NASA and the challenge of ISDN: The role of satellites in an ISDN world

To understand what role satellites may play in Integrated Services Digital Network (ISDN), it is necessary to understand the concept of ISDN, including key organizations involved, the current status of key standards recommendations, and domestic and international progress implementation of ISDN. Each of these areas are explained. A summary of the technical performance criteria for ISDN, current standards for satellites in ISDN, key players in the ISDN environment, and what steps can be taken to encourage application of satellites in ISDN are also covered

Introduction of a pseudo-6th order ISDN splitter with bandstop topology

A newly developed ‘integrated services digital network’ (ISDN) splitter with bandstop (BS) topology is presented and compared to an actual ISDN splitter with a traditional lowpass (LP) topology. The LP-to-BS topology change reduced the amount of filter stages: a LP ISDN splitter requires an 8th order elliptic-like filter in order to be compliant to the standard ‘TS 101 952-1-4 V1.1.1’ [1] of the European Telecommunications Standards Institute (ETSI), whereas the BS ISDN splitter only needs a pseudo-6th order elliptic-like filter. The design of the new BS ISDN filter is discussed in the light of the enforced ETSI specifications. Furthermore, both the ISDN splitters are compared in the field of their specific stopband performance and their physical implementation. The area reduction that comes together with the introduction of the new ISDN splitter with BS topology is more than 25%

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

Flexible digital modulation and coding synthesis for satellite communications

An architecture and a hardware prototype of a flexible trellis modem/codec (FTMC) transmitter are presented. The theory of operation is built upon a pragmatic approach to trellis-coded modulation that emphasizes power and spectral efficiency. The system incorporates programmable modulation formats, variations of trellis-coding, digital baseband pulse-shaping, and digital channel precompensation. The modulation formats examined include (uncoded and coded) binary phase shift keying (BPSK), quatenary phase shift keying (QPSK), octal phase shift keying (8PSK), 16-ary quadrature amplitude modulation (16-QAM), and quadrature quadrature phase shift keying (Q squared PSK) at programmable rates up to 20 megabits per second (Mbps). The FTMC is part of the developing test bed to quantify modulation and coding concepts

Radio frequency optimization of a Global System for Mobile (GSM) network

Includes bibliographical references

Service offerings and interfaces for the ACTS network of Earth stations

The Advanced Communications Satellite (ACTS) is capable of two modes of communication. Mode 1 is a mesh network of Earth stations using baseband-switched, time-division multiple-access (BBS-TDMA) and hopping beams. Mode 2 is a mesh network using satellite-switched, time-division multiple-access (SS-TDMA) and fixed (or hopping) beams. The purpose of this paper is to present the functional requirements and the design of the ACTS Mode 1 Earth station terrestrial interface. Included among the requirements are that: (1) the interface support standard telecommunications service offerings (i.e., voice, video and data at rates ranging from 9.6 kbps to 44 Mbps); (2) the interface support the unique design characteristics of the ACTS communications systems (e.g., the real time demand assignment of satellite capacity); and (3) the interface support test hardware capable of validating ACTS communications processes. The resulting interface design makes use of an appropriate combination of T1 or T3 multiplexers and a small central office (maximum capacity 56 subscriber lines per unit)

A B-ISDN-compatible modem/codec

Coded modulation techniques for development of a broadband integrated services digital network (B-ISDN)-compatible modem/codec are investigated. The selected baseband processor system must support transmission of 155.52 Mbit/s of data over an INTELSAT 72-MHz transponder. Performance objectives and fundamental system parameters, including channel symbol rate, code rate, and the modulation scheme are determined. From several candidate codes, a concatenated coding system consisting of a coded octal phase shift keying modulation as the inner code and a high rate Reed-Solomon as the outer code is selected and its bit error rate performance is analyzed by computer simulation. The hardware implementation of the decoder for the selected code is also described

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

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

A Hybrid voice/text electronic mail system: an application of the integrated services digital network

The objective of this thesis is to present a useful application for the Integrated Services Digital Network (ISDN) that is expected to one day replace the analog phone system in use today. ISDN itself and its continuing evolution are detailed. The system developed as a part of this thesis involved the creation of an inexpensive phone terminal that can serve as an ISDN terminal and also as a bridge to a Local Area Network (LAN). The phone terminal provides a hybrid electronic mail system that allows the attachment of speech to text within a message. Messages created with this phone terminal could theoretically be sent locally using the LAN interface and globally using ISDN to other users with either phone terminals or multimedia personal computers. For this project, the two phone terminals created were interconnected via an Ethernet and using an 80486 PC to act as a Central Office System. This Central Office System provides speech/message storage for the phone terminals. It makes use of speech compression techniques to minimize the storage requirements. The speech compression techniques used as well as the field of speech coding in general are discussed