Dynamic load balancing with handover in hybrid Li-Fi and Wi-Fi networks

In this paper, a hybrid network combining visible light communication (VLC) with a radio frequency (RF) wireless local area network (WLAN) is considered. In indoor scenarios, a light fidelity (Li-Fi) access point (AP) can provide very high throughput and satisfy any illumination demands while wireless fidelity (Wi-Fi) offers basic coverage. Such a hybrid network with both fixed and mobile users has the problem of variable user locations, and thus large fluctuations in spatially distributed traffic demand. Generally, a handover occurs in such a method when a user is allocated by the central controller unit to a different AP which is better placed to serve the user. In order to be representative of real deployments, this paper studies the problem of load balancing of a dynamic system where we consider the signalling overhead for handover. We propose a scheme for dynamic allocation of resources to users, where the utility function takes into account both throughput and fairness. The simulation results show that there is a trade off between the aggregate throughput and user fairness when handover overhead is considered. The proposed dynamic scheme always outperforms the considered benchmarks in terms of fairness and can achieve better aggregate throughput in the case of low user density.