Monday, November 10, 2008

The UMTS technology

Combine UMTS W-CDMA, TD-CDMA, TD-SCDMA interfaces, GSM's Mobile Application Part (MAP) core, GSM and the family of speech codecs. In the most popular mobile cellular variant of UMTS, W-CDMA is currently used. It is worth noting that other wireless standards use W-CDMA as their interface air, including FOMA.

On UMTS W-CDMA uses a pair of 5 MHz channels. However, competition CDMA2000 system uses one or more arbitrary 1.25 MHz in each direction of communication. UMTS and other W-CDMA systems are widely criticized for their broad spectrum of use, which delayed the deployment in the country which has acted relatively slowly in the allocation of new frequencies in particular for 3G services (such as the United States, Unis).

The bands originally defined by the UMTS standard are 1885-2025 MHz for mobile-to-basic (uplink) and 2110-2200 MHz for the core mobile (downlink). In the USA, 1710-1755 MHz and 2110-2155 MHz will be used instead, as the 1900 MHz band has already been used. [1] Although UMTS2100 is the most widely deployed UMTS band, some countries UMTS operators use the 850 MHz and / or 1900 MHz (independently, which means uplink and downlink are in the same band), including the United States United by AT & T Mobility, and in Australia by Telstra (850 MHz).

For GSM operators, it is simple but costly migration to UMTS: a large part of the infrastructure is shared with GSM, but the cost of obtaining new spectrum licenses and UMTS above towers existing is high.

A major difference of UMTS compared to GSM is the interface doing radio GSM / EDGE Radio Access Network (Geran). It can be connected to various commodities such as the Internet, ISDN, GSM or UMTS network. Geran includes three lower layers of the OSI model. The network layer (OSI 3) protocols form the protocol Radio resource management (RRM). They manage the bearer channels between mobile terminals and fixed network including transfers.

Edited and Rewritten from Source: http://en.wikipedia.org

 
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