Radio frequency spectrum is a scarce and critical natural resource that is utilized for
many services including surveillance, navigation, communication, and broadcast-
ing. Recent years have seen tremendous growth in the use of spectrum especially by
commercial cellular operators. Ubiquitous use of smartphones and tablets is one
of the reasons behind an all-time high utilization of spectrum. As a result, cellular
operators are experiencing a shortage of radio spectrum to meet bandwidth
demands of users. On the other hand, spectrum measurements have shown that
much spectrum not held by cellular operators is underutilized even in dense urban
areas. This has motivated shared access to spectrum by secondary systems with no
or minimal impact on incumbent systems. Spectrum sharing is a promising
approach to solve the problem of spectrum congestion as it allows cellular operators
access to more spectrum in order to satisfy the ever-growing bandwidth demands of
commercial users.
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.
Recent advances in wireless communication technologies have had a transforma-
tive impact on society and have directly contributed to several economic and social
aspects of daily life. Increasingly, the untethered exchange of information between
devices is becoming a prime requirement for further progress, which is placing an
ever greater demand on wireless bandwidth. The ultra wideband (UWB) system
marks a major milestone in this progress. Since 2002, when the FCC allowed the
unlicensed use of low-power, UWB radio signals in the 3.1–10.6GHz frequency
band, there has been significant synergistic advance in this technology at the cir-
cuits, architectural and communication systems levels. This technology allows for
devices to communicate wirelessly, while coexisting with other users by ensuring
that its power density is sufficiently low so that it is perceived as noise to other
users.
Welcome to the world of wireless communications and the logical extension
to the broadband architectures that are emerging as the future of the
industry. No aspect of communications will be untouched by the wireless
interfaces;no part of our working environment will be left untouched either.
As the world changes and the newer technologies emerge, we can expect to
see more in the line of untethered communications than in the wired inter-
faces.
A wireless ad-hoc network is a wireless network deployed without any infrastructure. In
such a network, there is no access point or wireless router to forward messages among the
computing devices. Instead, these devices depend on the ad-hoc mode of their wireless net‐
work interface cards to communicate with each other. If the nodes are within the transmis‐
sion range of the wireless signal, they can send messages to each other directly. Otherwise,
the nodes in between will forward the messages for them. Thus, each node is both an end
system and a router simultaneously.
This effort started as an answer to the numerous questions the authors have
repeatedly had to answer about electrostatic discharge (ESD) protection and
input/output (1/0) designs. In the past no comprehensive book existed suffi-
ciently covering these areas, and these topics were rarely taught in engineering
schools. Thus first-time I/O and ESD protection designers have had consider-
able trouble getting started. This book is in part an answer to such needs.
Failure analysis is invaluable in the learning process of electrostatic discharge (ESD) and
electrical overstress (EOS) protection design and development [1–8]. In the failure analysis
of EOS, ESD, and latchup events, there are a number of unique failure analysis processes
andinformationthatcanprovidesignificantunderstandingandillumination[4].Today,thereis
still no design methodology or computer-aided design (CAD) tool which will predict EOS,
ESDprotectionlevels,andlatchupinasemiconductorchip;thisisoneofthesignificantreasons
why failure analysis is critical to the ESD design discipline.
The goal of this book is to introduce the simulation methods necessary to describe
the behaviour of semiconductor devices during an electrostatic discharge (ESD).
The challenge of this task is the correct description of semiconductor devices under
very high current density and high temperature transients. As it stands, the book
can be no more than a snapshot and a summary of the research in this field
during the past few years. The authors hope that the book will provide the basis
for further development of simulation methods at this current frontier of device
physics.
It has been said that the move from narrowband to broadband access is the second
revolution for the Internet — ‘broadband is more bandwidth than you can use’.
Once users have experienced broadband access there is no turning back. A whole
new world of applications and services becomes possible. No longer is it the ‘world-
wide wait’. The speed of response and visual quality enabled by broadband finally
allows the Internet to reach its true potential.
In the present era, low observability is one of the critical requirements in aerospace
sector, especially related to defense. The stealth technology essentially relates to
shaping and usage of radar absorbing materials (RAM) or radar absorbing struc-
tures (RAS). The performance of such radar cross section (RCS) reduction tech-
niques is limited by the bandwidth constraints, payload requirements, and other
structural issues. Moreover, with advancement of materials science, the structure
geometry no longer remains key decisive factor toward stealth.
