Topology Maintenance Research Articles

A Dead-End Free Topology Maintenance Protocol for Geographic Forwarding in Wireless Sensor Networks

Minimizing energy consumption is a fundamental requirement when deploying wireless sensor networks. Accordingly, various topology control protocols have been proposed, which aim to conserve energy by turning off unnecessary sensors while simultaneously preserving a constant level of routing fidelity. However, although these protocols can generally be integrated with any routing scheme, few of them take specific account of the issues which arise when they are integrated with geographic routing mechanisms. Of these issues, the dead-end situation is a particular concern. The dead-end phenomenon (also known as the "local maximum” problem) poses major difficulties when performing geographic forwarding in wireless sensor networks since whenever a packet encounters a dead end, additional overheads must be paid to forward the packet to the destination via an alternative route. This paper presents a distributed dead-end free topology maintenance protocol, designated as DFTM, for the construction of dead-end free networks using a minimum number of active nodes. The performance of DFTM is compared with that of the conventional topology maintenance schemes GAF and Span, in a series of numerical simulations conducted using the ns2 simulator. The evaluation results reveal that DFTM significantly reduced the number of active nodes required in the network and thus prolonged the overall network lifetime. DFTM also successfully constructed a dead-end free topology in most of the simulated scenarios. Additionally, even when the locations of the sensors were not precisely known, DFTM still ensured that no more than a very few dead-end events occurred during packet forwarding.

The minimum positional error incurred by any connectivity-based positioning algorithm for mobile wireless systems

A very important problem in many wireless ad-hoc networks, including wireless sensor networks, is positioning or the determination of geographical locations of the wireless nodes. Positioning is used both in infrastructural aspects of sensor networks, like geographic routing and topology maintenance, and in applications like wildlife tracking. Connectivity-based positioning algorithms in mobile wireless systems are studied in this work. These algorithms compute node positions based only on the connectivity, i.e. the neighborhood information of each node. Many algorithms have been proposed for positioning in stationary node systems and bounds on positional error of algorithms have been derived. The design and analysis of positioning algorithms for mobile node systems is a more challenging problem. Node mobility increases the amount of positional information available to a positioning algorithm. The work in this paper establishes a bound on the positional error for connectivity-based algorithms in mobile systems. The formulation from the analysis is used to investigate the benefit of this additional positional information on reducing positional error. There is a limit to the usefulness of positional information from previous node positions due to movement. This captures an important performance tradeoff: historical positional information can yield reduced positional error but requires more connectivity information from the network which requires greater computational resources.

Research on the Access Method of Distributed Control Channel in WMN Based on TDMA

The access strategy and method of control channel in WMN is an important research project. In this paper, description of access strategy and the method on distributed control channel in WMN based on TDMA are carried out, the coordination mechanism of multiple channels and allocation algorithm of controlling time slot to make the access of control channel fast and fair are proposed. Finally, the paper formulates protocol specification of control channel access, being appropriate for large-scale network, and discusses its application in the maintenance of network topology, route discovery and the establishment of QoS request.

Securing Topology Maintenance Protocols for Sensor Networks

We analyze the security vulnerabilities of PEAS, ASCENT, and CCP, three well-known topology maintenance protocols (TMPs) for sensor networks. These protocols aim to increase the lifetime of the sensor network by only maintaining a subset of nodes in an active or awake state. The design of these protocols assumes that the sensor nodes will be deployed in a trusted, nonadversarial environment, and does not take into account the impact of attacks launched by malicious insider or outsider nodes. We propose a metaprotocol (Meta-TMP) to represent the class of topology maintenance protocols. The Meta-TMP provides us with a better understanding of the characteristics and of how a specific TMP works, and it can be used to study the vulnerabilities of a specific TMP. We describe various types of malicious behavior and actions that can be carried out by an adversary to attack a wireless sensor network by exploiting the TMP being used in the network. We describe three attacks against these protocols that may be used to reduce the lifetime of the sensor network, or to degrade the functionality of the sensor application by reducing the network connectivity and the sensing coverage that can be achieved. Further, we describe countermeasures that can be taken to increase the robustness of the protocols and make them resilient to such attacks.

A Scalable Heuristic Based on Hypercube Graph for Automated Planner

There are much research into Artificial Intelligence (AI) and Semantic Web over the past few years and intelligent behaviour such as learning, analysing, problem solving, planning and abstracting is displayed by modern computer systems. Automatically acquiring domain-knowledge for planning, as it is the case for Machine Learning in general, strongly depends on the training material. In planning, there is a novel ways to search knowledge when solving problems. This Paper presents a new heuristic for carrying out searches of training material, where metadata and the knowledge build into them are captured and fully scalable. These insfrastructure use AI Planning and Ontology technologies, allowing to construct learning rules dynamically based on the general Domain independent Planner even from disjoint learning objects, and meeting the learner’s profile, preferences needs and abilitity. We provide an efficient topology construction and maintenance algorithm, and show how our scheme can be made even more efficient by using a globally known ontology to determine the organization of nodes in the graph topology, allowing for efficient concept-based search.

ECS: Efficient Communication Scheduling for Underwater Sensor Networks

TDMA protocols have attracted a lot of attention for underwater acoustic sensor networks (UWSNs), because of the unique characteristics of acoustic signal propagation such as great energy consumption in transmission, long propagation delay and long communication range. Previous TDMA protocols all allocated transmission time to nodes based on discrete time slots. This paper proposes an efficient continuous time scheduling TDMA protocol (ECS) for UWSNs, including the continuous time based and sender oriented conflict analysis model, the transmission moment allocation algorithm and the distributed topology maintenance algorithm. Simulation results confirm that ECS improves network throughput by 20% on average, compared to existing MAC protocols.

Secure topology maintenance and events collection in WSNs

AbstractTopology Maintenance Protocols (TMPs) are key for operating Wireless Sensor Networks (WSNs). Their adoption serves a few goals, such as, to save energy, to avoid collisions in communications and to have an adequate number of nodes monitoring the environment—by alternating duty cycles with sleep cycles on the sensor nodes. While effectiveness of TMPs protocols is widely addressed, security is an overlooked feature. Indeed, while different TMPs have been presented in the literature, few of them address the security issues. In particular, only recently a secure TMP protocol that does not require pair‐wise node confidentiality has been proposed: Sec‐TMP. The aim of Sec‐TMP is to enforce event delivery to the Base Station while providing a standard topology maintenance service to the WSN. In this paper, we provide a thorough assessment of our previous preliminary proposal of Sec‐TMP, with particular reference to its effectiveness and security. First, we investigate the energy consumption introduced by TMPs protocols. Second, we show that Sec‐TMP performs well without any assumption neither on the show‐up time of data‐collecting node, nor on their mobility model. In particular, we test Sec‐TMP against a realistic unpredictable data‐collecting mobility scenario, that also brings in new security issues. A thorough security analysis of the proposed solutions to these new issues is also provided. Finally, extensive simulations support the quality of Sec‐TMP as for effectiveness and security. Copyright © 2011 John Wiley & Sons, Ltd.

Building 3D cadastral system based on 2D survey plans with SketchUp

Three-dimensional (3D) land development and utilization has become the trend for urban planning in the current metropolis. This paper presents a method for building a 3D cadastral management system from survey plans with SketchUp. It concentrates on the geometric representation and topological consistent maintenance of 3D cadastral objects. In this system a complete topological model is built to express the body construction and spatial relationships among 3D property units. SketchUp is used to automatically construct 3D models with attributes and thematic information from 2D survey plans. Spatial topologic relationships and operations are analyzed with the programming and development of Ruby language. The resulting system can manage 3D cadastral objects and manipulate them with spatial operations to support spatial analysis.

A Scalable Routing Architecture for Resource Discovery in Cloud Computing

Cloud Computing technology enables the sharing and collaborating of wide variety of resources. To fully utilize these resources, effective discovery techniques are necessities. Proposing and designing a resource discovery scheme based on Economic Agent. Base on the economic model and the technique in agent of grouping nodes sharing similar files to improve efficiency, this thesis suggests a resource discovery scheme based on economic agent, which is called EAGRD. Theoretical models on resource discovery are provided, under which EAGRD is compared with existing schemes theoretically. By controlling propagation of message into related communities, EAGRD improves time and network efficiency at the cost of topological maintenance overhead. Results from simulation demonstrate that this architecture is very effective in Cloud Computing resource discovery.

Resource Allocation for Parallel Task in Grids

Task running in Grids may require multiple types of resources simultaneously. Proposing and designing a resource discovery scheme based on Economic Agent. Base on the economic model and the technique in agent of grouping nodes sharing similar files to improve efficiency, this thesis suggests a resource discovery scheme based on economic agent, which is called EAGRD. Theoretical models on resource discovery are provided, under which EAGRD is compared with existing schemes theoretically. By controlling propagation of message into related communities, EAGRD improves time and network efficiency at the cost of topological maintenance overhead.

Realizing and benchmarking broadcast algorithms in wireless mesh networks

Broadcasting by flooding causes the broadcast storm problem in multi-hop wireless networks. This problem becomes more likely in a wireless mesh network (WMN) because WMNs can bridge wired LANs, increasing broadcast traffic and collision probability. Since the network control, routing, and topology maintenance of a WMN highly rely on layer-2 broadcasting, unreliable broadcast algorithms directly destabilize a WMN. Researchers have developed many algorithms for efficient and reliable broadcast in multi-hop wireless networks. However, real-world systems rarely verify or compare these approaches, especially in a WMN. This paper examines six representative broadcast algorithms: simple flooding, dynamic probabilistic, efficient counter-based broadcast, scalable broadcast, domain pruning, and connected-dominating-set based algorithms. This study addresses both common and algorithm-specific implementation in a real-world IEEE 802.11s WMN testbed. Experiments under various topologies and packet lengths reveal the reliability, forwarding ratio, and efficiency of these six algorithms. Quantitative survey results indicate that the scalable broadcast algorithm possesses the best reliability due to its lower collision probability. The domain-pruning algorithm is the most efficient algorithm when considering both reliability and the forwarding ratio.

Vibrio cholerae ParE2 Poisons DNA Gyrase via a Mechanism Distinct from Other Gyrase Inhibitors

DNA gyrase is an essential bacterial enzyme required for the maintenance of chromosomal DNA topology. This enzyme is the target of several protein toxins encoded in toxin-antitoxin (TA) loci as well as of man-made antibiotics such as quinolones. The genome of Vibrio cholerae, the cause of cholera, contains three putative TA loci that exhibit modest similarity to the RK2 plasmid-borne parDE TA locus, which is thought to target gyrase although its mechanism of action is uncharacterized. Here we investigated the V. cholerae parDE2 locus. We found that this locus encodes a functional proteic TA pair that is active in Escherichia coli as well as V. cholerae. ParD2 co-purified with ParE2 and interacted with it directly. Unlike many other antitoxins, ParD2 could prevent but not reverse ParE2 toxicity. ParE2, like the unrelated F-encoded toxin CcdB and quinolones, targeted the GyrA subunit and stalled the DNA-gyrase cleavage complex. However, in contrast to other gyrase poisons, ParE2 toxicity required ATP, and it interfered with gyrase-dependent DNA supercoiling but not DNA relaxation. ParE2 did not bind GyrA fragments bound by CcdB and quinolones, and a set of strains resistant to a variety of known gyrase inhibitors all exhibited sensitivity to ParE2. Together, our findings suggest that ParE2 and presumably its many plasmid- and chromosome-encoded homologues inhibit gyrase in a different manner than previously described agents.

Energy Efficient Multicast Routing Protocol for MANET with Minimum Control Overhead (EEMPMO)

Mobile Ad-Hoc Network (MANET) is a dynamic, multi-hop and autonomous network composed of light wireless mobile nodes. Multicast has great importance in MANET due to their inherent broadcast capability. However, due to the dynamic topology of MANETs to build optimal multicast trees and maintaining group membership a lot many control messages required. These overhead consume the mobile node resources like power and network resources like wireless links bandwidth that creates hurdle in implementing energy assurance and reduced overhead multicast protocol for Mobile Ad hoc Networks (MANET). This paper presents an energy efficient multicast routing protocol for MANET with minimum control overhead. The protocol creates shared multicast tree using the physical location of the nodes for the multicast sessions. Protocol employs a distributed location service to obtain the physical location information of the nodes, which effectively reduces the overheads for route searching and shared multicast tree maintenance. The algorithm uses the concept of small overlapped zones around each node for proactive topology maintenance with in the zone. To search for an existing multicast tree outside the zone, constrained directional forwarding is used which guarantees a good reduction in overhead in comparison to network wide flooding for search process. In this paper local connectivity technique and preventive route reconfiguration on the basis of the current status of the nodes are being proposed that attempts to improve the performance and reliability in terms of reduced overhead, power and bandwidth requirement. These techniques also ensure good reduction in latency in case of link breakages and prevention of the network from splitting. General Terms

SKIP: an efficient search mechanism in unstructured P2P networks

Search efficiency and accuracy of resource are important considerations for search algorithm in peer-to-peer (P2P) network. Most search algorithms use flooding among neighbor nodes to search relevant resource. However, this usually causes great amount of redundant messages, which results in high search costs and low search precision. In this paper, we use vector space model (VSM) and relevance ranking algorithms to construct overlay network, and a novel search mechanism search with K-iteration preference (SKIP) based on semantic group for P2P networks is proposed to efficiently solve these problems. The key idea of SKIP is to reorder the semantic neighbors of nodes according to relevant scores and to utilize preference selection during the process of query. We analysis and implement the scheme and reveal that the SKIP provides a low overhead on topology maintenance, which can be effectively used in P2P searching and verify it outperformance in higher precision and lower search cost by comparing with current semantic-based searching mechanism gnutella-like efficient searching system (GES).

Topology Maintenance: Extending the Lifetime of Wireless Sensor Networks

Topology Maintenance is the part of Topology Control dedicated to the periodical restoration of the network topology, in order to guarantee characteristics like connectivity and coverage. This article presents one of the first efforts to formalize this concept by presenting a taxonomy for different strategies to perform topology maintenance in wireless sensor networks, including static, dynamic and hybrid techniques, with global and local scope, and using different triggering criteria. In addition, a comparison is included to evaluate, in sparse and dense networks, the performance of global static, dynamic and hybrid techniques, with triggering criteria based on time and energy, and working jointly with the two well-known topology construction protocols A3 and CDS-Rule-K. The results show that the dynamic techniques always produce benefits in terms of extending the network lifetime, while static and hybrid techniques produce mixed results (worst and best), depending mainly on the nature of the construction protocols used.

Policy controlled self-configuration in unattended wireless sensor networks

With the decreasing cost and size of sensors, their importance has grown rapidly in the field of unattended network systems, which have a significant and vital role in military and security applications where human access is difficult once the nodes are deployed. A major issue in wireless sensor networks (WSN) is the limited availability of energy supply. The nodes have to cooperate and self-organize to provide an active backbone, making optimal use of energy by putting off the radio of the nodes which are not required. We propose the Policy Controlled Self-Configuration for Unattended Wireless Sensor Networks ( PCSSN) scheme for self-organization in WSN. The algorithm consists of two phases: topology discovery and topology maintenance. Based on the concepts of Markov Decision Processes (MDP) we design a policy to activate the optimum number of nodes such that the application fidelity is not affected. The policy is based on the distance between neighboring nodes, the residual energy, and the neighbor count, which are indicators of the hop count, the network lifetime, and the state of connectivity of the network, respectively. We also consider the case of node failures, since failures are quite common in harsh unattended environments. In this paper, we show that our proposed scheme increases the utility function ranging from about 7% to 50% as the number of nodes increases. Further, we show that despite the overhead involved in the proposed scheme, the energy spent is much less than the active case, in which all the nodes stay active forever, without going to sleep.

Maintaining the Ranch topology

Topology maintenance, or how to handle the possibly concurrent joining and leaving of nodes, is a central problem for structured peer-to-peer networks. A good topology maintenance protocol should run efficiently, fully maintain the topology, and should not unduly restrict concurrency. In this paper, we present such a protocol for a multi-ring topology called Ranch. The protocol is efficient: for each join or leave, it uses a logarithmic number of messages with high probability. The protocol fully maintains Ranch after joins and leaves, and allows for a high degree of concurrency. To our knowledge, this is the first maintenance protocol that enjoys all of these properties for a structured peer-to-peer network topology.

Second order centrality: Distributed assessment of nodes criticity in complex networks

A complex network can be modeled as a graph representing the “who knows who” relationship. In the context of graph theory for social networks, the notion of centrality is used to assess the relative importance of nodes in a given network topology. For example, in a network composed of large dense clusters connected through only a few links, the nodes involved in those links are particularly critical as far as the network survivability is concerned. This may also impact any application running on top of it. Such information can be exploited for various topological maintenance issues to prevent congestion and disruption. This can also be used offline to identify the most important actors in large social interaction graphs. Several forms of centrality have been proposed so far. Yet, they suffer from imperfections: initially designed for small social graphs, they are either of limited use (degree centrality), either incompatible in a distributed setting ( e.g. random walk betweenness centrality). In this paper we introduce a novel form of centrality: the second order centrality which can be computed in a distributed manner. This provides locally each node with a value reflecting its relative criticity and relies on a random walk visiting the network in an unbiased fashion. To this end, each node records the time elapsed between visits of that random walk (called return time in the sequel) and computes the standard deviation (or second order moment) of such return times. The key point is that central nodes see regularly the random walk compared to other topology nodes. Both through theoretical analysis and simulation, we show that the standard deviation can be used to accurately identify critical nodes as well as to globally characterize graphs topology in a distributed way. We finally compare our proposal to well-known centralities to assess its competitivity.

P2P Interactive Streaming System Based on Derivative Tree

This paper introduces a derivative tree-based P2P framework to support interactive streaming applications. The proposed scheme includes distributed discovery service for resource location and derivative tree-based caching structure for dissemination topology maintenance. By introducing the derivative tree into the system, the impact of dynamic node join/departure could be dramatically reduced. With the assistance of distributed hash table (DHT), the overhead of the resource searching, service reconstruction and overlay maintenance could be alleviated to an acceptable level. Extensive simulations show that the derived tree-based strategy performs well. The overhead of interactive operations in the scheme can be reduced by more than 50% compared to the existing P2P media streaming systems.

Energy Efficient Passive Clustering Based Directed Diffusion Protocol

In directed diffusion (DD), the diffusion of interest and exploratory data leads to heavy energy consumption. In this paper, we propose an improved directed diffusion routing protocol on the basis of Passive Clustering Directed Diffusion (PCDD). This protocol has many merits:1).In order to avoid the unbalance energy consumption, this protocol adopts cluster declaration mechanism based on energy threshold value and gateway selection mechanism based on residual energy.2).In order to reduce the energy consumption of the network topology reconfiguration， this protocol uses the cluster head or gateway re-election algorithm in network topology maintenance mechanism. Compared with the related works through simulation, the proposed protocol can improve the energy efficiency of the network. Besides, the protocol obtains a better performance of end to end delay. Moreover, it has higher average packet delivery ratio.