Coding method of code-rate-variable low-density parity-check codes (LDPCs) of which performance approximates to channel capacity
A technology of LDPC code and channel capacity, which is applied in the field of variable code rate LDPC code coding and channel coding, which can solve the problems of difficult performance optimization and limited optimization space, and achieve convenient performance optimization, flexible code length change, and code rate flexible effects
Inactive Publication Date: 2014-03-12
XIDIAN UNIV
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[0007] The purpose of the present invention is to address the problem of difficult performance optimization of concatenated Zigzag codes due to the limited optimization space. Using precoding technology, a variable code rate LDPC code encoding method approaching channel capacity is proposed to realize the optimization of concatenated Zigzag codes. code optimization
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[0039] refer to figure 1 and figure 2 , the concrete encoding steps of the precoding concatenated Zigzag code encoding method that the present invention proposes are as follows:
[0040] Step 1, optimize the value of the parameter γ in the precoder, γ is the ratio of the number of information bits entering the first branch of the precoder to the length N of the information bit group:
[0041] First, with a step size of 0.01, gradually increase γ from 0 to 1 to obtain 101 values, namely {0, 0.01, 0.02, ..., 0.99, 1.00};
[0042] Secondly, for each value of γ, according to the density evolution algorithm, calculate the decoding threshold under the value of γ;
[0043] Then, among the obtained 101 decoding thresholds, find the decoding threshold with the smallest value, and use the value of γ corresponding to the decoding threshold as a temporary optimization result;
[0044] Finally, assign the temporary optimization result to γ, and fine-tune the value of γ so that the valu...
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The invention discloses a coding method of code-rate-variable low-density parity-check codes (LDPCs) of which the performance approximates to the channel capacity, and mainly solves the problem of difficulty in performance optimization of the prior concatenated Zigzag codes, which is caused by limitation on space optimization. The coding method is realized through the following steps: firstly, a parameter Gamma of a precoder is optimized; subsequently, an information bit group is divided into two subgroups, wherein one subgroup is coded via an accumulator, and a coding result is combined with the other subgroup to serve as output of the precoder; afterwards, the output of the precoder is sent into concatenated Zigzag code coders to be coded, and check bit groups are obtained; and finally, the information bit group is combined with the check bit groups to form code words. The LDPC codes obtained through the method are named as pre-coding concatenated Zigzag codes, and the pre-coding concatenated Zigzag codes can conveniently realize performance optimization and support various code rates. A density evolution computational method and a computer simulation result show that decoding thresholds of the pre-coding concatenated Zigzag codes approximate to a Shannon limit, and the pre-coding concatenated Zigzag codes have excellent performance at different code rates and different lengths.
Description
technical field [0001] The invention belongs to the technical field of digital communication and relates to channel coding technology, in particular to a coding method of variable code rate LDPC code whose performance is close to channel capacity. The channel code generated by the coding method can be used as a forward error correction coding technology in wireless mobile communication and other communication occasions where channel conditions vary with time. Background technique [0002] In wireless mobile communication systems, channel coding technology is one of the key technologies to realize reliable communication. The channel conditions of wireless mobile communication systems are time-varying due to user movement and changes in the surrounding environment. In order to obtain higher system throughput in this time-varying communication scenario, it is generally required that the system can flexibly change the code rate of the channel coding to adapt to the time-varying...
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IPC IPC(8): H03M13/11
Inventor 童胜白宝明郑慧娟李琪
Owner XIDIAN UNIV