The influence of received signal strength measurement methods on the accuracy of distance estimation in wireless sensor network

Received signal strength (RSS) has been a favourable method in distance and position estimation of sensor nodes in Wireless Sensor Networks (WSN) due to the low cost solution offered. However RSS is highly affected by a range of factors including slight changes in the environment (e.g. the presence of obstacles and multipath) and equipment used. These factors contribute to large variations in the RSS and consequently lead to inaccuracy in distance estimation. In this paper, the variations in the RSS due to the environment and equipment uncertainties and its impact on the distance estimation from the measurements point of view were investigated. Measurements using high performance equipment in a controlled environment of an anechoic chamber were conducted. More specifically, distant-independent (DI) RSS measurements where distance between the transmitter and receiver are kept constant were carried out at different locations in the chamber and the results are compared with measurements using varying distance (distant-dependent (DD)) RSS measurements. The analysis carried out show that DI method gives a more accurate RSS measurement in the environment and consequently better distance estimation than DD at 12cm error for 95% of samples as compared to 35cm error for DD measurements.