A novel channel estimation technique for OFDM systems with robustness against timing offset

A new interpolation based channel estimation technique has been proposed to eliminate the effect of phase rotation caused by symbol timing offset (STO) in comb-type pilot-aided OFDM systems. STO is one of the most severe impairments that leads to inter-symbol interference (ISI) and phase rotation of FFT outputs and results in performance degradation in OFDM systems. The main advantage of the proposed channel estimation technique is its insensitivity to the impact of phase rotation. Subsequently, the fine timing synchronization process (which tries to cancel the residual STO) in conventional timing synchronization methods can be eliminated. The main idea behind the proposed technique is to separate the phase and the magnitude components of the estimated channel frequency response at the pilot subcarriers. In this way, two steps of interpolation are performed for the both phase and magnitude, separately and independently. Computational complexity of the proposed channel estimation method is approximately equal to that of the conventional one. Analytical and simulation results of applying the proposed technique to the DVB-T system show that the achieved BER performance is close to that of conventional method in the absence of any timing offset, while in the presence of STO, the proposed technique outperforms the conventional method, considerably.