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129
Node Placement for Connected Coverage in Sensor Networks
, 2003
"... We address the problem of optimal node placement for ensuring connected coverage in sensor networks. We consider two different practical scenarios. In the first scenario, a certain region (or a set of regions) are to be provided connected coverage, while in the second case, a given set of n points a ..."
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Cited by 68 (1 self)
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We address the problem of optimal node placement for ensuring connected coverage in sensor networks. We consider two different practical scenarios. In the first scenario, a certain region (or a set of regions) are to be provided connected coverage, while in the second case, a given set of n points are to be covered and connected. For the first case, we provide solutions that are within a small factor of the optimum. For the second case, we present an algorithm that runs in polynomial time, and guarantees a constant factor approximation ratio.
Initializing Newly Deployed Ad Hoc and Sensor Networks
 in Proceedings of 10 th Annual International Conference on Mobile Computing and Networking (MOBICOM
, 2004
"... A newly deployed multihop radio network is unstructured and lacks a reliable and e#cient communication scheme. In this paper, we take a step towards analyzing the problems existing during the initialization phase of ad hoc and sensor networks. Particularly, we model the network as a multihop quasi ..."
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Cited by 67 (15 self)
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A newly deployed multihop radio network is unstructured and lacks a reliable and e#cient communication scheme. In this paper, we take a step towards analyzing the problems existing during the initialization phase of ad hoc and sensor networks. Particularly, we model the network as a multihop quasi unit disk graph and allow nodes to wake up asynchronously at any time. Further, nodes do not feature a reliable collision detection mechanism, and they have only limited knowledge about the network topology. We show that even for this restricted model, a good clustering can be computed e#ciently. Our algorithm e#ciently computes an asymptotically optimal clustering. Based on this algorithm, we describe a protocol for quickly establishing synchronized sleep and listen schedule between nodes within a cluster. Additionally, we provide simulation results in a variety of settings.
Lattices for distributed source coding: Jointly Gaussian sources and reconstruction of a linear function
 IEEE TRANSACTIONS ON INFORMATION THEORY, SUBMITTED
, 2007
"... Consider a pair of correlated Gaussian sources (X1, X2). Two separate encoders observe the two components and communicate compressed versions of their observations to a common decoder. The decoder is interested in reconstructing a linear combination of X1 and X2 to within a meansquare distortion of ..."
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Cited by 45 (2 self)
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Consider a pair of correlated Gaussian sources (X1, X2). Two separate encoders observe the two components and communicate compressed versions of their observations to a common decoder. The decoder is interested in reconstructing a linear combination of X1 and X2 to within a meansquare distortion of D. We obtain an inner bound to the optimal ratedistortion region for this problem. A portion of this inner bound is achieved by a scheme that reconstructs the linear function directly rather than reconstructing the individual components X1 and X2 first. This results in a better rate region for certain parameter values. Our coding scheme relies on lattice coding techniques in contrast to more prevalent random coding arguments used to demonstrate achievable rate regions in information theory. We then consider the case of linear reconstruction of K sources and provide an inner bound to the optimal ratedistortion region. Some parts of the inner bound are achieved using the following coding structure: lattice vector quantization followed by “correlated” latticestructured binning.
Lowcoordination topologies for redundancy in sensor networks
 In ACM MobiHoc
, 2005
"... Tiny, lowcost sensor devices are expected to be failureprone and hence in many realistic deployment scenarios for sensor networks these nodes are deployed in higher than necessary densities to meet operational goals. In this paper we address the question of how nodes should be managed in such dens ..."
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Cited by 43 (0 self)
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Tiny, lowcost sensor devices are expected to be failureprone and hence in many realistic deployment scenarios for sensor networks these nodes are deployed in higher than necessary densities to meet operational goals. In this paper we address the question of how nodes should be managed in such dense sensor deployments so that the network topology formed by the active sensors is able to provide connectedcoverage to the entire area of interest and at the same time increase the lifetime of the network. In particular, we propose and study distributed, lowcoordination node wakeup schemes to efficiently construct multiple independent (nodedisjoint) sensor network topologies to achieve good fault tolerance. We propose and evaluate different distributed, random and patternbased wakeup policies for sensor nodes to construct connectedcovered topologies. Through analysis and simulations we demonstrate that in dense sensor deployment scenarios, these policies can construct nearoptimal topologies (within 2.7 % of the optimal) with zero coordination between nodes, as long as location information is available at the individual sensor nodes. Based on these observations, we develop and evaluate a few simple distributed, wakeup based topology construction algorithms that can realize similar performance bounds in realistic sensor deployments, with varying node densities. These algorithms differ in terms of the required level of coordination and the use of sensor location information, and generate connectedcovered topologies efficiently, with very low messageexchange overhead.
Complete Optimal Deployment Patterns for FullCoverage and k−Connectiviy (k ≤ 6) Wireless Sensor Networks
 In Proc. of ACM MobiHoc
, 2008
"... Abstract—In this paper, we study deployment patterns to achieve full coverage and kconnectivity (k ≤ 6) under different ratios of the sensor communication range (denoted by Rc) to the sensing range (denoted by Rs) for homogeneous wireless sensor networks (WSNs). In particular, we propose new patter ..."
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Cited by 34 (7 self)
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Abstract—In this paper, we study deployment patterns to achieve full coverage and kconnectivity (k ≤ 6) under different ratios of the sensor communication range (denoted by Rc) to the sensing range (denoted by Rs) for homogeneous wireless sensor networks (WSNs). In particular, we propose new patterns for 3 and 5connectivity. We also discover that there exists a hexagonbased universally elemental pattern that can generate all known optimal patterns. The previously proposed Voronoibased approach can not be applied to prove the optimality of the new patterns due to their special features. We propose a new deploymentpolygon based methodology. We prove the optimality of deployment patterns to achieve threeconnectivity, fourconnectivity and fiveconnectivity for certain ranges of Rc/Rs, respectively, and prove the optimality of deployment patterns to achieve sixconnectivity under all ranges of Rc/Rs.
On Connectivity in Ad Hoc Network under Jamming Using Directional Antennas and Mobility
 In International Conference on Wired /Wireless Internet Communications, Lecture Notes in Computer Science
, 2004
"... Abstract. In this paper we investigate the problem of maintaining connectivity under jamming in multihop ad hoc wireless networks. Connectivity is measured using a connectivity index, which indicates the probability that there exists a path between two nodes. We first show that connectivity can be d ..."
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Cited by 32 (1 self)
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Abstract. In this paper we investigate the problem of maintaining connectivity under jamming in multihop ad hoc wireless networks. Connectivity is measured using a connectivity index, which indicates the probability that there exists a path between two nodes. We first show that connectivity can be drastically reduced with a relatively small number of jammers. We show that using sectored antennas can maintain connectivity in the presence of a significantly higher number of jammers at the expense of higher average number of hops. Finally, we show that mobility allows further resiliency to jamming. 1
MAC vs. PC: Determinism and Randomness as Complementary Approaches to Robotic Exploration of Continuous Unknown Domains
, 2000
"... Three methods are described for exploring a continuous unknown planar region by a group of robots having limited sensors and no explicit communication. We formalize the problem, prove that its offline version is NPhard, and show a lower bound on the length of any solution. Then a deterministic mar ..."
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Cited by 22 (2 self)
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Three methods are described for exploring a continuous unknown planar region by a group of robots having limited sensors and no explicit communication. We formalize the problem, prove that its offline version is NPhard, and show a lower bound on the length of any solution. Then a deterministic mark and cover (MAC) algorithm is described for the online problem using shortlived navigational markers as means of navigation and indirect communication. The convergence of the algorithm is proved, and its cover time is shown to be the asymptotically optimal O(A/a), where A is the total area and a is the area covered by the robot in a single step. TheMAC algorithm is tested against an alternative randomized probabilistic covering (PC) method, which does not rely on sensors but is still able to cover an unknown region in an expected time that depends polynomially on the dimensions of the region. Both algorithms enable cooperation of several robots to achieve faster coverage. Finally, we show...
Local Broadcasting in the Physical Interference Model
, 2008
"... In this work we analyze the complexity of local broadcasting in the physical interference model. We present two distributed randomized algorithms: one that assumes that each node knows how many nodes there are in its geographical proximity, and another, which makes no assumptions about topology know ..."
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Cited by 22 (2 self)
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In this work we analyze the complexity of local broadcasting in the physical interference model. We present two distributed randomized algorithms: one that assumes that each node knows how many nodes there are in its geographical proximity, and another, which makes no assumptions about topology knowledge. We show that, if the transmission probability of each node meets certain characteristics, the analysis can be decoupled from the global nature of the physical interference model, and each node performs a successful local broadcast in time proportional to the number of neighbors in its physical proximity. We also provide worstcase optimality guarantees for both algorithms and demonstrate their behavior in average scenarios through simulations.
1 Energy Provisioning in Wireless Rechargeable Sensor Networks
"... Abstract—Wireless rechargeable sensor networks (WRSNs) have emerged as an alternative to solving the challenges of size and operation time posed by traditional batterypowered systems. In this paper, we study a WRSN built from the industrial wireless identification and sensing platform (WISP) and co ..."
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Cited by 21 (2 self)
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Abstract—Wireless rechargeable sensor networks (WRSNs) have emerged as an alternative to solving the challenges of size and operation time posed by traditional batterypowered systems. In this paper, we study a WRSN built from the industrial wireless identification and sensing platform (WISP) and commercial offtheshelf RFID readers. The paperthin WISP tags serve as sensors and can harvest energy from RF signals transmitted by the readers. This kind of WRSNs is highly desirable for indoor sensing and activity recognition, and is gaining attention in the research community. One fundamental question in WRSN design is how to deploy readers in a network to ensure that the WISP tags can harvest sufficient energy for continuous operation. We refer to this issue as the energy provisioning problem. Based on a practical wireless recharge model supported by experimental data, we investigate two forms of the problem: point provisioning and path provisioning. Point provisioning uses the least number of readers to ensure that a static tag placed in any position of the network will receive a sufficient recharge rate for sustained operation. Path provisioning exploits the potential mobility of tags (e.g., those carried by human users) to further reduce the number of readers necessary: mobile tags can harvest excess energy in powerrich regions and store it for later use in powerdeficient regions. Our analysis shows that our deployment methods, by exploiting the physical characteristics of wireless recharging, can greatly reduce the number of readers compared with those assuming traditional coverage models. I.
Optimized Broadcast Protocol for Sensor Networks,”
 IEEE Transaction on Computers, Vol
, 2005
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