WO2004032440A1

WO2004032440A1 - Reception device and blind reception method

Info

Publication number: WO2004032440A1
Application number: PCT/JP2003/010284
Authority: WO
Inventors: Mitsuru Uesugi
Original assignee: Matsushita Electric Industrial Co., Ltd.
Priority date: 2002-09-30
Filing date: 2003-08-13
Publication date: 2004-04-15
Also published as: JP2004128697A; JP3588092B2; AU2003255020A1

Abstract

A line estimation candidate generator (152) generates a candidate signal whose phase is varied by the phase difference between the symbol patterns. Phase/amplitude compensators (153-1 to 153-4) compensate the phase and amplitude of the candidate signal to a symbol pattern in which the phase and amplitude have nearest values. Error correction decoders (154-1 to 154-4) perform error correction decoding of the candidate signal whose phase and amplitude are compensated. Error detectors (155-1 to 155-4) judge whether the candidate signal has an error. A selector (156) selects a candidate signal from which no error has been detected, as a correctly demodulated signal.

Description

Specification

Receiving device and blind receiving method

Technical field

The present invention relates to a receiving device and a blind receiving method.

Background art

Generally, there are synchronous detection and delay detection as data transmission methods. Synchronous detection provides better performance than differential detection by using a pilot to notify the signal phase and amplitude standards.

In addition, the pilot is indispensable for the maximum ratio combining of the diversity and the reception of the combined hybrid ARQ and the rake of the CDMA. Therefore, in synchronous detection, an overhead called a pilot is always required.

Also, in the case of differential detection, the first symbol is used as a reference for reception, and thus becomes an overhead. Furthermore, if pilots are inserted in a time-division manner, depending on the speed of line fluctuations, the frequency of insertion will increase considerably, further increasing overhead.

Here, as a method of blind reception, there is a method described in Japanese Patent Laid-Open Publication No. Hei 11-135 188. However, this method can blindly compensate for the phase shift of the carrier signal, but cannot determine which of the symbol patterns the modulated signal corresponds to.

As described above, in the conventional device, a pilot signal is needed to detect a received signal, and the transmission capacity is reduced by the amount of transmission of the pilot signal, thereby lowering the throughput. There is. Disclosure of the invention

An object of the present invention is to provide a receiving apparatus and a blind receiving method that can detect a received signal without requiring a pilot signal.

The purpose of this is to create a plurality of candidate signals whose phase is changed by the phase difference between symbol patterns from the received signal, and correctly receive a signal without error in the result of demodulating this candidate signal. This is achieved by selecting the signal and detecting the received signal without the need for a pilot signal. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a block diagram showing a configuration of a transmitting apparatus and a receiving apparatus according to Embodiment 1 of the present invention,

FIG. 2 is a diagram showing a symbol pattern of the QPSK modulation scheme,

FIG. 3 is a diagram showing an example of a symbol pattern of a received QPSK modulation signal.

FIG. 4 is a diagram showing an example of a symbol pattern of a received QPSK modulation signal.

FIG. 5 is a diagram showing an example of a symbolic pattern of a received QPSK modulation signal.

FIG. 6 is a diagram showing an example of a symbol pattern of a received QPSK modulation signal.

'' Figure 7 shows an example of a histogram, and

FIG. 8 is a block diagram showing a configuration of a receiving apparatus according to Embodiment 4 of the present invention. BEST MODE FOR CARRYING OUT THE INVENTION The gist of the present invention is to generate a plurality of candidate signals whose phase is changed by a phase difference between symbol patterns from a received signal, and to correctly receive a signal in which no error has occurred in a result of demodulating the candidate signal. This is to detect the received signal without selecting a pilot signal.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(Embodiment 1)

FIG. 1 is a block diagram showing a configuration of a transmitting apparatus and a receiving apparatus according to Embodiment 1 of the present invention. The transmitting apparatus 100 in FIG. 1 mainly includes an error correcting bit adding section 101, an error correcting encoder 102, a modulator 103, and a radio transmitting section 104. You.

Error correction bit adding section 101 adds an error correction bit to the transmission data and outputs the result to error correction encoder 102. Error correction encoder 102 applies error correction coding to the transmission data and outputs the result to modulator 103. Modulator 103 modulates transmission data and outputs the result to radio transmission section 104. In the present embodiment, an example in which QPSK modulation is performed will be described.

Radio transmitting section 104 converts the frequency of the transmission data from the baseband frequency to the radio frequency, and transmits the converted signal to the communication partner. The transmission data transmitted here does not include a pilot signal as a reference for compensating the phase and amplitude.

The transmission data to which the pilot signal is not added is blindly received on the receiving side. The receiving apparatus 150 in FIG. 1 includes a radio receiving section 151, a channel estimation candidate generator 152, a phase 振幅 amplitude compensator 153-1-3 to 153-4, and an error correction decoding circuit. 1 5 4—1 to: L 5 4—4, error detectors 1 5 5—1 to 1 5 5—4, and a selector 156.

Radio receiving section 151 receives a signal to which a pilot signal transmitted from transmitting apparatus 100 is not added, and outputs the received signal to channel estimation candidate generator 152. You.

The channel estimation candidate generator 15 2 creates a candidate signal in which the phase of the signal is changed by the phase difference between the symbol patterns, and outputs the candidate signal to the phase 器 amplitude compensator 1 5 3-1 to 1 5 3-4 .

The phase / amplitude compensator 153-1 outputs the candidate signal to the error correction decoder 154-1 after compensating the phase and the amplitude of the candidate signal to a symbol pattern having the closest phase and amplitude. Similarly, the phase / amplitude compensator 1 5 3—2 to 1 5 3—4 compensates for the phase and amplitude of the target signal in the same manner as the phase / amplitude compensator 1 5 3—1, and performs error correction decoding. Output to the unit 1 5 4—2 to 1 5 4—4.

The error correction decoder 154-1 performs error correction decoding on the candidate signal whose phase and amplitude have been compensated, and outputs the result to the error detector 155-1. Similarly, the error-correcting decoder 15 4 4-2 to 15 4-4 performs error correction decoding on the phase-amplitude-compensated signal to obtain an error detector 15 5-2 to 15. Output to 5—4.

The error detector 155-1 determines whether or not the candidate signal is erroneous, and outputs the candidate signal and the determination result to the selector 1556. Similarly, error detectors 155-2 to 15.5-4 determine whether or not the candidate signal is incorrect, and output the candidate signal and the determination result to selector 1556.

The selector 156 selects a candidate signal in which no error is detected as a correctly demodulated signal.

Next, the operation of blind reception of the receiving apparatus according to the present embodiment will be described. In QPSK modulation, data is distinguished by four phases. FIG. 2 is a diagram showing a symbol pattern of the QPSK modulation scheme. In Fig. 2, the horizontal axis shows the I axis and the vertical axis shows the Q axis. On the transmitting side, the four types of data are mapped to one of the symbols 201, 202, 203, or 204 and transmitted.

However, due to the effects of propagation paths such as fading, the receiving side receives the symbol with its phase and amplitude changed. Figure 3 shows the received QPSK modulation format. FIG. 3 is a diagram illustrating an example of a signal symbol pattern. The horizontal axis shows the I axis and the vertical axis shows the Q axis. As shown in FIG. 3, the phase of the symbol 301 changes.

For example, the symbol 301 has the phase of the symbol 201 in FIG. 2 advanced by 20 degrees, the symbol 204 has the phase advanced by 110 degrees, and the symbol 210 has the phase of 210 degrees. Either the phase advanced by 0 degrees or the phase of the symbol 202 advanced by 290 degrees. However, when the phase of the pilot signal is not used as a reference, it is indistinguishable which of the four phase shifts is correct.

Therefore, the channel estimation candidate generator 152 changes the phase of the received signal by 0 degree, 90 degrees, 180 degrees, and 270 degrees. The phase / amplitude compensator 153-1 compensates for the phase and amplitude of the signal whose phase has been changed by 0 degrees. In the symbol 310 of FIG. 3, the phase / amplitude compensator 153-1 returns the phase by 20 degrees.

Similarly, the phase / amplitude compensator 153-2-2 compensates for the phase and amplitude of the signal whose phase has been changed by 90 degrees. The phase 'amplitude compensator 15 3-3 compensates for the phase and amplitude of the signal whose phase has been changed by 180 degrees. Then, the phase ′ amplitude compensator 15 3-4 compensates for the phase and amplitude of the signal whose phase has been changed by 270 degrees.

The signal whose phase has been changed by 0 degree is subjected to error correction decoding in an error correction decoder 154-1 and an error detector 155-1 determines whether or not there is an error. Is done.

Similarly, the signals whose phases are changed by 90 degrees, 180 degrees, and 270 degrees are subjected to error correction decoding in the error correction decoders 154-2-4 to 154-2-4. The error detectors 15 5-2 to 15 5-4 determine whether there is an error. Then, demodulation and decoding are performed on the assumption that the received signal is located at any of the four types of symbols of the QPSK modulation, and a signal on which no error is detected as a result of decoding is selected as a correct signal.

Thus, if there is no noise, as can be seen from the above figure, if it is QPSK, even one point is observed and its phase and its phases 0, 90, 180, and 270 It is sufficient to select the four ways that each of the degrees is added.

When there is noise, the observation results shown in Fig. 4 or Fig. 5 can be obtained. FIGS. 4 and 5 are diagrams illustrating an example of a symbol pattern of a received QPSK modulation scheme signal. In the examples in Figs. 4 and 5, the symbols are scattered by noise, and correct channel estimation cannot be performed with only one point. Therefore, it is necessary to observe several points (the line estimation can be made with fairly good accuracy by looking at all the symbols in one bucket).

In the case of 8PSK, 16QAM, 64QAM, etc., similarly, a unique number of uncertainties are allowed, and candidate signals are generated assuming that the phase and amplitude have changed by the number of symbol types. If the decoding result for which no error is detected is selected, demodulation is possible even without a pilot.

As described above, according to the receiving apparatus of the present embodiment, a candidate signal is generated in which the phase is changed from the received signal to the phase difference between symbol patterns, and an error occurs in the result of demodulating the candidate signal. By selecting a signal that has not been received as a correctly received signal, the received signal can be detected without the need for a pilot signal.

(Embodiment 2)

Embodiment 2 describes an example in which receiving apparatus 150 of the embodiment performs channel estimation by observing a plurality of symbols. FIG. 6 is a diagram illustrating an example of a symbol pattern of a received QPSK modulation signal. In FIG. 6, the horizontal axis represents the axis X (I axis), and the vertical axis represents the axis Y (Q axis).

First, if the received signal of QPSK is not tilted due to the effect of the line, the distribution of points above and below axis X should be symmetric in the region to the right of axis Y. However, in FIG. 6, it can be seen that the distribution above the axis X is more distant from the axis X because of the inclination due to the effects of fading and the like.

The phase-amplitude compensators 153-1 to 153-4 in Fig. 1 are the coordinates of multiple symbols. Observe For example, observe all symbols in one packet.

Then, the phase / amplitude compensator 1 5 3—1 to 1 5 3—4 calculates the “sum of the square of the distance from the X axis of the point above the X axis” for only the points to the right of the axis Y. Take the absolute value of the difference (Z) between the sum of the squares of the distances from the X axis of the lower point of the X axis to the lower point of the X axis. In this case, it is determined which of the differences is smaller, and the smaller one is repeated.Or, if Z is positive, right rotation by Δ and if Z is negative, left rotation is repeated. Converge to the correct angle. Δ can be assured by reducing it to some extent.

However, in this case, it is possible to converge to a point inclined by 45 degrees 1) There is also a possibility that it converges, so to avoid it, forcibly rotate 22.5 degrees when it converges to some extent and converge again, etc. I do.

As described above, according to the receiving apparatus of the present embodiment, by compensating the phase so that the distance between the signal of each quadrant and the orthogonal coordinate axis of the signal point arrangement is equal, the coordinate of the signal can be changed to the symbol pattern. The signal can be converged to the coordinates, and the received signal can be detected without the need for a pilot signal.

In addition, the present invention can be applied to not only QPSK but also 16QAM and 64QAM. In any case, at the time of transmission, the sum of the squares of the coordinates of the axes X and Y of the symbols arranged in the four quadrants is equal, so that the receiver can use the convergence method to compensate for the phase shift. it can.

(Embodiment 3)

As shown in Fig. 6, the symbol distribution of the received signal is such that a large number of symbols are distributed in dark areas and a small number of symbols are distributed in light areas. In Embodiment 3, the phase / amplitude compensator 15 3—1 to 15 3—4 in FIG. 1 cuts the two-dimensional space of the symbol coordinates into a mesh, observes the histogram of the symbol in the mesh, Phase and amplitude are compensated by assuming that the large coordinates of the histogram are the positions of the symbol pattern. FIG. 7 is a diagram illustrating an example of a histogram. In FIG. 7, the horizontal axis represents the I axis, and the vertical axis represents the Q axis. The numbers indicate the number of observed symbols. The phase 'amplitude compensator 1 5 3-1 to 1 5 3-4 estimates the coordinates of the large histogram, that is, the coordinates where the histogram is the maximum "1 0", as the coordinates of the symbol, the symbol pattern at transmission, For example, the phase and the amplitude are compensated so that the coordinates become symbols 201, 202, 203 and 204 in FIG.

After that, the phase / amplitude compensator 15 3-1 to 15 3-4 uses the convergence method of the second embodiment.

As described above, according to the receiving apparatus of the present embodiment, by compensating for the phase and amplitude of the symbol pattern with the coordinates of the most distributed symbol as the coordinates of the signal, a pilot signal is not required, and detection of the received signal It can be performed. If the mesh spacing is widened, the frequency increases quickly, so detection is possible with a small number of samples, but the accuracy is rough. On the other hand, if the mesh is small, the system is good, but the frequency in each mesh does not increase so much and many samples are required. For this reason, it is possible to improve the trade-off between accuracy and the required number of samplers by switching to a finer mesh after rough estimation with an initial mesh or smoothing in two dimensions.

(Embodiment 4)

In the fourth embodiment, the received signal is passed through an adaptive filter, the filter output is provisionally determined by the determination method described in the first embodiment, and the tap coefficient of the filter is adaptively reduced so that the error between the filter output and the filter output is reduced. An example in which is corrected will be described. FIG. 8 is a block diagram showing a configuration of a receiving apparatus according to Embodiment 4 of the present invention. However, components having the same configuration as in FIG. 1 are assigned the same reference numerals as in FIG. 1, and detailed description is omitted.

The receiving device 800 in FIG. 8 includes an adaptive filter 801, a selector 802, a subtractor 803, and an adaptive controller 804, and a signal after using the adaptive filter. From It differs from the receiver in Fig. 1 in that it creates a candidate signal, makes a decision, and corrects the adaptive filter based on the decision result.

Radio receiving section 151 receives the signal to which the pilot signal transmitted from transmitting apparatus 100 is not attached, and outputs the received signal to adaptive filter 81. The adaptive filter 801 adaptively modifies the tap coefficients of the filter according to the instruction of the adaptive controller 804. Then, adaptive filter 800 1 passes the signal output from radio receiving section 151 through the corrected filter, and outputs the result to channel estimation candidate generator 152 and subtractor 803.

The selector 802 selects a candidate signal in which no error is detected from among the candidate signals output from the error detectors 155-1-1 to 55_4 as a correctly demodulated signal. Then, the selector 802 outputs the selected candidate signal to the subtractor 803.

The subtractor 803 subtracts the signal output from the adaptive filter 801 with the candidate signal selected by the selector 802, and outputs the subtraction result to the adaptive controller 804. The adaptive controller 804 instructs the adaptive filter 801 to modify the tap coefficient of the filter so that the subtraction result approaches “0”. This operation may be repeated several times to improve accuracy.

As described above, according to the receiving apparatus of the present embodiment, the appropriate received signal is passed through the adaptive filter, and the filter output is provisionally determined by the determination method described in Embodiment 1, and the error between the filter output and the filter output is reduced. As described above, by adaptively correcting the tap coefficients of the filter, it is possible to detect the received signal without requiring a pilot signal.

At the time of the judgment by the selector 802, especially in the case of 16QAM or 64QAM, the threshold value in the amplitude direction of the judgment can be determined based on the power of the received signal.

In the above description, the case where QPSK is used as the modulation method is described as an example. However, the modulation method is not limited, and BPSK :, 8 PSK :, 16 QAM, and 64 Applicable to Q AM and deviation.

In addition, the present study is not limited to the above embodiment, and can be implemented with various changes. For example, in the above embodiment, the case of performing as a receiving apparatus has been described. However, the present invention is not limited to this, and the blind receiving method can be performed as software.

For example, a program for executing the blind receiving method may be stored in a ROM (Read Only Memory) in advance, and the program may be operated by a CPU (Central Processor Unit).

In addition, a program for executing the above blind receiving method is stored in a computer-readable storage medium, and the program stored in the storage medium is recorded in a RAM (Random Access Memory) of a computer, and the computer is executed by the computer. May be operated in accordance with.

As is clear from the above description, according to the receiving apparatus and the blind receiving method of the present invention, a plurality of candidate signals whose phases are changed by a phase difference between symbol patterns are generated from a received signal, and the candidate signals are generated. By selecting a signal in which no error has occurred from the demodulated result as a correctly received signal, detection of the received signal can be performed without the need for a pilot signal. The present specification is based on Japanese Patent Application No. 2002-287332 filed on September 30, 2002. This content is included here. Industrial applicability

INDUSTRIAL APPLICABILITY The present invention is suitable for use in a communication device, a communication terminal device, and a base station device.

Claims

The scope of the claims

1. Receiving means for receiving a radio signal, estimation candidate generating means for generating a plurality of estimation candidate signals by rotating the phase of a received non-I signal by a phase difference between symbol patterns, and Compensating means for compensating for the phase and amplitude of the symbol pattern; decoding means for error-correcting and decoding the compensated estimated candidate signal; detecting means for detecting an error from the error-corrected decoded estimated candidate signal; Selecting means for selecting the estimated candidate signal not received as received data.

2. The compensation means according to claim 1, wherein the compensation means compensates the phase so that the distance between the signal in each quadrant and the axis of the orthogonal coordinates of the signal point arrangement is equal.

3. The compensation means according to claim 1, wherein the compensation means observes the coordinates of a plurality of signals, and compensates for the phase and amplitude of the symbol pattern with the coordinates of the most distributed coordinates as the coordinates of the signals. Receiver.

4. An adaptive filter means for changing the phase of the received signal and outputting it to the estimation candidate generating means, and a phase change of the filter means so as to eliminate a phase difference between the signal selected by the selecting means and the received signal. The adaptive control means for controlling the amount, wherein the selecting means sets the signal selected when the phase difference has disappeared as a signal which can be correctly received. The receiving device according to the above.

5. On the transmitting side, transmit the signal without including the known signal, and on the receiving side, rotate the phase of the received radio signal by the phase difference between symbol patterns to create a plurality of estimated candidate signals, and perform estimation. The candidate signal is compensated for the phase and amplitude of the closest symbol pattern, the compensated estimated candidate signal is error-corrected decoded, and an error is detected from the error-corrected decoded estimated candidate signal. A blind reception method characterized by selecting the following as reception data.