Transmission Power Control based on temperature and relative humidity

In this paper we present a novel Wireless Sensor Network (WSN) Transmission Power Control (TPC) scheme based on prevailing weather conditions: temperature and relative humidity (TRH). After the analysis of several days worth of experimental data containing received signal strength indicator (RSSI) values, a strong correspondence became evident between signal loss and wireless channel weather conditions. This led us to characterize a TRH normalized gradient that describes a relative amount of power loss that is incurred when using the wireless channel. After review, we deployed this gradient with certain modifications as a gain coefficient in a novel way of compensating wireless transmission power. Meaning that a TRH TPC scheme is proposed, for more dependable wireless communications, which determines power gain using RSSI feedback. Performance metrics of a prototype TRH TPC algorithm, with differing parametric values, are presented and compared to another node with no TPC, transmitting at the same time with a fixed power level. Finally, after weighing in the full range of results, we establish a set of conditions where this TRH compensator is effective in improving the RSSI and the overall packet received rate (PRR), while operating in harsh daylight and humid conditions.