Full-duplex self-interference cancellation systems
View Patent ↗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.
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.