Traffic Channels (TCH)

Traffic Channels (TCH)
TCHs carry either speech or data. There are two types of traffic channels: Full
Rate (FR) and Half Rate (HR). The TCH can be located in any timeslot on any
frequency defined in the cell, except for the first timeslot (TS0) on the first carrier
(C0).
Full Rate (FR) – The Full Rate Traffic Channel (TCH/F) handles encoded
speech or data. The TCH information is transmitted at a gross rate of 22.8 kbps.
Enhanced Full Rate (EFR) provides a slight improvement in the transmission rate
of voice (12.2 kbps).
Half Rate (HR) – With a Half Rate Traffic Channel (TCH/H), a mobile station
will only use every second timeslot (every other one is idle). The TCH
information is transmitted at a gross rate of 14.4 kbps. As a result, two mobile
stations are able to use the same physical channel for calls, leading to a doubling
of the capacity on the channel.