Dynamic Beamforming for Continuous Wireless Power Transfer
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Solution Overview
Problem
Current Wireless Power Transfer (WPT) systems using radiative coupling and beamforming face challenges such as device identification issues, interference among multiple energy harvesters, and the need for orthogonal channels, which occupy spectrum, and codebook-based beamforming approaches that are less flexible and power-consuming.
Innovation Solution
The system employs a dual-frequency cross-hopping scheme where the energy transmitter uses two different frequencies for WPT and channel estimation, allowing continuous channel tracking and efficient beamforming, using a spread spectrum signature as a device identifier and utilizing Time Division Duplexing (TDD) and Frequency Division Duplexing (FDD) to partition WPT and feedback transmission, enabling passive energy harvesters to modulate and feedback signatures across frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If beamforming is used to focus energy transmission, then energy transmission range and focus are improved, but Channel State Information (CSI) feedback is required which consumes power at the energy harvester
Solution Approach 1:
The patent introduces a signature-based feedback mechanism as an intermediary between the energy transmitter and energy harvester. Instead of requiring full CSI feedback, the system uses simple signature signals that the energy harvester transmits back to the transmitter. These signatures allow the transmitter to estimate channel conditions and adjust beamforming without the energy harvester needing to consume significant power on complex channel measurement and feedback transmission.
Solution Approach 2:
The patent changes the feedback parameter from full CSI (which requires significant processing and transmission power) to simple signature signals. By modifying what information is fed back in the system, the energy consumption at the harvester is reduced while still enabling the transmitter to perform effective beamforming through signature-based channel estimation.
2Reliability
If orthogonal channels are used for multiple energy harvesters, then interference is reduced, but spectrum resources are occupied
Solution Approach 1:
The patent applies local quality by assigning unique signatures to different energy harvesters rather than allocating orthogonal channels to each. Each harvester operates in the same spectrum but with its own distinctive signature, allowing the transmitter to differentiate and serve multiple harvesters simultaneously without requiring orthogonal channel separation. This reduces spectrum occupation while maintaining interference reduction through signature-based identification.
3Device complexity
If codebook-based beamforming is used, then device identification is simplified, but flexibility and power efficiency are reduced
Solution Approach 1:
The patent implements preliminary action by having energy harvesters pre-register their signatures with the energy transmitter before actual power transfer begins. This pre-registration phase allows the transmitter to build a database of device identifiers and associate them with their locations and characteristics. During operation, the transmitter can quickly identify devices using these pre-stored signatures without requiring complex real-time analysis, maintaining simplicity while enabling flexible, adaptive beamforming to multiple devices.
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 ensures continuous and efficient WPT, improves energy reception at the energy harvester, reduces power consumption, and increases reliability by allowing channel tracking and beamforming concentration on the target device, even for passive devices without initial power or CSI feedback.
Implementation Method 1
transmitting, during the time slot (TSi,j) of the time period (TPi) on a frequency fmod(i,2), a radio frequency signal (ST(i,j)) that is modulated with a signature of a particular energy harvester
Implementation Method 2
attempting, during the time period (TPi), to receive, from the particular energy harvester on a frequency fmod(i+1,2), a radio frequency signal (SR(i)) that is modulated with the signature of the particular energy harvester
Data Source
AI summary
Systems and methods are disclosed herein for Wireless Power Transfer (WPT) using radiative coupling and dynamic beamforming. In some embodiments, a method of operation of an Energy Transmitter (ET) comprises, for each time period (TPi) of a plurality of time periods ({TPi}i=0,1, . . . , I-1), for each time slot (TSi,j) of one or more time slots ({TSi,j}j=0,1, . . . , J-1), transmitting, during TSi,j of TPi on a frequency fmod(i,2), a radio frequency signal (ST(i,j)) that is modulated with a signature of a particular Energy Harvester (EH). The method further comprises, for each TPi, attempting, during TPi, to receive, from the particular EH on a frequency fmod(i+1,2), a radio frequency signal (SR(i)) that is modulated with the signature of the particular EH. In this manner, continuous WPT is provided. Corresponding embodiments of an ET are also disclosed. Embodiments of a method performed by an EH and corresponding embodiments of an EH are also disclosed.