Abstract
Network and network functions virtualization (NFV) promise a number of attractive benefits and thus have driven mobile network operators to transform their previously static networks to more dynamic and software-defined networks. In this article, we share a mobile network operator's view based on implementation and deployment experiences in the wild during the past few years towards a software-defined 5G core network. More specifically, we present a practical point of view from mobile network operators and elaborate on why some of the virtualization benefits such as total cost of ownership (TCO) reduction are not easily realized as initially intended. Then, we describe 5G visions, services, and their requirements commonly agreed across mobile operators globally. Given the requirements, we then introduce desirable characteristics of 5G mobile core network and its key enabling technologies.