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    Numerology scheduling for PAPR reduction in mixed numerologies
    (IEEE-Institute of Electrical and Electronics Engineers Inc., 2021) Memişoğlu, Ebubekir; Duranay, Ahmet Enes; Arslan, Hüseyin
    The flexible mixed-numerology structure with orthogonal frequency division multiplexing (OFDM) waveform is a key enabler to meet the requirements of various applications in fifth-generation (5G) and beyond wireless networks. However, the high peak-to-average power ratio (PAPR) is still one of the main drawbacks and conventional numerology selection can only provide PAPR reduction for the time-domain numerology multiplexing. In this letter, a novel numerology scheduling (NS) method is proposed to provide PAPR reduction for both time-domain and frequency-domain numerology multiplexing scenarios. For the proposed method, the signal with minimum PAPR is selected from a set of signals with different NS. The simulation results and complexity analysis demonstrate that the proposed method with a linearithmic complexity improves PAPR reduction compared to conventional numerology selection.
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    Phase rotation approach with mixed-numerology architecture for PAPR reduction in 5G and beyond
    (Institute of Electrical and Electronics Engineers Inc., 2023) Duranay, Ahmet Enes; Memişoğlu, Ebubekir; Özbakış, Başak; Arslan, Hüseyin
    For a wide range of service requirements, the 5G-NR offers significant flexibility based on OFDM with numerous numerologies. However, OFDM is recognized to have a significant disadvantage due to a high PAPR. On the other hand, the PAPR reduction for mixed-numerology OFDM has received little attention compared to single-numerology OFDM, despite there being possible challenges and advantages such as computational complexity and new structure opportunity, respectively. In this paper, the phase rotation PAPR reduction approach on mixed-numerology OFDM is proposed for the first time. Unlike the single-numerology approach, the need for additional IFFT and side information overhead is eliminated, and the mixed-numerology transmitter structure is exploited to provide three novel approaches, namely proposed numerology-based (Proposed-NB), proposed symbol-based (Proposed-SB), and proposed location-based (Proposed-LB). Proposed-NB has the same PAPR performance with a lower complexity compared to the partial transmit sequence (PTS) method for single-numerology OFDM. Moreover, the new ability to use multiple phase factors for the same numerology symbols in the defined largest symbol length enhances the PAPR reduction performance further using Proposed-SB. While all symbols are jointly optimized in the Proposed-SB, Proposed-LB drives a sub-optimal solution developed by optimizing the selected symbols. Due where the presence of different symbols duration between numerologies and also consecutive symbols in the same numerology, PAPR reduction performance in Proposed-LB almost reaches the optimum Proposed-SB performances with a lower computational complexity compared to Proposed-SB. The conducted numerical results validate the superiority of the proposed methods for 5G and beyond compared to PTS and numerology scheduling methods.
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    Post-earthquake network restoration statistical seismic road closure prediction and efficient mdru routing
    (2025) Duranay, Ahmet Enes; Kodheli, Xhelja; Abdelhady, Amr; Çelik, Abdulkadir; Eltawil, Ahmed; Arslan, Hüseyin
    Post-earthquake scenarios have brought connectivity challenges to the forefront of research in recent years. Particularly, the randomness and large-scale of road and telecom network infrastructure damage within the aftermath hinders communications coverage restoration during the most critical hours when lives are at stake. This paper proposes a seismic-based post-earthquake city and cellular network model to statistically predict the status of road closures and base station failures based on fundamental earthquake measurements. The presented model considers a generic Manhattan grid-based city model, with buildings featuring random heights. In addition, it quantifies the probability of building collapse and the consequent probability of road closure which accounts for the random debris nature. Moreover, the model accounts for the dependencies between the debris width, height, and the relative location with respect to the earthquake epicenter. Furthermore, a routing algorithm for movable and deployable resource units (MDRUs) that exploits the derived statistical model is proposed to ensure that MDRUs are efficiently deployed and connectivity is restored swiftly. The proposed routing algorithm is extensively tested over a large set of simulation scenarios depicting different earthquake magnitudes and was shown to provide up to 31% traveling time reduction compared to a blind distance-based approach. Finally, the conducted simulations showed the effectiveness of the proposed MDRUs deployment approach in restoring the communications coverage from a signal-to-interference plus noise ratio perspective in the majority of the considered locations.
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    Precoding based cross-tier interference mitigation in centralized-RAN
    (IEEE-Institute of Electrical and Electronics Engineers Inc, 2021) Zegrar, Salah Eddine; Duranay, Ahmet Enes; Arslan, Hüseyin
    This letter considers a two-tier downlink interference problem as a case of study, where macrocell user equipment (UE) shares the same frequency band with femtocell UE and suffers from severe cross-tier interference. Power control is one of the spectrally-efficient techniques used to mitigate the interference. However, it harms femtocell users since the femto base station reduces the transmitted power. In this letter, a novel scheme is proposed to jointly suppress the interference on the macrocell users, and preserve the high data rates required by femtocell users under centralized radio access network. The analytical results well agreed with the conducted simulations, and showed the superiority of the proposed scheme in achieving higher throughput compared to existing schemes.
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    Quantum laboratory setup for future wireless communication systems
    (American Institute of Physics Inc., 2019) Solaija, Muhammad Sohaib J.; Janjua, Muhammad Bilal; Afeef, Liza; Tusha, Armed; Duranay, Ahmet Enes; Arslan, Hüseyin; Hasekio?lu, Orkun
    Fifth generation of wireless communication envisages a diverse network that imposes stringent requirements regarding capacity, reliability, security, latency and seamless connectivity. These lofty goals have driven researchers to look for technologies capable of supporting conventional methods. Application of quantum mechanics to the domain of communications has been considered for a while now but the reliance of any quantum phenomena on experimental verification remains an obstacle in its widespread use. To serve this purpose, we propose establishing a quantum optics laboratory in Turkey which will allow implementation, analysis and investigation of the various promising quantum communication tools. This work is directed towards description and experimental verification of some well-known quantum experiments, from relatively simpler ones such as single or entangled photon generation to the more evolved experiments like quantum random number generation and quantum key distribution.
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    The evaluation of FFR for interference management in coordinated hybrid terrestrial-aerial network
    (Institute of Electrical and Electronics Engineers Inc., 2019) Duranay, Ahmet Enes; Arslan, Hüseyin
    Recent works have tried to incorporate unmanned aerial vehicle (UAV) base stations in conventional networks, however, the inter-cell interference mitigation techniques for such networks have not been studied comprehensively. In this paper, we consider a new heterogeneous cellular network, where terrestrial base stations (TBSs) and low altitude platforms (LAPs) collaborate to construct a hybrid network. We believe that it can serve as the stepping stone to a full-fledged coordinated multi-point implementation for 5G and beyond networks. The proposed network is simple, open to improvement and also makes use of available TBS. It promises to increase minimum signal-to-interference ratio (SIR) value of users and also overall throughput by using fractional frequency reuse. The hovering LAP is used for edge users that have lower SIR than TBSs threshold. Furthermore, we simulated a few scenarios, analyzed the effect of radius and UAV altitude, found optimum values for both.