638 research outputs found
Delivering Live Multimedia Streams to Mobile Hosts in a Wireless Internet with Multiple Content Aggregators
We consider the distribution of channels of live multimedia content (e.g., radio or TV broadcasts) via multiple content aggregators. In our work, an aggregator receives channels from content sources and redistributes them to a potentially large number of mobile hosts. Each aggregator can offer a channel in various configurations to cater for different wireless links, mobile hosts, and user preferences. As a result, a mobile host can generally choose from different configurations of the same channel offered by multiple alternative aggregators, which may be available through different interfaces (e.g., in a hotspot). A mobile host may need to handoff to another aggregator once it receives a channel. To prevent service disruption, a mobile host may for instance need to handoff to another aggregator when it leaves the subnets that make up its current aggregatorïżœs service area (e.g., a hotspot or a cellular network).\ud
In this paper, we present the design of a system that enables (multi-homed) mobile hosts to seamlessly handoff from one aggregator to another so that they can continue to receive a channel wherever they go. We concentrate on handoffs between aggregators as a result of a mobile host crossing a subnet boundary. As part of the system, we discuss a lightweight application-level protocol that enables mobile hosts to select the aggregator that provides the ïżœbestïżœ configuration of a channel. The protocol comes into play when a mobile host begins to receive a channel and when it crosses a subnet boundary while receiving the channel. We show how our protocol can be implemented using the standard IETF session control and description protocols SIP and SDP. The implementation combines SIP and SDPïżœs offer-answer model in a novel way
A Cross-System Approach for Multimedia Services with IP Multicast in 4G Networks
The increased demand for multimedia services by mobile end users in recent years have driven both Broadcast and Wireless Network operators to develop new systems and architectures for the deployment of such services. The proposed solutions are nonetheless limited either in terms of QoS or Capabilities to deliver new interactive services. This paper highlights strengths and drawbacks of the existing technologies in terms of QoS, Security and Mobility. In order to fill the gap between current solutions we propose a new architecture that builds itself on the synergies created by a heterogeneous network made of existing delivering technologies, such as 3GPP/MBMS and DVB, where services can be delivered to end-users in the most appropriate way for end-users and operators alike. A prototype implementation is further described.EU project - IST-2002- 506997 Daidalos I
Overview of evolved Multimedia Broadcast Multicast Services (eMBMS)
MBMS was introduced as a service to optimize the dissemination of common interest multimedia content. Recently, it evolved to eMBMS based on LTE-centered flexibilities. However, launch of eMBMS over LTE may support new services e.g. pushed content for M2M services and delivery of premium content to the users enjoying secured QoS. This document primarily focusses on the rules, procedures and architecture supporting MBMS based data exchanges, which have not seen any major changes since Release 9
Key distribution technique for IPTV services with support for admission control and user defined groups
Tese de doutoramento. Engenharia Electrotécnica e de Computadores. Faculdade de Engenharia. Universidade do Porto. 200
Requirements of a middleware for managing a large, heterogeneous programmable network
Programmable networking is an increasingly popular area of research in both industry and academia. Although most programmable network research projects seem to focus on the router architecture rather than on issues relating to the management of programmable networks, there are numerous research groups that have incorporated management middleware into the programmable network router software. However, none seem to be concerned with the effective management of a large heterogeneous programmable network. The requirements of such a middleware are outlined in this paper. There are a number of fundamental middleware principles that are addressed in this paper; these include management paradigms, configuration delivery, scalability and transactions. Security, fault tolerance and usability are also examinedâalthough these are not essential parts of the middleware, they must be addressed if the programmable network management middleware is to be accepted by industry and adopted by other research projects
Nap: Practical Micro-Sleeps for 802.11 WLANs
In this paper, we revisit the idea of putting interfaces to sleep during
'packet overhearing' (i.e., when there are ongoing transmissions addressed to
other stations) from a practical standpoint. To this aim, we perform a robust
experimental characterisation of the timing and consumption behaviour of a
commercial 802.11 card. We design Nap, a local standard-compliant
energy-saving mechanism that leverages micro-sleep opportunities inherent to
the CSMA operation of 802.11 WLANs. This mechanism is backwards compatible and
incrementally deployable, and takes into account the timing limitations of
existing hardware, as well as practical CSMA-related issues (e.g., capture
effect). According to the performance assessment carried out through
trace-based simulation, the use of our scheme would result in a 57% reduction
in the time spent in overhearing, thus leading to an energy saving of 15.8% of
the activity time.Comment: 15 pages, 12 figure
End-to-end security in active networks
Active network solutions have been proposed to many of the problems caused by the increasing heterogeneity of the Internet. These ystems allow nodes within the network to process data passing through in several ways. Allowing code from various sources to run on routers introduces numerous security concerns that have been addressed by research into safe languages, restricted execution environments, and other related areas. But little attention has been paid to an even more critical question: the effect on end-to-end security of active flow manipulation. This thesis first examines the threat model implicit in active networks. It develops a framework of security protocols in use at various layers of the networking stack, and their utility to multimedia transport and flow processing, and asks if it is reasonable to give active routers access to the plaintext of these flows. After considering the various security problem introduced, such as vulnerability to attacks on intermediaries or coercion, it concludes not. We then ask if active network systems can be built that maintain end-to-end security without seriously degrading the functionality they provide. We describe the design and analysis of three such protocols: a distributed packet filtering system that can be used to adjust multimedia bandwidth requirements and defend against denial-of-service attacks; an efficient composition of link and transport-layer reliability mechanisms that increases the performance of TCP over lossy wireless links; and a distributed watermarking servicethat can efficiently deliver media flows marked with the identity of their recipients. In all three cases, similar functionality is provided to designs that do not maintain end-to-end security. Finally, we reconsider traditional end-to-end arguments in both networking and security, and show that they have continuing importance for Internet design. Our watermarking work adds the concept of splitting trust throughout a network to that model; we suggest further applications of this idea
Linux-Box: DVB and VoD streaming over local area networks
Aquest treball tracta sobre un projecte comĂș anomenat Linux-Box portat a terme per diferents persones al departament de Telecomunicacions (IET) de la Universitat de Pisa. Linux-Box Ă©s un sistema dotat amb targetes TDT (DVB-T) i de televisiĂł per satĂšl·lit (DVB-S) que permet transmetre aquests senyals fins a un Ă mbit domĂšstic. MĂ©s endavant podria ser utilitzat en Ă mbits privats com les cases de clients o en institucions pĂșbliques com escoles, universitats, biblioteques i tambĂ© seria possible en Ă mbits empresarials. El projecte estĂ dividit en 4 apartats:
1. Ubuntu 6.06 LTS. Explica perquĂš sâutilitza Ubuntu en el projecte. A mĂ©s
tambĂ© sâexplica de forma breu que Ă©s Linux i les distribucions mĂ©s utilitzades.
2. Multimedia Network Protocols: sâexpliquen els diferents protocols desde la capa de xarxa fins la capa dâaplicaciĂł que sâutilitzen en el projecte Linux-Box.
Aquests protocols sĂłn utilitzats tant en streaming, com en anunciaciĂł,
unicast/multicast, encapsulat de vĂdeo i codecs. Els diversos temes tractats aquĂ
es fan amb el propĂČsit de comparar i no nomĂ©s com a recerca teĂČrica. A la fi es
veuen els programes utilitzats en el projecte per analitzar el trĂ fic de la xarxa.
3. Linux-Box: sâexplica el funcionament i els objectius globals del projecte. Es
dedica un sub-apartat a âVideoLan - VLCâ part important a nivell de sofware. MĂ©s
endavant es parla de les caracterĂstiques de la Linux-Box de forma acurada:
streaming de VoD i senyals de TV i sâanalitzen els problemes coneguts i les
seves solucions proposades. A la fi sâenumeren els llenguatges de programaciĂł
utilitzats al projecte i en quina part sâutilitzen. Observarem que Ă©s una aplicaciĂł
on diversos llenguatges de programaciĂł estan contĂnuament solapats.
4. Developed Part: es posa en prĂ ctica la teoria estudiada a la resta del treball.
EstĂ dividida en 4 seccions:
Desenvolupar una aplicaciĂł en codi C per convertir la llista de Canals
(tant terrestre com de satÚl·lit) en format XML.
Una secciĂł dedicada al streaming de Canals de TV a la pĂ gina web principal.
Un anĂ lisis profund dels paquets creats per la Linux-Box i la seva activitat a la xarxa.
Finalment sâanalitzen els diferents scripts i les seves configuracions.
Alguns sĂłn Ăștils per a un futur desenvolupament i dâaltres sâutilitzen en
seccions prĂšvies.
5. Conclusions: contĂ© les conclusions i lĂnies futures. El projecte compta amb
diverses opcions que encara poden ser implementades i estudiades. AquĂ
exposem les nostres interpretacions i possibles lĂnies futures dâestudi
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