Data packet delivery in RRC inactive state

1. A method performed by a User Equipment (UE) for wireless communication, the method comprising:

initiating, by the UE, a random access (RA) procedure for transmitting data to a base station based on comparing an amount of the data with a first threshold configured to the UE;

transmitting, by the UE in a Radio Resource Control (RRC) Inactive (RRC_Inactive) state, at least one packet of the data to the base station using the RA procedure;

receiving, by the UE in the RRC_Inactive state, an acknowledgement or non-acknowledgement (ACK/NACK) message from the base station in response to the at least one packet transmitted by the UE; and

initiating, by the UE, an RRC Resume procedure to transition from the RRC_Inactive state to an RRC Connected (RRC_Connected) state and transmit pending packets of the data in the RRC_Connected state when at least one of (i) the amount of the data is higher than a second threshold configured to the UE and (ii) the pending packets are not transmittable using the RA procedure, wherein the UE initiates the RRC Resume procedure without receiving an instruction from the base station to initiate the RRC Resume procedure.

2. The method of claim 1 , wherein the ACK/NACK message includes an instruction to the UE to stay in the RRC_Inactive state.

3. The method of claim 1 , further comprising:

transmitting, by the UE, a random access preamble to the base station,

wherein the random access preamble is associated with random access resources including time and/or frequency radio resources that are reserved for a plurality of UEs by the base station for data transmission.

4. The method of claim 1 , further comprising:

providing, by the UE, capability information to the base station, the capability information indicating whether the UE supports operations in the RRC_Inactive state.

5. The method of claim 1 , further comprising:

receiving, by the UE, a pre-configured random access configuration in an RRC configuration message; and

applying, by the UE, the pre-configured random access configuration in the random access procedure to transmit the at least one packet to the base station,

wherein the pre-configured random access configuration comprises at least one of a pre-configured bandwidth part (BWP) configuration, a plurality of access control parameters, a UE identifier (ID), and a time pattern of random access.

6. The method of claim 5 , wherein one of the plurality of access control parameters comprises a parameter indicating the amount of the data.

7. The method of claim 1 , wherein the at least one packet includes an indicator indicating whether a second packet is pending for transmission from the UE to the base station.

8. The method of claim 7 , further comprising:

receiving, by the UE, information of additional uplink grant resources in the ACK/NACK message when the indicator indicates that the second packet is pending for transmission from the UE to the base station,

wherein the base station allocates the additional uplink grant resources to the UE for transmitting the second packet.

9. The method of claim 1 , further comprising:

receiving the data through a set of one or more logical channels that are enabled for data transmission in the RRC_Inactive state, wherein the amount of the data is calculated based on the received data through the set of one or more logical channels.

10. The method of claim 1 , wherein the RA procedure is initiated when the amount of the data is higher than the first threshold configured to the UE.

11. A user equipment (UE) for wireless communication, the UE comprising:

one or more non-transitory computer-readable media having computer-executable instructions embodied thereon; and

at least one processor coupled to the one or more non-transitory computer-readable media, and configured to execute the computer-executable instructions to:

initiate, by the UE, a random access (RA) procedure for transmitting data to a base station based on comparing an amount of the data with a first threshold configured to the UE;

transmit, in a Radio Resource Control (RRC) Inactive (RRC_Inactive) state, at least one packet of the data to the base station using the RA procedure;

receive, in the RRC_Inactive state, an acknowledgement or non-acknowledgement (ACK/NACK) message from the base station in response to the at least one packet transmitted by the UE; and

initiate, by the UE, an RRC Resume procedure to transition from the RRC_Inactive state to an RRC Connected (RRC_Connected) state and transmit pending packets of the data in the RRC Connected state when at least one of (i) the amount of the data is higher than a second threshold configured to the UE and (ii) the pending packets are not transmittable using the RA procedure, wherein the UE initiates the RRC Resume procedure without receiving an instruction from the base station to initiate the RRC Resume procedure.

12. The UE of claim 11 , wherein the ACK/NACK message includes an instruction to the UE to stay in the RRC_Inactive state.

13. The UE of claim 11 , wherein the at least one processor is further configured to execute the computer-executable instructions to:

transmit a random access preamble to the base station,

wherein the random access preamble is associated with random access resources including time and/or frequency radio resources that are reserved for a plurality of UEs by the base station for data transmission.

14. The UE of claim 11 , wherein the at least one processor is further configured to execute the computer-executable instructions to:

provide capability information to the base station, the capability information indicating whether the UE supports operations in the RRC_Inactive state.

15. The UE of claim 11 , wherein the at least one processor is further configured to execute the computer-executable instructions to:

receive a pre-configured random access configuration in an RRC configuration message; and

apply the pre-configured random access configuration in the random access procedure to transmit the at least one packet to the base station,

wherein the pre-configured random access configuration comprises at least one of a pre-configured bandwidth part (BWP) configuration, a plurality of access control parameters, a UE identifier (ID), and a time pattern of random access.

16. The UE of claim 15 , wherein one of the plurality of access control parameters comprises a parameter indicating the amount of the data.

17. The UE of claim 11 , wherein the at least one packet includes an indicator indicating whether a second packet is pending for transmission from the UE to the base station.

18. The UE of claim 17 , wherein the at least one processor is further configured to execute the computer-executable instructions to:

receive information of additional uplink grant resources in the ACK/NACK message when the indicator indicates that the second packet is pending for transmission from the UE to the base station,

wherein the base station allocates the additional uplink grant resources to the UE for transmitting the second packet.

19. The UE of claim 11 , wherein the at least one processor is further configured to execute the computer-executable instructions to:

receive the data through one or more of a plurality of logical channels, wherein the one or more of the plurality of logical channels are only enabled for data transmission in the RRC_Inactive state.

20. The UE of claim 11 , wherein the at least one processor is further configured to execute the computer-executable instructions to:

initiate the RA procedure when the amount of the data is higher than the first threshold configured to the UE.