CSG Cell Handover Filtering via Serving Base Station Intermediary
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Solution Overview
Problem
Current closed subscriber group (CSG) base stations face challenges with high processing loads due to handling non-authorized handover requests and inefficient user authorization, leading to performance issues and increased operational costs.
Innovation Solution
Implementing a system where radio terminals are informed not to report signal quality measurements from CSG base stations by default, with authorized terminals receiving specific instructions to include these measurements in their reports, and using a central node to manage and filter CSG cell authorization lists to reduce unnecessary signaling and processing loads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If CSG base stations handle all handover requests from radio terminals, then handover service coverage is improved, but processing load on CSG base stations increases significantly
Solution Approach 1:
The serving base station acts as an intermediary that filters handover requests before they reach the CSG base station. It determines whether radio terminals are authorized to access the CSG cell and only forwards authorized handover requests, thereby reducing the processing load on the CSG base station while maintaining comprehensive handover service coverage.
2Adaptability or versatility
If CSG base stations process all handover requests including non-authorized terminals, then handover capability is improved, but handover performance deteriorates due to rejected requests
Solution Approach 1:
The serving base station performs preliminary authorization checking before forwarding handover requests to the CSG base station. By determining in advance whether a radio terminal is authorized to access the CSG cell and filtering out non-authorized requests, the system maintains full handover capability while improving handover performance by eliminating rejected requests.
3Measurement precision
If all radio terminals report signal quality measurements from CSG base stations, then measurement accuracy is improved, but signaling load increases
Solution Approach 1:
The system applies different measurement reporting behaviors to different radio terminals based on their authorization status. Authorized terminals report signal quality measurements from CSG base stations, while non-authorized terminals do not report such measurements. This differentiated approach maintains measurement accuracy for authorized users while reducing overall signaling load.
4Adaptability or versatility
If CSG base stations accept handover requests from all radio terminals, then access service coverage is improved, but user authorization management becomes complex
Solution Approach 1:
The serving base station serves as an intermediary that manages user authorization centrally. It maintains authorization information for radio terminals and determines whether each terminal is authorized to access the CSG cell, thereby simplifying authorization management at the CSG base station while maintaining comprehensive access service coverage.
Data Source
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AI summary
A radio terminal connection may be handed over from a serving base station associated with a serving cell to a closed subscriber group (CSG) cell served by a CSG base station in which only radio terminals belonging to the CSG are permitted to access and receive service from the CSG cell. Radio terminals in the serving cell are generally informed not to report to the serving base station signal quality measurements of signals transmitted by CSG base stations. But if a radio terminal in the serving cell is authorized to access and receive service from the CSG cell, then that radio terminal is instructed to report to the serving base station signal quality measurements of signals transmitted by the CSG base station. Based on that report, the connection may be handed over to the CSG base station. A central node provides a CSG authorization list identifying CSG authorized radio terminals to the serving base station when a listed CSG cell is a neighboring cell which the radio terminal is authorized to access.