基于修正EM的高效MIMO-OFDM系统MAP信道估计算法

An efficient MAP channel estimation algorithm based on modified EM for MIMO-OFDM Systems

针对MIMO—OFDM系统的基于期望最大化（EM）的最大后验（MAP）信道估计算法带来的误差地板（EF）现象及较低的数据传输效率，提出了一种基于修正EM的高效的MAP信道估计算法。该算法首先引入一种更精确的系统模型来改善基于EM的MAP估计算法在高信噪比下的EF现象，其次利用多个正交频分复用（OFDM）符号进行联合信道估计来提高系统的数据传输效率和信道估计的均方误差（MSE）性能。仿真实验结果表明这种估计算法改善了误差地板现象。同时拥有更低的估计误差和更高的数据传输效率。

Aiming at the problem that the maximum a posteriori （MAP） channel estimation algorithm based on the expectation maximum （EM） for MIMO-OFDM systems generally suffers from the error floor （EF） phenomenon and the low efficiency in data transmission, the paper proposes an improved MAP channel estimation algorithm based on the modified EM, which is more efficient in data transmission. The new algorithm introduces a more accurate system model so as to improve the EF phenomenon caused by the EM-based MAP estimation algorithm in high signal-to-noise ratio （SNR） systems, and uses multiple OFDM symbols to implement the joint channel estimation to enhance the data transmission efficiency and improve the mean square error （MSE） performance. The simulation results show that the proposed algorithm can weaken the EF phenomenon, lower the estimation MSE, and raise the data transmission efficiency.