Directional routing of packets in a satellite network

• US 6,404,769 B1
• Filed: 05/18/1998
• Issued: 06/11/2002
• Est. Priority Date: 06/26/1996
• Status: Expired due to Term

• Current Assignee: CDC Propriete Intellectuelle
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Kapoor, Vijay
• Primary Examiner(s): LUTHER, WILLIAM A
• Application Number:
  US09/080,179
• Time in Patent Office: 1,485 Days
• Field of Search: 370/230, 370/404, 370/408, 370/411, 370/406, 370/316, 370/409, 370/401, 370/412, 370/397, 370/428, 370/429, 370/398, 370/399, 370/393, 370/392, 370/355, 370/356, 370/465, 370/473, 370/474, 370/475, 370/325, 370/422, 370/503, 370/509, 370/512, 370/517, 370/386, 370/471, 370/217, 370/244, 370/251, 370/252, 370/253, 370/254, 340/3.43, 340/3.42, 340/7.27, 455/12, 455/33, 455/32, 455/13, 342/350, 342/354, 342/355, 342/356, 379/221.01, 379/221.06, 379/229, 379/230
• US Class Current: 370/398
• CPC Class Codes: H04B 7/18584 Arrangements for data networking, i.e. for data packet routing, for congestion control data switching networks H04L12/00

Abstract

A method and apparatus encompasses a technique for routing an information packet through a satellite communications system 20 from a source satellite 38 to a destination satellite 40. A path through the system 20 is chosen for the packet and an identifier identifying the path is appended to the packet. In addition, an identifier identifying the destination satellite 40 is appended to the packet. Satellites in the system 20 then use the identifiers in the packet to route the packet to the destination satellite 40. If the chosen path is not available, an alternate path can be taken by the packet. In one embodiment of the present invention, a centralized controller 36 is provided for controlling the routing of packets throughout the entire system 20.

Claims

1. In a satellite communications system having a constellation of satellites orbiting about a primary body, wherein said satellites represent nodes in a communications network, a method for use in routing an information packet from a source node to a destination node in said communications network, said method comprising the steps of:

providing a satellite communications network having a plurality of nodes and a plurality of paths connecting said plurality of nodes, said plurality of paths including a first group of paths having a first orientation and a second group of paths having a second, different orientation, wherein said first group of paths intersects said second group of paths at multiple node points;

providing an information packet at a source node, in said satellite communications network, said information packet to be delivered to a destination node in said satellite communications network, wherein said source node is on a first path in said first group of paths and said destination node is on a second, different path in said first group of paths;

monitoring traffic levels on said second group of paths from a centralized location in the satellite communications system;

choosing a third path from said second group of paths to carry said information packet from said first path to said second path based on traffic levels determined in said monitoring step; and

delivering said information packet from said source node to said destination node via a route including said third path.

2. The method of claim 1, wherein:

said first group of paths is substantially orthogonal to said second group of paths.

3. The method of claim 1, wherein:

said first group of paths includes a group of substantially polar orbital planes.

4. The method of claim 3, wherein:

said second group of paths includes a group of crossconnects substantially orthogonal to said group of substantially polar orbital planes, wherein each of said crossconnects comprises a band about said primary body that is stationary with respect to said primary body.

5. The method of claim 1, wherein:

said step of monitoring includes determining traffic information for said second group of paths in a centralized controller based on information flow routes previously assigned by said centralized controller.

6. The method of claim 1, wherein:

said step of delivering includes appending an identifier to said information packet identifying said third path.

7. The method of claim 1, wherein:

said step of delivering includes appending an identifier to said information packet identifying said destination node.

8. In a satellite communications system having a constellation of satellites arranged in a plurality of substantially polar orbital planes about the earth, wherein each of said plurality of substantially polar orbital planes are substantially fixed in relation to one another and each includes multiple satellites, a method for routing an information packet between a source satellite in a first orbital plane and a destination satellite in a second, different orbital plane, said method comprising the steps of:

defining a plurality of communications channels between predetermined orbital planes in said constellation;

choosing a first communications channel out of said plurality of communications channels to carry said information packet from said first orbital plane to said second orbital plane, based on information traffic levels in at least some of said plurality of communications channels, said first communications channel being chosen as a channel existing within a band having a traffic level that is relatively uncongested, said traffic level being determined based on monitoring said information traffic levels, wherein the band encircles the earth in an approximately east/west direction and is substantially stationary with respect to the earth; and

delivering said information packet from said source satellite to said destination satellite via a route including said first communications channel;

wherein said step of defining a plurality of communication channels includes defining a plurality of communication channels for use in delivering information packets in an approximately east/west direction.

9. The method of claim 8, wherein:

said step of defining a plurality of communication channels includes defining a plurality of communication channels that are approximately parallel to lines of constant latitude.

10. The method of claim 8, wherein:

said information traffic levels are monitored from a centralized location within said satellite communications system.

11. The method of claim 8, wherein:

said step of defining a plurality of communications channels includes defining a plurality of bands, each band encircling the earth in a substantially east/west direction and including a plurality of satellites for effecting communication between said predetermined orbital planes.

12. The method of claim 8, wherein:

said information traffic levels are monitored by tracking previously assigned information flow routes.

13. In a satellite communications system having a constellation of satellites arranged in a plurality of substantially polar orbital planes about the earth, wherein each of said plurality of orbital planes are substantially fixed in relation to one another and each includes multiple satellites, a method for routing an information packet between a source satellite in a first orbital plane and a destination satellite in a second, different orbital plane, said method comprising the steps of:

defining a plurality of communications channels connecting orbital planes in said constellation;

choosing a first communications channel out of said plurality of communications channels for use in delivering said information packet from said first orbital plane to said second orbital plane;

appending a unique orbital plane identifier corresponding to said second orbital plane, a unique satellite identifier corresponding to said destination satellite, and a unique channel identifier corresponding to said first communications channel to said information packet to create a modified information packet; and

using said identifiers in said modified information packet to deliver said modified information packet from said source satellite to said destination satellite, wherein said step of using includes using said unique channel identifier at an intermediate satellite between said source satellite and said destination satellite to determine whether said intermediate satellite is part of said first communications channel.

14. The method of claim 13, wherein:

said step of defining a plurality of communications channels includes defining a plurality of channels that are approximately parallel to lines of constant latitude.

15. The method of claim 13, wherein:

said step of choosing includes choosing based on information traffic levels in said constellation.

16. The method of claim 13, wherein said step of using includes:

determining whether said source satellite is part of said first communications channel;

when said source satellite is part of said first communications channel, transferring said information packet from said source satellite to another satellite within said first communications channel; and

when said source satellite is not part of said first communications channel, transferring said information packet to another satellite within said first orbital plane.

17. The method of claim 16, wherein:

said step of transferring said information packet to another satellite within said first orbital plane includes transferring said information packet in a direction of shortest path length to said first communications channel.

18. The method of claim 13, wherein said step of using includes the steps of:

receiving said modified information packet at a first satellite; and

determining whether said first satellite is said destination satellite using said unique orbital plane identifier and said unique satellite identifier from said modified information packet.

19. The method of Claim,13, wherein said step of using includes the steps of:

receiving said modified information packet at a first satellite;

determining whether said first satellite is within said second orbital plane using said unique orbital plane identifier from said modified information packet; and

when said first satellite is determined to be within said second orbital plane;

determining whether said first satellite is said destination satellite using said unique satellite identifier from said modified information packet; and

when said first satellite is determined not to be said destination satellite, transferring said modified information packet to another satellite in said second orbital plane.

20. The method of claim 19, wherein said step of using includes the step of:

when said first satellite is determined not to be within said second orbital plane;

determining whether said first satellite is part of said first communications channel using said unique channel identifier from said modified information packet;

when said first satellite is determined to be part of said first communications channel, transferring said modified information packet to another satellite within said first communications channel; and

when said first satellite is determined not to be part of said first communications channel, transferring said modified information packet to another satellite within an orbital plane of said intermediate satellite.

21. In a centralized controller for use in a satellite communications system having a constellation of satellites orbiting about a primary body and a plurality of predetermined paths between satellites in said constellation, a method for use in controlling information packet flow between satellites in said constellation, said method comprising the steps of:

monitoring present information traffic levels on said plurality of predetermined paths based on information packet flow routes previously assigned by said centralized controller;

monitoring said constellation of satellites to determine whether a connection has been requested between a first satellite and a second satellite within said constellation; and

when a connection has been requested, assigning a route to said connection, from said first satellite to said second satellite, based on said present information traffic levels determined in said step of monitoring present information traffic levels to reduce congestion on said predetermined paths in said satellite communications system.

22. The method of claim 21, wherein:

said step of assigning further comprises the step of assigning a route based on a desired quality of service.

23. A satellite communications system, comprising:

a fixed geometry constellation of satellites orbiting a primary body, wherein satellites in said constellation represent nodes in a communications network;

a plurality of predetermined communications paths between satellites in said constellation; and

a centralized controller that monitors information traffic levels on at least two of said plurality of predetermined paths and determines information packet flow routes through said constellation of satellites based on said information traffic levels to reduce traffic congestion in said satellite communications system.

24. The system of claim 23, wherein:

said centralized controller is spatially separated from said constellation of satellites.

25. The system of claim 23, wherein:

said centralized controller is ground based.

26. The system of claim 23, further comprising:

a plurality of signalling channels for facilitating communication between said centralized controller and said satellites in said constellation of satellites.

27. The system of claim 23, wherein:

said centralized controller monitors said information traffic levels using previously assigned information packet flow routes.

28. The system of claim 23, wherein:

said fixed geometry constellation of satellites includes a plurality of polar orbital planes, each polar orbital plane including multiple satellites.

29. The system of claim 23, wherein:

said centralized controller includes memory means for storing present information traffic levels.