Femto Cell Synchronization Using Forward Link Receiver
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Solution Overview
Problem
Femto cells in wireless communication systems face challenges in synchronization with macro cells, particularly in indoor installations where GPS signals are weak, leading to slow initial timing acquisition and restricted physical placement due to the need for GPS receivers.
Innovation Solution
Incorporating a forward link receiver into femto cells allows for synchronization with macro cells using a superior antenna gain, enabling connection and clock derivation, even in weak signal conditions, and providing flexibility in placement without the need for a full mobile station modem.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If GPS receiver is used for synchronization, then timing acquisition accuracy is improved, but device complexity and cost increase
Solution Approach 1:
The patent extracts the essential synchronization function from the complete GPS receiver system. Instead of implementing a full GPS receiver with all its complexity, the invention uses only the forward link receiver component to acquire timing information from macro cell transmissions, thereby achieving timing synchronization without the need for GPS hardware while significantly reducing device complexity
Solution Approach 2:
The patent copies the timing synchronization function from GPS-based systems by using the forward link receiver to capture and process macro cell signals. The forward link receiver replicates the timing acquisition capability of GPS receivers by extracting timing information from downlink pilot signals, achieving the same synchronization effect through a different, simpler mechanism
2Reliability
If GPS receiver is used for synchronization, then timing acquisition reliability is improved, but cost increases
Solution Approach 1:
The patent replaces expensive GPS receiver hardware with a more economical forward link receiver that can achieve the same timing synchronization function. The forward link receiver is a standard component in mobile stations, making it a cheaper alternative to dedicated GPS receivers while maintaining reliability in timing acquisition through efficient signal processing of macro cell downlink signals
3Device complexity
If forward link receiver is used for synchronization, then device complexity is reduced, but timing acquisition speed may worsen
Solution Approach 1:
The patent implements preliminary action by having the forward link receiver continuously monitor and track macro cell downlink signals before synchronization is actually needed. The receiver maintains timing information and signal characteristics in advance, so when synchronization is required, the femto cell can quickly acquire timing information without performing a complete signal search, thereby maintaining fast timing acquisition speed despite using a simpler receiver
4Adaptability or versatility
If GPS receiver is required for synchronization, then placement flexibility is restricted, but if forward link receiver is used, then placement flexibility is improved
Solution Approach 1:
The patent applies universality by using the forward link receiver, which is a multi-functional component already present in mobile stations for various communication functions. This single component serves multiple purposes including signal reception, demodulation, and timing synchronization, eliminating the need for dedicated GPS receivers and enabling flexible indoor placement while maintaining synchronization reliability through robust signal processing
Data Source
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AI summary
A system, a method and computer product for synchronizing of a femto cell with a macro cell, the method comprising: placing a forward link receiver into the femto cell; receiving by a micro cellular network the femto cell transmission timing; and synchronizing the femto cell transmission timing with the macro cellular network transmission timing in reliance on the forward link receiver signal. Further, a system, a method and computer product for allocating pilot phases to femto cells, the method comprising: creating at least as many new potential pilot phases for femto cells as there are for macro cells; and allowing a mobile device on a macro cell to search and find a femto cell pilot without explicitly listing femto pilot phases in the neighbor list.