Space-time division multiple-access laser communications system

• US 8,116,632 B2
• Filed: 11/26/2008
• Issued: 02/14/2012
• Est. Priority Date: 11/30/2007
• Status: Active Grant

• Current Assignee: Raytheon Company (Rtx Corporation)
• Original Assignee: Raytheon Company (Rtx Corporation)
• Inventors: Miniscalco, William J., O'Shea, Robert D., Smith, Irl W., Waldman, Howard L.
• Primary Examiner(s): Ben, Loha
• Application Number:
  US12/323,715
• Publication Number:
  US 20090214216A1
• Time in Patent Office: 1,175 Days
• Field of Search: 398/98, 398/103, 398/118, 398/121, 398/124, 398/125, 398/130, 398/135, 398/140, 370/203, 370/335, 370/337, 370/347, 370/352, 370/395.4, 375/146, 375/260, 375/343, 701/29, 701/33, 701/35, 455/137, 455/426, 455/426.1, 455/427, 455/428, 455/404.1, 455/456.1, 455/456.2, 455/553.1
• US Class Current: 398/118
• CPC Class Codes: H04B 10/112 Line-of-sight transmission over an extended range
• CPC Class Codes: H04B 7/18504 Aircraft used as relay or high altitude atmospheric platform
• CPC Class Codes: H04B 7/18506 Communications with or from aircraft, i.e. aeronautical mobile service
• CPC Class Codes: H04B 7/18508 with satellite system used as relay, i.e. aeronautical mobile satellite service
• CPC Class Codes: H04B 7/204 Multiple access

Abstract

A space-time division multiple-access (STDMA) laser communications (lasercom) system and related techniques. The STDMA system includes a plurality of remote nodes and an STDMA access node which uses precise electronic beam steering and beacons to provide access to each of a plurality of remote access nodes by means of both space and time-division multiple access.

Claims

1. A space-time division multiple-access (STDMA) laser communications system comprising:

a plurality of remote nodes; and

an STDMA node having an optical communications aperture and a plurality of optical pointing, acquisition and tracking (PAT) apertures, with each of the plurality of PAT apertures having a beacon beam in communication with one of said plurality of remotes nodes.

2. The system of claim 1 wherein to move a communications beam among said plurality of remote nodes, the optical communications aperture uses at least one of:

electronic beam steering;

or

mechanical beam steering.

3. The system of claim 1 wherein said STDMA node utilizes a space and time-division multiple access technique to communicate with each of said plurality of remote nodes.

4. The system of claim 1 wherein said STDMA node establishes a communication link between said STDMA node and each of said plurality of remote nodes.

5. The system of claim 4 wherein said communication links between said STDMA node and said plurality of remote nodes are one of:

unidirectional;

or

bidirectional.

6. The system of claim 5 wherein said communication links between said STDMA node and said plurality of remote nodes are different for each remote node.

7. The system of claim 4 wherein the communications links between said STDMA node and said plurality of remote terminals can utilize wavelength division multiplexing.

8. The system of claim 7 wherein the number of wavelengths multiplexed can vary among said plurality of remote nodes.

9. The system of claim 1 wherein said optical communications aperature is configured to operate only in transmit mode.

10. The system of claim 1 wherein said optical communications aperature is configured to operate only in receive mode.

11. The system of claim 1 wherein said optical communications aperature is configured to operate simultaneously in transmit and receive modes.

12. The system of claim 1 wherein said STDMA node is one of:

a stationary node or a mobile node.

13. The system of claim 1 wherein said plurality of remote nodes are one of:

a stationary node or a mobile node.

14. The system of claim 1 wherein the number of remote nodes served by a single STDMA node may be fixed or varying.

15. The system of claim 1 wherein said optical communications aperture is a first one of a plurality of optical communications apertures in said STDMA node.

16. The system of claim 1 wherein the number of PAT apertures on the STDMA node may be the same or different than the number of remote nodes.

17. The system of claim 1 wherein the number of tracking beacons transmitted from said STDMA node may be the same or different than the number of remote nodes.

18. The system of claim 1 wherein a dwell time of an STDMA node downlink (D/L) transmit beam and an uplink (U/L) receive direction may be the same for all remote nodes or different for some or all remote nodes.

19. The system of claim 1 wherein a revisit interval in a hopping sequence (latency) is the same for all remote nodes or different for some or all remote nodes.

20. A method for operating an optical communications system, the method comprising:

transmitting a plurality of beacon beams from an STDMA node to locate a corresponding plurality of remote nodes;

selecting one of said plurality of remote nodes; and

directing an STDMA node downlink (D/L) transmit beam to the selected remote node to establish a communications link between the STDMA node and the selected remote node.

21. The method of claim 20 wherein directing a downlink (D/L) transmit beam comprises electronic beam steering the downlink (D/L) transmit beam to the selected remote node.

22. The method of claim 21 wherein directing the downlink (D/L) transmit beam includes utilizing a space and time-division multiple access technique to communicate with each of said plurality of remote nodes.

23. The system of claim 22 wherein a dwell time of an STDMA node downlink (D/L) transmit beam is the same for all remote nodes.

24. The system of claim 22 wherein a dwell time of an STDMA node downlink (D/L) transmit beam is different for at least some of the plurality of remote nodes.

25. The method of claim 22 wherein a revisit interval in a hopping sequence is the same for all remote nodes.

26. The method of claim 22 wherein a revisit interval in a hopping sequence is different for at least some of the remote nodes.