Terminal, radio communication method, base station, and system

Abstract

A terminal is disclosed including a processor that, if retransmission of an uplink shared channel is performed, determines a time density of a phase tracking reference signal (PTRS) based on whether a modulation and coding scheme (MCS) index is larger than a certain value; and a transmitter that transmits the PTRS. In other aspects, a radio communication method, a base station, and a system are also disclosed.

1 .- 3 . (canceled) 
     
     
         4 . A terminal comprising:
 a processor that, if retransmission of an uplink shared channel is performed, determines a time density of a phase tracking reference signal (PTRS) based on whether a modulation and coding scheme (MCS) index is larger than a certain value; and   a transmitter that transmits the PTRS.   
     
     
         5 . The terminal according to  claim 4 , wherein if the MCS index is larger than the certain value, the processor determines the time density of the PTRS based on the MCS index, notified in an initial transmission, that is smaller than or equal to the certain value. 
     
     
         6 . The terminal according to  claim 4 , wherein the time density of the PTRS is determined according to an MCS index threshold indicated in a higher layer. 
     
     
         7 . A radio communication method comprising:
 if retransmission of an uplink shared channel is performed, determining a time density of a phase tracking reference signal (PTRS) based on whether a modulation and coding scheme (MCS) index is larger than a certain value; and   transmitting the PTRS.   
     
     
         8 . A base station comprising:
 a processor that controls retransmission of an uplink shared channel; and   a receiver that, if the retransmission of the uplink shared channel is performed, receives a phase tracking reference signal (PTRS) whose time density is determined based on whether a modulation and coding scheme (MCS) index is larger than a certain value.   
     
     
         9 . The terminal according to  claim 5 , wherein the time density of the PTRS is determined according to an MCS index threshold indicated in a higher layer. 
     
     
         10 . A system comprising a terminal and a base station, wherein
 the terminal comprises:
 a processor of the terminal that, if retransmission of an uplink shared channel is performed, determines a time density of a phase tracking reference signal (PTRS) based on whether a modulation and coding scheme (MCS) index is larger than a certain value; and 
 a transmitter that transmits the PTRS, 
   the base station comprises:
 a processor of the base station that controls the retransmission of an uplink shared channel; and 
 a receiver that, if the retransmission of the uplink shared channel is performed, receives the PTRS whose time density is determined based on whether the MCS index is larger than the certain value.