Research On Mobile Peer-to-Peer Overlay Topology And Cooperation Guarantee Mechanism Of Nodes

With the development of the mobile communication technologies and the popularization of mobile devices, Peer-to-Peer has been applied in various areas including mobile devices and wireless networks. Researchers have focused on the Mobile Peer-to-Peer (MP2P) which is more popular and more distributed. MP2P has many characteristics including the large scale, the self-organization, the complex environment, the limited resources and the highly dynamic topologies. For those characteristics, researches and developments of MP2P are facing new requirements and challenges.At first, P2P network is a distributed overlay network based on Internet. The goal of P2P network is to combine those abilities of various end systems for large scale cooperation and resource sharing. Thus, the overlay topology is very important for the system performance. That is, for such a highly distributed and heterogeneous environment as MP2P, it is the basic and key technology that how to build a good performance overlay topology. The second, there is a basic assumption in P2P network that every peer would like to share its resources. However, because of characteristics including the distribution, the dynamic and the mobility, there are many malicious behaviors such as the free-riding, the Sybil attack, the whitewashing in real P2P networks. There are also the same malicious behaviors in mobile environments as those in P2P networks. And hence, mechanisms for guaranteeing the cooperation among peers are more necessary and in worse need of in MP2P. Therefore, the cooperation guaranteeing mechanisms are one of key technologies for MP2P.The thesis focuses on overlay topology structure and cooperation guaranteeing mechanism of nodes. The main contributions are presented as following:(1) A3D Overlay Based on Information Exchange for MP2P (3D-OBInfoEx) is presented. The structure combines advantages of some overlay structures including the multi-dimension mesh-based topology and the tree-based hierarchy topology. Firstly, the nodes are partitioned into different autonomic systems by the distance. This can guarantee the matching between the physical network and the logic overlay topology. Then the information centers are selected based on the information exchange between nodes. The triple information centers backup each other, and take on different tasks respectively to avoid bottleneck and share the loads. Based on the3D-OBInfoEx, each node can obtain the global view with only local information. The costs used for information updating and processing are low and the system is scalable, fault-tolerant and stable.(2) A punishment and cultivation mechanism for promoting cooperation is presented. The non-cooperation behaviors such as the free-riding, the Sybil attack and the whitewashing are prevented when the topology is constructing and adjusting. The freeriders are punished to be kicked out of the system when there are new nodes to join the system.The Sybil attack nodes and whitewashers are rejected to join by the sytem. Base on above schemas, non-cooperation nodes are punished and cooperation nodes are encouraged, so as to guarantee cooperation nodes to achieve services efficiently. The nodes contribute resource actively to guarantee that the system can self-supervise, self-maintain and self-comply with cooperation rules.The system performance can be improved.(3) It is very important that guaranteeing cooperation between nodes in the MP2P system. Current cooperation researches such as incentive mechanisms, monetary mechanisms and game theory are all based on the classical economics, which regards the players in the system as "complete rational". Differing from above researches, a cooperation guaranteeing mechanism based on altruism punishment is presented. The altruism punishment is wildly observed through a lot of experiments in behavioral economics. It supposes that some nodes have the predisposition to punish selfish nodes called non-cooperator, even though those nodes would receive lower payoffs or nothing. It improves the cooperation level of the system through punishing the non-cooperation nodes, and increases the benefits for the system.The system performance is guaranteed.(4) Three mechanisms including internalization of norms, concludeing alliance and third party intervention are presented to strengthen the capability of the altruism punishment nodes.Mathematic model is introduced to give the condition satisfied by the altruism punishment nodes to guarantee the sytem's completed cooperation. And, it much be known that how do the three mechanisms affect the non-cooperators'punished harms s and the altruism punishment nodes'cost cp of surveillance, so as to affect the cooperation level of system. It is proved that the altruism punishment nodes will try their best to contribute their resource ability to guarantee cooperation, so as to improve the popularization of cooperation behaviors in the system.