Satellite mobile telephone cell departure prediction

• US 20040224632A1
• Filed: 05/26/2004
• Published: 11/11/2004
• Est. Priority Date: 07/16/1997
• Status: Active Grant

• Current Assignee: DBSD Services Ltd. (Echostar Corporation)
• Original Assignee: ICO Services, Ltd. (Echostar Corporation)
• Inventors: Hutchinson, Benjamin H.
• Granted Patent: US 7,260,391 B2
• Time in Patent Office: Days
• US Class Current: 455/12.1
• CPC Class Codes: H04B 7/18541 for handover of resources
• CPC Class Codes: H04B 7/18556 using a location database

Abstract

A mobile station (4) in a satellite mobile telephone system predicts when it will move into another cell on the basis of one set of broadcast information thereby reducing the overall processing burden. The mobile station (4) can predict with a useful degree of certainty which broadcast control channel (BCCH) frequencies it should listen on when it wakes up on the basis of a stored map of the relative positions of cells. The broadcast information includes information about the current cell'"'"'s (40) shape (V₁, V₂, V₃, V₄, V₅, V₆) and translational (T) and rotational (R) motion.

Claims

1. A method of operation of a satellite mobile telephone system in which a plurality of cells move across the surface of the Earth as a satellite orbits, the method comprising the steps of:

providing a mobile station with information related to the movement of a cell relative to the Earth'"'"'s surface; and

determining at the mobile station a prediction for the time when the mobile station will leave said cell on the basis of said received information.

2. A method according to claim 1, wherein said information is provided to the mobile station by broadcasting the information defining the geographical position of a cell from a satellite to that cell, and receiving said information for the cell at the mobile station.

3. A method according to claim 1, wherein said information includes information regarding the extent of the cell.

4. A method according to claim 1, wherein said information includes information regarding the traversing of the cell over the Earth'"'"'s surface.

7. A method according to claim 1, wherein said information comprises a set of translational vectors defining the traversing of the cell over the surface of the Earth during predetermined sub-periods of a period during which said information remains unchanged.

8. A method according to claim 7, wherein the mobile station predicts the sub-period during which it will leave the cell on the basis of the members of said set of translational vectors.

10. A method according to claim 8, wherein the mobile station predicts the time within said predicted sub-period when it will leave the cell.

11. A method according to claim 1, comprising the step selecting at the mobile station a control channel to be monitored on the basis of said prediction.

12. A method according to claim 1, comprising the step of determining at the mobile station the correctness of said prediction and performing a network registration process for the mobile station in dependence on said determined correctness.

5-6. -6. (Canceled)

9. (Canceled)

13. A satellite mobile telephone system comprising transmitting means for transmitting control data in a control channel, wherein the control data comprises geographical information defining the position of a cell associated with the control channel.

14. A system according to claim 13, wherein said information includes information regarding the extent of the cell.

15. A system according to claim 13, wherein said information includes information regarding the traversing of the cell over the Earth'"'"'s surface.

18. A system according to claim 13, wherein said information comprises a set of translational vectors defining the traversing of the cell over the surface of the Earth during predetermined sub-periods of a period during which said information remains unchanged.

16-17. -17. (Canceled)

19. (Canceled)

20. A mobile telephone for a satellite mobile telephone system, including memory means for storing control data including geographical information related to the movement of a cell across the Earth'"'"'s surface and processing means for processing said information to make a prediction of when the mobile station will depart the current cell.

21. A mobile telephone according to claim 20, including receiving means for receiving said geographical data, wherein said data relates to the cell in which the mobile station is located.

22. A mobile telephone according to claim 20, wherein the processing means is configured to predict a cell departure time for the mobile station on the basis of the members of a set of translational vectors comprised in said information and defining the traversing of the cell over the surface of the Earth.

23. A mobile telephone according to claim 22, wherein the processing means is configured to predict the cell departure time on the basis of a set of vectors comprised in said information and defining the rotation of the cell.

24. A mobile telephone according to claim 22, wherein the processing means is configured to predict a sub-period, during which the mobile telephone will leave the cell, of a period, during which the broadcast geographical information remains unchanged.

25. A mobile telephone according to claim 24, wherein the processing means is configured to predict the time within said predicted sub-period when the mobile station will leave the cell.

26. A mobile telephone according to claim 20, wherein the processing means is configured to determine the error between the predicted and actual cell departure times and, only if said error is greater than a predetermined value, cause the mobile telephone to transmit network registration request signals.