  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.
