The Development Of Coastal Environment Monitoring System Based On Wireless Mesh Network And The Study Of Underwater Wireless Optical Communication

Oceanographic study needs data support form field observations. Therefore, state of art technology has strong impact on the progress of ocean science. It has been noted that the rapid progress of information technology has produced large amount of observation data and it is required to develop new technology for underwater data wireless transmission and multi-site observations. Because the absorbability of underwater acoustic wave is the square of frequency, acoustic link suffers the problems of narrowed bandwidth and low communication rate. Optical wireless communication has many advantages, such as wide bandwidth, high transmission rate, narrow beam, good directivity. Therefore, by integrating optical wireless communication system into underwater mobile vehicle, it provides an opportunity to gather data with high data transmission rate. The newly developed technology-Wireless Sensor Network (WSN) has characteristics of multi sensor nodes that each node has the function of information collection, data processing, performance control and data transmission. The sensor nodes can form a networked monitoring system automatically. The sensor network can cooperate with each other in the field and we will obtain complete coverage information in a large area. It has great benefit for marine environment and ecological system monitoring by deploying wireless sensor network in the area such as coast.According to the situation that our country has poor research background in underwater high speed transmission technique and wireless coastal monitoring sensor network,this paper presents the works of investigation in wireless optical communication technology with high speed transmission, and exploration of wireless Mesh sensor network in coastal monitoring application. The following is the summery of the works:(1) By make use of the advantages of Lighting Emitting Diodes (LED), such as small size, low power consumption,simple modulating circuit, high power conversion efficiency, and low cost. A wireless optical communication system has been developed for underwater data transmission at around 10 Mbit/s. It provides a new method for high speed data transmission for deep sea vehicles.(2) According to the characteristic of light-wave transmission in sea, a method for the simulation of underwater optical wireless communication system with circuit design simulator of PSpice is firstly proposed. The method for the evaluation of the performance of underwater optical communication systems during the design is presented and the results are given.(3)The method of developing a wireless Mesh sensor prototype for coastal environment monitoring based on wireless Mesh sensor network is presented. The software code based TinyOS operating system is to perform multi-hop routing for information transmission.(4)The wireless sensor network system has been constructed and the field experiments were conducted for real time application. Two sensor nodes are deployed in the College Lake at Laoshan and Qingdao No. 2 swimming beach for temperature monitoring. The experimental results are presented. It is showed that the wireless sensor network plays an important role in coastal environmental monitoring for large scale, multi site, multi sensors data gathering.