ENCODING AND DECODING APPARATUS AND CORRESPONDING METHODS

摘要

The present invention relates to an encoding apparatus and method for encoding a user data stream (m) into a channel data stream (y) as well as to a corresponding decoding apparatus and method. To improve the worst case BER behavior of storage systems and increase reliability, in particular which ensure a low BER without a large loss of information rate, particularly in two-dimensional optical storage systems or in communication systems, an encoding apparatus is proposed according to the invention which comprises: an expansion unit for transforming said user data stream (m) to an intermediate data stream (i) comprising at least one more symbol than said user data stream (m), a processing unit (100, 200, 500, 600) for iteratively determining for each scrambling stream (c) from a scrambling code (C) the value (v) of a figure of merit for the scrambling stream (c) using said intermediate data stream (i), a selection unit (300) for selecting an optimum merit value (v_opt) from said merit values (v) and for selecting an optimum scrambling stream (ç opt) for which the figure of merit equals said optimum merit value (v_opt), and at least one mapping unit (400) for mapping the symbols of said optimum scrambling stream (ç opt) onto the corresponding symbols of said intermediate data stream (i) to obtain said channel data stream (y) for output to a channel.