Vehicle Field Superposition Antenna System for Relay Attack Prevention
Solution Overview
Problem
Wireless communication systems, such as those used in automotive applications for passive keyless entry and ignition, are vulnerable to relay attacks where attackers can intercept and relay signals between a transponder and a base station, allowing unauthorized access or ignition of vehicles.
Innovation Solution
Implementing field superposition circuits using interior and exterior antennas, where the antennas are driven with the same phase and multiplied by superposition factors based on detected vector components, to authenticate the transponder by verifying that the received superposed signal is within an error-tolerant range of the sum of the separate vector components, thereby preventing relay attacks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single antenna is used for wireless communication between base station and transponder, then the device complexity is reduced, but the system becomes vulnerable to relay attacks and security is compromised
Solution Approach 1:
The system divides the single antenna function into multiple separate antennas (first antenna and second antenna). Each antenna transmits a separate signal that is obscured by the vehicle body, making it difficult for relay attacks to capture and reproduce the complete authentication signal pattern.
Solution Approach 2:
The patent introduces a spatial dimension to the authentication process by using multiple antennas positioned at different locations relative to the vehicle body. The transponder must receive signals from multiple spatial directions simultaneously, creating a multi-dimensional authentication challenge that relay attacks cannot replicate.
2Reliability
If multiple antennas with field superposition are implemented, then relay attacks are prevented and security is enhanced, but the device complexity and signal processing requirements increase
Solution Approach 1:
The patent combines signals from multiple antennas through field superposition, where the separate signals from the first and second antennas are merged into a composite electromagnetic field that the transponder receives and processes as a unified authentication signal.
Solution Approach 2:
The system implements feedback by having the transponder measure and report back the combined signal strength from multiple antennas. The base station uses this feedback to verify that the transponder is receiving signals from the correct spatial configuration, preventing relay attacks that cannot reproduce the exact signal superposition pattern.
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
Enhances security by ensuring that only a valid transponder in proximity to the vehicle can authenticate, effectively preventing unauthorized access or ignition, and mitigates relay attacks by generating a signal that is difficult to replicate without replicating the vehicle structure.
Implementation Method 1
Interior and exterior antennas are driven using first driving currents... Separate vector components of the respective fields that are emitted by the interior and exterior antennas and received at the transponder
Implementation Method 2
the interior antenna being separated from the transponder by a portion of a vehicle in which the vehicle base station resides
Data Source
Figure 1
Figure 2
Figure 3
AI summary
Wireless communications between a vehicle base station and a transponder are authenticated. Interior and exterior antennas are respectively driven using first driving currents, the interior antenna being separated from the transponder by a portion of a vehicle in which the vehicle base station resides. Separate vector components of the respective fields emitted by the interior and exterior antennas are received and detected at the transponder. Superposition factors are calculated for the interior and exterior antennas based upon the separate vector components. Each of the interior and exterior antennas is concurrently driven using the same phase, respectively using the driving currents multiplied by the superposition factors. Superposed vector components are detected for a superposed signal including signals from both antennas received at the transponder. The transponder is authenticated based on the detected superposed vector components for the superposed signal being within a noise-based range of the sum of the separate vector components for each of the interior and exterior antennas as multiplied respectively by the superposition factors for the interior and exterior antennas.