Passive RFID Reference Signals Using RF Energy Harvesting
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Solution Overview
Problem
Existing wireless communications systems face challenges in configuring passive wireless devices, such as RFID tags, to perform reference signal measurements and transmissions due to their lack of internal power sources, limiting their ability to perform beamforming or decoding of signals.
Innovation Solution
A wireless device sends parameters to passive RFID devices to enable them to perform channel state information (CSI) measurements and backscatter sounding reference signals (SRS), using harvested energy from received signals to activate and communicate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If passive wireless devices are used without internal power sources, then device complexity and power consumption are reduced, but the ability to perform reference signal measurements and transmissions is limited
Solution Approach 1:
The patent introduces an active wireless device as an intermediary that performs reference signal measurements and transmissions on behalf of passive wireless devices. The active device receives configuration parameters for the passive device, performs CSI measurements and SRS transmissions using its own power source, and reports results to the network, thereby enabling measurement capabilities without requiring power sources in the passive devices.
Solution Approach 2:
The passive wireless device harvests energy from received RF signals to autonomously perform backscatter transmissions of reference signals. The device uses the harvested energy to modulate and transmit SRS signals without an internal power source, enabling self-service operation for reference signal transmission while maintaining passive device simplicity.
2Use of energy by moving object
If passive wireless devices harvest energy from received signals, then internal power sources are eliminated, but the duration and consistency of signal transmissions are limited
Solution Approach 1:
The active wireless device performs reference signal measurements and transmissions in advance before the passive device needs to communicate. By pre-performing CSI measurements and SRS transmissions using its own power source, the active device ensures that measurement data is available even when the passive device's harvested energy may be insufficient for sustained transmissions.
Solution Approach 2:
The patent combines the measurement and transmission functions of the passive device with the active device's capabilities. The active device performs measurements and transmissions, merging its powered operations with the passive device's energy-harvesting backscatter capabilities to extend effective transmission duration beyond what the passive device could achieve alone.
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 passive RFID devices to send CSI reports and backscatter SRS, overcoming the limitations of internal power sources and enhancing communication capabilities.
Implementation Method 1
using harvested energy from received signals to activate and communicate
Implementation Method 2
backscattering a sounding reference signal (SRS)
Data Source
AI summary
Methods, systems, and devices for wireless communications are described. A wireless device, such as a radio frequency identifier (RFID) device, may receive a trigger message from another wireless device via a continuous radio frequency (RF) waveform that activates the RFID device. The trigger message may include one or more parameters for a channel state information (CSI) report, one or more sounding reference signals (SRSs), or both. The RFID device may send the CSI report, the SRSs, or both in a message via a portion of a modulated continuous RF waveform. The contents of the message may be based on the parameters and a capability of the RFID device.