IMDEA Networks Institute Digital Repository
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1915 research outputs found
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Demonstration Abstract: Research Platform for Visible Light Communication and Sensing Systems
Get PDFOpenVLC (\url{www.openvlc.org}) is an open-source project for research in Visible Light Communication (VLC) systems. It has the potential to help create a new type of infrastructure, an Internet of Lights (IoL), where LED-based devices (e.g., car lights, city lights, billboards, toy, etc) and photodetectors become inter-connected. OpenVLC is built upon an embedded platform and adopts off-the-shelf optical devices and essential electronic components. It has been proved to be a starter kit for VLC research, thanks to its deployments by tens of top universities/research centers in the world (\url{www.openvlc.org/list-of-users.html}). This demo introduces its latest version: OpenVLC1.1. The new features include: (1) higher resilience to ambient light noise, e.g., indoor interfering lighting; (2) interface for sensor application. A new board (OpenVLC1.1 cape) is designed and the printed circuit is developed. The cape is plugged directly into the main embedded board and external sensors can be easily connected to the cape. This demo demonstrates OpenVLC1.1's networking performance through standard networking diagnostic tools and shows an application wherein temperature and humidity sensed data are transmitted through VLC links.TRUEpu
Pushing the Frontier: Exploring the African Web Ecosystem
Get PDFIt is well known that Africa’s mobile and fixed Internet infrastructure is progressing at a rapid pace. A flurry of re- cent research has quantified this, highlighting the expansion of its underlying connectivity network. However, improving the infrastructure is not useful without appropriately provisioned services to utilise it. This paper measures the avail- ability of web content infrastructure in Africa. Whereas others have explored web infrastructure in developed regions, we shed light on practices in developing regions. To achieve this, we apply a comprehensive measurement methodology to collect data from a variety of sources. We focus on a large content delivery network to reveal that Africa’s content infrastructure is, indeed, expanding. However, we find much web content is still served from the US and Europe. We dis- cover that many of the problems faced are actually caused by significant inter-AS delays in Africa, which contribute to local ISPs not sharing their cache capacity. We discover that a related problem is the poor DNS configuration used by some ISPs, which confounds the attempts of providers to optimize their delivery. We then explore a number of other websites to show that large web infrastructure deployments are a rarity in Africa and that even regional websites host their services abroad. We conclude by making suggestions for improvements.TRUEpu
Implementation of a Multi-modal Acoustic-Optic Underwater Network Protocol Stack
Get PDFWe describe the implementation of a protocol stack for multi-modal underwater networks, where multiple physical layer technologies are available to each node. This condition implies greater flexibility, by allowing each node to decide how to serve specific transmissions and traffic classes depending on system, quality-of-service, and application-specific policies implemented in a controller. In this paper, we describe the implementation details of an acoustic/optic multi-modal underwater network stack through the DESERT Underwater framework. Our system services various traffic types of different quality-of-service demands, and allows mobility. Extensive numerical results show that our multi-modal system offers greater throughput, robustness to mobility and traffic types, and provides much lower service delay.TRUEpu
Challenges and Solutions for Millimeter-Wave Wireless Networks
No full textOne of the most promising options to significantly increase data rates in future wireless networks is to vastly increase the communication bandwidth. Such very high bandwidth channels are only available in the extremely high frequency part of the radio spectrum, the millimeter wave band (mm-wave). Upcoming communication technologies, for example IEEE 802.11ad, are already starting to exploit this part of the radio spectrum to achieve data rates of several GBit/s. mm-wave communication is also discussed as key technology for 5G mobile networks. However, communication at such high frequencies also suffers from high attenuation and signal absorption, often restricting communication to line-of-sight scenarios and requiring the use of highly directional antennas. This in turn requires a radical rethinking of wireless network design. On the one hand side, such channels experience little interference, allowing for a high degree of spatial reuse and potentially simpler MAC and interference management mechanisms. On the other hand, such an environment is extremely dynamic and channels may appear and disappear over very short time intervals, in particular for mobile devices. It is essential to take these characteristics into account to design efficient wireless architectures. The talk will highlight main challenges and possible solutions for networking in the mm-wave band.FALSEpu
A Multi-perspective Analysis of Carrier-Grade NAT Deployment
Get PDFAs ISPs face IPv4 address scarcity they increasingly turn to network address translation (NAT) to accommodate the address needs of their customers. Recently, ISPs have moved beyond employing NATs only directly at individual customers and instead begun deploying Carrier-Grade NATs (CGNs) to apply address translation to many independent and disparate endpoints spanning physical locations, a phenomenon that so far has received little in the way of empirical assessment. In this work we present a broad and systematic study of the deployment and behavior of these middleboxes. We develop a methodology to detect the existence of hosts behind CGNs by extracting non-routable IP addresses from peer lists we obtain by crawling the BitTorrent DHT. We complement this approach with improvements to our Netalyzr troubleshooting service, enabling us to determine a range of indicators of CGN presence as well as detailed insights into key properties of CGNs. Combining the two data sources we illustrate the scope of CGN deployment on today's Internet, and report on characteristics of commonly deployed CGNs and their effect on end users.TRUEpu
Exploring the Use of RPAs as 5G Points of Presence
Get PDFThis paper presents an early exploration and preliminary results on the use of Remotely Piloted Aircrafts (RPA) as 5G points of presence. The use of RPAs in the 5G arena would enable a cost-effective deployment of functions over mobile nodes that could be integrated on demand into the programmable and unified 5G infrastructure, enhancing the capacity of the network to flexibly adapt to the particular service requirements in a geographical area. As a first step, we evaluate the feasibility and the cost, in terms of energy consumption, of using virtualisation techniques over resource-constrained aerial vehicle platforms, as a fundamental software technology in the evolution towards 5G. We complement this evaluation presenting a proof-of-concept that considers the use of these platforms to enable real-time 5G communications in emergency cases.TRUEpu
Experimental Evaluation of an SDN-based Distributed Mobility Management Solution
Get PDFThe current wireless network architecture needs to be re-thought to support mobility in very dense and heterogeneous network deployments. We propose and experimentally evaluate a novel SDN-based architecture which makes use of DMM concepts to deploy fast, flexible, reliable, and scalable mobility management mechanisms at both local and regional scopes. Our solution is compatible with existing protocols deployed in wireless access and backhaul networks, and is therefore technology transparent to the user. Although our architecture is generic and can be used with heterogeneous wireless networks, we prove the validity of our approach in a lab prototype, by implementing our distributed mobility management mechanism
on a set of OpenFlow-controlled IEEE 802.11 networks.TRUEpu
Inter-domain traffic management in an evolving Internet peering ecosystem
Get PDFThe operators of the Autonomous Systems (ASes) composing the Internet must deal with a constant traffic growth, while striving to reduce the overall cost-per-bit and keep an acceptable quality of service. These challenges have motivated ASes to evolve their infrastructure from basic
interconnectivity strategies, using a couple transit providers and a few settlement-free peerings, to employ geographically scoped transit services (e.g. partial transit) and multiplying their peering efforts. Internet Exchange Points (IXPs), facilities allowing the establishment of sessions to multiple networks using the same infrastructure. IXPs have hence become central entities
of the Internet. Although the benefits of a diverse interconnection strategy are manifold, it also encumbers the inter-domain traffic engineering process, and potentially increases the effects of incompatible interests with neighboring ASes. To efficiently manage the inter-domain traffic under such challenges, operators should rely on monitoring systems and computer supported decisions.
This thesis explores the IXP-centric inter-domain environment, the managing obstacles arising from it, and proposes mechanisms for operators to tackle them. The thesis is divided in two parts. The first part examines and measures the global characteristics of the inter-domain ecosystem. We characterize several IXPs around the world, comparing them in terms of their number of members and the properties of the traffic they exchange. After highlighting the problems arising from the member overlapping among IXPs, we introduce remote peering, an interconnection
service that facilitates the connection to multiple IXPs. We describe this service and measure its adoption in the Internet. In the second part of the thesis, we take the position of the network operators. We detail the challenges surrounding the control of inter-domain traffic in the Internet environment previously described, and introduce an operational framework aimed at facilitating its management. Subsequently, we examine methods that peering coordinators and network engineers can use to plan their infrastructure investments, by quantifying the benefits of new interconnections. Finally, we delve into the effects of conflicting business objectives among ASes. These conflicts can result in traffic distributions which do not satisfy the (business) interests of one or more ASes. We describe these dissatisfactions, differentiating their impact on the ingress and egress traffic of a single AS. Furthermore, we develop a warning system that operators can use to detect and rank those conflicts. We test our warning system using data from two real networks, where we discover a large number of traffic flows that do not satisfy the interest of operators, thus stressing the need to identify the ones having a larger impact on their network.Telematics EngineeringUniversidad Carlos III de Madrid, Spainpu
Understanding the Detection of View Fraud in Video Content Portals
Get PDFISBN: 978-1-4503-4143-1
DOI: http://dx.doi.org/10.1145/2872427.2882980While substantial effort has been devoted to understand fraudulent activity in traditional online advertising (search and banner), more recent forms such as video ads have received little attention. The understanding and identification of fraudulent activity (i.e., fake views) in video ads for advertisers, is complicated as they rely exclusively on the detection mechanisms deployed by video hosting portals. In this context, the development of independent tools able to monitor and audit the fidelity of these systems are missing today and needed by both industry and regulators.
In this paper we present a first set of tools to serve this purpose. Using our tools, we evaluate the performance of the audit systems of five major online video portals. Our results reveal that YouTube's detection system significantly outperforms all the others. Despite this, a systematic evaluation indicates that it may still be susceptible to simple attacks. Furthermore, we find that YouTube penalizes its videos' public and monetized view counters differently, the former being more aggressive. This means that views identified as fake and discounted from the public view counter are still monetized. We speculate that even though YouTube's policy puts in lots of effort to compensate users after an attack is discovered, this practice places the burden of the risk on the advertisers, who pay to get their ads displayed.TRUEpu