Recent Advances in Coding Theory for Near Error-Free Communications

He then showed that the most efficient solution to this fundamental problem necessarily involved coding the selected message, before transmission over the channel. Shannon did not say exactly how this coding should be done; he only proved mathematically that efficient coding schemes must exist. Since 1948, a whole generation of later researchers has validated Shannon’s work by devising explicit and practical coding schemes, which are now part of practically every modern digital communication system. Near-earth satellite communication systems, high performance military systems, computer communication networks, high speed modems, and compact-disk recording and playback systems, all rely heavily on sophisticated coding schemes to enhance their performance. The communication channel which has benefitted most from Shannon’s insights, perhaps, is the deep-space channel, i.e., the channel by which spacecraft like Pioneer,Mariner, Voyager, etc., transmit their astonishing views of the Solar System back to planet Earth. In this paper we will discuss the benefits that coding has already brought to deep-space communication, and the benefits that may yet become a reality. Coding has traditionally been divided into two branches: channel coding and source coding. The goal of channel coding is to protect the transmitted message from the errors and distortions which may be caused by the channel. The goal of source coding (sometimes also called data compression), on the other hand, is to ensure that the transmitted message is as dense with information as possible. While channel coding has historically been the more important contributor to deep-space communication technology, future gains may come largely from source coding.