BLE Angle of Arrival Measurement Using Phase Difference
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Solution Overview
Problem
Passive entry/passive start (PEPS) systems using low-frequency signals face limitations in accurately determining the location and angle of arrival of key fobs beyond a few meters due to the long wavelength of LF signals, restricting the range of vehicle function availability.
Innovation Solution
A method and system utilizing Bluetooth Low Energy (BLE) signals, where antennas receive and process packets to determine the angle of arrival by generating digital data sets from multiple antennas, obtaining cosine and sine components, and calculating phase angle values to accurately measure the angle of arrival, enabling longer-range communication and vehicle function access.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If low-frequency signals are used for PEPS systems, then signal propagation allows for relatively accurate estimation of range and location by using signal strength, but the extremely long wavelength makes it difficult to reliably communicate with a key fob beyond a few meters
Solution Approach 1:
The patent changes the frequency parameter from low-frequency (LF) to high-frequency (HF) signals. This parameter change enables both extended communication range and maintained angle of arrival measurement accuracy, resolving the contradiction between measurement precision and communication range by transitioning to a different frequency band that provides superior propagation characteristics.
2Reliability
If traditional LF systems are used, then key fob authentication works within typical activation range, but the system cannot provide long-range distancing features
Solution Approach 1:
The patent changes the signal frequency parameter from LF to HF, enabling the system to maintain reliable key fob authentication while extending the activation range beyond the traditional LF limitation of a few meters to support long-range distancing features.
Solution Approach 2:
The patent replaces the traditional LF-based PEPS system with a HF-based system that uses angle of arrival measurements from multiple antennas. This substitution enables both reliable authentication and extended range by using a different physical approach (phase difference measurement across multiple antennas instead of single-point LF signal strength measurement).
3Measurement precision
If angle of arrival measurement is implemented using traditional methods, then location estimation is possible, but the measurement precision deteriorates beyond a few meters due to signal wavelength characteristics
Solution Approach 1:
The patent changes the frequency parameter from LF to HF, which fundamentally improves angle of arrival measurement precision across extended ranges. The shorter wavelength of HF signals provides better spatial resolution for phase difference measurements, enabling accurate angle measurement well beyond the few-meter limitation of LF systems.
Solution Approach 2:
The patent replaces traditional single-point signal strength-based location estimation with a multi-point phase difference measurement system. By using multiple antennas and measuring phase differences in the received signal, the system achieves superior angle of arrival measurement precision that maintains accuracy over extended ranges.
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
Enables accurate determination of the angle of arrival for BLE signals, allowing for extended range vehicle function access and improved PEPS system performance beyond the limitations of traditional LF systems.
Implementation Method 1
receiving, using a plurality of antennas, a wireless signal comprising a packet
Data Source
AI summary
A system and method are disclosed and include receiving a wireless signal. The method includes generating a first and second set of digital data that are representative of the wireless signal. The method includes obtaining a first and second sample that is representative of a cosine and sine component, respectively, of a pre-known portion of the first set. The method includes obtaining a third and fourth sample that is representative of a cosine and sine component, respectively, of a pre-known portion of the second set. The method includes determining a first phase angle value based on an amplitude of the first and second samples and a second phase angle based on an amplitude of the third and fourth samples. The method includes determining an angle of arrival based on a difference between the first and second phase angle values.