MMB系统中HS-LDPC编码的实现

Low density parity-check (LDPC) code is, currently, one kind of sparse parity-check matrix based linear block error-correcting codes which could highly approach the Shannon limit with iterative decoding. LDPC codes’ superior performance, which may surpass Turbo code, makes it suitable for transmitting large amount of data in multimedia broadcasting system. CMMB is the first multimedia broadcasting system in China that is targeted at handheld devices with small screens, such as mobile phones and PDA. For its superior performance, CMMB uses LDPC as its channel coding. Moreover, CMMB adopts OFDM as its means of transmission, which make it more resistant to interference. The kind of LDPC code in CMMB is a high-structured LDCP code (HS-LDPC). Relatively small amount of computing is involved for HS-LDPC decoding in mobile terminals, which is beneficial for the life span of the batteries in the terminals. However, the encoding of HS-LDPC codes requires a comparatively demanding amount of computing. This paper provides an algorithm that is based on the LU decomposition of the parity check matrix H of the HS-LDPC codes. This real-time algorithm is very efficient and is implemented and run in common micro-computers. The performance of this algorithm is shown in the final part of this paper.