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End-to-end reliability of communications is an important requirement in many applications of wireless sensor networks. For this reason, a number of reliable transport protocols specifically designed for wireless sensor networks have been proposed in the literature. Besides providing end-to-end reliability, some of those protocols also address the problems of fairness and congestion control, and they...
Recently, researchers and engineers began considering the use of WSN in time-sensitive applications. For effective real-time communications, it is important to solve the problem of contention to the communication medium providing an efficient bandwidth allocation mechanism. In this paper we tackle with the problem of performing timely detection of events by a WSN. We propose a real-time bandwidth...
This paper makes the claim that in an ad-hoc wireless sensor network, the node localization obtained using semi-definite programming methods is significantly improved by removing from the problem formulation those nodes that do not have a path to any anchor node. An algorithm is presented to identify and remove these components. Experiments conducted in this study strongly support our claim.
Sensor networks are networks of sensing units that acquire data from the environment and transmit them towards a base station. Depending on the specific nature of the application and its constraints, the communication among units and from units to the base station may rely on wired, wireless or a hybrid technology. In those scenarios where units communicate through a wired technology, e.g., a fieldbus,...
ALYZE is a tool for planning and analyzing wireless sensor networks (WSN). The main feature is a new intuitive visualization and handling concept that eases the task to analyze a wireless sensor network. The system localizes sensor nodes that have been attached to a magnetic whiteboard. A video projector shows a real time visualization of the network topology, routing tables, node state, sensor data,...
Wireless sensor networks are expected to operate in an unattended manner for long periods of time. As a result, they should be able to tolerate faults and maintain a reasonable performance level. Therefore, we propose two fault-tolerant clustered De Bruijn based multi layered architectures, a fault-tolerant routing scheme and a distributed fault diagnosis algorithm. The performance of the proposed...
This paper presents a Secure Code Update (SCU) system for Wireless Sensor Networks (WSNs). This solution achieves different security goals. First, through a dedicated authentication protocol it provides protection against the corruption of code images during their dissemination. Authentication routines exploit a lightweight asymmetric T-time signature algorithm and allow the out-of-order reception...
Mobility of users carrying mobile devices with access to wireless networks creates the need to provide uniform and immediate access to information. In this scenario, a new educational model, called Ubiquitous Learning, has been studied. In this model, the educational processes are related to the learner's situation, i.e. they are context-aware. This allows the access to educational resources be adapted...
We describe a class of metrics which relate the accuracy of a sensor network measurement one achieves when using a certain MAC protocol with the energy the MAC protocol consumes. To measure accuracy we compare the true values of the physical phenomena and the values reconstructed at the sink. We propose three ways to compare them, the difference between the function of the physical phenomena and the...
Data loss in wireless communications greatly affects the reconstruction quality of wirelessly transmitted images. Conventionally, channel coding is performed at the encoder to enhance recovery of the image by adding known redundancy. While channel coding is effective, it can be very computationally expensive. For this reason, a new mechanism of handling data losses in wireless multimedia sensor networks...
We consider a wireless sensor and actor network (WSAN) consisting of a large number of tiny, low-cost sensors uniformly and independently distributed in a two-dimensional geographical region around a few powerful entities, called actors. To save energy, the sensors operate according to sleep/awake schedules in an asynchronous manner. In this setting, we propose a semi-distributed, actor-centric localization...
One of the most challenging research tasks in the field of wireless sensor networks is controlling the power consumption of batteries and prolonging network lifetime. For sensor networks which consist of a large number of sensor nodes, self-organized control is more suitable than centralized control. In particular, research on bio-inspired self-organization methods attracts attention due to the potential...
Middleware for wireless sensor networks and middleware for context-aware applications both provide information abstraction and programming support for gathering, pre-processing, and managing sensor data. However the former mostly concentrates on optimising the operations of the resource constrained hardware and simplifying access to the raw sensor data while the latter focuses on gathering sensor...
Reverse Auction is one of the best-known market-based mechanisms for allocation of delay-constrained tasks to distributed sensor nodes in wireless sensor network as a typical application in pervasive computing. However, costly message exchanges with enormous overheads among resource-constrained sensor nodes for decision making are required. In this paper, a novel energy/delay-efficient distributed...
In this paper, we propose a Hierarchical Role-based Data Dissemination approach, named HRDD, for large-scale wireless sensor networks with multiple mobile sinks. In HRDD, we use a hierarchical cluster-based structure to discover and maintain the routing paths for distributing data to the mobile sink. We assign two roles, named Indexing Agent and Gateway Agent, to some sensor nodes in the wireless...
We are witnessing a tremendous hype on the Internet of Things paradigm, with not only research projects, but also commercial products claiming to implement its fundamental mechanisms. Smart-connected-objects designers often have to face decisions on the global architecture of the service, since no single solution is valid for all the cases. In this paper, we explore the different criteria for designing...
A platform-independent communication mechanism is essential for the seamless integration of embedded devices into the Web of Things. Web services provide for such communication, though there remains an open question as to whether they are suitable for hardware-constrained devices. While there is a general perception that they are too resource-intensive, there are few scientific studies dedicated to...
By harnessing sensors embedded in personal end devices, Participatory Sensing enables novel applications, but also raises severe privacy concerns. Instead of using existing centralized privacy mechanisms that remain obscure to the participants, we propose to involve the participants themselves into the process to protect privacy by interacting directly with others users using their available sensors...
This work introduces an intuitive XML-based Event Specification Language (ESL) that simplifies event configuration to a level that is even suitable for non-professionals. It features hardware independent description elements to define complex phenomena and improves these by tailor-made voting schemes and application constraints. Based on that, a novel fully decentralised mechanism to autonomously...
Tiny, wireless, sensors embedded in a large number of Internet-capable devices-smart phones, cameras, cars, toys, medical instruments, home appliances and energy meters-can generate an enormous volume of small bits of data such as temperature and humidity readings, GPS co-ordinates and energy usage. The real value of this data lies in its analysis, which can lead to significant insights and actions...
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