Device-free indoor human presence detection method based on the information entropy of RSSI variations

At microwave frequencies, absorption by molecular resonance is a major factor affecting radio propagation. Irregularities in the radio propagation pattern, expressed in a form of the received signal strength indicator´s (RSSI) variations, can indicate the possible presence of a human within the radio network. The proposed human presence detection method is based on the information entropy calculated over a set of principal components extracted from a sequence of RSSI samples incrementally, without estimating the covariance matrix. By applying the entropy algorithm, the information on human presence is quantified from the sequence of principal components. It is shown that throughthe- wall human activities, which introduce disturbances in the RSSI footprint of the monitoring room, do not affect the detection accuracy of the method. Experimental results obtained for the 2.4 GHz indoor radio network assess the feasibility of the proposed approach.