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Yayın Enabling cooperation, resource allocation and receiver selection across cells: complementary fractional frequency reuse(IEEE, 2013) Bakşi, Saygın; Kaya, Onur; Bıyıkoğlu, TürkerFor a multi-cell multiple access channel, we develop a comprehensive cooperative communication framework: we propose a novel complementary fractional frequency reuse (FFR) strategy tailored specifically for pairwise user cooperation, also taking into account cell sectoring. This strategy allows the cell edge users not only to pool their resources and cooperate across cells, but also to choose the best receiver. We divide the users into cooperating inner and outer user pairs, and assign each pair orthogonal resources using OFDMA. We employ pairwise bidirectional cooperation based on block Markov superposition encoding among user pairs. We derive the achievable rates, while taking into account the geometry dependent interference at the users and the receiver. We find the jointly optimal power allocation, partner selection and receiver selection strategies that maximize the sum rate of the system. We then propose a heuristic matching algorithm, which operates based only on user and receiver locations. We compare the performance of our proposed strategies with several non-cooperative models, and demonstrate that the sum rate can nearly be doubled, while using the same resources.Yayın İki qubit’lik kuantum haberleşme ağlarının eş zamanlılık donanıklık ölçütü ile kuantum Fisher bilgisinin analizi(IEEE, 2014-06-12) Erol, Volkan; Buğu, Sinan; Özaydın, Fatih; Altıntaş, Azmi AliKuantum dolanıklık, kuantum haberleşme mühendisliğinin en temel kavramlarından biridir. Kuantum sistemlerin dolanıklık ölçütlerine göre sıralanması günümüzde oldukça çok çalışılan konulardan birisidir. İki parçacıklı iki seviyeli sistemlerin (qubit) sıralaması konusu, çok bilinen Eş Zamanlılık (Concurrence), Negatiflik (Negativity) ve Dolanıklığın Göreceli Entropisi (REE) ölçütlerine göre çeşitli araştırmacılar tarafından çalışılmıştır[1-5]. Biz bu çalışmada, iki qubit kuantum sistemlerin sıralamasını Kuantum Fisher Bilgisi ve Eş Zamanlılık dolanıklık ölçütünü karşılaştıracak şekilde analiz etmekteyiz. Çalışma özelinde, bin adet rastgele türetilmiş iki qubit sistemin Eş Zamanlılık değerleri hesaplanmakta; elde ettiğimiz bu sonuçların iki qubit sistemlerde Kuantum Fisher Bilgisi ile karşılaştırılması yapılmakta ve aralarındaki ilginç farklar gözlemlenmektedir.Yayın Cyclostationarity-based robust algorithms for QAM signal identification(IEEE-INST Electrical Electronics Engineers Inc, 2012-01) Dobre, Octavia Adina; Öner, Mustafa Mengüç; Rajan, Sreeraman; Inkol, RobertThis letter proposes two novel algorithms for the identification of quadrature amplitude modulation (QAM) signals. The cyclostationarity-based features used by these algorithms are robust with respect to timing, phase, and frequency offsets, and phase noise. Based on theoretical analysis and simulations, the identification performance of the proposed algorithms compares favorably with that of alternative approaches.Yayın Quantum fisher information of a 3 x 3 bound entangled state and its relation with geometric discord(Springer/Plenum Publishers, 2015-09) Özaydın, FatihRecent studies on quantum Fisher information (QFI) have been focused mostly on qubit systems within the context of how entanglement helps surpassing the classical limit of separable states and the limit that a given entangled system can achieve for parameter estimation. However, there are only a few works on bound entangled systems. In this work, we study the QFI of a system of the smallest dimension that bound entanglement can be observed: A bipartite quantum system of two particles of three-levels each. An interesting property of this state is that depending only on a parameter, the state can be separable, bound entangled or free entangled. We show that QFI exhibits a smooth and continues increase with respect to this parameter throughout the transition from separable to bound entangled and from bound entangled to free entangled regions. We show that in any region, this state is not useful for sub-shot noise interferometry. We also relate the QFI of this state with its geometric discord and show how these two properties exhibit a similar behavior throughout this transition.
