JP3416865B2 - Adaptive antenna device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to directivity control and waveform equalization of an antenna for a wireless communication system or an antenna for a measurement system.

[0002]

2. Description of the Related Art FIG. 8 shows a conventional configuration. The figure shows an example of an adaptive antenna apparatus having a decision feedback equalizer as a method for suppressing a multipath interference wave.

The N-element antennas 8011 to 801n and the adaptive array filter 802, which are installed at half wavelength intervals of the radio frequency, form an adaptive array antenna. The output of the adaptive array filter 802 is combined with the output of the rear filter 803 by the combiner 805 and input to the decision unit 804. The rear filter is a non-linear filter having a decision output as an input, and performs so-called decision feedback equalization. Adaptive array
The filter and the backward filter operate under the root mean square (MMSE) control of the decision error signal output by the subtractor 806. Therefore, the common control of the adaptive array and the adaptive equalization by one root mean square error (MSE) evaluation function is performed.

[0004]

However, in the conventional configuration, since the delay time is not adaptively controlled, the number of delay means is increased and the hardware becomes complicated. In addition, since the number of delay units increases, the number of samples required for convergence of the weight increases.

An object of the present invention is to provide an adaptive antenna device having a small number of delay means, simple hardware, and capable of suppressing multipath interference waves.

[0006]

Means for Solving the Problems The feature of the present invention for achieving the above object, a plurality of element antennas, the output of the element antennas (x1 (t) ~xn (t )) to complex weights (W ₁ ~ first weighting means for imposing W _n), weight control device for controlling the weight of the weighting means, the output of element antennas (x1 (t) ~xn
(t)) first branching means for inputting the weighting means and the weight control device, a reference signal generator, a reference signal
The second branching means for branching (d (t)) into a plurality of parts, the delay time of the incoming wave with respect to the branched reference signal (d (t))
First delay means for imposing different delays (T _{d1 to} T _dm ) determined together, and reference signals (d (t-T _d1 ) to d (t-T _dm ) delayed by the first delay means. )) With complex weights (W _d1
~ W _dm ) , for combining a complex-weighted signal on the outputs of the multi-element antennas and a complex-weighted signal of the reference signals delayed by different delay times. And a third branching means for branching the output of the combiner into the output of the adaptive antenna device and the input to the delay time control device, and the delay time in the plurality of first delay means ( A delay time control device for automatically controlling T _{d1 to} T _dm ) , and
The delay time control device uses an adaptive antenna whose input signal is the output signal of the combiner.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram showing a first embodiment,
It shows a form in which an adaptive antenna receiving apparatus is configured by using n reference antennas and n antenna elements and m first delay means. In this figure, reference numerals 1011 to 101n
Is an antenna element, 1021 to 102n are first branching means connected to the antenna elements 1011 to 101n, 10
31 to 103n are weighting means for weighting the outputs of the antenna elements 1011 to 101n, 104 is a reference signal generator, 105 is a second branching means for branching the reference signal into a plurality, and 1061 to 106m are the reference signals. First delay means for delaying, 1071 to 107m are second weighting means for weighting the delayed reference signal, 1
Reference numeral 08 is a weight control device for determining the weights of the first weighting means 1031 to 103n and the second weighting means 1071 to 107m, and 109 is the first delay means 1061.
Delay time control device for determining a delay time of ~ 106 m, 1
Reference numeral 10 is a combiner, and 111 is a third branching means for branching the output of the combiner.

As shown in the figure, the weight control device 108 receives the outputs of the antenna elements 1011 to 101n and a reference signal. Further, the output of the combiner 110 is input to the delay time control device 109. The input signals to the weight control device 108 and the delay time control device 109 are implemented by either RF, IF or baseband.

FIG. 2 is a diagram showing an internal configuration of the delay time control device 109. In this figure, reference numeral 201 is a correlation matrix forming means, 202 is an eigenvalue / eigenvector computing means, 203 is a delay time and power estimating means, and 204 is a delay time determining means.

First delay means 1061 to 106 to be used
The number m of m and the delay times Td1 to Tdm set in the first delay means 1061 to 106m are determined as follows, for example.

The frequency f is defined as f ₀ −KΔf to f ₀ + KΔf
When swept up to (f ₀ : center frequency, Δf: swing width, K: positive integer), the output of the synthesizer 110 at each frequency is input to the correlation matrix forming means 201 in the delay time control device 109, The correlation matrix of the output of the combiner at each frequency is output, and the output is input to the eigenvalue / eigenvector calculating means 202 and the delay time / power estimating means 203, and the eigenvalue and eigenvector obtained by the eigenvalue / eigenvector calculating means 202 are delayed. It is input to the time and power estimation means 203. The eigenvectors of the correlation matrix represent the incoming wave and the internal noise. Since the internal noise has no correlation with each incoming wave, the eigenvector representing the internal noise is orthogonal to the vector representing each incoming wave. Further, the eigenvalue represents the level of the incoming wave and the internal noise, and if the level of the internal noise is lower than that of each incoming wave, the eigenvector representing the internal noise can be estimated from the value of the eigenvalue. Therefore, the delay time and power estimation means 203 estimates the delay time and power of the incoming wave from the eigenvalues and eigenvectors of the correlation matrix. The estimated delay time and power of the incoming wave are input to the delay time determining means 204, and the number m of delay means to be used is set as the number of incoming waves whose power exceeds the threshold value, and is set in the first delay means 1061 to 106m. Delay time Td1 to T
dm is determined according to the delay time of the incoming wave.

With this configuration, it is possible to suppress the multipath wave by optimizing the number of delay units used and the delay time set in the delay units.

When the delay time set in the first delay means 1061 to 106m is determined, the weights w1 to wn and the weighting means 1071 to 107 weighted by the first weighting means 1031 to 103n in the weight control device 108.
The weights wd1 to wdm weighted by m are

[0015]

[Equation 1]

Is determined to satisfy However,

[0017]

[Equation 2]

It is Where d (t) is the reference signal, x1
(T), ..., Xn (t) are reception waveforms of the antenna elements,
E {·} is the expected value, * is the complex conjugate number, T is the transposed matrix, ￣
Represents the average.

Next, a second embodiment of the present invention will be described.

FIG. 3 is a view showing the second embodiment,
The reference signal is obtained by decision feedback. The same components as those described in FIG. 1 are designated by the same reference numerals and the description thereof will be omitted.

In this figure, reference numeral 301 is a judging device, and reference numeral 302 is a fifth branching device for branching the output of the third branching device 111 into two, an input of the delay time control device 109 and an input of the judging device 301. is there. The output of the determiner 301 is input to the weight controller 108 as a reference signal. With such a configuration, since the demodulated signal is used instead of the reference signal, the reference signal generator is not necessary.

Next, a third embodiment of the present invention will be described.

FIG. 4 is a diagram showing the third embodiment,
In this configuration, the reference signal is formed by the determiner, and the weight is updated based on the error signal from the reference signal. In addition, in FIG.
Regarding the same components as those explained in FIG. 3,
The same reference numerals are given and the description thereof is omitted.

In the figure, 401 is a subtractor.
The difference between the output of the determiner and the output of the adaptive antenna device is obtained by the subtractor 401 and input to the weight controller. In the weight control device, for example, LMS (Least Mean)
The value of the weight is obtained by the Square algorithm. With such a configuration, the weight can be updated based on the error signal.

Next, a fourth embodiment of the present invention will be described.

FIG. 5 is a diagram showing the fourth embodiment,
Using an A / D converter that is slower than the transmission speed of wireless communication,
The reference signal is obtained by decision feedback. The same components as those described in FIG. 1 and FIGS. 3 to 4 are designated by the same reference numerals and the description thereof will be omitted.

In this figure, reference numerals 5011 to 501n
Is an amplifier, 5021 to 502n are down converters, 5
031 to 503n and 505 are A / D converters, 50
Reference numerals 41 to 504n denote delay means for adjusting the timing of the input from the antenna element portion and the output of the adaptive antenna device.
Reference numeral 06 is a data extraction device. Delay means 1061-10
A delay time of a symbol length unit is set to 6 m, and the data extraction device sets the output of the determiner and the delay means 1061 to 106 m at a timing matched with the speed of input from the A / D converter to the weight control device. The delay time signal is extracted and is input to the weight control device 108. With this configuration, the adaptive antenna device can be configured even when an A / D converter slower than the transmission rate of wireless communication is used.

Next explained is the fifth embodiment of the invention.

FIG. 6 is a flow chart showing the fifth embodiment, which is a control method for estimating the delay time after operating the adaptive antenna device without using the delay means. First, the quality is improved (62) using only the first weighting means. Next, the delay time of the delayed wave that cannot be suppressed by the first weighting means is estimated, and the delay time of the delay means is determined (66). With this control method, it is possible to accurately estimate the delay time and power of an incoming wave that is difficult to suppress when operating without using delay means.

Next, a sixth embodiment of the present invention will be described.

FIG. 7 is a diagram showing the sixth embodiment,
The configuration is such that transmission is performed using the delay time and the weight described in the first embodiment. The same components as those described in FIG. 1 are designated by the same reference numerals and the description thereof will be omitted.

In this figure, reference numeral 701 is a transmission signal generator, reference numeral 702 is a fourth branching means, reference numerals 7031 to 7031.
Reference numeral 703m is a second delay means, reference numerals 7041 to 704m are third weighting means, reference numeral 705 is a combiner, reference numeral 706.
Is a fifth branching means, reference numerals 7071 to 707n are fourth weighting means, and reference numeral 708 is a weight correction device. The delay time determined by the delay time control device 109 at the time of reception is set in the second delay means 7031 to 703m, and the weight control device 108 is determined at the time of reception in the third weighting means 7041 to 704m. Weight is set. In the fourth weighting means 7071 to 707n, weights obtained by correcting the weights determined by the weight control device 108 at the time of reception to the transmission frequency by the weight correction device 708 are set. The output of the transmission signal generator 701 is branched into a plurality by the second branching unit 702, one of which is input to the combiner 705, the other is input to the delaying units 7031 to 703m, and the second weighting unit 7041 to. After being weighted by 704m,
It is input to the synthesizer 705. The output of the combiner 705 is output by the fifth branching means 706 to the fourth weighting means 70.
71 to 707n, weighted, and then input to the antenna elements 1011 to 101n. With such a configuration, it is possible to suppress multipath waves even in transmission.

[0033]

The adaptive antenna device of the present invention adaptively changes the delay time to minimize the number of delay means and optimize the delay time even when an interference wave exists in the desired wave direction. Thus, it is possible to suppress the interference wave. Therefore, the weight can be converged with a small number of samples.

[Brief description of drawings]

FIG. 1 is a diagram showing a first embodiment of the present invention.

FIG. 2 is a diagram showing a delay time control device 7 according to the first embodiment of the present invention.

FIG. 3 is a diagram showing a second embodiment of the present invention.

FIG. 4 is a diagram showing a third embodiment of the present invention.

FIG. 5 is a diagram showing a fourth embodiment of the present invention.

FIG. 6 is a diagram showing a fifth embodiment of the present invention.

FIG. 7 is a flowchart showing a sixth embodiment of the present invention.

FIG. 8 is a diagram showing an example of an antenna device using a conventional decision feedback equalizer.

[Explanation of symbols]

1011 to 101n antenna element 1021-102n First branching means 1031 to 103n First weighting means 104 Reference signal generator 105 Second branching means 1061 to 106m First delay means 1071 to 107m Second weighting means 108 Weight control device 109 delay time control device 110 synthesizer 111 Third branching means 201 Correlation matrix forming means 202 Eigenvalue and eigenvector operation means 203 Delay time and power estimation means 204 means for determining delay time 301 Judgment device 302 fifth branching means 401 Subtractor 5011-501n amplifier 5021 to 502n Down converter 5031-503n, 505 A / D converter 5041-504n delay means 506 Data extraction device 701 transmission signal generator 702 Fourth branching means 7031-703m Second delay means 7041-704m Third weighting means 705 synthesizer 706 Fifth branching means 7071 to 707n Fourth weighting means 708 Weight correction device 8011 to 801n antenna element 802 Adaptive array filter 803 Rear filter 804 Judgment device 805 synthesizer 806 Subtractor

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-6-164434 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H01Q 3/26

Claims (5)

(57) [Claims] 1. A plurality of element antennas, and complex weights for outputs (x1 (t) to xn (t)) of the element antennas.
A first weighting means for imposing (W _{1 to} W _n ) , a weight control device for controlling the weight of the weighting means, and the output (x1 (t) to xn (t)) of the element antenna to the weighting means. first branching means and a reference signal generator, the reference signal a second branching means for branching (d (t)) into a plurality for inputting to the weight control unit
And the delay of the incoming wave with respect to the branched reference signal (d (t))
Different delays (T _{d1 to} T _dm ) determined according to time
A first delay means for imposing a reference signal delayed by said first delay means (d (t-
T _d1) and the second weighting means for imposing ~d (t-T _dm)) to complex weights (W _d1 ~W _dm), the multi-element signals the complex weighting to the antenna output and the plurality of reference signals Synthesizer for synthesizing complex weighted signals delayed by different delay times
And a third branching means for branching the output of the combiner into two, an output of the adaptive antenna device and an input to the delay time control device, the delay time (T _d1 ~ T
An adaptive antenna device comprising delay time control means for automatically controlling _dm ) , and the delay time control means uses the output signal of the combiner as an input signal. 2. The adaptive antenna apparatus according to claim 1, wherein the delay time control means obtains a correlation matrix from an output at each frequency of the synthesizer, and an eigenvalue having the correlation matrix as an input. And an eigenvector calculating means, a correlation matrix and its eigenvalue, a delay time and power estimating means for inputting an eigenvector, and a delay time determining means for inputting this delay time and power. 3. The adaptive antenna device according to claim 1, further comprising an A / D converter that samples a signal input to the weight control device and the delay time control device for each integer symbol. Adaptive antenna device. 4. The adaptive antenna apparatus according to any one of claims 1 to 3, wherein an output of the combiner is determined by a determiner to be a reference signal. 5. A plurality of element antennas, the first weighting means for imposing the output of the element antennas (x1 (t) ~xn (t )) to complex weights (W ₁ ~W _n), the element antenna output (X1 (t)
~ Xn (t)) to the weighting means and the weight control device, a first branching means, a reference signal generator, and a second branching means for branching the reference signal (d (t)) into a plurality. When,
Delay of incoming wave with respect to the branched reference signal (d (t))
Different delays (T _{d1 to} T _dm ) determined according to time
, A delay time control device for controlling the delay time set in the delay means, and reference signals (d (t-T _d1 ) to d (t ) delayed by the first delay means. -T _dm ))
Second weighting means for imposing complex weights (W _{d1 to} W _dm ) on the output, a weight control device for controlling the weights of the first and second weighting means, and a complex-weighted signal for the outputs of the multi-element antennas. And a first synthesizer for synthesizing a complex weighted signal obtained by delaying the plurality of reference signals with different delay times, and delaying the output of the first synthesizer from the output of the adaptive antenna device. A receiving circuit section composed of third branching means for branching into two inputs to the time control device, a transmission signal generator, and fourth branching means for branching the output of the transmission signal generator into a plurality of outputs. , A plurality of second delay means connected to the fourth branch means and having a delay time determined by a delay time control device in reception, and a complex weight is imposed on the output of the second delay means. Third weighting means and the third weighting A second combiner for combining the output means,
The transmitting means comprises a fifth branching means for branching the output of the second combiner and a fourth weighting means for weighting the signal branched by the fifth branching means, and at the time of reception. The value of the first and second weights determined in the above is corrected to the transmission frequency to be the value of the weights of the fourth and third weighting means, and the fourth weighting means is input to a plurality of antenna elements, An adaptive antenna device configured to perform transmission.