Downstream broad beam diversity with interference cancellation

• US 7,904,020 B2
• Filed: 08/22/2007
• Issued: 03/08/2011
• Est. Priority Date: 08/22/2006
• Status: Active Grant

• Current Assignee: ViaSat Incorporated
• Original Assignee: ViaSat Incorporated
• Inventors: Pateros, Charles N., Dankberg, Mark D.
• Primary Examiner(s): Gesesse; Tilahun
• Application Number:
  US11/843,096
• Publication Number:
  US 20080143589A1
• Time in Patent Office: 1,294 Days
• Field of Search: 455/12.1, 455/13.1, 455/427, 455/428, 455/429, 455/430, 455/12.11, 455/421
• US Class Current: 455/12.1
• CPC Class Codes: H04B 7/10 Polarisation diversity; Directional diversity
• 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 7/18517 Transmission equipment in earth stations
• CPC Class Codes: H04B 7/2041 Spot beam multiple access
• CPC Class Codes: H04L 27/2647 Arrangements specific to the receiver only equalisation H04L27/01
• CPC Class Codes: H04L 5/0016 Time-frequency-code
• CPC Class Codes: H04L 5/0026 Division using four or more dimensions
• CPC Class Codes: H04L 5/12 the signals being represented by different phase modulations of a single carrier

Abstract

Downstream satellite communication systems and methods are disclosed according to embodiments of the invention. According to embodiments of the invention, a composite signal may be received by a subscriber terminal that includes at least a first signal that is transmitted from a first user through a first satellite, a second signal that is transmitted from the first user through a second satellite, and a third signal that is transmitted from a second user through the second satellite. The first signal and the second signal are transmitted to the first and second satellites as the same signal from a gateway, transmitter or subscriber terminal. The third signal is isolated from the composite signal and the subtracted from the composite signal.

Claims

1. A subscriber terminal for communicating with a gateway through more than one satellite relay comprising:

an antenna configured to receive a composite signal from more than one satellite relay, wherein the composite signal includes a first signal that is transmitted from a first user through a first satellite, a second signal that is transmitted from the first user through a second satellite, and a third signal that is transmitted from a second user through the second satellite, wherein the first signal and the second signal are transmitted to the first and second satellites as the same signal;

an isolator module configured to;

isolate each of the first signal and the second signal from the composite signal; and

combine the first signal and the second signal to generate a received signal having a higher apparent signal strength than that of the first signal alone phase shift at least one of the first or the second signal so that the first signal and the second signal are in phase with respect to each other; and

add the first signal and the second signal.

2. The satellite communication system according to claim 1, wherein the isolator module includes a RAKE receiver.

3. The satellite communication system according to claim 1, wherein the isolator module includes an iterative combiner.

4. The satellite communication system according to claim 1, wherein the isolator module is configured to combine the first signal and the second signal to generate the received signal by:

synchronizing the first signal and the second signal; and

adding the first signal and the second signal.

5. The satellite communication system according to claim 1, wherein the isolator module is further configured to:

subtract the third signal from the composite signal.

6. A satellite communication system comprising:

a gateway including one or more antennas;

a plurality of satellites, including at least a first and a second satellite; and

a subscriber terminal in communication with the gateway through the plurality of satellites, wherein the subscriber terminal includes;

an antenna configured to receive a composite signal from the plurality of satellites, wherein the composite signal includes a first signal that is transmitted from the gateway through the first satellite, a second signal that is transmitted from the gateway through the second satellite, and a third signal that is transmitted from a first user through the second satellite, wherein the first signal and the second signal are the same signal when transmitted from the gateway;

an isolator module configured to;

isolate each of the first signal and the second signal from the composite signal; and

combine the first signal and the second signal to generate a received signal having a higher apparent signal strength than that of the first signal alone phase shift at least one of the first or the second signal so that the first signal and the second signal are in phase with respect to each other; and

add the first signal and the second signal.

7. The satellite communication system according to claim 6, wherein the first and second satellites orbit in different orbital slots.

8. The satellite communication system according to claim 6, wherein the first and second satellites orbit in adjacent orbital slots.

9. The satellite communication system according to claim 6, wherein the plurality of satellites comprises three satellites and the gateway comprises three antennas.

10. The satellite communication system according to claim 6, wherein the plurality of satellites comprises three satellites and the gateway comprises one antenna.

11. The satellite communication system according to claim 6, wherein the subscriber terminal antenna comprises a wide beam width antenna.

12. The satellite communication system according to claim 6, wherein the subscriber terminal antenna comprises a 6°

beam width.

13. The satellite communication system according to claim 6, wherein the subscriber terminal antenna comprises a 4°

beam width.

14. The satellite communication system according to claim 6, wherein:

the plurality of satellites comprises at least a third satellite; and

the subscriber terminals further include an antenna further configured to receive a fourth signal that is transmitted from the gateway through the third satellite, and a fifth signal that is transmitted from a second user through the third satellite, wherein the first signal and the fourth signal are the same signal when transmitted from the gateway, the isolator module configured to isolate the fourth signal from the composite signal, and combine the fourth signal with the first signal and the second signal to generate the received signal.

15. The satellite communication system according to claim 6, wherein the isolator module includes a RAKE receiver.

16. The satellite communication system according to claim 6, wherein the isolator module includes an iterative combiner.

17. A satellite communication method comprising:

receiving a composite signal at a subscriber terminal from a plurality of satellites;

wherein the composite signal includes a first signal that is transmitted from a first user through a first satellite, a second signal that is transmitted from the first user through a second satellite, and a third signal that is transmitted from a second user through the second satellite, wherein the first signal and the second signal are transmitted to the first and second satellites as the same signal;

isolating each of the first signal and the second signal from the composite signal; and

combining the first signal and the second signal to generate a received signal having a higher apparent signal strength than that of the first signal alone phase shifting at least one of the first or the second signal so that the first signal and the second signal are in phase with respect to each other; and

add the first signal and the second signal.

18. The method according to claim 17, wherein the composite signal includes a fourth signal that is transmitted from the first user through a third satellite and a fifth signal that is transmitted from a third user through the third satellite.

19. The method according to claim 18, further comprising isolating the fourth signal from the composite signal and combining the fourth signal with the first signal and the second signal to generate the received signal.

20. A satellite communication method comprising:

receiving a composite signal at a subscriber terminal from at least two satellites;

wherein the composite signal includes a first primary signal that is transmitted from a first user through a first satellite, a first secondary signal that is transmitted from a second user through the first satellite, a second primary signal that is transmitted from a third user through a second satellite, and a second secondary signal that is transmitted from the second user through the second satellite, wherein the first secondary signal and the second secondary signal are transmitted to the first and second satellites as the same signal;

isolating the first secondary signal from the composite signal;

isolating the second secondary signal from the composite signal; and

combining the first secondary signal and the second secondary signal to generate a received signal having a higher apparent signal strength than that of either the first secondary signal or the second secondary signal phase shifting at least one of the first or the second signal so that the first signal and the second signal are in phase with respect to each other; and

add the first signal and the second signal.

21. The satellite communication method according to claim 20, wherein the second user does not lease access to either or both of the first satellite or the second satellite.