UE Backoff Timer Handling for NPN Localized Services
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Solution Overview
Problem
In wireless mobile communication networks, especially in non-public networks (NPNs), there is a challenge in managing access to localized services due to the lack of effective mechanisms for handling congestion timers, which can lead to unauthorized access and network overload, particularly when UE validity information and backoff timers are not properly managed.
Innovation Solution
A method for handling backoff timers is proposed, where user equipment (UE) checks validity information associated with the NPN, such as SNPN, GIN, or CAG, to determine authorization during and after the backoff timer period, triggering network selection to another PLMN or NPN if the timer expires beyond the validity time, ensuring authorized access to localized services.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the UE continues to attempt network registration after receiving a backoff timer, then the UE can potentially access the network faster, but it causes network overload and unauthorized access
Solution Approach 1:
The UE performs preliminary actions by checking validity information (such as CAG list, SNPN configuration, and service acceptance status) before attempting network registration. This preliminary validation ensures that the UE only attempts to register to networks where it is authorized, preventing unauthorized access while maintaining efficient network access for legitimate users.
Solution Approach 2:
The system implements feedback mechanisms where the network provides backoff timers and validity information to the UE, and the UE uses this feedback to adjust its registration behavior. The UE monitors the backoff timer status and validity information updates, and only attempts registration when the backoff has expired and validity criteria are met, thereby preventing network overload while allowing legitimate access.
2Reliability
If the UE checks validity information frequently, then access authorization is more accurate, but device complexity and processing overhead increase
Solution Approach 1:
The UE utilizes multi-functionality by employing a unified validity check mechanism that serves multiple purposes: checking CAG membership, verifying SNPN authorization, and validating service acceptance status. This single validity information structure handles multiple authorization scenarios, reducing the need for separate checking mechanisms and thereby lowering device complexity while maintaining comprehensive access control accuracy.
Data Source
AI summary
A method of backoff timer handling for accessing a hosting network for localized services is proposed. When a UE receives a NAS message from an NPN hosting network with a backoff timer, the UE needs to determine whether it can register to the NPN as a hosting network for localized services while the backoff timer is running. The UE checks the validity information associated with the NPN, e.g., an SNPN/GIN/CAG, and determines whether the UE is still authorized to access the NPN upon/after backoff timer expiry. In one example, if the current time+the remaining length/duration of the backoff timer is longer than the end of the validity time of the NPN, then the UE triggers the network selection (SNPN selection or PLMN selection) and registers to another PLMN, PNI-NPN/CAG or SNPN for access for localized services, or just for normal services (non-localized services).