alized, which can support physical layer cooperation across various trans- mission/reception nodes. In case of non-ideal fronthaul, the DU(s) can be deployed in a dis- tributed manner. Therefore, a C-RAN architecture based on NGFI interface supports not only the centralized DU deployments, but also enables distributed DU deployments. Mobile networks have traditionally been optimized for voice and data services. However, in 5G era, they have to serve a variety of devices with different characteristics and service/per- formance requirements. As mentioned earlier, some of the most common use cases for 5G include mobile broadband, massive IoT, and mission-critical IoT, and they all require Central office Central office Himal (((p))) IIIIIII Distributed unit Centralized unit Centralized unit MEC server (DU), Ideal fronthaul (ip)) ((q)) Central office ((q))) Centralized unit Non-ideal fronthaul ((p)) ((ip)) (((2))) Distributed unit (DU) Distributed unit (DU) Remote site Remote site Distributed unit (DU) Remote site Figure 11 CU/DU-based C-RAN architecture 23 -26]. xlvi Introduction and Background different types of features and networks in terms of mobility, charging, security, policy con- trol, latency, reliability, etc. For instance, a massive IoT service that connects stationary sensors measuring temperature, humidity, precipitation, etc. to mobile networks does not require features such as handover or location update, which have been critical in serving voice services. A mission-critical IoT service such as autonomous driving or remote-con- trolled robots requires a substantially low end-to-end latency in the order of a fraction of millisecond, whereas some massive MTC services are delay-tolerant. The objective of network slicing is to transform the network from using a rather static one- network-fits-all approach to a dynamic model where multiple logical networks can be cre- ated on top of the same physical infrastructure to fulfill the diverse needs of different use cases. Network slicing is a concept that enable