Loss research on wireless sensor network signal transmission in persimmon orchard

Abstract: To explore a wireless sensor network (WSN) system and node deployment in persimmon orchards, this paper focused on the wireless network signal transmission under the 2.4 GHz radio channel in the persimmon orchard when it was in the germination stage, young leaves stage, and flowering stage, three growth periods. A row of persimmon tress in the growth period was selected. By adjusting the height and distance of the node and father node, the distance from three different heights from 0.80 meters at the bottom of the tree and 1.80m at the most luxuriant foliage location to 2.80 meters at the top of the canopy wee measured. Persimmon trees were measured for each growth period resulting in 72 groups of data. Results showed the LQI value with the change of the distance, the sine curve type attenuation trend, and the difference was obvious in the three growth periods. The radio signal attenuation data measured the worst minimal in the flowering stage, because the branches and leaves of signal reflection, refraction, and absorption was the most serious in this period. It is showed that the best effective transmission distance of each column of trees was 38m when child nodes and father nodes are on the top of the canopy (2.80 m) in germination, while in the young leaves stage, the height of the child nodes and father nodes are located in the top of the canopy, when the node is the best place to pitch 32m. In the flowering stage, child nodes and father nodes are on the top of the canopy, and the best distance is 26m. In the case when plant height is not very high, when the device is placed on top of the node, the wireless sensor networks optimal signal transmission distance changes as the degree of lush foliage plants is smaller and smaller. During the experiment, because the orchard in the wild environment was susceptible to the wind, the corresponding external factors, such as the difference of the instantaneous value, sometimes the LQI was big. Based on two data sets, curve fittings were established in the 2.4GHz channel signal attenuation model, which cubic polynomial model maximum correlation was coefficient R squared for an optimal model. A model of R value was the biggest of all. In the germination stage, R squared was 0.754-0.958; in the young leaves stage it was 0.805-0.979; and in the flowering stage it was 0.758-0.991. Wireless sensor network research on orchard signal transmission loss provided the technical basis for the deployment of wireless sensor network nodes in orchards.