Error detection and correction
Serial concatenated convolutional codes
Serial concatenated convolutional codes (SCCC) are a class of forward error correction (FEC) codes highly suitable for turbo (iterative) decoding. Data to be transmitted over a noisy channel may first be encoded using an SCCC. Upon reception, the coding may be used to remove any errors introduced during transmission. The decoding is performed by repeated decoding and [de]interleaving of the received symbols. SCCCs typically include an inner code, an outer code, and a linking interleaver. A distinguishing feature of SCCCs is the use of a recursive convolutional code as the inner code. The recursive inner code provides the 'interleaver gain' for the SCCC, which is the source of the excellent performance of these codes. The analysis of SCCCs was spawned in part by the earlier discovery of turbo codes in 1993. This analysis of SCCC's took place in the 1990s in a series of publications from NASA's Jet Propulsion Laboratory (JPL). The research offered SCCC's as a form of turbo-like serial concatenated codes that 1) were iteratively ('turbo') decodable with reasonable complexity, and 2) gave error correction performance comparable with the turbo codes. Prior forms of serial concatenated codes typically did not use recursive inner codes. Additionally, the constituent codes used in prior forms of serial concatenated codes were generally too complex for reasonable soft-in-soft-out (SISO) decoding. SISO decoding is considered essential for turbo decoding. Serial concatenated convolutional codes have not found widespread commercial use, although they were proposed for communications standards such as DVB-S2. Nonetheless, the analysis of SCCCs has provided insight into the performance and bounds of all types of iterative decodable codes including turbo codes and LDPC codes. US patent 6,023,783 covers some forms of SCCCs. The patent expired on May 15, 2016. (Wikipedia).
