Performance Comparison of Channel Estimation Techniques for Mobile Communication Systems

Abstract

In this paper, the performance comparison of channel estimation techniques for Direct Sequence CDMA systems over a frequency selective fading channel disturbed by additive white Gaussian noise (AWGN) is presented. Three types of channel estimation techniques, including moving averaging (MA), minimum mean square error (MMSE) and maximum signal-to-noise ratio (MAXSNR), are presented, and a special attention to the MA approach is paid with optimal averaging interval because of its implementation simplicity and performance is very close to the other two techniques. Since the optimal averaging interval of the MA approach varies with different channel fading rate characterized by the Doppler-shift, a Doppler-shift estimation and its modification are therefore proposed and analyzed, resulting in an asymptotic Doppler-shift estimate which is shown to be working properly at lower SNR and in a large Doppler-shift dynamic range. Furthermore, the optimal averaging interval of the MA approach, obtained by minimizing the mean-squared error of the channel estimate is introduced by means of the frequency domain analysis. Simulation results show that the proposed adaptive channel technique can provide much better channel estimation accuracy with a slight increase in computational complexity, which enables RAKE receiver to achieve better performance when the mobile user suffers from various Doppler-shift rates.