WO2022082522A1

WO2022082522A1 - Method and apparatus for subsequent data transmission

Info

Publication number: WO2022082522A1
Application number: PCT/CN2020/122572
Authority: WO
Inventors: Jie Shi; Haiming Wang; Lianhai WU; Ran YUE; Jing HAN
Original assignee: Lenovo (Beijing) Limited
Priority date: 2020-10-21
Filing date: 2020-10-21
Publication date: 2022-04-28

Abstract

Embodiments of the present application are directed to a method and apparatus for subsequent data transmission. In an embodiment of the present application, the method includes: transmitting a first uplink (UL) data in Msg. A of 2-step random access channel (RACH) procedure; receiving resource for a dedicated preamble for a subsequent UL data transmission; transmitting the subsequent UL data transmission based on the dedicated preamble; and monitoring downlink (DL) response message.

Description

METHOD AND APPARATUS FOR SUBSEQUENT DATA TRANSMISSION

TECHNICAL FIELD

Embodiments of the present application generally relate to wireless communication technology, especially to a method and apparatus for subsequent data transmission.

BACKGROUND

For a user equipment (UE) in RRC_INACTIVE state (also called an inactive mode UE) , it is possible to transmit uplink (UL) small data to a base station (BS) in an initial random access procedure, such as, 2-step random access channel (RACH) procedure or 4-step RACH procedure. Furthermore, the UE may have subsequent UL small data to be transmitted, and the network (the BS) may have downlink (DL) data to be transmitted. Therefore, how to perform the subsequent UL/DL data transmission when the UE is in inactive mode needs to be considered.

SUMMARY OF THE APPLICATION

Embodiments of the present application provide a method and apparatus for subsequent data transmission.

An embodiment of the present application provides a method performed by a user equipment (UE) in inactive mode or in idle mode. The method may include: transmitting a first uplink (UL) data in Msg. A of 2-step random access channel (RACH) procedure; receiving resource for a dedicated preamble for a subsequent UL data; transmitting the subsequent UL data based on the dedicated preamble; and monitoring downlink (DL) response message.

In an embodiment of the present application, the resource for the dedicated preamble is received in Msg. B of 2-step RACH procedure or in subsequent UL or DL scheduling information. The subsequent UL or DL scheduling information could be downlink control information (DCI) for UL or DL scheduling, or radio resource control (RRC) message or media access control (MAC) control element (CE) including subsequent UL or DL scheduling information. The resource for the dedicated preamble could also be extended to include physical uplink share channel (PUSCH) resource associated to this dedicated preamble. The resource for the dedicated preamble could be at least one of the time/frequency resource and sequence/code resource.

In an embodiment of the present application, the resource for the dedicated preamble is received via at least one of radio resource control (RRC) message, a media access control (MAC) control element (CE) , or physical layer signalling.

In an embodiment of the present application, the method may further include: receiving indication information to indicate the resource for the dedicated preamble being applied for one shot, a plurality of shots, an entire small data transmission procedure for the UE in inactive mode or idle mode, or when a first timer is running, or during a period.

In an embodiment of the present application, the DL response message is monitored in a window or when a second timer is running.

In an embodiment of the present application, the method may further include: if a successful DL response message is not received in the window, or when the second timer is running, or until the second timer is expired, increasing a number of failure (s) of the 2-step RACH based small data transmission procedure by 1.

In an embodiment of the present application, the method may further include: if the number of failure (s) of the 2-step RACH based small data transmission procedure is greater than a threshold, transmitting a subsequent UL data by 4-step RACH procedure, wherein the 4-step RACH procedure is for small data transmission for the UE in inactive mode or idle mode, or for non-small data transmission for the UE in inactive mode or idle mode, or not for small data transmission. Here, the threshold for transmitting a subsequent UL data transmission by 4-step RACH procedure for small data transmission for the UE in inactive mode or idle mode, or for non-small data transmission for the UE in inactive mode or idle mode, or not for small data transmission could be different. This means that the threshold is related to the specific 4-step RACH procedure. For example, the 4-step RACH procedure is for small data transmission for the UE in inactive mode or idle mode, or for non-small data transmission for the UE in inactive mode or idle mode, or not for small data transmission. This threshold may be configured to the UE by RRC message, or SIB information, or MAC CE. If the number of failure (s) of the 2-step RACH procedure for small data transmission for the UE in inactive mode or idle mode is greater than another threshold, the UE could initiate the 2-step RACH procedure for non-small data transmission for UE in active mode or idle mode. Then, the UE could report its BSR for small data transmission for UE in inactive mode or idle mode in MsgA of this the 2-step RACH procedure for non-small data transmission for UE in active mode or idle mode. This threshold is configured to the UE by RRC message, or SIB information, or MAC CE.

Usually, when the number of the UE not successful in 2-step RACH procedure for small data transmission for the UE in inactive mode or idle mode is greater than a threshold, the UE will have a priority to initiate the 4-step RACH procedure for small data transmission for the UE in inactive mode or idle mode. The number of the UE not successful in 2-step RACH procedure is greater than a threshold, for example, which means that the PREAMBLE_TRANSMISSION_COUNTER for 2-step RACH procedure for small data transmission for the UE in inactive mode or idle mode is greater than a threshold, or equals to a threshold+1.

In an embodiment of the present application, the method may further include: receiving a DL data which is multiplexed in the DL response message.

In an embodiment of the present application, the method may further include: monitoring and receiving a DL data based on discontinuous reception (DRX) or DL semi-persistent scheduling (SPS) .

In an embodiment of the present application, the method may further include: receiving at least one configuration of the DRX or the DL SPS in a radio resource control (RRC) release message or in a RRC message when the UE transitions from a connected mode to the inactive mode, when the UE transitions from the connected mode to the idle mode, or when the UE is in the inactive mode or the idle mode, wherein the RRC release message or the RRC message enables the UE in the inactive mode or in the idle mode to transmit or receive data, or transmit or receive data in configured grant (CG) resources.

In an embodiment of the present application, the method may further include: transmitting indication information to indicate one configuration of the DRX or the DL SPS for small data transmission for the UE in inactive mode or idle mode; and/or receiving indication information to indicate one configuration of the DRX or one or more dedicated configuration of the DL SPS.

In an embodiment of the present application, the method may further include: receiving configuration of the DRX or the DL SPS in the 2-step RACH procedure.

In an embodiment of the present application, the configuration of the DRX or the DL SPS is per data radio bearer (DRB) or per traffic pattern.

In an embodiment of the present application, receiving indication information to indicate the DRX or DL SPS being applied for one shot, a plurality of shots, an entire small data transmission procedure for the UE in inactive mode or idle mode, or when a timer is running, or until the small data transmission procedure is ended.

In an embodiment of the present application, the method may further include: storing or releasing the configuration of the DRX or the DL SPS based on network indication or specified UE behavior when small data transmission procedure for the UE in inactive mode or idle mode is ended.

Another embodiment of the present application provides a method performed by a user equipment (UE) in inactive mode or in idle mode. The method may include: transmitting a first uplink (UL) data in Msg. 3 of 4-step random access channel (RACH) procedure; receiving UL scheduling information for a subsequent UL transmission in Msg. 4 of 4-step random access channel (RACH) procedure, and/or receiving downlink (DL) assignment information for a subsequent DL transmission in Msg. 4 of 4-step RACH procedure; transmitting the subsequent UL transmission based on the UL scheduling information; and monitoring DL response message, and/or receiving the subsequent DL transmission based on the DL assignment information, where the UL scheduling information is one of UL grant and a dedicated preamble in Msg. A of 2-step RACH procedure.

In an embodiment of the present application, in the case that the UL scheduling information is UL grant, the subsequent UL transmission is transmitted based on the UL grant.

In an embodiment of the present application, in the case that the UL scheduling information is a dedicated preamble in Msg. A of 2-step RACH procedure, the subsequent UL transmission is transmitted based on the dedicated preamble in Msg. A of 2-step RACH procedure.

In an embodiment of the present application, receiving indication information to indicate the UL grant or the dedicated preamble being applied for one shot, a plurality of shots, an entire small data transmission procedure for the UE in inactive mode or idle mode, or when a first timer is running.

In an embodiment of the present application, the method may further include: receiving and storing at least one configuration of the DRX or the DL SPS in a radio resource control (RRC) release message or in a RRC message when the UE transitions from a connected mode to the inactive mode, when the UE transitions from the connected mode to the idle mode, or when the UE is in the inactive mode or the idle mode, where the RRC release message or the RRC message enables the UE in the inactive mode or in the idle mode to transmit or receive data, or transmit or receive data in configured grant (CG) resources.

In an embodiment of the present application, the method may further include: transmitting indication information to indicate one configuration of the DRX or the DL SPS for small data transmission for the UE the inactive mode or the idle mode; and/or receiving indication information to indicate one configuration of the DRX or one or more dedicated configuration of the DL SPS.

In an embodiment of the present application, the method may further include: receiving configuration of the DRX or the DL SPS in the 4-step RACH procedure. For example, the configuration of the DRX or the DL SPS may be received in the Msg. 2 or Msg. 4 in 4-step RACH procedure.

In an embodiment of the present application, the method may further include: storing or releasing the configuration of the DRX or the DL SPS based on network indication or UE behavior when small data transmission procedure for the UE in inactive mode or idle mode is ended.

In an embodiment of the present application, the DL assignment is applied for one shot, a plurality of shots, an entire data transmission procedure, or when a third timer is running.

In an embodiment of the present application, the method may further include: receiving indication information to indicate the DRX or DL SPS being applied for one shot, a plurality of shots, an entire small data transmission procedure for the UE in inactive mode or idle mode, or when a timer is running, or until the small data transmission procedure is ended.

In an embodiment of the present application, the number of shot in a plurality of shots could be configured by network to UE.

Another embodiment of the present application provides a method performed by a user equipment (UE) in inactive mode or in idle mode. The method may include: monitoring and receiving a DL data based on discontinuous reception (DRX) or DL semi-persistent scheduling (SPS) .

In an embodiment of the present application, the method may further include: receiving configuration of the DRX or the DL SPS in CG based small data transmission procedure for UE in inactive mode or idle mode.

In an embodiment of the present application, the configuration of the DRX or the DL SPS is per data radio bearer (DRB) or per traffic pattern. It could be applied to UE in duration or until the end of small data transmission in UE inactive mode or idle mode.

Another embodiment of the present application provides a method performed by a user equipment (UE) in inactive mode or in idle mode. The method may include: transmitting a measurement result of a serving cell of the UE; and/or transmitting indication information to indicate that the UE be able or disable to apply 2-step RACH procedure for small data transmission for the UE in inactive mode or idle mode, and/or to indicate that the UE be able or disable to apply CG resource for small data transmission for the UE in inactive mode or idle mode. Be able or disable to the small data transmission procedure means that UE is available or not available to the small data transmission procedure.

In an embodiment of the present application, the method may further include: receiving indication information to indicate the UE to report that the UE is able or disable to apply 2-step RACH procedure for small data transmission for the UE in inactive mode or idle mode, or indicate the UE to report its measurement result to serving cell, or receiving indication information to indicate the UE to report that the UE is able or disable to apply CG resource for small data transmission for the UE in inactive mode or idle mode., or receiving indication information to indicate the UE is able or disable to apply 2-step RACH procedure for small data transmission for the UE in inactive mode or idle mode, or indicate the UE is able or disable to report its measurement result to serving cell, or indicate the UE is able or disable to apply CG resource for small data transmission for the UE in inactive mode or idle mode. The indication information is transmitted in small data transmission procedure in UE inactive mode or idle mode. The indication information is transmitted in RRC message, system information block, or MAC CE.

In an embodiment of the present application, after transition to 2-step RACH procedure from 4-step RACH procedure, radio network temporary identity (RNTI) for the UE in 4-step RACH procedure is used in 2-step RACH procedure.

Another embodiment of the present application provides a method performed by a UE. The method may include: initiating 4-step random access channel (RACH) procedure for small data transmission for the UE in inactive mode or idle mode, or initiating 2-step RACH procedure for non-small data transmission for the UE in inactive mode or idle mode, if PREAMBLE_TRANSMISSION_COUNTER for 2-step RACH procedure for small data transmission for the UE in inactive mode or idle mode is greater than a threshold, or equals to a threshold+1.

In an embodiment of the present application, the method may further include: receiving an indication from network to initiate the 4-step RACH procedure for small data transmission for the UE in inactive mode or idle mode, or to initiate the 2-step RACH procedure for non-small data transmission for the UE in inactive mode or idle mode, when PREAMBLE_TRANSMISSION_COUNTER for 2-step RACH procedure for small data transmission for the UE in inactive mode or idle mode is greater than the threshold, or equals to the threshold+1; or directly initiating the 4-step RACH procedure for small data transmission for the UE in inactive mode or idle mode, or initiating the 2-step RACH procedure for non-small data transmission for the UE in inactive mode or idle mode, when PREAMBLE_TRANSMISSION_COUNTER for 2-step RACH procedure for small data transmission for the UE in inactive mode or idle mode is greater than the threshold, or equals to the threshold+1.

In an embodiment of the present application, the threshold is received by at least one of RRC message, system information blocks, or MAC CE.

In an embodiment of the present application, the method may further include: receiving UL grant for Msg. 3 transmission with UL data from network if the UE initiates 4-step RACH procedure for small data transmission for the UE in inactive mode or idle mode.

In an embodiment of the present application, the method may further include: initiating 2-step RACH procedure for non-small data transmission for the UE in inactive mode or idle mode, if the UE is in 4-step RACH procedure for small data transmission for the UE in inactive mode or idle mode.

In an embodiment of the present application, the method may further include: initiating 2-step RACH procedure for non-small data transmission for the UE in inactive mode or idle mode based on specified UE behavior or network indication, if the UE initiates 4-step RACH procedure for small data transmission for the UE in inactive mode or idle mode, if the PREAMBLE_TRANSMISSION_COUNTER for 4-step RACH procedure for small data transmission for the UE in inactive mode or idle mode is greater than a threshold, or equals to a threshold+1.

In an embodiment of the present application, the UE will select the small data transmission procedure based on the priority that 2-step RACH procedure for small data transmission for the UE in inactive mode or idle mode is prior to that 4-step RACH procedure for small data transmission for the UE in inactive mode or idle mode. The UE will select the data transmission procedure based on the priority that 4-step RACH procedure for small data transmission for the UE in inactive mode or idle mode is prior to that 2-step RACH procedure for non-small data transmission for the UE in inactive mode or idle mode. The reason is that, for some UEs, the service may be urgent and data size is greater than a threshold, so the UE needs to transmit the UL data based on 4-step RACH procedure for SDT transmission for the UE in inactive mode or idle mode. Usually, the 4-step RACH procedure for SDT transmission for the UE in inactive mode or idle mode could contain large data size than 2-step RACH procedure for non-small data transmission for the UE in inactive mode or idle mode.

In an embodiment of the present application, the UE will select the small data transmission procedure based on the priority that 2-step RACH procedure for small data transmission for the UE in inactive mode or idle mode is prior to that 2-step RACH procedure for non-small data transmission for the UE in inactive mode or idle mode. The UE will select the data transmission procedure based on the priority that 2-step RACH procedure for non-small data transmission for the UE in inactive mode or idle mode is prior to 4-step RACH procedure for small data transmission for the UE in inactive mode or idle mode. The reason is that, for some UE, the service may be urgent or data size is not larger than a threshold, so UE needs to transmit the UL data based on 2-step RACH procedure for non-small data transmission for the UE in inactive mode or idle mode. Usually, the 4-step RACH procedure for SDT transmission for the UE in inactive mode or idle mode could contain large data size than 2-step RACH procedure for non-small data transmission for the UE in inactive mode or idle mode, but 2-step RACH procedure could transmit the data at the first message, the delay is short.

Another embodiment of the present application provides a method performed by a base station (BS) . The method may include: receiving a first uplink (UL) data in Msg. A of 2-step random access channel (RACH) procedure; transmitting resource for a dedicated preamble for a subsequent UL data; receiving the subsequent UL data based on the dedicated preamble; and transmitting downlink (DL) response message.

In an embodiment of the present application, the resource for the dedicated preamble is transmitted in Msg. B of 2-step RACH procedure or in subsequent UL or DL scheduling information.

In an embodiment of the present application, the resource for the dedicated preamble is transmitted via at least one of radio resource control (RRC) message, a media access control (MAC) control element (CE) , or physical layer signalling.

In an embodiment of the present application, the method may further include: transmitting indication information to indicate the resource for the dedicated preamble being applied for one shot, a plurality of shots, an entire small data transmission procedure for the UE in inactive mode or idle mode, when a first timer is running, or during a period.

In an embodiment of the present application, the DL response message is transmitted in a window or when a second timer is running.

In an embodiment of the present application, the method may further include: if a successful DL response message is not transmitted in the window, or when the second timer is running, or until the second timer is expired, increasing a number of failure (s) of the 2-step RACH based small data transmission procedure by 1.

In an embodiment of the present application, the method may further include: if the number of failures of the 2-step RACH procedure based small data transmission is greater than a threshold, receiving a subsequent UL data transmission by 4-step RACH procedure, wherein the 4-step RACH procedure is for small data transmission for the UE in inactive mode or idle mode, or for non-small data transmission for the UE in inactive mode or idle mode, or not for small data transmission.

In an embodiment of the present application, the method may further include: transmitting a DL data which is multiplexed in the DL response message.

In an embodiment of the present application, the method may further include: transmitting a DL data based on discontinuous reception (DRX) or DL semi-persistent scheduling (SPS) .

In an embodiment of the present application, the method may further include: transmitting at least one configuration of the DRX or the DL SPS in a radio resource control (RRC) release message or in a RRC message when the UE transitions from a connected mode to the inactive mode, when the UE transitions from the connected mode to the idle mode, or when the UE is in the inactive mode or the idle mode, where the RRC release message or the RRC message enables the UE in the inactive mode or in the idle mode to transmit or receive data, or transmit or receive data in configured grant (CG) resources.

In an embodiment of the present application, the method may further include: receiving indication information to indicate one configuration of the DRX or the DL SPS for small data transmission for the UE in inactive mode or idle mode; and/or transmitting indication information to indicate one configuration of the DRX or one or more dedicated configuration of the DL SPS based on the received indication information.

In an embodiment of the present application, the method may further include: transmitting configuration of the DRX or the DL SPS in the 2-step RACH procedure.

In an embodiment of the present application, the method may further include: transmitting indication information for a user equipment (UE) to store or release the configuration of the DRX or the DL SPS when small data transmission procedure for the UE in inactive mode or idle mode is ended.

Another embodiment of the present application provides a method performed by a base station (BS) . The method may include: receiving a first uplink (UL) data in Msg. 3 of 4-step random access channel (RACH) procedure; transmitting UL scheduling information for a subsequent UL transmission in Msg. 4 of 4-step random access channel (RACH) procedure, and/or transmitting downlink (DL) assignment information for a subsequent DL transmission in Msg. 4 of 4-step RACH procedure; receiving the subsequent UL transmission based on the UL scheduling information; and transmitting downlink (DL) response message, and/or transmitting the subsequent DL transmission based on the DL assignment information, where the UL scheduling information is one of UL grant and a dedicated preamble in Msg. A of 2-step RACH procedure.

In an embodiment of the present application, in the case that the UL scheduling information is UL grant, the subsequent UL transmission is received based on the UL grant.

In an embodiment of the present application, in the case that the UL scheduling information is a dedicated preamble in Msg. A of 2-step RACH procedure, the subsequent UL transmission is received based on the dedicated preamble in Msg. Aof 2-step RACH procedure.

In an embodiment of the present application, the method may further include: transmitting indication information to indicate the UL grant or the dedicated preamble being applied for one shot, a plurality of shots, an entire small data transmission procedure for the UE in inactive mode or idle mode, or when a first timer is running.

In an embodiment of the present application, the method may further include: receiving indication information to indicate one configuration of the DRX or the DL SPS for small data transmission for the UE the inactive mode or the idle mode; and/or transmitting indication information to indicate one configuration of the DRX or one or more dedicated configuration of the DL SPS.

In an embodiment of the present application, the method may further include: transmitting configuration of the DRX or the DL SPS in the 4-step RACH procedure.

Another embodiment of the present application provides a method performed by a base station (BS) . The method may include: receiving a measurement result of a serving cell of the UE; and/or receiving indication information to indicate that the UE be able or disable to apply 2-step RACH procedure for small data transmission for the UE in inactive mode or idle mode, and/or to indicate that the UE be able or disable to apply CG resource for small data transmission for the UE in inactive mode or idle mode.

In an embodiment of the present application, the method may further include: transmitting indication information to indicate the UE to report that the UE is able or disable to apply 2-step RACH procedure for small data transmission for the UE in inactive mode or idle mode, or indicate the UE to report its measurement result to serving cell, or receiving indication information to indicate the UE to report that the UE is able or disable to apply CG resource for small data transmission for the UE in inactive mode or idle mode, or transmitting indication information to indicate the UE is able or disable to apply 2-step RACH procedure for small data transmission for the UE in inactive mode or idle mode, or indicate the UE is able for disable report its measurement result to serving cell, or indicate the UE is able or disable to apply CG resource for small data transmission for the UE in inactive mode or idle mode. Be able or disable to the small data transmission procedure means that UE is available or not available to the small data transmission procedure.

Another embodiment of the present application provides a method performed by a base station (BS) . The method may include: receiving a UL data by 4-step random access channel (RACH) procedure for small data transmission for the UE in inactive mode or idle mode, or by 2-step RACH procedure for non-small data transmission for the UE in inactive mode or idle mode, if PREAMBLE_TRANSMISSION_COUNTER for 2-step RACH procedure for small data transmission for the UE in inactive mode or idle mode is greater than a threshold, or equals to a threshold+1.

In an embodiment of the present application, the method may further include: transmitting an indication to initiate the 4-step RACH procedure for small data transmission for the UE in inactive mode or idle mode, or to initiate the 2-step RACH procedure for non-small data transmission for the UE in inactive mode or idle mode, when PREAMBLE_TRANSMISSION_COUNTER for 2-step RACH procedure for small data transmission for the UE in inactive mode or idle mode is greater than the threshold, or equals to the threshold+1.

In an embodiment of the present application, the method may further include: transmitting UL grant for Msg. 3 transmission with UL data from network if the UE initiates 4-step RACH procedure for small data transmission for the UE in inactive mode or idle mode.

In an embodiment of the present application, the method may further include: receiving a UL data by 2-step RACH procedure for non-small data transmission for the UE in inactive mode or idle mode, if the UE is in 4-step RACH procedure for small data transmission for the UE in inactive mode or idle mode.

In an embodiment of the present application, the method may further include: receiving a UL data by 2-step RACH procedure for non-small data transmission for the UE in inactive mode or idle mode based on specified UE behavior or network indication, if the UE initiates 4-step RACH procedure for small data transmission for the UE in inactive mode or idle mode, if the PREAMBLE_TRANSMISSION_COUNTER for 4-step RACH procedure for small data transmission for the UE in inactive mode or idle mode is greater than a threshold, or equals to a threshold+1.

Another embodiment of the present application provides an apparatus. The apparatus may include at least one non-transitory computer-readable medium having computer executable instructions stored therein; at least one receiver; at least one transmitter; and at least one processor coupled to the at least one non-transitory computer-readable medium, the at least one receiver and the at least one transmitter. The computer executable instructions are programmed to implement the above method with the at least one receiver, the at least one transmitter and the at least one processor.

The embodiments of the present application may perform the subsequent UL/DL data transmission with less scheduling information.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to describe the manner in which advantages and features of the application can be obtained, a description of the application is rendered by reference to specific embodiments thereof, which are illustrated in the appended drawings. These drawings depict only example embodiments of the application and are not therefore to be considered limiting of its scope.

FIG. 1 illustrates a wireless communication system according to some embodiments of the present application;

FIG. 2 illustrates another wireless communication system according to some embodiments of the present application;

FIG. 3 illustrates a flow chart of a method for subsequent data transmission according to some embodiments of the present application;

FIG. 4 illustrates a flow chart of another method for subsequent data transmission according to an embodiment of the present application;

FIG. 5 illustrates a flow chart of another method for subsequent data transmission according to an embodiment of the present application;

FIG. 6 illustrates an apparatus according to some embodiments of the present application; and

FIG. 7 illustrates another apparatus according to some other embodiments of the present application.

DETAILED DESCRIPTION

The detailed description of the appended drawings is intended as a description of preferred embodiments of the present application and is not intended to represent the only form in which the present application may be practiced. It should be understood that the same or equivalent functions may be accomplished by different embodiments that are intended to be encompassed within the spirit and scope of the present application.

Reference will now be made in detail to some embodiments of the present application, examples of which are illustrated in the accompanying drawings.

FIG. 1 illustrates a wireless communication system according to some embodiments of the present application.

As shown in FIG. 1, the wireless communication system can include at least one base station (BS) , at least one UE, and a core network (CN) node. Although a specific number of BSs and UEs, e.g., a BS (e.g., BS 102) and a UE (UE 101) are depicted in FIG. 1, one skilled in the art will recognize that any number of the BSs and UEs may be included in the wireless communication system. As shown in FIG. 1, the BS 102 may be distributed over a geographic region and may communicate with the CN node 103 via an interface.

FIG. 2 illustrates another wireless communication system according to some embodiments of the present application.

As shown in FIG. 2, the wireless communication system can include at least one BS, at least one UE, and a CN node. Although a specific number of BSs and UEs, e.g., two BSs (e.g., BS 202a and BS 202b) and a UE (UE 201) are depicted in FIG. 2, one skilled in the art will recognize that any number of the BSs and UEs may be included in the wireless communication system.

The BS 202a and the BS 202b may be distributed over a geographic region, and they may communicate with each other via an interface, for example, interface Xn. The BS 202a and the BS 202b may communicate with a CN node 203 via an interface, for example, interface NG.

In an example, the UE 201 is in a RRC_INACTIVE state (or inactive mode) . RRC_INACTIVE state is a state where a UE remains in connection management (CM) -CONNECTED and can move within an area configured by next generation-radio access network (NG-RAN) (that is, RAN notification area (RNA) ) without notifying NG-RAN. As shown in FIG. 2, the UE 201 can move within the RNA 222. The BS 202b can be the last serving BS of UE 201, and the UE 201 is currently in the cell covered by the BS 202a. For the UE 201 in RRC_INACTIVE state, the BS 202b keeps the context of the UE 201 and the associated NG connection with the CN node 203 (such as, the serving AMF and UPF) . The UE 201 in inactive mode may transmit uplink data. For example, the UE 201 may perform small data transmission. In an example, when performing the small data transmission, the BS 202a may transmit the data from the UE 201 to the BS 202b via the interface Xn, and then the BS 202b transmits the data to the CN node 203. In another example, when performing the small data transmission, the BS 202a knows that there is data from the UE 201 to be transmitted, the BS 202a first obtains the context of the UE 201 from the BS 202b and then transmits the data from the UE 201 to the CN node 203.

In the embodiments of the present application, the UE (such as, the UE 101 in FIG. 1 and the UE 201 in FIG. 2) may be a computing device, such as a desktop computer, a laptop computer, a personal digital assistant (PDA) , a tablet computer, a smart television (e.g., a television connected to the Internet) , a set-top box, a game console, a security system (including security cameras) , a vehicle on-board computer, a network device (e.g., router, switch, and modem) , or the like. According to an embodiment of the present application, the UE may be a portable wireless communication device, a smart phone, a cellular telephone, a flip phone, a device having a subscriber identity module, a personal computer, a selective call receiver, or any other device that is capable of sending and receiving communication signals on a wireless network. In some embodiments of the present application, the UE may be a wearable device, such as a smart watch, a fitness band, an optical head-mounted display, or the like. Moreover, the UE may be referred to as a subscriber unit, a mobile, a mobile station, a user, a terminal, a mobile terminal, a wireless terminal, a fixed terminal, a subscriber station, a user terminal, or a device, or described using other terminology used in the art.

In the embodiments of the present application, the BS (such as BS 102 in FIG. 1 and the BS 202a and the BS 202b in FIG. 2) may also be referred to as an access point, an access terminal, a base, a base unit, a macro cell, a Node-B, an evolved Node B (eNB) , a gNB, a Home Node-B, a relay node, or a device, or described using other terminology used in the art. The BS may be generally part of a radio access network that may include one or more controllers communicably coupled to one or more corresponding BS (s) .

In an embodiment of the present application, the CN node (such as, the CN node 103 in FIG. 1 and the CN node 203 in FIG. 2) can be a mobility management entity (MME) or a serving gateway (S-GW) . In another embodiment of the present application, the CN node may include a mobility management function (AMF) or a user plane function (UPF) .

Currently, the UL or DL transmission following UL small data transmissions (SDT) without transitioning to RRC_CONNECTED state is supported. When there is an RRC connection between the UE and the BS, the UE is in the RRC_CONNECTED state. When UE is in RRC_INACTIVE state, it may be possible to send multiple UL and DL packets as part of the same SDT mechanism and without transitioning to RRC_CONNECTED on dedicated grant.

Generally, for a UE in inactive mode, it is possible to transmit UL small data to a BS in an initial random access procedure, such as, 2-step RACH procedure or 4-step RACH procedure. Furthermore, the UE may have subsequent UL small data to be transmitted, and the BS may have DL data to be transmitted. Therefore, it is desirable to provide a solution for the UE to perform the subsequent UL/DL data transmission when the UE is in inactive mode.

FIG. 3 illustrates a flow chart of a method for subsequent data transmission according to some embodiments of the present application. The method in FIG. 3 may be performed between a UE (such as, the UE 101 in FIG. 1 or the UE 201 in FIG. 2) which is in active mode or in idle mode and a BS (such as, the BS 102 in FIG. 1 or the BS 201a or the BS 201b in FIG. 2) . In the method of FIG. 3, the enhanced Msg. A and Msg. B in 2-step RACH procedure for subsequent DL/UL data transmission can be reused.

As shown in FIG. 3, in operation 301, a UE transmits a UL data (or called a first UL data, or an initial UL data) in Msg. A of 2-step RACH procedure.

After receiving the UL data from the UE, in order to schedule a subsequent UL data (or called a second UL data) transmission, in operation 302, the BS transmits resource for a dedicated preamble (or called dedicated preamble resource) for the subsequent UL data transmission. The subsequent UL data transmission may be UL small data or non-UL small data (such as, UL buffer status report (BSR) /release assistance information (RAI) ) . If there is DL data to be transmitted, the BS may also transmit the DL data along with the resource for a dedicated preamble.

The resource for the dedicated preamble for the subsequent UL data transmission may be time, frequency, or sequence resource. In an example, the resource for the dedicated preamble is transmitted in Msg. B of 2-step RACH procedure. In another example, the resource for the dedicated preamble is transmitted in subsequent UL or DL scheduling information. The subsequent UL or DL scheduling information may have the same or similar structure of Msg. B of 2-step RACH procedure. The subsequent UL or DL scheduling information could be downlink control information (DCI) for UL or DL scheduling, or RRC message or MAC CE including subsequent UL or DL scheduling information. The resource for the dedicated preamble could also be extended to include physical uplink share channel (PUSCH) resource associated to this dedicated preamble. The resource for the dedicated preamble could be at least one of the time/frequency resource and sequence/code resource.

The resource for the dedicated preamble may be transmitted via radio resource control (RRC) message, a media access control (MAC) control element (CE) , or physical layer signalling.

Furthermore, in an embodiment, the BS may also transmit indication information to indicate the resource for the dedicated preamble being applied for one shot, a plurality of shots, or an entire small data transmission procedure for the UE in inactive mode or idle mode. In another embodiment, a new timer can be configured so that the resource for the dedicated preamble can be applied when the timer is running or during a period.

In operation 303, the UE transmits the subsequent UL data transmission based on the dedicated preamble. After receiving the subsequent UL data transmission, in operation 304, the BS transmits DL response message.

Correspondingly, after transmitting the subsequent UL data transmission, the UE monitors the DL response message.

Since the subsequent UL or DL scheduling for the subsequent UL or DL transmission is UE-specific, the feedback from the network (the BS) is short and does not need to include feedback (s) to multiple UEs. Thus, after the UE transmits the subsequent UL data transmission based on the dedicated preamble, the UE may monitor the DL response message in a short-size window or when a new timer is running (before a new timer expired) . Correspondingly, the BS may transmit the DL response message in the short-size window or when the new timer is running. If there is DL data to be transmitted, the DL data can be multiplexed in the DL response message and transmitted to the UE. Furthermore, The DL response message may further include dedicated preamble resource for next UL data if needed.

If a successful DL response message is not received in the short-size window, or when the timer is running, or until the timer is expired, the UE will determine this UL data transmission as failed. And the UE will increase a number of failures of the 2-step RACH procedure based small data transmission by 1. And then the UE will initialize another 2-step RACH procedure for small data transmission if it is available. In an embodiment, the number of failures of 2-step RACH procedure is the number of a preamble transmission counter for small data transmission where the response for the UL data transmission is not received. The small data transmission includes the initial UL data in Msg. A and/or the subsequent UL data in the subsequent UL transmission for the UE in inactive mode or idle mode. The successful DL response message means the acknowledged information from the network (the BS) received by the UE.

A successful DL response message could be defined by at least one of the following cases:

If the cell-radio network temporary identifier (C-RNTI) MAC CE was included in MSGA and the PDCCH transmission is addressed to the C-RNTI, and UE receives this PDCCH transmission.

consider this DL response message reception successful;

If a downlink assignment has been received on the PDCCH for the C-RNTI and the received TB is successfully decoded:

5> if the MAC PDU contains the Absolute Timing Advance Command MAC CE subPDU:

6> process the received Timing Advance Command;

6> consider this Random Access Response reception successful;

6> stop the msgB-ResponseWindow;

6> consider this Random Access procedure successfully completed and finish the disassembly and demultiplexing of the MAC PDU.

If UE contention ID was included in Msg A and

2> If the common control channel (CCCH) service data unit (SDU) was included in MsgA and the PDCCH transmission is addressed to its TEMPORARY_C-RNTI:

3> if the MAC PDU is successfully decoded:

4> stop ra-ContentionResolutionTimer;

4> if the MAC PDU contains a UE Contention Resolution Identity MAC CE in the DL response message, and

4> if the UE Contention Resolution Identity in the MAC CE matches the CCCH SDU transmitted in MsgA:

5> consider this Contention Resolution successful and finish the disassembly and demultiplexing of the MAC PDU.

In above procedure, the Msg. A could be replaced by other UL information request with subsequent UL data transmission. The C-RNTI or TEMPORARY_C-RNTI could be replaced by the other X-RNTI for the subsequent UL or DL data transmission in UE inactive mode. X-RNTI could be C-RNTI defined in 2-step RACH procedure. Then a successful DL response message could be confirmed. Or a successful DL response message could be defined as: UE receives the DL response message scrambled by C-RNTI or X-RNTI successfully and the received TB is successfully decoded.

Furthermore, if the number of failures of the 2-step RACH based small data transmission procedure is greater than a threshold, the UE may transmit the subsequent UL data transmission by 4-step RACH procedure. In particular, the UE may transmit the subsequent UL data transmission based on the preamble of 4-step RACH procedure or the UL grant of 4-step RACH procedure which can be obtained from the DL response message. The 4-step RACH procedure may be for small data transmission for the UE in inactive mode or idle mode, or for non-small data transmission (such as, BSR and RAI transmission) for the UE in inactive mode or idle mode, or not for small data transmission.

Here, the threshold for transmitting a subsequent UL data transmission by 4-step RACH procedure for small data transmission for the UE in inactive mode or idle mode, or for non-small data transmission for the UE in inactive mode or idle mode, or not for small data transmission could be different. This means that the threshold is related to the specific 4-step RACH procedure. For example, the 4-step RACH procedure is for small data transmission for the UE in inactive mode or idle mode, or for non-small data transmission for the UE in inactive mode or idle mode, or not for small data transmission. This threshold may be configured to UE by RRC message, or SIB information, or MAC CE.

If the number of failure (s) of the 2-step RACH procedure for small data transmission for the UE in inactive mode or idle mode is greater than another threshold, the UE could initiate the 2-step RACH procedure for non-small data transmission for UE in active mode or idle mode. Then, the UE could report its BSR for small data transmission for UE in inactive mode or idle mode in MsgA of this the 2-step RACH procedure for non small data transmission for UE in active mode or idle mode. This threshold is configured to the UE by RRC message, or SIB information, or MAC CE.

Generally, if there is subsequent DL data transmission, it could be multiplexed in the DL response message (such as, Msg. B) .

In some cases, if the DL data cannot arrive timely when the BS is giving feedback to UL data, or if there is no UL data transmission, the subsequent DL data transmission cannot be multiplexed in the DL response message. Generally, a physical downlink control channel (PDCCH) configuration including control resource set (CORSET) and search space may be configured to the UE to receive the DL scheduling information, and the UE may receive the DL data based on the DL scheduling information. However, the DL data transmission in SDT may be sparse, so the signaling overhead for the monitoring on DL scheduling information in SDT should be further reduced.

In an embodiment, the UE may monitor the subsequent DL message (similarly to Msg. B) over the dedicated PDCCH resource, and the dedicated PDCCH resource is limited in the PDCCH based on a discontinuous reception (DRX) for SDT in inactive mode or idle mode. In another embodiment, the UE may receive the DL data based on the DL semi-persistent scheduling (SPS) configuration for SDT in inactive mode or idle mode.

As shown in FIG. 3, in operation 305, the BS may transmit a DL data based on DRX or DL SPS; and correspondingly, the UE may monitor and receive the DL data based on DRX or DL SPS.

In an embodiment, the BS may transmit to the UE one or more configuration of the DRX or the DL SPS for SDT in inactive mode or idle mode before 2-step RACH procedure. Correspondingly, the UE may receive and store the one or more configuration of the DRX or the DL SPS for SDT in inactive mode or idle mode before 2-step RACH procedure. The configuration of the DRX or the DL SPS can be per data radio bearer (DRB) or per traffic pattern.

In an example, DRX for SDT or DL SPS for SDT in inactive mode or idle mode may be configured and received in a radio resource control (RRC) release message or in a RRC message when the UE transitions from a connected mode to the inactive mode, when the UE transitions from the connected mode to the idle mode, or when the UE is in the inactive mode or the idle mode. The RRC release message or the RRC message enables the UE in the inactive mode or in the idle mode to transmit or receive data, or transmit or receive data in configured grant (CG) resources.

And then the UE may transmit indication information to indicate one configuration of the DRX or the DL SPS for small data transmission for the UE the inactive mode or the idle mode to the BS. The indicated configuration may be its preferable DRX or DL SPS. And then the BS may transmit one configuration of DRX or one or multiple dedicated configurations of DL SPS based on the indication information transmitted by the UE.

In another example, the BS may transmit one configuration of DRX or one or multiple dedicated configurations of DL SPS directly without the indication information from the UE.

In another embodiment, the BS may transmit one or more configuration of the DRX or the DL SPS for SDT in inactive mode or idle mode in the 2-step RACH procedure to the UE. Upon receiving the DRX or the DL SPS for SDT from the BS, the UE may trigger the DRX or the DL SPS for SDT.

If DRX is configured, the UE will start to monitor the PDCCH on duration time based on the configuration of the DRX, and perform the UL or DL data transmission based on DRX mechanism. The PDCCH resource including CORSET information and search space information could be configured in Msg. B of the 2-step RACH procedure.

When small data transmission procedure for the UE in inactive mode or idle mode is ended, the UE may store or release the configuration of the DRX or the DL SPS based on network indication or UE behavior.

FIG. 4 illustrates a flow chart of another method for subsequent data transmission according to some embodiments of the present application. The method in FIG. 4 may be performed between a UE (such as, the UE 101 in FIG. 1 or the UE 201 in FIG. 2) which is in active mode or in idle mode and a BS (such as, the BS 102 in FIG. 1 or the BS 201a or the BS 201b in FIG. 2) . In the method of FIG. 4, the enhanced Msg. 3 and Msg. 4 in 4-step RACH procedure for subsequent DL/UL data transmission can be reused.

As shown in FIG. 4, in operation 401, a UE transmits a UL data (or called a first UL data, or an initial UL data) in Msg. 3 of 4-step RACH procedure.

After receiving the UL data from the UE, in order to schedule a subsequent UL data (or called a second UL data) transmission, in operation 402, the BS transmits UL scheduling information for a subsequent UL transmission in Msg. 4 of 4-step RACH procedure. The UL scheduling information may be UL grant or a dedicated preamble in Msg. A of 2-step RACH procedure. The subsequent UL data transmission may be UL small data or non-UL small data (such as, UL BSR/RAI) .

In the case that the UL scheduling information is UL grant, the subsequent UL transmission is transmitted based on the UL grant.

In the case that the UL scheduling information is a dedicated preamble in Msg. A of 2-step RACH procedure, and the subsequent UL transmission is transmitted based on the dedicated preamble in Msg. A of 2-step RACH procedure. Generally, the 2-step RACH procedure is more efficient, thus the BS may make the UE transmit this the subsequent UL transmission by 2-step RACH procedure by transmitting the dedicated preamble of 2-step RACH procedure.

Furthermore, in an embodiment, the BS may also transmit indication information to indicate the UL grant or the dedicated preamble being applied for one shot, a plurality of shots, an entire small data transmission procedure for the UE in inactive mode or idle mode. In another embodiment, a new timer can be configured so that the UL grant or the dedicated preamble can be applied when the timer is running.

In operation 403, the UE transmits the subsequent UL data transmission based on the UL scheduling information, and then in operation 404, the UE monitors DL response message. Correspondingly, after receiving the subsequent UL data transmission, in operation 404, the BS transmits DL response message.

Since the subsequent UL scheduling information for the subsequent UL or DL transmission is UE-specific, the feedback from the network (the BS) can be short and does not need to include feedback (s) to multiple UEs. Thus, after the UE transmits the subsequent UL data transmission based on the dedicated preamble, the UE may monitor the DL response message in a short-size window or when a new timer is running (before a new timer expired) . Correspondingly, the BS may transmit the DL response message in the short-size window or when the new timer is running. If there is DL data to be transmitted, the DL data can be multiplexed in the DL response message and transmitted to the UE. Furthermore, the DL response message may further include dedicated preamble resource for next UL data if needed.

In another embodiment, in operation 402, the BS may transmit downlink (DL) assignment information for a subsequent DL transmission in Msg. 4 of 4-step RACH procedure, or the DL assignment information for the subsequent DL transmission may be transmitted along with the UL scheduling information for the subsequent UL transmission. Correspondingly, in operation 404, the BS may transmit the subsequent DL transmission based on the DL assignment information, or the subsequent DL transmission may be transmitted along with the DL response message. The DL assignment could be a MAC CE or RRC message. In an example, the DL assignment can be configured to being applied for one shot, a plurality of shots, an entire data transmission procedure, or when a timer is running. For example, the number of shot in a plurality of shots could be configured by network to UE.

Generally, if there is subsequent DL data transmission, it could be multiplexed in the DL response message.

In some cases, if the DL data cannot arrive timely when the BS is giving feedback to UL data, or if there is no UL data transmission, the subsequent DL data transmission cannot be multiplexed in the DL response message. Generally, a physical downlink control channel (PDCCH) configuration including CORSET and search space may be configured to the UE to receive the DL scheduling information, and the UE may receive the DL data based on the DL scheduling information. However, the DL data transmission in SDT may be sparse, so the signaling overhead for the monitoring on DL scheduling information in SDT should be further reduced.

In an embodiment, the UE may monitor the subsequent DL message (similarly to Msg. 4) over the dedicated PDCCH resource, and the dedicated PDCCH resource is limited in the PDCCH based on a DRX for SDT in inactive mode or idle mode. In another embodiment, the UE may receive the DL data based on the DL SPS configuration for SDT in inactive mode or idle mode.

As shown in FIG. 4, in operation 405, the BS may transmit a DL data based on DRX or DL SPS; and correspondingly, the UE may monitor and receive the DL data based on DRX or DL SPS.

In an embodiment, the BS may transmit one or more configuration of the DRX or the DL SPS for SDT in inactive mode or idle mode before 4-step RACH procedure to the UE. Correspondingly, the UE may receive and store the one or more configuration of the DRX or the DL SPS for SDT in inactive mode or idle mode before 4-step RACH procedure. The configuration of the DRX or the DL SPS can be per data radio bearer (DRB) or per traffic pattern.

The BS may transmit to the UE indication information to indicate the DRX or DL SPS being applied for one shot, a plurality of shots, an entire small data transmission procedure for the UE in inactive mode or idle mode, or when a timer is running, or until the small data transmission procedure is ended. The number of shot in a plurality of shots could by configured by network to the UE.

And then the UE may transmit to the BS indication information to indicate one configuration of the DRX or the DL SPS for small data transmission for the UE the inactive mode or the idle mode. The indicated configuration may be its preferable DRX or DL SPS. And then the BS may transmit one configuration of DRX or one or multiple dedicated configurations of DL SPS based on the indication information transmitted by the UE.

In another embodiment, the BS may transmit one or more configuration of the DRX or the DL SPS for SDT in inactive mode or idle mode in the 4-step RACH procedure to the UE. For example, the configuration of the DRX or the DL SPS may be received in the Msg. 2 or Msg. 4 in 4-step RACH procedure. Upon receiving the DRX or the DL SPS for SDT from the BS, the UE may trigger the DRX or the DL SPS for SDT.

If DRX is configured, the UE will start to monitor the PDCCH on duration time based on the configuration of the DRX, and perform the UL or DL data transmission based on DRX mechanism. The PDCCH resource including CORSET information and search space information could be configured in Msg. 4 of the 24-step RACH procedure.

In another embodiment, the configuration of discontinuous reception (DRX) or DL semi-persistent scheduling (SPS) may be independently from the 2-step RACH procedure or the 4-step RACH procedure as above described in FIG. 3 and FIG. 4.

In this embodiment, the UE may monitor and receive a DL data based on DRX or DL SPS. Correspondingly, the BS may transmit a DL data based on DRX or DL SPS; and correspondingly, the UE may monitor and receive the DL data based on DRX or DL SPS.

In an example, at least one configuration of DRX or DL SPS may be configured and received in a RRC release message or in a RRC message when the UE transitions from a connected mode to the inactive mode, when the UE transitions from a connected mode to the inactive mode, when the UE transitions from the connected mode to the idle mode, or when the UE is in the inactive mode or the idle mode, wherein the RRC release message or the RRC message enables the UE in the inactive mode or in the idle mode to transmit or receive data, or transmit or receive data in configured grant (CG) resources.

The UE may transmit indication information to indicate one configuration of the DRX or the DL SPS for small data transmission for the UE in inactive mode or idle mode; and/or receive indication information to indicate one configuration of the DRX or one or more dedicated configuration of the DL SPS.

The UE may receive configuration of the DRX or the DL SPS in CG based small data transmission procedure for UE in inactive mode or idle mode. The configuration of the DRX or the DL SPS is per data radio bearer (DRB) or per traffic pattern.

The UE may store or release the configuration of the DRX or the DL SPS based on network indication or UE behavior when small data transmission procedure for the UE in inactive mode or idle mode is ended.

FIG. 5 illustrates a flow chart of another method for subsequent data transmission according to some embodiments of the present application. The method in FIG. 5 may be performed between a UE (such as, the UE 101 in FIG. 1 or the UE 201 in FIG. 2) which is in active mode or in idle mode and a BS (such as, the BS 102 in FIG. 1 or the BS 201a or the BS 201b in FIG. 2) .

Usually, the 2-step RACH procedure has a higher priority compared to 4-step RACH procedure. The UE is able to apply the 2-step RACH procedure if a value for the channel quality (such as, the measured reference signal received power (RSRP) on serving cell) is greater than the threshold for 2-step RACH procedure.

In an embodiment, as shown in FIG. 5, in operation 501, the UE transmits a measurement result of a serving cell of the UE to the BS. After receiving the measurement result from the UE, in operation 502, the BS transmits indication information to indicate that the UE is enable or disable to apply 2-step RACH procedure for small data transmission for the UE in inactive mode or idle mode based on the measurement result. In another embodiment, the BS may transmit indication information to indicate UE report that UE is enable or disable to apply CG resource for small data transmission for the UE in inactive mode or idle mode.

In another embodiment, as shown in FIG. 5, in operation 501, the UE transmits indication information to indicate that the UE is enable or disable to apply 2-step RACH procedure for small data transmission for the UE in inactive mode or idle mode, and/or to indicate that the UE is enable or disable to apply CG resource for small data transmission for the UE in inactive mode or idle mode. The indication information may be MAC CE. After receiving the indication information from the UE, in operation 502, the BS transmits indication information to indicate the UE is able or disable to apply 2-step RACH procedure for small data transmission for the UE in inactive mode or idle mode, or indicate the UE is able or disable to apply CG resource for small data transmission for the UE in inactive mode or idle mode based on the indication information from the UE.

In yet another embodiment, the BS may transmit indication information to trigger the UE report its availability to 2-step RACH procedure for small data transmission for the UE in inactive mode or idle mode, after receiving the indication information from the BS, in operation 501, the UE may transmit a measurement result of a serving cell of the UE to the BS or indication information to indicate that the UE be able or disable to transition to 2-step RACH procedure for small data transmission for the UE in inactive mode or idle mode. After receiving the measurement result or the indication information from the UE, in operation 502, the BS transmits indication information to indicate that the UE is able or disable to apply 2-step RACH procedure for small data transmission for the UE in inactive mode or idle mode and/or to indicate that the UE is able or disable to apply CG resource for small data transmission for the UE in inactive mode or idle mode based on the indication information from the UE.

The indication information is transmitted in small data transmission procedure in UE inactive mode or idle mode. The indication information is transmitted in RRC message, system information block, or MAC CE.

After transition of the UE to 2-step RACH procedure from 4-step RACH procedure based on the indication information from the BS, radio network temporary identity (RNTI) for the UE in 4-step RACH procedure can be reused in 2-step RACH procedure.

In another embodiment, the transition from 2-step RACH procedure for small data transmission to 4-step RACH procedure for small data transmission or the 4-step RACH procedure for small data transmission to 2-step RACH procedure for non-small data transmission is independently from the dedicated preamble as described in the method of FIG. 3.

In this embodiment, the UE may initiate 4-step random access channel (RACH) procedure for small data transmission for the UE in inactive mode or idle mode, or initiate 2-step RACH procedure for non-small data transmission for the UE in inactive mode or idle mode, if PREAMBLE_TRANSMISSION_COUNTER for 2-step RACH procedure for small data transmission for the UE in inactive mode or idle mode is greater than a threshold, or equals to a threshold+1.

Correspondingly, the BS (the network) may receive a UL data by 4-step random access channel (RACH) procedure for small data transmission for the UE in inactive mode or idle mode, or by 2-step RACH procedure for non-small data transmission for the UE in inactive mode or idle mode, if PREAMBLE_TRANSMISSION_COUNTER for 2-step RACH procedure for small data transmission for the UE in inactive mode or idle mode is greater than a threshold, or equals to a threshold+1.

In this embodiment, the BS (the network) may transmit an indication to initiate the 4-step RACH procedure for small data transmission for the UE in inactive mode or idle mode, or to initiate the 2-step RACH procedure for non-small data transmission for the UE in inactive mode or idle mode, when PREAMBLE_TRANSMISSION_COUNTER for 2-step RACH procedure for small data transmission for the UE in inactive mode or idle mode is greater than the threshold, or equals to the threshold+1. In another embodiment, the UE may initiate the corresponding random access procedure based on the specified UE behavior, that is, the UE may directly initiate the 4-step RACH procedure for small data transmission for the UE in inactive mode or idle mode, or initiate the 2-step RACH procedure for non-small data transmission for the UE in inactive mode or idle mode, when PREAMBLE_TRANSMISSION_COUNTER for 2-step RACH procedure for small data transmission for the UE in inactive mode or idle mode is greater than the threshold, or equals to the threshold+1. The UE may receive the threshold by at least one of RRC message, system information blocks, or MAC CE.

In an embodiment of the present application, the UE may receive from the BS (the network) UL grant for Msg. 3 transmission with UL data from network if the UE initiates 4-step RACH procedure for small data transmission for the UE in inactive mode or idle mode.

In an embodiment of the present application, the UE may initiate 2-step RACH procedure for non-small data transmission for the UE in inactive mode or idle mode, if the UE is in 4-step RACH procedure for small data transmission for the UE in inactive mode or idle mode. Correspondingly, the BS may receive a UL data by 2-step RACH procedure for non-small data transmission for the UE in inactive mode or idle mode, if the UE is in 4-step RACH procedure for small data transmission for the UE in inactive mode or idle mode.

In an embodiment of the present application, the UE may initiate 2-step RACH procedure for non-small data transmission for the UE in inactive mode or idle mode based on specified UE behavior or network indication, if the UE initiates 4-step RACH procedure for small data transmission for the UE in inactive mode or idle mode, if the PREAMBLE_TRANSMISSION_COUNTER for 4-step RACH procedure for small data transmission for the UE in inactive mode or idle mode is greater than a threshold, or equals to a threshold+1. Correspondingly, the BS may receive a UL data by 2-step RACH procedure for non-small data transmission for the UE in inactive mode or idle mode based on specified UE behavior or network indication, if the UE initiates 4-step RACH procedure for small data transmission for the UE in inactive mode or idle mode, if the PREAMBLE_TRANSMISSION_COUNTER for 4-step RACH procedure for small data transmission for the UE in inactive mode or idle mode is greater than a threshold, or equals to a threshold+1.

For example, the threshold could be configured by network.

In this document, the subsequent UL data or a subsequent UL data could be the UL data transmitted in Msg. A, or Msg. 3 or CG based resource, or could be the UL data which has been transmitted by UE. In this document, the subsequent DL data or a subsequent DL data could be the DL data transmitted in Msg. B , or Msg. 4, or could be the DL data which has been transmitted by UE.

In this document, the data transmission or small data transmission may mean that a UE in inactive mode or idle mode could transmit the data to network, or receive the data from the network. The details could be as follows:

An inactive UE may have a CN connection in a cell (e.g., cell A) associated with its last serving BS (also referred to as "anchor BS" ) . However, in some scenarios, the inactive UE may perform data transmission via another cell (cell B) . The data transmission may include at least one of an uplink data transmission and downlink data transmission. For example, the inactive UE may initiate an uplink data transmission via cell B, establish a RAN connection with cell B, enter the connected mode, and then perform the data transmission. Or, the inactive UE may initiate an uplink data transmission via cell B and still stay in inactive mode in the data transmission procedure. An idle UE may act similarly.

After the completion of the data transmission, the inactive or idle UE may receive a suspend message or release message from cell B and then go back to the inactive or idle mode. Or, after the completion of the data transmission, the inactive or idle UE may receive a suspend message or release message from cell B and the UE still stay in inactive or idle mode in the data transmission procedure. In some embodiments of the present disclosure, the suspend message or release message is an RRC message. In some embodiments of the present disclosure, the data size in such data transmission may be no larger than the maximum transport block (TB) size that can be applied in one transmission, as defined in standard protocols. Small data transmission is one of such scenarios.

The embodiments of the present application can perform the subsequent UL/DL data transmission with less scheduling information.

FIG. 6 illustrates an apparatus according to some embodiments of the present application. In some embodiments of the present disclosure, the apparatus 600 may be the UE 101 as illustrated in FIG. 1, the UE 201 as illustrated in FIG. 2 or other embodiments of the present application.

As shown in FIG. 6, the apparatus 600 may include a receiver 601, a transmitter 603, a processer 605, and a non-transitory computer-readable medium 607. The non-transitory computer-readable medium 607 has computer executable instructions stored therein. The processer 605 is configured to be coupled to the non-transitory computer readable medium 607, the receiver 601, and the transmitter 603. It can be contemplated that the apparatus 600 may include more computer-readable mediums, receiver, transmitter and processors in some other embodiments of the present application according to practical requirements. In some embodiments of the present application, the receiver 601 and the transmitter 603 can be integrated into a single device, such as a transceiver. In certain embodiments, the apparatus 600 may further include an input device, a memory, and/or other components.

In some embodiments of the present application, the non-transitory computer-readable medium 607 may have stored thereon computer-executable instructions to cause the apparatus 600 to implement the method according to embodiments of the present application.

FIG. 7 illustrates another apparatus according to some embodiments of the present application. In some embodiments of the present disclosure, the apparatus 700 may be the BS 102 as illustrated in FIG. 1, the BS 202 as illustrated in FIG. 2 or other embodiments of the present application.

As shown in FIG. 7, the apparatus 700 may include a receiver 701, a transmitter 703, a processer 705, and a non-transitory computer-readable medium 707. The non-transitory computer-readable medium 707 has computer executable instructions stored therein. The processer 705 is configured to be coupled to the non-transitory computer readable medium 707, the receiver 701, and the transmitter 703. It can be contemplated that the apparatus 700 may include more computer-readable mediums, receiver, transmitter and processors in some other embodiments of the present application according to practical requirements. In some embodiments of the present application, the receiver 701 and the transmitter 703 are integrated into a single device, such as a transceiver. In certain embodiments, the apparatus 700 may further include an input device, a memory, and/or other components.

In some embodiments of the present application, the non-transitory computer-readable medium 707 may have stored thereon computer-executable instructions to cause the apparatus 700 to implement the method according to embodiments of the present application.

Persons skilled in the art should understand that as the technology develops and advances, the terminologies described in the present application may change, and should not affect or limit the principle and spirit of the present application.

Those having ordinary skill in the art would understand that the steps of a method described in connection with the aspects disclosed herein may be embodied directly in hardware, in a software module executed by a processor, or in a combination of the two. A software module may reside in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, a hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art. Additionally, in some aspects, the steps of a method may reside as one or any combination or set of codes and/or instructions on a non-transitory computer-readable medium, which may be incorporated into a computer program product.

While this disclosure has been described with specific embodiments thereof, it is evident that many alternatives, modifications, and variations may be apparent to those skilled in the art. For example, various components of the embodiments may be interchanged, added, or substituted in the other embodiments. Also, all of the elements of each figure are not necessary for operation of the disclosed embodiments. For example, one of ordinary skill in the art of the disclosed embodiments would be enabled to make and use the teachings of the disclosure by simply employing the elements of the independent claims. Accordingly, embodiments of the disclosure as set forth herein are intended to be illustrative, not limiting. Various changes may be made without departing from the spirit and scope of the disclosure.

In this document, the terms "comprises, " "comprising, " or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. An element proceeded by "a, " "an, " or the like does not, without more constraints, preclude the existence of additional identical elements in the process, method, article, or apparatus that comprises the element. Also, the term "another" is defined as at least a second or more. The terms "including, " "having, " and the like, as used herein, are defined as "comprising. "

Claims

A method, performed by a user equipment (UE) in inactive mode or in idle mode, comprising:

transmitting a first uplink (UL) data in Msg.A of 2-step random access channel (RACH) procedure;

receiving resource for a dedicated preamble for a subsequent UL data;

transmitting the subsequent UL data based on the dedicated preamble; and

monitoring downlink (DL) response message.
The method of Claim 1, wherein the resource for the dedicated preamble is received in Msg.B of 2-step RACH procedure or in subsequent UL or DL scheduling information.
The method of Claim 2, wherein the resource for the dedicated preamble is received via at least one of radio resource control (RRC) message, a media access control (MAC) control element (CE) , or physical layer signalling.
The method of Claim 1, further comprising: receiving indication information to indicate the resource for the dedicated preamble being applied for one shot, a plurality of shots, an entire small data transmission procedure for the UE in inactive mode or idle mode, when a first timer is running, or during a period.
The method of Claim 1, wherein the DL response message is monitored in a window or when a second timer is running.
The method of Claim 5, further comprising: if a successful DL response message is not received in the window, or when the second timer is running, or until the second timer is expired, increasing a number of failure (s) of the 2-step RACH based small data transmission procedure by 1.
The method of Claim 6, further comprising: if the number of failure (s) of the 2-step RACH based small data transmission procedure is greater than a threshold, transmitting a subsequent UL data by 4-step RACH procedure, wherein the 4-step RACH procedure is for small data transmission for the UE in inactive mode or idle mode, or for non-small data transmission for the UE in inactive mode or idle mode, or not for small data transmission.
The method of Claim 1, further comprising: receiving a DL data which is multiplexed in the DL response message.
The method of Claim 1, further comprising: monitoring and receiving a DL data based on discontinuous reception (DRX) or DL semi-persistent scheduling (SPS) .
A method, performed by a user equipment (UE) in inactive mode or in idle mode, comprising:

initiating 4-step random access channel (RACH) procedure for small data transmission for the UE in inactive mode or idle mode, or initiating 2-step RACH procedure for non-small data transmission for the UE in inactive mode or idle mode, if PREAMBLE_TRANSMISSION_COUNTER for 2-step RACH procedure for small data transmission for the UE in inactive mode or idle mode is greater than a threshold, or equals to a threshold+1.
The method of Claim 10, further comprising:

receiving an indication from network to initiate the 4-step RACH procedure for small data transmission for the UE in inactive mode or idle mode, or to initiate the 2-step RACH procedure for non-small data transmission for the UE in inactive mode or idle mode, when PREAMBLE_TRANSMISSION_COUNTER for 2-step RACH procedure for small data transmission for the UE in inactive mode or idle mode is greater than the threshold, or equals to the threshold+1; or

directly initiating the 4-step RACH procedure for small data transmission for the UE in inactive mode or idle mode, or initiating the 2-step RACH procedure for non-small data transmission for the UE in inactive mode or idle mode, when PREAMBLE_TRANSMISSION_COUNTER for 2-step RACH procedure for small data transmission for the UE in inactive mode or idle mode is greater than the threshold, or equals to the threshold+1.
The method of Claim 10, wherein the threshold is received by at least one of RRC message, system information blocks, or MAC CE.
The method of Claim 10, further comprising:

receiving UL grant for Msg.3 transmission with UL data from network if the UE initiates 4-step RACH procedure for small data transmission for the UE in inactive mode or idle mode.
The method of Claim 10, further comprising:

initiating 2-step RACH procedure for non-small data transmission for the UE in inactive mode or idle mode, if the UE is in 4-step RACH procedure for small data transmission for the UE in inactive mode or idle mode.
The method of Claim 10, further comprising:

initiating 2-step RACH procedure for non-small data transmission for the UE in inactive mode or idle mode based on specified UE behavior or network indication, if the UE initiates 4-step RACH procedure for small data transmission for the UE in inactive mode or idle mode, if the PREAMBLE_TRANSMISSION_COUNTER for 4-step RACH procedure for small data transmission for the UE in inactive mode or idle mode is greater than a threshold, or equals to a threshold+1.