Mobile computing is based on cellular networks with higher data rates, such as those offered by UMTS networks or WiMAX networks. Since the UMTS infrastructure is well developed, external UMTS modems can be connected to the mobile devices and Internet access can be realized via them.
The UMTS standard specifies a data rate of 384 kbit/s for mobile applications. The HSPA access technologies High Speed Uplink Packet Access( HSUPA) and High Speed Downlink Packet Access( HSDPA) increase this data rate to 5.76 Mbit/s (HSUPA) and 7.2 Mbit/s (HSDPA, level 3).
For mobile Internet, these technologies are implemented in UMTS sticks or UMTS USB sticks, also known as surf sticks. UMTS sticks can hardly be distinguished from USB sticks; they contain the UMTS receiver andmodem, and have a USB plug that is inserted into the USB port of the notebook, netbook or tablet. The UMTS sticks contain a slot for the USIM card, and information can also be stored on the flash memory of the stick.