Comparison of Three Interpolation in OFDM Systems

Abstract

Doppler shift and channel induced fading effects are more likely to induce inter carrier interferences (ICI), which are the challenging research area in the orthogonal frequency division multiplexing (OFDM). This paper uses channel estimation for canceling the effects of ICI from the received signals. One dimensional frequency domain comb-type channel estimation are considered because of its low computational complexity and effective tracking ability of the fast fading channel. The channel at pilot subcarriers are estimated by using zero forcing (ZF) estimator. In this paper an improved and computationally efficient interpolation techniques are proposed for the estimation of channel impulse response at the data subcarriers. Simulation result reveals that the proposed interpolation technique outperforms other one dimensional interpolation techniques. Errors induced by channel results in degradation of the BER performance. Log maximum a posteriori (Log-MAP) decoding algorithm are used for the component decoders in the iterative turbo decoder. Rayleigh fading channel in the presence of AWGN is used to evaluate the performance of the proposed OFDM system.