Method and apparatus for performing fast link adaptation based on sounding reference signal in wireless communication system

Abstract

A method of performing fast link adaptation through sounding reference signal (SRS) listening when a handover is required as a user equipment (UE) moves in a wireless communication system. The method comprises: transmitting configuration information of at least one measurement report (MR) to a UE served by a first BS; receiving, from the UE, an MR associated with an event detected by the UE based on the configuration information of the at least one MR; and transmitting, to the at least one second BS, a first message including listening configuration information associated with the SRS transmitted from the UE to the first BS, where the listening configuration information is used to listen for the SRS by the at least one second BS.

Description

Technical Field

[0001] The present disclosure relates to a wireless communication system, and more particularly, to a method and apparatus for performing fast link adaptation using sounding reference signal (SRS) overhearing. Background Art

[0002] Looking back at the development process of successive generations of radio communications, technologies for services (such as voice, multimedia, data, etc.) targeting humans have been developed. It is expected that after the commercialization of the fifth generation (5G) communication system, the connected devices that are in an explosive rise are connected to the communication network. As examples of things connected to the network, there may be cars, robots, drones, household appliances, displays, smart sensors installed in various infrastructures, construction machinery, factory equipment, etc. It is expected that mobile devices will evolve into various form factors, such as augmented reality (AR) glasses, virtual reality (VR) headsets, hologram devices, etc. In order to provide various services by connecting tens of billions of devices and things in the sixth generation (6G) era, efforts are being made to develop better 6G communication systems. For these reasons, 6G communication systems are referred to as super 5G systems.

[0003] In the 6G communication system that is expected to become a reality around 2030, the maximum transmission rate is terabit per second (bps), that is, 1000 gigabits per second, and the maximum wireless delay is 100 microseconds (μsec). In other words, compared with the 5G communication system, in the 6G communication system the transmission rate becomes 50 times faster and the wireless delay is reduced to one tenth (1 / 10).

[0004] In order to obtain these high data transfer rates and ultra-low latency, 6G communication systems are considered to be implemented in the terahertz (THz) band (e.g., ranging from 95 gigahertz (GHz) to 3THz). Due to the more serious path loss and atmospheric absorption phenomena in the THz band compared to the millimeter wave (mmWave) band introduced in the 5G system, it is expected that the importance of the technology for ensuring signal range (i.e., coverage) will grow. As the main technology for ensuring coverage, it is necessary to develop radio frequency (RF) elements, antennas, new waveforms that are superior to orthogonal frequency division multiplexing (OFDM) in terms of coverage, beamforming and massive multiple input multiple output (massive MIMO), full-dimensional MIMO (FFD-MIMO), array antennas, multi-antenna transmission technologies such as massive antennas, etc. In addition, new technologies for increasing THz band signal coverage are being discussed, such as lenses and antennas based on metamaterials, high-dimensional spatial multiplexing technologies using orbital angular momentum (OAM), reconfigurable smart surfaces (RIS), etc.

[0005] In addition, in order to enhance frequency efficiency and system network, full-duplex technology by which both uplink and downlink transmissions are simultaneously transmitted using the same frequency resources, network technology using satellites and high altitude platform stations (HAPS) etc. in combination, network structure innovation technology that supports mobile base stations and allows optimization and automation of network operations, dynamic spectrum sharing technology by conflict avoidance based on spectrum usage prediction, artificial intelligence (AI)-based communication technology (which realizes system optimization by using AI from the design stage and internalizing end-to-end AI support functions), and next-generation distributed computing technology (which realizes services with complexity exceeding the lower limit of terminal computing capabilities by using ultra-high performance communication and computing resources (e.g., mobile edge computing (MEC) cloud)) are being developed in the 6G communication system. In addition, by designing new protocols to be used in the 6G communication system, developing mechanisms for realizing a hardware-based secure environment and secure use of data, and developing technologies for protecting privacy, attempts are being continued to strengthen connectivity between devices, further optimize networks, promote the softening of network entities, and increase the openness of wireless communications.

[0006] With such research and development of 6G communication systems, it is expected that through the hyperconnectivity of the 6G communication system, which includes not only connections between things but also connections between people and things, a new level of the next hyperconnectivity experience becomes possible. Specifically, it is predicted that services such as truly immersive extended reality (truly immersive XR), high-fidelity mobile holograms, digital replicas, etc. can be provided. In addition, services such as remote surgery, industrial automation, and emergency response with enhanced security and reliability can be provided through the 6G communication system to be applied to various fields such as industry, medical care, vehicles, appliances, etc. Summary of the invention

[0007] Embodiments of the present disclosure provide a method and apparatus for performing fast link adaptation through sounding reference signal (SRS) listening when handover is required as a user equipment (UE) moves in a wireless communication system.

[0008] Additional aspects will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the presented embodiments of the disclosure.

[0009] According to an embodiment of the present disclosure, a method for performing communication by a first base station (BS) in a wireless communication system is provided. The method includes: sending configuration information of at least one measurement report (MR) to a user equipment (UE) served by the first BS; receiving an MR associated with an event detected by the UE from the UE based on the configuration information of at least one MR; and sending a first message including listening configuration information associated with a sounding reference signal (SRS) sent from the UE to the first BS to at least one second BS, wherein the listening configuration information is used for the at least one second BS to listen to the SRS.

[0010] According to an embodiment of the present disclosure, a method for performing communication by a second BS in a wireless communication system is provided. The method includes: receiving a first message including listening configuration information associated with an SRS sent from a UE to the first BS from a first BS; sending a response message to the first BS in response to receiving the first message; and receiving the SRS based on the listening configuration information.

[0011] According to an embodiment of the present disclosure, a method for performing communication by a UE in a wireless communication system is provided. The method includes: receiving configuration information of at least one MR from a first BS as a serving BS; and when an event is detected based on the configuration information of the at least one MR, sending an MR associated with the event to the first BS, wherein a first message including the interception configuration information is received by at least one second BS for switching from the first BS based on the received MR, and the at least one second BS receives an SRS sent from the UE to the first BS based on the interception configuration information. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The above and other aspects, features and advantages of certain embodiments of the present disclosure will become more apparent through the following description in conjunction with the accompanying drawings, in which:

[0013] Figure 1 The basic structure of the time-frequency domain as the radio resource domain is shown;

[0014] Figure 2 shows the structure of a UL in which a sounding reference signal (SRS) is transmitted;

[0015] Figure 3 A diagram for describing how to perform fast link adaptation according to an embodiment of the present disclosure is shown;

[0016] Figure 4 A flowchart for describing SRS-based fast link adaptation during handover according to an embodiment of the present disclosure is shown;

[0017] Figure 5A flow chart illustrating application of SRS-based fast link adaptation to random access channel-less (RACH-less) handover according to an embodiment of the present disclosure is shown;

[0018] Figure 6 A flow chart illustrating application of SRS-based fast link adaptation to conditional switching according to an embodiment of the present disclosure is shown;

[0019] Figure 7 A flowchart for describing transmission of an additional message for SRS sensing in SRS-based fast link adaptation according to an embodiment of the present disclosure is shown;

[0020] Figure 8 A flowchart for describing the existence of multiple events in SRS-based fast link adaptation according to an embodiment of the present disclosure is shown;

[0021] Fig. 9 A flowchart for describing additional transmission of an SRS configuration message in SRS-based fast link adaptation according to an embodiment of the present disclosure is shown;

[0022] Fig.10 A diagram showing a plurality of transmission-reception points (TRPs) for describing an embodiment of the present disclosure to which SRS-based sensing is applied is shown;

[0023] Fig.11 A diagram showing application of an SRS-based fast link adaptation method to a base station (BS) configured with multiple TRPs according to an embodiment of the present disclosure;

[0024] Fig. 12A and Fig. 12B A diagram showing a change trend of a transmission rate in a case where an SRS-based fast link adaptation method is performed according to an embodiment of the present disclosure;

[0025] Fig.13 A schematic block diagram showing a configuration of a user equipment (UE) according to an embodiment of the present disclosure is shown; and

[0026] Fig.14 A schematic block diagram showing the configuration of a BS according to an embodiment of the present disclosure. DETAILED DESCRIPTION

[0027] Prior to proceeding with the following description, it may be helpful to set forth definitions of certain words and phrases used throughout this patent document: the terms "include" and "comprising" and their derivatives are meant to include, but are not limited to; the term "or" is inclusive, meaning and / or; the phrases "associated with" and "associated with" and their derivatives may mean include, be included within, interconnected with, contain, be contained within, connect to or be connected with, couple to or be coupled with, communicate with, cooperate with, interleave, juxtapose, be proximate to, be bound to or be bound with, have, have the property of, etc.; and the term "controller" means any device, system, or portion thereof that controls at least one operation, such device may be implemented in hardware, firmware, or software, or some combination of at least two thereof. It should be noted that the functionality associated with any particular controller may be centralized or distributed, whether locally or remotely.

[0028] In addition, the various functions described below can be implemented or supported by one or more computer programs, each of which is formed by a computer-readable program code and embodied in a computer-readable medium. The terms "application" and "program" indicate one or more computer programs, software components, instruction sets, processes, functions, objects, classes, instances, related data or a portion thereof suitable for implementation in a suitable computer-readable program code. The phrase "computer-readable program code" includes any type of computer code, including source code, object code and executable code. The phrase "computer-readable medium" includes any type of medium that can be accessed by a computer, such as a read-only memory (ROM), a random access memory (RAM), a hard drive, a compact disk (CD), a digital video disc (DVD) or any other type of memory. "Non-transitory" computer-readable media excludes wired, wireless, optical or other communication links that transmit temporary electrical signals or other signals. Non-transitory computer-readable media include media that can permanently store data and media that can store data and rewrite it later, such as rewritable optical disks or erasable memory devices.

[0029] Definitions for certain words and phrases are provided throughout this patent document, those of ordinary skill in the art should understand that in many, if not most instances, such definitions apply to prior, as well as future uses of such defined words and phrases.

[0030] Discussed below Figures 1 to 14 The various embodiments used to describe the principles of the present disclosure in this patent document are for illustration only and should not be interpreted in any way as limiting the scope of the present disclosure. Those skilled in the art will appreciate that the principles of the present disclosure can be implemented in any appropriately arranged system or device.

[0031] Embodiments of the present disclosure will now be described in detail with reference to the accompanying drawings.

[0032] Various modifications can be made to the embodiments of the present disclosure, which will be described more fully below with reference to the accompanying drawings. The present disclosure should be understood not to be limited to specific embodiments, but to include all modifications, equivalents, and replacements belonging to the technical scope and concept of the present disclosure.

[0033] Some related well-known technologies that may obscure the present disclosure will not be described. Ordinal numbers (eg, first, second, etc.) as used herein are for distinguishing components from one another.

[0034] Considering the principle of the present disclosure, the terms are selected from the common terms currently widely used, however, the principle of the present disclosure may depend on the intention of ordinary technicians in the field, judicial precedents, the emergence of new technologies, etc. Some of the terms used herein are selected at the discretion of the applicant, in which case the terms will be explained in detail later in conjunction with the embodiments of the present disclosure. Therefore, the terms should be defined based on their meanings and descriptions throughout the disclosure.

[0035] The scope of the present disclosure is defined by the attached claims rather than the detailed description. Various features described in a claim category (e.g., method claims) of the present disclosure may also be claimed in another claim category (e.g., system claims). The embodiments of the present disclosure may include not only a combination of features specified in the attached claims, but also various combinations of individual features in the claims. Those of ordinary skill in the art will understand that various changes in form and detail may be made without departing from the spirit and scope of the present disclosure as defined by the attached claims and their equivalents.

[0036] When the term "connect" or "couple" is used, a component can be directly connected or coupled to another component. However, unless otherwise defined, it should also be understood that a component can be indirectly connected or coupled to another component via another new component. It includes not only the occasion of "direct connection" or "physical connection", but also the occasion of "electrical connection" with another component in the middle. In the present disclosure, the terms "send", "receive" and "communicate" mean both direct and indirect communication.

[0037] The terms "comprising (or including)" or "including (or comprising)" are inclusive or open-ended and do not exclude additional, unrecited elements or method steps.

[0038] Throughout the specification, components expressed as "unit", "module", etc. may be a combination of two or more components, or may be divided into two or more by function. The function may be implemented by hardware, software, or a combination thereof. Each of the components may perform its main function and further perform a part or all of the functions provided by another component. In this way, a part of the main function served by each component may be dedicated and performed by another component.

[0039] As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. All terms used herein, including technical and scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs.

[0040] Throughout the specification, unless specifically mentioned otherwise, the expression "or" is inclusive rather than exclusive. Thus, unless the context clearly indicates otherwise, "A or B" may indicate "A", "B", or both. Throughout this disclosure, the expression "at least one of" or "one or more of" may indicate different combinations of one or more of the listed items, or may indicate occasions when any one of the listed items is required. For example, "at least one of A, B, and C" may include any of the following combinations: A, B, C, A and B, A and C, B and C, or A, B and C.

[0041] Throughout this disclosure, the expression "at least one of a, b, or c" refers to only a, only b, only c, both a and b, both a and c, both b and c, all of a, b, and c, or variations thereof.

[0042] Throughout the specification, a layer may also be referred to as an entity.

[0043] It will be understood that each box and combination of boxes of the flowchart can be performed by computer program instructions. The computer program instructions can be loaded on a processor of a general-purpose computer, a special-purpose computer, or other programmable data processing device, and therefore when executed by the processor of the computer or other programmable data processing device, they generate components for performing the functions described in the box (or multiple) of the flowchart. The computer program instructions can also be stored in a computer-usable or computer-readable memory for a computer or other programmable data processing device, so that a product containing instruction components for performing the functions described in the box (or multiple) of the flowchart can be manufactured. The computer program instructions can also be loaded on a computer or programmable data processing device, so the instructions can generate a process executed by a computer or other programmable data processing device to provide steps for performing the functions described in the box (or multiple) of the flowchart.

[0044] In addition, each block may represent a module, a fragment or a portion of code including one or more executable instructions for performing a specific logical function (or multiple). Note that in some alternative embodiments, the functions described in the blocks may not occur in order. For example, two consecutive blocks may be executed substantially simultaneously or in reverse order.

[0045] Embodiments of the present disclosure will now be described with reference to the accompanying drawings to help those of ordinary skill in the art to easily implement them. However, the embodiments of the present disclosure can be implemented in many different forms and are not limited thereto, as will be discussed herein. In the accompanying drawings, for the sake of clarity, parts not related to the description are omitted, and the same reference numerals represent the same elements throughout the specification.

[0046] Although the following embodiments of the present disclosure will focus on long term evolution (LTE), advanced LTE (LTE-A) or fifth generation (5G) systems as examples, they can be applied to other communication systems with similar technical backgrounds or channel types. For example, other communication systems may include 5G advanced or sixth generation (6G) (super 5G) communication technologies developed after 5G mobile communication technology (NR), and the term 5G may be a concept that includes existing LTE, LTE-A and other similar services. In addition, when judged by a person of ordinary skill in the art, the embodiments of the present disclosure will also be applied to different communication systems with some modifications to the extent that it does not significantly deviate from the scope of the present disclosure.

[0047] Before describing the embodiments of the present disclosure in detail, the terms used herein will be described.

[0048] As will be mentioned later, these terms are defined by taking functions in the present disclosure into consideration, but may vary depending on practices or intentions of users or operators. Therefore, the terms should be defined based on the description throughout this specification.

[0049] A base station (BS) used herein may indicate an entity for performing resource allocation for a user equipment (UE), and may be at least one of a gNode B, an eNode B, a Node B (or an x ​​Node B, where x represents any letter including "g" and "e"), a radio access unit, a BS controller, a satellite, an air vehicle, or a node in a network, but is not limited thereto. In the present disclosure, a BS may indicate a BS itself, a cell, or a radio unit (RU) depending on interpretation, and an entity that exchanges messages with a UE may be a distributed unit (DU) or a central unit (CU) depending on a structure.

[0050] In addition, UE as used herein may include a mobile station (MS), a cellular phone, a smart phone, a computer, a vehicle, a satellite, or a multimedia system capable of performing a communication function.

[0051] In the present disclosure, the term "uplink (UL)" indicates a radio transmission link for a signal transmitted by a UE to a BS.

[0052] In addition, in the present disclosure, a transmit-receive point (TRP) may have the same physical cell identity (PCI) or different PCIs and may indicate an RU or a cell.

[0053] Reference Signal Received Power (RSRP) as used herein indicates the strength of a signal spread over an entire bandwidth and a narrowband.

[0054] The reference signal received quality (RSRQ) in the present disclosure indicates the quality of the number N of resource blocks used for measurement based on the received signal strength indicator (RSSI) and the same bandwidth, which can be obtained by (N*RSRP) / RSSI.

[0055] In the following description, for the convenience of explanation, reference is made to terms related to broadcast information, control information, state changes (e.g., events), network entities, components of messages and devices, terms related to communication coverage, etc. The present disclosure is not limited to the terms to be used in the following description, and different terms having the same meaning in a technical sense may be used.

[0056] In the following description, for ease of explanation, the terms and definitions used in the latest standards among currently existing communication standards (i.e., LTE and NR standards defined in the 3rd Generation Partnership Project (3GPP)) will be used in the present disclosure. However, the present disclosure is not limited to the terms and definitions and can be equally applied to any system conforming to other standards.

[0057] With the development of mobile communication technology, various types of UEs have emerged, and the number of devices owned by each person is increasing. In addition, for 5G technology, beamforming is used to provide wireless communication, which results in an increase in the density of BSs compared to previous technologies due to the limitation of the straightness of the signal. Wireless communication systems that can be provided after 5G have a higher chance of having such features. Highly mobile UEs may include, for example, devices attached to vehicles or mobile objects, wearable devices worn and carried by users, and the like. Wearable devices may include at least one of accessory devices (e.g., watches, rings, wristbands, ankle bands, necklaces, glasses, contact lenses), head-mounted devices (HMDs), clothing or clothing-type devices (e.g., electronic clothing), body-attachable devices (e.g., skin pads), and implantable devices (e.g., implantable circuits), but are not limited thereto.

[0058] As UE mobility and BS density increase, switching may occur frequently. Switching may result in changing the BS to serve the UE and may result in degradation of communication performance during the time it takes to configure information for communication between the changed BS and the UE. For example, significant throughput degradation may occur immediately after switching. The reasons for throughput degradation may include switching interruption time and robust (or conservative) allocation of multiple modulation and coding scheme (MCS) levels and layers, etc. So far, it has been mainly discussed how to solve the throughput degradation caused by switching interruption time. The present disclosure proposes a method for solving the throughput degradation caused by, for example, robust allocation of several MCS levels and layers during switching.

[0059] Figure 1 The basic structure of the time-frequency domain as the radio resource domain is shown.

[0060] refer to Figure 1 , the horizontal axis of the graph represents the time domain, and the vertical axis represents the frequency domain. The minimum transmission unit in the time domain is an orthogonal frequency division multiplexing (OFDM) symbol for downlink (DL) and an OFDM symbol or discrete Fourier transform spread orthogonal frequency division multiplexing (DFT-s-OFDM) symbol for UL.

[0061] When a normal cyclic prefix (NCP) is used in an OFDM symbol or a DFT-s-OFDM symbol, 14 symbols constitute one slot. One subframe is defined as 1 ms. Table 1 shows the number of slots in each of a frame and a subframe depending on a parameter set.

[0062] Table 1. Number of time slots in frames and subframes of OFDM or DFT-S-OFDM according to parameter set

[0063]

[0064] In Table 1, represents the number of symbols included in one slot, which is constantly 14 regardless of the value of μ (parameter set). represents the number of time slots included in one frame depending on the value of μ, and Indicates the number of time slots included in one subframe depending on the value of μ. As the value of μ increases, the number of time slots constituting a frame and a subframe increases. For example, when the value of μ is 1, the number of OFDM symbols per time slot is 14, and one frame has 20 time slots and one subframe has two time slots.

[0065] The smallest transmission unit in the frequency domain is a subcarrier, and the entire system transmission bandwidth consists of a total of subcarriers. refers to the number of resource blocks depending on the value of μ, and is a resource block 120, which may consist of 12 consecutive subcarriers in the frequency domain. The basic resource unit in the time-frequency domain is a resource element (RE) 130, which may be defined by an OFDM / DFT-s-OFDM symbol index and a subcarrier index. Table 2 shows the number of resource blocks corresponding to the maximum or minimum value depending on the value of μ in UL or DL. or The value of .

[0066] Table 2. Number of resource blocks according to parameter set

[0067]

[0068] The wireless communication system adopts a multi-antenna scheme as one of the technologies for UL performance enhancement. Using the single-user (SU) multiple-input multiple-output (MIMO) (SU-MIMO) scheme as a classic example of a multi-antenna scheme, the BS can use up to 4 transmit antennas in the UL to enhance the UL performance. For the SU-MIMO scheme, the BS can estimate the channel state of the entire UL transmission band for the transmit antenna of each UE and determine the precoding matrix to be used by the corresponding UE. The BS can obtain UL channel information for each UE by receiving a sounding reference signal (SRS) sent from the UE. The BS performs determination of the precoding matrix based on the obtained UL channel information for each UE, UL frequency selective scheduling, power control, and MCS level selection.

[0069] Figure 2 The structure of UL in which SRS is transmitted is shown.

[0070] refer to Figure 2 , a time slot 210 may be defined as a basic unit for scheduling signal transmission or reception. Assuming a normal cyclic prefix (CP) length, each time slot has 14 symbols 220, and each symbol may correspond to a UL waveform symbol. For the UL waveform, CP-OFDM or DFT-S-OFDM may be used as examples, and embodiments of the present disclosure may be equally applicable to symbols corresponding to other UL waveforms.

[0071] A resource block (RB) 230 is a resource allocation unit in the frequency domain and has 12 subcarriers.

[0072] The UL structure can be roughly divided into a control region and a data region. In the UL structure, the control region includes time-frequency resources in which a DL channel quality report, an ACK / NACK for DL ​​signal reception, a UL scheduling request, etc. are sent from each UE. The data region of the UL structure includes time-frequency resources in which data such as voice or packet is sent, and corresponds to other resources except the control region among all time-frequency resources.

[0073] In the UL structure, a reference signal (RS) may be transmitted in the data region. The RS transmitted by the UE may include an SRS. The SRS may be used to measure the condition of the UL channel.

[0074] The UE may receive configuration information of the time-frequency resources for sending the SRS from the BS. The configuration information may be received by a higher layer signaling (e.g., a radio resource control (RRC) signaling or a media access control (MAC) control element (CE)). However, this is only an embodiment of the present disclosure, and the time-frequency resources for sending the SRS may be configured by a combination of two or more of an L1 signal and a higher layer signal (e.g., an RRC signal or a MAC CE).

[0075] The segment allowing the transmission of SRS may be limited to a specific symbol area in a time slot. For example, the symbol in which the UE can periodically transmit SRS in a time slot may be in the area 240 of the last 6 symbols. The number N of symbols used for SRS may be set to 1, 2, or 4, and SRS may be transmitted in consecutive symbols. In the frequency domain, resources may be configured in units of multiples of 4 RBs for SRS transmission, and up to 272 RBs may be configured in the frequency domain. However, this is only an example, and SRS may be transmitted in other time resources or frequency resources.

[0076] In addition, the SRS transmission method can be configured by a control signal from the BS. In the present disclosure, the control signal can be a high-level signaling, including RRC signaling or MAC CE signaling, L1 signaling (e.g., DL control indicator (DCI)), or a combination of two or more thereof. In addition, in the present disclosure, information configured by the BS for the UE can be sent in the aforementioned control signal. The SRS can be configured to be transmitted repeatedly. For example, when an SRS antenna port is mapped to one symbol for transmission, up to 4 symbols can be transmitted repeatedly. In contrast, 4 different antenna ports can be mapped to 4 different symbols. This is the case where each antenna port is mapped to one symbol, so repeated transmission of SRS symbols is not allowed.

[0077] The SRS is composed of a constant amplitude zero autocorrelation (CAZAC) sequence. The CAZAC sequences constituting each SRS sent from multiple UEs have different cyclic shift values. Each of the CAZAC sequences generated by cyclic shifting from a CAZAC sequence is characterized as having a zero correlation value with other sequences with different cyclic shift values. By using the above characteristics, the SRSs simultaneously allocated to the same frequency domain can be distinguished by the CAZAC sequence cyclic shift value set for each SRS.

[0078] The SRSs of multiple UEs can be distinguished not only by the cyclic shift value, but also by the frequency position. The frequency position is distinguished by the allocation of SRS subband units or combs. The type of comb can be determined according to the spacing of the subcarriers to which the SRS is allocated in the SRS subband. For example, for Comb2, one SRS is allocated to an even-numbered or odd-numbered subcarrier in the SRS subband, and both the even-numbered subcarriers and the odd-numbered subcarriers constitute one comb.

[0079] The UL channel information estimated based on the SRS can be used for beam management, antenna switching, etc. in the BS. When multiple antennas are used, the UE sends the SRS in a multi-directional beam. Upon receiving the SRS from the UE, the BS can obtain information for the UL channel. For example, using the SRS sent in a multi-directional beam, the channel state in each direction can be found out, and information and a rank value about which beam direction to use can be obtained. Based on the information for the UL channel, the UE performs UL transmission.

[0080] Meanwhile, in an embodiment of the present disclosure, a BS that is not a serving cell may perform fast link adaptation by using an SRS transmitted by a UE. An operation of a BS that is not a serving cell of a UE receiving an SRS of a UE will now be described as overhearing.

[0081] Figure 3 A sequence diagram for describing a method of performing fast link adaptation based on SRS during handover according to an embodiment of the present disclosure is shown.

[0082] refer to Figure 3 , a wireless communication system performing a fast link adaptation method according to an embodiment of the present disclosure may include a first BS 10, at least one second BS 20, and a UE 30. The first BS 10 may be a serving BS of the UE 30.

[0083] The first BS 10 may configure one or more events for a measurement report (MR) for the UE 30 to determine whether to configure interception based on the SRS. When the measurement of a signal sent from the first BS 10 or the second BS 20 to the UE 30 satisfies a preset reference, the UE 30 may recognize that an event has occurred. The reference may be set differently for each event, and the first BS 10 may provide information about the reference for each event to the UE 30 through MR configuration information. When an event occurs, the UE 30 may send an MR to the first BS 10. In an embodiment of the present disclosure, in order to trigger an MR for interception, an event defined for a handover, an event defined for the configuration of multiple transmit-receive points (TRPs), and the like may be used. In an embodiment of the present disclosure, a new event may be defined to trigger an MR for interception.

[0084] When detecting an event regarding the MR configured by the first BS 10, the UE 30 may transmit the MR to the first BS 10. Upon receiving the MR from the UE 30, the first BS 10 may transmit interception configuration information to the second BS 20. The interception configuration information may be transmitted in a handover request message or a message separately defined for interception (e.g., an interception request message).

[0085] The listening configuration information may include SRS configuration information configured by the first BS 10 for the UE 30. The SRS configuration information may include the aforementioned SRS time-frequency resource information and information about the SRS type. The SRS time-frequency resource information may depend on the above combination Figure 1 The parameter set described in the embodiment of the present invention is different, and the SRS time-frequency resource information can be sent together with the information about the parameter set. The SRS type can be set to one of "periodic", "semi-persistent" and "aperiodic". The first BS 10 can provide the SRS configuration information to the UE 30 using a control signal.

[0086] The first BS 10 may activate or deactivate or trigger SRS transmission to the UE through high-layer signaling including RRC signaling or MAC CE signaling or L1 signaling (e.g., DCI). For example, the first BS 10 may activate or deactivate periodic SRS transmission to the UE 30 through high-layer signaling. In addition, the first BS 10 may adjust the length of the SRS period through high-layer signaling.

[0087] The second BS 20 may perform sensing for the SRS transmitted from the UE 30 to the first BS 10 based on the sensing configuration information received from the first BS 10. For example, the second BS 20 may use the SRS configuration information included in the sensing configuration information to identify the time-frequency resource in which the UE 30 transmits the SRS. The second BS 20 may receive a signal in the identified time-frequency resource, and measure a channel state between the UE 30 and the second BS 20 based on the received signal. In the case where the UE 30 performs a handover from the first BS 10 to the second BS 20, the second BS 20 may perform faster link adaptation for communication between the UE 30 and the second BS 20 by measuring the channel state with the UE 30 in advance.

[0088] In the present disclosure, unlike the conventional robust allocation of the MCS level and the number of layers due to the absence of information about the channel between the UE and the BS after the handover, the second BS 20 can allocate the MCS level and the number of layers suitable for the channel state based on the information about the channel state between the second BS 20 and the UE 30 obtained in advance by using SRS listening. The second BS 20 can quickly recover the transmission rate after the handover by allocating the MCS level and the number of layers suitable for the channel state of the UE 30.

[0089] In an embodiment of the present disclosure, UE 30 is a mobile terminal including a cellular phone, a smart phone, a computer, a vehicle, a satellite, or a multimedia system capable of performing a communication function. UE 30 may include a wearable device, which may include at least one of an accessory device (e.g., a watch, a ring, a wristband, an ankle band, a necklace, glasses, contact lenses), a head mounted device (HMD), a clothing or a clothing type device (e.g., an electronic clothing), a body attachable device (e.g., a skin pad), and an implantable device (e.g., an implantable circuit), but is not limited thereto.

[0090] In an embodiment of the present disclosure, the first BS 10 or the second BS 20 may indicate a cell or a radio unit (RU). In addition, depending on a network structure, the first BS 10 or the second BS 20 may indicate a distributed unit (DU) or a central unit (CU).

[0091] although Figure 3 A second BS 20 is shown in FIG. 1 , but it is only an example, and the SRS-based listening according to the present disclosure can also be applied to the occasion when there are multiple second BSs. For example, in the case of conditional handover, multiple second BSs can be set as candidates for the target BS, in which case each of the multiple second BSs can be configured to perform SRS-based listening.

[0092] In addition, the SRS-based listening according to the present disclosure can also be applied to traditional handover, handover without radio access channel (RACH), conditional handover, dual-active protocol handover, etc., but is not limited thereto. Figures 4 to 6 An embodiment of a specific switching operation is described in detail.

[0093] Figure 4 A flowchart for describing a method for performing fast link adaptation based on SRS during handover according to an embodiment of the present disclosure is shown.

[0094] In operation S410, the first BS 10 may transmit information about configuration of at least one MR to the UE 30. For convenience of explanation, the information about configuration of at least one MR will now be referred to as MR configuration information.

[0095] When the measurement of the signal transmitted from the first BS 10 or the second BS 20 satisfies the preset condition, the MR may be transmitted from the UE 30 to the first BS 10. The preset condition may be different for each event defined by the first BS 10, and information on the MR transmission condition for each event may be included in the MR configuration information. In the disclosure, when the preset condition for each event is met, it is described as an event that triggers the MR to be detected.

[0096] The UE 30 may compare the measurement of the signal received from the first BS 10 or the second BS 20 with the offset or threshold set for the Ax event, and perform MR transmission based on the result of the comparison. X is an index for distinguishing events and may be set differently for each event. For example, when the measurement of the signal received by the UE 30 from the neighboring BS is greater than the measurement of the signal received from the PCell or PSCell by a set offset, an A3 event may occur.

[0097] MR configuration information of the A3 event may be provided as in the following Table 3. The MR configuration information of the A3 event may include a3-Offset representing an offset value, a hysteresis parameter of the A3 event, a trigger time, and measurements of the first BS 10 and the second BS 20 .

[0098] Table 3. MR configuration information about event A3

[0099]

[0100] In the present disclosure, an event for SRS listening can be configured, and the event for SRS listening can be described as an Ax event. The event that triggers the MR for SRS listening may include an event that triggers a traditionally defined MR for switching, an event that triggers an MR for multi-TRP configuration, etc., which will be described in detail later.

[0101] Table 4. mr configuration information for two or more events

[0102]

[0103] In an embodiment of the present disclosure, MR configuration information may be provided for two or more events. For example, when the BS configures two or more events for the UE 30, it may configure different offsets in a method of allocating different reportConfigIds including a value for triggering the MR for each measObjectId, where the measObjectId is information indicating a measurement target in the MR configuration information. For example, reportconfigID1 is configured for an Ax event to trigger an MR for switching, and reportconfigID2 is configured for an Ax event to trigger an MR for SRS listening, thereby making a difference in the offset value. The MR configuration information may include events related to switching and events related to SRS listening. The offset of an event related to switching may be set to a value greater than the offset of an event related to SRS listening. In operation S420, the UE 30 may detect an event corresponding to the MR configuration information. When the measurement of a signal received from the first BS 10 satisfies a condition of an event configured based on the MR configuration information, the UE 30 may detect an event. For example, the UE 30 may detect at least one of an event related to switching, an event related to SRS listening, or an event related to a multi-TRP configuration. In operation S430 , the UE 30 may transmit an MR corresponding to the event to the first BS 10 .

[0104] In an embodiment of the present disclosure, the MR corresponding to the event may include information about the signal strength and quality of the first BS 10 and the second BS 20. For example, the information about the signal strength and quality may include reference signal received power (RSRP), reference signal received quality (RSRQ), and signal to interference and noise ratio (SINR). The MR may also include information about a physical cell identity (PCI) corresponding to the signal strength and quality.

[0105] In an embodiment of the present disclosure, when one or more cells exist in the PCI transmitted in the MR information, the first BS 10 may request a cell ID for handover from the UE 30. The UE 30 may determine a cell ID corresponding to the request of the first BS 10 and transmit information about the cell ID to the first BS 10. For example, when the cell ID received in response to the request of the first BS 10 is the cell ID of the second BS 20, the first BS 10 may transmit a handover request to the second BS 20 based on the received cell ID.

[0106] In operation S440, the first BS 10 may transmit a handover request to the second BS 20. Upon receiving the MR corresponding to the detected event, the first BS 10 may transmit a handover request to a target for handover, which is the second BS 20.

[0107] In an embodiment of the present disclosure, the handover request may include a transparent RRC container, which includes the handover preparation information RRC message and the ID of the second BS 20 and other information.

[0108] In an embodiment of the present disclosure, the handover request may include resource information for handover. The resource information for handover may include other information depending on the handover type. Figure 5 and Figure 6 Embodiments of RACH-free handover and conditional handover are described in detail.

[0109] In an embodiment of the present disclosure, the handover request may include a request for SRS listening. The request for SRS listening may include information indicating activation of SRS listening and information for configuring SRS listening. In an embodiment of the present disclosure, the listening request may be included in a transparent RRC container accompanying the handover request, or delivered by a vendor-specific method. For example, the request for SRS listening may be configured via an "RRC: srs-Config setup" information element (IE) in an RRC message. However, this is merely an example and will be described later in conjunction with Figure 5 A specific embodiment of the SRS listening request is described below.

[0110] In operation S450, the second BS 20 may transmit a response to the handover request to the first BS 10. The second BS 20 may receive the handover request and transmit ACK or NACK for the handover request.

[0111] In an embodiment of the present disclosure, the response to the handover request may include a response to the SRS listening request. When the SRS resource information for listening and the resource information scheduled for the UE served by the second BS 20 conflict with each other or when the second BS 20 has no space for PHY processing capacity, the second BS 20 may send a NACK for the SRS listening request.

[0112] The second BS 20 may send a response to the listening request for each SRS resource ID. In an embodiment of the present disclosure, the response to the listening request may be represented by using a bitmap corresponding to the SRS resource ID. The second BS 20 may not respond to resources for which the SRS listening request has not been received. In an embodiment of the present disclosure, when NACK is to be sent for each SRS resource ID, the second BS 20 may send NACK by adding information about resources that allow SRS listening to the NACK. When the first BS 20 is able to configure the UE with resources that allow the second BS 20 to listen to the SRS, the first BS 10 may send an RRC message requesting an SRS configuration change to the UE. After sending the RRC message, the first BS 10 may send a listening request to the second BS 20 based on the changed SRS configuration.

[0113] In operation S460, the second BS 20 may perform sensing on the SRS transmitted by the UE 30 to the first BS 10. The second BS 20 may measure a signal received in the SRS resource identified based on the sensing configuration information. In addition, the sensing configuration information may include, for example, information on a cyclic shift value for SRS generation, and based on this, the second BS 20 may identify the SRS. However, this is merely an example, and the sensing configuration information may include the information described above in conjunction with Figure 2 The second BS 20 may estimate the channel between the second BS 20 and the UE 30 by signal measurement. For example, the second BS 20 may estimate the UL channel by measuring the SINR, RSSI, and path loss degree of the received signal. In addition, the second BS 20 may estimate the DL channel based on the UL channel estimated by SRS listening.

[0114] In an embodiment of the present disclosure, when the distance between the first BS 10 and the second BS 20 is less than a specific distance, the second BS 20 may always perform an SRS listening operation for the UE 30 without being requested by the first BS 10. For example, the second BS 20 may perform an SRS listening operation at specific intervals without being requested by the first BS 10.

[0115] The second BS 20 may determine the MCS level and the number of layers suitable for the channel state of the UE based on the estimated UL channel information before starting or completing the handover procedure with the UE 30. In addition, the second BS 20 may minimize performance degradation from the handover by performing at least one of precoding matrix determination, UL frequency selective scheduling, or power control based on the estimated UL channel information.

[0116] Meanwhile, the SRS signal used for UL channel estimation by the second BS 20 is transmitted by considering the time domain synchronization between the UE 30 and the first BS 10. Therefore, due to the position difference between the UE 30 and the first BS 10 and between the UE 30 and the second BS 20, the SRS signal of the UE 30 received by the second BS 20 may not be synchronized. In order to solve the synchronization problem, the listening configuration information may include the position information of the UE 30. The second BS 20 can estimate the channel more accurately by synchronizing the SRS signal of the UE 30 received by the second BS 20 based on the position information of the UE 30. In an embodiment of the present disclosure, the listening configuration information may include time offset information considering the position between the second BS 20 and the UE 30. The first BS 10 can provide a time offset value to be considered for decoding the SRS signal received by the second BS 20 from the UE 30 by considering the position of the UE 30 and the second BS 20. However, this is only an example, and the position information or time offset information of the UE 30 can be provided separately from the listening configuration information.

[0117] In operation S470, the first BS 10 may send a handover command to the UE 30. For example, the first BS 10 may trigger the handover by sending an RRC reconfiguration message to the UE 30. The handover command may include information for accessing the second BS 20, which is received as a response to the handover request.

[0118] In operation S480, the UE 30 may perform handover from the first BS 10 to the second BS 20. The procedure for performing the handover may include the UE 30 sending a random access preamble to the second BS 20 and acquiring synchronization, and the second BS 20, upon receiving the random access preamble, sending a message including UL radio resources and time alignment (TA) information in a random access response.

[0119] In operation S490, the UE 30 completes the handover from the first BS 10 to the second BS 20. According to the handover, the serving BS of the UE 30 may be changed from the first BS 10 to the second BS 20. The UE 30 may send an RRC reconfiguration completion message to the second BS 20 after successfully connecting to the second BS 20. The second BS 20 configured to perform periodic SRS listening for the UE 30 may not perform the SRS listening operation for the UE 30 after receiving the RRC reconfiguration completion message. However, this is only an example, and the second BS 20 configured to perform periodic SRS listening for the UE 30 may not perform the SRS listening operation from the start of the handover.

[0120] The SRS-based listening operation according to the present disclosure can be applied to Rach-free switching. Figure 5 Let's describe it in more detail.

[0121] Figure 5 FIG. 1 is a flowchart showing the application of SRS-based fast link adaptation to RACH-free switching according to an embodiment of the present disclosure. Figure 4 The operations shown in .

[0122] refer to Figure 5 With RACH-less handover, the UE 30 can connect to the second BS 20 without random access because the UE 30 knows the TA value, unlike conventional handover.

[0123] In operation S510, the first BS 10 may send a first RRC reconfiguration message to the UE 30. The first RRC reconfiguration message may include information about the SRS configuration. The UE 30 may send an SRS to the first BS 10 based on the information about the SRS configuration (as described above in conjunction with Figure 2 describe).

[0124] In operation S520, the first BS 10 may send a second RRC reconfiguration message to the UE 30. In an embodiment of the present disclosure, the second RRC reconfiguration message may include MR configuration information of an event related to RACH-free switching.

[0125] In operation S530, the UE 30 may send an MR corresponding to the second RRC message to the first BS 10. In an embodiment of the present disclosure, after detecting an event regarding RACH-free switching, the UE 30 may send an MR corresponding to the event used in the MR configuration information to the first BS 10. In an embodiment of the present disclosure, the MR corresponding to the event may include signal strength and quality of the first BS 10 and the second BS 20.

[0126] In operation S540, the first BS 10 may transmit a handover request to the second BS 20. Upon receiving the MR corresponding to the detected event, the first BS 10 may transmit a handover request to a target for handover, which is the second BS 20.

[0127] In an embodiment of the present disclosure, the handover request message may include a transparent RRC container, which includes the handover preparation information and the ID of the second BS 20 and other information.

[0128] In an embodiment of the present disclosure, a handover request may include a request for SRS listening. The request for SRS listening may include information indicating the activation of SRS listening and information for configuring SRS listening. In an embodiment of the present disclosure, the listening request may be included in a transparent RRC container accompanying the handover request, or delivered vendor-specifically. For example, a request for SRS listening may be configured via the "RRC:srs-Config setup" IE in an RRC message. An example of the information included in the "RRC:srs-Config setup" IE is shown in Table 5. The "RRC:srs-Config:setup" IE may include an srs-ResourcesetId representing a resource ID, an srs-ResouceList representing a resource list included in the resource ID, and a resouceType representing a signal type for each SRS resource. For example, when srs-ResoucesetId is 1, the resource list may include 1, 2, 3, and 4, and the resource signal type may include periodic SRS.

[0129] Table 5.RRC: srs-Config setup IE

[0130]

[0131] In operation S550, the second BS 20 may send a response to the handover request to the first BS 10. The second BS 20 may receive the handover request and send an ACK or NACK to the handover request. In operation S560, the second BS 20 may perform listening on the SRS sent by the UE 30 to the first BS 10. When the second BS 20 sends an ACK, the second BS 20 may measure a signal received in an SRS resource identified based on the listening configuration information. In addition, the listening configuration information may include, for example, information about a cyclic shift value for SRS generation, and based on this, the second BS 20 may identify the SRS. However, this is merely an example, and the listening configuration information may include information as described above in combination with the SRS resource. Figure 2 One or more pieces of information included in the described SRS configuration information.

[0132] The second BS 20 can estimate the channel between the second BS 20 and the UE 30 through signal measurement. For example, the second BS 20 can estimate the UL channel by measuring the SINR, RSSI and path loss of the received signal. In an embodiment of the present disclosure, the second BS 20 can estimate the DL channel based on the UL channel estimated through SRS listening.

[0133] In operation S570, the first BS 10 may send a handover command to the UE 30. The first BS 10 may trigger the handover by sending an RRC reconfiguration message to the UE 30.

[0134] The second BS 20 may determine the MCS level and the number of layers suitable for the channel state of the UE based on the estimated UL channel information before starting or completing the handover process with the UE 30. In addition, the second BS 20 may minimize performance degradation from the handover by performing precoding matrix determination, UL frequency selective scheduling, and power control based on the estimated UL channel information.

[0135] In operation S580 , the second BS 20 may transmit a UL grant and TA information to the UE 30 .

[0136] In operation S590, the UE 30 completes handover from the first BS 10 to the second BS 20. Through the handover, the UE 30 becomes a UE served by the second BS 20. In an embodiment of the present disclosure, the UE 30 may send an RRC reconfiguration complete message to the second BS 20 after successfully connecting to the second BS 20.

[0137] Figure 6 A flowchart showing the application of SRS-based fast link adaptation to conditional switching according to an embodiment of the present disclosure is shown; for the sake of brevity, the details of the Figure 4 The operations shown in .

[0138] refer to Figure 6 , for conditional handover, UE 30 can determine whether to handover. Before entering a state where handover can be used, UE 30 can receive a message for handover from at least one second BS (BS-2a and BS-2b) 20a and 20b. For the second BS 20b that meets the condition for conditional handover, UE 30 can complete the handover without an additional instruction from the first BS 10.

[0139] In operation S610, the first BS 10 may send a first RRC reconfiguration message to the UE 30. The first RRC reconfiguration message may include configuration information of the SRS. In an embodiment of the present disclosure, the UE 30 may send the SRS to the first BS 10 as a response to the configuration information of the SRS.

[0140] In operation S615, the first BS 10 may send a second RRC reconfiguration message to the UE 30. In an embodiment of the present disclosure, the second RRC reconfiguration message may include MR configuration information regarding an event of conditional handover.

[0141] In operation S620, the UE 30 may send an MR corresponding to the second RRC message to the first BS 10. In an embodiment of the present disclosure, after detecting an event regarding conditional handover, the UE 30 may send an MR corresponding to the event used in the MR configuration information to the first BS 10. In an embodiment of the present disclosure, the MR corresponding to the event may include signal strength and quality of the first BS 10 and at least one second BS 20a and 20b.

[0142] In an embodiment of the present disclosure, the MR for conditional handover may include information on at least one second BS 20a and 20b that is a candidate for conditional handover.

[0143] In operation S625, the first BS 10 may send a handover request to the BS-2a 20a. In an embodiment of the present disclosure, the handover request message may include a transparent RRC container including the handover preparation information RRC message and the ID of the second BS 20 and other information.

[0144] In an embodiment of the present disclosure, the handover request may include a request for SRS listening. The request for SRS listening may include information indicating the activation of SRS listening and information for configuring SRS listening. In an embodiment of the present disclosure, the listening request may be included in a transparent RRC container accompanying the handover request, or delivered vendor-specifically. For example, the request for SRS listening may be configured via the "RRC: srs-Config setup" IE in the RRC message. In an embodiment of the present disclosure, the request for SRS listening may determine whether to perform listening for each SRS resource.

[0145] In operation S630, the BS-2a 20a may transmit a response to the handover request to the first BS 10. The BS-2a 20a may receive the handover request and transmit ACK or NACK for the handover request.

[0146] In operation S635, BS-2a 20a can perform sensing for the SRS transmitted by UE 30 to the first BS 10. When BS-2a 20a transmits ACK, BS-2a 20a can measure the signal received in the SRS resource identified based on the sensing configuration information. In addition, the sensing configuration information may include, for example, information on a cyclic shift value for SRS generation, and based on the information, the second BS 20 may identify the SRS. However, this is merely an example, and the sensing configuration information may include the above-mentioned information in combination with the SRS resource. Figure 2 One or more pieces of information included in the described SRS configuration information.

[0147] BS-2a 20a can estimate the channel between BS-2a 20a and UE 30 through signal measurement. For example, BS-2a 20a can estimate the UL channel by measuring SINR, RSSI and path loss of the received signal. In an embodiment of the present disclosure, BS-2a 20a can estimate the DL channel based on the UL channel estimated through SRS listening.

[0148] In operation S640, the first BS 10 may send a handover request to the BS-2b 20b. In an embodiment of the present disclosure, the handover request message may include a transparent RRC container including the handover preparation information RRC message and the ID of the second BS 20 and other information.

[0149] In an embodiment of the present disclosure, the handover request may include a request for SRS listening. The request for SRS listening may include information indicating the activation of SRS listening and information for configuring SRS listening. In an embodiment of the present disclosure, the listening request may be included in a transparent RRC container accompanying the handover request, or delivered vendor-specifically. For example, the request for SRS listening may be configured via the "RRC: srs-Config setup" IE in the RRC message. In an embodiment of the present disclosure, the request for SRS listening may determine whether to perform listening for each SRS resource.

[0150] In operation S645, the BS-2b 20b may transmit a response to the handover request to the first BS 10. The BS-2a 20a may receive the handover request and transmit ACK or NACK for the handover request.

[0151] In operation S650, BS-2b 20b can perform sensing on the SRS transmitted by UE 30 to the first BS 10. When BS-2b 20b transmits ACK, BS-2b 20b can measure the signal received in the SRS resource identified based on the sensing configuration information. In addition, the sensing configuration information may include, for example, information on a cyclic shift value for SRS generation, and based on this, the second BS 20 may identify the SRS. However, this is merely an example, and the sensing configuration information may include information as described above in conjunction with Figure 2 One or more pieces of information included in the described SRS configuration information.

[0152] BS-2b 20b can estimate the channel between BS-2b 20b and UE 30 through signal measurement. For example, BS-2b 20b can estimate the UL channel by measuring SINR, RSSI and path loss of the received signal. In an embodiment of the present disclosure, BS-2b 20b can estimate the DL channel based on the UL channel estimated through SRS listening.

[0153] In operation S655, the first BS 10 may send a third RRC reconfiguration message to the UE 30. The third RRC reconfiguration message includes configuration information about conditional handover. In an embodiment of the present disclosure, the configuration information about conditional handover may include RRC measurement configuration to help find the most suitable one of the at least one second BS 20a and 20b that can be used for handover.

[0154] BS-2a 20a can determine the MCS level and the number of layers suitable for the channel state of the UE before starting or completing the handover process with the UE 30 based on the estimated UL channel information. In addition, BS-2a 20a can minimize performance degradation from handover by performing precoding matrix determination, UL frequency selective scheduling, and power control based on the estimated UL channel information.

[0155] In operation S660 , the UE 30 may transmit a message indicating that the RRC configuration is completed to the first BS 10 .

[0156] In operation S665, the UE 30 may determine and perform conditional handover. In an embodiment of the present disclosure, the UE 30 may determine whether a condition is satisfied according to the third RRC reconfiguration message, and determine one of at least one second BS 20a and 20b that best suits the condition. The UE 30 may perform handover to the BS-2b 20b based on the determination of conditional handover.

[0157] In operation S670, the UE 30 completes handover from the first BS 10 to the second BS 20. Through the handover, the UE 30 becomes a UE served by the second BS 20. In an embodiment of the present disclosure, the UE 30 may send an RRC reconfiguration complete message to the second BS 20 after successfully connecting to the second BS 20.

[0158] Figure 7 A flowchart for describing transmission of an additional message for SRS listening in SRS-based fast link adaptation according to an embodiment of the present disclosure is shown; for the sake of brevity, the details of the additional message will not be described in detail. Figure 4 The operations shown in .

[0159] In operation S710, the first BS 10 may transmit MR configuration information to the UE 30. When an event is detected based on the MR configuration information in S715, the UE 30 transmits an MR corresponding to the event to the first BS 10 in S720. In an embodiment of the present disclosure, the event may include an event regarding handover, an event regarding SRS listening, or an event regarding multi-TRP configuration.

[0160] In operation S725, the first BS 10 may send an SRS listening request to the second BS 20. In an embodiment of the present disclosure, the request for SRS listening may include information indicating activation of SRS listening and information for configuring SRS listening. For example, the request for SRS listening may be configured by the "RRC: srs-Config setup" IE in the RRC message. In an embodiment of the present disclosure, the first BS 10 may indicate whether listening is used for each SRS resource. Information about resources and resource IDs used for SRS listening may be sent in a transparent container, an additional container, or a field accompanying the listening request.

[0161] In operation S730, the second BS 20 may transmit an SRS listening response to the first BS 10. The second BS 20 may transmit ACK or NACK as a response to the SRS listening request.

[0162] In an embodiment of the present disclosure, when SRS resource information for sounding and SRS resource information of a UE served by the second BS 20 conflict with each other or when the second BS 20 has no room for PHY processing capability, the second BS 20 may transmit NACK for the SRS sounding request.

[0163] In an embodiment of the present disclosure, the second BS 20 may respond to a listening request for each SRS resource ID. The response to the listening request may be represented by using a bitmap corresponding to the SRS resource ID. In an embodiment of the present disclosure, the second BS 20 may not respond to a resource for which an SRS listening request has not been received. In an embodiment of the present disclosure, when NACK is to be sent for each SRS resource ID, the second BS 20 may add information about resources that allow SRS listening to the NACK and send the NACK. When the first BS 20 is able to configure a resource that allows the second BS 20 to listen to SRS for the UE, the first BS 10 may send an RRC message requesting an SRS configuration change to the UE. After sending the RRC message, the first BS 10 may send a listening request to the second BS 20 based on the changed SRS configuration.

[0164] In operation S735, the second BS 20 may perform sensing on the SRS transmitted by the UE 30 to the first BS 10. When the second BS 20 transmits ACK, the second BS 20 may measure the signal received in the SRS resource identified based on the sensing configuration information. In addition, the sensing configuration information may include, for example, information on a cyclic shift value for SRS generation, and based on the information, the second BS 20 may identify the SRS. However, this is merely an example, and the sensing configuration information may include the information described above in conjunction with Figure 2 One or more pieces of information included in the described SRS configuration information.

[0165] The second BS 20 can estimate the channel between the second BS 20 and the UE 30 through signal measurement. For example, the second BS 20 can estimate the UL channel by measuring the SINR, RSSI and path loss of the received signal. In an embodiment of the present disclosure, the second BS 20 can estimate the DL channel based on the UL channel estimated through SRS listening.

[0166] The second BS 20 may determine the MCS level and the number of layers suitable for the channel state of the UE based on the estimated UL channel information before starting or completing the handover procedure with the UE 30. In addition, the second BS 20 may minimize performance degradation from the handover by performing precoding matrix determination, UL frequency selective scheduling, and power control based on the estimated UL channel information.

[0167] In an embodiment of the present disclosure, the second BS 20 may collect UL channel state information (CSI) by listening to the SRS. In an embodiment of the present disclosure, the second BS 20 may send a message indicating completion of collecting UL CSI to the first BS 10.

[0168] In operation S740, the first BS 10 may send a handover request to the second BS 20. In an embodiment of the present disclosure, the handover request may be configured with an RRC:srs-Config setup IE. In an embodiment of the present disclosure, the handover request message may include a transparent RRC container including a handover preparation information RRC message and an ID of the second BS 20 and other information.

[0169] In an embodiment of the present disclosure, the handover request may include resource information for handover. The resource information for handover may include other information depending on the handover type. For example, the handover may include RACH-free handover, conditional handover (CHO), dual active protocol stack (DAPS) handover, etc.

[0170] In operation S745, the second BS 20 may transmit a response to the handover request to the first BS 10. The second BS 20 may receive the handover request and transmit ACK or NACK for the handover request.

[0171] In an embodiment of the present disclosure, the response to the handover request may include a message indicating that the collection of UL CSI through SRS sensing is completed.

[0172] In operation S750, the first BS 10 may send a handover command to the UE 30. The first BS 10 may trigger the handover by sending an RRC reconfiguration message to the UE 30.

[0173] In an embodiment of the present disclosure, the handover command may include information for accessing the second BS 20, which is received as a response to the handover request.

[0174] In operation S755, the UE 30 may perform handover from the first BS 10 to the second BS 20. The procedure for performing handover may include the UE 30 transmitting a random access preamble to the second BS 20 and synchronizing, and the second BS 20 transmitting a message including UL radio resources and TA information in a random access response upon receiving the random access preamble.

[0175] In operation S760, the UE 30 completes handover from the first BS 10 to the second BS 20. Through the handover, the UE 30 becomes a UE served by the second BS 20. In an embodiment of the present disclosure, the UE 30 may send an RRC reconfiguration complete message to the second BS 20 after successfully connecting to the second BS 20.

[0176] Figure 8 A flowchart for describing multiple events in SRS-based fast link adaptation according to an embodiment of the present disclosure is shown. In an embodiment of the present disclosure, the event may include a first event about listening and a second event about switching. For the sake of brevity, the events related to the first event and the second event about switching will not be described in detail. Figure 7 The operations shown in .

[0177] In operation S810, the first BS 10 may transmit at least one piece of MR configuration information to the UE 30. In an embodiment of the present disclosure, the at least one piece of MR configuration information may include MR configuration information about a first event of interception and MR configuration information about a second event of handover.

[0178] In operation S815, the UE 30 may detect a first event regarding interception. In an embodiment of the present disclosure, the first event regarding interception may have a smaller offset value than a second event regarding handover.

[0179] In operation S820, the UE 30 may transmit the MR corresponding to the first event to the first BS 10. Upon detecting the first event, the UE 30 transmits the MR corresponding to the event used in the MR configuration information.

[0180] In an embodiment of the present disclosure, the MR corresponding to the event may include information on signal strength and quality of the first BS 10 and the second BS 20. For example, the MR may include information on RSRP, RSRQ, SINR, and PCI.

[0181] In operation S825, the first BS 10 may send an SRS listening request to the second BS 20. In an embodiment of the present disclosure, the request for SRS listening may include information indicating activation of SRS listening and information for configuring SRS listening. For example, the request for SRS listening may be configured by the "RRC:srs-Config setup" IE in the RRC message. In an embodiment of the present disclosure, the first BS 10 may indicate whether listening is used for each SRS resource. In an embodiment of the present disclosure, information about resources and resource IDs used for SRS listening may be sent in a transparent container, an additional container, or a field accompanying the listening request.

[0182] In operation S830, the second BS 20 may transmit an SRS listening response to the first BS 10. The second BS 20 may transmit ACK or NACK as a response to the SRS listening request.

[0183] In operation S835, the second BS 20 may perform sensing on the SRS transmitted by the UE 30 to the first BS 10. When the second BS 20 transmits ACK, the second BS 20 may measure the signal received in the SRS resource identified based on the sensing configuration information. In addition, the sensing configuration information may include, for example, information on a cyclic shift value for SRS generation, and based on the information, the second BS 20 may identify the SRS. However, this is merely an example, and the sensing configuration information may include the above-mentioned information in combination with the SRS resource. Figure 2 One or more pieces of information included in the described SRS configuration information.

[0184] The second BS 20 can estimate the channel between the second BS 20 and the UE 30 through signal measurement. For example, the second BS 20 can estimate the UL channel by measuring the SINR, RSSI and path loss of the received signal. In an embodiment of the present disclosure, the second BS 20 can estimate the DL channel based on the UL channel estimated through SRS listening.

[0185] The second BS 20 may determine the MCS level and the number of layers suitable for the channel state of the UE based on the estimated UL channel information before starting or completing the handover procedure with the UE 30. In addition, the second BS 20 may minimize performance degradation from the handover by performing precoding matrix determination, UL frequency selective scheduling, and power control based on the estimated UL channel information.

[0186] In operation S840, the UE 30 may detect a second event regarding handover.

[0187] In operation S845, the UE 30 transmits the MR corresponding to the second event to the first BS 10. Upon detecting the second event, the UE 30 transmits the MR corresponding to the event used in the MR configuration information.

[0188] In operation S850, the first BS 10 may send a handover request to the second BS 20. In an embodiment of the present disclosure, the handover request may be configured with an RRC:srs-Config setup IE. In an embodiment of the present disclosure, the handover request message may include a transparent RRC container including a handover preparation information RRC message and an ID of the second BS 20 and other information.

[0189] In operation S855, the second BS 20 may transmit a response to the handover request to the first BS 10. The second BS 20 may receive the handover request and transmit ACK or NACK for the handover request.

[0190] In operation S860, the first BS 10 may send a handover command to the UE 30. The first BS 10 may trigger the handover by sending an RRC reconfiguration message to the UE 30.

[0191] In operation S865, the UE 30 may perform handover from the first BS 10 to the second BS 20. The procedure for performing handover may include the UE 30 transmitting a random access preamble to the second BS 20 and synchronizing, and the second BS 20 transmitting a message including UL radio resources and TA information in a random access response upon receiving the random access preamble.

[0192] In operation S870, the UE 30 completes handover from the first BS 10 to the second BS 20. Through the handover, the UE 30 becomes a UE served by the second BS 20. In an embodiment of the present disclosure, the UE 30 may send an RRC reconfiguration complete message to the second BS 20 after successfully connecting to the second BS 20.

[0193] Fig. 9 FIG. 1 is a flowchart for describing additional transmission of an SRS configuration message in SRS-based fast link adaptation according to an embodiment of the present disclosure. Except for operation 930 which will now be described, it is similar to FIG. Figure 6 and Figure 8 Those.

[0194] In operation S930, the first BS 10 may transmit a third RRC reconfiguration message to the UE 30. In an embodiment of the present disclosure, the third RRC reconfiguration message may include SRS configuration information.

[0195] In an embodiment of the present disclosure, the third RRC reconfiguration message may be sent in operation S930 when the first RRC reconfiguration message is not sent in operation S910. In an embodiment of the present disclosure, the timing when the first RRC reconfiguration message is not sent may include a timing when SRS does not need to be pre-configured and a timing when beamforming based on a precoding matrix indication (PMI) is used.

[0196] In an embodiment of the present disclosure, when the SRS configured with the first RRC reconfiguration message has a long period, a third RRC reconfiguration message may be sent. In an embodiment of the present disclosure, when the SRS has a long period, the second BS 20 may not collect enough UL CSI for use with the SRS signal between operation S940 and operation S980. In an embodiment of the present disclosure, the third RRC reconfiguration message may adjust the transmission period of the SRS to be shorter in order to collect enough UL CSI.

[0197] Fig.10 A diagram for describing multiple TRPs to which SRS-based sensing is applied according to an embodiment of the present disclosure is shown. In some embodiments of the present disclosure for describing operations related to configuration of multiple TRPs, the first BS 10 and the second BS 20 are referred to as TRP A and TRP B, respectively.

[0198] refer to Fig.10 , multiple TRPs may be configured for UE 30 to receive data from both BS 10 and 20. TRP A10 and TRPB 20 may have the same PCI or different PCIs. In an embodiment of the present disclosure, when multiple TRPs are configured, not only the first BS 10 but also the second BS 20 may send an SRS transmission command to UE 30. In an embodiment of the present disclosure, when switching is expected, the second BS 20 instead of the first BS 10 may directly send an SRS transmission request to UE 30. UE 30 may send an SRS to the second BS 20 in response to the SRS transmission request. The second BS 20 may receive the SRS and estimate the channel between UE 30 and the second BS 20. Using the estimated channel, the second BS 20 may perform a fast link adaptation method immediately after switching.

[0199] In an embodiment of the present disclosure, when multiple TRPs are configured, UE 30 traditionally performs UL communication with TRP A 10 and TRP B 20 using uplink control information (UCI) (on a physical uplink control channel (PUCCH)), and performs DL communication using downlink control information (DCI) (on a physical downlink control channel). In the present disclosure, UE 30 can perform DL communication with TRP B 20 using DCI (on PDCCH), MAC CE, or RRC through fast link adaptation.

[0200] In an embodiment of the present disclosure, in case of communication between UE 30 and TRP B 20 using MAC CE, UE 30 may transmit a semi-persistent SRS, and in case of communication using PDCCH DCI, UE 30 may transmit an aperiodic SRS.

[0201] Fig.11 FIG. 1 is a diagram showing an example of applying an SRS-based fast link adaptation method to a base station (BS) configured with multiple TRPs according to an embodiment of the present disclosure. Figure 8 The operations shown in .

[0202] In operation S1110, the first BS 10 may transmit a first RRC reconfiguration message to the UE 30. The first RRC reconfiguration message may include SRS configuration information.

[0203] In operation S1115, the first BS 10 may send a second RRC reconfiguration message to the UE 30. In an embodiment of the present disclosure, the second RRC reconfiguration message may include at least one MR configuration information. In an embodiment of the present disclosure, the at least one MR configuration information may include MR configuration information about a first event of multi-TRP configuration and MR configuration information about a second event related to handover.

[0204] In an embodiment of the present disclosure, the MR configuration information of the first event regarding the multi-TRP configuration may include information for determining whether the second BS 20 is registered in multiple TRPs before switching.

[0205] In operation S1120, the UE 30 may detect a first event regarding a multi-TRP configuration. In an embodiment of the present disclosure, the first event regarding the multi-TRP configuration may have a smaller offset value than a second event regarding a switch.

[0206] In operation S1125, the UE 30 may transmit the MR corresponding to the first event to the first BS 10. Upon detecting the first event, the UE 30 transmits the MR corresponding to the event used in the MR configuration information.

[0207] In an embodiment of the present disclosure, the MR corresponding to the event may include information on signal strength and quality of the first BS 10 and the second BS 20. For example, the MR may include information on RSRP, RSRQ, SINR, and PCI.

[0208] In operation S1130, the first BS 10 may transmit the multi-TRP configuration information to the UE 30. In an embodiment of the present disclosure, the information for configuring the multiple TRPs may include information about the TRP B 20.

[0209] In operation S1135, the UE 30 may send a response to the first BS 10a upon receiving the multi-TRP configuration information. In an embodiment of the present disclosure, the response to the multi-TRP configuration information may include a response on whether to add TRP B 20 to multiple TRPs for the UE 30 before handover.

[0210] In operation S1140, the first BS 10 may send UE information and a fast link adaptation request to the second BS 20. In an embodiment of the present disclosure, the request message may include a message indicating that a plurality of TRPs are registered for SRS listening. In an embodiment of the present disclosure, the request message may include a message indicating that SRS may be received from the UE 30 immediately after the handover for fast link adaptation.

[0211] In operation S1145, the second BS 20 may trigger SRS transmission for the UE 30. In an embodiment of the present disclosure, just after the handover, the second BS 20 may receive SRS from the UE 30 for fast link adaptation. In an embodiment of the present disclosure, the second BS 20 may directly send an SRS transmission request to the UE 30.

[0212] In an embodiment of the present disclosure, the second BS 20 may trigger SRS transmission through MAC CE, DCI or RRC. In an embodiment of the present disclosure, when the second BS 20 triggers SRS transmission through MAC CE, semi-persistent SRS may be triggered. When the second BS 20 triggers SRS transmission through DCI, aperiodic SRS may be triggered. When the second BS 20 triggers SRS transmission through RRC, periodic SRS may be triggered.

[0213] In operation S1150, the UE 30 may transmit the SRS to the second BS 20. In an embodiment of the present disclosure, the first BS 10 may not receive the SRS transmitted by the UE 30 to the second BS 20.

[0214] In operation S1155 , the second BS 20 may directly receive the SRS from the UE 30 .

[0215] In operation S1160 , the UE 30 may detect a second event regarding handover.

[0216] In operation S1165, the UE 30 transmits the MR corresponding to the second event to the first BS 10. Upon detecting the second event, the UE 30 transmits the MR corresponding to the event used in the MR configuration information.

[0217] In operation S1170, the first BS 10 may send a handover request to the second BS 20. In an embodiment of the present disclosure, the handover request may be configured with an RRC:srs-Config setup IE. In an embodiment of the present disclosure, the handover request message may include a transparent RRC container including a handover preparation information RRC message and an ID of the second BS 20 and other information.

[0218] In operation S1175, the second BS 20 may transmit a response to the handover request to the first BS 10. The second BS 20 may receive the handover request and transmit ACK or NACK for the handover request.

[0219] In operation S1180, the first BS 10 may transmit a handover command to the UE 30. The first BS 10 may trigger the handover by transmitting an RRC reconfiguration message to the UE 30.

[0220] In operation S1185, UE 30 may perform handover from the first BS 10 to the second BS 20. The procedure for performing handover may include UE 30 transmitting a random access preamble to the second BS 20 and synchronizing, and the second BS 20 transmitting a message including UL radio resources and TA information in a random access response upon receiving the random access preamble.

[0221] In operation S1190, the UE 30 completes handover from the first BS 10 to the second BS 20. Through the handover, the UE 30 becomes a UE served by the second BS 20. In an embodiment of the present disclosure, the UE 30 may send an RRC reconfiguration complete message to the second BS 20 after successfully connecting to the second BS 20.

[0222] Fig. 12A and Fig. 12B A diagram for describing a change trend of a transmission rate in a case where an SRS-based fast link adaptation method is performed according to an embodiment of the present disclosure is shown.

[0223] Fig. 12AA diagram showing a transmission rate according to a switch from a first BS10 to a second BS20 is shown. In an embodiment of the present disclosure, in a state connected to the first BS10, the transmission rate is 600 megabits per second (Mbps). During a period 1210 of switching from the first BS10 to the second BS20, the data transmission rate drops to 0 Mbps. In an embodiment of the present disclosure, throughput degradation occurs due to a switching interruption time just after the switch. In an embodiment of the present disclosure, since the UE 30 cannot perform data transmission or reception while performing a RACH operation, throughput degradation 1210 may occur just after the switch. The throughput degradation 1210 caused by the RACH operation can be enhanced by research to minimize the random access process, and, for example, DAPS or 2-step RACH can be used.

[0224] In an embodiment of the present disclosure, after the handover is completed, the throughput degradation section 1220 occurs due to the robust MCS / layer allocation. In an embodiment of the present disclosure, as the channel information between the UE 30 and the second BS 20 is unknown, the throughput degradation section 1220 caused by the MCS / layer allocation may occur due to the robust MCS / layer allocation.

[0225] Fig. 12B FIG. 1 is a diagram showing a conventional trend 1230 for comparing throughput degradation with a throughput degradation trend 1240 according to the present disclosure as a UE 30 performs a handover from a first BS 10 to a second BS 20. Fig. 12A In the embodiment of the present disclosure, the trend 1240 of throughput degradation according to the present disclosure corresponds to the conventional trend 1230 of throughput degradation in the throughput degradation section 1210 caused by RACH operation. In the throughput degradation section 1220 caused by allocation of the number of robust MCS levels and layers, the trend 1240 of the present disclosure shows a faster transmission rate recovery than the conventional trend 1230.

[0226] In an embodiment of the present disclosure, trend 1240 of the present disclosure shows that as the second BS 20 performs sensing on the SRS transmitted by the UE 30 to the first BS 10, the UL channel can be estimated and UL adaptation is possible. For example, UL channel estimation can be performed by measuring SINR, RSSI and path loss of the uplink.

[0227] In an embodiment of the present disclosure, trend 1240 of the present disclosure shows that due to time division duplex (TDD) reciprocity, the UL channel can be used to estimate the DL channel. DL adaptation is possible on the estimated DL channel. For example, DL channel estimation can be performed by obtaining the rank of DL, the channel matrix, and the estimated DL SINR. In an embodiment of the present disclosure, for the rank of DL, in the case of SRS transmission based on transmit antenna selection (TAS), the rank value can be tracked by the BS identifying the channel information from each antenna.

[0228] When the UL channel and the DL channel between the UE 30 and the second BS 20 are estimated, the second BS 20 may perform fast link adaptation by allocating an appropriate number of MCS levels and layers.

[0229] Fig.13 A block diagram schematically illustrating a configuration of a UE according to an embodiment of the present disclosure is shown.

[0230] refer to Fig.13 , UE 1300 may include a processor 1310, a transceiver 1320, and a memory (not shown). However, the elements of UE 1300 are not limited thereto. For example, UE 1300 may include more or fewer elements than described above. In an embodiment of the present disclosure, the processor 1310, the memory, and the transceiver 1320 may be implemented in a single chip.

[0231] The processor 1310 may include one or more processors. The one or more processors may be a central processing unit (CPU), an application processor (AP), a digital signal processor (DSP), and the like.

[0232] The processor 1310 may control a series of processes of the UE 1300 to be operated according to the aforementioned embodiments of the present disclosure. For example, the processor 1310 may receive a control signal and a data signal through the transceiver 1320, and process the received control signal and data signal. The processor 1310 may send the processed control signal and data signal through the transceiver 1320, and detect an event. In addition, the processor 1310 may control the input data derived from the received control signal and data signal to be processed according to a predefined operation rule or an artificial intelligence (AI) model stored in the memory. The processor 1310 may record data to the memory or read data from the memory. The processor 1310 may also perform the functions of the protocol stack requested by the communication standard. In an embodiment of the present disclosure, the processor 1310 may include at least one processor. In an embodiment of the present disclosure, a part of the transceiver 1320 or the processor 1310 may be referred to as a communication processor (CP).

[0233] The memory may store programs and data for the operation of UE 1300. In addition, the memory may store control information or data included in the signal obtained by UE 1300. In addition, the memory may store predefined operating rules or AI models used by UE 1300. The memory may include a storage medium such as a read-only memory (ROM), a random access memory (RAM), a hard disk, a compact disk (CD) ROM (CD-ROM) and a digital versatile disk (DVD), or a combination of storage media. Alternatively, the memory may not exist alone, but integrated into the processor 1310. The memory may include a volatile memory, a non-volatile memory, or a combination of a volatile memory and a non-volatile memory. The memory may also provide stored data at the request of the processor 1310.

[0234] The transceiver 1320 may indicate a transmitter and a receiver, and the transceiver 1320 of the UE 1300 may send a signal to a BS or a network entity or receive a signal from a BS or a network entity. The signal may include control information and data. To this end, the transceiver 1320 may include an RF transmitter and an RF receiver, wherein the RF transmitter is used to up-convert the frequency of the signal to be sent and amplify the signal, and the RF receiver is used to perform low-noise amplification on the received signal and down-convert the frequency of the received signal. It is only an example of the transceiver 1320, and the elements of the transceiver 1320 are not limited to the RF transmitter and the RF receiver. In addition, the transceiver 1320 may receive a signal on a wireless channel and output the signal to the processor 1310, and send a signal output from the processor 1310 on a wireless channel.

[0235] Fig.14 A schematic block diagram showing the configuration of a BS according to an embodiment of the present disclosure.

[0236] refer to Fig.14 , BS1400 may include a processor 1410, a transceiver 1420, and a memory (not shown). The transceiver 1420, the processor 1410, and the memory of BS1400 may operate according to the aforementioned communication method of BS1400. However, the elements of BS1400 are not limited thereto. For example, the base station 1400 may include more or less elements than those described above. In an embodiment of the present disclosure, the transceiver 1420, the processor 1410, and the memory may be implemented in a single chip. The processor 1410 may include one or more processors.

[0237] The processor 1410 may control a series of processes of the BS 1400 operated according to an embodiment of the present disclosure. For example, the processor 1410 may receive a control signal and a data signal through the transceiver 1420, and process the received control signal and data signal. The processor 1410 may send the processed control signal and data signal through the transceiver 1420. The processor 1410 may record data to a memory or read data from a memory. The processor 1410 may perform the functions of a protocol stack requested by a communication standard. To this end, the processor 1410 may include at least one processor or microprocessor. In an embodiment of the present disclosure, a portion of the transceiver 1420 and the processor 1410 may be referred to as a CP.

[0238] The processor 1410 may include one or more processors, which may be a CPU, an AP, a DSP, and the like.

[0239] The receiver and transmitter of BS1400 are collectively referred to as transceiver 1420, wherein transceiver 1420 can send or receive signals to or from UE or network entity. The signal to be sent or received to or from UE or network entity may include control information and data. To this end, transceiver 1420 may include an RF transmitter for up-converting the frequency of the signal to be sent and amplifying the signal and an RF receiver for low-noise amplification of the received signal and down-converting the frequency of the received signal. It is only an example of transceiver 1420, and the elements of transceiver 1420 are not limited to RF transmitter and RF receiver.

[0240] The transceiver 1420 may perform a function for transmitting and receiving a signal on a wireless channel. For example, the transceiver 1420 may receive a signal on a wireless channel and output the signal to the processor 1410, and transmit a signal output from the processor 1410 on a wireless channel.

[0241] The memory may store programs and data for the operation of the BS 1400. In addition, the memory may store control information or data included in a signal obtained by the BS. The memory may include a storage medium such as a ROM, a RAM, a hard disk, a CD-ROM, and a DVD, or a combination of storage media. Alternatively, the memory may not exist alone, but may be integrated into the processor 1410. The memory may include a volatile memory, a nonvolatile memory, or a combination of a volatile memory and a nonvolatile memory. The memory may also provide stored data at the request of the processor 1410.

[0242] The machine-readable storage medium may be provided in the form of a non-transitory storage medium. The term "non-transitory storage medium" may refer to a tangible device without including signals (e.g., electromagnetic waves), and may not distinguish between semi-permanent and temporary storage of data in the storage medium. For example, a non-transitory storage medium may include a buffer that temporarily stores data.

[0243] In an embodiment of the present disclosure, the aforementioned method according to various embodiments of the present disclosure may be provided in a computer program product. The computer program product may be a commercial product that can be traded between a seller and a buyer. The computer program product may be distributed in the form of a storage medium (e.g., a CD-ROM), through an application store, directly between two user devices (e.g., a smart phone), or online (e.g., downloading or uploading). In the case of online distribution, at least a portion of the computer program product (e.g., a downloadable app) may be at least temporarily stored or arbitrarily created in a storage medium, wherein the storage medium may be readable by a device such as a manufacturer's server, an application store's server, or a relay server.

[0244] According to an embodiment of the present disclosure, a fast link adaptation method may be provided through SRS sensing.

[0245] According to an embodiment of the present disclosure, a method for performing communication by a first base station (BS) in a wireless communication system is provided. The method includes: sending configuration information of at least one measurement report (MR) to a user equipment (UE) served by the first BS, receiving an MR associated with an event detected by the UE from the UE based on the configuration information of the at least one MR, and sending a first message including listening configuration information associated with a sounding reference signal (SRS) sent from the UE to the first BS to at least one second BS, wherein the listening configuration information is used for the at least one second BS to listen to the SRS.

[0246] According to an embodiment of the present disclosure, the listening configuration information may include at least one of antenna port information or time-frequency resource information in which the SRS for which listening is requested is sent, and at least one second BS that has received a first message including the listening configuration information may receive the SRS based on at least one of the time-frequency resource information or the antenna port information.

[0247] According to an embodiment of the present disclosure, the configuration information of the MR may include configuration information related to criteria for triggering events related to switching, and sending a first message including listening configuration information may include: when an MR corresponding to the event related to switching is received, sending a switching request message including listening configuration information to at least one second BS.

[0248] According to an embodiment of the present disclosure, the configuration information of the MR may include at least one of configuration information related to criteria for triggering events related to listening or configuration information related to criteria for triggering events related to switching, and sending a first message including the listening configuration information may include: when at least one of the MR corresponding to the event related to listening or the MR corresponding to the event related to switching is received, sending the first message including the listening configuration information to at least one second BS.

[0249] According to an embodiment of the present disclosure, the method may further include receiving a response to the listening configuration information from the at least one second BS, and sending a handover request message for the UE to the at least one second BS.

[0250] According to an embodiment of the present disclosure, the configuration information of the MR may include configuration information related to criteria for triggering an event for configuring multiple transmit-receive points (TRPs), and the method may further include: when the MR corresponding to the event for configuring multiple TRPs is received from the UE, sending the configuration information of multiple TRPs to the UE, and sending a fast link adaptation request message to at least one second BS, wherein the fast link adaptation request message includes information of the UE in which the event for configuring multiple TRPs occurs, and based on the fast link adaptation request message, when a control signal requesting SRS transmission is sent from the at least one second BS to the UE, SRS can be sent from the UE to the at least one second BS.

[0251] According to an embodiment of the present disclosure, a method for performing communication by a second BS in a wireless communication system is provided. The method includes: receiving a first message including listening configuration information of an SRS sent from a UE to the first BS from a first BS, sending a response message to the first BS in response to receiving the first message, and receiving the SRS based on the listening configuration information.

[0252] According to an embodiment of the present disclosure, the SRS listening configuration information may include at least one of antenna port information or time-frequency resource information in which the SRS for which listening is requested is sent, and the second BS may receive the SRS based on at least one of the time-frequency resource information or the antenna port information.

[0253] According to an embodiment of the present disclosure, the configuration information of the MR may include configuration information related to criteria for triggering events related to switching, and receiving a first message including listening configuration information may include: when the first BS receives an MR corresponding to an event related to switching, receiving a switching request message including listening configuration information.

[0254] According to an embodiment of the present disclosure, the configuration information of the MR may include at least one of configuration information related to criteria for triggering events related to listening or configuration information related to criteria for triggering events related to switching, and receiving a first message including the listening configuration information may include: when the first BS receives at least one of an MR corresponding to an event related to listening or an MR associated with an event related to switching, receiving the first message including the listening configuration information.

[0255] According to an embodiment of the present disclosure, the method may further include: sending a response to the listening configuration information to the first BS; and receiving a handover request message for the UE from the first BS.

[0256] According to an embodiment of the present disclosure, the method may further include transmitting information on at least one SRS resource to be received by the second BS and a negative acknowledgement (NACK) for the listening configuration information to the first BS when it is impossible to receive the SRS based on the listening configuration information.

[0257] According to an embodiment of the present disclosure, the configuration information of the MR may include configuration information related to the criteria for triggering a multi-TRP configuration event, and the method may also include: receiving a fast link adaptation request message including UE information based on the MR corresponding to the multi-TRP configuration event received by the first BS from the UE, sending a control signal requesting SRS transmission to the UE based on the fast link adaptation request message, and receiving SRS from the UE based on the control signal.

[0258] According to an embodiment of the present disclosure, a method for performing communication by a UE in a wireless communication system is provided. The method includes: receiving configuration information of at least one MR from a first BS as a serving BS, and when an event is detected based on the configuration information of the at least one MR, sending an MR associated with the event to the first BS, wherein a first message including the listening configuration information is received by at least one second BS from the first BS based on the received MR for switching, wherein the at least one second BS receives an SRS sent from the UE to the first BS based on the listening configuration information.

[0259] According to an embodiment of the present disclosure, a first BS for performing communication in a wireless communication system is provided. The first BS includes a transceiver and at least one processor coupled to the transceiver, wherein the at least one processor is configured to: send configuration information of at least one MR to a UE served by the first BS, when an event is detected by the UE based on the configuration information of the at least one MR, receive an MR corresponding to the event from the UE, and send listening configuration information of an SRS sent from the UE to the first BS to at least one second BS for handover, wherein the listening configuration information is used to estimate a channel state based on the SRS between the at least one second BS and the UE.

[0260] According to an embodiment of the present disclosure, a second BS for performing communication in a wireless communication system is provided. The second BS includes a transceiver and at least one processor coupled to the transceiver, wherein the at least one processor is configured to: in response to the first BS receiving an MR corresponding to an event from a UE based on an event detected by the UE served by the first BS based on configuration information of at least one MR, receive listening configuration information of an SRS sent from the UE to the first BS based on the received MR, receive the SRS based on the listening configuration information, and estimate the channel state between the UE and the second BS based on the received SRS.

[0261] According to an embodiment of the present disclosure, a UE for performing communication in a wireless communication system includes a transceiver and at least one processor coupled to the transceiver, wherein the at least one processor is configured to receive configuration information of at least one MR from a first BS serving as a service BS, and when an event is detected by the UE based on the configuration information of the at least one MR, send an MR corresponding to the event to the first BS, wherein listening configuration information is received by at least one second BS based on the received MR for switching from the first BS, wherein the at least one second BS receives an SRS sent from the UE to the first BS based on the listening configuration information, and wherein the channel state between the UE and the at least one second BS is estimated based on the SRS.

[0262] Although the present disclosure has been described with various embodiments, various changes and modifications may be suggested to one skilled in the art. The present disclosure is intended to encompass such changes and modifications as fall within the scope of the appended claims.

Claims

1. A method for performing communication by a first base station (BS) in a wireless communication system, the method comprising: Sending configuration information of at least one measurement report (MR) to a user equipment (UE) served by the first BS; receiving, from the UE, a MR associated with an event detected by the UE based on configuration information of the at least one MR; as well as sending a first message to at least one second BS, the first message including listening configuration information associated with a sounding reference signal (SRS) sent from the UE to the first BS, The listening configuration information is used by at least one second BS to listen to the SRS.

2. The method according to claim 1, wherein: The listening configuration information includes at least one of antenna port information and time-frequency resource information in which the SRS for which listening is requested is transmitted, and The at least one second BS that has received the first message including the listening configuration information receives the SRS based on at least one of the time-frequency resource information and the antenna port information.

3. The method according to claim 1, wherein: The configuration information of the MR includes configuration information related to criteria for triggering events related to handover, The sending of the first message including the interception configuration information includes: when the MR associated with the event related to the handover is received, sending a handover request message including the interception configuration information to at least one second BS.

4. The method according to claim 1, wherein: The configuration information of the MR includes at least one of configuration information related to a criterion for triggering an event related to interception and configuration information related to a criterion for triggering an event related to switching, and The sending of the first message including the interception configuration information includes: when at least one of the MR associated with the interception-related event and the MR associated with the handover-related event is received, sending the first message including the interception configuration information to at least one second BS.

5. The method according to claim 1, further comprising: receiving a response message to the listening configuration information from at least one second BS; as well as A handover request message for the UE is sent to at least one second BS.

6. The method according to claim 1, wherein: The configuration information of the MR includes configuration information related to criteria for triggering a multiple transmit-receive point (TRP) configuration event, and The method further comprises: When a MR associated with a multiple TRP configuration event is received from the UE, sending configuration information of multiple TRPs to the UE; and sending a fast link adaptation request message to at least one second BS, the fast link adaptation request message including information of a UE in which a multi-TRP configuration event occurs, and Wherein, based on the fast link adaptation request message, when a control signal requesting SRS transmission is sent from the at least one second BS to the UE, the SRS is sent from the UE to the at least one second BS.

7. A method for performing communication by a second base station (BS) in a wireless communication system, the method comprising: receiving a first message from a first BS, the first message including listening configuration information associated with a sounding reference signal (SRS) transmitted from a UE to the first BS; In response to receiving the first message, sending a response message to the first BS; as well as The SRS is received based on the listening configuration information.

8. The method according to claim 7, wherein: The listening configuration information associated with the SRS includes at least one of antenna port information and time-frequency resource information in which the SRS for which listening is requested is transmitted, and The second BS receives the SRS based on at least one of the time-frequency resource information and the antenna port information.

9. The method according to claim 7, wherein: The configuration information of at least one MR includes configuration information related to criteria for triggering an event related to handover, The receiving the first message including the interception configuration information includes: when the first BS receives the MR associated with the event related to the handover, receiving the handover request message including the interception configuration information.

10. The method according to claim 7, wherein: The configuration information of the at least one MR includes at least one of configuration information related to a criterion for triggering an event related to interception and configuration information related to a criterion for triggering an event related to switching, The receiving the first message including the interception configuration information includes: when the first BS receives at least one of an MR associated with an event related to interception and an MR associated with an event related to switching, receiving the first message including the interception configuration information.

11. The method according to claim 7, further comprising: receiving a handover request message for the UE from the first BS; as well as A response message to the handover request message is sent to the first BS.

12. The method according to claim 7, wherein: The response message sent includes: When it is impossible to receive the SRS based on the listening configuration information, information on at least one SRS resource to be received by the second BS and a negative acknowledgement (NACK) for the listening configuration information are transmitted to the first BS.

13. The method according to claim 7, wherein: The configuration information of at least one MR includes configuration information related to criteria for triggering a multi-TRP configuration event; and The method further comprises: receiving a fast link adaptation request message including information of the UE based on the MR associated with the multi-TRP configuration event received by the first BS from the UE; Sending a control signal requesting SRS transmission to the UE based on the fast link adaptation request message; and The SRS is received from the UE based on the control signal.

14. A method for performing communication by a user equipment (UE) in a wireless communication system, the method comprising: receiving configuration information of at least one measurement report (MR) from a first BS serving as a serving base station (BS); as well as When an event is detected based on the configuration information of at least one MR, a MR associated with the event is sent to the first BS, wherein a first message including the listening configuration information is received by at least one second BS from the first BS based on the received MR, and The at least one second BS receives a sounding reference signal (SRS) transmitted from the UE to the first BS based on the listening configuration information.

15. The method according to claim 14, wherein: The listening configuration information includes at least one of antenna port information and time-frequency resource information in which the SRS for which listening is requested is transmitted, and The at least one second BS that has received the first message including the listening configuration information receives the SRS based on at least one of the time-frequency resource information and the antenna port information.

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