Properties of guided scrambling encoders and their coded sequences

摘要

Guided scrambling (GS) line codes augment the source bit streamprior to self-synchronizing scrambling to ensure that the scramblingprocess generates an encoded bit sequence with good line codecharacteristics. With arithmetic from the ring of polynomials overGF(2), self-synchronizing scrambling can be interpreted as division ofthe source bit sequence by the scrambling polynomial and transmission ofthe resulting quotient. When augmenting bits are inserted in fixed,periodic positions, GS codes can be interpreted as block line codeswhich encode source words to quotients. In particular, block guidedscrambling (BGS) generates a transmitted bit stream which is aconcatenation of finite-length quotients chosen from sets of quotientswhich represent each source word. Alternatively, in continuous guidedscrambling (CGS), the transmitted sequence appears to be a continuousquotient due to the fact that the encoder shift registers are updatedfollowing quotient selection to contain the remainder associated withthe selected quotient. The quotient selection mechanisms of both BGS andCGS encoders can be modeled as finite state machines with quotient setsas input and the selected quotient as output. In CGS encoding, theselection mechanism also outputs the remainder associated with theselected quotient. In this paper we describe several characteristics ofGS encoders and their coded sequences