Rapid prototyping and fast user trial of multimedia broadcast and cellular services

This paper presents the results of fast user trial of multimedia services that are enabled when a mobile terminal has access to converged services over digital broadcast and mobile telecommunications networks. It first describes the motivations behind developing this system and describes the service scenarios that benefit most from it. It then provides an overview of the service components of the test case scenario. Finally, it presents the results of fast user trials on end users of the services that were developed. This work was conducted as part of the EU-funded CISMUNDUS project

Virgil - Providing Institutional Access to a Repository of Access Grid Sessions

This paper describes the VIRGIL (Virtual Meeting Archival) system which was developed to provide a simple, practical, easy-to-use method for recording, indexing and archiving large scale distributed videoconferences held over Access Grid nodes. Institutional libraries are coming under increasing pressure to support the storage, access and retrieval of such mixed-media complex digital objects in their institutional repositories. Although systems have been developed to record access grid sessions, they don’t provide simple mechanisms for repository ingestion, search and retrieval; and they require the installation and understanding of complex Access Grid tools to record and replay the virtual meetings. Our system has been specifically designed to enable both: the easy construction and maintenance of an archive of Access Grid sessions by managers; and easy search and retrieval of recorded sessions by users. This paper describes the underlying architecture, tools and Web interface we developed to enable the recording, storage, search, retrieval and replay of collaborative Access Grid sessions within a Fedora repository

The Recording of Interactive Media Streams Using a Common Framework

The development of real-time transport protocols for the Internet has been a focus ofresearch for several years. Meanwhile, the Real-Time Transport Protocol (RTP) is a well accepted standard that is widely deployed for the transmission of video and audio streams. The RTP specification, combined with a companion RTP profile, covers common aspects of real-time transmissions of video and audio in various encodings. This enabled the development of RTP recorders which record and play back video and audio streams regardless of a specific media encoding. Interactive media streams with real-time characteristics are now gaining importance rapidly. Examples are the data streams of shared whiteboards, remote Java animations and distributed VRML worlds. In this paper we present a generalized recording service that enables the recording and playback of this new class of media. In analogy to video and audio streams we have defined an RTP profile covering common aspects of the interactive media class. We discuss design principles for this recording ser-vice and describe the key mechanisms that allow to randomly access recorded interactive media streams independent of a specific media type and encoding

VoIP-based Air Traffic Controller Training

Extending VoIP beyond the Internet telephony, we propose a case study of applying the technology outside of its intended domain, to solve a real-world problem. This work is an attempt to understand an analog hardwired communication system of the U.S. Federal Aviation Administration (FAA), and effectively translate it into a generic, standards-based VoIP system that runs on their existing data network. We develop insights into the air traffic training and weigh on the design choices for building a soft real-time data communication system. We also share our real-world deployment and maintenance experiences, as the FAA Academy has been successfully using this VoIP system in five training rooms since 2006 to train the future air traffic controllers of the U.S. and the world

Supporting service discovery, querying and interaction in ubiquitous computing environments.

In this paper, we contend that ubiquitous computing environments will be highly heterogeneous, service rich domains. Moreover, future applications will consequently be required to interact with multiple, specialised service location and interaction protocols simultaneously. We argue that existing service discovery techniques do not provide sufficient support to address the challenges of building applications targeted to these emerging environments. This paper makes a number of contributions. Firstly, using a set of short ubiquitous computing scenarios we identify several key limitations of existing service discovery approaches that reduce their ability to support ubiquitous computing applications. Secondly, we present a detailed analysis of requirements for providing effective support in this domain. Thirdly, we provide the design of a simple extensible meta-service discovery architecture that uses database techniques to unify service discovery protocols and addresses several of our key requirements. Lastly, we examine the lessons learnt through the development of a prototype implementation of our architecture

Performance analysis of a caching algorithm for a catch-up television service

The catch-up TV (CUTV) service allows users to watch video content that was previously broadcast live on TV channels and later placed on an on-line video store. Upon a request from a user to watch a recently missed episode of his/her favourite TV series, the content is streamed from the video server to the customer's receiver device. This requires that an individual flow is set up for the duration of the video, and since it is hard to impossible to employ multicast streaming for this purpose (as users seldomly issue a request for the same episode at the same time), these flows are unicast. In this paper, we demonstrate that with the growing popularity of the CUTV service, the number of simultaneously running unicast flows on the aggregation parts of the network threaten to lead to an unwieldy increase in required bandwidth. Anticipating this problem and trying to alleviate it, the network operators deploy caches in strategic places in the network. We investigate the performance of such a caching strategy and the impact of its size and the cache update logic. We first analyse and model the evolution of video popularity over time based on traces we collected during 10 months. Through simulations we compare the performance of the traditional least-recently used and least-frequently used caching algorithms to our own algorithm. We also compare their performance with a "perfect" caching algorithm, which knows and hence does not have to estimate the video request rates. In the experimental data, we see that the video parameters from the popularity evolution law can be clustered. Therefore, we investigate theoretical models that can capture these clusters and we study the impact of clustering on the caching performance. Finally, some considerations on the optimal cache placement are presented

Automatic subscriptions in publish-subscribe systems

In this paper, we describe how to automate the process of subscribing to complex publish-subscribe systems. We present a proof-of-concept prototype, in which we analyze Web browsing history to generate zero-click subscriptions to Web feeds and video news stories. Our experience so far indicates that user attention data is a promising source of data for automating the subscription process