Study On Routing Protocols And Security For Network Layer In Wireless Sensor Networks

Technology advances in micro-processors, memories and wireless communications has led to the emergence of micro sensors which are small in size and low-cost. These wireless senor nodes have the capabilities of sensing, data processing and communication. They collaborate with each other and leverage the idea of Wireless Sensor Networks (WSN) in a self-organized way. Generally, a sensor node is responsible for sensing data from the monitored objects, doing some simple computation locally and sending the partially processed data back to the observers for the services such as data querying and statistic. WSN can be deployed into the unmanned area, and so it has a wide range of applications, such as environment preservation, disaster forecasting, precision agriculture, traffic control, and military. Nowadays, the academic community shows great interests in WSN because it has become a significant problem relating to our daily life and production.For the reasons that the sensor energy cannot be regenerated and the communication bandwidth, memory and computing powers are extremely limited, the traditional technologies for Internet cannot be migrated to WSN. Ad Hoc networks are also different essentially from WSN in the directions of energy supply, computing power on node. Therefore, a new architecture especially for WSN should be established. Most research work are concentrated on commutation protocols, security and reliability, testing platform and tools, data management, node location and topology discovery, hardware system and so on.The main task of the network layer in WSN architecture is to implement multi-hop routing for data transmission. The hard limitations of sensor energy and other resources require that the routing algorithms should be simple and need a low volume of information and communication. However. the open wireless channel and the unmanned working style make it a great challenge to the security of WSN. Attacks at the routing layer can result in information interruption and sophistication, node isolation, and even worse network paralysis. Therefore, it is quite necessary to presents the routing protocols with intrusion resistance and security guarantee.This dissertation introduces the basic concepts and typical applications of WSN first. Then, based on the deep analysis on the existing routing protocols and their security problems, it suggests the framework for security research in routing layer. According to the security framework in routing layer, a certainty-based secure routing protocol CBSR is proposed. CBSR takes the certainty as reference to choose keys, and adjusts the length of keys along with the computation complexity dynamically. CBSR solves the problem of providing different security levels for different applications. Based on the idea of clustered routing, the security protocol with intrusion detection named DID is proposed. It uses the hierarchical routing method. Non-Cluster Head nodes validate the Cluster Head nodes in a distributed way, which can reduce the dependency on the sink. The features of connectivity, intrusion tolerance and energy consumption in DID are also discussed intensively in this dissertation. DID is a good reference for the research of distributed node identification validation. Considering several QoS parameters, the dissertation presents a secure routing protocol REAR which is suitable for multimedia WSN. REAR can provide a kind of low-delay and energy-efficient data delivery service for multimedia sensor nodes. It adds pseudo-random codes into the multimedia messages so that data security can be guaranteed at the cost of few redundancy and computation. REAR is an explorer for the security routing method under multiple performance requirements and contributes to the future research on multimedia WSN with QoS. In the end of this dissertation, the related research methods for simulation and testing in WSN are analyzed. The design and implementation of a testing platform fitting for the routing protocol research is given. The self-developed sensor node uses ATmega128L as the micro-processor, CC2420 as the wireless transceiver, and TinyOS2.0 as the operation system. The testing platform solves the problem of result deviation that is derived from model simplification. It is an advanced testing environment for future research on routing protocols.The protocols and algorithms mentioned above are designed for routing security and energy-efficiency in WSN. The technologies of cryptography, routing discovery, pseudo-random codes are combined. The security mechanisms, such as identification authentication, information validation, intrusion detection, are all implemented. The solutions play an important role in the security framework of routing layer and must benefit the related research. Moreover, the performance of energy consumption, network connectivity and intrusion resistance are also tested by simulation experiments. The experiment results are analyzed and evaluated in this dissertation.