Wireless networks, as the name suggests, utilize wireless transmission for exchange of information. The exact form of wireless transmission can vary. For example, most people are accustomed to using remote control devices that employ infrared transmission. However, the dominant form of wireless transmission is radio-based transmission. Radio technology is not new, it has a history of over a century and its basic principles remain the same with those in its early stage of development. In order to explain wireless transmission, an explanation of electromagnetic wave propagation must be given. A great deal of theory accompanies the way in which electromagnetic. | Wireless Networks. P. Nicopolitidis M. S. Obaidat G. I. Papadimitriou and A. S. Pomportsis Copyright 2003 John Wiley Sons Ltd. ISBN 0-470-84529-5 2 Wireless Communications Principles and Fundamentals Introduction Wireless networks as the name suggests utilize wireless transmission for exchange of information. The exact form of wireless transmission can vary. For example most people are accustomed to using remote control devices that employ infrared transmission. However the dominant form of wireless transmission is radio-based transmission. Radio technology is not new it has a history of over a century and its basic principles remain the same with those in its early stage of development. In order to explain wireless transmission an explanation of electromagnetic wave propagation must be given. A great deal of theory accompanies the way in which electromagnetic waves propagate. In the early years of radio transmission at the end of the nineteenth century scientists believed that electromagnetic waves needed some short of medium in order to propagate since it seemed very strange to them that waves could propagate through a vacuum. Therefore the notion of the ether was introduced which was thought as an invisible medium that filled the universe. However this idea was later abandoned as experiments indicated that ether does not exist. Some years later in 1905 Albert Einstein developed a theory which explained that electromagnetic waves comprised very small particles which often behaved like waves. These particles were called photons and the theory explained the physics of wave propagation using photons. Einstein s theory stated that the number of photons determines the wave s amplitude whereas the photons energy determines the wave s frequency. Thus the question that arises is what exactly is radiation made of waves or photons. A century after Einstein an answer has yet to be given and both approaches are used. Usually lower frequency radiation is explained using .
