152 research outputs found
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Multimedia delivery in the future internet
The term âNetworked Mediaâ implies that all kinds of media including text, image, 3D graphics, audio
and video are produced, distributed, shared, managed and consumed on-line through various networks,
like the Internet, Fiber, WiFi, WiMAX, GPRS, 3G and so on, in a convergent manner [1]. This white
paper is the contribution of the Media Delivery Platform (MDP) cluster and aims to cover the Networked
challenges of the Networked Media in the transition to the Future of the Internet.
Internet has evolved and changed the way we work and live. End users of the Internet have been confronted
with a bewildering range of media, services and applications and of technological innovations concerning
media formats, wireless networks, terminal types and capabilities. And there is little evidence that the pace
of this innovation is slowing. Today, over one billion of users access the Internet on regular basis, more
than 100 million users have downloaded at least one (multi)media file and over 47 millions of them do so
regularly, searching in more than 160 Exabytes1 of content. In the near future these numbers are expected
to exponentially rise. It is expected that the Internet content will be increased by at least a factor of 6, rising
to more than 990 Exabytes before 2012, fuelled mainly by the users themselves. Moreover, it is envisaged
that in a near- to mid-term future, the Internet will provide the means to share and distribute (new)
multimedia content and services with superior quality and striking flexibility, in a trusted and personalized
way, improving citizensâ quality of life, working conditions, edutainment and safety.
In this evolving environment, new transport protocols, new multimedia encoding schemes, cross-layer inthe
network adaptation, machine-to-machine communication (including RFIDs), rich 3D content as well as
community networks and the use of peer-to-peer (P2P) overlays are expected to generate new models of
interaction and cooperation, and be able to support enhanced perceived quality-of-experience (PQoE) and
innovative applications âon the moveâ, like virtual collaboration environments, personalised services/
media, virtual sport groups, on-line gaming, edutainment. In this context, the interaction with content
combined with interactive/multimedia search capabilities across distributed repositories, opportunistic P2P
networks and the dynamic adaptation to the characteristics of diverse mobile terminals are expected to
contribute towards such a vision.
Based on work that has taken place in a number of EC co-funded projects, in Framework Program 6 (FP6)
and Framework Program 7 (FP7), a group of experts and technology visionaries have voluntarily
contributed in this white paper aiming to describe the status, the state-of-the art, the challenges and the way
ahead in the area of Content Aware media delivery platforms
A Survey on platoon-based vehicular cyber-physical systems
Vehicles on the road with some common interests can cooperatively form a platoon-based driving pattern, in which a vehicle follows another one and maintains a small and nearly constant distance to the preceding vehicle. It has been proved that, compared to driving individually, such a platoon-based driving pattern can significantly improve the road capacity and energy efficiency. Moreover, with the emerging vehicular adhoc network (VANET), the performance of platoon in terms of road capacity, safety and energy efficiency, etc., can be further improved. On the other hand, the physical dynamics of vehicles inside the platoon can also affect the performance of VANET. Such a complex system can be considered as a platoon-based vehicular cyber-physical system (VCPS), which has attracted significant attention recently. In this paper, we present a comprehensive survey on platoon-based VCPS. We first review the related work of platoon-based VCPS. We then introduce two elementary techniques involved in platoon-based VCPS: the vehicular networking architecture and standards, and traffic dynamics, respectively. We further discuss the fundamental issues in platoon-based VCPS, including vehicle platooning/clustering, cooperative adaptive cruise control (CACC), platoon-based vehicular communications, etc., and all of which are characterized by the tight coupled relationship between traffic dynamics and VANET behaviors. Since system verification is critical to VCPS development, we also give an overview of VCPS simulation tools. Finally, we share our view on some open issues that may lead to new research directions
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Connection Robustness for Wireless Moving Networks Using Transport Layer Multi-homing
Given any form of mobility management through wireless communication, one useful enhancement is improving the reliability and robustness of transport-layer connections in a heterogeneous mobile environment. This is particularly true in the case of mobile networks with multiple vertical handovers. In this thesis, issues and challenges in mobility management for mobile terminals in such a scenario are addressed, and a number of techniques to facilitate and improve efficiency and the QoS for such a handover are proposed and investigated. These are initially considered in an end-to-end context and all protocols and changes happened in the middleware of the connection where the network is involved with handover issues and end user transparency is satisfied.
This thesis begins by investigating mobility management solutions particularly the transport layer models, also making significant observation pertinent to multi-homing for moving networks in general. A new scheme for transport layer tunnelling based on SCTP is proposed. Consequently a novel protocol to handle seamless network mobility in heterogeneous mobile networks, named nSCTP, is proposed. Efficiency of this protocol in relation to QoS for handover parameters in an end-to-end connection while wired and wireless networks are available is considered. Analytically and experimentally it has been proved that this new scheme can significantly increase the throughput, particularly when the mobile networks roam frequently. The detailed plan for the future improvements and expansion is also provided
A network mobility management architecture for a heteregeneous network environment
Network mobility management enables mobility of personal area networks and vehicular networks across heterogeneous access networks using a Mobile Router. This dissertation presents a network mobility management architecture for minimizing the impact of handoffs on the communications of nodes in the mobile network. The architecture addresses mobility in legacy networks without infrastructure support, but can also exploit infrastructure support for improved handoff performance. Further, the proposed architecture increases the efficiency of communications of nodes in the mobile network with counter parts in the fixed network through the use of caching and route optimization. The performance and costs of the proposed architecture are evaluated through empirical and numerical analysis. The analysis shows the feasibility of the architecture in the networks of today and in those of the near future.Verkkojen liikkuuvudenhallinta mahdollistaa henkilökohtaisten ja ajoneuvoihin asennettujen verkkojen liikkuvuuden heterogeenisessÀ verkkoympÀristössÀ kÀyttÀen liikkuvaa reititintÀ. TÀmÀ vÀitöskirja esittÀÀ uuden arkkitehtuurin verkkojen liikkuvuudenhallintaan, joka minimoi verkonvaihdon vaikutuksen pÀÀtelaitteiden yhteyksiin.
Vanhoissa verkoissa, joiden infrastruktuuri ei tue verkkojen liikkuvuutta, verkonvaihdos tÀytyy hallita liikkuvassa reitittimessa. Standardoitu verkkojen liikkuvuudenhallintaprotokolla NEMO mahdollistaa tÀmÀn kÀyttÀen ankkurisolmua kiinteÀssÀ verkossa pakettien toimittamiseen pÀÀtelaitteiden kommunikaatiokumppaneilta liikkuvalle reitittimelle. NEMO:ssa verkonvaihdos aiheuttaa kÀynnissÀ olevien yhteyksien keskeytymisen yli sekunnin mittaiseksi ajaksi, aiheuttaen merkittÀvÀÀ hÀiriötÀ viestintÀsovelluksille.
EsitetyssÀ arkkitehtuurissa verkonvaihdon vaikutus minimoidaan varustamalla liikkuva reititin kahdella radiolla. KÀyttÀen kahta radiota liikkuva reititin pystyy suorittamaan verkonvaihdon keskeyttÀmÀttÀ pÀÀtelaitteiden yhteyksiÀ, mikÀli verkonvaihtoon on riittÀvÀsti aikaa. KÀytettÀvissa oleva aika riippuu liikkuvan reitittimen nopeudesta ja radioverkon rakenteesta. Arkkitehtuuri osaa myös hyödyntÀÀ infrastruktuurin tukea saumattomaan verkonvaihtoon. Verkkoinfrastruktuurin tuki nopeuttaa verkonvaihdosprosessia, kasvattaenmaksimaalista verkonvaihdos tahtia. TÀllöin liikkuva reitin voi kÀyttÀÀ lyhyen kantaman radioverkkoja, joiden solun sÀde on yli 80m, ajonopeuksilla 90m/s asti ilman, ettÀ verkonvaihdos keskeyttÀÀ pÀÀtelaitteiden yhteyksiÀ.
LisÀksi ehdotettu arkkitehtuuri tehostaa kommunikaatiota kÀyttÀen cache-palvelimia liikkuvassa ja kiinteÀssÀ verkossa ja optimoitua reititystÀ liikkuvien pÀÀtelaitteiden ja kiinteÀssÀ verkossa olevien kommunikaatiosolmujen vÀlillÀ. Cache-palvelinarkkitehtuuri hyödyntÀÀ vapaita radioresursseja liikkuvan verkon cache-palvelimen vÀlimuistin pÀivittÀmiseen. HeterogeenisessÀ verkkoympÀristossÀ cache-palvelimen pÀivitys suoritetaan lyhyen kantaman laajakaistaisia radioverkkoja kÀyttÀen. Liikkuvan reitittimen siirtyessÀ laajakaistaisen radioverkon peitealueen ulkopuolelle pÀÀtelaitteille palvellaan sisÀltöÀ, kuten www sivuja tai videota cache-palvelimelta, sÀÀstÀen laajemman kantaman radioverkon rajoitetumpia resursseja.
Arkkitehtuurissa kÀytetÀÀn optimoitua reititystÀ pÀÀtelaitteiden ja niiden kommunikaatiokumppaneiden vÀlillÀ. Optimoitu reititysmekanismi vÀhentÀÀ liikkuvuudenhallintaan kÀytettyjen protokollien langattoman verkon resurssien kulutusta. LisÀksi optimoitu reititysmekanismi tehostaa pakettien reititystÀ kÀyttÀen suorinta reittiÀ kommunikaatiosolmujen vÀlillÀ.
Esitetyn arkkitehtuurin suorituskyky arvioidaan empiirisen ja numeerisen analyysin avulla. Analyysi arvioi arkkitehtuurin suorituskykyÀ ja vertaa sitÀ aikaisemmin ehdotettuihin ratkaisuihin ja osoittaa arkkitehtuurin soveltuvan nykyisiin ja lÀhitulevaisuuden langattomiin verkkoihin.reviewe
Quality-Driven Cross-Layer Protocols for Video Streaming over Vehicular Ad-Hoc Networks
The emerging vehicular ad-hoc networks (VANETs) offer a variety of applications
and new potential markets related to safety, convenience and entertainment, however,
they suffer from a number of challenges not shared so deeply by other types of existing
networks, particularly, in terms of mobility of nodes, and end-to-end quality of service
(QoS) provision. Although several existing works in the literature have attempted to
provide efficient protocols at different layers targeted mostly for safety applications, there remain many barriers to be overcome in order to constrain the widespread use of such networks for non-safety applications, specifically, for video streaming: 1) impact of high
speed mobility of nodes on end-to-end QoS provision; 2) cross-layer protocol design while keeping low computational complexity; 3) considering customer-oriented QoS metrics in the design of protocols; and 4) maintaining seamless single-hop and multi-hop connection between the destination vehicle and the road side unit (RSU) while network is moving.
This thesis addresses each of the above limitations in design of cross-layer protocols for video streaming application. 1) An adaptive MAC retransmission limit selection scheme is proposed to improve the performance of IEEE 802.11p standard MAC protocol for video streaming applications over VANETs. A multi-objective optimization framework, which jointly minimizes the probability of playback freezes and start-up delay of the streamed video at the destination vehicle by tuning the MAC retransmission limit with respect to channel statistics as well as packet transmission rate, is applied at road side unit (RSU). Two-hop transmission is applied in zones in which the destination
vehicle is not within the transmission range of any RSU. In the multi-hop scenario, we
discuss the computation of access probability used in the MAC adaptation scheme and propose a cross-layer path selection scheme; 2) We take advantage of similarity between multi-hop urban VANETs in dense traffic conditions and mesh connected networks. First, we investigate an application-centric routing scheme for video streaming over mesh connected overlays. Next, we introduce the challenges of urban VANETs compared to mesh networks and extend the proposed scheme in mesh network into a protocol for urban VANETs. A classification-based method is proposed to select an optimal path for video streaming over multi-hop mesh networks. The novelty is to translate the path selection
over multi-hop networks to a standard classification problem. The classiïŹcation is based on minimizing average video packet distortion at the receiving nodes. The classifiers are trained offline using a vast collection of video sequences and wireless channel conditions in order to yield optimal performance during real time path selection. Our method substantially reduces the complexity of conventional exhaustive optimization methods and results in high quality (low distortion). Next, we propose an application-centric routing scheme for real-time video transmission over urban multi-hop vehicular ad-hoc network
(VANET) scenarios. Queuing based mobility model, spatial traffic distribution and prob-
ability of connectivity for sparse and dense VANET scenarios are taken into consideration
in designing the routing protocol. Numerical results demonstrate the gain achieved by
the proposed routing scheme versus geographic greedy forwarding in terms of video frame distortion and streaming start-up delay in several urban communication scenarios for various vehicle entrance rate and traïŹc densities; and 3) ïŹnally, the proposed quality-driven
routing scheme for delivering video streams is combined with a novel IP management
scheme. The routing scheme aims to optimize the visual quality of the transmitted video
frames by minimizing the distortion, the start-up delay, and the frequency of the streaming freezes. As the destination vehicle is in motion, it is unrealistic to assume that the vehicle will remain connected to the same access router (AR) for the whole trip. Mobile IP management schemes can beneïŹt from the proposed multi-hop routing protocol in order to adapt proxy mobile IPv6 (PMIPv6) for multi-hop VANET for video streaming applications. The proposed cross-layer protocols can signiïŹcantly improve the video streaming quality in terms of the number of streaming freezes and start-up delay over VANETs while achieving low computational complexity by using pattern classification methods for optimization
Power line communications: an implementation of a real time control architecture for smart grid
Negli ultimi anni Ăš aumentata la presenza di risorse energetiche
distribuite (DERs) nella rete elettrica. La visione della ``rete
intelligente'' (Smart Grid) cerca di introdurre un'infrastruttura di
controllo e di comunicazione di tipo distribuito in modo da sfruttare le potenzialitĂ delle DERs e quindi potenziare e modernizzare la rete di distribuzione attuale. Applicandolo alle reti a bassa tensione, la cosiddetta ``Smart Microgrids'', si Ăš sviluppato un banco di prova (testbed) che permette di dimostrare tecniche di riduzione delle perdite di distribuzione. La soluzione adottata bilancia localmente la potenza reattiva della microgrid attraverso il controllo delle risorse locali ottenendo una riduzione della corrente necessaria per alimentare la rete. Inoltre, vengono analizzati i vantaggi nell'usare la linea elettrica come mezzo di comunicazione e vengono evidenziati alcuni standard di comunicazion
Quality of service and security in future mobile technologies
Future networks will comprise a wide variety of wireless networks. Users will expect to
be always connected from any location, and, as users move, connections will be switched
to available networks using vertical handover techniques.
The current approach of the operators is a centralized network, and the mobility management
is done at the infrastructure level. The decentralized mobility management is
another approach developed in many researches, however, not widely deployed. We are
interested in this type of decentralized mobility management, especially in a highly dynamic
environment when the network topology changes frequently.
We choose a particular case study, Vehicular Ad-hoc Networks (VANETs), which are
a new emerging network technology derived from ad-hoc networks and are an example
of future networks. In the field of Intelligent Transportation Systems (ITS), communications
without a wire between vehicles (V2V) appear as an accident prevention solution
offering a wider vision than conventional sensors. By linking vehicles to telecommunications
network (V2I), new perspectives are offered both passengers and driver with
conventional communication applications such as access Internet, e-learning, games or
chat. This means that future mobile networks like VANETs will have to integrate communications,
mobility, Quality of Service (QoS) and security.
We mainly interested in three issues: mobility, QoS and security. These three issues
are intrinsic to vehicles on motorway networks. We need to simultaneously manage QoS
and security while taking into account users mobility. In this thesis, we propose to contribute
on how to improve security without degrading the quality of service QoS in a
highly mobile environment as VANETs networks. To answer this research question, we
use simulations and experiments. Simulation using Network Simulator 2 (NS2) will be
used to show that security schemes have significant impacts on the throughput QoS, and
our proposed schemes can substantially improve the effective secure throughput with cooperative
communications
Actas da 10ÂȘ ConferĂȘncia sobre Redes de Computadores
Universidade do MinhoCCTCCentro AlgoritmiCisco SystemsIEEE Portugal Sectio
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