Base station, mobile station, and method of communicating for controlling a transmission time interval

A mobile station apparatus, comprising:

• a receiving unit which receives a TTI and a number of subframes making up the TTI that are reported from a base station apparatus wherein it is determined whether data is to be transmitted in a first TTI with, as a unit, a predetermined period no shorter than a subframe length, or in a second TTI with, as a unit, a period shorter than the first TTI, a number of subframes making up the determined TTI is determined, and the determined TTI and the number of subframes making up the determined TTI is reported to the mobile station;
• and
• a decoding unit which decodes a shared data channel which is transmitted from the base station apparatus based on the reported TTI and the number of subframes making up the TTI,
• wherein, when a number of errors and/or an error rate of a L1/L2 control channel is no less than a predetermined threshold, the data is transmitted in the first TTI, and, when the number of errors and/or error rate of the L1/L2 control channel is less than the predetermined threshold, the data is transmitted in the second TTI.

A method of communicating, comprising:

• a TTI-length determining step of determining, by a base station apparatus, whether data is to be transmitted in a first TTI with, as a unit, a predetermined period no shorter than a subframe length, or in a second TTI with, as a unit, a period shorter than the first TTI, based on a number of errors and/or an error rate of a L1/L2 control channel transmitted from a mobile station apparatus;
• a number-of-subframes determining step of determining, by the base station apparatus, a number of subframes making up the determined TTI;
• a reporting step of reporting, by the base station apparatus, the determined TTI and the number of subframes making up the determined TTI to the mobile station apparatus;
• a scheduling step of performing, by the base station apparatus, scheduling based on the determined TTI and the number of subframes making up the determined TTI;
• a receiving step of receiving, by the base station apparatus, the reported TTI and the number of subframes making up the TTI;
• and a decoding step of decoding, by the mobile station apparatus, a shared data channel which is transmitted from the base station based on the reported TTI and the number of subframes making up the TTI,
• wherein, when the number of errors and/or the error rate of the L1/L2 control channel is no less than a predetermined threshold, the data is transmitted in the first TTI, and, when the number of errors and/or error rate of the L1/L2 control channel is less than the predetermined threshold, the data is transmitted in the second TTI.