Multiple-RIS assisted low-complexity coverage enhancement approach for mmWave networks

To address the coverage enhancement challenge in blockage-prone Millimeter-Wave (mmWave) networks where instantaneous Channel State Information (CSI) is unavailable, we propose a multiple-RIS assisted low-complexity coverage enhancement approach. Firstly, a gridding-based optimization framework is proposed to discretize the continuous weak coverage area into a set of grids and transform the coverage problem into a deterministic Max-Min SNR problem. Then, a sub-array decomposition and global angle optimization strategy is incorporated, and an Enhanced Dung Beetle Optimizer (eDBO) algorithm is developed to reduce computational complexity and solve the formulated non-convex problem, respectively. Simulation results verify that the proposed framework with eDBO successfully eliminates coverage holes and achieves high-quality uniform coverage, significantly outperforming the benchmarks in both robustness and effectiveness.