Research On Network Coding Technology In Underwater Acoustic Networks

At present underwater acoustic communication networks has been applied widely in the area of detection of ocean and pollution treatment and prevention of disaster forecast and military operations.Underwater acoustical communication has bad characteristics of low transmission speed,long delay and etc.In this paper,we use network coding technology in underwater acoustical environment,and simulate NCR(Network Coding Routing)protocol.The result is that the network performance has been improved.Not only the packet delivery ratio is increased but also the packet delivery average delay is reduced.Firstly,we discuss the basic theory of network coding algorithm.The main contents include they are:(1)The principle and the construction method of the linear network coding;(2)The construction method of the random network coding and the decoding scheme and conditions.The application of random network coding in NCR protocol is nodes code and forward and decode data.Secondly,we simulate NCR protocol in a circular network topology and a grid network topology.Then we look at the performance metrics included Packet Delivery Ratio,Packet Delivery Average Delay,Protocol Overhead,and Collision Ratio.It shows the impact of NCR protocol on the packet delivery ratio corresponds to 50%~120% improvement.On the other hand,in the large network which there are many nodes the average delay and collision ratio is both decreased.Finally,we propose a timing scheme and pseudo broadcast scheme in network coding.A new timing strategy is insert a waiting time before coding so that nodes have richer packet combination.Timing scheme improves the packet delivery ratio and helps in reducing the average delay and protocol overhead.With the use of pseudo broadcast scheme,the node need to reply confirmation.It ensured there is at least one node receives a packet of data.At the same time,it improve the reliability of data transmission.Through the simulation of NCR protocol and improved NCR protocol in different topology structure and comparison in the results,it presents network coding protocol promote the packet delivery ratio obviously.In the structure of the numbers of nodes reduces the delay and collision ratio of data transmission effectively.