Method and apparatus for small data transmission by reduced capability UE using configuration resources in wireless communication system

Abstract

The present disclosure relates to a 5G or 6G communication system for supporting a higher data transmission rate. Specifically, the present disclosure provides a method and apparatus for an SDT procedure using configuration resources in a wireless communication system. According to various embodiments of the present disclosure, an SDT procedure using a configuration resource (or a configuration grant resource) may be effectively enhanced for a UE.

Description

Technical Field

[0001] The present disclosure relates to a wireless communication system (or mobile communication system), and in particular to an apparatus, method, and system for a reduced capability (RedCap) terminal in the wireless communication system to use configured resources (or configured authorized resources) for small data transmission (SDT). Background Art

[0002] 5G mobile communications technology defines a wide frequency band, enabling high transmission rates and new services. This technology can be implemented not only in "sub-6 GHz" frequency bands such as 3.5 GHz, but also in "above 6 GHz" frequency bands, known as millimeter waves, including 28 GHz and 39 GHz. Furthermore, to achieve transmission rates 50 times faster than 5G mobile communications technology and ultra-low latency one-tenth that of 5G mobile communications technology, consideration has been given to implementing 6G mobile communications technology in the terahertz (THz) frequency band (e.g., the 95 GHz to 3 THz band) (referred to as a "beyond 5G system").

[0003] In the early stages of 5G mobile communication technology development, in order to support services and meet performance requirements associated with enhanced mobile broadband (eMBB), ultra-reliable low-latency communications (URLLC) and massive machine-type communications (mMTC), there has been ongoing standardization on beamforming and massive MIMO for mitigating radio wave path loss and increasing radio wave transmission distance in millimeter waves, supporting dynamic operation of digital (e.g., operating multiple subcarrier spacings) and time slot formats for efficient utilization of millimeter wave resources, initial access technology for supporting multi-beam transmission and broadband, definition and operation of BWP (bandwidth part), new channel coding methods such as LDPC (low-density parity check) codes for large-scale data transmission and polar codes for highly reliable transmission of control information, L2 preprocessing, and network slicing for providing dedicated networks dedicated to specific services.

[0004] Currently, discussions are underway on improvements and performance enhancements to initial 5G mobile communication technologies in consideration of the services they will support, and there has been standardization of physical layers for technologies such as V2X (Vehicle-to-Everything) for assisting driving determination of autonomous vehicles based on information about the location and status of vehicles transmitted by vehicles and for enhancing user convenience, NR-U (New Radio Unlicensed) aimed at system operation in unlicensed bands that complies with various regulatory requirements, NR UE power saving, UE-satellite direct communication for providing coverage in areas where communication with terrestrial networks is unavailable, and non-terrestrial networks (NTN) for positioning.

[0005] In addition, standardization is already underway in the air interface architecture / protocol area, such as the Industrial Internet of Things (IIoT) for supporting new services through interworking and integration with other industries, IAB (Integrated Access and Backhaul) for providing nodes for network service area expansion by supporting wireless backhaul links and access links in an integrated manner, mobility enhancements including conditional handover and DAPS (Dual Active Protocol Stack) handover, and two-step random access (NR's 2-step RACH) for simplifying the random access procedure. Standardization is also underway on the 5G baseline architecture (e.g., service-based architecture or service-based interface) for combining network function virtualization (NFV) and software-defined networking (SDN) technologies, as well as the system architecture / services of Mobile Edge Computing (MEC) for receiving services based on UE location.

[0006] With the commercialization of 5G mobile communication systems, an exponentially increasing number of connected devices will be connected to the communication network. Therefore, it is expected that enhanced functionality and performance of 5G mobile communication systems and the integrated operation of connected devices will become necessary. To this end, new research related to extended reality (XR) is planned to effectively support AR (augmented reality), VR (virtual reality), MR (mixed reality), etc., and to improve 5G performance and reduce complexity by utilizing artificial intelligence (AI) and machine learning (ML), AI service support, metaverse service support, and drone communication.

[0007] Furthermore, such development of 5G mobile communication systems will serve as the basis for developing not only new waveforms for providing terahertz band coverage for 6G mobile communication technology, multi-antenna transmission technologies (such as full-dimensional MIMO (FD-MIMO), array antennas, and large antennas), metamaterial-based lenses and antennas for improving terahertz band signal coverage, high-dimensional spatial multiplexing technologies using OAM (orbital angular momentum), and RIS (Reconfigurable Smart Surfaces), but also full-duplex technologies for improving the frequency efficiency of 6G mobile communication technology and improving system networks, AI-based communication technologies for achieving system optimization by leveraging satellites and AI (artificial intelligence) from the design stage and internalizing end-to-end AI support functions, and next-generation distributed computing technologies for realizing services with a level of complexity that exceeds the limits of UE operating capabilities by utilizing ultra-high-performance communication and computing resources. Summary of the Invention

[0008] Technical issues

[0009] Recently, there is a need to enhance the small data transfer process with respect to configuration resources.

[0010] Solution to the problem

[0011] Aspects of the present disclosure are to address at least the above-mentioned problems and / or disadvantages and provide at least the advantages described below. Therefore, one aspect of the present disclosure is to provide a communication method and system for integrating a fifth generation (5G) communication system to support higher data rates than the fourth generation (4G).

[0012] According to one aspect of the present disclosure, a method performed by a terminal is provided. The method includes: receiving a radio resource control (RRC) release message including a suspension configuration from a base station, the RRC release message including information about configuration grant (CG) resources for small data transmission (SDT); identifying an uplink carrier for SDT data based on satisfying an SDT criterion; identifying an SDT process for the SDT data in a CG-SDT process and a random access (RA)-SDT process; and transmitting the SDT data to the base station on the uplink carrier according to the SDT process.

[0013] According to another aspect of the present disclosure, a terminal is provided. The terminal includes: a transceiver; and a controller coupled to the transceiver and configured to: receive a radio resource control (RRC) release message including a suspension configuration from a base station, the RRC release message including information about configuration grant (CG) resources for small data transmission (SDT), identify an uplink carrier for SDT data based on satisfying an SDT criterion, identify an SDT process for the SDT data in a CG-SDT process and a random access (RA)-SDT process, and transmit the SDT data to the base station on the uplink carrier according to the SDT process.

[0014] Advantageous Effects of the Invention

[0015] According to various embodiments of the present disclosure, an SDT process using configured resources (or configured granted resources) may be effectively enhanced for a UE. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The above and other aspects, features and advantages of certain embodiments of the present disclosure will become more apparent from the following description taken in conjunction with the accompanying drawings, in which:

[0017] Figure 1 An example of a Configuration Grant (CG) SDT process according to an embodiment of the present disclosure is shown.

[0018] Figure 2 Another example of a CG-SDT process according to an embodiment of the present disclosure is shown.

[0019] Figure 3 An example of medium access control (MAC) protocol data unit (PDU) and radio network temporary identifier (RNTI) usage according to an embodiment of the present disclosure is shown.

[0020] Figure 4 is a block diagram of a terminal according to an embodiment of the present disclosure.

[0021] Figure 5 is a block diagram of a base station according to an embodiment of the present disclosure.

[0022] Throughout the drawings, like reference numerals will be understood to refer to like parts, components and structures. DETAILED DESCRIPTION

[0023] The following description, with reference to the accompanying drawings, is provided to facilitate a comprehensive understanding of the various embodiments of the present disclosure as defined by the claims and their equivalents. It includes various specific details to assist understanding, but these are to be regarded as exemplary only. Therefore, those skilled in the art will recognize that various changes and modifications may be made to the various embodiments described herein without departing from the scope and spirit of the present disclosure. Furthermore, descriptions of well-known functions and structures may be omitted for clarity and conciseness.

[0024] The terms and words used in the following description and claims are not limited to the bibliographical meanings, but are merely used by the inventor to enable a clear and consistent understanding of the present disclosure. Therefore, it will be apparent to those skilled in the art that the following description of various embodiments of the present disclosure is provided for illustration purposes only and not for the purpose of limiting the present disclosure as defined by the appended claims and their equivalents.

[0025] It is to be understood that the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to "a component surface" includes reference to one or more of such surfaces.

[0026] The term "substantially" means that the stated characteristic, parameter or value need not be achieved precisely, but deviations or variations including, for example, tolerances, measurement errors, measurement precision limitations and other factors known to those skilled in the art may occur in amounts that do not negate the effect that the characteristic is intended to provide.

[0027] Those skilled in the art will appreciate that the blocks of a flowchart (or sequence diagram) and the combination of the flowchart can be represented and executed by computer program instructions. These computer program instructions can be loaded onto a processor of a general-purpose computer, a special-purpose computer, or a programmable data processing device. When the loaded program instructions are executed by the processor, they create means for performing the functions described in the flowchart. Because computer program instructions can be stored in a computer-readable memory available in a special-purpose computer or a programmable data processing device, an article of manufacture can also be created that performs the functions described in the flowchart. Because the computer program instructions can be loaded onto a computer or a programmable data processing device, when executed as a process, they can perform the operations of the functions described in the flowchart.

[0028] The blocks of the flowchart may correspond to modules, segments or codes containing one or more executable instructions that implement one or more logical functions, or may correspond to portions thereof. In some cases, the functions described by the blocks may be performed in an order different from the order in which they are listed. For example, two blocks listed in order may be executed simultaneously or in reverse order.

[0029] Throughout this specification, the terms "unit," "module," and the like may refer to software or hardware components, such as a field-programmable gate array (FPGA) or application-specific integrated circuit (ASIC) capable of performing a function or operation. However, "unit," etc., is not limited to hardware or software. Units, etc., may be configured to reside in an addressable storage medium or drive one or more processors. Units, etc., may refer to software components, object-oriented software components, class components, task components, processes, functions, attributes, procedures, subroutines, program code segments, drivers, firmware, microcode, circuits, data, databases, data structures, tables, arrays, or variables. The functions provided by components and units may be combinations of smaller components and units, and may be combined with other components and units to form larger components and units. Components and units may be configured to drive devices or one or more processors in a secure multimedia card.

[0030] Before the detailed description, terms or definitions necessary for understanding the present disclosure are described. However, these terms should be interpreted in a non-restrictive manner.

[0031] A "base station (BS)" is an entity that communicates with a user equipment (UE) and may be referred to as a BS, base transceiver station (BTS), node B (NB), evolved NB (eNB), access point (AP), 5G NB (5GNB), or gNB.

[0032] A “UE” is an entity communicating with a BS and may be referred to as a UE, a device, a mobile station (MS), a mobile equipment (ME), or a terminal.

[0033] In fifth-generation wireless communication systems operating in higher-frequency (millimeter wave) bands, UEs and gNBs use beamforming for intercommunication. Beamforming technology is used to mitigate propagation path loss and increase the propagation range of higher-frequency communications. Beamforming uses high-gain antennas to enhance both transmission and reception performance. Beamforming can be categorized as transmit (TX) beamforming, performed on the transmitter side, and receive (RX) beamforming, performed on the receiver side. TX beamforming generally increases directivity by using multiple antennas to densely distribute the area of propagation in a specific direction. In this context, a collection of multiple antennas is referred to as an antenna array, and each antenna in the array is referred to as an array element. Antenna arrays can be configured in various forms, such as linear arrays and planar arrays. The use of TX beamforming increases signal directivity, thereby extending propagation range. Furthermore, since the signal is rarely transmitted in directions other than the directional direction, signal interference at other receivers is significantly reduced. The receiver can perform beamforming on the RX signal using an RX antenna array. RX beamforming increases the strength of RX signals transmitted in a specific direction by concentrating propagation in that direction. It also excludes signals transmitted in directions other than the specific direction from the RX signal, effectively blocking interfering signals. Using beamforming technology, a transmitter can generate multiple transmit beam patterns in different directions. Each of these transmit beam patterns is also referred to as a TX beam. Wireless communication systems operating at high frequencies use multiple narrow TX beams to transmit signals within a cell, as each narrow TX beam covers a portion of the cell. The narrower the TX beam, the higher the antenna gain, thus increasing the propagation distance of signals transmitted using beamforming. A receiver can also generate multiple RX beam patterns in different directions. Each of these receive patterns is also referred to as an RX beam.

[0034] Carrier Aggregation (CA) / Multi-Connectivity in 5G Wireless Communication Systems: 5G wireless communication systems support standalone operation as well as dual connectivity (DC). In DC, multiple Rx / Tx UEs can be configured to utilize resources provided by two different nodes (or base stations) connected via a non-ideal backhaul. One node acts as a master node (MN) and the other as a secondary node (SN). The MN and SN are connected via a network interface, with at least the MN connected to the core network. NR also supports multi-RAT dual connectivity (MR-DC), whereby a UE in a radio resource control (RRC) connection (RRC_CONNECTED) is configured to utilize radio resources provided by two different schedulers located in two different nodes connected via a non-ideal backhaul, providing either Evolved Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access (E-UTRA) (i.e., if the node is an ng-eNB) or NR access (i.e., if the node is a gNB). In NR, for an RRC_CONNECTED UE without CA / DC configured, there is only one serving cell, which is the primary cell. For UEs in RRC_CONNECTED with CA / DC configured, the term "serving cell" is used to refer to the set of cells comprising (multiple) special cells and all secondary cells. In NR, the term "master cell group" (MCG) refers to the set of serving cells associated with a master node, consisting of the primary cell (PCell) and optionally one or more secondary cells (SCcells). In NR, the term "secondary cell group" (SCG) refers to the set of serving cells associated with a secondary node, consisting of the primary SCG cell (PSCell) and optionally one or more SCells. In NR, the PCell refers to the serving cell operating on the primary frequency within the MCG, where the UE either performs an initial connection establishment procedure or initiates a connection re-establishment procedure. In NR for UEs configured with CA, the Scell is the cell that provides additional radio resources over the special cell (SpCell). The PSCell refers to the serving cell within the SCG, where the UE performs random access when performing a synchronized reconfiguration procedure. For dual connectivity operation, the term "SpCell" refers to the pCell of the MCG or the PSCell of the SCG; otherwise, the term "special cell" refers to the PCell.

[0035] PDCCH in the fifth-generation wireless communication system: In the fifth-generation wireless communication system, the physical downlink control channel (PDCCH) is used to schedule downlink (DL) transmission on the physical downlink shared channel (PDSCH) and uplink (UL) transmission on the physical uplink shared channel (PUSCH). The downlink control information (DCI) on the PDCCH includes: downlink allocation including at least modulation and coding format, resource allocation and hybrid automatic repeat request (HARQ) information related to the downlink shared channel (DL-SCH); uplink scheduling grant includes at least modulation and coding format, resource allocation and hybrid ARQ information related to the uplink shared channel (UL-SCH). In addition to scheduling, the PDCCH can be used for: activating and deactivating configured PUSCH transmissions with configured grants; activating and deactivating PDSCH semi-persistent transmissions; notifying one or more UEs of the slot format; notifying one or more UEs of physical resource blocks (PRBs) and orthogonal frequency division multiplexing (OFDM) symbols where the UE can assume no transmissions are intended for the UE; transmitting transmit power control (TPC) commands for PUCCH and PUSCH; transmitting one or more TPC commands for sounding reference signal (SRS) transmission by one or more UEs; switching the active bandwidth portion of a UE; and initiating a random access procedure. A UE monitors a set of PDCCH candidates during configured listening opportunities in one or more configured control resource sets (CORESETs), according to the corresponding search space configuration. A CORESET consists of a set of PRBs with a duration of one to three OFDM symbols. Resource element groups (REGs) and control channel elements (CCEs) are defined within a CORESET, with each CCE consisting of a set of REGs. A control channel is formed by an aggregation of CCEs. Different code rates for the control channel are achieved by aggregating different numbers of CCEs. Both interleaved and non-interleaved CCE-to-REG mappings are supported within the CORESET. Polar decoding is used for the PDCCH. Each resource element group carrying a PDCCH carrier carries its own demodulation reference signal (DMRS). Quadrature Phase Shift Keying (QPSK) modulation is used for the PDCCH.

[0036] In fifth-generation wireless communication systems, the gNB signals a list of search space configurations for each configured BWP, where each search configuration is uniquely identified by an identifier. The identifiers of search space configurations used for specific purposes, such as paging reception, SI reception, and random access response reception, are explicitly signaled by the gNB. In NR, the search space configuration consists of the parameters Monitoring-periodicity-PDCCH-slot, Monitoring-offset-PDCCH-slot, Monitoring-symbols-PDCCH-within-slot, and duration. The UE uses the parameters PDCCH monitoring periodicity (Monitoring-periodicity-PDCCH-slot), PDCCH monitoring offset (Monitoring-offset-PDCCH-slot), and PDCCH monitoring mode (Monitoring-symbols-PDCCH-within-slot) to determine the PDCCH monitoring opportunity(s) within a timeslot. The PDCCH monitoring opportunity exists in time slots "x" to x+duration, where the time slot numbered "x" in the radio frame numbered "y" satisfies the following equation:

[0037] (y*(number of slots in a radio frame)+x-Monitoring-offset-PDCCH-slot)mod(Monitoring-periodicity-PDCCH-slot)=0;

[0038] The starting symbol of a PDCCH listening opportunity in each slot with a PDCCH listening opportunity is given by Listen-Symbol-PDCCH-Slot. The length of a PDCCH listening opportunity (in symbols) is given in the CORESET associated with the search space. The search space configuration includes the identifier of the associated CORESET configuration. The GNB signals a list of CORESET configurations for each configured BWP, where each CORESET configuration is uniquely identified by an identifier. Note that each radio frame lasts 10 ms. A radio frame is identified by a radio frame number or system frame number. Each radio frame consists of several slots, where the number and duration of slots in a radio frame depend on the subcarrier spacing. The number and duration of slots in a radio frame depend on the radio frame for each supported SCS predefined in the NR. Each CORESET configuration is associated with a list of TCI (Transmission Configuration Indicator) states. Each TCI state configuration has a DL reference signal (RS) identifier (synchronization signal and physical broadcast channel block (SSB) or channel state information reference signal (CSI-RS)). The TCI state list corresponding to the CORESET configuration is signaled by the gNB via RRC signaling. A TCI state in the TCI state list is activated and indicated to the UE by the gNB. The TCI state indicates the DL TX beam that the gNB uses to transmit PDCCHs during PDCCH monitoring opportunities in the search space (the DL TX beam is quasi-co-located (QCLed) with the SSB / CSI-RS of the TCI state).

[0039] Bandwidth Part (BWP) Operation in Fifth Generation Wireless Communication Systems: Bandwidth Adaptation (BA) is supported in fifth generation wireless communication systems. With BA, the UE's receive and transmit bandwidth need not be as large as the cell's bandwidth and can be adjusted: the width can be commanded to change (e.g., shrinking during periods of low activity to save power); the location can be moved in the frequency domain (e.g., to increase scheduling flexibility); and the subcarrier spacing can be commanded to change (e.g., to allow for different services). A subset of a cell's total cell bandwidth is called a bandwidth part (BWP). BA is implemented by configuring an RRC-connected UE with one or more BWPs and instructing the UE which configured BWP is currently the active BWP. When BA is configured, the UE only needs to monitor the PDCCH on one active BWP; that is, it does not need to monitor the PDCCH across the entire DL frequency range of the serving cell. In the RRC-connected state, for each configured serving cell (i.e., PCell or SCell), the UE is configured with one or more DL and UL BWPs. For an active serving cell, there is always one active UL and DL BWP at any given time. BWP switching within a serving cell is sometimes used to activate an inactive BWP and deactivate an active BWP. BWP switching is controlled by the PDCCH indicating a downlink assignment or uplink grant, by the bwp-InactivityTimer, by RRC signaling, or by the Medium Access Control (MAC) entity itself when initiating a random access procedure. When adding a SpCell or activating an SCell, the DL BWP and UL BWP, indicated by firstAtiveDownlinkBWP-Id and firstActiveUplinkbwp-Id, respectively, are active without receiving a PDCCH indicating a downlink assignment or uplink grant. The active BWP of the serving cell is indicated by RRC or PDCCH. For unpaired spectrum, the DL BWP is paired with the UL BWP, and BWP switching is common for both UL and DL. Upon expiration of the BWP Inactivity Timer, the UE switches to the active DL BWP, either to the default DL BWP or the initial DL BWP (if one is not configured).

[0040] Random access in fifth-generation wireless communication systems: 5G wireless communication systems support random access (RA). RA is used to achieve uplink (UL) time synchronization. RA is used during initial access, handover, RRC connection reestablishment, scheduling request transmission, secondary cell group (SCG) addition / modification, beam failure recovery, and UL data or control information transmission by unsynchronized UEs in the RRC connected state.

[0041] Contention-based random access (CBRA): This is also known as four-step CBRA. In this type of random access, the UE first transmits a random access preamble (also known as Msg1) and then waits for the RAR within the RAR window. The RAR is also known as Msg2. The GNB transmits the RAR on the PDSCH. The PDCCH that schedules the PDSCH carrying the RAR is addressed to the RA-Radio Network Temporary Identifier (RA-RNTI). The RA-RNTI identifies the time-frequency resource (also known as the physical RA channel (PRACH) opportunity, PRACH TX opportunity, or RA channel (RACH) opportunity) where the RA preamble is detected by the gNB. The RA-RNTI is calculated as follows: RA-RNTI = 1 + s_id + 14 * t_id + 14 * 80 * f_id + 14 * 80 * 8 * ul_carrier_id, where s_id is the index of the first OFDM symbol of the PRACH opportunity in which the UE transmits Msg1, i.e., the RA preamble; 0 ≤ s_id < 14; t_id is the index of the first slot of the PRACH opportunity (0 ≤ t_id < 80); f_id is the frequency domain index of the PRACH opportunity within the slot (0 ≤ f_id < 8); and ul_carrier_id is the UL carrier used for Msg1 transmission (0 for the normal UL (NUL) carrier and 1 for the supplementary UL (SUL) carrier). The gNB can multiplex several RARs for various random access preambles detected by the gNB into the same RAR MAC protocol data unit (PDU). If the RAR includes the RA preamble identifier (RAPID) of the RA preamble transmitted by the UE, the RAR in the MAC PDU corresponds to the RA preamble transmission by the UE. If no RAR corresponding to its RA preamble transmission is received during the RAR window, and the UE has not transmitted the RA preamble a configurable number of times (configured by the gNB in the RACH configuration), the UE returns to the first step, i.e., selecting a random access resource (preamble / RACH opportunity) and transmitting the RA preamble. A fallback may be applied before returning to the first step.

[0042] If the UE receives an RAR corresponding to its RA preamble transmission, it transmits Message 3 (Msg3) within the UL grant received by the RAR. Msg3 includes messages such as RRC Connection Request, RRC Connection Reestablishment Request, RRC Handover Confirm, Scheduling Request, and SI Request. It may include the UE's identity (i.e., Cell Radio Network Temporary Identifier (C-RNTI) or System Architecture Evolution (SAE) Temporary Mobile Subscriber Identity (S-TMSI), or a random number). After sending Msg3, the UE starts the contention resolution timer. While the contention resolution timer is running, if the UE receives a PDCCH addressed to the C-RNTI included in Msg3, contention resolution is considered successful, the contention resolution timer is stopped, and the RA procedure is completed. While the contention resolution timer is running, if the UE receives a contention resolution MAC Control Element (CE) containing the UE's contention resolution identity (the first X bits of the Common Control Channel (CCCH) Service Data Unit (SDU) transmitted in Msg3), contention resolution is considered successful, the contention resolution timer is stopped, and the RA procedure is completed. If the contention resolution timer expires and the UE has not sent an RA preamble for a configurable number of times, the UE returns to the first step, i.e. selecting random access resources (preamble / RACH opportunity) and sending an RA preamble. Before returning to the first step, a fallback may be applied.

[0043] Contention-Free Random Access (CFRA): This is also known as legacy CFRA or four-step CFRA. The CFRA procedure is used in situations such as handovers requiring low latency and establishing timing advance for SCells. The evolved Node B (eNB) allocates a dedicated random access preamble to the UE. The UE sends a dedicated RA preamble. The eNB transmits a Random Access Response (RAR) addressed to the RA-RNTI on the PDSCH. The RAR conveys the RA preamble identifier and timing alignment information. The RAR may also include an UL grant. Similar to the CBRA procedure, the RAR is sent within the RAR window. CFRA is considered successful upon receipt of the UE's RAR, which includes the RAPID of the RA preamble. If RA is initiated for beam failure recovery, CFRA is considered successful if a PDCCH addressed to the C-RNTI is received in the search space used for beam failure recovery. If the RAR window expires and the RA does not complete successfully, and the UE has not sent the RA preamble a configurable number of times (configured by the gNB in the RACH configuration), the UE retransmits the RA preamble.

[0044] For certain events, such as handover and beam failure recovery, if a UE is assigned (multiple) dedicated preambles, it determines whether to transmit a dedicated preamble or a non-dedicated preamble during the first step of random access, namely, during random access resource selection for Msg1 transmission. Dedicated preambles are typically provided for a subset of SSB / CSI-RS. If no SSB / CSI RS with a DL reference signal received power (RSRP) above a threshold is present among the SSB / CSI RSs provided with contention-free random access resources (i.e., dedicated preambles / ROs) by the gNB, the UE selects a non-dedicated preamble. Otherwise, the UE selects a dedicated preamble. Therefore, during the RA procedure, one random access attempt may be CFRA, while the other may be CBRA.

[0045] 2-step Contention-Based Random Access (2-step CBRA): In the first step, the UE transmits a random access preamble on the PRACH and a payload (i.e., MAC PDU) on the PUSCH. The random access preamble and payload transmission is also called MsgA. In the second step, after the MsgA transmission, the UE listens for a response from the network (i.e., the gNB) within a configured window. This response is also called MsgB. The GNB transmits MsgB on the PDSCH. The PDCCH scheduling the PDSCH carrying MsgB is addressed to the MsgB-Radio Network Temporary Identifier (MSGB-RNTI). The MSGB-RNTI identifies the time-frequency resource (also called PRACH opportunity, PRACH TX opportunity, or RACH opportunity) in which the gNB detected the RA preamble. The calculation of MSGB-RNTI is as follows: RA-RNTI = 1+s_id+14*t_id+14*80*f_id+14*80*8*ul_carrier_id+14*80*8*2, where s_id is the index of the first orthogonal frequency division multiplexing (OFDM) symbol of the PRACH opportunity in which the UE sends Msg1, that is, the RA preamble; 0≤s_id<14; t_id is the index of the first time slot of the PRACH opportunity (0≤t_d<0); f_id is the index of the PRACH opportunity in the frequency domain within the time slot (0≤f_id<8), and ul_carrier_id is the UL carrier used for Msg1 transmission (0 for NUL carrier and 1 for SUL carrier).

[0046] If the CCCH SDU is transmitted in the MsgA payload, the UE performs contention resolution using the contention resolution information in MsgB. If the contention resolution identifier received in MsgB matches the first 48 bits of the CCCH SDU transmitted in MsgA, contention resolution is successful. If the C-RNTI is transmitted in the MsgA payload, contention resolution is successful if the UE receives a PDCCH addressed to the C-RNTI. If contention resolution is successful, the random access procedure is considered to have completed successfully. Instead of the contention resolution information corresponding to the transmitted MsgA, MsgB may include backoff information corresponding to the random access preamble transmitted in MsgA. If the backoff information is received, the UE transmits Msg3 and performs contention resolution using Msg4, as in the CBRA procedure. If contention resolution is successful, the random access procedure is considered to have completed successfully. If contention resolution fails at the backoff time (i.e., when transmitting Msg3), the UE retransmits MsgA. If the configured window for the UE to listen to the network response after transmitting MsgA expires and the UE does not receive MsgB including contention resolution information or fallback information as described above, the UE retransmits MsgA. If the random access procedure is not successfully completed even after transmitting MsgA a configurable number of times, the UE falls back to the 4-step RACH procedure, i.e., the UE only transmits the PRACH preamble.

[0047] The MsgA payload may include one or more of a CCCH SDU, a dedicated control channel (DCCH) SDU, a dedicated traffic channel (DTCH) SDU, a buffer status report (BSR) MAC CE, a power headroom report (PHR) MAC CE, SSB information, a C-RNTI MAC CE, or padding. The MsgA may include a UE ID (e.g., random ID, S-TMSI, C-RNTI, recovery ID, etc.) and the preamble in the first step. The UE ID may be included in the MAC PDU of the MsgA. The UE ID, such as the C-RNTI, may be carried in a MAC CE, where the MAC CE is included in the MAC PDU. Other UE IDs (e.g., random ID, S-TMSI, C-RNTI, recovery ID, etc.) may be carried in the CCCH SDU. The UE ID may be one of random ID, S-TMSI, C-RNTI, recovery ID, IMSI, idle mode ID, inactive mode ID, etc. The UE ID may be different in different scenarios where the UE performs the RA procedure. When the UE performs RA after power-on (before it attaches to the network), the UE ID is a random ID. When the UE performs RA in the idle state after attaching to the network, the UE ID is the S-TMSI. If the UE has an assigned C-RNTI (e.g., in the connected state), the UE ID is the C-RNTI. In the case where the UE is in the inactive state, the UE ID is the recovery ID. In addition to the UE ID, some additional ctrl information may be sent in MsgA. Control information may be included in the MAC PDU of MsgA. The control information may include a connection request indication, a connection recovery request indication, an SI request indication, a buffer status indication, beam information (e.g., one or more DL TX beam IDs or SSBs) ID), beam failure recovery indication / information, data indicator, cell / BS / TRP switching indication, connection reestablishment indication, reconfiguration completion or switching completion message, etc.

[0048] 2-step Contention-Free Random Access (2-step CFRA): In this scenario, the gNB allocates dedicated random access preamble(s) and PUSCH resources(s) to the UE for MsgA transmission. It may also indicate the RO(s) to be used for preamble transmission. In the first step, the UE transmits the random access preamble on the PRACH and the payload on the PUSCH using the contention-free random access resources (i.e., dedicated preamble / PUSCH resources / RO). In the second step, after MsgA transmission, the UE listens for a response from the network (i.e., the gNB) within a configured window. This response is also referred to as MsgB.

[0049] The gNB transmits MsgB on the PDSCH. The PDCCH scheduling the PDSCH carrying MsgB is addressed to the MSGB-RNTI. The MSGB-RNTI identifies the time-frequency resource (also known as the PRACH opportunity, PRACH TX opportunity, or RACH opportunity) in which the gNB detects the RA preamble. MSGB-RNTI is calculated as follows: RA-RNTI = 1+s_id+14*t_id+14*80*f_id+14*80*8*ul_carrie_id+14*80*8*2, where s_id is the index of the first orthogonal frequency division multiplexing (OFDM) symbol of the PRACH opportunity in which the UE has transmitted Msg1, that is, the RA preamble; 0≤s_id<14; t_id is the index of the first time slot of the PRACH opportunity (0≤t_id<80); f_id is the index of the PRACH opportunity in the frequency domain within the time slot (0≤f_id<8), and ul_carrier_id is the UL carrier used for Msg1 transmission (0 for NUL carrier and 1 for SUL carrier).

[0050] The random access procedure is considered to be successfully completed if the UE receives a PDCCH addressed to the C-RNTI. The random access procedure is considered to be successfully completed if the UE receives backoff information corresponding to the preamble it transmitted.

[0051] For certain events, such as handover and beam failure recovery, if a UE is assigned dedicated preamble(s) and PUSCH resources(s), the UE determines whether to transmit a dedicated preamble or a non-dedicated preamble during the first step of random access, i.e., random access resource selection during MsgA transmission. Dedicated preambles are typically provided for a subset of SSBs / CSI-RSs. If no SSBs / CSI-RSs with a DL RSRP above a threshold are provided by the gNB for contention-free random access resources (i.e., dedicated preambles / RO / PUSCH resources), the UE selects a non-dedicated preamble. Otherwise, the UE selects a dedicated preamble. Therefore, during the RA procedure, one random access attempt can be a 2-step CFRA, while the other can be a 2-step CBRA.

[0052] When initiating a random access procedure, the UE first selects a carrier (SUL or NUL). If the carrier to be used for the random access procedure is explicitly signaled by the gNB, the UE selects the signaled carrier to perform the random access procedure. If the gNB does not explicitly signal the carrier to be used for the random access procedure, and if the serving cell used for the random access procedure is configured with a supplementary uplink (SUL), and if the RSRP referenced by the downlink pathloss is less than rsrp-ThresholdSSB-SUL, the UE selects the SUL carrier to perform the random access procedure. Otherwise, the UE selects the NUL carrier to perform the random access procedure. After selecting the UL carrier, the UE determines the UL and DL BWPs for the random access procedure. The UE then determines whether to perform a 2-step or 4-step RACH for this random access procedure.

[0053] If the random access procedure is initiated by PDCCH sequence and if the ra-PreambleIndex explicitly provided by PDCCH is not 0b000000, the UE selects 4-step RACH.

[0054] Otherwise, if the gNB signals 2-step contention-free random access resources for this random access procedure, the UE selects 2-step RACH.

[0055] Otherwise, if the gNB signals 4-step contention-free random access resources for this random access procedure, the UE selects 4-step RACH.

[0056] Otherwise, if the UL BWP selected for this random access procedure is only configured with 2-step RACH resources, the UE selects 2-step RACH.

[0057] Otherwise, if the UL BWP selected for this random access procedure is only configured with 4-step RACH resources, the UE selects 4-step RACH.

[0058] - Otherwise if the UL BWP selected for this random access procedure is configured with 2-step and 4-step RACH resources, then

[0059] *If the downlink path loss referenced RSRP is below the configured threshold, the UE selects 4-step RACH. Otherwise, the UE selects 2-step RACH.

[0060] In fifth generation (also known as NR or New Radio) wireless communication systems, a UE can be in one of the following RRC states: RRC IDLE, RRC INACTIVE, and RRC CONNECTED. The RRC states can be further characterized as follows:

[0061] In the RRC_IDLE state, UE-specific discontinuous reception (DRX) can be configured by upper layers (i.e., non-access stratum (NAS)). The UE monitors short messages sent via DCI using the paging RNTI (P-RNTI); monitors the paging channel for CN paging using the 5G-S-TMSI; performs neighbor cell measurements and cell (re)selection; obtains system information and can send an SI request (if configured).

[0062] In the RRC_INACTIVE state, UE-specific DRX can be configured by upper layers or the RRC layer. In this state, the UE stores the UE inactive AS context. The RAN-based notification area is configured by the RRC layer. The UE monitors short messages transmitted via DCI using the P-RNTI; monitors the paging channel for CN paging using 5G-S-TMSI and RAN paging using the fullI-RNTI; performs neighbor cell measurements and cell (re)selection; periodically performs RAN-based notification area updates and when moving outside the configured RAN-based notification area; obtains system information and may send an SI request (if configured).

[0063] In RRC_CONNECTED, the UE stores the AS context. Unicast data is sent to and received from the UE. At lower layers, the UE may be configured with UE-specific DRX. The UE monitors short messages transmitted via DCI using the P-RNTI (if configured); monitors the control channel associated with the shared data channel to determine whether data is scheduled for it; provides channel quality and feedback information; performs neighbor cell measurements and measurement reports; and obtains system information.

[0064] The NR-based 5G or Next Generation Radio Access Network (NG-RAN) consists of NG-RAN nodes, of which the gNB is the NG-RAN node, providing NR user plane and control plane protocol termination to the UE. The gNB is also connected to the 5GC via the NG interface, more specifically, to the Access and Mobility Management Function (AMF) via the NG-C interface, and to the User Plane Function (UPF) via the NG-U interface. In fifth-generation (also known as NR or New Radio) wireless communication systems, UEs can use Distributed Receiving (DRX) in the RRC_IDLE and RRC_INACTIVE states to reduce power consumption. In the RRC_IDLE / RRC_INACTIVE states, the UE wakes up for short periods at regular intervals (i.e., every DRX cycle) to receive paging, SI update notifications, and emergency notifications. Paging messages are transmitted using the PDSCH. If a paging message is sent in the PDSCH, the PDCCH is addressed to the P-RNTI. The P-RNTI is common to all UEs. The UE identity (i.e., the S-TMSI for RRC_IDLE UEs or the I-RNTI for RRC_INACTIVE UEs) is included in the paging message to indicate paging for a specific UE. A paging message can include multiple UE identities to page multiple UEs. The paging message is broadcast over a data channel (i.e., the PDSCH) (i.e., masking the PDCCH with the P-RNTI). SI updates and emergency notifications are included in the DCI, and the PDCCH carrying this DCI is addressed to the P-RNTI. In RRC idle / inactive mode, the UE monitors one paging occasion (PO) during each DRX cycle. In RRC idle / inactive mode, the UE monitors the PO in the initial DL BWP. In RRC_CONNECTED state, the UE monitors one or more POs to receive SI update notifications and emergency notifications. In RRC_CONNECTED state, the UE can monitor any PO during the paging DRX cycle and at least one PO during the SI modification period. In RRC idle / inactive mode, the UE monitors the PO during each DRX cycle in its active DL BWP. The PO is a set of "S" PDCCH monitoring opportunities used for paging, where "S" is the number of SSBs (i.e., synchronization signals and physical broadcast (PBCH) blocks (SSBs) consisting of the primary and secondary synchronization signals (PSS, SSS) and the PBCH) transmitted in a cell. The UE first determines the paging frame (PF) and then determines the PO based on the determined PF. One PF is one radio frame (10 ms).

[0065] Small Data Transfer in Fifth Generation Wireless Communication Systems: Small Data Transfer (SDT) is a procedure that allows data and / or signaling transmission while remaining in the RRC_INACTIVE state (i.e., without transitioning to the RRC_CONNECTED state). SDT is enabled on a radio bearer basis and is initiated by the UE only when less than a configured amount of UL data is pending for transmission on all SDT-enabled radio bearers, the DL RSRP is above a configured threshold, and valid SDT resources are available.

[0066] The SDT procedure is initiated by a transmission over RACH (configured via system information) or over type 1 CG resources (configured via dedicated signaling in RRCRelease). SDT resources can be configured on the initial BWP of RACH and CG. RACH and CG resources for SDT can be configured on one or both of the NUL and SUL carriers. CG resources for SDT are only valid within the cell in which the UE receives RRCRelease and transitions to the RRC_INACTIVE state. For RACH, the network can configure 2-step and / or 4-step RA resources for SDT. When 2-step and 4-step RA resources for SDT are configured, the UE selects the RA type. CFRA is not supported for SDT over RACH.

[0067] Once initiated, the SDT process is:

[0068] - successfully completed after the UE was directed to RRC_IDLE (via RRCRelease), or RRC_INACTIVE (via RRCRelease or RRCReject), or RRC_CONNECTED (via RRCResume or RRCSetup); or

[0069] - Not successfully completed upon cell reselection, expiration of the SDT failure detection timer (also known as T319a), the MAC entity reaching the configured maximum PRACH preamble transmission threshold, the RLC entity reaching the configured maximum retransmission threshold, or expiration of the SDT specific timing alignment timer while the SDT procedure is in progress on the CG and the UE does not receive a response from the network after the initial PUSCH transmission.

[0070] When the SDT procedure is not successfully completed, the UE transitions to RRC_IDLE.

[0071] The initial PUSCH transmission during the SDT procedure includes at least a CCCH message. After initiating the SDT procedure, when the UE transmits a MAC PDU including a CCCH message for the first time, the UE starts the SDT failure detection timer (also known as T319a). When using CG resources for the initial SDT transmission, if the UE does not receive an acknowledgment (dynamic UL grant or DL assignment) from the network before the configured timer expires, the UE may perform an autonomous retransmission of the initial transmission. After the initial PUSCH transmission, subsequent transmissions are handled differently depending on the resource type used to initiate the SDT procedure:

[0072] -When using CG resources, the network may use dynamic grants to schedule subsequent UL transmissions, or they may occur at the following CG resource opportunities. DL transmissions are scheduled using dynamic allocations. The UE may initiate subsequent UL transmissions only after receiving an acknowledgment (dynamic UL grant or DL allocation) of the initial PUSCH transmission from the network. For subsequent UL transmissions, the UE may not initiate retransmissions on CG resources.

[0073] - When using RACH resources, after completing the RA procedure, the network can use dynamic UL grant and DL allocation to schedule subsequent UL and DL transmissions respectively.

[0074] While the SDT procedure is ongoing, if data appears in the buffer of any radio bearer that is not enabled for SDT, the UE initiates transmission of a non-SDT data arrival indication to the network using the UEAssistanceInformation message and, if available, the resumption cause.

[0075] The SDT process on CG resources can only be initiated with a valid UL timing alignment. UL timing alignment is maintained by the UE based on the SDT-specific timing alignment timer configured by the network via dedicated signaling, and for the initial CG-SDT transmission, also by the DL RSRP of the configured number of highest-level SSBs being above the configured RSRP threshold. When the SDT-specific timing alignment timer (i.e., cg-SDT-TimeAlignmentTimer) expires, the CG resources are released while maintaining the CG resource configuration.

[0076] Logical channel restrictions (if any) configured by the network in RRC_CONNECTED state and / or RRCRelease message for SDT-enabled radio bearers are applied by the UE during the SDT procedure.

[0077] When the UE initiates SDT in a cell where the UE receives RRCRelease and transitions to RRC_INACTIVE state, or when the UE initiates SDT in a cell of its Radio Access Network (RAN) Notification Area (RNA), the network may configure the UE to apply ROHC continuity for SDT.

[0078] Reduced Capability UE Support in Fifth Generation Wireless Communication Systems: RedCap UEs have reduced capabilities with the goal of having lower complexity relative to non-RedCap UEs. RedCap UEs must support a maximum UE channel bandwidth of 20 MHz in frequency range 1 (FR1) and a maximum UE channel bandwidth of 100 MHz in frequency range 2 (FR2). RedCap UEs do not support UE features and corresponding capabilities related to UE bandwidths above 20 MHz in FR1 or above 100 MHz in FR2.

[0079] For RedCap UE:

[0080] - The maximum mandatory supported number of Data Radio Bearers (DRBs) is 8; the mandatory supported Packet Data Convergence Protocol (PDCP) Sequence Number (SN) length is 12 bits, while 18 bits is optional; the mandatory supported Radio Link Control (RLC) Acknowledged Mode (AM) SN length is 12 bits, while 18 bits is optional;

[0081] - If 1 Rx branch is supported, it is 1 DL Multiple Input Multiple Output (MIMO) layer, if 2 Rx branches are supported, it is 2 DL MIMO layers. RedCap UE does not support UE features and corresponding capabilities related to more than 2 UE Rx branches and more than 2 DL MIMO layers, as well as UE features and capabilities related to more than 2 UE Tx branches and more than 2 UL MIMO layers;

[0082] - UE features and corresponding capabilities related to CA, MR-DC, Dual Active Protocol Stack (DAPS), Conditional PSCell Addition and Change (CPAC), and Integrated Access and Backhaul (IAB) (i.e., RedCap UE is not expected to act as an IAB node) are not supported by RedCap UEs. Unless otherwise specified, all other feature groups or components of feature groups and capabilities remain applicable to RedCap UEs as for non-RedCap UEs.

[0083] In addition to the initial DL BWP (initialDownlinkBWP), a redcap UE-specific initial DLBWP (initialDownlinkBWP-RedCap) is introduced. In addition to the initial UL BWP (initialUplinkBWP), a redcap UE-specific initial UL BWP (initialUplinkBWP-RedCap) is introduced. initialDownlinkBWP-RedCap and initialUplinkBWP-RedCap are optionally signaled by the gNB in SIB1 in RRC_IDLE.

[0084] At the same time, for small data transmission, the CG resources of SDT are configured for NUL and / or SUL in the RRCRelease message. The SUL CG resources configured for SDT in RRCRelease are used for PUSCH transmission in InitialUplinkBWP. It is assumed that initialUplinkBWP-Redcap is not supported for SUL.

[0085] If the UE is a non-RedCap UE, the NUL CG resources configured for SDT in RRCRelease are used for PUSCH transmission in InitialUplinkBWP. For RedCap UE:

[0086] - If the gNB configures / signals initialUplinkBWP-Redcap for NUL, the NUL CG resources configured for SDT in RRCRelease are used for PUSCH transmission in the initialUplinkBWP-Redcap of NUL. If the gNB does not configure / signal initialUplinkBWP-Redcap for NUL (e.g. in SI), the NUL CG resources configured for SDT in RRCRelease are used for PUSCH transmission in the initialUplinkBWP of NUL.

[0087] When the CG-SDT process is initiated for SDT:

[0088] -For the uplink carrier selected for SDT, if initialUplinkBWP-Redcap is configured, UL transmission during the SDT process is performed through initialUplinkBWP-Redcap. Otherwise, UL transmission during the SDT process is performed through initialUplinkBWP

[0089] - If initialDownlinkBWP-Redcap is configured, DL reception during the SDT process is performed through initialDownlinkBWP-Redcap. Otherwise, DL reception is performed through initialDownlinkBWP.

[0090] Multiple SSBs can be transmitted within the frequency range of a single carrier. The physical cell identifiers (PCIs) of SSBs transmitted at different frequency locations do not necessarily have to be unique; that is, different SSBs in the frequency domain can have different PCIs. However, when an SSB is associated with residual system information (RMSI), it is referred to as a cell-defining SSB (CD-SSB). A cell-defining SSB (CD-SSB) may or may not be located within the initialDownlinkBWP-Redcap. If the initialDownlinkBWP-Redcap is configured and the CD-SSB is not located within the initialDownlinkBWP-Redcap, then A) the UE needs to measure the SSBs on the initialDownlinkBWP for CG resource selection; and B) the UE also needs to monitor the DL on the initialDownlinkBWP-Redcap for PDCCH reception. However, the UE cannot perform A) and B) simultaneously, so the CG-SDT procedure does not operate as expected and requires enhancement.

[0091] [Example 1 - CG-SDT for Redcap-specific initial BWP]

[0092] [Method 1-1]

[0093] Figure 1 An example of a Configuration Grant (CG) SDT process according to an embodiment of the present disclosure is shown.

[0094] In the embodiment of the present disclosure, the operations are as follows:

[0095] The UE is in the RRC_CONNECTED state. In the RRC_CONNECTED state, one or more serving cells can be configured. Serving cells are grouped into one or more Timing Advance Groups (TAGs). The UE maintains separate UL timing for each TAG. The TimeAlignmentTimer is maintained per TAG. The gNB signals the TimeAlignmentTimer value for each TAG in the RRCReconfiguration message. During connection establishment / recovery, the TimeAlignmentTimer value signaled in the system information is used.

[0096] Operation 110: When the UE is in the RRC_CONNECTED state, the UE receives an RRCRelease message with a pending configuration from the gNB. The RRCRelease message indicates or includes the configuration of the CG resources for the SDT. The CG resources for the SDT are configured for the NUL and / or SUL in the RRCRelease message. The RRCRelease message indicates or includes the cg-SDT-TimeAlignmentTimer value.

[0097] Operation 120: The UE enters the RRC_INACTIVE state upon receiving the RRCRelease message with the suspended configuration. When transitioning from RRC_CONNECTED to RRC_INACTIVE, the UE stops all running TimeAlignmentTimers. If the RRCRelease message includes a CG-SDT configuration or a configuration of CG resources for SDT, the UE starts a cg-SDT-TimeAlignmentTimer when transitioning from RRC_CONNECTED to RRC_INACTIVE. The value of this timer is received in the RRCRelease message.

[0098] Operation 130: When in the RRC_INACTIVE state, when data for one or more SDT RBs arrives and the SDT criteria (DL RSRP of the cell is above the RSRP threshold, data available for SDT RB(s) is below the data amount threshold, etc.) are met, the UE selects an UL carrier (NUL or SUL).

[0099] Operation 140: If the RSRP referenced by the downlink path loss is less than rsrp-ThresholdSSB-SUL, then: the UE selects the SUL carrier. Otherwise, the UE selects the NUL carrier.

[0100] * (Cond X) If the UE is a RedCap UE, and if initialDownlinkBWP-Redcap is configured (e.g. signaled by the camped cell in the SI) for the selected UL carrier, and CD-SSB (or non-CD-SSB (NCD-SSB) or both CD-SSB and NCD-SSB) is not located in initialDownlinkBWP-Redcap, and the UE does not have the capability to listen / measure SSBs in initialDownlinkBWP while the CG-SDT procedure is in progress, then:

[0101] **The UE does not select CG-SDT. If the RA-SDT criteria are met, the UE selects RA-SDT. If the RA-SDT criteria are not met, the UE does not initiate an SDT procedure and initiates a non-SDT RRC connection recovery procedure, as in operation 150.

[0102] * Otherwise (i.e., Cond X is not satisfied, i.e., if the UE is not a RedCap UE or if the UE is a RedCap UE and if initialDownlinkBWP-Redcap is not configured for the selected UL carrier; or if the UE is a RedCap UE and if initialDownlinkBWP-Redcap is configured for the selected UL carrier and the CD-SSB (or NCD-SSB or both CD-SSB and NCD-SSB) is not located in the initialDownlinkBWP-RedCap, and the UE has the capability to monitor / measure SSBs in the initialDownlinkBWP while the CG-SDT procedure is ongoing; or if the UE is a RedCap UE and if initialDownlinkBWP-Redcap is configured for the selected UL carrier and the CD-SSB (or NCD-SSB or both CD-SSB and NCD-SSB) is located in the initialDownlinkBWP-Redcap, then:

[0103] **If the CG-SDT criteria are met, the UE selects CG-SDT. If the CG-SDT criteria are not met, then if the RA-SDT criteria are met, the UE selects RA-SDT. If the RA-SDT criteria are not met, the UE does not initiate the SDT procedure and initiates the non-SDTRRC connection recovery procedure.

[0104] [Method 1-2]

[0105] Alternative:

[0106] * (Cond Y) If the UE is a RedCap UE, and the selected UL carrier is SUL, and if initialDownlinkBWP-Redcap is configured for the selected UL carrier (e.g. signaled in SI by the camped cell), and the CD-SSB (or NCD-SSB or both CD-SSB and NCD-SSB) is not in initialDownlinkBWP-Redcap, and the UE does not have the capability to listen / measure SSBs in initialDownlinkBWP while the CG-SDT procedure is in progress, then:

[0107] **UE does not select CG-SDT. If the RA-SDT criteria are met, the UE selects RA-SDT. If the RA-SDT criteria are not met, the UE does not initiate the SDT procedure and initiates the non-SDT RRC connection recovery procedure.

[0108] * Otherwise (i.e., cond Y is not satisfied, i.e., if the selected UL carrier is NUL; if the UE is not a RedCap UE or if the UE is a RedCap UE and the selected UL carrier is SUL, and if initialDownlinkBWP-Redcap is not configured for the selected UL carrier; or if the UE is a RedCap UE and the selected UL carrier is SUL, and if initialDownlinkBWP-Redcap is configured for the selected UL carrier, and the UE has the capability to monitor / measure SSBs in initialDownlinkBWP while the CG-SDT procedure is ongoing; or if the UE is a RedCap UE and the selected UL carrier is SUL, and if initialDownlinkBWP-Redcap is configured for the selected UL carrier and CD-SSB (or NCD-SSB or both CD-SSB and NCD-SSB) are in initialDownlinkBWP-Redcap, then

[0109] **If the CG-SDT criteria are met, the UE selects CG-SDT. If the CG-SDT criteria are not met, then if the RA-SDT criteria are met, the UE selects RA-SDT. If the RA-SDT criteria are not met, the UE does not initiate the SDT procedure and initiates the non-SDTRRC connection recovery procedure.

[0110] When the CG-SDT procedure is initiated for SDT and the UE is a RedCap UE:

[0111] -For the uplink carrier selected for SDT, if initialUplinkBWP-Redcap is configured, UL transmission during the SDT process is performed through initialUplinkBWP-Redcap. Otherwise, UL transmission during the SDT process is performed through initialUplinkBWP.

[0112] - If initialDownlinkBWP-Redcap is configured, DL reception during the SDT process is performed through initialDownlinkBWP-Redcap. Otherwise, DL reception is performed through initialDownlinkBWP.

[0113] Criteria for selecting CG-SDT: If all of the following conditions are met, the CG-SDT criteria are considered met.

[0114] 1> If CG-SDT is configured on the selected UL carrier and the TA configured with grant type 1 resources is valid at the first available CG opportunity; and

[0115] 1> If for each RB that has data available for transmission, configuredGrantType1Allowed (if configured) is configured with the value true for the corresponding logical channel and

[0116] 2> If at least one SSB configured for CG-SDT with SS-RSRP higher than cg-SDT-RSRP-ThresholdSSB is available, then:

[0117] [Method 2-1]

[0118] Figure 2 Another example of a CG-SDT process according to an embodiment of the present disclosure is shown.

[0119] In the embodiment of the present disclosure, the operations are as follows:

[0120] The UE is in the RRC_CONNECTED state. In the RRC_CONNECTED state, one or more serving cells can be configured. Serving cells are grouped into one or more timing advance groups. The UE maintains separate UL timing for each tag. The TimeAlignmentTimer is maintained per tag. The gNB signals the TimeAlignmentTimer value for each tag in the RRCReconfiguration message. During connection establishment / recovery, the TimeAlignmentTimer value signaled in the system information is used.

[0121] Operation 210: When the UE is in the RRC_CONNECTED state, the UE receives an RRCRelease message with a pending configuration from the gNB. The RRCRelease message indicates or includes the configuration of the CG resources for the SDT. The CG resources for the SDT are configured for the NUL and / or SUL in the RRCRelease message. The RRCRelease message indicates or includes the cg-SDT-TimeAlignmentTimer value.

[0122] Operation 220: The UE enters the RRC_INACTIVE state upon receiving an RRCRelease message with a suspended configuration. When transitioning from RRC_CONNECTED to RRC_INACTIVE, the UE stops all running TimeAlignmentTimers. If the RRCRelease message includes a CG-SDT configuration or a configuration of CG resources for SDT, the UE starts a cg-SDT-TimeAlignmentTimer when transitioning from RRC_CONNECTED to RRC_INACTIVE. The value of this timer is received in the RRCRelease message.

[0123] Operation 230: When in the RRC_INACTIVE state, when data of one or more SDT RBs arrives, the SDT criteria are met (DL RSRP of the cell is higher than the RSRP threshold, data available for SDT RBs is lower than the data amount threshold, etc.).

[0124] Operation 240: The UE selects a UL carrier (NUL or SUL). If the RSRP referenced by the downlink path loss is less than rsrp-ThresholdSSB-SUL, then: select the SUL carrier. Otherwise, select the NUL carrier.

[0125] Operation 250: If the CG-SDT criteria are met, the UE selects CG-SDT. If the CG-SDT criteria are not met, then if the RA-SDT criteria are met, the UE selects RA-SDT. If the RA-SDT criteria are not met, the UE does not initiate an SDT procedure, and instead initiates a non-SDT RRC connection recovery procedure.

[0126] Operation 260: If the CG-SDT process is initiated for SDT, then:

[0127] * (A) if the UE is a RedCap UE, and if initialDownlinkBWP-Redcap is configured, and if the CD-SSB (or SSB or CD-SSB and NCD-SSB) is not within the initialDownlinkBWP-Redcap, and the UE has the capability to listen / measure SSB in the initialDownlinkBWP while the CG-SDT procedure is in progress; or

[0128] *(B) If the UE is a RedCap UE, and if initialDownlinkBWP-Redcap is configured, and if CD-SSB (or NCD-SSB) is within initialDownlinkBWP-Redcap, then:

[0129] **UE monitors PDCCH on initialDownlinkBWP-Redcap

[0130] * Otherwise (i.e., neither condition A nor condition B is satisfied), then

[0131] **UE monitors PDCCH on initialDownlinkBWP

[0132] [Method 2-2]

[0133] Alternative:

[0134] If the CG-SDT process is initiated for SDT:

[0135] * If the UE is a RedCap UE, and if initialDownlinkBWP-Redcap is configured, and if CD-SSB (or NCD-SSB) is inside initialDownlinkBWP-Redcap:

[0136] **UE monitors PDCCH on initialDownlinkBWP-Redcap

[0137] *otherwise

[0138] **UE monitors PDCCH on initialDownlinkBWP

[0139] For the uplink carrier selected for SDT, if initialUplinkBWP-Redcap is configured, UL transmission during the SDT process is performed through initialUplinkBWP-Redcap. Otherwise, UL transmission during the SDT process is performed through initialUplinkBWP.

[0140] Criteria for selecting CG-SDT: If all of the following conditions are met, the CG-SDT criteria are considered met.

[0141] 1> If CG-SDT is configured on the selected UL carrier and the TA configured with grant type 1 resources is valid at the first available CG opportunity; and

[0142] 1> If for each RB that has data available for transmission, configuredGrantType1Allowed (if configured) is configured with the value true for the corresponding logical channel and

[0143] 2> If at least one SSB configured for CG-SDT with SS-RSRP higher than cg-SDT-RSRP-ThresholdSSB is available, then:

[0144] [Method 3]

[0145] In the embodiment of the present disclosure, the operations are as follows:

[0146] Step 0: The UE is in the RRC_CONNECTED state. In the RRC_CONNECTED state, one or more serving cells can be configured. Serving cells are grouped into one or more timing advance groups. The UE maintains separate UL timing for each tag. The TimeAlignmentTimer is maintained per tag. The gNB signals the TimeAlignmentTimer value for each tag in the RRCReconfiguration message. During connection establishment / recovery, the TimeAlignmentTimer value signaled in the system information is used.

[0147] Step 1: When the UE is in the RRC_CONNECTED state, the UE receives an RRCRelease message with a pending configuration from the gNB. The RRCRelease message indicates or includes the configuration of the CG resources for the SDT. The CG resources for the SDT are configured for the NUL and / or SUL in the RRCRelease message. The RRCRelease message indicates or includes the cg-SDT-TimeAlignmentTimer value.

[0148] Step 2: The UE enters the RRC_INACTIVE state when it receives the RRCRelease message with the suspended configuration. When transitioning from RRC_CONNECTED to RRC_INACTIVE, the UE stops all running TimeAlignmentTimers. If the RRCRelease message includes the CG-SDT configuration or the configuration of the CG resources of the SDT, the UE starts the cg-SDT-TimeAlignmentTimer when transitioning from RRC_CONNECTED to RRC_INACTIVE. The value of this timer is received in the RRCRelease message.

[0149] Step 3: While in the RRC_INACTIVE state, when data arrives for one or more SDT RBs, and the SDT criteria (cell DL RSRP is above the RSRP threshold, available data for SDT RBs is below the data volume threshold, etc.) are met, the UE selects a UL carrier (NUL or SUL). If the downlink path loss reference RSRP is less than rsrp-ThresholdSSB-SUL, the UE selects the SUL carrier. Otherwise, the NUL carrier is selected.

[0150] *If the CG-SDT criteria are met, the UE selects CG-SDT. If the CG-SDT criteria are not met, then if the RA-SDT criteria are met, the UE selects RA-SDT. If the RA-SDT criteria are not met, the UE does not initiate the SDT procedure and initiates the non-SDT RRC connection recovery procedure.

[0151] *When the CG-SDT procedure is initiated for SDT and the UE is a RedCap UE:

[0152] **For the uplink carrier selected for SDT, if initialUplinkBWP-Redcap is configured, UL transmission during the SDT process is performed through initialUplinkBWP-Redcap. Otherwise, UL transmission during the SDT process (e.g., PUSCH, PUCCH) is performed through initialUplinkBWP.

[0153] **If initialDownlinkBWP-Redcap is configured, DL reception (e.g. PDSCH) during the SDT process is performed through initialDownlinkBWP-Redcap. Otherwise, DL reception is performed through initialDownlinkBWP.

[0154] **If initialDownlinkBWP-Redcap is configured, and CD-SSB (or no SSB, or CD-SSB and NCD-SSB) is not in initialDownlinkBWP-Redcap, then:

[0155] ***UE monitors / measures SSB in initialDownlinkBWP

[0156] ***If the PDCCH monitoring opportunity for monitoring the PDCCH addressed to the C-RNTI / CS-RNTI on the initialDownlinkBWP-Redcap overlaps in time with the SSB in the initialDownlinkBWP, the UE may skip monitoring the PDCCH on the initialDownlinkBWP-Redcap when monitoring / measuring the SSB in the initialDownlinkBWP

[0157] Criteria for selecting CG-SDT: If all the following conditions are met, the CG-SDT criteria are considered to be met.

[0158] 1> If CG-SDT is configured on the selected UL carrier and the TA configured with grant type 1 resources is valid at the first available CG opportunity; and

[0159] 1> If for each RB that has data available for transmission, configuredGrantType1Allowed (if configured) is configured with the value true for the corresponding logical channel and

[0160] 2> If at least one SSB configured for CG-SDT with SS-RSRP higher than cg-SDT-RSRP-ThresholdSSB is available, then:

[0161] In an embodiment, when the UE is in the RRC_CONNECTED state, it can inform the gNB whether it supports NCD-SSB in the RRC_INACTIVE state (or whether it supports NCD-SSB in the RRC_INACTIVE state for SDT, or whether it supports NCD-SSB in the RRC_INACTIVE / Idle state). The UE can notify this using a UE Capability Information message. When the UE is in the RRC_CONNECTED state, the gNB sends an RRCRelease message with a pending configuration to switch the UE to the RRC_INACTIVE state.

[0162] - If initialDownlinkBWP-Redcap is configured for the serving cell (i.e. PCell) and CD-SSB is not in initialDownlinkBWP-Redcap:

[0163] * If the UE supports NCD-SSB in RRC_INACTIVE state (or it supports NCD-SSB in RRC_INACTIVE state for SDT, or it supports NCD-SSB in RRC_INACTIVE / Idle), the gNB may configure NCD-SSB for initialDownlinkBWP-Redcap in the RRCRelease message (or in SI) and include the configuration of CG resources for SDT in the RRCRelease message.

[0164] **In this case, when CG-SDT is initiated, UE can measure / listen to SSB in initialDownlinkBWP-Redcap

[0165] * If the UE does not support NCD-SSB, the gNB does not include the configuration of the CG resources for SDT in the RRCRelease message

[0166] -otherwise:

[0167] * The gNB may include the configuration of the CG resources of the SDT in the RRCRelease message

[0168] * In this case, when CG-SDT is initiated, if initialDownlinkBWP-Redcap is configured, the UE can measure / listen to the SSB in initialDownlinkBWP-Redcap.

[0169] In the above description, “configuration” may mean signaled by the gNB in system information or signaling messages.

[0170] [Example 2 - DCCH and DTCH in MsgB / Msg4]

[0171] Figure 3 An example of MAC PDU and RNTI usage according to an embodiment of the present disclosure is shown.

[0172] According to the latest MAC specification, during the RA-SDT procedure based on 2-step RA and 4-step RA respectively, only CCCH or DCCH MAC PDU can be included in MsgB / Msg4, such as Figure 3 shown.

[0173] Including the DTCH MAC SDU in MsgB / Msg4 can save additional PDCCH transmissions for the gNB and HARQ feedback transmissions for the UE. If inclusion of the DTCH MAC SDU in MsgB / Msg4 is permitted, the DCCH and DTCH can be included together in MsgB / Msg4. For example, during a RA procedure initiated for SDT, the network can send an RRCRelease message along with the DTCH MAC SDU in MsgB / Msg4 in response to MsgA / Msg3 when there is no subsequent UL data and the network has only one DTCH MAC SDU to send. The order in which the DCCH and DTCH are multiplexed in the MsgB / Msg4 MAC PDU needs to be specified to ensure that the RRCRelease message is not processed before the DTCH MAC SDU. If the RRCRelease message is processed before the DTCH MAC SDU, the contents of the DTCH MACSDU will be discarded because the radio bearer (RB) will be suspended while the RRCRelease message is processed.

[0174] In an embodiment of the present disclosure, during a random access procedure initiated for SDT (i.e., RA-SDT), the DCCH and DTCH are not multiplexed together in the Msg4 / MsgB MAC PDU. If the gNB has both DCCH and DTCH MAC SDUs available, the gNB includes the DTCH MAC SDU in the Msg4 / MsgB MAC PDU, which is sent by the gNB in response to reception of Msg4 / MsgA.

[0175] In an embodiment of the present disclosure, during a random access procedure initiated for SDT (i.e., RA-SDT), the DCCH MAC SDU and the DTCH MAC SDU including the RRCRelease message are not multiplexed together in the Msg4 / MsgB MAC PDU. If the gNB has the DCCH MAC SDU and the DTCH MAC SDU including the RRCRelease message available, the gNB includes the DTCH MAC SDU in the Msg4 / MsgB MAC PDU, which is sent by the gNB in response to reception of the Msg4 / MsgA.

[0176] In an embodiment of the present disclosure, during a random access procedure initiated for SDT (i.e., RA-SDT), the DCCH and DTCH may be multiplexed together in a Msg4 / MsgB MAC PDU. If the gNB has both DCCH and DTCH MAC SDUs available, the gNB includes the DTCH MAC SDU in the Msg4 / MsgB MAC PDU, preceding the DCCH MAC SDU, where Msg4 / MsgB is sent by the gNB in response to reception of Msg4 / MsgA.

[0177] In an embodiment of the present disclosure, during a random access procedure initiated for SDT (i.e., RA-SDT), the DCCH and DTCH may be multiplexed together in a Msg4 / MsgB MAC PDU. If the gNB has both a DCCH MAC SDU and a DTCH MAC SDU including an RRCRelease message available, the gNB includes the RRCRelease message in a Msg4 / MsgB MAC PDU before the DCCH MAC SDU includes the DTCH MAC SDU, where Msg4 / MsgB is sent by the gNB in response to reception of Msg4 / MsgA.

[0178] In an embodiment of the present disclosure, in a random access procedure initiated for SDT (ie, RA-SDT), if the UE receives a DCCH MAC SDU and a DTCH MAC SDU in Msg4 / MsgB, the UE should process the DTCH MAC SDU first.

[0179] In an embodiment, when the UE is in the RRC_CONNECTED state, it can inform the gNB whether it supports multiplexing of DCCH and DTCH in the Msg4 / MsgB MAC PDU. Only if the UE indicates support, the gNB can multiplex DCCH and DTCH in the Msg4 / MsgB MAC PDU during SDT.

[0180] Figure 4 is a block diagram of a terminal according to an embodiment of the present disclosure.

[0181] refer to Figure 4 , the terminal includes a transceiver 410, a controller 420, and a memory 430. The controller 420 may refer to a circuit, an application specific integrated circuit (ASIC), or at least one processor. The transceiver 410, the controller 420, and the memory 430 are configured to execute a diagram (e.g., Figures 1 to 3) or described above. Although transceiver 410, controller 420, and memory 430 are shown as separate entities, they may be implemented as a single entity, such as a single chip. Alternatively, transceiver 410, controller 420, and memory 430 may be electrically connected or coupled to each other.

[0182] The transceiver 410 may transmit signals to and receive signals from other network entities (eg, a base station or another terminal).

[0183] The controller 420 may control the UE to perform the function according to one of the above embodiments.

[0184] In an embodiment, the operation of the terminal can be implemented using a memory 430 storing corresponding program codes. Specifically, the terminal can be equipped with a memory 430 to store program codes for implementing desired operations. To perform the desired operations, the controller 420 can read and execute the program codes stored in the memory 430 using a processor or a central processing unit (CPU).

[0185] Figure 5 is a block diagram of a base station according to an embodiment of the present disclosure.

[0186] refer to Figure 5 , the base station includes a transceiver 510, a controller 520 and a memory 530. The transceiver 510, the controller 520 and the memory 530 are configured to execute, for example Figures 1 to 3 The operation of a network (e.g., a gNB) as shown in the accompanying drawings or described above is described. Although transceiver 510, controller 520, and memory 530 are shown as separate entities, they may be implemented as a single entity, such as a single chip. Transceiver 510, controller 520, and memory 530 may be electrically connected or coupled to each other.

[0187] The transceiver 510 can send and receive signals to and from other network entities (e.g., terminals). The controller 520 can control the base station to perform functions according to one of the above-described embodiments. The controller 520 can be a circuit, an ASIC, or at least one processor. In embodiments, base station operations can be implemented using a memory 530 storing corresponding program code. Specifically, the base station can be equipped with the memory 530 to store program code for implementing desired operations. To perform desired operations, the controller 520 can read and execute the program code stored in the memory 530 using a processor or CPU.

[0188] While the present disclosure has been shown and described with reference to various embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made without departing from the spirit and scope of the present disclosure as defined by the appended claims and their equivalents.

[0189] As described above, the embodiments disclosed in the specification and the drawings are only used to present specific examples to easily explain the content of the present disclosure and help understanding, but are not intended to limit the scope of the present disclosure. Therefore, in addition to the embodiments disclosed herein, the scope of the present disclosure should be analyzed to include all changes or modifications derived based on the technical concept of the present disclosure.

Claims

1. A method performed by a terminal in a wireless communication system, the method comprising: receiving a radio resource control (RRC) release message including a suspended configuration from a base station, the RRC release message including information about a configuration grant (CG) resource for small data transmission (SDT); identifying an uplink carrier for the SDT data based on satisfying the SDT criteria; An SDT process for identifying SDT data in a CG-SDT process and a random access (RA)-SDT process; as well as The SDT data is sent to the base station on the uplink carrier according to the SDT procedure.

2. The method according to claim 1, wherein The SDT identification process also includes: When the terminal is a reduced capability terminal, a first initial downlink bandwidth part (BWP) of the reduced capability terminal is configured for an uplink carrier, and when the CG-SDT procedure is in progress, the terminal does not have the ability to monitor the synchronization signal and the physical broadcast block (SSB) in the second initial downlink BWP, the RA-SDT procedure is selected based on satisfying the RA-SDT criteria.

3. The method according to claim 2, wherein: In case the cell-defined SSB (CD-SSB) is not located in the first initial downlink BWP of the reduced capability terminal, the RA-SDT procedure is selected.

4. The method according to claim 2, wherein: In case the RA-SDT criteria are not met, the SDT process is not initiated and SDT data is sent according to the non-SDT RRC recovery process.

5. The method according to claim 1, wherein The SDT identification process also includes: When the terminal is not a reduced capability terminal, the first initial downlink BWP of the reduced capability terminal is not configured for the uplink carrier, or when the CG-SDT process is in progress, the terminal has the ability to monitor SSB in the second initial downlink BWP, the CG-SDT process is selected based on satisfying the CG-SDT criteria.

6. The method according to claim 5, wherein: In case the CD-SSB is located in the first initial downlink BWP of the reduced capability terminal, the CG-SDT procedure is selected.

7. The method according to claim 5, wherein: In the case where the CG-SDT criteria are not satisfied, the RA-SDT process is selected based on satisfying the RA-SDT criteria, and In the case that the RA-SDT criteria are not met, the SDT process is not initiated, and the SDT data is sent according to the non-SDT RRC recovery process.

8. The method according to claim 1, wherein The uplink carrier is either a normal uplink (NUL) carrier or a supplementary uplink (SUL) carrier.

9. A terminal in a wireless communication system, the terminal comprising: transceiver; as well as A controller is coupled to the transceiver and is configured to: receiving a radio resource control (RRC) release message including a suspended configuration from a base station, the RRC release message including information about a configuration grant (CG) resource for a small data transmission (SDT), Based on satisfying the SDT criteria, identifying the uplink carrier of the SDT data, Identify the SDT process of SDT data in the CG-SDT process and the random access (RA)-SDT process, and The SDT data is sent to the base station on the uplink carrier according to the SDT procedure.

10. The terminal according to claim 9, wherein: The uplink carrier is either a NUL carrier or a SUL carrier, and The controller is further configured as follows: When the terminal is a reduced capability terminal, a first initial downlink bandwidth part (BWP) of the reduced capability terminal is configured for an uplink carrier, and when the CG-SDT procedure is in progress, the terminal does not have the ability to monitor the synchronization signal and the physical broadcast block (SSB) in the second initial downlink BWP, the RA-SDT procedure is selected based on satisfying the RA-SDT criteria. The terminal according to claim 10 , wherein: In case the cell-defined SSB (CD-SSB) is not located in the first initial downlink BWP of the reduced capability terminal, the RA-SDT procedure is selected. The terminal according to claim 10 , wherein: In case the RA-SDT criteria are not met, the SDT process is not initiated and SDT data is sent according to the non-SDT RRC recovery process.

13. The terminal according to claim 9, wherein: The controller is also configured to: When the terminal is not a reduced capability terminal, the first initial downlink BWP of the reduced capability terminal is not configured for the uplink carrier, or when the CG-SDT process is in progress, the terminal has the ability to monitor SSB in the second initial downlink BWP, the CG-SDT process is selected based on satisfying the CG-SDT criteria. The terminal according to claim 13 , wherein: In case the CD-SSB is located in the first initial downlink BWP of the reduced capability terminal, the CG-SDT procedure is selected. The terminal according to claim 13 , wherein: In the case where the CG-SDT criteria are not satisfied, the RA-SDT process is selected based on satisfying the RA-SDT criteria, and In the case that the RA-SDT criteria are not met, the SDT process is not initiated, and the SDT data is sent according to the non-SDT RRC recovery process.

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