Method and related device for small data transmission in inactive state

Abstract

A method and related device for small data transmission (SDT) in RRC_INACTIVE state are provided. The method comprises: receiving a radio resource control (RRC) release message for providing an SDT configuration, and a first time advance (TA) command sent together with the RRC release message; applying the first TA command upon receiving the RRC release message; and starting or restarting a timing alignment timer (TAT) upon receiving the first TA command sent together with the RRC release message, to maintain uplink (UL) timing alignment in an SDT procedure in RRC_INACTIVE state. By using the method, UL synchronization / timing maintenance in RRC_INACTIVE state is achieved.

Description

Technical Field

[0001] This application relates to the field of communication system technology, and in particular to a method and related equipment for small data transmission (SDT) in an RRC_INACTIVE state. Background Technology

[0002] Communication systems and networks have evolved into broadband mobile systems. In cellular wireless communication systems developed by the Third Generation Partnership Project (3GPP), User Equipment (UE) connects to the Radio Access Network (RAN) via a radio link. The RAN comprises a set of Base Stations (BSs) that provide radio links to UEs located within the cell coverage area of ​​the base stations, and includes an interface to the Core Network (CN), which controls the overall network. It can be understood that the RAN and CN each perform corresponding functions relevant to the entire network. 3GPP has developed the so-called Long Term Evolution (LTE) system, namely the Evolved Universal Mobile Communications System Territorial Radio Point Access Network (E-UTRAN), for mobile access networks supported by one or more macro cells, called eNodeBs or eNBs (evolved NodeBs). Recently, LTE has further evolved into the so-called 5G or New Radio (NR) system, in which one or more cells are supported by base stations called gNBs.

[0003] In LTE, if a UE is inactive for a period of time, the network can command the UE to enter the RRC_IDLE state to reduce UE power consumption. Whenever the UE needs to perform some activity, it needs to transition from the RRC_IDLE state to the RRC_CONNECTED state. In current mobile communication applications, small amounts of data must be transmitted frequently, so frequent transitions between idle and connected states increase network signaling burden and latency. Therefore, 5G NR defines a new state called RRC_INACTIVE to reduce the network signaling burden and latency caused by transitioning to the RRC_CONNECTED state. In NR, when an RRC connection is established, the UE is in the RRC_CONNECTED state, and when the RRC connection is suspended, the UE is in the RRC_INACTIVE state. If neither of these conditions applies, the UE is in the RRC_IDLE state, meaning no RRC connection has been established. More specifically, in the RRC_INACTIVE state, the UE Access Stratum (AS) context is stored on both the UE and network sides, thereby maintaining the connection with the core network (i.e., the UE remains in the CM-CONNECTED state (CM stands for Connection Management) while disconnecting from the radio access network (RAN). The network can contact the inactive UE via RAN or CN paging messages.

[0004] Random Access (RA) procedures can be classified into Contention-Free Random Access (CFRA) and Contention-Based Random Access (CBRA). For CFRA, the gNB allocates a preamble, known as a dedicated random access preamble. This dedicated preamble can be provided to the UE via RRC signaling (preamble allocation can be configured within the RRC message). Therefore, the UE can transmit this dedicated preamble in a contention-free manner. For CBRA, the UE randomly selects a preamble from a preamble group shared with other UEs. This means there is a potential risk that a UE might choose the same preamble as another UE, potentially leading to a conflict. The gNB uses a contention-based resolution mechanism to handle access requests; in this process, the result is random, and not all random access attempts will succeed.

[0005] Contention-free or contention-based RA procedures can be either a four-step or a two-step procedure. Taking a four-step contention-based RA procedure as an example, the UE sends a contention-based PRACH preamble, also known as MSG1. Upon detecting this preamble, the gNB responds to the UE with a random-access response (RAR), also known as MSG2. This RAR includes uplink grants used to schedule transmissions from the UE on the Physical Uplink Shared Channel (PUSCH), called MSG3. In response to this RAR, the UE sends MSG3, which includes an ID for contention resolution. Upon receiving MSG3, the network sends a contention resolution message with this contention resolution ID, also known as MSG4. The UE receives MSG4, and if it has found its contention resolution ID, it sends an acknowledgment on the Physical Uplink Control Channel (PUCCH), thus completing the four-step random access procedure.

[0006] The two-step RA procedure is designed to reduce latency and control signaling overhead by using a single round-trip cycle between the UE and the base station. This is achieved by combining the preamble (MSG1) and the scheduled PUSCH transmission (MSG3) into a single message from the UE to the gNB, known as MSGA, and combining the random access response (MSG2) and the contention resolution message (MSG4) into a single message (MSGB) from the gNB to the UE. Both the two-step and four-step procedures can be applied to CFRA when a dedicated preamble is provided to the UE.

[0007] Prior to 3GPP Release 16, data transmission was only supported in the RRC_CONNECTED state. When the UE remained in the RRC_INACTIVE state and UL data arrived in the TX buffer, the UE had to restore the connection (i.e., enter the RRC_CONNECTED state) to transmit data. Establishing a connection and then releasing it to the RRC_INACTIVE state occurred with every data transmission. However, for a small number of infrequent data packets, this resulted in unnecessary power consumption and signaling overhead.

[0008] On the other hand, the UE has a configurable timing alignment timer, which controls how long it takes for the UE's uplink timing to be considered aligned with the relevant cell. Currently, as specified in the 3GPP specification, the timing alignment timer configuration is only valid and used in the RRC_CONNECTED state. When the UE enters the RRC_INACTIVE state, the timing alignment timer stops whenever the Media Access Control (MAC) is reset. As a result, the UE perceives that uplink synchronization has been disrupted. Therefore, when a small amount of data can be transmitted in the RRC_INACTIVE state, some operations need to be designed to manage UL time alignment. At the same time, for small data transmissions, timing misalignments should be corrected in the RRC_INACTIVE state, rather than transitioning to the RRC_CONNECTED state. Summary of the Invention

[0009] One objective of this application is to provide a method and related equipment (e.g., user equipment (UE) and / or base station (BS)) for small data transmission (SDT) in RRC_INACTIVE state, which can solve the problems in the prior art, achieve UL synchronization / timing maintenance, improve resource utilization efficiency, improve power consumption and signaling overhead, and / or provide good communication performance.

[0010] In a first aspect of this application, a method for small data transmission (SDT) in RRC_INACTIVE state is provided, which is performed by user equipment (UE) in a network. The method includes: receiving a Radio Resource Control (RRC) release message for providing SDT configuration, and a first timing advance (TA) command sent together with the RRC release message; applying the first TA command upon receiving the RRC release message; and starting or restarting a Timing Alignment Timer (TAT) upon receiving the first TA command sent together with the RRC release message, so as to maintain uplink (UL) timing alignment during SDT in RRC_INACTIVE state.

[0011] In a second aspect of this application, a method for small data transmission (SDT) in RRC_INACTIVE state is provided, which is performed by a base station (BS) in a network. The method includes: sending a Radio Resource Control (RRC) release message for providing SDT configuration and a first timing advance (TA) command sent together with the RRC release message to a user equipment (UE); expecting the UE to apply the first TA command upon receiving the RRC release message; and expecting the UE to start or restart a timing alignment timer (TAT) upon receiving the first TA command sent together with the RRC release message, so as to maintain uplink (UL) timing alignment during SDT in RRC_INACTIVE state.

[0012] In a third aspect of this application, a user equipment includes a memory, a transceiver, and a processor coupled to the memory and the transceiver, the processor being configured to call and execute program instructions stored in the memory to perform the method of transmitting small amounts of data in the RRC_INACTIVE state described above.

[0013] In a fourth aspect of this application, a base station includes a memory, a transceiver, and a processor coupled to the memory and the transceiver. The processor is configured to call and run program instructions stored in the memory to perform the method of transmitting a small amount of data in the RRC_INACTIVE state described above.

[0014] In a fifth aspect of this application, a non-transitory machine-readable storage medium is provided, having stored instructions that, when executed by a computer, cause the computer to perform the method described above.

[0015] In a sixth aspect of this application, a chip includes a processor configured to invoke and run a computer program stored in a memory, causing a device on which the chip is installed to perform the above-described method. In a seventh aspect of this application, a computer-readable storage medium is provided having a computer program stored thereon, wherein the computer program causes a computer to perform the above-described method. In an eighth aspect of this application, a computer program product includes a computer program, wherein the computer program causes a computer to perform the above-described method. In a ninth aspect of this application, a computer program is provided, wherein the computer program causes a computer to perform the above-described method. Attached Figure Description

[0016] To more clearly illustrate the embodiments of this application or related technologies, the following figures will be described in conjunction with the embodiments, and will be briefly introduced below. It is obvious that these figures merely represent some embodiments of this application, and those skilled in the art can derive other figures based on these figures without making any presuppositions.

[0017] Figure 1A A schematic diagram of a communication control system according to an embodiment of this application is shown.

[0018] Figure 1B A block diagram showing a user equipment and base station performing wireless communication in a communication control system according to an embodiment of this application. Figure 2 A schematic diagram showing an overview of the RRC state transitions of the UE in NR. Figure 3A This application illustrates a method for small data transfer (SDT) in the RRC_INACTIVE state according to one aspect of the application. Figure 3B This application illustrates a method for small data transfer (SDT) in the RRC_INACTIVE state according to another aspect of the application. Figure 3C This application illustrates a method for small data transfer (SDT) in the RRC_INACTIVE state according to another aspect of the application. Figure 4A This shows an example of the SDT time advance command MAC CE according to this application. Figure 4B This shows another example of the SDT time advance command MAC CE according to this application. Figure 5A This shows an example of a continuing SDT MAC CE according to this application. Figure 5B This paper shows an example of an LCG-based SDT MAC CE according to this application. Figure 5C This shows another example of an LCG-based SDT MAC CE according to this application. Figure 5D This shows an example of a TAG-based connection SDT MAC CE according to this application. Figure 5E This shows another example of a TAG-based SDT MAC CE according to this application. Figure 6 A flowchart showing a method for transmitting a small amount of data in the RRC_INACTIVE state according to a first embodiment of this application. Figure 7A flowchart showing a method for transmitting a small amount of data in the RRC_INACTIVE state according to a second embodiment of this application. Figure 8 A flowchart showing a method for transmitting a small amount of data in the RRC_INACTIVE state according to a third embodiment of this application is displayed. Figure 9 A flowchart showing a method for transmitting small amounts of data in the RRC_INACTIVE state according to a fourth embodiment of this application. Figure 10 A flowchart showing a method for transmitting a small amount of data in the RRC_INACTIVE state according to a fifth embodiment of this application. Figure 11 A flowchart showing a method for transmitting small amounts of data in the RRC_INACTIVE state according to a sixth embodiment of this application. Figure 12 A flowchart showing a method for transmitting small amounts of data in the RRC_INACTIVE state according to the seventh embodiment of this application. Figure 13 A flowchart showing a method for transmitting a small amount of data in the RRC_INACTIVE state according to the eighth embodiment of this application is displayed. Figure 14 A flowchart showing a method for transmitting small amounts of data in the RRC_INACTIVE state according to the ninth embodiment of this application is displayed. Figure 15 A flowchart showing a method for transmitting small amounts of data in the RRC_INACTIVE state according to the tenth embodiment of this application is displayed. Figure 16 A flowchart showing a method for transmitting small amounts of data in the RRC_INACTIVE state according to the eleventh embodiment of this application is displayed. Figure 17 A flowchart showing a method for transmitting small amounts of data in the RRC_INACTIVE state according to the twelfth embodiment of this application is displayed. Figure 18 A flowchart showing a method for transmitting small amounts of data in the RRC_INACTIVE state according to the thirteenth embodiment of this application is displayed. Figure 19 A flowchart showing a method for transmitting small amounts of data in the RRC_INACTIVE state according to the fourteenth embodiment of this application is displayed. Detailed Implementation The embodiments of this application will now be described in detail below with reference to the accompanying drawings, focusing on their technical solutions, structural features, achieved objectives, and effects. Specifically, the terminology used in the embodiments of this application is only used to describe certain embodiments and is not intended to limit the content of this application.

[0019] In this article, " / " should be interpreted as "and / or".

[0020] Figure 1A and Figure 1B A schematic diagram and a functional block diagram of the communication control system 1 according to the present invention are shown respectively. The communication control system 1 includes user equipment (UE) 10 and base station 20, which can communicate with each other wirelessly or via wired means. Base station 20 and next-generation core network 30 can also communicate with each other wirelessly or via wired means. When the communication control system 1 conforms to the New Radio (NR) standard of the 3rd Generation Partnership Project (3GPP), the next-generation core network (5GCN) 30 is a back-end service network system and may include Access and Mobility Management Function (AMF), User Plane Function (UPF), and Session Management Function (SMF).

[0021] User equipment 10 may be a device that does not support NPN or a device that supports non-public network (NPN), but the present invention is not limited thereto. User equipment 10 includes a transceiver 12 and a processor 14 electrically connected to each other. Base station 20 includes a transceiver 22 and a processor 24 electrically connected to each other. The transceiver 12 of user equipment 10 is used to transmit signals to base station 20, and the processor 24 of base station 20 processes the signals. The transceiver 22 of base station 20 is used to transmit signals to user equipment 10, and the processor 14 of user equipment 10 processes the signals. In this way, user equipment 10 and base station 20 communicate with each other. Figure 2This provides an overview of the Radio Resource Control (RRC) state transitions of a UE in NR. When an RRC connection has been established, the UE is either in the RRC_CONNECTED state or the RRC_INACTIVE state. In the RRC_INACTIVE state, the network and UE store the UE's inactive AS context and perform small data transmission (SDT) in a low-power manner. For SDT in the RRC_INACTIVE state, the UE receives an RRCRelease with a pause or suspend configuration (e.g., SDT configuration) and resumes the RRC connection if necessary. If this is not the case, i.e., the RRC connection is released, the UE is in the RRC_IDLE state. This invention proposes a time-aligned small amount of data transmission (SDT) procedure for inactive UEs. The SDT procedure in the RRC_INACTIVE state has the following three types: Two-step RACH-based SDT: UL and DL data are multiplexed with MSGA and MSGB respectively. For SDT performed in RRC_INACTIVE state, contention-based and / or contention-free RACH can be supported.

[0022] Four-step RACH-based SDT: UL and DL data are multiplexed with MSG3 and MSG4 respectively. For SDT performed in RRC_INACTIVE state, contention-based and / or contention-free RACH can be supported.

[0023] SDT based on Configuration Grant (CG): UL / DL data is transferred on pre-configured resources based on the CG-based SDT configuration and the DL allocation configuration for SDT. This application provides a method for managed uplink (UL) time alignment for UEs in the RRC_INACTIVE state. The invention proposes a Time Alignment (SDT) procedure for inactive UEs. According to one aspect of the invention, control information from the network (e.g., SDT time advance command MAC CE) is used to control the amount of time adjustment the UE needs to apply. According to another aspect of the invention, auxiliary information from the UE (e.g., connection SDT indication) is used to indicate what SDT resources the UE needs. This invention benefits network resource utilization efficiency and UE energy efficiency. Figure 3AThis application illustrates a method 310 for small data transfer (SDT) in the RRC_INACTIVE state according to one aspect of the present application. Method 310 is performed by user equipment (UE) in the network. Method 310 may include the following steps: In block 312, a base station or network transmits, and the UE receives, a Radio Resource Control (RRC) release message for providing SDT configuration, and a timing advance (TA) command transmitted along with the RRC release message. In block 314, the UE applies, and the base station or network expects the UE to apply the TA command upon receiving the RRC release message. In block 316, the UE starts or restarts, and the base station or network expects the UE to start or restart a Timing Alignment Timer (TAT) upon receiving the TA command transmitted along with the RRC release message, to maintain uplink (UL) timing alignment during SDT in the RRC_INACTIVE state. This can solve the problems in existing technologies, achieve UL synchronization / timing maintenance, improve resource utilization efficiency, reduce power consumption and signaling overhead, and / or provide good communication performance.

[0024] In this aspect of the application, the UE receives an RRC release message (e.g., RRCRelease) and a TA command sent along with the RRC release message from the network. For example, when the UE receives the RRC release message for suspending or halting the RRC connection, the UE can transition from the RRC_CONNECTED state to the RRC_INACTIVE state. The RRC release message also includes SDT configuration, which is necessary for the UE to perform SDT in the RRC_INACTIVE state. The TA command indicates an index value used to control the amount of time adjustment that the UE needs to apply when performing SDT in the RRC_INACTIVE state. Upon receiving the RRC release message and the TA command, the UE applies the TA command to time align with the network. Once the UE receives the TA command, the UE also starts or restarts a timing alignment timer to maintain uplink (UL) time alignment when performing SDT in the RRC_INACTIVE state. Time alignment is achieved between the UE and the network in the RRC_INACTIVE state while the TAT is running and has not expired. Therefore, UL synchronization of SDT in the RRC_INACTIVE state is achieved.

[0025] Figure 3BThis application illustrates a method 320 for small data transfer (SDT) in the RRC_INACTIVE state according to another aspect of the present application. Method 320 is performed by user equipment (UE) in the network. Method 320 may include the following steps: In block 322, the network sends and the UE receives an SDT configuration for configuring SDT UL authorization, and the SDT configuration includes an SDT threshold. In block 324, based on the SDT threshold, the UE determines, and the network expects the UE to determine, which type of SDT procedure to apply in the RRC_INACTIVE state. In block 326, the UE receives a Timing Advance (TA) command from the network. Upon receiving the TA command in the RRC_INACTIVE state, the UE applies, and the network expects the UE to apply, the TA command, and starts or restarts a Timing Alignment Timer (TAT) to maintain uplink (UL) timing alignment during SDT in the RRC_INACTIVE state. In block 328, the UE and the network expect the UE to follow the SDT procedure determined by the initiated or restarted TAT application. Even if the TAT expires, the SDT configuration or the SDT UL authorization will be retained. This addresses problems in the prior art, enabling UL synchronization / timing maintenance, improving resource utilization efficiency, reducing power consumption and signaling overhead, and / or providing good communication performance.

[0026] In this aspect of the application, an SDT configuration including an SDT threshold is sent from the network and received by the UE. This SDT configuration is used to configure the SDT UL authorization and may be included, for example, in an RRC release message (e.g., RRCRelease). When the UE receives the RRC release message for suspending or ending the RRC connection, the UE can transition from the RRC_CONNECTED state to the RRC_INACTIVE state. In this method, the SDT configuration and / or the SDT UL authorization will be maintained even if the TAT expires. For example, when the UE transitions from the RRC_CONNECTED state to the RRC_INACTIVE state, the SDT configuration or the SDT UL authorization will still be maintained even if the TAT expires during this period. The UE can determine which type of SDT procedure to apply in the RRC_INACTIVE state based on the SDT threshold in the SDT configuration. This SDT threshold can be a data volume threshold, representing the amount of data to be transmitted in the RRC_INACTIVE state. The type of SDT procedure can include Configuration Grant (CG) based SDT and Random Access Channel (RACH) based SDT (e.g., two-step RACH-based SDT, four-step RACH-based SDT). The UE receives a TA command from the BS or network. This TA command can be transmitted, for example, along with the RRC release message before the UE transitions to the RRC_INACTIVE state. Alternatively, the TA command can be received by the UE while it is in the RRC_INACTIVE state. Upon receiving the TA command, the UE applies it to apply the time adjustment amounts required for SDT in the RRC_INACTIVE state. In addition, the UE starts or restarts a Timing Alignment Timer (TAT) to maintain uplink (UL) time alignment during SDT in RRC_INACTIVE state. After UL time alignment with the network, the UE applies the determined type of SDT procedure. For example, if CG-based SDT is determined, the CG-based SDT procedure is executed. Thus, UL synchronization of SDT in RRC_INACTIVE state is achieved.

[0027] Figure 3CThis invention discloses a method 330 for small data transmission (SDT) in the RRC_INACTIVE state according to another aspect of this application. Method 330 is performed by user equipment (UE) in the network. Method 330 may include the following steps: In block 332, the network sends and the UE receives an SDT Timing Advance Command (Timing Advance Command) Media Access Control (MAC) Control Element (CE) from the network. In block 334, the UE initiates or restarts a Timing Alignment Timer (TAT) that the network expects the UE to initiate or restart upon receiving the Timing Advance Command carried by the SDT Timing Advance Command MAC CE, in order to maintain uplink (UL) timing alignment during SDT in the RRC_INACTIVE state. In block 336, when UL data arrives at the UE TX buffer, the UE sends and the network receives the SDT while the TAT is running. This can solve the problems in existing technologies, achieve UL synchronization / timing maintenance, improve resource utilization efficiency, reduce power consumption and signaling overhead, and / or provide good communication performance.

[0028] In this aspect of the application, the Time Advance (TA) command can be carried by the SDT Time Advance Command MAC CE. This TA command indicates an index value used to control the amount of time adjustment the UE needs to apply when performing SDT in RRC_INACTIVE state. Upon receiving this TA command, the UE initiates or restarts the TAT to maintain uplink (UL) time alignment during SDT in RRC_INACTIVE state. While the TAT is running and has not expired, time alignment is achieved between the UE and the network in RRC_INACTIVE state. When UL data arrives at the UE's TX buffer, the UE can send SDT to the BS or network while the TAT is running. Therefore, UL synchronization of SDT in RRC_INACTIVE state is achieved.

[0029] In some embodiments, the SDT configuration is configured / updated via RRC signaling for SDT UL authorization. In some cases, the SDT configuration configured / updated via system information is a public / UE-specific SDT configuration, and the SDT UL authorization is an SDT UL authorization shared among UEs in the RRC_INACTIVE state. In some embodiments, the UE may be configured with the SDT configuration via system information for SDT UL authorization. In some cases, the SDT configuration configured via RRC signaling is a UE-specific SDT configuration, and the SDT UL authorization is an SDT UL authorization dedicated to one or more UEs in the RRC_INACTIVE state. In some embodiments, the SDT configuration includes an SDT threshold, which the UE uses to determine which SDT type to apply in the RRC_INACTIVE state. In some embodiments, the SDT configuration includes an SDT reference signal received power (RSRP) threshold, which the UE uses to determine whether to activate the SDT UL authorization in the RRC_INACTIVE state. In some embodiments, the SDT configuration includes an SDTPRACCH configuration, which indicates one or more specific preamble groups for RACH-based SDT procedures in the RRC_INACTIVE state. In some cases, the one or more specific preamble groups used for SDT in the RRC_INACTIVE state are used to notify the network to perform SDT in the RRC_INACTIVE state, such that SDT continuation UL authorization is assigned or activated, or to notify the network of relevant SDT data volume, or SDT traffic statistics or patterns. From a network perspective, these UL-authorized resources can be shared or UE-specific, depending on the network implementation. For connected SDTs, the scrambling initialization of the PDSCH associated with the PDCCH is used in the RRC_INACTIVE state by the 5G NR Radio Network Temporary Identifier, such as: C-RNTI (C for "cell"), SDT-RNTI, I-RNTI (I for "inactive"), and P-RNTI (P for "paging"). For dedicated and / or shared connected SDT procedures, the UE can be configured to decode the PDCCH with a CRC formed by scrambling with C-RNTI, SDT-RNTI, I-RNTI, and / or P-RNTI. The UE should decode the PDCCH and the corresponding PDSCH based on the 5G NR RNTI. For SDT UL authorization shared within a UE, the network can broadcast / unicast common / UE-specific SDT configurations (e.g., supported SDT types, SDT priorities, common / UE-specific SDT search spaces, common SDT thresholds, common SDT_RSRP thresholds, SDT paging configurations and search spaces, RACH-based SDT configurations, SDT PRACH configurations, etc.) through system information (e.g., SIB2, on-demand SI). This shared SDT UL authorization is a shared resource among multiple UEs in the RRC_CONNECTED / RRC_INACTIVE state. For UE-specific SDTs, the network can unicast UE-specific SDT configurations (e.g., supported SDT types, SDT priorities, UE-specific SDT thresholds, UE-specific SDT_RSRP thresholds, CG-based SDT configurations, SDT DL allocation configurations, SDT ran-Paging Cycles, I-RNTIs, SDT release reasons, etc.) via RRC signaling (e.g., RRC Release). This dedicated SDT UL authorization is a private resource among one or more UEs in the RRC_INACTIVE state. If a UE is configured, it can use that UE-specific SDT configuration; otherwise, it uses the common SDT configuration. For public / UE-specific SDT configurations transmitted in system information, the network can configure supported SDT types, such as two-step RACH-based SDT, four-step RACH-based SDT, and CG-based SDT. SDT priority is used to distinguish SDT transmission priorities. A public / UE-specific SDT search space is assigned to UEs that support SDT, and a public / UE-specific PDCCH with scheduling-related shared / dedicated UL SDT authorizations is allocated within it. A public SDT threshold is given to the UE to determine whether to apply the CG-SDT procedure to the shared SDT UL authorization. A public SDT_RSRP threshold is given to the UE to determine whether to activate the shared SDT UL authorization in the RRC_INACTIVE state. SDT paging configuration and search space are used for RRC SDT response and time alignment during SDT execution. Paging timing, paging cycle, and paging reason / access type are configured for SDT in the RRC_INACTIVE state. In some cases, associated DL SDTs are multiplexed with SDT paging messages on the PDSCH. Then, the UE decodes the content of the SDT paging message (e.g., paging reason, access type) to execute the relevant SDT procedure. RACH-based SDT configuration includes the configuration of public / UE-specific random access parameters that the UE uses for contention-based and contention-free RACH SDT procedures in the RRC_INACTIVE state. The SDT PRACH configuration indicates a specific preamble index / group used for contention-based and contention-free RACH SDT procedures in the RRC_INACTIVE state. In some cases, a specific preamble group for the SDT in the RRC_INACTIVE state can be used to inform the network of the SDT connection in the RRC_INACTIVE state so that the connection's UL authorization can be allocated / activated for the SDT procedure. In other cases, when no SDT threshold is configured for RACH-based SDT, a specific preamble group for the SDT in the RRC_INACTIVE state can be used to inform the network of the relevant SDT data volume or SDT traffic statistics / patterns. For the UE, if a specific preamble group is configured for SDT in the RRC_INACTIVE state, and if the UE expects the connected SDT or needs to transmit further SDT data, that specific preamble group should be selected. Then, the UL license can be assigned / activated for the SDT that follows in the RRC_INACTIVE state.

[0030] For UE-specific SDT configurations transmitted in RRC signaling, the network can configure supported SDT types, such as two-step RACH-based SDT, four-step RACH-based SDT, and CG-based SDT. SDT priority is used to distinguish the transmission priority of SDTs in the RRC_INACTIVE state. UE-specific SDT thresholds are given to the UE to determine whether to apply the CG-SDT procedure to the dedicated SDT UL authorization. UE-specific SDT_RSRP thresholds are given to the UE to determine whether to activate the dedicated SDT UL authorization in the RRC_INACTIVE state. CG-based SDT configurations include CG resource allocation and periodicity for single or multiple SDTs in the RRC_INACTIVE state. DL allocation configurations for SDTs are configured in response to the associated CG-based UL SDTs so that the UE can decode the corresponding PDCCH and PDSCH. The SDT ran-PagingCycle indicates the UE-specific period for SDT paging in the RRC_INACTIVE state. SDT paging is neither RAN-specific nor CN-specific, but cell-specific, and has low paging overhead. Furthermore, when the UE transitions from the RRC_CONNECTED state to the RRC_INACTIVE state, an I-RNTI can be assigned to the UE as part of the suspendConfig, thus determining whether the UE is in the RRC_INACTIVE state. Regarding SDT, the release reason indicates that, considering the UE's power consumption, the network anticipates receiving the SDT in the RRC_INACTIVE state.

[0031] From the UE's perspective, a small amount of UL data can be transmitted to the network in the RRC_INACTIVE state via the SDT procedure. The SDT threshold transmitted in system information or other RRC configuration messages is used by the UE to determine which type of SDT procedure to use. On the other hand, when the channel quality is below the SDT_RSRP threshold, the SDT procedure should be deactivated and the UE should transition to the RRC_CONNECTED state for normal data transmission. When the UE's data volume exceeds this SDT threshold, the UE will enter the RRC_CONNECTED state for normal data transmission. In certain situations (e.g., bursty data such as images, periodic data reports such as location reports), subsequent small amounts of UL / DL data transmission following the initial UL SDT should be supported without transitioning to the RRC_CONNECTED state.

[0032] When a two-step RACH-based SDT is applied based on the SDT threshold, the preamble, RRC SDT request (e.g., RRC Resume Request), and a small amount of UL data packets are multiplexed in the MSGA. The RRC SDT response (e.g., RRC Resume Request, SDTPaging) and an optional small amount of DL data packets can be multiplexed in the MSGB. The subsequent UL / DL data packets can be transmitted after the MSGA / MSGB. If the MSGA transmission fails, an inactive UE can execute a fallback four-step RACH-based SDT procedure. When a four-step RACH-based SDT is applied based on the SDT threshold, the RRC SDT request (e.g., RRC Resume Request) and a small amount of UL data packets are multiplexed in MSG3. The RRC SDT response (e.g., RRC Resume Request, SDTPaging) and an optional small amount of DL data packets can be multiplexed in MSG4. The subsequent UL / DL data packets can be transmitted after MSG3 / MSG4. When CG-based SDT is applied based on the SDT threshold, the configured authorized resources are dedicated to inactive UEs for small-scale UL data transmission. In response to UL data transmission, optional small-scale DL packets can be multiplexed into RRC SDT responses (e.g., RRC Release, SDT paging) sent to inactive UEs. For UL time alignment, the SDT time advance command and SDT timing alignment timer should be maintained in the RRC_INACTIVE state to ensure SDT success. For consecutive SDTs, there should be a consecutive SDT indication, which is transmitted / multiplexed with PUCCH or PUSCH resources in RACH-based or CG-based SDTs. In some embodiments, when a TA command is received in the RRC_INACTIVE state, the TAT is restarted. In some cases, the TA command is carried by a Media Access Control (MAC) Control Element (CE). In some cases, the TA command is sent along with an RRC (e.g., SDT paging) message. In some cases, the TA command is included in a random access response (RAR) message from the network. For example, the TA command is included in the MSGB of a two-step Random Access Channel (RACH) SDT or in the MSG2 of a four-step RACH SDT. In some embodiments, the TA command is multiplexed with downlink (DL) data. In some embodiments, the reception of the TA command in the RRC_INACTIVE state is achieved by sending a connection SDT indication for requesting time alignment and receiving the TA command in response to the connection SDT indication. In some embodiments, the first TA command or the second TA command is an SDT TA command specific to the SDT performed in the RRC_INACTIVE state. In some cases, the TAT is the SDT TAT specific to the SDT performed in the RRC_INACTIVE state. In some embodiments, the TAT is associated with one or more Timing Advance Groups (TAGs). More specifically, if the time advance command in the RRC_INACTIVE state should be updated, an SDT time advance command MAC CE can be generated via an RRC (e.g., SDT paging) message and multiplexed with the MAC SDU in the MAC PDU. The UE can then apply this time advance command when performing SDT in the RRC_INACTIVE state. Upon receiving the SDT time advance command MAC CE, an SDT timing alignment timer or a traditional timing alignment timer can be started or restarted to maintain UL time alignment when performing SDT in the RRC_INACTIVE state. The SDT time advance command MAC CE can be identified by a MAC subheader with the new LCID, such as... Figure 4A and 4B As shown, or reuse the LCID of the traditional time advance command MAC CE. (See reference) Figure 4AThis paper proposes a new SDT timing advance command, MAC CE. If SDT is performed in the RRC_INACTIVE state and only the PCell / pTAG (Primary Timing Advance Group) can be maintained, then... Figure 4A This is a command issued by the network to the UE for adjusting UL time alignment in RRC_INACTIVE state. It has a fixed size and consists of an 8-bit byte, defined as follows: R: Reserved bit for byte alignment when necessary.

[0033] SDT Time Advance Command: This field indicates the index value used to control the amount of time adjustment that the UE needs to apply when performing SDT in RRC_INACTIVE state. on the other hand, Figure 4B A new SDT time advance command MAC CE is provided for carrier aggregation (CA) scenarios, supporting more than one TAG when performing SDT in RRC_INACTIVE state. Figure 4B This is a command sent by the network to the UE to adjust UL time alignment in the RRC_INACTIVE state. It has a fixed size and consists of an 8-bit byte, defined as follows: TAG ID (Identifier): This field indicates the TAG ID associated with the TAG when performing SDT in RRC_INACTIVE state. SDT Time Advance Command: This field indicates the index value used to control the amount of time adjustment that the UE needs to apply when performing SDT in RRC_INACTIVE state. In addition to the SDT time advance command in the random access response message of RACH-based SDT in the RRC_INACTIVE state, the SDT time advance command MAC CE can also be transmitted with the MAC header of the RRC message (e.g., RRCRelease) in the RRC_CONNECTED state, and / or with the MAC header of the RRC message (e.g., RRCRelease, SDT Paging) in the RRC_INACTIVE state. In some embodiments, the method may include sending a Connection SDT indication to the network to indicate whether a Connection SDT is awaiting transmission to the network. In some embodiments, the method may include sending a Connection SDT indication to the network to indicate the amount of data to be transmitted to the network. In some embodiments, the method may include sending a Connection SDT indication to the network to indicate the termination of an SDT. In some embodiments, the method may include sending a Connection SDT indication to the network to indicate the desired SDT type for the Connection SDT. In some embodiments, the method may include sending a Connection SDT indication to the network to request a restart of the TAT in the RRC_INACTIVE state.

[0034] More specifically, the connection SDT indication is sent to indicate that at least some SDTs are waiting to be sent to the network and / or after the transmit buffer status report. In some cases, since the configured UL authorized resources are controlled by the network, it is not necessary to transmit the buffer status report in the RRC_INACTIVE state. The network only needs to determine whether resources have been allocated for the connection SDT. The connection SDT indication may be included in control information (e.g., such as...) Figures 5A to 5E The SDT indication may be at least one bit in the MAC CE of the RACH SDT, a set of periodic / aperiodic PUCCH resources on the initial / default BWP or across different BWPs, a tail bit in the data payload, or carried over with the SDT. In some cases, the SDT indication may be included in the MSGA of a two-step RACH SDT or in the MSG3 of a four-step RACH SDT. Here, the continuation SDT MAC CE is identified by a MAC subheader with a new LCID and is designed to be at least one of the following. The size of the continuation SDT MAC CE is fixed and consists of one or more continuation SDT indication fields, defined as follows. For example... Figure 5A As shown, the UE can indicate its desired SDT in the RRC_INACTIVE state. After sending the SDTMAC CE for this connection, the UE should monitor the SDT-RNTI search space to receive the connection's UL and DL schedules from the network. The format design is as follows: SDT-RNTI: The SDT-RNTI field indicates a unique identifier used to identify a specific UE when performing SDT in the RRC_INACTIVE state. In some cases, if necessary, the SDT-RNTI can be either C-RNTI or I-RNTI. SDT Continuation Indication: The SDT Continuation Indication field indicates whether the continuing SDT is awaiting transmission to the network. If the UL authorized size for each SDT is fixed and configured by the network, this field indicates how much data needs to be transmitted, allowing the network to determine multiple allocated / activated SDT resources for the UE. Furthermore, if the SDT resource is dedicated to the UE, this field indicates the termination of the SDT, allowing the network to deactivate the SDT resource allocated to the UE. On the other hand, if the total amount of data to be transmitted is not indicated in this field, it indicates which SDT type the continuing SDT wants to use (e.g., RACH-based, periodic CG-based, single CG-based), allowing the network to determine the potential size / traffic type of the continuing SDT. exist Figure 5B and Figure 5C In this context, the UE can indicate its desire to perform a call setup SDT in the RRC_INACTIVE state based on the Logical Channel Group (LCG) method, so that the network can determine the priority of the call setup SDT through Logical Channel Prioritization (LCP). Figure 5B Designed to report the SDT indication for a specific LCG, while Figure 5C This is designed as a follow-up SDT instruction for the LCG associated with the report. The format is designed as follows: R: Reserved bit for byte alignment when necessary.

[0035] LCG ID: The Logical Channel Group ID field identifies the logical channel group whose SDT is waiting to be transmitted. LCGi: The LCGi field indicates that logical channel group i has a continuing SDT indication. SDT Continuation Indication: The SDT Continuation Indication field indicates whether the continuing SDT is awaiting transmission to the network. If the UL authorized size for each SDT is fixed and configured by the network, this field indicates how much data needs to be transmitted so that the network can determine multiple allocated / activated SDT resources to provide to the UE. Furthermore, if the SDT resource is dedicated to the UE, this field indicates the termination of the SDT so that the network can deactivate the SDT resource allocated to the UE. On the other hand, if the total amount of data to be transmitted is not indicated in this field, it indicates which SDT type the continuing SDT wants to use (e.g., RACH-based, periodic CG-based, single CG-based) so that the network can determine the potential size of the continuing SDT. SDTi: The SDTi field indicates that there is an associated SDT indication for LCGi. The definition of this SDT indication is as described above. exist Figure 5D and Figure 5E In the RRC_INACTIVE state, the UE can indicate the desired SDT (Scheduled Timing Advance) based on the Timing Advance Group (TAG). Generally, if the SDT in the RRC_INACTIVE state only supports transmission on the Primary Timing Advance Group (pTAG), the UE only needs to maintain UL time alignment on the pTAG. The SDT timing alignment timer for the pTAG should then be maintained by both the network and the UE. When the UE sends the SDT MAC CE for the proposed SDT, it can instruct the network to update the timing advance command for the proposed SDT. The network can either reply to the UE's SDT timing advance command MAC CE or activate the proposed CG-based SDT resources. On the other hand, if SDT performed in RRC_INACTIVE state supports CA replication, the timing alignment timer for the Secondary Timing Advance Group (sTAG) should be maintained by the network and the UE. This format can support more than one TAG that should be maintained. Figure 5D Designed to report follow-up SDT indications for specific TAGs, while Figure 5E The SDT instruction designed as a follow-up to the TAG associated with the report. The format is designed as follows: TAG Identifier (TAGID): The Time Advance Group ID field identifies the TAG, whose successor SDT is waiting to be sent.

[0036] TAGj: The TAGj field indicates that there is a follow-up SDT indication in time advance group j. SDT Continuation Indication: The SDT Continuation Indication field indicates whether the continuing SDT is awaiting transmission to the network. If the UL authorized size for each SDT is fixed and configured by the network, this field indicates how much data needs to be transmitted, allowing the network to determine multiple allocated / activated SDT resources for the UE. Furthermore, if the SDT resource is dedicated to the UE, this field indicates the termination of the SDT, allowing the network to deactivate the SDT resource allocated to the UE. On the other hand, if the total amount of data to be transmitted is not indicated in this field, it indicates which SDT type the continuing SDT wants to use (e.g., RACH-based, periodic CG-based, single CG-based), allowing the network to determine the potential size / traffic type of the continuing SDT. SDTi: The SDTi field indicates that there is an associated SDT indication for TAGi. The definition of this SDT indication is as described above. Figure 6 A flowchart showing a method for transmitting a small amount of data in the RRC_INACTIVE state according to a first embodiment of this application. Figure 6 For networks supporting SDT in the RRC_INACTIVE state, the public / UE-specific SDT configurations are sent in the system information submitted above. For SDT UL authorization shared within the UE, the network can broadcast / unicast public / UE-specific SDT configurations (e.g., supported SDT types, SDT priorities, public / UE-specific SDT search spaces, public SDT thresholds, public SDT_RSRP thresholds, SDT paging configurations and search spaces, RACH-based SDT configurations, SDT PRACH configurations, etc.) through system information (e.g., SIB2, on-demand SI). Some UE-specific SDT configurations are sent in the RRC signaling mentioned above. For dedicated SDTs within a UE, the network can unicast UE-specific SDT configurations (e.g., supported SDT types, SDT priorities, UE-specific SDT thresholds, UE-specific SDT_RSRP thresholds, CG-based SDT configurations, SDT DL allocation configurations, SDT ran-Paging Cycles, I-RNTIs, SDT release reasons, etc.) via RRC signaling (e.g., RRC Release). Figure 6 During this process, the RRCRelease, including suspendConfig and UE-specific SDT configuration, is sent by the network to suspend or suspend the RRC connection. The UE should apply the received suspendConfig and UE-specific SDT configuration. The MAC entity is reset, therefore the timing alignment timer associated with the TAG stops or expires. Figure 4A and4B The SDT timing advance command MAC CE shown can be transmitted along with the MAC header of RRC Release. The UE can then apply the SDT timing advance command upon receiving RRC Release. An SDT timing alignment timer can be started or restarted to maintain UL timing alignment during SDT in RRC_INACTIVE state. In some cases, the legacy timing alignment timer associated with the TAG is restarted upon receiving the SDT timing advance command MAC CE. After entering RRC_INACTIVE state and UL data arriving at the UE TX buffer, the initial CG-based UL SDT is sent to the network while the SDT timing alignment timer is running. In this embodiment, the one-shot CG-based SDT type is indicated in the connection SDT transmitted / multiplexed along with the initial CG-based UL SDT. This connection SDT indication can be included in control information (e.g., such as...). Figures 5A to 5E At least one bit in the SDT MAC CE given in the code, a set of periodic / aperiodic PUCCH resources on the initial / default BWP or across different BWPs, a tail bit in the data payload, or carried over with the SDT. If necessary (shown as a dashed line), the network can determine whether to deactivate the SDT resources allocated to the UE by using SDT paging and maintain an SDT timing alignment timer for the UE, such as... Figure 4A and 4B As shown. This SDT timing alignment timer can be restarted upon receiving an SDT time advance command. When new data arrives at the UETX buffer, the CG-based SDT can operate in the RRC_INACTIVE state while maintaining UL synchronization / timing alignment.

[0037] Figure 7 A flowchart showing a method for transmitting a small amount of data in the RRC_INACTIVE state according to a second embodiment of this application. Figure 7For networks supporting SDT in the RRC_INACTIVE state, the public / UE-specific SDT configurations are sent in the system information submitted above. For SDT UL authorization shared within the UE, the network can broadcast / unicast public / UE-specific SDT configurations (e.g., supported SDT types, SDT priorities, public / UE-specific SDT search spaces, public SDT thresholds, public SDT_RSRP thresholds, SDT paging configurations and search spaces, RACH-based SDT configurations, SDT PRACH configurations, etc.) through system information (e.g., SIB2, on-demand SI). Some UE-specific SDT configurations are sent in the RRC signaling mentioned above. For dedicated SDTs within a UE, the network can unicast UE-specific SDT configurations (e.g., supported SDT types, SDT priorities, UE-specific SDT thresholds, UE-specific SDT_RSRP thresholds, CG-based SDT configurations, SDT DL allocation configurations, SDT ran-Paging Cycles, I-RNTIs, SDT release reasons, etc.) via RRC signaling (e.g., RRC Release). Figure 7 During this process, the RRCRelease, including suspendConfig and UE-specific SDT configuration, is sent by the network to suspend or suspend the RRC connection. The UE should apply the received suspendConfig and UE-specific SDT configuration. The MAC entity is reset, therefore the timing alignment timer associated with the TAG stops or expires. Figure 4A and 4B The SDT timing advance command MAC CE shown can be transmitted along with the MAC header of RRC Release. The UE can then apply the SDT timing advance command upon receiving RRC Release. An SDT timing alignment timer can be started or restarted to maintain UL timing alignment during SDT in RRC_INACTIVE state. In some cases, the legacy timing alignment timer associated with the TAG is restarted upon receiving the SDT timing advance command MAC CE. After entering RRC_INACTIVE state and UL data arriving at the UE TX buffer, the initial CG-based UL SDT is sent to the network while the SDT timing alignment timer is running. In this embodiment, the one-shot CG-based SDT type is indicated in the connection SDT transmitted / multiplexed along with the initial CG-based UL SDT. This connection SDT indication can be included in control information (e.g., such as...). Figures 5A to 5EAt least one bit from the SDT MAC CE given in the code, a set of periodic / aperiodic PUCCH resources on the initial / default BWP or across different BWPs, tail bits in the data payload, or carried over with the SDT. If necessary ( Figure 7 (Not shown in the text) The network can determine whether to deactivate the SDT resources allocated to the UE by using SDT paging, and maintain an SDT timing alignment timer for the UE, such as... Figure 4A and 4B As shown. After a period of time, if the UE does not receive any SDT time advance command MAC CE from the network for some reason (e.g., missed SDT paging), and new data arrives at the UE TX buffer, the UE can initiate a two-step or four-step RACH-based SDT according to the SDT threshold. If the UE decides to initiate a two-step RACH-based SDT, a small amount of data from the UL and optional DL is transmitted on the MSGA and MSGB, respectively. Furthermore, the MSGA may include an RCResumeRequest multiplexed with the SDT continuation indication, while the MSGB includes an RCRelease multiplexed with the SDT time advance command MAC CE. The SDT timing alignment timer starts or restarts upon receiving the SDT time advance command included in the MSGB. If the UE decides to initiate a four-step RACH-based SDT ( Figure 7 (Not shown in the text), then small amounts of UL and DL data are transmitted on MSG3 and MSG4 respectively. Furthermore, MSG3 may include an RRCresumeRequest multiplexed with the SDT continuation indication, while MSG4 may include an RRCRelease multiplexed with DL data if necessary. The SDT timing alignment timer is restarted upon receiving an SDT time advance command included in MSG2. In this embodiment, besides SDT paging in the RRC_INACTIVE state, the SDT timing alignment timer can also be maintained by MSGB or MSG2. Figure 8 A flowchart showing a method for transmitting a small amount of data in the RRC_INACTIVE state according to a third embodiment of this application is displayed. Figure 8For networks supporting SDT in the RRC_INACTIVE state, the public / UE-specific SDT configurations are sent in the system information submitted above. For SDT UL authorization shared within the UE, the network can broadcast / unicast public / UE-specific SDT configurations (e.g., supported SDT types, SDT priorities, public / UE-specific SDT search spaces, public SDT thresholds, public SDT_RSRP thresholds, SDT paging configurations and search spaces, RACH-based SDT configurations, SDT PRACH configurations, etc.) through system information (e.g., SIB2, on-demand SI). Some UE-specific SDT configurations are sent in the RRC signaling mentioned above. For dedicated SDTs within a UE, the network can unicast UE-specific SDT configurations (e.g., supported SDT types, SDT priorities, UE-specific SDT thresholds, UE-specific SDT_RSRP thresholds, CG-based SDT configurations, SDT DL allocation configurations, SDT ran-Paging Cycles, I-RNTIs, SDT release reasons, etc.) via RRC signaling (e.g., RRC Release). Figure 8 During this process, the RRCRelease, including suspendConfig and UE-specific SDT configuration, is sent by the network to suspend or suspend the RRC connection. The UE should apply the received suspendConfig and UE-specific SDT configuration. The MAC entity is reset, therefore the timing alignment timer associated with the TAG stops or expires. Figure 4A and 4BThe SDT timing advance command MAC CE shown can be transmitted along with the MAC header of the RRRCRelease. The UE can then apply the SDT timing advance command upon receiving the RRRCRelease. The SDT timing alignment timer can be started or restarted to maintain UL timing alignment during SDT in the RRC_INACTIVE state. In some cases, the legacy timing alignment timer associated with the TAG restarts upon receiving the SDT timing advance command MAC CE. After entering the RRC_INACTIVE state and initial UL data arriving at the UE TX buffer, the UE can initiate a two-step or four-step RACH-based SDT based on the SDT threshold, regardless of whether the SDT timing alignment timer is running. If the UE decides to initiate a two-step RACH-based SDT, small amounts of UL and optional DL data are transmitted on the MSGA and MSGB, respectively. Furthermore, the MSGA may include an RRRCResumeRequest multiplexed with the SDT continuation indication, while the MSGB includes an RRRCRelease multiplexed with the SDT timing advance command MAC CE. The SDT timing alignment timer starts or restarts upon receiving the SDT timing advance command included in the MSGB. If the UE decides to initiate a four-step RACH-based SDT ( Figure 8 (Not shown in the image), then small amounts of UL and DL data are transmitted on MSG3 and MSG4 respectively. Furthermore, MSG3 may include an RRCresumeRequest multiplexed with the SDT continuation indication, while MSG4 may include an RRCrease multiplexed with DL data if necessary. The SDT timing alignment timer is restarted upon receiving an SDT time advance command included in MSG2. Afterwards, if new data arrives at the UE TX buffer, the UE determines whether to perform CG-based SDT (SDT based on the SDT threshold) while the SDT timing alignment timer is running. Figure 8 (Not shown in the text), or perform two-step or four-step RACH-based SDT. Figure 9 A flowchart showing a method for transmitting small amounts of data in the RRC_INACTIVE state according to a fourth embodiment of this application. Figure 9For networks supporting SDT in the RRC_INACTIVE state, the public / UE-specific SDT configurations are sent in the system information submitted above. For SDT UL authorization shared within the UE, the network can broadcast / unicast public / UE-specific SDT configurations (e.g., supported SDT types, SDT priorities, public / UE-specific SDT search spaces, public SDT thresholds, public SDT_RSRP thresholds, SDT paging configurations and search spaces, RACH-based SDT configurations, SDT PRACH configurations, etc.) through system information (e.g., SIB2, on-demand SI). Some UE-specific SDT configurations are sent in the RRC signaling mentioned above. For dedicated SDTs within a UE, the network can unicast UE-specific SDT configurations (e.g., supported SDT types, SDT priorities, UE-specific SDT thresholds, UE-specific SDT_RSRP thresholds, CG-based SDT configurations, SDT DL allocation configurations, SDT ran-Paging Cycles, I-RNTIs, SDT release reasons, etc.) via RRC signaling (e.g., RRC Release). Figure 9 During this process, the RRCRelease, including suspendConfig and UE-specific SDT configuration, is sent by the network to suspend or suspend the RRC connection. The UE should apply the received suspendConfig and UE-specific SDT configuration. The MAC entity is reset, therefore the timing alignment timer associated with the TAG stops or expires. Figure 4A and 4BThe SDT timing advance command MAC CE shown can be transmitted along with the MAC header of the RRRCRelease. The UE can then apply the SDT timing advance command upon receiving the RRRCRelease. The SDT timing alignment timer can be started or restarted to maintain UL timing alignment during SDT in the RRC_INACTIVE state. In some cases, the legacy timing alignment timer associated with the TAG restarts upon receiving the SDT timing advance command MAC CE. After entering the RRC_INACTIVE state and initial UL data arriving at the UE TX buffer, the UE can initiate a two-step or four-step RACH-based SDT based on the SDT threshold, regardless of whether the SDT timing alignment timer is running. If the UE decides to initiate a two-step RACH-based SDT, small amounts of UL and optional DL data are transmitted on the MSGA and MSGB, respectively. Furthermore, the MSGA may include an RRRCResumeRequest multiplexed with the SDT continuation indication, while the MSGB includes an RRRCRelease multiplexed with the SDT timing advance command MAC CE. The SDT timing alignment timer starts or restarts upon receiving the SDT timing advance command included in the MSGB. If the UE decides to initiate a four-step RACH-based SDT ( Figure 9 (Not shown in the image), then small amounts of UL and DL data are transmitted on MSG3 and MSG4 respectively. Furthermore, MSG3 may include an RRCresumeRequest multiplexed with the SDT continuation indication, while MSG4 may include an RRCrease multiplexed with DL data if necessary. This SDT timing alignment timer is restarted upon receiving an SDT time advance command included in MSG2. If necessary (shown as a dashed line), the network can maintain this SDT timing alignment timer for the UE by using SDT paging, such as... Figure 4A and 4B As shown. This SDT timing alignment timer can be restarted upon receiving an SDT time advance command. When new data arrives at the UE's TX buffer, while the SDT timing alignment timer is running, the UE determines whether to perform CG-based SDT, or a two-step or four-step RACH-based SDT, based on the SDT threshold. Figure 9 (Not shown in the text). In some cases, when there is incoming or new data arriving at the UE TX buffer, CG-based SDT can operate in the RRC_INACTIVE state while maintaining UL synchronization / time alignment.

[0038] Figure 10 A flowchart showing a method for transmitting a small amount of data in the RRC_INACTIVE state according to a fifth embodiment of this application. Figure 10For networks supporting SDT in the RRC_INACTIVE state, the public / UE-specific SDT configurations are sent in the system information submitted above. For SDT UL authorization shared within the UE, the network can broadcast / unicast public / UE-specific SDT configurations (e.g., supported SDT types, SDT priorities, public / UE-specific SDT search spaces, public SDT thresholds, public SDT_RSRP thresholds, SDT paging configurations and search spaces, RACH-based SDT configurations, SDT PRACH configurations, etc.) through system information (e.g., SIB2, on-demand SI). Some UE-specific SDT configurations are sent in the RRC signaling mentioned above. For dedicated SDTs within a UE, the network can unicast UE-specific SDT configurations (e.g., supported SDT types, SDT priorities, UE-specific SDT thresholds, UE-specific SDT_RSRP thresholds, CG-based SDT configurations, SDT DL allocation configurations, SDT ran-Paging Cycles, I-RNTIs, SDT release reasons, etc.) via RRC signaling (e.g., RRC Release). Figure 10 During this process, the RRCRelease, including suspendConfig and UE-specific SDT configuration, is sent by the network to suspend or suspend the RRC connection. The UE should apply the received suspendConfig and UE-specific SDT configuration. The MAC entity is reset, therefore the timing alignment timer associated with the TAG stops or expires. After entering the RRC_INACTIVE state, as... Figure 4A and 4B The SDT time advance command MAC CE shown can be transmitted along with the MAC header of the SDT paging. The UE can then apply the SDT time advance command upon receiving an SDT paging. An SDT timing alignment timer can be started to maintain UL time alignment during SDT in RRC_INACTIVE state. When UL data arrives at the UE TX buffer, the initial CG-based UL SDT is sent to the network while the SDT timing alignment timer is running. In other words, the CG-based SDT can only be started while the SDT timing alignment timer is running. This connection SDT indication can be sent / multiplexed along with the initial CG-based UL SDT. This connection SDT indication can be included in control information (e.g., such as...). Figures 5A to 5EAt least one bit in the SDT MAC CE given in the code, a set of periodic / aperiodic PUCCH resources on the initial / default BWP or across different BWPs, a tail bit in the data payload, or carried over with the SDT. If necessary (shown as a dashed line), the network can determine whether to deactivate the SDT resources allocated to the UE by using SDT paging and maintain an SDT timing alignment timer for the UE, such as... Figure 4A and 4B As shown. This SDT timing alignment timer can be restarted upon receiving an SDT time advance command. When incoming or new data arrives at the UE TX buffer, the CG-based SDT can operate in the RRC_INACTIVE state while maintaining UL synchronization / timing alignment.

[0039] Figure 11 A flowchart showing a method for transmitting small amounts of data in the RRC_INACTIVE state according to a sixth embodiment of this application. Figure 11 For networks supporting SDT in the RRC_INACTIVE state, the public / UE-specific SDT configurations are sent in the system information submitted above. For SDT UL authorization shared within the UE, the network can broadcast / unicast public / UE-specific SDT configurations (e.g., supported SDT types, SDT priorities, public / UE-specific SDT search spaces, public SDT thresholds, public SDT_RSRP thresholds, SDT paging configurations and search spaces, RACH-based SDT configurations, SDT PRACH configurations, etc.) through system information (e.g., SIB2, on-demand SI). Some UE-specific SDT configurations are sent in the RRC signaling mentioned above. For dedicated SDTs within a UE, the network can unicast UE-specific SDT configurations (e.g., supported SDT types, SDT priorities, UE-specific SDT thresholds, UE-specific SDT_RSRP thresholds, CG-based SDT configurations, SDT DL allocation configurations, SDT ran-Paging Cycles, I-RNTIs, SDT release reasons, etc.) via RRC signaling (e.g., RRC Release). Figure 11In the process, the RRCResumeRequest, which includes suspendConfig and UE-specific SDT configuration, is sent by the network to suspend or suspend the RRC connection. The UE should apply the received suspendConfig and UE-specific SDT configuration. The MAC entity is reset, so the timing alignment timer associated with the TAG stops or expires. After entering the RRC_INACTIVE state and the UL data arrives at the UE TX buffer, the UE can initiate a two-step or four-step RACH-based SDT to trigger the SDT timing alignment timer based on the SDT threshold. If the UE decides to initiate a two-step RACH-based SDT, a small amount of UL and optional DL data is transmitted on the MSGA and MSGB, respectively. In addition, the MSGA may include an RRCResumeRequest multiplexed with the SDT continuation indication, while the MSGB includes an RRCResumeRequest multiplexed with the SDT timing advance command MAC CE. The SDT timing alignment timer starts when the SDT timing advance command included in the MSGB is received. If the UE decides to initiate a four-step RACH-based SDT ( Figure 11 (Not shown in the image), then small amounts of UL and DL data are transmitted on MSG3 and MSG4 respectively. Furthermore, MSG3 may include an RRCresumeRequest multiplexed with the continuation SDT indication, while MSG4 may include an RRCrease multiplexed with DL data if necessary. The SDT timing alignment timer starts upon receiving an SDT time advance command included in MSG2. Subsequently, if continuation data or new data arrives at the UE TX buffer, the UE, while the SDT timing alignment timer is running, determines whether to perform CG-based SDT, or a two-step or four-step RACH-based SDT, based on the SDT threshold. In some cases, when new data arrives at the UE TX buffer, CG-based SDT (… Figure 11 (Not shown in the text) can run in RRC_INACTIVE state while maintaining UL synchronization / time alignment.

[0040] Figure 12 A flowchart showing a method for transmitting small amounts of data in the RRC_INACTIVE state according to the seventh embodiment of this application. Figure 12For networks supporting SDT in the RRC_INACTIVE state, the public / UE-specific SDT configurations are sent in the system information submitted above. For SDT UL authorization shared within the UE, the network can broadcast / unicast public / UE-specific SDT configurations (e.g., supported SDT types, SDT priorities, public / UE-specific SDT search spaces, public SDT thresholds, public SDT_RSRP thresholds, SDT paging configurations and search spaces, RACH-based SDT configurations, SDT PRACH configurations, etc.) through system information (e.g., SIB2, on-demand SI). Some UE-specific SDT configurations are sent in the RRC signaling mentioned above. For dedicated SDTs within a UE, the network can unicast UE-specific SDT configurations (e.g., supported SDT types, SDT priorities, UE-specific SDT thresholds, UE-specific SDT_RSRP thresholds, CG-based SDT configurations, SDT DL allocation configurations, SDT ran-Paging Cycles, I-RNTIs, SDT release reasons, etc.) via RRC signaling (e.g., RRC Release). Figure 12 In the process, the RRCResumeRequest, which includes suspendConfig and UE-specific SDT configuration, is sent by the network to suspend or suspend the RRC connection. The UE should apply the received suspendConfig and UE-specific SDT configuration. The MAC entity is reset, so the timing alignment timer associated with the TAG stops or expires. After entering the RRC_INACTIVE state and the UL data arrives at the UE TX buffer, the UE can initiate a two-step or four-step RACH-based SDT to trigger the SDT timing alignment timer based on the SDT threshold. If the UE decides to initiate a two-step RACH-based SDT, a small amount of UL and optional DL data is transmitted on the MSGA and MSGB, respectively. In addition, the MSGA may include an RRCResumeRequest multiplexed with the SDT continuation indication, while the MSGB includes an RRCResumeRequest multiplexed with the SDT timing advance command MAC CE. The SDT timing alignment timer starts when the SDT timing advance command included in the MSGB is received. If the UE decides to initiate a four-step RACH-based SDT ( Figure 12(Not shown in the image), then small amounts of UL and DL data are transmitted on MSG3 and MSG4 respectively. Furthermore, MSG3 may include an RRCresumeRequest multiplexed with the SDT continuation indication, while MSG4 may include an RRCrease multiplexed with DL data if necessary. This SDT timing alignment timer starts upon receiving an SDT time advance command included in MSG2. If necessary (shown as a dashed line), the network can maintain this SDT timing alignment timer for the UE by using SDT paging, such as... Figure 4A and 4B As shown. This SDT timing alignment timer can be restarted upon receiving an SDT time advance command. When new data arrives at the UE's TX buffer, while the SDT timing alignment timer is running, the UE determines whether to perform CG-based SDT, or a two-step or four-step RACH-based SDT, based on the SDT threshold. Figure 12 (Not shown in the text). In some cases, when there is incoming or new data arriving at the UE TX buffer, CG-based SDT can operate in the RRC_INACTIVE state while maintaining UL synchronization / time alignment.

[0041] Figure 13 A flowchart showing a method for transmitting a small amount of data in the RRC_INACTIVE state according to the eighth embodiment of this application is displayed. Figure 13 For networks supporting SDT in the RRC_INACTIVE state, the public / UE-specific SDT configurations are sent in the system information submitted above. For SDT UL authorization shared within the UE, the network can broadcast / unicast public / UE-specific SDT configurations (e.g., supported SDT types, SDT priorities, public / UE-specific SDT search spaces, public SDT thresholds, public SDT_RSRP thresholds, SDT paging configurations and search spaces, RACH-based SDT configurations, SDT PRACH configurations, etc.) through system information (e.g., SIB2, on-demand SI). Some UE-specific SDT configurations are sent in the RRC signaling mentioned above. For dedicated SDTs within a UE, the network can unicast UE-specific SDT configurations (e.g., supported SDT types, SDT priorities, UE-specific SDT thresholds, UE-specific SDT_RSRP thresholds, CG-based SDT configurations, SDT DL allocation configurations, SDT ran-Paging Cycles, I-RNTIs, SDT release reasons, etc.) via RRC signaling (e.g., RRC Release). Figure 13During this process, the RRCRelease, including suspendConfig and UE-specific SDT configuration, is sent by the network to suspend or suspend the RRC connection. The UE should apply the received suspendConfig and UE-specific SDT configuration. The MAC entity is reset, therefore the timing alignment timer associated with the TAG stops or expires. Figure 4A and 4B The SDT timing advance command MAC CE shown can be transmitted along with the MAC header of the RRC Release. The UE can then apply the SDT timing advance command upon receiving the RRC Release. The SDT timing alignment timer can be started or restarted to maintain UL timing alignment during SDT in the RRC_INACTIVE state. In some cases, the legacy timing alignment timer associated with the TAG is restarted upon receiving the SDT timing advance command MAC CE. After entering the RRC_INACTIVE state and UL data arriving at the UE TX buffer, the initial CG-based UL SDT is sent to the network while the SDT timing alignment timer is running. If necessary, DL data is transmitted on pre-configured DL allocation resources or multiplexed with the SDT paging message. For the successive UL SDT, a buffer status report or successive SDT indication should be sent / multiplexed along with the initial CG-based UL SDT. This successive SDT indication can be included in control information (e.g., such as...). Figures 5A to 5E At least one bit in the SDT MAC CE given in the code, a set of periodic / aperiodic PUCCH resources on the initial / default BWP or across different BWPs, tail bits in the data payload, or carried over with the SDT. If necessary (shown as dashed lines), such as... Figure 4A and 4B The SDT timing advance command MAC CE shown can be replied to via the MAC header of the DL data and / or multiplexed with SDT paging. Upon receiving the SDT timing advance command MAC CE, the UE should apply the SDT timing advance command to the indicated TAG and, if necessary, restart the SDT timing alignment timer for the associated TAG. In some cases, the connection SDT indication can indicate that there are other connection SDTs waiting to be sent to the network, and then the CG-based SDT can easily continue to operate while maintaining UL timing alignment. In other cases, if the connection SDT indication indicates that no further SDTs are to be sent within a certain period, the network can determine whether to deactivate the SDT resources allocated to the UE and maintain the SDT timing alignment timer for the UE by using SDT paging, such as... Figure 4A and 4BAs shown. If the network decides to maintain CG-based resource allocation, CG-based SDT can be transmitted in a low-latency and low-power manner in the RRC_INACTIVE state. If the network decides to deactivate CG-based resource allocation, it can be activated when a follow-up SDT indication is received, for example, via PUCCH (not shown). For a period thereafter, the UE can still perform CG-based SDT while the SDT timing alignment timer is running. When maintaining UL synchronization / timing alignment in the RRC_INACTIVE state, both CG-based SDT and follow-up CG-based SDT can operate in the RRC_INACTIVE state. Figure 14 A flowchart showing a method for transmitting small amounts of data in the RRC_INACTIVE state according to the ninth embodiment of this application is displayed. Figure 14 For networks supporting SDT in the RRC_INACTIVE state, the public / UE-specific SDT configurations are sent in the system information submitted above. For SDT UL authorization shared within the UE, the network can broadcast / unicast public / UE-specific SDT configurations (e.g., supported SDT types, SDT priorities, public / UE-specific SDT search spaces, public SDT thresholds, public SDT_RSRP thresholds, SDT paging configurations and search spaces, RACH-based SDT configurations, SDT PRACH configurations, etc.) through system information (e.g., SIB2, on-demand SI). Some UE-specific SDT configurations are sent in the RRC signaling mentioned above. For dedicated SDTs within a UE, the network can unicast UE-specific SDT configurations (e.g., supported SDT types, SDT priorities, UE-specific SDT thresholds, UE-specific SDT_RSRP thresholds, CG-based SDT configurations, SDT DL allocation configurations, SDT ran-Paging Cycles, I-RNTIs, SDT release reasons, etc.) via RRC signaling (e.g., RRC Release). Figure 14 During this process, the RRCRelease, including suspendConfig and UE-specific SDT configuration, is sent by the network to suspend or suspend the RRC connection. The UE should apply the received suspendConfig and UE-specific SDT configuration. The MAC entity is reset, therefore the timing alignment timer associated with the TAG stops or expires. Figure 4A and 4BThe SDT timing advance command MAC CE shown can be transmitted along with the MAC header of the RRC Release. The UE can then apply the SDT timing advance command upon receiving the RRC Release. The SDT timing alignment timer can be started or restarted to maintain UL timing alignment during SDT in the RRC_INACTIVE state. In some cases, the legacy timing alignment timer associated with the TAG is restarted upon receiving the SDT timing advance command MAC CE. After entering the RRC_INACTIVE state and UL data arriving at the UE TX buffer, the initial CG-based UL SDT is sent to the network while the SDT timing alignment timer is running. If necessary, DL data is transmitted on DL allocation resources or multiplexed with the SDT paging message. For the successive UL SDT, a buffer status report or successive SDT indication should be sent / multiplexed along with the initial CG-based UL SDT. This successive SDT indication can be included in control information (e.g., such as...). Figures 5A to 5E At least one bit in the following sequence (SDT MAC CE), a set of periodic / aperiodic PUCCH resources on the initial / default BWP or across different BWPs, tail bits in the data payload, or carried over with the SDT. Figure 4A and 4B The SDT timing advance command MAC CE shown can be replied to via the MAC header of the SDT paging, and / or transmitted with DL data if necessary. Upon receiving the SDT timing advance command MAC CE, the UE should apply the SDT timing advance command for the indicated TAG and restart the SDT timing alignment timer for the associated TAG. In some cases, if there is a continuation SDT or new data waiting to be sent to the network, but the UE may miss the transmission timing on CG resources for some reason (e.g., using an invalid TA value due to an RSRP change), the UE can initiate a two-step RACH-based SDT when the UL SDT is ready and the SDT threshold is met. Small amounts of UL and DL data are transmitted on the MSGA and MSGB, respectively. Furthermore, the MSGA may include an RRCresumeRequest multiplexed with the continuation SDT indication, while the MSGB may include an RRCrease multiplexed with the SDT timing advance command MAC CE. The SDT timing alignment timer is restarted upon receiving the SDT timing advance command included in the MSGB. CG-based resources can be reactivated after the SDT timing alignment timer is updated. In other words, even if the UE misses the transmission timing on CG resources for a period of time, it can still perform CG-based SDT after a two-step RACH-based SDT. In other cases, when the UL SDT is ready and the SDT threshold is met, the UE can initiate a four-step RACH-based SDT. Figure 14 (Not shown in the image). Small amounts of UL and DL data are transmitted on MSG3 and MSG4, respectively. Furthermore, MSG3 may include an RRCResumeRequest multiplexed with the continuation SDT indication, while MSG4 may include an RRCRelease multiplexed with DL data if necessary. The SDT timing alignment timer is restarted upon receiving an SDT time advance command included in MSG2. CG-based resources can be reactivated after the SDT timing alignment timer is updated. In other words, even if the UE misses transmission timing on CG resources for a period of time, it can still perform a CG-based SDT after a four-step RACH-based SDT. When maintaining UL synchronization / timing alignment in the RRC_INACTIVE state, both the CG-based SDT and the continuation RACH-based / CG-based SDT can run in the RRC_INACTIVE state. Figure 15 A flowchart showing a method for transmitting small amounts of data in the RRC_INACTIVE state according to the tenth embodiment of this application is displayed. Figure 15 For networks supporting SDT in the RRC_INACTIVE state, the public / UE-specific SDT configurations are sent in the system information submitted above. For SDT UL authorization shared within the UE, the network can broadcast / unicast public / UE-specific SDT configurations (e.g., supported SDT types, SDT priorities, public / UE-specific SDT search spaces, public SDT thresholds, public SDT_RSRP thresholds, SDT paging configurations and search spaces, RACH-based SDT configurations, SDT PRACH configurations, etc.) through system information (e.g., SIB2, on-demand SI). Some UE-specific SDT configurations are sent in the RRC signaling mentioned above. For dedicated SDTs within a UE, the network can unicast UE-specific SDT configurations (e.g., supported SDT types, SDT priorities, UE-specific SDT thresholds, UE-specific SDT_RSRP thresholds, CG-based SDT configurations, SDT DL allocation configurations, SDT ran-Paging Cycles, I-RNTIs, SDT release reasons, etc.) via RRC signaling (e.g., RRC Release). Figure 15 During this process, the RRCRelease, including suspendConfig and UE-specific SDT configuration, is sent by the network to suspend or suspend the RRC connection. The UE should apply the received suspendConfig and UE-specific SDT configuration. The MAC entity is reset, therefore the timing alignment timer associated with the TAG stops or expires. Figure 4A and 4BThe SDT timing advance command MAC CE shown can be transmitted along with the MAC header of the RRC Release. The UE can then apply the SDT timing advance command upon receiving the RRC Release. The SDT timing alignment timer can be started or restarted to maintain UL timing alignment during SDT in the RRC_INACTIVE state. In some cases, the legacy timing alignment timer associated with the TAG is restarted upon receiving the SDT timing advance command MAC CE. After entering the RRC_INACTIVE state and UL data arriving at the UE TX buffer, the initial CG-based UL SDT is sent to the network while the SDT timing alignment timer is running. If necessary, DL data is transmitted on DL allocation resources or multiplexed with the SDT paging message. For the successive UL SDT, a buffer status report or successive SDT indication should be sent / multiplexed along with the initial UL SDT in the CG-based SDT. This successive SDT indication can be included in control information (e.g., such as...). Figures 5A to 5E At least one bit in the following sequence (SDT MAC CE), a set of periodic / aperiodic PUCCH resources on the initial / default BWP or across different BWPs, tail bits in the data payload, or carried over with the SDT. Figure 4A and 4B The SDT timing advance command MAC CE shown can be replied to via the MAC header of the SDT paging, and / or transmitted with DL data if necessary. Upon receiving the SDT timing advance command MAC CE, the UE should apply the SDT timing advance command to the indicated TAG and restart the SDT timing alignment timer for the associated TAG. In some cases, if there is a continuation SDT or new data waiting to be sent to the network, but the UE may have missed the transmission timing on the CG resource for some reason (e.g., due to an invalid TA value being used because of an RSRP change), the UE can send a continuation SDT indication to request timing alignment. This SDT timing alignment timer can be started or restarted using SDT paging, such as... Figure 4A and 4B As shown. When maintaining UL synchronization / time alignment in the RRC_INACTIVE state, CG-based SDT and subsequent RACH-based / CG-based SDT can run in the RRC_INACTIVE state. Figure 16 A flowchart showing a method for transmitting small amounts of data in the RRC_INACTIVE state according to the eleventh embodiment of this application is displayed. Figure 16For networks supporting SDT in the RRC_INACTIVE state, the public / UE-specific SDT configurations are sent in the system information submitted above. For SDT UL authorization shared within the UE, the network can broadcast / unicast public / UE-specific SDT configurations (e.g., supported SDT types, SDT priorities, public / UE-specific SDT search spaces, public SDT thresholds, public SDT_RSRP thresholds, SDT paging configurations and search spaces, RACH-based SDT configurations, SDT PRACH configurations, etc.) through system information (e.g., SIB2, on-demand SI). Some UE-specific SDT configurations are sent in the RRC signaling mentioned above. For dedicated SDTs within a UE, the network can unicast UE-specific SDT configurations (e.g., supported SDT types, SDT priorities, UE-specific SDT thresholds, UE-specific SDT_RSRP thresholds, CG-based SDT configurations, SDT DL allocation configurations, SDT ran-Paging Cycles, I-RNTIs, SDT release reasons, etc.) via RRC signaling (e.g., RRC Release). Figure 16 During this process, the RRCRelease, including suspendConfig and UE-specific SDT configuration, is sent by the network to suspend or suspend the RRC connection. The UE should apply the received suspendConfig and UE-specific SDT configuration. The MAC entity is reset, therefore the timing alignment timer associated with the TAG stops or expires. After entering the RRC_INACTIVE state, as... Figure 4A and 4B The SDT time advance command MAC CE shown can be transmitted along with the MAC header of the SDT paging. The UE can then apply the SDT time advance command upon receiving an SDT paging. An SDT timing alignment timer can be started to maintain UL time alignment during SDT in RRC_INACTIVE state. When UL data arrives at the UE TX buffer, the initial CG-based UL SDT is sent to the network while the SDT timing alignment timer is running. In other words, the CG-based SDT can only be started while the SDT timing alignment timer is running. This connection SDT indication can be sent / multiplexed along with the initial CG-based UL SDT. This connection SDT indication can be included in control information (e.g., such as...). Figures 5A to 5EAt least one bit in the connection SDT MAC CE given in the code, a set of periodic / aperiodic PUCCH resources on the initial / default BWP or across different BWPs, tail bits in the data payload, or carried along with the SDT. In some cases, the connection SDT indication can indicate that there are other connection SDTs waiting to be sent to the network, and then the CG-based SDT can easily continue to operate while maintaining UL timing alignment. In other cases, if the connection SDT indication indicates that no further SDTs are to be sent within a certain period of time, the network can determine whether to deactivate the SDT resources allocated to the UE and maintain an SDT timing alignment timer for the UE by using SDT paging, such as... Figure 4A and 4B As shown. If the network decides to maintain CG-based resource allocation, CG-based SDT can be transmitted in a low-latency and low-power manner in the RRC_INACTIVE state. If the network decides to deactivate CG-based resource allocation, it can be activated when a follow-up SDT indication is received, for example, via PUCCH (not shown). For a period thereafter, the UE can still perform CG-based SDT while the SDT timing alignment timer is running. When maintaining UL synchronization / timing alignment in the RRC_INACTIVE state, both CG-based SDT and follow-up CG-based SDT can operate in the RRC_INACTIVE state. Figure 17 A flowchart showing a method for transmitting small amounts of data in the RRC_INACTIVE state according to the twelfth embodiment of this application is displayed. Figure 17For networks supporting SDT in the RRC_INACTIVE state, the public / UE-specific SDT configurations are sent in the system information submitted above. For SDT UL authorization shared within the UE, the network can broadcast / unicast public / UE-specific SDT configurations (e.g., supported SDT types, SDT priorities, public / UE-specific SDT search spaces, public SDT thresholds, public SDT_RSRP thresholds, SDT paging configurations and search spaces, RACH-based SDT configurations, SDT PRACH configurations, etc.) through system information (e.g., SIB2, on-demand SI). Some UE-specific SDT configurations are sent in the RRC signaling mentioned above. For dedicated SDTs within a UE, the network can unicast UE-specific SDT configurations (e.g., supported SDT types, SDT priorities, UE-specific SDT thresholds, UE-specific SDT_RSRP thresholds, CG-based SDT configurations, SDT DL allocation configurations, SDT ran-Paging Cycles, I-RNTIs, SDT release reasons, etc.) via RRC signaling (e.g., RRC Release). Figure 17 During this process, the RRCRelease, including suspendConfig and UE-specific SDT configuration, is sent by the network to suspend or suspend the RRC connection. The UE should apply the received suspendConfig and UE-specific SDT configuration. The MAC entity is reset, therefore the timing alignment timer associated with the TAG stops or expires. After entering the RRC_INACTIVE state, as... Figure 4A and 4B The SDT time advance command MAC CE shown can be transmitted along with the MAC header of the SDT paging. The UE can then apply the SDT time advance command upon receiving an SDT paging. An SDT timing alignment timer can be started to maintain UL time alignment during SDT in RRC_INACTIVE state. When UL data arrives at the UE TX buffer, the initial CG-based UL SDT is sent to the network while the SDT timing alignment timer is running. In other words, the CG-based SDT can only be started while the SDT timing alignment timer is running. This connection SDT indication can be sent / multiplexed along with the initial CG-based UL SDT. This connection SDT indication can be included in control information (e.g., such as...). Figures 5A to 5EAt least one bit in the continuation SDT MAC CE given in the diagram, a set of periodic / aperiodic PUCCH resources on the initial / default BWP or across different BWPs, tail bits in the data payload, or carried over with the SDT. In some cases, if there is a continuation SDT or new data waiting to be sent to the network, but the UE may miss the transmission timing on the CG resource for some reason (e.g., using an invalid TA value due to an RSRP change), the UE can initiate a two-step RACH-based SDT when the UL SDT is ready and the SDT threshold is met. Small amounts of UL and DL data are transmitted on the MSGA and MSGB, respectively. In addition, the MSGA may include an RCResumeRequest multiplexed with the continuation SDT indication, while the MSGB may include an RCRelease multiplexed with the SDT timing advance command MAC CE. The SDT timing alignment timer is restarted upon receiving the SDT timing advance command included in the MSGB. CG-based resources can be reactivated after the SDT timing alignment timer is updated. In other words, even if the UE misses the transmission timing on CG resources for a period of time, it can still perform CG-based SDT after a two-step RACH-based SDT. In other cases, when the UL SDT is ready and the SDT threshold is met, the UE can initiate a four-step RACH-based SDT. Figure 17 (Not shown in the image). Small amounts of UL and DL data are transmitted on MSG3 and MSG4, respectively. Furthermore, MSG3 may include an RRCResumeRequest multiplexed with the continuation SDT indication, while MSG4 may include an RRCRelease multiplexed with DL data if necessary. The SDT timing alignment timer is restarted upon receiving an SDT time advance command included in MSG2. CG-based resources can be reactivated after the SDT timing alignment timer is updated. In other words, even if the UE misses transmission timing on CG resources for a period of time, it can still perform a CG-based SDT after a four-step RACH-based SDT. When maintaining UL synchronization / timing alignment in the RRC_INACTIVE state, both the CG-based SDT and the continuation RACH-based / CG-based SDT can run in the RRC_INACTIVE state. Figure 18 A flowchart showing a method for transmitting small amounts of data in the RRC_INACTIVE state according to the thirteenth embodiment of this application is displayed. Figure 18For networks supporting SDT in the RRC_INACTIVE state, the public / UE-specific SDT configurations are sent in the system information submitted above. For SDT UL authorization shared within the UE, the network can broadcast / unicast public / UE-specific SDT configurations (e.g., supported SDT types, SDT priorities, public / UE-specific SDT search spaces, public SDT thresholds, public SDT_RSRP thresholds, SDT paging configurations and search spaces, RACH-based SDT configurations, SDT PRACH configurations, etc.) through system information (e.g., SIB2, on-demand SI). Some UE-specific SDT configurations are sent in the RRC signaling mentioned above. For dedicated SDTs within a UE, the network can unicast UE-specific SDT configurations (e.g., supported SDT types, SDT priorities, UE-specific SDT thresholds, UE-specific SDT_RSRP thresholds, CG-based SDT configurations, SDT DL allocation configurations, SDT ran-Paging Cycles, I-RNTIs, SDT release reasons, etc.) via RRC signaling (e.g., RRC Release). Figure 18 During this process, the RRCRelease, including suspendConfig and UE-specific SDT configuration, is sent by the network to suspend or suspend the RRC connection. The UE should apply the received suspendConfig and UE-specific SDT configuration. The MAC entity is reset, therefore the timing alignment timer associated with the TAG stops or expires. After entering the RRC_INACTIVE state, as... Figure 4A and 4B The SDT time advance command MAC CE shown can be transmitted along with the MAC header of the SDT paging. The UE can then apply the SDT time advance command upon receiving an SDT paging. An SDT timing alignment timer can be started to maintain UL time alignment during SDT in RRC_INACTIVE state. When UL data arrives at the UE TX buffer, the initial CG-based UL SDT is sent to the network while the SDT timing alignment timer is running. In other words, the CG-based SDT can only be started while the SDT timing alignment timer is running. This connection SDT indication can be sent / multiplexed along with the initial CG-based UL SDT. This connection SDT indication can be included in control information (e.g., such as...). Figures 5A to 5EAt least one bit in the SDT MAC CE given in the code, a set of periodic / aperiodic PUCCH resources on the initial / default BWP or across different BWPs, a tail bit in the data payload, or carried along with the SDT. In some cases, if there is a SDT to be connected or new data is waiting to be sent to the network, but the UE may miss the transmission timing on the CG resource for some reason (e.g., due to an invalid TA value being used because of an RSRP change), the UE can send a SDT connection indication to request timing alignment. The SDT timing alignment timer can be started or restarted using SDT paging, such as... Figure 4A and 4B As shown. When maintaining UL synchronization / time alignment in the RRC_INACTIVE state, CG-based SDT and subsequent RACH-based / CG-based SDT can run in the RRC_INACTIVE state. Figure 19 A flowchart showing a method for transmitting small amounts of data in the RRC_INACTIVE state according to the fourteenth embodiment of this application is displayed. Figure 19 For networks supporting SDT in the RRC_INACTIVE state, the public / UE-specific SDT configurations are sent in the system information submitted above. For SDT UL authorization shared within the UE, the network can broadcast / unicast public / UE-specific SDT configurations (e.g., supported SDT types, SDT priorities, public / UE-specific SDT search spaces, public SDT thresholds, public SDT_RSRP thresholds, SDT paging configurations and search spaces, RACH-based SDT configurations, SDT PRACH configurations, etc.) through system information (e.g., SIB2, on-demand SI). Some UE-specific SDT configurations are sent in the RRC signaling mentioned above. For dedicated SDTs within a UE, the network can unicast UE-specific SDT configurations (e.g., supported SDT types, SDT priorities, UE-specific SDT thresholds, UE-specific SDT_RSRP thresholds, CG-based SDT configurations, SDT DL allocation configurations, SDT ran-Paging Cycles, I-RNTIs, SDT release reasons, etc.) via RRC signaling (e.g., RRC Release). Figure 19In the process, the RRCResumeRequest, which includes suspendConfig and UE-specific SDT configuration, is sent by the network to suspend or suspend the RRC connection. The UE should apply the received suspendConfig and UE-specific SDT configuration. The MAC entity is reset, so the timing alignment timer associated with the TAG stops or expires. After entering the RRC_INACTIVE state and the UL data arrives at the UE TX buffer, the UE can initiate a two-step or four-step RACH-based SDT to trigger the SDT timing alignment timer based on the SDT threshold. If the UE decides to initiate a two-step RACH-based SDT, a small amount of UL and optional DL data is transmitted on the MSGA and MSGB, respectively. In addition, the MSGA may include an RRCResumeRequest multiplexed with the SDT continuation indication, while the MSGB includes an RRCResumeRequest multiplexed with the SDT timing advance command MAC CE. The SDT timing alignment timer starts when the SDT timing advance command included in the MSGB is received. If the UE decides to initiate a four-step RACH-based SDT ( Figure 19 (Not shown in the image), then small amounts of UL and DL data are transmitted on MSG3 and MSG4 respectively. Furthermore, MSG3 may include an RRCresumeRequest multiplexed with the SDT continuation indication, while MSG4 may include an RRCrease multiplexed with DL data if necessary. The SDT timing alignment timer starts upon receiving an SDT time advance command included in MSG2. In some cases, the SDT continuation indication may indicate that additional SDTs are waiting to be sent to the network, and then the CG-based SDT can easily continue operating while maintaining UL timing alignment. In other cases, if the SDT continuation indication indicates that no further SDTs will be sent within a certain period, the network can determine whether to deactivate the SDT resources allocated to the UE and maintain the SDT timing alignment timer for the UE by employing SDT paging, such as... Figure 4A and 4B As shown. If the network decides to maintain CG-based resource allocation, CG-based SDT can be transmitted in a low-latency and low-power manner in the RRC_INACTIVE state. If the network decides to deactivate CG-based resource allocation, it can be activated when a follow-up SDT indication is received, for example, via PUCCH (not shown). For a period thereafter, the UE can still perform CG-based SDT while the SDT timing alignment timer is running. When maintaining UL synchronization / timing alignment in the RRC_INACTIVE state, both CG-based SDT and follow-up CG-based SDT can operate in the RRC_INACTIVE state. According to another aspect of the invention, when the NAS layer clears the SDT transmission, and UL data arrives from a higher layer, an SDT threshold is provided to the UE to determine whether to perform SDT in the RRC_INACTIVE state. When the UE's data volume exceeds the SDT threshold, the UE will enter the RRC_CONNECTED state to perform normal data transmission procedures. Otherwise, the UE can initiate CG-based or RACH-based SDT in the RRC_INACTIVE state. Upon receiving a recovery request from the UE, the network should initiate a UE context recovery procedure to reactivate the NAS connection. According to all embodiments, if the network is a RAN function split node, the transmission of UL / DL SDT can be cleared between the Central Unit (CU) and the Distributed Unit (DU) via the F1 interface and signaling. According to another aspect of the invention, when CA replication supports SDT in the RRC_INACTIVE state, the timing alignment timer of the sub-time advance group (sTAG) should be maintained by the network and the UE. When the UL synchronization / time alignment of the associated TAG is maintained in the RRC_INACTIVE state, a small amount of data can be transmitted in the RRC_INACTIVE state. According to another aspect of the invention, when considering the adaptation of SDT in the RRC_INACTIVE state to the Bandwidth Part (BWP), the network is configured with one or more BWPs. One or more specific BWPs (e.g., initial, default, active BWPs) are configured to transmit SDT in the RRC_INACTIVE state. BWP switching based on RACH-based SDT is used to transmit SDT in the RRC_INACTIVE state. UL / DL data can be transmitted on associated BWPs based on the bwp-Id / link of the same UL / DL BWP. Some embodiments offer the following commercial benefits: 1. Solving problems in the prior art. 2. Achieving UL synchronization / timing maintenance. 3. Improving resource utilization efficiency. 4. Improving power consumption and signaling overhead. 5. Providing superior communication performance. Some embodiments of this application are used by 5G-NR chipset suppliers, V2X communication system development suppliers, automobile manufacturers (including cars, trains, trucks, buses, bicycles, motorcycles, helmets, etc.), drone (unmanned aerial vehicle) manufacturers, smartphone manufacturers, communication equipment manufacturers for public safety purposes, and AR / VR device manufacturers (e.g., for gaming, conferences / seminars, educational purposes). Some embodiments of this application are combinations of "technologies / processes" that can be adopted in 3GPP specifications to develop terminal products. Some embodiments of this application can be used in 5G NR unlicensed frequency band communications. Some embodiments of this application propose technical solutions.

[0042] The main advantages of the method in this application include at least one of the following: Lower power consumption and smaller data transfer rates in RRC_INACTIVE state Lower data transmission latency in RRC_INACTIVE state UL Synchronization / Timing Maintenance in RRC_INACTIVE State 5G networks offer better resource utilization efficiency Lower signaling overhead and smaller data transmission in RRC_INACTIVE state Timing recovery of configured authorization The limited data transmission in the RRC_INACTIVE state takes into account RAN function splitting, carrier aggregation replication, and BWP adaptation. This application also provides a computer-readable storage medium for storing computer programs. This computer-readable storage medium enables a computer to execute the corresponding programs implemented by the UE / BS in the various methods of this application's embodiments; for the sake of brevity, these will not be elaborated upon here. This application also provides a computer program product, including computer program instructions. This computer program product enables a computer to execute the corresponding programs implemented by the UE / BS in the various methods of this application embodiment; for the sake of brevity, these will not be elaborated upon here. This application also provides a computer program. This computer program enables a computer to execute the corresponding programs implemented by the UE / BS in the various methods of this application embodiment, which will not be described in detail here for the sake of brevity. Those skilled in the art will recognize that, based on the examples described in the embodiments disclosed in this specification, the units and algorithm steps can be implemented by electronic hardware or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application conditions and design requirements of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but this implementation should not be considered to be beyond the scope of this application. Although this application has been described in conjunction with what are considered to be the most practical and preferred embodiments, it should be understood that this application is not limited to the disclosed embodiments, but is intended to cover various arrangements made without departing from the broadest interpretation of the appended claims.

Claims

1. A method for small data transmission (SDT) in RRC_INACTIVE state, performed by user equipment (UE) in the network, the method comprising: Receive a Radio Resource Control (RRC) release message for providing SDT configuration, and a first timing advance (TA) command sent together with the RRC release message; Upon receiving the RRC release message, apply the first TA command; as well as Upon receiving the first TA command sent along with the RRC release message, start or restart the Timing Alignment Timer (TAT) to maintain uplink (UL) timing alignment during SDT in the RRC_INACTIVE state.

2. The method according to claim 1, further comprising: When a second TA command is received in the RRC_INACTIVE state, the TAT is restarted.

3. The method of claim 2, wherein the second TA command is carried by a Media Access Control (MAC) control element (CE).

4. The method of claim 2, wherein the second TA command is sent together with the SDT paging message.

5. The method of claim 2, wherein the second TA command is included in a random access response (RAR) message from the network.

6. The method of claim 2, wherein the second TA command is multiplexed with downlink (DL) data.

7. The method of claim 2, wherein the reception of the second TA command in the RRC_INACTIVE state is achieved in the following manner: Send a continuation SDT indication for requesting time alignment; and The second TA command is received in response to the continuation SDT instruction.

8. The method of claim 1, wherein the TAT is an SDT TAT specific to the SDT performed in the RRC_INACTIVE state.

9. The method of claim 1, wherein the TAT is associated with one or more Timing Advance Groups (TAGs).

10. The method of claim 1, wherein the SDT configuration includes an SDT threshold for the UE to determine which SDT type to apply in the RRC_INACTIVE state.

11. The method according to any one of claims 1 to 10, further comprising: After entering the RRC_INACTIVE state, when the TAT receives the first TA command while running, the TAT is started or restarted to perform the uplink (UL) initial SDT based on the configured grant (CG); and Following the initial CG-based SDT, subsequent CG-based SDTs are executed.

12. The method of claim 11, further comprising: If no TA command is received from the network after a period of time, a RACH-based SDT is executed after the initial CG-based SDT.

13. The method of claim 11, further comprising: Receive downlink (DL) data, which is transmitted on pre-configured DL allocated resources or multiplexed with SDT paging messages, wherein the TA command MAC CE is replied by the MAC header of the DL data or multiplexed with the SDT paging message.

14. The method of claim 11, further comprising: If the resource transfer timing based on CG is missed, the CG-based SDT is executed after the RACH-based SDT. After updating the TAT via RACH-based SDT, the CG-based resource is reactivated, and the CG-based SDT is transmitted over the CG-based resource.

15. The method according to any one of claims 1 to 10, further comprising: Upon entering the RRC_INACTIVE state, the initial RACH-based SDT is executed regardless of whether the TAT is running.

16. The method of claim 1, further comprising: Send a Connection SDT instruction to the network to request the TAT to be restarted in the RRC_INACTIVE state.

17. The method of claim 16, wherein the continuation SDT instruction is included in the MSGA of a two-step RACH SDT or in the MSG3 of a four-step RACH SDT.

18. A method for small data transmission (SDT) in RRC_INACTIVE state, performed by a base station (BS) in the network, the method comprising: The Radio Resource Control (RRC) release message used to provide SDT configuration, along with the first timing advance (TA) command sent together with the RRC release message, is sent to the user equipment (UE). It is expected that the UE will apply the first TA command upon receiving the RRC release message; as well as It is expected that when the UE receives the first TA command sent along with the RRC release message, it will start or restart the Timing Alignment Timer (TAT) to maintain uplink (UL) timing alignment during SDT in the RRC_INACTIVE state.

19. A user equipment comprising a memory, a transceiver, and a processor coupled to the memory and the transceiver, the processor being configured to invoke and execute program instructions stored in the memory to perform the method according to any one of claims 1 to 17.

20. A base station comprising a memory, a transceiver, and a processor coupled to the memory and the transceiver, the processor being configured to invoke and execute program instructions stored in the memory to perform the method of claim 18.

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