Communication system, base station apparatus, and mobile station apparatus

A base station apparatus which performs radio communication with a mobile station apparatus using a plurality of frequency layers having frequency bands different from each other, said base station apparatus comprising:

• a determination unit which determines a downlink channel status of said mobile station apparatus and a communication requirement of said mobile station apparatus;
• and
• a mapping unit which assigns a downlink cell common control channel and a downlink cell common traffic channel to a low-frequency layer and assigns a downlink cell dedicated control channel and a downlink cell dedicated traffic channel to a low-frequency layer and/or a high-frequency layer based on a downlink channel status of a mobile station apparatus and a communication requirement of said mobile station apparatus as a result of said determination.

A mobile station apparatus which performs radio communication with a base station apparatus using a plurality of frequency layers having frequency bands different from each other, wherein said mobile station apparatus

• receives from said base station apparatus a downlink cell common control channel and a downlink cell common traffic channel assigned to a low-frequency layer, and
• receives from said base station apparatus a downlink cell dedicated control channel and a downlink cell dedicated traffic channel assigned to a low-frequency layer and/or a high-frequency layer according to a downlink channel status and a communication requirement.