Wireless sensing system with coverage extension using one or more analog repeaters

A method performed in a wireless sensing system for detecting changes in a physical environment based on Channel State Information, CSI, the wireless sensing system comprising a number of N network nodes, a first network node being a receiving node configured to detect changes in the physical environment, an i-th network node being a relaying node, i=2, . . . N−1, and an N-th network node being a transmitting node and configured to transmit a signal, the method comprising:

• amplifying by the i-th network node, a received signal from the (i+1)-th network node;
• sending by the i-th network node, the amplified signal to the (i−1)-th network node;
• detecting by the first network node, if any signal is transmitted from the second network node;
• estimating by the first network node, CSI for a channel between the first and N-th network nodes via one or more relay nodes from the (N−1)-th network node to the second network node based on the received signal from the second network node;
• and
• determining by the first network node, whether there is a change in the physical environment based on the estimated CSI for the channel between the first and N-th network nodes.