Backscatter Frequency Offset Control for Wi-Fi Collision Avoidance
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Solution Overview
Problem
Current solutions fail to address the interference of backscatter devices (BKDs) with neighboring Wi-Fi devices due to their unscheduled transmissions at any time, which can disrupt Wi-Fi environments without performing clear channel assessment or waiting for instructions.
Innovation Solution
Implementing a method where an access point (AP) transmits a frame to a BKD using a first frequency, including a parameter to adjust the BKD's frequency filter, allowing the BKD to transmit a reply message on a different second frequency, and the AP receives the reply message using this adjusted frequency, thereby reducing interference by directing BKDs to use unused frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If BKD transmits at any time when energy storage device has enough energy, then BKD can function autonomously without waiting for instructions, but BKD transmission interferes with neighboring Wi-Fi devices transmissions
Solution Approach 1:
The patent changes the frequency parameter of BKD transmissions by introducing a frequency offset from the received Wi-Fi signal. The BKD receives signals at frequency f1 and transmits reply messages at frequency f2 = f1 + offset, where the offset is determined by the AP. This parameter change allows BKDs to maintain autonomous transmission while operating on different frequencies that do not interfere with neighboring Wi-Fi devices.
2Loss of time
If BKD transmits without performing clear channel assessment, then BKD transmission response time is reduced, but BKD transmission causes collisions in the Wi-Fi environment
Solution Approach 1:
The patent moves BKD transmissions from the same frequency dimension as Wi-Fi signals to a different frequency dimension by applying a frequency offset. This dimensional separation allows BKDs to transmit immediately without CCA on the original Wi-Fi channel while the offset frequency carries their reply messages, eliminating collisions while preserving fast response time.
3Device complexity
If BKD uses the same frequency for receiving and transmitting, then communication simplicity is maintained, but transmission interference with Wi-Fi channels occurs
Solution Approach 1:
The patent modifies the transmission frequency parameter by introducing a configurable offset from the received signal frequency. The AP determines this offset and communicates it to the BKD, which then uses this offset to calculate its transmission frequency. This parameter change resolves the interference issue while maintaining relatively simple communication protocols.
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 minimizes collisions and interference by controlling the transmission frequency of BKDs, ensuring their communications do not overlap with existing Wi-Fi channels, thus enhancing network stability and efficiency.
Implementation Method 1
the BKD is entirely passive, and merely reflects (thus in real time) the energy
Implementation Method 2
the parameter includes a frequency offset that adjusts a frequency filter in the BKD
Data Source
AI summary
Embodiments herein describe BKDs that can transmit reply messages using different frequencies than the frequencies of wireless transmissions they receive which can reduce collisions in a Wi-Fi environment. In one embodiment, when transmitting power to be used by a BKD to transmit a reply message, an access point (AP) also includes an parameter that affects the frequency used by the BKD when transmitting its signal. For example, the AP can direct the BKD to use a frequency in a channel that is not used by other Wi-Fi Devices. The BKD can be equipped with a frequency filter that can shift the carrier frequency of the BKD response (compared to the carrier frequency of the energy-bearing signal) allowing the response signal to be transmitted on a different frequency than the one which was received.