Handover Technique in LEO Satellite Networks: A Review

The low Earth orbit (LEO) satellite network, characterized by extensive coverage, is an important component of future non-terrestrial networks (NTNs) architectures and a crucial method to address the explosive growth in user numbers and service requirements. However, due to the rapid movement of LEO satellites, frequent handovers between satellites and mobile users can lead to communication interruptions. Therefore, the increasing number of surveys focused on mobility management in the LEO satellite network is necessary to solve the above problem. Furthermore, handover management which is a constituent aspect of mobility management plays a pivotal role in Space-Air-Ground-Sea Integrated Networks (SAGSINs), particularly in space-based networks consisting of different orbit satellites. This paper introduces an overview of development trends in LEO satellite networks and emphases that handover management is a current problem and necessitates of increasing number of researchers to survey. Then, some existing works about handover management in terrestrial networks are analyzed, including the classification of handovers and decision handover schemes. After that, we present a detailed analysis of handover management technologies in satellite network scenarios including spotbeam handover, satellite handover and inter-satellite link(ISL) handover. Additionally, some enhanced techniques of handover management in satellite-terrestrial integrated networks (STIN) are expounded. Finally, the challenges and the prospects for the development of handover management in satellite networks are pointed out.