Apparatus and method for adjusting an input range for a soft-decision decoder

A method for adjusting an expression section of input bit values according to the number of input bits in a mobile communication system that expresses only a defined partial section of the input bit values in order to make the number of output bits be smaller than the number of the input bits, and maps bit values included in unexpressed sections to a specific value, the method comprising the steps of:

• (a) dividing output bit values into at least three sections, and measuring output frequencies of output bit values for the respective sections for a predetermined time;
• and
• (b) adjusting the expression section, when an output frequency for a specific section is higher than the output frequencies for other sections,
• wherein the desired expression section is adjusted according to the number of input bit values mapped to one output bit value and the number of input bit values mapped to the one output bit value is proportional to a range of a desired expression section.

An apparatus for adjusting a desired expression section of input bit values according to the number of input bits in a mobile communication system that expresses only a defined partial section of the bit values in order to make the number of output bits smaller than the number of the input bits, and maps bit values included in unexpressed sections to a specific value, the apparatus comprising:

• a measurer for dividing possible output bit values into at least three sections, and measuring output frequencies of the output bits values for the respective sections for a predetermined time;
• and
• a controller for adjusting the expression section, when an output frequency for a specific section is higher than the output frequencies for other sections,
• wherein the controller adjusts the desired expression section according to the number of input bit values mapped to one output bit value and the number of input bit values mapped to the one output bit value is proportional to a range of the desired expression section.