Adaptive receiver beamforming for diversity coded OFDM systems: Maximum SNR design

Over the recent years, advance multiantenna transmission schemes have attracted considerable interest due to their potential benefits in improving the system capacity and error-rate performance. As a result, space-time coding and transmit beamforming have emerged as the two most promising techniques. Because of limited space at the mobile station (MS) and the fact that download intensive services are to be introduced in the next generation of cellular systems, most of research efforts have been pouring on transmit diversity techniques. In this paper, we focus on adaptive uplink transmission and reception techniques for wireless communications and introduce a new frequency-time encoding scheme that can be used to exploit frequency diversity branches for broadband OFDM systems with only one antenna at the MS. By incorporating this with receive beamforming at the base station (BS), the instantaneous signal-to-noise ratio (SNR) is maximized and the system error-rate performance is then further improved. Numerical results showed that systems employed the proposed transceiver structure have a 4-dB improvement over the conventional space-time coding scheme when two receive antennas are used.