Simplified EM channel estimation in LTE systems

In this paper, an iterative channel estimation algorithm is considered in LTE systems. A simplified expectation maximization (EM) based algorithm is proposed for channel estimation in the frequency do main. In order to deal with "null" sub-carriers in the guard band and make the algorithm simpler, the truncated singular value decomposition method is integrated to EM (TSVD-EM). Together with a simple linear interpolation in time domain, channel estimates are obtained in an iterative way with low complexity. The mean square error of the proposed algorithm is also analyzed, and, based on this analysis, an additional constant variance is proposed to be used in the detection process. Simulation results show that the proposed channel estimation and detection methods have very close performance to the perfect case.