Handover-Aware Scheduling for Small- and Large-Scale VLC Networks

This paper proposes handover-aware scheduling solutions for multi-cell small- and large-scale visible-light communication networks, enabling soft handover. For this, we coordinate the transmissions at the access points (APs), serving the users in different time slots based on their locations with respect to the AP coverage areas for an efficient utilization of the resources. For scenarios where coverage in large areas is needed, we additionally propose clustering solutions to decrease the handover rate. Compared with non-coordinated schemes, the proposed soft handover techniques offers improved performance in terms of user achievable throughput and link reliability.

I. Introduction

Visible-light communication (VLC) is considered as a candidate for the sixth generation (6G) wireless networks, to resolve radio-frequency (RF) spectrum congestion, especially in indoor scenarios. The ongoing increase in the number of user devices, the multimedia quality, and the emerging applications (e.g., virtual reality), as well as the spectrum licensing costs, encourage exploring new solutions to complement RF, to keep up with the demand for the network traffic. VLC uses the existing lighting infrastructure for wireless communications. It operates in the unlicensed optical spectrum, is robust against RF electromagnetic interference, and provides inherent physical layer security in the illuminated area. As light does not penetrate through walls, the VLC network is not interfered by transmissions in adjacent rooms, hence, a more efficient and reliable resource utilization can be done, compared to RF networks [1]. In indoor areas, a multi-cell architecture can be used based on multiple light-emitting diode (LED) luminaires, each acting as an access point (AP) that handles the users within its illumination area (i.e., cell). There, users within the coverage areas of one or more APs can be classified as cell-center users (CCUs) or cell-edge users (CEUs), respectively [2]. To mitigate multi-user interference, efficient management of the resources using multiple access (MA) techniques should be used [3].