Permission-based multiple access communications systems

• US 8,428,104 B2
• Filed: 07/01/2009
• Issued: 04/23/2013
• Est. Priority Date: 07/01/2009
• Status: Active Grant

• Current Assignee: Harris Corporation (L3Harris Technologies, Inc.)
• Original Assignee: Harris Corporation (L3Harris Technologies, Inc.)
• Inventors: Michaels, Alan J., Chester, David B.
• Primary Examiner(s): FILE, ERIN M
• Application Number:
  US12/496,170
• Publication Number:
  US 20110002463A1
• Time in Patent Office: 1,392 Days
• Field of Search: 375/141
• US Class Current: 375/141
• CPC Class Codes: H04K 1/02 by adding a second signal to make the desired signal unintelligible
• CPC Class Codes: H04L 2209/12 Details relating to cryptographic hardware or logic circuitry
• CPC Class Codes: H04L 2209/20 Manipulating the length of blocks of bits, e.g. padding or block truncation
• CPC Class Codes: H04L 2209/80 Wireless
• CPC Class Codes: H04L 27/001 using chaotic signals for secret or secure communication H04L9/001
• CPC Class Codes: H04L 9/001 using chaotic signals
• CPC Class Codes: H04L 9/0662 with particular pseudorandom sequence generator
• CPC Class Codes: H04L 9/12 Transmitting and receiving encryption devices synchronised or initially set up in a particular manner

Abstract

Systems (100) and methods (400) for selectively controlling access to multiple data streams which are communicated using a shared frequency spectrum and shared spreading codes. The methods involve generating a first product signal (FPS) by spreading first symbols of a first amplitude modulated (AM) signal using a first spreading code (SC). The methods also involve generating a second product signal (SPS) by spreading second symbols of a complimentary AM signal using a second SC. The FPS (124) and SPS 126 are combined to form a protected data communication signal (PDCS) including first data recoverable by a receiver (106). A global data communication signal (GDCS) is combined with PDCS (128) to form an output signal (140) having a spread spectrum format. The GDCS is generated using a digital modulation process and includes second data recoverable by a plurality of receivers (106, 108).

Claims

1. A method for selectively controlling access to multiple data streams which are communicated using a shared frequency spectrum and shared spreading codes, comprising:

generating a first product signal by spreading first symbols of a first amplitude modulated signal using a first spreading code;

generating a second product signal by spreading second symbols of a complimentary amplitude modulated signal using a second spreading code;

combining said first and second product signals to form a protected data communication signal including first data recoverable by at least one receiver of a plurality of receivers; and

combining a global data communication signal and said protected data communication signal to form an output signal having a spread spectrum format;

wherein said global data communication signal is generated using a digital modulation process and includes second data recoverable by all of said plurality of receivers.

2. The method according to claim 1, wherein said first and second spreading codes include pseudo-random number sequences.

3. The method according to claim 1, wherein said first and second spreading codes include digitally generated chaotic sequences.

4. The method according to claim 1, wherein said second spreading code is orthogonal or statistically orthogonal to said first spreading code.

5. The method according to claim 1, wherein said digital modulation process includes a phase modulation process.

6. The method according to claim 1, wherein said first and second product signals are additively combined to produce a constant power envelope in said protected data communication signal.

7. The method according to claim 1, further comprising recovering said global data communication signal at a first receiver of said plurality of receivers by de-spreading said output signal using a sum of a third spreading code and a fourth spreading code which are respectively identical to said first spreading code and said second spreading code.

8. The method according to claim 7, further comprising synchronizing in time said first and third spreading codes, and said second and fourth spreading codes.

9. The method according to claim 7, further comprising preventing said first receiver from independently recovering the third spreading code or the fourth spreading code.

10. The method according to claim 1, further comprising recovering said first product signal at a first receiver of said plurality of receivers by de-spreading said output using a third spreading code that is identical to said first spreading code.

11. A communication system configured for selectively controlling access to multiple data streams which are communicated using a shared frequency spectrum and shared spreading codes, comprising:

a first discrete time amplitude modulator generating a first product signal by spreading first symbols of a first amplitude modulated signal using a first spreading code;

a second discrete time amplitude modulator configured for generating a second product signal by spreading second symbols of a complimentary amplitude modulated signal using a second spreading code;

a first combiner configured for combining said first and second product signals to form a protected data communication signal including first data recoverable by at least one receiver of a plurality of receivers; and

a second combiner configured for combining a global data communication signal and said protected data communication signal to form an output signal having a spread spectrum format;

wherein said global data communication signal is generated using a digital modulation process and includes second data recoverable by all of said plurality of receivers.

12. The communication system according to claim 11, wherein said first and second spreading codes include pseudo-random number sequences.

13. The communication system according to claim 11, wherein said first and second spreading codes include digitally generated chaotic sequences.

14. The communication system according to claim 11, wherein said second spreading code is orthogonal or statistically orthogonal to said first spreading code.

15. The communication system according to claim 11, wherein said digital modulation process includes a phase modulation process.

16. The communication system according to claim 11, wherein said first combiner is further configured for additively combining said first and second product signals to produce a constant power envelope in said protected data communication signal.

17. The communication system according to claim 11, further comprising:

a transmitter configured for transmitting said output signal to a first receiver of said plurality of receivers;

wherein said first receiver is configured for recovering said global data communication signal by de-spreading said output signal using a sum of a third spreading code and a fourth spreading code which are respectively identical to said first spreading code and said second spreading code.

18. The communication system according to claim 17, wherein said first and third spreading codes are synchronized in time and said second and fourth spreading codes are synchronized in time.

19. The communication system according to claim 17, wherein said first receiver is prevented from independently recovering said third spreading code or said fourth spreading code.

20. The communication system according to claim 11, further comprising:

a transmitter configured for transmitting said output signal to a first receiver of said plurality of receivers;

wherein said first receiver is configured for recovering said first product signal by de-spreading said output using a third spreading code that is identical to said first spreading code.