Feb 25 - Aida Ehyaei, ISEP, Portugal - Scalable Data Acquisition for Densely Instrumented Cyber-Physical Systems¶

Talk abstract: Consider the problem of designing an algorithm for acquiring sensor readings. Consider specifically the problem of obtaining an approximate representation of sensor readings where (i) sensor readings originate from different sensor nodes, (ii) the number of sensor nodes is very large, (iii) all sensor nodes are deployed in a small area (dense network) and (iv) all sensor nodes communicate over a communication medium where at most one node can transmit at a time (a single broadcast domain). We present an efficient algorithm for this problem, and our novel algorithm has two desired properties: (i) it obtains an interpolation based on all sensor readings and (ii) it is scalable, that is, its time-complexity is independent of the number of sensor nodes. Achieving these two properties is possible thanks to the close interlinking of the information processing algorithm, the communication system and a model of the physical world.

Speaker Bio.: Aida Ehyaei received her MSc. and BSc. degree in Electrical engineering from Isfahan University of technology, Iran. She is a PhD student in FEUP and does her research in CISTER Research Unit from September 2009. Currently, her research is in the field of Cyber Physical Systems.

Talk slides: pdf

March 4 - Claro Noda, ISEP, Portugal - Channel Quality Metric for Interference-aware WSN¶

Talk abstract:WSN operate in ISM bands and share the spectrum with other wireless technologies, thus interference is a relevant problem. In order to minimise its effect nodes can dynamically adapt radio resources to accommodate network traffic, provided information about spectrum usage is available. We present a new channel quality metric that is based on availability of the channel over time. We do experiments to investigate its parameter space and also show our metric has strong correlation with Packet Reception Rate. This suggest that quantifying interference in the channel can help in adapting radio resources to boost reliability and bound latency in packet delivery. We then entertain some resource adaptation techniques where the metric can help optimising them according to the channel condition.

Speaker Bio.:Claro Noda graduated in Physics from University of Havana, Cuba in 1996. He worked in Scientific Instrumentation at the Superconductivity Laboratory, IMRE (1996-2001) where he completed his Master in Physical Sciences in 2000 and later continued research activities at the "Henri Poincaré" Complex Systems Group. He has also taught at the General Physics Department in the Faculty of Physics in Havana (2005-2008). Currently he's a MAP-Tele PhD student at University of Minho and a researcher at CISTER/ISEP, Portugal.

March 11 - Gurulingesh Raravi, ISEP, Portugal - Assigning Real-Time Tasks on a Two-type Heterogeneous Multiprocessor Platform¶

Talk abstract:Consider the problem of scheduling a set of implicit-deadline sporadic tasks on a heterogeneous multiprocessor platform to meet all deadlines. Tasks cannot migrate and each processor is either of type-1 or type-2 (with each task having different execution speed on each processor type). We present a new algorithm, FF-3C, for this problem. FF-3C offers low time-complexity and provably good performance. Specifically, (i) its time-complexity is O(n * max(m; log n)), where n is the number of tasks and m is the number of processors and (ii) it offers the guarantee that if a task set can be scheduled by an optimal task assignment scheme to meet deadlines then FF-3C meets deadlines as well if given processors twice as fast. We also present several extensions to FF-3C; these offer the same time-complexity and performance guarantee as that of FF-3C but in addition, they offer improved average-case performance. Via experiments with randomly generated task sets, we compare the performance of our new algorithms and two established state-of-art algorithms (and variations of the latter). We evaluate algorithms based on (i) running time and (ii) the necessary multiplication factor, i.e., the amount of extra speed of processors the algorithm needs, for a given task set, so as to succeed, compared to an optimal task assignment scheme. Overall our new algorithms compare favorably to the state-of-art. One in particular (FF-4CCOMB), in our experimental evaluations, runs 12000 to 160000 times faster and has significantly smaller necessary multiplication factor than state-of-art algorithms.

Speaker Bio.:Gurulingesh Raravi finished his Masters Degree at IIT Bombay in 2005. He has three years of working experience. Currently, he is pursuing PhD in the area of Real-Time Scheduling on Heterogeneous Multiprocessor Platform.

Talk slides:pdf

Paper:Assigning Real-Time Tasks on Heterogeneous Multiprocessors with Two Unrelated Types of Processors(pdf)

March 18 - Vikram Gupta, ISEP, Portugal - Nano-CF: A Coordination Framework for Macro-programming in Wireless Sensor Networks¶

Talk abstract: Wireless Sensor Networks (WSN) are being used for a number of applications involving infrastructure monitoring, building energy monitoring and industrial sensing. The difficulty of programming individual sensor nodes and the associated overhead have encouraged researchers to design macro-programming systems which can help program the network as a whole or as a combination of subnets. In this paper, we propose a maro-programming framework called Nano-CF, which, in addition to supporting in-network programming, allows multiple applications written by different programmers to be executed simultaneously on a sensor networking infrastructure. This framework enables the use of a common sensing infrastructure for a number of applications without the users being concerned about the applications already deployed on the network. The framework also supports timing constraints and resource reservations using the Nano-RK operating system. Nano-CF is efficient at improving WSN performance by (a) combining multiple user programs, (b) aggregating packets for data delivery, and (c) satisfying timing and energy specifications using Rate-Harmonized Scheduling. Using representative applications, we demonstrate that Nano-CF achieves 90% reduction in Source Lines-of-Code (SLoC) and 50% energy savings from aggregated data delivery

Speaker Bio.:Vikram Gupta is a PhD candidate in Electrical and Computer Engineering in the Carnegie Mellon University (CMU) - Portugal joint program beginning August 2008 and is supervised by Prof. Raj Rajkumar (ECE-CMU) and Prof. Eduardo Tovar (ISEP-IPP). His current research includes developing clock synchronization methods for Wireless Sensor Networks. Before joining PhD program, he was working as a research associate at Indian Institute of Technology (I.I.T.) Delhi, India, where he focussed on Performance Assessment and Interoperability of WiMAX (802.16) on a Campus based Test Bed. He received his degree of Bachelor of Technology from National Institute of Technology (V.N.I.T.) Nagpur India in May 2007.

Talk slides: pdf

March 25 - Paulo Balrarejo Sousa, ISEP, Portugal - How to implement a new scheduling policy for Linux kernel¶

Talk abstract: Modifying some part of the Linux kernel source code, is, usually, a great dilemma. On one hand, it is a challenging task to make modifications to the source code of the Linux kernel, but, on the other hand, it is a scaring task. The Linux kernel source code is composed by thousands of code lines divided by hundred of files, and, consequently, it is a hard task performing changes on the Linux kernel. In this paper we present a detailed description on how to implement a new scheduling policy for Linux 2.6.34 kernel version. The scheduling algorithm considered for implementation, is the well known real-time scheduling algorithm EDF.

Speaker Bio.: Paulo Baltarejo Sousa is a researcher on scheduling algorithms for Multicore processors at CISTER Research Group and also a Lecturer at the Polytechnic Institute of Porto.

April 8 - Ricardo Severino, ISEP, Portugal - Enabling Accurate and Scalable Structural Health Monitoring with COTS-based Wireless Sensor Networks¶

Talk abstract: Structural health monitoring (SHM) has long been identified as a prominent application of Wireless Sensor Networks (WSNs), as wired-based solutions present inherent limitations such as installation/maintenance cost, scalability and visual impact. Nevertheless, there is still a lack of ready-to-use off-the-shelf WSN technologies able to meet some of the most demanding requirements imposed by SHM applications, such as low-power and low-cost yet extremely sensitive and accurate accelerometers and signal acquisition hardware, stringent time synchronization and system scalability. We will present a WSN system for SHM that merges the benefits of standard and off-the-shelf (COTS) technologies with a minimum set of custom-designed hardware. Our prototype system proved to be accurate and effective for low/high amplitude vibrations and in the time/frequency domains, when compared to a reference wired system. Importantly, we show how to scale up the WSN architecture to monitor larger structures, still guaranteeing tight time synchronization between all sensor measurements.

Speaker Bio: Ricardo Severino was born in 1982 and has a Degree (2006), and a MSc (2008) in Electrical and Computer Engineering at the Polytechnic Institute of Porto – School of Engineering (ISEP/IPP). Since 2006, he has been working in the area of Wireless Sensor Networks, namely on improving quality-of-service (QoS) in WSNs by using standard and commercial-off-the-shelf (COTS) technology, at the CISTER/IPP-HURRAY! Research Unit. In this line, he has been actively participating in the ART-WiSe (http://artwise.cister-isep.info) and Open-ZB (http://www.open-zb.net) research frameworks, as well as in international projects such as ArtistDesign (FP7 NoE on Embedded System Design), CONET (FP7 NoE on Cooperating Objects), and EMMON (FP7 JU on Embedded Monitoring). He is also a founding member and contributor of the 15.4 and ZigBee TinyOS Working Groups. Recently, his MSc Thesis work was awarded with the EWSN'09 Best MSc Thesis Award at the prestigious European Conference on Wireless Sensor Networks (EWSN'09). He has several publications in reputed conferences (e.g. MASS, RTCSA, ECRTS) and journals (e.g. IEEE TII) and has served as a reviewer for several conferences (e.g. IEEE ETFA, SUTC and VTC).

Talk slides: pdf

April 15 - Antonio Barros, ISEP, Portugal - Software transactional memory as a building block for parallel embedded real-time systems¶

Talk abstract: The recent trends of chip architectures with higher number of heterogeneous cores, and non-uniform memory/non-coherent caches, brings renewed attention to the use of Software Transactional Memory (STM) as a fundamental building block for developing parallel applications. Nevertheless, although STM promises to ease concurrent and parallel software development, it relies on the possibility of aborting conflicting transactions to maintain data consistency, which impacts on the responsiveness and timing guarantees required by embedded real-time systems. In these systems, contention delays must be (efficiently) limited so that the response times of tasks executing transactions are upper-bounded and task sets can be feasibly scheduled. In this paper we assess the use of STM in the development of embedded real-time software, defending that the amount of contention can be reduced if read-only transactions access recent consistent data snapshots, progressing in a wait-free manner. We also present an algorithm to manage conflicts between update transactions that prevents starvation. We show how the required number of versions of a shared object can be calculated for a set of tasks, and how to calculate the upper-bound of the response time of a task containing an update transaction.

Speaker Bio: António Barros got his degree (1997) and MSc (2009) on Electrical and Computer Engineering (Telecommunication and Computers) at FEUP. He is a lecturer at ISEP since 2001 and collaborates with CISTER since 2005. He is an enthusiast of reliable software and fantasizes about fault-tolerant distributed systems. He claims being genetically unable to program any kind of graphical user interface and computers should be hidden from common people.

Talk slides: pdf

April 29 - Dakshina Dasari, ISEP, Portugal - Analyzing Shared memory contention for COTS-based multicores¶

Talk abstract: This talk will focus on the problem of shared bus and shared memory contention in multicores, their impact on the WCET and discuss a method proposed to derive safe upper bounds for the WCET.

Speaker Bio: Dakshina Dasari has been a member of the CISTER research lab in the Adaptive Real Time Systems group since September 2009. Her current area of work involves studying the analysis of the impact of shared resources on the WCET of tasks running on multicores. Her other interests involve reading and music.

May 6 - Maryam Vahabi, ISEP, Portugal - Slotted WiDom: Schedulability Analysis and its Experimental Validation¶

Talk abstract: The main focus of this talk will be on Slotted-WiDom, a new version of WiDOM with lower overhead. It presents a schedulability analysis for slotted-WiDOM which is based on non-preemptive static-priority scheduling and schedulability analysis together with its experimental validation.

Speaker Bio: Maryam Vahabi received her degree in Electrical Engineering in 2003. She obtained her Master of Science in Communication Network Engineering in 2009. She has joined the CISTER research lab in July, 2009. Currently, she is working on the field of Wireless Sensor Network (WSN) and more specifically, WiDom protocol.

May 13 - Jose Marinho, ISEP, Portugal¶

May 20 - Artem Burmyakov, ISEP, Portugal¶

May 27 - Ricardo Garibay-Martinez, ISEP, Portugal¶

June 3 - Muhammad Ali Awan, ISEP, Portugal¶

June 17 - Borislav Nikolic, ISEP, Portugal¶

July 1 - Konstiantyn Berezovskyi, ISEP, Portugal¶

July 15 - Claudio Maia, ISEP, Portugal¶

July 22 - Hossein Fotouhi, ISEP, Portugal - Smart-HOP: A Reliable Handoff Procedure for Supporting Mobility in Wireless Sensor Networks¶

Talk abstract: Presents the smart-HOP approach which is a reliable multi-criteria decision making handoff mechanism for Wireless Sensor Network applications with mobility support. This technique relies on a fuzzy logic applied at two levels: the link quality estimation level and the access point selection level. The conceptual design of smart-HOP and the implementation challenges will also be discussed.

Speaker Bio: Hossein received his degree on Electrical Electronics Engineering in 2004 and worked afterwards about three years in Iran in different places such as University of Guilan and Telecommunication Center as a network engineer. He obtained his Master of Science in Communication Network Engineering in 2009. His MSc thesis was on "optimising energy consumption in MAC layer for Wireless Sensor Networks". Currently, he is doing his PhD research in CISTER Research Unit since July 2009. His research interests are wireless sensor networks, mobility management, handoff mechanism and fuzzy logic theory.

July 8 - Hazem Ali, ISEP, Portugal¶