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التحسس المضغوط في الشبكات اللاسلكية

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 Publication date 2013
and research's language is العربية
 Created by Shamra Editor




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References used
S. Boyd and L. Vandenberghe, Convex Optimization. Cambridge University Press, 2004
D. Koller and N. Friedman, Probabilistic Graphical Models: Principles and Techniques. The MIT Press, 2009
Ryan W. Thomas, “Cognitive Networks”, Ph.D. dissertation, Virginia Polytechnic Institute, 2007
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Compressive Sensing (CS) shows high promise for fully distributed compression in wireless sensor networks (WSNs). In theory, CS allows the approximation of the readings from a sensor field with excellent accuracy, while collecting only a small fra ction of them at a data gathering point. However, the conditions under which CS performs well are not necessarily met in practice. CS requires a suitable transformation that makes the signal sparse in its domain. Also, the transformation of the data given by the routing protocol and network topology and the sparse representation of the signal have to be incoherent, which is not straightforward to achieve in real networks. In this paper we investigated the effectiveness of data recovery through joint Compressive Sensing (CS) and Principal Component Analysis (PCA) in actual WSN deployments. We proposed a novel system, called CS-PCA that embeds a feedback control mechanism to automatically change the compression ratio through changing the number of transmitting sensors, while bounding the reconstruction error. The considered recovery techniques in the proposed system are: biharmonic Spline (Spline), Deterministic Ordinary Least Square (DOLS), Probabilistic Ordinary Least Square (POLS) and Joint CS and PCA (CS-PCA). We found that the later outperform all other interpolation technique in the case of slow varying signals, while POLS was the most effective in case of fast varying signals that( low correlation less than 0.45)
Wireless Mesh Networks, WMNs, are foreseen to be an alternative to LANs and last- mile access infrastructures, and they have many unique characteristics, such as ease of deployment and installation, and cost efficiency. Security is crucial for WMNs to be widely accepted as internetworking and access network technologies. Access control, as a security requirement, is one of the most important pillars that lay down the foundation for such an acceptance. We identify in this paper the criteria that should be fulfilled by a viable security solution to control access to WMNs, and specify DUA, a security scheme, that allows for mutual authentication. DUA is based on the distribution of authentication key material over many nodes in such a way that any coalition of a predetermined threshold of corrupted nodes or fewer does not compromise the security of the system. Further, the key material is never handled by a single node. In addition, DUA provides for efficiency through the use of lightweight cryptographic operations.
Mobile wireless networks consist of a set of cooperative and mobile nodes, each node can move randomly at a specific speed in all directions without any control of a central manager. This type of networks has become a hot research topic due to its military application and suitability for emergencies and natural disasters. Due to the lack of fixed infrastructure, the routing process becomes the major problem in this type of networks, where the responsibility of routing is transferred to each node. Over the last few years, a number of traditional routing protocols has been proposed, but these protocols do not support quality of service in different environments. Some studies have improved some of these protocols to support quality of service for specific environments. This research identifies and analysis some of these improved protocols.
WLANs have evolved into the best choice in a number of situations such as government institutions and airports, but because of the open transport in these networks increased the possibility of security attacks, which required the use of security prot ocols to protect the network and to protect users. This research examines and evaluates the impact of security protocols on WLAN performance in order to select the optimal protocol, the impact of these protocols on network performance has been evaluated by adding those Protocols to open source GloMoSim environment, And recent simulation results show that the performance of these protocols are varies according to the environment applied within them, noting that there is no effective Protocol in all environments, i.e. the suitable Protocol in an environment may be unsuitable in other ones. After comparing performance results in simulations with performance results in the real network, we can see that the best performance protocol is WEP. Also, The best protocol for both performance and security is the WPA2. Hence, our choice to one of the security protocols depends on what we want to secure in the level of protection and the performance of the network.

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