JP2007318407A - Adaptive array antenna apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an adaptive array antenna apparatus capable of receiving desired waves with high gain and suppressing interference waves. <P>SOLUTION: The apparatus includes a weight setting means 105 for correcting a directional vector of a desired wave direction in an array antenna 101 with the use of a plurality of numbers of respectively different arrival signals, so as to generate a plurality of correction directional vectors, calculating a plurality of weights respectively with the use of the correction directional vectors, and selecting the desired weight from the plurality of weights so as to set the weight. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to adaptive array antenna technology, and more particularly to interference wave suppression technology.

  Some adaptive array antennas realize a beam pattern formation that receives a desired wave from a plurality of incoming wave radio waves with high gain and suppresses interference waves. Here, the desired wave is an incoming wave that is desired to be received by the adaptive antenna, and the interference wave is an incoming wave that is not desired to be received by the adaptive antenna. When the desired wave and the interference wave are received at the same time, the signal cannot be restored because of the interference state, but the desired wave signal can be restored by suppressing the interference wave. As an algorithm for realizing such beam pattern formation, a direction-constrained power minimization method that uses the arrival direction of a desired wave as preliminary knowledge is well known.

  However, the problem with this direction-constrained power minimization method is that a high-accuracy beam pattern is generated when the direction vector in the desired wave direction is found very accurately, but there is an error in the direction vector. The pattern is deteriorated.

  When there is an error in the direction vector, the installation environment of the array antenna is uncertain, and there is a scatterer that couples to the antenna element in the vicinity of the array antenna, or the characteristics of the high-frequency cable or receiver connected to the array antenna. Is a case where the temperature changes due to temperature environment or aging, and this cannot be measured. Such a situation will be referred to as a case where calibration (calibration) cannot be performed sufficiently.

  In order to solve such a problem, an algorithm that corrects a direction vector and realizes a desired beam pattern even when calibration cannot be sufficiently performed has been reported (Non-Patent Document 1). This correction calculation is performed using information on the received signal and the number of incoming signals of the array antenna.

However, the number of incoming signals required to perform this correction is generally estimated from the received signal of the array antenna, and can be accurately obtained by the influence of thermal noise, external noise, the number of samples in a finite time, etc. It may not be possible. If there is an error in the number of incoming signals, an error also occurs in the correction calculation, and there is a problem that a desired beam pattern cannot be realized. If a desired beam pattern cannot be realized, high gain reception of a desired wave cannot be performed, and interference wave suppression cannot be performed. As a result, information on the desired wave signal cannot be obtained.
Won Sik Youn and Chong Kwan Un, “Robust adaptive beamforming based on the eigenstructure method,” IEEE Trans. Signal Processing, vol. 42, no. 6, June 1994.

  As described above, in the adaptive array antenna device of the prior art for correcting the direction vector using the arrival direction information, receiving the desired wave with high gain, and forming the beam pattern for suppressing the interference wave, the number of incoming signals When the direction vector is corrected in a state where there is an error, an error occurs in the corrected direction vector, and as a result, there is a problem that a target beam pattern cannot be realized. As a result, there is a problem that high gain reception of desired waves and interference wave suppression cannot be realized.

  The present invention has been made to solve the above problem, and even when there is an error in the number of incoming signals, the direction vector can be corrected with high accuracy, and the intended beam pattern can be formed. It is an object of the present invention to provide an adaptive array antenna. As a result, it is possible to realize high gain reception of desired waves and suppression of interference waves.

An adaptive array antenna apparatus according to an aspect of the present invention includes:
An array antenna for receiving incoming waves,
An arrival signal number setting means for estimating and setting the number of arrival signals of the arrival wave based on the reception signals received by the array antenna;
Direction-of-arrival setting means for estimating and setting the direction of arrival of the incoming wave based on at least the received signal;
Desired wave direction setting means for selecting and setting the arrival direction of the desired arrival wave as the desired wave direction from the set arrival directions of the arrival waves;
A plurality of correction direction vectors are generated by correcting the direction vector of the desired wave direction in the array antenna using a plurality of different numbers of incoming signals, and a plurality of weights are generated using the plurality of correction direction vectors. And a weight setting means for selecting and setting a desired weight from the plurality of weights,
Reception signal output means for combining and outputting the reception signal using the reception signal received by the array antenna and the weight set by the weight setting means.

  According to the adaptive array antenna apparatus of the present invention, it is possible to realize high-gain reception of desired waves and suppression of interference waves.

  Hereinafter, the present embodiment will be described in detail with reference to the drawings.

(1) First Embodiment FIG. 1 is a configuration diagram of an adaptive array antenna apparatus 100 according to a first embodiment. An adaptive array comprising an array antenna 101 for receiving an incoming wave, an incoming signal number setting means 102, an arrival direction setting means 103, a desired wave direction setting means 104, a weight setting means 105, and a received signal output means 106. In the antenna device 100, the weight setting means 105 corrects the direction vector of the desired wave direction under conditions of different numbers of incoming signals, calculates a plurality of weights using the plurality of corrected direction vectors, One of the weights is selected, and the selected weight is set. Hereinafter, each component will be described in order.

  The array antenna 101 that receives an incoming wave is an antenna that can receive an incoming wave. The type of each antenna element is not limited as long as it is an antenna that can receive incoming waves, but if you want to receive incoming waves in a wide angular range, antenna elements with a wide beam width, such as microstrip antennas and monopole antennas. In order to receive an incoming wave in a narrow range, an antenna having a narrow beam width such as a horn antenna or a Yagi-Uda antenna is suitable.

  Further, the arrangement method of the antenna elements and the distance between the antenna elements may be obtained from the direction of the assumed incoming wave and the gain of the array antenna to be realized, and are not particularly limited.

  The received signal received by the array antenna 101 is sent to and calculated by each means (the number of incoming signal setting means 102, the arrival direction setting means 103, the weight setting means 105, and the received signal output means 106) of the adaptive array antenna apparatus 100 described below. The Therefore, although not shown, the received signal is subjected to amplification, frequency conversion, filtering, conversion from an analog signal to a digital signal, etc., as long as each means can easily process the received signal, There are no restrictions on these applications.

Here, the received signal at time t of the array antenna 101 is defined by the following equation (1).

N is the number of antenna elements, and x _i (t) is the received signal at time t of the i-th element.

  The incoming signal number setting means 102 is a means for setting the number of incoming signals received by the array antenna 101. Here, it is assumed that one or a plurality of incoming waves are received by the array antenna 101, and it is necessary to estimate the number of incoming signals from the received signals.

  The method for estimating the number of incoming signals may be performed in accordance with any conventionally used algorithm. For example, a method of estimating from the frequency spectrum of the received signal, a method of estimating by the AIC method or MDL method using eigenvalues of the correlation matrix, and the like can be used.

  Incidentally, the number of incoming signals corresponds to, for example, the number of transmission sources when there are a plurality of transmission sources, but may not correspond to the number of transmission sources.

  The arrival direction setting means 103 is a means for setting the spatial arrival direction of the incoming wave received by the array antenna 101. Here, it is assumed that one or more incoming waves arrive within a predetermined angle and are received by the array antenna 101, and it is necessary to estimate and calculate the arrival direction from the received signal.

  The arrival direction estimation method may be performed according to an arbitrary algorithm conventionally used. For example, a method of estimating from received power when the beam direction is changed, such as a phased array antenna, or a method of estimating using a high-resolution arrival direction estimation algorithm such as the MUSIC method or ESPRIT method can be used. In arrival direction estimation, there is an algorithm that can improve the estimation accuracy when the number of incoming signals is required or when the number of incoming signals is used. In this case, the arrival signal number setting means 102 It is effective to use the set number of incoming signals.

Desired wave direction setting means 104 is means for setting the direction of an incoming wave to be received. Here, the selection of an incoming wave to be received can be arbitrarily performed by an operator, for example, and is selected from the incoming waves set by the arrival direction setting means 103. The following description as to select the arrival direction theta _d. In general, the direction of arrival is represented by two parameters, for example, an elevation angle and an azimuth angle (θ and φ) are used. Here, for the sake of simplicity, the description will be made in the case of a one-dimensional case. The two-dimensional case can be similarly expanded.

  In addition, since the incoming wave other than the desired wave direction set here is an incoming wave that is not desired to be received, it is referred to as an interference wave. As a result of the desired wave direction setting means 104, the incoming wave becomes a desired wave or an interference wave.

  In the weight setting means 105 for setting the weight, in order to realize a beam pattern in which a high gain beam is directed in the desired wave direction set by the desired wave direction setting means 104 and null is suppressed in the other interference wave directions. This is a means for setting the weight. A weight is set for each antenna. The weight setting unit 105 will be described in detail later.

  The received signal output means 106 is a means for combining the received signal received by the array antenna 101 and the weight set by the weight setting means 105 and outputting the combined signal. The synthesis of the received signals is realized by an operation of multiplying the received signals of the respective antennas by weights set for the respective antennas and obtaining the sum thereof.

  As a result, all the incoming signals are included in the signals received by the respective antennas, but only the signals in the desired wave direction are included in the combined received signals. Therefore, it is possible to solve the problem that the received signal cannot be demodulated due to interference. Strictly speaking, the interference wave is not suppressed 100% but is received with a very small gain, and there is a level that is very small compared to the desired wave.

  Next, the weight setting unit 105 will be described in detail. FIG. 2 shows a configuration diagram of the weight setting means 105. Arrival signal number setting means 201 used for correction of a plurality of direction vectors, a plurality of direction vector correction means 202, a plurality of weight calculation means 203, a plurality of gain calculation means 204 for desired wave directions, and a weight selection means 205 It is composed of

  A description will be given of the plurality of incoming signal number setting means 201 used for direction vector correction. The arrival signal number setting means 201 sets a plurality of continuous arrival signal numbers. That is, each arrival signal number setting means 201 sets a different number of unique arrival signals. For example, since an N-element array antenna can handle the maximum number of incoming signals of N−1 waves, the number of incoming signals from 1 to N−1 is set. As a result, it is possible to handle the number of all incoming signals at once. Alternatively, when the maximum number of incoming wave signals is known in advance, the number of incoming signals from 1 to a predetermined maximum number of incoming signals is set. Alternatively, when the minimum number of incoming signals is known in advance, the minimum number of incoming signals to N−1 waves are set. Alternatively, when the maximum number of arrival signals and the minimum number of arrival signals are known in advance, the minimum number of arrival signals to the maximum number of arrival signals are set. By selecting the setting range of the number of incoming signals according to the situation, it is possible to reduce the hardware resources used in the calculation performed by each means and reduce the cost.

Next, the plurality of direction vector correction means 202 will be described. Multiple direction vector correcting unit 202 performs correction calculation direction vector of the desired wave direction theta _d with different number of incoming signals conditions. Here, it is assumed that the array antenna 101 is insufficiently calibrated and has an error in the direction vector.

Here, a method for calculating a correction vector in which the number of incoming signals is set to k will be described. Introduction expressed by Equation (2) below direction vector of the desired wave direction theta _d.

  The direction vector is sometimes called a mode vector or a steering vector, and is a vector determined by the coordinates of the antenna elements and the radiation pattern of each antenna. Here, since the calibration is insufficient, the direction vector is a design value, a value calculated by electromagnetic field simulation, or a value measured in an anechoic chamber, and the direction vector at the place where it is actually installed. The difference is a problem.

The correction calculation is obtained by the following equation (3).

Here, b (θ _d ) is a corrected direction vector. I is an N × N unit matrix, V _N is an N × (N−k) noise subspace matrix, and H is a conjugate complex transpose. The noise subspace V _N is obtained as follows.

First, an N × N correlation matrix Rxx is calculated by the following equation (4) using the received signal.

Here, E [] is an expected value calculation. Any method may be used for the expected value calculation. For example, the expected value can be calculated by the following equation (5) using T received signals at different times.

Next, eigenvalue expansion of the correlation matrix Rxx is performed, and eigenvalues and eigenvectors are expressed as in the following equation (6).

Here, V is represented by the formula (7) in matrix composed N × N eigenvectors v _i.

Further, Λ is an N × N diagonal matrix composed of eigenvalues and is expressed by Expression (8).

Then, the eigenvalues are arranged in descending order as shown in Expression (9).

The noise subspace V _N is defined by equation (10) using equation (7) and the number of incoming signals k.

The corrected direction vector b (θ _d ) is calculated using the above calculation.

  The plurality of direction vector correction means 202 performs the correction calculation of the direction vector using Expression (10) using the number of incoming signals corresponding to each.

Next, the plurality of weight calculation means 203 will be described. Each weight calculation means 203 calculates an N × 1 weight vector by the following equation (11) using the corrected direction vector.

Here, Rxx ⁻¹ represents the inverse matrix of the correlation matrix given by Equation (5). In this way, the plurality of weight calculation means 203 calculate the weights respectively.

Next, the plurality of desired wave direction gain calculation means 204 will be described. As the desired wave direction, the direction of θ _d set by the desired wave direction setting means 104 is selected. Then, the radiation pattern calculation of the adaptive array antenna 101 is performed using the calculated weight, and the gain in the desired wave direction is calculated. The gain in the desired wave direction may be calculated using a generally used adaptive array antenna gain calculation method.

  Next, the weight selection unit 205 will be described. The weight selection means 205 selects the maximum number of incoming signals from one or a plurality of incoming signals corresponding to the case where a gain in the desired wave direction exceeding the threshold is obtained using a preset threshold gain. Then, a weight corresponding to the selected number of incoming signals is selected.

  Thus, in the weight setting means 105, the number of incoming signals setting means 201 used for direction vector correction, the direction vector correction means 202, the weight calculation means 203, and the gain calculation means 204 for the desired wave direction are arranged in parallel. The weight selected by the weight selection means 205 is set.

  As described above, the adaptive array antenna apparatus 100 of the present embodiment is configured. In the following, it is possible to receive a desired wave with a high gain and suppress an interference wave even when calibration according to this embodiment is insufficient and an error occurs in the estimation of the number of incoming signals. Describe the possible effects. In particular, in the present embodiment, description will be made regarding that the direction vector can be corrected with high accuracy even if the number of incoming signals is incorrect.

  Description of the operation of the portion that sets the number of incoming signals, sets the direction of arrival, and sets the desired wave direction using the received signals received by the array antenna 101 is omitted.

  In the following, the principle of selecting the optimum weight in a situation where it is difficult to estimate the number of incoming signals will be described.

  The correction of the direction vector is calculated using the noise subspace matrix expressed by Equation (10). Here, the noise subspace matrix is a matrix determined by the number of incoming signals k. Therefore, when the number of incoming signals k is different, the value of the corrected direction vector changes. That is, it is expected that the weight also changes with the number of incoming signals k, and as a result, the beam pattern of the adaptive array antenna apparatus 100 also changes.

  Therefore, a simulation is performed to show how the gain in the desired wave direction and the gain in the interference wave direction change when the number of incoming signals used for calculating the correction vector is changed. Here, gain means reception sensitivity.

  In FIG. 3, the horizontal axis represents the number of incoming signals used for the direction vector correction calculation, and the vertical axis represents the gain. As a simulation condition, the number of incoming signals is two. Incidentally, here, the omnidirectional gain by a single antenna is set as a reference, that is, 0 dB.

  When the number of incoming signals used for the correction calculation is 2, the gain in the desired wave direction is high, and the gain in the interference wave direction is −20 dB or less, which is sufficiently suppressed.

  On the other hand, when the number of incoming signals used for correction calculation is 1, the gain in the desired wave direction is kept high, but the gain in the interference wave direction is also high, and it is understood that interference wave suppression cannot be performed.

  Also, when the number of incoming signals used for correction calculation is 3 or more, the gain in the interference wave direction is low and the interference wave is suppressed, but the gain in the desired wave direction is also degraded, and high gain reception of the desired wave can be performed. It's gone.

  Thus, it can be confirmed that a desired beam pattern cannot be realized unless the direction vector is corrected using the correct number of incoming signals.

  Further, FIG. 3 also shows that the gain in the desired wave direction and the interference wave direction monotonously decreases as the number of incoming signals increases.

  The inventors clarified the phenomenon shown in FIG. 3 and clarified problems in the prior art. And the weight setting means 105 which can select an optimal weight using the relationship between the number of incoming signals and the gain in FIG. 3 is realized. Here, a gain threshold value is introduced to select the number of incoming signals.

  The method for selecting the weight is to select the maximum number of incoming signals from one or a plurality of incoming signals corresponding to the case where a gain in the desired wave direction exceeding the threshold is obtained, and this selected number of incoming signals. Select the weight corresponding to.

  By selecting the weight in this way, the gain in the desired wave direction can be maintained at a value equal to or higher than the threshold value. Therefore, high gain reception of a desired wave is possible. Here, a value that provides a high gain may be set as the threshold value. Also, the gain in the interference wave direction can be reduced to the maximum. This is explained in FIG. 3 because the gain in the interference wave direction monotonously decreases as the number of incoming signals increases.

  That is, by using the weight selection method of the present embodiment, the beam pattern formation that receives the desired wave with high gain and suppresses the interference wave is insufficiently calibrated, and the result of setting the number of incoming signals is Even if there is an error, it can be realized with high accuracy.

  As described above, in the present embodiment, the weight setting unit 105 performs direction vector correction, weight calculation, and gain calculation in the desired wave direction under the condition of the number of consecutive different incoming signals. Then, the number of incoming signals is selected using only the gain in the desired wave direction, and the weight corresponding to the selected number of incoming signals is selected. Then, using this weight to synthesize the received signal of adaptive array antenna apparatus 100 receives the desired wave with a high gain and suppresses the interference wave, so that the desired wave having a large amplitude without interference. A signal can be obtained.

  In this embodiment, the weight setting means 105 calculates weights in parallel under different conditions of the number of incoming signals. As a result, the weight can be calculated at a higher speed than in the case where the weight is calculated in order while changing the number of incoming signals, and the real-time property is improved. In this embodiment, the weight is selected with a gain only in the desired wave direction. Therefore, the gain in the direction in which the incoming wave exists can be reliably evaluated under conditions other than the condition where the number of incoming signals is zero, and can be applied even when the estimation of the number of incoming signals is difficult. When the number of incoming signals is 0, since only noise is included in the received signal, it can be easily determined.

  As described above, according to the present embodiment, even when it is difficult to estimate the number of incoming signals, weights can be calculated under different conditions of the number of incoming signals, and weights can be selected from them. Setting (realization of a beam pattern for suppressing interference waves while maintaining a high gain in the desired wave direction) can be performed.

  Further, according to the present embodiment, it is possible to select a weight (beam pattern) capable of suppressing the interference wave while maintaining the gain in the desired wave direction to be equal to or higher than the threshold gain.

(2) Second Embodiment Hereinafter, a second embodiment will be described in detail with reference to the drawings. FIG. 4 shows a configuration diagram of the weight setting means 400 according to the second embodiment. Weight setting means 400 includes arrival signal number setting means 401, direction vector correction means 402, weight calculation means 403, desired wave direction gain calculation means 404, weight selection means 405, and arrival signal number change means 406. Composed. By configuring the weight setting unit 400 in this way, it is possible to realize the low-cost weight setting unit 400, although the calculation speed is reduced as compared with the first embodiment. This will be described in detail below.

  Hereinafter, the operation of this embodiment will be described. The operations of the direction vector correction unit 402, the weight calculation unit 403, and the desired wave direction gain calculation unit 404 are the same as those in the first embodiment, and thus detailed description thereof is omitted.

  First, the arrival signal number setting means 401 sets the number of arrival signals used by the direction vector correction means 402. Here, an arbitrary number of incoming signals may be set. For example, the arrival signal number estimation result of the adaptive array antenna apparatus can be used.

  Then, using the set number of incoming signals, correction of the direction vector in the desired wave direction, calculation of the weight, and calculation of the gain in the desired wave direction are performed. Then, the processing method is changed as follows depending on whether the gain in the desired wave direction is larger or smaller than the threshold.

  First, the case where the gain value in the desired wave direction is larger than the threshold will be described. In this case, high gain reception of the desired wave is possible, but interference wave suppression may be insufficient. Therefore, the number of incoming signals is increased by one by the incoming signal number changing means 406. Similarly, direction vector correction, weight calculation, and gain calculation in the desired wave direction are performed. This calculation is repeated until the gain in the desired wave direction becomes smaller than the threshold value.

  By calculating in this way, it is possible to select a weight having a desired wave direction gain larger than the threshold and having the maximum interference wave suppression effect. Here, the weight selection criterion is performed based on the knowledge shown in FIG. 3 as described in the first embodiment.

  Next, the case where the gain value in the desired wave direction is smaller than the threshold value will be described. In this case, high gain reception of the desired wave is insufficient. Accordingly, the number of incoming signals is decreased by one by the incoming signal number changing means 406. Similarly, direction vector correction, weight calculation, and gain calculation in the desired wave direction are performed. This calculation is repeated until the gain in the desired wave direction becomes larger than the threshold value.

  By calculating in this way, it is possible to select a weight having a desired wave direction gain larger than the threshold and having the maximum interference wave suppression effect. Here, the weight selection criterion is performed based on the knowledge shown in FIG. 3 as described in the first embodiment.

  As described above, in the second embodiment, the optimum weight is set by sequentially correcting the direction vector, calculating the weight, and calculating the gain in the desired wave direction under different conditions of the number of incoming signals. It becomes possible to do. In addition, since the operations are performed in order, the hardware configuration can be reduced, and the cost of the apparatus can be reduced.

(3) Third Embodiment Hereinafter, a third embodiment will be described in detail. The present embodiment relates to a threshold value setting method used as a weight selection criterion. The threshold value is a value obtained by subtracting a predetermined value from the maximum gain that can be realized by the adaptive array antenna apparatus 100. Hereinafter, the effect of setting the threshold value in this way will be described.

  In the present embodiment, a predetermined value is set as the degradation amount for performing interference suppression, based on the maximum gain when interference wave suppression is not performed. As a result, the amount of gain degradation in the desired wave direction can be kept within a predetermined value.

  For example, the maximum gain that can be realized by the array antenna 101 can be obtained by the frequency of the incoming wave, the type and arrangement method of each antenna of the array antenna 101. Actually, since the calibration is insufficient, the maximum gain that can be strictly realized by the actual adaptive array antenna apparatus 100 is not obtained. However, the calculation is performed using data having an error. For example, when 3 dB is set as the predetermined value, the maximum interference wave suppression effect can be realized in a state where the gain deterioration amount in the desired wave direction is 3 dB at the maximum.

  As described above, in the present embodiment, the threshold value is set to a value obtained by subtracting a predetermined value from the maximum gain that can be realized by adaptive array antenna apparatus 100, whereby the amount of gain degradation in the desired wave direction is set to a predetermined value. It can be within the value.

(4) Fourth Embodiment Hereinafter, a fourth embodiment will be described in detail. The present embodiment relates to a threshold value setting method used as a weight selection criterion. The threshold is set by the absolute gain of adaptive array antenna apparatus 100 corresponding to the minimum power required for the incoming signal power output from received signal output means 106. Hereinafter, the effect of setting the threshold value in this way will be described.

  In the present embodiment, the minimum gain necessary for receiving the desired wave is set as a threshold value. As described in FIG. 3, as the gain in the desired wave direction decreases, the gain in the interference wave direction also decreases. As a result, by setting the threshold as in the present embodiment, it is possible to obtain the maximum interference wave suppression effect while maintaining the minimum required wave reception gain.

  As described above, in the present embodiment, the threshold is set by the absolute gain of adaptive array antenna apparatus 100 corresponding to the minimum required power for the incoming signal power output from received signal output means 106. It is possible to obtain the maximum interference wave suppression effect while maintaining the minimum desired wave reception gain. This embodiment is effective when it is desired to suppress interference waves to the maximum.

(5) Fifth Embodiment Hereinafter, a fifth embodiment will be described in detail. Although the present embodiment relates to a method for calculating the gain in the desired wave direction, the gain is calculated using an omnidirectional composite beam pattern calculated from the coordinates of the array antenna 101, the beam pattern of each antenna of the array antenna 101, and the weight. And calculating the directivity gain.

  When the weight selected by the weight selection means 205 or 405, the coordinates of the array antenna 101, and the beam pattern of each antenna of the array antenna 101 are used, the beam pattern of the adaptive array antenna apparatus 100 is calculated using the array directivity synthesis theory. I can do it. The coordinates of each element and the beam pattern of each antenna used here include errors because they are not sufficiently calibrated, and are calculated using these.

  Once the beam pattern is calculated, the directivity gain can be calculated. The directivity gain is calculated by a commonly used calculation formula, and is calculated by the ratio of the value of the beam pattern in the desired wave direction and the average value of the beam patterns in all directions.

  By calculating the gain in this way, the gain in the desired wave direction can be calculated with relatively high accuracy. In such a method, the element spacing of each element of the antenna is extremely narrow and the elements of the antenna are very close to each other, or the element spacing of each element of the antenna is extremely wide. This is effective because the gain can be correctly evaluated when a high-gain beam pattern is generated.

(6) Sixth Embodiment Hereinafter, a sixth embodiment will be described in detail. In the present embodiment, the maximum gain and the gain in the desired wave direction when the threshold value is set to a value obtained by subtracting a predetermined value from the maximum gain that can be realized by adaptive array antenna apparatus 100. Regarding the calculation method. Here, the maximum realizable gain is the power when the electric field of each antenna calculated from the beam pattern and weight of each antenna of the array antenna 101 is combined in phase in the desired wave direction, and the gain in the desired wave direction is The electric power of each antenna of the array antenna 101, which is calculated from the beam pattern and weight of each antenna, is used as the power for complex synthesis in the desired wave direction. This will be described in detail below.

The composite beam pattern in the desired wave direction can be calculated by complex synthesis of the electric field as shown in the following equation (13).

In Expression (13), this is a condition when the electric field when the radiated electric field from each antenna element is combined in phase in the desired direction has the maximum gain. Therefore, the maximum gain can be obtained by equation (14).

  In the present embodiment, the maximum gain is calculated by Expression (14), and the gain in the desired wave direction is calculated by Expression (13). Accordingly, integration of the entire space necessary for calculating the directivity gain is unnecessary, and gain evaluation can be performed at high speed.

  Here, equation (14) has different values when different weights are used. Therefore, there is a degree of freedom in the method for setting the maximum gain.

  When it is desired to keep the gain in the desired wave direction high, the maximum value may be selected from the maximum gains calculated by Expression (14).

  When emphasizing suppression of interference waves, the minimum value among the maximum gains calculated by Expression (14) may be selected.

  Further, when it is desired to balance the gain in the desired wave direction and the interference wave suppression, the average value of the maximum gains calculated by the equation (14) may be used.

  As described above, in the present embodiment, the maximum gain that can be realized is the case where the electric field of each antenna calculated from the beam pattern and the weight of each antenna of array antenna 101 is combined in phase in the desired wave direction. And the gain in the desired wave direction is the power when the electric field of each antenna calculated from the beam pattern and weight of each antenna of the array antenna 101 is complex-combined in the desired wave direction. The amount can be greatly reduced, contributing to the improvement of real-time performance. In addition, it is possible to realize a cost reduction associated with hardware reduction and a reduction in power consumption due to a reduction in calculation amount. By simply calculating the gain value as in the present embodiment, the gain calculation accuracy deteriorates, but the calculation time can be greatly shortened.

(7) Seventh Embodiment Hereinafter, a seventh embodiment will be described in detail with reference to the drawings. FIG. 5 is a configuration diagram of the adaptive array antenna apparatus 500 according to the present embodiment, and is characterized by further having an incoming signal number comparison means 507. In this arrival signal number comparison means 507, the number of arrival signals set by the arrival signal number setting means 502 is compared with the number of arrival signals corresponding to the weight set by the weight setting means 505. The number of incoming signals corresponding to the weight set in step 505 is selected, and information on the selected number of incoming signals is input to the arrival direction setting means 503. With this configuration, the arrival direction setting accuracy is improved, and as a result, high gain reception of the desired wave and suppression of the interference wave can be realized with higher accuracy. This will be described in detail below.

  In the weight setting means 505, the calculation is performed by changing the number of incoming signals, and the number of incoming signals having a desired beam pattern is calculated. Therefore, this calculation can be considered as one method for estimating the number of incoming signals.

  When the set value in the arrival signal number setting means 502 is smaller than the actual arrival wave, the arrival direction setting means 503 cannot set the directions of all the arrival waves. On the other hand, if there are more than the actual arrival waves, the arrival direction setting means 503 sets the direction of the false arrival waves. In addition, if there is an error in the number of incoming signals, the error in the direction of arrival may increase.

  Accordingly, by performing the arrival direction estimation using the number of arrival signals selected by the weight calculation means 505, the arrival wave that has not been set can be changed to a desired wave, the false arrival wave can be eliminated, or the arrival direction estimation accuracy can be reduced. It is possible to improve.

  As a result, there is an effect of increasing the selection range of the desired wave by making the incoming wave that has not been set the desired wave. By eliminating false incoming waves, there is an effect of eliminating useless computation for calculating the false direction as a desired wave. By improving the arrival direction estimation accuracy, it becomes possible to set a more accurate direction vector with respect to the setting of the direction vector, and as a result, more accurate beam pattern formation is realized.

  As described above, the adaptive array antenna apparatus 500 according to the present embodiment further includes the arrival signal number comparison means 507, and can set the arrival direction under the condition of the number of arrival signals selected by the weight setting means 505. As a result, it is possible to increase the number of incoming waves set with desired waves, reduce useless computations, and realize more accurate beam pattern formation.

  Thus, according to the present embodiment, it is possible to estimate an arrival direction that cannot be estimated when there is a large error in the estimated number of incoming signals. In addition, the arrival direction estimation accuracy can be improved.

(8) Eighth Embodiment Hereinafter, an eighth embodiment will be described in detail with reference to the drawings. FIG. 6 is a configuration diagram of an adaptive array antenna apparatus 600 according to this embodiment. Propagation state monitoring means 607 is provided, and when the propagation state is constant for a predetermined time, the weight before the predetermined time is set by the weight setting means 605. As a result, useless calculations are omitted, contributing to low power consumption. This will be described in detail below.

  The propagation state monitoring unit 607 compares the arrival signal number setting value and the arrival direction setting value for a predetermined time before the current arrival signal number setting value and the arrival direction setting value.

  When the value is different from the predetermined time before and at present, the propagation environment of the incoming wave has changed, so that the weight setting means 605 calculates the weight as described above.

  If the value is the same before and after the predetermined time, it can be said that there is no change in the propagation environment of the incoming wave. Therefore, it is possible to obtain sufficiently desired characteristics with the beam pattern before a predetermined time. As a result, it is not necessary to perform a plurality of calculations again for setting the weight. In this case, the weight before the predetermined time is used as it is, and this is set again.

  As described above, in this embodiment, when the propagation state does not change, the same weight as that before a predetermined time is set again, thereby reducing the amount of calculation in the weight setting means 605 and reducing the power consumption. It becomes possible to contribute to. In particular, this is effective when the propagation state is stable or when the adaptive array antenna apparatus 600 is realized by a small terminal.

  Although the number of incoming signals is compared with the direction of arrival, one of these may be used, or both may be used.

(9) Other Embodiments In the above description, the configuration of the weight setting means 105, 505 and 605 is calculated in parallel with different numbers of incoming signals, or is calculated in order while changing the number of incoming signals. There were two ways. Here, as an intermediate configuration between these, a configuration may be used in which calculation is performed in parallel with a small number of different incoming signals, and this is repeatedly calculated. In this case, it is possible to realize a balanced configuration of downsizing the hardware and increasing the calculation speed.

  In the above-described embodiment, as a calculation hardware in each means, a general-purpose CPU used in a personal computer, a device called DSP (Digital Signal Processor) capable of high-speed calculation, or an FPGA (Field Primitive Gate). It is possible to use a programmable LSI called (Array), and a combination thereof may be realized.

  In the above-described embodiment, it is effective to assign calculation hardware independently to the calculation of each part in order to set the weight at high speed and obtain a desired wave reception signal. In this case, for example, in the repetitive calculation as shown in FIG. 4, it is effective to perform calculation one after another while changing the value of the number of incoming signals as shown in FIG. In this case, useless calculation occurs for the weight setting, but it is effective when high-speed calculation is required.

Further, in the above-described embodiment, the noise subspace V _N is calculated by Expression (10). Here, the noise subspace V _N is part of the composed V eigenvectors v _i. Since V is a constant matrix regardless of the number of incoming signals, it is not necessary to recalculate once it has been calculated. Therefore, when the number of incoming signals is changed and the noise subspace V _N is set, data corresponding to the number of incoming signals may be assigned from among Vs calculated in advance. By doing so, it is possible to reduce the processing time and power consumption associated with the omission of computation.

  The above-described embodiment relates to an adaptive array antenna apparatus that receives only a desired wave from a plurality of incoming waves, and can be used for communication such as mobile communication, fixed communication, and satellite communication. Further, the present invention can be applied to an adaptive array antenna device for radio wave monitoring business such as radio wave control. In addition, in the on-vehicle collision prevention radar, it is also possible to apply the case where the reflected wave of the radar of the own vehicle and the radar wave from another vehicle are separated. The application technical field of the above embodiment is not limited and can be widely applied.

  Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the components without departing from the scope of the invention in the implementation stage. In addition, various inventions can be formed by appropriately combining a plurality of components disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined.

The block diagram for demonstrating the structure of the adaptive array antenna apparatus by the 1st Embodiment of this invention. The block diagram for demonstrating the structure of the weight setting means of the adaptive array antenna apparatus. The graph for demonstrating the selection principle used for the weight selection means of the weight setting means. The block diagram for demonstrating the structure of the weight setting means by the 2nd Embodiment of this invention. The block diagram for demonstrating the structure of the adaptive array antenna apparatus by the 7th Embodiment of this invention. The block diagram for demonstrating the structure of the adaptive array antenna apparatus by the 8th Embodiment of this invention. Explanatory drawing of the calculation method in the weight setting means in 2nd Embodiment.

Explanation of symbols

100, 500, 600 Adaptive array antenna apparatus 101, 501, 601 Array antenna 102, 201, 401, 502, 602 Arrival signal number setting means 103, 503, 603 Arrival direction setting means 104, 504, 604 Desired wave direction setting means 105 , 400, 505, 605 Weight setting means 106, 506, 606 Received signal output means 202, 402 Direction vector correction means 203, 403 Weight calculation means 204, 404 Gain calculation means 205, 405 Weight selection means 406 Signal number change means 507 Arrival Signal number comparison means 607 Propagation state monitoring means

Claims (12)

An array antenna for receiving incoming waves,
An arrival signal number setting means for estimating and setting the number of arrival signals of the arrival wave based on the reception signals received by the array antenna;
Direction-of-arrival setting means for estimating and setting the direction of arrival of the incoming wave based on at least the received signal;
Desired wave direction setting means for selecting and setting the arrival direction of the desired arrival wave as the desired wave direction from the set arrival directions of the arrival waves;
A plurality of correction direction vectors are generated by correcting the direction vector of the desired wave direction in the array antenna using a plurality of different numbers of incoming signals, and a plurality of weights are generated using the plurality of correction direction vectors. And a weight setting means for selecting and setting a desired weight from the plurality of weights,
An adaptive array comprising: a reception signal output unit configured to synthesize and output the reception signal using the reception signal received by the array antenna and the weight set by the weight setting unit. Antenna device. The weight setting means includes
Using the plurality of calculated weights, a gain in the desired wave direction in the array antenna is calculated for each number of incoming signals, and a predetermined threshold value among the calculated gains in the desired wave direction is calculated. The maximum number of incoming signals is selected from the number of incoming signals corresponding to a large gain in the desired wave direction, and the weight corresponding to the selected number of incoming signals is set. The adaptive array antenna apparatus according to Item 1. The weight setting means includes
A plurality of weight setting arrival signal number setting means for setting different numbers of the different arrival signals so as to be continuous;
The plurality of correction direction vectors are generated by correcting the direction vector in the desired wave direction in the array antenna using the number of arrival signals set by the plurality of weight setting arrival signal number setting means. A plurality of direction vector correction means;
A plurality of weight calculating means for calculating each of the plurality of weights using the plurality of correction direction vectors generated by the plurality of direction vector correcting means;
A plurality of gain calculating means for calculating the gain of the desired wave direction in the array antenna for each number of incoming signals, using the plurality of weights calculated by the plurality of weight calculating means;
Weight selection means for selecting and setting a desired weight from among the plurality of weights using the gain in the desired wave direction in the array antenna calculated for each number of incoming signals by the plurality of gain calculation means; The adaptive array antenna apparatus according to claim 1, further comprising: The weight setting means includes
Weight setting arrival signal number setting means for setting the number of arrival signals;
Direction vector correction means for generating the correction direction vector by correcting the direction vector of the desired wave direction in the array antenna using the number of arrival signals set by the weight setting arrival signal number setting means. ,
Weight calculation means for calculating the weight using the correction direction vector generated by the direction vector correction means;
Gain calculating means for calculating a gain in the desired wave direction in the array antenna using the weight calculated by the weight calculating means;
When the gain in the desired wave direction calculated by the gain calculation means is larger than a predetermined threshold, 1 is added to the number of incoming signals set in the weight setting arrival signal number setting means, When the gain in the desired wave direction is smaller than the threshold, the number of incoming signal changing means for subtracting 1 from the number of incoming signals set in the weight setting incoming signal number setting means;
Weight selection means for selecting a desired weight from among the plurality of weights sequentially calculated using the gain in the desired wave direction in the array antenna that is sequentially calculated for each number of incoming signals by the gain calculation means; The adaptive array antenna apparatus according to claim 1, further comprising: The weight setting incoming signal number setting means includes:
The adaptive array antenna apparatus according to claim 4, wherein the number of incoming signals estimated and set by the number of incoming signal setting means is set. The weight setting means includes
The adaptive array antenna apparatus according to claim 2, wherein a value obtained by subtracting a predetermined value from a maximum gain in the array antenna is set as the threshold value. The weight setting means includes
The adaptive array antenna apparatus according to claim 2, wherein a gain corresponding to an amount of power required for an output signal output from the reception signal output means is set as the threshold value. The weight setting means includes
Based on the coordinates of the array antenna, the beam pattern of each antenna forming the array antenna, and the weight, an omnidirectional composite beam pattern is calculated, and the desired wave direction is calculated using the omnidirectional composite beam pattern. The adaptive array antenna apparatus according to claim 2, wherein the gain is calculated as a directivity gain. The weight setting means includes
By calculating the electric field of each antenna based on the beam pattern of each antenna forming the array antenna and the weight, and combining the calculated electric field of each antenna in the desired wave direction, 7. The gain in the desired wave direction in the array antenna is calculated by calculating the maximum gain in the array antenna and complex-combining the electric fields of the antennas in the desired wave direction. Adaptive array antenna device. The number of incoming signals set by the number of incoming signal setting means is compared with the number of incoming signals corresponding to the weight set by the weight setting means, and if they do not match, the weight setting means The apparatus further comprises: an arrival signal number comparison unit that causes the arrival direction setting unit to perform estimation and setting of the arrival direction using the number of arrival signals corresponding to the weight set by (1). Adaptive array antenna device. The number of incoming signals and the direction of arrival set in a predetermined time before in the number of incoming signals setting means and the direction of arrival setting means are compared with the number of incoming signals and the direction of arrival currently set, The adaptive array antenna apparatus according to claim 1, further comprising: a propagation state monitoring unit that resets the weight set before the predetermined time in the weight setting unit when at least one of them matches. . Estimating and setting the number of arriving signals based on the received signals received by the array antenna; and
Estimating and setting the direction of arrival of the incoming wave based at least on the received signal;
Selecting and setting a desired arrival direction as a desired direction from the set arrival directions of the arrival waves; and
A plurality of correction direction vectors are generated by correcting the direction vector of the desired wave direction in the array antenna using a plurality of different numbers of incoming signals, and a plurality of weights are generated using the plurality of correction direction vectors. Respectively, and a step of selecting and setting a desired weight from the plurality of weights;
A received signal processing method for an adaptive array antenna device, comprising: combining the received signal using the received signal received by the array antenna and the set weight and outputting the synthesized signal. .

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