Load Balancing for Hybrid LiFi and WiFi Networks: To Tackle User Mobility and Light-Path Blockage

Combining the high-speed data transmission of light fidelity (LiFi) and the ubiquitous coverage of wireless fidelity (WiFi), hybrid LiFi and WiFi networks (HLWNets) are recently proposed to improve the system capacity of indoor wireless communications. Meanwhile, load balancing becomes a challenging issue due to a complete overlap between the coverage areas of LiFi and WiFi. User mobility and light-path blockages further complicate the process of load balancing, since the decision for a horizontal or a vertical handover in a mobile environment with ultra-small cells is non-trivial. These issues are managed separately in most conventional methods, which might cause frequent handovers and compromise throughput. A few studies address these issues jointly for selecting access points at each time instant but require excessive computational complexity. In this paper, a joint optimisation problem is formulated to determine a network-level selection for each user over a period of time. A novel algorithm based on fuzzy logic is also proposed to reduce the computational complexity that is required to solve the optimisation problem. Results show that compared to the conventional method, the proposed approach can improve system throughput by up to 68%, while achieving very low computational complexity.