1.1 Introduction

It is hard to escape the current excitement regarding wireless technology. From the executive who reads his or her e-mail in the airport lounge, to the teenager playing with a new mobile phone, you can see it everywhere you look.

Companies are still restructuring their business processes in order to enter the Internet era. But they realize that advances in technology do not come to an end with the Internet. Already many of them are ensuring that their Web content is accessible to the various mobile devices appearing on the market.

And yet, even though wireless communication has received renewed attention recently, it is nothing new. Smoke signals, human speech, and visual gestures are merely some of the many forms of communication that people have used since the beginning of recorded history. And, of course, all of these were very effective without using any wires whatsoever.

Paradoxically, it was the introduction of wires and their use as a medium for communication that enabled the informational infrastructure of the twentieth century. It was this pivotal advance in technology that provided a framework for the new economy to flourish.

Yet when we speak about wireless technology today, we don't usually mean all technology that does not use wires. We are typically referring to a very specific technique of transmitting electromagnetic energy through the atmosphere.

This type of wireless transmission has been in use most of the century. However, its application has been limited to a small subset of all communication,...