A robust decision-directed channel estimator for OFDM systems

This paper deals with the estimation of channel frequency response in orthogonal frequency division multiplexing (OFDM) systems. Since existing DD estimators such as LS estimator and the MMSE estimator do not appropriately reduce the influence brought by incorrect decision, and hence suffer from error propagation. Then, in order to mitigate error propagation in DD channel estimation, a DD estimator based on iterative LMMSE is proposed. The algorithm takes the error vector as innovation for the current channel state information (CSI), then calculates the impact that the innovation brings to the current CSI estimation according to the orthogonallity principle and then modify the current CSI, thereby the effect induced by error can be reduced. Simulation results show that the proposal can effectively track the time variations in both the Multipath channel and AWGN channel.