RECEIVING A SPREAD SPECTRUM SIGNAL

• US 20010050948A1
• Filed: 06/23/1997
• Published: 12/13/2001
• Est. Priority Date: 06/23/1997
• Status: Active Grant

• Current Assignee: Landis+Gyr Innovations Incorporated (Landis+Gyr Group AG)
• Original Assignee: Atos Origin IT Services Incorporated (SLB)
• Inventors: FULTON, FORREST F., RAMBERG, ERIK A., FROELICH, ROBERT K.
• Granted Patent: US 6,628,699 B2
• Time in Patent Office: Days
• US Class Current: 375/148
• CPC Class Codes: H04B 1/70752 Partial correlation
• CPC Class Codes: H04B 1/708 Parallel implementation
• CPC Class Codes: H04B 1/7085 using a code tracking loop, e.g. a delay-locked loop

Abstract

A receiver for use in a spread spectrum communication system includes the following components: an acquisition system configured to detect a transmitted spread spectrum signal by simultaneously correlating multiple search phases of a reference spreading signal against an output from a receiver channel; a demodulation system configured to recover data embedded in the spread spectrum signal by simultaneously correlating the spread spectrum signal with multiple possible data phases of the reference spreading signal over consecutive data periods; and a bank of correlating devices configured for use both in the acquisition system and in the demodulation system.

Claims

1. A receiver for use in a spread spectrum communication system, the receiver comprising:

an acquisition system configured to detect a transmitted spread spectrum signal by simultaneously correlating multiple search phases of a reference spreading signal against an output from a receiver channel;

a demodulation system configured to recover data embedded in the spread spectrum signal by simultaneously correlating the spread spectrum signal with multiple possible data phases of the reference spreading signal over consecutive data periods; and

a bank of correlating devices configured for use both in the acquisition system and in the demodulation system.

2. The receiver of

claim 1

, wherein each of the correlation devices is configured to compare the spread spectrum signal against a different one of the search phases when the correlating devices are configured for use in the acquisition system.

3. The receiver of

claim 1

, wherein each of the correlation devices is configured to compare the spread spectrum signal against a different one of the data phases when the correlating devices are configured for use in the demodulation system.

4. The receiver of

claim 1

, wherein each correlating device includes:

a multiplication element configured to multiply the spread spectrum signal with the reference spreading signal to produce a product output; and

an accumulation element configured to produce an accumulation output by accumulating the product output over each of the data periods.

5. The receiver of

claim 4

, wherein each correlating device also includes a delay element configured to phase shift the accumulation output by 180°

.

6. The receiver of

claim 5

, wherein the accumulation element is configured to subtract from the product output the 180°

phase shifted version of the accumulation output.

7. The receiver of

claim 1

, further including an analog-to-digital converter configured to sample the spread spectrum signal at a selected sampling rate.

8. The receiver of

claim 7

, wherein the correlating devices are configured to process the spread spectrum signal at a center frequency equal to approximately one-quarter the sampling rate.

9. A receiver for use in processing a spread spectrum signal containing data that is CCSK-modulated onto a pseudo-noise (PN) spreading sequence, the receiver comprising:

an analog-to-digital converter configured to sample the spread spectrum signal at a selected sampling rate;

multiple correlation devices, each of which includes;

a multiplication element configured to multiply the sampled spread spectrum signal against a copy of the PN sequence at a selected code phase and to produce a corresponding product output at a center frequency less than the sampling rate and greater than zero; and

an accumulation element configured to accumulate the product output at the center frequency to produce an accumulation output; and

a processing element configured to determine which, if any, of the accumulation outputs indicates alignment between the spread spectrum signal and the copy of the PN sequence in one of the correlation devices.

10. The receiver of

claim 9

, wherein the center frequency equals approximately one-quarter the sampling rate.

11. The receiver of

claim 9

, wherein each accumulation element is configured to produce the accumulation output by subtracting from the product output an 180°

phase-shifted version of the accumulation output.

12. A method for use in receiving signals in a spread spectrum communication system, the method comprising:

acquiring a transmitted spread spectrum signal by simultaneously correlating multiple search phases of a reference spreading signal against an output from a receiver channel;

recovering data embedded in the spread spectrum signal by simultaneously correlating the spread spectrum signal with multiple possible data phases of the reference spreading signal over consecutive data periods; and

using a single bank of correlating devices both in acquiring the spread spectrum signal and in recovering data embedded in the spread spectrum signal.

13. The method of

claim 12

, wherein acquiring the transmitted spread spectrum signal includes using each of the correlation devices to compare the spread spectrum signal against a different one of the search phases.

14. The method of

claim 12

, wherein recovering data embedded in the spread spectrum signal includes using each of the correlation devices to compare the spread spectrum signal against a different one of the data phases.

15. The method of

claim 12

, further including, within each correlation device:

multiplying the spread spectrum signal with the reference spreading signal to produce a product output; and

producing an accumulation output by accumulating the product output over each of the data periods.

16. The method of

claim 15

, further including, within each correlation device, phase-shifting the accumulation output by 180°

.

17. The method of

claim 16

, further including subtracting from the product output the 180°

phase shifted version of the accumulation output.

18. The method of

claim 12

, further including sampling the spread spectrum signal at a selected sampling rate.

19. The method of

claim 18

, further including using the correlation devices to process the spread spectrum signal at a center frequency equal to approximately one-quarter the sampling rate.