Methods and apparatus for canceling distortion in full-duplex transceivers

A method to reduce distortion in a full-duplex transceiver, comprising:

• generating a first digital signal;
• generating a first analog signal based on the first digital signal for transmission over a full-duplex channel;
• receiving a second analog signal via the full-duplex channel;
• generating a second digital signal based on the second analog signal, wherein the second digital signal includes coupling distortion based on the first analog signal;
• generating an adaptive filter signal based on the first digital signal;
• and
• reducing the coupling distortion from the second digital signal by subtracting the adaptive filter signal from the second digital signal;
• wherein reducing the coupling distortion comprises generating a third digital signal by subtracting the adaptive filter signal from the second digital signal.

An adaptive filter to reduce distortion in a full-duplex transceiver, comprising:

• a full-duplex transceiver, configured to:
• receive a first digital baseband signal and generate a first analog signal based on the first digital baseband signal;
• transmit the first analog signal over a full-duplex channel via a duplexer and an antenna;
• receive a second analog signal on the antenna via the duplexer, wherein the second analog signal includes coupling distortion based on the first analog signal;
• output a second digital baseband signal based on the second analog signal, wherein the second digital baseband signal includes a digital representation of the coupling distortion;
• and
• an adaptive filter, configured to:
• generate a first-order intermodulation distortion product or a second-order intermodulation distortion product based on the first digital baseband signal;
• update a least-means-squared filter based on a third digital baseband signal and one of the first-order intermodulation product or the second-order intermodulation product, wherein the third digital baseband signal is received before the second digital baseband signal;
• generating an adaptive filter product based on the first digital baseband signal and the least-means-squared filter;
• and
• reducing the coupling distortion in the second digital baseband signal by subtracting the adaptive filter product from the second digital baseband signal.