1G, 2G, 3G and 4G are the wireless communication standards. 1G is based on analog communications which offers 2.4 kbps. It was based on a technique known as FDMA ( Frequency division multiple access). 2G which is a digital communications standard and is based on GSM offers 64 kbps.it is based on the combination of TDMA ( Time division multiple access) and FDMA (Frequency division multiple access).CDMA ( Code division multiple access) also comes under 2G. 3G is based on the WCDMA concept and it offers increased data rates of 144 kbps - 2 mbps. 4G is based on LTE technology and it offers data rates of 100 mbps - 1 gbps. LTE-A and LTE pro are the enhancements to LTE technology.