A method, comprising: at a receiver , receiving wireless signals from a communication channel, each wireless signal being based on a respective transmission of a reference signal by a transmitter at a distinct time; by operation of one or more processors , determining channel responses based on each of the wireless signals and the reference signal, each channel response being determined based on a respective one of the received wireless signals; by operation of the one or more processors, determining estimated received signals based on the reference signal and the channel responses; and by operation of the one or more processors, detecting motion of an object in the communication channel based on the channel responses and the estimated received signals, wherein detecting motion of the object in the communication channel based on the channel responses and the estimated received signals comprises: for each of the wireless signals determining whether the wireless signal includes a signal indicative of interference; determining whether a quality metric exceeds a first threshold value, the quality metric being based on a comparison of the wireless signal and a respective one of the estimated received signals; and using at least a portion of the channel response for motion detection when: the wireless signal is determined to not include a signal indicative of interference; and the quality metric exceeds the first threshold value; and detecting motion of the object when a variance of the used channel responses exceeds a second threshold value. at a receiver , receiving wireless signals from a communication channel, each wireless signal being based on a respective transmission of a reference signal by a transmitter at a distinct time; by operation of one or more processors , determining channel responses based on each of the wireless signals and the reference signal, each channel response being determined based on a respective one of the received wireless signals; by operation of the one or more processors, determining estimated received signals based on the reference signal and the channel responses; and by operation of the one or more processors, detecting motion of an object in the communication channel based on the channel responses and the estimated received signals, wherein detecting motion of the object in the communication channel based on the channel responses and the estimated received signals comprises: for each of the wireless signals determining whether the wireless signal includes a signal indicative of interference; determining whether a quality metric exceeds a first threshold value, the quality metric being based on a comparison of the wireless signal and a respective one of the estimated received signals; and using at least a portion of the channel response for motion detection when: the wireless signal is determined to not include a signal indicative of interference; and the quality metric exceeds the first threshold value; and detecting motion of the object when a variance of the used channel responses exceeds a second threshold value. determining whether the wireless signal includes a signal indicative of interference; determining whether a quality metric exceeds a first threshold value, the quality metric being based on a comparison of the wireless signal and a respective one of the estimated received signals; and using at least a portion of the channel response for motion detection when: the wireless signal is determined to not include a signal indicative of interference; and the quality metric exceeds the first threshold value; and the wireless signal is determined to not include a signal indicative of interference; and the quality metric exceeds the first threshold value; and detecting motion of the object when a variance of the used channel responses exceeds a second threshold value. <EOS>