For economic reasons sensor networks are often implemented with resource constrained micro-controllers and low-end radio transceivers. Consequently, communication is inherently unreliable and especially multi-hop comm...
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For economic reasons sensor networks are often implemented with resource constrained micro-controllers and low-end radio transceivers. Consequently, communication is inherently unreliable and especially multi-hop communication suffers severely from packet losses. Transmission protocols that rely on implicit acknowledges for multi-hop communication are energy efficient but require symmetric communication links to work properly. In this paper we introduce IMPACT, a family of transmission protocols that rely on implicit acknowledges and employ a cross layer approach to handle asymmetric links.
We consider the problem of self-deployment and relocation in mobile wireless networks, where nodes are both sensors and actuators. We propose a unified, distributed algorithm that has the following features. During de...
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We consider the problem of self-deployment and relocation in mobile wireless networks, where nodes are both sensors and actuators. We propose a unified, distributed algorithm that has the following features. During deployment, our algorithm yields a regular tessellation of the geographical area with a given node density, called monitoring configuration. Upon the occurrence of a physical phenomenon, network nodes relocate themselves so as to properly sample and control the event, while maintaining the network connectivity. Then, as soon as the event ends, all nodes return to the monitoring configuration. To achieve these goals, we use a virtual force-based strategy, which proves to be very effective even when compared to an optimal centralized solution.
A regeneration-based approach is undertaken to derive an expression for the expected value of total service time for an arbitrary customer distribution when scheduling is performed in a distributed queuing system. The...
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A regeneration-based approach is undertaken to derive an expression for the expected value of total service time for an arbitrary customer distribution when scheduling is performed in a distributed queuing system. The service times and the transfer delays for customers in the shared communication medium are both considered random. The theory is applied to a distributed wireless-sensor network and the interplay between the total service time and the energy consumption of each sensor is investigated.
In this paper, we compare the efficiency of fault detection and diagnosis in networks having different topological properties, such as scale-free networks and Erdos-Renyi random graphs. Efficiency measures include bot...
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In this paper, we compare the efficiency of fault detection and diagnosis in networks having different topological properties, such as scale-free networks and Erdos-Renyi random graphs. Efficiency measures include both the number of tests (e.g., end-to-end network probes) necessary for diagnosis and the computational complexity of diagnosis. We observe that diagnosis in scale-free networks typically requires significantly larger number of tests than diagnosis in random networks. However, the computational complexity of diagnosis appears to be much lower for scale-free networks since the corresponding Bayesian network models used for probabilistic diagnosis tend to have much lower induced width - a topological parameter controlling the complexity of inference in Bayesian networks. We believe that our observations provide important insights for design and deployment of cost-efficient diagnostic methods in computer networks and distributedsystems.
Evaluating position uncertainties is a fundamental problem of wireless sensor network localization. A constraint set, including both positive and negative constraints, is constructed to bound sensor position. By proje...
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Evaluating position uncertainties is a fundamental problem of wireless sensor network localization. A constraint set, including both positive and negative constraints, is constructed to bound sensor position. By projecting the feasible region of this constraint set onto a 2D plane, the feasible scope of sensor position is computed to evaluate node position uncertainty. The projection result, called feasible geographic region (FGR), is approximated by its inner and outer polygon. The polygon approximation will converge to the actual FGR if we incrementally add more polygon vertices. A distributed algorithm is proposed to compute FGR. Finally, we study the impact of node position uncertainty upon a typical network application, target event detection. The feasible scope of target event position is computed even though the sensor position is not certain.
Physical attributes such as temperature exhibit gradual change in value with space. Observations from the sensor nodes are thus highly correlated. In this paper, we propose a scheme to exploit the spatial correlation ...
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Physical attributes such as temperature exhibit gradual change in value with space. Observations from the sensor nodes are thus highly correlated. In this paper, we propose a scheme to exploit the spatial correlation of data in a three dimensional wireless sensor network (WSN), in a way so as to reduce the number of transmissions in the network, thereby saving energy. The presented work is an extension of the earlier proposed TREG scheme which is only applicable to two dimensional WSN. Our scheme involves formation of binary tree and transmission of data along the tree nodes. Simulation has been carried out for different tree heights. Simulation results show that a tree height of four provides results with optimal values.
Bandwidth and energy reservation is a major challenge in a large scale wireless ad-hoc sensor network, such as ieee802.15.4-based LR-WPAN. To prolong lifetime of the whole network, improve network throughput, and supp...
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Bandwidth and energy reservation is a major challenge in a large scale wireless ad-hoc sensor network, such as ieee802.15.4-based LR-WPAN. To prolong lifetime of the whole network, improve network throughput, and support a simple topology management method in a large scale sensor network, a hierarchical clustering algorithm is proposed in this paper. This algorithm can be used for a network consisting of various capability devices, such as ieee802.15.4-based LR- WPAN. Through computing and comparing the potential of serving as a cluster-head device (PSCD) in distributed manner, devices with more capability are chosen for cluster heads and PNC (Piconet coordinator). Comparing with other methods, such as LEACH (low energy adaptive clustering hierarchy) (Hernzelman et al., 2000) and direct communication, simulation results show this method saves energy with significantly high throughput.
We consider the problem of localizing random sensor networks by means of time of arrival capabilities. Interactions among sensors are modeled by a mass-spring system. Masses (sensors) initially have a random estimatio...
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We consider the problem of localizing random sensor networks by means of time of arrival capabilities. Interactions among sensors are modeled by a mass-spring system. Masses (sensors) initially have a random estimation of their position. The knowledge of their distance from other masses is translated into connect masses with springs whose length should reach the estimated distances. This determines a set of forces to which masses are subject to. Starting from this configuration we propose several strategies reducing the overall time needed to reach the desired level of equilibrium.
Autonomous robotic wheelchairs are widely discussed in recent years. Most of autonomous robotic wheelchairs were developed based on rich computation architecture to deal with complicated navigation efforts such as per...
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Autonomous robotic wheelchairs are widely discussed in recent years. Most of autonomous robotic wheelchairs were developed based on rich computation architecture to deal with complicated navigation efforts such as personal computers or embedded computers. However, such rich computation architectures increase cost of robotic wheelchair when compared to conventional powered wheelchairs. At the same time, large amounts of energy consumptions, lower reliability, and inefficient size of personal computers reduce the practicability of robotic wheelchair. In this paper, we present a low cost solution to solve complicated wheelchair navigation problem based on distributedcomputing architecture. This solution is developed based on the programmable System-on-Chip (PSoC) computing and control architecture. The tasks within autonomous navigations are categorized into human machine interface, sensor collection, fuzzy logic based navigation functions, closed loop motion controller, and these tasks are individually implemented using the PSoC. Finally, the task oriented PSoC are integrated and fused to perform autonomous navigations of robotic wheelchairs. Consequently, the proposed PSoC based distributedcomputing architecture was successfully implemented and experimentally tested. The navigation results were verified using the results inferred from the personal computer based computing architecture.
In a wireless mesh network (WMN), mesh routers (MRs) are interconnected by wireless links and form a wireless backbone to provide ubiquitous high-speed Internet connectivity for mobile clients. The wireless backbone i...
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In a wireless mesh network (WMN), mesh routers (MRs) are interconnected by wireless links and form a wireless backbone to provide ubiquitous high-speed Internet connectivity for mobile clients. The wireless backbone is tightly integrated with the Internet by nodes called as Internet gateways (IGWs). In this paper, we address the IGW deployment problem which is shown to be NP-hard. We first formulate it as a linear program (LP) issue, then develop two heuristic algorithms for the purpose of cost-efficient IGW deployment. We further compare our algorithms with a leading approach by extensive simulations. Our analysis shows the effectiveness of the proposed algorithms.
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