EM-based angle-domain channel estimation for MIMO-OFDM systems

This paper presents an expectation-maximization (EM) based angle-domain algorithm (EMA) channel estimation for multiple-input multiple-output with orthogonal frequency division multiplexing (MIMO-OFDM) systems. Although EM algorithm combined with maximum a posteriori (MAP) estimator could obtain good performance, its high complexity makes this algorithm unpractical. The proposed algorithm do not require prior knowledge of the channel correlation, avoids inversion induced by LS algorithm and exploits channel coefficients irrelevance in angle domain for ignoring the small-valued channel taps and retaining only the most significant taps (MST) to reduce the effect of noise on the estimates. Simulation results indicate that the proposed algorithm gets better performance than phase shifted orthogonal LS (PSO-LS) and EM algorithms.