, mobile applications, the rapid increase in subscriber size, and cellular communication bandwidth. The trend of cellular data growth will continue to accelerate as technology and application availabilities further improve. Indeed, in 2009, mobile data traffic exceeded mobile voice traffic for the first time [2, 3], starting the new paradigm of mobile networks. The dominant usage of mobile network has shifted from low bandwidth voice and messaging traffic Network Function Virtualization: Concepts and Applicability in 5G Networks, First Edition. Ying Zhang. © 2018 John Wiley & Sons, Inc. Published 2018 by John Wiley & Sons, Inc. 1 Introduction to a diverse type of data traffic, ranging from web browsing, video streaming, and even online gaming. Existing report [4] has shown that the mobile data traffic is increasing at a rate of 60% per year. By the end of 2016, mobile traffic has surpassed the traffic generated in the wireline network [5, 6]. It is predicted that by the year of 2018, the yearly IP traffic globally will be 64 times of that in 2005. The demand on mobile network infrastructure will be further increased as the market of Internet of things (IoT) grows. IoT devices and their applications that function without direct human intervention are rapidly becoming an integral part of our lives. IoT devices and applications have wide use cases in a variety of areas, including telehealth, shipping and logistics, utility and environmental monitoring, industrial automation, and asset tracking. It is predicted to be 25 billion devices - including fixed/mobile personal devices and IoT devices - connected to IP networks [5] by the year of 2020 with a seven trillion dollar market value. The Machine-to-Machine (M2M) communications will generate 80% more data than the human directly generated data in the year of 2018. The prosperity of IoT industry requires great support of the wide area wireless communication infrastructure, in particular, the cellular data networks. To cope with the explosive cellular data volume growt