Accelerating Handover in Mobile Satellite Network

TL;DR

The paper tackles the persistent handover latency in mobile satellite networks with LEO constellations by introducing a flowchart that decouples core-network signaling from the RAN, leveraging the predictability of satellite trajectories and spatial distribution. It proposes a synchronized UPF-based algorithm using two prediction points and a fast, partitioned prediction approach to minimize core-RAN interactions and computational burden. The authors implement a prototype with Open5GS and UERANSIM driven by Starlink and Kuiper traces, and demonstrate about a 10x reduction in handover latency and notable improvements in user-plane performance compared with 3GPP NTN baselines. The work highlights practical gains for 5G/6G NTN deployments while outlining limitations and future work on access-satellite strategies and trajectory-prediction accuracy, with broad implications for scalable, low-latency satellite communications.

Abstract

The construction of Low Earth Orbit (LEO) satellite constellations has recently spurred tremendous attention from academia and industry. 5G and 6G standards have specified LEO satellite network as a key component of 5G and 6G networks. However, ground terminals experience frequent, high-latency handover incurred by satellites' fast travelling speed, which deteriorates the performance of latency-sensitive applications. To address this challenge, we propose a novel handover flowchart for mobile satellite networks, which can considerably reduce the handover latency. The innovation behind this scheme is to mitigate the interaction between the access and core networks that occupy the majority of time overhead by leveraging the predictable travelling trajectory and spatial distribution inherent in mobile satellite networks. Specifically, we design a fine-grained synchronized algorithm to address the synchronization problem due to the lack of control signalling delivery between the access and core networks. Moreover, we minimize the computational complexity of the core network using information such as the satellite access strategy and unique spatial distribution, which is caused by frequent prediction operations. We have built a prototype for a mobile satellite network using modified Open5GS and UERANSIM, which is driven by actual LEO satellite constellations such as Starlink and Kuiper. We have conducted extensive experiments, and the results demonstrate that our proposed handover scheme can considerably reduce the handover latency compared to the 3GPP Non-terrestrial Networks (NTN) and two other existing handover schemes.

Figures (11)

• Figure 1: Two different operating modes of mobile satellite network in (a) transparent mode and (b) regenerative mode.
• Figure 2: Illustration of handover signaling transmission, e.g., London to Shanghai.
• Figure 3: Transmission latency of different parts in handover.
• Figure 4: Comparison of standard and our proposed Xn-based handover procedure in mobile satellite network.
• Figure 5: Structure and Operation of UE-satellite relationship.