Channel estimation using a reduced rate of pilot subcarriers for OFDM systems over doubly-selective channels

This study presents an improved channel estimation method for orthogonal frequency division multiplexing (OFDM) over doubly-selective channels. Channel variation has been approximated by the basis expansion model using a specific comb-type pilot approach. Since the data are transmitted as successive symbols in OFDM systems, the authors derive a channel estimation technique exploiting the additional information provided by adjacent symbols pilots. The main idea of the proposed method is to reduce the pilots to useful data ratio in order to improve the effective throughput and to increase the model accuracy in high mobility situations. The proposed algorithm has been investigated by considering both the conventional linear minimum mean square error and the least squaresestimator. Various simulations have been conducted by considering different pilot rates with high Doppler effects and additive white Gaussian noise. The obtained results, in terms of the mean square error and binary error rate, show that the proposed algorithm outperforms the conventional techniques which are based on comb pilot-assisted estimation.