An encoding scheme and encoder architecture for rate-compatible QC-LDPC codes

We consider the problem of rate-compatible (RC)-encoder and RC-puncturing of LDPC codes. The proposed encoder is based on a modification of MacKay encoding scheme. The introduced modification enables the application of MacKay scheme for quasi-cyclic (QC) LDPC codes combined with a proposed matrix puncturing scheme based on an also proposed parity-check matrix construction to achieve code-rate compatibility. The proposed encoding scheme and VLSI encoder architecture address the problem of encoding complexity, since about 80% of MacKay encoding algorithm complexity is linearly depended on LDPC check node degree. The proposed matrix puncturing scheme can produce good BER performance especially for high puncturing rates, where only a few parity check symbols are transmitted. A comparison with prior art in puncturing is offered, which shows superior performance of the proposed scheme, in terms of coding gain without any hardware cost.