Introduction to redundancy coding

An introduction to redundancy encoding as used in digital data communications is described. The need for redundancy is first addressed, followed by a discussion of the binary symmetric channel, burst noise channels, and the use of interleaving to randomize burst errors. The concept of redundancy is presented next, showing how it is used to supply the highest possible degree of error detection or how it can be applied to provide for the detection and correction of a lesser number of errors. The use of some codes to correct some errors and also to detect, but not correct, additional errors is discussed. The properties of block codes are developed beginning with repetition codes then covering single-parity check codes, Hamming (single-error detection) codes, and Bose-Chadhuri-Hocquenghem (BCH)codes. The basic properties and structures of these codes are emphasized with examples of implementation procedures for both encoding and decoding.