Wireless full-duplex system and method with self-interference sampling

• US 9,413,516 B2
• Filed: 06/10/2014
• Issued: 08/09/2016
• Est. Priority Date: 11/30/2013
• Status: Active Grant

• Current Assignee: Amir Keyvan Khandani
• Original Assignee: Amir Keyvan Khandani
• Inventors: Khandani, Amir Keyvan
• Primary Examiner(s): Chan, Sai-Ming
• Application Number:
  US14/301,076
• Publication Number:
  US 20150156003A1
• Time in Patent Office: 791 Days
• Field of Search: 370/278
• US Class Current: 1/1
• CPC Class Codes: H04B 1/525 with means for reducing leakage of transmitter signal into the receiver
• CPC Class Codes: H04L 5/143 for modulated signals H04L5/1469 takes precedence

Abstract

A full-duplex transceiver is provided with componentry and methods for cancellation of nonlinear self-interference signals. The transceiver is capable of receiving an incoming radio-frequency signal that includes both a desired radio-frequency signal component and a self-interference component caused by the transceiver'"'"'s own radio-frequency transmission. The transceiver demodulates the incoming radio-frequency signal to generate a first demodulated signal. The transceiver combines an analog corrective signal with the first demodulated signal to generate a second demodulated signal with reduced self-interference. The transceiver processes the first and second demodulated signals to determine a desired incoming baseband signal and to determine nonlinear components of the self-interference signal, such as nonlinearities introduced by the transceiver'"'"'s power amplifier.

Claims

1. A method performed in a full-duplex transceiver, comprising:

generating a first analog corrective signal;

receiving an incoming radio-frequency signal, wherein the incoming radio-frequency signal includes a self-interference component and a desired radio-frequency signal component;

demodulating the incoming radio-frequency signal to generate a first demodulated signal;

combining the first analog corrective signal with the first demodulated signal to generate a second demodulated signal with reduced self-interference;

sampling the first demodulated signal to obtain a sampled self-interference component; and

processing at least the second demodulated signal and the sampled self-interference component to determine a desired incoming baseband signal.

2. The method of claim 1, wherein the processing to determine the desired incoming baseband signal includes maximal-ratio combining of at least the second demodulated signal and the sampled self-interference component.

3. The method of claim 1, wherein the processing to determine the desired incoming baseband signal includes minimum mean square error processing of at least the second demodulated signal and the sampled self-interference component.

4. The method of claim 1, wherein the first demodulated signal includes a demodulated in-phase component and a demodulated quadrature component, and wherein the sampling of the first demodulated signal includes alternately sampling the in-phase component and the quadrature component.

5. The method of claim 1, wherein the first demodulated signal includes an in-phase component and a quadrature component, and wherein the sampling of the first demodulated signal includes sampling the in-phase component and the quadrature component with a single analog-to-digital converter.

6. The method of claim 1, further comprising:

generating a second analog corrective signal at a radio frequency; and

combining the second analog corrective signal with the incoming radio-frequency signal to cancel at least a portion of the self-interference component.

7. The method of claim 6, wherein the generation of the first and second corrective signals is performed by:

generating a combined corrective signal at a digital-to-analog converter;

modulating the combined corrective signal to generate the second analog corrective signal at the radio frequency; and

filtering the combined corrective signal to generate the first analog corrective signal.

8. The method of claim 7, wherein the filtering is low-pass filtering, and the first analog corrective signal is a baseband signal.

9. The method of claim 7, wherein the filtering is bandpass filtering, and the first analog corrective signal is an intermediate-frequency signal.

10. The method of claim 1, wherein the combining of the first analog corrective signal with the first demodulated signal is performed by an operational amplifier circuit.

11. The method of claim 1, wherein the combining of the first analog corrective signal with the first demodulated signal is performed by a passive transformer circuit.

12. The method of claim 1, further comprising:

modulating an outgoing baseband signal to generate an outgoing radio-frequency communication signal;

amplifying the outgoing radio-frequency communication signal using a power amplifier; and

transmitting the outgoing radio-frequency communication signal from a transmit antenna of the full-duplex transceiver, wherein the self-interference component is caused by the transmission of the outgoing radio-frequency communication signal.

13. The method of claim 12, wherein the generating of the first analog corrective signal includes applying a first predetermined transformation to the outgoing baseband signal.

14. The method of claim 12, further comprising:

generating a second analog corrective signal at a radio frequency; and

combining the second analog corrective signal with the incoming radio-frequency signal to cancel at least a portion of the self-interference component.

15. The method of claim 12, wherein the outgoing radio-frequency communication signal is an orthogonal frequency-division multiplexing signal.

16. The method of claim 1, further comprising processing at least the sampled self-interference component to determine nonlinear distortion introduced by the power amplifier.

17. The method of claim 13, further comprising using the determined nonlinear distortion to determine the first analog corrective signal.

18. The method of claim 1, wherein the first analog corrective signal and the first demodulated signal are intermediate-frequency signals.

19. The method of claim 1, wherein the first analog corrective signal and the first demodulated signal are intermediate-frequency signals, and wherein the demodulation of the incoming radio-frequency signal to generate the first demodulated signal is performed without the use of image-rejection circuitry.

20. The method of claim 12, further comprising:

sampling the outgoing radio-frequency communication signal;

adjusting the phase and magnitude of the sampled radio-frequency communication signal to generate a radio-frequency corrective signal; and

combining the radio-frequency corrective signal with the incoming radio-frequency signal to reduce the self-interference component.

21. The method of claim 20, wherein the sampling of the outgoing radio-frequency communication signal is performed at the output of a power amplifier.

22. The method of claim 12, further comprising:

obtaining a plurality of samples of the outgoing radio-frequency communication signal;

successively adjusting the phase and magnitude of each of the sampled radio-frequency communication signals to generate a plurality of radio-frequency corrective signals; and

combining the plurality of radio-frequency corrective signals with the incoming radio-frequency signal to reduce the self-interference component.

23. The method of claim 22, wherein the plurality of samples are obtained at different frequencies.

24. The method of claim 22, wherein the adjustment of the phase and magnitude of each of the sampled radio-frequency communication signals includes adjustment of the phase and amplitude to compensate for a respective leakage path.

25. The method of claim 22, wherein adjusting the phase and magnitude of each of the sampled radio-frequency communication signals includes adjustment of a respective tunable delay circuit.

26. A full-duplex transceiver comprising:

a radio-frequency modulator configured to modulate an outgoing baseband signal into an outgoing radio-frequency communication signal;

a transmit antenna configured to transmit the outgoing radio-frequency communication signal;

a receive antenna configured to receive an incoming radio-frequency signal;

a radio-frequency demodulator configured to demodulate the incoming radio-frequency signal to generate a first demodulated signal;

a baseband correction module configured to generate a baseband analog corrective signal based on the outgoing baseband signal;

baseband signal addition circuitry configured to add the baseband analog corrective signal to the first demodulated signal to generate a second demodulated signal;

a first analog-to-digital converter configured to sample the first demodulated signal;

a second analog-to-digital converter configured to sample the second demodulated signal; and

a digital decoding module configured to determine a desired incoming baseband signal based at least on the sampled first and second demodulated signals.

27. The transceiver of claim 26, wherein the baseband signal addition circuitry includes an operational amplifier.

28. The transceiver of claim 26, wherein the signal addition circuitry includes passive transformer circuitry.

29. The transceiver of claim 26, further comprising:

a radio-frequency correction module configured to generate a radio-frequency analog corrective signal; and

radio-frequency signal addition circuitry configured to add the radio-frequency analog corrective signal to the incoming radio-frequency signal.

30. The transceiver of claim 26, wherein the digital decoding module is configured to determine the desired incoming baseband signal based on maximal-ratio combining of the sampled first and second demodulated signals.

31. The transceiver of claim 26, wherein the digital decoding module is configured to determine the desired incoming baseband signal based on minimum mean square error processing of the sampled first and second demodulated signals.