Space-time Code Selection for OFDM-MISO Systems

A simple space-time code selection scheme for TAD-OFDM systems is proposed. The space-time code for transmission is selected by comparing the equivalent SISO channels with a set of predetermined threshold levels. A threshold level search procedure based on an instantaneous BER constraint, taking into account the feedback information outdate, is described, and sets of threshold levels are proposed as a function of the Doppler frequency. Simulation results show that the system performs well for a range of Doppler frequencies, outperforming both transmit antenna selection and adaptive transmission techniques for high SNRs.