Dynamic IMS Reconfiguration using Session Migration for Power Saving

Legacy telecommunication services have been tending to shift to All-IP networks from closed and circuit switched networks by the deployment of high bandwidth and stable mobile broadband networks such as Long Term Evolution (LTE). The shift to an All-IP network leads to the integration of telecommunication services and internet services, which are called Over-The-Top (OTT) services. The trend towards increasing and unpredictable traffic makes it important for the IP Multimedia Subsystem (IMS), which is a call control system running over the All-IP network, to be flexible and reliable. With that goal, the authors have proposed an IMS reconfiguration mechanism using call session state migration, which allows the IMS to distribute live call sessions as required by the failure of IMS servers and the quantity of calls in progress. Furthermore, in this paper we propose a model to determine the configuration of the IMS dynamically from the perspective of electrical power consumption and performance. A formula based on the model calculates which IMS servers should be active and which call sessions should move to which IMS servers to reduce the overall power consumption, using linear programming. Moreover, this paper implements the proposal and shows its results. Keywords-IMS; SIP; Session Migration; Power Saving; Linear Programming; Optimization; CPLEX