Vicente Angelo de Sousa Jr

Universidade Federal do Rio Grande do Norte | IIP · Departamento de Engenharia de Communicacoes

Due to the low cost of broadband systems, there is a substantial growth in the indoor deployment of networks based on IEEE 802.11 standards, and their expressive insertion in domestic and labor environments. The proximity of those systems to the general population has been raising questions about the risks of exposure to the so-called non-ionizing...

Recent studies and literature reviews have shown promising results for 3GPP system solutions in unlicensed bands when coexisting with Wi-Fi, either by using the duty cycle (DC) approach or licensed-assisted access (LAA). However, it is widely known that general performance in these coexistence scenarios is dependent on traffic and how the duty cycl...

Experimental tools are a key factor in both academic and industrial research communities to create design evaluations of new networking technologies that involve troubleshooting or changing the planning of deployed networks. Physical Software-Defined Radio (SDR) experimental platforms enable a design solution for the quick prototyping of wireless c...

It is crucial to monitor the levels of Non-Ionizing Radiation (NIR) to which the general population may be exposed and compare them to the limits defined in the current standards, in view of the rapid rise of communication services and the prospects of a connected society. A high number of people visits shopping malls and since these locations usua...

Electroencephalography (EEG) is a fundamental tool for understanding the brain’s electrical activity related to human motor activities. Brain-Computer Interface (BCI) uses such electrical activity to develop assistive technologies, especially those directed at people with physical disabilities. However, extracting signal features and patterns is st...

This work presents a Non-Ionizing Radiation (NIR) measurement campaign and proposes a specific measurement method for trajectography radars. This kind of radar has a high gain narrow beam antenna and emits a high power signal. Power density measurements from a C-band trajectography radar are carried out using bench equipment and a directional recei...

A tecnologia de acesso móvel passou por uma grande revolução e popularização nos últimos anos. Cada geração de tecnologia móvel forneceu melhorias significativas de desempenho, com mudanças rápidas em respostas às demandas de capacidade resultante do crescimento maciço do tráfego de dados em dispositivos móveis em todo mundo. A quinta geração (5G)...

Recently, the issue of sound quality inside vehicles has attracted interest from both researchers and industry alike due to health concerns and also to increase the appeal of vehicles to consumers. This work extends the analysis of interior acoustic noise inside a vehicle under several conditions by comparing measured power levels and two different...

LoRa is a physical layer technology with the ability to connect multiple devices in a wide area of coverage, with low power consumption and with interference robustness. In this Letter, we investigate the efficiency of LoRa to send multiple uplink streams, analyzing strategies of allocating the spreading factor for coverage or capacity enhancement.

This letter covers a broad comparison of methods for classification and regression applications for a user-level handover decision making in scenarios with adverse propagation conditions involving buildings, coverage holes, and shadowing effects. The simulation campaigns are based on network simulator ns-3. The comparison encompasses classical mach...

This work presents the Base-Band Sounding Tool (BSOT), a wideband channel sounding simulator with different scenarios and configurations, providing the channels characterization in terms of delay and Doppler spreading. BSOT follows COST 207 statistical channel model and the pulse compression technique with direct cross-correlation at the receiver....

The use of unmanned aerial vehicles (UAV) to provide services such as the Internet, goods delivery, and air taxis has become a reality in recent years. The use of these aircraft requires a secure communication between the control station and the UAV, which demands the characterization of the communication channel. This paper aims to present a measu...

Localization applications are widely used as an essential service in many systems, such as 5G device positioning, location of things (LoT), and speech source localization. Unlike classical GPS, the time difference of arrival (TDOA) approach estimates the angle of arrival using the signals received from a sensor array, allowing to determine the posi...

This work explores interference coordination techniques (inter-cell interference coordination, ICIC) based on fractional frequency reuse (FFR) as a solution for a multi-cellular scenario with user concentration varying over time. Initially, we present the problem of high user concentration along with their consequences. Next, the use of multiple-in...

This paper presents a statistical analysis of small-scale fading on static propagation environment due to the movement of people between antennas. We also analyze the influence of the antenna radiation pattern on narrowband-channel statistics. For this, we use signal samples received by omnidirectional and directional microstrip antenna. We evaluat...

Mobile communications are preparing for the incredible changes from \(4\mathrm{th} \,\hbox {Generation (4G)}\) to \(5\mathrm{th}\hbox { Generation (5G)}\) in the coming years. In this new generation, co-channel interference is one of the critical challenges to be tackled due to network densification by providing high data rates through several macr...

The use of clean communication paths underwater can enable important applications not only for the human being. Predictions of water-observation systems (e.g., oxygen levels, climate recording, pollutant contents) and monitoring/imaging animal activity (e.g., fish, micro-organisms) could anticipate actions to preserve underwater life in case of nat...

While the amount of telecommunications services grows rapidly in the whole world, humans get potentially more exposed to Non-Ionizing Radiation (NIR) from a number of different sources. Measurements of NIR levels are relevant in order to compare the results with national and international standards, aiming at the preservation of human health. Thus,...

Recentemente, a questão da qualidade sonora no interior de veículos tem atraído o interesse de pesquisadores e da indústria. Este trabalho, portanto, propõe um estudo bibliométrico sobre o tema. Embora o número de publicações esteja em crescimento, verifica-se uma discrepância entre o conhecimento produzido no meio acadêmico e suas aplicações em so...

Devido ao sucesso comercial da tecnologia Wi-Fi, há uma grande expectativa para versões evoluı́das de seus sistemas. Uma peça chave para concepção de novas funcionalidades e melhoria das existentes é prototipagem em software. Este artigo apresenta uma caracterização de desempenho do Wi-Fi usando o simulador ns-3, mostrando sua flexibilidade para mo...

Devido à popularização do Wi-Fi como alternativa para o acesso à internet, múltiplos tipos de serviços, com requisitos de tráfego diferentes, passaram a ser utilizados nesse tipo de rede. Este artigo apresenta um estudo sobre as categorias de acesso (AC) do padrão IEEE 802.11 que visam Qualidade de Serviço (QoS). O objetivo é utilizar a ferramenta...

This work focuses on acoustic analysis as a way of discriminating mineral oil, providing a robust technique, immune to electromagnetic noise, and in some cases, depending on the applied sensor, a low-cost technique. Thus, we propose a new method for the diagnosis of the quality of mineral oil used in electrical transformers, integrating a ferroelec...

Vehicular acoustic noise evaluations are a concern of researchers due to health and comfort effects on humans and are fundamental for anyone interested in mitigating audio noise. This paper focuses on the evaluation of the noise level inside a vehicle by using statistical tools. First, an experimental setup was developed with microphones and a micr...

The aim of this letter is to propose a new robust method for time delay estimation 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...

Cellular broadband Internet of Things (IoT) applications are expected to keep growing year-by-year, generating demands from high throughput services. Since some of these applications are deployed over licensed mobile networks, as long term evolution (LTE), one already common problem is faced: the scarcity of licensed spectrum to cope with the incre...

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, creat...

LoRa Wide Area Network (LoRaWAN) has become popular as an Internet of Things (IoT) enabler. The low cost, ease of installation and the capacity of fine-tuning the parameters make this network a suitable candidate for the deployment of smart cities. In northern Sweden, in the smart region of Skellefteå, we have deployed a LoRaWAN to enable IoT appli...

Specifically in telecommunications, the underwater environment is challenging and deprived of solutions from those related to the form of transmission, without cables or with cables, to those related to data routing (e.g., in a sensor network). This work proposes to make a collection of different prototyping tools for submarine network solutions in...

In recent years, a growing interest in research has been emerging in the area of submarine communications, given the potential of activities that this environment presents for humanity. The idea of structuring wireless underwater sensors networks has taken space in these studies, in order to enable such activities, embedding flexibility. In this co...

Recent literature demonstrated promising results of Long-Term Evolution (LTE) deployments over unlicensed bands when coexisting with Wi-Fi networks via the Duty-Cycle (DC) approach. However, it is known that performance in coexistence is strongly dependent on traffic patterns and on the duty-cycle ON–OFF rate of LTE. Most DC solutions rely on stati...

This paper aims to present a bibliometric study that contemplates papers using Software Defined Network to optimize the Mobile Ad Hoc Networks performance. Scopus and Web of Science databases were used. The results showed that the area is recent and it has presented a great increase in the publications number in last years. Several centers have dev...

Recent literature demonstrated promising results of Long-Term Evolution (LTE) deployments over unlicensed bands when coexisting with Wi-Fi networks via the Duty-Cycle (DC) approach. However, it is known that performance in coexistence is strongly dependent on traffic patterns and on the duty-cycle ON–OFF rate of LTE. Most DC solutions rely on stati...

In this letter, we propose a Machine learning (ML) solution for crowd-size classification in an indoor environment. Narrowband Radio frequency (RF) signals are used to identify a pattern according to the number of people. Experimental data collected by a low-cost software-defined radio platform is post-processed by applying a feature mapping along...

In general, acoustic channels are not Gaussian distributed neither are second-order stationary. Considering them for signal processing methods designed for Gaussian assumptions is inadequate, consequently yielding in poor performance of such methods. This paper presents an analysis for audio signal corrupted by impulsive noise using non-Gaussian mo...

There is substantial literature covering both problems and solutions related to the operation of Long Term Evolution (LTE) networks in unlicensed spectrum (LTE-U) while in coexistence with other technologies, such as Wi-Fi. However, a seldom explored scenario is the coexistence between multiple LTE-U networks. Within this scenario, a big issue is e...

We present a bibliometric study to survey trends related to NOMA (\textit{Non-Orthogonal Multiple Access}). This survey is important to researchers that are thinking to invest efforts in the NOMA technology and need to map their stage of development. We use the Web of Science and Scopus, with the purpose of identifying the related techniques and in...

LoRa has emerged as a prominent technology for the Internet of Things (IoT), with LoRa Wide Area Network (LoRaWAN) emerging as a suitable connection solution for smart things. The choice of the best location for the installation of gateways, as well as a robust network server configuration, are key to the deployment of a LoRaWAN. In this paper, we...

Heterogeneous Networks (HetNets) are considered a technology option capable of improving system capacity and spatial spectrum reuse. However, high spectrum reuse causes high inter-cell interference among macro and small cells. Almost Blank Subframe (ABS) is a method of the Enhanced Inter-Cell Interference Coordination (e-ICIC) framework proposed fo...

This paper presents a prospective analysis of the main trends related to the radar area. The research is justified by the necessity of a roadmap evaluation of the radar area in its general perspective. This study could be useful for guiding the industry/government investments or for giving directions for researches. The radar area is considerably w...

Resumo-Cerca de 70% da superfície da terrá e coberta poráguapor´porágua do mar, umá area ainda pouco explorada para fins de comunicaçcomunicaç˜comunicação. Desde aplicaçaplicaç˜aplicações comerciais a aplicaçaplicaç˜aplicações militares (envolvendo também a obtençobtenç˜obtenção e preservaçpreservaç˜preservação de recursos naturais), explorar comun...

About 70% of earth surface is covered with sea water, an area that is few explored in communication. Investigating submarine communications can be strategic and a competitive advantage to countries with long coast. This work aims at evaluating through software prototypes the performance of a communication over underwater acoustic channel (UAC) subj...

The introduction of a high number of small cells in cellular networks and the complementary adoption of WLAN technologies in unlicensed spectrum are interesting options to attend the increasing demand for Internet traffic in wireless broadband access networks. One alternative for integrating both solutions is the aggregation of ISM unlicensed spect...

Efficient Radio Resource Allocation (RRA) is of utmost importance for achieving maximum capacity in mobile networks. However, the performance assessment should take into account the main constraints of these networks. This letter presents important enhancements to RRA algorithms proposed in [1]. Prior work [1] ignores some important system constrai...

Unlicensed spectrum is increasingly being used by mobile operators to meet the mobile traffic demand, and Wi-Fi is foreseen as one of the technologies for implementing mobile traffic offloading. However, Wi-Fi efficiency does not scale well as node density increases, and IEEE 802.11ax Task Group (TGax) was created in 2014 for developing Wi-Fi techn...

The expansion of wireless broadband access network deployments is resulting in increased scarcity of available radio spectrum. It is very likely that in the near future, cellular technologies and wireless local area networks will need to coexist in the same unlicensed bands. However, the two most prominent technologies, LTE and Wi-Fi, were designed...

The default medium access mechanism for Wi-Fi, Distributed Coordination Function (DCF), is a simple contention based protocol aimed at providing a fair distribution of resources among Wi-Fi nodes. However, DCF suffers from significant performance degradation in the presence of dense deployments. Hence, improving the performance of the Wi-Fi MAC lay...

In this contribution, a hardware platform for cooperative sensing networks is presented with the use of Roys Largest Root Test, also known as a blindly combined energy detection scheme, such that the system is configured with three ETTUS USRPs N210 and one computer for processing. The hardware experiments were validated with simulations, and the re...

Modern wireless systems employ adaptive techniques to provide high throughput while observing desired coverage, QoS (quality of service) and capacity. An alternative to further enhance data rate is to apply cognitive radio concepts, where a system is able to exploit unused spectrum on existing licensed bands by “sensing” the spectrum and opportunis...

Modern wireless systems employ adaptive techniques to provide high throughput while observing desired coverage, Quality of Service (QoS) and capacity. An alternative to further enhance data rate is to apply cognitive radio concepts, where a system is able to exploit unused spectrum on existing licensed bands by sensing the spectrum and opportunisti...

To extend battery life, modern wireless systems implement Power Saving Mechanisms (PSMs). This work presents a performance evaluation of HTTP Web Browsing and Always-On traffic whithin joint IEEE 802.16e Sleep Mode and Idle Mode operation, on an accurate 802.16e PSM NS-2 simulation implementation. We first determine the most influencial PSM paramet...

This paper introduces new network architecture capable of providing a flexible and configurable Recommendation System in which network operator, subscribers and content providers could interact to each other by message exchanging. This solution considers multiple inputs provided by the user and context-based information of IP Multimedia Subsystem (...

In accordance with an example embodiment of the present invention, a method comprises collecting measurements from each of a plurality of mobile stations in a serving layer upon deciding that the serving layer is overloaded; computing a cost function for each of the mobile stations based on the collected measurements; selecting at least one mobile...

Energy availability is the main delimiter for usage time of mobile devices. As wireless network interfaces are usually the most power-demanding subsystem in a mobile device, mechanisms for their power consumption optimization are extensively researched. However, determining the power saving gains from using such optimizations is not an easy task, s...

Antenna diversity is a well-known technique to increase data rate and coverage in fading environments, and it can be applied both at the transmitter or at the receiver side of a transmission link. New broadband wireless systems, such as Mobile WiMAX (IEEE 802.16e-2005 standard), rely on several antenna diversity approaches like Maximum Ratio Combin...

In this work a tutorial about mobile WiMAX technology is presented, based on IEEE802.16e standards. A technical description of the radio interface of this technology will be made, and some aspects related to standardisation, regulation and business applications will be briefly analysed.

This paper presents the study of the access selection (AS) problem in a multi-access wireless network. The contributions of this paper could be classified in two groups. Firstly, we extend previous investigations in terms of performance results, regarding a system-level dynamic evaluation. Performance indicators like coverage, SNR, rate and offered...

Next generation wireless networks are expected to be composed of wireless systems based on different Radio Access Networks (RANs). This expectation is supported by the fact that no single RAN has been able to achieved all communication engineering requirements in the wireless domain and that an optimum trade-off among coverage, capacity, QoS and ef...

This paper proposes and evaluates power-based congestion control mechanisms in the WCDMA downlink air interface based on the functionalities of the call admission control (CAC), conversational service class rate adaptation (RA) via AMR codec and load control (LC) algorithms. It is verified by means of dynamic system level simulations that the conge...

In downlink WCDMA systems, QoS and load management can be performed by a call admission control (CAC) algorithm. The objective of CAC is to guarantee high capacity and system stability, by accepting or denying an arriving bearer service access to the system, depending on the system load, the interference it adds to and receives from the existing co...

The major purpose of this contribution is to analyze an hierarchical cell structure with a hot spot embedded in a WCDMA macrocellular system. Particular attention is paid to the impact of the introduction of smart antennas in this context. A system-level simulation approach is employed where we consider two main solutions to deal with the hot spot...