Migration Path from 2G to 2.5G to 3G

The specific migration path from any of the 2G platforms that an operator
has deployed in a network to the 3G system involves the establishment of
a migration path. The migration path involves numerous issues and technical
challenges that will fundamentally define the character and services
of the wireless system.
The end goal for the operator to be able to properly implement a 3G solution
that follows the IMT-2000 specification involves the obvious and
painful decision as to which IMT-2000 specification to utilize. For instance,
the IMT-2000 specification that defines the 3G wireless mobility system has
several platforms from which the existing wireless operator must make a
decision as to which to utilize. In a situation when the overseeing regulatory
agency dictates the IMT-2000 platform to utilize, the decision is academic.
However, the difficulty begins when the decision is left to the operator
to make. The difficulty lies in the amount of capital infrastructure that
needs to be deployed for any of these systems in order to take them from a
concept into a physical reality.
A decision from, say, a IS-95B CDMA may be to migrate to a WCDMA
system, but the path from IS-95B to a WCDMA platform does not involve
the commonality of the radio base station equipment, as it would in a
CDMA2000 platform. Alternatively, if a GSM operator chose a CDMA2000
platform, a separate network, as in the previous example, would need to be
deployed in order to provide the radio transport system needed. However,
the operators using IS-136 need to make a fundamental decision as to
which IMTS-2000 platform to utilize, WCDMA or CDMA2000. Either case
requires the deployment of new radio base stations in order to realize the
transition.
Lastly, and very important, to the overall discussion of migration path
decisions is the spectrum that is available to the operator itself. The spectrum
includes not only the bandwidth, but also the fundamental frequency of operation. The radio spectrum in the United States is not the same as
that used in Europe or Asia. Therefore, in the decision and migration strategy
from a 2G to a 3G platform, the operator needs to factor in the interoperability
considerations usually available with existing tri-band mobile
phones.
But no matter which 3G technology is chosen, the operator is left with
two fundamental choices. The first is to continue utilizing the existing technology
platforms,wait until the availability of a 3G platform, and transition
directly from 2G to 3G. The other choice is to choose an interim platform
that hopefully will be compatible with the 3G platform chosen and allow for
enhanced data services to be deployed in advance of 3G, thus trying to capture
the market share.