Non-Preemptive Conditional Handover Strategy for High-Reliability LEO Satellite Networks

Abstract

Mobility management in Low-Earth Orbit (LEO) satellite networks faces severe challenges due to high-speed satellite dynamics, where conventional signal-based handover mechanisms often trigger excessive redundant handovers and signaling storms. Although the 3GPP Conditional Handover (CHO) framework improves reliability, existing optimization strategies often overlook multi-user resource contention. To fill this gap, this paper proposes a Non-Preemptive Conditional Handover (NPCHO) strategy designed for resource-constrained LEO constellations. Guided by a delayed-handover philosophy, NPCHO maintains the current link stability and defers handover execution until the serving satellite's elevation angle drops below a critical threshold. It utilizes deterministic satellite trajectories and dynamic beam availability to dictate handover decisions, suppressing network overhead while securing reliability. High-fidelity simulations incorporating dynamic beam constraints demonstrate that NPCHO drastically cuts the average handover count by 52.09% compared to the preemptive policy. Crucially, with 21 beams allocated per satellite, NPCHO achieves zero handover failures and more than doubles the average link duration. These results establish NPCHO as a highly reliable, efficient, and scalable mobility management solution for next-generation Non-Terrestrial Networks (NTN).