Small data transmission method and related equipment

Abstract

A method and user equipment (UE) for small data transmission are provided. The method includes: receiving a radio resource control (RRC) release message from a base station (BS), the RRC release message including a configured grant (CG) configuration and a first timer associated with the CG configuration, the CG configuration indicating an uplink (UL) resource; in response to receiving the RRC release message, transitioning to an RRC_INACTIVE state; in response to receiving the RRC release message, starting the first timer; determining whether the UL resource is valid, the UL resource being invalid at least when the first timer expires; and transmitting UL data on the UL resource after the UE determines that the UL resource is valid.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This disclosure claims the benefit of and priority to U.S. Provisional Patent Application Serial No. 62 / 955,718, filed on December 31, 2019 (“the '718 Provisional”), entitled “Mechanism for Small Data Transmission.” The contents of the '718 Provisional are incorporated herein by reference in their entirety. Technical Field

[0003] The present disclosure relates generally to wireless communications, and more particularly, to methods and apparatus for small data transmission. Background Art

[0004] With the tremendous growth in the number of connected devices and the rapid increase in user / network traffic, various efforts have been made to improve various aspects of wireless communications for next-generation wireless communication systems, such as fifth-generation (5G) New Radio (NR), by increasing data rates, latency, reliability, and mobility.

[0005] The 5G NR system is designed to provide flexibility and configurability to optimize network services and types to accommodate various use cases such as enhanced mobile broadband (eMBB), massive machine-type communications (mMTC), and ultra-reliable low-latency communications (URLLC).

[0006] However, as the demand for radio access continues to increase, wireless communications for next generation wireless communication systems need to be further improved. Summary of the Invention

[0007] The present disclosure relates generally to wireless communications, and more particularly, to methods and apparatus for small data transmission.

[0008] According to one aspect of the present disclosure, a method for performing small data transmission by a user equipment (UE) is provided, the method comprising: receiving a radio resource control (RRC) release message from a base station (BS), the RRC release message including a configured grant (CG) configuration and a first timer associated with the CG configuration, the CG configuration indicating an uplink (UL) resource; in response to receiving the RRC release message, transitioning to an RRC_INACTIVE state; in response to receiving the RRC release message, starting the first timer; determining whether the UL resource is valid, the UL resource being invalid at least when the first timer expires; and transmitting UL data on the UL resource after the UE determines that the UL resource is valid.

[0009] According to another aspect of the present disclosure, a UE for performing small data transmission is provided, the UE comprising: at least one processor; and at least one memory coupled to the at least one processor, the at least one memory storing computer-executable instructions, which, when executed by the at least one processor, cause the UE to perform the above-mentioned method for performing the small data transmission. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Various aspects of the present disclosure are best understood from the following detailed description when read in conjunction with the accompanying drawings. Various features are not drawn to scale. The dimensions of various features may be arbitrarily increased or decreased for clarity of discussion.

[0011] Figure 1 is a flow chart illustrating a fallback method according to one embodiment of the present disclosure.

[0012] Figure 2 FIG. 1 is a flowchart illustrating small data transmission according to one embodiment of the present disclosure.

[0013] Figure 3 is a block diagram illustrating wireless communication according to one embodiment of the present disclosure. DETAILED DESCRIPTION

[0014] The following description contains specific information related to exemplary embodiments of the present disclosure. The drawings and the accompanying detailed disclosure are directed only to exemplary embodiments. However, the present disclosure is not limited to these exemplary embodiments. Other variations and embodiments of the present disclosure will occur to those skilled in the art. Unless otherwise indicated, identical or corresponding elements in the drawings may be represented by similar or corresponding reference designators. In addition, the drawings and illustrations in the present disclosure are generally not drawn to scale and are not intended to correspond to actual relative dimensions.

[0015] For consistency and ease of understanding, similar features are identified by numbers in the example figures (although not shown in some examples). However, features in different embodiments may be different in other aspects and should not be narrowly limited to the features shown in the figures.

[0016] The phrases "in one embodiment" and "in some exemplary embodiments" may refer to one or more identical or different embodiments. The term "coupled" is defined as connected directly or indirectly through intermediate components and is not necessarily limited to physical connections. The term "comprising," when used to mean "including but not necessarily limited to," expressly indicates open inclusion or membership in the disclosed combinations, groups, series, and equivalents.

[0017] The term "and / or" is used herein only to describe the relationship between related objects and indicates that three possible relationships exist. For example, "A and / or B" can mean: A exists alone, A and B exist simultaneously, and B exists alone. "A and / or B and / or C" can mean that at least one of A, B, and C exists. The character " / " used herein generally indicates that the former and the latter related objects are in an "or" relationship.

[0018] In addition, any two or more of the following paragraphs, (sub)items, key points, actions, behaviors, terms, alternatives, examples, or claims in this disclosure can be logically, reasonably, and appropriately combined to form a specific method. Any sentence, paragraph, (sub)item, key point, action, behavior, term, or claim in this disclosure can be implemented separately to form a specific method. Dependencies in this disclosure, such as, "based on," "more specifically," "preferably," "in one embodiment," "in one implementation," "in an alternative," may refer only to one possible example but are not limited to a specific method.

[0019] For the purpose of non-limiting explanation, specific details such as functional entities, technologies, protocols, standards, etc. are set forth to provide an understanding of the disclosed technology. In other instances, detailed disclosure of well-known methods, technologies, systems, architectures, and the like are omitted to avoid obscuring the disclosure with unnecessary detail.

[0020] Those skilled in the art will immediately recognize that any (one or more) network functions or (one or more) algorithms can be implemented by hardware, software, or a combination of software and hardware. The disclosed functions can correspond to modules, which can be software, hardware, firmware, or any combination thereof. Software implementations can include computer-executable instructions stored on a computer-readable medium such as a memory or other type of storage device. For example, one or more microprocessors or general-purpose computers with communication processing capabilities can be programmed with corresponding executable instructions and execute the disclosed (one or more) network functions or (one or more) algorithms. The microprocessor or general-purpose computer can be composed of application-specific integrated circuits (ASICs), programmable logic arrays, and / or one or more digital signal processors (DSPs). Although some of the disclosed example embodiments are directed to software installed and executed on computer hardware, alternative example embodiments implemented as firmware or hardware, or a combination of hardware and software, are within the scope of this disclosure.

[0021] Computer-readable media include, but are not limited to, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), flash memory, compact disc read-only memory (CD-ROM), magnetic tape cassettes, magnetic tapes, disk storage devices, or any other equivalent medium that can store computer-readable instructions.

[0022] A radio communication NW architecture (such as a Long-Term Evolution (LTE) system, an Advanced LTE (LTE-Advanced, LTE-A) system, an Advanced LTE Pro system, or a New Radio (NR) system) typically includes at least one base station (BS), at least one UE, and one or more optional network elements that provide connections within the network. The UE communicates with a network (such as a Core Network (CN), an Evolved Packet Core (EPC) network, an Evolved Universal Terrestrial Radio Access Network (E-UTRAN), a Next-Generation Core (NGC), a 5G Core (5G Core, 5GC) or the Internet) via a Radio Access Network (RAN) established by one or more BSs.

[0023] It should be noted that in the present disclosure, a UE may include, but is not limited to, a mobile station, a mobile terminal or device, or a user communication radio terminal. For example, a UE may be a portable radio device, including, but not limited to, a mobile phone, a tablet, a wearable device, a sensor, or a personal digital assistant (PDA) with wireless communication capabilities. A UE may be configured to receive signals over an air interface and to transmit signals to one or more cells in a RAN.

[0024] The BS may include, but is not limited to, a Node B (NB) in the Universal Mobile Telecommunication System (UMTS), an evolved Node B (eNB) in LTE-A, a Radio Network Controller (RNC) in UMTS, a Base Station Controller (BSC) in the Global System for Mobile communication (GSM) / GERAN (Edge Radio Access Network), a next-generation eNB (ng-eNB) in the E-UTRABS connected to the 5GC, a next-generation Node B (gNB) in the 5G Access Network (5G-AN), and any other device capable of controlling radio communications and managing radio resources within a cell. The BS may be connected to the NW via a radio interface to serve one or more UEs.

[0025] The BS may be configured to provide communication services based on at least one of the following radio access technologies (RATs): Worldwide Interoperability for Microwave Access (WiMAX), GSM (commonly referred to as 2G), GERAN, General Packet Radio Service (GPRS), UMTS based on basic Wideband-Code Division Multiple Access (W-CDMA) (commonly referred to as 3G), High-Speed ​​Packet Access (HSPA), LTE, LTE-A, enhanced LTE (eLTE), NR (commonly referred to as 5G), and LTE-A Pro. However, the scope of the present disclosure should not be limited to the above protocols.

[0026] The BS may be operable to provide radio coverage to a specific geographical area using multiple cells included in the RAN. The BS may support the operation of cells. Each cell may be operable to provide services to at least one UE within its radio coverage. More specifically, each cell (commonly referred to as a serving cell) may provide services to one or more UEs within its radio coverage (for example, each cell schedules downlink (DL) resources and optional uplink (UL) resources to at least one UE within its radio coverage for DL ​​and optional UL packet transmission). The BS may communicate with one or more UEs in a radio communication system through multiple cells. The cell may allocate sidelink (SL) resources to support proximity services (ProSe), LTE SL services, and LTE / NR vehicle-to-everything (V2X) services. Each cell may have a coverage area that overlaps with other cells. In the case of Multi-RAT Dual Connectivity (MR-DC), the master cell of the Master Cell Group (MCG) or the Secondary Cell Group (SCG) may be referred to as a Special Cell (SpCell). The Primary Cell (PCell) may refer to the SpCell of the MCG. The Primary SCG Cell (PSCell) may refer to the SpCell of the SCG. The MCG may refer to a group of service cells associated with the Master Node (MN), including the SpCell and optionally one or more Secondary Cells (SCell). The SCG may refer to a group of service cells associated with the Secondary Node (SN), including the SpCell and optionally one or more SCells.

[0027] As previously disclosed, the frame structure of NR supports flexible configuration to adapt to various next-generation (e.g., 5G) communication requirements such as eMBB, mMTC, and URLLC, while meeting high reliability, high data rate, and low latency requirements. The Orthogonal Frequency-Division Multiplexing (OFDM) technology agreed in the 3rd Generation Partnership Project (3GPP) can be used as the baseline for the NR waveform. Scalable OFDM parameter sets such as adaptive subcarrier spacing, channel bandwidth, and cyclic prefix (CP) can also be used. Additionally, two coding schemes are applied to NR: (1) Low-Density Parity-Check (LDPC) and (2) polarization codes. The coding scheme adaptability can be configured based on channel conditions and / or service applications.

[0028] In addition, it should be considered that the transmission time interval of a single NR frame should include at least DL transmission data, guard period, and UL transmission data, where the various parts of DL transmission data, guard period, and UL transmission data should also be configurable, for example, based on NR's NW dynamics. In addition, SL resources can also be provided in NR frames to support ProSe services or V2X services.

[0029] To save UE power and reduce data transmission latency, NR introduces a new RRC state (e.g., the inactive state (RRC_INACTIVE state)). The RRC_INACTIVE state is a state in which the UE remains connected to the connection management (CM-CONNECTED) and can move within the area configured by the NG-RAN (e.g., the RAN Notification Area (RNA)) without notifying the NG-RAN. When the UE is in the RRC_INACTIVE state, the last serving gNB maintains the UE context and the NG connection associated with the UE with the serving Access and Mobility Management Function (AMF) and User Plane Function (UPF).

[0030] In addition, a two-step random access (RA) procedure has been introduced in NR to facilitate faster transitions from the RRC_IDLE state to the RRC_CONNECTED state, or from the RRC_INACTIVE state to the RRC_CONNECTED state. As described in 3GPP TS 38.300 v15.7.0, the MSGA of contention-based two-step random access (CBRA) consists of a preamble on the physical random access channel (PRACH) and a payload on the physical uplink shared channel (PUSCH). After the MSGA transmission, the UE monitors for a response from the network within a configured window. If contention resolution is successful upon receiving a network response, the UE terminates the RA procedure. If a fallback indication is received in the MSGB of the two-step CBRA, the UE performs an MSG3 transmission and monitors the physical downlink shared channel (PDSCH) for contention resolution. On the other hand, if contention resolution is unsuccessful after MSG3 transmission, the UE reverts to MSGA transmission. Note that MSGA is represented as the preamble and payload transmission of the two-step RA process. MSGB is represented as the response to MSGA. MSGB can include a response for contention resolution, a fallback indication, and a backoff indication.

[0031] In NR (as introduced in 3GPP TS 38.321 v15.7.0), there are two types of transmissions without dynamic grants:

[0032] -Configured Grant (CG) Type 1, where the UL grant is provided by an RRC entity (e.g., the RRC entity of the gNB) and stored as a configured UL grant by the UE's Medium Access Control (MAC) entity. Specifically, for CG Type 1, the RRC entity directly provides the configured UL grant (including periodicity).

[0033] -CG Type 2, where the UL grant is provided by the Physical Downlink Control Channel (PDCCH) (e.g., from the gNB to the UE), and the configured uplink grant is stored or cleared based on L1 signaling (by the UE's MAC entity), which indicates the activation or deactivation of the configured UL grant. Specifically, for CG Type 2, when the PDCCH addressed by the configured Scheduling-Radio Network Temporary Identifier (CS-RNTI) can activate the configured UL grant or deactivate the configured UL grant, the RRC entity defines the period of the configured UL grant. For example, the PDCCH addressed by the CS-RNTI indicates that the UL grant can be implicitly reused according to the period defined by the RRC entity until deactivated.

[0034] With CG, the UE can transmit UL data more efficiently because the UE does not need to request (dynamic) UL grants through the Scheduling Request (SR) process and the Buffer Status Report (BSR). Note that CG is only supported when the UE is in the RRC_CONNECTED state.

[0035] Currently, UEs with infrequent (periodic and / or aperiodic) data transmission are typically kept in the RRC_INACTIVE state by the network (NW) to save UE power and shorten data transmission delays. Prior to 3GPP Release 16, a UE in the RRC_INACTIVE state could not directly transmit UL data. That is, for UL data transmission, the UE needs to restore the connection (e.g., transition from the RRC_INACTIVE state to the RRC_CONNECTED state). In each UL data transmission, even for small data transmissions, connection setup (or recovery) and subsequent release (or suspension) to the RRC_INACTIVE state may also occur. Therefore, this can lead to unnecessary power consumption and signaling overhead on both the UE side and the NW side.

[0036] To support small data transmission in the RRC_INACTIVE state, a random access channel (RACH)-based scheme for small data transmission (eg, a 2-step RA procedure or a 4-step RA procedure) or pre-configured PUSCH resources for small data transmission is disclosed.

[0037] Methods for transmitting UL data via an RA procedure in an RRC_INACTIVE state, transmitting UL data via preconfigured PUSCH resources in an RRC_INACTIVE state, providing preconfigured PUSCH resources in an RRC_INACTIVE state, determining valid preconfigured PUSCH resources for small data transmission, and falling back to a RACH-based scheme from preconfigured PUSCH resources for small data transmission are disclosed below.

[0038] Small data transmission via the RA process

[0039] In some embodiments, an RA procedure (e.g., a 2-step RA procedure or a 4-step RA procedure) is triggered for small data transmission in the RRC_INACTIVE state (e.g., an RA procedure associated with an RRC recovery procedure for small data transmission). In some embodiments, if the NW (e.g., BS) configures / indicates / allows the RA procedure for small data transmission through system information, dedicated signaling, or in an RRC release message with a suspension configuration, the RA procedure for small data transmission (e.g., a 2-step RA procedure or a 4-step RA procedure) may be triggered in the RRC_INACTIVE state. When the UE receives an RRC release message with a suspension configuration, the UE may transition from the RRC_CONNECTED state to the RRC_INACTIVE state, or when the UE receives an RRC release message with a suspension configuration, the UE may remain in the RRC_INACTIVE state. In some embodiments, in order to apply the RA procedure for small data transmission in a cell configured with a supplementary uplink (SUL), the BS may explicitly signal the carrier to be used (e.g., UL or SUL). In some embodiments, to apply the RA procedure for small data transmission in a cell configured with SUL, the BS may explicitly signal whether the SUL is used for small data transmission. In some embodiments, to apply the RA procedure for small data transmission in a cell configured with SUL or configured with UL and SUL, the UE may be pre-configured (or defaulted) to perform small data transmission via the RA procedure on a carrier (e.g., a UL carrier, a SUL carrier, a high frequency carrier, or a low frequency carrier).

[0040] In some embodiments, UL data (e.g., small data) may be transmitted in MSG3 of a 4-step RA procedure via a UL grant (or associated random access response (RAR)) received in MSG2. In some embodiments, an indication may be included in (or used in) MSG3 to indicate that the RA procedure (e.g., the 4-step RA procedure) is used for small data transmission. For example, the RRC recovery request message carried in MSG3 may include an indication to indicate that the associated RRC recovery procedure is used for small data transmission. In another example, the absence of an indication in the RRC recovery request message carried in MSG3 may mean that the associated RRC recovery procedure is used for normal purposes (e.g., not for small data transmission). In some embodiments, an indication may be included in (or used in) MSG3 to indicate whether the small data transmission is complete. For example, if the indication is set to true, the BS may assume that the small data transmission is complete and may not further configure the UL grant (e.g., via MSG4). On the other hand, if the indication is set to false (or does not exist or disappears), the BS may consider that the small data transmission has not been completed (e.g., subsequent data transmission is required) and may configure a subsequent UL grant to the UE (e.g., via MSG4 or via an RRC release message with a pause configuration), or may command the UE to transition back to the RRC_CONNECTED state. Note that the RRC release message with a pause configuration may include pre-configured PUSCH configuration / resources for subsequent data transmission. In another example, if the indication is set to false (or does not exist or disappears), the BS may consider that the small data transmission has been completed and may not further configure UL grant (e.g., via MSG4). On the other hand, if the indication is set to true, the BS may consider that the small data transmission has not been completed (e.g., subsequent data transmission is required) and may configure a subsequent UL grant to the UE (e.g., via MSG4 or via an RRC release message with a pause configuration), or may command the UE to transition back to the RRC_CONNECTED state. Note that the RRC release message with a pause configuration may include pre-configured PUSCH configuration / resources for subsequent data transmission. The above-mentioned settings for the indication (e.g., true / false) may be applied to embodiments of the present disclosure. In some embodiments, the indication may be included in (or used in) another UL grant (e.g., a subsequent UL grant configured by the BS) to indicate whether the small data transmission is complete. For example, the UE may send the indication in the same PUSCH resource in which it sends the small data, and the indication may correspond to the small data. Note that the indication may be sent after the corresponding small data in the same PUSCH resource.Therefore, if the indication is set to false (or does not exist or disappears), the UE may further receive an UL grant (e.g., via MSG4, via downlink control information (DCI), or via dedicated signaling) for subsequent small data transmission. In some embodiments, the BS may indicate via RRC signaling (e.g., system information or an RRC release message with a suspension configuration) whether the UE in the RRC_INACTIVE state is allowed to perform a 4-step RA process for small data transmission. For example, the cell may broadcast an indication via system information to indicate whether the UE is allowed to transmit small data in the RRC_INACTIVE state via a 4-step RA process. A UE that receives system information indicating that the UE is allowed to perform small data transmission in the RRC_INACTIVE state may perform small data transmission when the UE enters the RRC_INACTIVE state. In addition, when the UE enters the RRC_INACTIVE state, the UE that receives system information indicating that the UE is allowed to perform small data transmission in the RRC_INACTIVE state may perform small data transmission via a 4-step RA process. In another example, the UE may receive an indication via dedicated signaling (e.g., in an RRC release message with a pause configuration) indicating whether the UE is allowed to send small data in the RRC_INACTIVE state via a 4-step RA procedure. A UE that receives dedicated signaling indicating that the UE is allowed to perform small data transmission in the RRC_INACTIVE state may perform small data transmission when the UE enters the RRC_INACTIVE state. In addition, when the UE enters the RRC_INACTIVE state, a UE that receives dedicated signaling indicating that the UE is allowed to perform small data transmission in the RRC_INACTIVE state may perform small data transmission via a 4-step RA procedure.

[0041] In some embodiments, UL data (e.g., small data) may be transmitted in the PUSCH payload of the MSGA in a 2-step RA procedure. In some embodiments, the small data transmitted directly in the PUSCH payload of the MSGA may implicitly inform the gNB that the RA procedure (e.g., a 2-step RA procedure) is for small data transmission. In some embodiments, an indication may be included in (or used in) the MSGA to indicate that the RA procedure is for small data transmission. For example, an RRC Recovery Request message carried in the MSGA may include an indication indicating that the associated RRC Recovery procedure is for small data transmission. In another example, an RRC Recovery Request message carried in the MSGA without an indication may indicate that the associated RRC Recovery procedure is used for normal purposes (e.g., not for small data transmission). In some embodiments, an indication may be included in (or used in) the MSGA to indicate whether the small data transmission is complete. For example, if the indication is set to true, the BS may assume that the small data transmission is complete and may not further configure an UL grant (e.g., via the MSGB). Note that the small data transmission indicated by (or associated with) the indication in the MSGA can be a small data transmission in the PUSCH of the MSGA of a 2-step RA procedure, or can be a small data transmission performed by or in a previous RA procedure, where the RA procedure can be a 2-step RA procedure, a 4-step RA procedure, or a 2-step RA procedure with fallback to a 4-step RA procedure. For example, if the indication is set to false (or absent or disappears), the BS may assume that the small data transmission is not yet complete (e.g., subsequent data transmission is required) and may configure a subsequent UL grant to the UE (e.g., via the MSGB or via an RRC Release message with a pause configuration), or may command the UE to transition back to the RRC_CONNECTED state. Note that the RRC Release message with a pause configuration may include the preconfigured PUSCH configuration / resources for subsequent data transmission. In some embodiments, the indication may be included in other UL grants (e.g., the subsequent UL grant is configured by the BS) to indicate whether the small data transmission is complete. For example, the UE may send the indication in the same PUSCH resource in which it sent the small data, and the indication may correspond to the small data. Note that the indication may be transmitted after the corresponding small data in the same PUSCH resource. Therefore, if the indication is set to false (or does not exist or disappears), the UE may further receive an UL grant (e.g., via MSGB, via DCI, or via dedicated signaling) for subsequent small data transmission. In some embodiments, the B BS may indicate via RRC signaling (e.g., system information or an RRC release message with a suspension configuration) whether a UE in the RRC_INACTIVE state is allowed to perform a 2-step RA procedure for small data transmission.For example, a cell may broadcast an indication via system information to indicate whether the UE is allowed to transmit small data in the RRC_INACTIVE state via a 2-step RA procedure. When the UE enters the RRC_INACTIVE state, the UE that receives the system information indicating that the UE is allowed to transmit small data in the RRC_INACTIVE state may perform small data transmission. In addition, when the UE enters the RRC_INACTIVE state, the UE that receives the system information indicating that the UE is allowed to transmit small data in the RRC_INACTIVE state may perform small data transmission via a 2-step RA procedure. In another example, the UE may receive an indication via dedicated signaling (e.g., in an RRC release message with a suspension configuration) indicating whether the UE is allowed to transmit small data in the RRC_INACTIVE state via a 2-step RA procedure. When the UE enters the RRC_INACTIVE state, the UE that receives the dedicated signaling indicating that the UE is allowed to transmit small data in the RRC_INACTIVE state may perform small data transmission. In addition, when the UE enters the RRC_INACTIVE state, the UE that receives the dedicated signaling indicating that the UE is allowed to transmit small data in the RRC_INACTIVE state may perform small data transmission via a 2-step RA procedure.

[0042] In some embodiments, a UE (e.g., in an RRC_CONNECTED state or in an RRC_INACTIVE state) may receive an RRC release message with a suspension configuration, which indicates an allowed logical channel or data radio bearer (DRB). The allowed logical channel or DRB may be a logical channel or DRB allowed for UL data transmission in the RRC_INACTIVE state. Specifically, small data transmission may be configured per DRB. In some embodiments, only UL data associated with the allowed logical channel or DRB may be transmitted through an RA procedure for small data transmission or an RRC procedure for small data transmission. In some embodiments, if the UE receives an RRC release message including a suspension configuration and indicates the allowed logical channels or DRBs (e.g., in an RRC release message including the suspension configuration), the UE (or the UE's RRC entity) may suspend all SRBs and DRBs except SRB 0 and allowed DRBs. The UE (or the UE's RRC entity) may instruct a lower layer to suspend a Packet Data Convergence Protocol (PDCP) entity for all DRBs except the allowed DRBs. In some embodiments, if the UE receives an RRC release message including a suspension configuration and an allowed logical channel or DRB is indicated (e.g., in the RRC release message including the suspension configuration), the UE (or the UE's RRC entity) may still suspend all SRBs and DRBs except SRB 0. The UE (or the UE's RRC entity) may still instruct the lower layer to suspend the PDCP entity for all DRBs. In this case, the allowed DRBs may be resumed (or reestablished) when there is UL data belonging to the allowed DRBs and / or small data transmission in the RRC_INACTIVE state is applicable (through the RA process or through the CG). Note that the allowed DRBs may be DRBs used for small data transmission in the RRC_INACTIVE state. The allowed DRBs may be preconfigured to the UE (e.g., preconfigured parameters of the Service Data Adaptation Protocol (SDAP) entity, PDCP entity, and / or 5G Quality of Service (QoS) Indicator (5QI) for the allowed DRBs). The allowed DRBs may be configured to the UE via dedicated signaling from the BS (e.g., RRC release with suspension configuration).

[0043] In some embodiments, the UE may receive an RRC release message with a suspension configuration, which indicates a disallowed logical channel or DRB in the RRC_INACTIVE state. That is, data associated with the disallowed logical channel or DRB cannot be transmitted via the RA process. In some embodiments, if an RRC release message including a suspension configuration is received and a disallowed logical channel or DRB is indicated (for example, in an RRC release message including a suspension configuration), the UE may suspend all SRBs and disallowed DRBs except SRB 0. The UE cannot suspend other DRBs. The UE (or the RRC entity of the UE) may instruct the lower layers of the disallowed DRB to suspend the PDCP entity. The UE (or the RRC entity of the UE) may not instruct the lower layers of the other DRBs to suspend the PDCP entity. In some embodiments, if an RRC release message including a suspension configuration is received and a disallowed logical channel or DRB is indicated (for example, in an RRC release message including a suspension configuration), the UE may still suspend all SRBs and DRBs except SRB 0. The UE (or the RRC entity of the UE) can still instruct the lower layer to suspend the PDCP entity for all DRBs. In this case, when there is UL data belonging to the disallowed DRB and / or small data transmission in the RRC_INACTIVE state is applicable (through the RA process or through the CG), the disallowed DRB can be restored (or re-established). Note that the disallowed DRB may be a DRB that is not allowed to perform small data transmission in the RRC_INACTIVE state. The disallowed DRB may be pre-configured to the UE (e.g., pre-configured parameters of the SDAP entity, PDCP entity and / or 5QI for the disallowed DRB). The disallowed DRB may be configured to the UE by dedicated signaling from the BS (e.g., RRC release with suspension configuration).

[0044] Note that when higher layers request the PDCP entity to be suspended, the transmitting PDCP entity may set TX_NEXT to an initial value. TX_NEXT is a state variable that indicates the COUNT value of the next PDCP service data unit (SDU) to be transmitted, and its initial value is set to "0". The COUNT value consists of the hyperframe number (HFN) and the PDCP sequence number (SN). The size of the HFN part in bits is equal to 32 minus the length of the PDCP SN. It should also be noted that when higher layers request the PDCP entity to be suspended, the transmitting PDCP entity may discard all stored PDCP protocol data units (PDUs).

[0045] In some embodiments, if the UE receives an RRC release message including a suspension configuration and implicitly or explicitly indicates that small data transmission is allowed in the RRC_INACTIVE state as described above, the UE may suspend all SRBs and DRBs except SRB 0 and the default DRB. The UE (or the UE's RRC entity) may instruct the lower layer of the DRB other than the default DRB to suspend the PDCP entity. The UE may be (pre)configured by the BS with a default DRB that can be used for small data transmission. In some embodiments, the default DRB may be predefined or may be associated with a PDU session. In some embodiments, an indication may be included in the RRC release message to indicate that the UE is allowed to transmit small data in the RRC_INACTIVE state. In some embodiments, an indication may be included in the RRC release message to indicate that the UE is allowed to transmit small data via an RA procedure (e.g., a 2-step RA procedure, a 4-step RA procedure, a 2-step RA procedure falling back to a 4-step RA procedure) in the RRC_INACTIVE state. In some embodiments, an indication may be included in the RRC release message to indicate that the UE is allowed to transmit small data via any available RA procedure. In some embodiments, an indication may be included in the RRC release message (or in the suspension configuration of the RRC release message) to indicate that the UE is allowed to transmit small data via the 2-step RA procedure in the RRC_INACTIVE state. In some embodiments, an indication may be included in the RRC release message (or in the suspension configuration of the RRC release message) to indicate that the UE is allowed to transmit small data via the 4-step RA procedure in the RRC_INACTIVE state.

[0046] In some embodiments, if the UE receives an RRC release message including a suspension configuration and indicating the allowed logical channels or DRBs, the UE (or the RRC entity of the UE) may not suspend all DRBs and may not instruct the lower layers to suspend the PDCP entity for all DRBs. In some embodiments, if the UE receives an RRC release message including a suspension configuration and indicating the allowed logical channels or DRBs, the UE (or the RRC entity of the UE) may not suspend any DRBs and may not instruct the lower layers to suspend the PDCP entity for all DRBs.

[0047] In some embodiments, only UL data associated with an allowed logical channel or DRB may be transmitted through a RA procedure for small data transmission (e.g., a 2-step RA procedure, a 4-step RA procedure, or a 2-step RA procedure falling back to a 4-step RA procedure) or through an RRC procedure for small data transmission. For example, when the UE is in the RRC_INACTIVE state and the UL data belongs to an allowed logical channel or DRB, the UE may perform a RA procedure (or an associated RRC procedure) for small data transmission. Note that if the RA procedure (or an associated RRC procedure) for small data transmission is performed, the UE may not need to transition to an RRC connected state. In some embodiments, if there is UL data that is not associated with the allowed logical channel or DRB, the UE may need to transmit an RRC recovery request message to the BS (e.g., initiate a normal RRC recovery procedure). The UE may receive the RRC recovery message transmitted from the BS and transition to the RRC_CONNECTED state for small data transmission. In some embodiments, only UL data associated with an allowed logical channel or DRB can trigger an RA procedure for small data transmission (e.g., a 2-step RA procedure, a 4-step RA procedure, or a 2-step RA procedure falling back to a 4-step RA procedure), or by initiating an RRC procedure for small data transmission. If there is other UL data that is not associated with the allowed logical channel or DRB, and if there is still available space on the UL grant, the UE may also transmit other UL data that is not associated with the allowed logical channel or DRB on the same UL grant for small data transmission. Note that how to accommodate other UL data that is not associated with the allowed logical channel or DRB on the same UL grant (or the remaining space on the same UL grant) depends on the logical channel priority mechanism.

[0048] Small data transmission via CG

[0049] In some embodiments, the BS may provide the CG (e.g., pre-configured PUSCH resources, CG type 1 configuration) in dedicated signaling (e.g., in an RRC release message with a suspend configuration). Note that in the present disclosure, CG, pre-configured PUSCH resources, and CG type 1 configuration may be interchangeable. If a UE in the RRC_INACTIVE state is configured with pre-configured PUSCH resources, the UE may be allowed to transmit small data on the pre-configured PUSCH resources in the RRC_INACTIVE state without transitioning to the RRC_CONNECTED state. In some embodiments, when CG type 1 in the RRC_INACTIVE state is configured, the BS may configure the following parameters:

[0050] - Periodicity: CG type 1 periodicity;

[0051] -timeDomainOffset: the offset of the resource in the time domain relative to the system frame number (SFN) = 0;

[0052] -timeDomainAllocation: allocates the configured uplink grant in the time domain containing StartSymbolLandLength (i.e. SLIV in TS 38.214v15.7.0);

[0053] -nrofHARQ-Processes: Number of HARQ (Hybrid Automatic Repeat Request) processes of CG.

[0054] In some embodiments, if the configured Scheduling Radio Network Temporary Identifier (CS-RNTI) (or other RNTI) is not configured in the CG Type 1 configuration for a UE in the RRC_INACTIVE state, small data (re)transmission is not supported in the RRC_INACTIVE state. In some embodiments, if the CS-RNTI (or other RNTI) is configured in the CG Type 1 configuration for a UE in the RRC_INACTIVE state, small data (re)transmission in the RRC_INACTIVE state may be supported. In some embodiments, if small data retransmission in the RRC_INACTIVE state is supported, the UE in the RRC_INACTIVE state may monitor the common PDCCH (or common control resource set (CORESET)) addressed by the CS-RNTI (or other RNTI) if the UE in the RRC_INACTIVE state is configured with PUSCH resources for small data transmission in the RRC_INACTIVE state. In some embodiments, if a UE in RRC_INACTIVE state is configured with PUSCH resources for small data transmission in RRC_INACTIVE state, the UE in RRC_INACTIVE state may monitor the common PDCCH (or common CORESET) addressed by the CS-RNTI (or other RNTI) to deactivate or activate the pre-configured PUSCH resources.

[0055] In some embodiments, the BS may provide pre-configured PUSCH resources with different sizes and periods. For example, one or more CG configurations may be provided to the UE by the BS in dedicated signaling. In some embodiments, a UE in RRC_INACTIVE state configured with one or more CG configurations for small data transmission may determine which configured resource (e.g., PUSCH resource) to use based on the small data size in the buffer and the size of the configured resources (e.g., PUSCH resources). For example, CG configuration #1 may be configured with a grant size of 200 bits and CG configuration #2 may be configured with a grant size of 800 bits. If the small data size is less than or equal to 200 bits, the UE may use the configured PUSCH resources based on CG configuration #1. Otherwise, the UE may use the configured PUSCH resources based on CG configuration #2. In some embodiments, the CG configuration may be associated with a logical channel (or DRB) in the RRC_INACTIVE state. In some embodiments, if the size of all available CGs is less than the size of the small data to be transmitted, the UE may perform a RA procedure for small data transmission. In some embodiments, if the size of all available CGs is smaller than the size of the small data to be transmitted, the UE may perform an RRC recovery procedure. In some embodiments, if the small data for transmission (e.g., UL data in the buffer of allowed DRBs) is less than or equal to a data amount threshold (e.g., a size limit of the CG configured by the BS), the UE may use a CG for small data transmission.

[0056] In some embodiments, a UE (e.g., in RRC_INACTIVE state or in RRC_CONNECTED state) may receive an RRC release message with a suspension configuration to indicate allowed logical channels or DRBs in RRC_INACTIVE state. That is, only UL data associated with the allowed logical channels or DRBs may be transmitted by the UE in RRC_INACTIVE state via pre-configured PUSCH resources. In some embodiments, if the UE receives an RRC release message including a suspension configuration and indicating allowed logical channels or DRBs to the UE, the UE in RRC_INACTIVE state may suspend all SRBs and DRBs except SRB 0 and allowed DRBs. The UE may instruct the lower layers to suspend the PDCP entity for all DRBs except allowed DRBs.

[0057] In some embodiments, a UE (e.g., in RRC_INACTIVE state or in RRC_CONNECTED state) may receive an RRC release message with a suspension configuration to indicate a disallowed logical channel or DRB in RRC_INACTIVE state. That is, UL data associated with the disallowed logical channel or DRB will not be transmitted by the UE in RRC_INACTIVE over the pre-configured PUSCH resources. In some embodiments, if a UE (e.g., in RRC_CONNECTED state or in RRC_INACTIVE state) receives an RRC release message including a suspension configuration and indicating a disallowed logical channel or DRB, the UE may suspend all SRBs and disallowed DRBs except SRB 0 and other DRBs. The UE may instruct the lower layers of the disallowed DRBs except other DRBs to suspend the PDCP entity.

[0058] In some embodiments, if a UE (e.g., a UE in RRC_INACTIVE or in RRC_CONNECTED) receives an RRC release message including a suspension configuration, and (RRC_INACTIVE is implicitly or explicitly indicated to allow small data transmission in the RRC_INACTIVE state), the UE in the RRC_INACTIVE state may suspend all SRBs and DRBs except SRB 0 and the default DRB. The UE may instruct the lower layers to suspend the PDCP entity for DRBs other than the default DRB. In some embodiments, if a pre-configured PUSCH resource is provided to the UE for small data transmission in the RRC_INACTIVE state, the UE may consider that small data transmission in the RRC_INACTIVE state is allowed (e.g., via the pre-configured PUSCH resource or via an RA procedure (e.g., a 2-step RA procedure, a 4-step RA procedure, a 2-step fallback to a 4-step RA procedure)). In some embodiments, if a UE is provided with preconfigured PUSCH resources for small data transmission in the RRC_INACTIVE state, the UE may consider that small data transmission in the RRC_INACTIVE state is allowed (e.g., via preconfigured PUSCH resources or via any available RA procedure). In some embodiments, if a UE is provided with preconfigured PUSCH resources for small data transmission in the RRC_INACTIVE state, the UE may consider that small data transmission via the preconfigured PUSCH resources is allowed in the RRC_INACTIVE state, but whether small data transmission via the RA procedure is allowed may follow an indication from the BS (e.g., via dedicated signaling or via system information as described above). In some embodiments, if no preconfigured PUSCH resources are provided to the UE for small data transmission in the RRC_INACTIVE state, the UE may consider that small data transmission in the RRC_INACTIVE state via the RA procedure (e.g., a 2-step RA procedure, a 4-step RA procedure, a 2-step fallback to a 4-step RA procedure) is allowed.

[0059] In some embodiments, if a UE receives an RRC release message including a suspension configuration (e.g., in RRC_CONNECTED state or in RRC_INACTIVE state) and indicates allowed logical channels or DRBs, the UE may not suspend all DRBs and may not instruct lower layers of all DRBs to suspend the PDCP entity.

[0060] In some embodiments, only UL data associated with allowed logical channels or DRBs can be transmitted via preconfigured PUSCH resources. For example, when the UE is in RRC inactive state and the UL data belongs to an allowed logical channel or DRB, the UE can use the preconfigured PUSCH resources for small data transmission. Note that if the preconfigured PUSCH resources (or associated RRC procedures) for small data transmission are used, the UE may not need to transition to the RRC_CONNECTED state. In some embodiments, only UL data associated with allowed logical channels or DRBs can trigger small data transmission on preconfigured PUSCH resources. If there is other UL data that is not associated with the allowed logical channel or DRB, and if there is still available space on the (same) preconfigured PUSCH resources, the UE can also transmit other UL data that is not associated with the allowed logical channel or DRB on the same preconfigured PUSCH resources for small data transmission. Note that data accommodation for other UL data not associated with allowed logical channels or DRBs on the same preconfigured PUSCH resources (or remaining space on the same preconfigured PUSCH resources) may rely on the logical channel priority mechanism.

[0061] In some embodiments, if there is UL data that is not associated with an allowed logical channel or DRB when the UE is in the RRC_INACTIVE state, the UE may need to transmit an RRC resume request message to the BS. The UE in the RRC_INACTIVE state may receive an RRC resume message or an RRC setup command transmitted by the BS and transition to the RRC_CONNECTED state for small data transmission.

[0062] In some implementations, the BS may indicate to the UE in the RRC_INACTIVE state whether to allow small data transmission using pre-configured PUSCH resources through dedicated signaling (eg, an RRC release message with a suspension configuration).

[0063] In some embodiments, the UE may determine whether the CG (e.g., pre-configured PUSCH resources) for small data transmission is valid. In one example, if a UE in the RRC_INACTIVE state does not have a valid timing advance (TA), the UE may not be allowed to transmit small data via pre-configured PUSCH resources. That is, when the UE does not have a valid TA associated with the CG, the UE determines that the CG is invalid. In another example, when a UE in the RRC_INACTIVE state receives system information from a cell other than the last serving cell, the UE in the RRC_INACTIVE state is not allowed to transmit small data via pre-configured PUSCH resources. The last serving cell may be a cell that transmits an RRC release message including a suspension configuration to the UE. In other words, when the UE resides on a cell from which the UE receives an RRC release message, the UE may determine that the CG is valid. In one example, the last serving cell may be a cell that requests the UE to transition from the RRC_CONNECTED state to the RRC_INACITVE state through dedicated signaling (e.g., an RRC release message including a suspension configuration). In another example, the last serving cell may be a cell that requests a UE in RRC_INACTIVE state to remain in RRC_INACTIVE state via dedicated signaling (e.g., an RRC release message including a suspension configuration). In some embodiments, when a UE in RRC_INACTIVE state moves out of a configured RNA or when a periodic RNA timer (e.g., T380) expires, the UE in RRC_INACTIVE state is not allowed to transmit small data via pre-configured PUSCH resources. The UE in RRC_INACTIVE state may be configured with RNA by the last serving cell via an RRC release message including a suspension configuration. In some embodiments, the BS may provide pre-configured PUSCH resources (e.g., CG type 1 configuration) in dedicated signaling (e.g., in an RRC release message with a suspension configuration) and may also provide a life timer (e.g., TA timer) for the pre-configured PUSCH resources. For example, CG configuration #1 (for providing PUSCH resources when the UE is in RRC_INACTIVE state) may be associated with a life timer (e.g., TA timer). In some embodiments, the UE may start a life timer (e.g., a TA timer) for a CG after receiving an RRC release message with a pause configuration. In one example, a common life timer (e.g., a common TA timer) for one or more CGs may be provided to the UE. In another example, different life timers (e.g., different TA timers) may be provided for different CGs. In other examples, a life timer (e.g., a TA timer) may be configured for all preconfigured PUSCH resources.Note that while a life timer (e.g., TA timer) is running, the associated preconfigured PUSCH resources may be considered valid. Once a life timer (e.g., TA timer) expires (or is not running), the UE may consider all preconfigured PUSCH resources invalid. That is, the UE is not allowed to use preconfigured PUSCH resources for small data transmission in the RRC_INACTIVE state. In some embodiments, the TA value of the TA timer applied to the UE in the RRC_INACTIVE state may be provided in dedicated signaling (e.g., in an RRC release message with a pause configuration). In some embodiments, if the TA value applied to the UE in the RRC_INACTIVE state is not provided in the dedicated signaling, the UE may continue to use the current TA value when the UE enters the RRC_INACTIVE state. Note that the current TA value may be the most recently applied TA value for UL transmission, or the TA value in the most recently received TA command from the BS, but is not limited thereto. In some embodiments, the UE may be configured with an (absolute) threshold to determine whether the current TA (or associated CG) is valid. For example, a reference signal received power (RSRP) threshold may be configured (via dedicated signaling or broadcast system information) to determine whether the current TA (or associated CG) is valid. In this case, if the RSRP of the downlink path loss reference (or the RSRP of the downlink reference signal) is higher than the threshold, the TA (or associated CG) may be considered valid and the UE may use preconfigured PUSCH resources for small data transmission (e.g., PUSCH resources associated with the downlink reference signal of the synchronization signal block (SSB)). For example, if one or more SSBs are configured with preconfigured PUSCH resources and one or more SSBs with corresponding RSRP is greater than a threshold, the UE may randomly select an SSB with corresponding RSRP greater than the threshold and transmit UL data via the preconfigured PUSCH resources associated with the SSB for small data transmission in the RRC_INACTIVE state. Note that the above-mentioned threshold (e.g., RSRP) for determining whether the CG is valid may be replaced by reference signal received quality (RSRQ), received signal strength indication (RSSI), or other signal strength measurements for embodiments of the present disclosure. In some embodiments, the UE may be configured with a range to determine whether the current TA (or associated CG) is valid. For example, the RSRP range may be configured (via dedicated signaling or broadcast system information) to determine whether the current TA (or associated CG) is valid.In this case, if the RSRP of the downlink path loss reference (or the RSRP of the downlink reference signal) is within the range, the TA (or the associated CG) can be considered valid and the UE can use the preconfigured PUSCH resources (e.g., PUSCH resources associated with the downlink reference signal of the SSB) for small data transmission. In some embodiments, the UE in the RRC_INACTIVE state can measure the downlink reference signal (e.g., SSB, channel state information reference signal (CSI-RS)) from the cell. Based on the measurement results (e.g., the RSRP of the downlink reference signal), the UE can determine whether the preconfigured PUSCH resources (e.g., PUSCH resources associated with the SSB or CSI-RS) are valid for small data transmission in the RRC_INACTIVE state.

[0064] In some embodiments, a UE (e.g., in an RRC_CONNECTED state or in an RRC_INACTIVE state) may be configured with pre-configured PUSCH resources for a cell for small data transmission in the RRC_INACTIVE state. For example, the cell may be identified by the cell identifier and / or physical cell identifier of the source PCell (e.g., the last serving cell) stored in the UE inactive AS context. In one example, when the UE resides on a cell and the UE receives an RRC release message for a CG from the cell, the UE may consider the CG (e.g., the pre-configured PUSCH resources) to be a valid CG. On the other hand, if the UE leaves / moves out of the coverage of the cell (e.g., the source PCell), or if the UE is not residing on the cell (e.g., the source PCell), or if the UE is not served by the cell (e.g., the source PCell), the pre-configured PUSCH resources associated with the cell may be considered invalid. In one example, if the UE leaves the coverage of a cell (e.g., a source PCell), or if the UE is not resident on a cell (e.g., a source PCell), or if the UE is not served by the cell (e.g., a source PCell), the pre-configured PUSCH resources associated with the cell may be considered invalid, but the corresponding CG type 1 configuration may be retained by the UE. For example, if the UE moves back to the original serving cell, the CG may still be used for small data transmission if it is still valid (e.g., the CG is considered valid based on a TA timer or an RSRP threshold). In another example, if the UE leaves the coverage of a cell (e.g., a source PCell), or if the UE is not resident on a cell (e.g., a source PCell), or if the UE is not served by the cell (e.g., a source PCell), the pre-configured PUSCH resources associated with the cell may be considered invalid, but the corresponding CG type 1 configuration may be removed by the UE. In some embodiments, a UE in an RRC_CONNECTED state or an RRC_INACTIVE state may be configured with pre-configured PUSCH resources of a group of cells for small data transmission in the RRC_INACTIVE state. For example, the group of cells may be cells belonging to a configured RNA (or as part thereof). For example, the group of cells may be configured together with a corresponding CG type 1 configuration. In some embodiments, a cell may broadcast a common TA value for small data transmission (e.g., via SIB1) for a UE in an RRC_INACTIVE state. A UE in an RRC_IDLE state or an RRC_INACTIVE state may receive a broadcast common TA value for small data transmission. A UE in an RRC_INACTIVE state may apply a broadcast common TA value to small data transmission.In some implementations, if a UE in RRC_INACTIVE state does not receive a TA value from the cell (through dedicated signaling or broadcast system information), the UE may not be allowed to use pre-configured PUSCH resources for small data transmission in RRC_INACTIVE state.

[0065] Note that the UE may perform small data transmission via the CG if at least one of the following criteria or conditions is met: (1) the size of the small data (e.g., the amount of UL data belonging to the allowed DRB to be transmitted in the buffer) is less than or equal to the data amount threshold; (2) the CG is valid; (3) the UE has a valid TA, for example, if the UE is configured with a CG for small data transmission in the RRC_INACTIVE state and / or is allowed to transmit small data via the CG in the RRC_INACTIVE state, the UE may check whether at least one of the above criteria is met or complies. Note that the amount of UL data belonging to the allowed DRB may be calculated based on the associated RLC buffer and the associated PDCP buffer of the allowed DRB.

[0066] In some embodiments, if the UE remains stationary after receiving an RRC release message with a pause configuration, the UE may be allowed to use pre-configured PUSCH resources for small data transmission. In one example, when the UE is in the RRC_CONNECTED state or the RRC_INACTIVE state, the UE may report to the BS that its mobility state is stationary. Therefore (or in response to the reported mobility state being stationary), the BS may provide pre-configured PUSCH resources to the UE in the RRC_INACTIVE state or in the RRC_CONNECTED state to transmit small data in the RRC_INACTIVE state. In another example, if the UE was stationary before reporting its mobility state (e.g., when the UE was in the RRC_CONNECTED state), but the mobility state changed (e.g., when the UE was in the RRC_INACTIVE state), the UE in the RRC_INACTIVE state is not allowed to use pre-configured PUSCH resources for small data transmission in the RRC_INACTIVE state. In another example, if the UE changes its mobility state while in the RRC_INACTIVE state, the UE needs to report the new mobility state to the BS (e.g., by transitioning to the RRC_CONNECTED state and reporting the updated mobility state to the BS, by transmitting an RRC RESUME REQUEST message including the new mobility state). Note that after reporting the updated mobility state to the BS, the UE may remain in the RRC state that was in when the UE reported the mobility state, or may remain in the RRC_CONNECTED state, depending on an indication from the BS (e.g., through dedicated signaling).

[0067] In some embodiments, when a UE transmits UL data (e.g., small data) via a preconfigured PUSCH resource, the UE may monitor (via dedicated signaling or broadcast system information) the preconfigured PDCCH or CORESET to receive acknowledgment (ACK) information (e.g., by monitoring the initial CORESET or CORESET#0 using a C-RNTI, recovery ID, or other RNTI). If the UE does not receive ACK information associated with the small data transmission, the UE may retransmit the small data. In one example, when the UE does not receive ACK information "N" times in the RRC_INACTIVE state, the UE may consider the preconfigured PUSCH resource invalid. In one example, "N" may be configured or predefined by the BS (via dedicated signaling or broadcast system information). In one example, the ACK information for small data transmission may also carry a new TA value to be applied to the small data transmission in the RRC_INACTIVE state.

[0068] In some embodiments, the cell may broadcast an indication to indicate whether the CG (e.g., pre-configured PUCCH resources) for small data transmission in the RRC_INACTIVE state is allowed. Thus, if the indication indicating that small data transmission via the CG in the RRC_INACTIVE state is allowed, the UE receives an indication to perform small data transmission via the CG in the RRC_INACTIVE state.

[0069] When CG for small data transmission is configured, fall back to RA process for small data transmission

[0070] In some embodiments, if a UE in an RRC_INACTIVE state is configured with PUSCH resources for small data transmission and also allows small data transmission via an RA process, the UE may first use the preconfigured PUSCH resources for small data transmission. In one example, if a UE in an RRC_INACTIVE state is configured with PUSCH resources for small data transmission and also allows small data transmission via an RA process, the UE may use the resources configured first (e.g., PUSCH resources of MSGA or preconfigured PUSCH resources). In another example, if a UE in an RRC_INACTIVE state is configured with PUSCH resources for small data transmission and also allows small data transmission via an RA process, the UE may use resources that can accommodate small data (e.g., PUSCH resources of MSGA or preconfigured PUSCH resources) (as much as possible). In other examples, if a UE in an RRC_INACTIVE state is configured with PUSCH resources for small data transmission and also allows small data transmission via an RA process, small data transmission via preconfigured PUSCH resources and via an RA process may not be performed simultaneously.

[0071] In some embodiments, if a UE in the RRC_INACTIVE state is configured with PUSCH resources for small data transmission, but the pre-configured PUSCH resources are deemed invalid (or do not meet the above-mentioned conditions for small data transmission via PUSCH resources), the UE may fall back to transmitting small data via an RA procedure (e.g., a 2-step RA procedure, a 4-step RA procedure, or a 2-step RA procedure falling back to a 4-step RA procedure). Note that the pre-configured PUSCH resources for small data transmission may be deemed invalid because a life timer (e.g., a TA timer) expires, the UE leaves the coverage of the source PCell identified as stored in the UE inactive AS context (e.g., the UE and the source PCell may retain the UE inactive AS context), or the UE does not receive ACK information within "N" times. In some embodiments, the BS may indicate whether a fallback mechanism for small data transmission in the RRC_INACTIVE state is applied. For example, the BS may indicate that a fallback mechanism for invalid PUSCH resources (or a fallback mechanism when the conditions for small data transmission via PUSCH resources are not met) is not applied. In this case, if the UE in the RRC_INACTIVE state is configured with PUSCH resources for small data transmission, but the pre-configured PUSCH resources are deemed invalid (or do not meet the conditions for small data transmission through PUSCH resources), the UE may transmit an RRC recovery request message to transition to the RRC_CONNECTED state for small data transmission. For example, the BS may indicate that a fallback mechanism with a 2-step RA process for invalid PUSCH resources is applied. In this case, if the UE in the RRC_INACTIVE state is configured with PUSCH resources for small data transmission, but the pre-configured PUSCH resources are deemed invalid, the UE may initiate a 2-step RA process in RRC_INACTIVE for small data transmission in the RRC_INACTIVE state. For example, the BS may indicate that a fallback mechanism with a 4-step RA process for invalid PUSCH resources is applied. In this case, if a UE in the RRC_INACTIVE state is configured with PUSCH resources for small data transmission, but the pre-configured PUSCH resources are considered invalid, the UE may initiate a 4-step RA procedure in RRC_INACTIVE for small data transmission in the RRC_INACTIVE state. For example, the BS may indicate that a fallback mechanism with an RA procedure for invalid PUSCH resources is applied.In this case, if the UE in the RRC_INACTIVE state is configured with PUSCH resources for small data transmission, but the pre-configured PUSCH resources are considered invalid, the UE can initiate a 2-step RA process or a 4-step RA process based on the configuration threshold for the 2-step RA process selection, RRC_INACTIVE, for small data transmission in the RRC_INACTIVE state. That is, the UE can select the type of random access (e.g., 2-step RA process or 4-step RA process) based on the network configuration. For example, the UE can use the RSRP threshold to select between 2-step CBRA and 4-step CBRA at the start of the RA process.

[0072] In some embodiments, if the fallback mechanism with the RA procedure fails, the UE may bar the cell on which the RA procedure is performed and perform cell reselection. The cell may be barred within a configurable or predefined period (e.g., 300 seconds). In some embodiments, if the fallback mechanism with the RA procedure fails, the UE is prohibited from transmitting small data in the RRC_INACTIVE state within a configurable or predefined period. In some embodiments, if the fallback mechanism with the RA procedure fails, the UE is prohibited from transmitting small data in the RRC_INACTIVE state, and an RRC recovery procedure may be performed to transition to the RRC_CONNECTED state. For example, the UE may transition to the RRC_CONNECTED state after receiving an RRC recovery message from the BS. For example, after receiving an RRC release message with a suspend configuration from the BS, the UE may remain in the RRC_INACTIVE state.

[0073] In some embodiments, the UE may report to the BS that the preconfigured PUSCH resources for small data transmission have become invalid in the RRC_INACTIVE state. In some embodiments, the UE may report to the BS that the small data transmission via the RA procedure in the RRC_INACTIVE state has failed. In some embodiments, the UE may report to the BS that the small data transmission via the 2-step RA procedure in the RRC_INACTIVE state has failed. In some embodiments, the UE may report to the BS that the small data transmission via the 4-step RA procedure in the RRC_INACTIVE state has failed.

[0074] Figure 1 FIG. 1 is a flow chart of a rollback method 100 according to an embodiment of the present disclosure. Figure 1As shown, when a CG (e.g., a preconfigured PUSCH resource) is configured for small data transmission, but at least one of the predefined conditions (e.g., (1) the size of the small data is less than or equal to the data amount threshold; (2) the CG is valid; (3) the UE has a valid TA) for small data transmission via the CG is not confirmed / satisfied / achieved. In action 102, the UE receives an indication from the BS indicating that small data transmission is allowed via a RA procedure (e.g., a 2-step RA procedure or a 4-step RA procedure) in the RRC_INACTIVE state. In action 104, the UE receives a CG for small data transmission from the BS. Optionally, the UE may receive an indication indicating that small data transmission is allowed through the CG in the RRC_INACTIVE state in action 104. In action 106, the UE determines whether the size of the small data is less than or equal to the data amount threshold, whether the CG is valid for small data transmission (e.g., based on the TA timer or RSRP threshold as described above), and whether the UE has a valid TA. Note that actions 102 and 104 may be optional. In action 108, when the UE determines that the size of the small data is less than or equal to the data amount threshold, the CG is valid, and the UE has a valid TA, the UE performs small data transmission on the CG. In action 110, when the UE determines that the size of the small data is greater than the data amount threshold, the CG is not valid or invalid, and the UE does not have a valid TA, the UE performs small data transmission via the RA procedure.

[0075] UE capability to support small data transmission

[0076] In some embodiments, the UE may report its ability to support small data transmission in the RRC_INACTIVE state. In some embodiments, the UE may report its ability to support small data transmission through the RA procedure in the RRC_INACTIVE state. In some embodiments, the UE may report its ability to support small data transmission through the 2-step RA procedure in the RRC_INACTIVE state. In some embodiments, the UE may report its ability to support small data transmission through the 4-step RA procedure in the RRC_INACTIVE state. In some embodiments, the UE may report its ability to support small data transmission through the 2-step RA procedure and fall back to the 4-step RA procedure in the RRC_INACTIVE state. In some embodiments, the UE may report its ability to support small data transmission through the pre-configured PUSCH resources in the RRC_INACTIVE state. In some embodiments, a UE that supports small data transmission in the RRC_INACTIVE state may be forced to support small data transmission via the RA procedure and may optionally support small data transmission via pre-configured PUSCH resources (for example, the UE may need to signal its ability to support small data transmission via pre-configured PUSCH resources in the RRC_INACTIVE state). In some embodiments, a UE supporting small data transmission in the RRC_INACTIVE state may be forced to support small data transmission via a 4-step RA procedure, optionally support small data transmission via a 2-step RA procedure (e.g., the UE needs to signal its ability to support small data transmission via a 2-step RA procedure in the RRC_INACTIVE state), and optionally support small data transmission via pre-configured PUSCH resources (e.g., the UE needs to signal its ability to support small data transmission via a pre-configured PUSCH resource in the RRC_INACTIVE state). In some embodiments, a UE supporting small data transmission in the RRC_INACTIVE state may be forced to support small data transmission via a pre-configured PUSCH resource, optionally support small data transmission via a 2-step RA procedure (e.g., the UE may need to signal its ability to support small data transmission via a 2-step RA procedure in the RRC_INACTIVE state), and optionally support small data transmission via a 4-step RA procedure (e.g., the UE needs to signal its ability to support small data transmission via a 4-step RA procedure in the RRC_INACTIVE state). In some embodiments, a UE supporting small data transmission in the RRC_INACTIVE state may be forced to support small data transmission via pre-configured PUSCH resources, and optionally support small data transmission via the RA process (e.g., the UE needs to signal in the RRC_INACTIVE state the ability to support small data transmission via the RA process).

[0077] In some embodiments, the UE may report its capability to support small data transmission on the SUL in the RRC_INACTIVE state.

[0078] In some embodiments, UE capabilities may be separated in frequency range 1 (FR1) and frequency range 2 (FR2). For example, a UE may report its capability of supporting small data transmission in RRC_INACTIVE state in FR1 and another capability of supporting small data transmission in RRC_INACTIVE state in FR2.

[0079] In some embodiments, the UE capabilities may be separated in time division duplex (TDD) mode and frequency division duplex (FDD) mode. For example, the UE may report its ability to support small data transmission in the RRC_INACTIVE state in TDD mode and another capability to support small data transmission in the RRC_INACTIVE state in FDD mode.

[0080] Note that the above embodiment is also applicable to other RRC states (eg, RRC_IDLE state).

[0081] Note that after transmitting the UE capability for supporting small data transmission in the RRC_INACTIVE state to the BS, the BS can provide the CG (e.g., preconfigured PUSCH resources) in the RRC release message. Therefore, when the predefined conditions are confirmed / satisfied / met, the UE in the RRC_INACTIVE state performs small data transmission through the CG.

[0082] Figure 22 is a flowchart of a method 200 for small data transmission according to an embodiment of the present disclosure. In action 202, the UE determines whether a CG for small data transmission in the RRC_INACTIVE state is received. Optionally, the UE may receive an indication indicating that small data transmission through the RRC_INACTIVE CG in the RRC_INACTIVE state is allowed in action 202. In one example, the configuration of the CG is included in the RRC release message. Note that the RRC release message may include at least one of the configuration of the TA timer associated with the CG and the configuration of the DRB for allowing small data transmission in the RRC_INACTIVE state. In action 204, the UE determines whether the size of the small data is less than or equal to the data amount threshold, whether the CG is valid for small data transmission, and whether the UE has a valid TA when the UE receives the CG for small data transmission. In action 206, when the UE determines that the CG is valid for small data transmission, the size of the small data is less than or equal to the data amount threshold, and the UE has a valid TA, the UE transmits the small data corresponding to the allowed DRB through the CG. Note that, as described above, the UE can determine whether the CG is valid for small data transmission based on the TA timer or the RSRP threshold. On the other hand, when the UE does not receive a CG for small data transmission, or when the CG is invalid for small data transmission, the size of the small data is greater than the data amount threshold, or the UE does not have a valid TA, the UE can transmit the small data corresponding to the allowed DRB through the RA process (e.g., the above-mentioned fallback method) (e.g., action 208).

[0083] Figure 3 A block diagram of a node 300 for wireless communication according to one aspect of the present disclosure is shown.

[0084] like Figure 3 As shown, the node 300 may include a transceiver 320, a processor 326, a memory 328, one or more presentation components 334, and at least one antenna 336. The node 300 may also include a radio frequency (RF) spectrum band module, a BS communication module, a network communication module, and a system communication management module, input / output (I / O) ports, I / O components, and a power supply ( Figure 3 Each of these components may communicate with each other directly or indirectly via one or more buses 340. In one embodiment, the node 300 may be a UE or a BS, which performs, for example, Figure 2 Various functions are described here.

[0085] The transceiver 320 has a transmitter 322 (e.g., transmitting / transmission circuitry) and a receiver 324 (e.g., receiving / reception circuitry) and can be configured to transmit and / or receive time and / or frequency resource partitioning information. In one embodiment, the transceiver 320 can be configured to transmit in different types of subframes and time slots, including but not limited to usable, unusable, and flexibly usable subframe and time slot formats. The transceiver 320 can be configured to receive data and control channels.

[0086] Node 300 may include a variety of computer-readable media. Computer-readable media can be any available media that can be accessed by node 300, and includes both volatile (and non-volatile) media and removable (and non-removable) media. Computer-readable media include computer storage media and communication media. Computer storage media may include volatile (and / or non-volatile) media and removable (and / or non-removable) media implemented according to any method or technology for storing information such as computer-readable instructions, data structures, program modules, or data.

[0087] Computer storage media may include RAM, ROM, EEPROM, flash memory (or other storage technology), CD-ROM, Digital Versatile Disk (DVD) (or other optical disk storage), magnetic tape, magnetic disk storage (or other magnetic storage devices), etc. Computer storage media may not include propagated data signals. Communication media generally can contain computer readable instructions, data structures, program modules or other data in a modulated data signal such as a carrier wave or other transport mechanism, and include any information delivery media. The term "modulated data signal" refers to a signal having one or more characteristics that are set or changed so as to encode information in the signal. Communication media can include wired media, such as a wired network or direct wired connection, and wireless media, such as acoustic, RF, infrared and other wireless media. Any combination of the above should also be included within the scope of computer readable media.

[0088] The memory 328 may include computer storage media in the form of volatile and / or non-volatile memory. The memory 328 may be removable, non-removable, or a combination thereof. For example, the memory 328 may include solid-state memory, a hard drive, an optical drive, etc. Figure 3As shown, the memory 328 may store computer-readable and / or computer-executable instructions 332 (e.g., software code) that, when executed, are configured to cause the processor 326 to perform the various functions described herein. Alternatively, the instructions 332 may not be directly executed by the processor 326, but may be configured to cause the node 300 (e.g., when compiled and executed) to perform the various functions described herein.

[0089] Processor 326 may include an intelligent hardware device, a central processing unit (CPU), a microcontroller, an ASIC, etc. Processor 326 may include a memory. Processor 326 may process data 330 and instructions 332 received from memory 328, as well as information passed through transceiver 320, a baseband communication module, and / or a network communication module. Processor 326 may also process information to be sent to transceiver 320 for transmission to the network communication module via antenna 336 for transmission to the CN.

[0090] One or more presentation components 334 can present the data indication to a person or other device. Examples of presentation components 334 can include a display device, a speaker, a printing component, a vibration component, and the like.

[0091] As can be seen from this disclosure, various techniques can be used to implement the concepts described in this application without departing from the scope of these concepts. In addition, although these concepts have been described with specific reference to certain implementations, those of ordinary skill in the art will recognize that changes can be made in form and detail without departing from the scope of these concepts. Therefore, the described implementations will be considered in all respects as illustrative and not restrictive. It should also be understood that this disclosure is not limited to the specific embodiments described above, but many rearrangements, modifications, and substitutions are possible without departing from the scope of this disclosure.

Claims

1. A method for transmitting small data for a user equipment (UE), the method comprising: receiving a radio resource control (RRC) release message from a base station (BS), the RRC release message including a configured authorized CG configuration and a first timer associated with the CG configuration, the CG configuration indicating uplink (UL) resources; In response to receiving the RRC release message, transitioning from the RRC_CONNECTED state to the RRC_INACTIVE state; In response to receiving the RRC release message, starting the first timer; Determine whether the UL resource is valid, the UL resource is invalid at least when the first timer expires; and After the UE determines that the UL resource is valid, UL data is transmitted on the UL resource.

2. The method according to claim 1, characterized in that The UL resources are also judged to be invalid when the serving cell of the UE is different from a primary cell supported by the BS and from which the UE receives the RRC release message.

3. The method according to claim 1, characterized in that When the reference signal received power RSRP of the synchronization signal block SSB associated with the UL resource is not greater than a threshold, the UL resource is also judged to be invalid.

4. The method according to claim 1, wherein The RRC release message also indicates one or more data radio bearers (DRBs) that are allowed to perform UL data transmission in the RRC_INACTIVE state.

5. The method according to claim 1, characterized in that The UL resources are also judged to be invalid when the size of the UL data to be transmitted is greater than a threshold associated with the CG configuration.

6. The method according to claim 1, further comprising: Report to the BS the ability to support performing the small data transmission through the CG configuration in the RRC_INACTIVE state.

7. The method according to claim 1, further comprising: and reporting to the BS a capability of supporting the small data transmission through a random access (RA) procedure in the RRC_INACTIVE state.

8. The method according to claim 7, further comprising: When the UE determines that the UL resource is invalid, it determines whether to perform the RA process for the small data transmission.

9. The method according to claim 7, further comprising: An indication is received from the BS through system information, the indication indicating whether the RA procedure for the small data transmission is allowed.

10. The method according to claim 1, characterized in that The UL resources include physical uplink shared channel PUSCH resources.

11. A user equipment (UE) for performing small data transmission, the UE comprising: at least one processor; and At least one memory coupled to the at least one processor, the at least one memory storing computer-executable instructions that, when executed by the at least one processor, cause the UE to: receiving a radio resource control (RRC) release message from a base station (BS), the RRC release message including a configured authorized CG configuration and a first timer associated with the CG configuration, the CG configuration indicating uplink (UL) resources; In response to receiving the RRC release message, transitioning from the RRC_CONNECTED state to the RRC_INACTIVE state; In response to receiving the RRC release message, starting the first timer; Determine whether the UL resource is valid, the UL resource is invalid at least when the first timer expires; and After the UE determines that the UL resource is valid, UL data is transmitted on the UL resource.

12. The UE according to claim 11, wherein: The UL resources are also judged to be invalid when the serving cell of the UE is different from a primary cell supported by the BS and from which the UE receives the RRC release message.

13. The UE according to claim 11, wherein: When the reference signal received power RSRP of the synchronization signal block SSB associated with the UL resource is not greater than a threshold, the UL resource is also judged to be invalid.

14. The UE according to claim 11, wherein: The RRC release message also indicates one or more data radio bearers (DRBs) that are allowed to perform UL data transmission in the RRC_INACTIVE state.

15. The UE according to claim 11, wherein: The UL resources are also judged to be invalid when the size of the UL data to be transmitted is greater than a threshold associated with the CG configuration.

16. The UE according to claim 11, wherein: When the computer-executable instructions are executed by the at least one processor, the UE is further caused to: Report to the BS the ability to support performing the small data transmission through the CG configuration in the RRC_INACTIVE state.

17. The UE according to claim 11, wherein: When the computer-executable instructions are executed by the at least one processor, the UE is further caused to: and reporting to the BS a capability of supporting the small data transmission through a random access (RA) procedure in the RRC_INACTIVE state.

18. The UE according to claim 17, wherein: When the computer-executable instructions are executed by the at least one processor, the UE is further caused to: When the UE determines that the UL resource is invalid, it determines whether to perform the RA process for the small data transmission.

19. The UE according to claim 17, wherein: When the computer-executable instructions are executed by the at least one processor, the UE is further caused to: An indication is received from the BS through system information, the indication indicating whether the RA procedure for the small data transmission is allowed.

20. The UE according to claim 11, wherein: The UL resources include physical uplink shared channel PUSCH resources.

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