Systems and methods for adaptively-tuned digital self-interference cancellation

• US 9,742,593 B2
• Filed: 11/28/2016
• Issued: 08/22/2017
• Est. Priority Date: 12/16/2015
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Kumu Networks, Inc.
• Inventors: Moorti, Rajendra Tushar, Choi, Jung-Il, Jain, Mayank
• Primary Examiner(s): LAM, KENNETH T
• Application Number:
  US15/362,289
• Publication Number:
  US 20170180160A1
• Time in Patent Office: 267 Days
• CPC Class Codes: H04B 1/525 with means for reducing leakage of transmitter signal into the receiver
• CPC Class Codes: H04B 1/56 with provision for simultaneous communication in two directions
• CPC Class Codes: H04L 25/0204 of multiple channels
• CPC Class Codes: H04L 25/03006 Arrangements for removing intersymbol interference
• CPC Class Codes: H04L 25/0328 with interference cancellation circuitry adaptations for interference cancellation within a sequence estimator H04L25/03305; interference related aspects of direct sequence spread spectrum H04B1/7097; interference related aspects of frequency hopping spread spectrum H04B1/715; see also H04B1/10
• CPC Class Codes: H04L 27/2651 Modification of fast Fourier transform [FFT] or discrete Fourier transform [DFT] demodulators for performance improvement
• CPC Class Codes: H04L 47/29 using a combination of thresholds
• CPC Class Codes: H04L 5/14 Two-way operation using the same type of signal, i.e. duplex
• CPC Class Codes: H04L 5/1461 Suppression of signals in the return path, i.e. bidirectional control circuits

Abstract

A method for adaptively-tuned digital self-interference cancellation comprises receiving a digital transmit signal; receiving a transform configuration; generating a set of signal components from the digital transmit signal; transforming the set of signal components into a digital self-interference cancellation signal according to the transform configuration; combining the digital self-interference cancellation signal with a receive signal to form a digital residue signal; detecting a trigger; in response to detecting the trigger: computing a ratio of the digital residue signal to the digital transmit signal; converting the ratio to the frequency-domain to form a frequency-domain-converted ratio; computing a frequency-domain self-interference channel between the transmitter and the receiver based on the frequency-domain-converted ratio; computing an inverse discrete Fourier transform matrix based on a portion of the discrete Fourier transform matrix; converting the frequency-domain self-interference channel to form a time-domain self-interference channel; and updating the transform configuration based on the time-domain self-interference channel.

Claims

1. A method for adaptively-tuned digital self-interference cancellation comprising:

at a digital self-interference canceller of a communication system, receiving a digital transmit signal of a transmitter of the communication system;

receiving a transform configuration of the digital self-interference canceller;

generating a set of signal components from the digital transmit signal;

transforming the set of signal components into a digital self-interference cancellation signal according to the transform configuration;

combining the digital self-interference cancellation signal with a receive signal of a receiver of the communication system to form a digital residue signal;

detecting a trigger; and

in response to detecting the trigger;

transforming the digital residue signal and the digital transmit signal into a frequency domain by way of a discrete Fourier transform matrix;

computing a frequency-domain-converted ratio of the digital residue signal to the digital transmit signal;

computing a frequency-domain self-interference channel between the transmitter and the receiver based on the frequency-domain-converted ratio;

computing an inverse discrete Fourier transform matrix based on a portion of the discrete Fourier transform matrix;

wherein the portion is determined based on a desired size of the inverse discrete Fourier transform matrix;

converting the frequency-domain self-interference channel to a time-domain by way of the inverse discrete Fourier transform matrix to form a time-domain self-interference channel; and

updating the transform configuration based on the time-domain self-interference channel.

2. The method of claim 1, wherein detecting the trigger comprises detecting that a last update time has exceeded a time threshold.

3. The method of claim 1, wherein detecting the trigger comprises detecting that a receive signal power has exceeded a power threshold.

4. A method for adaptively-tuned digital self-interference cancellation comprising:

initiating tuning of an analog self-interference canceller;

at a digital self-interference canceller of a communication system, receiving a digital transmit signal from a transmitter of the communication system;

receiving a transform configuration of the digital self-interference canceller;

generating a digital self-interference cancellation signal from the digital transmit signal based on the transform configuration;

combining the digital self-interference cancellation signal with a receive signal to form a digital residue signal, wherein the receive signal is received from the analog self-interference canceller;

detecting a trigger;

pausing tuning of the analog self-interference canceller in response to detecting the trigger; and

updating the transform configuration based on the digital residue signal, wherein updating the transform configuration comprises updating the transform configuration in response to detecting the trigger.

5. The method of claim 4, wherein detecting the trigger comprises detecting that a last update time has exceeded a time threshold.

6. The method of claim 4, wherein detecting the trigger comprises detecting that a receive signal power has exceeded a power threshold.

7. The method of claim 4, wherein the transform configuration comprises a first of a set of static transform configurations, and wherein updating the transform configuration comprises selecting a static transform configuration of the set based on the digital residue signal.

8. The method of claim 4, wherein updating the transform configuration comprises computing a self-interference channel based on the digital residue signal and updating the transform configuration based on the computed self-interference channel.

9. The method of claim 8, wherein computing the self-interference channel comprises:

generating a composite residue signal from the digital residue signal and the digital transmit signal;

converting the composite residue signal to the frequency domain to form a frequency-domain-converted composite residue signal; and

computing the self-interference channel in the time domain based on the frequency-domain-converted composite residue signal to form a time-domain-converted self-interference channel;

wherein updating the transform configuration comprises updating the transform configuration based on the time-domain-converted self-interference channel.

10. The method of claim 9, wherein converting the composite residue signal to the frequency domain comprises converting the composite residue signal to the frequency domain using a discrete Fourier transform (DFT) matrix;

wherein computing the self-interference channel in the time domain comprises computing the self-interference channel in the frequency domain based on the frequency-domain-converted composite residue signal, and converting the computed self-interference channel to the time domain using an inverse discrete Fourier transform (IDFT) matrix.

11. The method of claim 10, further comprising decorrelating components of the computed self-interference channel prior to converting the computed self-interference channel to the time domain.

12. The method of claim 10, wherein the IDFT matrix is a reduced IDFT matrix, and further comprising computing the reduced IDFT matrix based on a portion of the DFT matrix.

13. The method of claim 12, wherein the portion of the DFT matrix is determined according to a desired set of frequency domain components of the DFT matrix.

14. The method of claim 8, further comprising generating a composite residue signal from the digital residue signal and the digital transmit signal;

wherein generating the composite residue signal comprises computing a ratio of the digital residue signal to the digital transmit signal.

15. The method of claim 14, wherein computing the ratio comprises computing a ratio of a first product and a second product;

wherein the first product is a product of a conjugate of the digital transmit signal and the digital residue signal;

wherein the second product is a product of the conjugate of the digital transmit signal and the digital transmit signal.

16. The method of claim 14, wherein computing the ratio comprises computing a time-averaged ratio;

wherein the time-averaged ratio is averaged over a first number of samples.

17. The method of claim 16, further comprising changing the first number of samples in response to a rate of change of the time-averaged ratio.

18. A method for adaptively-tuned digital self-interference cancellation comprising:

at a digital self-interference canceller, receiving a first digital transmit signal of a first transmitter and a second digital transmit signal of a second transmitter;

receiving an initial transform configuration of the digital self-interference canceller;

generating a digital self-interference cancellation signal from the first and second digital transmit signals based on the transform configuration;

combining the digital self-interference cancellation signal with a receive signal received from a receiver, resulting in a digital residue signal;

calculating the self-interference channel between the receiver and the first and second transmitters, wherein calculating comprises;

measuring the first digital transmit signal at a first time point and a second time point,

measuring the second digital transmit signal at the first and second time points,

measuring the digital residue signal at the first and the second time points, and

combining the first digital transmit signal measured at the first and second time points, the second digital transmit signal measured at the first and second time points, and the digital residue signal at the first and second time points to form the calculated self-interference channel; and

updating the transform configuration based on the digital residue signal and the calculated self-interference channel.

19. The method of claim 18, further comprising calculating a degree of correlation present between the first and second digital transmit signals, and calculating the self-interference channel only when the calculated degree of correlation is below a predetermined correlation threshold.

20. The method of claim 18, wherein the first digital transmit signal corresponds to a first subchannel;

wherein the second digital transmit signal corresponds to a second subchannel; and

further comprising;

determining a noise offset level of the self-interference channel,

normalizing the first digital transmit signal, the second digital transmit signal, and the digital residue signal according to the determined noise offset level prior to forming the calculated self-interference channel.

21. A method for adaptively-tuned digital self-interference cancellation comprising:

at a digital self-interference canceller of a communication system, receiving a digital transmit signal from a transmitter of the communication system;

receiving a transform configuration of the digital self-interference canceller;

generating a digital self-interference cancellation signal from the digital transmit signal based on the transform configuration;

combining the digital self-interference cancellation signal with a receive signal to form a digital residue signal; and

updating the transform configuration based on the digital residue signal;

wherein updating the transform configuration comprises computing a self-interference channel based on the digital residue signal and updating the transform configuration based on the computed self-interference channel;

wherein computing the self-interference channel comprises;

generating a composite residue signal from the digital residue signal and the digital transmit signal;

converting the composite residue signal to a frequency domain to form a frequency-domain-converted composite residue signal; and

computing the self-interference channel in a time domain based on the frequency-domain-converted composite residue signal to form a time-domain-converted self-interference channel;

wherein updating the transform configuration further comprises updating the transform configuration based on the time-domain-converted self-interference channel.

22. The method of claim 21, wherein converting the composite residue signal to the frequency domain comprises converting the composite residue signal to the frequency domain using a discrete Fourier transform (DFT) matrix;

wherein computing the self-interference channel in the time domain comprises computing the self-interference channel in the frequency domain based on the frequency-domain-converted composite residue signal, and converting the computed self-interference channel to the time domain using an inverse discrete Fourier transform (IDFT) matrix.

23. The method of claim 22, further comprising decorrelating components of the computed self-interference channel prior to converting the computed self-interference channel to the time domain.

24. The method of claim 22, wherein the IDFT matrix is a reduced IDFT matrix, and further comprising computing the reduced IDFT matrix based on a portion of the DFT matrix.

25. The method of claim 24, wherein the portion of the DFT matrix is determined according to a desired set of frequency domain components of the DFT matrix.

26. The method of claim 22, further comprising generating a composite residue signal from the digital residue signal and the digital transmit signal;

wherein generating the composite residue signal comprises computing a ratio of the digital residue signal to the digital transmit signal.

27. The method of claim 26, wherein computing the ratio comprises computing a ratio of a first product and a second product;

wherein the first product is a product of a conjugate of the digital transmit signal and the digital residue signal;

wherein the second product is a product of the conjugate of the digital transmit signal and the digital transmit signal.

28. The method of claim 26, wherein computing the ratio comprises computing a time-averaged ratio;

wherein the time-averaged ratio is averaged over a first number of samples.

29. The method of claim 28, further comprising changing the first number of samples in response to a rate of change of the time-averaged ratio.