An Overview of the Satellite and Space Communications Committee
By Walter J. Ciesluk and Iwao Sasase, Past Chairs of the SSC Committee
The Satellite and Space Communications (SSC) Committee has provided a forum for technical interchange among those working in this field for nearly 40 years. It began in the early 1960’s soon after it was recognized that the rocket capabilities demonstrated by the Soviet Union and United States in the late 1950’s could readily be used to launch communications satellites. From that time, the development and impact of satellite communications has been revolutionary. In the early days, the major activity was associated with the business, political and technical issues associated with the development and introduction of the first communications satellites. The technical community was occupied with the tradeoff studies associated with satellite orbits, frequency bands and link design. However, the first communications satellites came along quickly with low earth orbit launches of Telstar and Relay in 1962, the first synchronous orbit satellite, Syncom, in 1963, and the launch of INTELSAT 1 and MOLNIYA 1 in 1965. From that time, the field of satellite communications has continued to grow rapidly. Satellites became dramatically larger, capable of increased capacity, and employed rapidly developing light weight electronics technology, spacecraft control and power generation and storage devices. Significant development went into sophisticated space-borne regional and spot-beam dual polarized antennas at both C- and Ku-band to increase payload capacity through frequency reuse techniques. Next, Very Small Aperture Terminal (VSAT) networks and applications, and direct broadcast satellite systems and technology were introduced. Quickly, the exploitation of the Ka band frequencies for future growth became important topics within the satellite communications community. During the 70s and 80s, major engineering efforts were devoted to the development or higher power amplifiers, lighter weight and improved performance microwave filters and circuit switches, and electric power generation and storage devices which contributed to larger communications satellite payloads that fit the launch constraints of available launch vehicles. Eventually, systems to provide communications services to mobile terminals, e.g., ships, land vehicles and aircraft were developed. These systems exploited one of the major attributes of communications satellites, that is the capability to offer wireless services over a large service area.
Today, communications satellites carry about one third of voice and essentially all international television traffic. Significant advances in video compression and data protocol enhancement technology have made new and many previously very expensive satellite communications services such as digital direct broadcast satellite (DBS), digital direct-to-home (DTH), and Internet Access available at lower cost. At the same time, we are entering a new and potentially revolutionary era in satellite communications. A large number of commercial systems are being planned and introduced to provide a wide array of voice, data, and video services that promise to radically change global telecommunications. These include narrow band systems, such as Ellipso, Globalstar, ICO, Iridium, and ECCO, which intend to provide cellular telephone-like services in L/S-band. There are also a host of wide band systems being planned for Ka-band, such as Astrolink, Spaceway and Teledesic, which intend to provide multimedia services to desktop computer-size terminals starting around 2000. Both the narrow band and wide band systems appear attractive because they offer much higher capacity and relatively low user costs compared to traditional systems. In the latter part of 1997, several companies announced proposals to build satellite systems in the Q and V bands to supplement the Ka-band wide band systems now in various stages of development.
The importance and excitement of these new satellite initiatives was featured in two recent magazine articles. An article in the March 1998 issue of the IEEE Spectrum magazine entitled, “Satellites Free the Mobile Phone, by Barry Miller, describes the emerging L/S band personal communications satellite systems. In an April 1998 Scientific American article entitled, “New Satellites for Personal Communications”, John V. Evans profiled all the new voice-oriented and data oriented personal communications systems as well as the systems planning for use of the frequencies beyond Ka band.
The committee has had the opportunity to experience the rapid and revolutionary developments that have occurred in the field of satellite and space communications over the years and today continues to provide a forum to facilitate technical interchange among those working in the field. The current emphases are on the evolution of new satellite and space-based systems and on the applications of emerging technologies to satellite and space communications. Because of the broad range of the technologies involved, and the necessity of integrating and interfacing satellite communications with other networks, the committee has attempted to develop liaisons with other committees such as Multimedia Communications, Personal Communications (PC), and Communication System Integration and Modeling (CSIM). In addition the committee maintains a keen interest in the development and maintenance of standards for communication and is particularly concerned with those that effect satellite and space communications. Specific technologies of current interest include:
- Satellite based personal and mobile communications systems
- ISDN and BISDN satellite applications andnetworks
- Advanced modulation/demodulation and on-board signal processing
- Direct broadcast and high definition television
- Very small aperture and handheld satellite systems and networks
- Ka/Q/V band satellite communications systems
The committee has also encouraged the publication of progress in the Transactions on Communications and The Journal on Selected Areas In Communications (JSAC). In fact the inaugurating, January 1983 issue of the JSAC was devoted to Digital Satellite Communications and this has been followed by five other special issues on communications satellite areas.
The committee continues to meet semi-annually at the ICC and Globecom conferences and to sponsor technical sessions on satellite communications systems and technology. The committee also publishes semi-annually the “SSC Newsletter”. In recent years, the committee has been striving to provide information about the new systems and developments via workshops. At recent Globecom conferences, the committee has held workshops on “Future Satellite Communications Systems”. These workshops reviewed several mobile and fixed satellite communication systems being developed for use in the year 2000 and beyond, and focused on concepts, architectures, multiple access, operation, performance and network management for the new satellite communication systems. A workshop on “Audio and Video Compression Technology for Satellite Communications” was also organized for a recent ICC conference and focused on the revolutionary advances in data compression algorithms and technology associated with audio and video signal processing, and their impact on satellite direct broadcast TV, distance learning, video conferencing, news gathering, tele-medicine, and digital audio broadcasting.
The committee is currently collaborating with the CSIM committee in organizing a workshop on “Satellite Communications Architectures and Networks” for ICC’99 in Vancouver. The objective of this workshop is to examine the architectures, applications, and technologies of satellite networks in their role in the current information services infrastructure as well as in their future role when new commercial narrow-band and wide-band satellite communications systems become ubiquitous. It will address important themes and topics such as TCP/IP, Internet, ATM, and multicasting over satellite; Digital Video Broadcasting; integration of satellite and terrestrial networks; new developments in access technology and protocols; and emerging low earth orbit SATCOM.
Clearly, the field of satellite communications continues to grow rapidly and remains interesting and exciting. We encourage all who are interested in this field to join our committee. Visit our website (http://www.comsoc.org/socstr/techcom/ssc/) where you can get information on events and upcoming meetings, and interact with committee officers and members.