Spacelab system analysis: A study of communications systems for advanced launch systems

An analysis of the required performance of internal avionics data bases for future launch vehicles is presented. Suitable local area networks that can service these requirements are determined

Spacelab system analysis: A study of the Marshall Avionics System Testbed (MAST)

An analysis of the Marshall Avionics Systems Testbed (MAST) communications requirements is presented. The average offered load for typical nodes is estimated. Suitable local area networks are determined

Spacelab system analysis: The modified free access protocol: An access protocol for communication systems with periodic and Poisson traffic

The protocol definition and terminal hardware for the modified free access protocol, a communications protocol similar to Ethernet, are developed. A MFA protocol simulator and a CSMA/CD math model are also developed. The protocol is tailored to communication systems where the total traffic may be divided into scheduled traffic and Poisson traffic. The scheduled traffic should occur on a periodic basis but may occur after a given event such as a request for data from a large number of stations. The Poisson traffic will include alarms and other random traffic. The purpose of the protocol is to guarantee that scheduled packets will be delivered without collision. This is required in many control and data collection systems. The protocol uses standard Ethernet hardware and software requiring minimum modifications to an existing system. The modification to the protocol only affects the Ethernet transmission privileges and does not effect the Ethernet receiver

Proceedings of the NSSDC Conference on Mass Storage Systems and Technologies for Space and Earth Science Applications

The proceedings of the National Space Science Data Center Conference on Mass Storage Systems and Technologies for Space and Earth Science Applications held July 23 through 25, 1991 at the NASA/Goddard Space Flight Center are presented. The program includes a keynote address, invited technical papers, and selected technical presentations to provide a broad forum for the discussion of a number of important issues in the field of mass storage systems. Topics include magnetic disk and tape technologies, optical disk and tape, software storage and file management systems, and experiences with the use of a large, distributed storage system. The technical presentations describe integrated mass storage systems that are expected to be available commercially. Also included is a series of presentations from Federal Government organizations and research institutions covering their mass storage requirements for the 1990's

Investigation of the consumer electronics bus

The objectives of this dissertation are to investigate the performance of the Consumer Electronics Bus (CEBus) and to develop a theoretical formulation of the Carrier Sense Multiple Access with Contention Detection and Contention Resolution (CSMA/CDCR) with three priority classes protocol utilized by the CEBus A new priority channel assigned multiple access with embedded priority resolution (PAMA/PR) theoretical model is formulated. It incorporates the main features of the CEBus with three priority classes. The analytical results for throughput and delay obtained by this formulation were compared to simulation experiments. A close agreement has been found thus validated both theory and simulation models Moreover, the performance of the CEBus implemented with two physical media, the power line (PL) and twisted pair (TP) communication lines, was investigated by measuring message and channel throughputs and mean packet and message delays. The router was modeled as a node which can handle three priority levels simultaneously. Satisfactory performance was obtained. Finally, a gateway joining the CEBus to ISDN was designed and its perfor-mance was evaluated. This gateway provides access to ISDN-based services to the CEBus. The ISDN and CEBus system network architecture, gateway wiring, and data and signaling interface between the CEBus and ISDN were designed, analyzed, and discussed. Again, satisfactory performance was found

Performance and policy dimensions in internet routing

The Internet Routing Project, referred to in this report as the 'Highball Project', has been investigating architectures suitable for networks spanning large geographic areas and capable of very high data rates. The Highball network architecture is based on a high speed crossbar switch and an adaptive, distributed, TDMA scheduling algorithm. The scheduling algorithm controls the instantaneous configuration and swell time of the switch, one of which is attached to each node. In order to send a single burst or a multi-burst packet, a reservation request is sent to all nodes. The scheduling algorithm then configures the switches immediately prior to the arrival of each burst, so it can be relayed immediately without requiring local storage. Reservations and housekeeping information are sent using a special broadcast-spanning-tree schedule. Progress to date in the Highball Project includes the design and testing of a suite of scheduling algorithms, construction of software reservation/scheduling simulators, and construction of a strawman hardware and software implementation. A prototype switch controller and timestamp generator have been completed and are in test. Detailed documentation on the algorithms, protocols and experiments conducted are given in various reports and papers published. Abstracts of this literature are included in the bibliography at the end of this report, which serves as an extended executive summary

Ethernet Performance: Design and Implementation Study

General concepts concerning local area network designs, functions and topologies will be presented. Ethernet as a multipoint bus topology local area network will be presented in detail. The Carrier Sense Multiple Access/Collision Detect (CSMA/CD) method of fairly regulating access to the shared network bus is studied. The Ethernet Network in relation to the Open Systems Interconnect (OSI) is reviewed, but only the layers pertaining to Ethernet are discussed throughout the majority of the paper. The specifications as described by Xerox, Digital and Intel are presented to help the designer understand the network\u27s physical limitations. Analytical models are used to predict performance and actual measured performance studies will be used to make performance assumptions. The performance is studied under varying load conditions. The data gathered concerns both limits imposed on the number of users by the finite bandwidth of the channel and efficient utilization of that channel. In conclusion, design specifications and performance data will be used together to formulate a design methodology for building the most efficient Ethernet network

The patterns of interorganizational networks in the development of data communication technologies

Title from cover. "February, 1998."Includes bibliographical references (p. 69-75).Pek H. Soh, Edward B. Roberts

SEPEC conference proceedings: Hypermedia and Information Reconstruction. Aerospace applications and research directions

Papers presented at the conference on hypermedia and information reconstruction are compiled. The following subject areas are covered: real-world hypermedia projects, aerospace applications, and future directions in hypermedia research and development

Data systems concepts for space systems, phase 1

Deviations from the traditional spacecraft data systems were studied. A data system architecture was developed from the top down