Ground network with access node clusters for end-to-end beamforming

• US 10,367,574 B1
• Filed: 11/08/2018
• Issued: 07/30/2019
• Est. Priority Date: 04/10/2015
• Status: Active Grant

• Current Assignee: ViaSat Incorporated
• Original Assignee: ViaSat Incorporated
• Inventors: Buer, Kenneth V., Miller, Mark J., Cronin, Christopher J., Dankberg, Mark D., Runyon, Donald L.
• Primary Examiner(s): Dean, Raymond S
• Application Number:
  US16/184,784
• Time in Patent Office: 264 Days
• Field of Search: None
• CPC Class Codes: H01Q 1/06 Means for the lighting or illuminating of antennas, e.g. for purpose of warning
• CPC Class Codes: H01Q 1/247 with frequency mixer, e.g. for direct satellite reception or Doppler radar
• CPC Class Codes: H01Q 1/288 Satellite antennas
• CPC Class Codes: H01Q 19/132 Horn reflector antennas; Off-set feeding
• CPC Class Codes: H01Q 21/0025 Modular arrays
• CPC Class Codes: H01Q 21/24 Combinations of antenna units polarised in different directions for transmitting or receiving circularly and elliptically polarised waves or waves linearly polarised in any direction circularly polarised patch antennas H01Q9/0428; circularly polarised horns H01Q13/0241; cross-polarised horns H01Q13/0258; polarisation converters H01Q15/242; cross-polarised rear feeds H01Q19/136; crossed polarisation dual antenna H01Q25/001
• CPC Class Codes: H01Q 25/001 Crossed polarisation dual antennas orthomode horns H01Q13/0258; cross-polarised rear feeds H01Q19/136; orthomode transducers H01P1/161
• CPC Class Codes: H01Q 3/247 by switching different parts of a primary active element
• CPC Class Codes: H01Q 3/40 with phasing matrix
• CPC Class Codes: H01Q 5/50 Feeding or matching arrangements for broad-band or multi-band operation
• CPC Class Codes: H04B 10/118 specially adapted for satellite communication
• CPC Class Codes: H04B 7/024 Co-operative use of antennas of several sites, e.g. in co-ordinated multipoint or co-operative multiple-input multiple-output [MIMO] systems
• CPC Class Codes: H04B 7/0413 MIMO systems
• CPC Class Codes: H04B 7/0617 for beam forming
• CPC Class Codes: H04B 7/18508 with satellite system used as relay, i.e. aeronautical mobile satellite service
• 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 7/18534 for enhancing link reliablility, e.g. satellites diversity
• 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 7/18586 : Arrangements for data transporting, e.g. for an end to end data transport or check
• CPC Class Codes: H04B 7/18589 : Arrangements for controlling an end to end session, i.e. for initialising, synchronising or terminating an end to end link
• CPC Class Codes: H04B 7/204 : Multiple access
• CPC Class Codes: H04B 7/2041 : Spot beam multiple access
• CPC Class Codes: H04W 16/26 : Cell enhancers or enhancement, e.g. for tunnels, building shadow
• CPC Class Codes: H04W 16/28 : using beam steering
• CPC Class Codes: H04W 4/00 : Services specially adapted for wireless communication networks; Facilities therefor
• CPC Class Codes: H04W 40/20 : based on geographic position or location
• CPC Class Codes: H04W 76/10 : Connection setup
• CPC Class Codes: H04W 84/06 : Airborne or Satellite Networks space-based or airborne stations H04B7/185
• CPC Class Codes: H05K 999/99 : dummy group

Abstract

Methods and systems are described for providing end-to-end beamforming. For example, end-to-end beamforming systems include end-to-end relays and ground networks to provide communications to user terminals located in user beam coverage areas. The ground segment can include geographically distributed access nodes and a central processing system. Return uplink signals, transmitted from the user terminals, have multipath induced by a plurality of receive/transmit signal paths in the end to end relay and are relayed to the ground network. The ground network, using beamformers, recovers user data streams transmitted by the user terminals from return downlink signals. The ground network, using beamformers generates forward uplink signals from appropriately weighted combinations of user data streams that, after relay by the end-end-end relay, produce forward downlink signals that combine to form user beams.

Claims

1. A system for providing a communication service to user terminals geographically distributed over a user coverage area via an end-to-end relay comprising multiple receive/transmit signal paths, comprising:

means for generating a forward beam weight matrix for end-to-end beamforming of transmissions from a set of access nodes to multiple forward user beam coverage areas of the user coverage area via the end-to-end relay, the set of access nodes comprising access nodes of at least one of a plurality of access node clusters, wherein each of the plurality of access node clusters comprises a plurality of access nodes at geographically distributed locations within a corresponding one of a plurality of access node areas;

means for generating, based on multiple forward beam signals comprising forward user data streams for transmission to a plurality of the user terminals grouped by the multiple forward user beam coverage areas, respective access node-specific forward signals for transmission from the set of access nodes to the multiple forward user beam coverage areas via the end-to-end relay, each of the respective access node-specific forward signals comprising a composite of at least a subset of the forward beam signals weighted by respective forward beamforming weights of the forward beam weight matrix; and

means for transmitting respective forward uplink signals from the set of access nodes based on the respective access node-specific forward signals, wherein the respective forward uplink signals are pre-corrected to compensate for respective path delays and phase shifts between the geographically distributed locations and the end-to-end relay.

2. The system of claim 1, wherein each of the plurality of access node areas is non-overlapping with other access node areas of the plurality of access node areas.

3. The system of claim 1, wherein at least one access node area of the plurality of access node areas is at least partially overlapping with at least one other access node area of the plurality of access node areas.

4. The system of claim 1, wherein at least one of the plurality of access node areas is at least partially overlapping with the user coverage area.

5. The system of claim 1, wherein at least one of the plurality of access node areas is non-overlapping with the user coverage area.

6. The system of claim 1, wherein at least one access node of at least one of the plurality of access node clusters is disposed on a mobile platform.

7. The system of claim 1, wherein the means for transmitting:

transmits a first set of forward uplink signals from a first access node cluster of the plurality of access node clusters to the end-to-end relay to be carried via a first set of the multiple receive/transmit signal paths; and

transmits a second set of forward uplink signals from a second access node cluster of the plurality of access node clusters to the end-to-end relay to be carried via a second set of the multiple receive/transmit signal paths.

8. The system of claim 7, wherein the means for generating the respective access node-specific forward signals generates the respective access node-specific forward signals to form at least one forward user beam for providing the communication service in least one of the multiple forward user beam coverage areas using at least a subset of the first set of forward uplink signals and at least a subset of the second set of forward uplink signals.

9. The system of claim 7, wherein the user coverage area comprises a first user coverage area and a second user coverage area and wherein the means for generating the respective access node-specific forward signals generates the respective access node-specific forward signals to form a first set of user beams from the first set of forward uplink signals and a second set of user beams from the second set of forward uplink signals, and wherein the respective sets of user beams provide the communication service in a respective user coverage area.

10. The system of claim 9, wherein the corresponding access node area of the first access node cluster is at least partially within the first user coverage area, and the corresponding access node area of the second access node cluster is at least partially within the second user coverage area.

11. The system of claim 9, wherein the corresponding access node area of the first access node cluster is outside the first user coverage area, and the corresponding access node area of the second access node cluster is outside the second user coverage area.

12. The system of claim 9, wherein the corresponding access node area of the first access node cluster is at least partially within the second user coverage area.

13. The system of claim 1, further comprising:

first selective coupling means for selectively coupling inputs of the multiple receive/transmit signal paths to one of a first array of cooperating feeder-link constituent antenna elements receiving a first set of forward uplink signals from a first access node cluster of the plurality of access node clusters or a second array of cooperating feeder-link constituent antenna elements receiving a second set of forward uplink signals from a second access node cluster of the plurality of access node clusters.

14. The system of claim 13, wherein the user coverage area comprises a first user coverage area and a second user coverage area, and further comprising:

second selective coupling means for selectively coupling the multiple receive/transmit signal paths to one of a first array of cooperating user-link constituent antenna elements associated with the first user coverage area or a second array of cooperating user-link constituent antenna elements associated with the second user coverage area.

15. The system of claim 14, wherein the first and second selective coupling means:

selectively couple the multiple receive/transmit signal paths between the first array of cooperating feeder-link constituent antenna elements and the first array of cooperating user-link constituent antenna elements during a first time period; and

selectively couple the multiple receive/transmit signal paths between the second array of cooperating feeder-link constituent antenna elements and the second array of cooperating user-link constituent antenna element during a second time period.

16. The system of claim 15, wherein the first and second selective coupling means include a first switch mode and a second switch mode, the first switch mode coupling the first array of cooperating feeder-link constituent antenna elements to the first array of cooperating user-link constituent antenna elements via the multiple receive/transmit signal paths, and the second switch mode coupling the second array of cooperating feeder-link constituent antenna elements to the second array of cooperating user-link constituent antenna elements via the multiple receive/transmit signal paths.

17. The system of claim 14, wherein the first user coverage area is non-overlapping with the corresponding access node area of the first access node cluster and the second user coverage area is non-overlapping with the corresponding access node area of the second access node cluster.

18. The system of claim 15, wherein:

the means for transmitting transmits, during the first time period, the first set of forward uplink signals from the plurality of access nodes of the first access node cluster over a first frequency range; and

the first array of cooperating user-link constituent antenna elements relays the first set of forward uplink signals to terminals within the first user coverage area over the first frequency range.

19. The system of claim 1, further comprising:

means for receiving, at each of the plurality of access nodes, a respective return downlink signal from the end-to-end relay, each of the respective return downlink signals comprising a composite of return uplink signals transmitted from a plurality of the user terminals and relayed by at least a subset of the multiple receive/transmit signal paths of the end-to-end relay to form a composite return signal;

means for generating a return beam weight matrix for end-to-end beamforming of transmissions from multiple return user beam coverage areas to the plurality of access node clusters via the end-to-end relay; and

means for obtaining respective return beam signals for the multiple return user beam coverage areas based on a matrix product of the return beam weight matrix and a vector of the respective composite return signals, wherein the respective composite return signals are corrected for timing and phase for respective path delays and phase shifts between the end-to-end relay and the plurality of access nodes.

20. The system of claim 1, further comprising:

means for distributing the plurality of access node-specific forward signals to the plurality of access nodes for each of the plurality of access node clusters.

21. A system for providing a communication service to user terminals geographically distributed over a user coverage area via an end-to-end relay comprising multiple receive/transmit signal paths, comprising:

means for receiving respective composite return signals from the end-to-end relay at a set of access nodes, each of the respective return downlink signals comprising return uplink signals transmitted from a plurality of the user terminals and relayed by the end-to-end relay to form a composite return signal, the set of access nodes comprising access nodes of at least one of a plurality of access node clusters, wherein each of the plurality of access node clusters comprises a plurality of access nodes at geographically distributed locations within a corresponding one of a plurality of access node areas;

means for applying, to each of the respective composite return signals, respective beamforming weights of a return beam weight matrix for end-to-end beamforming of transmissions from multiple return user beam coverage areas to the set of access nodes via the end-to-end relay to obtain a respective plurality of weighted composite return signals associated with each of the multiple return user beam coverage areas; and

means for combining, for the each of the multiple return user beam coverage areas, the respective plurality of weighted composite return signals to obtain a return beam signal associated with the each of the multiple return user beam coverage areas, wherein the respective plurality of weighted composite return signals are corrected to compensate for respective path delays and phase shifts between the end-to-end relay and the set of access nodes prior to the combining.

22. The system of claim 21, wherein each of the plurality of access node areas is non-overlapping with other access node areas of the plurality of access node areas.

23. The system of claim 21, wherein at least one access node area of the plurality of access node areas is at least partially overlapping with at least one other access node area of the plurality of access node areas.

24. The system of claim 21, wherein at least one of the plurality of access node areas is at least partially overlapping with the user coverage area.

25. The system of claim 21, wherein at least one of the plurality of access node areas is non-overlapping with the user coverage area.

26. The system of claim 21, wherein at least one access node of at least one of the plurality of access node clusters is disposed on a mobile platform.

27. The system of claim 21, wherein the means for receiving:

receives, at a first access node cluster of the plurality of access node clusters, a first set of return downlink signals corresponding to the return uplink signals carried via a first set of the multiple receive/transmit signal paths; and

receives, at a second access node cluster of the plurality of access node clusters a second set of return downlink signals corresponding to the return uplink signals carried via a second set of the multiple receive/transmit signal paths.

28. The system of claim 27, wherein the means for applying and the means for combining form at least one return user beam associated with at least one of the multiple return user beam coverage areas using at least a subset of the first set of return downlink signals and at least a subset of the second set of return downlink signals.

29. The system of claim 27, wherein the user coverage area comprises a first user coverage area and a second user coverage area and the means for applying and the means for combining form a first set of user beams associated with the first user coverage area from the first set of return downlink signals and form a second set of user beams associated with the second user coverage area from the second set of return downlink signals.

30. The system of claim 29, wherein the corresponding access node area of the first access node cluster is at least partially within the first user coverage area, and the corresponding access node area of the second access node cluster is at least partially within the second user coverage area.

31. The system of claim 29, wherein the corresponding access node area of the first access node cluster is outside the first user coverage area, and the corresponding access node area of the second access node cluster is outside the second user coverage area.

32. The system of claim 30, wherein the corresponding access node area of the first access node cluster is at least partially within the second user coverage area.

33. The system of claim 27, wherein the first set of the multiple receive/transmit signal paths are coupled with a first subset of antenna elements of an array of cooperating user-link constituent antenna elements and the second set of the multiple receive/transmit signal paths are coupled with a second subset of antenna elements of the array of cooperating user-link constituent antenna elements.

34. The system of claim 21, further comprising:

first selective coupling means for selectively coupling outputs of the multiple receive/transmit signal paths to one of a first array of cooperating feeder-link constituent antenna elements for transmitting a first set of return downlink signals to a first access node cluster of the plurality of access node clusters or a second array of cooperating feeder-link constituent antenna elements for transmitting a second set of return downlink signals to a second access node cluster of the plurality of access node clusters.

35. The system of claim 34, wherein the user coverage area comprises a first user coverage area and a second user coverage area, and further comprising:

second selective coupling means for selectively coupling inputs of the multiple receive/transmit signal paths to one of a first array of cooperating user-link constituent antenna elements associated with the first user coverage area or a second array of cooperating user-link constituent antenna elements associated with the second user coverage area.

36. The system of claim 35, wherein the first and second selective coupling means:

selectively couples the multiple receive/transmit signal paths between the first array of cooperating user-link constituent antenna elements and the first array of cooperating feeder-link constituent antenna elements during a first time period; and

selectively couples the multiple receive/transmit signal paths between the second array of cooperating user-link constituent antenna elements array and the second array of cooperating feeder-link constituent antenna elements during a second time period.

37. The system of claim 36, wherein the first and second selective coupling means include a first switch mode and a second switch mode, the first switch mode coupling the first array of cooperating feeder-link constituent antenna elements to the first array of cooperating user-link constituent antenna elements via the multiple receive/transmit signal paths, and the second switch mode coupling the second array of cooperating feeder-link constituent antenna elements to the second array of cooperating user-link constituent antenna elements via the multiple receive/transmit signal paths.

38. The system of claim 35, wherein the first user coverage area is non-overlapping with the corresponding access node area of the first access node cluster and the second user coverage area is non-overlapping with the corresponding access node area of the second access node cluster.

39. The system of claim 21, further comprising:

means for obtaining the respective composite return signals from the plurality of access nodes for each of the plurality of access node clusters.