Array processing for satellite communications

• US 9,473,234 B2
• Filed: 03/06/2014
• Issued: 10/18/2016
• Est. Priority Date: 03/06/2014
• Status: Active Grant

• Current Assignee: Northrop Grumman Systems Corporation (Northrop Grumman Corporation)
• Original Assignee: Northrop Grumman Systems Corporation (Northrop Grumman Corporation)
• Inventors: Shreve, Gregory Alan, Schatzman, James Carl
• Primary Examiner(s): Zhu, Alvin
• Application Number:
  US14/199,047
• Publication Number:
  US 20150304019A1
• Time in Patent Office: 957 Days
• US Class Current: 1/1
• CPC Class Codes: H04B 17/309 Measuring or estimating channel quality parameters
• CPC Class Codes: H04B 7/0413 MIMO systems
• CPC Class Codes: H04B 7/185 Space-based or airborne stations; Stations for satellite systemsH04B7/204 takes precedence
• CPC Class Codes: H04B 7/18517 Transmission equipment in earth stations

Abstract

A satellite communications system includes a plurality of satellites that generate communications data over a plurality of channels. A plurality of antennas receives the communications data over the plurality of channels generated by the plurality of satellites. Each of the antennas receives a separate signal from each of the plurality of satellites over the channels. A converter digitizes each of the separate signals from each of the plurality of satellites received at the plurality of antennas. A processor forms separate digital beams from each of the separate signals digitized by the converter.

Claims

1. A satellite communications system, comprising:

a plurality of satellites that generate communications data over a plurality of channels;

a plurality of antennas that receive the communications data over the plurality of channels generated by the plurality of satellites, wherein each of the antennas receives a separate signal from each of the plurality of satellites over the channels;

a converter to digitize each of the separate signals from each of the plurality of satellites received at the plurality of antennas; and

a processor that forms separate digital beams from each of the separate signals digitized by the converter, wherein the processor determines a collective signal for a selected satellite by summing each of the separate digital beams associated with each of the plurality of satellites, and utilizes the separate digital beams from the non-selected satellites from the plurality of satellites to filter cross-channel interference from the collective signal.

2. The satellite communications system of claim 1, wherein the plurality of antennas includes at least one of a ground based receiving antenna and a ground based transmitter/receiver antenna.

3. The satellite communications system of claim 1, further comprising N×

M channels that are formed between the plurality of satellites and the plurality of antennas,

wherein N is a positive integer associated with the number of satellites and M is a positive integer associated with the number of antennas.

4. The satellite communications system of claim 3, further comprising a matrix that is formatted by the processor, wherein the matrix includes N rows for each of the plurality of satellites having M columns associated with each of the antennas.

5. The satellite communications system of claim 4, wherein processor employs one of the N rows of the matrix to determine the collective signal for the selected satellite by coherently summing each of the separate beams associated with each of the plurality of satellites and the processor employs N−

1 rows of the matrix for the separate beams from the non-selected satellites from the plurality of satellites to filter cross-channel interference from the collective signal.

6. The satellite communications system of claim 5, wherein timing and phase information is received from the plurality of satellites and employed by the processor to filter the cross-channel interference from the collective signal via the matrix.

7. The satellite communications system of claim 6, wherein the processor formats M columns of the matrix to include a term for each of the M antennas, wherein each term in each column of the matrix includes the magnitude and phase information for each of the plurality of satellites multiplied by the separate signal for each of the M antennas.

8. The satellite communications system of claim 7, wherein the processor determines the collective signal by coherently summing one row of the matrix and the processor employs the other N−

1 rows of the matrix as a cancellation sum to subtract cross-channel interference to the collective signal attributed to the non-selected satellites of the plurality of satellites.

9. The satellite communications system of claim 8, further comprising a plurality of matrixes that are formatted by the processor to determine a separate collective signal for each satellite from the plurality of satellites and to filter cross-channel interference from each of the plurality of satellites from the separate collective signal.

10. The satellite communications system of claim 1, wherein the converter is an analog-to-digital (A/D) converter that operates in the ground stations, is a separate A/D converter that digitizes data received from each of the ground based antennas, or is an internal A/D of the processor that digitizes data received from each of the plurality of antennas.

11. The satellite communications system of claim 1, wherein the communications data is transferred over the channels between the plurality of satellites and the plurality of antennas according to a multiple input and multiple output protocol (MIMO).

12. A satellite communications system, comprising:

a plurality of satellites that exchange coordination data and mission data over cross-links between each of the plurality of satellites to generate communications data over a plurality of channels;

a plurality of antennas that receive the communications data over the plurality of channels generated by the plurality of satellites, wherein each of the antennas receives a composite signal from each of the plurality of satellites over the channels;

a converter to digitize each of the composite signals from the plurality of satellites received at the plurality of antennas; and

a processor that forms composite beams from the composite signals digitized by the converter, wherein the processor analyzes the composite beams with respect to the coordination data to determine the mission data for a selected satellite from the plurality of satellites.

13. The satellite communications system of claim 12, wherein the plurality of groundbased antennas include at least one of a ground based receiving antenna and a ground based transmitter/receiver antenna.

14. The satellite communications system of claim 12, wherein the coordination data includes position data and velocity data for each of the plurality of satellites.

15. The satellite communications system of claim 14, wherein the position data and the velocity data is determined from a predictive model or determined by instruments on each of the plurality of satellites.

16. The satellite communications system of claim 12, wherein a given satellite of the plurality of satellites utilizes the coordination data to perform a data time-shift with respect to data transmissions from each of the other satellites of the plurality of satellites to maximize reception of data generated by the given satellite at a selected antenna from the plurality of antennas.

17. The satellite communications system of claim 12, wherein each of the plurality of satellites form a composite beam for transmitting the communications data over the plurality of channels.

18. The satellite communications system of claim 12, wherein the communications data is transferred over the channels between the plurality of satellites and the plurality of antennas according to a multiple input and multiple output protocol (MIMO).

19. The satellite communications system of claim 12, further comprising a channel monitor to determine the quality of a selected channel between one of the plurality of satellites and one of the antennas.

20. The satellite communications system of claim 19, wherein the quality of the selected channel is based on a bit error rate (BER).

21. The satellite communications system of claim 19, further comprising a channel compensation command that communicates a data transfer rate increase or decrease to at least one of the satellites of the plurality of satellites based on the determined quality of the selected channel.

22. A method for satellite communications, comprising:

receiving, by a processor, data from each member of a satellite swarm to each member of a ground-based antenna array;

forming, by the processor, a separate beam for each channel created between the satellite swarm and the ground-based antenna array;

determining, by the processor, a collective signal for a selected satellite by coherently summing each of the separate beams associated with each channel; and

filtering, by the processor, cross-channel interference from the collective signal by subtracting an interference contribution associated with the separate beams of the non-selected satellites from the collective signal.

23. The method of claim 22, further comprising forming a matrix, by the processor, wherein the matrix includes N rows for each member of the satellite swarm having M columns associated with each member of the ground-based antenna array.

24. The method of claim 23, further comprising employing, by the processor, one of the N rows of the matrix to determine the collective signal for the selected satellite by coherently summing each of the composite beams associated with each member of the satellite swarm and employing N−

1 rows of the matrix for the composite beams from the non-selected satellites from the satellite swarm to filter cross-channel interference from the collective signal.

25. The method of claim 24, further comprising receiving, by the processor, timing and phase information from the satellite swarm and filtering the cross-channel interference from the collective signal via the matrix.

26. The method of claim 25, further comprising formatting, by the processor, M columns of the matrix to include a term for each member of the ground-based antenna array,

wherein each term in each column of the matrix includes the phase information for each member of the satellite swarm multiplied by the composite signal for each member of the ground-based antenna array.

27. The method of claim 26, further comprising determining, by the processor, the collective signal by coherently summing one row of the matrix and employing the other N−

1 rows of the matrix as a cancellation sum to subtract cross-channel interference to the collective signal attributed to the non-selected satellites of the satellite swarm.

28. A method for satellite communications, comprising:

receiving, by a processor, data from each member of a satellite swarm to each member of a ground-based antenna array, wherein the data includes coordination data and mission data that is shared between each member of the satellite swarm, wherein satellites of the satellite swarm exchange the coordination data and the mission data over cross-links between each other to generate communications data exchanged over a plurality of channels, wherein antennas of the ground-based antenna array receive the communications data generated by the satellites over the plurality of channels, wherein each of the antennas receives a composite signal from each of the satellites over the plurality of channels such that composite signals received at the antennas are digitized by a converter;

forming, by the processor, a composite beam for each channel created between the satellite swarm and the ground-based antenna array, the composite beam being formed from the composite signals digitized by the converter; and

analyzing, by the processor, the composite beams for each channel with respect to the coordination data to determine the mission data for a selected satellite from the plurality of satellites.

29. The method of claim 28, wherein the coordination data includes position data and velocity data for each of the plurality of satellites.

30. The method of claim 29, further comprising determining, by the processor, the position data and the velocity data from a predictive model or by instrumenting each member of the satellite swarm.

31. The method of claim 28, further comprising utilizing, by the processor, the coordination data to perform a data time-shift with respect to data transmissions from each of the other members of the satellite swarm to maximize reception of data generated by a given satellite at a selected antenna from the ground-based antenna array.

32. The method of claim 28, further comprising monitoring, by the processor, to determine the quality of a selected channel between one of the members of the satellite swarm and one of members of the ground-based antenna array.

33. The method of claim 32, wherein the quality of the selected channel is based on a bit error rate (BER).

34. The method of claim 32, further comprising communicating, by the processor, a data transfer rate increase or decrease to at least one member of the satellite swarm based on the determined quality of the selected channel.