# What is 5G? Emerging 5G Mobile Services and Network Requirements  
[PERSON]  
1 Department of Information and Communication Engineering, Yeungnam University, Gyeongsan 38541, Korea; [EMAIL_ADDRESS]  
[PERSON]  
2 Department of Electrical, Electronic and Control Engineering, Hankyong National University, Anseong 17579, Korea  
mobile phones, wearable devices, sensors, actuators, vehicles, robots, and so on. Therefore, 5G networks can be regarded as the key infrastructure that innovates societies, as well as ICT industries.  
Research on 5G services and their technical requirements has been performed by the International Telecommunication Union-Radiocommunication Sector (ITU-R), the 3 rd Generation Partnership Project (3 GPP) and the Next Generation Mobile Networks (NGMN) Alliance. In the ITU-R Working Party (WP) 5D, 5G is defined by the name of International Mobile Telecommunications-2020 (IMT-2020),and various 5G services are presented in a vision document [1]. The proposed usage scenarios are grouped into three categories: enhanced mobile broadband (eMBB), massive machine-type communications (mMTC) and ultra-reliable and low-latency communications (URLLC). Peak data rate, area traffic capacity, network energy efficiency, connection density, latency, mobility, spectrum efficiency and user-experienced data rate are selected as key performance indicators (KPIs), which can be regarded as technical requirements. The details are discussed in Section 3.  
The existing approaches for categorizing 5G services are still based on the technical viewpoint of network operators and service providers even though the final goal of 5G services is to maximize the satisfaction of end-users. Therefore, there is a mismatch of viewpoints between the goal and the categorization of 5G services. To overcome this mismatch, the main features of 5G services in terms of end-user experience are proposed in this paper by analyzing the megatrend of future mobile services. As a result of this analysis, 5G services are categorized according to the following five features: immersiveness, intelligence, omnipresence, autonomy and publicness. Each category includes typical 5G services as follows.  
* Immersive 5G services: virtual reality/augmented reality (VR/AR), massive contents streaming
* Intelligent 5G services: user-centric computing, crowded area services
* Omnipresent 5G services: Internet of things
* Autonomous 5G services: smart transportation, drones, robots
* Public 5G services: disaster monitoring, private security/public safety, emergency services  
To provide 5G services effectively, innovative changes in both wireless technologies and core networks are needed. For each service category, the required technologies are examined by analyzing the limitations of current 4G networks for a given service case. Then, qualitative and quantitative description for seven KPIs are provided. Additionally, three different types of requirements for 5G core networks are investigated. Functional, architectural and operational requirements are classified, and critical ones for each service group are suggested.  
For the preparation of the 5G network infrastructure, we first analyze the megatrend of mobile services. Based on this analysis, detailed service scenarios are defined and categorized depending on the characteristics of such services. Finally, the technical requirements for both the wireless communication and the core network sides are examined and proposed in this paper.