The roadmap toward autonomous mobility is progressing across the industrialized world and Europe is at the forefront, with the recent release of the regulation for the type-approval of the automated driving system of fully automated vehicles. At the same time, the need for more reliable validation methods to ensure safety has become paramount. Real-world road environments open the way to many edge cases, making validation through classic ground tests challenging. The Everything-in-the-Loop approach proposed in the P-CAR project aims to fill the gap. To prove its capabilities, we have selected the Intelligent Speed Assistance system as a representative use case among the possible functionalities of a connected and automated vehicle. The choice is motivated by its reliance on advanced technologies, including connectivity, digital maps, positioning, and on-board sensing. The paper describes the proposed approach and the main aspects of the implementation. Then, it focuses on the validation process implemented by the P-CAR laboratory, whose outcomes represent a successful compliance test.

This paper considers channel modeling and evaluation of second-order outage statistics of mixed radio frequency/free space optical (RF/FSO) relay systems over mixed turbulence induced fading (TIF) and non-turbulence induced fading (non-TIF) channels. The derived statistics are directly related to the performance measures. In particular, we derive fast computing closed form expressions for relevant statistics such as cumulative-distribution-function (CDF), level-crossing-rate (LCR), and average-fade-duration (AFD). Approximation through Laplace integration of the products of random processes modeled as Gamma-Gamma (G-G) and Nakagami-m (N-m) are exploited. The proposed framework is then applied to two different scenarios for vehicular networks: i) I2I (infrastructure-to-infrastructure) direct communications enabled by FSO link, ii) V2V (vehicle-to-vehicle) communications enabled by RF/FSO/RF AaF (amplify-and-forward) relay link. Moreover, we provide numerical results for various settings of RF/FSO system model parameters.

Vehicular communication technologies are the enabling factor for development of smart mobility applications. Current solutions proposed by standard organizations support short and medium range communications, based on IEEE 802.11p for delay-sensitive applications and on cellular networking for integrated data management over large areas. This distinction could be overcome by the unifying paradigm of 5G. Mobility services require a continuous exchange of awareness messages among vehicles and road infrastructure elements, mainly for safety applications. Whatever communication technology is used, a basic requirement for the effectiveness and reliability of safety applications is the radio channel availability for dissemination of information among network elements. This paper describes our ongoing activities of study, analysis, and experimentation about channel congestion evaluation and control strategies, relying both on real devices and simulation environments. The proposed framework of tools and current activities can provide a good base for modeling complex urban scenarios in a perfect context for testing, like the city of L'Aquila, that aims at being reconceived as a modern smart city, and has been selected for 5G experimentation.

Cooperative Intelligent Transport System (C-ITS) applications require a continuous exchange of information between road users and roadside infrastructures. In this regard, distributed consensus algorithms can play an essential role in the definition of the information exchange rules between an ITS station and its neighbors. Although the consensus approach for networked systems is well-established, the efficiency of consensus methods under real-world vehicular communication constraints is largely unknown. This paper provides an ITS standard-compliant framework for analysis of consensus algorithms in vehicular networks with an emphasis on the role of robustness to changes in network topology in highly dynamic and dense environments. Our simulations reveal that in regular traffic conditions, the implemented consensus algorithm is able to achieve good performances in terms of both convergence time and needed consensus iterations. However, numerical results demonstrate that under dense and high- mobility traffic conditions the frequent exchange of large amounts of range information increases the Channel Busy Ratio (CBR) of the vehicular network and reduces the effectiveness of the algorithm as well.

Wireless Mesh Networks (WMNs) propose themselves as a network architecture suitable for a wide range of applications, very versatile, rather cheap and easy to deploy. The capability of clients to forward information among each other, thus implementing a Hybrid WMN, allows to extend the network coverage and makes them suitable for the information delivery in Intelligent Transportation Systems and in Public Safety applications. The increase of the network size, i.e. of the number of nodes and of available access points for the clients, and its division into routing domains with different characteristics, raises the problem of different paths for upstream and downstream flows in the same conversation. Such routing asymmetry often leads to a waste of the radio resources shared among clients and, consequently, to reduction of network performances. In this paper we propose a strategy for an efficient interconnection of the client network with the backbone, in order to minimize the asymmetry of paths. The presented solution does not depend on a specific routing protocol and involves only the boundary devices, thus requiring a low effort for its implementation. A peculiar feature of our work is experimental validation through a testbed consisting of real world devices; the obtained results show an improvement in network performances for the involved nodes, evaluated in terms of network delay and network throughput.

The analysis of a network path between a source and a destination using traditional networking tools like ping and traceroute, does not provide informations about the return path. In the absence of those informations, malfunctions and faults can not be managed with adequate effectiveness. In this paper we propose two techniques to perform network path discovery in production networks, without the necessity of a centralized network monitoring system. The first solution is suitable for IPv6 networks, while the second one is suitable in both IPv4 and IPv6 contexts. In order to pursue troubleshooting efficiency and because of possible restrictive policies, the path discovery is triggered by acting only on a single device (from now on called the Discovery Router), without the need of retrieving informations on multiple network equipments. The IPv6-only approach relies on the use of the Hop-by-Hop Option Extension Header without the definition of new options; the second proposed approach aims at the activation on the target device of a traceroute back through the discovery router, then combining the capabilities of SNMP and TFTP. Therefore, it is possible to identify the path between any two routers, for both directions, in a traceroute-like format.

Moving from the need for a simple and versatile method for outage computation in various contexts of interest in wireless communications, in this paper we propose a lognormal approximation for the linear combination of a set of lognormal random variables (RV) with one-sided random weights. The approximation is based on a generalization of the well known moment matching approximation (MMA) for the sum of lognormal RVs, and it allows quite simple handling of the power sum of interfering signals even in rather complicated scenarios. Specifically, composite multiplicative channel models with unequal parameters can be handled, and generic (unequal) correlation patterns for some channel components can be handled with reference to any pair of signals. At this stage of the computation, only moments of the random weights are required. The probability density function of the random weight for the useful signal component may be required in computing outage probability, and numerical methods may be only required to solve a single integral at this second stage. The suitability of the approximation is examined by evaluating outage performance for various values of system parameters in the context of interest of composite Nakagami-lognormal channels in reuse-based systems

Moving from the need for a simple and versatile method for outage computation in various contexts of interest in wireless communications, in this paper we propose a lognormal approximation for the linear combination of a set of lognormal random variables (RV) with one-sided random weights. The approximation is based on a generalization of the well known moment matching approximation (MMA) for the sum of lognormal RVs, and it allows quite simple handling of the power sum of interfering signals even in rather complicated scenarios. Specifically, composite multiplicative channel models with unequal parameters can be handled, and generic (unequal) correlation patterns for some channel components can be handled with reference to any pair of signals. At this stage of the computation, only moments of the random weights are required. The probability density function of the random weight for the useful signal component may be required in computing outage probability, and numerical methods may be only required to solve a single integral at this second stage. The suitability of the approximation is examined by evaluating outage performance for various values of system parameters in some contexts of interest, namely spread spectrum systems and typical reuse-based systems with composite Rayleigh-lognormal and Nakagami-lognormal channels.

The DAta and Video Interactive Distribution (DAVID) satellite mission belongs to the small missions for science and technology programme of the Italian Space Agency and is intended to pioneer the use of W-band for an experimental collection of a high volume of data and its forwarding, through Ka-band links, to the Internet. The satellite launch is envisaged in 2004. The system presents various technological innovations and will also collect data from very remote scientific laboratories in Antarctica, allowing also remote control of the experiments.

A novel methodology is proposed for computing the outage probability in mobile radio systems in the presence of log-normal shadowing. A relevant feature is that the proposed analysis assumes a general correlation for any pair of links. Various approaches are considered to compute the statistics of user signal-to-interference ratio (SIR), namely Schwartz and Yeh's method, Wilkinson's method, and Fenton's method. By a simple reformulation of the problem, these methods can be used to calculate in a straightforward way the parameters of the SIR. The accuracy of the methods is checked in a number of situations of interest. Moreover, when the same correlation is assigned to any pair of links, the novel analysis is more accurate than previously proposed approaches.

In this paper, the problem of computing cochannel interference statistics in signal strength measurements in mobile radio systems is presented. In a cellular environment with cross-correlated log-normal shadowings, extensions of Wilkinson's method and Schwartz and Yeh's (1982) method are proposed for evaluating the statistics of differences between signal strengths that a mobile terminal measures on the links to any pair of base stations in the presence of cochannel interferers. The derived statistics are then used in the performance analysis of relative signal strength handover algorithms. Results provided by the two methods are compared with simulation results, in order to assess their accuracy, and computational issues are addressed. From numerical results, it is also seen that handover algorithm performance has a noticeable dependence on both cross correlation among shadow fadings and the interference level. Finally, it is seen that previous approaches to derive cochannel interference statistics in the presence of log-normal shadowing can be obtained as particular cases.