Kalman Filter based Channel Estimation and ICI Suppression for High Mobility OFDM Systems

The use of orthogonal frequency division multiplexing (OFDM) in frequency selective fading environments has been well explored. However, OFDM is more prone to time selective fading as compared to single carrier systems. Rapid time variations destroy the subcarrier orthogonality and introduce inter-carrier interference (ICI). Besides this, obtaining reliable channel estimates for receiver equalization is a non-trivial task in rapidly fading systems. In our work, we have addressed the problem of channel estimation and ICI suppression by viewing the system as a state space model. Kalman filter is employed to estimate the channel; this is followed by a time domain ICI mitigation filter which maximizes the SINR (signal to interference plus noise ratio). This method is seen to provide significant SINR gain with low training overhead.