Preface
Ten years have passed since our first-of-its-kind book on optical code-division multi-
ple access (CDMA), Prime Codes with Applications to CDMA Optical and Wireless
Networks,publishedbyArtechHousein2002.Thebookcoveredopticalcoding the-
ory, performance analytical techniques, and proof-of-principle experiments for the
specialized field of optical CDMA, from the mid-1980s to early2002.Itnotonly
provided the first comprehensive text, but also facilitated research and education in
this emerging field. Since the early 1990s, numerous developments in optical CDMA
have been contributed by worldwide researchers. Some of the major works were col-
lected in the book, Optical Code Division Multiple Access: Funda me ntals and Appli-
cations,editedbyP.R.PrucnalandpublishedbyTaylor&Francisin2006. The book
covered the whole spectrum of the field of optical CDMA, including its history and
developments, physical hardware technologies, modern experimental testbeds, and
potential applications. Being considered renowned expertsinopticalcodingtheory,
we contribu ted one chapter, “Optical CDMA Codes,” in the book.
Similar to its wireless counterpart, optical CDMA can be classified into two main
research categories: hardware technology and coding technique. Nevertheless, opti-
cal CDMA is unable to receive benefits from existing wireless-CDMA technologies
or coding techniques because optical fiber is generally not good at preserving phase
information. Optical CDMA also encounters different operating environments and
issues, thus requiring unconventional coding as well as transmission techniques and
technologies. A new field, optical coding theory, has emergedandbeendeveloped
for the design and analysis of families of optical codes for a variety of optical-CDMA
applications. Furthermore, optical CDMA currently followsasimilarhistoricalpath
of wireless CDMA in the sense that the advances in hardware technologies must
be supported in tandem with contemporary coding techniques.Althoughthereare
books on the coding theory of wireless communications, thereisnobookspecifi-
cally dedicated to the subject matter of op tical cod ing theory.
Since the mid-1980s, optical codes have been primarily designed for providing
multiple and simultaneous access in CDMA-based optical communication systems
and networks, such as local area networks. In add ition, o ptical coding is now re-
ceiving attention in environments requ iring address or useridentificationbymeans
of optical codes, such as optical wireless, optical switchednetworks,passiveoptical
networks, fiber-sensor systems, data-obscurity transmission, IP routing, and fault tol-
erance, monitoring, and identification in optical systems and networks. Nowadays,
optical coding theory, which is not limited to optical-CDMA applications anymore,
includes construction of optical codes for various optical applications, improvements
in performance analytical techniques of optical codes, and development of novel op-
tical coding techniques supported by the latest hardware technologies.
Optical coding theory and its app lications to coding- based optical systems and
networks have been studied for the past three decades. Until the mid-1990s, optical
xxi
xxii Preface
codes were based on one-dimensional (1-D) coding in time or wavelength. T o pro-
vide sufficient performance, very long 1-D optical codes wereneeded,thusrequiring
ultrashort optical pulses and rendering such systems impractical. We were among
the leaders in directing research momentum to two-dimensional (2-D) coding in time
and wavelength simultaneou sly. Since then, research in the area of 2-D coding tech-
niques has flourished. Our series of work on the theoretical and application aspects of
various families of prime codes played a major role in such developments. Our con-
tributions established the foundation of algebraic 1-D and 2-D optical coding, which
made high-rate, high-capacity, coding-based optical systems and networks feasible.
In the late 1990s, research on quality-of-service (QoS) control and services prioriti-
zation in multirate, multimedia codin g - based optical systems by means of specially
designed optical codes began attracting attention. The impact is prominent as future
systems are expected to support services with different rates, QoSs, an d pr io r ities.
Our work on optical coding theory has been scattered over numerous ar ch ival
journals. To collect these important works in one place coherently, we write this first-
of-its-kind monograph to cover the fundamentals and development of optical coding
theory with a focus on various families of prime codes and their potential applica-
tions to coding-based optical systems and networks. Prerequisites include a basic
knowledge of linear algebra and coding theory, as well as a foundation in probability
and com m unications theory. A theorem–pr o of approach is usedsothattheoriesare
broken down into digestible form and readers will be able to understand main mes-
sages without searching through tedious proofs. Examples are used to illustrate the
fundamental concepts and to show how prime codes are constructed an d analyzed.
The performances o f prime codes in a variety of applications are also d etailed. In
addition to targeting researchers in the field, this book alsocoversworkingknowl-
edge of op tical coding theory and pr ime codes for the design ofcoding-basedoptical
systems and networks for engineers. We hope that systems engineers, research and
development professionals, professors, graduate students, and mathematicians who
are interested in optical coding theory and its applicationsfindthisbookusefuland
informative.
The first part of this book sorts out the m athematical conceptsandformulations
that are important in the second part. Chapter 1 covers the preliminary materials
that are necessary to the understanding and application of the essential algebraic
techniques of optical coding theory, such as Galois fields, vectors, matrices, Markov
chains, an d Gaussian and combinatorial analytical tools. Inadditiontoproviding
readers with the necessary mathematical tools, the applications of optical codes in
various coding schemes and the study of supporting hardware technologies are given
in Chapter 2. The second part of this book starts out with the constructions and prop-
erties of various families of 1-D asynchronous prime codes with illustrative exam-
ples and performance analyses in Chapter 3. Chapter 4 investigates 1-D synchronous
prime codes and follows with examples of applications. Chapter 5 studies 2-D asyn-
chronous prime cod es with various coding flexibilities, expan d ed cardinalities, and
variable performances. The concepts of shifted-code keyingandmulticodekeying
for high-rate transmission of multiple bits per symbol are also introduced. Chapter 6
Preface xxiii
discusses 2-D synchronous prime codes, which possess true code orthogonality at
the expense of synchronization. Chapter 7 investigates the use of multilength prime
codes for supporting m u ltiple-rate, multimedia services inopticalsystemsandnet-
works. The uses of code weight and code power to control the QoSofmultime-
dia services are also analyzed. Finally, this book concludeswiththeconstructionof
three-dimensional prime codes in Chapter 8.
We wou ld like to th ank Professors Paul R. Prucnal and Thomas E.Fuja,ourPh.D.
advisors and long- time friends, f o r their pro f essional g u idance, inspiration, and assis-
tance all these years. We are also grateful to Dr. Cheng-Yuan Chang of the National
United University, Taiwan, for p roofreading this book , and his past, present, and fu-
ture involvement and contributions to our endeavor in the advancement of optical
coding theo r y and optical CDMA. We are thankful to the U.S. Defense Advanced
Research Projects Agency, the National Science Council of Republic of China, Hof-
stra University, and National Chung Hsing University for their gener ous sup p ort. We
thank the IEEE for publishing our findings in its journals and Artech House for grant-
ing us permission to use materials from our previous book. Finally, we would like
to pay tribute to numerous pioneers and contributors in the field of optical CDMA.
Without their dedication and collective contributions, thefieldwouldnothaveflour-
ished and reached today’s status. To our best knowledge, their published, archival
articles and boo ks are cited according ly in the bibliographies of this book, wherever
suitable. To name a few, C. A. Brackett, F. R. K. Chung, P. A. Davies, G. J. Foschini,
J. P. Heritage, J. Y. N. Hui, P. V. Kumar, P. R. Prucnal, J. A. Salehi, M. A. Santoro,
A. A. Shaar, V. K. Wei, G. Vannucci, and, last but not least, A. M. Weiner are some
of the early pioneers in the field of optical CDMA with archivaljournalarticlesbeing
published before 1990. We tried our best to be inclusive in thecitations.Ifanyrel-
evant literature or personnel is found omitted, please contact us an d we will amend
this accordingly in a future edition.
Wing C. Kwong
Princeton Junction, New Jersey
Guu-Chang Yang
Taichung, Taiwan
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