This article assesses the performance of a virtual pheromone-based sectored dispersion algorithm which is implemented on a low-cost miniature mobile robotic platform using sonar sensing. The approach is a distributed ...
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This article assesses the performance of a virtual pheromone-based sectored dispersion algorithm which is implemented on a low-cost miniature mobile robotic platform using sonar sensing. The approach is a distributed one and the robotic platform and sensor array are sufficiently inexpensive that they can be employed in undergraduate research and/or for coursework in a small college environment
We address the problem of placing a sensor network so as to minimize the uncertainty in estimating the position of targets. The novelty of our formulation is in the sensing model: we focus on stereo sensors where the ...
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We address the problem of placing a sensor network so as to minimize the uncertainty in estimating the position of targets. The novelty of our formulation is in the sensing model: we focus on stereo sensors where the measurements from two sensors must be combined for an estimation. We study two versions of this problem. In the first version, which we call the placement problem, we are given a workspace and an error threshold. The objective is to place a minimum number of cameras so that no matter where the target is located in the workspace, the uncertainty in localizing it is less than the threshold. For this problem, we present an approximation algorithm and prove that the deviation of its performance from the optimal value is bounded by a constant. In the second version, called the deployment problem, we study the problem of relocating a mobile sensor team to minimize the uncertainty in localizing possibly moving targets. We present a distributed, discrete-time algorithm which explicit addresses communication and motion constraints and show how to compute the optimal move within the time-step for a given target/sensor-pair assignment. The utility of the algorithm is demonstrated with simulations
Large scale wireless ad-hoc networks of computers, sensors, PDAs etc. (i.e. nodes) are revolutionizing connectivity and leading to a paradigm shift from centralized systems to highly distributed and dynamic environmen...
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Large scale wireless ad-hoc networks of computers, sensors, PDAs etc. (i.e. nodes) are revolutionizing connectivity and leading to a paradigm shift from centralized systems to highly distributed and dynamic environments. A plethora of routing algorithms have been proposed for the network path discovery ranging from broadcasting/flooding-based approaches to those using Global Positioning systems (GPS). In this paper we propose a novel decentralized infrastructure that self-organizes wireless devices in an ad-hoc network, where each node has one or more virtual coordinates through which both message routing and data management occur without reliance on either flooding/broadcasting operations or GPS. The resulting ad-hoc network does not suffer from the dead-end problem, which happens in geographic-based routing when a node is unable to locate a neighbor closer to the destination than itself. The multi-dimensional data management capability will be described showing, as an example, how the location service reduces to a simple query, like for any other data type. Extensive performance analysis and experiments have been conducted and the results compared to GPSR, which is considered the most efficient routing solution not using broadcast operations. Our approach shows significant performance gains
We propose a distributed multiresolution representation of sensor network data so that large-scale summaries are readily available by querying a small fraction of sensor nodes, anywhere in the network, and small-scale...
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We propose a distributed multiresolution representation of sensor network data so that large-scale summaries are readily available by querying a small fraction of sensor nodes, anywhere in the network, and small-scale details are available by querying a larger number of sensors, locally in the region of interest. A global querier (such as a mobile collector or unmanned aerial vehicle) can obtain a lossy to lossless representation of the network data, according to the desired resolution. A local querier (such as a sensor node) can also obtain either large-scale trends or local details, by querying its immediate neighborhood. We want the encoding to be robust to arbitrary, even time-varying, wireless communication connectivity graphs. Thus we want to avoid cluster heads or deterministic hierarchies that are not robust to single points of failure. We propose a randomized encoding which enables both robustness, and distributed computation that does not require long distance coordination or awareness of network connectivity at individual sensors. Our distributed encoding algorithm operates on local neighborhoods of the communication graph
The need for efficient and secure localization is an important issue in a scalable self-organizing network. However, exiting secure solutions are not well suitable or effective for wireless sensor and actor networks (...
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The need for efficient and secure localization is an important issue in a scalable self-organizing network. However, exiting secure solutions are not well suitable or effective for wireless sensor and actor networks (WSANs) because of the features of WSANs (e.g. node heterogeneity). In this paper, we propose a novel approach (SeLoc) to secure localization for WSAN based on DV-Hop and hidden actors. After passively receiving authentication messages and minimum hop numbers from sensor nodes, these nearby actors distributively compute these sensors' location by actor-actor coordination and maximum likelihood estimators (MLE). By filtering inaccurate/false localization information, the SeLoc localization scheme can prevent these location attacks and improve the accuracy of localization. In addition, we also propose the voting-based location verification scheme in this paper. This verification scheme cannot only effectively decrease the success probability of attack, but also tolerate attacks to some extend. The analysis shows that SeLoc scheme is robust against location attacks and against other attacks like wormhole attacks, Sybile attacks. Also, comparing with other infrastructure-centric localization schemes, SeLoc scheme is energy saving, economical and secure for WSAN by fully using the features of WSAN
Wireless mesh networks (WMNs) are evolving to be the key technology of the future. As the WMNs are envisioned to provide high bandwidth broadband service to a large community of users, the Internet gateway (IGW) which...
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Wireless mesh networks (WMNs) are evolving to be the key technology of the future. As the WMNs are envisioned to provide high bandwidth broadband service to a large community of users, the Internet gateway (IGW) which acts as a central point of Internet attachment for the mesh routers, it is likely to be a potential bottleneck because of its limited wireless link capacity. We propose a novel technique that elegantly balances the load among the different IGWs in a WMN. We switch the point of attachment of an active source serviced gateway depending on the average queue length at the IGW. The proposed load balancing scheme includes: an initial gateway discovery module, which determines a primary gateway for a mesh router and a load balancing module that rebalances the load among the gateways. We use ns-2 for evaluating our proposed scheme and we observe that the proposed scheme is able to balance the traffic efficiently
We address the deployment issues in a hybrid sensor network consisting of both static and mobile sensor nodes. Existing deployment schemes often assume either known regular boundaries of the region, or that mobile sen...
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We address the deployment issues in a hybrid sensor network consisting of both static and mobile sensor nodes. Existing deployment schemes often assume either known regular boundaries of the region, or that mobile sensors are able to detect the region boundary. This is overly idealistic especially for unknown, outdoor environments. In our proposed two-phase deployment scheme, following their initial random deployment, the static sensors estimate the boundary of the unknown region by using the right-hand rule. This phase results in the identification of static boundary nodes, B-nodes. The mobile sensors are assumed concentrated at one or more points within the target area. In phase II, mobile sensor nodes spread in the target area in a distributed manner using one of the proposed variations of the virtual force algorithm. Neighboring B-nodes form a Virtual Boundary and exerts repulsive forces on mobile nodes to keep them in the target area. Using simulations, we demonstrate the effectiveness of our proposed scheme in uniformly deploying mobile sensor nodes in a hybrid sensor network
This paper presents a content-based decentralized information aggregation service for pervasive environments. The service provides a uniform query interface where aggregation queries are specified using content descri...
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This paper presents a content-based decentralized information aggregation service for pervasive environments. The service provides a uniform query interface where aggregation queries are specified using content descriptors in the form of keywords, partial keywords, wildcards and ranges. The service guarantees that all data that matches a complex/range query was located and aggregated in an efficient and scalable way. The design of the aggregation service uses a decentralized aggregation trie along with a distributed and decentralized query engine. The deployment and experimental evaluation of the aggregation service are also presented. Evaluations include simulations as well as experiments using deployments on local-area network at Rutgers and wide-area PlanetLab testbed
Wireless sensor and actor networks (WSANs) constitute an emerging and pervasive technology that is attracting increased interest for a wide range of applications. WSANs have two major requirements: coordination mechan...
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Wireless sensor and actor networks (WSANs) constitute an emerging and pervasive technology that is attracting increased interest for a wide range of applications. WSANs have two major requirements: coordination mechanisms for both sensor-actor and actor-actor interactions, and real-time communication to perform correct and timely actions. Additionally, the development of WSAN applications is notoriously difficult, due to the extreme resource limitations of nodes. This paper introduces a framework to facilitate the task of the application programmer taking into account these special characteristics of WSANs. We propose a real-time component model using light-weight components. In addition, a high-level coordination model based on tuple channels is integrated into the framework including high-level constructs that abstract the details of communication and facilitate the data-centric behavior of sensor queries.
In the last few years, there has been a dramatic growth of global, distributed applications such as Skype for VoIP telephony, P2P file sharing systems, and software/content distribution networks. Almost in parallel, a...
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In the last few years, there has been a dramatic growth of global, distributed applications such as Skype for VoIP telephony, P2P file sharing systems, and software/content distribution networks. Almost in parallel, a number of different monitoring overlay networks have been proposed to monitor the health of such systems for facilitating tasks like performance planning and problem solving. An important task of any monitoring overlay is the computation of aggregation functions such as MEAN over a set of nodes. However, in the face of multi-million nodes' networks, the computation of any aggregation function over the whole network or even a large subset of it is challenging. Every query scheme has to be robust against chum - nodes join and leave the system in arbitrary rates - and scalable up to millions of nodes. Consider the simple approach to aggregation. We may first do a broadcast to the network with an aggregate query and then have each node return its local value. Clearly, this would take significant time to complete in a large network. Moreover, without suitable coordination, the responses may collectively become a DDoS attack to the querying node. The lack of scalability in this approach has led to in-network computation, where an overlay is constructed to disseminate and compute the query in a distributed manner [1]. Several variations to computing aggregates have been proposed for sensor networks, Grids and cluster-based applications with each approach being focused on the constraints imposed by the network under study. Considine et al. [2] for example propose the use of duplicate insensitive sketches to compute SUM aggregates for networks with resource constraints and node failures such as sensor overlays. Other systems like Astrolabe [3] target smaller and less dynamic networks by constructing a fault resilient monitoring network to cope with network partitioning. In this paper, we address the problem of computing aggregate functions for large-scale netwo
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