Self-synchronizing code

Not to be confused with Self-clocking signal or Self-similar process.

In coding theory, especially in telecommunications, a self-synchronizing code is a uniquely decodable code in which the symbol stream formed by a portion of one code word, or by the overlapped portion of any two adjacent code words, is not a valid code word.[1] Put another way, a set of strings (called "code words") over an alphabet is called a self-synchronizing code if for each string obtained by concatenating two code words, the substring starting at the second symbol and ending at the second-last symbol does not contain any code word as substring. Every self-synchronizing code is a prefix code, but not all prefix codes are self-synchronizing.

Other terms for self-synchronizing code are synchronized code[2] or, ambiguously, comma-free code.[3] A self-synchronizing code permits the proper framing of transmitted code words provided that no uncorrected errors occur in the symbol stream; external synchronization is not required. Self-synchronizing codes also allow recovery from uncorrected errors in the stream; with most prefix codes, an uncorrected error in a single bit may propagate errors further in the stream and make the subsequent data corrupted.

Importance of self-synchronizing codes is not limited to data transmission. Self-synchronization also facilitates some cases of data recovery, for example of a digitally encoded text.

  1. ^ Cite error: The named reference Glossary was invoked but never defined (see the help page).
  2. ^ Cite error: The named reference Brestel-Perrin-Reutenauer_2010 was invoked but never defined (see the help page).
  3. ^ Cite error: The named reference Brestel-Perrin_1985 was invoked but never defined (see the help page).