PEPS Time-of-Arrival Ranging for Relay Attack Prevention
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional passive entry/passive start (PEPS) systems are susceptible to range extender type relay station attacks, where an attacker uses a relay device to deceive the vehicle into thinking the key fob is nearby, leading to unauthorized access.
Innovation Solution
The proposed access system uses a combination of RF signals and antenna diversity to accurately determine the location and distance of a portable access device relative to the vehicle, employing techniques such as carrier phase based ranging and polarization diversity to prevent relay attacks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional PEPS systems use signal strength for location determination, then the system is simple to operate, but the system becomes vulnerable to relay attacks where attackers can extend the effective range
Solution Approach 1:
The patent changes the measurement parameter from signal strength (RSSI) to signal time of arrival (TOA) and carrier phase. This parameter change makes relay attacks detectable because the time and phase measurements reveal the true physical distance, preventing attackers from extending the effective range while maintaining system operation
Solution Approach 2:
The patent introduces an intermediary measurement approach using carrier phase information as a mediator between the key fob and vehicle. By measuring phase differences of modulated signals, the system can determine precise distance without requiring complex hardware changes, resolving the contradiction between security and complexity
2Measurement precision
If the system uses up-sampling and cross-correlation for TOA determination, then the measurement precision is improved, but the processing time and computational complexity increase
Solution Approach 1:
The patent applies preliminary up-sampling of the received signal before cross-correlation processing. By pre-processing the signal to increase its sampling rate, the system achieves higher TOA measurement precision without requiring excessively long processing times during the critical authentication phase
Solution Approach 2:
The patent uses selective up-sampling only for the critical portions of the signal where TOA determination is needed, rather than processing entire data streams at high resolution. This partial application of high-precision processing maintains measurement accuracy while limiting computational overhead and processing time
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 solution effectively prevents range extender type relay station attacks by ensuring accurate determination of the access device's location and distance, thereby securing vehicle access and preventing unauthorized entry.
Implementation Method 1
a receiver to receive a signal transmitted from a portable access device to the vehicle
Implementation Method 2
employing techniques such as carrier phase based ranging and polarization diversity to prevent relay attacks
Implementation Method 3
determine a round trip time of the signal received by the receiver
Implementation Method 4
employing techniques such as carrier phase based ranging and polarization diversity to prevent relay attacks
Data Source
AI summary
A system is provided and includes a receiver and an access module. The receiver is configured to receive a signal transmitted from a portable access device to a vehicle. The access module is configured to generate a differentiated signal based on the received signal, up-sample the differentiated signal to generate a first up-sampled signal, up-sample an expected signal to generate a second up-sampled signal, cross-correlate the first up-sampled signal and the second up-sampled signal to generate a cross-correlation signal, determine, based on the cross-correlation signal, a phase difference between the first up-sampled signal and the second up-sampled signal, determine a round trip time of the signal received by the receiver based on the phase difference, and permit access to the vehicle based on the round trip time.