Traffic Channel (TCH)

Traffic Channel (TCH):

Traffic channels carry digitally encoded user data or user speech on the forward and reverse links.

A TCH is a group of 26 consecutive TDMA frames, called a multi frame of the 26 TDMA frames, 24 are used as TCH frames, one frame (13th) is for SACCH and 26th is the unused or idle frame.

Traffic Channel (TCH)

Traffic Channel (TCH) supports two types of information rates. They are:

(i) Full rate (TCH/F)

(ii) Half rate (TCH/H)

When transmitted at full rate, the user data is occupied within TS per frame. When transmitted at half rate, the user data is occupied into the same time slot but sent in alternate frames.

The 26th frame contains idle bits if full rate TCHs are used and contains SACCH data if half-rate TCHs are used.