Optically enhanced self-interference cancellation

An optically-enhanced relay comprising:

• a first transmitter, coupled to a first signal path of the relay, that converts a first digital transmit signal received via the first signal path to a first analog transmit signal, and transmits the first analog transmit signal via the first signal path;
• a first receiver, coupled to the first signal path of the relay, that receives a first analog receive signal via the first signal path, and converts the first analog receive signal to a first digital receive signal;
• a second transmitter, coupled to a second signal path of the relay, that converts a second digital transmit signal received via the second signal path to a second analog transmit signal, and transmits the second analog transmit signal via the second signal path, wherein the relay is a single-input single-output relay, wherein the first and second transmitter are operable to transmit concurrently;
• a second receiver, coupled to the second signal path of the relay, that receives a second analog receive signal via the second signal path, and converts the second analog receive signal to a second digital receive signal;
• a first optically-enhanced analog self-interference canceller that generates a first self-interference cancellation signal based on at least one of the first digital transmit signal and the first analog transmit signal, and combines the first self-interference cancellation signal with at least one of the first digital receive signal and the first analog receive signal, wherein the optically-enhanced analog self-interference canceller comprises an optical upconverter, wherein generating the first self-interference cancellation signal comprises converting a signal to optical frequency at the optical upconverter;
• a second optically-enhanced analog self-interference canceller that generates a second self-interference cancellation signal based on at least one of the second digital transmit signal and the second analog transmit signal, and combines the second self-interference cancellation signal with at least one of the second digital receive signal and the second analog receive signal;
• a third optically-enhanced analog self-interference canceller that generates a third self-interference cancellation signal based on at least one of the first digital transmit signal and the first analog transmit signal, and combines the third self-interference cancellation signal with at least one of the second digital receive signal and the second analog receive signal;
• and
• a fourth optically-enhanced analog self-interference canceller that generates a fourth self-interference cancellation signal based on at least one of the second digital transmit signal and the second analog transmit signal, and combines the fourth self-interference cancellation signal with at least one of the first digital receive signal and the first analog receive signal.