Rui L. Aguiar

Prof. Rui L. Aguiar

Instituto de Telecomunicacoes
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orcid

Research Focus & Metrics

Academic Career Length

29Years (1998-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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21 March 2016 in IEEE Network
Verified
Journal Article
Closed access
MAMarica Amadeo
Marica Amadeo
Claudia CampoloClaudia Campolo
Claudia Campolo
JQJose Quevedo
Jose Quevedo
Daniel CorujoDaniel Corujo
Daniel Corujo
AMAntonella Molinaro
Antonella Molinaro
AVAthanasios V. Vasilakos
Athanasios V. Vasilakos
In view of evolving the Internet infrastructure, ICN is promoting a communication model that is fundamentally different from the traditional IP address-centric model. The ICN approach consists of the retrieval of content by (unique) names, regardless of origin server location (i.e., IP address), application, and distribution channel, thus enabling in-network caching/replication and content-based security. The expected benefits in terms of improved data dissemination efficiency and robustness in challenging communication scenarios indicate the high potential of ICN as an innovative networking paradigm in the IoT domain. IoT is a challenging environment, mainly due to the high number of heterogeneous and potentially constrained networked devices, and unique and heavy traffic patterns. The application of ICN principles in such a context opens new opportunities, while requiring careful design choices. This article critically discusses potential ways toward this goal by surveying the current literature after presenting several possible motivations for the introduction of ICN in the context of IoT. Major challenges and opportunities are also highlighted, serving as guidelines for progress beyond the state of the art in this timely and increasingly relevant topic.

19 February 2015 in IEEE Communications Magazine
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Journal Article
Closed access
JSJoao Soares
Joao Soares
CGCarlos Goncalves
Carlos Goncalves
BPBruno Parreira
Bruno Parreira
PTPaulo Tavares
Paulo Tavares
JCJorge Carapinha
Jorge Carapinha
Susana SargentoSusana Sargento
Susana Sargento
Deploying service functions, SFs, is an essential action for a network provider. However, the action of creating, modifying and removing network SFs is traditionally very costly in time and effort, requiring the acquisition and placement of specialized hardware devices and their interconnection. Fortunately, the emergence of concepts like cloud computing, SDN, and ultimately NFV is expected to raise new possibilities for the management of SFs with a positive impact in terms of agility and cost. From a telco viewpoint these concepts can help to both reduce OPEX and open the door to new business opportunities. In this article, we identify how téleos can benefit from the abovementioned paradigms, and explore some of the aspects that still need to be addressed in the NFV domain. We focus on two major aspects: enabling telco infrastructures to adopt this new paradigm, and orchestrating and managing SFs toward telco-ready cloud infrastructures. The technologies we describe enable a telco to deploy and manage SFs in a distributed cloud infrastructure. In this context, the Cloud4NFV platform is presented. Special attention is given to the way SFs are modeled toward cloud infrastructure resources. In addition, we explore the ability to perform service function chaining as one of the fundamental features in the composition of SFs. Finally, we describe a proof of concept that demonstrates how a telco can benefit from the described technologies.

14 November 2014 in IEEE Transactions on Vehicular Technology
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Journal Article
Closed access
KHKazi Mohammed Saidul Huq
Kazi Mohammed Saidul Huq
Shahid MumtazShahid Mumtaz
Shahid Mumtaz
JBJoanna Bachmatiuk
Joanna Bachmatiuk
JRJonathan Rodriguez
Jonathan Rodriguez
Xianbin WangXianbin Wang
Xianbin Wang
Rui L. AguiarRui L. Aguiar
Rui L. Aguiar
This paper investigates advanced energy-efficient wireless systems in orthogonal frequency-division multiple access (OFDMA) downlink networks using coordinated multipoint (CoMP) transmissions between the base stations (BSs) in a heterogeneous network (HetNet), which is adopted by Third-Generation Partnership Project (3GPP) Long-Term Evolution (LTE)-Advanced to meet International Mobile Telecommunications-Advanced targets. HetNet CoMP has received significant attention as a way of achieving spectral efficiency (SE) and energy efficiency (EE). Usually, in the literature, the total network power consumption is restricted to the sum of the power consumption of all BSs. The significance of the power consumption of the backhaul links in wireless networks is normally omitted for its trivial effect with respect to that of the radio BSs. For SE and EE analysis of HetNet CoMP, the energy and bandwidth consumption of the backhaul is considered, without which, the investigation remains incomplete. However, SE and EE are design criteria in conflict with each other, and a careful study of their tradeoff is mandatory for designing future wireless communication systems. The EE is measured as “throughput (bits) per joule,” whereas the power consumption model includes RF transmit (radiated), circuit, and backhaul power. Furthermore, a nonideal backhaul model such as a microwave link is also investigated within intra-HetNet-CoMP (inside one cell), where an implementing fiber is not feasible. An intercell interference (ICI) coordination method is also studied to mitigate ICI. At the end, a novel resource allocation algorithm is proposed-modeled as an optimization problem - which takes into account the total power consumption, including radiated, circuit, and backhaul power, and the minimum required data rate to maximize EE. Given an SE requirement, the EE optimization problem is formulated as a constrained optimization problem. The considered optimization problem is transformed into a convex optimization problem by redefining the constraint using cubic inequality, which results in an efficient iterative resource allocation algorithm. In each iteration, the transformed problem is solved by using dual decomposition with a projected gradient method. Simulations results demonstrate how backhaul has a significant impact on total power consumption and the effectiveness of the studied schemes. In addition, the results demonstrate that the proposed iterative resource allocation algorithm converges within a small number of iterations and illustrate the fundamental tradeoffs between SE and EE. Our analytical results shed light on future “green” network planning in advanced OFDMA wireless systems like those envisioned for a fifth-generation (5G) system.

1 June 2012
Verified
Conference Paper
Closed access
NKNavin Kumar
Navin Kumar
NLNuno Lourenco
Nuno Lourenco
DTDomingos Terra
Domingos Terra
LALuis Nero Alves
Luis Nero Alves
Rui L. AguiarRui L. Aguiar
Rui L. Aguiar
Emerging intelligent transportation systems (ITS) are based on several technologies. A new concept of integrating visible light communications (VLC) in ITS is introduced in this paper. VLC in ITS is a cost effective method of implementation. This paper presents a VLC broadcast system considering LED-based traffic lights. It discusses the integration of traffic light road side unit (RSUs) within the existing ITS architecture. A prototype demonstrator of the designed VLC systems is also presented. A robust modulation technique based on direct sequence spread spectrum (DSSS) sequence inverse keying (SIK) has been implemented to minimize the effect of noise sources. Experimental results show data communication range of over 40m with 200mm custom designed traffic light, even during bright sun light.

1 January 2007
Verified
Conference Paper
Closed access
EFEmanuel Fonseca
Emanuel Fonseca
AFAndreas Festag
Andreas Festag
RBRoberto Baldessari
Roberto Baldessari
Rui L. AguiarRui L. Aguiar
Rui L. Aguiar
Despite great advantages of vehicular ad hoc networks (VANETs), they also introduce challenges with respect to security and privacy. Today, people are more and more concerned about their privacy. Using unique identifiers for communication, a vehicle can easily be located and tracked. Alternatively, a technical solution to protect drivers' privacy is the use of changing pseudonyms. Existing work mainly focuses on algorithms for pseudonym change and neglect practical implications and realizability. For deployment and integration of pseudonymity into a VANET communication system, several issues need to be solved. This paper analyzes the practical challenges and proposes protocol- and implementation-related solutions necessary to turn pseudonymity support into practice. Finally, the paper concludes by means of analysis and measurements that the burden of pseudonymity can be alleviated at reasonable costs and compromises in anonymity support.

5 May 2023 in Information Systems Frontiers
Verified
Journal Article
Open access
PDF file
Catarina SilvaCatarina Silva
Catarina Silva
VCVitor A. Cunha
Vitor A. Cunha
João Paulo BarracaJoão Paulo Barraca
João Paulo Barraca
Rui L. AguiarRui L. Aguiar
Rui L. Aguiar
The advances on recent communication paradigms brings new security and privacy challenges, mainly about personal data collection by smart devices. Resource constrained devices face serious issues to run complex cryptographic algorithms. Trying to evaluate the performance impact of those algorithms in usual and common devices used in smart homes, in this paper we tested the impact of different cryptographic algorithms in low computational devices, typically used in smart devices applied in smart homes, testing different security configurations and using the two most used transport protocols (HTTP and MQTT). The experiment measures their effects on six commonly used embedded devices in IoT WSNs: ESP8622, ESP32, and Raspberry Pi (RPi) from 1 to 4. The experiment measured the power consumption, message delay, and additional message length (bytes). Moreover, the analysis was also used to model security algorithms. The experimental results from long runs (72 hours) reveal the cryptographic solution choice is significant for the message delay and additional message length.