JP2001285164A - Radio receiver and response victor estimate method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radio receiver and a response vector estimate method that can accurately estimate a response vector without the need for many arithmetic amounts. SOLUTION: A DSP applies adaptive array processing to signals received by antennas ANT1...ANT4 to extract a signal from a desired terminal user. The DSP 10 applies forced phase synchronization processing to the extracted signal corresponding to a prescribed signal reference point. Applying ensemble average processing to a result of complex multiplication between the signal subjected to forced phase synchronization and the signals received by the antennas can estimate a response vector of the terminal user. Furthermore, when it is discriminated that a reception error is caused in demodulation data obtained by applying differential decoding to the signal subjected to forced phase synchronization, the estimate of the response vector is stopped.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a radio receiving apparatus and a response vector estimating method, and more particularly to a radio receiving apparatus and a response for estimating a response vector of a signal received from a mobile terminal apparatus in a base station of a mobile communication system. It relates to a vector estimation method.

[0002]

2. Description of the Related Art In a digital mobile radio communication system such as a cellular phone, which is rapidly developing in recent years, a radio receiver of a base station estimates a response vector of a mobile terminal of each user.

Here, a response vector (response vecto) is used.
r) represents information on the amplitude and phase of the signal from each mobile terminal device among the signal components from the mobile terminal device received by the wireless receiving device of the base station. In the wireless receiving device, by estimating the response vector for each such mobile terminal device, the propagation path characteristics of the wireless section from each mobile terminal device to the base station wireless receiving device, the power value at the time of signal reception, etc. It becomes possible to detect.

In particular, in an adaptive array type radio receiving apparatus which controls the directivity of transmission and reception of signal radio waves by adjusting the amplitude and phase components of signals transmitted and received by a plurality of antennas of a base station, The adjustment of the amplitude and phase components for each is done essentially by calculating a weight vector based on the estimated response vector.

FIG. 13 is a schematic block diagram of a conventional radio receiving apparatus having such a response vector estimating function. First, a method of estimating a response vector in a conventional wireless receiving apparatus will be described with reference to FIG.

The conventional radio receiving apparatus shown in FIG. 13 is, for example, a radio receiving apparatus using two antenna elements 202 and 203.

In FIG. 13, antenna elements 202 and 2
Assuming that the signals received at 03 are X ₁ (t) and X ₂ (t), these received signals are expressed by the following equations.

X ₁ (t) = h ₁₁ S ₁ (t) + h ₁₂ S ₂ (t) + N ₁ (t) (1) X ₂ (t) = h ₂₁ S ₁ (t) + h ₂₂ S ₂ ( t) + N ₂ (t) (2) Here, the signal S ₁ (t) represents a modulation signal transmitted from a mobile terminal device (hereinafter, referred to as a terminal user 1) of the user 1 (not shown). S ₂ (t) is a mobile terminal device of user 2 not shown (hereinafter, referred to as terminal user 2).
It represents the modulated signal transmitted from the coefficients h _11,
h ₂₁ , h ₁₂ and h ₂₂ represent response vectors, and N ₁ (t)
Is the noise component of the signal received by the first antenna element 202, and N ₂ (t) is the second antenna element 203
Is the noise component of the received signal.

More specifically, h ₁₁ is a response vector of the terminal user 1 received by the first antenna element 202, and h ₂₁ is a response vector of the terminal user 1 received by the second antenna element 203 Where h ₁₂ is the response vector of terminal user 2 received by the first antenna element 202 and h ₂₂ is the response vector of terminal user 2 received by the second antenna element 203.

Here, the response vector for each terminal user is obtained by multiplying the received signals X ₁ (t) and X ₂ (t) by S ₁ ^* (t) which is a complex conjugate of the modulation signal of the terminal user. It is determined by ensemble averaging (time averaging).

That is, the response vector of the terminal user 1 is obtained as follows.

[0012]

(Equation 1)

On the other hand, the response vector of the terminal user 2 is obtained as follows.

[0014]

(Equation 2)

In the following, it will be proved that the ensemble average of the product of the received signal X (t) and the complex conjugate S ^* (t) of the modulated signal becomes a response vector, taking the case of the terminal user 1 as an example. .

First, the received signal X ₁ (t) and the terminal user 1
The expansion of E [X ₁ (t) S ₁ ^* (t)], which is the ensemble average of the product of the modulated signal from S and the complex conjugate S ₁ ^* (t), is as follows.

E [X ₁ (t) S ₁ ^* (t)] = E [(h ₁₁ S ₁ (t) + h ₁₂ S ₂ (t) + N ₁ (t)) S ₁ ^* (t)] = E _{[h 11 S 1 (t)} S 1 * (t) + h 12 S 2 (t) S 1 * (t) + N 1 (t) S 1 * (t)] ... (5) where, S ₁ ^* (T) is the complex conjugate of S ₁ (t), and S ₁
^* (T) has no correlation between S ₂ (t) and N ₁ (t), so the following equation is obtained.

E [S ₁ (t) S ₁ ^* (t)] = 1 (6) E [S ₂ (t) S ₁ ^* (t)] = 0 (7) E [N ₁ (t) S ₁ ^* (t)] = 0 (8) When these equations (6) to (8) are substituted into equation (5), E
[X ₁ (t) S ₁ ^* (t)] = h ₁₁ .

Similarly, E [X ₂ (t) S ₁ ^* (t) is an ensemble average of the product of the received signal X ₂ (t) and the complex conjugate S ₁ ^* (t) of the modulated signal from the terminal user 1. )] Is as follows.

E [X ₂ (t) S ₁ ^* (t)] = E [(h ₂₁ S ₁ (t) + h ₂₂ S ₂ (t) + N ₂ (t)) S ₁ ^* (t)] = E [(H ₂₁ S ₁ (t) S ₁ ^* (t) + h ₂₂ S ₂ (t) S ₁ ^* (t) + N ₂ (t) S ₁ ^* (t)] (9) The following equation is obtained in addition to the equations (6) and (7).

E [N ₂ (t) S ₁ ^* (t)] = 0 (10) By substituting these equations (6), (7) and (10) into equation (9), E [X ₂ (t) becomes the ^{_{S 1 * (t)] =}} h 21.

From the above, the received signal X at each antenna element
By ensemble-averaging the product of ₁ (t), X ₂ (t) and the complex conjugate S ₁ ^* (t) of the modulation signal of terminal user 1, coefficients h ₁₁ and h ₂₁ , that is, as shown in equation (3) It is understood that the response vector of the terminal user 1 is calculated.

The method of calculating the response vector of terminal user 2 shown in equation (4) is the same as the method of calculating the response vector of terminal user 1 described above, and a description thereof will be omitted.

Returning to FIG. 13, the circuit configuration shown there is as follows:
This is for calculating a response vector of a signal received from one terminal user among two terminal users.

The signals X ₁ (t) and X ₂ (t) received by the antenna elements 202 and 203 respectively are converted into a signal
After performing well-known signal processing such as diversity processing or adaptive array processing, the signal is supplied to the demodulation processing unit 205. Demodulation processing section 205 demodulates the received signal to generate bit string data of a corresponding terminal user (for example, terminal user 1), outputs the bit string data as demodulated data, and provides the same to remodulation processing section 206.

Remodulation processing section 206 remodulates the given demodulated data to generate a complex conjugate S ₁ ^* (t) of the corresponding modulated signal of terminal user 1. Generated signal S
₁ ^* (t) is given to one input of each of the multipliers 200 and 201. The signals X ₂ (t) and X ₁ (t) received by the antenna elements 203 and 202 are supplied to the other inputs of the multipliers 200 and 201 through delay elements 207 and 208, respectively. The delay elements 207 and 208 function as timing adjustment means for adjusting the timing of the received signals X ₂ (t) and X ₁ (t) to the signal S ₁ ^* (t) remodulated by the remodulation processing unit 206. .

The multiplier 201 has the timing adjusted.
Received signal X₁(T) and the remodulated signal S₁ ^*Multiply with (t)
And the resulting X₁(T) S₁ ^*Average processing of (t)
Unit 209. The multiplier 200
Received signal X_Two(T) and the remodulated signal S₁ ^*(T) and
Multiply and the resulting X_Two(T) S₁ ^*Average (t)
This is given to the processing unit 209. The averaging processing unit 209
Take the ensemble average of the multiplication result of
Thus, the response vector of the terminal user 1 is calculated.

The configuration shown in FIG. 13 is for calculating only the response vector of terminal user 1 among the two terminal users. However, in reality, there are cases where it is necessary to obtain the response vectors of all of the plurality of terminal users.

For example, a well-known PD for transmitting data of a plurality of terminal users by spatially dividing one time slot at the same frequency by adaptive array processing.
In a receiving device of a radio communication system of the MA (Path Division Multiple Access) system, it is necessary to estimate all response vectors of a plurality of terminal users that can be connected to a channel of the same time slot and take a correlation between them. If the correlation values of the two terminal users approach one, it is determined that the directions of arrival of the signal radio waves of the two terminal users are close to each other, and processing such as changing channel assignment is performed. become.

Therefore, in order to accommodate a plurality of terminal users, it is necessary to provide a plurality of circuit configurations for one terminal user shown in FIG. 13 in parallel.

FIG. 14 is a schematic block diagram showing a conventional radio receiving apparatus having a function of estimating response vectors of two terminal users as an example of such a radio receiver corresponding to a plurality of terminals.

The configuration shown in FIG. 14 is obtained by sharing two antenna elements 202 and 203 and arranging two circuit configurations for response vector estimation shown in FIG. 13 in parallel. Averaging section 2 in the circuit configuration in the upper part of FIG.
From 09, the response vector (formula (3)) of the terminal user 1 is output as described above. On the other hand, the averaging unit 217 in the lower circuit configuration (same as the upper circuit) outputs the response vector (Equation (4)) of the terminal user 2. The circuit configuration at the lower stage for calculating the response vector of terminal user 2 and its operation are basically the same as the description of the circuit configuration and the operation for estimating the response vector performed with reference to FIG. 13, and thus will not be repeated here.

[0033]

In the conventional radio receiving apparatus having a response vector estimating function shown in FIG. 13 or FIG. 14, bit stream data obtained by demodulating a received signal once in demodulation processing section 205 (or 213). To the remodulation processing unit 2
A modulated signal of each terminal user is obtained by re-modulating at 06 (or 214) and used for generating a response vector. For this reason, the amount of calculation for estimating the response vector becomes enormous, resulting in an increase in processing time.

If the above-mentioned reception processing is not performed correctly due to the occurrence of interference or the like in the received signal, an error occurs in the estimation of the response vector, and the above-described various characteristics are evaluated.
The calculation of the weight vector, the adaptive array processing, and the like are not performed correctly. Therefore, the accuracy of the wireless receiving apparatus is deteriorated as a whole.

Therefore, an object of the present invention is to provide a radio receiving apparatus and a response vector estimating method capable of estimating a response vector without a large amount of calculation.

Another object of the present invention is to provide a radio receiving apparatus and a response vector estimating method which prevent the accuracy of the radio receiving apparatus from deteriorating when a reception error occurs.

[0037]

According to the first aspect of the present invention, a radio receiving apparatus for receiving a signal from a mobile terminal device using a plurality of antennas comprises a signal extracting means, a forced phase synchronizing means, , Response vector generating means. The signal extracting means performs adaptive array processing on signals received by a plurality of antennas to extract a signal from a desired mobile terminal device. The forced phase synchronization means forcibly synchronizes the phase of each symbol point of the extracted signal with the phase of the closest signal reference point among the predetermined signal reference points. The response vector generation means generates a response vector of a signal from a desired mobile terminal device based on the signals received by the plurality of antennas and the signal phase-synchronized by the forced phase synchronization means.

According to the invention described in claim 2, according to claim 1
Described above detects a phase change between two symbols of the signal phase-synchronized by the forced phase synchronization means, and based on a predetermined correspondence between the phase difference and the data, detects the detected phase change. The apparatus further includes demodulated data output means for outputting corresponding data as demodulated data.

According to the invention described in claim 3, according to claim 1
The wireless receiving device described in (1) detects a phase change between two symbols of the signal extracted by the signal extracting means, and detects a data corresponding to the detected phase change based on a predetermined correspondence between the phase difference and the data. And demodulated data output means for outputting the demodulated data as demodulated data.

According to the invention set forth in claim 4, according to claim 2,
Alternatively, the wireless receiving device described in 3 is an error determination unit that determines whether a reception error has occurred in the demodulated data output by the demodulation data output unit, and that the reception error has occurred by the error determination unit. Once determined,
Means for disabling generation of a response vector by the response vector generation means.

According to the invention set forth in claim 5, according to claim 1,
5. In the wireless reception device according to any one of to 4, the response vector generation unit includes a multiplication unit that multiplies each of the signals received by the plurality of antennas and the phase-synchronized signal, and a multiplication result of each of the multiplication results. Means for taking a time average.

According to the invention of claim 6, according to claim 1,
In the wireless receiving apparatus according to any one of the above, the predetermined signal reference point is composed of two sets of four points, one set and four points alternately alternated for each symbol.
Are the eight reference points.

According to the seventh aspect of the present invention, a radio receiving apparatus for receiving a signal from a mobile terminal device using a plurality of antennas performs parallel processing on signals received by the plurality of antennas to obtain a plurality of mobile terminals. A plurality of response vector estimating means for estimating each response vector of the device are provided. Each of the plurality of response vector estimation units includes a signal extraction unit, a forced phase synchronization unit, and a response vector generation unit. The signal extracting means performs adaptive array processing on signals received by a plurality of antennas to extract a signal from a corresponding mobile terminal device. The forced phase synchronization means forcibly synchronizes the phase of each symbol point of the extracted signal with the phase of the closest signal reference point among the predetermined signal reference points. The response vector generation unit generates a response vector of a signal from the corresponding mobile terminal device based on the signals received by the plurality of antennas and the signal phase-synchronized by the forced phase synchronization unit.

According to the invention of claim 8, according to claim 7,
Wherein each of the plurality of response vector estimating means detects a phase change between two symbols of the signal phase-synchronized by the forced phase synchronizing means, and determines a predetermined correspondence between the phase difference and the data. And demodulated data output means for outputting data corresponding to the detected phase change as demodulated data based on the demodulated data.

According to the invention of claim 9, according to claim 7,
Wherein each of the plurality of response vector estimating means detects a phase change between two symbols of the signal extracted by the signal extracting means, and based on a predetermined correspondence between the phase difference and the data. And demodulated data output means for outputting data corresponding to the detected phase change as demodulated data.

According to the tenth aspect of the present invention, in the wireless receiving apparatus according to the eighth or ninth aspect, each of the plurality of response vector estimating means includes a reception error in the demodulated data output by the demodulated data output means. Error determination means for determining whether or not a response vector has occurred, and means for disabling generation of a response vector by the response vector generation means when the error determination means determines that a reception error has occurred. .

According to the eleventh aspect of the present invention, in the wireless receiving apparatus according to any one of the seventh to tenth aspects,
The response vector generation means includes a multiplication means for multiplying each of the signals received by the plurality of antennas and the phase-synchronized signal, and a means for taking a time average of each of the multiplication results.

According to the twelfth aspect of the present invention, in the wireless receiving apparatus according to any one of the seventh to eleventh aspects,
The predetermined signal reference point is 1 which alternates every symbol.
Π / 4 shift QP composed of 2 sets of 4 points
These are the eight reference points of SK.

According to the thirteenth aspect of the present invention, the response vector estimating method in the radio receiving apparatus for receiving a signal from a mobile terminal apparatus using a plurality of antennas is a method for adaptive array processing of signals received by a plurality of antennas. Extracting a signal from a desired mobile terminal device by performing the following, and forcibly synchronizing the phase of each symbol point of the extracted signal with the phase of the closest signal reference point among predetermined signal reference points. , Signals received on multiple antennas,
Generating a response vector of a signal from a desired mobile terminal device based on the signal whose phase has been synchronized by the step of forcibly synchronizing.

According to a fourteenth aspect of the present invention, in the response vector estimating method according to the thirteenth aspect, a phase change between two symbols of a signal phase-synchronized by the step of forcibly synchronizing is detected, The method further includes a step of outputting data corresponding to the detected phase change as demodulated data based on a predetermined correspondence between the phase difference and the data.

According to a fifteenth aspect of the present invention, in the response vector estimating method according to the thirteenth aspect, a phase change between two symbols of the signal extracted in the signal extracting step is detected, and the phase difference and the phase difference are detected. The method further includes a step of outputting data corresponding to the detected phase change as demodulated data based on a predetermined correspondence relationship with the data.

According to a sixteenth aspect of the present invention, in the response vector estimating method according to the fourteenth or fifteenth aspect, it is determined whether or not a reception error has occurred in the demodulated data output in the step of outputting the demodulated data. And a step of disabling the generation of a response vector by the step of generating a response vector when the determination step determines that a reception error has occurred.

According to a seventeenth aspect of the present invention, in the response vector estimating method according to any one of the thirteenth to sixteenth aspects, the step of generating a response vector includes the steps of: Multiplying the phase-synchronized signal; and taking a time average of each of the results of the multiplication.

According to the eighteenth aspect of the present invention, in the response vector estimating method according to any one of the thirteenth to seventeenth aspects, the predetermined signal reference point is a set of four points that alternate alternately for each symbol. Π / 4 composed of two sets
These are the eight reference points of the shift QPSK.

Therefore, according to the present invention, after the adaptive array processing is performed on the received signal, the extracted signal is forcibly synchronized with the phase of a predetermined signal reference point, so that conventionally demodulated data is The modulated signal of each terminal user, which has been obtained by the re-modulation processing, is directly obtained, and the amount of calculation can be significantly reduced.

Further, according to the present invention, when a reception error is detected in the demodulated data, the estimation of the response vector is stopped, thereby preventing the accuracy of the radio receiving apparatus from being degraded by an erroneous response vector. can do.

[0057]

Embodiments of the present invention will be described below in detail with reference to the drawings. In the drawings, the same or corresponding portions have the same reference characters allotted, and description thereof will not be repeated.

[First Embodiment] FIG. 1 is a functional block diagram of a radio receiving apparatus having a response vector estimating function according to a first embodiment of the present invention.

Referring to FIG. 1, antenna elements 102, 1
03 respectively, the signals X ₁ (t) and X ₂ (t)
Each of them is applied to one input of multipliers 104 and 105, and is also applied to multiplier 1 via delay elements 108 and 109.
01 and 100 are also provided to one input.

To the other inputs of the multipliers 104 and 105, a weight vector described later is input from a weight calculation circuit (not shown). The multiplication results obtained by the multipliers 104 and 105 are added by an adder 106, and the result is provided to a forced phase synchronization unit 107. As will be described in detail later, the output of the adder 106 is a signal having a large signal component (high SINR) of the desired terminal user extracted by the interference cancellation operation by the adaptive array processing. Due to the influence of waves and noise, the signal is slightly offset from the original modulated signal of the desired terminal user.

Therefore, the forced phase synchronization section 107 forcibly synchronizes the signal extracted by the adaptive array processing with a reference signal point on the (I, Q) coordinates described later.
By the forced phase synchronization, the original modulation signal from the terminal user, which was obtained by re-modulating the bit string data obtained by demodulating the received signal once in the conventional example of FIG.
It can be obtained directly.

Briefly speaking, for example, PHS (Pers
On the other hand, signals used for communication in the onal handyphone system, etc. are always π / 4 shifted QPSK (Quadri
It has a true signal point at any of the signal reference points of phasePhase Shift Keying. The signal after the adaptive array processing becomes a signal substantially near the signal point of the modulated signal from the actual terminal user if the interference removal operation is correctly performed, and is distributed near the signal reference point on the (I, Q) coordinate. are doing. Therefore, using the maximum likelihood estimation method, the signal point on the (I, Q) coordinate of the signal subjected to the adaptive array processing is represented by π /
The signal subjected to the adaptive array processing is matched to the signal point of π / 4 shift QPSK at which the Euclidean distance from the signal point that can be taken by 4-shift QPSK becomes the minimum value by forced phase synchronization processing, thereby realizing the actual signal from the terminal user. It is configured to obtain modulated data. Details of the above-described adaptive array processing and forced phase synchronization processing will be described later.

Returning to FIG. 1, modulated signal S ₁ (t) of terminal user 1 is output from forced phase synchronization section 107, and complex conjugate processing is performed by complex conjugate output processing section 110.
S ₁ ^* (t), which is the complex conjugate of S ₁ (t), is output and provided to the other input of each of multipliers 101 and 100. On the other hand, as described above, the received signals X ₁ (t) and X ₂ (t) whose timing has been adjusted by the delay elements 108 and 109 are input to one input of each of the multipliers 101 and 100.

Multiplier 101 multiplies received signal X ₁ (t) by modulated signal S ₁ ^* (t), and the result X
₁ (t) S ₁ ^* (t) is given to the averaging unit 112. Multiplier 100 receives received signal X ₂ (t) and modulated signal S
₁ ^* (t) and the result X ₂ (t) S
₁ ^* (t) is given to the averaging unit 112.

The averaging unit 112 calculates an ensemble average of these multiplication results, and calculates a response vector of the terminal user 1 as shown in equation (3).

On the other hand, the output of forced phase synchronization section 107 is applied to differential decoding processing section 111, demodulated and output as bit string data, and also applied to error check section 114.

In the adaptive array processing, the influence of the direction of arrival of the interference wave on the direction of arrival of the radio wave (desired wave) from the desired terminal user, the difference in the received power between the desired wave and the interference wave,
If the desired wave cannot be extracted due to various factors such as
That is, a reception error may occur. A typical example of such a reception error is CRC (Cyclic Red).
undancy check) error, UW (unique word) error, and the like.

The error check unit 114 determines whether or not such a reception error has occurred in the demodulated data.
If so, the switch 113 is opened to disable the supply of the response vector from the averaging unit 112.

The processing of differential decoding processing section 111 and error check section 114 will be described later.

FIG. 2 is a block diagram showing a hardware configuration for realizing the radio receiving apparatus according to the first embodiment of the present invention shown in the functional block diagram of FIG.

Referring to FIG. 2, a plurality of, for example, four
Antenna ANT₁, ANT_Two, ANT _Three, ANT_FourReceived by
The signal from the selected terminal user is transmitted to the corresponding RF circuit R
F₁, RF_Two, RF_Three, RF_FourAfter amplification in
/ D converter AD₁, AD_Two, AD_Three, AD_FourWith digital signal
Is converted to

A / D converters AD ₁ , AD ₂ , AD ₃ , AD ₄
The output of the digital signal processor (hereinafter, DS
P) 10, the operation of the embodiment of the present invention is:
The DSP 10 implements the software.

In the DSP 10 shown in FIG. 2, the main processing executed by software by the DSP is “adaptive array processing”, “forced phase synchronization processing”, “reception response vector estimation processing”, “differential decoding processing”, And "error check processing" are listed over time. These processes will be described in detail below.

Finally, the data from the desired terminal user is demodulated and output to the outside from the DSP 10 in FIG. 2, and the estimated reception response vector is also output.

FIG. 3 shows a DS according to an embodiment of the present invention.
It is a figure for explaining the flow of the whole processing of P10, and the principle. Note that, of the processing by the DSP 10 shown in FIG. 2, the calculation process itself of the response vector estimation processing has already been described in detail with reference to FIG. 13, and thus will not be repeated here. The error check processing will be described later separately from FIG.

In FIG. 3, four reception signal lines from the four A / D converters in FIG. 2 are indicated by one signal line for convenience of description, and are referred to as "reception signals". .

The received signal is supplied to the DSP via a receiving filter 11 not shown in the hardware configuration diagram of FIG.
10 is input.

As described above, a signal generally used for communication in a PHS or the like always has a true signal point at any one of the signal reference points of π / 4 shift QPSK at each symbol point (see FIG. 1). 8 indicated by a circle at each (I, Q) coordinate of 3
point). However, the I and Q phases of the signal radio wave actually received by the base station are based on the π / 4 shift QPSK signal reference as depicted by the (I, Q) coordinate constellation shown in FIG. The point has not converged.

For the received signal in such a state, the DSP
10, an adaptive array process is performed first.

In the adaptive array processing, a weight vector composed of a reception coefficient (weight) for each antenna is calculated based on a received signal and adaptively controlled.
This is a process for accurately extracting a signal from a desired terminal user.

FIG. 4 is a functional block diagram for functionally explaining the adaptive array processing by the DSP 10. As shown in FIG.

Referring to FIG. 4, weight calculation circuit 20
Calculates a weight vector W (t) composed of weights for each antenna by an algorithm described later, and receives a complex signal with a received signal X (t) from the corresponding antenna by multipliers MP ₁ , MP ₂ , MP ₃ , and MP ₄ . Multiply. The sum Y (t) of the multiplication results is obtained by the adder 21, and this Y (t) is expressed as a complex multiplication sum as follows: Y (t) = W (t) ^H X (t) where , W (t) ^H represent the transpose of the complex conjugate of the weight vector W (t).

The result of the complex multiplication and sum Y (t) described above
Is supplied to one input of a subtractor 22, and an error from a known reference signal d (t) previously stored in a memory of the base station is obtained. The reference signal d (t) is a known signal common to all users included in the received signal from the terminal user. For example, in the PHS, a preamble section composed of a known bit string in the received signal is used. .

The weight calculation circuit 20 executes processing for updating the weight coefficient so as to reduce the square of the error calculated by the subtractor 22. In the adaptive array processing, such updating of the weight vector (weight learning) is adaptively performed according to a change in time or a propagation path characteristic of a signal radio wave, and an interference wave component or noise is extracted from the received signal X (t). The signal Y (t) from the desired terminal user is extracted.

In the weight calculation circuit 20 according to the embodiment of the present invention, as described above, the steepest descent method based on the square of the error (Minimum Mean Square Error: MMS)
The weight vector is updated, that is, weight learning is performed by E). More specifically, the weight calculation circuit 20 uses the MMSE RLS (Recurs
ive Least Squares) algorithm and LMS (Least Mea
n Squares) algorithm.

The adaptive array processing technology based on the MMSE and the RLS algorithm and the LMS algorithm based on the MMSE are known technologies. For example, “Adaptive signal processing using an array antenna” by Nobuyoshi Kikuma
(Science & Technology Publishing), pages 35 to 49, “Chapter 3 M
MSE Adaptive Array ".

FIG. 5 is a flowchart showing processing when the DSP 10 executes the operation of the functional block diagram of the adaptive array shown in FIG. 4 by software.

As described above, in the adaptive array processing, the complex multiplication sum Y (t) and the predetermined reference signal d
(T) An error from (t) (a known signal value such as a preamble unique word) is obtained. However, since the reference signal value does not exist in all the sections of the received signal, the received signal is set in the section where the reference signal is known. Different processing is performed depending on whether or not there is.

Referring to FIG. 5, when the adaptive array processing is started, time t is set to the first symbol in step S1. For example, one frame of the received signal of the PHS is composed of 1 to 120 symbols, of which a signal known section exists in the first half.

Next, in step S2, the initialization of the correlation matrix P, the forgetting factor λ, the weight vector W, and the step size μ is performed.

Next, in step S3, the symbol t
It is determined whether or not = 1 is within the section where the reference signal is known, and since it is within the section where the reference signal is known, the RLS algorithm is executed in steps S4 to S8 (for details of the RLS algorithm, refer to the above document).

First, in step S4, a Kalman gain vector K (t) at time t is calculated. The Kalman gain vector is K (t) = T (t) / (1 + X
^H (t) T (t)), where T (t) = λP
(T-1) X (t).

Next, in step S5, a known reference signal d (t) is read from a memory in the base station.

Next, in step S6, the error e (t) between the reference signal and the complex multiplication sum at time t is calculated as follows: e (t) = d (t) -W ^H (t -1) X (t) In step S7, the weight vector W (t) at time t is calculated using the Kalman gain vector K (t) as follows: W (t) = W ( t-1) + e ^* (t) K (t) In step S8, the correlation matrix P (t) at time t is updated as follows: P (t) = λP (t) − Above K (t) ^H T (t), the RLS algorithm ends. If the symbol t has not reached the last symbol of the frame in step S9, the symbol t is incremented and the process returns to step S3. As long as it is determined in step S3 that the symbol t is within the section where the reference signal is known, the RLS algorithm of steps S4 to S8 is repeatedly executed, and in step S7, the weight vector W (t ) Is calculated.

On the other hand, in step S3, the symbol t
Is determined to be a section in which the reference signal is unknown, the LMS algorithm is executed in steps S10 to S12 (for details of the LMS algorithm, refer to the above document).

In the above-described steps S4 to S8, the weight learning is performed using the received signal X (t) and the reference signal d (t) because the received signal is in the section where the reference signal exists. Steps S10 to be described below
In the processing of S12, since the reference signal does not exist in the received signal, the complex multiplication sum of the weight vector calculated one symbol before and the received signal, and the π / 4 shift QP
Weight learning is performed using the phase difference between the SK signal reference point and the SK signal reference point as an error.

First, in step S10, the reference signal d is calculated from the weight vector W (t-1) one symbol before.
Inversely calculate (t). That is, d (t) = Det [W
(T-1) ^H X (t)], and the 4 / π shift QPSK with the shortest Euclidean distance from the I and Q signals at the signal point.
Is selected, and the signal d (t) is added to the signal reference point.
Take.

Next, in step S11, the error e (t) between the reference signal and the complex multiplication sum at time t is calculated as in step S6 described above: e (t) = d (t)- W ^H (t−1) X (t) Then, in step S12, the time t
Is calculated as follows: W (t) = W (t−1) + μe ^* (t) X (t) With the above, the LMS algorithm ends, and in step S9, the symbol t If the last symbol has not been reached, the symbol t is incremented and the process returns to step S3. Then, as long as it is determined in step S3 that the symbol t is outside the section where the reference signal is known,
The LMS algorithm in steps S10 to S12 is repeatedly executed, and the weight vector W (t) at that time is calculated in step S12 for each symbol t.

If it is determined in step S9 that the symbol t has reached t = 120, which is the last symbol of the frame, the adaptive array processing ends.

If the received signal before the adaptive array processing is X (t), the processed received signal X '(t)
Is expressed as X ′ (t) = W (t) ^H X (t).

As can be understood from the flow chart of FIG. 5, the RLS algorithm of steps S4 to S8 requires a long time for weight learning due to its complicated processing, but has the advantage of fast convergence (for example, about 10 symbols). At which the weights converge). In contrast, steps S10 to S1
The LMS algorithm 2 does not require much time for weight learning because the processing is simplified, but has a disadvantage that convergence is slow (a large number of symbols are required for weight learning).

Thus, the RLS algorithm and the LMS
Algorithms have advantages and disadvantages, and adaptive array processing may be realized by appropriately combining the two in accordance with the performance of a receiver to be realized. That is, FIG.
Is a mere example, and when there is a reference signal, R
The LMS algorithm may be used instead of the LS algorithm, and the RLS algorithm may be used instead of the LMS algorithm when the reference signal is unknown.

As described above, in the signal generated by the adaptive array processing for performing the weight learning based on the known reference signal, the influence of the frequency offset and the like is considerably eliminated. This is because there is no such offset or noise in the reference signal stored in the memory in advance, and the accuracy of the signal itself generated by weight learning based on this reference signal is also improved.

Returning to FIG. 3, the (I, Q) coordinates shown in (ii) are such that the signal point (●) of the extracted desired signal after the adaptive array processing is the true signal reference point (○). Concentrate around.

As described above, the true signal point of the PHS is always at one of the eight signal reference points (）) of the 4 / π-shifted QPSK, but the residual interference that could not be suppressed by the adaptive array processing. Due to factors such as wave components, noise, and problems in the accuracy of weight learning, there are some data in which the signal points (●) of the extracted symbols do not completely match the eight signal reference points (○).

For this reason, the DSP 10 executes the forced phase synchronization processing after the adaptive array processing.
This process forcibly synchronizes the I and Q phases (●) of the signal points extracted by the adaptive array with the I and Q phases of the closest reference point among the signal reference points (○) of π / 4 shift QPSK. It is to let. That is, the I / Q phase of the extracted signal point is 4 / π-shifted QPSK so that the (I, Q) coordinate shown in (ii) of FIG. 3 becomes the (I, Q) coordinate shown in (iii). A process is performed to make the phase coincide with the phase of the signal reference point.

FIG. 6 shows such forced phase synchronization processing as D
FIG. 7 is a flowchart showing a process when the SP 10 executes by software.

Referring to FIG. 6, when the forced phase synchronization processing is started, time t is set to the first symbol in step S21.

Then, in step S22, the I and Q signals of the signal after the adaptive array processing are respectively (X
(T), Y (t)).

Next, in step S23, it is determined whether the symbol t is even or odd. Although it has been mentioned earlier that the true signal point of the PHS is located at any of the eight signal reference points of the 4 / π shift QPSK, more precisely, these eight signal reference points are: One set that alternates for each symbol is composed of two sets of four reference points.

More specifically, when the symbol t is an even number, as shown in step S24, the π / 4 shift QPS
The signal points of K are (1, 0), (0, 1), (-1,
0) and (0, -1).

On the other hand, when the symbol t is an odd number, as shown in step S25, the signal points of the π / 4 shift QPSK are (1, 1) / 2 ^1/2 , (-1, 1) / 2 ^{1 / 2} , (-
Four points of (1, -1) / 2 ^1/2 and (1, -1) / 2 ^1/2 are set.

In step S26, when the symbol t is even or odd, the I and Q signal coordinates (X (t), Y (t)) of the signal after the adaptive array processing are performed.
The signal reference point having the shortest Euclidean distance with respect to is selected from among the four signal reference points in any set corresponding to the time t, and (X (t), Y (t)) is set to the signal reference point. Are forcibly synchronized with the I and Q signals.

If it is determined in step S27 that the symbol t has not reached the last symbol of the frame, the symbol t is incremented in step S28, and the flow returns to step S23. Then, the forced phase synchronization processing for each symbol of the signal subjected to the adaptive array processing is performed until the symbol of the frame ends (t = 1).
(Until it reaches 20).

With the above-described adaptive array processing and forced phase synchronization processing, it is possible to reproduce an actual modulated signal S (t) from a desired terminal user and to use the reproduced signal S (t) for response vector estimation processing. The description of the response vector estimation process itself will not be repeated.

Returning to FIG. 3, the DSP 10 executes differential decoding processing after forced phase synchronization processing.

This operation signal processing detects a phase change between two consecutive symbols in a time series of a signal whose phase has been forcibly synchronized, and based on a predetermined relationship between a phase difference and demodulated data. , 2 corresponding to the detected phase change
It outputs bit data as demodulated data.
That is, if there are four patterns of phase differences, 00, 01, 1
It is possible to output four 2-bit data of 0 and 11.

In the example shown in FIG. 3, when the phase difference Δθ between two symbols is 3π / 4, 01 demodulated data is output.

FIG. 7 shows such a differential decoding process performed by a DSP.
FIG. 10 is a flowchart showing a process when software 10 executes by software.

Referring to FIG. 7, after the completion of the forced phase synchronization processing of FIG. 6, differential decoding processing is started.
At 31, the time t is set to the first symbol.

Next, in step S32, the phase difference Δθ between the signal of the symbol at t = 1 and the signal after one symbol is calculated by the following equation: Δθ = atan (Y (t + 1) / X (t + 1) ) -At
an (Y (t) / X (t)) (atan means arc tangent) Next, in step S33, a conversion table between phase difference and data is (-3π / 4, 11), ( 3π / 4,01),
Based on (π / 4,00) and (−π / 4,10), demodulated data is generated from the phase difference detected in step S32.

In step S34, if the symbol t has not reached the last symbol of the frame, the symbol t is incremented in step S35 and the process returns to step S32. Then, the differential decoding process for each symbol of the signal is repeatedly executed until the symbol of the frame ends (until t = 120).

Next, FIG. 8 is a flowchart showing an error check process by the DSP 10 shown in FIG.

First, in step S41, it is determined whether or not a CRC error or a UW error, which is a typical reception error, has occurred in the demodulated data obtained by the above-described differential decoding processing (FIG. 7).

If such a reception error has not occurred, in step S41, the modulated signal S (t) of the terminal user obtained by the forced phase synchronization processing (FIG. 6) is received by the antenna element. Multiplication with the obtained signal X (t) and ensemble averaging of the result,
The response vector of the terminal user is estimated.

On the other hand, if it is determined in step S41 that a reception error has occurred, the process proceeds to step S4.
The process is terminated without estimating the response vector of No. 2.

As a result, when a reception error occurs in the demodulated data, it is possible to prevent the accuracy of the radio receiving apparatus from deteriorating due to an incorrect response vector.

[Second Embodiment] FIG. 9 is a functional block diagram of a radio receiving apparatus having a response vector estimating function according to a second embodiment of the present invention.

The radio receiving apparatus according to the first embodiment shown in the functional block diagram of FIG. 1 is for calculating only the response vector of terminal user 1 out of two terminal users. However, as described in connection with the conventional example of FIGS. 13 and 14, there are cases where it is necessary to obtain the response vectors of all the plurality of terminal users.

FIG. 9 is a functional block diagram showing a radio receiver according to a second embodiment of the present invention having a function of estimating response vectors of two terminal users as an example of such a radio receiver corresponding to a plurality of terminals. It is.

The configuration shown in FIG. 9 uses the two antenna elements 102 and 103 in common and employs the first embodiment shown in FIG.
Are arranged in parallel (at the upper stage and at the lower stage). The averaging unit 112 in the circuit configuration in the upper part of FIG. 9 outputs the response vector (formula (3)) of the terminal user 1, as described in detail with reference to FIGS. On the other hand, the averaging unit 124 in the same circuit configuration in the lower part of FIG.
Expression) is output. The circuit configuration at the lower stage for estimating the response vector of terminal user 2 and its operation are the same as those of the circuit configuration for estimating the response vector performed with reference to FIG. 1 and the description thereof, and thus will not be repeated here.

[Third Embodiment] FIG. 10 is a functional block diagram of a radio receiving apparatus having a response vector estimating function according to a third embodiment of the present invention. The radio receiving apparatus according to the third embodiment shown in FIG. 10 is the same as the radio receiving apparatus according to the first embodiment shown in FIG. 1 except for the following points.

That is, in the first embodiment shown in FIG. 1, differential decoding processing is performed by differential decoding processing section 111 on a signal whose phase has been forcibly synchronized by forced phase synchronization section 107. On the other hand, in the third embodiment shown in FIG. 10, the differential decoding processing unit 111 performs differential decoding on the signal output from the adder 106 and subjected to the adaptive array processing.

In the third embodiment shown in FIG. 10, differential decoding processing is performed on a signal that is not forcibly phase-synchronized with a reference signal point. Therefore, the third embodiment shown in FIG. It is considered that the wireless receiving device according to mode 1 is more preferable.

Regarding the estimation of the response vector, in both Embodiments 1 and 3, the estimation processing is performed using the modulation signal of the terminal user obtained by the forced phase synchronization, and the difference between the two embodiments is different. There is no.

FIG. 11 is a block diagram showing a hardware configuration for realizing the radio receiving apparatus according to the third embodiment of the present invention shown in FIG.

The respective processes listed over time in the DSP 10 of FIG. 11 have already been described in detail with reference to FIGS. 3 to 8 in relation to the first embodiment. The description of the processing is not repeated.

[Fourth Embodiment] FIG. 12 is a functional block diagram of a radio receiving apparatus having a response vector estimating function according to a fourth embodiment of the present invention.

The radio receiving apparatus according to the third embodiment shown in the functional block diagram of FIG. 10 is for calculating only the response vector of terminal user 1 out of two terminal users. However, as described above, there are cases where it is necessary to obtain the response vectors of all of the plurality of terminal users.

FIG. 12 is a functional block diagram showing a radio receiving apparatus according to a fourth embodiment of the present invention having a function of estimating response vectors of two terminal users as an example of such a radio receiver supporting a plurality of terminals. It is.

In the configuration shown in FIG. 12, two antenna elements 102 and 103 are shared, and two circuit configurations for estimating a response vector according to the third embodiment shown in FIG. )). FIG.
From the averaging processing unit 112 in the circuit configuration in the upper stage,
As already described in detail in connection with FIGS. 1 to 8,
The response vector (Equation (3)) of the terminal user 1 is output. On the other hand, the averaging processing unit 124 having the same circuit configuration in the lower part of FIG. 12 outputs the response vector (Equation (4)) of the terminal user 2. The lower circuit configuration for estimating the response vector of the terminal user 2 and its operation are as follows:
The description of the circuit configuration and operation for estimating the response vector performed in FIG. 10 is the same as that of FIG.

In each of the above embodiments, the case where π / 4 shift QPSK is used as the modulation method has been described, but the modulation method is not limited to this.

As described above, according to the embodiment of the present invention, a signal received by an antenna element is subjected to adaptive array processing and then forcedly phase-synchronized with a reference signal point. The original modulated signal can be accurately reproduced and used for the response vector estimation processing. Therefore, unlike the related art, it is not necessary to demodulate the received signal once into bit string data and then re-modulate the signal to obtain a modulated signal, and it is possible to significantly reduce the amount of calculation.

When a reception error has occurred in the demodulated data, the estimation of the response vector is stopped to prevent a situation in which the accuracy of the radio receiving apparatus is degraded by an incorrect response vector.

The embodiments disclosed this time are to be considered in all respects as illustrative and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

[0146]

As described above, according to the present invention, the amount of calculation required for estimating a response vector can be significantly reduced, and the processing speed can be increased.

Further, even when a reception error occurs, it is possible to prevent the accuracy of the radio receiving apparatus from being deteriorated by an erroneous response vector.

[Brief description of the drawings]

FIG. 1 is a functional block diagram of a wireless receiving device according to a first embodiment of the present invention.

FIG. 2 is a block diagram schematically showing a hardware configuration of the wireless reception device according to the first embodiment of the present invention.

FIG. 3 is a diagram for explaining overall processing of the DSP according to the first embodiment of the present invention;

FIG. 4 is a functional block diagram for functionally explaining adaptive array processing by the DSP according to the first embodiment of the present invention;

5 is a flowchart showing a process when the DSP executes the operation of the functional block diagram of the adaptive array shown in FIG. 4 by software.

FIG. 6 is a flowchart showing processing when the DSP executes the forced phase synchronization processing according to the first embodiment of the present invention with software.

FIG. 7 is a flowchart showing a process when the DSP executes the differential decoding process according to the first embodiment of the present invention by software.

FIG. 8 is a flowchart showing a process when the DSP executes the error check process according to the first embodiment of the present invention by software.

FIG. 9 is a functional block diagram of a wireless reception device according to a second embodiment of the present invention.

FIG. 10 is a functional block diagram of a wireless reception device according to a third embodiment of the present invention.

FIG. 11 is a block diagram schematically showing a hardware configuration of a wireless reception device according to a third embodiment of the present invention.

FIG. 12 is a functional block diagram of a wireless reception device according to a fourth embodiment of the present invention.

FIG. 13 is a functional block diagram of a conventional wireless receiving device.

FIG. 14 is a functional block diagram of another example of the conventional wireless receiving device.

[Explanation of symbols]

Reference Signs List 10 DSP, 11 reception filter, 20 weight calculation circuit, 21 adder, 22 subtractor, 107, 119
Forced phase synchronization section, 108, 109, 120, 121
Delay element, 110, 122 Demodulation processing unit, 111, 12
3 differential decoding processing unit, 114, 126 error checking unit, 112, 124 averaging processing unit, 113, 125
Switch element.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5J021 AA05 AA06 CA06 DB02 DB03 EA04 FA05 FA14 FA15 FA16 FA17 FA20 FA21 FA26 FA32 GA02 GA08 HA05 HA10 5K004 AA05 FA05 FG00 FH03 FH08 5K059 AA08 BB08 CC03 CC04 DD31 EE02

Claims (18)

[Claims] 1. A radio receiving apparatus for receiving a signal from a mobile terminal device using a plurality of antennas, wherein the signal received from the plurality of antennas is subjected to an adaptive array process to obtain a signal from a desired mobile terminal device. Signal extraction means for extracting a plurality of antennas, forcibly synchronizing the phase of each symbol point of the extracted signal with the phase of the closest signal reference point among predetermined signal reference points, Based on the signal received at and the signal phase-synchronized by the forced phase synchronization means,
A response vector generating unit configured to generate a response vector of a signal from the desired mobile terminal device. 2. A phase change between two symbols of a signal phase-synchronized by the forced phase synchronization means is detected, and a phase change corresponding to the detected phase change is performed based on a predetermined correspondence relationship between a phase difference and data. 2. The radio receiving apparatus according to claim 1, further comprising demodulated data output means for outputting data to be demodulated as demodulated data. 3. A phase change between two symbols of a signal extracted by the signal extracting means is detected, and data corresponding to the detected phase change is determined based on a predetermined correspondence between the phase difference and the data. The radio receiving apparatus according to claim 1, further comprising a demodulated data output unit that outputs the demodulated data. 4. An error determining means for determining whether or not a reception error has occurred in demodulated data output by said demodulated data output means, and it is determined by said error determining means that a reception error has occurred. The radio receiving apparatus according to claim 2, further comprising: a unit that disables generation of a response vector by the response vector generation unit. 5. The response vector generation means, a multiplication means for multiplying each of the signals received by the plurality of antennas and the phase-synchronized signal, and taking a time average of each of the multiplication results. The wireless receiver according to claim 1, further comprising: 6. The method according to claim 1, wherein the predetermined signal reference points are eight reference points of π / 4 shift QPSK, which are composed of two sets, one set and four points, which alternate alternately for each symbol. 5. The wireless receiving device according to any one of 5. 7. A radio receiving apparatus for receiving a signal from a mobile terminal device using a plurality of antennas, wherein the signal received by the plurality of antennas is processed in parallel to each of the response vectors of the plurality of mobile terminal devices. A plurality of response vector estimating means for estimating the signal, and each of the plurality of response vector estimating means performs adaptive array processing on a signal received by the plurality of antennas to extract a signal from a corresponding mobile terminal apparatus. Extraction means, forced phase synchronization means for forcibly synchronizing the phase of each symbol point of the extracted signal with the phase of the closest signal reference point among predetermined signal reference points, and signals received by the plurality of antennas And the signal phase-synchronized by the forced phase synchronization means,
Response vector generating means for generating a response vector of a signal from the corresponding mobile terminal device. 8. Each of the plurality of response vector estimating means detects a phase change between two symbols of the signal phase-synchronized by the forced phase synchronizing means, and sets a predetermined correspondence between a phase difference and data. 8. The radio receiving apparatus according to claim 7, further comprising a demodulated data output unit that outputs data corresponding to the detected phase change as demodulated data based on the demodulated data. 9. Each of the plurality of response vector estimating means detects a phase change between two symbols of the signal extracted by the signal extracting means, and based on a predetermined correspondence between the phase difference and the data, The radio receiving apparatus according to claim 7, further comprising a demodulated data output unit that outputs data corresponding to the detected phase change as demodulated data. 10. An error determining unit for determining whether a reception error has occurred in demodulated data output by the demodulated data output unit, wherein each of the plurality of response vector estimating units includes: 10. The radio receiving apparatus according to claim 8, further comprising: means for disabling generation of a response vector by said response vector generation means when it is determined that a reception error has occurred. 11. The response vector generation means, a multiplication means for multiplying each of the signals received by the plurality of antennas and the phase-synchronized signal, and taking a time average of each of the multiplication results The wireless receiving device according to claim 7, further comprising: 12. The method according to claim 7, wherein the predetermined signal reference points are eight reference points of π / 4 shift QPSK, each of which is composed of two sets of four points which alternate alternately for each symbol. The wireless receiving device according to any one of claims 11 to 11. 13. A method for estimating a response vector in a radio receiving apparatus for receiving a signal from a mobile terminal apparatus using a plurality of antennas, the method comprising: performing adaptive array processing on signals received by the plurality of antennas to perform a desired movement. Extracting a signal from a terminal device; forcibly synchronizing the phase of each symbol point of the extracted signal with the phase of the closest signal reference point among predetermined signal reference points; Generating a response vector of a signal from the desired mobile terminal device based on the signal received in step (a) and the signal phase-synchronized by the forcibly synchronizing step. 14. A phase change between two symbols of a signal phase-synchronized by the forcibly synchronizing step, and the detected phase change is determined based on a predetermined correspondence between a phase difference and data. 2. The method according to claim 1, further comprising the step of outputting data corresponding to.
3. The response vector estimation method according to 3. 15. A phase change between two symbols of the signal extracted in the step of extracting the signal, the phase change corresponding to the detected phase change based on a predetermined correspondence relationship between a phase difference and data. 14. The response vector specifying method according to claim 13, further comprising a step of outputting data as demodulated data. 16. A step of determining whether a reception error has occurred in the demodulated data output in the step of outputting the demodulated data, and it is determined that a reception error has occurred in the determining step. The response vector estimation method according to claim 14, further comprising: disabling generation of a response vector by generating the response vector. 17. The method of claim 17, wherein generating the response vector comprises: multiplying each of the signals received by the plurality of antennas with the phase-synchronized signal; A response vector estimating method according to any one of claims 13 to 16, comprising: 18. The method according to claim 13, wherein the predetermined signal reference points are eight reference points of π / 4 shift QPSK, which are constituted by two sets of one set and four points alternately alternated for each symbol. 18. The response vector estimation method according to any one of items 17.