Marcelo Segatto - Academia.edu (original) (raw)

Papers by Marcelo Segatto

Anais do XXV Simpósio Brasileiro de Telecomunicações

Considering a graph as a network of resistances, Klein and Randić [3] proposed the definition of ... more Considering a graph as a network of resistances, Klein and Randić [3] proposed the definition of a distance measure. Indeed, if each edge of the graph represents a resistance of 1Ω, the equivalent resistance of the graph between each pair of vertices may be used as a distance. Based upon random walks in graphs, Stephenson and Zelen [4] built a computational model to find the probability that each edge is used. From a mathematical point of view, both articles are based upon exactly the same model and the link between random walks and the electrical representation was established by Newman [5] when defining an alternative to Freeman’s betweenness centrality [9, 10] based upon random walks. In the present paper, the similitude between these two processes is exploited to propose a new random walks based distance measure that may be defined as the expected length of a walk between any pair of vertices. From this new definition, the RW Index is proposed that sums the expected walks length...

2019 SBMO/IEEE MTT-S International Microwave and Optoelectronics Conference (IMOC), 2019

A performance evaluation of the physical layer of the long-range (LoRa) technology is presented i... more A performance evaluation of the physical layer of the long-range (LoRa) technology is presented in this paper. An experimental setup with off-the-shelf LoRa wide area network (LoRaWAN) devices were prepared to demonstrate the feasibility of this technology. Feasible communication between a central oilproducing process used to monitor several oil wells, located in a rural area, was achieved at distances up to approx\approxapprox2.7 km, according to measurements of the average received signal indicators around -100dBm for an average SNR approx\approxapprox5.6dB. It is possible to conclude from the experimental results that LoRaWAN is a suitable long-range and low power wide area network for smart monitoring in oil Industries.

In this paper, we summarize some properties of the Cartesian product of graphs related to degree ... more In this paper, we summarize some properties of the Cartesian product of graphs related to degree and distance-based invariants. Then, we investigate how much a single edge or vertex removal in the Cartesian product of two connected graphs impacts: the distance between any pair of nodes, the average distance, and the diameter in the remaining graph.

This study analyzes the influence of the variability of topological characteristics of optical ne... more This study analyzes the influence of the variability of topological characteristics of optical networks in their desirable performance, with respect to the requirement of wavelengths. The studies were focused on real-world networks and random graphs with characteristics of realworld networks. It was observed that some topological features exalted in the literature may not necessarily be good representatives of the behavior of optical networks. 1 Introdução As redes ópticas de transporte (OTN Optical Transport Networks) se tornaram o ramo central da imensa malha de redes de comunicações da sociedade atual devido a vários fatores, como a sua grande capacidade de tráfego, velocidade e alcance. Vários canais independentes podem compartilhar a mesma fibra óptica, aumentado a taxa de dados sobre a mesma infraestrutura. Nas redes convencionais utiliza-se a tecnologia de Wavelength Division Multiplexing (WDM), permitindo assim a implementação de redes com roteamento de tráfego por comprimen...

In this paper, we establish the maximum number of basic shortest paths in Cartesian product graph... more In this paper, we establish the maximum number of basic shortest paths in Cartesian product graphs and bounds on the maximum number of the vertex-disjoint shortest paths and on this of the edgedisjoint shortest paths. To the best of our knowledge, the class of Cartesian product graphs has been intensively studied according to various invariants, except the maximum number of (basic, vertex-disjoint or edge-disjoint) shortest paths, whereas the latter invariants were investigated for other graph classes. The main contribution of this paper is to fill this gap. Moreover, we investigate the impact of a vertex or an edge removal on the maximum number of basic shortest paths in Cartesian product graphs.

2021 SBMO/IEEE MTT-S International Microwave and Optoelectronics Conference (IMOC)

2021 SBMO/IEEE MTT-S International Microwave and Optoelectronics Conference (IMOC)

In this paper we propose the use of twin graphs for optical transport network (OTN) physical topo... more In this paper we propose the use of twin graphs for optical transport network (OTN) physical topology design. Some properties inherent to twin graphs are fault tolerance, performance, cost, scalability, and planarity. Twin graphs can be easily generated by a recursive method. Moreover, the additional capacity required to implement path dedicated protection against single link or node failures is smaller in twin graphs than in existing OTN topologies.

Any telecommunication network is subject to a node or link failure at any given time. Such a fail... more Any telecommunication network is subject to a node or link failure at any given time. Such a failure may impact the quality of the services provided by the network, and therefore the network resilience. In this paper, we define two new measures for evaluating network resilience with respect to a node or link failure: the vertex residual mean distance and the edge residual mean distance, in short RMDs. The RMDs are graph invariants which measure the impact of the removal of an arbitrary vertex/edge on the mean distance of the original graph. Some authors investigated different graph invariants before and after a vertex or an edge removal. However, to our knowledge, none of them incorporated graph invariant with vertex/edge removal. We study the RMDs on diverse graph classes, such as cycle graphs, complete graphs, twin graphs and k-geodetically connected graphs. We establish tight lower bound of the RMDs and graphs reaching them, as well as non-tight upper bound of the RMDs. Moreover,...

In this work, we investigate the use of twin graphs as an alternative to model optical backbone n... more In this work, we investigate the use of twin graphs as an alternative to model optical backbone networks, as recently proposed in the literature [PCS13]. Twin graphs are suitable for resilient and cost-effective optical networks, because of the following property: any single node failure causes no impact on the pairwise hopcounts in the remaining network; and no other graphs with fewer links satisfy this property [FP97]. In recent works, a special family of 2-connected graphs called twin graphs has been proposed to model optical backbone topologies due to interesting properties with respect to fault tolerance, resilience, cost (in number of links) and scalability [PCS13]. Twin graphs belong to the class of 2-geodetically-connected graphs, which means that each of them provides at least two node-disjoint geodesics (i.e., shortest paths with respect to the number of links), for all non-adjacent node pairs. Moreover, no other graphs with fewer links satisfy this property [FP97]. Thus, ...

Anais de XXXVII Simpósio Brasileiro de Telecomunicações e Processamento de Sinais

Resumo-Metaheurísticas baseadas nos algoritmos Greedy Randomized Adaptive Search Procedure (GRASP... more Resumo-Metaheurísticas baseadas nos algoritmos Greedy Randomized Adaptive Search Procedure (GRASP) e Variable Neighborhood Descent (VND) foram propostas neste artigo para garantir confiabilidade no fronthaul óptico com functional split recomendado para a arquitetura de rede de telefonia móvel de quinta geração (5G). Uma comparação entre soluções geradas a partir do GRASP e outra a partir do GRASP/VND é realizada em cenários com variação da quantidade de recursos, do tamanho da rede e de opções do functional split, visando também atender a latência exigida na tecnologia 5G. Os resultados de simulação mostraram que a proposta GRASP/VND gerou soluções melhores em 60% dos 49 cenários avaliados.

Anais de XXXVII Simpósio Brasileiro de Telecomunicações e Processamento de Sinais

Resumo-Este trabalho estende a análise do conceito de frequências entrelaçadas para uma rede ópti... more Resumo-Este trabalho estende a análise do conceito de frequências entrelaçadas para uma rede óptica passiva (PON), utilizando multiplexação por divisão de comprimento de onda densa (DWDM). Um gerador óptico de pentes de frequências é usado para criar o padrão de entrelaçamento desejado. Para o sistema simulado utilizando modulação NRZ-OOK (Not Return to Zero-On-Off Keying), obteve-se taxa de transmissão de 50 Gbit/s (4 × 25 Gbit/s), enquanto que considerando-se DQPSK (Differential Quadrature Phase Shift Keying), chegou-se a 100 Gbit/s (4 × 25 Gbit/s). As simulações foram realizadas em Matlab para 20 km e 40 km de fibra monomodo em downstream.

2019 SBFoton International Optics and Photonics Conference (SBFoton IOPC)

Light plays an important role in life cycle: light is a normative issue and a common use requirem... more Light plays an important role in life cycle: light is a normative issue and a common use requirement which helps the perception and apprehension of formal and conceptual aspects. Specifically, in respect to the relationship between user and light, there are intrinsic physiological and psychological issues leading to an understanding between the threshold of human comfort and discomfort. The existing methods measure light at normal state of use and location, that is, they do not usually consider an exceptional condition. In special situations, a small amount of light can be judged inadequate under standards established by regulation; however, in a situation with lack of light, that minimum amount of illuminance, can offer a positive effect. This paper is a part of a methodological research and has as objective analyze a new assessment range, developed from the Useful Daylight Illuminance (UDI), based to justify the range below 100 lux of illuminance in the constructed environment natural lit, considering this still could be a valuable light.

IEEE Communications Letters

A closed-form expression for the bit-error-rate (BER) of constant envelope orthogonal frequency d... more A closed-form expression for the bit-error-rate (BER) of constant envelope orthogonal frequency division multiplexing (CE-OFDM) in intensity-modulated direct-detection optical systems is provided in this letter. To the best of our knowledge, this letter is the first that provides an expression of the BER that considers the impact of electrical phase modulation index, signal bandwidth, optical modulation index, and Mach–Zehnder modulator bias point. Simulation and experimental results are included to validate the accuracy of the expression, subject to an analysis of the impact of electrical phase modulation index and the level of subcarrier mapping. With the analytical expression, we are able to reduce the computation time in design and parameter optimization of optical systems based in the CE-OFDM.

Journal of Microwaves, Optoelectronics and Electromagnetic Applications

Optics Communications

Constant-envelope OFDM signals based on electrical phase modulation are proposed in visible light... more Constant-envelope OFDM signals based on electrical phase modulation are proposed in visible light communication (VLC) systems to adapt to the LEDs flicker requirements. Experimental results demonstrate that this peakto-average power ratio (PAPR) reduction technique thoroughly adapts to the flicker requirements in line-of-sight single-input single-output (SISO) VLC channels, at a cost of performance penalties, as indicated by the numerical evaluations provided in this paper. The performance of a 272.87 Mb/s CE-OFDM system, with 64-QAM subcarrier mapping in a bandwidth of 100 MHz, is compared with the performance of a conventional OFDM system, after propagation through SISO and multiple-input single-output (MISO) VLC channel models. Besides the strong dependence on the phase modulation index 2 ℎ, the simulation results show that, in the SISO scenario, the CE-OFDM technique introduces performance penalties. However, with 2 ℎ = 1.3, the phase modulation based scheme outperforms traditional OFDM systems in the MISO architecture, due to the transmission of low PAPR signals.

Applied Sciences

At the verge of the launch of the first commercial fifth generation (5G) system, trends in wirele... more At the verge of the launch of the first commercial fifth generation (5G) system, trends in wireless and optical networks are proceeding toward increasingly dense deployments, supporting resilient interconnection for applications that carry higher and higher capacity and tighter latency requirements. These developments put increasing pressure on network backhaul and drive the need for a re-examination of traditional backhaul topologies. Challenges of impending networks cannot be tackled by star and ring approaches due to their lack of intrinsic survivability and resilience properties, respectively. In support of this re-examination, we propose a backhaul topology design method that formulates the topology optimization as a graph optimization problem by capturing both the objective and constraints of optimization in graph invariants. Our graph theoretic approach leverages well studied mathematical techniques to provide a more systematic alternative to traditional approaches to backhau...

Journal of Microwaves, Optoelectronics and Electromagnetic Applications

This paper presents a theoretical and computational study on the analysis of parameters for distr... more This paper presents a theoretical and computational study on the analysis of parameters for distributed temperature sensing in optical fibers, based on spontaneous Raman scattering effect. The parameters studied were the optical power level, the range of frequency modulation and the length of the sensor element, as well as the application of optical frequency domain reflectometry (OFDR). Two different approaches of reading temperature information from the backscattered signal were also tested. First, one considered the pulse response, and later the ratio between the amplitudes of the detected signals were taken. Such analysis has shown the second method is more efficient to detect the peak of hot spot temperature in the fiber. Spatial resolution equal to 0.96 m and a temperature resolution of 0.089 ºC were achieved using singlemode fiber 30 meters long.

Anais do XXV Simpósio Brasileiro de Telecomunicações

Considering a graph as a network of resistances, Klein and Randić [3] proposed the definition of ... more Considering a graph as a network of resistances, Klein and Randić [3] proposed the definition of a distance measure. Indeed, if each edge of the graph represents a resistance of 1Ω, the equivalent resistance of the graph between each pair of vertices may be used as a distance. Based upon random walks in graphs, Stephenson and Zelen [4] built a computational model to find the probability that each edge is used. From a mathematical point of view, both articles are based upon exactly the same model and the link between random walks and the electrical representation was established by Newman [5] when defining an alternative to Freeman’s betweenness centrality [9, 10] based upon random walks. In the present paper, the similitude between these two processes is exploited to propose a new random walks based distance measure that may be defined as the expected length of a walk between any pair of vertices. From this new definition, the RW Index is proposed that sums the expected walks length...

2019 SBMO/IEEE MTT-S International Microwave and Optoelectronics Conference (IMOC), 2019

A performance evaluation of the physical layer of the long-range (LoRa) technology is presented i... more A performance evaluation of the physical layer of the long-range (LoRa) technology is presented in this paper. An experimental setup with off-the-shelf LoRa wide area network (LoRaWAN) devices were prepared to demonstrate the feasibility of this technology. Feasible communication between a central oilproducing process used to monitor several oil wells, located in a rural area, was achieved at distances up to approx\approxapprox2.7 km, according to measurements of the average received signal indicators around -100dBm for an average SNR approx\approxapprox5.6dB. It is possible to conclude from the experimental results that LoRaWAN is a suitable long-range and low power wide area network for smart monitoring in oil Industries.

In this paper, we summarize some properties of the Cartesian product of graphs related to degree ... more In this paper, we summarize some properties of the Cartesian product of graphs related to degree and distance-based invariants. Then, we investigate how much a single edge or vertex removal in the Cartesian product of two connected graphs impacts: the distance between any pair of nodes, the average distance, and the diameter in the remaining graph.

This study analyzes the influence of the variability of topological characteristics of optical ne... more This study analyzes the influence of the variability of topological characteristics of optical networks in their desirable performance, with respect to the requirement of wavelengths. The studies were focused on real-world networks and random graphs with characteristics of realworld networks. It was observed that some topological features exalted in the literature may not necessarily be good representatives of the behavior of optical networks. 1 Introdução As redes ópticas de transporte (OTN Optical Transport Networks) se tornaram o ramo central da imensa malha de redes de comunicações da sociedade atual devido a vários fatores, como a sua grande capacidade de tráfego, velocidade e alcance. Vários canais independentes podem compartilhar a mesma fibra óptica, aumentado a taxa de dados sobre a mesma infraestrutura. Nas redes convencionais utiliza-se a tecnologia de Wavelength Division Multiplexing (WDM), permitindo assim a implementação de redes com roteamento de tráfego por comprimen...

In this paper, we establish the maximum number of basic shortest paths in Cartesian product graph... more In this paper, we establish the maximum number of basic shortest paths in Cartesian product graphs and bounds on the maximum number of the vertex-disjoint shortest paths and on this of the edgedisjoint shortest paths. To the best of our knowledge, the class of Cartesian product graphs has been intensively studied according to various invariants, except the maximum number of (basic, vertex-disjoint or edge-disjoint) shortest paths, whereas the latter invariants were investigated for other graph classes. The main contribution of this paper is to fill this gap. Moreover, we investigate the impact of a vertex or an edge removal on the maximum number of basic shortest paths in Cartesian product graphs.

2021 SBMO/IEEE MTT-S International Microwave and Optoelectronics Conference (IMOC)

2021 SBMO/IEEE MTT-S International Microwave and Optoelectronics Conference (IMOC)

In this paper we propose the use of twin graphs for optical transport network (OTN) physical topo... more In this paper we propose the use of twin graphs for optical transport network (OTN) physical topology design. Some properties inherent to twin graphs are fault tolerance, performance, cost, scalability, and planarity. Twin graphs can be easily generated by a recursive method. Moreover, the additional capacity required to implement path dedicated protection against single link or node failures is smaller in twin graphs than in existing OTN topologies.

Any telecommunication network is subject to a node or link failure at any given time. Such a fail... more Any telecommunication network is subject to a node or link failure at any given time. Such a failure may impact the quality of the services provided by the network, and therefore the network resilience. In this paper, we define two new measures for evaluating network resilience with respect to a node or link failure: the vertex residual mean distance and the edge residual mean distance, in short RMDs. The RMDs are graph invariants which measure the impact of the removal of an arbitrary vertex/edge on the mean distance of the original graph. Some authors investigated different graph invariants before and after a vertex or an edge removal. However, to our knowledge, none of them incorporated graph invariant with vertex/edge removal. We study the RMDs on diverse graph classes, such as cycle graphs, complete graphs, twin graphs and k-geodetically connected graphs. We establish tight lower bound of the RMDs and graphs reaching them, as well as non-tight upper bound of the RMDs. Moreover,...

In this work, we investigate the use of twin graphs as an alternative to model optical backbone n... more In this work, we investigate the use of twin graphs as an alternative to model optical backbone networks, as recently proposed in the literature [PCS13]. Twin graphs are suitable for resilient and cost-effective optical networks, because of the following property: any single node failure causes no impact on the pairwise hopcounts in the remaining network; and no other graphs with fewer links satisfy this property [FP97]. In recent works, a special family of 2-connected graphs called twin graphs has been proposed to model optical backbone topologies due to interesting properties with respect to fault tolerance, resilience, cost (in number of links) and scalability [PCS13]. Twin graphs belong to the class of 2-geodetically-connected graphs, which means that each of them provides at least two node-disjoint geodesics (i.e., shortest paths with respect to the number of links), for all non-adjacent node pairs. Moreover, no other graphs with fewer links satisfy this property [FP97]. Thus, ...

Anais de XXXVII Simpósio Brasileiro de Telecomunicações e Processamento de Sinais

Resumo-Metaheurísticas baseadas nos algoritmos Greedy Randomized Adaptive Search Procedure (GRASP... more Resumo-Metaheurísticas baseadas nos algoritmos Greedy Randomized Adaptive Search Procedure (GRASP) e Variable Neighborhood Descent (VND) foram propostas neste artigo para garantir confiabilidade no fronthaul óptico com functional split recomendado para a arquitetura de rede de telefonia móvel de quinta geração (5G). Uma comparação entre soluções geradas a partir do GRASP e outra a partir do GRASP/VND é realizada em cenários com variação da quantidade de recursos, do tamanho da rede e de opções do functional split, visando também atender a latência exigida na tecnologia 5G. Os resultados de simulação mostraram que a proposta GRASP/VND gerou soluções melhores em 60% dos 49 cenários avaliados.

Anais de XXXVII Simpósio Brasileiro de Telecomunicações e Processamento de Sinais

Resumo-Este trabalho estende a análise do conceito de frequências entrelaçadas para uma rede ópti... more Resumo-Este trabalho estende a análise do conceito de frequências entrelaçadas para uma rede óptica passiva (PON), utilizando multiplexação por divisão de comprimento de onda densa (DWDM). Um gerador óptico de pentes de frequências é usado para criar o padrão de entrelaçamento desejado. Para o sistema simulado utilizando modulação NRZ-OOK (Not Return to Zero-On-Off Keying), obteve-se taxa de transmissão de 50 Gbit/s (4 × 25 Gbit/s), enquanto que considerando-se DQPSK (Differential Quadrature Phase Shift Keying), chegou-se a 100 Gbit/s (4 × 25 Gbit/s). As simulações foram realizadas em Matlab para 20 km e 40 km de fibra monomodo em downstream.

2019 SBFoton International Optics and Photonics Conference (SBFoton IOPC)

Light plays an important role in life cycle: light is a normative issue and a common use requirem... more Light plays an important role in life cycle: light is a normative issue and a common use requirement which helps the perception and apprehension of formal and conceptual aspects. Specifically, in respect to the relationship between user and light, there are intrinsic physiological and psychological issues leading to an understanding between the threshold of human comfort and discomfort. The existing methods measure light at normal state of use and location, that is, they do not usually consider an exceptional condition. In special situations, a small amount of light can be judged inadequate under standards established by regulation; however, in a situation with lack of light, that minimum amount of illuminance, can offer a positive effect. This paper is a part of a methodological research and has as objective analyze a new assessment range, developed from the Useful Daylight Illuminance (UDI), based to justify the range below 100 lux of illuminance in the constructed environment natural lit, considering this still could be a valuable light.

IEEE Communications Letters

A closed-form expression for the bit-error-rate (BER) of constant envelope orthogonal frequency d... more A closed-form expression for the bit-error-rate (BER) of constant envelope orthogonal frequency division multiplexing (CE-OFDM) in intensity-modulated direct-detection optical systems is provided in this letter. To the best of our knowledge, this letter is the first that provides an expression of the BER that considers the impact of electrical phase modulation index, signal bandwidth, optical modulation index, and Mach–Zehnder modulator bias point. Simulation and experimental results are included to validate the accuracy of the expression, subject to an analysis of the impact of electrical phase modulation index and the level of subcarrier mapping. With the analytical expression, we are able to reduce the computation time in design and parameter optimization of optical systems based in the CE-OFDM.

Journal of Microwaves, Optoelectronics and Electromagnetic Applications

Optics Communications

Constant-envelope OFDM signals based on electrical phase modulation are proposed in visible light... more Constant-envelope OFDM signals based on electrical phase modulation are proposed in visible light communication (VLC) systems to adapt to the LEDs flicker requirements. Experimental results demonstrate that this peakto-average power ratio (PAPR) reduction technique thoroughly adapts to the flicker requirements in line-of-sight single-input single-output (SISO) VLC channels, at a cost of performance penalties, as indicated by the numerical evaluations provided in this paper. The performance of a 272.87 Mb/s CE-OFDM system, with 64-QAM subcarrier mapping in a bandwidth of 100 MHz, is compared with the performance of a conventional OFDM system, after propagation through SISO and multiple-input single-output (MISO) VLC channel models. Besides the strong dependence on the phase modulation index 2 ℎ, the simulation results show that, in the SISO scenario, the CE-OFDM technique introduces performance penalties. However, with 2 ℎ = 1.3, the phase modulation based scheme outperforms traditional OFDM systems in the MISO architecture, due to the transmission of low PAPR signals.

Applied Sciences

At the verge of the launch of the first commercial fifth generation (5G) system, trends in wirele... more At the verge of the launch of the first commercial fifth generation (5G) system, trends in wireless and optical networks are proceeding toward increasingly dense deployments, supporting resilient interconnection for applications that carry higher and higher capacity and tighter latency requirements. These developments put increasing pressure on network backhaul and drive the need for a re-examination of traditional backhaul topologies. Challenges of impending networks cannot be tackled by star and ring approaches due to their lack of intrinsic survivability and resilience properties, respectively. In support of this re-examination, we propose a backhaul topology design method that formulates the topology optimization as a graph optimization problem by capturing both the objective and constraints of optimization in graph invariants. Our graph theoretic approach leverages well studied mathematical techniques to provide a more systematic alternative to traditional approaches to backhau...

Journal of Microwaves, Optoelectronics and Electromagnetic Applications

This paper presents a theoretical and computational study on the analysis of parameters for distr... more This paper presents a theoretical and computational study on the analysis of parameters for distributed temperature sensing in optical fibers, based on spontaneous Raman scattering effect. The parameters studied were the optical power level, the range of frequency modulation and the length of the sensor element, as well as the application of optical frequency domain reflectometry (OFDR). Two different approaches of reading temperature information from the backscattered signal were also tested. First, one considered the pulse response, and later the ratio between the amplitudes of the detected signals were taken. Such analysis has shown the second method is more efficient to detect the peak of hot spot temperature in the fiber. Spatial resolution equal to 0.96 m and a temperature resolution of 0.089 ºC were achieved using singlemode fiber 30 meters long.