Study On Synchronization For MIMO Systems

The synchronization issue of MIMO (Multiple Input Multiple Output) systems is studied in this paper in the condition that all the time-delay and frequency-offset from different transmitting and receiving antenna pairs are the same. The primary research concentrates mainly on the frequency synchronization. First a novel frequency-offset estimator based on best-weighted correlations is proposed. By using periodic training sequences the algorithm calculates the correlations of received signals and weights the results properly to estimate the frequency-offset. This method allows for a flexible trade-off between the MSE (Mean Square Error) and the computational load. It is further proved that the proposed algorithm can asymptotically attain the low bound of MSE with the optimum parameter selected and can be considered as an asymptotically optimal frequency-offset estimator in MIMO systems. Moreover, we focus on IEEE 802.11n WLAN (Wireless Local Area Network) standard, the physical layer of which describes a transmitter for the MIMO systems and is deemed to be used in next generation WLANs. In this paper a corresponding receiver is investigated based on this standard with emphasis on the synchronization scheme which is improved from IEEE 802.11a systems by combined signal processing on multiple antennas. Finally the performance of the receiver is evaluated by simulation.