Browsing by Subject "Frequency division multiple access"

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    SDN/NFV based Secure SCMA design in SDR
    (Institute of Electrical and Electronics Engineers Inc., 2021) Erel-Ozcevik M.; Tekce F.
    Due to increased mMTC devices in 5G, OFDMA has not been a solution for resource allocation in SDR. Therefore; SCMA which is one of the code domain NOMA has been using in such overloaded cases. As distinct from OFDMA, it uses also the constellation diagram as an addition to frequency and time domains in resource mapping to the mobile user equipment. The current studies do not consider UE prioritization while code allocation in SCMA is believed to enhance QoS of the whole topology. Moreover, due to the nature of SCMA, protecting the privacy of UE has become harder than conventional allocation strategies. The implementation details of secure SCMA does not consider by handling low OPEX/CAPEX. Therefore, in this paper, we introduce a novel SDN/NFV based SDR by handling these 5G paradigms into the same platform to overcome the aforementioned challenges. With SDN, we newly define a QoS metric; i.e. received power over overloading of SDR, for UE prioritization such as Micro and Macro UE in an SDR. With NFV, SDR can have two virtual roles shown to UEs by Macrocell and Microcell virtual network functions. With SDR, the SCMA code allocation is performed according to defined Macro and Micro codes are taken from generated codebooks. Afterward, it performs the asymmetric encryption algorithm to provide security of code allocations and the privacy of the user. According to performance evaluation; when overloading is 150%, the Micro UEs have 10x better BER than Macro UEs where the QoS is acceptable for the whole topology. © 2021 IFIP.
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    Energy-efficiency maximization for multi-antenna OFDMA networks; [Çok antenli DFBÇE aǧlari için enerji verimliliǧi maksimizasyonu]
    (Institute of Electrical and Electronics Engineers Inc., 2021) Basturk I.
    Energy efficient or green communication has been one of the most important targets of the next generation communication systems in the last years because of the massive energy usage. In the light of these targets, energy efficient communication is studied for the multi-antenna Orthogonal Frequency Division Multiple Access (OFDMA) cellular networks in this study. Energy efficiency maximization problem is defined by considering the quality of service requirements of the users. A solution which allocates sub-bands and power disjointly is proposed for this complex Mixed-integer non-linear programming (MINLP) type problem, which is in the fractional form and contains not only discrete but also continuous parameters. The performance of the proposed solution is evaluated by using simulation results. © 2021 IEEE.