Mobilenetworkoperatorswillmeetmanychallengesinthecomingyears.Itisexpectedthatthe
numberofpeopleconnected,wirelineandwireless,willreachfivebillionby2015.Atthesame
time, people use more wireless services and they expect similar user experience to what they
can now get from fixed networks. Because of that we will see a hundred-fold increase in
network traffic in the near future. At the same time markets are saturating and the revenue per
bit is dropping.
Due to the asymmetry between the amount of data traffic in the downlink and
uplink direction of nowadays and future wireless networks, a proper design of the
transceivers in the broadcast channel is inevitable in order to satisfy the users’
demands on data rate and transmission quality. This book deals with the optimi-
zation-based joint design of the transmit and receive filters in a MIMO broadcast
channel in which the user terminals may be equipped with several antenna ele-
ments.
In the past few decades, a technological revolution has occurred that has changed
the way we live in dramatic ways. This technological revolution is the result of
the emergence and evolution of a wide variety of new wireless networking tech-
nologies. Now people using these technologies are able to access the network and
control many applications at will with their handheld devices anywhere, anytime.
Although these technologies have made a long lasting impact in the revolution, it
has also opened up various challenging issues which are yet to be resolved to make
them more efficient and cost-effective.
Optical wireless communication is an emerging and dynamic research and development
area that has generated a vast number of interesting solutions to very complicated
communication challenges. For example, high data rate, high capacity and minimum
interference links for short-range communication for inter-building communication,
computer-to-computer communication, or sensor networks. At the opposite extreme is
a long-range link in the order of millions of kilometers in the new mission to Mars
and other solar system planets.
Without doubt, the age of information communications is upon 11s. The rapid
pace of technological advancement in digital data communications can be wit-
nessed in a multitude of applications in our day-to-day existence. In recent
years, the widespread proliferation of wireless digital cornmunications hass been
readily accepted by the general population worldwide; this is nearly unpa~rallcled
in few other human scientific achievements in terms of scope and speed of devel-
opment.
This book is a result of the recent rapid advances in two related technologies: com-
munications and computers. Over the past few decades, communication systems
have increased in complexity to the point where system design and performance
analysis can no longer be conducted without a significant level of computer sup-
port. Many of the communication systems of fifty years ago were either power or
noise limited. A significant degrading effect in many of these systems was thermal
noise, which was modeled using the additive Gaussian noise channel.
In a cellular communication system, a service area or a geographical
region is divided into a number of cells, and each cell is served by an
infrastructure element called the base station through a radio interface.
Management of radio interface related resources is a critical design
component in cellular communications.
By inventing the wireless transmitter or radio in 1897, the Italian physicist Tomaso
Guglielmo Marconi added a new dimension to the world of communications. This
enabled the transmission of the human voice through space without wires. For this
epoch-making invention, this illustrious scientist was honored with the Nobel Prize
for Physics in 1909. Even today, students of wireless or radio technology remember
this distinguished physicist with reverence. A new era began in Radio
Communications.
The first question most readers of an O’Reilly book might ask is about the choice of the
cover animal. In this case, “why a duck?” Well, for the record, our first choice was a
unicorn decked out in glitter and a rainbow sash.
That response always gets a laugh (we are sure you just giggled a little), but it also brings
to the surface a common perception of software-defined networks among many expe‐
rienced network professionals. Although we think there is some truth to this perception,
there is certainly more meat than myth to this unicorn.
The serious study of the practice of how to determine the appropriate content of a
specification is a seldom-appreciated pastime. Those who have the responsibility to
design a product would prefer a greater degree of freedom than permitted by the con-
tent of a specification. Many of those who would manage those who would design
a product would prefer to allocate all of the project funding and schedule to what
they consider more productive labor. These are the attitudes, of course, that doom a
project to defeat but they are hard to counter no matter how many times repeated by
design engineers and managers. A system engineer who has survived a few of these
experiences over a long career may retire and forget the past but we have an endur-
ing obligation to work toward changing these attitudes while trying to offer younger
system engineers a pathway toward a more sure success in requirements analysis and
specification publishing.
