Signalling Load-aware Conditional Handover in 5G Non-Terrestrial Networks

Low Earth orbit (LEO) satellites-based non-terrestrial networks (NTN) are envisioned to complement the fifth-generation (5G) terrestrial networks (TN), enabling global cellular services. However, the high mobility and large coverage of these satellites result in frequent and numerous inter-satellite handovers, leading to signalling storms that degrade the satellite gNodeB services. To address this, we mathematically formulate the handover problem and propose a novel signalling load-aware handover protocol based on conditional handover. We evaluate the effectiveness of the protocol using a customized discrete-event simulator and compare it against a set of baseline conditional handover schemes. Our findings show that the proposed protocol significantly reduces signalling peaks and balances the load more effectively, enhancing the robustness and efficiency of handover in 5G NTN. The simulator is made publicly available.