Superimposed composite channel filter

• US 7,907,513 B2
• Filed: 03/03/2008
• Issued: 03/15/2011
• Est. Priority Date: 03/02/2007
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Proctor, James A. Jr., Otto, James C., Gainey, Kenneth M.
• Primary Examiner(s): Qureshi; Afsar M.
• Application Number:
  US12/041,626
• Publication Number:
  US 20080232241A1
• Time in Patent Office: 1,107 Days
• Field of Search: 370208-342, 370509-519, 375137-376, 375/E1.025, 375/E1.032, 375/E1.002, 455/502, 455/506, 725/127
• US Class Current: 370/210
• CPC Class Codes: H04B 7/15542 Selecting at relay station its transmit and receive resources selection of wireless resources by user or terminal H04W72/02; arrangements affording multiple use of the transmission path by two-dimensional division of the resources H04L5/0003, or by allocating sub-channels H04L5/003
• CPC Class Codes: H04B 7/15571 by signal isolation, e.g. isolation by frequency or by antenna pattern, or by polarization
• CPC Class Codes: H04B 7/15585 by interference cancellation

Abstract

Methods and systems are provided to generate digital coefficients for a filter. The generation of coefficients relies on a Fourier transformation of an impulse response in time domain that is zero padded, e.g., zeros are appended to an array corresponding to a sampled input signal of length M. A unit prototypical filter is generated through a frequency domain response of length N_FFT=N_S+M−1, wherein N_S is a sampling length of the incoming signal. The unit prototypical filter is then circularly shifted in order to generate a band pass filter centered at a desired frequency. Circularly shifted filters are point-to-point added to generate a set of composite digital coefficients to filter the incoming signal. The reference frequencies for the composite filter are extracted from a message received from one or more base stations associated with one or more service providers. The composite filter typically operates on a frequency repeater.

Claims

1. A method for generating digital filter coefficients utilized in a wireless environment, the method comprising:

appending zeros to an M-sample impulse response in time domain to create a zero padded impulse response of N_FFT in length, wherein M and N_FFT are positive integers;

Fourier transforming the _NFFT length zero-padded impulse response;

performing a circular shift of the Fourier-transformed zero-padded impulse response; and

adding in frequency domain a set of circularly-shifted, Fourier-transformed zero-padded impulse responses to generate a set of composite digital filter coefficients.

2. The method of claim 1, further comprising:

adding in frequency domain a set of circularly-shifted, Fourier-transformed zero-padded impulse responses to generate composite digital filter coefficients; and

performing an inverse Fourier transform of the frequency domain composite digital filter coefficients to obtain a composite time domain digital filter impulse response.

3. The method of claim 1, further comprising conveying the generated filter coefficients to a frequency bin multiplier block.

4. The method of claim 3, further comprising applying the generated digital filter coefficients to a set of frequency domain bins of a block of signal to be repeated.

5. The method of claim 4, generating a set of frequency domain bins of a block of signal by appending N_S time domain signal samples with zeros to form a N_FFT block of zero padded time samples, wherein N_S and N_FFT are a positive integers;

and, performing a Fourier transform of the zero padded time sample to produce a set of frequency domain bins.

6. The method of claim 5, wherein N_FFT is equal to or greater than M+N_S−

1.

7. The method of claim 4, wherein the generated composite digital filter coefficients are designed to filter a predetermined set of frequencies to be repeated.

8. The method of claim 7, wherein in the M-sample impulse response is designed to match at least one industry standardized waveform property.

9. The method of claim 8, the set of frequencies to be repeated comprising a set of sub-bands within an operating band of a service provider.

10. The method of claim 8, the set of frequencies to be repeated comprising a set of predetermined frequencies associated with the service provider.

11. The method of claim 10, the message is at least one of a broadcast channel or a management frame, or a directed message, or an short message service message.

12. The method of claim 7, wherein the set of frequencies to be repeated is determined by carrying out the following acts:

receiving a message carrying an indication of the set of frequencies;

extracting the set of frequencies from the indication within the message.

13. The method of claim 12, the cell search is conducted by a modem residing in a repeater.

14. The method of claim 13, wherein the predetermined set of frequencies is stored in the frequency repeater.

15. The method of claim 7, the set of frequencies to be repeated is acquired in a cell search of the cellular signals.

16. The method of claim 3, further comprising storing the generated filter mask in a repeater.

17. The method of claim 1, further comprising generating the M-bin impulse response in time domain.

18. A wireless device comprising:

a processor configured to generate an M sample impulse response in time domain, to perform an array padding operation, wherein M is a positive integer;

to compute a Fourier transformation of at least one of the M-bin impulse response or an N_FFT-bin frequency sequence, wherein N_FFT is a positive integer;

perform a circular shift of an N_FFT-bin Fourier transformed impulse response;

to add a set of Fourier transformed zero-padded impulse responses;

to generate a composite mask filter utilizing the added Fourier-transformed impulse responses; and

a memory coupled to the processor.

19. The device of claim 18, the processor further configured to convey the generated filter mask to a frequency bin multiplier block.

20. The device of claim 19, the processor further configured to apply the generated filter mask to a set of frequency domain bins of a block of signal to be repeated.

21. The device of claim 20, the block of signal to be repeated comprises a set of sub-bands within an operating band of a service provider.

22. The device of claim 21, the set of sub-bands comprising a set of predetermined frequencies associated with the service provider.

23. The device of claim 21, wherein the set of sub-bands is determined by carrying out the following acts:

receiving a message carrying an indication of the set of frequencies;

extracting the set of frequencies from the indication within the message.

24. The device of claim 18, the processor further configured to store the generated composite set of filter coefficients.

25. An apparatus that operates in a wireless environment, the apparatus comprising:

means for zero padding an M-bin impulse response in time domain to an N_FFT-bin length, wherein M and N_FFT are positive integers;

means for Fourier transforming the N_FFT-bin zero-padded impulse response;

performing a circular shift of the Fourier-transformed zero-padded impulse response;

means for adding in frequency domain a set of circularly-shifted, Fourier-transformed zero-padded impulse responses to generate a filter mask;

means for conveying the generated filter mask to a frequency bin multiplier block; and

means for applying the generated filter mask to a set of frequency domain bins of a block of signal to be repeated.

26. A computer-readable storage medium, volatile or non-volatile, encoded with a computer program, the computer program including:

code for causing a computer to pad an M-bin impulse response in time domain to an N_FFT-bin length, wherein M and N_FFT are positive integers;

code for causing a computer to Fourier transform the N_FFT-bin zero-padded impulse response;

code for causing a computer to perform a circular shift of the Fourier-transformed zero-padded impulse response; and

code for causing a computer to add in frequency domain a set of circularly-shifted, Fourier-transformed zero-padded impulse responses to generate a filter mask; and

code for causing a computer to apply the generated filter mask to a set of frequency domain bins of a block of signal to be repeated.