Selection Transmitting/Maximum Ratio Combining for Timing Synchronization of MIMO-OFDM Systems

In multiple-input multiple-output orthogonal frequency division multiplexing (MIMO-OFDM) systems, timing synchronization is important in order to find the correct start of OFDM frames and symbols at the receiver. In this paper, a joint transmit antenna selection and maximum ratio combining at the receiver (ST/MRC) are proposed to improve the timing synchronization performance of MIMO-OFDM systems. In this scheme, only the antenna with the highest channel power is selected at the transmitter. The timing metrics of all receive antennas are added together to realize MRC. In order to theoretically investigate the performance of the proposed scheme, the timing metric based on a time-domain repetitive synchronization sequence structure is adopted and the closed-form expression for the correct timing probability in the flat fading channel is derived. Then the proposed ST/MRC scheme for timing synchronization is applied in multipath fading channels. The advantage of the proposed scheme for timing synchronization is verified by simulations.