UE Temporary Forbidden List Prevents Permanent Out of Service
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Solution Overview
Problem
User equipment (UE) enters a permanent out of service (OOS) state due to false registration reject causes from networks, especially when trying to access a visited Public Land Mobile Network (PLMN) not in contract with its home PLMN, leading to incorrect identification of registration reject causes.
Innovation Solution
A method and system where the UE stores network entity identifiers in a temporary forbidden list upon receiving a registration reject message with a permanent cause, preventing permanent OOS by skipping invalidation of the subscriber identity module (SIM) and automatically registering with a previously registered or available network entity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the network issues a registration reject message with a permanent cause when the UE tries to access a visited PLMN, then the network enforces contract restrictions, but the UE incorrectly enters into a permanent OOS state
Solution Approach 1:
The UE performs preliminary actions by storing network entity identifiers in a temporary forbidden list before attempting registration. This preventive measure allows the UE to identify false permanent cause rejections and avoid entering permanent OOS state by checking the forbidden list before registration attempts.
Solution Approach 2:
The temporary forbidden list acts as an intermediary mechanism between the network's registration reject messages and the UE's registration decisions. It mediates the interaction by providing contextual information about previously registered networks, enabling the UE to distinguish between legitimate and false permanent cause rejections.
2Measurement precision
If the UE stores network entity identifiers in a temporary forbidden list, then the UE can identify false registration rejections, but the device complexity increases
Solution Approach 1:
The temporary forbidden list is designed as a simple, temporary data structure that stores network entity identifiers only during the relevant period. It is cleared after a predetermined time or when no longer needed, avoiding the complexity of permanent storage mechanisms while providing sufficient functionality for identifying false rejections.
3Duration of action of stationary object
If the UE automatically registers with previously available networks, then service continuity is maintained, but the control logic becomes more complex
Solution Approach 1:
The UE performs self-service by automatically selecting and registering with previously available networks based on information stored in the temporary forbidden list. This autonomous behavior maintains service continuity without requiring complex external control logic, as the UE independently makes registration decisions based on its own stored history.
Data Source
AI summary
Methods and apparatuses are provided that prevent a user equipment (UE) from entering into a permanent out of service (OOS) state. The UE receives a registration reject message associated with a permanent cause when the UE triggers a registration request for registering with a first network entity. It is determined whether the UE was previously registered with a second network entity upon receiving the registration reject message associated with the permanent cause. The UE stores a network entity identifier of the first network entity in a temporary forbidden list when the UE was previously registered with the second network entity, to prevent the UE from entering into the permanent OOS state.