10,386 research outputs found
Long-Range Connections in Transportation Networks
Since its recent introduction, the small-world effect has been identified in
several important real-world systems. Frequently, it is a consequence of the
existence of a few long-range connections, which dominate the original regular
structure of the systems and implies each node to become accessible from other
nodes after a small number of steps, typically of order .
However, this effect has been observed in pure-topological networks, where the
nodes have no spatial coordinates. In this paper, we present an alalogue of
small-world effect observed in real-world transportation networks, where the
nodes are embeded in a hree-dimensional space. Using the multidimensional
scaling method, we demonstrate how the addition of a few long-range connections
can suubstantially reduce the travel time in transportation systems. Also, we
investigated the importance of long-range connections when the systems are
under an attack process. Our findings are illustrated for two real-world
systems, namely the London urban network (streets and underground) and the US
highways network enhanced by some of the main US airlines routes
Fine-Grained Reliability for V2V Communications around Suburban and Urban Intersections
Safe transportation is a key use-case of the 5G/LTE Rel.15+ communications,
where an end-to-end reliability of 0.99999 is expected for a vehicle-to-vehicle
(V2V) transmission distance of 100-200 m. Since communications reliability is
related to road-safety, it is crucial to verify the fulfillment of the
performance, especially for accident-prone areas such as intersections. We
derive closed-form expressions for the V2V transmission reliability near
suburban corners and urban intersections over finite interference regions. The
analysis is based on plausible street configurations, traffic scenarios, and
empirically-supported channel propagation. We show the means by which the
performance metric can serve as a preliminary design tool to meet a target
reliability. We then apply meta distribution concepts to provide a careful
dissection of V2V communications reliability. Contrary to existing work on
infinite roads, when we consider finite road segments for practical deployment,
fine-grained reliability per realization exhibits bimodal behavior. Either
performance for a certain vehicular traffic scenario is very reliable or
extremely unreliable, but nowhere in relatively proximity to the average
performance. In other words, standard SINR-based average performance metrics
are analytically accurate but can be insufficient from a practical viewpoint.
Investigating other safety-critical point process networks at the meta
distribution-level may reveal similar discrepancies.Comment: 27 pages, 6 figures, submitted to IEEE Transactions on Wireless
Communication
A survey of localization in wireless sensor network
Localization is one of the key techniques in wireless sensor network. The location estimation methods can be classified into target/source localization and node self-localization. In target localization, we mainly introduce the energy-based method. Then we investigate the node self-localization methods. Since the widespread adoption of the wireless sensor network, the localization methods are different in various applications. And there are several challenges in some special scenarios. In this paper, we present a comprehensive survey of these challenges: localization in non-line-of-sight, node selection criteria for localization in energy-constrained network, scheduling the sensor node to optimize the tradeoff between localization performance and energy consumption, cooperative node localization, and localization algorithm in heterogeneous network. Finally, we introduce the evaluation criteria for localization in wireless sensor network
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