Multi-Antenna Signaling for Passive RFID Tags
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Solution Overview
Problem
Passive RFID tags face limitations in transmission distance and data rate due to low power and inefficient energy harvesting, which restricts their operational range and effectiveness in communication with interrogators.
Innovation Solution
A multi-antenna signaling scheme incorporating a Retrodirective Array Phase Modulator (RAPM) and Staggered Pattern Charge Collector (SPCC) enhances energy harvesting and data transmission by using multiple antennas for efficient energy collection and phase modulation, allowing passive RFID tags to transmit higher-powered signals with increased data rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If passive RFID tags use backscatter signal modulation to reflect data signals, then power consumption is reduced, but transmission distance and data rate are limited
Solution Approach 1:
The patent combines multiple antennas at the RFID tag with multiple antennas at the reader to create a multi-antenna backscatter communication system. This merging of multiple antenna elements enables spatial diversity and beamforming capabilities that simultaneously extend transmission distance and increase data rate while maintaining the low power consumption characteristics of passive backscatter tags.
Solution Approach 2:
The patent introduces spatial dimensionality by deploying multiple antennas in a geometric array configuration. This dimensional expansion from single-antenna to multi-antenna systems enables the use of spatial processing techniques such as beamforming and spatial multiplexing, which overcome the limitations of traditional single-antenna backscatter communication in terms of range and data rate.
2Use of energy by moving object
If passive RFID tags use backscatter signal modulation, then power consumption is reduced, but transmission distance is limited
Solution Approach 1:
The patent combines multiple antennas at the RFID tag with multiple antennas at the reader to create a multi-antenna backscatter communication system. This merging of multiple antenna elements enables spatial diversity and beamforming capabilities that simultaneously extend transmission distance and increase data rate while maintaining the low power consumption characteristics of passive backscatter tags.
Solution Approach 2:
The patent implements feedback mechanisms where the reader transmits pilot signals and the tag responds with backscatter signals containing channel state information. This feedback enables the reader to adaptively adjust beamforming weights and modulation schemes to maximize communication distance while maintaining reliability, all without requiring additional power at the passive tag.
3Speed
If multiple antennas are used for energy harvesting and data transmission, then transmission range and data rate increase, but device complexity increases
Solution Approach 1:
The patent segments the multi-antenna system into distinct functional components: energy harvesting circuits connected to antenna elements, backscatter modulation circuits, and control logic. This segmentation allows each component to be optimized independently and simplifies the overall system architecture by clearly defining the role of each subsystem, thereby managing complexity while maintaining performance benefits.
Solution Approach 2:
The patent designs the antenna elements to serve multiple functions simultaneously: they act as both receiving antennas for energy harvesting and transmitting antennas for backscatter communication. This multi-functionality reduces the need for separate hardware components, thereby managing complexity while maintaining performance benefits.
4Length of stationary object
If multiple antennas are used for energy harvesting, then transmission range increases, but device complexity increases
Solution Approach 1:
The patent segments the multi-antenna system into distinct functional components: energy harvesting circuits connected to antenna elements, backscatter modulation circuits, and control logic. This segmentation allows each component to be optimized independently and simplifies the overall system architecture by clearly defining the role of each subsystem, thereby managing complexity while maintaining performance benefits.
Solution Approach 2:
The patent combines multiple antennas at the RFID tag with multiple antennas at the reader to create a multi-antenna backscatter communication system. This merging of multiple antenna elements enables spatial diversity and beamforming capabilities that simultaneously extend transmission distance and increase data rate while maintaining the low power consumption characteristics of passive backscatter tags.
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 solution significantly increases the transmission range and data rate between RFID tags and reader units, improving the operational efficiency and effectiveness of passive RFID systems without violating spectrum regulations or increasing transmit power.
Implementation Method 1
A retrodirective array phase modulator is disclosed that is configured for quadrature phase shift keying
Implementation Method 2
The RFID tag may also use a charge collector for harvesting energy from an incident electromagnetic wave
Implementation Method 3
The retrodirective array phase modulator has a retrodirective antenna array with at least one antenna pair
Data Source
AI summary
A multi-antenna signaling scheme, system and method for passive or low-powered RF devices, such as a radio frequency identification tag, are herein described. In one embodiment, the presently disclosed subject matter discloses a Retrodirective Array Phase Modulator which is configured to allow RFID tags to return higher-powered signals with higher data rates back to an RFID interrogator or reader unit. In some configurations, pattern strobing is used which is an array-based transmission technique for stepping or sweeping an RF waveform through space so that passive radio devices may more efficiently harvest energy without increasing transmit power. In some configurations, the presently disclosed subject matter may also use a Staggered Pattern Charge Collector to boost the collection of microwave power.