Construction method for multi-code low density verification LDPC code with fixed code length

Abstract

The invention discloses a construction method for a multi-code rate low density verification LDPC code with a fixed code length, comprising steps of determining the number N of columns of a circulation coefficient array C according to a maximum bitrate of the multi-rate LDPC code to be constructed, choosing a prime number P greater than the column number N, determining the size L of a circulation replacement array and the code length n, constructing a limited domain according to the prime number, choosing a primitive element alpha on a limited domain to determine the circulation coefficient array Ck, utilizing an optimized algorithm to determine that the R is equal to three mask matrixes Bk of the LDPC code with various rate Rk, determining a basic matrix Dk of each code rate according to the circulation coefficient matrix Ck and the mask matrix Bk of each code rate, determining a check matrix Hk of the LDPC code of each code rate according to the basic matrix, and finally obtaining a group of check matrixes of the multi-rate LDPC code. Compared with the prior art, the code length of the constructed multi-rate LDPC code is fixed, and the invention can directly use the check matrix to perform coding, is easy to realize the hardware and is applicable to the satellite communication system and the cellular system.

Description

technical field [0001] The invention belongs to the technical field of wireless communication, in particular to a construction method of a multi-code-rate low-density check LDPC (Low-DensityParity-CheckCodes) code with fixed code length, which can be used in military communication systems, satellite communication systems and cellular communication systems multi-rate error control codes. Background technique [0002] In order to perform reliable transmission on time-varying or interfering channels, a set of LDPC codes with flexible code rates is needed. When the channel conditions are good, use codes with high code rates to improve transmission efficiency; when channel conditions are poor When using codes with a low bit rate to ensure transmission reliability. If the codes of each code rate have different code lengths, the data grouping method or the transmission frame length must be changed during specific transmission, which will increase the overall complexity of the comm...

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Problems solved by technology

[0003] The earliest method of constructing a multi-rate LDPC code with a fixed code length is the row merge technology proposed by scholars such as AndresI.VilaCasado in "Multiple-RateLow-DensityParity-CheckCodeswithConstantBlocklength". Merge some check nodes into one check node to obtain high code rate codes, and add and delete some edges in the Tainer graph according to the optimal degree distribution to improve performance, but when the generated high code rate codes are corrected When the test matrices cannot be combined or do not satisfy the constraints of the ring, it is necessary to regenerate the mother code with a low code rate, which makes the code construction process very complicated, and even a set of codes that satisfy all conditions cannot be obtained.

In 2011, XueqinJiang and other scholars used the hyperplane-based row decomposition method to construct a multi-rate LDPC code with a fixed code length in "Construction of Multiple-RateQuasi-CyclicLDPCCodes via the Hyperplane Decomposing", that is, first construct a high-rate LDPC mother code, and then use the algebraic method A check node is decomposed into more check nodes to obtain a code with a low code rate, but the check matrix obtained by this method does not have a structure that is easy to encode quickly, which makes the encoding complexity higher

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