Mobility Management: a Satellite-Aerial-Ground Integrated Network Perspective

The space-air-ground integrated network (SAGIN) represents a major breakthrough in the advancement of Beyond 5G/6G, seamlessly combining terrestrial network (TN) and nonterrestrial networks (NTN) into a unified multi-layered system by creating a more cohesive and efficient communication infrastructure. However, the high mobility of NTN platforms creates significant challenges in managing user transitions across these interconnected layers. This article offers a concise overview of the unique demands of mobility management (MM) in SAGIN and the architectural developments required to meet the needs of various service categories, including enhanced mobile broadband (eMBB), massive machine type Communications (mMTC), and ultra reliable low latency Communications (URLLC). Additionally, the article details specific strategies for vertical handovers in SAGIN, as described in the literature, with a focus on the roles of software defined network (SDN), network function virtualization (NFV), and network slicing (NS).