Antenna Cluster Timing Offset Calibration for Indoor RF Tracking
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Solution Overview
Problem
Conventional RF-based location-finding systems face inaccuracies in indoor environments due to time synchronization errors, which affect the precision of multilateration/trilateration methods used in cellular networks, failing to meet the stringent location requirements of Real Time Locating Service (RTLS) and Location Based Services (LBS).
Innovation Solution
The implementation of a system that uses partially synchronized receivers and transmitters in clusters, employing software-defined radio and digital signal processing technologies, allowing for precise time synchronization within clusters while relaxing synchronization requirements between clusters, and utilizing narrow bandwidth ranging signals to enhance location accuracy in RF-based tracking and locating systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If complete and precise time synchronization is implemented across all antennas in cellular networks, then location accuracy is improved, but system complexity and cost increase significantly
Solution Approach 1:
The patent divides the cellular network into multiple synchronized antenna clusters, where each cluster maintains internal time synchronization but clusters themselves operate with relaxed synchronization requirements. This segmentation allows location accuracy to be improved within each cluster while avoiding the need for complete network-wide synchronization, thereby reducing overall system complexity.
Solution Approach 2:
The patent implements strict time synchronization only within local antenna clusters rather than across the entire network. Each cluster achieves the synchronization quality necessary for accurate location determination, while the overall system maintains flexibility and reduced complexity by not requiring uniform synchronization across all antennas.
2Measurement precision
If time synchronization accuracy is increased to meet RTLS requirements, then location accuracy is improved, but ranging signal bandwidth requirements increase
Solution Approach 1:
The patent applies partial synchronization within antenna clusters rather than complete synchronization across the entire network. This partial action approach provides sufficient time synchronization accuracy for location determination without requiring the excessive bandwidth that would be needed for full network-wide synchronization at RTLS accuracy levels.
3Area of stationary object
If multilateration/trilateration methods are used for location determination, then location coverage is improved, but time synchronization error impact increases
Solution Approach 1:
The patent segments the multilateration process into cluster-level operations, where time synchronization is maintained within each antenna cluster. This allows multilateration to provide broad location coverage across multiple clusters while the synchronization segmentation minimizes error propagation, as each cluster operates with its own synchronized time reference.
Data Source
AI summary
Systems and methods for determining a timing offset of a plurality of emitter antennas in a wireless network. The methods include deploying a network synchronization calibration unit at a location within receiving range of a plurality of direct path reference signals transmitted by the plurality of emitter antennas. The synchronization calibration unit receives the plurality of direct path reference signals and one or more reflected reference signals, which are then separated from one another to identify the direct path reference signals when a signal strength of one direct path reference signal is less than a signal strength of a reflected reference signal. A set of data is collected from the reflected reference signals that is indicative of the timing offset and that set of data is analyzed to estimate the timing offset.