Full-duplex radio frequency echo cancellation

Abstract

A system comprising a transmitter element creating an interrogation signal and transmitting the interrogation signal and a receiver element receiving a reflection signal of the interrogation signal and combining the reflection signal and a feedback signal to cancel at least a portion of radio frequency echo signals in the reflection signal.

1 - 19 . (canceled) 
     
     
         20 . A receiver, comprising:
 a demodulator configured to demodulate a signal into an in-phase signal and a quadrature signal; and   a base-band digital radio configured to receive the in-phase signal and the quadrature signal and implement a feedback loop thereon, the feedback loop configured to provide adaptation to cancel a portion of radio frequency echo signals in the signal.   
     
     
         21 . The receiver of  claim 20 , wherein the adaptation comprises real-time adaptation. 
     
     
         22 . The receiver of  claim 20 , wherein the base-band digital radio comprises digital components configured to digitally implement echo cancellation, and wherein the digital components are configured to adapt to cancel the portion of radio frequency echo signals in the signal. 
     
     
         23 . The receiver of  claim 20 , wherein the digital components are configured to adapt depending on multi-path signal propagation conditions due to movement of objects and the receiver relative to one another. 
     
     
         24 . The receiver of  claim 20 , wherein the wherein the base-band digital radio is configured to continuously re-calibrate the feedback loop by monitoring the in-phase signal and the quadrature signal for imbalances. 
     
     
         25 . The receiver of  claim 24 , wherein the wherein the base-band digital radio is configured to, upon detecting the imbalances, compute gain, phase, and offset correction factors, and to apply these factors to the feedback loop. 
     
     
         26 . The receiver of  claim 22 , wherein the digital components are configured to adapt for a calibration period by receiving a reflection signal from a known signal interrogating a known tag. 
     
     
         27 . The receiver of  claim 22 , further comprising:
 filters disposed between the in-phase signal and the base-band digital radio and between the quadrature signal and the base-band digital radio.   
     
     
         28 . The receiver of  claim 22 , wherein the feedback loop outputs an in-phase cancellation signal and a quadrature cancellation signal. 
     
     
         29 . The receiver of  claim 28 , further comprising:
 a modulator receiving the in-phase cancellation signal and the quadrature cancellation signal and a combiner forming a feedback signal as a combination of the in-phase cancellation signal and the quadrature cancellation signal.   
     
     
         30 . The receiver of  claim 29 , further comprising:
 a coupler combining the signal and the feedback signal to cancel the portion of radio frequency echo signals in the signal.   
     
     
         31 . The receiver of  claim 30 , further comprising:
 an amplifier disposed between the combiner and the coupler, the amplifier configured to provide impedance matching.   
     
     
         32 . The receiver of  claim 31 , further comprising:
 a low pass filter disposed between the amplifier and the coupler, the amplifier providing impedance matching to the low pass filter.   
     
     
         33 . A base-band digital radio, comprising:
 inputs for an in-phase signal and a quadrature signal;   outputs for an in-phase cancellation signal and a quadrature cancellation signal;   digital components configured to monitor the in-phase signal and the quadrature signal in order to drive the in-phase cancellation signal and the quadrature cancellation signal;   wherein the in-phase cancellation signal and the quadrature cancellation signal are configured to combine with the in-phase signal and the quadrature signal to adaptively cancel a portion of radio frequency echo signals therein.   
     
     
         34 . The base-band digital radio of  claim 33 , wherein the digital components are configured to adapt in real-time to cancel the portion of radio frequency echo signals in a signal formed by the in-phase signal and the quadrature signal. 
     
     
         35 . The base-band digital radio of  claim 33 , wherein the digital components are configured to adapt depending on multi-path signal propagation conditions due to movement of objects and the base-band digital radio relative to one another. 
     
     
         36 . The base-band digital radio of  claim 33 , wherein the digital components are configured to continuously re-calibrate the in-phase cancellation signal and the quadrature cancellation signal by monitoring the in-phase signal and the quadrature signal for imbalances. 
     
     
         37 . The base-band digital radio of  claim 36 , wherein the wherein the digital components are configured to, upon detecting the imbalances, compute gain, phase, and offset correction factors, and to apply these factors to the in-phase cancellation signal and the quadrature cancellation signal. 
     
     
         38 . A method, comprising:
 demodulating an incoming signal into an in-phase signal and a quadrature signal, the incoming signal comprising echo signals;   digitally processing the in-phase signal and the quadrature signal to provide real-time adaptation based on the echo signals;   continuously re-calibrating an in-phase cancellation signal and a quadrature cancellation signal based on the processing; and   coupling the incoming signal with a combination of the in-phase cancellation signal and the quadrature cancellation signal.   
     
     
         39 . The method of  claim 38 , wherein the echo signals comprising an error component based on any of signal energy coupled from a transmitter, signal energy reflected from an antenna, and signal energy reflected from non-radio frequency identification (RFID) elements in an environment.