Core-Network Slice Mapping for Cross-Network 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.
Innovation Solution
A handover method involving a core network device that determines and communicates first S-NSSAI to a target access network device based on second S-NSSAI and a mapping relationship, ensuring the network slice in the target device can serve the session, thereby enhancing session continuity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If network slice selection assistance information (S-NSSAI) is directly transferred from source to target access network device during handover, then the handover process is simple, but session continuity cannot be guaranteed when the target device does not support the same network slice
Solution Approach 1:
The core network device performs preliminary action by determining the first S-NSSAI based on the second S-NSSAI and the network slice supported by the target access network device before the handover is executed. This advance preparation ensures that the target device receives appropriate network slice information that guarantees session continuity, while avoiding the need for complex real-time negotiations during handover.
Solution Approach 2:
The core network device acts as an intermediary between the source and target access network devices. It receives the second S-NSSAI from the source device, maps it to the first S-NSSAI that is compatible with the target device's supported network slices, and then provides this mapped information to the target device. This intermediary role simplifies the handover process while ensuring session continuity.
2Adaptability or versatility
If the target access network device is required to support the same network slice as the source device, then session continuity is maintained, but the system lacks flexibility for inter-network handovers
Solution Approach 1:
The invention changes the parameter of network slice identification by introducing a mapping relationship between the second S-NSSAI (from source device) and the first S-NSSAI (for target device). This parameter transformation allows the system to maintain session continuity while adapting to different network slice configurations in the target device, thereby enabling flexible inter-network handovers.
Solution Approach 2:
The core network device implements a universal mapping mechanism that can handle multiple scenarios: when network slices are identical, when they differ, and when the target device supports different network slice configurations. This multi-functional mapping approach enables the system to maintain session continuity across diverse network environments without requiring the target device to support the exact same network slice as the source.
Data Source
AI summary
A handover method includes receiving a handover requirement message from a source access network device, and sending a handover request message to the target access network device. The handover requirement message includes an identifier of a session of a terminal device. The session is to be handed over from the source access network device to a target access network device. The handover request message includes first single network slice selection assistance information (S-NSSAI). A first network slice of the target access network device that corresponds to the first S-NSSAI serves the session. The first S-NSSAI is determined based on second S-NSSAI and the first network slice supported by the target access network device, and the second S-NSSAI is of a second network slice of the source access network device and that corresponds to the identifier of the session.