XL Simpósio Brasileiro de Telecomunicações e Processamento de Sinais

Many of the test statistics for spectrum sensing in cognitive radio networks make use of the received signal sample covariance matrix (SCM), which is the case of the Pietra-Ricci index detector (PRIDe). This article compares two hardware architectures for computing the SCM in field programmable gate array (FPGA). The coordinate rotation digital computer...

This work investigates the impact of different channels fadings on the favorable propagation, channel hardening, and spectral efficiency of the cell-free massive multiple-input multiple-output (MIMO) system. The analyzes consider both line-of-sight (LOS) and non-LOS (NLOS) channels in indoor and outdoor environments. Specifically, the channel may be...

Este trabalho apresenta um método de detecção de anomalias em vídeo baseado na decomposição dos seus quadros no subespaço de componentes de fundo gerado por um dicionário. O dicionário utilizado é baseado na decomposição de posto baixo proveniente da técnica de RobustPCA. Os resultados mostram que essa implementação fornece um resultado equivalente a...

We investigate distributed fiber optic sensing and machine-learning-based image analysis for road-speed estimation. Synthetic phase-sensitive optical time-domain reflectometer (ϕ-OTDR) traces are generated by the simulation of random road features such as car density and speed. Consecutive ϕ-OTDR traces are stacked generating images that are submitted to...

Orthogonal Frequency-Division Multiplexing (OFDM) is a technique used in several wireless communication systems. One impairment present in OFDM-based systems is the Carrier Frequency Offset (CFO). The objective of this article is to propose a semi-blind two-stage CFO estimation algorithm for OFDM and for an Orthogonal Frequency-Division Multiple Access...

Energy detection (ED) is a widely adopted technique for detecting primary signals in cognitive-radio-based spectrum sensing. However, sensitivity to uncertainties in the knowledge of noise power at receivers is the main drawback that limits the detection capacity of ED and gives rise to the phenomenon called signal-to-noise ratio wall (SNRw). This paper...

This research work presents a testbed for simulating an initial 5G NSA (Non Standalone) network to provide VoLTE (Voice over LTE) calls. The configuration testbed relies on using open-source projects as well as the Kamailio server for real-time communication and signaling messages using the SIP (Session Initiation Protocol) protocol of the IMS (IP...

The network architecture of a software defined networking (SDN) has as main characteristic to centralize the control of the network in a single asset, which makes this asset a target for denial of service (DoS) attacks. This article aims to demonstrate a way to mitigate denial of service attacks that focus on exploring the security of coupling multiple...

Considering 5G networks with multi-connectivity capability and deploying large antenna arrays operating in mmWaves, this paper performs two numerical analyses. In the first one, it is assumed that, increasing the number of antenna elements in the transmitter, the channel variations reduce, i.e., the channel "hardens". In the considered scenario, this...

This paper presents the application of two signal-processing techniques, Hanning window and zero padding, to the results of simulations of propagating waves using the FDTD method. Two problems involving rectangular resonant cavities are addressed: an empty cavity and a cavity partially filled with a dielectric. Frequency spectrum plots and tables with...