Abstract: Examples described herein relate to techniques for session continuity when a User Equipment (UE) is moving to a destination core of a destination communication system in an interworking network architecture. Example techniques may include registering by a destination subscription manager in a Network Repository Function (NRF) a subscription profile and indicating support for a session continuity for the User Equipment (UE). Discovering the subscription profile by a source subscription manager by utilizing the NRF. Receiving the session information by the destination subscription manager from the source subscription manager based on the discovery of the subscription profile. Enabling continuity of the session by the destination subscription based on the received session information.

Abstract: Systems and methods are provided for identifying an alternative network function (NF) service consumer to which a notification regarding an observed event may be sent (in the event that a notification sent to an originally-intended/targeted NF service consumer fails). NF discovery request and response operations between a NF service producer and a data repository (at which a NF profile associated with the NF service consumer is registered) may be performed to identify and receive (as part of a NF discovery response operation), binding indication information. The binding information may be used to determine the aforementioned, alternative NF service consumer to receive the notification.

Abstract: Systems and methods are provided for optimizing session continuity management during 5th Generation (5G) and 4G/Long Term Evolution (LTE) interworking. Conventional 4G/LTE and 5G interworking involves session continuity subscription or retrieval operations to obtain the latest mobility data for a user equipment (UE) attempting to attach to a particular communications network. These operations include exchanging various messages can be avoided by determining the existence of an Authentication, Authorization, Accounting (AAA)/evolved Packet Data Network Gateway (ePDG) registration (among other conditions).

Abstract: 5G provides for interworking with the 4G/LTE networks, which provides for mobility of user equipment between the 5G and 4G/LTE networks. Mobility from 5G to 4G/LTE requires deregistering user equipment from the 5G core network (5GC) by communicating a deregistration notification from the Evolved Packet Core (EPC) to the 5GC. Systems and methods disclosed herein provide for an optimized deregistration process through avoidance of redundant deregistration notification traffic injected into the 5G network by utilizing 4G/LTE connectivity information to determine whether or not to inject deregistration notifications into the 5G network.

Abstract: Systems and methods are provided for automatic notifications of expired subscriptions. In various embodiments, a network function can request a subscription from a Unified Data Repository (UDR). The request for the subscription can include a request for a notification when the subscription expires or at a time prior to the expiration of the subscription. When the subscription expires or at the time prior to the expiration of the subscription, the UDR can provide a notification that the subscription has expired or is about to expire. Based on the notification, the network function can request to re-subscribe or request a new subscription from the UDR.

Abstract: The systems and method disclosed herein optimize the deregistration of user equipment (UE) from the 5GC. For example, when the UE operates in single-registration mode, for AMF 3GPP access registration with drFlag attribute set to false (or to be absent) in UDM/UDR, a “new attribute”, singleRegIndication, is defined. The AMF sets the singleRegIndication value to “NO_INDICATION” when there is no N26 interface connection to MME. UDM will not instruct HSS to cancel MME (and SGSN/VLR) if there is an old AMF 3GPP registration for which “NO_INDICATION” or “DEREGISTER_SN” is set as the singleRegIndication value (i.e. the old AMF was already registered with the single registration). Otherwise, the AMF sets the singleRegIndication value to “DEREGISTER_SN” when the AMF has established a N26 interface connection to the old MME. UDM can instruct HSS to cancel the MME (and SGSN/VLR).