Results 1  10
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31
Impact of human mobility on the design of opportunistic forwarding algorithms
 In Proc. IEEE Infocom
, 2006
"... Abstract — Studying transfer opportunities between wireless devices carried by humans, we observe that the distribution of the intercontact time, that is the time gap separating two contacts of the same pair of devices, exhibits a heavy tail such as one of a power law, over a large range of value. ..."
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Cited by 153 (9 self)
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Abstract — Studying transfer opportunities between wireless devices carried by humans, we observe that the distribution of the intercontact time, that is the time gap separating two contacts of the same pair of devices, exhibits a heavy tail such as one of a power law, over a large range of value. This observation is confirmed on six distinct experimental data sets. It is at odds with the exponential decay implied by most mobility models. In this paper, we study how this new characteristic of human mobility impacts a class of previously proposed forwarding algorithms. We use a simplified model based on the renewal theory to study how the parameters of the distribution impact the delay performance of these algorithms. We make recommendation for the design of well founded opportunistic forwarding algorithms, in the context of human carried devices. I.
Impact of human mobility on opportunistic forwarding algorithms
 IEEE Trans. Mob. Comp
, 2007
"... Abstract — We study data transfer opportunities between wireless devices carried by humans. We observe that the distribution of the intercontact time (the time gap separating two contacts between the same pair of devices) may be well approximated by a power law over the range [10 minutes; 1 day]. T ..."
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Cited by 122 (19 self)
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Abstract — We study data transfer opportunities between wireless devices carried by humans. We observe that the distribution of the intercontact time (the time gap separating two contacts between the same pair of devices) may be well approximated by a power law over the range [10 minutes; 1 day]. This observation is confirmed using eight distinct experimental data sets. It is at odds with the exponential decay implied by the most commonly used mobility models. In this paper, we study how this newly uncovered characteristic of human mobility impacts one class of forwarding algorithms previously proposed. We use a simplified model based on the renewal theory to study how the parameters of the distribution impact the performance in terms of the delivery delay of these algorithms. We make recommendations for the design of well founded opportunistic forwarding algorithms, in the context of human carried devices. I.
Delay and Capacity Tradeoffs in Mobile Ad Hoc Networks: A Global Perspective
"... Since the original work of Grossglauser and Tse, which showed that the mobility can increase the capacity of an ad hoc network, there has been a lot of interest in characterizing the delaycapacity relationship in ad hoc networks. Various mobility models have been studied in the literature, and the ..."
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Cited by 79 (1 self)
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Since the original work of Grossglauser and Tse, which showed that the mobility can increase the capacity of an ad hoc network, there has been a lot of interest in characterizing the delaycapacity relationship in ad hoc networks. Various mobility models have been studied in the literature, and the delaycapacity relationships under those models have been characterized. The results indicate that there are tradeoffs between the delay and the capacity, and that the nature of these tradeoffs is strongly influenced by the choice of the mobility model. Some questions that arise are: (i) How representative are these mobility models studied in the lieterature? (ii) Can the delaycapacity relationship be significantly different under some other “reasonable ” mobility model? (iii) What would the delaycapacity tradeoff in a real network be like? In this paper, we address these questions. In particular, we analyze, among others, some of the mobility models that have been used in the recent related works, under a unified framework. We relate the nature of the delaycapacity tradeoff to the nature of the node motion, thereby providing a better understanding of the delaycapacity relationship in ad hoc networks than earlier works.
Broadcast capacity in multihop wireless networks
 In MobiCom
, 2006
"... Abstract — In this paper we study the broadcast capacity of multihop wireless networks which we define as the maximum rate at which broadcast packets can be generated in the network such that all nodes receive the packets successfully within a given time. To asses the impact of topology and interfer ..."
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Cited by 73 (5 self)
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Abstract — In this paper we study the broadcast capacity of multihop wireless networks which we define as the maximum rate at which broadcast packets can be generated in the network such that all nodes receive the packets successfully within a given time. To asses the impact of topology and interference on the broadcast capacity we employ the Physical Model and Generalized Physical Model for the channel. Prior work was limited either by density constraints or by using the less realistic but manageable Protocol model [1], [2]. Under the Physical Model, we find that the broadcast capacity is within a constant factor of the channel capacity for a wide class of network topologies. Under the Generalized Physical Model, on the other hand, the network configuration is divided into three regimes depending on how the power is tuned in relation to network density and size and in which the broadcast capacity is asymptotically either zero, constant or unbounded. As we show, the broadcast capacity is limited by distant nodes in the first regime and by interference in the second regime. In the second regime, which covers a wide class of networks, the broadcast capacity is within a constant factor of the bandwidth. I.
Optimal ThroughputDelay Scaling in Wireless Networks  Part I: The Fluid Model
"... Gupta and Kumar (2000) introduced a random model to study throughput scaling in a wireless network with static nodes, and showed that the throughput per sourcedestination pair is Θ ( 1 / √ n log n). Grossglauser and Tse (2001) showed that when nodes are mobile it is possible to have a constant thr ..."
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Cited by 34 (0 self)
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Gupta and Kumar (2000) introduced a random model to study throughput scaling in a wireless network with static nodes, and showed that the throughput per sourcedestination pair is Θ ( 1 / √ n log n). Grossglauser and Tse (2001) showed that when nodes are mobile it is possible to have a constant throughput scaling per sourcedestination pair. In most applications delay is also a key metric of network performance. It is expected that high throughput is achieved at the cost of high delay and that one can be improved at the cost of the other. The focus of this paper is on studying this tradeoff for wireless networks in a general framework. Optimal throughputdelay scaling laws for static and mobile wireless networks are established. For static networks, it is shown that the optimal throughputdelay tradeoff is given by D(n) = Θ(nT (n)), where T (n) and D(n) are the throughput and delay scaling, respectively. For mobile networks, a simple proof of the throughput scaling of Θ(1) for the GrossglauserTse scheme is given and the associated delay scaling is shown to be Θ(n log n). The optimal throughputdelay tradeoff for mobile networks is also established. To capture physical movement in the real world, a random walk model for node mobility is assumed. It is shown that for throughput of O ( 1 / √ n log n) , which can also be achieved in static networks, the throughputdelay tradeoff is the same as in static networks, i.e., D(n) = Θ(nT (n)). Surprisingly, for almost any throughput of a higher order, the delay is shown to be Θ(n log n), which is the delay for throughput of Θ(1). Our result, thus, suggests that the use of mobility to increase throughput, even slightly, in realworld networks would necessitate an abrupt and very large increase in delay.
Optimal Geographic Routing for Wireless Networks with NearArbitrary Holes and Traffic
"... Abstract—We consider the problem of throughputoptimal routing over largescale wireless adhoc networks. Gupta and Kumar (2000) showed that a throughput capacity (a uniform 1) is achievable n log n rate over all sourcedestination pairs) of Θ( in random planar networks, and the capacity is achieved ..."
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Cited by 9 (3 self)
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Abstract—We consider the problem of throughputoptimal routing over largescale wireless adhoc networks. Gupta and Kumar (2000) showed that a throughput capacity (a uniform 1) is achievable n log n rate over all sourcedestination pairs) of Θ( in random planar networks, and the capacity is achieved by straightline routes. In reality, both the network model and the traffic demands are likely to be highly nonuniform. In this paper, we first propose a randomized forwarding strategy based on geographic routing that achieves nearoptimal throughput over random planar networks with an arbitrary number of routing holes (regions devoid of nodes) of varying sizes. Next, we study a random planar network with arbitrary sourcedestination pairs with arbitrary traffic demands. For such networks, we demonstrate a randomized local loadbalancing algorithm that supports any traffic load that is within a polylogarithmic factor of the throughput region. Our algorithms are based on geographic routing and hence inherit their advantageous properties of lowcomplexity, robustness and stability. I.
MultiChannel Wireless Networks: Capacity and Protocols
 University of Illinois
, 2001
"... Recent years have seen significant interest in using the multihop wireless networking paradigm for building mesh networks, ad hoc networks, and sensor networks. A key challenge in multihop wireless networks is to provision for sufficient network capacity to meet user requirements. Several approaches ..."
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Cited by 6 (1 self)
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Recent years have seen significant interest in using the multihop wireless networking paradigm for building mesh networks, ad hoc networks, and sensor networks. A key challenge in multihop wireless networks is to provision for sufficient network capacity to meet user requirements. Several approaches have been proposed to improve the network capacity in multihop networks, ranging from approaches that improve the efficiency of existing protocols, to approaches that use additional resources. In this dissertation, we propose to use additional frequency spectrum, as well as improve the efficiency of using existing frequency spectrum, for improving network capacity. Widely used wireless technologies, such as IEEE 802.11, provision for multiple frequencyseparated channels in the available frequency spectrum. Commercially available wireless network interfaces can typically operate over only one channel at a time. Due to cost and complexity constraints, the total number of interfaces at each node is expected to be fewer than the total number of channels available in the network. Under this scenario with fewer interfaces per node than channels, several challenges have to be addressed before all the channels can be utilized. In this dissertation, we have established the asymptotic capacity of multichannel wireless networks with varying number of channels and interfaces. Capacity analysis has shown that it is feasible
Secrecy throughput of manets with malicious nodes
 in ISIT 2009, 28 2009july 3 2009
"... Abstract—The secrecy throughput of mobile adhoc networks (MANETs) with malicious nodes is investigated. The MANET consists of n legitimate mobile nodes and m malicious nodes. Transmissions between legitimate nodes are subject to a delay constraint D. An information theoretic approach for security i ..."
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Cited by 5 (0 self)
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Abstract—The secrecy throughput of mobile adhoc networks (MANETs) with malicious nodes is investigated. The MANET consists of n legitimate mobile nodes and m malicious nodes. Transmissions between legitimate nodes are subject to a delay constraint D. An information theoretic approach for security is applied to achieve secure communication among legitimate nodes in MANETs with transmissions being kept perfectly secure from malicious nodes. A critical threshold on the number of malicious nodes (m) is identified such that when m = o ( √ nD), i.e., limn→ ∞ m / √ nD = 0, the secrecy throughput equals the throughput of MANETs without malicious nodes, i.e., the impact of the presence of malicious nodes ( on the network √nDpoly(n)) throughput is negligible; and when m = Ω, i.e., ( √nDpoly(n)) limn→ ∞ m/ ≥ c for a positive constant c, the secrecy throughput is limited by the number of malicious nodes. I.
Delay Guarantees for Throughputoptimal Wireless Link Scheduling
"... Abstract—We consider the question of obtaining tight delay guarantees for throughoutoptimal link scheduling in arbitrary topology wireless adhoc networks. We consider two classes of scheduling policies: 1) a maximum queuelength weighted independent set scheduling policy, and 2) a randomized indep ..."
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Cited by 4 (1 self)
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Abstract—We consider the question of obtaining tight delay guarantees for throughoutoptimal link scheduling in arbitrary topology wireless adhoc networks. We consider two classes of scheduling policies: 1) a maximum queuelength weighted independent set scheduling policy, and 2) a randomized independent set scheduling policy where the independent set scheduling probabilities are selected optimally. Both policies stabilize all queues for any set of feasible packet arrival rates, and are therefore throughputoptimal. For these policies and i.i.d. packet arrivals, we show that the average packet delay is bounded by a constant that depends on the chromatic number of the interference graph, and the overall load on the network. We also prove that this upper bound is asymptotically tight in the sense that there exist classes of topologies where the expected delay attained by any scheduling policy is lower bounded by the same constant. Through simulations we examine the scaling of the average packet delay with respect to the overall load on the network, and the chromatic number of the link interference graph. I.
Coding achieves the optimal delaythroughput tradeoffs in mobile adhoc networks
 in Proceedings of the IEEE International Symposium on Modeling and Optimization in Mobile, AdHoc and Wireless Networks (WiOpt
, 2007
"... Abstract — The delaythroughput tradeoff of a mobile wireless network under the twodimensional i.i.d mobility model has been investigated in [14], where we showed that the optimal tradeoff can be achieved using rateless codes. In this paper, we extend the result to a hybrid random walk model wit ..."
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Cited by 3 (1 self)
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Abstract — The delaythroughput tradeoff of a mobile wireless network under the twodimensional i.i.d mobility model has been investigated in [14], where we showed that the optimal tradeoff can be achieved using rateless codes. In this paper, we extend the result to a hybrid random walk model with fast mobiles. We first prove that the maximum throughput per sourcedestination (SD) pair is O ( √ D/n) when S = o(1) and D = ω(logS/S 2), and then propose a joint codingscheduling scheme to achieve the maximum throughput when S = o(1) and D is both ω(max{(log 2 n)logS/S 6, 3 √ nlogn}) and o(n/log 2 n), where n is the number of mobile nodes and S is the step size of the hybrid random walk. I. NOTATIONS The following notations are used throughout this paper, given nonnegative functions f(n) and g(n):