Session Service Area for 5G User Plane Path Re-establishment
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Solution Overview
Problem
In 5G mobile communications, the existing standards lack a clear mechanism for initiating user plane path re-establishment, which is necessary to maintain effective data communication for mobile terminal devices due to the flexible deployment of User Plane Functions (UPFs) and separate mobility and session management entities.
Innovation Solution
A method and apparatus for initiating user plane path re-establishment, where a Session Management Function entity determines a session service area for a terminal device and instructs it to initiate a handover or re-establishment procedure when the device moves out of this area, using location information from a Mobility Management Function entity, thereby reducing ping-pong effects and improving user experience.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a terminal device moves in a flexible UPF deployment environment with separate mobility and session management, then the ability to serve mobile terminals is improved, but frequent handovers between UPFs occur causing ping-pong effects
Solution Approach 1:
The patent applies preliminary action by establishing a session service area for each PDU session before the terminal device moves. The SMF determines the session service area based on the UPF service area and terminal location, and proactively monitors whether the terminal remains within this area. This preliminary setup prevents the ping-pong effect by having handover criteria ready in advance rather than reacting to continuous location changes.
Solution Approach 2:
The patent implements feedback mechanisms where the AMF reports terminal location information to the SMF, and the SMF continuously monitors whether the terminal has moved out of the session service area. This feedback loop allows the system to detect handover conditions only when necessary, preventing unnecessary handovers while maintaining the ability to respond to actual service area violations.
2Reliability
If user plane path re-establishment is initiated frequently to maintain effective data communication, then communication effectiveness is improved, but network signaling overhead increases
Solution Approach 1:
The patent applies preliminary action by pre-defining the session service area boundaries before terminal movement occurs. The SMF determines the session service area based on the UPF service area and initial terminal location, establishing clear handover criteria in advance. This prevents unnecessary path re-establishment by having predetermined conditions that must be met before initiating handover.
Solution Approach 2:
The patent uses partial action by implementing location report granularity, where the AMF reports terminal location to the SMF only at specific granularities rather than continuously. The SMF determines whether to trigger handover based on whether the terminal has moved out of the session service area at these reported locations, reducing signaling overhead while maintaining effective communication.
Data Source
AI summary
A method and an apparatus for initiating user plane path re-establishment and a communications system are disclosed. The method includes: determining, by a session management function entity based on first location information of a terminal device, a session service area to which a current session of the terminal device belongs; and after receiving second location information of the terminal device sent by a mobility management function entity, if determining that the second location information is not within the session service area, instructing the terminal device to initiate a re-establishment procedure for the current session or initiate a handover procedure. Due to introduction of the session service area, when the terminal device moves back and forth at edges of service areas of two adjacent user plane function entities, a ping-pong effect caused by frequent handover between the two user plane function entities is avoided, and user experience is improved.