Luís Almeida

University of Porto | UP · Departamento de Engenharia Eletrotécnica e de Computadores

Unmanned Aerial Vehicle (UAV) swarms play an effective role in timely data collection from ground sensors in remote and hostile areas. Optimizing the collective behavior of swarms can improve data collection performance. This paper puts forth a new mean field flight resource allocation optimization to minimize age of information (AoI) of sensory da...

Operating autonomous vehicles (AVs) and human-driven vehicles (HVs) at urban intersections while observing requirements of safety and service level is complex due not only to the existence of multiple inflow and outflow lanes, conflicting crossing zones, and low-speed conditions but also due to differences between control mechanisms of HVs and AVs....

An intersection area is a common space that must be efficiently shared over time between vehicles with conflicting trajectories from several road lanes. Numerous traffic light control (TLC) strategies have been presented to address this. The main objective is periodically switching intersection access between road lanes by permitting vehicles seque...

The increasing prominence of concepts such as Smart Production and Industrial Internet of Things (IIoT) within the context of Industry 4.0 has introduced a new set of requirements for the engineering of industrial systems, including support for dynamic environments, timeliness guarantees, support for heterogeneity, interoperability and reliability....

This research aims to assess the signal propagation behavior of millimeter waves (mmWaves) over maritime environ- ments. It focuses on the path loss performance of shore-to-vessel and vessel-to-vessel overwater communication at 28 GHz when considering line-of-sight conditions. The study is conducted by means of synthetic simulations at four differe...

The delays imposed by an intersection management (IM) system are a measure of the Quality of Service (QoS) provided to vehicles at signalized intersections (SIs). The QoS of the IM system can be related to the variability of travel time, speed, and capacity. Incorporating these factors, we defined the response time (RT) for any vehicle served by th...

An intersection area is a common space that must be efficiently shared over time between vehicles with conflicting trajectories from several road lanes. Numerous traffic light control (TLC) strategies have been presented to address this. The main objective is periodically switching intersection access between road lanes by permitting vehicles seque...

This article presents a novel centrality-driven gateway designation framework for the improved real-time performance of low-power wireless sensor networks (WSNs) at system design time. We target time-synchronized channel hopping (TSCH) WSNs with centralized network management and multiple gateways with the objective of enhancing traffic schedulabil...

In urban road transportation, intersections are traffic bottlenecks with increased waiting delays and associated adverse effects. A recently proposed intelligent intersection management (IIM) approach, the Synchronous Intersection Management Protocol (SIMP), synchronizes the vehicles access to simple single-lane isolated intersections, outperformin...

Despite the explosion of IoT deployments at Internet Service Provider (ISP) customer networks, such devices remain vulnerable to cyber-attacks. We present a ML-based anomaly detection system, to be deployed at the Customer Premises Equipment (CPE), that leverages several One-Class Classification algorithms and majority voting to detect anomalous ne...

Vehicle waiting time or stopped delay is one of the major disadvantages of employing signalized intersections (SIs) in road networks. The waiting time delays occur when vehicles stop in the queue, waiting to access the SI, and vary from road lane to road lane with the intersection management (IM) protocol used. In this research line, we propose an...

Private vehicles are expected to continue representing a large share of the urban traffic requiring intelligent management to provide safe and efficient urban mobility. In this context, it is imperative to mitigate traffic congestion and associated travel delays to improve the quality of life of urban dwellers. This paper explores the global perfor...

Unmanned vehicles used in ocean science, defense operations and commercial activities collect large amounts of data that is further processed onshore. For real-time information exchange, the wireless link between the unmanned vehicle and onshore devices must be reliable. In this work, we empirically evaluate a WiFi link between an autonomous underw...

Distributed Embedded Systems (DESs) carrying out critical tasks must be highly reliable and hard in real-time. Moreover, to operate in dynamic operational contexts in an effective and efficient manner, they must also be adaptive. Adaptivity is particularly interesting from a dependability perspective, as it can be used to develop dynamic fault tole...

Low-power wide-area networks are extending beyond the conventional terrestrial domain. Coastal zones, rivers, wetlands, among others, are nowadays common deployment settings for Internet-of-Things nodes where communication technologies such as LoRa are becoming popular. In this article, we investigate large-scale fading dynamics of LoRa line-of-sig...

This letter proposes a multi-gateway designation framework to design real-time wireless sensor networks (WSNs) improving traffic schedulability, i.e., meeting the traffic time constraints. To this end, we resort to Spectral Clustering un-supervised learning that allows defining arbitrary k disjoint clusters without knowledge of the nodes physical p...

This research proposes a novel minimal-overlap centrality-driven gateway designation method for real-time wireless sensor networks (WSNs). The goal is to enhance network schedulability by design, particularly, by exploiting the relationship between path node-overlaps and gateway designation. To this aim, we define a new metric termed minimal-overla...

This research proposes a co-design framework for scheduling, routing and gateway designation to improve the real-time performance of low-power wireless mesh networks. We target time-synchronized channel hopping (TSCH) networks with centralized network management and a single gateway. The end goal is to exploit existing trade-offs between the three...

MQTT is one of the most popular application-layer protocols used in the scope of the Internet-of-Things (IoT) and Industrial-Internet-of-Things (IIoT), given its suitability for resource-constrained embedded systems. However, MQTT Quality-of-Service policies do not support timeliness requirements, which is common in IIoT. The literature reports sev...

Unmanned aerial vehicles (UAVs), in particular multirotors, are becoming the de facto tool for aerial sensing and remote inspection. In large industrial facilities, a UAV can transmit an online video stream to inspect difficult-to-access structures, such as chimneys, deposits, and towers. However, the communication range is limited, constraining th...

Wireless radio links deployed in aquatic areas (e.g., sea, rivers, lakes, estuaries) are affected by the conductive properties of the water surface, strengthening signal reflections and increasing destructive interference. Recurrent natural phenomena (e.g. tides or waves) cause shifts in water levels further impairing propagation over water surface...

Several authorsinvestigated the use of internal digital communication networks in Modular Multilevel Converters. The first works in this area keep a centralized control scheme, but they struggle to reach the fast cycle times required for achieving goodcontrol performance, specially as the number of cells increases. To reduce the network cycle time,...

Intersections are critical elements of urban traffic management and are identified as bottlenecks prone to traffic congestion and accidents. Intelligent intersection management plays a significant role in improving traffic efficiency and safety determining, among other metrics, the waiting time that vehicles incur when crossing an intersection. Thi...

This work will demonstrate a new flavor of the RA-TDMA set of protocols, namely RA-TDMAs+, which uses IEEE-802.11 (WiFi) COTS hardware in ad-hoc mode to set up a dynamic mesh network of mobile nodes with high-bandwidth. The protocol uses topology tracking to configure the TDMA frame and robust relative synchronization to define the TDMA slots witho...

Unmanned Aerial Vehicles (UAVs) in particular multirotors are becoming the {\it de facto} tool for aerial sensing and remote inspection. In large industrial facilities, a UAV can transmit an online video stream to inspect difficult to access structures, such chimneys, deposits and towers. However, the communication range is limited, constraining th...

The IEEE Time-Sensitive Networking (TSN) Task Group specifies a set of standards that enables real-time communication with predictable and bounded delays over the Ethernet. Specifically, TSN introduces a new set of so-called shapers, which regulate traffic arrival and transmission in the networks. Prominent among those are the IEEE 802.1 Qbv Time-A...

Current trends towards smart mobility aim at mitigating traffic congestion and providing intelligent and sustainable transportation. Intelligent intersection management systems are an integral part of this trend and profoundly impact urban traffic management. To this purpose, we proposed in prior work a specific Intelligent Intersection Management...

Wireless radio links deployed over aquatic areas (e.g., sea, estuaries or harbors) are affected by the conductive properties of the water surface, strengthening signal reflections and increasing interference effects. Recurrent natural phenomena such as tides or waves cause shifts in the water level that, in turn, change the interference patterns an...

Multi-lane road intersections are complex intersections with multiple-inflow/outflow lanes that are either dedicated or shared. Intelligent intersection management (IIM) strategies play a vital role in sustainable transportation by mitigating traffic congestion and reducing waiting times and associated fuel wastage. In this work, we carry out a sus...

The Symposium of Electrical and Computer Engineering (ECE), integrated in the 2021 edition of FEUP’s Doctoral Congress of Engineering is an important showcase for PhD research in this broad and vibrant area, and an opportunity for doctoral students to interact, to improve communications skills, and to gather feedback on their research work.

The centralised approach of IoT (Internet of Things) applications leveraging cloud infrastructures to address constraints at the level of end and edge nodes is no longer viable, especially for applications with hard real-time requirements and increasing AI (Artificial Intelligence) usage. This paper presents an initial analysis of the shortcomings...

Computer Vision is becoming widely used for a myriad of purposes, e.g. people counting and tracking. To execute this application in real-time, a relatively complex algorithm processes intensive data streams to identify people in a visual scenario. Although such algorithms frequently run in powerful servers on the Cloud, it is also common that they...

Networking equipment that connects households to an operator network, such as home gateways and routers, are major victims of cyber-attacks, being exposed to a number of threats, from misappropriation of user accounts by malicious agents to access to personal information and data, threatening users’ privacy and security. The exposure surface to thr...

This paper proposes network centrality as a criterion to designate a gateway or sink in real-time wireless sensor-actuator networks (WSAN). The objective is to improve network schedulability by design, particularly, by means of a centrality-driven gateway designation. To this purpose, four classical centrality metrics taken from social network anal...

This research explores the notion of network centrality as a criterion to designate a node as sink or gateway in real-time wireless sensor networks (WSN). Since centrality is a quantitative measure of how important a node is with respect to others in a given network, we propose to designate as gateway the node with the highest centrality measure. T...

This research explores the notion of network centrality as a criterion to designate a node as sink or gateway in real-time wireless sensor networks (WSN). Since centrality is a quantitative measure of how important a node is with respect to others in a given network, we propose to designate as gateway the node with the highest centrality measure. T...

Modern observation systems can be composed by heterogeneous entities (e.g., buoys, surface vehicles, onshore sensors, etc.) that rely on dependable communications for coordination and data collection, often provided by over-water radio-frequency (RF) links. In tide-affected water bodies, RF links at fixed height from the shore can experience the so...

With the scope of Industry 4.0 and the Industrial Internet of Things (IIoT), wireless technologies have gained momentum in the industrial realm. Wireless standards such as WirelessHART, ISA100.11a, IEEE 802.15.4e and 6TiSCH are among the most popular, given their suitability to support real-time data traffic in wireless sensor and actuator networks...

Conventional intersection management that allows multiple vehicles from one road at a time, e.g., Round-Robin (RR), may constitute bottlenecks in urban traffic management. Consequently, new intelligent intersection management (IIM) approaches were proposed to reduce time loss, fuel wastage, and ecological damage. IIM is also suited to take advantag...

Modern observation systems can be composed by heterogeneous entities (e.g., buoys, USVs, UAVs, onshore sensors, etc.) that rely on dependable communications for coordination and data collection, often provided by over-water radio-frequency (RF) links. In tide-affected water bodies, RF links at a fixed height from the shore can experience the so-cal...

The design of Intelligent Intersection Management (IIM) schemes for fully Autonomous Vehicles (AVs) and mixed with Human-driven Vehicles (HVs) has focused mainly on throughput maximization and users' safety. However, new IIM strategies should consider environmental factors and human health conditions in their design, given their impact on fuel wast...

Environmental pressure and technological development is finally bringing Battery operated Electric Vehicles (BEVs) to the roads. Numerous studies have shown the energy-efficiency benefits of BEVs with respect to Internal Combustion Engine Vehicles (ICEVs). However, to the best of our knowledge, the impact of traffic management policies on energy ef...

Conventional intersection management (IM) strategies that allow vehicles from one road at a time are still prone to traffic congestion, leading to time loss as well as fuel wastage and ecological damage. Therefore, we proposed an Intelligent Intersection Management Architecture (IIMA) and associated Synchronous Intersection Management Protocol (SIM...

Conventional intersection management that allows multiple vehicles from one road at a time, e.g., Round-Robin (RR), may constitute bottlenecks in urban traffic management. Consequently, new intelligent intersection management (IIM) approaches were proposed to reduce time loss, fuel wastage, and ecological damage. IIM is also suited to take advantag...

Industry 4.0 and Autonomous Driving are emerging resource-intensive distributed application domains that deal with open and evolving environments. These systems are subject to stringent resource, timing, and other non-functional constraints, as well as frequent reconfiguration. Thus, real-time behavior must not preclude operational flexibility. Thi...

The prospect scenario for wireless communications and networking technologies in aquatic environments is nowadays promising. The growing interest around this subject in the last decades has recently been accelerated due to the more powerful capabilities of a number of sensing, control and communication devices. Moored, fixed, drifting, and vehicula...

In the design of shore-to-shore and shore-to-vessel wireless links, the impact of the ray reflected on the surface is often neglected. It adds that, in some coastal areas, the geometry of the reflection changes over time due to tides. When choosing an antenna height for an inshore node, often the largest possible height is used, but this approach c...

The rising adoption of wireless technologies in the Industrial Internet of Things has stressed the need for traffic schedulability validation at system design-time to support safety and time critical streams (e.g., process control and emergency response). In this context, the demand-based schedulability tests have recently been proposed in the lite...

The performance of indoor localization techniques adopted in robot localization systems that use radio positioning is usually degraded in non-line-of-sight (NLOS) environments. In this paper, we propose a technique for estimating NLOS biases and measurement noise in distances under multidimensional scaling (MDS) based positioning with fixed nodes....

In the design of shore-to-shore and shore-to-vessel links, the impact of the signal reflections on the surface is often neglected. When choosing an antenna height for an inshore node, a typical decision is to use the largest possible height; but, this approach can lead to signal degradation. In this work, we experimentally assess the impact of surf...

In the above article [1] , the last funding acknowledgment “[…] and in part by the Research Centre Instituto de Telecomunicações under Grant UID/EEA/50008/2013.” is incorrect and outdated. The correct acknowledgment is “[…] and in part by FCT/MCTES through national funds and when applicable co-funded EU funds under the project UIDB/50008/ 2020-UI...

Vehicular ad-hoc networks (VANET) enable vehicles to exchange information on traffic conditions, dynamic status and localization, to enhance road safety and transportation efficiency. A typical VANET application is platooning, which can take advantage of exchanging information on speed, heading and position to allow shorter inter-vehicle distances...