A novel EM-based MAP channel estimation for MIMO-OFDM systems

For MIMO-OFDM system, expectation maximum (EM) is used to decrease the complexity of maximum a posteriori probability (MAP) channel estimation algorithm. However, EM-based MAP algorithm generates the low mean square error (MSE) performance at high signal noise rate (SNR) because of the convergent feature of EM algorithm. According to this issue, a modified EM-based MAP (MEM-MAP) channel estimation algorithm is proposed. The proposed algorithm improves convergent property of EM algorithm at high SNR by introducing an equivalent model. Then, according to the idea that MIMO channels in angle domain can be assumed to be independent, most significant taps (MST) technique in angle domain is used to improve the MSE performance of MEM-MAP algorithm. Simulation results indicate the effectiveness of the proposed algorithm.