System and method for distributed wireless communications

• US 10,200,109 B2
• Filed: 04/29/2016
• Issued: 02/05/2019
• Est. Priority Date: 04/29/2016
• Status: Active Grant

• Current Assignee: The Boeing Co.
• Original Assignee: The Boeing Co.
• Inventors: Feria, Ying J., Whelan, David A., Busche, Greg
• Primary Examiner(s): Yuen, Kan
• Application Number:
  US15/142,267
• Publication Number:
  US 20170317742A1
• Time in Patent Office: 1,012 Days
• CPC Class Codes: H04B 7/18504 Aircraft used as relay or high altitude atmospheric platform
• CPC Class Codes: H04L 5/0023 Time-frequency-space
• CPC Class Codes: H04W 16/28 using beam steering

Abstract

A communications system includes radio frequency equipment to generate a forward link configured for wireless transmissions of a base-to-user data stream from a plurality of airborne communications relay platforms to at least one user terminal, wherein the forward link includes a plurality of relay-to-user links, each one of the plurality of relay-to-user links includes a relay-to-user radio frequency signal encoded with a different base-to-user data sub-stream.

Claims

1. A communications system comprising:

radio frequency equipment comprising;

a multiple-input multiple-output orthogonal frequency division multiplexing system operable to wirelessly communicate radio frequency signals encoded with a base-to-user data stream from a base station to a user terminal; and

a signal coordinator operable to control a phase and an amplitude of said radio frequency signals transmitted by said multiple-input multiple-output orthogonal frequency division multiplexing system;

a first airborne communications relay platform configured to receive a first base-to-relay radio frequency signal encoded with a first base-to-user data sub-stream of said base-to-user data stream from said base station and transmit a first relay-to-user radio frequency signal encoded with said first base-to-user data sub-stream of said base-to-user data stream to said user terminal; and

a second airborne communications relay platform configured to receive a second base-to-relay radio frequency signal encoded with a second base-to-user data sub-stream of said base-to-user data stream from said base station and transmit a second relay-to-user radio frequency signal encoded with said second base-to-user data sub-stream of said base-to-user data stream to said user terminal; and

wherein said phase and said amplitude of said first base-to-relay radio frequency signal and said second base-to-relay radio frequency signal are selected to pre-compensate for time delay, phase alignment, and spatial positioning of said first base-to-relay radio frequency signal and said second base-to-relay radio frequency signal so that said first base-to-relay radio frequency signal and said second base-to-relay radio frequency signal are spatially aligned at said user terminal and said first base-to-user data sub-stream and said second base-to-user data sub-stream are combined as received by said user terminal.

2. The system of claim 1 wherein said radio frequency equipment is distributed among base station-radio frequency equipment on said base station, relay platform-radio frequency equipment onboard said first airborne communications relay platform and said second airborne communications relay platform, and user terminal-radio frequency equipment on said user terminal.

3. The system of claim 2 wherein:

said relay platform-radio frequency equipment comprises a multiple-input multiple-output orthogonal frequency division multiplexing transmitter to transmit said first relay-to-user radio frequency signal and said second relay-to-user radio frequency signal to said user terminal; and

said user terminal-radio frequency equipment comprises multiple-input multiple-output orthogonal frequency division multiplexing receiver to receive said first relay-to-user radio frequency signal from said first airborne communications relay platform and said second relay-to-user radio frequency signal from said second airborne communications relay platform.

4. The system of claim 1 wherein said first base-to-relay radio frequency signal and said second base-to-relay radio frequency signal have different frequencies.

5. The system of claim 1 wherein said first relay-to-user radio frequency signal and said second relay-to-user radio frequency signal at least partially overlap forming a common service area, and wherein said user terminal is located within said common service area.

6. The system of claim 1 wherein said first relay-to-user radio frequency signal and said second relay-to-user radio frequency signal have different frequencies.

7. The system of claim 1 wherein each one of said first airborne communications relay platform and said second airborne communications relay platform comprise a high altitude aerial platform.

8. The system of claim 1 wherein each one of said first airborne communications relay platform and said second airborne communications relay platform comprise an unmanned areal vehicle traveling along a predetermined flight path at an altitude of between approximately 12 kilometers and approximately 55 kilometers.

9. The system of claim 8 wherein each one of said first airborne communications relay platform and said second airborne communications relay platform travels along a predetermined flight path at an altitude of between approximately 12 kilometers and approximately 55 kilometers.

10. The system of claim 1 wherein said signal coordinator is operable to select said phase and said amplitude of said radio frequency signals transmitted by said multiple-input multiple-output orthogonal frequency division multiplexing system based on a path of each one of said radio frequency signals from a corresponding one of said first airborne communications relay platform and said second airborne communications relay platform to said user terminal to pre-compensate for said time delay, said phase alignment, and said spatial positioning of said first base-to-relay radio frequency signal and said second base-to-relay radio frequency signal.

11. A communications system comprising:

a base station comprising base station-radio frequency equipment configured to transmit a first base-to-relay radio frequency signal encoded with a first base-to-user data sub-stream of a base-to-user data stream and a second base-to-relay radio frequency signal encoded with a second base-to-user data sub-stream of said base-to-user data stream;

a first airborne communications relay platform comprising first relay platform-radio frequency equipment, comprising;

a first relay platform-multiple-input multiple-output orthogonal frequency division multiplexing receiver configured to receive said first base-to-relay radio frequency signal from said base station; and

a first relay platform-multiple-input multiple-output orthogonal frequency division multiplexing transmitter configured to transmit a first relay-to-user radio frequency signal encoded with said first base-to-user data sub-stream of said base-to-user data stream to a user terminal; and

a second airborne communications relay platform relay platform-radio frequency equipment, comprising;

a second relay platform-multiple-input multiple-output orthogonal frequency division multiplexing receiver configured to receive said second base-to-relay radio frequency signal from said base station; and

a second relay platform-multiple-input multiple-output orthogonal frequency division multiplexing transmitter configured to transmit a second relay-to-user radio frequency signal encoded with said second base-to-user data sub-stream of said base-to-user data stream to said user terminal; and

a signal coordinator operable to control a first phase and a first amplitude of said first relay-to-user radio frequency signal, transmitted by said first relay platform-multiple-input multiple-output orthogonal frequency division multiplexing transmitter and to control a second phase and a second amplitude of said second relay-to-user radio frequency signal, transmitted by said second relay platform-multiple-input multiple-output orthogonal frequency division multiplexing transmitter;

wherein said first phase and said first amplitude said first base-to-relay radio frequency signal and said second phase and said second amplitude of said second base-to-relay radio frequency signal are selected to pre-compensate for time delay, phase alignment, and spatial positioning of said first base-to-relay radio frequency signal and said second base-to-relay radio frequency signal so that said first base-to-relay radio frequency signal and said second base-to-relay radio frequency signal are spatially aligned at said user terminal and said first base-to-user data sub-stream and said second base-to-user data sub-stream are combined as received by said user terminal.

12. The system of claim 11 further comprising a beamformer to shape and direct said first relay-to-user radio frequency signal into a first radio frequency beam and said second relay-to-user radio frequency signal into a second radio frequency beam, wherein said first radio frequency beam and said second radio frequency beam at least partially overlap covering a common service area, and wherein said user terminal is located within said common service area.

13. The system of claim 12 wherein said first relay-to-user radio frequency signal and said second relay-to-user radio frequency signal have different frequencies.

14. The system of claim 11 further comprising said user terminal comprising user terminal-radio frequency equipment, comprising a user terminal-multiple-input multiple-output orthogonal frequency division multiplexing receiver configured to receive said first relay-to-user radio frequency signal from said first airborne communications relay platform and to receive said second relay-to-user radio frequency signal from said second airborne communications relay platform.

15. The system of claim 14 wherein said base station-radio frequency equipment comprises a base-station multiple-input multiple-output orthogonal frequency division multiplexing transmitter configured to transmit said first base-to-relay radio frequency signal to said first airborne communications relay platform and to transmit said second base-to-relay radio frequency signal to said second airborne communications relay platform.

16. The system of claim 11 wherein each one of said first airborne communications relay platform and said second airborne communications relay platform comprise a high altitude aerial platform.

17. The system of claim 11 further comprising a second base station configured to transmit said first base-to-relay radio frequency signal encoded with said first base-to-user data sub-stream of said base-to-user data stream and said second base-to-relay radio frequency signal encoded with said second base-to-user data sub-stream of said base-to-user data stream;

and wherein;

said first base station transmits one of said first base-to-relay radio frequency signal to said first airborne communications relay platform or said second base-to-relay radio frequency signal to said second airborne communications relay platform; and

said second base station transmits an alternate one of said first base-to-relay radio frequency signal to said first airborne communications relay platform or said second base-to-relay radio frequency signal to said second airborne communications relay platform.

18. A method comprising:

transmitting, by a base station, a first base-to-relay radio frequency signal encoded with a first base-to-user data sub-stream of said base-to-user data stream and a second base-to-relay radio frequency signal encoded with a second base-to-user data sub-stream of said base-to-user data stream;

receiving, by a first airborne communications relay platform in communication with said base station, said first base-to-relay radio frequency signal;

receiving, by a second airborne communications relay platform in communication with said base station, said second base-to-relay radio frequency signal;

transmitting, from said first airborne communications relay platform, a first relay-to-user radio frequency signal encoded with said first base-to-user data sub-stream of said base-to-user data stream;

transmitting, from said second airborne communications relay platform, a second relay-to-user radio frequency signal encoded with said second base-to-user data sub-stream of said base-to-user data stream;

selecting a first phase and a first amplitude for said first relay-to-user radio frequency signal and a second phase and a second amplitude for said relay-to-user radio frequency signal to pre-compensate for time delay, phase alignment, and spatial positioning of said first base-to-relay radio frequency signal and said second base-to-relay radio frequency signal;

spatially aligning said first relay-to-user radio frequency signal and said second relay-to-user radio frequency signal in space at a user terminal in communication with said first airborne communications relay platform and said second airborne communications relay platform; and

combining said first base-to-user data sub-stream and said second base-to-user data sub-stream as received by said user terminal.

19. The method of claim 18 further comprising beamforming said first relay-to-user radio frequency signal into a first radio frequency beam and said second relay-to-user radio frequency signal into a second radio frequency beam, wherein said first radio frequency beam and said second radio frequency beam at least partially overlap covering a common service area, and wherein said user terminal is located within said common service area.

20. The method of claim 19 wherein said first relay-to-user radio frequency signal and said second relay-to-user radio frequency signal have different frequencies.