Location-based Handover Triggering for Low-Earth Orbit Satellite Networks

Broadband low Earth orbit (LEO) satellite constellations are a reality. The integration of satellite and terrestrial systems for mobile communications is taking-off with the development of non-terrestrial networks (NTN) and the ongoing deployment of private constellations. Due to the highly mobile nature of LEO satellites, one of the critical research areas is the design of the mobility mechanisms to ensure robust service continuity for the end user. Recent studies in the domain of the Earth-moving cells have shown that solely measurement-based handover (HO) triggering events cannot guarantee a low number of radio link failures without an increase in signalling and measurement reporting. In this work, we present a new HO triggering event that exploits the deterministic movement of LEO satellites and uses the distance between the user's location and the centre of the moving cells on the ground. The performance of the proposed solution is evaluated with system-level simulations and compared against the measurement-based baseline HO and Rel-16 Conditional HO (CHO). It is found that the location-based HO triggering event completely eliminates the HO failures as well as the unnecessary HO. As a result, the location-based HO triggering event extends the average time-of-stay from 2 s to 5 s where the theoretical time-of-stay is 6 s.