Cell-free (CF) massive multiple-input-multiple-output (mMIMO) deployments are usually investigated with half-duplex nodes and high-capacity fronthaul links. To leverage the possible gains in throughput and energy efficiency (EE) of full-duplex (FD) communications, we consider a FD CF mMIMO system with practical limited-capacity fronthaul links. We derive closed-form spectral efficiency (SE) lower bounds for this system with maximum-ratio combining/maximum-ratio transmission processing and optimal uniform quantization. We then optimize the weighted sum EE (WSEE) via downlink and uplink power control by using a two-layered approach: the first layer formulates the optimization as a generalized convex program, while the {second layer} solves the optimization decentrally using the alternating direction method of multipliers. We analytically show that the proposed two-layered formulation yields a Karush-Kuhn-Tucker point of the original WSEE optimization. We numerically show the influence of weights on the individual EE of the users, which demonstrates the utility of the WSEE metric to incorporate heterogeneous EE requirements of users. We show that low fronthaul capacity reduces the number of users each AP can support, and the cell-free system, consequently, becomes user-centric.
翻译:无细胞(CF)大规模多投入-多输出(MIMO)部署通常使用半双倍节点和高容量前导线连接来调查。为了利用全双倍通信(FD)输送量和能源效率(EE)的可能收益,我们认为FD CF MMIIM(FD)系统具有实际有限的前导线连接功能。我们从封闭式光谱效率(SE)中得出这一系统的低边框,其最大拉皮/最大拉皮传输处理和最佳统一量化。我们然后通过下链和上链控制,通过双层方法优化加权总和EEE(WSEEE)(WSEEE) :第一层将优化作为通用的convex(E) 程序,而第层则使用交替式的倍数方向方法集中解决优化问题。我们分析显示,拟议的两层配方能够产生原WSEEEE优化的Karush-Kuhn-Tucker点。我们用量展示了对单个EE用户的重量影响,我们从数字上展示了E用户的每个前导值,从而展示了EFER的用户的通用要求。