Journal of Communication and Information Systems https://jcis.sbrt.org.br/jcis <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 June 2020, Prof. Rausley Adriano Amaral de Souza from National Institute of Telecommunications (Inatel) and Prof. José Cândido Silveira Santos Filho from University of Campinas (UNICAMP) 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="https://creativecommons.org/licenses/by/3.0/" 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="http://opcit.eprints.org/oacitation-biblio.html" target="_new">The Effect of Open Access</a>).</li></ol></ol><p>___________</p> LoRa System for Monitoring and Facial Recognition https://jcis.sbrt.org.br/jcis/article/view/745 <p>With the increasing tendency of incorporating technology into environments and activities in everyday life, new methods are being proposed to better integrate devices and mankind. Networks designed for monitoring areas through video and image systems are being implemented in several applications.<br>Recent studies have shown interest from both the academy and industry to integrate wireless surveillance networks with low-cost and long range transmission technologies, such as LoRa (Long Range). With the intention to explore this topic, this work presents the development of a system prototype for intelligent<br>monitoring as a basis to future implementation of low-cost LoRa-based Wireless Image Sensor Networks (WISN). The system developed consists of a processing unit, a data routing interface and multiple sensor nodes. Its operation is autonomous and initiated through the detection of human presence, by the sensor<br>node, capturing an image of the individuals present at each detection. The data is transmitted through LoRa devices to the central hub, where python-based methods of facial detection and recognition are employed. Several tests were performed to both adjust the system and to verify its efficiency. The results achieved<br>were satisfactory, indicating the viability of the proposed low-cost LoRa-based WISN.</p> Vitor J. C. Rodrigues Douglas F. Medeiros Fabrício B. S. Carvalho Waslon Terllizzie A. Lopes ##submission.copyrightStatement## https://creativecommons.org/licenses/by/4.0 2021-01-08 2021-01-08 36 1 1 16 10.14209/jcis.2021.1 Propagation models for 5G signals in the 60 GHz band https://jcis.sbrt.org.br/jcis/article/view/738 <p>Wireless data traffic is increasing due to the growing numbers of mobile phones and devices connected to the network. A large number of devices needs to be interconnected so it becomes necessary to increase the spectrum band and data traffic simultaneously to have the network working properly, those are some of goals of the 5G network. Frequencies in the range of 20 GHz until 300 GHz are in a spectrum band called millimeter waves band, also known by mmWave. This paper discusses the usage of 60 GHz band in the 5G networks. The 60 GHz band has the advantages like frequency reuse and short-distance connectivity.&nbsp; This paper also argues the problems that may arise from the choosing 60 GHz band. Wireless data traffic is increasing due to the growing numbers of mobile phones and devices connected to the network. A large number of devices needs to be interconnected so it becomes necessary to increase the spectrum band and data traffic simultaneously to have the network working properly, those are some of goals of the 5G network. Frequencies in the range of 20 GHz until 300 GHz are in a spectrum band called millimeter waves band, also known by mmWave. This paper discusses the usage of 60 GHz band in the 5G networks. The 60 GHz band has the advantages like frequency reuse and short-distance connectivity.&nbsp; This paper also argues the problems that may arise from the choosing 60 GHz band.</p> Gustavo Kreuzer Marengo Gabriel Eduardo Silva Leite Arismar Cerqueira Sodré Junior Luciano Leonel Mendes ##submission.copyrightStatement## https://creativecommons.org/licenses/by/4.0 2020-12-31 2020-12-31 36 1 357 369 10.14209/jcis.2020.36 Spectrum Efficient GFDM Based on Faster Than Nyquist Signaling https://jcis.sbrt.org.br/jcis/article/view/747 <p>Future mobile communication system will provide high data rates for a miscellany of new applications. Spectrum efficiency is a key performance indicator that must be considerably improved for the beyond 5G networks. In this paper,&nbsp;a new approach to increase the waveform spectrum efficiency is investigated. This novel schemes combines the faster-thanNyquist signaling with generalized frequency division multiplexing, resulting in a scheme that can hold the main benefits of this innovative waveform with the high spectral efficiency gain. The scheme proposed in this paper abandons the orthogonality principle for the time-frequency grid, reducing the spacing between the subcarriers. The reduced subcarrier spacing does not affect the minimum distance among the transmitted sequences, if the Mazo’s limit is respected and the data can be recovered by a non-linear receiver without bit error penalties. In this paper, maximum likelihood receiver will be used for a proof of conception, showing that the bit error performance is equivalent to the one achieved by orthogonal systems. The system will be integrated with a forward error control scheme, showing that the proposed scheme can be fully integrated with modern error control codes, while improving the spectrum efficiency by 20%.</p> Mariana Baracat de Mello Luciano Leonel Mendes Tiago Cardoso Barbosa ##submission.copyrightStatement## https://creativecommons.org/licenses/by/4.0 2020-12-28 2020-12-28 36 1 349 356 10.14209/jcis.2020.35 A Noise-Reduction Method With Coherence Enhancement for Binaural Hearing Aids https://jcis.sbrt.org.br/jcis/article/view/758 <p>In this work, a variation of the multichannel Wiener filter (MWF) for noise reduction in binaural hearing aid applications is proposed. This method provides improved spatial preservation for acoustic scenarios comprised of one single-point target (speech) and one single-point interfering (noise) acoustic sources. It employs a regularization penalty term based on the inverse of the magnitude of the interaural coherence (IC), with the aim of enhancing the original azimuth perception of the interferent source. The proposed penalty term artificially intensifies the IC of the residual interference, increasing similarity in both ears. This is of special value for low-coherent reverberant acoustic signals, in which the reliability of the received binaural cues associated to the single-point interferent source was degraded by multiple acoustic reflections. Simulation results obtained with objective criteria show that, in addition of providing improved spatial preservation for the interferent source, the proposed approach may also provide higher noise reduction performance as compared to the conventional MWF approach. Further, it also yields an extended range for the target and interference spatial-preservation trade-off, as compared to a previously developed competing method. Psychoacoustic experiments with normal hearing volunteers corroborate theoretical and simulation findings.</p> Johnny Werner Marcio Holsbach Costa ##submission.copyrightStatement## https://creativecommons.org/licenses/by/4.0 2020-12-21 2020-12-21 36 1 338 348 10.14209/jcis.2020.34 Meta-heuristic procedure for enhanced spectrum fragmentation assessment in elastic optical networks https://jcis.sbrt.org.br/jcis/article/view/746 <p>This work proposes the use of a procedure for improving the loss of capacity assessment of heterogeneous bandwidth requests in the min slot-continuity capacity loss (MSCL) spectrum allocation algorithm. The particle swarm optimization (PSO) method is used to determine the best relationship between the number of requested slots and the amount of contiguous free slots in the requested and interfering paths. We also incorporate in the MSCL the influence of the number of hops of a route in its capacity evaluation. Considerable reductions in the path request blocking probability are achieved when the technique is applied, particularly when the number of hops is included to the evaluation.</p> Clayton Natal Lira Raul Almeida Júnior Daniel Chaves Helio Waldman Karcius Assis ##submission.copyrightStatement## https://creativecommons.org/licenses/by/4.0 2020-12-18 2020-12-18 36 1 333 337 10.14209/jcis.2020.33 Interference Mitigation for Dynamic TDD Networks Employing Sounding Signals https://jcis.sbrt.org.br/jcis/article/view/736 <p>The requirements of fifth-generation (5G) mobile communications include services with low delay and high throughput. Network densification is pointed to as a promising method to increase the network capacity. However, this solution brings new problems, such as the fast variation in traffic demands among access nodes (ANs) and between uplink and downlink, leading to high delays. To solve the traffic issues in dense networks, dynamic time division duplex (DTDD) is pointed as a possible solution. This strategy creates a new kind of interference between ANs and user equipments (UEs) called cross-interference. Therefore, obtaining channel state information (CSI) of cross-interference channels is essential for implementing interference mitigation methods, such as interference alignment, coordinated beamforming, resource schedulers, among others. Hence, this work proposes methods to estimate the intended and interfering channels based on sounding reference signal (SRS) and/or demodulation reference signal (DMRS). A coordinated scheme is developed to assign sounding signals in the network and reduce the interference perceived during the channel sounding, which improves the channel estimation quality. Furthermore, a refined successive interference cancellation (SIC) algorithm is proposed for estimating the channel. To assess system performance, a zero-forcing beamforming algorithm has been developed based on the CSI acquired with the proposed methods. This algorithm handles the degrees of freedom issues when ANs are operating in opposite directions. The numerical results show that the improved channel quality provided by the proposed estimation algorithm increases network capacity.</p> Darlan Cavalcante Moreira Lászlon R. Costa Yuri C. B. Silva Igor M. Guerreiro ##submission.copyrightStatement## https://creativecommons.org/licenses/by/4.0 2020-12-08 2020-12-08 36 1 320 332 10.14209/jcis.2020.32 The Heuristic for Hardware Dimensioning Considering Tidal Effect https://jcis.sbrt.org.br/jcis/article/view/735 <p>The increase in the volume of services and applications, in addition to the accelerated growth in wireless access demands, represent significant challenges for the fifth generation (5G) of mobile networks. The daily large-scale migration of people in urban centers is another aspect of impact, as it incurs in the Tidal Effect. It generates natural traffic fluctuation throughout the day and makes it difficult for network dimensioning, control and management, resulting in low efficiency in the use of network resources. Based on data extracted from mobile subscribers' movement in the current network architecture, where a database with New York city geolocation information was used, a heuristic with two provisioning approaches (one based on aggregate throughput and one on the number of connected users) is proposed. This heuristic aims to meet the imminent demands given the physical limitation of hardware resources in future mobile networks. Results point that the network provisioning strategy met the scenario's traffic variability, reducing the number of active antennas by 13\% and the Blocked User Probability by 3.7\%, maximizing the Baseband Unit (BBU) efficiency and quantifying the Small Cells (SCs) needed to meet network demands.</p> Igor Wenner Silva Falcão Rafael Fogarolli Vieira Paulo Henrique Alves Pereira Marcos Cesar da Rocha Seruffo Diego Lisboa Cardoso ##submission.copyrightStatement## https://creativecommons.org/licenses/by/4.0 2020-12-03 2020-12-03 36 1 311 319 10.14209/jcis.2020.31 Bias-Compensated Estimator for Intrinsic Dimension and Differential Entropy https://jcis.sbrt.org.br/jcis/article/view/728 <p><strong>Intrinsic dimension and differential entropy estimators are studied in this paper, including their systematic bias.&nbsp;</strong><strong>A pragmatic approach for joint estimation and bias correction&nbsp;</strong><strong>of these two fundamental measures is proposed. Shared steps&nbsp;</strong><strong>on both estimators are highlighted, along with their useful</strong><br><strong>consequences to data analysis. It is shown that both estimators&nbsp;</strong><strong>can be complementary parts of a single approach, and that the&nbsp;</strong><strong>simultaneous estimation of differential entropy and intrinsic dimension give meaning to each other, where estimates at different&nbsp;</strong><strong>observation scales convey different perspectives of underlying</strong><br><strong>manifolds. Experiments with synthetic and real datasets are&nbsp;</strong><strong>presented to illustrate how to extract meaning from visual&nbsp;</strong><strong>inspections, and how to compensate for biases.</strong></p> Jugurta Montalvão, Ph.D. Jânio Canuto, Ph.D. Luiz Miranda, Ms.C. ##submission.copyrightStatement## https://creativecommons.org/licenses/by/4.0 2020-12-03 2020-12-03 36 1 300 310 10.14209/jcis.2020.30 Decoupling and Matching Strategies for Compact Antenna Arrays https://jcis.sbrt.org.br/jcis/article/view/699 <p>This paper proposes and evaluates three strategies of joint decoupling and impedance matching networks (DMN) for antenna arrays. Since MIMO technology presents antenna arrays which can be formatted with elements of the order of tens to hundreds, several effects due to this structure have emerged, such as mutual coupling and impedance matching among antenna elements in array. Therefore, the treatment of these issues seeks to solve problems such as the degradation of the performance of the communications system. The first method called DMN with Lumped Elements (DMN-LE) performs the decoupling and impedance matching steps with capacitors and inductors. The second method is called DMN with Ring Hybrid (DMN-RH). It utilizes a microstrip line in the ring form. With this approach is due achieves first the decoupling followed by impedance matching step. The third method is called Networkless Decoupling and Matching (NDM). It brings a concept of decoupling without the presence of a network itself. This enables modeling an antenna array that performs DMN operations in a simplified and compact manner. A comparison of the methods is performed both<br>analytically and via computer simulations. We conclude that the third method is promising new alternative approach.</p> Francisco Estevão Simão Pereira Josef A. Nossek F. Rodrigo P. Cavalcanti ##submission.copyrightStatement## https://creativecommons.org/licenses/by/4.0 2020-12-01 2020-12-01 36 1 290 299 10.14209/jcis.2020.29 A Machine Learning Approach for Handover in LTE Networks with Signal Obstructions https://jcis.sbrt.org.br/jcis/article/view/715 <p>Legacy cell-deployment strategies have been adapted to fulfill the increasing demand for wireless broadband internet access. One of them, the Hierarchical Cell Structure (HCS), that is already in use in LTE-A and it is considered essential for the 5G, consists of the deployment of several types of small cells under the umbrella of macrocells, creating overlaid coverages. Due to their low power and bellow-rooftop-level, sometimes indoor base stations, the small cells are severely affected by the surrounding obstacles, making the perceived Quality of Service (QoS) of the users subject to fast variations, thus rendering ineffective the classical approaches to mobility management, that are unable to predict those severe fading situations (coverage holes). Considering the amount of available information on the network performance and the evolution of real-time processing capabilities, the enhancement of LTE functionalities (such as the handover) by means of machine learning algorithms became possible. This work proposes and evaluates the performance of a machine learning based approach to handover in scenarios with the presence of signal-blocking obstacles. We use the ns-3 simulation for our proof of concept simulations. Our machines learn from experience and they are, therefore, able to choose the eNB that will most likely offer the user the highest long term QoS after the handover procedure, even in severe propagation conditions. The proposed schemes substantially improve the users' QoS in certain circumstances.</p> Tarciana Cabral de Brito Guerra Ycaro Ravel Dantas Vicente Angelo Sousa Jr ##submission.copyrightStatement## https://creativecommons.org/licenses/by/4.0 2020-11-18 2020-11-18 36 1 271 289 10.14209/jcis.2020.28