734 research outputs found

    CloudJet4BigData: Streamlining Big Data via an Accelerated Socket Interface

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    Big data needs to feed users with fresh processing results and cloud platforms can be used to speed up big data applications. This paper describes a new data communication protocol (CloudJet) for long distance and large volume big data accessing operations to alleviate the large latencies encountered in sharing big data resources in the clouds. It encapsulates a dynamic multi-stream/multi-path engine at the socket level, which conforms to Portable Operating System Interface (POSIX) and thereby can accelerate any POSIX-compatible applications across IP based networks. It was demonstrated that CloudJet accelerates typical big data applications such as very large database (VLDB), data mining, media streaming and office applications by up to tenfold in real-world tests

    End-to-End Simulation of 5G mmWave Networks

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    Due to its potential for multi-gigabit and low latency wireless links, millimeter wave (mmWave) technology is expected to play a central role in 5th generation cellular systems. While there has been considerable progress in understanding the mmWave physical layer, innovations will be required at all layers of the protocol stack, in both the access and the core network. Discrete-event network simulation is essential for end-to-end, cross-layer research and development. This paper provides a tutorial on a recently developed full-stack mmWave module integrated into the widely used open-source ns--3 simulator. The module includes a number of detailed statistical channel models as well as the ability to incorporate real measurements or ray-tracing data. The Physical (PHY) and Medium Access Control (MAC) layers are modular and highly customizable, making it easy to integrate algorithms or compare Orthogonal Frequency Division Multiplexing (OFDM) numerologies, for example. The module is interfaced with the core network of the ns--3 Long Term Evolution (LTE) module for full-stack simulations of end-to-end connectivity, and advanced architectural features, such as dual-connectivity, are also available. To facilitate the understanding of the module, and verify its correct functioning, we provide several examples that show the performance of the custom mmWave stack as well as custom congestion control algorithms designed specifically for efficient utilization of the mmWave channel.Comment: 25 pages, 16 figures, submitted to IEEE Communications Surveys and Tutorials (revised Jan. 2018

    Cabernet: A Content Delivery Network for Moving Vehicles

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    This paper describes the design, implementation, and evaluation of Cabernet, a system to deliver data to and from moving vehicles using open 802.11 (WiFi) access points encountered opportunistically during travel. Network connectivity in Cabernet is both fleeting (access points are typicallywithin range for a few seconds) and intermittent (because the access points don't provide continuous coverage), and suffers from high packet loss rates over the wireless channel. On the positive side, in the absence of losses, achievable data rates over WiFi can reach many megabits per second. Unfortunately, current protocols don't establish end-to-end connectivity fast enough, don't cope well with intermittent connectivity, and don't handle high packet loss rates well enough to achieve this potential throughput. Cabernet incorporates two new techniques to improve data delivery throughput: QuickWifi, a streamlined client-side process to establish end-to-end connectivity quickly, reducing the mean time to establish connectivity from 12.9 seconds to less than 366 ms and CTP, a transport protocol that distinguishes congestion on the wired portion of the path from losses over the wireless link to reliably and efficiently deliver data to nodes in cars. We have deployed the system on a fleet of 10 taxis, each running several hours per day in the Boston area. Our experiments show that CTP improves throughput by a factor of 2x over TCP and that QuickWifi increases the number of connectionsby a factor of 4x over unoptimized approaches. Thus, Cabernet is perhaps the first practical system capable of delivering data to moving vehicles over existing short-range WiFi radios, with a mean transfer capacity of approximately 38 megabytes/hour per car, or a mean rate of 87 kbit/s

    Through a router darkly: how new American copyright enforcement initiatives may hinder economic development, net neutrality and creativity

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    On November 1, 2012, Russia enacted a law putatively aiming to protect Russian children from pedophiles. This law authorizes deep packet inspection (DPI), a method used for monitoring, filtering and shaping internet traffic, which has heightened concerns among many leading privacy groups. These groups are concerned with how the government will use such an intrusive method in prosecuting child predators. Central to this concern is DPI’s capability to allow the Russian government to peer into any citizens’ unencrypted internet traffic and monitor, copy, or even alter the traffic as it moves to its destination. The unresolved question is whether the government’s use of DPI will be restrained and utilized primarily to thwart child predators, or whether it will be expanded to lay the groundwork for a new era of national censorship. Although the United States has not yet adopted similar tactics in regulating its citizens’ internet use, Russia’s implementation of the new DPI monitoring and filtering system will provide an educational opportunity for both privacy advocates and policymakers

    Delay Tolerant Networking over the Metropolitan Public Transportation

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    We discuss MDTN: a delay tolerant application platform built on top of the Public Transportation System (PTS) and able to provide service access while exploiting opportunistic connectivity. Our solution adopts a carrier-based approach where buses act as data collectors for user requests requiring Internet access. Simulations based on real maps and PTS routes with state-of-the-art routing protocols demonstrate that MDTN represents a viable solution for elastic nonreal-time service delivery. Nevertheless, performance indexes of the considered routing policies show that there is no golden rule for optimal performance and a tailored routing strategy is required for each specific case

    Satellite Networks: Architectures, Applications, and Technologies

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    Since global satellite networks are moving to the forefront in enhancing the national and global information infrastructures due to communication satellites' unique networking characteristics, a workshop was organized to assess the progress made to date and chart the future. This workshop provided the forum to assess the current state-of-the-art, identify key issues, and highlight the emerging trends in the next-generation architectures, data protocol development, communication interoperability, and applications. Presentations on overview, state-of-the-art in research, development, deployment and applications and future trends on satellite networks are assembled

    Taking the Politics Out of Satellite and Space-Based Communications Protocols

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    After many years of studies, experimentation, and deployment, large amounts of misinformation and misconceptions remain regarding applicability of various communications protocols for use in satellite and space-based networks. This paper attempts to remove much of the politics, misconceptions, and misinformation that have plagued spacebased communications protocol development and deployment. This paper provides a common vocabulary for communications; a general discussion of the requirements for various communication environments; an evaluation of tradeoffs between circuit and packet-switching technologies, and the pros and cons of various link, network, transport, application, and security protocols. Included is the applicability of protocol enhancing proxies to NASA, Department of Defense (DOD), and commercial space communication systems

    Applications of satellite technology to broadband ISDN networks

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    Two satellite architectures for delivering broadband integrated services digital network (B-ISDN) service are evaluated. The first is assumed integral to an existing terrestrial network, and provides complementary services such as interconnects to remote nodes as well as high-rate multicast and broadcast service. The interconnects are at a 155 Mbs rate and are shown as being met with a nonregenerative multibeam satellite having 10-1.5 degree spots. The second satellite architecture focuses on providing private B-ISDN networks as well as acting as a gateway to the public network. This is conceived as being provided by a regenerative multibeam satellite with on-board ATM (asynchronous transfer mode) processing payload. With up to 800 Mbs offered, higher satellite EIRP is required. This is accomplished with 12-0.4 degree hopping beams, covering a total of 110 dwell positions. It is estimated the space segment capital cost for architecture one would be about 190Mwhereasthesecondarchitecturewouldbeabout190M whereas the second architecture would be about 250M. The net user cost is given for a variety of scenarios, but the cost for 155 Mbs services is shown to be about $15-22/minute for 25 percent system utilization

    Experimental Verification of a Radio-Frequency Power Model for Wi-Fi Technology

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    When assessing the power emitted from a Wi-Fi network, it has been observed that these networks operate at a relatively low duty cycle. In this paper, we extend a recently introduced model of emitted power in Wi-Fi networks to cover conditions where devices do not always have packets to transmit. We present experimental results to validate the original model and its extension by developing approximate, but practical, testbed measurement techniques. The accuracy of the models is confirmed, with small relativ
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