SATELLITE COMMUNICATION SYSTEM AND METHOD WITH ASYMMETRIC FEEDER AND SERVICE FREQUENCY BANDS

• US 20080146145A1
• Filed: 12/12/2007
• Published: 06/19/2008
• Est. Priority Date: 12/14/2006
• Status: Active Grant

• Current Assignee: ViaSat Incorporated
• Original Assignee: ViaSat Incorporated
• Inventors: Pateros, Charles N., Dankberg, Mark D.
• Granted Patent: US 7,869,759 B2
• Time in Patent Office: Days
• US Class Current: 455/12.1
• CPC Class Codes: H04B 7/18515 Transmission equipment in satellites or space-based relays
• CPC Class Codes: H04B 7/1858 Arrangements for data transmission on the physical system, i.e. for data bit transmission between network components

Abstract

System and method for communicating data in a multibeam satellite system having feeder beams associated with a plurality of gateways and a plurality of service beams associated with a plurality of user subscriber terminals utilizing frequency re-use by service beams between a satellite and a plurality of subscriber terminals, wherein the service beams are transmitted to and from the satellite by re-using at least one common frequency channel of the service beam, such that the beam allocation is asymmetric among available frequency channels. The result is a potential for reduction of transponder resources.

Claims

1. In a satellite communication system, a method for communicating between a central source and a plurality of user terminals via feeder frequency bands and service frequency bands, said method comprising:

generating uplink feeder beams and downlink feeder beams, said uplink feeder beams and downlink feeder beams being associated with a plurality of gateways via a satellite, said uplink feeder beams and said downlink feeder beams being characterized by a selection of feeder signals of first frequencies and first polarization slots, and each said feeder signal corresponding with a different color in a first selection of colors in a color map, each color being characterized by a unique frequency band and unique signal polarization; and

generating a plurality of uplink service beams and downlink service beams, said uplink service beams and downlink service beams being associated with a plurality of user subscriber terminals via the satellite, said service beams being characterized by a selection of second frequencies and second polarization slots, and each said feeder signal corresponding with a different color in a second selection of colors in said color map, said second color selection being less in number than said first color selection, such that the feeder frequency bands and the service frequency bands are asymmetric among available frequency channels.

2. The method according to claim 1, further including the step of:

reusing frequencies in the feeder beams between said satellite and said plurality of gateways, wherein the gateway beams transmit to and from the satellite re-using at least one common frequency channel of the feeder beams, such that allocation of frequency and polarization slots of the feeder beams is asymmetric.

3. In a satellite communication system having a method for communicating between a central source and a plurality of user terminals via feeder frequency bands and service frequency bands, the improvement in the method comprising:

modifying a four-color reuse pattern for assigning spot coverage areas so that the ratio of a select group of the four colors in the pattern is not equal, thereby allowing for asymmetric service frequency usage on service downlinks and thereby requiring fewer than conventional numbers of types of frequency translators.

4. The method according to claim 3, wherein uplink service links employ three identical frequency bandwidths, each with two orthogonal polarizations, and downlink feeder links employ two frequency bandwidths, each with two orthogonal polarizations, and wherein the frequency bandwidths between the uplink feeder links and the downlink feeder links are reused asymmetrically to reduce the required number of separate and unique elements on a satellite.

5. The method according to claim 3, wherein at least one uplink feeder beam comprises six carriers, wherein the beam comprises three frequency channels, each of the three frequency channels being operatively separated by right hand circular polarization (RHCP) and left hand circular polarization (LHCP), to form six unique combinations of frequency and polarization (colors), and wherein each of the six carriers is transmitted using only one of the six unique combinations of frequency and polarization.

6. The method according to claim 3, wherein the downlink service beams include one of four carriers, wherein the carriers are chosen from two frequency bands, each of the two frequency bands being capable of being separated by right hand circular polarization (RHCP) and left hand circular polarization (LHCP), to form four unique combinations of frequency and polarization (colors), and wherein each of the four carriers is transmitted using one of the four unique combinations of frequency and polarization to spot beam cells according to the four color pattern.

7. A method for communicating data in a multibeam satellite system with frequency re-use comprising:

providing feeder beams and service beams including uplink feeder beams to a relay satellite from a gateway ground station and downlink service beams between the relay satellite and a plurality of subscriber terminals, each service beam being associated with a different at least partially non-overlapping service beam coverage area, to form a plurality of service beam coverage areas;

wherein the plurality of the downlink service beams is transmitted to the subscriber terminals by re-using at least one common downlink frequency channel, the allocation of downlink service beam channels being asymmetrically allocated among available downlink frequencies.

8. A method for communicating data in a multibeam satellite system utilizing frequency re-use comprising:

providing feeder beams and service beams including uplink service beams and downlink feeder beams between a satellite and a plurality of gateways, each feeder beam being associated with a different at least partially non-overlapping service beam coverage area, to form a plurality of feeder beam coverage areas,

wherein the plurality of the uplink service beams is transmitted to the satellite by re-using at least one common uplink frequency channel, and an associated downlink feeder beam combines the information of the plurality of uplink service beams received by the satellite, the satellite re-using for reception said at least one common uplink frequency channel.

9. A system for communicating data in a multibeam satellite system utilizing frequency re-use comprising:

a gateway ground station providing feeder beams and service beams including uplink feeder beams to a relay satellite and downlink service beams between the relay satellite and a plurality of subscriber terminals, each service beam being associated with a different at least partially non-overlapping service beam coverage area, to form a plurality of service beam coverage areas;

wherein the plurality of the downlink service beams is transmitted to the subscriber terminals by re-using at least one common downlink frequency channel, the allocation of downlink service beam channels being asymmetrically allocated among available downlink frequencies.

10. The system according to claim 9 wherein said gateway ground station further provides downlink feeder beams between the satellite and the plurality of gateways, to form a plurality of feeder beam coverage areas,

wherein the plurality of the uplink service beams is transmitted to the satellite by re-using at least one common uplink frequency channel, and an associated downlink feeder beam combines the information of the plurality of uplink service beams received by the satellite, the satellite re-using for reception said at least one common uplink frequency channel.

11. A satellite communication system for communicating between a central source and a plurality of user terminals via feeder frequency bands and service frequency bands, said system comprising:

a gateway ground station configured for generating uplink feeder beams and downlink feeder beams via a satellite, said uplink feeder beams and said downlink feeder beams being characterized by a selection of feeder signals of first frequencies and first polarization slots, and each said feeder signal corresponding with a different color in a first selection of colors in a color map, each color being characterized by a unique frequency band and unique signal polarization; and

a plurality of user subscriber terminals configured for generating a plurality of uplink service beams and downlink service beams, said service beams being characterized by a selection of second frequencies and second polarization slots, and each said feeder signal corresponding with a different color in a second selection of colors in said color map, said second color selection being less in number than said first color selection;

such that the feeder frequency bands and the service frequency bands are asymmetric among available frequency channels.

12. The system according to claim 11, further comprising:

a controller configured for reusing frequencies in the feeder beams between said satellite and said plurality of gateways, wherein the gateway beams transmit to and from the satellite re-using at least one common frequency channel of the feeder beams, such that allocation of frequency and polarization slots of the feeder beams is asymmetric.

13. A satellite communication system employing a method for communicating between a central source and a plurality of user terminals via feeder frequency bands and service frequency bands, the system comprising:

a controller operative to modify a four-color reuse pattern for assigning spot coverage areas so that the ratio of a select group of the four colors in the pattern is not equal, thereby allowing for asymmetric service frequency usage on service downlinks and thereby requiring fewer than conventional numbers of types of frequency translators.

14. The system according to claim 13, wherein uplink service links employ three identical frequency bandwidths, each with two orthogonal polarizations, and downlink feeder links employ two frequency bandwidths, each with two orthogonal polarizations, and wherein the frequency bandwidths between the uplink feeder links and the downlink feeder links are reused asymmetrically to reduce the required number of separate and unique elements on a satellite.

15. The system according to claim 13, wherein at least one uplink feeder beam comprises six carriers, wherein the beam comprises three frequency channels, each of the three frequency channels being operatively separated by right hand circular polarization (RHCP) and left hand circular polarization (LHCP), to form six unique combinations of frequency and polarization (colors), and wherein each of the six carriers is transmitted using only one of the six unique combinations of frequency and polarization.

16. The system according to claim 13, wherein the downlink service beams include one of four carriers, wherein the carriers are chosen from two frequency bands, each of the two frequency bands being capable of being separated by right hand circular polarization (RHCP) and left hand circular polarization (LHCP), to form four unique combinations of frequency and polarization (colors), and wherein each of the four carriers is transmitted using one of the four unique combinations of frequency and polarization to spot beam cells according to the four color pattern.