Adaptive Channel Estimation for MB-OFDM Systems in Multi-Access Interfering Environments

Channel estimation using preamble symbols is very important for demodulation and dynamic resource allocation in OFDM systems. However, if there is an interference source present, the preamble symbols may be corrupted by the interference. This will spoil the accuracy of channel estimation, and will result in severe degradation in the performance of the entire data frame. This work exploits the feasibility of introducing time- domain redundancy into preamble symbols to improve the estimation performance in multi-access interfering environments. Based on this time-domain redundancy property we propose an adaptive select and replace (ASR) scheme to either partially or completely eliminate the interference in the time-domain. By applying the proposed methods, multi-access interference can be efficiently eliminated. Even when there is no interference present, the proposed methods can still improve the estimation performance in a low frequency-selective channel.