UMTS transmission rate

The transmission speed of UMTS is one of its main advantages over all other mobile communications systems.

Assuming a typical transmission speed of 9.6 kbit/s for GSM, High Speed Circuit Switched Data( HSCSD) theoretically achieves 115.2 kbit/s, although in practice this is assumed to be 57.6 kbit/s or 38.4 kbit/s; for General Packet Radio Service( GPRS), the theoretical value is 171.2 kbit/s, which is likely to be reduced to 58 kbit/s in practice; and for UMTS, the theoretical value is 2 Mbit/s or a chip rate of 3.84 MChips/s.

This value is available to all active subscribers in a radio cell together in a 5 MHz channel. Because the bandwidth is shared among the active subscribers, the 2 Mbit/s is only achieved if there is no more than one active UMTS user in a radio cell. If there are two active users, the bandwidth shrinks to 384 kbit/s. If five users are active in a cell, they each have 144 kbit/s, and if nine users are active, the bandwidth is even reduced to 64 kbit/s.

The figures mentioned refer to data transmission and not to telephony.