Narrowband Interference Cancellation Method and Apparatus

• US 20080260080A1
• Filed: 04/23/2007
• Published: 10/23/2008
• Est. Priority Date: 04/23/2007
• Status: Abandoned Application

• Current Assignee: Telefonaktiebolaget LM Ericsson
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: Sundstrom, Lars
• Application Number:
  US11/738,606
• Publication Number:
  US 20080260080A1
• Time in Patent Office: Days
• US Class Current: 375/348
• CPC Class Codes: H04B 1/123 using adaptive balancing or compensation means adaptive filter circuits and algorithms H03H
• CPC Class Codes: H04B 1/7101 with estimation filters
• CPC Class Codes: H04B 1/7102 with transform to frequency domain

Abstract

A Cartesian Feedback-loop Signal Canceller (CFSC) recovers a signal of interest from a composite signal by cancelling a narrowband interferer from the composite signal. According to one embodiment, narrowband interference cancellation is performed by destructively combining a composite signal including a narrowband interference signal and a signal of interest with an estimate of the narrowband interference signal to generate an interference-compensated signal. A feedback signal is generated having Cartesian components derived from the interference-compensated signal. Cartesian components associated with the signal of interest are removed from the feedback signal to generate the narrowband interference signal estimate.

Claims

1. A method of narrowband interference cancellation, comprising:

destructively combining a composite signal including a narrowband interference signal and a signal of interest with an estimate of the narrowband interference signal to generate an interference-compensated signal;

generating a feedback signal having Cartesian components derived from the interference-compensated signal; and

removing Cartesian components associated with the signal of interest from the feedback signal to generate the narrowband interference signal estimate.

2. The method of claim 1, wherein destructively combining the composite signal with the narrowband interference signal estimate comprises summing the composite signal and an opposite of the narrowband interference signal estimate.

3. The method of claim 1, wherein destructively combining the composite signal with the narrowband interference signal estimate comprises destructively combining a WCDMA baseband signal including a GSM narrowband interference signal and a WCDMA signal of interest with an estimate of the GSM narrowband interference signal.

4. The method of claim 3, wherein generating a feedback signal having Cartesian components derived from the interference-compensated signal comprises demodulating the interference-compensated signal as a function of the GSM narrowband interference signal frequency.

5. The method of claim 1, wherein destructively combining the composite signal with the narrowband interference signal estimate comprises destructively combining a digital-to-analog converter output signal including a narrowband interference image and a signal of interest with an estimate of the narrowband interference image.

6. The method of claim 5, wherein generating a feedback signal having Cartesian components derived from the interference-compensated signal comprises demodulating the interference-compensated signal as a function of the narrowband interference image frequency.

7. The method of claim 1, wherein generating a feedback signal having Cartesian components derived from the interference-compensated signal comprises demodulating an output of a transimpedance operational amplifier as a function of the frequency of an interference signal input to the transimpedance operational amplifier.

8. The method of claim 1, wherein generating the feedback signal comprises demodulating the interference-compensated signal as a function of the narrowband interference signal frequency.

9. The method of claim 1, wherein removing Cartesian components associated with the signal of interest from the feedback signal comprises low-pass filtering the feedback signal to reject the Cartesian components associated with the signal of interest.

10. The method of claim 1, wherein the narrowband interference signal estimate is generated by:

modulating the feedback signal after removal of the Cartesian components associated with the signal of interest; and

amplifying the modulated feedback signal as the narrowband interference signal estimate.

11. A narrowband interference cancellation circuit, comprising:

a signal combiner configured to destructively combine a composite signal including a narrowband interference signal and a signal of interest with an estimate of the narrowband interference signal to generate an interference-compensated signal;

a feedback path configured to generate a feedback signal having Cartesian components derived from the interference-compensated signal;

a filter configured to remove Cartesian components associated with the signal of interest from the feedback signal; and

a signal estimator configured to generate the narrowband interference signal estimate based on the feedback signal after removal of the Cartesian components associated with the signal of interest.

12. The circuit of claim 11, wherein the signal combiner is configured to sum the composite signal and an opposite of the narrowband interference signal estimate.

13. The circuit of claim 11, wherein the signal combiner is configured to destructively combine a WCDMA baseband signal including a GSM narrowband interference signal and a WCDMA signal of interest with an estimate of the GSM narrowband interference signal.

14. The circuit of claim 13, wherein the feedback path is configured to demodulate the interference-compensated signal as a function of the GSM narrowband interference signal frequency.

15. The circuit of claim 11, wherein the signal combiner is configured to destructively combine a digital-to-analog converter output signal including a narrowband interference image and a signal of interest with an estimate of the narrowband interference image.

16. The circuit of claim 15, wherein the feedback path is configured to demodulate the interference-compensated signal as a function of the narrowband interference image frequency.

17. The circuit of claim 11, wherein the feedback path is configured to demodulate an output of a transimpedance operational amplifier coupled to the narrowband interference cancellation circuit as a function of the frequency of an interference signal input to the transimpedance operational amplifier.

18. The circuit of claim 11, wherein the feedback path is configured to demodulate the interference-compensated signal as a function of the narrowband interference signal frequency.

19. The circuit of claim 11, wherein the filter is configured to low-pass filter the feedback signal to reject the Cartesian components associated with the signal of interest.

20. The circuit of claim 11, wherein the signal estimator is configured to modulate the feedback signal after removal of the Cartesian components associated with the signal of interest and amplify the modulated feedback signal as the narrowband interference signal estimate.

21. A radio receiver including the circuit as claimed in claim 11.