| Underwater acoustic communication network has the characteristics of limited available bandwidth,long propagation delay,low communication rate and obvious noise interference compared with terrestrial wireless communication networks because of the nature of the unique properties in underwater acoustic media.With the rapid growth of demand in various related fields and industries,the ability of simple point-to-point communication can no longer meet the application needs of industry development.The networking technology of underwater acoustic communication has gradually become a key problem in the application of ocean engineering and related fields.The inherent characteristics of underwater acoustic physics and the growing demand in the application field pose a great challenge to the protocol design of underwater communication network.In the past,the research of underwater acoustic communication network mainly focused on transplanting mature terrestrial wireless communication network technology.However,due to the complexity of underwater acoustic physical environment,this technology transplantation is not effective.In more cases,the analogy transplantation of related technology needs to break the whole perspective of conventional technology in order to achieve better performance.At the same time,facing the emerging new problems in underwater acoustic networks,there are no similar problems on land that can be used for reference by analogy.More breakthroughs require us to look at the problems from the perspective of underwater communication itself and propose innovative solutions.Cognitive radio technology is a relatively mature technology in software defined network technology.By analogy with cognitive radio technology,cognitive acoustics technology has been proposed by researchers of underwater acoustic sensor networks,and the research direction will be devoted to building a spectrum efficient utilization system friendly to underwater artificial acoustics system and underwater biological acoustics system.However,in the face of the special underwater physical environment,the traditional cognitive radio technology provides more application requirements for the realization of such cognitive acoustic system than the direct analogical application of technology.These problems,such as the efficiency and effect of underwater spectrum sensing,the stability and bandwidth of public control channels,need to be solved.This paper presents a design scheme of underwater cognitive acoustics network system,focusing on MAC protocol design,including the following three parts:1)A spectrum sensing method is implemented independently by the receiver,which uses the spectrum sensing results of the receiver and the channel state maintained by limited monitoring information to make joint spectrum decision and power allocation.2)A scalable long propagation delay network scheduling strategy supports unicast,multicast and broadcasting,while providing optimal throughput to meet the monitoring requirements of public control channels in underwater cognitive acoustics networks and the requirements of high throughput conflict-free transmission.3)A new set of hidden terminals and exposed terminals involving spectrum selective absorption,dynamic power allocation and mobility of nodes in multi-hop networks is proposed,which is different from the traditional triple hidden terminals.The underwater cognitive acoustic network system proposed in this paper can meet the networking requirements of large underwater network applications,such as the construction of underwater observation network,underwater cluster mobile detection,underwater geological and meteorological observation data collection,etc.It combines the scalable node topology deployment strategy with the design of underwater media access control protocol.At the same time,new practical design constraints are proposed for power control considerations and media intervention control in underwater acoustic multi-hop networks and mobile ad hoc networks. |
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