Shifted Backscatter Channel Estimation for Passive IoT Power Transfer
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Solution Overview
Problem
Current wireless communication systems, particularly 5G, face inefficiencies in supporting passive IoT devices due to high input power requirements and limited range, making it challenging to efficiently power and communicate with RFID-type sensors in industrial applications like asset management and logistics.
Innovation Solution
The implementation of shifted backscattering-based channel estimation for wireless power transfer, which involves a network device transmitting a continuous wave signal, receiving backscatter signals from passive devices at specific frequency shifts, and determining optimal channels for energy signal transmission to enhance energy harvesting efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If conventional wireless communication methods are used to support passive IoT devices, then communication can be established, but high input power requirements and limited range are incurred
Solution Approach 1:
The patent applies parameter changes by utilizing frequency-shifted backscattering, where passive devices reflect incoming RF signals at different frequency shifts to encode information. This allows the system to communicate with passive devices over extended ranges without requiring high input power from the passive devices themselves, as they merely reflect signals rather than generate them. The frequency shifting parameter enables differentiation between multiple passive devices and facilitates efficient channel estimation.
2Power
If high input power is transmitted to passive devices, then energy harvesting can be achieved, but system complexity and energy loss increase
Solution Approach 1:
The patent implements feedback mechanisms where the network device transmits training sequences and receives frequency-shifted backscattered signals from passive devices. Based on the received signals, the network device estimates channel conditions and provides feedback to optimize the power allocation and transmission parameters. This feedback loop enables the system to achieve efficient energy transfer by adapting to actual channel conditions rather than using fixed high power levels, thereby reducing unnecessary energy loss.
3Measurement precision
If channel estimation is performed using conventional methods, then channel information can be obtained, but accuracy is insufficient for efficient power transfer to passive devices
Solution Approach 1:
The patent applies preliminary action by having the network device transmit training sequences before actual data transmission or power transfer operations. These training sequences are specifically designed to elicit frequency-shifted backscattered responses from passive devices, allowing the network device to pre-estimate channel conditions. This preliminary channel estimation enables subsequent optimized power allocation and transmission parameter selection, improving overall system efficiency without requiring complex real-time estimation during active transmission.
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 improves the energy harvesting efficiency and range for passive IoT devices by accurately estimating channel state information through backscattering, enabling more effective power transfer and communication with RFID tags, even at lower input powers.
Implementation Method 1
receive, from each passive device of the group of passive devices, at least one backscatter signal, based on the CW signal, at a respective frequency shift
Data Source
AI summary
Disclosed are systems, apparatuses, processes, and computer-readable media for wireless communications. For example, a network device can transmit, to a group of passive devices, a continuous wave (CW) signal. The network device can receive, from each passive device of the group of passive devices, at least one backscatter signal, based on the CW signal, at a respective frequency shift. The network device can estimate, based on the at least one backscatter signal, channel information for each passive device of the group of passive devices. The network device can then determine, based on the channel information, a channel for transmitting an energy signal to at least one passive device of the group of passive devices for energy harvesting.