Computer Engineering / Bilgisayar Mühendisliği
Permanent URI for this collectionhttps://hdl.handle.net/11147/10
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Conference Object Citation - WoS: 37Graph Theoretic Clustering Algorithms in Mobile Ad Hoc Networks and Wireless Sensor Networks (survey)(Azerbaijan National Academy of Sciences, 2007) Erciyeş, Kayhan; Dağdeviren, Orhan; Çokuslu, Deniz; Özsoyeller, DenizClustering in mobile ad hoc networks (MANETs) and wireless sensor networks (WSNs) is an important method to ease topology management and routing in such networks. Once the clusters are formed, the leaders (coordinators) of the clusters may be used to form a backbone for efficient routing and communication purposes. A set of clusters may also provide the underlying physical structure for multicast communication for a higher level group communication module which may effectively be used for fault tolerance and key management for security purposes. We survey graph theoretic approaches for clustering in MANETs and WSNS and show that although there is a wide range of such algorithms, each may be suitable for a different cross-layer design objective.Conference Object Duyarga Ağları için Bir Γ Eşuyumcusu Tasarım ve Uygulaması(IEEE, 2008) Özsoyeller, Deniz; Erciyeş, Kayhan; Dağdeviren, OrhanImplementation of synchronous algorithms in distributed systems in general is less troublesome than the implementation of asynchronous algorithms. Synchronizers provide synchronous execution of an asynchronous algorithm in distributed systems. In this study, we propose a gamma synchronizer for Wireless Sensor Networks (WSNs). This synchronizer consists of a and beta synchronizers. In our work, the WSN is first divided into clusters and then these clusters are connected using a ring protocol. Synchronization is provided using the beta synchronizer in the cluster and a synchronizer among the clusters. We describe the clustering algorithm and the ring formation algorithm for the WSNs and give the results obtained so far.Conference Object Citation - Scopus: 2Telsiz Duyarga Ağlarında Hızlı Hareket Eden Hedefler için Küme Tabanlı Hedef İzleme Algoritması(Institute of Electrical and Electronics Engineers Inc., 2009) Alaybeyoğlu, Ayşegül; Dağdeviren, Orhan; Kantarcı, Aylin; Erciyes, KayhanKablosuz iletişim teknolojilerindeki ilerlemelerle birlikte telsiz duyarga ağları (TDA) birçok sivil ve askeri uygulamalarda özellikle de hareketli hedefin takibi gibi konularda yaygın olarak kullanılmaya başlanmıştır. Bu çalışmada da TDA’da hızlı hareket eden nesneler için küme tabanlı bir hedef izleme algoritması önerilmiştir. Literatürde bulunan mevcut çalışmalarda lider düğüm, hedefin sadece t+1 anında yaklaşacağı konumu tahminleyerek bu konuma en yakın düğümü uyandırır. Hedefin çok hızlı hareket etmesi durumunda ise hedefin kısa süre içerisinde bir grup düğümün yakınlarından algılanmadan geçip gitmesi söz konusudur. Önermiş olduğumuz algoritma ile hedefin hızına bağlı olarak, hedefin tahmini gideceği yöndeki düğümler önceden uyandırılarak, kümeler önceden oluşturulmaktadır. Böylece hedefin ani hızlanması durumunda, önceden oluşturmuş olduğumuz kümeler sayesinde hedefin kaybolma riskini azaltmış bulunmaktayız.Article Citation - WoS: 15Citation - Scopus: 21Tracking Fast Moving Targets in Wireless Sensor Networks(Institution of Electronics and Telecommunication Engineers, 2010) Alaybeyoğlu, Ayşegül; Erciyeş, Kayhan; Kantarcı, Aylin; Dağdeviren, OrhanWe propose a dynamic distributed algorithm for tracking objects that move fast in a sensor network. In the earlier efforts in tracking moving targets, the current leader node at time t predicts the location only for time t + 1 and if the target moves in high speed, it can pass by a group of nodes very fast without being detected. Therefore, as the target increases its speed, the probability of missing that target also increases. In this study, we propose a target tracking system that predicts future k locations of the target and awakens the -corresponding leader nodes so that the nodes along the trajectory self organize to form the clusters to collect data related to the target in advance and thus reduce the target misses. The algorithm first -provides detection of the target and forms a cluster with the neighboring nodes around it. After the selection of the cluster leader, the coordinates of the target is estimated using localization methods and cooperation -between the cluster nodes under the control of the leader node. The coordinates and the speed of the target are then used to estimate its trajectory. This information in turn provides the location of the nodes along the estimated trajectory which can be awaken, hence providing tracking of the moving object. We describe the algorithm, analyze its efficiency and show by simulations that it performs well to track very fast moving objects with speeds much higher than reported in literature.Conference Object Citation - Scopus: 5A Distributed Wakening Based Target Tracking Protocol for Wireless Sensor Networks(Institute of Electrical and Electronics Engineers Inc., 2010) Alaybeyoğlu, Ayşegül; Dağdeviren, Orhan; Kantarcı, Aylin; Erciyeş, KayhanWe propose a two layer protocol for tracking fast targets in sensor networks. At the lower layer, the Distributed Spanning Tree Algorithm (DSTA) [12] partitions the network into clusters with controllable diameter and constructs a spanning tree backbone of clusterheads rooted at the sink. At the upper layer, we propose a target tracking algorithm which wakes clusters of nodes by using the estimated trajectory beforehand, which is different from existing studies [3] in which target can be detected only when the nodes close to the target are awake. We provide the simulation results and show the effect of fore-waking operation by comparing error and miss ratios of existing approaches with our proposed target tracking algorithm. © 2010 IEEE.Article Citation - WoS: 13Citation - Scopus: 18Graph Matching-Based Distributed Clustering and Backbone Formation Algorithms for Sensor Networks(Oxford University Press, 2010) Dağdeviren, Orhan; Erciyeş, KayhanClustering is a widely used technique to manage the essential operations such as routing and data aggregation in wireless sensor networks (WSNs). We propose two new graph-theoretic distributed clustering algorithms for WSNs that use a weighted matching method for selecting strong links. To the best of our knowledge, our algorithms are the first attempts that use graph matching for clustering. The first algorithm is divided into rounds; extended weighted matching operation is executed by nodes in each round; thus the clusters are constructed synchronously. The second algorithm is the enhanced version of the first algorithm, which provides not only clustering but also backbone formation in an energy-efficient and asynchronous manner. We show the operation of the algorithms, analyze them, provide the simulation results in an ns2 environment. We compare our proposed algorithms with the other graph-theoretic clustering algorithms and show that our algorithms select strong communication links and create a controllable number of balanced clusters while providing low-energy consumptions. We also discuss possible applications that may use the structure provided by these algorithms and the extensions to the algorithms. © The Author 2009. Published by Oxford University Press on behalf of The British Computer Society. All rights reserved.Conference Object Citation - WoS: 13Citation - Scopus: 14Performance Evaluation of Cluster-Based Target Tracking Protocols for Wireless Sensor Networks(Institute of Electrical and Electronics Engineers Inc., 2009) Alaybeyoğlu, Ayşegül; Dağdeviren, Orhan; Erciyeş, Kayhan; Kantarcı, AylinTarget tracking is an important application type for wireless sensor networks (WSN). Recently, various approaches [1-11] are proposed to maintain the accurate tracking of the targets as well as low energy consumption. Clustering is a fundamental technique to manage the scarce network resources [12-19]. The message complexity of an application can be significantly decreased when it is redesigned on top of a clustered network. Clustering has provided an efficient infrastructure in many existing studies [1-8]. The clusters can be constructed before the target enters the region which is called the static method [1-4] or clusters are created by using received signal strength (RSS) from target which is called the dynamic method [5-8]. In this paper we provide simulations of static and dynamic clustering algorithms against various mobility models and target speeds. The mobility models that we applied are Random Waypoint Model, Random Direct Model and Gauss Markov Model. We provide metrics to measure the tracking performance of both approaches. We show that the dynamic clustering is favorable in terms of tracking accuracy whereas the energy consumption of static clustering is significantly smaller. We also show that the target moving with Gauss Markov Model can be tracked more accurately than the other models.Conference Object Citation - WoS: 12Citation - Scopus: 20A Hierarchical Leader Election Protocol for Mobile Ad Hoc Networks(Springer Verlag, 2008) Dağdeviren, Orhan; Erciyeş, KayhanLeader Election is an important problem in mobile ad hoc networks and in distributed computing systems. In this study, we propose a hierarchical, cluster based protocol to elect a leader in a mobile ad hoc network. The initial phase of the protocol employs a clustering algorithm to group nodes of the network after which a leader for a cluster(clusterhead) is elected. The second phase is performed by forming a connected ring of these leaders using the Ring Formation Algorithm. Finally, Chang Roberts Leader Election Algorithm for rings is employed in the final phase to elect the super-leader among the clusterheads. We provide performance results of this protocol for various mobility parameters and analyze its time and message complexities.Conference Object Citation - WoS: 13Citation - Scopus: 12Distributed Algorithms To Form Cluster Based Spanning Trees in Wireless Sensor Networks(Springer Verlag, 2008) Erciyeş, Kayhan; Özsoyeller, Deniz; Dağdeviren, OrhanWe propose two algorithms to form spanning trees in sensor networks. The first algorithm forms hierarchical clusters of spanning trees with a given root, the sink. All of the nodes in the sensor network are then classified iteratively as subroot, intermediate or leaf nodes. At the end of this phase, the local spanning trees are formed, each having a unique subroot (clusterhead) node. The communication and data aggregation towards the sink by an ordinary node then is accomplished by sending data to the local subroot which routes data towards the sink. A modified version of the first algorithm is also provided which ensures that the obtained tree is a breadth-first search tree where a node can modify its parent to yield shorter distances to the root. Once the sub-spanning trees in the clusters are formed, a communication architecture such as a ring can be formed among the subroots. This hybrid architecture which provides co-existing spanning trees within clusters yields the necessary foundation for a two-level communication protocol in a sensor network as well as providing a structure for a higher level abstraction such as the γ synchronizer where communication between the clusters is performed using the ring similar to an α synchronizer and the intra cluster communication is accomplished using the sub-spanning trees as in the β synchronizers. We discuss the model along with the algorithms, compare them and comment on their performances.Conference Object Citation - Scopus: 38On the Ieee 802.15.4 Mac Layer Attacks: Gts Attack(Institute of Electrical and Electronics Engineers Inc., 2008) Sokullu, Radosveta; Dağdeviren, Orhan; Korkmaz, İlkerIn the last several years IEEE 802.15.4 [1] has been accepted as a major MAC layer protocol for wireless sensor networks (WSNs) and has attracted the interest of the research community involved in security issues as the increased range of application scenarios bring out new possibilities for misuse and taking improper advantage of sensor nodes and their operation. As these nodes are very resource restrained such possible attacks and their early detection must be carefully considered. This paper surveys the known attacks on wireless sensor networks, identifies and investigates a new attack, Guaranteed Time Slot (GTS) attack, taking as a basis the IEEE 802.15.4 MAC protocol for WSN. The GTS Attack is simulated with different scenarios using ns-2 and the results are evaluated both from the point of view of the attacked and the attacker.