Results 21 - 30
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100
Accuracy vs Lifetime: Linear Sketches for Appoximate Aggregate Range Queries in Sensor Networks
, 2004
"... Query processing in sensor networks is critical for several sensor based monitoring applications and poses several challenging research problems. The in--network aggregation paradigm in sensor networks provides a versatile approach for evaluating simple aggregate queries, in which an aggregation-- ..."
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Cited by 7 (3 self)
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Query processing in sensor networks is critical for several sensor based monitoring applications and poses several challenging research problems. The in--network aggregation paradigm in sensor networks provides a versatile approach for evaluating simple aggregate queries, in which an aggregation--tree is imposed on the sensor network that is rooted at the base--station and the data gets aggregated as it gets forwarded up the tree. In this paper we consider an two kinds of aggregate queries: value range queries that compute the number of sensors that report values in the given range, and location range queries that compute the sum of values reported by sensors in a given location range. Such queries can be answered by using the in--network aggregation approach where only sensors that fall within the range contribute to the aggregate being maintained. However it requires a separate aggregate to be computed and communicated for each query and hence does not scale well with the number of queries. Many
Cross-layer Optimization of Correlated Data Gathering in Wireless Sensor Networks
"... Abstract—We consider the problem of gathering correlated sensor data by a single sink node in a wireless sensor network. We assume that the sensor nodes are energy-constrained and design efficient distributed protocols to maximize the network lifetime. Many existing approaches focus on optimizing th ..."
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Abstract—We consider the problem of gathering correlated sensor data by a single sink node in a wireless sensor network. We assume that the sensor nodes are energy-constrained and design efficient distributed protocols to maximize the network lifetime. Many existing approaches focus on optimizing the routing layer only, but in fact the routing strategy is often coupled with power control in the physical layer and link access in the MAC layer. This paper represents a first effort on network lifetime maximization that jointly considers the three layers. We first assume that link access probabilities are known and consider the joint optimal design of power control and routing. We show that the formulated optimization problem is convex and propose a distributed algorithm, JRPA, for the solution. We also discuss the convergence of JRPA. When the optimal link access probabilities are unknown, as in many practical networks, we generalize the problem formulation to encompass all the three layers of routing, power control, and link-layer random access. In this case, the problem cannot be converted into a convex optimization problem, but there exists a duality gap when the Lagrangian dual method is employed. We propose an efficient heuristic algorithm, JRPRA, to solve the general problem, and show through numerical experiments that it can significantly narrow the gap between the computed and optimal solutions. Moreover, even without a priori knowledge of the best link access probabilities predetermined for JRPA, JRPRA achieves extremely competitive performance with JRPA. Other numerical results are provided to show the convergence of the algorithms and their advantages over existing solutions. I.
HMRP:HierarchyBased Multipath Routing Protocol for Wireless Sensor Networks
- Department of Appiled Internet Science, Hsing Kuo University of Management. Department of Appiled Internet Science, Hsing Kuo University of Management, Yuying St
, 2005
"... This work presents a Hierarchy-Based Multi-path Routing Protocol (HMRP) for wireless sensor networks. According to HMRP, the wireless sensor network is initially constructed as a layered network. Based on the layered network, sensor nodes have multipath routes to the sink node through candidate pare ..."
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Cited by 6 (1 self)
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This work presents a Hierarchy-Based Multi-path Routing Protocol (HMRP) for wireless sensor networks. According to HMRP, the wireless sensor network is initially constructed as a layered network. Based on the layered network, sensor nodes have multipath routes to the sink node through candidate parent nodes. The simulation results indicate that the proposed HMRP can increase the lifetime of sensor networks better than other clustering or tree-based protocols.
Distributed Minimum Energy Data Gathering and Aggregation in Sensor Networks
"... In this paper, we propose an effective distributed algorithm to solve the minimum energy data gathering (MEDG) problem in wireless sensor networks. The problem objective is to find an optimal transmission structure on the network graph, such that the total energy consumed by the sensor nodes is mini ..."
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Cited by 4 (0 self)
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In this paper, we propose an effective distributed algorithm to solve the minimum energy data gathering (MEDG) problem in wireless sensor networks. The problem objective is to find an optimal transmission structure on the network graph, such that the total energy consumed by the sensor nodes is minimized. We formulate the problem as a non-linear optimization problem. The formulation considers in-network data aggregation and respects the capacity of the wireless sharedmedium. We apply Lagrangian dualization technique on this formulation to obtain a subgradient algorithm for computing the optimal transmission structure. The subgradient algorithm is asynchronous and amenable to fully distributed implementations, which corresponds to the decentralized nature of sensor networks.
Tuning Protocols to Improve the Energy Efficiency of Sensornets
"... Energy efficiency is of critical importance in sensornets where the working life of wireless motes, and consequently the entire network, is limited by the finite energy capacity of batteries. Radio network activity typically dominates the energy consumption profile of motes running distributed appli ..."
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Cited by 4 (3 self)
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Energy efficiency is of critical importance in sensornets where the working life of wireless motes, and consequently the entire network, is limited by the finite energy capacity of batteries. Radio network activity typically dominates the energy consumption profile of motes running distributed applications, and hence represents the obvious target when attempting to use energy more frugally. Significant savings can be obtained by carefully tuning existing energy-ignorant protocols. Current practice in choosing parameters is generally based on experience, intuition, and trial and error. This approach rarely leads to the best choice. In this paper a novel method is presented through which the complex relationships between protocol parameters, network structure, application workload and observed network behaviour are understood and then tuned. 1
A Non_Ack Routing Protocol in Ad-hoc Wireless Sensor Networks
"... Abstract:- A wireless sensor network contains many sensor nodes in a certain sensing area. Every sensor node consists of a central processing unit, transmitting unit, receiving unit and power supply unit. In order to have efficient sensed messages, both the base station and sensor nodes have to comm ..."
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Cited by 4 (1 self)
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Abstract:- A wireless sensor network contains many sensor nodes in a certain sensing area. Every sensor node consists of a central processing unit, transmitting unit, receiving unit and power supply unit. In order to have efficient sensed messages, both the base station and sensor nodes have to communicate for each others as well. Therefore, a certain sensing area is divided into many sub-areas and every sensor node transmits its message to cluster head which, normally, will integrate and forward these messages to the base station. At the first step, set-up phase is applied to form clusters and to select cluster heads. During the second phase, the transmission phase, every sensor node received a message from another node has to transmit a confirmed message, acknowledgement (ACK), to ensure whether or not the data has been received which means every sensor node will dissipate much energy on transmitting and receiving. However, this paper proposes an adaptive routing protocol called Non_Ack in the Ad-hoc wireless sensor networks that is the data for every sensor node is transmitted directly to the cluster head and then forwards back to the base station. Some conditions for these sensor nodes with the sensed data directly transmitted without any acknowledgement may be failed so that this paper also considers as nodes fail to transmit the data back, the base station will be taken over for the network. By the consideration of these failure nodes, the base station will establish a binary tree for fault tolerance. A binary tree in the base station is also a big help for query-based routing protocol. Finally, simulation results
Contiguous Link Scheduling for Data Aggregation in Wireless Sensor Networks
, 2013
"... Wireless sensor networks (WSNs) consist of a large number of battery-powered wireless sensor nodes, and one key issue in WSNs is to reduce the energy consumption while maintaining the normal functions of WSNs. Data aggregation, as a typical operation in data gathering applications, can cause a lot ..."
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Cited by 4 (1 self)
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Wireless sensor networks (WSNs) consist of a large number of battery-powered wireless sensor nodes, and one key issue in WSNs is to reduce the energy consumption while maintaining the normal functions of WSNs. Data aggregation, as a typical operation in data gathering applications, can cause a lot of energy wastage since sensor nodes, when not receiving data, may keep in the listen state during the data collection process. To save this energy wastage, sleep scheduling algorithms can be used to turn the nodes to the sleep state when their radios are not in use and wake them up when necessary. In this paper, we identify the contiguous link scheduling problem in WSNs, in which each node is assigned consecutive time slots so that the node can wake up only once in a scheduling period to fulfil its data collection task. The objective of the problem is to find an interference-free link scheduling with the minimum number of time slots used. In virtue of the contiguous link scheduling, the energy consumption caused by nodes’ state transitions can be reduced. We prove the contiguous link scheduling problem in WSNs to be NP-complete, and then present efficient centralized and distributed algorithms with theoretical performance bounds in both homogeneous and heterogeneous networks. We also conduct simulation experiments that corroborate the theoretical results and demonstrate the efficiency of our proposed algorithms.
An online multipath routing algorithm for maximizing lifetime in wireless sensor networks
- in Sixth International Conference on Information Technology: New Generations, ITNG
, 2009
"... We address the maximum lifetime routing problem in wireless sensor networks, and present an online multipath routing algorithm. The proposed algorithm strives to maxi-mize the network lifetime metric by distributing the source-to-sink traffic for a given routing request along a set of paths. Fuzzy m ..."
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We address the maximum lifetime routing problem in wireless sensor networks, and present an online multipath routing algorithm. The proposed algorithm strives to maxi-mize the network lifetime metric by distributing the source-to-sink traffic for a given routing request along a set of paths. Fuzzy membership function is used for designing the edge weight function. Simulation results obtained under a variety of network scenarios show that the proposed multi-path scheme is able to achieve better lifetime results than those obtained by its predecessor single-path fuzzy routing scheme as well as by another well-known online routing scheme, namely the Online Maximum Lifetime heuristic.
Everywhere Sparse Approximately Optimal Minimum Energy Data Gathering and Aggregation in Sensor Networks
"... We consider two related data gathering problems for wireless sensor networks (WSNs). The MLDA problem is concerned with maximizing the system lifetime T so that we can perform T rounds of data gathering with in–network aggregation, given the initial available energy of the sensors. The M 2 EDA probl ..."
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Cited by 3 (0 self)
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We consider two related data gathering problems for wireless sensor networks (WSNs). The MLDA problem is concerned with maximizing the system lifetime T so that we can perform T rounds of data gathering with in–network aggregation, given the initial available energy of the sensors. The M 2 EDA problem is concerned with minimizing the maximum energy consumed by any one sensor when performing T rounds of data gathering with in–network aggregation, for a given T. We provide an effective algorithm for finding an everywhere sparse integral solution to the M 2 EDA problem which is within a factor of α = 1+4n/T of the optimum, where n is the number of nodes. A solution is everywhere sparse if the number of communication links for any subset X of nodes is O(X), in our case at most 4|X|. Since often T = ω(n), we obtain the first everywhere sparse, asymptotically optimal integral solutions to the M 2 EDA problem. Everywhere sparse solutions are desirable since then almost all sensors have small number of incident communication links and small overhead for maintaining state. We also show that the MLDA and M 2 EDA problems are essentially equivalent, in the sense that we can obtain an optimal fractional solution to an instance of the MLDA problem by scaling
Integer Maximum Flow in Wireless Sensor Networks with Energy Constraint
, 2008
"... We study the integer maximum flow problem on wireless sensor networks with energy constraint. In this problem, sensor nodes gather data and then relay them to a base station, before they run out of battery power. Packets are considered as integral units and not splittable. The problem is to find the ..."
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Cited by 3 (0 self)
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We study the integer maximum flow problem on wireless sensor networks with energy constraint. In this problem, sensor nodes gather data and then relay them to a base station, before they run out of battery power. Packets are considered as integral units and not splittable. The problem is to find the maximum data flow in the sensor network subject to the energy constraint of the sensors. We show that this integral version of the problem is strongly NP-complete and in fact APX-hard. It follows that the problem is unlikely to have a polynomial time approximation scheme. Even when restricted to graphs with concrete geometrically defined connectivity and transmission costs, the problem is still strongly NP-complete. We provide some interesting polynomial time algorithms that give good approximations for the general case nonetheless. For networks with bounded treewidth greater than two, we show that the problem is weakly NP-complete and provide pseudo-polynomial time algorithms. For a special case of graphs with treewidth two, we give a polynomial time algorithm.
