Femtocell Location Determination via Macrocell Relay
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Solution Overview
Problem
Femtocell base stations in deep indoor locations struggle to determine their geographical location accurately due to difficulty in acquiring GPS signals, and existing solutions like external GPS antennas or radio detection of neighboring macrocells are either impractical or provide limited accuracy.
Innovation Solution
A method where femtocells that can acquire GPS signals share their location information with neighboring femtocells that cannot, allowing them to estimate their own location through a process of location cascading and interpolation, ensuring accurate geographical determination and authorization for transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a femtocell base station uses an internal GPS receiver to determine its location, then the device complexity is reduced and ease of operation is improved, but the measurement precision of location determination deteriorates in deep indoor locations where GPS signals cannot be acquired
Solution Approach 1:
The patent introduces macrocell base stations as intermediary entities that can determine their locations using GPS and share this information with femtocell base stations. The macrocell acts as a mediator that bridges the gap between satellites and indoor femtocells, allowing location determination without direct GPS access at the femtocell site.
Solution Approach 2:
The patent replaces the direct GPS reception mechanism (electromagnetic signal reception from satellites) with an indirect information transfer mechanism through the cellular network. Instead of relying on physical GPS signal propagation that penetrates buildings, the system uses network-based message passing to convey location information.
2Measurement precision
If a femtocell base station uses external GPS antenna to improve location determination accuracy, then the measurement precision is improved, but the device complexity and ease of installation deteriorate
Solution Approach 1:
The patent extracts the GPS reception function from the femtocell base station itself and relocates it to macrocell base stations. This separates the location determination function from the femtocell deployment, allowing femtocells to be installed anywhere without GPS antenna requirements while macrocells handle the GPS reception centrally.
3Ease of operation
If a femtocell base station uses radio detection of neighboring macrocells to determine location, then the ease of operation is improved, but the measurement precision and reliability of location determination deteriorate
Solution Approach 1:
The patent merges the location determination approaches by having the system first attempt direct GPS reception at the femtocell, and if that fails, automatically fall back to the macrocell-based indirect determination method. This combination ensures both methods can be used depending on conditions, providing both ease of operation and acceptable precision.
Data Source
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AI summary
A method is provided of authorising a small cell base station to transmit comprising the small cell base station: detecting a neighbour base station; sending to the neighbour base station a request for information of the location of the neighbour base station; receiving said information; determining its own location from said information; checking whether the determined location is within a given area in which the small cell base station is permitted to transmit; and dependent upon the result of the check, authorising the small cell base station to transmit.