| 1. |
- Doolin, Kevin, et al.
(author)
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Context-Aware Multimedia Services in a Pervasive Environment : The Daidalos Approach
- 2008
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In: Proceedings of the 2008 Ambi-Sys workshop on Software Organisation and MonIToring of Ambient Systems. - : ICST. - 9789639799165
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Conference paper (peer-reviewed)abstract
- There is a clear trend towards making multimedia applications context-aware so as to customize them by taking into account any collection of information which may be relevant, such as e.g. user location. However, current multimedia services are dominated by IMS, which is seen as a service platform that uses the SIP protocol to access all services that the internet can provide. In this paper, we describe the Daidalos approach on making IMS based multi-media services context-aware. We also demonstrate, how generic sensor networks can be integrated into the context management system of our platform thus enabling sensor network detected events to influence behavior of context-aware multimedia applications
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| 2. |
- Guenkova-Luy, Teodora, et al.
(author)
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A Session-Initiation-Protocol-based Middleware for Multi-Application Management
- 2007
-
Conference paper (peer-reviewed)abstract
- The deployment of multimedia services in next-generation networks is a challenge due to the high configuration complexity of the streaming process in different stationary and mobile sub-networks and for various user devices. The Session Initiation Protocol (SIP) has proven to be a suitable mechanism to handle the control of multimedia services in such networks. However, the current standardization and implementation of SIP do not allow the simultaneous coordination of multiple concurrent applications on a single device, as the prescribed realization of the SIP state machines (transactions) does not consider mutual access of applications to a single SIP stack. This paper presents a SIP-based mechanism for synchronized management of services in a shared environment. We have developed a middleware that facilitates the uniform access of multiple applications towards one or multiple SIP stacks to enable prioritization of services and centralized resource coordination of concurrent SIP applications on a single terminal or server
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| 3. |
- Guenkova-Luy, Teodora, et al.
(author)
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Advanced Multimedia Management Control Model and Content Adaptation
- 2006
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Conference paper (peer-reviewed)abstract
- The delivery and adaptation of multimedia content in distributed and heterogeneous environments requires flexible control and management mechanisms in terminals and in control entities inside the network. In the near future, it is important to reach interoperability between the IETF approaches on multimedia session establishment and control and the MPEG-21 efforts for multimedia streaming and adaptation to bring advanced multimedia service provisioning and adaptation services towards the customer. MPEG-21 Digital Item Adaptation (DIA) provides normative descriptions for supporting adaptation of multimedia content, but does not define interactions with transport and control mechanisms. On the other hand, the IETF standardization efforts on multimedia session control provide the necessary transport (e.g. RTP) and control mechanisms (SDP/SDPng). We thus bridge the gap between those approaches by creating a converged XML model that enables the integration of session management and negotiation protocols (e.g. SIP or Megaco) inspired by the XML formats of MPEG-21 DIA and SDPng. We also present preliminary implementation results of the converged model along with concepts and implementation of network-based content adaptation mechanisms through media gateways that enable flexible multimedia management for heterogeneous consumer terminals
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| 4. |
- Kassler, Andreas, et al.
(author)
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Network-Based Content Adaptation of Streaming Media Using MPEG-21 DIA and SDPng
- 2006
-
Conference paper (peer-reviewed)abstract
- The dynamic adaptation of multimedia content in distributed heterogeneous environments is a key enabler for next generation ubiquitous and pervasive services. Systems implementing the Universal Multimedia Access (UMA) approaches are predominantly combinations of MPEG-centric and/or proprie-tary solutions. However, it is important to reach interoperability between the IETF approach for multimedia-session establish-ment and control and the MPEG-21 efforts for metadata-driven adaptation, in order to enable personalized multimedia delivery for ubiquitous users, where media is delivered and adapted on the fly taking into account context and environment. In this pa-per, we present a format-independent model that enables con-verging IETF and MPEG-21 descriptions for streaming media. We introduce the architecture of a multimedia stream-adaptation service to enable communication between terminals having het-erogeneous capabilities and communicating over heterogeneous networks. We demonstrate how the service utilizes the converged session description model and how it can be deployed inside special adaptation nodes within any part of the network to enable dynamic content adaptation both at the terminal and within the network
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| 5. |
- Schorr, Andreas, et al.
(author)
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Description and Lookup of Media-Stream Adaptation Services
- 2006
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Conference paper (peer-reviewed)abstract
- In this paper, we propose a new application of RDF that enables the description of services offered by so-called media-stream adaptation nodes (MSANs). An MSAN can manipulate a stream by changing media format and quality on-the-fly during an ongoing streaming process. An accurate description of the offered services is necessary, because different clients may have very specific requirements that cannot be fulfilled by every MSAN. In this paper, we propose an RDF-based vocabulary that enables an MSAN to provide such an accurate description of its services. We also demonstrate how clients can formulate search queries to find a services provider that fulfills their specific requirements
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| 6. |
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| 7. |
- Szwabe, Andrzej, et al.
(author)
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Dynamic Multimedia Stream Adaptation and Rate Control for Heterogeneous Networks
- 2006
-
Conference paper (peer-reviewed)abstract
- : Dynamic adaptation of multimedia content is seen as an important feature of next generation networks and pervasive systems to enable terminals and applications to adapt to changes in e.g. context, access network, and available QoS due to mobility of users, devices or sessions. We present the architecture of a multimedia stream adaptation service which enables communication between terminals having heterogeneous hard- and software capabilities and served by heterogeneous networks. The service runs on special content adaptation nodes which can be placed at any location within the network. The flexible structure of our architecture allows using a variety of different adaptation engines. A generic transcoding engine is used to change the codec of streams. An MPEG-21 DIA based transformation engine allows adjusting the data rate of scalable media streams. An intelligent decision-taking engine implements adaptive flow control which takes into account current network QoS parameters and congestion information. Measurements demonstrate the quality gains achieved through adaptive congestion control mechanisms under conditions typical for a heterogeneous network
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| 8. |
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| 9. |
- Ali Yahiya, Tara, et al.
(author)
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Seamless Interworking of WLAN and WMAN Wireless Networks
- 2006
-
Conference paper (peer-reviewed)abstract
- Future network environments will be heterogeneous and mobile terminals will have the opportunity to dynamically select among many different access technologies. Therefore, it is important to provide service continuity in case of vertical handovers when terminals change the access technology. Two important wireless access technologies are WLAN (Wireless Local Access Networks) and WMAN (Wireless Metropolitan Access Networks) networks. In this paper, we address several challenges related to a seamless integration of those technologies. We highlight important aspects for designing a WLAN/WMAN interworking architecture and we address important Quality of Service (QoS) issues for such interworked systems like degree of QoS support provided by the technologies, QoS mapping and signalling for vertical handover. By formulating several interworking scenarios, where WLAN users with ongoing voice, video and data sessions hand over to WMAN, we study QoS and performance issues and analyse feasibility of seamless session continuity through simulations
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| 10. |
- Bayer, Nico, et al.
(author)
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VoIP service performance optimization in pre-IEEE 802.11s Wireless Mesh Networks
- 2008
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In: Proceedings of the IEEE International Conference on Circuits andSystems for Communications (ICCSC) 2008. - : IEEE conference proceedings. - 9781424417070 ; , s. 75-79
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Conference paper (peer-reviewed)abstract
- 802.11-based wireless mesh networks are seen as a means for providing last mile connections to next generation networks. Due to the low deployment cost and the mature technology used, they are scalable, easy to implement and robust. With an increasing coverage of wireless networks, VoIP becomes a cheaper alternative for traditional and cellular telephony. In this paper, we carry out a feasibility study of VoIP in a dual radio mesh environment. Heading towards 802.11s, we present the design of a mesh testbed and methodology for performing the measurements. Additionally, we address the problem that small voice packets introduce a high overhead leading to a low voice capacity of 802.11 based mesh networks. In order to alleviate this problem and increase the voice capacity, a novel packet aggregation mechanism is presented and evaluated using the ns-2 simulator.
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