Introduction iDEN

Introduction
iDEN is a mobile telecommunications technology, developed by Motorola, which provides its users the benefits of a trunked radio and a cellular telephone. iDEN places more users in a given spectral space, compared to analog cellular and two-way radio systems, by using speech compression and time division multiple access TDMA. Notably, iDEN is designed, and licensed, to operate on individual frequencies that may not be contiguous. iDEN operates on 25kHz channels, but only occupies 20 kHz in order to provide interference protection via guard bands. By comparison, TDMA Cellular (IS-54 and IS-136) is licensed in blocks of 30 kHz channels, but each emission occupies 40 kHz,and is capable of serving the same number of subscribers per channel as iDEN. iDEN supports either three or six interconnect users (phone users) per channel, and either six or twelve dispatch users (push-to-talk users) per channel. Since there is no Analogue component of iDEN, mechanical duplexing in the handset is unnecessary, so Time Domain Duplexing is used instead, the same way that other digital-only technolgies duplex their handsets. Also, like other digital-only technologies, hybrid or cavity duplexing is used at the Base Station (Cellsite).