FLEXIBLE BEAMFORMING FOR SATELLITE COMMUNICATIONS

• US 20170288769A1
• Filed: 04/12/2017
• Published: 10/05/2017
• Est. Priority Date: 05/02/2010
• Status: Active Grant

• Current Assignee: ViaSat Incorporated
• Original Assignee: ViaSat Incorporated
• Inventors: Miller, Mark J., Pateros, Charles N., Mendelsohn, Aaron J., Runyon, Donald L.
• Granted Patent: US 10,511,379 B2
• Time in Patent Office: Days
• CPC Class Codes: H04B 7/0617 for beam forming
• 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 7/18543 for adaptation of transmission parameters, e.g. power control for detecting or preventing errors in the information received H04L1/00
• CPC Class Codes: H04B 7/2041 Spot beam multiple access
• CPC Class Codes: H04B 7/212 Time-division multiple access [TDMA]

Abstract

Systems and methods for supporting more flexible coverage areas and spatial capacity assignments using satellite communications systems are disclosed. A hub-spoke, bent-pipe satellite communications system includes: terminals; gateways; a controller for specifying data for controlling satellite operations in accordance with a frame definition including timeslots for a frame and defining an allocation of capacity between forward and return traffic. The satellite communications system may employ a satellite with a feed array assembly and may use on-board beamforming or ground-based beamforming. Beam hopping within timeslots of the frame may be used to provide coverage to different cells in different time periods. The flexible coverage areas may be provided using changes in satellite position, antenna patterns, or beam resource allocations.

Claims

1. A method for providing a communications service via a communications satellite, the method comprising:

obtaining a first transmit beamforming weight set that defines a plurality of first transmit spot beams based on a plurality of first antenna feed elements of the communications satellite;

applying, by a transmit beamforming network, the first transmit beamforming weight set to a plurality of first spot beam signals associated with the plurality of first transmit spot beams to obtain first transmit feed element signals;

transmitting the first transmit feed element signals via the plurality of first antenna feed elements to generate the plurality of first transmit spot beams;

obtaining a second transmit beamforming weight set that defines a plurality of second transmit spot beams based on the plurality of first antenna feed elements of the communications satellite;

updating, in response to a change in orbital position of the communications satellite, the transmit beamforming network to apply the second transmit beamforming weight set;

applying, by the transmit beamforming network, the second transmit beamforming weight set to a plurality of second spot beam signals to obtain second transmit feed element signals; and

transmitting the second transmit feed element signals via the plurality of first antenna feed elements to generate the plurality of second transmit spot beams.

2. The method of claim 1, further comprising:

obtaining a first receive beamforming weight set that defines a plurality of first receive spot beams based on a plurality of second antenna feed elements of the communications satellite;

receiving, via the plurality of second antenna feed elements, first receive feed element signals;

applying, at a receive beamforming network, the first receive beamforming weight set to the first receive feed element signals to obtain the plurality of first spot beam signals;

obtaining a second receive beamforming weight set that defines a plurality of second receive spot beams based on the plurality of second antenna feed elements;

updating, in response to the change in orbital position of the communications satellite, the receive beamforming network to apply the second receive beamforming weight set;

receiving, via the plurality of second antenna feed elements, second receive feed element signals; and

applying, at the receive beamforming network, the second receive beamforming weight set to the second receive feed element signals to obtain the plurality of second spot beam signals.

3. The method of claim 2, wherein the plurality of second antenna feed elements are the same as the plurality of first antenna feed elements.

4. The method of claim 3, wherein each of the plurality of first antenna feed elements is configured to operate with a first polarization for receiving the first receive feed element signals, and to operate with a second, orthogonal polarization for transmitting the first transmit feed element signals.

5. The method of claim 1, wherein the transmit beamforming network is coupled between a plurality of beam signal pathways of the communications satellite and the plurality of first antenna feed elements.

6. The method of claim 5, wherein each of the plurality of beam signal pathways is coupled with each of the plurality of first antenna feed elements via the transmit beamforming network.

7. The method of claim 5, wherein each of the plurality of beam signal pathways is coupled with a subset of the plurality of first antenna feed elements via the transmit beamforming network.

8. The method of claim 5, wherein each of the plurality of first spot beam signals is associated with one of the plurality of beam signal pathways.

9. The method of claim 1, further comprising:

storing the first transmit beamforming weight set at the communications satellite prior to deployment.

10. The method of claim 1, wherein the obtaining the second transmit beamforming weight set comprises receiving, at the communications satellite, the second transmit beamforming weight set from a network management entity.

11. The method of claim 1, wherein the obtaining the second transmit beamforming weight set comprises calculating, at the communications satellite, the second transmit beamforming weight set based at least in part on the change in orbital position of the communications satellite.

12. The method of claim 1, wherein the obtaining the second transmit beamforming weight set comprises selecting, at the communications satellite, the second transmit beamforming weight set from a plurality of beamforming weight sets stored at the communications satellite.

13. The method of claim 1, further comprising:

receiving, at the communications satellite, a multiplexed transmit signal comprising the first transmit feed element signals multiplexed with each other; and

demultiplexing the multiplexed transmit signal to separate each of the first transmit feed element signals.

14. The method of claim 13, wherein the transmit beamforming network is coupled between a plurality of beam signal pathways and an access node antenna transmitting the multiplexed transmit signal to the communications satellite.

15. The method of claim 13, wherein, in the multiplexed transmit signal, the first transmit feed element signals are time-division multiplexed, frequency-division multiplexed, or code-division multiplexed.

16. The method of claim 1, wherein:

each of the plurality of first transmit spot beams provides the communications service to one of a first plurality of cells; and

each of the plurality of second transmit spot beams provides the communications service to one of a second plurality of cells.

17. The method of claim 16, wherein at least one of the second spot beam signals is provided to a cell of the second plurality of cells via a corresponding second transmit spot beam with a same bandwidth as a corresponding first transmit spot beam, a same frequency as the corresponding first transmit spot beam, a same polarization as the corresponding first transmit spot beam, a same timing slot sequence as the corresponding first transmit spot beam, or a combination thereof.

18. The method of claim 16, wherein, for at least one of the second plurality of cells, the corresponding second transmit spot beam is provided with a same spot beam coverage area as a corresponding first transmit spot beam associated with a corresponding one of the first plurality of cells.

19. The method of claim 16, wherein the first plurality of cells is the same as the second plurality of cells.

20. The method of claim 1, wherein the plurality of second transmit spot beams provides the communications service over a same satellite coverage area as the plurality of first transmit spot beams.

21. The method of claim 16, wherein the first transmit beamforming weight set comprises a first plurality of transmit weight matrices, wherein each of the first plurality of transmit weight matrices defines a subset of the plurality of first transmit spot beams associated with a time slot of a first repeating pattern of time slots.

22. The method of claim 21, wherein the second transmit beamforming weight set comprises a second plurality of transmit weight matrices, wherein each of the second plurality of transmit weight matrices defines a subset of the plurality of second transmit spot beams associated with a time slot of a second repeating pattern of time slots.

23. The method of claim 21, wherein the first repeating pattern of time slots associates each of the time slots with a set of active cells, and wherein the second repeating pattern of time slots associates each of the time slots with the set of active cells.

24. The method of claim 1, further comprising:

performing respective frequency conversions on the plurality of first spot beam signals prior to transmitting the first transmit feed element signals.

25. The method of claim 24, further comprising:

adapting the respective frequency conversions in response to the change in orbital position of the communications satellite;

performing the adapted respective frequency conversions to the second spot beam signals prior to transmitting the second transmit feed element signals.

26. The method of claim 1, wherein the plurality of first transmit spot beams are based at least in part on an initial native antenna pattern, the method further comprising:

commanding a change to an adapted native antenna pattern based at least in part on the change in orbital position of the communications satellite.

27. A satellite communications system comprising a communications satellite for providing a communications service between a plurality of user terminals and a plurality of access node terminals, comprising:

means for applying a transmit beamforming weight set to a plurality of first beam signals to obtain first transmit feed signals, the transmit beamforming weight set defining a plurality of first transmit beams based on a plurality of first antenna feed elements of the communications satellite;

means for changing, in response to a change in orbital position of the communications satellite, the transmit beamforming weight set to obtain, from the means for applying, second transmit feed signals from second transmit beam signals; and

means for transmitting the first transmit feed signals and the second transmit feed signals from the communications satellite to generate the plurality of first transmit beams and a plurality of second transmit beams.

28. A satellite communications system comprising a communications satellite for providing a communications service between a plurality of user terminals and a plurality of access node terminals, comprising:

a plurality of first antenna feed elements on the communications satellite;

a plurality of spot beam signal pathways; and

a transmit beamforming network coupled between the plurality of spot beam signal pathways and the plurality of first antenna feed elements;

a beam weight processor configured to;

obtain a first transmit beamforming weight set that defines a plurality of first transmit spot beams based on the plurality of first antenna feed elements;

configure the transmit beamforming network to apply the first transmit beamforming weight set to a plurality of first spot beam signals associated with the plurality of first transmit spot beams to obtain first transmit feed element signals for transmission via the plurality of first antenna feed elements;

obtaining a second transmit beamforming weight set that defines a plurality of second transmit spot beams based on the plurality of first antenna feed elements of the communications satellite; and

configure, in response to a change in orbital position of the communications satellite, the transmit beamforming network to apply the second transmit beamforming weight set to second spot beam signals to obtain second transmit feed element signals for transmission via the plurality of first antenna feed elements.