JPH11289213A - Adaptive receiver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately form null in the arrival direction of an unnecessary wave against an incoming wave having large correlation. SOLUTION: A correlation matrix estimation device 91 generates n receiving signal vectors Xn(k) for each of the frequency bands of plural (k×n) sub-carriers outputted from plural (k) branching filters 31, 32, calculates n matrices Rn(k, k) consisting of k×k elements by calculating the product of n vectors Xn(k) and their conjugate inverted vectors and a correlation matrix R(k, k) is calculated by averaging n matrices Rn(k, k). Then a vector Cn(k) is generated by calculating the product of a receiving signal, vector Xn(k) and a reference signal vector Dn(k) for each frequency and a correlation vector C(k) is calculated by averaging n vectors Cn(k). A weight coefficient is determined based on the product of the correlation matrix R(k, k) and a reverse matrix R<-1> (k, k). Since the correlation matrix is averaged about frequency, even an incoming wave having high correlation can easily be extracted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an adaptive receiver used for improving communication quality of a multi-carrier transmission system for transmitting data using a plurality of carriers having different frequencies.

[0002]

2. Description of the Related Art In a radio wave environment in which a desired wave and an unnecessary wave simultaneously arrive, an adaptive array antenna is known as a technique for controlling the directivity of an array antenna in accordance with the radio wave environment. FIG. 4 shows a basic configuration of an adaptive array antenna using two antenna elements A1 and A2 as an example of the related art. The signals x ₁ and x ₂ received by the two antenna elements A ₁ and A ₂ are respectively added to the weighting device 2
The weights are weighted by 1 and are synthesized by the synthesizer 22. The weighting factors w1 and w2 are determined by the control device 4 on the basis of the signals x ₁ and x ₂ received by the antenna elements A1 and A2 and information that has been known in advance. The control device 4 includes a correlation matrix estimation device 41, a correlation vector estimation device 42, an inverse matrix operation device 43, and a matrix multiplication device 44.

Hereinafter, the operation of the control device 4 will be described in detail. First, the signals x ₁ and x ₂ received by the antenna elements A 1 and A 2, and the weight coefficients w ₁ and w ₂ for performing the weighting are expressed by vectors as follows.

[0004]

X = [x ₁ x ₂ ] ^T (1)

[Formula 2] W = [w ₁ w ₂ ] ^T (2)

[0005] The optimum weight coefficient W _opt of the conventional adaptive array antenna is expressed by the following equation.

[0006]

(Equation 3)

However,

(Equation 4) (Four)

R _xd = E [x ₁ (t) · d ^* (t) × ₂ (t) · d ^* (t)] ^T (5)

Where d (t) is the waveform of the reference signal.
*, T, and + represent complex conjugate, matrix transpose, and complex conjugate transpose, respectively, and E [•] represents an operation for obtaining an average value. R _xx and r _xd are called a correlation matrix and a correlation vector, respectively. E in equations (4) and (5)
[•] is originally an ensemble average (collective average).

However, since it is practically impossible to obtain an ensemble average, in a conventional adaptive array antenna, the ensemble average calculation is substituted by a time average.

Specifically, first, an instantaneous input matrix is calculated based on signals received by each antenna.

(Equation 6) Create Since R ＾ _xx changes every moment, in the related art, a time average of R ＾ _xx is obtained and used as an estimated value of the correlation matrix.

On the other hand, the correlation vector r _xd is similarly obtained by time averaging. That is, by taking the product of the signal received by each antenna and the reference signal, the instantaneous correlation vector,

Seeking Equation 7] r ^ _xd = ^{_{[x 1 (t) · d *}} (t) x 2 (t) · d * (t) ] ^T (7), estimation of the correlation vector by averaging this time Get the value r _xd .

Next, a weighting factor is determined based on equation (3). In other words, to obtain calculated by the inverse matrix calculation unit an inverse matrix R ^-1 _xx estimate R _xx of the correlation matrix, and this, by obtaining the product of the estimated value r _xd of the correlation vector, the weighting coefficient vector W. By using the respective elements w ₁ and w ₂ of W as weighting factors of the weighting device, a null is formed in the arrival direction of the unnecessary wave in the combined directivity of the array antenna, and as a result, only the desired wave is received. Is done.

[0013]

When an unnecessary wave is radiated from a different wave source from the desired wave, or when the arrival times of the respective waves are greatly different even when transmitted from the same wave source as the desired wave, As described above, an appropriate weighting factor can be obtained by performing time averaging instead of ensemble averaging. However, if the desired wave and the unnecessary wave are radiated from the same wave source and the arrival times of the two arriving waves are very close, an appropriate weighting factor cannot be obtained. This is because, when the arrival times of the incoming waves are very close, the estimated value of the correlation matrix obtained by the time average becomes a singular matrix, and there is no inverse matrix thereof.

As a method for avoiding this, a method has been considered in which a small amount is added to the diagonal components of the correlation matrix estimated by using the time average to forcibly regularize. However, even if the optimal weighting factor is determined using the corrected correlation matrix,
The null is not always formed in the arrival direction of the unnecessary wave, and the directivity may be such that both the desired wave and the unnecessary wave are received. In this case, the received desired wave and unnecessary wave are canceled in the combiner, so that the output signal may be extremely small.

Further, a method of performing a spatial average or a moving average instead of the time average has been devised. This utilizes the fact that the phase difference between incoming waves differs depending on the position of the receiving point. In the method of performing the spatial averaging or the moving average, the more the data is averaged on the spatial axis, the more accurately the correlation matrix can be estimated. But,
In the case of spatial averaging, if the number of times of averaging is increased, the degree of freedom for directivity control is reduced, and appropriate directivity cannot be formed. In the case of the moving average, since the arrival direction and intensity of the incoming wave change depending on the position of the receiving point, a null is not accurately formed in the arrival direction of the unnecessary wave.

An object of the present invention is to provide an adaptive receiving apparatus which can form a null accurately in the arrival direction of an unnecessary wave even when the correlation between the incoming waves is large.

[0017]

The first aspect of the present invention is an adaptive receiving apparatus used in a system for modulating a plurality of data, and transmitting the modulated signals using carriers of different frequencies. The adaptive receiving apparatus, an antenna that receives a signal and outputs a signal having a plurality of delay time differences, and a plurality of demultiplexers that demultiplex each signal output by the antenna for each of a plurality of carriers,
A plurality of weighting devices for weighting the output signals of the duplexers, a plurality of combiners for combining the output signals of the plurality of weighting devices for each carrier of the same frequency, and taking in and outputting the output signals of the plurality of duplexers And a control device for controlling the weight coefficient of the device. The control device includes a correlation matrix estimating device for estimating a correlation matrix of a received signal, and a weighting factor calculating device for calculating a weighting factor using the correlation matrix estimated by the correlation matrix estimating device.
Then, the correlation matrix estimating apparatus uses the plurality of (k × n) carriers output from the plurality (k) of the demultiplexers to obtain n received signals composed of k elements for each carrier frequency. Generate a vector Xn (k) and then a received signal vector X
By calculating the product of n (k) and its conjugate transpose vector, n matrices Rn (k, k) composed of k × k elements are calculated, and the n matrices Rn (k, k) are averaged. Then, the correlation matrix R (k, k) is calculated, and the weighting factor calculation device calculates the correlation matrix R (k, k) output from the correlation matrix estimation device.
The weighting factor is determined using k).

The value k is equal to or less than the number of a plurality of signals having a delay time difference output from the antenna, and the value n is equal to or less than the number of carriers.

According to a second aspect of the present invention, the weight coefficient calculating device uses a plurality of (k × n) carriers respectively output from a plurality of (k) demultiplexers to generate k k for each frequency of each carrier. Received signal vector Xn composed of n elements
(K) and n reference signal vectors Dn (k) composed of k elements using reference signals prepared in advance on the reception side, and then n received signal vectors By calculating the product of Xn (k) and n reference signal vectors Dn (k) for each frequency, n vectors Cn (k) composed of k elements are generated, and further n vectors A correlation vector C (k) is calculated by averaging Cn (k), and an inverse matrix R ⁻¹ (k, k) of the correlation matrix R (k, k) estimated by the correlation matrix estimating apparatus and the correlation vector C The weight coefficient is determined based on the product of (k).

Further, according to the invention of claim 3, the weight coefficient calculating device is provided for each frequency of each carrier by using a plurality of (k × n) carriers respectively output from a plurality of (k) demultiplexers. n received signal vectors Xn composed of k elements
(K) and n reference signal vectors Dn (k) composed of k elements using reference signals prepared in advance on the reception side, and then n received signal vectors By calculating the product of Xn (k) and n reference signal vectors Dn (k) for each frequency, n vectors Cn (k) composed of k elements are generated, and further n vectors A correlation vector C (k) is calculated by averaging Cn (k), and LMS, RLS are calculated using the obtained correlation vector C (k) and the correlation matrix R (k, k) estimated by the correlation matrix estimating device. , SMI are determined based on one of the algorithms.

According to a fourth aspect of the present invention, the weight coefficient calculating device generates a direction vector composed of k elements determined from the arrival direction of the radio wave and the arrangement of the antenna elements, and correlates the obtained direction vector with the obtained direction vector. The weighting factor is determined based on either DCMP or MSN algorithm using the correlation matrix R (k, k) estimated by the matrix estimation device.

Further, according to a fifth aspect of the present invention, a weighting factor calculating device is provided with a correlation matrix R estimated by a correlation matrix estimating device.
The weight coefficient is determined based on a power minimization algorithm using (k, k).

[0023]

The transmitting side transmits a plurality of carriers (hereinafter, referred to as carriers) in order to correctly estimate the correlation matrix even when the correlation between the arriving waves is large. The receiving side obtains an instantaneous input matrix for each carrier, and estimates a correlation matrix by averaging the obtained instantaneous input matrices of a plurality of carriers with respect to the carriers. That is, in the prior art, the correlation matrix is estimated by frequency averaging, while the correlation matrix is estimated by time averaging or spatial averaging.

Since the phase difference between each arriving wave arriving at the receiving point differs for each frequency, if the weighting factor is determined using the estimated value of the correlation matrix obtained by the frequency averaging, the arrival time of the arriving wave will be extremely large. Even when approaching, it is possible to reliably form a directivity having a null in the arrival direction of the unnecessary wave. Further, from the viewpoint of time, since an instantaneous correlation matrix is obtained, the correction coefficient is also an instantaneous value, and adjustment can be performed in real time even when the environment fluctuates over time. .

[0025]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a description will be given based on specific embodiments of the present invention. The present invention is not limited to the following embodiments. In the following embodiments, the number n of carriers is 3 and the number k of antenna elements is 2 for simplicity of description. (First Embodiment) FIG. 1 shows the configuration of a first specific example. The first specific example is a configuration example when a multi-carrier signal including three carriers is received using a two-element antenna. The array antenna 1 has two antenna elements A1 and A2.
The signals g1 and g2 received by the respective antenna elements A1 and A2 are split by the splitters 31 and 32 for each carrier. The split signals (x ₁₁ , x ₁₂ ,
x ₁₃ ) and (x ₂₁ , x ₂₂ , x ₂₃ ) are weighted by weighting devices 51 and 52, respectively. Weighted signals are combined by the combiner 60 for each carrier, the signal is synthesized x _1, x _2, x _3, respectively, it is demodulated by the demodulator 70. The demodulated data sequence L _{1 for} each carrier,
L ₂ and L ₃ are returned to one data series by the parallel / serial converter 80. The signals (x ₁₁ , x ₁₂ , x ₁₃ ) and (x ₂₁ , x ₂₂ , x ₂₃ ) demultiplexed by the demultiplexers 31 and 32 are input to a control device 90 for determining a weight coefficient. The control device 90 determines weighting factors w ₁ and w ₂ for signals received by the antenna elements A 1 and A 2.

The control device 90 comprises a correlation matrix estimating device 91 for estimating a correlation matrix, and a weight coefficient calculating device 92. Among them, the weight coefficient calculating device 92 includes an inverse matrix calculating device 921 for obtaining an inverse matrix of the correlation matrix estimated by the correlation matrix estimating device 91, and signals (x ₁₁ , x ₁₂₎ split by the splitters 31 and 32. _{, x 13), (x 21} , x 22, x 23)
, And a correlation vector estimating device 922 for estimating a correlation vector, and a matrix multiplying device 923 for obtaining a product of an inverse matrix of the correlation matrix and the correlation vector and determining an optimal weight coefficient. It should be noted that the apparatus shown in FIG. 1 is all constituted by a numerical operation device for inputting a digital signal. Actually, the high-frequency wideband signal received by the array antenna 1 is frequency-converted into a baseband signal (a set of carriers modulated by a code string). This signal is sampled at predetermined time intervals and converted to a digital value. A waveform is given by a time sequence of the digital values. Therefore, the signals input to the control device 90, the signals input to the weighting devices 51 and 52, and the signals output from them have waveforms given by a time sequence of digital values.

The present invention is characterized by a method of determining the weighting coefficient by the control device 90. Hereinafter, the processing procedure of the first embodiment will be described in detail. Correlation matrix estimation device 9
1 includes signals x ₁₁ , x ₁₂ , and x _{13 for} each carrier received by the antenna element A 1 and demultiplexed by the demultiplexer 31, and signals for each carrier received by the antenna A 2 and demultiplexed by the demultiplexer 32. signal x _21, x _22, x ₂₃ of inputs. Note that [x ₁₁
x _21], [x ₁₂ x _22], [x ₁₃ x _23], respectively, the first carrier, second carrier, the received signal vector X1 regarding the third carrier (2), X2 (2) , X3
(2). This corresponds to the received signal vector Xn (k) in the claims.

The correlation matrix estimator 90, for each carrier, creating a momentary input matrix R _xx1, R _xx2, R _xx3 by the following equation.

(Equation 8)

(Equation 9)

(Equation 10)

[0029] These instantaneous input matrix R _xx1, R _xx2, R _xx3
Corresponds to n matrices Rn (k, k) composed of k × k elements described in the claims. The obtained instantaneous input matrix for each carrier is averaged based on the following equation to obtain an estimated value _Rxx of the correlation matrix.

[Number 11] _{R xx = (R xx1 + R} xx2 + R xx3) / 3 (11)

The estimated value R averaged by the number of carriers n
_xx corresponds to the correlation matrix R (k, k) described in the claims. Next, the operation of the weight coefficient calculation device 92 will be described. First, the signals (x ₁₁ , x ₁₂ , x ₁₃ ) of the respective carriers demultiplexed by the correlation vector estimation device 922,
Using (x ₂₁ , x ₂₂ , x ₂₃ ) and reference signals (d ₁₁ , d ₁₂ , d ₁₃ ) and (d ₂₁ , d ₂₂ , d ₂₃ ) for each carrier, the instantaneous correlation vector r for each carrier _xd1 , r _xd2 , r
_{Find xd3} . That is, the following calculation is performed.

[0031]

(12) r _xd1 = [x ₁₁ · d ₁₁ × ₂₁ · d ₂₁ ] ^T

[Number 13] (13) r _xd2 = _{[x 12 · d 12 x 22 ·} d 22 ] ^T

R _xd3 = [x ₁₃ · d ₁₃ × ₂₃ · d ₂₃ ] ^T (14)

[D ₁₁ d ₂₁ ], [d ₁₂ d ₂₂ ], [d ₁₃
d ₂₃ ] are a first carrier, a second carrier,
Reference signal vectors D1 (2), D1 for the third carrier
2 (2) and D3 (2). The column vectors r _xd1 , r _xd2 , and r _{xd3 of} three (n) elements 2 (k) correspond to the reference signal vector Dn (k) of the claims, and the vector Cn (k) of the claims. .

By averaging the obtained instantaneous correlation vectors on the frequency axis based on the following equation, an estimated value r _xd of the correlation vector is obtained.

R _xd = (r _xd1 + r _xd2 + r _xd3 ) / 3 (15)

The column vector r _xd having two (k) elements corresponds to the correlation vector C (k). Next, the estimated value of the correlation matrix (((1
1) Obtain the inverse matrix R ^-1 _xx of the expression). This inverse matrix R ^-1 _xx corresponds to the inverse matrix R ^-1 (k, k) in the claims.

Lastly, the matrix multiplier 923 calculates the product of the inverse matrix R ^-1 _xx of the correlation matrix and the estimated value r _xd of the correlation vector to obtain the weight coefficient vector W by the following equation.

[0036]

W = [w ₁ w ₂ ] ^T = R ⁻¹ _xx · r _xd (16)

The signal for each carrier is weighted using the respective elements w ₁ and w ₂ of the obtained weight coefficient vector W. In other words, each of the signals (x ₁₁ , x ₁₂ , x ₁₃ ) for each carrier output from the duplexer 31 is multiplied by the weighting factor w ₁ , and the signal for each carrier output from the duplexer 32 ( weighting coefficient w ₂ is applied to each of the _{x 21, x 22, x 23} ). The weighted signal for each carrier is combined by the combiner 60 for each carrier.

At this time, since the combined directivity of the array antenna 1 has a null formed in the arrival direction of the interference wave, only the component of the desired wave is output to the output of the combiner 60. The signals x ₁ , x ₂ , x ₃ output from the combiner 60 are
Is demodulated for each carrier to become encoded data.
This encoded data is parallel-to-serial converted by the parallel-to-serial converter 80 to become one column of high-speed encoded data.

As described above, according to the present invention, even when the arrival times of a plurality of incoming waves are approaching, only the desired incoming wave can be received. Therefore, the adaptive receiving apparatus according to the present invention is very useful as a technique for removing a multiplex wave which is a cause of deterioration of communication quality in mobile communication. In particular, in a multi-carrier transmission system in which high-speed communication is possible, since a plurality of carriers are used, high-speed, high-quality communication can be achieved by using the adaptive receiving apparatus of the present invention when receiving signals of the same system. Can be performed.

The system of the present invention is not limited to the multi-carrier transmission system, but may be applied to any wireless communication system that transmits signals of a plurality of frequencies from one transmitting station, such as a television broadcast or a cellular mobile phone. be able to.
In the above description, the case where the weight coefficient is determined using all the signals output from the duplexer is described. However, it is not always necessary to use all the signals, and the weight coefficient is determined using only some of the signals. The same effect can be obtained.
Although the reference signal uses a different value for each element, the same reference signal may be used for all elements. That is, d ₁₁ = d ₂₁ , d ₁₂ = d ₂₂ , and d ₁₃ = d ₂₃ .

(Second Embodiment) In the first embodiment, it is necessary to perform an inverse matrix operation when obtaining a weight coefficient. Since the number of elements in the matrix is proportional to the square of the number of antenna elements, as the number of antenna elements increases, the amount of calculation for finding the inverse matrix increases significantly. As a method of controlling the sequential weight coefficient by iterative calculation without performing an operation for obtaining an inverse matrix, LMS (Le
ast Mean Square) algorithm is known. The updating formula is shown in the following formula.

[0042]

W _{(m + 1)} = W _(m) + μ (r _xd −R _xx · W _(m) ) (17) where W _(m) represents a weight coefficient after updating m times, and μ is This is a constant called the step size. FIG. 2 shows an example of a configuration for controlling a weight coefficient based on an LMS algorithm as a second embodiment. The parts for demultiplexing, weighting, combining and demodulating the signal for each carrier are exactly the same as those in the first embodiment. The correlation matrix estimating device 91 and the correlation vector estimating device 922 of the control device 90 are the same as those of the first embodiment. Parts other than the correlation vector estimating device 922 in the weight coefficient calculating device 92 are configured to calculate the above equation (17).

In the new feature, the correlation matrix estimate R
_xx , the estimated value r _{xd of the} correlation vector and the weight coefficient W _(m) after the m-th iteration, and the ₍ m + 1) th weight coefficient W
_{(m + 1)} is calculated. Hereinafter, the procedure of updating the weight coefficient in the second embodiment will be described in detail.

(1) The product R _xx W _(m) of the estimated value R _xx of the correlation matrix obtained by the correlation matrix estimating device 91 and the weight coefficient W _(m) before updating outputted by the delay device 928 is The calculation is performed by the adder 924. (2) The adder / subtracter 925 uses the correlation vector estimator 92
R _xx from the estimated value r _xd of the correlation vector obtained by
W _(m) is _{subtracted, r xd -R xx W (m} ) is calculated. (3) The multiplier 926 multiplies r _xd −R _xx W _(m) by the step size μ, and updates the weighting coefficient μ (r _xd −R
_xx W _(m) ). (4) The weight coefficient W _(m) at the time of updating m times by the adder 927
Is added to the weighting factor, and the (m + 1) th weighting factor W
_{(m + 1)} is obtained. The signal for each carrier is weighted by the weight coefficient.

The procedure for one update of the weighting coefficient has been described above. In the next step, the obtained weighting coefficient W _{(m + 1)} is set as W _(m) by the delay device 928 in the same order from (1). Process is repeated. In the above description, the LMS algorithm has been described as an example of the most basic algorithm for controlling the sequential weight coefficient, but the SMI (Sample Matrix Inversio) is used.
n) algorithm and RLS (Recursive Least Squares)
) The weight coefficient may be controlled using an algorithm.

(Third Embodiment) In the adaptive receiving apparatuses of the first and second embodiments, a reference signal is used as information known in advance on the receiving side when determining a weighting factor. On the other hand, DCMP (Directionally Constrained) is used as an algorithm using information on the arrival direction of a desired wave.
Minimization of Power) algorithm and MSN (Max
An imum Signalto Noise ratio) algorithm is known. In the third embodiment, a weighting factor is determined based on these algorithms, and the configuration is shown in FIG.

The third embodiment differs from the first embodiment in that when determining the weighting factor, the estimated value r of the correlation vector is determined.
_The only difference is that the constraint vector C calculated by the constraint vector generator 929 is used instead of using _xd .
The constraint vector C in DCMP and MSN is represented by the following equation.

[0048]

C = [1 exp (j (2πD / λ) sinφ)] ^T (18) where D is the distance between the antenna elements, λ is the wavelength of the carrier of the center frequency, and φ is the arrival direction of the desired wave. , Respectively. Inverse matrix R ^-1 _{xx of} constraint vector C and estimated value of correlation matrix
If the product R ^-1 _xx C is used as a weighting factor, a null is formed in the arrival direction of the unnecessary wave while the gain of the combined directivity in the arrival direction of the desired wave remains constant. Therefore, only the desired wave is received.

If the constraint vector is C = [10] ^T (19), the third embodiment operates as a power inversion adaptive antenna. In this case, due to the combined directivity, a stronger arriving wave is more strongly suppressed. Therefore, when an unnecessary wave that is stronger than the desired wave is arriving, even if information such as the reference signal and the arrival direction of the desired wave is not obtained, the configuration of the third specific example can be adopted. Only can receive.

In all of the above embodiments, the number of carriers is three and the number of antenna elements is two for simplicity. However, the same holds when the number of carriers is n and the number of antenna elements is k (n and k are natural numbers). For the nth carrier, the instantaneous input matrix R _xxn
Is displayed in a matrix of k rows and k columns similar to (8), and (1
The estimated value R _xx of the correlation matrix represented by the expression 1) is a matrix of k rows and k columns, and each component is an average of the number n of carriers of each component of the instantaneous input matrix.

The instantaneous correlation vector r _xdn for the n-th carrier is a column vector of one row and k columns, and the estimated value r _xd of the correlation vector given by equation (15) is a column vector of one row and k columns. The component is the average of the number n of carriers of each component of the instantaneous correlation vector. The reference signal vector Dn (k) for the n-th carrier is a column vector of one row and k columns.
The weight coefficient vector in the equation (16) is a column vector of 1 row and k columns.

The numbers of k and n are arbitrary. However, as k increases, a large number of unnecessary waves can be removed, and as the number n increases, unnecessary waves can be removed with higher accuracy. Even in this generalized case, the weighting factor may be calculated using some of the n carriers. Of course, n can be 2 or more.

In the above embodiment, the sampling is performed at a period shorter than the minimum period of the baseband carrier, the baseband waveform is treated as digital value time series data, and all the calculations are performed by the computer system. That is, the transmitting side sets each carrier to P based on the encoded data.
A frequency-multiplexed baseband signal is obtained by inputting instantaneous values of n waveforms converted into signals such as SK and QPSK, and outputting a time-series value obtained by performing inverse FFT (fast inverse Fourier transform). Further, the carrier is modulated with this signal and transmitted. On the receiving side, the received signal is converted into a baseband signal, and this signal is sampled on a time axis and converted into a digital value. Then, a fixed time sequence of the digital values is subjected to FFT to obtain a baseband signal for each carrier. Thereafter, demodulation is performed for each carrier to obtain received encoded data. This method is called OFD
It is already well known as the M (orthogonal frequency multiplexing) system. The demodulation method of the multicarrier signal is not limited to the digital method of the above embodiment, but may be a method of processing an analog waveform by an analog circuit.

In the above embodiment, an array antenna in which a plurality of antenna elements are arranged is used. However, a device in which one antenna element, a delay circuit, and a branch circuit are connected in series is used, and the output of each branch circuit is used as an antenna. May be a signal having a plurality of delay time differences.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an adaptive communication device according to a first embodiment of the present invention.

FIG. 2 is a configuration diagram of an adaptive communication device according to a second embodiment of the present invention.

FIG. 3 is a configuration diagram of an adaptive communication device according to a third embodiment of the present invention.

FIG. 4 is a configuration diagram of a conventional adaptive communication device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Array antenna A1, A2 ... Antenna element 31, 32 ... Demultiplexer 51, 52 ... Weighting device 60 ... Synthesizer 70 ... Demodulator 80 ... Parallel-serial converter 90 ... Control device 91 ... Correlation matrix estimation device 92 ... Weight Coefficient calculation device 921 ... Inverse matrix operation device 922 ... Correlation vector estimation device 923 ... Matrix multiplication device

Claims (5)

[Claims] An adaptive receiving apparatus used in a system for modulating a plurality of data and transmitting the modulated signals using carriers of different frequencies, a signal receiving a signal and having a plurality of delay time differences. An antenna that outputs the signals, a plurality of demultiplexers that demultiplex each of the signals output by the antenna for each of a plurality of carriers, a plurality of weighting devices that respectively weight output signals of the demultiplexers, A plurality of combiners for combining the output signals of the weighting device for each carrier of the same frequency; and a control device for taking in the output signals of the plurality of duplexers and controlling a weight coefficient of the weighting device, wherein the control device is A correlation matrix estimating device for estimating a correlation matrix of a received signal, and a weighting factor using the correlation matrix estimated by the correlation matrix estimating device. Is composed of a weighting factor calculation unit for output, wherein the correlation matrix estimator, more plural output from (k-number) of the demultiplexer (k × n pieces)
To generate n received signal vectors Xn (k) consisting of k elements for each frequency of each carrier,
Next, by calculating the product of the received signal vector Xn (k) and its conjugate transpose vector, n matrices Rn (k, k) composed of k × k elements are calculated, and further n matrices Rn (k , K) to calculate a correlation matrix R (k, k), and the weighting factor calculation device determines a weighting factor using a correlation matrix output from the correlation matrix estimation device. Adaptive receiving device. 2. The weighting factor calculating apparatus according to claim 1, wherein the plurality of (k) demultiplexers are respectively output from a plurality of (k) duplexers.
× n) carriers for each carrier frequency
Generates n received signal vectors Xn (k) composed of n elements and n reference signal vectors Dn (k) composed of k elements using reference signals prepared in advance on the receiving side. , And then n received signal vectors Xn
By calculating the product of (k) and n reference signal vectors Dn (k) for each frequency, n vectors Cn (k) composed of k elements are generated, and further n vectors Cn By averaging (k), the correlation vector C (k)
Is calculated, and a weight coefficient is determined based on the product of the inverse matrix R ⁻¹ (k, k) of the correlation matrix R (k, k) estimated by the correlation matrix estimation device and the correlation vector C (k). The adaptive receiving apparatus according to claim 1, wherein: 3. The weighting factor calculation device according to claim 1, wherein the plurality of (k) demultiplexers are respectively output from a plurality of (k) duplexers.
× n) carriers for each carrier frequency
Generates n received signal vectors Xn (k) composed of n elements and n reference signal vectors Dn (k) composed of k elements using reference signals prepared in advance on the receiving side. , And then n received signal vectors Xn
By calculating the product of (k) and n reference signal vectors Dn (k) for each frequency, n vectors Cn (k) composed of k elements are generated, and further n vectors Cn By averaging (k), the correlation vector C (k)
Is calculated using the obtained correlation vector C (k) and the correlation matrix R (k, k) estimated by the correlation matrix estimation device.
The adaptive receiving apparatus according to claim 1, wherein the weighting factor is determined based on any one of MS, RLS, and SMI algorithms. 4. The weighting factor calculation device according to claim 1, wherein k is determined from the direction of arrival of the radio wave and the arrangement of the antenna elements.
Is generated, and the obtained direction vector and the correlation matrix R estimated by the correlation matrix estimating device are generated.
The adaptive receiving apparatus according to claim 1, wherein the weighting coefficient is determined based on either DCMP or MSN algorithm using (k, k). 5. The weighting factor calculation device, wherein the correlation matrix R (k,
The adaptive receiving apparatus according to claim 1, wherein the weighting coefficient is determined based on a power minimization algorithm using k).