An Iterative Decoding Algorithm with Backtracking to Lower the Error-Floors of LDPC Codes

作者：Kang Jingyu^*; Huang Qin; Lin Shu; Abdel Ghaffar Khaled

来源：IEEE Transactions on Communications, 2011, 59(1): 64-73.

DOI：10.1109/TCOMM.2010.101210.090628

• LDPC code
• message-passing algorithm
• error-floor
• trapping set
• backtracking

Error-floors are the main reason for excluding LDPC codes from applications requiring very low bit-error rate. They are attributed to a particular structure in the codes' Tanner graphs, known as trapping sets, which traps the message-passing algorithms commonly used to decode LDPC codes, and prevents decoding from converging to the correct codeword. A technique is proposed to break trapping sets while decoding. Based on decoding results leading to a decoding failure, some bits are identified in a previous iteration and flipped and decoding is restarted. This backtracking may enable the decoder to get out of the trapped state. A semi-analytical method is also proposed to predict the error-floor after backtracking. Simulation results indicate the effectiveness of the proposed technique in lowering the error-floor. The technique, which has moderate complexity overhead, is applicable to any code without requiring a prior knowledge of the structure of its trapping sets.

• 出版日期2011-1