Method and apparatus for controlling prach transmission power according to prach adaptation for energy saving in wireless communication system

Abstract

The present disclosure relates to a 5G or 6G communication system for supporting higher data transmission rates. The present disclosure describes a PRACH transmission configuration and transmission method and apparatus for reducing energy consumption of a base station.

Description

Method and device for controlling PRACH transmission power according to PRACH adaptation for energy saving in wireless communication systems

[0001] The present disclosure relates to the operation of a terminal and a base station in a wireless communication system. Specifically, the present disclosure relates to a method and device for energy saving in a wireless communication system.

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

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

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

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

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

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

[0008] With the recent development of 5G / 6G communication systems that take the environment into consideration, the need for methods to reduce energy consumption of communication systems (e.g., terminals, base stations, networks, etc.) or methods for energy saving is emerging.

[0009] The present disclosure proposes a PRACH adaptation operation and a method and device for setting a PRACH adaptation operation to reduce energy consumption of a base station. The technical problems to be achieved in the present disclosure are not limited to the technical problems mentioned above, and other technical problems not mentioned will be clearly understood by those skilled in the art to which the present disclosure pertains from the description below.

[0010] According to one embodiment of the present disclosure, a method is provided, which is performed by a terminal of a communication system, comprising: receiving information on a default physical random access channel (PRACH) configuration and information on a PRACH configuration for PRACH adaptation from a base station; performing an initial PRACH transmission based on the default PRACH configuration or the PRACH configuration for PRACH adaptation; confirming that a response corresponding to the initial PRACH transmission is not received within a time window; determining transmission power for PRACH retransmission; and performing the PRACH retransmission at a PRACH occasion closer in the time domain among a PRACH occasion related to the default PRACH configuration or a PRACH occasion related to the PRACH configuration for PRACH adaptation at a time point at which the PRACH retransmission should be performed based on the transmission power.

[0011] In addition, in a method performed by a base station of a communication system, the method comprises: a step of transmitting information on a default PRACH (physical random access channel) setting and information on a PRACH setting for PRACH adaptation to a terminal; a step of confirming that an initial PRACH has not been received from the terminal, wherein the initial PRACH is based on the default PRACH setting or the PRACH setting for PRACH adaptation; and a step of receiving a PRACH retransmitted from the terminal, wherein a PRACH occasion at which the retransmitted PRACH is received corresponds to a PRACH occasion closer in a time domain among the PRACH occasion related to the default PRACH setting or the PRACH occasion related to the PRACH setting for PRACH adaptation at a time point at which PRACH retransmission should be performed.

[0012] In addition, in a terminal of a communication system, the terminal comprises: at least one transceiver; at least one processor communicatively connected to the at least one transceiver; and a memory communicatively connected to the at least one processor and executable individually or in any combination of the at least one processor, the memory storing instructions that cause the terminal to receive information on a default PRACH (physical random access channel) configuration and information on a PRACH configuration for PRACH adaptation from a base station, perform an initial PRACH transmission based on the default PRACH configuration or the PRACH configuration for PRACH adaptation, confirm that a response corresponding to the initial PRACH transmission is not received within a time window, and determine transmission power for PRACH retransmission; and the step of performing the PRACH retransmission at a PRACH occasion closer in the time domain among a PRACH occasion related to the default PRACH configuration or a PRACH occasion related to the PRACH configuration for PRACH adaptation at a time point when the PRACH retransmission should be performed based on the transmission power is characterized by comprising: performing the PRACH retransmission at a PRACH occasion closer in the time domain among the PRACH occasion related to the default PRACH configuration or the PRACH occasion related to the PRACH configuration for PRACH adaptation.

[0013] In addition, in a base station of a communication system, at least one transceiver; at least one processor communicatively connected to the at least one transceiver; and a memory communicatively connected to the at least one processor and executable individually or in any combination of the at least one processor, wherein the base station transmits information on a default PRACH (physical random access channel) configuration and information on a PRACH configuration for PRACH adaptation to a terminal, and confirms that an initial PRACH has not been received from the terminal, wherein the initial PRACH is based on the default PRACH configuration or the PRACH configuration for PRACH adaptation, and stores a command to receive a PRACH retransmitted from the terminal; and a PRACH occasion at which the retransmitted PRACH is received is characterized in that it corresponds to a PRACH occasion closer in a time domain among the PRACH occasion related to the default PRACH configuration or the PRACH occasion related to the PRACH configuration for PRACH adaptation at a time point at which PRACH retransmission should be performed.

[0014] The various embodiments of the present disclosure described above are only 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 a person having ordinary skill in the art based on the detailed description to be described below.

[0015] According to one embodiment of the present disclosure, in a communication system, unnecessary energy consumption of a base station can be reduced by receiving signals and channels (e.g., PRACH) that are conventionally received periodically only when necessary through PRACH adaptation of a base station.

[0016] According to one embodiment of the present disclosure, a PRACH adaptation operation of a base station for energy saving of the base station and a corresponding terminal operation can be provided.

[0017] The effects that can be obtained from the present disclosure are not limited to the effects mentioned above, and other effects that are not mentioned can be clearly understood by a person having ordinary skill in the art to which the present disclosure belongs from the description below.

[0018] FIG. 1 is a diagram illustrating a basic structure of a time-frequency domain, which is a wireless resource domain, in a wireless communication system according to one embodiment of the present disclosure.

[0019] FIG. 2 is a diagram illustrating a slot structure considered in a wireless communication system according to one embodiment of the present disclosure.

[0020] FIG. 3 is a diagram illustrating an example of a time domain mapping structure and beam sweeping operation of a synchronization signal according to one embodiment of the present disclosure.

[0021] FIG. 4 is a diagram illustrating a synchronization signal block considered in a wireless communication system according to one embodiment of the present disclosure.

[0022] FIG. 5 is a diagram illustrating various transmission cases of a synchronization signal block in a frequency band below 6 GHz considered in a wireless communication system according to one embodiment of the present disclosure.

[0023] FIG. 6 is a diagram illustrating transmission cases of a synchronization signal block in a frequency band of 6 GHz or higher considered in a wireless communication system according to one embodiment of the present disclosure.

[0024] FIG. 7 is a diagram illustrating transmission cases of a synchronization signal block according to a subcarrier interval within 5 ms in a wireless communication system according to an embodiment of the present disclosure.

[0025] FIG. 8 is a diagram illustrating an example of a method for resetting SSB transmission through dynamic signaling in a wireless communication system according to one embodiment of the present disclosure.

[0026] FIG. 9 is a diagram illustrating an example of a method for resetting BWP and BW through dynamic signaling in a wireless communication system according to one embodiment of the present disclosure.

[0027] FIG. 10 is a diagram illustrating an example of a method for resetting DRX through dynamic signaling in a wireless communication system according to one embodiment of the present disclosure.

[0028] FIG. 11 is a diagram illustrating an example of a DTx method for base station energy saving according to one embodiment of the present disclosure.

[0029] FIG. 12 is a diagram illustrating an example of the operation of a base station according to gNB WUS according to one embodiment of the present disclosure.

[0030] FIG. 13 is a diagram illustrating a method for adapting an antenna of a base station for energy saving in a wireless communication system according to one embodiment of the present disclosure.

[0031] FIG. 14a is a diagram illustrating an example of a PRACH adaptation operation of a base station according to one embodiment of the present disclosure.

[0032] FIG. 14b is a diagram illustrating another example of a PRACH adaptation operation of a base station according to an embodiment of the present disclosure.

[0033] FIG. 15 is a diagram illustrating an example of a PRACH adaptation operation of a base station according to one embodiment of the present disclosure.

[0034] FIG. 16 is a diagram illustrating another example of a PRACH ramping-up operation of a base station and a terminal according to one embodiment of the present disclosure.

[0035] FIG. 17 is a diagram illustrating another example of a PRACH ramping-up operation of a base station and a terminal according to one embodiment of the present disclosure.

[0036] FIG. 18 is a diagram illustrating another example of a PRACH ramping-up operation of a base station and a terminal according to one embodiment of the present disclosure.

[0037] FIG. 19 is a flowchart of the operation of a terminal applying an energy saving method of a wireless communication system according to one embodiment of the present disclosure.

[0038] FIG. 20 is a flowchart of the operation of a base station applying an energy saving method of a wireless communication system according to one embodiment of the present disclosure.

[0039] FIG. 21 is a block diagram of a terminal according to one embodiment of the present disclosure.

[0040] Figure 22 is a block diagram of a base station according to one embodiment.

[0041] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the attached drawings.

[0042] In describing embodiments of the present disclosure below, descriptions of technical details that are well known in the technical field of the present disclosure and are not directly related to the present disclosure will be omitted. This is to avoid obscuring the gist of the present disclosure by omitting unnecessary explanations and to convey the gist more clearly.

[0043] For the same reason, some components in the attached drawings are exaggerated, omitted, or schematically depicted. Furthermore, the dimensions of each component do not entirely reflect its actual size. Identical or corresponding components in each drawing are assigned the same reference numbers.

[0044] The advantages and features of the present disclosure, and methods for achieving them, will become clearer with reference to the embodiments described below in detail together with the accompanying drawings. However, the present disclosure is not limited to the embodiments described below and may be implemented in various different forms. These embodiments are provided only to make the present disclosure complete and to fully inform those skilled in the art of the present disclosure of the scope of the technical idea, and the present disclosure is defined only by the scope of the claims. Like reference numerals refer to like elements throughout the specification. In addition, the terms described below are terms defined in consideration of the functions in the present disclosure and may vary depending on the intention or custom of the user or operator. Therefore, the definitions should be made based on the contents throughout the specification.

[0045] Hereinafter, the base station is an entity that performs resource allocation of a terminal, and may be at least one of a gNode B, an eNode B, a Node B, a BS (Base Station), a wireless access unit, a base station controller, or a node on a network. The terminal may include a UE (user equipment), an MS (mobile station), a cellular phone, a smartphone, a computer, or a multimedia system capable of performing a communication function. In the present disclosure, the downlink (DL) refers to a wireless transmission path of a signal transmitted from a base station to a terminal, and the uplink (UL) refers to a wireless transmission path of a signal transmitted from a terminal to a base station.

[0046] Furthermore, while the LTE or LTE-A system may be described below as an example, embodiments of the present disclosure may also be applied to other communication systems with similar technical backgrounds or channel types. For example, this may include the fifth-generation mobile communication technology (5G, new radio, NR) developed after LTE-A, and the term "5G" below may also encompass existing LTE, LTE-A, and other similar services. Furthermore, the present disclosure may be applied to other communication systems with some modifications within the scope of the present disclosure, as determined by a person with skilled technical knowledge.

[0047] At this time, it will be understood that each block of the processing flowchart drawings and combinations of the flowchart drawings can be performed by computer program instructions. These computer program instructions can be installed in a processor of a general-purpose computer, a special-purpose computer, or other programmable data processing equipment, so that the instructions executed by the processor of the computer or other programmable data processing equipment create a means for performing the functions described in the flowchart block(s). These computer program instructions can also be stored in a computer-available or computer-readable memory that can direct a computer or other programmable data processing equipment to implement the functions in a specific manner, so that the instructions stored in the computer-available or computer-readable memory can also produce a manufactured item that includes an instruction means for performing the functions described in the flowchart block(s). Since the computer program instructions may be installed on a computer or other programmable data processing device, a series of operational steps may be performed on the computer or other programmable data processing device to create a computer-executable process, and the instructions that cause the computer or other programmable data processing device to perform the steps for performing the functions described in the flowchart block(s) may also provide steps for performing the functions described in the flowchart block(s).

[0048] Additionally, each block may represent a module, segment, or portion of code that contains one or more executable instructions for performing a specific logical function(s). It should also be noted that in some alternative implementation examples, the functions described in the blocks may occur out of order. For example, two blocks depicted in succession may actually be executed substantially concurrently, or the blocks may sometimes be executed in reverse order, depending on their respective functions.

[0049] The term '~ unit' used in this disclosure means a software or hardware component such as a Field Programmable Gate Array (FPGA) or an Application Specific Integrated Circuit (ASIC), and the '~ unit' performs certain roles. However, the '~ unit' is not limited to software or hardware. The '~ unit' may be configured to be on an addressable storage medium and may be configured to play one or more processors. Thus, as an example, the '~ unit' includes components such as software components, object-oriented software components, class components, and task components, processes, functions, attributes, procedures, subroutines, segments of program code, drivers, firmware, microcode, circuits, data, databases, data structures, tables, arrays, and variables. The functionality provided within the components and '~ units' may be combined into a smaller number of components and '~ units' or further separated into additional components and '~ units'. Additionally, the components and '~parts' may be implemented to activate one or more CPUs within a device or secure multimedia card. In addition, in an embodiment, the '~parts' may include one or more processors.

[0050] The methods and devices proposed in the embodiments of the present disclosure are not limited to each embodiment, and may be utilized as a combination of one or more embodiments, all or part of the embodiments proposed in the disclosure. Accordingly, the embodiments of the present disclosure may be applied with some modifications within a scope that does not significantly deviate from the scope of the present disclosure, as determined by a person skilled in the art.

[0051] Wireless communication systems are evolving from providing voice-oriented services in the early days to broadband wireless communication systems that provide high-speed, high-quality packet data services, such as 3GPP's HSPA (high speed packet access), LTE (long term evolution or E-UTRA (evolved universal terrestrial radio access)), LTE-Advanced (LTE-A), LTE-Pro, 3GPP2's HRPD (high rate packet data), UMB (ultra mobile broadband), and IEEE's 802.17e communication standards.

[0052] In the LTE system, which is a representative example of a broadband wireless communication system, the downlink (DL) adopts the orthogonal frequency division multiplexing (OFDM) method, and the uplink (UL) adopts the single carrier frequency division multiple access (SC-FDMA) method. The uplink refers to a wireless link in which a terminal (hereinafter referred to as user equipment (UE)) (or mobile station (MS)) transmits data or control signals to a base station (eNode B (eNB) or base station (BS)), and the downlink refers to a wireless link in which a base station transmits data or control signals to a terminal (UE). In addition, the aforementioned multiple access method typically allocates and operates time-frequency resources for transmitting data or control information to each user so that they do not overlap, that is, so as to achieve orthogonality, thereby distinguishing the data or control information of each user.

[0053] 5G communication systems, the successor to LTE, must support services that simultaneously satisfy diverse requirements, allowing them to freely reflect the diverse needs of users and service providers. Services being considered for 5G communication systems include enhanced mobile broadband (eMBB), massive machine type communication (mMTC), and ultra-reliable low-latency communication (URLLC).

[0054] eMBB aims to provide data transmission rates that are significantly higher than those supported by existing LTE, LTE-A, or LTE-Pro. For example, in a 5G communication system, eMBB must be able to provide a peak data rate of 20 Gbps in the downlink and a peak data rate of 10 Gbps in the uplink from the perspective of a single base station. Furthermore, 5G communication systems must provide not only the peak data rate but also the increased user-perceived data rate for terminals. To meet these requirements, improvements in various transmission and reception technologies, including improved multi-input, multi-output (MIMO) transmission technology, may be required. Furthermore, while LTE systems transmit signals using a maximum transmission bandwidth of 20 MHz in the 2 GHz band, 5G communication systems can meet the data transmission rates required by 5G communication systems by using a wider frequency bandwidth than 20 MHz in the 3 to 6 GHz or higher frequency bands.

[0055] At the same time, mMTC is being considered to support application services such as the Internet of Things (IoT) in 5G communication systems. To efficiently provide the Internet of Things, mMTC requires supporting a large number of terminals within a cell, improving terminal coverage, extending battery life, and reducing terminal costs. The Internet of Things provides communication functions by attaching various sensors and various devices, so a large number of terminals (e.g., 1,000,000 terminals / km) are required within a cell. 2 ) must be able to support. Furthermore, terminals supporting mMTC are likely to be located in shadow areas not covered by cells, such as basements of buildings, due to the nature of the service, requiring wider coverage than other services provided by 5G communication systems. Terminals supporting mMTC must be composed of low-cost terminals, and since it is difficult to frequently replace the terminal's battery, they require a very long battery life time, such as 10 to 16 years.

[0056] Finally, URLLC refers to a cellular-based wireless communication service used for a specific purpose (mission-critical). For example, services can be considered for remote control of robots or machinery, industrial automation, unmanaged aerial vehicles, remote health care, or emergency alerts. Therefore, the communication provided by URLLC must provide very low latency and very high reliability. For example, a service supporting URLLC must satisfy an air interface latency of less than 0.5 milliseconds and, at the same time, must have a 10 -5The following packet error rate requirements must be met. Therefore, for services supporting URLLC, 5G systems must provide a smaller transmit time interval (TTI) than other services, while simultaneously allocating extensive resources in the frequency band to ensure communication link reliability.

[0057] The three services of the 5G communication system (hereinafter, "interoperable with 5G systems")—eMBB, URLLC, and mMTC—can be multiplexed and transmitted within a single system. To meet the different requirements of each service, different transmission and reception techniques and parameters can be used across the services.

[0058] The frame structure of the 5G system will be described in more detail below with reference to the drawings. For convenience of explanation, the wireless communication system to which the present disclosure applies will be described below using the configuration of a 5G system as an example. However, the embodiments of the present disclosure can be applied in the same or similar manner to systems beyond 5G or other communication systems to which the present disclosure applies.

[0059] FIG. 1 is a diagram illustrating a basic structure of a time-frequency domain, which is a wireless resource domain, in a wireless communication system according to one embodiment of the present disclosure.

[0060] In Fig. 1, the horizontal axis represents the time domain, and the vertical axis represents the frequency domain. The basic unit of resources in the time and frequency domains is a resource element (RE, 101), which can be defined as one OFDM symbol (or DFT-s-OFDM (discrete Fourier transform spread OFDM) symbol) (102) in the time axis and one subcarrier (subcarrier, 103) in the frequency axis. In the frequency domain, the number of subcarriers per resource block (RB) is represented by (For example, 12) consecutive REs can form one resource block (RB, 104). In addition, the number of symbols per subframe according to the setting value μ for the subcarrier spacing in the time domain is indicated. A number of consecutive OFDM symbols can constitute one subframe (subframe, 110).

[0061] FIG. 2 is a diagram illustrating a slot structure considered in a wireless communication system according to one embodiment of the present disclosure.

[0062] FIG. 2 illustrates an example of a slot structure including a frame (200), a subframe (201), and slots (202, 203). One frame (200) can be defined as 10 ms. One subframe (201) can be defined as 1 ms, and thus one frame (200) can be composed of a total of 10 subframes (201). One slot (202, 203) can be defined as 14 OFDM symbols (i.e., the number of symbols per slot ( ))=14). One subframe (201) may be composed of one or more slots (202, 203), and the number of slots (202, 203) per one subframe (201) may vary depending on μ (204 or 205), which is a setting value for the subcarrier space (SCS).

[0063] The slot structure is illustrated when μ=0 (204) and μ=1 (205) as the subcarrier spacing setting value. When μ=0 (204), one subframe (201) can be composed of one slot (202), and when μ=1 (205), one subframe (201) can be composed of two slots (including slot (203) for example). That is, depending on the setting value μ for the subcarrier spacing, the number of slots per subframe ( )) may vary, and accordingly the number of slots per frame ( ) may vary. For example, depending on the subcarrier spacing setting μ and can be defined as shown in Table 1 below.

[0064] μ 0141011142022144043148084141601651432032

[0065] In a 5G wireless communication system, a synchronization signal block (SSB, which may be used interchangeably with an SS block or an SS / PBCH block) may be transmitted for initial connection of a terminal, and the synchronization signal block may include a primary synchronization signal (PSS), a secondary synchronization signal (SSS), and a physical broadcast channel (PBCH).

[0066] In the initial access phase where a terminal connects to the system, the terminal can first acquire downlink time and frequency domain synchronization from a synchronization signal through cell search and acquire a cell ID. The synchronization signal may include PSS and SSS. In addition, the terminal can obtain transmission-related system information and basic parameter values, such as system bandwidth or related control information, by receiving a PBCH that transmits a master information block (MIB) from the base station. Based on this information, the terminal can perform decoding on the physical downlink control channel (PDCCH) and the physical downlink shared channel (PDSCH) to acquire a system information block (SIB). Thereafter, the terminal can exchange identification-related information with the base station through a random access phase and go through registration and authentication phases to initially access the network. Additionally, the terminal can obtain cell-common transmission-related control information by receiving system information (SIB) transmitted by the base station. The above cell common transmission and reception related control information may include random access related control information, paging related control information, common control information for various physical channels, etc.

[0067] The synchronization signal serves as a reference signal for cell search, and an appropriate subcarrier spacing can be applied to suit channel conditions such as phase noise for each frequency band. For data channels or control channels, as described above, different subcarrier spacings can be applied depending on the service type to support various services.

[0068] FIG. 3 is a diagram illustrating an example of a time domain mapping structure and beam sweeping operation of a synchronization signal according to one embodiment of the present disclosure.

[0069] For illustrative purposes, the following components can be defined:

[0070] - PSS: A signal that serves as a reference for DL ​​time / frequency synchronization and provides some cell ID information.

[0071] - SSS: It serves as a reference for DL ​​time / frequency synchronization and provides some remaining information, including the cell ID. Additionally, it can serve as a reference signal (RS) for PBCH demodulation.

[0072] - PBCH: Provides MIB, which is essential system information required for transmission and reception of data channels and control channels of the terminal. The essential system information may include search space-related control information indicating radio resource mapping information of the control channel, scheduling control information for a separate data channel that transmits system information, and SFN (system frame number), which is a frame-unit index that serves as a timing reference.

[0073] - SS / PBCH block: An SS / PBCH block consists of N OFDM symbols and is a combination of PSS, SSS, PBCH, etc. In a system where beam sweeping technology is applied, the SS / PBCH block is the minimum unit to which beam sweeping is applied. In a 5G system, N can be 4. The base station can transmit up to L SS / PBCH blocks, and the L SS / PBCH blocks are mapped within a half frame (0.5 ms). In addition, the L SS / PBCH blocks are periodically repeated in units of a predetermined period P. The period P can be notified to the terminal by the base station through signaling. If there is no separate signaling for the period P, the terminal applies a pre-agreed default value.

[0074] Referring to FIG. 3, beam sweeping can be applied to SS / PBCH block units over time. Terminal 1 (305) receives an SS / PBCH block using a beam radiated in the direction of #d0 (303) by beamforming applied to SS / PBCH block #0 at time t1 (301). Terminal 2 (306) receives an SS / PBCH block using a beam radiated in the direction of #d4 (304) by beamforming applied to SS / PBCH block #4 at time t2 (302). The terminal can obtain an optimal synchronization signal through a beam radiated from the base station in the direction where the terminal is located. For example, it may be difficult for terminal 1 (305) to obtain time / frequency synchronization and essential system information from an SS / PBCH block through a beam radiated in the direction of #d4, which is far from the location of terminal 1.

[0075] In addition to the initial connection procedure, the UE may also receive SS / PBCH blocks to determine whether the radio link quality of the current cell is maintained at a certain level. Furthermore, during a handover procedure, in which the UE moves from the current cell to a neighboring cell, the UE may receive SS / PBCH blocks from the neighboring cell to determine the radio link quality of the neighboring cell and obtain time / frequency synchronization with the neighboring cell.

[0076] Below, the cell initial access operation procedure of a 5G wireless communication system will be described in more detail with reference to drawings.

[0077] A 5G base station can transmit multiple synchronization signal blocks, depending on the number of analog beams it intends to operate. For example, PSS and SSS can be mapped and transmitted across 12 RBs, while PBCH can be mapped and transmitted across 24 RBs. The following describes the structure for transmitting synchronization signals and PBCH in a 5G communication system.

[0078] FIG. 4 is a diagram illustrating a synchronization signal block considered in a wireless communication system according to one embodiment of the present disclosure.

[0079] Referring to FIG. 4, a synchronization signal block (SS block) (400) may include a PSS (401), an SSS (403), and a Physical Broadcast Channel (PBCH) (402). The synchronization signal block (400) may be mapped to four OFDM symbols (404) in the time axis. The PSS (401) and the SSS (403) may be transmitted in 12 RBs (405) in the frequency axis and in the first and third OFDM symbols in the time axis, respectively. In a 5G system, for example, a total of 1008 different cell IDs may be defined. Depending on the physical cell ID (PCI) of the cell, the PSS (401) may have three different values, and the SSS (403) may have 336 different values. The terminal can obtain one of (336X3=)1008 cell IDs by detecting the PSS (401) and SSS (403) and combining them. This can be expressed by the following mathematical expression 1.

[0080] [Mathematical Formula 1]

[0081]

[0082] Here can be estimated from SSS(403) and can have a value between 0 and 335. can be estimated from PSS (401) and can have a value between 0 and 2. The terminal class Cell ID is a combination of The value can be estimated.

[0083] PBCH (402) can be transmitted in resources including 6 RBs (407, 408) on both sides, excluding 12 RBs (405) in the middle, while SSS (403) is transmitted in 24 RBs (406) in the frequency axis and in the 2nd to 4th OFDM symbols of the SS block in the time axis. PBCH (402) can include a PBCH payload and a PBCH DMRS (demodulation reference signal), and various system information called MIB can be transmitted in the PBCH payload. For example, MIB can include information as shown in Table 2 below.

[0084] MIB ::= SEQUENCE {systemFrameNumber BIT STRING (SIZE (6)),subCarrierSpacingCommon ENUMERATED {scs15or60, scs30or120},ssb-SubcarrierOffset INTEGER (0..15),dmrs-TypeA-Position ENUMERATED {pos2, pos3},pdcch-ConfigSIB1 PDCCH-ConfigSIB1,cellBarred ENUMERATED {barred, notBarred},intraFreqReselection ENUMERATED {allowed, notAllowed},spare BIT STRING (SIZE (1))}

[0085] - Synchronization signal block information: The frequency domain offset of the synchronization signal block can be indicated through the 4-bit ssb-SubcarrierOffset in the MIB. The index of the synchronization signal block including the PBCH can be indirectly obtained through decoding the PBCH DMRS and the PBCH. In one embodiment, in a frequency band below 6 GHz, 3 bits obtained through decoding the PBCH DMRS indicate the synchronization signal block index, and in a frequency band above 6 GHz, a total of 6 bits, including 3 bits obtained through decoding the PBCH DMRS and 3 bits obtained through decoding the PBCH included in the PBCH payload, can indicate the synchronization signal block index including the PBCH.

[0086] - PDCCH configuration information: The subcarrier spacing of the common downlink control channel can be indicated through 1 bit (subCarrierSpacingCommon) in the MIB, and the time-frequency resource configuration information of the CORESET (control resource set) and search space can be indicated through 8 bits (pdcch-ConfigSIB1).

[0087] - SFN (system frame number): 6 bits (systemFrameNumber) within the MIB can be used to indicate a portion of the SFN. The 4 least significant bits (LSBs) of the SFN are included in the PBCH payload, so the terminal can indirectly obtain them through PBCH decoding.

[0088] - Timing information within a radio frame: The terminal can indirectly determine whether the synchronization signal block was transmitted in the first or second half frame of the radio frame by using the synchronization signal block index described above and 1 bit (half frame) obtained through PBCH decoding included in the PBCH payload.

[0089] Since the transmission bandwidths (12 RB (405)) of PSS (401) and SSS (403) and the transmission bandwidth (24 RB (406)) of PBCH (402) are different from each other, in the first OFDM symbol in which PSS (401) is transmitted within the transmission bandwidth of PBCH (402), 6 RBs (407, 408) on both sides exist except for the 12 RBs in the middle in which PSS (401) is transmitted, and the above areas can be used to transmit other signals or can be empty.

[0090] Synchronization signal blocks can be transmitted using the same analog beam. For example, PSS (401), SSS (403), and PBCH (402) can all be transmitted using the same beam. Since analog beams have the characteristic that they cannot be applied differently in the frequency axis, the same analog beam can be applied to all frequency axis RBs within a specific OFDM symbol to which a specific analog beam is applied. For example, all four OFDM symbols in which PSS (401), SSS (403), and PBCH (402) are transmitted can be transmitted using the same analog beam.

[0091] FIG. 5 is a diagram illustrating various transmission cases of a synchronization signal block in a frequency band below 6 GHz considered in a wireless communication system according to one embodiment of the present disclosure.

[0092] Referring to FIG. 5, in a 5G communication system, in a frequency band below 6 GHz (or FR1 (frequency range 1), for example, 410 MHz-7125 MHz), a 15 kHz subcarrier spacing (SCS) (520) and a 30 kHz subcarrier spacing (SCS) (530, 540) may be used for transmission of a synchronization signal block. In the 15 kHz subcarrier spacing (520), there may be one transmission case (e.g., case #1 (501)) for the synchronization signal block, and in the 30 kHz subcarrier spacing (530, 540), there may be two transmission cases (e.g., case #2 (502) and case #3 (503)) for the synchronization signal block.

[0093] In case #1 (501) at the subcarrier spacing of 15 kHz (520) in FIG. 5, a maximum of two synchronization signal blocks can be transmitted within 1 ms (504) (or equivalent to 1 slot length when 1 slot consists of 14 OFDM symbols). In the example of FIG. 4, synchronization signal block #0 (507) and synchronization signal block #1 (508) are illustrated. For example, synchronization signal block #0 (507) can be mapped to 4 consecutive symbols from the 3rd OFDM symbol, and synchronization signal block #1 (508) can be mapped to 4 consecutive symbols from the 9th OFDM symbol.

[0094] Different analog beams can be applied to synchronization signal block #0 (507) and synchronization signal block #1 (508). The same beam can be applied to all 3rd to 6th OFDM symbols to which synchronization signal block #0 (507) is mapped, and the same beam can be applied to all 9th ​​to 12th OFDM symbols to which synchronization signal block #1 (508) is mapped. In the 7th, 8th, 13th, and 14th OFDM symbols to which synchronization signal blocks are not mapped, the analog beam can be freely determined at the discretion of the base station as to which beam to use.

[0095] In case #2 (502) at subcarrier spacing of 30 kHz (530) in FIG. 5, a maximum of two synchronization signal blocks can be transmitted within 0.5 ms (505) (or 1 slot length when 1 slot consists of 14 OFDM symbols), and accordingly, a maximum of four synchronization signal blocks can be transmitted within 1 ms (or 2 slot lengths when 1 slot consists of 14 OFDM symbols). In one example of FIG. 4, a case is illustrated where synchronization signal block #0 (509), synchronization signal block #1 (510), synchronization signal block #2 (511), and synchronization signal block #3 (512) are transmitted within 1 ms (i.e., two slots) of time. Synchronization signal block #0 (509) and synchronization signal block #1 (510) can be mapped from the 5th OFDM symbol and the 9th OFDM symbol of the first slot, respectively, and synchronization signal block #2 (511) and synchronization signal block #3 (512) can be mapped from the 3rd OFDM symbol and the 7th OFDM symbol of the second slot, respectively.

[0096] Different analog beams may be applied to synchronization signal block #0 (509), synchronization signal block #1 (510), synchronization signal block #2 (511), and synchronization signal block #3 (512), respectively. In addition, the same analog beam may be applied to the 5th to 8th OFDM symbols of the first slot in which synchronization signal block #0 (509) is transmitted, the 9th to 12th OFDM symbols of the first slot in which synchronization signal block #1 (510) is transmitted, the 3rd to 6th symbols of the second slot in which synchronization signal block #2 (511) is transmitted, and the 7th to 10th symbols of the second slot in which synchronization signal block #3 (512) is transmitted. In OFDM symbols in which synchronization signal blocks are not mapped, the analog beam may be freely determined at the discretion of the base station as to which beam to use.

[0097] In case #3 (503) at subcarrier spacing of 30 kHz (540) in FIG. 5, a maximum of two synchronization signal blocks can be transmitted within 0.5 ms (506) (or 1 slot length when 1 slot consists of 14 OFDM symbols), and accordingly, a maximum of four synchronization signal blocks can be transmitted within 1 ms (or 2 slot lengths when 1 slot consists of 14 OFDM symbols). In one example of FIG. 4, synchronization signal block #0 (513), synchronization signal block #1 (514), synchronization signal block #2 (515), and synchronization signal block #3 (516) are illustrated as being transmitted within 1 ms (i.e., two slots) of time. Synchronization signal block #0 (513) and synchronization signal block #1 (514) can be mapped from the 3rd OFDM symbol and the 9th OFDM symbol of the first slot, respectively, and synchronization signal block #2 (515) and synchronization signal block #3 (516) can be mapped from the 3rd OFDM symbol and the 9th OFDM symbol of the second slot, respectively.

[0098] Different analog beams may be used for synchronization signal block #0 (513), synchronization signal block #1 (514), synchronization signal block #2 (515), and synchronization signal block #3 (516), respectively. As described in the examples above, the same analog beam may be used in all four OFDM symbols in which each synchronization signal block is transmitted, and the base station may freely determine which beam to use in OFDM symbols to which no synchronization signal block is mapped.

[0099] FIG. 6 is a diagram illustrating transmission cases of a synchronization signal block in a frequency band of 6 GHz or higher considered in a wireless communication system according to one embodiment of the present disclosure.

[0100] Referring to FIG. 6, in a wireless communication system, in a frequency band of 6 GHz or higher (or FR2, for example, 24250 MHz-52000 MHz), a subcarrier spacing of 120 kHz (630) as in the example of Case #4 (610) and a subcarrier spacing of 240 kHz (640) as in the example of Case #5 (620) may be used for transmission of a synchronization signal block.

[0101] In case #4 (610) with a subcarrier spacing of 120 kHz (630), up to four synchronization signal blocks can be transmitted within a time period of 0.25 ms (601) (or equivalent to two slot lengths when one slot consists of 14 OFDM symbols). In the example of Fig. 6, synchronization signal block #0 (603), synchronization signal block #1 (604), synchronization signal block #2 (605), and synchronization signal block #3 (606) are illustrated as being transmitted within 0.25 ms (i.e., two slots). Synchronization signal block #0 (603) and synchronization signal block #1 (604) can be mapped to 4 consecutive symbols starting from the 5th OFDM symbol of the first slot, and to 4 consecutive symbols starting from the 9th OFDM symbol, respectively, and synchronization signal block #2 (605) and synchronization signal block #3 (606) can be mapped to 4 consecutive symbols starting from the 3rd OFDM symbol of the second slot, and to 4 consecutive symbols starting from the 7th OFDM symbol, respectively.

[0102] As described in the above embodiment, different analog beams may be used for synchronization signal block #0 (603), synchronization signal block #1 (604), synchronization signal block #2 (605), and synchronization signal block #3 (606), respectively. In addition, the same analog beam may be used in all four OFDM symbols in which each synchronization signal block is transmitted, and in OFDM symbols to which no synchronization signal block is mapped, the beam to be used may be freely determined at the discretion of the base station.

[0103] In case #5 (620) at subcarrier spacing of 240 kHz (640), up to 8 synchronization signal blocks can be transmitted within 0.25 ms (602) (or 4 slot length when 1 slot consists of 14 OFDM symbols). In the example of Fig. 6, synchronization signal block #0 (607), synchronization signal block #1 (608), synchronization signal block #2 (609), synchronization signal block #3 (610), synchronization signal block #4 (611), synchronization signal block #5 (612), synchronization signal block #6 (613), and synchronization signal block #7 (614) are illustrated as being transmitted within 0.25 ms (i.e. 4 slots).

[0104] Synchronization signal block #0 (607) and synchronization signal block #1 (608) can be mapped to 4 consecutive symbols from the 9th OFDM symbol of the first slot, and 4 consecutive symbols from the 13th OFDM symbol, respectively; synchronization signal block #2 (609) and synchronization signal block #3 (610) can be mapped to 4 consecutive symbols from the 3rd OFDM symbol of the second slot, and 4 consecutive symbols from the 7th OFDM symbol, respectively; synchronization signal block #4 (611), synchronization signal block #5 (612), and synchronization signal block #6 (613) can be mapped to 4 consecutive symbols from the 5th OFDM symbol of the third slot, and 4 consecutive symbols from the 9th OFDM symbol, and 4 consecutive symbols from the 13th OFDM symbol, respectively; synchronization signal block #7 (614) can be mapped to 4 consecutive symbols from the 4th slot, and 4 consecutive symbols from the 9th OFDM symbol, respectively; It can be mapped to four consecutive symbols starting from the third OFDM symbol.

[0105] As described in the above embodiment, different analog beams may be used for synchronization signal block #0 (607), synchronization signal block #1 (608), synchronization signal block #2 (609), synchronization signal block #3 (610), synchronization signal block #4 (611), synchronization signal block #5 (612), synchronization signal block #6 (613), and synchronization signal block #7 (614), respectively. In addition, the same analog beam may be used in all four OFDM symbols in which each synchronization signal block is transmitted, and in OFDM symbols to which the synchronization signal block is not mapped, which beam to be used may be freely determined at the discretion of the base station.

[0106] FIG. 7 is a diagram illustrating transmission cases of a synchronization signal block according to a subcarrier interval within 5 ms in a wireless communication system according to an embodiment of the present disclosure.

[0107] Referring to FIG. 7, in a 5G communication system, a synchronization signal block may be periodically transmitted in units of, for example, a time interval (710) of 5 ms (corresponding to 5 subframes or half frames).

[0108] In frequency bands below 3 GHz, up to four synchronization signal blocks can be transmitted within a 5 ms (710) period. In frequency bands exceeding 3 GHz and below 6 GHz, up to eight synchronization signal blocks can be transmitted. In frequency bands above 6 GHz, up to 64 synchronization signal blocks can be transmitted. As described above, subcarrier spacings of 15 kHz and 30 kHz can be used in frequencies below 6 GHz.

[0109] In the example of FIG. 7, in case #1 (501) of FIG. 5, which consists of one slot and has a subcarrier spacing of 15 kHz, synchronization signal blocks can be mapped to the first and second slots in a frequency band of 3 GHz or less, so that up to 4 (721) can be transmitted, and in the frequency band of more than 3 GHz and less than 6 GHz, synchronization signal blocks can be mapped to the first, second, third, and fourth slots, so that up to 8 (722) can be transmitted. In case #2 (502) or case #3 (503) with a subcarrier spacing of 30 kHz and consisting of two slots of FIG. 5, synchronization signal blocks can be mapped starting from the first slot in a frequency band of 3 GHz or less, so that up to 4 (731, 741) can be transmitted, and in a frequency band exceeding 3 GHz and below 6 GHz, synchronization signal blocks can be mapped starting from the first and third slots, so that up to 8 (732, 742) can be transmitted.

[0110] Subcarrier spacings of 120 kHz and 240 kHz can be used in frequencies exceeding 6 GHz. In the example of Fig. 7, in case #4 (610) with subcarrier spacing of 120 kHz consisting of two slots of Fig. 6, synchronization signal blocks in the frequency band exceeding 6 GHz can be mapped starting from the 1st, 3rd, 5th, 7th, 11th, 13th, 15th, 17th, 21st, 23rd, 25th, 27th, 31st, 33rd, 35th, and 37th slots, so that up to 64 (751) can be transmitted. In the example of FIG. 7, in case #5 (620) of FIG. 6, which consists of four slots and a subcarrier spacing of 240 kHz, synchronization signal blocks in a frequency band exceeding 6 GHz can be mapped starting from the 1st, 5th, 9th, 13th, 21st, 25th, 29th, and 33rd slots, so that up to 64 (761) can be transmitted.

[0111] The terminal can decode the PDCCH and PDSCH based on the system information included in the received MIB and then acquire the SIB. The SIB may include at least one of uplink cell bandwidth-related information, random access parameters, paging parameters, or parameters related to uplink power control.

[0112] Typically, a terminal can establish a wireless link with a network through a random access procedure based on synchronization with the network and system information acquired during the cell search process. Random access can be either contention-based or contention-free. When a terminal performs cell selection and reselection during the initial cell access phase, for example, contention-based random access can be used to transition from the RRC_IDLE state to the RRC_CONNECTED state. Contention-free random access can be used to reestablish uplink synchronization when downlink data arrives, in the case of a handover, or for positioning. Table 3 below illustrates the conditions (events) that trigger a random access procedure in a 5G system.

[0113] - Initial access from RRC_IDLE;- RRC Connection Re-establishment procedure;- DL or UL data arrival during RRC_CONNECTED when UL synchronization status is "non-synchronised";- UL data arrival during RRC_CONNECTED when there are no PUCCH resources for SR available;- SR failure;- Request by RRC upon synchronous reconfiguration (eg handover);- RRC Connection Resume procedure from RRC_INACTIVE;- To establish time alignment for a secondary TAG;- Request for Other SI;- Beam failure recovery;- Consistent UL LBT failure on SpCell.

[0114] Below, we describe a method for reducing SSB density through dynamic signaling to save base station energy in 5G systems.

[0115] FIG. 8 is a diagram illustrating an example of a method for resetting SSB transmission through dynamic signaling in a wireless communication system according to one embodiment of the present disclosure.

[0116] Referring to Fig. 8, the terminal can receive ssb-PositionsInBurst = '11110000' (802) from the base station through upper layer signaling (SIB1 or ServingCellConfigCommon). At the subcarrier spacing of 30 kHz, a maximum of two synchronization signal blocks can be transmitted within 0.5 ms (or 1 slot length when 1 slot consists of 14 OFDM symbols), and accordingly, the terminal can receive 4 synchronization signal blocks within 1 ms (or 2 slot lengths when 1 slot consists of 14 OFDM symbols). At this time, the base station may reset the SSB transmission configuration information by broadcasting the bitmap '1010xxxx' (804) through the group common or / and cell common DCI (hereinafter, group / cell common DCI, 803) having nwes-RNTI (network energy saving-radio network temporary identifier, or es-RNTI) to reduce the density of SSB transmission for energy saving. At this time, the transmission of SS block#1 (805) and SSblock#3 (806) may be canceled based on the bitmap (804) set as the group / cell common DCI. Fig. 8 illustrates a method (801) for resetting SSB transmission through bitmap-based group / cell common DCI.

[0117] In addition, the base station can reset the ssb-periodicity set through upper layer signaling via group / cell common DCI. In addition, timer information for indicating the application time of the group / cell common DCI can be additionally set, and SSB can be transmitted through the SSB transmission information reset by the group / cell common DCI during the set timer. Afterwards, when the timer expires, the base station can operate with the SSB transmission information set by the existing upper layer signaling. In this way, the setting can be changed from normal mode to energy saving mode through the timer, and the SSB configuration information can be reset accordingly. Alternatively, the base station can set the application time and period of the SSB configuration information reset through the group / cell common DCI to the terminal using offset and duration information. In this case, the terminal may not monitor SSB for the duration from the moment when the group / cell common DCI is received to the moment when the offset is applied.

[0118] Below, we describe a BWP or BW adaptation method through dynamic signaling for base station energy saving in 5G systems.

[0119] FIG. 9 is a diagram illustrating an example of a method for resetting BWP and BW through dynamic signaling in a wireless communication system according to one embodiment of the present disclosure.

[0120] Referring to Figure 9, the terminal can operate with BWP or BW activated through upper layer signaling and L1 signaling from the base station (901). For example, the terminal can operate with a fixed power PSD. B It can operate through a full BW of 100MHz. At this time, the base station uses the same power PSD for energy saving. BThe BW and BWP can be adjusted to activate a narrower BW of 40 MHz for the terminal (902). At this time, the BW or BWP adjustment operation for energy saving of the base station can be set to match the BWP and BW settings that are set UE-specifically through the group common DCI and the cell specific DCI (903). For example, UE#0 and UE#1 can have different BWP configurations and locations. At this time, the BW and BWP of all terminals can be set to be the same in order to save energy by reducing the BW used by the base station. At this time, the BWP or BW in the operation for energy saving can be set to one or more, and this can be used to set the BWP for each UE group.

[0121] In describing the present disclosure, upper layer signaling may be signaling corresponding to at least one or a combination of one or more of the following signaling.

[0122] - MIB

[0123] - SIB or SIB X (X=1, 2, 쪋)

[0124] - RRC (radio resource control)

[0125] - MAC (medium access control) CE (control element)

[0126] In addition, L1 signaling may be signaling corresponding to at least one or a combination of one or more signaling methods using the physical layer channel or signaling below.

[0127] - PDCCH

[0128] - DCI (downlink control information)

[0129] - UE-specific DCI

[0130] - Group common DCI

[0131] - Common DCI

[0132] - Scheduling DCI (e.g. DCI used for scheduling downlink or uplink data)

[0133] - Non-scheduled DCI (e.g. DCI not intended for scheduling downlink or uplink data)

[0134] - PUCCH (physical uplink control channel)

[0135] - UCI (uplink control information)

[0136] In the present disclosure below, the above examples are described through multiple embodiments, but they are not independent, and one or more embodiments may be applied simultaneously or in combination.

[0137] Below, a DRX alignment method through dynamic signaling for base station energy saving in a 5G system is described.

[0138] FIG. 10 is a diagram illustrating an example of a method for reconfiguring DRX through dynamic signaling in a wireless communication system according to an embodiment of the present disclosure. Referring to FIG. 10, a base station can configure DRX in a UE-specific manner through higher layer signaling. For example, different drx-LongCycle (1002) or drx-ShortCycle, drx-onDurationTimer (1003), and drx-InactivityTimer (1004) can be configured for each UE. Thereafter, the base station can configure UE-specific DRX settings in a UE group-specific or cell-specific manner through L1 signaling (1001) for energy saving. Through this, the base station can obtain the same effect of saving power as that of a UE through DRX for energy saving.

[0139] Below, we describe the DTx (discontinuous transmission) operation to reduce energy consumption of base stations in 5G systems.

[0140] FIG. 11 is a diagram illustrating an example of a DTx method for base station energy saving according to one embodiment of the present disclosure. Referring to FIG. 11, a base station can configure DTx for energy saving through upper layer signaling (e.g., a new system information block (SIB) for DTx or RRC signaling) and L1 signaling (e.g., DCI). At this time, the base station can set dtx-onDurationTimer (1105) for transmitting a reference signal for measuring PDCCH for scheduling DL SCH for DTx operation, RRM measurement, beam management, and rdufh loss (pathloss), dtx-InactivityTimer (1106) for receiving PDSCH after receiving PDCCH for scheduling DL SCH, dtx-offset (1104) for setting an offset between dtx-onDurationTimer and synchronization signal (1103) for synchronization before dtx-onDurationTimer, and dtx-(Long)Cycle (1102) for DTx to operate periodically based on configuration information. At this time, dtx-cycle can be set to multiple long cycles and short cycles. During the operation of DTx, the base station considers the transmitter to be off (or inactive), and therefore may not transmit DL CCH, SCH, and DL RS. That is, the base station can transmit downlink signals and channels (e.g., PDCCH, PDSCH, reference signals, etc.) only during SS, dtx-onDurationTimer, and dtx-InactivityTimer during the operation of DTx. At this time, SS-gapbetweenBurst (the gap between SS bursts in the time domain) or the number of SS bursts can be additionally configured as additional information of the configured SS.

[0141] Below, a method for activating a base station through a gNB WUS (wake-up signal) during the base station's inactive mode to reduce energy consumption of the base station in a 5G system is described.

[0142] FIG. 12 is a diagram illustrating an example of the operation of a base station according to gNB WUS according to an embodiment of the present disclosure. Referring to FIG. 12, the base station can keep the transmitter off (or inactive) while the base station is in an inactive state (or sleep mode) to save energy. Thereafter, the base station can receive a gNB WUS (1202) from a terminal to activate the sleep mode of the base station. Thereafter, when the base station receives the WUS from the terminal through the Rx terminal, the base station can turn the Tx terminal on (or active) (1203). Thereafter, the base station can perform downlink transmission to the terminal. At this time, the base station can perform synchronization after Tx on and transmit control information and data. In addition, various uplink signals, such as PRACH, SR (scheduling request), PUCCH including ACK, etc., can be considered as gNB WUS. Through the above method, the base station can perform energy saving, and at the same time, the terminal can improve delay.

[0143] At this time, the base station can set a WUS occasion for receiving the gNB WUS and a Sync RS for synchronization before the terminal transmits the gNB WUS. At this time, SSB, TRS (tracking RS), light SSB (PSS+SSS), continuous SSBs, or new RS (continuous PSS and SSS) can be considered as the Sync RS, and PRACH, SR, or a sequence-based signal can be considered as the WUS. The Sync RS (1204) for the terminal to activate the deactivation mode for energy saving of the base station and the WUS occasion for receiving the WUS can be repeatedly transmitted with a WUS-RS cycle (1205). In the case of FIG. 12, one embodiment is described by taking 1-to-1 mapping of the Sync RS and the WUS occasion as an example, but the present disclosure is not limited thereto. For example, Sync and WUS occasions can be N-to-1 mapped, 1-to-N mapped, or N-to-M mapped.

[0144] Below, a method for dynamically turning on / off spatial domain elements (i.e., antennas, power amplifiers (PAs) or TxRUs (transceiver units or transmission radio units)) of a base station to save base station energy in a 5G system is described.

[0145] FIG. 13 is a diagram illustrating a method for adapting an antenna of a base station for energy saving in a wireless communication system according to one embodiment of the present disclosure.

[0146] Referring to FIG. 13, the base station can adjust the Tx antenna port per RU (radio unit) for network energy savings (NWES) (1301). For example, since the PA of the base station accounts for most of the energy consumption of the base station, the base station can turn off the Tx antenna to save energy. At this time, the base station can refer to and use the RSRP (reference signal received power), CQI (channel quality indicator), and RSRQ (reference signal received quality) of the UE to determine whether the Tx antenna can be turned off. The base station can perform signal transmission by adjusting the number of activated Tx antennas for each UE group or UE. At this time, the base station can set information including one or more of beam information according to antenna on / off or reference signal information (e.g., one or more of CSI resource, CSI resource set, or CSI report) to the UE through higher layer signaling (e.g., RRC signaling) or DCI signaling. Additionally, the base station can configure different antenna information for each BWP and reset the antenna information according to the BWP change. Furthermore, the base station can receive CSI feedback from the terminal to determine whether SD adaptation is possible. The base station can decide SD adaptation (based on the CSI feedback). The base station can receive multiple feedbacks from the terminal through antenna structure hypotheses of various antenna patterns for SD adaptation.

[0147] More specifically, the base station may apply multiple types (e.g., two types) of SD adaptation for energy saving (1302). For example, the multiple types may include Type 1 SD adaptation (1303) and Type 2 SD adaptation (1304).

[0148] When Type 1 SD adaptation (1303) is applied, the base station can adapt the number of antenna ports while maintaining the number of physical antenna elements per antenna port (i.e., logical port). At this time, the RF characteristics (e.g., tx power, beam) per port can be the same. Therefore, the terminal can perform measurements by combining the CSI-RS of the same port during CSI measurements (e.g., L1-RSRP (layer 1-RSRP), L3-RSRP (layer 3-RSRP), etc.).

[0149] Alternatively, when Type 2 SD adaptation (1304) is applied, the base station can have the same number of antenna ports (i.e., logical ports) and turn on / off physical antenna elements per port (1304). At this time, RF characteristics per port may vary. During CSI measurement, the terminal can distinguish the CSI-RS of the same port and perform measurements separately. The base station can save energy through one or more of multiple types of SD adaptation methods, including the two types of SD adaptation methods described above.

[0150] Below, a PRACH adaptation operation and a method and device for setting the PRACH adaptation operation for energy saving of a base station in a 5G system are described.

[0151] FIG. 14a and FIG. 14b are diagrams illustrating an example of a PRACH adaptation operation of a base station according to one embodiment of the present disclosure.

[0152] According to Fig. 14a, the base station can set PRACH adaptation for energy saving. At this time, the PRACH period can be changed by considering the overall mobility and number of terminals as a method of PRACH adaptation (PRACH adaptation case 1, 1401). According to Fig. 14b, when the number of terminals considering a specific beam is small or nonexistent, the base station can apply PRACH adaptation by turning off a specific PRACH occasion (PRACH occasion can be used interchangeably with RO hereinafter) connected to the beam (e.g., SSB) (PRACH adaptation case 2, 1404).

[0153] FIG. 14A is a diagram illustrating an example of a PRACH adaptation operation of a base station according to an embodiment of the present disclosure. In the case of Case 1 (1401), a terminal may be configured with two PRACH occasions, PRACH occasion#0 (1402) and PRACH occasion#1 (1403), from the base station through higher layer signaling. In this case, for example, a specific PRACH occasion#0 (1402) may be configured as a resource always used for PRACH transmission without considering PRACH adaptation. On the other hand, for energy saving of the base station, a specific PRACH occasion#1 (1403) may be used as an occasion to which PRACH adaptation is applicable. The two PRACH occasions are configured through different higher layer signaling and may be operated simultaneously.

[0154] Afterwards, based on the configured PRACH occasion#1(1403), if the number of currently activated terminals or traffic requests is small, the base station can turn off (or deactivate) PRACH occasion#1(1403) and perform initial access and PRACH reception operations only through PRACH occasion#0(1402) with a long period of 20 ms. On the other hand, if the number of terminals camping on the base station increases, the base station can turn on (or activate) PRACH occasion#1(1403) and perform initial access and PRACH reception operations based on a shorter period (for example, 10 ms). At this time, the base station can signal that PRACH adaptation is applied using upper layer signaling and L1 signaling, and in the case of PRACH occasion#1(1403), the period of PRACH occasion#1(1403) can be changed and operated according to PRACH adaptation.

[0155] FIG. 14B is a diagram illustrating another example of a PRACH adaptation operation of a base station according to an embodiment of the present disclosure. Furthermore, according to case 2 (1404), a terminal may be configured with two PRACH occasions, PRACH occasion #0 (1405) and PRACH occasion #1 (1406), from the base station through higher layer signaling. In this case, for example, a specific PRACH occasion #0 (1405) may be configured as a resource always used for PRACH transmission without considering PRACH adaptation. On the other hand, for energy saving of the base station, a specific PRACH occasion #1 (1406) may be used as an occasion to which PRACH adaptation is applicable.

[0156] Thereafter, if the base station determines that the number of terminals in specific SSB#0 and SSB#1 is small or non-existent, the base station can set and instruct the terminal to turn off the PRACH occasion(1407) of the PRACH occasion#1(1405) associated with the corresponding SSB#0 and SSB#1 through upper layer signaling and L1 signaling. In the above operation, the base station can determine whether to apply PRACH adaptation based on, for example, the frequency of receiving the PRACH through the PRACH occasion during a specific period.

[0157] The above-described methods are not limited to what is described above, and can be extended to apply N PRACH occasion configurations and various periods and SSB patterns in ssb-positionInburst. For example, there are N PRACH occasion configurations between a base station and a terminal, and at least one PRACH occasion configuration among them can always be used for PRACH transmission regardless of the energy saving configuration or PRACH adaptation configuration of the base station. Other PRACH occasions are PRACH occasions to which PRACH adaptation can be applied, and the same or different periods and / or the same or different SSB patterns can be applied to each PRACH occasion. Through the above method, the base station can apply PRACH adaptation and obtain an energy saving effect, while ensuring contention performance during PRACH transmission for initial access of the terminal.

[0158] FIG. 15 is a diagram illustrating an example of a PRACH adaptation operation of a base station according to an embodiment of the present disclosure. Referring to FIG. 15, the base station can configure two different PRACH configurations to a terminal through higher layer signaling. More specifically, the base station can configure PRACH occasion#0 (1501) with a long period and PRACH occasion#1 (1502) with a short period for applying PRACH adaptation. At this time, a valid PRACH occasion for PRACH transmission can be determined through one of the following methods.

[0159] [Method 1]

[0160] Method 1 proposes a PRACH transmission method in which the PRACH occasion and PRACH configuration are selected based on the earliest (closest) PRACH occasion.

[0161] A UE can determine the first PRACH occasion set for PRACH transmission and perform a PRACH transmission operation based on the PRACH configuration that sets the corresponding PRACH occasion. More specifically, when UE#0 performs PRACH transmission, UE#0 can select the closest PRACH occasion RO#0 (1503) and perform a PRACH transmission operation through the PRACH occasions set as PRACH configuration#0 (1501) corresponding to the PRACH occasion RO#0 (1504). On the other hand, UE#1 can select the closest PRACH occasion RO#1 (1505) for PRACH transmission. Thereafter, UE#1 can perform a PRACH transmission operation based on PRACH configuration#1 (1502) corresponding to RO#1 (1505) (1506). Through this method, the UE can reduce the complexity of the UE by performing a PRACH transmission operation based on a single PRACH configuration setting. Additionally, delay performance can be guaranteed by selecting the fastest PRACH occasion and operating (i.e., PRACH transmission delay can be prevented).

[0162] [Method 2]

[0163] Method 2 proposes a PRACH transmission method in which all PRACH occasions are considered based on multiple PRACH configurations.

[0164] The terminal can determine a valid PRACH occasion for PRACH transmission and transmit the PRACH by considering multiple PRACH configurations #0 (1501) and #1 (1502) set by the base station through upper layer signaling for PRACH transmission (1507). In this case, the terminal can transmit the PRACH based on a greater number of PRACH occasions, thereby improving competition between PRACH transmissions.

[0165] As in the above methods, the base station can set multiple PRACH configurations for PRACH adaptation and receive PRACHs from the terminal based on these configurations. At this time, the base station can select and / or activate or / and deactivate some of the multiple PRACH configurations through upper layer signaling and L1 signaling, thereby instructing PRACH adaptation.

[0166] Below, we describe methods for setting up a PRACH configuration to support the above operations. The base station can set one or more PRACH configurations to the terminal through higher-layer signaling (e.g., system information block or RRC signaling). In this case, the base station can set up a PRACH occasion corresponding to the default operation using existing PRACH configuration setting information. PRACH adaptation may not be applied to the corresponding PRACH occasion.

[0167] In addition, the base station may configure multiple additional PRACH configurations for energy saving. More specifically, the base station may additionally configure PRACH configuration-related information as exemplified in Table 4 below. At this time, an additional PRACH configuration ID may be newly added for PRACH adaptation to distinguish between multiple PRACH configurations, and the configuration information in Table 4 below may correspond to the PRACH configuration ID. The information in Table 4 below is merely an example, and the contents of the present disclosure are not limited by the contents of Table 4.

[0168] RACH-ConfigCommon-r19 ::= SEQUENCE {rach-ConfigGeneric RACH-ConfigGeneric,totalNumberOfRA-Preambles INTEGER (1..63)ssb-perRACH-OccasionAndCB-PreamblesPerSSB CHOICE {oneEighth ENUMERATED {n4,n8,n12,n16,n20,n24,n28,n32,n36,n40,n44,n48,n52,n56,n60,n64},oneFourth ENUMERATED {n4,n8,n12,n16,n20,n24,n28,n32,n36,n40,n44,n48,n52,n56,n60,n64},oneHalf ENUMERATED {n4,n8,n12,n16,n20,n24,n28,n32,n36,n40,n44,n48,n52,n56,n60,n64},one ENUMERATED {n4,n8,n12,n16,n20,n24,n28,n32,n36,n40,n44,n48,n52,n56,n60,n64},two ENUMERATED {n4,n8,n12,n16,n20,n24,n28,n32},four INTEGER (1..16),eight INTEGER (1..8),sixteen INTEGER (1..4)}prach-RootSequenceIndex CHOICE {l839 INTEGER (0..837),l139 INTEGER (0..137)},msg1-SubcarrierSpacing SubcarrierSpacing쪋}RACH-ConfigDedicated-r19 ::= SEQUENCE {cfra CFRA OPTIONAL, -- Need Sra-Prioritization RA-Prioritization...,[[ra-PrioritizationTwoStep-r16 RA-Prioritizationcfra-TwoStep-r16 CFRA-TwoStep-r16]]}RACH-ConfigGeneric-r19 ::= SEQUENCE {prach-ConfigurationIndex INTEGER (0..255),msg1-FDM ENUMERATED {one, two, four, eight},msg1-FrequencyStart INTEGER (0..maxNrofPhysicalResourceBlocks-1),zeroCorrelationZoneConfig INTEGER(0..15),preambleReceivedTargetPower INTEGER (-202..-60),preambleTransMax ENUMERATED {n3, n4, n5, n6, n7, n8, n10, n20, n50, n100, n200},powerRampingStep ENUMERATED {dB0, dB2, dB4, dB6},ra-ResponseWindow ENUMERATED {sl1, sl2, sl4, sl8, sl10, sl20, sl40, sl80},...,[[prach-ConfigurationPeriodScaling-IAB-r16 ENUMERATED {scf1,scf2,scf4,scf8,scf16,scf32,scf64}prach-ConfigurationFrameOffset-IAB-r16 INTEGER (0..63)prach-ConfigurationSOffset-IAB-r16 INTEGER (0..39)ra-ResponseWindow-v1610 ENUMERATED { sl60, sl160}prach-ConfigurationIndex-v1610 INTEGER (256..262)]],[[ra-ResponseWindow-v1700 ENUMERATED {sl240, sl320, sl640, sl960, sl1280, sl1920, sl2560}]]}.

[0169] Thereafter, the base station can configure (or instruct) selection or activation or / and deactivation of one or more of the PRACH configurations through at least one of SIB update, RRC reset, MAC CE, cell-specific or group common DCI, and UE-specific DCI. At this time, scheduling of the configuration information can be indicated by DCI transmitted through CORESET#0, and in the case of DCI used for PRACH adaptation, it can be transmitted based on a new RNTI for NES.

[0170] Considering the above configuration information, some of the information included in the existing RRC message may be newly included in the Rel-19 configuration for PRACH adaptation. At this time, when multiple PRACH configurations are selected, activated, or configured for PRACH adaptation and PRACH transmission, the total number of PRACH preambles considered for PRACH transmission, the total number of PRACH occasions that can be FDMed, and the total number of PRACH resources may be limited so as not to exceed values ​​that can be configured through the existing PRACH configuration. For example, the number of PRACH preambles may be limited to min(63, sum(configured PRACH preambles)), which cannot exceed 63, and the maximum number of PRACH occasions that can be FDMed simultaneously may be limited to 8, such as min(8, sum(configured msg1-FDMs)). The above-described content is an embodiment of the present disclosure and may be applied to all values ​​that can be configured through the existing PRACH configuration. Additionally, for a terminal with Rel-19 NES capability, the maximum value of at least one of the total number of PRACH preambles considered, the total number of PRACH occasions that can be FDMed, and the total number of PRACH resources may be changed. Additionally, an additional PRACH configuration to support two-step RA operation may be applied for PRACH adaptation.

[0171] FIG. 16 is a diagram illustrating another example of a PRACH ramping-up operation of a base station and a terminal according to one embodiment of the present disclosure.

[0172] Referring to FIG. 16, a base station can set two different PRACH configurations to a terminal through upper layer signaling. More specifically, a PRACH occasion#0 (1601) with a long period and a PRACH occasion#1 (1602) with a short period for applying PRACH adaptation can be set. At this time, depending on the two PRACH configuration settings, the PRACH occasions may overlap at least partly in the time domain, the frequency domain, or the time and frequency domains, or may be time division multiplexed (TDM) or / and frequency division multiplexed (FDM).

[0173] The base station can set configuration information for PRACH ramping-up to the terminal (e.g., at least one of preambleReceivedTargetPower, preambleTransMax, powerRampingStep, and ra-ResponseWindow). At this time, if the base station sets a common PRACH ramping-up transmission considering the two PRACH configurations set above, the terminal can monitor a response (e.g., RAR) to the PRACH transmission during the set time window after the PRACH transmission from the base station. If the terminal does not receive a response to the PRACH during the time window, the terminal can ramp up and retransmit the PRACH. More specifically, the terminal (UE#0) can perform an initial PRACH transmission at the nearest PRACH occasion (RO#0 according to PRACH configuration #0 (1601)) where PRACH transmission is possible. At this time, the PRACH transmission power can be determined as preambleReceivedTargetPower: -104, preambleTrans: 1 based on the common configuration#0 (1603) set by the base station. Afterwards, the terminal can monitor the RAR for s12 (12 slots, ra-ResponseWindow setting according to common configuration#0 (1603)) in the time window (1605) by considering the PDCCH that can receive the RAR as a response to the PRACH after the PRACH transmission. Afterwards, if the RAR is not received during the time window (1605), the terminal can transmit the PRACH at the nearest PRACH occasion (RO#4 according to PRACH configuration #1 (1602) for NES) after the time window ends.At this time, the transmission power of the corresponding PRACH is ramped up by the set powerRampingStep of 4 dB, and is determined as preambleReceivedTargetPower: -100, preambleTrans: 2, so that the PRACH can be transmitted. Similarly, the terminal monitors the RAR during the time window (1606), and if the RAR is not received during the time window (1606), the terminal can perform PRACH transmission considering the ramping-up operation at the next nearest PRACH occasion (RO#2 according to PRACH configuration #0 (1601)). At this time, the maximum number of PRACHs transmitted after ramping-up can be set by the base station.

[0174] Through the above method, the terminal can perform a PRACH ramping-up operation through multiple PRACH occasions set for PRACH adaptation. Through the above method, the terminal can perform ramping-up and PRACH transmission with minimal delay, and the fairness of competition in PRACH transmission can be improved through the common ramping-up operation.

[0175] FIG. 17 is a diagram illustrating another example of a PRACH ramping-up operation between a base station and a terminal according to an embodiment of the present disclosure. Referring to FIG. 17, the base station can set two different PRACH configurations to the terminal through upper layer signaling. More specifically, a PRACH occasion#0 (1701) having a long period and a PRACH occasion#1 (1702) having a short period for applying PRACH adaptation can be set. At this time, depending on the two PRACH configuration settings, the PRACH occasions may overlap at least partly in the time domain, the frequency domain, or the time and frequency domains, or may be TDM or / and FDM.

[0176] The base station can configure the configuration information for PRACH ramping-up (e.g., at least one of preambleReceivedTargetPower, preambleTransMax, powerRampingStep, and ra-ResponseWindow) differently for each PRACH occasion. At this time, the base station can determine the configuration information for PRACH ramping-up transmission differently by considering each of the two PRACH configurations configured above. For example, in the case of NES PRACH configuration#1 (1702), where PRACH occasions are configured with a shorter cycle, the power ramping-up step can be configured to have a smaller number of retransmissions. On the other hand, PRACH configuration#0 (1701), which generally has a long cycle, can be configured to have a larger power ramping-up step and a smaller number of retransmissions.

[0177] Through the above configuration information, the terminal can perform PRACH transmission, and the terminal can monitor a response (e.g., RAR) to the PRACH transmission from the base station during a configured time window after the PRACH transmission. If the terminal does not receive a response to the PRACH during the time window, the terminal can ramp up and retransmit the PRACH. More specifically, the terminal (UE#0) can perform the first PRACH transmission at the nearest PRACH occasion (RO#0 according to PRACH configuration #0 (1701)) where PRACH transmission is possible. At this time, the PRACH transmission power can be determined from the base station as preambleReceivedTargetPower: -104, preambleTrans: 1 based on the corresponding PRACH configuration#0 (1701) (1703). Afterwards, the terminal can monitor RAR for s12 (12 slots, ra-ResponseWindow setting of PRACH configuration #0 (1701)) as a time window (1704) considering PDCCH that can receive RAR as a response to PRACH after PRACH transmission. If RAR is not received during the time window (1704), the terminal can transmit PRACH at the nearest PRACH occasion (RO#4 according to PRACH configuration #1 (1702) for NES) after the time window ends. At this time, the transmission power of the corresponding PRACH can be determined by one of the following methods or a combination thereof.

[0178] [Method 1]

[0179] The UE can perform PRACH retransmission considering the PRACH ramping-up operation based on the PRACH configuration setting information corresponding to the PRACH occasion used for the initial PRACH transmission. The method 1 can support the PRACH ramping-up operation that improves the complexity of the UE. More specifically, the UE can perform the PRACH transmission by determining the preambleReceivedTargetPower as -98 (1705) considering the preambleRampingStep: 6dB (indicated by PRACH configuration #0) from the existing transmission power of -104 in the PRACH transmission considering the ramping-up after the initial PRACH transmission according to PRACH configuration #0 (1701). If the UE performs the third PRACH transmission thereafter, the UE can perform the PRACH transmission by determining the preambleReceivedTargetPower as -92 (1708) considering the preambleRampingStep: 6dB.

[0180] [Method 2]

[0181] The UE can determine the transmission power of the PRACH by referring to the PRACH configuration of the PRACH occasion in which the PRACH transmission is performed. More specifically, when the PRACH transmission is performed through another PRACH configuration#1(1702) after the initial PRACH transmission according to PRACH configuration#0(1701), the UE can perform PRACH transmission based on the configuration information of the PRACH configuration#1(1702) and the number of PRACHs transmitted through the PRACH occasion connected to the PRACH configuration#1(1702). Accordingly, when the UE transmits the PRACH in the PRACH occasion (RO#4) according to PRACH configuration#1(1702), the UE can consider the PRACH transmission in the occasion as the first transmission of the PRACH (according to PRACH configuration#1(1702)) and transmit it with preambleReceivedTargetPower: -99 (1706). If the terminal performs PRACH transmission again in RO#2 according to PRACH configuration #0 (1701) (even if preambleTrans: 3), the terminal can perform PRACH transmission with preambleReceivedTargetPower of -104+6 = -98 (1909) because it is the second PRACH transmission related to PRACH configuration #0 (1701).

[0182] According to Method 2, the maximum number of retransmissions and / or transmission power can be determined according to the PRACH configuration corresponding to each PRACH occasion, thereby enabling the UE to manage and transmit PRACH transmission power according to each PRACH occasion. However, in this case, the UE may require the capability to store and manage individual PRACH power control information. This operation can be configured and performed if the UE reports the capability to the base station.

[0183] [Method 3]

[0184] After the initial PRACH transmission, the UE can perform the PRACH ramping-up operation by applying only different ramping-up step sizes for the PRACH ramping-up operation. More specifically, preambleReceivedTargetPower: -104 (transmission power according to PRACH configuration #0 (1701)) is applied to the initial PRACH transmission according to PRACH configuration #0 (1701). In the subsequent PRACH transmission, considering that it is a transmission in a PRACH occasion according to PRACH configuration #1 (1702), preambleReceivedTargetPower: -99 (transmission power according to PRACH configuration #1 (1702)) and powerRampingStep: 2dB of PRACH configuration #1 (1702) of the corresponding PRACH occasion (RO#4) can be applied to transmit the PRACH with preambleReceivedTargetPower: -97 (=-99 + 2) (1707). Afterwards, when the terminal performs the third PRACH retransmission in the PRACH occasion (RO#2) according to PRACH configuration #0 (1701), the terminal can perform the PRACH transmission based on preambleReceivedTargetPower: -92 (-104+(6*2)) (1710) considering the ramping-up size (6dB) of the setting of the PRACH configuration #0 (1701) from the previous -97. In other words, the third PRACH retransmission is performed based on the transmission power that considers the ramping-up size of 6dB of PRACH configuration #0 (1701) twice in the preambleReceivedTargetPower of -104 of PRACH configuration #0 (1701).The above method has the advantage of being able to provide PRACH transmission while improving terminal complexity and interference for each occasion.

[0185] Through the above methods, the terminal can apply a PRACH ramping-up operation through multiple PRACH occasions configured for PRACH adaptation. Through the above methods, the terminal can perform ramping-up and PRACH transmission with minimal delay, and the fairness of PRACH transmission competition can be improved through the common ramping-up operation.

[0186] FIG. 18 is a diagram illustrating another example of a PRACH ramping-up operation between a base station and a terminal according to an embodiment of the present disclosure. Referring to FIG. 18, the base station can set two different PRACH configurations to the terminal through upper layer signaling. More specifically, the base station can set PRACH occasion#0 (1801) having a long period and PRACH occasion#1 (1802) having a short period for applying PRACH adaptation. At this time, depending on the two PRACH configuration settings, the PRACH occasions may overlap at least partly in the time domain, the frequency domain, or both in the time and frequency domains, or may be TDM and / or FDM.

[0187] The base station can set configuration information for PRACH ramping-up (e.g., at least one of preambleReceivedTargetPower, preambleTransMax, powerRampingStep, and ra-ResponseWindow) to the terminal. At this time, the base station can set PRACH ramping-up transmission considering each PRACH configuration set above. At this time, the terminal can monitor a response (e.g., RAR) to the PRACH transmission during the set time window after the PRACH transmission from the base station. If the terminal does not receive a response to the PRACH during the time window, the terminal can ramp up and retransmit the PRACH.

[0188] More specifically, the terminal (UE#0) can perform the first PRACH transmission at the nearest PRACH occasion #0 (1801) where PRACH transmission is possible. At this time, the PRACH transmission power is determined as preambleReceivedTargetPower: -104, preambleTrans: 1 based on the common configuration#0 (1803) set by the base station, so that the PRACH can be transmitted. Thereafter, the terminal can perform a PRACH transmission operation considering PRACH ramping-up based on the corresponding PRACH configuration information only at the selected PRACH occasion. For example, if the terminal decides to perform the first PRACH transmission through the PRACH occasion corresponding to PRACH configuration#0 (1801), the terminal can perform PRACH retransmission considering PRACH ramping at the PRACH occasion corresponding to the PRACH configuration#0 (1801) (1803). At this time, the transmission power in PRACH retransmission can be determined as -102, which is the initial transmission power of -104+2.

[0189] Similarly, if the terminal decides to perform the first PRACH transmission through a PRACH occasion corresponding to PRACH configuration#1 (1802), the terminal can perform PRACH retransmission considering PRACH ramping-up in the corresponding PRACH occasion (1805). At this time, the initial PRACH transmission power is preambleReceivedTargetPower: -100, and the terminal can transmit the PRACH with the transmission power increased by 4 dB for each retransmission.

[0190] At this time, the method of selecting a PRACH occasion at which the terminal performs the first PRACH transmission can be set by the base station or determined according to a priority rule.

[0191] Through the above method, the terminal can apply a PRACH ramping-up operation through multiple PRACH occasions set for PRACH adaptation. Through the above method, PRACH transmission can be performed while ramping up with minimal latency, and the fairness of PRACH transmission competition can be improved through a common ramping-up operation.

[0192] Hereinafter, PRACH configuration methods for supporting the above operations are described. The base station can set configuration information for PRACH ramping-up to the terminal through upper layer signaling (e.g., SIB or RRC signaling). More specifically, the base station can additionally set information related to the PRACH ramping-up configuration as exemplified in Table 5 below. At this time, the degree of Table 5 may be set separately for each of multiple PRACH configurations, or the configuration information in Table 5 may be set so that the information below is commonly used. In addition, one or more of the configuration information for PRACH ramping-up described in Table 5 may be set for Rel-19. In addition, the common PRACH ramping-up configuration may be included and set in RACH-ConfigGeneric.

[0193] RACH-Config-r19 ::= SEQUENCE {preambleReceivedTargetPower INTEGER (-202..-60),preambleTransMax ENUMERATED {n3, n4, n5, n6, n7, n8, n10, n20, n50, n100, n200},powerRampingStep ENUMERATED {dB0, dB2, dB4, dB6},ra-ResponseWindow ENUMERATED {sl1, sl2, sl4, sl8, sl10, sl20, sl40, sl80},...,}

[0194] The PRACH preambleReceivedTargetPower value determined through the above setting information and examples is P for actual PRACH transmission. 0_PRE can be applied to determine.

[0195] Figure 19 is a flowchart illustrating the operation of a terminal applying an energy-saving method for a wireless communication system according to one embodiment of the present disclosure. Various modifications may be made to the method illustrated in the flowchart of Figure 19. For example, although illustrated as a series of steps, the various steps in each drawing may overlap, occur in parallel, occur in different orders, or occur multiple times. In other examples, steps may be omitted or replaced with other steps.

[0196] Based on FIG. 19, the operation of a terminal for PRACH ramping-up during a PRACH adaptation operation for energy saving by a base station is described. Referring to FIG. 19, in step 1901, the terminal can receive two different PRACH configuration settings from the base station through higher layer signaling (e.g., RRC or SIB). The PRACH configuration settings can follow the content described above, and it is also possible for two or more pieces of PRACH configuration settings to be transmitted. In step 1902, the terminal can receive PRACH ramping-up related settings information from the base station through higher layer signaling (e.g., RRC or SIB). Step 1902 can also be performed together with step 1901.

[0197] In step 1903, the terminal can determine the PRACH transmission power based on the configured information and transmit the first PRACH. In step 1904, the terminal can monitor a response (e.g., RAR) to the PRACH transmission during a time window based on the configured information. The terminal can determine whether or not an RAR has been received during the time window. In step 1905, if a response to the PRACH transmission is not received during the time window, the terminal can transmit a PRACH with ramping-up applied. Here, at least one of the PRACH transmission power, the degree of ramping-up, or the PRACH occasion during which the PRACH is transmitted can be determined according to the above-described contents.

[0198] For specific details of terminal operation according to one embodiment of the present disclosure described above, reference may be made to the description of one embodiment of the present disclosure described above.

[0199] FIG. 20 is a flowchart illustrating the operation of a base station applying an energy-saving method for a wireless communication system according to one embodiment of the present disclosure. Various modifications may be made to the method illustrated in the flowchart of FIG. 20 . For example, although illustrated as a series of steps, the various steps in each drawing may overlap, occur in parallel, occur in different orders, or occur multiple times. In other examples, steps may be omitted or replaced with other steps.

[0200] Referring to FIG. 20, in step 2001, the base station can transmit two different pieces of PRACH configuration setting information to the terminal through higher layer signaling (e.g., RRC or SIB). The PRACH configuration setting information can follow the content described above, and it is also possible for two or more pieces of PRACH configuration setting information to be transmitted. In step 2002, the base station can transmit PRACH ramping up related setting information through higher layer signaling (e.g., RRC or SIB). Step 2002 can also be performed together with step 2001. In step 2003, the base station can receive a PRACH based on the configured information. At least one of the transmission power of the PRACH, the degree of ramping-up, or the PRACH occasion in which the PRACH is transmitted can be determined according to the content described above.

[0201] For specific details of the base station operation according to one embodiment of the present disclosure described above, reference may be made to the description of one embodiment of the present disclosure described above.

[0202] The above flowchart illustrates exemplary methods that can be implemented according to the principles of the present disclosure, and various modifications may be made to the methods depicted in the flowcharts herein. For example, although depicted as a series of steps, various steps in each drawing may overlap, occur in parallel, occur in different orders, or occur multiple times. In other instances, steps may be omitted or replaced with other steps.

[0203] According to various embodiments of the present disclosure, a base station in a communication system may perform PRACH adaptation transmission to reduce energy consumption. At this time, the base station may configure and operate PRACH adaptation at two different PRACH occasions. More specifically, a PRACH occasion for initial access of a legacy terminal that does not apply PRACH adaptation and an additional PRACH occasion for a Rel-19 terminal that can apply PRACH adaptation may be configured, and PRACH adaptation may be applied to the additional PRACH occasion. At this time, the base station may transmit configuration information to support ramping-up transmission of PRACH transmission to manage interference of the PRACH transmission of the terminal. At this time, in the case of energy saving for PRACH adaptation, since the number of PRACH resources is reduced, the terminals may transmit contention-based PRACH using fewer PRACH resources, which may make interference during PRACH transmission vulnerable. To manage this, a ramping-up operation may be performed together with the PRACH adaptation operation.

[0204] According to various embodiments of the present disclosure, a terminal may receive a PRACH occasion configured through an existing PRACH configuration from a base station and a PRACH occasion for PRACH adaptation. Thereafter, the terminal may activate or deactivate the PRACH occasion configured for PRACH adaptation according to the base station's configuration. At this time, the cycle of the PRACH occasion or the number of TDM / FDM resources may be changed due to PRACH adaptation. Thereafter, a PRACH ramping-up operation may be performed through the PRACH occasion resources.

[0205] According to various embodiments of the present disclosure, a PRACH occasion through an existing PRACH configuration and a PRACH occasion for PRACH adaptation can be configured.

[0206] According to various embodiments of the present disclosure, PRACH occasion through existing PRACH configuration and PRACH ramping-up configuration information according to PRACH occasion for PRACH adaptation can be configured.

[0207] According to various embodiments of the present disclosure, a terminal may perform a PRACH ramping-up operation by considering each PRACH occasion or a plurality of different PRACH occasions according to a setting from a base station.

[0208] According to various embodiments of the present disclosure, a method and device for operating a terminal / base station according to each of the above settings can be provided.

[0209] Various embodiments of the present disclosure may provide a configuration method via higher layer signaling (e.g., RRC signaling or SIB) for applying PRACH adaptation. According to various embodiments of the present disclosure, based on the configuration information, a terminal may determine a PRACH occasion for PRACH transmission and an SSB that is quasi-co-located (QCLed) with the corresponding PRACH occasion.

[0210] Various embodiments of the present disclosure allow a terminal to perform PRACH transmission after ramping up transmission power when no response to a PRACH is received during a time window after a PRACH transmission in a PRACH occasion considering multiple PRACH configurations.

[0211] FIG. 21 is a block diagram of a terminal according to one embodiment of the present disclosure.

[0212] Referring to FIG. 21, a terminal (2100) may include a transceiver (2101), a control unit (e.g., a processor) (2102), and a storage unit (e.g., a memory) (2103). The transceiver (2101), the control unit (2102), and the storage unit (2103) of the terminal (2100) may operate according to at least one or a combination of methods corresponding to the above-described embodiments. However, the components of the terminal (2100) are not limited to the illustrated example. According to other embodiments, the terminal (2100) may include more or fewer components than the components described above. In addition, in certain cases, the transceiver (2101), the control unit (2102), and the storage unit (2103) may be implemented in the form of a single chip.

[0213] The transceiver (2101) may, according to one embodiment, be composed of a transmitter and a receiver. The transceiver (2101) may transmit and receive signals with a base station. The signals may include control information and data. The transceiver (2101) 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 and frequency-downconverts the received signal. The transceiver (2101) may receive a signal through a wireless channel and output the signal to the control unit (2102), and may transmit a signal output from the control unit (2102) through the wireless channel.

[0214] The control unit (2102) may control a series of procedures that the terminal (2100) may perform according to the embodiments of the present disclosure described above. For example, the control unit (2102) may perform or control operations of the terminal to perform at least one or a combination of methods according to the embodiments of the present disclosure. The control unit (2102) may include at least one processor. For example, the control unit (2102) may include a communication processor (CP) that performs control for communication and an application processor (AP) that controls an upper layer (e.g., an application).

[0215] Figure 22 is a block diagram of a base station according to one embodiment.

[0216] Referring to FIG. 22, a base station (2200) may include a transceiver (2201), a control unit (e.g., a processor) (2202), and a storage unit (e.g., a memory) (2203). The transceiver (2201), the control unit (2202), and the storage unit (2203) of the base station (2200) may operate according to at least one or a combination of the methods corresponding to the above-described embodiments. However, the components of the base station (2200) are not limited to the illustrated example. According to other embodiments, the base station (2200) may include more or fewer components than the components described above. In addition, in certain cases, the transceiver (2201), the control unit (2202), and the storage unit (2203) may be implemented in the form of a single chip.

[0217] The transceiver (2201) may, according to one embodiment, be composed of a transmitter and a receiver. The transceiver (2201) may transmit and receive signals with a terminal. The signals may include control information and data. The transceiver (2201) 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 and frequency-downconverts the received signal. The transceiver (2201) may receive a signal through a wireless channel and output the signal to the control unit (2202), and may transmit the signal output from the control unit (2202) through the wireless channel.

[0218] The control unit (2202) may control a series of procedures so that the base station (2200) can operate according to the embodiments of the present disclosure described above. For example, the control unit (2202) may perform or control the operation of the base station to perform at least one or a combination of methods according to the embodiments of the present disclosure. The control unit (2202) may include at least one processor. For example, the control unit (2202) may include a communication processor (CP) that performs control for communication and an application processor (AP) that controls an upper layer (e.g., an application).

[0219] While the drawings illustrate different examples of user devices / base stations, various modifications to the drawings may be made. For example, the user devices / base stations may include any number of each component in any suitable arrangement. In general, the drawings do not limit the scope of the present disclosure to any particular configuration. Furthermore, while the drawings illustrate operating environments in which the various user devices / base stations described in this patent document may be utilized, such features may be utilized in any other suitable system.

[0220] While this disclosure has been described with exemplary embodiments, various modifications and variations will occur to those skilled in the art. It is intended that this disclosure encompass such modifications and variations as fall within the scope of the appended claims. The description in this application should not be construed as implying that any specific element, step, or function is essential to the scope of the claims. The scope of the patented subject matter is defined by the claims.

Claims

1. In a method performed by a terminal of a communication system, A step of receiving information about a default PRACH (physical random access channel) setting from a base station and information about a PRACH setting for PRACH adaptation; A step of performing an initial PRACH transmission based on the above default PRACH setting or PRACH setting for PRACH adaptation; A step of confirming that a response corresponding to the above first PRACH transmission is not received within the time window; A step of determining transmission power for PRACH retransmission; and A method characterized by comprising a step of performing the PRACH retransmission at a PRACH occasion closer in the time domain among the PRACH occasion related to the default PRACH setting or the PRACH occasion related to the PRACH setting for PRACH adaptation at a time point when the PRACH retransmission should be performed based on the transmission power.

2. In paragraph 1, A method characterized in that the above transmission power is determined based on transmission power information included in a PRACH setting related to the first PRACH transmission.

3. In paragraph 1, At least one PRACH configuration for PRACH adaptation is established via higher layer signaling, A method characterized in that each PRACH configuration for PRACH adaptation is associated with a PRACH configuration ID (identifier).

4. In paragraph 3, Further comprising a step of receiving information indicating activation or deactivation of a PRACH setting for at least one PRACH adaptation from the base station, A method characterized in that the information indicating the above activation or deactivation is received via MAC CE (medium access control-control element) or DCI (downlink control information).

5. In the method performed by the base station of the communication system, A step of transmitting information about a default PRACH (physical random access channel) setting to a terminal and information about a PRACH setting for PRACH adaptation; A step for confirming that the first PRACH has not been received from the terminal, wherein the first PRACH is based on the default PRACH setting or the PRACH setting for PRACH adaptation; and A step of receiving a PRACH retransmitted from the terminal, A method characterized in that the PRACH occasion at which the retransmitted PRACH is received corresponds to a PRACH occasion closer in the time domain among the PRACH occasion related to the default PRACH setting or the PRACH occasion related to the PRACH setting for PRACH adaptation at the time when PRACH retransmission must be performed.

6. In paragraph 5, A method characterized in that the transmission power of the retransmitted PRACH is based on transmission power information included in the PRACH setting related to the initial PRACH.

7. In paragraph 5, Information about PRACH configuration for at least one PRACH adaptation is transmitted via upper layer signaling, A method characterized in that each PRACH configuration for PRACH adaptation is associated with a PRACH configuration ID (identifier).

8. In paragraph 7, Further comprising a step of transmitting information indicating activation or deactivation of a PRACH setting for at least one PRACH adaptation to the terminal, A method characterized in that the information indicating the above activation or deactivation is received via MAC CE (medium access control-control element) or DCI (downlink control information).

9. At the terminal of the communication system, At least one transceiver; At least one processor communicatively connected to said at least one transceiver; and Communicably connected to at least one processor, and executable individually or in any combination of said at least one processor, such that said terminal: Receive information about default PRACH (physical random access channel) settings from a base station and information about PRACH settings for PRACH adaptation, Perform the first PRACH transmission based on the above default PRACH settings or PRACH settings for PRACH adaptation, Verify that no response corresponding to the above initial PRACH transmission has been received within the time window, A memory storing a command to determine a transmit power for PRACH retransmission; A terminal characterized in that it comprises a step of performing the PRACH retransmission at a PRACH occasion closer in the time domain among the PRACH occasion related to the default PRACH setting or the PRACH occasion related to the PRACH setting for PRACH adaptation at a time when the PRACH retransmission should be performed based on the transmission power.

10. In paragraph 9, A terminal characterized in that the above transmission power is determined based on transmission power information included in the PRACH setting related to the first PRACH transmission.

11. In paragraph 9, At least one PRACH configuration for PRACH adaptation is established via higher layer signaling, A terminal characterized in that each PRACH configuration for PRACH adaptation is associated with a PRACH configuration ID (identifier).

12. In paragraph 11, the command further causes the terminal to receive information indicating activation or deactivation of the PRACH configuration for the at least one PRACH adaptation from the base station, A terminal characterized in that the information indicating the above activation or deactivation is received through a MAC CE (medium access control-control element) or DCI (downlink control information).

13. In the base station of the communication system, At least one transceiver; At least one processor communicatively connected to said at least one transceiver; and Communicably connected to at least one processor, and executable individually or in any combination of said at least one processor, such that said base station: Transmit information about default PRACH (physical random access channel) settings to the terminal and information about PRACH settings for PRACH adaptation, A step for confirming that the first PRACH has not been received from the terminal, wherein the first PRACH is based on the default PRACH setting or the PRACH setting for PRACH adaptation, and A memory storing a command to receive a PRACH retransmitted from the terminal; A base station characterized in that the PRACH occasion at which the retransmitted PRACH is received corresponds to a PRACH occasion closer in the time domain among the PRACH occasion related to the default PRACH setting or the PRACH occasion related to the PRACH setting for PRACH adaptation at the time when PRACH retransmission must be performed.

14. In paragraph 13, A base station, characterized in that the transmission power of the retransmitted PRACH is based on transmission power information included in the PRACH setting related to the initial PRACH.

15. In paragraph 13, Information about PRACH configuration for at least one PRACH adaptation is transmitted via upper layer signaling, A base station characterized in that each PRACH configuration for PRACH adaptation is associated with a PRACH configuration ID (identifier).

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