Section: 5.4.4.3 Paging assistance information
Content: The paging assistance information contains UE radio related information that assists the RAN for efficient paging. The Paging assistance information contains: a) UE radio capability for paging information: - The UE Radio Capability for Paging Information contains information derived by the NG-RAN node (e.g. band support information) from the UE Radio Capability information. The AMF stores this information without needing to understand its contents. As the AMF only infrequently (e.g. at Initial Registration) prompts the NG-RAN to retrieve and upload the UE radio capabilities i.e. UE Radio Capability information to the AMF, and the AMF may be connected to more than one NG-RAN RAT, it is the responsibility of the NG-RAN to ensure that UE Radio Capability for Paging Information (which is derived by the NG-RAN node) contains information on all NG-RAN RATs that the UE supports in that PLMN. To assist the NG-RAN in this task, as specified in TS 38.413[ NG-RAN; NG Application Protocol (NGAP) ]  [34], the AMF provides its stored UE Radio Capability for Paging Information in every NG-AP INITIAL CONTEXT SETUP REQUEST message sent to the NG-RAN. - The UE Radio Capability for Paging Information is maintained in the core network, even during AMF reselection, and is stored in the UCMF alongside the UE Radio Capability information associated to a UE Radio Capability ID. b) Information On Recommended Cells And RAN nodes For Paging: - Information sent by the NG-RAN, and used by the AMF when paging the UE to help determining the NG RAN nodes to be paged as well as to provide the information on recommended cells to each of these RAN nodes, in order to optimize the probability of successful paging while minimizing the signalling load on the radio path. - The RAN provides this information during N2 release.