The study of human movement effect on signal strength for indoor WSN deployment

This paper proposes the use of a wireless sensor network (WSN) as a passive human behavior monitoring system for enabling intelligent green building. The proposed application required further investigation and study of the effect of human movement on wireless signals at 2.4GHz. It is important to understand the significant effect caused by human movement on the Received Signal Strength Indicator (RSSI). Several experiments are conducted using WSN mote from MEMSIC to obtain wireless attenuation models based on the number of people and movement speed. Prior to the experiments, the coexistence of different systems in the 2.4GHz frequency band is measured to select unoccupied IEEE802.15.4 channel to prevent co-channel interferences. Results show that the presence of people moving in indoor significantly affects the RSSI and the attenuation varies with the number of people and their movement speed. The attenuation model of human movement in indoor environment has enabled the use of existing WSN in the building to detect the presence of people and act as a passive sensor for human movement to enable effective lighting and air-conditioning control system.