NON-LINEAR ADAPTIVE SCHEME FOR CANCELLATION OF TRANSMIT OUT OF BAND EMISSIONS

• US 20120140860A1
• Filed: 12/01/2011
• Published: 06/07/2012
• Est. Priority Date: 12/01/2010
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Rimini, Roberto, Burke, Joseph Patrick, Omer, Mohammad, Heidmann, Peter D.
• Granted Patent: US 8,804,871 B2
• Time in Patent Office: Days
• US Class Current: 375/350
• CPC Class Codes: H04B 1/525 with means for reducing leakage of transmitter signal into the receiver
• CPC Class Codes: H04J 11/004 using regenerative subtractive interference cancellation
• CPC Class Codes: H04L 5/0023 Time-frequency-space

Abstract

A method and apparatus for a non-linear adaptive scheme for transmit out of band emission cancellation is provided. Embodiments disclosed herein provide a method for removing unwanted transmitter emissions from a composite received signal. The method performs the steps of: extracting the I and Q samples from a modulator output; inputting the I and Q samples to a non-linear filter; applying weights to the non-linear filter outputs, combining the non-linear filter outputs to generate a broadband emission estimate; selecting a portion of a transmit emission in a desired portion of a receive band; subtracting an output of the non-linear filter from a composite signal; and feeding back a residual error to the non-linear filter; adapting the non-linear filter iteratively.

Claims

1. A method for removing unwanted transmitter emissions from a composite received signal, comprising:

extracting I and Q samples from a modulator output;

inputting the I and Q samples to a non-linear filter;

applying weights to the non-linear filter outputs;

combining the non-linear filter outputs to generate a broadband emission estimate;

selecting a portion of a transmit emission in a desired portion of a receive band;

subtracting an output of a frequency selection block from a composite signal; and

adapting the non-linear filter iteratively.

2. The method of claim 1, wherein the non-linear filter iterative adaptation uses an appropriate representation of selected Volterra kernels.

3. The method of claim 1, wherein the adaptation of the non-linear filter is based on a mean square error calculation and minimizes the means square error.

4. The method of claim 1, wherein the composite signal is in a receive frequency band.

5. An apparatus for removing unwanted transmitter emissions from a composite received signal, comprising:

a first processor for sampling I and Q samples from a modulator;

a non-linear filter based on a linear combination of selected Volterra kernels through weights derived by mean square error calculations, that receives the I and Q transmitter samples as input signals;

a second processor for subtracting an output of the non-linear filter from a composite signal; and

a third processor for iteratively adapting the non-linear filter based on a residual error fed back to the non-linear filter.

6. The apparatus of claim 5, further comprising a digital frequency shifter and digital low-pass filter inserted at the output of the non-linear filter.

7. The apparatus of claim 5, wherein the Volterra kernels include at least one memory element.

8. An apparatus for removing unwanted transmitter emissions from a composite received signal, comprising:

means for extracting I and Q samples from a modulator output;

means for inputting the I and Q samples to a non-linear filter;

means for applying weights to the non-linear filter outputs;

means for combining the non-linear filter outputs to generate a broadband emission estimate;

means for selecting a portion of a transmit emission in a desired portion of a receive band;

means for subtracting an output of a frequency selection block from a composite signal;

means for feeding back the residual error;

means for adapting the non-linear filter iteratively based on the minimization of Mean Square Error power.

9. The apparatus of claim 8, wherein the means for adapting the non-linear filter uses an appropriate representation of selected Volterra kernels.

10. The apparatus of claim 8, wherein the means for adapting the non-linear filter is based on a mean square error calculation and mean square error minimization.

11. The apparatus of claim 8, wherein the composite signal operated on by the means for subtracting an output of the non-linear filter from a composite signal is in a receive frequency band.

12. A non-transitory computer-readable medium comprising instructions, which when executed by a processor cause the processor to perform the following operations:

extract I and Q samples from a modulator output;

input the I and Q samples to a non-linear filter;

apply weights to the non-linear filter output;

combine the non-linear filter outputs to generate a broadband emission estimate;

select a portion of a transmit emission

subtract an output of the non-linear filter from a composite signal; and

adapt the non-linear filter iteratively.

13. The non-transitory computer-readable medium of claim 12, wherein the non-linear filter iterative adaptation uses an appropriate representation of selected Volterra kernels.

14. The non-transitory computer-readable medium of claim 12, wherein the adapting of the non-linear filter is based on a mean square error calculation and minimizes the mean square error.

15. The non-transitory computer-readable medium of claim 12, wherein the composited signal is in a receive frequency band.