CONNECTION BETWEEN BLOCK AND CONVOLUTIONAL CODES

Convolutional codes of any rate and any constraint length give rise to a sequence of quasi-cyclic codes. Conversely, any quasi-cyclic code may be convolutionally encoded. Among the quasi-cyclic codes are the quadratic residue codes, Reed-Solomon codes and optimal BCH codes. The constraint length K for the convolutional encoding of many of these codes (Golay, (48,24) QR, etc. ) turns out to be surprisingly small. Thus using the soft decoding techniques for convolutional decoding provides a new maximum likelihood decoding algorithm for many block codes. Conversely an optimal quasi-cyclic code will yield a convolutional encoding with optimal local properties and therefore with good infinite convolutional coding properties. 6 refs.