention, the detection order is determined based on the correlation between the column vectors of the channel matrix H and the norm information of each column vector without calculating the pseudo inverse matrix once. Are subjected to QR decomposition, and the transmission signal is detected in order by one backward substitution using the triangular structure of the R matrix. Therefore, as in the conventional case, the signal detection order is determined and the signal extraction vector is generated in _NT transmission signals by _NT pseudo-inverse matrix calculation, and the transmission signals are detected in order using the extraction vectors. Compared to the method, the required calculation amount is reduced.

Hereinafter, a wireless communication system according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing the configuration of the wireless communication system according to the embodiment. In this figure, reference numeral 10 denotes a transmitter (transmitting device), a modulation encoding unit 11 for modulating the encoded transmission information, and a _{N T} transmit antennas 12-1 to _{12-N T} . Here, a transmission signal transmitted by the transmitting antennas 12-1 to _{12-N T} and Sl to SN _T. The reference numeral 20 denotes a receiver (receiving apparatus) is provided with a _{N R} receive antennas 21 - 1 to _{21-N R,} a signal detection processing unit 22, a demodulation and decoding processing unit 23. Here the reception signal received by the receiving antennas 21 - 1 to _{21-N R} and x1 to xN _R. Further, the receiving antennas 21 - 1 to _{21-N R} noise generated in each of the receiving systems to w1 to wN _R. The transmission signal detected by the signal detection processing unit 22 and s ~ 1~s ~ N _T. Further, H is a propagation path matrix of a radio signal between the transmitter 10 and the receiver 20.

Then, in this radio communication system, received by the receiver 20 is receiving antennas 21 - 1 to _{21-N R} a radio signal transmitted from the transmitter 10. Then, by using a signal detection processing unit 22 is the channel matrix H, the received signal x1 to xN _R, and w1 to wN _R noise, information, prediction of the transmission signal Sl to SN _T transmitted by the transmitter a detection result, calculates the s ~ 1~s ~ _{N T.} At this time, by the following process, as compared with the conventional process, using a technique that can reduce the processing amount, it calculates a predicted transmission signal s ~ 1~s ~ N _T.

FIG. 2 is a diagram illustrating a flow of a predicted transmission signal calculation process.
Next, referring to FIG. 2, it will be described process for calculating the predicted transmission signal s ~ 1~s ~ N _T according to this embodiment.
First, the channel matrix H, the value of the noise w1 to wN _R is measured in advance, and stores the signal detection processing unit 22. The received signal x1 to xN _R is, since the signal to be detected by the receiving antenna 21 - 1 to _{21-N R,} since, by using the information, the signal detection processing unit 22, the predicted transmit signal s ~ 1 It performs a process for calculating ~s ~ _{N T.}

<Step S1>
First, each signal detection order is determined for _NT transmission signals.
In this processing, the signal detection processing unit 22 calculates the norm of each column vector of the propagation path matrix H. The norm calculation is

It is done by. Next, the signal detection processing unit 22 calculates the correlation between the column vectors of the propagation path matrix H. The correlation between each column vector is

It is done by. Further, the signal detection processing unit 22 calculates Expression (4) using the value obtained by Expression (3).

And the signal detection process part 22 calculates Formula (5) using the result of Formula (2) and Formula (4).

The number of calculation results by the above equation (5) is _NT . And this result is rearranged in descending order as shown by Formula (6).

That is, γ _max1 indicates the largest value among γ _k calculated by Equation (6). Then, the detection order of the transmission signals s1 to sN _T is s _Pi (Pi = 1,..., N _T ), and a vector P having each Pi as an element,

And the transmission signal of k (1,..., N _T ) corresponding to the index maxi obtained by the rearrangement of Expression (6) is set as the signal detection order Pi. With the above processing, the order of signal detection can be determined by one calculation. At this time, Pi, maxi, and k are stored in association with each other.

<Step S2>
Next, the order of the column vectors of the propagation path matrix H is rearranged to generate the matrix H˜.

<Step S3>
Also, QR decomposition is performed on the matrix H ~.

The QR decomposition, the matrix H ~ a _{N R} rows _{N T} columns, and column unitary matrix Q to the _{N R} rows _{N T} columns is to decompose the _{N T} row _{N T} upper triangular matrix R of the column. The column unitary matrix Q is a matrix whose column vector norm is always 1, and the upper triangular matrix R is a matrix in which all the elements below the physique elements of the matrix are 0. This QR decomposition can be performed by one calculation.

<Step S4>
Next, the received vector x is filtered using the matrix Q. At this time, the signal detection processing unit 22 multiplies the complex conjugate transpose of the matrix Q and the reception vector x. Then, Formula (10) is obtained.

  Note that s˜ is obtained by rearranging the elements of the transmission vector s according to the vector P. Then, rearrangement can be realized by the calculation of equation (10).

<Step S5>
Next, using the triangular structure of the matrix R, _NT predicted transmission signals s˜ are sequentially detected by backward substitution. In this process, equation (11)

Using

The soft decision result is obtained. Moreover, Formula (12)

Quantize the soft decision result using

The hard decision result is obtained. Then, equation (11), by the equation (12), one element 1 of s ~ but is output, by repeating _this, and outputs the _{s pnt} from _{s p1.}

<Step S6>
Next, the rearrangement opposite to the rearrangement performed in step S2 is performed on (s _{p1 ···} s _{pi ···} s _pNT ) output in step S5. That is, Pi, maxi, and k are stored in association with each other in step S1, but are rearranged in the order of k. This

_NT predicted transmission signals s˜ as shown in FIG.

Note that symbols and terms are defined as follows in the mathematical formulas shown in the present embodiment.
a _i: or (A) _i: = i-th vector of matrix A a _j: or (A) _{: j} = j-th column vector of matrix A a _ij = element A ^H = i-th row and j-th column of matrix A = Complex conjugate transpose of matrix A A ^T = transpose of matrix A
|| a || = The norm of the vector a gives the value of a ← b = b to a. The detection result for a˜ = a

As described above, in the present invention, the detection order is determined based on the correlation between the column vectors of the channel matrix H and the norm information of each column vector without calculating the pseudo inverse matrix once. Then, the propagation path matrix in which the column vectors are rearranged is subjected to QR decomposition, and transmission signals are detected in order by one backward substitution using the triangular structure of the R matrix. Therefore, as in the conventional case, the signal detection order is determined and the signal extraction vector is generated in _NT transmission signals by _NT pseudo-inverse matrix calculation, and the transmission signals are detected in order using the extraction vectors. Compared to the method, the required calculation amount is reduced. That is, there are three main operations of the present invention: (1) calculation of correlation between column vectors of channel matrix H, (2) calculation of one QR decomposition, and (3) one backward substitution. . Thereby, the required calculation amount is extremely small as compared with the prior art.

  In addition, since there is no pseudo-matrix operation, the required storage capacity can be reduced. Also, since the circuit scale is proportional to the required amount of computation, the required circuit scale according to the present invention is also very small. In addition, since operations other than backward substitution can be implemented in parallel, processing delay can be suppressed to a very small level, thereby obtaining an effect suitable for signal processing in real time. Based on the above effects, the hardware implementation according to the present invention is extremely feasible. In addition, since the required circuit scale and the capacity of the storage unit can be reduced, it is possible to reduce the size of the device mounted with the conventional technique. In addition, an apparatus using the present invention can be reduced in size, reduced in power consumption, reduced in processing delay, and reduced in manufacturing cost, so that an effect of being suitable for mass production can be obtained.

  The above transmitter and receiver have a computer system inside. The process described above is stored in a computer-readable recording medium in the form of a program, and the above process is performed by the computer reading and executing this program. Here, the computer-readable recording medium means a magnetic disk, a magneto-optical disk, a CD-ROM, a DVD-ROM, a semiconductor memory, or the like. Alternatively, the computer program may be distributed to the computer via a communication line, and the computer that has received the distribution may execute the program.

  The program may be for realizing a part of the functions described above. Furthermore, what can implement | achieve the function mentioned above in combination with the program already recorded on the computer system, and what is called a difference file (difference program) may be sufficient.

It is a block diagram which shows the structure of a radio | wireless communications system. It is a figure which shows the flow of a calculation process of an estimated transmission signal.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10: Transmitter 11: Modulation encoding process part 12-1, 12-2, ..., 12-N _T : Transmitting antenna 20: Receiver 21-1, 21-2, ..., 21-N _T : Transmitting antenna 22: Signal detection processing unit 23: Demodulation decoding processing unit

Claims (13)

The N _T, each transmit radio signals using the same frequency channel (N _T ≧ 2, N _T is an integer) and the transmission device having a transmission antenna, the transmitted radio signal N _R present (N _R ≧ N _T ≧ 2 and N _R is an integer) receiving device, respectively, and the receiving device of a wireless communication system that performs MIMO (Multiple Input Multiple Output) communication,
Signal detection order determining means for determining each signal detection order for the _NT transmission signals;
Channel matrix rearrangement means for rearranging the column vectors of the channel matrix H based on the signal detection order;
Matrix conversion means for performing QR decomposition on the rearranged matrix and converting the matrix into a unitary matrix Q and an upper triangular matrix R;
A reception vector filtering means for filtering the reception vector x using the unitary matrix Q;
A transmission-time radio signal detecting means for detecting each radio signal transmitted from each of the N _T transmit antennas by backward substitution using the upper triangular matrix R and the filtering result;
A receiving apparatus comprising: The signal detection order determining means includes
Calculating the norm of each column vector of the channel matrix H;
Calculating a correlation between each column vector of the channel matrix H;
The receiving apparatus according to claim 1, wherein the signal detection order is determined based on the norm and the correlation. The reception vector filtering means includes:
The reception apparatus according to claim 1, wherein the reception vector x is filtered by multiplying the complex conjugate transpose of the unitary matrix Q and the reception vector x. The transmission radio signal detection means includes:
Using the triangular structure of the upper triangular matrix R, the elements of the received vector obtained by the filtering result are sequentially obtained, and the soft decision result of each element and the hard decision result by quantization of the soft decision result are obtained. The receiving apparatus according to claim 1, wherein each of the radio signals transmitted from each of the N _T transmitting antennas is detected. The N _T, each transmit radio signals using the same frequency channel (N _T ≧ 2, N _T is an integer) and the transmission device having a transmission antenna, the transmitted radio signal N _R present (N _R ≧ Detection of a radio signal transmitted by the transmission device in a wireless communication system that performs MIMO (Multiple Input Multiple Output) communication, and a reception device that receives each of the reception devices with N _T ≧ 2 and N _R is an integer) A method,
The signal detection order determination means of the receiver determines each signal detection order for the _NT transmission signals,
The propagation path matrix rearranging means of the receiving device rearranges the column vectors of the propagation path matrix H based on the signal detection order,
The matrix conversion means of the receiving device performs QR decomposition on the rearranged matrix, converts the matrix into a unitary matrix Q and an upper triangular matrix R,
The reception vector filtering means of the reception device filters the reception vector x using the unitary matrix Q,
The transmission radio signal detection means of the receiver detects each radio signal transmitted from each of the N _T transmit antennas by backward substitution using the upper triangular matrix R and the filtering result. A wireless signal detection method. The signal detection order determining means includes
Calculating the norm of each column vector of the channel matrix H;
Calculating a correlation between each column vector of the channel matrix H;
The radio signal detection method according to claim 5, wherein the signal detection order is determined based on the norm and the correlation. The reception vector filtering means includes:
The radio signal detection method according to claim 5, wherein the reception vector x is filtered by multiplying the complex conjugate transpose of the unitary matrix Q and the reception vector x. The transmission radio signal detection means includes:
Using the triangular structure of the upper triangular matrix R, the elements of the received vector obtained by the filtering result are sequentially obtained, and the soft decision result of each element and the hard decision result by quantization of the soft decision result are obtained. 6. The radio signal detection method according to claim 5, wherein each radio signal transmitted from each of the N _T transmit antennas is detected by obtaining the radio signal. The N _T, each transmit radio signals using the same frequency channel (N _T ≧ 2, N _T is an integer) and the transmission device having a transmission antenna, the transmitted radio signal N _R present (N _R ≧ A program to be executed by a computer of the receiving device in a wireless communication system that performs MIMO (Multiple Input Multiple Output) communication, each of which is received by a receiving device of N _T ≧ 2, N _R is an integer). There,
A signal detection order determination process for determining each signal detection order for the _NT transmission signals;
A channel matrix rearrangement process for rearranging the column vectors of the channel matrix H based on the signal detection order;
A matrix conversion process for performing QR decomposition on the rearranged matrix and converting the matrix into a unitary matrix Q and an upper triangular matrix R;
A reception vector filtering process for filtering the reception vector x using the unitary matrix Q;
Using the upper triangular matrix R and the result of the filtering, a radio signal detection process during transmission for detecting each radio signal transmitted from each of the N _T transmit antennas by backward substitution;
A program that causes a computer to execute. In the signal detection order determination process,
Calculating the norm of each column vector of the channel matrix H;
Calculating a correlation between each column vector of the channel matrix H;
The program according to claim 9, wherein the signal detection order is determined based on the norm and the correlation. The received vector filtering process includes:
The program according to claim 9, wherein the received vector x is filtered by multiplying the complex conjugate transpose of the unitary matrix Q and the received vector x. The transmission radio signal detection process is:
Using the triangular structure of the upper triangular matrix R, the elements of the received vector obtained by the filtering result are sequentially obtained, and the soft decision result of each element and the hard decision result by quantization of the soft decision result are obtained. 10. The program according to claim 9, wherein each of the radio signals transmitted from each of the N _T transmitting antennas is detected. A recording medium for storing the program according to claim 9.

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