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65
EnergyEfficient Area Monitoring for Sensor Networks
 IEEE Computer
, 2004
"... t replaceable, so its energy is the most important system resourceespecially when the network operates in hostile or remote environments. The best method for conserving energy is to put as many sensors to sleep as possible. At the same time, however, the network must maintain its functional ..."
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Cited by 59 (1 self)
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t replaceable, so its energy is the most important system resourceespecially when the network operates in hostile or remote environments. The best method for conserving energy is to put as many sensors to sleep as possible. At the same time, however, the network must maintain its functionality through a connected subnetwork that lets the monitoring station communicate with any of the network's active sensors. Our group at the Fundamental Computer Science Laboratory of Lille (LIFL) is developing strategies for selecting and updating an energyefficient connected active sensor set that extends the network lifetime. We report optimizing solutions to three separate problems: . area coveragemaintaining full coverage of the monitoring area; . request spreadingbroadcasting from the monitoring station to the covering nodes; and . data aggregationtransmitting information from nodes to the monitoring center. Each sensor's monitoring area can be approximated as a
Power Optimization in FaultTolerant Topology Control Algorithms for Wireless Multihop Networks
 in Proceedings of the 9th Annual International Conference on Mobile Computing and Networking. 2003
, 2003
"... In ad hoc wireless networks, it is crucial to minimize power consumption while maintaining key network properties. This work studies power assignments of wireless devices that minimize power while maintaining kfault tolerance. Specifically, we require all links established by this power setting be ..."
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Cited by 56 (7 self)
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In ad hoc wireless networks, it is crucial to minimize power consumption while maintaining key network properties. This work studies power assignments of wireless devices that minimize power while maintaining kfault tolerance. Specifically, we require all links established by this power setting be symmetric and form a kvertex connected subgraph of the network graph. This problem is known to be NPhard. We show current heuristic approaches can use arbitrarily more power than the optimal solution. Hence, we seek approximation algorithms for this problem. We present three approximation algorithms. The first algorithm gives an O(kα)approximation where α is the best approximation factor for the related problem in wired networks (the best α so far is O(log k).) With a more careful analysis, we show our second (slightly more complicated) algorithm is an O(k)approximation. Our third algorithm assumes that the edge lengths of the network graph form a metric. In this case, we present simple and practical distributed algorithms for the cases of 2 and 3connectivity with constant approximation factors. We generalize this algorithm to obtain an O(k 2c+2)approximation for general kconnectivity (2 ≤ c ≤ 4 is the power attenuation exponent). Finally, we show that these approximation algorithms compare favorably with existing heuristics. We note that all algorithms presented in this paper can be used to minimize power while maintaining kedge connectivity with guaranteed approximation factors.
LowInterference Topology Control for Wireless Ad Hoc Networks
 ACM Wireless Networks
, 2005
"... supported by NSF CCR0311174. Abstract — Topology control has been well studied in wireless ad hoc networks. However, only a few topology control methods take into account the low interference as a goal of the methods. Some researchers tried to reduce the interference by lowering node energy consump ..."
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Cited by 56 (0 self)
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supported by NSF CCR0311174. Abstract — Topology control has been well studied in wireless ad hoc networks. However, only a few topology control methods take into account the low interference as a goal of the methods. Some researchers tried to reduce the interference by lowering node energy consumption (i.e. by reducing the transmission power) or by devising low degree topology controls, but none of those protocols can guarantee low interference. Recently, Burkhart et al. [?] proposed several methods to construct topologies whose maximum link interference is minimized while the topology is connected or is a spanner for Euclidean length. In this paper we give algorithms to construct a network topology for wireless ad hoc network such that the maximum (or average) link (or node) interference of the topology is either minimized or approximately minimized. Index Terms — Topology control, interference, wireless ad hoc networks.
Cooperative multihop broadcast for wireless networks
 IEEE J. Sel. Areas Commun
, 2004
"... Abstract—We address the minimumenergy broadcast problem under the assumption that nodes beyond the nominal range of a transmitter can collect the energy of unreliably received overheard signals. As a message is forwarded through the network, a node will have multiple opportunities to reliably recei ..."
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Cited by 44 (1 self)
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Abstract—We address the minimumenergy broadcast problem under the assumption that nodes beyond the nominal range of a transmitter can collect the energy of unreliably received overheard signals. As a message is forwarded through the network, a node will have multiple opportunities to reliably receive the message by collecting energy during each retransmission. We refer to this cooperative strategy as accumulative broadcast. We seek to employ accumulative broadcast in a large scale loosely synchronized, lowpower network. Therefore, we focus on distributed network layer approaches for accumulative broadcast in which loosely synchronized nodes use only local information. To further simplify the system architecture, we assume that nodes forward only reliably decoded messages. Under these assumptions, we formulate the minimumenergy accumulative broadcast problem. We present a solution employing two subproblems. First, we identify the ordering in which nodes should transmit. Second, we determine the optimum power levels for that ordering. While the second subproblem can be solved by means of linear programming, the ordering subproblem is found to be NPcomplete. We devise a heuristic algorithm to find a good ordering. Simulation results show the performance of the algorithm to be close to optimum and a significant improvement over the well known BIP algorithm for constructing energyefficient broadcast trees. We then formulate a distributed version of the accumulative broadcast algorithm that uses only local information at the nodes and has performance close to its centralized counterpart. Index Terms—Distributed algorithm, minimumenergy broadcast, reliable forwarding, wideband regime.
Fast distributed algorithm for convergecast in ad hoc geometric radio networks
 Proc. 2nd Int. Conf. on Wireless on Demand Network Systems and Service (WONS
, 2005
"... Abstract — Wireless ad hoc radio networks have gained a lot of attention in recent years. We consider geometric networks, where nodes are located in a euclidean plane. We assume that each node has a variable transmission range and can learn the distance to the closest neighbor. We also assume that n ..."
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Cited by 29 (0 self)
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Abstract — Wireless ad hoc radio networks have gained a lot of attention in recent years. We consider geometric networks, where nodes are located in a euclidean plane. We assume that each node has a variable transmission range and can learn the distance to the closest neighbor. We also assume that nodes have a special collision detection (CD) capability so that a transmitting node can detect a collision within its transmission range. We study the basic communication problem of collecting data from all nodes called convergecast. Recently, there appeared many new applications such as realtime multimedia, battlefield communications and rescue operations that impose stringent delay requirements on the convergecast time. We measure the latency of convergecast, that is the number of time steps needed to collect the data in any nnode network. We propose a very simple randomized distributed algorithm that has the expected running time O(log n). We also show that this bound is tight and any algorithm needs Ω(log n) time steps while performing convergecast in an arbitrary network. One of the most important problems in wireless ad hoc networks is to minimize the energy consumption, which maximizes the network lifetime. We study the tradeoff between the energy and the latency of convergecast. We show that our algorithm consumes at most O(n log n) times the minimum energy. We also demonstrate that for a line topology the minimum energy convergecast takes n − 1 time steps while any algorithm performing convergecast within O(log n) time steps requires Ω(n) times the minimum energy.
Minimum energy reliable paths using unreliable wireless links
 In ACM Mobihoc
, 2005
"... We address the problem of energyefficient reliable wireless communication in the presence of unreliable or lossy wireless link layers in multihop wireless networks. Prior work [1] has provided an optimal energy efficient solution to this problem for the case where link layers implement perfect rel ..."
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Cited by 24 (0 self)
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We address the problem of energyefficient reliable wireless communication in the presence of unreliable or lossy wireless link layers in multihop wireless networks. Prior work [1] has provided an optimal energy efficient solution to this problem for the case where link layers implement perfect reliability. However, a more common scenario — a link layer that is not perfectly reliable, was left as an open problem. In this paper we first present two centralized algorithms, BAMER and GAMER, that optimally solve the minimum energy reliable communication problem in presence of unreliable links. Subsequently we present a distributed algorithm, DAMER, that approximates the performance of the centralized algorithm and leads to significant performance improvement over existing singlepath or multipath based techniques. Categories and Subject Descriptors
MobilitySensitive Topology Control in Mobile Ad Hoc Networks
 Proc. IEEE Int’l Parallel and Distributed Processing Symp
, 2004
"... Abstract—In most existing localized topology control protocols for mobile ad hoc networks (MANETs), each node selects a few logical neighbors based on location information and uses a small transmission range to cover those logical neighbors. Transmission range reduction conserves energy and bandwidt ..."
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Cited by 24 (8 self)
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Abstract—In most existing localized topology control protocols for mobile ad hoc networks (MANETs), each node selects a few logical neighbors based on location information and uses a small transmission range to cover those logical neighbors. Transmission range reduction conserves energy and bandwidth consumption, while still maintaining network connectivity. However, the majority of these approaches assume a static network without mobility. In a mobile environment network connectivity can be compromised by two types of “bad ” location information: inconsistent information, which makes a node select too few logical neighbors, and outdated information, which makes a node use too small a transmission range. In this paper, we first show some issues in existing topology control. Then, we propose a mobilitysensitive topology control method that extends many existing mobilityinsensitive protocols. Two mechanisms are introduced: consistent local views that avoid inconsistent information and delay and mobility management that tolerate outdated information. The effectiveness of the proposed approach is confirmed through an extensive simulation study. Index Terms—Connectivity, mobile ad hoc networks (MANETs), mobility management, simulation, topology control, view consistency. æ 1
Energy efficient broadcast in wireless ad hoc networks with hitchhiking
 In IEEE INFOCOM
, 2004
"... Abstract. In this paper, we propose a novel concept called Hitchhiking in order to reduce the energy consumption of broadcast application for wireless networks. Hitchhiking takes advantage of the physical layer design that facilitates the combining of partial signals to obtain the complete informa ..."
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Cited by 22 (1 self)
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Abstract. In this paper, we propose a novel concept called Hitchhiking in order to reduce the energy consumption of broadcast application for wireless networks. Hitchhiking takes advantage of the physical layer design that facilitates the combining of partial signals to obtain the complete information. The concept of combining partial signals using maximal ratio combiner [15] has been used to improve the reliability of the communication link but has never been exploited to reduce energy consumption in broadcasting over wireless ad hoc networks. We study the advantage of Hitchhiking for the scenario when the transmission power level of nodes is fixed as well as the scenario when the nodes can adjust their power level. For both scenarios, we show that Hitchhiking is advantageous and have proposed algorithms to construct broadcast tree with Hitchhiking taken into consideration. For fixed transmission power case, we propose and analyze a centralized heuristic algorithm called SPWMH (Single Power Wireless Multicast with Hitchhiking) to construct a broadcast tree with minimum forwarding nodes. For the latter case, we propose a centralized heuristic algorithm called Wireless Multicast with Hitchhiking (WMH) to construct an energy efficient tree using Hitchhiking and also present a distributed version of the heuristic. We also evaluate the proposed heuristics through simulation. Simulation results show that Hitchhiking can reduce the transmission cost of broadcast by as much as 50%. Further, we propose and evaluate a protocol called Power Saving with Broadcast Tree (PSBT) that reduces energy consumption of broadcast by eliminating
RNG Relay Subset Flooding Protocols In Mobile AdHoc Networks
, 2003
"... In this paper, we study broadcasting protocols where nodes use some of their neighbors to forward messages. We propose a new protocol based on a variant of neighbor elimination scheme using RNG graph to ensure a full coverage of the network. The computation of RNG uses two kinds of distance: a geome ..."
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Cited by 18 (6 self)
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In this paper, we study broadcasting protocols where nodes use some of their neighbors to forward messages. We propose a new protocol based on a variant of neighbor elimination scheme using RNG graph to ensure a full coverage of the network. The computation of RNG uses two kinds of distance: a geometrical one and and neighborhoodbased distance that permits to use our protocol without positioning system. This protocol, called RRS for RNG Relay Subset, provides a selfselecting forwarding neighbor operating mode which guarantees a fair broadcast loading. In RRS a node v is a relay for a node u if and only if v is a neighbor of u and v has a RNGneighbor which is not covered by u transmission. Moreover, experiments with 802.11like MAC layer show that RRS is efficient.