Discovery signal-based measurement method and device in wireless communication system

Abstract

The present disclosure relates to a 5G or 6G communication system for supporting a higher data transmission rate. The present disclosure proposes a method by which a terminal performs discovery signal-based measurement. A method performed by a terminal in a wireless communication system, according to one embodiment of the present disclosure, comprises the steps of: identifying whether at least one characteristic of a cell discovery signal transmitted from a base station exceeds a threshold value; determining that cell discovery is successful if the at least one characteristic exceeds the threshold value; and transmitting, to the base station, a request signal for requesting transmission of an on-demand synchronization signal block (SSB), on the basis of the determination, wherein the base station is in a power saving state.

Description

Discovery signal-based measurement method and device for a wireless communication system

[0001] The present disclosure relates to a communication method of a wireless communication system, and more specifically to a method and apparatus for defining efficient frequency usage and transmission and reception operations of a terminal.

[0002] 5G mobile communication technology defines a wide frequency band to enable fast transmission speeds and new services, and can be implemented not only in frequency bands below 6 GHz ('Sub 6 GHz'), such as 3.5 gigahertz (3.5 GHz), but also in ultra-high frequency bands known as millimeter wave (mmWave), such as 28 GHz and 39 GHz ('Above 6 GHz'). In addition, for 6G mobile communication technology, which is referred to as a system beyond 5G, measures are being considered to achieve even faster transmission speeds and even lower ultra-low latency compared to 5G mobile communication technology.

[0003] In the early stages of 5G mobile communication technology, aiming to satisfy service support and performance requirements for enhanced Mobile BroadBand (eMBB), Ultra-Reliable Low-Latency Communications (URLLC), and massive Machine-Type Communications (mMTC), technologies such as beamforming and Massive MIMO to mitigate path loss and increase transmission distance in ultra-high frequency bands, support for various numerologies (such as operating multiple subcarrier spacings) and dynamic operation of slot formats for the efficient utilization of ultra-high frequency resources, initial access techniques to support multi-beam transmission and broadband, definition and operation of Band-Width Parts (BWP), Low Density Parity Check (LDPC) codes for high-volume data transmission, new channel coding methods such as Polar Codes for reliable transmission of control information, and L2 pre-processing (L2 Standardization has been carried out for pre-processing, network slicing which provides a dedicated network specialized for specific services, and other methods.

[0004] In addition, discussions are underway to improve and enhance the performance of the initial 5G mobile communication technology in consideration of the services that the 5G mobile communication technology was intended to support. Standardization has been carried out for technologies such as V2X (Vehicle-to-Everything), which helps autonomous vehicles make driving decisions and enhance user convenience based on their own location and status information transmitted by the vehicle; NR-U (New Radio Unlicensed), which aims for system operation in unlicensed bands to comply with various regulatory requirements; NR terminal low power consumption technology (UE Power Saving); Non-Terrestrial Network (NTN), which is direct terminal-satellite communication for securing coverage in areas where communication with the terrestrial network is impossible; and positioning.

[0005] In addition, standardization was also carried out for technologies such as the Industrial Internet of Things (IIoT) to support new services through linkage and convergence with other industries, Integrated Access and Backhaul (IAB) which provides nodes to expand network service areas by integrating wireless backhaul links and access links, Mobility Enhancement including Conditional Handover and Dual Active Protocol Stack (DAPS) Handover, and 2-step RACH for NR which simplifies random access procedures.

[0006] In addition, standardization is underway for 5G baseline architectures (e.g., Service based Architecture, Service based Interface) for the integration of Network Functions Virtualization (NFV) and Software-Defined Networking (SDN) technologies, as well as for Mobile Edge Computing (MEC), which provides services based on the location of the terminal.

[0007] With the commercialization of such 5G mobile communication systems, connected devices, which are increasing explosively, will be connected to communication networks. Accordingly, it is expected that there will be a need to enhance the functionality and performance of 5G mobile communication systems and to integrate the operation of connected devices. To this end, new research is planned to be conducted on 5G performance improvement and complexity reduction, support for AI services, support for metaverse services, and drone communication using eXtended Reality (XR), Artificial Intelligence (AI), and Machine Learning (ML) to efficiently support Augmented Reality (AR), Virtual Reality (VR), and Mixed Reality (MR).

[0008] In addition, the advancement of these 5G mobile communication systems can serve as a foundation for the development of new waveforms for ensuring coverage of 6G mobile communication technology, multi-antenna transmission technologies such as Full Dimensional MIMO (FD-MIMO), array antennas, and large-scale antennas, metamaterial-based lenses and antennas, high-dimensional spatial multiplexing technology using Orbital Angular Momentum (OAM), and Reconfigurable Intelligent Surface (RIS) technology, as well as Full Duplex technology for improving frequency efficiency and system networks of 6G mobile communication technology, AI-based communication technology that realizes system optimization by utilizing satellites and AI from the design stage and internalizing end-to-end AI support functions, and next-generation distributed computing technology that realizes services of complexity exceeding the limits of terminal computing capabilities by utilizing ultra-high-performance communication and computing resources.

[0009] The disclosed embodiments aim to provide an apparatus and method capable of effectively providing mobile communication services. Specifically, they provide a procedure for energy saving of a base station and a terminal.

[0010] The technical problems to be solved in the disclosed embodiments are not limited to those mentioned above, and other technical problems not mentioned may be considered by those skilled in the art from the various embodiments of the present disclosure described below.

[0011] The present disclosure relates to a method for processing control signals performed by a terminal in a wireless communication system, comprising: receiving a determination of whether at least one characteristic of a first control cell discovery signal transmitted from a base station exceeds a threshold value; determining that cell discovery is successful if the at least one characteristic exceeds the threshold value; and transmitting a request signal requesting the transmission of an on-demand synchronization signal block (SSB) to the base station based on the determination, wherein the base station is in a power saving state.

[0012] The present disclosure relates to a terminal in a wireless communication system, wherein the terminal comprises a transceiver; and at least one processor; wherein the at least one processor identifies whether at least one characteristic of a cell discovery signal transmitted from a base station exceeds a threshold value, and if the at least one characteristic exceeds the threshold value, determines that cell discovery has been successful, and, based on the determination, transmits a request signal requesting the transmission of an on-demand synchronization signal block (SSB) to the base station, and wherein the base station is in a power saving state.

[0013] The various embodiments of the present disclosure described above are merely some of the preferred embodiments of the present disclosure, and various embodiments reflecting the technical features of the various embodiments of the present disclosure can be derived and understood by those skilled in the art based on the detailed description to be described below.

[0014] Embodiments of the present disclosure provide a transceiver device and method for a terminal and a base station that improve frequency usage efficiency in a mobile communication system. Specifically, according to at least one embodiment of the present disclosure, the base station and the terminal can effectively perform an initial connection procedure for energy saving between the base station and the terminal.

[0015] The effects obtainable from the disclosed embodiments are not limited to those mentioned above, and other unmentioned effects can be clearly derived and understood by a person skilled in the art based on the following detailed description.

[0016] FIG. 1 is a diagram showing the basic structure of the time-frequency resource domain of a 5G system according to one embodiment of the present disclosure.

[0017] FIG. 2 is a diagram illustrating a random access procedure according to one embodiment of the present disclosure.

[0018] FIG. 3 is a diagram illustrating a procedure in which a terminal reports terminal capability (UE capability) information to a base station according to one embodiment of the present disclosure.

[0019] FIG. 4 is a drawing showing an example of a bandwidth portion setting according to one embodiment of the present disclosure.

[0020] FIG. 5 is a diagram showing the interrelationship between frequency bands and coverage according to one embodiment of the present disclosure.

[0021] FIG. 6 is a diagram showing an example of a base station energy saving method according to one embodiment of the present disclosure.

[0022] FIG. 7 is a diagram showing an example of a base station energy saving method according to one embodiment of the present disclosure.

[0023] FIG. 8 is a diagram showing an example of a base station energy saving method according to one embodiment of the present disclosure.

[0024] FIG. 9 is a diagram showing an example of a base station energy saving method according to one embodiment of the present disclosure.

[0025] FIG. 10 is a diagram illustrating a cell discovery method of a terminal according to one embodiment of the present disclosure.

[0026] FIG. 11 is a diagram illustrating an initial connection procedure of a terminal according to one embodiment of the present disclosure.

[0027] FIG. 12 is a diagram illustrating a terminal measurement method according to one embodiment of the present disclosure.

[0028] FIG. 13 is a diagram showing the operation of a terminal and a base station for an initial connection procedure of a terminal according to one embodiment of the present disclosure.

[0029] FIG. 14 is a diagram showing an example of terminal operation during a terminal initial connection procedure according to one embodiment of the present disclosure.

[0030] FIG. 15 is a diagram showing an example of base station operation to support a terminal initial connection procedure according to one embodiment of the present disclosure.

[0031] FIG. 16 is a drawing showing a terminal transceiver device according to one embodiment of the present disclosure.

[0032] FIG. 17 is a block diagram illustrating the structure of a terminal according to one embodiment of the present disclosure.

[0033] FIG. 18 is a block diagram illustrating the structure of a base station according to one embodiment of the present disclosure.

[0034] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. Furthermore, in describing the present disclosure, if it is determined that a detailed description of related known functions or configurations might unnecessarily obscure the essence of the present disclosure, such detailed description will be omitted. Additionally, the terms described below are defined considering their functions in the present disclosure, and these may vary depending on the intentions or conventions of the user or operator. Therefore, their definitions should be based on the content throughout this specification.

[0035] The advantages and features of the present disclosure and the methods for achieving them will become clear by referring to the embodiments described below in detail together with the accompanying drawings. However, the present disclosure is not limited to the embodiments disclosed below but may be implemented in various different forms. The embodiments provided are merely to make the present disclosure complete and to fully inform those skilled in the art of the scope of the disclosure, and the present disclosure is defined only by the scope of the claims. Throughout the specification, the same reference numerals refer to the same components.

[0036] At this point, it will be understood that each block of the process flow diagrams and combinations of the flow diagrams can be executed by computer program instructions. Since these computer program instructions can be loaded into the processor of a general-purpose computer, a special-purpose computer, or other programmable data processing equipment, the instructions executed through the processor of the computer or other programmable data processing equipment create means to perform the functions described in the flow diagram block(s). Since these computer program instructions can also be stored in computer-available or computer-readable memory that can be directed toward the computer or other programmable data processing equipment to implement the function in a specific way, the instructions stored in computer-available or computer-readable memory can also produce a manufactured item containing instruction means to perform the function described in the flow diagram block(s). Since computer program instructions can be loaded onto a computer or other programmable data processing equipment, instructions that perform a series of operation steps on the computer or other programmable data processing equipment to create a process executed by the computer can also provide steps for executing the functions described in the flowchart block(s).

[0037] Additionally, each block may represent a module, segment, or part of code containing one or more executable instructions for executing a specific logical function(s). It should also be noted that in some alternative execution examples, the functions mentioned in the blocks may occur out of order. For example, two blocks described in succession may actually be executed substantially simultaneously, or the blocks may sometimes be executed in reverse order according to their corresponding functions.

[0038] In this embodiment, the term "part" refers to a software or hardware component such as an FPGA (Field Programmable Gate Array) or an ASIC (Application Specific Integrated Circuit), and the "part" performs certain roles. However, the meaning of "part" is not limited to software or hardware. The "part" may be configured to reside in an addressable storage medium or configured to run one or more processors. Thus, as an example, the "part" includes components such as software components, object-oriented software components, class components, and task components, as well as processes, functions, attributes, procedures, subroutines, segments of program code, drivers, firmware, microcode, circuits, data, databases, data structures, tables, arrays, and variables. The functions provided within the components and "parts" may be combined into a smaller number of components and "parts" or further separated into additional components and "parts." In addition, the components and 'parts' may be implemented to utilize one or more CPUs within the device or secure multimedia card. Also, in the embodiments, 'parts' may include one or more processors.

[0039] In the present disclosure, each of the phrases such as “A or B,” “at least one of A and B,” “at least one of A or B,” “A, B or C,” “at least one of A, B and C,” and “at least one of A, B, or C” may include any one of the items listed together in the corresponding phrase, or all possible combinations thereof. Terms such as “first,” “second,” or “first” or “second” may be used simply to distinguish a corresponding component from another corresponding component and do not limit the components in any other aspect (e.g., importance or order).

[0040] In describing the present disclosure below, specific descriptions of related known functions or configurations will be omitted if it is determined that such detailed descriptions would unnecessarily obscure the essence of the present disclosure. Embodiments of the present disclosure will be described below with reference to the attached drawings.

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

[0042] In the following description, the terms "physical channel" and "physical signal" may be used interchangeably with "data" or "control signal." For example, PDSCH (physical downlink shared channel) is a term referring to a physical channel through which data is transmitted, but PDSCH may also be used to refer to data. That is, in this disclosure, the expression "transmits a physical channel" may be interpreted as equivalent to the expression "transmits data or a signal through a physical channel."

[0043] In the present disclosure, upper layer signaling refers to a signal transmission method transmitted from a base station to a terminal using a physical layer downlink data channel, or from a terminal to a base station using a physical layer uplink data channel. Upper layer signaling can be understood as a Master Information Block (MIB), System Information Block (SIB), Radio Resource Control (RRC) signaling, or Media Access Control (MAC) control element (CE).

[0044] For the convenience of the following description, the present disclosure uses terms and names defined in the 3GPP NR (New Radio: 5th generation mobile communication standard) specifications. However, the present disclosure is not limited to the above terms and names and may be applied equally to systems conforming to other standards. For example, regarding 6G systems, which are still in the early stages of standardization discussion, terms and names defined in 5G systems may be generalized and used to describe the operation of 6G systems unless otherwise specifically noted.

[0045] Hereinafter, the base station is an entity that performs resource allocation for terminals and may be at least one of a gNodeB, gNB, eNodeB, eNB, NodeB, BS (Base Station), wireless access unit, base station controller, or a node on a network. The terminal may include a UE (User Equipment), MS (Mobile Station), cellular phone, smartphone, computer, IoT device, sensor, or multimedia system capable of performing communication functions. Of course, it is not limited to the examples described.

[0046] While existing mobile communication systems focused on conventional voice / data communication, 5G systems aim to satisfy various services and requirements, such as enhanced mobile broadband (eMBB) services to improve existing voice / data communication, ultra-reliable and low latency communication (URLLC) services, and massive machine type communication (MTC) services to support mass communication of the machine.

[0047] While the transmission bandwidth per carrier of existing mobile communication systems, such as LTE (Long Term Evolution or E-UTRA (Evolved Universal Terrestrial Radio Access)) and LTE-A (LTE-Advanced or E-UTRA Evolution), is limited to a maximum of 20 MHz, 5G systems aim to provide ultra-high-speed data services reaching several Gbps by utilizing significantly wider ultra-wide bandwidths. Accordingly, 5G systems are considering ultra-high frequency bands ranging from several GHz to up to 100 GHz as operating frequencies, where securing ultra-wide bandwidth frequencies is relatively easy. Additionally, it is possible to secure wide bandwidth frequencies for 5G systems through frequency reallocation or allocation from frequency bands ranging from hundreds of MHz to several GHz used by existing mobile communication systems.

[0048] Radio waves in the ultra-high frequency band have wavelengths of several millimeters and are also called millimeter waves (mmWave). However, in the ultra-high frequency band, path loss of radio waves increases in proportion to the frequency band, so the coverage of mobile communication systems can be reduced.

[0049] To overcome the disadvantage of reduced coverage in the ultra-high frequency band, beamforming technology can be applied. This technology uses multiple antennas to concentrate radio wave radiated energy toward a specific target point, thereby increasing the reach of the radio waves. In other words, a signal to which beamforming technology is applied has a relatively narrower beam width, and as radiated energy is concentrated within this narrowed beam width, the reach of the radio waves increases. Beamforming technology can be applied to both the transmitting and receiving ends. In addition to the effect of increasing coverage, beamforming technology also has the effect of reducing interference in areas outside the beamforming direction. For beamforming technology to operate properly, accurate measurement and feedback methods for the transmit and receive beams are required. Beamforming technology can be applied to control channels or data channels that correspond one-to-one between a specific terminal and a base station. Furthermore, beamforming technology can be applied to control channels and data channels used to transmit common signals—such as synchronization signals, physical broadcast channels (PBCH), and system information—that a base station transmits to multiple terminals within the system, in order to increase coverage. When applying beamforming technology to a common signal, beam sweeping technology, which changes the beam direction to transmit the signal, is additionally applied to ensure that the common signal reaches terminals located at any position within the cell.

[0050] Another requirement for 5G systems is ultra-low latency services, where the transmission delay between the transmitter and receiver is approximately 1ms. As a measure to reduce transmission delay, it is necessary to design a frame structure based on a short TTI (transmission time interval) that is shorter than that of LTE and LTE-A. TTI is the basic time unit for performing scheduling, and the TTI of existing LTE and LTE-A systems is 1ms, which corresponds to the length of one subframe. For example, in 5G systems, short TTIs such as 0.5ms, 0.25ms, and 0.125ms are possible, which are shorter than those of existing LTE and LTE-A systems, to satisfy the requirements for ultra-low latency services.

[0051] FIG. 1 is a diagram showing the basic structure of the time-frequency resource domain of a 5G system according to one embodiment of the present disclosure.

[0052] That is, Figure 1 is a diagram showing the basic structure of the time-frequency resource area, which is a wireless resource area where data or control channels of a 5G system are transmitted.

[0053] Referring to FIG. 1, the horizontal axis represents the time domain and the vertical axis represents the frequency domain. The minimum transmission unit of a 5G system in the time domain is an OFDM (orthogonal frequency division multiplexing) symbol, A number of symbols (102) are combined to form a slot (106), and A number of slots can be combined to form a single subframe (105). The length of a single subframe (105) is 1.0 ms, and 10 subframes can be combined to form a single 10 ms frame (114), and the length of the frame (114) is 10 ms. The minimum transmission unit in the frequency domain is a subcarrier, and the bandwidth of the entire system transmission bandwidth is a total of NBW It can be composed of several subcarriers (104).

[0054] In the time-frequency domain, the basic unit of a resource is a resource element (RE) (112), which can be represented by an OFDM symbol index and a subcarrier index. A resource block (RB or Physical Resource Block, PRB) is in the frequency domain. It can be defined as a series of consecutive subcarriers (110). In a 5G system = 12, and the data rate can increase in proportion to the number of RBs scheduled to the terminal.

[0055] In a 5G system, base stations map data in RB units and can generally perform scheduling on RBs that constitute a slot for a given terminal. That is, in a 5G system, the basic time unit for which scheduling is performed is a slot, and the basic frequency unit for which scheduling is performed may be an RB.

[0056] OFDM symbol count It is determined by the length of the cyclic prefix (CP) added to each symbol to prevent interference between symbols; for example, if a normal CP is applied = 14, if Extended CP is applied = 12. Extended CP is applied to systems with relatively longer transmission distances than standard CP, enabling the maintenance of orthogonality between symbols. In the case of standard CP, the ratio of CP length to symbol length is maintained at a constant value, allowing the overhead caused by CP to remain constant regardless of the subcarrier spacing. That is, if the subcarrier spacing is small, the symbol length increases, and consequently, the CP length can also increase. Conversely, if the subcarrier spacing is large, the symbol length decreases, and consequently, the CP length can be reduced. The symbol length and CP length can be inversely proportional to the subcarrier spacing.

[0057] In 5G systems, various frame structures can be supported by adjusting the subcarrier spacing to satisfy various services and requirements. For example, the characteristics according to the subcarrier spacing are as follows.

[0058] From the perspective of the operating frequency band, a larger subcarrier spacing is advantageous for recovering phase noise in the high-frequency band.

[0059] - From the perspective of transmission time, a large subcarrier spacing shortens the symbol length in the time domain, and consequently shortens the slot length, which is advantageous for supporting ultra-low latency services such as URLLC.

[0060] - From the perspective of cell size, the longer the CP length, the larger the cell can be supported; therefore, the smaller the subcarrier spacing, the larger the cell can be supported. A cell is a concept in mobile communication that refers to the area covered by a single base station.

[0061] Subcarrier spacing and CP length are essential information for OFDM transmission and reception; therefore, smooth transmission and reception are possible only when the base station and the terminal recognize these values ​​as common. [Table 1] shows the subcarrier spacing configuration (μ) and subcarrier spacing ( It shows an example of the relationship between ), CP lengths.

[0062] [Table 1]

[0063]

[0064] Table 2 shows the subcarrier spacing settings for the standard CP ( ) Stars, number of symbols per slot ( ), number of slots per frame ( ), and number of slots per subframe ( Represents an example of ).

[0065] [Table 2]

[0066]

[0067] Table 3 shows the subcarrier spacing settings for the extended CP ( ) Stars, number of symbols per slot ( ), number of slots per frame ( ), and number of slots per subframe ( Represents an example of ).

[0068] [Table 3]

[0069]

[0070] A 5G system can satisfy various user requirements through coexistence or dual-mode operation with existing LTE or / and LTE-A (hereinafter LTE / LTE-A) systems. For example, the existing LTE / LTE-A system can provide stable system operation to the terminal, and the 5G system can perform the role of providing enhanced services to the terminal. Therefore, the frame structure of the 5G system needs to include at least the frame structure of LTE / LTE-A or a set of essential parameters (subcarrier spacing = 15 kHz).

[0071] For example, when comparing a frame structure with a subcarrier spacing setting μ=0 (hereinafter frame structure A) and a frame structure with a subcarrier spacing setting μ=1 (hereinafter frame structure B), compared to frame structure A, frame structure B shows that the subcarrier spacing and RB size are doubled, while the slot length and symbol length are doubled. In the case of frame structure B, 2 slots can form one subframe, and 20 subframes can form one frame.

[0072] By generalizing the frame structure of a 5G system, high scalability can be provided by ensuring that essential parameter sets, such as subcarrier spacing, CP length, and slot length, have an integer multiple relationship with each other for each frame structure. Additionally, a subframe of fixed length of 1ms can be defined to represent a reference time unit independent of the frame structure.

[0073] The frame structure of a 5G system can be applied to various scenarios. From the perspective of cell size, since a longer CP length enables support for larger cells, Frame Structure A can support relatively larger cells compared to Frame Structure B. From the perspective of operating frequency band, since a larger subcarrier spacing is advantageous for recovering phase noise in the high-frequency band, Frame Structure B can support relatively higher operating frequencies compared to Frame Structure A. From the perspective of service, since a shorter slot length—the basic time unit of scheduling—is advantageous for supporting ultra-low latency services such as URLLC, Frame Structure B may be relatively more suitable for URLLC services compared to Frame Structure A.

[0074] In a manner similar to the coexistence of 5G and LTE / LTE-A mentioned above, it may be necessary to design a system for the coexistence of 6G, which will arrive with the evolution of future communication systems, and existing systems such as 5G or LTE / LTE-A.

[0075] In the following description of the present disclosure, an uplink (UL) refers to a wireless link through which a terminal transmits data or control signals to a base station, and a downlink (DL) may refer to a wireless link through which a base station transmits data or control signals to a terminal.

[0076] In the initial access phase, when the terminal first connects to the system, the terminal can synchronize downlink time and frequency from the synchronization signal (SS) transmitted by the base station through cell search and obtain a cell identifier (cell ID). Then, the terminal can receive a physical broadcast channel (PBCH) using the obtained cell ID and obtain a master information block (MIB), which is essential system information, from the PBCH. The MIB may include at least one of the following information.

[0077] MIB ::= SEQUENCE {

[0078] systemFrameNumber BIT STRING (SIZE (6));

[0079] subCarrierSpacingCommon ENUMERATED {scs15or60, scs30or120},

[0080] ssb-SubcarrierOffset INTEGER (0..15);

[0081] dmrs-TypeA-Position ENUMERATED {pos2, pos3},

[0082] pdcch-ConfigSIB1 PDCCH-ConfigSIB1,

[0083] cellBarred ENUMERATED {barred, notBarred},

[0084] intraFreqReselection ENUMERATED {allowed, notAllowed},

[0085] spare BIT STRING (SIZE (1))

[0086] }

[0087] For example, the above essential system information may include at least one of the following: information regarding the location of a synchronization signal received by the terminal in the time domain and / or frequency domain; control information for the terminal to receive at least one of system information (or system information block, SIB) transmitted by the base station (which may be information for scheduling a data channel for receiving system information); information regarding whether the cell is connectable; and information regarding the SCS of the cell. The above essential system information may be referred to as system information.

[0088] Additionally, the terminal can receive system information transmitted by the base station to obtain cell-common transmission and reception control information. Cell-common transmission and reception control information may include random access control information, paging control information, and at least one of common control information for various physical channels and signals (at least one of channels and signals, such as an uplink control channel, an uplink data channel, a downlink control channel and a downlink data channel, a physical signal for obtaining uplink channel status information, a physical signal for obtaining downlink channel status information, and a physical signal for demodulating a physical channel). The control information may be configuration information for each channel or signal. The system information may be referred to, for example, as SIB1 or RMSI (remaining minimum system information).

[0089] The synchronization signal is a signal that serves as a reference for cell search, and a subcarrier spacing may be applied for each frequency band to suit channel environments such as phase noise. In the case of data channels or control channels, as described above, the subcarrier spacing may be applied differently depending on the service type to support various services. In a 5G system, a combination consisting of PSS (primary synchronization signal), SSS (secondary synchronization signal), and PBCH (Physical broadcast channel) can be referred to as an SS / PBCH block or SSB. For example, an SSB may consist of N1 PSS symbols, N2 SSS symbols, and N3 PBCH symbols.

[0090] In addition to the above initial connection procedure, the terminal may also receive an SSB to determine whether the radio link quality of the current cell is maintained at a certain level or higher. Additionally, in the procedure where the terminal performs a handover from the current cell to an adjacent cell, the terminal may receive an SSB from an adjacent cell to determine the radio link quality of the adjacent cell and to obtain time / frequency synchronization of the adjacent cell.

[0091] After the terminal obtains MIB and system information from the base station through the initial access procedure, the terminal may perform a random access procedure to transition the link with the base station to a connected state (connected state or RRC_CONNECTED state). Upon completion of the random access procedure, the terminal transitions to a connected state, enabling one-to-one communication between the base station and the terminal. The random access procedure will be described in detail below with reference to FIG. 2.

[0092] FIG. 2 is a diagram illustrating a random access procedure according to one embodiment of the present disclosure.

[0093] Referring to FIG. 2, as a first step (210) of the random access procedure, the terminal can transmit a random access preamble to the base station. The random access preamble, which is the initial transmission message of the terminal in the random access procedure, may be referred to as message 1. The base station can measure the transmission delay value between the terminal and the base station from the random access preamble and synchronize the uplink. At this time, the terminal can arbitrarily select which random access preamble to use from a set of random access preambles given in advance by system information. The initial transmission power of the random access preamble can be determined according to the path loss between the base station and the terminal measured by the terminal. Additionally, the terminal can determine the transmission beam direction of the random access preamble from the synchronization signal received from the base station and transmit the random access preamble.

[0094] In the second step (220), the base station may transmit a message to the terminal containing an uplink transmission timing control command based on the transmission delay value measured from the random access preamble received in the first step (210). The terminal may receive control information for scheduling the message over the downlink control channel and receive the message over the downlink data channel based on the control information. The message transmitted in the second step may be referred to as message 2, a response to the random access preamble, or a random access response. Additionally, the base station may transmit the message by including, as scheduling information, uplink resources to be used by the terminal to transmit a response message (message 3) to message 2 and power control commands to be applied to the response message. The scheduling information may include control information regarding the terminal's uplink transmission beam. Additionally, the message may further include a temporary identifier of the terminal to be used during the random access procedure. The information included in the message is merely an example, and one or more of the information described above may be included in message 2.

[0095] If the terminal does not receive message 2, which is scheduling information for message 3, from the base station within a predetermined time in the second step (220), the terminal may perform the first step (210) again. If the first step (210) is performed again, the terminal may increase the probability of receiving the random access preamble at the base station by increasing the transmission power of the random access preamble by a predetermined step (power ramping).

[0096] In the third step (230), the terminal can transmit uplink data (message 3) including its terminal ID to the base station via the uplink data channel (physical uplink shared channel, PUSCH) based on the uplink resources allocated in the second step (220). The transmission timing of the uplink data channel for transmitting Message 3 may follow the uplink transmission timing control command received from the base station in the second step (220). The transmission power of the uplink data channel for transmitting Message 3 may be determined by considering the power control command received from the base station in the second step (220) and the power ramping value of the random access preamble. The uplink data channel for transmitting Message 3 may refer to the first uplink data signal transmitted by the terminal to the base station after the transmission of the random access preamble. For example, the message 3 may include an upper layer message for the terminal to connect to the network.

[0097] In step 4 (240), if the base station determines that the terminal has performed random access without collision with other terminals, it may transmit data (message 4) containing the ID of the terminal that transmitted uplink data in step 3 (230) to the terminal. If the terminal receives the signal transmitted by the base station in step 4 (240) from the base station, it may determine that the random access was successful. Then, the terminal may transmit HARQ-ACK information indicating successful reception of message 4 to the base station through the Physical Uplink Control Channel (PUCCH).

[0098] If the data transmitted by the terminal in the third step (230) collides with the data of another terminal and the base station fails to receive the data signal from the terminal, the base station may not transmit any further data to the terminal. Accordingly, if the terminal fails to receive the data transmitted from the base station in the fourth step (240) within a certain period of time, it is determined that the random access procedure has failed, and the process may be restarted from the first step (210).

[0099] The four-step random access procedure described above is merely an example, and the information between the terminal and the base station described above may also be transmitted through messages other than the four-step message described above. For example, the terminal may transmit one or more messages containing at least one of the information of message 1 and message 3 to the base station simultaneously or sequentially, and the base station may transmit one or more messages containing at least one of the information of message 2 and message 4 to the terminal simultaneously or sequentially.

[0100] Upon successful completion of the random access procedure, the terminal transitions to a connected state, enabling one-to-one communication between the base station and the terminal. The base station can receive UE capability information from the terminal in the connected state. The base station can adjust scheduling by referring to the UE capability information of the terminal. Through the UE capability information, the terminal can inform the base station whether it supports certain functions and / or the maximum allowable value of the functions supported by the terminal. Therefore, the UE capability information reported by each terminal to the base station may be different for each terminal.

[0101] For example, the terminal may report UE capability information to the base station as UE capability information, including at least a portion of the following control information.

[0102] - Control information related to the frequency bands supported by the terminal

[0103] - Control information related to channel bandwidth supported by the terminal

[0104] - Control information regarding the maximum modulation scheme supported by the terminal

[0105] - Control information regarding the maximum number of beams supported by the terminal

[0106] - Control information regarding the maximum number of layers supported by the terminal

[0107] - Control information related to CSI reporting supported by the terminal

[0108] - Control information on whether the terminal supports frequency hopping

[0109] - Bandwidth-related control information when Carrier Aggregation (CA) is supported

[0110] - Control information on whether cross-carrier scheduling is supported when carrier bundling is supported

[0111] FIG. 3 is a diagram illustrating a procedure in which a terminal reports terminal capability (UE capability) information to a base station according to one embodiment of the present disclosure.

[0112] Referring to FIG. 3, in step 310, the base station (302) can send a UE capability information request message to the terminal (301). In response to the base station's UE capability information request, the terminal can send UE capability information to the base station in step 320.

[0113] Next, the Bandwidth Part (BWP) setting in the 5G communication system will be explained in detail with reference to the drawing.

[0114] FIG. 4 is a drawing showing an example of a bandwidth portion setting according to one embodiment of the present disclosure.

[0115] FIG. 4 shows an example in which the terminal bandwidth (UE bandwidth) (400) is configured into two bandwidth portions, namely bandwidth portion #1 (BWP#1) (401) and bandwidth portion #2 (BWP#2) (402). The base station may configure one or more bandwidth portions for the terminal and may configure the information in [Table 4] below for each bandwidth portion.

[0116] [Table 4]

[0117]

[0118] Of course, the above examples are not limited, and various parameters related to bandwidth portions may be configured for the terminal in addition to the above configuration information. The above information may be transmitted by the base station to the terminal via higher-layer signaling, for example, Radio Resource Control (RRC) signaling. At least one of the configured bandwidth portions may be activated. Whether a configured bandwidth portion is activated may be transmitted semi-statically from the base station to the terminal via RRC signaling or dynamically via Downlink Control Information (DCI).

[0119] According to one embodiment, prior to the RRC connection, a terminal may receive an Initial Bandwidth Part (Initial BWP) for initial connection from a base station via a Master Information Block (MIB). More specifically, during the initial connection phase, the terminal may receive configuration information regarding a Control Resource Set (CORESET) and a Search Space via the MIB, through which a Physical Downlink Control Channel (PDCCH) can be transmitted to receive System Information Blocks (System Information Block) required for initial connection. The Control Resource Set and Search Space configured via the MIB may each be considered as Identity (ID) 0 (CORESET 0, Search Space 0). The base station may notify the terminal via the MIB of configuration information, such as frequency allocation information, time allocation information, and subcarrier interval settings, for Control Resource Set #0. Additionally, the base station may notify the terminal via the MIB of configuration information regarding the monitoring period and monitoring occasion for Control Resource Set #0, i.e., configuration information for Search Space #0. The terminal may consider the frequency region set as control region #0 obtained from the MIB as the initial bandwidth portion for initial access. In this case, the identifier (ID) of the initial bandwidth portion may be considered as 0.

[0120] The settings for the bandwidth portion supported by the above 5G can be used for various purposes.

[0121] According to one embodiment, if the bandwidth supported by the terminal is smaller than the system bandwidth, this can be supported through the bandwidth portion setting. For example, by setting the frequency position of the bandwidth portion (setting information 2) to the terminal, the terminal can transmit and receive data at a specific frequency position within the system bandwidth.

[0122] In addition, according to one embodiment, a base station may set multiple bandwidth portions for a terminal for the purpose of supporting different subcarrier spacing settings. For example, to support data transmission and reception using both a 15 kHz subcarrier spacing and a 30 kHz subcarrier spacing for a terminal, two bandwidth portions may be set to subcarrier spacings of 15 kHz and 30 kHz, respectively. Different bandwidth portions may be frequency division multiplexed (FDM), and when data is to be transmitted and received at a specific subcarrier spacing, the bandwidth portion set to that subcarrier spacing may be activated.

[0123] In addition, according to some embodiments, a base station may set a bandwidth portion having different bandwidth sizes for the purpose of reducing the power consumption of the terminal. For example, if the terminal supports a very large bandwidth, such as 100 MHz, and always transmits and receives data using that bandwidth, very large power consumption may occur. In particular, in a situation where there is no traffic, performing monitoring of unnecessary downlink control channels using a large bandwidth of 100 MHz can be very inefficient in terms of power consumption. To reduce the power consumption of the terminal, the base station may set a bandwidth portion of a relatively small bandwidth, such as 20 MHz, for the terminal. In a situation where there is no traffic, the terminal can perform monitoring operations in the 20 MHz bandwidth portion, and when data is generated, it can transmit and receive data using the 100 MHz bandwidth portion according to the instructions of the base station.

[0124] In the method for configuring the above bandwidth portion, terminals prior to RRC connection (Connected) can receive configuration information for the Initial Bandwidth Part (Initial BWP) through the MIB during the initial connection phase. More specifically, the terminal can receive a configuration of a control area (i.e., CORESET) for a downlink control channel through which a DCI scheduling a System Information Block (SIB) can be transmitted from the MIB of the Physical Broadcast Channel (PBCH). The bandwidth of the control area configured based on the MIB can be considered as the Initial Bandwidth Part, and through the configured Initial Bandwidth Part, the terminal can receive the Physical Downlink Shared Channel (PDSCH) through which the SIB is transmitted. In addition to the purpose of receiving the SIB, the Initial Bandwidth Part may also be utilized for paging or random access.

[0125] Next, downlink control information (DCI) in 5G systems will be explained in detail.

[0126] In a 5G system, scheduling information for uplink data (or physical uplink shared channel (PUSCH)) or scheduling information for downlink data (or physical downlink shared channel (PDSCH)) can be transmitted from a base station to a terminal via DCI. The terminal can monitor the fallback DCI format and the non-fallback DCI format for PUSCH or PDSCH. The fallback DCI format may consist of fixed fields predefined between the base station and the terminal, and the non-fallback DCI format may include configurable fields.

[0127] DCI can be transmitted via the physical downlink control channel (PDCCH) after undergoing channel coding and modulation processes. A cyclic redundancy check (CRC) is attached to the DCI message payload, and the CRC can be scrambled with the terminal's identity identifier (e.g., radio network temporary identifier, RNTI). Different RNTIs may be used depending on the purpose of the DCI message, such as UE-specific data transmission, power control commands, or random access responses. In other words, the RNTI may not be transmitted explicitly but may be included in the CRC calculation process. Upon receiving a DCI message transmitted via the PDCCH, the terminal checks the CRC using the assigned RNTI; if the CRC check result is correct, the terminal knows that the message has been transmitted to it.

[0128] For example, a DCI scheduling a PDSCH for system information can be scrambled to SI-RNTI. For example, a DCI scheduling a PDSCH for a RAR message can be scrambled to RA-RNTI. For example, a DCI scheduling a PDSCH for a paging message can be scrambled to P-RNTI. A DCI notifying a SFI (slot format indicator) can be scrambled to SFI-RNTI. A DCI notifying a TPC (transmit power control) can be scrambled to TPC-RNTI. For example, a DCI scheduling a terminal-specific PDSCH or PUSCH can be scrambled to C-RNTI (cell RNTI).

[0129] A base station may operate by applying a predetermined DCI format to a terminal to be scheduled, depending on whether the DCI is for scheduling information for downlink data (downlink assignment), scheduling information for uplink data (uplink grant), and / or for DCI used for purposes other than data scheduling, such as power control.

[0130] The base station can transmit downlink data to the terminal via the Physical Downlink Shared Channel (PDSCH), which is a physical channel for downlink data transmission. Scheduling information, such as specific mapping locations in the time and frequency domains of the PDSCH, modulation schemes, HARQ-related control information, and power control information, can be provided by the base station to the terminal through the DCI related to downlink data scheduling information among the DCIs transmitted via the PDSCH.

[0131] The terminal can transmit uplink data to the base station via the PUSCH (physical uplink shared channel), which is a physical channel for uplink data transmission. Scheduling information, such as specific mapping locations in the time and frequency domains of the PUSCH, modulation schemes, HARQ-related control information, and power control information, can be provided by the base station to the terminal through the DCI related to uplink data scheduling information among the DCIs transmitted via the PDCCH.

[0132] The time-frequency resource to which the PDCCH is mapped is called the control resource set (CORESET). In the frequency domain, the CORESET can be set to all or part of the frequency resources within the bandwidth supported by the terminal. In the time domain, it can be set to one or more OFDM symbols, which can be defined as the CORESET duration. The base station can set one or more CORESETs to the terminal through higher-layer signaling (e.g., System Information, Master Information Block (MIB), Radio Resource Control (RRC) signaling). Setting the CORESET to the terminal may mean providing information such as the CORESET identifier, the frequency location of the CORESET, and the symbol length of the CORESET. The information provided by the base station to the terminal to set the CORESET may include at least some of the information included in [Table 5].

[0133] [Table 5]

[0134]

[0135] CORESET in the frequency domain It can be composed of RBs, and in the time domain It can be composed of symbols. A PDCCH can be composed of one or more Control Channel Elements (CCEs). One CCE can be composed of six Resource Element Groups (REGs), and a REG can be defined as one RB during one OFDM symbol. Within a single CoreSet, REGs can be indexed in Time-First order, starting with REG Index 0 from the first OFDM symbol of the CoreSet, which is the lowest RB. Interleaved and non-interleaved methods may be supported for the transmission of the PDCCH. The base station can configure the terminal to use interleaved or non-interleaved transmission for each CoreSet via upper-layer signaling. Interleaving can be performed on a REG bundle basis. A REG bundle can be defined as a set of one or more REGs. The terminal can determine the CCE-to-REG mapping method in the corresponding CORESET in the manner shown in [Table 6] below, based on whether the interleaving or non-interleaving transmission is set by the base station.

[0136] [Table 6]

[0137]

[0138] The base station can inform the terminal of configuration information, such as which symbol the PDCCH is mapped to within the slot and the transmission period, through signaling.

[0139] The search space of a PDCCH is described as follows. The number of CCEs required to transmit a PDCCH can be 1, 2, 4, 8, or 16 depending on the Aggregation Level (AL), and different numbers of CCEs can be used for link adaptation of the downlink control channel. For example, when AL=L, one downlink control channel can be transmitted through L CCEs. The terminal performs blind decoding to detect signals without knowing information about the downlink control channel; to this end, a search space representing a set of CCEs can be defined. The search space is a set of downlink control channel candidates consisting of CCEs that the terminal must attempt to decode at a given aggregation level. Since there are various aggregation levels that form a group of 1, 2, 4, 8, or 16 CCEs, the terminal may have multiple search spaces. A Search Space Set can be defined as a set of search spaces at all established aggregation levels.

[0140] Search spaces can be classified into Common Search Spaces (CSS) and UE-specific Search Spaces (USS). A certain group of terminals or all terminals may monitor the Common Search Space of the PDCCH to receive cell-common control information, such as dynamic scheduling or paging messages for System Information Blocks (SIBs). For example, a terminal may receive scheduling allocation information for the PDSCH for receiving system information by monitoring the Common Search Space of the PDCCH. In the case of the Common Search Space, since a certain group of terminals or all terminals must receive the PDCCH, it may be defined as a set of pre-agreed CCEs. Scheduling allocation information for the UE-specific PDSCH or PUSCH may be received by the terminal by examining the UE-specific Search Space of the PDCCH. The UE-specific Search Space may be defined specifically as a function of the terminal's ID (Identity) and various system parameters.

[0141] The base station may set configuration information for the search space of the PDCCH to the terminal through upper-layer signaling (e.g., SIB, MIB, RRC signaling). For example, the base station may set to the terminal the number of PDCCH candidates at each aggregation level L, the monitoring period for the search space, the occasion for monitoring in slot-symbol units for the search space, the search space type (common search space or terminal-specific search space), the combination of DCI format and RNTI to be monitored in the search space, and the CORESET index to be monitored in the search space. For example, parameters for the search space of the PDCCH may include at least one of the information shown in [Table 7] below.

[0142] [Table 7]

[0143]

[0144]

[0145]

[0146] According to the configuration information, the base station may configure one or more sets of search spaces for the terminal. According to one embodiment, the base station may configure search space set 1 and search space set 2 for the terminal. In search space set 1, the terminal may be configured to monitor DCI format A scrambled with X-RNTI in a common search space, and in search space set 2, the terminal may be configured to monitor DCI format B scrambled with Y-RNTI in a terminal-specific search space. According to the configuration information, one or more sets of search spaces may exist in the common search space or the terminal-specific search space. For example, search space set #1 and search space set #2 may be configured as a common search space, and search space set #3 and search space set #4 may be configured as terminal-specific search spaces.

[0147] In a common search space, the terminal may monitor at least one of the following combinations of DCI format and RNTI. However, the scope of the rights of the present disclosure is not limited to the following examples.

[0148] - DCI format 0_0 / 1_0 with CRC scrambled by C-RNTI, CS-RNTI, SP-CSI-RNTI, RA-RNTI, TC-RNTI, P-RNTI, SI-RNTI

[0149] - DCI format 2_0 with CRC scrambled by SFI-RNTI

[0150] - DCI format 2_1 with CRC scrambled by INT-RNTI

[0151] - DCI format 2_2 with CRC scrambled by TPC-PUSCH-RNTI, TPC-PUCCH-RNTI

[0152] - DCI format 2_3 with CRC scrambled by TPC-SRS-RNTI

[0153] Terminal—In a specific search space, the terminal may monitor at least one of the following combinations of DCI formats and RNTI. However, the scope of the rights of the present disclosure is not limited to the following examples.

[0154] - DCI format 0_0 / 1_0 with CRC scrambled by C-RNTI, CS-RNTI, TC-RNTI

[0155] - DCI format 1_0 / 1_1 with CRC scrambled by C-RNTI, CS-RNTI, TC-RNTI

[0156] RNTIs may follow at least one of the following definitions and uses.

[0157] C-RNTI (Cell RNTI): Used for terminal-specific PDSCH or PUSCH scheduling

[0158] TC-RNTI (Temporary Cell RNTI): Used for terminal-specific PDSCH scheduling

[0159] CS-RNTI (Configured Scheduling RNTI): Used for semi-static terminal-specific PDSCH scheduling.

[0160] RA-RNTI (Random Access RNTI): Used for PDSCH scheduling during the random access phase.

[0161] P-RNTI (Paging RNTI): Used for PDSCH scheduling where paging is transmitted.

[0162] SI-RNTI (System Information RNTI): Used for PDSCH scheduling where system information is transmitted.

[0163] INT-RNTI (Interruption RNTI): Used to indicate whether PDSCH has been punctured.

[0164] TPC-PUSCH-RNTI (Transmit Power Control for PUSCH RNTI): Used to instruct power control commands to the PUSCH

[0165] TPC-PUCCH-RNTI (Transmit Power Control for PUCCH RNTI): Used to instruct power control commands to the PUCCH

[0166] TPC-SRS-RNTI (Transmit Power Control for SRS RNTI): Used to instruct power regulation commands to the SRS

[0167] The DCI formats described above may follow the definitions in [Table 8] below.

[0168] [Table 8]

[0169]

[0170] The search space of aggregation level L in CORESET p and search space set s can be expressed as [Equation 1] below.

[0171] [Mathematical Formula 1]

[0172]

[0173] The value may be 0 for the common search space.

[0174] In the case of a terminal-specific search space, the value may correspond to a value that changes according to the terminal's ID (C-RNTI or the ID set by the base station for the terminal) and the time index.

[0175] The following describes in detail how a terminal measures channel conditions in a 5G communication system and reports them to a base station.

[0176] Channel state information (CSI) may include at least one of the following information.

[0177] - Channel Quality Indicator (CQI): CQI index indication information consisting of a modulation scheme and coding rate that satisfy the predefined minimum receive error rate of PDSCH.

[0178] - Precoding Matrix Indicator (PMI): Precoding matrix indicator information selected by the terminal

[0179] - CRI (CSI-RS resource indicator): CSI-RS information measured by the terminal

[0180] - RI (Rank Indicator): Rank indicator information selected by the terminal

[0181] -LI (Layer indicator): Indicator information for the best layer among the precoding matrices reported by the terminal

[0182] -SSBRI (SS / PBCH block resource indicator): SSB information measured by the terminal

[0183] - L1-RSRP (Reference Signal Received Power): L1 RSRP information measured by the terminal

[0184] The base station can control at least one of the time and frequency resources for the aforementioned CSI measurement and reporting of the terminal.

[0185] For CSI measurement and reporting operations, 'Aperiodic', 'Semi-Persistent', and 'Periodic' methods are supported, and the base station can configure which method to use for the terminal via signaling. Semi-persistent CSI reporting methods may support 'Semi-PersistentOnPUCCH' and 'Semi-PersistentOnPUSCH'. In the case of periodic or semi-persistent CSI reporting methods, the terminal can receive the PUCCH or PUSCH resources to transmit the CSI from the base station via upper-layer signaling. The period and slot offset of the PUCCH or PUSCH resources to transmit the CSI can be provided by the subcarrier interval setting of the uplink (UL) bandwidth part configured for CSI reporting transmission. In the case of a non-periodic CSI reporting method, the terminal can receive a PUSCH resource to transmit the CSI from the base station via L1 signaling (the aforementioned DCI format 0_1) through scheduling.

[0186] Non-periodic CSI reporting by the terminal can utilize PUSCH, and periodic CSI reporting can utilize PUCCH. Additionally, semi-permanent CSI reporting can be performed using PUSCH when triggered or activated by DCI, and using PUCCH after being activated by a MAC control element (MAC CE).

[0187] Non-periodic CSI reporting can be triggered by the "CSI request" field of the aforementioned DCI format 0_1, which corresponds to the scheduling DCI for PUSCH.

[0188] As a measure to support ultra-high-speed data services, 5G systems can support signal transmission and reception with ultra-wide bandwidths of tens to hundreds of MHz or several GHz. The above ultra-wide bandwidth signal transmission and reception can be supported through a single component carrier (CC) or through Carrier Aggregation (CA) technology that combines multiple component carriers. Carrier aggregation technology enables ultra-high-speed data services by increasing the total frequency bandwidth when a mobile operator has not secured a frequency bandwidth sufficient for providing ultra-high-speed data services through a single component carrier, by combining individual component carriers with relatively small bandwidths.

[0189] As mentioned above, the frequency bands utilized by 5G systems range from hundreds of MHz to tens of GHz.

[0190] FIG. 5 shows the interrelationship between frequency band, coverage, and bandwidth according to one embodiment of the present disclosure.

[0191] Figure 5 illustrates the frequency bands of the low band (501), mid band (502), high band (503), and ultra-high band (504). Generally, the lower the frequency band, the greater the coverage due to relatively lower path loss, while the higher the frequency band, the smaller the coverage due to relatively higher path loss. In the low frequency band, frequencies available for mobile communication are fragmented, resulting in a small bandwidth, whereas in the high frequency band, it is relatively easy to secure wide bandwidth frequencies, making it suitable for ultra-high-speed data services. As mobile communication systems evolve, efforts are being made to discover and utilize new frequency bands. For example, the next-generation mobile communication system, 6G (6 thIn generation mobile communication systems, the 7 to 15 GHz band, called the upper midband, is being considered as one of the candidate frequencies.

[0192] Generally, mobile carriers can secure multiple frequency bands to provide mobile communication services to users. For example, a mobile carrier can operate a combined LTE and 5G system by combining existing frequency bands for LTE systems with newly secured frequency bands for 5G systems. As another example, a mobile carrier can secure frequency bands for 5G systems across multiple bands and then combine the frequencies from those bands to provide mobile communication services through 5G CA. Similarly, a 6G mobile communication system can provide mobile communication services through 6G CA by combining 6G frequencies with existing 4G or 5G frequencies, or by combining 6G frequencies with each other.

[0193] As mentioned above, since characteristics such as coverage and bandwidth vary depending on the frequency band, there is a growing trend toward mobile communication services that combine multiple frequency bands rather than those relying on a single frequency band.

[0194] As another measure to support ultra-high-speed data services, data rates can be increased through spatial multiplexing using multiple transmitting and receiving antennas. Generally, the number of required power amplifiers (PAs) may increase in proportion to the number of transmitting antennas equipped in a base station or terminal. The maximum output of the base station and terminal depends on the characteristics of the power amplifiers, and generally, the maximum output of a base station may vary depending on the cell size it covers. Typically, maximum output can be expressed in dBm units. The maximum output of a terminal is usually 23 dBm or 26 dBm.

[0195] As an example of a commercial 5G base station, the base station may be equipped with 64 transmitting antennas and corresponding 64 power amplifiers in the 3.5 GHz frequency band and operate at a bandwidth of 100 MHz. Consequently, the energy consumption of the base station may increase in proportion to the output of the power amplifiers and the operating time of the power amplifiers. Compared to LTE base stations, 5G base stations have a relatively higher operating frequency band, which may be characterized by a wide bandwidth and a large number of transmitting antennas. While this characteristic has the effect of increasing the data rate, it may result in costs associated with increased energy consumption of the base station. Therefore, the more base stations constituting a mobile communication network there are, the greater the energy consumption of the entire mobile communication network may increase in proportion to that number.

[0196] As described above, the energy consumption of a base station can be significantly influenced by the operation of the power amplifier. Since the power amplifier is involved in the base station's transmission operation, the base station's downlink (DL) transmission operation may be highly correlated with the base station's energy consumption. Relatively speaking, the base station's uplink (UL) reception operation may not account for a large portion of the base station's energy consumption. The physical channel and physical signal transmitted by the base station via the downlink are as follows.

[0197] - PDSCH (Physical Downlink Shared Channel): A downlink data channel containing data to be transmitted to one or more terminals.

[0198] -PDCCH (Physical Downlink Control Channel): A downlink control channel containing scheduling information for PDSCH and PUSCH (Physical Uplink Control Channel). Alternatively, PDCCH alone can transmit control information such as slot formats and power control commands without PDSCH or PUSCH to be scheduled. The scheduling information may include at least one of resource information mapped to PDSCH or PUSCH, HARQ-related information, and power control information.

[0199] - PBCH (Physical Broadcast Channel): A downlink broadcast channel that provides the MIB (Master Information Block), which is essential system information required for the transmission and reception of the terminal's data and control channels.

[0200] -PSS (Primary Synchronization Signal): A signal that serves as the reference for DL ​​time / frequency synchronization and can provide some information about the cell ID.

[0201] -SSS (Secondary Synchronization Signal): A signal that serves as the reference for DL ​​time and / or frequency (hereinafter time / frequency) synchronization and provides the cell ID and some other information.

[0202] -DM-RS (Demodulation Reference Signal): A reference signal for terminal channel estimation for each of PDSCH, PDCCH, and PBCH.

[0203] - CSI-RS (Channel-state Information Reference Signal): A downlink signal that serves as a reference for measuring the downlink channel state of a terminal.

[0204] -PT-RS (Phase-tracking Reference Signal): Downlink signal for phase tracking

[0205] As an example of base station energy saving, stopping downlink transmission operations can enhance the energy saving effect by halting power amplifier operations. Additional energy savings may be possible by reducing the operation of other base station devices, such as baseband equipment, in addition to power amplifiers. Similarly, even though uplink reception operations account for a relatively small portion of the base station's total energy consumption, additional energy savings can be achieved if uplink reception operations can be stopped.

[0206] Various methods for saving base station energy will be explained below with reference to FIGS. 6, 7, 8, and 9.

[0207] - Base station energy saving method 1: The downlink transmission operation of a base station may depend on the amount of downlink traffic. For example, if there is no data to be transmitted to a terminal via the downlink, the base station does not need to transmit PDSCH and PDCCH for scheduling PDSCH. Or, if transmission can be temporarily suspended for reasons such as the data not being sensitive to transmission delay, the base station may not transmit PDSCH or / and PDCCH. An example of this is illustrated in FIG. 6. FIG. 6 is a diagram illustrating an example of a base station energy saving method according to an embodiment of the present disclosure. Referring to FIG. 6, in one embodiment, the amount of traffic that the base station intends to transmit may be maintained at a level higher than a threshold during the T1 period (610) and the T3 period (630), and the amount of traffic that the base station intends to transmit may be maintained at a level lower than a threshold during the T2 period (620). At this time, the base station can save energy by stopping or minimizing the operation of at least one of the base station power amplifier operation, base station RF device, and baseband device by not transmitting the PDSCH for data transmission and the PDCCH for scheduling the PDSCH during the T2 period. Additionally, if the traffic intended to be processed during the T2 period is not sensitive to transmission delay, the base station may defer transmission during the T2 period and perform delayed transmission during the T3 period. On the other hand, during the T1 and T3 periods, the PDSCH (602) for data transmission and the PDCCH (601) for scheduling the PDSCH can be transmitted without restriction so that there is no hindrance to the provision of communication services by the base station. The state of the base station during the T1 and T3 periods may be referred to as the base station normal state, and the state of the base station during the T2 period may be referred to as the base station energy saving state (ES state).The threshold for the above traffic amount may be communicated to the base station by a higher-level entity governing base station operations via signaling, or the base station may determine it on its own.

[0208] - Base station energy saving method 2: At least one physical channel and physical signal among PSS, SSS, PBCH, and CSI-RS is characterized by being repeatedly transmitted at a predetermined period regardless of data transmission to the terminal. Accordingly, even if the terminal does not receive data, it can continuously update at least one of downlink time / frequency synchronization, downlink channel status, and radio link quality. That is, at least one of PSS, SSS, PBCH, and CSI-RS can be transmitted through the downlink regardless of downlink data traffic, and this may cause base station energy consumption. Therefore, base station energy can be saved by controlling the transmission of signals unrelated to (or less relevant to) data traffic to occur less frequently. An example of this is explained through FIG. 7. FIG. 7 is a diagram illustrating an example of a base station energy saving method according to an embodiment of the present disclosure. Referring to FIG. 7, in one embodiment, during the base station normal state periods T1 (710) and T3 (730), the base station may transmit at least one periodic signal (703) of PSS, SSS, PBCH, or CSI-RS with a predefined transmission period 1 (701). On the other hand, during the base station power saving state period T2 (720), the base station may save base station energy by transmitting a periodic signal (704) with a transmission period 2 (702) that is relatively longer than the transmission period 1 (701), thereby intermittently performing or minimizing the operation of at least one of the base station power amplifier operation, base station RF device, and baseband device.

[0209] - Base station energy saving method 3: A base station can reduce energy consumption by switching off at least some of the base station's antennas or power amplifiers. An example of this is illustrated in FIG. 8. FIG. 8 is a diagram illustrating an example of a base station energy saving method according to an embodiment of the present disclosure. Referring to FIG. 8, in an embodiment, during the base station normal state T1 interval (810) and T3 interval (830), the base station can transmit a downlink signal based on at least one of a predefined transmission power 1 or M1 transmission antennas (801). On the other hand, during the base station power saving state T2 interval (820), the base station can reduce energy consumption by transmitting a downlink signal based on a transmission power 2 that is smaller than the transmission power 1 or M2 transmission antennas (802) that are relatively smaller than the M1 transmission antennas (801), thereby stopping or minimizing the operation of at least one of the base station power amplifier operation, base station RF device, and baseband device.

[0210] - Base station energy saving method 4: In an environment where carrier bundles are applied, when the amount of traffic that the base station intends to transmit is kept low below a threshold, the base station transmits the traffic through a predetermined configuration carrier and switches off the remaining configuration carriers, thereby stopping or minimizing the operation of at least one of the power amplifier operation, RF device, and baseband device of the switched-off configuration carriers, and saving base station energy. An example of this is explained through FIG. 9. FIG. 9 is a diagram illustrating an example of a base station energy saving method according to an embodiment of the present disclosure. Referring to FIG. 9, an example is illustrated in which configuration carrier 1 (901) and configuration carrier 2 (902) are operated as a carrier bundle. In the example of FIG. 9, the amount of traffic that the base station intends to transmit may be maintained above a threshold during the T1 period (910) and the T3 period (930), and the amount of traffic that the base station intends to transmit may be maintained below a threshold during the T2 period (920). In this case, to save energy, the base station may operate the T2 period in a base station power saving state, switch off configuration carrier 2 (902), and have configuration carrier 1 (901) handle the traffic processing during the T2 period. On the other hand, during the T1 period (910) and the T3 period (930), which are the base station normal state, both configuration carrier 1 (901) and configuration carrier 2 (902) are activated to quickly process a relatively large amount of traffic.

[0211] The above-described base station energy saving methods 1, 2, 3, and 4 can be applied and operated individually, or combined and operated together.

[0212] In the above description, the base station state is described in two stages: the base station general state and the base station power saving state; however, the base station power saving state can be distinguished and described in more detail. For example, the base station power saving state can be linked with the base station energy saving method, so that base station power saving state 1 represents the base station power saving state according to the base station energy saving method 1, base station power saving state 2 represents the base station power saving state according to the base station energy saving method 2, base station power saving state 3 represents the base station power saving state according to the base station energy saving method 3, and base station power saving state 4 represents the base station power saving state according to the base station energy saving method 4.

[0213] The operation of the system proposed in the present disclosure is explained below through specific embodiments.

[0214] The main point of the present disclosure is that, even if the base station is in a base station power saving state, the base station may transmit a discovery signal to facilitate base station identification by the terminal. The discovery signal may be transmitted by the base station to the terminal to inform it of the presence of the base station or cell. In one embodiment, the discovery signal may be a sequence-based signal similar to a synchronization signal and may be composed of a combination of one or more sequences. The discovery signal may be transmitted periodically, and by transmitting it with a relatively long transmission periodicity, a base station power saving effect can be expected during the period when the discovery signal is not transmitted. The present disclosure may define a discovery process in which the terminal detects the discovery signal. In one embodiment, the terminal that detects the discovery signal may recognize that a cell transmitting the discovery signal exists in the vicinity of the terminal. Accordingly, the terminal may transmit a terminal request signal requesting the base station to transmit a synchronization signal, and the base station may transmit a synchronization signal to the terminal in response to the terminal request. In this disclosure, a synchronization signal responding to a terminal request as described above may be referred to as an on-demand SSB. In one embodiment, the terminal can rapidly acquire time and frequency synchronization through the on-demand SSB. In one embodiment, the on-demand SSB may be composed of at least one of PSS, SSS, and PBCH, or a combination of the at least one thereof. In one embodiment, the base station may provide seamless communication services to terminals within the cell by switching the base station state from a base station power saving state to a base station normal state before and after the transmission of the on-demand SSB. In one embodiment, in the base station normal state, the base station may transmit an SSB in accordance with a predefined transmission cycle, independently of the transmission of the on-demand SSB.Accordingly, a separate terminal request for SSB transmission is not required, so it can be free from errors in transmitting and receiving terminal request signals. In one embodiment, a terminal that has successfully received the SSB can obtain cell-common transmission and reception related control information from the base station's SIB. In one embodiment, the terminal can transmit a random access preamble to initiate a random access procedure by referring to the control information of the SIB.

[0215] The following initial access procedure may be understood to include at least one of the discovery signal between the terminal and the base station, the terminal request signal, the on-demand SSB, the transmission and reception of SSB and system information, and the random access procedure between the terminal and the base station. Subsequently, the terminal may request an attach to the network, and after the attach procedure is completed, may transmit and receive packets (or data) through the network.

[0216] The following is a description of each specific embodiment. The present disclosure may include a plurality of embodiments, each of which is distinguished for convenience to explain the implementation according to the present disclosure and may be implemented independently; however, as long as they are not mutually exclusive, all or part of the plurality of embodiments may be selectively combined and implemented. Such combinations include various variations and modifications of the present disclosure and may be made in various ways depending on technical needs or application environments. Even if the plurality of embodiments use different approaches to achieve the purpose of the invention, they may be used simultaneously or complementarily as long as the embodiments of the present invention are not technically mutually exclusive. Such combinations may be varied depending on technical requirements or specific application cases, and the present disclosure may encompass various embodiments including such variations and combinations. Although the name of a 5G system is used to describe the embodiments of the present disclosure, this is merely an example and can be understood as a message that includes information or performs the same role as described below.

[0217] <1st Embodiment>

[0218] The first embodiment describes a discovery process for detecting a discovery signal in the initial connection procedure of the terminal described above.

[0219] As described above, even if the base station is in a base station power saving state, the base station may transmit a discovery signal to facilitate base station identification by the terminal. Hereinafter, the process by which the terminal recognizes the presence of a base station or cell from the discovery signal may be referred to as cell discovery. By transmitting the discovery signal with a relatively long transmission cycle, the base station can expect a base station power saving effect during the period when the discovery signal is not transmitted. In addition, by limiting the number of base station transmitting antennas used to transmit the discovery signal to a smaller number than the number of transmitting antennas used by the base station in the normal state, a base station power saving effect can be expected when transmitting the discovery signal.

[0220] From a discovery signal having the characteristics described above, the terminal can perform cell discovery through the following method.

[0221] - Method 1: The terminal can determine cell discovery based on the received signal strength of the discovery signal. For example, if the following mathematical formula is satisfied, the terminal can determine that cell discovery has been successful.

[0222] [Mathematical Formula 2]

[0223] Q1_discovery > Threshold 1

[0224] ■Q1_discovery: This is the Received Signal Strength (RSRP) measured by the terminal from the discovery signal. For example, it may represent the average power value of the discovery signal measured by the terminal through the radio resource to which the discovery signal is mapped.

[0225] ■Threshold 1: A threshold value for determining whether cell discovery has occurred. This value may be mutually agreed upon between the terminal and the base station, or the base station may inform the terminal through signaling. If the terminal has a history of recently transmitting and receiving data with the base station, the terminal may update threshold 1 by referring to relevant information. For example, the terminal may update threshold 1 by referring to the channel state information between the terminal and the base station from the previous T1 time point to the current time point relative to the current time point.

[0226] - Method 2: The terminal can determine cell discovery based on the received signal quality of the discovery signal. For example, if the following mathematical formula is satisfied, the terminal can determine that cell discovery has been successful.

[0227] [Mathematical Formula 3]

[0228] Q2_discovery > Threshold 2

[0229] ■Q2_discovery: This is the received signal quality (RSRQ) measured by the terminal from the discovery signal. For example, it may represent the ratio of the average power value of the discovery signal and the average power value of the interference signal measured by the terminal through the radio resource to which the discovery signal is mapped.

[0230] ■Threshold 2: Another threshold value for determining whether cell discovery has occurred. This value may be mutually agreed upon between the terminal and the base station, or the base station may inform the terminal through signaling. If the terminal has a history of recently transmitting and receiving data with the base station, the terminal may update threshold 1 by referring to the relevant information. For example, the terminal may update threshold 1 by referring to the channel state information between the terminal and the base station from the previous T1 time point to the current time point relative to the current time point.

[0231] - Method 3: By combining the above Method 1 and Method 2, the terminal can determine that cell discovery has been successful if the measured discovery signal satisfies both [Equation 2] and [Equation 3].

[0232] Referring to FIG. 10 below, the cell discovery procedure of the terminal is described. In step 1001, the terminal can detect a discovery signal and perform a measurement operation.

[0233] In step 1002, the terminal can determine whether the measurement result of the discovery signal satisfies the cell discovery success condition according to the cell discovery method described above.

[0234] In one embodiment, if the terminal determines that it has succeeded in cell discovery, in step 1003, the terminal may transmit a terminal request signal requesting the base station to transmit an on-demand SSB. In one embodiment, the terminal that transmitted the terminal request signal may attempt to receive an on-demand SSB from the base station. In one embodiment, if the terminal has not succeeded in cell discovery, the terminal may repeat the procedure of step 1001.

[0235] As a modified example of the first embodiment, beamforming technology may be applied to increase the propagation range by concentrating the radiated energy of a discovery signal in a predetermined target direction in order to secure sufficient coverage with limited base station transmission power. A signal to which beamforming technology is applied has a relatively narrow beam width, and since the radiated energy is concentrated within the narrowed beam width, the propagation range may be increased. Therefore, in order to transmit the discovery signal in all directions centered on the base station, a beam sweeping operation may be required to transmit the discovery signal by changing the beam direction multiple times. For example, each discovery signal can be transmitted via beam sweeping for a total of L beam directions. For the discovery signal to which beam sweeping is applied, the terminal may perform cell discovery in at least one of the following ways.

[0236] - Method 1: For each discovery signal measurement value to which beam sweeping is applied, it can be determined whether at least one of the cell discovery criteria [Equation 2] or [Equation 3] is satisfied. For example, if at least one measurement value among up to L discovery signal measurements satisfies at least one of the cell discovery criteria [Equation 2] or [Equation 3], the terminal can ultimately determine that the cell discovery criteria are satisfied.

[0237] - Method 2: For a discovery signal to which beam sweeping is applied, up to L measurement values ​​are combined to convert them into a single representative measurement value, and then it is determined whether at least one of the cell discovery criteria in [Equation 2] or [Equation 3] is satisfied. The method of combining up to L measurement values ​​may be done by summing the L measurement values ​​or by calculating the average value of the L measurement values.

[0238] Although the names of 5G systems have been used to describe the embodiments of the present disclosure, the names such as discovery signal, on-demand SSB described above are merely examples and can be understood as messages that include information or perform the same role as described above.

[0239] <Second Embodiment>

[0240] A second embodiment describes an initial connection procedure of a terminal including the cell discovery procedure of the terminal described above.

[0241] With reference to FIG. 11 below, the initial connection procedure of a terminal is described. In step 1101, the terminal may perform a cell discovery procedure. Through the specific method described above, the terminal may determine whether there is at least one base station or cell transmitting a discovery signal in the vicinity of the terminal. If the terminal succeeds in cell discovery, the terminal may transmit a terminal request signal to the base station requesting the transmission of an on-demand SSB. In one embodiment, the base station may transmit an on-demand SSB to the terminal in response to the terminal request signal. Through the on-demand SSB, the terminal can quickly acquire time and frequency synchronization. In one embodiment, the base station may switch the base station state from a base station power saving state to a base station normal state before and after the transmission of the on-demand SSB to provide seamless communication services to terminals within the cell. In one embodiment, in the base station normal state, the base station may transmit an SSB in accordance with a predefined transmission cycle, separately from the transmission of the on-demand SSB. In one embodiment, if the terminal fails to succeed in cell discovery, step 1101 can be repeated.

[0242] In one embodiment, if the terminal succeeds in cell discovery, in step 1102, the terminal may perform a PLMN selection procedure to identify the mobile communication network. PLMN (Public Land Mobile Network) refers to a mobile communication network, and each mobile communication operator may be assigned a unique identifier (PLMN ID). The base station may transmit the PLMN ID included as control information in the SIB. In step 1102, the terminal may determine whether the PLMN ID obtained from the SIB matches its subscriber information. In one embodiment, to decode the SIB, the terminal may synchronize time and frequency from the SSB transmitted by the base station, obtain a cell identifier, and obtain control information necessary for receiving the SIB from the control information included in the PBCH. In one embodiment, a situation may occur where the cell (Cell #1) obtained by the terminal through the cell discovery procedure of step 1101 and the cell (Cell #2) identified through the PLMN selection procedure of step 1102 are inconsistent with each other (Cell #1 ≠ Cell #2). If Cell #1 ≠ Cell #2, the terminal may perform the next step by applying at least one of the following methods.

[0243] - Method 1: Subsequent steps can be performed based on Cell #2 identified in the PLMN selection step corresponding to the most recent terminal processing. For example, in step 1103, the terminal can proceed with the cell selection procedure with priority given to Cell #2.

[0244] - Method 2: Subsequent steps can be performed based on Cell #1 identified in the cell discovery step corresponding to the initial terminal processing. For example, in step 1103, the terminal can prioritize Cell #1 and proceed with the cell selection procedure.

[0245] In one embodiment, when the terminal completes the PLMN selection procedure, the terminal may perform a cell selection procedure in step 1103. In the cell selection procedure, the terminal may determine whether the measurement value of the SSB transmitted by the base station meets the cell selection criteria. For example, if the received signal strength of the SSB measured by the terminal is greater than the threshold value according to the cell selection criteria, the terminal may determine that the cell to which the SSB belongs satisfies the cell selection criteria. For a cell that satisfies the cell selection criteria, the terminal may receive a SIB. Then, the terminal may transmit a random access preamble to initiate a random access procedure or receive paging information by referring to the cell-common transmission and reception control information included in the SIB.

[0246] A situation may occur where the cell (Cell #1) obtained by the terminal through the cell discovery procedure of step 1101 above and the cell (Cell #3) confirmed through the cell selection procedure of step 1103 are inconsistent with each other (Cell #1 ≠ Cell #3). If Cell #1 ≠ Cell #3, the terminal may perform the next step by applying the following method A.

[0247] - Method A: Subsequent steps can be performed based on Cell #3 identified in the cell selection step corresponding to the most recent terminal processing.

[0248] Although the names of 5G systems have been used to describe the embodiments of the present disclosure, the names such as discovery signal, on-demand SSB, SSB, SIB, etc. described above are merely examples and can be understood as messages that include information or perform the same role as described above.

[0249] <Third Embodiment>

[0250] A third embodiment describes a method for measuring a terminal in the initial connection procedure of the terminal described above.

[0251] Referring to FIG. 12 below, an example of a terminal measurement method when the terminal receives a discovery signal is described. In the example of FIG. 12, the x-axis represents the time domain and the y-axis represents the strength of the received signal. In one embodiment, the terminal can perform a measurement of the discovery signal based on the discovery signal collected during a predetermined measurement window (1210) time interval and make a determination regarding whether cell discovery is successful. The example of FIG. 12 shows that the terminal collected measurement samples for a total of 6 discovery signals, s1 (1201), s2 (1202), s3 (1203), s4 (1204), s5 (1205), and s6 (1206), during the measurement window time interval. At this time, if the number of measurement samples (N) in which the received signal strength of the discovery signal is greater than the threshold value (1220) is greater than the predefined number K (N > K), the terminal can determine that cell discovery has succeeded. Conversely, if N ≤ K, it can determine that cell discovery has failed. In the example of FIG. 12, for instance, if K = 2, there are a total of 3 measurement samples (N = 3 > K) that exceed the threshold value, such as s1 (1201), s5 (1205), and s6 (1206). Therefore, the terminal can determine that cell discovery has succeeded. The parameters such as the measurement window, threshold value, and K can be set and operated by the terminal itself, or determined by the base station and notified to the terminal through signaling. FIG. 12 is shown based on the signal strength of the discovery signal received by the terminal, but it can be shown based on the received signal quality that also considers interference signals. In addition, the signal to be measured by the terminal can be extended to include not only the discovery signal but also SSB, etc. In this case, parameters such as the measurement window, threshold, and K corresponding to the SSB measurement can be set separately.

[0252] <Fourth Embodiment>

[0253] The fourth embodiment describes the terminal and base station procedures according to the initial connection procedure of the terminal described above.

[0254] With reference to FIG. 13 below, the operation of a terminal and a base station according to an embodiment of the present disclosure will be described. As described above, the discovery signal may have the characteristic of being transmitted with a relatively long transmission period, the SSB may have the characteristic of being transmitted with a relatively short transmission period, and the on-demand SSB may have the characteristic of being transmitted in response to a terminal request signal. In an embodiment of FIG. 13, the transmission period of the discovery signal may be P1 (1330), and the transmission period of the SSB may be P2 (1340) (P1 > P2). Here, the discovery signal (1301) may be detected at P1 (1330). For convenience of explanation, a candidate time interval in which the discovery signal may be transmitted is referred to as the discovery signal transmission occasion (1310), and a candidate time interval in which the SSB may be transmitted is referred to as the SSB transmission occasion (1320). In the example of FIG. 13, it is assumed that the base station is in a base station power saving state during phase 1 (1350), and subsequently, during phase 2 (1360), the base station is in a base station normal state. In one embodiment, in the base station power saving state, the base station can achieve a base station power saving effect by omitting the periodically transmitted SSB transmission and transmitting a discovery signal with a relatively long transmission period. In one embodiment, an on-demand SSB (1304) can be transmitted according to a terminal request signal (1303) to respond quickly to a request from a terminal. In one embodiment, during phase 1 (1350), which is the base station power saving state (1370), the terminal attempts to detect the discovery signal at the discovery signal transmission occasion and does not attempt to detect the SSB at the SSB transmission occasion. Subsequently, during phase 2 (1360), which is the base station normal state (1370), the terminal attempts to detect the SSB at the SSB transmission occasion.

[0255] In one embodiment, if the terminal succeeds in detecting a discovery signal (1302) transmitted within a discovery signal transmission occasion at time T1 (1390), the terminal may transmit a terminal request signal (1303) requesting transmission of an on-demand SSB to the base station. Whether the terminal succeeds in cell discovery may follow the specific method described above. In one embodiment, the base station may transmit an on-demand SSB (1304) to the terminal in accordance with the terminal request signal. The terminal may obtain time and frequency synchronization of a certain level or higher from the received on-demand SSB (1304). In one embodiment, the base station may switch the base station state from a base station power saving state to a base station normal state in accordance with the terminal request signal, thereby performing normal transmission and reception operations. In one embodiment, the terminal may attempt to detect an SSB at every SSB transmission occasion during phase 2 (1360) in which the base station has switched to the base station normal state. In one embodiment, the terminal can synchronize time and frequency from SSBs (1306, 1307, 1308, 1309) transmitted by the base station in a normal state and obtain a cell identifier. Then, the terminal can obtain control information (e.g., at least one of the time and frequency resource information of the PDCCH) related to a PDCCH that schedules the SIB to be received in the next step (hereinafter referred to as SIB PDCCH) from the MIB obtained through the SSB. Subsequently, the terminal can obtain a SIB by receiving the SIB PDCCH and the PDSCH scheduled by the SIB PDCCH (hereinafter referred to as SIB PDSCH). The SIB may include a PLMN identifier and cell-common transmission and reception control information. The terminal can perform a PLMN selection procedure from the obtained PLMN identifier. Then, the terminal can perform a cell selection procedure from the received SSB.The terminal can transmit a random access preamble by referring to the control information of the SIB.

[0256] In one embodiment, for the terminal request signal transmitted by the terminal in phase 1, a relatively relaxed allowable range for transmit timing error may be applied under the assumption that the synchronization accuracy between the base station and the terminal is not relatively high. Conversely, a relatively strict allowable range for transmit timing error may be applied to the uplink signal transmitted by the terminal in phase 2. For example, the allowable range for the terminal's transmit timing error for the random access preamble in phase 2 may be maintained within ±Te, and the allowable range for the terminal's transmit timing error for the terminal request signal in phase 1 may be maintained within ±T'e (Te < T'e). Te and T'e may be applied differently depending on the frequency band. For example, Te = 0.23 usec.

[0257] The example in FIG. 13 above illustrates a case where beam sweeping operation of the SSB in a multi-beam environment is not considered, but it can be generalized to operate even when beam sweeping is applied. In one embodiment, the SSB transmitted at each SSB transmission occasion can be replaced with L SSBs, each corresponding to L different beams. Similarly, the discovery signal transmitted at each discovery signal transmission occasion can be replaced with K discovery signals, each corresponding to K different beams (K ≤ L). And the on-demand SSB can also be replaced with M on-demand SSBs, each corresponding to M different beams (M ≤ L).

[0258] Although the names of 5G systems have been used to describe the embodiments of the present disclosure, the names described above, such as discovery signal, on-demand SSB, SSB, PDCCH, PDSCH, SIB, etc., are merely examples and can be understood as messages that include information or perform the same role as described above.

[0259] FIG. 14 illustrates an example of terminal operation during an initial connection procedure according to an embodiment of the present disclosure. In step 1401, the terminal attempts to detect a discovery signal transmitted by a base station. In one embodiment, if the terminal successfully detects the discovery signal, the terminal may recognize that a cell exists around the terminal. Whether the terminal succeeds in cell discovery may follow the specific method described above. In one embodiment, a terminal that has succeeded in cell discovery may transmit a terminal request signal to the base station in step 1402 to request the transmission of an on-demand SSB. In one embodiment, the terminal that has transmitted the terminal request signal may attempt to receive an on-demand SSB in step 1403. In one embodiment, the terminal that has received the on-demand SSB may attempt to receive an SSB in step 1404. In one embodiment, the terminal may perform downlink time and frequency synchronization from the SSB received from the base station and obtain a cell identifier (cell ID). In one embodiment, the SSB includes at least one of a synchronization signal and a PBCH. In one embodiment, the terminal can obtain MIB, which is essential system information, in step 1404. In one embodiment, the terminal can receive a PBCH using a cell ID obtained from the synchronization signal and obtain MIB, which is essential system information, from the PBCH. In one embodiment, the MIB may include at least one of CORESET information or PDCCH configuration information, which are time-frequency resources to which the PDCCH is mapped. In step 1405, the terminal can monitor the SIB PDCCH by referring to the obtained PDCCH configuration information. In one embodiment, the terminal can obtain the SIB by receiving the SIB PDSCH from the scheduling information of the SIB PDCCH. In one embodiment, the SIB may include a PLMN identifier and cell-common transmission and reception related control information. In one embodiment, the terminal can perform a PLMN selection procedure from the obtained PLMN identifier.And the terminal can perform a cell selection procedure from the received SSB. The cell-common transmission and reception control information may include, for example, at least one of random access control information, paging control information, and common control information for various physical channels. In step 1406, the terminal can proceed with a random access procedure.

[0260] The steps described above may be modified, omitted, changed in order, or undesired steps may be added to carry out the present invention.

[0261] FIG. 15 is a diagram illustrating an example of base station operation to support a terminal initial connection procedure according to an embodiment of the present disclosure. In step 1501, the base station may transmit a discovery signal to notify terminals within cell coverage of the presence of the base station. In step 1502, the base station may attempt to receive a terminal request signal transmitted by a terminal. In step 1503, the base station that has received the terminal request signal may transmit an on-demand SSB in response to the terminal request signal. In one embodiment, the base station that has transmitted the on-demand SSB may transmit an SSB in step 1504. In one embodiment, the SSB may include at least one of a synchronization signal and a PBCH. In step 1505, the base station may transmit a SIB PDCCH and a SIB PDSCH for transmitting a SIB. In one embodiment, the SIB may include a PLMN identifier and cell-common transmission and reception related control information. Cell common transmission and reception related control information may include, for example, at least one of random access related control information, paging related control information, and common control information for various physical channels. In step 1506, the base station may proceed with a random access procedure based on a terminal request.

[0262] The steps described above may be modified, omitted, changed in order, or undesired steps may be added to carry out the present invention.

[0263] FIG. 16 is a drawing showing an example of a terminal transceiver in a wireless communication system according to an embodiment of the present disclosure. For convenience of explanation, devices not directly related to the present disclosure may be omitted from illustration and description.

[0264] Referring to FIG. 16, the terminal may be configured to include at least one of a transmitter (1604) composed of an uplink transmission processing block (1601), a multiplexer (1602), and a transmission RF block (1603), a receiver (1608) composed of a downlink reception processing block (1605), a demultiplexer (1606), and a reception RF block (1607), and a control unit (1609). The control unit (1609) can control each of the respective blocks of the receiver (1608) for receiving a data channel or control channel transmitted by the base station as described above, and at least one of the respective blocks of the transmitter (1604) for transmitting an uplink signal.

[0265] In the transmission unit (1604) of the terminal, the uplink transmission processing block (1601) can generate a signal to be transmitted by performing processes such as channel coding and modulation. The signal generated in the uplink transmission processing block (1601) can be multiplexed with other uplink signals by a multiplexer (1602), then processed by a transmission RF block (1603), and then transmitted to a base station.

[0266] The receiving unit (1608) of the terminal can demultiplex a signal received from a base station and distribute it to each downlink receiving processing block. The downlink receiving processing block (1605) can obtain control information or data transmitted by the base station by performing processes such as demodulation and channel decoding on the downlink signal of the base station. The receiving unit (1608) of the terminal can apply the output result of the downlink receiving processing block to the control unit (1609) to support the operation of the control unit (1609).

[0267] FIG. 17 is a block diagram showing an example of the configuration of a terminal according to one embodiment of the present disclosure.

[0268] As illustrated in FIG. 17, the terminal of the present disclosure may include at least one of a processor (1730), a transceiver (1710), or a memory (1720). However, the components of the terminal are not limited to the examples described above. For example, the terminal may include more components or fewer components than the components described above. Furthermore, at least one of the processor (1730), the transceiver (1710), and the memory (1720) may be implemented in the form of a single chip. According to one embodiment, the transceiver (1710) of FIG. 17 may include the transceiver (1604) and the receiver (1608) of FIG. 16. Additionally, the processor (1730) of FIG. 17 may include the control unit (1609) of FIG. 16.

[0269] According to one embodiment, the processor (1730) can control a series of processes that allow the terminal to operate according to the embodiments of the present disclosure described above. For example, according to the embodiments of the present disclosure, the components of the terminal can be controlled to perform a transmission and reception method of the terminal according to a discovery signal of a base station. The processor (1730) may include at least one processor, and the processor (1730) can perform a transmission and reception operation of the terminal in a wireless communication system applying the operation of the present disclosure described above by executing a program stored in memory (1720).

[0270] The transceiver (1710) can transmit and receive signals with a base station. The signals transmitted and received with the base station may include control information and data. The transceiver (1710) may be composed of an RF transmitter that up-converts and amplifies the frequency of a transmitted signal, and an RF receiver that low-noise amplifies a received signal and down-converts the frequency. However, this is merely an example of the transceiver (1710), and the components of the transceiver (1710) are not limited to an RF transmitter and an RF receiver. Additionally, the transceiver (1710) can receive a signal through a wireless channel and output it to a processor (1730), and transmit the signal output from the processor (1730) through a wireless channel.

[0271] According to one embodiment, the memory (1720) may store programs and data necessary for the operation of the terminal. Additionally, the memory (1720) may store control information or data included in signals transmitted and received by the terminal. The memory (1720) may be composed of a storage medium or a combination of storage media such as ROM, RAM, hard disk, CD-ROM, and DVD. Additionally, there may be multiple memory (1720). According to one embodiment, the memory (1720) may store a program for performing the transmission and reception operation of the terminal in accordance with the discovery signal transmission of the base station, which is one of the embodiments of the present disclosure described above.

[0272] FIG. 18 is a block diagram showing an example of the configuration of a base station according to one embodiment of the present disclosure.

[0273] As illustrated in FIG. 18, the base station of the present disclosure may include at least one of a processor (1830), a transceiver (1810), or a memory (1820). However, the components of the base station are not limited to the examples described above. For example, the base station may include more components or fewer components than the components described above. Furthermore, at least one of the processor (1830), the transceiver (1810), and the memory (1820) may be implemented in the form of a single chip.

[0274] The processor (1830) can control a series of processes to enable the base station to operate according to the embodiments of the present disclosure described above. For example, according to the embodiments of the present disclosure, the components of the base station can be controlled to perform a method of scheduling a terminal according to the transmission of a discovery signal of the base station. The processor (1830) may include at least one processor, and the processor (1830) can perform a method of scheduling a terminal according to the frequency instruction of the base station of the present disclosure described above by executing a program stored in memory (1820).

[0275] The transceiver (1810) can transmit and receive signals with a terminal. The signals transmitted and received with the terminal may include control information and data. The transceiver (1810) may be composed of an RF transmitter that up-converts and amplifies the frequency of a transmitted signal, and an RF receiver that low-noise amplifies a received signal and down-converts the frequency. However, this is merely an example of the transceiver (1810), and the components of the transceiver (1810) are not limited to an RF transmitter and an RF receiver. Additionally, the transceiver (1810) can receive a signal through a wireless channel and output it to a processor (1830), and transmit the signal output from the processor (1830) through a wireless channel.

[0276] According to one embodiment, the memory (1820) may store programs and data necessary for the operation of the base station. Additionally, the memory (1820) may store at least one of control information or data included in the signals transmitted and received by the base station. The memory (1820) may be composed of a storage medium or a combination of storage media such as ROM, RAM, hard disk, CD-ROM, and DVD. Additionally, there may be multiple memory (1820). According to one embodiment, the memory (1820) may store a program for performing a method of scheduling a terminal according to the transmission of a discovery signal of the base station, which is one of the embodiments of the present disclosure described above.

[0277] In the specific embodiments of the present disclosure described above, the components included in the present disclosure are expressed in a singular or plural form according to the specific embodiments presented. However, the singular or plural expression is selected to suit the situation presented for convenience of explanation, and the present disclosure is not limited to singular or plural components; even if a component is expressed in the plural form, it may be composed of a singular form, and even if a component is expressed in the singular form, it may be composed of a plural form.

[0278] Meanwhile, the present specification and drawings disclose preferred embodiments of the present disclosure. Although specific terms have been used, they are used merely in a general sense to facilitate the explanation of the technical content of the present disclosure and to aid in understanding the invention, and are not intended to limit the scope of the present disclosure. It is obvious to those skilled in the art that, in addition to the embodiments disclosed herein, other variations based on the technical concept of the present disclosure are possible. Furthermore, each of the above embodiments may be combined and operated as needed. For example, the first, second, and third embodiments may be implemented independently, or at least one of the embodiments may be combined and implemented.

[0279] Meanwhile, although specific embodiments have been described in the detailed description of the present disclosure, it is understood that various modifications are possible within the scope of the present disclosure. Therefore, the scope of the present disclosure should not be limited to the described embodiments, but should be defined by the claims set forth below as well as equivalents thereof.

Claims

1. In a method performed by a terminal in a wireless communication system, A step of identifying whether at least one characteristic of a cell discovery signal transmitted from a base station exceeds a threshold value; A step of determining that cell discovery is successful if at least one of the above characteristics exceeds the threshold value; and Based on the above decision, the method includes the step of transmitting a request signal requesting the transmission of an on-demand synchronization signal block (SSB) to the base station. The above base station is in a power saving state, method.

2. In Paragraph 1, A method in which at least one of the above characteristics is the received signal strength of the cell discovery signal, and the received signal strength is determined based on the average power value of the cell discovery signal.

3. In Paragraph 1, A method wherein at least one of the above characteristics is the reception signal quality of the cell discovery signal, and the reception signal quality is determined based on the ratio of the average power value of the cell discovery signal and the average power value of the interference signal.

4. In Paragraph 1, A method in which the above threshold value is determined by a value previously defined by the terminal and the base station, or by a value transmitted by the base station to the terminal.

5. In Paragraph 1, The above at least one characteristic is the received signal strength and received signal quality of the cell discovery signal, and The above received signal strength is determined based on the average power value of the cell discovery signal, and A method in which the received signal quality is determined based on the ratio of the average power value of the cell discovery signal and the average power value of the interference signal.

6. In Paragraph 1, A method further comprising the step of receiving the on-demand SSB from the base station.

7. A method according to claim 6, wherein when the terminal receives the on-demand SSB, the base station switches from the power saving state to a normal state.

8. In Paragraph 6, A step of receiving a system information block (SIB) including a public land mobile network (PLMN) ID (identifier) ​​and a cell identifier from the base station; and A method further comprising the step of selecting a PLMN based on the above SIB.

9. In Paragraph 8, A step of identifying whether a first cell based on the cell discovery signal and a second cell based on the cell identifier match; and A method further comprising the step of selecting the first cell or the second cell according to a predefined priority when the first cell and the second cell do not match.

10. In a terminal of a wireless communication system, Transmitter / receiver; and It includes at least one processor; and the at least one processor, Identifying whether at least one characteristic of a cell discovery signal transmitted from a base station exceeds a threshold, and If at least one of the above characteristics exceeds the threshold value, cell discovery is determined to be successful, and Based on the above decision, it is configured to transmit a request signal requesting the transmission of an on-demand synchronization signal block (SSB) to the base station, and The above base station is a terminal in a power saving state.

11. In Paragraph 10, A terminal, wherein at least one of the above characteristics is the received signal strength of the cell discovery signal, and the received signal strength is determined based on the average power value of the cell discovery signal.

12. In Paragraph 10, A terminal, wherein at least one of the above characteristics is the reception signal quality of the cell discovery signal, and the reception signal quality is determined based on the ratio of the average power value of the cell discovery signal and the average power value of the interference signal.

13. In Paragraph 10, A terminal, wherein the threshold value is determined by a value previously defined by the terminal and the base station, or by a value transmitted by the base station to the terminal.

14. In Paragraph 10, The above at least one characteristic is the received signal strength and received signal quality of the cell discovery signal, and The above received signal strength is determined based on the average power value of the cell discovery signal, and A terminal in which the received signal quality is determined based on the ratio of the average power value of the cell discovery signal and the average power value of the interference signal.

15. In paragraph 10, the above at least one processor, A terminal further configured to receive the on-demand SSB from the base station.

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