Abstract：Abstract: In order to improve the channel estimation performance for MIMO systems in timevarying channels, a signal model fitting the framework of expectation maximization (EM) algorithm was established based on the KarhunenLoeve basis expansion model(KLBEM). The channel response was estimated in iterative fashion by EM algorithm. In the estimation scheme, the EM iterations and the orthogonality of KLBEM basis functions were introduced to improve the estimation performance and reduce the computational complexity, respectively. The simulation results of 2 by 2 MIMO system show that the proposed scheme convergences after 5 iterations and the estimated channel impulse response is nearly consistent with the actual one. The bit error rate (BER) performance by the proposed scheme is near to that of perfect channel knowledge. At high signal to noise ratio region, the difference between them is lower than 1 dB with 2 dB performance enhancement over the least square channel estimator. The proposed scheme has good estimation performance in timevarying channel conditions.
2013, Vol. 34 
