**Preface**

It is the Information era where communication is playing the imperative role in human race's existence. Digital communications, together with its applications and growing technologies, is among today's most active areas of development. The very rapid pace of improvements in technology is the key enabler of the aggressively escalating capacity demands of emerging digital communication systems. With the parental support from Digital Communication two other modes of communication are currently hyped everywhere, Wireless Communication and Mobile Communication. Consequently, there has been a tremendous and very widespread effort on the part of the research community to develop novel techniques that can fulfill this promise. The published literature in this area has grown explosively in recent years, and it has become quite difficult to synthesize the many developments described in the literature. This book is a compilation of the ideas of renowned academicians, researchers and practitioners in the selected field. The chapters are se1f contained and written principally for designers, researchers, and graduate students with some prior exposure to digital communication systems. The purpose of this book is to present, in one place and in a unified framework, a number of key recent contributions in this field. Even though these contributions come primarily from the research community, the focus of this presentation is on the development, analysis, and understanding of explicit algorithms.

Basic principles of data transmission and networking protocols, for example routing are addressed to some extent. There are a few chapters on digital communication techniques, methods and mode of propagation of the digital signals. WiMax, another all-in-one technological concept to serve your day-to-day demands all put together, actually, stands for Worldwide Interoperability for Microwave Access. As widely known WiMax enables the delivery of last mile wireless broadband access as an alternative to ADSL and Cable broadband. The care architecture of WiMax and the structure of its physical layer are also presented to enable the readers to expose on the recent development.

> C. **Palanisamy, Professor and Head** Department of Information Technology, Bannari Amman Institute of Technology, Sathyamangalam, Tamilnadu, India
