JP5008702B2 - Spatial multiplexing transmission method and spatial multiplexing transmission apparatus - Google Patents

Description

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

A spatial multiplexing transmission apparatus (also simply referred to as “transmission apparatus”) transmits a different signal from a plurality of antenna elements, thereby realizing high-speed transmission without increasing the frequency range. It is.
FIG. 7 shows an ideal transmitter for spatial multiplexing transmission that controls transmission directivity so as to be optimal for the propagation environment and performs spatial multiplexing to improve the transmission speed. In FIG. 7, 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 switching units, and 961 to 96N are antenna elements. , 970 is a transfer coefficient matrix estimation unit, and 980 is a singular value decomposition calculation unit.

  Signals received by antenna elements 961 to 96N are switched by 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 singular value decomposition calculation unit 980 and then output to corresponding ports of the signal combining units 941 to 94N. 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 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.
The number of antenna elements of the spatial multiplexing transmission apparatus is M _T , the number of antenna elements of the spatial multiplexing transmission receiver (simply called “reception apparatus”) as the communication partner is M _R, and M _X is M _R and M _{Let T be} the smaller number. The spatial multiplexing transmission apparatus estimates the transfer coefficient matrix H of the propagation environment in which transmission is performed. The transfer coefficient matrix H is estimated as follows, for example. A preamble signal S ₀ (M _R × M _R matrix) that is known by both the transmission device and the reception device is transmitted from the reception device side, and the received signal X ₀ (M _T × M _R ) in the spatial multiplexing transmission device is transmitted. It can be obtained as a transposed matrix of a matrix obtained by multiplying the inverse matrix S ₀ ⁻¹ (M _R × M _R matrix) of the preamble signal.

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

Here, H _ij represents a transfer coefficient from the j-th antenna of the transmission apparatus to the i-th antenna of the reception apparatus, and V _ij is a transmission weight applied to the i-th antenna element for the j-th transmission beam in the transmission apparatus. U _ij is a complex conjugate of the reception weight applied to the reception signal of the i-th antenna with respect to the j-th transmission beam of the receiving apparatus. Here, the eigenvalue λ represents the transmission capacity of each path. The superscript H represents a complex conjugate 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. W and W ′ are shown in the following equation.

In the case of L = M _X , the reception signal X (MR × 1 vector) can be expressed as follows by transmitting the transmission signal S (M _X × 1 vector) using the transmission weight V in the transmission apparatus.

  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 a thermal noise N by the eigenvalue λ. The ratio (S / N ratio) with respect to is increased, 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 invention is to provide a transmission method and a transmission apparatus for spatial multiplexing transmission that can determine a transmission weight with a small amount of calculation.

The present invention has been made to solve the above problems, and the spatial multiplexing transmission method of the present invention includes a plurality of antenna elements, and determines a transmission weight suitable for the propagation environment from the estimated transmission coefficient matrix. In this method, transmission weighting is performed on a transmission signal and transmission is performed using space division multiplexing, and an orthogonalization method is applied to a column vector of a correlation matrix obtained from an estimated transfer coefficient matrix as the transmission weight. Alternatively, the orthogonalization method is applied to the column vector of the inverse matrix of the correlation matrix obtained from the estimated transfer coefficient matrix.
This makes it possible to determine the transmission weight without performing singular value decomposition calculation with a large calculation load, and can significantly reduce the calculation amount.

In the spatial multiplexing transmission method of the present invention, when the transmission weight is a correlation matrix obtained from an estimated transfer coefficient matrix or an inverse matrix of a correlation matrix using an orthogonalization method, An orthogonal vector obtained by applying an orthogonalization method with a large norm is used.
This makes it possible to determine the transmission weight without performing singular value decomposition calculation with a large calculation load, and can significantly reduce the calculation amount.

The spatial multiplexing transmission method of the present invention includes a plurality of antenna elements, determines a transmission weight suitable for the propagation environment from the estimated transmission coefficient matrix, performs transmission weighting on the transmission signal, and then performs space division multiplexing. In the transmission method for spatial multiplexing transmission, a transmission weight obtained by standardizing a column vector of an inverse matrix of an estimated transfer coefficient matrix to a certain value is used as a transmission weight. As a weight, an orthogonal vector obtained by applying an orthogonalization method to a column vector of an inverse matrix of the estimated transfer coefficient matrix is used.
This makes it possible to determine the transmission weight without performing singular value decomposition calculation with a large calculation load, and can significantly reduce the calculation amount.

In addition, the spatial multiplexing transmission apparatus of the present invention is a spatial multiplexing transmission apparatus that uses N (N ≧ 2) antenna elements and performs transmission by L (N ≧ L ≧ 2) spatial multiplexing. A switching unit that is connected to each of the antenna elements and switches between a received signal and a transmission signal, and a transfer coefficient matrix that is connected to the switching unit and that receives a signal output from the switching unit at the time of reception as an input signal and estimates a transfer coefficient matrix Calculate the column vector of the correlation matrix, which is the product of the complex conjugate transpose matrix of the transfer coefficient matrix estimated by the transfer coefficient matrix estimation unit and the transfer coefficient matrix, or the column vector of the inverse matrix of the correlation matrix. A transmission weight determination unit that calculates and outputs the corresponding column vector as a transmission weight to the multi-beam forming unit, and performs serial-parallel conversion on the input signal to be transmitted, and assigns it to the spatial multiplexing number L. Dividing the serial-parallel conversion unit, the output signal of the serial-parallel conversion unit as an input signal, a transmission unit that outputs a transmission signal system to a multi-beam forming unit, and a signal input from the transmission unit as an input signal, A multi-beam forming unit that divides the signal into N signals, performs weighting determined by the transmission weight determining unit, and then outputs to a corresponding port of the N signal combining units; superimposing the output from the corresponding L-number of the multi-beam forming portion into L port signals, e Bei and a signal synthesizing unit for outputting to the other port of the switching unit, the transmit weight determination unit, The transmission weight is obtained from the transmission coefficient matrix estimated by applying the orthogonalization method to the column vector of the correlation matrix obtained from the transmission coefficient matrix estimated by the transmission coefficient matrix estimation unit. Column vector of the inverse matrix of the correlation matrix using the orthogonal vectors obtained by applying the orthogonalization method to that, and outputs the multi-beam forming unit.
This makes it possible to determine the transmission weight without performing singular value decomposition calculation with a large calculation load, and can significantly reduce the calculation amount.

In the spatial multiplexing transmission apparatus according to the present invention, the transmission weight determining unit may use, as the transmission weight, a correlation matrix obtained from the transfer coefficient matrix estimated by the transfer coefficient matrix estimation unit, or an inverse matrix of the correlation matrix. On the other hand, in the case of using the orthogonalization method, the orthogonal vector obtained by applying the orthogonalization method from the one having a large norm is output to the multi-beam forming unit.
This makes it possible to determine the transmission weight without performing singular value decomposition calculation with a large calculation load, and can significantly reduce the calculation amount.

In addition, the spatial multiplexing transmission apparatus of the present invention uses N (N ≧ 2) antenna elements and performs transmission by L (N ≧ L ≧ 2) spatial multiplexing. A switching unit that is connected to each of the antenna elements and switches between a received signal and a transmission signal, and a transfer coefficient matrix that is connected to the switching unit and that receives a signal output from the switching unit at the time of reception as an input signal and estimates a transfer coefficient matrix An estimation unit, an inverse matrix of the transmission coefficient matrix estimated by the transmission coefficient matrix estimation unit, a transmission weight determination unit that outputs a corresponding column vector as a transmission weight to the multi-beam forming unit, and an input signal to be transmitted Serial-parallel conversion is performed, and the serial-parallel conversion unit that distributes to the spatial multiplexing number L, and the output signal of the serial-parallel conversion unit is used as an input signal. A transmitter that outputs to a multi-beam forming unit, and a signal input from the transmitter as an input signal is divided into N signals, weighted as determined by the transmission weight determiner, and then N signals A multi-beam forming unit that outputs to a corresponding port of the combining unit, and a signal output from the corresponding L multi-beam forming units to L ports among the multi-beam forming units is superimposed, and the switching unit And a signal synthesizer that outputs to the other port of the transmission multiplex transmission apparatus, wherein the transmission weight determination unit uses the transmission coefficient estimated by the transmission coefficient matrix estimation unit as the transmission weight. The present invention is characterized in that an orthogonal vector obtained by applying an orthogonalization method to a column vector of an inverse matrix is output to a multi-beam forming unit.
This makes it possible to determine the transmission weight without performing singular value decomposition calculation with a large calculation load, and can significantly reduce the calculation amount.

  The spatial multiplexing transmission method of the present invention includes a plurality of antenna elements, determines a transmission weight suitable for the propagation environment from the estimated transmission coefficient matrix, performs transmission weighting on the transmission signal, and performs space division multiplexing. A transmission weight using a transmission weight obtained by normalizing a column vector of a correlation matrix, which is a product of a complex conjugate transposed matrix of a transfer coefficient matrix and a transfer coefficient matrix, to a certain value, or Since the column vector of the inverse matrix of the correlation matrix obtained from the estimated transfer coefficient matrix is standardized to a certain value, the transmission weight is determined without performing the singular value decomposition operation with a large calculation load. And the amount of calculation can be significantly reduced.

  The spatial multiplexing transmission method of the present invention includes a plurality of antenna elements, determines a transmission weight suitable for the propagation environment from the estimated transmission coefficient matrix, performs transmission weighting on the transmission signal, and then performs space division. A transmission method using multiplexing, wherein as the transmission weight, an orthogonalization method is applied to a column vector of a correlation matrix obtained from an estimated transfer coefficient matrix, or a correlation matrix obtained from an estimated transfer coefficient matrix Since the orthogonalization method is applied to the column vector of the inverse matrix, it is possible to determine the transmission weight without performing the singular value decomposition calculation with a large calculation load, and the calculation amount can be significantly reduced.

  Further, in the spatial multiplexing transmission method of the present invention, when the transmission weight uses a correlation matrix obtained from the estimated transfer coefficient matrix or an inverse matrix of the correlation matrix using an orthogonalization method Uses the orthogonal vector obtained by applying the orthogonalization method from the one with the large norm, so that it is possible to determine the transmission weight without performing the calculation of the singular value decomposition with a large calculation load. The amount can be significantly reduced.

  The spatial multiplexing transmission method of the present invention includes a plurality of antenna elements, determines a transmission weight suitable for the propagation environment from the estimated transmission coefficient matrix, performs transmission weighting on the transmission signal, and then performs space division. A method of transmitting using multiplexing, wherein a transmission weight is obtained by normalizing a column vector of an inverse matrix of an estimated transfer coefficient matrix to a certain value, Since the orthogonal vector obtained by applying the orthogonalization method to the column vector of the inverse matrix of the estimated transfer coefficient matrix is used as the transmission weight, transmission is performed without performing computation of singular value decomposition with a large computation load. The weight can be determined, and the amount of calculation can be significantly reduced.

  In the spatial multiplexing transmission apparatus according to the present invention, N (N ≧ 2) antenna elements are used, and the spatial multiplexing transmission apparatus performs transmission by L (N ≧ L ≧ 2) spatial multiplexing. A switching unit that is connected to each of the antenna elements and switches a reception signal and a transmission signal; and a transfer coefficient that is connected to the switching unit and that receives a signal output from the switching unit at the time of reception as an input signal and estimates a transfer coefficient matrix A matrix estimation unit and a column vector of a correlation matrix that is a product of a complex conjugate transposed matrix of the transmission coefficient matrix estimated by the transmission coefficient matrix estimation unit and the transmission coefficient matrix, or a column vector of an inverse matrix of the correlation matrix A transmission weight determination unit that outputs the corresponding column vector as a transmission weight to the multi-beam forming unit, and performs serial-parallel conversion on the input signal to be transmitted, and performs spatial multiplexing A serial-parallel conversion unit that distributes data to L, a transmission unit that outputs an output signal of the serial-parallel conversion unit as an input signal, and outputs a transmission signal system to the multi-beam forming unit, and a signal input from the transmission unit as an input signal A multi-beam forming unit that divides the signal into N signals, performs weighting determined by the transmission weight determining unit, and then outputs the signals to corresponding ports of the N signal combining units; and the multi-beam forming unit A signal combining unit that superimposes the signals output from the corresponding L multi-beam forming units to the L ports and outputs the signals to the other port of the switching unit. Therefore, it is possible to determine the transmission weight without performing the calculation of the singular value decomposition having a large value, and the calculation amount can be significantly reduced.

  Further, in the spatial multiplexing transmission apparatus according to the present invention, the transmission weight determining unit orthogonalizes the transmission weight with respect to a column vector of a correlation matrix obtained from the transmission coefficient matrix estimated by the transmission coefficient matrix estimation unit. Since the orthogonal vector obtained by applying the orthogonalization method to the column vector of the inverse matrix of the correlation matrix obtained from the transfer coefficient matrix estimated by applying the method is output to the multi-beam forming unit, This makes it possible to determine the transmission weight without performing the singular value decomposition calculation with a large calculation load, and can significantly reduce the calculation amount.

  In the spatial multiplexing transmission apparatus according to the present invention, the transmission weight determination unit may use, as the transmission weight, a correlation matrix obtained from the transfer coefficient matrix estimated by the transfer coefficient matrix estimation unit, or an inverse of the correlation matrix. When using the orthogonalization method for the matrix, the orthogonal vector obtained by applying the orthogonalization method from the one with the large norm is used to output to the multi-beam forming unit. It is possible to determine the transmission weight without performing a calculation of a singular value decomposition with a large load, and the calculation amount can be significantly reduced.

  In the spatial multiplexing transmission apparatus of the present invention, N (N ≧ 2) antenna elements are used, and L (N ≧ L ≧ 2) spatial multiplexing transmission is performed in the spatial multiplexing transmission apparatus. A switching unit that is connected to each of the antenna elements and switches a reception signal and a transmission signal; and a transfer coefficient that is connected to the switching unit and that receives a signal output from the switching unit at the time of reception as an input signal and estimates a transfer coefficient matrix A matrix estimation unit, a transmission weight determination unit that calculates an inverse matrix of the transmission coefficient matrix estimated in the transmission coefficient matrix estimation unit, and outputs a corresponding column vector as a transmission weight to the multi-beam forming unit, and an input signal to be transmitted The serial-parallel conversion is performed, and the serial-parallel conversion unit that distributes to the spatial multiplexing number L, and the output signal of the serial-parallel conversion unit is used as an input signal, and is transmitted. After transmitting the signal system to the multi-beam forming unit and the signal input from the transmission unit as an input signal, the signal is divided into N signals, and weighting determined by the transmission weight determination unit is performed. A multi-beam forming unit that outputs to a corresponding port of N signal combining units, and a signal output to L ports from the corresponding L multi-beam forming units among the multi-beam forming units is superimposed And a signal synthesizer that outputs to the other port of the switching unit, wherein the transmission weight determination unit uses the transmission coefficient matrix estimation unit as the transmission weight. Since the orthogonal vector obtained by applying the orthogonalization method to the column vector of the inverse matrix of the estimated transfer coefficient matrix is output to the multi-beam forming unit, the computation load It makes it possible to determine the transmission weight without calculation of a large singular value decomposition, amount of calculation can be significantly reduced.

It is a block diagram which shows the 1st structural example of the transmitter for spatial multiplexing transmission of this invention. It is a block diagram which shows the 2nd structural example of the transmitter for spatial multiplexing transmission of this invention. 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.

  Next, the best mode for carrying out the present invention will be described with reference to the drawings.

[First Embodiment]
Hereinafter, a first embodiment of the present invention will be described in detail with reference to FIG. FIG. 1 is a block diagram showing a first configuration example of a spatial multiplexing transmission apparatus according to the present invention. When performing communication for obtaining high transmission quality by transmission directivity control that is optimal for a propagation environment, transmission weights are set. It shows a configuration that makes it possible to determine more easily.

  Reference numeral 110 is a serial-parallel conversion unit, 121 to 12L are transmission units, 131 to 13L are multi-beam forming units, 141 to 14N are signal synthesis units, 151 to 15N are switching units, 161 to 16N are antenna elements, and 170 is a transmission A coefficient matrix estimation unit 180 is a transmission weight determination unit.

  Signals received by the antenna elements 161 to 16N are switched by the 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 transmission weight determination unit 180. The transmission weight determining unit 180 determines the transmission weight as described below, and outputs the transmission weight to the multi-beam forming units 131 to 13L.

  The transmission signal series 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 obtained by multiplying the transmission weight determined by the transmission weight determining unit 180 by an analog amount or a digital amount, and then corresponding ports of the signal combining 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 switching units 151 to 15N.

  For simplicity, let us consider communication when the number of antenna elements of the receiving device and the number of antenna elements of the transmitting device is M and the number of space division multiplexing is L.

The spatial multiplexing transmission device receives the preamble signal S ₀ (M × M matrix) transmitted from the reception device, and the transmission coefficient matrix estimation unit 170 converts the received signal X ₀ (M × M) into an inverse matrix of the preamble signal. The transfer coefficient matrix H is estimated by multiplying S ₀ ⁻¹ (M × M matrix) and obtaining a transposed matrix.

  The transmission weight determination unit 180 obtains a complex conjugate transpose matrix of the transfer coefficient matrix as the transmission weight, and as the transmission weight W,

Is output to the multi-beam forming unit. Here, [] _L is an operator that selects L column vectors from the matrix, and P is

P _{1 to} p _L are the norm values of the corresponding column vectors of VDU ^H , and α _{1 to} α _L represent the power values distributed to each beam. Hereinafter, for the sake of simplicity, let α _{1 to} α _L be 1, and consider the case where L = M.

  When the multi-beam forming units 131 to 13L transmit the transmission signal S (L × 1 vector) using such transmission weight W, the signal X (M × 1 vector) received by the receiving apparatus is It can be expressed as follows.

Here, UD ² U ^HP is

  Since the value of the diagonal component increases, the effect of a decoding algorithm such as ZF (Zero Forcing) or MMSE (Minimum Mean Square Error) can be enhanced in the receiving apparatus. Further, when L vectors are selected from the complex conjugate transpose matrix of the transfer coefficient matrix, the transmission capacity can be increased by selecting the vector vector having a large norm.

Interference between signals can be further reduced by using the orthogonalization method for the column vector selected here. The column vectors selected here are denoted by v ₁ , v ₂ ,..., V _{L, and the} bonds in vectors a and b are represented by (a, b). When Gram Schmidt's orthogonalization method is performed with v ′ ₁ = v ₁ ,

As described above, the orthogonal vectors v ′ ₁ , v ′ ₂ ..., V ′ _L can be newly obtained. At this time, the transmission capacity can be further increased by using the orthogonalization method in order from the column vector having the largest norm.

  In addition, the transmission weight determining unit 180 obtains an inverse matrix of the transmission coefficient matrix as the transmission weight, and as the transmission weight W,

  Are output to the multi-beam forming units 131 to 13L. Where P is

Can be represented _as, p 1 ~p _L is the norm of the value of the corresponding column vector _{^{VD -1 U H, α 1 ~α}} L represents a power value to be distributed to each beam. Hereinafter, for the sake of simplicity, let α _{1 to} α _L be 1, and consider the case where L = M.

  When the multi-beam forming units 131 to 13L transmit the transmission signal S (L × 1 vector) using such transmission weights W, the signal X (M × 1 vector) received by the receiving apparatus is as follows. It can be expressed as follows.

  And the decoding load on the receiving side is reduced. Further, when L vectors are selected from the complex conjugate transpose matrix of the transfer coefficient matrix, the transmission capacity can be increased by selecting one having a small norm of the column vector.

Interference between signals can be further reduced by using the orthogonalization method for the column vector selected here. The vectors selected here are denoted by v ₁ , v ₂ ,..., V _L , and the internal bonds of vectors a and b are represented by (a, b). When Gram Schmidt's orthogonalization method is performed with v ′ ₁ = v ₁ ,

As described above, the orthogonal vectors v ′ ₁ , v ′ ₂ ..., V ′ _L can be newly obtained. At this time, the transmission capacity can be further increased by using the orthogonalization method in order from the column vector having the largest norm. However, in this case, v ′ _{1 has a} high correlation with the transmission weight having the smallest eigenvalue, and thus it is necessary to rearrange the transmission weight vectors in the reverse order.

Here, the number of transmission elements N, the receiving element number M, when performing the L spatial multiplexing as N> M, a transmission weight W ^H obtained from the complex conjugate transposed matrix of the transfer coefficient matrix, the transmission obtained from the inverse matrix the weight _{W I} are shown below.

Considering the above equation and the relationship that the eigenvalue is λ ₁ > λ ₂ ...> Λ _M , each column vector of equation (14) is the ideal transmission weight represented by equation (2). It can be seen that the correlation is high with the column vector (v ₁₁ , v ₂₁ ,..., V _N1 ) corresponding to one eigenvalue. On the other hand, the equation (15) is highly correlated with the column vector (v _1M , v _2M ,..., V _NM ) corresponding to the smallest eigenvalue. This select any column vector from W _H and W _I from, it is possible to further improve transmission quality by using the orthogonalization method.

Further, when the correlation matrix H ^H H of the estimated transfer coefficient matrix H and its inverse matrix are expressed using U, V, and D,

It becomes. Here, considering that the eigenvalues have a relationship of λ ₁ > λ ₂ >...> Λ _M , each column vector of the equation (16) is the first ideal transmission weight expressed by the equation (2). It can be seen that the correlation with the column vectors (v ₁₁ , v ₂₁ ,..., V _N1 ) corresponding to the eigenvalues becomes high. On the contrary, the equation (17) is highly correlated with the column vector (v _1M , v _2M ,..., V _NM ) corresponding to the smallest eigenvalue. From this, it is expected that transmission quality can be further improved by selecting an arbitrary column vector of the correlation matrix and its inverse matrix and using it in combination with the orthogonalization method of transmission weights shown so far.

  Further, the present invention uses a transmission weight W ″ that has a correlation with the transmission weight obtained from the singular value decomposition expressed by the equation (1) when estimating the transfer coefficient matrix with the communication counterpart station. The use of the preamble signal is more effective, and the estimated transfer coefficient matrix H ′ is

  Since the transmission weight of the communication partner station has a correlation with U, α> β. At this time, the equations (14) and (15) are

  If α >> β, it can be seen that the ideal transmission weight can be expressed by equation (2).

    Further, all or a part of the calculation from the estimation of the transfer coefficient matrix to the determination of the transmission weight can be performed in the communication partner station, and the directivity control can be similarly performed using the feedback information.

[Second Embodiment]
Next, a second embodiment of the present invention will be described with reference to FIG. FIG. 2 shows a second embodiment of the transmission device for spatial multiplexing transmission according to the present invention, in which transmission weights are more easily determined when performing communication for obtaining high transmission quality by transmission directivity control that is optimal for the propagation environment. The configuration that enables this is shown.

  In FIG. 2, reference numeral 110 is a serial-parallel converter, 121 to 12L are transmitters, 131 to 13L are multi-beam forming units, 141 to 14N are signal synthesizers, 151 to 15N are switching units, and 161 to 16N are antenna elements. , 170 is a transfer coefficient matrix estimation unit, 210 is a reception weight calculation unit, 220 is a transmission weight candidate storage unit, and 230 is an orthogonalization calculation unit.

  Signals received by the antenna elements 161 to 16N are switched by the switching units 151 to 15N and output to the transfer coefficient matrix estimation unit 170. The transfer coefficient matrix estimation unit 170 calculates a transfer coefficient matrix from the received preamble signal and outputs it to the reception weight calculation unit 210. The reception weight calculation unit 210 calculates reception weights for decoding, and outputs reception weight candidates generated in the process to the transmission weight candidate storage unit 220. The transmission weight candidate storage unit 220 outputs transmission weight candidates to the orthogonalization calculation unit 230, and the orthogonalized transmission weights are output to the multi-beam forming units 131 to 13L as transmission weights.

  The transmission signal sequence is distributed to the spatial division multiplexing number L by serial-parallel conversion 110, modulated by transmission units 121 to 12L, and output to multi-beam forming units 131 to 13L. Each signal sequence input to the multi-beam forming units 131 to 13L is subjected to the transmission weight determined by the transmission weight candidate storage unit 220, and then output to the corresponding ports of the signal combining units 141 to 14N. 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 switching units 151 to 15N.

  The reception weight calculation unit 210 outputs an arbitrary vector included in the complex matrix generated in the process of calculating the reception weight to the transmission weight calculation candidate storage unit 220 as a transmission weight candidate. For example, when the inverse matrix of the transfer coefficient matrix is used as the reception weight, the reception weight W ′ can be calculated as follows (when the number of elements on the reception side is large).

In this case, the complex conjugate transpose matrix H ^H , the inverse matrix (H ^H H) ⁻¹ H ^H , the correlation matrix H ^H H, and the inverse matrix of the transfer coefficient matrix are calculated in the middle of the calculation, and any of these is arbitrary. Is output to the transmission weight candidate storage unit, the transmission weight having a high correlation with the ideal transmission weight represented by the equation (2) can be formed by the orthogonalization calculation unit as described above.

[Explanation of effect by specific example]
Next, assuming that the number of transmitting elements is 4 and the number of receiving elements is 4, the column weight of the complex conjugate transpose matrix of the transfer coefficient matrix is obtained by performing the orthogonalization operation from the one with a large norm as the transmission weight The transmission capacity is compared with the conventional method in which transmission is performed in a non-directional manner without applying the transmission weight and the ideal value to which the ideal transmission weight given by Equation (2) 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, clusters with a Laplacian distribution and an angle spread of 25 ° around each of the transmitting station and the receiving station are No. 1 to No. 1. 6 to 6 were installed. The incoming waves are 90 waves, and 15 waves are received from No. 1 to No. 1 Divided into groups of up to 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. Was used to calculate the cumulative probability of the transmission capacity. The result is shown in FIG. According to FIG. 5, in the 50% value of the cumulative probability, the value is 8.6% lower than the ideal value, but an increase of 37.7% is obtained compared to the conventional method that does not use directivity control. showed that.

  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 transmission weights with a simple calculation and realize communication with a high transmission rate. This is useful for a transmission method and a transmission device for transmission.

110 Serial-parallel converters 121 to 12L Transmitters 131 to 13L Multi-beam forming units 141 to 14N Signal combiners 151 to 15N Switching units 161 to 16N Antenna element 170 Transfer coefficient matrix estimation unit 180 Transmission weight determination unit 210 Reception weight calculation unit 220 Transmission weight candidate storage unit 230 Orthogonalization operation unit

Claims (6)

A method comprising a plurality of antenna elements, determining a transmission weight suitable for a propagation environment from an estimated transmission coefficient matrix, performing transmission weighting on a transmission signal, and transmitting using space division multiplexing,
As the transmission weight, an orthogonalization method is applied to the column vector of the correlation matrix obtained from the estimated transfer coefficient matrix, or
A transmission method for spatial multiplexing transmission, wherein an orthogonalization method is applied to a column vector of an inverse matrix of a correlation matrix obtained from an estimated transfer coefficient matrix. As the transmission weight,
When using the correlation matrix obtained from the estimated transfer coefficient matrix or the inverse matrix of the correlation matrix using the orthogonalization method, the orthogonal vector obtained by applying the orthogonalization method from the one with the large norm The transmission method for spatial multiplexing transmission according to claim 1 , wherein: A method comprising a plurality of antenna elements, determining a transmission weight suitable for a propagation environment from an estimated transmission coefficient matrix, performing transmission weighting on a transmission signal, and transmitting using space division multiplexing,
In the transmission method for spatial multiplexing transmission, the transmission weight is obtained by standardizing a column vector of an inverse matrix of the estimated transfer coefficient matrix to a certain value.
An orthogonal vector obtained by applying an orthogonalization method to a column vector of an inverse matrix of an estimated transfer coefficient matrix is used as the transmission weight. In a spatial multiplexing transmission apparatus that performs transmission by L (N ≧ L ≧ 2) spatial multiplexing using N (N ≧ 2) antenna elements,
A 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 switching unit and receives a signal output from the switching unit at the time of reception as an input signal, and estimates a transfer coefficient matrix;
Calculate the column vector of the correlation matrix that is the product of the complex conjugate transpose matrix of the transfer coefficient matrix estimated by the transfer coefficient matrix estimation unit and the transfer coefficient matrix, or calculate the column vector of the inverse matrix of the correlation matrix, and A transmission weight determining unit that outputs a column vector to be transmitted to the multi-beam forming unit as a transmission weight;
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 system 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;
Wherein one of the multi-beam forming unit, superposing the output from the corresponding L-number of the multi-beam forming portion into L port signals, Bei give a signal combining unit for outputting to the other port of the switching unit,
The transmission weight determination unit
As the transmission weight, the column vector of the inverse matrix of the correlation matrix obtained from the transmission coefficient matrix estimated by applying the orthogonalization method to the column vector of the correlation matrix obtained from the transmission coefficient matrix estimated by the transmission coefficient matrix estimation unit Output to the multi-beam forming unit using the orthogonal vector obtained by applying the orthogonalization method to
A transmitter for spatial multiplexing transmission. The transmission weight determination unit
As the transmission weight, when using a correlation matrix obtained from the transfer coefficient matrix estimated by the transfer coefficient matrix estimator or an inverse matrix of the correlation matrix, the one having a large norm is used. 5. The transmitter for spatial multiplexing transmission according to claim 4 , wherein an orthogonal vector obtained by applying the orthogonalization method is used to output to the multi-beam forming unit. In a spatial multiplexing transmission apparatus that performs transmission by L (N ≧ L ≧ 2) spatial multiplexing using N (N ≧ 2) antenna elements,
A 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 switching unit and receives a signal output from the switching unit at the time of reception as an input signal, and estimates a transfer coefficient matrix;
A transmission weight determination unit that calculates an inverse matrix of the transmission coefficient matrix estimated in the transmission coefficient matrix estimation unit and outputs a corresponding column vector to the multi-beam forming unit as a transmission weight;
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 system 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;
A signal combining unit that superimposes the signals output from the corresponding L multi-beam forming units to the L ports among the multi-beam forming units and outputs the signals to the other port of the switching unit. In the spatial multiplexing transmission device characterized by
The transmission weight determination unit
An orthogonal vector obtained by applying an orthogonalization method to a column vector of an inverse matrix of the transmission coefficient matrix estimated by the transmission coefficient matrix estimation unit is used as the transmission weight, and is output to the multi-beam forming unit. A transmitter for spatial multiplexing transmission.

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