Researcher:
Özkasap, Öznur

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Öznur

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Özkasap

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Researcher Of Publications: search.filters.isAuthorOfPublication.9b92fabc-2d3d-4057-a6d8-4fe3d5625c42

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Now showing 1 - 10 of 154
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    SecVLC: secure visible light communication for military vehicular networks
    (Association for Computing Machinery (ACM), 2016) Tsonev, Dobroslav; Burchardt, Harald; N/A; Department of Electrical and Electronics Engineering; Department of Computer Engineering; Uçar, Seyhan; Ergen, Sinem Çöleri; Özkasap, Öznur; PhD Student; Faculty Member; Faculty Member; Department of Electrical and Electronics Engineering; Department of Computer Engineering; Graduate School of Sciences and Engineering; College of Engineering; College of Engineering; N/A; 7211; 113507
    Technology coined as the vehicular ad hoc network (VANET) is harmonizing with Intelligent Transportation System (ITS) and Intelligent Traffic System (ITF). An application sce- nario of VANET is the military communication where ve- hicles move as a convoy on roadways, requiring secure and reliable communication. However, utilization of radio fre- quency (RF) communication in VANET limits its usage in military applications, due to the scarce frequency band and its vulnerability to security attacks. Visible Light Communi- cation (VLC) has been recently introduced as a more secure alternative, limiting the reception of neighboring nodes with its directional transmission. However, secure vehicular VLC that ensures confidential data transfer among the participat- ing vehicles, is an open problem. In this paper, we propose a secure military light communication protocol (SecVLC) for enabling efficient and secure data sharing. We use the directionality property of VLC to ensure that only target vehicles participate in the communication. Vehicles use full- duplex communication where infra-red (IR) is utilized to share a secret key and VLC is used to receive encrypted data. We experimentally demonstrate the suitability of SecVLC in outdoor scenarios at varying inter-vehicular distances with key metrics of interest, including the security, data packet delivery ratio and delay.
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    PPAD: privacy preserving group-based advertising in online social networks
    (IEEE, 2018) N/A; Department of Computer Engineering; Department of Computer Engineering; Boshrooyeh, Sanaz Taheri; Küpçü, Alptekin; Özkasap, Öznur; PhD Student; Faculty Member; Faculty Member; Department of Computer Engineering; Graduate School of Sciences and Engineering; College of Engineering; College of Engineering; N/A; 168060; 113507
    Services provided as free by Online Social Networks (OSN) come with privacy concerns. Users' information kept by OSN providers are vulnerable to the risk of being sold to the advertising firms. To protect user privacy, existing proposals utilize data encryption, which prevents the providers from monetizing users' information. Therefore, the providers would not be financially motivated to establish secure OSN designs based on users' data encryption. Addressing these problems, we propose the first Privacy Preserving Group-Based Advertising (PPAD) system that gives monetizing ability for the OSN providers. PPAD performs profile and advertisement matching without requiring the users or advertisers to be online, and is shown to be secure in the presence of honest but curious servers that are allowed to create fake users or advertisers. We also present advertisement accuracy metrics under various system parameters providing a range of security-accuracy trade-offs.
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    Dynamic QoS/QoE-aware reliable service composition framework for edge intelligence
    (Springer, 2022) Otoum, Safa; N/A; Department of Computer Engineering; Hayyolalam, Vahideh; Özkasap, Öznur; PhD Student; Faculty Member; Department of Computer Engineering; Graduate School of Sciences and Engineering; College of Engineering; N/A; 113507
    Edge intelligence has become popular recently since it brings smartness and copes with some shortcomings of conventional technologies such as cloud computing, Internet of Things (IoT), and centralized AI adoptions. However, although utilizing edge intelligence contributes to providing smart systems such as automated driving systems, smart cities, and connected healthcare systems, it is not free from limitations. There exist various challenges in integrating AI and edge computing, one of which is addressed in this paper. Our main focus is to handle the adoption of AI methods on resource-constrained edge devices. In this regard, we introduce the concept of Edge devices as a Service (EdaaS) and propose a quality of service (QoS) and quality of experience (QoE)-aware dynamic and reliable framework for AI subtasks composition. The proposed framework is evaluated utilizing three well-known meta-heuristics in terms of various metrics for a connected healthcare application scenario. The experimental results confirm the applicability of the proposed framework. Moreover, the results reveal that black widow optimization (BWO) can handle the issue more efficiently compared to particle swarm optimization (PSO) and simulated annealing (SA). The overall efficiency of BWO over PSO is 95%, and BWO outperforms SA with 100% efficiency. It means that BWO prevails SA and PSO in all and 95% of the experiments, respectively.
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    Peer-to-peer multipoint video conferencing with layered video
    (Academic Press Ltd-Elsevier Science Ltd, 2011) Akkuş, İstemi Ekin; Civanlar, Mehmet Reha; Department of Computer Engineering; Özkasap, Öznur; Faculty Member; Department of Computer Engineering; College of Engineering; 113507
    A peer-to-peer (P2P) architecture for multipoint video conferencing using layered video coding at the end hosts is proposed. The system primarily targets end points with low bandwidth network connections and enables them to create a multipoint video conference without any additional networking and computing resources beyond what is needed for a point-to-point conference. For P2P multipoint video conferencing applications, wide-area collaboration is significant for connecting participants from different parts around the globe to support collaborative work. In our system, peers collaborate for streaming video, and the motivation behind the use of layered video is to overcome the problem of denying video requests by peers and assure that each participant peer can view any other participant at any configuration. Layered video encoding techniques usable within this architecture are discussed. A protocol for operating the system has been developed, simulated and its performance has been analyzed. Furthermore, a multi-objective optimization approach has been developed to simultaneously minimize the number of base layer receivers and the delay experienced by the peers while maximizing the granted additional requests to support peers having multiple video input bandwidths. The use of the multi-objective optimization scheme is demonstrated through an example scenario and simulations. A prototype has also been implemented, and the system has been formally specified and verified.
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    Awake: decentralized and availability aware replication for P2P cloud storage
    (Ieee, 2016) N/A; N/A; Department of Computer Engineering; Department of Computer Engineering; Hassanzadeh-Nazarabadi, Yahya; Küpçü, Alptekin; Özkasap, Öznur; PhD Student; Faculty Member; Faculty Member; Department of Computer Engineering; Graduate School of Sciences and Engineering; College of Engineering; College of Engineering; N/A; 168060; 113507
    The traditional decentralized availability-based replication algorithms suffer from high dependence on the underlying system's churn behavior, randomness in replica selection, and the inability of maximizing the replicas availability. These drawbacks result in poor data availability especially in low available systems as well as where the churn behavior is mispredicted. In this paper, we propose dynamic, fully decentralized availability aware algorithm named Awake, with the goal of maximizing the availability of replicas. Compared to the existing solutions, Awake always provides the maximum availability of replicas regardless of the underlying system's churn behavior. By employing Awake, a data owner can select its replicas only based on the aggregated availability information of nodes obtained in a fully decentralized manner with asymptotically the same message overhead as the communication complexity of the underlying system. Awake has linear space complexity in the number of registered users to the system. Our extensive simulation results show that in comparison to the best existing decentralized solutions, regardless of the underlying churn model of the system, Awake improves the availability of replicas with a gain of about 21%. Likewise, Awake is scalable by showing the same performance independent of the system size.
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    Seed-based distributed group key selection algorithm for ad hoe networks
    (IEEE, 2007) N/A; Department of Computer Engineering; Atsan, Emre; Özkasap, Öznur; Master Student; Faculty Member; Department of Computer Engineering; Graduate School of Sciences and Engineering; College of Engineering; N/A; 113507
    Key establishment has a significant role in providing secure infrastructure for ad hoc networks. For this purpose, several key pre-distribution schemes have been proposed, but majority of the existing schemes rely on a trusted third party which causes a constraint in ad hoc platforms. We propose a seed-based distributed key selection algorithm, namely SeeDKS, for groups of nodes in ad hoc networks. Our approach is inspired by the earlier work on distributed key selection (DKS) and is based on the idea of common group key pool generated with group seed value for each different group. Simulation results show that using very small key ring sizes compared to DKS, we can achieve satisfactory results which DKS cannot accomplish in means of finding at least one common key among group members.
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    Green proxy-based approaches for BitTorrent
    (IEEE, 2014) Anastasi, Giuseppe; Department of Computer Engineering; Department of Computer Engineering; Cebeci, Sena Efsun; Özkasap, Öznur; Researcher; Faculty Member; Department of Computer Engineering; College of Engineering; College of Engineering; N/A; 113507
    Energy efficiency in P2P systems has become a prominent issue due to significant portions of the Internet traffic devoted to P2P protocols. In this paper, we address the approaches for energy efficiency in BitTorrent Protocol. First, we provide a classification of the existing energy efficient BitTorrent studies, and then propose multi-proxy and private proxy approaches to minimize energy consumption. We develop energy cost formulations for our proposed protocols as well as the legacy BitTorrent. The performance of multi-proxy and private proxy BitTorrent is analyzed through a comprehensive set of simulations performed on Peersim for the energy consumption and average download time metrics. For the multi-proxy protocol, we investigate the effect of increasing the number of proxies on the overlay. We also present preliminary experimental results on large-scale scenarios revealing that the proxy-based schemes reduce the energy consumption up to 80% without any performance degradation in comparison to the legacy BitTorrent.
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    Framework for traffic proportional energy efficiency in software defined networks
    (IEEE, 2018) N/A; Department of Computer Engineering; Assefa, Beakal Gizachew; Özkasap, Öznur; PhD Student; Faculty Member; Department of Computer Engineering; Graduate School of Sciences and Engineering; College of Engineering; N/A; 113507
    Software Defined Networking (SDN) achieves programmability of network elements by separating the control and the forwarding planes, and provides efficiency through optimized routing and flexibility in network management. As the energy costs contribute largely to the overall costs in networks, energy efficiency is a significant design requirement for modern networking mechanisms. However, designing energy efficient solutions is complicated since there is a trade-off between energy efficiency and network performance. In this paper, we propose traffic proportional energy efficient framework for SDN and heuristics algorithm that maintains the tradeoff between efficiency and performance. We also present IP formulation for traffic proportional energy efficiency problem. Comprehensive experiments conducted on Mininet emulator and PDX controller using Abilene, Atlanta, and Nobel-Germany real-world topologies and traffic traces show that our approach saves up to 50% energy while achieving a performance closer to the algorithms prioritizing performance.
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    LARAS: locality aware replication algorithm for the Skip Graph
    (Institute of Electrical and Electronics Engineers (IEEE), 2016) N/A; N/A; Department of Computer Engineering; Department of Computer Engineering; Hassanzadeh-Nazarabadi, Yahya; Küpçü, Alptekin; Özkasap, Öznur; PhD Student; Faculty Member; Faculty Member; Department of Computer Engineering; Graduate School of Sciences and Engineering; College of Engineering; College of Engineering; N/A; 168060; 113507
    Skip Graph, a member of the distributed hash table (DHT) family, has several benefits as an underlying structure in peer-to-peer (P2P) storage systems. In such systems, replication plays a key role on the system's performance. The traditional decentralized replication algorithms do not consider the locations of Skip Graph nodes in the network. Negligence of node locations in the placement of the replicas results in high access delays between the nodes and their closest replicas. This negatively affects the performance of the whole storage system. In this paper, with the aim of making Skip Graph's replication locality aware, we propose dynamic fully decentralized LARAS approach, where the data owner can replicate itself based on the system size, possible data requester nodes' set and using local information of the storage system. Our extensive performance results show that LARAS improves replication access delay of the Skip Graph based storage system about 20% and 38% in comparison to the best known decentralized counterpart in the public and private replication scenarios, respectively.
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    EASER: energy aware scalable and reactive replication protocol for MANETs
    (Springer, 2016) N/A; N/A; Department of Computer Engineering; Department of Computer Engineering; Azar, Saeed Nourizadeh; Karaağaçlı, Kaan; Özkasap, Öznur; PhD Student; Undergraduate Student; Faculty Member; Department of Computer Engineering; N/A; Graduate School of Sciences and Engineering; College of Engineering; College of Engineering; N/A; N/A; N/A; 113507
    Mobile ad hoc networks (MANETs) depend on the nodes' collaboration to communicate and transfer data, and scaling the network size up greatly increases the energy needed to transfer data among far away nodes. To preserve nodes' energy and increase the network lifetime, data replication protocols have been proposed, which mainly increase data availability by creating nearby local copies of required data. In this work, first we provide a review of energy aware data replication protocols in MANETs. Then, by considering nodes' energy consumption, we propose EASER: Energy Aware Scalable and rEactive data Replication protocol. Our simulation results and comparison with SCALAR, energy aware ZRP and AODV protocols show that EASER provides improved network lifetime and data accessibility as the network size scales up with considering node energy levels.