2G Cellular

With second-generation networks, or 2G, wireless technology progressed from analog to digital. These networks are still the most prevalent standard in use today. There are three main 2G network standards: CDMA (Code Division Multiple Access), GSM (Global System for Mobile Communications), and TDMA (Time Division Multiple Access). Each type has its own characteristics and features. For instance, GSM networks are global, and the mobile devices connecting to them can be used in the United States and abroad.

But 2G networks were primarily intended for digital voice services. Under ideal circumstances, 2G networks are painfully slow at sending data, reaching 10 to 19 kilobits per second, which is much less than half the speed of a traditional 56-kbps dial-up modem. And unless they've been especially optimized, most Web pages accessed from a 2G network inch across a handheld screen, which makes surfing the Web on a 2G wireless device as efficient as running underwater. To date, network service providers have had a difficult time luring the masses onto the wireless Web

Second Generation:

1. Global System for Mobile Communications (GSM) was the first commercially operated digital cellular system. It was first developed in the 1980s through a pan-European initiative, involving the Eureopean Commission, telecommunications operators and equipment manufacturers. The European Telecommunications Standards Institute was responsible for GSM standardization. GSM uses TDMA (Time Division Multiple Access) technology. It is being used by all European countries, and has been adopeted in other continents. It is the dominant cellular standard today, with over (45%) of the world's subscribers at April 1999.
TDMA IS-136 is the digital enhancement of the analog AMPS technology. It was called D-AMPS when it was fist introduced in late 1991 and its main objective was to protect the substantial investment that service providers had bmade in AMPS technology. Digital AMPS sevices have been launched in some 70 countries worldwide (by March 1999, there were almost 22 million TDMA handsets in circulation, the dominant markets being the Americas, and parts of Asia)
2. CDMA IS-95 increases capacity by using the entire radio band with each using a unique code (CDMA or Code Division Multiple Access) . It is a family of digital communication techniques and South Korea is the largest single CDMA IS-95 market in the world.
Personal Digital Cellular (PDC) is the second largest digital mobile standard although it is exclusively used in Japan where it was introduced in 1994. Like GSM, it is based on the TDMA access technology. In November 2001, there were some 66.39 million PDC users in Japan.
3. Personal Handyphone System (PHS) is a digital system used in Japan, first launched in 1995 as a cheaper alternative to cellular systems. It is somewhere in between a cellular and a cordless technology. It has inferior coverage area and limited usage in moving vehicles. In November 2001, Japan had 5.68 million PHS subscribers.