Resources Allocation Schedule Of Relay-aided Underwater Acoustic Communication System

With the development of technology,communication technology has been used in every aspect of life.Though wireless communication technique is continuing to mature,underwater communication has hidden potential.Approximately 71%of the Earth's surface is ocean.there are large amounts of resource in the ocean,which is also the wealth of all mankind.Underwater acoustic communication technology is one of the most important tools of exploring the ocean.So to study the underwater acoustic communication technology and optimization schemes is a great developing space.The main work and innovations of this thesis are summarized as follows:Firstly,key techniques of underwater acoustic communication technology are elaborated,which including the basic knowledge of acoustic wave and sonar,the characteristic and model of underwater acoustic channel,especially in shallow sea acoustic channel,the concept of Orthogonal frequency division multiplexing,the types of relay cooperation communication,especially in amplify-and-forward and decode-and-forward project,which lays foundation of following research.Secondly,To improve the quality of underwater acoustic communication system in the complex channel environment,a resources allocation schedule of relay-aided underwater acoustic communication system with ARQ feedback is proposed in this paper..User selection and rate allocation by amplifying and forwarding signal and using feedback information of ACK/NAK(correct decoding/wrong decoding)through relay in consideration of target packet error rate and relatively complicated underwater environment is implemented.Simulation results show that compared with traditional arithmetic,proposed algorithm can obtain lower bit error rate in condition of lower complexity,which means approaching the performance index of known channel information.Thirdly,moment channel state information based optimal power allocation between source and relay.However rapid changing time varying acoustic channel will lead to the outdate of channel state information,which result in the low performance of the whole system.For solving this problem,a channel prediction scheme is applied during the propagating time of the signal In other word,the least square filter is used to predict the upcoming impulse response of acoustic channel.Compared with the scheme of lacking channel prediction,this scheme is better,which conforms the significance of channel prediction.Finally,a new power allocation plan of straight path aided acoustic communication system is researched with amplify-and-forward relay and channel prediction.Moreover diversity combining optimal power allocation between source and relay is inferred,which makes the scheme become more and more universal.