Segmented CSG List for Mobile Device Access Control
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Solution Overview
Problem
In LTE wireless communication systems, the current method of CSG identity comparison is inefficient, leading to delays in cell selection and reselection procedures due to unnecessary comparisons across different radio access technologies (RATs), which can cause handover delays and radio link failures.
Innovation Solution
Incorporating RAT information into the Allowed CSG list and Operator CSG list to maintain separate sub-allowed CSG lists for each RAT, allowing the mobile device to compare CSG identities only within the relevant RAT, thereby reducing unnecessary comparisons.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the UE compares CSG ID with all entries in the allowed CSG list without RAT filtering, then the UE ensures comprehensive access control checking, but the comparison time increases and cell selection/reselection is delayed
Solution Approach 1:
The allowed CSG list is segmented into multiple sub-lists based on RAT types (e.g., LTE sub-list, WCDMA sub-list). Each sub-list contains only CSG IDs relevant to a specific RAT. During cell selection or reselection, the UE selects the appropriate sub-list based on the current RAT and performs comparison only within that sub-list, eliminating unnecessary comparisons with CSG IDs from other RATs while maintaining comprehensive access control.
2Reliability
If the UE performs preliminary access check for all measured CSG cells, then the UE prevents unauthorized access attempts, but the handover preparation is delayed due to unnecessary checks
Solution Approach 1:
The allowed CSG list is divided into RAT-specific sub-lists. During measurement reporting, the UE identifies the RAT of the measured CSG cell and performs preliminary access check only against the corresponding RAT-specific sub-list. This segmentation enables the UE to quickly determine access authorization without unnecessarily checking against all CSG IDs, thereby preventing unauthorized access while accelerating handover preparation.
3Adaptability or versatility
If the allowed CSG list contains CSG IDs for multiple RATs without distinction, then the UE maintains comprehensive access control for all RATs, but the cell selection procedure becomes inefficient
Solution Approach 1:
The allowed CSG list is segmented into multiple RAT-specific sub-lists (e.g., one sub-list for LTE CSG IDs, another for WCDMA CSG IDs). Each sub-list maintains the access control functionality for its corresponding RAT. During cell selection or reselection, the UE selects the appropriate sub-list based on the current RAT context, enabling efficient comparison with only relevant CSG IDs while preserving comprehensive multi-RAT access control capabilities.
Solution Approach 2:
Different portions of the allowed CSG list (sub-lists) are assigned different qualities or characteristics based on RAT type. Each sub-list is optimized for its specific RAT context. The UE applies the appropriate sub-list locally based on the current RAT being evaluated, ensuring that the comparison operation is performed with data having the correct local quality (RAT-specific CSG IDs), thereby improving cell selection efficiency without sacrificing multi-RAT access control.
Data Source
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AI summary
A method for reducing the time spent for CSG identity comparison for a mobile device in a wireless communication system is disclosed. The method includes the steps of including RAT information in an Allowed CSG list and an Operator CSG List, wherein the Allowed CSG list and the Operator CSG List are stored in an elementary file of the mobile device and the RAT information indicates a plurality of RATs associated with a plurality of CSG identities listed in the allowed CSG list; controlling a non-access stratum (NAS) layer of the mobile device to read the allowed CSG list and the operator CSG List comprising the RAT information from the elementary file and pass the allowed CSG list and the operator CSG list comprising the RAT information to the AS layer; maintaining a plurality of sub-allowed CSG lists in an access stratum (AS) layer of the mobile device according to the plurality of RATs, wherein the number of the sub-allowed CSG lists corresponds to the number of the RATs; and comparing a CSG identity associated with a first RAT with the CSG identities listed in a first sub allowed CSG list corresponding to the first RAT.