Terminal, radio base station, and radio communication method for communicating

A base station that communicates with a terminal that can use

• a plurality of cells including cells using TDD, the radio base station comprising:
• a transmitter configured to transmit first information, indicating a total number of cells to be subjected to DL transmission scheduling in a radio resource over a plurality of cells and a plurality of time domains, and second information, indicating an accumulative number of cells, in downlink control information;
• and
• a receiver configured to receive HARQ-ACKs transmitted from the terminal based on the first information and the second information,
• wherein the first information is configured to a same value within the plurality of cells in a time domain of the radio resource, and the first information is updated on a per resource range basis,
• wherein a number of bits of the HARQ-ACKs are determined based on the first information included in the downlink control information in a last time domain of the radio resource in which a DL signal is transmitted in the radio resource,
• wherein HARQ-ACKs to be configured at each bit position in a codebook are determined based on the second information, and
• wherein the size of the codebook is determined based on the first information.

A radio communication method for a terminal that communicates with a radio base station, the radio communication method comprising:

• transmitting HARQ-ACKs in response to DL signals transmitted from a plurality of cells including cells using TDD;
• receiving first information, indicating a total number of cells to be subjected to DL transmission scheduling in a radio resource over a plurality of cells and a plurality of time domains, and second information, indicating an accumulative number of cells, in downlink control information;
• and
• performing control so that the HARQ-ACKs are transmitted based on the first information and the second information,
• wherein the first information is configured to a same value in the plurality of cells in a time domain of the radio resource, and the first information is updated on a per time domain basis of the radio resource,
• wherein the terminal determines a number of bits of the HARQ-ACKs based on the first information included in the downlink control information in a last time domain of the radio resource in which a DL signal is received in the radio resource,
• wherein the user terminal determines HARQ-ACKs to be configured at each bit position in a codebook based on the second information, and
• wherein the size of the codebook is determined based on the first information.