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A self-stabilizing algorithm, after transient faults hit the system and place it in some arbitrary global state, causes the system to recover in finite time without external (e.g., human) intervention. In this paper, we give a distributed asynchronous silent self-stabilizing algorithm for finding a minimal k-dominating set of at most n k+1 processes in an arbitrary identified network of size n. We give a transformer that allows our algorithm to work under an unfair daemon, the weakest scheduling assumption. The complexity of our solution is O(n) rounds and O(Dn 3 ) steps using O(log k + log n + k log N k ) bits per process, where D is the diameter of the network and N is an upper bound on n.

A k-cluster of a graph is a connected non-empty subgraph C of radius at most k, i.e., all members of C are within distance k of a particular node of C, called the clusterhead of C. A k-clustering of a graph is a partitioning of the graph into distinct k-clusters. Finding a minimum cardinality k-clustering is known to be N P-hard. In this paper, we propose a silent self-stabilizing asynchronous distributed algorithm for constructing a k-clustering of any connected network with unique IDs. Our algorithm stabilizes in O(n) rounds, using O(log n) space per process, where n is the number of processes. In the general case, our algorithm constructs O( n k ) k-clusters. If the network is a Unit Disk Graph (UDG), then our algorithm is 7.2552k + O(1)-competitive, that is, the number of kclusters constructed by the algorithm is at most 7.2552k + O(1) times the minimum possible number of k-clusters in any k-clustering of the same network. More generally, if the network is an Approximate Disk Graph (ADG) with approximation ratio λ, then our algorithm is 7.2552λ 2 k + O(λ)-competitive. Our solution is based on the self-stabilizing construction of a data structure called the MIS Tree, a spanning tree of the network whose processes at even levels form a maximal independent set of the network. The MIS tree construction is the time bottleneck of our k-clustering algorithm, as it takes Θ(n) rounds in the worst case, while the remainder of the algorithm takes O(D) rounds, where D is the diameter of the network. We would like to improve that time to be O(D), but we show that our distributed MIS tree construction is a P-complete problem.

In this article, experimental results on the Routing Protocol for Low-Power and Lossy Networks (RPL) are presented. We study the RPL properties in terms of delivery ratio, control packet overhead and dynamicity. The results are obtained by several experimentations conducted in a large wireless sensor network testbed composed of more than 250 sensor nodes. In this real-life scenario (high density and convergcast traffic), several intrinsic characteristics of RPL are underlined: path length stability but reduced delivery ratio and important overhead. To the best of our knowledge, it is the first study of RPL on a such large platform.

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The use of localization mechanism is essential in wireless sensor networks either for communication protocols (geographic routing protocol) or for application (vehicle tracking). The goal of localization mechanism is to determine either precisely or coarsely the node location using either a global reference (GPS) or a locale one. In this work, we introduce a new localized algorithm which classified the proximity of the neighborhood for a node. This qualitative localization does not use any anchor or dedicated hardware like a GPS. Each node builds a Qualitative Distance Table according to the 2-hop neighborhood informations. Thus, the algorithm allows to determine coarsely the location of the neighbors which are classified as very close, close or far. The algorithm is analyzed on a regular particular topology and then we evaluate this accuracy on a random topologies. We apply this algorithm for a localized topology control and we show that these topology control algorithms remain effective even without GPS information.

To gather and transmit data, low cost wireless devices are often deployed in open, unattended and possibly hostile environment, making them particularly vulnerable to physical attacks. Resilience is needed to mitigate such inherent vulnerabilities and risks related to security and reliability. In this paper, Routing Protocol for Low-Power and Lossy Networks (RPL) is studied in presence of packet dropping malicious compromised nodes. Random behavior and data replication have been introduced to RPL to enhance its resilience against such insider attacks. The classical RPL and its resilient variants have been analyzed through Cooja simulations and hardware emulation. Resilient techniques introduced to RPL have enhanced significantly the resilience against attacks providing route diversification to exploit the redundant topology created by wireless communications. In particular, the proposed resilient RPL exhibits better performance in terms of delivery ratio (up to 40%), fairness and connectivity while staying energy efficient.1550-445X/15 $31.00