The Research On Key Technologies Of Trust Routing And Transmission Control In Wireless Sensory Networks

Wireless sensor networks (WSNs) have wide application prospects in terms of national security and all kinds of national economies. It is essential for reliable data transmission to smoothly execute the functions of network and prolong the lifetime of network, which is one of the key issues to be solved for the practical application of WSNs. However, security system based on cryptography can only prevent external attacks, neither design ideas nor implement methods of the system can solve the internal attacks caused by network nodes invalid or compromised. Moreover, it is necessary for reliable data transmission to create a reasonable transmission control method which is aimed to solve packets reliability and losing data packets brought by congestion. Therefore, in order to achieve the trust and reliable data transmission method which is energy efficient in network, it is necessary to make an in-depth research of key technologies of trust routing and transmission control. The research is divided into three parts:(1) The first part researches on the trust evaluation among nodes and the method of efficient routing to achieve the energy efficient network routing based on nodes'trust. (2) The second part researches on cross-layer active predictive data transmission control methods to solve network congestion and data error, as well as improve the overall performance of network. (3) The final part researches on building trust evaluation and transmission control experimental platform to verify the validity of the proposed algorithms.Nodes failure or compromised in wireless sensor networks will lead to serious security problems. In this paper, a node behavioral strategies banding belief theory of the trust evaluation algorithm is proposed. According to nodes'behaviors, a variety of trust factors and coefficients of each factor based network application is established to obtain direct and indirect trust values through calculating weighted average of nodes. Meanwhile, the fuzzy set method is applied to form the basic inputting vectors of evidence theory. On the basis, the evidence difference is calculated between indirect trust values and the direct trust values, which links the revised D-S evidence combination rule to finally synthesize integrated trust value of neighbor nodes. Simulation results have shown that the proposed scheme can effectively solve the network problems which are difficult to identify malicious nodes and represent the characteristic of trust value that'hard to acquire and easy to lose', further to ensure the security of WSNs.Reducing energy consumption is essential for the life of wireless sensor networks. A confidence interval banding taboo-level of hierarchical routing algorithm for long-lived sensor network is proposed. Using the fact that the intra-cluster data taking on Gaussian distribution characteristics, the new scheme makes sample data setting confidence interval to compare with the total model, which can be effective in reducing the amount of data being sent. In order to avoid hot collected in cluster, taboo method is used for sampling data to calculate the taboo-level. Simulation results have shown that new shecme can satisfy the desired accuracy given by system and lengthen the life of network significantly better than other similar algorithms.As for the issue of how to choose the trust routing during the data transmission, on the basis of nodes'trust evaluation(Chapter 3) and the research of energy efficient routing(Chapter 4), a hierarchical routing algorithm based on nodes' trust in wireless sensor networks is proposed in this paper. Firstly, the algorithm adopts the new proposed trust evaluation method (Chapter 3) to evaluate and obtain the trust of nodes. Secondly, the trust evaluation algorithm is combined with the density, centrality, and trust of each node to select the backbone of route (cluster head), which is to establish the credibility routing table of each node, at the same time, the new hierarchical routing algorithm(Chapter 4) is used to reduce the internal energy consumption of cluster. Thirdly, according to the distance and related coefficient between cluster heads of network, the proposed scheme determines the data forwarding relationship between cluster heads to further reduce the energy consumption of data transmission. Simulation results have shown that the proposed scheme can achieve the requirements of reliable and energy efficient of network routing, as well as solve the problems of network'perception empty'and 'energy hot spots'.Congestion and data error influence severely the transmission capability and life of wireless sensor networks. A cross-layer active predictive data transmission control protocol for improving network performance is proposed in this paper. According to the cache status of single-node, as well as the average occupancy cache for local network, the proposed scheme adopts queuing theory to analysis data flows, also combined with trends of local network data flow, forecasts and adjusts actively the sending rate of each node at the next time. Whilst, in order to ensure the fairness and timeliness of the network, the protocol has revised competing strategy of MAC according to the original data stream priority, waiting time and still the amount of neighbors, which can adjust dynamically the sending priority of each node. The simulation results have shown that the proposed scheme can effectively ensure the reliable of data transmission. Furthermore, it has outstanding performance in terms of reducing packet loss ratio, transmission delays, the fairness of transmission, as well as power consumption of network.In order to verify the validity of the proposed algorithms, trust evaluation and transmission control experiment system for wireless sensor networks is designed. Firstly, we introduce hardware equipments that are independent developed by our laboratory, including N201 series of sensor nodes and gateways. Secondly, we describe the overall structure of the system and focus on illustrating program designing of nodes and gateways based on the NesC language, as well as the implementation details of TestBed management software. Finally, the performance of trust evaluation and transmission control system is tested by experiments. The system has versatility and expandability, which can not only provide validation and testing platform for the study of trust evaluation and transmission control algorithms, but also lay the basis for other applications and researches of wireless sensor networks.