WO2019159430A1

WO2019159430A1 - Wireless communication method and wireless communication system

Info

Publication number: WO2019159430A1
Application number: PCT/JP2018/038055
Authority: WO
Inventors: 敬亮山本
Original assignee: 株式会社日立国際電気
Priority date: 2018-02-19
Filing date: 2018-10-12
Publication date: 2019-08-22
Also published as: JP6872073B2; JPWO2019159430A1

Abstract

In this wireless communication system which transmits data from a transmission device to a receiving device, the transmission device has a modulator which outputs DPSK signals in parallel by using OFDM, and the receiving device is composed of: an MLSE demodulator which demodulates a wireless signal and outputs bit information; a decoder which decodes the bit information; an interleave processing unit which exchanges a bit sequence of the bit information; a deinterleaver for differential phase-shift keying; and a deinterleave processing unit which is composed of a deinterleaver for repetitive decoding having a block length smaller than that of the deinterleaver for differential phase-shift keying, and exchanges the bit sequence of the bit information, wherein the deinterleaver for differential phase-shift keying has a function of performing a deinterleave process by exchanging a time sequence of the DPSK signals transmitted in parallel.

Description

Wireless communication method and wireless communication system

Import by reference

This application claims the priority of Japanese Patent Application No. 2018-27242, which was filed on February 19, 2018, and is incorporated herein by reference.

The present invention relates to a wireless communication method for transmitting and receiving data via a wireless propagation path.

As a background technology in this technical field, a technique called BICM-ID (Bit Interleaved Coded Modulation with Iterative decoding) has been proposed. For example, as described in Patent Document 1 and Non-Patent Document 2, in BICM-ID, excellent characteristics can be obtained by repeating demodulation processing for modulation and decoding processing for encoding. The characteristics of the BICM-ID are determined not by the characteristics of the demodulator and the decoder but by their matching. For this reason, it is possible to analyze a convergence characteristic using EXT (Extrinsic Information Transfer) analysis and design a demodulator and a decoder that realize excellent characteristics (see, for example, Non-Patent Document 3).

Further, in a receiving apparatus using a combination of orthogonal frequency division multiplexing (OFDM) and differential phase shift (DPSK) modulation, a soft decision result of a maximum likelihood sequence estimation (MLSE) of a DPSK modulated signal and a decoder are used. A method has been proposed in which performance is improved by performing BICM-ID as compared with normal delay detection without using BICM-ID.

JP 2010-124367 A

In a conventional system in which DPSK signals are transmitted in parallel by OFDM, a scheme has been proposed that realizes good characteristics by applying iterative decoding processing using the MLSE and BICM-ID schemes for demodulation processing. However, in the iterative decoding method using MLSE and BICM-ID, the symbol length of the DPSK signal for realizing good convergence characteristics with BICM-ID becomes large. An increase in the circuit scale of the decoding processing unit becomes a problem. In particular, the circuit scales of the interleaver and deinterleaver that randomly change the order of signals are determined by the size of data to be processed, which can be a bottleneck for circuit scale reduction.

A typical example of the invention disclosed in the present application is as follows. That is, a wireless communication method for transmitting data from a transmission apparatus to a reception apparatus, wherein the transmission apparatus includes a modulator that outputs a DPSK signal in parallel using OFDM, and the reception apparatus demodulates the radio signal. An MLSE demodulator that outputs bit information, a decoder that decodes the bit information, an interleave processing unit that changes the bit order of the bit information, a deinterleaver for differential phase shift, and the differential phase shift A deinterleaver for repetitive decoding having a block length smaller than that of the transfer deinterleaver, and having a deinterleave processing unit for changing the bit order of the bit information, and the differential phase shift deinterleaver transmits in parallel Having a function of performing a deinterleaving process by changing the time order of the DPSK signals generated, and the method includes: The deinterleaver for transfer and the MLSE demodulator perform deinterleave processing and demodulation processing on the first radio signal output from the OFDM demodulator, output first bit information, and the deinterleaver for iterative decoding, The first bit information is deinterleaved to return the order of the bits exchanged in the interleaving process, and the second bit information is output. The decoder decodes the second bit information. Then, the third bit information is output, and the interleave processing unit performs an interleaving process that is the reverse of the deinterleaving process on the third bit information to generate fourth bit information, By inputting the fourth bit information as prior information to the MLSE demodulator, iterative decoding processing is performed.

According to the representative embodiment of the present invention, it is possible to suppress an increase in the circuit scale of the iterative decoding process while improving the characteristics of the iterative decoding process. Problems, configurations, and effects other than those described above will become apparent from the following description of embodiments.

It is a figure which shows the structure of the radio | wireless communications system of the Example of this invention. It is a figure which shows the iterative decoding process in the retransmission method of the Example of this invention, FIG. 2 (A) is a figure which shows the iterative decoding process part of the receiving side in a present Example, FIG.2 (B) is an EXIT analysis result FIG. FIG. 3A is a diagram illustrating an iterative decoding process according to an embodiment of the present invention, and FIG. 3A is a diagram illustrating a configuration in which an interleaver and a deinterleaver are divided for differential phase shift and iterative decoding processing. FIG. 7B is a diagram illustrating a configuration in which a differential phase shift deinterleaver is provided outside the iterative decoding processing unit. It is a figure which shows the iterative decoding process using OFDM and DPSK of the Example of this invention. It is a figure which shows the iterative decoding process using OFDM and DPSK of the Example of this invention. It is a figure which shows an example of the deinterleaving process for DPSK. It is a figure which shows an example of the deinterleaving process for DPSK of the Example of this invention. It is a figure which shows an example of the deinterleaving process for iterative decoding processes. It is a figure which shows an example of the deinterleaving process for iterative decoding processes of the Example of this invention. It is a figure which shows the structure of the deinterleaver for iterative decoding of the Example of this invention. It is a figure which shows an example of the deinterleaving process for iterative decoding processes of the Example of this invention. It is a figure which shows the error rate characteristic in the radio | wireless communications system of the Example of this invention.

<Example 1>
Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram showing a configuration of a wireless communication system according to an embodiment of the present invention.

The wireless communication system of the present embodiment includes an encoder 10, an interleaver 11, a DPSK (differential phase shift) modulator 12, a transmitter having an OFDM (orthogonal frequency division multiplexing) modulator 13, and an antenna 14, and an OFDM demodulator. 17, a receiver having an iterative decoding processing unit 21 and an antenna 16. A transmitter and a receiver are connected via a wireless propagation path 15.

In the transmitter, the encoder 10 encodes information bits, the interleaver 11 switches the bit order in the code word output from the encoder 10, the DPSK modulator 12 performs differential shift keying, and the OFDM modulator 13 Output a plurality of DPSK signals from the antenna 14 on the subcarriers.

The iterative decoding processing unit 21 of the receiver includes a DPSK demodulator 18, a deinterleaver 19, a decoder 20, and an interleaver 24. In the receiver, a signal is received via the radio propagation path 15, the OFDM demodulator 17 demodulates the received signal, a DPSK demodulator 18 demodulates the demodulation result, and a deinterleaver 19 that performs reverse processing of the interleaver 11. The bit order is restored and the decoder 20 performs decoding. The decoding result is input to the DPSK demodulator 18 via the interleaver 24, and the DPSK demodulator 18 refers to the decoding result of the decoder 20 and outputs a more accurate demodulation result (BICM-ID processing).

FIG. 2A is a diagram illustrating the iterative decoding processing unit 21 of the receiver in this embodiment, and FIG. 2B is a diagram illustrating the EXIT analysis result of the iterative decoding processing. In the DPSK soft decision decoding process, blind (no channel information) demodulation using maximum likelihood sequence estimation (MLSE) is used.

As the likelihood information exchanged between the demodulator and the decoder using BICM-ID, a log-likelihood ratio (LLR: Log Likelihood Ratio) in units of bits is generally used. LLR is a logarithmic expression of the ratio between the probability that the bit b is 0 and the probability that it is 1, and is expressed by Equation (1).

In Equation (1), P (b = 0) indicates the probability that b is 0, and P (b = 1) indicates the probability that b is 1.

The convergence characteristics of the BICM-ID iterative decoding process can be analyzed by EXT (Extrinsic Information Transfer) analysis described in Non-Patent Document 3. In the EXIT analysis, the input / output characteristics of the decoder and demodulator are displayed in the form of the mutual information amount Im of the bit expressed by Equation (2), and the characteristics of both are overlapped and plotted on one chart for repeated decoding. The amount of information obtained by processing can be analyzed.

The mutual information amount in Equation (2) is an average of the entire code word of the mutual information amount of bits, and is expressed by a value of 0 to 1, and the closer to 1, the greater the bit likelihood of the entire code word.

Prior information _{I A demodulator, DEM} and the decoder of the external information _{I E,} the _DEC on the horizontal axis, the external information _{I A demodulator, DEM,} prior information _{I E} of the _decoder, taking the vertical axis to _DEC, The mutual information amount increases along each characteristic by the iterative decoding process. When the characteristics of the two intersect, the increase of the mutual information stops at the intersection, and an error remains in the decoding result. In FIG. 2B, since the convergence characteristics of the demodulator and the decoder do not intersect with the analysis result 23, it is possible to obtain an error-free result. However, since the convergence characteristic is determined by the average of the entire codeword, a codeword that is sufficiently asymptotic to the average value is required. In DPSK modulation using OFDM, DPSK modulation is used in the time direction in order to follow the time variation of the channel. In this case, the DPSK modulation data of each subcarrier is one per OFDM symbol, and good convergence is achieved. In general, 1000 OFDM symbols or more are required to obtain DPSK modulation data for obtaining characteristics. In this case, the scale of data processed by the iterative decoding processing unit increases, and in particular, the scale of the interleaver and deinterleaver can become a bottleneck in reducing the circuit scale.

In the present invention, in order to solve the problem of circuit scale, DPSK signals transmitted in parallel are associated through the interleaver 24, the decoder 20 and the deinterleaver 19, thereby bundling fewer OFDM symbols DPSK signals in the subcarrier direction. In addition, a signal processing method for forming a codeword capable of obtaining good convergence characteristics and a method for dividing the interleaver 24 and the deinterleaver 19 into a plurality of parts and reducing the interleaver 24 and the deinterleaver 19 included in the iterative decoding unit are provided.

FIG. 3 is a diagram showing the iterative decoding processing unit 21 of the embodiment of the present invention. FIG. 3A divides the deinterleaver into a differential phase shift deinterleaver 31 and an iterative decoding deinterleaver 32. FIG. 3B is a diagram illustrating a configuration in which the interleaver is divided into a differential phase shift 33 and an iterative decoding process 32. FIG. 3B illustrates the differential phase shift deinterleaver 31 that repeatedly performs the decoding process. It is a figure which shows the structure provided in the exterior.

In the embodiment of the present invention, since DPSK signals of a plurality of subcarriers are bundled and handled as one code word, the minimum required OFDM symbol length can be shortened to obtain good characteristics with BICM-ID. However, since the original size of the interleaver is selected so as to be sufficiently large to obtain diversity with respect to channel fluctuation, it is not determined only by the codeword size necessary for the convergence characteristics of BICM-ID. Therefore, the differential phase shift deinterleaver 31 whose magnitude is selected with respect to the channel fluctuation and the deinterleaver 32 required by the iterative decoding processing unit 21 are divided into the differential phase shift deinterleaver, and the differential phase shift deinterleave processing is the iterative decoding. It is set as the structure performed before. In FIG. 3A, the differential phase shift deinterleaver 31 has a larger block size than the iterative decoding deinterleaver 32, and is designed to obtain sufficient diversity with respect to channel variations.

Here, the MLSE demodulator 22 executes a process of estimating a transmission bit from the phase difference between adjacent signals, and if the differential phase shift deinterleaver 31 maintains the context of the DPSK signal, MLSE and The order of the above can be exchanged and taken out of the iterative decoding processing unit 21. That is, as shown in FIG. 3B, the differential phase shift deinterleaver 31 is provided in the preceding stage of the MLSE demodulator 22 and executes processing outside the iterative decoding processing unit 21. Phase shift deinterleaving is not required. With this configuration, the circuit scale of the iterative decoding processing unit 21 can be reduced. The deinterleaving process is an inverse process of the interleaving process. Hereinafter, the interleaving process and the deinterleaving process according to the embodiment of the present invention will be described mainly using the deinterleaving process on the receiving side.

FIG. 4 is a diagram illustrating an iterative decoding process using OFDM and DPSK. The DPSK signal 41 is arranged in the OFDM time direction, and the DSPK signals in the frequency direction are independent of each other. In MLSE, processing of DPSK symbols 42 requires adjacent DPSK signals, so interleaving and deinterleaving between MLSE 22 and decoder 20 when the order of DPSK signals in the time direction is interleaved. Is required. The iterative decoding processing unit 21 repeatedly decodes a sufficiently long DPSK signal and the decoding result of the decoder 20 for each subcarrier.

FIG. 5 is a diagram showing an iterative decoding process using OFDM and DPSK according to an embodiment of the present invention. The DPSK signal is shorter than the symbol length of the differential phase shift deinterleaver 31, and a plurality of subcarrier DPSK signals are processed as one MLSE group. Decoding results are also collected in time and subcarrier directions as one codeword, and iterative decoding is performed.

Next, the differential phase shift interleaving process and the deinterleaving process according to the embodiment of the present invention will be described with reference to FIGS.

FIG. 6 is a diagram illustrating an example of a conventional differential phase shift deinterleaving process, and the time of DPSK symbols 42 in the DPSK signal 41 of the subcarrier before and after the deinterleaving process in which the time order of 100 OFDM symbols is switched at random. Indicates the order. In FIG. 6, the deinterleaving result 61 is that the time order of the DPSK symbols 42 is changed in the subcarriers before the deinterleaving. Therefore, it is necessary to restore the order changed before the MLSE. It is difficult to put 31 out of iterative decoding.

FIG. 7 is a diagram showing an example of the deinterleaving process for differential phase shift according to the embodiment of the present invention. In FIG. 7, the deinterleaving result 71 realizes the deinterleaving function by changing the time order between the subcarriers while maintaining the time order of the DPSK symbols 42 in the DPSK signal 41 of the subcarrier. In the DPSK symbol 42 after deinterleaving, a delay of 1 to 100 symbols is randomly inserted for each subcarrier. If the number of subcarriers is sufficiently large, a diversity effect of 100 symbols can be expected. In this case, in the DPSK signal 41, the time order of the DPSK symbols 42 is maintained before and after deinterleaving, and the relationship between adjacent DPSK symbols 42 necessary for MLSE is maintained. Therefore, the order of MLSE and interleaving is changed. Can be easily replaced.

Next, iterative decoding interleaving and deinterleaving processing according to an embodiment of the present invention will be described with reference to FIGS.

FIG. 8 is a diagram showing an example of deinterleaving processing using a conventional interleaver as a deinterleaver for iterative decoding processing. In deinterleaving for iterative processing, a signal that has been deinterleaved in the time direction by deinterleaving for differential phase shift is deinterleaved. It is desirable that the deinterleaving process of the iterative decoding unit be as small as possible. However, when deinterleaving in the frequency direction in units of OFDM symbols is simply combined, the likelihood of the DPSK signal 41 of each subcarrier in the iterative decoding process Information is not exchanged and good convergence characteristics cannot be realized. Whether or not the DPSK signal 41 is associated in the iterative decoding process can be confirmed by an index in the subcarrier direction 81 after deinterleaving. In the deinterleave result 81 shown in FIG. 8, the index in the subcarrier direction of the DPSK signal 41 only includes f75, and the association between the DPSK signals 41 is limited.

FIG. 9 is a diagram illustrating an example of deinterleaving processing for iterative decoding processing according to the embodiment of this invention. The deinterleaver shown in FIG. 9 randomly swaps both the time and frequency directions in the MLSE group of the demodulator. In the DPSK signal 41 of the deinterleave result 91 shown in FIG. 9, the index in the frequency direction includes f75, f99, f72, and f42, and likelihood information is exchanged between the DPSK signals of these subcarriers. In this case, interleaving processing and deinterleaving processing are required before and after MLSE, but the symbol size is shorter than that of the differential phase shift deinterleaver, so that the circuit scale can be reduced.

Although good characteristics can be obtained by using the block interleaver shown in FIG. 9, the function required as the iterative decoding interleaver according to the embodiment of the present invention is that the interleaving process is different from one OFDM symbol unit. That is, as shown in FIG. 8, if the unit of interleaving processing is equal to one OFDM symbol unit, the interleaving processing is performed in OFDM symbol units. However, as shown in FIG. 9, the unit of interleaving processing is one OFDM symbol. If it is different from the unit, the shift width is changed for each interleave process, and the interleave process is shifted from the OFDM symbol unit. That is, the likelihood information of a plurality of subcarriers is included in the DPSK signal 41 of one subcarrier after the interleaving processing and the deinterleaving processing of all DPSK signals in the MLSE group are completed. For this reason, better characteristics can be realized. The unit of interleaving processing is preferably larger than one OFDM symbol unit, but may be smaller.

Also, even if the interleaving process is the same as one OFDM symbol unit, good characteristics can be realized by combining convolutional bit interleaving and a plurality of interleaving.

FIG. 10 shows the configuration of the deinterleaver 32 for iterative decoding when the interleaving process is the same as for one OFDM and combined with a convolutional bit interleaver. The block deinterleaver 102 is, for example, a deinterleaver that restores the original order in which subcarrier positions in one OFDM symbol are randomly interleaved (bits on subcarriers in units of subcarriers). The output of the deinterleaver is delayed by the bitwise convolutional deinterleaver 101, and the delay added by the interleaving is returned to the original order. In this case, although the deinterleaving process by the block deinterleaver 102 is closed in one OFDM symbol, some bits in one OFDM symbol are mixed with bits in other OFDM symbols in the subsequent convolutional deinterleaver. In the iterative decoding of the present invention, good characteristics can be realized.

The iterative decoding deinterleaver 32 shown in FIG. 10 can change the bit order with different replacement patterns when viewed in bit units. That is, the interleave pattern can be switched for each OFDM symbol, and likelihood information is exchanged between the DPSK signals of the subcarriers, so that good characteristics can be realized.

FIG. 11 is a diagram illustrating an example in which a plurality of OFDM symbol deinterleavers are combined. In FIG. 11, the deinterleaver randomly replaces subcarriers in one OFDM symbol. However, a different interleaving pattern is used for each OFDM symbol, and the DPSK signal 41 of the deinterleaving result 111 includes frequency indexes f75, f99, f72, and f42, and likelihood information between the DPSK signals of these subcarriers. Will be replaced. In the example shown in FIG. 11, good characteristics can be realized without combining with the convolutional deinterleaver 101 as shown in FIG.

FIG. 12 is a diagram showing error rate characteristics in the wireless communication system according to the embodiment of the present invention. The characteristic of delay detection when BICM-ID is not used is represented by □, the characteristic when BICM-ID is used is represented by ◯, and the characteristic using the iterative decoding unit of the embodiment of the present invention is represented by ×. From FIG. 12, by using the technique of the present invention, it is possible to improve the SNR over the BICM-ID while reducing the circuit scale.

As described above, according to the embodiment of the present invention, a radio communication system that transmits data from a transmission device to a reception device, the differential phase shift deinterleaver 31 and the MLSE demodulator 22 cooperate. The first radio signal output from the OFDM demodulator 17 is deinterleaved and demodulated to output first bit information. The iterative decoding deinterleaver 32 applies the first bit information to the first bit information. Deinterleaving is performed to restore the order of the bits replaced in the interleaving process, and the second bit information is output. The decoder 20 decodes the second bit information and outputs the third bit information. Then, the interleaving processing unit 34 performs interleaving processing that is the reverse of the deinterleaving processing on the third bit information to generate fourth bit information, and the second bit information. Is input to the MLSE demodulator as prior information, so that the iterative decoding process is performed, and the characteristics of the iterative decoding process are improved (required SNR in the error rate characteristic is reduced), while suppressing the increase in the circuit scale of the iterative decoding process it can.

Further, the differential phase shift deinterleaver 31 is arranged in front of the MLSE demodulator 22, and the differential phase shift deinterleaver 31 performs the second radio signal obtained by deinterleaving the first radio signal. The signal is output, and the MLSE demodulator 22 demodulates the second radio signal using the prior information and outputs the first bit information, so that the differential phase shift deinterleaver 31 is repeatedly decoded. , The differential phase shift deinterleaving process is unnecessary, and the circuit scale of the iterative decoding processing unit 21 can be reduced.

The iterative decoding deinterleaver 32 has a function of changing the bit order across at least two OFDM signals, and the MLSE demodulator 22 has a smaller block size than the differential phase shift deinterleaver 31. Since the demodulated result of the DPSK signal demodulated by modulating the demodulated signal and the bit order being changed by the iterative decoding deinterleaver 32 is repeatedly decoded between the decoders 20, the interleaving process deviates from the OFDM symbol unit. Likelihood information is exchanged between the DPSK signals of the carriers, and better characteristics can be realized.

Further, since the deinterleaver 32 for iterative decoding has a function of changing the bit order across at least two OFDM signals, the size of the bit information to be exchanged is different from that of one OFDM symbol, interleave processing is performed in units of OFDM symbols. Therefore, likelihood information is exchanged between DPSK signals of subcarriers, and better characteristics can be realized.

In addition, the iterative decoding deinterleaver 32 has the function of changing the bit order with different replacement patterns across at least two or more OFDM signals in which the size of the bit information to be replaced is the same as that of one OFDM symbol. Since the symbol unit and the interleave processing are shifted, likelihood information is exchanged between the subcarrier DPSK signals, and better characteristics can be realized.

The iterative decoding deinterleaver 32 is composed of a deinterleaver having the same bit information size as one OFDM symbol and an interleaver having a different delay time in one OFDM symbol. Interleaving patterns can be switched, likelihood information is exchanged between subcarrier DPSK signals, and good characteristics can be realized.

The present invention is not limited to the above-described embodiments, and includes various modifications and equivalent configurations within the scope of the appended claims. For example, the above-described embodiments have been described in detail for easy understanding of the present invention, and the present invention is not necessarily limited to those having all the configurations described. A part of the configuration of one embodiment may be replaced with the configuration of another embodiment. Moreover, you may add the structure of another Example to the structure of a certain Example. In addition, for a part of the configuration of each embodiment, another configuration may be added, deleted, or replaced.

In addition, each of the above-described configurations, functions, processing units, processing means, etc. may be realized in hardware by designing a part or all of them, for example, with an integrated circuit, and the processor realizes each function. It may be realized by software by interpreting and executing the program to be executed.

Information such as programs, tables, and files that realize each function can be stored in a storage device such as a memory, a hard disk, and an SSD (Solid State Drive), or a recording medium such as an IC card, an SD card, and a DVD.

Also, the control lines and information lines indicate what is considered necessary for the explanation, and do not necessarily indicate all control lines and information lines necessary for mounting. In practice, it can be considered that almost all the components are connected to each other.

Claims

A wireless communication method for transmitting data from a transmitting device to a receiving device,
The transmitter has a modulator that outputs a DPSK signal in parallel using OFDM,
The receiving device is:
An MLSE demodulator that demodulates a radio signal and outputs bit information;
A decoder for decoding the bit information;
An interleaving processing unit for performing an interleaving process for switching the bit order of the bit information;
A deinterleave process comprising a differential phase shift deinterleaver and an iterative decoding deinterleaver having a block length smaller than that of the differential phase shift deinterleaver, and performing a deinterleave process for changing the bit order of the bit information And
The method
The differential phase shift deinterleaver and the MLSE demodulator perform deinterleave processing and demodulation processing on the first radio signal output from the OFDM demodulator, and output first bit information;
The iterative decoding deinterleaver performs deinterleaving processing for returning the order of the bits exchanged in the interleaving processing to the first bit information, and outputs second bit information;
The decoder decodes the second bit information and outputs third bit information;
The interleave processing unit performs interleaving processing on the third bit information, which is the reverse of the deinterleaving processing, to generate fourth bit information. The MLSE demodulation is performed using the fourth bit information as prior information. Input
A wireless communication method characterized by repeatedly performing decoding processing by the above processing.
The wireless communication method according to claim 1,
The differential phase shift deinterleaver is disposed in front of the MLSE demodulator,
The method
The differential phase shift deinterleaver outputs a second radio signal obtained by deinterleaving the first radio signal;
The wireless communication method, wherein the MLSE demodulator demodulates a second wireless signal using the prior information and outputs first bit information.
The wireless communication method according to claim 1,
The wireless communication method, wherein the iterative decoding deinterleaver changes the bit order across at least two OFDM signals.
The wireless communication method according to claim 1,
The iterative decoding deinterleaver is characterized in that the bit information to be exchanged is different from one OFDM symbol and the bit order is exchanged across at least two OFDM signals.
The wireless communication method according to claim 1,
The iterative decoding deinterleaver, wherein the bit information to be exchanged has the same size as one OFDM symbol, and exchanges the bit order with different exchange patterns across at least two OFDM signals. .
The wireless communication method according to claim 5,
The iterative decoding deinterleaver comprises a deinterleaver having the same bit information size to be replaced with one OFDM symbol, and an interleaver having a different delay time within one OFDM symbol. .
A wireless communication system for transmitting data from a transmitting device to a receiving device,
The transmitter has a modulator that outputs a DPSK signal in parallel using OFDM,
The receiving device is:
An MLSE demodulator that demodulates a radio signal and outputs bit information;
A decoder for decoding the bit information;
An interleaving processing unit for performing an interleaving process for switching the bit order of the bit information;
A deinterleave process comprising a differential phase shift deinterleaver and an iterative decoding deinterleaver having a block length smaller than that of the differential phase shift deinterleaver, and performing a deinterleave process for changing the bit order of the bit information And
The differential phase shift deinterleaver and the MLSE demodulator perform deinterleave processing and demodulation processing on the first radio signal output from the OFDM demodulator, and output first bit information,
The iterative decoding deinterleaver performs deinterleaving processing for returning the order of the bits exchanged in the interleaving processing to the first bit information, and outputs second bit information,
The decoder decodes the second bit information and outputs third bit information;
The interleaving unit performs interleaving on the third bit information, which is the reverse of the deinterleaving process, to generate fourth bit information, and uses the fourth bit information as prior information to perform the MLSE demodulation. Input
A wireless communication system that performs iterative decoding processing by the above processing.
The wireless communication system according to claim 7,
The differential phase shift deinterleaver is disposed in front of the MLSE demodulator,
The differential phase shift deinterleaver outputs a second radio signal obtained by deinterleaving the first radio signal;
The MLSE demodulator demodulates a second radio signal using the prior information and outputs first bit information.
The wireless communication system according to claim 7,
The iterative decoding deinterleaver has a function of changing a bit order across at least two OFDM signals.
The wireless communication system according to claim 7,
The iterative decoding deinterleaver is a wireless communication system having a function of changing bit order across at least two or more OFDM signals, the size of bit information to be changed being different from one OFDM symbol.
The wireless communication system according to claim 7,
The iterative decoding deinterleaver is characterized in that the size of bit information to be exchanged is the same as that of one OFDM symbol, and has a function of exchanging bit order with different exchange patterns across at least two or more OFDM signals. Wireless communication system.
A wireless communication system according to claim 11, wherein
The iterative decoding deinterleaver is composed of a deinterleaver having the same bit information size as that of one OFDM symbol and an interleaver having a different delay time in one OFDM symbol. .