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ABSTRACT: Ubiquitous systems are generally embedded into the environment and provide their services all the time and everywhere. In order to increase transparency and personalization, ubiquitous applications are normally context-aware, i.e., they use information about entities of interest to adapt their services. Since they are connected to everyday elements, such systems are frequently shared by two or more users, who may provide conflicting contextual data. Therefore, these systems can reach an inconsistent state, in which they are unable to decide how to perform their intended adaptations. This work proposes a novel methodology that can detect and solve conflicts of interest for ubiquitous context-aware applications with different characteristics. Besides, the developed approach considers the trade-off between quality of services and resources consumption in order to select and apply a conflict resolution algorithm. Results obtained through simulations showed that the proposed solution can provide reasonable users' satisfaction levels, as well as to save system resources.
Local Computer Networks (LCN), 2010 IEEE 35th Conference on; 11/2010
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ABSTRACT: The context-aware computing is a research field that defines systems capable of adapting their behavior according to any relevant information about entities (e.g., people, places and objects) of interest. Ubiquitous systems are closely related to the use of contexts and are frequently shared among multiple users, once they are designed to be embedded into everyday environments such as houses, cars, and offices. In scenarios where more than one user shares the same ubiquitous context-aware application, conflicts may occur during adaptation actions due to individual profile divergences and/or environment resource incompatibility. In such situations it is interesting to use some mechanism to detect and solve those conflicts, considering what is better for the group but also being fair enough with each individual demand, whenever possible. This work presents the important concepts in the collective ubiquitous context-aware applications field through a disaster emergency attendance application. Furthermore, the proposal of a methodology for conflict detection and resolution is described. The obtained simulation results showed how this methodology can maintain the application working properly while solving the collective conflicts, managing resource consumption and providing an interesting user satisfaction average.
Computers and Communications, 2009. ISCC 2009. IEEE Symposium on; 08/2009
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ABSTRACT: The context-aware computing is a research field that defines systems capable of adapting their behavior according to any relevant information about entities (e.g.,people, places and objects) of interest. The ubiquitous computing is closely related to the use of contexts, since it aims to provide personalized, transparent and on-demand services. Ubiquitous systems are frequently shared among multiple users, once they are designed to be embedded into everyday objects and environments such as houses, cars and offices. In scenarios where more than one user shares the same ubiquitous context-aware application, conflicts may occur during adaptation actions due to individual profiles divergences and/or environment resources incompatibility. In such situations it is interesting to use computer supported collaborative work techniques in order to detect and solve those conflicts, considering what is better for the group but also being fair enough with each individual demand, whenever possible. This work presents the important concepts on the collective ubiquitous context-aware applications field. Furthermore, it proposes a new methodology for conflicts detection and resolution that considers the trade-off between quality of services and resources consumption.
Computer Supported Cooperative Work in Design, 2009. CSCWD 2009. 13th International Conference on; 05/2009
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Advances in Wireless Ad Hoc and Sensor Networks. 01/2008;
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ABSTRACT: There are many approaches that can be applied to the management of wireless sensor networks (WSN) and nowadays the research in this field is only beginning. A management approach determines how the management monitor and control functions are performed by the network and network elements. Since a wireless sensor network presents severe resource constraints, a certain management approach must be chosen properly in order to optimize resource usage and at the same time satisfy the application requirements. In this paper we try to answer the following question: what is the tradeoff between to migrate management services or to adopt traditional approaches for WSN management? We have concluded from simulated and experimental results that the choice of the best approach to be adopted must consider the size of the network, the configuration of the nodes, the application goals and the management complexity, in terms of managed objects. We have also noticed that, despite the service migration approach being theoretically interesting for WSN management, for the sensor networks and sensor nodes hardware current technological situation, the approach would be applied with some negative impact on the performance of the network.
Computers and Communications, 2007. ISCC 2007. 12th IEEE Symposium on; 08/2007
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ABSTRACT: A fundamental goal of a wireless sensor network (WSN) is to collect and deliver data to external applications. Due to the strong constraints of these networks, routing algorithms usually consider application-specific characteristics and, consequently, there is no self-contained algorithm appropriate for every case. In particular, many WSN applications are event- driven. In such scenarios, the behavior of the network may vary a lot, which favors different algorithms at different instants. In these cases, hybrid adaptive solutions are more suitable by allowing the adoption of a better routing strategy in response to the variation of the network conditions. In this work, we evolve this approach by considering the temporal characteristic of event occurrence and detection through an estimation model. The proposed solution, called multi, predicts the need of routing infrastructure creation and maintenance for the adaptation between a reactive and a proactive strategy. To show the advantages of the proposed approach, an instance of multi is evaluated through simulations. Comparisons with its independent reactive and proactive components and other proposed solutions show improvements on energy consumption.
Communications, 2007. ICC '07. IEEE International Conference on; 07/2007
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ABSTRACT: Autonomic networks are able to monitor and control themselves without direct human intervention. The smallest unit of an autonomic network is the autonomic element (AE). This work presents the model and evaluation of a specific wireless sensor network (WSNs) AE, called autonomic sensor element (ASE). The ASE has been proposed considering WSNs hardware, software, communication and energy restrictions.
Autonomic Computing, 2007. ICAC '07. Fourth International Conference on; 07/2007
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ABSTRACT: Wireless sensor networks (WSNs) are characterized by having scarce resources. The usual way of designing network functions is to consider them isolatedly, a strategy which may not guarantee the correct and efficient operation of WSNs. For this reason, in this paper we propose an integrated design of network functions. We take two important WSN functions - density control and routing - as an example and present two approaches to integrate them. In particular, we present two solutions, named RDC-sync and RDC-integrated, which integrate a geographical density control algorithm with tree routing. The simulations experiments performed prove that the integrated design improves the network performance, especially when density control and routing are fully integrated.
Parallel and Distributed Processing Symposium, 2006. IPDPS 2006. 20th International; 05/2006
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ABSTRACT: The goal of a wireless sensor network (WSN) management solution is to promote network resources productivity and quality of services. This paper presents a comparative study of client/server (CS) and mobile agent (MA) approaches used in distributed self-management solutions for a hierarchical heterogeneous WSN, in which the managers are embedded into the cluster head nodes. These approaches were simulated and evaluated according to energy consumption. Considering energy consumption with transmission, the results reveal that the MA approach is more scalable than the CS one, tending to be more useful when the number of network elements and managed objects increases. On the other hand, the CS approach presents more interesting results regarding energy consumption with processing. Besides, the simulations performed also show that the MA size is an important parameter that impacts directly on the results
Network Operations and Management Symposium, 2006. NOMS 2006. 10th IEEE/IFIP; 05/2006
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ABSTRACT: In this paper we propose a new reconfigurable architecture for sensor nodes, called RANS-300, which can operate in applications demanding low power to high performance, although sacrificing the lifetime of the sensor node. This node has a FPGA board, which can be dynamically reconfigured to add new configuration, and has a Compact Flash device to expand the node possibilities
Emerging Technologies and Factory Automation, 2005. ETFA 2005. 10th IEEE Conference on; 10/2005
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IEEE Communications Magazine 09/2005; · 3.79 Impact Factor
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Integrated Network Management, 2005. IM 2005. 2005 9th IFIP/IEEE International Symposium on; 06/2005
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ABSTRACT: A wireless sensor network is a special kind of ad hoc network where the nodes can sense, actuate, compute and communicate with each other using point-to-point multi-hop communication. Sensor networks can be used in a wide range of applications, such as environmental monitoring and industrial applications. Despite their potential applications, such networks have particular features imposed by resource restrictions, such as low computational power, reduced bandwidth and specially limited power source. Nowadays, real wireless sensor networks infrastructures are still very expensive. Therefore, most of the evaluations of new protocols are being made through simulation tools. The objective of this work is to verify the applicability of using cellular automata to simulate some aspects of sensor networks. A simulator has been developed to evaluate an algorithm for a very common problem in sensor networks: the topology control. The solution presented is based on the geographical position and the operational states of the sensor nodes. The obtained results indicate that cellular automata can be used with success to simulate large wireless sensor networks.
Simulation Symposium, 2005. Proceedings. 38th Annual; 05/2005
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ABSTRACT: A wireless sensor network aims to collect data and, sometimes, control an environment. This kind of network is composed of hundreds to thousands of devices that have the capability of sensing, processing and wireless communicating, called sensor nodes. The sensor nodes are projected with small dimensions (cm<sup>3</sup> or mm<sup>3</sup>) and this size limitation ends up restraining the node resources, like energy, processor and transceiver capacity. The task of building and deploying management systems in environments where there will be tens of thousand of network elements with particular features and organization is very complex. This task becomes worse due to the physical restrictions of these unattended sensor nodes. In this paper we have implemented and evaluated some automatic services of configuration and performance management, proposed by a WSN management architecture called MANNA. This architecture is based on the paradigm of self-management, which contains the automatic functions and services of management using a minimum of human interference. This work aims to evaluate different WSN configurations considering an application of continuous data sensing and dissemination, and the effects of the management solution proposed for this network. The built application does temperature and carbon monoxide concentration level monitoring, in an urban area. The results show the cost-benefit relations of the different organizations and demonstrates that management can promote the productivity of the resources and control the quality of the provided services.
Network Operations and Management Symposium, 2004. NOMS 2004. IEEE/IFIP; 05/2004
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ABSTRACT: A wireless sensor network is a special kind of ad-hoc network with distributed sensing and processing capability that can be used in a wide range of applications, such as environmental monitoring, industrial applications and precision agriculture. Despite their potential applications, such networks have particular features imposed by resource restrictions, such as low computational power, reduced bandwidth and specially limited power source. In case of a network with a high density of sensor nodes, some problems may arise such as the intersection of sensing area, redundant data, communication interference, and energy waste. A management application is necessary to make the most of network resources. On the other hand, a high-density network can introduce a fault-tolerant mechanism, increase precision, and provide multi-resolution data. The network density control depends on the application. In this paper, we propose a method to set up which nodes should be turned off or on. The management may take the sensor node out of service temporally. Our design uses a Voronoi diagram, which decomposes the space into regions around each node. That schema could be used in management architecture for a wireless sensor network.
Local Computer Networks, 2003. LCN '03. Proceedings. 28th Annual IEEE International Conference on; 11/2003
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ABSTRACT: Wireless Sensor Networks (WSNs) have particular characteristics that do not allow to apply traditional distributed algorithms directly to them. In this work we adapt the algorithms Distributed Snapshot, Broadcast and Propagation of Information with Feedback (PIF) to WSNs and apply them to generate the Energy Map of a WSN. This map shows the behavior of such a network and can be used to predict its behavior. We simulate the algorithms proposed and show their number of messages, energy spent and execution time.
Distributed Computing Systems, 2003. FTDCS 2003. Proceedings. The Ninth IEEE Workshop on Future Trends of; 06/2003
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ABSTRACT: Wireless sensor networks (WSNs) are becoming an increasingly important technology that will be used in a variety of applications such as environmental monitoring, infrastructure management, public safety, medical, home and office security, transportation, and military. WSNs will also play a key role in pervasive computing where computing devices and people are connected to the Internet. Until now, WSNs and their applications have been developed without considering a management solution. This is a critical problem since networks comprising tens of thousands of nodes are expected to be used in some of the applications above. This article proposes the MANNA management architecture for WSNs. In particular, it presents the functional, information, and physical management architectures that take into account specific characteristics of this type of network. Some of them are restrict physical resources such as energy and computing power, frequent reconfiguration and adaptation, and faults caused by nodes unavailable. The MANNA architecture considers three management dimensions: functional areas, management levels, and WSN functionalities. These dimensions are specified to the management of a WSN and are the basis for a list of management functions. The article also proposes WSN models to guide the management activities and the use of correlation in the WSN management. This is a first step into a largely unexplored research area.
IEEE Communications Magazine 03/2003; · 3.79 Impact Factor
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Anais do 5o. Workshop de Comunicaç ao sem Fio (WCSF). 01/2003;
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ABSTRACT: The unplanned and random deployment of a Wireless Sensor Network (WSN) may impose a high node density on a specific region. This concentration can be exploited by density control mechanisms to increase network lifetime, by deactivating temporarily redundant sensor nodes. Previous approaches for density control in WSN focus in guaranteeing full sensing coverage of monitoring area. This work presents a new data-centric approach where density control is performed to increase network lifetime preserving precision of sampled data. Using statistical techniques, density is determined according to sampling. The results show that this approach achieved an improvement of 3 times of network lifetime, while it guarantees a data precision defined by a user.
Wireless and Mobile Communications, 2008. ICWMC '08. The Fourth International Conference on;
