Joint Design of Intelligent Reflecting Surface Configuration and Precoding in MISO-VLC Systems

To address the problem of insufficient user fairness in multi-user multiple-input single-output visible light communication systems, this paper proposes a joint design scheme of intelligent reflecting surface configuration and precoding to maximize the minimum signal-to-interference-plus-noise ratio among users. To tackle the constructed non-convex optimization problem, this paper proposes an alternating optimization algorithm, which alternately fixes the intelligent reflecting surface configuration matrix and the precoding matrix, decomposes the original problem into subproblems that can be transformed into convex forms for efficient solution, and iteratively solves them using the bisection search and relaxation–quantization methods. Simulation results show that, compared with the minimum mean square error and zero-forcing precoding schemes based on distance greedy matching, the proposed method improves the minimum signal-to-interference-plus-noise ratio of users by 12 and 16 percent. Furthermore, when user locations are fixed, the minimum signal-to-interference-plus-noise ratio under the optimal deployment position of the intelligent reflecting surface increases by 8 percent compared with the random user distribution scenario.