ffic distribution across various access links, and enables the provision of new high-data-rate services. The new RAN architecture is also required to support operator-controlled side-link (D2D and V2X) operation in both in-coverage and out-of-coverage scenarios. The UE can connect to the network directly (direct network connection), connect via another UE acting as a relay (indirect network connection), or connect using both types of connections. These user terminals can be anything from a wearable, monitoring human biometrics, to non-wear- able devices that communicate in a personal area network such as a set of home appli- ances (e.g., smart thermostat and entry key) or the electronics in an office environment (e.g., smart printers). The relay UE can access the network using 3GPP or non-3GPP access (e.g., WLAN access, fixed broadband access). 3GPP and non-3GPP radio tech- nologies and fixed broadband technologies over licensed bands or unlicensed bands can be supported as connectivity options between the remote UE and the relay UE. 4. Separation of control- and user-plane functions is a key step toward enabling SDN- controlled networks. This feature is also an enabler for the network slicing and the NFV Ixiv Introduction and Background infrastructure. The next-generation network is built on NFV and software-defined net- working to reduce the total cost of ownership and to improve operational efficiency, energy efficiency, and simplicity and flexibility of the network for offering new services. 5. Support of network sharing and network slicing is yet another important requirement. Network slicing allows the operators to provide several customized network services over the same physical network. For example, there can be different requirements on each network slice functionality (e.g., priority, charging, policy control, security, and mobility), differences in performance requirements (e.g., latency, mobility, availability, reliability, and data rates), or each network slice can serve only specific users (e.g., m