GSM: 2G Europian standard and the first digital mobile system. It offers only circuit-switched traffic (i.e voice calls, SMS…etc) and data transfer at very low bitrates 9.6kbps.
GPRS: also reffered to as phase 2+. It offered packet-switched traffic with new network components integrated over the existant GSM core network. This allowed data bitrates to increase to 171kbps.
EDGE: It was made to cover the delay of delivery of 3G/UMTS network. It supported data rates upto 384kbps
UMTS: the first 3G Europian standard network. It is the optimal solution for GSM operators to support 3G services.
UMTS-WCDMA:The Air interface technique used for this network is WCDMA. This technique allowed data rates to reach 2Mbps.
UMTS-HSDPA: It is actually a software upgrade to the UMTS network using the same air interface technique used in UMTS (WCDMA).
WCDMA : Wideband Code Division Multiple Access
HSDPA : High Speed Downlink Packet Access(aka High-Speed Data Packet Access)
WCDMA : 384kbps
HSDPA : >384kbps,3.6Mbps,7.2Mbps
WCDMA referred as 3G
HSDPA referred as 3.5G
Features in HSDPA that make these things possible are Fast Packet Scheduling and AMC (Adaptive Modulation and Coding). Fast Packet Scheduling allows the base station to adjust the amount of data that is being transmitted to a certain device based on the current conditions. AMC also allows the base station to select a better modulation and coding scheme if the signal quality allows it. Initially, users are assigned with QPSK, but can be changed to a lot of other coding schemes that provide better data rates if the signal between the device and the base station is strong enough.