The UMTS standard or the Universal Mobile Telephone Systems is the 3rd of the cellular system generations. The development of the 3rd standard is strongly linked to the main second-generation standards and the network that is now in use around the world like GSM, D-AMPS, CDMA one and PDC. The UMTS is evolved from the current GSM global system for mobiles. with the advent of 3G and the higher bandwidth radio interface of UTRA (universal terrestrial radio access) came the possibilities for arranging of new services and facilities which were not present in the existing 2G systems and also the 2.5G system and networks.
Universal Mobile Telecommunications System (UMTS) is the European standard for 3G mobile communication systems which provide an enhanced range of multimedia services. It has evolved from its basic format through developments such as HSDPA (High-Speed Downlink Packet Access) and HSUPA (High-Speed Uplink Packet Access) to provide very high bandwidth capabilities to support the next generation of telecommunication services.
UMTS supports up to 1920 kbit/s data transfer rates (and not 2 Mbit/s as frequently seen), although at the moment users in the real networks can expect performance up to 384 kbit/s – in Japan upgrades to 3 Mbit/s are in preparation. However, this is still much greater than the 14.4 kbit/s of a single GSM error-corrected circuit switched data channel or multiple 14.4 kbit/s channels in HSCSD, and in competition to other network technologies such as CDMA-2000, WLAN offers access to the World Wide Web and other data services on mobile devices.
WCDMA vs UMTS
Like other real-world W-CDMA implementations, UMTS uses a pair of 5 MHz channels (one for downlink and other for uplink) in case FDD network and only 5 Mhz in TDD network, one in the 1900 MHz range for uplink and one in the 2100 MHz range for downlink. In contrast, the competing CDMA2000 system uses one or more arbitrary 1.25 MHz channels for each direction of communication.
UMTS and other W-CDMA systems are widely criticized for their large spectrum usage, which has delayed deployment in countries that have not allocated new frequencies specifically for UMTS (such as the United States). The specific frequency bands originally defined by the UMTS standard are 1885-2025 MHz for uplink and 2110-2200 MHz for downlink.