Adding Policy-based Control to Mobile Hosts Switching between Streaming Proxies

We add a simple policy-based control component to mobile hosts that enables them to control the continuous reception of live multimedia content (e.g. a TV broadcast) while they switch between different distributors of that content. Policy-based control provides a flexible means to automate the switching behavior of mobile hosts. The policies react to changes in the mobile host's environment (e.g. when a hotspot network appears) and determine when and how to invoke an earlier developed application-level protocol to discover the capabilities (e.g. supported encodings) of the content distributors and to execute the switches. The design of the control component is based on the IETF policy model, but extended and applied at the application-level instead of at the network-level. We implemented the system and deployed it in a small-scale test bed

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 aggregator�s 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 �best� 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 SDP�s offer-answer model in a novel way

REMOTE - Everything you always wanted to know about the Internet (but were afraid to ask) - Research and Education Networking from pioneering to path finding

Please note the unusual starting time. This lecture will start at 10:00 instead of 11:00. ABSTRACT: You think you know how the internet works, but do you really understand the complexity of today’s pervasive internet or do you think of it simply as a scaled up version of the Arpanet just after TCP/IP was introduced? If you aren’t sure what an ASN is or what MPLS does then these lectures are for you. Although our speakers will cover how the internet was born—and touch on the role that institutes such as CERN played in its development—the focus will be on the technologies, both hardware and software, that enable interconnect billions of devices and move exabytes of data. Even if you do know what an ASN is and understand MPLS, you’re be bound to learn something as these experts explain the rules and standards that regulate these technologies and how they are created and agreed. BIO: Since July 2017 Erik Huizer is the CEO for GÉANT, Europe's leading collaboration on e-infrastructure and services for research and education. Before that he was CTO at SURFnet, the Dutch national academic and research network. From 2008 - 2012 Erik Huizer was Managing Director (Algemeen Directeur) for the Information Sciences and Space technology division at TNO (The Netherlands organization for applied scientific research). From 1988 - 2000 Erik also worked at SURFnet and he chaired various RARE (later Terena) WGs. He was a member of the Terena technical committee. From 2000 - 2015 he was a part time Professor Internet Applications. Most recently at Utrecht University and before that at the faculty of computer science of the University Twente. He remains a research associate at Utrecht University. For over 30 years he has been involved in education and research networking, Internet standardization and Internet governance. In the nineties he was Area Director for Applications of the Internet Engineering Task Force (IETF), and a member of the Internet Engineering Steering Group (IESG). From 1995 till 1999 member of the Internet Architecture Board. Responsible for restructuring of the Internet standards process (IETF). From 1999 till 2001 Chair of the Internet Research task force. From 2001 onwards, he had various roles in ICANN and IGF. Erik chaired the Dutch IPv6 Taskforce from 2002-2017. The taskforce created awareness, build technical capacity and helped ISPs, SMEs and the government to introduce IPv6 in the Netherlands. For his contributions to the Internet he has been inducted into the Internet Hall of Fame in 2014. In 2015 he was honored with the title of Dutch ICT personality of the year. He has been teaching at various developing countries workshops on Internet policy and technology. He is a TEDx speaker. &nbsp; GÉANT GÉANT is the organization that serves the European NRENs and, through them, their constituencies: institutions for Research and Education. GÉANT with its community develops, innovates and operates a pan-European network for scientific excellence, research and education. Through its integrated catalogue of connectivity, collaboration and identity services, GÉANT provides users with highly reliable, unconstrained access to computing, analysis, storage, applications and other resources, to ensure that Europe remains at the forefront of research. Through interconnections with its 38 National Research and Education Network (NREN) partners, the GÉANT network is the largest and most advanced R&amp;E network in the world, connecting over 50 million users at 10,000 institutions across Europe and supporting all scientific disciplines. The backbone network operates at speeds of up to 1 Tbps and reaches over 100 national networks worldwide. Since its establishment over 20 years ago, the GÉANT network has developed progressively to ensure that European researchers lead international and global collaboration. Over 5 petabytes of data is transferred via the GÉANT IP backbone every day. More than just an infrastructure for e-science, it stands as a positive example of European integration and collaboration. GÉANT develops, delivers and promotes advanced networks and associated e-infrastructure services. GEANT supports open innovation, collaboration and knowledge-sharing amongst its members, partners and the wider research and education networking community. www.geant.org</p

Understanding the diffusion of HDTV through an analysis of risks and uncertainties of supply and demand in the netherlands

This paper analyses the diffusion of HDTV in The Netherlands. The research provides an analysis of the supply side of the broadcast value chain as well as an analysis of consumer acceptance of HDTV in The Netherlands. The research is part of longitudinal research effort and uses both qualitative and quantitative measures. Using risks and uncertainties as a broad theoretical basis, we conclude that the consequence of the reluctant attitude on the supply side leads to a lack of knowledge on the demand side which is a necessary condition for the adoption of HDTV by consumers. This deadlock can be overcome when the supply side starts taking some calculated risks

Understanding technology adoption through individual and context characteristics: the case of HDTV

Technology adoption research has a tradition of using and improving Davis' (1989) “Technology Acceptance Model” (TAM) and extended versions of it. This article suggests a break with this tradition by showing that the TAM is limited in its understanding of technology adoption. Two alternative approaches are proposed that focus on the role of knowledge and user-technology match, and on the role of temporary dynamical contexts in the process of adoption decision-making. Together with the TAM, both approaches were empirically tested and compared to the TAM by incorporating them in a questionnaire regarding the adoption intention of HDTV in the Netherlands. Results show that the constructs of both approaches show significant relations with the respondents' adoption intentions of HDTV and, together, offer a good alternative to the TAM. This result can be seen as a basis for more future research that uses technological and contextual factors as a starting point for adoption research. Using this starting point will contribute to a better understanding of future technology adoption processes

Ca2+ cycling in cardiomyocytes from a high-performance reptile, the varanid lizard (Varanus exanthematicus)

The Session Initiation Protocol (SIP) is a popular application-level signaling protocol that is used for a wide variety of applications such as session control and mobility handling. In some of these applications, the exchange of SIP messages is time-critical, for instance when SIP is used to handle mobility for voice over IP sessions. SIP may however introduce significant delays when it runs on top of UDP over lossy (wireless) links. These delays are the result of the exponential back-off retransmission scheme that SIP uses to recover from packet loss, which has a default back-off time\ud of half a second.\ud In this paper, we empirically investigate the delay introduced by SIP when it runs on top of UDP over IEEE 802.11b links. We focus on the operation of SIP at the edge of an 802.11b cell (e.g., to update a mobile host�s IP address after a handoff) as this is where SIP�s retransmissions scheme is most likely to come into play. We experiment with a few 802.11 parameters that influence packet loss on the wireless link, pecifically with different link-level retransmission thresholds, signal-to-noise-ratios (SNRs), and\ud amounts of background traffic. We conduct these experiments in a controlled environment that is free from interfering 802.11 sources.\ud Our results indicate that (1) SIP usually introduces little delay except for an SNR range of a few dBs at the very edge of an 802.11 cell in which the delay increases sharply, and (2) that a maximum of four 802.11 retransmissions suffices to limit the delay introduced by SIP retransmissions. The first result is of interest to developers of\ud SIP applications who have to decide at which SNR to initiate a handoff to another network. The second result allows network providers to optimize their 802.11b networks for delay sensitive SIP applications

Application-level Policies for Automatic Switching between Content Redistributors

We consider the distribution of live and scheduled multimedia content (e.g., radio or TV broadcasts) through multiple aggregators. An aggregator is an access-controlled redistributor that operates a pool of proxy servers to aggregate content from source content providers and forward it to mobile hosts. Aggregators package content into channels (e.g., BBC 9 o�clock news) and offer them at various quality levels (e.g., using different encodings) and prices. Mobile hosts receive channels via a �beyond 3G� wireless Internet, which consists of different types of wireless networks (e.g., 802.11 and UMTS networks).\ud In this paper, we investigate how a mobile host can switch to another aggregator and an associated quality level while it is receiving a channel. This situation can for instance occur when a mobile host roams into a (different type of) wireless network through which a new aggregator is available, or when the mobile host roams out of a network while its current aggregator is only available through that network. We use an earlier developed application-level protocol that enables mobile hosts to discover accessible aggregators and to switch to one of them. We propose a complementary control component that automatically matches the user�s preferences (e.g., regarding cost or quality) with the aggregators� available quality levels and the capabilities of the wireless networks the mobile host can connect to. The control component uses policies to decide when to invoke the protocol to hunt for alternative aggregators, how to rate their quality levels based on the user�s preferences, and when and how to switch to another aggregator. Together, the protocol and the control component ensure service continuity without bothering the user. We present the design of the system and its prototype deployed in a small-scale test bed