Satellite systems for personal and broadband communications [Book Review]

It might well have been in Sweden some 18 years ago during a direct broadcast satellite conference at the premises of the Royal Swedish Space Agency (Rymdbolaget) where this then-young reviewer had the privilege of hearing a less formal but impulsive (obviously copied from somewhere) statement given by an official government spokesman “Rubbish is rubbish even via satellite !” Well, now we are perhaps able to evaluate the situation more accurately and someone could point out that half of those sky channels transmit various sports events, the other half either noisy music or simplified 100-plus-show series of limited cultural content and satellite phone services are still a vague, yet costly, minority. So, in this sense the new satellites have, indeed, not given us much. Anyhow, we, as engineers, have learned to focus our efforts on the technological challenges and many of us have managed to develop suitable human filtering functions which make it easier to tackle the core problem whatever it is in the presence of diverting commercial interests. As we all have already seen from the terrestrial cellular phone applications or television broadcasting, telecommunications is a typical example of an area where business is the driving factor and engineering sciences have to serve it. When combined with space technology which has been, still is, and probably will forever be, an exceptionally expensive playground of activity communication is an even more money-driven task. The foreseen importance of satellite technology in the field of communications is clearly reflected by the high number of new systems which are planned for the current decade. Their expected usage is either directed toward mobile personal communications or to broadband multimedia, but will quite obviously see a fruitful mix of the two and a combination with some add-ons like navigation. The book for my review, Satellite Systems for Personal and Broadband Communications, authored by three enthusiastic scientists from the German Space Center (DLR) in Oberpfaffenhofen, brings one new European academic contribution into this topic area. The aul.hors, Erich Lutz, Markus Werner and Axel Jahn, work in the: Digital Networks group of the Institute for Communications and Navigation at DLR and have assembled and edited lheir research results, journal publications, and lecture notes into the form of a comprehensive textbook. The work is divided into three main parts with correlation to the three gentlemen involved. The first discusses the fundamentals of satellite communications, constellations, signal propagation, and, currently applied or expected transmission technologies and has four chapters. After this, part two, with an equal amount of chapters, wants to give a detailed treatment of satellite systems for slow-speed data transmission, but, actually, has material mostly related to multiple access, and, finally, the third part is devoted to multimedia via satellites where, unavoidably, the clock rates are much higher to cope with the requirements of internet-type movie clips; in practice this means ATM (Asynchronous Transfer Mode) and TCPAP (Transport Control Protocol / Internet Protocol) discussions. Some explanatory material is available in Appendices A through C where mathematics for beam-pointing aspects, fading statistics, and tabulated data of real or proposed system implementations (Iridium, Sky Station and Teledeslc) appear. In total, the book has over two hundred illustrations (mostly line drawings) and some sixty tables. More than 1,BO references are listed and an alphabetical index is provided, too. As the authors say, the book is intended to cover widely modern satellite communications. It has elements from pure radio frequency engineering, a lot of classical communications technology, ingredients from networks, and even some from e-business. Antennas, noise, modulation and coding, signaling, space engineering, and video formats are good examples of the diversity involved in the text. And everything is either spinning around the Earth along LEO (Low Earth Orbiting) or ME0 (Medium Earth Orbiting) orbits or may stay virtually stable above the #equator. This has been a considerable task for