Channel Estimation for Non-Line-of-Sight WiMax Communication System

In this paper, we present an adaptive channel estimation scheme for IEEE 802.16-2004 Wireless Metropolitan Area Network (a.k.a. WiMAX) in the case that the channel impulse response is longer than the cyclic prefix (CP). The scheme is combined with time domain impulse response shortening technique and frequency domain channel equalization. Simulation results show that the shortening algorithm gives the shortening SNR (SSNR) of effective channel is at least 10 times better than the original channel impulse response. The performance of proposed method can satisfy the BER requirement of IEEE 802.16-2004 standard in the non-line-of-sight environment with the highest data rate (20NMz) transmission. We have also found that the better strategy to design a shortening filter is to over-constraint the desired length to much shorter than CP.