Indoor Location Tracking Using Zone Tags and Periodic Ranging
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Solution Overview
Problem
Existing location and tracking systems in indoor environments often lack the precision required for applications needing accuracy within one meter, such as associating individuals or assets in close proximity, especially in settings like hospitals, manufacturing, and retail, where room-level accuracy is necessary.
Innovation Solution
A position location determination system utilizing mobile tags and zone tags within a wireless network, where zone tags provide range measurements using Round Trip Delay or Time Of Arrival techniques, allowing for triangulation to estimate the position of mobile tags with high precision, and incorporating power-saving sleep modes to conserve energy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If Wi-Fi or Bluetooth networks are used for location tracking, then the system can cover large indoor areas, but the position accuracy is limited to within a few meters
Solution Approach 1:
The patent introduces zone tags as intermediary devices deployed throughout the indoor environment. These zone tags act as mediators between the mobile tag and the central server, performing local range measurements and triangulation calculations. This intermediary layer enables high-precision positioning (within one meter) by creating a distributed measurement network that supplements the existing Wi-Fi infrastructure without requiring complete system replacement
Solution Approach 2:
The system divides the indoor space into multiple zones, each monitored by a zone tag. Rather than using a single centralized system for entire building-wide tracking, the space is segmented into smaller operational units. Each zone tag independently performs measurements and calculations for its local area, then reports to the central server. This segmentation enables high precision positioning while distributing system complexity across multiple simple nodes rather than one complex centralized system
2Measurement precision
If continuous range measurements are performed to maintain high position accuracy, then location precision is improved, but energy consumption increases
Solution Approach 1:
The patent implements periodic ranging intervals where mobile tags and zone tags perform range measurements only at scheduled time intervals rather than continuously. The system dynamically adjusts the measurement frequency based on whether the mobile tag is stationary or moving. When stationary, measurements occur less frequently; when moving, the interval decreases to maintain positioning accuracy. This periodic measurement approach significantly reduces power consumption while preserving positioning accuracy when needed
Solution Approach 2:
The system dynamically adapts the measurement interval based on the mobility state of the tagged object. The position location server monitors movement detection and adjusts the ranging frequency accordingly. This dynamic adjustment ensures that energy is consumed only at the necessary rate to maintain positioning accuracy, rather than using fixed continuous measurements. The system transitions between different measurement modes based on real-time conditions, optimizing the balance between precision and power consumption
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
The system achieves high precision in determining the relative location of assets within a transmission zone, enabling accurate proximity detection and position updates, thereby addressing the need for room-level accuracy in various applications.
Implementation Method 1
zone tags providing range measurements with mobile tags using Round Trip Delay or Time Of Arrival techniques, allowing for triangulation to estimate the position of mobile tags
Data Source
AI summary
A position location system is described for determining position of mobile Tags attached to assets or people. Zone Tags are installed in the venue to assist in position location estimation of mobile Tags. Time is divided into intervals, each interval comprising at least one range measurement sub-interval, and an idle sub-interval where zone Tags and mobile Tags go to sleep to save power. A zone Tag or mobile Tag is designated as the anchor network element. The anchor network element contends and seizes the communications channel at the beginning of each interval to start the range measurement phase. Mobile Tag position location estimates are made periodically. Between the periodic range measurement based position estimates, mobile Tag sensor readings are used to update the mobile Tag's position location. The period between range measurement based position updates is adjusted based on the statistics of the differences between the range measurements based position estimate and the sensor based position updated.