Handover Probability of Hybrid LiFi/RF-Based Networks with Randomly-Oriented Devices

This paper focuses on the handover probability as a result of the random rotation of a user equipment (UE) in hybrid light-fidelity (LiFi) and radio frequency (RF) networks. A received signal strength indicator (RSSI)-based handover algorithm is considered in this study. Using RSSI as the user association rule does not guarantee that the randomly-oriented UE is always associated with the nearest access point (AP). In some cases, depending on the orientation of the UE, the received signal powers from the LiFi APs are very weak and unreliable. Therefore, a vertical handover from the LiFi AP to the RF AP is required to maintain the user quality of service. Hence, it is essential to study the handover probability due to the change of orientation. A theoretical analysis of the handover probability based on a Markov chain model is provided. The analytical results are confirmed by the Monte Carlo simulation. The effects of some parameters, such as the threshold, hysteresis level and the trade-off between the frequency and the delay of handover are presented in this paper.