Wyniki wyszukiwania - BazTech

1

Fading Channel Prediction for 5G and 6G Mobile Communication Systems

Soszka Maciej

International Journal of Electronics and Telecommunications

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2022

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Vol. 68, No. 1

153--160

EN

Nowadays, there is a trend to employ adaptive solutions in mobile communication. The adaptive transmission systems seem to answer the need for highly reliable communication that serves high data rates. For efficient adaptive transmission, the future Channel State Information (CSI) has to be known. The various prediction methods can be applied to estimate the future CSI. However, each method has its bottlenecks. The task is even more challenging while considering the future 5G/6G communication where the employment of sub-6 GHz and millimetre waves (mmWaves) in narrow-band, wide-band and ultra-wide-band transmission is considered. Thus, author describes the differences between sub-6 GHz/mmWave and narrow-band/wide-band/ultra-wide-band channel prediction, provide a comprehensive overview of available prediction methods, discuss its performance and analyse the opportunity to use them in sub-6 GHz and mmWave systems. We select Long Short-Term Memory Recurrent Neural Network (RNN) as the most promising technique for future CSI prediction and propose optimising two of its parameters - the number of input features, which was not yet considered as an opportunity to improve the performance of CSI prediction, and the number of hidden layers.

2

Analysing the impact on underwater noise of changes to the parameters of a ship’s machinery

Buszman Krystian

Polish Maritime Research

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2020

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nr 3

176--181

EN

A ship moving over the surface of water generates disturbances that are perceived as noise, both in the air and under water. Due to its density, water is an excellent medium for transmitting acoustic waves over long distances. This article describes the impact of the settings of a ship’s machinery on the nature of the generated noise. Our analysis includes the frequency characteristics of the noise generated by the moving ship. Data were obtained using an underwater measurement system, and the measured objects were two ships moving on specific trajectories with certain machinery settings. The acquired data were analysed in the frequency domain to explore the possibilities of the acoustic classification of ships and diagnostics of source mechanisms.

3

Lorentzian Operator for Angular Source Localization with Large Array

Khmou Y., Safi S., Frikel M.

Journal of Telecommunications and Information Technology

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2015

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nr 4

98--105

EN

Source localization problem consists of an ensemble of techniques that are used to obtain spatial information of present radiation in given medium of propagation, with a constraint of the antenna geometry and the characteristics of radiating sources. This condition gives multitude of cases to study, hence several methods were proposed in the literature. In this paper, a new algorithm for estimating the Direction of Arrival (DoA) of narrowband and far eld punctual sources is introduced. By exploiting the spectrum of covariance matrix of received data, the Lorentzian function on spectral matrix to lter the eigenvalues is applied. This ltering process eliminates the eigenvalues belonging to signal subspace. Parameters of Lorentz function are adjusted using rst and second statistics of eigenvalues. The algorithm requires the knowledge of minimum eigenvalue and is performing when the dimension of antenna is relatively large which is conrmed by several Monte Carlo simulations.

4

Transmission characteristics of 85Rb and 87Rb laser-induced dichroism atomic filters at 795 nm

Peng Y F, Zhang W J

Optica Applicata

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2014

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Vol. 44, nr 1

55--67

EN

The transmission characteristics for 85Rb and 87Rb laser-induced dichroism atomic filters operating on rubidium D1 lines (795 nm) transitions are analyzed. By means of semiclassical density matrix equations of motion, a three-level model for the transmission characteristics of the ground state laser-induced dichroism atomic filter is presented. Calculative results show that this filter, using two counterpropagating pump and probe beams, can obtain higher transmission, narrower bandwidth and larger tuning capability than that using two copropagating pump and probe beams; with the aid of counterpropagating pump, the 85Rb ground state laser-induced dichroism atomic filter can be more effective to achieve higher peak transmission (>34%) and larger tunability (>1 GHz) than the 87Rb ground state laser-induced dichroism atomic filter in the same operation parameters. This result may be helpful for improving peak transmission (14.6%) of Rb ground state laser-induced dichroism atomic filter reported (CERÈ A. et al., Opt. Lett. 34(7), 2009, pp. 1012–1014).

5

Suppression method of partial-discharge interference signal based on the combination of morphological filters and complex wavelet transform

Wang Y., Zhang D., Lu G., Huang Y.

Przegląd Elektrotechniczny

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2013

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R. 89, nr 4

123-128

EN

Solving the periodic narrowband interference and suppression of white noise during the actual detection of partial discharge (PD) are difficult. In this paper, a method of suppressing the interference signal method based on the combination of morphological filters and complex wavelet transform is proposed. Generalized morphological filters based on the principle of mathematical morphology were structured and set as a pre-filter unit to realize pre-treatment of the original PD signals, and complex wavelet transform was then employed to process the PD signals. Finally, denoised PD signals were obtained. Applying this method to deal with the noise in the simulation and acquisition of PD signals, the results showed that the method can restrain effectively the PD periodic narrowband interference and white noise. Compared with the same wavelet base of the wavelet and the complex wavelet denoising methods, this method reduces energy loss and retains well the PD signals characteristics.

PL

W artykule opisano metodę tłumienia zakłóceń (zakłócenia wąskopasmowe, biały szum) w sygnałach, w przypadku wykrycia wyładowań niezupełnych. W rozwiązaniu wykorzystano kombinację filtrów morfologicznych, działających jako pre-filtr i złożoną transformatę falkową do dalszej obróbki sygnałów. Wykonano badania symulacyjne, potwierdzające skuteczność filtracji.

6

Przyszłość rynku PMR/PAMR

Kwolek J., Wroński J.

Przegląd Telekomunikacyjny + Wiadomości Telekomunikacyjne

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2006

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nr 4

119-22

PL

Przedstawiono trendy techniczne rozwoju rynku PMR/PAMR, związane z implementacją cyfrowych systemów: wąskopasmowych o paśmie rozszerzonym i szerokopasmowych. Omówiono kwestie związane z zagospodarowaniem widma, wskazano zakresy częstotliwości, jakie można będzie przeznaczyć dla potrzeb powyższych systemów.

EN

This article describes the new technology trends on PMR/PAMR market, connected with digital implementation for narrow, wide-and broad-band high speed systems. Compatibility with existing systems and spectrum management for new one has been presented. The frequency bands for the new systems have been shown.