Frequency synchronization for MIMO OFDM wireless LAN systems

The paper proposes an accurate and time-efficient technique for frequency synchronization of multiple-input multiple-output (MIMO) orthogonal frequency division multiplexing (OFDM) systems. The technique uses a preamble and is thus especially suitable for burst mode communication. The preamble consists of training sequences simultaneously transmitted from the various transmit antennas. From analysis, it is shown that the accuracy of frequency synchronization is close to the Cramer-Rao lower bound and increases for increasing RMS delay spreads and number of receive antennas. Furthermore, application of the proposed algorithm in MIMO OFDM wireless local-area-network (WLAN) systems leads to a BER that is only slightly higher than that of a perfectly synchronized system, making it highly applicable.