The Research Of The Underwater Handshake Competitive MAC Protocol Based On Space-time Characteristics

Underwater acoustic sensor networks(UASNs)are the research hotspots in the fields of marine development,environmental monitoring and military reconnaissance.As one of the core technologies of the UASNs,the media access control(MAC)technology is mainly responsible for the allocation of channel resources to avoid collisions when data packets are transmitted.However,the underwater acoustic channel has the characteristics of long propagation delay,high bit error rate,narrow available bandwidth,multipath and Doppler effect,which brings difficulties and challenges to the study of the underwater MAC protocols.Therefore,how to design a stable and efficient MAC protocol is essential for the characteristics of the underwater acoustic channel.Based on the National Natural Science Foundation of China,this thesis focuses on the MAC protocol of the UASNs.The underwater handshake competitive MAC protocols based on space-time characteristics are proposed,and the simulation experiments and performance analysis are carried out.The main research contents include:1)Based on the summary of the design ideas,advantages and disadvantages of the existing underwater MAC protocol,the basic principles of the typical competitive MAC protocols are introduced.Based on OPNET network simulation software,a long-distance deployment model of the UASNs is built.Then the simulation and performance analysis are carried out,which lays a foundation for the improvement mechanism of the subsequent research.2)Aiming at the applicability of the space-time reuse mechanism in the long-distance deployment of underwater scenario,a Spatial Reuse based Handshake-Competition MAC Protocol for Underwater Acoustic Networks(SR-MAC)has been proposed.The protocol allows multiple nodes to simultaneously access the channel through a parallel transmission mechanism,thereby implementing multi-node data transmission in one handshake period,which realizes the spatial reuse of the channel.Through the Request to Send(RTS)competition algorithm,the node access channel unfair phenomenon caused by the underwater space-time uncertainty is improved.The simulation results show that compared with the typical protocol,the SR-MAC protocol can improve network performance to a large extent.3)In order to improve the channel utilization of the non-slot MAC protocol DACAP,a Time Planning based Handshake-Competition MAC Protocol for UASNs(TP-MAC)is proposed which makes the traditional handshake mechanism improved.The mutual transmission mechanism is implemented to realize the opposite transmission of data.If the mutual transmission mechanism is not applicable,the node random access mechanism allows the node in idle state to access the channel according to probability.Thereby,the channel utilization rate is improved.At the same time,the reasonable handshake interval is planned through the transmission protection mechanism after each handshake,which enhances the robustness of the protocol.The simulation results show that the TP-MAC protocol can effectively improve network performance compared to the typical competitive MAC protocols.