Last two decades have seen two major transformations in the syllabus of Digital Communication at the undergraduate level. Techniques like QAM, MSK, OQPSK, etc. entered the realm of classroom discussions from technical journals. This was the first transformation that happened in the mid-nineties in the Indian universities and engineering institutions. The second transformation came mainly during the last five years with the onset of telecom revolution, particularly the mobile telephone’s penetration to commoners. Every serious electronics student started relating the abstract digital communication techniques, hitherto known only in classrooms, to the making of the tiny phone in his or her pocket. This rejuvenated the interest in the so-called ’stochastic” (i.e. arbitrary!) subject of ‘Digital Communication’. Hence, this was the appropriate time for teachers to bring in the advanced concepts of geometrical representation of signals and underscoring the unity and diversity of various modern modulation techniques. A new textbook of ‘Digital Communication’ addressing these emerging pedagogical issues was in order and this book is aimed at being just that. The underpinning in this text is the optimisation between the bandwidth efficiency and power efficiency of a communication system, without losing the goal of its applicability to the ongoing telecom revolution.

The emphasis in this book is on clarifying the concept from the basics, not on the implementation of a functional block. It is my belief that implementation of a particular functional block should be emphasised in circuit courses, particularly the courses on RF design. Also, due to the modern state-of-the-art technology, most of the implementation issues are becoming trivial with the advent of generalised implementation block in hardware as well as firmware and software (software radio!).

The book consists of three parts. The first part, Introduction to Digital Communication, comprising two chapters is introductory in nature and covers all the necessary tools for analysis of digital communication systems. Chapter 1 provides the history of development and a brief overview of the digital communication system to the readers. Chapter 2 introduces some key concepts like geometrical analysis of signal, digital signal’s bandwidth, communication channel models and some key concepts from statistical theory to represent non-deterministic signals and noise. Throughout the book these concepts are used and to facilitate referencing these key concepts are clubbed together in this chapter.

The second part, Baseband Systems, is exposition of various techniques and subsystems used in a typical baseband system. This part comprises three chapters. Chapter 3 introduces the reader to the techniques of formatting the source signal. Chapter 4 introduces further processing required at the transmitter before sending the signal to the receiver. The last chapter of this part, viz. Chapter 5 deals with the reception of the baseband signal.

The last part of the book has two chapters and deals with Modulated Systems. Chapter 6 deals with the transmission of digitally modulated signals whereas the last chapter, viz. Chapter 7 deals with the reception of such signals.

Last decade witnessed a change in the Communication Engineering curriculum over different semesters. Almost all engineering colleges now have a course on “Signals and Systems”. Further “Analog Communication” is the precursor to “Digital Communication” in most of the colleges. Also, many modern curricula are offering a course on “Mobile Communication” as a sequel to the “Digital Communication” course. In this scenario, it becomes imperative that a “Digital Communication” textbook emphasises on its continuity to mobile communication(particularly the 2G mobile system), even if that amounts to sacrificing some material from Analog Communication to which the students already have an exposure. This is the reason the topics on determinisitic communication, signals and systems and analog pulse modulation techniques have not been included in this book. However, great care has been taken to maintain the continuity from analog communication and a careful reader would be able to trace the unity of principles between the two.

Considerable effort has been made to detail the mathematical derivations in the text without which, it is my belief, communication concepts are not fully grasped. Particularly for undergraduates, if mathematical emphasis is discounted in favour of popular presentation, the foundation remains weak and students might face problems at the postgraduate level. With my presentation, I strive to attract students interest in the mathematical treatment of the subject. Nowadays most electronics teachers are facing a dilemma in their classroom presentations due to the curricular changes taken place in the recent past. All suggestions from the readers for improving this aspect of the book for the future editions are welcome.

Ancillary material available with this book includes Solution Manual and PowerPoint Slides for the teachers, and Self Test Quiz for students.

AMITABHA BHATTACHARYA