Editing IDEN (section)

== Operating frequencies ==
iDEN is designed and licensed to operate on individual frequencies that may not be contiguous. iDEN operates on 25&nbsp;kHz channels, but only occupies 20&nbsp;kHz in order to provide interference protection via [[guard band]]s. By comparison, TDMA Cellular ([[Digital AMPS]]) is licensed in blocks of 30&nbsp;kHz channels, but each emission occupies 40&nbsp;kHz, and is capable of serving the same number of subscribers per channel as iDEN. iDEN uses [[Duplex (telecommunications)#Frequency-division duplexing|frequency-division duplexing]] to transmit and receive signals separately, with transmit and receive bands separated by 39&nbsp;MHz, 45&nbsp;MHz, or 48&nbsp;MHz depending on the frequency band being used.

iDEN supports either three or six interconnect users (phone users) per channel, and six dispatch users (push-to-talk users) per channel, using [[time-division multiple access]]. The transmit and receive time slots assigned to each user are deliberately offset in time so that a single user never needs to transmit and receive at the same time. This eliminates the need for a [[duplexer]] at the mobile end, since [[Duplex (telecommunications)#Time-division duplexing|time-division duplexing]] of RF section usage can be performed.