Journal on Communications ›› 2017, Vol. 38 ›› Issue (4): 76-85.doi: 10.11959/j.issn.1000-436x.2017083

• Papers • Previous Articles     Next Articles

Efficient algorithm for calculating short cycles in Tanner graph based on matrix computation

Qing ZHU1,Le-nan WU2,Yong-biao YANG1,Jie LI1,Shi-ming XU1   

  1. 1 NARI Technology Development Co.,Ltd.,Nanjing 211106,China
    2 School of Information Science and Engineering,Southeast University,Nanjing 210096,China
  • Revised:2017-03-02 Online:2017-04-01 Published:2017-07-20
  • Supported by:
    The National Natural Science Foundation of China(61233007)

Abstract:

Loop distribution of Tanner graph affects the BER performance of low-density parity-check codes(LDPC) decoding.To count short cycles in the Tanner graph efficiently,a side by side recursion algorithm based on matrix computation was proposed.Firstly,5 basic graph structures were defined to realize recursive calculate in the implementation process.Compared with previous works,the algorithm provided many methods for counting the same length of cycles.The same result confirmed the correctness of the algorithm.The new algorithm could not only calculate the total number of cycles,but also gave the number each edge participating in fixed-length cycles.Its complexity was proportional to the product of D and square of N,where D was the average degree of variable nodes,and N denoted the code length.For LDPC codes,D was far less than N.For most of the LDPC codes,the calculation for numbers of cycle-length g、g+2、g+4 was only several seconds.

Key words: Tanner graph, low-density parity-check codes (LDPC), short cycle, girth

CLC Number: 

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