Backscatter Termination Circuit for Low-Power IoT
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Solution Overview
Problem
Conventional Wi-Fi transceivers require high power levels, making them unsuitable for low-power IoT devices, and existing backscatter communication solutions either rely on custom hardware or have limited range and data rates.
Innovation Solution
A termination circuit for backscatter communication in an integrated wake-up receiver tag device, utilizing a reflection termination circuit and a MIMO termination circuit with offset reflection coefficients and unique phase shifts, enabling efficient data encoding and decoding using commodity Wi-Fi hardware.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional Wi-Fi transceivers are used, then communication performance is maintained, but power consumption increases significantly
Solution Approach 1:
The patent extracts the RF reception function from the conventional Wi-Fi transceiver and implements it separately in the backscatter tag. The tag uses a simple RF front-end with envelope detector and discriminator circuitry, while the Wi-Fi transceiver remains in the reader. This separation allows the tag to operate at very low power (micro-watt level) while maintaining Wi-Fi communication performance through the reader's full-featured transceiver.
Solution Approach 2:
The patent introduces backscatter modulation as an intermediary mechanism between the Wi-Fi reader and the IoT tag. Instead of the tag actively transmitting Wi-Fi signals (which would consume high power), the tag passively modulates the incident RF signal through impedance changes, creating a backscattered signal that carries data. This intermediary backscatter mechanism enables low-power operation while maintaining communication functionality.
2Use of energy by moving object
If custom tone generators are used for backscatter communication, then low power operation is achieved, but deployment complexity increases
Solution Approach 1:
The patent makes the Wi-Fi reader serve multiple functions: it acts as both the Wi-Fi communication device and the RF signal source for backscatter communication. The reader's existing Wi-Fi transceiver generates the incident RF signals that the tag backscatters, eliminating the need for separate custom tone generators. This universal approach leverages existing Wi-Fi infrastructure for dual purposes, simplifying deployment while maintaining low power operation.
Solution Approach 2:
The patent changes the operational parameters of the Wi-Fi system by using the reader's RF output as the incident signal for backscatter communication. Instead of requiring the tag to generate tones at specific frequencies, the system adapts to the reader's RF characteristics. The tag's impedance modulation responds to the incident RF signal's envelope and phase, enabling communication without custom tone generation hardware.
3Adaptability or versatility
If Wi-Fi signals are used for backscatter communication, then existing infrastructure is leveraged, but communication range is limited
Solution Approach 1:
The patent implements dynamic impedance modulation in the backscatter tag, where the tag's impedance changes in response to the incident RF signal's envelope and phase. This dynamic modulation allows the tag to encode information by varying its reflection characteristics, enabling more efficient use of the available RF energy and extending communication range. The dynamic response to RF signal variations allows for more robust data transmission over longer distances compared to static modulation schemes.
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 achieves improved range and data rates for Wi-Fi backscatter communication, with a range of approximately 24 meters in a retroreflective configuration, while maintaining low power consumption and compatibility with existing Wi-Fi standards.
Implementation Method 1
a first branch having an open load and a shorted load with first branch offset reflection coefficients and with a connection to an antenna
Data Source
AI summary
Termination circuits for backscatter communication in an integrated wake-up receiver tag device. A reflective termination circuit includes a first branch having an open load and a shorted load with first branch offset reflection coefficients and with a connection to an antenna. A second branch has a capacitive load and an inductive load with second branch offset reflection coefficients and with a connection to an antenna. A MIMO termination circuit includes plurality of transmission lines each providing a unique delay that is offset compared to other ones of the plurality of transmission lines. Switched connections to a corresponding array of antennas introduce a delay between a received and backscattered signal at each antenna in the array of antennas.