UE PLMN Selection Upon Network Slice Authentication Failure
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Solution Overview
Problem
In a roaming environment, network slice specific authentication failures lead to unnecessary Public Land Mobile Network (PLMN) selection, resulting in inefficient PLMN selection processes due to the lack of efficient methods to determine and exclude PLMNs with failed network slice authentication.
Innovation Solution
A method where a User Equipment (UE) generates and transmits a second registration request message using default configured Network Slice Selection Assistance Information (NSSAI) not included in the rejected NSSAI, allowing it to efficiently select a PLMN with available network slices, thereby avoiding repeated access failures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the UE repeatedly performs PLMN selection after network slice authentication failure, then the UE may eventually find a suitable network, but the PLMN selection process becomes inefficient and time-consuming
Solution Approach 1:
The UE performs preliminary analysis of the rejection cause value before initiating PLMN selection. When the cause value indicates network slice authentication failure, the UE proactively excludes the current PLMN from future selection attempts and uses default configured NSSAI to identify alternative PLMNs, thereby avoiding repeated failed authentication attempts and reducing overall selection time
Solution Approach 2:
The UE utilizes feedback from the registration reject message (cause value and rejected NSSAI) to adjust its PLMN selection behavior. By analyzing the authentication failure indication and default configured NSSAI, the UE makes informed decisions about which PLMNs to exclude and which alternative PLMNs to attempt, creating a feedback loop that improves selection efficiency
2Adaptability or versatility
If the UE performs standard PLMN selection procedures after authentication failure, then all available PLMNs are evaluated, but unnecessary PLMN selection attempts are made to PLMNs with failed network slice authentication
Solution Approach 1:
The UE extracts and excludes PLMNs with failed network slice authentication from the PLMN selection list based on the rejection cause value. By removing these unsuitable PLMNs before attempting connection, the UE avoids unnecessary selection attempts while maintaining adaptability to evaluate remaining PLMNs using default configured NSSAI
Solution Approach 2:
The UE changes the selection criteria by incorporating the rejection cause value and default configured NSSAI into the PLMN selection process. This parameter change allows the UE to differentiate between PLMNs based on authentication failure patterns, improving selection efficiency without sacrificing network compatibility
Data Source
AI summary
Provided are a method and device for efficient public land mobile network (PLMN) selection upon authentication failure for each network slice in a roaming network. A user equipment (UE) receives a registration rejection message from an access and mobility management function (AMF) of a first PLMN. The registration rejection message includes rejected network slice selection assistance information (NSSAI) including first single NSSAI (S-NSSAI) and cause value #62 for the rejected NSSAI. The UE: generates second requested NSSAI including second S-NSSAI on the basis that i) the UE does not have allowed NSSAI and configured NSSAI, and ii) default configured NSSAI includes the second S-NSSAI that is not included in the rejected NSSAI and corresponds to a network slice of which the UE requests registration; and transmits a second registration request message including the second requested NSSAI to the AMF of the first PLMN.