MMSE channel estimation using two-dimensional filtering in rapid time-variant environments

The performance of orthogonal frequency division multiplexing (OFDM) deteriorates in a rapidly time-varying environment due to the loss of orthogonality, resulting in intercarrier interference (ICI). Moreover, the quality of a model-based channel estimation may degrade if the estimator has been designed for a time-invariant scenario. In this paper, we propose a new pilot-symbol-aided channel estimator based on two-dimensional Wiener filtering for OFDM systems and derive the filter for a rapid time-variant WSSUS channel model. Since the channel statistics are usually unknown, we also analyze the performance loss due to an improper estimation filter, which suffers from the problem of model mismatch.