Achieving Near MAP Performance With an Excited Markov Chain Monte Carlo MIMO Detector
Achieving Near MAP Performance With an Excited Markov Chain Monte Carlo MIMO Detector
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DOI：
10.1109/twc.2017.2750667
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发表时间：
2017-07
影响因子：
10.4
通讯作者：
Jonathan C. Hedstrom;C. Yuen;Rong-Rong Chen-Rong;B. Farhang-Boroujeny
中科院分区：
文献类型：
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作者：
Jonathan C. Hedstrom;C. Yuen;Rong-Rong Chen-Rong;B. Farhang-Boroujeny
我们介绍一种修正的按位马尔可夫链蒙特卡罗（MCMC）多输入多输出（MIMO）检测器的推导。新方法解决了先前报道的MCMC在高信噪比下的停滞问题，且无需与其他检测方法混合或添加启发式温度缩放因子。MCMC算法的另一个常见问题是收敛时间未知，这使得可预测的固定长度实现存在问题。当在一个收敛缓慢的实例上使用的迭代次数不足时，输出对数似然比可能不稳定且过于自信。因此，我们开发了一种方法来识别罕见的收敛缓慢的运行情况，并减轻它们对软输出信息的不良影响。这提高了前向纠错码的性能，并消除了误码率曲线中的特征性误码平底。接下来，通过一种新颖的方式来可视化吉布斯采样器的内部行为，从而识别伪收敛。提出了一种有效且高效的伪收敛检测和规避策略。最后，新的激发式MCMC（X - MCMC）检测器被证明即使在802.11ac WiFi规范所支持的最大MIMO尺寸和调制速率（8×8 MIMO 256正交幅度调制）下，面对具有挑战性、符合实际且高度相关的信道时，也具有接近最大后验概率的性能。
We introduce a revised derivation of the bitwise Markov Chain Monte Carlo (MCMC) multiple-input multiple-output (MIMO) detector. The new approach resolves the previously reported high SNR stalling problem of MCMC without the need for hybridization with another detector method or adding heuristic temperature scaling factors. Another common problem with MCMC algorithms is the unknown convergence time making predictable fixed-length implementations problematic. When an insufficient number of iterations are used on a slowly converging example, the output log likelihood ratios can be unstable and overconfident. Therefore, we develop a method to identify rare slowly converging runs and mitigate their degrading effects on the soft-output information. This improves forward-error-correcting code performance and removes a symptomatic error floor in bit error rate plots. Next, pseudo-convergence is identified with a novel way to visualize the internal behavior of the Gibbs sampler. An effective and efficient pseudo-convergence detection and escape strategy is suggested. Finally, the new excited MCMC (X-MCMC) detector is shown to have near maximum-a-posteriori performance even with challenging, realistic, and highly-correlated channels at the maximum MIMO sizes and modulation rates supported by the 802.11ac WiFi specification, $8\times 8$ MIMO 256 quadrature amplitude modulation.