METHOD AND SYSTEM FOR MITIGATING THE EFFECTS OF A TRANSMITTED BLOCKER AND DISTORTIONS THEREFROM IN A RADIO RECEIVER

• US 20140140250A1
• Filed: 11/14/2013
• Published: 05/22/2014
• Est. Priority Date: 11/14/2012
• Status: Active Grant

• Current Assignee: Andrew Joo Kim, Stephane Laurent-Michel, Stephen Jantzi
• Original Assignee: Spectra7 Microsystems Ltd.
• Inventors: Kim, Andrew Joo, Jantzi, Stephen, Laurent-Michel, Stephane
• Granted Patent: US 9,755,691 B2
• Time in Patent Office: Days
• US Class Current: 370/278
• CPC Class Codes: H04B 1/1027 assessing signal quality or detecting noise/interference for the received signal
• CPC Class Codes: H04B 1/525 with means for reducing leakage of transmitter signal into the receiver
• CPC Class Codes: H04L 25/061 providing hard decisions only; arrangements for tracking or suppressing unwanted low frequency components, e.g. removal of dc offset removal of dc offset in coupling arrangements H04L25/029, H04L25/0296
• CPC Class Codes: H04L 25/062 Setting decision thresholds using feedforward techniques only
• CPC Class Codes: H04L 27/2647 Arrangements specific to the receiver only equalisation H04L27/01
• CPC Class Codes: H04L 7/033 using the transitions of the received signal to control the phase of the synchronising-signal-generating means, e.g. using a phase-locked loop

Abstract

A radio receiver processing path has a mixer with active interference/blocker cancellation to reduce the intensity of leaked and undesired signals by using a replica of the transmitted signal, emulating the phase and attenuation through the leakage path and subtracting the emulated signal within the mixer. Intermodulation distortions are predicted through the use of nonlinear modeling in the digital baseband between the baseband transmitter and baseband receiver and subsequently subtracted from the received signal. The nonlinear basis functions are combined to model the composite nonlinearity in the signal path based on digital baseband transmitted data. The modeled nonlinearity is subtracted from the received signal, and the result is observed and used to guide the nonlinear modeling parameters using self-contained control loops.

Claims

1. A method for reducing noise included in a receive path of a radio system, comprising the following steps:

forwarding a transmit signal from a transmit path of the radio to a nonlinear function generator;

generating a first nonlinear basis function signal from the forwarded transmit signal;

forwarding the first nonlinear basis function signal to the receive path; and

canceling at least a portion of noise in a receive path signal using the first nonlinear basis function signal to obtain a reduced-distortion receive path signal.

2. The method of claim 1, wherein the transmit signal and the receive signal are at an intermediate frequency.

3. The method of claim 1, wherein the transmit signal and the receive signal are in a baseband.

4. The method of claim 1, further comprising scaling the first nonlinear basis function signal prior to canceling the portion of the noise in the receive path signal.

5. The method of claim 4, further comprising adaptively controlling a scale factor for scaling the first nonlinear basis function signal, wherein adaptively controlling the scale factor comprises:

comparing the first nonlinear basis function signal with the reduced-distortion receive path signal;

in response to the comparison indicating that the current scaling is too small, increasing the scaling; and

in response to the comparison indicating that the current scaling is too large, decreasing the scaling.

6. The method of claim 1, further comprising generating an additional nonlinear basis function signal from the forwarded transmit signal, and wherein canceling the noise in the receive path signal comprises using the additional nonlinear basis function signal in combination with the first nonlinear basis function signal to obtain the reduced-distortion receive path signal.

7. The method of claim 1, wherein the first nonlinear basis function includes a Volterra series expansion of the transmit signal.

8. The method of claim 1, wherein the first nonlinear basis function includes a Legendre polynomial expansion of the transmit signal.

9. The method of claim 1, wherein canceling is performed in the analog domain.

10. The method of claim 1, wherein canceling is performed in the digital domain.

11. The method of claim 1, wherein the transmit signal includes a signal from an output of a power amplifier, and forwarding the transmit signal comprises down-converting the transmit signal.

12. A method for reducing leakage noise occurring in a receive path of a radio system, the method comprising the following steps:

forwarding a transmit signal from a transmit path of the radio to a scaler;

scaling the transmit signal using the scaler;

forwarding the scaled transmit signal to a canceling down-converting mixer in the receive path; and

canceling at least a portion of leakage noise included in a receive path signal with the canceling down-converting mixer using the scaled transmit signal.

13. The method of claim 12, wherein canceling comprises up-converting the scaled transmit signal to an RF frequency.

14. The method of claim 12, wherein the transmit signal includes a digital signal, the method further comprising converting the transmit signal from digital to analog prior to canceling with the scaled transmit signal.

15. The method of claim 12, wherein the canceling down-converting mixer comprises a bandpass mixer.

16. The method of claim 12, wherein the transmit signal includes a signal from an output of a power amplifier, and wherein forwarding the transmit signal further comprises down-converting the transmit signal.

17. A radio, comprising:

a digital processor including an input coupled with an output of a baseband transmit module;

a digital-to-analog converter including an input coupled with an output of the digital processor; and

a canceling down-converting mixer in a receive path including an input coupled with an output of the digital-to-analog converter.

18. A radio, comprising:

a first down-converting mixer including a first input coupled with a location in a transmit path carrying an RF transmit signal, a second input coupled with a local oscillator, and an output; and

a scaler including an input coupled with an output of the first down-converting mixer and an output coupled with an input of a canceling down-converting mixer in a receive path.

19. A radio, comprising:

a first down-converting mixer including a first input coupled with a location in a transmit path carrying an RF transmit signal and a second input coupled with a local oscillator;

an analog-to-digital converter including an input coupled with an output of the first down-converting mixer;

a digital processor including an input coupled with an output of the analog-to-digital converter;

a digital-to-analog converter including an input coupled with an output of the digital processor; and

a canceling down-converting mixer in a receive path including an input coupled with an output of the digital-to-analog converter.

20. A distortion cancellation module, comprising:

a corrupted receive signal input;

a transmit signal input;

a restored signal output;

a nonlinear basis function generator including an input coupled with the transmit signal input;

a first scaler including an input coupled with a first output of the nonlinear basis function generator;

a summer including a first input coupled with the output of the first scaler, a second input coupled with the corrupted receive signal input, and an output coupled with the restored signal output; and

a first adaptive control unit including a first input coupled with the restored signal output and a second input coupled the first output of the nonlinear basis function generator;

wherein the first adaptive control unit is adapted to control a scale factor of the first scaler.