Vehicle Authorization Using Spatial Field Angle Detection

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Solution Overview

Problem

Existing methods for authorizing the use of motor vehicles are vulnerable to tampering and manipulation, lacking effective protection against such threats.

Innovation Solution

A method utilizing two spatially separated antennas and an identification transmitter with an angle-resolving magnetic field sensor to determine the spatial components of electromagnetic fields, ensuring that only if the angle between these components exceeds a predetermined threshold is an authorization signal provided, thereby preventing manipulation of the radio link.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If a portable identification transmitter is used for vehicle authorization, then the authorization process becomes more convenient, but the system becomes vulnerable to manipulation and replay attacks

Engineering Contradiction:
Improveauthorization convenienceVSAvoidmanipulation resistance
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The patent transitions from simple signal presence detection to spatial dimension analysis by determining the angle between electromagnetic field vectors from multiple antennas. This angular information adds a new dimension to the authorization verification, making replay attacks ineffective because the angular relationship cannot be replicated by simple signal repetition.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The system continuously monitors the angular relationship between signals received at multiple antennas and compares it against expected geometric relationships. This feedback mechanism detects manipulation attempts by identifying deviations from the expected angular patterns that would occur with legitimate transmitters versus replayed signals.

Inventive Principle:
Principle #23Feedback

2Reliability

If multiple spatially separated antennas are used to determine signal angles, then manipulation detection capability is improved, but the device complexity increases

Engineering Contradiction:
Improvemanipulation detectionVSAvoidantenna and sensor system complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The identification transmitter serves multiple functions: it transmits identification signals for authorization and simultaneously acts as a source for angular position determination. The same transmitted signal is used for both authentication and spatial verification, eliminating the need for separate sensing systems and reducing overall complexity.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The system uses its own transmitted signals to determine angular relationships rather than requiring external reference signals or additional dedicated sensing hardware. The identification transmitter's own emissions are analyzed by the vehicle's antenna system to compute angular positions, making the system self-sufficient.

Inventive Principle:
Principle #25Self-service

3Reliability

If angular resolution is used to detect signal manipulation, then security against replay attacks is improved, but the measurement precision requirements increase

Engineering Contradiction:
Improvereplay attack detectionVSAvoidangular measurement accuracy
Core Design Contradiction:
ReliabilityVSMeasurement precision

Solution Approach 1:

The angular measurement is decomposed into discrete angular intervals or sectors rather than requiring continuous high-precision measurements. By segmenting the angular space into zones, the system achieves sufficient discrimination between legitimate and manipulated signals without demanding extreme measurement precision.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The system changes the evaluation parameter from requiring high-precision absolute angular measurements to evaluating relative angular relationships and geometric consistency. This parameter transformation reduces the stringent precision requirements while maintaining the ability to detect manipulation through geometric verification.

Inventive Principle:
Principle #35Parameter changes

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 method enhances security by detecting and preventing manipulation attempts, ensuring the integrity of the authorization process and reducing the risk of unauthorized access.

Implementation Method 1

the identification transmitter determines at least one of the spatial components of the first electromagnetic field of the received first signal, preferably using an angle-resolving magnetic field sensor

Methodology Applied
Scientific EffectMagnetic field sensing: Magnetic Field

Data Source

PatentEP3433139B1Authorizing the use of a motor vehicle
Publication Date: 2021.05.26 BAYERISCHE MOTOREN WERKE AG

AI summary

Method for authorizing the use of a motor vehicle which has at least a first and a second antenna, wherein the antennas are arranged spaced apart spatially from one another, by means of a portable identification signal generator which has an identification signal generator antenna. In order to improve the protection against tampering, the first vehicle antenna outputs a first signal which is received by the identification signal generator antenna. The identification signal generator determines at least one of the spatial components of the first electromagnetic field of the received first signal. The second vehicle antenna outputs a second signal which is received by the identification signal generator antenna. The identification signal generator determines at least one of the spatial components of the second electromagnetic field of the received second signal. The identification signal generator transmits the data to the vehicle. A computer determines the angle at least between the special components of the signals.