Pilot aided frequency offset estimation and channel estimation for MIMO-OFDM systems

Orthogonal frequency division multiplexing (OFDM) has been adopted in various wireless communication standards to exploit its high spectral efficiency and robustness against multipath fading channels. Along with the potential benefits of OFDM transmissions, it is very strict on orthogonality. Otherwise, it will introduce inter-carrier interference (ICI). We focus on how to reduce the ICI due to carrier frequency offset (CFO) in multi-input multi-output orthogonal frequency division multiplexing (MIMO-OFDM) systems in this paper. The influence by residual CFO in the MIMO-OFDM system is analyzed and the residual CFO estimation methods based on pilot subcarriers is presented. According to the simulation results, a proper pilot sequence is selected to make the best performance of the system in the presence of CFO with using the improved methods proposed in the paper.