Method and apparatus for supporting user equipment automatic timing advance (TA) update in wireless communication system

Abstract

The present disclosure relates to a 5G or 6G communication system for supporting a higher data transmission rate. According to an embodiment of the present disclosure, a method performed by a user equipment (UE) of a wireless communication system comprises the steps of: receiving, from a base station, a message including configuration information related to sounding reference signal (SRS) transmission during a radio resource control (RRC) inactive state; and instructing a lower layer to update a timing advance (TA) if a cell newly selected through cell reselection includes configuration information in a valid area, wherein the configuration information includes information instructing the UE to autonomously adjust the TA after the cell reselection in the valid area of the configuration information.

Description

Method and device for supporting automatic terminal TA (TIMING ADVANCE) update in a wireless communication system

[0001] The present disclosure relates to the operation of a terminal and a base station in a next-generation mobile communication system. More specifically, the present disclosure relates to a method and device for providing a terminal automatic Timing Advance (TA) update function in a next-generation mobile communication system.

[0002] 5G mobile communication technology defines a wide frequency band to enable fast transmission speeds and new services, and can be implemented not only in the sub-6GHz frequency band such as 3.5 gigahertz (3.5GHz), but also in the ultra-high frequency band called millimeter wave (mmWave) such as 28GHz and 39GHz ('Above 6GHz'). In addition, for 6G mobile communication technology, which is called the system after 5G communication (Beyond 5G), implementation in the terahertz (THz) band (for example, 3 THz band at 95GHz) is being considered to achieve a transmission speed that is 50 times faster than 5G mobile communication technology and an ultra-low latency time that is reduced to one-tenth.

[0003] In the early stages of 5G mobile communication technology, the goal is to support services and satisfy performance requirements for enhanced Mobile Broadband (eMBB), Ultra-Reliable Low-Latency Communications (URLLC), and massive Machine-Type Communications (mMTC). These include beamforming and massive MIMO to mitigate path loss of radio waves in ultra-high frequency bands and increase the transmission distance of radio waves, support for various numerologies (such as operation of multiple subcarrier intervals) and dynamic operation of slot formats for efficient use of ultra-high frequency resources, initial access technology to support multi-beam transmission and wideband, definition and operation of BWP (Bidth Part), new channel coding methods such as LDPC (Low Density Parity Check) codes for large-capacity data transmission and Polar Code for reliable transmission of control information, and L2 pre-processing (L2). Standardization has been made for network slicing, which provides dedicated networks specialized for specific services, and pre-processing.

[0004] Currently, discussions are underway to improve and enhance the initial 5G mobile communication technology in consideration of the services that 5G mobile communication technology was intended to support, and physical layer standardization is in progress for technologies such as V2X (Vehicle-to-Everything) to help autonomous vehicles make driving decisions and increase user convenience based on their own location and status information transmitted by vehicles, NR-U (New Radio Unlicensed) for the purpose of system operation that complies with various regulatory requirements in unlicensed bands, NR terminal low power consumption technology (UE Power Saving), Non-Terrestrial Network (NTN), which is direct terminal-satellite communication to secure coverage in areas where communication with terrestrial networks is impossible, and Positioning.

[0005] In addition, standardization of radio interface architecture / protocols for technologies such as the Industrial Internet of Things (IIoT) to support new services through linkage and convergence with other industries, Integrated Access and Backhaul (IAB) to provide nodes for expanding network service areas by integrating wireless backhaul links and access links, Mobility Enhancement technology including Conditional Handover and Dual Active Protocol Stack (DAPS) handover, and 2-step random access (2-step RACH for NR) to simplify random access procedures is also in progress, and standardization of system architecture / services for 5G baseline architecture (e.g., Service-based Architecture, Service-based Interface) for grafting Network Functions Virtualization (NFV) and Software-Defined Networking (SDN) technologies, and Mobile Edge Computing (MEC) that provides services based on the location of the terminal is also in progress.

[0006] Once these 5G mobile communication systems are commercialized, an explosive increase in connected devices will be connected to the communication network, necessitating enhanced functionality and performance of 5G mobile communication systems and integrated operation of these connected devices. To this end, new research will be conducted on improving 5G performance and reducing complexity, supporting AI services, supporting metaverse services, and drone communications by utilizing eXtended Reality (XR), Artificial Intelligence (AI), and Machine Learning (ML) to efficiently support Augmented Reality (AR), Virtual Reality (VR), and Mixed Reality (MR).

[0007] In addition, the development of these 5G mobile communication systems includes new waveforms to ensure coverage in the terahertz band of 6G mobile communication technology, multi-antenna transmission technologies such as Full Dimensional MIMO (FD-MIMO), Array Antenna, and Large Scale Antenna, metamaterial-based lenses and antennas to improve the coverage of terahertz band signals, high-dimensional spatial multiplexing technology using Orbital Angular Momentum (OAM), Reconfigurable Intelligent Surface (RIS) technology, as well as full duplex technology to improve the frequency efficiency and system network of 6G mobile communication technology, satellite, AI (Artificial Intelligence) from the design stage and AI-based communication technology that realizes system optimization by internalizing end-to-end AI support functions, and ultra-high-performance communication and computing resources to provide services with complexity that exceeds the limits of terminal computing capabilities. It can serve as a basis for the development of next-generation distributed computing technologies that can be realized by utilizing them.

[0008] The present disclosure provides an efficient method for a terminal to update the Timing Advance (TA) value used for uplink transmission. More specifically, the present disclosure proposes a method and device for a terminal to automatically update the TA value used for sounding reference signal transmission of an inactive terminal in a mobile communication system.

[0009] The technical problems to be achieved in the present invention are not limited to the technical problems mentioned above, and other technical problems not mentioned can be clearly understood by a person having ordinary skill in the technical field to which the present invention belongs from the description below.

[0010] Based on the discussion as described above, the present disclosure relates to a method performed by a user equipment (UE) of a wireless communication system, comprising the steps of: receiving, from a base station, a message including configuration information related to sounding reference signal (SRS) transmission during an RRC (radio resource control) inactive state; and, if a cell newly selected through cell reselection is included within a valid area in which the configuration information is valid, instructing a lower layer to update a timing advance (TA).

[0011] The above configuration information is characterized in that it includes information that instructs the terminal to autonomously adjust the TA after cell reselection within an area where the above configuration information is valid.

[0012] In addition, the present invention includes a step of transmitting information indicating whether autonomous TA adjustment of the terminal is supported to the base station, and the information indicating whether autonomous TA adjustment of the terminal is supported is characterized in that it is configured in units of frequency bands.

[0013] In addition, the above setting information is characterized in that it includes information on an area in which the above setting information is valid in relation to the above cell reselection.

[0014] Additionally, if the SRS transmission is ongoing during the RRC inactive state, the method includes a step of instructing the lower layer to update the TA and the stored RSRP (reference signal received power).

[0015] In addition, if the newly selected cell through the cell reselection is included in an area where the configuration information is valid, the method includes a step of instructing the lower layer to update the TA and the stored RSRP (reference signal received power).

[0016] Additionally, if the newly selected cell through the cell reselection is not included in an area where the setting information is valid, a step of transmitting an RRC resume request message to the base station is included.

[0017] In addition, according to one embodiment of the present disclosure, a user equipment (UE) of a wireless communication system includes a transceiver; and a control unit connected to the transceiver, configured to receive, from a base station, a message including configuration information related to sounding reference signal (SRS) transmission during an RRC (radio resource control) inactive state, and instruct a lower layer to update a timing advance (TA) when a cell newly selected through cell reselection is included in a valid area for the configuration information, wherein the configuration information includes information for instructing the UE to autonomously adjust the TA after the cell reselection within the area for which the configuration information is valid.

[0018] In addition, according to one embodiment of the present disclosure, a method performed by a base station of a wireless communication system comprises the steps of: receiving, from a terminal, information indicating whether autonomous TA (timing advance) adjustment of the terminal is supported; transmitting, to the terminal, a message including configuration information related to sounding reference signal (SRS) transmission during an RRC (radio resource control) inactive state; and receiving, from the terminal, an RRC resume request message when a cell newly selected through cell reselection is not included in a valid area for the configuration information.

[0019] When a cell newly selected through the cell reselection is included in an area where the configuration information is valid, a lower layer of the terminal is instructed to update the TA, and the configuration information includes information instructing the terminal to autonomously adjust the TA after the cell reselection within an area where the configuration information is valid and information about an area where the configuration information is valid in relation to the cell reselection.

[0020] In addition, according to one embodiment of the present disclosure, a base station of a wireless communication system comprises a transceiver; and a control unit connected to the transceiver, receiving information from a terminal indicating whether autonomous TA (timing advance) adjustment of the terminal is supported, transmitting a message including configuration information related to sounding reference signal (SRS) transmission during an RRC (radio resource control) inactive state to the terminal, and receiving an RRC resume request message from the terminal when a cell newly selected through cell reselection is not included in a valid area for the configuration information.

[0021] When a cell newly selected through the cell reselection is included in an area where the configuration information is valid, a lower layer of the terminal is instructed to update the TA, and the configuration information includes information instructing the terminal to autonomously adjust the TA after the cell reselection within an area where the configuration information is valid and information about an area where the configuration information is valid in relation to the cell reselection.

[0022] According to one embodiment of the present disclosure, power consumption of a terminal for estimating the location of an inactive terminal can be reduced.

[0023] The effects that can be obtained from the present disclosure are not limited to the effects mentioned above, and other effects that are not mentioned can be clearly understood by a person having ordinary skill in the art to which the present disclosure belongs from the description below.

[0024] The above and other objects, features and advantages of the present disclosure will become more apparent from the following description of embodiments of the present disclosure with reference to the accompanying drawings.

[0025] FIG. 1a is a diagram illustrating the structure of a next-generation mobile communication system according to an embodiment of the present disclosure.

[0026] FIG. 1b is a diagram illustrating a network structure according to one embodiment of the present disclosure.

[0027] FIG. 2 is a diagram illustrating a process for setting up SRS (Sounding Reference Signal) resources of a terminal according to an embodiment of the present disclosure.

[0028] FIG. 3 is a diagram illustrating a process in which a terminal receives SRS transmission configuration information and transmits SRS in an RRC_INACTIVE state according to one embodiment of the present disclosure.

[0029] FIG. 4 is a diagram illustrating a scenario in which a terminal moves in an RRC_INACTIVE state and updates a TA used for SRS transmission by itself while transmitting SRS, according to one embodiment of the present disclosure.

[0030] FIG. 5 is a diagram illustrating a signaling procedure for a terminal to perform an automatic TA update operation in an RRC_INACTIVE state according to one embodiment of the present disclosure.

[0031] FIGS. 6A and 6B are flowcharts illustrating operations when a terminal receives SRS transmission configuration information in an RRC_INACTIVE state according to one embodiment of the present disclosure.

[0032] FIG. 7 is a block diagram illustrating the internal structure of a terminal according to an embodiment of the present disclosure.

[0033] FIG. 8 is a block diagram illustrating the structure of a base station according to an embodiment of the present disclosure.

[0034] The operating principles of the present disclosure will be described in detail below with reference to the attached drawings. In the following description of the present disclosure, detailed descriptions of related known functions or configurations will be omitted if they are deemed to unnecessarily obscure the gist of the present disclosure. Furthermore, the terms described below are defined in consideration of their functions in the present disclosure and may vary depending on the intent or custom of the user or operator. Therefore, their definitions should be based on the contents throughout this specification. Embodiments of the present invention will be described below with reference to the attached drawings.

[0035] For the same reason, some components in the attached drawings are exaggerated, omitted, or schematically depicted. Furthermore, the dimensions of each component do not entirely reflect its actual size. Identical or corresponding components in each drawing are assigned the same reference numbers.

[0036] The advantages and features of the present disclosure, and methods for achieving them, will become clearer with reference to the embodiments described below in detail with the accompanying drawings. However, the present disclosure is not limited to the embodiments disclosed below and may be implemented in various different forms. The embodiments are provided solely to ensure that the present disclosure is complete and to fully inform those skilled in the art of the scope of the disclosure, and the present disclosure is defined solely by the scope of the claims.

[0037] At this time, it will be understood that each block of the processing flowchart drawings and combinations of the flowchart drawings can be performed by computer program instructions. These computer program instructions can be installed in a processor of a general-purpose computer, a special-purpose computer, or other programmable data processing equipment, so that the instructions executed by the processor of the computer or other programmable data processing equipment create a means for performing the functions described in the flowchart block(s). These computer program instructions can also be stored in a computer-available or computer-readable memory that can direct a computer or other programmable data processing equipment to implement the functions in a specific manner, so that the instructions stored in the computer-available or computer-readable memory can also produce a manufactured item that includes an instruction means for performing the functions described in the flowchart block(s). Since the computer program instructions may be installed on a computer or other programmable data processing device, a series of operational steps may be performed on the computer or other programmable data processing device to create a computer-executable process, and the instructions that cause the computer or other programmable data processing device to perform the steps for performing the functions described in the flowchart block(s) may also provide steps for performing the functions described in the flowchart block(s).

[0038] Additionally, each block may represent a module, segment, or portion of code that contains one or more executable instructions for performing a specific logical function(s). It should also be noted that in some alternative implementation examples, the functions described in the blocks may occur out of order. For example, two blocks depicted in succession may actually be executed substantially concurrently, or the blocks may sometimes be executed in reverse order, depending on their respective functions.

[0039] Here, the term '~ unit' used in the present embodiment means software or hardware components such as FPGA (Field Programmable Gate Array) or ASIC (Application Specific Integrated Circuit), and the '~ unit' performs certain roles. However, the '~ unit' is not limited to software or hardware. The '~ unit' may be configured to be on an addressable storage medium and may be configured to play one or more processors. Therefore, as an example, the '~ unit' includes components such as software components, object-oriented software components, class components, and task components, processes, functions, properties, procedures, subroutines, segments of program code, drivers, firmware, microcode, circuits, data, databases, data structures, tables, arrays, and variables. The functions provided within the components and '~ units' may be combined into a smaller number of components and '~ units' or further separated into additional components and '~ units'. Additionally, the components and '~parts' may be implemented to activate one or more CPUs within a device or secure multimedia card. Furthermore, in an embodiment, the '~part' may include one or more processors.

[0040] In the following description of the present disclosure, detailed descriptions of related known functions or configurations will be omitted if they are deemed to unnecessarily obscure the gist of the present disclosure. Hereinafter, embodiments of the present disclosure will be described with reference to the attached drawings.

[0041] The terms used in the following description to identify connection nodes, terms referring to network entities, terms referring to messages, terms referring to interfaces between network entities, and terms referring to various identification information are provided as examples for convenience of explanation. Therefore, the present disclosure is not limited to the terms described below, and other terms referring to objects with equivalent technical meanings may be used.

[0042] For convenience of explanation, this disclosure uses terms and names defined in the 3rd Generation Partnership Project Long Term Evolution (3GPP) LTE standard. However, this disclosure is not limited to the above terms and names and can be equally applied to systems conforming to other standards. In this disclosure, the term "eNB" may be used interchangeably with "gNB" for convenience of explanation. That is, a base station described as an eNB may also represent a gNB.

[0043] Hereinafter, a base station is an entity that performs resource allocation for a terminal, and may be at least one of a gNode B, an eNode B, a Node B, a BS (Base Station), a wireless access unit, a base station controller, or a node on a network. The terminal may include a UE (User Equipment), an MS (Mobile Station), a cellular phone, a smartphone, a computer, or a multimedia system capable of performing a communication function. Of course, the above examples are not limited thereto.

[0044] Furthermore, while the embodiments of the present disclosure are described below using LTE, LTE-A, LTE Pro, or 5G (or NR, next-generation mobile communication) systems as examples, the embodiments of the present disclosure may also be applied to other communication systems with similar technical backgrounds or channel types. Furthermore, the embodiments of the present disclosure may be applied to other communication systems with some modifications, as determined by a person skilled in the art, without significantly departing from the scope of the present disclosure.

[0045] In the following description of the present disclosure, detailed descriptions of related known functions or configurations will be omitted if they are deemed to unnecessarily obscure the gist of the present disclosure. Hereinafter, embodiments of the present disclosure will be described with reference to the attached drawings.

[0046] FIG. 1a is a diagram illustrating the structure of a next-generation mobile communication system according to an embodiment of the present disclosure.

[0047] Referring to FIG. 1a, as illustrated, a radio access network of a next-generation mobile communication system (hereinafter referred to as NR or 2g) may include a next-generation base station (New Radio Node B, hereinafter referred to as NR NB, gNB, NR gNB or NR base station) (1a-10) and an NR CN (1a-05, New Radio Core Network). Of course, the present invention is not limited to the above example, and the radio access network of the next-generation mobile communication system may include more entities. A user terminal (New Radio User Equipment, hereinafter referred to as NR UE or terminal) (1a-15) may access an external network through an NR gNB (1a-10) and an NR CN (1a-05).

[0048] In Fig. 1a, the NR gNB (1a-10) corresponds to the eNB (Evolved Node B) of the existing LTE system. The NR gNB (1a-10) is connected to the NR UE (1a-15) via a wireless channel (1a-20) and can provide a service superior to that of the existing Node B. In the next-generation mobile communication system, since all user traffic is provided through a shared channel, a device that collects status information such as buffer status, available transmission power status, and channel status of UEs and performs scheduling is required, and the NR gNB (1a-10) is responsible for this. One NR gNB (1a-10) can control multiple cells.

[0049] According to one embodiment of the present disclosure, the next-generation mobile communication system may have a bandwidth greater than the existing maximum bandwidth in order to implement ultra-high-speed data transmission compared to the LTE system, and may provide additional beamforming technology using orthogonal frequency division multiplexing (OFDM) as a wireless access technology. In addition, the next-generation mobile communication system may use an adaptive modulation and coding (AMC) method that determines a modulation scheme and a channel coding rate according to the channel condition of the terminal. The NR CN (1a-05) may perform functions such as mobility support, bearer setup, and QoS setup. The NR CN (1a-05) is a device that is responsible for various control functions as well as mobility management functions for the terminal, and may be connected to multiple base stations. In addition, the next-generation mobile communication system may also be interoperable with the existing LTE system, and the NR CN (1a-05) may be connected to an MME (1a-25, mobility management entity) through a network interface. MME can be connected to an existing base station, eNB (1a-30).

[0050] FIG. 1b is a diagram illustrating a network structure according to one embodiment of the present disclosure.

[0051] According to FIG. 1b, a network structure for providing terminal location estimation services in a next-generation mobile communication system according to one embodiment of the present disclosure may be exemplified. The term "terminal location estimation services" may be used interchangeably with the term "LCS" hereinafter.

[0052] Referring to Fig. 1b, a network for providing LCS in a next-generation mobile communication system may be composed of a terminal (1b-01), a base station (NG-RAN Node) (1b-02), an AMF (1b-03, Access and Mobility Function), and an LMF (1b-04, Location Management Function). At this time, the user terminal (1b-01) can communicate with the LMF (1b-04) through the base station (1b-02) and the AMF (1b-03), and exchange information necessary for estimating the terminal's location. The roles of each component for providing LCS are as follows.

[0053] The terminal (UE) (1b-01) can measure a wireless signal required for estimating the location of the terminal and transmit the measurement result to the LMF (1b-04).

[0054] The base station (1b-02) can transmit a downlink wireless signal required for estimating the location of a terminal and measure an uplink wireless signal transmitted by a target terminal.

[0055] After receiving an LCS Request message from an LCS requester, the AMF (1b-03) can request (or instruct) provision of a location provision service for the terminal by transmitting the LCS Request message to the LMF (1b-04). After the LMF (1b-04) processes the LCS (or location estimation) request, it transmits (or responds) a response message regarding the location estimation result of the terminal to the AMF (1b-03), and the AMF (1b-03) that receives the response message (or response) can transmit the location estimation result of the terminal to the LCS requester.

[0056] The LMF (1b-04) may include a device that receives (or receives and processes) an LCS Request from the AMF (1b-03), and may control the overall process required for estimating the position of the terminal. For estimating the position of the terminal, the LMF (1b-04) may provide the terminal (1b-01) with auxiliary information necessary for position estimation and signal measurement, and may obtain (receive) the resulting value. At this time, the LPP (LTE Positioning Protocol) may be used as a protocol for data exchange.

[0057] The above LPP can define the message specifications used between the terminal (1b-01) and the LMF (1b-04) for the position estimation service. In addition, the LMF (1b-04) can exchange the setting information of the downlink reference signal (hereinafter referred to as “Positioning Reference Signal”, PRS) and the measurement results of the uplink reference signal (hereinafter referred to as “Sounding Reference Signal”, SRS) to be used for position estimation with the base station (1b-02). At this time, the NR Positioning Protocol A (NRPPa) can be used as a protocol for data exchange, and the NRPPa can define the message specifications used between the base station (1b-02) and the LMF (1b-04).

[0058] FIG. 2 is a diagram illustrating a process for setting up SRS (Sounding Reference Signal) resources of a terminal according to an embodiment of the present disclosure.

[0059] According to FIG. 2, an example can be provided of a process in which an LMF (2-04) sets up a necessary SRS (Sounding Reference Signal) transmission for a UE (2-01) to perform at least one operation among UL (uplink) or DL+UL (downlink + uplink) positioning methods.

[0060] The above UL positioning method may refer to a method of estimating the location of a terminal based on an uplink signal transmitted by the terminal. For example, it may include a method of estimating the location of the terminal based on SRS measurement information (or measurement result value) acquired by a gNB / TRP (transmission and reception point) that receives (or measures) the SRS signal transmitted by the terminal and transmits an SRS signal via the uplink.

[0061] The above DL+UL positioning method may refer to a method of estimating the position of a terminal based on a downlink signal transmitted by a gNB / TRP and an uplink signal transmitted by a terminal. For example, the gNB / TRP may transmit a PRS (Positioning Reference Signal) via the downlink. A terminal that receives the PRS transmitted by the gNB / TRP may obtain PRS measurement information (or a measured result value). The terminal may transmit an SRS signal via the uplink, and the gNB / TRP that receives (or measures) the SRS signal transmitted by the terminal may obtain SRS measurement information (or a measured result value). Thereafter, the PRS measurement information (or measured result value) measured by the terminal and the SRS measurement information (or measured result value) measured by the gNB / TRP may be used together to estimate the position of the terminal.

[0062] Therefore, in order to estimate the position of a terminal using at least one of the UL positioning method or the UL+DL positioning method, a procedure for configuring the terminal to transmit SRS must be performed. The procedures performed at each step will be described below.

[0063] In step 2-05, LMF (2-04) can exchange NRPPa TRP configuration information with Serving gNB / TRP (2-02) and Neighbor gNB / TRP (2-03). (0. NRPPa TRP Configuration Information Exchange)

[0064] The LMF (2-04) can obtain information necessary for performing the UL positioning method from the Serving gNB / TRP (2-02) and the Neighbor gNB / TRP (2-03). The information necessary for performing the UL positioning method may include at least one of NR cell information, PRS configuration, Spatial Direction information, and location information. In step 2-10, terminal capability information can be exchanged between the LMP (2-04) and the UE (2-01). (1. LPP Capability Transfer)

[0065] LMF (2-04) can request and receive terminal capability information related to location estimation from UE (2-02), and the details can be explained in the following Figure 5.

[0066] In step 2-15, the LMF (2-04) can transmit an NRPPa positioning information request message to the Serving gNB / TRP (2-02). (2. NRPPa POSITIONING INFORMATION REQEST)

[0067] The NRPPa positioning information request message transmitted by the LMF (2-04) may include information for determining the SRS transmission resource configuration of the UE required for UL positioning based on information previously collected by the LMF (e.g., location information of adjacent TRPs, existing location information of the UE, SSB / PRS transmission information of the TRPs, etc.) and requesting the same to the Serving gNB / TRP (2-02). The message may include at least one piece of information from among the number of required SRS resources, periodicity, pathloss reference, and spatial relation.

[0068] In step 2-20, the Serving gNB / TRP (2-02) can finally determine the SRS resources for the UE to transmit SRS. (3. gNB Determines UL SRS Resources)

[0069] After the Serving gNB / TRP (2-02) receives the NRPPa positioning information request message from the LMF (2-04), it can finally determine the SRS resources to be set for the UE based on the received message.

[0070] In step 2-25, the Serving gNB / TRP (2-02) can transmit the SRS resource configuration information (or SRS resource transmission configuration information, UE SRS configuration) determined in step 2-20 to the UE (2-01). (3a. UE SRS configuration)

[0071] The above Serving gNB / TRP (2-02) can transmit the SRS resource configuration information to the UE (2-01) through RRC signaling.

[0072] In step 2-30, the Serving gNB / TRP (2-02) can transmit an NRPPa positioning information response message to the LMF (2-04). (4. NRPPa POSITIONING INFORMATION RESPONSE)

[0073] The NRPPa positioning information response message transmitted by the Serving gNB / TRP (2-02) can be used to transmit the SRS resource configuration information (e.g., time / frequency axis position of the SRS resource, period, spatial relation information, etc.) finally transmitted to the UE (2-01) in step 2-25 to the LMF.

[0074] In step 2-35, the LMF (2-04) may transmit an NRPPa POSITIONING ACTIVATION request message to the Serving gNB / TRP (2-02). (5a. NRPPa POSITIONING ACTIVATION REQUEST)

[0075] The above NRPPa POSITIONING ACTIVATION request message can be used by the LMF (2-04) to request the Serving gNB / TRP (2-02) to activate SRS transmission of the UE (2-01) when the UE (2-01) is configured to transmit semi-persistent or aperiodic SRS.

[0076] In step 2-40, the Serving gNB / TRP (2-02) can be configured to activate SRS transmission to the UE (2-01). (5b. Activate UE SRS transmission)

[0077] This may include a process in which the Serving gNB / TRP (2-02) that has received the above NRPPa POSITIONING ACTIVATION REQUEST message instructs the UE (2-01) to activate SRS through MAC (medium access control) CE (control element) or DCI.

[0078] In step 2-45, the Serving gNB / TRP (2-02) may transmit an NRPPa POSITIONING ACTIVATION RESPONSE message to the UE (2-01). (5c. NRPPA POSITIONING ACTIVATION RESPONSE)

[0079] The above NRPPa POSITIONING ACTIVATION RESPONSE message is a response to the NRPPa POSITIONING ACTIVATION REQUEST message, and can be used by the Serving gNB / TRP (2-02) to transmit information on whether SRS activation is complete (or whether SRS activation is complete) to the LMF (2-04).

[0080] In step 2-55, the LMF (2-04) can transmit an NRPPa MEASUREMENT REQUEST message. (6. NRPPa MEASUREMENT REQUEST)

[0081] The above NRPPa MEASUREMENT REQUEST message may be used by the LMF (2-04) to transmit a request for SRS measurement and result reporting transmitted by the UE to the Serving gNB / TRP (2-02) and the Neighboring gNB / TRP (2-03). At this time, the NRPPa MEASUREMENT REQUEST message may also include SRS resource information set for the UE (2-01).

[0082] In step 2-60, the Serving gNB / TRP (2-02) and the Neighboring gNB / TRP (2-03) can measure the SRS transmitted by the UE (2-01). (7. UE SRS Measurements)

[0083] The Serving gNB / TRP (2-02) and Neighboring gNB / TRP (2-03) that have received a request for SRS measurement from the LMF (2-04) through the NRPPa MEASUREMENT REQUEST message can measure the SRS transmitted by the UE (2-01) based on the SRS configuration information included in the NRPPa MEASUREMENT REQUEST message.

[0084] In step 2-65, the Serving gNB / TRP (2-02) and the Neighboring gNB / TRP (2-03) may transmit an NRPPa MEASUREMENT RESPONSE message to the LMF (2-04). (8. NRPPa MEASUREMENT RESPONSE)

[0085] The above NRPPa MEAUREMENT RESPONSE message can be used by the Serving gNB / TRP (2-02) and Neighboring gNB / TRP (2-03) that received a request for SRS measurement from the LMF (2-04) in step 2-55 described above to transmit the SRS measurement result to the LMF (2-04).

[0086] In step 2-70, the LMF (2-04) may transmit an NRPPa POSITIONING DEACTIVATION message to the Serving gNB / TRP (2-02). (9. NRPPa POSITIONING DEACTIVATION)

[0087] The above NRPPa POSITIONING DEACTIVATION message can be used to transmit to the Serving gNB / TRP (2-02) to deactivate the SRS transmission requested in step 2-35 after the LMF (2-04) completes the position estimation technique operation.

[0088] FIG. 3 is a diagram illustrating a process in which a terminal receives SRS transmission configuration information and transmits SRS in an RRC_INACTIVE state, according to one embodiment of the present disclosure. Furthermore, in this specification, the term "SRS transmission configuration information" may be used interchangeably with the term "SRS configuration information."

[0089] Referring to FIG. 3, the base station (3-05) can transmit an RRCRelease message (3-10) to the terminal (3-10). By transmitting the RRCRelease message to the terminal (3-05), the base station (3-05) can set (or instruct) the terminal (3-01) to transmit SRS in the RRC_INACTIVE state while transitioning the terminal (3-01) to the RRC_INACTIVE state.

[0090] The base station may transmit SRS transmission configuration information (e.g., SRS-PosRRC-Inactive) to be used by the terminal (3-01) in the RRC_INACTIVE state in order to configure (or instruct) the terminal to transmit SRS in the RRC_INACTIVE state for position estimation in the RRCRlease message (3-10). The SRS transmission configuration information may include at least one of SRS transmission resource configuration information (SRS-PosConfig) and BWP (BandWidthPart) configuration information for transmitting the SRS. At this time, the serving base station (3-05) may also configure a valid range (e.g., 'validity area') for the corresponding SRS transmission configuration. For example, the RRCRlease message (3-10) may be transmitted including validity area information. The above validity area can be set in units of srs-PosRRC-InactiveValidityArea, SRS-PosResourceSet, or SRS-POSResource included in the RRCRelease message (3-10). For example, the srs-PosRRC-InactiveValidityArea, SRS-PosResourceSet, or SRS-POSResource configuration information can include a specific validity area or be linked to a specific validity area. The validity area can be set in the form of a list of cells, and each item in the list can include an indicator indicating each cell (for example, a combination of at least one of NR Cell Global ID, PCI, and NR-ARFCN). When the validity area is set in the form of a list of cells as described above, the method in which the terminal interprets the validity area can be one of the following two.

[0091] 1) If the current serving cell is one of the cells included in the cell list representing the validity area, the terminal can be determined to be within the validity area.

[0092] 2) If the terminal can receive downlink reference signals (e.g., SSB, DL-PRS, etc.) from all cells included in the cell list representing the validity area, the terminal can be determined to be within the validity area.

[0093] A terminal that receives an RRCRelease message (3-10) containing SRS transmission configuration information can perform SRS transmission (3-15) even in the RRC_INACTIVE state based on the configured information. In this case, even if the terminal reselects a cell other than the cell to which the RRCRelease message (3-10) containing the SRS transmission configuration information was transmitted due to movement of the terminal (3-02), if the terminal is located within the validity area linked to the SRS configuration information currently being used, the terminal can continue to perform SRS transmission using the corresponding SRS configuration information.

[0094] If the terminal (3-01) is set to transmit SRS in the RRC_INACTIVE state, the terminal (3-01) can only transmit SRS without performing operations that the terminal must perform in the RRC_CONNECTED state.

[0095] When the terminal (3-01) performs SRS transmission in the RRC_INACTIVE state, the terminal can perform only SRS transmission without operations that must be performed in the RRC_CONNECTED state (e.g., PDCCH monitoring, beam management operation, channel estimation operation, etc.), and therefore, the amount of power consumed by the terminal for location estimation of the terminal (3-01) can be reduced.

[0096] The serving base station (3-05) and adjacent base stations (3-06, 3-07) can receive the SRS transmitted by the terminal (3-01) and transmit the SRS measurement results to the LMF. The LMF can estimate the location of the terminal based on the received SRS reception (or measurement) results.

[0097] Meanwhile, if the TA (Timing Advance) value used for SRS transmission is invalid, the terminal may stop SRS transmission. The TA value may refer to information (or value) used to adjust the time at which a signal arrives at the base station when the terminal transmits a signal in the uplink. If multiple terminals at different distances from the base station transmit uplink signals based on their own downlink signal synchronization, the signals transmitted by each terminal may arrive at the base station at different times due to the difference in propagation delay time, which may cause interference between signals. In particular, in OFDM demodulation, interference between OFDM symbols may occur severely if the time synchronization is not correct. Therefore, to prevent the above problem, the base station can estimate the propagation delay time between the base station and the terminal and set an appropriate TA value for each terminal. By setting an appropriate TA value for each terminal, the base station can adjust the uplink signal transmission time of each terminal and prevent interference between uplink signals.

[0098] The TA value used by the above terminal for SRS transmission in the RRC_INACTIVE state may be determined to be invalid if it falls under at least one of the three cases exemplified below.

[0099] 1) When inactivePosSRS-TimeAlignmentTimer (or srs-ValidityAreaTimeAlignmentTimer if a validity area is also set) expires.

[0100] inactivePosSRS-TimeAlignmentTimer or srs-ValidityAreaTimeAlignmentTimer can be started at the time when SRS transmission in RRC_INACTIVE state is established via RRCRelease message (3-10), and can be restarted at the time when the TA value is updated (e.g., when the base station indicates a new TA value via Timing Advance Command MAC CE). Therefore, if the TA value update is not made for a certain period of time (e.g., the inactivePosSRS-TimeAlignmentTimer configuration value), inactivePosSRS-TimeAlignmentTimer or srs-ValidityAreaTimeAlignmentTimer expires and the terminal can determine that the TA value is invalid.

[0101] 2) When the RSRP value of the pathloss reference signal changes by more than the inactivePosSRS-RSRP-ChangeThreshold (or srs-ValidityAreaRSRP-ChangeThreshold if the validity area is also set) value compared to the reference value.

[0102] inactivePosSRS-RSRP-ChangeThreshold or srs-ValidityAreaRSRP-ChangeThreshold can be set together when the terminal is set to transmit SRS in RRC_INACTIVE state via RRCRelease message (3-10). The terminal can store the RSRP (reference signal received power) value of the pathloss reference signal measured at the time when the TA was last updated as a reference value. The pathloss reference signal can be a downlink reference signal transmitted from the serving base station (3-05) or the neighboring base station (3-06, 3-07), and can also be set to the terminal via the RRCRelease message. Thereafter, if the change in the RSRP value of the current pathloss reference signal compared to the stored RSRP reference value becomes larger than the inactivePosSRS-RSRP-ChangeThreshold or srs-ValidityAreaRSRP-ChangeThreshold value, the terminal can determine that the TA value is invalid. That is, if the change in the RSRP value of the pathloss reference signal is greater than a certain level after the TA value update, it means that the change in the distance between the terminal and the base station was large, so the terminal can determine that the TA value is no longer valid.

[0103] The inactivePosSRS-TimeAlignmentTimer (or srs-ValidityAreaTimeAlignmentTimer) and inactivePosSRS-RSRP-ChangeThreshold (or srs-ValidityAreaRSRP-ChangeThreshold) values ​​used for the above TA validation can be included together in the SRS transmission configuration information in the RRC_INACTIVE state and transmitted to the terminal (3-01) through the RRCRelease message (3-10).

[0104] 3) When the terminal reselects another cell.

[0105] When a UE moves in the RRC_INACTIVE state and the conditions for reselection to a different cell are satisfied, the UE can reselect a new cell. If the UE performs cell reselection within the validity area, the UE can maintain the SRS transmission (configuration) it received through the RRCRelease message (3-10). However, if the UE uses the TA value used in the previous serving cell to transmit SRS within the coverage of the newly selected cell, significant interference may occur in the uplink signal reception of the newly selected cell. Therefore, the UE may determine that the TA value used in the previous serving cell is no longer valid.

[0106] If the TA value used by the terminal for SRS transmission in the RRC_INACTIVE state is determined to be invalid due to at least one of the three cases exemplified above, the terminal may stop SRS transmission in the RRC_INACTIVE state. In this case, the base stations (3-05, 3-06, 3-07) that were measuring the SRS transmitted by the terminal for position estimation of the terminal may fail to measure the SRS. Afterwards, the network may attempt to configure SRS transmission again for position estimation of the terminal, and at this time, the terminal must transition to the RRC_CONNECTED state to receive the SRS transmission configuration information again. At this time, the transition of the terminal to the RRC_CONNECTED state may be a major factor that increases the power consumption of the terminal during the position estimation process of the terminal. Therefore, the disclosure of the present invention can propose a method and device for a UE to update a TA value by itself (hereinafter referred to as UE autonomous TA update) when the TA value used for SRS transmission in the RRC_INACTIVE state is invalid or the TA value needs to be updated. The UE autonomous TA update operation can be exemplified in FIG. 4 below.

[0107] FIG. 4 is a diagram illustrating a scenario in which a terminal moves in an RRC_INACTIVE state and updates a TA used for SRS transmission by itself while transmitting SRS, according to one embodiment of the present disclosure.

[0108] Referring to FIG. 4, the terminal (4-01) can be configured to transmit SRS for location estimation in the RRC_INACTIVE state through an RRCRelease message from the previous serving cell (4-05). Thereafter, the terminal can move while maintaining SRS transmission in the RRC_INACTIVE state and perform cell reselection to a new cell (4-07). When performing cell reselection, the terminal can update the TA value by itself according to the time synchronization of the new camping on cell (newly selected cell) (4-07) after cell reselection. A specific operation of the terminal updating the TA value by itself to transmit SRS in the new cell (4-07) after cell reselection can be exemplified as follows.

[0109] When a terminal (4-01) in RRC_INACTIVE state performs SRS transmission within an existing cell (4-05), the terminal can transmit the SRS at a time TA1 (4-25) that is a certain amount of time earlier than the reception timing based on the downlink signal (e.g., SSB1) (4-11) of the cell. This is to match the time at which the SRS transmitted by the terminal arrives at the base station operating the cell (4-05) with the timing (4-10) of the base station. At this time, the TA1 value can be twice the delay time Tp1 (4-22) until the signal actually transmitted from the base station reaches the terminal. The terminal can secure the TA value used for SRS transmission through a random access procedure within the existing cell or reception of a TAC (Timing Advance Command) MAC CE provided by the base station. At this time, the base station can estimate the signal delay time Tp1 (4-22) between the terminal and the base station based on the reception time of the preamble signal transmitted by the terminal during the random access procedure or the reception time of the SRS previously transmitted by the terminal, and calculate the TA1 value based on this.

[0110] When the terminal (4-01) reselects a new cell (4-07), it can update the TA value based on the downlink signal reception timing of the new cell. If the terminal uses the TA value used in the existing serving cell (4-05) to transmit SRS within the coverage of the newly selected cell (4-07), significant interference may occur in the uplink signal reception of the newly selected cell. In this case, if the terminal receives a separate random access procedure and TAC MAC CE to obtain the TA value to be used within the coverage of the new cell (4-07), the terminal may transition from the RRC_INACTIVE state to the RRC_CONNECTED state and consume more energy. In order to prevent additional energy consumption for TA update during such cell reselection, the terminal can update the TA value by itself without the help of the base station. That is, the terminal can perform a UE autonomous TA update operation.

[0111] For the UE autonomous TA update exemplified above, the terminal can calculate the difference value (TP_diff, 4-21) between the downlink signal reception timing of the existing cell (4-05) and the downlink signal reception timing of the new cell (4-07). If the distance between the actual terminal and the new cell (4-07) is different from the distance between the terminal and the existing cell (4-05), a signal delay time difference of Tp_diff (4-21) may occur. The terminal can calculate the TA value (TA2, 4-27) to be used for SRS transmission (4-17) in the new cell using the Tp_diff value and the TA value (TA1, 4-25) used for SRS transmission (4-13) in the existing cell, and can update the TA value used for SRS transmission by itself. For example, if the downlink signal (4-15) of the new cell arrives before the downlink signal (4-11) of the existing cell by Tp_diff(4-21), this means that the transmission delay time (Tp2, 4-20) with the new cell is shorter than the transmission delay time (Tp1, 4-22) with the existing cell by Tp_diff(4-21) because the terminal is closer to the new cell than to the existing cell. Therefore, the terminal can calculate the Tp_2 value as (Tp1 - Tp_diff), and the TA value (TA2, 4-27) to be used in the actual coverage of the new cell can be calculated as 2*Tp2 (=2*Tp1 - 2*Tp_diff = TA1 - 2*Tp_diff).

[0112] The above-described UE autonomous TA update operation can be performed under the assumption that the time synchronization of the existing cell (4-05) and the new cell (4-07) is correct. For example, only under the assumption that the existing cell and the new cell transmit downlink signals (4-11 and 4-15) at the same timing can the UE correctly calculate the Tp_diff (4-21) value and correctly update the new TA values ​​(TA2, 4-27).

[0113] Additionally, although the above embodiment exemplifies the UE autonomous TA update operation only when the terminal performs cell reselection for the sake of ease of explanation, the actual UE autonomous TA update operation may also be performed within the same cell. For example, when the terminal gradually moves away from the base station operating the cell within the same cell coverage, the transmission delay time between the terminal and the base station may increase. In this case, the terminal may detect that the reception timing of the downlink signal of the cell is slightly delayed (pushed back), and the terminal may update the TA value based on the downlink signal reception timing that changes over time even within the same cell. Therefore, in the following FIGS. 5, 6A, and 6B, the related terminal and base station operations may be exemplified under the assumption that the UE autonomous TA update operation may be performed not only in the cell reselection scenario but also in the movement scenario within the same cell.

[0114] FIG. 5 is a diagram illustrating a signaling procedure for a terminal to perform an automatic TA update operation in an RRC_INACTIVE state according to one embodiment of the present disclosure.

[0115] In steps 5-10 and 5-13, the terminal (5-01) can report terminal capability information related to the UE autonomous TA update operation to the serving base station (5-03) and the LMF (5-07).

[0116] In steps 5-15, the LMF may request UE autonomous TA update settings together with requesting the serving base station to set up SRS transmission for the terminal.

[0117] In steps 5-17, the serving base station may provide the terminal with relevant configuration information (e.g., SRS-PosRRC-InactiveValidityArea) via RRCRelease so that the terminal can transmit a location estimation SRS in the RRC_INACTIVE state upon request to the LMF. At this time, configuration information related to UE autonomous TA update may also be provided to the terminal upon request to the LMF.

[0118] In steps 5-20, 5-22, and 5-24, the terminal performs SRS transmission in the RRC_INACTIVE state (5-20), and when the UE autonomous TA update operation is initiated (5-22), the terminal can perform the UE autonomous TA update operation (step 5-24).

[0119] Additionally, in steps 5-26, the terminal can continue SRS transmission after updating the TA value through the Autonomous TA update operation.

[0120] Additionally, in steps 5-28, as needed, the terminal may report to the base station whether UE autonomous TA update has been performed. Specific details of each step may be exemplified as follows, and the names of each message, information, etc. may be replaced with messages or information that perform the same or similar functions or roles, and are not limited to the names exemplified in this disclosure.

[0121] In step 5-10, the terminal (5-01) and the serving base station (5-03) can exchange terminal capability information through an RRC message exchange (e.g., UECapabilityEnquiry or UECapabilityInformation). At this time, the terminal can report terminal capability information related to the UE autonomous TA update operation exemplified in FIG. 4 to the base station. To this end, a new terminal capability information variable indicating whether the UE autonomous TA update operation is supported can be defined in the RRC UECapabilityInformation message. For example, the terminal capability information related to the exemplified UE autonomous TA update operation can indicate whether at least one of the exemplified operations is supported.

[0122] - (positioning SRS) Autonomous TA update

[0123] - (positioning SRS) Autonomous TA adaptation in RRC_INACTIVE

[0124] - (positioning SRS) Autonomous TA adaptation upon cell reselection in RRC_INACTIVE

[0125] - (positioning SRS) Autonomous TA adaptation within current serving(camping on) cell in RRC_INACTIVE

[0126] - Autonomous TA adaptation for positioning SRS Tx in RRC_INACTIVE

[0127] According to one embodiment, the terminal capability information may be reported on a per-terminal basis, a per-frequency band basis, or a per-frequency band combination basis. Additionally, the terminal capability information may be reported separately for each resource operation method of the base station (TDD: Time Division Duplexing or FDD: Frequency Division Duplexing).

[0128] In step 5-13, the terminal (5-01) and the LMF (5-07) can exchange terminal capability information related to the position estimation operation through an LPP message exchange (e.g., RequestCapabilities or ProvideCapabilities). At this time, the terminal can report terminal capability information related to the UE autonomous TA update operation exemplified in FIG. 4 to the LMF. To this end, a new terminal capability information variable indicating whether the UE autonomous TA update operation is supported can be defined in the LPP ProvideCapabilities message. More specifically, the terminal capability information related to the exemplified UE autonomous TA update operation can indicate whether at least one of the following exemplified operations is supported.

[0129] - (positioning SRS) Autonomous TA update

[0130] - (positioning SRS) Autonomous TA adaptation in RRC_INACTIVE

[0131] - (positioning SRS) Autonomous TA adaptation upon cell reselection in RRC_INACTIVE

[0132] - (positioning SRS) Autonomous TA adaptation within current serving(camping on) cell in RRC_INACTIVE

[0133] - Autonomous TA adaptation for positioning SRS Tx in RRC_INACTIVE

[0134] In one embodiment, the terminal capability information may be reported on a per-terminal basis, per-frequency band basis, or per-frequency band combination basis. Furthermore, the terminal capability information may be reported separately for each resource operation method of the base station (Time Division Duplexing (TDD) or Frequency Division Duplexing (FDD).

[0135] In step 5-15, the LMF (5-07) may request the serving base station (5-03) of the position estimation target terminal (5-01) to set up positioning SRS transmission for the terminal through an NRPPa Positioning information request message. At this time, the NRPPa message may include at least one of the information exemplified below.

[0136] Requested SRS Transmission Characteristics: SRS transmission setting information requested by the LMF may be exemplified as shown in [Table 1] below.

[0137] IE / Group NamePresenceRangeIE Type and ReferenceSemantics DescriptionCriticalityAssigned CriticalityNumber Of Periodic TransmissionsC-ifResourceTypePeriodicINTEGER (0..500,...)The number of periodic SRS transmissions requested. The value of '0' represents an infinite number of periodic SRS transmissions.Resource TypeMENUMERATED (periodic, semi-persistent, aperiodic, ...)CHOICEBandwidthM>FR1ENUMERATED (5mHz, 10mHz, 20mHz, 40mHz, 50mHz, 80mHz, 100mHz, ...)>FR2ENUMERATED (50mHz, 100mHz, 200mHz, 400mHz,...)SRS Resource Set List0.. 1>SRS Resource Set Item1.. <maxnosrs-resourcesets>>>Number of SRS Resources Per SetOINTEGER (1..16,...)The number of SRS Resources per resource set for SRS transmission.>>Periodicity List0.. 1>>>Periodicity List Item1.. <maxnosrs-resourceperset>>>>>PeriodicitySRSMENUMERATED (0.125, 0.25, 0.5, 0.625, 1, 1.25, 2, 2.5, 4, 5, 8, 10, 16, 20, 32, 40, 64, 80, 160, 320, 640, 1280, 2560, 5120, 10240, ...)Milli-seconds>>Spatial Relation InformationO9.2.34This IE is ignored if theSpatial Relation Information per SRS ResourceIE is present.>>Pathloss Reference InformationO9.2.53>>Spatial Relation Information per SRS ResourceO9.2.60SSB InformationO9.2.54SRS FrequencyOINTEGER(0..3279165)NR ARFCN The carrier frequency of SRS transmission bandwidth.YESignore

[0138] - Validity area: The LMF may provide the serving base station with information regarding the range within which the requested SRS transmission configuration is valid (e.g., validity area). The validity area information may be defined in the form of a list of cells, and at least one of the NR Cell Global ID, PCI, and NR-ARFCN values ​​of each cell may be included in the list.

[0139] - SRS-autonomousTAupdateReq: The LMF may request the serving base station to configure a UE autonomous TA update operation for the position estimation target terminal. To this end, a UE autonomous TA update operation configuration request indicator (e.g., SRS-autonomousTAupdateReq) may be defined in the NRPPa Positioning information request message. Or, more specifically, the UE autonomous TA update operation configuration request indicator may be defined in the Requested SRS Transmission Characteristics IE.

[0140] - Cell-sync information: As illustrated in FIG. 4, when the UE autonomous TA update operation is performed during the cell reselection process of the terminal, the downlink signal time synchronization of the existing cell and the new cell must be aligned so that the terminal can successfully update the TA value based on the difference in the downlink signal reception timing of the two cells. However, time synchronization between all cells within the validity area of ​​the requested SRS configuration cannot always be guaranteed. In some cases, if the time synchronization of cells located within the validity area is only partially guaranteed, the LMF may additionally provide time synchronization information (e.g., Cell-sync information) between cells within the validity area to the serving base station. More specifically, the Cell-sync information illustrated above may include at least one or more of the following information.

[0141] * One or more lists of time-synchronized cells (or sync area): A list of cells within a validity area for which time synchronization is guaranteed. If there is more than one set of cells for which time synchronization is guaranteed within the validity area, more than one cell list may be included. To represent each cell, at least one of the NR Cell Global ID, PCI, and NR-ARFCN values ​​of each cell may be included in the list. According to an embodiment, cells included in each of the cell lists may mean that they belong to the same sync area. In addition, the sync area may mean a set of cells with downlink signal transmission timing synchronization.

[0142] * Code point or bit string associated with the validity area (list of cells for validity area): In order to indicate cells whose time synchronization is guaranteed among the cells included in the validity area, a Code point or bit string associated with the cell list indicating the validity area may be included. For example, if the cell list indicating the validity area includes three cells (cell 1, cell 2, cell 3), the first three bits of the Code point or bit string may indicate whether the time synchronization of each cell is guaranteed. If the bit string is 110, this may mean that the time synchronization between cell 1 and cell 2 is guaranteed, but the time synchronization between cell 3 and other cells is not guaranteed. This may mean that cells that are indicated to have guaranteed time synchronization with each other through the Code point or bit string belong to the same sync area. In addition, the sync area may mean a set of cells that have the same downlink signal transmission timing synchronization.

[0143] * Sync group ID per each cell belonging to the validity area:

[0144] The sync group ID of each cell included in the validity area may be indicated. For this purpose, a list of Sync group IDs having the same length as the list of cells for validity area indicating the validity area may be included, or each item of the list of cells of validity area may include a Sync group ID along with an identifier for indicating each cell. Time synchronization may be guaranteed between cells having the same Sync group ID. Cells that are indicated to be time synchronized with each other through the Sync group ID may mean that they belong to the same sync area. In addition, the sync area may mean a set of cells that have the same downlink signal transmission timing synchronization.

[0145] * Time offset values ​​for each cell within validity area compared to the last serving cell where the UE receives RRCRelease:

[0146] Even if time synchronization between cells within a validity area is not guaranteed, the UE can perform a UE autonomous TA update operation if time offset information between the downlink signal transmission timings of each cell is provided. For this purpose, time offset information of each cell within the validity area may be included based on the serving cell that received the RRCRelease message immediately before the UE transitioned to the RRC_INACTIVE state. For example, if the time offset information of a specific cell is '0', it may mean that the cell is guaranteed to be time synchronized with the serving cell from which the UE received the RRCRelease message. Conversely, if the time offset information of a specific cell is not '0' but has a value such as xx micro sec / mille sec / frame / slot / symbol, the UE can recognize that the downlink transmission timing of the cell is xx micro sec / mille sec / frame / slot / symbol different from the downlink transmission timing of the serving cell from which the RRCRelease message was received, and can calculate a new TA value by taking this into consideration.

[0147] In step 5-17, the serving base station (5-03) can configure the terminal (5-01) to transmit a position estimation SRS after transitioning to the RRC_INACTIVE state via the RRCRelease message. To this end, SRS transmission configuration information (e.g., SRS-PosRRC-InactiveConfig or SRS-PosRRC-InactiveValidityArea) can be included in the RRCRelease message. At this time, the SRS transmission configuration information can be configured together with the validity area information for which the configuration is valid. The exampled validity area information can refer to the information exampled in step 5-15.

[0148] According to one embodiment, the serving base station may configure the UE to perform a UE autonomous TA update operation while the UE performs a location estimation SRS transmission in the RRC_INACTIVE state according to a request of the LMF in steps 5-15 (e.g., setting the SRS-autonomousTAupdateReq indicator). The configuration information related to the UE autonomous TA update operation (e.g., SRS-AutonomousTAupdate config.) may include at least one of the following exemplified information.

[0149] * DL timing difference threshold (for cell reselection case): When the UE transmits SRS in the RRC_INACTIVE state and performs cell reselection, the base station may be configured to perform the Autonomous TA update procedure only when the difference in downlink signal reception times (DL timing difference) between the existing cell and the new cell (reselected cell) exceeds a specific threshold. To this end, the base station may include information indicating the threshold value of the downlink signal reception time difference in the UE autonomous TA configuration. Signals from two different cells may be transmitted from the same base station, and in this case, even when the UE performs cell reselection from a specific cell to another cell among the two cells, the delay time between the base station and the UE may not change, so there may be no need to perform a TA update. Therefore, unnecessary UE autonomous TA update operations can be avoided (or controlled) through the DL timing difference threshold.

[0150] * Cell Sync information (for cell reselection case): When the UE transmits SRS in RRC_INACTIVE state and then performs cell reselection, the base station may instruct the UE to perform an autonomous TA update operation only when time synchronization between the existing cell and the new cell (reselected cell) is guaranteed (or when downlink transmission timing offset information between the two cells is given even if the time synchronization is different). To this end, the base station may include at least one of the following pieces of information related to time synchronization between cells included in the configured validity area together with SRS transmission configuration information in the RRCRelease message.

[0151] -One or more lists of time-synchronized cells: A list of cells within the validity area for which time synchronization is guaranteed. If there is more than one set of cells within the validity area for which time synchronization is guaranteed, more than one cell list may be included. To represent each cell, at least one of the NR Cell Global ID, PCI, and NR-ARFCN values ​​of each cell may be included in the list.

[0152] - Code point or bit string associated with the validity area (list of cells for validity area): In order to indicate cells within the validity area for which time synchronization is guaranteed, a Code point or bit string associated with the cell list indicating the validity area may be included. For example, if the cell list indicating the validity area includes three cells (cell 1, cell 2, cell 3), the first three bits of the Code point or bit string may indicate whether time synchronization is guaranteed for each cell. If the bit string is 110, this may mean that time synchronization between cell 1 and cell 2 is guaranteed, but time synchronization between cell 3 and other cells is not guaranteed.

[0153] - Sync group ID per each cell belonging to the validity area: The sync group ID of each cell included in the validity area may be indicated. For this purpose, a list of Sync group IDs of the same length as the list of cells for the validity area indicating the validity area may be included, or each item in the list of cells of the validity area may include a Sync group ID along with an identifier for indicating each cell. Time synchronization can be guaranteed between cells having the same Sync group ID.

[0154] - Time offset values ​​for each cell within validity area compared to the last serving cell where the UE receives RRCRelease: Additionally, even if time synchronization between cells within the validity area is not guaranteed, the UE can perform UE autonomous TA update operation if time offset information between downlink signal transmission timings of each cell is provided. For this purpose, time offset information of each cell within the validity area may be included based on the serving cell from which the UE received the RRCRelease message immediately before transitioning to the RRC_INACTIVE state. For example, if the time offset information of a specific cell is '0', it may mean that the cell is guaranteed to be time synchronized with the serving cell from which the UE received the RRCRelease message. Conversely, if the time offset information of a specific cell has a value such as xx micro sec / mille sec / frame / slot / symbol rather than '0', the terminal can recognize that the downlink transmission timing of the cell is different from the downlink transmission timing of the serving cell that received the RRCRelease message by xx micro sec / mille sec / frame / slot / symbol and calculate a new TA value by taking this into consideration.

[0155] In one embodiment, if the base station does not provide any information regarding time synchronization between cells included in the validity area in the UE autonomous TA update configuration information (e.g., SRS-AutonomousTAupdateConfiguration), the terminal may consider that time synchronization between all cells included in the validity area is guaranteed.

[0156] *DL timing difference threshold (for within one cell case): When the UE performs SRS transmission in the RRC_INACTIVE state, the base station may instruct / configure to perform a UE autonomous TA update operation if the reception timing of the downlink signal transmitted by the cell changes by a specific threshold value or more even when cell reselection does not occur and the UE moves only within the coverage of the same cell. To this end, the base station may include information indicating the threshold value of the downlink signal reception timing difference in the UE autonomous TA configuration. According to one embodiment, the base station may set separate DL timing difference thresholds for the cell reselection case and the intra-cell movement case, or may set a common DL timing difference threshold as a UE autonomous TA update operation condition.

[0157] For the related terminal operation according to one embodiment, the downlink signal reception timing of the cell can be calculated / maintained based on the downlink signal reception time measured at the time when the terminal last updated the TA within the specific cell. For example, when the terminal moves within the cell and the distance between the terminal and the base station transmitting the signal of the cell increases, the downlink signal of the base station arrives slightly later than the downlink reception timing calculated / maintained by the terminal as described above, and the terminal can calculate the difference value between the downlink reception timing maintained by the terminal and the downlink reception timing at the current time. For example, when the difference value of the downlink reception timing becomes larger than the DL timing difference threshold value, the UE autonomous TA update operation can be performed even within the same cell.

[0158] * TAT remaining time threshold (for within one cell case): When the UE performs SRS transmission in RRC_INACTIVE state, even if cell reselection does not occur and the UE moves only within the coverage of the same cell, if the remaining time until the TAT timer (e.g., inactivePosSRS-TimeAlignmentTimer or srs-ValidityAreaTimeAlignmentTimer) that the UE is running in relation to SRS transmission expires becomes less than a specific threshold, the base station may instruct / configure to perform a UE autonomous TA update operation. To this end, the base station may include information indicating a threshold value related to the remaining time until the TAT timer exemplified above expires in the UE autonomous TA configuration.

[0159] In step 5-20, the terminal (5-01) can perform location estimation SRS transmission according to the base station (5-03) setting in step 5-17 in the RRC_INACTIVE state.

[0160] In step 5-22, when the terminal (5-01) is performing SRS transmission in the RRC_INACTIVE state, if the UE autonomous TA update operation performance / initiation condition is satisfied according to the base station (5-03) setting in step 5-17, the terminal can trigger the UE autonomous TA update operation for the TA value used for location estimation SRS transmission.

[0161] According to one embodiment, when the terminal performs SRS transmission in the RRC_INACTIVE state and cell reselection is performed, the UE autonomous TA update operation may be triggered in the RRC layer of the terminal. However, the UE autonomous TA update operation may be performed only when the following additional conditions are additionally satisfied according to the UE autonomous TA update configuration (e.g., SRS-AutonomousTAupdate Config.) provided by the base station in steps 5-17.

[0162] - Condition 1-1: First, the terminal can check whether the SRS transmission configuration in step 5-17 is given with a validity area (e.g., whether srs-PosRRC-InactiveValidityAreaIE is set in the RRCRelease message in step 5-17). The terminal can perform the UE autonomous TA update operation during cell reselection only when the SRS transmission configuration is set with a validity area.

[0163] In one embodiment, if the SRS transmission configuration is not set with a validity area, the SRS transmission configuration can be considered valid only within the cell that transmitted the RRCRelease message in steps 5-17, and thus the UE can request a new SRS transmission configuration by transmitting an RRCResumeRequest message without performing a UE autonomous TA update operation upon cell reselection. In this case, the UE can request a new SRS transmission configuration by including a new cause value (e.g., srs-request) in the RRCResumeRequest message.

[0164] - Condition 1-2: Additionally, when performing cell reselection, the terminal can check whether the newly selected cell is included in the validity area associated with the SRS transmission configuration. For example, if the newly selected cell is included in the validity area, the terminal can perform a UE autonomous TA update operation. If the newly selected cell is not included in the validity area, the SRS transmission configuration included in the RRCRelease message in step 5-17 can be considered invalid in the newly selected cell, and therefore, the terminal can request a new SRS transmission configuration by transmitting an RRCResumeRequest message without performing the UE autonomous TA update operation when performing cell reselection. At this time, the terminal can request a new SRS transmission configuration by including a new cause value (e.g., srs-request) in the RRCResumeRequest message.

[0165] - Condition 1-3: Additionally, the terminal can check whether the base station provided UE autonomous TA update configuration (e.g., SRS-AutonomousTAupdate) together with SRS transmission configuration in step 5-17. If the UE autonomous TA update configuration is included in the RRCRelease message in step 5-17, the terminal can perform UE autonomous TA update operation. If the UE autonomous TA update operation is not set, the terminal can maintain the TA value with the base station that received the RRCRelease message in step 5-17 when reselecting a cell or update the TA value through a random access procedure with a newly selected cell.

[0166] - Condition 1-4: In addition, if the UE autonomous TA update setting in the RRCRelease message in step 5-17 includes one or more of the following information as Cell-sync information, the UE may perform the UE autonomous TA update operation only when time synchronization between the existing cell and the newly selected cell is guaranteed when performing cell reselection (for example, when the existing cell and the newly selected cell belong to the same sync area as exemplified in step 5-17). According to an embodiment, the information exemplified below may refer to that exemplified in step 5-17.

[0167] * One or more lists of time-synchronized cells (or sync area)

[0168] * Code point or bit string associated with the validity area (list of cells for validity area)

[0169] * Sync group ID per each cell belonging to the validity area

[0170] Alternatively, if the Cell-sync information includes the 'Time offset values ​​for each cell within validity area compared to the last serving cell where the UE receives RRCRelease' information as exemplified in steps 5-17, the UE may perform a UE autonomous TA update operation even when the synchronization between the existing cell and the newly selected cell is not matched when performing cell reselection. However, in this case, the UE may calculate the TA value by considering the downlink transmission timing difference between the existing cell and the newly selected cell when performing the UE autonomous TA update.

[0171] According to an embodiment, the above conditions 1-1, 1-2, 1-3, or 1-4 may be verified in the RRC layer of the terminal. If the above conditions are satisfied, the RRC layer of the terminal may instruct the MAC layer to update the TA value used for positioning SRS transmission (e.g., perform UE autonomous TA update). Alternatively, if the above conditions are satisfied, the RRC layer of the terminal may only notify the MAC layer of cell reselection, and the UE autonomous TA update operation may be triggered in the MAC layer. The above-mentioned exemplary terminal operation may be exemplified by a specification such as the following [Table 2].

[0172] 1> else if cell reselection occurs when srs-PosRRC-InactiveValidityArea is configured; and1> if the (reselected / current) cell is included in the validity area; and1> if SRS-AutonomousTAupdate is configured by NW; and1> if the (reselected / current / camping on) cell is included in the sync area (or in the same sync area with the last serving cell) if configured: 2> indicates the lower layer (MAC) to adapt the TA value for the positioning SRS Tx (or the TA value associated with PTAG)(or) 2> inform the lower layer (MAC) of cell re-selection event.

[0173] - Condition 1-5: Additionally, the UE can check whether SRS transmission for position estimation was continuously performed at the time of performing cell reselection (for example, whether srs-ValidityAreaTimeAlignmentTimer was continuously running). The UE can perform the UE autonomous TA update operation only if srs-ValidityAreaTimeAlignmentTimer (or inactivePosSRS-TimeAlignmentTimer) is continuously running. - Condition 1-6: Additionally, if the UE autonomous TA update setting in the RRCRelease message in step 5-17 includes a DL timing difference threshold (for cell reselection case) value, the UE can perform the UE autonomous TA update operation only if the downlink signal reception time difference (DL timing difference) between the existing cell and the newly selected cell when performing cell reselection is greater than the DL timing difference threshold value. For example, signals from two different cells may be transmitted from the same base station, and in this case, even if the terminal reselects a specific cell from one of the two cells to another, the delay time between the base station and the terminal may not change, so there may be no need to perform a TA update. Therefore, unnecessary UE autonomous TA update operations can be avoided (or controlled) through the DL timing difference threshold. The above conditions 1-5 and 1-6 can be confirmed at the MAC layer of the terminal.If the above conditions are satisfied, the MAC layer of the terminal may stop the currently running srs-ValidityAreaTimeAlignmentTimer (or, for example, inactivePosSRS-TimeAlignmentTimer) and trigger (or start, perform) a UE autonomous TA update operation for the TA value used for positioning SRS transmission. The above-mentioned exemplary terminal operation may be exemplified in the specification as shown in [Table 3] below.

[0174] The MAC entity shall, if initiated by the upper layers for UE autonomous TA update procedure:1> if srs-ValidityAreaTimeAlignmentTimer is running; and1> if DL timing difference between the last serving(camping) cell and the current serving(camping) cell exceeds the DL-timing-diff threshold (if configured): 2> Stop srs-ValidityAreaTimeAlignmentTimer; and 2> Initiate / trigger / perform UE autonomous TA update procedure with / for the indicated TAG (or PTAG)

[0175] According to one embodiment, when a UE performs cell reselection while transmitting SRS for location estimation in an RRC_INACTIVE state, if at least one combination of conditions 1-1, 1-2, 1-3, 1-4, 1-5, or 1-6 is satisfied, the UE autonomous TA update procedure may be performed. In the embodiment of the present drawing, it is exemplified that condition checking is performed in the RRC layer of the UE for conditions 1-1, 1-2, 1-3, and 1-4, and in the MAC layer of the UE for conditions 1-5 and 1-6. However, the layers in which each condition is actually checked within the UE may be different. Even when the UE performs SRS transmission in an RRC_INACTIVE state without performing cell reselection (for example, when moving only within the coverage range of a specific cell), if one of the conditions exemplified below is satisfied, the UE autonomous TA update operation may be triggered (or started, performed).

[0176] - Condition 2-1: If the UE determines that the existing TA value is invalid due to the expiration of a TA timer (e.g., srs-ValidityAreaTimeAlignmentTimer or inactivePosSRS-TimeAlignmentTimer) or an RSRP change exceeding a specific threshold (e.g., inactivePosSRS-RSRP-ChangeThreshold or inactivePosSRS-ValidityAreaRSRP), and if the UE autonomous TA update setting is received through the RRCRelease message of step 5-17, the UE autonomous TA update procedure can be triggered.

[0177] - Condition 2-2: If the UE autonomous TA update setting in the RRCRelease message of step 5-17 includes 'DL timing difference threshold (for within one cell case)', the UE may trigger the UE autonomous TA update procedure if the difference between the downlink signal reception timing measured at the last TA update time and the downlink signal reception timing measured at the current time exceeds the DL timing difference threshold value. In relation to the operation of the UE according to an embodiment, the downlink signal reception timing of the cell may be calculated / maintained based on the downlink signal reception timing measured at the last TA update time of the UE in a specific cell. For example, if the UE moves within the cell and the distance between the base station transmitting the signal of the cell and the UE increases, the downlink signal of the base station arrives slightly later than the downlink reception timing calculated / maintained by the UE as described above, and the UE may calculate the difference value between the downlink reception timing maintained by the UE and the downlink reception timing at the current time. Additionally, if the difference value of the downlink reception timing becomes greater than the DL timing difference threshold value, UE autonomous TA update operation can be performed even within the same cell.

[0178] - Condition 2-3: If the UE autonomous TA update setting in the RRCRelease message of step 5-17 includes 'TAT remaining time threshold (for within one cell case)', the UE can trigger the UE autonomous TA update procedure when the remaining time until the TA timer (e.g., inactivePosSRS-TimeAlignmentTimer or srs-ValidityAreaTimeAlignmentTimer) that the UE is running in relation to SRS transmission expires becomes less than or equal to the TAT remaining time threshold value.

[0179] The terminal operation exemplified above can be exemplified by the specifications shown in [Table 4] below.

[0180] 1> if UE detects TA invalidation from TAT expiry or RSRP change and SRS-AutonomousTAupdate is configured; or1> if DL timing difference between the last TA update and the current exceeds the DL-timing-diff threshold if configured; or1> if remaining time for TAT expiry reduces under the TA-remaining-time threshold if configured: 2> Stop srs-ValidityAreaTimeAlignmentTimer or inactivePosSRS-TimeAlignmentTimer; and 2> Initiate / trigger / perform UE autonomous TA update procedure with / for the indicated TAG (or PTAG)

[0181] In step 5-24, the terminal (5-01) may calculate a new TA value and perform a UE autonomous TA update procedure to maintain SRS transmission in the RRC_INACTIVE state, as illustrated in FIG. 4. For example, in relation to the UE autonomous TA update procedure, the terminal may perform at least one of the following exemplary operations.

[0182] - TA update: When a new TA value is calculated for the current serving cell (e.g., for the TAG or PTAG to which the current serving cell belongs) for UE autonomous TA update operation, the terminal can update the TA value for the corresponding TAG (or PTAG) to the corresponding value.

[0183] - TAT restart: After the terminal updates the TA value for the TAG or PTAG to which the current serving cell belongs with the newly calculated TA value as in the TA update operation, if there is a position estimation SRS transmission currently in progress, the terminal may restart the TA timer (e.g., inactivePosSRS-TimeAlignmentTimer or srs-ValidityAreaTimeAlignmentTimer) associated with the TAG (or PTAG).

[0184] The above TA update operation and TAT restart operation can be exemplified by the specifications shown in [Table 5] below.

[0185] 1> When a new TA value is calculated for UE autonomous TA update procedure for the current serving / camping on cell (or a TAG / PTAG of the current serving / camping on cell) 2> Apply the new TA value for PTAG (or the indicated TAG) 2> If there is ongoing Positioning SRS Transmission in RRC_INACTIVE as in clause 5.26: 3> Start or Restart srs-ValidityArea-TimerAlignmentTimer / inactivePosSRS-TimeAlignmentTimer associated with PTAG (or the indicated TAG)

[0186] For example, TAG here can mean Timing Advance Group, and different cells can belong to different TAGs. Additionally, PTAG means Primary Timing Advance Group, and the UE's primary cell can refer to the TAG. When a UE transmits a location estimation SRS in the RRC_INACTIVE state, PTAG can refer to the TAG to which the UE is currently camping.

[0187] In addition, even after the UE performs an autonomous TA update for a specific TAG, the terminal may not restart the TA timer (e.g., inactivePosSRS-TimeAlignmentTimer or srs-ValidityAreaTimeAlignmentTimer) connected to the TAG. In this case, while the terminal continues to transmit a location estimation SRS in the RRC_INACTIVE state, the TA timer may eventually expire and the terminal may stop transmitting the SRS. Therefore, the location estimation process for the terminal may eventually fail, and the LMF (5-07) may re-request the serving base station (5-03) of the terminal to configure SRS transmission for the terminal (5-01) as in step 5-15 for new location estimation. In this case, the base station may transition the terminal to the RRC_CONNECTED state for new SRS transmission configuration, which may ultimately result in additional energy consumption of the terminal.

[0188] - Stored RSRP update: After the UE updates the TA value for the TAG or PTAG to which the current serving cell belongs with the newly calculated TA value as in the TA update operation, the UE may update the RSRP value stored for TA validation. For example, after the UE updates the TA value for the TAG or PTAG to which the current serving cell belongs by the UE autonomous TA update procedure, the UE may update the stored RSRP value with the RSRP value of the downlink pathloss reference signal (SSB transmitted by the serving cell or camping on cell) measured at the current point in time. The Stored RSRP update operation may be exemplified by the following specifications in [Table 6].

[0189] 1> else if the UE is configured with SRS transmission in RRC_INACTIVE: 2> if autonomous TA update is finished successfully: 3> Update the stored RSRP of the downlink pathloss reference with the current RSRP value of the downlink pathloss reference.

[0190] In step 5-26, the terminal (5-01) can continue to perform location estimation SRS transmission in the RRC_INACTIVE state using the updated TA value as in step 5-24. In step 5-28, the terminal (5-01) can report to the base station (5-03) whether UE autonomous TA update is performed. If the terminal restarts the TA timer (e.g., inactivePosSRS-TimeAlignmentTimer or srs-ValidityAreaTimeAlignmentTimer) associated with the TAG after performing the UE autonomous TA update for a specific TAG (or PTAG) for location estimation SRS transmission as in step 5-24, the base station may no longer be able to determine whether the TA timer maintained by the terminal has expired. That is, the base station was able to determine whether the TA timer of the terminal has expired because the terminal could generally update the TA value and restart the TA timer only according to the instruction of the base station. And if it is determined that the TA timer (e.g., inactivePosSRS-TimeAlignmentTimer or srs-ValidityAreaTimeAlignmentTimer) related to the operation of performing position estimation SRS transmission by the terminal in the RRC_INACTIVE state has expired, the base station can determine that the SRS transmission resource allocated to the terminal is no longer in use and can allocate the resource to another terminal. However, if the terminal restarts the TA timer on its own after performing the UE autonomous TA update operation as in step 5-24, the base station may not be able to determine whether the terminal is currently continuing to run the TA timer or whether the TA timer has already expired.This means that the synchronization between the base station and the terminal regarding whether the TA timer has expired is not correct, and it may mean that the base station can no longer arbitrarily recover the SRS transmission resources allocated to the terminal based on whether the TA timer has expired. Therefore, in this case, it may be difficult for the base station to efficiently use radio resources. To solve this problem, the terminal may report this to the base station when performing the UE autonomous TA update in steps 5-28 (e.g., when the TA timer is restarted according to the UE autonomous TA update). At this time, a specific reporting method may be exemplified by using Msg1, MAC CE, or RRC message transmission in the random access procedure.

[0191] FIG. 6a and FIG. 6b are flowcharts illustrating operations when a terminal receives SRS transmission configuration information in an RRC_INACTIVE state according to one embodiment of the present disclosure.

[0192] Referring to FIGS. 6a and 6b, the terminal can perform SRS transmission while maintaining the RRC_INACTIVE state based on the configuration information for SRS transmission (e.g., SRS-PosRRC-InactiveConfig or SRS-PosRRC-InactiveValidityArea) included in the RRCRelease in the RRC_INACTIVE state. At this time, if a specific condition is satisfied according to the base station configuration, the terminal can perform a UE autonomous TA update operation to update the TA value used for location estimation SRS transmission. The related specific procedures can be exemplified as follows. FIGS. 6a and 6b can represent one embodiment, and FIG. 6a and FIG. 2gb can be connected and explained through A, B, C, D, and E in the flowchart flow.

[0193] - Receive RRC Release message with SRS-PosRRC-InactiveConfig or SRS-PosRRC-InactiveValidityArea (step 6-01): As in step 5-17 of FIG. 5, the UE may receive an RRC Release message from the serving cell and transition to the RRC_Inactive state. At this time, the RRC Release message may include configuration information (e.g., SRS-PosRRC-InactiveConfig or SRS-PosRRC-InactiveValidityArea) for performing SRS transmission in the RRC_INACTIVE state for position estimation of the UE. In addition, configuration related to UE autonomous TA update operation (e.g., SRS-AutonomousTAupdate IE) may also be included in the RRC Release message.

[0194] - Transmit SRS for positioning in RRC_Inactive state (step 6-02): The terminal can perform SRS transmission for position estimation of the terminal in the RRC_INACTIVE state using the SRS transmission configuration information (e.g., SRS-PosRRC-InactiveConfig or SRS-PosRRC-InactiveValidityArea) received in step 6-01.

[0195] - Cell re-selection? (Step 6-03): If cell re-selection occurs while the terminal is performing location estimation SRS transmission in the RRC_INACTIVE state as in Step 6-02, the terminal can proceed to Step 6-11 below to check whether the newly selected cell belongs to the validity area linked to the SRS transmission settings received in Step 6-01. Conversely, if cell re-selection does not occur, the terminal can check whether the TA value currently used for location estimation SRS transmission is valid as in Step 6-05.

[0196] - TA is valid? (Step 6-05): The UE can check whether the TA value used to perform SRS transmission in the RRC_INACTIVE state is valid. For example, as illustrated in FIG. 3, if the inactivePosSRS-TimeAlignmentTimer (or srs-ValidityAreaTimeAlignmentTimer) expires or the RSRP value of the current pathloss reference signal changes by a value greater than or equal to the inactivePosSRS-RSRP-ChangeThreshold (or inactivePosSRS-RSRP-ChangeThreshold) compared to the RSRP value stored at the last TA update time, the UE can determine that the TA value used for SRS transmission is no longer valid. If the UE determines that the TA value is no longer valid, the UE can proceed to steps 6-10 to check whether the UE autonomous TA update operation is configured (for example, whether the current UE has a valid SRS-autonomousTAupdate IE). Conversely, if the TA value is still valid, you can proceed to step 6-06 to check whether the UE autonomous TA update operation is set.

[0197] - SRS-AutonomousTAupdate is configured? (for within one cell case) (step 6-06): The UE can check whether the UE autonomous TA update operation is configured within the coverage of the same cell. For example, if the UE autonomous TA update operation is not configured within the coverage of the same cell, the UE can return to step 6-02 and continue transmitting the position estimation SRS in the RRC_INACTIVE state. Conversely, if the UE autonomous TA update operation is configured within the coverage of the same cell, the UE can proceed to step 6-07 and check whether the UE autonomous TA update operation condition is satisfied.

[0198] - SRS-AutonomousTAupdate conditions are satisfied? (for within one cell case) (step 6-07): Even if the UE moves only within the coverage range of a specific cell as illustrated in step 5-22 of FIG. 5, if one of the conditions related to the DL timing difference threshold (for within one cell case) or the TAT remaining time threshold (for within one cell case) is satisfied (for example, if conditions 2-2 and 2-3 in step 5-22 of FIG. 5 are satisfied), the UE may proceed to step 6-09 to perform the UE autonomous TA update operation. Conversely, if the above conditions are not satisfied, the UE may return to step 6-02 to continue transmitting the position estimation SRS.

[0199] - Perform autonomous TA update (step 6-09): After performing the autonomous TA update operation as illustrated in step 5-24 of FIG. 5, the terminal returns to step 6-02 and can continue transmitting the location estimation SRS in the RRC_INACTIVE state.

[0200] - SRS-AutonomousTAupdate is configured? (for invalid TA within one cell case) (step 6-10): The UE can check whether the UE autonomous TA update operation is configured within the coverage of the same cell. For example, if the UE autonomous TA update operation is not configured within the coverage of the same cell, the UE can proceed to step 6-20 and stop transmitting the location estimation SRS. Conversely, if the UE autonomous TA update operation is configured within the coverage of the same cell, the UE can proceed to step 6-09 and perform the UE autonomous TA update operation.

[0201] - Within validity area? (Step 6-11): If the terminal reselects a cell while performing SRS transmission in the RRC_INACTIVE state, the terminal can determine whether the SRS transmission configuration in the RRC_INACTIVE state received in Step 6-01 is given together with a validity area (e.g., whether condition 1-1 in Step 5-22 of FIG. 5 is satisfied) and whether the reselected cell is included in the validity area (e.g., whether condition 1-2 in Step 5-22 of FIG. 5 is satisfied). According to an embodiment, if the SRS transmission configuration provided to the terminal in Step 6-01 is not given together with a validity area or the reselected cell is not included in the validity area given together with the SRS transmission configuration in Step 6-01, the terminal can proceed to Step 6-20 to stop SRS transmission and release the SRS transmission configuration in the RRC_INACTIVE state received in Step 6-01. Conversely, if the SRS transmission settings provided to the terminal in step 6-01 are given together with a validity area and the reselected cell is included in the validity area linked to the SRS transmission settings (for example, if both conditions 1-1 and 1-2 in step 5-22 of FIG. 5 are satisfied), the process proceeds to step 6-13 to check whether the UE autonomous TA update operation is set.

[0202] - SRS-AutonomousTAupdate is configured? (for cell re-selection case) (step 6-13): The terminal can check whether the UE autonomous TA update operation is configured (for example, whether conditions 1-3 in step 5-22 of FIG. 5 are satisfied). According to an embodiment, if the UE autonomous TA update operation is not configured during cell re-selection, the terminal can proceed to step 6-20 and stop SRS transmission. Conversely, if the UE autonomous TA update operation is configured during cell re-selection, the terminal can proceed to step 6-15 and check whether the UE autonomous TA update operation condition is satisfied.

[0203] - SRS-AutonomousTAupdate conditions are satisfied? (for cell re-selection case) (step 6-15): When the UE performs cell re-selection as exemplified in step 5-22 of FIG. 5, if specific conditions (conditions 1-4, 1-5, or 1-6 in step 5-17 of FIG. 5) are satisfied according to the UE autonomous TA update configuration (e.g., SRS-AutonomousTAupdateConfiguration) provided by the base station in step 5-17, the UE may proceed to step 6-09 to perform the UE autonomous TA update operation. Conversely, if the conditions are not satisfied, the UE may proceed to step 6-20 and stop SRS transmission.

[0204] - Stop positioning SRS Tx in RRC_INACTIVE state (step 6-20): The terminal may stop positioning SRS transmission in the RRC_INACTIVE state. In addition, the terminal may stop a commonly used TA timer (e.g., SRS-PosRRC-InactiveValidityArea or inactivePosSRS-TimeAlignmentTimer) to manage the validity of the TA value used for the SRS transmission. In addition, the terminal may release the positioning SRS transmission configuration in the RRC_INACTIVE state (e.g., SRS-PosRRC-InactiveConfig or SRS-PosRRC-InactiveValidityArea) provided to the terminal in step 6-01. Additionally, if the UE needs to continue transmitting SRS for position estimation (e.g., if the position estimation SRS transmission is forcibly stopped due to cell reselection or TA invalidation), the UE may request the base station to reset (or activate) the position estimation SRS transmission in the RRC_INACTIVE state via the RRCResumeRequest message. For this purpose, a new resumeCause (e.g., srs-RquestOrActivation) may be defined and included in the RRCResumeReqeust message.

[0205] In the embodiments of FIGS. 3, 4, 5, or 6, the UE autonomous TA update operation and the signaling procedure to support the same may be exemplified with a focus on a scenario in which the UE performs a location estimation SRS transmission in the RRC_INACTIVE state. However, the contents of the present invention are not limited to the scenario in which the UE performs a location estimation SRS transmission in the RRC_INACTIVE state. That is, the UE autonomous TA update operation and the signaling procedure to support the same exemplified through the embodiments of the present invention can be applied to all general UE autonomous TA update operation scenarios in which the UE updates the TA value used for uplink transmission by itself without the assistance of a base station while performing uplink transmission.

[0206] FIG. 7 is a block diagram illustrating the internal structure of a terminal according to an embodiment of the present disclosure.

[0207] Referring to the above drawing, the terminal may include an RF (Radio Frequency) processing unit (7-10), a baseband processing unit (7-20), a storage unit (7-30), and a control unit (7-40).

[0208] The RF processing unit (7-10) above can perform functions for transmitting and receiving signals through a wireless channel, such as signal band conversion and amplification. That is, the RF processing unit (7-10) can up-convert a baseband signal provided from the baseband processing unit (7-20) into an RF band signal and transmit it through an antenna, and down-convert an RF band signal received through the antenna into a baseband signal. For example, the RF processing unit (7-10) can include a transmission filter, a reception filter, an amplifier, a mixer, an oscillator, a digital to analog convertor (DAC), an analog to digital convertor (ADC), etc. In the drawing, only one antenna is shown, but the terminal can be equipped with multiple antennas. In addition, the RF processing unit (7-10) can include multiple RF chains. Furthermore, the RF processing unit (7-10) can perform beamforming. For the above beamforming, the RF processing unit (7-10) can adjust the phase and size of each signal transmitted and received through multiple antennas or antenna elements. In addition, the RF processing unit can perform MIMO (multiple-input and multiple-output) and can receive multiple layers when performing MIMO operation.

[0209] The baseband processing unit (7-20) above can perform a conversion function between a baseband signal and a bit stream according to the physical layer specifications of the system. For example, when transmitting data, the baseband processing unit (7-20) can generate complex symbols by encoding and modulating a transmission bit stream. In addition, when receiving data, the baseband processing unit (7-20) can restore a reception bit stream by demodulating and decoding a baseband signal provided from the RF processing unit (7-10). For example, in the case of following the OFDM (orthogonal frequency division multiplexing) method, when transmitting data, the baseband processing unit (7-20) can generate complex symbols by encoding and modulating a transmission bit stream, map the complex symbols to subcarriers, and then configure OFDM symbols through an inverse fast Fourier transform (IFFT) operation and a cyclic prefix (CP) insertion. In addition, when receiving data, the baseband processing unit (7-20) divides the baseband signal provided from the RF processing unit (7-10) into OFDM symbol units, restores signals mapped to subcarriers through FFT (fast Fourier transform) operation, and then restores the received bit string through demodulation and decoding.

[0210] The baseband processing unit (7-20) and the RF processing unit (7-10) can transmit and receive signals as described above. Accordingly, the baseband processing unit (7-20) and the RF processing unit (7-10) may be referred to as a transmitter, a receiver, a transceiver, or a communication unit. Furthermore, at least one of the baseband processing unit (7-20) and the RF processing unit (7-10) may include a plurality of communication modules to support a plurality of different wireless access technologies. In addition, at least one of the baseband processing unit (7-20) and the RF processing unit (7-10) may include different communication modules to process signals of different frequency bands. For example, the different wireless access technologies may include a wireless LAN (e.g., IEEE 802.11), a cellular network (e.g., LTE), etc. Additionally, the different frequency bands may include a super high frequency (SHF) (e.g., 2.NRHz, NRhz) band and a millimeter wave (mm wave) (e.g., 60GHz) band.

[0211] The storage unit (7-30) can store data such as basic programs, application programs, and setting information for the operation of the terminal. In particular, the storage unit (7-30) can store information related to a second access node that performs wireless communication using a second wireless access technology. In addition, the storage unit (7-30) can provide the stored data at the request of the control unit (7-40).

[0212] The control unit (7-40) can control the overall operations of the terminal. For example, the control unit (7-40) can transmit and receive signals through the baseband processing unit (7-20) and the RF processing unit (7-10). In addition, the control unit (7-40) can record and read data in the storage unit (7-40). For this purpose, the control unit (7-40) can include at least one processor. For example, the control unit (7-40) can include a communication processor (CP) that performs control for communication and an application processor (AP) that controls upper layers such as application programs.

[0213] FIG. 8 is a block diagram illustrating the structure of a base station according to an embodiment of the present disclosure.

[0214] As shown in the above drawing, the base station may be configured to include an RF processing unit (8-10), a baseband processing unit (8-20), a backhaul communication unit (8-30), a storage unit (8-40), and a control unit (8-50).

[0215] The RF processing unit (8-10) may perform functions for transmitting and receiving signals through a wireless channel, such as signal band conversion and amplification. That is, the RF processing unit (8-10) may up-convert a baseband signal provided from the baseband processing unit (8-20) into an RF band signal and transmit the up-converted signal through an antenna, and may down-convert an RF band signal received through the antenna into a baseband signal. For example, the RF processing unit (8-10) may include a transmission filter, a reception filter, an amplifier, a mixer, an oscillator, a DAC, an ADC, etc. In the drawing, only one antenna is shown, but the first access node may have multiple antennas. In addition, the RF processing unit (8-10) may include multiple RF chains. Furthermore, the RF processing unit (8-10) may perform beamforming. For the above beamforming, the RF processing unit (8-10) can adjust the phase and size of each signal transmitted and received through multiple antennas or antenna elements. The RF processing unit can perform a downlink MIMO operation by transmitting one or more layers.

[0216] The baseband processing unit (8-20) above can perform a conversion function between a baseband signal and a bit stream according to the physical layer specifications of the first wireless access technology. For example, when transmitting data, the baseband processing unit (8-20) can generate complex symbols by encoding and modulating a transmission bit stream. In addition, when receiving data, the baseband processing unit (8-20) can restore a reception bit stream by demodulating and decoding a baseband signal provided from the RF processing unit (8-10). For example, in the case of OFDM, when transmitting data, the baseband processing unit (8-20) can generate complex symbols by encoding and modulating a transmission bit stream, map the complex symbols to subcarriers, and then configure OFDM symbols through IFFT operation and CP insertion. In addition, when receiving data, the baseband processing unit (8-20) can divide the baseband signal provided from the RF processing unit (8-10) into OFDM symbol units, restore the signals mapped to subcarriers through FFT operation, and then restore the received bit string through demodulation and decoding. The baseband processing unit (8-20) and the RF processing unit (8-10) can transmit and receive signals as described above. Accordingly, the baseband processing unit (8-20) and the RF processing unit (8-10) can be referred to as a transmitter, a receiver, a transceiver, a communication unit, or a wireless communication unit.

[0217] The above backhaul communication unit (8-30) can provide an interface for performing communication with other nodes within the network. That is, the backhaul communication unit (8-30) can convert a bit string transmitted from the main base station to another node, such as an auxiliary base station or a core network, into a physical signal, and can convert a physical signal received from the other node into a bit string.

[0218] The storage unit (8-40) can store data such as basic programs, application programs, and setting information for the operation of the base station. In particular, the storage unit (8-40) can store information on bearers assigned to connected terminals, measurement results reported from connected terminals, and the like. In addition, the storage unit (8-40) can store information that serves as a judgment criterion for whether to provide or terminate multiple connections to a terminal. In addition, the storage unit (8-40) can provide stored data at the request of the control unit (8-50).

[0219] The control unit (8-50) controls the overall operations of the base station. For example, the control unit (8-50) can transmit and receive signals through the baseband processing unit (8-20) and the RF processing unit (8-10) or through the backhaul communication unit (8-30). In addition, the control unit (8-50) can record and read data in the storage unit (8-40). For this purpose, the control unit (8-50) can include at least one processor.

[0220] Meanwhile, the embodiments of the present invention disclosed in this specification and drawings are merely specific examples presented to easily explain the technical content of the present invention and facilitate understanding of the present invention, and are not intended to limit the scope of the present invention. In other words, it will be apparent to those skilled in the art that other modifications based on the technical concept of the present invention are possible. Furthermore, one or more of the above embodiments may be combined and operated as needed.

[0221] While the detailed description of this disclosure has described specific embodiments, it should be understood that various modifications are possible without departing from the scope of this disclosure. Therefore, the scope of this disclosure should not be limited to the described embodiments, but should be defined not only by the scope of the claims described below, but also by equivalents thereof.

[0222] The operations of the base station or terminal described above can be realized by providing a memory device storing the corresponding program code in any component within the base station or terminal device. That is, the control unit of the base station or terminal device can execute the operations described above by reading and executing the program code stored in the memory device using a processor or CPU (Central Processing Unit).

[0223] The various components and modules of the entity, base station or terminal device described in this specification may be operated using hardware circuits, such as logic circuits based on complementary metal oxide semiconductors, firmware, software and / or hardware and firmware and / or software embedded in a machine-readable medium. For example, various electrical structures and methods may be implemented using electrical circuits such as transistors, logic gates and application-specific semiconductors.

[0224] When implemented in software, a computer-readable storage medium storing one or more programs (software modules) may be provided. The one or more programs stored in the computer-readable storage medium are configured for execution by one or more processors within an electronic device. The one or more programs include instructions that cause the electronic device to execute methods according to the embodiments described in the claims or specification of the present disclosure.

[0225] These programs (software modules, software) may be stored in random access memory, non-volatile memory including flash memory, read only memory (ROM), electrically erasable programmable read only memory (EEPROM), magnetic disc storage device, compact disc ROM (CD-ROM), digital versatile discs (DVDs) or other forms of optical storage device, magnetic cassette. Or, they may be stored in a memory configured as a combination of some or all of these. In addition, each configuration memory may be included in multiple numbers.

[0226] Additionally, the program may be stored in an attachable storage device that is accessible via a communication network such as the Internet, an intranet, a local area network (LAN), a wide local area network (WLAN), a storage area network (SAN), or a combination thereof. Such a storage device may be connected to a device performing an embodiment of the present disclosure via an external port. Additionally, a separate storage device on the communication network may be connected to a device performing an embodiment of the present disclosure.

[0227] In the specific embodiments of the present disclosure described above, components included in the disclosure are expressed in the singular or plural form, depending on the specific embodiment presented. However, the singular or plural expressions are selected to suit the presented situation for convenience of explanation, and the present disclosure is not limited to singular or plural components. Components expressed in the plural form may be composed of singular elements, or components expressed in the singular form may be composed of plural elements.

[0228] While the detailed description of the present disclosure has described specific embodiments, it should be understood that various modifications are possible without departing from the scope of the present disclosure. Therefore, the scope of the present disclosure should not be limited to the described embodiments, but should be determined not only by the scope of the claims described below but also by equivalents of the scope of the claims. In other words, it will be apparent to those skilled in the art to which the present disclosure pertains that other modifications based on the technical idea of ​​the present disclosure are possible. In addition, the above-described embodiments can be combined and operated as needed. For example, parts of the methods proposed in the present disclosure can be combined and operated in a base station and a terminal.

[0229] Additionally, the methods described in each drawing of the present disclosure may include methods for combining at least one drawing according to various implementations. The present disclosure may include methods for combining at least one drawing according to various implementations.

Claims

1. A method performed by a user equipment (UE) of a wireless communication system, A step of receiving a message including configuration information related to SRS (sounding reference signal) transmission during an RRC (radio resource control) inactive state from a base station; and A step of instructing a lower layer to update TA (timing advance) when a newly selected cell through cell reselection is included in a valid area of ​​the above setting information, A method characterized in that the above configuration information includes information instructing the terminal to autonomously adjust the TA after cell reselection within an area where the above configuration information is valid.

2. In paragraph 1, Including a step of transmitting information indicating to the base station whether autonomous TA adjustment of the terminal is supported, A method characterized in that information indicating whether the terminal's own TA adjustment is supported is configured in frequency band units.

3. In paragraph 1, A method characterized in that the above setting information includes information on an area in which the setting information is valid in relation to the cell reselection.

4. In paragraph 1, A method comprising the step of instructing the lower layer to update the TA and stored RSRP (reference signal received power) if the SRS transmission is on-going during the RRC inactive state.

5. In paragraph 1, A method comprising the step of instructing the lower layer to update the TA and stored RSRP (reference signal received power) if the newly selected cell through the cell reselection is included in an area where the configuration information is valid.

6. In paragraph 1, A method comprising the step of transmitting an RRC resume request message to the base station if the newly selected cell through the cell reselection is not included in an area where the configuration information is valid.

7. In the terminal (user equipment, UE) of a wireless communication system, Transmitter and receiver; and Connected to the above transmitter and receiver, A control unit for receiving a message including configuration information related to SRS (sounding reference signal) transmission during an RRC (radio resource control) inactive state from a base station, and instructing a lower layer to update a TA (timing advance) if a newly selected cell through cell reselection is included in a valid area for the configuration information, A terminal characterized in that the above configuration information includes information that instructs the terminal to autonomously adjust the TA after cell reselection within an area where the above configuration information is valid.

8. In paragraph 7, The above control unit transmits information to the base station indicating whether autonomous TA adjustment of the terminal is supported, A terminal characterized in that information indicating whether the terminal's own TA adjustment is supported is configured in frequency band units.

9. In paragraph 7, A terminal characterized in that the above setting information includes information on an area in which the above setting information is valid in relation to the cell reselection.

10. In paragraph 7, The control unit is a terminal that instructs the lower layer to update the TA and the stored RSRP (reference signal received power) when the SRS transmission is on-going during the RRC inactivation state.

11. In paragraph 7, The above control unit is a terminal that instructs the lower layer to update the TA and stored RSRP (reference signal received power) if the newly selected cell through the cell reselection is included in an area where the setting information is valid.

12. In paragraph 7, The above control unit is a terminal that transmits an RRC resume request message to the base station when the newly selected cell through the cell reselection is not included in an area where the setting information is valid.

13. A method performed by a base station of a wireless communication system, A step of receiving information from a terminal indicating whether autonomous TA (timing advance) adjustment of the terminal is supported; A step of transmitting a message including configuration information related to SRS (sounding reference signal) transmission during an RRC (radio resource control) inactive state to the terminal; and A step of receiving an RRC resume request message from the terminal when a newly selected cell through cell reselection is not included in a valid area for the configuration information, If the newly selected cell through the above cell reselection is included in the area where the above setting information is valid, the lower layer of the terminal is instructed to update the TA. A method characterized in that the above configuration information includes information instructing the terminal to autonomously adjust the TA after the cell reselection within an area in which the configuration information is valid and information about an area in which the configuration information is valid in relation to the cell reselection.

14. In a base station of a wireless communication system, Transmitter and receiver; and A control unit connected to the transceiver, receiving information from a terminal indicating whether autonomous TA (timing advance) adjustment of the terminal is supported, transmitting to the terminal a message including configuration information related to SRS (sounding reference signal) transmission during an RRC (radio resource control) inactive state, and receiving an RRC resume request message from the terminal when a newly selected cell through cell reselection is not included in a valid area for the configuration information, If the newly selected cell through the above cell reselection is included in the area where the above setting information is valid, the lower layer of the terminal is instructed to update the TA. A base station characterized in that the above configuration information includes information instructing the terminal to autonomously adjust the TA after the cell reselection within the area where the configuration information is valid and information about the area where the configuration information is valid in relation to the cell reselection.

15. In paragraph 14, Information indicating whether the above terminal's own TA adjustment is supported is organized in frequency band units, A base station, characterized in that when the SRS transmission of the terminal is on-going during the RRC inactivation state, the lower layer of the terminal is instructed to update the TA and the stored RSRP (reference signal received power).

Images