Guest Editorial Direct-to-user Satellite Systems And ... - IEEE Xplore

IEEE JOURNAL ON SELECTED AREAS IN COMMUNICATIONS, VOL. 17, NO. 2, FEBRUARY 1999

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Guest Editorial Direct-to-User Satellite Systems and Technologies at Ka Band and Beyond

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HE need to develop new space technologies to face the emerging demand for wide-band services started to be evident in the late 1970’s. At that time, the main space agencies, including NASA in the United States, NASDA in Japan, ESA in Europe, and ASI in Italy, decided to pioneer the Ka band (20/30 GHz). In fact, this band provides a bandwidth almost five times larger than that available at either C band (4/6 GHz) or Ku band (11/14 GHz), the traditional spectrum resources for satellite communications. This bandwidth, however, was not put to use for a long time because of the large rain attenuation experienced by transmission in Ka band, and the associated cost of providing high-availability commercial services. But when the emphasis changed to providing direct-to-user (DTU) high-bandwidth services, with less stringent availability requirements, to users anywhere, and at any time, the era of broad-band communications provided by global systems with low-cost earth terminals capable of linking users around the world had been opened. The ETS-II (Engineering Test Satellite-Two), launched in 1977, was the first geostationary earth orbit (GEO) satellite in Japan, and was used to carry on propagation experiments up to 34 GHz. The first experimental satellite in Europe to carry Ka-band payloads was the Olympus satellite launched by the European Space Agency in 1989. Then, two regenerative satellites, the Italian ITALSAT satellite, launched in 1991, and the American ACTS (Advanced Communications Technology Satellite), launched in 1993, demonstrated the suitability of the new Ka-band technologies, and have become the cornerstones of the progress in this field. In fact, through extensive multiyear experimental campaigns, the ITALSAT and ACTS programs proved that DTU service requirements can be met by a single multispot GEO satellite, provided with on-board processing (OBP) capabilities, i.e., equipped with modems, baseband digital signal processors, memories, and switching stages on board. From this, it is a short step to conceive a constellation of GEO (or even nonGEO) satellites to allow full space connectivity through the use of intersatellite link (ISL) technologies at 60 GHz and/or optical frequencies. This double success fostered the design and development of many new systems internationally, aimed at introducing, in a few years, multimedia services via satellite with worldwide coverage. The first Ka-band systems are expected to become operational in the time window 2000–2005. ITU and FCC applications for Ka-band systems have been so many that it is Publisher Item Identifier S 0733-8716(99)01708-4.

virtually impossible to account for them here. The interested reader is referred to a conference dedicated to Ka-band utilization, being held yearly [1]–[4]. The sharp acceleration toward commercial applications at Ka band clearly indicates that this technology can be considered almost mature today. In the meanwhile, several space communications research programs are going on, aimed at preparing the ground for the exploitation of the extremely high-frequency (EHF) portion of the spectrum, to increase capacity and to provide higher data-rate services to portable/mobile terminals also. The objective of this Special Issue has been to probe the international community to better identify new trends and developments toward future advances in this fast-moving field. We selected 22 papers spanning topics from radio system aspects, including antennas and propagation topics, to issues such as OBP and ISL technologies, access and networking, protocols, and terrestrial/satellite hybrid networks. A broad view on research results and directions is thus provided, and we hope that this is useful both to the expert reader and to those who intend to approach this exciting field for the first time. I. OVERVIEW In the opening paper, Gargione et al. provide an overview of the services, technology, and system issues of the forthcoming systems at Ka band, with a glance toward the exploitation of higher frequency bands. II. ANTENNAS, PROPAGATION, AND FADE COUNTERMEASURES In the first paper of this section, Egami presents a new concept for power sharing among beams in a Ka-band satellite system intended for the case when many hundreds of beams are generated on board. Then, in their paper Pinder et al. compare measurement results collected through the ACTS with different rain attenuation models, in order to evaluate their merits in a desert climate zone. Celandroni and Potort`ı introduce a fractal process model to describe scintillation fading due to rain, which is based on a Brownian motion assumption. In the following paper, Cox and Coney consider an adaptive rain fade compensation protocol applied to a VSAT (very small aperture terminal) network and show the improvement achievable in bit-error rate experienced over a fairly long time period. Finally, Gremont et al. compare two predictive schemes for fade countermeasures at Ka band, showing that a variable detection margin strategy is more efficient than its fixed counterpart.

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III. RADIO SYSTEM PERFORMANCE The paper by Acosta et al. sets the point of the ACTS mission after four years of its operation, reporting on its technologies and experiments. The last three papers of this section concentrate on the performance of the code-division multiple-access (CDMA) strategy in the framework of satellite systems. In their paper, De Gaudenzi et al. study the CDMA capacity issue in the forward link of a multisatellite, multibeam network, and show the promising performance of a blind adaptive interference-mitigating receiver. The paper by Iossifides and Pavlidou provides an analysis of an M-ary orthogonal Walsh–Hadamard scheme with differential decoding, and shows the advantages in a fast fading channel such as the mobile satellite channel. In the last paper of this section, Valadon et al. present a synchronous CDMA air interface for a Ka-band satellite system, and evaluate its performance in terms of both bandwidth and power.

This section is closed by Koraitim and Tohm´e, who propose a resource allocation strategy which integrates CBR, bursty data, and best effort services at the multiple-access control layer of a Ka-band satellite system, present an analytical formulation for their strategy, and evaluate throughput and CBR blocking probability through simulation.

VII. HYBRID NETWORKS In their paper, ElBatt and Ephremides consider a service area covered by both a cellular system and a multispot satellite system, and address the problem of optimum partitioning of channels between the two, as well as the call admission strategy in this hybrid network. In the last paper of this Special Issue, Delli Priscoli deals with integration/interworking aspects of a multimedia satellite system and a terrestrial network (in particular, broad-band ISDN).

IV. ON-BOARD PROCESSING AND INTERSATELLITE LINK TECHNOLOGIES Boucheret et al. analyze the fast convolution filter bank for regenerative payloads in the case of variable bit-rate multimedia applications, and propose a technique to reduce complexity on board. The second paper of this section is concerned with optical ISL’s. Patel and Morris propose and analyze an adaptive phase alignment system in the postdetection stage of an aperture array in optical heterodyne receivers to reduce signal losses. V. ACCESS

AND

NETWORKING

In their paper, Birk and Keren study slotted ALHOA in the case of multiple channels, and show how to improve the capacity subject to the condition of meeting quality-ofservice requirements on maximum delay. Then, Farserotu and Prasad present a concept for broad-band wide-area networking via a Ka-band satellite based on the Internet Protocol (IP) over asynchronous transfer mode (ATM). The paper by Gerakoulis et al. evaluates the system throughput performance of a satellite-switched CDMA for different conditions of the channel assignment strategy. In the last paper of this section, Baiocchi et al. propose a satellite system architecture based on on-board switching and ATM, adopt a reactive congestion control technique appropriate to the satellite environment, and analytically evaluate its performance.

ACKNOWLEDGMENT The Guest Editors wish to take this opportunity to thank all of the authors, the reviewers, their collaborators, and—last but not least—Prof. J. Hayes, their IEEE mentor, who dedicated their precious time to let this Special Issue see the light. REFERENCES [1] [2] [3] [4]

Proc. Proc. Proc. Proc.

Ka Band Utilization Conf., Rome, Italy, Oct. 1995. 2nd Ka Band Utilization Conf., Florence, Italy, Oct. 1996. 3rd Ka Band Utilization Conf., Sorrento, Italy, Sept. 1997. 4th Ka Band Utilization Conf., Venice, Italy, Nov. 1998.

FRANCESCO VATALARO, Guest Editor Universit´a degli Studi di Roma “Tor Vergata” 00133 Roma, Italy

ANTHONY EPHREMIDES, Guest Editor University of Maryland College Park, MD 20742 USA

FRANK GARGIONE, Guest Editor Lockheed Martin Astro Space Newtown, PA 18940 USA

VI. PROTOCOLS To accommodate real-time traffic with an upper bound on end-to-end delay, Le Pocher et al. propose a simple first-in first-out protocol for use within a multimedia ATM satellite system. Then, Henderson and Katz address the problem of end-to-end performance (latency, error rate, etc.) of the transmission control protocol (TCP) when one or more satellites are included in the Internet link, and discuss both extensions to TCP and a new protocol. Minei and Cohen study the performance of the TCP/IP over a Ka-band satellite link, and propose a derived algorithm efficient in handling burst errors.

FRANCO MARCONICCHIO, Guest Editor Aqenzia Spaziale Italiana 00198 Roma, Italy

J. F. HAYES, J-SAC Board Representative


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Francesco Vatalaro (M’85–SM’91) received the Dr.Ing. degree in electronics engineering from the University of Bologna, Italy, in 1977. From 1977 to 1980, he was with Fondazione Bordoni, Pontecchio Marconi, Italy. Then, he was with FACE Standard, Pomezia, Italy, from 1980 to 1985. While with Selenia Spazio, Rome, Italy, he was Group Leader of Satellite Ground Segment Systems Engineering. In 1987, he became an Associate Professor of Radio Systems at the University of Roma Tor Vergata, Italy. In 1998, he was a Visiting Professor at the University of Southern California, Los Angeles, holding a spread-spectrum systems class. He has been responsible for several research contracts both at Italian national and European levels. He is the author of more than 70 original research papers published in international journals and in conference proceedings, one book (in Italian), and one international patent. His research interests include mobile and personal communications, satellite communications, spread-spectrum systems, and multipleaccess systems. Dr. Vatalaro was a co-winner of the 1990 “Piero Fanti” INTELSAT/Telespazio International Prize. He promoted the biannual European Workshop on Mobile/Personal Satcoms (EMPS) in 1994. He is a member of the Editorial Board of the International Journal of Satellite Communications. He is a member of the Scientific Committee of the “Istituto Internazionale delle Comunicazioni” (IIC), Genoa, Italy. He is the Chairman of the IEEE Joint Vehicular Technology/Communications Society Italy Chapter. He has been selected to be included in Who’s Who in the World, 1999 edition. He is a member of the AEI.

Anthony Ephremides (S’68–M’71–SM’77–F’84) received the B.S. degree from the National Technical University of Athens, Greece, in 1967, and the M.S. and Ph.D. degrees from Princeton University, Princeton, NJ, in 1969 and 1971, respectively, all in electrical engineering. He has been at the University of Maryland since 1971, and currently holds a joint appointment as Professor in the Electrical Engineering Department and the Institute of Systems Research (ISR). He is cofounder of the NASA Center for Commercial Development of Space on Hybrid and Satellite Communications Networks, established in 1991 at Maryland as an offshoot of the ISR. He was a Visiting Professor in 1978 at the National Technical University in Athens, Greece, and in 1979, at the EECS Department of the University of California, Berkeley, and at INRIA, France. During 1985–1986, he was on leave at M.I.T. and ETH, Zurich, Switzerland. Dr. Ephremides was the General Chairman of the 1986 IEEE Conference on Decision and Control in Athens, Greece. He has also been the Director of the Fairchild Scholars and Doctoral Fellows Program, an academic and research partnership program in satellite communications between Fairchild Industries and the University of Maryland. He won the IEEE Donald E. Fink Prize Paper Award (1992). He was President of the IEEE Information Theory Society (1987), and served on the Board of the IEEE (1989 and 1990). His interests are in the areas of communication theory, communication systems and networks, queueing systems, signal processing, and satellite communications.

Frank Gargione received the B.S.E.E. degree in electrical engineering in 1961 from Drexel University, Philadelphia, PA, and the M.S.E.E. degree also in electrical engineering in 1965 from the Moore School of the University of Pennsylvania. He is currently the Program Manager of the Advanced Communications Technology Satellite (ACTS) Program for Lockheed Martin Missiles and Space, Newtown, PA. Previously Manager of Systems and Operations, he has been involved with all aspects of the ACTS Project since its inception. In addition to his PMO responsibilities, he has assisted NASA in promoting the ACTS Experiment Program by presenting ACTS capabilities at seminars, conferences, technical meetings, and to prospective customers throughout the world. He has authored a number of technical papers on ACTS technology and applications, and is one of the founders of the Ka Band Utilization Conference which has become the major forum for the diffusion of satellite activities at Ka-band frequencies. His previous experience encompasses analog and digital design, hybrid circuit design, management of computer-aided design and test, and management of ground equipment design.

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Franco Marconicchio received the doctor’s degree in electronic engineering and in aerospace engineering, both from the University of Rome “La Sapienza.” In 1967, he was Assistant Professor of Satellite Communications at the University of Rome “La Sapienza,” and in 1968, he served as an Officer in the Italian Air Force. In 1969, he joined the Istituto Ricerche Spaziali (IRS) of the Italian Consiglio Nazionale delle Ricerche (CNR), in the SIRIO satellite mission management team. In 1971, he was responsible for the SIRIO spacecraft electronic subsystems, AOCS, range, and launch vehicle interfaces. He managed the national telecommunications projects and the Italian participation in the European Space Agency (ESA) telecommunications projects. He has been, since the beginning, the Program Director of the ITALSAT Italian national communications satellite program. Both ITALSAT satellite flight units were successfully launched in 1991 and 1996, respectively, and are operationally used. He was the Head of the Telecommunications and Applications Programs branch of the Italian Space Agency (ASI). He is a member of the Italian Delegation in the ESA. He is currently involved in the startup of the main projects included in the new 1998–2002 Italian Space Plan with responsibility for the strategic area.