An Overview of Wireless Networks

摘要

In choosing between wire and wireless networks; convenience, cost, performance and security issueshave to be taken into consideration. The birth of wireless communication was when the firstoperational cellular communication system was introduced and deployed in Norway in 1981. This wasfollowed by similar systems in the US and the UK. The first generation (1G) systems provided voicetransmissions using only analog modulation frequency around 900 MHz. Second generation (2G) is theGlobal System for Mobile Communications (GSM) and was introduced in 1991 in Europe. At the endof 1997, GSM service was available in more than 100 countries, especially in Europe and Asia. GSMprovides voice and limited data services and uses digital modulation with improved audio quality. The2.5G systems were introduced in 2000 and enhance the data capacity of GSM and mitigate some of itslimitations. The third generation (3G) cellular service is the Universal Mobile TelecommunicationsSystem (UMTS) also introduced in 2000. The third generation (3G) sustains higher data rates and hasopened the door to internet based applications. The challenge of today’s wireless systems is to achievethe goals of true broadband cellular service referred to as the fourth generation (4G). This 4G isintended to provide high speed, high capacity, low cost per bit, and IP based services which arenecessary to accommodate growing traffic in 2010 and thereafter. In this paper, we present a broadoverview of the evolution of wireless systems, examine the limitations of the above mentionedgenerations of wireless systems, and look at its present and future challenges and applications.