Radio frequency self-interference-cancelled full-duplex relays

1. A single-input, single-output 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;

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 analog self-interference canceller that generates, in the RF domain and without performing frequency downconversion, a first self-interference cancellation signal based on the first analog transmit signal, and combines the first self-interference cancellation signal with the first analog receive signal;

a second analog self-interference canceller that generates, in the RF domain and without performing frequency downconversion, a second self-interference cancellation signal based on the second analog transmit signal, and combines the second self-interference cancellation signal with the second analog receive signal;

a third analog self-interference canceller that generates, in the RF domain and without performing frequency downconversion, a third self-interference cancellation signal based on the first analog transmit signal, and combines the third self-interference cancellation signal with the second analog receive signal; and

a fourth analog self-interference canceller that generates, in the RF domain and without performing frequency downconversion, a fourth self-interference cancellation signal based on the second analog transmit signal, and combines the fourth self-interference cancellation signal with the first analog receive signal;

wherein the first transmitter and the second transmitter may transmit simultaneously.

2. The relay of claim 1 , wherein the first digital transmit signal is substantially similar to the first digital receive signal; wherein the second digital transmit signal is substantially similar to the second digital receive signal.

3. The relay of claim 1 , wherein the first, second, third, and fourth analog self-interference cancellers generate self-interference cancellation signals by combining filtered, scaled, and delayed versions of analog transmit signals.

4. The relay of claim 1 , further comprising a digital self-interference canceller, wherein the digital self-interference canceller generates a fifth self-interference cancellation signal based on the first digital transmit signal; wherein the fifth self-interference cancellation signal is combined with the first digital receive signal.

5. The relay of claim 4 , wherein the digital self-interference canceller generates a sixth self-interference cancellation signal based on the second digital transmit signal; wherein the sixth self-interference cancellation signal is combined with the second digital receive signal.

6. The relay of claim 5 , wherein the fifth self-interference cancellation signal is generated based on both of the first and second digital transmit signals; wherein the sixth self-interference cancellation signal is generated based on both of the first and second digital transmit signals.

7. The relay of claim 5 , wherein the digital self-interference canceller generates the fifth and sixth self-interference cancellation signals according to a digital transform configuration.

8. A MIMO relay comprising:

a first transmitter, that communicates with a first wireless communication device, coupled to first and second signal paths of the relay, that converts first and second digital transmit signals received via the first and second signal paths to first and second analog transmit signals, and transmits the first and second analog transmit signals via the first and second signal paths;

a first receiver, that communicates with the first wireless communication device, coupled to the first and second signal paths of the relay, that receives first and second analog receive signals via the first and second signal paths, and converts the first and second analog receive signals to first and second digital receive signals;

a second transmitter, that communicates with a second wireless communication device independent from the first wireless communication device, coupled to third and fourth signal paths of the relay, that converts third and fourth digital transmit signals received via the third and fourth signal paths to third and fourth analog transmit signals, and transmits the third and fourth analog transmit signals via the third and fourth signal paths;

a second receiver, that communicates with the second wireless communication device, coupled to the third and fourth signal paths of the relay, that receives third and fourth analog receive signals via the third and fourth signal paths, and converts the third and fourth analog receive signals to third and fourth digital receive signals;

a first analog self-interference canceller that generates, in the RF domain and without performing frequency downconversion, a first self-interference cancellation signal based on the first analog transmit signal and combines the first self-interference signal with the first analog receive signal;

a second analog self-interference canceller that generates a second self-interference cancellation signal based on the second analog transmit signal and combines the second self-interference signal with the second analog receive signal;

a third analog self-interference canceller that generates a third self-interference cancellation signal based on the third analog transmit signal and combines the third self-interference signal with the third analog receive signal;

a fourth analog self-interference canceller that generates a fourth self-interference cancellation signal based on the fourth analog transmit signal and combines the fourth self-interference signal with the fourth analog receive signal;

a fifth analog self-interference canceller that generates a fifth self-interference cancellation signal from the first analog transmit signal and combines the fifth self-interference cancellation signal with the second analog receive signal;

a sixth analog self-interference canceller that generates a sixth self-interference cancellation signal from the second analog transmit signal and combines the sixth self-interference cancellation signal with the first analog receive signal;

a seventh analog self-interference canceller that generates a seventh self-interference cancellation signal from the first analog transmit signal and combines the seventh self-interference cancellation signal with the fourth analog receive signal; and

an eighth analog self-interference canceller that generates an eighth self-interference cancellation signal from the second analog transmit signal and combines the eighth self-interference cancellation signal with the third analog receive signal;

wherein the first transmitter and the second transmitter may transmit simultaneously.