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141
Topological hole detection in wireless sensor networks and its applications
 In Proc. of Joint Workshop on Foundations of Mobile Computing (DIALMPOMC
, 2005
"... The identification of holes in a wireless sensor network is of primary interest since the breakdown of sensor nodes in a larger area often indicates one of the special events to be monitored by the network in the first place (e.g. outbreak of a fire, destruction by an earthquakes etc.). This task of ..."
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Cited by 52 (3 self)
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The identification of holes in a wireless sensor network is of primary interest since the breakdown of sensor nodes in a larger area often indicates one of the special events to be monitored by the network in the first place (e.g. outbreak of a fire, destruction by an earthquakes etc.). This task of identifying holes is especially challenging since typical wireless sensor networks consist of lightweight, lowcapability nodes that are unaware of their geographic location. But there is also a secondary interest in detecting holes in a network: recently routing schemes have been proposed that do not assume knowledge of the geographic location of the network nodes but rather perform routing decisions based on the topology of the communication graph. Holes are salient features of the topology of a communication graph. In the first part of this paper we propose a simple distributed procedure to identify nodes near the boundary of the sensor field as well as near hole boundaries. Our hole detection algorithm is based purely on the topology of the communication graph, i.e. the only information available is which nodes can communicate with each other. In the second part of this paper we illustrate the secondary interest of our hole detection procedure using several examples.
Fast Deterministic Distributed Maximal Independent Set Computation on GrowthBounded Graphs
 In Proc. of the 19th International Symposium on Distributed Computing (DISC
, 2005
"... Abstract. The distributed complexity of computing a maximal independent set in a graph is of both practical and theoretical importance. While there exists an elegant O(log n) time randomized algorithm for general graphs [20], no deterministic polylogarithmic algorithm is known. In this paper, we st ..."
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Cited by 48 (10 self)
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Abstract. The distributed complexity of computing a maximal independent set in a graph is of both practical and theoretical importance. While there exists an elegant O(log n) time randomized algorithm for general graphs [20], no deterministic polylogarithmic algorithm is known. In this paper, we study the problem in graphs with bounded growth, an important family of graphs which includes the wellknown unit disk graph and many variants thereof. Particularly, we propose a deterministic algorithm that computes a maximal independent set in time O(log ∆ · log∗n) in graphs with bounded growth, where n and ∆ denote the number of nodes and the maximal degree in G, respectively. 1
Modeling sensor networks
, 2008
"... In order to develop algorithms for sensor networks and in order to give mathematical correctness and performance proofs, models for various aspects of sensor networks are needed. This chapter presents and discusses currently used models for sensor networks. Generally, finding good models is a challe ..."
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Cited by 44 (5 self)
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In order to develop algorithms for sensor networks and in order to give mathematical correctness and performance proofs, models for various aspects of sensor networks are needed. This chapter presents and discusses currently used models for sensor networks. Generally, finding good models is a challenging task. On the one hand, a
Double Rulings for Information Brokerage in Sensor Networks
, 2006
"... We study the problem of information brokerage in sensor networks, where information consumers (sinks, users) search for data acquired by information producers (sources). Innetwork storage such as geographical hash table (GHT) has been proposed to store data at rendezvous nodes for consumers to ret ..."
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Cited by 43 (10 self)
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We study the problem of information brokerage in sensor networks, where information consumers (sinks, users) search for data acquired by information producers (sources). Innetwork storage such as geographical hash table (GHT) has been proposed to store data at rendezvous nodes for consumers to retrieve. In this paper, we propose a double rulings scheme which stores data replicas on a curve instead of one or multiple isolated sensors. The consumer travels along another curve which is guaranteed to intersect the producer curve. The double rulings is a natural extension of the flat hashing scheme such as GHTs. It has improved query locality, i.e., consumers close to producers find the data quickly, and structured aggregate queries, i.e., a consumer following a curve is able to retrieve all the data. Further, by the flexibility of retrieval mechanisms we have better routing robustness (as multiple retrieval paths are available) and data robustness against regional node failures. We show by simulation that the double rulings scheme provides reduced communication costs and more balanced traffic load on the sensors.
On routing with guaranteed delivery in threedimensional ad hoc wireless networks
 In Proceedings of the International Conference on Distributed Computing and Networking, volume 4904 of Lecture Notes in Computer Science
, 2008
"... We study the problem of routing in threedimensional ad hoc networks. We are interested in routing algorithms that guarantee delivery and are klocal, i.e., each intermediate node v’s routing decision only depends on knowledge of the labels of the source and destination nodes, of the subgraph induce ..."
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Cited by 42 (3 self)
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We study the problem of routing in threedimensional ad hoc networks. We are interested in routing algorithms that guarantee delivery and are klocal, i.e., each intermediate node v’s routing decision only depends on knowledge of the labels of the source and destination nodes, of the subgraph induced by nodes within distance k of v, and of the neighbour of v from which the message was received. We model a threedimensional ad hoc network by a unit ball graph, where nodes are points in threedimensional space, and for each node v, there is an edge between v and every node u contained in the unitradius ball centred at v. The question of whether there is a simple local routing algorithm that guarantees delivery in unit ball graphs has been open for some time. In this paper, we answer this question in the negative: we show that for any fixed k, there can be no klocal routing algorithm that guarantees delivery on all unit ball graphs. This result is in contrast with the twodimensional case, where 1local routing algorithms that guarantee delivery are known. Specifically, we show that guaranteed delivery is possible if the nodes of the unit ball graph are contained in a slab of thickness 1 / √ 2. However, there is no klocal routing algorithm that guarantees delivery for the class of unit ball graphs contained in thicker slabs, i.e., slabs of thickness 1 / √ 2+ɛ for some ɛ> 0. The algorithm for routing in thin slabs derives from a transformation of unit ball graphs contained in thin slabs into quasi unit
Local approximation schemes for ad hoc and sensor networks
 In Proc. 3rd Joint Workshop on Foundations of Mobile Computing (DialMPOMC
, 2005
"... We present two local approaches that yield polynomialtime approximation schemes (PTAS) for the Maximum Independent Set and Minimum Dominating Set problem in unit disk graphs. The algorithms run locally in each node and compute a (1 + ε)approximation to the problems at hand for any given ε> 0. ..."
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Cited by 40 (9 self)
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We present two local approaches that yield polynomialtime approximation schemes (PTAS) for the Maximum Independent Set and Minimum Dominating Set problem in unit disk graphs. The algorithms run locally in each node and compute a (1 + ε)approximation to the problems at hand for any given ε> 0. The time complexity of both algorithms is O(TMIS + log ∗n/εO(1)), where TMIS is the time required to compute a maximal independent set in the graph, and n denotes the number of nodes. We then extend these results to a more general class of graphs in which the maximum number of pairwise independent nodes in every rneighborhood is at most polynomial in r. Such graphs of polynomially bounded growth are introduced as a more realistic model for wireless networks and they generalize existing models, such as unit disk graphs or coverage area graphs.
An O(log n) Dominating Set Protocol for Wireless AdHoc Networks under the Physical Interference Model
, 2008
"... Dealing with interference is one of the primary challenges to solve in the design of protocols for wireless adhoc networks. Most of the work in the literature assumes localized or hopbased interference models in which the effect of interference is neglected beyond a certain range from the transmitt ..."
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Cited by 31 (3 self)
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Dealing with interference is one of the primary challenges to solve in the design of protocols for wireless adhoc networks. Most of the work in the literature assumes localized or hopbased interference models in which the effect of interference is neglected beyond a certain range from the transmitter. However, interference is a more complex phenomenon that cannot, in general, be captured by localized models, implying that protocols based on such models are not guaranteed to work in practice. This paper is the first to present and rigorously analyze a distributed dominating set protocol for wireless adhoc networks with O(1) approximation bound based on the physical interference model, which accounts for interference generated by all nodes in the network. The proposed protocol is fully distributed, randomized, and extensively uses physical carrier sensing to reduce message overhead. It does not need node identifiers or any kind of prior information about the system, and all messages are of constant size (in bits). We prove that, by appropriately choosing the threshold for physical carrier sensing, the protocol stabilizes within a logarithmic number of communication rounds, w.h.p., which is faster than the runtime of any known distributed protocol without prior knowledge about away collisions.
An algorithmic approach to geographic routing in ad hoc and sensor networks
 IEEE/ACM Trans. Netw
"... Abstract—The one type of routing in ad hoc and sensor networks that currently appears to be most amenable to algorithmic analysis is geographic routing. This paper contains an introduction to the problem field of geographic routing, presents a specific routing algorithm based on a synthesis of the g ..."
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Cited by 27 (0 self)
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Abstract—The one type of routing in ad hoc and sensor networks that currently appears to be most amenable to algorithmic analysis is geographic routing. This paper contains an introduction to the problem field of geographic routing, presents a specific routing algorithm based on a synthesis of the greedy forwarding and face routing approaches, and provides an algorithmic analysis of the presented algorithm from both a worstcase and an averagecase perspective. Index Terms—Algorithmic analysis, routing, stretch, wireless networks.
Messageefficient beaconless georouting with guaranteed delivery in wireless sensor ad hoc and actuator networks
 IEEE/ACM Transactions on Networking
, 2010
"... Abstract—Recently proposed beaconless georouting algorithms are fully reactive, with nodes forwarding packets without prior knowledge of their neighbors. However, existing approaches for recovery from local minima can either not guarantee delivery or they require the exchange of complete neighborhoo ..."
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Cited by 20 (2 self)
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Abstract—Recently proposed beaconless georouting algorithms are fully reactive, with nodes forwarding packets without prior knowledge of their neighbors. However, existing approaches for recovery from local minima can either not guarantee delivery or they require the exchange of complete neighborhood information. We describe two general methods that enable completely reactive face routing with guaranteed delivery. The Beaconless Forwarder Planarization (BFP) scheme finds correct edges of a local planar subgraph at the forwarder node without hearing from all neighbors. Face routing then continues properly. Angular Relaying determines directly the next hop of a face traversal. Both schemes are based on the Select and Protest principle. Neighbors respond according to a delay function, if they do not violate the condition for a planar subgraph construction. Protest messages are used to remove falsely selected neighbors that are not in the planar subgraph. We show that a correct beaconless planar subgraph construction is not possible without protests. We also show the impact of the chosen planar subgraph construction on the message complexity. This leads to the definition of the Circlunar Neighborhood Graph (CNG), a new proximity graph, that enables BFP with a bounded number of messages in the worst case, which is not possible when using the Gabriel graph (GG). The CNG is sparser than the GG, but this does not lead to a performance degradation. Simulation results show similar message complexities in the average case when using CNG and GG. Angular Relaying uses a delay function that is based on the angular distance to the previous hop. Simulation results show that in comparison to BFP more protests are used, but overall message complexity can be further reduced. I.
Bounds on the network coding capacity for wireless random networks
 In Proc. 3rd Workshop on Network Coding, Theory, and Applications
, 2007
"... Abstract — Recently, it has been shown that the max flow capacity can be achieved in a multicast network using network coding. In this paper, we propose and analyze a more realistic model for wireless random networks. We prove that the capacity of network coding for this model is concentrated around ..."
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Cited by 19 (3 self)
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Abstract — Recently, it has been shown that the max flow capacity can be achieved in a multicast network using network coding. In this paper, we propose and analyze a more realistic model for wireless random networks. We prove that the capacity of network coding for this model is concentrated around the expected value of its minimum cut. Furthermore, we establish upper and lower bounds for wireless nodes using Chernoff bounds. Our experiments show that our theoretical predictions are well matched by simulation results. I.