Wireless Personal Communications 10: 1–2, 1998. © 1998 Kluwer Academic Publishers. Printed in the Netherlands.

Preface

Initially mobile communications were about phoning people anytime anywhere; voice was then the only signal to be carried, which was perfectly suitable for analogue systems. With the development of communication systems in general (e.g., the generalisation of computer networks and fax machines), this type of mobile systems soon was obsolete, and more powerful ones were needed. The second generation of mobile communication systems, already based on a digital technology, came as a solution to issues that were relevant at the time they were developed, i.e., among other things to enable access to the Internet and to transmit faxes, without questioning the data rates; the question was really to have access to those services and not at what speed it was done. Of course the race went, people got used to use nonvoice services in the fixed network, and started questioning the speed at which these services were available in the mobile one. On the other hand, the wireless era began to spread to other applications, like Local Area Networks (LANs). The increasing role of multimedia and computer communications in today’s telecommunications has pushed wireless and mobile systems to cope with higher data rates. At the time this special issue is being prepared, an enormous effort is being done on international standardisation bodies, in order to achieve a world standard for the third generation of mobile communication systems, usually designated by Universal Mobile Telecommunications System (UMTS), which will enable users to transmit information with data rates up to 2 Mb/s. It is obvious that the race will not stop here, and not only new services are being foreseen for the future but new systems capable of supporting these services are being investigated as well. Broadband communications, those with data rates greater than 2 Mb/s, are emerging and being extended to non-wired systems, with applications foreseen for example in Broadband Wireless LANs (BWLANs), or Mobile Broadband Systems (MBSs). Due to the large bandwidths involved, carrier frequencies are going up once more, being allocated in the micro and millimetre wave bands. These new systems are still on a very early stage of development, but some initial results are already appearing, and an increasing interest is being devoted to them by the research community all around the world. This special issue on Wireless Broadband Communications (WBCs) was initially thought as an opportunity to put together research results in an area that is facing today a large growth, and that will be very important in the future. We think that these objectives were totally fulfilled. A total of 12 papers were submitted, from which 8 are published here (the others were either withdrawn or rejected by the reviewers). These papers cover topics in a large number of areas (e.g., antennas, propagation, protocols, traffic, system performance, and multiple access techniques), which shows that the various aspects of WBCs are being addressed already. Moreover, these papers come from Europe, Asia and North America, thus proving that the interest on the development of WBCs is not a local or regional phenomenon, rather being faced at a global perspective. An acknowledgement is due to the authors who submitted papers, contributing to the success of this special issue, to the reviewers, who assisted in guaranteeing the necessary quality of the final papers to be published, to Prof. Ramjee Prasad, who made the invitation to

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Preface

the guest editors, and to Mr. Mike Casey, who gave all the necessary support for the editing issues. LUIS M. CORREIA MASAO NAKAGAWA

Luis M. Correia was born in Portimao, Portugal, in 1958. He received his Ph.D. from IST – Technical University of Lisbon, Portugal, in 1991, where he is currently a Professor in the Department of Electrical Engineering and Computer Science. His research work is focused in mobile communications, in the areas of wave propagation, antenna design, traffic modelling and cellular planning. Since some time he has been involved in research at the European level, in projects within the frameworks of RACE, ACTS and COST; presently he is the Chairman of COST 259 (Wireless Flexible Personalised Communications). He has served as Auditor/Evaluator in the ACTS and ESPRIT European programmes. He authored several papers and communications in journals and conferences, and has served as reviewer as well. Masao Nakagawa (M’81) was born in Tokyo, Japan, on November 19, 1946. He received the B.E., M.E., and Ph.D. degrees from Keio University, Yokohama, Japan, all in electrical engineering, in 1969, 1971, and 1974 respectively. Since 1973, he has been with the Department of the Electrical Engineering, Keio University, Hiyoshi, Kohoku-ku, Yokohama, Japan, where he is now Professor. His research interests are in spread spectrum communication, consumer communication, mobile communication, digital broadcasting and wireless home link. He was the Executive Committee Chairman of the International Symposium on Spread Spectrum Techniques and Applications held in Yokohama in 1992, the Program Chairman of the International Symposium on Information Theory and Its Applications held in Sydney in 1994, and one of the Guest Editors of the Special Issue on Code Division Multiple Access Networks I, II in 1994, III, IV in 1996 of IEEE Journal on Selected Areas in Communications. He is one of the Area Editors of Wireless Personal Communications. He was the Chairman of the Study Group of Spread Spectrum Technology of the Institute of Electronics Information and Communication Engineers. Dr. Nakagawa received IEEE Consumer Electronics Society Chester Sall Award in 1990.