Backscatter Frequency Alignment for Interference Mitigation
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Solution Overview
Problem
Backscatter devices face interference issues due to the higher power illuminating signal used for RF carrier generation, which affects the reception of backscatter transmission, particularly in monostatic and bistatic scenarios.
Innovation Solution
A method for a simultaneous transmission and reception multi-link device (MLD) that transmits a signal packet with control information for backscatter transmission, including a frequency indicator to align the backscatter transmission within the reception channel, and uses OFDM signaling to mitigate interference by coinciding with OFDM signal sub-carriers or applying a frequency shift.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If an illuminating node transmits RF carrier signal at higher power for backscatter transmission, then the backscatter device can perform transmission without generating its own RF carrier (reducing power consumption), but the illuminating signal causes interference to the backscatter transmission reception
Solution Approach 1:
The patent segments the frequency spectrum into different channels: a transmission channel for the illuminating signal and a reception channel for backscatter transmission. By separating these functions across different frequency channels, the system allows the illuminating node to transmit at high power while the backscatter device receives on a different channel, thereby reducing interference. The control information carries frequency indicators that guide the backscatter device to use specific reception channels distinct from the illuminating signal channel.
Solution Approach 2:
The patent introduces control information as an intermediary mechanism that carries frequency indicator data from the illuminating node to the backscatter device. This intermediary allows the backscatter device to be informed about the illuminating signal's frequency characteristics and adjust its reception settings accordingly, enabling it to avoid interference while still utilizing the illuminating signal for power and carrier generation.
2Productivity
If the illuminating node is also receiving the backscatter transmission (monostatic scenario), then system resources are utilized efficiently, but the illuminating signal transmitted with higher power interferes with the backscatter transmission reception
Solution Approach 1:
In the monostatic scenario where the illuminating node also receives backscatter transmissions, the patent applies frequency channel segmentation to separate transmitting and receiving operations. The illuminating node transmits on a transmission channel while receiving on a reception channel, allowing simultaneous operations without self-interference. The control information mechanism ensures the backscatter device knows which reception channel to use, maintaining reliable communication while efficient resource utilization.
3Adaptability or versatility
If the backscatter transmission frequency is aligned with OFDM signal sub-carriers, then the backscatter transmission can be received by existing OFDM transceivers (coexistence with legacy systems), but the illuminating signal interference is intensified
Solution Approach 1:
The patent segments frequency resources by having the backscatter transmission occur on specific OFDM sub-carriers that are distinct from the illuminating signal's frequency occupation. The control information provides frequency indicators that guide the backscatter device to transmit on sub-carriers allocated for reception, allowing legacy OFDM transceivers to receive the backscatter signal while the illuminating signal occupies different frequency resources, thus reducing interference.
Solution Approach 2:
The patent applies local quality differentiation by assigning specific sub-carriers or frequency bands to specific functions: some sub-carriers are designated for illuminating signal transmission while others are designated for backscatter reception. This localized frequency allocation allows the backscatter transmission to coincide with OFDM sub-carriers for legacy compatibility while avoiding the illuminating signal's frequency domain, thereby balancing coexistence with interference avoidance.
Data Source
AI summary
A method is disclosed for a simultaneous transmission and reception (STR) multi-link device (MLD). The method includes transmitting a signal packet within a transmission channel of the MLD for illumination of a backscatter device. The signal packet includes control information regarding backscatter transmission, and the control information includes a frequency indicator for backscatter transmission. The frequency indicator for backscatter transmission is configured to cause the backscatter transmission to fall within a reception channel of the MLD. A method is also disclosed for a backscatter device. The method includes receiving the signal packet from the STR MLD within a transmission channel of the MLD, whereby the signal packet illuminates the backscatter device, and performing backscatter transmission in accordance with the frequency indicator for backscatter transmission, whereby the backscatter transmission falls within a reception channel of the MLD.