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Publications

Publications by CTM

2019

Efficient CIEDE2000-based Color Similarity Decision for Computer Vision

Authors
Pereira, A; Carvalho, P; Coelho, G; Corte-Real, L;

Publication
IEEE Transactions on Circuits and Systems for Video Technology

Abstract

2019

Stereo vision system for human motion analysis in a rehabilitation context

Authors
Matos, AC; Terroso, TA; Corte Real, L; Carvalho, P;

Publication
Computer Methods in Biomechanics and Biomedical Engineering: Imaging and Visualization

Abstract
The present demographic trends point to an increase in aged population and chronic diseases which symptoms can be alleviated through rehabilitation. The applicability of passive 3D reconstruction for motion tracking in a rehabilitation context was explored using a stereo camera. The camera was used to acquire depth and color information from which the 3D position of predefined joints was recovered based on: kinematic relationships, anthropometrically feasible lengths and temporal consistency. Finally, a set of quantitative measures were extracted to evaluate the performed rehabilitation exercises. Validation study using data provided by a marker based as ground-truth revealed that our proposal achieved errors within the range of state-of-the-art active markerless systems and visual evaluations done by physical therapists. The obtained results are promising and demonstrate that the developed methodology allows the analysis of human motion for a rehabilitation purpose. © 2018, © 2018 Informa UK Limited, trading as Taylor & Francis Group.

2019

A Comprehensive Study On Enterprise Wi-Fi Access Points Power Consumption

Authors
Silva, P; Almeida, NT; Campos, R;

Publication
IEEE Access

Abstract

2019

Energy Consumption Management for Dense Wi-Fi Networks

Authors
Silva, P; Almeida, NT; Campos, R;

Publication
IFIP Wireless Days

Abstract
Wi-Fi networks lack energy consumption management mechanisms. In particular, during nighttime periods, the energy waste may be significant, since all Access Points (APs) are kept switched on even though there is minimum or null traffic demand. The fact that more than 80% of all wireless traffic is originated or terminated indoor, and served by Wi-Fi, has led the scientific community to look into energy saving mechanisms for Wi-Fi networks. State of the art solutions address the problem by switching APs on and off based on manually inserted schedules or by analyzing real-time traffic demand. The first are vendor specific; the second may induce frequent station (STA) handoffs, which has an impact on network performance. The lack of implementability of solutions is also a shortcoming in most works.We propose an algorithm, named Energy Consumption Management Algorithm (ECMA), that learns the daytime and nighttime periods of the Wi-Fi network. ECMA was designed having in mind its implementability over legacy Wi-Fi equipment. At daytime, the radio interfaces of the AP (2.4 GHz and 5 GHz) are switched on and off automatically, according to the traffic demand. At nighttime, clusters of APs, covering the same area, are formed, leaving one AP always switched on for basic coverage and the redundant APs swichted off to maximize energy savings, while avoiding coverage and performance hampering. Simulation results show energy savings of up to 50% are possible using the ECMA algorithm. © 2019 IEEE.

2019

Green Mobile Networks for 5G and Beyond

Authors
Masoudi, M; Khafagy, MG; Conte, A; El Amine, A; Francoise, B; Nadjahi, C; Salem, FE; Labidi, W; Sural, A; Gati, A; Bodere, D; Arikan, E; Aklamanu, F; Louahlia Gualous, H; Lallet, J; Pareek, K; Nuaymi, L; Meunier, L; Silva, P; Almeida, NT; Chahed, T; Sjolund, T; Cavdar, C;

Publication
IEEE ACCESS

Abstract
The heated 5G network deployment race has already begun with the rapid progress in standardization efforts, backed by the current market availability of 5G-enabled network equipment, ongoing 5G spectrum auctions, early launching of non-standalone 5G network services in a few countries, among others. In this paper, we study current and future wireless networks from the viewpoint of energy efficiency (EE) and sustainability to meet the planned network and service evolution toward, along, and beyond 5G, as also inspired by the findings of the EU Celtic-Plus SooGREEN Project. We highlight the opportunities seized by the project efforts to enable and enrich this green nature of the network as compared to existing technologies. In specific, we present innovative means proposed in SooGREEN to monitor and evaluate EE in 5G networks and beyond. Further solutions are presented to reduce energy consumption and carbon footprint in the different network segments. The latter spans proposed virtualized/cloud architectures, efficient polar coding for fronthauling, mobile network powering via renewable energy and smart grid integration, passive cooling, smart sleeping modes in indoor systems, among others. Finally, we shed light on the open opportunities yet to be investigated and leveraged in future developments.

2019

Resonant tunneling diode photodetectors for optical communications

Authors
Watson, S; Zhang, WK; Tavares, J; Figueiredo, J; Cantu, H; Wang, J; Wasige, E; Salgado, H; Pessoa, L; Kelly, A;

Publication
Microwave and Optical Technology Letters

Abstract
Optical modulation characteristics of resonant tunneling diode photodetectors (RTD-PD) are investigated. Intensity modulated light excites the RTD-PDs to conduct data experiments. Simple and complex data patterns are used with results showing data rates up to 80 and 200 Mbit/s, respectively. This is the first demonstration of complex modulation using resonant tunneling diodes. © 2019 The Authors. Microwave and Optical Technology Letters published by Wiley Periodicals, Inc.

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