JP4854091B2 - COMMUNICATION SYSTEM, RECEPTION DEVICE, AND COMMUNICATION METHOD - Google Patents

Description

  The present invention relates to a communication system, a receiving apparatus, and a communication method.

  Error correction codes such as convolutional codes and turbo codes are used to correct errors that occur when data is transmitted. The error correction capability of the error correction code is represented by a coding rate. The coding rate R is generally expressed as a ratio of the number of information bits m to the number of encoded bits n, R = m / n, and as R decreases, the correction capability of the error correction code improves. Since the number of redundant bits (number of parity bits) increases, the transmission efficiency deteriorates.

A puncturing technique is known in which coded bits are thinned out to set a certain desired coding rate. The puncturing in the turbo code will be described. Since a turbo encoder normally used outputs an information bit sequence b, a first parity bit sequence p ₁ , and a second parity bit sequence p ₂ , a code with a coding rate of 1/3 is used. A bit sequence c is generated. Assuming that the information bit length is N, b, p ₁ , p ₂ , and c are expressed by the following equations (1) to (4).

By puncturing the coded bit sequence c having the coding rate 1/3, the coding rate of the error correction code can be changed. In order to generate a coding rate 1/2 sequence, for example, p _1,2m and p _2,2m-1 may be thinned out from c. However, m is an integer of 1 to N / 2.
For example, in the case of N = 2, the sequence of the coding rate 1/3 is [b ₁ , p ₁ , ₁ , p ₂ , ₁ , b ₂ , p ₁ , ₂ , p ₂ , ₂ ]. When a puncturing is performed to generate a coding rate ½ sequence, [b ₁ , p _1,1 , b ₂ , p _2,2 ] is obtained.

In this case, p _2,1 and p _1,2 are punctured. Here, assuming that data having a coding rate of ½ is transmitted, a bit sequence having a coding rate of ½ on the receiving device side is represented as [x ₁ , y _1,1 , x ₂ , y _2,2 ]. Can do.
Here, x ₁ , y _1,1 , x ₂ , y ₂ , ₂ are bit log likelihood ratios (LLRs) that are soft decision values, and information bits and parity bits obtained in the reception process, respectively. It corresponds to.

At this time, the receiving apparatus performs error correction decoding after performing depuncturing, which is a reverse process of puncturing. Depuncturing is performed by inserting a predetermined value, for example, 0, into the position of the punctured bit on the transmission device side.
That is, the bit sequence [x ₁ , y ₁ , ₁ , x ₂ , y ₂ , ₂ ] on the receiving device side is changed to [x ₁ , y ₁ , ₁ , 0, x ₂ , 0, y ₂ , ₂ ]. After depuncturing, error correction decoding processing is performed. An LLR of 0 indicates a state in which it is unknown whether the bit is 1 or 0.

Such a puncturing process and a depuncturing process are described in Patent Document 1, for example.
Thus, by performing the puncturing process on the transmission device side and the depuncturing process on the reception device side, the coding rate can be changed, and the transmission rate can be controlled.
JP 2000-68862 A

  However, the conventional technique has a problem in that error correction decoding performance deteriorates because a predetermined value or an indeterminate value such as 0 is inserted at the time of depuncturing in the receiving apparatus.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to prevent a deterioration in the performance of error correction decoding, and to improve the performance of reception performance. It is to provide a communication method.

(1) The present invention has been made in order to solve the above problems, and a communication system according to an aspect of the present invention is a communication system including a transmission device and a reception device, and the transmission device includes the reception device. A puncturing unit that performs puncturing processing to thin out a signal to be transmitted to the device, and a transmitting unit that transmits a signal punctured by the puncturing unit to the receiving device. The receiving device performs softening by performing demodulation processing. A demodulator that calculates a decision value; a depuncture unit that performs a depuncture process that inserts a soft decision value at a position of a signal that is thinned out by a puncture process when a signal is transmitted by the transmission device; and the depuncture unit performs a depuncture process. A decoding unit that performs error correction decoding processing on the performed signal, and a soft decision value included in the signal that has been subjected to error correction decoding processing by the decoding unit; And a receiving puncturing unit for obtaining the soft decision value of the position decimated during puncturing with the transmitting device, the depuncturing unit uses a soft-decision value in which the reception puncturing part is determined to de-puncturing.

(2) In addition, a receiving device according to an aspect of the present invention is a receiving device that communicates with a transmitting device, a demodulator that calculates a soft decision value by performing demodulation processing, and a signal transmitted by the transmitting device. A depuncture unit that performs depuncture processing to insert a soft decision value at the position of the signal thinned out by puncture processing, and a decoding unit that performs error correction decoding processing on the signal that has been depunctured by the depuncture unit, A reception puncturing unit for obtaining a soft decision value at a position thinned out during puncturing processing in the transmission device among soft decision values included in a signal subjected to error correction decoding processing by the decoding unit, and the depuncturing unit includes: The soft decision value obtained by the reception puncture unit is used for the depuncture process.

(3) In addition, the reception device according to an aspect of the present invention further includes an interference replica generation unit, a subtraction unit, a signal detection unit, and a propagation path estimation unit, and the reception puncture unit is a position where the transmission device thins the signal. The interference replica generation unit generates a replica of an interference signal based on the soft decision value punctured by the reception puncture unit, and the subtraction unit receives the soft decision value The replica of the interference signal is subtracted from the signal to remove the interference, the signal detection unit performs signal detection on the signal after the interference removal, and the demodulation unit performs signal detection on the signal detection unit. The received signal is demodulated.

(4) In addition, the depuncturing unit of the receiving device according to one aspect of the present invention performs the depuncturing process of the soft decision value only in the last round of the iterative process.

(5) Further, a communication method according to an aspect of the present invention is a communication method using a reception device that communicates with a transmission device, wherein a demodulation process for calculating a soft decision value by performing a demodulation process, and the transmission device A depuncture process for performing a depuncture process for inserting a soft decision value at a position of a signal thinned out by a puncture process at the time of transmission of a signal by the puncture process, and an error correction decoding process for the signal that has undergone the depuncture process in the depuncture process A decoding process and a reception puncturing process for calculating a soft decision value at a position thinned out during the puncturing process in the transmitting device among the soft decision values included in the signal subjected to the error correction decoding process in the decoding process. In the depuncture process, the soft decision value obtained in the reception puncture process is used for the depuncture process.

  According to the communication system, the receiving apparatus, and the communication method of the present invention, it is possible to prevent the performance of error correction decoding from being deteriorated and to improve the performance of the reception performance.

(First embodiment)
First, a communication system according to the first embodiment of the present invention will be described. This communication system includes a transmission device 100a and a reception device 200a.

FIG. 1 is a schematic block diagram showing a configuration of a transmission device 100a according to the first embodiment of the present invention. The transmitting apparatus 100a includes a coding unit 1, a puncturing unit 2, a modulation unit 3, a pilot multiplexing unit 4, a radio unit 5, and an antenna unit 6.
The information bits are subjected to error correction coding by the convolution code, turbo code, LDPC (Low Density Parity Check) code or the like in the coding unit 1.

The puncturing unit 2 thins out the bits from the bit sequence that is output from the encoding unit 1 and outputs the bit sequence to the modulation unit 3 in order to obtain a given coding rate and bit rate. Here, a case where turbo coding is performed will be described.
In the following embodiments, a case where a turbo code is used will be described. However, the present invention is not limited to the case where a turbo code is used, and the communication system using other error correction codes such as a convolutional code and an LDPC code is also used. Applicable.

Let c be the output bit sequence of the encoding unit 1 when the turbo code is used. The bit sequence c is expressed as the following equations (5) to (8) using the information bit sequence b, the first parity bit sequence p ₁ , and the second parity bit sequence p ₂ .

At this time, the coding rate of c is 1/3. c is input to the puncturing unit 2 and subjected to a puncturing process. For example, when a code rate 1/2 sequence is generated by _puncturing , p _1,2m and p _2,2m-1 may be thinned out from c. However, m is an integer of 1 to N / 2.

The modulation unit 3 maps the input bit sequence to modulation symbols such as QPSK (Quadrature Phase Shift Keying) and 16QAM (16 Quadrature Amplitude Modulation), and the pilot multiplexing unit 4 multiplexes pilot signals.
The radio unit 5 performs D / A (Digital to Analog) conversion of the input signal, shapes the waveform with a transmission filter (not shown), converts it to radio frequency conversion, and transmits the radio signal from the antenna unit 6 to the receiving device. To do.

FIG. 2 is a schematic block diagram showing the configuration of the receiving device 200a according to the first embodiment of the present invention. The receiving apparatus 200a includes an antenna unit 7, a radio unit 8, a propagation path estimation unit 9, a propagation path compensation unit 10, a demodulation unit 11, a storage unit 15, a depuncture unit 12, a decoding unit 13, and a reception puncture unit 14.
The receiving device 200a receives a reception signal with the antenna unit 7, the radio unit 8 converts a radio frequency into a baseband signal, shapes a waveform with a reception filter (not shown), and performs A / D (Analog to Digital). (Digital) conversion.

Then, the propagation path estimation unit 9 performs propagation path estimation using the pilot signal, the propagation path compensation unit 10 performs propagation path compensation based on the propagation path estimation value, the demodulation unit 11 performs demodulation processing, and the soft decision value A bit LLR (Log Likelihood Ratio) is calculated.
The bit LLR calculated by the demodulation unit 11 is stored in the storage unit 15. The depuncturing unit 12 inserts the bit LLR stored in the storage unit 15 at the bit position thinned out by the puncturing unit 2 of the transmission device 100a, and the decoding unit 13 performs error correction decoding processing.

  If there is no error in the information bits obtained by the decoding process, the information bits are output and the reception process is terminated. On the other hand, if an error is detected, the bit LLR is output to the reception puncturing unit 14. However, when the decoding process has never been performed, a fixed value such as 0 is output to the reception puncturing unit 14.

The LLR of an input to the decoder 13 the coded bit _{c n} and L _{(c n),} the output bit LLR of the decoder 13 of coding bits _{c n} and _L D _{(c n).} N represents the number of encoded bits, and n is an integer satisfying 1 ≦ n ≦ N. L _D (c _n ) can be obtained using L (c ₁ ) to L (c _N ), and the decoding unit 13 calculates L _D (c _n ) according to the following equation (9), for example, The data is output to the reception puncturing unit 14.

Where P (x) represents the probability of x occurring and P (x | y) represents the probability of x occurring when y occurs (conditional probability). P (c _n = + 1 | L (c ₁ ),..., L (C _N )) in the formula (9) is, for example, when L (c ₁ ) to L (c _N ) are given. It is obtained by obtaining a metric (distance) _where c _n = + 1.

The bit LLR output from the decoding unit 13 is an LLR before puncturing on the transmission device side, and is configured by an LLR of information bits and an LLR of parity bits. Bits with 0 inserted at the time of depuncturing are also output with likelihood. That is, the value of LLR is not zero.
The bit LLR output from the decoding unit 13 is input to the reception puncturing unit 14. The reception puncture unit 14 extracts the bit LLR thinned out on the transmission device 100 a side from the input bit LLR and outputs the extracted bit LLR to the depuncture unit 12.

When the error correction decoding process is performed in the decoding unit 13, the likelihood is calculated from other bits having a value even if the decoding process has never been performed and even if it is depunctured with 0. The depunctured bits also have a likelihood.
Therefore, decoding performance is improved by depuncturing using the likelihood obtained by the decoding process rather than inserting a fixed value.

FIG. 3 is a flowchart showing processing of the receiving device 200a according to the first embodiment of the present invention. The flowchart shown in FIG. 3 starts when a signal is read from the storage unit 15. In step S101, the output in step S104 is depunctured with respect to the demodulated bit LLR.
Error correction decoding processing is performed on the depunctured bit LLR in step S102. In step S103, it is determined whether or not an error is detected in the result of the decoding process, or whether the specified number of processes has been reached. If no error is detected or the specified number of processes has been reached, an information bit is output and the process of the flowchart of FIG. 3 is terminated.

If there is an error, the coded bit LLR is output to the reception puncturing unit 14. In step S104, among the encoded bit LLRs obtained by the decoding process, the bit LLR punctured on the transmitting device 100a side is output. In step S101, the depuncture process is performed again.
The depuncture process is performed on the demodulated bit LLR stored in the storage unit 15. After depuncturing, the decoding process is performed in step S102, and when an error is detected, the processes of step S104, step S101, and step S102 are performed again.

In the transmission device 100a of the communication system according to the first embodiment of the present invention, the puncture unit 2 performs puncturing processing for thinning out a signal to be transmitted to the reception device 200a, and the signal subjected to the puncture processing by the puncture unit 2 is transmitted to the reception device 200a. Radio section 5 (also referred to as a transmission section) transmits.
In addition, in the receiving device 200a of the communication system according to the first embodiment of the present invention, the demodulation unit 11 calculates a soft decision value by performing demodulation processing, and is thinned out by puncturing processing when a signal is transmitted by the transmitting device 100a. The depuncture unit 12 performs depuncture processing to insert a soft decision value at the position of the received signal, the decoding unit 13 performs error correction decoding processing on the signal that the depuncture unit 12 has performed depuncture processing, and the decoding unit 13 Of the soft decision values included in the signal subjected to the correction decoding process, the reception puncture unit 14 obtains the soft decision values at the positions thinned out during the puncture processing in the transmission device 100a.
Further, the depuncture unit 12 of the reception device 200a according to the first embodiment of the present invention uses the soft decision value obtained by the reception puncture unit 14 for the depuncture process.

  In the first embodiment of the present invention described above, puncture processing is performed by the receiving apparatus 200a by the transmitting apparatus 100a by performing error correction decoding processing on the receiving apparatus 200a side even for data that has not been transmitted from the transmitting apparatus 100a by puncturing processing. By calculating the soft decision value of the received data and using the soft decision value for the depuncture process and performing the error correction decoding process again, the reception performance of the receiving apparatus 200a can be improved.

(Second Embodiment)
Next, a communication system according to the second embodiment of the present invention will be described. This communication system includes a transmission device 100b and a reception device 200b. In the second embodiment, a case where the present invention is applied to a MIMO (Multiple Input Multiple Output) system will be described.

FIG. 4 is a schematic block diagram showing the configuration of the transmission device 100b according to the second embodiment of the present invention. Transmitting apparatus 100b includes encoding units 1-1 to 1-N _T (N _T is an integer of 2 or 2), puncturing units 2-1 to 2-N _T , modulation units 3-1 to 3-N _T , GI (Guard Interval) insertion units 33-1 to 33-N _T , pilot multiplexing units 4-1 to 4-N _T , radio units 5-1 to 5-N _T , and antenna units 6-1 to 6- _NT is provided.

The transmission device 100b according to the second embodiment transmits independent signals from _NT transmission antennas to the reception device 200b using the same timing and the same frequency. That, _{N T} sets of information bits, _{N T} sets of code section 1-1, ..., are respectively error correction coding with _{1-N T.} Puncturing section 2-1, ..., the _{2-N T,} code section 1-1, ..., for the bit sequence, which is the output of the _{1-N T,} for a given coding and bit rate , modulation section 3-1 by thinning out bits, and outputs the ··· _{3-N T.} Modulating unit 3-1, ... _{3-N T} maps the input bit sequence to modulation symbols, GI insertion section 33-1, ..., inserts a guard interval in _{33-N T.} The outputs of the GI insertion units 33-1,..., 33- _NT are multiplexed with pilot signals in the pilot multiplexing units 4-1,..., 4- _NT , and waveform-shaped in a transmission filter (not shown). Guided to the radio units 5-1,..., 5- _NT . Radio unit 5-1, ..., _{5-N T} converts the output of the transmit filter to the radio frequency, the antenna unit 6-1, ..., and transmits the _{6-N T.}
The receiving apparatus 200b according to the second embodiment repeatedly performs MIMO separation using the result of the error correction decoding process.

FIG. 5 is a schematic block diagram showing the configuration of the receiving device 200b according to the second embodiment of the present invention. Receiving device 200b includes an antenna unit _{7-1~7-N R} (N R is 2 or an integer of 2 or more), the radio unit 8-1 to _8-N R, GI removal unit 36-1 to _{36-N R} , Propagation path estimation unit 16, FFT (Fast Fourier Transform) units 26-1 to 26-N _R , signal detection unit 17, demodulation units 18-1 to 18-N _R , depuncture units 19-1 to 19 -N _R, the decoding unit 20-1 to _{20-N R,} receiving puncturing section 21 - 1 to _{21-N R,} and a symbol replica generating unit 22-1 to _{22-N R.}

Receiving device 200b is a signal that signals transmitted from _{N T} antennas portion 6-1 to _{6-N T} of the transmission device 100a side is spatially multiplexed, the _{N R} present antenna unit 7-1 through 7 -N _R Received.
Signals received by the respective antenna units 7-1 to _{7-N R} is converted from a radio frequency by the radio unit 8-1 to _{8-N R} into a baseband signal, to waveform shaping by the reception filter (not shown), A / D conversion is performed, is output to and channel estimation unit 16 GI removal unit 36-1 to _{36-N R.}

The propagation path estimation unit 16 performs propagation path estimation using the pilot signal, and outputs the propagation path estimation value to the signal detection unit 17.
GI removing section 36-1 to _{36-N R} removes the guard interval from the received signal, FFT unit 26-1 to _{26-N R} performs a time-frequency conversion, and outputs to the signal detection unit 17. The signal detecting section 17 by using the channel estimation value between the received signal and the bit LLR input, detects a signal transmitted from the antenna units 6-1 to 6-N _T of the transmission device 100b.

Demodulator 18-1 to _{18-N R} is the signal detecting unit 17 performs a demodulation process for each detected signal, and outputs the bit LLR to the de-puncturing unit 19 - 1 through _{19-N R.} Depuncturing section 19 - 1 through _{19-N R} is the signal output from the receiving puncturing section 21 - 1 to _{21-N R,} inserted into punctured position transmitting device 100b side.
Signal output from the depuncturing unit 19 - 1 through _{19-N R} is the decoding process by the decoding unit 20-1 to _{20-N R.} If the reception process has been performed a prescribed number of times, an information bit is output and the process ends. When the prescribed number of reception processes have not been performed, the bit LLR with the updated likelihood is output, and the process proceeds to a repetition process.

In the iteration, the received puncturing section 21 - 1 to _{21-N R} is the puncturing process at the same puncture pattern as the bit LLR to the decoding unit 20-1 to _{20-N R} has output was performed at the transmitting device 100b side Do.
Receiving puncturing section 21 - 1 to _{21-N R} outputs bit LLR subjected to puncturing processing on the symbol replica generation unit 22-1 to _{22-N R,} depuncturing section 19-1 bit LLR obtained by thinning the puncturing processing and outputs it to the _{~19-N R.}

FIG. 6 is a schematic block diagram illustrating a configuration of the signal detection unit 17 of the reception device 200b according to the second embodiment of the present invention. The signal detection unit 17 includes an interference replica generation unit 23, subtraction units 24-1 to 24-N _R , signal separation unit 25, IFFT (Inverse Fast Fourier Transform) units 27-1 to 27-N _R. I have.

Interference replica generation unit 23, a replica of an interference signal from the other antenna portion from the channel estimation value input from the channel estimator and symbol replicas generated by the symbol replica generating unit 22-1 to 22-N _R Generate.
Replica of the interference signal generated by the interference replica generation unit 23, interference cancellation is performed by being subtracted from the received signal by the subtraction unit 24-1 to 24-N _R. The signal separation unit 25 separates the spatially multiplexed signal from the signal after interference removal using MMSE (Minimum Mean Square Error) or the like, and the IFFT units 27-1 to 27-. N _R performs frequency time conversion.

FIG. 7 is a flowchart showing processing of the receiving device 200b according to the second embodiment of the present invention. First, the interference replica generated in step S208 is subtracted from the signal after FFT to remove interference (step S201).
MIMO signal detection is performed on the signal after interference removal (step S202). In step S203, a bit LLR is calculated by demodulation processing. In step S204, depuncture processing is performed. The bit LLR to be inserted when depuncturing is the puncture bit LLR obtained in step S207.

After the depuncture processing, error correction decoding processing is performed in step S205. If no error is detected in the result of the decoding process in step S206, or if the specified number of processes has been reached, the process of the flowchart in FIG. If an error is detected and the prescribed number of processes has not been reached, the process proceeds to step S207.
In step S207, among the encoded bit LLR obtained by the decoding process, the bit LLR at the position thinned out by the puncture process on the transmission device 100b side is used in the depuncture process of step S204, and the bit LLR after the puncture process is used as a step. Used in S208.
In step S208, an interference replica from another antenna unit of MIMO is generated from the bit LLR and used in step S201.

In the transmission device 100b of the communication system according to the second exemplary embodiment of the present invention, the puncture units 2-1 to 2- _NT perform puncturing processing for thinning out signals to be transmitted to the reception device 200b, and the puncture units 2-1 to 2- The radio unit 5-1 to 5-N _T (also referred to as a transmission unit) transmits a signal subjected to the puncture processing by N _T to the reception device 200b.
The receiving device 200b of a communication system according to a second embodiment of the present invention, a soft decision value calculated demodulator 18-1 to _{18-N R} is by performing the demodulation processing, transmission of the signal by the transmission device 100b sometimes the position of the decimated signal by puncturing processing, performs a depuncturing process of inserting the soft decision value is depuncturing section 19 - 1 through _{19-N R,} depuncturing section 19 - 1 through _{19-N R} is subjected to the depuncturing and the error correction decoding process performed by the decoding unit 20-1 to _{20-N R} to the signal, out of the soft decision value decoding unit 20-1 to _{20-N R} is included in the signal subjected to error correction decoding processing receiving puncturing section 21 - 1 to _{21-N R} a soft decision value of decimated positions during puncturing of the transmitting apparatus 100b is determined.
Further, depuncturing section 19 - 1 through _{19-N R} of the reception device 200b according to the second embodiment of the present invention uses a soft-decision value received puncturing unit 21 - 1 to _{21-N R} is determined to de-puncturing.

  In the second embodiment of the present invention described above, the soft decision value is calculated on the receiving device 200b side by performing error correction decoding processing on the receiving device 200b side even for data not transmitted from the transmitting device 100b. By using the soft decision value again for the error correction decoding process, it is possible to improve the reception performance of the reception device 200b.

In the conventional technique, the transmitted bit likelihood is updated and the reception performance is gradually improved by repeated processing of interference cancellation and decoding processing, but only the likelihood of the depunctured bit is changed at 0. Absent.
However, when the bit likelihood subjected to the decoding process is used for depuncturing, the bit likelihood punctured on the transmitting apparatus 100b side is also updated, so that the error correction decoding performance is improved and the reception performance is further improved.

In the second embodiment, the case has been described in which depuncturing is performed in each iteration. However, the bit LLR obtained in the decoding process does not necessarily have to be depunctured, and any number of iterations may be performed. You may decide to depuncture. For example, depuncturing may be performed only at the last specified number of times in the iterative process.
In the second embodiment, a different data stream is transmitted for each antenna unit of the transmission device 100b. However, the present invention is not limited to this, and a plurality of data streams equal to or less than the number of antenna units of the transmission device 100b are transmitted to the reception device 200b. A plurality of data streams that are transmitted and transmitted on the receiving apparatus 200b side may be detected.

(Third embodiment)
Next, a communication system according to the third embodiment of the present invention will be described. This communication system includes a transmission device 100c and a reception device 200c. In the third embodiment, a case will be described in which the present invention is applied to MC-CDMA (Multi Carrier-code division multiple access).

FIG. 8 is a schematic block diagram showing a configuration of a transmission device 100c according to the third embodiment of the present invention. Transmission device 100c includes code channel signal generation unit _{29-1~29-C n} (C n is 2 or more integer), code multiplexing unit 30, IFFT unit 27, the parallel-to-serial converting unit 31, a pilot multiplexing unit 32 , A GI insertion unit 33, a radio unit 34, an antenna unit 6, and a pilot signal generation unit 35.

The code channel signal generation units 29-1 to 29 -C _n include a coding unit 1, a puncturing unit 2, a modulation unit 3, a serial / parallel conversion unit 28, and spreading units 29-1 to 29 -C _n . Transmitting apparatus 100c performs error correction coding on information bits in encoding section 1 of each code channel signal generation section 29-1 to 29-C _n and outputs encoded bits. Puncturing section 2 performs predetermined processing on the encoded bits. Performs puncturing processing to thin out bits.
The punctured encoded bits are mapped to modulation symbols by the modulation unit 3, are serial-parallel converted by the serial-parallel conversion unit 28, and are spread by the spreading codes corresponding to the spreading units 29-1 to 29 -C _n .

The code multiplexer 30 multiplexes the signals generated by the code channel signal generators. The code-multiplexed signal is frequency-time converted by the IFFT unit 27, parallel-serial converted by the parallel-serial converter 31, and the pilot signal generated by the pilot signal generator 35 is multiplexed by the pilot multiplexer 32.
Then, the guard interval is inserted by the GI insertion unit 33, the input signal is D / A converted by the radio unit 34, the waveform is shaped by a transmission filter (not shown), converted to radio frequency conversion, and received from the antenna unit 6. Is transmitted to the device 200c.

FIG. 9 is a schematic block diagram showing a configuration of a receiving device 200c according to the third embodiment of the present invention. The receiving device 200c includes an antenna unit 7, a radio unit 8, a GI removal unit 36, a serial-parallel conversion unit 28, an FFT unit 26, code channel signal detection units 40-1 to 40-C _n , a reception puncture unit 21, and a code channel replica. Generation units 44-1 to 44-C _n , an interference replica generation unit 45, and a propagation path estimation unit 46 are provided.

The code channel signal detecting unit 40-1 to _{40-C n,} subtraction unit 241, the propagation channel compensation unit 37, despreading section _{39-1~39-C n,} a parallel-serial converter 31, a demodulator 18, the depuncture A unit 19 and a decoding unit 20 are provided.
Code channel replica generation unit 44-1 to _{44-C n,} respectively, the symbol replica generation unit 41, serial-parallel converter 42, a spreading unit 43-1 to _{43-C n.}

A signal received by the antenna unit 7 is converted from a radio frequency to a baseband signal by the radio unit 8, shaped by a reception filter (not shown), A / D converted, a propagation path estimation unit 46 and an FFT unit. 26.
The propagation path estimation unit 46 performs propagation path estimation using the pilot signal, and the FFT unit 26 performs time frequency conversion. Code channel signal detecting unit 40-1 to _{40-C n} performs detection of the code channel signal from a signal after FFT.

Code channel signal detecting unit 40-1 to 40-C _n subtracts the first code interference replica generated by the interference replica generation unit 45, performs the interference cancellation. Signal after interference cancellation is propagation channel compensation in the channel compensator 37, despreading is performed using a corresponding spreading code despreader 39-1~39-C _n.
The despread signal is parallel-serial converted by the parallel-serial converter 31, and the demodulator 18 calculates the bit LLR by demodulation processing. Then, the depuncture unit 19 inserts the puncture bit LLR obtained from the reception puncture unit 21 at the position punctured on the transmission device 100c side.

Then, the decoding unit 20 performs error correction decoding processing. As a result of the decoding process, if there is no error in the information bits, or if the specified number of times of processing has been performed, the reception process ends. If there is an error in the information bits and the prescribed number of times of processing has not been performed, the decoding unit 20 outputs a coded bit LLR obtained by the decoding processing.
The encoded bit LLR output from the decoding unit 20 is input to the reception puncturing unit 21. The reception puncturing unit 21 performs puncturing processing on the encoded bits LLR in the same pattern as the puncturing unit 2 on the transmission device 100c side.

The bit LLR thinned out by the puncturing process is output to the depuncturing unit 21. Bit LLR punctured is output to the code channel replica generation unit 44-1 to _{44-C n.} Generating a replica of the modulation symbol from the bit LLR in the code channel replica generation unit 44-1 to _{44-C n} symbol replica generating unit 41 in.
Symbol replica are serial-to-parallel converted by serial-parallel converter 42, spread by the spreading code corresponding with a diffusion unit 43-1 to 43-C _n, it is input to the interference replica generator 45. The interference replica generation unit 45 generates a replica of inter-code interference.

In the transmission device 100c of the communication system according to the third embodiment of the present invention, the puncture unit 2 performs a puncturing process for thinning out a signal to be transmitted to the reception device 200c, and the signal obtained by the puncture unit 2 performs the puncture processing to the reception device 200c. Radio section 34 (also referred to as a transmission section) transmits.
Also, in the receiving device 200c of the communication system according to the third embodiment of the present invention, the demodulation unit 18 calculates a soft decision value by performing demodulation processing, and is thinned out by puncturing processing when a signal is transmitted by the transmitting device 100c. The depuncture unit 19 performs a depuncture process for inserting a soft decision value at the position of the received signal, and the decoding unit 20 performs an error correction decoding process on the signal that the depuncture unit 19 has performed the depuncture process. Of the soft decision values included in the signal subjected to the correction decoding process, the reception puncture unit 21 obtains a soft decision value at a position thinned out during the puncture processing in the transmission device 100c.
Further, the depuncture unit 19 of the reception device 200c according to the third embodiment of the present invention uses the soft decision value obtained by the reception puncture unit 19 for the depuncture process.

  In the above-described third embodiment of the present invention, the soft decision value is calculated on the receiving device 200c side by performing error correction decoding processing on the receiving device 200c side even for data not transmitted from the transmitting device 100c. By using the soft decision value again for the error correction decoding process, it is possible to improve the reception performance of the reception device 200c.

In the second or third embodiment described above, a case has been described in which interference from other antenna units and inter-code interference are considered as interference signals. However, the present invention is not limited to this, and is between symbols. You may make it consider other interferences, such as interference and interference between carriers.
In the second or third embodiment described above, among the bit LLRs obtained by the error correction decoding process, the thinned bit LLR is used for the depuncture process, and the thinned bit LLR is used for the interference replica generation. However, the present invention is not limited to this, the received signal is stored, the interference canceller is performed a specified number of times, and then the decoded bit LLR obtained at the end is thinned out by the reception puncture process. Only the bit LLR may be used to receive the stored received signal. When receiving the stored reception signal, interference cancellation is not performed for the first time of interference cancellation processing.

  In the embodiment described above, a program for realizing the function of each unit of the transmission device and each unit of the reception device according to the first to third embodiments of the present invention is recorded on a computer-readable recording medium, The program recorded on the recording medium may be read into a computer system and executed to control the transmitting device and the receiving device. Here, the “computer system” includes an OS and hardware such as peripheral devices.

  The “computer-readable recording medium” refers to a storage device such as a flexible medium, a magneto-optical disk, a portable medium such as a ROM and a CD-ROM, and a hard disk incorporated in a computer system. Further, the “computer-readable recording medium” dynamically holds a program for a short time, like a communication line when transmitting a program via a network such as the Internet or a communication line such as a telephone line. In this case, it is also assumed that a server that holds a program for a certain time, such as a volatile memory inside a computer system that serves as a server or client. The program may be a program for realizing a part of the functions described above, and may be a program capable of realizing the functions described above in combination with a program already recorded in a computer system.

  The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and the design and the like within the scope of the present invention are also within the scope of the claims. include.

It is a schematic block diagram which shows the structure of the transmitter 100a by the 1st Embodiment of this invention. It is a schematic block diagram which shows the structure of the receiver 200a by the 1st Embodiment of this invention. It is a flowchart which shows the process of the receiver 200a by the 1st Embodiment of this invention. It is a schematic block diagram which shows the structure of the transmitter 100b by the 2nd Embodiment of this invention. It is a schematic block diagram which shows the structure of the receiver 200b by the 2nd Embodiment of this invention. It is a schematic block diagram which shows the structure of the signal detection part 17 of the receiver 200b by the 2nd Embodiment of this invention. It is a flowchart which shows the process of the receiver 200b by the 2nd Embodiment of this invention. It is a schematic block diagram which shows the structure of the transmitter 100c by the 3rd Embodiment of this invention. It is a schematic block diagram which shows the structure of the receiver 200c by the 3rd Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Code | symbol part, 1-1 to 1-N _T ... Code part, 2 ... Puncture part, 2-1 to 2-N _T ... Puncture part, 3 ... Modulation part, 3 −1 to 3-N _T: Modulation unit, 4 ... Pilot multiplexing unit, 4-1 to 4-N _T ... Pilot multiplexing unit, 5 ... Radio unit, 5-1 to 5-N _T ... wireless section, 6 ... antenna unit, 6-1 to _6-N T ... antenna unit, 7 ... antenna unit, 7-1 to _7-N R ... antenna unit, 8・ ・ ・ Radio unit, 8-1 to 8-N _R・ ・ ・ Radio unit, 9 ... Propagation channel estimation unit, 10 ... Propagation channel compensation unit, 11 ... Demodulation unit, 12 ... Depuncture , 13 ... Decoding unit, 14 ... Reception puncture unit, 15 ... Storage unit, 16 ... Propagation path estimation unit, 17 ... Signal detection unit, 18-1 to 18-N _R · ..Demodulation section, 19-1 _9-N R ... depuncturing portion, 20-1 to _20-N R ... decoding unit, 21 ... receiving the puncturing unit, 21 - 1 to _21-N R ... receiving puncturing unit, 22-1 ˜22-N _R ... Symbol replica generation unit, 26... FFT unit, 26-1 to 26-N _R ... FFT unit, 27... IFFT unit, 28. 29-1 to _29-C n ... code channel signal generation unit, 30 ... code multiplexing unit, 31 ... parallel-serial conversion unit, 32 ... pilot multiplexing unit, 33 ... GI insertion unit, 33-1 to 33 -N _T ... GI insertion unit, 34 ... radio unit, 35 ... pilot signal generation unit, 36 ... GI removal unit, 36-1 to 36-N _R ... GI removing section, _40-1~40-C n ··· code channel signal detection unit, 44-1 to _{44-C n} ... code channel replica generation unit, 45 ... interference replica generation unit, 46 ... channel estimation unit, 100a-100c ... transmitting device, 200 a to 200 c ... receiving device

Claims (5)

A communication system comprising a transmission device and a reception device,
The transmitter is
A puncturing unit for performing a puncturing process for thinning out a signal to be transmitted to the receiving device;
A transmission unit that transmits a signal subjected to puncture processing by the puncture unit to the reception device;
The receiving device is:
A demodulation unit that calculates a soft decision value by performing demodulation processing;
A depuncturing unit for performing de-puncturing process with respect to the soft decision value in which the demodulator has been calculated,
A decoding unit that performs error correction decoding processing on the signal that has been subjected to depuncturing processing by the depuncturing unit;
A reception puncture unit for obtaining a soft decision value at a position thinned out during puncture processing in the transmission device among soft decision values included in a signal subjected to error correction decoding processing by the decoding unit;
The communication system, wherein the depuncture unit performs a depuncture process to insert the soft decision value obtained by the reception puncture unit into a position of a signal thinned out by a puncture process when a signal is transmitted by the transmission device . A receiving device that communicates with a transmitting device,
A demodulation unit that calculates a soft decision value by performing demodulation processing;
A depuncturing unit for performing de-puncturing process with respect to the soft decision value in which the demodulator has been calculated,
A decoding unit that performs error correction decoding processing on the signal that has been subjected to depuncturing processing by the depuncturing unit;
A reception puncture unit for obtaining a soft decision value at a position thinned out during puncture processing in the transmission device among soft decision values included in a signal subjected to error correction decoding processing by the decoding unit;
The receiving apparatus according to claim 1 , wherein the depuncturing section performs a depuncturing process for inserting the soft decision value obtained by the receiving puncturing section into a position of a signal thinned out by a puncturing process when a signal is transmitted by the transmitting apparatus. Further comprising an interference replica generation unit, a subtraction unit, a signal detection unit, a propagation path estimation unit,
The reception puncture unit obtains a soft decision value at a position where the signal is thinned by the transmission device and a soft decision value subjected to puncture processing,
The interference replica generation unit generates a replica of an interference signal based on the soft decision value punctured by the reception puncture unit,
The subtracting unit performs interference removal by subtracting a replica of the interference signal from the received signal,
The signal detection unit performs signal detection on the signal after the interference removal,
The receiving apparatus according to claim 2, wherein the demodulation unit demodulates the signal detected by the signal detection unit. The receiving apparatus according to claim 2, wherein the depuncturing unit performs a depuncturing process on the soft decision value obtained by the reception puncturing unit only in the last iteration. A communication method using a receiver that communicates with a transmitter,
A demodulation process for calculating a soft decision value by performing a demodulation process;
A depuncturing process of performing de-puncturing process with respect to the soft decision value in which the demodulator has been calculated,
A decoding process for performing error correction decoding processing on the signal that has been depunctured in the depuncturing process;
A reception puncturing process for obtaining a soft decision value at a position thinned out during puncturing processing in the transmitting device among soft decision values included in a signal subjected to error correction decoding processing in the decoding process;
Wherein the de-puncturing process, communication method and performing de-puncturing process of inserting a soft decision value which has been determined by the received puncturing process, the position of the transmitting device signal the signal punctured by puncturing process when sending by.

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