Full-duplex self-interference cancellation systems

• US 10,256,864 B2
• Filed: 02/27/2017
• Issued: 04/09/2019
• Est. Priority Date: 05/05/2014
• Status: Active Grant

• Current Assignee: Regents of the University of California (University of California)
• Original Assignee: Regents of the University of California (University of California)
• Inventors: Eltawil, Ahmed Mohamed, Ahmed, Elsayed A.
• Primary Examiner(s): Mui, Gary
• Application Number:
  US15/443,430
• Publication Number:
  US 20170170948A1
• Time in Patent Office: 771 Days
• CPC Class Codes: H04B 1/123 using adaptive balancing or compensation means adaptive filter circuits and algorithms H03H
• CPC Class Codes: H04B 1/44 Transmit/receive switching
• CPC Class Codes: H04B 1/525 with means for reducing leakage of transmitter signal into the receiver
• CPC Class Codes: H04L 5/1461 Suppression of signals in the return path, i.e. bidirectional control circuits

Abstract

Embodiments of full-duplex self-interference cancellation systems are described. In one embodiment, a full-duplex transceiver includes a digital signal processor that processes digital signals, a transmit chain that receives a first digital baseband signal from the digital signal processor and converts it to a first RF signal, a receive chain that receives a second RF signal and converts the second RF signal to a second digital baseband signal, and an auxiliary receive chain that receives a portion of the first RF signal and converts it to an auxiliary digital baseband signal. The transceiver may further include a self-interference canceller that applies a channel transfer function to the auxiliary digital baseband signal to generate a cancellation signal and subtracts the cancellation signal from the second digital baseband signal to cancel self-interference at the transceiver. The suppression of self-interference in the transceiver assists the transceiver to achieve higher efficiency in full-duplex communications.

Claims

1. A full-duplex transceiver for radio frequency (RF) communications, comprising:

an oscillator that provides a reference carrier frequency;

a transmit chain that converts a first digital baseband signal using the reference carrier frequency to a first RF signal for wireless transmission over a first antenna;

a receive chain that receives a second RF signal over a second antenna and converts the second RF signal using the reference carrier frequency to a second digital baseband signal;

an auxiliary receive chain that receives a portion of the first RF signal from the transmit chain and converts the portion of the first RF signal to an auxiliary digital baseband signal;

a digital signal processor configured to determine a channel transfer function based on an estimate of a wireless channel between the first antenna and the second antenna; and

a self-interference canceller configured to;

generate a cancellation signal based on an application of the channel transfer function to the auxiliary digital baseband signal; and

subtract the cancellation signal from the second digital baseband signal.

2. The full-duplex transceiver of claim 1, wherein the digital signal processor is configured to determine the channel transfer function based further on an estimate of a wired channel associated with the auxiliary receive chain.

3. The full-duplex transceiver of claim 2, wherein the digital signal processor is configured to determine the channel transfer function based on a ratio of the estimate of the wireless channel and the estimate of the wired channel.

4. The full-duplex transceiver of claim 1, wherein the oscillator comprises one or more oscillators that each provides a reference carrier frequency at a same frequency for use by the transmit chain and the receive chain.

5. The full-duplex transceiver of claim 1, wherein the digital signal processor is configured to determine the channel transfer function at a predetermined tuning periodicity to reduce an estimation error in the channel transfer function.

6. The full-duplex transceiver of claim 1, wherein the digital signal processor is configured to determine estimation error in the channel transfer function using training symbols inserted in frames during a normal operating mode of the transceiver.

7. The full-duplex transceiver of claim 6, wherein:

the digital signal processor is further configured to determine a second channel transfer function based on the estimation error in the channel transfer function; and

the self-interference canceller is further configured to;

generate a second cancellation signal based on an application of the second channel transfer function to the first digital baseband signal; and

subtract the second cancellation signal from the second digital baseband signal.

8. The full-duplex transceiver of claim 7, wherein the digital signal processor is configured to determine the second channel transfer function based on the estimation error in the channel transfer function.

9. A full-duplex transceiver for radio frequency (RF) communications, comprising:

an oscillator that provides a reference carrier frequency;

a transmit chain that converts a first digital baseband signal using the reference carrier frequency to a first RF signal for wireless transmission;

a receive chain that receives a second RF signal converts the second RF signal using the reference carrier frequency to a second digital baseband signal;

an auxiliary receive chain that receives a portion of the first RF signal from the transmit chain and converts the portion of the first RF signal to an auxiliary digital baseband signal;

a digital signal processor configured to determine a channel transfer function based on an estimate of a wireless channel between the transmit chain and the receive chain; and

a self-interference canceller configured to;

generate a cancellation signal based on an application of the channel transfer function to the auxiliary digital baseband signal; and

subtract the cancellation signal from the second digital baseband signal.

10. The full-duplex transceiver of claim 9, wherein the portion of the first RF signal is provided by a power splitter.

11. The full-duplex transceiver of claim 9, wherein the portion of the first RF signal is taken from an output of a mixer in the transmit chain.

12. The transceiver of claim 9, wherein the digital signal processor is configured to determine the channel transfer function based on a ratio of the estimate of the wireless channel and an estimate of a wired channel associated with the auxiliary receive chain.

13. The full-duplex transceiver of claim 9, wherein the auxiliary receive chain converts the portion of the first RF signal to the auxiliary digital baseband signal using the reference carrier frequency.

14. The full-duplex transceiver of claim 9, wherein the digital signal processor is configured to determine the channel transfer function at a predetermined tuning periodicity to reduce an estimation error in the channel transfer function.

15. The full-duplex transceiver of claim 9, wherein the digital signal processor is configured to determine estimation error in the channel transfer function using training symbols inserted in frames during a normal operating mode of the transceiver.

16. The full-duplex transceiver of claim 15, wherein:

the digital signal processor is configured to determine a second channel transfer function based on the estimation error in the channel transfer function; and

the self-interference canceller is further configured to;

generate a second cancellation signal based on an application of the second channel transfer function to the first digital baseband signal; and

subtract the second cancellation signal from the second digital baseband signal.

17. A method of self-interference cancellation in a full-duplex transceiver, comprising:

converting, with a transmit chain, a first digital baseband signal to a first RF signal for wireless transmission using a reference carrier frequency;

receiving a second RF signal and converting, with a receive chain, the second RF signal to a second digital baseband signal using the reference carrier frequency;

converting, with an auxiliary receive chain, a portion of the first RF signal to an auxiliary digital baseband signal;

determining a channel transfer function based on an estimate of a wireless channel between the transmit chain and the receive chain;

generating a cancellation signal based on an application of the channel transfer function to the auxiliary digital baseband signal; and

subtracting the cancellation signal from the second digital baseband signal.

18. The method of claim 17, further comprising determining the channel transfer function based further on an estimate of a wired channel associated with the auxiliary receive chain.

19. The method of claim 17, further comprising determining the channel transfer function during a periodic tuning phase interval of the transceiver.

20. The method of claim 17, further comprising:

determining an estimation error in the channel transfer function using training symbols inserted in frames during a normal operating mode of the transceiver;

generating a second cancellation signal based on an application of a second channel transfer function to the first digital baseband signal; and

subtracting the second cancellation signal from the second digital baseband signal.