JPH11284423A - Adaptive antenna system and antenna exciting method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an optimum weight of each antenna and to reduce the probability of forming an interference signal wave beam by obtaining an evaluation function to evaluate distortion in amplitude of a received signal, based on an array output signal and its envelope generated by a synthesis means and by updating the weight of each antenna. SOLUTION: First a correlation matrix calculation device 12 calculates a correlation matrix Rxx(m) from a received signal X(i), a correlation vector calculation device 13 calculates a correlation vector rxd (m) from the received signal X(i) and a reference signal d(i), and an initial weight calculation device 14 calculates a weight W(1) in an initial stage from the correlation matrix Rxx(m) and the correlation vector rxd (m). Then a weight setting device 15 calculates an envelope value Y(i), obtains an evaluation function Q(n) from an array output signal Y(n) and the envelope value Y(i) while reception is started, and updates a weight (n), based on the evaluation function Q(n) and this processing is repeated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an adaptive antenna device for forming a beam on a desired signal wave and suppressing distortion of the desired signal wave, and an antenna excitation method.

[0002]

2. Description of the Related Art FIG. 5 shows, for example, "Adaptive Array for Suppressing Multiple Waves (CS87-12 of IEICE Technical Report)"
FIG. 2 is a configuration diagram showing a conventional signal receiving apparatus shown in the monthly publication, in which A _{1 to} A _k are element antennas constituting an adaptive antenna, and B _{1 to} B _k are element antennas A ₁
To A _k received signal X ₁ to X _k received by (hereinafter, but to represent the received signal X ₁ to X _k using X (n), X
(N) is a vector representation of the received signal, which indicates the received signal at time n), and is an A / D converter for analog-to-digital conversion, and C _{1 to} C _k are A / D converters B ₁ .about.B _k each received signal is converted into a digital signal X (n) weights W ₁ to _W-k (hereinafter, the will be expressed using the weight W ₁ to _W-k W a (n), W (n)
Is a vector representation of the weight, and indicates the weight at time n). The weighting unit ₁ multiplies the multiplication results of the weighting units C _{1 to} C _k to synthesize an array output signal Y
The adder 2 outputs (n) the received signal X from the array output signal Y (n) output from the adder 1 and the envelope value σ.
An evaluation function Q (n) for evaluating the distortion of the amplitude of (n) is obtained, and the element antenna A ₁ is determined based on the evaluation function Q (n).
A signal processing unit that updates the weight W (n) of A _k .

Next, the operation will be described. First, as shown in FIG. 6A, the element antennas A _{1 to} A _k form a beam on a modulated signal wave having a constant envelope value (for example, a modulated signal wave by FM, PSK, or the like) to obtain a desired signal. For example, even if the modulated signal waves are transmitted from the same oscillating source, the modulated signal wave f ₂ is changed to the modulated signal wave f ₂ because the propagation path is different as shown in FIG. _The signal may be received by the adaptive antenna later in time than ₁ .

In this case, the modulated signal wave f ₁ and the modulated signal wave f
_{Since two} different phases (see FIG. 6 (a), the FIG. 6 (b)), the envelope value of the composite wave of the modulated signal wave f ₁ and the modulation signal wave f ₂ is changed (FIG. 6 (c) ), The reception accuracy of a modulated signal wave having a constant envelope value is degraded.

Therefore, in order to prevent the reception accuracy from deteriorating,
First, the signal processing unit 2 obtains an evaluation function Q (n) for evaluating the distortion of the amplitude of the received signals X (n) received by the element antennas A _{1 to} A _k . Specifically, the evaluation function Q (n) is obtained by substituting the array output signal Y (n) and the envelope value σ output from the adder 1 into the following equation. In addition,
Assuming that the incoming wave having the highest power is the desired signal wave, the envelope value σ is set in accordance with the power. Q (n) = (|| Y (n) | ^{p-? P} | ^q ) where p and q are usually integers of 1 or 2.

[0006] Then, the signal processing unit 2 calculates the evaluation function Q
When (n) is obtained, the weight W (n) of the received signal X (n) is updated based on the evaluation function Q (n) in order to minimize the amplitude distortion of the received signal X (n). Specifically, as shown below, the evaluation function Q (n) is
(N), and the next weight W (n + 1) is determined using the differential result 微分_W Q (n). W (n + 1) = W (n) −μ · ▽ _W Q (n) where μ is a step size (evaluation step size)

The weight W (n) is a vector indicating the weights W _{1 to} W _k at time n. In the initial stage, a standardized constant is set, and an example is shown below. W ₁ = 1 W ₂ = 0 W ₃ = 0 _Wk = 0

As a result, the weighting performed by the weighting units C _{1 to} C _k next time is the updated weight W (n +
1), and the distortion of the amplitude of the received signal X (n) is minimized. Further, even if an interference signal wave having lower power than the desired signal wave arrives, the interference signal wave is suppressed.

[0009]

Since the conventional signal receiving apparatus is configured as described above, the weight W (n) for minimizing the distortion of the amplitude of the received signal X (n) is sequentially updated. Since the weight W (1) in the initial stage is set to a standardized constant, there is a problem that it takes a long time to obtain the optimum weight W (n). In addition, since an optimum weight W (n) cannot be obtained quickly, when an interference signal wave having power larger than the desired signal wave arrives, the desired signal wave is suppressed, and a beam may be formed in the interference signal wave. There was an issue. Further, the envelope value σ is set assuming that the arriving wave having the maximum power is the desired signal wave. However, since the envelope value σ is set by calculation, the accuracy of the envelope value σ is low, and the optimal weight There was also a problem that it was difficult to obtain W (n).

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and it is possible to quickly obtain an optimum weight, and even if an interference signal wave having a power larger than that of a desired signal wave arrives, the interference is reduced. An object of the present invention is to provide an adaptive antenna device and an antenna excitation method that can reduce the probability that a beam is formed in a signal wave.

[0011]

SUMMARY OF THE INVENTION An adaptive antenna apparatus according to the present invention determines an initial stage weight of each antenna from received signals and reference signals received by a plurality of antennas, and determines the initial stage weight and reception level. An envelope value is determined from a signal.

The adaptive antenna apparatus according to the present invention obtains an evaluation function for evaluating the distortion of the amplitude of the received signal from the current array output signal and the previous array output signal generated by the combining means, and based on the evaluation function. The weight of each antenna is updated.

An adaptive antenna apparatus according to the present invention determines an initial stage weight of each antenna from a received signal received by a plurality of antennas and a reference signal, and determines a current array output signal generated by a combining unit and a previous array output signal. An evaluation function for evaluating the distortion of the amplitude of the received signal is obtained from the array output signal, and the weight of each antenna is updated based on the evaluation function.

In the adaptive antenna apparatus according to the present invention, when the evaluation function indicates that the distortion of the amplitude of the received signal has increased from the previous time, the step size is reduced and the weight of each antenna is updated again. It was made.

According to the antenna excitation method of the present invention, an initial stage weight of each antenna is determined from received signals and reference signals received by a plurality of antennas, and an envelope value is determined from the initial stage weight and the received signal. The decision is made.

In the antenna excitation method according to the present invention, an evaluation function for evaluating distortion of the amplitude of a received signal is obtained from an array output signal generated this time and an array output signal generated last time, and each antenna is determined based on the evaluation function. Is updated.

An antenna excitation method according to the present invention determines an initial stage weight of each antenna from received signals received by a plurality of antennas and a reference signal, and simultaneously generates an array output signal generated this time and an array output signal generated last time. An evaluation function for evaluating the distortion of the amplitude of the received signal is obtained from the output signal, and the weight of each antenna is updated based on the evaluation function.

According to the antenna excitation method of the present invention, when the evaluation function indicates that the distortion of the amplitude of the received signal has increased from the previous time, the step size is reduced and the weight of each antenna is updated again. It was made.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below. Embodiment 1 FIG. Figure 1 is a block diagram showing an adaptive antenna device according to a first embodiment of the present invention. In the figure, A ₁ to A _k is the element constituting the adaptive antenna antenna (antenna), B ₁ .about.B _k is the antenna elements A ₁
ＡA _k, the received signals X _{1 to} X _k (hereinafter, the received signals X _{1 to} X _k are _represented as X (n), for example, X (n) is a vector representation of the received signal. , Indicating the received signal at time n)
A / D converter for digital conversion, C _{1 to} C _k are A / D
Converter B ₁ .about.B _k weights each received signal is converted into a digital signal X (n) by W ₁ to _W-k (hereinafter,
The weights W _{1 to} W _k are expressed as W (n). For example, W (n) is a vector expression of the weight and indicates the weight at time n. And 11 are adders (synthesizing means) for synthesizing the multiplication results of the weighting units C _{1 to} C _k and outputting an array output signal Y (n).

Reference numeral 12 denotes a correlation matrix R _xx (m) based on the reception signals X (i) received by the element antennas A _{1 to} A _k.
Is a correlation matrix calculator (determining means) for calculating the received signal X (i) received by the element antennas A _{1 to} A _k
And a reference signal d (i) having a correlation with the desired signal wave, a correlation vector calculator (determining means) 14 for calculating a correlation vector r _xd (m), and an inverse matrix 14 of the correlation matrix R _xx (m) An initial weight calculator (determining means) for calculating an initial stage weight W (1) by multiplying R ^-1 _xx (m) by a correlation vector r _xd (m), 15 is provided by element antennas A _{1 to} A _k The received signal X (i) is multiplied by an initial stage weight W (1), and the multiplication results are combined to determine an envelope value Y (1). An evaluation function Q for evaluating the distortion of the amplitude of the received signal X (n) from the array output signal Y (n) and the envelope value Y (1).
(N) is a weight setting unit (determining means, updating means) for updating the weights W (n) of the element antennas A _{1 to} A _k based on the evaluation function Q (n). FIG. 2 is a flowchart showing an antenna excitation method according to the first embodiment of the present invention.

Next, the operation will be described. Before actually receiving the received signal X (n) and outputting the array output signal Y (n), an optimum weight W (n) can be obtained from the beginning of the reception to obtain the following. By performing such preprocessing, the weight W (1) and the envelope value Y (1) at the initial stage are calculated.

First, the correlation matrix calculator 12 calculates the correlation matrix R _xx (m) by substituting the received signals X (i) received by the element antennas A _{1 to} A _k into the following arithmetic expression. (Step ST1). However, the value of m in equation (1) is an arbitrary integer.

[0023]

(Equation 1)

Further, the correlation vector calculator 13 receives the received signals X (i) received by the element antennas A _{1 to} A _k.
And a reference signal d (i) having a correlation with the desired signal wave are substituted into an arithmetic expression shown below to obtain a correlation vector r _xd (m)
Is calculated (step ST2). However, the value of m in the equation (2) is an arbitrary integer.

[0025]

(Equation 2)

When the correlation matrix calculator 12 calculates the correlation matrix R _xx (m) and the correlation vector calculator 13 calculates the correlation vector r _xd (m), the initial weight calculator 14 calculates the correlation matrix R _xx and then calculating the inverse matrix R ^-1 _xx (m) of the (m), the inverse matrix R ^-1 _xx of the correlation matrix _{R xx (m) (m)} ,
The initial stage weight W (1) is calculated by substituting the correlation vector r _xd (m) into the following equation (step ST3). However, the value of m in equation (3) is an arbitrary integer.

W (m) = R ⁻¹ _xx (m) r _xd (m) (3)

When the initial weight calculator 14 determines the weight W (1) in the initial stage, the weight setting unit 15 adds the initial signals to the received signals X (i) received by the element antennas A _{1 to} A _k , respectively. Is multiplied by the weight W (1), and the results of the multiplication are combined to obtain an envelope value Y
(1) is determined (step ST4).

[0029]

(Equation 3)

In this way, the initial stage weight W
When (1) and the envelope value Y (1) are determined, the preprocessing is completed, the reception signal X (n) is actually received, and the reception processing for generating the array output signal Y (n) is started. Step ST5) As described above, even if the desired signal wave is transmitted from the same oscillation source, the envelope value of the array output signal Y (n) is changed due to a time lag caused by passing through different propagation paths. May change. However, in the first reception processing, the weight W calculated in the previous preprocessing is used.
Weighting is performed using (1).

Therefore, in order to prevent the reception accuracy from being deteriorated due to the change in the envelope value, the weight setting unit 15 firstly sets the reception signal X received by the element antennas A _{1 to} A _k.
An evaluation function Q (n) for evaluating the amplitude distortion of (n) is obtained (step ST6). Specifically, the array output signal Y (n) output from the adder 11 and the envelope value Y (1) calculated in the previous preprocessing are substituted into the following arithmetic expression, and the evaluation function Q (n ). Q (n) = (|| Y (n) | ^p- | Y (1) | ^p | ^q ) (5) where p and q are usually integers of 1 or 2.

When the weight setting unit 15 obtains the evaluation function Q (n), the weight setting unit 15 minimizes the distortion of the amplitude of the received signal X (n) based on the evaluation function Q (n). The weight W (n) of (n) is updated (step ST7). Specifically, as shown below, the evaluation function Q
(N) is universally differentiated by the weight W (n), and the next weight W (n + 1) is determined using the differential result ▽ _W Q (n). W (n + 1) = W (n) -μ · ▽ W Q (n) ... (6) However, μ is the step size (step size of the evaluation)

Thus, the weighting units C ₁ -C _k perform the next weighting with the updated weight W (n +
1), and the distortion of the amplitude of the received signal X (n) is minimized. Further, even if an interference signal wave having lower power than the desired signal wave arrives, the interference signal wave is suppressed.

As is apparent from the above, the first embodiment
According to the above, based on the received signal X (i) received by the element antennas A _{1 to} A _k and the reference signal d (i), the element antenna A
_{1 to} A _{k in} the initial stage, and determine the initial stage weight W (1) and the received signal X
Since the configuration is such that the envelope value Y (1) is determined from (i), the optimum weight W (1) can be obtained from the initial stage, and as a result, a beam is formed on the desired signal wave from the initial stage. Therefore, even if an interference signal wave having a power larger than that of the desired signal wave arrives thereafter, there is an effect that the probability that a beam is formed in the interference signal wave can be reduced.

Embodiment 2 In the first embodiment, the array output signal Y (n) output from the adder 11 is always used.
And the envelope value Y (1) calculated in the previous preprocessing,
Although the calculation of the evaluation function Q (n) has been described, FIG.
As shown in step ST11, after the second reception processing, the evaluation function Q (n) is obtained by using the current array output signal Y (n) and the previous array output signal Y (n-1). (In the first reception processing, the current array output signal Y (n) and the envelope value Y (1) are used). Q (n) = (|| Y (n) | ^p- | Y (n-1) | ^p | ^q ) (7) where p and q are usually integers of 1 or 2.

As a result, an evaluation function Q (n) along the currently received desired signal wave can be obtained as compared with the first embodiment, so that even if an interference signal wave having a larger power than the desired signal wave arrives, In addition, there is an effect that the probability that a beam is formed in the interference signal wave can be reduced.

Embodiment 3 In the first and second embodiments, the current array output signal Y (n) and the envelope value Y
(1) Or, an evaluation function Q (n) is obtained using the previous array output signal Y (n-1) and the weight W (n) is updated based on the evaluation function Q (n). However, as shown in FIG. 4, the weight setting unit 15 compares the current evaluation function Q (n) with the previous evaluation function (n-1), and re-calculates the weight W (n) according to the comparison result. It may be updated. Specifically, first, the weight setting unit 15 determines whether or not the amplitude distortion of the received signal X (n) has increased from the previous time (step ST21). That is, if the following inequality holds, it is determined that the amplitude distortion of the received signal X (n) has increased from the previous time. Q (n) ≧ Q (n−1) (8)

When the amplitude distortion has increased from the previous time, the weight setting unit 15 sets the weight W (n)
Is multiplied by a positive constant α smaller than 1.0 (step ST22), and the weight W (n) is updated again (step ST7). ).

Thus, a beam is formed to a desired signal wave to some extent, and when the calculation of the optimum weight W (n) is close to convergence, even if the amplitude distortion of the received signal X (n) increases from the previous time. This has the effect of preventing divergence of the calculation processing.

[0040]

As described above, according to the present invention, the initial stage weight of each antenna is determined from the received signals received by the plurality of antennas and the reference signal, and the initial stage weight and the received signal are determined based on the initial stage weight and the received signal. Since the configuration is such that the envelope value is determined, an optimal weight can be obtained from the initial stage, and as a result, a beam is formed on the desired signal wave from the initial stage. Even if a large interference signal wave arrives, there is an effect that the probability that a beam is formed on the interference signal wave can be reduced.

According to the present invention, an evaluation function for evaluating the distortion of the amplitude of the received signal is obtained from the current array output signal and the previous array output signal generated by the synthesizing means, and each antenna is evaluated based on the evaluation function. Since the weights are configured to be updated, an evaluation function along the currently received desired signal wave can be obtained. As a result, even if an interference signal wave having a higher power than the desired signal wave arrives, the interference signal can be obtained. There is an effect that the probability that a beam is formed in a wave can be reduced.

According to the present invention, the initial stage weight of each antenna is determined from the received signals received by the plurality of antennas and the reference signal, while the current array output signal and the previous array output generated by the combining means are determined. An evaluation function for evaluating the distortion of the amplitude of the received signal from the signal is obtained, and the weight of each antenna is updated based on the evaluation function. As a result, an evaluation function along a desired signal wave can be obtained. As a result, even if an interference signal wave having a higher power than the desired signal wave arrives, the probability that a beam is formed in the interference signal wave can be reduced. effective.

According to the present invention, when the evaluation function indicates that the distortion of the amplitude of the received signal has increased from the previous time, the step size is reduced and the weight of each antenna is updated again. Therefore, when a beam is formed to a desired signal wave to some extent and the calculation processing of the optimum weight is close to convergence, even if the distortion of the amplitude of the received signal increases from the previous time, it is possible to prevent the calculation processing from diverging. effective.

According to the present invention, an initial stage weight of each antenna is determined from received signals and reference signals received by a plurality of antennas, and an envelope value is determined from the initial stage weight and the received signal. Since the optimal weight can be obtained from the initial stage, a beam is formed on the desired signal wave from the initial stage, and thereafter, an interference signal wave having a larger power than the desired signal wave arrives. However, there is an effect that the probability that a beam is formed in the interference signal wave can be reduced.

According to the present invention, an evaluation function for evaluating the amplitude distortion of the received signal is obtained from the currently generated array output signal and the previously generated array output signal, and the weight of each antenna is determined based on the evaluation function. Since it is configured to update, an evaluation function along the currently received desired signal wave can be obtained. As a result, even if an interference signal wave having a larger power than the desired signal wave arrives, the interference signal wave can be obtained. There is an effect that the probability of forming a beam can be reduced.

According to the present invention, the initial stage weight of each antenna is determined from the received signals received by the plurality of antennas and the reference signal, and the weights of the array output signal generated this time and the array output signal generated last time are determined. Since an evaluation function for evaluating the distortion of the amplitude of the received signal is obtained, and the weight of each antenna is updated based on the evaluation function, the optimum weight can be obtained from the initial stage, and the desired reception currently being received can be obtained. As a result, an evaluation function along the signal wave can be obtained. As a result, even when an interference signal wave having a higher power than the desired signal wave arrives, the effect that the probability that a beam is formed in the interference signal wave can be reduced. is there.

According to the present invention, when the evaluation function indicates that the distortion of the amplitude of the received signal has increased from the previous time, the step size is reduced and the weight of each antenna is updated again. Therefore, when a beam is formed to a desired signal wave to some extent and the calculation processing of the optimum weight is close to convergence, even if the distortion of the amplitude of the received signal increases from the previous time, it is possible to prevent the calculation processing from diverging. effective.

[Brief description of the drawings]

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

FIG. 2 is a flowchart illustrating an antenna excitation method according to the first embodiment of the present invention.

FIG. 3 is a flowchart illustrating an antenna excitation method according to a second embodiment of the present invention.

FIG. 4 is a flowchart illustrating an antenna excitation method according to a third embodiment of the present invention.

FIG. 5 is a configuration diagram showing a conventional signal receiving device.

FIG. 6 is an explanatory diagram illustrating a change in an envelope value of a composite wave.

FIG. 7 is an explanatory diagram for explaining a time delay of a modulated signal wave.

[Explanation of symbols]

A _{1 to} A _k element antennas (antennas), C _{1 to} C _k
Weighting section (synthesizing means), 11 adder (synthesizing means),
12 correlation matrix calculator (determining means), 13 correlation vector calculator (determining means), 14 initial weight calculator (determining means), 15 weight setting device (determining means, updating means).

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Isamu Chiba 2-3-2 Marunouchi, Chiyoda-ku, Tokyo Mitsui Electric Co., Ltd. (72) Inventor Hiroshi Kojima 2-3-2 Marunouchi, Chiyoda-ku, Tokyo 3 Inside Ryo Denki Co., Ltd. (72) Koichi Takahara 1-2-1 Shibaura, Minato-ku, Tokyo Inside NTT Central Personal Communication Network Co., Ltd. (72) Hiroyuki Nose 1-chome, Shibaura, Minato-ku, Tokyo No. 2 NTT Central Personal Communication Network Co., Ltd.

Claims (8)

[Claims] A determining means for determining an initial stage weight of each antenna from received signals and reference signals received by a plurality of antennas, and determining an envelope value from the initial stage weight and the received signal; Combining means for multiplying the received signal received by the antenna by a weight, combining the respective multiplication results to generate an array output signal, and calculating the received signal from the array output signal and the envelope value generated by the combining means. An adaptive antenna apparatus comprising: an evaluation function for evaluating an amplitude distortion; and updating means for updating a weight of each antenna based on the evaluation function. 2. A combining means for multiplying reception signals received by a plurality of antennas with respective weights and combining the multiplication results to generate an array output signal, and a current array output generated by the combining means. An adaptive antenna apparatus comprising: an evaluation function for evaluating distortion of amplitude of a received signal from a signal and a previous array output signal; and updating means for updating a weight of each antenna based on the evaluation function. 3. A decision means for deciding an initial stage weight of each antenna from a received signal received by a plurality of antennas and a reference signal, and multiplying a received signal received by each antenna by a weight. Combining means for combining the results to generate an array output signal; and an evaluation function for evaluating the distortion of the amplitude of the received signal from the current array output signal and the previous array output signal generated by the combining means, and evaluating the evaluation function. An adaptive antenna device comprising: updating means for updating the weight of each antenna based on a function. 4. The method according to claim 1, wherein when the evaluation function indicates that the distortion of the amplitude of the received signal has increased from the previous time, the step size is reduced and the weight of each antenna is updated again. The adaptive antenna device according to any one of claims 1 to 3, wherein 5. An initial stage weight of each antenna is determined from a received signal and a reference signal received by a plurality of antennas, and an envelope value is determined from the initial stage weight and a received signal. Each received signal is multiplied by a weight, and the multiplication results are combined to generate an array output signal, and an evaluation function for evaluating the amplitude distortion of the received signal from the array output signal and the envelope value is obtained. An antenna excitation method for updating the weight of each antenna based on the evaluation function. 6. An array output signal is generated by multiplying reception signals received by a plurality of antennas with weights, and combining the multiplication results to generate an array output signal generated this time and an array output signal generated last time. An antenna excitation method for obtaining an evaluation function for evaluating the amplitude distortion of a received signal from a signal and updating the weight of each antenna based on the evaluation function. 7. An initial stage weight of each antenna is determined from a received signal received by a plurality of antennas and a reference signal, and a weight of the received signal received by each antenna is multiplied. Generate an array output signal by synthesizing, find an evaluation function for evaluating the amplitude distortion of the received signal from the currently generated array output signal and the previously generated array output signal, and calculate the weight of each antenna based on the evaluation function. Update the antenna excitation method. 8. The method according to claim 5, wherein when the evaluation function indicates that the distortion of the amplitude of the received signal has increased from the previous time, the step size is reduced and the weight of each antenna is updated again. The antenna excitation method according to any one of claims 1 to 7.