Joint LED Selection and Precoding Optimization for Multiple-User Multiple-Cell VLC Systems

This paper proposes a hybrid dimming scheme based on joint LED selection and precoding design (TASP-HD) for multiple-user (MU) multiple-cell (MC) visible light communications (VLC) systems. In TASP-HD, both the of each cell can be dynamically adjusted to reduce intra- inter-cell interferences while satisfying illumination constraints. First, MU-MC-VLC system model is established, then sum-rate maximization problem under level uniformity constraints formulated. this studied problem, indices activated LEDs matrices are optimized, which result in complex non-convex mixed integer problem. To solve original separated into two subproblems. The first subproblem, maximizes users via optimizing with given matrix, solved by penalty method. With optimized second subproblem focuses matrix Lagrangian dual Finally, these subproblems iteratively obtain convergent solution. Simulation results verify that typical indoor scenario 70%, mean bandwidth efficiency TASP-HD 4.8 bit/s/Hz 7.13 greater than AD DD, respectively.