| 1. |
- Bonafini, F., et al.
(författare)
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Cluster of IoT Sensors for Smart Cities : Impact of the Communication Infrastructure over Computational Performance
- 2019
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Ingår i: Proceedings. - : Institute of Electrical and Electronics Engineers Inc.. - 9781538677131
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Konferensbidrag (refereegranskat)abstract
- The Smart City (SC) paradigm is based on the integration of Information and Communication Technology (ICT) into the urban asset, for the optimal management of the energies and resources. The Internet of Thing (IoT) technology seems the proper solution to achieve this target, thanks to its capability to abstract the object in the real world. The deployment of IoT devices at different level in urban infrastructures is causing the presence of thousands of intelligent devices, large part of them with unused computational capabilities. Such devices could be integrated in a cluster in order to share the unused resources with other devices with limited computational resources. The use of a cluster of IoT Sensors has several benefits, including, but not limited to: high availability, sharing of computational resources, reduced response time with the respect of centralized cloud computing solution. The main bottleneck of this approach is represented by the communication infrastructure, typically based on wireless connection and, thus with a limited available bandwidth. The aim of the work related to this paper is to analyze the impact the communication infrastructure has on computational performance of a cluster of IoT sensors. An experimental set-up for the characterization of the performance of a cluster of low-cost off-the-shelf devices has been described. The experimental validation highlighted as the network infrastructure is loaded only during the data transfer and the maximum network load, with a cluster of ten IoT nodes is approximately 2 Mb/s with the considered benchmark. © 2019 IEEE.
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| 2. |
- Bonafini, F., et al.
(författare)
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Evaluating indoor and outdoor localization services for LoRaWAN in Smart City applications
- 2019
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Ingår i: Proceedings. - : Institute of Electrical and Electronics Engineers Inc.. - 9781728104294 ; , s. 300-305
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Konferensbidrag (refereegranskat)abstract
- Nowadays, wireless technologies penetrate all aspects of our lives. 'Internet of Things' (IoT) and 'Location- Based Services' are the pillars of Smart City concept. The IoT smart objects surrounding us are an integral part of the Internet, thanks to their computational and communication capabilities. In such applications, location information can be exploited in all the layers of the stack, from the application level (e.g., to correctly interpret measurements from sensor nodes deployed on the field), down to the physical level (e.g., for sensing coverage). One of the most viable solutions for Smart City wireless connectivity seems to be the use of long-range, low-power and low-throughput low-power wide area networks (LPWANs). In this work, the authors devise the jointly use of LPWANs with widely-diffused and well-accepted localization techniques, as the Global Positioning Systems (GPS, outdoor) and real-time location systems (RTLS, indoor), for Smart Campus applications. In particular, a LoRaWAN node equipped with both GPS and Ultra Wide Bandbased UWB-RTLS has been developed and tested in real-world scenarios. Experimental results demonstrate the feasibility of the proposed approach; in particular, location errors are in the order of few tens of meters for GPS and in the order of few tens of centimeters for UWB. © 2019 IEEE.
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| 3. |
- Rinaldi, S., et al.
(författare)
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An experimental characterization of time of arrival accuracy for time synchronization of medium voltage smart grid solutions
- 2019
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Ingår i: AMPS 2019 Proceedings. - : Institute of Electrical and Electronics Engineers Inc.. - 9781728100753
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Konferensbidrag (refereegranskat)abstract
- The time synchronization of smart grid devices is a critical feature for the successful application of advanced grid monitoring and control techniques. Synchronization mechanisms based on the accurate estimation of the Time of Arrival (ToA) of network messages-sent over power line cables-are a promising solution to achieve synchronization tasks over distribution lines. In this paper, a chirp-based synchronization technique over the Medium Voltage (MV) grid has been proposed and characterized. Such approach has the benefit of not requiring the installation of a dedicated infrastructure, thanks to the exploitation of power distribution lines for the transmission of time synchronization data. The effectiveness of the approach has been experimentally evaluated on a simplified MV line available in a testing laboratory. Although, the tested chirp has a limited frequency bandwidth (80 kHz), the maximum variation of the ToA estimation is on the order of 3.5 μs, which fulfills the requirements of most smart grid applications. © 2019 IEEE.
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| 4. |
- Rinaldi, S., et al.
(författare)
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Design of a Time Dissemination System Using Chirp Modulation for Medium Voltage Smart Grid Applications
- 2020
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Ingår i: IEEE Transactions on Instrumentation and Measurement. - : Institute of Electrical and Electronics Engineers Inc.. - 0018-9456 .- 1557-9662. ; 69:9, s. 6686-6695
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Tidskriftsartikel (refereegranskat)abstract
- The monitoring and the management of smart grid require an advanced communication infrastructure. The time synchronization is among the most important services such an infrastructure should offer. Several solutions are available to disseminate the time information in a distributed system; for instance, most of the times a global positioning system (GPS) receiver is used to recover accurate time information. However, GPS receivers need a clear view of the sky. Other solutions, like the use of a network-based synchronization mechanism, require a dedicated communication infrastructure, which is not always feasible for economical reason. Thus, the use of the power grid itself to disseminate a time signal is extremely interesting. The aim of this article is to investigate the possibility to distribute a time signal over a medium voltage (MV) grid using a chirp-based modulation. The timing data are coded using IRIG-B time code. Such an approach does not require the installation of a dedicated infrastructure, and it is noninvasive, because the signal is transmitted on a different band with the respect to power line communication (PLC). The effectiveness of the approach has been experimentally evaluated on a test MV line available in a laboratory. Although the tested chirp-based symbol has a limited frequency bandwidth (80 kHz), the jitter in the identification of the start of frame is on the order of 7.5 μ s, fulfilling the requirements of the most smart grid applications. © 1963-2012 IEEE.
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| 5. |
- Rinaldi, S., et al.
(författare)
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Impact of data model on performance of time series database for internet of things applications
- 2019
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Ingår i: Proceedings. - 9781538634608
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Konferensbidrag (refereegranskat)abstract
- The Internet of Things (IoT) paradigm is gaining interest in several application fields, from medical devices to smart building and industrial automation. Such a success is due to the flexibility and interoperability between different application domains: the possibility to vertically share data among applications is the winning point of this technology. IoT sensors installed on the field generate a large amount of data, which have to be stored somewhere for subsequent analysis. Database technologies are experiencing a deep transformation to be able to handle these data streams. The recent trend is a transition from relational to non-relational databases. Among the latter, the Time Series Databases (TSDBs) seem to be the solution for storing large amount of time series data generated by IoT applications. Although these solutions are optimized to handle thousands of parallel data streams from IoT sensors, the performance of data extraction could not be compatible with some applications. The target of the paper is to investigate the impact that different metadata could have over the data extraction performance in TSDBs. A dedicated testing procedure has been configured for evaluating InfluxDB, one of the most effective and widespread TSDBs. The performance analysis, carried out on a specific use case, demonstrated that the database write and read performance can be significantly affected by the used data model, with queries executed on the same data requiring times from hundreds of ms to seconds in the worst cases. © 2019 IEEE.
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| 6. |
- Rinaldi, S., et al.
(författare)
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Software-based time synchronization for integrating power hardware in the loop emulation in IEEE1588 power profile testbed
- 2019
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Ingår i: Proceedings. - : IEEE Computer Society. - 9781538676066
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Konferensbidrag (refereegranskat)abstract
- Modern power systems are becoming more and more complex, in order to handle the growing spread of Renewables and of Electric Vehicle charging stations. The control capability relies on the integration of Information and Communication Technology (ICT), including accurate time distribution mechanisms, such as the IEEE 1588 protocol, to the existing distribution grid infrastructure. The validation of such complex systems can hardly be performed in real environments, for both technical and economic reasons. Power Hardware in the Loop (PHIL) emulation systems have already been demonstrated to be effective for this scope. The design of a testbed for the validation of IEEE 1588 power profile based on PHIL solutions requires the capability to synchronize the time bases of the elements forming the testbed. Commercial PHIL systems often offer proprietary synchronization solutions, but these approaches cannot be applied in the general case. In this paper, a software-based solution, able to time synchronize PHIL with IEEE 1588 devices, has been investigated. Such a solution has the advantage that it does not require dedicated hardware, thus it can be applied to different PHIL systems. The experimental characterization highlights that, using such approach, it is possible to reach a time synchronization with an expanded uncertainty (k=3) of 0.75 μs, more than enough to correctly emulate events on the power grid. © 2019 IEEE.
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