Communication system with direct link to satellite

• US 5,995,041 A
• Filed: 12/30/1996
• Issued: 11/30/1999
• Est. Priority Date: 12/30/1996
• Status: Expired due to Term

• Current Assignee: Rakuten, Inc. (Rakuten Group, Inc.)
• Original Assignee: AT&T Corporation (AT&T, Inc.)
• Inventors: Bradley, James Frederick, Cooper, Paul W.
• Primary Examiner(s): OEN, WILLIAM L
• Application Number:
  US08/774,457
• Time in Patent Office: 1,065 Days
• Field of Search: 342/42, 342/43, 342/44, 342/50, 342/51, 342/52, 342/59, 342/133, 342/146, 342/357, 342/454, 342/457, 342/463, 342/702, 342/725, 342/790, 342/792, 342/878, 342/883, 455/12.1, 455/13.1, 455/13.2, 455/13.3, 455/56.1
• US Class Current: 342/357.75
• CPC Class Codes: H04B 7/18571 for satellites; for fixed or mobile stations

Abstract

A communication system includes satellites and satellite phones communicating through the satellites directly. The satellite phone forms a highly directed beam toward a satellite of the communications system and adaptively maintains a beam to track the satellite as the satellite phone and/or the satellite moves relative to each other. The satellite phone contains sensors which provide steering information for directing the satellite phone'"'"'s antenna beam. The communication system links a satellite phone with either another satellite phone and/or a ground based communication system connected to conventional telephone stations. The satellite phone also includes a database that contains the positional information of all potential communication satellites. The communication system coordinates satellite phone beams with a satellite network to facilitate high quality handoffs. Satellite phones can access several satellite networks based upon stored parameters or actively downloaded satellite information.

Claims

1. A communication system operating with a satellite network comprising:

a communication terminal coupled to the satellite network; and

a portable terminal that includes a directional antenna, wherein the portable terminal communicates with the communication terminal by directing an antenna beam of the directional antenna toward the satellite network based on information generated by the portable terminal.

2. The communication system of claim 1, wherein the portable terminal tracks the satellite based on a position of the satellite and portable terminal steering information including a position, a bearing and an attitude of the portable terminal.

3. The communication system of claim 2, wherein the portable terminal determines the portable terminal steering information based on Global Position System signals and detected portable terminal steering parameters.

4. The communication system of claim 2, wherein the portable terminal determines the satellite position by one of a database of the portable terminal and data transmitted by the satellite.

5. The communication system of claim 4, wherein the database includes orbital-path data for non-geostationary satellites, the portable terminal determining a position of the non-geostationary satellites based on the orbital-path data and a clock of the portable terminal.

6. The communication system of claim 2, wherein a communication between the portable terminal and the satellite is hand-off to a communication between the portable terminal and another satellite.

7. The communication system of claim 6, wherein the hand-off is performed by one of snapping the antenna beam and bridging the antenna beam.

8. The communication system of claim 7, wherein the snapping the antenna beam is performed after one of the satellite and the another satellite transmits a time-sync signal.

9. The communication system of claim 1, wherein the satellite network comprises at least one satellite.

10. The communication system of claim 8 wherein the at least one satellite includes at least one of a geostationary earth orbit satellite, a medium altitude earth orbit satellite, a low altitude earth orbit satellite, an intermediate circular orbit satellite and a geo-helio synchronous orbit satellite.

11. The communication system of claim 9, wherein the at least one satellite includes at least two satellites, the at least two satellites communicate with each other to form a first portion of a communication path between the portable terminal and the communication terminal.

12. The communication system of claim 11, wherein one of the at least one satellite communicates with a ground based communication network to form a second portion of the communication path between the portable terminal and the communication terminal.

13. The communication system of claim 12, wherein the ground based communication network is a telephone switching network coupled to a plurality of fixed terminals and a plurality of movable terminals.

14. The communication system of claim 13, wherein the ground based communication network is a data switching network connected to a plurality of data terminals.

15. The communication system of claim 11, wherein one of the at least one satellite communicates with the communication terminal directly to form a second portion of the communication path between the portable terminal and the communication terminal.

16. A method for operating a communication system, comprising:

coupling a portable terminal with a satellite network via an antenna beam of a directional antenna; and

establishing communications between the portable terminal and a communication terminal.

17. The method of claim 16, further comprising tracking the satellite based on a position of the satellite and portable terminal steering information including a position, a bearing and an attitude of the portable terminal.

18. The method of claim 17, further comprising handing-off from a communication between the portable terminal and the satellite to a communication between the portable terminal and another satellite.

19. The method of claim 18 wherein the handing-off step comprises one of snapping the antenna beam and bridging the antenna beam.

20. The method of claim 19, wherein the snapping step comprises transmitting a time-sync signal by one of the satellite and the another satellite.

21. The method of claim 17, further comprising determining the portable terminal steering information based on Global Position System signals and detected portable terminal steering parameters.

22. The method of claim 17, further comprising determining the satellite position by one of a database of the portable terminal and data transmitted by the satellite.

23. The method of claim 17, wherein the database includes orbital-path data for non-geostationary satellites, the portable terminal determining a position of the non-geostationary satellites based on the orbital-path data and a clock of the portable terminal.

24. The method of claim 16, wherein the satellite network comprises at least one satellite.

25. The method of claim 24, wherein the at least one satellite includes at least one of a geostationary earth orbit satellite, a medium altitude earth orbit satellite, a low altitude earth orbit satellite, an intermediate circular orbit satellite and a geo-helio synchronous orbit satellite.

26. The method of claim 24, further comprising forming a first portion of a communication path between the portable terminal and the communication terminal, wherein the at least one satellite includes at least two satellites, the at least two satellites communicate with each other to form the first portion of the communication path.

27. The method of claim 26 further comprising forming a second portion of the communication path between the portable terminal and the communication terminal by linking with a ground based communication network.

28. The method of claim 27, wherein the ground based communication network is a telephone switching network coupled to a plurality of fixed terminals and a plurality of movable terminals.

29. The method of claim 27, wherein the ground based communication network is a data switching network connected to a plurality of data terminals.

30. The method of claim 26, further comprising forming a second portion of the communication path between the portable terminal and the communication terminal by linking directly with the communication terminal.