Coherent power combining via wavefront multiplexing on deep space spacecraft

• US 10,003,399 B2
• Filed: 06/11/2015
• Issued: 06/19/2018
• Est. Priority Date: 07/30/2009
• Status: Active Grant

• Current Assignee: Spatial Digital Systems Inc
• Original Assignee: Spatial Digital Systems Inc
• Inventors: Chang, Donald C. D.
• Primary Examiner(s): Renner, Brandon M
• Application Number:
  US14/736,292
• Publication Number:
  US 20150288442A1
• Time in Patent Office: 1,104 Days
• Field of Search: None
• CPC Class Codes: H04B 7/0413 MIMO systems
• 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 7/18523 Satellite systems for providing broadcast service to terrestrial stations, i.e. broadcast satellite service arrangements specially adapted for satellite broadcast receiving H04H40/90; picture transmission via satellite H04N1/00103; television transmission via satellite H04N7/20
• CPC Class Codes: H04B 7/2041 Spot beam multiple access
• CPC Class Codes: H04J 14/00 Optical multiplex systems
• CPC Class Codes: H04J 14/005 Optical Code Multiplex
• CPC Class Codes: H04J 14/08 Time-division multiplex systems
• CPC Class Codes: H04L 25/03006 Arrangements for removing intersymbol interference

Abstract

A communication system and method for a deep space spacecraft receiver to perform post-processing to dynamically combine received signal power coherently for pre-processed signal streams radiated non-coherently from a distributed, multiple element, Ka-band transmitting array via multiple concurrent propagation paths. Mutually orthogonal data and pilot signals travel though the multiple propagation paths. A pre-processor utilizing wavefront multiplexing restructures signal streams on the ground into multi-channel wavefrom structures along with injections of pilot signals for diagnostic and probing purposes. These restructured, or “wavefront multiplexed” (WFM) signals are transmitted through propagation channels to a receiver on the spacecraft, wherein adaptive equalization and wavefront de-multiplexing coherently separates the mixtures of received WFM signals. Transmitting power can be dynamically allocated for the multiple concurrent data streams, radiated to different spacecraft within the same field of view according to continuously changing demand by changing the relative input power ratios of the WFM signal mixtures.

Claims

1. A ground-based system for communicating with a spacecraft, comprising:

a demultiplexing device to provide N signals from a data stream, the demultiplexing device comprising;

a time-division demultiplexer to demultiplex the data stream into M signals, M being a positive integer greater than or equal to 1, and

a pilot signal generator to generate P pilot signals, P being a positive integer greater than or equal to 1;

a processor comprising N input ports and N output ports, N being a positive integer equal to P+M, receiving concurrently N signals at the N input ports, performing an N-to-N wavefront multiplexing transform on the N signals and outputting concurrently N wavefront multiplexed signals at the N output ports such that the N wavefront multiplexed signals are orthogonal to one another and each of the N wavefront multiplexed signals is a unique linear combination of the N signals;

a set of Q time division multiplexers coupled to the processor to generate Q sequences embedding the N wavefront multiplexed signals, each of the Q time division multiplexers being an R-to-1 multiplexer, Q and R being positive integers such that Q*R is greater than or equal to N; and

a set of Q subarrays coupled respectively to the set of Q time division multiplexers to process the N wavefront multiplexed signals embedded in the Q sequences and radiate respectively and concurrently the processed N wavefront multiplexed signals toward the spacecraft.

2. The ground-based system of claim 1 further comprising a set of Q encoders coupled respectively to the Q time division multiplexers, each of the Q encoders encoding a respective one of the N wavefront multiplexed signals embedded in one of the Q sequences with a unique code.

3. The ground-based system of claim 2, wherein the unique codes comprise orthogonal codes.

4. The ground-based system of claim 1, wherein the processor performs one of a Fast Fourier transform, a Hartley transform, a Hadamard transform, or a Walsh-Hadamard transform on the N signals.

5. The ground-based system of claim 1, wherein each of the Q subarrays comprises:

a frequency up-converter configured to frequency up-convert a respective one of the N wavefront multiplexed signals embedded in one of the Q sequences;

a power amplifier coupled to the frequency up-converter and configured to amplify the respective one of the N wavefront multiplexed signals; and

a radiator coupled to the power amplifier and configured to radiate the amplified respective one of the N wavefront multiplexed signals toward the spacecraft.

6. The ground-based system of claim 1, wherein each of the Q subarrays comprises:

a digital beam forming network receiving a respective one of the N wavefront multiplexed signals embedded in one of the Q sequences and outputting a plurality of beam signals;

a set of frequency up-converters coupled to the digital beam forming network and configured to frequency up-convert the beam signals;

a set of power amplifiers coupled to the frequency up-converters and configured to amplify the up-converted beam signals; and

a radiator coupled to the power amplifiers and configured to radiate the amplified up-converted beam signals toward the spacecraft.

7. The ground-based system of claim 6 further comprising optical interconnects which connect the processor to the Q subarrays.

8. A ground-based system for communicating with a spacecraft, comprising:

a set of Q time division demultiplexers to provide Q*R sequences embedding N signals transformed from a data stream and received from an antenna, each of the Q time division demultiplexers being a 1-to-R demultiplexer, Q and R being positive integers such that Q*R is greater than or equal to N, N being a positive integer greater than 1;

a processor comprising N input ports and N output ports, coupled to the Q time division demultiplexers at the N input ports and receiving concurrently N signals at the N input ports, performing an N-to-N wavefront demultiplexing transform on the N signals and outputting concurrently N wavefront demultiplexed signals at the N output ports such that the N wavefront demultiplexed signals are orthogonal to one another and each of the N wavefront demultiplexed signals is a unique linear combination of the N signals;

an M-to-1 multiplexer coupled to M of the N output ports of the processor

to recover the data stream, M being a positive integer smaller than or equal to N.

9. The ground-based system of claim 8 further comprising:

a redundancy remover coupled to the set of Q time division demultiplexers to remove redundant signals from the N signals when Q*R is greater than N.

10. The ground-based system of claim 8 further comprising a set of Q decoders coupled respectively to the Q time-division demultiplexers, each of the Q decoders decoding a respective one of the Q*R sequences with a unique code.

11. The ground-based system of claim 10, wherein the unique codes comprise orthogonal codes.

12. The ground-based system of claim 8, wherein the processor performs an inverse transform of one of a Fast Fourier transform, a Hartley transform, a Hadamard transform, or a Walsh-Hadamard transform on the N signals.