Yazar "Koca, Mutlu" seçeneğine göre listele

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    Cooperative multiple access under energy harvesting constraints
    (Institute of Electrical and Electronics Engineers Inc, 2015) Su, Nuğman; Kaya, Onur; Ulukuş, Şennur; Koca, Mutlu
    We consider a cooperative multiple access channel (MAC) with two energy harvesting transmitters. The transmitters perform delay constrained transmission, i.e., every information block is encoded, transmitted and decoded between two consecutive energy harvests. We aim to maximize the achievable departure region over a finite transmission duration. We formulate the departure region maximization as a convex optimization problem. We propose an iterative algorithm which uses a directional waterfilling strategy to calculate the optimal power components. The departure region obtained by cooperation is shown to be significantly larger than that of a MAC without cooperation under the same energy arrival patterns. As a special case, we also analyze an energy harvesting relay channel with full duplex cooperation.
  • Küçük Resim
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    Delay tolerant cooperation in the energy harvesting multiple access channel
    (IEEE, 2016) Kaya, Onur; Su, Nuğman; Ulukuş, Şennur; Koca, Mutlu
    We consider the optimum transmit scheduling problem for a two user energy harvesting cooperative multiple access channel. We assume a slotted model where energy harvests in each slot are known a priori. We propose a delay tolerant cooperation model: the transmitters create common information in a given slot, but need not cooperatively send the created common information immediately; they may relegate all or part of the cooperative message transmission to upcoming slots. We propose a modified block Markov superposition coding scheme based on message re-partitioning, that spans multiple slots. We characterize the corresponding achievable departure region by a deadline, and maximize it subject to energy harvesting constraints. We show that, delay tolerant cooperation need not necessarily improve the departure region over delay constrained cooperation, and derive a sufficient condition for the equivalence of the two policies. We compare optimal delay constrained and delay tolerant cooperation policies, and their achievable departure regions via simulations.
  • Küçük Resim
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    Enerji depolama kayıpları altında enerji hasat eden işbirlikli çoklu erişim
    (IEEE, 2017-06-27) Su, Nuğman; Kaya, Onur; Koca, Mutlu
    Bu bildiride, enerji hasat eden iki vericiyle bir alıcının haberleştiği işbirlikli bir çoklu erişim kanalı için, sonlu batarya sığası ve enerji depolama kayıpları altında ulaşılabilir gönderim bölgesi eniyileme problemini çözüyoruz. İşbirliğinin gecikme kısıtlı ve gecikme toleranslı olduğu durumları ayrı ayrı ele alarak, her iki durumda eniyi iletim gücü ve hızı dağılımının batarya limitleri ve verimsizliğine göre değişimini inceliyoruz. Gecikme kısıtlı ve toleranslı durumların gönderim alanlarını bulup karşılaştırıyoruz.