Fernando J. Velez (M’93–SM’05) received the Licenciado, M.Sc. and Ph.D. degrees in Electrical and Computer Engineering from Instituto Superior Técnico, Technical University of Lisbon in 1993, 1996 and 2001, respectively. Since 1995 he has been with the Department of Electromechanical Engineering of Universidade da Beira Interior, Covilhã, Portugal, where he is Assistant Professor, and he is also a researcher at Instituto de Telecomunicações. Fernando was an IEF Marie Curie Research Fellow in King’s College London in 2008/09 (OPTIMOBILE IEF) and a Marie Curie ERG fellow at Universidade da Beira Interior from 2010 until March 2013 (PLANOPTI ERG). He made or makes part of the teams of several European and Portuguese research projects on mobile communications and he was or is the coordinator of six Portuguese projects. He is the author of 160 publications, including two books. Prof. Velez is the coordinator of the WG2 (on Cognitive Radio/Software Defined Radio Co-existence Studies) of COST IC0905 “TERRA”. His main research areas are cellular planning tools, traffic from mobility, cross-layer design, radio resource management, spectrum sharing/coexistence/aggregation, and cost/revenue performance of advanced mobile communication systems.
Proc. of ANT 2024 - The 15th Intl. Conf. on Ambient Systems, Networks and Technologies, 2024
The need for creative solutions in real-time health monitoring has been highlighted by the rise i... more The need for creative solutions in real-time health monitoring has been highlighted by the rise in health-related incidents involving drivers of motor vehicles. It has led to the development of wearable technology that seamlessly integrates with the Internet of Medical Things (IoMT) to improve driver safety and healthcare responsiveness. The development of a revolutionary wearable technology system is presented in this study as an innovative approach to vehicle safety and healthcare. This system's real-time ability to track a driver's health is a significant development in guaranteeing driver safety and wellness. The study examines the hardware component's complex design and implementation, particularly concerning the printed circuit board (PCB) layout and electrical schematic. The gadget emphasizes wearability, robustness, affordability, and user-friendliness and is a shining example of valuable and effective medical technology. The research delves deeper into possible improvements for the system, like adding complex algorithms and a user-friendly interface. Enhancing user involvement and system intelligence hopes to maximize the system's potential for real-time health monitoring. The significance of this study in utilizing Internet of Medical Things (IoMT) technology is highlighted by its junction with multiple fields, including electronics, hardware engineering, human-computer interaction, and health informatics. This dissertation emphasizes the potential of wearable technology in bridging the gap between healthcare monitoring and vehicle safety by focusing on real-time health monitoring in the automotive context.
This paper compares the service quality between 4G and 5G New Radio (NR) among different sub-6 GH... more This paper compares the service quality between 4G and 5G New Radio (NR) among different sub-6 GHz frequency bands in an urban micro-cellular outdoor setting. An updated version of LTE-Sim is considered to obtain the exponential effective signal-to-interference-plus-noise ratio in 4G while determining the modulation and coding scheme. System capacity is obtained by considering a video application at 3.1 Mb/s and the proportional fair (PF) scheduler while comparing 4G and 5G NR through system-level simulations (the 5G-air-simulator is considered for 5G NR). The modified largest weighted delay first (MLWDF) scheduler is compared with the PF, though only in 4G. Optimal system performance is reached both in 4G and 5G NR for cell radii longer than two times the breakpoint distance (or beyond), which are preferable compared to the shortest values for the cell radius. We have learned that the packet loss ratio (PLR) is higher for the cell radii, R, shorter than breakpoint distance, d′ BP. For d′BP ≤ R ≤ 1000 m, the PLR first decreases and then increases. For a target PLR < 2%, in 4G, the highest maximum average goodput is obtained with the M-LWDF scheduler (10-25% increase). This maximum occurs at the 2.6 GHz and 3.5 GHz frequency bands for 300 ≤ R ≤ 500 m, while at 5.62 GHz the highest goodput occurs for the longest Rs. With 5G NR and the PF, the maximum average goodput increases, in our simulations, from ≈ 14.1 (in 4G) to 26.1 Mb/s (20 MHz bandwidth).
Extended reality (XR) is bridging the gap between virtual and real-world interactions enabling us... more Extended reality (XR) is bridging the gap between virtual and real-world interactions enabling users to interact in realistic virtual worlds, removing physical obstacles, and establishing shared areas that promote greater comprehension and teamwork. The growing demand for high-frequency 5G communication systems supporting these new applications motivates the need of compact and efficient antennas capable of operating at millimeter-wave frequency bands. This work explores how the use of photonic crystal (PhC) leverages the properties of a multi-band antenna operating within the 27.0 GHz and 41.49 GHz resonant bands. The High-Frequency Structure Simulator (HFSS) software is utilized in this paper to outline a comprehensive design and modeling approach for the proposed microstrip patch antenna.The design process involves optimizing the geometry and periodicity of the PhC structure to obtain resonant modes at the desired frequency bands by exploiting its bandgap properties, whilst enabling high quality resonances within the targeted frequency bands. The electromagnetic simulations and numerical analysis results demonstrate that the designed multi-band PhC-based antenna achieves a gain of 9.57 dBi. The resonant modes exhibit high quality factors, resulting in improved radiation efficiency. The proposed PhC-based antenna compact size, high gain, and multiple resonant bands make it suitable for a wide range of applications, including nextgeneration wireless communication systems supporting XR, radar systems, or satellite communications in the upper frequency bands.
IEEE International Mediterranean Conference on Communications and Networking – MeditCom 2024, 2024
Given the proliferation of connected devices and the prioritization of real-time data acquisition... more Given the proliferation of connected devices and the prioritization of real-time data acquisition across various scenarios, enhancing the energy efficiency within Wireless Sensor Networks (WSNs) is of paramount importance. This work has focused on the IEEE 802.15.4 standard and addresses existing medium access control protocols such as CSMA or Slotted ALOHA and proposes refinements in the Slotted ALOHA protocol through incorporating techniques like Binary Exponential Backoff (BEB) and Q-learning. These enhancements have demonstrated to be promising in terms of average delay reduction, energy efficiency and bolstered network throughput. As it facilitates more efficient energy management it constitutes a robust alternative to conventional CSMA in WSN MAC sub-layer protocols.
This research aims to contribute to enhancing road safety through the development and exploration... more This research aims to contribute to enhancing road safety through the development and exploration of an intelligent wristbandbased health monitoring solution for car drivers. It focuses on using various sensors, such as the photoplethysmogram (PPG) and an accelerometer, to accurately estimate the drivers' heart rate. The primary goal was to create a robust and accurate model capable of real-time heart rate estimation from PPG signals, with the potential to improve the effectiveness of Internet of Medical Things (IoMT) applications in the healthcare sector. The study delves into the multiple processing steps involved in improving the quality of data to make it suitable for efficient processing by the deep learning model, encompassing data analysis, signal interpretation, and applying diverse techniques such as filters, data shifting, and data manipulation. The research integrated the leave-onesession-out (LOSO) cross-validation technique for model training and evaluation alongside fine-tuning hyperparameters to optimize model performance and efficiency. The achieved Mean Absolute Error (MAE) of 3.450 ± 1.324 bpm and Mean Squared Error (MSE) of 69.50 ± 93.57 bpm 2 represent notable outcomes, resulting in a 54.9% improvement in MAE from the original study. Additionally, the research integrated the model into a user-friendly mobile application, visually presenting the results and enabling users to examine their health status in real-time. These findings highlight the significance of meticulous data analysis and processing in wearable device applications and the high accuracy of the proposed model.
In this chapter we propose a scenario for interoperability between high-speed downlink packet acc... more In this chapter we propose a scenario for interoperability between high-speed downlink packet access (HSDPA) and Wi-Fi. This scenario involves the end-user traveling in a public transportation system and requesting multimedia services to the operator. The interoperability between HSDPA and Wi-Fi (IEEE 802.11e standard) radio access technologies (RATs) is first addressed, a topology in which the user has access to both RATs was considered, together with a common radio resource management (CRRM) to manage the connections. We reached the conclusion that the CRRM enables to increase the system throughput when the load thresholds are set to 0.6 for HSDPA and 0.53 for Wi-Fi. Then, spectrum aggregation is implemented in HSDPA. A resource allocation (RA) algorithm allocates user packets to the available radio resources (in this case Node Bs operating at 2 and 5 GHz are available) in order to satisfy user requirements. Simulation results show that gains up to 22% may be achieved. We have also sought the most efficient way to manage routing packets inside the Wi-Fi network. The proposal which uses links with higher throughputs enables to reach the best results, with gains up to 300% in the packet delivery ratio. Finally, we discuss the challenges that need to be addressed in order to materialise the envisaged cognitive radio scenario in public transportation.
Page 1. Chapter 3 Medium Access Control Layer Ramjee Prasad and Fernando J. Velez Abstract The IE... more Page 1. Chapter 3 Medium Access Control Layer Ramjee Prasad and Fernando J. Velez Abstract The IEEE 802.16 Medium Access Control (MAC) protocol supports point-to-multipoint (PtM) and mesh broadband very high peak ...
IEEE International Symposium on Personal, Indoor and Mobile Radio Communications, PIMRC, 2006
It is shown that enhanced UMTS is an affordable solution for providing the required network quali... more It is shown that enhanced UMTS is an affordable solution for providing the required network quality and to reduce infrastructure investments in offices scenarios. System capacity results are obtained by using a system level simulator which considers traffic characterisation parameters and services usage in detail, among other. Results for the most profitable cell radius are obtained via an optimisation procedure
ABSTRACT In this paper Enhanced UMTS offices scenarios and classes of services up to wideband are... more ABSTRACT In this paper Enhanced UMTS offices scenarios and classes of services up to wideband are taken into account. A model is proposed for optimising Enhanced UMTS based in costs and revenues. A system level simulator is used to obtain the blocking probability, and other QoS measures, e.g., handover failure probability and delay. Using these results, one obtains the system capacity, i.e., the supported fraction of active users and throughput for a given grade of service. The profit (in percentage) was obtained, and the optimum (most profitable) cell radius was found. A higher number of pico-cells (with a cell radius around 34 m) will be a profitable solution for the optimisation of network planning. This will also allow for increasing system capacity and reducing prices.
IEEE International Symposium on Personal, Indoor and Mobile Radio Communications, PIMRC, 2010
Frederico Varela, Pedro Sebastião, Américo Correia, Member, IEEE, Francisco Cercas, Member, IEEE ... more Frederico Varela, Pedro Sebastião, Américo Correia, Member, IEEE, Francisco Cercas, Member, IEEE ISCTE-LUI/Instituto de Telecomunicações Av.ª das Forças Armadas 1649-026 Lisboa, Portugal fredericovarela@gmail.com, pedro.sebastiao@lx.it.pt, ...
2020 12th International Symposium on Communication Systems, Networks and Digital Signal Processing (CSNDSP), 2020
This paper presents a summary of the main research directions being followed in TeamUp5G European... more This paper presents a summary of the main research directions being followed in TeamUp5G European Training Network. This project is teaming up a new generation of researchers and entrepreneurs ready to address complex engineering problems and innovation to work both at university and industry in the 5G field. Research is focused on radio access network (RAN) techniques for 5G, considering ultra-dense mobile networks as a key ingredient of the mobile networks and their evolution. It covers a wide spread of topics from physical layer and medium access control to applications, looking at spectrum sharing and energy efficiency as important features.
AbstractA multi-service traffic model is proposed, and its validation is achieved by using event... more AbstractA multi-service traffic model is proposed, and its validation is achieved by using event-based simulation results. In the single-service case, theoretical and experimental results for ON-OFF blocking probability are close to each other, and there is an almost perfect ...
Proc. of ANT 2024 - The 15th Intl. Conf. on Ambient Systems, Networks and Technologies, 2024
The need for creative solutions in real-time health monitoring has been highlighted by the rise i... more The need for creative solutions in real-time health monitoring has been highlighted by the rise in health-related incidents involving drivers of motor vehicles. It has led to the development of wearable technology that seamlessly integrates with the Internet of Medical Things (IoMT) to improve driver safety and healthcare responsiveness. The development of a revolutionary wearable technology system is presented in this study as an innovative approach to vehicle safety and healthcare. This system's real-time ability to track a driver's health is a significant development in guaranteeing driver safety and wellness. The study examines the hardware component's complex design and implementation, particularly concerning the printed circuit board (PCB) layout and electrical schematic. The gadget emphasizes wearability, robustness, affordability, and user-friendliness and is a shining example of valuable and effective medical technology. The research delves deeper into possible improvements for the system, like adding complex algorithms and a user-friendly interface. Enhancing user involvement and system intelligence hopes to maximize the system's potential for real-time health monitoring. The significance of this study in utilizing Internet of Medical Things (IoMT) technology is highlighted by its junction with multiple fields, including electronics, hardware engineering, human-computer interaction, and health informatics. This dissertation emphasizes the potential of wearable technology in bridging the gap between healthcare monitoring and vehicle safety by focusing on real-time health monitoring in the automotive context.
This paper compares the service quality between 4G and 5G New Radio (NR) among different sub-6 GH... more This paper compares the service quality between 4G and 5G New Radio (NR) among different sub-6 GHz frequency bands in an urban micro-cellular outdoor setting. An updated version of LTE-Sim is considered to obtain the exponential effective signal-to-interference-plus-noise ratio in 4G while determining the modulation and coding scheme. System capacity is obtained by considering a video application at 3.1 Mb/s and the proportional fair (PF) scheduler while comparing 4G and 5G NR through system-level simulations (the 5G-air-simulator is considered for 5G NR). The modified largest weighted delay first (MLWDF) scheduler is compared with the PF, though only in 4G. Optimal system performance is reached both in 4G and 5G NR for cell radii longer than two times the breakpoint distance (or beyond), which are preferable compared to the shortest values for the cell radius. We have learned that the packet loss ratio (PLR) is higher for the cell radii, R, shorter than breakpoint distance, d′ BP. For d′BP ≤ R ≤ 1000 m, the PLR first decreases and then increases. For a target PLR < 2%, in 4G, the highest maximum average goodput is obtained with the M-LWDF scheduler (10-25% increase). This maximum occurs at the 2.6 GHz and 3.5 GHz frequency bands for 300 ≤ R ≤ 500 m, while at 5.62 GHz the highest goodput occurs for the longest Rs. With 5G NR and the PF, the maximum average goodput increases, in our simulations, from ≈ 14.1 (in 4G) to 26.1 Mb/s (20 MHz bandwidth).
Extended reality (XR) is bridging the gap between virtual and real-world interactions enabling us... more Extended reality (XR) is bridging the gap between virtual and real-world interactions enabling users to interact in realistic virtual worlds, removing physical obstacles, and establishing shared areas that promote greater comprehension and teamwork. The growing demand for high-frequency 5G communication systems supporting these new applications motivates the need of compact and efficient antennas capable of operating at millimeter-wave frequency bands. This work explores how the use of photonic crystal (PhC) leverages the properties of a multi-band antenna operating within the 27.0 GHz and 41.49 GHz resonant bands. The High-Frequency Structure Simulator (HFSS) software is utilized in this paper to outline a comprehensive design and modeling approach for the proposed microstrip patch antenna.The design process involves optimizing the geometry and periodicity of the PhC structure to obtain resonant modes at the desired frequency bands by exploiting its bandgap properties, whilst enabling high quality resonances within the targeted frequency bands. The electromagnetic simulations and numerical analysis results demonstrate that the designed multi-band PhC-based antenna achieves a gain of 9.57 dBi. The resonant modes exhibit high quality factors, resulting in improved radiation efficiency. The proposed PhC-based antenna compact size, high gain, and multiple resonant bands make it suitable for a wide range of applications, including nextgeneration wireless communication systems supporting XR, radar systems, or satellite communications in the upper frequency bands.
IEEE International Mediterranean Conference on Communications and Networking – MeditCom 2024, 2024
Given the proliferation of connected devices and the prioritization of real-time data acquisition... more Given the proliferation of connected devices and the prioritization of real-time data acquisition across various scenarios, enhancing the energy efficiency within Wireless Sensor Networks (WSNs) is of paramount importance. This work has focused on the IEEE 802.15.4 standard and addresses existing medium access control protocols such as CSMA or Slotted ALOHA and proposes refinements in the Slotted ALOHA protocol through incorporating techniques like Binary Exponential Backoff (BEB) and Q-learning. These enhancements have demonstrated to be promising in terms of average delay reduction, energy efficiency and bolstered network throughput. As it facilitates more efficient energy management it constitutes a robust alternative to conventional CSMA in WSN MAC sub-layer protocols.
This research aims to contribute to enhancing road safety through the development and exploration... more This research aims to contribute to enhancing road safety through the development and exploration of an intelligent wristbandbased health monitoring solution for car drivers. It focuses on using various sensors, such as the photoplethysmogram (PPG) and an accelerometer, to accurately estimate the drivers' heart rate. The primary goal was to create a robust and accurate model capable of real-time heart rate estimation from PPG signals, with the potential to improve the effectiveness of Internet of Medical Things (IoMT) applications in the healthcare sector. The study delves into the multiple processing steps involved in improving the quality of data to make it suitable for efficient processing by the deep learning model, encompassing data analysis, signal interpretation, and applying diverse techniques such as filters, data shifting, and data manipulation. The research integrated the leave-onesession-out (LOSO) cross-validation technique for model training and evaluation alongside fine-tuning hyperparameters to optimize model performance and efficiency. The achieved Mean Absolute Error (MAE) of 3.450 ± 1.324 bpm and Mean Squared Error (MSE) of 69.50 ± 93.57 bpm 2 represent notable outcomes, resulting in a 54.9% improvement in MAE from the original study. Additionally, the research integrated the model into a user-friendly mobile application, visually presenting the results and enabling users to examine their health status in real-time. These findings highlight the significance of meticulous data analysis and processing in wearable device applications and the high accuracy of the proposed model.
In this chapter we propose a scenario for interoperability between high-speed downlink packet acc... more In this chapter we propose a scenario for interoperability between high-speed downlink packet access (HSDPA) and Wi-Fi. This scenario involves the end-user traveling in a public transportation system and requesting multimedia services to the operator. The interoperability between HSDPA and Wi-Fi (IEEE 802.11e standard) radio access technologies (RATs) is first addressed, a topology in which the user has access to both RATs was considered, together with a common radio resource management (CRRM) to manage the connections. We reached the conclusion that the CRRM enables to increase the system throughput when the load thresholds are set to 0.6 for HSDPA and 0.53 for Wi-Fi. Then, spectrum aggregation is implemented in HSDPA. A resource allocation (RA) algorithm allocates user packets to the available radio resources (in this case Node Bs operating at 2 and 5 GHz are available) in order to satisfy user requirements. Simulation results show that gains up to 22% may be achieved. We have also sought the most efficient way to manage routing packets inside the Wi-Fi network. The proposal which uses links with higher throughputs enables to reach the best results, with gains up to 300% in the packet delivery ratio. Finally, we discuss the challenges that need to be addressed in order to materialise the envisaged cognitive radio scenario in public transportation.
Page 1. Chapter 3 Medium Access Control Layer Ramjee Prasad and Fernando J. Velez Abstract The IE... more Page 1. Chapter 3 Medium Access Control Layer Ramjee Prasad and Fernando J. Velez Abstract The IEEE 802.16 Medium Access Control (MAC) protocol supports point-to-multipoint (PtM) and mesh broadband very high peak ...
IEEE International Symposium on Personal, Indoor and Mobile Radio Communications, PIMRC, 2006
It is shown that enhanced UMTS is an affordable solution for providing the required network quali... more It is shown that enhanced UMTS is an affordable solution for providing the required network quality and to reduce infrastructure investments in offices scenarios. System capacity results are obtained by using a system level simulator which considers traffic characterisation parameters and services usage in detail, among other. Results for the most profitable cell radius are obtained via an optimisation procedure
ABSTRACT In this paper Enhanced UMTS offices scenarios and classes of services up to wideband are... more ABSTRACT In this paper Enhanced UMTS offices scenarios and classes of services up to wideband are taken into account. A model is proposed for optimising Enhanced UMTS based in costs and revenues. A system level simulator is used to obtain the blocking probability, and other QoS measures, e.g., handover failure probability and delay. Using these results, one obtains the system capacity, i.e., the supported fraction of active users and throughput for a given grade of service. The profit (in percentage) was obtained, and the optimum (most profitable) cell radius was found. A higher number of pico-cells (with a cell radius around 34 m) will be a profitable solution for the optimisation of network planning. This will also allow for increasing system capacity and reducing prices.
IEEE International Symposium on Personal, Indoor and Mobile Radio Communications, PIMRC, 2010
Frederico Varela, Pedro Sebastião, Américo Correia, Member, IEEE, Francisco Cercas, Member, IEEE ... more Frederico Varela, Pedro Sebastião, Américo Correia, Member, IEEE, Francisco Cercas, Member, IEEE ISCTE-LUI/Instituto de Telecomunicações Av.ª das Forças Armadas 1649-026 Lisboa, Portugal fredericovarela@gmail.com, pedro.sebastiao@lx.it.pt, ...
2020 12th International Symposium on Communication Systems, Networks and Digital Signal Processing (CSNDSP), 2020
This paper presents a summary of the main research directions being followed in TeamUp5G European... more This paper presents a summary of the main research directions being followed in TeamUp5G European Training Network. This project is teaming up a new generation of researchers and entrepreneurs ready to address complex engineering problems and innovation to work both at university and industry in the 5G field. Research is focused on radio access network (RAN) techniques for 5G, considering ultra-dense mobile networks as a key ingredient of the mobile networks and their evolution. It covers a wide spread of topics from physical layer and medium access control to applications, looking at spectrum sharing and energy efficiency as important features.
AbstractA multi-service traffic model is proposed, and its validation is achieved by using event... more AbstractA multi-service traffic model is proposed, and its validation is achieved by using event-based simulation results. In the single-service case, theoretical and experimental results for ON-OFF blocking probability are close to each other, and there is an almost perfect ...
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Papers by Fernando José da Silva Velez