Efficient SFBC-OFDM technique for broadband cooperative wireless networks over mobile channels

Cooperative diversity is a transmission technique that utilizes distributed relays to improve power and spectral efficiencies by creating virtual a antenna arrays. A major challenge in cooperative systems is the time varying nature and the frequency selectivity of cooperative links. In this paper, we propose a novel technique to enhance the bit error rate (BER) performance of cooperative transmission systems with space-frequency block coded (SFBC) orthogonal frequency division multiplexing (OFDM). We assume the Amplify-and-Forward (AF) protocol jointly with the cooperative transmission protocol in. The proposed scheme eliminates the error floor caused by the difference in frequency response of the channel over two adjacent subcarriers due to the channel frequency-selectivity. Extensive Monte Carlo simulation results show that the system can reduce the BER error floor as compared to the conventional cooperative SFBC-OFDM systems.