Time reversal applied to large MISO-OFDM systems

In this paper we study the Time Reversal (TR) technique in a large MISO-OFDM system. This technique has been proven to provide good beamforming gains at a price of a channel estimation availability at the transmitter side. Moreover, the greater the number of transmit antennas, the better the spatial and temporal focusing gains, which makes TR a good candidate for large MISO systems while keeping a low complexity. The capacity of the system and the bit error rate (BER) performances are first derived and simulated and compared with systems applying the maximum ratio transmission technique. The time focusing gain of the TR technique is then exploited to show that the equivalent channel is shortened when the number of antennas increases, allowing a reduction of the guard interval and an increase of the spectral efficiency of the system. Finally, the robustness of the system to channel estimation errors is evaluated by adding simple channel estimation techniques in the system and evaluating the BER performance.