Section: 4.3.31 Subscription handling for Aerial UEs
Content: This clause describes subscription information handling in order to support operating Aerial UE function over E-UTRAN as defined in TS 36.300[ Evolved Universal Terrestrial Radio Access (E-UTRA) and Evolved Universal Terrestrial Radio Access Network (E-UTRAN); Overall description; Stage 2 ]  [5] and TS 36.331[ Evolved Universal Terrestrial Radio Access (E-UTRA); Radio Resource Control (RRC); Protocol specification ]  [37]. The eNodeB supporting Aerial UE function handling uses the per user information supplied by the MME to determine whether or not to allow the UE to use Aerial UE function. Support of Aerial UE function is stored in the user's subscription information in HSS. HSS transfers this information to the MME via Update Location message during Attach and Tracking Area Update procedures. Home Operator may revoke user's subscription authorisation for operating Aerial UEs at any time. MME that supports Aerial UE function provides the user's subscription information on Aerial UE authorisation to the eNodeB via the S1 AP Initial Context Setup Request during Attach, Tracking Area Update and Service Request procedures. For the intra and inter MME S1 based handover (intra RAT) or Inter-RAT handover to E-UTRAN, the Aerial UE subscription information for the user is included in the S1-AP UE Context Modification Request message sent to the target eNodeB after the handover procedure. For X2-based handover, the Aerial UE subscription information for the user is sent to target eNodeB as follows: - If the source eNodeB supports Aerial UE function and the user's Aerial UE subscription information is included in the UE context, the source eNodeB shall include the information in the X2-AP Handover Request message to the target eNodeB. - The MME shall send the Aerial UE subscription information to the target eNodeB in the Path Switch Request Acknowledge message. If the Aerial UE subscription information has changed, the updated Aerial UE subscription information is included in the S1-AP UE Context Modification Request message sent to the eNodeB.