JP2005203961A - Device for controlling array antenna - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To quickly and stably converge the pattern of an electronic control waveguide array antenna instrument by simple processing. <P>SOLUTION: The value of each norm function before and after perturbation is calculated each using two norm functions related to a radio signal received, when the reactance value of each variable reactance element of the electronic control waveguide array antenna is randomly perturbed from a prescribed setting value for setting. When the value of the norm function after the perturbation is increased as compared with that of the norm function before the perturbation for at least one norm function in the two norm functions, each reactance value after the perturbation is set as the new setting value of each reactance value of each variable reactance element. When the value of the norm function after the perturbation becomes that of the norm function before the perturbation, or smaller for both the two norm functions, each reactance value before the perturbation is repeatedly set as the setting value of each reactance value of each variable reactance element. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an array antenna control device for directing an array antenna that includes a plurality of antenna elements and can change directivity characteristics in the direction of a desired wave signal, and in particular, can change adaptive directivity characteristics adaptively. The present invention relates to an array antenna control device using an electronically steerable passive array radiator antenna.

  Adaptive array antennas are a new technology that has received much attention due to its ability to significantly improve the performance of wireless communication systems. However, few studies have focused on how to improve mobile radio terminals using the latest adaptive antenna schemes. Recently, electronically controlled waveguide array antenna devices have been proposed for small adaptive beamforming applied to wireless communication systems.

JP 2001-24431A. T. Ohira, "Renaissance of Analog Beamforming Approach to Adaptive Array Antennas", ISSSE 2001, WE3-B1, July 2001. J. Cheng et al., “Adaptive Beamforming of ESPAR Antenna Based on Steepest Gradient Algorithm”, IEICE Transactions on Communications, Vol. E84-B, No. 7, July 2001. J. Cheng et al., “Sequential Random Search Algorithm for Adaptive Beamforming of ESPAR Antenna”, Technical Report of IEICE, A.P2001-107, RCS2001-146, October 2001. R. Matzner et al., “SNR estimation and blind equalization (deconvolution) using the Kurtosis”, Proceedings of IEEE IMS Workshop on Information Theory Statistics, Alexandria, Virginia, U.S.A., pp.68, October 1994. T. Ohira, "Blind aerial beamforming based on a higher-order maximum moment criterion (part I: Theory)", Proceedings of Asia-Pacific Microwave Conference 2002, pp. 652-655, San Antonio, Texas, U.S.A., June 2002. K. Takizawa et al., “Criterion Diversity: A New Blind Adaptive Beamforming Scheme for ESPAR Antennas”, European Conference on Wireless Technology, European Microwave Week 2003 Conference Proceedings, pp. 245-248, October 2003.

  An electronically controlled waveguide array antenna apparatus proposed in Patent Document 1, Non-Patent Documents 1 to 3 and Non-Patent Document 6 is separated from an excitation element to which a radio signal is fed by a predetermined distance from the excitation element. Provided with an array antenna comprising at least one non-excited element to which no radio signal is fed and a variable reactance element connected to the non-excited element, and changing the reactance value of the variable reactance element, The directivity characteristics of the array antenna can be changed. However, since the signal on the non-excitation element cannot be observed in this electronically controlled waveguide array antenna apparatus, only the output signal of the single port connected to the excitation element is measured, and the reactance value is adaptively controlled. Treated as feedback. Therefore, most of the adaptive control algorithms made for the conventional adaptive array cannot be directly applied to the electronically controlled waveguide array antenna apparatus.

  Among the adaptive beamforming algorithms and norms proposed so far, there are several that can be applied for electronically controlled waveguide array antenna devices. These algorithms include the steepest gradient algorithm (SGA) of Non-Patent Document 2 and the sequential random search algorithm (SRA) of Non-Patent Document 3, and the norm includes the secondary of Non-Patent Document 4 There are a moment and a fourth-order moment (M2M4) norm, a maximum M-th moment norm of Non-Patent Document 5 (M is an integer of 2 or more, hereinafter referred to as MMMC), and the like. Nevertheless, there has been no combination of algorithms and norms that can overcome the trade-off problem between fast convergence and stability. Non-Patent Document 6 discloses the algorithm of the steepest gradient method using M2M4, MMMC, and the maximum moment criterion (MMC). In this case, however, the calculation process for adaptive beam forming becomes very complicated. End up.

  As described above, the adaptive control type algorithm that converges the pattern of the electronically controlled waveguide array antenna device at high speed and stably in a state in which the main beam is directed to the desired wave signal and the null is directed to the interference wave signal. It is desirable to develop. It is also desirable to develop an adaptive control algorithm that steers the beam of an electronically controlled waveguide array antenna device and automatically increases the SIR (signal to interference ratio) of the antenna as much as possible. At the same time, it is desirable that the process of this adaptive control type algorithm is simplified as compared with the conventional algorithm.

  The object of the present invention is to solve the above problems, and to control the array antenna that can converge the pattern of the electronically controlled waveguide array antenna device more quickly and stably by simple processing compared to the prior art. To provide an apparatus.

An array antenna control apparatus according to a first aspect of the present invention includes an excitation element for receiving a radio signal, at least one non-excitation element provided at a predetermined interval from the excitation element, and each of the non-excitation elements. Variable reactance elements connected to each other, and by changing the reactance values of the variable reactance elements, the non-excitation elements are operated as waveguides or reflectors, respectively, and the directivity characteristics of the array antenna are changed. In the array antenna control device,
When the reactance value of each variable reactance element is set by random perturbation from a predetermined set value, the two norms before and after the perturbation are used, using two normative functions related to the radio signal received by the array antenna. Each of the values of the function is calculated and, for at least one of the two normative functions, the normative function value after the perturbation increases relative to the normative function value before the perturbation, the perturbation of the perturbation Each subsequent reactance value is set as a new set value for each reactance value of each variable reactance element, while for both of the two normative functions, the normative function value after the perturbation is the norm before the perturbation. Calculation to set each reactance value before the perturbation as the set value of each reactance value of each variable reactance element when the function value is below And a constant means,
Control means for repeatedly executing the processing of the calculation setting means,
Thus, the reactance value of the variable reactance element for directing the main beam of the array antenna in the direction of the desired wave and directing the null in the direction of the interference wave is calculated and set.

An array antenna control apparatus according to a second invention includes an excitation element for receiving a radio signal, at least one non-excitation element provided at a predetermined distance from the excitation element, and each of the non-excitation elements. A variable reactance element connected to each of the excitation elements, and by changing the reactance value of each of the variable reactance elements, each of the non-excitation elements is operated as a director or a reflector, respectively. In an array antenna control device that changes
When the reactance value of each variable reactance element is set by random perturbation from a predetermined set value, the two norms before and after the perturbation are used, using two normative functions related to the radio signal received by the array antenna. Each of the values of the function is calculated and, for at least one of the two normative functions, the normative function value after the perturbation increases relative to the normative function value before the perturbation, the perturbation of the perturbation Each subsequent reactance value is set as a new set value for each reactance value of each variable reactance element, while the normative function value after the perturbation is the norm before the perturbation for both of the two normative functions. Calculation to set each reactance value before the perturbation as a set value of each reactance value of each variable reactance element when the function value is below And a constant means,
First control means for repeatedly executing the processing of the calculation setting means a predetermined number of times;
After executing the processing of the second means, based on a radio signal received by the array antenna, a predetermined signal-to-noise ratio calculation function including one of the two reference functions is used. Calculating means for calculating a signal-to-noise ratio of the received radio signal;
When the calculated signal-to-noise ratio is lower than a predetermined threshold value, the reactance values of the variable reactance elements are sequentially perturbed by a predetermined shift amount, and the reactance values are calculated based on the radio signals received by the array antenna. The gradient vector of each normative function relating to the value is calculated, and the value of the normative function corresponding to the gradient vector having the maximum norm is calculated based on the gradient vector having the maximum norm among the calculated gradient vectors. Updating means for repeatedly executing the reactance value of each variable reactance element by the steepest gradient method so as to maximize
Second control means for repeatedly executing the processing of the calculation setting means when the calculated signal-to-noise ratio is equal to or greater than the threshold value;
Thus, the reactance value of the variable reactance element for directing the main beam of the array antenna toward the desired wave and the null toward the interference wave is calculated and set.

Furthermore, an array antenna control apparatus according to a third aspect of the present invention includes an excitation element for receiving a radio signal, at least one non-excitation element provided at a predetermined interval from the excitation element, and each of the non-excitation elements. A variable reactance element connected to each of the excitation elements, and by changing a reactance value of each of the variable reactance elements, each of the non-excitation elements is operated as a director or a reflector, respectively. In an array antenna control device that changes
When the reactance value of each variable reactance element is set by random perturbation from a predetermined set value, the two norms before and after the perturbation are used, using two normative functions related to the radio signal received by the array antenna. Each of the values of the function is calculated and, for at least one of the two normative functions, the normative function value after the perturbation increases relative to the normative function value before the perturbation, the perturbation of the perturbation Calculation setting means for setting each subsequent reactance value as a new set value of each reactance value of each variable reactance element;
First control means for repeatedly executing the processing of the calculation setting means a predetermined number of times;
After executing the processing of the second means, based on a radio signal received by the array antenna, a predetermined signal-to-noise ratio calculation function including one of the two reference functions is used. Calculating means for calculating a signal-to-noise ratio of the received radio signal;
When the calculated signal-to-noise ratio is lower than a predetermined threshold value, the reactance values of the variable reactance elements are sequentially perturbed by a predetermined shift amount, and the reactance values are calculated based on the radio signals received by the array antenna. The gradient vector of each normative function relating to the value is calculated, and the value of the normative function corresponding to the gradient vector having the maximum norm is calculated based on the gradient vector having the maximum norm among the calculated gradient vectors. Updating means for repeatedly executing the reactance value of each variable reactance element by the steepest gradient method so as to maximize
Second control means for repeatedly executing the processing of the calculation setting means when the calculated signal-to-noise ratio is equal to or greater than the threshold value;
Thus, the reactance value of the variable reactance element for directing the main beam of the array antenna toward the desired wave and the null toward the interference wave is calculated and set.

Furthermore, an array antenna control apparatus according to a fourth aspect of the present invention includes an excitation element for receiving a radio signal, at least one non-excitation element provided at a predetermined interval from the excitation element, and each of the above-described elements. Variable reactance elements connected to the non-excitation elements, respectively, and by changing the reactance values of the variable reactance elements, the non-excitation elements are operated as directors or reflectors, respectively. In an array antenna control device that changes characteristics,
The range of reactance values that can be taken by each of the variable reactance elements is divided into two, and when the median value of each range after two minutes is set, the two normative functions related to the radio signal received by the array antenna are used. The value of each normative function corresponding to the median value of each range after bisection is calculated, and the normative function value corresponding to the median value of each range after dichotomy for at least one of the two normative functions Calculation setting means for setting each reactance value corresponding to a more increasing normative function value as a new set value of each reactance value of each variable reactance element;
First control means for repeatedly executing the processing of the calculation setting means a predetermined number of times;
After executing the processing of the second means, based on a radio signal received by the array antenna, a predetermined signal-to-noise ratio calculation function including one of the two reference functions is used. Calculating means for calculating a signal-to-noise ratio of the received radio signal;
When the calculated signal-to-noise ratio is lower than a predetermined threshold value, the reactance values of the variable reactance elements are sequentially perturbed by a predetermined shift amount, and the reactance values are calculated based on the radio signals received by the array antenna. The gradient vector of each normative function relating to the value is calculated, and the value of the normative function corresponding to the gradient vector having the maximum norm is calculated based on the gradient vector having the maximum norm among the calculated gradient vectors. Updating means for repeatedly executing the reactance value of each variable reactance element by the steepest gradient method so as to maximize
Second control means for repeatedly executing the processing of the calculation setting means when the calculated signal-to-noise ratio is equal to or greater than the threshold value;
Thus, the reactance value of the variable reactance element for directing the main beam of the array antenna toward the desired wave and the null toward the interference wave is calculated and set.

In the array antenna control apparatus, the two normative functions are preferably:
A first normative function formed by dividing an average value of the fourth power value of the received radio signal in a predetermined period by a square value of the average value of the square value of the received radio signal;
M is an integer greater than or equal to 2, and the square value of the absolute value of the average value of the M power values of the received radio signal in a predetermined period is the square value of the absolute value of the M power value of the received radio signal. And a second normative function obtained by dividing by the average value.

  Therefore, according to the array antenna control apparatus of the present invention, the pattern of the electronically controlled waveguide array antenna apparatus can be converged more quickly and stably by a simple process compared to the prior art.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, the same code | symbol is provided about the same component or step.

<First Embodiment>
FIG. 1 is a block diagram showing a configuration of an array antenna control apparatus according to a first embodiment of the present invention. The array antenna control apparatus of this embodiment is an electronically controlled waveguide array antenna that is configured to include one excitation element A0 and six non-excitation elements A1 to A6, which is disclosed in Patent Document 1. An apparatus (hereinafter referred to as an array antenna apparatus) 100, a demodulator 4, and an adaptive control type controller 20 are provided. The adaptive control type controller 20 is composed of, for example, a digital computer. In this embodiment, as shown in FIGS. 3 and 4, the reactance values of the variable reactance elements 12-1 to 12-6 are randomly set from predetermined set values. 2 (step S8 in FIG. 3), the two reference functions ρ (n) _M2M4 and ρ (n) _MMMC based on the radio signals received by the array antenna apparatus 100 are used to calculate the perturbation. The values ρ (n−1) _M2M4 and ρ (n) _M2M4 and ρ (n−1) _MMMC and ρ (n) _MMMC of the respective reference functions _before and after are calculated (steps S10 and S12 in FIG. 3), respectively. If the normative function value after the perturbation increases with respect to the normative function value before the perturbation for at least one normative function of the two normative functions, The actance value is set as a new set value of each reactance value of each of the variable reactance elements 12-1 to 12-6, while the normative function value after the perturbation for both of the two normative functions is the value of the perturbation. If the value is less than the previous normative function value, the reactance values before the perturbation are set as the set values of the reactance values of the variable reactance elements 12-1 to 12-6 (step S16 in FIG. 4). Iteratively executed, thereby calculating reactance values of the variable reactance elements 12-1 to 12-6 for directing the main beam of the array antenna apparatus 100 in the direction of the desired wave and directing the null in the direction of the interference wave It is characterized by setting.

  In FIG. 1, an array antenna apparatus 100 is composed of an excitation element A0 and non-excitation elements A1 to A6 provided on a ground conductor 11, and the excitation elements A0 are provided on six circumferences having a radius r. They are arranged so as to be surrounded by the non-excitation elements A1 to A6. Preferably, the non-exciting elements A1 to A6 are provided at equal intervals on the circumference of the radius r. The lengths of the excitation element A0 and the non-excitation elements A1 to A6 are configured to be, for example, about λ / 4 (where λ is the wavelength of the desired wave), and in this embodiment is 0.23λ. . The radius r is configured to be λ / 4. As shown in FIG. 2, the ground conductor 11 includes a disk-shaped upper surface portion having a radius λ / 2, and a cylindrical skirt portion having a length λ / 4 extending downward from the outer peripheral edge of the upper surface portion. The elevation angle of the main beam can be reduced by the configuration including the skirt portion. The feeding point of the excitation element A0 is connected to the low noise amplifier (LNA) 1 through the coaxial cable 5. The non-excitation elements A1 to A6 are connected to the variable reactance elements 12-1 to 12-6, respectively. The reactance values of these variable reactance elements 12-1 to 12-6 are the control voltage signals from the adaptive control type controller 20. Respectively.

  In the longitudinal cross-sectional view of the array antenna apparatus 100 of FIG. 2, the excitation element A0 is electrically insulated from the ground conductor 11, and the non-excitation elements A1 to A6 are respectively connected via the variable reactance elements 12-1 to 12-6. The ground conductor 11 is grounded at a high frequency. The variable reactance elements 12-1 to 12-6 are, for example, variable capacitance diodes whose reactance values change when a control voltage (or bias voltage) is applied. The control voltage is supplied from the adaptive control type controller 20. Applied through a control voltage signal. The adaptive control controller 20 refers to a digital voltage value preset in a built-in table memory (not shown), and uses the six built-in D / A converters (not shown) to perform the above. The digital voltage value is converted into an analog control voltage value, and this control voltage value is applied as a control voltage signal to each of the variable reactance elements 12-1 to 12-6 of the array antenna device 100. Each corresponding directional beam pattern is formed.

  The operation of the variable reactance elements 12-1 to 12-6 will be described. For example, when the longitudinal lengths of the excitation element A0 and the non-excitation elements A1 to A6 are substantially the same, for example, the variable reactance element 12-1 Is inductive (L property), the variable reactance element 12-1 becomes an extension coil, and the electrical length of the non-excitation element A1 is longer than that of the excitation element A0, and acts as a reflector. On the other hand, for example, when the variable reactance element 12-1 has capacitance (C-type), the variable reactance element 12-1 becomes a shortening capacitor, and the electrical length of the non-excitation element A1 becomes shorter than that of the excitation element A0. Acts as a director. The non-excitation elements A2 to A6 connected to the other variable reactance elements 12-2 to 12-6 operate in the same manner. Therefore, in the array antenna apparatus 100 of FIG. 1, the plane directivity characteristics of the array antenna apparatus 100 are changed by changing the reactance values of the variable reactance elements 12-1 to 12-6 connected to the non-excitation elements A1 to A6. Can be changed.

In the array antenna control apparatus of FIG. 1, the array antenna apparatus 100 receives a radio signal, and the received signal, which is the received radio signal, is output from the coaxial cable 5 connected to the excitation element A0. The output reception signal is input to a low noise amplifier (LNA) 1, the reception signal amplified in the low noise amplifier 1 is input to a down converter (D / C) 2, and the down converter 2 receives an input reception signal. Is converted to an intermediate frequency signal having a predetermined intermediate frequency and then output to the A / D converter 3. The A / D converter 3 converts the input analog intermediate frequency signal into a digital intermediate frequency signal, and then outputs it to the adaptive control controller 20 and the demodulator 4. Further, as shown in FIGS. 3 and 4, the adaptive control controller 20 sets the reactance values of the variable reactance elements 12-1 to 12-6 randomly perturbed from predetermined set values (FIG. 3). In step S8), two normative functions ρ (n) _M2M4 and ρ (n) _MMMC based on the radio signals received by the array antenna apparatus 100 are used to determine the value ρ (n of each normative function before and after the perturbation. -1) _M2M4 and ρ (n) _M2M4 and ρ (n-1) _MMMC and ρ (n) _MMMC are respectively calculated (steps S10 and S12 in FIG. 3), and at least one of the two normative functions is calculated. If the normative function value after the perturbation for one normative function increases with respect to the normative function value before the perturbation, each reactance value after the perturbation is changed to each variable reactance element 12. If the reactance values of 1 to 12-6 are set as new set values while the normative function value after the perturbation is less than the normative function value before the perturbation for both of the two normative functions For example, the step of setting the reactance values before the perturbation as the set values of the reactance values of the variable reactance elements 12-1 to 12-6 (step S16 in FIG. 4) is repeatedly executed. The reactance values of the variable reactance elements 12-1 to 12-6 for directing the main beam of the array antenna apparatus 100 in the direction of the desired wave and directing the null in the direction of the interference wave are calculated and set.

  Hereinafter, the adaptive control process executed by the adaptive control type controller 20 will be described in detail. First, the structure and operation of the array antenna apparatus 100 of FIG. 1 are formulated, and then each step of the adaptive control process will be described.

The directivity pattern of the array antenna apparatus 100 is to adjust the reactance values x _m , mε (1,..., 6) of the variable reactance elements 12-1 to 12-6 loaded on the non-excitation elements A1 to A6. Can be changed. For this reason, the vector represented by the following equation is called a reactance vector. Here, the superscript ^T is a transpose of the vector. In this specification, the number number of the black brackets in which the mathematical formula is imaged and the formula number of the square brackets in which the mathematical formula is input are used in combination. The formula number is assigned to the last part of the formula using the formula (1) as the formula number (there is also a formula that is not given).

[Equation 1]
x = [x ₁ , x ₂ ,..., x ₆ ] ^T (1)

Thus, the output signal of the array antenna apparatus 100 can be easily formulated. When s _m (t) is an RF signal incident on the m-th antenna element Am (that is, one of the excitation element A0 or the non-excitation elements A1 to A6) at time t, the signal vector s (t) is It is expressed by the following formula.

[Equation 2]
s (t) = [s ₀ (t), s ₁ (t),..., s ₆ (t)] ^T (2)

Further, when the i _m is an RF current appearing on the m-th antenna element Am, represents a current vector i by the following equation.

[Equation 3]
i = [i ₀ , i ₁ ,..., i ₆ ] ^T (3)

  Therefore, the reception signal y (t) output from the single port of the array antenna apparatus 100 at time t is formulated by the following equation.

[Equation 4]
y (t) = i ^T s (t) (4)

  When the wavefront of a radio signal arriving at the array antenna apparatus 100 is incident at an angle of arrival (DOA) θ, the steering vector of the array antenna apparatus 100 is defined by the following equation.

Here, φ _m = 2π (m−1) / 6, (m = 0, 1,..., 6), and these indicate the azimuth angle at which the non-excitation element A1 is located with respect to the excitation element A0 is 0 degree. This is a constant indicating the azimuth angle at which each non-excitation element Am is located when the direction is set.

Thus, there are Q signals u _q (t) incident on the array antenna apparatus 100 from azimuth angles θ _q , (q = 0, 1, 2,..., Q) which are different DOAs at time t. Assume that Here, let s _m (t), (m = 0, 1,..., 6) be a signal arriving at the m-th antenna element Am of the array antenna apparatus 100, and let the signal vector s (t) be m-th. Assuming that a column vector having s _m (t) as a component, as a result, the signal vector s (t) is expressed as follows.

  Therefore, reception signal y (t) output from array antenna apparatus 100 at time t is defined by the following equation.

In Expression (7), the received signal is represented as the received signal y (t) measured by the adaptive control type controller 20 at time t. Hereinafter, the number of iterations of the adaptive control process executed by the adaptive control type controller 20 will be described. A description will be given using this notation, where n is a parameter, and y (n) is a received signal measured by the adaptive control controller 20 in the nth iteration. In addition, the reactance vectors set in the variable reactance elements 12-1 to 12-6 in the n-th iteration of the adaptive control process executed by the adaptive control controller 20 are x (n) = [x ₁ (n),. , X ₆ (n)] ^T. Therefore, the received signal y (n) is a received signal measured by the adaptive control type controller 20 when the reactance vector x (n) is set in each of the variable reactance elements 12-1 to 12-6.

  Further, the current vector i can be formulated according to Non-Patent Document 1 as follows.

[Equation 5]
i = V _s (Z + X) ⁻¹ u ₀ (8)

Here, X = diag [50, jx ₁ ,..., Jx ₆ ] is called a reactance matrix, and Z is an impedance matrix whose components are impedances between the antenna elements A0 to A6, and is a (6 + 1) -dimensional vector. u ₀ is [1, 0,..., 0] ^T, and V _s is the internal source RF voltage.

  Next, the concept of normative function diversity applied to the adaptive control type algorithm will be described. Generally, in conventional adaptive control type algorithms, beam forming is performed using only one reference function. Table 1 shows two reference functions that can be used for blind adaptive beamforming of the array antenna apparatus 100 and their characteristics. These normative functions are blind. That is, the same training symbol (or learning sequence signal) is generated in the transmitting radio station and the receiving radio station, and the training symbol of the receiving radio station is compared with the received training symbol of the transmitting radio station. Is used, and only the radio signal received by the receiving radio station is used. The blind reference functions used in this embodiment are M2M4 and MMMC. The normative function of M2M4 is an average value of the fourth power of the received signal y (n) (that is, the fourth moment) of the received signal y (n) in a predetermined period. ) Divided by the square value. The normative function of MMMC is that M is an integer equal to or greater than 2, and the square value of the absolute value of the average value of the M power values of the received signal y (n) in a predetermined period is the M power of the received signal y (n). It is a function obtained by dividing by the average value of the square value of the absolute value.

In Table 1, ρ (n) represents a normative function value, n represents the number of iterations of adaptive control processing executed by the adaptive control type controller 20, and Ns represents the number of samples of statistical moments. Accordingly, in the reference function value ρ (n), the reactance vector x (n) is set to each of the variable reactance elements 12-1 to 12-6 in the nth iteration of the adaptive control process executed by the adaptive control type controller 20. Is calculated based on the received signal y (n) measured by the adaptive control type controller 20. Actually, as can be seen from the equations in Table 1, the normative function value ρ (n) is obtained by Ns samples y (n) _{1 to} y () of the received signal y (n) output from the array antenna apparatus 100. n) Calculated from _Ns . In the present specification, for simplification of the following description, it is assumed that Ns samples y (n) _{1 to} y (n) _Ns are represented by the notation “received signal y (n)”.

Hereinafter, the M2M4 normative function described in Table 1 is denoted as ρ (n) _M2M4, and the MMMC normative function is denoted as ρ (n) _MMMC .

  Unfortunately, Table 1 shows that both normative functions have a trade-off between their convergence speed and stability.

  To overcome this problem and achieve blind adaptive beamforming with faster and more stable convergence, both of these normative functions may be used in an adaptive control algorithm. This is the basic principle of normative function diversity. This principle is actually used in the adaptive control process of the embodiment according to the present invention, and for each iteration of the loop of the adaptive control process, which criterion is the best for calculation.

  Next, the adaptive control processing by the sequential random search method using the reference function diversity executed by the adaptive control type controller 20 of FIG. 1 will be described with reference to FIGS. The sequential random search method is one of the main algorithms of adaptive beam forming according to the present embodiment. This is a reactance vector x (n) having the reactance values of the variable reactance elements 12-1 to 12-6 as components. Is randomly changed for each iteration of the loop. According to the basic principle of this algorithm, the process proceeds as follows.

In step S1 of FIG. 3, the number of iterations n is initialized to zero. In step S2, a control voltage signal corresponding to the initial value x (0) of the reactance vector x (n) is output and set to each variable reactance element 12-1 to 12-6. In general, the reactance vector x (0) is set to a zero vector that provides an omnidirectional antenna pattern. In step S3, the received signal y (n) is measured. In step S4, based on the received signal y (n) measured in step S3, a normative function value ρ (n) _M2M4 of _M2M4 is calculated using equation (9), and in step S5, measured in step S3. Based on the received signal y (n), the reference function value ρ (n) _MMMC of _MMMC is calculated using Equation (10). The order in which steps S4 and S5 are performed may be reversed or simultaneous. Next, in step S6, the number of iterations n is incremented by one. In step S7, a randomly generated random vector R (n) having six components is generated. In step S8, a reactance vector x (n-1) + R (n changed by the random vector R (n) is generated. ) Are output to the variable reactance elements 12-1 to 12-6 and set. In step S9, the received signal y (n) is measured. In step S10, based on the received signal y (n) measured in step S9, a normative function value ρ (n) _M2M4 of _M2M4 is calculated using equation (9). In step S11, a random vector R (n ), The difference value Diff _M2M4 of the M2M4 normative function value before and after the reactance vector is changed is subtracted from the normative function value ρ (n) _M2M4 after the change, and the normative function value ρ (n−1) _M2M4 before the change. By calculating. Next, in step S12, based on the received signal y (n) measured in step S9, the MMMC normative function value ρ (n) _MMMC is calculated using equation (10). In step S13, the random vector R The difference value Diff _MMMC of the _reference function value of the MMMC before and after the reactance vector is changed by (n), and the _reference function value ρ (n−1) _MMMC before the change from the reference function value ρ (n) _MMMC after the change. Calculate by subtracting. The order of executing steps S10 and S11 and steps S12 and S13 may be reversed or simultaneous.

Next, in steps S14 and S15 of FIG. 4, whether or not the update of the reactance vector x (n) (ie, the change due to the random vector R (n)) is appropriate by referring to the normative function that yields a larger difference value. To decide. Specifically, in step S14, when the difference value _{Diff M2M4} by M2M4 the difference value _Diff is a _MMMC or more and the difference value _{Diff M2M4} by MMMC is a positive value, or, in step S15, the difference value _{Diff MMMC} by MMMC M2M4 When the difference value Diff _M2M4 is greater than the difference value Diff _M2M4 and the difference value Diff _MMMC is a positive value, it is determined that the change by the random vector R (n) is appropriate, and the process proceeds to step S17. In steps S14 and S15, if the difference values Diff _M2M4 and Diff _MMMC calculated using two normative functions are both negative values, the change due to the random vector R (n) is rejected, and then in step S16 The control voltage signal corresponding to the reactance vector x (n−1) in the previous iteration is output and set to each of the variable reactance elements 12-1 to 12-6, and the process proceeds to step S17.

  In the processes of steps S14 to S16, which of the M2M4 and MMMC normative functions is actually referenced does not affect the update of the reactance vector x (n). Therefore, when the normative function value after perturbation by the random vector R (n) increases with respect to the normative function value before perturbation for at least one normative function of the two normative functions (step S14 or S15 is YES) ), The reactance values after perturbation are set as new set values of the reactance values of the variable reactance elements 12-1 to 12-6, while the norm function after perturbation is performed for both of the two norm functions. When the value is equal to or less than the reference function value before perturbation (when both S14 and S15 are NO), the reactance value before perturbation is set to the reactance value of each variable reactance element 12-1 to 12-6. Set as a value (step S16).

  In step S17, it is determined whether or not the number of iterations n has reached a preset maximum number of iterations N. If n <N, the process returns to step S6, and if n ≧ N, the process ends.

  In this embodiment, in order to realize normative function diversity, two normative functions of M2M4 and MMMC are used. However, adaptive control processing may be executed using three or more normative functions. These normative functions are preferably different from one another in convergence speed, stability, and / or other characteristics.

  As described above, according to the array antenna control method and control apparatus of the present embodiment, the problem of the tradeoff between the convergence speed and the stability is solved, and compared with the prior art, the processing is simpler. Calculate the reactance value of the variable reactance element to converge the pattern of the electronically controlled waveguide array antenna device at high speed and stably, and to direct the main beam of the array antenna toward the desired wave and the null toward the interference wave. Can be set.

<Second Embodiment>
In the present embodiment, in order to control the directivity of the array antenna apparatus 100, algorithm diversity using two algorithms of a sequential random search method and a steepest gradient method is adopted, and at the same time, these two algorithms are respectively It is characterized by adopting a normative function diversity using an M2M4 normative function and an MMMC normative function. Specifically, in the present embodiment, the adaptive control controller 20 includes a first step executed in the same manner as the adaptive control processing by the sequential random search method using the normative function diversity of the first embodiment, A second step that repeats the processing of the step a predetermined number of times, and after executing the processing of the second step, one of two reference functions based on the radio signal received by the array antenna apparatus 100 A third step of calculating a signal to noise ratio (SNR) value of the received radio signal using a signal to noise ratio calculation function associated with the reference function of When the value is lower than the threshold value, the reactance values of the variable reactance elements 12-1 to 12-6 are sequentially perturbed by a predetermined shift amount and received by the array antenna apparatus 100. Using two criterion function ρ _{(n) M2M4} and ρ _{(n) MMMC} based on radio signals, calculate gradient vector ∇ρ of each criterion function for each reactance value _{(n) M2M4} and ∇ρ a _{(n) MMMC} respectively Then, based on the gradient vector having the maximum norm among the calculated gradient vectors, the steep gradient method is used so that the value of the reference function corresponding to the gradient vector having the maximum norm is maximized. The fourth step of repeating updating the reactance values of the variable reactance elements 12-1 to 12-6, and the process of the first step is repeated when the calculated SNR value is equal to or greater than the threshold value. And a variable for directing the main beam of the array antenna in the direction of the desired wave and in the direction of the interference wave. And setting by calculating the reactance value of the reactance element. Further, in the present embodiment, only the adaptive control process executed by the adaptive control type controller 20 of FIG. 1 is different from the first embodiment, and other components in the present embodiment are the same as those in the first embodiment.

  First, compare two different algorithms that use normative function diversity. Here, the adaptive control processing by the sequential random search method using the reference function diversity described as the first embodiment of the present invention and the adaptation by the steepest gradient method using the reference function diversity described in Non-Patent Document 6. Discuss the advantages of each with control processing.

  First, referring to a simulation result according to the first embodiment, which will be described later, the convergence curve in FIG. 11 shows that an algorithm that uses normative function diversity is an algorithm that uses only an M2M4 normative function or only an MMMC normative function. Compared to the above, it is shown that better blind adaptive beamforming is realized. Further, with reference to Non-Patent Document 6, assuming that adaptive control processing by the steepest gradient method using the norm function diversity of M2M4 and MMMC is executed, the norm for the electronically controlled waveguide array antenna apparatus The characteristics of both adaptive beamforming algorithms using function diversity can be shown in Table 2.

  Actually, according to the simulation conducted by the present inventors, when the value of the signal-to-noise ratio (SNR) is high (in the case of about 20 dB), the adaptive control processing by the sequential random search method using the reference function diversity is performed. It has been found that if is executed, a beam can be formed in the direction in which the desired wave signal exists, and a deep null can be formed toward the interference wave signal. Conversely, when the SNR value is a low value, the steepest gradient method is much more efficient than the sequential random search method. Normally, the SNR value cannot be known, and both the steepest gradient method and the sequential random search method are effective in different situations. Therefore, in the present embodiment, the steepest gradient method using the reference function diversity and the reference function This paper proposes adaptive control processing by both algorithms of sequential random search method using diversity.

  In addition, processing duration issues may be encountered. Actually, since the algorithm of the steepest gradient method is more complicated than the algorithm of the sequential random search method, the calculation process of the algorithm of the steepest gradient method takes much longer time. This is due to the fact that the steepest gradient method has to calculate the reference function value every time the reactance value is perturbed for each of the variable reactance elements 12-1 to 12-6 of the seven-element array antenna apparatus 100. Can be explained. The steepest gradient method can form both beams and nulls in the directivity pattern of the array antenna apparatus 100 even when the SNR value is high. However, the processing complexity of the steepest gradient method is that of the sequential random search method. It is much better than processing, and for this reason, it is better to use the random search method sequentially when the SNR value is high. The steepest gradient method is more efficient than the sequential random search method under predetermined conditions in which the desired wave signal and the interference wave signal have substantially the same power.

  Next, an adaptive control process using algorithm diversity and reference function diversity executed by the adaptive control controller 20 will be described with reference to FIGS. The main principle of this adaptive control process is to combine the steepest gradient method using normative function diversity with the sequential random search method using normative function diversity. As a result, the adaptive control process according to the present embodiment improves the directivity pattern of the array antenna apparatus 100 regardless of the power value and SNR value of the incident signal.

  The adaptive control processing according to the present embodiment is characterized in that the algorithm to be used is switched according to the SNR value of the received signal in the course of calculating the reactance value. In order to calculate the SNR value in the present embodiment, based on the principle described in Non-Patent Document 6, it is based on the normative function value calculated using Equation (9) and Equation (10).

Reference function ρ (n) of _{M2M4 The} following describes that _M2M4 has a predetermined relationship with the SNR value of the received signal y (n). Here, E [] is used as an operator of the statistical expectation value, and the following generalized M2M4 normative function ρ (n) ₁ will be used.

  Further, it is assumed that the reception signal y (n) is modeled by a simple sum of the transmission signal σ (n) and additive white Gaussian noise (AWGN) ν (n) as in the following equation.

  Here, S and N are the power of the signal and the noise signal, respectively. If the number of interference signals is sufficiently large, the interference signals are included in the signal component ν (n) of AWGN.

  Substituting equation (12) into equation (11) yields:

Here, gamma is given by γ = S / N, an SNR value for each bit of the signal, respectively _{K s} and _{K n,} the kurtosis of the transmission signal sigma (n) and the noise signal [nu (n) Show. These kurtosis are given by:

The kurtosis K _s of the transmission signal takes different values according to the modulation scheme of the transmission signal σ (n), whereas the kurtosis K _{n of the} noise signal is 3 or 2 in the real or complex AGWN channel, respectively. From equation (13), it can be seen that the normative function value ρ (n) ₁ approaches K _s when the SNR value γ increases. Thus, adaptive control processing based on the M2M4 normative function ρ (n) ₁ is achieved by maximizing the normative function value ρ (n) ₁ using an adaptive algorithm.

Here, by solving the equation (13) with respect to the SNR value γ, an M2M4 calculation function for calculating the SNR value γ can be obtained from the M2M4 normative function value ρ (n) ₁ as shown in the following equation. .

[Equation 6]
γ = F ₁ (ρ (n) ₁ ) (16)

In the adaptive control processing of the present embodiment, a set of the normative function of Equation (9) and the calculation function of Equation (16) is used as a signal-to-noise ratio calculation function, and the normative function value calculated using Equation (4). By _substituting ρ (n) _M2M4 into the normative function value ρ (n) ₁ of Equation 6, the SNR value of the received signal y (n) is calculated.

Next, it will be described below that the MMMC normative function ρ (n) _MMMC also has a predetermined relationship with the SNR value of the received signal y (n). Here, E [] is used as an operator of the statistical expectation value, and the following generalized MMMC normative function ρ (n) ₂ is used for explanation.

  When the transmission signal σ (n) is an M-ary PSK signal, the M value of the signal value at each time is a unique complex value. In accordance with this fact, the numerator and denominator of equation (17) respectively represent the power and dispersion measured by the unique complex value.

  By substituting equation (11) into equation (17), the following equation is obtained.

Equation (18) shows that the MMMC normative function ρ (n) ₂ increases monotonically with respect to the SNR value γ. Accordingly, the adaptive control process based on the MMMC normative function ρ (n) ₂ is achieved by maximizing the normative function value ρ (n) ₂ .

Further, by solving the equation (18) for the SNR value γ, the calculation function of the MMMC for calculating the SNR value γ can be obtained from the MMMC normative function value ρ (n) ₂ as the following equation.

[Equation 7]
γ = F ₂ (ρ (n) ₂ ) (19)

In the adaptive control processing of the present embodiment, a set of the reference function of Expression (10) and the calculation function of Expression (19) is used as a signal-to-noise ratio calculation function, and the reference function value calculated using Expression (10). ρ (n) The SNR value of the received signal y (n) is calculated by substituting _MMMC for the reference function value ρ (n) ₂ in equation (19).

  The adaptive control process using algorithm diversity and reference function diversity basically proceeds as follows.

In step S1 of FIG. 5, the number of iterations n is initialized to 0, and the normative function flag CF is set to 0 in step S1a. The reference function flag CF is a flag for designating a reference function and a calculation function used when calculating the SNR value of the received signal. In this embodiment, CF = 0 indicates that the M2M4 reference function and the calculation function are used. This means that CF = 1 uses the MMMC normative function and calculation function, but the meaning of the flag may be set in reverse. Subsequent steps S2 to S5 are the same as in the first embodiment. Next, in step S21, an initial adaptive control process is sequentially performed by a random search method, and the process in step S21 is repeated until it is determined in step S22 that the number of iterations n has reached a predetermined number N _SNR . FIG. 6 shows a flowchart of a subroutine related to the initial adaptive control process S21 by the sequential random search method. Steps S6 to S13 in FIG. 6 are the same as the respective steps in FIG. When step S14 in FIG. 6 (same as step S14 in FIG. 4) is YES, the value of the normative function flag CF is set to 0 in step S14a, and the process proceeds to step S22 in FIG. When step S14 is NO and step S15 (same as step S15 in FIG. 4) is YES, the value of the normative function flag CF is set to 1 in step S15a, and the process proceeds to step S22 in FIG. When steps S14 and S15 are both NO, step S16 (similar to step S16 in FIG. 4) is executed, and the process proceeds to step S22 in FIG. Steps S6 to S16 in FIG. 6 are repeated while the number of iterations n is 1 to N _SNR .

If n ≧ N _SNR is determined in step S22, then the received signal y (n) is measured in step S23, and the SNR value is determined in step S24 based on the received signal y (n) measured in step S23. Calculate In order to calculate the SNR value in step S24, the reference function flag CF is referred to. When CF = 0, the M2M4 reference function of Expression (9) and the calculation function of Expression (16) are used. When 1, the MMMC normative function of equation (8) and the calculation function of equation (19) are used. Accordingly, the normative function and the calculation function used to calculate the SNR value are substantially the last update in the process of step S21 (that is, the last update in which one of steps S14 and S15 in FIG. 6 is YES). , Based on which of steps S14 and S15 is YES, that is, whether the reactance vector x (n) is updated with reference to the M2M4 norm function or the MMMC norm function (9) And a set of Expression (16) or a set of Expression (10) and Expression (19). If it is determined in step S25 that the calculated SNR value is smaller than 10 dB (or a predetermined threshold value set in advance), the steepest gradient method of step S26 is performed in the N _SNR + 1st to Nth iterations. The first adaptive control process is executed. On the other hand, when it is determined in step S25 that the calculated SNR value is 10 dB or more, the second adaptive control process by the sequential random search method in step S26 is executed in the iteration from N _SNR +1 to N times. To do.

Here, the steepest gradient method using normative function diversity executed in step S26 will be described. The processing algorithm in this step is an algorithm that uses normative function diversity and is based on the gradient of the normative function for the electronically controlled waveguide array antenna apparatus. Refer to the technique described in Non-Patent Document 6. Is done. This algorithm is similar to the adaptive control processing by the sequential random search method using the reference function dice in the first embodiment, and both the M2M4 and MMMC blind reference functions ρ (n) _M2M4 and ρ (n) _MMMC is used. For simplification, when a common explanation is given to two normative functions, the normative function is expressed as ρ (n).

  The gradient vector of the reference function ρ (n) is expressed by the following equation.

Here, the gradient vector ∇ρ (n) is obtained by partial differentiation of the reference function ρ (n) with respect to each component of the reactance vector x (n). That is, component δρ (n) / δx _m of the gradient vector is a partial differential coefficient of the criterion function is calculated as follows.

Here, the reference value ρ (n) ⁽⁰⁾ of the normative function indicates that the reactance vector x (n) = [x ₁ (n),..., X ₆ (n)] is an array in the nth iteration of the adaptive control process. The reference function value ρ (n) is a value calculated when the antenna device 100 is set, and the reactance vector x (n) = [x ₁ () in which the m-th component is perturbed by a predetermined reactance value Δx _m. , x _m (n) + Δx _m ,..., x ₆ (n)] are values calculated when the array antenna device 100 is set. As described above, the normative function ρ (n) of Equation (21) is either the M2M4 normative function ρ (n) _M2M4 or the MMMC normative function value ρ (n) _MMMC .

7 and 8 are flowcharts of a subroutine related to the first adaptive control process S26 by the steepest gradient method. In step S31 of FIG. 7, the parameter m corresponding to each antenna element A0 to A6 is set to 0, and in step S32, the received signal y (n) is measured. In step S33, based on the received signal y (n) measured in step S32, the M2M4 normative function value ρ (n) _M2M4 is calculated using equation (9), and this is the reference value of the M2M4 normative function. Let ρ (n) _M2M4 ⁽⁰⁾ . In step S34, based on the received signal y (n) measured in step S32, an MMMC normative function value ρ (n) _MMMC is calculated using equation (10), and this is calculated as a reference value of the MMMC normative function. Let ρ (n) _MMMC ⁽⁰⁾ . The order in which steps S33 and S34 are performed may be reversed or simultaneous. Next, in step S35, the parameter m is incremented by 1. In step S36, a control voltage signal corresponding to a reactance vector in which only the _mth component is changed by a predetermined reactance value + Δxm is output to each variable reactance element 12-1 to 12-6 and set. In step S37, the received signal y (n) is measured. In step S38, based on the received signal y (n) measured in step S37, the normative function value ρ (n) _M2M4 is calculated using equation (9). In step S39, the normative function value ρ (n) _{Based on M2M4} and the reference value ρ (n) _M2M4 ⁽⁰⁾ , the partial differential coefficient δρ (n) _M2M4 / δx _m of the norm function is calculated using Equation (21). Next, in step S40, based on the received signal y (n) measured in step S37, a normative function value ρ (n) _MMMC is calculated using equation (8). In step S41, a normative function value ρ ( n) _{Based on the MMMC} and the reference value ρ (n) _MMMC ⁽⁰⁾ , the partial differential coefficient δρ (n) _MMMC / δx _m of the reference function is calculated using Equation (21). The order of executing steps S38 and S39 and steps S40 and S41 may be reversed or simultaneous. In step S42, in order to restore the m-th component of the reactance vector changed in step S36, a control voltage signal corresponding to the reactance vector in which only the m-th component is changed by the reactance value −Δx _m is Output to variable reactance elements 12-1 to 12-6 and set. If it is determined in step S43 that the partial differential coefficients of the normative function have been calculated for all components of the reactance vector, the process proceeds to step S44, and if not, the process returns to step S35.

In the following steps, by referring to the norm of the gradient vector having the partial differential coefficient calculated in steps S39 and S41 as a component, by selecting a normative function that makes the norm larger, the next step of the reactance vector Calculate the set value. In step S44 of FIG. 8, the norm ‖∇ρ (n) _M2M4の of the gradient vector of the M2M4 normative function whose component is the partial differential coefficient calculated in step S39 and the partial differential coefficient calculated in step S41 are components. The norm 勾 配 ρ (n) of the gradient vector of the reference function of _MMMC is compared with _{MMMC と す る} . Norm ‖∇Ro of the gradient vector of the criterion function of _{M2M4 (n)} M2M4 ‖ is, when greater than the norm ‖∇ρ _{(n) MMMC} ‖ the gradient vector of the criterion function of MMMC, the process proceeds to step S45, the M2M4 The next reactance vector x (n + 1) is calculated based on the gradient vector ρ (n) _M2M4 of the reference function. Otherwise, the process proceeds to step S46, and the next reactance vector x (n + 1) is calculated based on the gradient vector ρ (n) _MMMC of the MMMC normative function. Here, μ in the equations shown in steps S45 and S46 in FIG. 8 is a positive constant that controls the convergence speed of the steepest gradient method (see Non-Patent Document 2). In step S45 or S46, a control voltage signal corresponding to the calculated reactance vector x (n + 1) is further output and set to each variable reactance element 12-1 to 12-6. Next, in step S47, the number of iterations n is incremented by 1. In step S48, it is determined whether or not the number of iterations n has reached a preset maximum number of iterations N. If n <N, step S31 is determined. Returning to FIG. 5, if n ≧ N, the process is terminated.

There are two other parameters that control the algorithm of this adaptive control process: the number of iterations N _SNR and the SNR threshold.

  FIG. 9 shows a flowchart of a subroutine related to the second adaptive control process S27 by the sequential random search method. Steps S3 to S17 are the same as the respective steps shown in FIG. 3. When it is determined in step S17 that the number of iterations n has reached a predetermined maximum value N, the processing is terminated.

In this embodiment, if the SNR value is higher than a predetermined threshold after N iterations, the adaptive control process is consequently as efficient as in the case of the sequential random search method using normative function diversity. become. On the other hand, if the SNR value is still below the threshold after repeating the process N _SNR times, it is determined that blind adaptive beamforming by the steepest gradient method is superior to the sequential random search method, Based on this, after step S25, the process is sequentially switched from the second adaptive control process by the random search method to the first adaptive control process by the steepest gradient method.

  In this embodiment, in order to realize normative function diversity, two normative functions of M2M4 and MMMC are used. However, adaptive control processing may be executed using three or more normative functions. These normative functions are preferably different from one another in convergence speed, stability, and / or other characteristics. Further, in order to realize algorithm diversity, an algorithm different from the sequential random search method and the steepest gradient method may be used. Further, in order to calculate the SNR value in step S24, by referring to the normative function flag CF, a set of the M2M4 normative function of Expression (9) and the calculating function of Expression (16), and the MMMC of Expression (10) Although either the normative function or the set of calculation functions of Expression (12) is selected and used, the SNR value may be calculated always using any one of the sets.

  As described above, according to the array antenna control method and control apparatus of the present embodiment, the problem of the tradeoff between the convergence speed and the stability is solved, and compared with the prior art, the processing is simpler. Calculate the reactance value of the variable reactance element to converge the pattern of the electronically controlled waveguide array antenna device at high speed and stably, and to direct the main beam of the array antenna toward the desired wave and the null toward the interference wave. Can be set.

  Hereinafter, simulation results indicating the performance of the array antenna control apparatus according to the embodiment of the present invention will be described.

  FIG. 10 shows simulation results according to the first embodiment of the present invention. Each azimuth angle with respect to a gain in the azimuth angle 0 degree direction when using normative function diversity and without using normative function diversity is shown. It is a directivity pattern which shows the relative gain in a direction. The algorithm is a sequential random search method. The initial value of SNR is 10 dB, the arrival angle of the desired wave signal is 0 degree, and the arrival angle of the interference wave signal is 45 degrees. As can be seen from this pattern, normative function diversity improves blind adaptive beamforming for sequential random search methods. In addition, according to the simulation result of Non-Patent Document 3, it is shown that when a random vector R (n) having a different distribution is used, the Gaussian distribution gives a better result than the uniform distribution. .

  FIG. 11 is a simulation result according to the first embodiment of the present invention, in which the array antenna control apparatus with respect to the number of iterations n in the case of using normative function diversity and in the case of not using normative function diversity. It is a graph which shows output SIR. The algorithm is a sequential random search method. The initial value of SNR is 10 dB, the arrival angle of the desired wave signal is 0 degree, and the arrival angle of the interference wave signal is 45 degrees. In practice, this compares the output SIR with an average value of 1000 iterations up to the 50th iteration of the sequential random search method. The convergence curve of this graph shows that the adaptive control processing by the sequential random search method using the reference function diversity is more effective than the algorithm using only one reference function of M2M4 or MMMC.

  Furthermore, a simulation was performed for the purpose of evaluating the performance of adaptive control processing using algorithm diversity and normative function diversity according to the second embodiment of the present invention. The directivity pattern simulation of the array antenna apparatus 100 was performed when there were several angles of arrival (DOA) and the initial values of SNR were different (0 to 20 dB). In the simulation, a desired wave signal is incident on the array antenna device 100, and an interference wave signal is also added.

  FIG. 12 shows simulation results according to the second embodiment of the present invention. In each azimuth angle direction with respect to a gain in the azimuth angle 0 degree direction when algorithm diversity is used and when algorithm diversity is not used, FIG. It is a directivity pattern showing the relative gain of. The simulation is based on adaptive control processing according to the second embodiment using algorithm diversity and reference function diversity, and adaptive control according to the first embodiment using a sequential random search method using reference function diversity (that is, algorithm diversity is not used). It was executed for the processing and the adaptive control processing of the prior art of Non-Patent Document 6 by the steepest gradient method using the normative function diversity of M2M4 and MMMC (that is, not using algorithm diversity). The simulation results show that, regardless of the SNR value, blind adaptive beamforming by adaptive control processing using algorithm diversity and reference function diversity is the steepest gradient method or sequential random search method using reference function diversity. Showed that it was better than either. FIG. 12 shows a simulation result when the initial value of the SNR is 10 dB, the arrival angle of the desired wave signal is 0 degree, and the arrival angle of the interference wave signal is 45 degrees.

FIG. 13 is a simulation result according to the second embodiment of the present invention, and shows the output SIR of the array antenna controller with respect to the number of iterations n when algorithm diversity is used and when algorithm diversity is not used. It is a graph which shows. The convergence curve of this graph is for comparing the simultaneous diversity of the norm and the algorithm with respect to the steepest gradient method using the norm function diversity and the sequential random search method. The initial value of the SNR was 10 dB, the arrival angle of the desired wave signal was 0 degree, and the arrival angle of the interference wave signal was 45 degrees. This simulation was performed with 1000 iterations up to N = 50. The number of iterations N _SNR that is a parameter of step S22 is set to 25. The results of FIG. 13 show that during the first N _SNR iterations, the convergence curve of the adaptive control process using algorithm diversity and reference function diversity and the convergence of the adaptive control process by the sequential random search method using reference function diversity are shown. It shows that the curve is almost the same. In practice, however, the steepest gradient method (step S26) is used instead of the sequential random search method (step S27) each time the SNR value falls below the threshold parameter for the samples in the N _SNR iterations in the trial. The

  Since the threshold value in step S25 in FIG. 5 is set to 10 dB, among samples measured by the adaptive control process using algorithm diversity and normative function diversity, processing is sequentially performed from the random search method to the steepest gradient. There is something to switch to the law. In this case, each parameter used to calculate the reactance vector is initialized. In the graph of FIG. 13, it appears that the SIR output value related to the adaptive control processing using algorithm diversity and normative function diversity drops, and then converges rapidly to reach the SIR output value of the steepest gradient algorithm. This is why.

  Eventually, the adaptive control process using algorithm diversity and normative function diversity has the same efficiency as the adaptive control process by the steepest gradient method using normative function diversity. In this simulation, the convergence curve of the steepest gradient method is sequentially superior to the convergence curve of the random search method. However, since the sequential random search method is not as complicated as the steepest gradient method, the adaptive control processing using algorithm diversity and normative function diversity is not as complicated as the adaptive control processing by the steepest gradient method. Such an algorithm of the second embodiment is more efficient than others.

  In the above preferred embodiment, the norm function is a norm function for obtaining the reactance value for adaptive control, and the optimum solution of the reactance vector is calculated so as to maximize it. Not limited to this, the reciprocal of the normative function may be a normative function for obtaining a reactance value for adaptive control, and the optimum solution of the reactance vector may be calculated so as to minimize it.

  In the above preferred embodiment, the initial adaptive control process by the sequential random search method is executed in step S21 of FIG. 5 and the second adaptive control process by the sequential random search method is executed in step S27 of FIG. However, the present invention is not limited to this, and in these initial adaptive control processing and second adaptive control processing, iterative numerical methods in nonlinear programming methods such as the following simple random method or high-dimensional bisection method may be used. Good.

In the simple random search method, the following procedure is used.
(I) First, processing is started by a predetermined initial value x (1) of a reactance vector (for example, a reactance vector when the ESPAR antenna device 100 is set to an omni antenna).
(Ii) Next, using this initial value, a value added to the initial value is calculated by generating a random number within a predetermined existence range.
(Iii) The estimated value in the reactance vector is calculated by adding the calculated addition value to the initial value.
(Iv) If the normative function value in the calculated estimated value is equal to or greater than a predetermined threshold value (for example, 0.9), the estimated value is set as a reactance vector to be set. ) And repeat the process.

In the high-dimensional bisection method, the following procedure is used.
(I) First, the iteration number parameter n (that is, the nth iteration) is set to 1, and the process is started.
(Ii) Next, a predetermined existence range of each reactance value of the reactance vector (in the second and subsequent times, the existence range of the estimated value selected before) is equally divided into two, and an average value of each of the two existence ranges divided into two (Two average values for each variable reactance element 12-1 to 12-6) is calculated.
(Iii) The normative function value for the two average values is calculated, and the one with the larger normative function value is set as the next estimated value in the reactance vector.
(Iv) The iteration number parameter n is incremented by 1, and the process returns to step (ii) to repeat the process. This iterative process is executed until the normative function value becomes a predetermined threshold value (for example, 0.9) or more.

  The present invention presents a new solution for the deployment of smart antennas for wireless communication systems. First, it has been shown that normative function diversity results in adaptive control algorithms that form directional patterns faster and converge more stably. However, the efficiency of both the steepest gradient method and the sequential random search method depends on the condition of the SNR value of the received signal power. Thus, using algorithm diversity and reference function diversity provides an improvement in blind adaptive beamforming for electronically controlled waveguide array antenna devices.

It is a block diagram which shows the structure of the control apparatus of the array antenna which concerns on the 1st Embodiment of this invention. It is sectional drawing which shows the detailed structure of the array antenna apparatus 100 which concerns on this embodiment. It is a 1st part of the flowchart which shows the adaptive control process by the sequential random search method using normative function diversity which the adaptive control type controller 20 of FIG. 1 performs. It is a 2nd part of the flowchart which shows the adaptive control process by the sequential random search method using normative function diversity which the adaptive control type | mold controller 20 of FIG. 1 performs. It is a flowchart which shows the adaptive control process using the algorithm diversity and normative function diversity which the adaptive control type controller 20 performs in the control apparatus of the array antenna which concerns on the 2nd Embodiment of this invention. It is a flowchart which shows the subroutine which concerns on the initial adaptive control process S21 by the sequential random search method of FIG. FIG. 6A is a first part of a flowchart showing a subroutine related to the first adaptive control process S <b> 26 by the steepest gradient method of FIG. 5. FIG. 6B is a second part of a flowchart showing a subroutine related to the first adaptive control process S <b> 26 by the steepest gradient method of FIG. 5. It is a flowchart which shows the subroutine which concerns on 2nd adaptive control processing S27 by the sequential random search method of FIG. It is a simulation result which concerns on the 1st Embodiment of this invention, Comprising: Relative in each azimuth direction with respect to the gain of an azimuth | direction azimuth | direction direction in the case where a norm function diversity is used and when a norm function diversity is not used It is a directivity pattern indicating gain. It is a simulation result which concerns on the 1st Embodiment of this invention, Comprising: The output SIR of the control apparatus of the array antenna with respect to the frequency | count of repetition n in each of the case where reference function diversity is used and the case where reference function diversity is not used is shown It is a graph. It is a simulation result which concerns on the 2nd Embodiment of this invention, Comprising: The relative gain in each azimuth angle direction with respect to the gain of an azimuth angle 0 degree direction in each case where algorithm diversity is used and algorithm diversity is not used It is the directivity pattern shown. It is a simulation result which concerns on the 2nd Embodiment of this invention, Comprising: It is a graph which shows the output SIR of the control apparatus of an array antenna with respect to the frequency | count of repetition n in each of the case where algorithm diversity is used, and the case where algorithm diversity is not used. is there.

Explanation of symbols

A0: Excitation element,
A1 to A6 ... non-excited elements,
1 ... Low noise amplifier (LNA),
2. Down converter (D / C),
3 ... A / D converter,
4 ... demodulator,
5 ... Coaxial cable,
11: Ground conductor,
12-1 to 12-6 ... variable reactance element,
13 ... Reactance value table memory,
20 ... Adaptive control type controller,
100: Array antenna device.

Claims (5)

An excitation element for receiving a radio signal, at least one non-excitation element provided at a predetermined distance from the excitation element, and a variable reactance element connected to each of the non-excitation elements, By changing the reactance value of each variable reactance element, each non-excited element is operated as a director or a reflector, respectively, and the array antenna control apparatus changes the directivity characteristics of the array antenna.
When the reactance value of each variable reactance element is set by random perturbation from a predetermined set value, the two norms before and after the perturbation are used, using two normative functions related to the radio signal received by the array antenna. Each of the values of the function is calculated and, for at least one of the two normative functions, the normative function value after the perturbation increases relative to the normative function value before the perturbation, the perturbation of the perturbation Each subsequent reactance value is set as a new set value for each reactance value of each variable reactance element, while the normative function value after the perturbation is the norm before the perturbation for both of the two normative functions. Calculation to set each reactance value before the perturbation as a set value of each reactance value of each variable reactance element when the function value is below And a constant means,
Control means for repeatedly executing the processing of the calculation setting means,
Thus, the array antenna control apparatus calculates and sets the reactance value of the variable reactance element for directing the main beam of the array antenna in the direction of the desired wave and directing the null in the direction of the interference wave. An excitation element for receiving a radio signal, at least one non-excitation element provided at a predetermined distance from the excitation element, and a variable reactance element connected to each of the non-excitation elements, By changing the reactance value of each variable reactance element, each non-excited element operates as a director or a reflector, respectively, and the array antenna control apparatus changes the directivity characteristics of the array antenna.
When the reactance value of each variable reactance element is set by random perturbation from a predetermined set value, the two norms before and after the perturbation are used, using two normative functions related to the radio signal received by the array antenna. Each of the values of the function is calculated and, for at least one of the two normative functions, the normative function value after the perturbation increases relative to the normative function value before the perturbation, the perturbation of the perturbation Each subsequent reactance value is set as a new set value for each reactance value of each variable reactance element, while the normative function value after the perturbation is the norm before the perturbation for both of the two normative functions. Calculation to set each reactance value before the perturbation as a set value of each reactance value of each variable reactance element when the function value is below And a constant means,
First control means for repeatedly executing the processing of the calculation setting means a predetermined number of times;
After executing the processing of the second means, based on a radio signal received by the array antenna, a predetermined signal-to-noise ratio calculation function including one of the two reference functions is used. Calculating means for calculating a signal-to-noise ratio of the received radio signal;
When the calculated signal-to-noise ratio is lower than a predetermined threshold value, the reactance values of the variable reactance elements are sequentially perturbed by a predetermined shift amount, and the reactance values are calculated based on the radio signals received by the array antenna. The gradient vector of each normative function relating to the value is calculated, and the value of the normative function corresponding to the gradient vector having the maximum norm is calculated based on the gradient vector having the maximum norm among the calculated gradient vectors. Updating means for repeatedly executing the reactance value of each of the variable reactance elements by the steepest gradient method so as to be maximized,
Second control means for repeatedly executing the processing of the calculation setting means when the calculated signal-to-noise ratio is equal to or greater than the threshold value;
Thus, the array antenna control apparatus calculates and sets the reactance value of the variable reactance element for directing the main beam of the array antenna in the direction of the desired wave and directing the null in the direction of the interference wave. An excitation element for receiving a radio signal, at least one non-excitation element provided at a predetermined distance from the excitation element, and a variable reactance element connected to each of the non-excitation elements, By changing the reactance value of each variable reactance element, each non-excited element operates as a director or a reflector, respectively, and the array antenna control apparatus changes the directivity characteristics of the array antenna.
When the reactance value of each variable reactance element is set by random perturbation from a predetermined set value, the two norms before and after the perturbation are used, using two normative functions related to the radio signal received by the array antenna. Each of the values of the function is calculated and, for at least one of the two normative functions, the normative function value after the perturbation increases relative to the normative function value before the perturbation, the perturbation of the perturbation Calculation setting means for setting each subsequent reactance value as a new set value of each reactance value of each variable reactance element;
First control means for repeatedly executing the processing of the calculation setting means a predetermined number of times;
After executing the processing of the second means, based on a radio signal received by the array antenna, a predetermined signal-to-noise ratio calculation function including one of the two reference functions is used. Calculating means for calculating a signal-to-noise ratio of the received radio signal;
When the calculated signal-to-noise ratio is lower than a predetermined threshold value, the reactance values of the variable reactance elements are sequentially perturbed by a predetermined shift amount, and the reactance values are calculated based on the radio signals received by the array antenna. The gradient vector of each normative function relating to the value is calculated, and the value of the normative function corresponding to the gradient vector having the maximum norm is calculated based on the gradient vector having the maximum norm among the calculated gradient vectors. Updating means for repeatedly executing the reactance value of each variable reactance element by the steepest gradient method so as to maximize
Second control means for repeatedly executing the processing of the calculation setting means when the calculated signal-to-noise ratio is equal to or greater than the threshold value;
Thus, the array antenna control apparatus calculates and sets the reactance value of the variable reactance element for directing the main beam of the array antenna in the direction of the desired wave and directing the null in the direction of the interference wave. An excitation element for receiving a radio signal, at least one non-excitation element provided at a predetermined distance from the excitation element, and a variable reactance element connected to each of the non-excitation elements, By changing the reactance value of each variable reactance element, each non-excited element operates as a director or a reflector, respectively, and the array antenna control apparatus changes the directivity characteristics of the array antenna.
The range of reactance values that can be taken by each of the variable reactance elements is divided into two, and when the median value of each range after two minutes is set, the two normative functions related to the radio signal received by the array antenna are used. The value of each normative function corresponding to the median value of each range after bisection is calculated, and the normative function value corresponding to the median value of each range after dichotomy for at least one of the two normative functions Calculation setting means for setting each reactance value corresponding to a more increasing normative function value as a new set value of each reactance value of each variable reactance element;
First control means for repeatedly executing the processing of the calculation setting means a predetermined number of times;
After executing the processing of the second means, based on a radio signal received by the array antenna, a predetermined signal-to-noise ratio calculation function including one of the two reference functions is used. Calculating means for calculating a signal-to-noise ratio of the received radio signal;
When the calculated signal-to-noise ratio is lower than a predetermined threshold value, the reactance values of the variable reactance elements are sequentially perturbed by a predetermined shift amount, and the reactance values are calculated based on the radio signals received by the array antenna. The gradient vector of each normative function relating to the value is calculated, and the value of the normative function corresponding to the gradient vector having the maximum norm is calculated based on the gradient vector having the maximum norm among the calculated gradient vectors. Updating means for repeatedly executing the reactance value of each variable reactance element by the steepest gradient method so as to maximize
Second control means for repeatedly executing the processing of the calculation setting means when the calculated signal-to-noise ratio is equal to or greater than the threshold value;
Thus, the array antenna control apparatus calculates and sets the reactance value of the variable reactance element for directing the main beam of the array antenna in the direction of the desired wave and directing the null in the direction of the interference wave. The above two normative functions are
A first normative function formed by dividing an average value of the fourth power value of the received radio signal in a predetermined period by a square value of the average value of the square value of the received radio signal;
M is an integer greater than or equal to 2, and the square value of the absolute value of the average value of the M power values of the received radio signal in a predetermined period is the square value of the absolute value of the M power value of the received radio signal. 5. The array antenna control apparatus according to claim 1, further comprising a second reference function obtained by dividing the average value of the second reference function.

Images