Wireless communication systems, since their inception in the form of cellular communications, have spread rapidly throughout the western world and the trend is catching on in the developing countries as well. These systems have caused revolutionary changes in the way we live. Cellular Commu­ nications have become important both as means of communication and as a new domain ofcommercial enterprise. Hand held telephones are now rapidly replacing the fixed telephone and in less than twenty years, the number of subscribers has reached nearly three quarters of a billion. In a short span of twenty years, the cellular communications progressed from the first generation to the third generation systems, which started operations in Japan on October 1,2001. The first generation wireless technology, which was thought to be obsolete is now being used for fixed wired telephony in several countries of Asia, Africa and Latin America. As some commentator said in 1983, the cellular system is the best thing that has happened in telecommunications since the introduction ofcomputers to the masses. This book is written to provide readers with the fundamental concepts ofwireless communications. It is intended for a graduate course on wireless communications but it could be easily adopted at the senior level by skipping material involving difficult mathematical manipulations. The text does not go through the rigorous material on mathematical treatment of electromagnetic waves and propagation, rather it emphasizes more on the practical aspects of this.