JP4901643B2 - Adaptive array antenna apparatus and program - Google Patents

Description

  The present invention relates to an adaptive array antenna apparatus and a program for an interference wave suppression technique among adaptive array antenna techniques.

  In the field of radio wave monitoring and wireless communication, there is a demand for a technique for separating a plurality of incoming signals that have been received due to interference into original signals. The adaptive array antenna multiplies the reception signals of the plurality of antennas by weights, and then adds the plurality of reception signals multiplied by the weights. When this weight is appropriately set, a specific incoming signal is synthesized with the same phase, and the remaining incoming signals are synthesized so as to cancel each other. As a result, only a specific incoming signal is obtained from the interfering incoming signals. That is, the adaptive array antenna can be used as signal separation means.

  In adaptive array antennas, setting weights is important. When the power difference between interfering incoming signals is sufficiently large, the eigenvector beamspace method can calculate weights that can separate the signals. Then, the separated signal is output. As the power difference at this time, the power of either the desired signal or the undesired (interference) signal may be large. That is, it is sufficient if the power difference between signals is large.

  However, when the power difference between the signals is small, the eigenvector beamspace method has a problem that the signals cannot be separated.

As a solution to this problem, a technique for controlling the power of a transmitter that transmits a signal is known (see, for example, Patent Document 1).
JP 2002-64323 A

  However, since the conventional technique requires control of a transmitter that transmits a signal, communication is required between the transmitter and the adaptive array antenna apparatus. Therefore, there is a problem that only the incoming signal of the transmitter that can communicate can be controlled. Therefore, this technology has a narrow scope of application.

  As described above, in the conventional adaptive array antenna apparatus, only an incoming signal that can be communicated can be controlled, and there is a problem that the application range is narrow. In addition, the adaptive array antenna apparatus requires a transmitter for performing communication, and thus there is a problem that costs increase.

  The present invention has been made in consideration of the above-described circumstances, and an object thereof is to provide an adaptive array antenna apparatus and program capable of separating a signal from an arbitrary incoming signal.

In order to solve the above-described problems, an adaptive array antenna apparatus according to the present invention includes an array antenna including a plurality of antenna elements that receive a plurality of incoming signals, direction estimation means for estimating the direction of arrival for each of the incoming signals, and the arrival Power estimation means for estimating power for each signal; and the array antenna is divided into subarrays having a larger number of incoming signals composed of a plurality of antenna elements, and the beam directions of the plurality of subarrays are estimated by the power estimation means. When there are a plurality of incoming signals having the largest power among all the plurality of powers or a plurality of incoming signals having the largest power among all the plurality of powers estimated by the power estimation means, one of the incoming signal, and toward Ke in the arrival direction is the same in all the sub-arrays which are estimated by the direction estimation means, said array An acquisition unit configured to acquire a plurality of received signals at antenna by comparing calculated eigenvectors by applying the eigenvector beam space method to the plurality of received signals, comprising a separation means for separating said plurality of incoming signals The signal separation is possible even when there is no power difference between the plurality of incoming signals .

An adaptive array antenna apparatus according to the present invention includes an array antenna including a plurality of antenna elements that can receive a plurality of incoming signals and change a beam direction, direction estimation means for estimating an arrival direction for each incoming signal, and the incoming signal. Power estimation means for estimating the power for each, and an incoming signal having the largest power among all of the plurality of powers estimated by the power estimation means, or all of the plurality of powers estimated by the power estimation means When there are a plurality of incoming signals having the largest power , the beam is directed to the same arrival direction of all the antenna elements estimated by the direction estimating means of one of the incoming signals. Control means for controlling a plurality of antenna elements; and receiving the plurality of incoming signals when the control means controls the plurality of antenna elements. By comparing calculated eigenvectors by applying the eigenvector beamspace method No., separating means for separating said plurality of incoming signal, comprising the, also signal separation when there is no power difference of the plurality of incoming signals It is possible to make it possible .

  According to the adaptive array antenna apparatus and program of the present invention, a signal can be separated from an arbitrary incoming signal.

Hereinafter, an adaptive array antenna apparatus and a program according to embodiments of the present invention will be described in detail with reference to the drawings. Note that, in the following embodiments, the same numbered portions are assumed to perform the same operation, and repeated description is omitted.
(First embodiment)
The adaptive array antenna apparatus of this embodiment will be described with reference to FIG.
The adaptive array antenna apparatus of this embodiment includes an array antenna unit 106, a digital signal processing circuit 110, a signal separation unit 111, and a signal selection unit 112.

  The array antenna unit 106 receives a plurality of incoming signals by the plurality of antenna elements 101, converts each received signal into a digital signal, and converts the received signal from each antenna element 101 into a digital signal processing circuit 110. To pass. That is, the same number of digital signals as the number of antenna elements 101 are input to the digital signal processing circuit 110.

  The digital signal processing circuit 110 estimates the arrival direction of the incoming signal, the number of incoming signals, and the power of the incoming signal based on the plurality of digital signals from the array antenna unit 106, and emits a beam in the direction of the incoming signal having higher power. A plurality of received signals are obtained, and these received signals are passed to the signal separation unit 111.

  The signal separation unit 111 applies the eigenvector beam space method to the plurality of reception signals from the digital signal processing circuit 110 to separate the reception signals, and passes the separated plurality of reception signals to the signal selection unit 112. Details of the signal separation unit 111 will be described later with reference to FIG.

  The signal selection unit 112 selects an output including a desired signal from the plurality of reception signals separated by the signal separation unit 111. Details of the signal selection unit 112 will be described after the signal separation unit 111 described later with reference to FIG.

  The array antenna unit 106 includes a plurality of antenna elements 101, a gain amplifier 102 that amplifies a signal received by each antenna element 101, a filter 103 that filters a frequency band of the amplified signal to a desired band, A frequency conversion unit 104 that converts a frequency and an analog-digital converter (A / D converter) 105 that converts an analog signal into a digital signal are included. The antenna element 101 can receive an incoming signal. There is no restriction on the type of antenna element. An existing antenna element may be used. For example, when it is desired to receive an incoming signal from a wide angle range, an antenna having a wide beam width such as a microstrip antenna or a monopole antenna may be used. Conversely, when it is desired to receive only a narrow range of incoming signals, an antenna having a narrow beam width such as a horn antenna or a Yagi-Uda antenna may be used. In this way, it is only necessary to use different antennas according to demand.

The digital signal processing circuit 110 includes an arrival direction / arrival signal number estimation unit 107, an arrival signal power estimation unit 108, and a beam reception unit 109.
The arrival direction / arrival signal number estimation unit 107 estimates the arrival direction and the number of arrival signals of incoming signals incident on a plurality of antenna elements 101 (hereinafter referred to as array antennas) of the array antenna unit 106. There are no restrictions on the arrival direction estimation algorithm and the arrival signal number estimation algorithm. Existing algorithms may be used. In the arrival direction estimation algorithm, for example, when it is desired to reduce the amount of calculation of the algorithm, the beam former method may be used. If you want to accurately estimate incoming signals at close angles, you can use the MUSIC method or ESPRIT method. Thus, the algorithm used according to the situation of the incoming signal may be properly used.

  An existing algorithm may be used as the arrival signal number estimation algorithm. For example, the AIC method or MDL method may be used. If the received data is input to the evaluation function of the AIC method or the MDL method, the number of incoming signals is estimated. These methods can be obtained without setting a threshold value or the like in advance. Alternatively, the eigenvalue is obtained by calculating a correlation matrix from the received signal of the antenna. This eigenvalue is obtained as many as the number of antenna elements. A method may be used in which these eigenvalues are compared with threshold values, and the number of eigenvalues having a magnitude greater than or equal to the threshold value is used as the number of incoming signals. In this method, it is necessary to determine a threshold value in advance, but it is not necessary to calculate an evaluation function. Use it according to the situation.

  The incoming signal power estimation unit 108 estimates the power of the incoming signal incident on the array antenna. There are no restrictions on the incoming signal power estimation algorithm. Existing algorithms may be used. For example, the beamformer method, the MUSIC method, and the ESPRIT method may be used as in the arrival direction / arrival signal number estimation unit 107. For the purpose of reducing the amount of calculation, the same algorithm as the arrival direction estimation algorithm may be used. Conversely, an algorithm different from the arrival direction estimation algorithm may be used for the purpose of improving power estimation accuracy. In this way, the algorithm to be used may be properly used depending on the situation.

  The beam receiving unit 109 obtains a plurality of received signals by directing the beam in the direction of an incoming signal having high power. The beam receiving unit 109 receives a plurality of received signals received by the array antenna so that an incoming signal having a higher power is received by a main beam having a higher gain and an incoming signal having a lower power is received by a side lobe having a lower gain. And direct the beam in the direction of the incoming signal. In this embodiment, “directing the beam” does not actually adjust the beam by moving the direction of the array antenna, but receives each of the plurality of antenna elements 101 while maintaining the initial direction of the array antenna. By multiplying a signal by a weight and adding a plurality of received signals multiplied by the weight, it is shown that the same effect can be obtained as when the beam is directed by actually moving the direction of the array antenna. Thus, in the data after reception after directing the beam, the power difference between the incoming signals is larger.

  Note that the direction of the beam directed by the beam receiving unit 109 is the direction of the incoming signal having a large power. The signal in this direction may be a desired signal that is finally desired or an interference signal that is not finally desired because the power difference between the incoming signals may be increased.

  For example, as shown in FIG. 2, the beam receiving unit 109 forms one group (hereinafter referred to as a subarray) with three antenna elements 101 installed adjacent to each other, and transmits a beam in the direction of an incoming signal. To get the received signal. In the subarray 201, the beam receiving unit 109 performs a weighted sum on the digital signal obtained from the antenna element 101 included in the subarray. That is, the array antenna is divided into a plurality of subarrays 201, and each subarray 201 creates a beam 202 and directs these beams 202 to the incoming signal with the higher power. A plurality of received data is obtained using these beams 202. As a result, a plurality of beam reception signals are obtained. Hereinafter, a signal obtained from the subarray 201 by the beam receiving unit 109 is referred to as a beam reception signal.

  Note that the number of subarrays included in the array antenna unit 106 needs to be larger than the number of incoming signals. Therefore, the beam receiving unit 109 calculates the weighted sum after setting the number of subarrays to be larger than this number according to the number of arrival signals obtained by the arrival direction / arrival signal number estimation unit 107. Further, the beam receiving unit 109 may be performed by a method other than the method shown in FIG. In the example of FIG. 2, the beam reception unit 109 adjusts the beam direction and obtains a plurality of beam reception signals from each subarray 201.

Next, the signal separation unit 111 in FIG. 1 will be described with reference to FIG.
The signal separation unit 111 applies the eigenvector beam space method to the plurality of beam reception signals and outputs the separated signals. As shown in FIG. 3, the signal separation unit 111 includes a correlation matrix calculation unit 301, an eigenvector calculation unit 302, and an eigenvector beam space output calculation unit 303.

Correlation matrix calculation section 301 calculates a correlation matrix using a vectorized reception signal having a plurality of beam reception signals as elements. The description will be given below using mathematical expressions.
The vectorized received signal is expressed by the following equation (1).

Y (t) = [y ₁ (t), y ₂ (t),..., Y _M (t)] ^T equation (1)
Here, y _m (t) (m = 1,..., M; M is the number of subarrays) is the mth beam reception signal, and t means time. T is a symbol representing transposition. Correlation matrix calculation section 301 calculates correlation matrix R by equation (2) using Y (t) of equation (1).

R = E [Y (t) Y (t) ^H ] Formula (2)
Here, E [] means expected value calculation. H is a symbol representing a complex conjugate transpose. Specifically, the time average calculation of the following equation (3) is performed.

Here, Ts is the number of samples used for averaging. The correlation matrix calculation unit 301 calculates a correlation matrix from Expression (3).

  The eigenvector calculation unit 302 calculates the eigenvector of the correlation matrix R calculated by Expression (3). The eigenvector calculation unit 302 calculates eigenvectors and eigenvalues using an existing matrix calculation algorithm.

The eigenvector beam space output calculation unit 303 uses the eigenvalue obtained by the eigenvector calculation unit 302 as a weight to perform a product-sum operation on the beam reception signal. The description will be given below using mathematical expressions.
Eigenvector Beamspace output calculation unit 303, the eigenvectors obtained by the eigenvector calculator _{302 e m (m = 1,} ···, M) and. Here, eigenvectors corresponding to m-th eigenvalue rearranged in descending order are e _m. Eigenvector Beamspace output calculation unit 303, a beam reception signal Y (t) and using _{e m,} m-th eigenvector beam output Zm (t) is calculated by equation (4).

^{_{Zm (t) = e m H}} Y (t) (4)
M types of eigenvector beamspace outputs are calculated using equation (4). The signal separation unit 111 of the present embodiment is configured by the three device parts described above, but may be configured by a procedure by another device part that can perform the same calculation as Expression (4).

Next, details of the signal selection unit 112 will be described.
The signal selection unit 112 selects an output including a desired signal from a plurality of eigenvector beam space outputs. As a selection criterion for a desired signal, an arrival direction, a modulation method, or the like may be used. Hereinafter, a case where the arrival direction and the modulation scheme are used will be described.

When the arrival direction is selected as a selection criterion, the beam pattern is calculated using the weight e _m ^H used for obtaining the m-th eigenvector beam output Zm (t) as the weight of the array antenna. The direction of the incoming signal included in the m-th eigenvector beam output Zm (t) is estimated from the maximum direction of the obtained beam pattern. The output Zm (t) corresponding to the desired direction of arrival may be selected using the direction of arrival estimated in this way.

  When the modulation method is selected as a selection criterion, the modulation method of the mth eigenvector beam output Zm (t) is estimated. Thereby, the modulation scheme of the eigenvector beam output Zm (t) is estimated. The output Zm (t) corresponding to the desired modulation method may be selected using the modulation method thus estimated.

Next, the effectiveness of the adaptive array antenna apparatus of this embodiment will be described with reference to the simulation results of FIG.
The horizontal axis of FIG. 4 represents the power ratio (dB) between the incoming signal A and the incoming signal B. The vertical axis represents the power ratio (dB) between the incoming signal A and the incoming signal B after being processed by the adaptive array antenna.

  A positive value on the horizontal axis represents a range in which the incoming signal A is larger than the incoming signal B, and a negative value on the horizontal axis represents a range in which the incoming signal A is smaller than the incoming signal B. Similarly, on the vertical axis, a positive value represents a range in which the incoming signal A is larger than the incoming signal B, and a negative value represents a range in which the incoming signal A is smaller than the incoming signal B.

  The solid line in FIG. 4 represents the result of the conventional eigenvector beamspace method. The broken line in FIG. 4 shows the result of processing by the adaptive array antenna apparatus of this embodiment. The results are obtained when the arrival direction / arrival signal number estimation unit 107, the arrival signal power estimation unit 108, the beam reception unit 109, and the signal selection unit 112 are correctly estimated without error.

  First, the result of the conventional eigenvector beam space method will be described. When the power ratio between the incoming signal A and the incoming signal B is large, the power ratio between the incoming signal A and the incoming signal B also increases at the output. However, as the power ratio between the incoming signal A and the incoming signal B decreases, the power ratio between the incoming signal A and the incoming signal B at the output decreases. That is, the signal separation performance is degraded. In particular, when the power ratio between the incoming signal A and the incoming signal B becomes 0 dB, the output is 0 dB and cannot be separated at all. The adaptive array antenna apparatus of this embodiment enables separation even in this case.

  Next, a result obtained by processing with the adaptive array antenna of the present embodiment will be described. When the power ratio between the incoming signal A and the incoming signal B is large, the power ratio between the incoming signal A and the incoming signal B also increases at the output. This performance is equivalent to the conventional eigenvector beamspace method. Further, when the power ratio between the incoming signal A and the incoming signal B decreases, the power ratio between the incoming signal A and the incoming signal B at the output gradually decreases, but becomes a larger value than the conventional value. Yes. In particular, even when the power ratio between the incoming signal A and the incoming signal B is 0 dB, the output is 5 dB or more. That is, according to the adaptive array antenna apparatus of the present embodiment, it is possible to separate the incoming signal A and the incoming signal B that could not be separated at all in the prior art.

  According to the first embodiment described above, the adaptive array antenna apparatus of the present embodiment interferes with the arrival direction / arrival signal number estimation unit 107, the arrival signal power estimation unit 108, and the beam reception unit 109. Even if the power difference of the incoming signals is small, signal separation can be performed by the eigenvector beam space method. Furthermore, according to the present embodiment, even two incoming signals of the same power that could not be separated at all can be separated. Further, by providing the signal selection unit 112, a desired output can be selected from the outputs of the eigenvector beam space method.

(Second Embodiment)
The adaptive array antenna apparatus according to this embodiment is characterized by an incoming signal power estimation unit. Since other components are the same as those in the first embodiment, description thereof is omitted.

  In the present embodiment, as shown in FIG. 5, a function shared by the incoming signal power estimation unit 501 and the beam receiving unit 109 and a shared function / function output storage unit 502 that stores the output of the shared function are newly provided.

  The incoming signal power estimation unit 501 uses the same functions as some of the functions used by the beam receiving unit 109 to estimate the power of the incoming signal, and is the same as part of the function output used by the beam receiving unit 109. Use the function. Therefore, in the present embodiment, these shared functions and a part of the shared function output are stored.

  The shared function / function output storage unit 502 stores these functions because some of the functions used by the incoming signal power estimation unit 501 and the functions used by the beam reception unit 109 are the same function. . Further, the shared function / function output storage unit 502 stores the outputs of the functions used by the incoming signal power estimation unit 501 and the outputs of the functions used by the beam receiving unit 109 in part. .

Next, an example of operations performed by the incoming signal power estimation unit 501 and the beam reception unit 109 according to the present embodiment will be described with reference to FIG.
The beam receiving unit 109 divides the array antenna into a plurality of subarrays (step S601). The beam reception unit 109 directs the beam directions of the plurality of subarrays toward the arrival direction, and obtains a plurality of beam reception signals in this state (step S602). The method in these steps S601 and S602 is the same as that described with reference to FIG. 2 in the first embodiment.

Next, the incoming signal power estimation unit 501 calculates a correlation matrix from the beam reception signals of the subarray as in the correlation matrix calculation unit 301 of the first embodiment (step S603). The incoming signal power estimation unit 501 calculates a plurality of eigenvalues of the correlation matrix like the eigenvector calculation unit 302 of the first embodiment (step S604). The number of eigenvalues is equal to the order of the matrix. The order of the matrix is equal to the number of beam reception signals. The number of beam reception signals is equal to the number of subarrays. That is, as many eigenvalues as the number of subarrays are calculated.
The incoming signal power estimation unit 501 calculates the ratio of the plurality of eigenvalues (step S605). The incoming signal power estimation unit 501 calculates eigenvalue ratios for all directions of arrival (step S606). That is, steps S602 to S605 are repeated for all arrival directions. Here, all the arrival directions mean all directions estimated by the arrival direction estimation unit 107 (see FIG. 5).

  Then, the incoming signal power estimation unit 501 estimates the power order of the incoming signals using the ratio of these eigenvalues (step S607). The beam receiving unit 109 selects necessary data and passes it to the signal separation unit 111 (step S608).

Hereinafter, it will be described in detail that the power order of the incoming signals can be estimated using the eigenvalues.
It is known that the eigenvalue is closely related to the power of the incoming signal. Hereinafter, the description of the nature of the eigenvalue is continued when the number of incoming signals is 2 and the number of subarrays is 3.
In this case, three eigenvalues are calculated. The eigenvalues are set to λ ₁ , λ ₂ , and λ ₃ in descending order (that is, λ ₁ > λ ₂ > λ ₃ ). At this time, λ ₁ is proportional to the power of the incoming signal with the higher power, λ ₂ is proportional to the power of the incoming signal with the lower power, and λ ₃ is proportional to the internal noise power. That is, the ratio of the power of the incoming signal 1 and the power of the incoming signal 2 can be found by taking the ratio of λ ₁ and λ ₂ . Thus, the eigenvalue has a property representing the power of the incoming signal. Therefore, the arrival signal power is estimated using this property.

  Hereinafter, two signals of the incoming signal A and the incoming signal B are handled, and the power of the incoming signal A> the power of the incoming signal B is set.

  Here, a state in which the beam of the subarray is directed to the incoming signal A is considered. At this time, the incoming signal A is received by a beam having a high gain, and the incoming signal B is received by a side lobe having a low gain. That is, each signal is received with a different gain depending on the beam of the subarray. Compared with the power difference between the original arrival signal A and the arrival signal B, the power difference is further increased by receiving with the subarray beam.

  Next, a state in which the subarray beam is directed to the incoming signal B is considered. At this time, the incoming signal A is received by a side lobe having a low gain, and the incoming signal B is received by a beam having a high gain. That is, each signal is received with a different gain by the subarray beam. Compared to the power difference between the original arrival signal A and the arrival signal B, the power difference is reduced by receiving with the subarray beam.

In summary, the subarrays to the incoming signal A towards the ratio of the eigenvalues lambda ₁ and lambda ₂ when directing the beam, the sub-array to the incoming signal B beam was of the eigenvalues lambda ₁ and lambda ₂ when directed Larger than the ratio. From the above, it is determined that the power of the incoming signal in the beam direction which is suitable when the ratio of λ ₁ and λ ₂ increases is large.

  According to the second embodiment described above, the magnitude of the power of the incoming signal can be estimated by calculating the beam output of the subarray. A part of this calculation includes the same calculation as that of the adaptive array antenna apparatus of the first embodiment. Since the same calculation can be omitted, the calculation amount of the entire adaptive array antenna apparatus can be reduced. For the purpose of shortening the calculation time, two identical calculation means may be prepared. In this case, since the same apparatus is used, it is possible to contribute to reduction of development costs.

The above description is for the case where the number of incoming signals is two. In general, when the number of incoming signals is L (> 2) waves, the following may be performed. The incoming signal in the beam direction when the ratio of λ ₁ and λ ₂ is maximized is the incoming signal with the highest power. The incoming signal in the beam direction when the ratio of λ ₂ and λ ₃ is maximized becomes the second highest power incoming signal. That is, the incoming signal in the beam direction when the ratio of λ _k to λ _{k + 1} is the maximum is the k-th incoming signal with the highest power.

(Third embodiment)
The adaptive array antenna apparatus according to the present embodiment is characterized by the arrival direction / arrival signal number estimation unit 701. Since other components are the same as those in the first embodiment, description thereof is omitted.

  In the present embodiment, as shown in FIG. 7, a shared function storage unit 702 that stores a function shared by the arrival direction / arrival signal number estimation unit 701 and the signal separation unit 111 is newly provided.

  The arrival direction / arrival signal number estimation unit 701 uses the same functions as some of the functions used by the signal separation unit 111 in order to estimate the arrival direction of the arrival signal. Therefore, in the present embodiment, these shared functions are stored.

  The shared function storage unit 702 stores these functions because some of the functions used in the arrival direction / arrival signal number estimation unit 701 and the functions used in the signal separation unit 111 are the same function. .

Next, the arrival direction / arrival signal number estimation unit 701 will be described with reference to FIG.
The arrival direction / arrival signal number estimation unit 701 includes a correlation matrix calculation unit 801, an eigenvector calculation unit 802, a beam pattern calculation unit 803, and an arrival direction output unit 804. Note that, as shown in the first embodiment, the number of incoming signals can also be obtained using a calculation similar to the following.

  Since the arrival direction / arrival signal number estimation unit 701 includes the same calculation as the signal separation unit 111 described in the first embodiment, the same function is stored in the shared function storage unit 702, and the arrival function is determined. A function can be shared by the direction / arrival signal number estimation unit 701 and the signal separation unit 111.

  Correlation matrix calculation section 801 calculates a correlation matrix from the received signal of the array antenna. The eigenvector calculation unit 802 calculates an eigenvector of the correlation matrix.

The beam pattern calculation unit 803 calculates a beam pattern using the eigenvector as the weight of the array antenna. The beam pattern calculation unit 803 calculates a beam pattern using the weight e _m ^H used when obtaining the m-th eigenvector beam output Zm (t) as the weight of the array antenna.

  The arrival direction output unit 804 outputs the maximum direction of the beam pattern as the arrival direction. The arrival direction output unit 804 estimates the direction of the arrival signal included in the m-th eigenvector beam output Zm (t) from the maximum direction of the obtained beam pattern.

  When the number of arrival signals is L, the arrival directions of the L arrival signals are estimated by estimating the arrival direction using the first eigenvector to the Lth eigenvector.

  According to the above third embodiment, since the same calculation can be omitted in the arrival direction / arrival signal number estimation unit 701 and the signal separation unit 111, the calculation amount of the entire adaptive array antenna apparatus is reduced. It becomes possible to reduce. For the purpose of shortening the calculation time, two identical calculation means may be prepared. In this case, since the same apparatus is used, it is possible to contribute to reduction of development costs.

(Fourth embodiment)
The adaptive array antenna apparatus of this embodiment will be described with reference to FIG.
Unlike the other embodiments, the adaptive array antenna apparatus of this embodiment uses an antenna element that can change the beam direction mechanically or electrically.

  The adaptive array antenna apparatus of this embodiment includes an array antenna unit 901, an arrival direction estimation unit 903, an arrival signal power estimation unit 108, a beam direction control unit 902, a signal separation unit 111, and a signal selection unit 112.

  The array antenna unit 901 includes an antenna element that can change a plurality of beam directions. The antenna element that can change the beam direction is an antenna that can change the beam direction mechanically or electrically.

  An example of an antenna capable of mechanically changing the beam direction will be described. There is a horn antenna placed on a turntable. If the direction of the horn antenna changes, the direction of the beam changes. An example of an antenna capable of electrically changing the beam direction will be described. There is an antenna system including an antenna, a parasitic element arranged in the vicinity, and a variable capacitor connected to the parasitic element. When the value of the variable capacitance is changed, the amount of coupling between the antenna and the parasitic element changes. As a result, the beam direction can be varied. A typical antenna is an Esper antenna. Since these are representative antennas, the present invention is not limited to this, and an antenna that can change the beam direction can be used.

  The arrival direction estimation unit 903 performs the same method as the arrival direction / arrival signal number estimation unit 107 in the first embodiment. Unlike other embodiments, the arrival direction estimation unit 903 does not estimate the number of incoming signals. In this embodiment, since it is not necessary to consider the number of subarrays, it is not necessary to estimate the number of incoming signals. In other embodiments, it is necessary to set the number of subarrays to be larger than the number of incoming signals.

  The beam direction control unit 902 directs the beam in the direction of an incoming signal with high power. The beam direction control unit 902 controls the beam direction of the antenna elements constituting the array antenna using the results of the arrival direction estimation unit 903 and the arrival signal power estimation unit 108.

In the present embodiment, the number of incoming signals that can be separated can be increased. This will be described in detail below.
In other embodiments, the beam is constructed using subarrays. The number of received signals obtained in this way is equal to the number of subarrays. On the other hand, in this embodiment, since the beam direction of the antenna itself is variable, the number of received signals is the number of antenna elements.

  In the eigenvector beamspace method, an eigenvector of a correlation matrix is used as a weight. The number of eigenvectors is equal to the dimension of the correlation matrix. The dimension of the correlation matrix is equal to the number of received signals. Thus, in this embodiment, eigenvectors corresponding to the number of antenna elements can be calculated. The number of eigenvectors is the same as the number of incoming signals that can be separated. Therefore, the present embodiment can increase the number of incoming signals that can be separated compared to other embodiments.

  According to the fourth embodiment described above, since the beam direction of the antenna element can be varied, it is possible to make a difference in gain between incoming signals received by the antenna element. In other embodiments, the number of subarrays is smaller than the number of antenna elements in the beam receiver using a subarray, that is, the number of incoming signals that can be separated is reduced. Since no subarray is used, the number of incoming signals that can be separated is not reduced. That is, a large number of incoming signals can be separated.

  According to the embodiment described above, it is possible to provide an adaptive array antenna apparatus that can perform signal separation by applying the eigenvector beam space method to an arbitrary incoming signal. In addition, a low-cost adaptive array antenna apparatus that does not require a transmitter can be provided. In addition, it is possible to achieve a calibration method, an arrival signal number estimation method, an arrival direction estimation method, an arrival signal power estimation method, downsizing, weight reduction, cost reduction, and high-speed operation of the apparatus.

  Although the adaptive array antenna apparatus has been described above, it can be used in the following fields. When used in the field of wireless communication, the two signals can be separated, so that the communication capacity can be increased. When used in the field of radio wave monitoring, it becomes possible to separate signals that have been mixed. Like cognitive radio, it can be applied to a technical field in which communication is performed after radio wave monitoring.

The instructions shown in the processing procedure shown in the above embodiment can be executed based on a program that is software. A general-purpose computer system stores this program in advance and reads this program, so that the same effect as that obtained by the adaptive array antenna apparatus of the above-described embodiment can be obtained. The instructions described in the above-described embodiments are, as programs that can be executed by a computer, magnetic disks (flexible disks, hard disks, etc.), optical disks (CD-ROM, CD-R, CD-RW, DVD-ROM, DVD). ± R, DVD ± RW, etc.), semiconductor memory, or a similar recording medium. As long as the computer or embedded system can read the storage medium, the storage format may be any form. If the computer reads the program from the recording medium and causes the CPU to execute instructions described in the program based on the program, the same operation as the adaptive array antenna apparatus of the above-described embodiment can be realized. . Of course, when the computer acquires or reads the program, it may be acquired or read through a network.
In addition, the OS (operating system), database management software, MW (middleware) such as a network, etc. running on the computer based on the instructions of the program installed in the computer or embedded system from the storage medium realize this embodiment. A part of each process for performing may be executed.
Furthermore, the storage medium in the present invention is not limited to a medium independent of a computer or an embedded system, but also includes a storage medium in which a program transmitted via a LAN or the Internet is downloaded and stored or temporarily stored.
Also, the number of storage media is not limited to one, and the processing in the present embodiment is executed from a plurality of media, and the configuration of the media is included in the storage media in the present invention.

The computer or the embedded system in the present invention is for executing each process in the present embodiment based on a program stored in a storage medium, and includes a single device such as a personal computer or a microcomputer, Any configuration such as a system in which apparatuses are connected to a network may be used.
Further, the computer in the embodiment of the present invention is not limited to a personal computer, but includes an arithmetic processing device, a microcomputer, and the like included in an information processing device, and a device capable of realizing the functions in the embodiment of the present invention by a program, The device is a general term.

  Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements 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 of the adaptive array antenna apparatus of 1st Embodiment. The figure for demonstrating the direction which directs the beam for every subarray produced | generated in the beam receiving part of FIG. The block diagram of the signal separation part of FIG. The figure which shows the simulation result which evaluated the performance of the adaptive array antenna apparatus of 1st Embodiment. The block diagram of the adaptive array antenna apparatus of 2nd Embodiment. The flowchart which shows an example of the operation | movement performed with the arrival signal power estimation part of FIG. 5, and the beam receiving part of FIG. The block diagram of the adaptive array antenna apparatus of 3rd Embodiment. FIG. 8 is a block diagram of an arrival direction / arrival signal number estimation unit in FIG. 7. The block diagram of the adaptive array antenna apparatus of 4th Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 ... Antenna element, 102 ... Gain amplifier, 103 ... Filter, 104 ... Frequency conversion part, 106, 901 ... Array antenna part, 107, 701 ... Direction of arrival and number of incoming signals Estimating unit 108, 501 ... incoming signal power estimating unit 109 ... beam receiving unit 110 ... digital signal processing circuit 111 ... signal separating unit 112 ... signal selecting unit 201 .. Subarray 202 ... Beam 301, 801 ... Correlation matrix calculator 302, 802 ... Eigen vector calculator 303 ... Eigen vector beam space output calculator 502 ... Shared function / function Output storage unit 702 ... shared function storage unit 803 ... beam pattern calculation unit 804 ... arrival direction output unit 902 ... beam direction control unit 903 ... arrival direction estimation unit.

Claims (10)

An array antenna including a plurality of antenna elements for receiving a plurality of incoming signals;
Direction estimation means for estimating an arrival direction for each of the incoming signals;
Power estimation means for estimating power for each incoming signal;
The array antenna is divided into sub-arrays having a larger number of incoming signals composed of a plurality of antenna elements, and the beam direction of the plurality of sub-arrays is set to the largest power among all the plurality of powers estimated by the power estimation means. In the case where there are a plurality of arrival signals having the largest power among all of the plurality of powers estimated by the power estimation means, the direction estimation means estimates one of the arrival signals. an acquisition unit which directed Ke in the arrival direction is the same, to obtain a plurality of received signals at the antenna array at all the sub-array is,
Separating means for separating the plurality of incoming signals by applying an eigenvector beam space method to the plurality of received signals to obtain and compare eigenvectors ;
An adaptive array antenna apparatus characterized in that signal separation is possible even when there is no power difference between the plurality of incoming signals . The power estimation means includes
Using the acquisition means, the array antenna is divided into subarrays composed of a plurality of antenna elements,
Using the obtaining means, obtaining a plurality of received signals in a state in which the beam directions of the plurality of subarrays are directed to a certain arrival direction among the plurality of arrival directions estimated by the direction estimating means,
Calculating a correlation matrix from a plurality of received signals of the plurality of sub-arrays;
Calculating a plurality of eigenvalues of the correlation matrix;
Calculating a ratio of the plurality of eigenvalues;
Calculating a ratio of eigenvalues for other directions of arrival among a plurality of directions of arrival estimated by the direction estimating means;
The adaptive array antenna apparatus according to claim 1 , wherein the order of power of incoming signals is estimated using a plurality of eigenvalue ratios. An array antenna including a plurality of antenna elements capable of receiving a plurality of incoming signals and changing the beam direction;
Direction estimation means for estimating an arrival direction for each of the incoming signals;
Power estimation means for estimating power for each incoming signal;
An arrival signal having the largest power among all the plurality of powers estimated by the power estimation means or an arrival signal having the largest power among all the plurality of powers estimated by the power estimation means Control means for controlling a plurality of antenna elements to direct a beam in an arrival direction that is the same in all the antenna elements estimated by the direction estimation means of one of the incoming signals when there are a plurality of them ;
Separating means for separating the plurality of incoming signals by applying the eigenvector beam space method to the received signals of the plurality of incoming signals and obtaining and comparing them when the control means controls the plurality of antenna elements. and, the equipped,
An adaptive array antenna apparatus characterized in that signal separation is possible even when there is no power difference between the plurality of incoming signals . The adaptive array antenna apparatus according to any one of claims 1 to 3 , further comprising selection means for selecting a desired signal from the plurality of incoming signals separated by the separation means. . The adaptive array antenna apparatus according to claim 4 , wherein the selection unit selects a signal corresponding to a desired arrival direction among the plurality of arrival directions. The selection means includes modulation scheme estimation means for estimating modulation schemes of the plurality of incoming signals separated by the separation means,
The adaptive array antenna apparatus according to claim 4 , wherein the selection unit selects a signal corresponding to a desired modulation method among a plurality of modulation methods. The separating means includes
Correlation matrix calculation means for calculating a correlation matrix from a plurality of received signals of the array antenna;
Eigenvector calculating means for calculating a plurality of eigenvectors of the correlation matrix;
Using the plurality of eigenvectors as the weight of the array antenna, either a calculating means for calculating a weighted sum of the received signal obtained by the obtaining unit, from claim 1, characterized by comprising of claim 6 1 The adaptive array antenna device according to the item. The direction estimating means includes
Using the correlation matrix calculating means to calculate a correlation matrix from a plurality of received signals of the array antenna;
Using the eigenvector calculating means to calculate eigenvectors of the correlation matrix;
Beam pattern calculating means for calculating a beam pattern using the plurality of eigenvectors as the weight of the array antenna;
The adaptive array antenna apparatus according to claim 7 , further comprising setting means for setting a maximum direction of the beam pattern as an arrival direction. A program used in an adaptive array antenna apparatus including an array antenna including a plurality of antenna elements for receiving a plurality of incoming signals,
Computer
Direction estimation means for estimating an arrival direction for each of the incoming signals;
Power estimation means for estimating power for each incoming signal;
The array antenna is divided into sub-arrays having a larger number of incoming signals composed of a plurality of antenna elements, and the beam direction of the plurality of sub-arrays is set to the largest power among all the plurality of powers estimated by the power estimation means. In the case where there are a plurality of arrival signals having the largest power among all of the plurality of powers estimated by the power estimation means, the direction estimation means estimates one of the arrival signals. an acquisition unit which directed Ke in the arrival direction is the same, to obtain a plurality of received signals at the antenna array at all the sub-array is,
The eigenvector beamspace method is applied to the plurality of received signals to determine and compare eigenvectors, thereby functioning as a separating unit that separates the plurality of incoming signals ,
Because programs to allow even signal separation when there is no power difference of the plurality of incoming signals. A program used in an adaptive array antenna apparatus including an array antenna that includes a plurality of antenna elements that can receive a plurality of incoming signals and change the beam direction,
Computer
Direction estimation means for estimating an arrival direction for each of the incoming signals;
Power estimation means for estimating power for each incoming signal;
An arrival signal having the largest power among all the plurality of powers estimated by the power estimation means or an arrival signal having the largest power among all the plurality of powers estimated by the power estimation means Control means for controlling a plurality of antenna elements to direct a beam in an arrival direction that is the same in all the antenna elements estimated by the direction estimation means of one of the incoming signals when there are a plurality of them ;
Separating means for separating the plurality of incoming signals by applying the eigenvector beam space method to the received signals of the plurality of incoming signals and obtaining and comparing them when the control means controls the plurality of antenna elements. to function as,
Because programs to allow even signal separation when there is no power difference of the plurality of incoming signals.

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