Results 11 - 20 of 139

A Statistical Analysis of the Long-Run Node Spatial Distribution in Mobile Ad Hoc Networks

by Douglas M. Blough, Giovanni Resta, Paolo Santi , 2002
"... In this paper, we analyze the node spatial distribution of a mobile wireless ad hoc networks. Characterizing this distribution is of fundamental importance in the analysis of many relevant properties of mobile ad hoc networks, such as connectivity, average route length, and network capacity. In part ..."
Abstract - Cited by 42 (5 self) - Add to MetaCart
In this paper, we analyze the node spatial distribution of a mobile wireless ad hoc networks. Characterizing this distribution is of fundamental importance in the analysis of many relevant properties of mobile ad hoc networks, such as connectivity, average route length, and network capacity. In particular, we have investigated under what conditions the node spatial distribution resulting after a large number of mobility steps resembles the uniform distribution. This is motivated by the fact that the existing theoretical results concerning mobile ad hoc networks are based on this assumption. In order to test this hypothesis, we performed extensive simulations using two well-known mobility models: the random waypoint model, which resembles intentional movement, and a Brownian-like model, which resembles non-intentional movement. Our analysis has shown that in the Brownian-like motion the uniformity assumption does hold, and that the intensity of the concentration of nodes in the center of the deployment region that occurs in the random waypoint model heavily depends on the choice of some mobility parameters. For extreme values of these parameters, the uniformity assumption is impaired.
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Analytical Modeling and Mitigation Techniques for the Energy Hole

by Jian Li, Prasant Mohapatra - Problems in Sensor Networks,” Pervasive and Mobile Computing , 2007
"... In this paper we investigate the problem of uneven energy consumptions in a large class of many-to-one sensor networks. In a many-to-one sensor network, all sensor nodes generate constant bit rate (CBR) data and send them to a single sink via multihop transmissions. This type of sensor networks has ..."
Abstract - Cited by 37 (0 self) - Add to MetaCart
In this paper we investigate the problem of uneven energy consumptions in a large class of many-to-one sensor networks. In a many-to-one sensor network, all sensor nodes generate constant bit rate (CBR) data and send them to a single sink via multihop transmissions. This type of sensor networks has many potential applications such as environmental monitoring and data gathering. Based on the observation that sensor nodes sitting around the sink need to relay more traffic compared to other nodes in outer sub-regions, our analysis verifies that nodes in inner rings suffer much faster energy consumption rates (ECR) and thus have much shorter expected lifetime. We term this phenomenon of uneven energy consumption rates as the “energy hole ” problem, which may result in severe consequences such as early dysfunction of the entire network. We proposed an analytical modeling for this problem, which can help understand the relevance of different factors on energy consumption rate. Using this model, we study the effectiveness of several existing approaches towards mitigating the “energy hole ” problem, including deployment assistance, traffic compression and aggregation. We have used simulation results to validate our analysis. Index Terms Energy hole problem, many-to-one communication model, sensor networks, uneven energy consumption rate. I.
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A cellular learning automata based clustering algorithm for wireless sensor networks

by M. Esnaashari, M. R. Meybodi - Sensor Letters , 2008
"... In the first part of this paper, we propose a generalization of cellular learning automata (CLA) called irregular cellular learning automata (ICLA) which removes the restriction of rectangular grid structure in traditional CLA. In the second part of the paper, based on the proposed model a new clust ..."
Abstract - Cited by 24 (13 self) - Add to MetaCart
In the first part of this paper, we propose a generalization of cellular learning automata (CLA) called irregular cellular learning automata (ICLA) which removes the restriction of rectangular grid structure in traditional CLA. In the second part of the paper, based on the proposed model a new clustering algorithm for sensor networks is designed. The proposed clustering algorithm is fully distributed and the nodes in the network don't need to be fully synchronized with each other. The proposed clustering algorithm consists of two phases; initial clustering and reclustering. Unlike existing methods in which the reclustering phase is performed periodically on the entire network, reclustering phase in the proposed method is performed locally whenever it is needed. This results in a reduction in the consumed energy for reclustering phase and also allows reclustering phase to be performed as the network operates. The proposed clustering method in comparison to existing methods produces a clustering in which each cluster has higher number of nodes and higher residual energy for the cluster head. Local reclustering, higher residual energy in cluster heads and higher number of nodes in each cluster results in a network with longer lifetime. To evaluate the performance of the proposed algorithm several experiments have been conducted. The results of experiments have shown that the proposed clustering algorithm outperforms existing clustering methods in terms of quality of clustering measured by the total number of clusters, the number of sparse clusters and the remaining energy level of the cluster heads. Experiments have also shown that the proposed clustering algorithm in comparison to other existing methods prolongs the network lifetime.

Paradox of Shortest Path Routing for Large Multi-Hop Wireless Networks

by Sungoh Kwon, Ness B. Shroff , 2007
"... In this paper, we analyze the impact of straight line routing in large homogeneous multi-hop wireless networks. We estimate the nodal load, which is defined as the number of packets served at a node, induced by straight line routing. For a given total offered load on the network, our analysis shows ..."
Abstract - Cited by 23 (1 self) - Add to MetaCart
In this paper, we analyze the impact of straight line routing in large homogeneous multi-hop wireless networks. We estimate the nodal load, which is defined as the number of packets served at a node, induced by straight line routing. For a given total offered load on the network, our analysis shows that the nodal load at each node is a function of the node’s Voronoi cell, the node’s location in the network, and the traffic pattern specified by the source and destination randomness and straight line routing. The traffic pattern determines where the hot spot is created in the network, and straight line routing itself can balance the relay load in certain cases. In the asymptotic regime, each node’s probability that the node serves a packet arriving to the network can be approximated as the multiplication of a half length of its Voronoi cell perimeter and the probability density function that a packet goes through the node’s location. Both simulations and analysis confirm that this approximation converges to the exact value. The scaling order of network performance in our analysis is independent of traffic patterns generated by source-destination pair randomness, but for a given node the performance of each node is strongly related to the source-destination pair randomness.
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New metrics for dominating set based energy efficient activity scheduling in ad hoc networks

by Jamil A. Shaikh, Julio Solano, Ivan Stojmenovic, Jie Wu - In Proc. of the International Workshop on Wireless Local Networks (WLN , 2003
"... In a multi-hop wireless network, each node is able to send a message to all of its neighbors that are located within its transmission radius. In a flooding task, a source sends the same message to all the network. Routing problem deals with finding a route between a source and a destination. In the ..."
Abstract - Cited by 21 (16 self) - Add to MetaCart
In a multi-hop wireless network, each node is able to send a message to all of its neighbors that are located within its transmission radius. In a flooding task, a source sends the same message to all the network. Routing problem deals with finding a route between a source and a destination. In the activity-scheduling problem, each node decides between active or passive state. We present a scheme whose goal is to prolong network life while preserving connectivity. Each node is either active or has an active neighbor node. Routing and broadcasting are restricted to active nodes that create such dominating set. Activity status is periodically updated during a short transition period. The main contribution of this article is to propose new metrics for previously studied source-independent localized dominating sets, based on combinations of node degrees and remaining energy levels, for deciding activity status. 1.
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Maximizing network lifetime of broadcasting over wireless stationary ad hoc networks

by Intae Kang, Radha Poovendran - Mobile Networks and Applications (MONET), Special Issue on Energy Constraints and Lifetime Performance in Wireless Sensor Networks , 2005
"... Abstract — We investigate the problem of energy-efficient broadcast routing over stationary wireless adhoc networks where the host is not mobile. We define the lifetime of a network as the duration of time from the network initialization until the first node failure due to the battery exhaustion. We ..."
Abstract - Cited by 21 (0 self) - Add to MetaCart
Abstract — We investigate the problem of energy-efficient broadcast routing over stationary wireless adhoc networks where the host is not mobile. We define the lifetime of a network as the duration of time from the network initialization until the first node failure due to the battery exhaustion. We provide a globally optimal solution to the problem of maximizing a static network lifetime through a graph theoretic approach. We make use of this solution to develop a periodic tree update strategy for dynamic load balancing and show that a significant gain in network lifetime can be achieved. We also provide extensive comparative simulation studies on parameters that affect the lifetime of a network. I.
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Experimental evaluation of lifetime bounds for wireless sensor networks

by Hartmut Ritter, Jochen Schiller, Thiemo Voigt, Adam Dunkels, Juan Alonso - in Proc. EWSN 2005 , 2005
"... Abstract — In this paper we present a method for experimental lifetime measurements of sensor networks. Despite the importance of experimental validation, none of the lifetime models proposed so far has been validated experimentally. One of the reasons for the absence of practical validations might ..."
Abstract - Cited by 20 (4 self) - Add to MetaCart
Abstract — In this paper we present a method for experimental lifetime measurements of sensor networks. Despite the importance of experimental validation, none of the lifetime models proposed so far has been validated experimentally. One of the reasons for the absence of practical validations might be the long lifetime of batteries which make the validation of the proposed models non-trivial and time consuming. Our solution enables validation of lifetime models within a reasonable amount of time. We also use our method to validate a simple mathematical model that provides bounds on the lifetime of sensor networks. I.
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The Pulse Protocol: Energy Efficient Infrastructure Access

by Baruch Awerbuch, David Holmer, Herbert Rubens , 2004
"... We present the Pulse protocol which is designed for multi-hop wireless infrastructure access. While similar to the more traditional access point model, it is extended to operate across multiple hops. This is particularly useful for conference, airport, or large corporate deployments. In these types ..."
Abstract - Cited by 18 (4 self) - Add to MetaCart
We present the Pulse protocol which is designed for multi-hop wireless infrastructure access. While similar to the more traditional access point model, it is extended to operate across multiple hops. This is particularly useful for conference, airport, or large corporate deployments. In these types of environments where users are highly mobile, energy efficiency becomes of great importance. The Pulse protocol utilizes a periodic flood initiated at the network gateways which provides both routing and synchronization to the network. This synchronization is used to allow idle nodes to power off their radios for a large percentage of the time when they are not needed for packet forwarding. This results in substantial energy savings. Through simulation we validate the performance of the routing protocol with respect to both packet delivery and energy savings.

Rate allocation and network lifetime problems for wireless sensor networks

by Y. Thomas Hou, Senior Member, Yi Shi, Hanif D. Sherali - IEEE/ACM Trans. on Networking , 2008
"... Abstract—An important performance consideration for wire-less sensor networks is the amount of information collected by all the nodes in the network over the course of network lifetime. Since the objective of maximizing the sum of rates of all the nodes in the network can lead to a severe bias in ra ..."
Abstract - Cited by 18 (7 self) - Add to MetaCart
Abstract—An important performance consideration for wire-less sensor networks is the amount of information collected by all the nodes in the network over the course of network lifetime. Since the objective of maximizing the sum of rates of all the nodes in the network can lead to a severe bias in rate allocation among the nodes, we advocate the use of lexicographical max-min (LMM) rate allocation. To calculate the LMM rate allocation vector, we develop a polynomial-time algorithm by exploiting the parametric analysis (PA) technique from linear program (LP), which we call serial LP with Parametric Analysis (SLP-PA). We show that the SLP-PA can be also employed to address the LMM node lifetime problem much more efficiently than a state-of-the-art algorithm proposed in the literature. More important, we show that there exists an elegant duality relationship between the LMM rate allocation problem and the LMM node lifetime problem. Therefore, it is sufficient to solve only one of the two problems. Important insights can be obtained by inferring duality results for the other problem. Index Terms—Theory, sensor networks, energy constraint, network capacity, rate allocation, lexicographic max-min, node lifetime, linear programming, parametric analysis, flow routing. I.

Maximizing the lifetime of wireless sensor networks through optimal single-session flow routing

by Y. Thomas Hou, Yi Shi, Jianping Pan, Scott F. Midkiff - IEEE TRANS. ON MOBILE COMPUTING , 2006
"... Wireless sensor networks are becoming increasingly important in recent years due to their ability to detect and convey realtime, in-situ information for many civilian and military applications. A fundamental challenge for such networks lies in energy constraint, which poses a performance limit on th ..."
Abstract - Cited by 16 (4 self) - Add to MetaCart
Wireless sensor networks are becoming increasingly important in recent years due to their ability to detect and convey realtime, in-situ information for many civilian and military applications. A fundamental challenge for such networks lies in energy constraint, which poses a performance limit on the achievable network lifetime. We consider a two-tier wireless sensor network and address the network lifetime problem for upper-tier aggregation and forwarding nodes (AFNs). Existing flow routing solutions proposed for maximizing network lifetime require AFNs to split flows to different paths during transmission, which we call multisession flow routing solutions. If an AFN is equipped with a single transmitter/receiver pair, a multisession flow routing solution requires a packet-level power control at the AFN so as to conserve energy, which calls for considerable overhead in synchronization among the AFNs. In this paper, we show that it is possible to achieve the same optimal network lifetime by power control on a much larger timescale with the socalled single-session flow routing solutions, under which the packet-level power control and, thus, strict requirement on synchronization are not necessary. We also show how to perform optimal single-session flow routing when the bit-rate of composite flows generated by AFNs is time-varying, as long as the average bit-rate can be estimated.
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