Communications system employing orthogonal chaotic spreading codes

• US 8,406,276 B2
• Filed: 12/29/2008
• Issued: 03/26/2013
• Est. Priority Date: 12/29/2008
• 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): Payne, David C.
• Assistant Examiner(s): Cadeau, Wednel
• Application Number:
  US12/344,962
• Publication Number:
  US 20100166041A1
• Time in Patent Office: 1,548 Days
• Field of Search: 375/146, 370/141, 370/441
• US Class Current: 375/141
• CPC Class Codes: H04B 1/707 using direct sequence modulation
• CPC Class Codes: H04J 13/0018 Chaotic
• CPC Class Codes: H04J 13/12 Generation of orthogonal codes
• CPC Class Codes: H04L 2209/12 Details relating to cryptographic hardware or logic circuitry
• CPC Class Codes: H04L 2209/80 Wireless network architectures or network communication protocols for wireless network security H04W12/00
• CPC Class Codes: H04L 9/001 using chaotic signals

Abstract

Methods for code-division multiplex communications. The methods involve generating orthogonal or statistically orthogonal chaotic spreading codes (CSC₁, . . . , CSC_K) using different sets of polynomial equations (f₀(x(nT)), . . . , f_N-1(x(nT))), different constant values (C₀, C₁, . . . , C_N-1) for the polynomial equations, or different sets of relatively prime numbers (p₀, p₁, . . . , p_N-1) as modulus (m₀, m₁, . . . , m_N-1) in solving the polynomial equations. The methods also involve forming spread spectrum communications signals using the orthogonal or statistically orthogonal chaotic spreading codes, respectively. The method further involve concurrently transmitting the spread spectrum communications signals over a common RF frequency band.

Claims

1. A method for code-division multiplex communications, comprising:

generating each of a plurality of orthogonal or statistically orthogonal chaotic spreading codes using a respective one of a plurality of different sets of modular polynomial equations of a third order or higher, where at least two polynomial equations of each of said plurality of different sets of modular polynomial equations differ with respect to polynomial degree; and

where a statistically expected value of an inner product of each said plurality of orthogonal or statistically orthogonal chaotic spreading codes is zero;

forming a plurality of spread spectrum communications signals respectively using said plurality of orthogonal or statistically orthogonal chaotic spreading codes; and

concurrently transmitting said plurality of spread spectrum communication signals over a common RF frequency band.

2. The method according to claim 1, wherein a plurality of solutions for each of said plurality of different sets of modular polynomial equations is iteratively computed and expressed as a plurality of RNS residue values.

3. The method according to claim 2, wherein said generating step further comprises determining a series of digits in a weighted number system based on said plurality of RNS residue values.

4. The method according to claim 3, wherein said generating step further comprises selecting a value for each of N moduli comprising a respective moduli set in an RNS used for respectively solving each of said plurality of different sets of modular polynomial equations.

5. The method according to claim 4, wherein said moduli set is different for each of said plurality of different sets of modular polynomial equations.

6. The method according to claim 1, wherein said plurality of different sets of modular polynomial equations differ with respect to at least one characteristic selected from the group comprising a constant and a polynomial degree.

7. The method according to claim 1, wherein said generating step further comprises selecting a plurality of relatively prime numbers to be used as modulus in solving each of said plurality of different sets of modular polynomial equations.

8. The method according to claim 1, further comprising:

receiving said plurality of spread spectrum communications signals at a receiver;

generating at least one chaotic de-spreading code; and

de-spreading at least one of said spread spectrum communication signals using said chaotic de-spreading code.

9. The method according to claim 1, further comprising:

receiving said plurality of spread spectrum communications signals at a receiver;

generating a plurality of chaotic de-spreading codes; and

de-spreading a plurality of said spread spectrum communication signals using said plurality of chaotic de-spreading codes.

10. The method according to claim 9, further comprising synchronizing said at least one of said plurality of chaotic de-spreading codes in time and frequency with at least one of said plurality of chaotic spreading codes.

11. A method for code-division multiplex communications, comprising:

generating a plurality of orthogonal or statistically orthogonal chaotic spreading codes using residue number system (RNS) arithmetic operations to respectively determine a plurality of solutions for each of a respective one of a plurality of sets of modular polynomial equations of a third order or higher, where at least two polynomial equations of each of said plurality of sets of modular polynomial equations differ with respect to polynomial degree; and

where a statistically expected value of an inner product of each said plurality of orthogonal or statistically orthogonal chaotic spreading codes is zero;

selecting a different moduli sets for each set of modular polynomial equations, each moduli set comprising a value for each of N moduli in said RNS used for determining said plurality of solutions;

forming a plurality of spread spectrum communications signals respectively using said plurality of orthogonal or statistically orthogonal chaotic spreading codes; and

concurrently transmitting said plurality of spread spectrum communication signals over a common RF frequency band.

12. The method according to claim 11, wherein said plurality of solutions are iteratively computed and expressed as RNS residue values.

13. The method according to claim 12, wherein said generating step further comprises determining a series of digits in a weighted number system based on said plurality of RNS residue values.

14. The method according to claim 11, wherein said sets of modular polynomial equations differ with respect to at least one characteristic selected from the group comprising a constant and a polynomial degree.

15. The method according to claim 11, further comprising:

receiving said plurality of spread spectrum communications signals at a receiver;

generating at least one chaotic de-spreading code; and

de-spreading at least one of said spread spectrum communication signals using said chaotic de-spreading code.

16. The method according to claim 11, further comprising:

receiving said plurality of spread spectrum communications signals at a receiver;

generating a plurality of chaotic de-spreading codes; and

de-spreading a plurality of said spread spectrum communication signals using said plurality of chaotic de-spreading codes.

17. The method according to claim 16, further comprising synchronizing said at least one of said plurality of chaotic de-spreading codes in time and frequency with at least one of said plurality of chaotic spreading codes.

18. A code-division multiplex communications system, comprising:

a plurality of transmitters configured to

(a) generate a plurality of orthogonal or statistically orthogonal chaotic spreading codes respectively using a plurality of different sets of modular polynomial equations of a third order or higher, where at least two polynomial equations of each of said plurality of different sets of modular polynomial equations differ with respect to polynomial degree, and where a statistically expected value of an inner product of each said plurality of orthogonal or statistically orthogonal chaotic spreading codes is zero;

(b) form a plurality of spread spectrum communications signals respectively using said plurality of orthogonal or statistically orthogonal chaotic spreading codes, and

(c) concurrently transmit said plurality of spread spectrum communication signals over a common RF frequency band.

19. The code-division multiplex communications system according to claim 18, wherein a plurality of solutions for each of said plurality of different sets of modular polynomial equations are iteratively computed and expressed as a plurality of RNS residue values.

20. The code-division multiplex communications system according to claim 19, wherein each of said plurality of orthogonal or statistically orthogonal chaotic spreading codes is generated by determining a series of digits in a weighted number system based on said plurality of RNS residue values.

21. The code-division multiplex communications system according to claim 20, wherein each of said plurality of orthogonal or statistically orthogonal chaotic spreading codes is generated by selecting a value for each of N moduli comprising a respective moduli set in an RNS used for respectively solving each said set of modular polynomial equations.

22. The code-division multiplex communications system according to claim 21, wherein said moduli set is different for each said set of modular polynomial equations.

23. The code-division multiplex communications system according to claim 18, wherein said sets of modular polynomial equations differ with respect to at least one characteristic selected from the group comprising a constant and a degree.

24. The code-division multiplex communications system according to claim 18, wherein each of said plurality of orthogonal or statistically orthogonal chaotic spreading codes is generated by selecting a plurality of relatively prime numbers to be used as modulus in solving each set of modular polynomial equations.

25. The method according to claim 18, further comprising:

receiving said plurality of spread spectrum communications signals at a receiver;

generating a plurality of chaotic de-spreading codes; and

de-spreading a plurality of said spread spectrum communication signals using said plurality of chaotic de-spreading codes;

wherein said at least one of said plurality of chaotic de-spreading codes is synchronized in time and frequency with at least one of said plurality of chaotic spreading codes.