 support for the slice, availability of resources, and support of the requested service by NG-RAN. Support for UE associating with multiple network slices simultaneously: - In case a UE is associated with multiple slices simultaneously, only one signaling con- nection is maintained and for intra-frequency cell reselection, the UE always tries to camp on the best cell. For inter-frequency cell reselection, dedicated priorities can be used to control the frequency on which the UE camps. Granularity of slice awareness: - 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. Validation of the UE rights to access a network slice: - It is the responsibility of the 5GC to validate that the UE has the rights to access a network slice. Prior to receiving the initial context setup request message, the NG-RAN may be allowed to apply some provisional/local policies, based on the 12.3 RAN Subsystem Deployment Scenarios awareness of which slice the UE is requesting access to. During the initial context setup, the NG-RAN is informed of the slice for which resources are being requested. RAN Subsystem Deployment Scenarios The support of diverse vertical services with distinctly different requirements requires flex- ible RAN subsystem deployment. In particular, for shopping mall or factory automation, the deployment coverage could be limited with a few base stations, while for V2X services they may need larger area because of high mobility [8]. Flexible deployment alternatives are needed to adapt to the specific requirements while maintaining overall cost efficiency. Several examples are given as follows: Scenario 1: deployments on a single frequency band (cell/tracking area granularity): The example on a single frequency band is given in Figure 12.3, where subsystem1 is supported by all RAN nodes. RAN subsystem2 and subsystem3, with limited coverage requirements, are supported by different RAN nodes. S