Two-Way Selection Handover Algorithm for Load Balancing in Hybrid VLC-RF Networks

Heterogeneous network (HetNet) composed of visible light communication (VLC) and radio frequency (RF) is considered as a promising solution for future high-speed indoor wireless communication. On the one hand, due to the small coverage area of VLC and the co-channel interference caused by dense deployment of VLC access points (APs), mobile user equipments (UEs) may experience frequent handovers and are more likely to transfer to RF AP with larger coverage. On the other hand, load balancing schemes can be induced to solve the problem of RF overload with the cost of extra handover overhead. This paper develops a two-way selection handover algorithm considering load balancing to improve system overall performance. Our algorithm first selects the appropriate target AP based on the hybrid technique of the fuzzy analytic hierarchy process (FAHP) and the technique for order preferences by similarity to ideal solution (TOPSIS) for every UE who need to handover. And then we find the set of higher priority UEs for RF AP. Simulation results show that the proposed algorithm can not only significantly improve average user throughput, user fairness, but also evenly distribute the traffic load.