Abstract: In amplify-and-forward(AF) OFDM cooperative communication system, since the channel between the first hop(sourco-relay) and the second hop(relay-destination) varies independently,proper subcarrier mapping(SCM) strategy at the relay node has been shown to improve the average end-to-end capacity evidently. However SCM has a poor performance at the condition of low signal-to-noiscratio(SNR)，which is worse than direct transmission. To solve this issue, assuming that perfect channel knowledge is available at the destination node, an adaptive transmission scheme based on subcarrier mapping was proposed for the OFDM-based cooperative communications in this paper. hhe adaptive transmission scheme, which is based on instantaneous channel state information, was selected to offer maximum the end-to-end system capacity. The simulation results show that the proposed solution can evidently improve end-to-end system capacity and achieve better performance of outage probability and symbol error rate.

Key words: Cooperative communication,Orthogonal frectuency division multiplexing,Subcarrier mapping