Optimisation de la liaison montante d’un système de communication multi-utilisateur assisté par des surfaces intelligentes vers une plateforme aérienne à haute altitude

Abstract

This thesis focuses on optimizing uplink communications in an integrated high-altitude platform (HAPS)–intelligent surface (RIS) telecommunications system, where users share HAPS resources and the reflective elements of an intelligent RIS surface. After accurately modelling the user–HAPS and RIS–HAPS channels according to a Nakagami-m distribution, the problem is formulated as a joint optimization of transmission powers and RIS phases to maximize the total sum throughput of the system. This optimization is constrained by minimum quality-of-service (QoS) requirements for each user. Various optimization algorithms are explored, including a random method (Random) serving as a baseline reference, which is developed into a partially random baseline method (Baseline), quantifying a few parameters (such as RIS power and phase shift), metaheuristic algorithms such as the Whale Optimization Algorithm (WOA) and Particle Swarm Optimization (PSO), and finally a proposed iterative optimization approach, i.e., Alternating Optimization (AO). Through extensive simulations, we compare these methods in terms of sum data rate, and under the impact of several system parameters (e.g., number of antennas, maximum power, etc.), highlighting the trade-offs between performance and complexity.

Date	29 Aug 2025
Original language	French
Awarding Institution	École de technologie supérieure
Supervisor	Waël Jaafar (Supervisor) & Georges Kaddoum (Co-supervisor)