UMTS is an umbrella term for the third
generation radio technologies developed within 3GPP.
The
radio access specifications provide for Frequency Division Duplex (FDD) and
Time Division Duplex (TDD) variants, and several chip rates are provided for in
the TDD option, allowing UTRA technology to operate in a wide range of bands
and co-exist with other radio access technologies.
UMTS
includes the original W-CDMA scheme using paired or unpaired 5 MHz wide
channels in globally agreed bandwidth around 2 GHz, though subsequently,
further bandwidth has been allocated by the ITU on a regional basis.
W-CDMA
was specified in Release 99 and Release 4 of the specifications. High Speed
Packet Access (HSPA) was introduced in Releases 5 (Downlink) and 6 (Uplink)
giving substantially greater bit rates and improving packet-switched
applications.
UMTS
is not just about radio: the radio access network connects to the core network
which is an evolution from the GSM core. 3GPP has expanded its capabilities, in
principle allowing most services to be delivered over either 2G GERAN
(GSM/EDGE) or 3G UTRAN.
The
core network is becoming progressively access-agnostic, allowing home base stations
serving pica-cells to connect directly to the core network via subscribers’
ASDL lines.
3GPP
is now working on Long Term Evolution (LTE), which will build on UMTS, as the
Industry looks beyond 3G.
Just
as GSM has become synonymous with the whole mobile system for 2G, UMTS is 3G,
which includes the whole of the W-CDMA and HSPA specifications catalogue.
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