Selective RAN Handover Based on N26 Interface Availability
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Solution Overview
Problem
The N26 interface between 5G and LTE systems may be permanently or temporarily unavailable due to equipment failures, user equipment type, subscription limitations, or roaming status, leading to challenges in maintaining seamless handovers and call sessions.
Innovation Solution
Implementing a system that selectively performs handovers or redirects based on the availability of the N26 interface by storing and updating interface availability information in RANs, allowing handovers via available interfaces or redirects through shared network entities when the N26 interface is unavailable.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If handover is attempted via N26 interface, then seamless session continuity is achieved, but the system becomes vulnerable to interface unavailability due to equipment failures, user equipment type, subscription limitations, or roaming status
Solution Approach 1:
The system performs preliminary actions by storing interface availability information in RANs before handover occurs. The RAN stores whether the N26 interface is available to the UE based on equipment type, subscription status, and roaming conditions. This advance preparation allows the RAN to make informed handover decisions without attempting the handover first, thereby avoiding failures due to interface unavailability while maintaining seamless session continuity when the interface is available.
2Device complexity
If the system always attempts handover via N26 interface, then handover procedure is simplified, but session continuity is broken when N26 interface is unavailable
Solution Approach 1:
The RAN performs preliminary action by pre-storing interface availability information before handover decisions are made. This allows the system to simplify the handover procedure by having the availability information ready in advance, while simultaneously ensuring session continuity is maintained by avoiding handover attempts when the N26 interface is unavailable, thus resolving the contradiction between procedure simplicity and session continuity reliability.
Solution Approach 2:
The system implements feedback mechanisms where the RAN uses stored interface availability information to determine whether to proceed with handover via N26 interface or redirect through shared network entities. This feedback loop ensures that handover decisions are based on current interface availability status, maintaining session continuity while managing procedure complexity through informed decision-making.
3Reliability
If interface availability information is stored and updated in RANs, then handover quality is improved, but system complexity increases
Solution Approach 1:
The RAN performs self-service by storing and updating interface availability information autonomously based on equipment type, subscription status, and roaming conditions. The RAN independently maintains this information without requiring external intervention, thereby improving handover quality through locally-available accuracy information while minimizing the complexity increase by avoiding the need for complex centralized management systems.
Data Source
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AI summary
A first radio access network (RAN) accesses information indicating an availability status of an interface between an access and mobility management function (AMF) in a first wireless communication system and a mobility management entity (MME) in a second wireless communication system. The first RAN receives a trigger for a handover of a user equipment between the first RAN and a second RAN. The handover is selectively performed via the interface or a redirect via a network element shared by the first and second wireless communication systems based on the availability status. In some cases, the first RAN receive the information indicating the availability status prior to providing the request for the handover and stores the information in a database associated with the first RAN, which access the information from the database.