Search results for " telecomunicazioni"

An Improved IEEE 802.11 Protocol for Reliable Data Transmission in Power Distribution Fault Diagnosis

2010

A high level of power quality in distribution networks is obtained by means of a diagnostic software, that on-line assesses the status of the network, by elaborating the measured data. An efficient telecommunication system is thus necessary. Upon occurrence of a fault the reliability of the distribution system depends on the security of the timely protective and restorative actions on the network. In this paper, after a brief examination of the diagnostic method, the telecommunication system is examined. For this purpose, the WiFi telecommunication system has been considered the most suitable due to its economy, although it is not adequately reliable for how it is managed by the IEEE 802.11…

Revealing Transmit Diversity Mechanisms in Commercial IEEE 802.11 Cards

2008

Service differentiation in WLAN has been traditionally faced at the MAC layer. However, some PHY layer parameters, such as the transmission power, the antenna, and the modulation/coding scheme, have a deep impact on network performance. Since the criterion for selecting these parameters is left to the vendor specific implementations, the performance spread of most experimental results about 802.11 WLAN could be affected by vendor proprietary schemes. The focus of this paper is an experimental analysis of the undisclosed antenna diversity mechanisms employed by some widely used cards (namely, the Atheros and Intel based cards), and a thorough understanding of the optimization goals which gui…

An Embedded System for the integration of a Combined Photovoltaic Solar (CPS) system into a ZigBee Home Area Network

2011

In this paper is reported the design and implementation of an electronic system capable of communicating over a standard ZigBee network in order to let a residential gateway collector, named agent, gain access to the parameters of a Combined Photovoltaic and Solar thermal (CPS) plant, thus realizing a networked energy production appliance . The system is made of three parts: a PV metering device, a boiler metering device also capable of controlling a heating resistor embedded within the boiler tank, and a data collector acting as a ZigBee node. The data collector device periodically retrieves the following parameters from the metering devices: instantaneous photovoltaic power production, ac…

The FP7 BeyWatch European scientific project: general features and design criteria of the Combined Photovoltaic Solar (CPS) system within the BEYWATC…

2011

This paper includes the general features and design criteria of a combined photovoltaic solar system (CPS) and its allocation within the entire architecture of the BeyWatch system. The CPS main functionalities and characteristics, the description of the CPS main components and the CPS electronic control and monitoring subsystem, together with the description of the Firmware design and communication protocols are here reported. The Combined Photovoltaic and Solar system (CPS) is a Renewable Energy system that produces thermal and electrical energy and the design has been based on a modular approach.

End-to-end Bandwidth Estimation in the Wide Internet

2010

Realizing airtime allocations in multi-hop Wi-Fi networks: A stability and convergence study with testbed evaluation

2019

Abstract REACT is a distributed resource allocation protocol used to negotiate a max–min allocation of airtime for multi-hop ad hoc wireless networks. Two approaches are proposed for a node to realize its REACT allocation in a contention-based MAC protocol. This is achieved by tuning its contention window to a value that corresponds to its allocation. Only a change in the allocation, due to a change in local traffic requirements or local network views, results in re-tuning. The approaches for tuning are implemented in commercial Wi-Fi devices and their stability and convergence are studied experimentally in the w-iLab.t wireless network testbed. These properties are also studied analyticall…

A Survey on LoRa for Smart Agriculture: Current Trends and Future Perspectives

2023

This paper provides a survey on the adoption of LoRa in the agricultural field, and reviews state-of-the-art solutions for Smart Agriculture, analyzing the potential of this technology in different infield applications. In particular, we consider four reference scenarios, namely irrigation systems, plantation and crop monitoring, tree monitoring, and livestock monitoring, which exhibit heterogeneous requirements in terms of network bandwidth, density, sensors’ complexity, and energy demand, as well as latency in the decision process. We discuss how LoRa-based solutions can work in these scenarios, analyzing their scalability, interoperability, network architecture, and energy-efficiency. Fi…

The quest for bandwidth estimation techniques for large-scale distributed systems

2010

In recent years the research community has developed many techniques to estimate the end-to-end available bandwidth of an Internet path. This important metric can be potentially exploited to optimize the performance of several distributed systems and, even, to improve the effectiveness of the congestion control mechanism of TCP. Thus, it has been suggested that some existing estimation techniques could be used for this purpose. However, existing tools were not designed for large-scale deployments and were mostly validated in controlled settings, considering only one measurement running at a time. In this paper, we argue that current tools, while offering good estimates when used alone, migh…

Large-Scale Available Bandwidth Measurements: Interference in Current Techniques

2011

The end-to-end available bandwidth of an Internet path is a desirable information that can be exploited to optimize system performance. Several tools have been proposed in the past to estimate it. However, existing measurement techniques were not designed for large-scale deployments. In this paper we show that current tools do not properly work where multiple probing processes share a portion of a path. We provide experimental evidence to quantify the impact of mutual interference between measurements. We further analyze the characteristics of popular tools, quantifying (i) the impact of mutual interference, (ii) the total overhead imposed to the network and (iii) the intrusiveness of the m…

A Technical Approach to the Energy Blockchain in Microgrids

2018

The present paper considers some technical issues related to the “energy blockchain” paradigm applied to microgrids. In particular, what appears from the study is that the superposition of energy transactions in a microgrid creates a variation of the power losses in all the branches of the microgrid. Traditional power losses allocation in distribution systems takes into account only generators while, in this paper, a real-time attribution of power losses to each transaction involving one generator and one load node is done by defining some suitable indices. Besides, the presence of P–V nodes increases the level of reactive flows and provides a more complex technical perspective. For this re…