EP-4738745-A2 - METHOD AND APPARATUS FOR PERFORMING CONFIGURED GRANT BASED SMALL DATA TRANSMISSION BY USER EQUIPMENT IN WIRELESS COMMUNICATION SYSTEM

EP4738745A2EP 4738745 A2EP4738745 A2EP 4738745A2EP-4738745-A2

Abstract

A method for performing a configured grant based small data transmission (CG-SDT) in a Radio Resource Control (RRC) INACTIVE state by a user equipment (UE) in a wireless communication system is disclosed. The method comprises steps of performing an initial transmission for the CG-SDT on a configured grant (CG), wherein a configured grant timer (CGT) and a CG-SDT-retransmission timer (CG-SDT-RT) are started by performing the initial transmission; and based on a physical downlink control channel (PDCCH) related to the initial transmission not being received until the CG-SDT-RT expiring during the CGT is running, performing a retransmission of the initial transmission, wherein the CG-SDT-RT is re-started upon performing the retransmission of the initial transmission, wherein, based on the PDCCH related to the initial transmission not being received until the CGT expiring, a SDT failure handling procedure is triggered.

Inventors

YI, SEUNGJUNE
LEE, SUNYOUNG

Assignees

LG Electronics Inc.

Dates

Publication Date: 20260506
Application Date: 20220912

Claims (13)

A method comprising: starting, a medium access control, MAC, entity of a user equipment, UE, a configured grant timer, CGT, and a CG-SDT-retransmission timer, CG-SDT-RT, based on an initial transmission for a CG-SDT being performed in a Radio Resource Control, RRC, INACTIVE state; and restarting, by the MAC entity, the CG-SDT-RT based on a retransmission of the initial transmission for the CG-SDT being performed in the RRC INACTIVE state, wherein based on the CGT being expired and based on a physical downlink control channel, PDCCH, not being received after the initial transmission for the CG-SDT, a SDT procedure is considered a failure.
The method of claim 1, wherein, based on the SDT procedure being considered the failure, the MAC entity is reset.
The method of claim 1, wherein, based on the SDT procedure being considered the failure, the RRC INACTIVE state is transitioned to a RRC IDLE state.
The method of claim 1, wherein the PDCCH comprises an acknowledgement, ACK, response of the initial transmission for the CG-SDT.
The method of claim 1, wherein based on the PDCCH not being received until the CG-SDT-RT expiring, the retransmission of the initial transmission for the CG-SDT is performed.
The method of claim 1, wherein based on the CGT being expired and based on the PDCCH being received after the initial transmission for the CG-SDT, a subsequent initial transmission for the CG-SDT is performed.
A user equipment, UE, in a wireless communication system, the UE comprising: at least one processor; and at least one computer memory storing instructions that, when executed by the at least one processor, cause a medium access control, MAC, entity of the UE to perform operations comprising: starting, a medium access control, MAC, entity of a user equipment, UE, a configured grant timer, CGT, and a CG-SDT-retransmission timer, CG-SDT-RT, based on an initial transmission for a CG-SDT being performed in a Radio Resource Control, RRC, INACTIVE state; and restarting, by the MAC entity, the CG-SDT-RT based on a retransmission of the initial transmission for the CG-SDT being performed in the RRC INACTIVE state, wherein based on the CGT being expired and based on a physical downlink control channel, PDCCH, not being received after the initial transmission for the CG-SDT, a SDT procedure is considered a failure.
The UE of claim 7, wherein, based on the SDT procedure being considered the failure, the MAC entity is reset.
The UE of claim 7, wherein, based on the SDT procedure being considered the failure, the RRC INACTIVE state is transitioned to a RRC IDLE state.
The UE of claim 7, wherein the PDCCH comprises an acknowledgement, ACK, response of the initial transmission for the CG-SDT.
The UE of claim 7, wherein based on the PDCCH not being received until the CG-SDT-RT expiring, the retransmission of the initial transmission for the CG-SDT is performed.
The UE of claim 7, wherein based on the CGT being expired and based on the PDCCH being received after the initial transmission, a subsequent initial transmission for the CG-SDT is performed.
A non-transitory computer-readable storage medium comprising program instructions that, when executed by a processor, cause a medium access control, MAC, entity of a user equipment, UE, to perform operations comprising: starting, a medium access control, MAC, entity of a user equipment, UE, a configured grant timer, CGT, and a CG-SDT-retransmission timer, CG-SDT-RT, based on an initial transmission for a CG-SDT being performed in a Radio Resource Control, RRC, INACTIVE state; and restarting, by the MAC entity, the CG-SDT-RT based on a retransmission of the initial transmission for the CG-SDT being performed in the RRC INACTIVE state, wherein based on the CGT being expired and based on a physical downlink control channel, PDCCH, not being received after the initial transmission for the CG-SDT, a SDT procedure is considered a failure.

Description

BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to a wireless communication system, and more particularly, to a method for performing a configured grant based small data transmission (CG-SDT) by a user equipment (UE) in a wireless communication system and an apparatus therefor. Discussion of the Related Art Introduction of new radio communication technologies has led to increases in the number of user equipments (UEs) to which a base station (BS) provides services in a prescribed resource region, and has also led to increases in the amount of data and control information that the BS transmits to the UEs. Due to typically limited resources available to the BS for communication with the UE(s), new techniques are needed by which the BS utilizes the limited radio resources to efficiently receive/transmit uplink/downlink data and/or uplink/downlink control information. In particular, overcoming delay or latency has become an important challenge in applications whose performance critically depends on delay/latency. SUMMARY OF THE INVENTION Accordingly, the present disclosure is directed to a method for performing a configured grant based small data transmission (CG-SDT) by a user equipment (UE) in a wireless communication system and an apparatus therefor, which substantially obviate one or more problems due to limitations and disadvantages of the related art. Additional advantages, objects, and features of the specification will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the specification. The objectives and other advantages of the specification may be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings. A method for performing a configured grant based small data transmission (CG-SDT) in a Radio Resource Control (RRC) INACTIVE state by a user equipment (UE) in a wireless communication system according to the embodiment of the present invention comprises the steps of performing an initial transmission for the CG-SDT on a configured grant (CG), wherein a configured grant timer (CGT) and a CG-SDT-retransmission timer (CG-SDT-RT) are started by performing the initial transmission; and based on a physical downlink control channel (PDCCH) related to the initial transmission not being received until the CG-SDT-RT expiring during the CGT is running, performing a retransmission of the initial transmission, wherein the CG-SDT-RT is re-started upon performing the retransmission of the initial transmission, wherein, based on the PDCCH related to the initial transmission not being received until the CGT expiring, a SDT failure handling procedure is triggered. Further, a user equipment (UE) in a wireless communication system according to the present invention comprises at least one transceiver; at least one processor; and at least one computer memory operably connectable to the at least one processor and storing instructions that, when executed, cause the at least one processor to perform operations comprising: performing an initial transmission for a configured grant based small data transmission (CG-SDT) on a configured grant (CG) in a Radio Resource Control (RRC) INACTIVE state, wherein a configured grant timer (CGT) and a CG-SDT-retransmission timer (CG-SDT-RT) are started by performing the initial transmission; and based on a physical downlink control channel (PDCCH) related to the initial transmission not being received until the CG-SDT-RT expiring during the CGT is running, performing a retransmission of the initial transmission, wherein the CG-SDT-RT is re-started upon performing the retransmission of the initial transmission, wherein, based on the PDCCH related to the initial transmission not being received until the CGT expiring, a SDT failure handling procedure is triggered. Preferably, the SDT failure handling procedure comprises resetting a medium access control (MAC) entity of the UE. More preferably, the SDT failure handling procedure further comprises transitioning the RRC INACTIVE state to a RRC IDLE state. Preferably, based on the PDCCH related to the initial transmission being received during the CGT is running, a subsequent transmission for the CG-SDT on the CG is performed, wherein the CGT is started upon performing the subsequent transmission and the CG-SDT-RT is not started. Preferably, the PDCCH related to the initial transmission is an acknowledge (ACK) response of the initial transmission for the CG-SDT. It will be appreciated by persons skilled in the art that the effects that can be achieved through the present invention are not limited to what has been particularly described hereinabove and other advantages of the present invention will be more clearly understood from the following detailed description. BRIEF DESCRIPTION OF T