earticle

영어

Cooperative relay systems represent a promising solution overcoming the drawbacks of non-line-of-sight (NLOS) propagation in future wireless communications. In this paper, we propose a cooperative relay coding which uses adaptive hierarchical modulation based on cyclic redundancy check (CRC) and cyclic delay diversity (CDD). In the proposed scheme, the system consists of multiple single-antenna terminals acting as relays and cooperating to provide spatial diversity. Also, cyclic shift is introduced at the relays to increase the frequency selectivity in the relay channels. To exploit a highly selective channel, convolutional code is employed together with orthogonal frequency division multiplexing (OFDM). The proposed scheme is evaluated in terms of the bit error rate (BER).