IRS-Aided Handover Technique in Indoor VLC Blockage-Affected Systems

Handover management in indoor visible light communication systems can be enhanced by the use of intelligent reflective surfaces (IRS). In general, the use of IRSs avoids blockage conditions, since they allow to exploit non-direct connectivity links, guaranteeing a seamless connectivity to the end user. On the other hand, in realistic scenarios, blockages due to shadowing and obstacles may occur, affecting the condition of line-of-sight from a light emitting diode (LED) to a receiver. Therefore, it is relevant to provide solutions for redirecting the optical signal from the blocked LED to the end user. In this paper, we present an IRS-aided handover technique that initiates a hard or soft handover triggered by the blockage probability affecting the LED luminaries. The proposed approach has been assessed in terms of achievable data rate and number of handovers, for different user speed and random mobility patterns, as well as number of LEDs deployed in a given indoor scenario. Simulation results reveal the benefit of using IRSs in avoiding connectivity holes, as proactively initiating a hard/soft handover toward a neighboring LED access point or an IRS, based on any blockages affecting direct and no line-of-sight links. Comparing the performance achieved without IRS and for multiple IRSs, we show that the effect of multiple IRSs is affected by geometrical parameters of the LED luminaries.