Evolution from 2G to 3G

There are several 2G-to-3G evolution scenarios for the operators, and some
would be content with using 2.5G technologies to make their networks reach 3G characteristics and features [2, 5–7]. Figure 2.1 shows the different evolution
scenarios. Although WCDMA, also known as IMT-2000 or UMTS [8],
has emerged as the dominant worldwide standard, other flavors of 3G standards
(e.g., CDMA2000 [3, 9]) are still being considered by some operators
and countries.
As a solution, the GSM operators are moving towards GPRS data rates
of 171 Kbps [2, 8]. TDMA (and some GSM) operators are planning for
EDGE [2, 5]—384 Kbps with full mobility. The IS-95 [5] CDMA operators
are considering single carrier radio transmission technology (1xRTT) [10]
(144-Kbps standard). The 1xRTT is interim step towards CDMA2000.