الفهرس 
Chapter 1 Introduction
Optimal Number of Clusters.Only 14 pages are availabe for public view
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Abstract
The Research in Wireless Sensor Networks (WSNs) has made a significant progress recently, especially the area of key management, which plays a central role for protecting group communication in sensor networks. In sensor networks, the data are crucial and must keep secrecy in data communication. To achieve data confidentiality, adversary should not have access to the group communication. Therefore, due to the limited memory resources and energy constraints of sensor nodes, reducing the communication and storage overhead, and improving the resilience against the node capture attack become a must.
So, when we talk about security problems in the wireless sensor networks. In the beginning, we must talk about the limited energy problems facing these types of networks, which in turn represent limitations in the creation and application of wireless networks. Hence, different ways of saving energy and optimizing the available energy resources in these types of networks should be explored and exploited. This has been our motivation to propose two research papers that present new ways of saving energy as well as optimizing the use of energy resources. This, in turn, will be reflected in the creation and development of suitable security techniques for the WSNs.
In our first proposal about saving energy, we study the effect of heterogeneous nodes, With respect to their energy, in the hierarchically clustered wireless sensor networks. our new approach is studying and analyzing the effect of fixed clustering and event-driven on the network lifetime. Our results show that fixed-clustering OELP can improve system lifetime by an order of magnitude compared with previous related work research.
In this type of network, the information is essential and need to keep the mystery in information communication. To accomplish information confidentiality, enemy ought not to approach the communication between sensors in the group. To address these restrictions, we introduce an Improved group Key Management utilizing Symmetric Key for Cluster-based Wireless Sensor Networks. The presented scheme adopts the pair-wise key management generation, distributes the keys efficiently within a cluster and updates periodical keys. By this way, we provide continuous transmission security and avoids dangerous attacks from malicious nodes and mitigate the node compromise attack in WSNs communication.