Combined Human, Antenna Orientation in Elevation Direction and Ground Effect on RSSI in Wireless Sensor Networks

TL;DR

This study experimentally examines how human presence, antenna elevation orientation, and ground effects influence RSSI in wireless sensor networks, highlighting the need for improved human activity detection algorithms.

Contribution

It provides new insights into how antenna tilt, ground effects, and human movement impact RSSI, informing better activity detection methods in WSNs.

Findings

Antenna orientation significantly affects RSSI fluctuations.

Human presence causes notable RSSI variation even without movement.

Ground effects influence RSSI range and fluctuation patterns.

Abstract

In this paper, we experimentally investigate the combined effect of human, antenna orientation in elevation direction and the ground effect on the Received Signal Strength Indicator (RSSI) parameter in the Wireless Sensor Network (WSN). In experiment, we use MICAz motes and consider different scenarios where antenna of the transmitter node is tilted in elevation direction. The motes were placed on the ground to take into account the ground effect on the RSSI. The effect of one, two and four persons on the RSSI is recorded. For one and two persons, different walking paces e.g. slow, medium and fast pace, are analysed. However, in case of four persons, random movement is carried out between the pair of motes. The experimental results show that some antenna orientation angles have drastic effect on the RSSI, even without any human activity. The fluctuation count and range of RSSI in different scenarios with same walking pace are completely different. Therefore, an efficient human activity algorithm is need that effectively takes into count the antenna elevation and other parameters to accurately detect the human activity in the WSN deployment region.