SigHitching: Efficient Non-Broadcast Paging in Direct-to-Cell LEO Satellite Networks

Direct-to-cell Low Earth Orbit (LEO) satellite networks have emerged as a transformative solution for global 4G/5G connectivity. However, the unique characteristics of LEO systems, including rapid satellite mobility, long space-to-ground propagation delays, and extensive coverage, challenge conventional paging mechanisms, causing unacceptable latency and signaling overhead. This paper introduces SigHitching, a standards-compliant, non-broadcast paging mechanism that leverages device-to-device (D2D) to relay paging signaling to reach idle User Equipments (UEs) efficiently. Additionally, SigHitching incorporates offline service area configuration and a bitmap-based base station selection algorithm to reduce the paging procedure completion time. We implement a prototype of SigHitching using Open5GS and UERANSIM, and emulate LEO constellations based on real satellite data. Experimental results show that SigHitching achieves a 45.23% and 29.81% improvement in paging latency compared to 5G NTN and satellite-native solutions such as SpaceCore and MOSAIC. These results highlight SigHitching’s potential to improve paging efficiency and enable sustainable, scalable global connectivity.