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Although it has history of more than a century, wireless transmission has found widespread use in communication systems only in the last 15–20 years. Currently the field of wireless communications is one of the fastest growing segments of the telecommunications industry. Wireless communication systems, such as cellular, cordless and satellite phones as well as wireless local area networks (WLANs) have found widespread use and have become an essential tool in many people’s every-day life, both professional and personal. To gain insight into the wireless market momentum, it is sufficient to mention that it is expected that the number of worldwide. | 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 1 Introduction to Wireless Networks Although it has history of more than a century wireless transmission has found widespread use in communication systems only in the last 15-20 years. Currently the field of wireless communications is one of the fastest growing segments of the telecommunications industry. Wireless communication systems such as cellular cordless and satellite phones as well as wireless local area networks WLANs have found widespread use and have become an essential tool in many people s every-day life both professional and personal. To gain insight into the wireless market momentum it is sufficient to mention that it is expected that the number of worldwide wireless subscribers in the years to come will be well over the number of wireline subscribers. This popularity of wireless communication systems is due to its advantages compared to wireline systems. The most important of these advantages are mobility and cost savings. Mobile networks are by definition wireless however as we will see later the opposite is not always true. Mobility lifts the requirement for a fixed point of connection to the network and enables users to physically move while using their appliance with obvious advantages for the user. Consider for example the case of a cellular telephone user he or she is able to move almost everywhere while maintaining the potential to communicate with all his her colleagues friends and family. From the point of view of these people mobility is also highly beneficial the mobile user can be contacted by dialing the very same number irrespective of the user s physical location he or she could be either walking down the same street as the caller or be thousands of miles away. The same advantage also holds for other wireless systems. Cordless phone users are able to move inside their homes without having to
