GROUND NETWORK WITH ACCESS NODE CLUSTERS FOR END-TO-END BEAMFORMING

• US 20180019804A1
• Filed: 09/28/2017
• Published: 01/18/2018
• 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.
• Granted Patent: US 10,142,011 B2
• Time in Patent Office: Days
• 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:

a beam signal interface that obtains multiple forward beam signals comprising forward user data streams for transmission to the user terminals grouped by multiple forward user beam coverage areas;

a beam weight generator that generates a forward beam weight matrix for end-to-end beamforming to the multiple forward user beam coverage areas via the end-to-end relay;

a beamformer coupled with the beam signal interface and the beam weight generator, the beamformer comprising a forward matrix multiplier that obtains a plurality of access-node specific forward signals based on a matrix product of the forward beam weight matrix and a vector of the forward beam signals; and

a plurality of access node clusters, wherein each access node cluster is associated with a corresponding one of a plurality of access node areas, and wherein each of the plurality of access node clusters comprises;

a plurality of access nodes geographically distributed within the corresponding access node area, wherein each access node cluster obtains a respective set of the plurality of access node-specific forward signals, and wherein each of the plurality of access nodes of the each access node cluster comprises a transmitter that transmits a respective forward uplink signal to the end-to-end relay based on one of the respective set of the plurality of access node-specific forward signals, and wherein the respective forward uplink signals are pre-corrected to compensate for respective path delays and phase shifts introduced between the plurality of access nodes 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 of the plurality of access node areas is non-overlapping with the user coverage area.

4. The system of claim 1, wherein a first set of forward uplink signals from a first access node cluster of the plurality of access node clusters are carried via a first set of the multiple receive/transmit signal paths and a second set of forward uplink signals from a second access node cluster of the plurality of access node clusters are carried via a second set of the multiple receive/transmit signal paths.

5. The system of claim 4, wherein the first set of forward uplink signals and the second set of forward uplink signals both contribute to forming at least one forward user beam associated with at least one of the multiple forward user beam coverage areas.

6. The system of claim 4, wherein:

the first set of the multiple receive/transmit signal paths are coupled with a first array of cooperating user-link constituent antenna elements of a user-link antenna subsystem of the end-to-end relay, and the second set of the multiple receive/transmit signal paths are coupled with a second array of cooperating user-link constituent antenna elements of the user-link antenna subsystem;

the user coverage area comprises a first user coverage area and a second coverage area;

the first array of cooperating user-link constituent antenna elements is associated with the first user coverage area; and

the second array of cooperating user-link constituent antenna elements is associated with the second user coverage area.

7. The system of claim 1, wherein the multiple receive/transmit signal paths are selectively coupled via a first set of switches to one of a first array of cooperating feeder-link constituent antenna elements associated with a first access node cluster of the plurality of access node clusters or a second array of cooperating feeder-link constituent antenna elements associated with a second access node cluster of the plurality of access node clusters.

8. 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 multiple receive/transmit signal paths are selectively coupled via a second set of switches 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.

9. The system of claim 8, 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.

10. The system of claim 1, wherein:

each of the plurality of access nodes comprises a receiver that receives a respective return downlink signal from the end-to-end relay via an antenna, 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;

the beam weight generator generates 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

the beamformer comprises a return matrix multiplier that obtains 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.

11. A method 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:

obtaining multiple forward beam signals comprising forward user data streams for transmission to a plurality of the user terminals grouped by multiple forward user beam coverage areas;

identifying a forward beam weight matrix for end-to-end beamforming of transmissions from a set of access nodes to the multiple forward user beam coverage areas 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;

generating respective access node-specific forward signals for transmission by the set of access nodes, each of the respective access node-specific forward signals comprising a composite of respective forward beam signals weighted by respective forward beamforming weights of the forward beam weight matrix; and

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 plurality of access nodes and the end-to-end relay.

12. The method of claim 11, wherein the transmitting comprises:

transmitting 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

transmitting 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.

13. The method of claim 12, further comprising:

forming at least one forward user beam for providing the communication service in at 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.

14. The method of claim 12, wherein the user coverage area comprises a first user coverage area and a second user coverage area and further comprising forming a first set of user beams for providing the communication service in the first user coverage area from the first set of forward uplink signals and forming a second set of user beams for providing the communication service in the second user coverage area from the second set of forward uplink signals.

15. The method of claim 11, further comprising:

selectively coupling inputs of the multiple receive/transmit signal paths to a first array of cooperating feeder-link constituent antenna elements associated with a first access node cluster of the plurality of access node clusters during a first time period; and

selectively coupling inputs of the multiple receive/transmit signal paths to a second array of cooperating feeder-link constituent antenna elements associated with a second access node cluster of the plurality of access node clusters during a second time period.

16. The method of claim 15, wherein the user coverage area comprises a first user coverage area and a second user coverage area, and further comprising:

selectively coupling outputs of the multiple receive/transmit signal paths to a first array of cooperating user-link constituent antenna elements associated with the first user coverage area during the first time period; and

selectively coupling outputs of the multiple receive/transmit signal paths to a second array of cooperating user-link constituent antenna elements associated with the second user coverage area during the second time period.

17. The method of claim 11, further comprising:

receiving, by a receiver 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;

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

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.

18. 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:

a plurality of access node clusters, wherein each access node cluster is associated with a corresponding one of a plurality of access node areas, and wherein each of the plurality of access node clusters comprises;

a plurality of access nodes geographically distributed within the corresponding access node area, each of the plurality of access nodes comprising a receiver that receives 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;

a beam weight generator that generates 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

a return beamformer coupled with the beam weight generator, the return beamformer comprising a matrix multiplier that obtains 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.

19. The system of claim 18, wherein a first access node cluster of the plurality of access node clusters receives 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 a second access node cluster of the plurality of access node clusters receives 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.

20. The system of claim 19, wherein the first set of return downlink signals and the second set of return downlink signals both contribute to forming at least one return user beam associated with at least one of the multiple return user beam coverage areas.

21. The system of claim 19, wherein:

inputs of the first set of the multiple receive/transmit signal paths are coupled with a first array of cooperating user-link constituent antenna elements of a user-link antenna subsystem of the end-to-end relay, and inputs of the second set of the multiple receive/transmit signal paths are coupled with a second array of cooperating user-link constituent antenna elements of the user-link antenna subsystem;

the user coverage area comprises a first user coverage area and a second coverage area;

the first array of cooperating user-link constituent antenna elements is associated with the first user coverage area; and

the second array of cooperating user-link constituent antenna elements is associated with the second user coverage area.

22. The system of claim 18, wherein the multiple receive/transmit signal paths are selectively coupled via a first set of switches 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.

23. The system of claim 22, wherein the user coverage area comprises a first user coverage area and a second user coverage area, and wherein the multiple receive/transmit signal paths are selectively coupled via a second set of switches 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.

24. The system of claim 23, 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.

25. A method 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, the method comprising:

receiving, at a set of access nodes, respective return downlink signals from the end-to-end relay, each of the respective return downlink signals comprising return user data streams 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;

identifying 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;

applying, to each of the respective composite return signals, respective beamforming weights of the return beam weight matrix to obtain a respective plurality of weighted composite return signals associated with each of the multiple return user beam coverage areas; and

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.

26. The method of claim 25, wherein the receiving comprises:

receiving, 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

receiving, 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.

27. The method of claim 26, further comprising:

forming 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.

28. The method of claim 26, wherein the user coverage area comprises a first user coverage area and a second user coverage area, the method further comprising:

forming a first set of return user beams associated with the first user coverage area from the first set of return downlink signals and forming a second set of return user beams associated with the second user coverage area from the second set of return downlink signals.

29. The method of claim 25, wherein the user coverage area comprises a first user coverage area and a second user coverage area, and further comprising:

selectively coupling inputs of the multiple receive/transmit signal paths to a first array of cooperating user-link constituent antenna elements associated with the first user coverage area during a first time period; and

selectively coupling the multiple receive/transmit signal paths to a second array of cooperating user-link constituent antenna elements associated with the second user coverage area during a second time period.

30. The method of claim 29, further comprising:

selectively coupling outputs of the multiple receive/transmit signal paths to a first array of cooperating feeder-link constituent antenna elements associated with a first access node cluster of the plurality of access node clusters during the first time period; and

selectively coupling outputs of the multiple receive/transmit signal paths to a second array of cooperating feeder-link constituent antenna elements associated with a second access node cluster of the plurality of access node clusters during the second time period.