Channel estimation based on Non-Equally Spaced Pilot allocation in OFDM system

This paper proposes the modifications in the Least Square (LS) estimator for the Orthogonal Frequency Division Multiplexing (OFDM) over fast fading Rayleigh channels in the presence of the Additive White Gaussian Noise (AWGN) to optimize its performance. The LS estimation has an inherent channel noise that degrades its performance. In our work, modifications in the LS estimator were proposed to reduce the inherent noise and interpolation error. The channel energy has the concentrated nature in time domain. The first set of taps containing almost all of channel energy for the sample spaced channel was considered. The performance analysis of the modified LS (M-LS) estimator was made both for comb-type and Non-Equally Spaced Pilots (NSP). Simulation results revealed the performance improvement of the M-LS estimator with both comb-type pilot arrangement and NSP over conventional LS estimator with one-dimensional interpolation techniques for comb-type pilot arrangement. A M-LS estimator has optimum performance for linearly spaced pilots compared to NSP.