Optimal Channel Estimation Algorithms for OFDM over Markov Channels

This paper considers the problem of channel estimation for OFDM systems, where the channels are frequency-and time-selective. Incorporating a Markov model for the time-correlation property of the channel, we propose three optimal channel estimation algorithms in the sense of MMSE; preamble-aided scheme, pilot-symbol-aided modulation (PSAM) scheme and combination of these two schemes. In addition, the reliable decision feedback symbols (RDFS) are exploited to refine the channel estimate, where the RDFS is a decision symbol experiencing a low symbol error rate. Three proposed algorithms taking advantage of RDFS give a more accurate channel estimate and a lower bit error rate. Simulation results verify the proposed algorithms under several channel conditions.