Terminal device, base station apparatus, communication method, and integrated circuit

1. A terminal device comprising:

transmission circuitry configured to

transmit a rank indicator (RI) for physical downlink shared channel (PDSCH) transmission, and

transmit the RI on a physical uplink shared channel (PUSCH);

reception circuitry configured to

receive first information used for determining a first maximum value of layers, the first maximum value being assumed for determining a bit width for the RI, and

receive a transport block on a PDSCH; and

decoding circuitry configured to decode that decodes a code block of the transport block,

wherein

rate matching for the code block is performed based on at least a soft buffer size for the code block,

the soft buffer size for the code block is determined based on at least the first information which is used for determining the first maximum value of the layers, and

a first transmission mode relating to the PDSCH transmission is configured.

2. The terminal device according to claim 1 , wherein

the transmission circuitry is configured to transmit capability information including second information and third information,

the second information indicates a first UE category corresponding to a second maximum value of the layers supported by the terminal device in a downlink, and corresponding to a first total number of soft channel bits which are available for hybrid automatic repeat request (HARQ) processing in the downlink,

the third information indicates a second UE category corresponding to a third maximum value of the layers supported by the terminal device in the downlink, and corresponding to a second total number of soft channel bits which are available for the hybrid automatic repeat request (HARQ) processing in the downlink, and

the soft buffer size for the code block is determined with reference to any one of the first total number and the second total number, based on whether or not the first information used for determining the first maximum value of the layers is configured to a value indicating a fourth maximum value of the layers.

3. The terminal device according to claim 2 , wherein

in a case where the first information used for determining the first maximum value of the layers is configured to the value indicating the fourth maximum value of the layers, the soft buffer size for the code block is determined with reference to the first total number, and

in a case where the first information used for determining the first maximum value of the layer is not configured to the value indicating the fourth maximum value of the layers, the soft buffer size for the code block is determined with reference to the second total number.

4. The terminal device according to claim 2 , wherein

in a case where the first information is received, the first maximum value of the layers is determined with reference to the first information.

5. The terminal device according to claim 2 , wherein

in a case where the first information is not received, the first maximum value of the layers is determined with reference to the third information.

6. A base station apparatus comprising:

reception circuitry configured to

receive a rank indicator (RI) for physical downlink shared channel (PDSCH) transmission, from a terminal device, and

receive the RI from the terminal device on a physical uplink shared channel (PUSCH);

transmission circuitry configured to

transmit first information used by the terminal device for determining a first maximum value of layers to the terminal device, the first maximum value being assumed by the terminal device in order to determine a bit width for the RI, and

transmit a transport block on a PDSCH to the terminal device; and

coding circuitry configured to code a code block of the transport block,

wherein

rate matching for the coded code block is performed based on at least a soft buffer size for the code block,

the soft buffer size for the code block is determined based on at least the first information which is used by the terminal device in order to determine the first maximum value of the layers, and

a first transmission mode relating to the PDSCH transmission is configured.

7. The base station apparatus according to claim 6 , wherein

the reception circuitry is configured to receive capability information including second information and third information from the terminal device,

the second information indicates a first UE category corresponding to a second maximum value of the layers supported by the terminal device in a downlink, and corresponding to a first total number of soft channel bits which are available for hybrid automatic repeat request (HARQ) processing in the downlink,

the third information indicates a second UE category corresponding to a third maximum value of the layers supported by the terminal device in the downlink, and corresponding to a second total number of soft channel bits which are available for the hybrid automatic repeat request (HARQ) processing in the downlink, and

the soft buffer size for the code block is determined with reference to any one of the first total number and the second total number, based on whether or not the first information used for determining the first maximum value of the layers is configured to a value indicating a fourth maximum value of the layers.

8. The base station apparatus according to claim 7 , wherein

in a case where first information used by the terminal device in order to determine the first maximum value of the layers is configured to the value indicating the fourth maximum value of the layers, the soft buffer size for the code block is determined with reference to the first total number, and

in a case where the first information used by the terminal device in order to determine the first maximum value of the layer is not configured to the value indicating the fourth maximum value of the layers, the soft buffer size for the code block is determined with reference to the second total number.

9. The base station apparatus according to claim 7 , wherein

in a case where the first information is received, the first maximum value of the layers is determined with reference to the first information.

10. The base station apparatus according to claim 7 , wherein

in a case where the first information is not received, the first maximum value of the layers is determined with reference to the third information.

11. A communication method used in a terminal device, the method comprising:

transmitting a rank indicator (RI) for physical downlink shared channel (PDSCH) transmission;

transmitting the RI on a physical uplink shared channel (PUSCH);

receiving first information used for determining a first maximum value of layers, the first maximum value being assumed for determining a bit width for the RI;

receiving a transport block on a PDSCH; and

decoding a code block of the transport block,

wherein

rate matching for the code block is performed based on at least a soft buffer size for the code block, and

the soft buffer size for the code block is determined based on at least the first information which is used for determining the first maximum value of the layers, and

a first transmission mode relating to the PDSCH transmission is configured.

12. A communication method used in a base station apparatus, the method comprising:

receiving a rank indicator (RI) for physical downlink shared channel (PDSCH) transmission, from a terminal device;

receiving the RI on a physical uplink shared channel (PUSCH);

transmitting first information used by the terminal device for determining a first maximum value of layers to the terminal device, the first maximum value being assumed by the terminal device in order to determine a bit width for the RI;

transmitting a transport block on a PDSCH to the terminal device; and

coding a code block of the transport block,

wherein

rate matching for the coded code block is performed based on at least a soft buffer size for the code block,

the soft buffer size for the code block is determined based on at least the first information which is used by the terminal device in order to determine the first maximum value of the layers, and

a first transmission mode relating to the PDSCH transmission is configured.

13. An integrated circuit configured to cause a terminal device to perform at least:

transmitting a rank indicator (RI) for physical downlink shared channel (PDSCH) transmission;

transmitting the RI on a physical uplink shared channel (PDSCH);

receiving first information used for determining a first maximum value of layers, the first maximum value being assumed for determining a bit width for the RI;

receiving a transport block on a PDSCH; and

decoding a code block of the transport block,

wherein

rate matching for the code block is performed based on at least a soft buffer size for the code block,

the soft buffer size for the code block is determined based on at least the first information which is used for determining the first maximum value of the layers, and

a first transmission mode relating to the PDSCH transmission is configured.

14. An integrated circuit configured to cause a base station apparatus to perform at least:

receiving a rank indicator (RI) for physical downlink shared channel (PDSCH) transmission, from a terminal device;

receiving the RI on a physical uplink shared channel (PDSCH);

transmitting first information used by the terminal device for determining a first maximum value of layers to the terminal device, the first maximum value being assumed by the terminal device in order to determine a bit width for the RI;

transmitting a transport block on a PDSCH to the terminal device; and

coding a code block of the transport block,

wherein

rate matching for the coded code block is performed based on at least a soft buffer size for the code block,

the soft buffer size for the code block is determined based on at least the first information which is used by the terminal device in order to determine the first maximum value of the layers, and

a first transmission mode relating to the PDSCH transmission is configured.