An Energy-Efficient Cooperative SFBC-OFDM System Using Subcarrier Permutation

Cooperative orthogonal frequency division multiplexing (OFDM) systems have been shown to be fertile in both spatial and frequency diversities and can provide high transmission throughputs. In this paper, we aim at developing a cooperative space-frequency block coded (SFBC) OFDM system by using Alamouti´s coding scheme. With the selective decode-and-forward relaying strategy, we first derive the equivalent channel power gain in a cooperative SFBC-OFDM system based on the channel state information and the predefined transmission rate on each subcarrier. Then, we employ subcarrier permutation to find the optimal pairing mechanism between the broadcasting phase and the forwarding phase such that the total transmission power is minimized. Simulation results show that the proposed cooperative SFBC-OFDM system using subcarrier permutation can provide obvious performance improvement over existing cooperative OFDM systems without SFBC.