https://jcis.sbrt.org.br/jcis/issue/feed Journal of Communication and Information Systems 2023-02-01T07:44:25-03:00 Lisandro Lovisolo jcis.editor@sbrt.org.br Open Journal Systems <p>The Journal of Communication and Information Systems (JCIS) features high-quality, peer-reviewed technical papers in several communications and information systems areas. The JCIS is jointly sponsored by the Brazilian Telecommunications Society (SBrT) and the IEEE Communications Society (ComSoc).&nbsp;</p> <p>There are no article publication or submission charges. Previous editions of the JCIS can be accessed <a href="/index.php/JCIS/issue/archive" target="_blank" rel="noopener">here</a>.</p> <p>This is an open-access journal which means that all content is freely available without charge to the user or his/her institution, permanently accessible online immediately upon assignment of the DOI. Users are allowed to read, download, copy, distribute, print, search, or link to the full texts of the articles or use them for any other lawful purpose without asking prior permission from the publisher or the author. This is under the BOAI definition of open access.</p> <p>ISSN: 1980-6604</p> https://jcis.sbrt.org.br/jcis/article/view/819 A New Ultraminiaturized Low-profile and Stable FSS with 2.5D Structure for 900 MHz ISM Band 2023-02-01T07:44:25-03:00 Mychael Jales Duarte mychael_duarte@hotmail.com Adaildo Gomes D'Assunção Júnior adaildojr@gmail.com Valdemir Praxedes da Silva Neto valdemir.praxedes@ufrn.br Adaildo Gomes d'Assunção adaildo@ymail.com <p class="Abstract"><span lang="EN-US">This paper presents a new 2.5D ultraminiaturized frequency selective surface (FSS) structure to operate in the 900 MHz ISM band (902 to 928 MHz), for application in the Wi-Fi HaLow. The proposed FSS simulation and design are performed using ANSYS HFSS software and equivalent circuit model (ECM). The development of the proposed 2.5D FSS is based on meander-line-based conducting patches and has required the simulation and design of typical (2D) and 2.5D structures. An equivalent circuit model was proposed and presented very accurate results. For comparison purpose, a prototype is fabricated and measured. Agreement is observed between simulation and measurement results.</span></p> 2023-02-01T07:44:25-03:00 ##submission.copyrightStatement## https://jcis.sbrt.org.br/jcis/article/view/814 Multilayer Framework for Resource Orchestration in Next Generation Networks 2023-01-16T11:37:27-03:00 Ermínio Ramos Paixão hermespaixao@gmail.com Diego Lisboa Cardoso, Dr. diego@ufpa.br Albert Einsten Santos albert.santos@itec.ufpa.br Daniel Silva Souza danielssouza@ufpa.br <div class="page" title="Page 1"> <div class="layoutArea"> <div class="column"> <p>Due to the significant increase in data traffic and the large number of Internet Protocol (IP) devices, operators and researchers are seeking solutions to address the greater demand. One of the most attractive of these is Heterogeneous Cloud Radio Access Networks (H-CRAN), which has the capacity to solve problems of the current generation and add several improvements, such as centralized processing and greater energy efficiency. However, resource orchestration such as radio, mapping between radio and BaseBand Unit (BBU) and load balance in BBU pool are still of the utmost importance. This paper proposes a multilayer approach that enables Peak Remote Radio Head (PRRH)-underutilized reconfiguration model and optimized mapping between PRRH and BBU, with the aim of achieving high availability, energy savings and a reduction in high-speed processing. Obtained results were compared with other approaches in the literature and showed that our model offers a more efficient means of mitigating the problems addressed in this paper.</p> </div> </div> </div> 2023-01-16T11:36:39-03:00 ##submission.copyrightStatement## https://jcis.sbrt.org.br/jcis/article/view/829 Index Encoding and Antenna Selection in Multiuser Precoder Index Modulation MIMO Communication 2022-11-11T09:27:28-03:00 Azucena Duarte azucenaduarte23@gmail.com João Alfredo Cal-Braz jabraz@inmetro.gov.br Raimundo Sampaio Neto raimundo@cetuc.puc-rio.br <p>Index modulation (IM) offers energy efficient solutions to communication systems by altering the on/off status of entities of the system. This work presents a multiuser (MU) IM-based system operating in a multiple-input multiple-output (MIMO) channel, named Multiuser Precoder Index Modulation (MU-PIM-MIMO), in which the choice of the IM-precoder matrices, responsible for assigning zero or nonzero values to the information vector, is a source of information. System model is specified for Zero-Forcing and Block Diagonalization channel precoders, as well as additional mechanisms, such as user notification and channel estimation. Numerical results show that MU-PIM-MIMO systems can offer attractive tradeoff between detection performance and spectral efficiency. Metrics for selection of the most favorable information bearing positions (IBP) patterns of the information vector, based on the maximization of the signal-to-noise ratio and on the maximization of the achievable rate, are developed in order to offer further improvements in system performance. Additionally, a scenario where the number of transmit antenna elements exceeds the number of radiofrequency chains at the base station is considered, and optimal and computational efficient ways to select the IBP patterns and the active transmit antennas are proposed. Simulation results evidence the effectiveness of the strategies.</p> 2022-11-11T09:27:28-03:00 ##submission.copyrightStatement## https://jcis.sbrt.org.br/jcis/article/view/818 On Generating Monte Carlo Simulations of Underwater Acoustic Communication Systems with Application to Transmit Beamforming 2022-11-03T16:33:29-03:00 Denis Backer de souza denis.backer@gmail.com Vinicius M. Pinho viniciusmesquita@poli.ufrj.br Rafael Chaves rafael.chaves@smt.ufrj.br Marcello L. R. Campos campos@smt.ufrj.br José A. Apolinário Jr. apolin@ime.eb.br <div class="page" title="Page 1"> <div class="layoutArea"> <div class="column"> <p>Underwater Acoustic (UWA) communication systems still rely heavily on at-sea trials. This work presents an operational framework that significantly reduces the need for practical experiments. The key idea is to generate channel impulse responses (CIRs) drawn from probability density functions constructed based on trusted information and to employ Monte Carlo simulations to develop new UWA communication systems. Hence, the proposed operational framework depends only on cheaper-to-acquire physical measurements to produce CIRs. It comprises a model-based CIR replay tool and a stochastic-based UWA channel simulator. The former can be any model-based CIR replay tool, and the latter is proposed in this work and validated using data from four different practical experiments. We also carried out experiments for a transmit beamforming with signals digitally modulated in binary phase-shift keying, which were transmitted by an array and by a single source with equivalent power. For the array, the ideal transmit direction comes from the lowest bit error rate (BER) obtained with computer simulations. This paper compares the performance of the transmit array to the single source transmission and the results of a practical experimental transmission with a Monte Carlo simulation employing the proposed technique. We show that both achieved close results regarding BER and mean squared error. The conclusion is that the proposed operational framework, once adjusted to the specific transmission site, can be used to design new UWA communication systems, eliminating the burden of at-sea trials for tests of new transceivers. Finally, we conducted real-life transmit beamforming experiments to verify the BER gain obtained in practice using the steering angle obtained from simulations.</p> </div> </div> </div> 2022-11-03T16:33:29-03:00 ##submission.copyrightStatement## https://jcis.sbrt.org.br/jcis/article/view/839 On the Information Content of Predictions in Word Analogy Tests 2022-10-18T12:05:21-03:00 Jugurta Montalvão jugurta.montalvao@gmail.com <pre>An approach is proposed to quantify, in bits of information, the actual relevance of analogies in analogy tests. The main component of this approach is a <em>soft</em> accuracy estimator that also yields entropy estimates with compensated biases. Experimental results obtained with pre-trained GloVe 300-D vectors and two public analogy test sets show that proximity hints are much more relevant than analogies in analogy tests, from an information content perspective. Accordingly, a simple word embedding model is used to predict that analogies carry about two bits of information, which is experimentally corroborated.</pre> 2022-10-18T12:02:53-03:00 ##submission.copyrightStatement## https://jcis.sbrt.org.br/jcis/article/view/833 Dual-band Polarization-independent Absorber Based on Resistive Frequency Selective Surface 2022-10-05T15:37:34-03:00 Anamaria Sena Maia anamaria_sena@hotmail.com Antônio Luiz Pereira de Siqueira Campos alpscampos@gmail.com Maurício Weber Benjó da Silva mauricio.weber@gmail.com Ruann Víctor de Andrade Lira ruannvictor@gmail.com Alfredo Gomes Neto alfredogomesjpa@gmail.com <p>In this paper, a three-layered frequency-selective absorber (FSA) that can efficiently absorb electromagnetic waves (EM) in a double-band is proposed. The proposed structure is designed so that signals reflected from the frequency selective ground plane are located at 2.4 and 5.5 GHz (ISM and UNII bands) and absorbed by the front resistive layers. Simulation results show that the proposed absorber not only blocks transmission in the desired bands but absorbs the signals reflected from the conductive layer. Reflective FSS unit cells are composed of double square loops printed on an FR-4 substrate and the resistive layers are formed of OhmegaPly material with a resistivity of 50 ohms per square. Furthermore, the proposed absorber is 0.17λ thick at the lowest frequency of absorption. The experimental results agree with the numerical simulations and show an absorptivity of more than 90% at 2.4 and 5.5 GHz, covering entirely ISM and UNII bands.</p> 2022-10-05T15:37:34-03:00 ##submission.copyrightStatement## https://jcis.sbrt.org.br/jcis/article/view/812 Empirical Mode Decomposition: Theory and Applications in Underwater Acoustics 2022-08-22T08:59:26-03:00 Elio Pithon Sarno Filho elio.pithon@ufba.br Anderson Damacena Santos anderson.damacena@ufba.br Henrique Moura Sinezio henriquedemourasinezio@gmail.com Eduardo Furtado Simas Filho eduardo.simas@ufba.br Antônio Carlos Lopes Fernandes Jr antonio.lopes@ufba.br José Manoel de Seixas seixas@lps.ufrj.br <p>Empirical mode decomposition (EMD) is a signal processing method that produces a data-driven time-frequency representation suited to characterize time-varying and nonlinear phenomena. In EMD, intrinsic mode functions (IMF) are sequentially estimated from the signal of interest to represent different intrinsic oscilation modes and produce an orthogonal representation of the original information. Different algorithms have been proposed for EMD estimation to deal with limitations such as mode-mixing and noise sensitivity. To obtain a frequency-domain representation, EMD is usually associated with the Hilbert transform, in this case, the method is referred to as the Hilbert-Huang transform (HHT). This paper presents a theoretical review of the fundamental aspects of both EMD and HHT, such as IMF estimation procedure and IMF orthogonality. Variations of the original EMD algorithm are also presented. Both simulated and experimental underwater acoustic signals are used to illustrate the efficiency of EMD/HHT in revealing relevant characteristics from time-varying and nonlinear information.</p> 2022-08-22T08:59:26-03:00 ##submission.copyrightStatement## https://jcis.sbrt.org.br/jcis/article/view/755 On Symmetric Channels and Codes Over the Quaternion Group 2022-07-26T15:37:46-03:00 Jorge P Arpasi arpasi@gmail.com <p>In this paper we study symmetric channels and group codes over the quaternion group Q<sub>8</sub>.&nbsp;We show that, related to these channels, there is the number C<sub>Q8</sub><sub>,</sub> called group-capacity,&nbsp;which is less or equal than the capacity of the channel. Also we show that C<sub>Q8&nbsp;</sub>is an upper bound for the rate of any reliable quaternion group code. Finally we show&nbsp;that the group-capacity equals the channel capacity.</p> 2022-07-26T15:37:46-03:00 ##submission.copyrightStatement## https://jcis.sbrt.org.br/jcis/article/view/823 Performances of 2r16APSK and DVB-S2 16APSK Modulations over a Two-Link Satellite Channel 2022-07-20T13:49:17-03:00 Dayan Adionel Guimarães dayan@inatel.br <p>In this paper, the 2r16APSK modulation is contrasted&nbsp;with the 16APSK modulation adopted in the digital&nbsp;video broadcast standard, the DVB-S2, aiming at verifying if&nbsp;the 2r16APSK can be considered an alternative choice for the&nbsp;DVB-S2 and other alike communication systems when subjected&nbsp;to nonlinear distortions. To this end, the performances of both&nbsp;modulations are assessed in terms of the metrics: bit error&nbsp;rate (BER), constellation figure of merit (CFM), peak-to-average&nbsp;power ratio (PAPR), total degradation (TD) versus input back-off&nbsp;(IBO), and spectral regrowth, when the transmitted signal goes&nbsp;through a two-link satellite channel under memoryless nonlinear&nbsp;distortion produced by a traveling wave tube amplifier (TWTA),&nbsp;which is described by the Saleh model. The results show that the&nbsp;2r16APSK modulation is indeed an alternative choice.</p> 2022-07-20T13:49:17-03:00 ##submission.copyrightStatement## https://jcis.sbrt.org.br/jcis/article/view/817 Resource Allocation for Maximizing Spectral Efficiency in a Multiuser MFSK System 2022-07-06T10:03:36-03:00 Manish Sharma manish@ita.br Daniel Basso Ferreira danielbf@ita.br <p>In this paper we explore strategies to improve spectral efficiency values of a multiuser M-ary Frequency Shift Keying (MFSK) system when a fast and frequency selective fading channel with limited bandwidth is available and $L$ receiving antennas are present at the base station. Two options are considered: bandwidth splitting and cell splitting, where random user distribution and the effects of antenna directivity on signal to noise ratio was considered. Results show that in this situation the best case scenario is the one in which all users share the whole bandwidth instead of splitting it. Also, given the limitation on available antennas and radio frequency receiver chains at the base station, it is better to split cell antennas into as many sectors as possible, even at the cost of losing spatial diversity in each sector. Given the constraints, sectoring allows the system to reach values of spectral and energy efficiencies unachievable by spatial diversity by itself.</p> 2022-07-06T10:03:36-03:00 ##submission.copyrightStatement##