A computer-implemented motion detection method comprising: receiving first received signals indicative of wireless signals transmitted through a space over one or more paths by one or more wireless communication devices; determining, from the first received signals, channel responses associated with motion of an object in a distinct region within the space; by operation of one or more processors, identifying a characteristic shared by each of the channel responses, wherein the characteristic corresponds to a channel frequency profile of the respective channel response, the channel frequency profile comprising magnitudes of channel frequency components of the respective channel response; associating, in a motion detection database, the characteristic with the distinct region within the space; and after associating the characteristic with the distinct region within the space: receiving second received signals indicative of wireless signals transmitted through space over the one or more paths by one or more communication devices; determining, from the second received signals, additional channel responses based on wireless signals transmitted through the space over the one or more paths between the wireless communication devices; and using the motion detection database to identify motion in the distinct region; wherein each channel response, and each additional channel response is represented as: where Σ k represents a sum over all paths k, Σ n = − ∞ ∞ represents a sum over all frequency components and α n,k represents an attenuation factor for the n th frequency component along path k of respective wireless signals transmitted through the space over the one or more paths by one or more wireless communication devices. receiving first received signals indicative of wireless signals transmitted through a space over one or more paths by one or more wireless communication devices; determining, from the first received signals, channel responses associated with motion of an object in a distinct region within the space; by operation of one or more processors, identifying a characteristic shared by each of the channel responses, wherein the characteristic corresponds to a channel frequency profile of the respective channel response, the channel frequency profile comprising magnitudes of channel frequency components of the respective channel response; associating, in a motion detection database, the characteristic with the distinct region within the space; and after associating the characteristic with the distinct region within the space: receiving second received signals indicative of wireless signals transmitted through space over the one or more paths by one or more communication devices; determining, from the second received signals, additional channel responses based on wireless signals transmitted through the space over the one or more paths between the wireless communication devices; and using the motion detection database to identify motion in the distinct region; wherein each channel response, and each additional channel response is represented as: where Σ k represents a sum over all paths k, Σ n = − ∞ ∞ represents a sum over all frequency components and α n,k represents an attenuation factor for the n th frequency component along path k of respective wireless signals transmitted through the space over the one or more paths by one or more wireless communication devices. receiving second received signals indicative of wireless signals transmitted through space over the one or more paths by one or more communication devices; determining, from the second received signals, additional channel responses based on wireless signals transmitted through the space over the one or more paths between the wireless communication devices; and using the motion detection database to identify motion in the distinct region; wherein each channel response, and each additional channel response is represented as: where Σ k represents a sum over all paths k, Σ n = − ∞ ∞ represents a sum over all frequency components and α n,k represents an attenuation factor for the n th frequency component along path k of respective wireless signals transmitted through the space over the one or more paths by one or more wireless communication devices.