Session Management for Seamless Network Function Reselection
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Solution Overview
Problem
Current solutions for handling path failures in CUPS architecture, such as Sxb/N4 failures, result in significant signaling load and user experience degradation due to the need to delete and re-establish packet data network connections, or incur high costs with 1+1 redundancy, compromising service continuity and network efficiency.
Innovation Solution
Implementing a method where the PGW-C or SMF reselects a new PGW-U or UPF with a higher routing priority for the UE's IP address, allowing seamless service continuity without deleting existing connections, thereby reducing signaling load and operational costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the existing solution releases the old PDN connection and re-establishes the new connection upon path failure, then service continuity is maintained, but significant signaling load is generated and user experience is degraded
Solution Approach 1:
The patent applies preliminary action by pre-establishing backup user plane network functions (PGW-U or UPF) before path failure occurs. When a path failure is detected, the system can immediately switch to the pre-prepared backup function without needing to release and re-establish connections, thus maintaining service continuity while avoiding the signaling storm that would otherwise occur.
Solution Approach 2:
The patent uses copying by creating redundant copies of user plane network functions (PGW-U or UPF) that can immediately take over when the primary function fails. These backup copies are prepared in advance and can assume the session roles without requiring connection teardown and re-establishment, thereby reducing signaling load while ensuring service continuity.
2Reliability
If 1+1 redundancy is implemented for UP function, then service continuity is ensured, but operational costs increase significantly
Solution Approach 1:
The patent applies partial action by implementing selective redundancy only where absolutely necessary for service continuity, rather than universal 1+1 redundancy across all user plane functions. The system prepares backup PGW-U or UPF functions that can be activated upon failure, providing the necessary reliability while avoiding the excessive operational costs of maintaining full redundancy for all functions simultaneously.
Solution Approach 2:
The patent uses the principle of disposable objects by implementing backup user plane functions that can be quickly activated and then replaced. The backup PGW-U or UPF functions serve their purpose during failure scenarios and can be deactivated or replaced without significant cost, providing cost-effective service continuity compared to permanent 1+1 redundancy arrangements.
3Adaptability or versatility
If PDN connection is deleted and re-established, then a new user plane network function can be selected, but session continuity is interrupted and user experience is compromised
Solution Approach 1:
The patent uses an intermediary approach by introducing a session management function that acts as a mediator between the user equipment and the user plane network functions. This intermediary can seamlessly transfer sessions between different PGW-U or UPF functions without requiring the user equipment to detect or experience the transition, thus enabling flexible user plane function reselection while maintaining uninterrupted service and preserving user experience.
Data Source
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AI summary
Embodiments of the present disclosure provide methods and apparatuses for session management. A method implemented at a first network function (NF) may comprise detecting that a path between the first NF and a second NF is failed or the second NF is failed, wherein the second NF maintains one or more data network connections or sessions established between one or more user equipments (UEs) and one or more data networks; selecting an available second NF for the at least one of the one or more data network connections or sessions; sending at least one address or address range of at least one UE corresponding to the at least one of the one or more data network connections or sessions and respective priority metric of the at least one address or address range to the available second NF.