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An ad hoc network is a kind of wireless communication network which does not rely on a fixed infrastructure and thus lacks in centralized control. Networks of this kind are based on the fundamental assumption that all the nodes would cooperate and not cheat. This assumption becomes invalid in the situation that compromised or malicious nodes exist. In this paper, we propose a Bayesian network-based trust model and a method for building trust based on the recommendations from other nodes and the node’s own experiences. The model is suitable for ad hoc network without a dedicated trust infrastructure or pre-configuration of nodes. Trusted route can be easily found out and malicious nodes can be circumvented by using the trust model.

Multimedia applications present new challenges to the current networking technology. One of them is Quality of Service (QoS) requirement. Due to the increasing dynamics of traffic introduced by multimedia applications, dynamic and flexible QoS (Quality of Service) control is needed to ensure both QoS satisfaction and resource efficiency. Because integrated service networks are designed to support a wide range of traffic classes, which have different service requirements, developing metrics to evaluate them is complex. In this paper there are presented the results of some tests performed on Cisco routers in a quality of service environment.

The definition and relative theories of disjoint paths with QoS constraints were summarized, the model of disjoint optimal paths with QoS constraints problem was illustrated. current disjoint paths algorithm were analyzed, at last the direction for future study and problem existed of disjoint paths algorithm with QoS constraints were put forward.

Considering the limited energy and transmission range of sensor nodes in sensor networks, a tree-based energy-efficient routing algorithm is discussed. According to maximum residual energy of nodes, a tree whose root is the sink node was set up in the covered field in which nodes with maximum residual energy less than ɛ are leaves. And a reliable routing algorithm is used when there have nodes death in the transmitting process. To optimize the algorithm, we use the β-constraint, which puts a soft limit on the maximum number of children a node can have in a tree. It can achieve lower latency and more energy-efficient, and the lifetime of the network is prolonged.

The QoS routing is a hot issue in research, among which the QoS multi-constraint routing is a difficult problem. Pointing out a weak point in the H_MCOP algorithm, the author successfully applies geometric series and binary search algorithm to it, and gets a heuristic routing algorithm of the QoS multi-constrained routing. And the author makes simulation based on NS2, the results of which indicate that this algorithm can find a low cost path and the calculation costs to find the path is low too.

The issue of routing is vitally important in Wireless Mesh Networks. But currently, most routing protocols such as OLSR and AODV cannot make the most of multiple paths between the source site and destination site because of the complexity and the cost. Software Defined Networking(SDN) structure promises to obtain the network configuration effectively, and with a centralized controller, it can deploy fine-grained routing algorithms to make full use of the network resources, while ensuring that the control overhead is acceptable. In this paper, we propose a new approach of SDN-based routing algorithm, or SDNR. We introduce link saturation to SDN, with which the SDN controller can figure out the congested path and reroute the following traffic to another non-congested path, which is the real-time optimal one, to ensure the network throughput. We compare SDNR to classic routing protocols and demonstrate its superiority.

Optimizing routing paths improves the network's topological properties and performance, and helps balance the network's energy. Traditional network routing algorithms use the energy balanced ring routing algorithm, which causes an uneven consumption of energy throughout the network. This paper thus proposes a method of optimizing network routing paths based on an improved ant colony algorithm with constraint feedback. First, a network model is designed, and its topology is established. The robust coefficients are determined, and route choices are used to update the GRAEB routing algorithm. Using the region segmentation method, the confidence interval of cluster routing task's random distribution is obtained. Through the ant feedback constraint, the probability of information being correctly transmitted is increased. According to Bayes' theorem, route node localization and saving of route location reliability recursive algorithm, network routing is optimized. Simulation experiments show that the algorithm can effectively increase the probability of information being transmitted correctly on the network, with transmission being almost distortion-free. As the number of routing hops increases, the advantages of this routing algorithm become more apparent, improving the quality of the information transmission.

Now, the dynamic solution is put forward for the QoS of network service problems, the solution is to integrate the mixture of differential evolutionary algorithm and ant colony algorithm into the QoS routing, and the solution adjusts the local pheromone updating strategy dynamically. The optimal global pheromone improves the global convergence of the algorithm. The simulation results show that DE-ACO algorithm is effective to deal with the problem of routing. At the same time, DE-ACO algorithm compares with the traditional QoS multicast routing algorithm in convergence and convergence speed. DE-ACO algorithm has been greatly improved.