Virtual Active Set Segmentation for Wireless Mobility
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Solution Overview
Problem
In wireless communication networks, especially those incorporating femto access points and virtual active sets, there are challenges with accurate frequency quality estimation due to inclusion of macro and HNB cells in the same virtual active set, leading to false handover decisions and reduced mobility efficiency.
Innovation Solution
The solution involves maintaining separate virtual active sets for different types of access points, such as HNBs and macro cells, and using dedicated cell lists to configure these sets, allowing for more precise frequency quality estimation and improved handover decisions by focusing on the quality of individual HNB cells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If macro cells and HNB cells are included in the same virtual active set for frequency quality estimation, then the measurement process is simplified, but the frequency quality estimation accuracy deteriorates due to interference between different cell types
Solution Approach 1:
The patent segments the virtual active set into separate components: one for macro cells and another for HNB cells. This segmentation allows independent quality estimation for each cell type, preventing interference between them while maintaining separate measurement processes for macro and femto cell evaluations.
Solution Approach 2:
The patent extracts HNB cells from the traditional virtual active set structure, creating a separate evaluation mechanism. By taking out HNB-specific measurements and evaluations from the macro cell-dominated virtual active set, the system eliminates interference and enables accurate quality estimation for both cell types independently.
2Ease of operation
If a single virtual active set is used for both macro cells and HNB cells, then the handover decision process is simplified, but false handover decisions occur due to inaccurate quality estimates
Solution Approach 1:
The patent segments the handover decision process into separate evaluation streams: one for macro cells and another for HNB cells. Each cell type is evaluated independently using its own quality metrics and thresholds, ensuring that handover decisions are based on accurate, interference-free quality estimates for the specific cell type being considered.
Solution Approach 2:
The patent introduces an intermediary evaluation layer that processes HNB-specific measurements separately before integrating them into the overall handover decision. This intermediary mechanism ensures that HNB quality estimates do not interfere with macro cell evaluations, while still enabling coordinated handover decisions across both cell types.
3Area of stationary object
If macro cells dominate the virtual active set measurements, then the measurement coverage is comprehensive, but HNB quality estimates are skewed by macro cell signal dominance
Solution Approach 1:
The patent segments the measurement process to create separate measurement sets: one dedicated to macro cells and another dedicated to HNB cells. This segmentation ensures that HNB measurements are not dominated by macro cell signals, as each cell type is measured and evaluated independently with appropriate thresholds and criteria.
Solution Approach 2:
The patent applies local quality evaluation by setting cell-type-specific quality thresholds and measurement criteria. Instead of using a single uniform threshold for all cells, the system applies localized quality standards appropriate for each cell type, ensuring that HNB quality estimates reflect actual HNB signal conditions rather than being skewed by macro cell dominance.
Data Source
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AI summary
To facilitate inbound mobility for an access terminal, different virtual active sets are employed for different types of access points or cells (e.g., HNBs versus macro cells). In addition, different lists of permitted cells are maintained for these different types of access points or cells. Also, a frequency quality estimate for inter-frequency event triggering may be based on measurement of a single cell present in a virtual active set (e.g., a dedicated HNB virtual active set).