CSG Cell Identification via Abbreviated Signalling
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Solution Overview
Problem
Current communication standards face inefficiencies in uniquely identifying closed subscriber group (CSG) cells within a macrocell, leading to increased signalling requirements and limited capacity for measurement reports due to the large size of cell global identifiers (CGI).
Innovation Solution
A method and apparatus that generate and transmit an abbreviated identifier for CSG cells in association with their physical layer identity and frequency, allowing unique identification between a mobile terminal and a macrocell, while maintaining a mapping for global uniqueness, thus reducing signalling overhead.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If cell global identifier (CGI) is used to uniquely identify CSG cells, then global uniqueness is achieved, but signalling overhead increases and measurement report capacity is limited
Solution Approach 1:
The identification system is segmented into two parts: a compact local identifier (5-10 bits) for CSG cell identification within the macrocell, and the full CGI (28 bits) stored in a mapping table. The mobile terminal transmits only the compact identifier in measurement reports, while the macrocell uses the mapping table to resolve the full CGI when needed, thus achieving global uniqueness with reduced signalling overhead.
Solution Approach 2:
A mapping table acts as an intermediary between the compact local identifier and the full CGI. This mapping table, maintained by the macrocell, enables translation from the space-efficient local identifier to the globally unique CGI when required for network operations, thereby resolving the contradiction between identification uniqueness and signalling efficiency.
2Measurement precision
If CGI is transmitted in measurement reports, then accurate CSG cell identification is achieved, but the quantity of other information that may be transmitted is limited
Solution Approach 1:
The essential identification function is extracted from the full CGI and implemented through a separate compact local identifier system. This extracted identifier contains sufficient information for accurate CSG cell identification within the macrocell context, allowing measurement reports to include this compact identifier along with other measurement information, thereby preserving information capacity while maintaining identification accuracy.
Solution Approach 2:
The identification information is segmented into a compact local identifier for transmission in measurement reports and the full CGI stored in a mapping table. This segmentation allows the measurement report to carry the essential identification data in a space-efficient manner while preserving the ability to access complete identification information when needed.
3Reliability
If cell change order includes full CGI, then target cell identification is unambiguous, but additional data transfer between macrocell and CSG cell is required
Solution Approach 1:
The cell change order message is segmented to include only the compact local identifier instead of the full CGI. Since the macrocell maintains a mapping table that associates local identifiers with full CGIs and other cell parameters, the compact identifier is sufficient for unambiguous target cell identification while minimizing data transfer volume in the cell change order message.
Solution Approach 2:
The mapping table serves as an intermediary that enables the macrocell to resolve the compact local identifier to the full CGI and other necessary cell parameters when processing the cell change order. This intermediary mechanism allows accurate target cell identification with reduced data transfer requirements.
Data Source
AI summary
A method, apparatus and computer program product are provided for identifying a closed subscriber group (CSG) cell to a macrocell in an efficient manner such that the identification of the CSG cell requires less signalling between the mobile terminal and the macrocell, thereby either reducing the overall signalling or providing increased capacity for additional measurement reporting by the mobile terminal. Additionally, a method, apparatus and computer program product are provided in which the CSG cell is identified in a more efficient manner in a cell change order, thereby similarly reduce the signalling requirements between a macrocell and a CSG cell.