Frequency Reuse

The modulation scheme utilized by the NADC TDMA system is a pi/4
DQPSK format. The C/I levels used for frequency management associated
with IS-54 or IS-136 are the same for analog, 17 dB C/I. The C/I level
desired is 17 dB and is the same for DCCH and the DTC. This is convenient
because in all the cellular systems, the majority of the channels are analog
and they too require a minimum of 17 dB C/I. The fundamental issue here
is that the same D/R ratios can and are used when implementing the radio
channel assignments for digital.
The additional parameters associated with IS-136/IS-54 involve SDCC,
DCC, and DVCC. The DCC is the Digital Color Code, SDCC is the Supplementary
Digital Color Code, and DVCC is the Digital Verification Color
Code.
DCC and SDCC must be assigned to each sector, cell, or control channel
of the system that utilizes IS-136/IS-54. The DCC is used by analog and
dual-mode phones for accessing the system. The SDCC is used by dualmode
phones only and should be assigned to each control channel along
with the DCC.