NB-IoT via LEO satellites: An efficient resource allocation strategy for uplink data transmission

in IEEE Internet of Things Journal (2021)

Uncertainty-aware Specification and Analysis for Hardware-in-the-Loop Testing of Cyber Physical Systems

in Journal of Systems and Software (2021)

Hardware-in-the-loop (HiL) testing is important for developing cyber physical systems (CPS). HiL test cases manipulate hardware, are time-consuming and their behaviors are impacted by the uncertainties in ... [more ▼]

Hardware-in-the-loop (HiL) testing is important for developing cyber physical systems (CPS). HiL test cases manipulate hardware, are time-consuming and their behaviors are impacted by the uncertainties in the CPS environment. To mitigate the risks associated with HiL testing, engineers have to ensure that (1) test cases are well-behaved, e.g., they do not damage hardware, and (2) test cases can execute within a time budget. Leveraging the UML profile mechanism, we develop a domain-specific language, HITECS, for HiL test case specification. Using HITECS, we provide uncertainty-aware analysis methods to check the well-behavedness of HiL test cases. In addition, we provide a method to estimate the execution times of HiL test cases before the actual HiL testing. We apply HITECS to an industrial case study from the satellite domain. Our results show that: (1) HITECS helps engineers define more effective assertions to check HiL test cases, compared to the assertions defined without any systematic guidance; (2) HITECS verifies in practical time that HiL test cases are well-behaved; (3) HITECS is able to resolve uncertain parameters of HiL test cases by synthesizing conditions under which test cases are guaranteed to be well-behaved; and (4) HITECS accurately estimates HiL test case execution times. [less ▲]

An Uplink UE Group-Based Scheduling Technique for 5G mMTC Systems Over LEO Satellite

in IEEE Access (2019)

Narrowband Internet of Things (NB-IoT) is one of the most promising IoT technology to support the massive machine-type communication (mMTC) scenarios of the fifth generation mobile communication (5G ... [more ▼]

Narrowband Internet of Things (NB-IoT) is one of the most promising IoT technology to support the massive machine-type communication (mMTC) scenarios of the fifth generation mobile communication (5G). While the aim of this technology is to provide global coverage to the low-cost IoT devices distributed all over the globe, the vital role of satellites to complement and extend the terrestrial IoT network in remote or under-served areas has been recognized. In the context of having the global IoT networks, low earth (LEO) orbits would be beneficial due to their smaller propagation signal loss, which for the low complexity, low power, and cheap IoT devices is of utmost importance to close the link-budget. However, while this would lessen the problem of large delay and signal loss in the geostationary (GEO) orbit, it would come up with increased Doppler effects. In this paper, we propose an uplink scheduling technique for a LEO satellite-based mMTC NB-IoT system, able to mitigate the level of the differential Doppler down to a value tolerable by the IoT devices. The performance of the proposed strategy is validated through numerical simulations and the achievable data rates of the considered scenario are shown, in order to emphasize the limitations of such systems coming from the presence of a satellite channel. [less ▲]

HITECS: A UML Profile and Analysis Framework for Hardware-in-the-Loop Testing of Cyber Physical Systems

in Proceedings of ACM/IEEE 21st International Conference on Model Driven Engineering Languages and Systems (MODELS’18) (2018, October)

Hardware-in-the-loop (HiL) testing is an important step in the development of cyber physical systems (CPS). CPS HiL test cases manipulate hardware components, are time-consuming and their behaviors are ... [more ▼]

Hardware-in-the-loop (HiL) testing is an important step in the development of cyber physical systems (CPS). CPS HiL test cases manipulate hardware components, are time-consuming and their behaviors are impacted by the uncertainties in the CPS environment. To mitigate the risks associated with HiL testing, engineers have to ensure that (1) HiL test cases are well-behaved, i.e., they implement valid test scenarios and do not accidentally damage hardware, and (2) HiL test cases can execute within the time budget allotted to HiL testing. This paper proposes an approach to help engineers systematically specify and analyze CPS HiL test cases. Leveraging the UML profile mechanism, we develop an executable domain-specific language, HITECS, for HiL test case specification. HITECS builds on the UML Testing Profile (UTP) and the UML action language (Alf). Using HITECS, we provide analysis methods to check whether HiL test cases are well-behaved, and to estimate the execution times of these test cases before the actual HiL testing stage. We apply HITECS to an industrial case study from the satellite domain. Our results show that: (1) HITECS is feasible to use in practice; (2) HITECS helps engineers define more complete and effective well-behavedness assertions for HiL test cases, compared to when these assertions are defined without systematic guidance; (3) HITECS verifies in practical time that HiL test cases are well-behaved; and (4) HITECS accurately estimates HiL test case execution times. [less ▲]

Resource Allocation Approach for Differential Doppler Reduction in NB-IoT over LEO Satellite

in 9th Advanced Satellite Multimedia Systems Conference (ASMS) and 15th Signal Processing for Space Communications Workshop (SPSC), Berlin, Germany, 10-12 September 2018 (2018)

Internet of things (IoT) over satellite is an attractive system architecture which has been proposed as a key-enabling technology, to extend the coverage in remote areas (e.g. desert, ocean, forest, etc ... [more ▼]

Internet of things (IoT) over satellite is an attractive system architecture which has been proposed as a key-enabling technology, to extend the coverage in remote areas (e.g. desert, ocean, forest, etc), particularly where a terrestrial network is impossible or impractical to reach. One of the most promising technologies that fit the IoT vision of low-power, wide area networks (LPWAN) is the narrowband IoT (NB-IoT). While low earth orbit (LEO) satellites are favourable because of their lower round trip time (RTT) and lower propagation loss in the communication link, they come up with a significantly increased Doppler shift. In our NB-IoT over LEO satellite architecture, we identify the problem of high differential Doppler among channels of different users on Earth, which leads to the performance degradation of our system. In this paper, we propose a resource allocation approach in order to reduce the high values of differential Doppler under the maximum value supported by the standard itself. [less ▲]

Centralized Rainfall Estimation using Carrier-to-Noise of Satellite Communication Links

in IEEE Journal on Selected Areas In Communications (2017)

In this paper, we present a centralized method for real-time rainfall estimation using carrier-to-noise power ratio (C/N) measurements from broadband satellite communication networks. The C/N data of both ... [more ▼]

In this paper, we present a centralized method for real-time rainfall estimation using carrier-to-noise power ratio (C/N) measurements from broadband satellite communication networks. The C/N data of both forward link and return link are collected by the gateway station from the user terminals in the broadband satellite communication network and stored in a database. The C/N for such Ka-band scenarios is impaired mainly by the rainfall. Using signal processing and machine learning techniques, we develop an algorithm for real-time rainfall estimation. Extracting relevant features from C/N, we use artificial neural network in order to distinguish the rain events from dry events. We then determine the signal attenuation corresponding to the rain events and examine an empirical relationship between rainfall rate and signal attenuation. Experimental results are promising and prove the high potential of satellite communication links for real environment monitoring, particularly rainfall estimation. [less ▲]

NARCIA: An Automated Tool for Change Impact Analysis in Natural Language Requirements

in 10th Joint Meeting of the European Software Engineering Conference and the ACM SIGSOFT Symposium on the Foundations of Software Engineering, Bergamo 30 August - 4 September 2015 (2015, September)

We present NARCIA, a tool for analyzing the impact of change in natural language requirements. For a given change in a requirements document, NARCIA calculates quantitative scores suggesting how likely ... [more ▼]

We present NARCIA, a tool for analyzing the impact of change in natural language requirements. For a given change in a requirements document, NARCIA calculates quantitative scores suggesting how likely each requirements statement in the document is to be impacted. These scores, computed using Natural Language Processing (NLP), are used for sorting the requirements statements, enabling the user to focus on statements that are most likely to be impacted. To increase the accuracy of change impact analysis, NARCIA provides a mechanism for making explicit the rationale behind changes. NARCIA has been empirically evaluated on two industrial case studies. The results of this evaluation are briefly highlighted. [less ▲]

Automated Checking of Conformance to Requirements Templates using Natural Language Processing

in IEEE Transactions on Software Engineering (2015), 41(10), 944-968

Templates are effective tools for increasing the precision of natural language requirements and for avoiding ambiguities that may arise from the use of unrestricted natural language. When templates are ... [more ▼]

Templates are effective tools for increasing the precision of natural language requirements and for avoiding ambiguities that may arise from the use of unrestricted natural language. When templates are applied, it is important to verify that the requirements are indeed written according to the templates. If done manually, checking conformance to templates is laborious, presenting a particular challenge when the task has to be repeated multiple times in response to changes in the requirements. In this article, using techniques from Natural Language Processing (NLP), we develop an automated approach for checking conformance to templates. Specifically, we present a generalizable method for casting templates into NLP pattern matchers and reflect on our practical experience implementing automated checkers for two well-known templates in the Requirements Engineering community. We report on the application of our approach to four case studies. Our results indicate that: (1) our approach provides a robust and accurate basis for checking conformance to templates; and (2) the effectiveness of our approach is not compromised even when the requirements glossary terms are unknown. This makes our work particularly relevant to practice, as many industrial requirements documents have incomplete glossaries. [less ▲]

Requirement Boilerplates: Transition From Manually-Enforced to Automatically-Verifiable Natural Language Patterns

in Requirements Patterns (RePa), 2014 IEEE 4th International Workshop on (2014, August)

By enforcing predefined linguistic patterns on requirements statements, boilerplates serve as an effective tool for mitigating ambiguities and making Natural Language requirements more amenable to ... [more ▼]

By enforcing predefined linguistic patterns on requirements statements, boilerplates serve as an effective tool for mitigating ambiguities and making Natural Language requirements more amenable to automation. For a boilerplate to be effective, one needs to check whether the boilerplate has been properly applied. This should preferably be done automatically, as manual checking of conformance to a boilerplate can be laborious and error prone. In this paper, we present insights into building an automatic solution for checking conformance to requirement boilerplates using Natural Language Processing (NLP). We present a generalizable method for casting requirement boilerplates into automated NLP pattern matchers and reflect on our practical experience implementing automated checkers for two well-known boilerplates in the RE community. We further highlight the use of NLP for identification of several problematic syntactic constructs in requirements which can lead to ambiguities. [less ▲]

RUBRIC: A Flexible Tool for Automated Checking of Conformance to Requirement Boilerplates

in 9th joint meeting of the European Software Engineering Conference and the ACM SIGSOFT Symposium on the Foundations of Software Engineering (ESEC/FSE 2013) (2013, August)