Ad-Hoc Location Tracking Using Virtual Coplanar Reference Routers
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Solution Overview
Problem
Existing wireless communication systems, particularly in ad-hoc multi-hopping networks, face challenges in accurately determining the location of mobile nodes in environments with limited satellite visibility, such as underground tunnels, buildings, and urban areas, where GPS is unreliable.
Innovation Solution
A system and method using ad-hoc wireless multi-hopping networks with reference routers deployed in a building to calculate the two-dimensional location of mobile nodes based on Time Of Arrival (TOA) measurements from at least three coplanar reference devices, allowing for accurate floor determination even in scenarios with limited coplanar references.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If GPS technique is used for location determination, then high accuracy can be achieved in open environments, but it becomes unreliable in environments with limited satellite visibility such as underground tunnels, inside buildings, and urban canyons
Solution Approach 1:
The patent introduces reference routers as intermediary devices deployed within the target environment (buildings, tunnels) to mediate location determination. These reference routers receive signals from satellites and relay timing information to mobile nodes, enabling location determination in environments where direct satellite visibility is limited. This intermediary approach allows the system to overcome the limitation of GPS in enclosed spaces while maintaining accuracy through local reference points.
2Area of stationary object
If ad-hoc multi-hopping networks are deployed to expand coverage area, then network reachability improves, but location determination becomes more complex in temporary networks without permanent infrastructure
Solution Approach 1:
The patent makes reference routers multi-functional devices that simultaneously perform routing functions (forwarding packets in the ad-hoc network) and location determination functions (providing timing references for TOA calculations). This universality eliminates the need for separate infrastructure for location tracking, reducing overall system complexity while maintaining the ability to determine locations in expanded coverage areas.
Solution Approach 2:
The system enables mobile nodes to self-determine their locations by receiving timing information from reference routers and performing TOA calculations autonomously. The mobile nodes independently compute their positions without requiring centralized location management, reducing the complexity of location detection in temporary ad-hoc networks while supporting expanded coverage areas.
3Loss of information
If three-dimensional location calculation is performed using reference devices on different floors, then complete spatial information is obtained, but computational complexity increases and altitude measurement requirements are introduced
Solution Approach 1:
The patent extracts the vertical dimension (altitude) from the location calculation process by confining mobile nodes to operate within a single floor plane. This extraction eliminates the need for three-dimensional calculations and altitude measurements, reducing computational complexity while preserving complete two-dimensional spatial information within each floor, thereby preventing information loss in the operational context.
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
Enables accurate and reliable location tracking of personnel in emergency situations, such as firefighting, by providing real-time location information and improving connectivity within the incident area, even in harsh conditions, with reduced computational complexity and no need for altitude measurements.
Implementation Method 1
The two-dimensional location of the mobile node is calculated based on lateral distances calculated from time of arrival (TOA) measurements
Data Source
AI summary
A method and apparatus for calculating a location of a device is provided. A likelihood of the device being located at a particular location point or a particular location floor is determined using a likelihood calculation at each of a plurality of locations. The location point or location floor is then identified as that location having an associated highest likelihood calculation. The likelihood calculation includes calculating a distance from the device to each of a plurality of reference routers including one or more virtual coplanar reference routers, wherein each of the one or more virtual coplanar reference routers comprise a projection of a non-coplanar reference router onto the floor.