Default S-NSSAI Determination for Wireless Device PDU Sessions
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Solution Overview
Problem
In 5G systems, there is no explicit method for a User Equipment (UE) to determine a default Single Network Slice Selection Assistance Information (S-NSSAI), leading to ambiguity in establishing Protocol Data Unit (PDU) sessions without S-NSSAI association, and the UE Route Selection Policy (URSP) is complex, making it difficult for vendors to implement.
Innovation Solution
The proposed solution involves determining a default S-NSSAI by registering with a network node without providing a requested NSSAI, receiving allowed or marked S-NSSAIs from the network, and using these to establish a PDU session in the default network slice, thereby eliminating ambiguity and simplifying the implementation complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If URSP is used to associate applications with S-NSSAIs, then application-specific network slice selection is improved, but device complexity and implementation difficulty increase
Solution Approach 1:
The patent extracts the default S-NSSAI selection logic from the complex URSP framework by introducing a separate default S-NSSAI indicator that is independently determined and stored. This allows applications without URSP association to use the default S-NSSAI while URSP-based applications continue to use their specific associations, thereby reducing implementation complexity for basic cases while preserving adaptability for advanced cases.
Solution Approach 2:
The patent segments the S-NSSAI selection process into two distinct paths: (1) applications with URSP association use their specific S-NSSAI from URSP rules, and (2) applications without URSP association use the default S-NSSAI. This segmentation simplifies the decision logic by creating clear separation between URSP-based and non-URSP-based application handling.
2Ease of operation
If no requested NSSAI is provided during registration, then registration simplicity is improved, but ambiguity in PDU session establishment increases
Solution Approach 1:
The patent applies preliminary action by having the UE determine and store a default S-NSSAI during the registration phase (before PDU session establishment). The UE requests the default S-NSSAI indicator from the network during registration, stores it locally, and then uses this pre-determined default S-NSSAI for any application that does not have a specific URSP association. This eliminates ambiguity at the time of PDU session establishment while maintaining registration simplicity.
3Adaptability or versatility
If multiple S-NSSAIs are registered in allowed NSSAI, then network slice flexibility is improved, but difficulty in selecting the appropriate S-NSSAI increases
Solution Approach 1:
The patent applies local quality by assigning different selection criteria to different applications: applications with URSP association use their specific S-NSSAI determined by URSP rules, while applications without URSP association use the default S-NSSAI. This localized selection strategy simplifies the decision process for each application type while maintaining overall system flexibility.
Data Source
AI summary
Methods for determining a default network slice are provided. More specifically, the methods include determining a default Single Network Slice Selection Assistance Information (S-NSSAI) that identifies the default network slice for establishing a Protocol Data Unit (PDU) session for an application in a wireless device without an S-NSSAI association. Various embodiments for determining the S-NSSAI are also disclosed herein. By determining the default network slice, it is possible to eliminate existing ambiguity associated with establishing a PDU session for application without S-NSSAI association, thus helping to reduce implementation complexity in a wireless device and/or a core network node.