Abstract: For monitoring an area, signal strength samples are obtained (S1) by sampling a data signal transmitted from at least one first device and received by at least one second device, and measuring a signal strength of the sampled data signal. The signal strength samples are processed (S2) by forming consecutive first groups of N consecutive signal strength samples, calculating first standard deviations for each of the consecutive first groups, forming consecutive second groups of N consecutive first standard deviations, and calculating second standard deviations for each of the consecutive second groups. Based on the second standard deviations, it is detected (S3) if a fluctuation in the data signal received by the second device has occurred that represents an intrusion in the area.

Abstract: For monitoring an area, signal strength samples are obtained (S1) by sampling a data signal transmitted from at least one first device and received by at least one second device through at least one wireless link within the area between the at least one first device and the at least one second device, and measuring a signal strength of the sampled data signal. The signal strength samples are processed (S2) by forming consecutive first groups of N consecutive signal strength samples such that two directly consecutive first groups are different by one signal strength sample, calculating first standard deviations for each of the consecutive first groups, forming consecutive second groups of N consecutive first standard deviations such that two directly consecutive second groups are different by one first standard deviation, and calculating second standard deviations for each of the consecutive second groups.