Cooperative relay channel with LDPC codes constructed from array codes

Cooperative communication represents a new class of diversity techniques in which multiple nodes each with a single antenna cooperate to generate a virtual multiple-antenna transmission system and thus offer the benefits of spatial diversity. This paper proposes suitable array codes used as low-density parity-check (LDPC) codes to be applied in the cooperative amplify-and-forward (AF) network. A mathematical description of the construction of suitable array codes for a relay fading channel is also presented. Compared with quasi-cyclic (QC) LDPC codes, the array codes have similar encoding complexity and can adaptively generate various desired girth values. This paper shows that array codes with large girths can achieve substantial system performance improvements. Simulation results in this paper show that using array codes as LDPC codes for cooperative relay transmission provides a significant performance improvement over direct transmission. Moreover, it is also shown that its performance is superior to some structured LDPC codes such as QC-LDPC codes, particularly, a coding gain of about 1dB at BER of 10^-3 can be provided over its counterpart.