Better known among some mobile phone operators as HSDPA or HSUPA, it allows existing 3G (UTMS) operators to upgrade their networks so that theoretical download speeds of up to 14.4Mbps (5.76Mbps upload) may be possible over them (Mobile Broadband).

By comparison the enhanced version of HSPA, HSPA+ (HSPA Plus), offers data rates of 'up to' 42Mbps (22Mbps upstream). Both are likely to be replaced by Long-Term Evolution (LTE) and or mobile WiMAX in the future (4G).

Full Details:

http://www.ispreview.co.uk/broadband_mobile.php