Results 1  10
of
17
A sublinear time distributed algorithm for minimumweight spanning trees
 SIAM J. Comput
, 1998
"... (Extended Abstract) ..."
Faultlocal distributed mending
 In Proceedings of the 14th Annual ACM Symposium on Principles of Distributed Computing
, 1995
"... As communication networks grow, existing fault handling tools that involve global measures such as global timeouts or reset procedures become increasingly unaffordable, since their cost grows with the size of the network. Rather, for a fault handling mechanism to scale to large networks, its cost m ..."
Abstract

Cited by 63 (16 self)
 Add to MetaCart
As communication networks grow, existing fault handling tools that involve global measures such as global timeouts or reset procedures become increasingly unaffordable, since their cost grows with the size of the network. Rather, for a fault handling mechanism to scale to large networks, its cost must depend only on the number of failed nodes Žwhich, thanks to today’s technology, grows much more slowly than the networks.. Moreover, it should allow the nonfaulty regions of the networks to continue their operation even during the recovery of the faulty parts. This paper introduces the concepts fault locality and faultlocally mendable problems, which are problems for which there are correction algorithms Žapplied after faults. whose cost depends only on the Ž unknown. number of faults. We show that any inputoutput problem is faultlocally mendable. The solution involves a novel technique combining data structures and ‘‘local votes’ ’ among nodes, which may be of interest in itself. � 1999 Academic Press * Alexander Goldberg lecturer.
Efficient InterferenceAware TDMA Link Scheduling for Static Wireless Networks
 In ACM MobiCom
, 2006
"... We study efficient link scheduling for a multihop wireless network to maximize its throughput. Efficient link scheduling can greatly reduce the interference effect of closeby transmissions. Unlike the previous studies that often assume a unit disk graph model, we assume that different terminals cou ..."
Abstract

Cited by 49 (8 self)
 Add to MetaCart
We study efficient link scheduling for a multihop wireless network to maximize its throughput. Efficient link scheduling can greatly reduce the interference effect of closeby transmissions. Unlike the previous studies that often assume a unit disk graph model, we assume that different terminals could have different transmission ranges and different interference ranges. In our model, it is also possible that a communication link may not exist due to barriers or is not used by a predetermined routing protocol, while the transmission of a node always result interference to all nonintended receivers within its interference range. Using a mathematical formulation, we develop synchronized TDMA link schedulings that optimize the networking throughput. Specifically, by assuming known link capacities and link traffic loads, we study link scheduling under the RTS/CTS interference model and the protocol interference model with fixed transmission power. For both models, we present both efficient centralized and distributed algorithms that use time slots within a constant factor of the optimum. We also present efficient distributed algorithms whose performances are still comparable with optimum, but with much less communications. Our theoretical results are corroborated by extensive simulation studies.
Fast Distributed Construction of Small kDominating Sets and Applications
, 2000
"... This paper presents a fast distributed algorithm to compute a small kdominating set D (for any xed k) and its induced graph partition (breaking the graph into radius k clusters centered around the vertices of D). The time complexity of the algorithm is O(k log n). ..."
Abstract

Cited by 43 (7 self)
 Add to MetaCart
This paper presents a fast distributed algorithm to compute a small kdominating set D (for any xed k) and its induced graph partition (breaking the graph into radius k clusters centered around the vertices of D). The time complexity of the algorithm is O(k log n).
Planar Orientations with Low OutDegree and Compaction of Adjacency Matrices
 Theoretical Computer Science
, 1991
"... We consider the problem of orienting the edges of a planar graph in such a way that the outdegree of each vertex is minimized. If, for each vertex v, the outdegree is at most d, then we say that such an orientation is dbounded. We prove the following results: ffl Each planar graph has a 5bounde ..."
Abstract

Cited by 34 (3 self)
 Add to MetaCart
We consider the problem of orienting the edges of a planar graph in such a way that the outdegree of each vertex is minimized. If, for each vertex v, the outdegree is at most d, then we say that such an orientation is dbounded. We prove the following results: ffl Each planar graph has a 5bounded acyclic orientation, which can be constructed in linear time. ffl Each planar graph has a 3bounded orientation, which can be constructed in linear time. ffl A 6bounded acyclic orientation, and a 3bounded orientation, of each planar graph can each be constructed in parallel time O(log n log n) on an EREW PRAM, using O(n= log n log n) processors. As an application of these results, we present a data structure such that each entry in the adjacency matrix of a planar graph can be looked up in constant time. The data structure uses linear storage, and can be constructed in linear time. Department of Mathematics and Computer Science, University of California, Riverside, CA 92521. On...
Dynamic Networks are as fast as static networks
 In 29th Annual Symposium on Foundations of Computer Science
, 1988
"... This paper gives an efficient simulation to show that dynamic networks are as fast as static ones up to a constant multiplicative factor. That is, any task can be performed in a dynamic asynchronous network essentially as fast as in a static synchronous network. The simulation protocol is based on a ..."
Abstract

Cited by 25 (8 self)
 Add to MetaCart
This paper gives an efficient simulation to show that dynamic networks are as fast as static ones up to a constant multiplicative factor. That is, any task can be performed in a dynamic asynchronous network essentially as fast as in a static synchronous network. The simulation protocol is based on a new approach, perceiving "locality " as the key to fast adaptation to changes in network topology. The heart of our simulation is a new technique, called a dynamic synchronizer which achieves "local" simulation of a global "clock" in a dynamic asynchronous network. Using this result we obtain improved solutions to a number of well known problems on dynamic networks. It can also be used to improve the solution to certain static network problems. 1 Introduction The Dynamic Asynchronous network, where links may repeatedly fail and recover, is a realistic model of existing commercial communication networks, such the ARPANET [23]. Design and analysis of protocols for such networks is much more...
Deterministic Distributed Resource Discovery (Extended Abstract)
 In Nineteenth Annual ACM SIGACT/SIGOPS Symposium on Principles of Distributed Computing
, 2000
"... The resource discovery problem was introduced by HarcholBalter, Leighton and Lewin. They developed a randomized algorithm (for Akamai Technologies) for the problem in the weakly connected directed graph model. This model is a directed logical graph, that represents the nodes' \knowledge" about t ..."
Abstract

Cited by 13 (0 self)
 Add to MetaCart
The resource discovery problem was introduced by HarcholBalter, Leighton and Lewin. They developed a randomized algorithm (for Akamai Technologies) for the problem in the weakly connected directed graph model. This model is a directed logical graph, that represents the nodes' \knowledge" about the topology of the underlying communication network. An algorithm can increase the connectivity of the logical graph by learning more about the topology. On the other hand, the environment typically decreases the logical connectivity by introducing topological changes. The current paper proposes a deterministic algorithm for the problem in the same model, that is near optimal in all the measures: time, message, and communication complexities. Each previous algorithm had a complexity that was higher at least in one of the measures. Specically, previous deterministic solutions required either time linear in the diameter of the initial network, or communication complexity O(n 3 ) (with message complexity O(n 2 )), or message complexity O(jE 0 j log n) (where E 0 is the edge set of the initial graph). Compared to the main randomized algorithm of the HarcholBalter, Leighton, and Lewin, the time complexity is reduced from O(log 2 n) to O(log n log n), the message complexity from O(n log 2 n) to O(n log n log n), and the communication complexity from O(n 2 log 3 n) to O(jE 0 j log 2 n + n 2 log n). For the undirected case there existed a time optimal deterministic algorithm that can be translated into this model. We present algorithms that are optimal in the other two measures. Faculty of Industrial Engineering and Management, Technion, Haifa 32000, Israel. kutten@ie.technion.ac.il. y Department of Computer Science and Applied Mathema...
InterferenceAware Joint Routing and TDMA Link Scheduling for Static Wireless Networks
, 2007
"... We study efficient interferenceaware joint routing and TDMA link scheduling for a multihop wireless network to maximize its throughput. Efficient link scheduling can greatly reduce the interference effect of closeby transmissions. Unlike the previous studies that often assume a unit disk graph m ..."
Abstract

Cited by 13 (0 self)
 Add to MetaCart
We study efficient interferenceaware joint routing and TDMA link scheduling for a multihop wireless network to maximize its throughput. Efficient link scheduling can greatly reduce the interference effect of closeby transmissions. Unlike the previous studies that often assume a unit disk graph model, we assume that different terminals could have different transmission ranges and different interference ranges. In our model, it is also possible that a communication link may not exist due to barriers or is not used by a predetermined routing protocol, while the transmission of a node always result interference to all nonintended receivers within its interference range. Using a mathematical formulation, we develop interference aware joint routing and synchronized TDMA link schedulings that optimize the networking throughput subject to various constraints. Our linear programming formulation will find a flow routing whose achieved throughput is at least a constant fraction of the optimum, and the achieved fairness is also a constant fraction of the requirement. Then, by assuming known link capacities and link traffic loads, we study link scheduling under the RTS/CTS interference model and the protocol interference model with fixed transmission power. For both models, we present both efficient centralized and distributed algorithms that use time slots within a constant factor of the optimum. We also present efficient distributed algorithms whose performances are still comparable with optimum, but with much less communications. We prove that the timeslots needed by our faster distributed algorithms are only at most O(min(log n, log ψ)) for RTS/CTS interference model and protocol interference model. Our theoretical results are corroborated by extensive simulation studies.
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
Tight Fault Locality
 Proc. 36th IEEE Symposium on Foundations of Computer Science
, 1995
"... This paper lays a theoretical foundation for scaling fault tolerant tasks to large and diversified networks, such as the Internet. In such networks, there are always parts of the network that failed. On the other hand, various subtasks interest only parts of the network, and it is desirable that ..."
Abstract

Cited by 11 (2 self)
 Add to MetaCart
This paper lays a theoretical foundation for scaling fault tolerant tasks to large and diversified networks, such as the Internet. In such networks, there are always parts of the network that failed. On the other hand, various subtasks interest only parts of the network, and it is desirable that those parts, if nonfaulty, do not suffer from faults in other parts. Our approach is to refine the previously suggested notion of fault local algorithms (that was best suited for global tasks) for which the complexity of recovering was proportional to the number of faults. We refine this notion by introducing the concept of tight fault locality to deal with problems whose complexity (in the absence of faults) is sublinear in the size of the network. For a problem whose time complexity on an nnode network is T (n) (where possibly T (n) = o(n)), a tightly fault local algorithm recovers a legal global state in O(T (x)) time when the (unknown) number of faults is x.