Terminal device, base station device, transmission method and transmit power setting method

A base station apparatus, comprising:

• a transmitting section that transmits, to a terminal apparatus, a request for reporting of downlink channel state information (CSI), and downlink control information (DCI) including a request for transmission of a sounding reference signal (SRS) in one of a plurality of DCI formats, the plurality of DCI formats including DCI format 0 that includes uplink assignment information and DCI format 1A that includes downlink assignment information;
• and
• a receiving section that receives the SRS transmitted with transmission power that is set based on the reporting request, a DCI format in which the transmission request is included, and a parameter for setting an initial value of transmission power control (TPC) command used for calculating the transmission power, the parameter being indicated in a random access procedure, the parameter for a terminal served by a macrocell being larger than a previously set threshold and the parameter for a terminal served by a picocell being equal to or less than the threshold, wherein:
• first transmission power is set for the SRS when the reporting request indicates a request for reporting of downlink CSI between the terminal apparatus and each of a plurality of base stations, the transmission request is included in the DCI format 1A, and the parameter is equal to or less than the threshold;
• and
• the second transmission power is set for the SRS when the reporting request indicates a request for reporting of downlink CSI between the terminal apparatus and a single base station, when the transmission request is included in the DCI format 0, or when the parameter is greater than the threshold;
• and
• the first transmission power is larger than the second transmission power.

A transmission method comprising:

• receiving a request for reporting of downlink channel state information (CSI), and downlink control information (DCI) including a request for transmission of a sounding reference signal (SRS) in one of a plurality of DCI formats, the plurality of DCI formats including DCI format 0 that includes uplink assignment information and DCI format 1A that includes downlink assignment information;
• and
• transmitting the SRS with first transmission power when the reporting request indicates a request for reporting of downlink CSI between the terminal apparatus and each of a plurality of base stations, the transmission request is included in the DCI format 1A, and a parameter for setting an initial value of transmission power control (TPC) command used for calculating the transmission power is equal to or less than a previously set threshold, the parameter being indicated in a random access procedure, the parameter for a terminal served by a macrocell being larger than a previously set threshold and the parameter for a terminal served by a picocell being equal to or less than the threshold, and
• transmitting the SRS with second transmission power when the reporting request indicates a request for reporting of downlink CSI between the terminal apparatus and a single base station, when the transmission request is included in the DCI format 0, or when the parameter is greater than the threshold, wherein
• the first transmission power is larger than the second transmission power.

A transmission power setting method, comprising:

• transmitting, to a terminal apparatus, request for reporting of downlink channel state information (CSI), and downlink control information (DCI) including a request for transmission of a sounding reference signal (SRS) in one of a plurality of DCI formats, the plurality of DCI formats including DCI format 0 that includes uplink assignment information and DCI format 1A that includes downlink assignment information;
• and
• receiving the SRS transmitted with transmission power that is set based on the reporting request, a DCI format in which the transmission request is included, and a parameter for setting an initial value of transmission power control (TPC) command used for calculating the transmission power the parameter being indicated in a random access procedure, the parameter for a terminal served by a macrocell being larger than a previously set threshold and the parameter for a terminal served by a picocell being equal to or less than the threshold, wherein
• first transmission power is set for the SRS when the reporting request indicates a request for reporting of downlink CSI between the terminal apparatus and each of a plurality of base stations, the transmission request is included in the DCI format 1A, and the parameter is equal to or less than the threshold;
• and
• second transmission power is set for the SRS when the reporting request indicates a request for reporting of downlink CSI between the terminal apparatus and a single base station, when the transmission request is included in the DCI format 0, or when the parameter is greater than the threshold, wherein
• the first transmission power is larger than the second transmission power.