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61
Scheduling Algorithms for Multihop Radio Networks
 IEEE/ACM Transactions on Networking
, 1993
"... Abstructqew algorithms for transmission scheduling in multihop broadcast radio networks are presented. Both link scheduling and broadcast scheduling are considered. In each instance, scheduling algorithms are given that improve upon existing algorithms both theoretically and experimentally. Theore ..."
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Cited by 178 (1 self)
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Abstructqew algorithms for transmission scheduling in multihop broadcast radio networks are presented. Both link scheduling and broadcast scheduling are considered. In each instance, scheduling algorithms are given that improve upon existing algorithms both theoretically and experimentally. Theoretically, it is shown that tree networks can be scheduled optimally, and that arbitrary networks can be scheduled so that the schedule is bounded by a length that is proportional to a function of the network thickness times the optimum. Previous algorithms could guarantee only that the schedules were bounded by a length no worse than the maximum node degree times optimum. Since the thickness is typically several orders of magnitude less than the maximum node degree, the algorithms presented here represent a considerable theoretical improvement. Experimentally, a realistic model of a radio network is given and the performance of the new algorithms is studied. These results show that, for both types of scheduling, the new algorithms (experimentally) perform consistently better than earlier methods.
An Ω(D log(N/D)) Lower Bound for Broadcast in Radio Networks
 SIAM Journal on Computing
, 1998
"... Abstract. We show that for any randomized broadcast protocol for radio networks, there exists a network in which the expected time to broadcast a message is Ω(D log(N/D)), where D is the diameter of the network and N is the number of nodes. This implies a tight lower bound of Ω(D log N) for any D ≤ ..."
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Cited by 112 (4 self)
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Abstract. We show that for any randomized broadcast protocol for radio networks, there exists a network in which the expected time to broadcast a message is Ω(D log(N/D)), where D is the diameter of the network and N is the number of nodes. This implies a tight lower bound of Ω(D log N) for any D ≤ N 1−ε, where ε>0 is any constant.
On the complexity of computing minimum energy consumption broadcast subgraphs
 in Symposium on Theoretical Aspects of Computer Science
, 2001
"... Abstract. We consider the problem of computing an optimal range assignment in a wireless network which allows a specified source station to perform a broadcast operation. In particular, we consider this problem as a special case of the following more general combinatorial optimization problem, calle ..."
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Cited by 97 (11 self)
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Abstract. We consider the problem of computing an optimal range assignment in a wireless network which allows a specified source station to perform a broadcast operation. In particular, we consider this problem as a special case of the following more general combinatorial optimization problem, called Minimum Energy Consumption Broadcast Subgraph (in short, MECBS): Given a weighted directed graph and a specified source node, find a minimum cost range assignment to the nodes, whose corresponding transmission graph contains a spanning tree rooted at the source node. We first prove that MECBS is not approximable within a constant factor (unless P=NP). We then consider the restriction of MECBS to wireless networks and we prove several positive and negative results, depending on the geometric space dimension and on the distancepower gradient. The main result is a polynomialtime approximation algorithm for the NPhard case in which both the dimension and the gradient are equal to 2: This algorithm can be generalized to the case in which the gradient is greater than or equal to the dimension. 1
Fast Broadcasting and Gossiping in Radio Networks
, 2000
"... We establish an O(n log² n) upper bound on the time for deterministic distributed broadcasting in multihop radio networks with unknown topology. This nearly matches the known lower bound of n log n). The fastest previously known algorithm for this problem works in time O(n 3=2 ). Using our broa ..."
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Cited by 87 (6 self)
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We establish an O(n log² n) upper bound on the time for deterministic distributed broadcasting in multihop radio networks with unknown topology. This nearly matches the known lower bound of n log n). The fastest previously known algorithm for this problem works in time O(n 3=2 ). Using our broadcasting algorithm, we develop an O(n 3=2 log 2 n) algorithm for gossiping in the same network model.
Deterministic Radio Broadcasting
, 2000
"... We consider broadcasting in radio networks: one node of the network knows a message that needs to be learned by all the remaining nodes. We seek distributed deterministic algorithms to perform this task. Radio networks are modeled as directed graphs. They are unknown, in the sense that nodes are ..."
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Cited by 44 (11 self)
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We consider broadcasting in radio networks: one node of the network knows a message that needs to be learned by all the remaining nodes. We seek distributed deterministic algorithms to perform this task. Radio networks are modeled as directed graphs. They are unknown, in the sense that nodes are not assumed to know their neighbors, nor the size of the network, they are aware only of their individual identifying numbers. If more than one message is delivered to a node in a step then the node cannot hear any of them. Nodes cannot distinguish between such collisions and the case when no messages have been delivered in a step. The fastest previously known deterministic algorithm for deterministic distributed broadcasting in unknown radio networks was presented in [6], it worked in time O(n 11=6 ). We develop three new deterministic distributed algorithms. Algorithm A develops further the ideas of [6] and operates in time O(n 1:77291 ) = O(n 9=5 ), for general networks...
The wakeup problem in multihop radio networks
 in Proc., 15th ACMSIAM Symposium on Discrete Algorithms (SODA), 2004
, 2004
"... a wakeup signal from another node. Once a node is We study the problem of waking up a collection of activated, it starts executing its wakeup protocol. This processors connected by a multihop adhoc ratio network with unknown topology, no access to a global clock, and no collision detection mecha ..."
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Cited by 34 (6 self)
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a wakeup signal from another node. Once a node is We study the problem of waking up a collection of activated, it starts executing its wakeup protocol. This processors connected by a multihop adhoc ratio network with unknown topology, no access to a global clock, and no collision detection mechanism available. Each node in the network wakesup spontaneously, or it is activated by receiving a wakeup signal from another node. All active nodes transmit the wakeup signals according to a given protocol. The running time of is the number of steps counted from the first spontaneous wakeup, until all nodes become activated. We provide two protocols for this problem. The first one is a deterministic protocol with running time. Our protocol is based on a novel concept of a rotationtolerant
Efficient Communication Strategies for AdHoc Wireless Networks
, 2000
"... An adhoc wireless network is a collection of wireless mobile hosts forming a temporary network without the aid of any established infrastructure or centralized administration. This type of network is of great importance in situations where it is very difficult to provide the necessary infrastructur ..."
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Cited by 34 (3 self)
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An adhoc wireless network is a collection of wireless mobile hosts forming a temporary network without the aid of any established infrastructure or centralized administration. This type of network is of great importance in situations where it is very difficult to provide the necessary infrastructure, but it is a challenging task to enable fast and reliable communication within such a network. In this paper, we model and analyze the performance of socalled powercontrolled adhoc wireless networks: networks where the mobile hosts are able to change their transmission power. We concentrate on finding schemes for routing arbitrary permutations in these networks. In general, it is NPhard even to find a n 1 approximation for any constant to the fastest possible strategy for routing a given permutation problem on n mobile hosts. However, we here demonstrate that if we allow ourselves to consider slightly less general problems, efficient solutions can be found. We first demonstrate that there is a natural class of distributed schemes for handling nodetonode communication on top of which online route selection and scheduling strategies can be constructed such that the performance of this class of schemes can be exploited in a nearly optimal way for routing permutations in any static powercontrolled adhoc network. We then demonstrate
Deterministic Broadcasting in Ad Hoc Radio Networks
, 2002
"... We consider the problem of distributed deterministic broadcasting in radio networks of unknown topology and size. The network is synchronous. If a node u can be reached from two nodes which send messages in the same round, none of the messages is received by u. Such messages block each other and ..."
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Cited by 31 (2 self)
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We consider the problem of distributed deterministic broadcasting in radio networks of unknown topology and size. The network is synchronous. If a node u can be reached from two nodes which send messages in the same round, none of the messages is received by u. Such messages block each other and node u either hears the noise of interference of messages, enabling it to detect a collision, or does not hear anything at all, depending on the model. We assume that nodes know neither the topology nor the size of the network, nor even their immediate neighborhood. The initial knowledge of every node is limited to its own label. Such networks are called ad hoc multihop networks. We study the time of deterministic broadcasting under this scenario. For the model without collision detection, we develop a lineartime broadcasting algorithm for symmetric graphs, which is optimal, and an algorithm for arbitrary nnode graphs, working in time O(n 11=6 ). Next we show that broadcasting with acknowledgement is not possible in this model at all. For the model with collision detection, we develop ecient algorithms for broadcasting and for acknowledged broadcasting in strongly connected graphs. Key words: broadcasting, distributed, deterministic, radio network. Instytut Informatyki, Uniwersytet Warszawski, Banacha 2, 02097 Warszawa, Poland. Email: fchlebus,rytterg@mimuw.edu.pl y Department of Computer Science, The University of Liverpool, Liverpool L69 7ZF, United Kingdom. Email: fleszek,A.M.Gibbons,rytterg@csc.liv.ac.uk z Departement d'Informatique, Universite du Quebec a Hull, Hull, Quebec J8X 3X7, Canada. Email: Andrzej Pelc@uqah.uquebec.ca Research supported in part by NSERC grant OGP 0008136. This research was done during this author's stay at The Un...
Some Recent Theoretical Advances and Open Questions on Energy Consumption in AdHoc Wireless Networks
, 2002
"... One of the main benefits of power controlled adhoc wireless networks is their ability to vary the range in order to reduce the power consumption. Minimizing energy consumption is crucial on such kind of networks since, typically, wireless devices are portable and benefit only of limited power resou ..."
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Cited by 30 (9 self)
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One of the main benefits of power controlled adhoc wireless networks is their ability to vary the range in order to reduce the power consumption. Minimizing energy consumption is crucial on such kind of networks since, typically, wireless devices are portable and benefit only of limited power resources. On the other hand, the network must have a sufficient degree of connectivity in order to guarantee fast and efficient communication. These two aspects yield a class of fundamental optimization problems, denoted as range assignment problems, that have been the subject of several works in the area of wireless network theory. The primary aim of this paper is to describe the most important recent advances on this class of problems. Rather than completeness, the paper will try to provide results and techniques that seem to be the most promising to address the several important related problems which are still open. Discussing such related open problems are indeed our other main goal.
An approximation algorithm for the wireless gathering problem
 In Proc. 10th Scandinavian Workshop on Algorithm Theory
, 2006
"... Abstract. The Wireless Gathering Problem is to find a schedule for data gathering in a wireless static network. The problem is to gather a set of messages from the nodes in the network at which they originate to a central node, representing a powerful base station. The objective is to minimize the t ..."
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Cited by 29 (4 self)
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Abstract. The Wireless Gathering Problem is to find a schedule for data gathering in a wireless static network. The problem is to gather a set of messages from the nodes in the network at which they originate to a central node, representing a powerful base station. The objective is to minimize the time to gather all messages. The sending pattern or schedule should avoid interference of radio signals, which distinguishes the problem from wired networks. We study the Wireless Gathering Problem from a combinatorial optimization point of view in a centralized setting. This problem is known to be NPhard when messages have no release time. We consider the more general case in which messages may be released over time. For this problem we present a polynomialtime online algorithm which gives a 4approximation. We also show that within the class of shortest path following algorithms no algorithm can have approximation ratio better than 4. We also formulate some challenging open problems concerning complexity and approximability for variations of the problem. 1