SWITCHED, SIMULTANEOUS AND CASCADED INTERFERENCE CANCELLATION

• US 20160211882A1
• Filed: 01/20/2015
• Published: 07/21/2016
• Est. Priority Date: 01/20/2015
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Hwang, Insoo, Song, Bongyong, Nguyen, Cong
• Granted Patent: US 9,590,673 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: H04B 1/126 having multiple inputs, e.g. auxiliary antenna for receiving interfering signal aerials in general H01Q
• CPC Class Codes: H04B 1/406 with more than one transmission mode, e.g. analog and digital modes
• CPC Class Codes: H04B 1/525 with means for reducing leakage of transmitter signal into the receiver

Abstract

Aspects of the disclosure are directed to interference cancellation and wireless communication. A method of performing analog interference cancellation in a wireless communications device having a transmitter and a receiver includes receiving a reference signal representative of an interfering signal transmitted by the transmitter, selecting a first target interference type from one of a plurality of interference types affecting a an RF signal received by the receiver, configuring a first filter of an interference cancellation circuit using a coefficient computed based on the first target interference type, and cancelling interference in the RF signal using an output of the first filter. Coefficient computation may be performed in a switched manner between analog and digital domain, simultaneously in multiple domains, or in a cascaded manner that provides digital interference cancellation.

Claims

1. A method of performing interference cancellation in a wireless communications device having a transmitter and a receiver, the method comprising:

receiving a reference signal representative of an interfering signal transmitted by the transmitter;

responsive to the reference signal, selecting a first target interference type from one of a plurality of interference types affecting a radio frequency (RF) signal received by the receiver;

configuring a first filter of an interference cancellation circuit using a coefficient computed based on the first target interference type; and

cancelling interference in the RF signal using an output of the first filter.

2. The method of claim 1, wherein selecting the first target interference type comprises:

selecting fundamental frequency interference as the target interference type when interference in the fundamental frequency of the RF signal exceeds a predefined threshold power level; and

selecting out of band interference as the target interference type when interference in the fundamental frequency of the RF signal does not exceed the predefined threshold power level.

3. The method of claim 1, wherein the first target interference type includes interference at a fundamental frequency of the RF signal, and further comprising:

computing the coefficient in an analog domain.

4. The method of claim 1, wherein the first target interference type includes out of band interference, and further comprising:

computing the coefficient in a digital domain.

5. The method of claim 4, wherein computing the coefficient in the digital domain includes:

computing the coefficient from a baseband representation of the RF signal.

6. The method of claim 4, further comprising:

converting the coefficient to an analog coefficient; and

applying the analog coefficient to the interference cancellation circuit to cancel the interference in the RF signal.

7. The method of claim 1, wherein the first target interference type includes interference at a fundamental frequency of the RF signal, and further comprising:

providing the first filter an analog feedback signal representative of the RF signal,

wherein the output of the first filter is generated using the analog feedback signal.

8. The method of claim 1, wherein the first filter comprises a least-mean squares filter.

9. The method of claim 1, wherein configuring the first filter comprises:

closing one or more switches based on the first target interference type,

wherein each of the one or more switches controls provision of a respective type of feedback to the first filter.

10. The method of claim 9, wherein a first one of the one or more switches selects a source of feedback to the first filter.

11. The method of claim 9, wherein digital coefficients control the first filter when a second one of the one or more switches is closed.

12. The method of claim 1, wherein configuring the first filter comprises:

providing the first filter a baseband feedback signal generated from the coefficient.

13. The method of claim 1, further comprising:

selecting a second target interference type from one of a plurality of interference types affecting the RF signal received by the receiver;

configuring a second filter of the interference cancellation circuit using a coefficient computed based on the second target interference type; and

cancelling interference in the RF signal using an output of the second filter while cancelling interference in the RF signal using the output of the first filter.

14. The method of claim 1, further comprising:

receiving a baseband transmission signal from the transmitter; and

cancelling interference in a baseband representation of the RF signal using the baseband transmission signal.

15. The method of claim 14, wherein the baseband transmission signal comprises a digital signal.

16. An interference cancelling circuit that is coupled to a radio frequency (RF) receiver and comprises:

a first interference circuit configured to cancel interference at a fundamental frequency in an RF signal received by the RF receiver;

a second interference circuit configured to cancel out-of-band interference associated with the RF signal;

wherein activation of the first interference circuit and the second interference circuit is controlled based on power level of interference affecting the RF signal.

17. The interference cancelling circuit of claim 16, further comprising:

a first switch configured to control the first interference circuit by providing analog feedback to the first interference circuit when the first switch is activated, wherein operation of the first interference circuit is disabled when the first switch is deactivated; and

a second switch configured to control the second interference circuit by steering the second interference circuit using digital coefficients when the second switch is activated, wherein operation of the second interference circuit is disabled when the second switch is deactivated.

18. The interference cancelling circuit of claim 17, wherein:

the first switch is activated when interference in the fundamental frequency of the RF signal exceeds a predefined threshold power level; and

the second switch is activated when interference in the fundamental frequency of the RF signal does not exceed the predefined threshold power level.

19. The interference cancelling circuit of claim 17, wherein an analog feedback signal provided by the receiver is provided to the first interference circuit when the first switch is activated.

20. The interference cancelling circuit of claim 17, further comprising:

a controller adapted to generate digital coefficients from a baseband representation of the RF signal, wherein the digital coefficients steer the second interference circuit when the second switch is activated.

21. The interference cancelling circuit of claim 17, further comprising:

a control circuit configured to operate the first switch and the second switch based on an estimation of noise power in the fundamental frequency of the RF signal obtained using a reference signal representative of an interfering signal transmitted by a transmitter coupled to the interference cancelling circuit.

22. The interference cancelling circuit of claim 17, further comprising:

a control circuit configured to operate the first switch and the second switch based on an estimation of noise power in the fundamental frequency of the RF signal obtained using a reference signal representative of an interfering signal transmitted by a transmitter coupled to the interference cancelling circuit.

23. The interference cancelling circuit of claim 17, further comprising:

a controller adapted to generate digital coefficients from a baseband representation of the RF signal, wherein the digital coefficients steer the second interference circuit when the second switch is activated.

24. The interference cancelling circuit of claim 16, further comprising:

a digital cancellation circuit configured to cancel interference in a baseband signal derived from the RF signal using a digital representation of an interfering signal transmitted by a transmitter coupled to the interference cancelling circuit.

25. The interference cancelling circuit of claim 24, wherein the baseband signal comprises a signal that has been processed by the first interference circuit or the second interference circuit.

26. An interference cancelling circuit that is coupled to a radio frequency (RF) receiver and comprises:

a first interference circuit configured to cancel interference at a fundamental frequency in an RF signal received by the RF receiver using analog feedback;

a second interference circuit configured to cancel out-of-band interference associated with the RF signal using digital feedback.

27. The interference cancelling circuit of claim 26, wherein the analog feedback comprises a feedback signal provided by the receiver.

28. The interference cancelling circuit of claim 26, further comprising:

a controller adapted to generate first digital coefficients and second digital coefficients from a baseband representation of the RF signal,

wherein the first digital coefficients steer a filter in the first interference circuit, and

wherein the second digital coefficients steer a filter in the second interference circuit.

29. The interference cancelling circuit of claim 26, further comprising:

a control circuit configured to control the first interference circuit or the second interference circuit based on an estimation of noise power in the fundamental frequency of the RF signal obtained using a reference signal representative of an interfering signal transmitted by a transmitter coupled to the interference cancelling circuit.

30. The interference cancelling circuit of claim 26, further comprising:

a digital cancellation circuit configured to cancel interference in a baseband signal derived from the RF signal using a digital representation of an interfering signal transmitted by a transmitter coupled to the interference cancelling circuit.