Carrier Frequency Offset Estimation in MIMO OFDM Systems

The combination of Multi-Input Multi-Output (MIMO) with Orthogonal Frequency Division Multiplexing (OFDM) is regarded as a promising technique for the future wireless communications. However, the performance of MIMO OFDM systems is very sensitive to carrier frequency offset (CFO) which introduces inter-carrier-interference (ICI). Consequently, CFO estimation plays a key role in MIMO OFDM systems. In this paper, a novel scheme for CFO estimation is proposed, which is based on training sequences composed of repeated pseudo-noise (PN) sequences. In the proposed scheme, single-g estimators are adopted for CFO acquisition to get large estimation range. And, multiple-g estimators are used for CFO tracking to improve estimation accuracy. Simulation results demonstrate that all the estimators in our scheme have superior performance, and are more robust and accurate than Schenk´s scheme [10] [11] both in the AWGN channel and in the multipath channel.