Full-Duplex Self-Interference Cancellation Systems

• US 20150318976A1
• Filed: 12/19/2014
• Published: 11/05/2015
• 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.
• Granted Patent: US 9,602,157 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• 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:

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 the first digital baseband signal 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 to a second digital baseband signal, the second RF signal including self-interference;

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; and

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.

2. The full-duplex transceiver of claim 1, wherein the digital signal processor is configured to determine the channel transfer function based upon an estimate of a wireless channel between the first antenna and the second antenna and 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 upon 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 transceiver further comprises an oscillator that provides a common reference carrier frequency to the transmit chain, the receive chain, and the auxiliary 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 self-interference canceller applies a second channel transfer function to the first digital baseband signal to generate a second cancellation signal and subtracts 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:

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 the first digital baseband signal to a first RF signal for wireless transmission;

a receive chain that receives a second RF signal and converts the second RF signal to a second digital baseband signal, the second RF signal including self-interference;

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; and

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.

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 upon a ratio of an estimate of a 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 transceiver further comprises an oscillator that provides a common reference carrier frequency to the transmit chain, the receive chain, and the auxiliary receive chain.

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 applies the second channel transfer function to the first digital baseband signal to generate a second cancellation signal and subtracts 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 over a first antenna;

receiving a second RF signal over a second antenna and converting, with a receive chain, the second RF signal to a second digital baseband signal, the second RF signal including self-interference;

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

generating a cancellation signal by applying a 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 upon an estimate of a wireless channel between the first antenna and the second antenna and an estimate of a wired channel associated with the auxiliary receive chain.

19. The method of claim 18, 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;

applying a second channel transfer function to the first digital baseband signal to generate a second cancellation signal; and

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