JP6166641B2 - Weight coefficient calculation apparatus, adaptive array reception apparatus, and weight coefficient calculation method - Google Patents

Description

  The present invention relates to a weighting factor calculating device, an adaptive array receiving device, and a weighting factor calculating method.

  In order to cope with various large-capacity services accompanying the recent spread of optical access and the like, it is required to improve the transmission speed of wireless communication. Since the occupied frequency band is proportional to the transmission speed, this can be realized by expanding the frequency band. However, since the actual frequency resources are limited, there is a limit to the expansion of the frequency band. In addition, various wireless access systems such as WiFi (registered trademark), WiMAX (registered trademark), and LTE (registered trademark) are widespread, and in particular, frequency resources in the microwave band allocated to these systems. Is in a tight situation.

  Therefore, in order to improve the transmission capacity under a limited frequency resource environment, the transmission / reception station is provided with a plurality of antennas, and the application of MIMO (Multiple-Input Multiple-Output) or multi-user MIMO (MU-MIMO) technology. The space division multiplex transmission by is effective. By extending this method, arranging centralized control stations that share or collectively handle propagation path (channel) information, transmission signals and reception signals among a plurality of base stations, and apply (MU-) MIMO technology, It is also effective to cooperate with base stations that can eliminate interference between base stations. These technologies make it possible to directly calculate weighting factors (weights) that suppress co-channel interference by grasping channel information between all antennas (including interference sources) in advance. To do. However, in order to estimate the channel information, reference signals (training signals) that are known to each other between transmission and reception are required, and generally the overhead due to the reference signals increases in proportion to the number of antennas.

  On the other hand, an adaptive array antenna is effective as a technique that enables interference suppression without requiring prior information about a received interference signal (see Non-Patent Document 1 and Non-Patent Document 2). There are various algorithms for calculating the weighting factor, and among them, power inversion adaptive array (PIAA), eigen-vector beam adaptive array (EBAA), eigen-vector beam adaptive array (EBAA), and so on. A constant envelope algorithm (CMA) is a blind-type weight coefficient calculation algorithm that enables interference suppression without requiring prior information such as a reference signal.

  In space division multiplex transmission using an adaptive array antenna, the blind weight coefficient calculation algorithm is more effective as the number of antennas increases because there is no overhead due to prior information such as a reference signal. The power inversion adaptive array (PIAA) and the eigenbeam space adaptive array (EBAA) can be implemented with relatively simple operations, and can be performed from the correlation matrix of the received signal without iterative processing. The weighting factor can be calculated directly. On the other hand, the constant envelope algorithm (CMA) involves iterative processing, captures the largest received signal, and can sufficiently suppress other received signals.

Nobuyoshi Kikuma, “Adaptive Antenna Technology”, Ohm, October 2003 Hatanaka, Karasawa, “A software antenna that is resistant to suddenly generated strong interference waves-using the power inversion characteristics of the second eigenvalue of the array antenna correlation matrix,” IEICE Transactions. B, Communication J85- B (7), 1086-1094, 2002-07-01

  However, in the power inversion adaptive array (PIAA) and the eigenbeam space adaptive array (EBAA), the scheme using the eigenvector corresponding to the minimum eigenvalue is a signal-to-interference ratio (SIR). When the (Interference Ratio) is a positive value, the smaller the power ratio between the desired signal and the interference signal (the power ratio of the received signal) is, the more the received desired signal is suppressed, so the interference suppression effect is limited. . On the other hand, in the constant envelope algorithm (CMA), when the signal-to-interference ratio is a negative value (when the power of the interference signal is larger than that of the desired signal), the received desired signal is suppressed. Cannot be obtained. As described above, the weight coefficient calculation apparatus has a problem that a large interference suppression effect cannot be obtained.

  The present invention has been made in view of the above points, and an object of the present invention is to provide a weighting factor calculation device, an adaptive array receiving device, and a weighting factor calculation method capable of obtaining a large interference suppression effect.

  One aspect of the present invention provides a first weighting factor calculation unit that calculates a first weighting factor based on a received signal including a received desired signal and an interference signal, and the received signal using the first weighting factor as an initial value. And a second weighting factor calculating unit that calculates a second weighting factor to be applied to the weighting factor calculating device.

  In one aspect of the present invention, the first weighting factor calculation unit calculates the first weighting factor by a first algorithm, and the second weighting factor calculation unit calculates the second weighting factor by a second algorithm. It is a weighting factor calculation device characterized by calculating.

  In one aspect of the present invention, the first weighting factor calculation unit calculates the first weighting factor by a power inversion adaptive array or an eigenbeam space adaptive array as the first algorithm, The weighting factor calculation device is characterized in that the second weighting factor calculation unit calculates the second weighting factor by a constant envelope algorithm as the second algorithm.

  According to an aspect of the present invention, when the first weighting factor calculation unit calculates the first weighting factor by the eigenbeam space adaptive array, the first weighting factor is based on reception quality of the received signal. Is a weighting factor calculation device characterized by selecting an eigenvector.

  In one aspect of the present invention, the first weighting factor calculation unit determines whether or not the reception quality of the reception signal satisfies a predetermined condition, and the reception quality of the reception signal is the predetermined condition. If the above condition is not satisfied, the processing for calculating the first weighting coefficient is stopped.

  In one aspect of the present invention, the first weighting factor calculation unit determines whether or not the reception quality of the reception signal satisfies a predetermined condition, and the reception quality of the reception signal is the predetermined condition. Is satisfied, the first weighting factor is output as the initial value to the second weighting factor calculating unit, and when the reception quality of the received signal does not satisfy the predetermined condition, the predetermined factor is A weighting factor calculating apparatus that outputs the initial value to the second weighting factor calculating unit.

  According to one aspect of the present invention, a radio unit that performs reception processing on a received radio frequency signal including a desired signal and an interference signal, and generates a reception signal including the desired signal and the interference signal, and the received signal A first weighting factor calculating unit that calculates a first weighting factor; a second weighting factor calculating unit that calculates a second weighting factor to be applied to the received signal using the first weighting factor as an initial value; A multiplier that multiplies the second weighting factor; an adder that adds the reception signal multiplied by the second weighting factor for all the radio units; and a demodulator that performs a demodulation process on the added reception signal And an adaptive array receiving apparatus.

  One aspect of the present invention is a weighting factor calculation method in a weighting factor calculation device, in which a first weighting factor calculation unit calculates a first weighting factor based on a received signal including a received desired signal and an interference signal. And a step of calculating a second weighting coefficient to be applied to the received signal using the first weighting coefficient as an initial value. .

  According to the present invention, the first weighting factor calculation unit calculates the first weighting factor based on the received signal including the received desired signal and interference signal. The second weighting factor calculation unit calculates a second weighting factor to be applied to the received signal using the first weighting factor as an initial value. Thereby, the weighting factor calculation device, the adaptive array receiving device, and the weighting factor calculation method can obtain a large interference suppression effect.

It is a block diagram which shows the structural example of the adaptive array receiver in 1st Embodiment of this invention. It is a flowchart which shows the example of the operation | movement procedure of the adaptive array receiver in 1st Embodiment of this invention. It is a figure which shows the example of the directivity pattern in 1st Embodiment of this invention. It is a figure which shows the example of the convergence speed of an evaluation function in 1st Embodiment of this invention. It is a flowchart which shows the example of the operation | movement procedure of the adaptive array receiver in 2nd Embodiment of this invention. It is a flowchart which shows the example of the operation | movement procedure of the adaptive array receiver in 3rd Embodiment of this invention.

[First Embodiment]
A first embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram illustrating a configuration example of an adaptive array receiver. The adaptive array receiver 100 includes an antenna 110, a radio unit 120, a weighting factor calculator 130, a multiplier 140, an adder 150, and a demodulator 160.

  The adaptive array receiver 100 includes antennas 110-1 to 110-K (K is an integer equal to or greater than 1). That is, a plurality of antennas 110 may be provided. Hereinafter, items common to the antennas 110-1 to 110 -K are denoted by “antenna 110” by omitting reference numerals. The antenna 110 receives a radio frequency (RF) signal including a desired signal via the first channel and an interference signal via the second channel.

  The radio unit 120 is provided for each antenna 110. That is, adaptive array receiving apparatus 100 includes radio units 120-1 to 120-K. Hereinafter, items common to the radio units 120-1 to 120-K are denoted by “radio unit 120” by omitting reference numerals.

  The radio unit 120-k (k is any one of symbols 1 to K) performs reception processing on the radio frequency signal received by the antenna 110-k, thereby converting the radio frequency signal into a received signal (baseband signal). Convert. Here, the reception processing includes, for example, filter processing for removing out-of-band frequency components, analog / digital (A / D) conversion processing, and the like. Radio section 120 outputs the received signal converted from the radio frequency signal to weighting factor calculation apparatus 130.

  The weighting factor calculation device 130 includes a first weighting factor calculation unit 131 and a second weighting factor calculation unit 132. The first weight coefficient calculation unit 131 calculates a first weight coefficient. The first weighting factor is a weighting factor used as an initial value when calculating the second weighting factor applied to the reception signal converted from the radio frequency signal.

Received signal vector X including a desired signal and an interference signal is input to first weighting factor calculation unit 131 from radio units 120-1 to 120-K. An autocorrelation matrix R _xx obtained from the received signal vector X is expressed by Expression (1).

The first weight coefficient calculation unit 131 may calculate the first weight coefficient by a power inversion adaptive array (PIAA) as an example of a calculation process that does not involve repetition. The first weighting factor W _PIAA calculated by the power inversion adaptive array (PIAA) is expressed by Equation (2) and Equation (3) using R _xx .

  Here, S represents a steering vector. The power inversion adaptive array has the property of inverting the power ratio between the desired signal and the interference signal (power inversion), and is therefore an effective algorithm when the desired signal is smaller than the interference signal.

The first weighting factor calculation unit 131 may calculate the first weighting factor by an eigen beam space adaptive array (EBAA) as an example of a calculation process without repetition. The eigenbeam space adaptive array is an algorithm that _obtains an eigenvector v _k (k = 1,..., K) of the autocorrelation matrix R _xx and selects one of the eigenvectors v _k as the first weighting coefficient _WEBAA. is there. The autocorrelation matrix R _xx is expressed by Equation (4). The eigenvalue Λ is expressed by equation (5). The eigenvector V is expressed by equation (6). Here, the relationship represented by Expression (7) is established.

When the number of antennas K is larger than the number of incoming waves L (K> L), that is, when there is a margin in the degree of freedom of antennas, the eigenvectors v _{1 to} v _L are effective as the first weighting factors. In addition, when incoming waves are arranged in order of increasing power level, the first weight coefficient _WEBAA for obtaining a desired signal having the k-th largest power level is k-th as represented by Equation (8). Of the eigenvector v _k .

The first weight coefficient calculation unit 131, if the desired signal is greater than the interference signal (when the signal-to-interference ratio is a positive value), by selecting the eigenvector v ₁ as a first weighting factor, a beam in a desired signal Therefore, it is possible to obtain the first weighting coefficient that obtains the same effect as that of the maximum ratio combining (MRC). On the other hand, when the desired signal is smaller than the interference signal (when the signal-to-interference ratio is a negative value), the first weight coefficient calculation unit 131 selects the eigenvector v _L as the first weight coefficient, A first weighting factor having the property of inverting the power ratio with the interference signal in the same manner as the power inversion adaptive array can be obtained. The first weighting factor calculation unit 131 outputs the calculated first weighting factor to the second weighting factor calculation unit 132.

A received signal vector X including a desired signal and an interference signal and a first weight coefficient are input from the first weight coefficient calculator 131 to the second weight coefficient calculator 132. The second weighting factor calculation unit 132 calculates a second weighting factor to be applied to the received signal converted from the radio frequency signal by a constant envelope algorithm (CMA) as an example of a calculation process involving repetition. Here, the second weighting factor calculation unit 132 calculates the second weighting factor using the first weighting factor calculated by the first weighting factor calculation unit 131 as an initial value. The evaluation function Q (W _CMA (m)) for optimizing the second weighting coefficient is expressed by Expression (9) and Expression (10).

Here, W _CMA (m) represents a second weighting coefficient to be applied (multiplied) to the received signal vector X. m represents the number of repetitions. y represents the output from the multiplier 140 (array output). σ represents a desired envelope value. E represents an expected value. H represents the complex conjugate transpose of the matrix. p and q are values of 1 or 2, respectively.

When the desired signal has constant envelope characteristics, the constant envelope algorithm (CMA) sets the second weighting factor so as to minimize the evaluation function Q (W _CMA (m)) using the characteristic. Update repeatedly. There are several algorithms for optimizing the weighting factor by CMA. Here, as an example, an example of optimization by LS (Least-Squares) -CMA will be described.

  The second weighting coefficient is updated based on Expressions (11) to (13) when p = 1 and q = 2. Here, * represents a complex conjugate. i (i = 1,..., n) represents an index indicating the sample number of each signal.

The second weighting factor calculation unit 132 holds the received signal of n samples at a certain time, and repeats the update based on the equations (11) to (13) by a predetermined number of repetitions m times. Then, an optimized second weighting factor W _CMA (m) is calculated. Here, the initial value W _CMA (1) when calculating the second weighting factor W _CMA (m) is the first weighting factor calculated by the first weighting factor calculating unit 131. When the first weighting factor is not calculated, the initial value W _CMA (1) for calculating the second weighting factor W _CMA (m) is a predetermined value, for example, Equation (14) The value represented by may be sufficient.

  A multiplier 140 is provided for each antenna 110. That is, adaptive array receiving apparatus 100 includes multipliers 140-1 to 140-K. Hereinafter, items common to the multipliers 140-1 to 140 -K are denoted by “multiplier 140” by omitting symbols.

  The multiplier 140 receives the optimized second weight coefficient from the second weight coefficient calculator 132. Multiplier 140-k multiplies the received signal including the desired signal and interference signal output from radio section 120-k by the second weighting factor, and adds the received signal multiplied by the second weighting factor to adder 150. Output.

Adder 150 adds the received signal multiplied by the second weighting coefficient to radio sections 120-1 to 120 K (array signal processing), and outputs the added received signal to demodulation section 160.
Demodulation section 160 performs demodulation processing on the reception signal added by adder 150. Here, the demodulator 160 may extract the demapped symbol from the added received signal by performing orthogonal demodulation processing on the added received signal. Demodulation section 160 outputs a final data series by performing error correction decoding processing or the like on the extracted symbols.

  In addition, the process which calculates a 1st weighting coefficient and a 2nd weighting coefficient may be performed with a predetermined period. The time required to obtain the optimal second weighting factor depends on the number n of received signal samples and the number m of repetitions by the constant envelope algorithm. In addition, when the signal-to-noise ratio (SNR) of the received signal is lower than a predetermined value, or in a modulation scheme that takes a large number of multi-values (such as 16QAM), the required number of samples n and The number of repetitions m is relatively large.

FIG. 2 is a flowchart illustrating an example of an operation procedure of the adaptive array receiver.
(Step S1) The radio unit 120 performs reception processing on the radio frequency signal including the desired signal and the interference signal received by the antenna 110, and generates a reception signal including the desired signal and the interference signal. Here, the radio unit 120-k performs reception processing on the radio frequency signal including the desired signal and the interference signal received by the antenna 110-k.

(Step S2) The first weighting factor calculation unit 131 calculates a first weighting factor (for example, a power inversion adaptive array or an eigenbeam space adaptive array).
(Step S3) The second weighting factor calculating unit 132 sets the first weighting factor as an initial value when calculating the second weighting factor.
(Step S4) The second weighting factor calculation unit 132 calculates a second weighting factor (for example, a constant envelope algorithm).

(Step S5) The multiplier 140 multiplies the reception signal generated by the radio unit 120 by the second weighting factor. Here, multiplier 140-k multiplies the received signal generated by radio section 120-k by the second weighting factor.
(Step S6) The adder 150 adds the desired signal and the interference signal multiplied by the second weighting factor to the radio units 120-1 to 120-K (array signal processing).
(Step S7) The demodulator 160 performs demodulation processing on the added received signal.

  FIG. 3 shows an example of a directivity pattern. The horizontal axis indicates the angle [°]. The vertical axis represents output SINR (Signal-to-Interference Noise Ratio) [dB] (= output signal to interference noise ratio). In FIG. 3, the case where the first weighting factor calculation unit 131 executes the power inversion adaptive array and the second weighting factor calculation unit 132 executes the constant envelope algorithm is expressed as “PIAA w / CMA”. Has been. Further, when the first weighting factor calculation unit 131 executes an eigenbeam space adaptive array (first eigenvector) and the second weighting factor calculation unit 132 executes a constant envelope algorithm, “EBAA w / CMA” It is written.

  In FIG. 3, the number of iterations (iterations) of the constant envelope algorithm by the second weight coefficient calculation unit 132 is, for example, 5 times. The signal-to-noise ratio (SNR) is 20 [dB] as an example. In addition, the power ratio (received signal power ratio) indicating the value obtained by dividing the power level of the first wave by the power level of the second wave (= first wave / second wave) is, for example, 3 [dB]. is there.

  When the power ratio indicating the value obtained by dividing the power level of the first wave by the power level of the second wave (power ratio of the received signal) is 3 [dB], the output SINR by the power inversion adaptive array alone is The first wave has an angle of about −3 [dB] in the direction of the angle 0 [°]. Thus, since the difference between the power level of the first wave and the power level of the second wave is small, the interference suppression effect is limited. Further, in the eigenbeam space adaptive array using the first eigenvector, the output SINR of the first wave is improved by the effect of the maximum ratio combining, but the output SINR is increased for the interference wave of the second wave. There is no effect of reducing (directing null), and the interference suppression effect is similarly limited.

  The interference suppression effect by only the constant envelope algorithm is more limited as the number of repetitions (the number of iterations) is smaller. This is because the null directed to the second wave (interference wave in the constant envelope algorithm) to be suppressed and the gain of the first wave (desired wave in the constant envelope algorithm) to be captured are insufficient. That's why.

  On the other hand, as shown in “PIAA w / CMA”, the weight coefficient calculation device 130 can direct a deeper null to the first wave (interference wave in PIAA w / CMA) that is the object of suppression. . Further, as shown in “EBAA w / CMA”, the weight coefficient calculation device 130 directs a deeper null to the second wave (interference wave in EBAA w / CMA) to be suppressed, and captures The gain of the first wave (desired wave in EBAA w / CMA) can be increased.

  FIG. 4 shows an example of the convergence speed of the evaluation function. The horizontal axis indicates the number of repetitions (the number of iterations). The vertical axis represents the value of the evaluation function Q represented by the equation (9). In FIG. 4, the case where the first weighting factor calculation unit 131 executes the power inversion adaptive array and the second weighting factor calculation unit 132 executes the constant envelope algorithm is expressed as “PIAA w / CMA”. Has been. Further, the case where the first weighting factor calculation unit 131 executes the eigenbeam space adaptive array and the second weighting factor calculation unit 132 executes the constant envelope algorithm is described as “EBAA w / CMA”. . In FIG. 4, the signal-to-noise ratio (SNR) is 20 [dB] as an example. Further, a power ratio (= first wave / second wave) indicating a value obtained by dividing the power level of the first wave by the power level of the second wave is 3 [dB] as an example.

  The first weighting factor calculation unit 131 indicates the semi-optimized first weighting factor as “PIAA w / CMA” and “EBAA w / CMA” in order to use them as initial values when calculating the second weighting factor. As can be seen, the convergence of the evaluation function Q can be accelerated as compared with only the constant envelope algorithm. From this, the first weighting coefficient calculation unit 131 can set the number of repetitions of the constant envelope algorithm (the number of iterations) to be small, and the effect of reducing the calculation load and the processing delay can be obtained.

  As described above, the weighting factor calculation apparatus 130 according to the present embodiment includes the first weighting factor calculation unit 131 that calculates the first weighting factor based on the received signal including the received desired signal and interference signal, And a second weighting factor calculating unit 132 that calculates a second weighting factor to be applied to the received signal using the weighting factor as an initial value.

  The adaptive array receiver 100 according to the present embodiment performs reception processing on a received radio frequency signal including a desired signal and an interference signal, and generates radio signals 120-1 to 120 that generate a received signal including the desired signal and the interference signal. -K, a first weighting factor calculation unit 131 that calculates a first weighting factor based on the received signal, and a second weighting factor that calculates a second weighting factor to be applied to the received signal using the first weighting factor as an initial value The calculation unit 132, the multipliers 140-1 to 140-K that multiply the reception signal by the second weighting factor, and the reception signal multiplied by the second weighting factor are all the radio units 120 (radio units 120-1 to 120-1). 120-K), and a demodulator 160 that performs demodulation processing on the added received signal.

  The weighting factor calculation method according to the present embodiment is a weighting factor calculation method in the weighting factor calculation device 130, in which the first weighting factor calculation unit 131 is based on a received signal including a received desired signal and an interference signal. Calculating one weighting factor, determining an initial weighting factor based on the calculated first weighting factor, and a second weighting factor that the second weighting factor calculating unit 132 applies to the received signal using the initial weighting factor as an initial value. Calculating.

  With this configuration, the first weighting factor calculation unit 131 calculates the first weighting factor based on the received desired signal and interference signal. The second weighting factor calculation unit 132 calculates a second weighting factor to be applied to the received signal using the first weighting factor as an initial value.

  In other words, in the adaptive array weighting factor calculation process executed when the radio frequency signal is received, the weighting factor calculation device 130 calculates the semi-optimized first weighting factor and sets the first weighting factor to the initial value. By using the value, the optimized second weighting coefficient is calculated. For example, the weighting factor calculation apparatus 130 uses the first weight obtained by a blind weighting factor calculation algorithm (for example, a power inversion adaptive array or an eigenbeam space adaptive array) that does not involve repetitive processing. The coefficient is set as an initial value when the second weighting coefficient is calculated by a weighting coefficient calculation algorithm (for example, a constant envelope algorithm) that involves repetitive processing.

  Thereby, the weighting factor calculation device 130, the adaptive array receiving device 100, and the weighting factor calculation method can obtain a large interference suppression effect. In addition, the weighting factor calculation device 130, the adaptive array receiving device 100, and the weighting factor calculation method are, for example, the desired signal and the interference signal, regardless of the power ratio between the desired signal and the interference signal (the power ratio of the received signal). Even when the power ratio is small, a large interference suppression effect can be obtained.

  In addition, the weighting factor calculating device 130, the adaptive array receiving device 100, and the weighting factor calculating method can suppress the number of iterations (the number of iterations) when calculating the second weighting factor by the constant envelope algorithm ( For example, refer to FIG. 4), and the necessary calculation amount can be reduced.

The first weighting factor calculation unit 131 may calculate the first weighting factor using a first algorithm. The second weight coefficient calculation unit 132 may calculate the second weight coefficient by the second algorithm.
The first weighting factor calculation unit 131 may calculate the first weighting factor by using a power inversion adaptive array (PIAA) or an eigenbeam space adaptive array (EBAA) as the first algorithm. The second weighting factor calculation unit 132 may calculate the second weighting factor by a constant envelope algorithm (CMA) as the second algorithm.

[Second Embodiment]
The second embodiment is different from the first embodiment in that the first weighting coefficient, which is an initial value when calculating the second weighting coefficient, is determined based on the reception quality of the received signal. In the second embodiment, only differences from the first embodiment will be described.

FIG. 5 is a flowchart illustrating an example of an operation procedure of the adaptive array receiver. Steps Sa1 to Sa7 are the same as steps S1 to S7 shown in FIG.
(Step Sa8) The first weighting factor calculation unit 131 determines whether or not to end the process of calculating the first weighting factor.

  When ending the process of calculating the first weighting coefficient (step Sa8: Yes), the first weighting coefficient calculating unit 131 ends the process of calculating the first weighting coefficient. In addition, the second weight coefficient calculation unit 132 ends the process of calculating the second weight coefficient. For example, when the operation procedure shown in FIG. 5 is repeatedly executed a predetermined number of times, the first weight coefficient calculation unit 131 may end the process of calculating the first weight coefficient. On the other hand, when the process of calculating the first weight coefficient is not terminated (step Sa8: No), the first weight coefficient calculator 131 and the second weight coefficient calculator 132 return the process to step Sa2.

  (Step Sa9) The first weight coefficient calculation unit 131 measures the reception quality of the received signal. Here, the first weighting factor calculation unit 131 may measure the reception quality of the received signal number based on the result of the demodulation processing by the demodulation unit 160, for example.

  (Step Sa10) The first weighting factor calculation unit 131 determines whether or not the reception quality of the received signal satisfies a predetermined condition (for example, whether or not it is equal to or higher than a predetermined threshold). When the reception quality of the received signal satisfies a predetermined condition (step Sa10: Yes), the first weight coefficient calculation unit 131 and the second weight coefficient calculation unit 132 return the process to step Sa2. On the other hand, when the reception quality of the received signal does not satisfy the predetermined condition (step Sa10: No), the first weight coefficient calculation unit 131 and the second weight coefficient calculation unit 132 advance the process to step Sa11.

(Step Sa11) The first weighting factor calculation unit 131 updates the first weighting factor, which is an initial value, to a predetermined value (eg, [1, 0] ^T ). The first weighting factor calculation unit 131 and the second weighting factor calculation unit 132 return the process to step Sa4. Therefore, the first weighting coefficient updated in step Sa11 is used as an initial value when calculating the second weighting coefficient in step Sa4.

  As described above, the first weight coefficient calculation unit 131 determines whether or not the reception quality of the reception signal satisfies a predetermined condition, and when the reception quality of the reception signal does not satisfy the predetermined condition, The process of calculating the first weighting coefficient may be stopped.

  The first weighting factor calculating unit 131 determines whether or not the reception quality of the received signal satisfies a predetermined condition, and if the reception quality of the received signal satisfies the predetermined condition, the first weighting factor calculating unit 131 initializes the first weighting factor. If the reception quality of the received signal does not satisfy a predetermined condition, the predetermined coefficient may be output as an initial value to the second weight coefficient calculation unit 132. Good.

In other words, the first weighting factor calculation unit 131 measures the reception quality of the reception signal after applying the second weighting factor, and if the reception quality of the reception signal does not satisfy the predetermined condition, After updating the weighting factor, the second weighting factor is optimized.
As a result, the weighting factor calculation device 130, the adaptive array receiving device 100, and the weighting factor calculation method can improve followability to channel time variation. More specifically, in the weighting factor calculation device 130, the adaptive array receiving device 100, and the weighting factor calculation method, the power ratio between the desired signal and the interference signal (the power ratio of the received signal) is reversed due to the time variation of the channel. But you can follow this.

[Third Embodiment]
In the third embodiment, as an example, when the first weighting factor is calculated by the eigenbeam space adaptive array, the point that the first weighting factor calculating unit 131 selects the eigenvector based on the reception quality of the received signal. This is different from the first embodiment and the second embodiment. In the third embodiment, only differences from the first embodiment and the second embodiment will be described.

FIG. 6 is a flowchart illustrating an example of an operation procedure of the adaptive array receiver. Step Sb1 is the same as step S1 shown in FIG.
(Step Sb2) The first weighting factor calculation unit 131 calculates a first weighting factor by a blind weighting factor calculation algorithm. Here, as an example, the blind-type weight coefficient calculation algorithm will be described as being an eigenbeam space adaptive array.

  (Step Sb3) The first weighting factor calculation unit 131 selects an eigenvector as the first weighting factor based on the reception quality of the reception signal so that the reception quality of the reception signal satisfies a predetermined condition. For example, the eigenvector to be selected as the optimal first weighting factor that satisfies a predetermined condition cannot be directly determined from the process of calculating the first weighting factor by the eigenbeam space adaptive array. For this reason, the first weight coefficient calculation unit 131 may execute a brute force selection process of selecting another eigenvector if reception quality does not satisfy a predetermined condition, for example.

Steps Sb4 to Sb8 are the same as steps S3 to S7 shown in FIG. Step Sb9 is the same as step Sa8 shown in FIG.
(Step Sb10) The first weighting factor calculator 131 measures the reception quality of the received signal. The first weight coefficient calculation unit 131 returns the process to step Sb3.

  As described above, when calculating the first weighting factor by the eigenbeam space adaptive array (EBAA), the first weighting factor calculating unit 131 uses the eigenvector as the first weighting factor based on the reception quality of the received signal. You may choose.

  As a result, the weighting factor calculation device 130, the adaptive array receiving device 100, and the weighting factor calculation method can improve followability to channel time variation. More specifically, in the weighting factor calculation device 130, the adaptive array receiving device 100, and the weighting factor calculation method, the power ratio between the desired signal and the interference signal (the power ratio of the reception signal) varies due to the channel variation. But you can follow this.

  The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and includes designs and the like that do not depart from the gist of the present invention.

  For example, the calculation algorithm executed by the first weight coefficient calculation unit 131 may not be limited to the power inversion adaptive array (PIAA) and the eigenbeam space adaptive array (EBAA). For example, the calculation algorithm executed by the second weight coefficient calculation unit 132 may not be limited to the constant envelope algorithm (CMA). For example, any other algorithm such as maximum ratio combining (MRC) or minimum mean square error (MMSE) method may be used.

  For example, instead of being applied to a received signal (baseband signal) converted from a radio frequency signal, array signal processing is performed on a center frequency (IF: Intermediate Frequency) band converted from a radio frequency signal that has passed through a filter. It may be applied to the signal. That is, the second weighting factor calculation unit 132 (see FIG. 1) passes, for example, a filter instead of calculating the second weighting factor applied to the reception signal (baseband signal) converted from the radio frequency signal. You may calculate the 2nd weighting coefficient applied to the signal of the center frequency (IF) band converted from the radio frequency signal. In this case, the process of converting the radio frequency signal into the received signal (baseband signal) may be executed by the demodulator 160.

  You may make it implement | achieve the weighting coefficient calculation apparatus and adaptive array receiver in embodiment mentioned above with a computer. In that case, a program for realizing this function may be recorded on a computer-readable recording medium, and the program recorded on this recording medium may be read into a computer system and executed. Here, the “computer system” includes an OS and hardware such as peripheral devices. The “computer-readable recording medium” refers to a storage device such as a flexible medium, a magneto-optical disk, a portable medium such as a ROM and a CD-ROM, and a hard disk incorporated in a computer system. Furthermore, the “computer-readable recording medium” dynamically holds a program for a short time like a communication line when transmitting a program via a network such as the Internet or a communication line such as a telephone line. In this case, a volatile memory inside a computer system serving as a server or a client in that case may be included and a program held for a certain period of time. Further, the program may be a program for realizing a part of the above-described functions, and may be a program capable of realizing the functions described above in combination with a program already recorded in a computer system. It may be realized by using a programmable logic device such as PLD (Programmable Logic Device) or FPGA (Field Programmable Gate Array).

DESCRIPTION OF SYMBOLS 100 ... Adaptive array receiver, 111 ... Antenna, 120 ... Radio | wireless part, 130 ... Weight coefficient calculation apparatus, 131 ... 1st weight coefficient, 132 ... 2nd weight coefficient, 140 ... Multiplier, 150 ... Adder, 160 ... Demodulation vessel

Claims (7)

A first weighting factor calculating unit that calculates a first weighting factor based on a received signal including a received desired signal and an interference signal;
A second weighting factor calculating unit for calculating a second weighting factor to be applied to the received signal, using the first weighting factor as an initial value;
Equipped with a,
The first weighting factor calculation unit determines whether or not the reception quality of the reception signal after applying the second weighting factor satisfies a predetermined condition, and the reception quality of the reception signal is determined in advance. If not satisfied it was criteria, weighting factor calculation apparatus characterized that you stop the process of calculating the first weighting factor. The first weighting factor calculation unit calculates the first weighting factor by a first algorithm,
The weighting factor calculation apparatus according to claim 1, wherein the second weighting factor calculation unit calculates the second weighting factor by a second algorithm. The first weighting factor calculating unit calculates the first weighting factor by a power inversion adaptive array or an eigenbeam space adaptive array as the first algorithm,
The weighting factor calculation apparatus according to claim 2, wherein the second weighting factor calculation unit calculates the second weighting factor by a constant envelope algorithm as the second algorithm.   The first weighting factor calculating unit, when calculating the first weighting factor by the eigenbeam space adaptive array, selects an eigenvector as the first weighting factor based on reception quality of the received signal. The weighting factor calculation apparatus according to claim 3, wherein The first weighting factor calculation unit determines whether or not the reception quality of the reception signal after applying the second weighting factor satisfies a predetermined condition, and the reception quality of the reception signal is determined in advance. If the received condition is satisfied, the first weighting coefficient is output as the initial value to the second weighting coefficient calculating unit, and the reception quality of the received signal does not satisfy the predetermined condition. weighting factor calculating apparatus according to any one of claims 1 to 4 and outputs the coefficients to the second weight coefficient calculation unit as the initial value. A radio unit that performs reception processing on a received radio frequency signal including a desired signal and an interference signal, and generates a reception signal including the desired signal and the interference signal;
A first weighting factor calculator that calculates a first weighting factor based on the received signal;
A second weighting factor calculating unit for calculating a second weighting factor to be applied to the received signal, using the first weighting factor as an initial value;
A multiplier for multiplying the received signal by the second weighting factor;
An adder for adding the received signal multiplied by the second weighting factor for all the radio units;
A demodulator that performs a demodulation process on the added received signal;
Equipped with a,
The first weighting factor calculation unit determines whether or not the reception quality of the reception signal after applying the second weighting factor satisfies a predetermined condition, and the reception quality of the reception signal is determined in advance. If not satisfied was condition, adaptive array reception apparatus characterized that you stop the process of calculating the first weighting factor. A weighting factor calculation method in a weighting factor calculation device,
A first weighting factor calculating unit calculating a first weighting factor based on a received signal including a received desired signal and an interference signal;
A second weighting factor calculating unit calculating a second weighting factor to be applied to the received signal using the first weighting factor as an initial value;
I have a,
In the step of calculating the first weighting factor, the first weighting factor calculating unit determines whether or not reception quality of the reception signal after applying the second weighting factor satisfies a predetermined condition. The weight coefficient calculation method characterized by stopping the process of calculating the first weight coefficient when the reception quality of the received signal does not satisfy the predetermined condition .

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