JOINT LINEAR AND NON-LINEAR CANCELLATION OF TRANSMIT SELF-JAMMING INTERFERENCE

• US 20130044791A1
• Filed: 08/16/2012
• Published: 02/21/2013
• Est. Priority Date: 08/18/2011
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Rimini, Roberto, Heidmann, Peter D., Gudem, Prasad S., Verma, Sumit, Burke, Joseph
• Granted Patent: US 8,767,869 B2
• Time in Patent Office: Days
• US Class Current: 375/219
• CPC Class Codes: H04B 1/109 by improving strong signal performance of the receiver when strong unwanted signals are present at the receiver input
• CPC Class Codes: H04B 1/30 for homodyne or synchrodyne receivers demodulator circuits H03D1/22
• CPC Class Codes: H04B 1/525 with means for reducing leakage of transmitter signal into the receiver

Abstract

Certain aspects of the present disclosure propose an adaptive joint linear and non-linear digital filter that can adaptively estimate and reconstruct cascaded effects of linear and non-linear self-jamming distortions introduced by non-linearities in the transmit and/or receive chains. The proposed digital filter may be used to cancel second-order inter-modulation distortion (IM2) generated in the receive chain and/or harmonic distortion generated in the transmit chain, as well as other distortions introduced by the transmit/and or receive chains.

Claims

1. A method, comprising:

generating a signal to be transmitted on a first frequency band;

transmitting the generated signal on the first frequency band;

computing an estimated distorted version of the generated signal by applying an adaptive joint linear and non-linear digital filter to the generated signal at baseband;

receiving a composite signal on at least a second frequency band, the composite signal comprising a desired signal and self-jamming interference, wherein the self-jamming interference is caused by a cascaded effect of at least one of non-linear or linear distortions introduced by at least one of transmit or receive chain non-idealities; and

subtracting the estimated distorted version of the generated signal from the composite signal to remove the self-jamming interference.

2. The method of claim 1, wherein computing the estimated distorted version of the generated signal comprises:

applying a Volterra based filter to the generated signal at baseband, wherein the Volterra based filter comprises linear operators, non-linear operators, and delay elements.

3. The method of claim 2, wherein the Volterra based filter estimates second-order inter-modulation (IM2) distortion.

4. The method of claim 2, wherein the Volterra based filter estimates 3^rd harmonic distortion (H3D).

5. The method of claim 2, wherein applying the Volterra based filter comprise:

applying polynomial generators to the generated signal at baseband to generate one or more Volterra states;

applying one or more weights to the generated one or more Volterra states; and

generating a sum of the one or more weighted Volterra states.

6. The method of claim 5, wherein applying the polynomial generators to the generated signal at baseband comprises:

applying delay to the generated signal at baseband or to the Volterra states.

7. The method of claim 5, wherein applying the polynomial generators to the generated signal at baseband comprises:

applying a generic p-th order polynomial expansion to the generated signal at baseband;

generating at least one of p-th order inter-modulation (IMp) distortion or p-th order harmonic distortion (HpD).

8. The method of claim 5, further comprising:

generating the one or more weights by minimizing a cost function.

9. The method of claim 8, wherein the cost function is minimized by utilizing a least mean square (LMS), a recursive least squares (RLS) algorithm, least squares (LS) or a direct matrix inversion method, or other mean squared error methods.

10. The method of claim 1, wherein the self-jamming interference is caused by a plurality of transmitter sources that are simultaneously active in an apparatus, and the self-jamming interference comprises a p-order inter-modulation distortion where p>

1 and m-order harmonic distortion where m>

1.

11. The method of claim 1, wherein the transmitted and received signals are wireless signals.

12. The method of claim 11, wherein the transmitted and received signals are from different systems that co-exist in the same apparatus.

13. The method of claim 1, wherein the transmitted and received signals are wired signals.

14. The method of claim 13, wherein the transmitted and received signals are from different systems that co-exist in the same apparatus.

15. The method of claim 1, wherein multiple signals transmitted simultaneously by different co-located transmitters or a multi-carrier transceiver inter-modulate reciprocally due to non-linear radio frequency (RF) effects thus producing cross-jamming interference in a given receiver band.

16. The method of claim 15, wherein the estimated distorted version of the generated signal is computed by applying the adaptive joint linear and non-linear digital filter to the multiple transmitted signals at baseband.

17. The method of claim 15, wherein an estimated joint multiple receiver distortion is computed by applying the adaptive joint linear and non-linear digital filter to the multiple transmitted signals at baseband.

18. The method of claim 1, wherein the adaptive digital filter comprises linear coefficients and delay to estimate purely linear distortion.

19. The method of claim 1, wherein the adaptive digital filter comprises a frequency rotator to compensate frequency offset between the estimated distorted version of the generated signal and the self-jamming interference present in the composite signal.

20. An apparatus, comprising:

means for generating a signal to be transmitted on a first frequency band;

means for transmitting the generated signal on the first frequency band;

means for computing an estimated distorted version of the generated signal by applying an adaptive joint linear and non-linear digital filter to the generated signal at baseband;

means for receiving a composite signal on at least a second frequency band, the composite signal comprising a desired signal and self-jamming interference, wherein the self-jamming interference is caused by a cascaded effect of at least one of non-linear or linear distortions introduced by at least one of transmit or receive chain non-idealities; and

means for subtracting the estimated distorted version of the generated signal from the composite signal to remove the self-jamming interference.

21. The apparatus of claim 20, wherein the means for computing the estimated distorted version of the generated signal comprises:

means for applying a Volterra based filter to the generated signal at baseband, wherein the Volterra based filter comprises linear operators, non-linear operators, and delay elements.

22. The apparatus of claim 21, wherein the Volterra based filter estimates second-order inter-modulation (IM2) distortion.

23. The apparatus of claim 21, wherein the Volterra based filter estimates 3^rd harmonic distortion (H3D).

24. The apparatus of claim 21, wherein the means for applying the Volterra based filter comprise:

means for applying polynomial generators to the generated signal at baseband to generate one or more Volterra states;

means for applying one or more weights to the generated one or more Volterra states; and

means for generating a sum of the one or more weighted Volterra states.

25. The apparatus of claim 24, wherein the means for applying the polynomial generators to the generated signal at baseband comprises:

means for applying delay to the generated signal at baseband or to the Volterra states.

26. The apparatus of claim 24, wherein the means for applying the polynomial generators to the generated signal at baseband comprises:

means for applying a generic p-th order polynomial expansion to the generated signal at baseband;

means for generating at least one of p-th order inter-modulation (IMp) distortion or p-th order harmonic distortion (HpD).

27. The apparatus of claim 24, further comprising:

means for generating the one or more weights by minimizing a cost function.

28. The apparatus of claim 27, wherein the cost function is minimized by utilizing a least mean square (LMS), a recursive least squares (RLS) algorithm, least squares (LS) or a direct matrix inversion method, or other mean squared error methods.

29. The apparatus of claim 20, wherein the self-jamming interference is caused by a plurality of transmitter sources that are simultaneously active in an apparatus, and the self-jamming interference comprises a p-order inter-modulation distortion where p>

1 and m-order harmonic distortion where m>

1.

30. The apparatus of claim 20, wherein the transmitted and received signals are wireless signals.

31. The apparatus of claim 30, wherein the transmitted and received signals are from different systems that co-exist in the same apparatus.

32. The apparatus of claim 20, wherein the transmitted and received signals are wired signals.

33. The apparatus of claim 32, wherein the transmitted and received signals are from different systems that co-exist in the same apparatus.

34. The apparatus of claim 20, wherein multiple signals transmitted simultaneously by different co-located transmitters or a multi-carrier transceiver inter-modulate reciprocally due to non-linear radio frequency (RF) effects thus producing cross-jamming interference in a given receiver band.

35. The apparatus of claim 34, wherein the estimated distorted version of the generated signal is computed by applying the adaptive joint linear and non-linear digital filter to the multiple transmitted signals at baseband.

36. The apparatus of claim 34, wherein an estimated joint multiple receiver distortion is computed by applying the adaptive joint linear and non-linear digital filter to the multiple transmitted signals at baseband.

37. The apparatus of claim 20, wherein the adaptive digital filter comprises linear coefficients and delay to estimate purely linear distortion.

38. The apparatus of claim 20, wherein the adaptive digital filter comprises a frequency rotator to compensate frequency offset between the estimated distorted version of the generated signal and the self-jamming interference present in the composite signal.

39. A computer-program product, comprising a non-transitory computer readable medium having instructions stored thereon, the instructions being executable by one or more processors and the instructions comprising:

instructions for generating a signal to be transmitted on a first frequency band;

instructions for transmitting the generated signal on the first frequency band;

instructions for computing an estimated distorted version of the generated signal by applying an adaptive joint linear and non-linear digital filter to the generated signal at baseband;

instructions for receiving a composite signal on at least a second frequency band, the composite signal comprising a desired signal and self-jamming interference, wherein the self-jamming interference is caused by a cascaded effect of at least one of non-linear or linear distortions introduced by at least one of transmit or receive chain non-idealities; and

instructions for subtracting the estimated distorted version of the generated signal from the composite signal to remove the self-jamming interference.

40. An apparatus, comprising:

at least one processor configured to;

generate a signal to be transmitted on a first frequency band,

transmit the generated signal on the first frequency band,

compute an estimated distorted version of the generated signal by applying an adaptive joint linear and non-linear digital filter to the generated signal at baseband,

receive a composite signal on at least a second frequency band, the composite signal comprising a desired signal and self-jamming interference, wherein the self-jamming interference is caused by a cascaded effect of at least one of non-linear or linear distortions introduced by at least one of transmit or receive chain non-idealities, and

subtract the estimated distorted version of the generated signal from the composite signal to remove the self-jamming interference; and

a memory coupled to the at least one processor.