Channel Estimation for Filtered OFDM Systems in Frequency Selective and High Speed Multipath Channels

This paper investigates least squares channel estimation algorithm performance for Filtered Orthogonal Frequency Division Multiplexing (FOFDM) under the frequency selective Rayleigh multipath channel propagation environment. The wireless channel experiences Doppler frequency shift and it causes shift in the subcarriers frequency spectrum. In order to mitigate the effect of Doppler shift in the FOFDM symbol, without carrier synchronization, the larger subcarrier spacing is used. The future wireless communications systems, known as 5G, are expected to be operating at higher GHz bands and there the subcarrier spacing can be selected as large as possible to reduce the Doppler effect during the transmission. Under the high Doppler shift existence in the frequency selective channel, Least Squares estimation results show that in FOFDM system the estimator performance is better when the interval between the center frequency of consecutive subcarriers is selected larger comparing to the conventional subcarrier space.