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EP-4742558-A2 - COVERAGE AREA ADJUSTMENT TO ADAPT SATELLITE COMMUNICATIONS

EP4742558A2EP 4742558 A2EP4742558 A2EP 4742558A2EP-4742558-A2

Abstract

The described features generally relate to adjusting a native antenna pattern of a satellite to adapt communications via the satellite. For example, a communications satellite may include an antenna having a feed array assembly, a reflector, and a linear actuator coupled between the feed array assembly and the reflector. The feed array assembly may have a plurality of feeds for communicating signals associated with a communications service, and the reflector may be configured to reflect the signals transmitted between the feed array assembly and one or more target devices. The linear actuator may have an adjustable length, or otherwise provide an adjustable position between the feed array assembly and the reflector. By adjusting the position of the feed array assembly relative to the reflector, the communications satellite may provide a communications service according to a plurality of native antenna patterns.

Inventors

  • MENDELSOHN, AARON
  • RUNYON, DONALD

Assignees

  • ViaSat, Inc.

Dates

Publication Date
20260513
Application Date
20170410

Claims (20)

  1. A method for providing a communications service via a communications satellite (120) having an antenna assembly (121) with a plurality of antenna feed elements (128), the method comprising: transmitting, to the communications satellite (120), a first set of signals of the communications service for transmission according to a first native antenna pattern (220) of the plurality of antenna feed elements (128), the first native antenna pattern (220) comprising a composite of first native feed element patterns (210) of the plurality of antenna feed elements (128); transmitting, to the communications satellite (120), a command to change from the first native antenna pattern (220) of the plurality of antenna feed elements (128) to a second native antenna pattern (220) of the plurality of antenna feed elements (128), the second native antenna pattern (220) comprising a composite of second native feed element patterns (210) of the plurality of antenna feed elements (128), wherein a given antenna feed element (128) of the plurality of antenna feed elements (128) is associated with one of the first native feed element patterns (210) and one of the second native feed element patterns (210), and wherein the one of the second native feed element patterns (210) is different from the one of the first native feed element patterns (210); transmitting, to the communications satellite (120), a second set of signals of the communications service for transmission according to the second native antenna pattern (220) of the plurality of antenna feed elements (128), wherein transmitting the command to change from the first native antenna pattern (220) to the second native antenna pattern (220) comprises: commanding an actuator (124) of the communications satellite (120) to provide the change from the first native antenna pattern (220) to the second native antenna pattern (220), wherein commanding the actuator (124) to provide the change from the first native antenna pattern (220) to the second native antenna pattern (220) comprises: commanding a spatial adjustment between a reflector (122) of the antenna assembly (121) and a feed array assembly (127) of the antenna assembly (121) comprising the plurality of antenna feed elements (128), wherein the first native antenna pattern (220) is based at least in part on a first relative distance between the reflector (122) of the antenna assembly (121) and the feed array assembly (127) of the antenna assembly (121) comprising the plurality of antenna feed elements (128), and the second native antenna pattern (220) is based at least in part on a second relative distance between the reflector (122) and the feed array assembly (127), different from the first relative distance, wherein the first relative distance corresponds to a first defocused position of the feed array assembly (127) relative to the reflector (122) and the second relative distance corresponds to a second defocused position of the feed array assembly (127) relative to the reflector (122).
  2. The method of claim 1, wherein the actuator (124) is coupled between the reflector (122) of the antenna assembly (121) and the feed array assembly (127).
  3. The method of claim 1, wherein the command to change from the first native antenna pattern (220) to the second native antenna pattern (220) comprises: commanding a linear actuator (124) coupled between the reflector (122) and the feed array assembly (127) to change from a first length to a second length.
  4. The method of claim 3, wherein transmitting the command to change from the first native antenna pattern (220) to the second native antenna pattern (220) comprises: commanding a secondary actuator (2540) coupled between the feed array assembly (127) and the reflector (122) to provide the second native antenna pattern (220), the commanding of the secondary actuator (2540) causing a change in relative position between the feed array assembly (127) and the reflector (122) about an axis different from an axis of the linear actuator (124).
  5. The method of claim 1, wherein one or both of the first defocused position or the second defocused position is associated with one or more of the plurality of antenna feed elements (128) being located between the reflector (122) and a focal region (123) of the reflector (122).
  6. The method of claim 1, wherein transmitting the command to change from the first native antenna pattern (220) to the second native antenna pattern (220) comprises: commanding an indication of the second relative distance, a difference between the first relative distance and the second relative distance, a desired position of the reflector (122), a desired position of the feed array assembly (127), a length of a linear actuator (124), a parameter of the second native antenna pattern (220), or a lookup value associated with the second native antenna pattern (220), or a combination thereof.
  7. The method of any of claims 1 to 6, wherein transmitting the command is based at least in part on an orbital position of the communications satellite (120), or a change in an orbital position of the communications satellite (120), or a change in orbital path of the communications satellite (120), or a change in attitude of the communications satellite (120), or a combination thereof.
  8. The method of any of claims 1 to 7, further comprising: determining a traffic condition associated with the communications service, wherein transmitting the command is triggered based at least in part on the determined traffic condition.
  9. The method of any of claims 1 to 8, further comprising: determining a change in one or more access node terminals (130) employed to provide the communications service, wherein transmitting the command is triggered based at least in part on the determined change.
  10. The method of any of claims 1 to 9, wherein the first native antenna pattern (220) is associated with a first native antenna pattern coverage area (221), and the second native antenna pattern (220) is associated with a second native antenna pattern coverage area (221) that is different from the first native antenna pattern coverage area (221).
  11. The method of any of claims 1 to 10, wherein the first set of signals corresponds to a first service coverage area (410) of the communications satellite (120), and the second set of signals corresponds to a second service coverage area (410) of the communications satellite (120), the second service coverage area (410) at least partially overlapping the first service coverage area (410).
  12. The method of any of claims 1 to 11, wherein the first native antenna pattern (220) is associated with a first boresight direction of the antenna assembly (121), and the second native antenna pattern (220) is associated with a second boresight direction of the antenna assembly (121) that is different from the first boresight direction.
  13. The method of any of claims 1 to 12, wherein the first native antenna pattern (220) is associated with a first native feed element pattern beamwidth of the given antenna feed element (128), and the second native antenna pattern (220) is associated with a second native feed element pattern beamwidth of the given antenna feed element (128) that is different from the first native feed element pattern beamwidth.
  14. The method of any of claims 1 to 13, wherein the first native antenna pattern (220) is associated with a first amount of overlap of native feed element patterns (210) of two or more antenna feed elements (128) of the antenna assembly (121), and the second native antenna pattern (220) is associated with a second, different amount of overlap of the native feed element patterns (210) of the two or more antenna feed elements (128) of the antenna assembly (121).
  15. The method of any of claims 1 to 9, further comprising: transmitting a command to adjust an orbital characteristic of the communications satellite (120), wherein transmitting the second set of signals comprises transmitting signals according to the adjusted orbital characteristic.
  16. The method of any of claims 1 to9, wherein the communications satellite (120) is at a same geostationary orbital position while transmitting the first set of signals and while transmitting the second set of signals.
  17. The method of any of claims 1 to 9, wherein: the communications satellite (120) is at a first geostationary orbital position while transmitting the first set of signals; the commanding the communications satellite (120) to change from the first native antenna pattern (220) to the second native antenna pattern (220) comprises commanding the communications satellite (120) to move from the first geostationary orbital position to a second, different geostationary orbital position; and the communications satellite (120) is at the second geostationary orbital position while transmitting the second set of signals.
  18. The method of any of claims 1 to 17, wherein the communications satellite (120) comprises a second antenna assembly (121) with a second plurality of antenna feed elements (128), the method further comprising: transmitting, to the communications satellite (120), a command to change from a third native antenna pattern (220) of the plurality of antenna feed elements (128), the third native antenna pattern (220) comprising a composite of third native feed element patterns (210) of the second plurality of antenna feed elements (128) to a fourth native antenna pattern (220) of the second plurality of antenna feed elements (128), the fourth native antenna pattern (220) comprising a composite of fourth native feed element patterns (210) of the second plurality of antenna feed elements (128), wherein a given antenna feed element (128) of the second plurality of antenna feed elements (128) is associated with one of the third native feed element patterns (210) and one of the fourth native feed element patterns (210), and wherein the one of the fourth native feed element patterns (210) is different from the one of the third native feed element patterns (210).
  19. The method of any of claims 1 to 18, wherein the first beamforming configuration comprises applying a first beamforming weight set to a first plurality of feed element signals carried via the plurality of antenna feed elements (128), and the second beamforming configuration comprises applying a second beamforming weight set to a second plurality of feed element signals carried via the plurality of antenna feed elements (128), different from the first beamforming weight set.
  20. A satellite communications system configured to perform the method of any preceding claim.

Description

BACKGROUND Communications satellites typically include one or more antenna assemblies for communicating with various terrestrial target devices, which may include ground-based access node terminals or user terminals, any of which may be stationary (e.g., installed at a permanent installation site, moved from one fixed installation site to another, etc.) or mobile (e.g., installed at a vehicle, a boat, a plane, etc.). An antenna assembly of a communications satellite may be configured for transmitting downlink signals (e.g., forward link signals to user terminals, return link signals to access nodes) and/or receiving uplink signals (e.g., forward link signals from access nodes, return link signals from user terminals). The antenna assembly may be associated with a service coverage area within which devices may be provided a communications service via the antenna assembly. The satellite may be a geostationary satellite, in which case the satellite's orbit is synchronized with the rotation of the Earth, keeping the service coverage area essentially stationary with respect to the Earth. In other cases, the satellite is in an orbit about the Earth that causes the service coverage area to move over the surface of the Earth as the satellite traverses its orbital path. Some satellite communication systems employ "bent-pipe" satellites that relay signals among terminals located in the same antenna footprint (e.g., service coverage area), for example, the continental Unites States. In circumstances where transmit and receive coverage areas are overlapping, separate frequency bands and/or polarizations may be used for the uplink (to the satellite) and the downlink (from the satellite). The "bent-pipe" designation refers to the fact that the relayed signals are effectively retransmitted after the signals are received by the satellite, as if redirected through a bent pipe. The data in the relayed signals is not demodulated or remodulated as in a "regenerative" or processing satellite architecture. Rather, signal manipulation on the satellite in a bent-pipe architecture is generally limited to functions such as frequency translation, filtering, amplification, and the like. Other satellite communication systems were developed around satellites that employ innovations such as digital channelization and routing of signals, demodulation/routing/re-modulation of the data in the relayed signals, narrow antenna footprint spot beams to allow frequency reuse, and phased array antennas to allow dynamic placement of coverage areas. For example, satellites for Mobile Satellite Services (MSS) typically employ spot beam coverage areas with a greater degree of frequency reuse. Examples of satellites for MSS include the Inmarsat-4 satellites and the Thuraya satellites. These satellites typically feature a large number of narrow spot beams covering a large composite area and allow for flexible and configurable allocation of bandwidth. However, the total system bandwidth is low (such as a 34 MHz allocation at L-band), and service is generally categorized as "narrow band" (e.g., carrier bandwidths of hundreds of kHz), which allows the flexible and configurable bandwidth allocation to be accomplished using digital beamforming techniques. These satellites use a large reflector with an active feed array. The signals associated with each antenna feed element are digitized, and the beamforming and bandwidth flexibility are provided by a digital signal processor. The digital beamforming is performed on narrowband channels, allowing any narrowband channel on the feeder link to be placed at any frequency for any spot beam shape. The Wideband InterNetworking Engineering Test and Demonstration Satellite (WINDS) is an experimental Ka-band satellite system. The satellite implements both fixed spot beams using a fixed multi-beam antenna (MBA) and steerable beams using an active phased array antenna (APAA). The MBA serves fixed beams, and the communications link can be switched over time in a pattern consisting of combinations of receiving and transmitting beams. The APAA has been developed as a beam-hopping antenna with a potential service area that covers almost the entire visible region of earth from the satellite. The APAA can provision communications between arbitrary users using two independently steerable beams for each of the transmitting and receiving antennas. Beam steering is achieved by updating pointing directions via control of digital phase shifters in switching interval slots as short as 2 ms in Satellite Switched Time Division Multiple Access (SS-TDMA) mode, where the shortest beam dwell time corresponds to the slot time of the SS-TDMA system. Beam switching at high speed is supported for up to eight locations per beam. Switching patterns for both the MBA and APAA are uploaded from a network management center. Spaceway is a Ka-band satellite system that services 112 uplink beams and nearly 800 downlink beams over the United States. The