Backscatter Frequency Shifting for In-Band Self-Interference Mitigation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Wireless communications systems face interference and power constraint challenges due to self-interference and transmission power limitations in backscatter communications, particularly in ambient wireless devices with minimal power and processing capabilities.
Innovation Solution
Implementing dual-band and in-band frequency shift techniques, where ambient wireless devices shift the frequency of backscattered signals relative to the received continuous wave to mitigate interference and power constraints, using local oscillators and reader devices to assist in larger frequency shifts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If backscatter communications are implemented in ambient wireless devices, then communication functionality is enabled, but self-interference and power constraints worsen
Solution Approach 1:
The frequency band is segmented into multiple sub-bands, and different carrier frequencies are assigned to different devices or time slots. This frequency division approach separates the transmitted and received signals in the frequency domain, reducing self-interference while maintaining communication functionality in power-constrained ambient devices
Solution Approach 2:
A reader device acts as an intermediary that transmits carrier waves to backscatter devices and receives their responses. The reader device handles the complex frequency management and signal processing, allowing ambient devices to perform simple backscatter operations without generating excessive self-interference
2Object-generated harmful factors
If frequency shift techniques are implemented, then self-interference is reduced, but device complexity increases
Solution Approach 1:
The system dynamically adjusts carrier frequencies and frequency shifts based on channel conditions and device capabilities. The reader device coordinates frequency assignments and shifts, allowing ambient devices to reduce their own complexity while the system as a whole adapts to minimize self-interference
Solution Approach 2:
The reader device serves as an intermediary that manages frequency shift coordination. It transmits multiple carrier waves at different frequencies and receives backscattered signals, performing the complex frequency management centrally while keeping individual ambient device complexity low
3Reliability
If multiple carrier waves are transmitted at different frequencies, then frequency diversity and interference mitigation are improved, but power consumption increases
Solution Approach 1:
A single reader device performs multiple functions: transmitting multiple carrier waves at different frequencies, receiving backscattered signals, and coordinating frequency management for multiple ambient devices. This consolidates power consumption in one device while enabling frequency diversity across the system
Solution Approach 2:
The system uses multiple carrier waves and frequency shifts beyond what a single device would need, but distributes this complexity across the reader device and multiple ambient devices. The ambient devices perform only simple backscatter operations on received carriers, keeping their power consumption minimal while achieving system-level interference mitigation
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
Reduces self-interference and power constraints by allowing backscattered signals to operate within the same frequency band as the continuous wave, enhancing communication efficiency and reducing device and energy costs.
Implementation Method 1
The wireless device may perform a nonlinear operation to obtain a frequency shift carrier wave based on a difference between a frequency of the first carrier wave and a frequency of the second carrier wave
Implementation Method 2
sending a signal backscattered on a continuous wave received at the wireless device, where the backscattered signal is sent at a frequency that is shifted, relative to a frequency at which the continuous wave is received
Data Source
AI summary
Methods, systems, and devices for wireless communications are described. An ambient wireless device may receive, within a frequency band, first and second carrier waves separated by a frequency shift value. The frequency shift value may represent a frequency shift that enables the ambient wireless device to shift a backscattered signal from a downlink portion of a frequency band to an uplink portion of the frequency band. The ambient wireless device may perform a nonlinear operation to obtain a frequency shift carrier wave that is based on the frequency difference between the first carrier wave and the second carrier wave. The ambient wireless device may send a signal backscattered on a continuous wave received at the ambient wireless device, where the backscattered signal is sent at a frequency that is shifted, relative to a frequency at which the continuous wave is received, based on the frequency shift value.