Abstract—In this paper, the researchers have presented a Game Theoretic model for identifying bad or malicious users in a collaborative wireless network. Objective of the malicious users is to damage the collaborative wireless network. To bind the damage caused Game theory provides an inventive mechanism. The proposed approach helps in obtaining optimal wireless network. The model is based on graphical representation and repeated graphical games with incomplete information. The framework is applicable to any general network topology. Index Terms—Collaborative networks, incomplete information, repeated game. I. INTRODUCTION A. Collaborative Wireless Network A wireless network is a flexible data communications system that can use either infrared or radio frequency technology to transmit and receive information over the air. Basic components of a Wireless network are access points (APs), nodes, base stations, Network Interface Cards (NICs), client adapters and server. As wireless network evolve they move towards decentralization in which each node plays multiple roles at different situations without relying on a best station or access points to make decision. It is characterized by distributed, dynamic, self organizing architecture. These characteristics lead to the need of distributed decision that takes into account the network and channel conditions. An individual node may need to have access to control information regarding other nodes actions, network congestion etc. Each node in the network is capable of adopting its actions / operations based on the current environment independently, providing a distributed and dynamic environment for wireless networks. In the absence of centralized control each node is free to choose its actions in a legitimate or selfish or malicious way. For the successful working of network the perfect understanding and collaboration among the users is needed. The term “Collaboration” if defined in terms of following Manuscript received May 21, 2012; revised June 26, 2012. S. U. Purohit is with Department of Mathematics, Kirti College and Department of Technology and Mgmt, NMITD, Mumbai, India (e – mail: supurohit@gmail.com) V. Mahadevan is with Information Systems & eBusiness, Swinburne University of Technology, Melbourne, Australia. (e–mail: vmahadevan@swin.edu.au) S. D. Mantri is with Department of CS & IT, Kirti M. Doongursee College, Mumbai, India .(e - mail: shrutimantri@gmail.com) D. U. Purohit is with Dept. of Applied Mathematics, DIAT (DU), Girinagar, Pune, India (e - mail:devank.purohit@gmail.com) certain protocols and sharing of resources and expenditure incurred on these resources in an environment, the phrase “Collaborative Networks” refers to addressing the issues in such environment. B. Need of Secure Collaborative Wireless Network In dynamic environment users communicate and collaborate with one another with a greater extent. As per the course of action chosen the main three types of network users are: legitimate users, selfish users, malicious or bad users; who work in this collaborative environment. Among them malicious users are motivated and more knowledgeable than the average legitimate users and are always ready to take the advantage of the collaborative environment in which legitimate users work. Any strategy, best practice, or protection mechanism used by the legitimate user is compromised by the malicious ones, and exploited within no time. Hence we need a secure wireless network when it comes to working in collaboration. C. Importance of Game Theory for Wireless Network An ad hoc wireless network is a self-configuring, multihop network in which there is no central authority. Thus, every aspect of the configuration and operation of an ad hoc network is completely distributed. As mentioned before furthermore, nodes are often severely energy and power constrained. In emerging wireless networks, such as sensor networks, mesh networks, and pervasive computing systems, many of these same features - decentralized operation, self configuration, and power/energy awareness - are often desirable. The requirement of dynamic distributed environment of collaborative wireless network is provided by Game theory, which is a study of the interaction of autonomous agents. In a modern wireless network, each node running a distributed protocol must make its own decisions (possibly relying on information from other nodes). These decisions may be constrained by the rules or algorithms of a protocol, but ultimately each node will have some flexibility in setting parameters or changing the mode of operation. These nodes, then work as autonomous agents, making decisions about transmit power, packet forwarding, back off time, and so on. In making these decisions, the node may seek to optimize the following: (a) The “greater good” of the network as a whole (b) Behave selfishly, looking out for only their own user’s interests (c) Behave maliciously, seeking to ruin network performance for other users. In the second and third cases, the application of game theory may be straightforward, as game theory traditionally analyzes situations in which players objectives are in conflict. In the first case, node objectives may be aligned (as all players seek the “greater Game Theoretic Inventive Mechanism for Shielding Collaborative Wireless Network Seema U. Purohit, Venkatesh Mahadevan, Shruti D. Mantri, and Devank. U. Purohit International Journal of Modeling and Optimization, Vol. 2, No. 4, August 2012 554