Jörg Nolte

Brandenburg University of Technology Cottbus - Senftenberg, Kottbus, Brandenburg, Germany

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Publications (44)9.28 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Currently, new storage technologies which unite the latency and byte-addressability of DRAM with the persistence of disks are being developed. This non-volatile memory (NV-RAM) may start a software revolution. Traditionally, software was developed for two levels of storage and NVRAM reduces the hierarchy to a single-level store. Current research projects are already exploring the potential of NVRAM, but they face a challenge when they want to evaluate the performance: The new hardware is not yet available. In this paper, we discuss why benchmark results which are gained on existing DRAM are insufficient for a prediction of the performance on NVRAM. Either existing instructions have to be changed or new ones have to be introduced. We further show that the bochs emulator can be used to build systems which resemble NVRAM, to predict the NVRAM’s consequences, and it even allows a comparison of algorithms for NVRAM.
    No preview · Conference Paper · Jan 2014
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    ABSTRACT: Experiments with wireless sensor networks have shown that asymmetric and unidirectional links are common. For this reason, we developed different routing protocols that can use unidirectional links, either implicitly or explicitly. However, developing protocols that use unidirectional links is difficult, not least because of inadequate simulation support. In this paper we present a simulation model based on OMNeT++ and MiXiM that we developed to simulate networks with unidirectional links and frequent link changes. We evaluate the developed simulation approach by comparison of results achieved by different routing protocols in simulation and in experiments with real sensor network hardware.
    No preview · Conference Paper · Jan 2014
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    ABSTRACT: Self-stabilizing algorithms (SSA) are defined on the assumption that either the system’s topology is fixed over time or topology changes are isolated events occurring at a very low rate. These assumptions are not valid in wireless sensor networks (WSNs) where link qualities change rapidly. The contribution of this paper is a neighborhood management protocol (NMP) providing a neighborhood relation sufficiently stable to apply existing SSAs in WSNs.
    No preview · Chapter · Nov 2013
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    ABSTRACT: On many-core processors that do not provide hard-ware cache coherence, using shared memory in parallel com-putations is challenging. Reverting to pure message passing would avoid consistency issues, but replicating large shared datasets by messages is less efficient than accessing them di-rectly through shared memory. The TACO-MESH framework provides lightweight remote method calls and shared objects with software-managed consistency. This paper presents experience from porting a graph partitioning algorithm to the framework. A performance evaluation on the experimental Intel SCC pro-cessor, which has no hardware cache coherence, shows that parallelization can be efficient despite the overhead of software-level consistency management.
    Preview · Article · Jul 2012
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    Stefan Lohs · Reinhardt Karnapke · Jörg Nolte
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    ABSTRACT: Most routing protocols proposed for wireless sensor networks are based on the standard approach also used in many other types of networks, e.g. MANETS, even though the conditions are drastically different. To evaluate the usefulness of reactive routing protocols based on route discovery by flooding of route request messages it is necessary to understand the nature of the underlying wireless communication links. In this work we present the results of connectivity measurements conducted with current sensor node hardware, taking special interest in the number of unidirectional links present and the frequency of link changes.
    Preview · Article · Jun 2012
  • Andre Sieber · Joerg Nolte
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    ABSTRACT: Energy and run time are mayor concerns in wireless sensor networks. Reliable information about the energy consumption is needed to be able to build a network and tune its application. In this paper we take a look on the energy consumption of the Texas Instruments eZ430-Chronos, an MSP430 based wireless sensor node, and compare it to the manufacturers datasheet. The measurements show how reliable these specifications are and which consequences should be taken.
    No preview · Conference Paper · Jan 2012
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    Thomas Prescher · Randolf Rotta · Jörg Nolte
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    ABSTRACT: The SCC (Single-Chip Cloud Computer) is an experimental 48-core concept vehicle created by Intel Labs and does, deliberately, not provide hardware-implemented cache coherence. It can be treated like a distributed memory system by implementing data replication and consistency control based on message passing. However, the SCC still is a shared memory system with shared access to parts of the memory. Thus, replicating data for every core wastes memory and is inefficient as well, because most replica updates go from and to the same memory device. This paper presents a framework for memory efficient sharing on such distributed systems with shared memory subsystems. It is adaptable in respect to the underlying memory architecture (with and without hardware cache coherence) as well as the employed sharing models (e.g. central instance, replicas with various consistency models, and hybrids of both). This is achieved by dividing the replica management into storage containers (for shared data on each memory device) and control containers (for consistency and cache control on each core). The framework's design shows that it is possible to combine different sharing and communication paradigms to exploit hybrid many-core architectures up to clusters of SCCs.
    Preview · Article · Jan 2012
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    ABSTRACT: A lot of applications for wireless sensor networks have been proposed in the last years. Only a few of them have led to real, non-academic deployments, partially due to the differences between end user needs and academic assumptions. In this paper we discuss a real world problem arising from an ecological question (protection of an endangered species) and the theoretical solution as well as the deployed solution that actually works.
    Preview · Conference Paper · Jan 2011
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    ABSTRACT: Communication neighborhood in wireless sensor networks changes often as links break or appear. Therefore, monitoring link quality and (logical) network topology is necessary. As node placement has a large influence on the radio neighborhood and its changes, different positions should be evaluated before starting the actual application. In this paper we introduce Sensorium, an active monitoring system that supplies the user with an insight into the neighborhood relations between nodes and their changes in time. It can be used before the actual deployment to evaluate different possibilities of node placement and choose the one that offers the best connectivity.
    Preview · Conference Paper · Aug 2010
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    David Peters · Reinhardt Karnapke · Jörg Nolte
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    ABSTRACT: Experiments with wireless sensor networks have shown that unidirectional communication links are quite common. What is even more, they have also shown that the range of a unidirectional link can exceed that of a bidirectional one by far. Still, most of todays routing protocols do not use them, they only eliminate their implications. Those protocols that do use unidirectional links introduce a lot of protocol over- head. In this paper we present Buckshot Routing, a robust, yet simple source routing protocol for dense wireless networks with lossy or unidi- rectional links, which reduces the overhead generated by route discovery and route maintenance signicantly.
    Preview · Conference Paper · Sep 2009
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    Stephan Mank · Reinhardt Karnapke · Joerg Nolte
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    ABSTRACT: Unidirectional links are a common property of all wireless networks. In many cases, the range of these links exceeds that of bidirectional links by far. Still, most protocols ignore their existence or simply discard them. In this paper we introduce two new medium access control (MAC) protocols called MLMAC-UL and ECTS-MAC that are able to transmit data over unidirectional links and receive acknowledgment messages for them using a neighborhood discovery protocol. Both protocols, as well as two reference protocols, were evaluated in simulations and using a real sensor network consisting of TMote Sky sensor nodes.
    Preview · Conference Paper · Jul 2009
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    ABSTRACT: Energy consumption is a crucial factor for the lifetime of many embedded systems, especially wireless sensor networks. Most modern microcontrollers provide various low power sleep modes. Utilizing them can lead to great energy savings. In this paper we present an approach for power management in embedded systems, based on the event-driven operating system Reflex. The implicit power management is mostly hardware independent, lightweight and efficiently chooses the optimal power saving mode of the microprocessor automatically.
    No preview · Conference Paper · May 2009
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    ABSTRACT: Wireless sensor networks operate in an unstable envi-ronment and thus are subject to arbitrary transient faults. Self-stabilization is a promising technique to add tolerance against transient faults in a self-contained non-masking way. A core factor for the applicability of a given self-stabilizing algorithm is its convergence time. This paper analyses the average stabilization time of three algorithms commonly regarded as central building blocks for wireless sensor networks. The analysis is accomplished with Self-WISE, a framework providing programming abstractions for self-stabilizing algorithms. The performed analysis con-siders the target models as well as network size and density. This demonstrates the usability of SelfWISE for evaluating self-stabilizing algorithms under a wide range of models.
    Full-text · Article · Jan 2009
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    Sören Höckner · Andreas Lagemann · Jörg Nolte
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    ABSTRACT: Developing wireless sensor network (WSN) applications is a challenging task. Simulations are a key component in the development process, since they oer simple means of testing and evaluating the applications without the need of time consuming and tedious deployment. But simulations alone are not sucient to evaluate such applications. Only experiments on real hardware can ultimately verify the cor- rectness of a given algorithm and its implementation. To take the most benet from a WSN simulator it must be able to simulate a sensor network, where all nodes run the same implementation of the algorithm that will later be deployed. We show how to integrate event-driven operating systems into the OMNeT++ discrete event simulator. At the ex- ample of Reflex we show how an integration can be easily achieved with minor eort. Additionally we discuss an alter- native approach which promises better scalability but comes at the cost of less exibility at the application layer and re- quires more deeply intrusions into the operating system. We argue that the integration is feasible and that it yields a sim- ulation tool, which can perform similar to other tools like TOSSIM or COOJA but benets notably from the exibility of OMNeT++ and its cornucopia of readily available models provided by the community.
    Preview · Conference Paper · Jan 2009
  • Stephan Mank · Reinhardt Karnapke · Jörg Nolte
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    ABSTRACT: Today, wireless sensor networks are typically realized using cheap radio transceivers offering low bandwidth communication only. When physical events in the real world trigger spontaneous communication in many nodes, the single communication channel is under heavy load and many messages are lost due to collisions. CSMA/CA schemes are well suited to spontaneous communication, but do not provide a high channel utilization under heavy load. TDMAprotocols have some conceptual advantage here, but in the case of mobile sensor nodes they need to be adaptive and establish TDMAschedules on demand. In this paper we introduce the MLMAC (mobile LMAC) protocol. MLMAC is a novel TDMA based MAC protocol that can react on changing radio neighborhoods in mobile networks. In addition to the conceptual description of MLMAC, we also present the results of real experiments with a group of mobile sensor nodes based on RCX robots.
    No preview · Article · Jan 2009 · Ad Hoc & Sensor Wireless Networks
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    ABSTRACT: Today, even small residential buildings have a number of complex electrical devices that advocate the usage of automated control systems. But currently available systems are either hard to handle or expensive. This paper describes an automated house control system that has been in use for the last 4 years. It has been built using only freely available, inexpensive hardware and the open source operating system REFLEX.
    Preview · Conference Paper · Oct 2008
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    Andreas Lagemann · Jörg Nolte
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    ABSTRACT: Simulation normally serves one of two purposes. The rst one is evaluation of certain algorithms. The second one is development and test of applications with infrastructural requirements which exceed those commonly available (e.g. distributed applications for wireless networks). In the latter case it is highly desirable that the code used for simulation can be easily adopted to real hardware with minor modi- cations. The .NET framework is { like Java { platform independent insofar as it only depends on a virtual machine implementation for each device it is meant to run on. There- fore for some application elds it is attractive to be able to write plain C# code which can then be run with a simulator like OMNeT++. This paper introduces CsharpSimpleModule, an extension to OMNeT++, which { like its companion JSimpleModule does for Java { allows you to write OMNeT++ simula- tion modules in C# and mix them freely with plain OM- NeT++ modules, thus allowing you to build upon existing OMNeT++ frameworks (e.g INET or MobilityFramework). Besides giving a short introduction to the usage of Csharp- SimpleModule its general architecture will be illustrated and selected implementation issues will be discussed.
    Preview · Conference Paper · Jan 2008
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    Stephan Mank · Reinhardt Karnapke · Joerg Nolte
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    ABSTRACT: typically cheap devices offering low bandwidth communication only. When physical events in the real world trigger spontaneous communication in many nodes the single communication channel is under heavy load and many messages are lost due to collisions. CSMA/CA schemes are well suited to spontaneous communica- tion, but do not provide a high channel utilization under heavy load. TDMA protocols have some conceptual advantage here, but in the case of mobile sensor nodes they need to be adaptive and establish TDMA schedules on demand. MLMAC is a novel TDMA based MAC protocol that can react on changing radio neighborhoods in mobile networks. In this paper we introduce the MLMAC protocol and present the results of real experiments with a group of mobile sensor nodes based on RCX robots.
    Preview · Conference Paper · Nov 2007
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    M. Kruger · R. Karnapke · J. Nolte
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    ABSTRACT: COCOS (coordinated communicating sensors) is a lean middleware platform for wireless sensor networks. The major programming abstractions of Cocos are distributed sensor spaces. All objects in such a space can be collectively addressed. This way, high-level data-parallel programming concepts such as global reductions are possible. This paper introduces the spaces of Cocos and describes their usage.
    Preview · Conference Paper · Oct 2007
  • Karsten Walther · René Herzog · Jörg Nolte
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    ABSTRACT: Most embedded control systems react on events in the real world by reading sensors and controlling actuators in real-time. This general behavior can be directly mapped onto event-driven systems in a natural and straightforward manner for a large variety of applications. Further real-time analysis and profiling on the same level of abstraction is possible for event-driven systems. This significantly helps developers of deeply embedded real-time applications. In this paper we introduce simulative profiling concepts and static analysis basics for the real-time analysis of event-driven systems. Furthermore we present a prototype analysis tool for the REFLEX operating system that integrates real-time analysis into the software development cycle.
    No preview · Conference Paper · Jul 2007