Radar Backscatter Ranging for Wireless Devices
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Solution Overview
Problem
Existing RFID systems have limited capability in determining the range or location of a tag or object, necessitating an improved method and system for identification and ranging.
Innovation Solution
A radar-based identification and range finding system using offset backscattering, where a radar antenna transmits an electromagnetic wave and the wireless device backscatters a frequency offset signal, allowing for power measurement to determine the range or location by employing techniques such as power measurement and continuous wave signals with frequency modulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional RFID backscattering method is used, then power consumption is reduced and simplicity is maintained, but ranging capability is limited
Solution Approach 1:
The patent combines RFID backscattering technology with radar ranging technology into a unified system. The RFID tag's backscattering mechanism is enhanced to carry ranging information by modulating the backscattered signal with distance-dependent phase or frequency shifts, allowing simultaneous identification and ranging functions without requiring completely separate systems
Solution Approach 2:
The patent utilizes changes in signal parameters (frequency, phase, or time delay) of the backscattered electromagnetic waves to encode ranging information. By measuring the phase difference or frequency shift between transmitted and backscattered signals, the system calculates distance based on the known speed of light and signal propagation time
2Measurement precision
If radar techniques are applied for accurate ranging, then measurement precision is improved, but energy consumption increases
Solution Approach 1:
The RFID tag passively harvests energy from the reader's transmitted electromagnetic signal through rectification circuits, storing it in capacitors to power its backscattering modulation and ranging signal generation. This eliminates the need for an independent power source in the tag, allowing radar-like ranging functionality without additional battery power consumption
Solution Approach 2:
The reader device performs multiple functions simultaneously: it provides power to passive tags through electromagnetic coupling, communicates data bidirectionally via backscattering, and conducts ranging measurements by analyzing the backscattered signal characteristics. This multi-functionality reduces overall system energy consumption compared to deploying separate RFID and radar systems
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 determination of the range or location of a wireless device using radar techniques, improving upon the limitations of existing RFID systems by utilizing frequency offset signals for precise distance calculation.
Implementation Method 1
a radar antenna transmits an electromagnetic wave
Implementation Method 2
the wireless device backscatters a frequency offset signal
Implementation Method 3
continuous wave signals with frequency modulation
Implementation Method 4
A rectify circuit 131 in the tag 130 collects and stores the energy 140 for powering the other circuits
Data Source
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AI summary
A method for identifying and ranging a wireless device, comprising: transmitting an original radar signal from a detecting system; in response to the original radar signal, receiving a modulated radar signal at the detecting system, the modulated radar signal being backscattered from an antenna of the wireless device and containing information pertaining to the wireless device, and the modulated radar signal being a frequency offset version of the original radar signal; and, using a processor at the detecting system, determining an identity and a range of the wireless device from the modulated radar signal.