This book is an excellent reference for those working in the broad
fields of communication theory, information theory, and modem design. It
is essential for researchers in modulation and coding for voiceband
telephone line modems; signal constellation design; nonlinear precoding
for modems; and trellis coding.
The author presents the theory behind the new modulation and coding
techniques included in ITU-T Recommendation V.34. Topics discussed
include signal constellation shaping by shell mapping, nonlinear
precoding, four-dimensional trellis codes, and fast equalizer training
by using periodic sequences and FFT methods. In addition, several
approaches that were considered but not accepted are presented including
trellis shaping, trellis precoding, and modulus conversion. The book is
essentially a history of the standard for a state-of-the-art voiceband
telephone channel modem. Many of these techniques were invented during
the committee deliberations. The rapid advances in digital signal
processor technology allowed the committee to consider approaches that
were significantly more complex and effective than anything implemented
previously.
The first chapter presents the basics of lattices and is the foundation
for multi-point constellation design. The second chapter discusses the
theoretical properties of large constellations including shaping gain,
constellation expansion ratio, and peak-to-average ratio. Chapter 3
presents the elements of convolutional and trellis codes for reference
purposes. A technique for constellation shaping called trellis shaping
is presented in Chapter 4. Chapter 5 examines methods for nonlinear
channel precoding. Chapter 6 discusses the combination of the trellis
precoding and nonlinear precoding methods of Chapters 4 and 5 into a
technique called trellis precoding. Another method of assigning data
bits to constellation point called modulus conversion is discussed in
Chapter 7. The shell mapping method of constellation shaping is
presented in Chapter 8. The four-dimensional constellation used by V.34
modems is discussed in Chapter 9. The combination of shell mapping,
precoding, and trellis coding arranged in a feedback loop that was
selected for Recommendation V.34 is the topic of Chapter 10. Finally,
Chapter 10 presents the theory of a special type of periodic sequence
called a CAZAC sequence and shows how an adaptive equalizer can be
rapidly trained using these periodic sequences and FFT methods.
Much of the material has never been published in a book before, but
exists only in journal articles and ITU-T working papers. These topics
include trellis shaping, LTF precoding, trellis precoding, modulus
conversion, shell mapping, the V.34 four-dimensional constellation, the
combination of shell mapping, precoding and trellis coding in a feedback
arrangement, and CAZAC sequences.
The book will interest any professional involved with modem design. It
is also suitable as a text for an advanced course in modulation and
coding at the graduate level.
