WoS İndeksli Yayınlar Koleksiyonu / WoS Indexed Publications Collection

Permanent URI for this collectionhttps://hdl.handle.net/11147/7150

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2017 - 201912020 - 20255

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Access Right: Closed AccessAuthor: search.filters.author.Ozbek, Berna

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Now showing 1 - 6 of 6
  • Article
    HAPS Assisted Cooperative Offloading for Space–Air–Ground Integrated Networks
    (Elsevier GmbH, 2025) Yilmaz, Saadet Simay; Ozbek, Berna; Erdogan, Eylem
    Mobile edge computing (MEC) has significantly enhanced computational capabilities at the network edge, enabling computation-intensive applications. However, traditional MEC implementations face significant challenges in areas without reliable terrestrial network infrastructure, such as rural regions or disaster-affected zones. To address this, we present a novel MEC-enabled space-air-ground integrated network (SAGIN) framework that combines high-altitude platform station (HAPS) and low Earth orbit (LEO) satellite to ensure comprehensive coverage and reduce execution delays for ground users (GUs) in areas lacking terrestrial infrastructure. By leveraging the complementary capabilities of HAPS, which provide wide-area coverage and reliable connectivity, and LEO satellites, which offer high-throughput communication, the proposed SAGIN framework enhances computation offloading. We propose a cooperative approach between GUs and the LEO satellite via the HAPS to maximize offloaded data while satisfying stringent delay constraints under a partial offloading mode. A nonlinear optimization problem is formulated to minimize execution delay while increasing offloaded data by jointly optimizing task offloading decisions and resource allocation between the HAPS and LEO satellite. Simulation results show that the proposed cooperative offloading scheme significantly outperforms random and non-cooperative schemes considering execution delay. These results highlight that the proposed cooperative, HAPS-assisted SAGIN framework effectively enables low-delay edge computing in infrastructure-limited regions.
  • Article
    Citation - WoS: 2
    Semantic Communications in 6G: Coexistence, Multiple Access, and Satellite Networks
    (IEEE-Inst Electrical Electronics Engineers Inc, 2025) Ahmed, Ishtiaque; Sun, Yingzhuo; Fu, Jingwen; Kose, Alper; Musavian, Leila; Xiao, Ming; Ozbek, Berna
    The exponential growth of wireless users and bandwidth constraints necessitates innovative communication paradigms for next-generation networks. Semantic Communication (SemCom) emerges as a promising solution by transmitting extracted meaning rather than raw bits, enhancing spectral efficiency and enabling intelligent resource allocation. This paper explores the integration of SemCom with conventional Bit-based Communication (BitCom) in heterogeneous networks, highlighting key challenges and opportunities. We analyze multiple access techniques, including Non-Orthogonal Multiple Access (NOMA), to support coexisting SemCom and BitCom users. Furthermore, we examine multi-modal SemCom frameworks for handling diverse data types and discuss their applications in satellite networks, where semantic techniques mitigate bandwidth limitations and harsh channel conditions. Finally, we identify future directions for deploying semantic-aware systems in 6G and beyond.
  • Conference Object
    User Selection for Secure Massive Mimo Based Mobile Edge Computing With Delay-Sensitive Applications
    (IEEE, 2025) Yilmaz, Saadet Simay; Ozbek, Berna
    Mobile edge computing (MEC) has been a promising technology that leverages cloud computing capabilities at the network edge to address compute-intensive and delay-sensitive applications of mobile users with limited resources. Employing massive multiple-input multiple-output (mMIMO) and nonorthogonal multiple access (NOMA) in the MEC system facilitates simultaneous task offloading for multiple users, resulting in increased spectral efficiency and decreased offloading delay. Despite the great potential of the mMIMO-NOMA-based MEC system, offloading computation tasks to MEC servers can introduce inherent security concerns and vulnerabilities. We address a notable gap in the existing literature by investigating the effect of user selection to minimize the delay in MEC while enhancing the security of this framework. Specifically, this paper presents a user selection strategy for an uplink mMIMO-NOMA-based secure MEC system in the presence of a malicious eavesdropper (Eve) to minimize offloading and computing delays, subject to the transmit power, computing resource, and secrecy rate constraints with remote computing. We propose a two-step secure user selection algorithm and solve the optimization problem with the active-set algorithm. The simulation results demonstrate the effectiveness of the proposed user selection strategy on secure MEC with a malicious Eve by minimizing the task execution delay compared to the benchmark schemes.
  • Conference Object
    Citation - Scopus: 2
    Reconfigurable Intelligent Surface Assisted Pnc System With Multiple Antennas
    (IEEE, 2023) Ilguy, Mert; Ozbek, Berna; Musavian, Leila; Mumtaz, Rao
    Reconfigurable Intelligent Surface (RIS) is one of the promising key technologies for next generation wireless communication systems since it smartly controls wireless propagation environments. Besides, the combination of wireless physical network coding (PNC) and multiple antennas improves the overall system performance. In this paper, we propose an efficient RIS-assisted PNC with multiple antennas to reduce delay and error probability while establishing reliable transmission between the users which are far from each other and communicating via a base station with the help of the RISs. The extensive performance results are provided for the proposed scheme for the RIS-assisted PNC with multiple antennas.
  • Conference Object
    Detection Scheme for Pnc-Based Cell-Free Mimo Systems
    (IEEE, 2023) Cumali, Irem; Ozbek, Berna; Kurt, Gunes Karabulut
    Cell-free multiple-input multiple-output (cell-free MIMO) is a promising concept to overcome inter-cell interference and avoid non-uniform data rates among users by combining the best features of ultra-dense networks and MIMO. Hence, cell-free MIMO can fulfill the increasing demand on data rate with uniformly good coverage for the sixth-generation (6G) wireless communications. In addition to that, physical-layer network coding (PNC) reduces the transmission delay since it requires only two time slots instead of four time slots to exchange information between two users. In this paper, we propose a novel scheme called PNC-based cell-free MIMO to improve reliability further while reducing the transmission delay. We demonstrate the effectiveness of the proposed scheme regarding the bit error rate in different system configurations. The proposed PNC-based cell-free MIMO achieves significantly lower error probability than the conventional cell-free MIMO.
  • Conference Object
    Zamanla İlintili Kanallarda Güvenli MISO Sistemlerinin Başarımı
    (IEEE, 2017) Ozdogan, Ozgecan; Ozbek, Berna; Kurt, Gunes Karabulut
    We consider the problem of secure communication with multiple antenna transmission in temporally correlated channels. In order to achieve a secrecy gain, a channel state information of the intended receiver at the transmitter is required. In this work, we present a limited feedback link by employing differential codebook which utilizes the temporal correlation properties of the wireless channels for a secure multi-antenna system. The secrecy performances are shown for different channel correlations.