**1.2 5G system architecture**

Today we see the evolution of Industry 4.0 manifested in smart factories, where collaborative robots are instantly connected. The entertainment industry advances dramatically with AR/VR technologies. People are using Zero Search with intelligent personal digital assistants. The Intelligent Transportation Systems (ITS) require all cars connected via C-V2X protocol. The Industrial Internet of Things (IIoT) is used in smart cities and smart agriculture. This is the business ecosystem of 5G systems [6]. 5G systems enable people for living in an intelligently connected world. The 5G system architecture is illustrated in **Figure 1**. At the highest level, the 5G system consists of 5G NR RAN (gNB), 5G Core Network (5GCN)/EPC and different kinds of UEs for three kinds of service including Enhanced Mobile Broadband (eMBB), Ultra-reliable and Low-latency Communications (uRLLC), and Massive Machine Type Communications (mMTC) in a business ecosystem [7].
