Electrical - Electronic Engineering / Elektrik - Elektronik Mühendisliği

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

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Author: search.filters.author.Baştürk, İlhanSubject: search.filters.subject.Orthogonal frequency division multiplexing

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Now showing 1 - 2 of 2
  • Article
    Citation - WoS: 2
    Citation - Scopus: 2
    Iterative Channel Estimation for Higher Order Modulated Stbc-Ofdm Systems With Reduced Complexity
    (Korean Society of Internet Information, 2016) Baştürk, İlhan; Özbek, Berna
    In this paper, a frequency domain Expectation-Maximization (EM)-based channel estimation algorithm for Space Time Block Coded-Orthogonal Frequency Division Multiplexing (STBC-OFDM) systems is investigated to support higher data rate applications in wireless communications. The computational complexity of the frequency domain EM-based channel estimation is increased when higher order constellations are used because of the ascending size of the search set space. Thus, a search set reduction algorithm is proposed to decrease the complexity without sacrificing the system performance. The performance results of the proposed algorithm is obtained in terms of Bit Error Rate (BER) and Mean Square Error (MSE) for 16QAM and 64QAM modulation schemes.
  • 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.