Low-Complexity Channel Estimation for Wireless Block Transmission Systems in Time-and Frequency-Selective Rayleigh Fading Channels

摘要

Mobility-induced Doppler spread and multipath propagation introduce the time- and frequency-selectivity (doubly selectivity) in fading channels. Based on the complex exponential basis expansion model (BEM) to approximate the doubly selective channel (DSC), a low-complexity channel estimation scheme for block transmission systems over DSC are developed in this paper. Using the developed scheme, the long data block is divided into a few short data subblocks in terms of the maximum normalized Doppler frequency and block length, and each subblock is performed to respective channel estimation. Thus the total calculation complexity is effectively decreased because the number of the BEM channel coefficients to estimate is greatly reduced for each sub-block. Moreover, by utilizing these channel estimation values to refit the true channel, we can obtain better channel estimation. Besides, the normalized mean square error (NMSE) expressions for the developed scheme and the existing scheme are derived in detail, respectively. Compared to the existing scheme, the proposed scheme has lower calculation complexity and superior performance. The simulation results verify the effectiveness of the developed scheme, and the theory values of the derived NMSE accord with corresponding simulation values.