Hybrid Cell Access Mode Determination in LTE
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Solution Overview
Problem
In wireless communication systems, user equipment (UE) cannot accurately determine the access mode of a hybrid cell, leading to issues where CSG members may not receive services despite being part of the Closed Subscriber Group (CSG), due to the limitations of using only a CSG indicator for classification.
Innovation Solution
The UE checks for the existence of a CSG identity in addition to the CSG indicator to distinguish hybrid cells from other types of cells, allowing it to recognize and access hybrid cells as CSG cells if it is a member, thereby providing priority services during access or handover.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If only a CSG indicator is used to determine cell access mode, then the determination process is simple, but hybrid cells cannot be accurately distinguished from other cell types
Solution Approach 1:
The patent segments the cell identification process into multiple stages: first checking the CSG indicator to quickly eliminate non-CSG cells, then checking for CSG identity existence to identify hybrid cells. This segmentation allows the system to maintain simplicity for clear cases while adding precision for ambiguous hybrid cell scenarios.
Solution Approach 2:
The patent adds another dimension to cell identification by introducing the CSG identity existence check as a secondary criterion beyond the CSG indicator. This dimensional expansion enables the system to distinguish hybrid cells (which have CSG indicator = false but CSG identity exists) from both open cells and closed CSG cells.
2Measurement precision
If the UE checks for CSG identity existence in addition to CSG indicator, then hybrid cells can be accurately identified, but the determination process becomes more complex
Solution Approach 1:
The patent applies preliminary action by first checking the CSG indicator before checking for CSG identity existence. This preliminary check allows the UE to quickly determine access mode for non-hybrid cells without performing the more complex CSG identity verification, thereby reducing overall processing complexity while maintaining identification accuracy.
Solution Approach 2:
The patent applies local quality by making the CSG identity check conditional - it is only performed when the CSG indicator suggests ambiguity. This selective application of the additional check ensures precision is applied locally where needed (potentially hybrid cells) rather than universally, reducing unnecessary processing complexity.
3Reliability
If hybrid cells are not accurately distinguished, then CSG members may be denied service, but implementing accurate distinction requires additional checking steps
Solution Approach 1:
The patent performs preliminary checking of the CSG indicator to quickly identify cells that are definitely not hybrid cells. This allows CSG members to rapidly access clearly-marked CSG cells without undergoing the full verification process, reducing access time while maintaining reliability for hybrid cell identification through the subsequent CSG identity check.
Data Source
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AI summary
The present invention relates to a wireless communication system and a UE providing wireless communication services in an evolved UMTS or a LTE system, and to a method of determining the operation mode of a base station, that is, the access mode of a cell, based on which UE's connection is allowed by the base station or not. It is an object of the present invention to provide a process of determining the access mode of a cell by checking a closed subscriber group indicator (CSG) and, if the CSG indicator indicates that the cell is a CSG cell allowing the access only to the UEs of a closed subscriber group, checking a CSG identity to determine whether the UE is a member of the group.