Cross-band system for end-to-end beamforming

• US 10,187,141 B2
• Filed: 09/25/2017
• Issued: 01/22/2019
• Est. Priority Date: 04/10/2015
• Status: Active Grant

• Current Assignee: ViaSat Incorporated
• Original Assignee: ViaSat Incorporated
• Inventors: Buer, Kenneth V., Miller, Mark J.
• Primary Examiner(s): Magloire, Vladimir
• Assistant Examiner(s): Pervin, Nuzhat
• Application Number:
  US15/714,203
• Publication Number:
  US 20180026710A1
• Time in Patent Office: 484 Days
• Field of Search: 342354
• 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, 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;

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;

access node beacon generators that generate access node beacon signals;

a plurality of access nodes geographically distributed within an access node area, wherein each of the plurality of access nodes comprises a transmitter that transmits a respective one of the access node beacon signals and transmits a respective forward uplink signal over a feeder uplink frequency range based on a respective one of the plurality of access node-specific forward signals, and wherein the plurality of access nodes comprise receivers that receive return downlink signals over a feeder downlink frequency range;

an end-to-end relay comprising multiple receive/transmit signal paths that receives forward composite uplink signals at inputs of the multiple receive/transmit signal paths and transmits forward downlink signals from outputs of the multiple receive/transmit signal paths over a user downlink frequency range that is non-overlapping with the feeder downlink frequency range, wherein each of the forward composite uplink signals is a superposition of at least a subset of the forward uplink signals, and wherein the end-to-end relay comprises a loopback signal path that relays the access node beacon signals in the feeder downlink frequency range; and

transmit timing and phase compensators that pre-correct the respective forward uplink signals to compensate for respective path delays and phase shifts introduced between the plurality of access nodes and the end-to-end relay based at least in part on the relayed access node beacon signals.

2. The system of claim 1, wherein the access node area has a physical area that is smaller than a physical area of the user coverage area.

3. The system of claim 1, wherein the access node area is non-overlapping with the user coverage area.

4. The system of claim 3, wherein the access node area has a physical area that is smaller than a physical area of the user coverage area.

5. A satellite for providing communications between a plurality of access nodes geographically distributed over an access node area and a plurality of user terminals geographically distributed over a user coverage area, the satellite comprising:

a feeder-link antenna subsystem to illuminate the access node area, wherein the feeder-link antenna subsystem comprises a feeder-link element array, the feeder-link element array comprising an array of cooperating feeder-link constituent transmit elements and an array of cooperating feeder-link constituent receive elements;

a user-link antenna subsystem to illuminate the user coverage area, the user-link antenna subsystem comprising a user-link element array, the user-link element array comprising an array of cooperating user-link constituent transmit elements and an array of cooperating user-link constituent receive elements;

a plurality of forward-link transponders, each of the plurality of forward-link transponders receiving a forward composite uplink signal over a first frequency range via a respective one of the feeder-link constituent receive elements and transmitting a forward downlink signal over a second frequency range via a respective one of the user-link constituent transmit elements, wherein the forward composite uplink signal is a superposition of at least a subset of a plurality of forward uplink signals transmitted by respective access nodes of the plurality of access nodes, and wherein each of the plurality of forward uplink signals comprises a respective access node beacon signal;

a plurality of return-link transponders, each of the plurality of return-link transponders receiving a return composite uplink signal over a third frequency range via a respective one of the user-link constituent receive elements and transmitting a return downlink signal over a fourth frequency range via a respective one of the feeder-link constituent transmit elements, wherein the fourth frequency range is non-overlapping with the second frequency range; and

a loopback transponder that relays the access node beacon signals over the fourth frequency range.

6. The satellite of claim 5, wherein the access node area has a physical area that is smaller than a physical area of the user coverage area.

7. The satellite of claim 5, wherein the access node area is non-overlapping with the user coverage area.

8. The satellite of claim 7, wherein the access node area has a physical area that is smaller than a physical area of the user coverage area.

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

generating respective access node-specific forward signals for transmission by the plurality 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 plurality of access nodes to the end-to-end relay over a first frequency range, the respective forward uplink signals comprising the respective access node-specific forward signals and respective access node beacon signals;

receiving, at the plurality of access nodes, return downlink signals over a second frequency range;

receiving, at the end-to-end relay, forward composite uplink signals at inputs of the multiple receive/transmit signal paths over the first frequency range, wherein each of the forward composite uplink signals is a superposition of at least a subset of the forward uplink signals;

transmitting, from the end-to-end relay, forward downlink signals from outputs of the multiple receive/transmit signal paths over a third frequency range,

relaying, from the end-to-end relay, the access node beacon signals over the second frequency range, wherein the third frequency range is non-overlapping with the second frequency range;

pre-correcting the respective forward uplink signals to compensate for respective path delays and phase shifts between the plurality of access nodes and the end-to-end relay based at least in part on the relayed access node beacon signals.

10. The method of claim 9, wherein the access node area has a physical area that is smaller than a physical area of the user coverage area.

11. The method of claim 9, wherein the access node area is non-overlapping with the user coverage area.

12. The method of claim 11, wherein the access node area has a physical area that is smaller than a physical area of the user coverage area.