EM Combination Channel Estimation Algorithm for Interleave-Division Multiple Access Systems

A new channel estimation approach based on expectation maximization (EM) algorithm is proposed for the interleave-division multiple access systems (IDMA). The combination channel estimation is used in the proposed algorithm. The pilot sequences are used to estimate the channel information at the first iteration. The pilot and the soft estimates from the decoders are combined to refine the channel coefficients in the following estimation iterations. The proposed approach greatly reduces the complexity. The simulation results indicate that the bit-error-rate performance of the proposed algorithm is very close to that of ideal channel estimation and the algorithm based on posteriori information is more accurate than that using extrinsic information.