US Patent 10051414 Detecting motion based on decompositions of channel response variations

In a general aspect, motion is detected using vector representations of channel responses. In some aspects, a first set of channel responses are obtained based on wireless signals transmitted through a space during a first time period. From the first set of channel responses, a set of orthogonal axes in a frequency vector domain are determined. A second channel response is obtained based on a wireless signal transmitted through the space during a second time period, and a channel vector representing the second channel response in the frequency vector domain is determined. Motion of an object in the space is detected based on a projection of the channel vector onto one of the set of orthogonal axes.