End-to-end beamforming systems and satellites

Abstract

The present invention provides an end-to-end beam forming method and apparatus. [Solution] An end-to-end beamforming system 500 for providing communication to a user terminal 517 located within a user beam coverage area 519, wherein the ground segment includes geographically distributed access nodes 515 and a central processing system 505. A return uplink signal 525 transmitted from the user terminal has a multiplexed path induced by multiple receive / transmit signal paths of end-to-end relays and is relayed to a ground network 502, which uses a beamformer 513 to reconstruct the user data stream transmitted by the user terminal from the return downlink signal 527, generates a forward downlink signal 522 to form a user beam after relaying by end-to-end relays, and generates a forward link signal 521 from a combination of appropriately weighted user data streams.

Claims

1. An end-to-end beamforming system (500, 1200, 3400), Multiple geographically distributed access nodes (515), each having an end-to-end beam-weighted forward uplink signal output, An end-to-end relay (503, 1202, 1502, 3403) having multiple receive / transmit signal paths (1702), wherein each receive / transmit signal path is A receiving antenna element (406, 3416) wirelessly communicates with the multiple beam-weighted forward uplink signal outputs via each of the multiple uplinks, A transponder (410, 3430) that communicates with the receiving antenna element, The system includes an end-to-end relay comprising transmission antenna elements (409, 3429) that communicate with each of the transponders via one of a plurality of downlinks and also wirelessly communicate with user terminals in the forward user beam coverage area, Therefore, the superposition of the multiple beam-weighted forward uplink signals received via the uplink creates a composite input forward signal at each receiving antenna element. Therefore, the multiple forward downlink signals transmitted by the multiple transmission antenna elements form the forward user beam in an end-to-end beamforming system (500, 1200, 3400).

2. The end-to-end beamforming system according to claim 1, further comprising a user terminal (517) positioned within a forward user beam coverage area serviced by the forward user beam, and communicating downlink with the plurality of receiving / transmitting signal paths via the downlink to receive the superimposed forward downlink signals.

3. The aforementioned forward user beam is one of a plurality of forward user beams, each corresponding to a forward user beam coverage area that provides service to each set of user terminals. The end-to-end beamforming system according to claim 1 or 2, wherein each of the composite forward downlink signals transmitted by the transmission antenna element forms the plurality of forward user beams.

4. The end-to-end beamforming system according to claim 3, wherein there are more forward user beams than transponders.

5. The end-to-end beamforming system according to claim 3 or 4, wherein the number of access nodes is not equal to the number of forward user beams.

6. Multiple access nodes comprise a first subset of access nodes and a second subset of access nodes. The forward user beam is the first forward user beam, A first subset of the access nodes comprises a beam-weighted forward uplink signal output associated with the first forward user beam, The end-to-end beamforming system according to any one of claims 1 to 5, wherein the second subset of the access nodes comprises beam-weighted forward uplink signal outputs associated with a second forward user beam.

7. The end-to-end beamforming system according to claim 6, wherein at least one access node is located in both the first and second subsets.

8. A beam weighting generator (910, 917) equipped with a beam weighting value output, Forward beamformer (513, 529, 3006), A beam weighting value input (920) communicates with the beam weighting value output to receive a set of forward beam weighting values, A data input (925) for receiving the forward beam signal, The system further includes a forward beamformer having an output (923) that communicates with the aforementioned plurality of access nodes, An end-to-end beamforming system according to any one of claims 1 to 7, wherein each access node receives one of the beam-weighted forward uplink signals from the output of the forward beamformer.

9. The end-to-end beamforming system according to claim 8, further comprising a distribution network (518) that communicates with the forward beamformer and the access node.

10. The end-to-end beamforming system according to claim 8 or 9, wherein each beam-weighted forward uplink signal is generated by applying the set of forward beam weights to the forward beam signal, and so each beam-weighted forward uplink signal is unique to each of the plurality of access nodes.

11. A channel estimator (919) having an estimated end-to-end channel gain signal associated with an end-to-end forward multiplexed path channel, further comprising a channel estimator that connects the access node to the user terminal in the forward user beam coverage area via the transponder of the end-to-end forward multiplexed path channel, The end-to-end beamforming system according to any one of claims 8 to 10, wherein the beam weighting generator communicates with the estimated end-to-end channel gain signal, and the beam weighting generator has a set of forward beam weights determined as a function of the estimated end-to-end channel gain signal.

12. The channel estimator, A downlink radiation matrix (At) models the downlink path from the transmission antenna element to the user terminal. A payload matrix (E) that models the aforementioned transponder, The system includes a channel data store (921) which stores an uplink radiation matrix (Cr) that models the uplink path from the access node to the receiving antenna element, The end-to-end beamforming system according to claim 11, wherein the end-to-end channel gain output is estimated to form a forward channel matrix (At × E × Cr).

13. The end-to-end beamforming system according to claim 12, further comprising a deployed non-ground craft on which the end-to-end relay is positioned, wherein at least one of At, E, or Cr is estimated after the deployment of the craft.

14. The end-to-end beamforming system according to claim 13, wherein E is measured with respect to the end-to-end relay before the deployment of the craft.

15. The end-to-end beamforming system according to claim 12 or 13, wherein the forward channel matrix is ​​estimated and stored in the channel data store before the forward beam signal is received.

16. An end-to-end beamforming system according to any one of claims 1 to 15, wherein there are more access nodes than transponders.

17. The end-to-end beamforming system according to any one of claims 1 to 16, wherein the forward beam signal is formed by multiplexing a plurality of user data streams according to at least one of time-division multiplexing or frequency-division multiplexing, and each of the plurality of user data streams is for transmission to at least one of a plurality of user terminals that are serviced by the forward user beam.

18. The access node and the user terminal are Earth terminals, The end-to-end beam forming system according to any one of claims 1 to 17, wherein the end-to-end relay is located on a non-ground craft.

19. The aforementioned access node is a satellite access node, The end-to-end beamforming system according to any one of claims 1 to 18, wherein the end-to-end relay is located on a satellite.

20. The user terminal is further located within the return path user beam coverage area and has an antenna for transmitting the return path uplink signal, and the return path uplink signal includes the return path beam signal. Each of the receiving / transmitting signal paths communicates wirelessly with the user terminal to generate multiple return downlink signals from each of the multiple receptions of the return uplink signals. Each of the access nodes communicates wirelessly with the receiving / transmitting signal path via its respective return downlink path to receive the superimposed return downlink signal (1706) and form a composite return signal (907). The end-to-end beamforming system further comprises return beamformers (513, 531, 3016), and the return beamformer is The system communicates with the access node to receive a composite return path signal, and each composite return path signal includes the respective return path downlink signal received by one of the access nodes, and the return path signal input An end-to-end beamforming system according to any one of claims 1 to 19, comprising a beamforming output for communicating the beamformed combination of the composite return path signals.

21. The access node communicates uplink with the end-to-end relay through the frequency band. The end-to-end beamforming system according to claim 20, wherein the user terminal communicates uplink with the end-to-end relay through the frequency band.

22. These are satellites (503, 1202, 1502, 3403), A plurality of receiving antenna elements (406, 3416, 3426) each having a receiving component beam antenna pattern such that at least one of the receiving component beam antenna patterns overlaps with at least one of the receiving component beam antenna patterns, and which can operate at the same receiving frequency and the same receiving polarization, A plurality of transmission antenna elements (409, 3419, 3429) each having a transmission element beam antenna pattern such that at least one of the transmission element beam antenna patterns overlaps with at least one of the transmission element beam antenna patterns, and which are capable of operating at the same transmission frequency and the same transmission polarization, A satellite comprising a plurality of transponders (410, 3430, 3440), each having an input that is coupled to the associated receiving antenna element and an output that is coupled to the associated transmitting antenna element, such that there is a one-to-one relationship between each transponder, the associated receiving antenna element and the associated transmitting antenna element.

23. The satellite according to claim 22, wherein at least 25% of each of the constituent beam antenna patterns overlaps with at least five of the receiving constituent beam antenna patterns.

24. The satellite according to claim 22 or 23, wherein each of at least 25% of the transmission component beam antenna patterns overlaps with at least five other transmission component beam antenna patterns.

25. The satellite according to any one of claims 22 to 24, having an uplink satellite coverage area defined by a set of points, wherein the receiving component beam antenna pattern of each receiving antenna element establishes a corresponding receiving antenna element coverage area, and at least 25% of the set of points in the uplink satellite coverage area covers at least four of the receiving antenna element coverage areas.

26. The satellite according to claim 25, wherein at least 25% of the points in the uplink satellite coverage area fall within at least six of the receiving antenna element coverage areas.

27. The satellite according to any one of claims 22 to 26, wherein each receiving antenna element coverage area is defined by a set of points where the receiving element beam antenna gain is within 10 dB of the peak receiving element beam antenna gain of the receiving antenna element associated with the receiving antenna element coverage area.

28. The satellite according to any one of claims 22 to 26, wherein each receiving antenna element coverage area is defined by a set of points where the receiving element beam antenna gain is within 6 dB of the peak receiving element beam antenna gain of the receiving antenna element associated with the receiving antenna element coverage area.

29. The satellite according to any one of claims 22 to 26, wherein each receiving antenna element coverage area is defined by a set of points where the receiving element beam antenna gain is within 3 dB of the peak receiving element beam antenna gain of the receiving antenna element associated with the receiving antenna element coverage area.

30. The satellite according to any one of claims 22 to 29, having a downlink satellite coverage area defined by a set of points such that the transmission component beam antenna pattern of each transmission antenna element establishes a corresponding transmission antenna element coverage area of ​​the transmission antenna element, and at least 25% of the set of points in the downlink satellite coverage area covers at least four of the transmission antenna element coverage areas.

31. The satellite according to claim 30, wherein at least 25% of the set of points in the downlink satellite coverage area falls within at least six of the transmission antenna element coverage areas.

32. The satellite according to claim 30 or 31, wherein each transmission antenna element coverage area is defined by a set of points where the beam antenna gain of the transmission element is within 10 dB of the peak beam antenna gain of the transmission antenna element associated with the transmission antenna element coverage area.

33. The satellite according to claim 30 or 31, wherein each transmission antenna element coverage area is defined by a set of points where the beam antenna gain of the transmission element is within 6 dB of the peak beam antenna gain of the transmission antenna element associated with the transmission antenna element coverage area.

34. The satellite according to claim 30 or 31, wherein each transmission antenna element coverage area is defined by a set of points where the beam antenna gain of the transmission element is within 3 dB of the peak beam antenna gain of the transmission antenna element associated with the transmission antenna element coverage area.

35. The satellite according to any one of claims 22 to 34, further comprising receiving reflectors (1521, 1621), wherein the plurality of receiving antenna elements are arranged to receive signals reflected by the receiving reflectors.

36. The satellite according to claim 35, wherein the receiving reflector (1621) has a focal plane (1625), and the plurality of receiving antenna elements are positioned outside the focal plane of the receiving reflector.

37. The satellite according to any one of claims 22 to 34, wherein the plurality of receiving antenna elements are arranged as a direct radiation array.

38. The satellite according to any one of claims 22 to 37, wherein each of the plurality of transponders is coupled between the sole receiving antenna element associated with it and the sole transmitting antenna element associated with it.

39. The satellite according to any one of claims 22 to 38, further comprising transmission reflectors (1521, 1561), wherein the plurality of transmission antenna elements are arranged to illuminate the transmission reflectors.

40. The satellite according to claim 39, wherein the transmission reflector (1621) has a focal plane (1625), and the plurality of transmission antenna elements are positioned outside the focal plane of the transmission reflector.

41. The satellite according to any one of claims 22 to 38, wherein the plurality of transmission antenna elements are arranged as a direct radiation array.

42. Each transponder, An LNA (412, 3705) having a low-noise amplifier (LNA) input and an LNA output, wherein the LNA input is coupled to one of the associated receiving antenna elements, A satellite according to any one of claims 22 to 41, comprising a PA (420, 3725) having a power amplifier (PA) input coupled to the LNA output and a PA output coupled to one of the associated transmission antenna elements.

43. The satellite according to claim 42, wherein at least one of the plurality of transponders further comprises a frequency converter (414, 3710) coupled between the LAN and the PA.

44. The satellite according to any one of claims 22 to 43, wherein at least one of the plurality of transponders is a forward link transponder (3430), and at least one of the plurality of transponders is a return link transponder (3440).

45. The satellite according to any one of claims 22 to 44, wherein the plurality of transponders comprises 10 transponders.

46. The satellite according to any one of claims 22 to 45, wherein the plurality of transponders comprises 100 transponders.

47. The satellite according to any one of claims 22 to 46, wherein at least one of the transponders operates in a frequency band selected from the group consisting of C, L, S, X, V, Ka, and Ku.

48. The satellite according to any one of claims 22 to 47, wherein at least one of the transponders operates in a frequency bandwidth selected from the group consisting of 500 MHz, 1 GHz, 1.5 GHz, 2 GHz, 2.5 GHz, 3 GHz, and 3.5 GHz.

49. The satellite according to any one of claims 22 to 48, further comprising a beacon generator (426).

50. The satellite according to claim 49, wherein the beacon generator is coupled to at least one of the plurality of transmission antenna elements.

51. The satellite according to claim 49 or 50, wherein the satellite beacon generator generates satellite beacons having a pseudo-random sequence.

52. The satellite according to any one of claims 22 to 51, wherein the satellite is a geostationary satellite.

53. The satellite according to any one of claims 22 to 52, wherein the plurality of receiving antenna elements receive signals from the Earth transmitter at a plurality of received signal levels, and at least a subset of the plurality of receiving antenna elements receive the signals from the Earth transmitter at a received signal level in which all are within 10 dB of the maximum value of the plurality of received signal levels.

54. The satellite according to claim 53, wherein the subset comprises 10% of the plurality of receiving antenna elements.

55. The satellite according to claim 53 or 54, wherein the subset comprises 10 of the plurality of receiving antenna elements.

56. The satellite according to any one of claims 22 to 55, wherein the plurality of transmission antenna elements transmit signals to an Earth receiver at a plurality of transmission signal levels, and at least a subset of the plurality of transmission antenna elements transmit the signals to the Earth receiver at a transmission signal level in which all are within 10 dB of the maximum value of the plurality of transmission signal levels.

57. The satellite according to claim 56, wherein the subset comprises 10% of the plurality of transmission antenna elements.

58. The satellite according to claim 56 or 57, wherein the subset comprises 10 of the plurality of transmission antenna elements.

59. The satellite according to any one of claims 22 to 58, wherein the signal path time delays between the plurality of transponders are matched.

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