Small data transmission in radio resource control (RRC) inactive state
Some of the present implementations provide a method for a user equipment (UE) for transmitting uplink (UL) data associated with a specific radio bearer (RB). The UE receives, while in a radio resource control (RRC)_CONNECTED state, from a base station (BS), an RRC release message that includes at least a configured grant (CG) configuration and a time alignment (TA) timer. The UE then transitions to an RRC_INACTIVE state and starts, or restarts, the TA timer in response to receiving the RRC release message. The UE transmits, while in the RRC_INACTIVE state, the UL data via a UL resource configured by the CG configuration after determining that a set of one or more criteria is met, the set of criteria including at least a criterion for the TA timer being running.
1. A method for a user equipment (UE) for transmitting uplink (UL) data associated with a specific radio bearer (RB), the method comprising:
receiving, while in a radio resource control (RRC) Connected state, from a base station (BS), an RRC release message that includes at least a configured grant (CG) configuration and a time alignment (TA) timer;
transitioning to an RRC Inactive state in response to receiving the RRC release message;
starting or restarting the TA timer in response to receiving the RRC release message; and
transmitting, while in the RRC Inactive state, the UL data via a UL resource on a physical uplink shared channel (PUSCH) configured by the CG configuration after determining that a set of one or more criteria is met, the set of one or more criteria including at least a criterion for the TA timer being running.
2. The method of claim 1 , further comprising:
starting or restarting the TA timer further in response to receiving, from the BS, while in the RRC Inactive state, an indication to update timing advance.
3. The method of claim 1 , further comprising:
initiating a random access (RA) procedure when determining that one of the set of one or more criteria is not met.
4. The method of claim 1 , wherein the set of one or more criteria further includes a criterion for a data volume of the UL data being lower than a threshold.
5. The method of claim 4 , further comprising:
initiating an RRC connection resume procedure when the data volume of the UL data is above the threshold.
6. The method of claim 5 , wherein the data volume is determined based on a total amount of the UL data associated with the specific RB.
7. The method of claim 1 , wherein the set of one or more criteria further includes a criterion for a synchronization signal block (SSB) with reference signal received power (RSRP) being above a threshold.
8. The method of claim 1 , wherein the set of one or more criteria further includes a criterion for a specific timer being running, the specific timer being started or restarted when the UE transmits the UL data via the UL resource.
9. The method of claim 1 , wherein the specific RB is configured for small data transmission.
10. The method of claim 1 , wherein the RRC release message further includes a suspendConfig information element (IE).
11. A user equipment (UE), comprising:
one or more non-transitory computer-readable media having computer-executable instructions for transmitting uplink (UL) data associated with a specific radio bearer (RB); 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:
receive, while in a radio resource control (RRC) Connected state, from a base station (BS), an RRC release message that includes at least a configured grant (CG) configuration and a time alignment (TA) timer;
transition to an RRC Inactive state in response to receiving the RRC release message;
start the TA timer in response to receiving the RRC release message; and
transmit, while in the RRC Inactive state, the UL data via a UL resource on a physical uplink shared channel (PUSCH) configured by the CG configuration after determining that a set of one or more criteria is met, the set of one or more criteria including at least a criterion for the TA timer being running.
12. The UE of claim 11 , wherein at the least one processor is further configured to execute the computer-executable instructions to:
start or restart the TA timer further in response to receiving, from the BS, while in the RRC Inactive state, an indication to update timing advance.
13. The UE of claim 11 , wherein at the least one processor is further configured to execute the computer-executable instructions to:
initiate a random access (RA) procedure when determining that one of the set of one or more criteria is not met.
14. The UE of claim 11 , wherein the set of one or more criteria further includes a criterion for a data volume of the UL data being lower than a threshold.
15. The UE of claim 14 , wherein at the least one processor is further configured to execute the computer-executable instructions to:
initiate an RRC connection resume procedure when the data volume of the UL data is above the threshold.
16. The UE of claim 15 , wherein the data volume is determined based on a total amount of the UL data associated with the specific RB.
17. The UE of claim 11 , wherein the set of one or more criteria further includes a criterion for a synchronization signal block (SSB) with reference signal received power (RSRP) being above a threshold.
18. The UE of claim 11 , wherein the set of one or more criteria further includes a criterion for a specific timer being running, the specific timer being started or restarted when the UE transmits the UL data via the UL resource.
19. The UE of claim 11 , wherein the specific RB is configured for small data transmission.
20. The UE of claim 11 , wherein the RRC release message further includes a suspendConfig information element (IE).