Research On P2P Algorithm Under Vehicular Ad Hoc Network

Vehicular ad hoc network is a special kind of MANET(Mobile ad hoc Network),which enables the drivers in the vehicles to get information within the communication range of vehicular ad hoc network, such as the speed of vehicular nodes and whether the traffic on the roads is heavy or not and so on. Thus, it helps to prevent accidents due to lack of information to a large extent. Meanwhile, because of dynamic topology and the frequent disconnection, the efficiency of many communication protocols which performs well in wired network cannot perform well in the vehicular scenario.In order to solve the problems presented above, the thesis briefly introduces the background of vehicular ad hoc network and P2P network, basic concepts as well as practical application scenarios at first, which follows the survey of the current research situation of the combination of vehicular ad hoc network and the analysis of some vital algorithms as well as the presentation of their merits and drawbacks. After the brief introduction of Chord which typifies the structured P2P network, the redundant query algorithm of Chord has been analyzed. The algorithm has proposed that the requester nodes should send n queries to n nodes simultaneously instead of sending only1query in order to solve the problem of frequent packet dropping under the scenario of dynamic topology of vehicular ad hoc network. The simulation result proves that the algorithm enhance the hit ratio and reduce the search latency. However, the algorithm has only taken the fixed number of redundant queries, which cannot be determined according to the real communication situation between the sending nodes and receiving nodes. Therefore, this thesis has proposed a new algorithm to dynamically control the number of redundant queries. The simulation platform of NS-2has been used to perform simulation and analysis after the setup of appropriate network simulation scenario. The results have proved that the algorithm can effectively enhance the performance of the experiment in terms of the hit ratio, the number of packets as well as the search latency.In addition, this thesis has introduced some functions and the algorithms of the vehicular logistic device which is developed by me. The functions include audio broadcasting, emergency calling, Text To Speech (TTS),fatigue driving alarming, calculation of the traveling distance, the query and connection of the goods’information as well as the encryption of data packets. The device is developed based on the development board of mini2440and takes Linux as the operation system. Through the design and the implementation of the system, a good platform to test the combination of vehicular ad hoc network and P2P network in practical scenarios has been presented.