AMF-Coordinated Network Slice Handover With PDU Session Control
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Solution Overview
Problem
In 3GPP LTE systems, transitioning a user equipment (UE) between network slices results in unnecessary signaling and prolonged service interruption due to the release and re-establishment of PDU sessions, especially when moving between NG-RAN nodes supporting different network slices.
Innovation Solution
The proposed solution involves an AMF and RAN node communication method that includes receiving PDU session establishment requests, determining network slice support, and coordinating handovers to minimize signaling by deactivating the first PDU session and establishing the second PDU session efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the UE moves to a second NG-RAN supporting a different network slice, then the UE can access the desired network slice, but unnecessary signaling occurs and service interruption time increases due to PDU session release and re-establishment
Solution Approach 1:
The AMF performs preliminary actions by determining target RAN node information before the handover is complete, and prepares the PDU session deactivation request in advance. This allows the network to prepare for the slice transition beforehand, reducing the actual service interruption time when the UE moves to the second NG-RAN.
Solution Approach 2:
The AMF acts as an intermediary between the RAN nodes and the SMF, coordinating the handover process and managing PDU session state transitions. By introducing the AMF as a mediator that handles the coordination between RAN relocation and PDU session management, the system reduces signaling overhead and optimizes the timing of session deactivation/reactivation.
2Adaptability or versatility
If the UE moves to a second NG-RAN supporting a different network slice, then the UE can access the desired network slice, but unnecessary signaling occurs due to PDU session release and re-establishment
Solution Approach 1:
The AMF serves as an intermediary that consolidates and coordinates the signaling between RAN nodes and the SMF during handover. By centralizing the control logic in the AMF, the system reduces redundant signaling messages and optimizes the sequence of operations, thereby reducing overall signaling complexity while maintaining network slice adaptability.
3Adaptability or versatility
If the PDU session is released during handover to a different network slice, then the network can allocate resources for the new slice, but the UE experiences service interruption and must re-establish the session
Solution Approach 1:
The network performs preliminary determination of target RAN node information and prepares PDU session deactivation requests before the handover is fully executed. This preliminary action allows for smoother resource allocation to the new network slice while minimizing the impact on service continuity, as the transition is pre-coordinated rather than reactive.
Data Source
AI summary
One disclosure of the present specification provides a method by which an AMF performs communication related to a network slice. The method may comprise the steps of: receiving a PDU session establishment request message including information about a second PDU session; determining to forward a UE to a second RAN node supporting a second network slice; transmitting a message including information indicating that the UE needs to be forwarded to the second RAN node supporting the second network slice; receiving a handover required message; and transmitting a request message for deactivating the first PDU session related to a first network slice.