User Guide

Technical Documentation
NHD–4
System Overview
PAMS
Page 3–19
Original 11/97
The AMPS, DAMPS, and GSM capacity examples in figure 17 assume that only one
channel out of every seven can be used. In a crowded metropolitan area, cellular
base stations are arranged like the top part of figure 18. Each base station is
surrounded by seven others so only one out every 7 channels can be used or
adjacent channel interference will occur. However, such is not the case for CDMA
because all users on a “CDMA Channel” operate on the same frequency. I’ve just
used the word “Channel” in a different way. Users in a given CDMA channel are
separated by different PN code sequences. According to information at the present
time there four designated CDMA frequency channels, so users on a given
frequency channel operate on the same frequency and are separated by different
PN code sequences which are also called “Channels”.
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CDMA Cell Structure
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Transmission range of
any given celll
Transmission range of
any given cell
CDMA03.DRW
Figure 18. Analog, TDMA & CDMA Structure
ANALOG & TDMA Cell Structure