Electrical - Electronic Engineering / Elektrik - Elektronik Mühendisliği
Permanent URI for this collectionhttps://hdl.handle.net/11147/11
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Conference Object Ofdm Sistemler için Pilot Tabanlı Yinelemeli Kanal Kestirimi(IEEE, 2008) Baştürk, İlhan; Özbek, BernaIn this study, pilot-based iterative channel estimation, which use virtual pilots, is proposed for OFDM systems In order to find final channel estimates, instead of averaging the group estimates, which are found by virtual pilots, it is proposed to combine them by taking into account their reliabilities that are calculated by using probability density function. Then the proposed method is compared to Expectation-Maximization (EM) algorithm with respect to performance and computational complexity. The performance results are given in terms of Bit Error Rate (BER) and Mean Squared Error (MSE). ©2008 IEEE.Conference Object Yazılım Tabanlı Radyolarda Karşılıklı Kanal Özelliğinin İncelenmesi(Institute of Electrical and Electronics Engineers Inc., 2016) Uslu, Merve; Tuğrel, Halim Bahadır; Karabulut Kurt, Güneş; Özbek, BernaKablosuz haberleşme sistemlerinde, kanal kestirimi çok önemli bir yer tutmaktadır. Bu çalışmada A ve B, iki haberleşme düğümü olduğu varsayıldığında, A düğümünden B düğümüne olan kanal için elde edilen kanal katsayıları ile, B düğümünden A düğümüne olan kanal için elde edilen kanal katsayılarının benzerliği incelenmiştir. Karşılıklı kanal özelliğinden dolayı bu kanalların birbirine benzer çıkmaları beklenmektedir. Bu çalışmada, laboratuvar ortamında yazılım tabanlı radyo kitleri kullanılarak karşılıklı kanal özelliği test ortamında test edilmiş, bu iki kanal katsayılarının genlik ve faz ortalama değerleri karşılaştırılmıştır.Article Citation - WoS: 2Citation - Scopus: 2Iterative Channel Estimation for Higher Order Modulated Stbc-Ofdm Systems With Reduced Complexity(Korean Society of Internet Information, 2016) Baştürk, İlhan; Özbek, BernaIn 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.Conference Object Citation - WoS: 1Citation - Scopus: 3Iterative Em-Based Channel Estimation for Stbc-Ofdm(Institute of Electrical and Electronics Engineers Inc., 2009) Baştürk, İlhan; Özbek, BernaIn 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.