JP3588092B2 - Receiving device and blind receiving method - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a receiving device and a blind receiving method.
[0002]
[Prior art]
Data transmission methods include synchronous detection and delay detection. Synchronous detection provides better performance compared to differential detection by notifying the pilot of the phase and amplitude of the signal using a pilot.
[0003]
In addition, a pilot is indispensable for maximum ratio combining of diversity, combined hybrid ARQ, RAKE reception of CDMA, and the like. Therefore, in synchronous detection, an overhead called a pilot is always required.
[0004]
Also, in the delay detection, the first symbol is used as a reception reference, and thus becomes an overhead. Furthermore, if pilots are inserted in a time-division manner, the frequency of insertion is considerably increased depending on the speed of line fluctuation, further increasing overhead.
[0005]
As a method of blind reception, there is a method described in Patent Document 1. However, in this method, although the phase shift of the carrier signal can be blindly compensated, it cannot be determined which of the symbol patterns the modulated signal corresponds to.
[0006]
[Patent Document 1]
JP-A-11-355188
[Problems to be solved by the invention]
As described above, in the conventional device, a pilot signal is required to detect a received signal, and there is a problem that the transmission capacity is reduced and the throughput is reduced by the amount of transmitting the pilot signal.
[0008]
The present invention has been made in view of the above, and 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.
[0009]
[Means for Solving the Problems]
The receiving apparatus of the present invention includes a receiving unit that receives a radio signal, an estimation candidate generating unit that rotates the phase of the received radio signal by all phase differences between symbol patterns to generate an estimation candidate signal for the symbol pattern. Compensating means for compensating each estimated candidate signal to the phase and amplitude of the closest symbol pattern; decoding means for error-correcting and decoding each compensated estimated candidate signal; and detecting means for detecting an error from the error-corrected decoded estimated candidate signal. And a selecting means for selecting, as received data , an error correction decoding result of the estimation candidate signal in which no error has occurred.
[0010]
According to this configuration, a candidate signal in which a phase is changed from a received signal to a phase difference between symbol patterns is created, and a signal in which no error has occurred in a result of demodulating the candidate signal is selected as a correctly received signal. By doing so, it is possible to detect a received signal without requiring a pilot signal.
[0011]
Receiving apparatus of the present invention, the compensation means, a configuration in which the distance between the axes of orthogonal coordinates of the signal point arrangement for each quadrant of the signal to compensate for the phase to be equal.
[0012]
According to this configuration, by compensating the phase so that the distance between the signal of each quadrant and the axis of the orthogonal coordinates of the signal point arrangement is equal, the coordinates of the signal can be made to converge to the coordinates of the symbol pattern. Detection of a received signal can be performed without requiring a signal.
[0013]
The receiving device of the present invention employs a configuration in which the compensating means observes the coordinates of a plurality of signals and compensates for the phase and amplitude of the symbol pattern using the coordinates of the most distributed coordinates as the coordinates of the signals.
[0014]
According to this configuration, the received signal can be detected without the need for a pilot signal by compensating for the phase and amplitude of the symbol pattern with the coordinates of the most distributed coordinates as the coordinates of the signal.
[0015]
The receiving apparatus according to the present invention comprises: an adaptive filter means for changing a phase of a received signal and outputting the same to the estimation candidate generating means; and the filter means for eliminating a phase difference between the signal selected by the selecting means and the received signal. And an adaptive control means for controlling the amount of phase change, and the selecting means adopts a configuration in which the signal selected when the phase difference disappears becomes a signal that can be correctly received.
[0016]
According to this configuration, the pilot signal is required by passing the appropriate reception signal through the adaptive filter, tentatively determining the filter output, and adaptively correcting the tap coefficient of the filter so that the error between the filter output and the filter output is reduced. Instead, it is possible to detect the received signal.
[0017]
In the blind receiving method of the present invention, the phase of the received radio signal is rotated by all the phase differences between the symbol patterns to generate estimated candidate signals for the symbol patterns, and each estimated candidate signal is compared with the phase of the closest symbol pattern. Error-decoding is performed on each of the compensated estimated candidate signals, an error is detected from the error-corrected decoded estimated candidate signals, and an error-correction decoding result of the estimated candidate signal having no error is selected as received data. I did it.
[0018]
According to this method, a candidate signal in which the phase is changed to a phase difference between symbol patterns from a received signal is created, and a signal in which no error has occurred in a result of demodulating the candidate signal is selected as a correctly received signal. By doing so, it is possible to detect a received signal without requiring a pilot signal.
[0019]
BEST MODE FOR CARRYING OUT THE INVENTION
The gist of the present invention is to generate a plurality of candidate signals whose phases are 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. That is, detection of a received signal is performed without selecting a pilot signal as a selected signal.
[0020]
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0021]
(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 transmission apparatus 100 in FIG. 1 mainly includes an error correction bit addition section 101, an error correction encoder 102, a modulator 103, and a radio transmission section 104.
[0022]
Error correction bit adding section 101 adds error correction bits to the transmission data and outputs the result to error correction encoder 102. Error correction encoder 102 performs error correction encoding on the transmission data and outputs the result to modulator 103. Modulator 103 modulates transmission data and outputs the result to wireless transmission section 104. In this embodiment, an example in which QPSK modulation is performed will be described.
[0023]
Radio transmitting section 104 converts the frequency of the transmission data from a baseband frequency to a radio frequency, and transmits the converted signal to a communication partner. A pilot signal serving as a reference for compensating the phase and amplitude is not added to the transmission data transmitted here.
[0024]
The transmission data to which the pilot signal is not added is blindly received on the receiving side. 1 includes a radio receiving section 151, a channel estimation candidate generator 152, phase / amplitude compensators 153-1 to 153-4, error correction decoders 154-1 to 154-4, It mainly comprises error detectors 155-1 to 155-4 and a selector 156.
[0025]
Radio receiving section 151 receives a signal to which a pilot signal has not been added, transmitted from transmitting apparatus 100, and outputs the received signal to channel estimation candidate generator 152.
[0026]
Channel estimation candidate generator 152 creates a candidate signal in which the phase of the signal is changed by the phase difference between the symbol patterns, and outputs it to phase / amplitude compensators 153-1 to 153-4.
[0027]
The phase / amplitude compensator 153-1 compensates the phase and amplitude of the candidate signal to a symbol pattern having the closest phase and amplitude, and outputs the candidate signal to the error correction decoder 154-1. Similarly, the phase / amplitude compensators 153-2 to 153-4 also compensate for the phase and amplitude of the candidate signal in the same manner as the phase / amplitude compensator 153-1 and respectively perform error correction decoders 154-2 to 154-4. Output to
[0028]
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, error correction decoders 154-2 to 154-4 perform error correction decoding on the candidate signal whose phase and amplitude have been compensated, and output the result to error detectors 155-2 to 155-4.
[0029]
Error detector 155-1 determines whether or not the candidate signal is incorrect, and outputs the candidate signal and the determination result to selector 156. Similarly, error detectors 155-2 to 155-4 determine whether or not the candidate signal is incorrect, and output the candidate signal and the determination result to selector 156.
[0030]
The selector 156 selects a candidate signal in which no error is detected as a correctly demodulated signal.
[0031]
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. 2, the horizontal axis represents the I axis, and the vertical axis represents the Q axis. On the transmitting side, the four types of data are mapped to any of the symbols 201, 202, 203, and 204 and transmitted.
[0032]
However, due to the influence of a propagation path such as fading, the receiving side receives the symbol in a state where the phase and amplitude of the symbol have changed. FIG. 3 is a diagram illustrating an example of a symbol pattern of a received QPSK modulation signal. The horizontal axis indicates the I axis, and the vertical axis indicates the Q axis. As shown in FIG. 3, the phase of the symbol 301 changes.
[0033]
For example, in the symbol 301, the symbol 201 in FIG. 2 has the phase advanced by 20 degrees, the symbol 204 has the phase advanced by 110 degrees, the symbol 203 has the phase advanced by 200 degrees, and the symbol 202 has the phase advanced by 290 degrees. One of those. 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.
[0034]
Therefore, the channel estimation candidate generator 152 changes the phase of the received signal by 0, 90, 180, and 270 degrees. Then, 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 301 shown in FIG. 3, the phase / amplitude compensator 153-1 returns the phase by 20 degrees.
[0035]
Similarly, the phase / amplitude compensator 153-2 compensates for the phase and amplitude of the signal whose phase has been changed by 90 degrees. The phase / amplitude compensator 153-3 compensates for the phase and amplitude of the signal whose phase has been changed by 180 degrees. Then, the phase / amplitude compensator 153-4 compensates for the phase and amplitude of the signal whose phase has been changed by 270 degrees.
[0036]
Then, the signal whose phase has been changed by 0 degree is subjected to error correction decoding in error correction decoder 154-1, and error detector 155-1 determines whether or not there is an error.
[0037]
Similarly, the signals whose phases are changed by 90 degrees, 180 degrees, and 270 degrees are subjected to error correction decoding in error correction decoders 154-2 to 154-4, and error detectors 155-2 to 155-155. At 4, it is determined whether there is an error.
[0038]
Then, demodulation and decoding are performed assuming that the received signal is located at any one of the four types of QPSK modulation symbols. As a result of the decoding, a signal on which no error is detected is selected as a correct signal.
[0039]
Thus, if there is no noise, as is clear from the above figure, if QPSK, even one point is observed, and its phase and four types obtained by adding 0, 90, 180, and 270 degrees to each point are obtained. What is necessary is just to be a candidate.
[0040]
When there is noise, an observation result as shown in FIG. 4 or FIG. 5 is obtained. 4 and 5 are diagrams illustrating an example of a symbol pattern of a received QPSK modulation signal. In the examples of FIGS. 4 and 5, symbols are dispersed by noise, and correct channel estimation cannot be performed with only one point. Therefore, it is necessary to observe at several points (the channel can be estimated with fairly good accuracy by looking at all the symbols of one packet).
[0041]
In the case of 8PSK, 16QAM, 64QAM, etc., similarly, a unique number of uncertainties are allowed, a candidate signal is generated on the assumption that the phase and the amplitude have changed by the number of symbol types, and decoding of these candidate signals is performed. If an error is not detected in the result, demodulation is possible without a pilot.
[0042]
As described above, according to the receiving apparatus of the present embodiment, an error is generated in a result of generating a candidate signal in which a phase is changed from a received signal to a phase difference between symbol patterns and demodulating the candidate signal. By selecting a missing signal as a correctly received signal, it is possible to detect a received signal without requiring a pilot signal.
[0043]
(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 showing 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).
[0044]
First, if the QPSK reception signal is not inclined due to the influence of the line, the distribution of the points above the axis X and the points below the axis X should be targeted in the region to the right of the axis Y. However, in FIG. 6, it can be seen that the distribution is biased at a position above the axis X further away from the axis X because the distribution is inclined due to fading or the like.
[0045]
The phase / amplitude compensators 153-1 to 153-4 in FIG. 1 observe the coordinates of a plurality of symbols. For example, all symbols of one packet are observed.
[0046]
Then, the phase / amplitude compensators 153-1 to 153-4 provide the "sum of the square of the distance of the upper point on the X axis from the X axis" and "X axis The sum of the square of the distance of the lower point from the X-axis ”is calculated, and either the case where the rotation is counterclockwise by a certain rotation angle Δ or the case where the rotation is clockwise is Judgment is made as to whether the difference is small, and selection of the smaller one is repeated, or if Z is positive, right rotation by Δ and if Z is negative, left rotation is repeated to converge to the correct angle. The accuracy can be ensured by reducing Δ to some extent.
[0047]
However, in this case, there is a possibility of convergence to a point inclined by 45 degrees. In order to avoid this, when the convergence has been made to some extent, forcible rotation is performed by 22.5 degrees and convergence is performed again.
[0048]
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 axis of the orthogonal coordinates of the signal point arrangement is equal, the coordinate of the signal is changed to the symbol pattern. It is possible to converge to the coordinates, and it is possible to detect a received signal without requiring a pilot signal.
[0049]
In addition, the present invention is not limited to QPSK, and can be applied to 16QAM, 64QAM, and the like. 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. Therefore, the use of the convergence method on the receiving side can compensate for the phase shift.
[0050]
(Embodiment 3)
In the symbol arrangement of the received signal, as shown in FIG. 6, many symbols are distributed in dark portions, and few symbols are distributed in light portions. In the third embodiment, the phase / amplitude compensators 153-1 to 153-4 of FIG. 1 cut a two-dimensional space of symbol coordinates into a mesh, observe a histogram in the mesh, and convert a coordinate having a large histogram into a symbol pattern. To compensate for phase and amplitude.
[0051]
FIG. 7 is a diagram illustrating an example of a histogram. 7, the horizontal axis indicates the I axis, and the vertical axis indicates the Q axis. The numbers indicate the number of the observed symbols.
[0052]
The phase / amplitude compensators 153-1 to 153-4 estimate the large coordinates of the histogram, that is, the coordinates where the histogram is the maximum "10", as the coordinates of the symbol, and transmit the symbol pattern at the time of transmission, for example, the symbol of FIG. The phase and amplitude are compensated so that the coordinates become 201, 202, 203 and 204.
[0053]
After that, the phase / amplitude compensators 153-1 to 153-4 use the convergence method of the second embodiment.
[0054]
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 coordinates as the coordinates of the signal, the pilot signal is not required, and the detection of the received signal can be performed. It can be carried out.
[0055]
(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 adjusted so that the error between the filter output and the filter output is reduced. An example of correction will be described.
[0056]
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 denoted by the same reference numerals as in FIG. 1, and detailed description is omitted.
[0057]
The receiving apparatus 800 in FIG. 8 includes an adaptive filter 801, a selector 802, a subtractor 803, and an adaptive controller 804, generates a candidate signal from a signal after using the adaptive filter, and makes a determination. 1 in that the adaptive filter is modified based on the determination result.
[0058]
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 adaptive filter 801.
[0059]
The adaptive filter 801 adaptively modifies the tap coefficients of the filter according to the instruction of the adaptive controller 804. Then, adaptive filter 801 passes the signal output from radio reception section 151 through the modified filter, and then outputs the result to channel estimation candidate generator 152 and subtractor 803.
[0060]
The selector 802 selects, from among the candidate signals output from the error detectors 155-1 to 155-4, a candidate signal in which no error is detected as a correctly demodulated signal. Then, the selector 802 outputs the selected candidate signal to the subtractor 803.
[0061]
The subtractor 803 subtracts the signal output from the adaptive filter 801 with the candidate signal selected by the selector 802, and outputs the result of the subtraction to the adaptive controller 804.
[0062]
Adaptive controller 804 instructs 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 the accuracy.
[0063]
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, so that the error between the filter output and the filter output is reduced. In addition, by adaptively modifying the tap coefficients of the filter, it is possible to detect a received signal without requiring a pilot signal.
[0064]
At the time of the determination by the selector 802, especially in 16QAM or 64QAM, the threshold value in the amplitude direction of the determination can be determined based on the power of the received signal.
[0065]
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 can be applied to any of BPSK, 8PSK, 16QAM, and 64QAM.
[0066]
Further, the present invention is not limited to the above embodiment, and can be implemented with various modifications. For example, in the above-described 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.
[0067]
For example, a program for executing the blind reception method may be stored in a ROM (Read Only Memory) in advance, and the program may be operated by a CPU (Central Processor Unit).
[0068]
Further, a program for executing the 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 the computer, and the computer is operated according to the program. You may make it do.
[0069]
【The invention's effect】
As described above, 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 from a received signal are generated, and a result of demodulating the candidate signals By selecting a signal in which no error has occurred among the signals as a correctly received signal, it is possible to detect a received signal without requiring a pilot signal.
[Brief description of the drawings]
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 a QPSK modulation scheme. FIG. 3 is a symbol of a received QPSK modulation scheme signal. FIG. 4 shows an example of a symbol pattern of a received QPSK modulation scheme signal. FIG. 5 shows an example of a symbol pattern of a received QPSK modulation scheme signal. FIG. 7 shows an example of a symbol pattern of a QPSK modulation signal. FIG. 7 shows an example of a histogram. FIG. 8 is a block diagram showing a configuration of a receiving apparatus according to a fourth embodiment of the present invention.
101 Error Correction Bit Adder 102 Error Correction Encoder 103 Modulator 104 Radio Transmitter 151 Radio Receiver 152 Channel Estimation Candidate Generators 153-1 to 153-4 Phase and Amplitude Compensators 154-1 to 154-4 Error Correction Decoders 155-1 to 155-4 Error detector 156 Selector 801 Adaptive filter 802 Selector 803 Subtractor 804 Adaptive controller

Claims (5)

Most receiving means for receiving radio signals, and estimating candidate generating means for generating an estimated candidate signal symbol pattern amount the phase of the received radio signal to rotate in all of the phase difference between symbol patterns, each estimated candidate signal Compensating means for compensating for the phase and amplitude of a close symbol pattern, decoding means for performing error correction decoding of each compensated estimated candidate signal, detecting means for detecting an error from the error corrected decoded estimated candidate signal, and no error Selecting means for selecting the error correction decoding result of the estimated candidate signal as received data. 2. The receiving apparatus according to claim 1, wherein the compensating means compensates the phase so that a distance between a signal in each quadrant and an axis of orthogonal coordinates of a signal point arrangement is equal. 3. The reception device according to claim 1, wherein the compensating unit observes coordinates of a plurality of signals, and compensates for the phase and amplitude of the symbol pattern using the coordinates of the most distributed coordinates as the coordinates of the signals. 4. apparatus. Adaptive filter means for changing the phase of a received signal and outputting the result to the estimation candidate generating means; and controlling the amount of phase change of the filter means so as to eliminate the phase difference between the signal selected by the selecting means and the received signal. 4. An adaptive control unit, wherein the selection unit sets the selected signal as a signal that can be correctly received when the phase difference disappears. Receiving device. The phase of the received radio signal is rotated by all the phase differences between the symbol patterns to generate estimated candidate signals for the symbol patterns, each estimated candidate signal is compensated to the phase and amplitude of the closest symbol pattern, and each compensated A blind reception method comprising: performing error correction decoding of an estimated candidate signal; detecting an error from the error corrected decoded estimated candidate signal ; and selecting, as reception data , an error correction decoding result of the estimated candidate signal in which no error has occurred. .

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