Turbo codes
Turbo codes are a class of recently-developed high-performance error correction codes finding use in deep-space satellite communications and other applications where designers seek to achieve maximal information transfer over a limited-bandwidth communication link in the presence of data-corrupting noise. Of all practical error correction methods known to date, turbo codes come closest to approaching the Shannon limit, the theoretical limit of maximum information transfer rate over a noisy channel.The method was introduced by Berrou, Glavieux, and Thitimajshima in their 1993 paper: "Near Shannon Limit error-correcting coding and decoding: Turbo-codes" published in the Proceedings of IEEE International Communications Conference. Turbo code refinements and implementation are an area of active research at a number of universities.
Turbo codes make it possible to increase available bandwidth without increasing the power of a transmission, or they can be used to decrease the amount of power used to transmit at a certain data rate.
Prior to Turbo codes, the best known technique combined a Reed-Solomon error correction block code with a Viterbi algorithm convolutional code.