Base station device and data mapping method

A user terminal device comprising:

• a control channel receiving unit that receives a control channel signal indicating whether a modulation scheme dependent on a reception quality or a hierarchical modulation channel generated based on channel elements of channels corresponding to own user and another user is applied;
• a receiving unit that receives signals of the channels corresponding to the own user and the other user when the control channel signal received by the control channel receiving unit indicates that the hierarchical modulation channel is applied;
• and
• an extracting unit that extracts data addressed to the own user from the signals received by the receiving unit.

A data mapping method comprising:

• determining a combination of a plurality of users having different reception qualities;
• calculating a first throughput obtained when a modulation scheme dependent on a reception quality is allocated to each user;
• calculating a second throughput obtained when a hierarchical modulation channel dependent on a reception quality is allocated to each user,
• generating, when the second throughput is equal to or greater than the first throughput, a plurality of hierarchical modulation channels having different qualities based on channel elements constituting channels corresponding to the respective users in the combination determined at the determining;
• allocating the hierarchical modulation channels to the respective users such that a hierarchical modulation channel having a higher quality is allocated to a user having a lower reception quality;
• and
• mapping data for each user to the hierarchical modulation channel allocated to each user at the allocating.