US Patent 9584974 Detecting motion based on reference signal transmissions

In a general aspect, motion of an object is detected based on wireless signals. In some aspects, a receiver in a space receives wireless signals; the wireless signals are based on transmissions of a reference signal by a transmitter. Each of the received wireless signals is based on a respective transmission of the reference signal at a distinct time. Channel responses are determined based on the received wireless signals and the reference signal. Each channel response is determined based on a respective one of the received wireless signals. Motion of an object in the space is detected based on the channel responses.