A multistage channel estimation and ICI reduction method for OFDM systems in doubly dispersive channels

Rapidly time-varying channels degrade the performance of the orthogonal frequency division multiplexing (OFDM) due to loosing the orthogonality between the sub-carriers resulting in inter-carrier-interference (ICI) and necessitate estimating the complete elements of the channel matrix. In this paper a low complexity multistage pilot-based channel estimator is introduced, in which, the time delays and number of paths are first estimated using a super resolution technique. The main diagonal of the channel matrix is estimated via Wiener filtering. The whole channel matrix which is used for ICI cancellation is built by applying a linear interpolation to approximate the channel time variation between three successive symbols.