JPH1168442A - Controller for array antenna - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a controller capable of handling a wide-band signal with simple configuration by setting the transfer functions H1(Z) or Hp(Z) of a first band pass filter means and the transfer functions G1(Z) or Gp(Z) of a second band pass filter means so that they are completely reproduced as receiving signal outputted by an A/D converting means. SOLUTION: Respectively plural P-number of band pass filters BPF:6-n-1 or BPF:6-n-p are provided with P-number of mutually different passing band, namely mutually different transmission functions H1(Z), Hp(Z). A complex number signal to be outputted from an adder is outputted to an adder 23 through an up sampler 21-p executing up-sampling processing by a prescribed rate D with respect to an inputted complex number signal and BPF:22-p with a transfer function Gp(Z). Then P-number of BPF:22-1 or BPF:22-p are provided with mutually different P-number of passing band namely provided with the transfer functions G1(Z) or Gp(Z).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a control device for an array antenna.

[0002]

2. Description of the Related Art In order to ensure good communication quality in mobile communication, a function of always capturing a desired wave is required.
It is necessary to have a function of removing frequency-selective fading generated in a multipath. For the latter, for example, the constant modulus algorithm (Consta
nt Modulus Algorithm: Hereinafter, referred to as a CM algorithm. ) Is known to be effective for removing unnecessary waves that are delayed waves having a correlation with a desired wave (for example,
Prior Art Document 1 "Takeo Ohgane et al.," Selective fading compensation characteristics of CMA adaptive array in land mobile communication ", IEICE Transactions, Vol. J73-B.
-II, No. 10, pp 489-497, 1990 1
October ". ).

Prior to the process using the CM algorithm, a known beam forming process and a known beam selecting process described below are executed. (A) Beam forming processing: a plurality of M received signals respectively received by each antenna element of the array antenna and a predetermined plurality of signals to be formed predetermined to be able to receive a desired wave within a predetermined radiation angle range. the direction of the main beam of the n beams, based on the reception frequency of the received signal, it calculates a plurality of n beam field strength E _n. (B) Beam selection processing: comparing the plurality of N beam electric field values calculated in the beam forming processing with a predetermined threshold value, selects and outputs only the beam electric field value equal to or greater than the threshold value I do.

In the CM algorithm, the main beam of the array antenna is directed to a desired direction of a desired wave and an unnecessary wave such as an interference wave is set based on a plurality of N or less beam electric field values selected by the beam selection processing. N weighting coefficients w _n (n = 1, 2, 2) for the received signal corresponding to each beam such that the receiving level in the arrival direction of
.., N) are calculated. In other words, this CM algorithm is unnecessary in a communication system using a signal wave of a desired wave whose envelope is known, by converting the waveform of the envelope changed by the influence of an unnecessary wave such as an interference wave into a desired shape. The reception level in the radiation pattern of the array antenna in the wave arrival direction is set to zero.

In a conventional array antenna using an adaptive algorithm such as the CM algorithm described above, the influence of a delayed wave can be removed by adaptively controlling the directivity. Not used. In order to solve this, a method of separating a direct wave and a delayed wave and performing diversity reception is described in, for example, prior art document 2 “Noboru Kuroiwa et al.,“ Configuration method of directional diversity reception using adaptive array antenna ””,
IEICE Transactions, B-II, Vol. J73-
B-II, No. 11, pp 755-763, November 1990 "(hereinafter referred to as a first conventional example).

In the first conventional example, a direct wave and a delayed wave are separated from a signal received in the following procedure and diversity reception is performed. (A) Extract a direct wave only using a conventional adaptive (adaptive) algorithm. (B) Next, the adaptive equalizer is operated using the extracted direct wave as a reference signal to extract only the delayed wave. (C) Finally, diversity reception is performed by multiplying the direct wave and the delayed wave extracted as described above by a weight coefficient so as to obtain the maximum signal-to-noise ratio.

[0007]

However, the first conventional example has the following problems. (A) Since the conventional adaptive algorithm is used, the adaptive equalizer is operated after a predetermined convergence condition is satisfied in the processing using the algorithm, so that the processing time is relatively long. (B) CM using adaptive algorithm, for example, CM
Since it is necessary to provide the A processing unit and a different processing unit called the adaptive equalizer, the hardware configuration becomes complicated. (C) It is impossible to process a so-called wideband signal in which a plurality of signals are multiplexed or spread spectrum modulated.

[0008] In addition, prior art document 3 “JMKhalab et a
l., “Novel multirate adaptive beamforming techniqu
e ", Electronics Letters, Vol.30, No.15, pp.1194-1195,1
994 "(hereinafter referred to as a second conventional example)
An adaptive beam forming apparatus is configured by using a multi-rate signal processing circuit having a plurality of N analysis filter banks and one synthesis filter bank, and can handle a wide band signal. It is necessary to obtain a reference signal in some form for beam forming (for example, transmitting from a transmission side or mixing a known signal into a transmission signal,
It is held on the receiving side and used as a reference signal. In any case,
Need to synchronize. ), There is a problem that the hardware configuration becomes complicated.

Further, prior art document 4 "Osamu Shibata et al.,
"Construction method of optical spatial signal processing multi-beam receiving antenna", IEICE technical report, MW96-47, O
PE 96-27, pp. 45-50, June 1996 "
(Hereinafter, referred to as a third conventional example), in order to realize a high-speed and wideband wireless communication array antenna,
An optically controlled multi-beam forming apparatus using spatial light signal processing as a beam forming apparatus has been proposed. However, the second conventional example described above has a problem that the technology of the third conventional example cannot be applied.

An object of the present invention is to solve the above problems, to have a simpler structure than the conventional example, to be able to handle a wideband signal without requiring a reference signal, and to provide a third conventional example. An object of the present invention is to provide an array antenna control device to which the above-mentioned light control type multi-beam forming device can be applied.

[0011]

According to a first aspect of the present invention, there is provided an array antenna control apparatus for controlling an array antenna including a plurality of antenna elements arranged in close proximity in a predetermined arrangement shape. In the array antenna control apparatus, a plurality of received signals received by each of the antenna elements of the array antenna are A / D converted into a plurality of digital received signals and output, and output from the converting means A first method of performing downsampling processing on a plurality of digital reception signals at a predetermined rate and outputting a plurality of digital signals after processing
And a plurality of digital reception signals output from the conversion means, respectively, having a plurality of P predetermined transfer functions H ₁ (z) to H _P (z) different from each other. Then, down-sampling processing is performed at the above-mentioned rate on the first band-pass filtering means for dividing and outputting the band and a plurality of digital signals outputted from the first band-pass filtering means. hand,
A second down-sampler means for outputting a plurality of digital signals after the processing, a plurality of digital signals output from the second down-sampler means being distributed to a plurality of Ps respectively, and the first band-pass filtering means Weight adding means for multiplying each of the digital signals by a predetermined weighting factor w ₁ ^{(m) to} w _L ^(m) and adding the digital signals to output a plurality of P digital signals; Up-sampler means for performing up-sampling processing at a predetermined rate on each of the plurality of P digital signals output from the load adding means, and outputting the processed plurality of P digital signals; each of the plurality P number of digital signals output from the sampler unit, different P number of predetermined transfer function G ₁ to one another (z) to the band-pass said a G _P (z) A second band-pass filtering means for outputting a plurality of P digital signals, and a plurality of P digital signals output from the second band-pass filtering means, and receiving a signal resulting from the addition. The main beam of the array antenna is directed to a desired direction of a desired wave by using a constant modulus algorithm based on a plurality of digital signals output from the adding means for outputting as a signal and the plurality of digital signals output from the first downsampler means. And the weighting factor w ₁ for the plurality of input digital signals so as to make the reception level in the direction of arrival of unnecessary waves such as interference waves zero.
^{(m) to} w _L ^(m) are calculated and output to the load adding means, thereby updating and setting the load coefficients w ₁ ^{(m) to} w _L ^(m) . The transfer functions H ₁ (z) to H _P (z) of the first band-pass filtering means and the second
Transfer functions G ₁ (z) to G _P (z) of the band-pass filtering means
Is set such that the digital signal output from the A / D conversion means is substantially satisfied with a perfect reconstruction condition such that the digital signal is reproduced as a reception signal output from the addition means. .

According to a second aspect of the present invention, there is provided the array antenna control device according to the first aspect, wherein the first antenna is inserted between the first downsampler means and the adaptive control means. And a second selecting means inserted between the second downsampler means and the load adding means, wherein the first selecting means is provided from the first downsampler means. The plurality of output digital signals are compared with a predetermined threshold value, a digital signal equal to or more than the threshold value is selected and output to the application control means, and the digital signal corresponding to the selected digital signal is selected. The digital signal output from the second downsampler is selected and the second selector is controlled so as to output the digital signal to the load adder.

Further, according to a third aspect of the present invention, in the array antenna control device according to the first or second aspect, each antenna element of the array antenna is provided before the A / D conversion means. Generating a plurality of beam signals each having a main beam in a plurality of predetermined directions based on the plurality of received signals respectively received by the A / D conversion means as a plurality of digital signals. And a multi-beam forming means for outputting the multi-beam data to the multi-beam.

[0014]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing a configuration of an array antenna control device according to an embodiment of the present invention. FIG. 2 is a block diagram showing a configuration of a band division / combination type adaptive array circuit 9 of FIG. FIG.

In this embodiment, the signal received by the array antenna 100 is A / D-converted into a digital signal, and then band division and downsampling are performed to reduce the speed of adaptive digital beamforming signal processing. In order to be able to handle signals, C
A band division and synthesis processing circuit is introduced into an adaptive array circuit using the M algorithm. In many cases, band division and synthesis-type array signal processing target a signal having a wide relative bandwidth (for example, refer to F. Lorenzelli, et al., “Broadband array proces.
sing using subband techniques ", Proceedings of IEEE
International Conference Acoustic Speech, Signal P
rocessing, pp. 2876-2879, 1996. " In this embodiment, a case is considered in which the signal itself is broadband but the fractional bandwidth is narrow. For example, a case where the signal bandwidth is about 200 MHz and the carrier frequency is 10 GHz or more.
At this time, the fractional bandwidth is 2% or less, and can be regarded as a narrow fractional bandwidth. The purpose is to form a beam adaptively for an ultra-wideband signal in combination with an analog multi-beamformer 2 such as an optically controlled array antenna. An optically controlled array antenna is easy to form a fixed beam for an ultra-wideband signal, but it is difficult to perform adaptive beam forming. On the other hand, it is difficult to perform digital signal processing on ultra wideband signals as they are. So, for example,
A / D by forming multiple beams with an optically controlled array antenna
By performing band division after the conversion, down-converting the sampling frequency to a level at which digital signal processing can be performed, and then performing adaptive beam forming processing, it is possible to adaptively form a beam for an ultra-wide band signal.
This embodiment is a kind of beam space type configuration. As described above, the band division adaptive array circuit is extremely useful when high-speed operation is required.

Next, the configuration and operation of the control device for the array antenna will be described with reference to FIG. The array antenna 100 includes, for example, a plurality of N antenna elements 1-1 to 1-N arranged on one straight line at an interval of, for example, a half wavelength. In the array antenna 100, the plurality of N antenna elements 1-1 to 1-N may be arranged close to each other at a predetermined interval in a two-dimensional predetermined arrangement shape. A transmission signal from a partner transmitting station is input at an incident angle θ defined with respect to a straight line perpendicular to a straight line in which a plurality of N antenna elements 1-1 to 1-N are juxtaposed, and array antenna 100 Received at. The received signals received by each of the antenna elements 1-1 to 1-N are input to the multi-beamformer 2. The multi-beamformer 2 is described in, for example, the prior art document 6 “MISkolnik,“ Introduction to
Rader Systems ", MacGraw-Hill, Inc., pp. 310-318, 1981.
Using a known analog multi-beam forming method using a phase shifter, an adder, or a Butler matrix disclosed in "Year", a predetermined plurality of N ' N ′ beam signals each having a main beam in the direction (or incidence angle) (each beam signal has a beam electric field value in the predetermined plurality of N ′ directions (or incidence angles)). Signal) to generate the down-converter 3-
1 to 3-N '. Here, N ′ is set to N or less in advance. Further, the multi-beamformer 2 may be, for example, a third conventional light-controlled multi-beamformer.

Each of the down-converters 3-1 to 3-N 'down-converts the input beam signal into a signal of a predetermined intermediate frequency (hereinafter, referred to as an IF signal), and outputs the IF / IF signal.
Output to the IQ converters 4-1 to 4-N '. Then I
Each of the F / IQ converters 4-1 through 4-N ′ uses two local oscillation signals orthogonal to each other to
A signal is converted into an I signal and a Q signal
/ D converters 5-1 to 5-N '. Furthermore, A
Each of the / D converters 5-1 to 5-N 'performs A / D conversion on the input I signal and Q signal to convert them into a digital I signal and a digital Q signal, and converts them into a band-pass filter (hereinafter, referred to as a "pass filter").
It is called BPF. ) 6-1-1 to 6-1-P, 6-2-
1 to 6-2-P, ..., 6-N'-1 to 6-N'-P
And the downsamplers 10-1 to 10-1
-N '. In FIG. 1 and FIG.
Indicates a complex signal composed of an I signal and a Q signal that are orthogonal to each other. Here, the digital I signal and digital Q signal output from the A / D converter 5-1 are:
Each of them is distributed (P + 1) and a plurality of P BPF6-
1-1 to 6-1-P and input to the downsampler 10-1. Hereinafter, similarly, A /
The digital I signal and the digital Q signal output from the D converter 5-n (n = 2, 3,..., N ′) are respectively (P + 1) distributed, and a plurality of P BPFs 6-n−1 to 6 are provided. -N-P and the down sampler 1
0-n.

Each of the P BPFs 6-n-1 to 6-n-P
(N = 1, 2,..., N ′) have P different pass bands (hereinafter, referred to as bands 1 to P), that is, different transfer functions H ₁ (z), H ₂ ( z),
... has a H _P (z), for example, a finite impulse response (FIR) transversal digital filter, by band-pass-filters the digital I signal is input and the digital Q signal, P number of bands After the division, when D is an integer of 2 or more, a downsampler 7-np (p = 1, 2,...) That performs a downsampling process on the input signal at a rate of 1 / D
P) to the selector 8. On the other hand, each of the downsamplers 10-1 to 10-N 'receives a predetermined 1
The input signal is down-sampled at a rate of / D, and the processed digital I signal and digital Q signal are output to the selector 11. The selector 11 includes a plurality of N ′ comparators, calculates the power values of the inputted N ′ complex number signals, and calculates L complex number signals (L ≦ L) larger than a predetermined threshold value. N ′, and the L complex number signals are composed of L I signals and L Q signals.) And output them to the CMA control circuit 12 as digital signals S ′ _{1 to} S ′ _L. Also, the selector 11
Is a selector 8 corresponding to the selected L complex number signals.
The selector 8 is interlocked and controlled to select the complex signal to Therefore, the selector 8 outputs the 2P × L complex numbers signals S ₁ to S _L, which is selected to correspond to the selector 11 to the band-dividing and synthesizing type adaptive array circuit 9. By providing the selectors 8 and 11, the adaptive control processing is performed based on a larger signal, so that the accuracy of the adaptive control processing is improved. In the present embodiment, the selector 11 performs the comparison at the power value level, but the present invention is not limited to this, and the comparison may be performed at the signal strength value level or the signal electric field value level.

Of the 2P complex number signals S ₁ , the band 1 complex number signal S ₁ is supplied to the multiplier 24 in the weight addition circuit 20-1.
-1 is input to the adder 25-1, and the complex signal S1 of the band ₁ is added to the adder 25-2 via the multiplier 24-2-1 in the weight addition circuit 20-2. Similarly, the complex number signal S ₁ of the band p (3 ≦ p ≦ P) is input to the multiplier 24-p in the weight addition circuit 20-p.
The signal is input to the adder 25-p via p-1. Also, 2
P multipliers 24 of the complex signal S ₂ is weighted addition circuit 20-p bands p of complex signal _{S 2 (1 ≦ p ≦ P} )
-P-2 is input to the adder 25-p. Further, in the same manner, through a complex signal S _p to the multiplier 24-p-P of weighted addition circuit 20-p bands p (1 ≦ p ≦ P) of 2P complex numbers signal S _P added Table 25-
p. That is, the complex number signals S _{1 to} S _P output from the selector 8 are input to the weight addition circuit 20-p for each band p and subjected to weight addition. Each multiplier 24-
The weighting factor that is a multiplication factor of 1-1 to 24-PL is
As will be described in detail later, the calculation is performed by the CMA control circuit 12 and updated and set. Here, the multiplier 24-1-
, 24-P-1,..., 24-P-1 have the same weighting factor w ₁ ^(m) , and the multipliers 24-1-2, 24-2-2,.
, 24-P-2 have the same weighting factor w ₂ ^(m) , and similarly, multipliers 24-1-1, 24-2-1,.
−P−1 (3 ≦ l ≦ L) have the same load coefficient w _l ^(m) .

In the CMA control circuit 12, the CM
Using an algorithm, multiple L-number of complex signals S ₁ inputted ', S _2', ..., on the basis of the S _L ', directing the main beam of the array antenna in a desired direction of the desired wave and such interference A plurality of L weighting coefficients w _n ^(m) (n = 1, 2,..., L) are calculated for the received signal corresponding to each beam such that the received level in the arrival direction of the unnecessary wave is set to zero. That is,
This CM algorithm is a communication method using a signal wave of a desired wave having a constant envelope, and converts a waveform of an envelope changed by the influence of an unnecessary wave such as an interference wave into a desired shape by converting the waveform of the unnecessary wave. The reception level in the radiation pattern of the array antenna in the arrival direction is set to zero.

The adder 25-1 adds and outputs the input L complex number signals, and outputs the complex number signal output from the adder 25-1 with a predetermined D number with respect to the input plural number signal.
Up-sampler 21-1 that executes up-sampling processing on an input signal at a rate of
₁ (z) is output to the adder 23 via the BPF 22-1. The adder 25-2 adds and outputs the input L complex number signals, and outputs the complex number signal output from the adder 25-2 at a predetermined D rate with respect to the input plural number signals. Up-sampler 21-2 for executing an up-sampling process on an input signal and a transfer function G ₂
The signal is output to the adder 23 via the BPF 22-2 having (z). Hereinafter, similarly, the adder 25-p (3 ≦ p ≦
P) adds and outputs the input L complex number signals,
The complex number signal output from the adder 25-p is converted into an up-sampler 21-p and a transfer function G _p (up-sampler 21-p for executing an up-sampling process on an input signal at a predetermined D rate for a plurality of input signals. BPF22- having z)
Output to the adder 23 via p. Here, P BPs
F22-1 to 22-P have different P number of pass bands, i.e., different transfer functions G ₁ to one another (z),
G ₂ (z), ..., have a G _P (z), for example, a finite impulse response (FIR) transversal digital filter, and a digital I signal and the digital Q signal input to the band-pass Output. Adder 23
Sums the input P complex number signals to obtain the received signal z
Output as (k).

The transfer functions H of N '× P BPFs 6-n-1 to 6-n-P (n = 1, 2,..., N')
_{1 (z), H 2 (} z), ..., and H _P (z), BPF22-
Transfer functions G ₁ (z), G ₂ (z),.
G A _P (z), 1 single 3 is a principle diagram of the received signal, the input signal u _n (k) is the received signal z from the adder 23 is directly reproduced as the same signal
_In order to be output as _n (k), a known perfect reconstruction condition (Prior Art Document 7, "Hitoshi Kiya," Multi-rate signal processing ", Section 7.2, pp. 113-115, Shokodo, 19
1995. ) Is set to be substantially satisfied. If the perfect reconstruction condition is satisfied, in FIG. 1, for example, digital signals output from the A / D converters 5-1 to 5-N 'are reproduced as they are from the adder 23 and output as received signals. You. Note that, as is well known, the perfect reconstruction condition can be divided into an aliasing avoidance condition and an all-pass condition, and it is necessary to satisfy both conditions (see the above-mentioned related art document 7). here,
The former condition is a condition for setting a frequency for avoiding aliasing, and the latter condition is a condition that an all-pass characteristic of an amplitude gain of 1 when a signal passes, that is, a condition that an amplitude is constant. .

In the control device of the array antenna shown in FIG. 1, the multi-beamformer 2, down converters 3-1 to 3-N ', IF / IQ converters 4-1 to 4-N', and selectors 8 and 11 are designed. It may be omitted depending on conditions. If the multi-beamformer 2 and the selectors 8 and 11 are omitted, an adaptive array antenna having an element space configuration is obtained. In this case, L = N in FIGS.
Becomes

Further, the multipliers 24-1-1 to 24-P
The method of calculating the load coefficients w ₁ ^(m) , w ₂ ^(m) ,..., W _L ^(m) of _−L will be described below. In the present embodiment, FIG.
As shown in (1), the weighting factor is updated using the CM algorithm after the band division of P divisions and the downsampling (or decimation) processing. Therefore, the update of the weight coefficient is performed for every D samples at the rate before downsampling.
In the present embodiment, since the specific bandwidth of the signal is narrow, the weighting factor of each band is the same. After the product-sum operation of the signal and the load in each band, the signal is synthesized by the upsampler and the synthesis filter bank, and returned to the original sampling rate. C
In deriving the weight coefficient update formula by the M algorithm,
The following assumptions are made. (A) The band division filter bank and the synthesis filter bank satisfy the perfect reconstruction condition in the FIR type. (B) The load coefficient for each band is the same. (C) In deriving the gradient function of the evaluation function, the load coefficient is stationary.

The evaluation function J of the CM algorithm is

It is assumed that J = (1/4) E [｛| z (k) | ² −σ ² ｝ ² ]. Here, z (k) is the adaptive array circuit 9
Is an output signal from the adder 23, σ is a desired envelope value, and E [•] is a time average. Let k be a symbol representing time at the sampling rate before downsampling (equal to the sampling rate at the A / D converters 5-1 to 5-N '), and m be a symbol representing time at a rate after downsampling. I do. When the downsampling ratio (also called the decimation ratio) is D,
For k = 0, D, 2D,..., m = k / D = 0, 1,
Corresponds to 2, ... Update of the weighting factor is performed at the sampling rate after downsampling. Here, if the steepest descent method is used for updating the load coefficient, the load coefficient update formula is as follows.

[0027]

## EQU2 ## W ^{(m + 1)} = W ^(m) −μ∇ _W J

## EQU3 ## W ^(m) = [w ₁ ^(m) , w ₂ ^(m) ,..., W _L ^(m) ] ^T

４ _W J = [∂J / ∂w ₁ ^(m) , ∂J / ∂w ₂ ^(m) ,
.., ∂J / ∂w _L ^(m) ] ^T where m is the step size and ∇ _W J is the gradient vector for the J vector W ^(m) . Received signal z
Suppose that (k) can be expressed as:

## EQU5 ## z (k) = Z (k) ^T W ^(m) where:

Z (k) = [z ₁ (k), z ₂ (k),... Z _L (k)] ^T

At this time, the gradient vector ∇ _W J is

_７W J = (１ ／) E [{| z (k) | ² −σ ² }} _W {W ^{(m) H} Z (k) ^* Z (k) ^T W ^(m) } ] = E [｛| z (k) | ² −σ ² ｝ Z (k) ^* Z (k) ^T W ^(m) ] = E [｛| z (k) | ² −σ ² ｝ z (k) Z (k) ^* ]. Here, * given to the right side of a vector or matrix is the complex conjugate of each element of the vector or matrix, and H represents conjugate transpose. Assuming that the instantaneous estimated value is used instead of the time average in the above equations 2 and 7, the above equation 2 becomes as follows.

W ^{(m + 1)} = W ^(m) −μ ｛| z (k) | ² −σ ² ｝ z
(K) Z (k) ^*

Next, a vector Z (k) of the received signal is obtained. Using the symbols in FIGS. 2 and 3,

(Equation 9) Here, Q = ｛q | k−q = 0, D, 2D,...｝ ∩ ｛q | q =
0,1, ..., M-1}

Here, g _p (q) (p = 1, 2,...,
P; q = 0, 1,..., M−1) is the impulse response of the band-pass filter G _p (z) forming the synthesis filter bank, and M is the impulse response length. The weight _coefficient value w _n ^(m) appearing in Equation 9 is a constant value during the calculation of the output signal z (k) for a certain time k. That is,

(Equation 10) In obtaining the sum of, k−q = (m−1)
For D, (m−2) D,..., The past load _coefficient values w _n ^(m−1) , w _n ^(m−2) ,... Should be used, but instead, k−q = (M-1) D, (m-2) D,..., W _n ^(m) is also used. This does not actually cause any inconvenience.

In the above equation 5,

[Equation 11] Then, Equation 9 can be written in the form of Equation 5.

In FIG. 3 showing a principle diagram, v _1n (m),
_{v 2n (m), ...,} v Pn (m) , the signal u obtained by converting the signals received by antenna elements 1-n to the digital I / Q signal
_n (k) is converted to a band-pass filter group H ₁ (z), H
₂ (z), ..., (3,. Indicated by 6-n-1 to _{6-n-P) H P} (z) when it is to be noted that signal Deki down sampled band division by , Z
The received signal _n (k) can be interpreted as the output signal of the configuration diagram of FIG. FIG. 3 is a principle diagram in which the analysis filter bank and the synthesis filter bank used in FIGS. 1 and 2 are directly connected. Accordingly, if the filter bank satisfies the perfect reconstruction condition, the received signal z _n (k) is the input signal u _n (k)
Is delayed by a certain time. Bandpass filter H _P (z), if G _P (z) both FIR type digital filter of the filter length M, the time delay is M-1. Therefore,

The [number 12] _{z n (k) = u k} (k-M + 1). That is,

Z (k) = [u ₁ (k−M + 1), u ₂ (k−
M + 1),..., U _L (k−M + 1)] ^T.

The above equation (9) represents the past load _coefficient values w _n ^(m-1) ,
Since w _n ^(m−2) ,... are not used directly, they are slightly different from the output signal of the adaptive array circuit 9 strictly. Therefore,
When z (k) in Equation 5 is rewritten as zh (k), Equation 8 is obtained.
The formula for updating the load coefficient is

W ^{(m + 1)} = W ^(m) −μ ｛| zh (k) | ² −
σ ² ｝ zh (k) Z (k) ^*

Hh (k) = Z (k) W ^(m) = [u ₁ (k−M + 1), u ₂ (k−M + 1),..., U _L (k−M + 1)] W ^(m) k = 0, D, 2D,...; M = k / D. This is the weight coefficient update formula in the adaptive array antenna control device using the band division synthesis type CM algorithm to be obtained. Without using the output signal z of the adaptive array circuit 9 (k), for thereby directly generate zh (k) from the load factor analysis updates the course filter bank input signal u _n (k), adaptive array circuit 9
There is no feedback from the output signal of. This greatly simplifies the circuit configuration.

According to the present embodiment configured as described above, it is possible to adaptively form a beam for an extremely wide band signal. Therefore, the configuration is simpler than that of the conventional example, it can handle a wideband signal without requiring a reference signal, and the third conventional light-controlled multi-beam forming apparatus can be applied. An array antenna control device can be provided.

[0035]

FIG. 4 is a graph of an example of a simulation result of the control device of the array antenna shown in FIG. 1, and is a graph showing a relative received power with respect to an incident angle, showing an operation result of an adaptive array. In this embodiment, an example of an array antenna control device using a half-wavelength-spaced linear array antenna of N = 4 elements will be described. Each antenna element is isotropic. The signal is a QPSK signal that is not band-limited, and the desired wave has an incident angle θ = 20 ° (SNR = 20 dB);
An interference wave enters from an incident angle θ = −40 ° (INR = 17 dB). The filter bank is a fully reconstructed DFT filter bank with a 4-split downsampling ratio of 4,
₁ (z) = 1 + z- ¹ + z- ² + z- ³ . The transfer function of another filter can be automatically determined (Prior Art Document 7, "Hitoshi Kiya," Multi-rate signal processing ", 8.1).
Clause, pp. 128-134, Shokodo, 1995 ". ). FIG. 4 shows that at the rate before downsampling,
The directional characteristics after 00 samples are shown. As is clear from FIG. 4, it can be seen that a null is formed in the −40 ° direction of the incident direction of the interference wave.

[0036]

As described above in detail, in the array antenna control device according to the first aspect of the present invention, an array antenna composed of a predetermined plurality of antenna elements closely arranged in a predetermined arrangement shape is provided. A control unit for controlling the array antenna for controlling, a conversion unit for A / D converting a plurality of reception signals received by each antenna element of the array antenna into a plurality of digital reception signals and outputting the digital reception signals; First downsampler means for executing downsampling processing at a predetermined rate for each of the plurality of output digital received signals and outputting the processed plurality of digital signals, and output from the conversion means The plurality of digital reception signals are respectively converted into a plurality of P predetermined transfer functions H ₁ (z) to H _P different from each other.
A first band-pass filtering means for performing band-pass filtering with (z) and dividing and outputting, and a plurality of digital signals output from the first band-pass filtering means. A second downsampler means for executing a downsampling process at the above-mentioned rate and outputting a plurality of digital signals after the processing, and a plurality of digital signals output from the second downsampler means, respectively, Distribution, multiplying each digital signal by a predetermined weighting factor w ₁ ^{(m) to} w _L ^(m) for each band of the first band-pass filtering means, and adding the digital signals. Up-sampling processing is performed at a predetermined rate on each of the load adding means for outputting P digital signals and the plurality of P digital signals output from the load adding means, and An up sampler for outputting a plurality P number of digital signals, each of the plurality P number of digital signals output from the up-sampler means, different P number of predetermined transfer function G ₁ to one another (z) to G
_A second band-pass filtering unit that performs band-pass filtering with _P (z) and outputs a plurality of P digital signals; and a plurality of P-band digital signals output from the second band-pass filtering unit. And a constant modulus algorithm based on a plurality of digital signals output from the first downsampler means, and an adding means for adding the digital signals of The weighting factor w ₁ ^(m) for the plurality of input digital signals so that the main beam of the array antenna is directed in a desired direction of a desired wave and the reception level in the arrival direction of an unnecessary wave such as an interference wave is made zero. ⁾ to by by calculating w _L ^(m) and outputs it to the weighted addition unit, the load coefficient w ₁ ^(m) through w _L ^(m)
Adaptive control means for updating and setting the transfer functions H ₁ (z) to H _P (z) of the first band-pass filtering means.
And the transfer function G ₁ (z) of the second band-pass filtering means.
G _p (z) is set so as to substantially satisfy a perfect reconstruction condition such that a digital signal output from the A / D conversion means is reproduced as a reception signal output from the addition means. You. Therefore, adaptive beamforming can be performed on an extremely wide band signal. Therefore,
The configuration is simpler than that of the conventional example, it can handle a wideband signal without the need for a reference signal, and the third
It is possible to provide an array antenna control device to which the conventional light-controlled multi-beam forming device of the above can be applied.

According to a second aspect of the present invention, there is provided an array antenna control apparatus according to the first aspect, further comprising an array antenna inserted between the first downsampler means and the adaptive control means. (1) selecting means, and second selecting means inserted between the second down-sampler means and the load adding means.
Selecting means for comparing a plurality of digital signals output from the first downsampler means with a predetermined threshold value, selecting a digital signal equal to or greater than the threshold value, and outputting the selected digital signal to the application control means. At the same time, the second selection means is controlled so as to select a digital signal corresponding to the selected digital signal and output from the second downsampler means and to output the digital signal to the load adding means. Therefore, by providing the first and second selection means,
Since the adaptive control process is performed based on a larger signal, the accuracy of the adaptive control process can be improved.

Further, in the array antenna control device according to the third aspect of the present invention, in the array antenna control device according to the first or second aspect, each antenna of the array antenna is provided before the A / D conversion means. A plurality of beam signals each having a main beam are generated in a plurality of predetermined directions based on a plurality of reception signals respectively received by the elements, and the A / D conversion is performed as a plurality of digital signals. The apparatus further comprises a multi-beam forming means for outputting the data to the means. Therefore, adaptive beamforming can be performed for a very wide multi-beam wideband signal. Therefore, the configuration is simpler than the conventional example,
It is possible to provide an array antenna control device which can handle a wideband signal without requiring a reference signal, and to which the third conventional light-controlled multi-beam forming device can be applied.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an array antenna control device according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a band division and synthesis type adaptive array circuit 9 of FIG.

FIG. 3 is a block diagram for explaining the operation principle of the array antenna control device of the present embodiment.

FIG. 4 is a graph of relative received power with respect to an incident angle, showing an operation result of an adaptive array, which is an example of a simulation result of the control device of the array antenna of FIG. 1;

[Explanation of symbols]

1-1 to 1-N: antenna element, 2: multi-beamformer, 3-1 to 3-N ': down converter, 4-1 to 4-N': IF / IQ converter, 5-1 to 5 -N ': A / D converter, 6-1-1 to 6-N'-P: Band-pass filter (BP
F), 7-1-1 to 7-N'-P, 10-1 to 10-N '
... downsampler, 8, 11 selector, 9 ... band division synthesis type adaptive array circuit, 12 ... CMA control circuit, 20-1 to 20-P ... weight addition circuit, 21-1 to 21-P ... downsampler, 22 -1 to 22-P: band-pass filter (BPF), 23: adder, 24-1-1 to 24-PL: multiplier, 25-1 to 25-P: adder, 100: array antenna.

Claims (3)

[Claims] 1. An array antenna control device for controlling an array antenna comprising a plurality of antenna elements arranged in close proximity in a predetermined arrangement shape, wherein each of the plurality of antenna elements is received by each antenna element of the array antenna. The plurality of received signals are converted to a plurality of digital received signals by A /
A conversion unit for performing D-conversion and outputting, and a plurality of digital reception signals output from the conversion unit, each of which performs downsampling processing at a predetermined rate and outputs a plurality of digital signals after the processing. 1 down-sampler means, and a plurality of P predetermined transfer functions H different from each other,
_First band-pass filtering means for performing band-pass filtering with ₁ (z) to H _P (z) and outputting the divided bands, and output from the first band-pass filtering means Second downsampler means for performing downsampling processing on the plurality of digital signals at the above-described rate and outputting a plurality of digital signals after the processing, and a plurality of output signals from the second downsampler means Are divided into a plurality of P signals, and the respective digital signals are multiplied by predetermined weighting factors w ₁ ^{(m) to} w _L ^(m) for each band of the first band-pass filtering means. Weighted addition means for outputting a plurality of P digital signals, and an upsampling process at a predetermined rate for each of the plurality of P digital signals output from the load addition means. Run the upsampler means for outputting a plurality P number of digital signal after processing, a plurality P number of digital signals, respectively, different P number of predetermined transfer function G ₁ to one another output from the up-sampler means ( z) second band-pass filtering means for performing band-pass filtering with G _P (z) and outputting a plurality of P digital signals; and output from the second band-pass filtering means. Adding means for adding a plurality of P digital signals and outputting a signal of the addition result as a received signal; and a constant modulus signal based on the plurality of digital signals output from the first downsampler means.
An algorithm is used to direct the main beam of the array antenna to a desired direction of a desired wave and to reduce the reception level in the direction of arrival of an unnecessary wave such as an interference wave to the above-mentioned plurality of input digital signals. Coefficients w ₁ ^{(m) to} w
Adaptive control means for calculating and outputting _L ^(m) to the load adding means to update and set the load coefficients w ₁ ^{(m) to} w _L ^(m) ; The transfer functions H ₁ (z) to H _P (z) of the passing filtering means and the transfer functions G ₁ (z) to G _P (z) of the second band-pass filtering means correspond to the A / D. An array antenna control device set so as to substantially satisfy a perfect reconstruction condition such that a digital signal output from the conversion means is reproduced as a reception signal output from the addition means. 2. The array antenna control device according to claim 1, wherein: a first selecting means inserted between said first downsampler means and said adaptive control means; and said second downsampler means. And a second selecting means inserted between the load adding means and the first adding means, wherein the first selecting means converts a plurality of digital signals output from the first downsampler means into a predetermined signal. A digital signal output from the second downsampler means corresponding to the selected digital signal while selecting a digital signal equal to or greater than the threshold value and outputting the digital signal to the application control means; And controlling the second selecting means so as to output the selected signal to the load adding means. 3. The array antenna control device according to claim 1, wherein said array antenna control device is provided in front of said A / D conversion means and is based on a plurality of reception signals received by each antenna element of said array antenna. Multi-beam forming means for generating a plurality of predetermined beam signals each having a main beam in a plurality of predetermined directions and outputting the plurality of digital beam signals to the A / D conversion means. A control device for an array antenna, comprising: