Here I write about EVDO (HSD) reverse channel in short or summarize defination. The EVDO channels for the reverse connection have a similar structure as for CDMA2000.
The reverse link for 1xEV-DO has a structure similar to that for CDMA2000. In EV-DO all signalling is performed on the data channel and this means that there is no Dedicated Control Channel.
The data channel can support 5 data rates which are separated in powers of 2 from 9.6 to 153.6 kbps. These rates are achieved by varying the repeat factor. The highest rate uses a Turbo coder with lower gain. The following channels are transmitted in addition to those used with 1X:
Evolution-Data Optimized (EV-DO, EVDO, etc.) is a telecommunications standard for the channel that includes a reverse link pilot (helps decode the signal) along with the user data channels.
Reverse Rate Indicator (RRI) Channel – This indicates the data rate of the Reverse Data Channel.
Acknowledgement (Ack) Channel – This channel is transmitted after the AT detects a frame with the preamble detailing it to be the recipient of the data.
Data Rate Control (DRC) Channel – This channel contains a four bit word in each slot to allow the choice of 12 different transmission rates.
EVDO to provide packet traffic uses both the I and Q phases for data transmission in both the forward and reverse links.