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12
Realistic and Efficient MultiChannel Communications in Wireless Sensor Networks
"... Abstract—This paper demonstrates how to use multiple channels to improve communication performance in Wireless Sensor Networks (WSNs). We first investigate multichannel realities in WSNs through intensive empirical experiments with Micaz motes. Our study shows that current multichannel protocols a ..."
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Cited by 72 (3 self)
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Abstract—This paper demonstrates how to use multiple channels to improve communication performance in Wireless Sensor Networks (WSNs). We first investigate multichannel realities in WSNs through intensive empirical experiments with Micaz motes. Our study shows that current multichannel protocols are not suitable for WSNs, because of the small number of available channels and unavoidable time errors found in real networks. With these observations, we propose a novel treebased multichannel scheme for data collection applications, which allocates channels to disjoint trees and exploits parallel transmissions among trees. In order to minimize interference within trees, we define a new channel assignment problem which is proven NPcomplete. Then we propose a greedy channel allocation algorithm which outperforms other schemes in dense networks with a small number of channels. We implement our protocol, called TMCP, in a real testbed. Through both simulation and real experiments, we show that TMCP can significantly improve network throughput and reduce packet losses. More importantly, evaluation results show that TMCP better accommodates multichannel realities found in WSNs than other multichannel protocols. I.
Smartassoc: Decentralized access point selection algorithm to improve throughput,” under submission
"... Abstract—As the first step of the communication procedure in 802.11, an unwise selection of the Access Point (AP) hurts one client’s throughput. This performance downgrade is usually hard to be offset by other methods, such as efficient rate adaptations. In this article, we study this AP selection p ..."
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Cited by 7 (3 self)
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Abstract—As the first step of the communication procedure in 802.11, an unwise selection of the Access Point (AP) hurts one client’s throughput. This performance downgrade is usually hard to be offset by other methods, such as efficient rate adaptations. In this article, we study this AP selection problem in a decentralized manner, with the objective of maximizing the minimum throughput among all clients. We reveal through theoretical analysis that the selfish strategy, which commonly applies in decentralized systems, cannot effectively achieve this objective. Accordingly, we propose an online AP association strategy that not only achieves a minimum throughput (among all clients) that is provably close to the optimum, but also works effectively in practice with reasonable computation and transmission overhead. The association protocol applying this strategy is implemented on the commercial hardware and compatible with legacy APs without any modification. We demonstrate its feasibility and performance through real experiments and intensive simulations. Index Terms—AP association, wireless LAN, online algorithms, competitive ratio, minimum throughput maximization.
An Algorithm for Data Aggregation Scheduling with Longlifetime and Lowlatency in Wireless Sensor Networks
"... In scenarios of realtime data collection in longterm deployed Wireless Sensor Networks (WSNs), lowlatency data collection and long network lifetime become key issue. We propose a LongLifetime and LowLatency Data Aggregation Scheduling algorithm (L 4 DAS) in wireless sensor networks. Firstly, we ..."
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Cited by 3 (0 self)
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In scenarios of realtime data collection in longterm deployed Wireless Sensor Networks (WSNs), lowlatency data collection and long network lifetime become key issue. We propose a LongLifetime and LowLatency Data Aggregation Scheduling algorithm (L 4 DAS) in wireless sensor networks. Firstly, we formally formulate the problem of longlifetime and minimumlatency aggregation scheduling as a constrained optimization problem, and then propose an approximation algorithm for this problem by constructing a degreebounded minimum height spanning tree as aggregation tree and designing a maximum interference priority scheduling scheme to schedule the transmission of nodes in aggregation tree. Finally, through the simulation and comparisons, we prove the effectiveness of the algorithm.
On the construction of data aggregation tree with minimum energy cost in wireless sensor networks: NPcompleteness and approximation algorithms
 in Proc. INFOCOM
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Building Maximum Lifetime Shortest Path Data Aggregation Trees in Wireless Sensor Networks
 ACM Trans. Sens. Netw
"... In wireless sensor networks, the spanning tree is usually used as a routing structure to collect data. In some situations, nodes do innetwork aggregation to reduce transmissions, save energy, and maximize network lifetime. Because of the restricted energy of sensor nodes, how to build an aggregatio ..."
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Cited by 2 (0 self)
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In wireless sensor networks, the spanning tree is usually used as a routing structure to collect data. In some situations, nodes do innetwork aggregation to reduce transmissions, save energy, and maximize network lifetime. Because of the restricted energy of sensor nodes, how to build an aggregation tree of maximum lifetime is an important issue. It has been proved to be NPcomplete in previous works. As shortest path spanning trees intuitively have short delay, it is imperative to find an energyefficient shortest path tree for timecritical applications. In this article, we first study the problem of building maximum lifetime shortest path aggregation trees in wireless sensor networks. We show that when restricted to shortest path trees, building maximum lifetime aggregation trees can be solved in polynomial time. We present a centralized algorithm and design a distributed protocol for building such trees. Simulation results show that our approaches greatly improve the lifetime of the network and are very effective compared to other solutions. We extend our discussion to networks without aggregation and present interesting results.
Article Reliable Adaptive Data Aggregation Route Strategy for a Tradeoff between Energy and Lifetime in WSNs
, 2014
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A generalization of HopcroftKarp algorithm for semimatchings and covers in bipartite graphs
, 2012
"... An (f, g)semimatching in a bipartite graph G = (U ∪V,E) is a set of edges M ⊆ E such that each vertex u ∈ U is incident with at most f(u) edges of M, and each vertex v ∈ V is incident with at most g(v) edges of M. In this paper we give an algorithm that for a graph with n vertices and m edges, n ≤ ..."
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An (f, g)semimatching in a bipartite graph G = (U ∪V,E) is a set of edges M ⊆ E such that each vertex u ∈ U is incident with at most f(u) edges of M, and each vertex v ∈ V is incident with at most g(v) edges of M. In this paper we give an algorithm that for a graph with n vertices and m edges, n ≤ m, constructs a maximum (f, g)semimatching in running time O(m ·min( u∈U f(u), v∈V g(v))). Using the reduction of [5] our result on maximum (f, g)semimatching problem directly implies an algorithm for the optimal semimatching problem with running time O( nm log n).
1 SmartAssoc: Decentralized Access Point Selection Algorithm to Improve Throughput (Supplementary File)
"... In this supplementary file, we examine the network performance in terms of competitive ratio and convergence if selfish strategy is applied, and provide detailed proofs of theorems stated in the main manuscript. 1 SELFISH USER STRATEGY One natural alternative to solving the association problem, with ..."
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In this supplementary file, we examine the network performance in terms of competitive ratio and convergence if selfish strategy is applied, and provide detailed proofs of theorems stated in the main manuscript. 1 SELFISH USER STRATEGY One natural alternative to solving the association problem, with respect to our goal, is to let the clients behave myopically by applying in decentralized AP selection the bestreply policy. Explicitly, it means that every user keeps moving to associate with the AP that could offer it the best throughput until no user can gain higher throughput by unilaterally deviating from its current decision (Nash Equilibrium). To simplify the analysis for selfish users, we make two assumptions in this section. In the next section, we will use a more realistic assumptions. First, we assume that the interference between the communications of two APs is not considered, i.e., the nearby APs operate on orthogonal channels. Second, the association procedure of a user is considered as an atomic operation, so only one user performs the association at a time. The time at which a user makes a decision to change APs is marked as a decision step. However, we do not require users to follow a certain decision order, which means in each decision step the user who is picking a new AP could be any one.
Author manuscript, published in "17th IEEE Symposium on Computers and Communications, Turkey (2012)" A New Weighted Shortest Path Tree for Convergecast Traffic Routing in WSN
, 2012
"... Abstract—One of the widely used communication patterns in WSN is routing convergecast traffic to one or more sinks. In order to collect data at a sink, most existing systems use a tree rooted at the sink as underlying structure. We consider in this paper the Shortest Path routing Tree problem in WSN ..."
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Abstract—One of the widely used communication patterns in WSN is routing convergecast traffic to one or more sinks. In order to collect data at a sink, most existing systems use a tree rooted at the sink as underlying structure. We consider in this paper the Shortest Path routing Tree problem in WSN under different metrics; we show that the basic approach commonly used in the literature is unsuitable for the manytoone WSN when considering some metrics. Indeed, existing SPT approaches aim to construct a tree rooted at the sink such that the cost of the path from any node to the sink is minimal, while the cost of a given path is computed as summation of the costs of links that compose this path. However, in manytoone WSN, links which are close to the sink are more solicited to route packets towards the sink and, hence, they are more critical than other links. Therefore, links in the tree should not have the same weight. We propose in this paper a new weighted path cost function, and we show that our cost function is more suitable for WSN. Based on this cost function, we propose a new efficient shortest path tree construction which does not introduce any new communication overhead compared to basic SPT schemes. We consider, then, the particular case of energyaware routing in WSN when we apply our new solution in order to construct more suitable energyaware SPT. We conduct extensive simulations which show that our approach allows to enhance the network lifetime up to 20% compared to the basic one. Index Terms—Wireless Sensor Networks (WSN), Shortest Path Tree (SPT), weighted path cost function, energyaware routing.
Distributed optimization Estimation
, 2013
"... Distributed energyefficient estimation in spatially correlated wireless ..."
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