Method and apparatus for an anti-theft system against radio relay attack in passive keyless entry/start systems

• US 7,791,457 B2
• Filed: 12/15/2006
• Issued: 09/07/2010
• Est. Priority Date: 12/15/2006
• Status: Active Grant

• Current Assignee: Lear Corporation
• Original Assignee: Lear Corporation
• Inventors: Ghabra, Riad, King, Ronald O., Luo, Yi, Nantz, John
• Primary Examiner(s): Lee; Benjamin C
• Assistant Examiner(s): BEE, ANDREW W.
• Application Number:
  US11/639,915
• Publication Number:
  US 20080143500A1
• Time in Patent Office: 1,362 Days
• Field of Search: 340/426.36, 340/5.61
• US Class Current: 340/426.36
• CPC Class Codes: B60R 25/24 using electronic identifiers containing a code not memorised by the user
• CPC Class Codes: G07C 2009/00555 comprising means to detect or avoid relay attacks
• CPC Class Codes: G07C 2009/00793 by Hertzian waves
• CPC Class Codes: G07C 9/00309 operated with bidirectional data transmission between data carrier and locks

Abstract

An apparatus and method is provided for identifying unauthorized access to a vehicle having a keyless-passive entry system. An interrogation signal is broadcast from a vehicle based transmission device. The interrogation signal includes a first pulse transmitted at a first amplitude and a second pulse transmitted at a second amplitude where the second amplitude is greater than the first amplitude by at least a predetermined difference threshold. The interrogation signal is received by a portable communication device. A determination is made whether the second amplitude of the second pulse is greater than the first amplitude of the first pulse by a predetermined difference threshold. A determination is made that the interrogation signal is an authorized interrogation signal in response to the determination that the interrogation signal includes the first pulse transmitted at the first amplitude following by the second pulse transmitted at the second amplitude where the second amplitude is greater than the first amplitude by at least a predetermined difference threshold.

Claims

1. A method for identifying unauthorized access to a vehicle having a keyless-passive entry system, the method comprising the steps of:

broadcasting an interrogation signal from a vehicle based transmission device of the keyless-passive entry system, the interrogation signal having a first pulse transmitted at a first amplitude and a second pulse transmitted at a second amplitude where the second amplitude is greater than the first amplitude by at least a predetermined difference threshold;

receiving the interrogation signal by a portable communication device of the keyless-passive entry system;

determining, by the portable communication device if the second amplitude of the second pulse is greater than the first amplitude of the first pulse by at least the predetermined difference threshold; and

determining, by the portable communication device that the interrogation signal is an authorized interrogation signal in response to the determination that the received interrogation signal includes the first pulse transmitted at the first amplitude followed by the second pulse transmitted at a second amplitude where the second amplitude is greater than the first amplitude by at least a predetermined difference threshold.

2. The method of claim 1 wherein the step of receiving the interrogation signal by the portable communication device further includes the steps of measuring a relative amplitude of the first pulse, waiting for a predetermined period of time, and measuring a relative amplitude of the second pulse.

3. The method of claim 1 wherein the portable communication device is non-responsive to the interrogation signal if the second amplitude of the second pulse is not greater than the first amplitude of the first pulse by at least the predetermined threshold difference.

4. The method of claim 3 wherein the interrogation signal further includes data, the portable communication device determining the validation of the data within the interrogation signal.

5. The method of claim 4 wherein the portable communication device is non-responsive to the interrogation signal in response to the determination that the data within the interrogation signal is invalid.

6. The method of claim 4 wherein determining the validation of the data within the interrogation signal is performed after the determination is made that the second amplitude of the second pulse is greater than the first amplitude of the first pulse by at least the predetermined difference threshold.

7. The method of claim 4 wherein determining the validation of the data within the interrogation signal is performed concurrently with the determination of whether the second amplitude of the second pulse is greater than the first amplitude of the first pulse by at least the predetermined difference threshold.

8. The method of claim 4 wherein determining the validation of the data within the interrogation signal is performed prior to the determination of whether the second amplitude of the second pulse is greater than the first amplitude of the first pulse by at least the predetermined difference threshold.

9. The method of claim 1 further comprising the steps of broadcasting a response signal if a determination is made that the second amplitude of the second pulse is greater than the first amplitude of the first pulse by at least the predetermined difference threshold.

10. The method of claim 9 further comprising the steps of enabling access to the vehicle in response to receiving an authenticated response signal from the portable communication device.

11. The method of claim 1 wherein said interrogation signal comprises a low frequency signal.

12. The method of claim 1 wherein the first pulse and the second pulse are preceded by data pulses transmitted within the interrogation signal.

13. The method of claim 1 wherein the interrogation signal includes an intermediate pulse transmitted between the first pulse and the second pulse, wherein the portable communication device determines if an amplitude of the intermediate pulse is greater than the first amplitude of a first pulse by at least a second predetermined difference threshold.

14. The method of claim 13 wherein the portable communication device determines if the second amplitude of the second pulse is greater than the amplitude of the intermediate pulse by at least the second predetermined difference threshold.

15. The method of claim 1 wherein the interrogation signal includes a plurality of intermediate pulses transmitted between the first pulse and the second pulse, wherein the portable communication device determines if the amplitude of each respective intermediate pulse has an amplitude greater than a respective amplitude of a respective previous pulse by a second predetermined difference threshold.

16. A keyless-passive entry system for identifying unauthorized access to a vehicle, the system comprising:

a portable communication device carried by a user of a vehicle for accessing entry to the vehicle;

a vehicle based transmission device in communication with the portable communication device;

an interrogation signal broadcast by the vehicle based transmission device as a low frequency signal, the interrogation signal having a first pulse transmitted at a first amplitude followed by a second pulse transmitted at a second amplitude, the second amplitude is greater than the first amplitude by a predetermined difference threshold, the portable communication device receiving the interrogation signal broadcast from the vehicle based communication device, the portable communication device determines the interrogation signal is an authorized interrogation signal in response to a determination that the second amplitude of the second pulse is greater than the first amplitude of the first pulse by at least the predetermined difference threshold.

17. The keyless-passive entry system of claim 16 wherein the portable communication device includes a controller.

18. The keyless-passive entry system of claim 16 wherein the interrogation signal includes a delay between the first pulse transmitted at the first amplitude and the second pulse transmitted at the increased second amplitude.

19. The keyless-passive entry system of claim 16 wherein the first pulse and the second pulse include non-data pulses.

20. The keyless-passive entry system of claim 16 wherein the first pulse and the second pulse include data.