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 GSM
operates by coding each 240 bit block of data in
a GSM full-rate data channel with a half-rate punctured convolutional
code to produce 456 bits that are interleaved across four
114-bit time division multiple access (TDMA) frames.The interleaving used in
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 GSM related to Channel Coding include: