Performance Evaluation of the Conditional Handover for 5G Mobility in LEO-based Non-Terrestrial Networks

The development of non-terrestrial networks (NTN) aims to satisfy the requirements of ubiquitous and seamless coverage for 5G and 6G services. Nonetheless, Low Earth orbit (LEO) satellites introduce challenging mobility conditions to the conventional radio resource management algorithms. Current research show that the baseline 5G UE-assisted network-controlled handover (HO) mechanism, designed for terrestrial networks, may not meet the exigency to ensure a continuous and satisfactory service in NTN. The conditional handover (CHO), specified by 3GPP in Rel-16, was designed to enhance mobility robustness by making preparation decisions earlier. In this work, we conduct system-level simulations to evaluate the 5G mobility performance of the CHO in a LEO-based NTN context. The simulation results show that the CHO brings a reduction of 99% of the handover failure rate in comparison with the baseline HO but leads to an increase of the unnecessary HO rate by 99%, which leads to an increase of the signaling and measurement reporting. Finally, future research directions are identified to address the increase of the signaling overhead by exploiting the predictability of the satellites movement.