System and Method for Intercepting Cellular Satellite Communication

• US 20080293355A1
• Filed: 04/20/2006
• Published: 11/27/2008
• Est. Priority Date: 04/20/2005
• Status: Active Grant

• Current Assignee: ELTA Systems Limited (Government of Israel)
• Original Assignee: ELTA Systems Limited (Government of Israel)
• Inventors: Giloh, Benjamin
• Granted Patent: US 8,406,685 B2
• Time in Patent Office: Days
• US Class Current: 455/3.02
• CPC Class Codes: H04B 7/18567 Arrangements for providing additional services to the basic mobile satellite telephony service
• CPC Class Codes: H04M 2207/18 wireless networks
• CPC Class Codes: H04M 3/2281 Call monitoring, e.g. for law enforcement purposes; Call tracing; Detection or prevention of malicious calls

Abstract

The present invention provides a method for intercepting and monitoring of cellular satellite communication wherein communication between at least one mobile device (MES) and the satellite is through a first band link that includes plurality of first-band spot beams each accommodating at least one basic channel unit that includes a control channel and corresponding traffic channels, and communication between the satellite and main station is through wideband second-band link accommodating plurality of second band spot beams each accommodating at least one basic channel unit that includes a control channel and corresponding traffic channels, the method comprising detecting map between a control channel of the downlink first band link and corresponding control channel of downlink second band link by identifying identical unique spot beam number (SB Mask) data in the respective control channels.

Claims

1. A method for intercepting and monitoring of cellular satellite communication wherein communication between at least one mobile device (MES) and the satellite is through a first band link that includes plurality of first-band spot beams each accommodating at least one basic channel unit that includes a control channel and corresponding traffic channels, and communication between the satellite and main station is through wideband second-band link accommodating plurality of second band spot beams each accommodating at least one basic channel unit that includes a control channel and corresponding traffic channels, the method comprising detecting map between a control channel of the downlink first band link and corresponding control channel of downlink second band link by identifying identical unique spot beam number (SB_Mask) data in the respective control channels.

2. The method according to claim 1, wherein (a) comprising:

i) finding Broadcast control Channel (BCCH) constituting said control channel of the downlink first band, and identifying SB_Mask signals derived there from;

ii) finding at least one Random Access Control Channel (RACH) in downlink second band link according to a predetermined criterion, and identifying respective SB_Mask data derived therefrom;

iii) identifying identical SB-Mask signals in said BCCH and RACH channels;

the RACH, from among said at least one RACH, with the identified SB-Mask being the control channel of the downlink second band.

3. The method according to claim 2, wherein said finding BCCH includes identifying BCCH and measuring BCCH rate of calls and wherein finding RACH includes measuring substantially simultaneously energy of plurality of signals in respective channels of said downlink second band and wherein said criterion includes analyzing the measured energy to identify RACH signals at a rate that matches said BCCR rate of calls, and wherein said identifying SB_Mask signal includes analyzing the SB MASK data in said found BCCH and RACH signals for identifying the identical SB_Mask data.

4. The method according to claim 3, wherein said measuring BCCH rate of calls includes measuring rate of Access Grant signals (AGCR) per time unit.

5. The method according to claim 1, further comprising extracting data from the RACH signal of the control channel.

6. The method according to claim 5, wherein said extracted data includes GPS data indicative of the geographical location of the MES.

7. The method according to claim 1, further comprising finding an Access Grant (AGCH) signal in the control channel of said downlink first band and identifying corresponding RACH signal in the control channel in said downlink second band;

said identifying including determining identical request reference signal in said AGCR and RACR signals.

8. The method according to claim 1, further comprising detecting a map between traffic channels in said downlink second link and downlink first link that correspond to said control channels.

9. The method according to claim 8, wherein said detecting includes switching to a traffic channel in said first band according to data extracted from an Access Grant (AGCH) signal found in said downlink first band, and identifying corresponding SABM signal in a channel in the downlink second band link according to a predetermined criterion;

the latter channel being the traffic channel in said downlink second band.

10. The method according to claim 9, wherein said identifying includes measuring substantially simultaneously energy bursts in channels of said downlink second band link and wherein said criterion includes identifying at least one channel in which the respective energy burst is at first timing substantially identical to a second timing of said (AGCH) signal, and for said at least one channels identifying a channel with a sequence of SABM signals;

the latter channel constituting said traffic channel in the downlink second band link.

11. The method according to claim 8, further comprising processing communication in said traffic channels.

12. The method according to claim 11, wherein said processing includes applying decryption and demodulation to said communication giving rise to plain media data.

13. The method according to claim 1, wherein said first band being L band and said second band being C band.

14. The method according to claim 1, wherein said satellite being the Aces.

16. The method according to claim 8, further comprising detecting a map between traffic channels in said downlink second link and downlink first link that correspond to said control channels.

17. The method according to claim 16, further comprising processing communication in said traffic channels.

18. The method according to claim 17, wherein said processing includes applying decryption and demodulation to said communication giving rise to plain media data.

15. A method for intercepting and monitoring of cellular satellite communication wherein communication between at least one mobile device (MES) and the satellite is through a first band link that includes plurality of first-band channels, and communication between the satellite and main station is through wideband second-band link that include plurality of second-band channels, the method comprising detecting a map between a channel of the downlink first band link and corresponding channel of downlink second band link by identifying identical unique spot beam number (SB_Mask) data in the respective control channels.

19. The method according to claim 15, wherein said first band being L band and said second band being C band.

20. The method according to claim 15, wherein said satellite being the Aces.

21. A method for intercepting and monitoring of cellular satellite communication wherein communication between at least one mobile device (MES) and the satellite is through first band link that includes plurality of first band spot beams each accommodating at least one basic channel unit that includes a control channel and corresponding traffic channels, and communication between the satellite and main station is through wideband second-band link accommodating plurality of first band spot beams each accommodating at least one basic channel unit that includes a control channel and corresponding traffic channels, the method comprising detecting a map between traffic channels in said downlink second link and downlink first link that correspond to said control channels, including finding an access grant (AGCH) signal at a first timing in said downlink first band and identifying a corresponding traffic channel in downlink:

second band link by identifying an SABM signal at a second timing that corresponds to said first timing.

22. The method according to claim 21, wherein said detecting includes switching to a traffic channel in said first band according to data extracted from an Access Grant (AGCH) signal found in said downlink first band, and identifying corresponding SABM signal in a channel in the downlink second band link according to a predetermined criterion;

the latter channel being the traffic channel in said downlink second band.

23. The method according to claim 22, wherein said identifying includes measuring substantially simultaneously energy bursts in channels of said downlink second band link and wherein said criterion includes identifying at least one channel in which the respective energy burst is at first timing substantially identical to a second timing of said AGCH, and for said at least one channels identifying a channel with a sequence of SABM signals;

the latter channel constituting said traffic channel in the downlink C band link.

24. The method according to claim 21, further comprising, processing the communication in said corresponding traffic channels.

25. The method according to claim 24, wherein said processing includes applying decryption and demodulation to said communication giving rise to plain media data.

26. The method according to claim 21, wherein said first band being L band and said second band being C band.

27. The method according to claim 21, said satellite being the Aces.

28. A method for intercepting and monitoring of cellular satellite communication wherein communication between at least one mobile device (MES) and the satellite is through first band link that includes plurality of first band channels, and communication between the satellite and main station is through wideband second-band link that include plurality of second-band channels, and wherein said satellite maps dynamically a channel in the first band to a channel in the second band, the method comprising:

(a) detecting a map between a channel of the downlink first band link and corresponding channel of downlink second band link, irrespective of said dynamic mapping.

29. The method according to claim 28, wherein said detecting includes identifying identical unique spot beam number (SB_Mask) data in the respective control channels.

30. The method according to claim 28, further comprising detecting a map between traffic channels in said downlink second link and downlink first link that correspond to said control channels.

31. The method according to claim 28, wherein said first-band being L band and said second band being C band.

32. A method for intercepting and monitoring of satellite communication wherein communication between at least one mobile device (MES) and the satellite is through a first band link that includes plurality of first-band channels, and communication between the satellite and main station is through wideband second-band link that include plurality of second-band channels, the method comprising

(i) detecting a map between a control channel of the downlink first band link and corresponding control channel of said downlink second band link;

(ii) detecting a map between a traffic channel associated with the control channel of said downlink first band link and a traffic channel associated with the control channel of said second-band link.

33. The method according to claim 32, wherein said detecting (i) includes

(1) finding Broadcast control Channel (BCCR) of said control channel of the downlink first band, and

(2) finding a corresponding Random Access Control Channel (RACH) in said downlink second band link.

34. The method according to claim 32, wherein said detecting (ii) includes:

(1) finding an Access Grant signal (AGCH) in said control channel of the downlink first band which AGCH corresponding to said RACH, and based on the AGCH data, identifying a traffic channel associated with the control channel of said downlink first band link.

35. The method according to claim 33, further comprising extracting a spot beam number (SB_Mask) data from said BCCH and extracting a spot beam number (SB_Mask) data from said RACH, and in the case of identity between said extracted SB-Masks, determining that said BCCH corresponds to said RACR.

36. The method according to claim 34, further comprising extracting a request reference signal from said RACR and extracting a request reference signal from said AGCR, and in the case of identity between said extracted request reference signal, determining that said AGCR corresponds to said RACR.

37. The method according to claim 32, further comprising processing communication in said traffic channels.

38. The method according to claim 37, wherein said processing includes applying decryption and demodulation to said communication giving rise to plain media data.

39. The method according to claim 32, wherein said first-band being L band and said second band being C band.

40. The method according to claim 32, wherein the satellite allocating additional at least one control and associated traffic channels to a spot, the method further comprising

(i) detecting a map between additional control channel of the downlink first band link and corresponding additional control channel of said downlink second band link;

(ii) detecting a map between additional traffic channel associated with the additional control channel of said downlink first band link and additional traffic channel associated with the additional control channel of said second-band link

41. A system for intercepting and monitoring of cellular satellite communication wherein communication between at least one mobile device (MES) and the satellite is through a first band link that includes plurality of first-band spot beams each accommodating at least one basic channel unit that includes a control channel and corresponding traffic channels, and communication between the satellite and main station is through wideband second-band link accommodating plurality of second band spot beams each accommodating at least one basic channel unit that includes a control channel and corresponding traffic channels, the system comprising apparatus being configured to detect map between a control channel of the downlink first band link and corresponding control channel of downlink second band link by identifying identical unique spot beam number (SB_Mask) data in the respective control channels.

42. A system for intercepting and monitoring of cellular satellite communication wherein communication between at least one mobile device (MES) and the satellite is through a first band link that includes plurality of first-band channels, and communication between the satellite and main station is through wideband second-band link that include plurality of second-band channels, the system comprising apparatus being configured to detect a map between a channel of the downlink first band link and corresponding channel of downlink second band link by identifying identical unique spot beam number (SB_Mask) data in the respective control channels.

43. A system for intercepting and monitoring of cellular satellite communication wherein communication between at least one mobile device (MES) and the satellite is through first band link that includes plurality of first-band spot beams each accommodating at least one basic channel unit that includes a control channel and corresponding traffic channels, and communication between the satellite and main station is through wideband second-band link accommodating plurality of first band spot beams each accommodating at least one basic channel unit that includes a control channel and corresponding traffic channels, the system comprising apparatus being configured to detect a map between traffic channels in said downlink second link and downlink first link that correspond to said control channels, including finding an access grant (AGCH) signal at a first timing in said downlink first band and identifying a corresponding traffic channel in downlink second band link by identifying an SABM signal at a second timing that corresponds to said first timing.

44. A system for intercepting and monitoring of cellular satellite communication wherein communication between at least one mobile device (MES) and the satellite is through first band link that includes plurality of first-band Channels, and communication between the satellite and main station is through wideband second-band link that include plurality of second-band channels, and wherein said satellite maps dynamically a channel in the first band to a channel in the second band, the system comprising apparatus being configured to detect a map between a channel of the downlink first band link and corresponding channel of downlink second band link, irrespective of said dynamic mapping.

45. A system for intercepting and monitoring of satellite communication wherein communication between at least one mobile device (MES) and the satellite is through a first band link that includes plurality of first-band channels, and communication between the satellite and main station is through wideband second-band link that include plurality of second-band channels, the system comprising apparatus being configured to detect a map between a control channel of the downlink first band link and corresponding control channel of said downlink second band link;

the apparatus being further configured to detect a map between a traffic channel associated with the control channel of said downlink first band link and a traffic channel associated with the control channel of said second-band link.

46-60. -60. (canceled)