LTE to 5G Handover via S-NSSAI Mapping
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Solution Overview
Problem
Inter-system mobility between Long-term Evolution (LTE) and fifth generation (5G) networks poses challenges for seamless service continuity as existing technologies lack effective methods to manage network slice selection and PDU session identity during handovers.
Innovation Solution
A communication device and method that utilize Single Network Slice Selection Assistance Information (S-NSSAI) to facilitate seamless handovers by transmitting slice information between LTE and 5G networks, enabling the selection of appropriate network slices and PDU sessions based on service requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If inter-system mobility between LTE and 5G networks is implemented without effective slice selection management, then device mobility is enabled, but service continuity cannot be ensured
Solution Approach 1:
The patent applies preliminary action by pre-establishing the mapping relationship between PDN connections and network slices before handover occurs. The source AMF determines and stores the correspondence between EPS bearers and 5G QoS flows in advance, so that during handover the target AMF can directly utilize this pre-established mapping without complex real-time calculations, ensuring service continuity while managing complexity.
Solution Approach 2:
The patent uses the AMF (Access and Mobility Management Function) as an intermediary entity that manages the complexity of slice selection. The source AMF determines the mapping between PDN connections and network slices, and the target AMF retrieves this information during handover. This intermediary approach centralizes the complex slice selection logic, enabling service continuity without distributing complexity across multiple nodes.
2Reliability
If PDU session identity is not properly determined during handover, then handover procedure is simplified, but PDU session establishment fails
Solution Approach 1:
The patent applies preliminary action by pre-determining the PDU session identity during the initial PDN connection establishment in the LTE network. The source AMF stores the mapping between EPS bearer identities and PDU session identities before handover. During handover, the target AMF retrieves this pre-determined identity without needing to create new sessions, ensuring reliable PDU session establishment while keeping the handover procedure relatively simple.
Solution Approach 2:
The patent uses copying by transferring the PDU session identity information from the source AMF to the target AMF during handover. Instead of重新 creating PDU sessions, the target AMF copies the existing session identities and their mappings from the source network, ensuring session continuity with minimal complexity in the handover procedure.
3Reliability
If network slice information is not transmitted during handover, then signaling overhead is reduced, but network slice selection cannot be maintained
Solution Approach 1:
The patent extracts only the essential slice selection information (S-NSSAI) from the complete network slice configuration and includes it in the handover signaling. By extracting only the critical slice identifier rather than transmitting entire slice configuration data, the patent maintains network slice selection capability while minimizing the increase in signaling message size.
Solution Approach 2:
The patent makes the handover signaling message universal by incorporating it with multiple functions: it performs the standard handover coordination while simultaneously transmitting the network slice selection information (S-NSSAI). This multi-functionality allows the same signaling mechanism to handle both handover execution and slice information transfer, reducing the need for separate dedicated slice information messages.
Data Source
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AI summary
A communication device for handling mobility from a long-term evolution (LTE) network to a fifth generation (5G) network comprises a storage device storing instructions of transmitting a first LTE Non-Access Stratum (NAS) message to the LTE network; receiving a second LTE NAS message in response to the first LTE NAS message, from the LTE network; and transmitting a message to the 5G network, after determining to communicate with the 5G network instead of the LTE network, wherein the message comprises a slice information, and the slice information is comprised in the first LTE NAS message or in the second LTE NAS message.