Wireless Flexible Personalised Communications: COST 259: European Co-operation in Mobile Radio Research - Hardcover

Über die Autorin bzw. den Autor

Luis M. Correia is the author of Wireless Flexible Personalised Communications, published by Wiley.

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1 Introduction - Luis M. Correia

This chapter contains a discussion on the evolution of mobile communications, as well as a brief description of the activities of COST 259. For the former, a perspective on the evolution of mobile communications is given, focusing on the use of data and multimedia, and consequently on broadband communications. The latter intends to present to all those that are not familiar with the COST framework in general, and with COST 259 in particular, information on the way it worked and on the technical areas that were addressed.

1.1 Evolution of Wireless/Mobile Communications

The importance of wireless/mobile communications in today's telecommunications industry in general is indisputable. The last few years has witnessed an explosion of new operators and customers of cellular mobile communications in many countries of the world. This is partially due to the internal competition introduced in those countries, and partially because of the success of GSM [GSMOO] at the worldwide level (allowing international roaming and many other features that, in some countries, were introduced before the fixed network ones, among other reasons). This success has created the necessary momentum in the whole telecommunications industry to speed up the development of third generation mobile communication systems, IMT-2000 [IMTOO], expected to be operational in two years from now, for which standardisation is presently being finished in international bodies .

No justification is needed today as to why Research & Development should be carried out on UMTS (the European approach to IMT-2000) [UMTSOO], but many people still argue about the need for studying/developing Wireless Broadband Communication Systems (WBCS) (no distinction is drawn here between 'wireless' and 'mobile' systems), those providing user data rates higher than 2 Mb/s and up to 155 Mb/s (for the time being), which can be seen as belonging to a fourth generation. Although, at the present time, there is no clear view of what WBCS will be, they will probably emerge as a combination of two different existing concepts: WLANs and cellular mobile systems. Many things need to be defined, especially which applications will be supported; many people argue that there is no need for such systems, due not only to the evolution of compression techniques, but also to the non-existence of applications really requiring such high data rates. Nevertheless, some things are already generally accepted, one of them being that WBCS will work at the millimetre waveband (or at the high microwave one, at least), since such high data rates cannot be accommodated at lower frequencies.

The concept of a WLAN is well known today: basically, it provides a wireless connection to LAN users, usually considered to work indoors. WLANs by themselves are not part of WBCS, since one can have WLANs at very low rates, but once they achieve data rates higher than 2 Mb/s, one can talk about BWLANs (Broadband WLANS), thus making them part of the group. The idea of Mobile Broadband Systems (MBS) is not as well known, having been launched in the European R&D framework of RACE [RACEOO]: it is a cellular mobile system, thus covering both indoor and out door scenarios, enabling users to have a mobile extension of B-ISDN (Broadband-ISDN). The differences between the two concepts, assuming the common definitions that are used today for both basic systems, are also well known, and will not be listed here. Bearing in mind some of the services and application scenarios that are foreseen for WBCS, which will be addressed later on, it seems that these systems really need to present themselves as a merger of the two concepts, so throughout this chapter no distinction will be made between them. An example of this merger is the recent initiativefrom telecommunications and computer manufacturers (which operators have also joined), Bluetooth [BlueOO], with the goal to promote the convergence between the computer and mobile communications worlds.

The development of mobile communications is intrinsically associated with the development of data transmission on mobile networks, and this is in fact what makes the difference between second and third generation systems: the former were designed for voice, while the latter are being designed for data. An exercise can be carried out on the evolution of data rates in the mobile communications industry. Considering the existing second generation cellular systems, and the incoming ones (Table 1.1.1), one can see that there is a clear trend to increase the user data rate, thus showing that wireless data communications are in fact still in their early days. A similar trend exists for WLANs and other wireless communication systems. One can also plot the maximum data rate versus the starting date of commercial operation (actual or foreseen) for cellular systems, Figure 1.1.1: a linear trend (when data rates are plotted on a log scale) is observed, even taking into consideration the forecasts for the next few years. If this trend is followed, services at 155 Mb/s will be operational around year 2010; whether this will happen or not remains to be seen.

The need for high data rates has been addressed in [CoPr97]. The reasons then given for that need became stronger, and today they make more sense than ever. The example of the computer industry was shown, demonstrating that memory and clock have evolved in a way that would not have been foreseen some years ago; that evolution has continued, with the same trend, showing that one should not be too conservative with regards to the needs and perspectives of future systems. As far as high data rates for mobile systems are concerned, one of the basic issues is to find services that will require the transmission of information at such values; more and more, Internet and multimedia configure themselves as being part of this group of services. Internet access via PDC/PHS I-mode [PDC00], [PHS00], and GSM WAP [GSM00] are certainly in this direction.