MA-PDU Session Handover via AMF Relocation in 5G Networks
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Solution Overview
Problem
Current solutions are inadequate for managing mobility and session continuity in multi-access protocol data unit (MA-PDU) sessions, particularly when involving both 3GPP and non-3GPP access networks, as they fail to efficiently handle handovers and traffic distribution across different network types.
Innovation Solution
The implementation of Xn-based and N2-based handover procedures with Access and Mobility Management Function (AMF) relocation, where the WTRU assists in switching data traffic from one access network to another, allowing for seamless handover and session continuity by informing the target AMF about multi-access PDU sessions and relocating the user plane functions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional handover procedures are used for MA-PDU sessions, then single-access session management is maintained, but mobility handling and session continuity are inadequate across multiple access networks
Solution Approach 1:
The patent segments the handover procedure into distinct phases: source AMF identifies MA-PDU sessions, separates control plane and user plane functions, and directs target AMF to handle user plane relocation. This segmentation enables specialized handling of multi-access sessions while maintaining compatibility with traditional single-access procedures.
Solution Approach 2:
The source AMF acts as an intermediary that identifies MA-PDU sessions and initiates the handover procedure by sending Handover Required messages to the target AMF. The target AMF then coordinates user plane function relocation, serving as a mediator between the source and target access networks to ensure seamless session continuity.
2Reliability
If traffic is switched during handover, then session continuity is achieved, but data loss and latency increase
Solution Approach 1:
The source AMF performs preliminary identification of MA-PDU sessions before the handover is fully executed. By proactively preparing the handover procedure and pre-coordinating user plane function relocation with the target AMF, the system minimizes the actual traffic switching time and reduces data loss during handover.
Solution Approach 2:
The patent maintains continuous user plane connectivity by relocating user plane functions to the target AMF during handover. This ensures that data traffic flows continuously without interruption, eliminating gaps that would cause data loss while maintaining session continuity across access networks.
3Device complexity
If simple handover procedures are used, then implementation complexity is reduced, but traffic distribution management across different network types is ineffective
Solution Approach 1:
The patent extends the existing handover procedure framework to handle both single-access and multi-access PDU sessions. By adding MA-PDU session identification and user plane function relocation capabilities to the traditional handover mechanism, the system achieves multi-functionality without creating entirely separate procedures, thus balancing complexity and adaptability.
Data Source
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AI summary
Methods, apparatuses, systems, etc. for handling mobility in connection with protocol data unit (PDU) sessions are provided. Among these is a wireless transmit/receive unit (WTRU) that may receive, from a source access network (S-AN), a handover command in connection with a handover involving a multi-access protocol PDU (MA-PDU) session having one of first and second access legs associated with the S-AN. The WTRU may determine that the second access leg should be associated to the S-AN for the handover. The WTRU may send a session modification message to request modification of the MA-PDU session to cause the second access leg to become associated with S-AN The WTRU may establish a radio resource control connection with a target AN (T-AN), and the first and second access legs (e.g., as a combined access leg) may be associated with the T-AN.