On Optimizing Network Function Placement for Multicast Group Call Service Provision in LTE IOPS Networks

The adoption of commercial wireless technologies such as 4G/5G in public safety networks allows for new broadband services that could not be offered in this type of networks. Nevertheless, public safety networks are mission-critical systems that require the introduction of specific services in commercial wireless networks before this adoption. For instance, public safety networks require push-to-talk group communications or the possibility of operating in isolated mode, named by 3GPP the Isolated E-UTRAN Operation for Public Safety (IOPS). These requirements pose specific challenges that must be addressed, such as the placement of a local Evolved Packet Core (EPC) when a set of evolved Node B (eNB) must work in IOPS mode. In this paper, we analyze the implications of push-to-talk group communications and multicast in the local EPC placement problem for IOPS networks and propose an optimization algorithm that finds the best eNB where the local EPC should be co-located. Given the complexity of the problem, we also propose a heuristic algorithm to determine the optimal placement of the local EPC. Simulation results show the ability of our approach to adapt to different types of traffic with heterogeneous spatial distributions.