ACCESS NODE FARM FOR END-TO-END BEAMFORMING

• US 20180019805A1
• 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.
• Granted Patent: US 10,084,532 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

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 comprising multiple forward user beam coverage areas via an end-to-end relay comprising multiple forward receive/transmit signal paths, comprising:

a plurality of access nodes geographically distributed within an access node area having a physical area that is smaller than a physical area of the user coverage area, the plurality of access nodes transmitting respective access node-specific forward signals to the end-to-end relay, each of the respective access node-specific forward signals comprising a composite of respective forward beam signals weighted by respective forward beamforming weights of a forward beam weight matrix for end-to-end beamforming of transmissions from the plurality of access nodes to the multiple forward user beam coverage areas via the end-to-end relay, each access node of the plurality of access nodes comprising;

a network interface that obtains one of the respective access node-specific forward signals;

a transmitter that transmits a forward uplink signal comprising the one of the respective access node-specific forward signals to the end-to-end relay; and

a controller that pre-corrects the forward uplink signal to compensate for a path delay and a phase shift introduced between the access node and the end-to-end relay.

2. The system of claim 1, wherein the access node area at least partially overlaps with a low demand area of the user coverage area.

3. The system of claim 2, wherein the low demand area of the user coverage area comprises an area in which the demand for the communication service is below a demand threshold.

4. The system of claim 1, further comprising a distribution network that distributes the plurality of access node-specific forward signals.

5. The system of claim 1, wherein the access node area is contained within the user coverage area.

6. The system of claim 1, wherein the physical area of the access node area is less than one half of the physical area of the user coverage area.

7. The system of claim 1, wherein the physical area of the access node area is less than one-fifth of the physical area of the user coverage area.

8. The system of claim 1, wherein the physical area of the access node area is less than one-tenth of the physical area of the user coverage area.

9. The system of claim 1, wherein the access node area is a single contiguous coverage area.

10. The system of claim 1, wherein each access node of the plurality of access nodes comprises:

a receiver that receives a return downlink signal from the end-to-end relay, the return downlink signal comprising a relay beacon signal and return uplink signals from a plurality of the user terminals relayed by the end-to-end relay, to form a composite return signal;

a relay beacon signal demodulator that demodulates the relay beacon signal to obtain relay timing information; and

a multiplexer that multiplexes the composite return signal with the relay timing information to obtain a multiplexed composite return signal,

wherein the network interface sends the multiplexed composite return signal to a return beamformer.

11. 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 forward receive/transmit signal paths, comprising:

a forward beamformer 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 and generates a plurality of access-node specific forward signals based on a matrix product of a forward beam weight matrix for end-to-end beamforming of transmissions from an access node area that is at least partially overlapping with an aquatic body to the multiple forward user beam coverage areas via the end-to-end relay and a vector of the forward beam signals; and

a plurality of access nodes geographically distributed within the access node area, wherein each of the plurality of access nodes obtains a respective one of the plurality of access node-specific forward signals, and wherein each of the plurality of access nodes comprises a transmitter that transmits a respective forward uplink signal to the end-to-end relay based on the respective access node-specific forward signal, 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, and wherein at least one of the plurality of access nodes is located within the aquatic body.

12. The system of claim 11, wherein the at least one of the plurality of access nodes is located on a floating platform in the aquatic body.

13. The system of claim 11, further comprising a distribution network that distributes the plurality of access node-specific forward signals.

14. The system of claim 13, wherein the distribution network comprises a submarine cable coupled with the forward beamformer and the at least one of the plurality of access nodes.

15. The system of claim 13, wherein the distribution network comprises a free space optical link that couples the forward beamformer and the at least one of the plurality of access nodes.

16. The system of claim 13, wherein the forward beamformer or the distribution network are located within the aquatic body.

17. The system of claim 11, wherein the aquatic body comprises an ocean.

18. The system of claim 11, wherein the user coverage area comprises a terrestrial land mass.

19. The system of claim 11, wherein the access node area is at least partially overlapping with the user coverage area.

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

a plurality of access nodes disposed on respective mobile platforms within a first access node area having a physical area that is smaller than a physical area of the user coverage area, the plurality of access nodes transmitting respective access node-specific forward signals to the end-to-end relay, each of the respective access node-specific forward signals comprising a composite of respective forward beam signals weighted by respective forward beamforming weights of a first forward beam weight matrix for end-to-end beamforming of transmissions from the plurality of access nodes disposed at first locations within the first access node area to the multiple forward user beam coverage areas via the end-to-end relay, each access node of the plurality of access nodes comprising;

a network interface that obtains one of the respective access node-specific forward signals;

a transmitter that transmits a forward uplink signal comprising the one of the respective access node-specific forward signals to the end-to-end relay; and

a controller that pre-corrects the forward uplink signal to compensate for a path delay and a phase shift introduced between the access node and the end-to-end relay.

21. The system of claim 20, further 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 the first forward beam weight matrix for end-to-end beamforming from the first locations within the first access node area to the multiple forward user beam coverage areas via the end-to-end relay; and

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

22. The system of claim 21, wherein:

at least one of the plurality of access nodes changes location within the first access node area; and

the beam weight generator generates a second forward beam weight matrix for end-to-end beamforming from second locations of the plurality of access nodes within the first access node area in response to the change in location of the at least one of the plurality of access nodes.

23. The system of claim 21, wherein:

at least a subset of the plurality of access nodes change locations such that locations of the plurality of access nodes define a second access node area that is different than the first access node area; and

the beam weight generator generates a second forward beam weight matrix for end-to-end beamforming from second locations of the plurality of access nodes within the second access node area.

24. The system of claim 23, wherein the change in location of the at least the subset of the plurality of access nodes is in response to a change in location of the end-to-end relay.

25. The system of claim 21, wherein the beamformer is disposed on a mobile processing platform located proximate to the first access node area.

26. The system of claim 20, further comprising:

a distribution network that distributes the plurality of access node-specific forward signals to the plurality of access nodes on the respective mobile platforms.

27. A method of communication at an access node of a communication system comprising a plurality of access nodes at geographically distributed locations providing a communication service to user terminals geographically distributed over multiple forward user beam coverage areas via an end-to-end relay comprising multiple forward receive/transmit signal paths, the method comprising:

obtaining, while the access node is at a first location, a first access node-specific forward signal for transmission via the end-to-end relay to a plurality of the user terminals grouped by the multiple forward user beam coverage areas, the first access node-specific forward signal comprising a composite of first forward beam signals corresponding to a plurality of the multiple forward user beam coverage areas, the first forward beam signals weighted by respective beam weights of a first beam weight vector associated with the first location;

synchronizing a first forward uplink signal for reception at the end-to-end relay time and phase aligned with a first group of other forward uplink signals from other access nodes of the plurality of access nodes;

transmitting the first forward uplink signal comprising the first access node-specific forward signal to the end-to-end relay;

changing from the first location to a second location;

obtaining, while the access node is at the second location, a second access node-specific forward signal for transmission via the end-to-end relay to the plurality of the user terminals grouped by the multiple forward user beam coverage areas, the second access node-specific forward signal comprising a composite of second forward beam signals corresponding to the plurality of the multiple forward user beam coverage areas, the second forward beam signals weighted by respective beam weights of a second beam weight vector associated with the second location;

synchronizing a second forward uplink signal for reception at the end-to-end relay time and phase aligned with a second group of other forward uplink signals from the other access nodes of the plurality of access nodes; and

transmitting the second forward uplink signal comprising the second access node-specific forward signal to the end-to-end relay.

28. The method of claim 27, wherein the synchronizing comprises:

identifying forward uplink signal transmit timing information indicating transmission timing in the respective access node-specific forward signal;

transmitting an access node beacon signal to the end-to-end relay;

receiving signaling from the end-to-end relay comprising a loopback beacon signal; and

adjusting the forward uplink signal transmit timing information to time and phase align the respective forward uplink signal with the respective group of other forward uplink signals.

29. The method of claim 27, wherein the changing from the first location to the second location is in response to a change in location of the end-to-end relay.

30. The method of claim 27, wherein first and second access node-specific forward signals are obtained from a forward beamformer via a free space optical link.