199 research outputs found
P2P IPTV Measurement: A Comparison Study
With the success of P2P file sharing, new emerging P2P applications arise on
the Internet for streaming content like voice (VoIP) or live video (IPTV).
Nowadays, there are lots of works measuring P2P file sharing or P2P telephony
systems, but there is still no comprehensive study about P2P IPTV, whereas it
should be massively used in the future. During the last FIFA world cup, we
measured network traffic generated by P2P IPTV applications like PPlive,
PPstream, TVants and Sopcast. In this paper we analyze some of our results
during the same games for the applications. We focus on traffic statistics and
churn of peers within these P2P networks. Our objectives are threefold: we
point out the traffic generated to understand the impact they will have on the
network, we try to infer the mechanisms of such applications and highlight
differences, and we give some insights about the users' behavior.Comment: 10 page
Characterization of P2P IPTV Traffic: Scaling Analysis
P2P IPTV applications arise on the Internet and will be massively used in the
future. It is expected that P2P IPTV will contribute to increase the overall
Internet traffic. In this context, it is important to measure the impact of P2P
IPTV on the networks and to characterize this traffic. Dur- ing the 2006 FIFA
World Cup, we performed an extensive measurement campaign. We measured network
traffic generated by broadcasting soc- cer games by the most popular P2P IPTV
applications, namely PPLive, PPStream, SOPCast and TVAnts. From the collected
data, we charac- terized the P2P IPTV traffic structure at different time
scales by using wavelet based transform method. To the best of our knowledge,
this is the first work, which presents a complete multiscale analysis of the
P2P IPTV traffic. Our results show that the scaling properties of the TCP
traffic present periodic behavior whereas the UDP traffic is stationary and
lead to long- range depedency characteristics. For all the applications, the
download traffic has different characteristics than the upload traffic. The
signaling traffic has a significant impact on the download traffic but it has
negligible impact on the upload. Both sides of the traffic and its granularity
has to be taken into account to design accurate P2P IPTV traffic models.Comment: 27p, submitted to a conferenc
Estromatólitos siliciclásticos da Formação Caboclo, Mesoproterozóico da Chapada Diamantina, BA
Estromatólitos siliciclásticos são raros, espec ialmente no Proterozoico, e têm grande significado paleoambiental. A Formação Caboclo, formada no Mesoproterozoico, contém exemplos de depósitos estromatolíticos muito bem preservados, cuja composição contêm abundantes grãos siliciclásticos. A Formação Caboclo localiza-se no Cráton São Francisco, e faz parte do Supergrupo Espinhaço. Nos perfis Rio Preto e Rio Ventura, aflora a porção de topo da formação, composta por estromatólitos siliciclásticos intercalados com arenitos e pelitos depositados em ambiente marinho raso. Este trabalho, através da integração de dados de levantamento estratigráfico de detalhe, análise de lâminas delgadas, busca definir os diferentes tipos de estromatólitos e interpretar os processos que os originaram e, em conjunto com a análise das demais litofácies constituintes, reconstruir o modelo deposicional. Além disso, é feita uma revisão bibliográfica robusta sobre estromatólitos aglutinantes e estromatólitos siliciclásticos, que evidencia os fatores ambientais que controlam a deposição destes na história da Terra. Esse trabalho encontrou 15 fácies sedimentares, quatro delas de origem microbial, que ocorrem em três associações de fácies distintas, offshore, offshore transition e shoreface. Essas associações de fácies representam uma plataforma marinha dominada por ondas e tempestades. As quatro fácies microbiais têm evidências de biogenicicidade e são classificados como estromatólitos siliciclásticos. Comparando a Fm. Caboclo com os exemplos da bibliografia, é possível observar que grandes mudanças climáticas no Mesoproterozoico podem ter condicionado o surgimento dos estromatólitos aglutinantes na Terra.Siliciclastic stromatolites are rare, especially in the Proterozoic, and have great paleoenvironmental significance. Caboclo Formation, formed in the Mesoproterozoic, contains well - preserved specimens of stromatolites which have plenty siliciclastic grains in their fabrics. Caboclo Formation is located in São Francisco Craton , and is part of Espinhaço Supergroup. In the sedimentary sections studied, Ven tura River and Preto River, the upper part of Caboclo Formation is exposed, composed by siliciclastic stromatolites interspersed in sandstones and mudstones, deposited in a shallow marine environment. This work, through the integration of detailed stratigraphic data and thin sections, intends to define the different types of stromatolites and interpret the process that formed them, and with the analysis of all the litofacies, reconstruct the paleoenvironment of deposition. In addition, a robust literary review is made, on the theme of agglutinated and siliciclastic stromatolites, that highlights the environmental factors that control their deposition in Earth’s history. This work found 15 sedimentary facies, four of them of m icrobial origin, that occur in thr ee distinct facies associations, offshore, offshore transition and shoreface. These facies associations represent a wave and storm - dominated marine platform. The four microbial facies have clear evidences of biogenicity and are classified as siliciclastic stromatolites. Comparing Caboclo Fm. to the examples found in the literature , it’s possible to observe that big climatic changes in the Mesoproterozoic could have influenced the emergence of agglutinated stromatolites in Earth
Using Social Network Information into ICN
It was presented at NOMEN 2013 as a poster. NOMEN 2013 was a workshop held in IEEE INFOCOM 2013Online Social Networks carry extremely valuable information about their users and their relationships. We argue that this knowledge can help to drastically improve the efficiency of Information Centric Networks. In this paper, we propose a first step to include social infor- mation into ICN architectures. We conjecture a small number of users dominate the activity and receive most attention of others users in the social networks and we argue they produce content that will be more likely to be consumed, and in consequence their content must be replicated. We then propose a caching strategy based on prioritizing their content. We simulate a social network model where the proposed caching strategy is evaluated against common ICN caching strategies. Finally, we show that inclusion of social information into ICN networks may help to improve cache performances
SRSC: SDN-based Routing Scheme for CCN
International audienceContent delivery such as P2P or video streaming generates the main part of the Internet traffic and Content Centric Network (CCN) appears as an appropriate architecture to satisfy the user needs. However, the lack of scalable routing scheme is one of the main obstacles that slows down a large deployment of CCN at an Internet-scale. In this paper we propose to use the Software-Defined Networking (SDN) paradigm to decouple data plane and control plane and present SRSC, a new routing scheme for CCN. Our solution is a clean-slate approach using only CCN messages and the SDN paradigm. We implemented our solution into the NS-3 simulator and perform simulations of our proposal. SRSC shows better performances than the flooding scheme used by default in CCN: it reduces the number of messages, while still improves CCN caching performances
A Comparison of Caching Strategies for Content Centric Networking
International audienceContent Centric Networking (CCN) is a new architecture for a future Internet. CCN relies on in-network caching capabilities of nodes and the efficiency of this architecture depends drastically on performances of caching strategies. Thus, there have been a lot of studies proposing new caching strategies to improve the performances of CCN. However, among all these strategies, it is still unclear which one performs better as there is a lack of common environment to compare these strategies. In this paper, we compare the performances of CCN caching strategies within the same simulation environment. We build a common evaluation scenario and we compare via simulation five relevant caching strategies: Leave Copy Everywhere (LCE), Leave Copy Down (LCD), ProbCache, Cache " Less " For More and MAGIC. We analyze the performances of all the strategies in terms of Cache Hit, Stretch, Diversity and Complexity, and determine the cache strategy that fits the best with every scenario
MPC: Popularity-based Caching Strategy for Content Centric Networks
International audienceContent Centric Networking (CCN) has recently emerged as a promising architecture to deliver content at large- scale. It is based on named-data where a packet address names content and not its location. Then, the premise is to cache content on the network nodes along the delivery path. An important feature for CCN is therefore to manage the cache of the nodes. In this paper, we present Most-Popular Content (MPC), a new caching strategy adapted to CCN networks. By caching only popular content, we show through extensive simulation experiments that MPC is able to cache less content while, at the same time, it still achieves a higher Cache Hit and outperforms existing default caching strategy in CCN
Pulse oximetry in primary care: factors affecting accuracy and interpretation
The COVID-19 pandemic saw a rapid increase in the use of pulse oximetry devices (PODs) in primary care to triage and monitor large numbers of patients and to help decide which patients required admission to hospital. In the UK, this included providing 300 000 PODs to patients as part of the ‘virtual ward’ programme and there have been calls to extend the use of remote monitoring to patients with other medical conditions.1–3 However, the increased use of pulse oximetry has been accompanied by growing concern over the potential for PODs to produce inaccurate oxygen saturation (SpO2) readings and the effect that this could have on critical decisions regarding the management of patients. This article discusses the factors that can lead to inaccurate SpO2 readings and the implications that this could have for both GPs and patients
Croissance Verte dans NDN: Déploiement des Content Stores
International audienceL'architecture Named-Data Networking (NDN) consiste en un réseau de caches, o` u les noeuds peuvent stocker les données qui transitent pour satisfaire les futures requêtes. La mémoire requisè a chaque noeud, appelée Content Store, représente ainsi la majeure partie du coût de l'infrastructure. Cet article se propose d'´ etudier s'il est utile que tous les noeuds soient equipés de Content Stores pour améliorer les performances de l'architecture NDN. Pour cela, nous etudions l'impact du nombre de Content Stores dans un réseau NDN et evaluons ses performances. Nous montrons a travers d'importantes expériences de simulations avec NS-3 et son module ndnSIM que les performances de NDN sont optimales avec seulement 50% de noeuds equipés de Content Stores. C'est un résultat important pour les opérateurs réseaux car cela montre que l'architecture NDN peut etre déployéè a un coût d'infrastructure réduit
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