Results 1  10
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30
Adversarial contention resolution for simple channels
 In: 17th Annual Symposium on Parallelism in Algorithms and Architectures
, 2005
"... This paper analyzes the worstcase performance of randomized backoff on simple multipleaccess channels. Most previous analysis of backoff has assumed a statistical arrival model. For batched arrivals, in which all n packets arrive at time 0, we show the following tight highprobability bounds. Rand ..."
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Cited by 34 (1 self)
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This paper analyzes the worstcase performance of randomized backoff on simple multipleaccess channels. Most previous analysis of backoff has assumed a statistical arrival model. For batched arrivals, in which all n packets arrive at time 0, we show the following tight highprobability bounds. Randomized binary exponential backoff has makespan Θ(nlgn), and more generally, for any constant r, rexponential backoff has makespan Θ(nlog lgr n). Quadratic backoff has makespan Θ((n/lg n) 3/2), and more generally, for r> 1, rpolynomial backoff has makespan Θ((n/lg n) 1+1/r). Thus, for batched inputs, both exponential and polynomial backoff are highly sensitive to backoff constants. We exhibit a monotone superpolynomial subexponential backoff algorithm, called loglogiterated backoff, that achieves makespan Θ(nlg lgn/lg lglgn). We provide a matching lower bound showing that this strategy is optimal among all monotone backoff algorithms. Of independent interest is that this lower bound was proved with a delay sequence argument. In the adversarialqueuing model, we present the following stability and instability results for exponential backoff and loglogiterated backoff. Given a (λ,T)stream, in which at most n = λT packets arrive in any interval of size T, exponential backoff is stable for arrival rates of λ = O(1/lgn) and unstable for arrival rates of λ = Ω(lglgn/lg n); loglogiterated backoff is stable for arrival rates of λ = O(1/(lg lgnlgn)) and unstable for arrival rates of λ = Ω(1/lg n). Our instability results show that bursty input is close to being worstcase for exponential backoff and variants and that even small bursts can create instabilities in the channel.
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 ..."
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Cited by 29 (10 self)
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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.
Contention Resolution with Constant Expected Delay
"... We study contention resolution problem in a multipleaccess channel such as the Ethernet... ..."
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Cited by 26 (3 self)
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We study contention resolution problem in a multipleaccess channel such as the Ethernet...
Universal Continuous Routing Strategies
 IN PROC. OF THE 8TH ACM SYMP. ON PARALLEL ALGORITHMS AND ARCHITECTURES (SPAA
, 1996
"... In this paper we present routing protocols that are universal in the sense that they route messages along arbitrary (simple or shortest) paths in arbitrary networks. We study these protocols under a stochastic model of continuous message generation. The performance of such protocols is characterized ..."
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Cited by 25 (7 self)
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In this paper we present routing protocols that are universal in the sense that they route messages along arbitrary (simple or shortest) paths in arbitrary networks. We study these protocols under a stochastic model of continuous message generation. The performance of such protocols is characterized by three parameters: the maximum message generation rate for which the protocol is stable, the expected delay of a message from generation to service, and the time the protocol needs to recover from worst case scenarios. Our main results are a universal continuous storeandforward routing protocol and a universal continuous wormhole routing protocol. Both protocols yield significant performance improvements over all previously known continuous routing protocols. In addition, we present adaptations of our main results to continuous routing in nodesymmetric networks, butterflies, and meshes.
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 ..."
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Cited by 17 (8 self)
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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
Analysis of Practical Backoff Protocols for Contention Resolution with Multiple Servers
, 1995
"... Backoff protocols are probably the most widely used protocols for contention resolution in multiple access channels. In this paper, we analyze the stochastic behavior of backoff protocols for contention resolution among a set of clients and servers, each server being a multiple access channel that d ..."
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Cited by 16 (3 self)
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Backoff protocols are probably the most widely used protocols for contention resolution in multiple access channels. In this paper, we analyze the stochastic behavior of backoff protocols for contention resolution among a set of clients and servers, each server being a multiple access channel that deals with contention like an Ethernet channel. We use the standard model in which each client generates requests for a given server according to a Bernoulli distribution with a specified mean. The clientserver request rate of a system is the maximum over all clientserver pairs (i; j) of the sum of all request rates associated with either client i or server j. (Having a subunit clientserver request rate is a necessary condition for stability for singleserver systems.) Our main result is that any superlinear polynomial backoff protocol is stable for any multipleserver system with a subunit clientserver request rate. Our result is the first proof of stability for any backoff protocol fo...
Modeling parallel bandwidth: Local vs. global restrictions
"... Recently there has been an increasing interest in models of parallel computation that account for the bandwidth limitations in communication networks. Some models (e.g., bsp and logp) account for bandwidth limitations using a perprocessor parameter g> 1, such that eachpro cessor can send/receive at ..."
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Cited by 15 (4 self)
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Recently there has been an increasing interest in models of parallel computation that account for the bandwidth limitations in communication networks. Some models (e.g., bsp and logp) account for bandwidth limitations using a perprocessor parameter g> 1, such that eachpro cessor can send/receive at most h messages in g h time. Other models (e.g., pram(m)) account for bandwidth limitations as an aggregate parameter m<p, such thatthe p processors can send at most m messages in total at each step. This paper provides the rst detailed study of the algorithmic implications of modeling parallel bandwidth as a perprocessor (local) limitation versus an aggregate (global) limitation. We consider a number of basic problems
Randomized communication in radio networks
 HANDBOOK OF RANDOMIZED COMPUTING
, 2001
"... A communication network is called a radio network if its nodes exchange messages in the following restricted way. First, a send operation performed by a node delivers copies of the same message to all directly reachable nodes. Secondly, a node can successfully receive an incoming message only if exa ..."
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Cited by 14 (0 self)
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A communication network is called a radio network if its nodes exchange messages in the following restricted way. First, a send operation performed by a node delivers copies of the same message to all directly reachable nodes. Secondly, a node can successfully receive an incoming message only if exactly one of its neighbors sent a message in that step. It is this semantics of how ports at nodes send and receive messages that defines the networks rather than the fact that only radio waves are used as a medium of communication; but if that is the case then just a single frequency is used. We discuss algorithmic aspects of exchanging information in such networks, concentrating on distributed randomized protocols. Specific problems and solutions depend a lot on the topology of the underlying reachability graph and how much the nodes know about it. In singlehop networks each pair of nodes can communicate directly. This kind of networks is also known as the multiple access channel. Popular
A bound on the capacity of backoff and acknowledgementbased protocols
, 2003
"... We study contentionresolution protocols for multipleaccess channels. We show that every backoff protocol is transient if the arrival rate, λ, is at least 0.42 and that the capacity of every backoff protocol is at most 0.42. Thus, we show that backoff protocols have (provably) smaller capacity than ..."
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Cited by 12 (0 self)
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We study contentionresolution protocols for multipleaccess channels. We show that every backoff protocol is transient if the arrival rate, λ, is at least 0.42 and that the capacity of every backoff protocol is at most 0.42. Thus, we show that backoff protocols have (provably) smaller capacity than fullsensing protocols. Finally, we show that the corresponding results, with the larger arrival bound of 0.531, also hold for every acknowledgementbased protocol.
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 ..."
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Cited by 12 (7 self)
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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.