HANDOVER SCHEMES IN SATELLITE NETWORKS: STATE-OF-THE-ART AND FUTURE RESEARCH DIRECTIONS

Low Earth Orbit (LEO) satellites will work as an important component in future data communication networks. LEO satellites provide low end-to-end delays and efficient frequency spectrum utilization, making them suitable for personal communication. However, due to high satellite speed, ongoing communication using LEO constellations experiences frequent handover. In this article we provide an up-to-date, comprehensive literature survey on proposed handover schemes for LEO satellite systems. We also present a detailed classification of handover schemes based on a common framework. We first classify the schemes into link-layer and network-layer handover schemes. Link-layer handover schemes are further classified into three categories: spotbeam handover schemes, satellite handover schemes, and ISL handover schemes. Spotbeam handover schemes are categorized based on channel capacity, handover guarantee, and handover prioritization techniques. Network-layer handover schemes are also classified depending on connection transfer strategies. Finally, we compare the handover schemes using different quality of service (QoS) criteria.