238,086 research outputs found

    Context-aware Peer-to-Peer and Cooperative Positioning

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    Peer-to-peer and cooperative positioning represent one of the major evolutions for mass-market positioning, bringing together capabilities of Satellite Navigation and Communication Systems. It is well known that smartphones already provide user position leveraging both GNSS and information collected through the communication network (e.g., Assisted-GNSS). However, exploiting the exchange of information among close users can attain further benefits. In this paper, we deal with such an approach and show that sharing information on the environmental conditions that characterize the reception of satellite signals can be effectively exploited to improve the accuracy and availability of user positioning. This approach extends the positioning service to indoor environments and, in general, to any scenario where full visibility of the satellite constellation cannot be grante

    Successful Approaches for the Use of Unmanned Aerial Systems by Surface Transportation Agencies

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    The past decade has seen ever-increasing attention and resources dedicated to the application and operation of unmanned aircraft systems (UASs). Beginning with issuance of special airworthiness certificates in the experimental category for unmanned aircraft in 2007, up to the Federal Aviation Administration’s (FAA’s) Modernization and Reform Act of 2012 and creation of Title 14 Code of Federal Regulations (CFR) §107 and §101, the complexity and breadth of applications for UAS technology have flourished. Recognizing the interest and potential benefits to the surface transportation community the National Cooperative Highway Research Program (NCHRP) commissioned Scan 17-01 to accelerate beneficial innovation by facilitating information sharing and technology exchange among the states and other transportation agencies. Results from a desk scan, amplifying questions, and a peer exchange workshop produced conclusions and recommendations in seven topic areas for transportation agencies to consider when getting started using a UAS

    Decentralized Control of Cooperative Systems: Categorization and Complexity Analysis

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    Decentralized control of cooperative systems captures the operation of a group of decision makers that share a single global objective. The difficulty in solving optimally such problems arises when the agents lack full observability of the global state of the system when they operate. The general problem has been shown to be NEXP-complete. In this paper, we identify classes of decentralized control problems whose complexity ranges between NEXP and P. In particular, we study problems characterized by independent transitions, independent observations, and goal-oriented objective functions. Two algorithms are shown to solve optimally useful classes of goal-oriented decentralized processes in polynomial time. This paper also studies information sharing among the decision-makers, which can improve their performance. We distinguish between three ways in which agents can exchange information: indirect communication, direct communication and sharing state features that are not controlled by the agents. Our analysis shows that for every class of problems we consider, introducing direct or indirect communication does not change the worst-case complexity. The results provide a better understanding of the complexity of decentralized control problems that arise in practice and facilitate the development of planning algorithms for these problems

    Signalling Design in Sensor-Assisted mmWave Communications for Cooperative Driving

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    Millimeter-Wave (mmWave) Vehicle-To-Vehicle (V2V) communications are a key enabler for connected and automated vehicles, as they support the low-latency exchange of control signals and high-resolution imaging data for maneuvering coordination. The employment of mmWave V2V communications calls for Beam Alignment and Tracking (BAT) procedures to ensure that the antenna beams are properly steered during motion. The conventional beam sweeping approach is known to be unsuited for the high vehicular mobility and its large overhead reduces transmission efficiency. A promising solution to reduce BAT signalling foresees the integration of V2V communication systems with on-board vehicle sensors. We focus on a cooperative sensor-assisted architecture for mmWave V2V communications in line of sight, where vehicles exchange the estimate of antenna position and its uncertainty to compute the optimal beam direction and dimension. We analyze and compare different signalling strategies for sharing the information on antenna estimate, evaluating the tradeoff between signalling overhead and performance loss for different position and uncertainty encoding strategies. Main attention is given to differential quantization on both the antenna position and uncertainty. Analyses over realistic urban mobility trajectories suggest that differential approaches introduce a negligible performance loss while significantly reducing the BAT signalling communication overhead
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