User equipment and method for small data transmission
A user equipment (UE) and a method for small data transmission (SDT) are provided. The method includes initiating an SDT procedure while the UE is in a Radio Resource Control (RRC) Inactive (RRC_INACTIVE) state; initiating a random access (RA) procedure before the SDT procedure is terminated; and determining whether to include a Cell-Radio Network Temporary Identifier (C-RNTI) Medium Access Control (MAC) Control Element (CE) in an uplink (UL) message during the RA procedure based on at least one condition. The at least one condition includes whether the SDT procedure corresponds to a Configured Grant (CG)-SDT procedure. The UL message is a message 3 (Msg3) in a case that the RA procedure is a 4-step RA procedure. The UL message is a message A (MsgA) in a case that the RA procedure is a 2-step RA procedure.
1 . A method performed by a user equipment (UE) for small data transmission (SDT), the method comprising:
initiating an SDT procedure while the UE is in a Radio Resource Control (RRC) Inactive (RRC_INACTIVE) state;
initiating a random access (RA) procedure due to data arrival at a common control channel (CCCH), wherein the RA procedure is initiated before the SDT procedure is terminated; and
including a Cell-Radio Network Temporary Identifier (C-RNTI) Medium Access Control (MAC) Control Element (CE) in an uplink (UL) message during the RA procedure in response to determining that the UE has a valid C-RNTI before initiating the RA procedure, wherein:
determining that the UE has a valid C-RNTI comprises determining that the UE has the valid C-RNTI in response to determining that the UE has not discarded the valid C-RNTI,
the UL message is a message 3 (Msg3) in a case that the RA procedure is a 4-step RA procedure, and
the UL message is a message A (MsgA) in a case that the RA procedure is a 2-step RA procedure.
2 . The method of claim 1 , wherein the UE discards the valid C-RNTI in response to determining that a specific timer has expired.
3 . The method of claim 1 , wherein the UE discards the valid C-RNTI in response to receiving a core network (CN) paging message indicating a state transitioning from the RRC_INACTIVE state to an RRC_IDLE state.
4 . The method of claim 1 , further comprising forgoing including the C-RNTI MAC CE in the UL message in response to determining that the UE has not discarded the valid C-RNTI before initiating the RA procedure.
5 . The method of claim 4 , wherein the CCCH data is included in the UL message when the C-RNTI MAC CE is not included in the UL message.
6 . The method of claim 1 , wherein the UE discards the valid C-RNTI in response to detecting an SDT failure.
7 . The method of claim 1 , wherein the UE discards the valid C-RNTI in response to receiving, from a base station, an indication to discard the valid C-RNTI.
8 . The method of claim 1 , wherein the CCCH data is not allowed to be included in the UL message in response to including the C-RNTI MAC CE in the UL message.
9 . A user equipment (UE) for small data transmission (SDT), the UE comprising:
at least one processor; and
at least one non-transitory computer-readable medium coupled to the at least one processor and storing one or more computer-executable instructions that, when executed by the at least one processor, cause the UE to:
initiate an SDT procedure while the UE is in a Radio Resource Control (RRC) Inactive (RRC_INACTIVE) state;
initiate a random access (RA) procedure due to data arrival at a common control channel (CCCH), wherein the RA procedure is initiated before the SDT procedure is terminated; and
include a Cell-Radio Network Temporary Identifier (C-RNTI) Medium Access Control (MAC) Control Element (CE) in an uplink (UL) message during the RA procedure in response to determining that the UE has a valid C-RNTI before initiating the RA procedure, wherein:
determining that the UE has a valid C-RNTI comprises determining that the UE has the valid C-RNTI in response to determining that the UE has not discarded the valid C-RNTI,
the UL message is a message 3 (Msg3) in a case that the RA procedure is a 4-step RA procedure, and
the UL message is a message A (MsgA) in a case that the RA procedure is a 2-step RA procedure.
10 . The UE of claim 9 , wherein the UE discards the valid C-RNTI in response to determining that a specific timer has expired.
11 . The UE of claim 9 , wherein the UE discards the valid C-RNTI in response to receiving a core network (CN) paging message indicating a state transitioning from the RRC_INACTIVE state to an RRC_IDLE state.
12 . The UE of claim 9 , further comprising forgoing including the C-RNTI MAC CE in the UL message in response to determining that the UE has not discarded the valid C-RNTI before initiating the RA procedure.
13 . The UE of claim 12 , wherein the CCCH data is included in the UL message when the C-RNTI MAC CE is not included in the UL message.
14 . The UE of claim 9 , wherein the UE discards the valid C-RNTI in response to detecting an SDT failure.
15 . The UE of claim 9 , wherein the UE discards the valid C-RNTI in response to receiving, from a base station, an indication to discard the valid C-RNTI.
16 . The UE of claim 9 , wherein the CCCH data is not allowed to be included in the UL message in response to including the C-RNTI MAC CE in the UL message.