Systems and methods for configurable hybrid self-interference cancellation

• US 10,804,943 B2
• Filed: 08/13/2019
• Issued: 10/13/2020
• Est. Priority Date: 02/27/2018
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Kumu Networks, Inc.
• Inventors: Hahn, Wilhelm Steffen, Riddle, Alfred, Landi, Ernie, Sieh, Dai, Choi, Jung-Il, Jain, Mayank
• Primary Examiner(s): Nguyen, Tuan H
• Application Number:
  US16/539,759
• Publication Number:
  US 20190372611A1
• Time in Patent Office: 427 Days
• CPC Class Codes: H04B 1/10 Means associated with receiver for limiting or suppressing noise or interference
• CPC Class Codes: H04B 1/40 Circuits
• 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 self-interference cancellation includes a frequency downconverter that decomposes a sampled RF transmit signal into an in-phase transmit signal and a quadrature transmit signal; a first analog vector modulator that scales the transmit signals to generate first scaled transmit signals; a second analog vector modulator that scales delayed transmit signals to generate second scaled transmit signals; a frequency upconverter that recomposes the scaled transmit signals into an RF self-interference cancellation signal; and a receive coupler that that combines the RF self-interference cancellation signal with a RF receive signal to reduce self-interference.

Claims

1. A system for self-interference cancellation comprising:

a transmit coupler, communicatively coupled to a radio frequency (RF) transmit signal of a communication system, that samples the RF transmit signal to create a sampled RF transmit signal having an RF carrier frequency;

a first analog-self-interference canceller comprising;

a frequency downconverter that decomposes the sampled RF transmit signal into an in-phase transmit signal component and a quadrature transmit signal component;

a first sampling coupler that splits the in-phase transmit signal component into a first-path in-phase transmit signal component and a second-path in-phase transmit signal component;

a second sampling coupler that splits the quadrature transmit signal component into a first-path quadrature transmit signal component and a second-path quadrature transmit signal component;

a first analog vector modulator that scales the first-path in-phase transmit signal component to generate a first scaled in-phase transmit signal component and scales the first-path quadrature transmit signal component to generate a first scaled quadrature transmit signal component;

a first delayer that delays the second-path in-phase transmit signal component to generate a first delayed in-phase transmit signal component;

a second delayer that delays the second-path quadrature transmit signal component to generate a first delayed quadrature transmit signal component;

a first combining coupler that generates an in-phase self-interference cancellation signal component based on the first scaled in-phase transmit signal component and the first delayed in-phase transmit signal component;

a second combining coupler that generates a quadrature self-interference cancellation signal component based on the first scaled quadrature transmit signal component and the first delayed quadrature transmit signal component; and

a frequency upconverter that generates an RF self-interference cancellation signal from the in-phase self-interference cancellation signal component and the quadrature self-interference cancellation signal component; and

a receive coupler, communicatively coupled to an RF receive signal of the communication system, that combines the RF self-interference cancellation signal with the RF receive signal, resulting in an RF composite receive signal;

wherein the RF composite receive signal contains less self-interference than the RF receive signal.

2. The system of claim 1, wherein at least one of the first and second delayers is an active delayer.

3. The system of claim 2, wherein:

the first analog-self-interference canceller further comprises a second analog vector modulator that scales the first delayed in-phase transmit signal component and scales the first delayed quadrature transmit signal component;

the first combining coupler receives the first delayed in-phase transmit signal component from the second analog vector modulator; and

the a second combining coupler receives the first delayed quadrature transmit signal component from the second analog vector modulator.

4. The system of claim 3, wherein the active delayer is configurable to alter a delay length imposed on a signal delayed by the active delayer.

5. The system of claim 4, wherein the active delayer comprises a bank of switchable capacitors.

6. The system of claim 4, wherein the delay length is configured based on a phase shift delay imposed by the second analog vector modulator.

7. The system of claim 2, wherein the active delayer comprises an impedance matching network.

8. The system of claim 1, wherein the transmit coupler is an active coupler comprising a power amplifier.

9. The system of claim 8, further comprising a transmitter amplifier communicatively coupled to a transmitter of the communication system, wherein the transmitter amplifier comprises the power amplifier.

10. The system of claim 1, further comprising:

a first amplifier that amplifies the first-path in-phase transmit signal component and provides the first-path in-phase transmit signal component to the first analog vector modulator; and

a second amplifier that amplifies the first-path quadrature transmit signal component and provides the first-path quadrature transmit signal component to the first analog vector modulator.

11. The system of claim 10, further comprising a third amplifier that amplifies the RF self-interference cancellation signal prior to combination with the RF receive signal.

12. The system of claim 1, wherein the in-phase transmit signal component and the quadrature transmit signal component both have an intermediate frequency (IF) carrier frequency;

wherein the IF carrier frequency is less than the RF carrier frequency.

13. The system of claim 12, wherein the IF carrier frequency is o Hertz.

14. The system of claim 1, wherein:

the first analog vector modulator generates the first scaled in-phase transmit signal component from a first linear combination of the first-path in-phase transmit signal component and the first-path quadrature transmit signal component; and

the first analog vector modulator generates the first scaled quadrature transmit signal component from a second linear combination of the first-path in-phase transmit signal component and the first-path quadrature transmit signal component.

15. The system of claim 14, wherein:

a complex signal represented by the first-path in-phase transmit signal component and the first-path quadrature transmit signal component contains both of an intended signal and an image signal;

the image signal is a complex conjugate of the intended signal; and

the first analog vector modulator generates the first and second linear combinations based on a signal power ratio of the image signal to the intended signal.

16. The system of claim 1, wherein:

the first analog vector modulator generates the first scaled in-phase transmit signal component and the first scaled quadrature transmit signal component using a differential attenuator circuit that scales signals by a total scale factor;

the differential attenuator circuit defines a set of scaling stages;

the set of scaling stages is connected to the differential attenuator circuit by a set of switches; and

the total scale factor is set by a state configuration of the set of switches.

17. The system of claim 16, wherein:

a first stage of the set of scaling stages is tuned periodically over a first period;

a second stage of the set of scaling stages is tuned periodically over a second period, wherein the first period is an integer multiple of the second period;

the first stage is communicatively coupled between an input and an output of the differential attenuator circuit; and

the second stage is communicatively coupled between the first stage and the output.

18. The system of claim 1, further comprising:

a second transmit coupler, communicatively coupled to a second RF transmit signal of the communication system, that samples the second RF transmit signal to create a sampled second RF transmit signal; and

a second analog-self-interference canceller that generates a second RF self-interference cancellation signal based on the sampled second RF transmit signal;

wherein the receive coupler further combines the second RF self-interference cancellation signal with the RF receive signal to generate the RF composite receive signal.

19. The system of claim 18, further comprising a second receive coupler communicatively coupled to a second RF receive signal of the communication system, wherein:

the first analog-self-interference canceller generates a third RF self-interference cancellation signal based on the sampled RF transmit signal;

the second analog-self-interference canceller generates a fourth RF self-interference cancellation signal based on the sampled second RF transmit signal; and

the second receive coupler combines the third and fourth RF self-interference cancellation signals with the second RF receive signal, resulting in a second RF composite receive signal;

wherein the second RF composite receive signal contains less self-interference than the second RF receive signal.

20. The system of claim 19, further comprising:

a first switch operable between a first mode, in which the sampled RF transmit signal is coupled to the first analog-self-interference canceller, and a second mode, in which the sampled RF transmit signal is coupled to the second analog-self-interference canceller; and

a second switch operable between a third mode, in which the sampled second RF transmit signal is coupled to the first analog-self-interference canceller, and a fourth mode, in which the sampled second RF transmit signal is coupled to the second analog-self-interference canceller.