II. FORWARD ERROR CORRECTION CODES
In communication, information and coding theory, errorcontrol technique is used for controlling errors in data
transmission over unreliable or noisy communication channels
to provide robust data transmission through imperfect channel
by adding redundancy to the data according to predetermined
algorithm. The redundancy allows the receiver to detect a
limited number of errors that may occur anywhere in the
message, and often to correct these errors without
retransmission. Forward Error correction (FEC) is the key
ingredient for improving reliability of modern digital
communication and storage systems and to guarantee data
integrity. FEC gives the receiver the ability to correct errors
without needing a reverse channel to request retransmission of
data, but at the cost of a fixed, higher forward channel
bandwidth. FEC is therefore applied in situations where
retransmissions are costly or impossible, such as when
broadcasting to multiple receivers in multicast. Design of the
FEC code determine maximum fractions of errors or of
missing bits that can be corrected, so different forward error
correcting codes are suitable for different applications.
Designers have tradeoffs to consider when choosing a FEC
code for a transmission system such as power, FEC
complexity, and FEC performance, etc.