SPACE-TIME DIVISION MULTIPLE-ACCESS LASER COMMUNICATIONS SYSTEM

• US 20090214216A1
• Filed: 11/26/2008
• Published: 08/27/2009
• Est. Priority Date: 11/30/2007
• Status: Active Grant

• Current Assignee: Raytheon Company (Rtx Corporation)
• Original Assignee: Raytheon Company (Rtx Corporation)
• Inventors: Waldman, Howard L., Smith, Irl W., Miniscalco, William J., O'Shea, Robert D.
• Granted Patent: US 8,116,632 B2
• Time in Patent Office: Days
• US Class Current: 398/89
• 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 access 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 the optical communications aperture uses at least one of:

electronic beam steering; and

mechanical beam steering to move a communications beam among said plurality of remote nodes.

3. The system of claim 1 wherein said STDMA access 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 access node establishes a communication link between said STDMA access node and each of said plurality of remote terminals.

5. The system of claim 1 wherein said communication link between said STDMA access node and said plurality of remote terminals is one of:

unidirectional or bidirectional.

6. The system of claim 5 wherein said communication link between said STDMA access node and said plurality of remote terminals is different for each remote terminal.

7. The system of claim 1 wherein said optical communications apertures are configured to operate only in transmit mode.

8. The system of claim 1 wherein said optical communications apertures are configured to operate only in receive mode.

9. The system of claim 1 wherein said optical communications apertures are configured to operate simultaneously in transmit and receive modes.

10. The system of claim 1 wherein said STDMA access node is one of stationary or mobile.

11. The system of claim 1 wherein said plurality of remote terminals are one of stationary or mobile.

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

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

14. The system of claim 1 wherein the number of PAT apertures on the multiple-access node may be the same or different than the number of remote terminals.

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

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

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

18. The system of claim 4 wherein the communications links between said STDMA access node and said plurality of remote terminals can utilize wavelength division multiplexing (WDMA).

19. The system of claim 18 wherein the number of wavelengths multiplexed can vary among said plurality of remote terminals.

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

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

selecting a one of said plurality of remote nodes; and

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

21. The method of claim 20 wherein directing a communications beam comprises electronic beam steering the communications beam to the selected remote node.

22. The method of claim 21 wherein directing a 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 access node downlink (D/L) transmit beam is the same for all remote terminals.

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

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

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