Signal transmission and node deployment of a 2.4 GHz wireless sensor network: A case study in a persimmon orchard

Abstract

<abstract> <bold>Abstract.</bold> For configuring wireless sensor network (WSN) system and node deployment in persimmon orchards, this paper focus on the change law of received signal strength index and packet loss rate under 2.4 GHz radio communication in persimmon orchard when the persimmons were flowering. The field tests were conducted along a row of persimmon tress as well as different columns of trees with the three different heights from 0.80 meters at the bottom of the canopy to 2.80 meters at the top of the canopy. Radio frequency chips were CC2530 and the WSN nodes using TinyOS operating system were selected. At each height, receiving signal strength and packet loss rate were tested based on eight different distances and the data was undergone regression analysis. Results showed that the received signal strength overall decreased while the packet loss rate increased with the rise of the communication distance when the transmitter and receiver in a certain height. The signal strength linear models in persimmon orchards along a row of persimmon tress as well as between different columns of trees were built in the circumstance of different combinations of impact factors through the received signal strength measurements for regression analysis and curve fitting. Validation results showed that the model can predict the received signal strength at different distance point at different height. Additionally, the optimum deployment location of transmitter node at each column of trees was obtained under different nodes heights and communication distance. It is showed that longest effective transmission distance of each column of trees is 49 m when transmitter and receiver are on the top of the canopy (2.80 m) while it is relative shorter with the length of 25 m when transmitter and receiver located at the most dense canopy (1.80 m).