Ali Özen

Bildiri | 2019 | IEEE 42th International Conference on Telecommunications and Signal Processing, TSP 2019 , pp.660 - 663

In this paper, a new waveform design based on Lifting Wavelet Transform (LWT) is proposed for next generation wireless communication systems. The proposed waveform design (LWT-UFMC) consists of combination of the LWT and universal filtered multi carrier (UFMC) waveform. It is aimed to improve the performance of the UFMC waveform, which is from the 5th Generation (5G) waveform candidates, with the proposed LWT-UFMC waveform. Computer simulation studies are performed to test the achievement of the recommended waveform and to compare with the classical OFDM and UFMC in AWGN and flat Rayleigh fading channels. It is seen that the propose . . .d waveform from the obtained simulation results has the best and highly satisfactory performance. Daha fazlası Daha az

Ali Özen

Bildiri | 2019 | IEEE 42th International Conference on Telecommunications and Signal Processing, TSP 2019 , pp.651 - 654

In this paper, DT-CWT-OFDM waveform based on dual tree complex wavelet conversion (DT-CWT) is introduced to enhance the achievement of the classical OFDM waveform. IFFT/FFT blocks used in the classical OFDM waveform are replaced with IDTCWT/DTCWT blocks in the DT-CWT-OFDM waveform. In order to confirm the achievement of the investigated waveform and compare it with the waveforms of classical OFDM and discrete wavelet conversion based OFDM (DWT-OFDM), computer simulation studies are carried out on AWGN, flat Rayleigh damping and frequency-selective Rayleigh damping channels. It is seen from the attained simulation outcomes that the D . . .T-CWT-OFDM waveform has better achievement than the classical OFDM and DWT-OFDM waveforms and also provides approximately 6 dB SNR gain against the classical OFDM and approximately 1.5 dB SNR gain against the DWT-OFDM for a BER value of 1E-4 Daha fazlası Daha az

Ali ÖZEN

Bildiri | 2019 | IEEE 42th International Conference on Telecommunications and Signal Processing, TSP 2019 , pp.647 - 650

In this paper, color shift keying (CSK) modulation, which is selected as one of the modulation methods in visible light communication systems, is integrated with orthogonal frequency division multiplexing (OFDM) to increase the spectrum yield. However, the conventional fast Fourier transform (FFT) based OFDM needs that the CSK symbols be Hermitian symmetric, resulting in wasted bandwidth. In this study, it is proposed a real Fourier field based CSK OFDM technique using discrete Cosine transform (DCT), which can transform the real-value signal into a real-value signal and eliminate the need for Hermitian symmetry. Thus, the use of sp . . .ectra has been doubled due to the removal of Hermitian symmetry in classical FFT-based OFDM systems. In order to test the achievement of the recommended CSK-modulated DCT-based OFDM (DCT-OFDM) and compare with the classical FFT-based OFDM and discrete sine transform (DST) based OFDM systems computer simulation studies are carried out in additive white Gaussian noise (AWGN) channel environment and a single path channel in indoor environment, where the transmitter and the receiver see each other (Line of sight, LOS). From the computer simulation outcomes, it is observed that approximately 17 dB of SNR gain is obtained with the proposed method for the 1E-3 BER value. Daha fazlası Daha az

Ali ÖZEN

Bildiri | 2019 | 3. International Scientific and Vocational Studies Congress , pp.1 - 6

In this study, zero tail inverse Lifting wavelet transform spread fast Walsh Hadamard transformed OFDM (ZT-ILWTs FWHT OFDM) is recommended as an alternative to the OFDM waveform for the new generation of wireless transmission systems. The recommended waveform is composed of a combination of inverse Lifting wavelet transform (ILWT) and fast Walsh Hadamard transform (FWHT) with OFDM waveform. The proposed waveform is tested with computer simulation studies for bit error rate (BER), peak to average power ratio (PAPR) and out of band emission (OOBE) performance criteria. From the attained results, it is observed that the recommended wav . . .eform is better than classical OFDM and zero-tail discrete Fourier transform spread OFDM (ZT-DFT-S OFDM) waveforms for all three performance criteria Daha fazlası Daha az

Ali ÖZEN

Bildiri | 2018 | IEEE 41th International Conference on Telecommunications and Signal Processing, TSP 2018 , pp.5 - 8

n this paper, it is proposed a new unique word (UW) OFDM waveform based on zero-tail discrete Sine transform spread OFDM (ZT UW DST-S OFDM). The proposed waveform improves the ZT DST-S-OFDM and UW OFDM methods by removing the influence of the data symbols on the tail of the transmitted signal. In this study, the effects of different UW sequences such as Zadoff-Chu, CAZAC, 15 bit PN, 8 bit complementary code keying (CCK), 0-word, 1-word and -1-word on the bit error rate (BER) and channel tracking (Doppler) performance of the proposed ZT UW DST-S OFDM systems are investigated. In order to test the performance of the proposed method, c . . .omputer simulation studies are performed on time invariant and time variant frequency selective Rayleigh fading channels. The obtained results confirm that the proposed waveform has better BER and channel tracking (Doppler) performance than the conventional OFDM and ZT DFT-S OFDM systems. In particular, it is observed that the ZT UW DST-S OFDM using Zadoff-Chu sequence has the best BER and channel tracking performance. Daha fazlası Daha az

Ali ÖZEN

Bildiri | 2018 | IEEE 41th International Conference on Telecommunications and Signal Processing, TSP 2018 , pp.9 - 12

In this paper, zero-tail discrete cosine transform spread OFDM (ZT DCT-S OFDM) waveform is proposed as an alternative to 5th generation (5G) waveform enhancement studies. In order to verify the performance of the proposed method and compare with the conventional OFDM and zero-tail discrete Fourier transform spread OFDM (ZT DFT-S OFDM) systems, computer simulations are performed on time invariant and time variant frequency selective Rayleigh fading channels. The obtained simulation results show that the proposed ZT DCTS OFDM method has better bit error rate (BER) and channel tracking (carrier frequency offset, CFO) performance than c . . .onventional OFDM and ZT DFT-S OFDM systems Daha fazlası Daha az

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 26th Signal Processing and Communications Applications SIU 2018 , pp.1 - 4

Bu bildiride, sıfır sonlu ayrık Sinüs dönüşümü yayılmalı OFDM üzerine kurulan yeni bir unique word (UW) OFDM (ZT UW DST-S OFDM) dalga biçimi önerilmektedir. Önerilen dalga biçimi, veri simgelerinin gönderilen sinyalin kuyruğu üzerindeki etkisini ortadan kaldırarak ZT DST-SOFDM ve UW OFDM yöntemlerini geliştirmektedir. Önerilen yöntemin başarımını test etmek için frekans seçici Rayleigh sönümlemeli kanallarda bilgisayar benzetimleri yapılmaktadır. Elde edilen sonuçlardan önerilen dalga biçiminin klasik OFDM, ZT DFT-S OFDM ve ZT UW DFT-S OFDM sistemlerinden daha iyi tepe ortalama güç oranı (PAPR) ve bit hata oranı (BER) başarımlarına . . .sahip olduğunu doğrulamaktadır. In this paper, it is proposed a new unique word (UW) OFDM waveform based on zero-tail discrete Sine transform spread OFDM (ZT UW DST-S OFDM). The proposed waveform improves the ZT DST-S-OFDM and UW OFDM methods by removing the influence of the data symbols on the tail of the transmitted signal. In order to test the performance of the proposed method, computer simulation studies are performed on frequency selective Rayleigh fading channels. The obtained results confirm that the proposed waveform has better peak to average power ratio (PAPR) and bit error rate (BER) performance than the conventional OFDM, ZT DFT-S OFDM and ZT UW DFT-S OFDM systems. Daha fazlası Daha az

Ali ÖZEN

Bildiri | 2018 | IEEE 26th Signal Processing and Communications Applications SIU 2018 , pp.1 - 4

Bu bildiride, 5. nesil (5th Generation, 5G) dalga biçimi geliştirme çalışmalarına alternatif olarak sıfır sonlu ayrık Kosinüs dönüşümü yayılmalı OFDM (zero tail discrete cosine transform spread OFDM, ZT DCT-S OFDM) dalga biçimi önerilmektedir. Önerilen yöntemin başarımını doğrulamak ve klasik OFDM ile sıfır sonlu ayrık Fourier dönüşümü yayılmalı OFDM (ZT DFT-S OFDM) sistemleriyle karşılaştırmak için frekans seçici Rayleigh sönümlemeli kanallarda bilgisayar benzetimleri yapılmaktadır. Elde edilen benzetim sonuçları önerilen ZT DCT-S OFDM yönteminin klasik OFDM ve ZT DFT-S OFDM yönteminden daha iyi bant dışı yayılım (OOBE), tepe ortal . . .ama güç oranı (PAPR) ve bit hata oranı (BER) başarımlarına sahip olduğunu göstermektedir. In this paper, zero-tail discrete cosine transform spread OFDM (ZT DCT-S OFDM) waveform is proposed as an alternative to 5th generation (5G) waveform enhancement studies. In order to verify the performance of the proposed method and compare with the conventional OFDM and zero-tail discrete Fourier transform spread OFDM (ZT DFT-S OFDM) systems, computer simulations are performed on frequency selective Rayleigh fading channels. The obtained simulation results show that the proposed ZT DCT-S OFDM method has better out-of-band emission (OOBE), peak to average power ratio (PAPR) and bit error rate (BER) performance than conventional OFDM and ZT DFT-S OFDM. Daha fazlası Daha az

Ali ÖZEN

Bildiri | 2018 | IEEE 26th Signal Processing and Communications Applications SIU 2018 , pp.1 - 4

5G ve ötesi haberleşme sistemlerinin en kritik bileşenlerinden biri olan dalga şekli tasarımı, veri oranlarının yaklaşık 1000 kat artması, ultra düşük gecikme süresi, spektrum, enerji ve maliyet verimliliği gibi istekleri karşılamak için hayati bir rol oynamaktadır. Bu bildiride, 5. nesil (5th Generation, 5G) dalga şekli geliştirme çalışmalarına alternatif olarak sıfır sonlu ayrık dalgacık dönüşümü yayılmalı OFDM (zero-tail discrete wavelet transform spread OFDM, ZT DWT-S OFDM) dalga şekli önerilmektedir. Önerilen yöntemin başarımını doğrulamak ve klasik OFDM ile sıfır sonlu ayrık Fourier dönüşümü yayılmalı OFDM (ZT DFT-S OFDM) sist . . .emleriyle karşılaştırmak için AWGN ve düz sönümlemeli kanallarda bilgisayar benzetimleri yapılmıştır. Elde edilen benzetim sonuçları önerilen ZT DWT-S OFDM yönteminin; klasik OFDM ve ZT DFT-S OFDM yöntemlerinden daha iyi bant dışı yayılım (OOBE), tepe ortalama güç oranı (PAPR) ve bit hata oranı (BER) başarımlarına sahip olduğunu göstermiştir. Waveform design, which is one of the most critical components of 5G and beyond communication systems, plays a vital role in meeting the needs such as increasing data rates by about 1000 times, ultra-low latency, spectrum, energy and cost efficiency. In this paper, zero-tail discrete wavelet transform spread OFDM (ZT DWT-S OFDM) waveform is proposed as an alternative to 5th generation (5G) waveform enhancement studies. In order to verify the performance of the proposed method and compare with the conventional OFDM and zero-tail discrete Fourier transform spread OFDM (ZT DFT-S OFDM) systems, computer simulations were performed on AWGN and flat fading channels. The obtained simulation results show that the proposed ZT DWT-S OFDM method has better out-of-band emission (OOBE), peak to average power ratio (PAPR) and bit error rate (BER) performance than conventional OFDM and ZT DFT-S OFDM. Daha fazlası Daha az

Ali ÖZEN

Bildiri | 2017 | IEEE 40th International Conference on Telecommunications and Signal Processing, TSP 2017 , pp.190 - 194

A new approach based on discrete wavelet transform (DWT) and Walsh Hadamard transform (WHT) for improving carrier frequency offset (CFO) tracking performance of the multi carrier communication systems has been proposed in this paper. The proposed DWT-WHT technique has been applied to frequency domain channel equalizer (FDE) employed in orthogonal frequency division multiplexing (OFDM) systems. Computer simulations have been performed to verify the performance of the proposed method in stationary and nonstationary frequency selective Rayleigh fading channels. The obtained simulation results using HIPERLAN/2 (IEEE 802.11a) physical la . . .yer specifications have demonstrated that the proposed DWT-WHT-OFDM method is outperforming the CFO tracking performances of conventional OFDM, WHT-OFDM and DWT-OFDM techniques, and is removing the error floor Daha fazlası Daha az

Ali ÖZEN

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

Bu bildiride, çok taúÕyÕcÕlÕ haberleúme sistemlerinde kullanÕlan zaman bölgesi kanal denkleútiricilerin (Time Domain Equalizer, TDE) hata tabanÕ problemine bir çözüm bulmak için Walsh Hadamard Dönüúümü (Walsh Hadamard Transform, WHT) kullanÕlan ayrÕk dalgacÕk dönüúümü (Discrete Wavelet Transform, DWT) tabanlÕ yeni bir OFDM (DWT-WHT-OFDM) yöntemi önerilmektedir. Önerilen yöntemin baúarÕmÕnÕ göstermek için frekans seçici Rayleigh sönümlemeli kanallarda bilgisayar benzetimleri yapÕlmaktadÕr. HIPERLAN/2 (IEEE 802.11a) standardÕnÕ kullanarak elde edilen benzetim sonuçlarÕ önerilen DWT-WHT-OFDM yönteminin klasik OFDM, WHTOFDM ve DWT-OFDM . . .yöntemlerini geçerek hata tabanÕnÕ ortadan kaldÕrdÕ÷ÕnÕ göstermektedir. A Walsh Hadamard Transform (WHT) employed in discrete wavelet transform (DWT) based novel OFDM (DWTWHT-OFDM) method has been proposed as a solution to the problem of error floor of time domain channel equalizer (TDE) used in multi carrier communication systems in this paper. Computer simulations have been performed to show the performance of the proposed method in frequency selective Rayleigh fading channels. The obtained simulation results using HIPERLAN/2 (IEEE 802.11a) standard have demonstrated that the proposed DWT-WHT-OFDM method is outperforming conventional OFDM, WHT-OFDM and DWT-OFDM methods, and removing the error floor. Daha fazlası Daha az