Method and apparatus for optimizing random access in wireless communication system

Abstract

The present disclosure relates to a 5th-Generation (5G) or 6th-Generation (6G) communication system for supporting higher data transmission rates. More specifically, the present disclosure relates to a method performed by a user equipment (UE) in a wireless communication system, comprising receiving a radio resource control (RRC) release message including first information for small data transmission (SDT) configuration from a base station, transmitting small data to the base station based on the first information, and transmitting a random access (RA) report including SDT information to the base station.

Description

Technical Field

[0001] The present disclosure relates generally to mobile communication systems, and more particularly, to a method and apparatus for optimizing random access (RA) associated with small data transmission (SDT). Background Art

[0002] The fifth generation (5G) mobile communication technology defines a wide frequency band, making high transmission rates and new services possible, and can be realized not only in frequency bands below 6 gigahertz (GHz) such as 3.5 GHz, but also in frequency bands above 6 GHz called millimeter waves (mmWave) including 28 GHz and 39 GHz. In addition, the sixth generation (6G) mobile communication technology (called "super 5G system") has been considered to be implemented in terahertz (THz) bands such as 95 GHz to 3 THz bands to achieve a transmission rate fifty times faster than 5G mobile communication technology and an ultra-low latency one-tenth of 5G mobile communication technology.

[0003] At the beginning of the development of 5G mobile communication technology, in order to support services and meet performance requirements related to enhanced mobile broadband (eMBB), ultra-reliable low latency communication (URLLC) and massive machine type communication (mMTC), there is ongoing standardization on the following items: beamforming and massive multiple-input multiple-output (MIMO) for mitigating radio wave path loss and increasing radio wave transmission distance in millimeter wave (mmWave), parameter sets supporting dynamic operations for efficient utilization of millimeter wave resources and time slot formats (such as operating multiple subcarrier spacings), initial access technology for supporting multi-beam transmission and broadband, definition and operation of bandwidth parts (BWP), new channel coding methods (such as low-density parity check (LDPC) codes for large-scale data transmission and polarization codes for highly reliable transmission of control information), L2 preprocessing, and network slicing for providing dedicated networks dedicated to specific services.

[0004] Currently, in view of the services to be supported by 5G mobile communication technology, discussions are ongoing on improvements and performance enhancements of initial 5G mobile communication technology, and there is already physical layer standardization on technologies such as: Vehicle-to-Everything (V2X), for assisting driving determination of autonomous vehicles based on information about the location and status of the vehicle sent by the vehicle and for enhancing user convenience; New Radio Unlicensed (NR-U), designed to comply with various regulatory-related requirements of system operation in unlicensed bands; NR User Equipment (NR UE) power saving; Non-Terrestrial Network (NTN), which is UE satellite direct communication for providing coverage in areas where communication with terrestrial networks is unavailable; and positioning.

[0005] In addition, there is ongoing standardization in the air interface architecture / protocol on technologies such as: Industrial Internet of Things (IIoT) for supporting new services through interworking and convergence with other industries, Integrated Access and Backhaul (IAB) for providing nodes for network service area expansion by supporting wireless backhaul links and access links in an integrated manner, mobility enhancements including conditional switching and dual active protocol stack (DAPS) switching, and two-step RA channel (RACH) for simplifying the RA process. There is also ongoing standardization on 5G service-based architecture or service-based interface for combining network function virtualization (NFV) and software defined network (SDN) technologies and system architecture / service for mobile edge computing (MEC) for receiving services based on UE location.

[0006] With the commercialization of 5G mobile communication systems, the already exponentially growing number of connected devices will be connected to the communication network, and it is accordingly expected that enhanced functions and performance of the 5G mobile communication system and integrated operations of the connected devices will be necessary. To this end, new research related to extended reality (XR) is arranged to effectively support augmented reality (AR), virtual reality (VR), mixed reality (MR), etc., improve 5G performance and reduce complexity by utilizing artificial intelligence (AI) and machine learning (ML), AI service support, meta-service support, and drone communication.

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

[0008] In a wireless communication system, when a UE does not transmit data for a certain period of time, the UE is converted into an idle or inactive state. When small-sized data is transmitted intermittently, the UE is likely to transmit data in the idle or inactive state.

[0009] Therefore, there is a need in the art for an operation procedure for reconfiguring bearers and control connections. When the size of data sent by a UE is small (ie, in SDT), the efficiency of the operation procedure for data transmission in an idle or inactive state can be improved. Summary of the invention

[0010] Technical issues

[0011] Accordingly, the present disclosure provides embodiments designed to address at least the problems and / or disadvantages described above and to provide at least the advantages described below.

[0012] An aspect of the present disclosure is to provide a method and apparatus for reporting a RACH-based SDT process and SDT-related information in a wireless communication system.

[0013] Another aspect of the present disclosure is to provide a UE that can efficiently perform SDT by enabling data and signaling transmission while maintaining an RRC_INACTIVE state.

[0014] Another aspect of the present disclosure is to provide a UE, which can collect SDT-related information and report it to a base station, thereby enabling the base station to effectively perform scheduling.

[0015] Solution to the problem

[0016] According to one aspect of the present disclosure, a method performed by a UE in a wireless communication system includes: receiving a radio resource control (RRC) release message including first information for SDT configuration from a base station, sending small data to the base station based on the first information, and sending an RA report including SDT information to the base station.

[0017] According to one aspect of the present disclosure, a method performed by a base station in a wireless communication system includes sending an RRC release message including first information for SDT configuration to a UE, receiving small data from the UE based on the first information, and receiving an RA report including SDT information from the UE.

[0018] According to one aspect of the present disclosure, a UE in a wireless communication system includes: a transceiver configured to send or receive a signal; and at least one processor configured to receive an RRC release message including first information for SDT configuration from a base station, send small data to the base station based on the first information, and send an RA report including SDT information to the base station.

[0019] According to one aspect of the present disclosure, a base station in a wireless communication system includes: a transceiver configured to send or receive a signal; and at least one processor configured to send an RRC release message including first information for SDT configuration to a UE, receive small data from the UE based on the first information, and receive an RA report including SDT information from the UE.

[0020] Advantageous Effects of the Invention

[0021] Advantages and features of the present disclosure and modes for achieving the same will be apparent by referring to the embodiments as described in detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The above and other aspects, features and advantages of certain embodiments of the present disclosure will become more apparent through the following description in conjunction with the accompanying drawings, in which:

[0023] Figure 1A shows the structure of a next generation mobile communication system according to an embodiment;

[0024] Figure 1B shows the RA process according to an embodiment;

[0025] Figure 1C A two-step RA process according to an embodiment is shown;

[0026] Figure 1D A process for performing RACH reporting according to an embodiment is shown;

[0027] Figure 1E Showing an SDT process for sending small data according to an embodiment;

[0028] Figure 1F shows a process of collecting and reporting SDT related information according to an embodiment;

[0029] Figure 1G shows time information related to SDT according to an embodiment;

[0030] Figure 1H illustrates a UE process for collecting and reporting SDT related information according to an embodiment;

[0031] Fig. 1I illustrates a base station process for collecting and reporting SDT related information according to an embodiment;

[0032] Figure 1J is a block diagram showing an internal structure of a UE according to an embodiment; and

[0033] Figure 1K is a block diagram showing the structure of an NR base station according to an embodiment. DETAILED DESCRIPTION

[0034] Hereinafter, an electronic device and a method thereof are described with reference to the accompanying drawings. The term "user" used herein may refer to a person using an electronic device or a device using an electronic device such as an AI electronic device. For the sake of clarity and conciseness, a detailed description of known functions and / or configurations will be omitted.

[0035] In the drawings, some elements may be exaggerated, omitted or schematically illustrated, the size of each element does not entirely reflect the actual size, and the same reference numerals are provided to the same or corresponding elements.

[0036] By referring to the embodiments described in detail below in conjunction with the accompanying drawings, the advantages and features of the present disclosure and the modes for achieving them will be apparent. However, the present disclosure is not limited to the embodiments set forth below, but can be implemented in various different forms. The following embodiments are provided only to fully disclose the present disclosure and inform those skilled in the art of the scope of the present disclosure. Throughout the specification, the same or similar reference numerals represent the same or similar elements.

[0037] As used herein, "unit" refers to a software element or a hardware element that performs a predetermined function, such as a field programmable gate array (FPGA) or an application specific integrated circuit (ASIC). However, the unit does not always have a meaning limited to software or hardware, and can be constructed to be stored in an addressable storage medium or to perform one or more processors. Therefore, the unit includes, for example, software elements, object-oriented software elements, class elements or task elements, processes, functions, attributes, processes, subroutines, program code segments, drivers, firmware, microcodes, circuits, data, databases, data structures, tables, arrays and parameters. The elements and functions provided by the unit can be combined into a smaller number of elements or units, or divided into a larger number of elements or units. In addition, elements and units can be implemented as one or more central processing units (CPUs) in a reproduction device or a secure multimedia card.

[0038] Although the present disclosure will be described based on a long term evolution (LTE) system, the present disclosure may also be applied to other mobile communication systems, such as an NR system as a next generation mobile communication system. Herein, an evolved Node B (eNB) in LTE corresponds to a gNB in ​​NR, and a mobile management entity (MME) in LTE corresponds to an access and mobility management function (AMF) in NR.

[0039] Figure 1A A structure of a next generation mobile communication system according to an embodiment is shown.

[0040] refer to Figure 1A, the radio access network of the NR system consists of the next generation base station (new radio node B, hereinafter referred to as gNB) 1a-10 and AMF (new radio core network) 1a-05. NR UE or terminal 1a-15 accesses the external network through gNB 1a-10 and AMF1a-05.

[0041] exist Figure 1A In the present invention, the gNB corresponds to the eNB of the existing LTE system. The gNB is connected to the NR UE 1a-15 through the radio channel 1a-20 and can provide services that are superior to those of the existing eNB 1a-30.

[0042] In the next generation mobile communication system, since all user services are served through a shared channel, a device for scheduling by collecting status information such as the buffer status of the UE, the available transmission power status, the channel status, etc. is required, and gNB 1a-10 is responsible for the scheduling. One gNB usually controls multiple cells. Compared with the existing LTE, a bandwidth greater than or equal to the existing maximum bandwidth can be applied to achieve ultra-high-speed data transmission, and additional beamforming technology can be grafted by using orthogonal frequency division multiplexing (OFDM) as a radio access technology. In addition, an adaptive modulation & coding (AMC) scheme is applied to determine the modulation scheme and channel coding rate according to the channel status of the UE.

[0043] AMF 1a-05 performs functions such as mobility support, bearer configuration, quality of service (QoS) configuration, etc., guides various control functions of UE and mobility management functions, and is connected to multiple base stations. In addition, the next-generation mobile communication system can be linked with the existing LTE system, and AMF 1a-05 is connected to MME 1a-25 through a network interface. MME 1a-25 is connected to the existing eNB 1a-30. A UE supporting LTE-NR dual connectivity can send and receive data while maintaining a connection with eNB 1a-30 and gNB 1a-10.

[0044] Figure 1B An RA procedure according to an embodiment is shown.

[0045] RA is performed when uplink synchronization is performed or data is sent to the network. More specifically, RA can be performed when the UE switches from standby mode to connected mode, when RRC re-establishment is performed, when handover is performed, and when uplink and downlink data start.

[0046] When a dedicated preamble is received from the base station 1b-10, the UE 1b-05 transmits a preamble by applying the preamble. Otherwise, the UE 1b-05 selects one of the two preamble groups (group A and group B) and selects the preamble belonging to the selected group. When the channel quality state is better than a specific threshold and the size of message 3 (msg3) is greater than a specific threshold, the preamble belonging to group B is selected; otherwise, the preamble belonging to group A is selected.

[0047] In step 1b-15, a preamble is transmitted from UE 1b-05 to eNB 1b-10 in the nth subframe. In step 1b-20, UE 1b-05 starts a RA response (RAR) window from the n+3th subframe and monitors whether the RAR is transmitted within the window time interval. RAR scheduling information is indicated by a RA radio network temporary identifier (RA-RNTI) of a physical downlink control channel (PDCCH). The RA-RNTI is induced by using a radio resource position on a time axis and a frequency axis for transmitting a preamble.

[0048] The RAR includes a timing advance command, a UL grant, and a temporary C-RNTI. If the RAR is successfully received within the RAR window, in step 1b-25, the UE 1b-05 sends msg3 to the eNB 1b-10 by using the UL grant information included in the RAR.

[0049] According to the purpose of RA, msg3 includes other information. Table 1 below is an example of the information included in msg3.

[0050]

Table 1

[0051]

[0052] If RAR is received in the nth subframe, msg3 is transmitted in the n+6th subframe. Hybrid Automatic Request (HARQ) is applied from msg3.

[0053] In step 1b-30, after sending msg3, UE 1b-05 drives a specific timer and monitors a contention resolution (CR) message (msg4) until the timer expires. In addition to the CR MAC CE, the CR message includes an RRC connection establishment or RRC connection reestablishment message depending on the purpose of the RA.

[0054] Figure 1C A two-step RA process according to an embodiment is shown.

[0055] The two-step RA process includes msgA1c-15 sent by UE 1c-05 in the uplink and msgB 1c-20 sent by base station 1c-10 in the downlink. Conceptually, msgA has the contents of msg1 (i.e., preamble) and msg3 in the traditional RA process and the scheduling information of msgB, and msgB has the contents of msg2 (i.e., RAR) and msg4 in the traditional RA process. The information included in the traditional msg3 is listed in Table 1 above. Depending on the purpose of the RA, the information stored in msg3 is different, and similarly, the information stored in msgA will be different depending on the purpose of the two-step RA. The information stored in the traditional msg2 consists of the RA preamble ID (RAPID), timing advance (TA) command, UL authorization, and temporary C-RNTI.

[0056] If the two-step RA process is deemed to have failed based on predetermined conditions, it can be converted to Figure 1B The predetermined condition is, for example, when two-step RA fails for more than a configured number of times, or when a message indicating switching to four-step RA (e.g., fallback RAR) is received from the network. The predetermined configuration information is provided to the UE via system information broadcast by the network. The system information is always stored in a periodically broadcast master information block (MIB) or system information block 1 (SIB1).

[0057] Figure 1D A process of performing RACH reporting according to an embodiment is shown.

[0058] RA reporting is a reporting mechanism for reporting information related to the RA process performed by the UE to the network. In addition to RA triggered for the purpose of requesting system information, successfully completed RA processes are subject to reporting. Up to eight RA report entries storing information related to each RA process can be included in the RA report. In the next generation mobile communication system NR, from Rel-17, RA reporting has been confirmed to record and report information related to 2-step RA and 4-step RA.

[0059] UE 1d-05 performs the RA process to the base station (gNB) 1d-10.

[0060] In step 1d-15, UE 1d-05 stores predetermined information related to the successfully completed RA process. The predetermined information is as follows.

[0061] The cell ID (Cell Global Identity (CGI), Physical Cell ID (PCI)) and center frequency information of the RA are performed.

[0062] Perform RA purposes such as access, beam failure recovery, handover, or uplink synchronization.

[0063] The index value of the synchronization signal block (SSB) or channel state information reference signal (CSI-RS) for which RA is attempted and the number of transmissions of the preamble code in the SSB or CSI-RS.

[0064] Whether the signal quality of SSB is greater than the threshold (dlRSRPAboveThreshold) and whether contention has occurred during RA (contentionDetected).

[0065] Frequency location and bandwidth information of RA radio resources.

[0066] Subcarrier spacing information used in the BWP of RA radio resources.

[0067] The absolute frequency position information of the reference resource block (ie, common RB0).

[0068] Information related to msg1 or msgA transmission, such as the start time of the frequency used for msg1 or msgA transmission, the subcarrier spacing information used for msg1 or msgA transmission, and the FDM information used for msg1 or msgA transmission.

[0069] The aforementioned information is stored and reported to the base station according to the following ASN.1 structure: A successfully completed RA procedure is stored and reported in the RA-Report IE, and up to 8 RA reports can be stored in the RA-ReportList IE, as shown in Table 2 below.

[0070] Information about multiple RA attempts in chronological order is stored in one RA-Report IE (Per-RAInfoList IE), also shown in Table 2 below.

[0071] In the PerRAInfo IE stored in the Per-RAInfoList, the above-mentioned information is stored for each SSB or CSI-RS used for the RA attempt.

[0072] Information about each RA attempt, contentionDetected and dlRSRPAboveThreshold is stored in the PerRAAttemptInfo IE in the PerRAAttemptInfoList.

[0073]

Table 2

[0074]

[0075]

[0076] In step 1d-20, UE 1d-05 in standby mode or inactive mode sends an RRCSetupRequest or RRCResumeRequest message to base station 1d-10 to switch to connected mode.

[0077] In step 1d-25, the base station 1d-10 sends an RRCSetup message or an RRCResume message to UE 1d-05, and upon receiving the message, UE 1d-05 switches to connected mode.

[0078] In step 1d-30, UE 1d-05 sends an RRCSetupComplete message or an RRCResumeComplete message to base station 1d-10.

[0079] In step 1d-35, the base station 1d-10 requests UE 1d-05 to report the information by using a UEInformationRequest message.

[0080] In step 1d-40, the UE 1d-05 receiving the request sends a UEInformationResponse message including the stored information to the gNB 1d-10. The RA report information reported to the base station is deleted. Even if the stored RA report is not reported to the base station, the UE can delete the report after a specific period of time.

[0081] Figure 1E An SDT procedure for transmitting small data according to an embodiment is shown.

[0082] In step 1e-15, UE 1e-05 sends its capability information to gNB 1e-10. The capability information may include an indicator indicating whether UE 1e-05 supports RA reporting and SDT.

[0083] In step 1e-20, the gNB 1e-10 sends a RRCRelease message including a suspendConfig IE to the UE 1e-05 to switch the UE 1e-05 to the inactive mode. The suspendConfig IE includes configuration information related to the inactive mode.

[0084] gNB 1e-10 can configure SDT for UE 1e-05 switched to inactive mode. In this case, the RRCRelease message includes SDT-Config IE, which includes configuration information related to SDT. Table 3 below shows the information stored in the IE.

[0085]

Table 3

[0086]

[0087] Through SDT, a data radio bearer (DRB) capable of transmitting data is configured, and whether SRB2 is allowed to be used for SDT may be configured. In addition, MAC and PHY related configuration information and supplementary related configuration information may be considered.

[0088] In step 1e-25, UE 1e-05 having received the RRCRelease message switches to an inactive mode.

[0089] In step 1e-30, UE 1e-05 receives system information from gNB 1e-10, and gNB 1e-10 broadcasts configuration information related to SDT through the system information. Table 4 below shows the configuration information broadcast through the system information.

[0090]

Table 4

[0091]

[0092] The sdt-RSRP-Threshold field is used to indicate a received signal strength reference signal received power (RSRP) threshold to be considered in order for the UE to determine whether to perform the SDT process.

[0093] The sdt-LogicalChannelSR-DelayTimer field is used to indicate the value of the LogicalChannelSR-DelayTimer applied to the logical channel during the SDT period.

[0094] The sdt-DataVolumeThreshold field is used to indicate the threshold of the data size to be considered so that the UE determines whether to perform the SDT process.

[0095] The t319a field is used to indicate the value of the T319a timer. When the RRCResumeRequest message is sent for SDT purposes, the T319a timer is driven, and if the SDT is not completed until the timer expires, the SDT process is considered to have failed. Specifically, the timer is stopped when a RRCResume, RRCsetup, RRCRelease, or RRCReject message is received, and when the SDT is considered to have failed (even before the timer expires) according to predetermined conditions.

[0096] The system information may include RACH configuration information that may be used for SDT.

[0097] In step 1e-35, UE 1e-05 compares the received signal strength and the size of data to be transmitted with the sdt-RSRP-Threshold field value and the sdt-DataVolumeThreshold field value, respectively, and determines to transmit the data through the SDT procedure.

[0098] In addition, the UE initiates a four-step or two-step RA procedure according to conventional rules.

[0099] In step 1e-40, if the four-step RA process is triggered, the UE 1e-05 stores the small data together with the RRCResumeRequest message in the Msg3 message, or if the two-step RA process is triggered, the small data is stored together with the RRCResumeRequest message in MsgA, and the UE 1e-05 sends the small data to the gNB 1e-10.

[0100] In step 1e-45, gNB 1e-10 may additionally schedule UE 1e-05.

[0101] In step 1e-50, UE 1e-05 can send small data to gNB 1e-10 according to scheduling.

[0102] During the SDT process, data corresponding to a radio bearer for which SDT data transmission is not allowed may be generated in the UE. In this case, in step 1e-55, the UE 1e-05 may send a UEAssistanceInformation message including an indicator (non-SDT-DataIndication field) indicating this situation to the gNB 1e-10. The indicator may include a recovery cause value including cause information for recovery, such as emergency, high priority access, and mobile terminated (MT) access. In the TS38.331 standard document, the recovery cause is shown in Table 5 below.

[0103]

Table 5

[0104]

[0105] Upon receiving the indicator, the base station may switch the UE to connected mode to receive data.

[0106] In step 1e-60, when the SDT transmission is completed, the base station 1e-10 may switch the UE 1e-05 back to the inactive mode by using the RRCRelease message including the suspendConfigIE.

[0107] Depending on the situation, the base station 1e-10 may send RRCRelease, RRCsetup, RRCRelease, and RRCReject messages that do not include the suspendConfig IE to the UE 1e-05 to switch the UE 1e-05 to the standby mode or the connected mode.

[0108] In step 1e-65, the UE 1e-05 having received the RRCRelease message including the suspendConfigIE switches to the inactive mode.

[0109] Figure 1F A process of collecting and reporting SDT-related information according to an embodiment is shown.

[0110] In step 1f-15, UE 1f-05 sends its capability information to gNB 1f-10. The capability information may include an indicator indicating whether UE 1f-05 supports RA reporting and SDT. In addition, the capability information may include an indicator indicating that information related to SDT can be recorded and reported through RA reporting.

[0111] In step 1f-20, gNB 1f-10 sends a RRCRelease message including a suspendConfig IE to UE 1f-05 to switch UE 1f-05 to the inactive mode. The suspendConfig IE includes configuration information related to the inactive mode.

[0112] The gNB 1f-10 may configure SDT for the UE 1f-05 switched to inactive mode. In this case, the RRCRelease message includes an SDT-Config IE including configuration information related to SDT. In addition, the base station may configure an operation of collecting SDT-related information through the RRCRelease message and reporting it to the UE through an RA report. To this end, an indicator indicating the collection and storage of SDT-related information and reporting the SDT-related information through an RA report is included in the RRCRelease message.

[0113] In addition to the indicator, frequency list information or cell / tracking area ID information for collecting SDT-related information can also be provided. The gNB 1f-10 can perform configuration through LoggedMeasurementConfiguration or RRCReconfiguration message.

[0114] In step 1f-25, UE 1f-05 that has received the RRCRelease message switches to inactive mode (RRC_inactive).

[0115] In step 1f-30, UE 1f-05 receives system information from a predetermined gNB 1f-10. gNB 1f-10 may broadcast configuration information related to SDT through the system information.

[0116] In step 1f-35, UE 1f-05 compares the received signal strength and the size of the data to be sent with the sdt-RSRP-Threshold field value and the sdt-DataVolumeThreshold field value respectively, and determines to send the data through the SDT process.

[0117] In step 1f-37, UE 1f-05 triggers a four-step or two-step RA process according to conventional rules. In this case, UE 1f-05 can collect and store information related to the SDT operation as the content of the RA report.

[0118] In step 1f-40, if the four-step RA process is triggered, the UE 1f-05 stores the small data together with the RRCResumeRequest message in the Msg3 message, or if the two-step RA process is triggered, the UE 1f-05 stores the small data together with the RRCResumeRequest message in MsgA, and the UE 1f-05 sends the small data to gNB 1f-10.

[0119] In step 1f-45, gNB 1f-10 may additionally schedule UE 1f-05.

[0120] In step 1f-50, UE 1f-05 can send UL small data according to the scheduling.

[0121] During the SDT process, data corresponding to the radio bearers for which SDT data transmission is not allowed may be generated in the UE. In this case, in step 1f-55, the UE 1f-05 may send a UEAssistanceInformation message including an indicator indicating this situation to the gNB 1f-10 1f-55. Upon receiving the indicator, the gNB 1f-10 may switch the UE 1f-05 to a connected mode to receive data.

[0122] In step 1f-60, when the SDT transmission is completed, gNB 1f-10 may switch UE 1f-05 back to inactive mode by using an RRCRelease message including the suspendConfigIE.

[0123] Depending on the situation, the gNB 1f-10 may send RRCRelease, RRCsetup, RRCRelease, and RRCReject messages without including the suspendConfigIE to the UE to switch the UE to standby mode or connected mode.

[0124] During the SDT procedure, the UE stores SDT related information in the RA report as follows.

[0125] A new code point for the raPurpose field, as shown in Table 6 below, indicates a RA triggered for SDT. The raPurpose field may be stored for each entry of a RA report, and the field is used to indicate the purpose of triggering the RA (see capture below). A new code point indicating that the RA is triggered for SDT operation may be added to this field. Alternatively, instead of a new code point, a new indicator field indicating a RA triggered for SDT may be included.

[0126]

Table 6

[0127]

[0128] SDT configuration information stored and provided in RRCRelease. For example, DRB ID information for SDT configuration, indicator indicating whether SRB2 is configured for SDT. When the network reconfigures SDT for the UE later, the configuration information can be used for optimization.

[0129] SDT configuration information stored and provided in the system information. For example, the sdt-RSRP-Threshold field, the sdt-LogicalChannelSR-DelayTimer field, and the sdt-DataVolumeThreshold field. This information can be used by the network to adjust the frequency of triggering SDT operations within the service area, or to optimize the SDT success rate or SDT delay performance.

[0130] The measured RSRP value that triggers the SDT operation and the actual data size value that triggers the SDT operation. When the network adjusts the configuration values ​​of the sdt-RSRP-Threshold field and the sdt-DataVolumeThreshold field, these two types of information can be referred to.

[0131] Indicator indicating whether the base station where the UE has attempted RA supports SDT. Indicator information indicating whether the cell where the RA is attempted can support SDT may be included in an RA report entry for one RA.

[0132] Indicator indicating whether SDT is performed in the normal uplink (NUL) or the supplementary uplink (SUL). SDT can be performed in the NUL or the SUL. Therefore, it is necessary to inform the network on which uplink SDT is performed.

[0133] An indicator indicating whether data corresponding to a radio bearer not configured for SDT has occurred during SDT. Alternatively, an indicator indicating whether transmission of a UEAssistanceInformation message including a nonSDT-DataIndication field has been triggered. In this case, the ID information of the radio bearer included in the nonSDT-DataIndication field, the data size, and the recovery cause value may be included together in the RA report. This information may be utilized by the network to determine the DRB to be configured for SDT.

[0134] An indicator indicating whether the UE has switched to connected mode after SDT operation. That is, whether the UE receives RRCesume or RRCSetup message during the SDT process.

[0135] An indicator indicating whether the UE has switched to standby mode after SDT operation. That is, whether the UE receives a RRCRelease message without the suspendConfig IE during the SDT process.

[0136] Whether the UE receives an RRCReject message after the SDT operation. In this case, the waitTime information value included in the RRCReject message may also be included in the RA report. The waitTime information is used to derive the backoff time for waiting until retrying access.

[0137] Indicator indicating whether SDT failed or succeeded. Specifically, when SDT fails, the reason why SDT is considered to have failed may be included in the RA report. For example, the reason for SDT failure that may be indicated is as follows.

[0138] Receiving an integrity check failure indication from a lower layer while T319a is running,

[0139] Receive an indication from the MCG RLC that the maximum number of retransmissions has been reached while T319a is running,

[0140] Receiving RA problem indication from MCG MAC while T319a is running;

[0141] If T319a expires

[0142] The UE uses the SDT-specific RACH radio resources to perform SDT operations. In this case, the following two methods can be used.

[0143] Method 1: RACH timing is separate for SDT RA and non-SDT RA. The preamble is the same.

[0144] Method 2: RACH timing is the same. In this case, the preamble is different for SDT RA and non-SDT RA.

[0145] Therefore, an indicator indicating which of the two methods is applied may be included in the RA report.

[0146] Scheduled time information (below Figure 1G Description)

[0147] In step 1f-65, UE 1f-05, which has received the RRCRelease message including the suspendConfig IE, switches to the inactive mode.

[0148] In step 1f-70, UE 1f-05 connects to the predetermined gNB 1f-10.

[0149] In step 1f-75, if gNB 1f-10 requests the RA report stored in UE1f-05 through the UEInformationRequest message, in step 1f-80, UE 1f-05 sends a UEInformationResponse message containing the RA report to gNB 1f-10.

[0150] Figure 1G FIG. 1 shows time information related to SDT according to an embodiment.

[0151] The UE may store the time information related to the SDT operation and report it to the base station via the RA report. In this embodiment, the following time information is disclosed.

[0152] Timer A (1g-25): The time between receiving RRCRelease (1g-05) including sdt-Config and SDT completion (1g-20) (or transition to RRC_CONNECTED, 1g-60).

[0153] Timer B (1g-30): The time between receiving RRCRelease (1g-05) including sdt-Config and the start (1g-10) of SDT timer T319a (or the first preamble code is sent).

[0154] Timer C (1g-35): The time between the start of the SDT timer T319a (or the first preamble code is sent) and the completion of the SDT (or the transition to RRC_CONNECTED).

[0155] Timer D (1g-40): The time between the start of the SDT timer T319a (or the first preamble code transmission) and the first SDT data transmission.

[0156] Timer E (1g-45): The time between receiving RRCRelease including sdt-Config and the first SDT data transmission.

[0157] Timer F (1g-50): The time between the start of the SDT timer T319a (or the first preamble code transmission) and the SDT failure.

[0158] Timer G (1g-55): The time between the start of the SDT timer T319a (or the first preamble code transmission) and the arrival of non-SDT data (or non-SDT data indication).

[0159] Timer H (1g-60): The time between the arrival of non-SDT data (or non-SDT data indication) and the entry into RRC_CONNECTED.

[0160] Figure 1H A UE procedure for collecting and reporting SDT-related information according to an embodiment is shown.

[0161] In step 1h-05, the UE sends its capability information to the base station. The capability information includes an indicator (Send UE Capability) indicating that SDT related information can be recorded and reported through RA report.

[0162] In step 1h-10, the UE receives a RRCRelease message including the SDT configuration information and the suspendConfig IE from the base station (receives RRCRelease with suspendConfig IE).

[0163] In steps 1h-15, the UE switches to inactive mode (enters RRC_INACTIVE).

[0164] In step 1h-20, the UE receives system information including configuration information related to SDT from a predetermined base station (receive SIB1).

[0165] In steps 1h-25, the UE compares the received signal strength and data size to be sent with the sdt-RSRP-Threshold field value and the sdt-DataVolumeThreshold field value, and determines to send data through the SDT process (initiate SDT operation). In this case, the UE triggers the RA process by using SDT-specific RACH radio resources.

[0166] In step 1h-30, the UE collects and stores information related to the SDT operation as the content of the RA report (logs the SDT related information as the RA report content).

[0167] In step 1h-35, the UE successfully completes the SDT operation (Complete SDT Operation).

[0168] In step 1h-40, the UE connects to a predetermined base station (enters RRC_CONNECTED).

[0169] In step 1h-45, the UE receives a UEInformationRequest message from the base station requesting a report of the RA report stored therein (receiving retrieval of the RA report).

[0170] In step 1h-50, the UE sends a UEInformationResponse message including a report to the base station (send RA report).

[0171] Fig. 1I A base station process for collecting and reporting SDT related information according to an embodiment is shown.

[0172] In step 1i-05, the gNB receives the capability information of the predetermined UE (receive UE capability). The capability information includes an indicator indicating that the SDT-related information can be recorded and reported through the RA report.

[0173] In step 1i-10, the base station sends an RRCRelease message including the SDT configuration information and the suspendConfig IE to the UE (sending RRCRelease with suspendConfig IE).

[0174] In step 1i-15, the gNB recognizes that the UE has switched to inactive mode (recognizes that the UE enters RRC_INACITVE). In step 1i-20, the gNB broadcasts system information including configuration information related to SDT (broadcast SIB1).

[0175] In step 1i-25, the gNB receives SDT data from the UE through the RA procedure triggered for the purpose of SDT (receiving small data using RA).

[0176] In step 1i-30, the gNB sends a UEInformationRequest message to the UE requesting RA report (requesting retrieval of RA report).

[0177] In step 1i-35, the gNB receives a UEInformationResponse message including a report from the UE (Receive RA Report).

[0178] Figure 1J is a block diagram showing an internal structure of a UE according to an embodiment.

[0179] exist Figure 1J In the embodiment, the UE includes a radio frequency (RF) processor 1j-10, a baseband processor 1j-20, a storage device 1j-30 and a controller 1j-40.

[0180] The RF processor 1j-10 performs functions for sending and receiving signals through a radio channel, such as frequency band conversion and signal amplification. That is, the RF processor 1j-10 converts the baseband signal provided by the baseband processor 1j-20 into an RF band signal, transmits the RF band signal through an antenna, and converts the RF band signal received through the antenna into a baseband signal. For example, the RF processor 1j-10 may include a transmission filter, a reception filter, an amplifier, a mixer, an oscillator, a digital-to-analog converter (DAC), an analog-to-digital converter (ADC), etc. Figure 1J In the figure, only one antenna is shown, but the UE may include multiple antennas. In addition, the RF processor 1j-10 may include multiple RF chains and may perform beamforming. For beamforming, the RF processor 1j-10 may adjust the phase and amplitude of each signal sent and received through multiple antennas or antenna elements. In addition, the RF processor 1j-10 may perform MIMO operations, during which the RF processor 1j-10 may receive multiple layers.

[0181] The baseband processor 1j-20 performs the function of converting between baseband signals and bit streams according to the physical layer standard of the system. For example, when sending data, the baseband processor 1j-20 generates complex symbols by encoding and modulating the transmitted bit stream. In addition, when receiving data, the baseband processor 1j-20 recovers the received bit stream by demodulating and decoding the baseband signal provided from the RF processor 1j-10. For example, in the orthogonal frequency division multiplexing (OFDM) scheme, when sending data, the baseband processor 1j-20 generates complex symbols by encoding and modulating the transmitted bit stream, maps the complex symbols to subcarriers, and then configures OFDM symbols through inverse fast Fourier transform (IFFT) operations and cyclic prefix (CP) insertion. In addition, when receiving data, the baseband processor 1j-20 divides the baseband signal provided by the RF processor 1j-10 into OFDM symbol units, recovers the signal mapped to the subcarrier through a fast Fourier transform (FFT) operation, and then recovers the received bit stream through demodulation and decoding.

[0182] As described above, the baseband processor 1j-20 and the RF processor 1j-10 send and receive signals. Therefore, the baseband processor 1j-20 and the RF processor 1j-10 can be referred to as a transmitter, a receiver, a transceiver, or a communicator. In addition, at least one of the baseband processor 1j-20 and the RF processor 1j-10 may include a plurality of communication modules to support a variety of different radio access technologies. At least one of the baseband processor 1j-20 and the RF processor 1j-10 may include different communication modules to process signals of different frequency bands. For example, different radio access technologies may include a wireless local area network (LAN) (e.g., IEEE802.11), a cellular network (e.g., LTE), and the like. In addition, different frequency bands may include ultra-high frequency (SHF) (e.g., 2.MHz) bands and millimeter wave (e.g., 60GHz) bands.

[0183] The storage device 1j-30 stores data such as basic programs, applications, and configuration information for the operation of the UE. Specifically, the storage device 1j-30 can store information related to a second access node that performs wireless communication by using a second radio access technology. In addition, the storage device 1j-30 provides the stored data according to the request of the controller 1j-40.

[0184] The controller 1j-40 controls the overall operation of the UE. For example, the controller 1j-40 sends and receives signals through the baseband processor 1j-20 and the RF processor 1j-10, writes data into the storage device 1j-30, and reads data. To this end, the controller 1j-40 may include at least one of a communication processor that controls communication and an application processor (AP) that controls an upper layer such as an application.

[0185] Figure 1K is a block diagram showing the structure of an NR base station according to an embodiment.

[0186] As shown in the figure, the base station includes an RF processor 1k-10, a baseband processor 1k-20, a backhaul communicator 1k-30, a storage device 1k-40 and a controller 1k-50.

[0187] The RF processor 1k-10 performs functions for sending and receiving signals through a radio channel, such as frequency band conversion and amplification of signals. That is, the RF processor 1k-10 converts the baseband signal provided by the baseband processor 1k-20 into an RF band signal, sends the RF band signal through the antenna, and converts the RF band signal received by the antenna into a baseband signal. For example, the RF processor 1k-10 may include a transmit filter, a receive filter, an amplifier, a mixer, an oscillator, a DAC, an ADC, etc. Although there is only one antenna, the first access node may include multiple antennas. In addition, the RF processor 1k-10 may include multiple RF chains. In addition, the RF processor 1k-10 can perform beamforming. For beamforming, the RF processor 1k-10 can adjust the phase and amplitude of each signal sent and received through multiple antennas or antenna elements. The RF processor 1k-10 can perform downlink MIMO operations by sending one or more layers.

[0188] The baseband processor 1k-20 performs the function of converting between the baseband signal and the bit stream according to the physical layer standard of the first radio access technology. For example, when sending data, the baseband processor 1k-20 generates complex symbols by encoding and modulating the transmitted bit stream. In addition, when receiving data, the baseband processor 1k-20 recovers the received bit stream by demodulating and decoding the baseband signal provided from the RF processor 1k-10. For example, in the OFDM scheme, when sending data, the baseband processor 1k-20 generates complex symbols by encoding and modulating the transmitted bit stream, maps the complex symbols to subcarriers, and then configures OFDM symbols through IFFT operations and CP insertion. In addition, when receiving data, the baseband processor 1k-20 divides the baseband signal provided by the RF processor 1k-10 into OFDM symbol units, recovers the signal mapped to the subcarrier through FFT operations, and then recovers the received bit stream through demodulation and decoding. As described above, the baseband processor 1k-20 and the RF processor 1k-10 send and receive signals. Therefore, the baseband processor 1k-20 and the RF processor unit 1k-10 can be referred to as a transmitter, a receiver, a transceiver, a communicator, or a wireless communicator.

[0189] The backhaul communicator 1k-30 provides an interface for performing communication with other nodes in the network. That is, the backhaul communicator 1k-30 converts a bit stream sent from the main base station to another node (such as an auxiliary base station or a core network) into a physical signal, and converts a physical signal received from another node into a bit stream.

[0190] The storage device 1k-40 stores data such as basic programs, applications, and configuration information for the operation of the main base station. Specifically, the storage device 1k-40 can store information about the bearer assigned to the accessed UE, the measurement results reported from the accessed UE, etc. In addition, the storage device 1k-40 can store information used as a standard for determining whether to provide or stop multiple connections to the UE. In addition, the storage device 1k-40 provides the stored data according to the request of the controller 1k-50.

[0191] The controller 1k-50 controls the overall operation of the main base station. For example, the controller 1k-50 sends and receives signals through the baseband processor 1k-20 and the RF processor 1k-10 or through the backhaul communicator 1k-30. In addition, the controller 1k-50 writes data into the storage device 1k-40 and reads data. To this end, the controller 1k-50 may include at least one processor.

[0192] FIG. 1A to FIG. 1I The configuration diagrams and views of the control / data signal transmission method and operation process shown in the are not intended to limit the scope of the present disclosure. That is, it should not be interpreted as FIG. 1A to FIG. 1I All constituent units, entities or operational steps shown in the drawings are necessary elements for implementing the present disclosure, and it should be understood that the present disclosure may be implemented by only some of the elements without departing from the basic scope of the present disclosure.

[0193] The above-described operations of the base station or terminal can be implemented by providing a memory device storing corresponding program codes in the base station or terminal device. That is, the controller of the base station or terminal device can perform the above operations by reading and executing the program codes stored in the memory device with the help of a processor or a central processing unit (CPU).

[0194] The various units or modules of the network entity, base station device or terminal device can be operated using hardware circuits such as complementary metal oxide semiconductor based logic circuits, firmware, or hardware circuits such as software and / or a combination of hardware and firmware and / or software embedded in a machine readable medium. For example, various electrical structures and methods can be implemented using transistors, logic gates and circuits such as application specific integrated circuits.

[0195] In this article, it should be understood that each box of the flowchart diagram and the combination of boxes in the flowchart diagram can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device create a means for realizing the functions specified in one or more flowchart boxes. These computer program instructions can also be stored in a computer-available or computer-readable memory, which can instruct the computer or other programmable data processing device to act in a particular way, so that the instructions stored in the computer-available or computer-readable memory produce an article of instruction parts including the functions specified in one or more flowchart boxes. The computer program instructions can also be loaded on a computer or other programmable data processing device so that a series of operating steps are performed on a computer or other programmable device to produce a computer-implemented process so that the instructions executed on the computer or other programmable device provide steps for realizing the functions specified in one or more flowchart boxes.

[0196] In addition, each frame of the flowchart diagram can represent a module, fragment or part of the code, which includes one or more executable instructions for implementing the specified logical function. It should also be noted that in some alternative embodiments, the functions mentioned in the frame may not occur in order. For example, two frames shown in succession can actually be performed substantially simultaneously, or the frames can sometimes be performed in reverse order, depending on the functions involved.

[0197] While the disclosure has been particularly shown and described with reference to certain embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the scope of the subject matter defined by the appended claims and their equivalents.

Claims

1. A method performed by a user equipment (UE) in a wireless communication system, the method comprising: receiving a radio resource control (RRC) release message including first information for a small data transmission (SDT) configuration from a base station; Sending small data to a base station based on the first information; as well as A random access (RA) report including SDT information is sent to the base station.

2. The method according to claim 1, in, The SDT information includes at least one of the following: information corresponding to the first information, an actual reference signal received power (RSRP) value that triggers the SDT, an actual data size that triggers the SDT, an indication of whether the base station supports SDT, an indication of whether the SDT is performed on a normal uplink (NUL) or a supplemental uplink (SUL), an indication of whether the UE has switched to a connected mode after the SDT, an indication of whether the UE has switched to an inactive mode after the SDT, an indication of whether the UE has received an RRC reject message after the SDT, and an indication of whether the SDT has failed.

3. The method according to claim 1, wherein: Sending RA report includes: receiving a UE information request message for RA reporting from a base station in an RRC connected state; and Based on the UE information request message, a UE information response message including the RA report is sent to the base station, Among them, the RA report includes SDT information.

4. The method according to claim 1, further comprising: Sending UE capability information to a base station, the UE capability information including at least one of a first indication of whether the UE supports RA reporting and a second indication of whether the UE supports SDT; receiving, from a base station, system information including second information for SDT configuration; as well as Determining to send small data based on the second information, The second information includes at least one of a first threshold of reference signal received power (RSRP) and a second threshold of data size.

5. A method performed by a base station in a wireless communication system, the method comprising: sending a radio resource control (RRC) release message including first information for small data transmission (SDT) configuration to a user equipment (UE); receiving small data from the UE based on the first information; as well as A random access (RA) report including SDT information is received from the UE.

6. The method according to claim 5, in, The SDT information includes at least one of the following: information corresponding to the first information, an actual reference signal received power (RSRP) value that triggers the SDT, an actual data size that triggers the SDT, an indication of whether the base station supports SDT, an indication of whether the SDT is performed on a normal uplink (NUL) or a supplemental uplink (SUL), an indication of whether the UE has switched to a connected mode after the SDT, an indication of whether the UE has switched to an inactive mode after the SDT, an indication of whether the UE has received an RRC reject message after the SDT, and an indication of whether the SDT has failed.

7. The method according to claim 5, wherein: Receiving RA reports includes: Sending a UE information request message for RA reporting to the UE in the RRC connected state; and receiving, from the UE, a UE information response message including a RA report based on the UE information request message, Among them, the RA report includes SDT information.

8. The method according to claim 5, further comprising: receiving UE capability information from the UE, the UE capability information comprising at least one of a first indication of whether the UE supports RA reporting and a second indication of whether the UE supports SDT; as well as sending system information including second information for SDT configuration to the UE, The second information includes at least one of a first threshold of reference signal received power (RSRP) and a second threshold of data size.

9. A user equipment (UE) in a wireless communication system, the UE comprising: a transceiver configured to transmit or receive signals; and at least one processor, Wherein, the at least one processor is configured to: receiving a radio resource control (RRC) release message including first information for a small data transmission (SDT) configuration from a base station; Sending small data to a base station based on the first information; as well as A random access (RA) report including SDT information is sent to the base station.

10. The UE according to claim 9, in, The SDT information includes at least one of the following: information corresponding to the first information, an actual reference signal received power (RSRP) value that triggers the SDT, an actual data size that triggers the SDT, an indication of whether the base station supports SDT, an indication of whether the SDT is performed on a normal uplink (NUL) or a supplemental uplink (SUL), an indication of whether the UE has switched to a connected mode after the SDT, an indication of whether the UE has switched to an inactive mode after the SDT, an indication of whether the UE has received an RRC reject message after the SDT, and an indication of whether the SDT has failed.

11. The UE according to claim 9, wherein: The at least one processor is further configured to: receiving a UE information request message for RA reporting from a base station in an RRC connected state; and Based on the UE information request message, a UE information response message including the RA report is sent to the base station, Among them, the RA report includes SDT information.

12. The UE according to claim 9, wherein: The at least one processor is further configured to: Sending UE capability information to a base station, the UE capability information including at least one of a first indication of whether the UE supports RA reporting and a second indication of whether the UE supports SDT, receiving system information including second information for SDT configuration from a base station; and Determining to send small data based on the second information, The second information includes at least one of a first threshold of reference signal received power (RSRP) and a second threshold of data size.

13. A base station in a wireless communication system, the base station comprising: a transceiver configured to transmit or receive signals; and at least one processor, Wherein, the at least one processor is configured to: sending a radio resource control (RRC) release message including first information for small data transmission (SDT) configuration to a user equipment (UE); receiving small data from the UE based on the first information; as well as A random access (RA) report including SDT information is received from the UE.

14. The base station according to claim 13, wherein: The at least one processor is further configured to: Sending a UE information request message for RA reporting to the UE in the RRC connected state; Based on the UE Information Request message, receiving a UE Information Response message including the RA report from the UE, and Among them, the RA report includes SDT information, The SDT information includes at least one of the following: information corresponding to the first information, an actual reference signal received power (RSRP) value that triggers the SDT, an actual data size that triggers the SDT, an indication of whether the base station supports SDT, an indication of whether the SDT is performed on a normal uplink (NUL) or a supplemental uplink (SUL), an indication of whether the UE has switched to a connected mode after the SDT, an indication of whether the UE has switched to an inactive mode after the SDT, an indication of whether the UE has received an RRC reject message after the SDT, and an indication of whether the SDT has failed.

15. The base station according to claim 13, wherein: The at least one processor is further configured to: receiving UE capability information from the UE, the UE capability information comprising at least one of a first indication of whether the UE supports RA reporting and a second indication of whether the UE supports SDT, and sending system information including second information for SDT configuration to the UE, The second information includes at least one of a first threshold of reference signal received power (RSRP) and a second threshold of data size.

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