A Study on Channel Estimation Using EM Algorithm for Mobile WiMAX Systems

Abstract

Mobile WiMAX system has recently been popularized as one of high speed wireless communication techniques. It is, however, necessary to accurately estimate the time-variant channel in order to equalize the received signal from the moving vehicular at high speed. In this paper, we propose a novel channel estimation method using the Expectation-Maximization (EM) algorithm for the uplink PUSC (Partial Usage of SubChannels) mode of the mobile WiMAX system in time-varying multi-path channels. The proposed algorithm estimates the channel frequency responses among the data signal subcarriers based on the estimates of the channel frequency responses on the pilot signal subcarriers. We assume that the estimate of the channel response at the data signal subcarrier is given by a linear combination, whose combination coefficients are determined using the EM algorithm, of the estimates of the channel responses among the pilot signal subcarriers. By computer simulations, we evaluate performances of the proposed algorithm in comparison with the conventional linear interpolation algorithm.