Method and apparatus for reproducing data and method and apparatus for recording and/or reproducing data

A data reproducing method for reproducing data recorded by a recording method for recording data on a recording medium including a modulation encoding step of applying predetermined modulation encoding to input data having a bit sequence, encoding the input data in accordance with a constraint condition using block modulation, and a first interleaving step of interleaving data encoded in said modulation encoding step, for re-arraying a data sequence corresponding to said data encoded in said modulation encoding step, said data reproduction method comprising the steps of:

• deinterleaving the input data in a sequence such as to restore the data sequence to the bit sequence;
• modulation decoding data supplied from said step of deinterleaving, in conformance with said constraint condition, wherein the step of modulation decoding further includes a likelihood calculating step of calculating a likelihood value of output codewords generated and output by said modulation encoding step;
• calculating posterior probability information as a soft decision value for an input bit to said modulation encoding step and an output bit from said modulation encoding step using said likelihood value as calculated by said likelihood calculating step;
• and
• interleaving difference data corresponding to a difference between data decoded in said modulation encoding step and data re-arrayed in said step of deinterleaving, based on the same interleaving position information as that of said first interleaving step, for re-arraying the sequence of the difference data.

A data recording and reproducing apparatus for recording and reproducing data for a recording medium, said apparatus comprising:

• modulation encoding means for applying predetermined modulation encoding to input data having a bit sequence, wherein said modulation encoding means encodes the input data in accordance with a constraint condition by block modulation;
• first interleaving means for interleaving data supplied from said modulation encoding means for re-arraying a data sequence corresponding to said data supplied from said modulation encoding means;
• deinterleaving means for deinterleaving reproduced data in a sequence such as to restore the data sequence to the bit sequence;
• modulation decoding means for modulation decoding data supplied from said deinterleaving means in conformance with said constraint condition, wherein said modulation decoding means further includes:
• likelihood calculating means for calculating a likelihood value corresponding to output codewords output by said modulation encoding means, wherein posterior probability information as a soft decision value for an input bit to said modulation encoding means and an output bit from said modulation encoding means is calculated using said likelihood value as calculated by said likelihood calculating means;
• and
• second interleaving means for interleaving difference data corresponding to a difference between data output by said modulation decoding means and data output by said deinterleaving means, based on the same interleaving position information as that of said first interleaving means, for re-arraying the sequence of the difference data.

A data recording and reproducing method for recording and reproducing data for a recording medium, said method comprising the steps of:

• applying predetermined modulation encoding to input data having a bit sequence, wherein said modulation encoding encodes the input data in accordance with a constraint condition by block modulation;
• interleaving the modulation-encoded data for re-arraying a data sequence corresponding to the modulation-encoded data;
• deinterleaving reproduced data in a sequence such as to restore the data sequence to the bit sequence;
• modulation decoding the data supplied from said step of deinterleaving in accordance with said constraint condition, wherein said step of modulation decoding further includes a likelihood calculating step for calculating a likelihood value corresponding to each output codeword output by said modulation encoding step;
• calculating posterior probability information as a soft decision value for an input bit to said step of applying and an output bit from said step of applying using said likelihood value as calculated by said likelihood calculating step;
• and
• interleaving difference data corresponding to a difference between data decoded in said step of modulation decoding and data re-arrayed in said step of deinterleaving based on the same interleaving position information as that of said step of interleaving the modulation-encoded data.