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Distributed Management of Application Layer Multicast Trees for IPTV Services
Get PDFIP multicast is an eff cient mechanism to distribute IPTV content towards multiple users, but nowadays Internet Providers f lter out this kind of traff c, mainly due to security and accounting issues. In order to overcome this f ltering, the same idea of IP multicast can be implemented at the end user terminals, but implementing multicast trees at the application layer, also known as Application Layer Multicast (ALM). ALM has some drawbacks, mainly due to dynamic behavior of users, joining and leaving the trees. In order to minimize the impact of this behavior, this paper proposes a distributed management for ALM in IPTV, instead of a centralized one, where some nodes connected to a tree will be on charge of the management of that tree. Furthermore, all nodes are dynamically conf gured with the substitute of its parent node in order to accelerate the reconnection process. Results presented in this article show that this proposal provides fast reconstructions and low management load per node, while keeping a balanced tree topology.TRUEpu
A Cost Sensitivity Analysis for Carrier Grade Wireless Mesh Networks with Tabu Optimization
Get PDFWe present an insight on the sensitivity of total cost
(CAPEX+OPEX) towards various key input parameters for
CARrier Grade Wireless MEsh Networks (CARMEN).
deployment These input parameters span across three main
categories namely the network design options, environment
conditions and cost. Various boundary conditions are imposed to
allow network operator to understand the impacts of parametersK
changes with the highest level of uncertainty. A simple Tabu
optimization method is adopted to optimize the node density
against target data rate and range.TRUEpu
Detecting Selfish Configurations in 802.11 WLANs
Get PDFLately, there has been an increase in the number of IEEE 802.11 devices that provide users with the ability to modify the MAC parameters or do not conform to the standard specification. This increases the risk of having a WLAN with
selfish stations that, through the CSMA/CA parameters, obtain
a larger share of the resources at the expense of well-behaved
users. In this letter we propose a mechanism to detect these
selfish stations that, unlike previous approaches, is not based on heuristics nor makes any assumption about radio conditions.TRUEpu
A First Step Towards User Assisted Online Social Networks
Get PDFThe current Online Social Networks' infrastructure is com-
posed by thousands of servers distributed across data-centers
spread over several geographical locations. These servers
store all the users' information (profile, contacts, contents,
etc). Such an infrastructure incurs high operational and
maintenance costs. Furthermore, this may threaten the scal-
ability, the reliability, the availability and the privacy of the
offered service. On the other hand this centralized approach
gives to the OSN provider full control over a huge amount of
valuable information. This information constitutes the basis
of the OSN provider's business.
Most of the storage capacity is dedicated to store the
user's content (e.g. photos, videos, etc). We believe that
OSN provider does not have strong incentive to dedicate a
large part of its infrastructure to store majority part of this
content.
In this position paper we introduce the concept of user
assisted Online Social Network (uaOSN). This novel archi-
tecture seeks to distribute the storage load associated to the
content (e.g. photos, videos, etc) among the OSN's users.
Thus the OSN provider keeps the control on the relevant in-
formation while reducing the operational and maintenance
costs. We discuss the benefits that this proposal may pro-
duce for both, the OSN provider and the users. We also
discuss the technical aspects to be considered and compare
this solution to other distributed approaches.TRUEpu
Special Issue on "Wireless Multi-Hop Networking for Infrastructure Access" [Editorial]
No full textTRUEpu
Multimodal Vision-Haptic Perception of Digital Watermarks Embedded in 3D Meshes
Get PDFIn this paper, a study is conducted to investigate the
role of multisensory feedback in the perception of a watermark embedded in a haptic-enabled 3-D virtual surface. Specifically, we focus on whether the use of a bimodal approach, where a subject is looking at, and touching a 3-D mesh could in fact improve the perceptibility of a watermark as opposed to when only a single modality (vision-alone or haptic-alone) is available. The experiments are performed using a vision–haptic interface that enables users to see and touch virtual objects at the same location in space. This approach enables superior integration of vision and touch than a conventional 2-D screen-based display. An analysis of variance (ANOVA) is also conducted to statistically explore the impact of the considered modalities (vision, haptic, and vision–haptic) on the measured watermark detection thresholds across
different resolutions of the underlying virtual 3-D mesh. Overall, the results suggest that relying on bimodal vision–haptic feedback is better than any of the single modalities when detecting a watermark embedded in a 3-D model. In addition, it has been assessed that the impact of the selected modality on the perceptibility of the 3-D watermark is independent of the chosen surface resolution.TRUEpu
FloorNet: Deployment and Evaluation of a Multihop Wireless 802.11 Testbed
Get PDFEISSN: 1687-1499A lot of attention has been given to multihop wireless
networks lately, but further research –in particular, through experimentation– is needed. This attention has motivated an increase in the number of 802.11-based deployments, both indoor and outdoor. These testbeds, which require a significant amount of resources during both deployment and maintenance, are used to run measurements in order to analyze and understand the limitation and differences between analytical or simulation-based figures and the results from real-life experimentation. This paper
makes two major contributions: i) first, we describe a novel wireless multihop testbed, which we name FloorNet, that is deployed and operated under the false floor of a lab in our Computer Science building. This false floor provides a strong physical protection that prevents disconnections or misplacements, as well as radio shielding (to some extent) thanks to the false floor panels –this later feature is assessed through experimentation; ii) second, by running exhaustive and controlled experiments we are able to analyze the performance limits of commercial off-the-shelf hardware, as well as to derive practical design criteria for the deployment and configuration of mesh networks.
These results both provide valuable insights of wireless multihop performance and prove that FloorNet constitutes a valuable asset to research on wireless mesh networks.TRUEpu
Providing Service Guarantees in Heterogeneous Wireless Mesh Networks
No full textPresented at IEEE 802.21 session #37 in Orlando, FLThis presentation shows how to abstract the capacity concept of the specific wireless technologies.pu
Detecting algorithmically generated malicious domain names
Get PDFRecent Botnets such as Conficker, Kraken and Torpig have
used DNS based “domain fluxing” for command-and-control,
where each Bot queries for existence of a series of domain
names and the owner has to register only one such domain
name. In this paper, we develop a methodology to detect
such “domain fluxes” in DNS traffic by looking for patterns
inherent to domain names that are generated algorithmically, in contrast to those generated by humans. In particular, we look at distribution of alphanumeric characters as
well as bigrams in all domains that are mapped to the same
set of IP-addresses. We present and compare the performance of several distance metrics, including KL-distance,
Edit distance and Jaccard measure. We train by using a
good data set of domains obtained via a crawl of domains
mapped to all IPv4 address space and modeling bad data
sets based on behaviors seen so far and expected. We also
apply our methodology to packet traces collected at a Tier-1
ISP and show we can automatically detect domain fluxing
as used by Conficker botnet with minimal false positivesTRUEpu
Wireless access architectures for video applications: the approach proposed in the MEDIEVAL project
Get PDFISSN: 1530-1346, ISBN: 978-1-4244-7754-8 (Print)Video transmission is expected to be the next big
thing in personal communication systems. While text messaging
applications have already experienced an explosive growth, the
exchange of multimedia content is still lacking architectural
solutions which enable it to become the next killer application.
The EU project MEDIEVAL (MultimEDia transport for mobIlE
Video AppLications) [1] aims at filling this gap. In this paper
we describe the approaches envisioned by the project for what
concerns the data link layer, with special emphasis on wireless
access and its related cross-layer issues. After presenting some
general project aspects, we will review the state of the art and
enumerate several open issues, concerning the identification of
the most suitable radio technologies for video support, as well as
their integration and required enhancements to enable efficient
video transport.TRUEpu