IoT Backscatter Uplink With Frequency-Splitting SWIPT
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Solution Overview
Problem
Existing IoT devices face challenges with power efficiency and interference in communication due to high peak-to-average power ratio and nonlinear distortion in PS-SWIPT, and backscattering techniques suffer from complex interference cancellation and low data transfer rates.
Innovation Solution
A frequency-splitting (FS)-simultaneous wireless information and power transfer (SWIPT) system that allows IoT devices to collect energy and decode data using a first frequency, determine a second frequency band for uplink transmission, and transmit information using backscattering, with frequency allocation based on energy, channel environment, and traffic considerations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If power-splitting (PS) SWIPT technique is used to simultaneously transmit power and information, then power-free operation of low-power IoT sensor is enabled, but power collecting efficiency and communication performance are deteriorated due to high peak-to-average power ratio and nonlinear distortion
Solution Approach 1:
The patent divides the frequency band into multiple subcarriers, with specific subcarriers designated for power transfer and others for information transmission. This frequency-domain segmentation allows separate optimization of power collecting and communication, resolving the contradiction between enabling power-free operation and maintaining power collecting efficiency.
2Power
If communication signal power is increased for energy transmission, then energy transmission capability is improved, but strong interference occurs to other users or systems sharing the frequency
Solution Approach 1:
The frequency spectrum is segmented into dedicated power transfer subcarriers and information subcarriers. By concentrating power transmission energy on specific subcarriers rather than spreading it across the entire band, the system achieves high energy transmission capability while limiting interference to other frequency-sharing systems.
Solution Approach 2:
The patent introduces frequency-selective processing as an intermediary mechanism that mediates between power transmission requirements and interference constraints. The gateway performs channel estimation and identifies suitable subcarriers for power transfer, acting as an intermediary that optimizes the trade-off between energy transmission and interference management.
3Use of energy by moving object
If ambient backscatter communication uses modulated RF signal as carrier, then energy-efficient communication is achieved, but complex interference cancellation is required to remove direct link interference and decode mixed information
Solution Approach 1:
The patent segments the frequency spectrum so that power transfer subcarriers carry only power signals without information modulation, while information is transmitted on separate subcarriers. This segmentation eliminates direct link interference on power subcarriers, allowing simple envelope detection at the backscatter device without complex interference cancellation, thus maintaining energy efficiency while reducing receiver complexity.
4Object-affected harmful factors
If envelope detection is used to remove RF signal source, then direct link interference is reduced, but data transfer rate is limited to very low rates
Solution Approach 1:
The patent divides frequency resources into power subcarriers and information subcarriers. Power subcarriers use simple envelope detection to eliminate DLI, while information subcarriers support higher data rates through conventional coherent detection. This segmentation allows the system to achieve both low interference and high data transfer rates by using appropriate detection methods for each frequency segment.
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
Enhances energy and frequency efficiency in uplink/downlink communications for IoT devices by minimizing interference and optimizing frequency usage, enabling high data transfer rates and reduced power consumption.
Implementation Method 1
collecting energy by simultaneously receiving power having a first frequency
Implementation Method 2
transmitting tag information in the second frequency band using the power having the first frequency in a backscattering manner
Data Source
AI summary
A backscattering method for an Internet-of-things (IoT) device includes a frequency-splitting (FS)-simultaneous wireless information and power transfer (SWIPT) wireless communication system. The backscattering method includes collecting energy by simultaneously receiving power having a first frequency, receiving data having a first frequency band, and decoding the data; determining a second frequency band to uplink; and transmitting tag information in the second frequency band using the power having the first frequency in a backscattering manner.