The Infona portal uses cookies, i.e. strings of text saved by a browser on the user's device. The portal can access those files and use them to remember the user's data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser.
We present a synchronization algorithm that is able to let the nodes in a sensor network perform a certain task at a given point in time. In contrast to other time synchronization algorithms we do not provide a global time basis that is shared on all nodes. Instead, any node in the network can spontaneously initiate a process that allows the synchronous execution of arbitrary tasks. We show that our...
In recent years, real-time database technology in the military data fusion system has been closely followed and applied more and more. In order to complete the design of background database for data fusion system, first analyzed the data fusion system's requirements on database system, and then the organizational structure was determined, the real-time protocol was designed to process the real-timing...
Reflector attacks are a variant of denial-of-service attacks that use unwitting, legitimate servers to flood a target. The attacker spoofs the target's address in legitimate service requests, such as TCP SYN packets. The servers, called "reflectors,'' reply to these requests, flooding the target. RAD is a novel defense against reflector attacks. It has two variants -- locally-deployed (L-RAD)...
OMA DS is used by the Content Storage Client and the Content Storage Server for synchronization, as defined in the OMA CPM Architecture. But most of the Synchronization systems are designed for flat structure data, which cannot be applied to the synchronization of hierarchical directory structure in CPM (Converged IP Messaging) directly. In order to fulfill the requirement of content synchronization...
In this article we extend previous results for back-stepping and passivity-based design of cooperative control laws to a class of chained form systems that includes certain drift-free nonholonomic systems. We exploit the cascaded structure and feedback equivalence to passive systems to derive suitable control laws using a modified backstepping methodology. A virtual output is obtained and shared within...
We propose a new method that accelerates existing Byzantine Fault Tolerance (BFT) protocols for asynchronous distributed systems by parallelizing the involved consensuses. BFT realizes a reliable system against Byzantine failures and is usually solved by repeatedly executing consensus for a set of requests. Our method consistently parallelizes the consensus by introducing a new extra consensus on...
Implementing a workflow using previously implemented services is a typical task while dealing with Service-oriented Architectures (SOA). Defining these workflows is the task of business (process) analysts in tight collaboration with clients or domain experts. Unfortunately these analysts only have a sketchy view on the Service-oriented Architecture, thus they do not know which investigations a specific...
We propose a general analysis method for recursive, concurrent programs that tracks effectively procedure calls and returns in a concurrent context, even in the presence of unbounded recursion and infinite-state variables like integers. This method generalizes the relational interprocedural analysis of sequential programs to the concurrent case. We implemented it for programs with scalar variables,...
An increasing demand for applications in the area of Ultra-Wideband Radio Technology led to the EUWB (Coexisting Short Range Radio by Advanced Ultra-Wideband Radio Technology, FP7-ICT-215669, www.euwb.eu) project, which has been started in April 2008. The goal of this industry-led initiative of major industrial and excellent academic organizations is the improvement, integration, and the applications...
Computer architectures make a dramatic turn away from improving single-processor performance towards improved parallel performance through integrating many cores in one chip. However, providing directory based coherence protocols for these platforms is too complex and expensive. As a substitute, we propose a synchronization based cache coherence solution, which uses different cache policies according...
The outage behavior of amplify-and-forward (AF) relaying protocol over an asynchronous cooperative network is examined when orthogonal frequency division multiplexing (OFDM) is used to combat synchronization error among the transmitting nodes. We consider non-orthogonal AF (NAF) and orthogonal1 AF (OAF) protocols, respectively, over a single relay and a two relay cooperative network and analyze the...
In this paper specific variants of delay attacks are examined. First, the Network Time Protocol is regarded. Second, delay attacks and implications on the time synchronization of the Precise Time Protocol are described. In particular, consequences for the offset calculation Oprox are regarded. At the end of the paper possible countermeasurements are described.
The time accuracy of the Precision Time Protocol deteriorates in consequence to Delayreq/Delayresp session collisions common for applications using shared broadcast media. In this paper we propose a protocol that coordinates Delay_req/Delay_resp sessions with minimum changes to the original PTP protocol. Simulations illustrate protocol's operation and demonstrate significant reduction of session collisions.
In this paper we suggest a protocol for secure data distribution in a one-way communication scenario aimed at time distribution for sensor networks. Our protocol is designed to support timestamps in any format, including repeating, resettable, and incomplete timestamps. The protocol requires a trusted powerful source node. We show that the protocol is immune to attacks including replay attacks, wormhole...
Synchronized clocks are fundamental for multiple applications sometimes also requiring to protect clock synchronization protocol information against malicious attacks. This article analyses security vulnerabilities of the IEEE 1588 clock synchronization protocol caused by a flaw in the integrity check value (ICV) calculation. The paper elaborates counter measures that protect protocol addresses and...
Two techniques have been proposed in the literature to improve the scalability of QoS scheduling in the core of the Internet: flow aggregation and dynamic packet scheduling (DPS). These techniques reduce or eliminate the amount of state maintained by each router in a core network. Flow aggregation combines multiple individual flows into a single aggregate flow (and thus reducing the per-flow state...
The recent proliferation of Grid environments for eScience applications led to common computing infrastructures with nearly unlimited storage capabilities. In terms of data management, the Grid allows keeping a large number of replicas of data objects to allow for a high degree of availability, reliability and performance. Due to the particular characteristics of the Grid, especially due to the absence...
Adapting router buffer sizing rules and TCP's congestion control to Gbit/s link speeds has been the subject of many studies and proposals. In a previous work (Hassayoun and Ros, 2008), we found that high-speed versions of TCP may be prone to strong packet-loss synchronization between flows. Given that synchronized losses may lead to oscillatory behavior in router queues, a relatively large amount...
This paper introduces a formal model of the distributed commit protocols in the process algebra mCRL2 and also their general requirements in the modal ??-calculus. We show how to make straightforward models of protocols and by doing so, how it becomes easy to identify problems. We apply this to the well-known Two-Phase Commit Protocol (2PC) and prove it problematic for single site failure. We also...
In a consensus problem, autonomous agents constituting a dynamical system communicate with one another to reach agreement on certain quantities of interest. By merging control theory and spectral graph theory, we generalize the previous consensus problems under nonlinear protocols for networks with undirected graphs to directed graphs. We prove that, when the nonlinear protocol is strictly increasing,...
Set the date range to filter the displayed results. You can set a starting date, ending date or both. You can enter the dates manually or choose them from the calendar.