CN105024706A - BCH+RS-based cascade error correction coding method and system - Google Patents

Abstract

The present invention provides an error correction coding method and system based on BCH+RS cascading. The method of the present invention is an enhanced error correction coding method. The data is first encoded by RS and then encoded by BCH. By cascading these two encoding methods, the error correction capability of the error correction coding at the data sending end is strengthened, and BCH decoding, RS decoding and RS erasure decoding are performed successively at the receiving end. Using error correction decoding to reduce the bit error rate of data signals, using this method of BCH code interleaving and RS erasure decoding can further improve the ability to resist burst errors, and the effect of error correction has been greatly improved.

Description

A BCH+RS cascaded error correction coding method and system based on

technical field

The present invention relates to the field of communication data error correction, and more specifically, relates to a BCH+RS cascaded error correction coding method and system.

Background technique

In the digital communication system, when the digital signal is transmitted on the actual channel, due to the unsatisfactory channel transmission characteristics and the interference of additive noise, the received digital signal will inevitably have errors. Channel error-correcting codes are a coding and decoding method designed to improve transmission quality and ensure reliability of information transmission. Its basic method is to add some check bits to the transmitted information sequence at the sending end, and these redundant check bits and information bits are related to each other through certain rules. The receiving end checks the relationship between the information bit and the check bit according to the established rules. Once an error occurs during the transmission process, the constraint relationship between the information bit and the check bit is destroyed, so that errors can be found and even corrected.

Since the signal will inevitably be interfered by external noise during the transmission process, the unsatisfactory channel will also cause signal distortion, resulting in an error in the received signal. Adopting an appropriate error correction coding method can effectively correct errors occurring in the transmission process and improve the success rate of packet data transmission.

According to the channel error control theory, for any positive integer m (m≥3) and t (t<2 ^m-1 ), there is a binary BCH code with the following parameters:

Code length: n=2 ^m -1;

Supervisory digits: n-k=mt, k is the information bit length;

Minimum distance: d _min =2t+1.

The code can correct any combination of t or less than t errors in a code group with length n, which is generally expressed as a BCH (n, k, t) code.

Reed-Solomon (Reed-Solomon, RS) code abbreviation (RS code) is the most important subclass in the q-ary BCH code. An RS code whose symbols are taken from GF(q) and corrects t errors has the following parameters:

Code length: n=q-1;

The number of supervisory symbols: n-k=2t, k is the information bit length;

Number of information symbols: k=q-1-2t

Minimum distance: d _min =2t+1.

Often expressed as RS (n, k, t) code. RS is a multi-ary maximum and minimum distance BCH code, and its error correction ability and coding efficiency are the highest among linear block codes. In engineering application, considering the convenience of computer processing, generally q is taken as 2 ^m . At this time, a character can be simply considered to be composed of m bits, so the error of continuous m bits is only equivalent to the error of one symbol of the code, so the RS code is The ability to resist burst errors can be greatly improved.

In actual use, RS (n, k, t) decoding can adopt erasure decoding. An RS code that corrects t errors can be used to correct all combinations of v symbol errors and e symbol deletions as long as the inequality

$\mathrm{<span\; class="notranslate">\; v</span>}<span\; class="notranslate">\; +</span>\frac{\mathrm{<span\; class="notranslate">\; e</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; \&le;</span>\mathrm{<span\; class="notranslate">\; t</span>}$

established. Its significance lies in that during RS decoding, if the location of some errors is known, the error correction capability can be improved. For example RS (200,100,50) code, if know all 100 error positions, namely v=0, e=100, satisfy At this time, the RS (200, 100, 50) decoder can correct all errors, and the error correction ability is doubled compared with the situation where no error location is known (only 50 error characters can be corrected).

The existing ARQ method is often used to improve the success rate of packet data transmission, that is, an error correction + retransmission method is adopted. When the transmission fails, the sender performs retransmission. For ARQ, under the condition of high bit error narrowband wireless channel, if the error correction coding capability adopted is insufficient, the probability of retransmission failure is also high. Multiple retransmissions will also bring problems such as increased transmission delay and low channel utilization rate, which often fail to achieve good results, let alone be applicable to real-time services such as packet voice.

Contents of the invention

The invention provides an error correction coding method based on BCH+RS cascading to realize reducing the bit error rate of data signals in high bit error narrowband wireless channel packet data communication.

Another object of the present invention is to provide a BCH+RS concatenated error correction coding system.

In order to achieve the above-mentioned technical effect, the technical scheme of the present invention is as follows:

A method for cascading error correction coding based on BCH+RS, comprising the steps of:

S1: Divide the L data to be sent into r columns at the data sending end of the channel, and the data length of each column is m, then L=m×r;

S2: Assuming that the codeword length of the RS code is n, the maximum error correction capability of the RS code is t, and performing RS (n, m, t) encoding on each column of data in the r column data;

S3: Perform BCH (n ₀ , m ₀ , t ₀ ) encoding on the r number data of each row after RS (n, m, t) encoding, and the data sending end sends the encoded data to the channel in the channel The data receiving end sends sequentially, where n ₀ is the data length, m ₀ is the information bit length, and t ₀ is the maximum error correction capability;

S4: Perform BCH (n0, m0, t0) decoding on each column of data received at the data receiving end of the channel. When the decoding is successful, the correct information will be restored. When the decoding fails, the position of the error code word will be recorded. information;

S5: At the data receiving end of the channel, each column of data decoded by BCH (n0, m0, t0) is decoded by RS (n, m, t), and the error position information obtained in S4 is used to delete and decode Encoding method to obtain error-corrected data.

A cascaded error correction coding system based on BCH+RS, including a data sending end and a data receiving end located at both ends of the channel; the data sending end includes a sequentially connected RS encoder and a BCH encoder, and the data receiving end includes a sequentially connected BCH Decoder and RS decoder; the BCH encoder at the data sending end is connected to the BCH decoder at the data receiving end; the data passes through the RS encoder, BCH encoder, BCH decoder and RS decoder in sequence to complete the error correction process .

Compared with the prior art, the beneficial effects of the technical solution of the present invention are:

The present invention is an enhanced error correction coding method. Aiming at high-error narrowband wireless channel packet data communication, the data to be sent is firstly RS coded and then BCH coded at the sending end, and the two coding methods are cascaded to achieve Strengthen the error correction capability of the error correction coding at the data sending end, and perform BCH decoding, RS decoding, and RS erasure decoding at the receiving end successively to reduce the bit error rate of the data signal. Using this BCH code interleaving, RS The method of erasure decoding can further improve the ability of resisting burst errors, and the effect of error correction has been greatly improved.

Description of drawings

Fig. 1 is the flowchart of the inventive method;

Fig. 2 is a system structure diagram of the present invention.

Detailed ways

The accompanying drawings are for illustrative purposes only and cannot be construed as limiting the patent;

In order to better illustrate this embodiment, some parts in the drawings will be omitted, enlarged or reduced, and do not represent the size of the actual product;

For those skilled in the art, it is understandable that some well-known structures and descriptions thereof may be omitted in the drawings.

The technical solutions of the present invention will be further described below in conjunction with the accompanying drawings and embodiments.

Example 1

As shown in Figure 1, a BCH+RS cascaded error correction coding method includes the following steps:

S1: Divide the L data to be sent into r columns at the data sending end of the channel, and the data length of each column is m, then L=m×r;

S2: Assuming that the codeword length of the RS code is n, the maximum error correction capability of the RS code is t, and performing RS (n, m, t) encoding on each column of data in the r column data;

S3: Perform BCH (n ₀ , m ₀ , t ₀ ) encoding on the r number data of each row after RS (n, m, t) encoding, and the data sending end sends the encoded data to the channel in the channel The data receiving end sends sequentially, where n ₀ is the data length, m ₀ is the information bit length, and t ₀ is the maximum error correction capability;

S4: Perform BCH (n0, m0, t0) decoding on each column of data received at the data receiving end of the channel. When the decoding is successful, the correct information will be restored. When the decoding fails, the position of the error code word will be recorded. information;

S5: At the data receiving end of the channel, each column of data decoded by BCH (n0, m0, t0) is decoded by RS (n, m, t), and the error position information obtained in S4 is used to delete and decode Encoding method to obtain error-corrected data.

In this embodiment, the length of the data packet is set to 200 bytes, and on the channel, code errors generally include random code errors and burst code errors. Binary BCH can only correct random bit errors, while RS code can correct both random bit errors and burst errors, so the two codes can usually be cascaded. This concatenated code is very effective against a combination of random and burst errors. If a concatenated code is to correct a certain error pattern, the byte error pattern that cannot be corrected by the BCH code must constitute an error pattern correctable by the RS code word. Decentralized random errors are corrected by BCH. Burst errors may only affect a relatively small number of bytes, which can be corrected by RS. According to the characteristics of the RS code, the more supervisory characters, the more correctable errors. Here, t=50, 100 supervisory characters, and 200 bytes of data are divided into two RS (200,100,50) codes. Two sets of RS codewords are interleaved, so that greater performance against burst errors can be obtained. As shown in Table 1, the representation of the encoded structure image is shown in Figure 2. First divide the 200-byte data into two columns (respectively D[1,1], D[1,2]...D[1,100] and D[2,1], D[2,2]...D [2,100] means), 100 bytes per column, RS (200, 100, 50) encoding is performed by column to form two groups of codewords with 200 bytes per column. Then each byte of the RS code word is encoded with BCH (16,8,2), and sent in row order when sending.

Table 1 BCH(16,8,2) and RS(200,100,50) concatenated code structure

D[1,1] V _{D_BCH} [1,1] D[2,1] V _{D_BCH} [2,1] D[1,2] V _{D_BCH} [1,2] D[2,2] V _{D_BCH} [2,2] … … … … D[1,100] V _{D_BCH} [1,100] D[2,100] V _{D_BCH} [2,100] V _RS [1,1] V _{RS_BCH} [1,1] V _RS [2,1] V _{RS_BCH} [2,1] V _RS [1,2] V _{RS_BCH} [1,2] V _RS [2,1] V _{RS_BCH} [2,2] … … … … V _RS [1,100] V _{RS_BCH} [1,100] V _RS [2,100] V _{RS_BCH} [2,100]

Decoding of RS(200,100,50) can adopt deletion decoding method, and the position of deletion can be provided by BCH decoder, which can further improve the success rate of decoding. The concatenated code composed of BCH (16, 8, 2) and two groups of RS (200, 100, 50) discussed in this embodiment can resist a channel bit error rate up to 0.1 with a coding efficiency of 25%. There is still practical value in bit error rate.

Example 2

As shown in Figure 2, a cascaded error correction coding system based on BCH+RS includes a data sending end and a data receiving end located at both ends of the channel; the data sending end includes a serially connected RS encoder and a BCH encoder, and the data receiving end The end includes connecting BCH decoder and RS decoder in sequence; the BCH encoder at the data sending end is connected to the BCH decoder at the data receiving end; the data is sequentially decoded by RS encoder, BCH encoder, BCH decoder and RS The encoder completes the error correction process.

The same or similar reference numbers correspond to the same or similar components;

The positional relationship described in the drawings is only for illustrative purposes and cannot be construed as a limitation to this patent;

Apparently, the above-mentioned embodiments of the present invention are only examples for clearly illustrating the present invention, rather than limiting the implementation of the present invention. For those of ordinary skill in the art, other changes or changes in different forms can be made on the basis of the above description. It is not necessary and impossible to exhaustively list all the implementation manners here. All modifications, equivalent replacements and improvements made within the spirit and principles of the present invention shall be included within the protection scope of the claims of the present invention.

Claims (2)

1. based on a BCH+RS cascade error-correction coding method, it is characterized in that, comprise the steps:

S1: L the data that will send at the data sending terminal of channel are divided into r to arrange, and the data length often arranged is m, then L=m × r;

S2: establishing the code word size of RS code to be the maximum error correcting capability of n, RS code is t, carries out RS(n, m, t to each column data in r column data) coding;

S3: to carrying out RS(n, m, t) coding after often go r logarithmic data carry out BCH(n again ₀, m ₀, t ₀) coding, data sending terminal sends toward data receiver order in the channel by completing the data after coding, wherein n ₀for data length, m ₀information bit is long, t ₀maximum error correcting capability;

S4: BCH(n0 is carried out, m0, t0 to the every column data received at the data receiver of channel) decoding, when successfully decoded, just recover correct information, when decoding failure there is the positional information of wrong code word in record;

S5: will through BCH(n0 at the data receiver of channel, m0, t0) every column data after decoding carries out RS(n, m, t again) decoding, utilize the errors present information obtained in S4, adopt and delete decoding method, obtain the data after error correction.

2. utilize as claimed in claim 1 based on an error correcting coding systems for BCH+RS cascade error-correction coding method, it is characterized in that, comprise the data sending terminal and data receiver that are positioned at channel two ends; Data sending terminal comprises the RS encoder and Bose-Chaudhuri-Hocquenghem Code device that connect in turn, and data receiver comprises and connects BCH decoder and RS decoder in turn; The Bose-Chaudhuri-Hocquenghem Code device of data sending terminal is connected with data receiver BCH decoder; Data complete error correction procedure sequentially through RS encoder, Bose-Chaudhuri-Hocquenghem Code device, BCH decoder and RS decoder.