ABSTRACT
The convenience of true mobility offered by wireless connectivity is the main factor behind widespread acceptance of wireless technologies. The global system for mobile communication (GSM), a secondgeneration cellular system designed mainly for mobile telephony, currently has more than one billion users worldwide. Systems like GSM or the third-generation universal mobile telecommunication system (UMTS) nevertheless require extensive infrastructure. The commercial and industrial deployment of systems that function on a smaller scale and do not require costly frequency licensing or infrastructure has become more appealing; such systems include wireless personal area networks (WPANs) and wireless local area networks (WLANs).
