Access Terminal PLMN Selection Mode Switching
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Solution Overview
Problem
Access terminals face challenges in maintaining network connectivity when manually selecting a closed subscriber group (CSG) in a different public land mobile network (PLMN), as automatic PLMN selection modes may switch to higher priority networks, and manual modes can result in loss of service if no suitable cells are found within the selected PLMN.
Innovation Solution
The access terminal switches to a manual mode of PLMN selection upon selecting a CSG in a different PLMN and maintains a record of the current PLMN and selection mode, allowing it to remain on the selected PLMN and automatically switch back if coverage is lost, and reselect the CSG if returned within a defined period.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If automatic PLMN selection mode is used, then the access terminal can automatically switch to higher priority networks, but the access terminal cannot remain camped on a selected CSG in a different PLMN
Solution Approach 1:
The patent extracts the PLMN selection functionality from the automatic selection mode and creates a separate manual selection mode specifically for CSG scenarios. When a CSG is selected, the system suspends automatic PLMN selection and transitions to manual mode, preventing the automatic mode from interfering with CSG camping stability.
Solution Approach 2:
The system dynamically switches between automatic and manual PLMN selection modes based on the operational context. When a CSG is selected, the mode changes from automatic to manual; when the CSG is no longer selected, it returns to automatic mode. This dynamic adaptation resolves the contradiction by having the system behave differently under different conditions.
2Stability of the object's composition
If manual PLMN selection mode is used, then the access terminal can remain on the selected PLMN, but the access terminal will be without service if no suitable cell is found in the selected PLMN
Solution Approach 1:
The system takes preliminary action by storing the previous PLMN selection mode before switching to manual mode for CSG selection. This stored information is preserved and used to automatically restore the previous mode after CSG selection, preventing the system from being stuck in manual mode where it cannot adapt to service availability changes.
Solution Approach 2:
The system implements feedback by monitoring CSG selection status and automatically adjusting PLMN selection mode accordingly. When CSG selection ends, the system detects this change and feeds back by restoring the previous automatic selection mode, ensuring the system adapts to current operational needs while maintaining stability during CSG operation.
3Reliability
If the access terminal switches to manual mode upon CSG selection, then seamless connectivity is maintained, but the device complexity increases due to mode switching logic
Solution Approach 1:
The patent merges the PLMN selection mode management with the CSG selection process. The mode switching is not a separate independent function but is integrated into the CSG selection and deregistration workflows. When CSG is selected, manual mode is activated; when CSG deregisters, automatic mode is restored. This integration reduces overall system complexity by combining related functions.
Data Source
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AI summary
An access terminal may switch to a different mode of wireless network selection as a result of manual selection of a wireless cell set (e.g., a closed subscriber group) associated with one or more wireless cells. For example, if the user of an access terminal selects a closed subscriber group in a wireless network that is different than the current wireless network, the access terminal may enter a manual mode of wireless network selection, select the wireless network corresponding to the closed subscriber group, and register on a closed subscriber group cell in the selected wireless network. In addition, an access terminal may automatically switch to a different mode of wireless network selection (e.g., the prior mode) upon losing coverage of a wireless cell set. An access terminal may also automatically select a cell of a wireless cell set if the access terminal returns to a cell of the cell set within a defined period of time after losing coverage of the cell set. Furthermore, an access terminal may return to a prior wireless network upon losing coverage of a wireless cell set.