Iterative Turbo Channel Estimation for OFDM System over Rapid Dispersive Fading Channel

Current OFDM systems assume the channel is not time varying within one OFDM frame, and use channel estimates obtained from preamble or pilots for data symbols within the same frame. This performs poorly in rapid dispersive fading channel with high mobility. This paper proposes a novel iterative turbo channel estimation to improve the performance of OFDM system over fading channel with both time and frequency selectivity. Unlike the conventional channel estimation techniques only using preamble or pilots, the proposed channel estimation technique makes use of preamble, pilots and soft coded data information in a turbo iterative approach. Mean square error analysis and simulation results show that the proposed channel estimation technique can approach the performance of perfect channel state information (CSI) with fewer pilots insertion.