Channel coding is the technique of protecting message
signals from signal impairments by adding redundancy to the message
signal. In a communications system, error control is necessary for
messages that require high reliability, or if the transmission medium
is prone to error. Messages requiring high reliability include data
with no internal redundancy, control signals, and voice or video
signals that have undergone efficient source coding.
Channel coding
in CDMA operates by applying a half-rate convolutional code to
the input data, and interleaving the output. The interleaving used
in CDMA:
spreads burst errors (due to Raleigh fading) over a
longer period, reducing the reduce peak bit error rate, and
allows
the channel coding to correct the (now) randomly
spaced bit errors.
Other topics in our resources on CDMA related to Channel Coding include: