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In intermittently connected sensor networks, wherein sensor nodes do not always have connected paths to the base station, preserving generated data inside the network is a new and challenging problem. We propose to preserve the data items by distributing them from storage-depleted data generating nodes to sensor nodes with available storage space and high battery energy, under the constraints that...
In a long-haul sensor network, sensors are remotely deployed over a large geographical area to perform certain tasks. We consider a class of such networks where sensors take measurements of one or more dynamic targets and send state estimates of the target(s) to a fusion center via satellite links. The severe loss and delay inherent over the satellite channels render insufficient the number of estimates...
Wireless mesh networks (WMNs) provide high-bandwidth wireless network access to mobile clients in extensible, robust multi-hop networks. WMNs support distributed service provision and data storage, catering to the advanced capabilities of current mobile devices. Services and data discovery using undirected broadcast or multicast messages, as in traditional discovery protocols, significantly harms...
Capacity studies for wireless networks typically focus on scheduling of transmissions but rarely on scheduling of radio sleep-wakeup. We show that in a multi-hop network setting the duty-cycling of radios results in a per-node throughput capacity of Θ(W ψ√log n/√n) as opposed to Θ(W ψ/√ n log n) where ψ is the fraction of time each node radio is active. Likewise, in a single-hop clique network the...
Extensive efforts have been made to study the asymptotic capacity, delay, and their tradeoffs for large-scale mobile ad hoc networks, under different mobility models and communication models. Majority results adopt the fixed-rate communication model, such as the protocol model and physical model, and none of them breaks the limitation of tradeoffs: delay/capacity = ω(1) so far, even for the simplest...
Extensive research has been performed on improving TCP performance in multi-hop wireless networks, but there have been relatively few experimental evaluations of this work. To make it easier to conduct research in this area, we are releasing WiFu, an open-source toolkit for developing experimental wireless transport protocols. WiFu provides for user-space development of reliable transport and rate...
In most delay tolerant network (DTN) applications, mobile nodes utilize WiFi radios to obtain local information and transmit data. One bottleneck on DTN delivery performance is the short communication range of the WiFi radio. Rather than designing efficient protocols on WiFi based DTN, we propose a novel dual-radio architecture by adding a long-range low-bitrate eagle eye (EE) radio on every node...
Wireless Sensor Network (WSN) deployment experiences show that data collected is prone to be imprecise and faulty due to internal and external influences, such as battery drain, environmental interference, sensor aging. An early detection of such faults is necessary for the effective operation of the sensor network. We focus on identifying data fault types and their causes. In particular, we propose...
Energy harvesting is one of the most promising technologies towards the goal of perpetual operation of wireless sensor networks (WSNs). Environmentally-powered systems, however, have to deal with the variable behavior of ambient energy sources, which results in different amounts and rates of energy available over time. To alleviate the problem of the harvested power being neither constant nor continuous,...
The SINR model has attracted much attention in the field of wireless networks. The path loss exponent α in the model is generally treated as a constant between two and six. However, in real scenarios, the path loss is influenced by many factors such as environment (vegetation and barriers), propagation medium (dry or moist air), the distance between the transmitter and the receiver, etc. Therefore,...
This paper introduces a modeling framework to analyze spatial node density in mobile networks under “waypoint”-like mobility regimes. The proposed framework is based on a set of first order ordinary differential equations (ODEs) that take as parameters (1) the probability of going from one subregion of the mobility domain to another and (2) the rate at which a node decides to leave a given subregion...
Nodes that are part of a multihop wireless network, typically deployed in mission critical settings, are expected to perform specific functions. Establishing a notion of reliability of the nodes with respect to each function (referred to as functional reliability or FR) is essential for efficient operations and management of the network. This is typically assessed based on evidence collected by nodes...
WSN applications are prone to bugs and failures due to their typical characteristics, such as being extensively distributed, heavily concurrent, and resource restricted. In this paper, we propose and develop a flexible and iterative WSN debugging system based on sequence mining techniques. At first, we develop a data structure called the vectorized Probabilistic Suffix Tree (vPST), an elastic model...
In this paper, we propose a generic approach to tracking multiple indistinguishable moving targets with wireless sensor networks. The tracking algorithm first separates the aggregate signals from multiple indistinguishable targets via the Blind Source Separation (BSS) method. Through the analysis on both the temporal and the spatial correlation of the separated individual signals, the tracking algorithm...
There are many ways to determine the boundary of an event based on Satellite imaging which does not provide accurate information. In many situations, there may not be enough time to monitor the effect of emergency and the affected area. Moreover, the event region could continuously change in the geographical region and a robust deployment of sensors is desirable that could capture maximum information...
This paper studies mobile barrier coverage (MBC) surrounding dynamic objects. In the real world, several dynamic objects can benefit from MBC. For example, marching troop can detect any adversary intrusion without blind spot by MBC. However, conventional works only focused on barrier coverage for static objects, which fail when the objects start to move. Issues to address these dynamic-object scenarios,...
Reliable sensor node localization is a critical and difficult task in a large number of wireless sensor networks applications. Received signal strength indication (RSSI) measurements are a simple and inexpensive way to localize mobile robots, but they suffer from large errors due to noise, occlusions, and multi-path specially in indoor environments. Kalman filters and their variations are widely adopted...
Monitoring in large scale environments is a typical mission in cooperative robotics. This task requires the exploration of a huge domain by a generally small number of sensor equipped mobile robots. As time restrictions prohibit an exhaustive global search, a sampling strategy is required that allows an efficient spatial mapping of the environment. This paper proposes an adaptive sampling strategy...
The synchronization problem of a network of interconnected systems has been deeply analyzed by the scientific community. In the case of identical systems, under suitable hypotheses, the synchronization depends on the network topology, and specifically on the ratio between the second smallest eigenvalue (algebraic connectivity) and spectral radius of the Laplacian matrix corresponding to the network...
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