迭代均衡系统中的一种SNR估计方法
doi: 10.3724/SP.J.1146.2006.01490
A SNR Estimation Method in Turbo Detection System
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摘要: 该文首先分析了最大后敛概率(Maximum A posterior Probability, MAP)迭代均衡及其简化算法Max-Log- MAP(MLM)、缩放软信息的Max-Log-MAP算法(Scaled Max-Log-MAP，SMLM)对SNR估计误差的敏感性问题，然后利用SMLM算法对SNR估计误差不敏感的特性，提出了一种基于SMLM的软输出信息估计信道SNR的方法。最后，利用该算法，还提出了一种新的迭代均衡算法，并研究了其性能，结果表明该算法不仅不需要任何导引符号开销，还能获得非常接近具有理想的SNR的MAP算法的误码性能。Abstract: In this paper, the sensitivity of MAP algorithm and its reduced ones as Max-Log-MAP and Scaled Max-Log-Map to SNR mismatch in turbo detection systems are analyzed. Due to the fact of insensitivity of Scaled Max-Log-MAP algorithm to SNR mismatch, a new SNR estimation method is proposed using the soft output extrinsic information. Then, a new turbo equalization scheme is also provided utilizing the SNR estimation algorithm, and the corresponding performance of new equalization algorithm is also studied. The simulation results show that new equalization scheme with reliability-based SNR estimation method performs very close to MAP algorithm with known SNR, although it does not need pilot symbols.
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