Apparatus and method for selecting a cell in a wireless communication system

Abstract

Provided are an apparatus of a terminal UE and a base station in a wireless communication system and a method executed by the apparatus. The UE includes: at least one transceiver; and at least one processor, operably coupled to the at least one transceiver, the at least one processor being configured to: control the at least one transceiver to receive a measurement configuration for one or more cells from the base station; control the at least one transceiver to receive one or more downlink signals associated with one or more beams on the cell; obtain a measurement result of the cell based on the measurement configuration; and control the at least one transceiver to send the measurement result of the cell to the base station, wherein the measurement result includes a result of layer 3 filtering for the cell quality of the cell, wherein the cell quality is obtained based on an average of signal qualities of downlink signals in the one or more downlink signals, and wherein each of the signal qualities is higher than a threshold.

Description

[0001] This application is a divisional application of an invention patent application with an international application date of September 6, 2017, application number 201780055232.9, and title “Device and method for selecting a cell in a wireless communication system”. Technical Field

[0002] The present disclosure relates to a wireless communication system, and more particularly to an apparatus and method for selecting a cell in a wireless communication system. Background Art

[0003] In order to meet the increased demand for wireless data services since the deployment of the 4th generation (4G) communication system, efforts have been made to develop improved 5th generation (5G) or pre-5G communication systems. Therefore, 5G or pre-5G communication systems are also called "beyond 4G networks" or "post-LTE systems."

[0004] 5G communication systems are considered to be implemented in higher frequency (mmWave) bands (e.g., 60 GHz bands) in order to achieve higher data rates. In order to reduce the propagation loss of radio waves and increase the transmission distance, beamforming, massive multiple-input multiple-output (MIMO), full-dimensional MIMO (FD-MIMO), array antennas, analog beamforming, and massive antenna technologies are discussed in 5G communication systems.

[0005] In addition, in the 5G communication system, development of system network improvements is underway based on advanced small cells, cloud radio access network (RAN), ultra-dense networks, device-to-device (D2D) communication, wireless backhaul, mobile networks, cooperative communications, coordinated multi-point (CoMP), receiving-end interference cancellation, etc.

[0006] In 5G systems, hybrid FSK and QAM modulation (FQAM) and sliding window superposition coding (SWSC) have been developed as advanced coded modulation (ACM), and filter bank multi-carrier (FBMC), non-orthogonal multiple access (NOMA) and sparse code multiple access (SCMA) as advanced access technologies.

[0007] In a mobile communication system, it is necessary to support the mobility of the terminal. The fifth generation (5G) system also supports the mobility of the terminal. To this end, the terminal can continuously measure the quality of the serving cell currently providing service and the quality of the neighboring cells and report them to the network. In order to determine the quality of the cell, it is necessary to consider the strength of the signal received from the corresponding cell. However, in a wireless communication system based on beamforming, when a cell is selected based only on the strength of the received signal, it may not actually be possible to select a cell that can serve its purpose. Therefore, it is necessary to select a reference for the cell by a new method.

[0008] The above information is presented as background information only to assist with an understanding of the present disclosure. No determination has been made, and no assertion is made, as to whether any of the above may be applicable as prior art with respect to the present disclosure. Summary of the invention

[0009] Solution to the problem

[0010] Aspects of the present disclosure are to address at least the above problems and / or disadvantages and to provide at least the advantages described below. Therefore, one aspect of the present disclosure is to provide an apparatus and method for effectively selecting a cell in a wireless communication system.

[0011] Another aspect of the present disclosure provides an apparatus and method for defining a cell in a wireless communication system.

[0012] Another aspect of the present disclosure provides an apparatus and method for determining an optimal received signal strength of a cell in a wireless communication system.

[0013] Another aspect of the present disclosure provides an apparatus and method for determining path diversity (PD) of a cell in a wireless communication system.

[0014] Another aspect of the present disclosure provides an apparatus and method for discovering a best cell in a wireless communication system.

[0015] Another aspect of the present disclosure provides an apparatus and method for determining an operation mode of a terminal, for determining a best cell in a wireless communication system.

[0016] Another aspect of the present disclosure provides an apparatus and method for reporting measurement through beamforming in a wireless communication system.

[0017] Another aspect of the present disclosure provides an apparatus and method for selecting a primary cell or a secondary cell in a wireless communication system.

[0018] Another aspect of the present disclosure provides an apparatus and method for selecting a master cell group (MCG) or a secondary cell group (SCG) in a wireless communication system.

[0019] According to one aspect of the present disclosure, a device of a terminal in a wireless communication system is provided. The device includes: at least one transceiver; and at least one processor operably coupled to the at least one transceiver. The at least one processor is configured to control the at least one transceiver to communicate through a cell determined based on information about the strength of a received signal of a first cell and a PD of the first cell. The PD includes information about a path associated with the first cell.

[0020] According to another aspect of the present disclosure, a device of a base station in a wireless communication system is provided. The device includes: at least one transceiver; and at least one processor operably coupled to the at least one transceiver. The at least one processor is configured to receive a measurement result of a first cell from a terminal and identify a cell to perform communication with the terminal. The measurement result includes information about the strength of a received signal of the first cell and a PD of the first cell. The PD includes information about a path associated with the first cell.

[0021] According to another aspect of the present disclosure, a method for operating a terminal in a wireless communication system is provided. The method includes: communicating through a cell determined based on information about the strength of a received signal of a first cell and a PD of the first cell. The PD includes information about a path associated with the first cell.

[0022] According to another aspect of the present disclosure, a method for operating a BS in a wireless communication system is provided. The method includes: receiving a measurement result of a first cell from a terminal, and identifying a cell to perform communication with the terminal. The measurement result includes information about the strength of a received signal of the first cell and a PD of the first cell. The PD includes information about a path associated with the first cell.

[0023] According to another aspect of the present disclosure, a method performed by a user equipment UE in a wireless communication system is provided, the method comprising: receiving a measurement configuration for one or more cells from a base station; receiving one or more downlink signals associated with one or more beams on the cell; obtaining a measurement result of the cell based on the measurement configuration; and sending the measurement result of the cell to the base station, wherein the measurement result includes a result of layer 3 filtering for the cell quality of the cell, wherein the cell quality is obtained based on an average of signal qualities of downlink signals in the one or more downlink signals, and wherein each of the signal qualities is higher than a threshold.

[0024] According to another aspect of the present disclosure, a method performed by a base station in a wireless communication system is provided, the method comprising: sending a measurement configuration for one or more cells to a user equipment UE; and receiving a measurement result of the cell based on the measurement configuration from the UE, wherein the measurement result comprises a result of layer 3 filtering for the cell quality of the cell, wherein the cell quality corresponds to an average of signal qualities of downlink signals in one or more downlink signals associated with one or more beams on the cell, and wherein each of the signal qualities is above a threshold.

[0025] According to another aspect of the present disclosure, a user equipment (UE) in a wireless communication system is provided, the UE comprising: at least one transceiver; and at least one processor operably coupled to the at least one transceiver, the at least one processor being configured to: control the at least one transceiver to receive a measurement configuration for one or more cells from a base station; control the at least one transceiver to receive one or more downlink signals associated with one or more beams on a cell; obtain a measurement result of the cell based on the measurement configuration; and control the at least one transceiver to send the measurement result of the cell to the base station, wherein the measurement result includes a result of layer 3 filtering of the cell quality of the cell, wherein the cell quality is obtained based on an average of signal qualities of downlink signals in the one or more downlink signals, and wherein each of the signal qualities is higher than a threshold.

[0026] According to another aspect of the present disclosure, an apparatus of a base station in a wireless communication system is provided, comprising: at least one transceiver; and at least one processor, operably coupled to the at least one transceiver, the at least one processor being configured to: control the at least one transceiver to send a measurement configuration for one or more cells to a user equipment UE; and control the at least one transceiver to receive a measurement result of the cell based on the measurement configuration from the UE, wherein the measurement result includes a result of layer 3 filtering of the cell quality of the cell, wherein the cell quality corresponds to an average of the signal qualities of a downlink signal in one or more downlink signals associated with one or more beams on the cell, and wherein each of the signal qualities is higher than a threshold.

[0027] The apparatus and method according to various embodiments of the present disclosure may select a cell for an intended purpose by considering a beam-defined cell.

[0028] Other aspects, advantages, and salient features of the disclosure will become apparent to those skilled in the art from the following detailed description, which, taken in conjunction with the annexed drawings, discloses various embodiments of the disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] 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:

[0030] Figure 1 A wireless communication system according to various embodiments of the present disclosure is shown;

[0031] Figure 2 is a block diagram illustrating a BS in a wireless communication system according to an embodiment of the present disclosure;

[0032] Figure 3 The configuration of a terminal in a wireless communication system according to an embodiment of the present disclosure is shown;

[0033] Figure 4A , 4B 4C show the configuration of a communication unit in a wireless communication system according to various embodiments of the present disclosure;

[0034] Figure 5A The concept of a cell according to an embodiment of the present disclosure is shown;

[0035] Figure 5B An example of a wireless communication environment according to an embodiment of the present disclosure is shown;

[0036] Figure 5C Another example of a wireless communication environment according to an embodiment of the present disclosure is shown;

[0037] Figure 6 An example of a wireless communication environment for determining an optimal received signal value according to an embodiment of the present disclosure is shown;

[0038] Fig. 7A An example of determining an optimal received signal value according to an embodiment of the present disclosure is shown;

[0039] Figure 7B Another example of determining the best received signal value according to an embodiment of the present disclosure is shown;

[0040] Figure 8 An example of a wireless communication environment for determining a path diversity (PD) value according to an embodiment of the present disclosure is shown;

[0041] Fig. 9 An example of determining PD according to an embodiment of the present disclosure is shown;

[0042] Fig.10 shows an example of comparison of PD values ​​according to an embodiment of the present disclosure;

[0043] Fig.11A is a flowchart illustrating an operation of a terminal for determining a cell representative value (CRV) according to an embodiment of the present disclosure;

[0044] Fig. 11B is a flowchart illustrating the operation of a terminal for cell selection according to an embodiment of the present disclosure;

[0045] Fig. 12A An example of a measurement report according to an embodiment of the present disclosure is shown;

[0046] Fig. 12B An example of an access process according to an embodiment of the present disclosure is shown;

[0047] Fig.13 An example of cell selection of a terminal supporting carrier aggregation (CA) according to an embodiment of the present disclosure is shown;

[0048] Fig.14 is a flowchart illustrating an operation of cell selection of a terminal supporting CA according to an embodiment of the present disclosure;

[0049] Fig.15 An example of a cell group and cell selection of a terminal supporting dual connectivity (DC) according to an embodiment of the present disclosure is shown;

[0050] Fig.16 is a flowchart illustrating an operation for selecting a cell group and a cell of a terminal supporting DC according to an embodiment of the present disclosure;

[0051] Fig.17 An example of selecting a radio access technology (RAT) supporting a master cell group (MCG) according to an embodiment of the present disclosure is shown;

[0052] Fig.18 is a flowchart illustrating an operation of a terminal for selecting a RAT supporting MCG according to an embodiment of the present disclosure;

[0053] Fig.19 An example of application-based cell selection according to an embodiment of the present disclosure is shown;

[0054] Fig. 20 is a flowchart illustrating the operation of a terminal for cell selection based on an application according to an embodiment of the present disclosure;

[0055] Fig.21 An example of cell selection based on terminal movement according to an embodiment of the present disclosure is shown;

[0056] Fig. 22 is a flowchart illustrating an operation of a terminal for cell selection based on movement of the terminal according to an embodiment of the present disclosure; and

[0057] Fig.23 An example of operation of an unmanned aerial vehicle (UAV) according to an embodiment of the present disclosure is shown.

[0058] Throughout the drawings, like reference numerals will be understood to refer to like parts, components and structures. DETAILED DESCRIPTION

[0059] The following description with reference to the accompanying drawings is provided to assist in a comprehensive understanding of the various embodiments of the present disclosure as defined by the claims and their equivalents. It includes various specific details to assist in understanding, but these are to be regarded as exemplary only. Therefore, it will be appreciated by those of ordinary skill in the art that various changes and modifications may be made to the various embodiments described herein without departing from the scope and spirit of the present disclosure. In addition, descriptions of well-known functions and structures may be omitted for clarity and conciseness.

[0060] The terms and words used in the following description and claims are not limited to the bibliographical meanings, but are merely used by the inventor to enable a clear and consistent understanding of the present disclosure. Therefore, it will be apparent to those skilled in the art that the following description of various embodiments of the present disclosure is provided for illustrative purposes only and not for the purpose of limiting the present disclosure as defined by the appended claims and their equivalents.

[0061] It should be understood that the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to "a component surface" includes reference to one or more of such surfaces.

[0062] The terms used in the present disclosure are only used to describe specific embodiments and are not intended to limit the present disclosure. Unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as the meaning generally understood by those skilled in the art to which the present disclosure belongs. Terms such as those defined in commonly used dictionaries can be interpreted as having the meaning equal to the contextual meaning in the relevant field, and unless clearly defined in the present disclosure, should not be interpreted as having an ideal or overly formal meaning. In some cases, even the terms defined in the present disclosure should not be interpreted as excluding embodiments of the present disclosure.

[0063] Hereinafter, various embodiments of the present disclosure will be described based on a hardware method. However, various embodiments of the present disclosure include techniques using both hardware and software, and therefore, various embodiments of the present disclosure may not exclude the perspective of software.

[0064] The expressions "first", "second", "the first" or "the second" used in various embodiments of the present disclosure may modify various components, regardless of order and / or importance, but do not limit the corresponding components. When an element (e.g., a first element) is referred to as being "(functionally or communicatively) connected", or "directly coupled" to another element (a second element), the element may be directly connected to the other element or connected to the other element through another element (e.g., a third element).

[0065] Depending on the circumstances, the expression "configured to" as used in various embodiments of the present disclosure may be used interchangeably with, for example, "suitable for," "capable of," "designed to," "adapted to," "so that," or "capable of" in terms of hardware or software. Alternatively, in some cases, the expression "the device is configured to" may mean that the device, together with other devices or components, is "capable of." For example, the phrase "the processor is adapted (or configured) to perform A, B, and C" may mean a dedicated processor (e.g., an embedded processor) that is only used to perform the corresponding operations, or a general-purpose processor (e.g., a central processing unit (CPU) or an application processor (AP)) that can perform the corresponding operations by running one or more software programs stored in a memory device.

[0066] The present disclosure relates to an apparatus and method for selecting a cell in a wireless communication system. More specifically, the present disclosure describes a technique for selecting a cell by a process of determining path diversity (PD) in a wireless communication system.

[0067] The terms related to signals, channels, measurements, control information, network entities, and elements of devices are used only for convenience of description. Therefore, the present disclosure is not limited to the terms described below, and other terms with equivalent technical meanings may be used.

[0068] For ease of description, terms related to control information used in the following description, terms for calculating states (e.g., modes and operations), terms related to data (e.g., information or values), terms related to network entities (e.g., cells or 5GNBs), terms related to messages (e.g., reports or signals), and terms related to elements of devices are adopted. Therefore, the present disclosure is not limited to the terms described below, and other terms with equivalent technical meanings may be used.

[0069] Although the present disclosure describes various embodiments based on terms used in some communication standards (e.g., Long Term Evolution (LTE) and Advanced LTE (LTE-A) systems), they are only examples for description. Various embodiments of the present disclosure can be easily modified and applied to other communication systems.

[0070] Figure 1 A wireless communication system according to an embodiment of the present disclosure is shown.

[0071] refer to Figure 1 , a base station (BS) 110, a terminal 120, and a terminal 130 are shown as some nodes using a wireless channel in a wireless communication system. Figure 1 Only one BS is shown, but another BS that is the same as or similar to the BS 110 may be further included.

[0072] BS 110 is a network infrastructure element that provides wireless access to terminals 120 and 130. BS 110 has a coverage range defined for a predetermined geographical area based on the distance at which a signal can be transmitted. BS 110 may be referred to as an "access point (AP)", "eNodeB (eNB)", "5th generation (5G) node", "5G NodeB (NB)", "radio point", "transmission / reception point (TRP)", or other terms having equivalent technical meanings as well as "BS".

[0073] Each of the terminals 120 and 130 is a device used by a user and performs communication with the BS 110 through a wireless channel. Depending on the situation, at least one of the terminals 120 and 130 may operate without user participation. At least one of the terminals 120 and 130 may be a device that performs machine type communication (MTC) and may not be carried by a user. Each of the terminals 120 and 130 may be referred to as a "user equipment (UE)", "mobile station", "subscriber station", "remote terminal", "wireless terminal", "user equipment", or other terms having equivalent technical meanings as well as "terminal".

[0074] BS110, terminal 120 and terminal 130 can send and receive wireless signals in millimeter wave (mmWave) frequency bands (e.g., 28 GHz, 30 GHz, 38 GHz and 60 GHz). In order to increase channel gain, BS110, terminal 120 and terminal 130 can perform beamforming. Beamforming may include transmit beamforming and receive beamforming. That is, BS110, terminal 120 and terminal 130 can assign directivity to transmit signals and receive signals. To this end, BS110 and terminals 120 and 130 can select service beams 112, 113, 121 and 131 through a beam search process.

[0075] Figure 2 A configuration of a BS in a wireless communication system according to various embodiments of the present disclosure is shown. Figure 2 The configuration shown in can be understood as the configuration of BS110. The term "unit" or the term "unit" used hereinafter can refer to a unit for processing at least one function or operation, and can be implemented in hardware, software, or a combination of hardware and software. Various units can be implemented as at least one processor that is programmed or configured to perform the described operations.

[0076] refer to Figure 2 , the BS 110 may include a wireless communication unit 210 , a backhaul communication unit 220 , a storage unit 230 , and a controller 240 .

[0077] The wireless communication unit 210 performs functions for sending and receiving signals through a wireless channel. For example, the wireless communication unit 210 can perform the function of converting between a baseband signal and a bit stream according to the physical layer standard of the system. In data transmission, the wireless communication unit 210 generates a composite symbol by encoding and modulating the transmission bit stream. In data reception, the wireless communication unit 210 reconstructs the received bit stream by demodulating and decoding the baseband signal. The wireless communication unit 210 up-converts the baseband signal into a radio frequency (RF) band signal, transmits the converted signal through an antenna, and then down-converts the RF band signal received through the antenna into a baseband signal.

[0078] To this end, the wireless communication unit 210 may include a transmission filter, a reception filter, an amplifier, a mixer, an oscillator, a digital-to-analog converter (DAC), an analog-to-digital converter (ADC), etc. The wireless communication unit 210 may include multiple transmission / reception paths. The wireless communication unit 210 may include at least one antenna array consisting of multiple antenna elements. On the hardware side, the wireless communication unit 210 may include a digital unit and an analog unit, and the analog unit may include multiple subunits according to operating power, operating frequency, etc.

[0079] The wireless communication unit 210 transmits and receives signals as described above. Therefore, the wireless communication unit 210 may be referred to as a "transmitter," "receiver," or "transceiver." In addition, in the following description, transmission and reception performed through a wireless channel may be used to have a meaning including the processing performed by the wireless communication unit 210 as described above.

[0080] According to various embodiments of the present disclosure, the wireless communication unit 210 may transmit a reference signal. The reference signal may be a signal for determining the best received signal value of each of at least one cell of the BS 110. The wireless communication unit 210 may receive a measurement result corresponding to the reference signal. The measurement result may include a measurement result for the cell of the BS 110. The measurement result may include a cell representative value (CRV) of the BS 110.

[0081] The backhaul communication unit 220 provides an interface for performing communication with other nodes within the network. The backhaul communication unit 220 converts a bit stream sent from the BS 110 to another node (e.g., another access node, another BS, a higher node, or a core network) into a physical signal, and converts a physical signal received from another node into a bit stream.

[0082] The storage unit 230 stores basic programs, applications, and data such as setting information for the operation of the BS 110. The storage unit 230 may include a volatile memory, a nonvolatile memory, or a combination of a volatile memory and a nonvolatile memory. The storage unit 230 provides stored data in response to a request from the controller 240.

[0083] The controller 240 controls general operations of the BS 110. For example, the controller 240 transmits and receives signals through the wireless communication unit 210 or the backhaul communication unit 220. In addition, the controller 240 records data in the storage unit 230 and reads the recorded data. To this end, the controller 240 may include at least one processor.

[0084] According to various embodiments of the present disclosure, the controller 240 may include a calculation unit for performing a calculation operation on each CRV in a plurality of cells. The calculation unit may correspond to an instruction set or code stored in the storage unit 230, and may be an instruction / code at least temporarily residing in the controller 240, a storage space storing the instruction / code, or a part of a circuit included in the controller 240. Based on the setting, the calculation unit may perform an arithmetic operation for calculating a maximum value, an arithmetic operation for calculating an average value, or an arithmetic operation for calculating a sum. The controller 240 may control the BS 110 to perform operations according to various embodiments of the present disclosure described below.

[0085] Figure 3 The configuration of a terminal in a wireless communication system according to an embodiment of the present disclosure is shown. Figure 3 The configuration shown in may be understood as the configuration of the terminal 120. The term "unit" used hereinafter may refer to a unit for processing at least one function or operation and may be implemented in hardware, software, or a combination of hardware and software.

[0086] refer to Figure 3 The terminal 120 includes a communication unit 310 , a storage unit 320 and a controller 330 .

[0087] The communication unit 310 performs a function for sending / receiving a signal through a wireless channel. The communication unit 310 performs a conversion function between a baseband signal and a bit stream according to the physical layer standard of the system. When sending data, the communication unit 310 generates a composite symbol by encoding and modulating the sending bit stream. When receiving data, the communication unit 310 reconstructs the received bit stream by demodulating and decoding the baseband signal. The communication unit 310 up-converts the baseband signal to an RF band signal, transmits the converted signal through an antenna, and then down-converts the RF band signal received through the antenna to a baseband signal. The communication unit 310 may include a transmitting filter, a receiving filter, an amplifier, a mixer, an oscillator, a DAC, and an ADC.

[0088] The communication unit 310 may include multiple transmit / receive paths. In addition, the communication unit 310 may include at least one antenna array consisting of multiple antenna elements. On the hardware side, the wireless communication unit 210 may include digital circuits and analog circuits (e.g., RF integrated circuits (RFIC)). The digital circuits and analog circuits may be implemented as one package. The communication unit 310 may include multiple RF chains. The communication unit 310 may perform beamforming.

[0089] The communication unit 310 may include different communication modules to process signals in different frequency bands. The communication unit 310 may include multiple communication modules to support a variety of different radio access technologies. Different radio access technologies may include Bluetooth Low Energy (BLE), Wi-Fi, Wi-Fi Gigabyte, and cellular networks (e.g., LTE). Different frequency bands may include ultra-high frequency (SHF) (e.g., 2.5 GHz or 5 GHz) bands and millimeter (mm) wave (e.g., 60 GHz) bands.

[0090] The communication unit 310 transmits and receives signals as described above. Therefore, the communication unit 310 may be referred to as a "transmitter," "receiver," or "transceiver." In the following description, transmission and reception performed through a wireless channel are used to have a meaning including the processing performed by the communication unit 310 as described above.

[0091] According to an embodiment of the present disclosure, the communication unit 310 may receive a reference signal. The reference signal may be a reference signal received through different beam pairs or different paths. The communication unit 310 may determine the best received signal value for each of the at least one cell. The communication unit 310 may send a measurement result corresponding to the reference signal. The measurement result may include a measurement result for a specific cell. The measurement result may include a CRV for a specific cell.

[0092] The storage unit 320 stores basic programs, applications, and data, such as setting information for the operation of the terminal 120. The storage unit 320 may include a volatile memory, a nonvolatile memory, or a combination of a volatile memory and a nonvolatile memory. The storage unit 320 provides stored data in response to a request from the controller 330.

[0093] The controller 330 controls the general operation of the terminal 120. For example, the controller 330 sends and receives signals through the communication unit 310. The controller 330 records data in the storage unit 320 and reads the recorded data. To this end, the controller 330 may include at least one processor or microprocessor, or may be a part of a processor. The communication unit 310 or the relevant part of the controller 330 may be referred to as a communication processor (CP). The controller 330 may include a measurement calculation unit for calculating the CRV by the terminal 120. The measurement calculation unit may perform an arithmetic operation for determining a reference signal received power (RSRP) value representing multiple RSRP values. The measurement calculation unit may perform an arithmetic operation for calculating a maximum value, an arithmetic operation for calculating an average value, or an arithmetic operation for calculating a sum. The measurement calculation unit may calculate the CRV representing a specific cell by applying a preset weighting value to each of the determined RSRP value and PD value. The controller 330 may control the terminal 120 to perform operations according to various embodiments described below.

[0094] Figure 4A , 4B 4C show the configuration of a communication unit in a wireless communication system according to an embodiment of the present disclosure. Figure 4A , 4B and 4C shows Figure 2 The communication unit 210 or Figure 3 More specifically, Figure 4A , 4B and 4C show the elements for performing beamforming, as Figure 2 The communication unit 210 or Figure 3 Part of the communication unit 310.

[0095] refer to Figure 4A , the communication unit 210 or 310 includes a coding and modulation unit 402 , a digital beamforming unit 404 , a plurality of transmission paths 406 - 1 to 406 -N, and an analog beamforming unit 408 .

[0096] The coding and modulation unit 402 performs channel coding. For channel coding, at least one of a low density parity check (LDPC) code, a convolutional code, and a polar code may be used. The coding and modulation unit 402 generates modulation symbols by performing constellation mapping.

[0097] The digital beamforming unit 404 performs beamforming on a digital signal (e.g., a modulation symbol). To this end, the digital beamforming unit 404 multiplies the modulation symbol with a beamforming weight value. The beamforming weight value can be used to change the size and phase of the signal and can be referred to as a "precoding matrix" or a "precoder". The digital beamforming unit 404 outputs the digital beamformed modulation symbol to a plurality of transmission paths 406-1 to 406-N. According to a multiple-input multiple-output (MIMO) transmission scheme, the modulation symbol can be multiplexed, or the same modulation symbol can be provided to a plurality of transmission paths 406-1 to 406-N.

[0098] A plurality of transmission paths 406-1 to 406-N converts the digital signal of digital beamforming into an analog signal. To this end, each of the plurality of transmission paths 406-1 to 406-N may include an inverse fast Fourier transform (IFFT) calculation unit, a cyclic prefix (CP) insertion unit, a DAC, and an up-conversion unit. The CP insertion unit is used for an orthogonal frequency division multiplexing (OFDM) scheme, and the CP insertion unit may be omitted when another physical layer scheme (e.g., filter bank multi-carrier (FBMC)) is applied. A plurality of transmission paths 406-1 to 406-N provide independent signal processing processes for a plurality of streams generated by digital beamforming. However, depending on the implementation, some elements in the plurality of transmission paths 406-1 to 406-N may be used in common.

[0099] The analog beamforming unit 408 performs beamforming on the analog signal. To this end, the digital beamforming unit 404 multiplies the analog signal by the beamforming weight value. The beamforming weight value is used to change the magnitude and phase of the signal. According to the connection structure between the multiple transmission paths 406-1 to 406-N and the antenna, the analog beamforming unit 408 can Figure 4B Or the configuration shown in 4C.

[0100] refer to Figure 4B , the signal input to the analog beamforming unit 408 can be sent through the antenna via phase / magnitude conversion and amplification operations. At this time, the signals in each path are sent through different antenna groups, i.e., antenna arrays. In the processing of the signal input through the first path, the signal is converted by the phase / magnitude conversion units 412-1-1 to 412-1-M into a signal sequence with the same or different phases / magnitudes, amplified by the amplifiers 414-1-1 to 414-1-M, and sent through the antenna.

[0101] refer to Figure 4C, the signal input to the analog beamforming unit 408 is sent through the antenna via phase / magnitude conversion and amplification operations. The signals in each path are sent through the same antenna group (i.e., antenna array). In the processing of the signal input through the first path, the signal is converted into a signal sequence with the same or different phases / magnitudes by the phase / magnitude conversion units 412-1-1 to 412-1-M, and amplified by the amplifiers 414-1-1 to 414-1-M. In order to be sent through an antenna array, the amplified signal is summed by the summing units 416-1-1 to 416-1-M and then sent through the antenna.

[0102] Figure 4B An example of using a separate antenna array for each transmission path is shown, and Figure 4C An example in which transmission paths share one antenna array is shown. However, according to another embodiment of the present disclosure, some transmission paths may use independent antenna arrays, and the remaining transmission paths may share one antenna array. According to another embodiment of the present disclosure, a structure that can be adaptively changed depending on the situation can be used by applying a switchable structure between the transmission path and the antenna array.

[0103] A cell may refer to an area that one BS may cover. One BS may cover a single cell or multiple cells. Multiple cells may be divided by the frequency supporting multiple cells or the area covering a sector. Hereinafter, the term "BS" may be used as a term including a cell, or the term "cell" may be used as a term referring to a BS.

[0104] A serving cell may correspond to a cell that provides higher layer signaling (e.g., radio resource control (RRC) signaling) to a terminal, and may refer to a single cell or multiple cells. When the terminal is not configured to support carrier aggregation (CA) or dual connectivity (DC), the serving cell may be a single cell including a primary cell. When the terminal is configured to support CA or DC, the serving cell may be a set of one or more cells including a primary cell and at least one second cell.

[0105] Figure 5A Elements for indicating a cell according to an embodiment of the present disclosure are shown.

[0106] refer to Figure 5A , the element may be a received signal 501 or a PD 502 .

[0107] The received signal 501 may indicate information about a signal associated with a cell. A signal associated with a cell may refer to a signal received by a cell. The information about a signal may include a parameter associated with the signal. For example, a parameter associated with a signal may be an index indicating signal strength or an index indicating signal quality. A parameter associated with a signal may be a parameter selected from parameters of a plurality of signals including the signal. For example, a parameter associated with a signal may refer to a highest signal strength value among signal strength values ​​of a plurality of signals.

[0108] In the following, the best received signal value may refer to the highest value among multiple received signal values. Multiple received signal values ​​may refer to received signal values ​​measured from multiple signals (e.g., reference signals) transmitted and received by all beam pairs that can be configured by the BS (or cell) and the terminal. The best received signal value may refer to the maximum value among the received signal values ​​measured for all beam pairs between the BS and the terminal. The received signal value may be represented by signal strength, such as RSRP, reference signal received quality (RSRQ), and received signal strength indicator (RSSI). Alternatively, the received signal value may be represented as signal quality, such as signal to interference and noise ratio (SINR), carrier to interference and noise ratio (CINR), and signal to noise ratio (SNR).

[0109] PD 502 may be information about a path. A path may be a path through which a signal may be transmitted. A path may be a path associated with an electronic device. Information about a path associated with an electronic device may include information about the number of paths supported by the electronic device. A path may be a path associated with a cell. Information about a path associated with a cell may include information about the number of paths. For example, a cell with three paths is guaranteed to have a slightly better PD than a cell with one path. Each path may be a path through which a signal may be transmitted by a cell. A path may be a path included in a channel between a terminal and a BS.

[0110] In the following, PD may be information about a path between a BS (or cell) and a terminal. PD may be evaluated based on a path that guarantees at least a predetermined quality level or at least a predetermined reception intensity level. Since PD is guaranteed, the terminal can communicate with the BS through various channel environments. At the same time, PD may include information about the degree of independence of the path. That is, PD may indicate the degree of correlation (or uncorrelation) of the path. PD may be represented by a value within a predetermined range. In this case, as the diversity value is higher, it may mean that the number of independent paths is larger. As the diversity value is lower, it may mean that the number of correlated paths is larger. As the diversity value is higher, it may mean that the directions of the two beam pairs are more different. As the diversity value is lower, it may mean that the directions of the two beam pairs are more similar.

[0111] Hereinafter, a path may refer to a channel for transmitting a wireless signal. The path may correspond to a beam pair. The path may correspond to a beam pair. In some cases, the path may be referred to as a "link," "channel," or another term having an equivalent meaning.

[0112] In the present disclosure, the characteristics of a cell may be expressed taking into account the received signal 501 and the PD 502. The characteristics of a cell may include at least one of the data throughput when sending / receiving a signal through the cell, the security level when performing communication through the cell, the degree of robustness to noise or interference, obstacles when performing communication through the cell, and the degree of influence from elements such as mobile objects. The characteristics of a cell may include information about how suitable the cell is for communication or how well the cell serves the purpose of the terminal (or user). Based on the characteristics of each of the multiple cells, at least one cell 503 may be selected. The device according to various embodiments of the present disclosure may select a cell taking into account a path (e.g., PD 502) as well as a received signal 501. Depending on a predetermined process, the device may be a terminal or a network entity other than a BS.

[0113] Hereinafter, the present disclosure describes a method and embodiments thereof for acquiring information indicating characteristics of a corresponding cell (eg, information representing a cell) in consideration of a best received signal value of the cell and a PD of the cell.

[0114] Figure 5B An example of a wireless communication environment according to various embodiments of the present disclosure is shown.

[0115] refer to Figure 5B , the wireless communication environment may be the wireless communication environment 500a or the wireless communication environment 500b.

[0116] refer to Figure 5B , the wireless communication environment 500a and the wireless communication environment 500b may include a BS 510, a BS 520, and a terminal 530. The BS 510 may provide a service to the terminal 530 located in the cell 511. The BS 520 may provide a service to the terminal 530 located in the cell 521. The cell 511 may provide a path 555, a path 556, and a path 557 to the terminal 530 located in the position 533. The cell 521 may provide a path 551 to the terminal 530 located in the position 533.

[0117] The wireless communication environment 500a may illustrate a situation where the terminal 530 moves from position 531 to position 533 before the obstacle 560 enters. Position 533 may be included in an area where the signals of the cell 511 and the cell 521 are all received by the terminal 530. After moving to position 533, the terminal 530 may perform a measurement report on a neighboring cell for switching from a serving cell to a target cell, or perform a cell search and measurement for initial access or re-access. The terminal 530 may measure signals received from multiple cells (e.g., cell 511 and cell 521) and determine a received signal value. Figure 5B , it is assumed that the received signal value increases in the order of the signal received through path 551, the signal received through path 556, the signal received through path 557, and the signal received through path 555. Obstacle 540 blocks path 555. Terminal 530 may determine that the received signal value of cell 521 providing path 551 is the largest. Therefore, terminal 530 may determine that cell 521 is most suitable for the configuration of connection. Terminal 530 may connect to cell 521 through an access procedure (e.g., a random access procedure or an RRC connection procedure).

[0118] Wireless communication environment 500b represents a situation where terminal 530 moves from position 531 to position 533 and then obstacle 560 enters. When obstacle 560 enters, cell 521 may not be able to provide the best communication service to terminal 530 through path 551. For example, due to the entry of obstacle 560, terminal 530 may detect that the measured received signal value is less than a specific threshold and determine that a radio link failure (RLF) has occurred. Terminal 530 may attempt to restore the radio link after determining the occurrence of RLF. Due to the occurrence of RLF, the quality of service received by terminal 530 may deteriorate. Due to the delay time attributable to the detection of the occurrence of RLF (about 1000ms) and the delay time attributable to the recovery of RLF (about 1000ms), the service to terminal 530 may be delayed.

[0119] When the radio link is not restored, the terminal 530 may establish a new RRC connection. The terminal 530 may select the cell 511 that provides the link of the path 556. When the obstacle 560 escapes from the path 551, the terminal 530 may determine that the received signal value measured later through the path 551 is greater than the received signal value from other paths. The terminal 530 may select the cell 521 that provides the link of the path 551 again. When the terminal 530 repeatedly changes the cell selected according to the movement of the obstacle 560, a ping-pong phenomenon may occur.

[0120] exist Figure 5BIn the wireless communication environment shown in , when cell 511 provides three paths, cell 521 provides one path. When terminal 530 selects cell 521 in consideration of only the received signal value, the above problem may occur in the case where path 551 is blocked. However, when terminal 530 selects cell 511 in consideration of the number of paths, even if path 555, which is one of the three paths, is blocked by obstacle 540, other paths 556 and 557 are still available, so terminal 530 may not experience RLF or ping-pong phenomenon.

[0121] As described above, the method of selecting a cell based only on the best received signal value may be sensitive to the movement of obstacles. The method that only considers the best received signal value can change the state of the path even when the terminal moves, and may therefore cause degradation of communication quality, communication delay or ping-pong phenomenon. Therefore, it is preferred to select a cell taking into account the available paths and received signal values ​​between the BS (or cell) or the terminal. The available path can be a path that guarantees a predetermined quality or higher quality, or a predetermined received signal strength value or higher value. The available path may be referred to as an "available path", "valid path", "active path" or another term with equivalent technical meaning. By considering the available path, even if the cell does not provide the maximum throughput, the terminal can select a cell that serves the purpose required by the terminal or perform a measurement report for selecting a cell.

[0122] Figure 5C Another example of a wireless communication environment according to an embodiment of the present disclosure is shown.

[0123] refer to Figure 5C , the wireless communication environment may be the wireless communication environment 500c or the wireless communication environment 500d.

[0124] refer to Figure 5C , the wireless communication environment 500c and the wireless communication environment 500d may include a BS 510, a BS 520, and a terminal 570. The BS 510 may provide a service to the terminal 570 located in the cell 511. The BS 520 may provide a service to the terminal 570 located in the cell 521. The cell 511 may provide a path 555, a path 556, and a path 557 to the terminal 570 located in the position 533. The cell 521 may provide paths 551, 552, and 553 to the terminal 570 located in the position 533.

[0125] Wireless communication environment 500c shows a case where terminal 570 moves from position 531 to position 533 before obstacle 560 enters. Hereinafter, it is assumed that the received signal value increases in the order of the signal received from path 551, path 552 and path 553, the signal received from path 556, the signal received from path 557, and the signal received from path 555. Obstacle 540 has entered path 555. Figure 5B Differently, it is assumed that the terminal 570 considers the number of paths and the best received signal value when selecting a cell. The terminal 570 may provide paths 551, 552, and 553 having received signal values ​​greater than the received signal value of the cell 511, and may determine that the cell 521 is the most suitable cell for handover, or is added because the cell 521 has the same number of paths (three) as the cell 511. The terminal 570 may perform handover to the cell 521 or perform an access procedure for the cell 521.

[0126] Wireless communication environment 500d shows a situation where terminal 570 moves from position 531 to position 533 and then obstacle 560 enters. When obstacle 560 enters, cell 521 may not be able to provide the best communication service to terminal 570 through paths 551 to 553. All links of cell 521 may be blocked by one obstacle 560. This is because paths 551 to 553 are not independent paths. Terminal 570 may experience time delay or ping-pong phenomenon due to RLF detection and recovery, such as Figure 5B In contrast, among the links of cell 511, only one associated with path 555 is blocked due to obstacle 540. Cell 511 may provide services to terminal 570 through independent paths 556 and 557. When terminal 570 selects cell 511, terminal 570 may not experience the above phenomenon.

[0127] As reference Figure 5C As described, when selecting a cell, the user can avoid all available paths blocked by one obstacle by further considering the independence of the path and the number of available paths. Even if one path is blocked by an obstacle, the remaining paths can maintain their connection by selecting a cell that provides an independent path. An independent path may refer to a path with low correlation therebetween. For example, paths 551 to 553 have the same or similar directivity, and therefore have a relatively high correlation therebetween. In contrast, paths 555 to 557 have different directivities (i.e., relatively separated directivities), and therefore correspond to independent paths with relatively low correlation therebetween. The terminal can identify a path with low correlation, thereby compensating for robustness issues caused by the directional characteristics of the beam. Information about the available paths of a cell may be referred to as the "PD" of the cell. The PD of a cell may include the degree of independence of the available paths, i.e., the degree of non-correlation of the available paths of the cell. The PD value and the best received signal value may be used to select a cell that serves the desired purpose.

[0128] Hereinafter, the present disclosure describes an operation of calculating a value representing a cell taking into account the directional characteristics of a beam. Figure 6 , Fig. 7A and Figure 7BDescribes the operation of determining a received signal value taking into account multiple RSRP values. Figure 8 , Fig. 9 and Fig.10 Operations for determining a PD value for a cell in order to compensate for robustness issues are described.

[0129] Figure 6 An example of a wireless communication environment for determining an optimal received signal value according to an embodiment of the present disclosure is shown.

[0130] refer to Figure 6 , the wireless communication environment may be the wireless communication environment 600 .

[0131] refer to Figure 6 , the wireless communication environment 600 may include a BS 610, a BS 620, and a terminal 630. The BS 610 and the BS 620 may be Figure 1 The terminal 630 may be Figure 1 120 of the terminal 120. BS 610 can serve cell 611. BS 610 can communicate with terminal 630 in cell 611 through beams 641 to 647. BS 620 can serve cell 621. BS 620 can communicate with terminal 630 in cell 621 through beams 651 to 657. Terminal 630 can communicate with BS 610 or BS 620 through beams 631 to 637. The wireless communication environment 600 may include BS 680. BS 680 may be a serving BS for terminal 630. Hereinafter, although it is described that each of BS 610, BS 620 and terminal 630 performs communication through seven beams, this is only for ease of description, and the present disclosure is not limited thereto. In other words, terminal 630 can support fifteen beams.

[0132] For the cell part in the handover from the serving cell to the target cell or in the initial access process, the terminal 630 can perform measurements on the cells (e.g., cells 611 and cells 621). In the following, for ease of description, although the RSRP value of the received signal is determined by measurement, the present disclosure is not limited thereto. In addition to RSRP, RSRQ or RSSI can also be measured. When the measurement of the RSRP value of each cell is performed by the beam 631 of the terminal 630, the terminal 630 can obtain the RSRP measurement result of "-90dbm" for the cell 611 and the RSRP measurement result of "-120dbm" for the cell 621 as the neighboring cell of the cell 611. Based on the measurement results, the cell 611 can be selected. When the measurement is performed by the beam 637 of the terminal 630, the terminal 630 can obtain the RSRP measurement result of "-140dbm" for the cell 611 and the RSRP measurement value of "-60dbm" for the cell 621. Based on the measurement results, the cell 621 can be selected. That is, depending on the beam used by the terminal 630 for the measurement, different RSRP values ​​are measured and different cells are selected (for example, whether switching is performed). As described above, when a device supporting beamforming-based communication (such as BS 610, BS 620, or terminal 630) measures the received signal value of a specific cell only through (one or more) specific beams, the measurement result may not accurately represent the specific cell. Therefore, it is necessary to take into account a received signal value corresponding to cells of multiple beams. The present disclosure describes an embodiment of determining a representative received signal value based on the RSRP values ​​of multiple beams. In the following, a representative received strength value may be referred to as an "optimal received signal value", but may also be referred to as a "representative received signal value", "representative received strength" or another term with equivalent meaning.

[0133] RSRP Measurement Using Multiple Beams

[0134] When measuring a neighboring cell, the terminal 630 may need to use multiple beams in order to measure a value representing each neighboring cell. The terminal 630 can measure the neighboring cell through a beam scanning operation. One transmit beam and one receive beam can configure a path. The terminal 630 can measure each path established by the configurable beam. The terminal 630 can obtain the RSRP value of each path. For example, when four transmit beams and two receive beams are supported, the terminal 630 can obtain 8 (=4×2) RSRP values ​​in each scanning interval.

[0135] The terminal 630 may determine the best received signal value of the neighboring cell based on the RSRP value received at each scanning interval. Each of the acquired RSRP values ​​may correspond to a path (beam pair or link) determined by one transmit beam and one receive beam. The terminal 630 may derive a value corresponding to the neighboring cell based on the acquired RSRP value. The value corresponding to the neighboring cell corresponds to the best received signal value of the neighboring cell used in the cell selection, and is a value representing the neighboring cell.

[0136] The value representing the neighboring cell may be one RSRP value or a combination of two or more RSRP values ​​representing the neighboring cell, or may be determined by filtering the RSRP value at least once. In order to determine the best received signal value of the neighboring cell from the acquired RSRP value, the terminal 630 may or may not perform at least one of layer 1 filtering and layer 3 filtering. The terminal 630 may determine the best received signal value of the neighboring cell via various methods, regardless of the order of the filtering operation.

[0137] The terminal 630 may determine the best received signal value of the neighboring cell before performing layer 1 filtering, i.e., without filtering. The terminal 630 may determine the best received signal value of the neighboring cell by performing a calculation operation on all RSRP values ​​at the k-th scanning interval. For example, the terminal 630 may determine the maximum value of the RSRP value at the k-th scanning interval as the best received signal value of the neighboring cell. In another example, the terminal 630 may determine the average value of the RSRP value at the k-th scanning interval as the best received signal value of the neighboring cell. In another example, the terminal 630 may determine the sum of the RSRP values ​​at the k-th scanning interval as the best received signal value of the neighboring cell.

[0138] Terminal 630 may determine the best received signal value of the cell, such as Fig. 7A as shown in .

[0139] Fig. 7A An example of determining an optimal received signal value according to an embodiment of the present disclosure is shown.

[0140] refer to Fig. 7A , Fig. 7A FIG. 6 shows a case where BS 620 supports four beams and terminal 630 supports two beams. Eight pairs of beams are specified in each scanning interval. Therefore, terminal 630 can obtain eight RSRP values ​​R in one scanning interval. 11 , R 21 , R 31 , R 41 , R 12 , R 22 , R 32 and R 42 . Rxy Refers to the xth transmit beam (BS beam) and the yth receive beam (terminal beam).

[0141] refer to Fig. 7A , in operation 710, the terminal 630 may determine the maximum value of eight RSRP values ​​in the kth interval 701. When the maximum value is R 21 When the terminal 630 can 21 Determined as the first value 711. Hereinafter, an example of determining a representative value (eg, the first value 711 or the second value 716) of a cell at each scanning interval based on a maximum value is described, but an average value or an arithmetic sum operation may be used.

[0142] In operation 715, the terminal 630 may determine the maximum value of the eight RSRP values ​​in the k+1th interval 702. When the maximum value is R 32 When the terminal 630 can 32 Determined as the second value 716 .

[0143] In operation 720, the terminal 630 may perform layer 1 filtering on each of the first value 711 and the second value 716. The terminal 630 may obtain M from the first value 711. n-1 The terminal 630 can obtain M from the second value 716 n . M n-1 and M n It can be a cell level value.

[0144] In operation 730, the terminal 630 may perform layer 3 filtering on the result of layer 1 filtering. The terminal 630 may n-1 Get F n-1 Terminal 630 can be from M n Get F n . F n It can be a cell-level value. n-1 and F n It can be determined according to Equation 1 below.

[0145] F n =(1-a)×F n-1 +a×M n ……………………Equation 1

[0146] In Equation 1, M n Indicates the most recent measurement received from layer 1. n Indicates updated measurement results of layer 3 filtering and is used for measurement reporting. n-1 represents the previous measurement result of layer 3 filtering, and F 0 Corresponding to M 1. a represents the filtering constant.

[0147] In operation 740, the terminal 630 may evaluate whether the reporting criteria are satisfied. In addition, the terminal 630 may generate a measurement result from the layer 3 filtering result. According to various embodiments of the present disclosure, the terminal 630 may not only generate a layer 3 filtering result based on the PD value of the cell 621, but may also generate a measurement result for the cell 621. Although not shown in FIG. Fig. 7A However, when the reporting criteria are met, the terminal 630 can report the generated measurement results to the BS 680.

[0148] In other embodiments, after performing layer 3 filtering, the terminal 630 may determine the best received signal value of the neighboring cell. For example, for the RSRP value at the k-th scanning interval and the RSRP value at the k+1-th scanning interval, the terminal 630 may perform layer 1 filtering and layer 3 filtering based on the beam of the BS (beam of 5GNB) included in the neighboring cell. As a result of layer 3 filtering, the terminal 630 may calculate a value corresponding to each beam of the BS. The terminal 630 may determine the best received signal value of the neighboring cell by performing a calculation operation on the value corresponding to the beam of the BS.

[0149] In another example, for the RSRP value at the k-th scanning interval and the RSRP value at the k+1-th scanning interval, the terminal 630 may perform layer 1 filtering and layer 3 filtering based on the beam (the beam of the UE) of the terminal 630. As a result of the execution of the layer 3 filtering, the terminal 630 may calculate a value corresponding to each beam of the terminal 630. The terminal 630 may calculate the best received signal value of the neighboring cell by performing a calculation operation (e.g., a maximum value, an average value, or a sum) on the value corresponding to the beam of the terminal 630.

[0150] refer to Figure 7B A case is described in which the BS 620 supports four beams and the terminal 630 supports two beams.

[0151] Figure 7B Another example of determining the best received signal value according to an embodiment of the present disclosure is shown.

[0152] refer to Figure 7B Each scanning interval specifies eight pairs of beams. Therefore, the terminal 630 can obtain eight RSRP values ​​R in one scanning interval. 11 , R 21 , R 31 , R 41 , R 12 , R 22 , R 32 and R 42 . R xyRefers to the xth transmit beam (BS beam) and the yth receive beam (terminal beam).

[0153] refer to Figure 7B In operation 751, the terminal 630 may calculate a value 761 corresponding to the first beam of the UE 630 at the k-th scanning interval 701. The terminal 630 may calculate the value 761 corresponding to the first beam of the UE 630 at the k-th scanning interval 701 by calculating the four RSRP values ​​R 11 , R 21 , R 31 and R 41 The calculation operation is used to calculate the value 761 corresponding to the first beam of the terminal 630. Hereinafter, an example of determining the representative value of the beam of the UE at each scanning interval based on the average value is described, but a maximum value or arithmetic sum operation may be used.

[0154] In operation 752 , the terminal 630 may calculate a value 762 corresponding to the second beam of the terminal 630 at the k-th scanning interval 701 .

[0155] In operation 753 , the terminal 630 may calculate a value 763 corresponding to the first beam of the UE 630 at the k+1th scanning interval 702 .

[0156] In operation 754 , the terminal 630 may calculate a value 764 corresponding to the second beam of the terminal 630 at the k+1th scanning interval 702 .

[0157] In operation 760, the terminal 630 may perform layer 1 filtering on the values ​​761 and 763 corresponding to the first beam. The terminal 630 may obtain the M of the first beam of the terminal 630 from the values ​​761 and 763 corresponding to the first beam, respectively. n-1 and M n .

[0158] In operation 765, the terminal 630 may perform layer 1 filtering on the values ​​762 and 764 corresponding to the second beam. The terminal 630 may obtain the M of the second beam of the terminal 630 from the values ​​762 and 764 corresponding to the second beam, respectively. n-1 and M n .

[0159] In operation 770, the terminal 630 may perform layer 3 filtering on the result of layer 1 filtering. The terminal 630 may select the M of the first beam n-1 Get the F of the first beam n-1 The terminal 630 can select M of the first beam n Get the F of the first beam n F can be determined from equation 1 above n-1 and F n .

[0160] In operation 775, the terminal 630 may perform layer 3 filtering on the result of the layer 1 filtering. The terminal 630 may select the M of the second beam n Get the F of the second beam n F can be determined from equation 1 above n .

[0161] In operation 780, the terminal 630 may determine a maximum value between a result of layer 3 filtering of the first beam of the terminal 630 and a result of layer 3 filtering of the second beam as a best received signal value of the cell 621. As described above, in addition to calculating the maximum value between the result of layer 3 filtering of the first beam and the result of layer 3 filtering of the second beam, average calculation or sum calculation may also be used.

[0162] In operation 790, the terminal 630 may evaluate whether the reporting criteria are met. The terminal 630 may generate a measurement result from the determined best received signal value. According to various embodiments of the present disclosure, the terminal 630 may generate not only the best received signal value but also the measurement result of the cell 621 based on the PD value of the cell 621. Figure 7B Although not shown, when the reporting criteria are satisfied, the terminal 630 may report the generated measurement result to the BS 680 which is the serving BS.

[0163] In another example, for the RSRP value at the k-th scanning interval and the RSRP value at the k+1-th scanning interval, the terminal 630 may perform layer 1 filtering and layer 3 filtering based on each beam pair corresponding to a combination of a beam of a neighboring BS included in the neighboring cell and a beam of the terminal 630. As a result of the layer 3 filtering, the terminal 630 may calculate a value corresponding to each beam pair. The terminal 630 may determine the best received signal value of the neighboring cell by performing calculation (e.g., maximum value, average value, or sum) on the value corresponding to the beam pair.

[0164] In other embodiments, the terminal 630 may determine the best received signal value of the neighboring cell after layer 1 filtering and before layer 3 filtering.

[0165] When the best received signal value of the neighboring cell is calculated before layer 1 filtering, the terminal 630 can improve the accuracy by reflecting the instantaneous RSRP value. However, since calculations are performed on many RSRP values, a large amount of calculations may become a burden on the terminal 630. In contrast, the terminal 630 can reduce the number of calculations by calculating the best received signal value of the neighboring cell after layer 3 filtering. In some embodiments, the terminal 630 can adjust the order of calculation of the best received signal value of the neighboring cell and layer 1 filtering, and the order of the best received signal value of the neighboring cell and layer 3 filtering according to a predetermined derivation mode. The terminal 630 can adaptively control the effect of reducing the amount of calculation and improving the accuracy by changing the order of calculation and filtering operations of the best received signal value.

[0166] As described above, it is assumed that the terminal 630 measures each cell in consideration of the beam of the BS 610 or 620 and the beam of the terminal 630. The terminal 630 may obtain a measurement value "-90 dBm" as the best received signal strength value of the cell 611 through the beam 631. The terminal 630 may obtain a measurement value "-60 dBm" as the best received signal strength value of the cell 621 through the beam 637. The terminal 630 may determine to perform a handover from the cell 611 to the cell 621. In other words, the terminal 630 may determine the best received signal strength value representing the cell by considering the RSRP values ​​of all beams.

[0167] Figure 8 An example of a wireless communication environment for determining a PD value according to various embodiments of the present disclosure is shown.

[0168] refer to Figure 8 , the wireless communication environment may be the wireless communication environment 800 .

[0169] refer to Figure 8 , the wireless communication environment 800 may include Figure 6 The wireless communication environment 600 includes a BS 610, a BS 620 and a terminal 630. Figure 6 As shown in FIG. 6 , BS 610 may communicate with terminal 630 in cell 611 through beams 641 to 647. BS 620 may communicate with terminal 630 in cell 621 through beams 651 to 657. Terminal 630 may communicate with BS 610 or BS 620 through beams 631 to 637. Compared with wireless communication environment 600, wireless communication environment 800 may be an environment further including obstacle 810 and obstacle 820. Wireless communication environment 800 may include obstacle 810 between BS 610 and terminal 630. Wireless communication environment 800 may include obstacle 820 between BS 620 and terminal 630.

[0170] Terminal 630 can communicate with BS 610 through multiple beams 631 to 637. BS 610 can communicate through multiple beams 641 to 647. Based on the consideration of the downlink, one transmission beam of BS 610 and one reception beam of terminal 630 can configure a path according to the directional characteristics of the beams. For example, there can be 49 (=7×7) paths between BS 610 and terminal 630. Terminal 630 can also consider 49 paths for BS 620 and BS 610 in the same way.

[0171] The terminal 630 may measure a neighboring cell (e.g., cell 611 or cell 621) to access a stable cell. The measurement may include an operation of determining a PD value of the corresponding cell. Some paths between the terminal 630 and the cell 611 may be blocked by an obstacle 810. The terminal 630 may determine that there is an available path for the cell 611. The terminal 630 may determine a first PD value for an available path. Due to the obstacle 820, the terminal 630 may guarantee at least one available path in the path with the cell 621. The terminal 630 may determine that there are four available paths for the cell 621. The terminal 630 may determine a second PD value for the four available paths.

[0172] Between cell 611 and cell 621, cell 621 can be selected as a cell that is robust to state changes (i.e., as a stable cell). For example, when searching for a cell to be switched from a serving cell, terminal 630 can report a measurement result based on a second PD value to serving BS 680. Since the second PD value is greater than the first PD value, serving BS 680 can determine to perform a handover of terminal 630 to cell 621. In another example, when searching for a cell for initial access, terminal 630 can select cell 621 as a cell to be accessed by terminal 630. As described above, terminal 630 can consider available paths in order to select a robust cell. Terminal 630 can also indicate the robustness of a particular cell by calculating the PD value of an available path. Even in the case of the same number of available paths, when the beams included in the path have a relatively high correlation, the PD value can be relatively small. This is because the diversity of the path is not guaranteed.

[0173] PD

[0174] When measuring the cell 621, the terminal 630 may be required to consider the degree of non-correlation between available paths and the number of available paths between the paths. Hereinafter, the following description is made based on the beam of the terminal 630 as the object of performing measurement, but the process described below can be equally applied to the beam of the BS 620, which is the target of receiving the measurement report.

[0175] The terminal 630 may identify a beam corresponding to an available path among the N beams. An available path refers to a path that provides a received power greater than or equal to a threshold. The terminal 630 may determine whether the RSRP value of each beam of the terminal 630 is greater than or equal to the threshold. In some embodiments, the threshold may refer to a minimum received power for communication. In other embodiments, the threshold may refer to a minimum received power that satisfies a data rate and a modulation and coding scheme (MCS) required by an application driven by the terminal 630. In other embodiments, the threshold may be a value randomly set for a cell to be measured.

[0176] When the RSRP of the i-th beam is greater than or equal to the threshold, the terminal 630 may insert the i-th beam into the beam candidate set. When the RSRP of the j-th beam is less than the threshold, the terminal 630 may not insert the j-th beam into the beam candidate set. The terminal 630 may identify K beam candidates having RSRP values ​​greater than or equal to the threshold among the N beams. The path through the identified K beam candidates may be referred to as a valid path, a valid link, an available path, or an available link.

[0177] In order to identify available paths, an index (metric) indicating radio quality and RSRP may be used. For example, the terminal 630 may identify available paths based on RSRQ or RSSI indicating the quality of the received signal through each beam. In another example, the terminal 630 may identify available paths based on SNR, CINR, SINR, or a signal-to-interference ratio (SIR) including information related to noise and / or interference of each beam. In another example, the terminal 630 may identify available paths based on an index related to the error rate of the signal through each beam, such as error vector magnitude (EVM), bit error rate (BER), or block error rate (BLER). Although the following description will be based on RSRP, the present disclosure is not limited thereto. As described above, in order to identify available paths for determining PD values, various indexes indicating radio quality may be used.

[0178] The terminal 630 may calculate the degree of non-correlation of the available paths. The terminal 630 may calculate the degree of non-correlation of the available paths based on the beam distance (BD). More specifically, the terminal 630 may calculate the degree of non-correlation of the BD between two predetermined beams in the beams corresponding to the available paths. The BD may be defined as the distance between the coordinates indicated by the maximum gain in the main lobes of the two beams. Fig. 9 The determination of BD is performed as shown in .

[0179] Fig. 9 It is shown that the terminal 630 according to an embodiment of the present disclosure provides fifteen beams.

[0180] refer to Fig. 9, graph 900 shows a cross section with half power (3 dB) in the main lobe of fifteen beams. The fifteen beams may have indices from 0 to 14. The color corresponding to each beam indicates the intensity of the beam corresponding to axis 980. Two beams (i 1 Beam and i 2 The BD between the two beams may be the coordinate (x i1 ,y i1 , z i1 ) and (x i2 ,y i2 , z i2 ) between them. In some embodiments, the distance between two points may be the Manhattan distance. BD may be defined as the following equation 2.

[0181]

[0182] In equation 2, Indicates the i 1 Beam and i 2 BD between beams. (x i1 ,y i1 , z i1 ) indicates the i-th 1 The coordinate value in the main lobe of the beam with maximum gain. (x i2 ,y i2 , z i2 ) indicates the i-th 2 The coordinate value in the main lobe of the beam that has maximum gain.

[0183] In other embodiments, the distance between two points may be the Euclidean distance. BD may be defined as Equation 3 below.

[0184]

[0185] In equation 3, Indicates the i 1 Beam and i 2 The distance between the beams. (x i1 ,y i1 , z i1 ) indicates the i-th 1 The coordinate value in the main lobe of the beam with maximum gain. (x i2 ,y i2 , z i2 ) indicates the i-th 2 The coordinate value in the main lobe of the beam that has maximum gain.

[0186] The graph 900 may show BD 906 between the 0th beam and the 6th beam, BD 908 between the 0th beam and the 8th beam, and BD 911 between the 0th beam and the 11th beam. For example, BD 906 may be 12, BD 908 may be 33, and BD 911 may be 41. When BD 911 is longer than BD 906, the graph 900 may mean that the 11th beam and the 0th beam are not as strongly correlated as the 6th beam and the 0th beam. The BD determined from the graph 900 may indicate to what extent two beams are uncorrelated, to what extent two beams are independent of each other, or how different the directions of the two beams are.

[0187] Terminal 630 may store a table indicating the BDs of beams supported by terminal 630. In some embodiments, terminal 630 may store a table containing previously calculated BD values ​​of beams of terminal 630. The table may show predetermined pairs of two beams and the BD value between them. When the number of beams supported by terminal 630 is N, terminal 630 may store a table containing previously calculated BD values ​​of beams of terminal 630. N C 2 A table of beam pairs and BD values ​​corresponding to the beam pairs.

[0188] In other embodiments, the terminal 630 may store a table including coordinate values ​​indicating vectors on three-dimensional beams to calculate the BD value of the beam of the terminal 630. The coordinate value may be an xyz coordinate system value or a polar coordinate value. When the number of beams supported by the terminal 630 is N, the terminal 630 may store a parameter set indicating N beams.

[0189] The terminal 630 may identify a beam corresponding to an available path and determine a BD value of the identified beam from a stored table. The terminal 630 may calculate a PD value of the cell 621 based on the determined BD value. The terminal 630 may calculate a PD value of an available path. If the condition for guaranteeing the signal strength of communication between the terminal 630 and the BS 620 is not met, PD may not be guaranteed even for sufficiently unrelated paths. Therefore, the terminal 630 may calculate a PD value based on the BD values ​​of the identified K beams that are greater than or equal to a threshold. The terminal 630 may calculate a PD value according to the following equation 4.

[0190]

[0191] In Equation 4, PD represents the PD value, and BD i，j represents the BD between the i-th beam and the j-th beam. When i=j, BD i，jis 0. In the present disclosure, although it has been described that the terminal 630 can identify an available path of a plurality of paths and then determine the BD of the identified available path in order to determine the PD value of the cell, the present disclosure is not limited to the above order. The terminal 630 can determine the BD of all the plurality of beams, identify the available path, and then select the BD value only for the available path in order to determine the PD value of the cell.

[0192] When the BD between two beams is relatively long, the BD may mean that the two beams are relatively uncorrelated. This can be derived from a simulation of performing communication through a receiving beam of a terminal and a transmitting beam of a BS in the 28 GHz band. When the terminal determines two predetermined optimal transmission beams, the correlation between the two transmission beams is as shown in Table 2 below. Assume that the indexes of the beams are sequentially indexed in a clockwise direction based on the 0th beam, as Fig. 9 as shown in .

[0193] Table 1

[0194]

[0195] In case 1, the number of transmit antennas is 8, the half-power beamwidth (3dB beamwidth) is 12°, the number of transmit beams is 10, and the transmit angles are -54°, ​​12°, and 54°. In case 2, the number of transmit antennas is 12, the half-power beamwidth (3dB beamwidth) is 6°, the number of transmit beams is 20, and the transmit angles are -57°, 6°, and 57°. A line of sight (LOS) environment refers to an environment in which a straight line path between a BS and a terminal is ensured, and a non-LOS (NLOS) environment refers to an environment in which a straight line path is not ensured.

[0196] When the index difference between two beams in the LOS environment of case 1 is 1, if one beam is blocked, the probability that the other beam is also blocked is 97.07%. The blocking of a beam may mean that the signal strength value is equal to or lower than a threshold. When the index difference between two beams in the NLOS environment of case 2 is 11, if one beam is blocked, the other beam is not blocked (0%). Each element in Table 1 indicates the correlation between two beams having a corresponding index difference.

[0197] By comparing the LOS environment of case 1 with the LOS environment of case 2, the correlation between the beams varies depending on the number of transmit antenna ports, the half-power beamwidth, and the number of transmit beams. In some embodiments, when using the table to determine the BD of the identified beam, the terminal 630 may select the table according to at least one of the number of transmit antenna ports, the half-power beamwidth, and the number of transmit beams. The terminal 630 may determine the BD based on the selected table.

[0198] By comparing the LOS environment of case 1 with the NLOS environment of case 1, the correlation between the beams in the NLOS environment is lower than the correlation between the beams in the LOS environment. In some embodiments, when the table is used to determine the BD of the identified beam, the terminal 630 can select the table according to whether the channel environment corresponds to the LOS environment or the NLOS environment. To this end, the terminal 630 can determine whether the channel environment corresponds to the LOS environment, and determine the correlation between the beams based on the table corresponding to the determination result of whether the channel environment corresponds to the LOS environment. For example, the terminal 630 can determine whether the channel between the BS 610 and the terminal 630 corresponds to the LOS environment according to the channel impulse response (CIR) of the impulse signal sent from the BS 610. The impulse signal can be a reference signal or a separate signal defined for the CIR. The terminal 630 can determine that the first received signal is a signal sent through a path with the shortest straight-line distance. When the value of the first received signal is greater than or equal to the value of the signal received later, the terminal 630 can determine that the channel corresponds to the LOS environment. When the value of the first received signal is less than the value of the signal received later, the terminal 630 can determine that the channel corresponds to the NLOS environment. The terminal 630 may determine the BD based on the selected table according to whether the channel environment corresponds to the LOS environment or the NLOS environment.

[0199] In Table 1, the indexes of the beams are sequentially indexed from the adjacent beams. As shown in Table 1, the larger the beam index value, the closer the correlation is to 0%. On the contrary, the smaller the beam index value, the closer the correlation is to 100%. Because the beams are spaced apart from each other in the actual 3D space, the correlation is low.

[0200] Although the present disclosure has described that the terminal 630 calculates the PD value of the cell based on the BD value of the beam of the terminal 630, when the BD value of the BS of the cell is acquired, the PD value of the target cell can be calculated based on the BD value of the BS and the BD value of the terminal 630. In some embodiments, the terminal 630 can identify an available path having an RSRP greater than or equal to a threshold value among multiple paths. The terminal 630 can determine the BD value corresponding to the beam pair included in the identified available path. For example, the terminal 630 can determine the BD value of the beam included in path A and the beam included in path B based on the following equation.

[0201]

[0202] BD A，B Indicates the BD values ​​of the beam included in path A and the beam included in path B. Indicates the BD value between the beam of the terminal included in path A and the beam of the terminal included in path B. represents a BD value between a beam of a BS included in path A and a beam of a BS included in path B. Although the addition operation has been described as an example, other operations such as a multiplication operation may be used.

[0203] The terminal 630 may obtain information about the BD value of the BS in various ways. In some embodiments, the terminal 630 may obtain information about the BD value of the BS through measurement configuration information received from the serving BS 680. In other embodiments, the terminal 630 may receive a separate message from the BS and obtain information about the BD value of the BS. In other embodiments, the terminal 630 may pre-share information about the BD value of the BS. At this time, the BS may communicate with the terminal 630 through a beam in a predetermined manner.

[0204] In the present disclosure, BD may be defined in a manner different from that described above. In some embodiments, the BD between two beams (the i-th beam and the j-th beam) may be defined as a value determined based on the difference between at least one first parameter indicating (or forming) the i-th beam and at least one second parameter indicating (or forming) the j-th beam. At least one first parameter or at least one second parameter may be referred to as a beamforming parameter. For example, the beamforming parameter may include at least one of an index of a precoding codebook used in a digital end, a beamforming matrix, and a beamforming vector. In another example, the beamforming parameter may include at least one of a phase and size value of each antenna and a physical attitude control value of the antenna (e.g., a rotation amount or a tilt amount).

[0205] For example, the terminal 630 may calculate the degree of non-correlation between available paths based on the index of the codebook. The terminal 630 may calculate the degree of non-correlation from the index of the codebook indicating the beam corresponding to the available path and the configuration of the codebook. The codebook may be a codebook having a dual codebook structure for antennas in a 2D array. The index of the codebook may include an index of a first dimension (e.g., a horizontal dimension) and an index of a second dimension (e.g., a vertical dimension). For example, the index of the codebook (W) may include an index for the first codebook (W 1 )'s horizontal dimension index i 1,1 and index i for the vertical dimension 1,2 , and for the second codebook (W 2 ) index i 2 The codebook (W) can be used to index i 1,1 Function x of index i 1,2 The function y of the codebook configuration mode and the index i included in the mode 2Each index may indicate a beam direction and a component of a beam in a specific direction. The terminal 630 may determine a PMI of a beam greater than or equal to a threshold for a reference signal received from the serving BS 680 through the beam. The terminal 630 may determine a correlation between beams corresponding to available paths and a difference or index (e.g., i ) between parameters (e.g., x and y) corresponding to the determined PMI based on a specified codebook configuration. 1,1 and i 1,2 )

[0206] Although the present disclosure describes calculating the PD value of a cell based on the BD value of each beam, the PD value of a cell may be calculated without using BD. In some embodiments, the terminal 630 may receive a signal that has not been beamformed and calculate the PD value of the cell. The BS 620 to be measured may send a non-beamformed reference signal, i.e., an omnidirectional reference signal. The omnidirectional reference signal may be a signal or a type of reference signal that is separately defined for calculating the PD value. The terminal 630 may receive an omnidirectional reference signal. The reference signal transmitted through a radio channel may be received through multiple paths, and the terminal 630 may receive multiple components of the reference signal at different time points. The terminal 630 may identify a component greater than or equal to a threshold value among the multiple components of the received reference signal. The terminal 630 may determine the reception time point value of each component greater than or equal to the threshold value. The terminal 630 may determine the PD value of the cell based on the distribution of the reception time point value of each component greater than or equal to the threshold value. For example, when a relatively large number of components greater than or equal to the threshold value are distributed within a predetermined interval, the terminal 630 may determine the PD value of the corresponding cell as small. In contrast, when reference time point values ​​of many components greater than or equal to the threshold are distributed at predetermined intervals or longer, the terminal 630 may determine that the PD value of the corresponding cell is large.

[0207] Fig.10 An example of comparison between PD values ​​according to an embodiment of the present disclosure is shown.

[0208] refer to Fig.10, path set 1010 may include seven available paths. The receive beams included in the available paths associated with path set 1010 may form an angle of 30° between them. Path set 1020 may include five available paths. The receive beams included in the available paths associated with path set 1020 may form an angle of 45° between them. Path set 1030 may include three available paths. The receive beams included in the available paths associated with path set 1030 may form an angle of 90° between them. Path set 1040 may include two available paths. The receive beams included in the available paths associated with path set 1040 may form an angle of 90° between them. Path set 1050 may include two available paths. The receive beams included in the available paths associated with path set 1050 may form an angle of 45° between them. Path set 1060 may include one available path. The receive beams of terminal 630 included in the available paths associated with path set 1060 correspond to BD and may have a basic value (e.g., 0).

[0209] Referring to the above equation 4, the terminal 630 may determine that the PD value of the path set 1010 having the largest number of available paths is the largest. Since the angle formed between the two beams in the path set 1040 is greater than the angle formed between the two beams in the path set 1050, the terminal 630 may determine that the PD value of the path set 1040 is greater than the PD value of the path set 1050. This is because as the angle formed by the two beams (equal to or less than 180°) is larger, the two beams are more independent. The terminal 630 may determine that the PD value increases in the order of the path set 1010, the path set 1020, the path set 1030, the path set 1040, the path set 1050, and the path set 1060. As the number of available paths increases, the PD value has a larger value. Since the BD value of the available path has a larger value, the PD value may have a larger value.

[0210] Terminal 630 can be based on Figures 6 to 7B The best received signal value of the cell calculated in Figure 8 , Fig. 9 and Fig.10 The value representing the cell (hereinafter referred to as CRV) is determined by the PD value of the cell determined in.

[0211] In some embodiments, terminal 630 may determine CRV based on Equation 6 below.

[0212]

[0213] In Equation 6, CRV represents CRV, Best BRSRP represents the best received signal value of the cell, PathDiversity represents the PD value of the cell, and Represents the weighting factor.

[0214] By adaptively controlling the weighting factor according to the situation The characteristics of the CRV can vary. For example, when the weighting factor When the weighting factor is relatively large, it can be determined that the CRV calculated by assigning a larger weighting value to the optimal BRSRP rather than the PD. When the weighting factor is relatively large, a cell that can provide high throughput is more likely to be selected. When the weighting factor is relatively small, it is possible to determine the CRV calculated by assigning a smaller weighting value to the optimal BRSRP rather than the PD. When is relatively small, a cell that is robust to channel changes due to obstacles or terminal movement is more likely to be selected.

[0215] The best BRSRP may be an indicator value indicating the best received signal value of a cell. The reported value may be one of 98 values ​​from 0 to 97. The best BRSRP may be determined based on the following table.

[0216] Table 2

[0217]

[0218] PD may be an index indicating a PD value of a cell. In some embodiments, the index may be one of 98 values ​​from 0 to 97. The terminal 630 may normalize the PD value of the cell. For example, the terminal 630 may map the PD value of the cell to a mapping value corresponding to one of the values ​​from 0 to 97. For example, the terminal 630 may determine a mapping value corresponding to the PD value of the cell based on the following equation 7.

[0219]

[0220] In Equation 7, V mapped represents the mapping value, and V original Indicates the PD value of the cell. max Represents the larger value among the PD values ​​to be mapped by Equation 7. V min represents the minimum value among the PD values ​​to be mapped by Equation 7.

[0221] The terminal 630 may store a table including a range of 98 PD values ​​and an index corresponding thereto. The terminal 630 may calculate a specific PD based on the stored table, identify a corresponding index, and determine the CRV by the identified index. The terminal 630 may determine that the CRV is a value greater than or equal to 0 and equal to or less than 97 by controlling the optimal BRSRP and PD to be greater than or equal to 0 and equal to or less than 97.

[0222] According to various embodiments of the present disclosure, the terminal 630 may determine a representative value of a cell. For example, the representative value may be determined as Equation 6. In this case, in order to determine the representative value, it is necessary to determine a weighting factor Terminal 630 can obtain the weighting factor by various methods.

[0223] In some embodiments, terminal 630 may receive weighting factors from serving BS 680. The serving BS 680 may be a BS that supports the serving cell to provide a service to the terminal 630. The serving BS 680 may determine a weighting factor of the terminal 630. For example, the serving BS 680 may determine the weighting factor based on information about neighboring cells near the terminal 630. The information about the neighboring cells may include at least one of the frequency band information, beam information, location information, and topology information of each neighboring cell. The topology information may be a composite of information about the location of the BS supporting the neighboring cells, the connection network relationship (e.g., wireless backhaul or wired backhaul), and the direction of the supported beams. The serving BS 680 may estimate the value of the number of available paths or independent paths of the terminal 630 from the information about the neighboring cells near the terminal 630. When the number of available paths or independent paths for each neighboring cell is greater than or equal to a threshold, it may be determined that a robustness greater than or equal to a predetermined level is guaranteed. Therefore, the serving BS 680 may increase the weighting factor is determined to be relatively large so that a cell is selected based on the signal throughput.

[0224] The serving BS 680 may determine the weighting factor Provided to terminal 630. For example, serving BS 680 may Insert into the following description Fig. 12A The serving BS 680 may include the weighting factor The measurement configuration information of the serving BS 680 is sent to the terminal 630. In another example, the serving BS 680 may also send the weighting factor Sent to terminal 630.

[0225] The serving BS 680 may send a control signal to the terminal 630 instead of setting the determined weighting factor The control signal may be a signal indicating the difference between the previous weighting factor and the newly determined weighting factor. For example, the control signal may be a signal indicating one of increase, decrease and maintenance. In addition, the control signal may be a signal indicating a default value.

[0226] In other embodiments, the terminal 630 may obtain the weighting factor according to the internal configuration of the terminal 630. For example, the terminal 630 may set the weighting factor differently depending on the set to which the driven application belongs. When the driven application belongs to an application set that requires a seamless service (such as a streaming service), the terminal 630 may increase the weighting factor Set to a smaller value. This is because seamless service requires channel robustness over high signal throughput.

[0227] In another example, the terminal 630 may set the weighting factor differently depending on the detected moving speed of the terminal 630. When the terminal 630 moves relatively slowly, the weighting factor This is because the security of the channel is guaranteed due to low mobility, and thus the terminal 630 requires a high signal throughput.

[0228] In another example, the terminal 630 may set the weighting factor differently depending on the internal state of the terminal 630 (eg, the battery state or the brightness state). When the charge level of the battery of the terminal 630 is relatively low, the terminal 630 may increase the weighting factor Set small so that signals with low throughput are received.

[0229] In another example, the terminal 630 may set the weighting factor according to the setting of the user of the terminal 630. The user of terminal 630 may input the weighting factor through a user interface (UI) provided by terminal 630. The terminal 630 can set the weighting factor The terminal 630 may set the weighting factor based on the set weighting factor. To measure cell 621.

[0230] Based on the measurements, the cell with the largest CRV can be selected. For example, similar to the following Fig. 12A In the handover process in the example, the terminal 630 may send a measurement report including the measurement result of the cell 621 to the serving BS 680. The serving BS 680 may select a cell by comparing the CRV of the cell 621 with the CRV of other cells. Fig. 12B In the initial access process in , the terminal 630 can select the cell 621 as the cell to be accessed by comparing the CRV of the cell 621 with the CRVs of other cells.

[0231] Fig.11Ais a flowchart showing the operation of a terminal for determining CRV according to an embodiment of the present disclosure. The terminal may be Figure 6 Terminal 630.

[0232] refer to Fig.11A , in operation 1110, the terminal 630 may determine a signal strength value of a first cell. The first cell may be a serving cell or a neighboring cell of the terminal 630. The signal strength value may be a best received signal strength value calculated by the terminal 630 through measurement of a reference signal. The signal strength value may be a signal strength value representing the first cell. The reference signal may be a reference signal for beamforming. The reference signal may be a cell-specific reference signal (CRS), a channel state information reference signal (CSI-RS), or a demodulation reference signal (DM-RS). The terminal 630 may use different types of reference signals depending on whether an RRC connection with a serving cell is established.

[0233] The terminal 630 may acquire a signal strength value of each received reference signal. The terminal 630 may determine the best received signal value representing the first cell from the acquired signal strength value. The terminal 630 may determine the best received signal value of the first cell from the acquired signal value before performing at least one of layer 1 filtering and layer 3 filtering. For example, by calculating the maximum value of the signal strength value acquired in the k-th scanning interval, the terminal 630 may determine the best received signal value corresponding to the k-th scanning interval. After layer 3 filtering, the terminal 630 may determine the best received signal value of the first cell. For example, by performing a first calculation operation (e.g., determining a maximum value, summing, or averaging) on ​​the signal strength value corresponding to the first receiving beam of the terminal 630 at the k-th scanning interval, the terminal 630 may determine the signal strength value representing the first receiving beam. The terminal 630 may perform layer 1 filtering and layer 3 filtering on the signal strength value representing the first receiving beam. The terminal 630 may determine the signal strength value representing the first cell by performing a second calculation operation (e.g., determining a maximum value, summing, or averaging) on ​​the signal strength values ​​representing the respective receiving beams of the terminal 630 that have been subjected to layer 3 filtering. The signal strength value representing the first cell may be a best received signal value of the first cell.

[0234] In operation 1120, the terminal 630 may determine a PD value of the first cell. The PD value of the first cell may be a parameter value indicating the degree of non-correlation between paths associated with the first cell. The terminal 630 may identify an available path among a plurality of paths between the terminal 630 and the first cell, determine a BD value of a beam included in the available path, and determine the PD value of the first cell based on the determined BD value. The larger the determined BD value, the larger the PD value. The larger the number of determined BD values, the larger the PD value. For example, the terminal 630 may determine the BD based on Equation 4 or Equation 5 above.

[0235] At operation 1130, the terminal 630 may determine a representative value of the first cell based on the signal strength value and the PD value. The terminal 630 may determine the representative value of the first cell based on the weighting factor and the signal strength value and the PD value. The terminal 630 may determine a first weighting value and a second weighting value from the weighting factor. The first weighting factor may be inversely proportional to the second weighting value. The larger the first weighting value, the smaller the second weighting value. For example, when the first weighting value is When the second weighted value can be The terminal 630 may determine the representative value (ie, CRV) of the first cell by applying the first weighting value to the signal strength value and applying the second weighting value to the PD value. For example, the terminal 630 may determine the CRV of the first cell based on Equation 6 above.

[0236] Fig. 11B is a flowchart showing the operation of a terminal for cell selection according to an embodiment of the present disclosure. The terminal may be Figure 6 Terminal 630.

[0237] refer to Fig. 11B At operation 1160, the terminal 630 may obtain a representative value of the first cell. The terminal 630 may determine the representative value of the first cell based on the best received signal value and the PD value of the first cell, such as Fig.11A Described in .

[0238] In operation 1170, the terminal 630 may communicate through the selected cell based on the representative value of the first cell. For example, the terminal 630 may select a cell based on the measurement result, and send a random access signal to the selected cell for performing initial access. In another example, the terminal 630 may send a message including the measurement result to the serving BS 680, and communicate with the selected cell via the serving BS 680.

[0239] In some embodiments, a cell may be selected by the terminal 630. The terminal 630 may be a terminal before initial access. The terminal 630 may compare measurement results of multiple cells. The terminal 630 may compare the CRVs of multiple cells. The terminal 630 may select a cell having a maximum value in the CRV. This selection may also be referred to as initial cell selection. For example, when the terminal 630 is a terminal supporting CA, the BS 610 may determine that the selected cell is a primary cell (Pcell). In another example, when the terminal 630 supports DC, the BS 610 may determine that the selected cell is a Pcell of an MCG (or a second cell group).

[0240] After receiving system information from the BS supporting the selected cell, the terminal 630 may establish an RRC connection with the selected cell. After completing an access procedure with the selected cell, the terminal 630 may perform communication through the selected cell.

[0241] In other embodiments, a cell may be selected by a serving BS 680 of the terminal 630. The terminal 630 may perform a measurement reporting process. The terminal 630 may send a measurement result for each neighboring cell of the terminal 630 to the serving BS 680. The BS 680 may select a cell having a maximum value in the CRV included in the measurement result. For example, if the terminal 630 is a terminal supporting CA, the BS 680 may determine that the selected cell is a secondary cell (Scell). In another example, when the terminal 630 supports DC, the BS 680 may determine that the selected cell is an Scell ​​of a secondary cell group (SCG). In yet another example, the BS 610 may perform a handover to the selected cell.

[0242] BS 680 may transmit a control instruction to terminal 630 to perform communication through the selected cell. Terminal 630 may communicate with the selected cell based on the control instruction.

[0243] Fig. 12A An example of a measurement report according to various embodiments of the present disclosure is shown.

[0244] refer to Fig. 12A , the measurement report operation can be performed between the terminal and the BS. The terminal can be Figure 6 The BS may be a serving BS 680 of the terminal 630. Hereinafter, a case where the terminal 630 measures a neighboring cell will be described.

[0245] refer to Fig. 12A In operation 1210, the serving BS 680 may send a measurement configuration message to the terminal 630. The measurement configuration message may include measurement configuration information. The measurement configuration information may include (i) measurement object information, (ii) report configuration information, (iii) measurement identification information, (iv) quantity configuration information, and (v) measurement gap information. The measurement configuration information may also include a weighting factor for determining the CRV.

[0246] The measurement object information may indicate an object to be measured by the terminal 630. The measurement object information may indicate at least one of an intra-cell object within a cell, an inter-cell measurement object, and an inter-radio access technology (RAT) measurement object. The measurement object information may indicate a cell of a BS supporting beamforming (hereinafter, a 5G cell). The terminal 630 may measure the 5G cell. For example, the measurement object information may indicate a cell 621, which is a neighboring cell served by a neighboring BS 620, as a measurement object. The terminal 630 may select an MCG for DC by measuring the PD value of the 5G cell.

[0247] The report configuration information may indicate a report type or a report condition regarding a time point at which the terminal 630 reports the measurement result. The report type indicates the type of the measurement result. The report type may indicate whether the measurement result corresponds to a measurement based on path diversity or a measurement based on the best received signal. The report condition may be information regarding an event triggering a report of the measurement result by the terminal 630 and a period of reporting. The report condition may include a condition associated with PD. For example, the report condition may include a condition that the PD value of the serving cell is equal to or less than a threshold value. In another example, the report condition may include a condition that the PD value of the cell 621 corresponding to the neighboring cell is greater than or equal to a threshold value.

[0248] The measurement identification information may be information about a measurement identification indicating a measurement object reported by the terminal 630 when the terminal 630 reports the measurement object, and a type of report based on a link between the measurement object and the report configuration. The quantity configuration information may be parameter information about filtering of a measurement unit, a report unit, and a measurement result value. The measurement gap information may be information about a measurement gap corresponding to a portion that can be used by the terminal 630 for measurement regardless of data transmission with a serving cell.

[0249] In operation 1220, the terminal 630 may perform measurement based on the received measurement configuration information. The terminal 630 may measure the cell indicated by the measurement object information included in the measurement configuration information. For example, the terminal 630 may measure the cell 621. When the reporting condition included in the report configuration information included in the measurement configuration information is met, the terminal 630 may measure the indicated cell. For example, when the condition associated with the PD is met, the terminal 630 may measure the cell 621.

[0250] In operation 1230, the terminal 630 may report the measurement result to the serving BS 680. The message including the measurement result may be referred to as a measurement report message. The measurement report message may include a measurement identifier, a representative value of the serving cell, and a representative value of the cell 621 corresponding to the measured neighboring cell. The measurement identifier may be a measurement identifier associated with a report configuration that satisfies the reporting condition. The measurement identifier may indicate the cell 621.

[0251] Fig. 12B An example of an access procedure according to various embodiments of the present disclosure is shown.

[0252] refer to Fig. 12B , the access process can be performed between the terminal and the BS. The terminal can be Figure 6 The BS may be a BS supporting the cell selected by the terminal 630. For example, the BS may be Figure 6 Hereinafter, a case in which the terminal 630 selects a cell and accesses the selected cell will be described.

[0253] refer to Fig. 12B , in operation 1270, the terminal 630 may perform measurement. The terminal 630 may measure the neighboring cells of the terminal 630. For example, the terminal 630 may measure the cell 621. As a result of the measurement, the terminal 630 may determine the best received signal value and the PD value of each neighboring cell. The terminal 630 may determine the CRV of each neighboring cell based on each of the best received signal value and the PD value. The terminal 630 may determine the CRV of each neighboring cell by controlling the weighting factor to serve a given purpose. For example, when a cell requiring channel robustness is required, the terminal 630 may determine the CRV of each neighboring cell by applying a greater weighting value to the PD value. The terminal 630 may identify the CRV having the maximum value (hereinafter referred to as the maximum CRV) among the CRVs of the neighboring cells. The terminal 630 may select a cell corresponding to the maximum CRV among the neighboring cells.

[0254] In operation 1280, the terminal 630 may transmit a random access preamble to the BS supporting the selected cell. For example, the terminal 630 may transmit the random access preamble to the BS 620 supporting the selected cell 621. By transmitting the random access preamble, the terminal 630 may inform the BS 620 that there is an attempt to access the cell 621, and the BS 620 may estimate a delay with the terminal 630.

[0255] Figure 6 , Fig. 7A , Figure 7B , Figure 8 , Fig. 9 , Fig.10 , Fig.11A , Fig. 11B , Fig. 12A and Fig. 12B A method of determining a CRV representing a predetermined cell has been described. In the method of determining a CRV, a weighting factor may be adaptively set. For example, the weighting factor may need to be configured differently for a case where a cell is selected with a focus on cell robustness and a case where a cell is selected with a focus on cell data throughput. Fig.13 , Fig.14 , Fig.15 , Fig.16 , Fig.17 , Fig.18 , Fig.19 , Fig. 20 , Fig.21 and Fig. 22 Various embodiments are shown for selecting the best cell by adaptively controlling the weighting factor depending on the situation.

[0256] Fig.13 An example of cell selection of a terminal supporting CA according to an embodiment of the present disclosure is shown. The terminal may be Figure 6 Terminal 630.

[0257] refer to Fig.13 , the terminal 630 may be a terminal that uses two or more component carriers (CCs) to support CA technology to support a wide transmission bandwidth. The two or more CCs may include a primary component carrier (PCC) and a secondary component carrier (SCC). In the PCC, a cell that provides service to the terminal 630 may be referred to as a Pcell. In the SCC, a cell that provides service to the terminal 630 may be referred to as a Scell. The Pcell and the Scell ​​may be used as serving cells.

[0258] refer to Fig.13 , the wireless communication environment 1300 may be a wireless communication environment including a terminal 630 supporting CA. The wireless communication environment 1300 may include a BS 1310 and a BS 1320. The BS 1310 may provide a service to a cell 1311. The BS 1320 may provide a service to a cell 1321. The cell 1311 may provide a path 1355, a path 1356, and a path 1357 to a terminal 630 located at a position 1333. The cell 1321 may provide a path 1351 to a terminal 630 located at a position 1333.

[0259] When the terminal 630 does not have a serving cell (e.g., in idle mode), the terminal 630 may perform a cell search in order to select a cell. The terminal 630 may select a cell with a maximum measurement value among the cells found. The measurement value may be a CRV representing the cell found. The selected cell may be a Pcell. The terminal 630 may receive system information of the cell from a BS supporting the selected cell. The terminal 630 may access the selected cell through a random access operation with the BS. In order to establish an RRC connection with the selected cell, the terminal 630 may send or receive control signaling to or from the BS supporting the selected cell. When the Pcell is selected, the terminal 630 may send or receive control information such as system information, control signals, random access preambles, and random access responses to or from the BS. The transmission of control information may require robustness against changes in channel states. Therefore, when selecting a Pcell, the terminal 630 may be required to select a cell with relatively high robustness to channel changes.

[0260] The terminal 630 may select a cell having a maximum value among the CRVs of the cells. The terminal 630 may determine the CRV of each cell by applying a weighting value to the PD that is greater than the weighting value applied to the received signal value for each cell. This is because the transmission of control information should centrally consider the PD in order to prevent the generation of problems such as transmission delays due to transmission obstructions (e.g., RLF or recovery). For example, the terminal 630 may set the weighting factor in the above equation 6 to be relatively small. The weighting factor may have a value less than 0.5. The terminal 630 may select the cell 1311 having a larger PD value between the cells 1311 and 1321.

[0261] When the terminal 630 has a serving cell, the terminal 630 may perform a measurement report in order to increase the transmission rate by adding a cell. The terminal 630 may report the measurement result to a BS supporting the serving cell (hereinafter referred to as a serving BS). The serving BS may select a cell having a maximum measurement value among the measurement values ​​of the neighboring cells of the terminal 630 received from the terminal 630. The measurement value may be a CRV included in the measurement report. The selected cell may be a Scell. When the Scell ​​already belongs to the serving cell, the selected cell may be provided to the terminal 630 as an additional Scell ​​to provide services. The terminal 630 may send or receive a larger amount of data through the selected or added Scell. Compared with control information transmission, general data transmission may require a higher data transmission rate while requiring relatively lower robustness. Therefore, when selecting or adding a Scell, the serving BS may be required to select a cell having relatively high data transmission and data throughput.

[0262] The serving BS may select a cell having a maximum value among the CRVs of the cells. The terminal 630 may determine the CRV of each cell by applying a larger weighting value to the best received signal value of each cell rather than to the weighting value applied to the PD of each cell. This is because data transmission focuses on the transmission volume, throughput, and output volume rather than the error problem caused by the transmission block of the control information. In addition, the Scell ​​may be added / released relatively more easily than the Pcell, so the throughput may be focused differently from the Pcell. For example, the terminal 630 may set the weighting factor in equation 6 to be relatively large. The weighting factor may have a value greater than 0.5. The serving BS may select the cell 1321 of the path 1351 having a higher priority of RSRP between the cells 1311 and 1321. When the serving BS is the BS 1310 supporting the cell 1311, the CA may be referred to as intra-eNB CA. When the serving BS is different from the BS 1310 supporting the cell 1311, the CA may be referred to as inter-eNB CA.

[0263] Hereinafter, for the convenience of description, when determining the CRV of each neighboring cell, when the first weighted value applied to the best received signal value of the cell is greater than the second weighted value applied to the PD value of the cell, the operation mode of the terminal 630 may be referred to as a cell selection mode based on the best received signal. Conversely, when the first weighted value is less than the second weighted value, the operation mode of the terminal 630 may be referred to as a cell selection mode based on path diversity. However, the terminology does not limit the detailed operation of the terminal 630. The operation of one of the operation modes does not need to be determined by the terminal 630. The terminal 630 may adaptively set the weighting factor depending on the situation. According to the internal setting of the terminal 630, the number of candidates for the weighting factors may be two or more.

[0264] Fig.14 is a flowchart showing the operation of cell selection of a terminal supporting CA according to an embodiment of the present disclosure. The terminal may be Figure 6 The following describes the terminal 630 based on Fig.13 Operation of a hypothetical terminal 630 in the wireless communication environment 1300 is described below.

[0265] refer to Fig.14 In operation 1410, the terminal 630 may set the operation mode to a cell selection mode based on path diversity before initial access. By setting the weighting factor to be small, the terminal 630 may set the weighting value to be applied to the PD value to be greater than the weighting value to be applied to the best received signal value.

[0266] In operation 1420, the terminal 630 may perform beam scanning. The terminal 630 may receive a reference signal from a neighboring cell through a beam scanning operation. The reference signal may be a beam-formed reference signal. The terminal 630 may calculate the best received signal value of each cell from the received reference signal. For example, Figure 6 , Fig. 7A and Figure 7B In the manner described in , the terminal 630 can calculate the best received signal value of each cell. The terminal 630 can identify at least one available path based on the reference signal received from the cell. The terminal 630 can determine the BD value of at least one identified available path. The terminal 630 can determine the PD value of each cell from the determined BD value. The terminal 630 can determine the CRV of each cell based on the calculated best received signal value and the PD value. When the number of neighboring cells of the terminal 630 is N, the terminal 630 can determine N CRVs corresponding to each neighboring cell.

[0267] In operation 1430, the terminal 630 may select a Pcell. The terminal 630 may identify the maximum CRV among the CRVs acquired as a result of the beam scanning in operation 1420. The terminal 630 may select a cell corresponding to the maximum CRV as the Pcell. Currently, the operation mode of the terminal 630 is a cell selection mode based on path diversity, and thus the selected Pcell may be a cell selected when the PD value is centrally considered.

[0268] In operation 1440, the terminal 630 may identify whether CA is supported. When CA is not supported, the terminal 630 may end the operation for additional cell selection. The Pcell is provided to the terminal 630 as a single cell. When CA is supported, the terminal 630 may perform operation 1450. The terminal 630 may perform operation 1450 to select an Scell.

[0269] In operation 1450, the terminal 630 may set the operation mode to the cell selection mode based on the best received signal. When the previous operation mode of the terminal 630 is the cell selection mode based on path diversity, the terminal 630 may change the weighting factor. By setting the weighting value relatively large, the terminal 630 may assign a weighting value to be applied to the best received signal value greater than the weighting value to be applied to the PD value.

[0270] In operation 1460, the terminal 630 may determine a CRV for selecting a Scell.

[0271] In some embodiments, the terminal 630 may measure each neighboring cell to select an Scell. The terminal 630 may determine the CRV of each neighboring cell based on the measurement. Different from the value used to select the Pcell, the newly applied weighting factor may be a value that applies a higher weighting value to the best received signal value of each cell than the weighting value applied to the PD value of each cell. In other embodiments, the terminal 630 may determine the CRV for selecting the Scell ​​based on the value calculated when selecting the Pcell or another Scell. For example, the terminal 630 may newly calculate the CRV of each cell based on the best received signal and PD value of each neighboring cell obtained when selecting the Pcell and the newly set weighting factor. The terminal 630 may report the calculated CRV to the serving BS providing the Pcell.

[0272] Although not in Fig.14 , but the serving BS may select an Scell ​​based on the reported CRV to provide service to the terminal 630. The serving BS may select a cell corresponding to the maximum CRV as the Scell. When a supported Scell ​​already exists, the serving BS may add the selected Scell.

[0273] although Fig.14 Operations 1410 to 1460 are shown to be performed sequentially, but some operations may be omitted or the next operation may be performed after a considerable amount of time has passed. For example, when the terminal 630 has a serving cell, the terminal 630 may not perform operations 1410 to 1430. In addition, when the serving cell includes a Pcell and an Scell, the terminal 630 may only perform operations 1450 to 1460 without performing operations 1410 to 1440 in order to add the Scell. In another example, when the condition for selecting the Scell ​​is not satisfied after operation 1450, the terminal 630 may perform operation 1460 after a considerable amount of time has passed.

[0274] Fig.15 An example of a cell group and cell selection for a terminal supporting DC according to an embodiment of the present disclosure is shown. The terminal may be Figure 6 Terminal 630.

[0275] refer to Fig.15BSs can be divided into macro BSs, micro BSs, and femto BSs according to their coverage areas. A macro BS may be a BS that provides a cell (hereinafter referred to as a macro cell) in a relatively wide area compared to a micro BS or a femto BS. A micro BS or a femto BS may be referred to as a small BS. A cell of a small BS may be referred to as a small cell. The terminal 630 may receive services through a macro cell and a plurality of small cells. In order to solve problems occurring due to switching between a plurality of small cells, the terminal 630 may support a DC technology for dividing a BS responsible for control signaling (hereinafter referred to as a master eNB (MeNB)) and a BS responsible for data transmission (hereinafter referred to as a secondary eNB (SeNB)).

[0276] refer to Fig.15 , the wireless communication environment 1500 may be a wireless communication environment including a terminal 630 supporting DC. The wireless communication environment 1500 may include a BS 1510 and a BS 1520. The BS 1510 may provide a service to a cell 1511. The BS 1520 may provide a service to a cell 1521. The cell 1511 may provide a path 1555, a path 1556, and a path 1557 to a terminal 630 located at a position 1533. The cell 1521 may provide a path 1551 to a terminal 630 located at a position 1533.

[0277] When the terminal 630 does not have a serving cell (e.g., in idle mode), the terminal 630 may perform a cell search in order to select a cell. The terminal 630 may select a cell having a maximum measurement value among the found cells. The measurement value may be a CRV representing the found cell. The terminal 630 may set the BS supporting the selected cell as the MeNB. The cell may be a Pcell. Fig.13 As described in, when selecting a Pcell, the terminal 630 may be required to select a cell with relatively high robustness to channel changes. When determining the CRV of each cell, the terminal 630 may determine the CRV by applying a higher weighting value to the PD of each cell than the weighting value applied to the best received signal value. For example, the terminal 630 may set the weighting factor in the above equation 6 to be relatively small. The terminal 630 may select the cell 1511 with a larger PD value between cells 1521 and 1511. When selecting cell 1511, the terminal 630 may set BS 1510 to be a MeNB. When the terminal 630 is a terminal supporting CA, another cell (not shown) other than the cell 1511 provided by the MeNB may be additionally set in the terminal 630. The other cell may be a Scell. The service cell group (cell 1511 and other cells) provided by the MeNB may be referred to as an MCG. The MCG may include one Pcell and at least one Scell.

[0278] After setting up the MeNB, the terminal 630 may perform a measurement report in order to set up the SeNB. The terminal 630 may report the measurement result to the MeNB (e.g., BS1510). The MeNB may select the SeNB based on the measurement report of the neighboring cell of the terminal 630 received from the terminal 630. The SeNB may be a BS configured to manage additional radio resources for increasing the amount of output data. However, the SeNB has a scheduler for managing resources different from those of the MeNB, so the MeNB may select a primary secondary cell (PScell) of the SeNB, such as the Pcell of the MeNB, for performing random access. The PScell ​​is used to send control information that needs to be robust to channel changes, and the terminal 630 may determine the CRV of each cell by applying a higher weighting value to the PD of each cell than the weighting value applied to the optimal received signal value as the measurement result of the measurement report. For example, the MeNB1510 may set the BS1520 as the SeNB.

[0279] The other cells (Scell) of the SeNB have the purpose of increasing the amount of output data, and the MeNB may need to select a cell with a relatively high data transmission rate and a relatively high data output amount when selecting or adding a cell. As a measurement result of the measurement report, the terminal 630 can determine the CRV of each cell by applying a weighting value greater than the weighting value applied to the PD value of each cell to the best received signal value. The terminal 630 can select the Scell ​​based on a value different from the weighting factor used when selecting the Pcell or PScell. For example, the MeNB 1510 can select the cell 1521 as the Scell ​​of the SeNB. The service cell group (PScell ​​and cell 1521) provided by the SeNB can be called an SCG. The SCG may include one PScell ​​and at least one Scell.

[0280] The detailed operation for selecting the Scell ​​of the SeNB is as follows. The MeNB of the terminal 630 corresponds to the BS 1510, and the SeNB of the terminal 630 corresponds to the BS 1520. Fig.15 Although not shown in FIG. 1 , the terminal 630 may measure neighboring cells in order to select the Scell ​​of the SeNB. The terminal 630 may report the measurement result to the BS 1510 .

[0281] In operation 1581, the BS 1510 may determine whether to add, delete, or change the Scell ​​of the SeNB based on the measurement report received from the terminal 630. Hereinafter, the operation of adding the Scell ​​will be described. When adding the Scell ​​of the SeNB, the BS 1510 may send an indication message for indicating the addition to the BS 1520 corresponding to the SeNB. The indication message may contain the current configuration information of the terminal 630, the Evolved Packet System (EPS) bearer information, and the information requested to the BS 1520.

[0282] In operation 1582, the BS 1520 may transmit a request message for adding an Scell ​​to the BS 1510. The request message may contain information on a cell to be added to the terminal 630 and information on a bearer of the terminal 630 (hereinafter, referred to as an offload bearer).

[0283] When BS 1510 receives the request message, it may add the Scell ​​of BS 1520 to the terminal 630 in operation 1583. In order to set the offload bearer, BS 1510 may send an RRC connection reconfiguration message to the terminal 630. The RRC connection reconfiguration message may include information about the Scell ​​of BS 1520. In addition, the RRC connection reconfiguration message may also include information about the offload bearer between the terminal 630 and BS 1520.

[0284] When the addition of the Scell ​​of the BS 1520 is completed, the terminal 630 may transmit an RRC connection reconfiguration complete message to the BS 1510 in operation 1584 .

[0285] When the BS 1510 receives the RRC connection reconfiguration complete message, the BS 1520 may send a confirmation message indicating completion of the addition of the SCG to the BS 1510 in operation 1585 .

[0286] In operation 1586, the terminal 630 may perform a random access procedure with the PScell ​​of the BS 1520. The terminal 630 may synchronize the newly added Scell ​​of the BS 1520 and set the transmission output through the random access procedure. The terminal 630 may transmit and receive data to and from the BS 1520 through the Scell. Operation 1586 may be performed independently of the operation (e.g., operation 1584 and operation 1585) indicating completion of the RRC connection reconfiguration. Therefore, operation 1586 may be performed before operation 1585.

[0287] For example, when the terminal 630 selects a cell (Pcell) for configuring the MeNB or when the MeNB selects a cell for configuring the PScell ​​of the SeNB, the terminal 630 may operate in a cell selection mode based on path diversity. Conversely, when the MeNB selects a cell for configuring the Scell ​​of the MeNB or SeNB, the terminal 630 may operate in a cell selection mode based on the best received signal.

[0288] Fig.16 is a flowchart illustrating operations for selecting a cell group and a cell of a terminal supporting DC according to various embodiments of the present disclosure. The terminal may be Figure 6 Terminal 630.

[0289] refer to Fig.16 , will be based on Fig.15 The wireless communication environment 1500 is assumed to be described as follows Fig.16 The operation of terminal 630 is shown in FIG.

[0290] refer to Fig.16 In operation 1610, the terminal 630 may set the operation mode to the PD-based cell selection mode before initial access. That is, by setting the weighting factor to be small, the terminal 630 may set the weighting value to be applied to the PD value to be greater than the weighting value to be applied to the best received signal value.

[0291] In operation 1620, the terminal 630 may perform beam scanning. The terminal 630 may receive a reference signal from a neighboring cell through a beam scanning operation. The reference signal may be a beam-formed reference signal. The terminal 630 may calculate the best received signal value of each cell from the received reference signal.

[0292] In operation 1630, the terminal 630 may select a Pcell. The terminal 630 may identify the maximum CRV among the CRVs acquired as a result of the beam scanning in operation 1620. The terminal 630 may select a cell corresponding to the maximum CRV as the Pcell. Currently, the operation mode of the terminal 630 is a cell selection mode based on path diversity, and thus the selected Pcell may be a cell selected when the PD value is centrally considered.

[0293] In operation 1640, the terminal 630 may select a BS supporting the Pcell as the MeNB. The terminal 630 may identify a group of serving cells provided by the MeNB as the MCG.

[0294] In operation 1650, the terminal 630 may identify whether DC is supported. When DC is not supported, the terminal 630 may end the cell selection operation for selecting the SeNB. The Pcell is a single cell, and the BS of the Pcell may be provided as a serving BS to the terminal 630. When DC is supported, the terminal 630 may perform operation 1660. The terminal 630 may perform operation 1660 to select a cell of the SeNB.

[0295] In operation 1660, the terminal 630 may select a PScell. Currently, the operation mode of the terminal 630 is a cell selection mode based on path diversity, and thus the selected PScell ​​may be a cell selected while centrally considering the PD value.

[0296] In operation 1670, the terminal 630 may set the operation mode to a cell selection mode based on the best received signal. When the previous operation mode of the terminal 630 is a cell selection mode based on path diversity, the terminal 630 may change the weighting factor. In order to select the Scell, by setting the weighting factor to be relatively large, the terminal 630 may assign a weighting value to be applied to the best received signal value greater than the weighting value to be applied to the PD value. This is because the purpose of the Scell ​​is to increase data throughput and increase the data rate.

[0297] In operation 1680, the terminal 630 may determine a CRV for selecting an Scell. The terminal 630 may measure each neighboring cell to select an Scell. The terminal 630 may determine the CRV of each neighboring cell based on the measurement. Unlike the value used when selecting a PScell, the newly applied weighting factor may be a value that applies a weighting value greater than the weighting value applied to the PD of each cell to the best received signal value. The terminal 630 may determine the CRV for selecting an Scell ​​based on a value calculated when selecting a Pcell, a PScell, or another cell. For example, the terminal 630 may newly calculate the CRV of each neighboring cell based on the PD value of each neighboring cell acquired when selecting a Pcell, the best received signal value, and the newly set weighting factor. The terminal 630 may report the calculated CRV to the MeNB.

[0298] Although not in Fig.16 However, the MeNB may select a Scell ​​based on the reported CRV to provide service to the terminal 630. The MeNB may select a cell corresponding to the maximum CRV as the Scell. When there is an already supported Scell, the MeNB may add the selected Scell.

[0299] although Fig.16Operations 1610 to 1680 are shown to be performed sequentially, but some operations may be omitted, or the next operation may be performed after a considerable time has passed.

[0300] Fig.17 An example of selecting a RAT supporting MCG according to various embodiments of the present disclosure is shown.

[0301] refer to Fig.17 , the wireless communication environment 1700 and the wireless communication environment 1750 may include BS1710, BS1720 and terminal 630. BS1710 may provide services to cell 1711. BS1720 may provide services to cell 1721. Terminal 630 may be a terminal supporting DC. BS1710 and BS1720 may be BSs providing different RATs. For example, BS1710 may be a BS supporting a RAT based on beamforming. BS1710 may be referred to as a 5G BS. BS1720 may be a BS supporting an omnidirectional RAT. BS1720 may be referred to as a fourth generation (4G) BS.

[0302] DC may be required to set the BS so that the MeNB and SeNB are distinguished from each other. The RAT supported by the MeNB and the RAT supported by the SeNB may be different RATs. In the following, for ease of description, the RAT based on beamforming is referred to as the first RAT. The first RAT may indicate a RAT associated with the fifth generation mobile communication. The omnidirectional RAT is referred to as the second RAT. The second RAT may indicate a RAT associated with the fourth generation mobile communication. The first RAT and the second RAT have different RF structures or standards. In addition, the first RAT is a RAT based on beamforming, and a signal may be sent according to a directional characteristic in order to achieve high throughput and low delay speed. However, due to the directional characteristics, the signal strength and signal quality values ​​change sensitively according to channel state changes (such as detection of obstacles or movement of terminals). Therefore, the first RAT provides relatively low robustness. In contrast, the second RAT is an omnidirectional RAT, and signals may be sent in all directions in order to provide relatively low throughput and high delay speed. However, due to the omnidirectional characteristics, the received signal strength and signal quality values ​​change within a narrow width for channel state changes such as detection of obstacles or movement of terminals. The second RAT provides relatively high robustness.

[0303] The MCG corresponding to the serving cell group of the MeNB may be responsible for RRC signaling and control signaling, such as the random access procedure, and therefore may need to be robust to channel changes. Therefore, the terminal 630 may set the BS supporting the second RAT as the MeNB. However, when the BS supporting the second RAT is always set as the MeNB, even if the serving cell of the BS supporting the first RAT has a higher PD value than the serving cell of the BS supporting the second RAT, the terminal 630 may perform control signaling through the second RAT, resulting in inefficiency. This is because the first RAT is more robust to channel changes than the second RAT. Therefore, when measuring a cell to determine the MeNB or MCG, the PD value of the cell of the first RAT may need to be considered.

[0304] The terminal 630 may acquire a PD value for each cell (i.e., a 5G cell) supporting the first RAT. The terminal 630 may identify the maximum PD value among the acquired PD values. When the maximum PD value is greater than a threshold value, the terminal 630 may set the BS supporting the corresponding 5G cell as a MeNB. For example, the terminal 630 may be a terminal included in the wireless communication environment 1700. The terminal 630 may determine the cell corresponding to the maximum PD value of the 5G cell as the cell 1711. The terminal 630 may determine that the PD value of the cell 1711 including three available paths is greater than a threshold value. The terminal 630 may set the BS 1710 as a MeNB.

[0305] When the maximum PD value is not greater than the threshold, the terminal 630 may set the BS supporting the 4G cell as the MeNB. The terminal 630 may measure the best RSRP value of the 4G cell and set the BS supporting the cell corresponding to the maximum RSRP value as the MeNB. For example, the terminal 630 may be a terminal included in the wireless communication environment 1750. The terminal 630 may determine that the cell corresponding to the maximum PD value of the 5G cell is the cell 1711. The terminal 630 may determine that the PD value of the cell 1711 including one available path is not greater than the threshold. The terminal 630 may determine that the cell corresponding to the maximum RSRP value among the best RSRP values ​​of the 4G cell is the cell 1721. The terminal 630 may set the BS 1710 as the MeNB.

[0306] Even in control signaling, the terminal 630 can obtain the effect of obtaining high throughput and low-delay services, which are advantages of the beamforming-based RAT, by selecting the MeNB in ​​consideration of the PD value of each cell supporting the beamforming-based RAT.

[0307] Fig.18 is a flowchart illustrating an operation of a terminal for selecting a RAT supporting MCG according to various embodiments of the present disclosure. The terminal may be Figure 6 Terminal 630.

[0308] refer to Fig.18 , will be based on Fig.17 The operation of the terminal 630 is described on the assumption of the wireless communication environment 1700 or the wireless communication environment 1750.

[0309] refer to Fig.18 , in operation 1810, the terminal 630 may measure the PD value of each 5G cell. The terminal 630 may identify an available path greater than or equal to a threshold value among multiple paths of a 5G cell. The terminal 630 may determine the PD value of the 5G cell based on the BD value of the identified available path. For example, the terminal 630 may determine the PD value according to the above equation 6. In this way, the terminal 630 may obtain the PD value of the neighboring 5G cell.

[0310] In operation 1820, the terminal 630 may determine a maximum PD value. The terminal 630 may identify a maximum value among the PD values ​​of the 5G cells acquired in operation 1810. The terminal 630 may determine the identified value as the maximum PD value.

[0311] In operation 1830, the terminal 630 may determine whether the identified maximum PD value is greater than a threshold value. The threshold value may be a value that guarantees robustness at a predetermined level or higher for changes in channel states according to the movement of the terminal or the presence of obstacles. The threshold value may be a predetermined constant. The constant may be set as high as possible, because robustness at a predetermined level or higher should be guaranteed even in the case of the maximum change in channel state. The constant may be pre-stored in the terminal 630 during manufacturing and design. The threshold value may also be a variable that may be adaptively controlled. The threshold value may be a value determined according to the interference or noise intensity around the terminal 630.

[0312] When the identified maximum PD value is greater than the threshold value, the terminal 630 may perform operation 1840. When the identified maximum PD value is not greater than the threshold value, the terminal 630 may perform operation 1860.

[0313] In operation 1840, the terminal 630 may set a BS supporting a 5G cell corresponding to the identified maximum PD value as a MeNB. At least one cell and a 5G cell that may be provided by the MeNB to the terminal 630 are included in the MCG.

[0314] In operation 1850, the terminal 630 may determine the CRV of each serving cell included in the MCG. The terminal 630 may determine the CRV based not only on the PD value acquired in operation 1810 but also on the best received signal value and the weighting factor. The terminal 630 may select the maximum CRV (hereinafter referred to as the maximum representative value) among the CRVs of the serving cells included in the MCG. The terminal 630 may set the cell corresponding to the maximum representative value as the Pcell.

[0315] In operation 1860, the terminal 630 may set the BS supporting the 4G cell as the MeNB. The terminal 630 may measure the RSRP values ​​of the 4G cells near the terminal 630. The terminal 630 may identify the cell having the largest RSRP value among the RSRP values. The terminal 630 may set the BS supporting the identified cell as the MeNB.

[0316] In operation 1870, the terminal 630 may determine the CRV for selecting the Scell. In the case where the 5G BS is set as the SeNB, the terminal 630 may determine the CRV of each 5G cell so that the 5G cell with the maximum received signal value is selected as the Scell ​​for high data output and fast data rate. The terminal 630 may set the weighting factor to be greater than a reference value (e.g., 0.5) and operate in a cell selection mode based on the best received signal. The terminal 630 may set the weighting factor to apply a larger weighting value to the best received signal value than the weighting value applied to the PD value.

[0317] Although only described based on 4G and 5G Fig.17 and Fig.18 , but they are only examples for convenience of description, and the present disclosure is not limited thereto. A RAT supporting Code Division Multiple Access (CDMA) or a RAT supporting Wideband CDMA (WCDMA), which is a communication scheme earlier than 4G, may be used.

[0318] Fig.19 An example of application-based cell selection according to an embodiment of the present disclosure is shown.

[0319] refer to Fig.19 , the application can be Figure 6 The application may be an application executed by the terminal 630. For example, the application may be an application that is being run by the terminal 630 or is expected to be run by the terminal 630. The application may be an application that provides communication services to another electronic device (e.g., a server or a terminal) through a network. The terminal 630 may need to access a cell in order to run the application.

[0320] refer to Fig.19, the wireless communication environment 1900 may include BS 1910, BS 1920, and terminal 630. BS 1910 may provide a service to cell 1911. BS 1920 may provide a service to cell 1921. Cell 1911 may provide path 1955, path 1956, and path 1957 to terminal 630. Cell 1921 may provide path 1951 to terminal 630. Hereinafter, it is assumed that the best received signal value becomes larger in the order of a signal received through path 1951, a signal received through path 1955, a signal received through path 1966, and a signal received through path 1957.

[0321] The terminal 630 may classify applications into two groups. The terminal 630 may classify applications required for providing real-time services into the first group 1960, and classify applications not required for providing real-time services into the second group 1970. For example, the terminal 630 may insert an application providing a call connection into the first group. The terminal 630 may insert an application providing a streaming service such as a video into the first group 1960. The first group 1960 may include an application providing a video call service, a mobile game application based on user participation, or an application using a universal datagram protocol (UDP).

[0322] In another example, the terminal 630 may insert an application that provides a service for downloading data from another electronic device (e.g., File Transfer Protocol (FTP) or Peer-to-Peer (P2P) file sharing) into the second group 1970. The second group 1970 may further include a social network service (SNS) application, an application that provides a chat service (e.g., a messenger service) to another user, an application that provides a cloud service, or an application that uses a transmission control protocol (TCP).

[0323] Applications required to provide real-time services need to minimize problems such as RLF or transmission delays. Therefore, in order to select a cell serving an application included in the first group 1960, PD may be considered intensively. When determining the CRV of each cell, the terminal 630 may determine the CRV by applying a weighted value greater than a weighted value applied to the best received signal value to the PD of each cell. The operation mode of the terminal 630 may be a cell selection mode based on path diversity.

[0324] In contrast, an application that is not required for providing a real-time service may be required to transmit a relatively large amount of data and have a fast data transmission speed. Therefore, in order to select a cell serving an application included in the second group 1970, the best received signal strength value may be considered. When determining the CRV of each cell, the terminal 630 may determine the CRV by applying a weighted value greater than a weighted value applied to the PD value of the cell to the best received signal value. The operation mode of the terminal 630 may be a cell selection mode based on the best received signal.

[0325] The terminal 630 may acquire information about an application that is running or expected to run. The terminal 630 may identify a group including an application. For example, the terminal 630 may identify a first group 1960 including an application. The terminal 630 may determine a weighting factor according to the identified group. For example, when the second group 1970 is identified, the terminal 630 may determine the weighting factor to be 0.9, which is greater than 0.5. The terminal 630 may determine the CRV of the neighboring cell according to the determined weighting factor.

[0326] A cell may be selected based on the determined CRV. A subject of selecting a cell may vary depending on a state of the terminal 630. Depending on the state of the terminal 630, a cell may be selected by the terminal 630 or by a serving BS 680 of the terminal 630.

[0327] In some embodiments, when there is no RRC connection, the terminal 630 can select a cell for initial access. The terminal 630 can select a cell corresponding to the maximum CRV among the CRVs of the respective cells. For example, when a weighting factor in a cell selection mode based on path diversity is set for a service of an application included in the first group 1960, the terminal 630 can select a cell 1911 having a relatively large PD value. In another example, when a weighting factor in a cell selection mode based on a best received signal is set for a service of an application included in the second group 1970, the terminal 630 can select a cell 1921 having a relatively large best received signal value.

[0328] In other embodiments, when there is an RRC connection with the terminal 630, the serving BS 680 may select a cell that provides service to the terminal 630. The terminal 630 may be in a state in which one or more serving cells are set. The serving BS 680 may determine the application being run by the terminal 630. The serving BS 680 may obtain application information of the determined application. The application information may include application type, requirements, or quality of service (QOS) information. The QOS information may include a quality class indicator (QCI), an allocation and reservation priority (ARP), a guaranteed bearer rate (GBR), and a maximum bit rate (MBR). The terminal 630 may obtain information about the EPS bearer to send the service of the determined application.

[0329] The serving BS 680 may select a cell to provide the service of the application based on the acquired application information or information about the EPS bearer. For example, when the QCI of the application is 1, the serving BS 680 may recognize that the application is an application for voice service purposes. The serving BS 680 may select a cell by assigning a larger weight value to the PD value than the best received signal value.

[0330] The serving BS 680 may select a desired cell according to various schemes. For example, when the serving BS 680 obtains the PD value of each serving cell, the serving BS 680 may select a cell with a large PD value in the serving cell for voice service. In another example, when the serving BS 680 desires to add a serving cell, the serving BS 680 may provide a weighting factor corresponding to a cell selection mode based on path diversity to the terminal 630 for voice service. The weighting factor may be determined based on at least one of the QCI, ARP, GBR, and MBR included in the application information. In a corresponding example, the QCI may be 1, indicating a voice chat service. The terminal 630 may calculate the CRV of the neighboring cell according to the weighting factor. The terminal 630 may report the CRV to the serving BS 680. The serving BS 680 may select the cell 1911. The serving BS 680 may provide the terminal 630 with a voice service through the selected cell 1911.

[0331] Fig. 20 is a flowchart illustrating the operation of a terminal for application-based cell selection according to an embodiment of the present disclosure. The terminal may be Figure 6 Terminal 630.

[0332] refer to Fig. 20 , will be based on Fig.19 The operation of the terminal 630 is described on the assumption of the wireless communication environment 1900.

[0333] refer to Fig. 20 In operation 2010, the terminal 630 may acquire application information. The application information may be information about an application that is running or expected to be running in the terminal 630. The application information may include parameters indicating the type and requirements of the service provided by the application. For example, the application information may include information about the application QOS.

[0334] In operation 2020, the terminal 630 may determine whether the application requires a seamless service based on the acquired application information. When the application requires a seamless service, the terminal 630 may perform operation 2030. For example, the terminal 630 may determine that the application is included in the first group 1960. When the application does not require a seamless service, the terminal 630 may perform operation 2040. For example, the terminal 630 may determine that the application is included in the second group 1970.

[0335] In operation 2030, the terminal 630 may determine a weighting factor for the cell selection mode based on path diversity. In the calculation of CRV, the terminal 630 may set the weighting factor so that a larger weighting value is applied to the PD value than the weighting value to be applied to the best received signal value. For example, the weighting factor may be less than 0.5.

[0336] In operation 2040, the terminal 630 may determine a weighting factor for the cell selection mode based on the best received signal. In the calculation of the CRV, the terminal 630 may set the weighting factor so that a greater weighting value is applied to the best received signal value than the weighting value to be applied to the PD value. For example, the weighting factor may be greater than 0.5.

[0337] In operation 2050, the terminal 630 may determine the CRV. The terminal 630 may determine the CRV of the neighboring cell according to the determined weighting factor. For example, the terminal 630 may calculate the CRV based on the above equation 6. Fig. 20 , but the terminal 630 may perform the access procedure by reporting each determined CRV to the serving BS 680 or selecting a cell having a maximum value among the determined CRVs.

[0338] Despite Fig.19 and 20 The above description is based on two groups including a first group 1960 as an application group corresponding to a cell selection mode based on path diversity and a second group 1970d as an application group corresponding to a cell selection mode based on the best received signal, but the present disclosure is not limited thereto. The number of application groups may be three or more. The terminal 630 may identify a group corresponding to the running application in the three or more groups, and set a weighting factor corresponding to the identified group in order to measure the cell. The terminal 630 may store a table including three or more groups and weighting factors corresponding to the respective groups.

[0339] The serving BS 680 may also identify a group corresponding to an application running in the three or more groups and determine a weighting factor corresponding to the identified group. The BS 680 may store a table including three or more groups and weighting factors corresponding to the respective groups. The serving BS 680 may select a cell according to the determined weighting factor. For example, the serving BS 680 may recalculate the CRV of the reported serving cell according to the previous weighting factor. In another example, the serving BS 680 may send measurement configuration information to the terminal 630 to perform measurements for cell addition by the determined weighting factor.

[0340] Fig.21 An example of cell selection based on the movement of a terminal according to an embodiment of the present disclosure is shown. The terminal may be Figure 6 Terminal 630.

[0341] refer to Fig.21, the wireless communication environment 2100 and the wireless communication environment 2150 may include BS 2110, BS 2120, and terminal 630. BS 2110 may provide service to cell 2111. BS 2120 may provide service to cell 2121. Cell 2111 may provide path 2155, path 2156, and path 2157 to terminal 630. Cell 2121 may provide path 2151 to terminal 630. Hereinafter, it is assumed that the best received signal value becomes larger in the order of a signal received through path 2151, a signal received through path 2155, a signal received through path 2156, and a signal received through path 2157. In the wireless communication environment 2100, a user 2130 of terminal 630 is walking through an overlapping area between cell 2111 and cell 2121. In the wireless communication environment 2150, terminal 630 is passing through an overlapping area between cell 2111 and cell 2121 by car 2180.

[0342] As the terminal 630 moves, the channel state between the cell 2111 or the cell 2121 and the terminal 630 may change. The degree of change in the channel state may be inversely proportional to the robustness of the cell providing the channel. The degree of change in the channel state may vary depending on the mobility level of the terminal 630. Therefore, the terminal 630 may determine the mobility level of the terminal 630 and obtain information about the degree of robustness required for the cell.

[0343] In some embodiments, the terminal 630 may determine the mobile level of the terminal 630 by calculating the Doppler shift value. The terminal 630 may determine the mobile level of the terminal 630 based on how much the Doppler effect video frequency changes due to the movement of the terminal 630. In other embodiments, the terminal 630 may determine the mobile level of the terminal 630 by measuring the frequency of handover or cell reselection per unit time. The terminal 630 may determine the mobile level of the terminal 630 by calculating the number of handovers or cell reselections during a predetermined interval and dividing the calculated number of handovers or cell reselections by the time value corresponding to the predetermined interval. In other embodiments, the terminal 630 may include a separate device for measuring the moving speed of the terminal 630. The separate device may include a global positioning system (GPS) module, an acceleration sensor, or a gyroscope sensor. The terminal 630 may determine the mobile level indicating a range corresponding to the measured speed. In other embodiments, the terminal 630 may determine the mobile level for the predicted movement of the terminal 630 based on the user's mobile history information.

[0344] The terminal 630 may determine whether the determined mobility level exceeds a threshold. The threshold may indicate a mobility level at which a weighted value of the robustness degree of the desired cell and a weighted value of the data rate of the desired cell are equal to each other. The terminal 630 may set a weighted value of the robustness degree of the cell and a weighted value of the data rate of the cell differently according to the mobility level.

[0345] The terminal 630 may determine a weighting factor according to whether the mobile level of the terminal 630 exceeds a threshold value. For example, when the terminal 630 moves with the user 2130, the terminal 630 may determine that the mobile level does not exceed the threshold value. Since the mobile level does not exceed the threshold value, the terminal 630 may determine that the robustness of the change of the channel state is at a predetermined level or higher. In order to increase the data rate, the terminal 630 may operate in a cell selection mode based on the best received signal. The terminal 630 may determine a weighting factor corresponding to the cell selection mode based on the best received signal. In another example, when the terminal 630 moves by the car 2180, the terminal 630 may determine that the mobile level exceeds the threshold value. Since the mobile level is relatively high, the terminal 630 may operate in a cell selection mode based on path diversity to select a cell that is robust to the change of the channel state. The terminal 630 may determine a weighting factor corresponding to the cell selection mode based on path diversity.

[0346] The terminal 630 may calculate the CRV based on the determined weighting factor. For example, when the terminal 630 moves with the user 2130, the terminal 630 may calculate the CRV with more attention to the data throughput and data rate of the cell rather than the robustness of the cell. The cell 2121 including the path (e.g., path 2151) with the highest priority best received signal value may be selected. In another example, when the terminal 630 moves with the car 2180, the terminal 630 may calculate the CRV with more attention to the robustness of the cell rather than the data output of the cell. The cell 2111 including a plurality of available paths (e.g., paths 2155, 2156, and 2157) with high non-correlation therebetween may be selected.

[0347] A cell may be selected based on the determined CRV. A subject of selecting a cell may vary depending on the state of the terminal 630. Depending on the state of the terminal 630, a cell may be selected by the terminal 630, or may be selected by a serving BS 680 of the terminal 630.

[0348] In some embodiments, when there is no RRC connection, the terminal 630 can select a cell for initial access. The terminal 630 can select a cell corresponding to the maximum CRV among the CRVs for each cell. For example, when a weighting factor of a cell selection mode based on path diversity according to the mobility level of the terminal 630 moving with the user 2130 is set, the terminal 630 can select a cell 2111 having a relatively large PD value. In another example, when a weighting factor of a cell selection mode based on the best received signal according to the mobility level of the terminal 630 moving with the car 2180 is set, the terminal 630 can select a cell 2121 having a relatively large best received signal value.

[0349] In other embodiments, when there is an RRC connection with the terminal 630, the serving BS 680 may select a cell to provide service to the terminal 630. The terminal 630 may be in a state in which one or more serving cells are set. The serving BS 680 may identify the mobility level of the terminal 630. The serving BS 680 may identify the mobility level of the terminal 630 based on a change in a measurement report value of a neighboring cell periodically received from the terminal 630, a quality measurement value of a reference signal between the serving BS 680 and the terminal, or a change in information on interference occurring near a cell boundary. Alternatively, the serving BS 680 may receive the mobility level of the terminal 630 from the terminal 630.

[0350] The serving BS 680 may select a cell based on the identified mobility level of the terminal 630. For example, when the measurement report values ​​of the neighboring cells of the terminal 630 hardly change, the serving BS 680 may select a cell by assigning a larger weight value to the best received signal value than the PD value.

[0351] The serving BS 680 may select a desired cell according to various schemes. For example, when the serving BS 680 acquires the PD value of the serving cell, for the terminal 630 moving by the car 2180, the serving BS 680 may select a cell 2111 having a large PD value among the serving cells. In another example, when adding a serving cell, for the terminal 630, the serving BS 680 may provide a weighting factor corresponding to a cell selection mode based on path diversity to the terminal 630. The terminal 630 may calculate the CRV of the neighboring cell according to the weighting factor. The terminal 630 may report the CRV to the serving BS 680. The serving BS 680 may select the cell 2111. The serving BS 680 may provide a service to the terminal 630 moving with the car 2180 through the selected cell 2111.

[0352] In the above description, as an example, the terminal 630 moves to another area. However, it goes without saying that the present disclosure is applicable to movement with a change in direction (e.g., the terminal is tilted or rotated). For example, when the rotation speed of the terminal 630 exceeds a threshold, the terminal 630 may determine a weighting factor corresponding to a cell selection mode based on path diversity.

[0353] Fig. 22 is a flowchart showing the operation of a terminal for cell selection based on terminal movement according to an embodiment of the present disclosure. The terminal may be Figure 6 Terminal 630.

[0354] refer to Fig. 22 , will be based on Fig. 20 The operation of the terminal 630 is described on the assumption of the wireless communication environment 1900 or the wireless communication environment 1950.

[0355] refer to Fig. 22 In operation 2210, the terminal 630 may measure a mobility level of the terminal 630. The terminal 630 may measure the mobility level of the terminal 630 based on at least one of the number of handovers, the number of cell additions / releases, the Doppler shift value, and a change in a periodic measurement report value.

[0356] In operation 2220, the terminal 630 may determine whether the measured movement level exceeds a threshold value. When the movement level exceeds the threshold value, the terminal 630 may perform operation 2230. When the movement level does not exceed the threshold value, the terminal 630 may perform operation 2240.

[0357] In operation 2230, the terminal 630 may determine a weighting factor for a cell selection mode based on path diversity. When the terminal 630 moves relatively quickly (e.g., moves with the car 2180), the channel change becomes serious, so a robust link may need to be provided. In the calculation of CRV, the terminal 630 may set a weighting factor so that a larger weighting value is applied to the PD value than the weighting value to be applied to the best received signal value. For example, the weighting factor may be less than 0.5.

[0358] In operation 2240, the terminal 630 may determine a weighting factor of a cell selection mode based on the best received signal.

[0359] When the terminal 630 moves relatively slowly (for example, moves together with the user 2130), the channel change is relatively small, so the robustness at a predetermined level or higher is guaranteed. Therefore, in the calculation of CRV, for the expected data rate, the terminal 630 can set a weighting factor so that a larger weighting value than the weighting value to be applied to the PD value is applied to the best received signal value. For example, the weighting factor can be greater than 0.5.

[0360] In operation 2250, the terminal 630 may determine the CRV. The terminal 630 may determine the CRV of the neighboring cell according to the determined weighting factor. For example, the terminal 630 may calculate the CRV based on the above equation 6. Fig. 20 , but the terminal 630 may perform an access procedure by reporting the determined CRV to the serving BS 680 or selecting a cell having a maximum value among the determined CRVs.

[0361] although Fig.21 and Fig. 22 Only two cell selection modes according to thresholds are described, and the present disclosure is not limited thereto. Three or more separate operation modes may be considered.

[0362] When there is no RRC connection, the terminal 630 can calculate the CRV based on the weighting factor corresponding to the mobile level without determining whether the mobile level exceeds the threshold. A mobile level table can be used. The mobile level table may include three or more mobile levels and weighting factors corresponding to the multiple mobile levels. After detecting the moving speed of the terminal 630, the terminal 630 can identify the corresponding mobile level and determine the corresponding weighting factor to determine the CRV of the neighboring cell.

[0363] Embedded functions may also be used. The terminal 630 may calculate a weighting factor by a function embedded in the detected moving speed. The terminal 630 may determine the CRV of the neighboring cell based on the calculated weighting factor. The terminal 630 may perform an access procedure on the cell having the maximum value in the CRV.

[0364] When there is an RRC connection in the terminal 630, the serving BS 680 may detect the moving speed of the terminal 630 and determine the moving level in the same manner as the determination of the terminal 630. The serving BS 680 may select a cell based on a weighting factor determined according to the moving level. For example, the serving BS 680 may recalculate the CRV of the reported serving cell according to the previous weighting factor. In another example, the serving BS 680 may send measurement configuration information to the terminal 630 to perform measurement for cell addition by the determined weighting factor.

[0365] Various wireless environments depending on a device to which the terminal 630 is connected and the type of the terminal 630 can be conceived.

[0366] In some embodiments, the terminal 630 may be a device that is connected to a display unit (e.g., a monitor or TV) of a vehicle (e.g., a bus, a train, or an airplane) to provide a service. The display unit may be a device that is operably connected to a communication module (e.g., a communication module based on beamforming) of the terminal 630. The display unit may provide an image or video (e.g., an advertisement). The cell may be adaptively selected according to the movement of the vehicle. For example, when the movement of the vehicle is greater than or equal to a threshold, the terminal 630 may operate in a cell selection mode based on path diversity. This is because it is difficult for the user to accurately identify the content of the display unit when the terminal 630 is moving rapidly, so that seamless service of low-quality images (e.g., two-dimensional (2D) images or 16-bit high-color images) is more important than high-quality images (e.g., three-dimensional (3D) images or 32-bit or 24-bit true color images). On the contrary, when the movement of the vehicle is less than a threshold, for example, when the vehicle stops, the terminal 630 may operate in a cell selection mode based on the best received signal. This is because the attention of the calling user may be important when the terminal 630 is stopped. When the terminal 630 accesses a cell with a fast data rate, the display unit can provide a high-quality image.

[0367] In other embodiments, the terminal 630 may be a device connected to an image acquisition device (e.g., a camera, a camcorder, or a closed-circuit TV (CCTV)) to provide a service. The image acquisition device may be a device operatively connected to a communication module of the terminal 630. The image acquisition device may acquire an image or video including a predetermined object. The cell may be adaptively selected according to the capability of the image acquisition device. For example, in cell selection, the terminal 630 may adaptively apply a weighted value according to a QOS requirement (e.g., quarter full high definition (qHD), high definition (HD), quad HD (quad HD, QHD), full high definition (FHD), or ultra high definition (UHD)). The terminal 630 may select a cell with a greater optimal received signal value when the camera requires a large amount of data (e.g., UHD) rather than when the camera requires a small amount of data (e.g., HD). In another example, the terminal 630 may adaptively control the operation mode according to the purpose of the image acquisition device. When high security is required (e.g., for CCTV, black box, or surveillance camera), provision of seamless service is requested, so the terminal 630 can operate in the cell selection mode based on path diversity. On the contrary, when security is relatively less important (e.g., camera for broadcasting), provision of high quality service may be more important, so the terminal 630 can operate in the cell selection mode based on the best received signal.

[0368] In other embodiments, the terminal 630 may be a device connected to a vehicle and an image acquisition device. For example, the terminal 630 may be an unmanned aerial vehicle (UAV). The UAV may also be referred to as a drone. The terminal 630 may adaptively select a cell based on the movement of the vehicle and the configuration of the image acquisition device. For example, Fig.23 The operational scenarios shown in may be considered as examples.

[0369] Fig.23 An example of the operation of UAV 2330 according to an embodiment of the present disclosure is shown.

[0370] refer to Fig.23 , when the UAV 2330 moves at high speed to monitor a wide area, a BS 2310 supporting a cell with a large PD value may be selected to provide seamless service. In this case, when the data rate becomes equal to or less than a threshold, the UAV 2330 may set the quality of the image acquisition device to low. The UAV 2330 may acquire a low-quality image of a predetermined object through a low-quality configuration. The UAV 2330 may send the acquired image to another user, another terminal, or a server. The UAV 2330 may seamlessly provide a predetermined level or higher level of service through a low-quality configuration.

[0371] UAV 2330 can detect a specific object. UAV 2330 can acquire a low-quality image 2360 of the specific object. UAV 2330 can determine that the specific object is an object that needs to be inspected based on the low-quality image 2360. UAV 2330 can stop to accurately identify the specific object. UAV 2330 can change the operation mode from the cell selection mode based on path diversity to the cell selection mode based on the best received signal. In the cell selection mode based on the best received signal, a cell 2320 that can increase the data rate can be selected. Since UAV 2330 can acquire high-quality images, UAV 2330 can set the image acquisition device to high. With the high-quality configuration, UAV 2330 can acquire an image 2370 of the specific object. UAV 2330 can send the acquired image 2370 to another user, another terminal or a server. Thereafter, UAV 2330 can repeat the operation after changing the operation mode back to the cell selection mode based on path diversity so as to monitor the wide area again.

[0372] In addition to the various embodiments described above, various scenarios can be considered. The terminal 630 can adaptively change the operation mode according to the service required in the corresponding operation. When the seamless service provided by the terminal 630 is important (for example, for disaster broadcasting, rescue broadcasting, or traffic information), the terminal 630 can operate in a cell selection mode based on path diversity. A cell with a high PD value can be selected. On the contrary, when the seamlessness of the service of the terminal 630 is relatively less important or the quality of service is important (for example, for advertising, smart metering, or home automation), the terminal 630 can operate in a cell selection mode based on the best received signal. A cell with a large best received signal value can be selected.

[0373] According to various embodiments of the present disclosure, the terminal can perform communication through the target cell by calculating the CRV in consideration of the PD and the best received signal value (e.g., RSRP). The PD value and the best received signal value can be adaptively controlled according to various conditions, and the value representing the cell can be defined differently. The index indicating the cell can be set according to the type of service provided to the terminal, the communication technology supported by the terminal (e.g., LTE-CA or DC), the application used by the terminal (e.g., voice communication application), the mobility level of the terminal, QOS requirements, bandwidth requests, and the importance level of the data to be transmitted. Different BSs, different beams, or different frequencies can be selected according to the set index. For example, when there are obstacles or when the terminal moves, the terminal can prevent unnecessary switching or transmission blocking due to RLF by selecting a cell that is robust to channel changes.

[0374] The methods stated in the claims and / or the specification according to various embodiments may be implemented by hardware, software, or a combination of hardware and software.

[0375] When the method is implemented by software, a computer-readable storage medium for storing one or more programs (software modules) may be provided. One or more programs stored in the computer-readable storage medium may be configured to be run by one or more processors in an electronic device. At least one program may include instructions that cause an electronic device to perform a method according to various embodiments of the present disclosure as defined by the appended claims and / or disclosed herein.

[0376] Programs (software modules or software) can be stored in non-volatile memories, including random access memory (RAM) and flash memory, read-only memory (ROM), electrically erasable programmable ROM (EEPROM), magnetic disk storage devices, compact disk-ROM (CD-ROM), digital versatile disk (DVD) or other types of optical storage devices or tape cassettes. Alternatively, any combination of some or all of them can form a memory storing the program. In addition, a plurality of such memories can be included in the electronic device.

[0377] In addition, the program can be stored in an attachable storage device that can access the electronic device through a communication network such as the Internet, an intranet, a local area network (LAN), a wide LAN (WLAN), and a storage area network (SAN) or a combination thereof. Such a storage device can access the electronic device executing various embodiments of the present disclosure via an external port. In addition, a separate storage device on a communication network can access a portable electronic device.

[0378] In the above-mentioned detailed various embodiments of the present disclosure, according to the detailed embodiments presented, the components included in the present disclosure are expressed in the singular or plural. However, the singular form or plural form is selected for ease of description, suitable for the presented situation, and the various embodiments of the present disclosure are not limited to its single element or multiple elements. In addition, multiple elements described in the description can be configured into a single element, or a single element in the description can be configured into multiple elements.

[0379] While the disclosure has been shown and described with reference to various embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made without departing from the spirit and scope of the disclosure as defined by the appended claims and their equivalents.

Claims

1. A method performed by a user equipment UE in a wireless communication system, the method comprising: receiving a measurement configuration for one or more cells from a base station; receiving one or more downlink signals associated with one or more beams on a cell; Obtaining a measurement result of the cell based on the measurement configuration; as well as Send the cell measurement results to the base station, The measurement results of the cell include: the result of layer 3 filtering of the cell quality of the cell, and information about a number of one or more available beams, each of the one or more available beams providing a signal quality above a threshold, The cell quality is obtained based on an average of signal qualities of downlink signals among the one or more downlink signals, and Wherein, each of the signal qualities is above the threshold.

2. The method of claim 1, wherein: The signal quality corresponds to at least one of a reference signal received power RSRP, a reference signal received quality RSRQ, and a signal to interference and noise ratio SINR, and The threshold is configured for the cell to be measured.

3. The method of claim 1, wherein: The measurement configuration also includes information based on the frequency information of the cell and the beam information of the cell.

4. The method of claim 1, wherein: The measurement results of the cell are obtained including: obtaining one or more measurement values ​​by measuring the one or more downlink signals; and performing layer 1 filtering on the one or more measurements to obtain a signal quality of a downlink signal, Here, an averaging operation is performed between layer 1 filtering and layer 3 filtering.

5. The method of claim 1, wherein: Sending measurement results includes: Determining whether a reporting condition in a measurement configuration is met based on a result of the layer 3 filtering; and When the reporting condition is met, the measurement result is sent to the base station.

6. The method of claim 1, wherein: The signal quality includes power values ​​of a plurality of beams associated with the downlink signal.

7. The method of claim 1, wherein: The one or more downlink signals include one or more channel state information reference signals CSI-RS.

8. The method of claim 1, wherein: The result of layer 3 filtering is obtained based on the following equation: F n =(1-a)·F n-1 +a·M n Among them, F n represents the result of layer 3 filtering, F n-1 represents the previous measurement result of layer 3 filtering, M n represents the most recently received measurement result from layer 1, and 'a' represents the filter coefficient.

9. A method performed by a base station in a wireless communication system, the method comprising: Sending a measurement configuration for one or more cells to a user equipment UE; as well as receiving measurement results of the cell based on the measurement configuration from the UE, The measurement results of the cell include: the result of layer 3 filtering of the cell quality of the cell, and information about a number of one or more available beams, each of the one or more available beams providing a signal quality above a threshold, wherein the cell quality corresponds to an average of signal qualities of downlink signals in one or more downlink signals associated with one or more beams on the cell, and Wherein, each of the signal qualities is above the threshold.

10. The method of claim 9, wherein: The threshold is configured for the cell to be measured.

11. A user equipment UE in a wireless communication system, the UE comprising: at least one transceiver; as well as at least one processor operably coupled to the at least one transceiver, the at least one processor configured to: controlling the at least one transceiver to receive a measurement configuration for one or more cells from a base station; controlling the at least one transceiver to receive one or more downlink signals associated with one or more beams on a cell; Obtaining a measurement result of the cell based on the measurement configuration; as well as controlling the at least one transceiver to send a measurement result of the cell to a base station, The measurement results of the cell include: The results of layer 3 filtering of the cell quality for the cell, and information about a number of one or more available beams, each of the one or more available beams providing a signal quality above a threshold, The cell quality is obtained based on an average of signal qualities of downlink signals among the one or more downlink signals, and Wherein, each of the signal qualities is above the threshold.

12. The UE according to claim 11, wherein: The signal quality corresponds to at least one of a reference signal received power RSRP, a reference signal received quality RSRQ, and a signal to interference and noise ratio SINR, and The threshold is configured for the cell to be measured.

13. The UE according to claim 11, wherein: The measurement configuration also includes information based on the frequency information of the cell and the beam information of the cell.

14. The UE according to claim 11, wherein: In order to obtain a measurement result of a cell, the at least one processor is configured to: obtaining one or more measurement values ​​by measuring the one or more downlink signals; and performing layer 1 filtering on the one or more measurements to obtain signal quality, Here, an averaging operation is performed between layer 1 filtering and layer 3 filtering.

15. The UE according to claim 11, wherein: To send the measurement report, the at least one processor is configured to: Determining whether a reporting condition in a measurement configuration is met based on a result of layer 3 filtering; as well as When the reporting condition is met, the at least one transceiver is controlled to send the measurement result.

16. The UE according to claim 11, wherein: The signal quality includes power values ​​of a plurality of beams associated with the downlink signal.

17. The UE according to claim 11, wherein: The downlink signal includes one or more channel state information reference signals CSI-RS.

18. The UE according to claim 11, wherein: The result of layer 3 filtering is obtained based on the following equation: F n =(1-a)·F n-1 +a·M n ,as well as Among them, F n represents the result of layer 3 filtering, F n-1 represents the previous measurement result of layer 3 filtering, M n represents the most recently received measurement result from layer 1, and 'a' represents the filter coefficient.

19. A device of a base station in a wireless communication system, comprising: at least one transceiver; as well as at least one processor operably coupled to the at least one transceiver, the at least one processor configured to: Controlling the at least one transceiver to send a measurement configuration for one or more cells to a user equipment UE; as well as controlling the at least one transceiver to receive, from the UE, a measurement result of a cell based on the measurement configuration, The cell measurement results include: The results of layer 3 filtering of the cell quality for the cell, and information about a number of one or more available beams, each of the one or more available beams providing a signal quality above a threshold, wherein the cell quality corresponds to an average of signal qualities of downlink signals in one or more downlink signals associated with one or more beams on the cell, and Wherein, each of the signal qualities is above the threshold.

20. The device of claim 19, wherein: The threshold is configured for the cell to be measured.

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