Satellite mobile telephone cell departure prediction

• US 20050250558A1
• Filed: 07/14/2005
• Published: 11/10/2005
• 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 7,474,873 B2
• Time in Patent Office: Days
• US Class Current: 455/574
• 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 operating a satellite mobile telephone having a sleep mode to conserve power and an awake mode to receive satellite signals in a satellite mobile telephone system in which a plurality of cells move across the surface of the Earth as a satellite orbits, comprising:

receiving data related to the movement of a cell relative to the Earth'"'"'s surface;

operating in the sleep mode and entering the awake mode upon termination of the sleep mode; and

upon entering the awake mode, using the received data to determine at the mobile telephone a prediction for the time when the mobile telephone will leave the cell.

2. The method of claim 1, further comprising initiating a cell selection operation at the predicted time when the mobile telephone will leave the cell.

3. The method of claim 1, further comprising selecting at the mobile telephone a control channel to be monitored on the basis of the prediction.

4. The method of claim 1, further comprising determining at the mobile telephone the correctness of the prediction and performing a network registration process for the mobile telephone in dependence on the determined correctness.

5. The method of claim 4 wherein receiving the data related to the movement of the cell relative to the Earth'"'"'s surface is performed upon entering the awake mode.

6. The method of claim 4 wherein receiving the data related to the movement of the cell relative to the Earth'"'"'s surface comprises receiving the data from the satellite.

7. The method of claim 6 wherein the mobile telephone receives the data from the satellite via a control channel.

8. The method of claim 1 wherein the data related to the movement of the cell comprises data related to a position of a central portion of the cell and a translational vector indicating a movement of the central portion of the cell.

9. The method of claim 1 wherein the data related to the movement of the cell is calculated for a predetermined period of time.

10. The method of claim 1 wherein the data related to the movement of the cell is calculated for a plurality of predetermined periods of time covering a time range that exceeds the prediction for the time when the mobile telephone will leave the cell.

11. The method of claim 1 wherein mobile telephone is communicating with a selected satellite access node (SAN) via the satellite, the method further comprising receiving location data indicating a location of the mobile telephone from the SAN via the satellite.

12. The method of claim 11 wherein the mobile telephone uses the location data in combination with the received data related to the movement of the cell to determine at the mobile telephone the prediction for the time when the mobile telephone will leave the cell.