Frequency division multiple access (FDMA) is the first-generation analog mobile access method; FDMA uses separate freauencies for each call. For example if there are four stations, each will receive their own frequency. Thus there is no interference between them. This reduces interference, but limits the number of users. Time division multiple access (TDMA) allocates unique time slots to each user within each channel, thus allowing many users to access the radio frequency without anyone’s interference. Each mobile conversation uses only a particular frequency slot of the time. Code division multiple access (CDMA) was commercially introduced in 1995 by Qualcomm, CDMA quickly became one of the world’s fastest-growing wireless technologies. 3G CDMA networks provide more capacity for voice traffic, along with high-speed data capabilities, hence many cellular service providers are now building or upgrading to it. CDMA is used in both 2G and 3G wireless technologies. Global system for mobile communications (GSM) was developed on TDMA protocol in
Wireless technology platforms: GPRS, EDGE and WAP
GPRS, short for General Packet Radio Services, is an enhancement to GSM technology that integrates GSM and IP technology. GPRS offers always-on, high speed connectivity to the Net. Thus you can check your email on the move and surf the Web at high speeds. In this hi-tech age, people on the move need any-time access to the Net. This is where WAP comes in. It provides Internet access to cell phones. It is an open standard for wireless protocols that is independent of the service providers. To display Web content, the cell phone must have a WAP browser. Nowadays, cell phones often come with GPRS and WAP technology. WAP and GPRS also allow you to download games, send mail and even transfer your messages to your PC. The new EDGE ((Enhanced Data GSM Environment) interface has been developed specifically to meet the bandwidth needs of 3G. Promoted by Ericsson, it offers high-speed data transfers over GSM networks with just a software upgrade to the handset. EDGE allows speeds up to 384 kbps.
