The amalgamation of cell-free networks and reconfigurable intelligent surface (RIS) has become a prospective technique for future sixth-generation wireless communication systems. In this paper, we focus on the precoding and beamforming design for a downlink RIS-aided cell-free network. The design is formulated as a non-convex optimization problem by jointly optimizing the combining vector, active precoding, and passive RIS beamforming for minimizing the weighted sum of users' mean square error. A novel joint distributed precoding and beamforming framework is proposed to decentralize the alternating optimization method for acquiring a suboptimal solution to the design problem. Finally, numerical results validate the effectiveness of the proposed distributed precoding and beamforming framework, showing its low-complexity and improved scalability compared with the centralized method.

翻译：无蜂窝网络与可重构智能表面（RIS）的融合已成为未来第六代无线通信系统的一项前瞻性技术。本文聚焦于下行链路RIS辅助无蜂窝网络的预编码与波束成形设计。该设计通过联合优化组合向量、主动预编码与被动RIS波束成形，构建了一个以最小化用户加权均方误差为目标的非凸优化问题。我们提出了一种新颖的联合分布式预编码与波束成形框架，将交替优化方法分散化，从而获得设计问题的次优解。最后，数值结果验证了所提分布式预编码与波束成形框架的有效性，表明其相比集中式方法具有低复杂度和更强的可扩展性。