Method and apparatus for autonomous user terminal assignment of time and frequency slots for call handoff

• US 6,064,883 A
• Filed: 07/09/1998
• Issued: 05/16/2000
• Est. Priority Date: 07/09/1998
• Status: Expired due to Term

• Current Assignee: Northrop Grumman Systems Corporation (Northrop Grumman Corporation)
• Original Assignee: TRW Inc. (Northrop Grumman Corporation)
• Inventors: Smith, Ronald P.
• Primary Examiner(s): LE, THANH C
• Application Number:
  US09/112,875
• Time in Patent Office: 677 Days
• Field of Search: 455/12.1, 455/13.1, 455/422, 455/427, 455/428, 455/429, 455/430, 455/517, 455/524, 370/315, 370/316, 370/319, 370/321, 370/323, 370/325, 370/341, 370/330, 370/331
• US Class Current: 455/428
• CPC Class Codes: H04B 7/18541 for handover of resources

Abstract

A method and apparatus for autonomous assignment of communications channels during call handoffs by a user terminal in a satellite-based telecommunications system. The method comprises the steps of transmitting a request for access from a user terminal to a control center via at least one satellite and selecting channel parameters and model assignment information for a first communications channel at the control center. The assignment information identifies predictable events which require the first user terminal to switch to a second communications channel. The channel parameters and model assignment information are transmitted from the control center to the first user terminal. A communications link is established over a first channel with the first user terminal. While the communications link with the first user terminal over the first channel is maintained, the user terminal autonomously switching its communications link to a second communications channel based on model assignment information identifying a predictable event preventing the first user terminal from continuing to use the first communications channel.

Claims

1. In a satellite based telecommunications system for transmitting communications information to and from a first user terminal, a method for controlling switching between communications channels comprising the steps of:

(a) transmitting a request for access from a user terminal to a control center via at least one satellite;

(b) selecting at said control center assignment information for a first communications channel, said assignment information identifying predictable events requiring said first user terminal to change between first and second communications channels;

(c) transmitting said assignment information to said first user terminal;

(d) after transmitting said assignment information to said first user terminal, establishing a communications link over said first communications channel with said first user terminal; and

(e) after establishing said communications link, said first user terminal autonomously switching said first communications channel to said second communications channel based on said assignment information indicating that a predictable event is about to occur preventing said first user terminal from continuing to use said first communications channel.

2. The method according to claim 1, wherein the steps of transmitting said assignment information to said first user, establishing a communications link over said first communications channel, and autonomously switching said first communications channel to said second communications channel are repeated until termination of transmission of said communications information.

3. The method according to claim 1, further comprising the steps of selecting channel parameters identifying a first channel over which said first user terminal communicates, and transmitting said channel parameters to said first user terminal via said at least one satellite before establishing said communications link over said first channel with said first user terminal.

4. The method according to claim 1, wherein said model assignment information comprises a satellite orbit submodel modeling an orbital pattern of at least one satellite to identify said predictable events.

5. The method according to claim 4, wherein said model assignment information further comprises a starting point identifying a current position of at least one satellite within said orbital pattern.

6. The method according to claim 1, wherein said predictable event identifies the point in time at which one cell coverage area passes beyond the first user terminal and a different cell coverage area covers the first user terminal due to satellites orbiting the Earth.

7. The method according to claim 1, further comprising the step of selecting, at the control center, new model assignment information for said second communications channel when an unpredictable event occurs, said new model assignment information identifying future predictable events requiring said first user terminal to change between said second communications channel and a third communications channel.

8. The method according to claim 7, further comprising the steps of selecting new channel parameters identifying said second communications channel, over which said first user terminal communicates when said unpredictable event occurs, and transmitting said new model assignment information to said first user terminal via said at least one satellite.

9. The method according to claim 7, wherein said unpredictable event represents one or more new user terminals requesting access to the system.

10. The method according to claim 7, wherein said unpredictable event represents said first user terminal moving out of one cell coverage area into a different cell coverage area due to movement of said first user terminal.

11. The method according to claim 7, wherein said unpredictable event represents a second user terminal located within the same cell coverage area as said first user terminal requesting an increase in the rate of data transmission.

12. A satellite based telecommunications system for transmitting communications information to and from a first user terminal, comprising:

a telecommunication satellite;

a user terminal for transmitting and receiving said communications information over a communications channel in a communications link with said satellite;

a control center for maintaining said communications link with said user terminal via said satellite, said user terminal establishing said communications link by requesting access to the system from said control center, said control center responding to said request for access by selecting and transmitting model assignment information for a first communications channel to said first user terminal, said model assignment information identifying future predictable events requiring switching by said first user terminal between said first communications channel and a second communications channel, said control center transmitting said model assignment information to said first user terminal, said user terminal, while maintaining said communications link over said first communications channel, autonomously switching said communications link to said second communications channel based on said model assignment information identifying a predictable event that prevents said first user terminal from continuing to use said first communications channel.

13. The system according to claim 12, wherein said control center responds to said request for access by selecting and transmitting channel parameters to said first user terminal, said channel parameters identifying said first communications channel over which said first user terminal communicates, and wherein said control center transmits said channel parameters to said first user terminal.

14. The system according to claim 12, further comprising a plurality of interlinked telecommunication satellites linked to said control center.

15. The system according to claim 12, wherein said control center selects new model assignment information for a second communications channel when an unpredictable event occurs, and transmits said new model assignment information to said first user terminal via said telecommunication satellite, said new model assignment information identifying future predictable events requiring said first user terminal to autonomously switch said second communications channel to a third communications channel based on said new model assignment information.

16. The system according to claim 15, wherein said control center selects new channel parameters identifying a second communications channel over which said first user terminal communicates, and transmits said new channel parameters to said first user terminal via said telecommunication satellite.

17. The system according to claim 15, wherein said unpredictable event represents one or more new user terminals requesting access to said system.

18. The system according to claim 15, wherein said unpredictable event represents said first user terminal moving out of one cell coverage area into a different cell coverage area due to movement of said first user terminal.

19. The system according to claim 15, wherein said unpredictable event represents a request for an increased data transmission rate by a second user terminal located within the cell coverage area covering said first user terminal.

20. The system according to claim 12, wherein said model assignment information comprises a satellite orbit submodel identifying a satellite orbit pattern of at least one satellite.

21. The system according to claim 20, wherein said model assignment information further comprises a starting point within said satellite orbit pattern.

22. The system according to claim 12, wherein said predictable event represents one cell coverage area moving beyond said first user terminal and a different cell coverage area moving to cover said first user terminal as satellites orbit the Earth.

23. A communications system for transmitting communications information to and from a first user terminal, comprising:

a user terminal for transmitting and receiving communications information over a communications channel;

a plurality of regional control centers for maintaining a communications link with said first user terminal, said first user terminal establishing said communications link by requesting access to the system, one of said regional control centers responding to said request for access by selecting and transmitting model assignment information for a first communications channel to said first user terminal, said model assignment information identifying future predictable events requiring switching by the first user terminal between said first communications channel and a second communications channel, said one regional control center transmitting said model assignment information to said first user terminal, said first user terminal, while maintaining said communications link over said first channel, autonomously switching said first communications channel to said second communications channel based on said model assignment information which identifies a predictable event that prevents said first user terminal from continuing to use said first communications channel.

24. The system according to claim 23, wherein said communication system is satellite based.

25. The system according to claim 24, further comprising a plurality of interlinked satellites linked to said regional control centers.

26. The system according to claim 25, wherein said model assignment information comprises a satellite orbit submodel identifying a satellite orbit pattern of at least one satellite.

27. The system according to claim 26, wherein said model assignment information further comprises a starting point.

28. The system according to claim 23, wherein said communication system is a land based telephone system.

29. The system according to claim 23, wherein said communication system is a fiber optics system.

30. The system according to claim 23, wherein said one regional control center responds to said request for access by selecting and transmitting channel parameters, said channel parameters identifying said first channel over which said first user terminal communicates, and said one regional control center transmits said channel parameters to said first user terminal.

31. The system according to claim 23, wherein said one regional control center selects new model assignment information for said second communications channel when an unpredictable event occurs, and transmits said new model assignment information to said first user terminal, said new model assignment information identifying future predictable events requiring said first user terminal to switch autonomously said second communications channel to a third communications channel based on said new model assignment information.

32. The system according to claim 31, wherein said control center selects new channel parameters identifying a second channel over which said first user terminal communicates, and transmits said new channel parameters to said first user terminal.

33. The system according to claim 31, wherein said unpredictable event is one or more new user terminals requesting access to said system.

34. The system according to claim 31, wherein said unpredictable event is said first user terminal moving out of one cell coverage area into a different cell coverage area due to movement of said first user terminal.

35. The method according to claim 31, wherein said unpredictable event is any user terminal located within the same cell coverage area as said first user terminal requesting an increase in the rate of data transmission.

36. The system according to claim 25, wherein said predictable event represents one cell coverage area moving beyond, and a different cell coverage area moving to cover, said first user terminal as satellites orbit the Earth.