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Handover Management through Reconfigurable Intelligent Surfaces for VLC under Blockage Conditions

Kapila W. S. Palitharathna, Anna Maria Vegni, Panagiotis D. Diamantoulakis, Himal A. Suraweera, Ioannis Krikidis

TL;DR

This paper tackles seamless connectivity in indoor VLC under blockage by introducing a reconfigurable intelligent surface (RIS)-assisted proactive handover framework. It leverages a mirror-based RIS to redirect optical links when LoS is blocked, enabling hard and soft handovers, and employs a lightweight ANN to optimally assign RIS elements to access points based on blockage patterns and user position. The approach is evaluated in a simulated 5 m × 5 m × 3 m room, showing data-rate gains of up to 60% (soft handover up to 80%), reduced handover latency (1–4.5 μs), and fewer connectivity holes. These results highlight the practical impact of RISs in enhancing robustness and efficiency of VLC handovers in blockage-prone environments.

Abstract

In this paper, we consider an indoor visible light communication (VLC) system with multiple "white" light emitting diodes serving to form overlapping wireless communication cells. In order to maintain seamless connectivity to mobile users, a handover procedure should be implemented. In particular, practical conditions such as blockages due to obstacles inside the room environment and the mobility of users can affect direct VLC connectivity. The use of reconfigurable intelligent surfaces (RISs) in optical wireless systems allows to exploit non-direct connectivity links, thus providing efficient communication links. In this paper, we present a proactive handover mechanism that exploits the presence of a RIS, in order to redirect the communication links in case of blockages. The proposed approach has been implemented both in hard and soft modes and assessed in terms of achievable data rate and handover latency for a user walking in a given reference room at different user speeds and blockage conditions. Our presented results and comparisons with conventional handover methods (i.e., without RIS) are helpful in showing the superiority of the presented algorithm.

Handover Management through Reconfigurable Intelligent Surfaces for VLC under Blockage Conditions

TL;DR

This paper tackles seamless connectivity in indoor VLC under blockage by introducing a reconfigurable intelligent surface (RIS)-assisted proactive handover framework. It leverages a mirror-based RIS to redirect optical links when LoS is blocked, enabling hard and soft handovers, and employs a lightweight ANN to optimally assign RIS elements to access points based on blockage patterns and user position. The approach is evaluated in a simulated 5 m × 5 m × 3 m room, showing data-rate gains of up to 60% (soft handover up to 80%), reduced handover latency (1–4.5 μs), and fewer connectivity holes. These results highlight the practical impact of RISs in enhancing robustness and efficiency of VLC handovers in blockage-prone environments.

Abstract

In this paper, we consider an indoor visible light communication (VLC) system with multiple "white" light emitting diodes serving to form overlapping wireless communication cells. In order to maintain seamless connectivity to mobile users, a handover procedure should be implemented. In particular, practical conditions such as blockages due to obstacles inside the room environment and the mobility of users can affect direct VLC connectivity. The use of reconfigurable intelligent surfaces (RISs) in optical wireless systems allows to exploit non-direct connectivity links, thus providing efficient communication links. In this paper, we present a proactive handover mechanism that exploits the presence of a RIS, in order to redirect the communication links in case of blockages. The proposed approach has been implemented both in hard and soft modes and assessed in terms of achievable data rate and handover latency for a user walking in a given reference room at different user speeds and blockage conditions. Our presented results and comparisons with conventional handover methods (i.e., without RIS) are helpful in showing the superiority of the presented algorithm.
Paper Structure (6 sections, 4 equations, 4 figures, 1 algorithm)

This paper contains 6 sections, 4 equations, 4 figures, 1 algorithm.

Table of Contents

  1. Introduction
  2. System model
  3. Proactive Handover Mechanism
  4. ANN-based RIS Assignment
  5. Numerical Results
  6. Conclusions

Figures (4)

  • Figure 1: Schematic of (a) hard and (b) soft handovers, for a mobile user in an overlapping lighting cells indoor scenario with the help of RIS mounted on a wall in the reference scenario.
  • Figure 2: Average handover data rate vs. number of APs.
  • Figure 3: Average handover latency vs. number of APs.
  • Figure : : Proactive Handover Using RIS