User terminal, radio base station and radio communication method

Abstract

The present invention is designed to improve throughput when CA is executed between multiple cells including a TDD cell. A user terminal carries out radio communication with a plurality of cells by employing carrier aggregation, and has a receiving section that, when a connection is established with a TDD cell, receives information about a predetermined DL/UL configuration that is selected from a plurality of DL/UL configurations, and a control section that controls transmission and reception to and from the TDD cell based on the predetermined DL/UL configuration received, and a DL/UL configuration to carry out DL communication in all subframes is included as one in the plurality of DL/UL configurations, and the control section uses the DL/UL configuration to carry out DL communication in all subframes as one of the DL/UL configurations only when the connecting TDD cell is a secondary cell.

1 . A user terminal that carries out radio communication with a plurality of cells by employing carrier aggregation, the user terminal comprising:
 a receiving section that, when a connection is established with a TDD cell, receives information about a predetermined DL/UL configuration that is selected from a plurality of DL/UL configurations; and   a control section that controls transmission and reception to and from the TDD cell based on the predetermined DL/UL configuration,   wherein a DL/UL configuration to carry out DL communication in all subframes is included as one in the plurality of DL/UL configurations, and the control section uses the DL/UL configuration to carry out DL communication in all subframes as one of the DL/UL configurations only when the connecting TDD cell is a secondary cell.   
     
     
         2 . The user terminal according to  claim 1 , wherein the DL/UL configuration to carry out DL communication in all subframes is comprised entirely of DL subframes. 
     
     
         3 . The user terminal according to  claim 1 , wherein a special subframe is included in the DL/UL configuration to carry out DL communication in all subframes. 
     
     
         4 . The user terminal according to  claim 1 , wherein, when a primary cell is an FDD cell, a secondary cell is a TDD cell and the DL/UL configuration to carry out DL communication in all subframes is configured in the TDD cell, the control section sees the TDD cell as an FDD cell, and employs an A/N feedback mechanism in FDD cell-FDD cell carrier aggregation. 
     
     
         5 . The user terminal according to  claim 4 , wherein the control section feeds back an A/N in response to each DL subframe of the TDD cell by using a predetermined UL subframe of the FDD cell. 
     
     
         6 . The user terminal according to  claim 1 , wherein, when a primary cell and a secondary cell are TDD cells and the DL/UL configuration to carry out DL communication in all subframes is configured in the TDD cell that serves as the secondary cell, the control section sees the TDD cell to serve as the secondary cell as an FDD cell, and employs an A/N feedback mechanism in TDD cell-FDD cell carrier aggregation. 
     
     
         7 . The user terminal according to  claim 6 , wherein the control section controls A/N feedback so that A/Ns in response to all DL subframes of the TDD cell that serves as the secondary cell can be allocated to UL subframe of the primary cell. 
     
     
         8 . A radio base station that communicates with a user terminal by employing carrier aggregation, the radio base station comprising:
 a DL/UL configuration selection that, when a connection is established with a TDD cell, selects a predetermined DL/UL configuration, which the user terminal uses to communicate with the TDD cell, from a plurality of DL/UL configurations;   a control section that controls transmission and reception to and from the user terminal based on the predetermined DL/UL configuration,   wherein a DL/UL configuration to carry out DL communication in all subframes is included as one in the plurality of DL/UL configurations, and the DL/UL configuration selection section can select the DL/UL configuration to carry out DL communication in all subframes only when a secondary cell is configured.   
     
     
         9 . The radio base station according to  claim 8 , further comprising a transmission section that reports the predetermined DL/UL configuration to the user terminal. 
     
     
         10 . A radio communication method for a user terminal that communicates with a plurality of cells employing carrier aggregation, the radio communication method comprising the steps of:
 when a connection is established with a TDD cell, receiving information about a predetermined DL/UL configuration that is selected from a plurality of DL/UL configurations; and   controlling transmission and reception to and from the TDD cell based on the predetermined DL/UL configuration,   wherein a DL/UL configuration to carry out DL communication in all subframes is included as one in the plurality of DL/UL configurations, and the DL/UL configuration to carry out DL communication in all subframes is used as one of the DL/UL configurations only when the connecting TDD cell is a secondary cell.