Wireless Flexible Personalised Communications

by Luis M. Correia

Overview

Recent years have witnessed an explosion of new operators and customers of cellular mobile communications and the importance of wireless/mobile communications in today's telecommunications industry is indisputable.
The Final Report of COST 259, 'Wireless Flexible Personalised Communications' is the result of extensive work, performed by more than 200 European researchers from more than 90 institutions (universities and companies) in the area of mobile radio.
—Provides a discussion on the evolution of wireless/mobile communications focusing on the use of data and multimedia, and consequently broadband communications
—Examines the radio systems aspects of future wireless communication systems, concentrating primarily on physical layer issues and including assessments of OFDM and CDMA
—Presents radio propagation and adaptive antennas, and provides a thorough understanding of the mobile radio channel
—Discusses the radio network aspects for the improvement and optimisation of the existing 2G systems and the planning of UMTS/IMT2000
—Explains the design and implementation of UMTS and new techniques for future wireless broadband communication systems
Due to the broad and comprehensive range of topics covered in this book it will appeal not only to engineers working within the GSM industry but also to those involved in UMTS and to researchers working on the next generation of mobile systems.

Product Details

ISBN-13:	9780471498360
Publisher:	Wiley
Publication date:	06/08/2001
Pages:	484
Product dimensions:	6.89(w) x 9.70(h) x 1.17(d)

About the Author

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

Read an Excerpt

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 [GSM00] 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 [IMT00], 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) [UMTS00], 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 nonexistence 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 [RACE00]: it is a cellular mobile system, thus covering both indoor and outdoor 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 initiative from telecommunications and computer manufacturers (which operators have also joined), Bluetooth [Blue00], 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.

Table 1.1: Evolution of data rates in cellular mobile communication systems....

...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....

Figure 1.1.1: Evolution of data rates in cellular mobile communication systems.

...In the very near future, mobile multimedia will be available via UNITS [UMTS00], which will enable users to exchange information at a data rate up to 2 Mb/s. Many people involved in the development of UMTS today hope that mobile multimedia will have the same success (and consequently expansion rate) experienced by mobile phones. It is not at all clear that this will happen, for reasons that will be mentioned later. It has after been suggested that this will depend on the definition of one or several 'killer applications' that will boost wireless multimedia services, thus creating conditions for that success. This is especially true for WBCS, due to the very high data rates involved (by today's standards), and the argument arises that there is no need to develop systems for non-existent applications. However, again taking the example of the computer industry, one can present arguments that contradict that conservative perspective: until some years ago, operating systems were based on line commands (e.g. VMS, DOS, Unix, and so on), which meant that the user had to memorise a lot of these instructions in order to use the computer; this situation was a barrier to the expansion of computers as a mass market, since one of the basic rules for this (ease of use) was not applied. Then Apple launched the windows-based Mac operating system, which was followed by Microsoft, and the rest of the story is well known. It is easy to find quotations from some years ago, coming from very important people (like company chairmen), stating that the computer industry would never be a mass market, or that a few computers would be enough for the whole world; similar statements on the lack of a future for mobile communications can also be found. As far as WBCS are concerned, perhaps the applications requiring these high data rates are still to be found, or perhaps the natural evolution of data rates over mobile systems (resulting from the evolution of existing applications) will reach those values in the future, as in the case of software and hardware in computers.

Another important aspect in the evolution of mobile communications is that new players are coming into the business. The business of manufacturers is different from that of operators, although they depend on each other. The former make money by selling either equipment to operators or mobile phones to customers, while the latter get their profit by selling airtime. The introduction of new features and systems is a closed circle situation: operators need equipment from manufacturers to put those services into function; in turn, manufacturers need operators to launch these novelties to sell phones to customers (even to those that already have a phone, but who are willing to pay for extra features). Moreover, manufacturers will only make such equipment if they are sure that operators will buy it, i.e. that they are willing to implement these new features or systems. This situation, which is not specific to telecommunications, can pose some problems in the development of WBCS: almost everyone in the business must be really convinced that these systems have a future, in order to start putting some real effort into their development, and this is still not the case today. Of course, before getting to WBCS, one has still to see what will happen to wireless multimedia applications to be developed within the incoming third generation cellular systems.

However the telecommunications business is more and more becoming one in which other companies besides operators and manufacturers have a role to play. The success of WBCS will depend very much on the existence of mass market multimedia services that will enable an increasing number of people to be seduced by them. This is the role of the content and applications providers. One can foresee a scenario in the future where many services that are not even available today on the Internet will be in common use in the future on a wireless multimedia terminal. One can already find many videos presenting visionary views of wireless multimedia services; two of the first that were developed are mentioned in what follows. One, produced by Hewlett-Packard [HP00], shows a disaster scenario resulting from an earthquake, where wireless multimedia terminals are used by...

Table of Contents

Preface vii

Table of Contents ix

List of Acronyms xii

I Introduction 1

1.1 Evolution of Wireless/Mobile Communication 1

1.2 Description of COST 259 7

1.3 References 12

2 Radio Systems Aspects 13

2.1 OFDM and Frequency Domain Techniques 14

2.1.1. Introduction 14

2.1.2. Alternative forms 17

2.1.3. Modulation and demodulation 24

2.1.4. Channel coding 26

2.1.5. Multiple access schemes 29

2.1.6. Amplitude limitation 29

2.1.7. Intercell interference 30

2.1.8. Synchronization 31

2.2 CDMA 43

2.2.1. Introduction 43

2.2.2. RAKE receivers 44

2.2.3. Linear and non-linear interference cancellation 45

2.2.4. Coding and modulation 47

2.2.5. Smart antennas 49

2.2.6. Parameter estimation 50

2.2.7. Demonstrators 51

2.2.8. Summary and conclusions 51

2.3 Modulation and Coding 51

2.3.1. Linear modulation 52

2.3.2. Non-linear modulation 53

2.3.3. FEC coding techniques 55

2.3.4. Equalization 58

2.3.5 Adaptive coding and modulation 59

2.4. DECT and Adaptive Sampling 62

2.4.1. Introduction and motivation 62

2.4.2. Principle of adaptive sampling 63

2.4.3. Determination of optimum sampling time 64

2.4.4. Non-linear receiver structures 65

2.4.5. Summary and conclusions 66

2.5 References 66

3 Antennas and Propagation 77

3.1. General Aspects of Propagation 78

3.1.1. Statistical and empirical modelling 79

3.1.2. Propagation measurements and channel sounders 112

3.1.3. Deterministic modelling 132

3.2 Directional Channel Modelling 148

3.2.1. Modelling concept 149

3.2.2. Outdoor measurements results 160

3.2.3. Indoor measurements results 171

3.2.4. Parameter settings 178

3.3. Smart Antennas 194

3.3.1. Introduction 194

3.3.2. Space and antenna diversity 197

3.3.3. Polarization diversity 201

3.3.4. Antenna arrays 203

3.4. Millimetre-wave Propagation 223

3.4.1. Path loss modeling 223

3.4.2. Wideband channel modeling 229

3.4.3. Impact of shaped lens antennas on the ChIR and cell coverage 239

3.5 Antennas for Mobile Phones 251

3.5.1 Communications performance 251

3.5.2. Standardized phone measurements 261

3.6. References 277

4 Network Aspects 307

4.1. Compatibility and Spectrum Efficiency 308

4.1.1. Spectral compatibility 308

4.1.2. Spectrum efficiency 314

4.2. Channel Allocation Strategies 327

4.2.1. Introduction 327

4.2.2. Concise data for automated frequency planning 330

4.2.3. Fixed channel allocation using graph colouring 335

4.2.4. Fixed channel allocation maximizing assigned TRXs 336

4.2.5. Fixed channel allocation minimizing interference 337

4.2.6. Distributed dynamic channel allocation 346

4.2.7. Benchmarking frequency allocation strategies 348

4.3. Cellular Aspects 359

4.3.1. Cell modelling 359

4.3.2. Tele-traffic engineering 363

4.3.3. Hot spot location 373

4.3.4. Mobility models 377

4.4. Network Optimization 386

4.4.1. Handover, power control and direct retry 386

4.4.2. Frequency hopping for capacity enhancement 398

4.4.3. Quality and capacity enhancement by adaptive techniques 407

4.5. Planning Methods and Tools 412

4.5.1. Geographic data 412

4.5.2. Methods for optimized planning 415

4.5.3. UMTS planning 419

4.6 Efficient Protocols for High Data Rates 426

4.6.1. High data rate protocols: general aspects 427

4.6.2. Wireless ATM 428

4.6.3. Packet reservation multiple access 429

4.7 References 433

Annex I – List of Contributors 451

Annex II – List of Participating Institutions 453

Index 457

Editorial Reviews

"The final report of the COST 259 project that explored radio system aspect for flexible personalized communication capable of delivering...services on different bandwidths...new modeling techniques...related planing tools...across a number of different environments." (SciTech Book News, Vol. 25, No. 3, September 2001)

From the Publisher

The final report of the COST 259 project that explored radio system aspects for flexible personalized communication capable of delivering different services on different bandwidths, and new modeling techniques and related planning tools for ensuring the continuity of services delivered by networks of widely different capabilities and structures across a number of different environments. The first of the three chapters deals with radio systems aspects of future wireless communications systems, focusing primarily on physical layer issues. Smart antennas, propagation modeling and spatial channel models are then addressed. The final chapter considers network aspects, with an eye to the initial standardization of the UMTS/IMT2000 and improvement of existing second generation systems. Annotation c. Book News, Inc., Portland, OR (booknews.com)

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