1,986 research outputs found

    Multicast Mobility in Mobile IP Version 6 (MIPv6) : Problem Statement and Brief Survey

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    Integration of Mission Control System, On-board Computer Core and spacecraft Simulator for a Satellite Test Bench: Integration of Mission Control System,On-board Computer Core and spacecraft Simulator for a Satellite Test Bench

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    The satellite avionics platform has been developed in cooperation with Airbus and is called „Future Low-cost Platform“ (FLP). It is based on an Onboard Computer (OBC) with redundant processor boards based on SPARC V8 microchips of type Cobham Aeroflex UT699. At the University of Stuttgart a test bench with a real hardware OBC and a fully simulated satellite is available for testing real flight scenarios with the Onboard Software (OBSW) running on representative hardware. The test bench as later the real flying satellite "Flying Laptop" – is commanded from a real Ground Control Centre (GCC). The main challenges in the FLP project were - Onboard computer design, - Software design and - Interfaces between platform and payloads In the course of industrialization of this FLP platform technology for later use in satellite constellations, Airbus has started to set up an in-house test bench where all the technologies shall be developed. The initial plan is to get first core elements of the FLP OBSW ported to the new dual-core processor and the new Space Wire(SpW) routing network. The plan also has an inclusion of new Mission Control Software with which one can command the OBC. The new OBC has a dual core processor Cobham Gaisler GR712 and hence, all the payload and related functionality are to be implemented only in a second core which involves a lot of low-level task distribution. The consequent SpW router network application and dual-core platform/payload OBSW sharing are entirely new in the field of satellite engineering

    QoS Provisioning in Converged Satellite and Terrestrial Networks: A Survey of the State-of-the-Art

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    It has been widely acknowledged that future networks will need to provide significantly more capacity than current ones in order to deal with the increasing traffic demands of the users. Particularly in regions where optical fibers are unlikely to be deployed due to economical constraints, this is a major challenge. One option to address this issue is to complement existing narrow-band terrestrial networks with additional satellite connections. Satellites cover huge areas, and recent developments have considerably increased the available capacity while decreasing the cost. However, geostationary satellite links have significantly different link characteristics than most terrestrial links, mainly due to the higher signal propagation time, which often renders them not suitable for delay intolerant traffic. This paper surveys the current state-of-the-art of satellite and terrestrial network convergence. We mainly focus on scenarios in which satellite networks complement existing terrestrial infrastructures, i.e., parallel satellite and terrestrial links exist, in order to provide high bandwidth connections while ideally achieving a similar end user quality-of-experience as in high bandwidth terrestrial networks. Thus, we identify the technical challenges associated with the convergence of satellite and terrestrial networks and analyze the related work. Based on this, we identify four key functional building blocks, which are essential to distribute traffic optimally between the terrestrial and the satellite networks. These are the traffic requirement identification function, the link characteristics identification function, as well as the traffic engineering function and the execution function. Afterwards, we survey current network architectures with respect to these key functional building blocks and perform a gap analysis, which shows that all analyzed network architectures require adaptations to effectively support converged satellite and terrestrial networks. Hence, we conclude by formulating several open research questions with respect to satellite and terrestrial network convergence.This work was supported by the BATS Research Project through the European Union Seventh Framework Programme under Contract 317533

    Extending Comprehensive Maritime Awareness to Disconnected Vessels and Users

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    After the attacks of 9/11, increased security became a national priority that resulted in a focus on National Maritime Security. Maritime Domain Awareness (MDA) is an initiative developed by the Coast Guard, in partnership with the U.S. Navy and other agencies to increase awareness in the maritime domain in support of maritime security [Morgan and Wimmer, 2005]. The purpose of MDA is to generate actionable intelligence obtained via the collection, fusion and dissemination of information from U.S. joint forces, U.S. government agencies, international coalition partners and commercial entities. This actionable intelligence is the cornerstone of successful counterterrorist and maritime law enforcement operations and is critical to Maritime Security [Morgan and Wimmer, 2005]. The U.S. Navy, as a partner in the development and creation of MDA, has tasked its subordinate commands to identify and define capabilities to support this program. One effort sponsored is the Comprehensive Maritime Awareness (CMA) Joint Capabilities Technology Demonstration (JCTD) [CMA Architecture Team, 2007]. This project supports the CMA JCTD efforts by proposing a deployable system to enable a disconnected vessel to connect to the CMA network. A disconnected user can be seen as a merchant ship, hospital ship or any vessel that is not currently connected to the CMA network. This project's proposed deployable system, as a subset to the CMA network, facilitates information sharing in support of humanitarian efforts worldwide.http://archive.org/details/extendingcompreh109456932N

    Quality of Service Management and Interoperability

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