Underwater Acoustic Communication Hybrid Network Protocol Design And Low-Power Platform Implementation

With the improvement of comprehensive national power and the deepening development of ocean power strategy,the demand for marine equipment becomes more and more urgent,and the Underwater Acoustic Communication network is a basic facility for the development of marine exploration,so the research on Underwater Acoustic Communication network is of great significance.Most of the current research on Underwater Acoustic Communication networks focuses on improving the network concurrency and transmission rate of MAC layer communication protocols.In this paper,from the actual needs of the network,the physical layer uses Underwater Acoustic Communication spread spectrum communication,and the network reliability is the main reason to design the network protocol.First,through the theoretical study of the MAC layer protocols of classical Underwater Acoustic Communication networks,the simulation implementation process of each classical protocol is given.The NS3(Network Simulator 3)simulation software is used to simulate the Pure-ALOHA protocol,ALOHA-CS(ALOHA-Carrier Sense)protocol,TDMA(Time Division Multiple Address)protocol and MACAW(Multiple Access with Collision Avoidance for Wireless)protocol,and the end-to-end delay,throughput and packet loss rate comparison data of each protocol are obtained through simulation.Then,the experimental data are used to analyze the advantages and disadvantages of each classical protocol and the applicable network application environment,so as to design a suitable MAC layer protocol for the network with specific network requirements.Secondly,the application background of three-dimensional communication by sea,land and air is combined with the convergence-type service demand of underwater sensor information uplink and the interactive accusation information service demand of surface command center downlink.Starting from multiple communication demands,the subnet is planned reasonably and suitable hybrid network protocols are designed according to the different characteristics of various classical MAC layer protocols.The network protocols are switched between the low concurrency mode dominated by ALOHA-CS protocol and the high concurrency mode dominated by TDMA protocol in response to the different service volumes of the interactive service subnets.The hybrid protocol can balance the communication rate and packet loss rate in different network environments.For the periodic and frequent transmission of convergence services,the TDMA protocol is used to converge the sensor uplink information,and the convergence node merges multiple frames of sensing information messages and relays them to the receiver with the ALOHA-NOACK(ALOHA-No Acknowledgment)protocol to maximize the timeliness and reduce the impact on the interactive services.At the same time,in order to avoid interference between different types of services,each subnet uses different spreading codes in a CDMA(Code Division Multiple Access)manner to reduce inter-subnet communication interference.Finally,the STM32L4 low-power embedded platform is introduced,and the designed network protocol is implemented using C/C++ programming,and the complete network communication implementation process is given by the program flowchart.And the on-lake test is conducted in Danjiangkou to verify the designed network protocol.