Color Planning and Intercell Interference Coordination for Multicolor Visible Light Communication Networks

We address the intercell interference coordination for the indoor attocell multicolor visible light communication (VLC) network under lighting constraints. In the multicolor VLC system, soft frequency reuse-based interference coordination is adopted, which adjusts the signal deviations transmitted on cell-edge color and cell-center color. A static scheduler is proposed to increase the signal-to-interference-plus-noise ratio (SINR) for the cell-edge region, given that the SINR for the cell-center region is larger than a certain threshold. To adapt to the interference intensity that varies with the density of base stations, we propose a dynamic scheduler for the intercell interference coordination. The dynamic scheduler comprises of two separate parts: the distributed part that adjusts the power allocation and asks to restrict color usages in neighboring attocells, and the centralized part that resolves the color conflicts and allocates the color resources in the network. Two solution approaches are proposed for the centralized part, one based on the linear programming relaxation of the integer programming, and the other based on the greedy color allocation. Simulation results show that the dynamic scheduler can improve the cell-edge user's throughput with acceptable penalty to the overall throughput.