Journal of Communication and Information Systems <p>The Journal of Communication and Information Systems (JCIS) features high-quality, peer-reviewed technical papers in several areas of communications and information systems. The JCIS is jointly sponsored by the Brazilian Telecommunications Society (SBrT) and the IEEE Communications Society (ComSoc). As from March 2018, Prof. Richard Demo Souza from Federal University of Santa Catarina (Brazil) and Prof. Glauber Brante from Federal University of Technology - Paraná (Brazil) are the Editors-in-Chief of the JCIS.&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 in accordance with the BOAI definition of open access.</p> <p>ISSN: 1980-6604</p> Brazilian Telecommunications Society en-US Journal of Communication and Information Systems 1980-6604 <p><span>Authors who publish with this journal agree to the following terms:</span><br /><br /></p><ol type="a"><ol type="a"><li>Authors retain copyright and grant the journal right of first publication with the work simultaneously licensed under a <a href="" target="_new">Creative Commons Attribution License</a> that allows others to share the work with an acknowledgement of the work's authorship and initial publication in this journal.</li></ol></ol><p> </p><ol type="a"><ol type="a"><li>Authors are able to enter into separate, additional contractual arrangements for the non-exclusive distribution of the journal's published version of the work (e.g., post it to an institutional repository or publish it in a book), with an acknowledgement of its initial publication in this journal.</li></ol></ol><p> </p><ol type="a"><ol type="a"><li>Authors are permitted and encouraged to post their work online (e.g., in institutional repositories or on their website) prior to and during the submission process, as it can lead to productive exchanges, as well as earlier and greater citation of published work (See <a href="" target="_new">The Effect of Open Access</a>).</li></ol></ol><p>___________</p> Receivers for the uplink of multiuser generalized spatial modulation MIMO systems <p><span class="fontstyle0">Generalized spatial modulation is envisioned as a promising communication paradigm for the next communication systems, in which high data rates and reliability are important features, but also energy and infrastructure-saving solutions are seeked. This work presents a variety of efficient suboptimal signal detection strategies for the uplink of multiuser GSM MIMO systems. They are comprised of user decoupling strategies followed by GSM signal detection schemes, and offer different balances of detection performance and computational complexity. Simulation results exhibit the performance of these strategies under different system scenarios and channel propagation effects.</span> </p> José Calpa João Alfredo Cal-Braz Rodrigo David Raimundo Sampaio-Neto ##submission.copyrightStatement## 2020-05-31 2020-05-31 35 1 133 137 10.14209/jcis.2020.14 SDMA Grouping Based on Unsupervised Learning for Multi-User MIMO Systems <p>In this study, we investigate a spatial division multiple access (SDMA) grouping scheme to maximize the total data rate of a multi-user multiple input multiple output (MU-MIMO) system. Initially, we partition the set of mobile stations (MSs) into subsets according to their spatial compatibility. We explore different clustering algorithms, comparing them in terms of computational complexity and capability to partition MSs properly. Since we consider a scenario with a massive arrange of antenna elements and that operates on the mmWave scenario, we employ a hybrid beamforming scheme and analyze its behavior in terms of the total data rate. The analog and digital precoders exploit the channel information obtained from clustering and scheduling, respectively.&nbsp; The simulation results indicate that a proper partition of MSs into clusters can take advantage of the spatial compatibility effectively and reduce the multi-user (MU) interference. The hierarchical clustering (HC) enhances the total data rate 25% compared with the baseline approach, while the density-based spatial clustering of applications with noise (DBSCAN) increases the total data rate 20%.</p> Francisco Hugo Costa Neto Tarcisio Ferreira Maciel ##submission.copyrightStatement## 2020-05-29 2020-05-29 35 1 124 132 10.14209/jcis.2020.13 A Cepstral Method to Estimate the Stable Optimal Solution for Feedforward Occlusion Cancellation in Hearing Aids <p>The occlusion effect is a common complaint from&nbsp;users of hearing aids with narrow or unvented earmolds. This&nbsp;phenomenon makes the user hear his own voice muffled. In the&nbsp;scientific literature, fixed and adaptive controllers have been&nbsp;proposed for occlusion effect reduction. This work proposes&nbsp;a cepstral method to estimate the stable optimal solution for&nbsp;feedforward occlusion cancellation and a fixed controller that&nbsp;utilizes this estimate to reduce the occlusion effect in hearing&nbsp;aids. The cepstral method operates on a feedback structure at a&nbsp;calibration process. Simulations have shown that the performance&nbsp;of the cepstral method improves as the length of the signal uttered&nbsp;by the hearing aid user increases, resulting in estimates with&nbsp;average normalized misalignment less than -19 and -34 dB for&nbsp;signals lasting 1.5 and 5 s. The estimates are significantly more&nbsp;accurate below 500 Hz, which is the frequency range common to&nbsp;the occlusion effect. In addition, results have pointed out that the&nbsp;controller attenuated the occlusion effect, averagely decreasing by&nbsp;0.17 dB the distortion power and increasing by 0.13 the objective&nbsp;perceptual quality MOS-LQO score.</p> Bruno Catarino Bispo Renata Coelho Borges ##submission.copyrightStatement## 2020-05-23 2020-05-23 35 1 113 123 10.14209/jcis.2020.12 Multichannel Source Separation Using Time-Deconvolutive CNMF <p><span style="left: 110.981px; top: 219.639px; font-size: 11.0761px; font-family: sans-serif; transform: scaleX(0.843704);">This paper addresses the separation of audio sources</span><span style="left: 60.4849px; top: 231.946px; font-size: 11.0761px; font-family: sans-serif; transform: scaleX(0.885248);">from convolutive mixtures captured by a microphone array. We</span><span style="left: 60.4849px; top: 244.252px; font-size: 11.0761px; font-family: sans-serif; transform: scaleX(0.851621);">approach the problem using complex-valued non-negative matrix</span><span class="" style="left: 60.4849px; top: 256.56px; font-size: 11.0761px; font-family: sans-serif; transform: scaleX(0.858616);">factorization (CNMF), and extend previous works by tailoring</span><span style="left: 60.4849px; top: 268.867px; font-size: 11.0761px; font-family: sans-serif; transform: scaleX(0.836988);">advanced (single-channel) NMF models, such as the deconvolutive</span><span class="" style="left: 60.4849px; top: 281.173px; font-size: 11.0761px; font-family: sans-serif; transform: scaleX(0.863316);">NMF, to the multichannel factorization setup. Further, a sparsity-</span><span style="left: 60.4849px; top: 293.48px; font-size: 11.0761px; font-family: sans-serif; transform: scaleX(0.804771);">promoting scheme is proposed so that the underlying estimated</span><span style="left: 60.4849px; top: 305.787px; font-size: 11.0761px; font-family: sans-serif; transform: scaleX(0.819299);">parameters better fit the time-frequency properties inherent</span><span style="left: 60.4849px; top: 318.093px; font-size: 11.0761px; font-family: sans-serif; transform: scaleX(0.815457);">in some audio sources. The proposed parameter estimation</span><span style="left: 60.4849px; top: 330.401px; font-size: 11.0761px; font-family: sans-serif; transform: scaleX(0.854986);">framework is compatible with previous related works, and can be</span><span class="" style="left: 60.4849px; top: 342.708px; font-size: 11.0761px; font-family: sans-serif; transform: scaleX(0.85244);">thought of as a step toward a more general method. We evaluate</span><span style="left: 60.4849px; top: 355.014px; font-size: 11.0761px; font-family: sans-serif; transform: scaleX(0.856324);">the resulting separation accuracy using a simulated acoustic</span><span style="left: 60.4849px; top: 367.321px; font-size: 11.0761px; font-family: sans-serif; transform: scaleX(0.860362);">scenario, and the tests confirm that the proposed algorithm</span><span class="" style="left: 60.4849px; top: 379.627px; font-size: 11.0761px; font-family: sans-serif; transform: scaleX(0.812608);">provides superior separation quality when compared to a state-</span><span style="left: 60.4849px; top: 391.934px; font-size: 11.0761px; font-family: sans-serif; transform: scaleX(0.822849);">of-the-art benchmark. Finally, an analysis on the effects of the</span><span style="left: 60.4849px; top: 404.242px; font-size: 11.0761px; font-family: sans-serif; transform: scaleX(0.878436);">introduced regularization term shows that the solution is in fact</span><span class="" style="left: 60.4849px; top: 416.548px; font-size: 11.0761px; font-family: sans-serif; transform: scaleX(0.811751);">steered toward a sparser representation.</span></p> Thadeu Luiz Barbosa Dias Wallace Alves Martins Luiz Wagner Pereira Biscainho ##submission.copyrightStatement## 2020-05-14 2020-05-14 35 1 103 112 10.14209/jcis.2020.11 A Photovoltaic System for Heterogeneous Networks: a Technical, Economic and Environmental Analysis <p>The modern society are daily becoming more internet connected. Such connection requires an unprecedented amount of energy to operate each piece of equipment that is part of the heterogeneous networks (HetNets). The network infrastructure is highly energy-consuming and producing a considerable amount of CO2. One strategy to minimize such energy consumption is making usage of renewable energy, such as solar and wind. This article aims to present a study of the technical, economic and environmental feasibility for the installation of photovoltaic harvesting systems in the context of HetNet and backhaul networks. This proposal is based on the use of analytical models to scale the deployment of the photovoltaic systems, considering costs associated with acquisition, operation, maintenance and adopted energy matrix of this system. The results indicate sustainable and financial viability with the adoption of photovoltaic systems when compared with the energy source mainly considered in the literature. Also, results highlight that adopted energy matrix and environmental parameters are key items, which must be highly considered when the overall mobile network infrastructure are planned.</p> Marcela Alves de Souza Fabricio de Souza Farias Hugo Pereira Kuribayashi Carlos R. L. Francês João C. W. A. Costa Diego Lisboa Cardoso ##submission.copyrightStatement## 2020-04-20 2020-04-20 35 1 90 102 10.14209/jcis.2020.10 Robust time delay estimation based on non-Gaussian impulsive acoustic channel <p>The aim of this letter is to propose a new robust method for source localization over impulsive noise and investigate its practical implications. The method uses a non-linear data transformation associated with the generalized cross-correlation technique. Hence, simulations and experiments show better performance than traditional methods without increasing the computational cost. Our practical experiments indicate the possibility of obtaining a correlated impulsive noise, in which the proposed method is still presenting accurate estimations.</p> Danilo Pena Arthur Lima Vicente Angelo de Sousa Junior Luiz Felipe Silveira Allan Medeiros ##submission.copyrightStatement## 2020-04-20 2020-04-20 35 1 86 89 10.14209/jcis.2020.9 Triple Band Reject Frequency Selective Surface with Application to 2.4 GHz Band <p>This paper presents the development of a frequency selective surface, FSS, with three bands of rejection, with the central bandwidth applied to the 2.4 GHz frequency band. The three rejection bands are obtained from the association of crossed- dipoles and matryoshka ring geometries. For each geometry the initial design equations are proposed. The procedure to obtain the matryoshka geometry is described step by step. Numerical results are presented for each geometry, and also to the associated&nbsp; &nbsp;geometries, considering different incident angles (θ=0°,15°,30° and 45°). The current distribution of each resonant frequency was shown, allowing to visualize the respective excited geometry. After the numerical results, we verify that the resonant frequencies associated to the respective geometry remains practically unchanged even for the associated geometries. A FSS prototype with the associated geometries was designed, fabricated, and characterized, with a very good agreement between numerical and experimental results, obtaining an attenuation of at least 15 dB in the 2.4 GHz frequency band.</p> Alfredo Gomes Neto Jefferson Costa e Silva Ianes Barbosa Grécia Coutinho Marina de Oliveira Alencar Diego Medeiros de Andrade ##submission.copyrightStatement## 2020-04-16 2020-04-16 35 1 77 85 10.14209/jcis.2020.8 Deep Reinforcement Learning for QoS-Constrained Resource Allocation in Multiservice Networks <p>In this article, we study a Radio Resource Allocation&nbsp;(RRA) that was formulated as a non-convex optimization&nbsp;problem whose main aim is to maximize the spectral efficiency&nbsp;subject to satisfaction guarantees in multiservice wireless systems.&nbsp;This problem has already been previously investigated in the&nbsp;literature and efficient heuristics have been proposed. However,&nbsp;in order to assess the performance of Machine Learning (ML)&nbsp;algorithms when solving optimization problems in the context&nbsp;of RRA, we revisit that problem and propose a solution based&nbsp;on a Reinforcement Learning (RL) framework. Specifically, a&nbsp;distributed optimization method based on multi-agent deep RL&nbsp;is developed, where each agent makes its decisions to find a&nbsp;policy by interacting with the local environment, until reaching&nbsp;convergence. Thus, this article focuses on an application of RL&nbsp;and our main proposal consists in a new deep RL based approach&nbsp;to jointly deal with RRA, satisfaction guarantees and Quality of&nbsp;Service (QoS) constraints in multiservice celular networks. Lastly,&nbsp;through computational simulations we compare the state-of-art&nbsp;solutions of the literature with our proposal and we show a near&nbsp;optimal performance of the latter in terms of throughput and&nbsp;outage rate.</p> Juno Vitorino Saraiva Iran Mesquita Braga Junior Victor Farias Monteiro Franciso Rafael Marques Lima Tarcisio Ferreira Maciel Walter da Cruz Freitas Junior Francisco Rodrigo Porto Cavalcanti ##submission.copyrightStatement## 2020-04-08 2020-04-08 35 1 66 76 10.14209/jcis.2020.7 The Usefulness of the Energy Harvested from Additive Noises in Power Line and Wireless Media <p>Aiming to come up with strategies for harvesting energy in hybrid power line communication (PLC)-wireless systems, this work focuses on the amount of energy that can be potentially harvested from the additive noise in electric power grids and in the air within residential facilities when the frequencies from 1.7 up to 100~MHz are taken into account. Based on statistical analyses of a residential data set, we show that the average power of the measured additive noise in the power line is higher in the morning than other periods of the day. Also, it is higher than the values from the energy harvested from in the air, in the same frequency band. Moreover, we show that the amount of energy harvested from these additive noises can yields achievable data rates between hundreds of kbps up to dozens of Mbps if hybrid PLC-wireless channels are used for data communication purposes.</p> Victor Fernandes Thiago Rodrigues Oliveira Moisés Vidal Ribeiro ##submission.copyrightStatement## 2020-03-29 2020-03-29 35 1 61 65 10.14209/jcis.2020.6 The Augmented Reality Telerehabilitation System for Powered Wheelchair User’s Training <p>Many people worldwide have been experimenting a decrease in their mobility as a result of aging, accidents and degenerative diseases. In many cases, a Powered Wheelchair (PW) is an alternative help. Currently in Brazil, patients can receive a PW from the Unified Health System, following prescription criteria. However, they do not have an appropriate previous training for driving the PW. Consequently, users might suffer accidents since a customized training protocol is not available. Nevertheless, due to financial and/or health limitations, many users are unable to attend a rehabilitation center. To overcome these limitations, we developed an Augmented Reality Telerehabilitation System Architecture based on the Power Mobility Road Test for supporting PW user’s training. In this system, the therapists can remotely customize and evaluate training tasks and the user can perform the training in safer conditions. The video stream and data transfer between each environment were made possible through UDP (User Datagram Protocol). To evaluate and present the system architecture potential, a preliminary test was conducted with 3 spinal cord injury participants. They performed 3 basic training protocols defined by a therapist. The following metrics were adopted for evaluation: number of control commands; elapsed time; number of collisions; biosignals. Also, a questionary was used to evaluate system features. Preliminary results demonstrated the specific needs of individuals using a PW thanks to adopted metrics (qualitative and emotional). Results have shown the need for a training system with customizable protocols to fulfill these needs. User's evaluation demonstrates that the combination of AR techniques with PMRT adaptations, increases user's well-being after training sessions. Furthermore, a training experience helps users to overcome their displacement problems, as well as for appointing challenges before large scale use. This system architecture allows further studies on telerehabilitation of PW users training.</p> Daniel Stefany Duarte Caetano Caroline Valentini Fernando Mattioli Paulo Camargos Thiago Sá Alexandre Cardoso Edgard Lamounier Eduardo Naves ##submission.copyrightStatement## 2020-03-03 2020-03-03 35 1 51 60 10.14209/jcis.2020.5