Advanced Scalable Multi-Beam Focusing for Indoor Optical Wireless Networks With IR Radiative Clusters

Optical wireless networks emerge as a promising solution to the ever-growing data demand for user-centric indoor applications. This work demonstrates a novel approach to advance multi-beam radiation patterns in indoor optical wireless networks by utilizing a cluster-based optical aperture comprising IR radiative elements. Spatially distributed IR clusters permit a non-uniform spherical wave model to focus the radiation in the near-field regime. By executing sub-clusters within main clusters and assigning them to groups for phase delay compensation, we ensure the generation of independent narrow beams focused on each receiver simultaneously. To mitigate the grating lobe formation, we incorporate a dual-carrier framework that introduces an effective wavelength for the system. Based on this theoretical model, we examine multi-beam focusing with a systematic arrangement of clusters on a planar ceiling. It follows a phased array within a phased array structure and incorporates a sub-cluster segmentation algorithm. We suggest optimizing cluster excitation based on receiver positions to enhance power efficiency and safety. This involves selecting the optimal clusters from a uniform array by solving a multiobjective non-convex binary optimization problem, aiming to maximize receiver intensity, minimize intensity variations, and reduce side lobes level. Instead of stochastic algorithms, we adopt a sparse relaxation-based weighted sum method that convexifies the binary space with $L_{1}$ norm regularization compensating for convexity. The Transformed problem is solved deterministically via Nelder-Mead simplex without gradients. Simulated results confirm a better multi-beam focusing pattern, effectively balancing three objectives. Our findings pave the way for sustainable indoor optical wireless networks in next-generation communication.