Network-assisted full duplex (NAFD) is a unified duplex technique for large-scale distributed antenna systems (DAS) with remote antenna units operating in either half-duplex mode or full-duplex mode and all connecting to central processing unit via backhaul links. Downlink sparse beamforming and uplink power control are effective methods to reduce cross-link interference involved in NAFD with finite-capacity backhaul. We study joint downlink beamforming and power control for NAFD by maximizing the aggregated uplink and downlink spectral efficiency subject to quality-of-service constraints and backhaul constraints. Two approaches have been proposed to solve the optimization problem, where the first approach converts the objective function to the difference of two convex functions with semi-definite relaxation, and then, an iterative SDR-block coordinate descent method is applied to solve the problem. The second method is based on sequential parametric convex approximation. Simulation results have shown that the proposed algorithms yield a higher spectral efficiency gain compared to the traditional time-division duplex scheme.

中文翻译：

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具有网络辅助全双工的大型 DAS 的联合稀疏波束成形和功率控制

网络辅助全双工 (NAFD) 是一种用于大规模分布式天线系统 (DAS) 的统一双工技术，远程天线单元在半双工模式或全双工模式下运行，并且全部通过回程链路连接到中央处理单元。下行稀疏波束赋形和上行功率控制是减少有限容量回程NAFD中交叉链路干扰的有效方法。我们通过最大化聚合上行链路和下行链路频谱效率来研究 NAFD 的联合下行链路波束成形和功率控制，这些效率受服务质量约束和回程约束的约束。已经提出了两种方法来解决优化问题，其中第一种方法将目标函数转换为具有半定松弛的两个凸函数的差，然后，应用迭代SDR块坐标下降方法来解决该问题。第二种方法基于序列参数凸逼近。仿真结果表明，与传统的时分双工方案相比，所提出的算法产生了更高的频谱效率增益。