When thinking about mobile radio engineers there is a tendency to
assume that the engineering function relates solely to the technical
aspects of the network, such as the equipment design or the network
design. That is certainly a key part of the role of a mobile radio engineer.
However,increasinglyengineersarerequiredtointeractwithprofession-
als from other divisions.
WIRELESS communication has become increasingly important not only for professional appli-
cations but also for many fields in our daily routine and in consumer electronics. In 1990,
a mobile telephone was still quite expensive, whereas today most teenagers have one, and
they use it not only for calls but also for data transmission. More and more computers use
WIRELESS local area networks (WLANs), and audio and television broadcasting has become
digital.
WIRELESS communications has become a field of enormous scientific and economic interest. Recent
success stories include 2G and 3G cellular voice and data services (e.g., GSM and UMTS), WIRELESS
local area networks (WiFi/IEEE 802.11x), WIRELESS broadband access (WiMAX/IEEE 802.16x), and
digital broadcast systems (DVB, DAB, DRM). On the physical layer side, traditional designs typically
assume that the radio channel remains constant for the duration of a data block. However, researchers
and system designers are increasingly shifting their attention to channels that may vary within a block.
In addition to time dispersion caused by multipath propagation, these rapidly time-varying channels
feature frequency dispersion resulting from the Doppler effect. They are, thus, often referred to as
being “doubly dispersive.”
T
his book covers basic communications theory and practical imple-
mentation of transmitters and receivers. In so doing, I focus on dig-
ital modulation, demodulation methods, probabilities, detection of
digital signals, and spread spectrum system design and analysis. This book
was written for those who want a good understanding of the basic prin-
ciples of digital WIRELESS communication systems, including spread spec-
trum techniques. This book also provides a good intuitive and practical
approach to digital communications. Therefore it is a valuable resource for
anyoneinvolvedinWIRELESScommunicationsandtransceiverdesignfordig-
ital communications. The reader will gain a broad understanding of basic
communication principles for transceiver design, digital communications,
and spread spectrum, along with examples of many types of commercial
and military data link systems.
Fourth Generation (4G) WIRELESS communication systems aim to allow peak data
rates in the range of 1 Gbps for nomadic access and 100 Mbps for vehicular mobil-
ity. 4G aims to support current and emergent multimedia services, such as mobile
TV, social networks and gaming, high-definition television and video telecon-
ference, multimedia messaging service, using the All-over IP concept and with
improved quality of service.
Public telephone operators and new independent WIRELESS operators through-
out the world are deploying WIRELESS access in an effort to drastically reduce
delivery costs in the most expensive part of the network?the local loop.
Available radio technology enables both existing and new entrants to access
subscribers in a rapid manner and deliver their basic telephony products and
broadband-enhanced services.
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.
Visible light communications (VLC) is the name given to an optical WIRELESS
communication system that carries information by modulating light in the visible spectrum
(400–700 nm) that is principally used for illumination [1–3]. The communications signal
is encoded on top of the illumination light. Interest in VLC has grown rapidly with the
growth of high power light emitting diodes (LEDs) in the visible spectrum. The
motivation to use the illumination light for communication is to save energy by exploiting
the illumination to carry information and, at the same time, to use technology that is
“green” in comparison to radio frequency (RF) technology, while using the existing
infrastructure of the lighting system.
Two of the major developments reshaping the telecommunications landscape are
mobile WIRELESS connectivity and the migration of voice telephone services to IP
technology. Those two ideas come together in networks that carry voice services
over a WIRELESS LAN (VoWLAN). The purpose of this text is to provide network
professionals with the technical background and practical guidance needed to
deploy these networks successfully.
Second-generation telecommunication systems, such as the Global System for Mobile
Communications (GSM), enabled voice traffic to go WIRELESS: the number of mobile phones
exceeds the number of landline phones and the mobile phone penetration is approaching
100% in several markets. The data-handling capabilities of second-generation systems are
limited, however, and third-generation systems are needed to provide the high bit-rate
services that enable high-quality images and video to be transmitted and received, and to
provide access to the Web with higher data rates.
