Underwater Acoustic Sensor Networks Communication And Research On Competitive MAC Protocol

In recent years,it is more important of research on acoustic sensor network with the increase of military and civilian development activities for marine resources.Since acoustic waves are used as the communication carrier in acoustic sensor network,acoustic sensor network communication would meet such problems as high delay,low bandwidth,high error rate and large signal attenuation.These problems have brought huge challenges to the research and design of acoustic sensor networks.How to build an efficient and stable acoustic sensor network communication system is quite important for the rational development of marine resources.Firstly,the research background of the acoustic sensor network and the development status of relevant technologies at home and abroad are introduced.In the current researches,sensor nodes in acoustic sensor network tend to be expensive,bulky and power-consuming.Traditional underwater MAC(media access control)protocols can not guarantee high throughput and energy performance in underwater acoustic sensor network.Aiming at this situation,this paper aims to design an acoustic sensor network based on micro-sensor nodes and competitive MAC improved protocols,which mainly include the following two parts:(1)Design of micro-acoustic sensor nodes.The research goal of this part is to design an underwater acoustic sensor device with low power consumption,small volume and transceiver function,which mainly includes hardware and embedded software design.The hardware module mainly includes power conversion circuit,micro-controller circuit based on MSP430F5335 processor,signal transmission and receiving circuits.The signal transmission circuit includes the driving amplifier circuit and the impedance matching circuit,which is designed to drive T235 hydroacoustic transducer to work normally,as a result data can be transmitted steadily through underwater channels.The signal receiving circuit includes the gain amplification circuit and the band-pass filter circuit,which can amplify and filter the weak electrical signals received by the transducer.Finally,the signal would be transmitted to the micro-controller for acquisition.Follow with the TCP/IP hierarchical model,embedded system software is divided into three parts: physical layer,application layer and data link layer.The physical layer is responsible for the initialization of hardware resources of microcontroller.The application layer takes charge of writing related applications which can realize the communication function of acoustic sensor nodes.The data link layer is responsible for designing the migration for the MAC protocol.(2)Simulation analysis and migration of competitive MAC improvement protocol.Firstly,the working principle of CW-MAC protocol based on competition window is studied in-deep.Since the protocol can't fully guarantee the fairness of channel utilization,this paper proposes two kinds of CW-MAC improved protocols named as HCW-MAC improvement protocols with differentiated competition window optimization strategy.Furthermore,CW-MAC and HCW-MAC protocols are simulated and compared by NS-3(Network Simulator V3)simulation platform.Simulation results verified that networks throughput and energy consumption performance of HCW-MAC protocols are superior to that of CW-MAC protocol,and the performance of HCW-MAC II protocol is the best.Finally,HCW-MAC II protocol migration is implemented on hardware platform,which can realize the network communication between multiple acoustic sensor nodes.In the end,the overall sensor network system is used to test the network communication.The test results show that the communication transmission success rate of the system is higher than 90%,and the communication power consumption is lower than 20 W,which meet the predetermined design requirements.