Research On Underwater Acoustic Sensor Networks Communication System

In recent years, there has been a tremendous amount of research on the design and implementation of Underwater Acoustic Sensor Networks (UWSNs in short) because of its broad application in fisheries, industry and national defense etc. As an important branch of wireless sensor networks, UWSNs has its own distinct characteristics, which makes the existing technologies, protocols and algorithms designed for radio networks fail to meet the special requirements of the underwater environment.In recent literature for UWSNs, protocols (especially MAC protocols) designed or improved only according to the characteristics of underwater acoustic channel (such as the limited bandwidth, long propagation delay), which rarely mentioned its practical application background clearly. There is no mature MAC protocol could be directly applied in the practical underwater project, therefore more practical MAC protocol need to be designed.hi this paper, we firstly summarizes the current research status of the UWSNs at home and abroad. And then analyzes the characteristics of underwater acoustic channel which pose challenges to the design of protocols for UWSNs.Secondly, an original transceiver circuit for acoustic Modem is designed and an acoustic frequency hopping text communication system is realized which selects low power DSP TMS320C6747 as the processor, DYW-28-GCWJ as its underwater acoustic transducer.Thirdly, the main technical challenges to the design of MAC protocols for UWSNs is introduced. And then the MAC protocols in UWSNs was classified and analyzed on the algorithm, advantages and disadvantages for each protocol.Finally, some improved mechanisms for practical MAC protocol are put forward. The topology combined master-slave topology with multi-hop topology is adopted as network configuration; The Wake-Up Mechanism, Alarm Trigger Mechanism and Relay Switch Mechanism are designed to reduce energy consumption; and AUV/UUV calibration mode is introduced to solve the clock drift problem. By simulation, we conclude the network performs more practical through adopting the above mentioned mechanisms.