Quasi-orthogonal space-frequency block code

Orthogonal frequency division multiplexing (OFDM) with space frequency block code (SFBC) outperforms OFDM with space time block code (STBC) in the fast fading channel environment. However, a complex orthogonal code with code rate one does not exist for more than two antennas. To increase the throughput, we propose a quasi-orthogonal SFBC-OFDM system with the four transmit antennas. Simulation shows a tradeoff between the advantage of the SFBC in the mobile communication environment and the improved throughput which achieves code rate one.