RIS-Assisted Proactive Handover for Reliable mmWave Wireless Networks
Authors: Alaa Adnan, Mohammad Al-Quraan, Ahmed Zoha, M. Majid Butt, Sami Muhaidat, Muhammad Ali Imran, Marco Di Renzo, Lina Mohjazi
Organizations: James Watt School of Engineering, University of Glasgow, Glasgow, G12 8QQ, UK · Nokia Standards, USA · KU 6G Research Center, Department of Computer and Communication Engineering, Khalifa University, Abu Dhabi 127788, UAE · Department of Systems and Computer Engineering, Carleton University, Ottawa, ON K1S 5B6, Canada · Universit´e Paris-Saclay, CNRS, CentraleSup´elec, Laboratoire des Signaux et Syst`emes, 3 Rue Joliot-Curie, 91192 Gif-sur-Yvette, France · King’s College London, Centre for Telecommunications Research Department of Engineering, WC2R 2LS London, UK
Millimeter-wave (mmWave) networks are highly susceptible to line-of-sight (LoS) blockages. Vision-aided wireless communications (VAWC) enable proactive handovers (PHO) to mitigate such blockages; however, PHO becomes challenging when no nearby base station (BS) is available. In such cases, reconfigurable intelligent surfaces (RIS) can be used to restore connectivity. To ensure timely PHO, the RIS configuration time must be taken into account, as the large number of RIS elements can limit responsiveness in time-sensitive scenarios. This work proposes a novel RIS-assisted PHO approach that optimizes the number of allocated RIS elements to balance signal processing complexity and link quality under handover timing constraints, making the RIS-assisted link more energy-efficient. An optimization problem based on particle swarm optimization (PSO) is formulated to determine the optimal end-to-end RIS link setup that runs offline to bypass latency constraints. Results show that reducing the number of RIS elements by 12% leads to a 10% decrease in dissipated energy without compromising the signal-to-noise ratio (SNR). Moreover, the RIS-assisted link achieves a 15--30 dB improvement in blocked regions while maintaining accurate PHO timing.