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

The change of received signal strength index and packet loss rate under 2.4 GHz radio communication in a persimmon orchard in flowering phase was investigated. Texas CC2530 RF chip and the TinyOS system based WSN nodes were selected as instruments to conduct interwoven tests along a column of persimmon trees and different rows and columns of the orchard, and measure the receiving signal strength and packet loss rate which were in the three different heights from 0.80 m at the bottom of the canopy to 2.80 m at the top. In the tests, distance of each three trees was set as a tested distance, and there were eight tested distances in each row or column totally. Afterwards, all the obtained data underwent regression analysis. The results showed that when the transmitter and receiver were maintained at a fixed height, the received signal strength decreased, while the packet loss rate increased with the augment of tested distance. Furthermore, under the two situations where receiver was at the fringe of persimmon orchard and both transmitter and receiver were in the orchard, the models of signal strength attenuation affected by different factors along a row of persimmon tree were established and evaluated. Additionally, the curved surface graphs of different transceiver heights and different ranks of trees which were drawn by MATLAB software was able to reflect wireless signal transmission characteristics in persimmon orchard straightly.