Showing papers on "Topology control published in 2005"

EECS: an energy efficient clustering scheme in wireless sensor networks

Abstract: Data gathering is a common but critical operation in many applications of wireless sensor networks. Innovative techniques that improve energy efficiency to prolong the network lifetime are highly required. Clustering is an effective topology control approach in wireless sensor networks, which can increase network scalability and lifetime. In this paper, we propose a novel clustering schema EECS for wireless sensor networks, which better suits the periodical data gathering applications. Our approach elects cluster heads with more residual energy through local radio communication while achieving well cluster head distribution; further more it introduces a novel method to balance the load among the cluster heads. Simulation results show that EECS outperforms LEACH significantly with prolonging the network lifetime over 35%.

A topology control approach for utilizing multiple channels in multi-radio wireless mesh networks

Abstract: We consider the channel assignment problem in a multi-radio wireless mesh network that involves assigning channels to radio interfaces for achieving efficient channel utilization. We propose the notion of a traffic-independent base channel assignment to ease coordination and enable dynamic, efficient and flexible channel assignment. We present a novel formulation of the base channel assignment as a topology control problem, and show that the resulting optimization problem is NP-complete. We then develop a new greedy heuristic channel assignment algorithm (termed CLICA) for finding connected, low interference topologies by utilizing multiple channels. Our extensive simulation studies show that the proposed CLICA algorithm can provide large reduction in interference (even with a small number of radios per node), which in turn leads to significant gains in both link layer and multihop performance in 802.11-based multi-radio mesh networks.

Design and analysis of an MST-based topology control algorithm

Abstract: In this paper, we present a minimum spanning tree (MST)-based algorithm, called local minimum spanning tree (LMST), for topology control in wireless multihop networks. In this algorithm, each node builds its LMST independently and only keeps on-tree nodes that are one-hop away as its neighbors in the final topology. We analytically prove several important properties of LMST: 1) the topology derived under LMST preserves the network connectivity; 2) the node degree of any node in the resulting topology is bounded by 6; and 3) the topology can be transformed into one with bidirectional links (without impairing the network connectivity) after removal of all unidirectional links. Simulation results show that LMST can increase the network capacity as well as reduce the energy consumption.

Networking wireless sensors

Abstract: 1. Introduction 2. Network deployment 3. Localization 4. Time synchronization 5. Wireless characteristics 6. Medium access and sleep scheduling 7. Sleep-based topology control 8. Energy-efficient and robust routing 9. Data-Centric networking 10. Transport reliability and congestion control 11. Conclusions.

Low-Interference Topology Control for Wireless Ad Hoc Networks.

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.

Algorithmic aspects of topology control problems for ad hoc networks

Abstract: Topology control problems are concerned with the assignment of power values to the nodes of an ad hoc network so that the power assignment leads to a graph topology satisfying some specified properties. This paper considers such problems under several optimization objectives, including minimizing the maximum power and minimizing the total power. A general approach leading to a polynomial algorithm is presented for minimizing maximum power for a class of graph properties called monotone properties. The difficulty of generalizing the approach to properties that are not monotone is discussed. Problems involving the minimization of total power are known to be NP-complete even for simple graph properties. A general approach that leads to an approximation algorithm for minimizing the total power for some monotone properties is presented. Using this approach, a new approximation algorithm for the problem of minimizing the total power for obtaining a 2-node-connected graph is developed. It is shown that this algorithm provides a constant performance guarantee. Experimental results from an implementation of the approximation algorithm are also presented.

Optimal base-station locations in two-tiered wireless sensor networks

Abstract: We consider generic two-tiered wireless sensor networks (WSNs) consisting of sensor clusters deployed around strategic locations, and base-stations (BSs) whose locations are relatively flexible. Within a sensor cluster, there are many small sensor nodes (SNs) that capture, encode, and transmit relevant information from a designated area, and there is at least one application node (AN) that receives raw data from these SNs, creates a comprehensive local-view, and forwards the composite bit-stream toward a BS. This paper focuses on the topology control process for ANs and BSs, which constitute the upper tier of two-tiered WSNs. Since heterogeneous ANs are battery-powered and energy-constrained, their node lifetime directly affects the network lifetime of WSNs. By proposing algorithmic approaches to locate BSs optimally, we can maximize the topological network lifetime of WSNs deterministically, even when the initial energy provisioning for ANs is no longer always proportional to their average bit-stream rate. The obtained optimal BS locations are under different lifetime definitions according to the mission criticality of WSNs. By studying intrinsic properties of WSNs, we establish the upper and lower bounds of maximal topological lifetime, which enable a quick assessment of energy provisioning feasibility and topology control necessity. Numerical results are given to demonstrate the efficacy and optimality of the proposed topology control approaches designed for maximizing network lifetime of WSNs.

Interference-aware topology control for wireless sensor networks

Abstract: Topology control has been well studied in wireless ad hoc networks. However, only a few topology control methods (e.g. (1)) take into account the low interference as a goal of the methods. Some researchers tried to indirectly reduce the interference by reducing the transmission power or by devising low degree topologies, but none of those protocols can guarantee low interference. In this paper we present several algorithms to construct network topologies such that the maximum (or average) link (or nodal) interference of the topology is either minimized or approximately minimized. The algorithms and definitions introduced in this paper are not based on any geometry information about the nodes and they work for any graph models of wireless communication. The theoretical results are corroborated by simulation studies.

A robust interference model for wireless ad-hoc networks

Abstract: Among the foremost goals of topology control in wireless ad-hoc networks is interference reduction. This paper presents a receiver-centric interference model featuring two main advantages over previous work. First, it reflects the fact that interference occurs at the intended receiver of a message. Second, the presented interference measure is robust with respect to addition or removal of single network nodes. Regarding both of these aspects our model intuitively corresponds to the behavior of interference in reality. Based on this interference model, we show that currently known topology control algorithms poorly reduce interference. Motivated by the observation that already one-dimensional network instances display the intricacy of the considered problem, we continue to focus on the so-called highway model. Setting out to analyze the special case of the exponential node chain, we eventually describe an algorithm guaranteeing to achieve a /spl I.nroot//spl Delta/-approximation (where n=4) of the optimal connectivity-preserving topology in the general highway model.

Maximizing system lifetime in wireless sensor networks

Abstract: Maximizing system lifetime in battery-powered wireless sensor networks with power aware topology control protocols and routing protocols has received intensive research. In the past, this problem has been mostly studied from the indirect perspective of energy conservation. Although this leads to solutions that help extend network lifetime, energy conservation is not the same problem as network lifetime maximization. Some researchers have formally studied network lifetime maximization problems, based on the assumption that energy is only consumed by packet transmission. However, it is well known that in many cases energy is significantly consumed during idle periods and overhearing. In this paper, we try to present a survey and formal analysis of a variety of network lifetime maximization problems in different energy consumption models. In particular, we identify different energy consumption models, define a variety of fundamental network lifetime maximization problems in individual energy consumption models, and formally analyze their complexities. Polynomial time algorithms are presented for tractable problems, and NP-hardness proofs are presented for intractable problems.

On the interdependence of distributed topology control and geographical routing in ad hoc and sensor networks

Abstract: Since ad hoc and sensor networks can be composed of a very large number of devices, the scalability of network protocols is a major design concern. Furthermore, network protocols must be designed to prolong the battery lifetime of the devices. However, most existing routing techniques for ad hoc networks are known not to scale well. On the other hand, the so-called geographical routing algorithms are known to be scalable but their energy efficiency has never been extensively and comparatively studied. In a geographical routing algorithm, data packets are forwarded by a node to its neighbor based on their respective positions. The neighborhood of each node is constituted by the nodes that lie within a certain radio range. Thus, from the perspective of a node forwarding a packet, the next hop depends on the width of the neighborhood it perceives. The analytical framework proposed in this paper allows to analyze the relationship between the energy efficiency of the routing tasks and the extension of the range of the topology knowledge for each node. A wider topology knowledge may improve the energy efficiency of the routing tasks but increases the cost of topology information due to signaling packets needed to acquire this information. The problem of determining the optimal topology knowledge range for each node to make energy efficient geographical routing decisions is tackled by integer linear programming. It is shown that the problem is intrinsically localized, i.e., a limited topology knowledge is sufficient to make energy efficient forwarding decisions. The leading forwarding rules for geographical routing are compared in this framework, and the energy efficiency of each of them is studied. Moreover, a new forwarding scheme, partial topology knowledge forwarding (PTKF), is introduced, and shown to outperform other existing schemes in typical application scenarios. A probe-based distributed protocol for knowledge range adjustment (PRADA) is finally introduced that allows each node to efficiently select online its topology knowledge range. PRADA is shown to rapidly converge to a near-optimal solution.

Localized topology control algorithms for heterogeneous wireless networks

Abstract: Most existing topology control algorithms assume homogeneous wireless networks with uniform maximal transmission power, and cannot be directly applied to heterogeneous wireless networks where the maximal transmission power of each node may be different. We present two localized topology control algorithms for heterogeneous networks: Directed Relative Neighborhood Graph (DRNG) and Directed Local Spanning Subgraph (DLSS). In both algorithms, each node independently builds its neighbor set by adjusting the transmission power, and defines the network topology by using only local information. We prove that: 1) both DRNG and DLSS can preserve network connectivity; 2) the out-degree of any node in the resulting topology generated by DRNG or DLSS is bounded by a constant; and 3) DRNG and DLSS can preserve network bi-directionality. Simulation results indicate that DRNG and DLSS significantly outperform existing topology control algorithms for heterogeneous networks in several aspects.

Localized LMST and RNG based minimum-energy broadcast protocols in ad hoc networks

Abstract: In the minimum energy broadcasting problem, each node adjusts its transmission power to minimize the total energy consumption while still guaranteeing the full coverage of the network. We consider both topology control and broadcast oriented protocols, for which all existing solutions require global network information. In this paper, we describe new localized protocols where nodes require only local informations about their neighborhood (distances or geographic positions). In addition to this, our protocols are shown experimentally to be comparable to the best known globalized BIP solution. Our solutions are based on the use of neighbor elimination scheme applied on the relative neighborhood graph (RNG) and local minimum spanning tree (LMST) which preserve connectivity and are defined in localized manner. Two variants are proposed, one with timeout applied on nodes receiving message from non-RNG (non-LMST) neighbor and retransmitting immediately otherwise (unless list of RNG or LMST neighbors in need of the message is empty), and one with timeout applied on all the nodes. We proved that LMST is a subset of RNG, which explains why LMST always performs better among the two.

Efficient gathering of correlated data in sensor networks

Abstract: In this paper, we design techniques that exploit data correlations in sensor data to minimize communication costs (and hence, energy costs) incurred during data gathering in a sensor network. Our proposed approach is to select a small subset of sensor nodes that may be sufficient to reconstruct data for the entire sensor network. Then, during data gathering only the selected sensors need to be involved in communication. The selected set of sensors must also be connected, since they need to relay data to the data-gathering node. We define the problem of selecting such a set of sensors as the connected correlation-dominating set problem, and formulate it in terms of an appropriately defined correlation structure that captures general data correlations in a sensor network.We develop a set of energy-efficient distributed algorithms and competitive centralized heuristics to select a connected correlation-dominating set of small size. The designed distributed algorithms can be implemented in an asynchronous communication model, and can tolerate message losses. We also design an exponential (but non-exhaustive) centralized approximation algorithm that returns a solution within O(log n) of the optimal size. Based on the approximation algorithm, we design a class of efficient centralized heuristics that are empirically shown to return near-optimal solutions. Simulation results over randomly generated sensor networks with both artificially and naturally generated data sets demonstrate the efficiency of the designed algorithms and the viability of our technique -- even in dynamic conditions.

Power balanced coverage-time optimization for clustered wireless sensor networks

Abstract: We consider a wireless sensor network in which sensors are grouped into clusters, each with its own cluster head (CH). Each CH collects data from sensors in its cluster and relays them to a sink node directly or through other CHs. The coverage time of the network is defined as the time until one of the CHs runs out of battery, resulting in an incomplete coverage of the sensing region. We study the maximization of coverage time by balancing the power consumption of different CHs. Using a Rayleigh fading channel model for inter-cluster communications, we provide optimal power allocation strategies that guarantee (in a probabilistic sense) an upper bound on the end-to-end (inter-CH) path reliability. Our allocation strategies account for the interaction between routing and clustering by considering the impacts of intra- and inter-cluster traffic at each CH. Two mechanisms are proposed for achieving balanced power consumption: the routing-aware optimal cluster planning and the clustering-aware optimal random relay. For both mechanisms, the problem is formulated as a signomial optimization, which can be efficiently solved using generalized geometric programming. Numerical examples and simulations are used to validate our analysis and study the performance of the proposed schemes.

A unified energy-efficient topology for unicast and broadcast

Abstract: We propose a novel communication efficient topology control algorithm for each wireless node to select communication neighbors and adjust its transmission power, such that all nodes together self-form a topology that is energy efficient simultaneously for both unicast and broadcast communications. We prove that the proposed topology is planar, which guarantees packet delivery if a certain localized routing method is used; it is power efficient for unicast-- the energy needed to connect any pair of nodes is within a small constant factor of the minimum under a common power attenuation model; it is efficient for broadcast: the energy consumption for broadcasting data on top of it is asymptotically the best compared with structures constructed locally; it has a constant bounded logical degree, which will potentially reduce interference and signal contention. We further prove that the average physical degree of all nodes is bounded by a small constant. To the best of our knowledge, this is the first communication-efficient distributed algorithm to achieve all these properties. Previously, only a centralized algorithm was reported in [3]. Moreover, by assuming that the ID and position of every node can be represented in O(log n) bits for a wireless network of n nodes, our method uses at most 13n messages, where each message is of O(log n) bits. We also show that this structure can be efficiently updated for dynamical network environment. Our theoretical results are corroborated in the simulations.

COMMIT: a sender-centric truthful and energy-efficient routing protocol for ad hoc networks with selfish nodes

Abstract: We consider the problem of establishing a route and sending packets between a source/destination pair in ad hoc networks composed of rational selfish nodes, whose purpose is to maximize their own utility. In order to motivate nodes to follow the protocol specification, we use side payments that are made to the forwarding nodes. Our goal is to design a fully distributed algorithm such that: (i) a node is always better off participating in the protocol execution (individual rationality), (ii) a node is always better off behaving according to the protocol specification (truthfulness), (iii) messages are routed along the most energy-efficient path, and (iv) the message complexity is reasonably low. We introduce the COMMIT protocol for individually rational, truthful, and energy-efficient routing in ad-hoc networks. To the best of our knowledge, this is the first ad hoc routing protocol with these features. COMMIT is based on the VCG payment scheme, in conjunction with a novel game-theoretic technique to achieve truthfulness for the sender node. By means of simulation, we show that the inevitable economic inefficiency is small. As an aside, our work demonstrates the advantage of using a cross-layer approach to solving problems: leveraging the existence of an underlying topology control protocol, we are able to simplify the design and analysis of our routing protocol, and to reduce its message complexity. On the other hand, our investigation of the routing problem in presence of selfish nodes disclosed a new metric under which topology control protocols can be evaluated: the cost of cooperation.

Motion planning with wireless network constraints

Abstract: This work discusses feasibility aspects of motion planning for groups of agents connected by a range-constrained wireless network. Specifically, we address the difficulties encountered when trajectories are required to preserve the connectedness of the network. The analysis utilizes a quantity called the connectivity robustness of the network, which can be calculated in a distributed fashion, and thus is applicable to distributed motion planning problems arising in control of vehicle networks. Further, these results show that network constraints posed as connectivity robustness constraints have minimal impact on reachability, provided that an appropriate topology control algorithm is implemented. This contrasts with more naive approaches to connectivity maintenance, which can significantly reduce the reachable set.

Minimum power configuration in wireless sensor networks

Abstract: This paper proposes the minimum power configuration (MPC) approach to energy conservation in wireless sensor networks. In sharp contrast to earlier research that treats topology control, power-aware routing, and sleep management in isolation, MPC integrates them as a joint optimization problem in which the power configuration of a network consists of a set of active nodes and the transmission powers of the nodes. We show through analysis that the minimum power configuration of a network is inherently dependent on the data rates of sources. We propose several approximation algorithms with provable performance bounds compared to the optimal solution, and a practical Minimum Power Configuration Protocol (MPCP) that can dynamically (re)configure a network to minimize the energy consumption based on current data rates. Simulations based on realistic radio models of the Mica2 motes show that MPCP can conserve significantly more energy than existing minimum power routing and topology control protocols.

Reducing interference in ad hoc networks through topology control

Abstract: Topology control aims to increase the lifetime of an ad hoc network by selecting only a subset of the available links to be used for routing. The tradeoff between keeping the spanner properties of the graph while sparsifying the graph has been well studied. However, it has often been assumed that a sparse graph implicitly has low interference, but recent research shows that that is not necessarily true. In this paper, we discuss different methods to measure interference, and present a new interference model that aims to describe the interference of the entire network, rather than just the worst part of it.We present API, a topology control algorithm that serves two purposes: it minimizes the interference in the network according to our metrics, and it keeps the spanner properties of the original graph. The paper is completed by simulations that compare different topologies with respect to different interference metrics.

Simulating Large Wireless Sensor Networks Using Cellular Automata

Abstract: A wireless sensor network is a special kind of ad hoc network where the nodes can sense, actuate, compute and communicate with each other using point-to-point multi-hop communication. Sensor networks can be used in a wide range of applications, such as environmental monitoring and industrial applications. Despite their potential applications, such networks have particular features imposed by resource restrictions, such as low computational power, reduced bandwidth and specially limited power source. Nowadays, real wireless sensor networks infrastructures are still very expensive. Therefore, most of the evaluations of new protocols are being made through simulation tools. The objective of this work is to verify the applicability of using cellular automata to simulate some aspects of sensor networks. A simulator has been developed to evaluate an algorithm for a very common problem in sensor networks: the topology control. The solution presented is based on the geographical position and the operational states of the sensor nodes. The obtained results indicate that cellular automata can be used with success to simulate large wireless sensor networks.

Autonomous reconfiguration in free-space optical sensor networks

Abstract: This research focuses on the physical and logical control and reconfigurability of network topologies through intelligent and dynamic rearrangement of nodes in an optical wireless sensor network. We address high data rate sensor networks (e.g., infrastructure monitoring; surveillance), which consist of gigabit per second, narrow beam, free-space optical links between fixed and/or mobile nodes. In our approach, the seamless operation of such networks requires maintenance of wireless link connectivity and quality and at all times, amidst, for example, changing atmospheric, and traffic and platform conditions. This is achieved by dynamic reconfiguration through topology control. We address the problem of dynamic formulation of topologies, which contain only two transceivers per communications node or switch. The task of reconfiguration requires the formation of a biconnected graph or a ring topology. The problem is similar to the traveling salesman problem and is NP complete. We address the mixed integer programming formulation of this problem, and show that it does not scale even for a small network. We then focus on heuristics for dynamic, autonomous reconfiguration. Using simulations, we investigate tradeoff between solution quality and computational time. We also investigate the effectiveness of these dynamic reconfiguration heuristics compared to fixed, degraded topologies.

Interference-aware routing in multihop wireless networks using directional antennas

Abstract: Recent research has shown that interference can make a significant impact on the performance of multihop wireless networks. Researchers have studied interference-aware topology control recently [M. Burkhart et al., 2004]. In this paper, we study routing problems in a multihop wireless network using directional antennas with dynamic traffic. We present new definitions of link and path interference that are suitable for designing better routing algorithms. We then formulate and optimally solve two power constrained minimum interference single path routing problems. Routing along paths found by our interference-aware algorithms tends to have less channel collisions and higher network throughput. Our simulation results show that, compared with the minimum power path routing algorithm, our algorithms can reduce average path interference by 40% or more at the cost of a minor power increase. We also extend our work towards survivable routing by formulating and solving the power constrained minimum interference node-disjoint path routing problem.

Localized algorithms for energy efficient topology in wireless ad hoc networks

Abstract: Topology control in wireless ad hoc networks is to select a subgraph of the communication graph (when all nodes use their maximum transmission range) with some properties for energy conservation. In this paper, we propose two novel localized topology control methods for homogeneous wireless ad hoc networks.Our first method constructs a structure with the following attractive properties: power efficient, bounded node degree, and planar. Its power stretch factor is at most ρ=1/1-(2sin π/k)β, and each node only has to maintain at most k + 5 neighbors where the integer k > 6 is an adjustable parameter, and β is a real constant between 2 and 5 depending on the wireless transmission environment. It can be constructed and maintained locally and dynamically. Moreover, by assuming that the node ID and its position can be represented in O(log n) bits each for a wireless network of n nodes, we show that the structure can be constructed using at most 24n messages, where each message is O(log n) bits.Our second method improves the degree bound to k, relaxes the theoretical power spanning ratio to ρ = √2β/1-(2√2sin π/k)β, where k > 8 is an adjustable parameter, and keeps all other properties. We show that the second structure can be constructed using at most 3n messages, where each message has size of O (log n) bits.We also experimentally evaluate the performance of these new energy efficient network topologies. The theoretical results are corroborated by the simulations: these structures are more efficient in practice, compared with other known structures used in wireless ad hoc networks and are easier to construct. In addition, the power assignment based on our new structures shows low energy cost and small interference at each wireless node.

Broadcasting and Topology Control in Wireless Ad Hoc Networks.

Abstract: Network wide broadcasting in Mobile Ad Hoc Networks (MANET) provides important control and route establishment functionality for a number of unicast and multicast protocols. We present an overview of the recent progress of broadcasting and multicasting in wireless ad hoc networks. We discuss two energy models that could be used for broadcast: one is non-adjustable power and one is adjustable power. If the power consumed at each node is not adjustable, minimizing the total power used by a reliable broadcast tree is equivalent to the minimum connected dominating set problem (MCDS), i.e., minimize the number of nodes that relay the message, since all relaying nodes of a reliable broadcast form a connected dominating set (CDS). If the power consumed at each node is adjustable, we assume that the power consumed by a relay node u is ‖uv‖ , where real number β ∈ [2, 5] depends on transmission environment and v is the farthest neighbor of u in the broadcast tree. For both models, we reviewed several centralized methods that compute broadcast trees consuming the energy within a constant factor of the optimum if the original communication graph is unit disk graph. Since centralized methods are expensive to implement, We further reviewed several localized methods that can approximate the minimum energy broadcast tree for non-adjustable power case. For adjustable power case, no localized methods can approximate the minimum energy broadcast tree and thus review several currently best possible heuristics. Several local improvement methods and activity scheduling of nodes (active, idle, sleep) are also

Interference arises at the receiver

Abstract: Energy consumption in general and interference in particular being among the most critical issues in wireless networks, this paper introduces an explicit definition of interference, based on the number of other nodes by which a given network node can be disturbed. With this definition we show that there exist instances of sensor networks in which no topology control algorithm - aiming at interference reduction by having nodes restrict their transmission power levels - can construct a valid data gathering network with interference less than logarithmic in the number of network nodes n. In a second part of the paper we introduce the nearest component connector (NCC) algorithm, which asymptotically matches this lower bound, guaranteeing to build a valid topology with interference in O(log n) in any given sensor network. Finally the paper compares NCC to other previously proposed data gathering structures in average-case networks.

Efficient topology control for ad-hoc wireless networks with non-uniform transmission ranges

Abstract: Wireless network topology control has drawn considerable attention recently. Priori arts assumed that the wireless ad hoc networks are modeled by unit disk graphs (UDG), i.e., two mobile hosts can communicate as long as their Euclidean distance is no more than a threshold. However, practically, the networks are never so perfect as unit disk graphs: the transmission ranges may vary due to various reasons such as the device differences, the network control necessity, and the perturbation of the transmission ranges even the transmission ranges are set as the same originally. Thus, we assume that each mobile host has its own transmission range. The networks are modeled by mutual inclusion graphs (MG), where two nodes are connected iff they are within the transmission range of each other. Previously, no method is known for topology control when the networks are modeled as mutual inclusion graphs.The paper proposes the first distributed mechanism to build a sparse power efficient network topology for ad hoc wireless networks with non-uniform transmission ranges. We first extend the Yao structure to build a spanner with a constant length and power stretch factor for mutual inclusion graph. We then propose two efficient localized algorithms to construct connected sparse network topologies. The first structure, called extended Yao-Yao, has node degree at most O(log γ), where γ = maxu maxuv∈MG ru/rv. The second structure, called extended Yao and Sink, has node degree bounded by O(log γ), and is a length and power spanner. The methods are based on a novel partition strategy of the space surrounded each mobile host. Both algorithms have communication cost O(n) under a local broadcasting communication model, where each message has O(log n) bits.

Scalable topology control for deployment-support networks

Abstract: Deployment-support networks (DSNs) have been proposed as a novel tool for the development, test, deployment, and validation of wireless sensor networks. They are expected to enhance scalability and flexibility in deployment by eliminating cable connections. In this paper, we describe our implementation of a DSN, giving details on the algorithms for topology control and maintenance. We provide various measurements of DSNs spanning up to 71 BTnode rev3 devices, featuring the largest Bluetooth scatternet reported to date. We also discuss our experience gained in the development and experimentation. Our results strongly suggest that our implementation scales well to a large number of nodes.

Monotone percolation and the topology control of wireless networks

Abstract: This paper addresses the topology control problem for large wireless networks that are modelled by an infinite point process on a two-dimensional plane. Topology control is the process of determining the edges in the network by adjusting the transmission radii of the nodes. Topology control algorithms should be based on local decisions, be adaptive to changes, guarantee full connectivity and support efficient routing. We present a family of topology control algorithms that, respectively, achieve some or all of these requirements efficiently. The key idea in our algorithms is a concept that we call monotone percolation. In classical percolation theory, we are interested in the emergence of an infinitely large connected component. In contrast, in monotone percolation we are interested in the existence of a relatively short path that makes monotonic progress between any pair of source and destination nodes. Our key contribution is that we demonstrate how local decisions on the transmission radii can lead to monotone percolation and in turn to efficient topology control algorithms.

Low-energy localized clustering: an adaptive cluster radius configuration scheme for topology control in wireless sensor networks

Abstract: This paper addresses an adaptive and dynamic localized scheme unique to hierarchical clustering protocols in wireless sensor networks, while reducing the consumption of residual energy of cluster heads and as a result delivering a prolonged sensor network lifetime. Our proposed scheme, low-energy localized clustering (LLC) aims to minimize energy consumption of cluster heads while the entire sensor network is still being covered. For achieving this goal, LLC dynamically regulates the radius of each cluster. Through a simulation based performance of this algorithm, LLC, we show that our novel cluster radius configuration algorithm achieves the desirable properties.