Research On Key Techniques Of Ad Hoc Network Based On The Complexity Theory

Mobile Ad hoc network is a kind of no fixed infrastructure in wireless self-organizing, self-healing networks, the nodes in the network can move in any direction. Therefore, the topology of network is dynamic change. Because the network has distributivity, dynamic, autonomy nature, mobility and isomerism, so it can be applied to many special occasions, such as mobile data exchange, battlefield communications systems, portable computer and communication.Routing is the key technique of Ad hoc network and one of the most important factors affect the performance of the network, therefore, the study of routing protocols becomes hot spots now. However, the self-organizing of wireless network, the dynamic changes of network topology, the limit of network resources and the bad application environment make the traditional wired network routing protocols are no longer applies to the wireless mobile Ad hoc networks, and make the network nodes invalid easily because of energy depletion or damage arising from the natural world, which destroy network communication directly or indirectly, which make the design of the routing protocol of the Ad hoc network becomes more complex, it gives the researchers of routing protocol a new challenge.From the complex network theory, random attack and intention attack can cause the invalidation of nodes, in order to strengthen the network of random attack and intention attack on the network robustness and make use of the limited resources. In this paper, in order to improve the protocol of the Ad hoc, the main jobs of this paper are as follows:First, this paper studied the Ad hoc network routing protocol in detail, understood the routing algorithm and the working principle of the routing protocol, and compared the advantages and disadvantages of the existing routing protocols and the major problems of the current routing protocols facing.Second, combined with the small-world and scale-free characteristics of complex network, put forward a threshold function which was applied to the Ad hoc network protocol, put forward an Ad hoc routing protocol, which was based on the complex network theory.Third, this paper researched the proposed routing protocol which made when the nodes select the next hop are not flooding broadcast messages, but in the right of the neighbor nodes transmit power P, the load L and the dump energy E to calculate the threshold, according to the threshold to select the next hop node. Not only be enable its to overcome the flooding broadcast, but also to reduce the packet loss and delay increasing because of the overload of the nodes. When the serial number is same, it can avoid to network load at more concentrated on some road as a result of selecting few routing hops, but not to make use of the lighter load, at the same time ,it can enhance the network robustness.Fourth, in order to verify new protocol on the network to have better robustness, this paper designed the methods of network attack, and added them to the new protocol.Finally, NS2 software was used to simulate the new protocol, its simulation was under network subjected to random attack and intention attack. The results proved that the new routing protocol made the network have better robustness under network subjected to random attack and intention attack and reduce the end-to-end delay.The main innovation points of this paper are as follows:First, according to the small-world and the scale-free properties of the complex network, put forward a threshold function.Second, put forward the methods of network subjected to random attack and intention attack.Finally, the threshold function and the attacking methods ware applied to the Ad hoc network routing protocol, to enhance the network robustness and reduce end-to-end delay.