Research,Implementation And Verification Of Typical Application-Oriented Underwater Acoustic Network System Architecture

The oceans cover two-thirds of the Earth’s surface.In-depth exploration and study of oceans is of great importance to human development.Establishing the Underwater Internet of Things(UIo T)and ultimately achieving interconnection,information sharing,and cooperative operation among heterogeneous underwater intelligent devices is a pressing global challenges.Compared with other underwater communication methods,underwater acoustic communication is widely recognized as a suitable and cost-effective means for medium to longrange communication.The maturing Underwater Acoustic Communication(UAC)technology has laid the foundation for developing Underwater Acoustic Networking(UAN)technology,an essential component of ocean information systems that enables the interconnection of underwater intelligent devices.Underwater acoustic networks are complex distributed systems comprising multiple underwater nodes connected by underwater acoustic channels.These networks achieve system capabilities such as multi-node real-time access,dynamic route optimization,and reliable data transmission through the design of system architectures and network protocols.However,the complex marine environment poses significant challenges to underwater acoustic channels,which exhibit characteristics such as narrow bandwidth,long delays,multipath propagation,high Doppler effects,high error rates,and half-duplex operation.These challenges necessitate unique system architecture and protocol design for underwater acoustic networks,as the architectures and protocols from terrestrial wireless networks are not directly applicable.Therefore,it is crucial to research and construct underwater acoustic network system architectures and protocols suitable for underwater application scenarios.This doctoral dissertation undertakes a significant research endeavor,implementation,and validating underwater acoustic network system architectures for three distinct network scenarios.These scenarios include centralized small-scale networking,complex large-scale heterogeneous node networking,and remote high-speed bidirectional networking.The dissertation identifies three unique challenges,designs three different underwater acoustic network architectures,and implements and validates the effectiveness of these three network systems in real marine environments.The dissertation’s main contributions are as follows:First,in response to the centralized small-scale underwater acoustic networking application scenario,an Underwater Wi-Fi Network(uw-Wi Fi)system that utilizes a masterslave mode architecture is proposed in this dissertation.uw-Wi Fi consists of a base-station node(on the surface or underwater)and a small number of terminal nodes(usually less than 5),with each terminal node establishing a communication link rapidly with the base-station node through underwater acoustic communication.The network can achieve functions such as data collection and collaborative operations.Compared to terrestrial wireless channels,underwater acoustic channels feature long delays,high error rates,and half-duplex operation,which make it challenging to directly transplant terrestrial Wi-Fi network’s multiple access control and reliable transmission protocols to uw-Wi Fi.This dissertation considers the master-slave network architecture and the characteristics of the underwater acoustic channel,and designs a time Sequence-based Dynamic on-Demand Assignment(SDDA)MAC protocol to address the issue of terminal nodes sharing network communication resources.Additionally,a Data-driven Adaptive Reliable Transmission(DART)algorithm is proposed,allowing different types of application data in the network to dynamically adopt different reliable transmission mechanisms based on the network state.This dissertation implements an actual uw-Wi Fi network system and conducts shallow-water and deep-sea experiments.The experimental results indicate that in real marine environments,the throughput of uw-Wi Fi can reach 500 bps.And it can operate stably for over 30 days under deep-sea conditions.Second,in response to the complex,large-scale,and heterogeneous networking scenarios,an Underwater Cellular Network(uw-Cellular)system based on hierarchical architecture is proposed in this dissertation.uw-Cellular consists of two levels of networks: the first level network is composed of a gateway node and several(generally not more than 4)second-level network base station nodes;each second-level network consists of a base station node and a small number of heterogeneous terminal nodes,forming the uw-Wi Fi network.This dissertation designs an adaptive hierarchical cross-layer optimized MAC protocol based on time-division scheduling to address challenges such as a large node number,wide coverage area,and dynamic node access in uw-Cellular.This protocol integrates the advantages of time-division scheduling,channel reservation,and cross-layer mechanisms to solve the issue of channel resource sharing in the two-level network.Additionally,a Communication Link Awareness(CLA)routing protocol is proposed,which quantifies communication link states and cross-layer data sharing to dynamically optimize the selection of data forwarding links,effectively addressing issues related to mobile terminal node access and inter-network switching.This dissertation implemented the uw-Cellular network system and conducted sea trials with a 20-node network.The coverage area of the network exceeds 100 km2.Experimental results indicate that under moderate hydrological conditions,the throughput of uw-Cellular can reach 550 bps,with a network data delivery rate of no less than 78%.Third,in response to the remote high-speed bidirectional scenarios,an Underwater Backbone Network(uw-Backbone)system is proposed in this dissertation.The uw-Backbone consists of a gateway,a terminal,and several relay nodes.The terminal node can access the backbone network through any relay node,transmitting data to the gateway node through multihop relays.Due to the spatiotemporal complexity of the underwater acoustic channel,as the number of relay nodes increases,uw-Backbone faces significant challenges in data transmission reliability.This dissertation designs a data-concurrent-based adaptive time-division MAC protocol.This protocol effectively improves end-to-end data transmission reliability through methods such as dynamic calculation of forwarding time slots,parallel scheduling of data transmission,and explicit/implicit acknowledgment management for data reception.This dissertation implemented the uw-Backbone network system and conducted sea trials with a 21-node(20-hop)network.Experimental results indicate that the total network communication distance can reach 87 km under fair sea states,with end-to-end communication rates exceeding600 bps.