Multimedia Networks: Fundamentals and Future Directions

Multimedia has become an integral part of computing and communications environment, and networks are carrying ever-increasing volume of multimedia information. The main characteristics of multimedia information are high-volume and bursty traffic, with low tolerance to delay and delay variance. The legacy networks (designed in 70s and 80s) are not able to meet these requirements. Enhancements to the older networking technologies have been developed to convert these into multimedia networks. Enhancements to LANs include Switched Ethernet, Isochronous Ethernet, Fast Ethernet, 100VGAnyLAN, FDDI-II, and Synchronous FDDI. WAN options for multimedia networking include digital leased lines and ISDN. The Internet has revolutionized business and personal communications, but falls short of being a genuine multimedia network. To make the Internet capable of carrying multimedia traffic, new protocols such as MBone, ST-II, RTP, and RSVP have been developed. Internet2 is a new initiative that is aimed at overcoming the problems of throughput, delay and jitter encountered on the original Internet. One technology that was developed with multimedia networking as one of its main applications, is the Asynchronous Transfer Mode (ATM) technology. Upcoming Gigabit Ethernet technology will provide a path for upgrading current Ethernet networks into multimedia networks

Deep Space Network information system architecture study

The purpose of this article is to describe an architecture for the Deep Space Network (DSN) information system in the years 2000-2010 and to provide guidelines for its evolution during the 1990s. The study scope is defined to be from the front-end areas at the antennas to the end users (spacecraft teams, principal investigators, archival storage systems, and non-NASA partners). The architectural vision provides guidance for major DSN implementation efforts during the next decade. A strong motivation for the study is an expected dramatic improvement in information-systems technologies, such as the following: computer processing, automation technology (including knowledge-based systems), networking and data transport, software and hardware engineering, and human-interface technology. The proposed Ground Information System has the following major features: unified architecture from the front-end area to the end user; open-systems standards to achieve interoperability; DSN production of level 0 data; delivery of level 0 data from the Deep Space Communications Complex, if desired; dedicated telemetry processors for each receiver; security against unauthorized access and errors; and highly automated monitor and control

ISDN at NASA Lewis Research Center

An expository investigation of the potential impact of the Integrated Services Digital Network (ISDN) at NASA Lewis Research Center is described. To properly frame the subject, the paper contains a detailed survey of the components of Narrowband ISDN. The principles and objectives are presented as decreed by the Consultative Committee for International Telephone and Telegraph (CCITT). The various channel types are delineated and their associated service combinations are described. The subscriber-access network functions are explained pictorially via the ISDN reference configuration. A section on switching techniques is presented to enable the reader to understand the emergence of the concept of fast packet switching. This new technology is designed to operate over the high bandwidth, low error rate transmission media that characterizes the LeRC environment. A brief introduction to the next generation of networks is covered with sections on Broadband ISDM (B-ISDN), Asynchronous Transfer Mode (ATM), and Synchronous Optical Networks (SONET). Applications at LeRC are presented, first in terms of targets of opportunity, then in light of compatibility constraints. In-place pilot projects and testing are described that demonstrate actual usage at LeRC

Design and analysis of a medium access and control strategy for extending the ISDN services to LAN users

A significant portion of the contemporary research efforts in the area of data communications and computer networking is devoted to Local Area Networks (LANs) and Integrated Services Digital Networks (ISDNs). Both, ISDN and LAN, are being developed to satisfy the key requirements of their specific applications. This application specific development has created a semantic gap between ISDN and LANs. Consequently, an extensive mapping is required to interface an ISDN with a LAN. Obviously, such mapping may limit the overall performance of a LAN;In this dissertation, a Medium Access and Control Strategy (MACS) is proposed that does not require a complex ISDN/LAN interface and extends the ISDN services to a LAN user without degrading the performance of the LAN. The proposed MACS is distributed in nature, supports a prioritized realtime traffic (using dynamically controlled target token rotation time), provides packet switching and circuit switching facilities, and can be implemented on a single ring topology;The analysis of the strategy indicates that a channel capacity of 64 Kbps is sufficient to carry the control and signalling information for 100 stations. The simulation results show that the network performance is drastically degraded at lower values of the target token rotation time. The proposed strategy solves this problem by dynamically adjusting the target token rotation time

An Integrated Network Architecture for a High Speed Distributed Multimedia System.

Computer communication demands for higher bandwidth and smaller delays are increasing rapidly as the march into the twenty-first century gains momentum. These demands are generated by visualization applications which model complex real time phenomena in visual form, electronic document imaging and manipulation, concurrent engineering, on-line databases and multimedia applications which integrate audio, video and data. The convergence of the computer and video worlds is leading to the emergence of a distributed multimedia environment. This research investigates an integrated approach in the design of a high speed computer-video local area network for a distributed multimedia environment. The initial step in providing multimedia services over computer networks is to ensure bandwidth availability for these services. The bandwidth needs based on traffic generated in a distributed multimedia environment is computationally characterized by a model. This model is applied to the real-time problem of designing a backbone for a distributed multimedia environment at the NASA Classroom of the Future Program. The network incorporates legacy LANs and the latest high speed switching technologies. Performance studies have been conducted with different network topologies for various multimedia application scenarios to establish benchmarks for the operation of the network. In these performance studies it has been observed that network topologies play an important role in ensuring that sufficient bandwidth is available for multimedia traffic. After the implementation of the network and the performance studies, it was found that for true quality of service guarantees, some modifications will have to be made in the multimedia operating systems used in client workstations. These modifications would gather knowledge of the channel between source and destination and reserve resources for multimedia communication based on specified requirements. A scheme for reserving resources in a network consisting legacy LAN and ATM is presented to guarantee quality of service for multimedia applications

Application of Asynchronous Transfer Mode (Atm) technology to Picture Archiving and Communication Systems (Pacs): A survey

Broadband Integrated Services Digital Network (R-ISDN) provides a range of narrowband and broad-band services for voice, video, and multimedia. Asynchronous Transfer Mode (ATM) has been selected by the standards bodies as the transfer mode for implementing B-ISDN; The ability to digitize images has lead to the prospect of reducing the physical space requirements, material costs, and manual labor of traditional film handling tasks in hospitals. The system which handles the acquisition, storage, and transmission of medical images is called a Picture Archiving and Communication System (PACS). The transmission system will directly impact the speed of image transfer. Today the most common transmission means used by acquisition and display station products is Ethernet. However, when considering network media, it is important to consider what the long term needs will be. Although ATM is a new standard, it is showing signs of becoming the next logical step to meet the needs of high speed networks; This thesis is a survey on ATM, and PACS. All the concepts involved in developing a PACS are presented in an orderly manner. It presents the recent developments in ATM, its applicability to PACS and the issues to be resolved for realising an ATM-based complete PACS. This work will be useful in providing the latest information, for any future research on ATM-based networks, and PACS

Future benefits and applications of intelligent on-board processing to VSAT services

The trends and roles of VSAT services in the year 2010 time frame are examined based on an overall network and service model for that period. An estimate of the VSAT traffic is then made and the service and general network requirements are identified. In order to accommodate these traffic needs, four satellite VSAT architectures based on the use of fixed or scanning multibeam antennas in conjunction with IF switching or onboard regeneration and baseband processing are suggested. The performance of each of these architectures is assessed and the key enabling technologies are identified

Space station Simulation Computer System (SCS) study for NASA/MSFC. Volume 3: Refined conceptual design report

The results of the refined conceptual design phase (task 5) of the Simulation Computer System (SCS) study are reported. The SCS is the computational portion of the Payload Training Complex (PTC) providing simulation based training on payload operations of the Space Station Freedom (SSF). In task 4 of the SCS study, the range of architectures suitable for the SCS was explored. Identified system architectures, along with their relative advantages and disadvantages for SCS, were presented in the Conceptual Design Report. Six integrated designs-combining the most promising features from the architectural formulations-were additionally identified in the report. The six integrated designs were evaluated further to distinguish the more viable designs to be refined as conceptual designs. The three designs that were selected represent distinct approaches to achieving a capable and cost effective SCS configuration for the PTC. Here, the results of task 4 (input to this task) are briefly reviewed. Then, prior to describing individual conceptual designs, the PTC facility configuration and the SSF systems architecture that must be supported by the SCS are reviewed. Next, basic features of SCS implementation that have been incorporated into all selected SCS designs are considered. The details of the individual SCS designs are then presented before making a final comparison of the three designs

An Investigation of alternative communication methods to face to face interaction between design and client

As technology becomes increasingly more sophisticated, means and demand for digital communication are increasing. The geographical expansion of the business world has made communication alternatives critical to working together more effectively. Face to face meetings may not be possible or the most cost and time efficient approach. Also, there is a move towards working at home, telecommuting, by using electronic communication for interaction (Fitzgerald 1993). Thus, electronic correspondence is becoming essential and we are witnessing a move towards higher performance and potential for communication alternatives. Knowing the options and their appropriateness is a competitive advantage. In a information society dominated by computers and communications, value is increased by knowledge, as well as by the speed of movement of that knowledge. (Fitzgerald 1994). Graphic designers rely on strong communication with their clients. Clients\u27 needs must be expressed to the designer and designer\u27s solutions must be communicated for approval. This process is repeated at several stages: initial, revision, and final. Traditionally, when face to face meetings were not feasible, comprehensives were mailed to the client. With the current move towards electronic communication, mail manual transportation are slower and possibly more expensive than electronic correspondence. With technology today, electronic correspondence may also include interactivity, voice, and video. The purpose of this thesis is to investigate alternative methods to face to face interaction between designer and client throughout the design approval process. The goal being to determine the appropriateness of each transmission application for information interchange of different kind of images and at different stages of the approval process. Appropriateness was to be determined by equipment, economic and time factors, interoperability, security, and aesthetic and communication quality. Facsimile technology, Adobe Acrobat\u27s portable document formal files, the Internet, and videoconferencing were the vehicles analyzed as an electronic correspondence alternatives to face to face interaction. The vehicles were tested in two parts, through survey and actual transactions with graphic designers. Participants were provided questionnaires to evaluate and compare the visual and non visual aspects of each vehicle. This thesis did not test specific software or hardware, but rather the validity of the technique for interaction and transmission of data between designer and client throughout the design approval process. The test was in two parts. The first part was a survey sampling of 1 00 design sites, design firms and advertising agencies, to derive quantitative information on each transmission vehicle Based on the assessment of the appropriateness of each vehicle, determined by survey response in conjunction with background research, Facsimile technology, Adobe Acrobat, and videoconferencing were deemed appropriate for further testing. The Internet was deemed inappropriate. Three design sites were involved in comparing facsimile technology and PDF files to dye sublimation hardcopy prints. A video-conference was donated, conducted, and videotaped. Participants were asked to evaluate and compare visual and non-visual aspects of the transmitted comprehensives. The conclusion of this thesis project is that the technology is here to use for electronic alternatives to face to face interaction between clients. Some adjustments have to be made, though, before these technologies can be embraced completely. Electronic alternatives are not qualified for final approval because of lack of precision in color, lack of demonstrating production or finishing operations, and the quality of typography on monitors are extremely low causing the aesthetic quality to be extremely diminished. Second, the designers selected hardcopy as the best option for communicating the tested designs. This indicates the community is not ready to embrace electronic alternatives. This may be due to a lacking of advantage of the electronic option to deem them necessary and/or lack of comfortability with the electronic alternatives. Either reason, electronic alternatives to face to face interaction between client and designer is not, currenly, being fully accepted. As for the vehicles themselves, Adobe Acrobat was found to be a very appropriate product to use between designer and client to communicate design comprehensives for initial and revision stages. Facsimile transmissions are appropriate for initial comprehensives or for revisions of comprehensives already seen at higher quality by the client. The Internet is presently not appropriate for private one-to-one file transfer between client and designer. Its strengths do not outweigh its risks. Videoconferencing is electronic correspondence, not file transfer. It can be used in combination with mail carrier service and file transfer or alone. If the client has been sent appropriate final proofs and the conference is used for verbal and visual communication, it is appropriate for all stages. If the final proof has not been sent, it is very appropriate for initial and revision stages. In comparison to mail carriers, all electronic options transmission times were significantly faster. All transmissions were under a hour. Additionally, all alternatives except videoconferencing, were less expensive