Data dependent scrambler with improved global constraint

摘要

A data dependent descrambler for a communications channel that receives a scrambling seed and a scrambled user data sequence with N symbols each with M bits comprises a first decoder that analyzes adjacent symbols of the scrambled user data sequence, that performs G-constraint decoding on the adjacent symbols when a first of the adjacent symbols is an all-one symbol and that does not perform G-constraint encoding when the first of the adjacent symbols is not an all-one symbol. A first descrambler communicates with the first decoder and generates a user data sequence based on the scrambled user data sequence and the scrambling seed.