Core-Network S-NSSAI Mapping for NPN–PLMN Session Handover
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Solution Overview
Problem
Improving session continuity during handovers between non-public network (NPN) cells and PLMN cells, particularly in standalone (SA) and non-standalone (NSA) networking architectures, is a challenge due to the need for selecting appropriate network slices in the target access network device.
Innovation Solution
A core network device determines and provides first S-NSSAI to the target access network device based on second S-NSSAI and a mapping relationship, ensuring that the network slice in the target device can serve the session, thereby improving session continuity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If network slice selection is performed during handover between NPN and PLMN cells, then session continuity is improved, but the complexity of network slice management increases
Solution Approach 1:
The patent introduces a core network device as an intermediary that performs the complex task of determining the first S-NSSAI based on the second S-NSSAI and target network slice support. This mediator handles the complexity of network slice selection and mapping, while the access network devices and terminal devices can focus on their primary functions of signal transmission and reception, thus improving session continuity without significantly increasing the complexity at the edge devices
Solution Approach 2:
The patent performs preliminary determination of the first S-NSSAI by the core network device before the actual handover execution. The core network device proactively identifies the appropriate network slice in the target PLMN network based on the source NPN network's slice information and the target network's capabilities, preparing the handover parameters in advance to ensure seamless session continuity
2Reliability
If different S-NSSAI values are used in source and target access network devices, then session continuity is improved, but the difficulty of coordinating network slice selection increases
Solution Approach 1:
The core network device acts as a coordinating intermediary that receives the second S-NSSAI from the source access network device, determines the appropriate first S-NSSAI for the target network based on slice mapping relationships and target network capabilities, and provides this information to the target access network device. This intermediary coordination simplifies the overall process by centralizing the complex mapping logic
Solution Approach 2:
The patent transforms the network slice identification parameter from the source network's S-NSSAI (second S-NSSAI) to the target network's S-NSSAI (first S-NSSAI) through a mapping relationship maintained by the core network device. This parameter transformation allows the session to maintain continuity while adapting to different network architectures and slice naming conventions between NPN and PLMN networks
Data Source
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AI summary
This application provides a handover method and apparatus, which may be applied to handover of a terminal device between an NPN cell and a PLMN cell in an NSA architecture. The method includes: A source access network device learns that a session of a terminal device needs to be handed over from the source access network device to a target access network device, and sends, to a core network device, a handover requirement message that includes an identifier of the session; and after receiving the handover requirement message, the core network device learns of first S-NSSAI that is of a network slice and that is determined based on second S-NSSAI and a network slice supported by the target access network device, and sends a handover request message including the first S-NSSAI to the target access network device, where the second S-NSSAI is S-NSSAI that is of a network slice in the source access network device and that corresponds to the identifier of the session. S-NSSAI of a network slice that serves the session is determined in the target access network device, to improve session continuity.