NUSAT update

This paper presents, in general terms, the results of the experiments with NUSAT I. These include what has been learned about the strengths of the original design, as well as improvements being incorporated into NUSAT II, which should be of interest to designers of future Get Away Special ejected satellites. This paper also presents an account of the formation of the Center for AeroSpace Technology (CAST) at Weber State College, which grew out of the NUSAT project, and some potential applications and markets for inexpensive, low orbit satellites which CAST has explored

On the use of Satellite Television in High Energy Physics

This paper assesses the feasibility of exploiting commercial satellite television technologies to broadcast video signals and data from major High Energy Physics facilities to collaborating institutes throughout the world.Comment: Invited talk at CHEP'98, Chicago, USA, August 31 - September 4, 199

Using Intelligent Prefetching to Reduce the Energy Consumption of a Large-scale Storage System

Many high performance large-scale storage systems will experience significant workload increases as their user base and content availability grow over time. The U.S. Geological Survey (USGS) Earth Resources Observation and Science (EROS) center hosts one such system that has recently undergone a period of rapid growth as its user population grew nearly 400% in just about three years. When administrators of these massive storage systems face the challenge of meeting the demands of an ever increasing number of requests, the easiest solution is to integrate more advanced hardware to existing systems. However, additional investment in hardware may significantly increase the system cost as well as daily power consumption. In this paper, we present evidence that well-selected software level optimization is capable of achieving comparable levels of performance without the cost and power consumption overhead caused by physically expanding the system. Specifically, we develop intelligent prefetching algorithms that are suitable for the unique workloads and user behaviors of the world\u27s largest satellite images distribution system managed by USGS EROS. Our experimental results, derived from real-world traces with over five million requests sent by users around the globe, show that the EROS hybrid storage system could maintain the same performance with over 30% of energy savings by utilizing our proposed prefetching algorithms, compared to the alternative solution of doubling the size of the current FTP server farm

What's Going on in Community Media

What's Going On in Community Media shines a spotlight on media practices that increase citizen participation in media production, governance, and policy. The report summarizes the findings of a nationwide scan of effective and emerging community media practices conducted by the Benton Foundation in collaboration with the Community Media and Technology Program of the University of Massachusetts, Boston. The scan includes an analysis of trends and emerging practices; comparative research; an online survey of community media practitioners; one-on-one interviews with practitioners, funders and policy makers; and the information gleaned from a series of roundtable discussions with community media practitioners in Boston, Chicago, Minneapolis/St. Paul, and Portland, Oregon

A cross-layer approach to enhance QoS for multimedia applications over satellite

The need for on-demand QoS support for communications over satellite is of primary importance for distributed multimedia applications. This is particularly true for the return link which is often a bottleneck due to the large set of end-users accessing a very limited uplink resource. Facing this need, Demand Assignment Multiple Access (DAMA) is a classical technique that allows satellite operators to offer various types of services, while managing the resources of the satellite system efficiently. Tackling the quality degradation and delay accumulation issues that can result from the use of these techniques, this paper proposes an instantiation of the Application Layer Framing (ALF) approach, using a cross-layer interpreter(xQoS-Interpreter). The information provided by this interpreter is used to manage the resource provided to a terminal by the satellite system in order to improve the quality of multimedia presentations from the end users point of view. Several experiments are carried out for different loads on the return link. Their impact on QoS is measured through different application as well as network level metrics

Global meteorological data facility for real-time field experiments support and guidance

A Global Meteorological Data Facility (GMDF) has been constructed to provide economical real-time meteorological support to atmospheric field experiments. After collection and analysis of meteorological data sets at a central station, tailored meteorological products are transmitted to experiment field sites using conventional ground link or satellite communication techniques. The GMDF supported the Global Tropospheric Experiment Amazon Boundary Layer Experiment (GTE-ABLE II) based in Manaus, Brazil, during July and August 1985; an arctic airborne lidar survey mission for the Polar Stratospheric Clouds (PSC) experiment during January 1986; and the Genesis of Atlantic Lows Experiment (GALE) during January, February and March 1986. GMDF structure is similar to the UNIDATA concept, including meteorological data from the Zephyr Weather Transmission Service, a mode AAA GOES downlink, and dedicated processors for image manipulation, transmission and display. The GMDF improved field experiment operations in general, with the greatest benefits arising from the ability to communicate with field personnel in real time

Beyond Infrastructure: Broadband for Development in Remote and Indigenous Regions

Recent telecommunications stimulus projects in the U.S. and Canada were intended to increase availability of broadband through funding infrastructure investments, largely in rural and remote regions. However, true access involves more than availability; it also includes affordability and adoption. This paper presents a framework for analyzing broadband adoption that takes into consideration geographical, economic and cultural environments in indigenous communities. It includes an overview of potential social and economic impacts of broadband in remote areas, using examples from the Alaska study and the Canadian North. It then reports on results of an evaluation of Internet use and potential adoption of broadband in remote indigenous communities of southwest Alaska. Finally, the paper provides a comparative analysis of U.S. and Canadian policies intended to achieve affordable access to broadband for rural users and sustainable business models for rural broadband providers.Ye

On the Trade-off Between Spectrum Efficiency with Dedicated Access and Short End-to-End Transmission Delays with Random Access in DVB-RCS2

This paper analyses the performance of TCP over random and dedicated access methods in the context of DVB-RCS2. Random access methods introduce a lower connection delay compared to dedicated methods. We investigate the potential to improve the performance of short flows in regards to transmission delay, over random access methods for DVB-RCS2 that is currently under development. Our simulation experiments show that the transmission of the first ten IP datagrams of each TCP flow can be 500 ms faster with random access than with dedicated access making the former of interest to carry Internet traffic. Such methods, however, are less efficient in regards to bandwidth usage than dedicated access mecanisms and less reliable in overloaded network conditions. Two aspects of channel usage optimization can be distinguished: reducing the duration of ressource utilization with random access methods, or increasing the spectrum efficiency with dedicated access methods. This article argues that service providers may let low-cost users exploit the DVB-RCS2 to browse the web by introducing different services, which choice is based on the channel access method

Toward Universal Broadband in Rural Alaska

The TERRA-Southwest project is extending broadband service to 65 communities in the Bristol Bay, Bethel and Yukon-Kuskokwim regions. A stimulus project funded by a combination of grants and loans from the Rural Utilities Service (RUS), TERRA-Southwest has installed a middle-mile network using optical fiber and terrestrial microwave. Last-mile service will be through fixed wireless or interconnection with local telephone networks. The State of Alaska, through its designee Connect Alaska, also received federal stimulus funding from the National Telecommunications and Information Administration (NTIA) for tasks that include support for an Alaska Broadband Task Force “to both formalize a strategic broadband plan for the state of Alaska and coordinate broadband activities across relevant agencies and organizations.” Thus, a study of the impact of the TERRA project in southwest Alaska is both relevant and timely. This first phase provides baseline data on current access to and use of ICTs and Internet connectivity in rural Alaska, and some insights about perceived benefits and potential barriers to adoption of broadband. It is also intended to provide guidance to the State Broadband Task Force in determining how the extension of broadband throughout the state could contribute to education, social services, and economic activities that would enhance Alaska’s future. Results of the research could also be used proactively to develop strategies to encourage broadband adoption, and to identify applications and support needed by users with limited ICT skills.Connect Alaska. The National Telecommunications and Information Administration. General Communications Incorporated.Part 1: An Analysis of Internet Use in Southwest Alaska / Introduction / Previous Studies / Current Connectivity / Analytical Framework and Research Methodology / Demographics / Mobile Phones: Access and Use / Access to the Internet / Internet Useage / Considerations about Internet Service / Interest in Broadband / Sources of News / Comparison with National Data / Internet Use by Businesses and Organizations / What Difference may Broadband make in the Region? / Conclusiongs / Part 2 Literature Review / Reference