Two-dimensional pilot-aided channel estimation for wireless OFDM systems over severe frequency-selective fading environments

Orthogonal frequency division multiplexing (OFDM) technique is effective and powerful in high data rate digital transmission due to its spectral efficiency, robustness in multipath propagation environments and ability to cope with intersymbol interference. Channel estimation is a crucial problem in coherent OFDM systems, and the various estimation techniques with particular pilot arrangements have been investigated recently. In this paper, a two-dimensional pilotaided channel estimation technique is developed for wireless OFDM communications under severe frequency-selective fading channels. By applying least-square (LS) estimation for the leading pilot symbol in time domain, the channel statistics can be obtained and preserved. And then, LS estimation is also applied for the following regular pilot tones in the OFDM data symbol. Based on the variation of the two LS estimates in the time domain, a novel two-dimensional pilotaided channel estimation algorithm is presented. From the simulation results, the proposed channel estimation scheme has superior performance in the severe frequency-selective fading channels, especially in high SNR. Even if the mobile speed rises, the proposed algorithm still achieves excellent performance.