Stochastic Geometry Analysis of User Mobility in RF/VLC Hybrid Networks

Abstract

The integration of visible light communication (VLC) with existing radio frequency (RF) networks has emerged as a new network architecture to meet the rapidly growing traffic demand. The resulting RF/VLC hybrid network structures offer capacity-per-area improvements due to the use of two technologies operating at different frequency bands and the relatively higher base station (BS) density. However, the reduced BS coverage footprints and the heterogeneous BS types result in challenges for user mobility such as frequent handovers and the need for suitable BS association policies. To help addressing these challenges, in this paper, we conduct a user mobility analysis for RF/VLC hybrid networks by deriving the user-to-BS association probabilities and handover rates. The analysis makes use of stochastic geometry and modeling BSs’ locations via a Poisson point process (PPP). Since PPP modeling has not yet been well established for hybrid RF/VLC networks, we support the applicability of our approach by comparing the user mobility performance to those obtained for an actual deployment, a Matérn hard-core point process (MHCPP) based deployment, and a deterministic square lattice deployment of VLC luminaries. Furthermore, since the handover rates directly depend on the association policies, we consider two popular association policies. Our numerical results show that the PPP, the MHCPP, the square lattice, and the actual deployments have comparable performance in terms of handover rates regardless of the association policy, and they highlight the tradeoff between balancing network load and handover rates achieved by the association policies.