Mobility Support in IP Multicast: Proposals Review and
Anwar and S.A.L.
Multicast is one-to-many or many-to-many delivery of packets. Multicast
data delivery increases network efficiency and decreases the bandwidth
demand by eliminating the need for redundant packets when more than one
client wishes to access a data stream. With this in mind, the importance
of multicast routing becomes evident. However, the main drawback of the
current multicast routing protocols is that they are developed without
mobility in mind. It is anticipated that many users are likely to become
mobile in the near future, thus mechanisms are needed to support
multicast for the groups whose members are both mobile and static. The
main aim of this paper is to study and evaluate the current approaches
for mobility support in multicast. It presents the main concepts of
multicast. It also performs a study and evaluation to the Internet
Engineering Force Task (IEFT) approaches to handle the mobility of the
multicast users. Then the discussion is extended to include different
protocols that are introduced to overcome the limitations of IEFT
proposals highlighting their advantages and limitations.
On Some Current Results of Graph Theory for ad-hoc Networks
Marco and L.
The goal of this paper is twofold. Firstly, we present
results from graph-theory which can be used to understand the
fundamental properties of ad-hoc networks and wireless sensor networks.
Graph-theory is a well studied branch of discrete mathematics, and it
has been applied in many knowledge fields, e.g. social network, Internet
tomography and epidemiology. We review literature results from the point
of view of the designer of an ad-hoc network, who must set simulation
parameters in order to predict the behaviour of the real network.
Secondly, we study the impact of the asymmetries of radio links on the
connectivity properties of an ad-hoc network. To the best knowledge of
the author, this further hypothesys has been addressed in the case of
geometric random graph only, but not for radio models with randomnesses.
As expected, we found that randomness in the radio model directly
affects the distribution of the asymmetries and the connectivity
properties. This result can be very useful in the understanding of more
complicated aspects of ad-hoc nets, like routing and coordinated wake-up
in power saving techniques.
On Asynchronous Training in Sensor Networks
Q.-W. Xu, R.
Olariu, and S.
Due to their small form factor and modest energy budget
it is infeasible to endow individual sensors with GPS capabilities. Yet,
numerous applications require sensors to have a coarse-grain
location awareness. The task of acquiring this coarse-grain location
awareness is referred to as training. The main contribution of
this work is to propose a fully asynchronous training protocol for
massively-deployed sensor networks. The sensors wake up according to
their internal clock and are not engaging in synchronization with the
sink. Our protocol is lightweight and simple to implement. We show
analytically that in spite of the lack of synchronization, individual
sensors are trained energy-efficiently. The analytical results have been
confirmed by simulation.
Evaluation of the Delivered MPEG Video Quality over Wireless Channels
C.-H. Ke, C.-H. Lin, G.-K. Shieh, W.-S. Huang, A.
We propose an analytical model
to derive from the packet loss rate an objective application-level
metric, the decodable frame rate (Q), thus allowing the evaluation of
the packet loss effect on the streaming MPEG video quality over wireless
channels, as perceived by end users. We analyze the effects on video
quality using a random uniform error model and the Gilbert-Elliot (GE)
error model (for burst errors modeling) to represent wireless lossy
channels. Results obtained through extensive simulations indicate the
effectiveness of our proposed model for both the random uniform and GE
error models, provided that the packet error rate remains relatively
low. Moreover, owing to the well-acceptance of PSNR as an objective
performance metric that takes into account the video content to assess
the video quality, we also investigate the relationship between PSNR and
Q as well as their comparative performances as metrics for video quality
assessment. Results show that the Q metric reflects well the behavior of
the PSNR metric, whereas being much less time-consuming.
Multimedia Applications for Mobile Devices: Issues and Requirements
for Authoring Tools and Development Platforms
D. Economou, D. Gavalas, M. Kenteris, and K. Micha
This paper explores requirements
application authoring tools should satisfy for the development of
cultural applications tailored for deployment on Personal Digital
Assistants (PDAs) and mobile phones. The paper reviews the use of mobile
technologies in the context of cultural organizations and tourism. It
identifies and evaluates the development and design facilities provided
by state-of-the-art multimedia application development tools for PDAs
and mobile phones: Macromedia Flash Lite, Navipocket and Java 2 Micro
Edition. It describes the way these tools have been used in the
implementation phase of two projects that have been developed at the
Cultural Heritage Management Lab (CHMLab), at the Department of Cultural
Technology and Communication, University of the Aegean. These projects
focus on the use of PDAs and mobile phones for providing cultural and
tourist information, keeping the visitors’ interest and attention, as
well as promoting various cultural organizations’ and tourist
facilities. Based on these two case studies the paper extracts a set of
PDA and mobile phone application requirements. The paper concludes with
a set of suggestions related to the way application authoring tools
should be exploited in order to gratify application and designer needs
for developing operational and profitable cultural and tourist
Potentials of SMIL Applications for Mobile Devices
Stormer and M.E. Ritz
The Synchronized Multimedia Integration Language (SMIL)
is an XML based language for the synchronization of multimedial content.
SMIL can be used to show all kinds of presentations on stationary and
mobile devices. For the latter, a subset called SMIL mobile profile is
standardized. SMIL has already started to influence certain mobile
applications. Worth mentioning are electronic learning and mobile
marketing, who both profit from utilizing SMIL presentations. This paper
gives an introduction to SMIL. The different modules that establish a
SMIL presentation are presented. Afterwards, mobile application
scenarios that benefit from the usage of SMIL are shown, including
e-learning, mobile communication and mobile marketing.
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