Mobile TDOA Geolocation Using Sensor Relocation
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Solution Overview
Problem
Current geolocation techniques for mobile wireless stations, such as the time difference of arrival (TDOA) method, require a large number of sensors to achieve accurate position location estimates, especially in complex terrains, which is impractical and inefficient.
Innovation Solution
The Mobile-TDOA (M-TDOA) technique uses a minimum of two sensors, allowing them to relocate and acquire measurements over time, forming algebraic equations with enough degrees of freedom to accurately geolocate emitters, effectively creating virtual sensors and reducing the need for multiple sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional TDOA method uses a large number of sensors to achieve accurate position location estimates, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent applies the dynamics principle by transitioning from static sensors to mobile sensors that can change positions over time. The mobile sensors acquire measurements at multiple different position locations, creating temporal and spatial diversity that replaces the need for numerous simultaneous sensors. This dynamic approach allows the system to achieve equivalent measurement precision with fewer sensors by utilizing measurements taken at different times and positions.
Solution Approach 2:
The patent introduces the time dimension to the traditional spatial measurement approach. Instead of only using spatial diversity (multiple sensors at different positions simultaneously), the system adds temporal diversity by having sensors move to different positions at different times. This transformation from purely spatial to spatio-temporal measurements resolves the contradiction by providing sufficient geometric diversity through time-varying positions rather than through numerous concurrent sensors.
2Measurement precision
If traditional TDOA method requires at least three or four sensors for basic location estimation, then measurement precision is improved, but ease of operation deteriorates due to the large number of sensors needed
Solution Approach 1:
By making sensors mobile rather than static, the system reduces the number of sensors needed from three or four to just two. The mobile sensors can be relocated to create the necessary geometric baselines for accurate positioning, eliminating the need to deploy and coordinate multiple stationary sensors. This dynamic repositioning capability dramatically simplifies the deployment and operation of the geolocation system.
3Measurement precision
If traditional TDOA method uses fixed sensors at multiple positions simultaneously, then measurement precision is improved, but loss of time increases due to the need for simultaneous measurements
Solution Approach 1:
The system employs periodic measurement acquisition where mobile sensors sequentially visit different position locations to collect measurements. Instead of requiring all sensors to be present simultaneously, the mobile sensors periodically return to key positions to acquire the necessary TDOA measurements. This periodic sampling in time replaces the simultaneous spatial sampling, achieving equivalent positioning accuracy without requiring all measurements to occur at the same moment.
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
M-TDOA achieves accurate geolocation with fewer sensors than traditional methods, improving efficiency and flexibility by allowing sensors to move and acquire additional independent measurements, reducing the number of sensors required for precise emitter location estimation.
Implementation Method 1
calculate the difference in time of arrival (TOA) of a transmitted signal from a Wireless Station to a number of sensors
Data Source
AI summary
The present invention provides a method by which the position of a wireless emitter can be estimated by using a minimum of two wireless transceiver devices. The invention relies on physically moving the wireless transceiver devices to new position locations in order to obtain multiple time difference of arrival measurements. The time difference of arrival measurements can then be combined to derive estimates for the position of the emitter. At least one of the two wireless transceiver devices needs to be mobile with the other one fixed. Using this invention, any proportion of mobile and fixed transceiver devices can be used to derive the position of a wireless emitter. The wireless emitter to be located is not assumed to provide any information about itself to the wireless transceivers used for estimating its position location. The method is referred here as a Mobile-TDOA method or M-TDOA. The method is very general, very flexible and can be very inexpensive due to the minimum amount of hardware resources required.