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  • 151.
    Dowling, Jim
    et al.
    RISE, Swedish ICT, SICS, Computer Systems Laboratory.
    Haridi, Seif
    RISE, Swedish ICT, SICS, Computer Systems Laboratory.
    Decentralized Reinforcement Learning for the Online Optimization of Distributed Systems2008In: Reinforcement Learning: Theory and Applications, Vienna, Austria: I-Tech Education and Publishing (Advanced Robotic Systems Journal) , 2008, , p. 25p. 143-166Chapter in book (Refereed)
  • 152.
    Dowling, Jim
    et al.
    RISE - Research Institutes of Sweden, ICT, SICS.
    Sacha, Jan
    Haridi, Seif
    RISE, Swedish ICT, SICS, Computer Systems Laboratory.
    Improving ICE Service Selection in a P2P System using the Gradient Topology2007Conference paper (Refereed)
  • 153.
    Drejhammar, Frej
    RISE, Swedish ICT, SICS, Computer Systems Laboratory.
    Flow Java: Declarative Concurrency for Java2005Licentiate thesis, monograph (Other academic)
    Abstract [en]

    This thesis presents the design, implementation, and evaluation of Flow Java, a programming language for the implementation of concurrent programs. Flow Java adds powerful programming abstractions for automatic synchronization of concurrent programs to Java. The abstractions added are single assignment variables (logic variables) and futures (read-only views of logic variables). The added abstractions conservatively extend Java with respect to types, parameter passing, and concurrency. Futures support secure concurrent abstractions and are essential for seamless integration of single assignment variables into Java. These abstractions allow for simple and concise implementation of high-level concurrent programming abstractions. Flow Java is implemented as a moderate extension to the GNU gcj/libjava Java compiler and runtime environment. The extension is not specific to a particular implementation, it could easily be incorporated into other Java implementations. The thesis presents three implementation strategies for single assignment variables. One strategy uses forwarding and dereferencing while the two others are variants of Taylor's scheme. Taylor's scheme represents logic variables as a circular list. The thesis presents a new adaptation of Taylor's scheme to a concurrent language using operating system threads. The Flow Java system is evaluated using standard Java benchmarks. Evaluation shows that in most cases the overhead incurred by the extensions is between 10% and 50%. For some pathological cases the runtime increases by up to 150%. Concurrent programs making use of Flow Java's automatic synchronization, generally perform as good as corresponding Java programs. In some cases Flow Java programs outperform Java programs by as much as 33%.

  • 154.
    Drejhammar, Frej
    et al.
    RISE, Swedish ICT, SICS, Computer Systems Laboratory.
    Haridi, Seif
    RISE, Swedish ICT, SICS, Computer Systems Laboratory.
    Efficient simulation of view synchrony2012Report (Other academic)
    Abstract [en]

    This report presents an algorithm for efficiently simulating view synchrony, including failure-atomic total-order multicast in a discrete-time event simulator. In this report we show how a view synchrony implementation tailored to a simulated environment removes the need for third party middleware and detailed network simulation, thus reducing the complexity of a test environment. An additional advantage is that simulated view synchrony can generate all timing behaviours allowed by the model instead of just those exhibited by a particular view synchrony implementation.

  • 155.
    Drejhammar, Frej
    et al.
    RISE, Swedish ICT, SICS, Computer Systems Laboratory.
    Haridi, Seif
    RISE, Swedish ICT, SICS, Computer Systems Laboratory.
    Brand, Per
    RISE, Swedish ICT, SICS, Computer Systems Laboratory.
    Schulte, Christian
    Flow Java: declarative concurrency for Java.2003In: Proceedings of the Nineteenth International Conference on Logic Programming, 2003, 1Conference paper (Refereed)
    Abstract [en]

    Logic variables pioneered by (concurrent) logic and concurrent constraint programming are powerful mechanisms for automatically synchronizing concurrent computations. They support a declarative model of concurrency that avoids explicitly suspending and resuming computations. This paper presents Flow Java which conservatively extends Java with single assignment variables and futures as variants of logic variables. The extension is conservative with respect to object-orientation, types, parameter passing, and concurrency in Java. Futures support secure concurrent abstractions and are essential for seamless integration of single assignment variables into Java. We show how Flow Java supports the construction of simple and concise concurrent programming abstractions. We present how to moderately extend compilation and the runtime architecture of an existing Java implementation for Flow Java. Evaluation using standard Java benchmarks shows that in most cases the overhead is between 10% and 40%. For some pathological cases the runtime increases by up to 75%.

  • 156.
    Drejhammar, Frej
    et al.
    RISE, Swedish ICT, SICS, Computer Systems Laboratory.
    Rasmusson, Lars
    RISE, Swedish ICT, SICS, Computer Systems Laboratory.
    BEAMJIT: a just-in-time compiling runtime for Erlang2014Conference paper (Refereed)
    Abstract [en]

    BEAMJIT is a tracing just-in-time compiling runtime for the Erlang programming language. The core parts of BEAMJIT are synthesized from the C source code of BEAM, the reference Erlang abstract machine. The source code for BEAM's instructions is extracted automatically from BEAM's emulator loop. A tracing version of the abstract machine, as well as a code generator are synthesized. BEAMJIT uses the LLVM toolkit for optimization and native code emission. The automatic synthesis process greatly reduces the amount of manual work required to maintain a just-in-time compiler as it automatically tracks the BEAM system. The performance is evaluated with HiPE's, the Erlang ahead-of-time native compiler, benchmark suite. For most benchmarks BEAMJIT delivers a performance improvement compared to BEAM, although in some cases, with known causes, it fails to deliver a performance boost. BEAMJIT does not yet match the performance of HiPE mainly because it does not yet implement Erlang specific optimizations such as boxing/unboxing elimination and a deep understanding of BIFs. Despite this BEAMJIT, for some benchmarks, reduces the runtime with up to 40\%.

  • 157.
    Drejhammar, Frej
    et al.
    RISE, Swedish ICT, SICS, Computer Systems Laboratory.
    Schulte, Christian
    Implementation strategies for single assignment variables2004Conference paper (Refereed)
  • 158. Dron, Wilfried
    et al.
    Duquennoy, Simon
    RISE, Swedish ICT, SICS, Computer Systems Laboratory.
    Voigt, Thiemo
    RISE, Swedish ICT, SICS, Computer Systems Laboratory.
    Hachicha, Khalil
    Garda, Patrick
    An Emulation-based Method for Lifetime Estimation of Wireless Sensor Networks2014Conference paper (Refereed)
    Abstract [en]

    Lifetime estimation in Wireless Sensor Networks (WSN) is crucial to ensure that the network will last long enough (low maintenance cost) while not being over-dimensioned (low initial cost). Existing solutions have at least one of the two following limitations: (1) they are based on theoretical models or high-level protocol implementations, overlooking low-level (e.g., hardware, driver, etc.) constraints which we find have a significant impact on lifetime, and (2) they use an ideal battery model which over-estimates lifetime due to its constant voltage and its inability to model the non-linear properties of real batteries. We introduce a method for WSN lifetime estimation that operates on compiled firmware images and models the complex behavior of batteries. We use the MSPSim/Cooja node emulator and network simulator to run the application in a cycle-accurate manner and log all component states. We then feed the log into our lifetime estimation framework, which models the nodes and their batteries based on both technical and experimental specifications. In a case study of a Contiki RPL/6LoWPAN application, we identify and resolve several low-level implementation issues, thereby increasing the predicted network lifetime from 134 to 484 days. We compare our battery model to the ideal battery model and to the lifetime estimation based on the radio duty cycle, and find that there is an average over-estimation of 36% and 76% respectively.

  • 159.
    Dunkels, Adam
    et al.
    RISE, Swedish ICT, SICS.
    Alonso, Juan
    RISE - Research Institutes of Sweden, ICT, SICS.
    Voigt, Thiemo
    RISE, Swedish ICT, SICS, Computer Systems Laboratory.
    Making TCP/IP Viable for Wireless Sensor Networks2003Report (Other academic)
    Abstract [en]

    The TCP/IP protocol suite, which has proven itself highly successful in wired networks, is often claimed to be unsuited for wireless micro-sensor networks. In this work, we question this conventional wisdom and present a number of mechanisms that are intended to enable the use of TCP/IP for wireless sensor networks: spatial IP address assignment, shared context header compression, application overlay routing, and distributed TCP caching (DTC). Sensor networks based on TCP/IP have the advantage of being able to directly communicate with an infrastructure consisting either of a wired IP network or of IP-based wireless technology such as GPRS. We have implemented parts of our mechanisms both in a simulator environment and on actual sensor nodes, and preliminary results are promising.

  • 160.
    Dunkels, Adam
    et al.
    RISE, Swedish ICT, SICS.
    Alonso, Juan
    RISE - Research Institutes of Sweden, ICT, SICS.
    Voigt, Thiemo
    RISE, Swedish ICT, SICS, Computer Systems Laboratory.
    Ritter, Hartmut
    Distributed TCP Caching for Wireless Sensor Networks2004Report (Other academic)
    Abstract [en]

    Previous research on transport layer protocols for wireless sensor networks (WSNs) has focused on designing protocols specifically targeted for sensor networks. Most sensor networks applications, however, are only useful when connected to an external network. The deployment of TCP/IP in WSNs would enable direct connection between the WSN and external TCP/IP networks. However, TCP performs badly in wireless environments both in terms of throughput and energy efficiency. To overcome these problems in WSNs we have designed Distributed TCP Caching. This mechanism greatly enhances TCP performance by caching TCP segments on the nodes in the sensor network and locally retransmitting lost segments. Our simulations demonstrate that with these enhancements TCP performs well enough to be useful in wireless sensor networks.

  • 161.
    Dunkels, Adam
    et al.
    RISE, Swedish ICT, SICS.
    Eriksson, Joakim
    RISE, Swedish ICT, SICS, Computer Systems Laboratory.
    Finne, Niclas
    RISE, Swedish ICT, SICS, Computer Systems Laboratory.
    Tsiftes, Nicolas
    RISE, Swedish ICT, SICS, Computer Systems Laboratory.
    Powertrace: Network-level Power Profiling for Low-power Wireless Networks2011Report (Other academic)
    Abstract [en]

    Low-power wireless networks are quickly becoming a critical part of our everyday infrastructure. Power consumption is a critical concern, but power measurement and estimation is a challenge. We present Powertrace, which to the best of our knowledge is the first system for network-level power profiling of low-power wireless systems. Powertrace uses power state tracking to estimate system power consumption and a structure called energy capsules to attribute energy consumption to activities such as packet transmissions and receptions. With Powertrace, the power consumption of a system can be broken down into individual activities which allows us to answer questions such as “How much energy is spent forwarding packets for node X?”, “How much energy is spent on control traffic and how much on critical data?”, and “How much energy does application X account for?”. Experiments show that Powertrace is accurate to 94% of the energy consumption of a device. To demonstrate the usefulness of Powertrace, we use it to experimentally analyze the power behavior of the proposed IETF standard IPv6 RPL routing protocol and a sensor network data collection protocol. Through using Powertrace, we find the highest power consumers and are able to reduce the power consumption of data collection with 24%. It is our hope that Powertrace will help the community to make empirical energy evaluation a widely used tool in the low-power wireless research community toolbox.

  • 162.
    Dunkels, Adam
    et al.
    RISE, Swedish ICT, SICS.
    Eriksson, Joakim
    RISE, Swedish ICT, SICS, Computer Systems Laboratory.
    Tsiftes, Nicolas
    RISE, Swedish ICT, SICS, Computer Systems Laboratory.
    Low-power Interoperability for the IPv6-based Internet of Things2011Conference paper (Refereed)
    Abstract [en]

    The Internet of Things requires interoperability and low power consumption, but interoperability and low power consumption have thus far been mutually exclusive. This talk outlines the challenges in attaining low power operation for the IPv6-based Internet of Things, how this affects interoperability, and what must be done to combine the two.

  • 163.
    Dunkels, Adam
    et al.
    RISE, Swedish ICT, SICS.
    Feeney, Laura Marie
    RISE, Swedish ICT, SICS.
    Grönvall, Björn
    RISE, Swedish ICT, SICS.
    Voigt, Thiemo
    RISE, Swedish ICT, SICS, Computer Systems Laboratory.
    An integrated approach to developing sensor network solutions2004In: Proceedings of the Second International Workshop on Sensor and Actor Network Protocols and Applications, 2004, 1Conference paper (Refereed)
    Abstract [en]

    This paper describes a prototype sensor networking platform and its associated development environment. Key elements of the system are the ESB sensor hardware, the Contiki operating system, and the communication stack, which includes a MAC layer and a highly optimized TCP/IP. Because the work is driven by prototype applications being developed by project partners, particular attention is paid to the development environment and to practical deployment issues. Three prototype applications are also presented.

  • 164.
    Dunkels, Adam
    et al.
    RISE, Swedish ICT, SICS.
    Finne, Niclas
    RISE, Swedish ICT, SICS, Computer Systems Laboratory.
    Eriksson, Joakim
    RISE, Swedish ICT, SICS, Computer Systems Laboratory.
    Voigt, Thiemo
    RISE, Swedish ICT, SICS, Computer Systems Laboratory.
    Reprogramming wireless sensor networks with run-time dynamic linking in Contiki.2007In: Proceedings of Real-Time in Sweden 2007, 2007, 1Conference paper (Refereed)
  • 165.
    Dunkels, Adam
    et al.
    RISE, Swedish ICT, SICS.
    Finne, Niclas
    RISE, Swedish ICT, SICS, Computer Systems Laboratory.
    Eriksson, Joakim
    RISE, Swedish ICT, SICS, Computer Systems Laboratory.
    Voigt, Thiemo
    RISE, Swedish ICT, SICS, Computer Systems Laboratory.
    Run-time dynamic linking for reprogramming wireless sensor networks2006Conference paper (Refereed)
    Abstract [en]

    From experience with wireless sensor networks it has become apparent that dynamic reprogramming of the sensor nodes is a useful feature. The resource constraints in terms of energy, memory, and processing power make sensor network reprogramming a challenging task. Many different mechanisms for reprogramming sensor nodes have been developed ranging from full image replacement to virtual machines. We have implemented an in-situ run-time dynamic linker and loader that use the standard ELF object file format. We show that run-time dynamic linking is an effective method for reprogramming even resource constrained wireless sensor nodes. To evaluate our dynamic linking mechanism we have implemented an application-specific virtual machine and a Java virtual machine and compare the energy cost of the different linking and execution models. We measure the energy consumption and execution time overhead on real hardware to quantify the energy costs for dynamic linking. Our results suggest that while in general the overhead of a virtual machine is high, a combination of native code and virtual machine code provide good energy efficiency. Dynamic run-time linking can be used to update the native code, even in heterogeneous networks.

  • 166.
    Dunkels, Adam
    et al.
    RISE, Swedish ICT, SICS.
    Grönvall, Björn
    Voigt, Thiemo
    RISE, Swedish ICT, SICS, Computer Systems Laboratory.
    Contiki - a Lightweight and Flexible Operating System for Tiny Networked Sensors2004In: Proceedings of the First IEEE Workshop on Embedded Networked Sensors, 2004, 1Conference paper (Refereed)
    Abstract [en]

    Wireless sensor networks are composed of large numbers of tiny networked devices that communicate untethered. For large scale networks it is important to be able to dynamically download code into the network. In this paper we present Contiki, a lightweight operating system with support for dynamic loading and replacement of individual programs and services. Contiki is built around an event-driven kernel but provides optional preemptive multithreading that can be applied to individual processes. We show that dynamic loading and unloading is feasible in a resource constrained environment, while keeping the base system lightweight and compact.

  • 167.
    Dunkels, Adam
    et al.
    RISE, Swedish ICT, SICS.
    Grönvall, Björn
    RISE - Research Institutes of Sweden, ICT, SICS.
    Voigt, Thiemo
    RISE, Swedish ICT, SICS, Computer Systems Laboratory.
    Alonso, Juan
    RISE - Research Institutes of Sweden, ICT, SICS.
    The Design of a Lightweight Portable Operating System for Tiny Networked Sensor Devices2004Report (Other academic)
    Abstract [en]

    Wireless sensor networks are composed of large numbers of tiny networked devices that communicate untethered. In this paper we present the design of Contiki, a lightweight and portable operating system for such tiny devices. In this work, we try to find the right operating system abstractions that enable dynamic and efficient operation of a system with severe limitations. Contiki is built around a lightweight event scheduler and provides suitable abstractions for dynamic loading of programs, device drivers, and run-time linking of libraries. The system is highly portable and the kernel can be ported without changing a single line of code (except device drivers). We show how higher level abstractions such as multi-threading can be implemented as libraries on top of the lightweight event kernel.

  • 168.
    Dunkels, Adam
    et al.
    RISE, Swedish ICT, SICS, Computer Systems Laboratory.
    Mottola, Luca
    RISE, Swedish ICT, SICS, Computer Systems Laboratory.
    Tsiftes, Nicolas
    RISE, Swedish ICT, SICS, Computer Systems Laboratory.
    Österlind, Fredrik
    RISE, Swedish ICT, SICS.
    Eriksson, Joakim
    RISE, Swedish ICT, SICS, Computer Systems Laboratory.
    Finne, Niclas
    RISE, Swedish ICT, SICS, Computer Systems Laboratory.
    The Announcement Layer: Beacon Coordination for the Sensornet Stack2011Conference paper (Refereed)
  • 169.
    Dunkels, Adam
    et al.
    RISE, Swedish ICT, SICS.
    Schmidt, Oliver
    Voigt, Thiemo
    RISE, Swedish ICT, SICS, Computer Systems Laboratory.
    Using Protothreads for Sensor Node Programming2005In: Proceedings of the REALWSN'05 Workshop on Real-World Wireless Sensor Networks, 2005, 1Conference paper (Refereed)
    Abstract [en]

    Wireless sensor networks consist of tiny devices that usually have severe resource constraints in terms of energy, processing power and memory. In order to work efficiently within the constrained memory, many operating systems for such devices are based on an event-driven model rather than on multi-threading. While event-driven systems allow for reduced memory usage, they require programs to be developed as explicit state machines. Since implementing programs as explicit state machines is hard, developing, maintaining, and debugging programs for event-driven systems is difficult. In this paper, we introduce protothreads, a programming abstraction for event-driven sensor network systems. Protothreads simplify implementation of high-level functionality on top of event-driven systems, without significantly increasing the memory requirements. The memory requirement of a protothread is that of an unsigned integer.

  • 170.
    Dunkels, Adam
    et al.
    RISE, Swedish ICT, SICS.
    Schmidt, Oliver
    Voigt, Thiemo
    RISE, Swedish ICT, SICS, Computer Systems Laboratory.
    Ali, Muneeb
    Protothreads: simplifying event-driven programming of memory-constrained embedded systems2006Conference paper (Refereed)
    Abstract [en]

    Event-driven programming is a popular model for writing programs for tiny embedded systems and sensor network nodes. While event-driven programming can keep the memory overhead down, it enforces a state machine programming style which makes many programs difficult to write, maintain, and debug. We present a novel programming abstraction called protothreads that makes it possible to write event-driven programs in a thread-like style, with a memory overhead of only two bytes per protothread. We show that protothreads significantly reduce the complexity of a number of widely used programs previously written with event-driven state machines. For the examined programs the majority of the state machines could be entirely removed. In the other cases the number of states and transitions was drastically decreased. With protothreads the number of lines of code was reduced by one third. The execution time overhead of protothreads is on the order of a few processor cycles.

  • 171.
    Dunkels, Adam
    et al.
    RISE, Swedish ICT, SICS.
    Voigt, Thiemo
    RISE, Swedish ICT, SICS, Computer Systems Laboratory.
    Alonso, Juan
    Connecting wireless sensor networks with the internet2004In: ERCIM News, ISSN 0926-4981, E-ISSN 1564-0094, no 57Article in journal (Refereed)
  • 172.
    Dunkels, Adam
    et al.
    RISE, Swedish ICT, SICS.
    Voigt, Thiemo
    RISE, Swedish ICT, SICS, Computer Systems Laboratory.
    Alonso, Juan
    RISE, Swedish ICT, SICS.
    Making TCP/IP Viable for Wireless Sensor Networks2004Conference paper (Refereed)
    Abstract [en]

    The TCP/IP protocol suite, which has proven itself highly successful in wired networks, is often claimed to be unsuited for wireless micro-sensor networks. In this work, we question this conventional wisdom and present a number of mechanisms that are intended to enable the use of TCP/IP for wireless sensor networks: spatial IP address assignment, shared context header compression, application overlay routing, and distributed TCP caching (DTC). Sensor networks based on TCP/IP have the advantage of being able to directly communicate with an infrastructure consisting either of a wired IP network or of IP-based wireless technology such as GPRS. We have implemented parts of our mechanisms both in a simulator environment and on actual sensor nodes, and preliminary results are promising.

  • 173.
    Dunkels, Adam
    et al.
    RISE, Swedish ICT, SICS.
    Voigt, Thiemo
    RISE, Swedish ICT, SICS, Computer Systems Laboratory.
    Alonso, Juan
    RISE, Swedish ICT, SICS.
    Ritter, Hartmut
    Distributed tcp caching for wireless sensor networks2004Conference paper (Refereed)
  • 174.
    Dunkels, Adam
    et al.
    RISE, Swedish ICT, SICS.
    Voigt, Thiemo
    RISE, Swedish ICT, SICS, Computer Systems Laboratory.
    Alonso, Juan
    RISE, Swedish ICT, SICS.
    Ritter, Hartmut
    Schiller, Jochen
    Connecting Wireless Sensornets with TCP/IP Networks.2004Conference paper (Refereed)
  • 175.
    Dunkels, Adam
    et al.
    RISE, Swedish ICT, SICS.
    Voigt, Thiemo
    RISE, Swedish ICT, SICS, Computer Systems Laboratory.
    Alonso, Juan
    RISE - Research Institutes of Sweden, ICT, SICS.
    Ritter, Hartmut
    Schiller, Jochen
    Connecting Wireless Sensornets with TCP/IP Networks2003Report (Other academic)
    Abstract [en]

    Wireless sensor networks are based on the collaborative efforts of many small wireless sensor nodes, which collectively are able to form networks through which sensor information can be gathered. Such networks usually cannot operate in complete isolation, but must be connected to an external network to which monitoring and controlling entities are connected. As TCP/IP, the Internet protocol suite, has become the de-facto standard for large-scale networking, it is interesting to be able to connect sensornets to TCP/IP networks. In this paper, we discuss three different ways to connect sensor networks with TCP/IP networks: proxy architectures, DTN overlays, and TCP/IP for sensor networks. We conclude that the methods are in some senses orthogonal and that combinations are possible, but that TCP/IP for sensor networks currently has a number of issues that require further research before TCP/IP can be a viable protocol family for sensor networking.

  • 176.
    Dunkels, Adam
    et al.
    RISE, Swedish ICT, SICS.
    Voigt, Thiemo
    RISE, Swedish ICT, SICS, Computer Systems Laboratory.
    Bergman, Niclas
    Jönsson, Mats
    The design and implementation of an IP-based sensor network for intrusion monitoring2004Conference paper (Refereed)
  • 177.
    Dunkels, Adam
    et al.
    RISE, Swedish ICT, SICS.
    Österlind, Fredrik
    RISE, Swedish ICT, SICS.
    He, Zhitao
    RISE, Swedish ICT, SICS, Computer Systems Laboratory.
    An Adaptive Communication Architecture for Wireless Sensor Networks2007In: Proceedings of the 5th ACM Conference on Embedded Networked Sensor Systems, ACM Press , 2007, 1, , p. 14Conference paper (Refereed)
  • 178.
    Dunkels, Adam
    et al.
    RISE - Research Institutes of Sweden, ICT, SICS.
    Österlind, Fredrik
    RISE, Swedish ICT, SICS.
    Tsiftes, Nicolas
    RISE, Swedish ICT, SICS, Computer Systems Laboratory.
    IP-based sensor networks: a hands-on tutorial2009Conference paper (Refereed)
    Abstract [en]

    IP-based sensor networks are a rapidly emerging hot topic in both academia and the industry. The open source uIP stack from the Contiki operating system, first released in 2001, is used in IP-enabled products and systems from hundreds of companies, ranging from pico-satellites, airplanes, and car engines, to worldwide freighter container tracking systems, ship control systems, and oil boring and pipeline monitoring systems. In October 2008 Cisco Systems released uIPv6, the world's smallest fully compliant IPv6 stack, for Contiki. During this tutorial, participants will get started with building IP-based sensor networks with Contiki and uIP, and get hands-on experience with developing, compiling, and running IP-based software on sensornet hardware, setting up IP networking to the sensor network, and getting performance metrics (power, throughput, latency) from a running network. We use a combination of Tmote Sky and Sentilla JCreate motes as the hardware platform. We provide Tmote Skys and JCreates for participants to borrow during the tutorial. To avoid installation of compilers and tools, participants will use the Instant Contiki development environment, a complete development environment in a single-file download consisting of a VMWare virtual machine with all Contiki software development tools installed: http://www.sics.se/contiki/instant-contiki.html

  • 179.
    Dunkels, Adam
    et al.
    RISE, Swedish ICT, SICS.
    Österlind, Fredrik
    RISE, Swedish ICT, SICS.
    Tsiftes, Nicolas
    RISE, Swedish ICT, SICS, Computer Systems Laboratory.
    He, Zhitao
    RISE, Swedish ICT, SICS, Computer Systems Laboratory.
    Demo abstract: Software-based sensor node energy estimation2007Conference paper (Refereed)
    Abstract [en]

    Being able to estimate the energy consumption of sensor nodes is essential both for evaluating existing sensor network mechanisms and for constructing new energy-aware mechanisms. We present a software-based mechanism for estimating the energy consumption of sensor node at run-time. Unlike previous energy estimation mechanisms, our mechanism does not require any additional hardware components or add-ons. Our demonstration shows the energy estimation in practice on a small network of Tmote Sky motes running the Contiki operating system. A PC connected to one of the motes shows the real-time energy estimation of the network nodes and where the energy is spent: CPU active, CPU sleeping, radio transmitting, radio listening, and LEDs

  • 180.
    Dunkels, Adam
    et al.
    RISE, Swedish ICT, SICS.
    Österlind, Fredrik
    RISE, Swedish ICT, SICS.
    Tsiftes, Nicolas
    RISE, Swedish ICT, SICS, Computer Systems Laboratory.
    He, Zhitao
    RISE, Swedish ICT, SICS, Computer Systems Laboratory.
    Software-based on-line energy estimation for sensor nodes2007In: Proceedings of the Fourth Workshop on Embedded Networked Sensors (Emnets IV), 2007, 1, , p. 5Conference paper (Refereed)
    Abstract [en]

    Energy is of primary importance in wireless sensor networks. By being able to estimate the energy consumption of the sensor nodes, applications and routing protocols are able to make informed decisions that increase the lifetime of the sensor network. However, it is in general not possible to measure the energy consumption on popular sensor node platforms. In this paper, we present and evaluate a softwarebased on-line energy estimation mechanism that estimates the energy consumption of a sensor node. We evaluate the mechanism by comparing the estimated energy consumption with the lifetime of capacitor-powered sensor nodes. By implementing and evaluating the X-MAC protocol, we show how software-based on-line energy estimation can be used to empirically evaluate the energy efficiency of sensor network protocols.

  • 181.
    Duquennoy, Simon
    et al.
    RISE, Swedish ICT, SICS, Computer Systems Laboratory.
    Landsiedel, Olaf
    Poster Abstract: Opportunistic RPL2013Conference paper (Refereed)
    Abstract [en]

    Sensor nodes constituting Wireless Sensor Networks (WSN) are often battery- operated and have limited resources. To save energy, nodes sleep most of the time, and wake up periodically to handle communication. Such radio duty cycling poses a basic trade-off between energy and latency. In previous work, we have shown that opportunistic routing is an efficient way to achieve low-latency yet energy efficient data collection in WSN (ORW [3]). In this paper, we extend this approach to the context of low-power IP networks, where nodes need to be addressed individually and where traffic patterns are irregular. We present ORPL, an opportunistic extension of RPL, the stan- dard, state-of-the-art routing protocol for low-power IP networks. We discuss our preliminary results obtained with Contiki in a 137-node testbed.

  • 182.
    Duquennoy, Simon
    et al.
    RISE, Swedish ICT, SICS, Computer Systems Laboratory.
    Landsiedel, Olaf
    Voigt, Thiemo
    RISE, Swedish ICT, SICS, Computer Systems Laboratory.
    Let the Tree Bloom: Scalable Opportunistic Routing with ORPL2013Conference paper (Refereed)
  • 183.
    Duquennoy, Simon
    et al.
    RISE, Swedish ICT, SICS, Computer Systems Laboratory.
    Wirström, Niklas
    RISE, Swedish ICT, SICS.
    Dunkels, Adam
    RISE, Swedish ICT, SICS.
    Demo: Snap – Rapid Sensornet Deployment with a Sensornet Appstore2011Conference paper (Refereed)
    Abstract [en]

    Despite ease of deployment being seen as a primary advantage of sensor networks, deployment remains difficult. We present Snap, a system for rapid sensornet deployment that allows sensor networks to be deployed, positioned, and reprogrammed through a sensornet appstore. Snap uses a smartphone interface that uses QR codes for node identification, a map interface for node positioning, and dynamic loading of applications on the nodes. Snap nodes run the Contiki operating system and its low-power IPv6 network stack that provides direct access from nodes to the smartphone application. We demonstrate rapid sensor node deployment, identification, positioning, and node reprogramming within seconds, over a multi-hop sensornet routing path with a WiFi-connected smartphone.

  • 184.
    Duquennoy, Simon
    et al.
    RISE, Swedish ICT, SICS, Computer Systems Laboratory.
    Wirström, Niklas
    RISE, Swedish ICT, SICS.
    Tsiftes, Nicolas
    RISE, Swedish ICT, SICS, Computer Systems Laboratory.
    Dunkels, Adam
    RISE, Swedish ICT, SICS.
    Leveraging IP for Sensor Network Deployment2011Conference paper (Refereed)
  • 185.
    Duquennoy, Simon
    et al.
    RISE, Swedish ICT, SICS, Computer Systems Laboratory.
    Österlind, Fredrik
    RISE, Swedish ICT, SICS.
    Dunkels, Adam
    RISE, Swedish ICT, SICS.
    Lossy Links, Low Power, High Throughput2011Conference paper (Refereed)
    Abstract [en]

    As sensor networks move towards general-purpose low-power wireless networks, there is a need to support both traditional low-data rate traffic and high-throughput transfer. To attain high throughput, existing protocols monopolize the network resources and keep the radio on for all nodes involved in the transfer, leading to poor energy efficiency. This becomes progressively problematic in networks with packet loss, which inevitably occur in any real-world deployment. We present burst forwarding, a generic packet forwarding technique that combines low power consumption with high throughput for multi-purpose wireless networks. Burst forwarding uses radio duty cycling to maintain a low power consumption, recovers efficiently from interference, and inherently supports both single streams and cross-traffic. We experimentally evaluate our mechanism under heavy interference and compare it to PIP, a state-of-the-art sensornet bulk transfer protocol. Burst forwarding gracefully adapts radio duty cycle both to the level of interference and to traffic load, keeping a low and nearly constant energy cost per byte when carrying TCP traffic.

  • 186. Durvy, Mathilde
    et al.
    Abeillé, Julien
    Wetterwald, Patrick
    O'Flynn, Colin
    Leverett, Blake
    Gnoske, Eric
    Vidales, Michael
    Mulligan, Geoff
    Tsiftes, Nicolas
    RISE, Swedish ICT, SICS, Computer Systems Laboratory.
    Finne, Niclas
    RISE, Swedish ICT, SICS, Computer Systems Laboratory.
    Dunkels, Adam
    RISE - Research Institutes of Sweden, ICT, SICS.
    Making sensor networks IPv6 ready2008In: Proceedings of the Sixth ACM Conference on Networked Embedded Sensor Systems (ACM SenSys 2008), 2008, 1Conference paper (Refereed)
    Abstract [en]

    With emerging IPv6-based standards such as 6LowPAN and ISA- 100a, full IPv6 sensor networks are the next major step. With millions of deployed embedded IPv6 devices, interoperability is of major importance, both within the sensor networks and between the sensors and the Internet hosts. We present uIPv6, the first IPv6 stack for memory-constrained devices that passes all Phase-1 IPv6 Ready certification tests. This is an important step for end-to-end interoperability between IPv6 sensors and any IPv6 capable device. To allow widespread community adoption, we release uIPv6 under a permissive open source license that allows both commercial and non-commercial use.

  • 187. Ekelin, Svante
    et al.
    Nilsson, Martin
    RISE, Swedish ICT, SICS, Computer Systems Laboratory.
    Continuous monitoring of available bandwidth over a network path2004Conference paper (Refereed)
  • 188. Ekelin, Svante
    et al.
    Nilsson, Martin
    RISE, Swedish ICT, SICS, Computer Systems Laboratory.
    The Failure of 'The Failure of Poisson Modeling' for Internet Bandwidth Measurements2005Conference paper (Refereed)
    Abstract [en]

    There is a classic paper, which claims that many parameters of network traffic are best modeled by stochastic distributions with infinite variance. We believe that although this paper is correct, it has commonly been overinterpreted. It is true that some distributions have infinite variance, but not all. There are important cases where distributions of traffic parameters have finite variance. As an example, we show that the end-to-end available bandwidth must have finite variance, outline a method for measuring it, and present some experimental data.

  • 189. Ekelin, Svante
    et al.
    Nilsson, Martin
    RISE, Swedish ICT, SICS, Computer Systems Laboratory.
    Hartikainen, Erik
    Johnsson, Andreas
    Mångs, Jan-Erik
    Melander, Bob
    Björkman, Mats
    Real-time measurement of end-to-end available bandwidth using Kalman filtering2006Conference paper (Refereed)
    Abstract [en]

    This paper presents a new method, BART (Bandwidth Available in Real-Time), for estimating the end-to-end available bandwidth over a network path. It estimates bandwidth quasi-continuously, in real-time. The method has also been implemented as a tool. It relies on self-induced congestion, and probes the network path with trains of probe packets, sent at randomized rates. BART requires little computation in each iteration, is light-weight with respect to memory requirements, and adds only a small amount of probe traffic. The BART method is based on Kalman filtering, which enables real-time estimation (a.k.a. tracking) with optimum performance under general conditions. It maintains a current estimate, which is incrementally improved with each new measurement of the inter-packet time separations in a probe packet train. The measurement model has a strong non-linearity, and would not at first sight be considered suitable for Kalman filtering, but we show how this non-linearity can be handled. BART may be tuned according to the specific needs of the measurement application, such as agility vs. stability of the estimate, and the desired time-scale on which to track traffic fluctuations. We have tested BART in a physical test network with carefully controlled cross traffic, with good accuracy and agreement. Test measurements have also been performed over the Internet. We compare the performance of BART with that of pathChirp, a state-of-the-art tool for measuring end-to-end available bandwidth in real-time.

  • 190.
    El-Ansary, Sameh
    RISE, Swedish ICT, SICS, Computer Systems Laboratory.
    Structured peer-to-peer systems: the impact of lawyers and music piracy on distributed systems research2003In: ERCIM News, ISSN 0926-4981, E-ISSN 1564-0094, Vol. 55Article in journal (Refereed)
    Abstract [en]

    What started out as an initiative for music piracy evolved into an interesting research area in distributed systems, due to reasons that were not mainly technical but rather legal.

  • 191. El-Ansary, Sameh
    et al.
    Aurell, Erik
    Brand, Per
    RISE, Swedish ICT, SICS, Computer Systems Laboratory.
    Haridi, Seif
    RISE, Swedish ICT, SICS, Computer Systems Laboratory.
    Experience with a physics-style approach for the study of self properties in structured overlay networks2004Conference paper (Refereed)
  • 192.
    El-Ansary, Sameh
    et al.
    RISE, Swedish ICT, SICS.
    Brand, Per
    RISE, Swedish ICT, SICS.
    Haridi, Seif
    RISE, Swedish ICT, SICS, Computer Systems Laboratory.
    Efficient broadcast in structured P2P networks2003Conference paper (Refereed)
    Abstract [en]

    In this position paper, we present an efficient algorithm for performing a broadcast operation with minimal cost in structured DHT-based P2P networks. In a system of N nodes, a broadcast message originating at an arbitrary node reaches all other nodes after exactly N-1 messages. We emphasize the perception of a class of DHT systems as a form of distributed k-ary search and we take advantage of that perception in constructing a spanning tree that is utilized for efficient broadcasting. We consider broadcasting as a basic service that adds to existing DHTs the ability to search using arbitrary queries as well as dissiminate/collect global information.

  • 193.
    El-Ansary, Sameh
    et al.
    RISE, Swedish ICT, SICS, Computer Systems Laboratory.
    Grolaux, Donatien
    Van Roy, Peter
    Rafea, Mahmoud
    Overcoming the multiplicity of languages and technologies for web-based development using a multi-paradigm approach2004Conference paper (Refereed)
  • 194.
    Elsts, Atis
    et al.
    RISE, Swedish ICT, SICS. University of Bristol, UK.
    Duquennoy, Simon
    RISE, Swedish ICT, SICS, Computer Systems Laboratory. Inria, France.
    Fafoutis, Xenofon
    University of Bristol, UK.
    Oikonomou, George
    University of Bristol, UK.
    Piechocki, Robert
    University of Bristol, UK.
    Craddock, Ian
    University of Bristol, UK.
    Microsecond-Accuracy Time Synchronization Using the IEEE 802.15.4 TSCH Protocol2016In: Proceedings of the International Workshop on Practical Issues in Building Sensor Network Applications (IEEE SenseApp 2016), 2016, 8Conference paper (Refereed)
    Abstract [en]

    Time-Slotted Channel Hopping from the IEEE 802.15.4-2015 standard requires that network nodes are tightly time-synchronized. Existing implementations of TSCH on embedded hardware are characterized by tens-of-microseconds large synchronization errors; higher synchronization accuracy would enable reduction of idle listening time on receivers, in this way decreasing the energy required to run TSCH. For some applications, it would also allow to replace dedicated time synchronization mechanisms with TSCH. We show that time synchronization errors in the existing TSCH implementations on embedded hardware are caused primarily by imprecise clock drift estimations, rather than by real unpredictable drift variance. By estimating clock drift more precisely and by applying adaptive time compensation on each node in the network, we achieve microsecond accuracy time synchronization on point-to-point links and a < 2 µs end-to-end error in a 7- node line topology. Our solution is implemented in the Contiki operating system and tested on Texas Instruments CC2650- based nodes, equipped with common off-the-shelf hardware clock sources (±20 ppm drift). Our implementation uses only standard TSCH control messages and is able to keep radio duty cycle below 1 %.

  • 195.
    Elvitigala, Charitha
    et al.
    University of Colombo School of Computing, Sri Lanka.
    Tennakoon, Eranda
    University of Colombo School of Computing, Sri Lanka.
    Hamza, Ayyoob
    University of Colombo School of Computing, Sri Lanka.
    Lokuge, Yasith
    University of Colombo School of Computing, Sri Lanka.
    De Zoysa, Kasun
    University of Colombo School of Computing, Sri Lanka.
    Keppitiyagama, Chamath
    RISE, Swedish ICT, SICS. University of Colombo School of Computing, Sri Lanka.
    Iyer, Venkatraman
    Uppsala University, Sweden.
    Hewage, Kasun
    Uppsala University, Sweden.
    Voigt, Thiemo
    RISE, Swedish ICT, SICS, Computer Systems Laboratory. Uppsala University, Sweden.
    Towards a sensor system to tame the human elephant conflict2015In: 2015 IEEE Sensors Applications Symposium (SAS), 2015, 9, article id 7133595Conference paper (Refereed)
    Abstract [en]

    The human elephant conflict in Sri Lanka has been a cause of major concern over the past decade. Frequent clashes between wild elephants and villagers have resulted in severe damage to property, as well as loss of lives for both humans and elephants. Competition for space is the primary reason for conflict between humans and elephants. Elephants that escape from the wildlife national parks venture into villages creating destruction in their wake. To prevent such mishaps, a proper system is required to contain and monitor elephants in national parks. In this paper, we describe different approaches to detect elephants and possible ways of monitoring the national wildlife parks. We also elaborate on the advantages and limitations of each approach, and determine what sort of system is needed to tame the human elephant conflict.

  • 196.
    Eriksson, Joakim
    et al.
    RISE, Swedish ICT, SICS, Computer Systems Laboratory.
    Dunkels, Adam
    RISE, Swedish ICT, SICS.
    Finne, Niclas
    RISE, Swedish ICT, SICS, Computer Systems Laboratory.
    Österlind, Fredrik
    RISE, Swedish ICT, SICS.
    Voigt, Thiemo
    RISE, Swedish ICT, SICS, Computer Systems Laboratory.
    Mspsim - an extensible simulator for msp430-equipped sensor boards.2007Conference paper (Refereed)
  • 197.
    Eriksson, Joakim
    et al.
    RISE, Swedish ICT, SICS, Computer Systems Laboratory.
    Dunkels, Adam
    RISE - Research Institutes of Sweden, ICT, SICS.
    Finne, Niclas
    RISE, Swedish ICT, SICS, Computer Systems Laboratory.
    Österlind, Fredrik
    RISE - Research Institutes of Sweden, ICT, SICS.
    Voigt, Thiemo
    RISE, Swedish ICT, SICS, Computer Systems Laboratory.
    Tsiftes, Nicolas
    RISE, Swedish ICT, SICS, Computer Systems Laboratory.
    Demo abstract: MSPsim - an extensible simulator for MSP430-equipped sensor boards2008Conference paper (Refereed)
  • 198.
    Eriksson, Joakim
    et al.
    RISE, Swedish ICT, SICS, Computer Systems Laboratory.
    Finne, Niclas
    RISE, Swedish ICT, SICS, Computer Systems Laboratory.
    Janson, Sverker
    RISE, Swedish ICT, SICS, Computer Systems Laboratory.
    Evolution of a supply chain management game for the trading agent competition2006In: AI Communications, Vol. 19, p. 1-12Article in journal (Refereed)
    Abstract [en]

    TAC SCM is a supply chain management game for the Trading Agent Competition (TAC). The purpose of TAC is to spur high quality research into realistic trading agent problems. We discuss TAC and TAC SCM: game and competition design, scientific impact, and lessons learnt.

  • 199.
    Eriksson, Joakim
    et al.
    RISE, Swedish ICT, SICS, Computer Systems Laboratory.
    Finne, Niclas
    RISE, Swedish ICT, SICS, Computer Systems Laboratory.
    Janson, Sverker
    RISE, Swedish ICT, SICS, Computer Systems Laboratory.
    SICS MarketSpace: an agent-based market infrastructure1998Conference paper (Refereed)
    Abstract [en]

    We present a simple and uniform communication framework for an agent-based market infrastructure, the goal of which is to enable automation of markets with self-interested participants distributed over the Internet.

  • 200.
    Eriksson, Joakim
    et al.
    RISE, Swedish ICT, SICS, Computer Systems Laboratory.
    Finne, Niclas
    RISE, Swedish ICT, SICS, Computer Systems Laboratory.
    Janson, Sverker
    RISE, Swedish ICT, SICS, Computer Systems Laboratory.
    To each and everyone an agent: augmenting web-based commerce with agents1998Conference paper (Refereed)
1234567 151 - 200 of 601
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