Design, Implementation and Validation of Beam-Hopping Protocols for 5G NR Non-Terrestrial Networks

To enhance connectivity and resilience, 5G infrastructure is increasingly expanding into the sky. Non-Terrestrial Networks (NTNs), comprising Unmanned Aerial Vehicles (UAVs), High Altitude Platforms (HAPs), and satellites, are emerging as a robust complement to terrestrial systems. Driven by academic and industrial efforts, these networks are transitioning from concepts to real-world deployments. However, NTNs pose unique challenges that require a redefinition of the 5G protocol stack. Long distances introduce significant propagation delays, while high attenuation reduces signal quality, making reliable communication difficult. Using MIMO and beamforming, satellites can steer narrow, high-gain beams toward specific areas, while Spatial Division Multiple Access (SDMA) enables multiple beams to operate without interference. Since each beam covers only a small geographical region on Earth, the beams must be dynamically repositioned over time to cover the entire satellite footprint - a technique known as Beam Hopping (BH). This thesis develops and evaluates heuristic policies for single-beam BH in NTNs, using the full-stack and modular ns-3 simulator. A key contribution of this work is the extension of the ns3-NTN module to support BH, enabling system-level evaluation of BH strategies. The work starts by implementing a basic BH framework, including the creation of a dedicated Beam Hopping Manager class, modifications to the existing 5G scheduler, and a Service Access Point (SAP) for coordination. During this process, several issues related to propagation delay in the scheduler were identified and resolved. A series of simple heuristic policies are developed - including Round-Robin, waiting-time-based and buffer-size-based approaches - and then tested via simulations under realistic traffic, channel, and protocol conditions. Overall, the obtained results reveal clear trade-offs between efficiency, fairness, and delay, underscoring the complexity of BH design in NTNs.