Interference mitigation for a satellite network

• US 10,149,200 B2
• Filed: 06/07/2017
• Issued: 12/04/2018
• Est. Priority Date: 06/07/2016
• Status: Active Grant

• Current Assignee: Iridium Satellite Llc (Iridium Communications, Incorporated)
• Original Assignee: Iridium Satellite Llc (Iridium Communications, Incorporated)
• Inventors: Tatum, Patrick
• Primary Examiner(s): Trinh, Tan H
• Application Number:
  US15/616,020
• Publication Number:
  US 20170353871A1
• Time in Patent Office: 545 Days
• Field of Search: 455 121, 455 132, 455427, 455 133, 455 9, 455522, 4555757, 4555621, 455429, 455430, 455 111, 455447
• CPC Class Codes: H04B 15/00 Suppression or limitation of noise or interference by means associated with receiver H04B1/10
• CPC Class Codes: H04B 7/18513 Transmission in a satellite or space-based system
• CPC Class Codes: H04B 7/195 Non-synchronous stations
• CPC Class Codes: H04W 16/28 using beam steering
• CPC Class Codes: H04W 28/08 Load balancing or load distribution transferring a connection for handling the traffic H04W36/22; wireless traffic scheduling H04W72/12
• CPC Class Codes: H04W 84/06 Airborne or Satellite Networks space-based or airborne stations H04B7/185

Abstract

In one implementation, interference generated by a constellation of satellites is mitigated. Each satellite is configured to provide multiple beams that define a coverage footprint. Anticipated positions are determined for satellites. Based on the anticipated positions, a determination is made that, during a defined period of time, portions of a coverage footprint for a first satellite will be covered by coverage footprints for other satellites. Based on this, a beam assignment for the first satellite is defined in which a first subset of beams configured to provide coverage of a first portion of the first coverage footprint are inactive, and a beam assignment for a second satellite is defined in which a second subset of beams are active, where the second subset of beams provide coverage within the first portion of the first coverage footprint.

Claims

1. A method for mitigating out-of-band interference generated by one or more communications satellites within a constellation of low-Earth orbit communications satellites, the method comprising:

determining, using one or more processors, anticipated positions of each of a plurality of satellites within the constellation, wherein each satellite has an antenna system configured to provide multiple beams that collectively define a coverage footprint for the satellite with individual ones of the beams configured to provide coverage of respective portions of the coverage footprint;

determining, using the one or more processors and based on the determined anticipated positions of each of the satellites, that, during a defined period of time, portions of a first coverage footprint for a first satellite from among the plurality of satellites also will be covered by coverage footprints for other satellites from among the plurality of satellites;

defining, using the one or more processors and based on having determined that portions of the first coverage footprint for the first satellite also will be covered by coverage footprints for the other satellites during the defined period of time;

a beam assignment for the first satellite during the defined period of time in which a first subset of beams of the first satellite configured to provide coverage of a first portion of the first coverage footprint are inactive, and

a beam assignment for a second satellite from among the plurality of satellites during the defined period of time in which a second subset of beams of the second satellite are active, the second subset of beams of the second satellite providing coverage within the first portion of the first coverage footprint during the defined period of time; and

causing, using the one or more processors, the beam assignment for the first satellite to be transmitted to the first satellite and the beam assignment for the second satellite to be transmitted to the second satellite.

2. The method of claim 1, wherein the beam assignment for the first satellite comprises an instruction to de-activate a first beam provided by the first satellite during the defined period of time, wherein the first beam was active immediately prior to the defined period of time.

3. The method of claim 1, wherein:

the constellation of low-Earth orbit communications satellites comprises a constellation of low-Earth orbit communications satellites in near-polar orbits;

determining anticipated positions of each of a plurality of satellites within the constellation includes determining that the coverage footprint for the first satellite covers a first region that is above a predefined latitude;

determining, that, during the defined period of time, portions of the first coverage footprint for the first satellite also will be covered by coverage footprints for other satellites includes determining, as a consequence of having determined that, during the defined period of time, the coverage footprint for the first satellite covers a region above a predefined latitude, that, during the defined period of time;

the second subset of beams of the second satellite are configured to provide coverage within the first portion of the first coverage footprint, and

the coverage footprint for the second satellite covers a second region that is at a higher latitude than the first region covered by the first satellite; and

defining the beam assignment for the first satellite during the defined period of time in which the first subset of beams of the first satellite are inactive and defining the beam assignment for the second satellite during the defined period in which the second subset of beams of the second satellite are active includes defining the beam assignment for the first satellite during the defined period of time in which the first subset of beams of the first satellite are inactive and defining the beam assignment for the second satellite during the defined period in which the second subset of beams of the second satellite are active as a consequence of having determined that the coverage footprint for the second satellite covers a second region that is at a higher latitude than the first region covered by the first satellite.

4. The method of claim 1, wherein:

determining that, during the defined period of time, portions of a first coverage footprint for a first satellite from among the plurality of satellites also will be covered by coverage footprints for other satellites from among the plurality of satellites further comprises determining that, during the defined period of time, an area within the first coverage footprint for the first satellite is sensitive to out-of-band interference; and

defining the beam assignment for the first satellite and the beam assignment for the second satellite based on having determined that portions of the first coverage footprint for the first satellite also will be covered by coverage footprints for other satellites during the defined period of time comprises defining the beam assignment for the first satellite and the beam assignment for the second satellite based on having determined that portions of the first coverage footprint for the first satellite also will be covered by coverage footprints for other satellites during the defined period and that, during the defined period of time, an area within the first coverage footprint for the first satellite is sensitive to out-of-band interference.

5. The method of claim 4, wherein the beam assignment for the second satellite enables the second satellite to service a communication session with a terminal located within the first portion of the first coverage footprint for the first satellite.

6. The method of claim 5, wherein the terminal is configured to establish a communication session with whichever one of the satellites within the constellation of satellites from which signals received by the terminal are strongest, and wherein signals received by the terminal would be strongest from the first satellite if the first subset of beams were not inactive.

7. The method of claim 1, wherein the first satellite and second satellite each comprise:

an antenna array configured to generate the multiple beams; and

a controller configured to activate and de-activate individual ones of the multiple beams responsive to instructions.

8. The method of claim 1, wherein:

defining the beam assignment for the first satellite during the period of time includes storing the beam assignment for the first satellite during the period of time in a first beam laydown table that defines beam assignments for the first satellite during multiple periods of time;

defining the beam assignment for the second satellite during the period of time includes storing the beam assignment for the second satellite during the period of time in a second beam laydown table that defines beam assignments for the second satellite during multiple periods of time;

causing the beam assignment for the first satellite to be transmitted to the first satellite and the beam assignment for the second satellite to be transmitted to the second satellite includes causing the first beam laydown table to be transmitted to the first satellite and the second beam laydown table to be transmitted to the second satellite.

9. The method of claim 8, wherein the first beam laydown table defines the beam assignments for the first satellite during multiple periods of time by defining whether individual beams are active during each period of time, and wherein the second beam laydown table defines the beam assignments for the second satellite during multiple periods of time by defining whether individual beams are active during each period of time.

10. A system for managing communications satellites within a constellation of low-Earth orbit communications satellites to mitigate out-of-band interference generated by one or more of the satellites, the system comprising:

one or more processors; and

a memory coupled to the processors comprising instructions executable by the processors, the processors operable when executing the instructions to;

determine anticipated positions of each of a plurality of satellites within the constellation, wherein each satellite has an antenna system configured to provide multiple beams that collectively define a coverage footprint for the satellite with individual ones of the beams configured to provide coverage of respective portions of the coverage footprint;

determine, based on the determined anticipated positions of each of the satellites, that, during a defined period of time, portions of a first coverage footprint for a first satellite from among the plurality of satellites also will be covered by coverage footprints for other satellites from among the plurality of satellites;

define, based on having determined that portions of the first coverage footprint for the first satellite also will be covered by coverage footprints for the other satellites during the defined period of time;

a beam assignment for the first satellite during the defined period of time in which a first subset of beams of the first satellite configured to provide coverage of a first portion of the first coverage footprint are inactive, and

a beam assignment for a second satellite from among the plurality of satellites during the defined period of time in which a second subset of beams of the second satellite are active, the second subset of beams of the second satellite providing coverage within the first portion of the first coverage footprint during the defined period of time; and

cause the beam assignment for the first satellite to be transmitted to the first satellite and the beam assignment for the second satellite to be transmitted to the second satellite.

11. The system of claim 10, wherein the beam assignment for the first satellite comprises an instruction to de-activate a first beam provided by the first satellite during the defined period of time, wherein the first beam was active immediately prior to the defined period of time.

12. The system of claim 10, wherein:

the constellation of low-Earth orbit communications satellites comprises a constellation of low-Earth orbit communications satellites in near-polar orbits; and

the processors operable to determine anticipated positions of each of a plurality of satellites within the constellation comprise processors operable to determine that the coverage footprint for the first satellite covers a first region that is above a predefined latitude;

the processors operable to determine that, during the defined period of time, portions of the first coverage footprint for the first satellite also will be covered by coverage footprints for other satellites comprise processors operable to determine, as a consequence of having determined that, during the defined period of time, the coverage footprint for the first satellite covers a region above a predefined latitude, that, during the defined period of time;

the second subset of beams of the second satellite are configured to provide coverage within the first portion of the first coverage footprint, and

the coverage footprint for the second satellite covers a second region that is at a higher latitude than the first region covered by the first satellite;

the processors operable to define the beam assignment for the first satellite during the defined period of time in which the first subset of beams of the first satellite are inactive and define the beam assignment for the second satellite during the defined period of time in which the second subset of beams of the second satellite are active comprise processors operable to define the beam assignment for the first satellite during the defined period of time in which the first subset of beams of the first satellite are inactive and define the beam assignment for the second satellite during the defined period of time in which the second subset of beams of the second satellite are active as a consequence of having determined that the coverage footprint for the second satellite covers a second region that is at a higher latitude than the first region covered by the first satellite.

13. The system of claim 10, wherein:

the processors operable to determine that, during the defined period of time, portions of a first coverage footprint for a first satellite from among the plurality of satellites also will be covered by coverage footprints for other satellites from among the plurality of satellites comprise processors operable to determine that, during the defined period of time, an area within the first coverage footprint for the first satellite is sensitive to out-of-band interference; and

the processors operable to define the beam assignment for the first satellite and the beam assignment for the second satellite based on having determined that portions of the first coverage footprint for the first satellite also will be covered by coverage footprints for other satellites during the defined period of time comprise processors operable to define the beam assignment for the first satellite and the beam assignment for the second satellite based on having determined that portions of the first coverage footprint for the first satellite also will be covered by coverage footprints for other satellites during the defined period of time and that, during the defined period of time, an area within the first coverage footprint for the first satellite is sensitive to out-of-band interference.

14. The system of claim 10, wherein the beam assignment for the second satellite enables the second satellite to service a communication session with a terminal located within the first portion of the first coverage footprint for the first satellite.

15. The system of claim 14, wherein the terminal is configured to establish a communication session with whichever one of the satellites within the constellation of satellites from which signals received by the terminal are strongest, and wherein signals received by the terminal would be strongest from the first satellite if the first subset of beams were not inactive.