n area. The NG-RAN and the 5GC can manage service requests for a slice that may or may not be available in a given area. Admission or rejection of access to a slice may depend on certain factors such as sup- port for the slice, availability of resources, and support of the requested service by other slices. In the case where a UE is simultaneously associated with multiple slices, only one signaling connection is maintained. For intra-frequency cell reselection, the UE always tries to camp on the best cell, whereas for inter-frequency cell reselection, dedicated priorities can be used to control the frequency on which the UE camps. Slice awareness in NG-RAN is introduced at PDU session level by indicating the S-NSSAI corresponding to the PDU session in all signaling containing PDU session resource information. 5GC validates whether the UE is authorized to access a certain network slice. The NG-RAN is informed about all network slices for which resources are being requested during the initial context setup [3,15]. Resource isolation enables specialized customization of network slices and prevents adverse effects of one slice on other slices. Hardware/software resource isolation is up to implementa- tion; nevertheless, RRM procedures and service agreements determine whether each slice 5G Network Architecture 43 may be assigned to shared or dedicated radio resources. To enable differentiated handling of traffic for network slices with different service agreements, NG-RAN is configured with a set of different configurations for different network slices and receives relevant information, indi- cating which of the configurations applies to each specific network slice. The NG-RAN selects the AMF based on a Temp ID or assistance information provided by the UE. In the event that a Temp ID is not available, the NG-RAN uses the assistance information provided by the UE at RRC connection establishment to select the appropriate AMF instance (i.e., the information is provided after random access procedure). If such information 