Soft demodulation method and apparatus

A soft demodulation apparatus, comprising:

• a partial sum calculator, which calculates partial sums for a unit of each predetermined number of bits of a codeword received from a channel;
• an entry calculator, which calculates a value of each entry of a decoding table by referring to the partial sums;
• a maximum detector, which detects a maximum among values of all calculated entries of the decoding table;
• and
• a log-likelihood ratio (LLR) calculator, which calculates an LLR using the detected maximum.

An optical signal processing apparatus of an optical disc device, comprising:

• a read/write unit to output a read code signal from an optical disc in the optical disc device;
• a reference entry unit which stores a predetermined number of reference entries;
• a partial sum calculator which calculates partial sums of n-bit portions of the read code signal received from the read/write unit corresponding to each stored reference entry;
• a partial sum table which stores the calculated partial sums corresponding to each n-bit portion of the read code signal;
• an entry calculator which calculates an entry value of each entry of a decoding table by summing the corresponding calculated partial sums stored in the partial sum table that correspond to an n-bit portion of the decoding table entry;
• a maximum detector which detects a maximum calculated entry value;
• and
• a log-likelihood ratio (LLR) calculator, which calculates an LLR using the detected maximum.

A soft demodulation method, comprising:

• storing predetermined reference entries;
• calculating partial sums corresponding to n-bit portions of a read code signal based on the stored predetermined reference entries;
• storing the calculated partial sums;
• calculating an entry value of each entry of a decoding table by adding the stored calculated partial sums which correspond to consecutive n-bit portions of the entry of the decoding table;
• detecting a maximum entry value;
• and
• calculating a log-likelihood ratio based on the detected maximum entry value.

A soft demodulation method, comprising:

• calculating partial sums corresponding to a codeword;
• calculating a predetermined entry value of a decoding table, by adding the partial sums, wherein the partial sums are abandoned when the partial sums are less likely to be detected as a maximum and the partial sums are added together to calculate the predetermined entry value when the partial sums are more likely to be detected as a maximum;
• and
• detecting a maximum among the calculated predetermined entry values of the decoding table and calculating a log-likelihood ratio (LLR) using the detected maximum.