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

1. A terminal apparatus comprising:

reception circuitry configured to:

receive first information for identifying one or multiple random access channel occasions, and

receive second information for identifying an index of a random access preamble; and

selection circuitry configured to:

in a case that a first condition is satisfied, select, from one or multiple reference signals, a first reference signal based on a measurement of each of the one or multiple reference signals,

in a case that a second condition is satisfied, select a second reference signal associated with a physical downlink control channel used to receive the second information, and

select, from the one or multiple random access channel occasions, one random access channel occasion associated with the selected first or second reference signal,

wherein the first condition includes a case that the second information is received through a Radio Resource Control (RRC) message, and the second condition includes a case that the second information is received on the physical downlink control channel.

2. The terminal apparatus according to claim 1 , wherein:

the first condition further includes a condition that the index of the random access preamble indicated by the second information has a first value that is predetermined, and

the second condition further includes a condition that the index of the random access preamble indicated by the second information does not have the first value.

3. A base station apparatus for communicating with a terminal apparatus, the base station apparatus comprising:

transmission circuitry configured to:

transmit, to the terminal apparatus, one or multiple reference signals,

transmit, to the terminal apparatus, first information for identifying one or multiple random access channel occasions, and

transmit, to the terminal apparatus, second information for identifying an index of a random access preamble; and

monitoring circuitry configured to:

in a case that a first condition is satisfied, monitor the random access preamble transmitted from the terminal apparatus in a random access channel occasion of the one or multiple random access channel occasions assigned for each of the one or multiple reference signals, and

in a case that a second condition is satisfied, monitor the random access preamble transmitted from the terminal apparatus in the random access channel occasion assigned for one of the one or multiple reference signals associated with a physical downlink control channel used to transmit the second information,

wherein the first condition includes a case that the second information is transmitted through a Radio Resource Control (RRC) message, and the second condition includes a case that the second information is transmitted on the physical downlink control channel.

4. A communication method used for a terminal apparatus, the communication method comprising:

receiving first information for identifying one or multiple random access channel occasions;

receiving second information for identifying an index of a random access preamble;

in a case that a first condition is satisfied, selecting, from one or multiple reference signals, a first reference signal based on a measurement of each of the one or multiple reference signals;

in a case that a second condition is satisfied, selecting a second reference signal signals associated with a physical downlink control channel used to receive the second information; and

selecting, from the one or multiple random access channel occasions, one random access channel occasion associated with the selected first or second reference signal,

wherein the first condition includes a case that the second information is received through a Radio Resource Control (RRC) message, and the second condition includes a case that the second information is received on the physical downlink control channel.

5. A communication method used for a base station apparatus, the communication method comprising:

transmitting, to the terminal apparatus, one or multiple reference signals;

transmitting, to the terminal apparatus, first information for identifying one or multiple random access channel occasions;

transmitting, to the terminal apparatus, second information for identifying an index of a random access preamble;

in a case that a first condition is satisfied, monitoring the random access preamble transmitted from the terminal apparatus in a random access channel occasion of the one or multiple random access channel occasions assigned for each of the one or multiple reference signals; and

in a case that a second condition is satisfied, monitoring the random access preamble transmitted from the terminal apparatus in the random access channel occasion assigned for one of the one or multiple reference signals associated with a physical downlink control channel used to transmit the second information,

wherein the first condition includes a case that the second information is transmitted through a Radio Resource Control (RRC) message, and the second condition includes a case that the second information is transmitted on the physical downlink control channel.

6. A terminal apparatus, comprising:

an integrated circuit configured to:

receive first information for identifying one or multiple random access channel occasions;

receive second information for identifying an index of a random access preamble;

in a case that a first condition is satisfied, select, from one or multiple reference signals, a first reference signal based on a measurement of each of the one or multiple reference signals;

in a case that a second condition is satisfied, select a second reference signal associated with a physical downlink control channel used to receive the second information; and

select, from the one or multiple random access channel occasions, one random access channel occasion associated with the selected first or second reference signal,

wherein the first condition includes a case that the second information is received through a Radio Resource Control (RRC) message, and the second condition includes a case that the second information is received on the physical downlink control channel.

7. A base station apparatus, comprising:

an integrated circuit configured to:

transmit, to the terminal apparatus, one or multiple reference signals;

transmit, to the terminal apparatus, first information for identifying one or multiple random access channel occasions;

transmit, to the terminal apparatus, second information for identifying an index of a random access preamble;

in a case that a first condition is satisfied, monitor the random access preamble transmitted from the terminal apparatus in a random access channel occasion of the one or multiple random access channel occasions assigned for each of the one or multiple reference signals; and

in a case that a second condition is satisfied, monitor the random access preamble transmitted from the terminal apparatus in the random access channel occasion assigned for one of the one or multiple reference signals associated with a physical downlink control channel used to transmit the second information,

wherein the first condition includes a case that the second information is transmitted through a Radio Resource Control (RRC) message, and the second condition includes a case that the second information is transmitted on the physical downlink control channel.