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Selbststabilisierende Systeme

Kontakt Prof. Dr. rer. nat. Volker Turau
Mitarbeiter Christoph Weyer

Projektbeschreibung

Ein verteiltes System ist selbststabilisierend, wenn es aus jedem beliebigen Zustand nach endlich vielen Schritten in einen legitimen Zustand findet und das System bis zum Auftritt eines Fehlers in einem legitimen Zustand bleibt. Selbststabiliersung stellt damit eine Technik zur nicht-maskierenden Fehlertoleranz dar. In diesem Institut untersuchen wir selbststablisierende Algorithmen unter den Gesichtspunkten Effizienz, Verhalten im Fehlerfall und forschen an Werkzeugen zur Unterstützung der Entwicklung solcher Algorithmen.

Teilprojekte

Publikationen

Volker Turau. Computing the Fault-Containment-Time of Self-Stabilizing Algorithms using Markov Chains and Lumping. In Stabilization, Safety, and Security of Distributed Systems - 19th International Symposium(SSS 2017), November 2017, pp. 62–77. Boston, USA.
[BibTeX] [Abstract] [DOI] [Folien]
@InProceedings{Telematik_SSS_2017, author = {Volker Turau}, title = {Computing the Fault-Containment-Time of Self-Stabilizing Algorithms using Markov Chains and Lumping}, booktitle = {Stabilization, Safety, and Security of Distributed Systems - 19th International Symposium(SSS 2017)}, pages = {62-77}, day = {5-8}, month = nov, year = 2017, location = {Boston, USA}, }
Abstract: The analysis of self-stabilizing algorithms is in the vast majority of all cases limited to the worst case stabilization time starting from an arbitrary configuration. Considering the fact that these algorithms are intended to provide fault tolerance in the long run this is not the most relevant metric. From a practical point of view the worst case time to recover in case of a single fault is much more crucial. This paper presents techniques to derive upper bounds for the mean time to recover from a single fault for self-stabilizing algorithms Markov chains in combination with lumping. To illustrate the applicability of the techniques they are applied to a self-stabilizing coloring algorithm.
Volker Turau und Gerry Siegemund. Scalable Routing for Topic-based Publish/Subscribe Systems under Fluctuations. In Proceedings of International Conference on Distributed Computing Systems - ICDCS 2017, Juni 2017, pp. 1608–1617. Atlanta, USA.
[BibTeX] [Abstract] [DOI] [Folien]
@InProceedings{Telematik_ICDS_2017, author = {Volker Turau and Gerry Siegemund}, title = {Scalable Routing for Topic-based Publish/Subscribe Systems under Fluctuations}, booktitle = {Proceedings of International Conference on Distributed Computing Systems - ICDCS 2017}, pages = {1608-1617}, day = {5-8}, month = jun, year = 2017, location = {Atlanta, USA}, }
Abstract: The loose coupling and the inherent scalability make publish/subscribe systems an ideal candidate for event-driven services for wireless networks using low power protocols such as IEEE 802.15.4. This work introduces a distributed algorithm to build and maintain a routing structure for such networks.The algorithm dynamically maintains a multicast tree for each node. While previous work focused on minimizing these trees we aim to keep the effort to maintain them in case of fluctuations of subscribers low. The multicast trees are implicitly defined by a novel structure called augmented virtual ring. The main contribution is a distributed algorithm to build and maintain this augmented virtual ring. Maintenance operations after sub-and unsubscriptions require message exchange in a limited region only. We compare the average lengths of the constructed forwarding paths with an almost ideal approach. As a result of independent interest we present a distributed algorithm using messages of size O(logn) for constructing virtual rings of graphs that are on average shorter than rings based on depth first search.
Gerry Siegemund und Volker Turau. PSVR - Self-Stabilizing Publish/Subscribe Communication for Ad-Hoc Networks (Short Paper). In Proceedings of Stabilization, Safety, and Security of Distributed Systems - 18th International Symposium, November 2016, pp. 346–351. Lyon, France.
[BibTeX] [Abstract] [DOI] [Folien]
@InProceedings{Telematik_SSS_2016, author = {Gerry Siegemund and Volker Turau}, title = {PSVR - Self-Stabilizing Publish/Subscribe Communication for Ad-Hoc Networks (Short Paper)}, booktitle = {Proceedings of Stabilization, Safety, and Security of Distributed Systems - 18th International Symposium}, pages = {346-351}, day = {7-10}, month = nov, year = 2016, location = {Lyon, France}, }
Abstract: PSVR is a novel routing algorithm for pub/sub systems in ad-hoc networks focusing on scenarios where communications links are unstable and nodes frequently change subscriptions. It is a compromise of size and maintenance effort for routing tables due to sub- and unsubscriptions and the length of routing paths. Designed in a self-stabilizing manner it scales well with network size. The evaluation with real world deployment reveals that PSVR only needs slightly more messages than a close to optimal routing structure for publication delivery, and creates shorter routing paths than an existing self-stabilizing algorithm.
Stefan Lohs, Jörg Nolte, Gerry Siegemund und Volker Turau. Influence of Topology-Fluctuations on Self-Stabilizing Algorithms. In 2016 International Conference on Distributed Computing in Sensor Systems DCOSS 2016 Poster Abstract, Mai 2016, pp. 122–124. Washington, DC, USA.
[BibTeX] [Abstract] [DOI]
@InProceedings{DCOSS_POSTER_2016, author = {Stefan Lohs and J{\"o}rg Nolte and Gerry Siegemund and Volker Turau}, title = {Influence of Topology-Fluctuations on Self-Stabilizing Algorithms}, booktitle = {2016 International Conference on Distributed Computing in Sensor Systems DCOSS 2016 Poster Abstract}, pages = {122-124}, day = {26-28}, month = may, year = 2016, location = {Washington, DC, USA}, }
Abstract: Self-stabilizing systems have in theory the unique and provable ability, to always return to a valid system state even in the face of failures. These properties are certainly desirable for domains like wireless ad-hoc networks with numerous unpredictable faults. Unfortunately, the time in which the system returns to a valid state is not predictable and potentially unbound. The failure rate typically depends on physical phenomena and in self-stabilizing systems each node tries to react to failures in an inherently adaptive fashion by the cyclic observation of the states of its neighbors. When state changes are either too quick or too slow the system might never reach a state that is sufficiently stable for a specific task. In this paper, we investigate the influences of the error rate on the (stability) convergence time on the basis of topology information acquired in real network experiments. This allows us to asses the asymptotic behavior of relevant self-stabilizing algorithms in typical wireless networks.
Sandra Beyer, Stefan Lohs, Jörg Nolte, Reinhardt Karnapke und Gerry Siegemund. Self-Stabilizing Structures for Data Gathering in Wireless Sensor Networks. In Proceedings of the International Conference on Sensor Technologies and Applications (Sensorcomm), August 2015, pp. 1–8. Venice, Italy.
[BibTeX] [Abstract]
@InProceedings{Cottbus_Sensorcomm_2015, author = {Sandra Beyer and Stefan Lohs and J{\"o}rg Nolte and Reinhardt Karnapke and Gerry Siegemund}, title = {Self-Stabilizing Structures for Data Gathering in Wireless Sensor Networks}, booktitle = {Proceedings of the International Conference on Sensor Technologies and Applications (Sensorcomm)}, pages = {1-8}, month = aug, year = 2015, location = {Venice, Italy}, }
Abstract: Wireless Sensor Networks (WSN) enable a number of applications, with monitoring of habitats, office buildings, or restricted areas most prominent among them. All of these applications have one thing in common: the need to commu- nicate. However, the nature of the wireless medium results in quite a few problems. Lossy communication links with transient faults require acknowledgments, retransmissions, and route re- pair mechanisms. Tree- or similar structures for data gathering scenarios lead to increased load closer to the sink, with congestion, higher buffer space requirements, and energy drain as results. The second problem is often addressed by aggregation and reduction schemes. These schemes are bound to fail, however, when the underlying structure is compromised due to changes in the connectivity between nodes. Therefore, it is necessary to focus on the structures first of all. We address the problem of transient faults by using the inherent fault tolerance of self- stabilizing algorithms when building and using tree- or tiers (communication-) structures. In this paper we show that self- stabilizing structures are suitable for data gathering scenarios in WSN by comparison of the connectivity achieved by our self- stabilizing tiers algorithm and the tree algorithm from Dolev with that of Collection Tree Protocol (CTP), the standard data- gathering protocol for TinyOS.
Gerry Siegemund, Volker Turau und Christoph Weyer. A Dynamic Topology Control Algorithm for Wireless Sensor Networks. In Proceedings of the International Conference on Ad-hoc, Mobile and Wireless Networks, ADHOC-NOW 2015, Juni 2015, pp. 3–18. Athens, Greece.
[BibTeX] [Abstract] [DOI] [Folien]
@InProceedings{Telematik_Adhoc-Now_2015, author = {Gerry Siegemund and Volker Turau and Christoph Weyer}, title = {A Dynamic Topology Control Algorithm for Wireless Sensor Networks}, booktitle = {Proceedings of the International Conference on Ad-hoc, Mobile and Wireless Networks, ADHOC-NOW 2015}, pages = {3-18}, month = jun, year = 2015, location = {Athens, Greece}, }
Abstract: Topology control algorithms (TCAs) are used in wireless sensor networks to reduce interference by carefully choosing communication links. Since the quality of the wireless channel is subject to fluctuations over time TCAs must repeatedly recompute the topology. TCAs ensure quick adjustment to new or deteriorating links while preventing precipitant changes due to transient faults. This paper contributes a novel dynamic TCA that provides a compromise between agility and stability, and constructs connected topologies for low latency routing. Furthermore, it enforces memory restrictions and is of high practical relevance for real sensor network hardware.
Gerry Siegemund, Volker Turau und Khaled Maâmra. A Self-stabilizing Publish/Subscribe Middleware for Wireless Sensor Networks. In Proceedings of the International Conference on Networked Systems (NetSys), März 2015, pp. 1–8. Cottbus, Germany.
[BibTeX] [Abstract] [DOI] [Folien]
@InProceedings{Telematik_NetSys_2015, author = {Gerry Siegemund and Volker Turau and Khaled Maâmra}, title = {A Self-stabilizing Publish/Subscribe Middleware for Wireless Sensor Networks}, booktitle = {Proceedings of the International Conference on Networked Systems (NetSys)}, pages = {1-8}, month = mar, year = 2015, location = {Cottbus, Germany}, }
Abstract: This paper presents a scalable, self-stabilizing middleware for channel-based publish/subscribe systems for wireless sensor networks. The middleware eventually provides safety and liveness properties such as the guaranteed delivery of all published messages to all subscribers of the corresponding channel and the correct handling of subscriptions and unsubscriptions, while no error occurs. We consider transient message and memory corruptions and also respect dynamic network changes such as node and link removals and additions. We assume the message passing model and guarantee delivery of publications to new subscribers after O(n) steps.
Brahim Negazzi, Volker Turau, Mohammed Haddad und Hamamache Kheddouci. A Self-Stabilizing Algorithm for Edge Monitoring Problem. In Proceedings of the 16th International Symposium on Stabilization, Safety, and Security of Distributed Systems (SSS'14), September 2014, pp. 93–105. Paderborn, Germany.
[BibTeX] [Abstract] [DOI] [Folien]
@InProceedings{Telematik_SSS_2014_Edge_Monitoring_Problem, author = {Brahim Negazzi and Volker Turau and Mohammed Haddad and Hamamache Kheddouci}, title = {A Self-Stabilizing Algorithm for Edge Monitoring Problem}, booktitle = {Proceedings of the 16th International Symposium on Stabilization, Safety, and Security of Distributed Systems (SSS'14)}, pages = {93-105}, day = {28-30}, month = sep, year = 2014, location = {Paderborn, Germany}, }
Abstract: Self-monitoring is a simple and effective mechanism for the security of wireless sensor networks(WSNs), especially to cope against compromised nodes. A node v can monitor an edge e if both end-nodes of e are neighbors of v: i.e., e together with v forms a triangle in the graph. Moreover, some edges need more than one monitor. Finding a set of monitoring nodes satisfying all monitoring constraints is called the edge-monitoring problem. The minimum edge-monitoring problem is long known to be NP-complete. In this paper, we present a novel silent self-stabilizing algorithm for computing a minimal edge-monitoring set. Correctness and termination are proven for the unfair distributed daemon.
Gerry Siegemund, Volker Turau und Khaled Maâmra. Brief Announcement: Publish/Subscribe on Virtual Rings. In Proceedings of the 16th International Symposium on Stabilization, Safety, and Security of Distributed Systems (SSS'14), September 2014, pp. 343–345. Paderborn, Germany.
[BibTeX] [Abstract]
@InProceedings{Telematik_SSS_2014_Virtual_Ring, author = {Gerry Siegemund and Volker Turau and Khaled Maâmra}, title = {Brief Announcement: Publish/Subscribe on Virtual Rings}, booktitle = {Proceedings of the 16th International Symposium on Stabilization, Safety, and Security of Distributed Systems (SSS'14)}, pages = {343-345}, day = {28-30}, month = sep, year = 2014, location = {Paderborn, Germany}, }
Abstract: This paper introduces a scalable, self-stabilizing, channel-based publish/subscribe system for wireless sensor networks. As base structure a virtual ring is maintained. We consider message and memory corruptions and also respect dynamic network changes, such as, node and link removals and additions.
Gerry Siegemund, Volker Turau, Christoph Weyer, Stefan Lobs und Jörg Nolte. Brief Announcement: Agile and Stable Neighborhood Protocol for WSNs. In Proceedings of the 15th International Symposium on Stabilization, Safety, and Security of Distributed Systems (SSS'13), November 2013, pp. 376–378. Osaka, Japan.
[BibTeX] [Abstract] [DOI]
@InProceedings{Telematik_SSS_2013_Neighborhood, author = {Gerry Siegemund and Volker Turau and Christoph Weyer and Stefan Lobs and J{\"o}rg Nolte}, title = {Brief Announcement: Agile and Stable Neighborhood Protocol for WSNs}, booktitle = {Proceedings of the 15th International Symposium on Stabilization, Safety, and Security of Distributed Systems (SSS'13)}, pages = {376-378}, day = {13-16}, month = nov, year = 2013, location = {Osaka, Japan}, }
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 neighbourhood management protocol (NMP) providing a neighbourhood relation sufficiently stable to apply existing SSAs in WSNs.
Brahim Negazzi, Volker Turau, Mohammed Haddad und Hamamache Kheddouci. A Self-Stabilizing Algorithm for Maximal p-Star Decomposition of General Graphs. In Proceedings of the 15th International Symposium on Stabilization, Safety, and Security of Distributed Systems (SSS'13), November 2013, pp. 74–85. Osaka, Japan.
[BibTeX] [Abstract] [DOI]
@InProceedings{Telematik_SSS_2013_MaxPStar, author = {Brahim Negazzi and Volker Turau and Mohammed Haddad and Hamamache Kheddouci}, title = {A Self-Stabilizing Algorithm for Maximal p-Star Decomposition of General Graphs}, booktitle = {Proceedings of the 15th International Symposium on Stabilization, Safety, and Security of Distributed Systems (SSS'13)}, pages = {74-85}, day = {13-16}, month = nov, year = 2013, location = {Osaka, Japan}, }
Abstract: A p-star is a complete bipartite graph K{1,p} with one center node and p leaf nodes. In this paper we propose the first distributed self-stabilizing algorithm for graph decomposition into p-stars. For a graph G and an integer p>=1, this decomposition provides disjoint components of G where each component forms a p-star. We prove convergence and correctness of the algorithm under an unfair distributed daemon. The stabilization time is 2*floor(n/p+1)+2 rounds.
Gerry Siegemund, Volker Turau, Stefan Lohs und Jörg Nolte. Directed Link Utilization with Mahalle+. In Proceedings of the 12th GI/ITG KuVS Fachgespräch "Drahtlose Sensornetze" (FGSN'13), September 2013. Cottbus, Germany.
[BibTeX] [Abstract] [PDF]
@InProceedings{Telematik_STLN_2013_DirectedLinkUtil, author = {Gerry Siegemund and Volker Turau and Stefan Lohs and J{\"o}rg Nolte}, title = {Directed Link Utilization with Mahalle+}, booktitle = {Proceedings of the 12th GI/ITG KuVS Fachgespr{\"a}ch "Drahtlose Sensornetze" (FGSN'13)}, day = {12-13}, month = sep, year = 2013, location = {Cottbus, Germany}, }
Abstract: Self-stabilization provides non-masking fault toler- ance in distributed systems. 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. Therefore, neighborhood management protocols (NMP) are used to ensure the stability of the network topology for a longer time period. Furthermore, symmetrical links between nodes are more desirable than unsymmetrical ones, therefore, unidirectional links are often omitted. This paper presents an augmentation of the NMP Mahalle+to transparently utilize certain unidirectional links to increase the performance of SSAs running on top of Mahalle+.
Gerry Siegemund und Stefan Lohs. GlueAPI - Joining REFLEX and CometOS. Technical Report urn:nbn:de:gbv:830-tubdok-12285, Hamburg University of Technology, Hamburg, Germany, 2013.
[BibTeX] [Abstract] [PDF]
@TechReport{Telematik_Siegemund_2013_GlueAPI, author = {Gerry Siegemund and Stefan Lohs}, title = {GlueAPI - Joining REFLEX and CometOS}, number = {urn:nbn:de:gbv:830-tubdok-12285}, institution = {Hamburg University of Technology}, address = {Hamburg, Germany}, year = 2013, }
Abstract: Wireless sensor networks (WSN) are build for various tasks in arbitrary environments. Operating systems for sensor nodes, the components of WSNs, appear in multiple forms, from a variety of vendors, universities, or private persons. The GlueAPI is a merge layer to combine the usability of two such operating systems: REFLEX of the Brandenburg University of Technology and CometOS of the Hamburg University of Technology. Both operating systems are suitable for simulations using the OMNeT++ framework and several hardware platforms.
Sven Köhler, Volker Turau und Gerhard Mentges. Self-stabilizing local k-placement of replicas with minimal variance. In Proceedings of the 14th International Symposium on Stabilization, Safety, and Security of Distributed Systems (SSS'12), Springer, Oktober 2012, pp. 16–30. Toronto, Canada.
[BibTeX] [Abstract] [DOI]
@InProceedings{Telematik_KT_SSS12, author = {Sven K{\"o}hler and Volker Turau and Gerhard Mentges}, title = {Self-stabilizing local k-placement of replicas with minimal variance}, booktitle = {Proceedings of the 14th International Symposium on Stabilization, Safety, and Security of Distributed Systems (SSS'12)}, pages = {16-30}, series = {Lecture Notes in Computer Science}, volume = {7596}, publisher = {Springer}, day = {1-4}, month = oct, year = 2012, location = {Toronto, Canada}, }
Abstract: Large scale distributed systems require replication of resources to amplify availability and to provide fault tolerance. The placement of replicated resources significantly impacts performance. This paper considers local k-placements: Each node of a network has to place k replicas of a resource among its direct neighbors. The load of a node in a given local k-placement is the number of replicas it stores. The local k-placement problem is to achieve a preferably homogeneous distribution of the loads. We present a novel self-stabilizing, distributed, asynchronous, scalable algorithm for the k-placement problem such that the standard deviation of the distribution of the loads assumes a local minimum.
Stefan Lohs, Gerry Siegemund, Jörg Nolte und Volker Turau. Mission Statement: ToleranceZone A Self-Stabilizing Middleware for Wireless Sensor Netzworks. In Proceedings of the 11th GI/ITG KuVS Fachgespräch "Drahtlose Sensornetze" (FGSN'12), September 2012. Darmstadt, Germany.
[BibTeX] [Abstract] [PDF]
@InProceedings{Telematik_LSNT_2012_TZone_Mission, author = {Stefan Lohs and Gerry Siegemund and J{\"o}rg Nolte and Volker Turau}, title = {Mission Statement: ToleranceZone A Self-Stabilizing Middleware for Wireless Sensor Netzworks}, booktitle = {Proceedings of the 11th GI/ITG KuVS Fachgespr{\"a}ch "Drahtlose Sensornetze" (FGSN'12)}, day = {13-14}, month = sep, year = 2012, location = {Darmstadt, Germany}, }
Abstract: Wireless sensor networks (WSN) can be used in a wide range of monitoring and controlling applications. These networks consist of nodes with sparse resources, which makes application implementation challenging. Therefore, many mid- dleware systems were developed in the last decade. Furthermore, unattended and long-living deployments of WSNs need fault-tolerant software architectures. The goal of the TOLERANCEZONE project is to design a self-stabilizing middleware, which supports the development of autonomously recovering and highly fault-tolerant WSN applications.
Sven Köhler und Volker Turau. Fault-containing self-stabilization in asynchronous systems with constant fault-gap. Distributed Computing, 25(3):207–224, 2012.
[BibTeX] [Abstract] [DOI]
@Article{Telematik_KT_2011_DC, author = {Sven K{\"o}hler and Volker Turau}, title = {Fault-containing self-stabilization in asynchronous systems with constant fault-gap}, pages = {207-224}, journal = {Distributed Computing}, volume = {25}, number = {3}, year = 2012, issn = {0178-2770}, }
Abstract: This paper presents a new transformation which adds fault-containment properties to silent self-stabilizing algorithms. The transformation features a constant slow-down factor and the fault-gap—that is the minimal time between two containable faults—is also constant. The transformation scales well to arbitrarily large systems and avoids global synchronization. The presented transformation is the first with a constant fault-gap and requires no knowledge of the system size.
Sven Köhler und Volker Turau. Space-efficient fault-containment in dynamic networks. In Proceedings of the 13th International Symposium on Stabilization, Safety, and Security of Distributed Systems (SSS'11), Springer, Oktober 2011, pp. 311–325. Grenoble, France.
[BibTeX] [Abstract] [DOI]
@InProceedings{Telematik_KT_SSS11, author = {Sven K{\"o}hler and Volker Turau}, title = {Space-efficient fault-containment in dynamic networks}, booktitle = {Proceedings of the 13th International Symposium on Stabilization, Safety, and Security of Distributed Systems (SSS'11)}, pages = {311-325}, series = {Lecture Notes in Computer Science}, volume = {6976}, publisher = {Springer}, day = {10-12}, month = oct, year = 2011, location = {Grenoble, France}, }
Abstract: Bounding the impact of transient small-scale faults by self-stabilizing protocols has been pursued with independent objectives: Optimizing the system's reaction upon topological changes (e.g. super-stabilization), and reducing system recovery time from memory corruptions (e.g. fault-containment). Even though transformations adding either super-stabilization or fault-containment to existing protocols exists, none of them preserves the other. This paper makes a first attempt to combine both objectives. We provide a transformation adding fault-containment to silent self-stabilizing protocols while simultaneously preserving the property of self-stabilization and the protocol's behavior in face of topological changes. In particular, the protocol's response to a topology change remains unchanged even if a memory corruption occurs in parallel to the topology change. The presented transformation increases the memory footprint only by a factor of 4 and adds O(1) bits per edge. All previously known transformations for fault-containing self-stabilization increase the memory footprint by a factor of 2m/n.
Volker Turau und Bernd Hauck. A new Analysis of a Self-Stabilizing Maximum Weight Matching Algorithm with Approximation Ratio 2. Theoretical Computer Science, 412(40):5527–5540, September 2011. Stabilization, Safety and Security.
[BibTeX] [Abstract] [DOI]
@Article{Telematik_HT_2010_TCS_Matching, author = {Volker Turau and Bernd Hauck}, title = {A new Analysis of a Self-Stabilizing Maximum Weight Matching Algorithm with Approximation Ratio 2}, pages = {5527-5540}, journal = {Theoretical Computer Science}, volume = {412}, number = {40}, month = sep, year = 2011, keywords = {Self-stabilizing algorithms, approximation algorithm, weighted matching, distributed algorithms}, issn = {0304-3975}, note = {Stabilization, Safety and Security}, }
Abstract: The maximum weight matching problem is a fundamental problem in graph theory with a variety of important applications. Recently Manne and Mjelde presented the first self-stabilizing algorithm computing a 2-approximation of the optimal solution. They established that their algorithm stabilizes after O(2^n) (resp. O(3^n)) moves under a central (resp. distributed) scheduler. This paper contributes a new analysis improving these bounds considerably. In particular it is shown that the algorithm stabilizes after O(nm) moves under the central scheduler and that a modified version of the algorithm also stabilizes after O(nm) moves under the distributed scheduler. The paper presents a new proof technique based on graph reduction to analyze the complexity of self-stabilizing algorithms.
Volker Turau und Bernd Hauck. A fault-containing self-stabilizing (3 - 2/(Delta+1))-approximation algorithm for vertex cover in anonymous networks. Theoretical Computer Science, 412(33):4361–4371, 2011.
[BibTeX] [Abstract] [DOI]
@Article{Telematik_HT_2011_TCSVC, author = {Volker Turau and Bernd Hauck}, title = {A fault-containing self-stabilizing (3 - 2/(Delta+1))-approximation algorithm for vertex cover in anonymous networks}, pages = {4361-4371}, journal = {Theoretical Computer Science}, volume = {412}, number = {33}, year = 2011, keywords = {Self-stabilizing algorithms, Fault tolerance, Distributed algorithms, Graph algorithms}, }
Abstract: The non-computability of many distributed tasks in anonymous networks is well known. This paper presents a deterministic self-stabilizing algorithm to compute a 3 - (2 / (Delta+1))-approximation of a minimum vertex cover in anonymous networks. The algorithm operates under the distributed unfair scheduler, stabilizes after O(n+m) moves respectively O(Delta) rounds, and requires O(log n) storage per node. Recovery from a single fault is reached within a constant time and the contamination number is O(Delta). For trees the algorithm computes a 2-approximation of a minimum vertex cover.
Sven Köhler und Volker Turau. A new Technique for proving Self-Stabilization under the Distributed Scheduler. In Proceedings of the 12th International Symposium on Stabilization, Safety, and Security of Distributed Systems (SSS'10), Springer, September 2010, pp. 65–79. New York, NY, USA.
[BibTeX] [Abstract] [DOI] [PDF]
@InProceedings{Telematik_KT_ProofTechnique, author = {Sven K{\"o}hler and Volker Turau}, title = {A new Technique for proving Self-Stabilization under the Distributed Scheduler}, booktitle = {Proceedings of the 12th International Symposium on Stabilization, Safety, and Security of Distributed Systems (SSS'10)}, pages = {65-79}, series = {Lecture Notes in Computer Science}, volume = {6366}, publisher = {Springer}, day = {20-22}, month = sep, year = 2010, location = {New York, NY, USA}, }
Abstract: Proving stabilization of a complex algorithm under the distributed scheduler is a non-trivial task. This paper introduces a new method which allows to extend proofs for the central scheduler to the distributed scheduler. The practicability of the method is shown by applying it to two existing algorithms, for which stabilization under the distributed scheduler was an open problem.
Sven Köhler und Volker Turau. Fault-containing self-stabilization in asynchronous systems with constant fault-gap. In Proceedings of the 30th IEEE International Conference on Distributed Computing Systems (ICDCS'10), IEEE Computer Society, Juni 2010, pp. 418–427. Genoa, Italy.
[BibTeX] [Abstract] [DOI] [PDF]
@InProceedings{Telematik_KT_FaultContain, author = {Sven K{\"o}hler and Volker Turau}, title = {Fault-containing self-stabilization in asynchronous systems with constant fault-gap}, booktitle = {Proceedings of the 30th IEEE International Conference on Distributed Computing Systems (ICDCS'10)}, pages = {418-427}, publisher = {IEEE Computer Society}, day = {21-25}, month = jun, year = 2010, location = {Genoa, Italy}, }
Abstract: This paper presents a new transformation which adds fault-containment properties to any silent self-stabilizing protocol. The transformation features a constant slow-down factor and the fault-gap – that is the minimal time between two containable faults – is constant. The transformation scales well to arbitrarily large systems and avoids global synchronization.
Volker Turau. Self-Stabilizing Vertex Cover in Anonymous Networks with Optimal Approximation Ratio. Parallel Processing Letters, 20(2):173–186, 2010.
[BibTeX] [Abstract] [DOI]
@Article{Telematik_T_2010_PPL, author = {Volker Turau}, title = {Self-Stabilizing Vertex Cover in Anonymous Networks with Optimal Approximation Ratio}, pages = {173-186}, journal = {Parallel Processing Letters}, volume = {20}, number = {2}, year = 2010, }
Abstract: This paper presents a deterministic self-stabilizing algorithm that approximates a minimum vertex cover in anonymous networks with ratio 2 using the distributed scheduler and the link-register model with composite atomicity. No algorithm with a better approximation ratio can exist. The algorithm stabilizes in O(min{n, Δ², Δ log3 n}) rounds and requires O(Δ) memory per node.
Volker Turau und Bernd Hauck. A Self-Stabilizing Approximation Algorithm for Vertex Cover in Anonymous Networks. In Proceedings of the 11th International Symposium on Stabilization, Safety, and Security of Distributed Systems (SSS'09), Springer, November 2009, pp. 341–353. Lyon, France.
[BibTeX] [Abstract] [DOI]
@InProceedings{Telematik_HT_2009_VC, author = {Volker Turau and Bernd Hauck}, title = {A Self-Stabilizing Approximation Algorithm for Vertex Cover in Anonymous Networks}, booktitle = {Proceedings of the 11th International Symposium on Stabilization, Safety, and Security of Distributed Systems (SSS'09)}, pages = {341-353}, series = {Lecture Notes in Computer Science}, volume = {5873}, publisher = {Springer}, day = {3-6}, month = nov, year = 2009, location = {Lyon, France}, }
Abstract: This paper presents a deterministic self-stabilizing algorithm that computes a 3-approximation vertex cover in anonymous networks. It reaches a legal state after O(n+m) moves or 2n + 1 rounds respectively and recovers from a single fault within a constant containment time. The contamination number is 2 Delta + 1. An enhanced version of this algorithm achieves a 2-approximation on trees.
Andreas Lagemann, Jörg Nolte, Christoph Weyer und Volker Turau. Mission Statement: Applying Self-Stabilization to Wireless Sensor Networks. In Proceedings of the 8th GI/ITG KuVS Fachgespräch "Drahtlose Sensornetze" (FGSN'09), August 2009, pp. 47–49. Hamburg, Germany.
[BibTeX] [Abstract] [PDF]
@InProceedings{Telematik_LNWT_2009_SelfWISE, author = {Andreas Lagemann and J{\"o}rg Nolte and Christoph Weyer and Volker Turau}, title = {Mission Statement: Applying Self-Stabilization to Wireless Sensor Networks}, booktitle = {Proceedings of the 8th GI/ITG KuVS Fachgespr{\"a}ch "Drahtlose Sensornetze" (FGSN'09)}, pages = {47-49}, day = {13-14}, month = aug, year = 2009, location = {Hamburg, Germany}, }
Abstract: Long living and unattended deployments of wireless sensor networks requires fault-tolerant solutions. Self-stabilizing algorithms are providing these properties in an elegant and verifiable way. Recently, a lot of research has been performed to determine appropriate means to apply these promising technique to wireless sensor networks. In this paper the current state of the art in this field is given. Additionally, three major challenges are presented for achieving self-stabilizing sensor networks.
Christoph Weyer, Volker Turau, Andreas Lagemann und Jörg Nolte. Programming Wireless Sensor Networks in a Self-Stabilizing Style. In Proceedings of the Third International Conference on Sensor Technologies and Applications (SENSORCOMM'09), Juni 2009. Athens, Greece.
[BibTeX] [Abstract] [Folien]
@InProceedings{Telematik_WLT_2009_SelfWISE, author = {Christoph Weyer and Volker Turau and Andreas Lagemann and J{\"o}rg Nolte}, title = {Programming Wireless Sensor Networks in a Self-Stabilizing Style}, booktitle = {Proceedings of the Third International Conference on Sensor Technologies and Applications (SENSORCOMM'09)}, day = {18-23}, month = jun, year = 2009, location = {Athens, Greece}, }
Abstract: Wireless Sensor Networks (WSNs) operate in an unstable environment 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 WSNs. The analysis is accomplished with SelfWISE, a framework providing programming abstractions for selfstabilizing algorithms. The performed analysis considers the target models as well as network size and density. This demonstrates the usability of SelfWISE for evaluating selfstabilizing algorithms under a wide range of models.
Christoph Weyer und Volker Turau. SelfWISE: A Framework for Developing Self-Stabilizing Algorithms. In Proceedings of the 16th ITG/GI - Fachtagung Kommunikation in Verteilten Systemen (KiVS'09), März 2009, pp. 67–78. Kassel, Germany.
[BibTeX] [Abstract] [Folien]
@InProceedings{Telematik_TW_2009_SelfWISE, author = {Christoph Weyer and Volker Turau}, title = {SelfWISE: A Framework for Developing Self-Stabilizing Algorithms}, booktitle = {Proceedings of the 16th ITG/GI - Fachtagung Kommunikation in Verteilten Systemen (KiVS'09)}, pages = {67-78}, day = {2-6}, month = mar, year = 2009, location = {Kassel, Germany}, }
Abstract: This paper introduces SelfWISE, a framework for enabling wireless sensor networks to be programmed in a self-stabilizing manner. The framework eases the formal specification of algorithms by abstracting from low-level details such as wireless channel and hardwarespecific characteristics. SelfWISE consists of a language for expressing self-stabilizing algorithms, a runtime environment for simulating algorithms in wireless sensor networks, and supporting tools. The hereby applied transformation of formally described algorithms into the simulation environment preserves the self-stabilizing properties. Development, evaluation, and debugging of self-stabilizing algorithms is considerably facilitated by utilizing SelfWISE.
Volker Turau und Bernd Hauck. A Self-Stabilizing Algorithm for Constructing Weakly Connected Minimal Dominating Sets. Information Processing Letters, 109(14):763–767, 2009.
[BibTeX] [Abstract] [DOI]
@Article{Telematik_HT_2009_WCMDS, author = {Volker Turau and Bernd Hauck}, title = {A Self-Stabilizing Algorithm for Constructing Weakly Connected Minimal Dominating Sets}, pages = {763-767}, journal = {Information Processing Letters}, volume = {109}, number = {14}, year = 2009, keywords = {Self-stabilizing algorithms, Fault tolerance, Distributed algorithms, Graph algorithms}, issn = {0020-0190}, }
Abstract: This paper presents a new distributed self-stabilizing algorithm for the weakly connected minimal dominating set problem. It assumes a self-stabilizing algorithm to compute a breadth-first tree. Using an unfair distributed scheduler the algorithm stabilizes in at most O(nmA) moves, where A is the number of moves to construct a breadth-first tree. All previously known algorithms required an exponential number of moves.
Volker Turau und Christoph Weyer. Fault Tolerance in Wireless Sensor Networks through Self-Stabilization. International Journal of Communication Networks and Distributed Systems, 2(1):78–98, 2009.
[BibTeX] [Abstract] [DOI]
@Article{Telematik_TW_2009_SelfStabilization, author = {Volker Turau and Christoph Weyer}, title = {Fault Tolerance in Wireless Sensor Networks through Self-Stabilization}, pages = {78-98}, journal = {International Journal of Communication Networks and Distributed Systems}, volume = {2}, number = {1}, year = 2009, }
Abstract: Wireless sensor networks (WSNs) suffer from resource limitations, high failure rates and faults caused by the lossy nature of wireless communication. This can lead to situations, where nodes lose synchrony and programs reach arbitrary states. Traditional approaches to fault tolerance like fault masking or global resets are not feasible for WSNs. Applying the concepts of self-stabilisation to achieve fault tolerance is a promising concept. However, the majority of self-stabilising algorithms found in the literature is based on models not suitable for WSNs. This paper proposes a problem-independent transformation for algorithms that stabilise under the central daemon scheduler such that they meet the demands of a WSN. Furthermore, a comparison with transformers from the literature is made through a series of simulations. Finally, the proposed transformer is evaluated with a real sensor network in a field test.
Bernd Hauck. Worst-Case Analysis of a Self-Stabilizing Algorithm Computing a Weakly Connected Minimal Dominating Set. Technical Report urn:nbn:de:gbv:830-tubdok-5126, Hamburg University of Technology, Hamburg, Germany, Oktober 2008.
[BibTeX] [Abstract] [PDF]
@TechReport{Telematik_Hauck_2008_WorstCaseSelfStabilizingWeaklyConnectedMDSet, author = {Bernd Hauck}, title = {Worst-Case Analysis of a Self-Stabilizing Algorithm Computing a Weakly Connected Minimal Dominating Set}, number = {urn:nbn:de:gbv:830-tubdok-5126}, institution = {Hamburg University of Technology}, address = {Hamburg, Germany}, month = oct, year = 2008, }
Abstract: Recently, Srimani and Xu presented a self-stabilizing algorithm that computes a weakly connected minimal dominating set. They prove an upper bound of O(2^n) until stabilization but they do not provide a lower bound. This paper verifies by giving an example that their algorithm indeed requires O(2^n) moves on a certain graph.
Volker Turau. Linear Self-Stabilizing Algorithms for the Independent and Dominating Set Problems using an Unfair Distributed Scheduler. Information Processing Letters., 103(3):88–93, Juli 2007.
[BibTeX] [Abstract] [DOI] [PDF]
@Article{Telematik_TT_2007_Selfstabilizing, author = {Volker Turau}, editor = {A. Tarlecki}, title = {Linear Self-Stabilizing Algorithms for the Independent and Dominating Set Problems using an Unfair Distributed Scheduler}, pages = {88-93}, journal = {Information Processing Letters.}, volume = {103}, number = {3}, month = jul, year = 2007, }
Abstract: This paper presents distributed self-stabilizing algorithms for the maximal independent and the minimal dominating set problems. Using an unfair distributed scheduler the algorithms stabilizes in at most max{3n-5,2n} resp. 9n moves. All previously known algorithms required O(n2) moves.
Volker Turau und Christoph Weyer. Randomized Self-stabilizing Algorithms for Wireless Sensor Networks. In Proceedings of the First International Workshop on Self-Organizing Systems (IWSOS'06), September 2006, pp. 74–89. Passau, Germany.
[BibTeX] [Abstract] [DOI] [PDF] [Folien]
@InProceedings{Telematik_TW_2006_RandomizedSelfStabilizing, author = {Volker Turau and Christoph Weyer}, title = {Randomized Self-stabilizing Algorithms for Wireless Sensor Networks}, booktitle = {Proceedings of the First International Workshop on Self-Organizing Systems (IWSOS'06)}, pages = {74-89}, day = {18-20}, month = sep, year = 2006, location = {Passau, Germany}, }
Abstract: Wireless sensor networks (WSNs) pose challenges not present in classical distributed systems: resource limitations, high failure rates, and ad hoc deployment. The lossy nature of wireless communication can lead to situations, where nodes lose synchrony and programs reach arbitrary states. Traditional approaches to fault tolerance like replication or global resets are not feasible. In this work, the concept of self-stabilization is applied to WSNs. The majority of self-stabilizing algorithms found in the literature is based on models not suitable for WSNs: shared memory model, central daemon scheduler, unique processor identifiers, and atomicity. This paper proposes problem-independent transformations for algorithms that stabilize under the central daemon scheduler such that they meet the demands of a WSN. The transformed algorithms use randomization and are probabilistically self-stabilizing. This work allows to utilize many known self-stabilizing algorithms in WSNs. The proposed transformations are evaluated using simulations and a real WSN.

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