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An evaluation of intervehicle ad hoc networks based on realistic vehicular traces, MobiHoc ’06:
 Proceedings of the 7th ACM international symposium on Mobile ad hoc networking and computing,
, 2006
"... ABSTRACT Vehicular ad hoc networks (VANETs) using WLAN technology have recently received considerable attention. The evaluation of VANET routing protocols often involves simulators since management and operation of a large number of real vehicular nodes is expensive. We study the behavior of routin ..."
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Cited by 149 (3 self)
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ABSTRACT Vehicular ad hoc networks (VANETs) using WLAN technology have recently received considerable attention. The evaluation of VANET routing protocols often involves simulators since management and operation of a large number of real vehicular nodes is expensive. We study the behavior of routing protocols in VANETs by using mobility information obtained from a microscopic vehicular traffic simulator that is based on the on the real road maps of Switzerland. The performance of AODV and GPSR is significantly influenced by the choice of mobility model, and we observe a significantly reduced packet delivery ratio when employing the realistic traffic simulator to control mobility of nodes. To address the performance limitations of communication protocols in VANETs, we investigate two improvements that increase the packet delivery ratio and reduce the delay until the first packet arrives. The traces used in this study are available for public download.
Distributed function calculation via linear iterations in the presence of malicious agents – part I: Attacking the network,” in
 Proc. of the American Control Conference,
, 2008
"... AbstractGiven a network of interconnected nodes, each with its own value (such as a measurement, position, vote, or other data), we develop a distributed strategy that enables some or all of the nodes to calculate any arbitrary function of the node values, despite the actions of malicious nodes in ..."
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Cited by 66 (5 self)
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AbstractGiven a network of interconnected nodes, each with its own value (such as a measurement, position, vote, or other data), we develop a distributed strategy that enables some or all of the nodes to calculate any arbitrary function of the node values, despite the actions of malicious nodes in the network. Our scheme assumes a broadcast model of communication (where all nodes transmit the same value to all of their neighbors) and utilizes a linear iteration where, at each timestep, each node updates its value to be a weighted average of its own previous value and those of its neighbors. We consider a node to be malicious or faulty if, instead of following the predefined linear strategy, it updates its value arbitrarily at each timestep (perhaps conspiring with other malicious nodes in the process). We show that the topology of the network completely characterizes the resilience of linear iterative strategies to this kind of malicious behavior. First, when the network contains 2f or fewer vertexdisjoint paths from some node xj to another node xi, we provide an explicit strategy for f malicious nodes to follow in order to prevent node xi from receiving any information about xj 's value. Next, if node xi has at least 2f + 1 vertexdisjoint paths from every other (nonneighboring) node, we show that xi is guaranteed to be able to calculate any arbitrary function of all node values when the number of malicious nodes is f or less. Furthermore, we show that this function can be calculated after running the linear iteration for a finite number of timesteps (upper bounded by the number of nodes in the network) with almost any set of weights (i.e., for all weights except for a set of measure zero).
Gossiping in a MultiChannel Radio Network  An Oblivious Approach to Coping with Malicious Interference (Extended Abstract)
 IN: DISC 2007. LNCS
, 2007
"... We study oblivious deterministic gossip algorithms for multichannel radio networks with a malicious adversary. In a multichannel network, each of the n processes in the system must choose, in each round, one of the c channels of the system on which to participate. Assuming the adversary can disrup ..."
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Cited by 38 (14 self)
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We study oblivious deterministic gossip algorithms for multichannel radio networks with a malicious adversary. In a multichannel network, each of the n processes in the system must choose, in each round, one of the c channels of the system on which to participate. Assuming the adversary can disrupt one channel per round, “preventing“ communication on that channel, we establish (1−ɛ)n a tight bound of max Θ c−1 + logc n n(1−ɛ), Θ ɛc2 ”” on the number of rounds needed to solve the ɛgossip problem, a parameterized generalization of the alltoall gossip problem that requires (1 − ɛ)n of the “rumors ” to be successfully disseminated. Underlying our lower bound proof lies an interesting connection between ɛgossip and extremal graph theory. Specifically, we make use of Turán’s theorem, a seminal result in extremal combinatorics, to reason about an adversary’s optimal strategy for disrupting an algorithm of a given duration. We then show how to generalize our upper bound to cope with an adversary that can simultaneously disrupt t < c channels. Our generalization makes use of selectors: a combinatorial tool that guarantees that any subset of processes will be “selected ” by some set in the selector. We prove this generalized algorithm optimal if a maximum number of values is to be gossiped. We conclude by extending our algorithm to tolerate traditional Byzantine corruption faults.
Of Malicious Motes and Suspicious Sensors  On the efficiency of malicious interference in wireless networks
, 2008
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Secure Communication over Radio Channels
 PODC'08
, 2008
"... We study the problem of secure communication in a multichannel, singlehop radio network with a malicious adversary that can cause collisions and spoof messages. We assume no preshared secrets or trustedthirdparty infrastructure. The main contribution of this paper is fAME: a randomized (f)ast( ..."
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Cited by 32 (13 self)
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We study the problem of secure communication in a multichannel, singlehop radio network with a malicious adversary that can cause collisions and spoof messages. We assume no preshared secrets or trustedthirdparty infrastructure. The main contribution of this paper is fAME: a randomized (f)ast(A)uthenticated (M)essage (E)xchange protocol that enables nodes to exchange messages in a reliable and authenticated manner. It runs in O(Et 2 log n) time and has optimal resilience to disruption, where E is the set of pairs of nodes that need to swap messages, n is the total number of nodes, C the number of channels, and t < C the number of channels on which the adversary can participate in each round. We show how to use fAME to establish a shared secret group key, which can be used to implement a secure, reliable and authenticated longlived communication service. The resulting service requires O(nt 3 log n) rounds for the setup phase, and O(t log n) rounds for an arbitrary pair to communicate. By contrast, existing solutions rely on preshared secrets, trusted thirdparty infrastructure, and/or the assumption that all interference is nonmalicious.
InterferenceResilient Information Exchange
"... This paper presents an efficient protocol to reliably exchange information in a singlehop radio network with unpredictable interference. The devices can access C communication channels. We model the interference with an adversary that can disrupt up to t of these channels simultaneously. We assume ..."
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Cited by 28 (12 self)
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This paper presents an efficient protocol to reliably exchange information in a singlehop radio network with unpredictable interference. The devices can access C communication channels. We model the interference with an adversary that can disrupt up to t of these channels simultaneously. We assume no shared secret keys or thirdparty infrastructure. The running time of our protocol decreases as the gap between C and t increases. Two extreme cases prove particularly interesting: The running time is linear when the number of channels C = Ω(t 2), and exponential when only C = t + 1 channels are available. We prove that exponentialtime is unavoidable in the latter case. At the core of our protocol lies a combinatorial function, of independent interest, and described for the first time in this paper: the multiselector. This function determines a sequence of device channel assignments such that every sufficiently large subset of devices is partitioned, by at least one of these assignments, onto distinct channels.
TimeEfficient Broadcast in Radio Networks
, 2010
"... Broadcasting is a basic network communication task, where a message initially held by a source node has to be disseminated to all other nodes in the network. Fast algorithms for broadcasting in radio networks have been studied in a wide variety of different models and under different requirements. S ..."
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Cited by 16 (0 self)
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Broadcasting is a basic network communication task, where a message initially held by a source node has to be disseminated to all other nodes in the network. Fast algorithms for broadcasting in radio networks have been studied in a wide variety of different models and under different requirements. Some of the main parameters giving rise to the different variants of the problem are the accessibility of knowledge about the network topology, the availability of collision detection mechanisms, the wakeup mode, the topology classes considered, and the use of randomness. This chapter introduces the problem, reviews the literature on timeefficient broadcasting algorithms for radio networks under a variety of models and assumptions, and illustrates some of the basic techniques.
Reliable Broadcast in Wireless Networks with Probabilistic Failures
 In Proceedings of the International Conference on Computer Communications (INFOCOM
, 2007
"... ..."
Discovering network topology in the presence of byzantine faults
 In 13th International Colloquium on Structural Information and Communication Complexity SIROCCO
, 2006
"... Abstract. We study the problem of Byzantinerobust topology discovery in an arbitrary asynchronous network. We formally state the weak and strong versions of the problem. The weak version requires that either each node discovers the topology of the network or at least one node detects the presence o ..."
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Cited by 12 (5 self)
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Abstract. We study the problem of Byzantinerobust topology discovery in an arbitrary asynchronous network. We formally state the weak and strong versions of the problem. The weak version requires that either each node discovers the topology of the network or at least one node detects the presence of a faulty node. The strong version requires that each node discovers the topology regardless of faults. We focus on noncryptographic solutions to these problems. We explore their bounds. We prove that the weak topology discovery problem is solvable only if the connectivity of the network exceeds the number of faults in the system. Similarly, we show that the strong version of the problem is solvable only if the network connectivity is more than twice the number of faults. We present solutions to both versions of the problem. The presented algorithms match the established graph connectivity bounds. The algorithms do not require the individual nodes to know either the diameter or the size of the network. The message complexity of both programs is low polynomial with respect to the network size. We describe how our solutions can be extended to add the property of termination, handle topology changes and perform neighborhood discovery. 1