Hybrid PNT Time Synchronization Using Signals of Opportunity
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Solution Overview
Problem
Terrestrial Positioning, Navigation, and Timing (PNT) systems face challenges in providing adequate coverage without increasing cost due to the need for multiple transmitters, and issues with synchronization errors and near-far problems in using signals of opportunity (SoOPs) limit their accuracy.
Innovation Solution
A hybrid PNT system combining purpose-built terrestrial PNT systems with SoOPs, synchronized to a common time scale like UTC, using listening devices to distribute timing synchronization information and mitigate near-far issues by leveraging multiple SoOP systems and interference cancellation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If more transmitters are deployed to provide adequate beacon signal coverage, then coverage and location capabilities are improved, but system cost increases
Solution Approach 1:
The patent combines purpose-built terrestrial PNT transmitters with existing SoOP transmitters (cellular, WiFi, Bluetooth) into a hybrid system. This merging allows the system to leverage existing transmitter infrastructure while supplementing it with dedicated PNT transmitters, thereby achieving adequate coverage without proportionally increasing cost.
Solution Approach 2:
The patent makes existing transmitters (cellular base stations, WiFi access points, Bluetooth devices) serve dual purposes: their original communication functions plus PNT functions. By enabling these transmitters to provide both data communication and positioning/navigation/timing services, the system reduces the need for dedicated transmitters only for PNT.
2Device complexity
If signals of opportunity (SoOPs) are used for positioning, then system cost is reduced, but synchronization errors and near-far problems limit accuracy
Solution Approach 1:
The patent introduces listening devices as intermediary components that receive signals from both SoOP transmitters and purpose-built transmitters. These listening devices perform time synchronization and position calculations, acting as mediators that enable accurate positioning despite the asynchronous nature of SoOP signals.
Solution Approach 2:
The system uses listening devices to continuously monitor signal timing and position information, providing feedback to adjust synchronization parameters and calculate accurate positions. This feedback mechanism compensates for synchronization errors and near-far problems by adaptively correcting measurements based on observed signal characteristics.
3Device complexity
If fewer transmitters are used to reduce cost, then system cost decreases, but beacon signal coverage becomes inadequate
Solution Approach 1:
The patent merges the coverage areas of multiple transmitter types (cellular, WiFi, Bluetooth, and purpose-built PNT transmitters) to create a comprehensive coverage map. By combining these different transmitter networks, the system achieves extensive geographic coverage while using a relatively small number of dedicated PNT transmitters.
Solution Approach 2:
The patent transitions from a two-dimensional transmitter deployment problem to a multi-dimensional solution by utilizing signals from multiple sources at different ranges and characteristics. By incorporating SoOP transmitters at various distances and purpose-built transmitters at strategic locations, the system achieves three-dimensional coverage optimization.
Data Source
AI summary
A method includes a mobile device receiving a plurality of first signals from one or more first transmitters in a network. Each first signal has first data including an associated time that is non-synchronized to the time of another first signal of the plurality of first signals. One or more processors synchronizes the associated time of each first signal to a common time scale. One or more processors determines a position of the mobile device using a common time scale of the plurality of first signals.