Interference cancellation methods and apparatus
Methods and apparatus for reducing and/or canceling signal interference between receiver and transmitter components of a wireless communications device are described. The methods and apparatus are well-suited for use in a wide range of devices including user equipment devices such as cell phones as well as in network equipment such as base stations. Opto-mechanical devices are used in some embodiments as part of an apparatus which performs interference cancelation on RF (Radio Frequency) signals.
1. A method of operating a wireless communications device, the method comprising:
receiving a baseband signal;
converting the baseband signal to a first radio frequency (RF) signal;
generating an optical signal based on the RF signal and a control signal;
converting the optical signal to a second RF signal; and
combining the second RF signal with a received RF signal to cancel interference between the first RF signal and the received RF signal.
2. The method of claim 1 , further comprising:
generating an acoustic signal based on the RF signal; and
generating the optical signal based on the acoustic signal.
3. The method of claim 2 , wherein the optical signal is generated by phonon-photon transduction.
4. The method of claim 3 , wherein the photon-photon transduction is based, at least in part, on the control signal.
5. The method of claim 1 , wherein the control signal comprises a delay.
6. The method of claim 5 , wherein the control signal is based at least in part on one or more of: a property of an optical waveguide of the wireless communications device through which the optical signal propagates;
or a gain of the photon-phonon transduction.
7. The method of claim 1 , wherein the baseband signal comprises a digital signal to transmit by the wireless communications device.
8. The method of claim 1 , wherein combining the second RF signal with the received RF signal comprises inverting the second RF signal.
9. The method of claim 1 , wherein the control signal is provide as input to a heating element.
10. The method of claim 9 , wherein the heating element is positioned adjacent to an optical waveguide carrying the optical signal.
11. A wireless communications device comprising:
a transmitter side defining a transmit signal path, the transmitter side comprising:
an input to receive a baseband signal;
a baseband to RF converter to convert the baseband signal to a first RF signal; and
an optical filter comprising:
a first tap to receive the first RF signal;
an RF to optical converter configured to receive the first RF signal and to output an optical signal based at least in part on a control signal;
an optical to RF converter configured to receive the optical signal and to output a second RF signal; and
a signal combiner configured to combine the second RF signal with a received RF signal in the RF domain.
12. The wireless communications device of claim 11 , wherein the optical filter comprises a heater element.
13. The wireless communications device of claim 12 , wherein the heater element is positioned adjacent to an optical waveguide through with the optical signal passes.
14. The wireless communications device of claim 12 , wherein an operation of the heater element is controlled based at least in part on the control signal.
15. The wireless communication device of claim 11 , wherein the second RF signal cancels interference with the received signal by the first RF signal.
16. The wireless communications device of claim 11 , wherein the RF to optical converter comprises an acoustic to optical transducer.
17. A transceiver comprising:
a transmit signal path comprising:
a digital input to receive a digital baseband signal;
a first baseband converter to convert the digital baseband signal into an analog baseband signal; and
an up-converter to modulate the analog baseband signal into RF domain;
a receive signal path comprising:
an analog input to receive an RF receive signal;
a down-converter to modulate the RF receive signal into analog baseband domain; and
a second baseband converter to convert the analog baseband signal into a digital output signal;
a self-interference filter comprising:
an RF to acoustic filter configured to receive an output of the up-converter of the transmit signal path;
an acoustic to optical converter configured to receive an output of the RF to acoustic filter, the acoustic to optical converter operating at least in part based on a control signal; and
an optical to RF converter configured to receive an output of the acoustic to optical converter; and
a signal combiner configured to receive an output of the optical to RF converter to generate a second RF signal to combine with the RF receive signal to cancel interference with the RF receive signal from an output of the up-converter.
18. The transceiver of claim 17 , wherein the control signal is based at least in part on an output of a channel estimator.
19. The transceiver of claim 17 , wherein the control signal defines a delay.
20. The transceiver of claim 17 , wherein the output of the up-converter and the RF receive signal are in-band.