METHOD AND APPARATUS USING MULTIPLE PREAMBLES IN RANDOM ACCESS

1 .- 11 . (canceled)

12 . A method for a user equipment (UE) performing random access (RA) in a RA occasion, the method comprising:

determining a number K 1 of time-frequency resources comprising at least a first time-frequency resource through a K 1 th time-frequency resource that do not overlap in a time domain;

sending, to a network, a first preamble using at least the first time-frequency resource;

starting a first time window beginning at a first moment; and

monitoring for a first signaling, from the network, in the first time window, wherein the first signaling is used for scheduling a random access response (RAR), wherein the first moment is not earlier than a cut-off moment of the first time-frequency resource and is earlier than a cut-off moment of the K1th time-frequency resource, and wherein an expiration moment of the first time window is later than a cut-off moment of the K 1 th time-frequency resource.

13 . The method of claim 12 , wherein the first signaling in the first time window is used for determining whether to send a second preamble using at least the K 1 th time-frequency resource.

14 . The method of claim 13 , further comprising:

receiving the first signaling; and

receiving a first RAR according to the scheduling of the first signaling.

15 . The method of claim 14 , further comprising:

determining, based on the first RAR, whether to send the second preamble using at least the K 1 th time-frequency resource.

16 . The method of claim 15 , wherein the determined K 1 time-frequency resources are respectively associated with K 1 downlink reference signal (RS) resources, and the method further comprises:

sending, to the network in response to the first RAR being received in the first time window, a message associated with a target downlink RS resource of the K 1 downlink RS resources, wherein the target downlink RS resource is determined from a control resource set (CORESET) or search space of the first signaling.

17 . The method of claim 12 , further comprising:

determining that the expiration moment of the first time window has occurred; and

in response to the expiration moment of the first time window occurring, updating a first counter according to a next time-frequency resource of the K 1 time-frequency resources, wherein the first counter is configured to track a number of preambles sent in the RA occasion.

18 . The method of claim 17 , further comprising:

restarting the first time window at a second moment related to a cut-off moment of the next time-frequency resource; and

sending, to the network, a second preamble using the next time-frequency resource.

19 . The method of claim 18 , wherein the next time-frequency resource is used for determining an updated expiration moment of the restarted first time window.

20 . A user equipment (UE) configured to perform random access (RA) in a RA occasion, the UE comprising:

a processor, a transmitter, a receiver and a processor operatively coupled to the transmitter and the receiver, wherein the transmitter, receiver and processor are configured to:

determine a number K 1 of time-frequency resources comprising at least a first time-frequency resource through a K 1 th time-frequency resource that do not overlap in a time domain;

send, to a network, a first preamble using at least the first time-frequency resource;

start a first time window beginning at a first moment; and

monitor for a first signaling, from the network, in the first time window, wherein the first signaling is used for scheduling a random access response (RAR), wherein the first moment is not earlier than a cut-off moment of the first time-frequency resource and is earlier than a cut-off moment of the K 1 th time-frequency resource, and wherein an expiration moment of the first time window is later than a cut-off moment of the K 1 th time-frequency resource.

21 . The UE of claim 20 , wherein the first signaling in the first time window is used for determining whether to send a second preamble using at least the K 1 th time-frequency resource.

22 . The UE of claim 21 , wherein the receiver and the processor are further configured to:

receive the first signaling; and

receive a first RAR according to the scheduling of the first signaling.

23 . The UE of claim 22 , wherein the processor is further configured to:

determine, based on the first RAR, whether to send the second preamble using at least the K 1 th time-frequency resource.

24 . The UE of claim 23 , wherein the determined K 1 time-frequency resources are respectively associated with K 1 downlink reference signal (RS) resources, and wherein the processor and the transmitter are further configured to:

send, to the network in response to the first RAR being received in the first time window, a message associated with a target downlink RS resource of the K 1 downlink RS resources, wherein the target downlink RS resource is determined from a control resource set (CORESET) or search space of the first signaling.

25 . The UE of claim 20 , wherein the processor is further configured to:

determine that the expiration moment of the first time window has occurred; and

in response to the expiration moment of the first time window occurring, update a first counter according to a next time-frequency resource of the K 1 time-frequency resources, wherein the first counter is configured to track a number of preambles sent in the RA occasion.

26 . The UE of claim 25 , wherein the processor and the transmitter are further configured to:

restart the first time window at a second moment related to a cut-off moment of the next time-frequency resource; and

send, to the network, a second preamble using the next time-frequency resource.

27 . The UE of claim 26 , wherein the next time-frequency resource is used for determining an updated expiration moment of the restarted first time window.