PILOT-BASED ANALOG ACTIVE INTERFERENCE CANCELLER

• US 20160344432A1
• Filed: 05/22/2015
• Published: 11/24/2016
• Est. Priority Date: 05/22/2015
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Hwang, Insoo, Nguyen, Cong, Song, Bongyong
• Granted Patent: US 9,800,287 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• 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. A method for performing interference cancellation in a wireless communications device having a transmitter, a receiver, a coefficient controller, an analog interference cancellation (AIC) circuit and a receive local oscillator (LO) includes utilizing a receive local oscillator (LO) to generate a transmit pilot; injecting the transmit pilot into a transmit chain for transmission; utilizing a receiver to receive a signal, wherein the signal includes the transmit pilot and an interference signal; and determining a set of coefficients for the interference cancellation based on an output signal from the receiver.

Claims

1. A method for interference cancellation, comprising:

utilizing a receive local oscillator (LO) located in a receive chain to generate a transmit pilot;

injecting the transmit pilot into a transmit chain for transmission;

utilizing a receiver to receive a signal, wherein the signal includes the transmit pilot and an interference signal; and

determining a set of coefficients for the interference cancellation based on an output signal from the receiver.

2. The method of claim 1, further comprising:

applying the set of coefficients to an adaptive filter coupled to the receiver; and

cancelling interference associated with the interference signal utilizing the adaptive filter with the applied set of coefficients.

3. The method of claim 2, further comprising utilizing a coefficient controller for determining the set of coefficients to be applied to the adaptive filter.

4. The method of claim 3, wherein the coefficient controller utilizes a least mean square (LMS) error criterion for determining the set of coefficients to be applied to the adaptive filter.

5. The method of claim 4, wherein the adaptive filter is a single tap minimum mean square error (MMSE) filter.

6. The method of claim 1, further comprising:

comparing a desired receive signal against the interference signal;

determining if the desired receive signal includes a first signal level greater than a second signal level of the interference signal minus a threshold; and

enabling a path for injecting the transmit pilot into the transmit chain for transmission if the desired receive signal includes the first signal level that is greater than the second signal level of the interference signal minus the threshold.

7. The method of claim 6, wherein the threshold is between 8 dB and 12 dB.

8. The method of claim 6, further comprising enabling the path for injecting the transmit pilot utilizing a switch.

9. The method of claim 1, further comprising setting the receive local oscillator (LO) to a transmit frequency of an offending transmitter.

10. The method of claim 9, wherein the offending transmitter operates at a Long Term Evolution (LTE) band and the receiver operates at a WiFi band.

11. The method of claim 1, further comprising setting the receive local oscillator (LO) to a receive frequency of the receiver.

12. The method of claim 1, wherein the receiver and an offending transmitter associated with the transmit chain share a same antenna.

13. The method of claim 1, further comprising utilizing the receive local oscillator (LO) to downconvert the signal received by the receiver.

14. An apparatus for interference cancellation, comprising:

a receive local oscillator (LO) located in a receive chain for generating a transmit pilot;

a splitter coupled to the receive LO for injecting the transmit pilot into a transmit chain for transmission;

a receiver for receiving a signal, wherein the signal includes the transmit pilot and an interference signal; and

a first processor coupled to the receiver for determining a set of coefficients for the interference cancellation based on an output signal from the receiver.

15. The apparatus of claim 14, further comprising:

a coefficient control logic for applying the set of coefficients to an adaptive filter coupled to the receiver; and

a subtractor for cancelling interference associated with the interference signal with a filtered control signal outputted from the adaptive filter with the applied set of coefficients.

16. The apparatus of claim 15, further comprising a coefficient computation unit for determining the set of coefficients to be applied to the adaptive filter.

17. The apparatus of claim 16, wherein the coefficient computation unit utilizes a least mean square (LMS) error criterion for determining the set of coefficients to be applied to the adaptive filter.

18. The apparatus of claim 17, wherein the adaptive filter is a single tap minimum mean square error (MMSE) filter.

19. The apparatus of claim 14, further comprising:

a second processor coupled to the receiver for comparing a desired receive signal against the interference signal, and for determining if the desired receive signal includes a first signal level greater than a second signal level of the interference signal minus a threshold; and

a switch coupled to the processor for enabling a path for injecting the transmit pilot into the transmit chain for transmission if the desired receive signal includes the first signal level that is greater than the second signal level of the interference signal minus the threshold.

20. The apparatus of claim 19, wherein the threshold is between 8 dB to 12 dB.

21. The apparatus of claim 19, where the second processor is the same as the first processor.

22. The apparatus of claim 14, further comprising a second processor for setting the receive local oscillator to a transmit frequency of an offending transmitter.

23. The apparatus of claim 22, wherein the offending transmitter operates at a Long Term Evolution (LTE) band and the receiver operates at a WiFi band.

24. The apparatus of claim 14, further comprising a second processor for setting the receive local oscillator to a receive frequency of the receiver.

25. The apparatus of claim 14, wherein the receiver and an offending transmitter associated with the transmit chain share a same antenna.

26. The apparatus of claim 14, wherein the receive local oscillator (LO) is configured to downconvert the signal received by the receiver.

27. An apparatus for interference cancellation, comprising:

at least one processor;

a memory for storing a first set of coefficients for initialization of an adaptive filter, the memory coupled to the at least one processor;

a receiver coupled to the at least one processor for receiving a signal, wherein the signal includes a transmit pilot and an interference signal;

means for utilizing a receive local oscillator (LO) to generate the transmit pilot, wherein the receive LO is located in a receive chain;

means for injecting the transmit pilot into a transmit chain for transmission; and

means for determining a second set of coefficients for the interference cancellation based on an output signal from the receiver.

28. The apparatus of claim 27, further comprising:

means for applying the second set of coefficients to the adaptive filter, wherein the adaptive filter is coupled to the receiver; and

means for cancelling interference associated with the interference signal utilizing the adaptive filter with the applied second set of coefficients.

29. A non-transitory computer-readable storage medium storing computer executable code, operable on a device comprising at least one processor;

a memory for storing a first set of coefficients for initialization of an adaptive filter, the memory coupled to the at least one processor;

a receiver coupled to the at least one processor, wherein the receiver is configured to receive a signal; and

the computer executable code comprising;

instructions for causing the at least one processor to utilize a receive local oscillator (LO) located in a receive chain to generate a transmit pilot;

instructions for causing the at least one processor to inject the transmit pilot into a transmit chain for transmission; and

instructions for causing the at least one processor to determine a second set of coefficients for the interference cancellation based on an output signal from the receiver, wherein the signal received by the receiver includes the transmit pilot and an interference signal.

30. The non-transitory computer-readable storage medium of claim 29, wherein the computer executable code further comprising:

instructions for causing the at least one processor to apply the second set of coefficients to the adaptive filter, wherein the adaptive filter is coupled to the receiver; and

instructions for causing the at least one processor to cancel interference associated with the interference signal utilizing the adaptive filter with the applied second set of coefficients.