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Mobile Satellite (mobile + satellite)

Distribution by Scientific Domains
Engineering85%

Terms modified by Mobile Satellite

  • mobile satellite channel
    		•

    Selected Abstracts

    An adaptive path routing scheme for satellite IP networks

    INTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 1 2003
    Jing Chen
    Abstract Mobile satellites can be considered as the promising solution to the global IP network. In order to provide quality of service (QoS) in future networks, mobile satellite can be integrated with the asynchronous transfer mode (ATM) to switch IP datagrams in the space. For such a network, new and sophisticated routing and handoff algorithms are essential. In this paper, a new scheme called adaptive path routing scheme (APRS) is proposed. It is shown that the APRS can provide superior performance for routing and handoff in mobile satellite networks compared with conventional schemes. Copyright © 2003 John Wiley & Sons, Ltd. [source]

    An enhanced Markov chain based model for the narrowband LMS channel in built-up areas

    INTERNATIONAL JOURNAL OF SATELLITE COMMUNICATIONS AND NETWORKING, Issue 2 2005
    F. Perez-Fontán
    Abstract In this paper, a technique to derive the transition probabilities for a Markov chain model for the land mobile satellite (LMS) channel in built-up areas is presented. This technique contributes to improving empirically derived parameters in that it can account for elevation and street orientation effects as well as building density. Physical-statistical or ,virtual city' techniques are used to relate observed edification statistics to signal attenuation statistics. This methodology can also be applied to generating correlated time-series for simultaneous links to a constellation of satellites from the same mobile terminal. The proposed approach also allows the generation of enhanced time-series which take into account diffuse multipath and diffraction effects. Copyright © 2005 John Wiley & Sons, Ltd. [source]

    Approximate urban area call drop-out probability estimation in mobile multi-satellite systems

    INTERNATIONAL JOURNAL OF SATELLITE COMMUNICATIONS AND NETWORKING, Issue 2 2003
    F. Perez-Fontan
    Land mobile satellite (LMS) systems require constellations of multiple satellites to compensate for the large blockage probabilities suffered in urban areas. An approximate methodology based on the street masking function (MKF) or mask concept is presented for the evaluation of system availability. MKFs are graphical representations of the angles (azimuths and elevations) for which a satellite is visible from the terminal's location in the street. MKFs can also be used in the evaluation of second order statistics such as durations of fades or connections. In this paper, the applicability of the mask concept is demonstrated by performing a study of the probability of successful call completion in a LEO-based satellite telephony service. Copyright © 2003 John Wiley & Sons, Ltd. [source]

    Physical,statistical methods for determining state transition probabilities in mobile-satellite channel models

    INTERNATIONAL JOURNAL OF SATELLITE COMMUNICATIONS AND NETWORKING, Issue 3 2001
    S. R. Saunders
    Abstract Signal propagation in land mobile satellite (LMS) communication systems has for the last decade become an essential consideration, especially when high-rate data services are involved. As far as urban or suburban built-up areas are concerned, the extent of the influence is mainly restricted to the roadside obstacles, since the satellite is positioned at relatively high elevation angles in most practical situations. Probably, the most common model currently used for representing the LMS channel is the Lutz model, which uses two states to represent line-of-sight and non-line-of-sight conditions. Transitions between these states are described by transition probabilities which are a function of the environment and the satellite elevation angles. Similarly, an extension to the model allows a four-state description to be used for the states associated with a pair of satellites used in a dual-diversity configuration. Calculation of the transition probabilities then requires knowledge of the correlation between the two channels, which in turn depends on the spatial characteristics of the local environment around the mobile. In both cases, the transition probabilities have been derived basically from measurements in the past. In the new approaches described in this paper, physical,statistical principles are applied to construct analytical formulas for the probabilities of shadowing and the correlation between states. These expressions apply particularly to systems operated in built-up environments, and have been checked against numerical experiments and against direct measurements. In both cases excellent agreement is obtained. Copyright © 2001 John Wiley & Sons, Ltd. [source]

    Propagation considerations and fading countermeasures for mobile multimedia services

    INTERNATIONAL JOURNAL OF SATELLITE COMMUNICATIONS AND NETWORKING, Issue 3 2001
    Axel Jahn
    Abstract This paper presents a summary of land mobile satellite (LMS) channel characteristics derived from several measurement campaigns. Narrowband and wideband measurements allow a broad interpretation of the LMS channels. Channel models and its parameters have been derived from the measured data as well. Furthermore, the impact of the LMS channel on the communication service is investigated and possible countermeasures are discussed. Link margins, power control schemes and satellite diversity can compensate the fading on the transmission links. The benefit of adaptive receivers and the dependence on the signal bandwidth are investigated, too. Copyright © 2001 John Wiley & Sons, Ltd. [source]

    MPE-IFEC: An enhanced burst error protection for DVB-SH systems

    BELL LABS TECHNICAL JOURNAL, Issue 1 2009
    Bessem Sayadi
    Digital video broadcasting-satellite services to handhelds (DVB-SH) is a new hybrid satellite/terrestrial system for the broadcasting of multimedia services to mobile receivers. To improve the link budget, DVB-SH uses a long interleaver to cope with land mobile satellite (LMS) channel impairments. Multi-protocol encapsulation,inter-burst forward error correction (MPE-IFEC) is an attractive alternative to the long physical interleaving option of the standard and is suited for terminal receivers with limited de-interleaving memory. In this paper, we present a tutorial overview of this powerful error-correcting technique and report new simulation results that show MPE-IFEC improves the quality of broadcast mobile television (TV) reception. © 2009 Alcatel-Lucent. [source]