Research On The Key Technologies Of MANET Survivability

Mobile Ad Hoc network has irreplaceable application potential in the field of military, disaster relief, industrial detection, business and etc. Nevertheless, the application environment is rather severe while the network node is fragile. Therefore, higher request and challenge has been raised upon the design of mobile Ad Hoc network. In order to assure the reliable application of mobile Ad Hoc network, a number of researchers have attached importance to the survivability study. This thesis discusses a certain key technologies on the survivabilty issue of mobile Ad Hoc network, and the main contributions and innovative achievements are as follows:(1) Based on the analysis of survivability theory on traditional information system, this paper put forward an important index named DRUA (the packet delivery rate when MANET is under attack) to evaluate the MANET survivability, and also provided an evaluation formula for this index which based on the theory of space probability. After analyzing the formula, it shows that the activity of node and attacking degree will affect the index of DRUA. To further analyze these factors, some experiments were implemented using NS2simulation tools. In these experiments, MANET is under different attacking modes and degrees. The result shows that when the number of CBR flows is comparatively small, random attacking attacking has little negative effect on the performance of MANET. On the contrary, when there are a large number of CBR flows in the case of large-scale MANET, random attacking can greatly influence the performance of MANET in a negative way. This means the evaluation formula is more suitable for large-scale MANET. In addition, randomly attacking neighbor nodes can reduce the performance obviously even when there are a small number of CBR flows.(2) As the performance of MANET with traditional route method falls obviously when it is under attack, a novel STHR route strategy which integrates MANET and DTN routing methods aiming at high survivability was proposed in this paper. And for reducing the total network routing cost especially in DTN routing phase, the method of choosing survivability enhanced nodes has been designed. Those nodes which coved the zone are chosen in charge of both MANET and DTN routing. By this way, it not only ensures rapid DTN routing diffusion, but also reduces the network resource consumption.(3) As the stability of packet transmission in large scale MANET with traditional route method falls obviously, a novel ADHR route strategy which integrates AODV and Spay and Waiter protocols was proposed in this paper. In the range of AODV search extending ring, it still executes traditional AODV route protocol. But out of the range, which the source node and the destination are too far away from each other, the Spay&Waiter protocol begins to work. By this way, the performance of MANET becomes stable even extending the network scale.(4) To restrict the routing cost in lage scale DTN network, this paper design a novel routing strategy named as DRBC which is based on clustering method. Those nodes which have high contact probability with most of other cluster-inner nodes are chosen as cluster heads. Date duplications are diffused between cluster heads and gateways as possiblely as they can. By this way, it can not only reduce the number of duplications, but also not increase the transimisson delay. In addition, to avoid the information synchronization problem in tranditional clustering, DRBC uses the spray and wait transmission method to reduce the requirement on accuracy of cluster head and gateway information. At the same time, it can reduce the difficulty of clustering maintenance.(5) To solve the problem of unstable transmission performance with one path in traditional MANET, this paper established a model of data transmission in MANET, and found that sending data on multi-path at the same time can improve transmission reliability. And this paper designed a multi-path transmission protocol which named MTP based on AOMDV. By simulation on ns2, the multi-path transmission method has been validated.