Hybrid spread-spectrum technique for expanding channel capacity

• US 7,092,440 B1
• Filed: 09/27/2000
• Issued: 08/15/2006
• Est. Priority Date: 09/27/2000
• Status: Expired due to Fees

• Current Assignee: UT-Battelle LLC
• Original Assignee: UT-Battelle LLC
• Inventors: Smith, Stephen F., Moore, Michael R., Dress, William B. Jr.
• Primary Examiner(s): Bayard, Emmanuel
• Assistant Examiner(s): Pathak, Sudhanshu C.
• Application Number:
  US09/671,636
• Time in Patent Office: 2,148 Days
• Field of Search: 375/131, 375/201, 375/134, 375/239, 375/148, 375/130, 375/260, 375/202, 455/552, 370/342, 370/480, 370/208, 370/350, 370/343, 370/335, 370/525, 370/203, 370/330, 332/103
• US Class Current: 375/140
• CPC Class Codes: H04B 1/692 Hybrid techniques using combinations of two or more spread spectrum techniques
• CPC Class Codes: H04J 13/0022 PN, e.g. Kronecker
• CPC Class Codes: H04L 5/026 using code division

Abstract

Methods, systems and devices are described for a direct-sequence spread-spectrum communication scheme that increases the number of users by utilizing a plurality of closely spaced orthogonal carriers that produce overlapping spectra. A method includes overlapping a plurality of direct-sequence spread-spectrum signals using carrier frequencies that are orthogonally spaced relative to a bit rate. The methods, systems and devices provide advantages because they can accommodate an increase in the number of normalized users and can optimize the loading of users across multiple frequency channels.

Claims

1. A method, comprising overlapping a plurality of direct-sequence spread-spectrum signals using carrier frequencies that are i) each precisely an integer multiple of a bit rate and ii) orthogonally spaced relative to an integral multiple of the bit rate rather than a chip rate,

wherein the chip rate is an integer multiple of the bit rate and is greater than or equal to two and

wherein the product of two of the plurality of direct-sequence spread-spectrum signals, independent of their relative starting phases, will integrate to zero and an integration time to define orthogonality is 1/Tb, where 1/Tb the bit rate.

2. A method of claim 1, further comprising common frequency-hopping encoding said plurality of direct-sequence spread-spectrum signals.

3. The method of claim 1, further comprising individual, differential frequency-hopping encoding each of said plurality of direct-sequence spread-spectrum signals.

4. The method of claim 1, wherein frequency-hopping modulation is performed in a continuous-phase manner.

5. The method of claim 1, further comprising time-hopping encoding said plurality of direct-sequence spread-spectrum signals.

6. The method of claim 5, further comprising frequency-hopping encoding said plurality of direct-sequence spread-spectrum signals.

7. The method of claim 1, wherein overlapping includes synchronously allocating each of a plurality of users to one of a plurality of orthogonal channels.

8. The method of claim 1, wherein overlapping includes encoding a frequency shift in a subset of bits that define a code word.

9. The method of claim 1, wherein overlapping includes establishing a bit-clock synchronization;

and

further comprising multiplying an incoming signal by an estimate of a desired signal; and

integrating a product over an integral multiple of a bit period rather than a chip period.

10. The method of claim 1, further comprising retransmitting one of said plurality of direct-sequence spread-spectrum signals.

11. The method of claim 1, further comprising checking one of said plurality of direct-sequence spread-spectrum signals with an error-correcting code.

24. The method of claim 1, wherein integration to zero is characterized by

${\int }_{}^{}$

t t + T x ⁢

cos ( ⁢

ω

1 ⁡

( t ) ) * PN 1 ⁡

( t ) * m 1 ⁡

( t ) * cos ⁡

( ω

2 ⁡

( t ) ) * PN 2 ⁡

( t ) * m 2 ⁡

( t ) ⁢

ⅆ

t = 0

where ω

₁ is a first carrier frequency, ω

₂ is a second carrier frequency, PN₁ is a first spreading code, PN₂ is a second spreading code, m₁ is a first digital message signal, m₂ is a second digital message signal, t is time and T_x is set equal to T_b or integral multiples of T_b, where 1/T_b is a data rate.

30. The method of claim 1, further comprising cycling through a set of frequencies in a manner known to a receiver.

12. A computer program stored on a computer readable medium comprising computer- or machine-readable program elements translatable for implementing a method of signal transmission including overlapping a plurality of direct-sequence spread-spectrum signals using carrier frequencies that are i) each precisely an integer multiple of a bit rate and ii) orthogonally spaced relative to an integral multiple of the bit rate rather than a chip rate,

wherein the chip rate is an integer multiple of the bit rate and is greater than or equal to two and

wherein the product of two of the plurality of direct-sequence spread-spectrum signals, independent of their relative starting phases, will integrate to zero and an integration time to define orthogonality is 1/Tb, where 1/Tb the bit rate.

25. The computer program of claim 12, wherein integration to zero is characterized by

${\int }_{}^{}$

t t + T x ⁢

cos ( ⁢

ω

1 ⁡

( t ) ) * PN 1 ⁡

( t ) * m 1 ⁡

( t ) * cos ⁡

( ω

2 ⁡

( t ) ) * PN 2 ⁡

( t ) * m 2 ⁡

( t ) ⁢

ⅆ

t = 0

where ω

₁ is a first carrier frequency, ω

₂ is a second carrier frequency, PN₁ is a first spreading code, PN₂ is a second spreading code, m₁ is a first digital message signal, m₂ is a second digital message signal, t is time and T_x is set equal to T_b or integral multiples of T_b, where 1/T_b is a data rate.

31. The computer program of claim 12, further comprising cycling through a set of frequencies in a manner known to a receiver.

13. A computer program stored on a computer readable medium comprising computer program means adapted to perform the steps of overlapping a plurality of direct-sequence spread-spectrum signals using carrier frequencies that are i) each precisely an integer multiple of a bit rate and ii) orthogonally spaced relative to an integral multiple of the bit rate rather than a chip rate,

wherein the chip rate is an integer multiple of the bit rate and is greater than or equal to two and

wherein the product of two of the plurality of direct-sequence spread-spectrum signals, independent of their relative starting phases, will integrate to zero and an integration time to define orthogonality is 1/Tb, where 1/Tb the bit rate.

26. The computer program of claim 13, wherein integration to zero is characterized by

${\int }_{}^{}$

t t + T x ⁢

cos ( ⁢

ω

1 ⁡

( t ) ) * PN 1 ⁡

( t ) * m 1 ⁡

( t ) * cos ⁡

( ω

2 ⁡

( t ) ) * PN 2 ⁡

( t ) * m 2 ⁡

( t ) ⁢

ⅆ

t = 0

where ω

₁ is a first carrier frequency, ω

₂ is a second carrier frequency, PN₁ is a first spreading code, PN₂ is a second spreading code, m₁ is a first digital message signal, m₂ is a second digital message signal, t is time and T_x is set equal to T_b or integral multiples of T_b, where 1/T_b is a data rate.

32. The computer program of claim 13, further comprising cycling through a set of frequencies in a manner known to a receiver.

14. A method, comprising providing a direct-sequence spread-spectrum communication system that increases a number of users by utilizing a plurality of closely spaced orthogonal carriers that are i) each precisely an integer multiple of a bit rate and ii) produce overlapping spectra,

wherein a spacing of the plurality of orthogonal carriers is based on an integral multiple of the bit rate and not a chip rate,

wherein the chip rate is an integer multiple of the bit rate and is greater than or equal to two and

wherein the product of two of the plurality of direct-sequence spread-spectrum signals, independent of their relative starting phases, will integrate to zero and an integration time to define orthogonality is 1/Tb, where 1/Tb the bit rate.

15. The method of claim 14, further comprising frequency-hopping encoding the overlapping spectra.

16. The method of claim 14, further comprising time-hopping encoding the overlapping spectra.

17. The method of claim 16, further comprising frequency-hopping encoding the overlapping spectra.

27. The method of claim 14, wherein integration to zero is characterized by

${\int }_{}^{}$

t t + T x ⁢

cos ( ⁢

ω

1 ⁡

( t ) ) * PN 1 ⁡

( t ) * m 1 ⁡

( t ) * cos ⁡

( ω

2 ⁡

( t ) ) * PN 2 ⁡

( t ) * m 2 ⁡

( t ) ⁢

ⅆ

t = 0

where ω

₁ is a first carrier frequency, ω

₂ is a second carrier frequency, PN₁ is a first spreading code, PN₂ is a second spreading code, m₁ is a first digital message signal, m₂ is a second digital message signal, t is time and T_x is set equal to T_b or integral multiples of T_b, where 1/T_b is a data rate.

33. The method of claim 14, further comprising cycling through a set of frequencies in a manner known to a receiver.

18. A method, comprising overlapping a plurality of synchronous direct-sequence spread-spectrum signals using carrier frequencies with zero relative phase differences that are i) each precisely an integral multiple of ½

a bit rate and ii) orthogonally spaced relative to an integral multiple of ½

the bit rate rather than a chip rate,

wherein the chip rate is an integral multiple of the bit rate and is greater than or equal to two and

wherein the product of two of the plurality of direct-sequence spread-spectrum signals, independent of their relative starting phases, will integrate to zero and an integration time to define orthogonality is 1/Tb, where 1/Tb the bit rate.

19. The method of claim 18, further comprising common frequency-hopping encoding said plurality of direct-sequence spread-spectrum signals.

21. The method of claim 18, further comprising time-hopping encoding said plurality of direct-sequence spread-spectrum signals.

28. The method of claim 18, wherein integration to zero is characterized by

${\int }_{}^{}$

t t + T x ⁢

cos ( ⁢

ω

1 ⁡

( t ) ) * PN 1 ⁡

( t ) * m 1 ⁡

( t ) * cos ⁡

( ω

2 ⁡

( t ) ) * PN 2 ⁡

( t ) * m 2 ⁡

( t ) ⁢

ⅆ

t = 0

where ω

₁ is a first carrier frequency, ω

₂ is a second carrier frequency, PN₁ is a first spreading code, PN₂ s a second spreading code, m₁ is a first digital message signal, m₂ is a second digital message signal, t is time and T_x is set equal to T_b or integral multiples of T_b, where 1/T_b is a data rate.

34. The method of claim 18, further comprising cycling through a set of frequencies in a manner known to a receiver.

20. A method, comprising overlapping a plurality of synchronous direct-sequence spread-spectrum signals using carrier frequencies with relative phase differences that are i) each precisely an integral multiple of ½

^x a bit rate, where x is a counting number and an integer and ii) orthogonally spaced relative to one half the integral multiple of ½

^x of the bit rate rather than a chip rate,

wherein the chip rate is an integral multiple of the bit rate and is greater than or equal to two and

wherein the product of two of the plurality of direct-sequence spread-spectrum signals, independent of their relative starting phases, will integrate to zero and an integration time to define orthogonality is 1/Tb, where 1/Tb the bit rate.

22. The method of claim 20 further comprising common frequency-hopping encoding said plurality of direct-sequence spread-spectrum signals.

23. The method of claim 20, further comprising time-hopping encoding said plurality of direct-sequence spread-spectrum signals.

29. The method of claim 20, wherein integration to zero is characterized by

${\int }_{}^{}$

t t + T x ⁢

cos ( ⁢

ω

1 ⁡

( t ) ) * PN 1 ⁡

( t ) * m 1 ⁡

( t ) * cos ⁡

( ω

2 ⁡

( t ) ) * PN 2 ⁡

( t ) * m 2 ⁡

( t ) ⁢

ⅆ

t = 0

where ω

₁ is a first carrier frequency, ω

₂ is a second carrier frequency, PN₁ is a first spreading code, PN₂ is a second spreading code, m₁ is a first digital message signal, m₂ is a second digital message signal, t is time and T_x is set equal to T_b or integral multiples of T_b, where 1/T_b is a data rate.

35. The method of claim 20, further comprising cycling through a set of frequencies in a manner known to a receiver.