Method and user equipment for small data transmission

Abstract

A method for small data transmission and a user equipment (UE) are provided. The method includes: receiving from a base station (BS) an indication of the configuration of dedicated physical resources; performing the small data transmission based on the dedicated physical resources; and receiving from the BS an acknowledgment (ACK) indicator indicating that the BS has successfully received the small data transmission, wherein the UE is in a deactivated state when performing the small data transmission.

Description

[0001] Cross-reference to related applications

[0002] This application is a national phase application pursuant to International Patent Application No. PCT / CN2020 / 136734, filed December 16, 2020, under 35 U.S.SC §371, which claims the benefit and priority of Provisional U.S. Patent Application Serial No. 62 / 955,741, filed December 31, 2019. For all purposes, the contents of all the foregoing applications are hereby incorporated herein by reference in their entirety. Technical Field

[0003] This disclosure relates generally to wireless communications, and more specifically to methods and user equipment for small data transmission. Background Technology

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

[0005] 5G NR systems are designed to provide flexibility and configurability to optimize NW services and types to adapt to different use cases, such as enhanced mobile broadband (eMBB), massive machine-type communication (mMTC), and ultra-reliable and low-latency communication (URLLC).

[0006] However, with the continued increase in demand for radio access, there is a need in the field to improve small data transmission. Summary of the Invention

[0007] This disclosure relates to a method and a user equipment (UE) for small data transmission when the UE is in a deactivated state.

[0008] According to one aspect of this disclosure, a method for small data transmission performed by a user equipment (UE) is provided. The method includes: receiving from a base station (BS) an indication of the configuration of dedicated physical resources; performing the small data transmission based on the dedicated physical resources; and receiving from the BS an acknowledgment (ACK) indicator indicating that the BS has successfully received the small data transmission, wherein the UE is in a deactivated state when performing the small data transmission.

[0009] According to one aspect of this disclosure, a user equipment (UE) is provided in a wireless communication system for small data transmission, the wireless communication system including a base station (BS). The UE includes: a processor; and a memory coupled to the processor, wherein the memory stores a computer-executable program that, when executed by the processor, causes the processor to: perform the small data transmission based on dedicated physical resources; and receive from the BS an acknowledgment (ACK) indicator indicating that the BS has successfully received the small data transmission, wherein the UE is in a deactivated state when performing the small data transmission. Attached Figure Description

[0010] When combined with attachment Figure 1 When reading this document, the following points will best help you understand aspects of this disclosure. The various features are not drawn to scale. For clarity of discussion, the sizes of the various features may be arbitrarily increased or decreased.

[0011] Figure 1 A 2-step RACH process, which is formed by a 4-step RACH process, is shown according to an exemplary embodiment of the present disclosure.

[0012] Figure 2 A fallback RAR format according to an exemplary embodiment of this disclosure is shown.

[0013] Figure 3 A successful RAR format according to an exemplary implementation of this disclosure is shown.

[0014] Figure 4 A successful RAR MAC subheader format according to an exemplary implementation of this disclosure is shown.

[0015] Figure 5 A novel RAR format according to an exemplary implementation of this disclosure is shown.

[0016] Figure 6 A modified successRAR format according to an exemplary embodiment of this disclosure is shown.

[0017] Figure 7 A small data transmission process performed by a UE according to an exemplary embodiment of this disclosure is illustrated.

[0018] Figure 8 A block diagram of a node for wireless communication according to an exemplary embodiment of the present disclosure is shown. Detailed Implementation

[0019] The following contains specific information relating to exemplary embodiments of the present disclosure. The accompanying drawings and detailed descriptions in this disclosure are only illustrative of exemplary embodiments. However, this disclosure is not limited to these exemplary embodiments. Other variations and embodiments of this disclosure will occur to those skilled in the art. Unless otherwise stated, the same or corresponding elements in the drawings may be indicated by the same or corresponding reference numerals. Furthermore, the figures and illustrations in this disclosure are generally not drawn to scale and are not intended to correspond to actual relative dimensions.

[0020] The following description contains specific information relating to exemplary embodiments in this disclosure. The accompanying drawings and detailed description are for illustrative purposes only. However, this disclosure is not limited to these exemplary embodiments. Other variations and embodiments of this disclosure will occur to those skilled in the art. Unless otherwise stated, the same or corresponding elements in the drawings may be indicated by the same or corresponding reference numerals. Furthermore, the figures and illustrations in this disclosure are generally not drawn to scale and are not intended to correspond to actual relative dimensions.

[0021] For the purposes of consistency and ease of understanding, similar features are identified by reference numerals in the exemplary drawings (but are not shown in some examples). However, features in different embodiments may differ in other respects and should therefore not be narrowly limited to what is shown in the drawings.

[0022] The use of terms such as “one embodiment,” “an embodiment,” “an exemplary embodiment,” “various embodiments,” “some embodiments,” or “embodiments of this disclosure” indicates that an embodiment of this disclosure described herein may include a particular feature, structure, or characteristic, but not every possible embodiment of this disclosure necessarily includes that particular feature, structure, or characteristic. Furthermore, the repeated use of the phrases “in one embodiment,” “in an exemplary embodiment,” or “an embodiment” does not necessarily refer to the same embodiment, although they may refer to the same embodiment. Additionally, any phrase used in conjunction with “this disclosure,” such as “embodiment,” is not intended to imply that all embodiments of this disclosure must include a particular feature, structure, or characteristic, but should be understood to mean that “at least some embodiments of this disclosure” include the stated particular feature, structure, or characteristic. The term “coupled” is defined as a connection, whether direct or indirect through intermediate components, and is not necessarily limited to a physical connection. The term “comprising” as used means “including but not limited to”; it specifically indicates open inclusion or membership in the combinations, groups, series, and equivalents described herein.

[0023] The term "and / or" in this document describes the relationship between related objects only, indicating that there may be three relationships. For example, "A and / or B" can mean: A exists alone, A and B exist simultaneously, or B exists alone. "A and / or B and / or C" can mean that at least one of A, B, and C exists. Furthermore, the character " / " used here generally indicates that the preceding and following related objects are in an "or" relationship.

[0024] Furthermore, for the purpose of non-limiting interpretation, specific details such as functional entities, technologies, protocols, and standards are described to provide an understanding of the described technologies. In other examples, detailed descriptions of well-known methods, technologies, systems, architectures, etc., are omitted to avoid unnecessary detail that could obscure this disclosure.

[0025] Those skilled in the art will readily recognize that any NW function or algorithm of this disclosure can be implemented by hardware, software, or a combination of software and hardware. The described functions may correspond to modules, which can be software, hardware, firmware, or any combination thereof. Software implementations may include computer-executable instructions stored on a computer-readable medium such as memory or other types of storage devices. For example, one or more microprocessors or general-purpose computers with communication processing capabilities may be programmed using the corresponding executable instructions to execute the described NW function or algorithm. These microprocessors or general-purpose computers may be formed using application-specific integrated circuits (ASICs), programmable logic arrays, and / or using one or more digital signal processors (DSPs). While several exemplary embodiments described in this disclosure are directed to software installed and executed on computer hardware, alternative exemplary embodiments implemented as firmware or hardware or a combination of hardware and software are also within the scope of this disclosure.

[0026] 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, magnetic tape, disk storage, or any other equivalent medium capable of storing computer-readable instructions.

[0027] A radio communication NW architecture (e.g., Long Term Evolution (LTE) systems, LTE-Advanced (LTE-A) systems, LTE-Advanced Pro systems) typically includes at least one base station (BS), at least one user equipment (UE), and one or more optional NW elements providing connectivity to the NW. The UE communicates with the NW (e.g., Core NW (CN), Evolved Packet Core (EPC), Evolved Universal Terrestrial Radio Access Network (E-UTRAN), Next-Generation Core (NGC), or the Internet) through a Radio Access Network (RAN) established by the BS.

[0028] It should be noted that in this disclosure, the UE may include, but is not limited to, a mobile station, a mobile terminal or device, or a user communication radio terminal. For example, the UE may be a portable wireless device, including but not limited to a mobile phone, tablet computer, wearable device, sensor, or personal digital assistant (PDA) with wireless communication capabilities. The UE is configured to receive signals through an air interface and transmit signals to one or more cells in the RAN.

[0029] A BS may include, but is not limited to, Node B (NB) in a Universal Mobile Telecommunication System (UMTS), Evolved Node B (eNB) in LTE-A, Radio Network Controller (RNC) in UMTS, Base Station Controller (BSC) in a Global System for Mobile communication (GSM) / GSM EDGE Radio Access NW (GERAN), Next Generation-eNB (ng-eNB) in an E-UTRA BS connected to a 5GC, Next Generation Node B (gNB) in a 5G Access NW (5G-AN), and any other device capable of controlling radio communications and managing radio resources within the cell. A BS can connect to an NW via a radio interface to serve one or more UEs.

[0030] The BS can be configured to provide communication services according to at least one of the following radio access technologies (RATs): WiMAX (Worldwide Interoperability for Microwave Access), GSM (commonly referred to as 2G), GERAN, General Packet Radio Service (GPRS), UMTS (commonly referred to as 3G) under Wideband-Code Division Multiple Access (W-CDMA), High-Speed ​​Packet Access (HSPA), LTE, LTE-A, evolved LTE (eLTE), New Radio (NR, commonly referred to as 5G), and / or LTE-A Pro. However, the scope of this disclosure should not be limited to the previously disclosed protocols.

[0031] A Base Station (BS) is operable to provide radio coverage to a specific geographic area using multiple cells included in the RAN. The BS supports cell operation. Each cell is operable to provide service to at least one UE within its radio coverage area. More specifically, each cell (often referred to as the serving cell) provides service to one or more UEs within its radio coverage area (e.g., each cell schedules downlink (DL) and optional UL resources to at least one UE within its radio coverage area for downlink and optional uplink packet transmissions). The BS can communicate with one or more UEs in a radio communication system through multiple cells. Cells can allocate sidelink (SL) resources to support proximity service (ProSe). Each cell may have coverage areas overlapping with other cells. In the case of Multi-RAT Dual Connectivity (MR-DC), the master cell of a Master Cell Group (MCG) or Secondary Cell Group (SCG) can be referred to as a Special Cell (SpCell). The Primary Cell (PCell) can refer to the SpCell of the MCG. PSCell can refer to the SpCell of an SCG. MCG refers to the serving cell group associated with the master node (MN), including SpCells and optionally one or more secondary cells (SCells). SCG refers to the serving cell group associated with the secondary node (SN), including SpCells and optionally one or more Scells.

[0032] As previously disclosed, the frame structure for NR supports flexible configuration to accommodate 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. Orthogonal Frequency Division Multiplexing (OFDM) technology, as 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. Furthermore, two coding schemes are considered for NR: (1) Low Density Parity Check Code (LDPC) and (2) Polar Code. Coding scheme adaptation can be configured based on channel conditions and / or the service application.

[0033] Furthermore, it is considered that the transmission time interval of a single NR frame should include at least DL transmission data, protection period, and UL transmission data, wherein each part of the DL transmission data, protection period, and UL transmission data should also be configurable, for example, based on NR-based NW dynamics. Additionally, SL resources can also be provided in NR frames to support ProSe services.

[0034] In the following text, some descriptions are disclosed for certain terms presented in the following paragraphs:

[0035] Configured license type 1: It is semi-statically configured to operate upon receiving the Radio Resource Control (RRC) parameter configuredGrantConfig, which includes rrc-ConfiguredUplinkGrant, without detecting the UL license in the Downlink Control Information (DCI).

[0036] Cell: A radio network object that can be uniquely identified by a UE from a (cell) identifier broadcast from a UTRAN access point across a geographical area. A cell is a Frequency Division Duplex (FDD) cell.

[0037] Frequency Division Duplexing (FDD) or Time Division Duplexing (TDD) modes.

[0038] RACH procedure: The Random Access Channel (RACH) procedure is a series of processes between the UE and the gNB (network) to enable the UE to obtain UL synchronization and acquire a designated identifier (ID) for radio access communication.

[0039] PUSCH: Physical Uplink Shared Channel is the physical time / frequency resource that the gNB schedules to the UE for data transmission.

[0040] RNTI: Radio Network Temporary Identifier is a type of identification number. We typically use this identification number to distinguish one thing from all other similar things.

[0041] MAC CE: Medium Access Control (MAC) Control Element (CE) is a MAC structure that carries special control information.

[0042] RSSI: Received signal strength indicator is a measurement of the power present in a received radio signal.

[0043] RSRP: Reference Signal Receive Power is the average power of a resource element (RE) carrying a cell-specific reference signal (RS) over the entire bandwidth.

[0044] Specifically, small data transmission in the deactivated state has been approved as a new Release 17 (Rel-17) work item (WI) for NR in RAN Working Group (WG) #86. This means that NR will support UEs performing infrequent (periodic and / or non-periodic) data transmissions in the RRC_INACTIVE state. More specifically, for UL data transmission, the UE does not move / switch to the RRC_CONNECTED state. Therefore, the UE and / or gNB can avoid unnecessary power consumption and signaling overhead. Currently, three features have been specified as part of Release 15 (Rel-15) and Release 16 (Rel-16), namely, the 2-step and 4-step RACH procedures and the authorization type 1 configuration. This WI builds upon these features to implement small data transmission in the RRC_INACTIVE state for NR.

[0045] In some implementations, the gNB may not schedule any resources for devices in the RRC_IDLE or RRC_INACTIVE state to avoid wasting resources. Therefore, in one implementation, the RACH procedure can be used to connect to a cell (or BS) when a device (e.g., a UE) wants to connect to the gNB and initiate data transmission. Once the device has detected the cell (and is camped on it), it can initiate the RACH procedure to access the cell. Typically, a four-step RACH procedure (or 4-step RACH procedure) is applied to LTE and NR, and it is presented in the following four steps.

[0046] Step 1 (Message 1 / Msg-1): The device (e.g., UE) transmits the Physical Random Access Channel (PRACH) preamble associated with the Random Access RNTI (RA-RNTI) to the gNB.

[0047] Step 2 (Message 2 / Msg-2): The gNB (or eNB) transmits a Random Access Response (RAR) to indicate the reception of the preamble. Additionally, the RAR carries resource allocation information for the next step, such as Message 3 transmitted by the UE.

[0048] Step 3 (Message 3 / Msg-3): Once the device successfully decodes the RAR content, it sends Message 3 to the gNB (or eNB) to request an RRC connection.

[0049] Step 4 (Message 4 / Msg-4): The gNB (or eNB) transmits the Physical Downlink Shared Channel (PDSCH) carrying Message 4 to transition the device to the RRC_CONNECTED state. The Contention Resolution ID (CRID) MAC CE can be included in Message 4 for contention resolution.

[0050] Once the RACH process is complete, the device is in the RRC_CONNECTED state and can begin gNB-device communication using a schedule-based transport.

[0051] In Rel-16, a two-step RACH procedure (or simply 2-step RACH procedure) was discussed in 3GPP to reduce the latency and overhead of the conventional four-step RACH procedure. The two-step RACH procedure is also beneficial for small data transmissions. Please refer to [link / reference needed]. Figure 1 This illustrates a 2-step RACH process formed by a 4-step RACH process according to an exemplary embodiment of the present disclosure. In some embodiments, such as Figure 1 As shown, some steps of the 4-step RACH process are combined to form a 2-step RACH process, which can effectively save, for example, the number of transmissions. Specifically, Msg-1 can be combined with Msg-3 to form Msg-A in a 2-step RACH process, and Msg-2 can be combined with Msg-4 to form Msg-B in a 2-step RACH process. Note that the RA response included in Msg-B may be different from the RA response included in Msg-2.

[0052] With the increasing number of small and infrequent data traffic types, such as those from instant messaging services, wearable devices, and smart meters, signaling overhead has become a significant issue. This not only impacts network performance / efficiency but also UE battery life, thus necessitating support for small data transmissions when the UE operates in the RRC_INACTIVE state before switching to the RRC_CONNECTED state.

[0053] In some implementations, small data transmissions are disclosed to be performed by a UE in the RRC_INACTIVE state instead of the RRC_CONNECTED state via a 2-step RACH procedure, a 4-step RACH procedure, or pre-configured PUSCH resources (e.g., by providing a configured authorization type 1 configuration) to avoid unnecessary signal overhead and power consumption. Therefore, several fundamental issues need to be addressed to support small data transmissions in the RRC_INACTIVE state.

[0054] Regarding the first question, if small data transmissions are performed infrequently via a 2-step RACH process, a 4-step RACH process, and / or a configured authorization type 1, it may be important that the gNB can identify that the received data is infrequent small data or other scheduled data (e.g., small data or RRC messages carried in Msg-A and Msg-3).

[0055] In some implementations, for NR's 2-step and 4-step RACH procedures, the UE can move / switch to the RRC_CONNECTED state after completing the RACH procedure. However, the primary motivation for small data transmission is to enable the UE to transmit small payloads in the RRC_INACTIVE state without switching to the RRC_CONNECTED state, thereby reducing power consumption and signaling overhead. Under this motivation, the NW may need to identify whether the currently received data is for small data transmission or for scheduling the RACH procedure.

[0056] Regarding the second question, the mechanism for determining whether small data transmission has been successfully decoded on the gNB side is likely important. In some implementations, such as those performed via the common RACH procedure, the UE can operate in the RRC_CONNECTED state when it receives a successRAR during a 2-step RACH process or a Msg-4 (contention resolution) during a 4-step RACH process. Similarly, when operating for small data transmission, an indicator may also be needed to notify the UE of successful transmission. Therefore, the mechanism for notifying the UE that small data transmission has been successfully decoded on the gNB side can be described in the following paragraphs.

[0057] Therefore, there are two fundamental questions: (1) how to identify RRC messages (e.g., RACH transmission / data transmission) and small data transmission, and (2) how to form a mechanism to notify the UE that small data transmission has been completed, which are disclosed in the following paragraphs.

[0058] Small data transmission identifier

[0059] In some implementations, the NW can configure dedicated physical resources (e.g., time, frequency, code, preamble, RACH occasion (RO), or PUSCH occasion (PO), which are not limited to the following) for small data transmission to the UE (e.g., via dedicated signaling or via broadcast system information). In one implementation, the NW can schedule a dedicated RO for small data transmission to the UE and notify the UE of the existence of a dedicated RO for small data transmission via broadcast system information (SI). The UE performing the small data transmission can then pick up the preamble in the dedicated RO for small data transmission and send it to the gNB to initiate the small data transmission.

[0060] In some implementations, the NW can be configured with dedicated preambles for small data transmission (e.g., via dedicated signaling or via broadcast system information). In some implementations, dedicated RA resources can be provided to the UE in an RRC release message (e.g., an RRC release message with / without abort configuration) for transmitting (small) data in the RRC_INACTIVE state. Dedicated RA resources can be dedicated preambles, dedicated ROs, and / or dedicated PUSCH resources (e.g., the payload portion of Msg-A). For dedicated preambles, these preambles can be obtained from all used preambles in the NR, and these preambles can be used solely for small data transmission. In some implementations, preambles can be shared for different purposes, such as small data transmission, a 4-step RACH procedure, a 2-step RACH procedure, etc. For example, the gNB can schedule some preambles, such as preambles #0 to #20 out of 64 preambles, for a 2-step RACH procedure (e.g., for RRC connection establishment or recovery) and for small data transmission via a 2-step RACH procedure at the same RO. In some implementations, if a shared preamble is selected, the associated PUSCH may carry information to assist the gNB in ​​identifying whether the purpose is for small data transmission via a 2-step RACH procedure or for RRC connection establishment / recovery via a 2-step RACH procedure. If a shared preamble is picked up for RRC connection establishment / recovery via a 2-step RACH procedure, the 2-step RACH procedure as defined in Rel-16 may be triggered (e.g., as described in 3GPP Technical Specification (TS) 38.321).

[0061] In some implementations, a dedicated preamble group can be configured for the purpose of small data transmission. A UE intending to transmit small data in the RRC_INACTIVE state can use the dedicated preamble group to indicate that the purpose of the initiated RACH procedure is for small data transmission.

[0062] In some implementations, the NW can provide the UE with pre-configured PUSCH resources to transmit small data in the RRC_INACITIVE state. In some implementations, the authorized configuration scheduled by the NW can be used only for small data transmission. In some implementations, the authorized configuration allocated by the NW is used not only for small data transmission but also for other data transmissions (e.g., Ultra-Reliable Low-Latency Communication (URLLC) data transmission).

[0063] In some implementations, a unique UE identifier (e.g., an inactive-RNTI or a 5GS-Temporary Mobile Subscription Identifier) ​​or related UE identification information can be used to identify whether received data at the gNB side is associated with small data transmission. For example, if the gNB recognizes that an I-RNTI is included in the content of the received data, the current received data can be considered small data. In some implementations, for (small) data transmission in the RRC_INACITIVE state via a 2-step RACH procedure, the UE can include an I-RNTI MAC CE in the payload of Msg-A. In some implementations, for (small) data transmission in the RRC_INACITIVE state via a 4-step RACH procedure, the UE can include an I-RNTI MAC CE in Msg-3. In some implementations, for (small) data transmission in the RRC_INACTIVE state via pre-configured PUSCH resources, the UE can include an I-RNTI MAC CE in the selected PUSCH resource used for data transmission. In some implementations, the I-RNTI MAC CE may be identified by a MAC sub-header having a specific Logical Channel Identifier (LCID). In some implementations, the I-RNTI MAC CE may have an ID field to indicate the UE's full I-RNTI. In some implementations, the I-RNTI MAC CE may have an ID field to indicate the UE's short I-RNTI. In some implementations, the I-RNTI MAC CE for the full I-RNTI may be identified by a MAC sub-header having a specific LCID (e.g., 51), and another I-RNTI MAC CE for the short I-RNTI may be identified by a MAC sub-header having another LCID (e.g., 50). In some implementations, whether to include an I-RNTI MAC CE for the full I-RNTI or an I-RNTI MAC CE for the short I-RNTI may be determined based on NW commands (e.g., via dedicated signaling or SI).

[0064] In some implementations, the gNB may send an Acknowledgement (ACK) indicator to the UE to notify the UE that data transmitted in the RRC_INACTIVE state has been successfully decoded / received. In some implementations, when the UE receives an ACK indicator associated with small data transmitted in the RRC_INACTIVE state, the UE may consider the (small) data transmission successful and not require retransmission. In some implementations, the gNB may send an ACK indicator and a new configuration (e.g., an RRC version with suspendConfig) to the UE to notify the UE that data transmitted in the RRC_INACTIVE state has been successfully decoded / received. In some implementations, when the UE receives an ACK indicator associated with small data transmitted in the RRC_INACTIVE state and a new configuration, the UE may consider the (small) data transmission successful and apply the new configuration for the RRC_INACTIVE state.

[0065] In some implementations, the RRC ResumeRequest message may be transmitted as a small data transfer to notify the NW in Msg-A (for a 2-step RACH procedure) or in Msg-3 (for a 4-step RACH procedure) with a new recovery reason. If the recovery reason is a "small data transfer", the NW may send an RRC release with suspendConfig to the UE.

[0066] In some implementations, if the UE has one or more small data packets to transmit to the gNB, or if the PUSCH resources cannot accommodate the small data packets, the UE may request additional UL authorization for the transmission of another small data packet or the remaining data transmission. For example, the UE may notify the NW via a MAC CE or RRC message that it has other incoming small data packets in the 2-step RACH Msg-A PUSCH.

[0067] In some implementations, in response to a UE's request for additional UL authorization, the gNB may send an existing RAR with modifications (e.g., using reserved bits in the existing MAC RAR (or RAR payload) to inform the UE that the scheduled UL authorization granted to the UE via that MAC RAR (or RAR payload) has been used for new data transmission, data retransmission, or remaining data transmission for small data transmissions). In some implementations, the gNB may use a new MAC RAR (or RAR payload) for the UE to send another small data packet or remaining data. Note that in some implementations, the (Msg-B) MAC packet or Protocol Data Unit (PDU) may include one or more MAC sub-PDUs and optionally padding. In one implementation, each MAC sub-PDU includes one of the following:

[0068] ■ MAC subheader with only backoff indicator;

[0069] ■MAC subheader and fallback RAR;

[0070] ■MAC subheader and successRAR;

[0071] ■ MAC subheader and MAC service data unit (SDU) used for the Common Control Channel (CCCH) or Dedicated Control Channel (DCCH).

[0072] In some implementations, the gNB can use fallbackRAR to schedule additional UL grants for the UE in order to transmit the next small data or remaining data. Please refer to [link to relevant documentation]. Figure 2 This illustrates a fallback RAR format 20 according to an exemplary embodiment of the present disclosure. In one embodiment, as... Figure 2 As shown, rollback RAR format 20 may include the following fields:

[0073] ■R: This field represents a reserved bit, which is set to "0";

[0074] ■Timing Advance Command: This field indicates the index value Timing Advance (TA), which controls the amount of timing adjustment that the MAC entity must apply (e.g., in 3GPP Technical Specification (TS) 38.213 v15.7.0). The Timing Advance Command field is 12 bits in size;

[0075] ■UL Authorization: This field indicates the resources that will be used on UL, such as in 3GPP TS 38.213v15.7.0. The UL Authorization field is 27 bits in size;

[0076] ■ Temporary C-RNTI (Cell-RNTI): This field indicates a temporary identifier used by the MAC entity during random access (RA). The temporary RNTI field is 16 bits in size.

[0077] In some implementations, reserved bits may be used to indicate the type of data transmitted in UL authorization (indicated in the UL authorization field). In some implementations, the type of data transmission may be new data transmission (e.g., for the next small data or other portions of the remaining data), retransmission of previous small data, or common 2-step / 4-step RACH data transmission (e.g., Msg-A payload retransmission), which is not limited below.

[0078] In some implementations, the gNB can use successRAR to schedule additional UL grants for the UE to transmit the next small data transmission or the remaining data from a small data transmission. Please refer to [link to relevant documentation]. Figure 3 This illustrates a successful RAR (successRAR) format 30 according to an exemplary embodiment of this disclosure. In one embodiment, such as Figure 3 As shown, a successful RAR format 30 can consist of the following fields:

[0079] ■UE Contention Resolution Identifier: This field contains the UL CCCH SDU. If the UL CCCH SDU is longer than 48 bits, this field contains the first 48 bits of the UL CCCH SDU.

[0080] ■R: This field represents a reserved bit, which is set to "0";

[0081] ■TPC: This field represents a TPC command used for PUCCH resources containing feedback for a Hybrid Automatic Repeat reQuest (HARQ) request for Msg-B, such as as specified in 3GPP TS38.213v15.7.0. The TPC field is 2 bits in size;

[0082] ■ Timing Advance Command: This field indicates the index value TA, which controls the amount of timing adjustment that the MAC entity must apply (e.g., in 3GPP TS 38.213v15.7.0). The Timing Advance Command field is 12 bits in size;

[0083] ■C-RNTI: This field indicates the identifier used by the MAC entity when the RA is completed. The C-RNTI field is 16 bits in size.

[0084] In some implementations, the UL grant field may be included in a successful RAR to schedule additional UL grants for new data transmission (e.g., for the next small data or the remaining data after a small data transmission). In some implementations, the presence of the UL grant field in a successful RAR may depend on notification from the UE. For example, if the received UE contention resolution identifier field matches a CCCH SDU, a UE requesting additional UL grants in the first PUSCH resource (e.g., in the PUSCH of Msg-A or Msg-3) can determine that the UL grant field is present. In some implementations, reserved bits in the subheader of a successful RAR may be used to indicate whether the associated successful RAR includes the UL grant field. Please refer to [link to relevant documentation]. Figure 4 This illustrates another successful RAR MAC subheader format 40 according to an exemplary embodiment of this disclosure. In one embodiment, as... Figure 4 As shown, the successful RAR MAC subheader format 40 may include the following fields:

[0085] ■E (Extensio): This field is a flag that, if included in a MAC sub-PDU, indicates that the MAC sub-PDU is the last one (other than the MAC sub-PDU used for the MAC SDU) or that the MAC sub-header is not in the MAC PDU. An E field of "1" indicates that at least one other MAC sub-PDU follows (other than the MAC sub-PDU used for the MAC SDU). An E field of "0" indicates that the MAC sub-PDU containing the MAC sub-header is the last MAC sub-PDU in the MAC PDU set (other than the MAC sub-PDU used for the MAC SDU).

[0086] ■T1: This field indicates whether the MAC subheader contains the RA preamble ID or T2. A T1 value of "1" indicates the presence of the RA preamble ID (RAPID) field in the subheader. A T1 value of "0" indicates the presence of the T2 field in the subheader.

[0087] ■T2: This field indicates whether the MAC subheader contains a Backoff Indicator (BI) or a MAC SDU (S) indicator. A T2 field of "0" indicates the presence of the Backoff Indicator field in the subheader. A T2 field of "1" indicates the presence of the S field in the subheader.

[0088] ■S: This field indicates whether the "MAC sub-PDU for MAC SDU" is followed by a MAC sub-PDU containing this MAC sub-header. An S field of "1" indicates the presence of the "MAC sub-PDU for MAC SDU". An S field of "0" indicates the absence of the "MAC sub-PDU for MAC SDU".

[0089] ■R: In some implementations, one of the reserved bits can be used to indicate whether a UL authorization field exists.

[0090] In some implementations, the gNB may provide UL authorization to the UE via a new DCI format scrambled with an available I-RNTI, 5G-S-TMSI, or a new RNTI associated with small data transmission (or an existing DCI format with different field descriptions), but is not limited thereto. In some implementations, after receiving a successful RAR associated with the transmitted preamble, the UE may begin listening to control resource set #0 (CORESET#0) (or other configured CORESET) addressed to C-RNTI (or I-RNTI). If no DCI is received within a timer period, the UE may determine that the 2-step RACH procedure has ended and remain in the RRC_INACTIVE state. The UE may then stop listening to CORESET#0 (or other configured CORESET) addressed to C-RNTI (or I-RNTI).

[0091] In some implementations, if the UE no longer has small data to transmit, the UE may send an indication or message (e.g., in an RRC message, MAC CE, or DCI) to notify the gNB that the UE does not need more resources to transmit (small) data. In some implementations, the UE may set a new resumeCause in an RRC Resume Request message. For example, the UE may set the resumeCause to small data transmission and include it in an RRC Resume Request or RRC Resume Request1 to notify the gNB (or cell) that the transmission is intended for small data transmission. In some implementations, the gNB may send an RRC Release with suspendConfig to the UE. In some implementations, the gNB may send a new configuration to the UE for subsequent (small) data transmission.

[0092] In some implementations, new RRC parameters can be used for small data transfers. For example, new RRC parameters can represent the preamble group used for small data transfers, the number of ROs and POs used for small data transfers, or the number of preambles used for small data transfers.

[0093] In some implementations, the transmitted small data may carry the UE's I-RNTI for UE / device identification purposes, wherein the I-RNTI may include, for example, a full I-RNTI and / or a short I-RNTI. In some implementations, the full I-RNTI may be used for small data transmission to identify the UE / device. In some implementations, the short I-RNTI may be used for small data transmission to identify the UE / device. In some implementations, if the useFullResumeID field is signaled in SIB1, the full I-RNTI may be used for small data transmission to identify the UE / device; otherwise, the short I-RNTI may be used for small data transmission to identify the UE / device.

[0094] In some implementations, the NW can broadcast a threshold so that the UE can determine whether it can transmit data in the RRC_INACTIVE state. In some implementations, the threshold can be, but is not limited to, Reference Signal Received Power (RSRP), Reference Signal Received Quality (RSRQ), Received Signal Strength Indication (RSSI), Layer 2 buffer size, transmitted payload size, or type of radio bearer (e.g., signaling radio bearer, data radio bearer). In some implementations, when the measured RSSI value is greater than the RSSI threshold broadcast during the 2-step RACH procedure, the UE can determine whether to perform a small data transmission.

[0095] On the UE side, the UE's upper layer (e.g., the MAC entity) may need to determine whether the current transmission is for small data transmission via a 2-step / 4-step RACH procedure or for connection establishment / recovery via a 2-step / 4-step RACH procedure. In some implementations, the UE's upper layer can determine whether the transmitted data is small data based on the bits transmitted in the PUSCH. If the transmitted data is not small data, the UE may need to request connection setup / recovery to switch to the RRC_CONNECTED state. For example, in some implementations, if the number of bits transmitted is less than K bits (e.g., the number of K can be signaled to the UE via an RRC message (or dedicated signaling) or pre-configured / predefined, but is not limited to this), it can be determined as small data transmission. If the number of bits transmitted is greater than K bits, the UE's upper layer can trigger a 2-step RACH procedure or a 4-step RACH procedure to switch the UE to the RRC_CONNECTED state for data transmission. For example, if K is predefined as 1000 and the UE needs to transmit 520 bits, the UE's upper layer can determine the current transmission as small data transmission. If a dedicated preamble for small data transmission exists, the UE's upper layer can pick up the dedicated preamble to notify the lower layer (e.g., the physical layer) to send it to the gNB. The UE can then begin RACH-based small data transmission. If no dedicated preamble exists, the UE's upper layer can randomly select a preamble to request the lower layer to send it to the gNB. Accordingly, the UE can include some information in Msg-A / Msg-3PUSCH to notify the gNB that the current transmission is for small data transmission. In some implementations, the NW may not allow multiplexing between the Data Radio Bearer (DRB) and Signal Radio Bearer (SRB) in the RRC_INACTIVE state. In some implementations, the NW may allow multiplexing between the Data Radio Bearer (DRB) and Signal Radio Bearer (SRB) in the RRC_INACTIVE state.

[0096] In some implementations, if multiplexing of the Signal Radio Bearer (SRB) and DRB is not permitted, the upper layer can determine whether to trigger a small data transmission based on the type of radio bearer (e.g., SRB or DRB) in the RRC_INACTIVE state. For example, if the radio bearer type is a Data Radio Bearer (DRB), the UE's upper layer can trigger a small data transmission. In some implementations, multiplexing between the DRB and SRB is permitted in the RRC_INACTIVE state, and the UE's upper layer can trigger a small data transmission based on the number of bits transmitted. For example, if the number of bits transmitted is greater than Q bits (e.g., the number of Q can be signaled to the UE via an RRC message (or dedicated signaling) or pre-configured / predefined, but is not limited to this), the UE's upper layer can trigger a small data transmission.

[0097] In some implementations, the NW can notify the UE whether the NW has enabled the ability to transmit small data. In some implementations, the NW can transmit RRC messages, dedicated signaling, and / or broadcast SI to notify the UE whether the UE is allowed to transmit data in the RRC_INACTIVE state.

[0098] ACK indicator for small data transfers

[0099] In some implementations, the RAR may carry an ACK indicator to notify the UE that the gNB has successfully received the data. In some implementations, the new RAR may be used to indicate that the UE small data transmission has been completed. Please refer to [link to relevant documentation]. Figure 5 This illustrates a new RAR format 50 according to an exemplary embodiment of the present disclosure. In one embodiment, the new RAR format for a small data transfer ACK indicator may include the following fields:

[0100] ■R: This field represents a reserved bit, which is set to "0".

[0101] ■TPC: This field indicates the TPC command used for PUCCH resources containing HARQ feedback for Msg-B, as specified, for example, in 3GPP TS 38.213v15.7.0. The TPC field is 2 bits in size;

[0102] ■ Timing Advance Command: This field indicates the index value TA, which controls the amount of timing adjustment that the MAC entity must apply (e.g., in 3GPP TS 38.213v15.7.0). The Timing Advance Command field is 12 bits in size.

[0103] In some implementations, existing RARs can be reused with modifications to indicate to the UE that small data transmission has been completed. For example, by using a reserved bit as an ACK indicator, the successRAR can be reused to indicate to the UE that small data transmission has been completed. Please refer to... Figure 6 This illustrates a modified successRAR format 60 according to an exemplary embodiment of the present disclosure. In one embodiment, the modified successRAR format 60 for small data transfer, having an ACK indicator, may include the following fields:

[0104] ■UE Contention Resolution Identifier: This field contains the UL CCCH SDU. If the UL CCCH SDU is longer than 48 bits, this field may contain the first 48 bits of the UL CCCH SDU.

[0105] ■I: This field indicates an indicator to the UE of what the next step is; "1" can indicate stopping transmission; "0" can indicate continuing to receive NW instructions (e.g., using C-RNTI or other RNTI to listen to the Physical Downlink Control Channel (PDCCH)). In some implementations, "0" can indicate stopping transmission; "1" can indicate continuing to receive NW instructions (e.g., using C-RNTI or other RNTI to listen to the PDCCH). In some implementations, the NW can instruct the UE to switch back to the RRC_CONNECTED state by sending an RRC recovery command. In some implementations, the NW can instruct the UE to switch back to the RRC_CONNECTED state by requesting the UE to send an RRC recovery request message. In some implementations, the NW can provide further UL authorization via DCI (e.g., when the UE uses C-RNTI or other RNTI to listen to the PDCCH).

[0106] ■R: This field represents a reserved bit, which is set to "0";

[0107] ■TPC: This field indicates the TPC command used for PUCCH resources containing HARQ feedback for Msg-B, as specified, for example, in 3GPP TS 38.213v15.7.0. The TPC field is 2 bits in size;

[0108] ■ Timing Advance Command: This field indicates the index value TA, which controls the amount of timing adjustment that the MAC entity must apply (e.g., in 3GPP TS 38.213v15.7.0). The Timing Advance Command field is 12 bits in size;

[0109] ■C-RNTI: This field indicates the identifier used by the MAC entity when the RA is completed. The C-RNTI field is 16 bits in size.

[0110] In some implementations, an RNTI, such as I-RNTI, RA-RNTI, TC-RNTI, or other new RNTIs dedicated to small data transmission, can be used to indicate whether the current procedure is for small data transmission. In some implementations, the NW can implicitly notify the UE that data has been successfully received on the gNB side. For example, if the UE can successfully decode the PDCCH via I-RNTI or a new RNTI dedicated to small data transmission, the UE can assume that the gNB has successfully received the data.

[0111] In some implementations, a new RAR can be used to instruct the UE to transmit previous data (e.g., retransmitted data) or new data (e.g., the remaining portion of all data that the UE wants to send to the NW).

[0112] In some implementations, existing RARs, such as fallback RARs and / or success RARs, can be used for data retransmission. In some implementations, reserved bits in existing RARs can be used for retransmission indication. In some implementations, reserved bits in existing RARs can be used to indicate that the UE should transmit the remaining portion of all data it wants to send to the NW.

[0113] In some implementations, the MAC CE of the transmitted data may carry index information for the transmitted data, which can be obtained from the complete data to be sent to the gNB. In some implementations, the UE may use the MAC CE carried in the transmitted data to notify the gNB that the UE does not have other data for transmission.

[0114] In some implementations, when the UE receives a rollback RAR, the UE can retransmit the same data (e.g., the same data from a previous small data transmission) or other new data (e.g., a new small data transmission).

[0115] In some implementations, the UE may carry information indicating whether it requires additional PUSCH resources to transmit data in the MAC CE of the transmitted data. In some implementations, if the MAC CE of the transmitted data indicates that the UE requires additional PUSCH resources, the gNB may send a fallback RAR to the UE.

[0116] In some implementations, the MAC CE of the transmitted data may carry information about the transmitted data, such as the size of the transmitted data, the index of the transmitted data, and the total amount of data that the UE wants to send to the gNB.

[0117] In some implementations, if the UE notifies the gNB that it has more than one data item to transmit during an ongoing RACH-based small data transmission, the gNB may schedule a UL grant for the UE to transmit the data. In some implementations, the UL grant may be obtained from a PDCCH scrambled by an I-RNTI or another new RNTI used for small data transmission. In some implementations, if the UE notifies the gNB that it has more than one data item to transmit during RACH-based small data transmission, the configured grant type 1 may be scheduled to the UE via an RRC message sent by the gNB / cell.

[0118] Figure 7 A small data transmission process 70 by a UE according to an exemplary embodiment of this disclosure is illustrated. Figure 7 As shown, the small data transmission process 70 of the UE includes the following actions:

[0119] ■Action 700: Begin.

[0120] ■Action 702: Receive instructions from the BS regarding the configuration of dedicated physical resources.

[0121] ■Action 704: Perform small data transfer based on dedicated physical resources.

[0122] ■Action 706: Receive indication from BS that the BS has successfully received the ACK indicator for the small data transmission.

[0123] ■Action 708: End.

[0124] Preferably, actions 702 to 706 of the small data transmission process 70 can be applied to the UE. Specifically, in some embodiments, in action 702, the UE can receive a configuration indicating dedicated physical resources from the BS. In one embodiment, the dedicated physical resources can be obtained via dedicated signaling or broadcast system information (SI). In one embodiment, the dedicated physical resources can correspond to RO, preamble, or PO. In one embodiment, the dedicated physical resources may include pre-configured PUSCH resources, a specific identifier, or authorization of configuration requested by the UE. In one embodiment, the specific identifier may be a deactivation I-RNTI.

[0125] In some implementations, during action 704, the UE can perform small data transmission based on dedicated physical resources, wherein the UE can be in a deactivated state to perform small data transmission. In one implementation, the UE can be in a deactivated state to perform a 2-step RACH procedure, a 4-step RACH procedure, or a configured grant (CG) type 1 transmission. In one implementation, the UE can be in a connected state before receiving pre-configured PUSCH resources.

[0126] In some implementations, in action 706, the UE may receive an ACK indicator indicating that the BS has successfully received the small data transmission. In one implementation, the ACK indicator corresponds to the decoding of the RAR or the PDCCH of a specific UE identifier. In one implementation, the specific UE identifier may include one of I-RNTI, Random Access RNTI (RA-RNTI), Cell-RNTI (C-RNTI), or Temporary Cell RNTI (TC-RNTI), and the RAR may include fallbackRAR or successRAR.

[0127] Please refer to Figure 8 This illustrates a block diagram of a node 800 for wireless communication according to an exemplary embodiment of the present disclosure. Figure 8 As shown, node 800 may include a transceiver 806, a processor 808, a memory 802, one or more presentation units 804, and at least one antenna 810. Node 800 may also include a radio frequency (RF) bandgap module, a base station communication module, an NW communication module, a system communication management module, input / output (I / O) ports, I / O components, and a power supply (in... Figure 8 (Not explicitly shown herein). Each of these components may communicate with each other directly or indirectly via one or more buses 824. In one embodiment, node 800 may be a UE or BS performing the various functions disclosed herein, for example, referring to Figure 7 .

[0128] A transceiver 806, which may have a transmitter 816 (e.g., transmitting / transmission circuitry) and a receiver 818 (e.g., receiving / reception circuitry), may be configured to transmit and / or receive time and / or frequency resource allocation information. In one embodiment, the transceiver 806 may 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 806 may be configured to receive data and control channels.

[0129] Node 800 may include a variety of computer-readable media. Computer-readable media can be any available media accessible by Node 800, and includes both volatile (and non-volatile) media, and removable (and non-removable) media. By way of example, and not limitation, computer-readable media may include computer storage media and communication media. Computer storage media includes both volatile (and non-volatile) and removable (and non-removable) media, and can be implemented in any way or by any technology for storing information such as computer-readable media.

[0130] Computer storage media include RAM, ROM, EEPROM, flash memory (or other storage technologies), CD-ROM, Digital Versatile Disk (DVD) (or other optical disc storage devices), magnetic tape cartridges, magnetic tape, disk storage (or other magnetic storage devices), etc. Computer storage media do not include the transmission of data signals. Communication media may typically contain computer-readable instructions, data structures, program modules, or other data in modulated data signals (such as carrier waves or other transmission mechanisms), and include any information transmission medium. The term "modulated data signal" can refer to a signal having one or more characteristics set or altered in a manner that encodes information in the signal. By way of example, and not limitation, communication media include wired media (such as wired NW or direct wired connections) and wireless media (such as acoustic, RF, infrared, and other wireless media). Any previously disclosed combinations should also be included within the scope of computer-readable media.

[0131] Memory 802 may include computer storage media in the form of volatile and / or non-volatile memory. Memory 802 may be removable, non-removable, or a combination thereof. For example, memory 802 may include solid-state memory, hard disk drive, optical disk drive, etc. Figure 8 As shown, memory 802 may store a computer-executable (readable) program 814 (e.g., software code) that, when executed, causes processor 808 to perform various functions disclosed herein, for example, referring to... Figure 7 Alternatively, the computer executable program 814 may not be executed directly by the processor 808, but may be configured to cause the node 800 (e.g., when compiled and executed) to perform the various functions disclosed herein.

[0132] Processor 808 (e.g., having processing circuitry) may include intelligent hardware devices, such as a central processing unit (CPU), microcontroller, ASIC, etc. Processor 808 may include memory. Processor 808 can process data 812 received from memory 802 and computer-executable programs 814, as well as information transmitted via transceiver 806, baseband communication module, and / or NW communication module. Processor 808 can also process information to be transmitted to transceiver 806 for transmission via antenna 810, and information to be transmitted to NW communication module for transmission to CN.

[0133] One or more presentation components 804 may present data indications to a person or other device. Examples of presentation components 804 may include display devices, speakers, printing components, vibrating components, etc.

[0134] As can be seen from previous disclosures, various techniques can be used to implement these concepts without departing from the scope of the concepts described herein. Furthermore, although the concepts have been disclosed by specific reference to certain embodiments, those skilled in the art will recognize that changes in form and detail can be made without departing from the scope of these concepts. Therefore, the disclosed embodiments should be considered illustrative rather than restrictive in all respects. It should also be understood that this application is not limited to the specific disclosed embodiments. Rather, many rearrangements, modifications, and substitutions are possible without departing from the scope of this disclosure.

Claims

1. A method for small data transmission executed by a user equipment (UE), the method comprising: Receive from base station BS the configuration of the dedicated random access channel RACH timing RO for the small data transmission; The BS receives a threshold related to the data volume, which is used to determine whether to perform the small data transmission. When the UE is in a deactivated state, the small data transmission is performed based on the dedicated RO; as well as The BS receives an ACK indicator indicating that it has successfully received the small data transmission. The ACK indicator is included in the Random Access Response (RAR).

2. The method according to claim 1, characterized in that, The dedicated RO is obtained through dedicated signaling or broadcast system information SI.

3. The method according to claim 1, characterized in that, The ACK indicator is decoded from a specific UE identifier on the Physical Downlink Control Channel (PDCCH).

4. The method according to claim 3, characterized in that, The specific UE identifier includes one of the following: Deactivation Radio Network Temporary I-RNTI, Random Access RNTI RA-RNTI, Cell-RNTI C-RNTI, or Temporary Cell RNTI TC-RNTI, and the RAR includes fallbackRAR or successRAR.

5. The method according to claim 1, characterized in that, The small data transmission is performed via a two-step RACH process, a four-step RACH process, or a pre-configured Physical Uplink Shared Channel (PUSCH) resource provided by a configured Authorized CG Type 1.

6. A user equipment (UE) in a wireless communication system for small data transmission, the wireless communication system comprising a base station (BS), the UE comprising: At least one processor; as well as At least one memory coupled to the at least one processor, wherein the at least one memory stores a computer-executable program that, when executed by the at least one processor, causes the UE to: The BS receives an indication of the configuration of the dedicated random access channel RACH timing RO for the small data transmission; The BS receives a threshold related to the data volume, which is used to determine whether to perform the small data transmission. When the UE is in a deactivated state, the small data transmission is performed based on the dedicated RO; as well as The BS receives an ACK indicator indicating that it has successfully received the small data transmission. The ACK indicator is included in the Random Access Response (RAR).

7. The UE according to claim 6, characterized in that, The dedicated RO is obtained through dedicated signaling or broadcast system information SI.

8. The UE according to claim 6, characterized in that, The ACK indicator is decoded from a specific UE identifier on the Physical Downlink Control Channel (PDCCH).

9. The UE according to claim 8, characterized in that, The specific UE identifier includes one of the following: Deactivation Radio Network Temporary I-RNTI, Random Access RNTI RA-RNTI, Cell-RNTI C-RNTI, or Temporary Cell RNTI TC-RNTI, and the RAR includes fallbackRAR or successRAR.

10. The UE according to claim 6, characterized in that, The small data transmission is performed via a two-step RACH process, a four-step RACH process, or a pre-configured Physical Uplink Shared Channel (PUSCH) resource provided by a configured Authorized CG Type 1.

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