2018. 4th Issue

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GUEST EDITORIAL

Eszter Udvary
Selected papers of the CSNDSP 2018 conference  
The 11th IEEE, IET International Symposium on Communication Systems, Networks, and Digital Signal Processing (CSNDSP) was hosted by The Faculty of Electrical Engineering and Informatics at Budapest University of Technology and Economics, Hungary, 18-20 July 2018. Detailed information can be found on its website (http://csndsp2018.com/).

PAPERS OF THE SPECIAL ISSUE

Tongyang Xu, Hedaia Ghannam and Izzat Darwazeh
Practical Evaluations of SEFDM: Timing Offset and Multipath Impairments  
The non-orthogonal signal waveform spectrally efficient frequency division multiplexing (SEFDM) improves spectral efficiency at the cost of self-created inter carrier interference (ICI). As the orthogonal property, similar to orthogonal frequency division multiplexing (OFDM), no longer exists, the robustness of SEFDM in realistic wireless environments might be weakened. This work aims to evaluate the sensitivity of SEFDM to practical channel distortions using a professional experiment testbed. First, timing offset is studied in a bypass channel to locate the imperfection of the testbed and its impact on SEFDM signals. Then, the joint effect of a multipath frequency selective channel and additive white Gaussian noise (AWGN) is investigated in the testbed. Through practical experiments, we demonstrate the performance of SEFDM in realistic radio frequency (RF) environments and verify two compensation methods for SEFDM. Our results show first frequency-domain compensation works well in frequency non-selective channel conditions while time-domain compensation method is suitable for frequency selective channel conditions. This work paves the way for the application of SEFDM in different channel scenarios.

Husam Al-Amaireh and Zsolt Kollár
Overview and Complexity Evaluation of FBMC Transmitter Architectures  
Computational complexity is one of the key factors considered for evaluating transmitter performance of future 5G applications. In this contribution we have chosen Filter Bank MultiCarrier (FBMC) as it is the most possible candidate to replace/coexist with the Orthogonal Frequency Division Multiplexing (OFDM) modulation. In the literature two main design approaches can be found for FBMC: Frequency Spreading (FS) and PolyPhase Network (PPN). From these two structures numerous schemes were derived. These schemes are studied and the complexity (real multiplications and additions) for each scheme is compared. Based on the complexity calculations, the simulation results show that PPN has a better complexity performance compared with FS. Also, the alternative PPN schemes have significant improvement in complexity compared to the standard PPN.

Róbert Horváth, Jean-François Roux, Julien Poëtte and Béatrice Cabon
Optoelectronic mixer with a photoconductive switch for 1550 nm wavelengths  
We demonstrate an optoelectronic mixer based on an ultrafast InGaAs photoconductive switch and its use in an innovative heterodyne detection system for Radio over Fibre transmission. The advantage of the proposed switch is its relatively flat response curve in a wide frequency range up to 67 GHz. Two mixing schemes are presented through I-Q modulated data-stream down-conversion. The data can modulate either the electrical signal or the optical signal. In case the electrical signal is modulated, a mode-locked semiconductor laser diode is used as an optical local oscillator at the self-oscillating frequency of 24.5 GHz. The InP based quantum-dash mode-locked laser emitting in the 1570 nm wavelength range is stabilized by a feedback loop and shows a low phase noise in order to increase the mixing performances of the detection apparatus. In a second experiment, the photoconductive switch is combined with a continuous wave laser to demonstrate the feasibility of down converting an optically provided data-stream with an electrical local oscillator.
 
Yahiea Al Naiemy, Taha Elwi, Lajos Nagy and Thomas Zwick
A Systematic Analysis and Design of a High Gain Microstrip Antenna based on a Single EBG Layer  
In this paper, an Electromagnetic Band Gap (EBG) lens of a single layer is invented to improve the gain of a truncated slotted square patch antenna for the Wi-Fi applications. The proposed EBG lens is structured from 55 planar array. The individual unit cell is basically shaped as a couple of a split concave conductive patch. The proposed EBG struc- ture performance is tested numerically using Finite Integration Technique (FIT) formulations of CSTMWS and analytically using circuit theory. Then, the antenna performance in terms of |S11|, the boresight gain, and radiation patterns are reported and compared to the performance before introducing the EBG lens to identify the significant enhancements. The proposed EBG antenna is simulated numerically inside FIT formulations of CSTMWS time domain (TD) solver. A significant gain enhancement of 11.1 dBi at 2.45 GHz and a front to back ratio (F/B) about 22 dB are achieved after introducing the EBG lens. The antenna performance is validated using a frequency domain (FD) solver based CSTMWS formulations to obtain excellent agreements between the two invoked methods.
 
Balázs Matolcsy and Attila Zólomy
Overcoming the Realization Problems of Wideband Matching Circuits  
During the analytical design process of wideband impedance matching major problems may arise, that might lead to non-realizable matching networks, preventing the successful impedance matching. In this paper two practical design rules and a simplified equation is presented, supporting the design of physically realizable impedance matching networks. The design rules and calculation technique introduced by this paper is summarized, and validated by microwave circuit simulation examples.
 
József Varga, Attila Hilt, József Bíró, Csaba Rotter and Gábor Járó

Reducing operational costs of ultra-reliable low latency services in 5G  
Ultra-reliable low latency (uRLL) communication in 5G dictates the deployment of distributed infrastructure with numerous datacenters for low latency, while hosting ultra-reliable services mandates attended datacenters. This would boost the operational costs of 5G network operators planning country-wide coverage for uRLL services. This paper examines how these operational expenses dominated by administrative costs can be reduced without impacting the quality of the provided uRLL service. Our results indicate that hosting uRLL services in unattended datacenters with increased hardware redundancy schemes can produce significant cost savings.

 

CALL FOR PAPERS / PARTICIPATION

Central European Conference on Cryptology
CECC 2019, Telc, Czech Republic

42nd International Conference on Telecommunications and Signal Processing (TSP)
TSP 2019, Budapest, Hungary

28th European Conference on Networks and Communications
EuCNC 2019, Valencia, Spain

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2018. 3rd Issue

Table of contents 

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GUEST EDITORIAL minta

László Bacsárdi and Kálmán Kovács
Featured papers of the H-SPACE 2018 conference  
In 2018, the annual International Conference on Research, Technology and Education of Space has been held the 4th time. The host was the BME Space Forum operated by the Federated Innovation and Knowledge Centre (EIT) of the Faculty of Electrical Engineering and Informatics at the Budapest University of Technology and Economics (BME) – in cooperation with the Hungarian Astronautical Society (MANT), which is the oldest space association in Hungary. Three selected papers are featured in the current issue of the Infocommunications Journal.

PAPERS OF THE SPECIAL ISSUE

Bernard Adjei-Frimpong and László Csurgai-Horváth
Using Radio Wave Satellite Propagation Measurements for Rain Intensity Estimation  
The European Space Agency launched a communication satellite called Alphasat in 2013, with two experimental beacons to carry out a scientific experiment by measurement at frequencies of 19.7 GHz and 39.4 GHz respectively. Propagation through the atmosphere at these frequencies is affected by the resence of atmospheric gases and other particles like water vapour, rain and ice drops. Rain attenuation is the most significant parameter which degrades the performance of the links by absorbing and scattering radio waves that can be determined as the measured received signal power’s deviation from the nominal, non-attenuated level. Rainfall statistical data are also measured and recorded by the propagation terminals to provide additional information to apply prediction methods that require minutes of integration time rain intensity.

Andrea Farkasvölgyi and István Frigyes
Optical transfer in space communication  
This paper presents the possibilities of Free-space optical connection (FSO) in space communication in case of satellite-to-spacecraft or satellite-to-satellite link. It summerizes the advantages and disadvantages of optical transmissions in case of near-earth and deep space region. We present the most significant problems during FSO link application and introduce some techniques to eliminate the drawbacks. In this paper, we introduce the use of multi-channel FSO system, which is the most appropriate in order to maximize channel parameters with minimizing the transmission error. It compares available maximum channel parameters of near future space missions. Under special conditions in satellite-earth connection, the usage of the optical link may become very uncertain, because of the strong turbulent medium. We describe conditions under which the optical link can be applied in satellite communication and when it is necessary to effectively modify the optical connection, This article discusses the application of multichannel or more precise diversity systems, which we recommend for space communication.

Máté Galambos and László Bacsárdi
Comparing Calculated and Measured Losses in a Satellite-Earth Quantum Channel  
Long distance distribution of quantum states is necessary for quantum communication and large scale quantum experiments. Currently this distance is limited by channel loss. Previous theoretical analisys and proof of concept experiments showed that satellite quantum communication may have lower losses than optical cable based counterparts. Recently the QuESS experiment [3] realized the first satellite-Earth quantum channel. In this paper we compare  heoretical predictions of different mathematical models with experimental results regarding channel loss. We examine the HV-5/7 model, HV-Night model and Greenwood model of optical turbulences, the geometric [4] and diffraction [5][6] models of beam wander and beam widening. Furthermore we take into account the effect of atmospheric gases and aerosols as well as the effect of pointing error. We find that theoretical predictions are largely in the same order of magnitude as experimental results. The exception is the diffraction model of beam spreading where our calculations yielded only one tenth of the measured value. Given the ever changing nature of weather conditions and the changing composition of atmospheric aerosoles we conclude that calculated and measured losses are in good agreement.

PAPERS FROM OPEN CALL

Dániel Péter Kun, Erika Baksáné Varga and Zsolt Tóth
Ontology based Indoor Navigation Service for the ILONA System  
An ontology based way finding algorithm is presented in this paper that allows route generation between two separate parts of an indoor environment. The presented ontology provides a flexible way to describe and model the indoor environment, in addition it fits and extends the existing model of the ILONA System. Ontology reasoners provide an efficient way to perform complex queries over the knowledge base. The instances, that are queried by the reasoner, are used to initialize the graph which represents an indoor environment. Due to parameterization of the reasoner, different graphs can be generated from the ontology which makes the way finding algorithm flexible. Thus, the task of indoor way finding was converted into a well-known graph search problem. Dijkstra’s shortest path algorithm is used for route generation in the graph yielded. The algorithm was implemented and tested in the ILONA System and its functioning is demonstrated by real-life scenarios.

Miklós Gábriel Tulics and Klára Vicsi
Automatic classification possibilities of the voices of children with dysphonia  
Dysphonia is a common complaint, almost every fourth child produces a pathological voice. A mobile based filtering system, that can be used by pre-school workers in order to recognize dysphonic voiced children in order to get professional help as soon as possible, would be desired. The goal of this research is to identify acoustic parameters that are able to distinguish healthy voices of children from those with dysphonia voices of children. In addition, the possibility of automatic classification is children. In addition, the possibility of automatic classification is examined. Two sample T-tests were used for statistical significance testing for the mean values of the acoustic parameters between healthy voices and those with dysphonia. A two-class classification was performed between the two groups using leave-one-out cross validation, with support vector machine (SVM) classifier. Formant frequencies, mel-frequency cepstral coefficients (MFCCs), Harmonics-to-Noise Ratio (HNR), Soft Phonation Index (SPI) and frequency band energy ratios, based on intrinsic mode functions measured on different variations of phonemes showed statistical difference between the groups. A high classification accuracy of 93% was achieved by SVM with linear and rbf kernel using only 8 acoustic parameters. Additional data is needed to build a more general model, but this research can be a reference point in the classification of voices using continuous speech between healthy children and children with dysphonia. 

CALL FOR PAPERS / PARTICIPATION

IEEE Global Communications Conference
IEEE GLOBECOM 2019, Hawaii, USA

4th IEEE/IFIP International Workshop on Analytics for Network and Service Management
AnNet 2019, Washington DC, USA 

IEEE Eurocon Conference
IEEE EUROCON 2019, Novi Sad, Serbia

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