Rate-compatible root-protograph LDPC codes for quasi-static fading relay channels

Abstract

We investigate the protograph low-density parity-check (LDPC) codes over quasi-static fading (QSF) relay channels with coded cooperation (CC) in this paper. A new construction method is proposed for designing the full-diversity rate-compatible root-protograph (RCRP) codes for such a relaying protocol. The asymptotic word error rate (WER) and bit error rate (BER) of the RCRP codes are analyzed by exploiting a new protograph extrinsic information transfer (PEXIT) algorithm. Furthermore, the expression of outage probability is also developed to characterize the error performance of RCRP codes. Both theoretical and simulated results suggest that the RCRP codes not only outperform the conventional regular rate-compatible protograph (RCP) codes in terms of error performance with code rates ranging from 0 to 1/2 but approach the outage limit as well.