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143
Message Delay in MANET
, 2005
"... A generic stochastic model with only two input parameters is introduced to evaluate the message delay in mobile ad hoc networks (MANETs) where nodes may relay messages. The LaplaceStieltjes transform (LST) of the message delay is obtained for two protocols: the twohop and the unrestricted multicop ..."
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Cited by 30 (0 self)
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A generic stochastic model with only two input parameters is introduced to evaluate the message delay in mobile ad hoc networks (MANETs) where nodes may relay messages. The LaplaceStieltjes transform (LST) of the message delay is obtained for two protocols: the twohop and the unrestricted multicopy protocol. From these results we deduce the expected message delays. It is shown that, despite its simplicity, the model accurately predicts the message delay under both relay strategies for a number of mobility models (the random waypoint, random direction and the random walker mobility models).
Modeling Spatial and Temporal Dependencies of User Mobility in Wireless Mobile Networks
"... Abstract—Realistic mobility models are fundamental to evaluate the performance of protocols in mobile ad hoc networks. Unfortunately, there are no mobility models that capture the nonhomogeneous behaviors in both space and time commonly found in reality, while at the same time being easy to use and ..."
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Abstract—Realistic mobility models are fundamental to evaluate the performance of protocols in mobile ad hoc networks. Unfortunately, there are no mobility models that capture the nonhomogeneous behaviors in both space and time commonly found in reality, while at the same time being easy to use and analyze. Motivated by this, we propose a timevariant community mobility model, referred to as the TVC model, which realistically captures spatial and time correlations. We achieve the goal with, on the one hand, the concept of communities that leads to skewed location visiting preferences, and, on the other hand, time periods that allow us to model time dependent behaviors and periodic reappearances of nodes at specific locations. To demonstrate the power and flexibility of the TVC model we use it to generate synthetic traces that match the characteristics of a number of qualitatively different mobility traces, including wireless LAN traces, vehicular mobility traces, and human encounter traces. More importantly, we show that, despite the high level of realism achieved, our TVC model is still theoretically tractable. To establish this, we derive a number of important quantities related to protocol performance, such as the nodal spatial distribution, the average node degree, and the hitting and meeting times for the TVC model, and provide examples of how to utilize this theory to guide design decisions in routing protocols. I.
Performance Analysis of Epidemic Routing under Contention
 IWCMC'06
, 2006
"... Epidemic routing has been proposed as a robust transmission scheme for sparse mobile ad hoc networks. Under the assumption of no contention, epidemic routing has the minimum endtoend delay amongst all the routing schemes proposed for such networks. The assumption of no contention was justified by ..."
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Cited by 20 (3 self)
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Epidemic routing has been proposed as a robust transmission scheme for sparse mobile ad hoc networks. Under the assumption of no contention, epidemic routing has the minimum endtoend delay amongst all the routing schemes proposed for such networks. The assumption of no contention was justified by arguing that since the network is sparse, there will be very few simultaneous transmissions. Some recent papers have shown through simulations that this argument is not correct and that contention cannot be ignored while analyzing the performance of routing schemes, even in sparse networks. Incorporating contention in the analysis has always been a hard problem and hence its effect has been studied mostly through simulations only. In this paper, we find analytical expressions for the delay performance of epidemic routing with contention. We include all the three main manifestations of contention, namely (i) the finite bandwidth of the link which limits the number of packets two nodes can exchange, (ii) the scheduling of transmissions between nearby nodes which is needed to avoid excessive interference, and (iii) the interference from transmissions outside the scheduling area. The accuracy of the analysis is verified via simulations.
Distributed Storage Management of Evolving Files in Delay Tolerant Ad Hoc Networks
"... Abstract — This work focuses on a class of distributed storage systems whose content may evolve over time. Each component or node of the storage system is mobile and the set of all nodes forms a delay tolerant (ad hoc) network (DTN). The goal of the paper is to study efficient ways for distributing ..."
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Abstract — This work focuses on a class of distributed storage systems whose content may evolve over time. Each component or node of the storage system is mobile and the set of all nodes forms a delay tolerant (ad hoc) network (DTN). The goal of the paper is to study efficient ways for distributing evolving files within DTNs and for managing dynamically their content. We specify to dynamic files where not only the latest version is useful but also previous ones; we restrict however to files where a file has no use if another more recent version is available. The DTN is composed of fixed number of nodes including a single source. At some points in time the source makes available a new version of a single file F. We consider both the cases when (a) nodes do not cooperate and (b) nodes cooperate. In case (a) only the source may transmit a copy of F to a node that it meets, while in case (b) any node may transmit a copy of F to a node that
Maximum Damage Malware Attack in Mobile Wireless Networks
"... Malware attacks constitute a serious security risk that threatens to slow down the large scale proliferation of wireless applications. As a first step towards thwarting this security threat, we seek to quantify the maximum damage inflicted on the system owing to such outbreaks and identify the most ..."
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Cited by 16 (2 self)
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Malware attacks constitute a serious security risk that threatens to slow down the large scale proliferation of wireless applications. As a first step towards thwarting this security threat, we seek to quantify the maximum damage inflicted on the system owing to such outbreaks and identify the most vicious attacks. We represent the propagation of malware in a batteryconstrained mobile wireless network by an epidemic model in which the worm can dynamically control the rate at which it kills the infected node and also the transmission range and/or the media scanning rate. At each moment of time, the worm at each node faces the following tradeoffs: (i) using larger transmission range and media scanning rate to accelerate its spread at the cost of exhausting the battery and thereby reducing the overall infection propagation rate in the long run or (ii) killing the node to inflict a large cost on the network, however at the expense of loosing the chance of infecting more susceptible nodes at later times. We mathematically formulate the decision problems and utilize Pontryagin Maximum Principle from optimal control theory to quantify the damage that the malware can inflict on the network by deploying optimum decision rules. Next, we establish structural properties of the optimal strategy of the attacker over time. Specifically, we prove that it is optimal for the attacker to defer killing of the infective nodes in the propagation phase until reaching a certain time and then start the slaughter with maximum effort. We also show that in the optimal attack policy, the battery resources are used according to a decreasing function of time, i.e., mostly during the initial phase of the outbreak. Finally, our numerical investigations reveal a framework for identifying intelligent defense strategies that can limit the damage by appropriately selecting network parameters.
GarciaLunaAceves, “Routing Overhead as A Function of Node Mobility: Modeling
 Framework and Implications on Proactive Routing,” Proc. of IEEE MASS’07
, 2007
"... Abstract—The paper presents a mathematical framework for quantifying the overhead of proactive routing protocols in mobile ad hoc networks (MANETs). We focus on situations where the nodes are randomly moving around but the wireless transmissions can be decoded reliablely, when nodes are within commu ..."
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Abstract—The paper presents a mathematical framework for quantifying the overhead of proactive routing protocols in mobile ad hoc networks (MANETs). We focus on situations where the nodes are randomly moving around but the wireless transmissions can be decoded reliablely, when nodes are within communication range of each other. We explicitly present a framework to model the overhead as a function of stability of topology and analytically characterize the statistical distribution of topology evolutions. The OLSR protocol is further singled out for a detailed analysis, incorporating the proposed analytical model. Results are compared against Qualnet simulations for random movements, which corroborate the essential characteristics of the analytical results. The key insight that can be drawn from the analytical results of this paper is that nodal movements will drive up the overhead by a penalty factor, which is a function of the overall stability of the network. I.
Performance Modeling of Network Coding in Epidemic Routing
 IN PROC. OF THE FIRST ACM INTERNATIONAL WORKSHOP ON MOBILE OPPORTUNISTIC NETWORKING (MOBIOPP
, 2007
"... Epidemic routing has been proposed to reduce the data transmission delay in opportunistic networks, in which data can be either replicated or network coded along the opportunistic multiple paths. In this paper, we introduce an analytical framework to study the performance of network coding based epi ..."
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Epidemic routing has been proposed to reduce the data transmission delay in opportunistic networks, in which data can be either replicated or network coded along the opportunistic multiple paths. In this paper, we introduce an analytical framework to study the performance of network coding based epidemic routing, in comparison with replication based epidemic routing. With extensive simulations, we show that our model successfully characterizes these two protocols and demonstrates the superiority of network coding in opportunistic networks when bandwidth and node buffers are limited. We then propose a priority variant of the network coding based protocol, which has the salient feature that the destination can decode a high priority subset of the data much earlier than it can decode any data without the priority scheme. Our analytical results provide insights into how network coding based epidemic routing with priority can reduce the data transmission delay while inducing low overhead.
Optimal Activation and Transmission Control in Delay Tolerant Networks ⋄
"... Abstract—Much research has been devoted to maximize the life time of mobile adhoc networks. Life time has often been defined as the time elapsed until the first node is out of battery power. In the context of static networks, this could lead to disconnectivity. In contrast, Delay Tolerant Networks ..."
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Cited by 14 (6 self)
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Abstract—Much research has been devoted to maximize the life time of mobile adhoc networks. Life time has often been defined as the time elapsed until the first node is out of battery power. In the context of static networks, this could lead to disconnectivity. In contrast, Delay Tolerant Networks (DTNs) leverage the mobility of relay nodes to compensate for lack of permanent connectivity, and thus enable communication even after some nodes deplete their stored energy. One can thus consider the lifetimes of nodes as some additional parameters that can be controlled to optimize the performance of a DTN. In this paper, we consider two ways in which the energy state of a mobile can be controlled. Both listening and transmission require energy, besides each of these has a different type of effect on the network performance. Therefore we consider a joint optimization problem consisting of: i) activation, which determines when a mobile will turn on in order to receive packets, and ii) transmission control, which regulates the beaconing. The optimal solutions are shown to be of the threshold type. The findings are validated through extensive simulations. Index Terms—Optimal control, fluid models, delay tolerant networks, threshold policies I.
A Framework for Opportunistic Forwarding in Disconnected Networks
 In Proc. of MOBIQUITOUS
, 2006
"... Abstract — In this paper, we analyze the performance of a family of opportunistic forwarding schemes (the Kcopy relaying strategies) over disconnected wireless networks. We introduce a classification of mobility models based on their dynamic properties, and characterize the M 2 (MarksMemoryless) c ..."
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Abstract — In this paper, we analyze the performance of a family of opportunistic forwarding schemes (the Kcopy relaying strategies) over disconnected wireless networks. We introduce a classification of mobility models based on their dynamic properties, and characterize the M 2 (MarksMemoryless) class. Statistical tools are combined with numerical simulations to show that some of the most used mobility models in the literature fall within the M 2 class. A mathematical framework is provided for evaluating the performance of opportunistic forwarding schemes in the presence of M 2 mobility, and it is shown that the finiteness of the mean time necessary to deliver a message depends only on the mobility characteristics and not on the relaying protocol specification. Index Terms — wireless networks, opportunistic forwarding, disconnected networks, mobility models. I.
Impact of Mobility on the Performance of Relaying in Ad Hoc Networks  Extended Version
"... We consider a mobile ad hoc network consisting of three types of nodes: source, destination, and relay nodes. All the nodes are moving over a bounded region with possibly different mobility patterns. We introduce and study the notion of relay throughput, i.e. the maximum rate at which a node can re ..."
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Cited by 13 (1 self)
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We consider a mobile ad hoc network consisting of three types of nodes: source, destination, and relay nodes. All the nodes are moving over a bounded region with possibly different mobility patterns. We introduce and study the notion of relay throughput, i.e. the maximum rate at which a node can relay data from the source to the destination. Our findings include the results that a) the relay throughput depends on the node mobility pattern only via its (stationary) node position distribution, and b) that a node mobility pattern that results in a uniform steadystate distribution for all nodes achieves the lowest relay throughput. Random Waypoint and Random Direction mobility models in both one and in two dimensions are studied and approximate simple expressions for the relay throughput are provided. Finally, the behavior of the relay buffer occupancy is examined for the Random Walk and Random Direction mobility models. For both models, the explicit form of the mean buffer are provided in the heavytraffic case.