1,108 research outputs found

    Applications of satellite technology to broadband ISDN networks

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    Two satellite architectures for delivering broadband integrated services digital network (B-ISDN) service are evaluated. The first is assumed integral to an existing terrestrial network, and provides complementary services such as interconnects to remote nodes as well as high-rate multicast and broadcast service. The interconnects are at a 155 Mbs rate and are shown as being met with a nonregenerative multibeam satellite having 10-1.5 degree spots. The second satellite architecture focuses on providing private B-ISDN networks as well as acting as a gateway to the public network. This is conceived as being provided by a regenerative multibeam satellite with on-board ATM (asynchronous transfer mode) processing payload. With up to 800 Mbs offered, higher satellite EIRP is required. This is accomplished with 12-0.4 degree hopping beams, covering a total of 110 dwell positions. It is estimated the space segment capital cost for architecture one would be about 190Mwhereasthesecondarchitecturewouldbeabout190M whereas the second architecture would be about 250M. The net user cost is given for a variety of scenarios, but the cost for 155 Mbs services is shown to be about $15-22/minute for 25 percent system utilization

    Resource management for multimedia traffic over ATM broadband satellite networks

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    Flexible QoS Support in DVB-RCS2

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    Study of the CAC mechanisms for telecommunications systems with adaptive links according to propagation conditions

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    This paper presents the framework and the activities of a PhD research work in progress supported by Alcatel Alenia Space in collaboration with TeSA and SUPAERO. It deals with Connection Admission Control (CAC) for Telecommunications Systems with adaptive links according to propagation conditions. Indeed, in high frequency bands communications, deep fadings may occur because of atmospheric propagation losses. The mitigation techniques used to counteract fades impacts the system capacity, therefore the CAC mechanism. The CAC which only uses current capacity information may lead to intolerable dropping of admitted connection, and thus breaches the QoS guarantees made upon connection acceptance. New CAC mechanisms shall be studied to take into account the capacity variation and the mitigation techniques (IFMT) developed to compensate the attenuation in Ka and above frequency range

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

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    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

    Satellite diversity system emulator

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    Current satellite telecommunication systems are facing growing demand, in particular for broadband markets. In order to reach higher data rate and minimize the cost per Mbps, upcoming VHTS systems are targeting Terabit capacity. One of the most promising solution is to dedicate the whole Ka band to the user links to maximize the user link capacity whereas the feeder links operate in Q/V bands. However, the use of these higher frequencies (in the Q/V bands) raises new challenges, because of the increased sensitivity of these bands to meteorological events that may affect gateways link budget, making them unable to handle any traffic during a rain event. A simple solution to this shortcoming for ensuring constant service to users is to add additional gateways to the system and perform a handover to a redundancy gateway when a nominal gateway faces too strong fading 3,4. For example, a pan-european system with a dozen of operational gateways and a few redundancy gateways would be economically viable: the additional cost of the redundancy gateway is not offset by the benefits of increased system availability. Different design choices to realize diversity are possible 5: this work studies in particular geographical diversity, or (n+p) diversity. This (n+p) diversity scheme provides extremely high availability with very few redundant gateways. However, the impacts on services has still to be evaluated. This paper presents a diversity emulation test-bed developed to experiment different types of gateway handover scenarios to measure their impact on user’s experience. This emulator has been developed by IRT Saint-ExupĂ©ry in the framework of the ALBS project (Advanced Link for Broadband Satellite). The emulator is able to simulate both ground network and satellite links, up to the user’s terminals. It is designed to be representative of the network transit and switching losses and delays, as well as the satellite onboard switch behavior. The emulator is used to investigate the influence of the effects that switching mechanisms can have on the ongoing communications. It will also allow to investigate design optimization and provide recommendations to handle these ongoing communication during the gateway handover
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