Passive RF Backscatter Tags for Indoor Localization
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Solution Overview
Problem
Current radio frequency (RF) based localization solutions for indoor tracking are either expensive and inaccurate for scalable deployment or cost-effective but lack precision, failing to provide real-time visibility and efficient tracking of assets in warehouses and fulfillment centers.
Innovation Solution
A novel RF-based localization system, uShift, employs dual-band (UHF+UWB) RF transceivers as beacons and passive, battery-less UWB tags, leveraging the RF backscattered channel as a virtual distributed antenna to compute the location of tags without synchronization between beacons, enabling accurate and real-time tracking at a low cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If passive RF tags are used for localization, then deployment cost is reduced, but localization accuracy deteriorates
Solution Approach 1:
The patent combines passive RF tags with ultra-wideband (UWB) technology to create a hybrid system that leverages the cost-effectiveness of passive tags while achieving the high localization accuracy of UWB. The passive tag structure is merged with UWB transceiver capabilities, allowing the system to maintain low deployment costs while significantly improving measurement precision to sub-meter accuracy levels.
Solution Approach 2:
The localization system uses a composite approach by integrating multiple RF technologies (passive RFID and UWB) into a single tag unit. This composite structure allows the system to benefit from both technologies: the passive RFID component provides low cost and simple deployment, while the UWB component delivers high precision time-of-flight measurements for accurate localization.
2Measurement precision
If active RF localization solutions are used, then localization accuracy is improved, but deployment cost increases
Solution Approach 1:
The system applies partial action by using passive tags that only transmit when illuminated by reader signals, rather than continuously active transmitters. This reduces the power requirements and cost of the tag while still achieving accurate localization through time-of-flight measurements during active illumination periods, avoiding the need for fully active expensive UWB transmitters at every location.
Solution Approach 2:
The patent introduces an intermediary approach where passive tags serve as mediators between the low-cost RFID infrastructure and high-precision UWB localization requirements. The passive tag structure acts as an intermediary that converts incoming RF signals into measurable time-of-flight data, enabling accurate localization without requiring expensive active transmitters at each tag location.
3Measurement precision
If synchronized RF beacons are deployed for TDoA measurement, then localization accuracy is improved, but system complexity increases
Solution Approach 1:
The patent extracts the synchronization requirement from the tag side and places it entirely on the reader/beacon side. By using passive tags that do not require synchronization capabilities, the system eliminates the complexity of synchronized operation at the tag level while maintaining TDoA measurement accuracy through centralized control and coordination of the active readers/beacons.
Solution Approach 2:
The system inverts the traditional active-passive relationship by making the readers/beacons the active synchronized elements and the tags completely passive. This inversion shifts all synchronization complexity to the reader infrastructure, which is easier to control and manage centrally, while tags remain simple, low-cost passive devices without synchronization requirements.
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
uShift offers high localization accuracy and real-time tracking of assets at a low deployment and maintenance cost, suitable for various industry verticals, including warehouses, event centers, and industrial automation, by using passive, low-cost UWB tags and dual-band RF transceivers.
Implementation Method 1
a passive RF backscatter tag associated with a product and configured to generate an Ultra-Wideband (UWB) signal from the excitation signal
Data Source
AI summary
A product locating system is provided. The system includes at least one Radio Frequency (RF) backscatter transmitter configured to emit a main carrier RF signal that forms an excitation signal. The system further includes a passive RF backscatter tag associated with a product and configured to generate an Ultra-Wideband (UWB) signal from the excitation signal. The system also includes at least one RF backscatter receiver configured to simultaneously receive both the excitation signal from the at least one RF backscatter transmitter and the UWB signal from the passive RF backscatter tag, and compute the time-difference-of-arrival (TDoA) therebetween. TDoA information from multiple RF backscatter receivers, including the at least one RF backscatter receiver, is aggregated to compute the location of the product to which the passive RF backscatter tag is attached.