On the Deployment of RIS-mounted UAV Networks
Anupam Mondal, Priyadarshi Mukherjee, Sasthi C. Ghosh
TL;DR
This work tackles the deployment of RIS-mounted UAV networks to support both D2D pairs and cellular users in a mmWave OFDMA setting. It introduces a two-stage optimization: first using gradient ascent to position the RIS for maximizing D2D throughput, then using gradient ascent to position the UAV for maximizing CU throughput, followed by a coordinate-search step to obtain a joint RIS-UAV location that maximizes the overall net throughput. The approach accounts for LoS/NLoS path losses and blockage effects, and demonstrates through numerical results that the joint RIS-UAV placement enhances both net throughput and user fairness compared with benchmark strategies that optimize only one user type. The findings underscore the practical value of adaptive RIS-UAV deployments in dynamic or disaster scenarios where reliable, block-free mmWave communication is critical.
Abstract
Reconfigurable intelligent surfaces (RIS) enable smart wireless environments by dynamically controlling signal propagation to enhance communication and localization. Unmanned aerial vehicles (UAVs) can act as flying base stations and thus, improve system performance by avoiding signal blockages. In this paper, we propose a gradient ascent and coordinate search based method to determine the optimal location for a system that consists of a UAV and a RIS, where the UAV serves cellular users (CUs) and the RIS serves device-to-device (D2D) pairs. In particular, by optimizing the net throughput for both the D2D pairs and the CUs, the suggested method establishes the ideal location for the RIS-mounted UAV. We consider both line of sight (LoS) and non-LoS paths for the RIS and UAV to calculate the throughput while accounting for blockages in the system. The numerical results show that the proposed method performs better than the existing approaches in terms of both the net throughput and the user fairness.