Coding method of low density oven odd check code

Abstract

This invention discloses an encoding method for a low density odd-even check code including: 1, determining code rate R and a code length N and computing the check bit length M, 2, constructing the H to the power p matrix of MxM, 3, determining the structure parameter line weight t of the H to the power d, rank weight q and a sub-matrix dimension u, 4, utilizing the arithmetic sequence to comprise the vector v to constitute matrix D finally, 5, the D matrix and a group of its orthogonal D matrix group constitute matrix H to the power d, 6, evaluating the code sequence c and construct the H matrix, H=H to the power p:H to the power d.

Description

technical field [0001] The invention belongs to the technical field of information theory channel coding, and specifically relates to a coding method of a low-density parity check (LDPC) code. The invention is compatible with 3G mobile communication standards and is mainly used for broadband wireless multimedia communication. Background technique [0002] In the more than 50 years since Shannon established information theory, channel coding theory has been widely used in many fields such as deep space communication and satellite communication, data transmission, data storage, mobile communication, file delivery and digital audio and video transmission. And thus produced five types of standards, namely, space data system coding standards for deep space and satellite communications, trellis coding standards for high-speed data modulation and demodulation, RS coding standards for disk compression storage systems, mobile cellular Communication coding standard, CRC coding standar...

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Problems solved by technology

Some representative research results on the algebraic construction method of H matrix are as follows: 1) MacKay, the rediscoverer of LDPC codes, proposed a method of searching random rule LDPC codes by computer, and randomly generated H matrix without 4-line cycle. The code rate is 1 / 2, and the code length is greater than 10 4 , the performance is about 1.5dB away from the Shannon limit. He did not propose an algebraic construction method for regular LDPC codes. Random codes have only theoretical research value and no practical application value; 2) Yu Kou and Heng Tang proposed LDPC codes based on finite geometry , Bane Vasic and Bassem Ammar proposed to use the branch of combinatorics - Balanced Incomplete Block Design (BIBD) to construct LDPC codes. The disadvantage of these two types of algebraic structure LDPC codes is that the change of coding parameters is not flexible enough. Given the value of the code length and code rate, then construct the H matrix, but first construct the H matrix according to the algorithm rules, and then determine the code parameters according to the H matrix. The code parameters determined in this way are difficult to be compatible with the existing standards. These two types of codes are used in When the code rate is high and the packet length is long, it has good performance; 3) Gallager only gave the construction algorithm of the (N, 3, 4) specific structure LDPC code sparse parity check matrix H in his doctoral thesis, and its H The block sub-matrix in the matrix is ​​composed of the identity matrix and a group of cyclic shift matrices. It is currently called quasi-cyclic LDPC code (QC-LDPC code). He does not give the structure of the sparse parity check matrix H of any structure. method, and did not propose the design method of the encoder. R.M.Tanner and Marc.P.C.Fossorier conducted in-depth research on QC-LDPC codes on the basis of Gallager's research. Their basic idea is: H matrix consists of a set of block matrices The regular arrangement of this set of block matrices consists of the identity matrix and a set of cyclic shift matrices of the identity matrix

The restriction on u makes the code rate parameter selection of QC-LDPC codes inflexible. For example, it is not possible to design codes with a code rate of 0.5, and the performance of QC-LDPC codes is 3-5dB, which does not seem to be very good

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