Research On Trust Evaluation Models And Methods For Wireless Sensor Network

Due to the low power consumption, low cost and ability of independent awareness, data storage, processing and wireless communication, Wireless Sensor Network has been widely used in military, agriculture, health, environment and other various aspects. But the sensor nodes of WSN are usually deployed in the open environment, and the computing, storage, bandwidth and energy resources are limited, thus the sensor nodes are vulnerable to capture and this may lead to a serious threat to network security. As a result, the safety and reliability of data transmission in wireless sensor network is very important. The traditional cryptosystem can only handle the external attack but do nothing to the internal attack. With the use of trust evaluation mechanism we can distinguish the malicious nodes from the normal ones and effectively prevent internal attack caused by node capturing, which is of significant importance to guarantee the network security and improve the network performance.In order to establish credible and efficient data transmission environment, and smoothly execute the function of network, it is necessary to make an in-depth research in trust evaluation and hierarchical routing. Based on the analysis of the wireless sensor network security problems and related technology research status, trust evaluation of sensor node has been proposed from perspective of node reliability, which can be used to eliminate malicious nodes and improve the network performance. The main work of this paper includes the following two parts:(1)The design of the wireless sensor network node trust evaluation model and calculation method for node trust value assessment. It is used to distinguish the normal nodes and malicious nodes by the final trust value computed by monitoring data and the recommendation data from the prospective of node trust value.(2)The improvement of traditional LEACH protocol is on the basis of the work mentioned above. Taking the trust value into consideration during both the election of cluster head and cluster formation stage, one can refuse malicious nodes to participate in the network data transmission. Then the design of cluster data transmission with multiple hops mechanism, which is measured by the number of hop count, can balance the network energy load by sending data to the Sink node after hops between cluster head nodes other than sending to the Sink node directly. By this way, one can avoid hastening the death of the cluster head over a long distance due to the large energy loss to send data and prevent isolated malicious cluster head nodes from sending false data directly to the Sink node. So the network lifetime and safety performance of WSN can be improved. In addition, this part of the study is based on LEACH protocol but not limited to LEACH protocol, the improvement can also be extended to other category of hierarchical routing protocols.The result of simulation shows that, we can accurately distinguish between normal nodes and malicious nodes through the node trust value evaluation. Further-more, the improved LEACH protocol can effectively balance energy load of network and improve the lifetime and network performance of WSN.