Design and Development of a Wireless Sensor Network System for Precision Agriculture

Abstract

Wireless Sensor Networks (WSNs) have attracted much attention in recent years. The potential applications of WSNs are immense. They are used for collecting, storing and sharing sensed data. WSNs have been used for various applications including habitat monitoring, agriculture, nuclear reactor control, security and tactical surveillance. The WSN system developed in this project is for use in precision agriculture applications, where real time data of climatological and other environmental properties are sensed and control decisions are taken based on it to modify them. The architecture of a WSN system comprises of a set of sensor nodes and a base station that communicate with each other and gather local information to make global decisions about the physical environment. The sensor network is based on the IEEE 802.15.4 standard and a new multi-hop routing protocol was designed suited for monitoring and control applications. The aim of this research is to adapt the flat and hierarchical architectures to create a new hybrid that draws on current protocol theories. The protocol uses a hybrid network structure to achieve scalability and is source initiated along with event driven reporting to reduce the number of packet transmissions. The protocol incorporates a link quality estimation algorithm, which enables only the nodes with high quality symmetric links to be chosen for routing. Route selection is calculated using both hop count and link quality as routing metrics. The protocol is also designed such that it is computational simple, reliable, energy aware, does not impose any special hardware prerequisites and most importantly credible. Its credibility was verified by performing a series of field tests in a real world operating environment. Another aspect of the work was to make the necessary changes on the existing CMU SensorWeb platform to make it compatible with the EM50 data loggers of Decagon Devices, Inc. The base station responds to the confirmed delivery requests made by the EM50 and forwards the parsed packets to the control computer. The SensorWeb base station can receive packets from the EM50 in both Confirmed Delivery mode and Transmit Only mode. This system is currently being used to monitor water status and control irrigation for ornamental crops.