1,720,980 research outputs found
Studio dei modi superficiali in guide d'onda a cavita' antirisonante con core rettangolare cavo
No full text
Metodo per l'interazione tra almeno un terminale ed una pluralità di reti di telecomunicazione
No full textMultihop IEEE 802.15.4 wireless networks with finite node buffers: Markov chain-based analysis
No full textIn this paper, we propose a Markov chain-based analytical framework for modeling the behavior of the medium access control (MAC) protocol in IEEE 802.15.4 wireless sensor networks. Two scenarios are of interest. First, we consider networks where the sensor nodes communicate directly to the network coordinator. Then, we consider scenarios where sensor nodes communicate to the coordinator through an intermediate relay node, which forwards the packets received from the sources (i.e., the sensors). In both scenarios, no acknowledgment messages are used to confirm successful data packet deliveries, and communications are beaconed (i.e., they rely on synchronization packets denoted as “beacons”). In all considered scenarios, our focus is on networks where the relay and the source nodes have finite queues (denoted as buffers) to store data packets. Network performace is characterized in terms of aggregate network throughput and packet delivery delay. Our results show a very good agreement between the proposed analytical model and realistic ns-2 simulation results. In particular, the impact of the buffer size is accurately taken into account in our model
Wireless Communications for Vehicular Ad-Hoc Networks
No full textIn this chapter, we present a novel theoretical framework suitable for analytical performance evaluation of a family of multihop broadcast protocols. The framework allows to derive several average performance metrics, including reliability, latency, and efficiency, and it is targeted to Vehicular Ad-hoc NETworks (VANETs) applications based on an underlying IEEE 802.11 protocol. It builds on the assumption that the positions of the nodes of a VANET can be statistically modeled as Poisson points. However, the proposed approach holds for any spatial vehicle distribution with constant average distance between consecutive vehicles. In this chapter, the proposed analytical framework is applied to the class of probabilistic broadcast multihop protocols with silencing, but can be generalized to non-probabilistic protocols as well. More specifically, this chapter considers a few broadcast protocols with silencing, differing for the probability assignment function. The effectiveness of the proposed analytical approach is assessed by means of numerical simulations in a highway-like scenario
Advanced technologies for intelligent transportation systems
No full textThis book focuses on emerging technologies in the field of Intelligent Transportation Systems (ITSs) namely efficient information dissemination between vehicles, infrastructures, pedestrians and public transportation systems. It covers the state-of-the-art of Vehicular Ad-hoc Networks (VANETs), with centralized and decentralized (Peer-to-Peer) communication architectures, considering several application scenarios. With a detailed treatment of emerging communication paradigms, including cross networking and distributed algorithms. Unlike most of the existing books, this book presents a multi-layer overview of information dissemination systems, from lower layers (MAC) to high layers (applications). All those aspects are investigated considering the use of mobile devices, such as smartphones/tablets and embedded systems, i.e. technologies that during last years completely changed the current market, the user expectations, and communication networks. The presented networking paradigms are supported and validated by means of extensive simulative analysis and real field deployments in different application scenarios. This book represents a reference for professional technologist, postgraduates and researchers in the area of Intelligent Transportation Systems (ITSs), wireless communication and distributed systems.
Introduction
No full textThe aim of this chapter is to illustrate the principles and challenges of Intelligent Transportation Systems (ITSs), with particular emphasis on traffic information technologies. We also present a standardization history, considering the issues that are still open
Advanced Technologies for Intelligent Transportation Systems
No full textThis book focuses on emerging technologies in the field of Intelligent Transportation Systems (ITSs) namely efficient information dissemination between vehicles, infrastructures, pedestrians and public transportation systems. It covers the state-of-the-art of Vehicular Ad-hoc Networks (VANETs), with centralized and decentralized (Peer-to-Peer) communication architectures, considering several application scenarios. With a detailed treatment of emerging communication paradigms, including cross networking and distributed algorithms. Unlike most of the existing books, this book presents a multi-layer overview of information dissemination systems, from lower layers (MAC) to high layers (applications). All those aspects are investigated considering the use of mobile devices, such as smartphones/tablets and embedded systems, i.e. technologies that during last years completely changed the current market, the user expectations, and communication networks. The presented networking paradigms are supported and validated by means of extensive simulative analysis and real field deployments in different application scenarios.
This book represents a reference for professional technologist, postgraduates and researchers in the area of Intelligent Transportation Systems (ITSs), wireless communication and distributed systems
Hierarchical Architecture for Cross Layer ITS Communications
No full textIn this chapter, we present an innovative approach for effective cross-network information dissemination, with applications to vehicular ad hoc networks (VANETs). The proposed approach, denoted as "Cross-Network Effective Traffic Alert Dissemination" (X-NETAD), leverages on the spontaneous formation of local WiFi (IEEE 802.11b) VANETs, with direct connections between neighboring vehicles, in order to disseminate, very quickly and inexpensively, traffic alerts received from the cellular network. The proposed communication architecture has been implemented on Android smartphones. The obtained experimental results show that an effective cross-network information dissemination service can entirely rely on smartphone-based communications. This paves the way to future Internet architectures, where vehicles will play a key role as information destinations and sources
- …
