Finite-length rate-compatible LDPC codes based on extension techniques

We propose two innovative extension schemes for Rate-Compatible (RC) Low-Density Parity-Check (LDPC) codes with short/moderate block lengths. The proposed designs are based on the counting cycles algorithm and the Approximate Cycle Extrinsic Message Degree (EMD). Our layer-structured extension schemes enjoy a linear-time encodable ability and relatively low decoding complexity thanks to low degree profiles with limited decoding iterations, such that they intrinsically fit in a type-II hybrid automatic repeat-request (ARQ) system. Simulation results show that the proposed approaches manage to yield a performance gain of up to 0.3 dB when compared to the existing extension technique.