Quasi-Cyclic LDPC Code Design for Practical Applications

Yanhu Shan

A method to construct a flexible length or rate of quasi-cyclic Low Density Parity Check(LDPC) codes based on Balanced Incomplete Block Design(BIBD) and cycle permutation matrix is proposed.Based on actual demand,the corresponding template matrix is constructed by BIBD method.The template matrix is extended by the appropriate cycle permutation matrix.The quasi-cyclic LDPC codes constructed by the proposed method have a good structure and flexibility.This method improves the efficiency of construction good codes which meet the needs of a practical application.Simulations show that quasi-cyclic LDPC codes constructed by the proposed method perform well over AWGN channels with iterative decoding and have a lower error floor.

Xiao Xiao, Lee

Siddarama R. Patil, Sant Saran Pathak

In this paper we propose a novel method for designing irregular quasi-cyclic low-density parity-check (LDPC) codes from Balanced Incomplete Block Designs (BIBDpsilas). The design method hinges around finding the optimum degree profile by minimizing the threshold using density evolution. The approach for designing short block length codes is robust for practical implementation and has been found to exhibit considerable performance gain that may be attributed to a good degree profile for the codes. The design takes into consideration the code rate and code length as variable parameters. The simulation results for the designed codes are compared with regular and irregular quasi-cyclic BIBD based LDPC codes and found a relatively higher performance in terms of BER.

Baihong, Lin -, Yukui +5 more

Keke Liu, Shu Lin, Khaled Abdel-Ghaffar

Cyclic and quasi-cyclic algebraic LDPC codes constructed based on finite fields, finite geometries, and combinatorial designs can achieve excellent performance in terms of error rate, error floor and rate of decoding convergence with iterative decoding. However, the relatively high density of the parity-check matrix of an algebraic cyclic or quasi-cyclic LDPC code makes the hardware implementation complexity of the decoder quite large, which may be a critical issue in practical applications. This paper presents an effective reduced-complexity algorithm for decoding algebraic cyclic and quasi-cyclic LDPC codes based on the block cyclic structure and cyclic grouping of the rows of their parity-check matrices. The decoding of a code is carried out based on a single small submatrix of the parity-check matrix of the code in a revolving manner. The proposed decoding algorithm significantly reduces the hardware implementation complexity and the size of memory required to store information.

Nishit Pandya, Abdolhosein Moinian, Bahram Honary