Results 1  10
of
27
A JammingResistant MAC Protocol for SingleHop Wireless Networks
, 2008
"... In this paper we consider the problem of designing a medium access control (MAC) protocol for singlehop wireless networks that is provably robust against adaptive adversarial jamming. The wireless network consists of a set of honest and reliable nodes that are within the transmission range of each ..."
Abstract

Cited by 28 (9 self)
 Add to MetaCart
In this paper we consider the problem of designing a medium access control (MAC) protocol for singlehop wireless networks that is provably robust against adaptive adversarial jamming. The wireless network consists of a set of honest and reliable nodes that are within the transmission range of each other. In addition to these nodes there is an adversary. The adversary may know the protocol and its entire history and use this knowledge to jam the wireless channel at will at any time. It is allowed to jam a (1 − ɛ)fraction of the time steps, for an arbitrary constant ɛ> 0, but it has to make a jamming decision before it knows the actions of the nodes at the current step. The nodes cannot distinguish between the adversarial jamming or a collision of two or more messages that are sent at the same time. We demonstrate, for the first time, that there is a localcontrol MAC protocol requiring only very limited knowledge about the adversary and the network that achieves a constant throughput for the nonjammed time steps under any adversarial strategy above. We also show that our protocol is very energy efficient and that it can be extended to obtain a robust and efficient protocol for leader election and the fair use of the wireless channel.
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 ..."
Abstract

Cited by 21 (7 self)
 Add to MetaCart
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.
Adversarial queuing on the multipleaccess channel
 In Proc. of PODC ’06
, 2006
"... We consider broadcasting on the multipleaccess channel when packets are injected continuously. Multipleaccess channel is a synchronous system with the properties that a single transmission at a round delivers the message to all nodes, while multiple simultaneous transmissions result in a conflict ..."
Abstract

Cited by 16 (8 self)
 Add to MetaCart
We consider broadcasting on the multipleaccess channel when packets are injected continuously. Multipleaccess channel is a synchronous system with the properties that a single transmission at a round delivers the message to all nodes, while multiple simultaneous transmissions result in a conflict which prevents delivering messages to any among the recipients. The traditional approach to dynamic broadcasting has been concerned with stability of protocols under suitable stochastic assumptions about injection rates. We study deterministic protocols competing against adversaries restricted by injection rate and burstiness of traffic. Stability means that the number of packets in queues is bounded by a constant in any execution, for a given number of stations, protocol, and adversary. Strong stability denotes the
Distributed coloring in O( √ log n) bit rounds
 In International Parallel & Distributed Processing Symposium (IPDPS
, 2006
"... We consider the wellknown vertex coloring problem: given a graph G, find a coloring of the vertices so that no two neighbors in G have the same color. It is trivial to see that every graph of maximum degree ∆ can be colored with ∆+1 colors, and distributed algorithms that find a (∆+1)coloring in a ..."
Abstract

Cited by 12 (1 self)
 Add to MetaCart
We consider the wellknown vertex coloring problem: given a graph G, find a coloring of the vertices so that no two neighbors in G have the same color. It is trivial to see that every graph of maximum degree ∆ can be colored with ∆+1 colors, and distributed algorithms that find a (∆+1)coloring in a logarithmic number of communication rounds, with high probability, are known since more than a decade. This is in general the best possible if only a constant number of bits can be sent along every edge in each round. In fact, we show that for the nnode cycle the bit complexity of the coloring problem is Ω(log n). More precisely, if only one bit can be sent along each edge in a round, then every distributed coloring algorithm (i.e., algorithms in which every node has the same initial state and initially only knows its own edges) needs at least Ω(log n) rounds, with high probability, to color the cycle, for any finite number of colors. But what if the edges have orientations, i.e., the endpoints of an edge agree on its orientation (while bits may still flow in both directions)? Does this allow one to provide faster coloring algorithms? Interestingly, for the cycle in which all edges have the same orientation, we show that a simple randomized algorithm can achieve a 3coloring with only O ( √ log n) rounds of bit transmissions, with high probability (w.h.p.). This re∗ Supported by NSF grant CCR0311121. † Partially supported by the DFGSonderforschungsbereich 376 and by the EU within 6th Framework Programme under contract 001907 Dynamically
A JammingResistant MAC Protocol for MultiHop Wireless Networks
, 2010
"... This paper presents a simple local medium access control protocol, called Jade, for multihop wireless networks with a single channel that is provably robust against adaptive adversarial jamming. The wireless network is modeled as a unit disk graph on a set of nodes distributed arbitrarily in the p ..."
Abstract

Cited by 12 (7 self)
 Add to MetaCart
This paper presents a simple local medium access control protocol, called Jade, for multihop wireless networks with a single channel that is provably robust against adaptive adversarial jamming. The wireless network is modeled as a unit disk graph on a set of nodes distributed arbitrarily in the plane. In addition to these nodes, there are adversarial jammers that know the protocol and its entire history and that are allowed to jam the wireless channel at any node for an arbitrary (1 − ɛ)fraction of the time steps, where 0 <ɛ<1 is an arbitrary constant. We assume that the nodes cannot distinguish between jammed transmissions and collisions of regular messages. Nevertheless, we show that Jade achieves an asymptotically optimal throughput if there is a sufficiently dense distribution of nodes.
Zero Preshared Secret Key Establishment in the Presence of Jammers
 ACM MOBIHOC'09
, 2009
"... We consider the problem of key establishment over a wireless radio channel in the presence of a communication jammer, initially introduced in [Strasser, Popper, Capkun & Cagalj]. The communicating nodes are not assumed to preshare any secret. The established key can later be used by a conventional ..."
Abstract

Cited by 8 (1 self)
 Add to MetaCart
We consider the problem of key establishment over a wireless radio channel in the presence of a communication jammer, initially introduced in [Strasser, Popper, Capkun & Cagalj]. The communicating nodes are not assumed to preshare any secret. The established key can later be used by a conventional spreadspectrum communication system. We introduce new communication concepts called intractable forwarddecoding and efficient backwarddecoding. Decoding under our mechanism requires at most twice the computation cost of the conventional SS decoding and one packet worth of signal storage. We introduce techniques that apply a key schedule to packet spreading and develop a provably optimal key schedule to minimize the bitdespreading cost. We also use efficient FFTbased algorithms for packet detection. We evaluate our techniques and show that they are efficient both in terms of resiliency against jammers and computation. Finally, our technique has additional features such as the inability to detect packet transmission until the last few bits are being transmitted, and transmissions being destinationspecific. To the best of our knowledge, this is the first solution that is optimal in terms of communication energy cost with very little storage and computation overhead.
Competitive and Fair Medium Access despite Reactive Jamming
"... Abstract—Intentional interference constitutes a major threat for communication networks operating over a shared medium where availability is imperative. Jamming attacks are often simple and cheap to implement. Today’s jammers can perform physical carrier sensing in order to disrupt communication mor ..."
Abstract

Cited by 8 (6 self)
 Add to MetaCart
Abstract—Intentional interference constitutes a major threat for communication networks operating over a shared medium where availability is imperative. Jamming attacks are often simple and cheap to implement. Today’s jammers can perform physical carrier sensing in order to disrupt communication more efficiently, especially in a network of simple wireless devices such as sensor nodes, which usually operate over a single frequency (or a limited frequency band) and which cannot benefit from the use of spread spectrum or other more advanced technologies. This paper proposes the medium access (MAC) protocol ANTIJAM which is provably robust against a powerful reactive adversary who can jam a (1 − ε)portion of the time steps, where ε is an arbitrary constant. The adversary uses carrier sensing to make informed decisions on when it is most harmful to disrupt communications. Moreover, we allow the adversary to be adaptive and to have complete knowledge of the entire protocol history. Our MAC protocol is able to make efficient use of the nonjammed time periods and achieves a Θ(1)competitive throughput in this harsh scenario, if ε is constant. In addition, ANTIJAM features a low convergence time and has excellent fairness properties in the sense that channel access probabilities among nodes do not differ by more than a small constant factor. I.
Consensus and mutual exclusion in a multiple access channel
 IEEE Transactions on Parallel and Distributed Systems
"... Abstract. We consider deterministic feasibility and time complexity of two fundamental tasks in distributed computing: consensus and mutual exclusion. Processes have different labels and communicate through a multiple access channel. The adversary wakes up some processes in possibly different rounds ..."
Abstract

Cited by 7 (3 self)
 Add to MetaCart
Abstract. We consider deterministic feasibility and time complexity of two fundamental tasks in distributed computing: consensus and mutual exclusion. Processes have different labels and communicate through a multiple access channel. The adversary wakes up some processes in possibly different rounds. In any round every awake process either listens or transmits. The message of a process i is heard by all other awake processes, if i is the only process to transmit in a given round. If more than one process transmits simultaneously, there is a collision and no message is heard. We consider three characteristics that may or may not exist in the channel: collision detection (listening processes can distinguish collision from silence), the availablity of a global clock showing the round number, and the knowledge of the number n of all processes. If none of the above three characteristics is available in the channel, we prove that consensus and mutual exclusion are infeasible; if at least one of them is available, both tasks are feasible and we study their time complexity. Collision detection is shown to cause an exponential gap in complexity: if it is available, both tasks can be performed in time logarithmic in n, which is optimal, and without collision detection both tasks require linear time. We then investigate both consensus and mutual exclusion in the absence of collision detection, but under alternative presence of the two other features. With global clock, we give an algorithm whose time complexity linearly depends on n and on the wakeup time, and an algorithm whose complexity does not depend on the wakeup time and differs from the linear lower bound only by a factor O(log 2 n). If n is known, we also show an algorithm whose complexity differs from the linear lower bound only by a factor O(log 2 n).
Adversarial Multiple Access Channel with Individual Injection Rates
"... Abstract. We study deterministic distributed broadcasting on a synchronous multipleaccess channel. Packets are injected into stations by a windowtype adversary that is constrained by an individual injection rate of each station and a window w. We investigate what queue sizes and packet latency can ..."
Abstract

Cited by 4 (2 self)
 Add to MetaCart
Abstract. We study deterministic distributed broadcasting on a synchronous multipleaccess channel. Packets are injected into stations by a windowtype adversary that is constrained by an individual injection rate of each station and a window w. We investigate what queue sizes and packet latency can be achieved with the maximum throughput of one packet per round. A protocol knows the number n of all the stations but does not know the window nor the individual rates of stations. We study the power of full sensing and acknowledgment based protocols as compared to general adaptive ones. We show that individual injection rates make it possible to achieve bounded packet latency by full sensing protocols, what is in contrast with the model of global injection rates for which stability and finite waiting times are not achievable together by general protocols. We show that packet latency is Ω ` ´ log n w when w ≤ n log w and it is Ω(w) when w> n. We give a full sensing protocol for channels with collision detection and an adaptive one for channels without collision detection that achieve O(min(n + w, w log n)) packet latency. We develop a full sensing protocol for a channel without collision detection that achieves O(n + w) queues and O(nw) packet latency. 1