Backscatter Channel Estimation for Wireless Power Optimization

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Solution Overview

Problem

Current wireless power transfer systems require complex and power-consuming coherent channel measurements for optimizing power transfer to wirelessly powered devices, which is challenging for milliwatt- or microwatt-class devices due to the need for detailed channel information and active participation from the devices.

Innovation Solution

A system that uses backscatter signals from wirelessly powered devices to estimate channel information, allowing for optimization of wireless power transfer by adjusting the wireless power signal based on this information, thereby shifting the power cost and complexity from the devices to the transmitter side.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If coherent channel measurements are performed to optimize wireless power transfer, then power transfer efficiency is improved, but power consumption and device complexity increase significantly

Engineering Contradiction:

Improvepower transfer efficiencyVSAvoidpower consumption at devices

Core Design Contradiction:

Loss of energyVSUse of energy by moving object

Solution Approach 1:

Instead of having the wirelessly powered device perform active channel measurements and send feedback (forward-link approach), the system uses backscatter signals from the device to enable the transmitter to estimate channel information (reverse-link approach). This inverts the traditional measurement direction, allowing channel estimation without active device participation.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The backscatter signal acts as an intermediary that carries channel information from the device to the transmitter without requiring the device to actively measure or process channel data. The transmitter extracts channel information from these passive backscatter signals, eliminating the need for dedicated measurement hardware and power consumption at the device.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Productivity

If wirelessly powered devices actively participate in channel measurements and power optimization, then power transfer optimization is improved, but device complexity and power cost increase

Engineering Contradiction:

Improvepower transfer optimizationVSAvoidmeasurement and control complexity

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The system extracts channel information from the backscatter signals that are already being transmitted by the device for communication purposes. This extraction happens at the transmitter side without requiring any additional measurement hardware, processing circuits, or power consumption at the wirelessly powered device.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The backscatter signal serves multiple functions simultaneously: it enables communication from the device to the transmitter and provides the medium for channel estimation. This multi-functionality eliminates the need for separate measurement signals and processing, reducing device complexity while maintaining optimization capability.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Measurement precision

If detailed channel information is obtained through active measurements, then power transfer precision is improved, but the power cost and synchronization requirements increase

Engineering Contradiction:

Improvechannel information accuracyVSAvoidpower cost for measurements

Core Design Contradiction:

Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The wirelessly powered device uses its own backscatter communication signals to provide the channel information needed for power optimization. The device essentially serves itself by generating signals that contain the necessary channel data, which are then extracted by the transmitter without requiring any additional power or resources from the device.

Inventive Principle:

Principle #25Self-service

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

This approach enables efficient optimization of wireless power transfer with minimal power costs at the devices, allowing for integration into low-power devices and promoting constructive interference, equivalent to forward-link-based optimization with cooperative devices.

Implementation Method 1

A system that uses backscatter signals from wirelessly powered devices to estimate channel information

Methodology Applied

Scientific EffectBackscatter: Scattering

Data Source

PatentUS11133717B2Wireless power systems including determination of channel transfer function from backscatter signals

Publication Date: 2021.09.28 UNIV OF WASHINGTON

AI summary

Examples described herein utilize a backscatter signal provided by a wirelessly powered device to estimate channel information, (e.g., a channel transfer function) between the wirelessly powered device and a transmitter system. The channel information may be used to optimize MIMO power transfer for linear as well as nonlinear backscatter devices. Examples of die method ‘may shift some or all of the power cost and complexity of coherent channel measurements from the WFD to the transmitters), and allow WPT optimization to milliwatt- or microwatt-class wirelessly powered devices.