Institute for Systems Research Technical Reports

Permanent URI for this collectionhttp://hdl.handle.net/1903/4376

This archive contains a collection of reports generated by the faculty and students of the Institute for Systems Research (ISR), a permanent, interdisciplinary research unit in the A. James Clark School of Engineering at the University of Maryland. ISR-based projects are conducted through partnerships with industry and government, bringing together faculty and students from multiple academic departments and colleges across the university.

Browse

Author: search.filters.author.Atallah, George C.

Search Results

Now showing 1 - 5 of 5
  • Thumbnail Image
    Item
    Collaborative Simulation for Hybrid Networks
    (1996) Gupta, Sandeep; Baras, John S.; Atallah, George C.; ISR; CSHCN
    An experiment for using more than one simulation of sub-networks collaborating as a single large simulation is suggested, based on work with a similar situation. The background and relevant details of the initial solution are described to provide an outline for the solution. Work on this method will help development of simulations for hybrid networks, where newer pieces may be added to the simulation without having to build a large, monolithic and a site-centric development effort
  • Thumbnail Image
    Item
    A Summary of Satellite Orbit Related Calculations
    (1995) Murad, A.H.; Jang, Kap D.; Atallah, George C.; Karne, Ramesh K.; Baras, John S.; ISR; CSHCN
    The configuration of satellite network systems is based on the quantities and properties related to the satellite orbit. It is extremely important to carefully define parameters and equations describing the orbit  path correctly to make the whole configuration correct. Three different coordinate systems are in use to define satellite orbit: the Latitude-Longitude-Altitude coordinate system, the Right Ascension-Declination coordinate system and the Azimuth-Elevation coordinate system. These coordinate systems are equivalent with respect to the position of the satellite of interest and can easily be converted one to another. One of these coordinate systems would be used depending on the nature of the problem to be solved. Based upon these coordinate systems, the position of a satellite, the visibility of a satellite and antenna direction from a ground station, and a footprint radius of a satellite, etc. can be calculated.

  • Thumbnail Image
    Item
    Object Oriented Hybrid Network Simulation
    (1994) Baras, John S.; Atallah, George C.; Karne, Ramesh K.; Murad, A.; Jang, Kap D.; ISR; CSHCN
    As the complexity and diversity of networks have grown, simulation has proved an important tool in their design, analysis, testing and performance estimation of networks. Hybrid networks involve a variety of network elements - both mobile (e.g., satellites, mobile radio) and fixed nodes (e.g., switches, hubs, network gateways) linked via varied broadcast, multicast and point-to-point communication channels. Because of their complex nature, design and evaluation of hybrid networks is a particularly complicated task. Major requirements of a hybrid network simulation tool are (i) Flexibility and Adaptability - to accommodate all kinds of hybrid networks and protocols, (ii) Advanced Network Visualization Techniques - to clearly visualize complex communication network systems, (iii) Data Management - to organize and analyze the vast quantities of data generated in a typical simulation run, and (iv) Distributed Implementation - to fully utilize available computing resources to speed up simulation. This paper describes the design and functional description of an Object-Oriented Hybrid Network Simulation tool. Its object oriented design and implementation (in C++) allows flexibility through incorporation of new, user specified network elements, protocols and functional blocks. Advanced visualization techniques are combined with the graphical user interface to allow better visualization of complex network structures. A sophisticated geographical database is also incorporated to aid terrestrial mobile, and satellite network systems. To handle and effectively analyze the vast quantities of data generated, an object-oriented database is incorporated into the simulation. In addition to network simulation, the tool is also designed to serve other needs. An interface is provided to allow the user to run real network applications over the simulated network, allowing network application designers to judge the performance of their applications over various network configurations. Incorporation of a database allows computation of network performance dynamically. A network management tool receiving network performance data both from the actual and the simulated network may use the simulation data to make a long term prediction of the actual network behavior to perform long-term network management.
  • Thumbnail Image
    Item
    Advanced Orbiting Systems Data Generator/Simulator: A Functional Description of the Software (Version 3)
    (1994) Baras, John S.; Atallah, George C.; Fuja, Tom E.; Murad, A.; Jang, Kap D.; ISR; CSHCN
    The Advanced Orbiting System (AOS) Data Generator/Simulator is a software implementation of the transmitter (data generation) section of the CCSDS Recommendation 701.0-B-2 for Advanced Orbiting Systems: Networks and Data Links. An object-oriented approach to the simulation of a complex, high-performance communication protocol, it makes full use of the concepts of data-encapsulation and inheritance to ease implementation. The backbone of the software is a general-purpose packet description and generation module that may be used as part of any packet- based simulation software. The user-interface to the program is in the form of a command-language, designed to ease the process of generation of large, multiple data-streams. The output of the program may be configured for interpretation by a graphical user interface (for visual inspection of the data), or as a bit-stream suitable for further processing. This paper consists of three sections. The first two sections provide a brief, yet comprehensive description of the above CCSDS Recommendation. The various kinds and qualities of user-services, data units involved, and data-paths defined by the protocol are discussed. The different qualities of service (in terms or data reliability) available to the user (and the error-control schemes used to provide them) are also discussed. The last section describes the structure and user-interfaces of the AOS Data Generator/Simulator.
  • Thumbnail Image
    Item
    Next Generation Network Management Technology
    (1994) Atallah, George C.; Ball, Michael O.; Baras, John S.; Goli, Shravan K.; Karne, Ramesh K.; Kelley, Stephen; Kumar, Harsha P.; Plaisant, Catherine; Roussopoulos, Nick; Shneiderman, Ben; Srinivasarao, Mulugu; Stathatos, Kostas; Teittinen, Marko; Whitefield, David; ISR; CSHCN
    Today's telecommunications networks are becoming increasingly large, complex, mission critical and heterogeneous in several dimensions. For example, the underlying physical transmission facilities of a given network may be ﲭixed media (copper, fiber- optic, radio, and satellite); the sub networks may be acquired from different vendors due to economic, performance, or general availability reasons; the information being transmitted over the network may be ﲭultimedia (video, data, voice, and images) and, finally, varying performance criteria may be imposed e.g. data transfer may require high throughput while the others, whose concern is voice communications, may require low call blocking probability. For these reasons, future telecommunications networks are expected to be highly complex in their services and operations. Due to this growing complexity and the disparity among management systems for individual sub networks, efficient network management systems have become critical to the current and future success of telecommunications companies. This paper addresses a research and development effort which focuses on prototyping configuration management, since that is the central process of network management and all other network management functions must be built upon it. Our prototype incorporates ergonomically designed graphical user interfaces tailored to the network configuration management subsystem and to the proposed advanced object-oriented database structure. The resulting design concept follows open standards such as Open Systems Interconnection (OSI) and incorporates object oriented programming methodology to associate data with functions, permit customization, and provide an open architecture environment.
      A revised version of this technical report has been published in
      The 12th Symposium on Space Nuclear Power and Propulsion/Commercialization, pp. 75-82, Albuquerque, NM, January 8-12, 1995.