JP2002261669A - Antenna signal processing device - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To realize an antenna signal processing device capable of performing simultaneous and simultaneous space-time equalization with a simpler configuration than conventional. SOLUTION: An adaptive array antenna (AAA) including an antenna element 1, a combiner 2, and a combiner 3 is provided.
In the antenna signal processing apparatus which performs space equalization by using a time equalizer including a delay element 4, a combiner 5, and a combiner 6 connected in series, and taps the output of the antenna with the time equalizer (For example, c ₀ (i)) is set to a fixed value (for example, 1), so that one signal is obtained from the difference signal e (i) between the output Z (i) of the time equalizer and the reference r (i). The weight coefficient for the AAA and the tap coefficient for the time equalizer can be simultaneously and simultaneously calculated by the weight controller 8.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention belongs to the technical field of an adaptive array antenna used in a mobile communication base station or a mobile station.

[0002]

2. Description of the Related Art In order to realize high-quality multimedia mobile communication, it is necessary to have a technique for widening a transmission signal band by increasing a transmission speed and a technique for overcoming a decrease in reception level due to an increase in transmission frequency. Becomes As one of the techniques, there is a space-time equalizer in which an adaptive array antenna (AAA) that performs signal processing on a spatial axis and an adaptive equalizer that performs signal processing on a time axis are combined. By applying this technique, a batch processing method as shown in FIG. 2 and a separation processing method as shown in FIG. 3 have been conventionally proposed.

In the batch processing system shown in FIG.
A delay line 10 with a tap is provided for each, and a weighting coefficient (also referred to as a tap coefficient or a weight control signal) for a plurality of taps (not shown in the drawing) of each delay line with a tap.
Are collectively calculated at the same time, so that optimum reception characteristics can be expected. On the other hand, in the separation processing system shown in FIG. 3, a tapped delay line 10 is provided after an adaptive array antenna (AAA) including an antenna element 1, a combiner (also referred to as a complex multiplier and a variable complex weighting device) 2 and a combiner 3. In this configuration, the number of taps of the tapped delay line 10 is independent of the number of antenna elements, so that the total number of taps can be reduced as compared with the batch processing method.

In either system, a signal processed by the output of the space-time equalizer (the output of the synthesizer 6 in FIG. 2 and the output of the tapped delay line 10 in FIG. 3) is added to a weight controller (also referred to as a weight controller). LMS (Least Mean S)
quare least squares method or RLS (Recursive Least Squa
re using a recursive least squares) optimization algorithm
A tap coefficient that minimizes the root mean square error between the reference signal and the output of the space-time equalizer is calculated and transmitted.

[0005]

However, in the collective processing method shown in FIG. 2, a weight (weight) of (the number of antenna elements) × (the number of taps of a delay line with taps) is required in order to perform adaptive processing. There is a problem that the size is increased and the cost is increased.

In addition, the separation processing system shown in FIG. 3 requires two sets of weight processing units for updating weights, and operates as an AAA and a decision feedback sequence estimator (DD) in a training section.
FSE) to converge the tap coefficients, then estimate the reference signal from the maximum sequence estimation, and then fix the AAA tap coefficients to converge the FFF and DDFSE tap coefficients. However, there is a problem that the advantage of the batch update is lost.

SUMMARY OF THE INVENTION An object of the present invention is to provide an antenna signal having both the advantages of batch update of the batch processing system and simplification of the configuration and cost reduction of the separation processing system. An object of the present invention is to provide a processing device.

[0008]

In order to achieve the above object, a first configuration of an antenna signal processing apparatus according to the present invention comprises:
It is characterized by having the following components. (B) a plurality of antenna elements arranged at different positions in space (b) provided corresponding to each antenna element, receiving a weight control signal, and determining the amplitude and phase of a radio wave reception signal for each antenna element First variable complex weighting device that variably outputs (c) A first combiner that combines the outputs of the first variable complex weighting devices (d) The output of the first combiner is delayed stepwise A plurality of delay elements connected in series, and (e) provided in correspondence with the signal having a delay time of zero and each of the delay signals sequentially delayed by each of the delay elements. Variable complex weighting device that variably outputs the amplitude and phase of the second variable complex weighting device (f) a second combiner that combines the outputs of the second variable complex weighting devices (g) a predetermined reference signal and a second The difference signal from the output signal of the synthesizer A weighting control signal that minimizes the root-mean-square error between the reference signal and the output signal of the second combiner by using an optimization algorithm; Each second excluding
Weight control device which sends a fixed value signal to each of the two variable complex weighting devices, which has been excluded, and simultaneously sends the fixed value signals to one of the second variable complex weighting devices.

A second configuration is characterized in that, in the first configuration, a second variable complex weighting device to which the fixed value signal is to be sent is provided for the signal having the delay time of zero. This is an antenna signal processing device.

In a third configuration, a signal is directly connected to a second combiner without providing a second variable complex weighting device for transmitting a fixed value signal in the first configuration or the second configuration,
An antenna signal processing device is characterized in that a fixed value signal is not sent from a weight control device.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In the embodiment of the present invention, an AAA output comprising an antenna element 1, a combiner 2, and a combiner 3 similar to the separation processing system shown in FIG. 3 is provided to a tapped delay line and each tap. To the time equalizer (linear equalizer) composed of a combiner and a synthesizer, and the difference between the output and the reference signal is subjected to the LMS (Least Mean Square Least Squares) method or RLS (Recursive Least Square Recursive Minimum 2). When calculating a weighting coefficient (tap coefficient: transmitted as a weighting control signal) to be sent to each combiner of the AAA and each combiner of the time equalizer by using an optimization algorithm such as the multiplication method, as described later, the AAA is used. The term of the product of the tap coefficients of the time equalizer and the tap coefficients of the time equalizer appears, so the number of tap coefficients that are variables (unknowns) becomes one more than the number of equations, and the solution (tap) Can not be obtained in a batch number). For this reason, conventionally, two weight controllers are provided as shown in FIG. 3 so that the tap coefficient for AAA and the tap coefficient for the time equalizer are separately processed in time. One of the tap coefficients (variables) for the time equalizer is a fixed value, that is, a known number, and the variables and the number of equations are made equal to collectively calculate the variables.

By doing so, the number of taps to be weighted can be greatly reduced as compared with the conventional batch processing method (FIG. 2), and the number of taps divided in time can be reduced as in the conventional separation processing method (FIG. 3). It is possible to collectively obtain the tap coefficients without performing the system weight processing, and the equalization by the AAA and the equalization by the time equalizer can be simultaneously performed.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing the configuration of the embodiment of the present invention. In FIG. 1, an adaptive array of M antenna elements 1 and M combiners 2 (first variable complex weighting device, which may also be expressed as a tap) and a combiner 3 (first combiner) are shown. An antenna (AAA) is configured.

Further, p number of delay elements 4 and taps between them and p number of combiners 5 provided at the final output
The (second variable complex weighting device) and the combiner 6 (second combiner) constitute a time equalizer (linear equalizer).

In this embodiment, the output of the AAA, that is, the output of the output y (i) (i represents the time) of the synthesizer 3 is branched and directly coupled to the synthesizer 6. This means that the weighting coefficient (tap coefficient) for a signal having a delay time of zero is set to 1, that is, the amplitude and phase are not weighted. Therefore, the signal is directly connected to the combiner 6 without providing the combiner 5. This is an example. As a general form, the combiner 5 also exists here, and the tap coefficient c ₀ (i) is input.

Hereinafter, the general form will be described first. Now, the input from each antenna element 1 is x _n (i) (n = 1 to M), and the tap coefficient input to each combiner 2 is w _n (i)
Then, the input signal vector X of the AAA and the tap weight vector W of the AAA are represented by Expressions 1 and 2.

[0017]

X (i) = [x ₁ (i), x ₂ (i),..., X _M (i)] ^T

[0018]

W (i) = [w ₁ (i), w ₂ (i),..., W _M (i)] ^T

T stands for transposition. Then, time i
The output y (i) of the AAA at is represented by Equation 3.

[0020]

Y (i) = W ^H (i) · X (i)

H is a Hermitian matrix. Next, the input vector Y (i) and the tap weight vector C (i) of the time equalizer (linear equalizer) are expressed by Expressions 4 and 5. Here, c _n (i) (n = 0 to p) is a tap coefficient, and p is the number of taps.

[0022]

## EQU4 ## Y (i) = [y (i-1), y (i-2),...
…, Y (ip)] ^T

[0023]

C (i) = [c ₀ (i), c ₁ (i), c ₂ (i),...
……, c _p (i)] ^T

Now, regarding the space-time equalization at time i, when all the input signal vectors U (i) and the tap weight vectors H are expressed by equations, the following equations 6 and 7 are obtained.

[0025]

U (i) = [x ₁ (i), x ₂ (i),..., X _M (i),
y (i-1), y (i-2), ..., y (ip)] ^T

[0026]

H (i) = [w ₁ (i) c ₀ (i), w ₂ (i) c ₀ (i),
..., W _M (i) c ₀ (i), c ₁ (i), c ₂ (i),.
_P (i)] ^T

Therefore, the output signal Z (i) of the second combiner
Is represented by Expression 8.

[0028]

## EQU8 ## Z (i) = H ^H (i) · U (i)

The error signal vector e (i) is expressed by Expression 9.

[0030]

(Equation 9)

The mean square error is

[0032]

| E (i) | ² = {r (i) −H ^H (i) U (i)} · {r ^* (i) −H ^T (i) U ^* (i)} = E [ ^{| r (i) | 2]} -H T r * ur -H H r ur + H H R uu H

## EQU1 ## The following equation is obtained from the condition of the minimum mean square error.

[0034]

[ _Mathematical formula-see original _document ] r _ur = R _uu H _opt

Here,

[0036]

R _uu = E [U (i) · U (i) ^H ]

[0037]

R _ur = E [U (i) · r (i) ^* ]

R (i) is a reference signal. Further H
_opt is a tap coefficient that minimizes the mean square error. Equation 11 shows the variables (w ₁ ,..., W _M , c ₀ ,...) Of M + p + 1.
As can be seen from Equations 6 and 12, R _uu is a matrix of (M + p) rows and (M + p) columns for c _P ).
There are only p equations and no solution can be obtained.

Therefore, in the present invention, one of the variables is set to a fixed value, and the variables, that is, tap coefficients are collectively calculated by making the number of the remaining variables equal to the number of equations. This is performed by the weight controller 8 (weight control device). Theoretically, no matter which variable is fixed,
Further, other variables can be collectively calculated as any fixed value. In this embodiment (FIG. 1), the tap coefficient c ₀ (i) for a signal having a delay time of zero is set to a fixed value of 1. is there. Since a fixed value of 1 means that no weighting is applied to both the amplitude and the phase,
As a result, the combiner 5 becomes unnecessary, and a signal is directly sent to the synthesizer 6.

At this time, the equation (11) is a simultaneous linear equation with tap coefficients as unknowns, and various linear solutions can be utilized, and the solution can be obtained more easily. Here, the method of obtaining the tap coefficients as the solution of the simultaneous equations has been described. However, the calculation of the actual tap coefficients is usually performed by applying a sequential optimization algorithm such as LMS or RLS which is a high-speed calculation method.

[0041]

As described above, according to the antenna signal processing apparatus of the present invention, in the configuration including the AAA and the time equalizer of one system, one of the tap coefficients for the time equalizer is set to a fixed value. By doing so, the tap coefficients for the remaining AAA and the tap coefficients for the time equalizer can be collectively calculated, so that the equalization by the AAA and the equalization by the time equalizer can be simultaneously performed by one system of weight processing. As a result, with a simpler configuration than the conventional method,
There is an advantage that unnecessary waves can be removed at high speed in a multiplex wave environment in which the level fluctuation of a required wave exists.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment of an antenna signal processing device of the present invention.

FIG. 2 is a block diagram showing a configuration of a conventional batch processing type antenna signal processing apparatus.

FIG. 3 is a block diagram showing a configuration of a conventional antenna signal processing device of a separation processing system.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 antenna element 2 combiner 3 combiner 4 delay element 5 combiner 6 combiner 7 adder 8 weight controller 9 weight controller 10 delay line with tap 11 reference signal generator 12 decision feedback sequence estimator

Continued on the front page (72) Inventor Shigeki Obote 4-2-1-1, Nakanarisawa-cho, Hitachi City, Ibaraki Pref. 4-12-1, Machi, Ibaraki University Faculty of Engineering, Department of Media and Communication Engineering, Electromagnetic Wave Systems Laboratory (72) Inventor Yasuhiro Kazama 5-1-1 Shimorenjaku, Mitaka-shi, Tokyo Japan F-term (reference) 5J021 AA05 AA06 CA06 DB02 DB03 EA04 FA14 FA15 FA16 FA17 FA20 FA29 FA32 GA02 HA05 5K059 AA08 BB08 CC03 CC04 DD37

Claims (3)

[Claims] 1. An antenna signal processing device comprising the following components. (B) a plurality of antenna elements arranged at different positions in space (b) provided corresponding to each antenna element, receiving a weight control signal, and determining the amplitude and phase of a radio wave reception signal for each antenna element First variable complex weighting device that variably outputs (c) A first combiner that combines the outputs of the first variable complex weighting devices (d) The output of the first combiner is delayed stepwise A plurality of delay elements connected in series, and (e) provided in correspondence with the signal having a delay time of zero and each of the delay signals sequentially delayed by each of the delay elements. Variable complex weighting device that variably outputs the amplitude and phase of the second variable complex weighting device (f) a second combiner that combines the outputs of the second variable complex weighting devices (g) a predetermined reference signal and a second The difference signal from the output signal of the synthesizer A weighting control signal that minimizes the root mean square error between the reference signal and the output signal of the second combiner using an optimization algorithm as the power and the first variable complex weighting device and the predetermined 1 Each second excluding
Weight control device for sending a fixed value signal simultaneously to one of the second variable complex weighting devices excluded from the above, 2. The configuration according to claim 1, wherein a second variable complex weighting device to which the fixed value signal is to be sent is provided for the signal having the delay time of zero. 2. The antenna signal processing device according to 1. 3. A signal according to claim 1 or 2, wherein a signal is directly connected to a second combiner without providing a second variable complex weighting device for transmitting a fixed value signal, and Is an antenna signal processing device characterized by not transmitting a fixed value signal.