JP2006222742A - Transmitting method and transmitter for spatial multiplex transmission - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a transmitter for spatial multiplex transmission which can determine transmission weight by less operation quantity. <P>SOLUTION: In the spatial multiplex transmission transmitter for performing L pieces of spatial multiplex transmission by using N antennas, a transmission coefficient matrix estimation part 170 estimates a transmission coefficient matrix from receiving signals. A transmission weight determination part 180 multiplies a correlation matrix of the transmission coefficient matrix by an estimated transmission weight matrix relative to a propagation environment, finds out an orthogonal vector from a column vector of the obtained matrix and outputs the orthogonal vector to multibeam formation parts 131-13L as transmission weight. A serial-parallel conversion part 110 applies serial-parallel conversion to a transmitting signal and outputs the serial-parallel converted signal to transmission parts 121-12L. The multibeam formation parts 131-13L divide input signals from the transmission parts 121-12L into N signals, apply the weight determined by the transmission weight determination part 180 to the divided signals and then output the weighted signals to corresponding ports of signal composition parts 141-14N. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a transmission method and a transmission apparatus for spatial multiplexing transmission that perform transmission by spatial multiplexing using a plurality of antenna elements.

  The spatial multiplexing transmission apparatus is a transmission apparatus that realizes high-speed transmission without increasing the frequency band by transmitting a plurality of signals from a plurality of antenna elements.

  FIG. 7 shows an ideal spatial multiplexing transmission apparatus that controls transmission directivity so as to be optimal for the propagation environment, performs spatial multiplexing, and improves the transmission rate.

  Reference numeral 910 is a serial-parallel conversion unit, 921 to 92L are transmission units, 931 to 93L are multi-beam forming units, 941 to 94N are signal synthesis units, 951 to 95N are signal switching units, 961 to 96N are antenna elements, and 970 is A transfer coefficient matrix estimation unit 980 is a singular value decomposition calculation unit.

  Signals received by antenna elements 961 to 96N are switched by signal switching units 951 to 95N and output to transmission coefficient matrix estimation unit 970. The transfer coefficient matrix estimation unit 970 calculates a transfer coefficient matrix from the received preamble signal and outputs it to the singular value decomposition calculation unit 980. The singular value decomposition calculation unit 980 performs singular value decomposition on the transfer coefficient matrix and outputs transmission weights to the multi-beam forming units 931 to 93L.

  The transmission signal sequence is distributed to the spatial division multiplexing number L by the serial-parallel conversion unit 910, modulated by the transmission units 921 to 92L, and output to the multi-beam forming units 931 to 93L. Each signal sequence input to the multi-beam forming units 931 to 93L is subjected to transmission weights determined by the transfer coefficient matrix estimation unit 970 and the singular value decomposition calculation unit 980, and then corresponds to the signal synthesis units 941 to 94N. Output to the port. The signal synthesis units 941 to 94N synthesize the input signals, and the output signals are transmitted from the antenna elements 961 to 96N via the signal switching units 951 to 95N.

  Here, the singular value decomposition calculation unit 980 determines the transmission weight applied to the transmission signal by the multi-beam forming units 931 to 93L as follows.

Number of antenna elements of M _T in the spatial multiplexing transmission for transmission _apparatus, the number of antenna elements M _R of a communication partner receiving _apparatus, the M _X a number of smaller one of M _R and M _T. In the transmission apparatus, the transfer coefficient matrix H of the propagation environment in which transmission is performed is estimated. The transfer coefficient matrix H can be expressed by the following equation (1).

In the equation (1), a component H _ij of the transfer coefficient matrix H represents a transfer coefficient between the j-th transmitting antenna and the i-th receiving antenna. The transfer coefficient matrix H is estimated as follows, for example. A preamble signal S ₀ (M _R × M _R matrix), which is known by both the transmission device and the reception device, is transmitted from the reception device to the transmission device, and the preamble is transmitted to the reception signal X ₀ (M _A × M _B ) in the transmission device. can be obtained as the transpose matrix of the inverse matrix ^{_{S 0 -1 (M B × M}} B matrix) matrix obtained by multiplying the signal.

The transfer coefficient matrix H has a unitary matrix V (M _T × M _X matrix), U _U (M _R × M _X matrix) and an eigenvalue √λ as diagonal elements by singular value decomposition shown in the following equation (2). Can be divided into a diagonal matrix D (M _X × M _X diagonal matrix).

In Expression (2), V _ij is a transmission weight applied to the i-th antenna element for the j-th transmission beam in the transmission apparatus, and U _ij is a reception signal of the i-th antenna for the j-th transmission beam of the reception apparatus. It is a complex conjugate of the receiving weight applied to. Here, the eigenvalue λ represents the transmission capacity of each path. The superscript H represents a complex conjugate transpose matrix.

From V obtained in this way, an uplink transmission weight W obtained by selecting a column vector by the spatial multiplexing number L used for communication from a corresponding large eigenvalue is used as a transmission weight of the transmission device, and used from U ^H for communication. The maximum transmission capacity corresponding to the singular value λ can be realized in each signal by using the uplink reception weight W ′ obtained by selecting L row vectors to be used as the reception weight of the reception apparatus. The transmission weight W is shown in the following formula (3), and the reception weight W ′ is shown in the formula (4).

In the case of L = M _X , the transmission apparatus transmits the transmission signal S (M _X × 1 vector) using the transmission weight V, so that the reception signal X (M _R × 1 vector) is expressed by the following (5). It can be expressed as an expression.

Therefore, the transmission signal S can be obtained by multiplying the reception signal X by a complex conjugate transpose matrix of U, for example, to obtain the transmission signal S multiplied by the square root of the corresponding eigenvalue, and each signal has thermal noise N by the eigenvalue λ. The ratio (SN ratio) with respect to the signal becomes high, and communication with the maximum transmission capacity can be realized.
(Miyashita, K .; Nishimura, T .; Ohgane, T .; Ogawa, Y .; Takatori, Y .; KeizoCho; “High data-rate transmission with eigenbeam-space division multiplexing (E-SDM) in a MIMO channel, '' Vehicular Technology Conference, 2002. Proceedings. VTC 2002-Fall. 2002 IEEE 56th, Volume: 3,24-28 Sept. 2002 Pages: 1302_1306 vol.3).

  Although the above means makes it possible to obtain the maximum transmission capacity, there is a problem that the calculation amount of singular value decomposition is large. The present invention has been made in view of such circumstances, and an object of the present invention is to provide a spatial multiplexing transmission method and a spatial multiplexing transmission device capable of realizing communication with a small calculation amount and a high transmission rate. To do.

In order to solve the above-described problems, the transmission method for spatial multiplexing transmission according to the present invention includes a plurality of antenna elements, determines transmission weights using propagation environment information, performs transmission weights on transmission signals, and is the same. A method of transmitting a plurality of signal sequences at the same frequency in time, in which a transmission coefficient matrix is estimated from a received signal at a transmitting station or a receiving station, and each is a product of a complex conjugate transpose matrix and a transmission coefficient matrix of the transmission coefficient matrix. A certain correlation matrix is calculated, the matrix subjected to the calculation in the correlation matrix is multiplied, an orthogonal vector obtained by using an orthogonalization method is calculated for the column vector component of the obtained matrix, and the calculated An orthogonal vector is used as a transmission weight in the transmission station.
As a result, the amount of calculation required to determine the transmission weight can be reduced, and communication with a high transmission rate can be realized.

In addition, the spatial multiplexing transmission method of the present invention estimates the transmission quality of each stream from the norm value of the column vector of the matrix obtained when multiplying the matrix on which the operation in the correlation matrix is performed, It is characterized by determining a modulation scheme and power distribution.
As a result, the amount of calculation required to determine the transmission weight can be reduced, and communication with a high transmission rate can be realized.

Also, the spatial multiplexing transmission method of the present invention is characterized in that the matrix subjected to the certain operation is an estimated transmission weight matrix having a correlation with a theoretically optimal transmission weight in the propagation environment.
As a result, the amount of calculation required to determine the transmission weight can be reduced, and communication with a high transmission rate can be realized.

The spatial multiplexing transmission method of the present invention is characterized in that the matrix subjected to the certain calculation is a transmission weight matrix used at the time of past transmission.
As a result, the amount of calculation required to determine the transmission weight can be reduced, and communication with a high transmission rate can be realized.

In addition, the transmission method for spatial multiplexing transmission of the present invention uses orthogonal wave frequency division multiplexing to estimate a transfer coefficient matrix in each frequency band from a received signal when transmitting different signal sequences in a plurality of frequency bands. Calculating the correlation matrix, which is the product of the complex conjugate transpose matrix of the transfer coefficient matrix and the transfer coefficient matrix, calculating the eigenvector of the correlation matrix in an arbitrary frequency band, and using the obtained transmission weight matrix as the estimated transmission weight matrix. An orthogonal vector obtained by multiplying a correlation matrix of a neighboring frequency band and using an orthogonalization method for a column vector component of the obtained matrix is used as a transmission weight of the frequency band.
As a result, the amount of calculation required to determine the transmission weight can be reduced, and communication with a high transmission rate can be realized.

Also, the spatial multiplexing transmission method of the present invention estimates a transfer coefficient matrix from a received signal, calculates a correlation matrix that is the product of a complex conjugate transpose matrix of the transfer coefficient matrix and the transfer coefficient matrix, and generates a complex of the transfer coefficient matrix. A correlation transpose matrix or an inverse matrix is multiplied by a conjugate transpose matrix, and an orthogonal vector obtained by using an orthogonalization method for a column vector component of the obtained matrix is used as a transmission weight.
As a result, the amount of calculation required to determine the transmission weight can be reduced, and communication with a high transmission rate can be realized.

Also, the spatial multiplexing transmission method of the present invention estimates a transfer coefficient matrix from a received signal, calculates a correlation matrix that is the product of a complex conjugate transpose matrix of the transfer coefficient matrix and the transfer coefficient matrix, and generates a complex of the transfer coefficient matrix. Multiply the correlation matrix by the matrix obtained by using the orthogonalization method for the column vector of the conjugate transpose matrix or the inverse matrix, and transmit the orthogonal vector obtained by using the orthogonalization method for the column vector component of the obtained matrix It is characterized by a weight.
As a result, the amount of calculation required to determine the transmission weight can be reduced, and communication with a high transmission rate can be realized.

Also, the spatial multiplexing transmission method of the present invention estimates a transfer coefficient matrix from a received signal, calculates a correlation matrix that is the product of a complex conjugate transpose matrix of the transfer coefficient matrix and the transfer coefficient matrix, The matrix obtained by using the orthogonalization method for the column vector of the inverse matrix is multiplied by the correlation matrix, and the orthogonal vector obtained by using the orthogonalization method for the column vector component of the obtained matrix is used as the transmission weight. Features.
As a result, the amount of calculation required to determine the transmission weight can be reduced, and communication with a high transmission rate can be realized.

Also, the spatial multiplexing transmission method of the present invention multiplies the correlation matrix by orthogonalizing it to any one of the complex conjugate transpose matrix, inverse matrix, correlation matrix, or inverse matrix of the transfer coefficient matrix. When the method is used, orthogonalization is performed in descending order of the norm of the column vector.
As a result, the amount of calculation required to determine the transmission weight can be reduced, and communication with a high transmission rate can be realized.

In addition, the spatial multiplexing transmission method of the present invention can multiply the correlation matrix again by the transmission weight matrix composed of the obtained transmission weights, and use the orthogonalization method for the column vector of the obtained matrix any number of times. And the obtained orthogonal vector is used as a transmission weight.
As a result, the amount of calculation required to determine the transmission weight can be reduced, and communication with a high transmission rate can be realized.

In addition, the spatial multiplexing transmission apparatus of the present invention is a spatial multiplexing transmission apparatus that uses N antenna elements and performs transmission by L spatial multiplexing, and is connected to each antenna element to transmit a received signal and a transmission A signal switching unit that switches signals, a transmission coefficient matrix estimation unit that estimates a transfer coefficient matrix using a signal output from the signal switching unit during reception as an input signal, and the transfer coefficient matrix estimation A correlation matrix that is a product of the complex conjugate transposed matrix of the transfer coefficient matrix estimated by the block and the transfer coefficient matrix, and outputs the correlation matrix to the matrix multiplication calculation section, and a matrix that is correlated with the eigenvector matrix of the correlation matrix And the estimated transmission weight matrix storage unit for output to the matrix multiplication operation unit, the correlation matrix input from the correlation matrix calculation unit, and the input from the estimated transmission weight matrix storage unit A matrix multiplication operation unit that multiplies the estimated weight matrix and an orthogonalization operation on each column vector of the matrix calculated in the matrix multiplication operation unit, and outputs the obtained orthogonal vector to the multi-beam forming unit as a transmission weight An orthogonalization calculation unit, a correlation matrix calculation unit, an estimated transmission weight matrix storage unit, a matrix multiplication calculation unit, a transmission weight determination unit consisting of an orthogonalization calculation unit, serial-parallel conversion on the input signal to be transmitted, and a space A serial-parallel conversion unit that distributes the signals to a multiplexing number L, a transmission unit that outputs an output signal of the serial-parallel conversion unit as an input signal and outputs a transmission signal sequence to a multi-beam forming unit, and a signal input from the transmission unit The input signal is divided into N signals, weighted as determined by the transmission weight determining unit, and then output to the corresponding ports of the N signal combining units. A signal for superimposing signals output to L ports from the corresponding L multi-beam forming units among the multi-beam forming unit and the multi-beam forming unit, and outputting the signal to the other port of the signal switching unit And a combining unit.
As a result, the amount of calculation required to determine the transmission weight can be reduced, and communication with a high transmission rate can be realized.

Further, in the spatial multiplexing transmission apparatus of the present invention, in the transmission weight determining unit, the estimated transmission weight matrix storage unit is a transmission weight matrix used in the past or a transmission weight in a neighboring frequency band in orthogonal frequency division multiplexing. It is characterized by memorizing a matrix.
As a result, the amount of calculation required to determine the transmission weight can be reduced, and communication with a high transmission rate can be realized.

In the spatial multiplexing transmission apparatus of the present invention, the transmission weight determination unit uses the transfer coefficient matrix estimated by the transfer coefficient matrix estimation unit as an input signal, and includes a complex conjugate transpose matrix, an inverse matrix, a correlation matrix, and a correlation An operation for obtaining one of the inverse matrixes is performed, a matrix operation unit that outputs to the first orthogonal operation unit, an orthogonal operation is performed on the matrix input from the matrix operation unit, and the matrix multiplication operation unit A first orthogonalization calculation unit that outputs, a correlation matrix calculation unit that calculates a correlation matrix using the transfer coefficient matrix estimated in the transfer coefficient matrix estimation unit as an input signal, and a correlation matrix input from the correlation matrix calculation unit And a matrix multiplication operation unit that multiplies the matrix input from the first orthogonalization operation unit and outputs to the second orthogonalization operation unit, and a matrix input from the matrix multiplication operation unit as an input signal, Pair to matrix column vector Calculating an orthogonal Bekuru using orthogonalization method, a second orthogonalization arithmetic unit for outputting the multi-beam forming unit obtained orthogonal vectors as transmission weights, comprising the to.
As a result, the amount of calculation required to determine the transmission weight can be reduced, and communication with a high transmission rate can be realized.

In the spatial multiplexing transmission apparatus according to the present invention, the transmission weight determination unit further repeats an operation of multiplying the calculated transmission weight matrix by a correlation matrix and performing an orthogonalization operation on the obtained matrix any number of times. Means for outputting the obtained orthogonal vector as a transmission weight to the multi-beam forming unit.
As a result, the amount of calculation required to determine the transmission weight can be reduced, and communication with a high transmission rate can be realized.

  In the spatial multiplexing transmission method of the present invention, a transfer coefficient matrix is estimated from a received signal, a correlation matrix is calculated from the transfer coefficient matrix, and a matrix obtained by performing an operation on the correlation matrix is multiplied. Since the orthogonal vector obtained by using the orthogonalization method for the column vector component is used as the transmission weight at the transmitting station, this reduces the amount of computation required to determine the transmission weight and increases the transmission. Communication with speed can be realized.

  Further, in the spatial multiplexing transmission method of the present invention, the transmission quality of each stream is estimated from the value of the norm of the column vector of the matrix obtained when multiplying the matrix subjected to the operation in the correlation matrix, Since the modulation scheme and the power distribution are determined, this reduces the amount of calculation required to determine the transmission weight and can realize communication with a high transmission rate.

  Further, in the spatial multiplexing transmission method of the present invention, the matrix subjected to a certain calculation is an estimated transmission weight matrix that correlates with a theoretically optimal transmission weight in the propagation environment. The amount of calculation required to determine the transmission weight can be reduced, and communication with a high transmission rate can be realized.

  In addition, in the spatial multiplexing transmission method of the present invention, the matrix on which a certain operation has been performed is the transmission weight matrix used at the time of past transmission, so that it is necessary to determine the transmission weight. The amount of computation can be reduced and communication with a high transmission rate can be realized.

  In addition, in the transmission method for spatial multiplexing transmission according to the present invention, when orthogonal signal frequency division multiplexing is used and different signal sequences are transmitted in a plurality of frequency bands, the correlation matrix of the transfer coefficient matrix of each frequency is calculated. In addition, the eigenvector of the correlation matrix is calculated in an arbitrary frequency band, the obtained transmission weight matrix is multiplied by the correlation matrix of the neighboring frequency band as the estimated transmission weight matrix, and orthogonalized to the column vector component of the obtained matrix Since the orthogonal vector obtained by using the method is used as the transmission weight of the frequency band, it is possible to reduce the amount of calculation necessary for determining the transmission weight and realize communication with a high transmission rate.

  In the spatial multiplexing transmission method of the present invention, the correlation matrix of the transfer coefficient matrix is calculated, the complex conjugate transpose matrix or inverse matrix of the transfer coefficient matrix is multiplied by the correlation matrix, and the obtained column vector component is obtained. On the other hand, since the orthogonal vector obtained by using the orthogonalization method is used as the transmission weight, the amount of calculation required for determining the transmission weight can be reduced, and communication with a high transmission rate can be realized.

  In the spatial multiplexing transmission method of the present invention, the correlation matrix of the transfer coefficient matrix is calculated, and the matrix obtained by using the orthogonalization method is correlated with the complex conjugate transpose matrix or the inverse matrix of the transfer coefficient matrix. Since the matrix is multiplied and the orthogonal vector obtained by using the orthogonalization method is used as the transmission weight for the column vector component of the obtained matrix, this reduces the amount of computation required to determine the transmission weight In addition, communication with a high transmission rate can be realized.

  In the spatial multiplexing transmission method of the present invention, the correlation matrix of the transfer coefficient matrix is calculated, and the correlation matrix or the matrix obtained by using the orthogonalization method is multiplied to the correlation matrix or the inverse matrix of the correlation matrix by the correlation matrix. Since the orthogonal vector obtained by using the orthogonalization method is used as the transmission weight for the column vector component of the obtained matrix, this reduces the amount of calculation required to determine the transmission weight, and the high Communication with transmission speed can be realized.

  Also, in the spatial multiplexing transmission method of the present invention, the correlation matrix is multiplied by a complex conjugate transpose matrix of the transfer coefficient matrix, an inverse matrix, a correlation matrix, or a matrix vector orthogonal to the correlation matrix. When using the conversion method, orthogonalization is performed in descending order of the norm of the column vector, thereby reducing the amount of computation required to determine the transmission weight and realizing communication with a high transmission rate. it can.

  In the spatial multiplexing transmission method according to the present invention, the transmission weight matrix composed of the transmission weights obtained by the operation is multiplied again by the correlation matrix, and the column vector of the obtained matrix is orthogonalized using the orthogonalization method. Since the vector acquisition operation is repeated any number of times and the obtained orthogonal vector is used as the transmission weight, this reduces the amount of computation required to determine the transmission weight and allows communication with a high transmission rate. realizable.

  Further, in the spatial multiplexing transmission apparatus of the present invention, the transmission weight determination unit calculates a correlation matrix of the transfer coefficient matrix, multiplies the correlation matrix by the estimated weight matrix, and applies each column vector of the obtained matrix to Since the orthogonalization operation is performed and the obtained orthogonal vector is output as a transmission weight to the multi-beam forming unit, this reduces the amount of calculation necessary to determine the transmission weight and increases the transmission rate. Communication can be realized.

  In the spatial multiplexing transmission apparatus according to the present invention, the estimated transmission weight matrix storage unit may use a transmission weight matrix used in the past or a transmission weight matrix in a neighboring frequency band in orthogonal frequency division multiplexing as an estimated weight matrix. Thus, the amount of calculation required to determine the transmission weight can be reduced, and communication with a high transmission rate can be realized.

  In the spatial multiplexing transmission apparatus of the present invention, the transmission weight determination unit obtains one of a complex conjugate transpose matrix, an inverse matrix, a correlation matrix, and an inverse matrix of the correlation matrix of the transfer coefficient matrix to perform an orthogonalization operation. The matrix obtained by this orthogonalization operation is multiplied by the correlation matrix, and the orthogonalization is performed on the column vector of the matrix of the multiplication result to determine the transmission weight. It is possible to reduce the amount of calculation required to achieve communication with high transmission speed.

  In the spatial multiplexing transmission apparatus of the present invention, the transmission weight determination unit further repeats the operation of multiplying the calculated transmission weight matrix by the correlation matrix and performing the orthogonalization operation on the obtained matrix any number of times. Since it did in this way, the amount of calculations required in order to determine a transmission weight can be reduced by this, and communication with a high transmission rate is realizable.

Hereinafter, an embodiment of the present invention will be described in detail with reference to FIG.
FIG. 1 is a block diagram showing a configuration example of a spatial multiplexing transmission apparatus according to the present invention. In the case of performing communication for obtaining high transmission quality by transmission directivity control that is optimal for a propagation environment, transmission weights are simplified. The structure which enables it to be determined is shown.

  In FIG. 1, reference numeral 110 is a serial-parallel converter, 121 to 121 are transmitters, 131 to 13L are multi-beam forming units, 141 to 14N are signal synthesizers, 151 to 15N are signal switching units, and 161 to 16N are antennas. An element, 170 is a transfer coefficient matrix estimation unit, 180 is a transmission weight determination unit, 181 is a correlation matrix calculation unit, 182 is a matrix multiplication calculation unit, 183 is an orthogonalization calculation unit, and 184 is an estimated transmission weight matrix storage unit.

  Signals received by the antenna elements 161 to 16N are switched by the signal switching units 151 to 15N and output to the transfer coefficient matrix estimation unit 170. The transmission coefficient matrix estimation unit 170 calculates a transmission coefficient matrix from the received preamble signal and outputs it to the correlation matrix calculation unit 181 of the transmission weight determination unit 180. The correlation matrix calculation unit 181 obtains a correlation matrix that is the product of the complex conjugate transpose matrix of the transfer coefficient matrix and the transfer coefficient matrix. The estimated transmission weight matrix storage unit 184 stores an estimated transmission weight matrix correlated with the transmission weight, and the matrix multiplication operation unit 182 stores the correlation matrix input from the correlation matrix operation unit 181 and the estimated transmission weight matrix. The estimated transmission weight matrix input from the storage unit 184 is multiplied, and the obtained matrix is output to the orthogonalization calculation unit 183. The orthogonalization calculation unit 183 determines the transmission weight and outputs the transmission weight to the multi-beam forming units 131 to 13L.

  The transmission signal sequence is distributed to the spatial division multiplexing number L by the serial-parallel conversion unit 110, modulated by the transmission units 121 to 12L, and output to the multi-beam forming units 131 to 13L. Each signal sequence input to the multi-beam forming units 131 to 13L is multiplied by the transmission weight determined by the transmission weight determination unit 180 by an analog or digital quantity, and then is sent to the corresponding port of the signal synthesis units 141 to 14N. Is output. The signal synthesis units 141 to 14N synthesize the input signals, and the output signals are transmitted from the antenna elements 161 to 16N via the signal switching units 151 to 15N.

  For simplicity, let us consider communication when the number of antenna elements of the receiving apparatus is M and the number of antenna elements of the spatial multiplexing transmission apparatus is N (N ≧ M).

The spatial multiplexing transmission apparatus estimates the transfer coefficient matrix H by receiving a known signal, utilizing feedback information, or the like. The correlation matrix calculation unit 181 multiplies the complex conjugate transpose matrix H ^H of the transfer coefficient matrix and the transfer coefficient matrix H to calculate the correlation matrix R. This correlation matrix R is expressed by the following equation (6).

  The matrix multiplication operation unit 182 multiplies the correlation matrix R and the estimated weight matrix V ′ correlated with the theoretically optimal transmission weight matrix V output from the estimated transmission weight matrix storage unit 184. The resulting matrix R ′ is expressed by the following equation (7).

  In the matrix R ′ shown in the equation (7), α> β is satisfied because V and V ′ have a correlation. Therefore, the matrix R ′ obtained here has a high correlation with V.

In the orthogonalization calculation unit 183, the R ′ column vectors r ₁ ′ to r _M ′ are made closer to ideal transmission weights by using the orthogonalization method. The column vectors selected here are denoted by r ₁ ′, r ₂ ′,..., R _M ′, and the inner product of the vectors a and b is represented by (a, b). When w ₁ = r ′ ₁ and the Gram Schmitt orthogonalization method shown in the equation (8) is performed, orthogonal vectors w ₁ , w ₂ ,..., w _M can be obtained.

These orthogonal vectors w ₁ , w ₂ ,..., W _M have a high correlation with the ideal transmission weight given by equation (3). Therefore, by outputting these vectors as transmission weights to the multi-beam forming units 131 to 13L, a high transmission capacity can be realized without performing a process with a large calculation such as singular value decomposition.

  The estimated weight matrix V ′ correlated with the optimal transmission weight matrix V includes transmission weights used in the past, complex conjugate transpose matrix of transfer coefficient matrix, inverse matrix of transfer coefficient matrix, and orthogonal wave frequency division multiplexing. When used, the transmission weight obtained in the neighboring frequency band can be used.

  Next, another configuration example of the transmission weight determination unit 180 will be described. FIG. 2 is a block diagram showing another configuration example of the transmission weight determination unit of the spatial multiplexing transmission apparatus of the present invention. In FIG. 2, reference numeral 281 denotes a correlation matrix calculation unit, reference numeral 282 denotes a matrix multiplication calculation unit, reference numeral 283 denotes an orthogonalization calculation unit (second orthogonalization calculation unit), reference numeral 284 denotes a matrix calculation unit, and reference numeral 285 denotes an orthogonalization calculation. Part (first orthogonalization operation part).

  Using the transfer coefficient matrix estimated by the transfer coefficient matrix estimation unit 170 as an input signal, the correlation matrix calculation unit 281 and the matrix calculation unit 284 respectively calculate the correlation matrix of the transfer coefficient matrix and the complex conjugate transpose matrix of the transfer coefficient matrix. The orthogonalization calculation unit 285 outputs a matrix using an orthogonalization method to the matrix multiplication calculation unit 282 for each column vector of the matrix output from the matrix calculation unit 284, and the matrix multiplication calculation unit 282 outputs a correlation matrix calculation. The correlation matrix calculated by the unit 281 is multiplied by the matrix input by the orthogonalization calculation unit 285, and the obtained matrix is output to the orthogonalization calculation unit 283. In the orthogonalization calculation unit 283, the matrix of the input matrix is output. Each column vector is orthogonalized and output as a transmission weight to the multi-beam forming unit.

The complex conjugate transpose matrix H ^H of the transfer coefficient matrix H obtained in the matrix calculation unit 284 can be expressed as the following equation (9).

The relation √λ ₁ > √λ ₂ >...> √λ _M holds for the eigenvalue √λ of the complex conjugate transpose matrix H ^H shown in equation (9), and the column vector of the complex conjugate transpose matrix H ^H is It can be expected to have a correlation with the first eigenvector corresponding to the maximum eigenvalue of the ideal transmission weight matrix V. Therefore, a matrix having a high correlation with the ideal transmission weight matrix V can be obtained by performing orthogonalization on each column vector of this matrix. By multiplying such a matrix by the correlation matrix in the matrix multiplication operation unit 282, the same effect as the expression (7) can be expected. Therefore, it is possible to realize communication with transmission weights that achieve a high transmission capacity without performing singular value decomposition.

In addition, in the matrix calculation unit 284, the effect can be expected even if any of the inverse matrix of the transfer coefficient matrix, the correlation matrix, and the inverse matrix of the correlation matrix is used as the matrix to be calculated. The inverse matrix H ⁻¹ of the transfer coefficient matrix is shown in the following expression (10), the phase correlation matrix H ^H H is shown in the expression (11), and the inverse matrix (H ^H H) ⁻¹ of the correlation matrix is expressed in the expression (12). Shown in

In the equations (10), (11), and (12), the eigenvalue √λ has a √λ ₁ > √λ ₂ >...> √λ _M relationship, and the inverse matrix of the transfer coefficient matrix, and Regarding the inverse matrix of the correlation matrix, the column vector is highly correlated with the eigenvector corresponding to the smallest eigenvalue of the ideal transmission weight matrix V, and the column vector of the correlation matrix is the first eigenvector of the ideal transmission weight matrix V. It can be expected that the correlation will be high. Therefore, a matrix highly correlated with the ideal transmission weight matrix V can be obtained by performing orthogonalization on each column vector of any of these matrices. By multiplying such a matrix by the correlation matrix in the matrix multiplication operation unit 282, the same effect as the expression (7) can be expected. Therefore, it is possible to realize communication with transmission weights that achieve a high transmission capacity without performing singular value decomposition.

  Also, the complex conjugate transpose matrix of the transfer coefficient matrix, the inverse matrix, the correlation matrix, the inverse matrix of the correlation matrix, and the matrix multiplied by an ideal transmission weight matrix and a matrix that seems to be highly correlated When the orthogonalization method is used, by applying the column vector having the largest norm, a more obtained result can be approximated to an ideal transmission weight matrix.

  Note that the orthogonalization calculation unit 285 and the orthogonalization calculation unit 283 in FIG. 2 can be the same, and the matrix calculation unit 284 is a correlation matrix calculation unit 281 in the case of calculating a correlation matrix. This function can be shared in common.

  The orthogonalization operation unit 183 in FIG. 1 can output the output result to the matrix multiplication operation unit 182. Further, the orthogonalization calculation unit 283 in FIG. 2 can output the output result to the matrix multiplication calculation unit 282. By multiplying the correlation matrix again in the matrix multiplication operation unit 182 or 282, a matrix closer to the ideal transmission weight is output to the orthogonalization operation unit 183 or 283, and further orthogonalized, thereby further increasing the transmission capacity. The realized transmission weight matrix can be output to the multi-beam forming unit. Further, the transmission capacity can be further increased by outputting the obtained matrix again to the matrix multiplication operation unit 182 or 282 and repeating the same processing a plurality of times.

In the matrix multiplication operation unit 182 or 282, a matrix R ′ obtained when the correlation matrix is multiplied by an ideal transmission weight matrix and a matrix having a correlation is as shown in Equation (7). The norm of this column vector is It takes a value close to λ _{1 to} λ _M which is the square of the eigenvalue. Communication using the transmission weight matrix V can obtain a signal-to-noise ratio corresponding to the eigenvalue as described above. Therefore, the value of the norm of the column vector of this matrix R can be used for the modulation scheme applied in communication using a certain transmission weight and the value of power distribution. For example, modulation schemes such as 256QAM, 64QAM, 16QAM, QPSK, BPSK, etc. An appropriate modulation method can be selected from the above.

  In the singular value decomposition, when an eigenvector is obtained by an iterative operation such as the power method or the QR method, an estimated transmission weight matrix obtained in advance by which the correlation matrix is multiplied is used as an initial value, and the number of iterations until convergence is accelerated. Thus, the amount of calculation can be reduced.

  Next, the effect of the spatial multiplexing transmission apparatus according to the present invention will be described with a specific example. When the number of transmitting elements is 4 and the number of receiving elements is 4 in the spatial multiplexing transmission apparatus, a correlation matrix obtained by performing orthogonalization operation on the column vector of the inverse matrix of the transfer coefficient matrix from the one having a large norm The transmission capacity when the transmission weight is obtained by multiplying the obtained matrix column vector and performing orthogonalization again on the column vector of the obtained matrix, and the non-directional transmission without applying the transmission weight, and ( Comparison is made with the ideal value to which the ideal transmission weight given by equation (3) is applied.

  The propagation environment used in order to verify the effect of the directivity control method by this invention is shown. As shown in FIG. 3, six clusters from No. 1 to No. 6 (# 1 to # 6) were installed around the transmitting station and the receiving station, respectively, with a Laplacian distribution and an angle spread of 25 °. The incoming waves were 90 waves, and 15 waves were divided into groups from No. 1 to No. 6.

  FIG. 4 shows a graph representing the incoming wave power and arrival time. Each group of incoming waves has a 50% probability of passing through the same number of clusters installed around the base station and the terminal station, and a 10% probability of passing through the other numbered clusters.

  The propagation parameters applied to each incoming wave group are shown in FIG. The delay spread for the entire incoming wave is 61 nsec. The carrier frequency was 5.2 GHz, the frequency band of each subcarrier was 0.31 MHz, and the number of subcarriers was 50. It is assumed that equal power is allocated to each beam, and the MMSE algorithm is used for decoding.

  Using the propagation environment model as described above, the cluster, the scatterers constituting it, and the phase of each incoming wave are randomly assigned, and trials are performed 100 times. The total number of subcarriers (50) × number of trials (100) Was used to calculate the cumulative probability of the transmission capacity. The result is shown in FIG. According to FIG. 5, it was shown that the deterioration amount from the ideal value is about 0.4% lower than the 50% value of the cumulative probability.

  As described above, in the transmitter for spatial multiplexing transmission of the present invention, it is possible to determine the transmission weight without performing calculation of singular value decomposition with a large calculation load, thereby reducing the amount of calculation, In addition, high transmission quality can be obtained.

    Although the embodiments of the present invention have been described above, the spatial multiplexing transmission apparatus of the present invention is not limited to the above-described illustrated examples, and various modifications can be made without departing from the scope of the present invention. Of course, it can be added.

  According to the present invention, in communication using space division multiplexing by singular value decomposition, it is possible to determine the transmission weight by a simple calculation and realize communication with a high transmission rate. This is useful for a transmission method for transmission and a transmission apparatus for spatial multiplexing transmission.

It is a block diagram which shows the structural example of the transmitter for spatial multiplexing transmission of this invention. It is a block diagram which shows the other structural example of the transmission weight determination part of the transmitter for spatial multiplexing transmission. It is a figure which shows the propagation environment used for computer simulation. It is a figure which shows the electric power distribution of the incoming elementary wave used for computer simulation. It is a figure which shows the cumulative probability of the transmission capacity which shows the effect of this invention. It is a figure which shows the propagation parameter of an incoming wave group. 1 is a block diagram showing an ideal spatial multiplexing transmission apparatus. FIG.

Explanation of symbols

110, 910 Serial-parallel converters 121-12L, 921-92L Transmitters 131-13L, 931-93L Multi-beam forming units 141-14N, 941-94N Signal combiners 151-15N, 951-95N Signal switching unit 161 16N, 961-96N Antenna elements 170, 970 Transfer coefficient matrix estimation unit 181, 281 Correlation matrix calculation unit 182, 282 Matrix multiplication calculation unit 183, 283, 285 Orthogonalization calculation unit 184 Estimated transmission weight matrix storage unit 284 Matrix calculation unit 980 Singular value decomposition calculation unit

Claims (14)

A method comprising a plurality of antenna elements, determining a transmission weight using propagation environment information, performing transmission weighting on a transmission signal, and transmitting a plurality of signal sequences at the same time and at the same frequency,
At the transmitting or receiving station,
Estimate the transfer coefficient matrix from the received signal, calculate the correlation matrix that is the product of the complex conjugate transpose matrix and the transfer coefficient matrix of each transfer coefficient matrix,
Multiplying the matrix subjected to the operation in the correlation matrix, calculating an orthogonal vector obtained by using an orthogonalization method for the column vector component of the obtained matrix,
A transmission method for spatial multiplexing transmission, wherein the calculated orthogonal vector is used as a transmission weight in a transmission station. The transmission quality of each stream is estimated from the norm value of the column vector of the matrix obtained by multiplying the matrix subjected to the operation in the correlation matrix, and the modulation scheme and power distribution are determined. The transmission method for spatial multiplexing transmission according to claim 1. 3. The spatial multiplexing transmission method according to claim 1, wherein the matrix subjected to the certain calculation is an estimated transmission weight matrix having a correlation with a transmission weight that is theoretically optimal in a propagation environment. The transmission method for spatial multiplexing transmission according to claim 1 or 2, wherein the matrix subjected to the certain calculation is a transmission weight matrix used at the time of past transmission. When using orthogonal frequency division multiplexing and transmitting different signal sequences in multiple frequency bands,
From the received signal, estimate the transfer coefficient matrix in each frequency band, calculate the correlation matrix that is the product of the complex conjugate transpose matrix of the transfer coefficient matrix and the transfer coefficient matrix,
Calculate the eigenvector of the correlation matrix in an arbitrary frequency band, multiply the obtained transmission weight matrix as the estimated transmission weight matrix by the correlation matrix of the neighboring frequency band, and use the orthogonalization method for the column vector components of the obtained matrix The transmission method for spatial multiplexing transmission according to claim 1 or 2, wherein the orthogonal vector obtained by this is used as a transmission weight of the frequency band. Estimate the transfer coefficient matrix from the received signal, calculate the correlation matrix that is the product of the complex conjugate transpose matrix of the transfer coefficient matrix and the transfer coefficient matrix,
The transmission weight is an orthogonal vector obtained by multiplying a correlation matrix by a complex conjugate transpose matrix or an inverse matrix of a transfer coefficient matrix, and using an orthogonalization method on a column vector component of the obtained matrix. The transmission method for spatial multiplexing transmission according to claim 1 or 2. Estimate the transfer coefficient matrix from the received signal, calculate the correlation matrix that is the product of the complex conjugate transpose matrix of the transfer coefficient matrix and the transfer coefficient matrix,
Obtained by multiplying the correlation matrix by the matrix obtained by using the orthogonal conjugate method for the complex conjugate transpose matrix of the transfer coefficient matrix or the column vector of the inverse matrix, and using the orthogonalization method for the column vector components of the resulting matrix The transmission method for spatial multiplexing transmission according to claim 1 or 2, wherein an orthogonal vector to be transmitted is used as a transmission weight. Estimate the transfer coefficient matrix from the received signal, calculate the correlation matrix that is the product of the complex conjugate transpose matrix of the transfer coefficient matrix and the transfer coefficient matrix,
Multiply the correlation matrix by the matrix obtained by using the orthogonalization method on the correlation matrix or its inverse matrix column vector, and transmit the orthogonal vector obtained by using the orthogonalization method for the column vector component of the obtained matrix The transmission method for spatial multiplexing transmission according to claim 1 or 2, wherein a weight is used. When the orthogonalization method is used for the column vector of one of the complex conjugate transpose matrix, inverse matrix, correlation matrix, or inverse matrix of the transfer coefficient matrix that multiplies the correlation matrix, the column vector with a large norm The transmission method for spatial multiplexing transmission according to claim 7 or 8, wherein the orthogonalization is performed in order. Multiply the correlation matrix again by the transmission weight matrix consisting of the transmission weights obtained,
The transmission method for spatial multiplexing transmission according to claim 1, wherein the orthogonalization method is used an arbitrary number of times for the column vector of the obtained matrix, and the obtained orthogonal vector is used as a transmission weight. In a spatial multiplexing transmission apparatus that performs transmission by L spatial multiplexing using N antenna elements,
A signal switching unit that is connected to each antenna element and switches between a reception signal and a transmission signal;
A transfer coefficient matrix estimation unit that is connected to the signal switching unit and receives a signal output from the signal switching unit at the time of reception as an input signal, and estimates a transfer coefficient matrix;
A correlation matrix calculation unit that calculates a correlation matrix that is a product of a complex conjugate transpose matrix and a transfer coefficient matrix of the transfer coefficient matrix estimated in the transfer coefficient matrix estimation unit, and outputs the correlation matrix to the matrix multiplication calculation unit;
An estimated transmission weight matrix storage unit that stores a matrix correlated with the eigenvector matrix of the correlation matrix and outputs the matrix to the matrix multiplication operation unit;
A matrix multiplication operation unit that multiplies the correlation matrix input from the correlation matrix operation unit by the estimated weight matrix input from the estimated transmission weight matrix storage unit;
An orthogonalization operation unit that performs orthogonalization operation on each column vector of the matrix calculated in the matrix multiplication operation unit, and outputs the obtained orthogonal vector as a transmission weight to the multi-beam forming unit;
A transmission weight determination unit comprising the correlation matrix calculation unit, an estimated transmission weight matrix storage unit, a matrix multiplication calculation unit, and an orthogonalization calculation unit;
A serial-parallel converter that performs serial-parallel conversion on an input signal to be transmitted and distributes the input signal to a spatial multiplexing number L;
An output signal of the serial-parallel conversion unit as an input signal, and a transmission unit that outputs a transmission signal sequence to a multi-beam forming unit;
The signal input from the transmission unit is used as an input signal, divided into N signals, weighted by the transmission weight determination unit, and then output to the corresponding ports of the N signal synthesis units A multi-beam forming unit;
Among the multi-beam forming units, a signal combining unit that superimposes the signals output from the corresponding L multi-beam forming units to L ports and outputs the signals to the other port of the signal switching unit;
A spatial multiplexing transmission apparatus characterized by comprising: In the transmission weight determination unit,
12. The transmission for spatial multiplexing transmission according to claim 11, wherein the estimated transmission weight matrix storage unit stores a transmission weight matrix used in the past or a transmission weight matrix in a neighboring frequency band in orthogonal frequency division multiplexing. apparatus. The transmission weight determination unit
Using the transfer coefficient matrix estimated by the transfer coefficient matrix estimation unit as an input signal, an operation for obtaining any one of a complex conjugate transpose matrix, an inverse matrix, a correlation matrix, and an inverse matrix of a correlation matrix is performed, and a first orthogonalization operation is performed. A matrix calculation unit to output to the unit,
A first orthogonalization operation unit that performs an orthogonalization operation on the matrix input from the matrix operation unit and outputs the matrix to the matrix multiplication operation unit;
A correlation matrix calculation unit for calculating a correlation matrix using the transfer coefficient matrix estimated in the transfer coefficient matrix estimation unit as an input signal;
A matrix multiplication operation unit that multiplies the correlation matrix input from the correlation matrix operation unit by the matrix input from the first orthogonalization operation unit, and outputs the result to the second orthogonalization operation unit;
A matrix input from the matrix multiplication operation unit is used as an input signal, an orthogonal vector is calculated by using an orthogonalization method for the column vector of the matrix, and the obtained orthogonal vector is output to the multi-beam forming unit as a transmission weight. Two orthogonalization calculators;
The transmitter for spatial multiplexing transmission according to claim 11, comprising: The transmission weight determination unit
The calculated transmission weight matrix is further multiplied by the correlation matrix, and the means for repeating the operation of orthogonalizing the obtained matrix is repeated any number of times, and the obtained orthogonal vector is output to the multi-beam forming unit as the transmission weight. The transmitter for spatial multiplexing transmission according to claim 11.

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