Design And Implementation Of Real-time Monitoring System Based On Offshore Wireless Sensor Network

With the advancement of information technology, modern ocean environmental monitoring technologies in today's world develop towards the direction of high level integration, high time efficiency, multi-platform, intelligence and networking, which led to the emergence of real-time monitoring system. However, even today there is no such real-time environmental data observation method except ARGO, which is of less quantity than the requirements of oceanography research because of its high price and difficulties in deployment. Wireless Sensor Network, which is the convergence of sensors, nested computation, networks and wireless communication technologies, brings opportunity to solve the problem because of its low price, easy-to-deploy and the broad application prospects in the field of real-time ocean environmental monitoring.Wireless sensor network technology has its unique advantages in ocean environmental monitoring. The nodes integrated sensors, data-processing unit and communication module can constitute a network through self-organization, used to measure the heat, infrared, optical information and other signals. This kin of network deploys convenient without the support of cables and other infrastructures. Inexpensive sensor nodes can be deployed intensively in large-scale waters. As a result, it's facile to obtain more accurate environmental information through the use of spatial correlation between nodes.The real-time monitoring system based on offshore wireless sensor network has been deployed off the seashore. It successfully applies wireless sensor network technology to the field of ocean environmental monitoring system. The system is an automatic monitoring system without manual involvement, which runs automatically by the program from data collection to the data import to the database. It is the first offshore long-term deployed test bed of wireless sensor networks in the world, which can monitor the changes of temperature, light intensity and RSSI between nodes. All the data received are transmitted to our database server by real-time and open to the researchers around the world through the web portal of our group.This system is composed of three main components including data acquisition subsystem, data transmission control subsystem and data sharing subsystem. Various subsystems are responsible for monitoring data collection, information transmission processing, data sharing and information service.This paper firstly describes the architecture of the entire system and the implementation of each module in details, especially the implementation of data acquisition subsystem including hardware packaging, software installation and environmental configuration, the design and implementation of nesC program, GPS positioning for deployment, etc. It analyzes the encountered problems during the deployment of the experiment. Through analyzing of TelosB node hardware and the energy status of routing protocols, it proposes energy-saving solutions based on energy-efficient routing and radio dormancy strategy.Our system has been running in our test bed for more than one year. Much experience during the deployment has been accumulated, such as the node packaging, energy-saving and node location. It has made an important impact on international academic circles, and provides a large amount of valuable data for Oceanography.