Interference-Avoiding Phase-Based Distance Measurement
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Solution Overview
Problem
Time-of-flight (ToF) distance measurement between wireless devices is hindered by interference from Wi-Fi signals, which distort Bluetooth Low Energy (BLE) signals due to overlapping frequency spectrums, leading to poor phase accuracy in distance calculations.
Innovation Solution
A system that identifies occupied Wi-Fi channels and constructs a channel plan using undistorted BLE channels to perform phase-based ranging, ensuring accurate distance measurements by avoiding interference, which involves scanning the BLE spectrum, identifying unusable channels due to strong Wi-Fi signals, and reallocating measurements across unoccupied channels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If phase-based ranging is performed using all available BLE channels, then measurement precision is improved, but reliability deteriorates due to Wi-Fi interference on overlapping channels
Solution Approach 1:
The patent segments the BLE channel spectrum into two categories: channels affected by Wi-Fi interference and channels not affected by Wi-Fi interference. The controller identifies which channels are occupied by Wi-Fi signals and separates them from the channels suitable for phase-based ranging measurements. This segmentation allows the system to selectively use only the clean, interference-free channels for measurements, thereby maintaining measurement precision while ensuring reliability by avoiding corrupted channels.
2Reliability
If the system avoids channels with Wi-Fi interference, then reliability is improved, but measurement precision deteriorates due to reduced number of usable channels
Solution Approach 1:
The patent changes the parameter of channel selection dynamically based on the detected Wi-Fi interference conditions. Instead of using a fixed set of BLE channels, the system adaptively adjusts which channels are used for phase-based ranging by monitoring Wi-Fi channel occupancy and selecting from the remaining interference-free channels. This parameter change allows the system to maintain reliability by avoiding corrupted channels while preserving measurement precision by utilizing the maximum available number of clean channels for the ranging calculation.
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 enhances the accuracy of BLE phase measurements by minimizing interference from Wi-Fi signals, allowing for reliable distance determination between wireless devices, such as in vehicle access systems, by using a subset or repeated scans of undistorted BLE channels.
Implementation Method 1
perform phase-based ranging using data scanned via the channel plan
Implementation Method 2
identify one or more occupied channels of a second transmission protocol, the first and second transmission protocols having overlapping frequency spectrums
Data Source
AI summary
Interference-avoiding distance measurement is provided. A controller of a first wireless device is configured for wireless communication over a first transmission protocol with a second wireless device. One or more occupied channels of a second transmission protocol are identified, the first and second transmission protocols having overlapping frequency spectrums. A channel plan is constructed according to the occupied channels, the channel plan using a set of channels of the first transmission protocol that do not overlap in frequency with the one or more occupied channels of the second transmission protocol. Phase-based ranging is performed using data scanned via the channel plan. A distance measurement is indicated based on the phase-based ranging.