Mesh RF Radiolocation with TDoA for Indoor and Urban Asset Tracking
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Solution Overview
Problem
Existing GPS and GNSS systems are ineffective in indoor and urban environments due to signal blocking and multipath propagation, leading to limited positional accuracy and coverage, and existing indoor positioning systems require extensive hardware infrastructure, which is costly and impractical for widespread adoption.
Innovation Solution
A mesh network of RF transponders using time difference of arrival (TDoA) and multilateration (MLAT) to locate and track RF transmitters, with a common reference clock for synchronization, enabling accurate location tracking of assets within a defined space.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If GPS/GNSS systems are used for location tracking, then positional accuracy can be achieved in open environments, but the system becomes ineffective in indoor and urban environments due to signal blocking
Solution Approach 1:
The patent introduces intermediate reference transmitters (pseudolites) deployed in indoor and urban environments that act as mediators between GPS satellites and receivers. These ground-based transmitters relay satellite signals locally, enabling positioning in environments where direct satellite signals are blocked by buildings or indoor structures.
Solution Approach 2:
The patent segments the monolithic GPS satellite constellation into a distributed network of ground-based reference transmitters. Instead of relying solely on distant satellites, the system divides positioning functionality across multiple local transmitters strategically placed in coverage areas, allowing signals to penetrate indoor and urban environments effectively.
2Measurement precision
If indoor positioning systems are implemented to achieve accurate location tracking in indoor environments, then positional accuracy improves, but extensive hardware infrastructure is required which increases cost and complexity
Solution Approach 1:
The patent makes existing GPS receivers multi-functional by enabling them to process signals from both satellite constellations and ground-based pseudolite transmitters. This universal compatibility allows the same hardware infrastructure to serve both traditional GPS applications and enhanced indoor/urban positioning without requiring separate specialized equipment.
Solution Approach 2:
The system enables receivers to self-adapt to different environments by automatically detecting and processing signals from available transmitters (satellites or ground-based). The infrastructure serves itself by utilizing existing GPS receiver technology and adding software capabilities rather than requiring completely new hardware systems.
3Adaptability or versatility
If signal blocking is addressed by deploying additional transmitters in urban canyons and indoor areas, then coverage improves, but the cost and complexity of the infrastructure increases
Solution Approach 1:
The patent merges satellite-based GPS infrastructure with ground-based transmitter networks into a unified positioning system. By combining these two approaches, the system achieves comprehensive coverage across all environments (outdoor, urban, indoor) while sharing common processing infrastructure and algorithms, thereby reducing overall implementation costs compared to maintaining separate systems.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Provides accurate location tracking of assets with sub-meter precision, even in challenging environments, without the need for extensive hardware infrastructure, enhancing applications in public safety, military security, retail, and supply chain logistics.
Implementation Method 1
radiolocation of RF transmitters using time difference of arrival or frequency difference of arrival (TDoA/FDoA) and multilateration (MLAT)
Implementation Method 2
radiolocation of RF transmitters using time difference of arrival or frequency difference of arrival (TDoA/FDoA)
Data Source
AI summary
A method of determining a reference clock in a mesh network includes receiving multiple signals, correlating the multiple signals with a local signal generated by the first node to determine a coarse set of time differences, refining the coarse set of time differences using a phase of a carrier signal of the multiple signals to produce a refined set of time differences, and using the refined set of time differences to define a reference clock.