Trusted And Cooperative Routing Algorithms In Mobile Ad Hoc Networks

Mobile Ad hoc networks are the collection of wireless mobile hosts forming a temporary, self-organized network without the help of any centralized administration or standard support services. In such an environment, it may be necessary for one mobile host to enlist the aid of others in forwarding a packet to its destination, due to the limited propagation range of each mobile host’s wireless transmission. It is not limited by the time and space to build quickly and conveniently, so that a MANET is attractive for applications such as disaster relief, emergency operations, military service, maritime communications, vehicle networks, casual meetings, campus networks, robot networks, and so on. There are most salient characteristics of wireless communication, including dynamic topology, multi-hop forwarding, share channel, bandwidth-limited and energy-limited for Ad hoc networks. Similar to conventional fixed networks, security of the Ad hoc networks is considered from the attributes such as availability, confidentiality, integrity, authentication, non-repudiation, access control and usage control. But security approaches used for the fixed networks are not feasible due to the salient characteristics of Ad hoc networks. New security mechanisms are needed to adapt the special characteristics of Ad hoc networks.Traditional MANET routing protocols assume that all nodes in the network work in a benevolent and cooperative manner and no predefined trust exists between communication partners. This may render the network vulnerable to malicious attacks in case of the presence of selfish and malicious nodes. Selfish nodes are those which, in order to save their own batteries, do not propagate packets from other nodes as perform protocol, while malicious nodes may perform impersonation, fabrication or modification attacks against the network traffic. Therefore, to design a routing that can defend malicious or selfish attacks and improve network performance is also one of challenging issues in current research.In view of the two attacks (malicious and selfish attacks) and the researches on hard security for routing, this thesis focuses on the soft security researches, especially on trusted routing and cooperative routing. The trusted routing is usually discussed on the malicious attacks, whereas, the cooperative routing is referred to the selfish attacks.Although there are numerous existing works related to the trusted and cooperative routing approaches, as far as we know, none of them incorporate the characteristics of trust relationship of nodes into Ad hoc networks completely, as well as incentive cooperation of the network. This thesis suggests five respects to improve routing protocol in terms of security and forwarding efficiency.The first three solutions are proposed to avoid and mitigate the malicious behaviors, and the last two solutions are given to stimulate the selfish behaviors. The main contributions of this thesis are as follows:(1) This thesis proposes a trust model based on relationship maturity among nodes (termed as TRM).Due to the absence of defending the malicious recommendation and dynamic updating of trust relationship of nodes, this thesis proposes a new trust model and management mechanism based on the relationship maturity among nodes. The proposed trust model also evaluates the trust level of nodes from the direct trust and recommended trust aspects. The direct trust is calculated by monitoring the neighbor nodes’forwarding behavior, whereas, the recommended trust is computed by selecting the higher the relationship maturity to enhance the precise and timeliness of the trust model. Then, a trust management mechanism based on the trust model is proposed in details so as to improve the effectiveness of initializing, calculating, judging and updating the trust level. The whole trust management mechanism can mitigate the malicious attack and enhance the security assurance. At last, the trust model and mechanism is extended in classic routing AODV protocol to verify the correctness and effectiveness by using NS2 software.(2) This thesis proposes a trusted QoS routing algorithm (termed as TRQ).In the light of the existing works on QoS routing issues, the relevant research related to combine trust model with QoS issue is rarely scarce. This thesis takes the two issues into for consideration to propose a trusted routing based on QoS parameter. Although the multi-dimensional QoS parameters (including throughput, latency, jitter, cost, and so on) are NP-hard problem, this thesis only considers the latency parameter due to the unstable and unreliable wireless link, and design a new metric to integrate the trust level of each node with the transmission latency of each link. During the routing establishing phase, each node can judge the trust level of its neighbor nodes with the trust threshold of network to identify their behaviors, then the higher trust level of neighbor node and minimum transmission latency of the corresponding link can be chosen, so as to satisfy the network security and QoS requirement. At last, this thesis verifies the correctness and effectiveness of the routing algorithm (called TRQ algorithm) by using NS2 software, and compare its performance with classic QoS routing protocol (called QAODV).Results show that TRQ algorithm outperform the classic QAODV in several aspects.(3) This thesis proposes a trusted opportunistic routing algorithm (termed as MCOR).Recently, opportunistic routing has received much attention as a new design direction. It can exploit the wireless broadcast and more highly reliable opportunistic forwarding, so as to substantially increase the throughput of network. This thesis incorporates the concept of trust to Ad hoc networks and builds a simple trust model into opportunistic routing to evaluate neighbors’ forwarding behavior. A new trusted opportunistic forwarding model is proposed by choosing the trusted and highest priority candidate forwarder, then a trusted minimum cost routing algorithm (MCOR) is formally formulated, the correctness and effectiveness of this algorithm from theoretical analysis is also approved.Finally, MCOR algorithm is verified by simulation using nsclick software and compared its performance with the classic ExOR. The simulation results show that MCOR scheme can detect and mitigate node misbehavior.Furthermore, MCOR algorithm outperforms ExOR in terms of performance parameters.(4) This thesis proposes a incentive-cooperative model based on punishment constraint.Combining the idea of classic game theory, this thesis firstly proposes one-step game model to analyze the payoff matrix between neighbor nodes, and then extends the model to a infinite-repeated game on cooperated forwarding packets to enhance the collaboration behavior, and illustrates three punishment strategies towards behavior of selfish nodes (one-step punishment strategy, severe punishment strategy and general punishment strategy), derives the corresponding incentive cooperation forwarding conditions. Nevertheless, this thesis mainly takes into the general punishment mechanism for consideration. Finally, to verify the correctness and effectiveness of the scheme and mechanism mentioned above, this paper implements this scheme and compares its performance with classic AODV protocol by using NS2, moreover, displays the evolving process of utilities of different selfish nodes during the simulation time. Simulation results show that this scheme can enhance cooperation effectively, improve throughput among the nodes, prolong the lifetime of the network and increase the expected total payoff of all nodes.(5) This thesis proposes a secure incentive-cooperative algorithm (termed as ICTP) based on a strategy-proof payment model.In view of the hottest issue of algorithmic mechanism design of game theory, this thesis analyzes the Ad Hoc-VCG payment model based on algorithmic mechanism design, point out the existing main problems of this payment model, propose a strategy-proof and collusion-resistant payment model and design an algorithm called ICTP, which consists of two procedures:routing establishment and data packets forwarding. At last, this thesis verifies the effectiveness and correctness of this algorithm by simulation using NS2 software, compare its performance with other classical algorithms:Ad Hoc-VCG, COMMIT, LMOCP. Simulation results show that ICTP outperforms better than the other algorithms.To sum up, the five solutions mentioned above can be further extended and improved in the other unicast and multicast routing protocols of Ad hoc networks. Furthermore, this thesis proposes some ideas to solve the routing security problems, the research achievements will provide theoretical guidance for the development and applications of Ad hoc networks.