Dual Network Location Tracking Using Round Trip Delay
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Solution Overview
Problem
Existing location and tracking systems often provide position accuracy of only a few meters, which is insufficient for applications requiring precision such as associating individuals or assets within close proximity, particularly in environments like hospitals, hotels, and manufacturing facilities, where room-level accuracy is necessary to ensure proximity rather than exact location.
Innovation Solution
The system employs first and second networks with tags placed on assets (mobile tags) and zones (zone tags) to determine position location coordinates using round trip delay measurements, allowing for accurate proximity detection and alignment of frame timing to enhance positioning accuracy to less than one meter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If Wi-Fi or Bluetooth networks are used for location tracking, then the system complexity is low and ease of operation is good, but the position accuracy is only a few meters which is insufficient for room-level precision requirements
Solution Approach 1:
The system segments the positioning function into two parts: a first network (Wi-Fi/Bluetooth) providing approximate location coordinates, and a second network (time synchronization network) providing precise distance measurements via round trip delay. This segmentation allows each network to operate at its optimal complexity level while achieving high overall precision through coordinate transformation and fusion at the server level.
Solution Approach 2:
The position location server acts as an intermediary that receives data from both networks, performs coordinate transformation to align reference frames, and fuses the approximate coordinates with precise distance measurements to compute final high-accuracy positions. This intermediary handles the complexity of multi-network integration, keeping individual network components simple.
2Measurement precision
If round trip delay measurements are implemented between mobile tags and zone tags, then position accuracy improves to less than one meter, but the device complexity and measurement infrastructure requirements increase
Solution Approach 1:
Tags in the system serve multiple functions: they act as both mobile tags for tracking moving assets and zone tags for defining stationary zones. The same hardware platform performs both mobile tracking and zone definition, eliminating the need for separate infrastructure components and simplifying deployment while enabling precise round trip delay measurements.
Solution Approach 2:
The system uses existing network infrastructure (Wi-Fi access points, mobile devices) to provide the timing synchronization and measurement capabilities needed for precise positioning. Rather than requiring dedicated expensive hardware, the system leverages universally available components that already possess the necessary processing and communication capabilities.
3Measurement precision
If frame timing alignment is performed between zone tags within a few microseconds, then the measurement precision for distance calculation improves, but the complexity of synchronization protocols and coordination increases
Solution Approach 1:
The system implements periodic frame timing synchronization where zone tags exchange timing information at regular intervals. This periodic action maintains microsecond-level synchronization without requiring continuous complex coordination, as the timing relationships are re-established periodically rather than continuously managed.
Solution Approach 2:
Zone tags exchange timing information and measured distances through the position location server, which uses this feedback to compute positions and can adjust timing references to maintain synchronization. The feedback loop ensures that timing drift is corrected while keeping the synchronization protocol relatively simple through iterative refinement.
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
This approach enables accurate proximity detection and position location with room-level precision, improving the ability to associate individuals or assets within close proximity, enhancing tracking and navigation in various environments.
Implementation Method 1
making round trip delay measurements between the mobile tags and the zone tags
Data Source
AI summary
A system for computing accurate position location coordinates of tags used for tracking assets and people include a first network of access points to help compute a first approximation of the tag position location, a second network of access points underlying the first network for fine position location determination, and a position location server for controlling the second network of access points and computing position location based on round trip delay measurements between tags and the access points.