Cell Grouping for UE Measurement in Small Cell Networks
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Solution Overview
Problem
In communication systems with a large number of small cells, user equipment (UE) faces challenges in efficiently measuring cells for re-selection and handover due to the small coverage range and high mobility, leading to potential failures in cell re-selection and handover processes.
Innovation Solution
The communication system groups cells into groups, allowing user equipment to select and measure cells within specific groups for re-selection and handover, limiting measurements to cells within the selected group, even at high speeds, thereby improving mobility performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If cells are measured for re-selection and handover in a communication system with a large number of small cells, then the coverage and connectivity are improved, but the measurement time and processing load increase significantly
Solution Approach 1:
The patent divides the large number of cells into multiple groups. The user equipment (UE) is configured to measure and evaluate cells within the same group as the serving cell, rather than measuring all cells system-wide. This segmentation reduces the measurement scope from N cells to a subset of cells within the group, significantly decreasing measurement time and processing load while maintaining reliable cell re-selection and handover functionality.
2Reliability
If cells are measured for re-selection and handover in a communication system with a large number of small cells, then the coverage and connectivity are improved, but the processing load increases significantly
Solution Approach 1:
The patent segments the cell measurement process by introducing group identifiers. The UE only processes cells that share the same group identifier as the serving cell, filtering out cells from other groups. This reduces the processing load from evaluating all N cells to evaluating only the subset of cells within the same group, making the system manageable even with a large total number of small cells.
3Area of stationary object
If the coverage range of each cell is reduced to create more small cells, then the network capacity and coverage are improved, but the mobility performance and handover reliability deteriorate
Solution Approach 1:
The patent introduces cell grouping as a segmentation mechanism that works at the logical layer. Even though small cells have limited physical coverage ranges, the grouping allows the UE to maintain a focused measurement set within the same group, ensuring that handover decisions can be made reliably based on cells that are logically associated with the serving cell, thereby compensating for the small physical coverage ranges.
Solution Approach 2:
The network pre-configures cell groups and provides group identifier information to the UE before handover or re-selection is needed. This preliminary action allows the UE to have advance knowledge of which cells to monitor, reducing the need for extensive real-time measurements and improving mobility performance despite the small coverage ranges of individual cells.
Data Source
AI summary
A UE in an idle state selects any of a group A, to which a cell of which coverage its own device is in, belongs and a group different from the group A, for example, a group B, and then measures cells belonging to the selected group for selecting a cell being a re-selection destination. A UE in a connected state selects any of the group B to which a cell connected with the UE belongs and a group different from the group B, for example, the group A, and measures cells belonging to the selected group for handover.