A decade ago, I first wrote that people moved, and networks needed to adapt to the
reality that people worked on the go. Of course, in those days, wireless LANs came
with a trade-off. Yes, you could use them while moving, but you had to trade a great
deal of throughput to get the mobility. Although it was possible to get bits anywhere,
even while in motion, those bits came slower. As one of the network engineers I worked
with put it, “We’ve installed switched gigabit Ethernet everywhere on campus, so I
don’t understand why you’d want to go back to what is a 25-megabit hub.” He un-
derestimated the allure of working on the go.
The core thrust of architecture has been to define core business requirements,
and then construct the IT solution to meet those requirements, typically as
instances of software. while this seems like a simple concept, many in enter-
prise IT went way off course in the last 10 to 15 years.
The past two decades have witnessed the introduction and unprecedented growth of cellular
mobile telephony and wireless communications. Numerous wireless access technologies
have been introduced in the mobile communications market. while some have flourished
and formed the basis of successful manufacturing and network operator businesses, many
have lived only for a short time and disappeared.
Cognitive radio has emerged as a promising technology for maximizing the utiliza-
tion of the limited radio bandwidth while accommodating the increasing amount of
services and applications in wireless networks. A cognitive radio (CR) transceiver
is able to adapt to the dynamic radio environment and the network parameters to
maximize the utilization of the limited radio resources while providing flexibility in
wireless access. The key features of a CR transceiver are awareness of the radio envi-
ronment (in terms of spectrum usage, power spectral density of transmitted/received
signals, wireless protocol signaling) and intelligence.
Mobile communication has gained significant importance in today’s society. As
of 2010, the number of mobile phone subscribers has surpassed 5 billion [ABI10],
and the global annual mobile revenue is soon expected to top $1 trillion [Inf10].
while these numbers appear promising for mobile operators at first sight, the
major game-changer that has come up recently is the fact that the market is
more and more driven by the demand for mobile data traffic [Cis10].
while teaching classes on digital transmission and mobile communications for
undergraduate and graduate students, I was wondering if it would be possible to
write a book capable of giving them some insight about the practical meaning of the
concepts, beyond the mathematics; the same insight that experience and repetitive
contact with the subject are capable to construct; the insight that is capable of build-
ing the bridge between the theory and how the theory manifests itself in practice.
Fundamentals of WiMAX was consciously written to appeal to a broad audience, and to be of
value to anyone who is interested in the IEEE 802.16e standards or wireless broadband networks
more generally. The book contains cutting-edge tutorials on the technical and theoretical under-
pinnings to WiMAX that are not available anywhere else, while also providing high-level over-
views that will be informative to the casual reader.
The writing of this book was prompted by two main developments in wireless
communications in the past decade. First is the huge surge of research activities in
physical-layer wireless communication theory. while this has been a subject of study
since the 60’s, recent developments in the field, such as opportunistic and multi-input
multi-output (MIMO) communication techniques, have brought completely new per-
spectives on how to communicate over wireless channels.
Providing QoS while optimizing the LTE network in a cost efficient manner is
very challenging. Thus, radio scheduling is one of the most important functions
in mobile broadband networks. The design of a mobile network radio scheduler
holds several objectives that need to be satisfied, for example: the scheduler needs
to maximize the radio performance by efficiently distributing the limited radio re-
sources, since the operator’s revenue depends on it.
This book is intended to help electric power and telephone company
personnel and individuals interested in properly protecting critical tele-
communications circuits and equipment located in high voltage (HV)
environments and to improve service reliability while maintaining safe
working conditions. Critical telecommunications circuits are often
located in HV environments such as electric utility power plants,
substations, cell sites on power towers, and standalone telecommuni-
cations facilities such as 911 call centers and mountaintop telecom-
munications sites.
