The Research And Implementation Of Delay Tolerant Network In Emergency Communication

In the face of severe natural disasters and other emergencies which happenedfrequently, researching and developing an emergency communication system whichis independently of the current communication system is a hotspot of research on thecurrent emergency communication. The system should have these characteristics:portable and deploying rapidly, voice and data communication over long distancefor small part of users, and so on. Emergency communication system can be dividedinto two parts, one is close handheld mobile communication terminal which has thecharacteristic of mobile Ad Hoc network; and the other is satellite communicationwhich is composed of the base station on the ground and synchronous satellite.These two kinds of networks have these characteristics of irregularly disconnection,large time delay, asymmetric rate, the unstable links of communication, therefor thetraditional network structure cannot meet the need of emergency communications.So delay tolerant network is put forward, which can largely alleviate these problems.The key technology of structure of delay tolerant network is the Bundle layer,the functions of custody transfer and store-forward are provided by the Bundle layer.These two functions can improve the delivery ratio of data, and also indirectlyensure the end-to-end reliability. Because of the advantages of DTN structure, it isnow widely used in the deep space communications, military communication andsensor networks, and so on.Routing algorithm can also affect the performance of delay tolerant network,and it is the necessary step to research the performance of network. According to thecharacteristics of different networks and using different routing algorithm canlargely improve the quality of the network. The main research objects of this paperare the ground mobile Ad Hoc network and satellite communications network.Through the analysis of the characteristics of Ad Hoc network, this paper adopts theEpidemic and PROPHET routing algorithm, this two are random routing algorithm.The node which randomly mobile in the network cannot establish a path between thesource and the destination, and only can randomly or purposefully transmit data orpackets to neighbor nodes around the node. Link-state routing algorithm anddistance vector routing algorithm are adopted in satellite communication, these are mainly because the satellite communication network topology is predictable, butbecause of the bad weather conditions, such as natural body sunscreen, the link willbe disconnected.The node’s energy consumption, storage space, link bandwidth and overload inmobile Ad Hoc network are constrained. And transmitting the data to thesurrounding neighbor nodes with the random routing algorithm is a big waste ofresources. So in this paper, the Epidemic algorithm will be improved about theenergy of the nodes; and PROPHET is also improved from delay and jitter.This paper adopts the NS2simulation software to achieve these goals, theestablishment of the DTN structure, writing routing algorithm, setting up thesimulation scenes, and then analyzed the simulation results of experiment. Theresults will prove that the DTN structure can further ensure the quality oftransmission of data even under the poor condition of the network.