User terminal and radio communication method

Abstract

The present invention is designed to execute retransmission control that is suitable for contention-based UL transmission. A user terminal, according to the present invention, has a transmission section that transmits uplink (UL) data, and a control section that controls retransmission of the UL data, and the control section controls the retransmission of the UL data based on retransmission command information, which provides a retransmission command for the UL data by a frequency resource, or by a resource group, which includes the frequency resources.

1 . A user terminal comprising:
 a transmission section that transmits uplink (UL) data; and   a control section that controls retransmission of the UL data,   wherein the control section controls the retransmission of the UL data based on retransmission command information, which provides a retransmission command for the UL data by a frequency resource, or by a resource group, which includes the frequency resource.   
     
     
         2 . The user terminal according to  claim 1 , wherein the retransmission command information provides a retransmission command by one or more time resource unit, and/or by terminal group unit where one or more user terminals belong. 
     
     
         3 . The user terminal according to  claim 1 , wherein the retransmission command information is transmitted to the user terminal by using a dedicated resource, which is specific to the frequency resource or the resource group, or by using a common resource, which is common to the frequency resource or the resource group. 
     
     
         4 . The user terminal according to  claim 1 , wherein a transmission time interval (TTI), in which the UL data is transmitted, is comprised of a UL period, which is used to transmit the UL data, a DL period, which is used to transmit the retransmission command information, and a guard period, which is used to switch between the UL period and the DL period. 
     
     
         5 . The user terminal according to  claim 1 , wherein:
 a default retransmission command is defined with either an ACK or a NACK; and   when the retransmission command information indicates a retransmission command that is different from the default retransmission command, the retransmission command information is transmitted to the user terminal.   
     
     
         6 . A radio communication method in a user terminal, comprising the steps of:
 transmitting uplink (UL) data; and   controlling retransmission of the UL data based on retransmission command information, which provides a retransmission command for the UL data by a frequency resource, or by a resource group, which includes the frequency resource.   
     
     
         7 . The user terminal according to  claim 2 , wherein the retransmission command information is transmitted to the user terminal by using a dedicated resource, which is specific to the frequency resource or the resource group, or by using a common resource, which is common to the frequency resource or the resource group. 
     
     
         8 . The user terminal according to  claim 2 , wherein a transmission time interval (TTI), in which the UL data is transmitted, is comprised of a UL period, which is used to transmit the UL data, a DL period, which is used to transmit the retransmission command information, and a guard period, which is used to switch between the UL period and the DL period. 
     
     
         9 . The user terminal according to  claim 3 , wherein a transmission time interval (TTI), in which the UL data is transmitted, is comprised of a UL period, which is used to transmit the UL data, a DL period, which is used to transmit the retransmission command information, and a guard period, which is used to switch between the UL period and the DL period. 
     
     
         10 . The user terminal according to  claim 7 , wherein a transmission time interval (TTI), in which the UL data is transmitted, is comprised of a UL period, which is used to transmit the UL data, a DL period, which is used to transmit the retransmission command information, and a guard period, which is used to switch between the UL period and the DL period. 
     
     
         11 . The user terminal according to  claim 2 , wherein:
 a default retransmission command is defined with either an ACK or a NACK; and   when the retransmission command information indicates a retransmission command that is different from the default retransmission command, the retransmission command information is transmitted to the user terminal.   
     
     
         12 . The user terminal according to  claim 3 , wherein:
 a default retransmission command is defined with either an ACK or a NACK; and   when the retransmission command information indicates a retransmission command that is different from the default retransmission command, the retransmission command information is transmitted to the user terminal.   
     
     
         13 . The user terminal according to  claim 4 , wherein:
 a default retransmission command is defined with either an ACK or a NACK; and   when the retransmission command information indicates a retransmission command that is different from the default retransmission command, the retransmission command information is transmitted to the user terminal.   
     
     
         14 . The user terminal according to  claim 7 , wherein:
 a default retransmission command is defined with either an ACK or a NACK; and   when the retransmission command information indicates a retransmission command that is different from the default retransmission command, the retransmission command information is transmitted to the user terminal.   
     
     
         15 . The user terminal according to  claim 8 , wherein:
 a default retransmission command is defined with either an ACK or a NACK; and   when the retransmission command information indicates a retransmission command that is different from the default retransmission command, the retransmission command information is transmitted to the user terminal.   
     
     
         16 . The user terminal according to  claim 9 , wherein:
 a default retransmission command is defined with either an ACK or a NACK; and   when the retransmission command information indicates a retransmission command that is different from the default retransmission command, the retransmission command information is transmitted to the user terminal.