Encoding method for low code rate LDPC code

Abstract

The invention discloses an encoding method of low bit-rate LDPC (Low Density Parity Check) code, including the following steps: (1) matrixes Hand H<d> are respectively constructed, the Hmatrix is a diagonal matrix, H<d> is an array matrix with q multiplied by 1 and is formed by q end-around-shift permutation matrixes Q; the permutation matrix Q is composed of b multiplied by b step permutation matrixes Q having row weight and line weight of 1, at most one element of 1 on each diagonal line and the rest elements of 0; (2) an H matrix with the size of equal to bq multiplied b(q+1) is constructed; (3) a check vector cis constructed, cis equal to (pl, 1=1, 2, ..., M)<T>, wherein p1 represents the value of any first check bit, and M is the length of check bit; (4) according to the check vector c=(p1), the inputted information vector c<d> is equal to (dj), and coded code word c=(c<d>c) is obtained. In the method of the invention, an algebraic method used by end-around-shift value of Q permutation matrix leads belief propagation iterative decoding algorithm to be more easily realized in parallel; bidiagonal matrix structural characteristic of Hmatrix can make the low rate LDPC code be encoded in a recursion manner, and have linear time computing complexity. The simulation performance is superior to the performance of the existing low rate error correcting code, thereby being capable of reaching a signal noise ratio of 0.4 dB and having ratio compatibility.

Description

technical field [0001] The invention belongs to the technical field of information theory channel coding, and in particular relates to a coding method of a low code rate low density parity check (LDPC) code. The invention is a technique for improving the reliability of information transmission, which can be applied in multiple wireless communication fields such as space communication, satellite communication, mobile communication and broadband wireless communication. Background technique [0002] First, briefly introduce the research and application status of low-rate codes in the field of error-correcting codes: 1) In 1992, a concatenated code scheme was deployed on the Galileo space station. Its inner code is a convolutional code with a code rate of 1 / 6. The decoding uses a large Viterbi decoder, and the outer code is a variable-length RS code. The operating signal-to-noise ratio of this scheme is E b / N 0 =0.8dB, the bit error rate is P b (E)≈2×10 -7 , the actual codi...

AI Technical Summary

Problems solved by technology

The most primitive low-rate channel coding schemes are Hadamard codes and super-orthogonal convolutional codes. These two types of codes can only provide small coding gains, and they are far away from Shannon's channel capacity limit.

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