Channel Estimation for OFDM In Time-Variant Multi-Path Environment

In this paper, we address the problem of channel estimation in time-variant multi-path environment in Orthogonal frequency division multiplexing systems(OFDM). Based on the assumption that the channel varies in a linear fashion during an OFDM block duration, a novel iterative channel estimation arithmetic with noise and interference suppression using pilot tones is investigated. Through iterative noise and interference suppression to determine the positions of channel taps, then we compute the time averages and slopes of that to get the time domain channel matrix, so such method can improve the precision of the estimation. To increase the spectral efficiency and reduce the computational complexity, assuming the positions of channel taps are not changed in one frame duration, a frame based on such estimation scheme is presented. Along with the channel estimation technique, we also analyze the optimum pilot tones placement. Theoretical analysis and simulation results show that our assumption is reasonable, and the proposed channel estimation arithmetic has a good performance with low computational complexity and high spectral efficiency.