Backscatter Communication Element With Independent Power And Spread Spectrum Modulation
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Solution Overview
Problem
Conventional UHF RFID tag systems have limited operational range and cannot dynamically update information, making them unsuitable for seamless tracking of consumables in a home environment without user intervention.
Innovation Solution
A backscatter-based communication system with independent power sourcing for the communication element, dual antennas for crosstalk minimization, carrier self-cancellation techniques, binary phase shift keying, direct sequence spread spectrum modulation, and low phase noise signal sources to increase range and sensitivity, along with onboard processing and sensors for dynamic data updates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional UHF RFID tags use backscatter modulation with limited transmitted power, then the tag hardware remains simple and low cost, but the operational range is limited
Solution Approach 1:
The patent changes the power parameter by introducing an independent power source (battery or energy harvesting device) in the tag, allowing the tag to operate without relying solely on the reader's transmitted power. This enables extended operational range while keeping the tag hardware relatively simple, as the additional power source is a basic component that does not significantly increase complexity.
2Length of stationary object
If the reader transmits at maximum power to increase range, then the communication range increases, but the backscattered signal becomes buried in the transmitted signal noise
Solution Approach 1:
The patent introduces spread spectrum modulation as an intermediary technique that spreads the signal energy over a wider frequency spectrum. This allows the reader to distinguish the weak backscattered signal from the strong transmitted signal by using correlation detection with the spreading code, effectively separating the signals in the frequency domain and enabling sensitive detection even at extended ranges.
Solution Approach 2:
The patent replaces traditional signal separation methods with spread spectrum modulation and correlation detection. Instead of relying on simple amplitude or frequency separation, the system uses temporal spreading and correlation processing to distinguish between the transmitted and backscattered signals, significantly improving signal detection sensitivity in the presence of strong interfering signals.
3Device complexity
If conventional RFID tags use static information storage, then the tag structure remains simple, but the information cannot be dynamically updated
Solution Approach 1:
The patent introduces dynamic information update capability by enabling the tag to receive commands from the reader and update its stored information accordingly. The tag can now dynamically change its state based on external inputs, such as updating product status information when a consumable is used. This maintains relative structural simplicity while adding adaptability through bidirectional communication and programmable memory.
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 extended operational range up to 50-100 meters and allows for dynamic information updates, providing a seamless user experience for tracking consumables in a home environment while maintaining cost-effectiveness.
Implementation Method 1
powering of the communication element (tag or label) from the RF transmitted by the hub/reader means that a minimum amount of energy needs to be present at the communication element in order for it to operate
Implementation Method 2
the tag transmitting it's data by backscatter modulation of this incident signal
Data Source
AI summary
There is described a communication system (1) comprising a central unit (3) and a communication element (20). The central unit (3) comprises at least one RF antenna (4), a transmitter (6) configured to transmit a RF signal and a receiver (8) configured to receive a backscattered RF signal. The communication element (20) comprises a RF antenna (22) and a modulator (23) configured to backscatter the RF signal. The communication element (20) comprises a means for modulating the backscattered RF signal into a spread spectrum backscattered RF signal, and a means for supplying power.