Multiuser detection based on the expectation propagation (EP) algorithm for the massive multiple-input multiple-output (M-MIMO) system has received considerable attention in recent years due to its good performance-complexity tradeoff. However, its performance degrades when the system is highly overloaded. Furthermore, the computational complexity increases fast as the number of receive antennas increases. In this work, we propose an improved EP detector via channel sparsification based approach, which is shortened as S-EP. The key idea is to sparsify the channel first, such that the average degree of the variable node (VN) and function node (FN) in the associated factor graph (FG) is significantly decreased, thus rendering a reduced effective interference. Therefore, the inference accuracy can be enhanced. The associated computational complexity of the message computation can also be eliminated. Analytical and simulation results illustrate that the proposed S-EP based detection scheme achieves noticeable performance gains compared with the conventional EP based one while requiring even a lower computational complexity.

中文翻译：

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基于信道稀疏化的大规模 MIMO 系统的高效 EP 检测器

近年来，基于期望传播（EP）算法的大规模多输入多输出（M-MIMO）系统的多用户检测由于其良好的性能-复杂度权衡而受到广泛关注。但是，当系统高度过载时，其性能会下降。此外，计算复杂度随着接收天线数量的增加而快速增加。在这项工作中，我们通过基于通道稀疏化的方法提出了一种改进的 EP 检测器，简称为 S-EP。关键思想是先对信道进行稀疏化，使得关联因子图（FG）中变量节点（VN）和函数节点（FN）的平均度数显着降低，从而减少有效干扰。因此，可以提高推理精度。也可以消除消息计算的相关计算复杂性。分析和仿真结果表明，与传统的基于 EP 的检测方案相比，所提出的基于 S-EP 的检测方案实现了显着的性能提升，同时需要更低的计算复杂度。