Apparatus and method for performing random access in wireless communication system

1. A method comprising:

transmitting, by a wireless device to a base station, a first random access preamble;

determining, based on a transmission time point associated with the first random access preamble, a time window for monitoring for a random access response;

receiving, during the time window, a first random access response;

determining, based on receiving the first random access response, transmission of a second random access preamble, wherein a time for preparing for the transmission of the second random access preamble is set based on one of:

a first subcarrier spacing associated with the first random access preamble; or

a second subcarrier spacing associated with the first random access response; and

transmitting, based on the preparing, the second random access preamble.

2. The method of claim 1 , further comprising:

determining a supplementary uplink cell in which the first random access preamble is to be transmitted,

wherein the first subcarrier spacing is associated with the supplementary uplink cell and is different from the second subcarrier spacing, and

wherein the second subcarrier spacing is associated with a downlink carrier via which the first random access response is received.

3. The method of claim 2 , wherein the supplementary uplink cell comprises an uplink carrier that supplements a different uplink carrier for the wireless device.

4. The method of claim 1 , wherein the first subcarrier spacing comprises a subcarrier spacing of an uplink bandwidth part via which the first random access preamble is transmitted.

5. The method of claim 1 , wherein the second subcarrier spacing comprises a subcarrier spacing associated with a slot in which the first random access response is received.

6. The method of claim 1 , further comprising:

determining that the first random access response lacks information responsive to the first random access preamble; and

determining, based on the first random access response lacking the information responsive to the first random access preamble, the transmission of the second random access preamble.

7. The method of claim 1 , further comprising:

determining the reception of the first random access response, based on:

a downlink control channel scrambled by a random access radio network temporary identifier; and

a downlink shared channel associated with the downlink control channel.

8. The method of claim 1 , further comprising:

determining, based on the one of the first subcarrier spacing or the second subcarrier spacing, a timing requirement for completing the preparing.

9. The method of claim 8 , wherein the timing requirement is further based on a reception time of the first random access response.

10. The method of claim 8 , wherein the timing requirement is further based on a quantity of symbols associated with a configuration of an additional demodulation reference signal (DMRS).

11. The method of claim 1 , wherein transmitting the second random access preamble comprises transmitting, within a time period that starts from a reception time of the first random access response, the second random access preamble,

wherein the time period that starts from the reception time of the first random access response is based on one of:

the first subcarrier spacing associated with the first random access preamble; or

the second subcarrier spacing associated with the first random access response.

12. A method comprising:

transmitting, by a wireless device to a base station, a first random access preamble;

determining, based on a transmission time point associated with the first random access preamble, a time window for monitoring for a random access response;

determining that the random access response has not been detected during the time window;

determining, based on an expiration of the time window, a transmission of a second random access preamble, wherein a time for preparing for the transmission of the second random access preamble is set based on one of:

a first subcarrier spacing associated with the first random access preamble; or

a second subcarrier spacing associated with a downlink channel scheduled for the random access response; and

transmitting, based on the preparing, the second random access preamble.

13. The method of claim 12 , further comprising:

determining a supplementary uplink cell via which the first random access preamble is to be transmitted,

wherein the first subcarrier spacing is associated with the supplementary uplink cell and is different from the second subcarrier spacing.

14. The method of claim 12 , wherein the first subcarrier spacing comprises a subcarrier spacing of an uplink bandwidth part via which the first random access preamble is transmitted.

15. The method of claim 12 , further comprising:

determining, based on the one of the first subcarrier spacing or the second subcarrier spacing, a timing requirement for completing the preparing.

16. The method of claim 15 , wherein the timing requirement is further based on an expiration time of the time window.

17. The method of claim 12 , wherein transmitting the second random access preamble comprises transmitting, within a time period that starts from an expiration time of the time window, the second random access preamble,

wherein the time period that starts from the expiration time of the time window is based on one of:

the first subcarrier spacing associated with the first random access preamble; or

the second subcarrier spacing associated with the downlink channel scheduled for the random access response.

18. A method comprising:

transmitting, by a wireless device to a base station, a first random access preamble;

determining, based on the transmitting the first random access preamble, a time window for monitoring for a random access response;

determining that the random access response has not been detected during the time window;

determining, based on an expiration of the time window, a transmission of a second random access preamble, wherein a time for preparing for the transmission of the second random access preamble is based on one of:

a first subcarrier spacing associated with an uplink channel; or

a second subcarrier spacing associated with a downlink channel; and

transmitting, based on the preparing, the second random access preamble.

19. The method of claim 18 , wherein the uplink channel is associated with the first random access preamble, and

wherein the downlink channel comprises a downlink channel scheduled for the random access response.

20. The method of claim 18 , further comprising:

determining a supplementary uplink cell via which the first random access preamble is to be transmitted,

wherein the first subcarrier spacing is associated with the supplementary uplink cell and is different from the second subcarrier spacing.

21. The method of claim 18 , wherein the first subcarrier spacing comprises a subcarrier spacing of an uplink bandwidth part via which the first random access preamble is transmitted.

22. The method of claim 18 , further comprising:

determining, based on the one of the first subcarrier spacing or the second subcarrier spacing, a timing requirement for completing the preparing.

23. The method of claim 18 , further comprising determining, based on the first subcarrier spacing, the time for preparing for the transmission of the second random access preamble,

wherein the first subcarrier spacing is narrower than the second subcarrier spacing.

24. The method of claim 18 , further comprising determining, based on the second subcarrier spacing, the time for preparing for the transmission of the second random access preamble,

wherein the second subcarrier spacing is narrower than the first subcarrier spacing.