Ali ÖZEN | Büşra CENİKLİOĞLU

Bildiri | 2018 | IEEE 41th International Conference on Telecommunications and Signal Processing, TSP 2018 , pp.13 - 16

In this study, a novel zero tail discrete wavelet transform spread orthogonal wavelet division multiplexing (ZT DWT-S OWDM) waveform design has been proposed as a solution to the problem of poor peak to average power ratio (PAPR) performance of conventional orthogonal frequency division multiplexing (OFDM) systems. The effects of different waveletfamilies such as Haar, Daubechies, Symlets, Coiflets and Bi-Orthogonal on PAPR performance of ZT DWT-S OWDM systems are investigated. Computer simulation studies are carried out to compare the ZT DWT-S OWDM waveform with the conventional OFDM and zero-tail discrete Fourier transform spread . . .OFDM (ZT DFT-S OFDM) waveforms. The results show that the ZT DWT-S OWDM waveform has better PAPR performance than the conventional OFDM and ZT DFT-S OFDM waveforms. In particular, it is observed that ZT DWT-S OWDM using Bi-Orthogonal wavelet family has the best PAPR performance. Daha fazlası Daha az

Ali ÖZEN

Bildiri | 2018 | IEEE 41th International Conference on Telecommunications and Signal Processing, TSP 2018 , pp.565 - 568

In optical communication, which is an important part of the Radio over Fiber (RoF) systems, coherent optical OFDM (CO-OFDM) systems allow the use of amplitude and phase belong to the light at the same time for data transmission. However, the data transmission speed and distance of the COOFDM system are limited by optical channel impairment effects. One of the major disadvantages of CO-OFDM systems is its sensitivity to fiber nonlinearity effects. For this reason, in order to be used the new signal processing techniques efficiently in the receiver, the optical channel information must be estimated and the received signal must be equa . . .lized. In this work, different equalizer constructions are investigated and a frequency domain channel equalizer used in the novel DWT-based CO-OFDM system has been proposed. With the simulation studies made, the equalizers were compared and the results were given with different changes. From the obtained simulation results, it is seen that the proposed method provides about 5.5 OSNR gain for 1E-4 BER value. Daha fazlası Daha az

Ali ÖZEN

Bildiri | 2017 | IEEE 25th Signal Processing and Communications Applications SIU 2017 , pp.1 - 4

A novel single carrier frequency domain channel equalizer (SC-FDE) based on discrete wavelet transform (SCDWT-FDE) has been proposed to improve the performance of conventional SC-FDE in this paper. Computer simulations have been performed to verify the performance of the proposed method in stationary and non-stationary frequency selective Rayleigh fading channels. The obtained simulation results using SC-FDE physical layer specifications have demonstrated that the proposed SC-DWT-FDE method has considerably better performance and carrier frequency offset (CFO) tracking than conventional SC-FDE system.

Ali ÖZEN | Kudret KARAERİK | Elif Büşra TUNA | Yusuf İslam TEK | Hayriye SİNOP | Sabiha YAŞAR | Büşra AVCI | Gazihan AYKIRI

Bildiri | 2020 | IEEE 2nd International Conference on Electrical, Communication and Computer Engineering, ICECCE 2020 , pp.828 - 831

In this paper, combining with the fast Walsh Hadamard transform (FWHT) to improve the performance of the double-tree complex wavelet transform (DTCWT) based OFDM technique developed to eliminate the disadvantages of the orthogonal frequency division multiplexing (OFDM) system is suggested. In order to test the achievement of the proposed DTCWT FWHT OFDM method, computer simulation studies are performed in AWGN and flat Rayleigh fading channel environments. In addition, peak to average power ratio (PAPR) simulations, which are one of the major disadvantages of the classical OFDM system, are also realized. From the achieved simulation . . . results, it is seen that the suggested method has better performance than classical OFDM, Discrete Wavelet Transform (DWT) based OFDM and DTCWT OFDM techniques for both performance metrics Daha fazlası Daha az

Ali ÖZEN

Makale/Derleme | 2016 | OPTOELECTRONICS AND ADVANCED MATERIALS-RAPID COMMUNICATIONS

In this paper, a novel discrete wavelet transform-based coherent optical OFDM system, which improved the performance of the frequency domain equalizer by using discrete wavelet transform in the conventional coherent optical OFDM system, is proposed as a solution to data transmission speed and distance problems limited by the fiber nonlinearity and optical noise of optical channels. The greatest novelty of this study is that the discrete wavelet transforms and coherent optical OFDM systems are combined in the proposed technique. Simulation results are shown to verify the effectiveness of the proposed system at high launch power level . . .s where fiber nonlinearity is significant. Daha fazlası Daha az