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- An Efficient approach to Multisuperframe tuning for DSME networksPublication . Kurunathan, Harrison; Severino, Ricardo; Koubâa, AnisDeterministic Synchronous Multichannel Extension (DSME) is a prominent MAC behavior irst introduced in IEEE 802.15.4e that supports deterministic guarantees using its multisuperframe structure. DSME also facilitates techniques like multi-channel and CAP reduction that help to increase the number of available guaranteed timeslots in a network. However, no tuning of these functionalities in dynamic scenarios is supported in the standard. In this paper, we present an efective multisuperframe tuning technique that also helps to utilize CAP reduction in an efective manner improving lexibility and scalability, while guaranteeing bounded delay.
- A Drone Secure Handover Architecture validated in a Software in the Loop EnvironmentPublication . Vasconcelos Filho, Ênio; Gomes, Filipe; Monteiro, Stéphane; Penna, Sergio; Koubaa, Anis; Tovar, Eduardo; Severino, RicardoThe flight and control capabilities of uncrewed aerial vehicles (UAVs) have increased significantly with recent research for civilian and commercial applications. As a result, these devices are becoming capable of flying ever greater distances, accomplishing flights beyond line of sight (BVLOS). However, given the need for safety guarantees, these flights are increasingly subject to regulations. Handover operations between controllers and the security of the exchanged data are a challenge for implementing these devices in various applications. This paper presents a secure handover architecture between control stations, using a Software in the Loop (SIL) model to validate the adopted strategies and mitigate the time between simulation and real systems implementations. This architecture is developed in two separate modules that perform the security and handover processes. Finally, we validate the proposed architecture with several drone flights on a virtual testbed.
- Cooperative Vehicular Platooning: A Multi- Dimensional Survey Towards Enhanced Safety, Security and ValidationPublication . Vasconcelos Filho, Ênio; Santos, Pedro Miguel; Koubaa, Anis; Tovar, Eduardo; Severino, RicardoCooperative Vehicular Platooning (Co-VP) is a paradigmatic example of a Cooperative Cyber-Physical System (Co-CPS), which holds the potential to vastly improve road safety by partially removing humans from the driving task. However, the challenges are substantial, as the domain involves several topics, such as control theory, communications, vehicle dynamics, security, and traffic engineering, that must be coupled to describe, develop and validate these systems of systems accurately. This work presents a comprehensive survey of significant and recent advances in Co-VP relevant fields. We start by overviewing the work on control strategies and underlying communication infrastructures, focusing on their interplay. We also address a fundamental concern by presenting a cyber-security overview regarding these systems. Furthermore, we present and compare the primary initiatives to test and validate those systems, including simulation tools, hardware-in-the-loop setups, and vehicular testbeds. Finally, we highlight a few open challenges in the Co-VP domain. This work aims to provide a fundamental overview of highly relevant works on Co-VP topics, particularly by exposing their inter-dependencies, facilitating a guide that will support further developments in this challenging field.
- A microscope for the data centerPublication . Pereira, Nuno; Tennina, Stefano; Loureiro, João; Severino, Ricardo; Saraiva, Bruno; Santos, Manuel; Pacheco, Filipe; Tovar, EduardoNowadays, data centers are large energy consumers and the trend for next years is expected to increase further, considering the growth in the order of cloud services. A large portion of this power consumption is due to the control of physical parameters of the data center (such as temperature and humidity). However, these physical parameters are tightly coupled with computations, and even more so in upcoming data centers, where the location of workloads can vary substantially due, for example, to workloads being moved in the cloud infrastructure hosted in the data center. Therefore, managing the physical and compute infrastructure of a large data center is an embodiment of a Cyber-Physical System (CPS). In this paper, we describe a data collection and distribution architecture that enables gathering physical parameters of a large data center at a very high temporal and spatial resolution of the sensor measurements. We think this is an important characteristic to enable more accurate heat-flow models of the data center and with them, find opportunities to optimize energy consumptions. Having a high-resolution picture of the data center conditions, also enables minimizing local hot-spots, perform more accurate predictive maintenance (failures in all infrastructure equipments can be more promptly detected) and more accurate billing. We detail this architecture and define the structure of the underlying messaging system that is used to collect and distribute the data. Finally, we show the results of a preliminary study of a typical data center radio environment.
- Poster/Demo Session Proceedings of the 12th European Conference on Wireless Sensor Networks (EWSN'15) CPublication . Severino, Ricardo; Handzisky, Vlado; Jurdak, RajaThe poster and Demo session is an integral part of the EWSN conference.
- Towards a Realistic Simulation Framework for Vehicular Platooning ApplicationsPublication . Vieira, Bruno; Severino, Ricardo; Koubaa, Anis; Tovar, EduardoCooperative vehicle platooning applications increasingly demand realistic simulation tools to ease their validation, and to bridge the gap between development and real-word deployment. However, their complexity and cost, often hinders its validation in the real-world. In this paper we propose a realistic simulation framework for vehicular platoons that integrates Gazebo with OMNeT++ over Robot Operating System (ROS) to support the simulation of realistic scenarios of autonomous vehicular platoons and their cooperative control.
- A traffic differentiation add-on to the IEEE 802.15.4 protocol: implementation and experimental validation over a real-time operating systemPublication . Severino, Ricardo; Batsa, Manish; Alves, Mário; Koubaa, AnisThe IEEE 802.15.4 is the most widespread used protocol for Wireless Sensor Networks (WSNs) and it is being used as a baseline for several higher layer protocols such as ZigBee, 6LoWPAN or WirelessHART. Its MAC (Medium Access Control) supports both contention-free (CFP, based on the reservation of guaranteed time-slots GTS) and contention based (CAP, ruled by CSMA/CA) access, when operating in beacon-enabled mode. Thus, it enables the differentiation between real-time and best-effort traffic. However, some WSN applications and higher layer protocols may strongly benefit from the possibility of supporting more traffic classes. This happens, for instance, for dense WSNs used in time-sensitive industrial applications. In this context, we propose to differentiate traffic classes within the CAP, enabling lower transmission delays and higher success probability to timecritical messages, such as for event detection, GTS reservation and network management. Building upon a previously proposed methodology (TRADIF), in this paper we outline its implementation and experimental validation over a real-time operating system. Importantly, TRADIF is fully backward compatible with the IEEE 802.15.4 standard, enabling to create different traffic classes just by tuning some MAC parameters.
- Tightening Up Security In Low Power Deterministic NetworksPublication . Tiberti, Walter; Vieira, Bruno; Kurunathan, John Harrison; Severino, Ricardo; Tovar, EduardoThe unprecedented pervasiveness of IoT systems is pushing this technology into increasingly stringent domains. Such application scenarios become even more challenging due to the demand for encompassing the interplay between safety and security. The IEEE 802.15.4 DSME MAC behavior aims at addressing such systems by providing additional deterministic, synchronous multi-channel access support. However, despite the several improvements over the previous versions of the protocol, the standard lacks a complete solution to secure communications. In this front, we propose the integration of TAKS, an hybrid cryptography scheme, over a standard DSME network. In this paper, we describe the system architecture for integrating TAKS into DSME with minimum impact to the standard, and we venture into analysing the overhead of having such security solution over application delay and throughput. After a performance analysis, we learn that it is possible to achieve a minor impact of 1% to 14% on top of the expected network delay, depending on the platform used, while still guaranteeing strong security support over the DSME network.
- Open-ZB: an open-source implementation of the IEEE 802.15.4/ZigBee protocol stack on TinyOSPublication . Cunha, André; Koubâa, Anis; Severino, Ricardo; Alves, MárioThe IEEE 802.15.4/ZigBee protocols are gaining increasing interests in both research and industrial communities as candidate technologies for Wireless Sensor Network (WSN) applications. In this paper, we present an open-source implementation of the IEEE 802.15.4/Zigbee protocol stack under the TinyOS operating system for the MICAz motes. This work has been driven by the need for an open-source implementation of the IEEE 802.15.4/ZigBee protocols, filling a gap between some newly released complex C implementations and black-box implementations from different manufacturers. In addition, we share our experience on the challenging problem that we have faced during the implementation of the protocol stack on the MICAz motes. We strongly believe that this open-source implementation will potentiate research works on the IEEE 802.15.4/Zigbee protocols allowing their demonstration and validation through experimentation.
- Zigbee over tinyos: Implementation and experimental challengesPublication . Cunha, André; Severino, Ricardo; Pereira, Nuno; Koubâa, Anis; Alves, MárioThe IEEE 802.15.4/Zigbee protocols are a promising technology for Wireless Sensor Networks (WSNs). This paper shares our experience on the implementation and use of these protocols and related technologies in WSNs. We present problems and challenges we have been facing in implementing an IEEE 802.15.4/ZigBee stack for TinyOS in a two-folded perspective: IEEE 802.15.4/ZigBee protocol standards limitations (ambiguities and open issues) and technological limitations (hardware and software). Concerning the former, we address challenges for building scalable and synchronized multi-cluster ZigBee networks, providing a trade-off between timeliness and energy-efficiency. On the latter issue, we highlight implementation problems in terms of hardware, timer handling and operating system limitations. We also report on our experience from experimental test-beds, namely on physical layer aspects such as coexistence problems between IEEE 802.15.4 and 802.11 radio channels.