2,357 research outputs found

    Applications of satellite technology to broadband ISDN networks

    Get PDF
    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

    Energy-efficient wireless communication

    Get PDF
    In this chapter we present an energy-efficient highly adaptive network interface architecture and a novel data link layer protocol for wireless networks that provides Quality of Service (QoS) support for diverse traffic types. Due to the dynamic nature of wireless networks, adaptations in bandwidth scheduling and error control are necessary to achieve energy efficiency and an acceptable quality of service. In our approach we apply adaptability through all layers of the protocol stack, and provide feedback to the applications. In this way the applications can adapt the data streams, and the network protocols can adapt the communication parameters

    Quality of Service over Specific Link Layers: state of the art report

    Get PDF
    The Integrated Services concept is proposed as an enhancement to the current Internet architecture, to provide a better Quality of Service (QoS) than that provided by the traditional Best-Effort service. The features of the Integrated Services are explained in this report. To support Integrated Services, certain requirements are posed on the underlying link layer. These requirements are studied by the Integrated Services over Specific Link Layers (ISSLL) IETF working group. The status of this ongoing research is reported in this document. To be more specific, the solutions to provide Integrated Services over ATM, IEEE 802 LAN technologies and low-bitrate links are evaluated in detail. The ISSLL working group has not yet studied the requirements, that are posed on the underlying link layer, when this link layer is wireless. Therefore, this state of the art report is extended with an identification of the requirements that are posed on the underlying wireless link, to provide differentiated Quality of Service

    The Octopus switch

    Get PDF
    This chapter1 discusses the interconnection architecture of the Mobile Digital Companion. The approach to build a low-power handheld multimedia computer presented here is to have autonomous, reconfigurable modules such as network, video and audio devices, interconnected by a switch rather than by a bus, and to offload as much as work as possible from the CPU to programmable modules placed in the data streams. Thus, communication between components is not broadcast over a bus but delivered exactly where it is needed, work is carried out where the data passes through, bypassing the memory. The amount of buffering is minimised, and if it is required at all, it is placed right on the data path, where it is needed. A reconfigurable internal communication network switch called Octopus exploits locality of reference and eliminates wasteful data copies. The switch is implemented as a simplified ATM switch and provides Quality of Service guarantees and enough bandwidth for multimedia applications. We have built a testbed of the architecture, of which we will present performance and energy consumption characteristics

    Design techniques for low-power systems

    Get PDF
    Portable products are being used increasingly. Because these systems are battery powered, reducing power consumption is vital. In this report we give the properties of low-power design and techniques to exploit them on the architecture of the system. We focus on: minimizing capacitance, avoiding unnecessary and wasteful activity, and reducing voltage and frequency. We review energy reduction techniques in the architecture and design of a hand-held computer and the wireless communication system including error control, system decomposition, communication and MAC protocols, and low-power short range networks

    Information Switching Processor (ISP) contention analysis and control

    Get PDF
    Future satellite communications, as a viable means of communications and an alternative to terrestrial networks, demand flexibility and low end-user cost. On-board switching/processing satellites potentially provide these features, allowing flexible interconnection among multiple spot beams, direct to the user communications services using very small aperture terminals (VSAT's), independent uplink and downlink access/transmission system designs optimized to user's traffic requirements, efficient TDM downlink transmission, and better link performance. A flexible switching system on the satellite in conjunction with low-cost user terminals will likely benefit future satellite network users

    A robust coding scheme for packet video

    Get PDF
    A layered packet video coding algorithm based on a progressive transmission scheme is presented. The algorithm provides good compression and can handle significant packet loss with graceful degradation in the reconstruction sequence. Simulation results for various conditions are presented

    A robust coding scheme for packet video

    Get PDF
    We present a layered packet video coding algorithm based on a progressive transmission scheme. The algorithm provides good compression and can handle significant packet loss with graceful degradation in the reconstruction sequence. Simulation results for various conditions are presented

    Traffic Control in a Synchronous Transfer Mode Networks

    Get PDF
    In the 90s, there is an increasing demand for new telecommunication services such as video conferencing, videophone, broadcast television, image transfer and bulk file transfe r etc. At the same time, transmission systems at bit rates of 2.5 Gb/s are now being installed, and the expected next generation of 10 Gb/s systems is emerging from the research laboratories. Coupled with that the development and deployment of new technologies systems such as fiber optics and intelligent high-speed switches have made it possible to provide these services in future high-speed integrated services networks like Asynchronous Transfer Mode (ATM). However, because of their new characteristics, these new services pose great challenges not previously encountered in traditional circuitswitche d or packet switched networks. For example, feature s such as large propagation delay as compared to transmission delay, diverse application demands, constraints on call processing capacity, and Quality-Of-Service (QOS) support for different applications all present new challenges arising from the new technology and new applications. Thus, much research is needed not just to improve existing technologies, but to seek a fundamentally different approach toward network architectures and protocols. In particular, new bandwidth allocation and call admission control algorithms need to be studied to meet these new challenges. A VP bandwidth allocation problem is studied for services which requires guaranteed connection for a fixed duration of time leading to extensive use of facilities like reservations of transmission capacity in advance. In such a case, the network may offer discounts for users reserving capacities in advance due to the advantage of working with predetermined traffic loads. Similarly, charges may differ for customers wanting to book capacity for a specified tie interval. Based on this scenario, various charge classes and booking policies are introduced. An effective bandwidth allocation scheme is proposed at the VP level with multiple nested charge classes where these various classes are allocated bandwidth optimally through some booking policies'. The scheme is also shown to be effective in maximizing network revenue. The best tradeoff between revenue gained through greater demand for discount bandwidth units against revenue lost when full-charge bookings request must be turned away because of prior bookings of discount bandwidth units is also sought for

    Switching techniques in data-acquisition systems for future experiments

    Get PDF
    An overview of the current state of development of parallel event-building techniques is given, with emphasis of future applications in the high-rate experiments proposed at the Large Hadron Collider (LHC). The paper describes the ain architectural options in parallel event builders, the proposed event-building architectures for LHC experiments, and the use of standard net- working protocols for event building and their limitations. The main issues around the potential use of circuit switching, message switching and packet switching are examined. Results from various laboratory demonstrator systems are presented
    • …
    corecore