Towards Location Management in SDN-based MCN

One of the key functionalities in EPC (Evolved packet Core) is Mobility Management (MM), which provides procedures for service continuity as the mobile devices (UE) move across the network. In a quest for more flexibility of MM, recent studies suggested to map MM procedures to SDN applications in an SDN controller. So far, these proposals investigated and showed how path switching during handover, one of the procedures of MM, is achieved in such an SDN-based Mobile Core Network (MCN). However, Location Management (LM) procedures, such as paging, are equally important. In this paper, we address this gap. We notably design and implement SDN-based UE state management and paging procedure for MCN. Our design only uses the data from the SDN controller, such as UE connectivity and flow information, and defines a new set of UE states: deregistered, idle, and active. We introduce new, dynamically configurable UE inactivity timers that regulate the transitions among these states. With this, we implement a purely SDN-based paging procedure capable of bringing a UE into a connected state on request, e.g. to deliver the downlink traffic. The experiments with our implementation on Floodlight SDN controller under different network loads and configuration settings for UE inactivity timers in Mininet demonstrate the practical feasibility of an SDN-based LM. Further, we show how different UE inactivity timer values can flexibly regulate the amount of paging. All in all, our results suggest that, leveraging the programmability provided by SDN, operators can flexibly install and use LM SDN apps with different settings to tailor the amount of paging according to the specific UE or user application activity patterns and its needs.