CSG Cell Discovery via Physical Cell Identity Filtering
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Solution Overview
Problem
In cellular communications networks, especially in environments with densely deployed femtocells, the search for allowed Closed Subscriber Group (CSG) cells by user equipment (UE) is resource-intensive, leading to excessive battery consumption and potential reduction in battery lifetime.
Innovation Solution
Providing the UE with accurate and up-to-date knowledge of the physical cell identities of its allowed CSG cells, allowing it to swiftly dismiss non-matching cells and only retrieve CSG IDs for matching identities, thereby reducing resource consumption during the search process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the UE performs exhaustive search for allowed CSG cells by retrieving CSG IDs from all detected cells, then the UE can ensure complete and accurate CSG cell discovery, but the battery consumption increases significantly and battery lifetime is reduced
Solution Approach 1:
The network provides the UE with preliminary information about allowed CSG cell identities (such as physical cell identities or global cell identities) before the UE performs the search. This preliminary action allows the UE to filter and identify only the relevant cells from the detected set, avoiding the need to retrieve CSG IDs from all cells, thus reducing battery consumption while maintaining discovery accuracy
Solution Approach 2:
The invention extracts only the necessary identification information (cell identities) from the network and provides it to the UE. The UE then uses this extracted information to selectively identify allowed CSG cells without performing exhaustive CSG ID retrieval from all detected cells, thereby reducing energy consumption while preserving measurement precision
2Reliability
If the UE retrieves CSG IDs from all detected cells to ensure accurate CSG cell identification, then the reliability of CSG cell discovery is improved, but the time consumption and resource usage increase
Solution Approach 1:
The network performs preliminary preparation by providing the UE with a list of allowed CSG cell identities before the search process. This allows the UE to quickly match detected cells against the pre-provided identities, ensuring reliable identification without the time-consuming process of retrieving and checking CSG IDs from all detected cells
Solution Approach 2:
The cell identification process is segmented into two stages: first, the UE detects all cells and compares their identities against the pre-provided allowed CSG cell identities list; second, only the matching cells undergo further CSG ID verification. This segmentation reduces the overall time consumption while maintaining identification reliability
3Productivity
If the network provides detailed CSG cell information to all UEs, then the UE can efficiently identify allowed CSG cells, but the network signaling overhead and complexity increase
Solution Approach 1:
The network extracts and provides only the essential identification information (physical cell identities or global cell identities of allowed CSG cells) to the UE, rather than transmitting complete CSG cell details. This extracted information is sufficient for the UE to efficiently identify allowed CSG cells while minimizing network signaling overhead and complexity
Solution Approach 2:
The invention changes the parameter being transmitted from complete CSG cell information to a simplified set of identification parameters (cell identities). This parameter change maintains the UE's ability to efficiently discover allowed CSG cells while significantly reducing network signaling complexity and overhead
Data Source
AI summary
The present invention relates to methods and arrangements that make CSG cell discovery more resource efficient. That is achieved by providing the UE with accurate and up-to-date knowledge of the physical cell identity (identities) of its allowed CSG cell(s). Accurate knowledge of the PCI of an allowed CSG cell greatly simplifies the search/discovery procedure for this CSG cell, in particular the procedure can be made much more resource efficient and UE battery lifetime can be prolonged.