Publications

This is a list of almost all my publications. Some recent ones may be missing as this list is kept manually. For some insight regarding the entries in this list, please check my Google Scholar Citation profile

@article

  1. Javad Zarrin, Rui L. Aguiar, and João Paulo Barraca. Manycore simulation for peta-scale system design: motivation, tools, challenges and prospects. Simulation Modelling Practice and Theory, 72():168 – 201, 2017. [ pdf ] [ BibTex ] [ +Info]

    Abstract

    Abstract The architecture design of peta-scale computing systems is complex and presents lots of difficulties to designs, as current tools lack support for relevant features of future scenarios. Novel systems must be designed with great care and tools, such as manycore architecture simulators, must be adapted accordingly. However, current simulation tools are very slow, often specific-purpose-oriented, suffer from various issues and are rarely able to simulate thousands of cores. The emergence of peta-scale systems and the upcoming manycore era brings nevertheless new challenges to computing systems and architectures, adding further difficulties and requirements on the development of the corresponding simulators. Furthermore, the design of architecture simulators for manycore systems involve methods and techniques from various interdisciplinary research areas, which in turn brings more challenges in different aspects. As system complexity grows, the growth of the simulation capacity is being outpaced (reaching the so called simulation wall). In this paper, we present the challenges for simulating future large scale manycore environments, and we investigate the adequacy of current modeling and simulation tools, methodologies and techniques. The aim of this work is to highlight how current approaches can best deal with the identified problems, smoothing the challenges of research in future peta-scale systems.

  2. Javad Zarrin, Rui L. Aguiar, and João Paulo Barraca. Elcore: dynamic elastic resource management and discovery for future large-scale manycore enabled distributed systems. Microprocessors and Microsystems, 46, Part B():221 – 239, 2016. [ pdf ] [ BibTex ] [ +Info]

    Abstract

    Abstract Large-scale computing environments (such as \{HPC\} Clusters, Grids and Clouds) provide a vast number of heterogeneous resources (such as computing, storage, data and network resources) for the users/machines with various types of accessibility (in terms of resource, data, service and application). Resource management is one of the most significant underlying challenges for efficient resource sharing and utilization in such computing environments. Designing a resource management model which can be applied and adjusted to the requirements of these different future complex computing environments is an extra challenge. This paper will address the problem of resource management for the future large-scale many-core enabled computing environments by focusing on resource allocation issues. It provides a fully decentralized generic resource management architecture which can be applied to such distributed environments. Simulation results prove that our resource management scheme is highly scalable and provides a high level of accuracy for resource allocation which has a significant impact on the overall system performance.

  3. Paulo Sousa, Muhammad Alam, Joaquim Ferreira, and Jo ao Paulo Barraca. Non-ip multi-protocol stack for vehicular communications. Mobile Networks and Applications, pages 1–15, 2016. [ pdf ] [ BibTex ] [ +Info]

    Abstract

    Wireless vehicular communications are gaining momentum, mainly to improve road safety through the use of cooperative systems. Such visionary cooperative applications are based on recently established families of standards, notably the IEEE Wireless Access for Vehicular Environment (WAVE) and the ETSI ITS G5. Despite some relevant differences, both family of standards share the same physical and MAC layers, described in the IEEE 802.11:2012 - amendment 6, also know as IEEE 802.11p. Due to the characteristics of the wireless communications in vehicular environment, e.g., high-speed mobility causing unpredictable time-varying changes in connectivity, IP protocols are not suitable for safety communications as they require channel scanning, authentication and association under strict time limits. Safety vehicular communications rely, instead on non-IP protocols, either the WAVE Short Message Protocol (WSMP) or the FAST Network and Transport Protocol (FNTP). In this paper, we explore some of the challenges of implementing such protocols, and designed an architecture for a stack capable of handling both standards. The proposed architecture, including the communication and transport layers of the stack, was implemented in a custom ETSI ITS G5 compliant platform (IT2S), and its performance was assessed using a prototype.

  4. Rasool Sadeghi, João Paulo Barraca, and Rui L. Aguiar. A survey on cooperative mac protocols in ieee 802.11 wireless networks. Wireless Personal Communications, pages 1–25, 2016. [ pdf ] [ BibTex ] [ +Info]

    Abstract

    The concept of cooperative communication appears as a beneficial method that can address key challenges faced by wireless networks. Cooperative techniques in IEEE 802.11 MAC protocols have thus received significant attention both in theoretical and practical aspects. In this survey article, we provide an overview of existing research on cooperative MAC protocols in the IEEE 802.11 standard. We specially focus on protocol's behavior and propose a novel architectural model for cooperation. We present a classification of cooperative relay based MAC protocols, along model desired categories, and review representative cooperative protocols for 802.11. We further evaluate the operational issues of cooperative protocols in term of architecture, compatibility and complexity.

  5. Javad Zarrin, Rui L. Aguiar, and João Paulo Barraca. Dynamic, scalable and flexible resource discovery for large-dimension many-core systems. Future Generation Computer Systems, ():–, 2015. [ pdf ] [ BibTex ] [ +Info]

    Abstract

    Abstract Future large scale systems will execute novel operating systems running across many chips with many cores. In this highly distributed environment, resource discovery is an important building block. Resource discovery aims to match the application’s demands to the existing (distributed) resources, by discovering and finding resources at run-time, and then selecting the best resource that matches the application running requirements. The main contribution of this paper is the design and evolution of a highly scalable, highly flexible, resource discovery model for such heterogeneous environments. The model is based on self-organizing processing resources in the system according to a hierarchical resource description where each group of resources has a local directory that collects and keeps the information of the underlying resource members (cores) in different layers. Operationally, at each layer, it consists of a peer-to-peer architecture of modules that, by interacting with each other, provide a global view of the resource availability in a large, dynamic and heterogeneous distributed environment. The proposed resource discovery model provides the adaptability and flexibility to perform complex querying by supporting a large set of significant querying features (such as multi-dimensional, range and aggregate querying) while supporting exact and partial matching, both for static and dynamic object contents. The paper demonstrates by simulation how the proposed model can deal with issues such as scalability, efficiency and adaptability of resource discovery in future many-core systems which are the major challenges in the current state of the art. The simulation shows that the proposed resource discovery model can be applied to arbitrary scales of dynamicity, both in terms of complexity and of scale, positioning this proposal as a good architecture for future many-core systems.

  6. J. Soares, C. Goncalves, B. Parreira, P. Tavares, J. Carapinha, J.P. Barraca, R.L. Aguiar, and S. Sargento. Toward a telco cloud environment for service functions. Communications Magazine, IEEE, 53(2):98–106, Feb 2015. doi:10.1109/MCOM.2015.7045397. [ pdf ] [ BibTex ] [ +Info]

    Abstract

    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.

  7. Mário Antunes, João Paulo Barraca, Diogo Gomes, Paulo Oliveira, and Rui L. Aguiar. Smart cloud of things: an evolved iot platform for telco providers. Journal of Ambient Wireless Communications and Smart Environments (AMBIENTCOM), 1(1):1 – 24, 2015. [ pdf ] [ BibTex ]
  8. Rui L. Aguiar, Diogo Gomes, João Paulo Barraca, and Nuno Lau. Cloudthinking as an intelligent infrastructure for mobile robotics. Wireless Personal Communications, 76(2):231–244, 2014. [ pdf ] [ BibTex ] [ +Info]

    Abstract

    Mobile robotics is a transforming field that presents a varying set of challenges. The discussion on the autonomy of (self-powered) robots is not settled, and as the communication infrastructure evolves, centralized concepts become more attractive over distributed concepts. This paper presents the CloudThinking architecture applied to intelligent cloud-based robotic operation. CloudThinking offloads most of complex robotic tasks to a central cloud, which retrieves inputs from the environment as a whole in order to instruct the robots to perform its actions. CloudThinking is a natural approach to the orchestration of multiple specialized robotic systems, defining the best mechanisms for reaching a goal. Furthermore, this architecture provides a set of automatic features which can be useful for application developers. These features can fully exploit novel cloud tools development as it becomes available, providing a time-resilient infrastructure of easy upgrade. The resulting approach has the potential to create a different set of market for robotic application developers.

  9. Alfredo Matos, Miguel Ponce de Leon, Rui Ferreira, and João Paulo Barraca. Prose: survey on requirements for hosting open source software projects. SUCRE CloudSource Magazine, April 2013. [ pdf ] [ BibTex ] [ +Info]

    Abstract

    Widespread use of free/libre/open source software (FLOSS) in European funded projects is vital to innovation transfer, but often, such software doesn’t enter general use. Legal issues, lack of business drivers, incomplete documentation and lack of knowledge about FLOSS are some of the most common reasons for this. PROSE, an EU-funded project tasked with promoting FLOSS, aims to provide a common cloud platform on which open source projects can be hosted and information shared. But how would such a platform work? And what would be its main requirements and features? PROSE turned to ICT FP7 participants for answers.

  10. João Paulo Barraca, Rasool Sadeghi, and Rui L. Aguiar. Collaborative Relaying Strategies in Autonomic Management of Mobile Robotics. International Journal on Wireless Personal Communications, 01:22, January 2013. (waiting publication). [ pdf ] [ BibTex ] [ +Info]

    Abstract

    Mobile robotics is a field that presents a surprising set of challenges to communications. One concept that can result in radically different solutions in mobile robotics is that of collaborative and cooperative communications. Cooperative techniques in wireless networks can enhance the performance of communication especially in cases where a small number of robots can be used to aid the establishment of reliable and efficient communication links. In this paper, we present a scenario for hybrid mobile robotics, where a small number of carriers are able to reposition nodes according to communication needs. We developed a common information management layer in order to coordinate cooperation (including communication aspects) between all units (information nodes and robots) according to high level self-established policies. We select IEEE 802.11 technology as the technology for the communication infrastructure and explore its potential for cooperative mobile environments in terms of power and spectrum efficiency presenting the rules required to reconfigure such a mobile robotic environment.

  11. Rasool Sadeghi, João Paulo Barraca, and Rui L. Aguiar. Energy Efficiency and Capacity Modeling for Cooperative Cognitive Networks. Journal of Green Engineering, 2012. [ pdf ] [ BibTex ] [ +Info]

    Abstract

    Cooperative relaying has recently appeared as one of the widely recognized features for future wireless communication systems. The great potential of cooperative communication in increasing system capacity and enhancing power efficiency has attracted large efforts over the last few years. In this paper, we propose a Cooperation Loop as a reference model for all algorithms in relay based cooperative wireless networks. Using this model, we discuss cooperative relay based protocols in IEEE 802.11 standards and limits posed to cognitive approaches. We show the potential location area of relay nodes as well as the performance bounds of capacity gain, delay and power efficiency achieved in relay based scenarios for any cooperative cognitive algorithms.

  12. Rasool Sadeghi, João Paulo Barraca, and Rui L. Aguiar. Cooperative performance bounds of Wireless Local Area Networks. Wireless Personal Multimedia Communications (WPMC), 2011 14th International Symposium on, pages 1–5, October 2011. [ pdf ] [ BibTex ] [ +Info]

    Abstract

    In a Wireless Local Area Network (WLAN), capacity gain and delay reduction play a crucial role in system performance. In this paper, we focus on performance improvements when WLANs exploit the concept of cooperation among nodes. We propose a geometrical model to determine the potential location area of relay nodes. The analytical results are validated by simulation. Performance bounds and average of capacity gain and delay ratio are studied for different IEEE 802.11 standards.

    URL: http://ieeexplore.ieee.org/xpl/articleDetails.jsp?arnumber=6081533

  13. Luís Couto, João Paulo Barraca, Susana Sargento, and Rui L. Aguiar. FastM: Design and Evaluation of a Fast Mobility Mechanism for Wireless Mesh Networks. International Journal On Advances in Networks and Services, 2(9):273–285, February 2009. [ pdf ] [ BibTex ] [ +Info]

    Abstract

    Although there is a large volume of work in the literature in terms of mobility approaches for Wireless Mesh Networks, usually these approaches introduce high latency in the handover process and do not support realtime services and applications. Moreover, mobility is decoupled from routing, which leads to inefficiency to both mobility and routing approaches with respect to mobility. In this paper we present a new extension to proactive routing protocols using a fast mobility extension, FastM, with the purpose of increasing handover performance in Wireless Mesh Networks. With this new extension, a new concept is created to integrate information between neighbor wireless mesh routers, managing locations of clients associated to wireless mesh routers in a certain neighborhood, and avoiding packet loss during handover. The proposed mobility approach is able to optimize the handover process without imposing any modifications to the current IEE 802.11 MAC protocol and use unmodified clients. Results show the improved efficiency of the proposed scheme: metrics such as disconnection time, throughput, packet loss and control overhead are largely improved when compared to previous approaches. Moreover, these conclusions apply to mobility scenarios, although mobility decreases the performance of the handover approach, as expected.

    URL: http://hdl.handle.net/10773/8085

  14. P. Antoniadis, B. Le Grand, A. Satsiou, L. Tassiulas, Rui L. Aguiar, João Paulo Barraca, and S. Sargento. Community Building over Neighborhood Wireless Mesh Networks. IEEE Technology and Society Magazine, 27(1):48–56, March 2008. [ pdf ] [ BibTex ] [ +Info]

    Abstract

    The fourth generation (4G) network paradigm has long been sought. A user-centric vision for such "always best connected" next-generation 4G networks is neighborhood wireless mesh networks (WMNs). In this context, the vision for the formation of WMNs reflects the trade-off between the immediate self-interest of the user, and the user's need for social contacts. Notably, users would be required to pool their resources in order to support the creation and operation of the underlying communication network (participating at all physical, access, and network layers), but also for the service provision on top of it. We argue that the design of communities suitable for this environment will encourage users to participate, enable trustworthy network creation, and provide a social layer, which can be exploited in order to design cross-layer incentive mechanisms that will further encourage users to share their resources and cooperate at lower layers.

    URL: http://ieeexplore.ieee.org/xpl/articleDetails.jsp?arnumber=4468734

  15. Miguel Almeida, Rafael Sarrô, JoãoPaulo Barraca, Susana Sargento, and Rui L Aguiar. Experimental Evaluation of the Usage of Ad Hoc Networks as Stubs for Multiservice Networks. EURASIP Journal on Wireless Communications and Networking, 2007(1):39, jan 2007. [ pdf ] [ BibTex ] [ +Info]

    Abstract

    This paper describes an experimental evaluation of a multiservice ad hoc network, aimed to be interconnected with an infras- tructure, operator-managed network. This network supports the efficient delivery of services, unicast and multicast, legacy and multimedia, to users connected in the ad hoc network. It contains the following functionalities: routing and delivery of unicast and multicast services; distributed QoS mechanisms to support service differentiation and resource control responsive to node mobility; security, charging, and rewarding mechanisms to ensure the correct behaviour of the users in the ad hoc network. This paper experimentally evaluates the performance of multiple mechanisms, and the influence and performance penalty introduced in the network, with the incremental inclusion of new functionalities. The performance results obtained in the different real sce- narios may question the real usage of ad-hoc networks for more than a minimal number of hops with such a large number of functionalities deployed.

    URL: http://dx.doi.org/10.1155/2007/62967

  16. João Girão, Bernd Lamparter, Dirk Westhoff, Rui L. Aguiar, and João Paulo Barraca. Implementing Charging in Mobile Ad-hoc Networks. Electrónica e Telecomunicações, 2004. [ pdf ] [ BibTex ] [ +Info]

    Abstract

    In order to keep up with new networking needs, it becomes necessary to adopt mechanisms for charging network usage in a universal way. The Secure Charging Protocol (SCP) aims at answering this complex authentication, authorization, accounting and charging (AAAC) problem, and provides a view based on a different business model, one that has been adjusted to cope with technological changes. This document discusses SCP as a possible solution to the AAAC problems in MANETs and addresses the improvements made to this protocol in terms of Quality of Service (QoS) and User Interfaces. An implementation of this protocol on PDAs is also described.

  17. Diogo Gomes, João Paulo Barraca, and Nuno Sénica. System to Support the Organization and Management of Scientific Conferences (CoW - Conference on the Web). Electrónica e Telecomunicações, 2003. [ pdf ] [ BibTex ] [ +Info]

    Abstract

    This article presents a software package developed to help in the organization and management of Scientific Conferences on the Web (CoW). This software was developed by students of the last year of the Computers and Telematics Engeneering Degree in the aim of the Multimedia Tools and Applications 5th year optional discipline.

  18. João Paulo Barraca and Nuno João Sénica. Síntese e implementação de circuitos digitais reconfiguráveis dinamicamente (projecto 4). Electrónica e Telecomunicações, 2003. [ pdf ] [ BibTex ] [ +Info]

    Abstract

    The paper presents the results of the project proposed to the authors (who are the 4th year students of LECT) and shows how the specified problem has been solved. The description of the project and the basic requirements have been considered in the papers [1,2].

@inproceedings

  1. V. Santos, João P. Barraca, and Diogo Gomes. Secure decentralized iot infrastructure. In 2017 Wireless Days, 173–175. March 2017. doi:10.1109/WD.2017.7918137. [ pdf ] [ BibTex ] [ +Info]

    Abstract

    Despite many Internet of Things (IoT) Infrastructures having been implemented in recent years, none of them is truly prepared for a global deployment, where failure tolerance and scalability are an essential requirement. This article presents an alternative concept for IoT Infrastructures, which focuses on enhancing the traditional centralized architecture, usually operated by a single entity, into a decentralized architecture featuring multiple business roles. We propose a dynamic and self-configurable infrastructure on top of a structured Peer-to-Peer network. In addition, a set of communication protocols are provided in order to support heterogeneous devices, as well as data access, streaming and persistence. It is also an important focus of our proposal to have mechanisms that guarantee the privacy and security of the information flow and storage.

  2. João Rodrigues, João Paulo Barraca, and André Zúquete. Data security mechanisms for iot platforms. In Proc. 8th Informatics Symposium (INFORUM 2016), volume. sep 2016. [ pdf ] [ BibTex ]
  3. Swaminathan Natarajan, Domingos Barbosa, Joao P. Barraca, Alan Bridger, Subhrojyoti R. Choudhury, Matteo Di Carlo, Mauro Dolci, Yashwant Gupta, Juan Guzman, Lize Van den Heever, Gerhard Le Roux, Mark Nicol, Mangesh Patil, Riccardo Smareglia, Paul Swart, Roger Thompson, Sonja Vrcic, and Stewart Williams. Ska telescope manager (tm): status and architecture overview. In Proc. SPIE, volume 9913, 991302–991302–10. 2016. [ pdf ] [ BibTex ] [ +Info]

    Abstract

    The SKA radio telescope project is building two telescopes, SKA-Low in Australia and SKA-Mid in South Africa respectively. The Telescope Manager is responsible for the observations lifecycle and for monitoring and control of each instrument, and is being developed by an international consortium. The project is currently in the design phase, with the Preliminary Design Review having been successfully completed, along with re-baselining to match project scope to available budget. This report presents the status of the Telescope Manager work, key architectural challenges and our approach to addressing them.

  4. Helder Moreira, Gonçalo Correia, Manuel Silva, André Marques, João Paulo Barraca, Luis Alves, Pedro Fonseca, and Nuno Lourenço. Smartlighting: a platform for intelligent building management. In Proc. 8th Informatics Symposium (INFORUM 2016), volume. sep 2016. [ pdf ] [ BibTex ] [ +Info]

    Abstract

    This work proposes a solution to endow buildings with efficiency and intelligence, exploiting the advantages of Complex Event Processing (CEP) techniques and Internet of Things (IoT) principles. This combination allows efficient management of the entire infrastructure, and in particular enabling lighting to be tailored to users’ needs. We validate this solution through a prototype implementation, based on wireless sensors and actuator networks that interact with the environment, using standard lightweight protocols designed for IoT. The prototype is based on high performance and real time platforms, and complex methods for analysis of large streams of data. The implementation is applied to a real world scenario, and will be used as the standard solution for management and automation of an existing building.

  5. V. A. Cunha, I. D. Cardoso, J. P. Barraca, and R. L. Aguiar. Policy-driven vcpe through dynamic network service function chaining. In 2016 IEEE NetSoft Conference and Workshops (NetSoft), 156–160. June 2016. doi:10.1109/NETSOFT.2016.7502463. [ pdf ] [ BibTex ] [ +Info]

    Abstract

    Virtual CPEs address the low agility, slow time-to-market and high costs (of development, deployment and support) that are inheritable to traditional CPEs. They take advantage of the economics of Cloud Computing and the ability to run Virtual Network Functions in a general computing platform to build richer services, with faster development and deployment times, all whilst reducing costs. When coupled together with Service Function Chaining and the ability to build/enter chains dynamically, an opportunity arises to enhance this system by making the whole vCPE's functionality policy-driven. We will start by constructing the vCPE within an OpenSource cloud platform (OpenStack), which will have dynamic SFC capablities added through own extensions. Then we will make the traffic classification through a DPI (ntop's nDPI), which will mark flows according to a configurable policy (REST interface) that will determine which service chain that flow must follow. Some virtual functions within a chain may trigger events (such as reaching the traffic quota for a certain service), being the policy immediately enforced at the VNFs and an “on-the-fly” policy change possible through the REST interface (for instance, change the throttle amount to a given application traffic). A live Proof-of-Concept was made which allowed real devices to connect to the vCPE.

  6. Domingos Barbosa, João Paulo Barraca, Dalmiro Maia, Bruno Carvalho, Jorge Vieira, Paul Swart, Gerhard Le Roux, Swaminathan Natarajan, Arnold van Ardenne, and Luis Seca. Power monitoring and control for large scale projects: ska, a case study. In Proc. SPIE, volume 9910, 99100J–99100J–10. 2016. [ pdf ] [ BibTex ] [ +Info]

    Abstract

    Large sensor-based science infrastructures for radio astronomy like the SKA will be among the most intensive datadriven projects in the world, facing very high demanding computation, storage, management, and above all power demands. The geographically wide distribution of the SKA and its associated processing requirements in the form of tailored High Performance Computing (HPC) facilities, require a Greener approach towards the Information and Communications Technologies (ICT) adopted for the data processing to enable operational compliance to potentially strict power budgets. Addressing the reduction of electricity costs, improve system power monitoring and the generation and management of electricity at system level is paramount to avoid future inefficiencies and higher costs and enable fulfillments of Key Science Cases. Here we outline major characteristics and innovation approaches to address power efficiency and long-term power sustainability for radio astronomy projects, focusing on Green ICT for science and Smart power monitoring and control.

  7. Domingos Barbosa, João P. Barraca, Bruno Carvalho, Dalmiro Maia, Yashwant Gupta, Swaminathan Natarajan, Gerhard Le Roux, and Paul Swart. A cyber infrastructure for the ska telescope manager. In Proc. SPIE, volume 9913, 99130K–99130K–12. 2016. [ pdf ] [ BibTex ] [ +Info]

    Abstract

    The Square Kilometre Array Telescope Manager (SKA TM) will be responsible for assisting the SKA Operations and Observation Management, carrying out System diagnosis and collecting Monitoring and Control data from the SKA subsystems and components. To provide adequate compute resources, scalability, operation continuity and high availability, as well as strict Quality of Service, the TM cyber-infrastructure (embodied in the Local Infrastructure - LINFRA) consists of COTS hardware and infrastructural software (for example: server monitoring software, host operating system, virtualization software, device firmware), providing a specially tailored Infrastructure as a Service (IaaS) and Platform as a Service (PaaS) solution. The TM infrastructure provides services in the form of computational power, software defined networking, power, storage abstractions, and high level, state of the art IaaS and PaaS management interfaces. This cyber platform will be tailored to each of the two SKA Phase 1 telescopes (SKA_MID in South Africa and SKA_LOW in Australia) instances, each presenting different computational and storage infrastructures and conditioned by location. This cyber platform will provide a compute model enabling TM to manage the deployment and execution of its multiple components (observation scheduler, proposal submission tools, MandC components, Forensic tools and several Databases, etc). In this sense, the TM LINFRA is primarily focused towards the provision of isolated instances, mostly resorting to virtualization technologies, while defaulting to bare hardware if specifically required due to performance, security, availability, or other requirement.

  8. Carla V. Leite, João Paulo Barraca, Domingos Barbosa, William Garnier, and Mathieu Isidro. When science fiction turns to reality: square kilometre array (ska), the largest radio telescope ever imagined. In International Conference Cinema - Art, Technology, Communication 2015. July 2015. [ pdf ] [ BibTex ]
  9. I. Duarte Cardoso, J.P. Barraca, C. Goncalves, and R.L. Aguiar. Seamless integration of cloud and fog networks. In Network Softwarization (NetSoft), 2015 1st IEEE Conference on, 1–9. April 2015. doi:10.1109/NETSOFT.2015.7116140. [ pdf ] [ BibTex ] [ +Info]

    Abstract

    This work provides a way to merge Cloud Computing infrastructures with traditional or legacy network deployments, leveraging the best in both worlds and enabling a logically centralized control for it. A solution is proposed to extend existing Cloud Computing software stacks so they are able to manage networks outside the Cloud Computing infrastructure, by extending the internal, virtualized network segments. This is useful in a variety of use cases such as incremental Legacy to Cloud network migration, hybrid virtual/traditional networking, centralized control of existing networks, bare metal provisioning, and even offloading of advanced services from typical home gateways into the operator. By using what is called External Drivers, any organization can develop their own driver to support new, specific networking equipment. Our concept solution is prototyped on top of OpenStack, including changes to the API, command line interface and other mechanisms. Test results indicate that there are low penalties on latency and throughput, and that provisioning times are reduced in comparison with similar maintenance operations on traditional computer networks.

  10. B. S. Cruz and João Paulo Barraca. Ims centric communication supporting webrtc endpoints. In 2015 IEEE Symposium on Computers and Communication (ISCC), 732–737. July 2015. doi:10.1109/ISCC.2015.7405601. [ pdf ] [ BibTex ]
  11. Luis Nero Alves, João Paulo Barraca, and Rui L. Aguiar. Benefits of metering and intelligent control in energy savings of public street ligthing - ua smart campus use case. In Information Technology for Energy 2015 (IT4Energy) Workshop. April 2015. [ pdf ] [ BibTex ]
  12. Javad Zarrin, Rui L. Aguiar, and João Paulo Barraca. A self-organizing and self-configuration algorithm for resource management in service-oriented systems. In Computers and Communication (ISCC), 2014 IEEE Symposium on, 1–7. June 2014. doi:10.1109/ISCC.2014.6912524. [ pdf ] [ BibTex ] [ +Info]

    Abstract

    With the ever increasing deployment of service oriented distributed systems in large-scale and heterogeneous computing environments, clustering and communication overlay topology design has become more and more important to address several challenging issues and conflicting requirements, such as efficient scheduling and distribution of services among computing resources, reducing communication cost between services, high performance service and resource discovery while considering both inter-service and inter-node properties and also increasing the load distribution and the load balance. In this paper, a four-stage hierarchical clustering algorithm is proposed which automates the process of the optimally composing communicating groups in a dynamic way while preserving the proximity of the nodes. The simulation results show the performance of the algorithm with respect to load balance, scalability and efficiency.

  13. R. Sadeghi, J.P. Barraca, and R.L. Aguiar. Cooperation metric for ieee 802.11 wireless networks. In New Technologies, Mobility and Security (NTMS), 2014 6th International Conference on, 1–5. March 2014. doi:10.1109/NTMS.2014.6814013. [ pdf ] [ BibTex ] [ +Info]

    Abstract

    A key design issue in relay based cooperative wireless networks is the design of an appropriate metric for relay selection algorithms. In most cooperative protocols designed for IEEE 802.11 networks, the relay selection metric is based on reducing the transmission delay of relay links. The bandwidth efficiency provided by this metric is beneficial for applications communicating at high data rate, however not all applications will benefit from this simple approach. In this paper, a novel cooperative metric is proposed, which in addition to bandwidth, also considers link reliability and link stability, especially useful in mobile scenarios, and for time sensitive service applications. The proposed metric is applied to the well-known CoopMAC protocol. Simulation results indicate a strong correlation between network performance and proposed cooperative metric.

  14. J.P. Barraca, L.N. Alves, and M. Figueiredo. Electronic shelf labeling employing visible light communication concepts. In Communication Systems, Networks Digital Signal Processing (CSNDSP), 2014 9th International Symposium on, 1017–1022. July 2014. doi:10.1109/CSNDSP.2014.6923978. [ pdf ] [ BibTex ] [ +Info]

    Abstract

    This paper discusses the usage of visible light communication concepts for Electronic Shelf Labeling Devices (ESLD), using unmodified smart phones. Visible light communication enables novel and interesting approaches to the design of these devices, able to address application scenarios that have not yet been explored. Amongst these novel approaches, it is worthwhile highlighting the feasibility to offer easy integration of social networking concepts, and the inherent ability to explore communication means supported by the lighting installation. The achieved results show that these novel electronic shelf labeling devices are able to offer good quality of service support, with nearly optimal bit error rates under normal illumination levels.

  15. D. Barbosa, J.P. Barraca, A.-J. Boonstra, R. Aguiar, A. van Ardenne, J. De Santander-Vela, and L. Verdes-Montenegro. A sustainable approach to large ict science based infrastructures; the case for radio astronomy. In Energy Conference (ENERGYCON), 2014 IEEE International, 668–674. May 2014. doi:10.1109/ENERGYCON.2014.6850498. [ pdf ] [ BibTex ] [ +Info]

    Abstract

    Large sensor-based infrastructures for radio astronomy will be among the most intensive data-driven projects in the world, facing very high power demands. The geographically wide distribution of these infrastructures and their associated processing High Performance Computing (HPC) facilities require Green Information and Communications Technologies (ICT): a combination is needed of low power computing, power and byte efficient data storage, local data services, Smart Grid power management, and inclusion of Renewable Energies. Here we outline the major characteristics and innovation approaches to address power efficiency and long-term power sustainability for radio astronomy projects, focusing on Green ICT for science.

  16. Mário Antunes, João Paulo Barraca, Diogo Gomes, Paulo Oliveira, and RuiL. Aguiar. Unified platform for m2m telco providers. In Ramón Hervás, Sungyoung Lee, Chris Nugent, and José Bravo, editors, Ubiquitous Computing and Ambient Intelligence. Personalisation and User Adapted Services, volume 8867 of Lecture Notes in Computer Science, 436–443. Springer International Publishing, 2014. [ pdf ] [ BibTex ] [ +Info]

    Abstract

    Although many environments are powered by M2M solutions, users do not have a simple way to gather their collective knowledge and program devices’ behaviour. Also, Telco providers still lack proper components for enabling integrated services over their networks. We present the final architecture of the APOLLO project, which delivers a enhanced M2M platform encompassing sensors, management and applications platform for a major Telco provider. APOLLO builds on top of ETSI M2M specifications and rich service execution environments providing easy orchestration of services to end-users.

  17. Alfredo Matos, Miguel Ponce de Leon, Rui Ferreira, and João Paulo Barraca. An open source software forge for european projects. In Proceedings of the Workshop on Open Source and Design of Communication, OSDOC '13, 41–45. New York, NY, USA, 2013. ACM. [ pdf ] [ BibTex ] [ +Info]

    Abstract

    {Open Source is an increasingly interesting vehicle for dissemination of project results within the R&D andICT FP7 communities. PROSE, an FP7 ICT project, is promoting open source adoption by creating a software forge that provides project management, source code hosting, and development support for the ICT and European open source projects. In this paper we present the key requirements for a software forge resulting from a public consultation of projects in the European space, and the corresponding instantiation of an open source software forge, publicly available at opensourceprojects.eu. We also discuss the relevance of a centralized collaboration platform for European projects, and the value presented by such an approach as opposed to current source code repositories.}

    URL: http://doi.acm.org/10.1145/2503848.2503857

  18. Bruno Santos, João Paulo Barraca, and Rui L. Aguiar. Asynchronous design pattern for many-core and cloud operating systems. In European Network of Excellence on High Performance and Embedded Architecture and Compilation. January 2012. [ pdf ] [ BibTex ] [ +Info]

    Abstract

    One of the key aspects for many-core and cloud operating systems is message passing communication. The networking aspect of this mechanism requires a high degree of concurrency to handle communicating with thousands of cores simultaneously in an efficient and scalable manner. Non-blocking interfaces allows us to efficiently use a core and gives us concurrency without multiple threads, this also minimizes context switch. We developed an asynchronous design pattern for operating systems written in C++. The framework uses only C++ language features (template metaprogramming), thus not requiring a custom compiler. The pattern provides a framework to develop and use asynchronous interfaces based on completion handlers. As the name implies, a completion handler is executed when the operation completes. The framework also provides queuing mechanism to serialize execution of handlers for synchronization purposes.

    URL: http://hdl.handle.net/10773/7960

  19. Alexander Pleszko, João Paulo Barraca, Joaquim Ferreira, and Pedro Goncalves. Multiplatform management of a Hard Real-Time Ethernet Switch. In IEEE Globecom Workshops (GC Wkshps), 829–834. 2012. doi:10.1109/GLOCOMW.2012.6477683. [ pdf ] [ BibTex ] [ +Info]

    Abstract

    The Hard Real-Time Ethernet Switch (HaRTES) allows using the same network to handle multiple traffic flows, without compromising the performance of real-time applications. Furthermore, it also provides flexible and on-line scheduling techniques with admission control capabilities, thus real-time communications flows can be added, removed and updated online with strict temporal isolation. However, HaRTES lacked a standard management interface to configure its parameters and view its status. This paper describes a multiprotocol (SNMP and NETCONF) management interface design, and implementation. It also presents a preliminary validation of the two management technologies.

  20. Gustavo Pires, Mário Antunes, Daniel Corujo, Diogo Gomes, João Paulo Barraca, and Rui L. Aguiar. Architecture for orchestration of M2M services. In 12th Conferência sobre Redes de Computadores. 2012. [ pdf ] [ BibTex ] [ +Info]

    Abstract

    The past few years, miniaturization has allowed us to imbue computers into everyday devices. This in turn has enabled these devices to communicate with each other, and in doing so, allows us to collect a wealth of information, more accurately and with greater availability than ever before. This phenomenon is known as the Internet of Things. It allows smart environments to truly behave in an intelligent manner by using information collected from the devices mentioned above. However, it’s necessary to model how the gathered data will influence the behavior of a smart environment. This open problem can be approached as a machine to machine (M2M) orchestration. In this paper we present a new architecture for M2M orchestration. This new architecture will be based around a platform that creates orchestration processes through a graphical interface. Through this interface a business process execution language (BPEL) service will be made and deployed on an enter- prise service bus (ESB). Alongside this, we are also developing a collection of services that will be used for the purposes of implementing a smart environment.

  21. João Martins, João Paulo Barraca, Diogo Gomes, and Rui L. Aguiar. Experimentation made easy with the amazing panel. In Proceedings of the seventh ACM international workshop on Wireless network testbeds, experimental evaluation and characterization, WiNTECH '12, 11–18. New York, NY, USA, 2012. ACM. [ pdf ] [ BibTex ] [ +Info]

    Abstract

    Experimental testbeds for evaluating solutions in computer networks, are today required as a complement to simulation and emulation. As these testbeds become larger, and accessible to a broader universe of the research community, dedicated management tools become mandatory. These tools ease the complex management of the testbed specific resources, while providing an environment for researchers to define their experiments with large flexibility. While there are currently several management tools, the research community is still lacking tools that smooth the experimentation workflow. These were key aspects that we considered when developing the management infrastructure for our wireless testbed(AMazING). We developed a experimentation support framework supported by an attractive GUI, automation and scripting capabilities, as well as experiment versioning and integrated result gathering and analysis.

    URL: http://doi.acm.org/10.1145/2348688.2348693

  22. João Martins, João Paulo Barraca, Diogo Gomes, and Rui L. Aguiar. Demonstrating the amazing panel. In Proceedings of the Seventh ACM International Workshop on Wireless Network Testbeds, Experimental Evaluation and Characterization, WiNTECH '12, 89–90. New York, NY, USA, 2012. ACM. [ pdf ] [ BibTex ]
  23. Carlos Gonçalves, David Cunha, Pedro Neves, Pedro Nuno Sousa, João Paulo Barraca, and Diogo Gomes. Towards a Cloud Service Broker for the Meta Cloud. In 12th Conferência sobre Redes de Computadores. 2012. [ pdf ] [ BibTex ] [ +Info]

    Abstract

    Cloud Computing provides computing resources, middleware and (web-based) software on an on-demand basis. This model helps customers saving costs and allows access to the latest technology. With the exponential growth of IT companies offering cloud services, deploying applications to the cloud has become a complex task to engage. Almost each and every provider has its own terminology, providers do not share the same (or even similar) API, and costs of operation greatly diverge according to provider, region or availability. This paper propounds a Cloud Service Broker (CSB), and describes an early prototype, where users are, intelligently and autonomously, aid to deploy, manage, monitor and migrate their applications in a cloud of clouds. A single API is required to orchestrate the whole process in tandem with two truly decoupled managers: a Platform as a Service Manager (PaaS Manager) and an Infrastructure as Service Manager (Iaas Manager). Users also interact with the CSB through a Web portal and a command-line interface.

  24. Rasool Sadeghi, João Paulo Barraca, and Rui L. Aguiar. Metrics for optimal relay selection in cooperative wireless networks. In Proceedings of the 22nd International Symposium on Personal Indoor and Mobile Radio Communications (PIMRC), 278 –283. September 2011. [ pdf ] [ BibTex ] [ +Info]

    Abstract

    A key design issue in relay based cooperative wireless networks is the metrics used for relay selection. Internal operational parameters and network sensing parameters are two categories recently considered as decision factors for cooperation strategies. We focus on the impact of these potential sensing parameters as indicators of the effective cooperation, from the perspective of the network layer, namely: movement, medium access delay and medium delay ratio. Simulation results indicate a strong correlation between network performance and the proposed cooperative metrics. Novel solutions for cooperation should take these metrics into consideration in order to provide better network performance.

    URL: http://ieeexplore.ieee.org/xpl/articleDetails.jsp?tp=\&arnumber=6139966

  25. João Paulo Barraca, Diogo Gomes, and Rui L. Aguiar. AMazING-Advanced Mobile wireless playGrouNd. In 6th International ICST Conference on Testbeds and Research Infrastructures for the Development of Networks and Communities (TRIDENTCOM), volume 46 of Lecture Notes of the Institute for Computer Sciences, Social Informatics and Telecommunications Engineering (LNICST), 219–230. Institute for Computer Sciences, Social Informatics and Telecommunications Engineering, Springer Verlag, May 2011. [ pdf ] [ BibTex ] [ +Info]

    Abstract

    We describe a wireless testbed composed of 24 wireless nodes that can be used to perform a broad range of studies in the area of next generation networks. This paper addresses the difficulties and constrains faced by the authors throughout the deployment process of such testbed. Flexibility and controllability were key concerns driving the testbed design. The testbed can be remotely managed through a series of remotely accessible web services performing low level management. Validation results are presented, showing the interference levels of the testbed as well as its maximum throughput capabilities.

    URL: http://dx.doi.org/10.1007/978-3-642-17851-118

  26. João Paulo Barraca, Alexandre Brito, and Rui L. Aguiar. Network Interfaces Flying over IP Networks. In Proceedings of the 2011 IEEE Symposium on Computers and Communications, ISCC '11, 10016–10021. IEEE Computer Society, June 2011. [ pdf ] [ BibTex ] [ +Info]

    Abstract

    We propose a novel method to export both interface control and data planes across different hosts, effectively enabling hardware specific control of network interfaces over the Internet, or from a host to its virtualized guests. Our solution is a major step towards distributed environments of heterogeneous communication systems, particularly relevant in the scope of custom system composition, remote development and testing, and is especially relevant when considering embedded or geographically constrained devices. Results obtained by our prototype implementation validate the effectiveness of the solution. We present a preliminary characterization of its impact, when considering traffic generation applications, when applied over an IEEE 802.11g communication medium.

    URL: http://ieeexplore.ieee.org/xpl/articleDetails.jsp?arnumber=5983975

  27. João Paulo Barraca and Rui L. Aguiar. A Framework for User-centric Autonomic Management. In Proceedings of the 11th Conferência sobre Redes de Computadores. November 2011. [ pdf ] [ BibTex ] [ +Info]

    Abstract

    This paper presents a novel autonomic management framework for user-centric networks. The framework assumes users are directly involved, or have direct interest, on their communication system, and as such, place user-related constrains on the behavior of the system. Groups of interest, formed either implicitly or explicitly, by users are considered inside the community concept, which the framework supports. For the realization of this concept, we require a new knowledge and logic layer, which we describe. This framework has been instantiated and tested in a small environment. The results showed the added flexibility of our framework, and its ability to integrated diverse user requirements.

    URL: http://hdl.handle.net/10773/7962

  28. Filipe Dias, João Paulo Barraca, Diogo Gomes, and Rui L. Aguiar. Characterization of Unplanned Metropolitan Wireless Networks. In Proceedings of the 10th Conferência sobre Redes de Computadores. Braga, Portugal, 2010. [ pdf ] [ BibTex ] [ +Info]

    Abstract

    Mobile Internet penetration has grown steadily over the last few years. Although most of today's users have access through their 3G Mobile Operators, there are still regions that are under-covered for various reasons. Wireless Mesh Networks (WMN) can play an important role by providing the means to fully cover those underserved regions. Due to their intrinsic nature, WMN require a critical mass of nodes belonging to the mesh in order to be effective. In this paper we present a study conducted in Aveiro, Portugal which intends to draw some conclusions on the feasibility of deploying a WMN in small to medium cities based on the cooperation of its inhabitants and on off-the-shelf wireless equipment.

  29. João Paulo Barraca, Diogo Gomes, and Rui L. Aguiar. AMazING - Advanced Mobile wIreless Network playGround. In Thomas Magedanz, Anastasius Gavras, NguyenHuu Thanh, and JeffryS. Chase, editors, Testbeds and Research Infrastructures. Development of Networks and Communities, volume 46 of Lecture Notes of the Institute for Computer Sciences, Social Informatics and Telecommunications Engineering, 219–230. Springer Berlin Heidelberg, May 2010. [ pdf ] [ BibTex ] [ +Info]

    Abstract

    We describe a wireless testbed composed by 24 wireless nodes that can be used to perform a broad range of studies in the area of next generation networks. This paper addresses the difficulties and constrains faced by the authors throughout the deployment process of such testbed. Flexibility and controllability were key concerns driving the testbed design. The testbed can be remotely managed through a series of remotely accessible web services performing low-level management. Validation results are presented, showing the interference levels of the testbed as well as its maximum throughput capabilities.

    URL: http://link.springer.com/chapter/10.1007\%2F978-3-642-17851-118

  30. Luís Couto, João Paulo Barraca, Susana Sargento, and Rui L. Aguiar. FastM in WMN: A Fast Mobility Support Extension for Wireless Mesh Networks. In Proceedings of the 2009 Second International Conference on Advances in Mesh Networks, 90–96. IEEE Computer Society, June 2009. [ pdf ] [ BibTex ] [ +Info]

    Abstract

    In this paper we present a new extension to proactive routing protocols using a fast mobility extension, FastM, with the purpose of increasing handover performance in wireless mesh networks. With this new extension a new concept is created to integrate information between neighbor wireless mesh routers, managing locations of clients associated to wireless mesh routers in a certain neighborhood, and avoiding packet loss during handover. The proposed mobility protocol is able to optimize the handover process without imposing any modifications to the current IEE 802.11 MAC protocol and use unmodified clients. Results show the improved efficiency of the proposed scheme: metrics such as disconnection time, throughput, packet loss and control overhead are largely improved when compared to previous approaches.

    URL: http://dx.doi.org/10.1109/MESH.2009.23

  31. L Couto, João Paulo Barraca, Susana Sargento, and Rui L. Aguiar. Fast Mobility in Proactive Routing Protocols. In Mobile & Wireless Communications Summit, volume 8. June 2008. [ pdf ] [ BibTex ] [ +Info]

    Abstract

    This paper presents an innovative extension to routing protocols using a back-tracing technique to improve performance of handovers in wireless mesh networks. The main purpose of this extension is to minimize disconnection time and packets losses when mobility occurs. The proposed scheme requires some minor changes to the original proactive ad-hoc routing protocol, but does not impose any modification to the current IEE 802.11 MAC protocol. Some additional changes are also required to the handover signalling, in order to better optimize the process. The back-tracing mechanism is also able to reach route convergence to a minimum route length maintaining the throughput of data packets. The results of the proposed extension show that it is able to maintain the network throughput in wireless mesh networks during mobility, minimizing the packet losses.

  32. João Paulo. Barraca and Rui L. Aguiar. Ontology-driven Framework for Community Networking Management. In Proceedings of the International Conference on Telecommunications, 2008 (ICT 2008), 1–7. June 2008. [ pdf ] [ BibTex ] [ +Info]

    Abstract

    Wireless technologies present many benefits when used to deploy metropolitan networks. Resilience, cost, adaptability and self-organization are some of the benefits provided by Wireless Networks. Especially when mesh technologies are used, wireless networks are adequate for the deployment of (user-centric) community networks. The increased participation of users and the social relations existing among them makes desirable the merging of the mesh and social aspect of these networks. If proper interfaces are deployed, users are able to map existing (or to be developed) social structures such as communities into the mesh network. This paper focuses on the problem of creating a community driven mesh network, and in the representation and maintenance of user relations, trust and functional parameters. We present a novel ontology designed for the management of such environments.

    URL: http://ieeexplore.ieee.org/xpl/articleDetails.jsp?arnumber=4652671

  33. João Paulo Barraca, Pedro Fernandes, Susana Sargento, and Rui Rocha. An Architecture For Community Mesh Networking. In Proceedings of the IEEE 19th International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC 2008). September 2008. [ pdf ] [ BibTex ] [ +Info]

    Abstract

    The advances on wireless mesh networks are shifting the communications paradigm, where users can benefit from their cooperation to exchange information and make use of the spectrum space, forming wireless neighbourhood communities where resources are shared and services are distributed. This paper presents a modular cross-layer community management architecture, which considers that communities are formed and managed at different layers, from physical to application. It focus in more depth on one of its modules, implementing a community discovery mechanism designed to work in wireless mesh networks, and able to perform community advertisement and discovery with low overhead and delay, as compared to current approaches.

    URL: http://ieeexplore.ieee.org/xpl/articleDetails.jsp?arnumber=4699908

  34. João Paulo Barraca and Rui L. Aguiar. Managing Community-aware Wireless Mesh Networks. In Proceedings of the IEEE Symposium on Computers and Communications (ISCC), 278–285. July 2008. [ pdf ] [ BibTex ] [ +Info]

    Abstract

    Wireless Mesh Networks, due to their typical architecture and deployment, are able to respond to user expectations as no other technology allows. Its typical multi-level approach facilitates local interactions by nearby wireless nodes from multiple users. Also, adaptation to user expectations on a dynamic manner is able to of further enhancing the capacity of these networks, while increasing its ubiquity. Nevertheless, these networks have no management model. In the paper we present the foundations for a management model for community aware networking. Design challenges for community management are identified and a management framework supporting the relevant concepts, linking social aspects and technology, is described.

    URL: http://ieeexplore.ieee.org/xpl/articleDetails.jsp?arnumber=4625741

  35. João Paulo Barraca, Susana Sargento, and Rui L. Aguiar. Role Based Cross-Layer Communities in WMN. In Proceedings of the International Conference on Wireless Information Networks and Systems (WINSYS), WINSYS, 85–92. INSTICC Press, July 2007. [ pdf ] [ BibTex ] [ +Info]

    Abstract

    The community notion can be exploited as a rational concept leading users to cooperate in sharing resourceson Wireless Mesh Networks. We propose a novel concept for self-organizing networks, where multipleentities (network elements or users) collaborate to achieve common goals, and in particular, to establish thebasic connectivity and service delivery infrastructures. The resulting architecture is based on wireless meshcommunications, with different entities taking different roles in the communities in a cross-layer approach.These communities can collaborate, leading to increasingly complex and geographically extended scenarios.

    URL: http://www.informatik.uni-trier.de/\textasciitilde ley/db/conf/winsys/winsys2007.html

  36. Miguel Almeida, Rafael Sarrô, João Paulo Barraca, Rui L. Aguiar, and Susana Sargento. On The Limits of Ad-hoc Networks - Experimental Evaluation. In 6th Conference on Telecommunications. 2007. [ pdf ] [ BibTex ] [ +Info]

    Abstract

    This paper presents an experimental evaluation of a multi-service Ad-hoc network architecture, interconnected with a fixed network. This network supports the efficient delivery of services, unicast and multicast, legacy and multimedia, to users connected in the ad-hoc network. It contains the support for routing with delivery of multicast services, mobility, QoS mechanisms to support service differentiation and resource control responsive to node mobility as well as security, charging and rewarding mechanisms to ensure the correct behaviour of the users in the ad-hoc network. This paper experimentally evaluates the performance of the proposed mechanisms, and the influence and performance penalty introduced in the network, with the incremental inclusion of new functionalities. Results, although biased by the software implementations, may question the usage of ad-hoc networks for more than a minimal number of hops.

  37. João Paulo Barraca, Miguel Almeida, Rafael Sarrô, Susana Sargento, and Rui L. Aguiar. Experimental evaluation of an integrated ad-hoc network. In IST Mobile Wireless Summity. June 2006. [ pdf ] [ BibTex ] [ +Info]

    Abstract

    This paper presents an experimental evaluation of an Ad-hoc network architecture integrated with the infrastructure network, developed in the framework of the IST Daidalos project. This architecture supports the efficient delivery of services, unicast and multicast, legacy and multimedia, to users connected to the ad-hoc network. It contains functionalities of routing and mobility to enable mobility of users inside and between ad-hoc networks, distributed QoS mechanisms to support service differentiation and resources control responsive to nodes mobility, and security, charging and rewarding mechanisms to ensure the correct behaviour of the users in the ad-hoc network. This paper experimentally evaluates the performance of the proposed mechanisms, and the influence and performance penalty introduced in the architecture, with the incremental inclusion of the proposed mechanisms.

  38. Susana Sargento, Tânia Calçada, João Paulo Barraca, Sérgio Crisóstomo, João Girão, Marek Natkaniec, Norbert Vicari, Francisco Cuesta, and Manuel Ricardo. Mobile Ad-Hoc Networks Integration in the Daidalos Architecture. In IST Mobile and Wireless Communications Summit. Dresden, Germany, June 2005. IST Mobile Summit 2005. [ pdf ] [ BibTex ] [ +Info]

    Abstract

    This paper describes the Ad-hoc network integration architecture being developed inside the IST project Daidalos. This architecture contains the required functionalities to support efficient delivery of services, unicast and multicast, legacy and multimedia, to users connected to the ad-hoc network. For this purpose, several functionalities need to be in place. First, efficient routing and mobility mechanisms are proposed to decrease the overhead in the ad-hoc network. Second, distributed QoS mechanisms need to be developed to support service differentiation and resources control responsive to nodes mobility. Finally, security, charging and rewarding mechanisms are proposed to guarantee that only authorized users access the requested services, to increase the operators interest, and to ensure the correct behaviour of the users in the ad-hoc network.

    URL: http://www.mobilesummit2005.org/

  39. João Girão, Bernd Lamparter, Dirk Westhoff, Rui Aguiar, and João Paulo Barraca. Linking ad hoc charging schemes to aaac architectures. In Claude Castelluccia, Hannes Hartenstein, Christof Paar, and Dirk Westhoff, editors, Proceedings of the First European conference on Security in Ad-hoc and Sensor Networks, volume 3313 of ESAS'04, 66–81. January 2005. [ pdf ] [ BibTex ] [ +Info]

    Abstract

    The current state of todays networks allows us to take one step further in merging the research communitys work with every days life. Wireless ad hoc networks are already well developed for specific scenarios. This work shows how to build the link between the wired network and a wireless ad hoc infrastructure, in particular routing and AAAC aspects. Such integration might lead, for example, to a better spacial and resource distributed hotspot solution. We provide the basis for inter-operation of AAAC protocols known for the fixed network, with the accounting protocol that performs the accounting and charging functions in the ad hoc network. This paper further describes the implementation of the Secured Charging Protocol as an instantiation of a charging protocol for ad hoc networks and the features which were added to improve the interface to an external accounting system. It covers the interaction with the MANET routing protocol and how to deal with routes to or from outside the ad hoc cloud.

    URL: http://dx.doi.org/10.1007/978-3-540-30496-87

  40. João Paulo Barraca, Susana Sargento, and Rui L. Aguiar. The Polynomial-Assisted Ad Hoc Charging Protocol. In Proceedings of the 10th IEEE Symposium on Computers and Communications, ISCC '05, 945–952. IEEE Computer Society, 2005. [ pdf ] [ BibTex ] [ +Info]

    Abstract

    The area of trustworthy charging in self-organized environments has been developed quite recently. This paper introduces a new secure charging-protocol, the polynomial-assisted charging protocol, for these environments. The protocol relies on polynomial composition for speeding the identification process in small groups. This protocol is able to provide strict guarantees of cooperative behavior in traffic forwarding, with minimal network overhead. Protocol performance is evaluated in multiple ad-hoc environments and results are compared with previously proposed work. The performance results show the merits of this protocol in multiple types of environments.

    URL: http://ieeexplore.ieee.org/xpl/articleDetails.jsp?arnumber=1493837

  41. João Paulo Barraca, Susana Sargento, and Rui L. Aguiar. Evaluation of MANET Charging Protocols in Hotspot Scenarios. In Conferência sobre Redes de Comunicações. 2005. [ pdf ] [ BibTex ] [ +Info]

    Abstract

    This document compares several proposals for charging and rewarding mechanisms in ad-hoc networks, in terms of its real-time charging efficiency and impact on the overall network throughput. We notice that the introduction of charging and rewarding mechanisms in the ad-hoc network may have impact on the network performance, and then these proposals must be carefully chosen.

  42. João Paulo Barraca, Susana Sargento, and Rui L. Aguiar. A Lightweight and Secure Session-Aware Ad-Hoc Charging Protocol. In International Conference on Telecommunications - ICT. May 2005. [ pdf ] [ BibTex ] [ +Info]

    Abstract

    Ad-hoc networks can be used to increase the radio range of hotspot scenarios and the number of prospective clients. However, the constraints created by the nature of wireless links and low power devices pose many challenges to this integration. Charging and efficient forwarding are two key functionalities in an ad-hoc network in order to allow its integration in the existing infrastructure networks. This paper proposes a lightweight and secure Session-Aware charging protocol (SACP) for these environments. This protocol is able to provide guarantees of cooperative behavior in traffic forwarding, with minimal network overhead. The performance results, evaluated in multiple environments, show the protocol merits in terms of throughput and network overhead.

  43. J. Girão, João Paulo Barraca, B. Lamparter, D. Westhoff, and R. Aguiar. QoS-Differentiated Secure Charging in Ad-Hoc Environments. In JoséNeuman Souza, Petre Dini, and Pascal Lorenz, editors, Telecommunications and Networking - ICT 2004, volume 3124 of Lecture Notes in Computer Science, 1093–1100. Springer Berlin Heidelberg, 2004. doi:10.1007/978-3-540-27824-5_142. [ pdf ] [ BibTex ] [ +Info]

    Abstract

    In order to keep up with new networking needs, it is necessary to adopt mechanisms for charging network usage in a universal way. The Secure Charging Protocol (SCP) aims at answering this complex authentication, authorization, accounting and charging (AAAC) problem. SCP fits business models especially adequate for ad-hoc networks. This document discusses SCP as a possible solution to the AAAC problems in MANETs and presents the improvements made to this protocol in terms of Quality of Service (QoS). An implementation of this protocol on PDAs and the results achieved are discussed.

@mastersthesis

  1. João Paulo Barraca. Mechanisms for Secure Charging in Self-Organised Networks. Master's thesis, University of Aveiro, December 2006. [ pdf ] [ BibTex ] [ +Info]

    Abstract

    Self-organised and ad-hoc networks are an area with an existing large research community. These networks are much useful in scenarios requiring a rapidly deployed, low cost and highly adaptable network. Recently, infrastructure networks, which are managed in a much centralised form, are starting to introduce concepts of self-organised networks in its architecture. In opposition to centralised systems, self-organisation creates the necessity for all nodes to behave according to the best interest of the network. The fact that in many ad-hoc networks nodes have scarce resources poses some threats to this requirement. As resources decreases, such as battery or wireless bandwidth, nodes can start acting selfishly. This behaviour is known to bring damage to self-organised networks and threatens the entire network. Several proposals were made in order to promote the correct usage of the network. Some proposals are based on local information and direct credit exchange while others envision the existence of a central bank. The later solutions are further elaborated in this thesis, as they make possible integration of ad-hoc network with operator driven infrastructures. This work presents the current state-of-the-art on the area providing a detailed insight on the methods adopted by each solution presented. Two novel solutions are proposed providing charging support for integrated ad-hoc networks. Both solutions provide means of integration with standard management methods found in operator networks. Also, node's motivation is increased through the reward of nodes forwarding data packets. The entire process is cryptographically secure, making use of standard methods such as Elliptic Curve DSA and strong digest functions. The solutions proposed are described and analysed analytically, comparing the results with other state-of-the-art proposals. Extensive simulation work is also presented which furthers evaluates the solutions in complex scenarios. Results are obtained from these scenarios and several metrics are evaluated taking in consideration mobility, network load, routing protocol and transport protocol. The architecture and results obtained with a real implementation are finally presented and analysed.

    URL: http://hdl.handle.net/10773/1872

@phdthesis

  1. João Paulo Barraca. Establishment of Stackable Community Networks. PhD thesis, University of Aveiro, Dec 2012. [ pdf ] [ BibTex ] [ +Info]

    Abstract

    One of the research areas with increasing interest in the field of telecommunications, are the ones related to future telecommunication systems, both 4th generation and beyond. In parallel, during the last years, several concepts have been developed related to clustering of users according to their interested, in the form of community networks. Solutions proposed for these concepts tackle the challenges horizontally, for each layer of the communication stack, ranging from community based communication networks (e.g. Seattle Wireless, or Personal Telco), to interest networks based on peer-to-peer protocols. However, these networks are presented either as free joining, or overlay networks. In practice, the notion of a self-organized, service and community oriented network, with these principles embedded in its design principles, is yet to be developed. This work presents an novel instantiation of a solution in the area of community networks, with a underlying architecture which is fully service oriented, and envisions the support for multiple community networks in the same device. Considerations regarding security, trust and service availability for this type of environments are also taken. Due to the importance of resource management and access control, in the context of community driven communication networks, a special focus was given to the support of scalable and decentralized management and access control methods. For this purpose, it is presented a policy language which supports the creation and management of virtual communities. The language is not only used for mapping the social structure of the community members, but also to, following a distributed approach, manage devices, resources and services owned by each community member.