User terminal and radio communication method

A radio communication method for a terminal, comprising:

• determining, based on higher layer signaling indicating transmission of message A including a random access preamble, whether or not to apply a 2-step contention-free random access procedure;
• when the 2-step contention-free random access procedure is applied, transmitting the message A;
• and
• receiving, as a response to the message A, message B including a downlink control channel received in a common search space set, during a given period after transmission of the message A,
• wherein when the terminal does not correctly receive the message B during the given period, the terminal transmits hybrid automatic repeat request acknowledgement (HARQ-ACK) with a negative acknowledgement (NACK) value and receives retransmission of the message B, and
• wherein cyclic redundancy check (CRC) of downlink control information on the downlink control channel is scrambled by an identifier included in the message A.

A base station comprising:

• a processor that indicates, by using higher layer signaling indicating transmission of message A including a random access preamble, whether or not to apply a 2-step contention-free random access procedure;
• a receiver that, when the 2-step contention-free random access procedure is applied, receives the message A;
• and
• a transmitter that transmits, as a response to the message A, message B including a downlink control channel received in a common search space set, during a given period after reception of the message A,
• wherein when a terminal does not correctly receive the message B during the given period, the receiver receives hybrid automatic repeat request acknowledgement (HARQ-ACK) with a negative acknowledgement (NACK) value, and the transmitter performs retransmission of the message B, and
• wherein cyclic redundancy check (CRC) of downlink control information on the downlink control channel is scrambled by an identifier included in the message A.

A system comprising a terminal and a base station, wherein

• the terminal comprises:
• a processor that determines, based on higher layer signaling indicating transmission of message A including a random access preamble, whether or not to apply a 2-step contention-free random access procedure;
• a transmitter that, when the 2-step contention-free random access procedure is applied, transmits the message A;
• and
• a receiver that receives, as a response to the message A, message B including a downlink control channel received in a common search space set, during a given period after transmission of the message A, and
• the base station comprises:
• a receiver that receives the message A;
• and
• a transmitter that transmits the message B,
• wherein when the receiver of the terminal does not correctly receive the message B during the given period, the transmitter of the terminal transmits hybrid automatic repeat request acknowledgement (HARQ-ACK) with a negative acknowledgement (NACK) value, and the receiver of the terminal receives retransmission of the message B, and
• wherein cyclic redundancy check (CRC) of downlink control information on the downlink control channel is scrambled by an identifier included in the message A.