2.3.3 Third Generation 3G:
The
main development in the mobile networks has been the development from 2G to 3G
and beyond. This has been primarily driven by the lack of frequency resources
in 2G to cope with the rapid development and penetration of mobile services and
the need for new mobile services with varying demand on bandwidth.
The
3G platforms on the one hand include new frequency bands for the provision of
mobile services, and on the other hand deploy more efficient technologies than
2G, resulting in increased spectral efficiency. Furthermore, the 3G
technologies have been developed due to their potentials in meeting universal
access goal.
This
has been one of the arguments at ITU for backing the development of 3G
standards. In order to generate a more efficient usage of available frequency,
IMT-2000 had the job of standardizing the new air interface that would enable
this.
The
WCDMA air interface was selected for paired frequency bands (FDD operation) and
TDCDMA (TDD operation) for unpaired spectrum. CDMA2000 standard was created to
support IS-95 evolution.
2.3.3.1 Wideband Code Division Multiple Access (W-CDMA)
W-CDMA is the access scheme defined by the ITU to be the main technical
platform for UMTS or 3rd Generation Mobile services. W-CDMA services
are to operate within the following frequency bands: 1920 MHz -1980 MHz and
2110 MHz - 2170 MHz. NTT DoCoMo’s FOMA network uses a version of the W-CDMA
standard in its network deployment.
The
ITU had selected W-CDMA as one of the global telecom systems for the new
IMT-2000 3G mobile communications standard.
In
W-CDMA interface different users can simultaneously transmit at different data
rates and data rates can even vary in time. W-CDMA is capable of delivering up
to 384 kbps in outdoor environments and up to 2 Mbps in fixed indoor
environments.
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