System and method for baseband removal of narrowband interference in ultra wideband signals

• US 6,834,073 B1
• Filed: 10/10/2000
• Issued: 12/21/2004
• Est. Priority Date: 05/26/2000
• Status: Expired due to Term

• Current Assignee: North Star Innovations Inc. (Wi-LAN Inc.)
• Original Assignee: Freescale Semiconductor, Inc. (NXP Semiconductors NV)
• Inventors: McCorkle, John W., Miller, Timothy R.
• Primary Examiner(s): Tran, Khai
• Application Number:
  US09/685,203
• Time in Patent Office: 1,533 Days
• Field of Search: 375/130, 375/140, 375/146, 375/131, 375/295, 375/147, 375/149, 375/346, 370/324, 370/213
• US Class Current: 375/130
• CPC Class Codes: G01S 13/0209 Systems with very large relative bandwidth, i.e. larger than 10 %, e.g. baseband, pulse, carrier-free, ultrawideband
• CPC Class Codes: G01S 7/023 Interference mitigation, e.g. reducing or avoiding non-intentional interference with other HF-transmitters, base station transmitters for mobile communication or other radar systems, e.g. using electro-magnetic interference [EMI] reduction techniques auxiliary means for detecting or identifying radar signals or the like G01S7/021; means for anti-jamming G01S7/36
• CPC Class Codes: H04B 1/69 Spread spectrum techniques
• CPC Class Codes: H04B 1/71637 Receiver aspects H04B1/7183 takes precedence
• CPC Class Codes: H04B 1/719 Interference-related aspects
• CPC Class Codes: H04B 1/74 for increasing reliability, e.g. using redundant or spare channels or apparatus replacing by standby devices for amplifiers H03F1/52, H03F1/542
• CPC Class Codes: H04L 25/4902 Pulse width modulation; Pulse position modulation
• CPC Class Codes: H04L 27/0004 using wavelets

Abstract

A system, method, and computer program product for baseband removal of narrowband interference contained within UWB signals in a UWB receiver. The RFI is extracted from the UWB signal by employing a filter that is matched approximately with the RFI in the baseband signal, extracting RFI, and passing the desired data signal unscathed.

Claims

1. A baseband RFI extraction mechanism configured to pass an ultra wideband (UWB) signal while suppressing a narrowband interference signal that overlaps said UWB signal in frequency and has been undersampled, comprising:

a filter configured to identify a frequency of said narrowband interference signal after having been undersampled in order to extract said narrowband interference signal from said UWB signal at baseband, wherein

said filter including a narrowband interference identification mechanism that is configured to identify the frequency of said narrowband interference signal and change filter parameters of said filter to suppress said narrowband interference signal at said frequency.

2. The baseband RFI mechanism of claim 1, wherein said frequency is an alias frequency of said narrowband interfere signal and said filter is configured to identify and cancel a second frequency at which another alias of said narrowband interference signal is located.

3. A UWB receiver comprising:

an A/D converter configured to digitize an incoming signal, said incoming signal including a narrowband interference signal and an ultra wideband (UWB) signal, said A/D converter having a predetermined sampling rate that is less than a Nyquist frequency for sampling said narrowband interference signal;

an RFI extraction mechanism including

a filter configured to identify and remove an undersampled version of said narrowband inference signal so as to improve a UWB signal to interference ratio; and

a detector that detects data in said UWB signal after said RFI mechanism improves the UWB signal to interference ratio by suppressing the narrowband interference signal.

4. A receiver as claimed in claim 3, wherein the A/D converter is configured to undersample said narrowband signal and cause said narrowband signal to reside in a same frequency band in which baseband processing occurs on said UWB signal.

5. A receiver as claimed in claim 3, wherein a sample rate of said A/D converter is adjustable to affect a completeness of extraction of said narrowband signal.

6. A receiver as claimed in claim 3, wherein a quantization level at which said A/D converter digitizes said incoming signal is adjustable to affect a completeness with which extraction of said narrowband signal is achieved.

7. A receiver as claimed in claim 3, wherein a vector length of said incoming signal is adjustable to affect a completeness with which extraction of said narrow band signal is achieved.

8. A receiver as claimed in claim 3, wherein the A/D converter operates at a predetermined sample rate that is set to a multiple of a bit rate of data bits in said UWB signal.

9. A baseband RFI extraction mechanism for passing a desired UWB signal portion of an incoming signal while suppressing a narrowband interference signal that overlaps said desired UWB signal, comprising:

a bit detector configured to detect bits encoded in the desired UWB signal;

a subtraction mechanism configured to subtract a portion of the UWB signal having a detected bit contained therein from said incoming signal;

an interference estimator configured to estimate the narrowband interference

signal after said subtraction mechanism removed the portion of the UWB signal

containing the bit from the incoming signal; and

a filter configured to operate at baseband and extract said narrowband interference signal from a received signal, which is a down connected version of said incoming signal, based on the estimate of the narrowband interference signal made by the interference estimator.

10. A baseband RFI extraction mechanism as claimed in claim 9, further comprising:

a signal combiner configured to subtract said desired UWB signal from said incoming signal resulting in a residual narrowband interference signal.

11. A UWB receiver comprising:

an A/D converter configured to digitize an incoming signal, said incoming signal including a narrowband interference signal and a UWB signal, said A/D converter having a predetermined sampling rate that is less than a nyquist frequency for said narrowband interference; and

a bit detector configured to detect bits encoded in the desired UWB signal;

a subtraction mechanism configured to subtract a portion of the UWB signal having a detected bit contained therein from said narrowband interference signal;

an interference estimator configured to estimate the narrowband interference

signal after said subtraction mechanism removed the portion of the UWB signal

containing the bit; and

a filter configured to extract said narrowband interference signal from the incoming signal based on the estimate of the narrowband interference signal made by the interference estimator.

12. A receiver as claim in claim 11, wherein a sample rate of said A/D converter is adjustable to affect a completeness of extraction of said narrowband interference signal.

13. A receiver as claimed in claim 11, wherein the A/D converter is configured to under sample said narrow band signal and cause said narrow band interference signal to reside in a same frequency band in which baseband processing occurs.

14. A receiver as claimed in claim 11, wherein a quantization level of said incoming signal is adjusted to affect a completeness of extraction of said narrow band interference signal.

15. A receiver as claimed in claim 11, wherein a vector length of said incoming signal is adjusted to affect a completeness of extraction of said narrow band interference signal.

16. An RFI extraction mechanism for passing a desired UWB signal while suppressing a narrowband interference signal that overlaps in frequency said UWB signal, comprising:

a bit detector configured to detect bits of the desired UWB signal part of an incoming signal, and extract said desired UWB signal from said incoming signal;

a filter configured to identify a frequency of said narrowband interference signal in order to extract said narrowband interference signal from said incoming signal; and

an estimator configured to estimate an amount said narrowband interference signal that is residual from at least one of said bit detector and said filter.

17. An RFI extraction mechanism as claimed in claim 16, further comprising:

a combiner configured to subtract said desired UWB signal from said incoming signal resulting in said residual narrowband interference signal.

18. An RFI extraction mechanism as claimed in claim 16, wherein the estimator is configured to detect a frequency of said narrowband interference signal that is provided to said filter so as to improve performance by further suppressing said narrowband interference signal in subsequent incoming signals.

19. A UWB receiver comprising:

an A/D converter configured to undersample a RFI signal residing on an incoming UWB signal;

an RFI extraction mechanism including

a bit detector configured to detect bits of an incoming UWB signal, wherein said bits are from a desired data signal encoded in said UWB signal, and extract said desired signal from said incoming signal,

a filter configured to match a narrowband interference signal to a reference signal in order to extract said narrowband interference signal, and

an estimator configured to estimate said narrowband interference signal that remains after being processed by said filter; and

a data detector configured to detect data in said UWB signal after said RFI mechanism extracts said RFI signal from said UWB signal.

20. A receiver as claimed in claim 19, wherein the A/D converter is configured to under sample said RFI signal and cause alias terms of said RFI signal to reside in a same frequency band in which baseband processing occurs.

21. A receiver as claimed in claim 19, wherein a sample rate of said A/D converter is adjustable so as to affect a completeness of extraction of said RFI signal.

22. A receiver as claimed in claim 19, wherein a quantization level of said incoming signal is adjustable so as to affect a completeness of extraction of said RFI signal.

23. A receiver as claimed in claim 19, wherein a vector length of said incoming signal is adjusted so as to affect a completeness of extraction of said RFI signal.

24. A receiver as claimed in claim 19, wherein said RFI extraction mechanism being configured to interactively update and remove said narrowband interference signal.

25. A baseband RFI extraction mechanism for passing a desired UWB signal while suppressing a narrowband interference signal that overlaps in frequency said desired UWB signal, comprising:

a narrowband interference suppression filter;

a controller configured to controllably set filter parameters of the narrowband interference suppression filter to remove the narrowband interference signal after said narrowband interference signal has been undersampled; and

a sensor configured to detect a signal energy level of said narrowband interference signal and provide feature data to said controller regarding features of said narrowband interference signal.

26. An RFI extraction mechanism as claimed in claim 25, wherein the controller further comprises:

a processor configured to calculate said filter parameters of said filter.

27. A UWB receiver comprising:

an A/D converter configured to sample an incoming UWB signal and undersample a narrowband interference signal; and

an RFI extraction mechanism including

a narrowband interference suppression filter;

a controller configured to controllably set filter parameters of the narrowband interference suppression filter to remove the narrowband interference signal after said narrowband interference signal has been undersampled; and

a sensor configured to detect a signal energy level of said narrowband interference signal and provide feature data to said controller regarding features of said narrowband interference signal; and

a data detector configured to detect data in said UWB signal after said RFI extraction mechanism extracted the narrowband interference signal.

28. A receiver as claimed in claim 27, wherein the A/D converter which under sampled said narrow band signal causes said narrow band signal to reside in a same frequency band in which base band processing occurs.

29. A receiver as claimed in claim 27, wherein a sample rate of said A/D converter is adjusted so as to affect an increased suppression of said narrow band signal.

30. A receiver as claimed in claim 27, wherein a quantization level of said incoming is adjusted to affect and increased suppression of said narrow band signal.

31. A receiver as claimed in claim 27, wherein a vector length of said incoming signal is adjustable to so as to affect increased suppression of said narrow band signal.

32. A receiver as claimed in claim 27, wherein said RFI extraction mechanism is interactively updated with different filter parameters so as to adjust for changes in said narrowband interference signal.

33. A method for changing filter parameters in order to adaptively cancel a narrowband interference signal from a UWB signal, comprising the steps of:

detecting bits of a desired UWB signal;

subtracting said bits of said UWB signal from an incoming signal in order to obtain an accurate estimate of said narrowband interference signal;

estimating a frequency of said narrowband interference signal; and

changing filter parameters of a filter to suppress said narrowband interference signal at said frequency estimated in said estimating step.

34. A method as claimed in claim 33, further comprising steps of:

subtracting said narrowband interference signal from said incoming signal so as to obtain a processed UWB signal; and

outputting said processed UWB signal.

35. A method as claimed in claim 33, wherein the estimating said narrow band interference signal step further comprises:

detecting signal energy of said narrow band interference signal; and

calculating new filter parameters for a changing filter characteristic of said filter.