Large-girth nonbinary QC-LDPC codes of various lengths

  • Authors:

  • Jie Huang;Lei Liu;Wuyang Zhou;Shengli Zhou

  • Affiliations:

  • Department of Electrical and Computer Engineering, University of Connecticut, Storrs, CT;Wireless Information Network Lab, Department of Electrical Engineering and Information Science, University of Science and Technology of China, Hefei, China;Wireless Information Network Lab, Department of Electrical Engineering and Information Science, University of Science and Technology of China, Hefei, China;Department of Electrical and Computer Engineering, University of Connecticut, Storrs, CT

  • Venue:
  • IEEE Transactions on Communications
  • Year:
  • 2010

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Abstract

In this paper, we construct nonbinary quasi-cyclic low-density parity-check (QC-LDPC) codes whose parity check matrices consist of an array of square sub-matrices which are either zero matrices or circulant permutation matrices. We propose a novel method to design the shift offset values of the circulant permutation sub-matrices, so that the code length can vary while maintaining a large girth. Extensive Monte Carlo simulations demonstrate that the obtained codes of a wide range of rates (from 1/2 to 8/9) with length from 1000 to 10000 bits have very good performance over both AWGN and Rayleigh fading channels. Furthermore, the proposed method is extended to design multiple nonbinary QC-LDPC codes simultaneously where each individual code can achieve large girth with variable lengths. The proposed codes are appealing to practical adaptive systems where the block length and code rate need to be adaptively adjusted depending on traffic characteristics and channel conditions.