Antenna Switching for AOA Capture in Phone-as-a-Key Access
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Solution Overview
Problem
Traditional passive entry/passive start (PEPS) systems using low-frequency signals face limitations in range and reliability due to long wavelengths, and are vulnerable to wireless attacks such as eavesdropping and replay attacks, making it difficult to securely communicate with key fobs beyond a few meters and compromising vehicle access security.
Innovation Solution
A portable access device with a transceiver and control module that uses 2.4 GHz radio frequency signals to establish a communication link with a vehicle's phone-as-a-key (PaaK) system, incorporating de-whitened packets and queue management to enhance security and range, while preventing unauthorized access through cryptographic verification and angle-of-arrival determination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If low frequency signals are used for PEPS communication, then accurate range and location estimation can be achieved, but communication range is limited to a few meters
Solution Approach 1:
The patent combines LF and HF communication systems into a unified PEPS system. The LF transceiver provides accurate range and location estimation, while the HF transceiver extends communication range. Both systems work together to overcome the limitations of using either system alone, enabling both precise measurement and long-range communication.
Solution Approach 2:
The patent introduces an intermediary relationship where the LF system provides measurement data that complements the HF system's long-range capability. The control module acts as an intermediary that processes signals from both transceivers and coordinates their functions to achieve both accurate estimation and extended range.
2Length of moving object
If smart devices communicate at high RF frequencies, then communication range is extended, but vulnerability to wireless attacks increases
Solution Approach 1:
The patent implements preliminary anti-action by using LF signals for authentication and authorization before allowing HF communication. The LF system's inherent security properties (accurate range estimation, difficulty of relay attacks) are used to verify the legitimate user first, then the HF system is activated for extended range communication. This preemptive security measure prevents unauthorized access before it can occur.
Solution Approach 2:
The patent changes the operational parameters of the communication system by switching between LF and HF frequencies based on security requirements. LF is used for secure authentication phase, then HF is activated for data transmission phase. This parameter change allows the system to leverage the security strengths of LF while achieving the range benefits of HF.
3Use of energy by moving object
If LF signals are transmitted at safe power levels, then power consumption is controlled, but reliable communication beyond a few meters is difficult
Solution Approach 1:
The patent makes the PEPS system multi-functional by equipping it with both LF and HF transceivers. The LF transceiver handles authentication and close-range communication with low power consumption, while the HF transceiver handles long-range communication when needed. This universality allows the system to maintain low power consumption for routine operations while having the capability to extend range when necessary.
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
The solution enables secure, long-range communication with vehicles, enhances security by preventing unauthorized access, and maintains reliable vehicle access functions beyond the limitations of traditional LF systems, addressing vulnerabilities in existing PEPS systems.
Implementation Method 1
smart devices communicate at high radio frequencies (RFs) and thus are able to communicate over longer distances than LF systems
Implementation Method 2
Strengths of signals received via multiple vehicle antennas may be monitored to estimate the location of the key fob relative to the vehicle
Data Source
AI summary
A reader includes a transceiver and a control module. The transceiver is configured to, during a current connection event, monitor notification messages transmitted from a portable access device to a phone-as-a-key (PaaK) system of a vehicle, where the notification messages are transmitted to establish a communication link between the portable access device and the PaaK system. The control module is configured to: perform an in-phase and quadrature phase capture of the notification messages based on fields in one or more of the notification messages, where the fields include a mobile de-whitened section including two or more series of consecutive bits, where the consecutive bits in each of the one or more series are all zeros or all ones; based on the in-phase and quadrature phase capture, determine an angle-of-arrival of the notification messages, and indicate the angle-of-arrival to the PaaK system for permitted access determined by the PaaK system.