As the number of mobile users grows rapidly, wireless access technologies are evolving to provide high data rates to mobile users and to support emerging applications involving both human and machine-type communications. In this context, 5G is considered as a solution to provide wireless users with high coverage and increased network capacity, by enabling the integration of heterogeneous networks, that may have different wireless access technologies, coverage area sizes and topologies. Within such a setting, a user or a device may find more than one candidate air interfaces to connect or to perform a handover; this further highlights the need for optimum connectivity and seamless mobility in heterogeneous networks to also address the requirements of the emerging 5G vertical use cases in different sectors such as autonomic cars, industrial robotics, Internet of Things etc. In this article, a concise overview of the trends in mobility management will be provided considering the emerging 5G architectures and service types (eMBB, mMTC, URLLC). Specific approaches of vertical handover in 5G are described, considering the novel architectural changes imposed by Software defined Networking (SDN), Network Function Virtualization (NFV) and Multi-Access Edge Computing (MEC). In addition, the paper will address mobility management evolutionary steps in signaling based on the novel architectural elements imposed by SDN, NFV and MEC, considering the requirements of different vertical use cases that will lead to the required throughput, latency, and scalability. (C) 2020 Elsevier B.V. All rights reserved.
