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 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: 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.Conference Object Citation - WoS: 7Citation - Scopus: 12Time Synchronization Algorithms Based on Timing-Sync Protocol in Wireless Sensor Networks(Institute of Electrical and Electronics Engineers Inc., 2008) Kulaklı, Ali Burak; Erciyeş, KayhanWireless Sensor Networks(WSN) are large scale networks of sensors running on wireless environment. For an application running on a WSN, gathered data by the sensors are time critical in most of the cases. However, almost all the nodes suffer from a problem named clock drift. This problem causes clock difference among nodes as time goes because the processors do not run exactly at the same speed. There are many proposed solutions to remedy this problem. TPSN (Timing-sync Protocol for Sensor Networks) is one of the effective protocols proposed to synchronize sensor networks. In this paper, we propose enhancements over TPSN to synchronize nodes in a wireless sensor network more effectively with a lower message complexity and higher precision.