TDMA/FDD Standards

TDMA/FDD Standards

(a) Global System for Mobile (GSM): The GSM standard, introduced by Groupe
Special Mobile, was aimed at designing a uniform pan-European mobile system. It
was the rst fully digital system utilizing the 900 MHz frequency band. The initial
GSM had 200 KHz radio channels, 8 full-rate or 16 half-rate TDMA channels per
carrier, encryption of speech, low speed data services and support for SMS for which
it gained quick popularity.
(b) Interim Standard 136 (IS-136): It was popularly known as North American
Digital Cellular (NADC) system. In this system, there were 3 full-rate TDMA users
over each 30 KHz channel. The need of this system was mainly to increase the
capacity over the earlier analog (AMPS) system.
(c) Pacic Digital Cellular (PDC): This standard was developed as the counterpart
of NADC in Japan. The main advantage of this standard was its low transmission
bit rate which led to its better spectrum utilization.