Joint Carrier Frequency Offset and fast time-varying channel estimation for MIMO-OFDM systems

In this paper, a novel pilot-aided iterative algorithm is developed for MIMO-OFDM systems operating in fast time-varying environment. An L-path channel model with known path delays is considered to jointly estimate the multi-path Rayleigh channel complex gains and Carrier Frequency Offset (CFO). Each complex gain time-variation within one OFDM symbol is approximated by a Basis Expansion Model (BEM) representation. An auto-regressive (AR) model is built for the parameters to be estimated. The algorithm performs recursive estimation using Extended Kalman Filtering. Hence, the channel matrix is easily computed and the data symbol is estimated with free inter-sub-carrier-interference (ICI) when the channel matrix is QR-decomposed. It is shown that only one iteration is sufficient to approach the performance of the ideal case for which the knowledge of the channel response and CFO is available.