Method and apparatus for providing wideband services using medium and low earth orbit satellites

• US 6,678,520 B1
• Filed: 07/01/1999
• Issued: 01/13/2004
• Est. Priority Date: 01/07/1999
• Status: Expired due to Term

• Current Assignee: Hughes Electronics Corporation (Rtx Corporation)
• Original Assignee: Hughes Electronics Corporation (Rtx Corporation)
• Inventors: Wang, Arthur W.
• Primary Examiner(s): VUONG, QUOCHIEN B
• Application Number:
  US09/346,444
• Time in Patent Office: 1,657 Days
• Field of Search: 455/12.1, 455/13.1, 455/436, 455/427-430, 455/63
• US Class Current: 455/428
• CPC Class Codes: H04B 7/18513 Transmission in a satellite or space-based system
• CPC Class Codes: H04B 7/18515 Transmission equipment in satellites or space-based relays
• CPC Class Codes: H04B 7/18541 for handover of resources
• CPC Class Codes: H04B 7/18578 Satellite systems for providing broadband data service to individual earth stations for selecting H04W; provisions for broadband connection, H04Q11/0478
• CPC Class Codes: H04B 7/1858 Arrangements for data transmission on the physical system, i.e. for data bit transmission between network components
• CPC Class Codes: H04B 7/19 Earth-synchronous stations
• CPC Class Codes: H04B 7/195 Non-synchronous stations

Abstract

A method and apparatus for mitigating communications interference between satellite communications systems in different orbits is disclosed. The method comprises the steps of evaluating a geometrical relationship between a second ground station and the satellites in the second satellite constellation, and directing communications between the second ground station and the second satellite according to the evaluated geometrical relationship. In one embodiment communications are handed over from a first satellite to another satellite when the first satellite is no longer at the highest elevation angle of visible satellites. In another embodiment, handover occurs when the first satellite drops below a minimum elevation angle.

Claims

1. A method of mitigating communication interference between a first satellite communicating with a first ground station and a second satellite communicating with a second ground station, wherein the second satellite is one of a plurality of satellites in a second satellite constellation having more than two satellites, comprising the steps of:

evaluating a geometrical relationship between the second ground station and the satellites in the second satellite constellation by determining an elevation angle for each of the satellites in the second satellite constellation, wherein the elevation angle for each satellite is measured from a local horizon of the second ground station to the satellite;

designating one of the plurality of satellites in the second satellite constellation disposed at a largest elevation angle as the handover satellite; and

directing communications between the second ground station and the second satellites in the second constellation according to the evaluated geometrical relationship by handing over communications between the second ground station and the second satellite to the handover satellite.

2. The method of claim 1, wherein the first satellite is in a geostationary orbit, and the second satellite is in a middle earth orbit.

3. The method of claim 1, wherein the first satellite is in a geostationary orbit, and the second satellite is in a low earth orbit.

4. The method of claim 1, wherein:

the step of evaluating the geometrical relationship between the second ground station and the satellites in the second satellite constellation comprises the step of determining an elevation angle for each of the satellites in the second satellite constellation, wherein the elevation angle for each satellite is measured from a local horizon of the second ground station to the satellite; and

the step of directing communications between the second ground station and the second constellation according to the evaluated geometrical relationship comprises the step of handing over communications between the second ground station and the second satellite to a handover satellite if the elevation angle for the second satellite is below a minimum elevation angle.

5. The method of claim 1, wherein the step of directing communications between the second ground station and the second constellation according to the evaluated geometrical relationship comprises the step of handing over communications between the second ground station and the second satellite to a handover satellite if the handover satellite is disposed at a higher elevation angle than the second satellite.

6. The method of claim 1, wherein the step of directing communications between the second ground station and the second constellation according to the evaluated geometrical relationship comprises the step of handing over communications between the second ground station and the second satellite to a handover satellite when the handover satellite is disposed at a higher elevation angle than the second satellite.

7. A method of mitigating communication interference between a first satellite communicating with a first ground station and a second satellite, wherein the second satellite is one of a plurality of satellites in a second satellite constellation and the first satellite is not a member of the second satellite constellation, comprising the steps of:

determining a separation angle for each of the satellites in the second satellite constellation, wherein the separation angle is an angle between the first satellite, a second ground station, and each respective satellite; and

handing over communications between the second ground station and the second satellite to a handover satellite, if the separation angle of the handover satellite is greater than the separation angle for the second satellite.

8. The method of claim 7, further comprising the step of:

designating one of the plurality of satellites associated with the largest separation angle as the handover satellite.

9. The method of claim 7, wherein communications between the second ground station and the second satellite are handed over to the handover satellite if the separation angle between the first satellite, a second ground station and the second satellite is less than ten degrees.

10. The method of claim 7, further comprising the step of:

designating one of the plurality of satellites in the second satellite constellation disposed at a largest elevation angle as the handover satellite.

11. The method of claim 7, wherein the first satellite is in a geostationary orbit and the second satellite is in a middle earth orbit.

12. The method of claim 7, wherein the first satellite is in a geostationary orbit and the second satellite is in a low earth orbit.

13. The method of claim 7, wherein the second satellite and the handover satellite each comprise a communication antenna for communicating with the second ground station, wherein the communication antenna has a sidelobe directivity of approximately 4 degrees.

14. The method of claim 7, wherein the second satellite constellation has more than two satellites, and the method further comprising the steps of:

evaluating a geometrical relationship between the second ground station and the satellites in the second constellation by determining an elevation angle for the satellites in the second satellite constellation, wherein the elevation angle for each satellite is measured from a local horizon of the second ground station to the satellite; and

designating one of the plurality of satellites in the second satellite constellation disposed at the largest elevation angle as the handover satellite.