The Study on Cooperative Relay Coding in Multicarrier System
Cooperative relay systems represent a promising solution overcoming the drawbacks of Non-Line-Of-Sight (NLOS) propagation in future wireless communications. In this paper, the authors 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, convolution code is employed together with Orthogonal Frequency Division Multiplexing (OFDM). The proposed scheme is evaluated in terms of the Bit Error Rate (BER).