Research On Underwater Acoustic Network Node System Design

In recent years,with the world to accelerate the pace of opening up the ocean,further requirements in underwater acoustic network(UAN)are put forward by civil,military and other fields.UAN is the key technology of digital intelligent Marine con-struction,which provides a convenient way in developing,recognizing and managing ocean,making the data sleeping in the sea play a great value.However,the long delay of underwater acoustic transmission,serious multipath,Doppler frequency shift and so on make the underwater acoustic channel is one of the most challenging channels.In addition,due to the complexity of the Marine environ-ment,laying a stable and reliable UAN is an urgent problem.Moreover,node's energy of UAN is limited,easily affected by the Marine environment,there will be out-of-service,large floating offset and other conditions.In order to solve the above problems,meeting the needs of UAN reliability,low power consumption and fast convergence,this paper focusing on the physical layer,data link layer and network layer protocol of UAN and successfully builds underwater communication network.The main work is summarized as follows:First,for the problem of high bit error rate in the estimation of underwater acoustic channel,using a Multi-Carrier MFSK(MC-MFSK)underwater acoustic communica-tion system program,choosing the FPGA processor implementation which is suitable for the system algorithm,reducing bit error rate in communication and obtaining relia-ble communication.Second,there is a problem that the underwater acoustic nodes are mobile and sparsely distributed,time synchronization and synchronization of cluster head and clus-ter are combined to form a fast convergence simple clustering time synchronization scheme.In addition,the efficiency of MAG A(Multiple access with collision avoidance)handshake protocol which has no response is not ideal,so the data link layer applies multi-frame confirmation and increases the node silent backoff technology to the MA-CAW protocol,improving channel utilization.Third,in order to overcome the LEACH protocol random election cluster head node and lead to its accelerated decline,making full use of the residual energy of the node,combing with time synchronization algorithm,using irregularly assigned time slot technology,an improved LEACH routing of low power consumption is proposed.And make the modified data link layer protocol and network layer routing algorithm be in integration with the physical layer,which designs and implements an efficient under-water acoustic network communication system.Fourth,the results of pool and ocean experiments show that the system achieve the MACAW handshake mechanism based on MC-MFSK communication system,which can effectively avoid single channel underwater acoustic communication conflict and establish hierarchical communication,reducing node energy consumption.The un-derwater acoustic communication system can ensure reliable communication between underwater nodes.