Wireless Technology

As name suggest wireless means without wire. It is the technology employing the use of any media (particularly air, even vacuum) without wire or without any conductor, for the transmission of signal. Evaluation of wireless technology can also be defined in generation.

1st Generation(1G)- First generation of wireless technology use the analog technology. It uses FDMA(Frequency Division Multiple Access) for modulation.
Ex. AMPS(Advanced Mobile Phone Service) - in U.S.

2nd Generation(2G)- Second generation uses digital technology. Voice is digitized over circuit. It uses TDMA(Time Division Multiple Access) and FDMA technology.
Ex. GSM (Global System for Mobile communication) technology.

2.5th Generation(2.5G)- Generally similar to 2nd generation, it uses digitized data and known as 2.5G. The only difference is that it uses data in the form of packets over digital networks, but voice is digitized over circuit like 2G.
Ex. GPRS(General Packet Radio Service) technology.

3rd Generation(3G)-Third generation uses spread spectrum technology for media access and encoding. In 3G both data and voice use packets.
Ex. CDMA(Code Division Multiple Access) technology.