Processing a sequence of samples of a signal

• US 20070116098A1
• Filed: 11/15/2006
• Published: 05/24/2007
• Est. Priority Date: 11/18/2005
• Status: Active Grant

• Current Assignee: Conversant Wireless Licensing S.à.r.l. (f/k/a Core Wireless Licensing S.a.r.l.) (MOSAID Technologies Inc. (f/k/a Conversant Intellectual Property Management))
• Original Assignee: Nokia Corporation
• Inventors: Valio, Harri, Qin, Zhengdi
• Granted Patent: US 7,830,950 B2
• Time in Patent Office: Days
• US Class Current: 375/147
• CPC Class Codes: G01S 19/24 Acquisition or tracking or demodulation of signals transmitted by the system synchronisation aspects of direct sequence spread spectrum modulation H04B1/7073

Abstract

For a method for processing a sequence of samples of a signal, it is assumed that the signal comprises a carrier that is modulated by a code composed of a sequence of chips. The method comprises wiping-off an influence by the carrier on the sequence of samples and downsampling the sequence of samples (step 105; step 205; step 301), and utilizing the downsampled sequence of samples as a new sequence of samples for further processing (step 108; step 209; step 302). Also disclosed are a corresponding processing component 72, a corresponding electronic device 71, a corresponding system, a corresponding software program code and a corresponding software program product.

Claims

1. Method for processing a sequence of samples of a signal, which signal comprises a carrier that is modulated by a code composed of a sequence of chips, said method comprising:

a) wiping-off an influence by said carrier on said sequence of samples and downsampling said sequence of samples; and

b) utilizing said downsampled sequence of samples as a new sequence of samples for further processing.

2. Method according to claim 1, wherein said samples are obtained from said signal with a sampling rate, which is at least equal to a frequency of said carrier and at least twice a chiprate of said code, and wherein said wiping-off and downsampling comprises combining respective subsequent samples of a predetermined number of said sequence of samples to obtain a sequence of combined values as said downsampled sequence of samples.

3. Method according to claim 2, wherein a respective combined value lies within a predetermined range or outside of a predetermined range, said method further comprising the following preceding b):

in case a combined value lies within said predetermined range, shifting said sequence of samples by one sample and combining respective subsequent samples of a predetermined number of said shifted sequence of samples to obtain a sequence of combined values.

4. Method according to claim 3, wherein said predetermined range comprises only a single value of zero.

5. Method according to claim 2, further comprising shifting said sequence of samples by one sample and combining respective subsequent samples of a predetermined number of said shifted sequence of samples to obtain a further sequence of combined values, wherein b) comprises utilizing said sequence of combined values and said further sequence of combined values as a respective new sequence of samples for further processing in which an influence by said carrier has been wiped-off, and combining said processed sequence of combined values and said processed further sequence of combined values to a single sequence of values.

6. Method according to claim 2, wherein said combining respective subsequent samples comprises combining respective two subsequent samples.

7. Method according to claim 2, wherein said carrier is a binary offset carrier and wherein said code is a pseudo-random noise code.

8. Method according to claim 7, wherein said binary offset carrier is a BOC(n,n), with n being a natural number, wherein said sampling rate is four samples per chip of said pseudo-random noise code, said sequence of samples being denoted by

X={x₁,x₂,x₃,x₄,x₆, . . . }, and wherein said combining is performed by applying the following equation on said sequence of samples:

Y={[y₁,y₂], . . . , [y_2n+1,y_2n+2], . . . }

where

y_2n+1=(x_4n+1+x_4n+2)/2 (n=0,1,2,3, . . . )
y_2n+2=−

(x_4n+3+x_4n+4)/2

Y being said sequence of combined values.

9. Method according to claim 2, wherein said binary offset carrier is a BOC(2n,n), with n being a natural number, wherein said sampling rate is four samples per chip of said pseudo-random noise code, said sequence of samples being denoted by

X={x₁,x₂,x₃,x₄,x₆, . . . }, and wherein said combining is performed by applying the following equation on said sequence of samples:

Y={y₁, y₂,y₃, . . . }

where

y_n=(x_2n+1−

x_2n+2)/2 (n=0,1,2,3, . . . )

Y being said sequence of combined values.

10. Method according to claim 1, wherein said further processing in b) comprises a decoding using at least one of a matched filter and a correlator.

11. Method according to claim 1, wherein said signal originates from a Global Navigation Satellite Systems signal, which is modulated with said modulated carrier.

12. Processing module for processing a sequence of samples of a signal, which signal comprises a carrier that is modulated by a code composed of a sequence of chips, said processing module comprising:

a carrier wipe-off and downsampling portion adapted to wipe-off an influence by said carrier on said sequence of samples and to downsample said sequence of samples; and

a processing component adapted to utilize a downsampled sequence of samples provided by said carrier wipe-off and downsampling portion as a new sequence of samples for further processing.

13. Electronic device comprising a processing module according to claim 12.

14. System comprising an electronic device having a processing module for processing a sequence of samples of a signal, which signal comprises a carrier that is modulated by a code composed of a sequence of chips, said processing module comprising:

a carrier wipe-off and downsampling portion adapted to wipe-off an influence by said carrier on said sequence of samples and to downsample said sequence of samples; and

a processing component adapted to utilize a downsampled sequence of samples provided by said carrier wipe-off and downsampling portion as a new sequence of samples for further processing.

15. Software program code for processing a sequence of samples of a signal, which signal comprises a carrier that is modulated by a code composed of a sequence of chips, said software program code being adapted to realize the following when being executed by a processing unit:

a) wiping-off an influence by said carrier on said sequence of samples and downsampling said sequence of samples; and

b) utilizing said downsampled sequence of samples as a new sequence of samples for further processing.

16. Software program product in which a software program code according to claim 15 is stored.