US-12621898-B2 - Method and device for transmitting small data in wireless communication system

Abstract

The present disclosure may provide a method of transmitting, by a user equipment (UE), small data in a wireless communication system. Here, a small data transmission method may include enabling a small data configuration in a UE; triggering, by the UE, a small data transmission; transmitting, by the UE, a common control channel (CCCH) and buffered data information to a base station in a random access channel (RACH) procedure; receiving a random access response (RAR) including an uplink (UL) grant from the base station based on the buffered data information; and transmitting the small data based on the UL grant.

Inventors

• Won Seok Lee
• Dong Hyun Park
• Ki Bum Kwon

Assignees

• Innovative Technology Lab Co., Ltd.

Dates

Publication Date

20260505

Application Date

20221213

Priority Date

20200615

Claims (17)

1. 1 . A method comprising: receiving, by a wireless user device, system information indicating a plurality of physical random access channel (PRACH) configurations comprising a first PRACH configuration for small data transmission and a second PRACH configuration for small data transmission, wherein the first PRACH configuration comprises a plurality of random access channel (RACH) resources for small data transmission associated with a radio resource control (RRC) inactive state; receiving, by the wireless user device in an RRC connected state, an RRC release message; transitioning, by the wireless user device and based on the RRC release message, from the RRC connected state to the RRC inactive state; transmitting, by the wireless user device in the RRC inactive state to a base station, a message A (MsgA) for a 2-step RACH procedure, wherein the MsgA comprises a preamble and MsgA physical uplink shared channel (MsgA PUSCH), wherein the MsgA PUSCH comprises a buffer status report medium access control control element (BSR MAC CE), and wherein the BSR MAC CE indicates a data size; receiving, by the wireless user device in the RRC inactive state, a fallback random access response (RAR) comprising an uplink (UL) grant; and based on the UL grant, transmitting, by the wireless user device in the RRC inactive state, a message 3 (Msg3) to the base station via a selected RACH resource for 4-step RACH procedure, wherein the Msg3 comprises common control channel (CCCH) data and small data, wherein the first PRACH configuration comprises a first preamble group for 4-step RACH procedure, a second preamble group for 4-step RACH procedure, a third preamble group for 2-step RACH procedure, and a fourth preamble group for 2-step RACH procedure, and wherein the second PRACH configuration comprises a fifth preamble group for 4-step RACH procedure, a sixth preamble group for 4-step RACH procedure, a seventh preamble group for 2-step RACH procedure, and an eighth preamble group for 2-step RACH procedure.
2. 2 . The method of claim 1 , wherein the plurality of RACH resources for small data transmission associated with the RRC inactive state comprises at least one of: a 2-step RACH resource; or a 4-step RACH resource.
3. 3 . The method of claim 1 , wherein the plurality of RACH resources for small data transmission associated with the RRC inactive state are configured on a bandwidth part (BWP).
4. 4 . The method of claim 1 , wherein an amount of the small data does not exceed a data amount threshold.
5. 5 . The method of claim 1 , further comprising: retransmitting, by the wireless user device in the RRC inactive state, the Msg 3 .
6. 6 . The method of claim 1 , further comprising: after the transmitting the Msg 3 , maintaining, by the wireless user device, the RRC inactive state.
7. 7 . The method of claim 1 , further comprising: after the transmitting the small data, performing, by the wireless user device, a random access procedure to transition from the RRC inactive state to a second RRC connected state.
8. 8 . The method of claim 1 , further comprising: receiving, by the wireless user device, a message, for the selected RACH resource, indicating at least one of: a mapping between one RACH occasion and one or more synchronization signal blocks (SSBs); or a mapping between one or more contention-based preambles and one synchronization signal block (SSB).
9. 9 . The method of claim 1 , wherein the RRC release message indicates: a transition from the RRC connected state to the RRC inactive state; and a small data configuration for the RRC inactive state.
10. 10 . The method of claim 1 , further comprising: determining, based on a measurement of a reference signal received power of a synchronization signal block (SSB), a 2-step RACH for transmission of uplink data or a 4-step RACH for transmission of the uplink data.
11. 11 . The method of claim 1 , wherein the system information further indicates: a second RACH resource for contention-based random access for transition to an RRC connected state; and a third RACH resource for contention-free random access for transition to an RRC connected state.
12. 12 . The method of claim 1 , wherein the system information further indicates: a second RACH resource for 2-step random access for transition to an RRC connected state; and a third RACH resource for 4-step random access for transition to an RRC connected state.
13. 13 . A method comprising: receiving, by a wireless user device, configuration parameters indicating a plurality of physical random access channel (PRACH) configurations, wherein the plurality of PRACH configurations comprise: a plurality of first random access channel (RACH) resources for small data transmission associated with a radio resource control (RRC) inactive state; a second RACH resource for contention-based random access; and a third RACH resource for contention-free random access; receiving, by the wireless user device in an RRC connected state, an RRC release message, wherein the RRC release message indicates transition from the RRC connected state to the RRC inactive state; transmitting, by the wireless user device in the RRC inactive state to a base station, a message A (MsgA) for a 2-step RACH procedure, wherein the MsgA comprises a preamble and MsgA physical uplink shared channel (MsgA PUSCH), wherein the MsgA PUSCH comprises a buffer status report medium access control control element (BSR MAC CE), and wherein the BSR MAC CE indicates a data size; receiving, by the wireless user device in the RRC inactive state, a fallback random access response (RAR) comprising an uplink (UL) grant; and based on the UL grant, transmitting, by the wireless user device in the RRC inactive state, a message 3 (Msg3) to the base station via a selected RACH resource for 4-step RACH procedure, wherein the Msg3 comprises common control channel (CCCH) data and small data, wherein the plurality of PRACH configurations comprises a first PRACH configuration for small data transmission, wherein the first PRACH configuration comprises a first preamble group for 4-step RACH procedure, a second preamble group for 4-step RACH procedure, a third preamble group for 2-step RACH procedure, and a fourth preamble group for 2-step RACH procedure, and wherein the plurality of PRACH configurations further comprises a second PRACH configuration for small data transmission, and wherein the second PRACH configuration comprises a fifth preamble group for 4-step RACH procedure, a sixth preamble group for 4-step RACH procedure, a seventh preamble group for 2-step RACH procedure, and an eighth preamble group for 2-step RACH procedure.
14. 14 . The method of claim 13 , further comprising: after the transmitting the Msg3, maintaining, by the wireless user device, the RRC inactive state.
15. 15 . The method of claim 13 , wherein the second RACH resource for contention-based random access comprises at least one of: a 2-step RACH resource for contention-based random access for transition to an RRC connected state; or a 4-step RACH resource for contention-based random access for transition to an RRC connected state.
16. 16 . The method of claim 13 , wherein the third RACH resource for contention-free random access comprises at least one of: a 2-step RACH resource for contention-free random access for transition to an RRC connected state; or a 4-step RACH resource for contention-free random access for transition to an RRC connected state.
17. 17 . The method of claim 13 , further comprising: after the transmitting the Msg3, performing, by the wireless user device, a random access procedure to transition from the RRC inactive state to a second RRC connected state.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application is a continuation of International patent application No. PCT/KR2021/007330, filed on Jun. 11, 2021, which claims priority from and the benefit of Korean Patent Application No. 10-2020-0072274, filed on Jun. 15, 2020, each of which is hereby incorporated by reference in its entirety. BACKGROUND The present disclosure may provide a method and apparatus for transmitting small data in a wireless communication system. More particularly, the present disclosure may provide a method and apparatus in which a radio resource control (RRC) inactive user equipment (UE) transmits small data through a random access channel (RACH) procedure. International Mobile Telecommunication (IMT) framework and standard are being developed in the International Telecommunication Union (ITU). Also, in the recent times, discussion for 5-th generation (5G) communication is ongoing through a program called “IMT for 2020 and beyond.” To meet the requirements requested by “IMT for 2020 and beyond,” discussion is being made to support various numerologies about a time-frequency resource unit standard by considering various scenarios, service requirements, and potential system compatibility in a 3-rd Generation Partnership Project (3GPP) new radio (NR) system. Also, to overcome a poor channel environment, such as high path-loss, phase-noise, and frequency offset, occurring on a high carrier frequency, the 5G communication may support transmission of a physical signal/channel through a plurality of beams. Through this, the 5G communication may support applications, for example, enhanced Mobile Broadband (eMBB), massive Machine Type Communications (mMTC)/ultra Machine Type Communications (uMTC), and Ultra Reliable and Low Latency Communications (URLLC). SUMMARY The present disclosure may provide a method and apparatus for transmitting small data through a random access channel (RACH) procedure. The present disclosure may provide a method and apparatus for allocating a resource for small data transmission. The present disclosure may provide a method and apparatus for additionally setting a PRACH configuration for small data transmission. The present disclosure may provide a method and apparatus for transmitting small data based on a contention-based random access (CBRA). The present disclosure may provide a method and apparatus for transmitting small data based on a contention-free random access (CFRA). The present disclosure may provide a method of transmitting, by a user equipment (UE), small data in a wireless communication system. Here, a small data transmission method may include enabling a small data configuration in the UE; triggering, by the UE, a small data transmission; transmitting, by the UE, a common control channel (CCCH) and buffered data information to a base station in a random access channel (RACH) procedure; receiving a random access response (RAR) including an uplink (UL) grant from the base station based on the buffered data information; and transmitting the small data based on the UL grant. The present disclosure may provide a method of transmitting, by a UE, small data in a wireless communication system. Here, a small data transmission method may include enabling a plurality of small data configurations in the UE; triggering, by the UE, a small data transmission; selecting, by the UE, a preamble group based on a CCCH size and an uplink data size; randomly selecting, by the UE, and transmitting a preamble within the preamble group; and transmitting the uplink data. According to the present disclosure, there may be provided a method and apparatus for transmitting small data through a random access channel (RACH) channel. Through this, a user equipment (UE) may transmit uplink data without shifting to a radio resource control (RRC) connected state. The present disclosure may provide a method and apparatus for allocating a resource for small data transmission. Here, the resource may be allocated by comparing a common control channel (CCCH) and an uplink data size with a transport block size (TBS). The present disclosure may provide a method and apparatus for additionally configurating a PRACH configuration for small data transmission and, through this, may use an additional PRACH configuration for the small data transmission. The present disclosure may provide a method and apparatus for transmitting small data based on a contention-based random access (CBRA) and, through this, may effectively select a resource for small data transmission. The present disclosure may provide a method and apparatus for transmitting small data based on a contention-free random access (CFRA) and, through this, may effectively select a resource for small data transmission. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 illustrates a slot length to which the present disclosure may apply. FIG. 2 illustrates a structure of a synchronization signal block to which the present disclosure may apply. FIG. 3