In this paper, we propose low-complexity local detectors and log-likelihood ratio (LLR) refinement techniques for a coded cell-free massive multiple input multiple output (CF- mMIMO) systems, where an iterative detection and decoding (IDD) scheme is applied using parallel interference cancellation (PIC) and access point (AP) selection. In particular, we propose three LLR processing schemes based on the individual processing of the LLRs of each AP, LLR censoring, and a linear combination of LLRs by assuming statistical independence. We derive new closed-form expressions for the local soft minimum mean square error (MMSE)-PIC detector and receive matched filter (RMF). We also examine the system performance as the number of iterations increases. Simulations assess the performance of the proposed techniques against existing approaches.

翻译：本文针对采用并行干扰消除与接入点选择的迭代检测解码方案的无蜂窝大规模多输入多输出编码系统，提出了低复杂度本地检测器与对数似然比精细化技术。具体而言，我们基于各接入点LLR独立处理、LLR截断筛选及统计独立性假设下的LLR线性组合，提出了三种LLR处理方案。我们推导了本地软最小均方误差并行干扰消除检测器与接收匹配滤波器的闭式解析表达式，并分析了系统性能随迭代次数增加的变化规律。仿真实验评估了所提技术相较于现有方法的性能表现。