UMTS Terrestrial Radio Access (UTRA) is the radio interface of UMTS. The UMTS radio interface has two different modes, an UMTS FDD mode and a UMTS TDD mode.

The UMTS FDD mode makes use of paired bands for the uplink and the downlink. The core frequency band that is available for UMTS FDD is 1920-1980 MHz paired with 2110-2170 MHz. In this paired band the radio interface makes use of Wideband CDMA (W-CDMA). This mode is used to set up a wide area mobile network with bit rates of 144 kbit/s in suburban and rural areas for high mobile users (up to 500 km/h) up to 384 - 512 kbit/s in urband areas with medium mobility (up to 120 km/h).

UMTS TDD has two bands available: 1900-1920 MHz and 2010-2025 MHz. The radio interface of the unpaired bands makes use of Time Duplex CDMA (TD-CDMA and TD-SCDMA). This mode is used for high bit rates at hot spots (up to 2 Mbit/s) with low mobility (less then 10 km/h).

All bit rates are based on the first generation of UMTS. Further evolutions of UMTS will make even higher transmission speeds possible.

See also