Spectrum

The spectrum requirements for a CDMA2000 system have their roots in IS-
95, but some differences exist. A comparison for spectrum requirements
between IS-95, CDMA2000-1x, and CDMA2000-3x carriers is shown in Figure
4-9.
The channel depicted in Figure 4-9 indicates that for whatever version of
CDMA2000-1x the operator decides to deploy, it can be overlaid onto the
existing IS-95 channel, through a 1:1 or N:1 upgrade. The CDMA2000-1x
introduction of a reverse pilot channel as well as Walsh codes are covered in
more detail in Chapter 7, “CDMA2000.”
When the decision is made to migrate to a CDMA2000-3x system, the
operator can make two effective choices. Either the 3x system will be allocated
its own specific spectrum or the existing 1x channels will be part of
the 3X platform offering. Depending on the plan, the CDMA2000-1x channel
locations will need to be thought through in advance and this issue is
covered in Chapter 7.