MIMO-OFDM系统中一种改进的Bayesian EM信道估计器
doi: 10.3724/SP.J.1146.2007.00095
An Improved Bayesian EM Channel Estimator for MIMO-OFDM Systems
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摘要: 该文提出了MIMO-OFDM系统中一种改进的Bayesian EM信道估计器。利用软球形译码器的搜索列表和解码器反馈的先验信息对传统EM信道估计中的软信息近似处理进行了修正，计算了更为准确的软符号后验概率分布以及一阶、二阶统计量。基于初始估计得到的信道先验信息，设计了新的考虑软符号后验互相关的时域信道冲激响应最大后验概率(MAP)估计算法。仿真试验结果表明：该算法和传统EM信道估计算法相比具有更低的误码率和更小的估计均方误差值。Abstract: An improved Bayesian EM channel estimator is proposed for MIMO-OFDM systems. Using the candidates list of the List Sphere Decoder (LSD) and a prior information from the decoder, the approximations of the soft decision symbols in the conventional EM channel estimator are modified. The a posteriori probabilities, the first and second moments of the soft symbol decisions are calculated more accurately. Based on the prior information of the channel measured by the initial estimation, a new Maximum A Posteriori (MAP) estimation of the channel impulse response, which considers the posteriori cross-correlation of the soft symbols, is obtained. Simulation results show that the newly proposed BEM algorithm outperforms conventional EM estimation schemes both in terms of BER and mean square estimation error.
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