Simple Low-Rate Non-Binary LDPC Coding for Relay Channels

Binary LDPC coded relay systems have been well studied previously with the assumption of infinite codeword length. In this paper, we deal with non-binary LDPC codes which can outperform their binary counterpart especially for practical codeword length. We utilize non-binary LDPC codes and recently invented non-binary coding techniques known as multiplicative repetition to design the low-rate coding strategy for the decode-and-forward half-duplex relay channel. We claim that the proposed strategy is simple since the destination and the relay can decode with almost the same computational complexity by sharing the same structure of decoder. Numerical experiments are carried out to show that the performances obtained by nonbinary LDPC coded relay systems surpass the capacity of direct transmission and also approach within less than 1.5 dB from the achievable rate of the relay channels.