Link Adaptation Considering Mobility in OFDMA Systems with Multiple Transmit Antennas

Link adaptation is investigated for OFDMA systems with multiple transmit antennas, where the transmission rate is adapted and where the subcarriers to be used and the multiple antenna transmission scheme to be applied are adaptively selected, according to instantaneous SNR and user mobility. The throughputs (defined as the transmission rate multiplied by 1-(outage probability)) of several transmission modes, which are differentiated by their use of subcarriers and multiple antennas, are compared. Numerical examples are presented showing that the best transmission mode depends on the instantaneous SNR, user mobility (or time-correlation of channel), and a rate adaptation scheme.