Search results for "dependability"

System times and channel availability analyses in multi-channel cognitive radio networks

2014

Channel accessibility by a secondary user (SU) in cognitive radio networks (CRNs) depends on the availability of the spectrum based on primary user and other SU activities. A new SU request may be blocked and an ongoing SU service may also be discarded if no sufficient spectrum is available. So far, little work has been done to analyze the reliability and availability aspects of CRNs from the perspective of the dependability theory. In this paper, we introduce the concept of availability for spectrum access in multi-channel CRNs, which is defined as the fraction of time that a CRN can allocate at least the minimum number of required channels for a new SU request. Through a proposed continuo…

Information Integration Platform for Patient-Centric Healthcare Services: Design, Prototype and Dependability Aspects

2014

Published version of an article in the journal: Future Internet. Also available from the publisher at: http://dx.doi.org/10.3390/fi6010126 Open Access Technology innovations have pushed today’s healthcare sector to an unprecedented new level. Various portable and wearable medical and fitness devices are being sold in the consumer market to provide the self-empowerment of a healthier lifestyle to society. Many vendors provide additional cloud-based services for devices they manufacture, enabling the users to visualize, store and share the gathered information through the Internet. However, most of these services are integrated with the devices in a closed “silo” manner, where the devices can…

Fault Injection into VHDL Models: Experimental Validation of a Fault-Tolerant Microcomputer System

1999

This work presents a campaign of fault injection to validate the dependability of a fault tolerant microcomputer system. The system is duplex with cold stand-by sparing, parity detection and a watchdog timer. The faults have been injected on a chip-level VHDL model, using an injection tool designed with this purpose. We have carried out a set of injection experiments (with 3000 injections each), injecting transient and permanent faults of types stuck-at, open-line and indetermination on both the signals and variables of the system, running a workload. We have analysed the pathology of the propagated errors, measured their latency, and calculated both detection and recovery coverage. We have…

Virtual Environment for Implementation and Testing Private Wide Area Network Solutions

2013

In this paper the concept of virtual environment for implementation and testing private Wide Area Network (WAN) solutions is presented. The VMware vSphere virtualization platform is used. The paper presents the ability to reflect the structure of any given WAN topology using Vyatta software routers and VMware virtualization platform and verifies its reliability regarding data transfer. The paper includes a number of performance tests to verify the dependability of the proposed solution and provide a proof-of-concept for the network topology during the Design phase of the PPDIOO methodology, right before the Implementation phase.

HybridS: A Scheme for Secure Distributed Data Storage in WSNs

2008

In unattended wireless sensor networks (WSNs), data is stored locally or at designated nodes upon sensing, and users can access it on demand. This paradigm can improve energy efficiency by making use of the upcoming cheap and large flash memory, as well as system robustness. Nevertheless, the security and dependability of distributed storage are critical for the applicability of such WSNs. In this paper, we propose a secure and dependable data storage scheme by taking advantages of secret sharing and Reed-Solomon code, which has computational security and yet maintains optimal data size. The extensive analysis verifies our scheme can provide secure and dependable data storage in WSNs in the…

On benchmarking the dependability of automotive engine control applications

2004

The pervasive use of ECUs (electronic control units) in automotive systems motivates the interest of the community in methodologies for quantifying their dependability in a reproducible and cost-effective way. Although the core of modern vehicle engines is managed by the control software embedded in engine ECUs, no practical approach has been proposed so far to characterise the impact of faults on the behaviour of this software. This paper proposes a dependability benchmark for engine control applications. The essential features of such type of applications are first captured in a general model, which is then exploited in order to specify a standard procedure to assess dependability measure…

Advanced Stochastic Petri Net Modeling with the Mercury Scripting Language

2017

Formal models are widely used in performance and dependability studies of computational systems. Graphical modeling tools allow users to compose such models with ease, but they complicate the creation of models with a dynamic/complex structure, the hierarchical arrangement of different models, and the automatic execution of models with different parameter configurations. To overcome this problem, we created a scripting language for the Mercury tool that supports the combination of different modeling approaches (e.g., Stochastic Petri Nets and Reliability Block Diagrams) in a single project. In this paper, we focus on the extensions developed to improve the capabilities of Generalized Stocha…

2020

The growth of cloud-based services is mainly supported by the core networking infrastructures of large-scale data centers, while the scalability of these services is influenced by the performance and dependability characteristics of data centers. Hence, the data center network must be agile and reconfigurable in order to respond quickly to the ever-changing application demands and service requirements. The network must also be able to interconnect the big number of nodes, and provide an efficient and fault-tolerant routing service to upper-layer applications. In response to these challenges, the research community began exploring novel interconnect topologies, namely: Flecube, DCell, Ficonn…

Dependability-Based Reliability Analysis in URC Networks: Availability in the Space Domain

2019

Ultra-reliable low latency communication (URLLC), which refers to achieving almost 100% reliability at a certain (satisfactory) level of services and stringent latency, is one of the key requirements for 5G networks. However, most prior studies on reliable communication did not address space domain analysis. Neither were they pursued from a dependability perspective. This paper addresses the ultra-reliable communication (URC) aspect of URLLC and aims at advocating the concept of URC from a dependability perspective in the space domain. We perform in-depth analysis on URC considering both the spatial characteristics of cell deployment and user distributions, as well as service requirements. …

System Times and Channel Availability for Secondary Transmissions in CRNs: A Dependability Theory based Analysis

2017

[EN] Reliability is of fundamental importance for the performance of secondary networks in cognitive radio networks (CRNs). To date, most studies have focused on predicting reliability parameters based on prior statistics of traffic patterns from user behavior. In this paper, we define a few reliability metrics for channel access in multichannel CRNs that are analogous to the concepts of reliability and availability in classical dependability theory. Continuous-time Markov chains are employed to model channel available and unavailable time intervals based on channel occupancy status. The impact on user access opportunities based on channel availability is investigated by analyzing the stead…