1421735
Scalable Self-Stabilization
This paper presents a methodology for a synchronous non-reactive distributed system on a tree topology to stabilize from a k-faulty configuration in a time independent of the size n of the system. In the proposed methodology, processes first measure and compare the sizes of the faulty regions, and then use this information to schedule actions in such a way that the size of the faulty regions progressively shrink, until they completely disappear. We demonstrate that when k processes fail, the stabilization time is O(k2). Apart from its applicability to a wide class of problems, the proposed method achieves scalability with a low space complexity of O(�.(�.k+log2n)) per process, where � is the maximum degree of a node.
31511581
Mutual Exclusion on a Hypercube
Abstract We present a decentralized, symmetric mutual exclusion algorithm that is tailored to the hypercube architecture. Our algorithm has better time complexity than a suitable hypercube adaptation of Maekawa′s O(√N) Mutual Exclusion algorithm. We show that, in the presence of contention, our algorithm has a shorter Blocking Delay than Maekawa′s algorithm. In the absence of contention, our algorithm achieves optimal Round-trip Delay under both the n-port and the one-port communication models.
3086074
An Exercise in Fault-Containment: Self-Stabilizing Leader Election
Self-stabilizing algorithms are designed to guarantee convergence to some desired stable state from arbitrary initial states arising out of an arbitrarily large number of faults. However, in a well-designed system, the simultaneous occurrence of a large number of faults is rare. It is therefore desirable to design algorithms that are not only self-stabilizing, but also have the ability to recover very fast from a bounded number of faults. As an illustration, we present a simple self-stabilizing leader election protocol that recovers in O(1) time from a state with a single transient fault on oriented rings. Only the faulty node and its two neighbors change their state during convergence to a stable state. Thus, the effect of a single fault is tightly contained around the fault. The technique for transforming a self-stabilizing algorithm into its fault-contained version is simple and general, and can be applied to other problems as well that satisfy certain properties.
32010004
Binary Self-Stabilization in Distributed Systems
Abstract Dijkstra introduced the problem of self-stabilization in distributed systems as an interesting exercise for achieving global convergence using local actions. In all the papers dealing with self-stabilizing systems so far, it has been assumed that each component machine of the distributed system has at least three states. This paper illustrates that it is feasible to design a self-stabilizing system with two-state or binary machines at the expense of a larger atomicity.
34174199
Selfish Stabilization
11125013
A self-stabilizing algorithm for coloring planar graphs
SummaryThis paper describes an algorithm for coloring the nodes of a planar graph with no more than six colors using a self-stabilizing approach. The first part illustrates the coloring algorithm on a directed acyclic version of the given planar graph. The second part describes a selfstabilizing algorithm for generating the directed acyclic version of the planar graph, and combines the two algorithms into one.
7750491
Revisiting correlations and scheduling in Web servers
Mathematical models play an important role in the design, analysis, control, optimization, management andplanning of Web server systems. To be most effective in each of these areas, such models must capture in sufficient detail the key characteristics of Web server workloads, the key characteristics of Web server scheduling policies for executing these workloads, and the impact of these workload and scheduling policy characteristics on Web server performance and related measures . Of particular interest in our study are very efficient mathematical methods that can be exploited online to support an increasingly important range of real-time applications (e .g., dynamic control of quality of service in Web servers to best satisfy service-level agreements), as well as in efficient interactive tools often used offline for many different purposes (e.g., what-ifanalysis and stochastic optimization for capacity planning). A significant body of research has investigated the workloads found in practice at a wide variety of Web server environments ; e.g ., see [1, 8, 18]. Most of these studies have demonstrated that the client request patterns exhibited at many different types of Web server environments have strong dependence structures and that the requested files sizes at these Web servers are independent and identically distributed (i .i .d.) according to a heavy-tailed or subexponential distribution . However, the vast majority of these studies appear to have completely ignored the issue of whether there is any correlation between the client request arrival times and the requested file sizes or the request service times. This includes studies of Web server workload characterization and generation, Web server performance models, and Web server scheduling policies . In this study, we consider data from various commercial Web server environments to revisit the issues of different forms of correlation in these Web server workloads and their implications on Web server performance and scheduling policies . Theresults ofour data analysis demonstrate the existence ofsignificant dependencies between the client request interarrival times and the corresponding file sizes and service times. Our analysis also shows a strong dependence structure within the interarrival process of client requests, whereas the sequence of service times is essentially i .i .d . To the best ofour knowledge, this is the first study to identify and quantify significant dependencies between the arrival and service processes in Web server environments (as opposed to network environments, where this issue goes all the way back to Kleinrock [15]). We then investigate the source of this cross correlation between the client request interarrival times and the corresponding file sizes and service times. The results of our data analysis support the view that such cross correlations are primarily due to certain mixing effects involving the superposition of different classes of client requests each with different service requirements . We next turn to consider a mathematical analysis of queueing Mark S. Squillante Mathematical Sciences Department IBM Thomas J. Watson Research Center Yorktown Heights, NY 10598, USA mss@watson .ibm .com
6735470
FraNtiC: A Fractal Geometric Framework for Mesh-Based Wireless Access Networks
The design of the access networks of next generation broadband wireless systems requires special attention in the light of changing network characteristics. In this paper, we present a mesh-based distributed radio access network (RAN) framework for future wireless systems. Using short, high bandwidth optical wireless links to interconnect the various network elements, we identify a generic fractal or self similar structure in the network. A mathematical model for the framework is presented and the benefits of its scale-invariant properties on robustness, reliability and flexibility analyzed. We focus on three design parameters - carrier-class network reliability, network exposure due to failure conditions and system cost. The dynamics of these parameters on our proposed architecture are studied and compared against existing access network topologies like tree/ring and square-grid. The generality and recursive nature of our framework lends itself to be applied in interconnecting various heterogeneous broadband wireless access networks of the future
7868276
Automatic Recognition of Landforms on Mars Using Terrain Segmentation and Classification
Mars probes send back to Earth enormous amount of data. Automating the analysis of this data and its interpretation represents a challenging test of significant benefit to the domain of planetary science. In this study, we propose combining terrain segmentation and classification to interpret Martian topography data and to identify constituent landforms of the Martian landscape. Our approach uses unsupervised segmentation to divide a landscape into a number of spatially extended but topographically homogeneous objects. Each object is assigned a 12 dimensional feature vector consisting of terrain attributes and neighborhood properties. The objects are classified, based on their feature vectors, into predetermined landform classes. We have applied our technique to the Tisia Valles test site on Mars. Support Vector Machines produced the most accurate results (84.6% mean accuracy) in the classification of topographic objects. An immediate application of our algorithm lies in the automatic detection and characterization of craters on Mars.
14224064
PeterNet: an emergent technology based radio access network architecture for next generation cellular wireless systems
For next generation wireless cellular networks, the radio access network (RAN) component is destined to evolve into a high-capacity, flexible and reconfigurable network architecture supporting smaller cell sites and newer technologies. Based on the well-known Petersen graph, in this paper we propose a RAN architecture, named PeterNet, that interconnects the network elements in a mesh topology. Focusing on optical wireless as the underlying transmission technology, we analyze our architecture on two key indices - carrier-class network reliability (99.999%) and infrastructure cost - providing comparative performance analysis with existing tree/star and regular grid networks. Furthermore, we generalize our architecture to what we call, the GPeterNet, which allows dynamic reconfiguration and redesign of the access network while leveraging the underlying salient features.
1136530
A graph-theoretic approach for studying the convergence of fractal encoding algorithm
In this paper, we present a graph-theoretic interpretation of convergence of fractal encoding based on partial iterated function system (PIFS). First we have considered a special circumstance, where no spatial contraction has been allowed in the encoding process. The concept leads to the development of a linear time fast decoding algorithm from the compressed image. This concept is extended for the general scheme of fractal compression allowing spatial contraction (on averaging) from larger domains to smaller ranges. A linear time fast decoding algorithm is also proposed in this situation, which produces a decoded image very close to the result obtained by an ordinary iterative decompression algorithm.