Development and Evaluation of a Wireless Sensor Network Monitoring System in Various Agricultural Environments

摘要

A wireless sensor network-based agricultural monitoring system was developed. Soil moisture and air temperature/humidity were monitored by sensor nodes of the WSN. The collected information was transmitted wirelessly to a gateway node which was connected to a computer. Considering variable conditions under different agricultural applications, a series of field experiments was conducted to evaluate the performance of the developed WSN system. The communication distance, energy consumption and data transmission performance of the system were tested under three crop environments: a greenhouse, an open farmland and an orchard. The results demonstrate that the received power attenuated sinusoidally with the increasing distance between a transmitter and a receiver. Reliable signal transmission could be achieved under different environments and at different testing distances. Because the sensor nodes in the greenhouse were closer to the gateway node and the signals in the greenhouse were more prone to be affected by phenomena such as reflection, diffraction and refraction, the RF signals attenuated more slowly and the packet loss rate was lower. In the open farmland and the orchard, as a result of the sparse winter foliage, the shielding effect of the crops was weaker. Thus, the further the transmission distance, the larger the RF signal's attenuation. Packet loss was more likely to occur if the sensor nodes were far from the gateway node. The average packet loss rate was 7.6%. The effective communication distance between nodes was more than 200 m in the open field environment.