Feedback method, mobile terminal apparatus and radio base station apparatus

A mobile terminal apparatus comprising:

• a feedback information selection section that, in a mode to include a PTI (Precoder Type Indicator) in a physical uplink control channel and feed back the PTI to a radio base station apparatus for downlink MIMO (Multiple-Input and Multiple-Output) transmission using a plurality of transmitting antennas, selects a same RI (Rank Indicator) as a last RI that was fed back, when the value of the PTI on a subframe is changed from 0 to 1;
• a multiplexing section that multiplexes the RI and the PTI after the change to generate a multiplex signal;
• and
• a transmission section that transmits the multiplex signal to the radio base station apparatus by the physical uplink control channel.

A feedback method of including a PTI (Precoder Type Indicator) in a physical uplink control channel and feeding back the PTI to a radio base station apparatus for downlink MIMO (Multiple-Input and Multiple-Output) transmission using a plurality of transmitting antennas, the feedback method comprising the steps of:

• selecting 0 for the value of the PTI on a subframe when a different RI (Rank Indicator) from a last RI that was fed back is selected;
• multiplexing the PTI and the RI after the different RI from the last RI is selected to generate a multiplex signal;
• and
• transmitting the multiplex signal to the radio base station apparatus by the physical uplink control channel.

A feedback method of including a PTI (Precoder Type Indicator) in a physical uplink control channel and feeding back the PTI to a radio base station apparatus for downlink MIMO (Multiple-Input and Multiple-Output) transmission using a plurality of transmitting antennas, the feedback method comprising the steps of:

• in a radio base station apparatus, storing in advance a virtual PMI (Precoding Matrix Indicator) to be used as a wideband first PMI, depending on an RI (Rank Indicator);
• in a mobile terminal apparatus, selecting a different RI from a last RI that was fed back when 1 is selected for the value of the PTI on a subframe, and multiplexing the PTI and the different RI from the last RI to generate a multiplex signal;
• transmitting the multiplex signal to the radio base station apparatus by the physical uplink control channel;
• and
• in the radio base station apparatus, using the virtual PMI to match the different RI from the last RI is fed back to generate a precoding weight.

A feedback method of including a PTI (Precoder Type Indicator) in a physical uplink control channel and feeding back the PTI to a radio base station apparatus for downlink MIMO (Multiple-Input and Multiple-Output) transmission using a plurality of transmitting antennas, the feedback method comprising the steps of:

• in a radio base station apparatus, storing in advance a virtual PMI (Precoding Matrix Indicator) to be used as a wideband first PMI, depending on a combination of a last RI (Rank Indicator) and wideband first PMI that were fed back and a different RI from the last RI;
• in a mobile terminal apparatus, when the different RI from the last RI that was fed back is selected and 1 is selected for the value of tile PTI on a subframe, multiplexing the PTI and the different RI from the last RI to generate a multiplex signal;
• transmitting the multiplex signal to the radio base station apparatus by the physical uplink control channel;
• and
• in the radio base station apparatus, using the virtual PMI to match the different RI from the last RI is fed and the last RI and wideband first PMI that were fed back, to generate a precoding weight.