Method and apparatus for security in a wireless network

• US 20050232057A1
• Filed: 02/25/2005
• Published: 10/20/2005
• Est. Priority Date: 03/05/2004
• Status: Active Grant

• Current Assignee: Seknion Incorporated
• Original Assignee: Seknion Incorporated
• Inventors: Hansen, Thorkild, Oristaglio, Michael L.
• Granted Patent: US 7,398,078 B2
• Time in Patent Office: Days
• US Class Current: 365/230.10
• CPC Class Codes: H01Q 25/02 providing sum and difference patterns H01Q25/04 takes precedence
• CPC Class Codes: H04W 12/08 Access security
• CPC Class Codes: H04W 16/28 using beam steering

Abstract

The present invention relates to an apparatus and method for preventing unauthorized users from gaining access to a wireless network. A processor allows only data transmissions from the directions of the authorized users to access the network. Data transmissions from other directions are not allowed to access the network. The present invention also relates to a method and apparatus fore transmitting information only in selected directions, while in directions not selected, information cannot be inferred from the transmitted signal or signals.

Claims

1. A method for preventing unauthorized transmitters from gaining access to a wireless network comprising the steps of:

receiving signals with an antenna system that has more than one output port,

computing a first output with a first receiving pattern that has a main beam pointed towards an authorized transmitter,

computing a second output with a second receiving pattern that has a null in the direction of said authorized transmitter and is larger in magnitude than said first receiving pattern,

computing the energy of said first output,

computing the energy of said second output, and

transmitting information contained in said first output to said network only if said energy of said first output is larger than said energy of said second output.

2. The method of claim 1, wherein said second receiving pattern is computed from a combination of one or more difference patterns.

3. The method of claim 1, wherein said first receiving pattern is computed from a combination of one or more sum patterns.

4. The method of claim 1, wherein said step of computing a first output and said step of computing a second output each comprises using beam steering.

5. The method of claim 1, wherein said step of receiving signals further comprises using one or more array antennas.

6. The method of claim 1, wherein said step of computing a first output and said step of computing a second output each comprises using analytical array synthesis techniques.

7. The method of claim 1, wherein said step of computing a first output and said step of computing a second output each comprises using iterative array synthesis techniques.

8. The method of claim 1, wherein said step of receiving signals comprises using a planar array antenna.

9. The method of claim 1, wherein said step of computing a second output comprises using cosine and sine difference patterns.

10. The method of claim 1, wherein said step of receiving signals comprises using a ring array antenna.

11. The method of claim 1, wherein said step of receiving signals comprises using a reflector antenna.

12. A method for securely transmitting data over radio waves comprising:

transmitting one or more data beams wherein each said data beam comprises data and a radiation pattern,

transmitting one or more scramble beams comprising one or more signals from which data cannot be inferred and one or more radiation patterns, and,

adjusting said one or more data beams and said one or more scramble beams such that said one or more scramble beams overshadow said one or more data beams in all but selected directions.

13. The method of claim 12, wherein at least one of said one or more scramble beams contains a separate intelligible data stream intended for one or more receivers located in directions where said one scramble beam overshadows all other beams.

14. The method of claim 12, wherein at least one of said one or more scramble beams contains an intelligible data stream that is used to convey information for one or more transceivers located in directions where said one scramble beam overshadows all other beams, wherein said information comprises information about which of said one or more transceivers will communicate using one or more data beams.

15. The method of claim 12, wherein a communication channel provided by said one or more scramble beams is used to organize a contention period.

16. The method of claim 15, wherein said contention period uses a multiple access control method.

17. The method of claim 15, wherein said one or more scramble beams organize said contention period using a binary countdown method.

18. The method of claim 12, wherein said one or more scramble beams comprise one or more difference patterns.

19. The method of claim 12, wherein said one or more data beams comprise one or more sum patterns.

20. The method of claim 12, further comprising adjusting said one or more data beams and said one or more scramble beams using beam steering.

21. The method of claim 12, further comprising transmitting said one or more data beams and transmitting said one or more scramble beams using one or more array antennas.

22. The method of claim 21, further comprising adjusting said one or more data beams and said one or more scramble beams using analytical array synthesis techniques.

23. The method of claim 21, further comprising adjusting said one or more data beams and said one or more scramble beams using iterative array synthesis techniques.

24. The method of claim 12, wherein said one or more scramble beams have approximately constant amplitudes away from a central null, and the total radiated power is approximately omni-directional.

25. The method of claim 24, wherein constant-amplitude scramble beams are achieved by moving zeros off the Schelkunoff unit circle.

26. The method of claim 24, wherein constant-amplitude scramble beams are achieved by iterative methods.

27. The method of claim 12, wherein data signal bits of one of said one or more data beams are divided into a plurality of parts.

28. The method of claim 27, wherein for each part of said plurality of parts, a corresponding scramble-beam direction is defined slightly away from the direction of said one data beam.

29. The method of claim 27, wherein each part of said plurality of parts is transmitted while a scramble beam has a central null steered in the direction of a corresponding scramble-beam direction.

30. The method of claim 12, wherein the spatial dependences of said one or more data beams and said one or more scramble beams are indistinguishable away from a null of one of said one or more scramble beams.

31. The method of claim 12, further comprising transmitting said one or more data beams and said one or more scramble beams using a planar array antenna.

32. The method of claim 31, further comprising transmitting said one or more scramble beams using cosine and sine difference patterns.

33. The method of claim 12, further comprising scanning one or more secure data beams in angular increments using beam steering while transmitting at each said angular increment a unique identification number identifying and locating transceivers within range.

34. The method of claim 33, further comprising using said unique identification number to create and store a table indicating the current positions and signal strengths of transceivers within range.

35. The method of claim 33, wherein said transceivers are RFID tags.

36. The method of claim 33, wherein said transceivers are laptop computers.

37. The method of claim 33, wherein said transceivers are mobile phones.