351,614 research outputs found
HTTP adaptive streaming with media fragment URIs
HTTP adaptive streaming was introduced with the general idea that user agents interpret a manifest file (describing different representations and segments of the media); where-after they retrieve the media content using sequential HTTP progressive download operations. MPEG started with the standardization of an HTTP streaming protocol, defining the structure and semantics of a manifest file and additional restrictions and extensions for container formats. At the same time, W3C is working on a specification for addressing media fragments on the Web using Uniform Resource Identifiers. The latter not only defines the URI syntax for media fragment identifiers but also the protocol for retrieving media fragments over HTTP. In this paper, we elaborate on the role of Media Fragment URIs within HTTP adaptive streaming scenarios. First, we elaborate on how different media representations can be addressed by means of Media Fragment URIs, by using track fragments. Additionally, we illustrate how HTTP adaptive streaming is realized relying on the Media Fragments URI retrieval protocol. To validate the presented ideas, we implemented Apple's HTTP Live streaming technique using Media Fragment URI
Architecture for Cooperative Prefetching in P2P Video-on- Demand System
Most P2P VoD schemes focused on service architectures and overlays
optimization without considering segments rarity and the performance of
prefetching strategies. As a result, they cannot better support VCRoriented
service in heterogeneous environment having clients using free VCR controls.
Despite the remarkable popularity in VoD systems, there exist no prior work
that studies the performance gap between different prefetching strategies. In
this paper, we analyze and understand the performance of different prefetching
strategies. Our analytical characterization brings us not only a better
understanding of several fundamental tradeoffs in prefetching strategies, but
also important insights on the design of P2P VoD system. On the basis of this
analysis, we finally proposed a cooperative prefetching strategy called
"cooching". In this strategy, the requested segments in VCR interactivities are
prefetched into session beforehand using the information collected through
gossips. We evaluate our strategy through extensive simulations. The results
indicate that the proposed strategy outperforms the existing prefetching
mechanisms.Comment: 13 Pages, IJCN
Content Creation Online
Presents findings from surveys conducted between March and May 2003. Measures the extent to which American adults have used the Internet to publish their thoughts, respond to others, post pictures, and share files
Inequalities in maternity care and newborn outcomes: one-year surveillance of births in vulnerable slum communities in Mumbai
Background: Aggregate urban health statistics mask inequalities. We described maternity care in
vulnerable slum communities in Mumbai, and examined differences in care and outcomes between
more and less deprived groups.
Methods: We collected information through a birth surveillance system covering a population of
over 280 000 in 48 vulnerable slum localities. Resident women identified births in their own
localities and mothers and families were interviewed at 6 weeks after delivery. We analysed data
on 5687 births over one year to September 2006. Socioeconomic status was classified using
quartiles of standardized asset scores.
Results: Women in higher socioeconomic quartile groups were less likely to have married and
conceived in their teens (Odds ratio 0.74, 95% confidence interval 0.69–0.79, and 0.82, 0.78–0.87,
respectively). There was a socioeconomic gradient away from public sector maternity care with
increasing socioeconomic status (0.75, 0.70–0.79 for antenatal care and 0.66, 0.61–0.71 for
institutional delivery). Women in the least poor group were five times less likely to deliver at home
(0.17, 0.10–0.27) as women in the poorest group and about four times less likely to deliver in the
public sector (0.27, 0.21–0.35). Rising socioeconomic status was associated with a lower
prevalence of low birth weight (0.91, 0.85–0.97). Stillbirth rates did not vary, but neonatal mortality
rates fell non-significantly as socioeconomic status increased (0.88, 0.71–1.08).
Conclusion: Analyses of this type have usually been applied across the population spectrum from
richest to poorest, and we were struck by the regularly stepped picture of inequalities within the
urban poor, a group that might inadvertently be considered relatively homogeneous. The poorest
slum residents are more dependent upon public sector health care, but the regular progression
towards the private sector raises questions about its quality and regulation. It also underlines the
need for healthcare provision strategies to take account of both sectors
A network resource availability model for IEEE802.11a/b-based WLAN carrying different service types
The electronic version of this article is the complete one and can be found online at: http://jwcn.eurasipjournals.com/content/2011/1/103.
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.Operators of integrated wireless systems need to have knowledge of the resource availability in their different access networks to perform efficient admission control and maintain good quality of experience to users. Network availability depends on the access technology and the service types. Resource availability in a WLAN is complex to gather when UDP and TCP services co-exist. Previous study on IEEE802.11a/b derived the achievable throughput under the assumption of inelastic and uniformly distributed traffic. Further study investigated TCP connections and derived a model to calculate the effective transmission rate of packets under the assumption of saturated traffic flows. The assumptions are too stringent; therefore, we developed a model for evaluating WLAN resource availability that tries to narrow the gap to more realistic scenarios. It provides an indication of WLAN resource availability for admitting UDP/TCP requests. This article presents the assumptions, the mathematical formulations, and the effectiveness of our model
Random Linear Network Coding for 5G Mobile Video Delivery
An exponential increase in mobile video delivery will continue with the
demand for higher resolution, multi-view and large-scale multicast video
services. Novel fifth generation (5G) 3GPP New Radio (NR) standard will bring a
number of new opportunities for optimizing video delivery across both 5G core
and radio access networks. One of the promising approaches for video quality
adaptation, throughput enhancement and erasure protection is the use of
packet-level random linear network coding (RLNC). In this review paper, we
discuss the integration of RLNC into the 5G NR standard, building upon the
ideas and opportunities identified in 4G LTE. We explicitly identify and
discuss in detail novel 5G NR features that provide support for RLNC-based
video delivery in 5G, thus pointing out to the promising avenues for future
research.Comment: Invited paper for Special Issue "Network and Rateless Coding for
Video Streaming" - MDPI Informatio
Weak ties: Subtle role of information diffusion in online social networks
As a social media, online social networks play a vital role in the social
information diffusion. However, due to its unique complexity, the mechanism of
the diffusion in online social networks is different from the ones in other
types of networks and remains unclear to us. Meanwhile, few works have been
done to reveal the coupled dynamics of both the structure and the diffusion of
online social networks. To this end, in this paper, we propose a model to
investigate how the structure is coupled with the diffusion in online social
networks from the view of weak ties. Through numerical experiments on
large-scale online social networks, we find that in contrast to some previous
research results, selecting weak ties preferentially to republish cannot make
the information diffuse quickly, while random selection can achieve this goal.
However, when we remove the weak ties gradually, the coverage of the
information will drop sharply even in the case of random selection. We also
give a reasonable explanation for this by extra analysis and experiments.
Finally, we conclude that weak ties play a subtle role in the information
diffusion in online social networks. On one hand, they act as bridges to
connect isolated local communities together and break through the local
trapping of the information. On the other hand, selecting them as preferential
paths to republish cannot help the information spread further in the network.
As a result, weak ties might be of use in the control of the virus spread and
the private information diffusion in real-world applications.Comment: Final version published in PR
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