Deployment Issues

As implied previously, several deployment issues are associated with the
introduction of CDMA2000-1x into a wireless system. Some of the obvious
issues relate to the current spectrum usage that the operator has license
control of. The spectrum usage considerations take on a different meaning
depending on whether the system is new, that is, not a current infrastructure,
or if it may or may not have the available spectrum from which to
deploy the CDMA2000-1x channels.

Of course, an operator also needs to factor other issues into the decision
process when deploying CDMA2000. Capacity is one of those topics and is
driven by both the current capacity and utilization of the existing radio
spectrum for the system. For example, if the system has the operator contemplating
deploying CDMA2000-1x with IS-95A/B deployed also, then the
decision of whether to convert existing IS-95 channels to that of IS-2000
needs to be made as well as, of course, which carriers are involved. Another
issue that could come about is when an existing operator chooses to change
or augment his or her existing wireless offering by introducing CDMA2000-
1x into a GSM or IS-136 environment.

The coverage of the system with regards to 1x needs to be addressed and
well thought out. The decision based on whether to deploy the 1xRTT channels
in a 1:1 or N:1 scenario needs to be decided upon from the onset of the
design process. Some of the decisions could be centered around a high-speed
packet data offering for the core or heavy commuter locations like an airport
or large industry park. Ultimately, the cost of the deployment will drive
the final decision metric of when, how, and why.

One of the first issues that comes about in the determination of how to
deploy a CDMA2000-1x system, besides estimating demand, is how channel
assignment process are determined. The channel assignment method for
1xRTT can take on a slight variation when the decision is to deploy only 1x,
as opposed to 1x and 3x. The variant is due primarily to the guard band issues that are different for 1x and 3x. The recommended channel assignment
scheme for both cellular and PCS frequency bands is shown in
Tables 5-5 and 5-6 .

The channel chart listed here requires a guard band, and the guard band
for a single CDMA2000-1x, which is the same as IS-95, is shown in Figure
5-10a. Figure 5-10b shows the requirement when implementing a second
channel and the overall impact to the spectrum or rather the existing
channel plan that may exist in a wireless system.

However, one important issue needs to be reaffirmed and that is, for a
cellular system, F1 needs to be deployed first in the system for any geographic
area because the subscriber units hunt for the preferred channel
set in the cellular band for CDMA systems. The preferred CDMA carriers
are shown in Figure 5-11.

When looking at Figure 5-11, the secondary channels, 691 and 777, while
initially assigned and defined for IS-95 systems, are not recommended to be used due to out-of-band emissions that create a rise in the noise floor,
degrading the CDMA system performance for those particular channels.
Figure 5-11 illustrates the channel deployment scheme in a cellular or
PCS system; however, CDMA2000 will be also implemented in the SMR
band. Therefore, Figure 5-12 is an indication of the spectrum requirement
for implementing CDMA2000-1x into the specialized mobile radio (SMR)
band, which has a 25-kHz channel bandwidth. It is important to note that
the spectrum requirement requires the control of contiguious channels
within in the defined service area as well as within the guard zone itself.