Geographic Admission Control for Vehicle Area Networks

Abstract-A vehicle area network (VAN) is a local area network deployed onboard a moving vehicle, e.g., a train, bus, or a private car, to provide high-speed Internet access to the passengers. A VAN may face temporary network disconnection when the vehicle passes through challenging radio environments, e.g., deep tunnels. Such disconnections disrupt the ongoing network services causing passenger dissatisfaction. Given that tunnel locations are known, we propose to use geographical knowledge in the admission control function of the VAN to reduce the probability of service disruption. A geographic admission controller (GAC) rejects a new call request based on the vehicle's current location if it can be determined that the vehicle would enter a tunnel within a short period of time. By rejecting a new call prior to entering a tunnel, GAC reduces the probability of an admitted call to be disrupted, but it does so at the expense of increasing probability that a new request would be blocked. For a quantitative investigation of the trade-off between these two important probabilities, we propose a 2-D Markov Chain model. Using the model, we derive both probabilities as a function of the time interval from the moment the GAC starts rejecting new requests until the vehicle actually enters the tunnel. This time interval is a configurable parameter which controls both probabilities. The model is validated using simulation. Our model reveals that the disruption probability can be reduced quadratically with a linear increase in the blocking probability

Stuck in Traffic (SiT) Attacks: A Framework for Identifying Stealthy Attacks that Cause Traffic Congestion

Recent advances in wireless technologies have enabled many new applications in Intelligent Transportation Systems (ITS) such as collision avoidance, cooperative driving, congestion avoidance, and traffic optimization. Due to the vulnerable nature of wireless communication against interference and intentional jamming, ITS face new challenges to ensure the reliability and the safety of the overall system. In this paper, we expose a class of stealthy attacks -- Stuck in Traffic (SiT) attacks -- that aim to cause congestion by exploiting how drivers make decisions based on smart traffic signs. An attacker mounting a SiT attack solves a Markov Decision Process problem to find optimal/suboptimal attack policies in which he/she interferes with a well-chosen subset of signals that are based on the state of the system. We apply Approximate Policy Iteration (API) algorithms to derive potent attack policies. We evaluate their performance on a number of systems and compare them to other attack policies including random, myopic and DoS attack policies. The generated policies, albeit suboptimal, are shown to significantly outperform other attack policies as they maximize the expected cumulative reward from the standpoint of the attacker

MIRAI Architecture for Heterogeneous Network

One of the keywords that describe next-generation wireless communications is "seamless." As part of the e-Japan Plan promoted by the Japanese Government, the Multimedia Integrated Network by Radio Access Innovation project has as its goal the development of new technologies to enable seamless integration of various wireless access systems for practical use by 2005. This article describes a heterogeneous network architecture including a common tool, a common platform, and a common access. In particular, software-defined radio technologies are used to develop a multiservice user terminal to access different wireless networks. The common platform for various wireless networks is based on a wireless-supporting IPv6 network. A basic access network, separated from other wireless access networks, is used as a means for wireless system discovery, signaling, and paging. A proof-of-concept experimental demonstration system is available

Commercially-and-socially-oriented postal services

The main goal of this paper is show how postal communication service, which has been strengthened with the technology development in the last century, is nowadays commercially-and-socially-oriented very important for human life. Furthermore, I will prove how postal service becomes overwhelming for some not communicated, far and isolated geographic areas in developing countries, to get in touch with people and businesses from around the world. Over one hundred of Postal Operators were interviewed in Peru between 2004 and 2006, around 25% of total, which said that distance and security are not longer considered as a challenge for postal services thanks to new Information and Communication Technologies (ICT) and Internet; which in turn has facilitated (i) social communication, (ii) financial services, (iii) e-commerce and (iv) international business, bolstered by postal services. This last issue can be proved with high correlation statistics between the international postal (and courier) shipments and the exportation of non traditional goods, as well as importation of goods in Peru; moreover, some international remittances from around the world are making through the postal transferences. Consequently, Peruvian authorities, especially from the Ministry of Transport and Communications, must consider the importance of postal and/or courier services in the elaboration of public policies to pursuit the socioeconomic development.Postal services; financial postal; international business; communication; e-commerce;

Efficient channel allocation and medium access organization algorithms for vehicular networking

Due to the limited bandwidth available for Vehicular Ad-hoc Networks (VANETs), organizing the wireless channel access to efficiently use the bandwidth is one of the main challenges in VANET. In this dissertation, we focus on channel allocation and media access organization for Vehicle-to-Roadside Units (V2R) and Vehicle-to-Vehicle (V2V) communications. An efficient channel allocation algorithm for Roadside Unit (RSU) access is proposed. The goal of the algorithm is to increase system throughput by admitting more tasks (vehicles) and at the same time reduce the risk of the admitted tasks. The algorithm admits the new requests only when their requirements can be fulfilled and all in-session tasks\u27 requirements are also guaranteed. The algorithm calculates the expected task finish time for the tasks, but allocates a virtual transmission plan for the tasks as they progress toward the edges of the RSU range. For V2V mode, we propose an efficient medium access organization method based on VANETs\u27 clustering schemes. In order to make this method efficient in rapid topology change environment like VANET, it\u27s important to make the network topology less dynamic by forming local strongly connected clustering structure, which leads to a stable network topology on the global scale. We propose an efficient cluster formation algorithm that takes vehicles\u27 mobility into account for cluster formation. The results of the proposed methods show that the wireless channel utilization and the network stability are significantly improved compared to the existing methods

Building Knowledge Stocks: The Role of State Higher-Education Policies

A variety of studies provide evidence that the stock of college-educated labor has fundamental effects on state and local economies through its association with wages, economic growth, personal incomes, and tax revenues. As a result, policymakers in many states try to increase the percentage of the state’s population (or workforce) that has a college degree through the use of various higher-education policies that have the potential to influence the supply side of the labor market. This paper reviews evidence on the effectiveness of these policies in achieving that goal. I discuss several types of policies related to the finance and production of undergraduate education within a state, including expansions in degree production and scholarships to encourage attendance at in-state colleges. The evidence suggests that these policies can affect the stock of college-educated labor within a state, but that effect is limited by the mobility of college graduates across state boundaries. I also discuss location-contingent financial aid, adjustments to the composition of enrollment by residency or by field of study, and internships with state-based employers. More research is needed to identify the causal effects of these policies on the behavior of students and to sort out the responses by students and institutions to changes in state policies

Health, wealth, and air pollution: advancing theory and methods.

The effects of both ambient air pollution and socioeconomic position (SEP) on health are well documented. A limited number of recent studies suggest that SEP may itself play a role in the epidemiology of disease and death associated with exposure to air pollution. Together with evidence that poor and working-class communities are often more exposed to air pollution, these studies have stimulated discussion among scientists, policy makers, and the public about the differential distribution of the health impacts from air pollution. Science and public policy would benefit from additional research that integrates the theory and practice from both air pollution and social epidemiologies to gain a better understanding of this issue. In this article we aim to promote such research by introducing readers to methodologic and conceptual approaches in the fields of air pollution and social epidemiology; by proposing theories and hypotheses about how air pollution and socioeconomic factors may interact to influence health, drawing on studies conducted worldwide; by discussing methodologic issues in the design and analysis of studies to determine whether health effects of exposure to ambient air pollution are modified by SEP; and by proposing specific steps that will advance knowledge in this field, fill information gaps, and apply research results to improve public health in collaboration with affected communities