515 research outputs found
ROCRSSI++: An Efficient Localization Algorithm for Wireless Sensor Networks
No full textLocalization within a Wireless Sensor Network consists of defining the position of a given set of sensors by satisfying some non-functional requirements such as (1) efficient energy consumption, (2) low communication or computation overhead, (3) no, or limited, use of particular hardware components, (4) fast localization, (5) robustness, and (6) low localization error. Although there are several algorithms and techniques available in literature, localization is viewed as an open issue because none of the current solutions are able to jointly satisfy all the previous requirements. An algorithm called ROCRSSI appears to be a suitable solution; however, it is affected by several inefficiencies that limit its effectiveness in real case scenarios. This paper proposes a refined version of this algorithm, called ROCRSSI++, which resolves such inefficiencies using and storing information gathered by the sensors in a more efficient manner. Several experiments on actual devices have been performed. The results show a reduction of the localization error with respect to the original algorithm. This paper investigates energy consumption and localization time required by the proposed approach
Efficient Range-free RSSI Localization Technique for Wireless Sensor Networks
No full textLocalization within a Wireless Sensor Network consists of defining the position of a given set of sensors by satisfying some non-functional requirements such as (i) eff
Leveraging Power of Transmission for Range-Free Localization of Tiny Sensors
No full textModern environmental monitoring systems are being envisioned as constellations of tiny smart sensors, densely deployed on the territory to be monitored. Data provided by such sensors is meaningless if it is not equipped with information about the context to which it refers. Such a context is mainly related to the location of sensors, which allows to manage collected data by means of Geographic Information Systems. Due to scarce resources of tiny sensors characteristics, localization services are usually range-free and based on simple measurements provided by the majority of radio chips, such as the Received Signal Strength Indicator (RSSI). However, existing solutions suffer of inaccuracy issues, due to the unreliability of the adopted indicators. This article proposes a range-free localization algorithm based on data fusion, which combines the RSSI with the Power of Transmission (PoT), by estimating the RSSI at different PoT levels. We show, through experimentation on real tiny devices, how this simple solution allows reducing the localization error to about 16% with respect to state-of-art algorithms
State-based robustness testing of IaaS cloud platforms
No full textAn uncountable number of services are deployed over cloud platforms and provided to millions of consumers. As this paradigm spreads over, the quality of provided services becomes a primary concern. Testing helps in making software reliable, but it has been overlooked for cloud. In this paper, we present a method for the robustness testing of software platforms for IaaS cloud. The method stresses the importance of considering the state for these systems, which are characterized by phase-based interactions of many software components with multiple concurrent users. Applied to a real cloud platform, the method exposes failures hard to uncover with common robustness testing approaches
Impact of Malfunction on the Energy Efficiency of Batch Processing Systems
No full textEnergy efficiency of large processing systems is usually assessed as the relation between a performance and a
power consumption metric, neglecting malfunction. Execution
failures have a tangible cost in terms of wasted energy, however. They are often managed through fault tolerance mechanisms, which in turn consume electricity.
We introduce the consumability attribute for batch processing systems, encompassing performance, consumption, and dependability aspects altogether. We propose a metric for its quantification and a methodology for its analysis. Using a real 500-node batch system as a case study, we show that consumability is representative of both efficiency and effectiveness, and we show the usefulness of the proposed metric and the suitability of the proposed methodology
Cost-Benefit Analysis of Virtualizing Batch Systems: Performance-Energy-Dependability Trade-offs
No full textPerformance, energy efficiency, and dependability are key characteristics of batch systems, which can be differently affected when adopting virtualization. Scientific literature usually analyzes the variation with respect to different config- urations of one characteristic, or the trade-off between two. In this paper, instead, we assess the impact of virtualization encompassing all of them. Results show that the joint analysis helps in finding the proper tuning of the system for balancing costs and benefits due to virtualization and related techniques
Reproducibility of Software Bugs Basic Concepts and Automatic Classification
No full textUnderstanding software bugs and their effects is important in several engineering activities, including testing, debugging, and design of fault containment or tolerance methods. Dealing with hard-to-reproduce failures requires a deep comprehension of the mechanisms leading from bug activation to software failure. This chapter surveys taxonomies and recent studies about bugs from the perspective of their reproducibility, providing insights into the process of bug manifestation and the factors influencing it. These insights are based on the analysis of thousands of bug reports of a widely used open source software, namely MySQL Server. Bug reports are automatically classified according to reproducibility characteristics, pro- viding figures about the proportion of bugs hardly reproducible, about their features, and about their evolution over releases
Performance degradation analysis of a supercomputer
No full textWe analyze performance degradation phenomena due to software aging on a real supercomputer deployed at the Federico II University of Naples, by considering a dataset of ten months of operational usage. We adopted a statistical approach for identifying when and where the supercomputer experienced a performance degradation trend. The analysis pinpointed performance degradation trends that were actually caused by the gradual error accumulation within basic software of the supercomputer
A comprehensive survey on the security of low power wide area networks for the Internet of Things
No full textWhile the spreading of the Internet of Things continues beyond expectations, the security of networking technologies used in this context remains an open issue. This paper provides a comprehensive overview of the state of the art on the security of Low Power Wide Area Networks (LPWANs), with a focus on Sigfox, LoRaWAN, and Narrowband Internet of Things. The paper covers five main areas: (1) security requirements and their implementation in these networks, such as authentication, encryption, access control, and key management; (2) categorization of attacks and threat modeling, with the identification of the attack vectors and the presentation of an attack categorization and analysis; (3) a detailed explanation of attacks documented on Sigfox, LoRaWAN, and Narrowband Internet of Things, examining the underlying vulnerabilities exploited, outlining potential consequences, and discussing countermeasures proposed to mitigate these attacks; (4) security enhancements proposed to address vulnerabilities in each network; (5) the integration of LPWANs with 5G and the consequent security challenges. This survey constitutes an important and missing resource for the study and the development of secure Internet of Things solutions based on Low Power Wide Area Networks, raising awareness of potential threats, and guiding future research efforts towards strengthening the security of these networks and of the broader IoT landscape
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