TECHNIQUES FOR PROVIDING BROADCAST SERVICES ON SPOT BEAM SATELLITES

• US 20080233952A1
• Filed: 03/20/2008
• Published: 09/25/2008
• Est. Priority Date: 03/21/2007
• Status: Active Grant

• Current Assignee: ViaSat Incorporated
• Original Assignee: ViaSat Incorporated
• Inventors: Miller, Mark J.
• Granted Patent: US 8,660,481 B2
• Time in Patent Office: Days
• US Class Current: 455/427
• CPC Class Codes: H04B 7/18515 Transmission equipment in satellites or space-based relays
• CPC Class Codes: H04B 7/18523 Satellite systems for providing broadcast service to terrestrial stations, i.e. broadcast satellite service arrangements specially adapted for satellite broadcast receiving H04H40/90; picture transmission via satellite H04N1/00103; television transmission via satellite H04N7/20
• CPC Class Codes: H04B 7/2041 Spot beam multiple access

Abstract

Techniques for providing broadcast services on spot beam satellite are provided. These techniques enable the mission of a spot beam satellite system to be changed from providing spot beam transmission to broadcast transmissions, and vice versa, without requiring that the satellite be reconfigured. Broadcast data may be encoded and transmitted concurrently on a plurality of spot beams. According to some embodiments, the broadcast data may be encoded using a space-time code and/or forward error corrected (FEC) encoded to enable a receiver to correct errors in the signal received from the spot beam satellite.

Claims

1. A satellite system for providing broadcast services:

a spot beam satellite operable in a first mode to provide broadcast data to a broadcast coverage area via a plurality of spot beams and operable in a second mode to provide spot beam transmissions via the plurality of spot beams to a plurality of spot beam coverage areas, wherein when the spot beam satellite is operating in the second mode, each spot beam may transmit different data to receivers within a spot beam coverage area associated with the spot beam.

2. The system of claim 1, wherein when the spot beam satellite is operating in the first mode, each of the plurality of spot beams transmits the broadcast data on the same frequency at the same time to the plurality of spot beam coverage areas comprising the broadcast coverage area.

3. The system of claim 2, wherein at least a portion of the spot beam coverage areas comprising the broadcast coverage area comprise contiguous geographical areas.

4. The system of claim 2, wherein the broadcast data is space-time encoded.

5. The system of claim 4, wherein the broadcast data is space-time encoded using an orthogonal space-time code.

6. The system of claim 4, wherein the broadcast data is modulated such that the data transmitted on the plurality of spot beams is symbol synchronized

7. The system of claim 6, wherein the broadcast data is forward error correction (FEC) encoded to enable receivers within the broadcast coverage area to correct errors in the broadcast data received by the receivers.

8. The system of claim 7, wherein the spot beam satellite receives the broadcast data from a broadcast signal source via a plurality of uplink signals, wherein the plurality of uplink signals comprises a separate uplink signal for each of the plurality of spot beams.

9. The system of claim 8, wherein the broadcast data is modulated, space-time encoded, and FEC encoded at the broadcast signal source.

10. The system of claim 5, wherein the spot beam satellite is one of a constellation of low earth orbit (LEO) satellites comprising the satellite system, wherein one or more spot beams from one or more the constellation of LEO satellites provide broadcast data to the broadcast coverage area, and wherein the one or more spot beams from one or more the constellation of LEO satellites that provide broadcast data vary with time.

11. The system of claim 10, wherein space-time encoding used to generate encode the broadcast data is dynamically updated to produce an encoded output signals corresponding to one or more spot beams from one or more the constellation of LEO satellites currently providing broadcast data to a broadcast coverage area.

12. The system of claim 1, wherein the spot beam satellite comprises a Ka-band spot beam satellite configured to transmit at a first frequency using a first subset of the plurality of spot beams and to transmit at a second frequency using a second subset of the plurality of spot beams, and

wherein the broadcast data is encoded using an orthogonal space-time code, and

wherein the broadcast data is separately encoded for the first subset of the plurality of spot beams and for the second subset of the plurality of spot beams.

13. A broadcast signal source for providing broadcast data to a spot beam satellite broadcasting system, the broadcast signal source comprising:

a transmitter configured to transmit a plurality of uplink signals to a spot beam satellite, wherein each of the uplink signals corresponds to a spot beam of the spot beam satellite; and

a data encoder module for encoding the broadcast data such that the spot beam satellite may simultaneously broadcast the encoded data on at least a portion of the plurality of spot beams using the same frequency.

14. The broadcast signal source of claim 13, wherein the data encoder encodes the broadcast data using space-time encoding, wherein the space-time encoding produces a plurality of encoded output signals, each encoded output signal corresponding to one of the plurality of spot beams of the spot beam satellite.

15. The broadcast signal source of claim 14, wherein the broadcast data is space-time encoded using an orthogonal space-time code.

16. The broadcast signal source of claim 14, wherein the data encoder modulates a plurality of encoded output signals on separate carrier signals.

17. The broadcast signal source of claim 14, wherein the data encoder forward error correction (FEC) encodes the broadcast data prior to encoding the broadcast data using space-time encoding.

18. The broadcast signal source of claim 13, wherein the spot beam satellite broadcasting system comprises a constellation of low earth orbit (LEO) satellites, wherein one or more spot beams from one or more the constellation of LEO satellites provide broadcast data to a broadcast coverage area, wherein the one or more spot beams from one or more the constellation of LEO satellites that provide broadcast data vary with time, and wherein the space-time encoding dynamically updates to produce an encoded output signals corresponding to one or more spot beams from one or more the constellation of LEO satellites currently providing broadcast data to a broadcast coverage area.

19. The broadcast signal source of claim 13, wherein the spot beam satellite comprises a Ka-band spot beam satellite configured to transmit at a first frequency using a first subset of the plurality of spot beams and to transmit at a second frequency using a second subset of the plurality of spot beams, and

wherein the data encoder module is configured to encode the broadcast data using an orthogonal space-time code, and

wherein the broadcast data is separately encoded for the first subset of the plurality of spot beams and for the second subset of the plurality of spot beams.

20. A method for broadcasting data using a spot-beam satellite system comprising:

encoding the broadcast data to provide a plurality of encoded data signals, wherein each of the plurality of encoded data signals corresponds to one of a plurality of spot beams of a spot-beam satellite, and wherein the data is encoded such that the spot beam satellite may simultaneously broadcast the encoded data on at least a portion of the plurality of spot beams using the same frequency on each of the spot beams;

broadcasting the broadcast data using the plurality of spot-beams of the spot beam satellite.

21. The method of claim 20, wherein encoding the broadcast data further comprises:

encoding the broadcast data with a space-time code (STC) to produce a plurality of space-time encoded signals corresponding to each of the plurality of beams of the spot beam satellite.

22. The method of claim 21, wherein the STC is an orthogonal space-time code.

23. The method of claim 21, wherein encoding the broadcast data further comprises:

modulating the plurality of space-time encoded signals such that the data transmitted on the plurality of spot beams is symbol synchronized.

24. The method of claim 23, further comprising:

forward error correction (FEC) encoding the broadcast data prior to space-time encoding the broadcast data.

25. The method of claim 20, wherein at least a portion of the spot beam coverage areas comprising the broadcast coverage area comprise contiguous geographical areas.

26. The method of claim 20, wherein the spot beam satellite broadcasting system comprises a constellation of low earth orbit (LEO) satellites, wherein one or more spot beams from one or more the constellation of LEO satellites provide broadcast data to a broadcast coverage area, wherein the one or more spot beams from one or more the constellation of LEO satellites that provide broadcast data vary with time, and wherein encoding the broadcast data to provide a plurality of encoded data signals further comprises:

encoding output signals corresponding to one or more spot beams from one or more the constellation of LEO satellites currently providing broadcast data to a broadcast coverage area.

27. The method of claim 21, wherein the spot beam satellite comprises a Ka-band spot beam satellite configured to transmit at a first frequency using a first subset of the plurality of spot beams and to transmit at a second frequency using a second subset of the plurality of spot beams, and

wherein encoding the broadcast data with the STC to produce a plurality of space-time encoded signal corresponding to each of the plurality of beams of the spot beam satellite further comprises:

separately encoding with the STC the broadcast data for the first subset of the plurality of spot beams and for the second subset of the plurality of spot beams.