Patent ID: 8229021

Claim:
A data transmission system that maps coded bits onto a modulation symbol using a multilevel modulation system and then transmits the same, wherein: there is provided a bit mapping means that maps the coded bits onto specific bit positions on the modulation symbol in accordance with the degree of importance of the coded bits; the bit mapping means maps coded bits that have a higher degree of importance onto bit positions of the modulation symbol where it is difficult for an error to occur; and the bit positions where it is difficult for an error to occur are obtained as being those bit positions where there is a higher probability of obtaining a longer least squares distance, in a constellation diagram of the multilevel modulation system, from a result of a calculation that an absolute value of the difference between a least squares distance between a signal point where reception is possible and a signal point having a bit position of 0, and a least squares distance between a signal point where reception is possible and a signal point having a bit position of 1 is calculated for all signal points where reception is possible.