Research Of Cooperation In Ad Hoc Networks Based On Hellinger Distance

Mobile Ad hoc Networks (MANET) is a temporary self-government network system which consists of a collection of mobile nodes with wireless transceivers. It has multi-hop and dynamic characteristics without fixed base stations and central server, so it will be a necessary complement and expansion for existing computer communication networks. Each node acts not only as a host but also a router. MANET should rely on the cooperation of mobile nodes in all network functions (routing and packet forwarding). As a result of these network functions need to consume a large amount of energy, memory, bandwidth, and other resources, some selfish or malicious nodes in order to save their own resources without the participation and cooperation. Cooperation among nodes is a prominent and special issue in MANET.In this paper, cooperation faced in MANET has been deeply analyzed and investigated. It analyzes the selfish behaviors of nodes which refuse to forward data packets and routing packets for other nodes on the performance of the whole networks such as packet ratio and jitter through the simulation experiments based on NS2, and indicates that selfish type 1 and selfish type 2 are the main manifestations about lack of cooperation in MANET. So the guarantee of cooperation is the basic needs in Ad hoc networks. At present, domestic and foreign research institutes and scholars make some preliminary solutions. According to the mechanism of its realization, it could be divided into two types: reactive scheme (detect of behavior, such as Watchdog mechanism and 2ACK mechanism) and preventive scheme (incentive of behavior, such as credit-based method,reputation-based method and game theory method).The existing detect schemes are lack of accuracy and cannot adapt the whole routing stage. With the characteristics of distance measure, an algorithm of detection and punishment based on the distance is proposed. This paper introduces definitions and properties of some typical distance algorithms and gives their performance analysis. Experimental results show that Hellinger distance algorithm is a fully measure which has advantage in the detection accuracy, time spent, the algorithm complexity, and so on. So it is more suitable for cooperation detection scheme. After solving the key techniques such as the choice of eigenvector, calculation and update of Hellinger distance, the choice of threshold and so on, it designs the detection and punishment algorithm based on the Hellinger distance in detail. The simulation results based on NS2 show that the algorithm can detect different types of selfish activities effectively, and promote cooperation between the nodes. And performance evaluation shows that the algorithm makes up the disadvantage of inaccuracy in existing detection schemes and it adapts the whole routing stage while improving the performance of MANET.