760 research outputs found

    Study on QoS support in 802.11e-based multi-hop vehicular wireless ad hoc networks

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    Multimedia communications over vehicular ad hoc networks (VANET) will play an important role in the future intelligent transport system (ITS). QoS support for VANET therefore becomes an essential problem. In this paper, we first study the QoS performance in multi-hop VANET by using the standard IEEE 802.11e EDCA MAC and our proposed triple-constraint QoS routing protocol, Delay-Reliability-Hop (DeReHQ). In particular, we evaluate the DeReHQ protocol together with EDCA in highway and urban areas. Simulation results show that end-to-end delay performance can sometimes be achieved when both 802.11e EDCA and DeReHQ extended AODV are used. However, further studies on cross-layer optimization for QoS support in multi-hop environment are required

    Sun, Sea, and Sand: U.S. Militarism and Tourism in the Philippines

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    This study explores the complex relationship between U.S. militarism and tourism in the Philippines. The tourism perspective that is prominent throughout challenges the equality of the military partnership between the U.S. and the Philippines. This study analyses the history of the U.S. military presence in the Philippines, starting with the colonial era at the turn of the twentieth century. Assessing infrastructure—its past and ongoing development—reveals itself as a significant connection between militarism and tourism—mobility. Ultimately, this study of the relationship between U.S. militarism and tourism provides a better understanding of the future impacts of the Enhanced Defense Cooperation Agreement—a 2016 bilateral agreement—in the Philippines

    Internet Access and QoS in Ad Hoc Networks

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    It is likely that the increased popularity of wireless local area networks (WLANs) together with the continuous technological advances in wireless communication, also increase the interest for ad hoc networks. An ad hoc network is a wireless, autonomous, infrastructure-less network composed of stations that communicate with each other directly in a peer-to-peer fashion. When discussing mobile ad hoc networks (MANETs), we often refer to an ad hoc network where the stations cooperate in forwarding packets on behalf of each other to allow communication beyond their transmission range over multi-hop paths. In order to realize the practical benefits of ad hoc networks, two challenges (among others) need to be considered: distributed quality of service (QoS) guarantees and multi-hop Internet access. This thesis presents conceivable solutions to both of these problems. The first two papers focus on the network layer and consider the provisioning of Internet access to ad hoc networks whereas the last two papers focus on the data link layer and investigate the provisioning of QoS to ad hoc networks. The first paper studies the interconnection between a MANET and the Internet. In addition, it evaluates three approaches for gateway discovery, which can be initiated by the gateway (proactive method), by the mobile station (reactive method) or by mixing these two approaches (hybrid method). The second paper also studies Internet access for MANETs, but with focus on micro mobility, i.e. mobile stations moving from one gateway to another. In particular, it evaluates a solution that allows mobile stations to access the Internet and roam from gateway to gateway. The third paper, gives an overview of the medium access mechanisms in IEEE 802.11 and their QoS limitations. Moreover, it proposes an enhancement to the contention-free medium access mechanism of IEEE 802.11e to provide QoS guarantees in WLANs operating in ad hoc network configuration. The fourth paper continues the work from the third paper by enhancing the scheme and dealing with the problems that occur due to hidden stations. Furthermore, it discusses how to deal with the problems that occur when moving from single-hop ad hoc networks (i.e. WLANs in ad hoc network configuration) to multi-hop ad hoc networks

    Final report on the evaluation of RRM/CRRM algorithms

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    Deliverable public del projecte EVERESTThis deliverable provides a definition and a complete evaluation of the RRM/CRRM algorithms selected in D11 and D15, and evolved and refined on an iterative process. The evaluation will be carried out by means of simulations using the simulators provided at D07, and D14.Preprin

    An Intelligent Management System for Hybrid Network between Visible Light Communication and Radio Frequency

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    This thesis investigates the challenges and potential solutions associated with hybrid Visible Light Communication (VLC) and Radio Frequency (RF) systems for indoor network environments. The rapid development of VLC technology, characterized by its high data rates, energy efficiency, and inherent security features, offers promising opportunities to complement RF networks in providing seamless connectivity and improved performance. However, integrating VLC and RF technologies effectively requires addressing a range of research and engineering challenges, including network coexistence, handover mechanisms, resource allocation, localization, and standardization.We begin by conducting a comprehensive literature review encompassing existing research, technologies, and solutions related to hybrid VLC/RF architectures, handover management, indoor localization techniques, and the challenges faced by these systems. This background provides a solid foundation for understanding the current state-of-the-art and identifying research gaps in the field of hybrid VLC/RF networks.Next, we propose a novel hybrid network architecture that integrates VLC and RF communication systems to enhance their strengths while mitigating their weaknesses. We discuss various types of hybrid VLC/RF architectures found in the literature and present our proposed design, which addresses the identified challenges through innovative strategies and mechanisms.To improve system performance in our hybrid system, we develop an enhanced priority feedback channel that optimizes the traffic priority based on user preferences and network conditions. This approach minimizes service disruptions, reduces latency, and maintains user Quality of Experience (QoE)\nomenclature{QoE}{Quality of Experience}.Furthermore, we introduce a novel intelligent management system architecture tailored for hybrid VLC/RF networks. This system employs advanced algorithms and techniques to optimize resource allocation, load balancing, localization, and handover management, ensuring efficient operation and seamless connectivity.We evaluate the performance of our proposed solutions through extensive simulations and testbed experiments, considering different network scenarios and metrics. The results demonstrate significant improvements in terms of data rate, latency, handover success rate, and localization accuracy, validating the effectiveness of our proposed architecture and management system.Lastly, we explore several real-world applications and case studies of our intelligent management system in various indoor environments, such as retail stores, offices, and hospitals. These examples illustrate the practical benefits of our solution in enhancing customer experiences, optimizing operational efficiency, facilitating targeted marketing, and improving energy management.In conclusion, this thesis contributes to the advancement of hybrid VLC/RF networks by proposing an innovative architecture and intelligent management system that address the key challenges faced by these systems in indoor environments. The findings and solutions presented in this work provided the backbone for the future research and development efforts aimed at fully harnessing the potential of VLC technology in combination with RF networks

    Advanced Wireless LAN

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    The past two decades have witnessed starling advances in wireless LAN technologies that were stimulated by its increasing popularity in the home due to ease of installation, and in commercial complexes offering wireless access to their customers. This book presents some of the latest development status of wireless LAN, covering the topics on physical layer, MAC layer, QoS and systems. It provides an opportunity for both practitioners and researchers to explore the problems that arise in the rapidly developed technologies in wireless LAN
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