Semi-Passive Transponder for Vehicle Access Control
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Solution Overview
Problem
Existing access control systems for vehicles face issues such as limited battery life in key fobs, inadequate protection against relay attacks, higher system costs due to multiple frequencies, and user inconvenience with backup facilities, while also being vulnerable to relay attacks and having restricted communication ranges.
Innovation Solution
The access control system employs a semi-passive transponder using a rechargeable energy storage means, operating at a single frequency of 13.56 MHz for bidirectional communication, with the ability to switch to semi-active or passive modes for extended communication range and protection against relay attacks, utilizing a rotating three-dimensional magnetic field and broadband spectrum protocols for enhanced security and convenience.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If battery-operated key fobs are used for active transponder communication, then communication range and data transmission capability are improved, but battery life is limited and requires backup facilities
Solution Approach 1:
The transponder operates in periodic active and passive modes. The control device sends wake-up signals at specific intervals, and the transponder activates only during these periods to transmit authentication data, then returns to passive state. This periodic operation dramatically reduces energy consumption while maintaining communication capability when needed.
Solution Approach 2:
The transponder is designed to be self-sufficient by switching between active and passive modes based on received signals. When energy is available from the rechargeable storage means, it operates actively; when energy is low or unavailable, it automatically switches to passive operation, eliminating the need for external backup facilities and user intervention.
2Reliability
If multiple frequencies are used for data transmission and wake-up functions, then communication reliability is improved, but system costs increase
Solution Approach 1:
The transponder is designed with multi-functional capability to operate at both the first frequency (for wake-up signals) and the second frequency (for data transmission). This universal design eliminates the need for separate dedicated hardware for each frequency, reducing system complexity and costs while maintaining the reliability benefits of multi-frequency operation.
Solution Approach 2:
The patent combines the wake-up function and data transmission function into a single integrated transponder system that can handle both frequencies. By merging these functions into one device rather than using separate systems, the overall system complexity and cost are reduced while maintaining communication reliability.
3Device complexity
If transponders operate in passive mode only, then system simplicity is maintained, but communication range is restricted
Solution Approach 1:
The transponder employs dynamic operation mode switching between passive and active states. In passive mode, it maintains system simplicity and low power consumption. When wake-up signals are detected and energy is available from the rechargeable storage means, it dynamically transitions to active mode to extend communication range for authentication data transmission, then returns to passive mode.
4Ease of operation
If conventional access control systems are used, then basic authentication is provided, but protection against relay attacks is inadequate
Solution Approach 1:
The control device and transponder implement a challenge-response authentication protocol with feedback mechanisms. The control device sends challenge signals, the transponder responds with authenticated data, and the system verifies the response. This feedback loop ensures that relay attacks are detected and blocked, as the authentication process requires direct communication between the legitimate transponder and control device.
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 provides extended communication range, improved security against relay attacks, reduced system costs, increased user convenience, and reliable backup functionality, eliminating battery life limitations and enabling seamless vehicle starting without manual intervention.
Implementation Method 1
an electronic control unit assigned to the vehicle, which is usually permanently supplied with energy, and the mobile identification devices... The rechargeable energy storage means can comprise at least one rechargeable battery
Implementation Method 2
two frequencies are used, one for data transmission and the wake-up function from the vehicle, and one for data transmission from the identification device back to the vehicle... bidirectional wireless communication between the access-side control device and the user-side identification device
Implementation Method 3
utilizing a rotating three-dimensional magnetic field and broadband spectrum protocols for enhanced security and convenience
Data Source
AI summary
An access control system, particularly for vehicles, comprises an access-side control unit, a user-side identification unit, and a transceiver assigned to the control unit for bidirectional wireless communication with the identification unit. The user-side identification unit is assigned at least one, preferably sequential, transponder for bidirectional wireless communication with the access-side control unit. In a first operating state of the identification unit, this transponder is powered by a non-rechargeable battery integrated into the identification unit.Furthermore, means preferably associated with the identification device for monitoring the state of the non-rechargeable battery, as well as means to switch the identification device to a second operating state when a predefinable battery discharge state is reached, in which the transponder associated with the identification device can be operated semi-passively by being supplied with energy via the access-side control device and its transmission power is increased, in particular for so-called active communication, by means of rechargeable energy storage means.