DNAI-Based UPF Selection for 5G PDU Session Continuity
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Solution Overview
Problem
In next-generation wireless communications systems, such as 5G, service continuity cannot be ensured during the re-establishment of a PDU session, particularly in session and service continuity mode 2.
Innovation Solution
The method involves using a data network access identifier (DNAI) to determine and maintain the user plane network element consistently during PDU session establishment and re-establishment, ensuring that the DNAI associated with the application server remains unchanged, thereby ensuring service continuity between the application server and the terminal device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the UPF network element is determined based on policy rule information or location information during PDU session establishment, then the PDU session can be established, but service continuity cannot be ensured during PDU session re-establishment in SSC mode 2
Solution Approach 1:
The patent applies preliminary action by determining and selecting a target UPF network element before the PDU session re-establishment occurs. The SMF network element proactively identifies the appropriate UPF based on stored location information or policy rules, ensuring that when re-establishment is needed, the service can be quickly restored without service interruption. This pre-selection of the target UPF element resolves the contradiction by preparing the service continuity path in advance.
Solution Approach 2:
The patent introduces the SMF network element as an intermediary that mediates between the access network and the UPF network element during PDU session re-establishment. The SMF receives location information or policy rules, determines the appropriate target UPF, and manages the re-establishment process, ensuring service continuity. This intermediary role allows the system to maintain service continuity while managing the complexity of re-establishment procedures.
2Adaptability or versatility
If the terminal device moves to a different service area, then the terminal device can access new areas, but the DNAI associated with the application server changes, causing service disruption
Solution Approach 1:
The patent applies preliminary action by storing location information and policy rules before the terminal device moves to a different service area. When the device moves and DNAI changes, the SMF network element can quickly determine the appropriate target UPF based on the pre-stored information, maintaining service continuity. This pre-preparation of location and policy data allows the system to adapt to new service areas while preserving service reliability.
Solution Approach 2:
The patent utilizes parameter changes by dynamically adjusting the selection of UPF network elements based on changing location information and DNAI parameters. When the terminal device moves to a different service area, the system changes the relevant parameters (location, DNAI) and uses these updated parameters to determine the appropriate target UPF, ensuring that service continuity is maintained despite parameter changes.
Data Source
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AI summary
This application provides a communications method and apparatus. The method includes: receiving, by a policy control network element, a policy request message from a first session management network element; and sending, by the policy control network element, policy information to the first session management network element, where the policy information includes a data network access identifier DNAI, and the DNAI is configured to determine a first user plane network element for establishing a first protocol data unit PDU session for a terminal device.