Systems and methods for frequency independent analog self-interference cancellation

• US 9,036,749 B2
• Filed: 08/11/2014
• Issued: 05/19/2015
• Est. Priority Date: 08/09/2013
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Kumu Networks, Inc.
• Inventors: Choi, Jung-Il, Jain, Mayank, Shalizi, Joseph, Mehlman, Jeff
• Primary Examiner(s): Liu, Shuwang
• Assistant Examiner(s): Bolourchi, Nader
• Application Number:
  US14/456,367
• Publication Number:
  US 20150043685A1
• Time in Patent Office: 281 Days
• Field of Search: 375/346
• US Class Current: 375/346
• CPC Class Codes: H04B 1/12 Neutralising, balancing, or compensation arrangements
• CPC Class Codes: H04B 1/525 with means for reducing leakage of transmitter signal into the receiver
• CPC Class Codes: H04L 27/2691 involving interference determination or cancellation
• CPC Class Codes: H04L 5/14 Two-way operation using the same type of signal, i.e. duplex
• CPC Class Codes: H04L 5/143 for modulated signals H04L5/1469 takes precedence
• CPC Class Codes: H04L 5/1461 Suppression of signals in the return path, i.e. bidirectional control circuits

Abstract

A system and method for analog self-interference cancellation that includes receiving an RF transmit signal of a full-duplex radio; frequency downconverting the RF transmit signal to an IF transmit signal; transforming the IF transmit signal into an IF self-interference signal using an IF analog self-interference cancelling circuit; frequency upconverting the IF self-interference signal to an RF self-interference signal; and combining the RF self-interference signal with an RF receive signal of the full-duplex radio.

Claims

1. A system for 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 having an RF carrier frequency;

a frequency downconverter, comprising a mixer, a local oscillator, and an IF filter, wherein the frequency downconverter converts, by heterodyning, the sampled RF transmit signal to an IF transmit signal having an IF carrier frequency, wherein the IF carrier frequency is less than the RF carrier frequency;

an IF analog self-interference canceller, comprising a signal divider, first and second tunable filters, first and second scalers, first and second delayers, and a signal combiner, wherein the signal divider splits the IF transmit signal into first and second signal paths, the first tunable filter filters the first signal path to form a first IF transmit signal component and the second tunable filter filters the second filter path to form a second IF transmit signal component, the first scaler and first delayer scale and delay the first IF transmit signal component to create a first IF self-interference signal component, the second scaler and second delayer scale and delay the second IF transmit signal component to create a second IF self-interference signal component, and the signal combiner combines the first and second IF self-interference signal components to form an IF self-interference signal;

a frequency upconverter comprising a mixer, a local oscillator, and an RF filter, wherein the frequency upconverter converts, by heterodyning, the IF self-interference signal to an RF self-interference signal having the RF carrier frequency; and

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

2. The system of claim 1, further comprising an IF analog self-interference canceller control circuit that adapts configuration parameters of the IF 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 tunable filter center frequencies, scaler scale factors, and delayer delays.

4. The system of claim 1, further comprising a digital self interference canceller that transforms a digital transmit signal of the full-duplex wireless communication system to a digital self-interference signal;

a digital self-interference signal converter that converts the digital self-interference signal to a digitally-sourced IF self-interference signal; and

an IF self-interference signal combiner that combines the digitally-sourced IF self-interference signal with the IF self-interference signal.

5. A system for 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 having a first RF carrier frequency;

a frequency downconverter that converts the sampled RF transmit signal to an IF transmit signal having an IF carrier frequency, wherein the IF carrier frequency is less than the first RF carrier frequency;

an IF analog self-interference canceller that transforms the IF transmit signal to an IF self-interference signal;

wherein the IF analog self-interference canceller comprises a signal divider, a set of tunable filters, a set of scalers and delayers, and a signal combiner;

wherein the IF analog self-interference canceller passes the IF transmit signal through the signal divider and the set of tunable filters to produce a set of IF transmit signal components comprising a plurality of frequency sub-bands;

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

wherein the IF analog self-interference canceller passes the IF self-interference signal components through the signal combiner to produce the IF self-interference signal;

a frequency upconverter that converts the IF self-interference signal to an RF self-interference signal having a second RF carrier frequency; and

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

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

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

8. The system of claim 5, wherein each scaler of the set of scalers and delayers comprises an attenuator.

9. The system of claim 5, wherein at least two of the plurality of frequency sub-bands overlap.

10. The system of claim 5, further comprising a digital self-interference canceller that transforms a digital transmit signal of the full-duplex wireless communication system to a digital self-interference signal;

a digital self-interference signal converter that converts the digital self-interference signal to a digitally-sourced IF self-interference signal; and

an IF self-interference signal combiner that combines the digitally-sourced IF self-interference signal with the IF self-interference signal.