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48
On connected multiple point coverage in wireless sensor networks
 Journal of Wireless Information Networks
, 2006
"... Abstract — We consider a wireless sensor network consisting of a set of sensors deployed randomly. A point in the monitored area is covered if it is within the sensing range of a sensor. In some applications, when the network is sufficiently dense, area coverage can be approximated by guaranteeing ..."
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Cited by 29 (0 self)
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Abstract — We consider a wireless sensor network consisting of a set of sensors deployed randomly. A point in the monitored area is covered if it is within the sensing range of a sensor. In some applications, when the network is sufficiently dense, area coverage can be approximated by guaranteeing point coverage. In this case, all the points of wireless devices could be used to represent the whole area, and the working sensors are supposed to cover all the sensors. Many applications related to security and reliability require guaranteed kcoverage of the area at all times. In this paper, we formalize the k(Connected) Coverage Set (kCCS/kCS) problems, develop a linear programming algorithm, and design two nonglobal solutions for them. Some theoretical analysis is also provided followed by simulation results. Index Terms — Coverage problem, linear programming, localized algorithms, reliability, wireless sensor networks.
Variable radii connected sensor cover in sensor networks
 in Proc. of the IEEE International Conference on Sensor and Ad Hoc Communications and Networks (SECON
, 2004
"... Abstract—One of the useful approaches to exploit redundancy in a sensor network is to keep active only a small subset of sensors that are sufficient to cover the region required to be monitored. The set of active sensors should also form a connected communication graph, so that they can autonomously ..."
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Cited by 25 (2 self)
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Abstract—One of the useful approaches to exploit redundancy in a sensor network is to keep active only a small subset of sensors that are sufficient to cover the region required to be monitored. The set of active sensors should also form a connected communication graph, so that they can autonomously respond to application queries and/or tasks. Such a set of active sensor is known as a connected sensor cover, and the problem of selecting a minimum connected sensor cover has been well studied when the transmission radius and sensing radius of each sensor is fixed. In this article, we address the problem of selecting a minimum energycost connected sensor cover, when each sensor node can vary its sensing and transmission radius; larger sensing or transmission radius entails higher energy cost. For the above problem, we design various centralized and distributed algorithms, and compare their performance through extensive experiments. One of the designed centralized algorithms (called CGA) is shown to perform within an O(log n) factor of the optimal solution, where n is the size of the network. We have also designed a localized algorithm based on Voronoi diagrams which is empirically shown to perform very close to CGA, and due to its communicationefficiency results in significantly prolonging the sensor network lifetime. I.
Analyzing the EnergyLatency Tradeoff during the Deployment of Sensor Networks
 In Proc. IEEE Infocom
, 2006
"... Abstract — The inherent tradeoff between energyefficiency and rapidity of event dissemination is characteristic for wireless sensor networks. Scarcity of energy renders it necessary for nodes to spend a large portion of their lifetime in an energyefficient sleep mode during which they do neither r ..."
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Cited by 23 (5 self)
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Abstract — The inherent tradeoff between energyefficiency and rapidity of event dissemination is characteristic for wireless sensor networks. Scarcity of energy renders it necessary for nodes to spend a large portion of their lifetime in an energyefficient sleep mode during which they do neither receive nor send messages. On the other hand, the longer nodes stay in sleep mode, the slower will be the reaction time for disseminating an external event. The tradeoff is prominently exhibited during the deployment phase of sensor networks, if some nodes are deployed earlier than others. In this paper, we study this fundamental tradeoff by giving a formal model that enables us to compare the performance of different protocols and algorithms. Based on this model, we propose, analyze, and simulate two novel algorithms which significantly outperform existing solutions. I.
Clustering wireless ad hoc networks with weakly connected dominating set
, 2007
"... The increasing popular personal communications and mobile computing require a wireless network infrastructure that supports selfconfiguration and selfmanagement. Efficient clustering protocol for constructing virtual backbone is becoming one of the most important issues in wireless ad hoc networks. ..."
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Cited by 17 (0 self)
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The increasing popular personal communications and mobile computing require a wireless network infrastructure that supports selfconfiguration and selfmanagement. Efficient clustering protocol for constructing virtual backbone is becoming one of the most important issues in wireless ad hoc networks. The weakly connected dominating set (WCDS) is very suitable for cluster formation. As finding the minimum WCDS in an arbitrary graph is a NPHard problem, we propose an areabased distributed algorithm for WCDS construction in wireless ad hoc networks with time and message complexity O(n). This Area algorithm is divided into three phases: area partition, WCDS construction for each area and adjustment along the area borders. We confirm the effectiveness of our algorithm through analysis and comprehensive simulation study. The number of nodes in the WCDS constructed by this Area algorithm is up to around 50 % less than that constructed by the previous wellknown algorithm.
Fault tolerant connected sensor cover with variable sensing and transmission ranges
 in IEEE SECON
, 2005
"... Abstract — Sensor networks are often deployed in a redundant fashion. In order to prolong the network lifetime, it is desired to choose only a subset of sensors to keep active and put the rest to sleep. In order to provide fault tolerance, this small subset of active sensors should also provide some ..."
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Cited by 15 (1 self)
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Abstract — Sensor networks are often deployed in a redundant fashion. In order to prolong the network lifetime, it is desired to choose only a subset of sensors to keep active and put the rest to sleep. In order to provide fault tolerance, this small subset of active sensors should also provide some degree of redundancy. In this paper, we consider the problem of choosing a minimum subset of sensors such that they maintain a required degree of coverage and also form a connected network with a required degree of fault tolerance. In addition, we consider a more general, variable radii sensor model, wherein every sensor can adjust both its sensing and transmission ranges to minimize overall energy consumption in the network. We call this the variable radii k1Connected, k2Cover problem. To address this problem, we propose a distributed and localized Voronoibased algorithm. The approach extends the relative neighborhood graph (RNG) structure to preserve kconnectivity in a graph, and design a distributed technique to inactivate desirable nodes while preserving kconnectivity of the remaining active nodes. We show through extensive simulations that our proposed techniques result in overall energy savings in random sensor networks over a wide range of experimental parameters. I.
Distributed Monitoring and Aggregation in Wireless Sensor Networks
"... Abstract — Selfmonitoring the sensor statuses such as liveness, node density and residue energy is critical for maintaining the normal operation of the sensor network. When building the monitoring architecture, most existing work focuses on minimizing the number of monitoring nodes. However, with l ..."
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Cited by 10 (1 self)
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Abstract — Selfmonitoring the sensor statuses such as liveness, node density and residue energy is critical for maintaining the normal operation of the sensor network. When building the monitoring architecture, most existing work focuses on minimizing the number of monitoring nodes. However, with less monitoring points, the false alarm rate may increase as a consequence. In this paper, we study the fundamental tradeoff between the number of monitoring nodes and the false alarm rate in the wireless sensor networks. Specifically, we propose fully distributed monitoring algorithms, to build up a pollerpollee based architecture with the objective to minimize the number of overall pollers while bounding the false alarm rate. Based on the established monitoring architecture, we further explore the hopbyhop aggregation opportunity along the multihop path from the polee to the poller, with the objective to minimize the monitoring overhead. We show that the optimal aggregation path problem is NPhard and propose an opportunistic greedy algorithm, which achieves an approximation ratio of 5 4.Asfar as we know, this is the first proved constant approximation ratio applied to the aggregation path selection schemes over the wireless sensor networks. I.
Regenerator placement with guaranteed connectivity in optical networks
, 2007
"... Abstract. The problem of minimizing the number of optical nodes with signal regeneration capability can be constrained to guarantee a desired degree of endtoend connectivity in the alloptical transport network. The problem can be formulated using a kconnected, kdominating node set, which is a k ..."
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Cited by 8 (3 self)
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Abstract. The problem of minimizing the number of optical nodes with signal regeneration capability can be constrained to guarantee a desired degree of endtoend connectivity in the alloptical transport network. The problem can be formulated using a kconnected, kdominating node set, which is a known approach in mobile ad hoc wireless networks. This paper presents a preliminary study aimed at establishing whether efficient centralized solutions to this problem in optical networking ought to be investigated to improve the decentralized solutions already available for wireless networks.
Incremental Construction of kDominating Sets in Wireless Sensor Networks
, 2006
"... Given a graph G, a kdominating set of G is a subset S of its vertices with the property that every vertex of G is either in S or has at least k neighbors in S. We present a new incremental local algorithm to construct a kdominating set. The algorithm constructs a monotone family of dominating sets ..."
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Cited by 7 (0 self)
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Given a graph G, a kdominating set of G is a subset S of its vertices with the property that every vertex of G is either in S or has at least k neighbors in S. We present a new incremental local algorithm to construct a kdominating set. The algorithm constructs a monotone family of dominating sets D1 ⊆ D2... ⊆ Di... ⊆ Dk such that each Di is an idominating set. For unit disk graphs, the size of each of the resulting idominating sets is at most six times the optimal. 1
On the construction of kconnected mdominating sets in wireless networks
 J COMB OPTIM
, 2012
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Techniques for maintaining connectivity in wireless adhoc networks under energy constraints
 ACM Transaction on Embedded Computing Systems
, 2007
"... Distributed wireless systems (DWSs) are emerging as the enabler for nextgeneration wireless applications. There is a consensus that DWSbased applications, such as pervasive computing, sensor networks, wireless information networks, and speech and data communication networks, will form the backbone ..."
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Cited by 4 (4 self)
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Distributed wireless systems (DWSs) are emerging as the enabler for nextgeneration wireless applications. There is a consensus that DWSbased applications, such as pervasive computing, sensor networks, wireless information networks, and speech and data communication networks, will form the backbone of the next technological revolution. Simultaneously, with great economic, industrial, consumer, and scientific potential, DWSs pose numerous technical challenges. Among them, two are widely considered as crucial: autonomous localized operation and minimization of energy consumption. We address the fundamental problem of how to maximize the lifetime of the network using only local information, while preserving network connectivity. We start by introducing the carefree sleep (CS) Theorem that provides provably optimal conditions for a node to go into sleep mode while ensuring that global connectivity is not affected. The CS theorem is the basis for an efficient localized algorithm that decides which nodes will go to into sleep mode and for how long. We have also developed mechanisms for collecting neighborhood information and for the coordination of distributed energy minimization protocols. The effectiveness of the approach is demonstrated using a comprehensive study of the performance of the algorithm over a wide range of network parameters. Another important highlight is the first mathematical and Monte Carlo analysis that establishes the importance of considering nodes within a small number of hops in order to preserve energy.