7,029 research outputs found
Paleontological evidence of Paleogene transgression on Adriatic carbonate platform
No full textCosovic V., Aloncic D.B., Koic M., Marjanac T., Moro A., Gusic Ivan, Jelaska Vladimir. Paleontological evidence of Paleogene transgression on Adriatic carbonate platform. In: Géologie Méditerranéenne. Tome 21, numéro 3-4, 1994. Perimediterranean carbonate platforms. First International Meeting. Marseille – France (5-8 septembre 1994) sous la direction de Jean-Pierre Masse. pp. 49-53
The Upper Cretaceous geodynamic evolution of the Adriatic-Dinaric carbonate platform(s)
No full textJelaska Vladimir, Gusic Ivan, Jurkovšek Bogdan, Ogorelec Bojan, Cosovic V., Sribar L., Toman M. The Upper Cretaceous geodynamic evolution of the Adriatic-Dinaric carbonate platform(s). In: Géologie Méditerranéenne. Tome 21, numéro 3-4, 1994. Perimediterranean carbonate platforms. First International Meeting. Marseille – France (5-8 septembre 1994) sous la direction de Jean-Pierre Masse. pp. 89-91
OFDM synchronization in an uncoordinated spectrum sharing scenario
No full textIn this paper synchronization of uncoordinated OFDM spectrum sharing systems that operate in the presence of narrowband interference (NBI) is analyzed. Conventional synchronization algorithms based on correlation of synchronization preamble in time domain suffer from considerable performance degradation when NBI is present. To overcome this degradation we propose and analyze a method to detect NBI presence and to suppress its influence on synchronization before estimation of synchronization parameters is performed at the OFDM receiver. We focus on an OFDM WLAN system operating in license-exempt band and analyze synchronization performance when NBI is active. The proposed method does not introduce any additional preamble overhead with respect to existing WLAN preamble and requires only slightly higher computational complexity at the receiver. To illustrate effectiveness of the proposed method, several numerical examples are provided
Channel Estimation for MC-CDMA Uplink Transmissions with Combined Equalization
No full textCombined equalization has recently been proposed to enhance the error rate performance of conventional multicarrier code-division multiple-access (MC-CDMA) systems. This technique applies pre-equalization at the transmitter in conjunction with post-equalization at the receiver, thereby splitting the overall equalization process into two separate parts. In this way, efficient power allocation over the available subcarriers is possible at the transmitter, while leaving the interference cancellation task at the receiver. In this paper, we consider the uplink of an MC-CDMA system employing combined equalization. As the users transmit from different locations, the uplink signals arrive at the base station after passing through different multipath channels and the goal is to estimate the pre-equalized channel frequency response of each user. This is pursued following two different approaches. The first operates in the frequency-domain and treats the channel gains over adjacent subcarriers as independent unknown parameters. The second operates in the time-domain and achieves better performance by reducing the number of unknown parameters. Both schemes are based on maximum-likelihood reasoning and require knowledge of the transmitted symbols. Numerical examples are given to highlight the effectiveness of the proposed methods
On the Performance of Cancellation Carrier-Based Schemes for Sidelobe Suppression in OFDM Networks
No full textAn efficient scheme for limiting the inherent high out-of-band radiation of the orthogonal frequency-division multiplexing signal has been studied by Brandes el al.. The scheme achieves sidelobe suppression by using few subcarriers, referred to as cancellation carriers (CCs), positioned at the edges of the spectrum and modulated by data-dependent complex-valued symbols that are designed so as to minimize the out-of-band radiation. Unfortunately, its performance has been investigated at the input of the power amplifier (PA) without considering the spectral re-growth induced by PA's non-linear region. Motivated by the above consideration, in this work we return to the aforementioned scheme and investigate its performance at the output of the PA. In addition, since reducing the time-domain signal peaks may alleviate the problem of spectral re-growth, we also adopt two well-known tone reservation (TR)-based peak reduction algorithms
Yuriy Hryvniak as a researcher of the biography of Ivan Puluj
No full textМатеріал тез присвячено дослідженню сторінок біографії
Юрія Гривняка - автора монографії про Івана Пулюя, яку було
опубліковано 1971 року у Лондоні завдяки фінансовій підтримці Союзу
українців у Великій Британії. Автором було використано ряд фото та
архівних матеріалів, отриманих від О. Пулюя. На жаль, творчість і
життєвий шлях Ю. Гривняка є маловідомими в Україні, а доля зібраних
ним джерел потребує фахового дослідженняThese theses are devoted to the study of the pages of Yuriy
Hryvniak’s biography. He was the author of a monograph dedicated to the study
of the life and activities of the famous Ukrainian scientist and public figure Ivan
Puluj. The author used a number of photos and archival materials received from
O. Puluj. Unfortunately, the creativity and life path of Y. Hryvniak is little
known in Ukraine, and the fate of the sources collected by him requires
professional researc
Physical Layer Design for a Broadband Overlay System for ATC Communications in the VHF Band
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