XLIII Simpósio Brasileiro de Telecomunicações e Processamento de Sinais

A caracterização do canal sem fio em função da linha de visada tem o potencial de aprimorar a alocação eficiente do fator de espalhamento em redes LoRaWAN. Ao adequar a alocação de fator de espalhamento e potência de transmissão às condições de cada canal, observa-se um aumento na taxa de entrega de pacotes. Baseado em simulações no software ns-3 com...

In this article, we analyze the effects of solar radiation on mmWave (25-60 GHz) radio links, both in isolation and when integrated into the 5G mobile network. We found that variations in solar flux deteriorate the signal-to-noise ratio and increase path loss - an impact that tends to worsen in Brazil due to the South Atlantic Magnetic Anomaly. Through...

O presente artigo apresenta uma antena de microfita quadrada, composta por duas camadas do laminado FR4 e dois patches truncados, projetada para operar com Polarização Circular à Direita (RHCP) nas bandas L1 (centrada em 1,575 GHz) e L5 (centrada em 1,176 GHz) do Sistema de Posicionamento Global (GPS). A antena foi excitada por meio de um único conector...

Accurate OSNR estimation is essential for maintaining signal quality in coherent optical communication systems. This work proposes a deep learning-based method for OSNR estimation using constellation diagrams as input. A dataset of over 19,000 images was generated through simulations with various modulation formats. We evaluated 15 CNN architectures,...

Este estudo apresenta uma abordagem para detecção inteligente de incêndios florestais utilizando visão computacional e Internet das Coisas (IoT), sendo seu foco no monitoramento da progressão e regressão dos focos de incêndio. A técnica proposta é baseada no algoritmo YOLOv11, que se destaca pela passagem da imagem na rede neural uma única vez,...

This paper analyzes the impact of analog front-end nonlinearities on the bit-error rate (BER) performance of massive multiple-input multiple-output (MIMO) systems, mainly focusing on the power amplifiers (PAs) nonlinearities of the solid-state am- plifier. Simulation results show that the PA nonlinearities degrade system BER, yielding SNR losses of...

We investigate practical challenges of estimating information-theoretic generalization bounds using neural mutual information estimators. Focusing on a Gaussian mean estimation task, we compare input--output (MI), individual-sample (ISMI), and conditional (CMI) formulations under varying sample sizes and regularization strategies. Through empirical...

In this study, the reduction of human electromagnetic exposure to millimeter waves is analyzed. Thus, the specific absorption rate (SAR) from mobile antennas used for next-generation 5G n78 and n258 communication frequencies is significantly decreased by an absorber based on periodically arranged metallic square spirals. The reduction of SAR with the...

This paper investigates the effectiveness of kernel-based adaptive filtering for digital predistortion in power amplifiers. Specifically, the EX-QKRLS algorithm, which incorporates concepts from the Kalman filter, is employed to model and compensate for the nonlinearities introduced during signal amplification, without requiring memory polynomials or...

This work presents a dual-antenna passive synthetic aperture direction-of-arrival (DoA) estimation approach for compact airborne sensors. A physics-based model is employed, incorporating spherical wave propagation, Doppler effects, and a 200 km line-of-sight, and is implemented in an in-house radar simulator. The corresponding Cramér-Rao lower bound...