Codan Radio P25 Training Guide - Manual (Page 94)

TRAINING GUIDE | P25 RADIO SYSTEMS
Chapter 7: P25 Phase 2 Page 86
TDMA VS FDMA RADIO ACCESS TECHNOLOGIES
Radio access technology is used by radio systems to share the radio spectrum. The terminology
“multiple access” implies the sharing of the resource amongst users, and the “division” describes how
the sharing is done.
Frequency Division Multiple Access (FDMA)
Frequency Division Multiple Access is a process of allowing mobile radios to share radio frequency
allocation by dividing up that allocation into separate radio channels where each radio device can
communicate on a single radio channel during communication. FDMA is the technology used for P25
Phase 1 radio systems. When a device is communicating on an FDMA system using a frequency carrier
signal, its carrier channel is completely occupied by the transmission of the device. Figure 7-1 shows
how a frequency band can be divided into two communication channels using FDMA.
Figure 7-1: Frequency Division Multiple Access
Frequency 1
(12.5 KHz)
Channel 1
Channel 2
Frequency 2
(12.5 KHz)
time
Channel 1
Channel 2