Waveform collection for use in wireless telephone identification

• US 5,999,806 A
• Filed: 02/28/1997
• Issued: 12/07/1999
• Est. Priority Date: 02/28/1997
• Status: Expired due to Fees

• Current Assignee: Cellular Technical Services Co., Inc. (Asensus Surgical, Inc.)
• Original Assignee: Cellular Technical Services Co., Inc. (Asensus Surgical, Inc.)
• Inventors: Kaplan, Dmitry, Stanhope, David M.
• Primary Examiner(s): Bost, Dwayne D.
• Assistant Examiner(s): GELIN, JEAN ALLAND
• Application Number:
  US08/808,630
• Time in Patent Office: 1,012 Days
• Field of Search: 455/410, 455/411, 455/412, 455/414, 455/428, 455/434, 455/435, 455/445, 455/32.1, 455/67.1, 455/405, 455/423, 380/23, 380/25, 340/825.44, 340/825.15, 379/189
• US Class Current: 455/411
• CPC Class Codes: H04W 12/08 Access security
• CPC Class Codes: H04W 12/126 Anti-theft arrangements, e.g. protection against subscriber identity module [SIM] cloning
• CPC Class Codes: H04W 12/79 Radio fingerprint

Abstract

A system and method for collecting reference waveforms from authorized wireless telephones in a wireless telephone network. The collected reference waveforms are used by a fingerprint analyzer to distinguish telephone calls made by the authorized wireless telephone from telephone calls made by an unauthorized wireless telephone. The system maintains a pool of specially designated unassigned telephone numbers and selects one telephone number from the pool at random which is provided to a valid subscriber of an authorized wireless telephone. The randomly selected telephone number is to be called by the valid subscriber using the authorized cellular telephone for the purpose of collecting reference waveforms by the system. A radio frequency (RF) receiver of the system monitors and receives transmission signals from a plurality of wireless telephones. Each transmission signal contains a destination telephone number and an identification of its wireless telephone such as MIN/ESN identifiers. The system selects for purposes of collecting reference waveforms the transmission signal whose destination and wireless telephone identification respectively correspond to the randomly selected destination and the identification of the authorized wireless telephone. This ensures that that particular transmission signal belongs to the authorized wireless telephone of the valid subscriber rather than an unauthorized wireless telephone belonging to a pirate since the pirate has no way of knowing the randomly selected telephone number provided to the valid subscriber. The processor then extracts the reference waveform that represents a transmission characteristic of the authorized wireless telephone and stores the extracted reference waveform in memory for use by the fingerprint analyzer.

Claims

1. A method of collecting a reference waveform from an authorized wireless telephone in a wireless telephone system including a fingerprint analyzer that identifies an unauthenticated wireless telephone as authorized or fraudulent based on a fingerprint analysis by comparing a transmission characteristic of the unauthenticated wireless telephone with a stored fingerprint of a corresponding authorized wireless telephone, the method comprising the steps of:

(a) selecting a first destination to be called by the authorized wireless telephone;

(b) associating the selected destination to be called by the authorized wireless telephone with a first identification of the authorized wireless telephone;

(c) receiving from a wireless telephone a transmission signal containing a transmitted destination and a transmitted identification of the wireless telephone transmitting the transmission signal;

(d) determining whether the transmitted destination and the transmitted identification of the transmitting wireless telephone respectively correspond to the selected first destination and the associated first identification of the authorized wireless telephone; and

(e) if the transmitted destination and the transmitted identification of the transmitting wireless telephone are determined to respectively correspond to the selected first destination and the associated first identification of the authorized wireless telephone, performing the following steps;

extracting from the transmission signal a reference waveform indicative of a transmission characteristic of the transmitting wireless telephone; and

storing the extracted reference waveform as a reference waveform of the authorized wireless telephone for subsequent use by the fingerprint analyzer.

2. The method according to claim 1, further comprising repeating steps (c) to (e) until a predetermined number of extracted reference waveforms are stored as reference waveforms of the authorized wireless telephone.

3. The method according to claim 1 wherein step (e) further comprises the step or connecting the authorized wireless telephone to an announcement module.

4. The method according to claim 3, further comprising the step of causing the announcement module to play a voice message indicating that a user of the transmitting wireless telephone is to call the selected first destination again whereby an additional reference waveform is collected.

5. The method according to claim 1, prior to step (c), further comprising the step of removing a previously stored fingerprint of the authorized wireless telephone.

6. The method according to claim 1, further comprising the step of building a fingerprint using the stored extracted reference waveform.

7. The method according to claim 1 wherein in step (a) the first destination to be called by the authorized wireless telephone is randomly selected from a plurality of predetermined unassigned destinations.

8. The method according to claim 1 wherein in step (a) the first destination to be called by the authorized wireless telephone is a pseudo-random destination telephone number.

9. The method according to claim 1 wherein step (e) further comprises repeating the following steps n times where n is greater than one:

polling the transmitting wireless telephone to automatically stimulate a transmission response signal containing a reference waveform indicative of a transmission characteristic of the transmitting wireless telephone;

receiving from the transmitting wireless telephone the transmission response signal responsive to the poll;

extracting the reference waveform from the received transmission response signal; and

storing the extracted reference waveform from the received transmission response signal for subsequent use by the fingerprint analyzer.

10. The method according to claim 9 wherein the step of polling comprises transmitting to the transmitting wireless telephone one of a page, registration, audit and maintenance message to stimulate the transmission response signal.

11. The method according to claim 9 wherein the step of polling comprises transmitting a page message to the transmitting wireless telephone, and further including, after the step of polling, the step of transmitting a hang-up message to the transmitting wireless telephone to prevent the transmitting wireless telephone from ringing.

12. A method of collecting a reference waveform from an authorized wireless telephone to be subsequently used by a fingerprint analyzer to distinguish telephone calls made by the authorized wireless telephone from telephone calls made by an unauthorized wireless telephone, the method comprising the steps of:

(a) selecting a destination to be called by the authorized wireless telephone;

(b) associating the selected destination to be called by the authorized wireless telephone with an identification of the authorized wireless telephone;

(c) monitoring transmission signals from a plurality of wireless telephones, each transmission signal containing a destination and an identification of the wireless telephone transmitting the transmission signal;

(d) identifying a transmission signal among the monitored transmission signals whose destination and identification contained therein respectively correspond to the selected destination and the associated identification of the authorized wireless telephone;

(e) obtaining a reference waveform from the wireless telephone transmitting the identified transmission signal; and

(f) storing the obtained reference waveform as a reference waveform of the authorized wireless telephone for subsequent use by the fingerprint analyzer.

13. The method according to claim 12 wherein step (e) comprises extracting from the identified transmission signal a reference waveform indicative of a transmission characteristic of the wireless telephone transmitting the identified transmission signal.

14. The method according to claim 12, further comprising repeating steps (e) to (f) until a predetermined number of reference waveforms are stored as reference waveforms of the authorized wireless telephone.

15. The method according to claim 12 wherein in step (a) the destination to be called by the authorized wireless telephone is randomly selected from a plurality of unassigned destinations.

16. The method according to claim 12 wherein in step (a) the destination to be called by the authorized wireless telephone is a pseudo-random destination telephone number.

17. The method according to claim 12 wherein steps (e) to (f) comprise repeating the following steps n times where n is greater than one:

polling the wireless telephone transmitting the identified transmission signal to automatically stimulate a transmission response signal containing a reference waveform indicative of a transmission characteristic of the wireless telephone transmitting the identified transmission signal;

receiving from the wireless telephone transmitting the identified transmission signal the transmission response signal responsive to the poll;

extracting the reference waveform from the received transmission response signal; and

storing the extracted reference waveform as a reference waveform of the authorized wireless telephone for subsequent use by the fingerprint analyzer.

19. The method according to claim 17 wherein step (f) comprises extracting from the identified transmission signal a reference waveform indicative of a transmission characteristic of the wireless telephone transmitting the identified transmission signal.

20. The method according to claim 17, further comprising repeating steps (f) to (g) until a predetermined number of obtained reference waveforms are stored as reference waveforms of the authorized wireless telephone.

21. The method according to claim 17, after step (e), further comprising the step of connecting the wireless telephone transmitting the identified transmission signal to an announcement module.

22. The method according to claim 21, further comprising the step of causing the announcement module to play a voice message indicating that the valid user of the authorized wireless telephone is to call the selected destination again whereby an additional reference waveform is obtained.

18. A method of collecting a reference waveform from an authorized wireless telephone to be subsequently used by a fingerprint analyzer to distinguish telephone calls made by the authorized wireless telephone from telephone calls made by an unauthorized wireless telephone, the method comprising the steps of:

(a) selecting a destination to be called by a valid user using the authorized wireless telephone;

(b) associating the selected destination with an identification of the authorized wireless telephone;

(c) providing the selected destination to the valid user of the authorized wireless telephone;

(d) monitoring transmission signals from a plurality of wireless telephones, each transmission signal containing a destination and an identification of a wireless telephone;

(e) identifying among the monitored transmission signals a transmission signal whose destination and identification contained therein respectively correspond to the selected destination and the associated identification of the authorized wireless telephone;

(f) obtaining, from the wireless telephone transmitting the identified transmission signal, a reference waveform indicative of a transmission characteristic of the wireless telephone transmitting the identified transmission signal; and

(g) storing the obtained reference waveform as a reference waveform of the authorized wireless telephone for subsequent use by the fingerprint analyzer.

23. The method according to claim 18, prior to step (d), further comprising the step of removing a previously stored fingerprint of the authorized wireless telephone.

24. The method according to claim 18, further comprising the step of building a fingerprint using the stored reference waveform.

25. The method according to claim 18 wherein in step (a) the destination to be called by the authorized wireless telephone is randomly selected from a plurality of unassigned destinations.

26. The method according to claim 18 wherein in step (a) the destination to be called by the authorized wireless telephone is a pseudo-random destination telephone number.

27. The method according to claim 18 wherein step (f) comprises:

polling the wireless telephone transmitting the identified transmission signal to automatically stimulate a transmission response signal containing a reference waveform indicative of a transmission characteristic of the wireless telephone transmitting the identified transmission signal;

receiving from the wireless telephone transmitting the identified transmission signal the transmission response signal responsive to the poll; and

extracting the reference waveform from the received transmission response signal.

28. The method according to claim 27 wherein the step of polling comprises transmitting to the wireless telephone transmitting the identified transmission signal one of a page, registration, audit and maintenance message.

29. The method according to claim 27 wherein the step of polling comprises transmitting a page message to the wireless telephone transmitting the identified transmission signal, and further including, after the step of polling, the step of transmitting a hang-up message to the wireless telephone transmitting the identified transmission signal to prevent the wireless telephone transmitting the identified transmission signal from ringing.

30. A system for collecting a reference waveform from an authorized wireless telephone to be subsequently used by a fingerprint analyzer to distinguish telephone calls made by the authorized wireless telephone from telephone calls made by an unauthorized wireless telephone, wherein a user of the authorized wireless telephone is provided with a destination to be called using the authorized wireless telephone, the system comprising:

a radio frequency (RF) receiver operable to receive transmission signals from a plurality of wireless telephones, each transmission signal containing a destination and an identification of a wireless telephone;

a processor connected to the RF receiver, the processor operable to monitor transmission signals received by the RF receiver and select a transmission signal among the monitored transmission signals whose destination and identification contained therein respectively correspond to the provided destination and the identification of the authorized wireless telephone, and obtain a reference waveform from the wireless telephone transmitting the selected transmission signal, the obtained reference waveform being indicative of a transmission characteristic of the wireless telephone transmitting the selected transmission signal; and

a memory connected to the processor and operable to store the obtained reference waveform as a reference waveform of the authorized wireless telephone for subsequent use by the fingerprint analyzer.

31. The system according to claim 30 wherein the processor randomly selects the provided destination among a plurality of unassigned destinations.

32. The system according to claim 30 wherein the processor pseudo-randomly generates the destination.

33. The system according to claim 32 wherein the processor uses the identification of the authorized wireless telephone to generate the pseudo-random destination.

34. The system according to claim 30, further comprising an announcement module connected to the processor and operable to play a voice message.

35. The system according to claim 34 wherein the voice message indicates that the user of the wireless telephone transmitting the selected transmission signal is to call the provided destination again whereby an additional reference waveform is collected.

36. The system according to claim 34, further comprising a switching system connected to the announcement module and programmed to route the call from the wireless telephone transmitting the selected transmission signal to the announcement module.

37. The system according to claim 36, further comprising:

a voice channel transceiver operable to transmit the voice message to the wireless telephone transmitting the selected transmission signal; and

a cell controller connected to the voice channel transceiver and the switching system, and operable to connect the voice channel transceiver to the switching system.

38. The system according to claim 37 wherein the authorized wireless telephone is a cellular telephone and the RF receiver is a control channel receiver.

39. A system for collecting a reference waveform from an authorized wireless telephone to be subsequently used to distinguish telephone calls made by the authorized wireless telephone from telephone calls made by an unauthorized wireless telephone, wherein a user of the authorized wireless telephone is provided with a destination to be called using the authorized wireless telephone, the system comprising:

a radio frequency (RF) receiver operable to receive transmission signals from a plurality of wireless telephones, each transmission signal containing a destination and an identification of a wireless telephone;

a processor connected to the RF receiver, the processor operable to select a wireless telephone transmitting a transmission signal whose destination and identification contained therein respectively correspond to the provided destination and the identification of the authorized wireless telephone, and obtain a reference waveform from the selected wireless telephone, the obtained reference waveform being indicative of a transmission characteristic of the selected wireless telephone; and

a memory connected to the processor and operable to store the obtained reference waveform.

40. The system according to claim 39 wherein the processor randomly selects the provided destination among a plurality of unassigned destinations.

41. The system according to claim 39 wherein the processor pseudo-randomly generates the destination.

42. The system according to claim 39, further comprising an announcement module connected to the processor and operable to play a voice message.

43. The system according to claim 42 wherein the voice message indicates that the user of the selected wireless telephone is to call the destination again whereby an additional reference waveform is collected.

44. The system according to claim 42, further comprising a switching system connected to the announcement module and programmed to route the call from the selected wireless telephone to the announcement module.

45. The system according to claim 44, further comprising:

a voice channel transceiver operable to transmit the voice message to the selected wireless telephone; and

a cell controller connected to the voice channel transceiver and the switching system, and operable to connect the voice channel transceiver to the switching system.

46. The system according to claim 39, further comprising a fingerprint analyzer connected to the RF receiver and operable to identify an unauthenticated wireless telephone as authorized or fraudulent based on a fingerprint analysis by comparing a transmission characteristic of the unauthenticated wireless telephone with a stored fingerprint of a corresponding authorized wireless telephone.

47. The system according to claim 39 located at a cell site for use with other similar collection systems located at other cell sites wherein the processor comprises:

a first processor connected to the RF receiver and located at the cell site;

a data link; and

a second processor connected to the first processor through the data link, the second processor being connected to other processors of the other similar collection systems located at the other cell sites through the data link.

48. The system according to claim 47 wherein the second processor is load shared with the first processor located at the cell site and the other processors located at the other cell sites.