Electrical - Electronic Engineering / Elektrik - Elektronik Mühendisliği

Permanent URI for this collectionhttps://hdl.handle.net/11147/11

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Institution Author: search.filters.institutionAuthor.Baştürk, İlhanLanguage: search.filters.language.en

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Now showing 1 - 5 of 5
  • Article
    Citation - WoS: 9
    Citation - Scopus: 10
    Radio Resource Management for User-Relay Assisted Ofdma-Based Wireless Networks
    (Urban und Fischer Verlag GmbH und Co. KG, 2016) Baştürk, İlhan; Özbek, Berna
    Orthogonal frequency division multiple access (OFDMA) based relay assisted networks are important for current and next-generation wireless networks since they have great potential to provide high data rate to users at anywhere, anytime. Towards that end, fixed relay assisted OFDMA networks are commonly utilized by the operators. However, they require supplementary costly infrastructure. User-relay assisted OFDMA-based networks are promising candidates to fulfill the demanding coverage and capacity requirements of future wireless networks in a cost efficient way. Thus, they have become popular as a complementary solution to fixed relay networks. Generic frame structure that divides the resource allocation frame into two subframes is mostly used in the literature for fixed and user-relay assisted networks in which it is assumed that a user can act as a destination and a relay simultaneously. However, it may be difficult to apply this assumption to practical systems because of the limitations of the current transceiver design. Thus, we propose a novel frame structure for user-relay assisted OFDMA-based wireless networks in order to cope with these drawbacks. The efficient radio resource management algorithms including relay selection and resource allocation are developed in order to exploit the opportunities of the proposed frame structure.
  • Conference Object
    Citation - Scopus: 5
    Queue-Aware Resource Allocation for Ofdma-Based Mobile Relay Enhanced Networks
    (VDE Publishing House, 2013) Baştürk, İlhan; Özbek, Berna; Le Ruyet, Didier
    Mobile relay assisted OFDMA networks that are considered as a good candidate in future deployment scenarios for coverage extension and lower deployment costs are promising solutions for provision of ubiquitous high-data-rate services in wide coverage areas. However, it is required to design efficient resource allocation algorithms to exploit these opportunities. Thus, this paper designs an heuristic resource allocation algorithm based on the queue and channel state information of the users for mobile relay enhanced OFDMA networks. The proposed queue aware algorithm is appropriate for the realistic scenarios and use system resources efficiently. Numerical results revealed that the mobile-relay enhanced scheme improves coverage and assisting users having unfavorable channel conditions such as cell-edge users by increasing the data rate compared to existing fixed-relay enhanced and non-relaying schemes. © VDE Verlag GMBH.
  • Conference Object
    Citation - Scopus: 9
    Radio Resource Management for Ofdma-Based Mobile Relay Enhanced Heterogenous Cellular Networks
    (Institute of Electrical and Electronics Engineers Inc., 2013) Baştürk, İlhan; Özbek, Berna; Edemen, Çağatay; Tan, Ahmet Serdar; Zeydan, Engin; Ergüt, Salih
    In this paper, we focus on the radio resource management problem for the Orthogonal Frequency Division Multiple Access (OFDMA)-based mobile relay-enhanced het erogenous cellular networks. We combine mobile relaying and data offloading scenarios to increase the capacity of the system and cope with the mobile data traffic volume that is increased by the number of wireless subscribers accessing mobile data services. We propose network interface selection, relay selection and resource allocation solutions for this scenario and show effect of relaying and data offloading on the system capacity and on the ratio of satisfied users. © 2013 IEEE.
  • Conference Object
    Citation - Scopus: 2
    Fairness Aware Resource Allocation for Downlink Miso-Ofdma Systems
    (Institute of Electrical and Electronics Engineers Inc., 2012) Baştürk, İlhan; Özbek, Berna
    In this paper, a resource allocation problem for downlink multiple input-single output orthogonal frequency division multiple access (MISO-OFDMA) systems is investigated. The problem is defined as maximizing the minimum user rate with the constraints of total power and bit error rate (BER). Since it is difficult to obtain the optimal solution to this problem, a suboptimal but efficient solution is proposed based on zero forcing beamforming (ZFBF) to reduce computational complexity. The proposed algorithm is a fairness aware radio resource allocation algorithm that shares the resources equally among the users who has different distances from the Base Station (BS). The simulation results show that the proposed algorithm satisfies the fairness criterion having higher data rates compared to the existing algorithms. © 2012 IEEE.
  • Conference Object
    Citation - WoS: 1
    Citation - Scopus: 3
    Iterative Em-Based Channel Estimation for Stbc-Ofdm
    (Institute of Electrical and Electronics Engineers Inc., 2009) Baştürk, İlhan; Özbek, Berna
    In this paper, an iterative EM based channel estimation algorithm is studied for STBC-OFDM systems. Compared to the time domain EM based channel estimation algorithm which needs matrix inversion, a frequency domain EM based channel estimation algorithm is proposed by estimating the channel coefficients for each subcarrier. The proposed channel estimation algorithm decreased the complexity without sacrificing the performance. The time domain and proposed frequency domain EM based channel estimation algorithms are compared in terms of bit error rate (BER), mean square error (MSE) and the number of iterations used in the EM algorithm.