Development of Point to Multipoint Time Division Multiple Access System

Abstract

A Time Division Multiple Access (TDMA) system for point-to-multipoint communications particularly useful in suburban and rural areas is under development at Gujarat Communications & Electronics Limited (GCEL). The system operates in the UHF frequency band of 1.427 GHz to 1.525 GHz and makes use of a single pair of radio frequencies for communication between a large number of subscribers. This is achieved by concentrating the large number of subscribers(128)into a few Voice/Data channels (300) and assigning the channels on demand to the subscribers. Individual voice channels are transmitted in time division mode making use of a single radio frequency channel.The system when integrated with the public telephone network will enable a subscriber of the system to be connected to any where in the world. The use of digital Pulse Code Modulation (PCM) technique combined with Quaternary Phase Shift Keyed (QPSK) modulation technique offers good quality of speech as well as spectrum economy.This paper describes the ...