Current Issue : July - September Volume : 2012 Issue Number : 3 Articles : 5 Articles
Wireless sensor networks (WSNs) can be used in a wide range of environments. Due to the inherent characteristics of wireless\r\ncommunications, WSNs are more vulnerable to be attacked than conventional networks. Authentication and data confidentiality\r\nare critical in these settings. It is necessary to design a useful key management scheme forWSNs. In this paper, we propose a novel\r\nkey management scheme called MAKM (modular arithmetic based key management). The proposed MAKM scheme is based on\r\nthe congruence property of modular arithmetic. Each member sensor node only needs to store a key seed. This key seed is used\r\nto compute a unique shared key with its cluster head and a group key shared with other nodes in the same cluster. Thus, MAKM\r\nminimizes the key storage space. Furthermore, sensor nodes in the network can update their key seeds very quickly. Performance\r\nevaluation and simulation results show that the proposed MAKM scheme outperforms other key-pool-based schemes in key\r\nstorage space and resilience against nodes capture. MAKM scheme can also reduce time delay and energy consumption of key\r\nestablishment in large-scaleWSNs....
This is an investigation of Wireless Sensor Networks (WSNs) using Memsic�s XMesh routing protocol on MICAz wireless motes.\r\nIt focuses on the study of the practical aspects of WSNs� power efficiency and network characteristics, which play a critical role\r\nin real-word WSN deployments for environmental monitoring. Based on an experimental study and following a quantitative\r\napproach, this work examines XMesh�s high power and low power operation modes and the data transmission intervals, among\r\nother factors. Route utilization was identified as a major contributor of the mote�s battery use. A field study was conducted as\r\na point of comparison and the results obtained were comparable to the laboratory tests with regards to the battery life and the\r\nmote�s route utilization. The network reliability was found to be considerably lower in the field study. In addition, it was found\r\nthat the originalWSN gateway, used during the study, presented severe practical limitations regarding the system�s robustness and\r\nreliability. To address these problems, we present a solution based on our integrated network and data management system, which\r\nsuccessfully facilitates the deployment of a newWSN gateway and significantly improves the operational robustness and reliability\r\nof theWSN system....
Wireless sensor networks include a wide range of potential applications to improve the quality of teaching and learning in a\r\nubiquitous environment. WSNs become an evolving technology that acts as the ultimate interface between the learners and the\r\ncontext, enhancing the interactivity and improving the acquisition or collection of learner�s contextual information in ubiquitous\r\nlearning. This paper presents a model of an effective and interactive ubiquitous learning environment system based on the concepts\r\nof ubiquitous computing technology that enables learning to take place anywhere at any time. The u-learning model is a webbased\r\ne-learning system utilizing various state-of-the-art features of WSN that could enable learners to acquire knowledge and\r\nskills through interaction between them and the ubiquitous learning environment. It is based on the theory of connectivism which\r\nasserts that knowledge and the learning of knowledge are distributive and are not located in any given place but rather consist of\r\nthe network of connections formed from experiences and interactions with a knowing community. The communication between\r\ndevices and the embedded computers in the environment allows learners to learn in an environment of their interest while they\r\nare moving, hence, attaching them to their learning environment....
Density control is of great relevance for wireless sensor networks monitoring hazardous applications where sensors are deployed\r\nwith high density. Due to the multihop relay communication and many-to-one traffic characters in wireless sensor networks, the\r\nnodes closer to the sink tend to die faster, causing a bottleneck for improving the network lifetime. In this paper, the theoretical\r\naspects of the network load and the node density are investigated systematically. And then, the accessibility condition to satisfy that\r\nall the working sensors exhaust their energy with the same ratio is proved. By introducing the concept of the equivalent sensing\r\nradius, a novel algorithm for density control to achieve balanced energy consumption per node is thus proposed. Different from\r\nother methods in the literature, a new pixel-based transmission mechanism is adopted, to reduce the duplication of the same\r\nmessages. Combined with the accessibility condition, nodes on different energy layers are activated with a nonuniform distribution,\r\nso as to balance the energy depletion and enhance the survival of the network effectively. Extensive simulation results are\r\npresented to demonstrate the effectiveness of our algorithm....
Detecting abnormal events represents an important family of applications for wireless sensor networks. To achieve high\r\nperformance of event detection, a sensor network should stay active most of the time, which is energy inefficient for battery\r\ndriven sensor networks. This paper studies the fundamental problem of bounding detection delays when the sensor network is\r\nlow duty cycled. We propose a novel approach for statistically bounding detection latency for event detection in sensor networks.\r\nThe key issue is the wakeup scheduling of sensor nodes and minimization of wakeup activity.We propose a lightweight distributed\r\nalgorithm for coordinating the wakeup scheduling of the sensor nodes. A distinctive feature of this algorithm is that it ensures that\r\nthe detection delay of any event occurring anywhere in the sensing field is statistically bounded. In addition, the algorithm exposes\r\na convenient interface for users to define the requirement on detection latency, thereby tuning the intrinsic tradeoff between\r\nenergy efficiency and event detection performance. Extensive simulations have been conducted and results demonstrate that this\r\nalgorithm can successfully meet delay bound and significantly reduce energy consumption....
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