Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7148
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Article Citation - WoS: 2Citation - Scopus: 2Deep Learning Based Adaptive Bit Allocation for Heterogeneous Interference Channels(Elsevier, 2021) Aycan, Esra; Özbek, Berna; Le Ruyet, DidierThis paper proposes an adaptive bit allocation scheme by using a fully connected (FC) deep neural network (DNN) considering imperfect channel state information (CSI) for heterogeneous networks. Achieving an accurate CSI has a crucial role on the system performance of the heterogeneous networks. Different quantization techniques have been employed to reduce the feedback overhead. However, the system performance cannot increase linearly with the number of bits increasing exponentially. Since optimizing the total number of bits is too complex for the entire network, an initial step is performed to distribute the bits to each cell in the conventional method. Then, the distributed bits are further allocated to each channel optimally. In order to enable direct allocation for the entire network, a FC-DNN based method is presented in this study. The optimized number of bits can be directly obtained for a different number of bits and scenarios by the proposed approach. The simulations are performed by using various scenarios with different allocation schemes. The performance results show that the DNN based method achieves a closer performance to the conventional approach. (C) 2021 Elsevier B.V. All rights reserved.Conference Object Citation - Scopus: 2Genetik Algoritma ile Çok Kullanıcı Dfbç Sistemleri için Toplam Veri Hızı Enbüyüklemeli Uyarlanır Alttaşıyıcı ve Bit Yerleşimi(Institute of Electrical and Electronics Engineers Inc., 2008) Özbek, Berna; Le Ruyet, DidierIn this work, we perform the adaptive subcarrier and bit allocation to maximize the sum data rate for multiuser OFDM systems using genetic algorithm. Since the convergence time of the genetic algorithm could be slow, we propose to use a different initial condition to accelerate it without increasing the complexity of genetic algorithm and sacrificing the performance of the system. We obtain the simulation results and compare them with the classical methods. We show that the genetic algorithm with proposed initial condition gives better performances than the classical ones for sum data rate maximized allocation.Conference Object Citation - WoS: 2Citation - Scopus: 3Heterojen ağlarda iyileştirilmiş veri katarı seçimi ile girişim hizalama(IEEE, 2015) Le Ruyet, Didier; Aycan, Esra; Özbek, BernaIn this article, interference that occurs in heterogeneous networks is studied and a new stream selection approach with an interference alignment solution is presented. In the proposed algorithm, stream selection starts with the streams that belongs to the pico cell users and continues to select the strongest streams that increase the total sum rate. The power of each stream with the precoding and the postcoding vectors are calculated by performing singular value decomposition (SVD). Virtual channels that belong to the selected stream are calculated by using precoding and postcoding vectors. After the selection procedure, the interferences between the selected stream and the remaining streams are mitigated by orthogonally projecting the channel matrices of the remaining streams to the virtual channels of the selected stream.Book Citation - Scopus: 17Feedback Strategies for Wireless Communication(Springer, 2014) Özbek, Berna; Le Ruyet, DidierThis book explores the different strategies regarding limited feedback information. The book analyzes the impact of quantization and the delay of CSI on the performance. The author shows the effect of the reduced feedback information and gives an overview about the feedback strategies in the standards. This volume presents theoretical analysis as well as practical algorithms for the required feedback information at the base stations to perform adaptive resource algorithms efficiently and mitigate interference coming from other cells. © 2014 Springer Science+Business Media New York. All rights are reserved.Conference Object Citation - Scopus: 1Interference Management for Multiuser Multiantenna Ofdma Underlaying Device-To Communications(IEEE, 2017) Özbek, Berna; Pischella, Mylene; Le Ruyet, DidierUnderlaying device-to-device (D2D) transmission in cellular wireless systems is one of the promising transmission techniques for fifth generation (5G) and beyond 5G applications. Nevertheless, the interference between the D2D pairs, the interference from cellular users to D2D receivers and the interference that affects the cellular communications should be mitigated to increase the overall system performance. In this paper, we propose interference management techniques for D2D underlaying communications in multiuser multiantenna orthogonal frequency division multiple access (OFDMA) systems. Our goal is to increase the data rate of both the cellular users and D2D pairs by performing interference management in frequency, power and spatial dimensions. The performance evaluations illustrate the effectiveness of the proposed algorithm in terms of average data rate and average transmitted power for both cellular users and D2D pairs.Conference Object Citation - WoS: 1Citation - Scopus: 1Interference-Based Clustering for Mimo D2d Underlay Communications(IEEE, 2018) Pischella, Mylene; Özbek, Berna; Le Ruyet, DidierClustering of Device-to-Device (D2D) pairs with cellular transmissions is particularly challenging to manage interference in future fifth generation networks. D2D pairs should coexist with cellular users in underlay scenario, taking advantage of frequency and spatial dimensions. We consider a Multiple Input Multiple Output (MIMO) channel where all users (whether cellular or devices) are equipped with N > 1 antennas, and the Base Station (BS) has M >= N antennas. Interference between D2D pairs, between D2D transmitters and the BS and between cellular users and D2D receivers is then managed by determining clusters of D2D pairs and cellular users with very low relative interference levels. Clusters are obtained after graph-coloring on a pairwise interference-leakage based matrix. Then, several Resource Blocks (RB) allocation algorithms are proposed, with various fairness levels. A final orthogonalization step using Minimum Mean Square Error (MMSE) may be added at the BS in order to further reduce interference. Simulation results show very large D2D data rates improvements, while cellular data rates degradation due to interference can be controlled.Conference Object Citation - Scopus: 2Message-Passing Algorithm for Sum-Rate Maximization in Multi-Antenna Underlay D2d Communications(IEEE, 2018) Özbek, Berna; Pischella, Mylene; Le Ruyet, DidierIn this paper, we propose a resource allocation of device-to-device (D2D) communications underlaying multiantenna cellular systems by employing message-passing algorithm. It is possible to construct the factor graph of the D2D pairs by considering the interference power at the base station and among the D2D pairs. The goal is to avoid interfering the cellular transmission while increasing the sum data rate of D2D pairs. We show that the proposed resource allocation based on message passing algorithm allow us to almost reach the performance of the exhaustive search and outperforms the random allocation. Since the associated factor graph is not fully connected, the complexity of the algorithm is significantly reduced compared to the exhaustive search. © 2018 IEEE.Article Citation - WoS: 16Citation - Scopus: 23Energy Efficient Resource Allocation for Underlaying Multi-D2d Enabled Multiple-Antennas Communications(Institute of Electrical and Electronics Engineers Inc., 2020) Özbek, Berna; Pischella, M.; Le Ruyet, DidierEnergy efficiency has a significant importance to optimize the wireless communications systems by providing high data rates. In order to develop energy efficient systems, one of the promising methods is to use multiple device-to-device (D2D) underlaying multiple antenna cellular systems. The interference from cellular users to D2D pairs, the interference between D2D pairs and the interference at the base station (BS) caused by D2D pairs occur in these communications systems. In this article, we propose energy efficient resource allocation algorithms for underlaying multi-D2D enabled multiple-antennas communications by employing different multiple antenna processing techniques at the BS. A joint method based on Dinkelbach algorithm and Message Passing Algorithm (MPA) and an approach based on deep learning with multi-layer artificial neural network are proposed to maximize the global energy efficiency (GEE) while satisfying the data rate requirements of both cellular users and D2D pairs. In MPA, the factor graph of the D2D pairs is constructed by taking into account the interference among the D2D pairs and the interference level at the BS to avoid any interruption in the cellular transmission. By relying on the training based on the proposed joint algorithm, a deep neural network approach is presented for off-line implementation. The performance results of the proposed energy efficient resource allocation algorithms show the superiority of multi-D2D communications over conventional single-D2D communications. © 1967-2012 IEEE.Article Citation - WoS: 8Citation - Scopus: 9Dynamic Shared Spectrum Allocation for Underlaying Device-To Communications(Institute of Electrical and Electronics Engineers Inc., 2017) Özbek, Berna; Pischella, Mylene; Le Ruyet, DidierThis article provides an overview on spectrum sharing in D2D underlaying communications for 5G and beyond 5G applications. Various spectrum sharing algorithms are summarized within a framework of underlaying D2D communications in cellular networks to increase spectrum efficiency. Dynamic spectrum sharing algorithms in the frequency, power, and spatial dimensions are proposed for underlaying D2D communications with both single antenna and multiple antennas at the base station. Performance evaluations show the effectiveness of the proposed algorithms in terms of average data rate per D2D pair.Conference Object Heterojen Ağlarda Veri Katarı Seçimi Tabanlı Girişim Hizalama için Uyarlamalı Sınırlı Geri Besleme Yöntemi(Institute of Electrical and Electronics Engineers Inc., 2016) Aycan, Esra; Özbek, Berna; Le Ruyet, DidierBu bildiride, sınırlı geri beslemeli heterojen ağlar için veri katarı seçimi tabanlı bir girişim hizalama yöntemi sunulmuştur. Sunulan veri katarı seçimi yöntemi, veri katarlarını ilk olarak piko kullanıcılarından seçmeye başlar, daha sonra veri hızını artıran en güçlü veri katarı ile seçim işlemi devam eder ve tüm kullanıcıların en az bir veri katarının olması sağlanır. Seçim işleminden sonra, seçilen veri katarı ile diğerleri arasında oluşan girişimler ortogonal projeksiyonlarla önlenir. Sınırlı geri beslemeli kanalda toplam kapasite, uyarlanır bit paylaşımıyla iyileştirilmektedir.