Use of multiple antennas at both ends of Wireless links is the result of the
natural progression of more than four decades of evolution of adaptive
antenna technology. Recent advances have demonstrated that multiple-
input-multiple-output (MIMO) Wireless systems can achieve impressive
increases in overall system performance.
When we started thinking about writing this book, we had been working together for more
than five years on the borderline between propagation and signal processing.Therefore, it
is not surprising that this book deals with propagation models and design tools for MIMO
Wirelesscommunications.Yet, thisbookshouldconstitutemorethanasimplecombination
of these two domains. It hopefully conveys our integrated understanding of MIMO, which
results from endless controversial discussions on various multi-antenna related issues, as
well as various interactions with numerous colleagues. Obviously, this area of technology
is so large that it was beyond our aim to cover all aspects in details. Rather, our goal has
been to provide researchers, R&D engineers and graduate students with a comprehensive
coverage of radio propagation models and space–time coding techniques.
There are few technologies that have had a more profound effect on people’s lives
than mobile communications. As recently as twenty years ago no one had a mobile
phone, while today 1.4 billion men, women and children depend on them. This now
exceeds the number of landline users, where it took the preceding one hundred years
to reach the 1 billion mark. The ability to make mobile voice calls turns out to be the
answer to a deeply felt need across different cultures who simply want to
communicate.
This book is exclusively dedicated to WiMAX. The focus of the book is
on the applications of WiMAX networks, with delivery of multimedia
content to Wireless and mobile devices being the area of greatest atten-
tion. WiMAX has crossed a number of major milestones in the recent
past.
One of the very first books published on the social impact of the mobile phone
was Timo Kopomaa’s The City in Your Pocket: Birth of the Mobile Information Society.
The book, published in 2000, was based on research that Kopomaa had under-
taken for Nokia and Sonera as part of his doctoral studies in the Centre for Urban
and Regional Studies at the Helsinki University of Technology. The first line he
writes in the book is peculiar: ‘Mobile communication is not a serious matter’. By
this, we assume he is referring to a view of the world that would regard the mobile
phone as little more than an unremarkable fact of everyday life – a simple play-
thing for the young, or a productivity tool for the business executive and busy
parent.
In recent years, the research and developments in the area of RF and microwave
technologies have progressed significantly due to the growing demand for applica-
bility in Wireless communication technologies. Starting from 1992, Wireless com-
munication technologies have become quite mature. In the modern era of electronic
developments, design of Wireless handsets is an example of integration of many di-
verse skill sets. Classical books in the areas of microwave technology provide us
with an in-depth knowledge of electromagnetic fundamentals.
At recent major international conferences on Wireless communications,
there have been several sessions on beyond third generation (3G) or fourth
generation(4G)mobilecommunicationssystems,wheremodulation/demod-
ulation and multiplexing/multiple access schemes related to multicarrier
techniques have drawn a lot of attention. We often met at the conference
venuesandrealizedthatnobookcoveredthebasicsofmulticarriertechniques
to recent applications aiming at the 4G systems. Therefore, we decided to
write a book on multicarrier techniques for 4G mobile communications
systems.
The family of recent Wireless standards included the optional employment of Multiple-Input
Multiple-Output(MIMO)techniques.This was motivatedby the observationaccordingto the
classic Shannon–Hartley law that the achievable channel capacity increases logarithmically
with the transmit power. In contrast, the MIMO capacity increases linearly with the number
of transmit antennas, provided that the number of receive antennas is equal to the number
of transmit antennas. With the further proviso that the total transmit power is increased in
proportion to the number of transmit antennas, a linear capacity increase is achieved upon
increasing the transmit power, which justifies the spectacular success of MIMO systems.
Notwithstanding its infancy, Wireless mesh networking (WMN) is a hot and
growing field. Wireless mesh networks began in the military, but have since
become of great interest for commercial use in the last decade, both in local
area networks and metropolitan area networks. The attractiveness of mesh
networks comes from their ability to interconnect either mobile or fixed
devices with radio interfaces, to share information dynamically, or simply to
extend range through multi-hopping.
In case you haven’t noticed, multimedia communication over IP and Wireless net-
works is exploding. Applications such as BitTorrent, used primarily for video
downloads, now take up the lion’s share of all traffic on the Internet. Music file
sharing, once on the legal cutting edge of massive copyright infringement on col-
lege campuses around the world, has moved into the mainstream with signifi-
cant legal downloads of music and video to devices such as the iPod and nu-
merous other portable media players.