Cell Reselection in Mixed Macrocell and CSG Environments
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Solution Overview
Problem
Conventional cell reselection methods fail to appropriately select Closed Subscriber Group (CSG) cells in mixed macrocell and CSG environments, leading to inefficient battery energy consumption and potential interference due to strict signal quality criteria.
Innovation Solution
A user apparatus with a measurement unit, cell search unit, and cell reselection unit that measures signal quality at predefined cycles and reselects cells based on specific criteria, including a predefined reselection duration and hysteresis threshold, to identify and switch to CSG cells when their signal quality exceeds that of the resident macrocell by a predefined threshold.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional cell reselection criteria are used in mixed macrocell and CSG environments, then cell reselection can be performed, but inappropriate cell selection occurs leading to inefficient battery energy consumption and potential interference
Solution Approach 1:
The patent applies local quality by implementing different cell reselection criteria for different cell types. CSG cells use a specific reselection criterion (Qn > Qs + Qhyst) that differs from conventional macrocell reselection, allowing appropriate selection behavior tailored to each cell type's characteristics and access restrictions
Solution Approach 2:
The patent performs preliminary actions by measuring signal quality of neighbor cells at predefined cycles even before reselection is triggered. This allows the system to have advance knowledge of available CSG cells and their signal qualities, enabling faster and more accurate reselection decisions when needed
2Object-affected harmful factors
If strict signal quality criteria are applied for cell reselection, then interference can be minimized, but CSG cells cannot be appropriately selected in mixed environments
Solution Approach 1:
The patent changes the reselection parameter by introducing a specific criterion for CSG cells (Qn > Qs + Qhyst) that modifies the conventional reselection approach. This parameter change allows the system to appropriately select CSG cells while maintaining interference minimization through the hysteresis component
3Loss of time
If frequent broadcast information reception is performed to enable fast cell reselection, then cell reselection latency is reduced, but battery energy consumption increases
Solution Approach 1:
The patent implements periodic action by measuring signal quality of neighbor cells at predefined cycles rather than continuously. This periodic measurement approach balances the need for timely reselection information with battery energy conservation, reducing unnecessary measurements while maintaining acceptable reselection latency
Data Source
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AI summary
A disclosed user apparatus is for use in a mobile communication system including a macrocell and a closed cell wherein unspecified users are allowed to access the macrocell and specified users are allowed to access the closed cell. The user apparatus includes a measurement unit configured to measure quality of a signal provided from a camped cell in an idle state at a predefined cycle, a cell search unit configured to measure quality of a signal provided from a neighbour cell at a predefined cell search cycle, and a cell reselection unit configured to reselect a cell depending on the cell search result. A frequency of the macrocell is at least partially identical to a frequency of the closed cell. If the user apparatus resides in the macrocell and a predefined reselection criterion is satisfied, the closed cell adjacent to the camped cell is reselected as a standby cell. The predefined reselection criterion corresponds to a state where the quality of the signal provided from the closed cell has been higher than or equal to the quality of the signal provided from the camped cell by a predefined threshold for more than a predefined reselection duration.