Systems for delay-matched analog self-interference cancellation

• US 9,520,983 B2
• Filed: 09/11/2014
• Issued: 12/13/2016
• Est. Priority Date: 09/11/2013
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Kumu Networks, Inc.
• Inventors: Choi, Jung-Il, Jain, Mayank
• Primary Examiner(s): Shah, Chirag
• Assistant Examiner(s): Kang, Suk Jin
• Application Number:
  US14/484,094
• Publication Number:
  US 20150078217A1
• Time in Patent Office: 824 Days
• Field of Search: None
• 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 5/14 Two-way operation using the same type of signal, i.e. duplex

Abstract

A system for delay-matched analog self-interference cancellation including a transmit coupler, that samples the analog transmit signal to create a sampled analog transmit signal; a delay matcher that imposes a variable delay on the sampled analog transmit signal to create a delayed analog transmit signal; an analog self-interference canceller that transforms the delayed analog transmit signal to an analog self-interference cancellation signal; and a receive coupler, that combines the analog self-interference cancellation signal with the analog receive signal.

Claims

1. A system for delay-matched analog self-interference cancellation comprising:

a transmit coupler, communicatively coupled to an RF transmit signal of a full-duplex wireless communication system, that samples the RF transmit signal to create a sampled RF transmit signal;

a delay matcher, comprising concentric metal delay lines coupled by switches, that imposes a variable delay on the sampled RF transmit signal to create a delayed RF transmit signal;

wherein the variable delay is a function of delay line lengths and switch positions;

an analog self-interference canceller, comprising a signal divider, first and second delayers, first and second scalers, and a signal combiner, wherein the signal divider splits the delayed RF transmit signal into first and second transmit signal components, the first scaler and first delayer scale and delay the first transmit signal component to create a first self-interference cancellation signal component, the second scaler and second delayer scale and delay the second transmit signal component to create a second self-interference cancellation signal component, and the signal combiner combines the first and second self-interference cancellation signal components to form an RF self-interference cancellation signal;

an amplifier, that amplifies the RF self-interference cancellation signal; and

a receive coupler, communicatively coupled to an RF receive signal of the full-duplex wireless communication system, that combines the RF self-interference cancellation signal with the RF receive signal.

2. The system of claim 1, further comprising an analog self-interference canceller control circuit that adapts configuration parameters of the analog self-interference canceller based on at least one of transmit signal data, receive signal data, and environmental data.

3. The system of claim 2, wherein configuration parameters comprise scaler scale factors.

4. A system for delay-matched analog self-interference cancellation comprising:

a transmit coupler, communicatively coupled to an analog transmit signal of a communication system, that samples the analog transmit signal to create a sampled analog transmit signal;

a delay matcher, comprising a set of conductive delay lines and a set of switches, wherein the delay matcher imposes a variable delay on the sampled analog transmit signal to create a coarsely delayed analog transmit signal;

wherein the set of switches controls signal routing between a delay matcher input and a delay matcher output, and thus sets the variable delay; and

an analog self-interference canceller, comprising a signal divider, a set of scalers and delayers, and a signal combiner;

wherein the analog self-interference canceller passes the coarsely delayed analog transmit signal through the signal divider to produce a set of transmit signal components;

wherein the analog self-interference canceller passes the set of transmit signal components through at least a subset of the set of scalers and delayers to create a set of self-interference cancellation signal components;

wherein the analog self-interference canceller passes the self-interference cancellation signal components through the signal combiner to produce an analog self-interference cancellation signal; and

a receive coupler, communicatively coupled to an analog receive signal of the communication system, that combines the analog self-interference cancellation signal with the analog receive signal.

5. The system of claim 4, further comprising a control circuit that sets a configuration state of the analog self-interference canceller in response to at least one of sampled signal data, communication system settings, communication system characteristics, and environmental data.

6. The system of claim 5, wherein the control circuit adapts the configuration state based on at least one of historical received data, RF transmit signal content, and a test signal.

7. The system of claim 4, wherein each scaler of the set of scalers and delayers comprises an attenuator.

8. The system of claim 4, wherein the set of conductive delay lines comprises a set of concentric metal delay lines.

9. The system of claim 8, wherein the delay matcher is fabricated on a printed circuit board.

10. The system of claim 9, wherein the delay matcher further comprises ground vias positioned between metal delay lines of the set of concentric metal delay lines.

11. The system of claim 9, wherein the delay matcher is fabricated in a stripline structure.

12. The system of claim 8, further comprising a control circuit that sets a configuration state of the analog self-interference canceller in response to at least one of sampled signal data, communication system settings, communication system characteristics, and environmental data.

13. The system of claim 12, wherein the control circuit also sets the variable delay by controlling switch positions of the set of switches.

14. The system of claim 13, wherein the control circuit sets the variable delay in response to at least one of sampled signal data, communication system settings, communication system characteristics, and environmental data.