Method and apparatus for controlling synchronization signals in a wireless communication system applying base station energy saving

Abstract

The disclosure relates to a 5G or 6G communication system for supporting a higher data transmission rate. In the disclosure, a method and apparatus for providing an energy saving mode of a base station are disclosed. In addition to an SCell having a simplified SSB transmission (SSB-less SCell), the base station can designate a reference cell serving as a QCL reference standard for a PDCCH DMRS for a UE and notify the designated reference cell to the UE through signaling. The reference cell can be a PCell or a second SCell among cells constituting a carrier aggregation, excluding the SCell having no SSB. The base station can designate an RS that the UE needs to refer to in the reference cell and notify the designated RS to the UE, thereby enabling the UE to determine a QCL of the corresponding cell.

Description

Technical Field

[0001] This disclosure relates to communication methods in wireless communication systems, and more particularly to methods and apparatus for energy saving in wireless communication systems. Background Technology

[0002] 5G mobile communication technology defines a wide frequency band, enabling high transmission rates and new services. It can be implemented not only in "sub-6GHz" bands such as 3.5GHz, but also in "above 6GHz" bands, including 28GHz and 39GHz, known as millimeter waves. Furthermore, to achieve transmission rates 50 times faster than 5G and ultra-low latency one-tenth that of 5G, 6G mobile communication technology (referred to as "super 5G systems") in terahertz bands (e.g., the 95GHz to 3THz band) has been considered.

[0003] In the early stages of 5G mobile communication technology, to support services related to enhanced mobile broadband (eMBB), ultra-reliable and low-latency communication (URLLC), and massive machine-type communication (mMTC) and to meet the performance requirements associated with these technologies, standardization work has been underway in the following areas: beamforming and massive MIMO for mitigating radio wave path loss and increasing radio wave transmission distance in millimeter waves; digital parameter sets for efficient utilization of millimeter wave resources and dynamic operation of time slot formats (e.g., operating multiple subcarrier spacings); initial access technologies to support multi-beam transmission and the definition and operation of broadband, BWP (bandwidth portion); new channel coding methods such as LDPC (low-density parity-check) codes for high-capacity data transmission and polar codes for highly reliable transmission of control information; L2 preprocessing; and network slicing for providing dedicated networks tailored to specific services.

[0004] Currently, considering the services that 5G mobile communication technology will support, discussions are underway regarding improvements and performance enhancements to the initial 5G mobile communication technology. Physical layer standardization already exists for technologies such as: Vehicle-to-Everything (V2X) for assisting autonomous vehicles in making driving decisions based on information sent by the vehicle about its location and status and for enhancing user convenience; New Radio Unlicensed (NR-U) designed to ensure system operation in accordance with various regulatory requirements in unlicensed frequency bands; NR UE power saving; and Non-Terrestrial Network (NTN) (i.e., UE-satellite direct communication for ensuring coverage and positioning in areas where communication with terrestrial networks is unavailable).

[0005] Furthermore, standardization is underway in the wireless interface architecture / protocol domain for technologies such as: Industrial Internet of Things (IIoT) to support new services through interoperability and convergence with other industries; IAB (Integrated Access and Backhaul) for nodes to provide network service area extension by supporting wireless backhaul and access links in an integrated manner; mobility enhancements including conditional handover and DAPS (Dual Active Stack) handover; and two-step random access (2-step RACH for NR) to simplify the random access process. Standardization is also underway in the system architecture / service domain, involving 5G baseline architectures (e.g., service-based architectures or service-based interfaces) for combining Network Functions Virtualization (NFV) and Software-Defined Networking (SDN) technologies, and mobile edge computing (MEC) for UE location-based reception services.

[0006] If such a 5G mobile communication system is commercialized, the already exponentially increasing number of connected devices will be connected to the communication network, thus necessitating enhanced functionality and performance of the 5G mobile communication system, as well as integrated operation of connected devices. To this end, the following related new research is planned: effectively supporting extended reality (XR) such as augmented reality (AR), virtual reality (VR), and mixed reality (MR); improving 5G performance and reducing complexity by leveraging artificial intelligence (AI) and machine learning (ML); AI service support; metaverse service support; and drone communication.

[0007] Furthermore, this advancement in 5G mobile communication systems will lay the foundation for the development of technologies including: new waveforms to ensure terahertz band coverage for 6G mobile communication technologies; full-dimensional MIMO (FD-MIMO); multi-antenna transmission technologies (such as array antennas and large antennas); metamaterial-based lenses and antennas to improve terahertz band signal coverage; high-dimensional spatial multiplexing technologies using orbital angular momentum (OAM); reconfigurable smart surfaces (RIS); full-duplex technologies to improve the frequency efficiency of 6G mobile communication technologies and enhance system networks; AI-based communication technologies to optimize systems by leveraging satellites and AI (artificial intelligence) from the design phase and internalizing end-to-end AI support capabilities; and next-generation distributed computing technologies to enable services with complexity exceeding the operational limits of UEs by utilizing ultra-high-performance communication and computing resources. Summary of the Invention

[0008] Technical issues

[0009] The embodiments disclosed herein provide an apparatus and method for efficiently providing services in a mobile communication system. Specifically, a method and apparatus for efficiently performing base station energy-saving operations are disclosed.

[0010] The technical topics pursued in the embodiments described herein may not be limited to those described above, and those skilled in the art may consider other technical topics not mentioned herein from the various embodiments of this disclosure described below.

[0011] Technical solutions

[0012] To address the aforementioned problems, this disclosure provides a method performed by a terminal in a communication system, the method comprising receiving information about a reference cell from a base station, identifying a first secondary cell (SCell) as an SSB-free SCell, and identifying a second RS in a quasi-co-located (QCL) relationship with a first reference signal (RS) of the first SCell based on the information about the reference cell, wherein the second RS is the RS of the cell indicated by the information about the reference cell.

[0013] Alternatively, the second reference signal can be a synchronization signal block (SSB).

[0014] In addition, the method may also include sending terminal capability information supporting SSB-less SCells to the base station.

[0015] Furthermore, the maximum receive timing difference (MRTD) required for carrier aggregation (CA) of SCells without SSB can be greater than or equal to the MRTD required for in-band CA, and can be less than the MRTD required for inter-band CA.

[0016] Additionally, the method performed by the base station in the communication system may include the operation of identifying a first secondary cell (SCell) as an SCell without an SSB, and the operation of sending information about a reference cell to a terminal, wherein a first reference signal (RS) of the first SCell and a second RS are in a quasi-co-located (QCL) relationship, and the second RS is the RS of the cell indicated by the information about the reference cell.

[0017] Furthermore, the terminal in the communication system may include a transceiver and a controller, the controller being configured to: receive information about a reference cell from a base station; identify a first secondary cell (SCell) as an SSB-free SCell; and, based on the information about the reference cell, identify a second RS that is in a quasi-co-located (QCL) relationship with a first reference signal (RS) of the first SCell, wherein the second RS is the RS of the cell indicated by information associated with the reference cell.

[0018] Furthermore, the base station in the communication system may include a transceiver and a controller, the controller being configured to: identify that the first secondary cell (SCell) is an SCell without an SSB; and send information about a reference cell to the terminal, wherein a first reference signal (RS) of the first cell is in a quasi-co-located (QCL) relationship with a second RS, and the second RS is the RS of the cell indicated by the information about the reference cell.

[0019] Beneficial effects

[0020] The embodiments described herein provide an apparatus and method for preventing excessive energy consumption of base stations and achieving high energy efficiency of base stations in a mobile communication system.

[0021] Based on the following description, the beneficial effects that can be obtained from the embodiments set forth herein may not be limited to the effects described above, and those skilled in the art can clearly deduce and understand other effects not mentioned herein. Attached Figure Description

[0022] Figure 1 An example of the basic structure of the time-frequency domain in a 5G communication system is shown.

[0023] Figure 2 An example of time-domain mapping structure and beam scanning operation in a 5G system is shown.

[0024] Figure 3 An example of a random access procedure in a 5G system is shown.

[0025] Figure 4 This illustrates an example of the process by which a UE reports its capability information to a base station in a 5G system.

[0026] Figure 5 An example of base station beam allocation configured according to TCI status is shown.

[0027] Figure 6 An example of the PDCCH beam assignment method is shown.

[0028] Figure 7 The TCI indication MAC CE signaling structure for PDCCH DMRS is shown.

[0029] Figure 8 An example of CORESET and search space beam configuration is shown.

[0030] Figure 9 An example of configuring a 5G system by using three component carriers for each combination in the uplink and downlink is shown.

[0031] Figure 10An example of a QCL determination method for a UE is shown, according to a first embodiment, when the UE does not receive a MACCE activation command from the base station regarding the TCI state of the SCell.

[0032] Figure 11 An example of operation according to the second embodiment is shown.

[0033] Figure 12 An example of EPRE configuration for downlink signals in a 5G system is shown.

[0034] Figure 13 An example of a UE process according to an embodiment of this disclosure is shown.

[0035] Figure 14 An example of a base station process according to an embodiment of this disclosure is shown.

[0036] Figure 15 An example of a UE transceiver device in a wireless communication system according to an embodiment of the present disclosure is shown.

[0037] Figure 16 An example of the structure of a UE according to an embodiment of this disclosure is shown.

[0038] Figure 17 An example of the structure of a base station according to an embodiment of this disclosure is shown. Detailed Implementation

[0039] In the following, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. In describing the present disclosure, detailed descriptions of known functions or configurations incorporated herein will be omitted where it is determined that the description may unnecessarily obscure the subject matter of the disclosure. The terminology described below is defined in consideration of the functions in the present disclosure and may vary depending on the user, the user's intent, or habits. Therefore, the definitions of the terminology should be based on the content throughout the specification.

[0040] The advantages and features of this disclosure, as well as the ways in which they are implemented, will become apparent from the embodiments described in detail below with reference to the accompanying drawings. However, this disclosure is not limited to the embodiments set forth below, but can be implemented in a variety of different forms. The following embodiments are provided only to fully disclose this disclosure and to inform those skilled in the art of its scope, and this disclosure is limited only by the scope of the appended claims. Throughout the disclosure, the same or similar reference numerals denote the same or similar elements.

[0041] Here it will be understood that each box in a flowchart illustration, and combinations of boxes in a flowchart illustration, can be implemented by computer program instructions. These computer program instructions can be provided to the processor of a general-purpose computer, a special-purpose computer, or other programmable data processing apparatus to produce a machine such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create components for implementing the functions specified in one or more boxes of the flowchart. These computer program instructions can also be stored in a computer-usable or computer-readable storage medium that can instruct the computer or other programmable data processing apparatus to operate in a particular manner, such that the instructions stored in the computer-usable or computer-readable storage medium produce an article of manufacture including instruction components that implement the functions specified in the flowchart boxes or boxes. The computer program instructions can also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus, thereby producing a computer-implemented process, such that the instructions, which execute on the computer or other programmable apparatus, provide steps for implementing the functions specified in one or more boxes of the flowchart.

[0042] Furthermore, each box in the flowchart diagram can represent a module, code segment, or code section, which includes one or more executable instructions for implementing multiple specified logical functions. It should also be noted that in some alternative implementations, the functions mentioned in the boxes may appear out of order. For example, two boxes shown consecutively may actually be executed substantially simultaneously, or these boxes may sometimes be executed in reverse order, depending on the functions involved.

[0043] As used in embodiments of this disclosure, the term "cell" refers to a software element or hardware element, such as a field-programmable gate array (FPGA) or application-specific integrated circuit (ASIC), and a "cell" can perform certain functions. However, "cell" does not always have a meaning limited to software or hardware. A "cell" can be configured to be stored in addressable storage media or to run one or more processors. Thus, a "cell" includes, for example, software elements, object-oriented software elements, class elements or task elements, processes, functions, attributes, procedures, subroutines, program code segments, drivers, firmware, microcode, circuits, data, databases, data structures, tables, arrays, and parameters. Elements and functions provided by a "cell" can be combined into a smaller number of elements or "cells," or divided into a larger number of elements or "cells." Furthermore, elements and "cells" can be implemented to replicate one or more CPUs within a device or secure multimedia card. Additionally, a "cell" in an embodiment may include one or more processors.

[0044] In the following description of this disclosure, detailed descriptions of known functions or configurations incorporated herein will be omitted where it is determined that such description might unnecessarily obscure the subject matter of this disclosure. Various embodiments of this disclosure will be described below with reference to the accompanying drawings.

[0045] In the following description, for ease of description, terms for identifying access nodes, terms relating to network entities, terms relating to messages, terms relating to interfaces between network entities, terms relating to various identification information, etc., are used illustratively. Therefore, this disclosure is not limited to the terminology used herein, and other terms relating to subjects with equivalent technical meaning may be used.

[0046] In the following description, the terms "physical channel" and "signal" may be used interchangeably with the terms "data" or "control signal." For example, the term "physical downlink shared channel (PDSCH)" refers to the physical channel through which data is transmitted, but PDSCH can also be used to refer to "data." That is, in this disclosure, the expression "transmitting physical channel" can be interpreted as having the same meaning as the expression "transmitting data or signals through a physical channel."

[0047] In the following description of this disclosure, higher-layer signaling (or advanced signaling) refers to a signaling method that transmits signals from a base station to a terminal via a downlink data channel of the physical layer, or from a terminal to a base station via an uplink data channel of the physical layer. Higher-layer signaling may also be referred to as Radio Resource Control (RRC) signaling or Media Access Control (MAC) control element (CE).

[0048] In the following description, for ease of description, the terms and names defined in the 3GPP New Radio (3GPP NR) standard (or fifth-generation mobile communication standard) are used. However, this disclosure is not limited to these terms and names, and embodiments of this disclosure can also be applied to other communication systems with similar technical backgrounds or channel types. Examples of such communication systems may include LTE or LTE-A mobile communication systems and mobile communication technologies developing beyond 5G. Therefore, based on the determination of those skilled in the art, embodiments of this disclosure can be applied to other communication systems with some modifications without significantly departing from the scope of this disclosure.

[0049] In the following description, a base station is an entity that allocates resources to terminals and can be at least one of a gNode B, gNB, eNodeB, eNB, Node B, base station (BS), radio access unit, base station controller, and node on a network. A terminal can include user equipment (UE), mobile station (MS), cellular phone, smartphone, computer, or multimedia system capable of performing communication functions. Of course, examples of base stations and terminals are not limited to those mentioned above.

[0050] In the following description of this disclosure, higher-level signaling may refer to signaling corresponding to at least one of the following signaling, or a combination of one or more of them.

[0051] - Master Message Block (MIB)

[0052] - System Information Block (SIB) or SIB X (X=1, 2, ...)

[0053] - Radio Resource Control (RRC)

[0054] - Media Access Control (MAC) Unit (CE)

[0055] In addition, L1 signaling can refer to signaling corresponding to at least one of the signaling methods that use physical layer channels or signaling or a combination thereof.

[0056] - Physical Downlink Control Channel (PDCCH)

[0057] Downlink Control Information (DCI)

[0058] - UE-specific DCI

[0059] - Group Public DCI

[0060] - Public DCI

[0061] - Scheduling DCI (e.g., DCI used to schedule downlink or uplink data)

[0062] - Non-scheduled DCI (e.g., DCI not used for scheduling downlink or uplink data)

[0063] - Physical Uplink Control Channel (PUCCH)

[0064] - Uplink Control Information (UCI)

[0065] As used herein, the term “slot” can generally refer to a specific unit of time corresponding to a transmission time interval (TTI), specifically a slot used in a 5G NR system, or a slot or subframe used in a 4G LTE system.

[0066] To handle the recent exponential growth in mobile data traffic, initial standards have been completed for New Radio (NR) access technology, or fifth-generation (5G) systems, which are the next-generation communication systems following Long Term Evolution (LTE) (or Evolved Universal Terrestrial Radio Access (E-UTRA)) and Advanced LTE (LTE-A) (or Evolution of E-UTRA). While traditional mobile communication systems focus on conventional voice / data communications, 5G systems are designed to meet a variety of services and needs, such as Enhanced Mobile Broadband (eMBB) services to improve traditional voice / data communications, Ultra Reliable and Low Latency Communication (URLLC) services, and Massive Machine-Type Communication (MTC) services to support a large number of machine-to-machine communications.

[0067] Traditional LTE and LTE-A systems limit the transmission bandwidth per single carrier to a maximum of 20MHz, but 5G systems aim to provide ultra-high-speed data services of up to several Gbps by using ultra-wideband frequencies far exceeding 20MHz. Therefore, 5G systems consider ultra-high frequency bands ranging from several GHz to a maximum of 100 GHz as candidate frequencies, where ultra-wideband frequencies are relatively easy to guarantee. Furthermore, broadband frequencies for 5G systems can be secured through frequency rearrangement or allocation within the range of hundreds of MHz to several GHz used in traditional mobile communication systems.

[0068] Radio waves in the ultra-high frequency (UHF) band have wavelengths in the millimeter range, hence they are also called millimeter waves (mmWave). However, the path loss of radio waves in the UHF band increases proportionally with the frequency band, thus reducing the coverage area of ​​mobile communication systems.

[0069] To overcome the reduced coverage in the UHF band, beamforming technology is employed. This technology increases the distance radio waves travel by concentrating the energy radiated by multiple antennas onto a specific target point. In other words, signals using beamforming have a smaller beamwidth, and the radiated energy is concentrated within this narrower beamwidth, thus increasing the distance the radio waves travel. Beamforming can be applied to each of the transmitting and receiving nodes. Besides increasing coverage, beamforming also reduces interference in areas outside the beamforming direction. Proper operation of beamforming requires a method for accurately measuring the transmit / receive beams and transmitting feedback. Beamforming can be applied to control or data channels that have a one-to-one correspondence between the UE and the base station. Furthermore, beamforming can be applied to both control and data channels used to transmit common signals from the base station to multiple UEs in the system, such as synchronization signals, physical broadcast channel (PBCH), and system information, to further increase coverage. When beamforming technology is applied to public signals, beam scanning technology is additionally applied, so that the signal is transmitted after the beam direction is changed, thereby ensuring that the public signal can reach UEs located in specific locations within the cell.

[0070] Another requirement for 5G systems is ultra-low latency service, with transmission latency between the sender and receiver expected to be approximately 1 millisecond or less. As an attempt to reduce transmission latency, a frame structure design based on shorter Transmission Time Intervals (TTIs) than LTE and LTE-A is needed. The TTI is the basic unit of time used for scheduling; traditional LTE and LTE-A have a 1-millisecond TTI, corresponding to the length of a subframe. For example, to meet the requirements for ultra-low latency service, the short TTIs upon which 5G systems are based could be 0.5 milliseconds, 0.25 milliseconds, 0.125 milliseconds, etc., shorter than traditional LTE and LTE-A.

[0071] Figure 1 An example of the basic structure of the time-frequency domain in a 5G system is shown. That is, Figure 1 The basic structure of the time-frequency resource domain is shown, which is a radio resource domain used to transmit data or control channels for 5G systems.

[0072] refer to Figure 1 , Figure 1 The horizontal axis represents the time domain, and the vertical axis represents the frequency domain. The smallest transmission unit in the time domain of a 5G system is an Orthogonal Frequency Division Multiplexing (OFDM) symbol, a group of... Symbol 102 can form a time slot 106, a group of One time slot can constitute a subframe 105. A subframe 105 can have a length of 1.0 millisecond, and a group of ten subframes can constitute a 10-millisecond frame 114. The smallest transmission unit in the frequency domain is a subcarrier, and the total number of times is N. BW 104 subcarriers can constitute the transmission bandwidth of the entire system.

[0073] In the time-frequency domain, the basic unit of resources is the resource element (RE) 112, which can be represented by OFDM symbol index and subcarrier index. A resource block (RB) or physical resource block (PRB) can be formed by consecutive elements in the frequency domain. The number of subcarriers is defined as 110. In 5G systems, = 12, and the data rate can be increased proportionally to the number of RBs scheduled for the UE.

[0074] In 5G systems, base stations can map data in units of RBs (Resource Blocks), and typically, an RB can be scheduled for a specific UE to form a time slot. In other words, the basic time unit for scheduling in a 5G system can be a time slot, and the basic frequency unit for scheduling can be an RB.

[0075] Number of OFDM symbols The length is determined by the length of the cyclic prefix (CP) added to each symbol to prevent inter-symbol interference. For example, if a normal CP is applied, then... = 14; if extended CP is applied, then = 12. Extended CP is used in systems with longer radio wave transmission distances than normal CP, thus maintaining inter-symbol orthogonality. In the case of normal CP, the ratio between the CP length and the symbol length remains constant, ensuring that the overhead caused by CP remains constant regardless of the subcarrier spacing (SCS). That is, if the subcarrier spacing decreases, the symbol length may increase, thus increasing the CP length. Conversely, if the subcarrier spacing increases, the symbol length may decrease, thus decreasing the CP length. The symbol length and CP length can be inversely proportional to the subcarrier spacing.

[0076] To meet the diverse services and requirements of 5G systems, various frame structures can be supported by adjusting the subcarrier spacing. For example,

[0077] - In terms of operating frequency band, the larger the subcarrier spacing, the more beneficial it is for the recovery of phase noise in the high-frequency band.

[0078] In terms of transmission time, the larger the subcarrier spacing, the smaller the symbol length in the time domain. The resulting smaller time slot length is more conducive to supporting ultra-low latency services such as URLLC.

[0079] In terms of cell size, the larger the CP length, the larger the cells that can be supported. This means that the smaller the subcarrier spacing, the larger the cells that can be supported. The term "cell" refers to the area covered by a single base station associated with mobile communication.

[0080] Subcarrier spacing and CP length are essential information for OFDM transmission / reception, and effective transmission / reception is only possible when the base station and UE recognize these values ​​as mutually shared. Table 1 lists the subcarrier spacing configurations (μ) and subcarrier spacing (μ) supported in 5G systems. The relationship between ) and CP length.

[0081] [Table 1]

[0082]

[0083] Table 2 lists the number of symbols per slot for each subcarrier spacing configuration (μ) under normal CP conditions. ), number of time slots per frame ( ), and the number of time slots in each subframe ( ).

[0084] [Table 2]

[0085]

[0086] Table 3 lists the number of symbols per slot for each subcarrier spacing configuration (μ) in the case of extended CP. ), number of time slots per frame ( ), and the number of time slots in each subframe ( ).

[0087] [Table 3]

[0088]

[0089] In its initial phase, the 5G system is expected to coexist with, or operate in dual mode with, legacy LTE and / or LTE-A (hereinafter referred to as LTE / LTE-A) systems. Therefore, legacy LTE / LTE-A can provide stable system operation for the UE, while the 5G system can provide improved service for the UE. Consequently, the frame structure of the 5G system needs to include at least the LTE / LTE-A frame structure or a necessary parameter set (subcarrier spacing = 15kHz).

[0090] For example, a comparison between a frame structure with a subcarrier spacing configuration of μ = 0 (hereinafter referred to as frame structure A) and a frame structure with a subcarrier spacing configuration of μ = 1 (hereinafter referred to as frame structure B) shows that, compared to frame structure A, frame structure B has twice the subcarrier spacing and RB size, and half the slot length and symbol length. In the case of frame structure B, two slots can constitute a subframe, and 20 subframes can constitute a frame.

[0091] To summarize the frame structure of a 5G system, for each frame structure, the subcarrier spacing, CP length, time slot length, etc. (basic parameter set) are integer multiples of each other, thus providing high scalability. Furthermore, subframes with a fixed length of approximately 1 millisecond can be defined to express a reference time unit independent of the frame structure.

[0092] The frame structure of a 5G system can be applied to various scenarios. Regarding cell size, a larger CP length allows for the support of larger cells, meaning frame structure A can support larger cells than frame structure B. Regarding operating frequency band, a larger subcarrier spacing is more conducive to high-frequency phase noise recovery, meaning frame structure B can support higher operating frequencies than frame structure A. Regarding service, a smaller time slot length (the basic time unit for scheduling) is more conducive to supporting ultra-low latency services (e.g., URLLC). Therefore, frame structure B may be more suitable for URLLC services than frame structure A.

[0093] As used in the following description of this disclosure, uplink (UL) can refer to a radio link through which a user equipment transmits data or control signals to a base station, and downlink (DL) can refer to a radio link through which a base station transmits data or control signals to a UE.

[0094] During the initial access procedure when a user equipment (UE) first connects to the system, the UE can perform downlink time-domain and frequency-domain synchronization and obtain the cell identifier (ID) from the synchronization signal transmitted by the base station through cell search. Furthermore, the UE can use the obtained cell ID to receive the Physical Broadcast Channel (PBCH) and obtain the MIB (System Information Block) from the PBCH as mandatory system information. Additionally, the UE can receive System Information (SI) (or System Information Block (SIB)) transmitted by the base station to obtain control information related to common transmission and reception of the cell. This control information may include random access control information, paging control information, and common control information for various physical channels.

[0095] The synchronization signal is used as a reference signal for cell search, and for each frequency band, a subcarrier spacing suitable for the channel environment, such as phase noise, can be applied. For data channels or control channels, in order to support the various services described above, different subcarrier spacings can be applied depending on the service type.

[0096] Figure 2 An example of time-domain mapping structure and beam scanning operation in a 5G system is shown.

[0097] For descriptive purposes, the following elements may be defined.

[0098] - Master Synchronization Signal (PSS): The PSS is a signal used as a reference for DL ​​time / frequency synchronization and provides some cell ID information.

[0099] - Auxiliary Synchronization Signal (SSS): The SSS serves as a reference for DL ​​time / frequency synchronization and provides another part of the cell ID information. Additionally, the SSS can be used as a reference signal for PBCH demodulation.

[0100] - PBCH: Provides the MIB, which is mandatory system information required for the UE to transmit / receive data and control channels. The MIB may include search space-related control information indicating radio resource mapping information for control channels, scheduling control information for separate data channels used for the transmission of system information, system frame number (SFN) as a frame unit index used as a timing reference, and other information.

[0101] - Synchronization Signal / PBCH Block (SS / PBCH Block) or SSB: An SS / PBCH block consists of N OFDM symbols and is configured by a combination of PSS, SSS, PBCH, etc. For systems using beam scanning technology, the SS / PBCH block is the smallest unit for beam scanning. In 5G systems, N=4 can be satisfied. 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 milliseconds). Furthermore, the L SS / PBCH blocks repeat periodically at a predetermined period P. The base station can notify the user equipment of the period P via signaling. If there is no separate signaling for the period P, the user equipment can apply a previously agreed default value. Each SS / PBCH block has an SS / PBCH block index ranging from 0 to a maximum of L-1, and the user equipment can know the SS / PBCH block index through SS / PBCH detection.

[0102] refer to Figure 2 , Figure 2 An example of applying beam scanning over time in units of SS / PBCH blocks is shown. Figure 2In the example, UE 1 205 receives the SS / PBCH block using a beam transmitted in direction #d0 203 by applying beamforming to SS / PBCH block #0 at time t1 201. Similarly, UE 2 206 receives the SS / PBCH block using a beam transmitted in direction #d4 204 by applying beamforming to SS / PBCH block #4 at time t2 202. The UE can obtain the optimal synchronization signal from the base station via the beam transmitted in the direction in which the UE is located. For example, UE 1 205 might have difficulty obtaining time / frequency synchronization and mandatory system information from the SS / PBCH block using a beam transmitted in direction #d4 from a location far from UE 1.

[0103] In addition to the initial access procedure, the UE can also receive SS / PBCH blocks to determine whether the radio link quality of the current cell remains at a specific level or higher. Furthermore, during the handover process where the UE moves access from the current cell to a neighboring cell, the UE can 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.

[0104] After obtaining the MIB and system information from the base station through the initial access procedure, the UE can perform a random access procedure to switch the link to the base station to the connected state (or RRC_CONNECTED state). Upon completion of the random access procedure, the UE switches to the connected state, in which one-to-one communication between the base station and the UE is possible. References will be made below. Figure 3 Describe the random access process in detail.

[0105] Figure 3 An example of a random access procedure in a 5G system is shown. Figure 3 Only an example of a random access procedure has been shown, and this disclosure is not limited thereto. Furthermore, this disclosure is not limited to... Figure 3 The illustrated 4-step random access procedure can also be applied to a 2-step random access procedure (sending / receiving message A (including messages corresponding to messages 1 and 3) and sending / receiving message B (including messages corresponding to messages 2 and 4)).

[0106] refer to Figure 3In the first step 310 of the random access procedure, the UE sends a random access preamble to the base station (gNB). The random access preamble is the initial message sent by the UE during the random access procedure and can be referred to as message 1. The gNB can measure the transmission delay between the UE and the gNB based on the random access preamble and can perform uplink synchronization. The UE can arbitrarily select which random access preamble to use from a set of random access preambles pre-given by system information. Furthermore, the initial transmission power of the random access preamble can be determined based on the path loss between the gNB and the UE measured by the UE. Additionally, the UE can determine the transmission beam direction of the random access preamble based on the synchronization signal received from the gNB, thereby transmitting the random access preamble.

[0107] In the second step 320, the gNB sends an uplink transmission timing adjustment command to the UE based on the transmission delay value measured from the random access preamble received in the first step 310. Additionally, the gNB may send power control commands and uplink resources to be used by the UE as scheduling information. The scheduling information may include control information regarding the UE's uplink transmission beam.

[0108] If, in step 320, the UE fails to receive a Random Access Response (RAR) (or message 2) as scheduling information regarding message 3 from the gNB within a predetermined time, the UE may execute step 310 again. When executing step 310 again, the UE may send a random access preamble after increasing its transmission power by a predetermined step (power boost), thereby increasing the probability that the gNB will receive the random access preamble.

[0109] In the third step 330, the UE uses the uplink resources allocated in the second step 320 to send uplink data (message 3) including the UE's ID to the gNB via the Physical Uplink Shared Channel (PUSCH). The timing of the PUSCH used to send message 3 can follow the timing control command received from the gNB in ​​the second step 320. Furthermore, the transmission power of the PUSCH used to send message 3 can be determined by considering the power control command received from the gNB in ​​the second step 320 and the power boost value of the random access preamble. The PUSCH used to send message 3 can refer to the uplink data signal initially sent by the UE to the gNB after the UE has already sent the random access preamble.

[0110] In step 340, after determining that the UE has performed random access without conflicting with other UEs, the gNB can send data (message 4) to the corresponding UE, including the ID of the UE that has already sent uplink data in step 330. When the UE receives the signal sent by the gNB in ​​step 340, it can confirm that the random access was successful. Furthermore, the UE can send HARQ-ACK information to the gNB via the Physical Uplink Control Channel (PUCCH) to indicate whether message 4 was successfully received.

[0111] If the gNB fails to receive a data signal from the UE due to a conflict between data transmitted by the UE in step 330 and data from another UE, the gNB may stop transmitting data to the UE. Therefore, if the UE fails to receive data transmitted from the gNB in ​​step 340 within the predetermined time, the UE may confirm that the random access procedure has failed and may restart from step 310.

[0112] Upon successful completion of the random access procedure, the UE is switched to the connected state, and one-to-one communication between the gNB and the UE becomes possible. The gNB can receive UE capability information reported by the UE in the connected state and can adjust scheduling based on this information. The UE can use its capability information to inform the gNB whether it supports specific functions, the maximum allowed values ​​for those functions, etc. Therefore, the UE capability information reported by each UE to the gNB may have different values ​​for each UE.

[0113] Figure 4 This illustrates an example of the process by which a UE reports its capability information to a base station in a 5G system.

[0114] refer to Figure 4 In step 410, the base station (gNB) 402 may send a UE capability information request message to the UE 401. In step 420, in response to the UE capability information request from the gNB, the UE sends UE capability information to the gNB.

[0115] As an example of UE capability information, a UE may report UE capability information to the gNB that includes at least a portion of the following control information.

[0116] - Control information regarding the frequency bands supported by the UE

[0117] - Control information regarding the channel bandwidth supported by the UE

[0118] - Control information regarding the maximum modulation scheme supported by the UE

[0119] - Control information regarding the maximum number of beams supported by the UE

[0120] - Control information regarding the maximum number of layers supported by the UE

[0121] - Control information regarding UE-supported CSI reporting

[0122] - Control information regarding whether the UE supports frequency hopping

[0123] - When carrier aggregation (CA) is supported, control information regarding bandwidth.

[0124] - Control information regarding whether cross-carrier scheduling is supported when CA is supported.

[0125] Next, we will describe downlink control information (DCI) in a 5G system in detail.

[0126] In 5G systems, scheduling information for uplink data (or Physical Uplink Shared Channel (PUSCH)) or downlink data (or Physical Downlink Shared Channel (PDSCH)) can be transmitted from the gNB to the UE via DCI. For PUSCH or PDSCH, the UE can monitor both the fallback DCI format and the non-fallback DCI format. The fallback DCI format may include predefined fixed fields between the base station and the UE, while the non-fallback DCI format may include configurable fields.

[0127] After channel coding and modulation, the DCI message can be transmitted via the Physical Downlink Control Channel (PDCCH). Cyclic Redundancy Check (CRC) can be appended to the payload of the DCI message, and the CRC can be scrambled by a Radio Network Temporary Identifier (RNTI) corresponding to the UE's identifier. Different RNTIs can be used depending on the purpose of the DCI message, such as UE-specific data transmission, power control commands, or random access responses. That is, the RNTI is not explicitly transmitted but is included in the CRC calculation process. When a DCI message is received via the PDCCH, the UE can identify the CRC using the assigned RNTI, and if the CRC identification result is correct, the UE knows that the corresponding message has been sent.

[0128] For example, the DCI used for scheduling PDSCH about system information can be scrambled by SI-RNTI. The DCI used for scheduling PDSCH about RAR messages can be scrambled by RA-RNTI. The DCI used for scheduling PDSCH about paging messages can be scrambled by P-RNTI. The DCI used for notifying Slot Format Indicator (SFI) can be scrambled by SFI-RNTI. The DCI used for notifying Transmit Power Control (TPC) can be scrambled by TPC-RNTI. The DCI used for scheduling UE-specific PDSCH or PUSCH can be scrambled by Cell RNTI (C-RNTI).

[0129] Regarding the UE to be scheduled, the gNB can apply and operate a predetermined DCI format based on whether the scheduling information is related to downlink data (downlink allocation), whether the scheduling information is related to uplink data (uplink grant), and whether the DCI is used for purposes other than data scheduling (such as power control).

[0130] The gNB can transmit downlink data to the UE via the PDSCH, which is the physical channel used for downlink data transmission. Detailed mapping positions in the time and frequency domains of the PDSCH, modulation schemes, HARQ-related control information, and power control scheduling information can be provided from the gNB to the UE via the DCI (Distributed Control Information Channel) related to downlink data scheduling information transmitted via the PDCCH.

[0131] The gNB can transmit uplink data to the UE via the PDSCH, which is the physical channel used for uplink data transmission. Detailed mapping locations in the time and frequency domains of the PUSCH, modulation schemes, HARQ-related control information, and power control information can be provided from the gNB to the UE via the DCI (Distributed Control Information Channel) related to uplink data scheduling information transmitted via the PDCCH.

[0132] The time-frequency resources mapped to the PDCCH are called control resource sets (CORESETs). A CORESET can be configured in the frequency domain with all or part of the frequency resources within the bandwidth supported by the UE. A CORESET can be configured with one or more OFDM symbols in the time domain, and this can be defined as the duration of the control resource set (CORESET). The base station can configure one or more CORESETs for the UE via higher-layer signaling (e.g., system information, MIB, or RRC signaling). Configuring a CORESET for the UE may mean providing it with information such as the CORESET identifier, the frequency location of the CORESET, and the symbol length of the CORESET. The information provided to the UE by the gNB to configure a CORESET may include at least some of the information included in [Table 4].

[0133] [Table 4]

[0134]

[0135]

[0136] CORESET can be determined in the frequency domain by Each RB is configured, and in the time domain it can be configured by The PDCCH can be configured with ∈{1,2,3} symbols. It can be configured by one or more Control Channel Elements (CCEs). A CCE can be configured by six Resource Groups (REGs), and each REG can be defined as a Resource Block (RB) during an OFDM symbol period. Within a CoreSet, REGs can be indexed in time priority order, starting from REG index 0, from the lowest RB of the first OFDM in the CoreSet.

[0137] As a PDCCH-related transmission method, interleaved and non-interleaved types can be supported. The base station can configure the UE for each CORESET whether to perform interleaved or non-interleaved transmission via higher-layer signaling. Interleaving can be performed on a REG bundle basis. A REG bundle can be defined as a single REG or a group of multiple REGs. The UE can determine the CCE-to-REG type in the corresponding CORESET based on the base station's configuration regarding whether the transmission is interleaved or non-interleaved, as shown in Table 5 below.

[0138] [Table 5]

[0139]

[0140] The base station can provide the UE with configuration information such as which symbol the PDCCH is mapped to in the time slot and the transmission period through signaling.

[0141] The search space for the PDCCH is described below. Depending on the aggregation level (AL), the number of CCEs required to transmit the PDCCH can be 1, 2, 4, 8, or 16, and different numbers of CCEs can be used to implement link adaptation of the downlink control channel. For example, in the case of AL = 1, a downlink control channel can be transmitted using L CCEs. The UE performs blind decoding to detect signals when there is no information about the downlink control channel; for this purpose, a search space indicating the set of CCEs can be defined. The search space is a set of downlink control channel candidates, including the CCEs that the UE needs to attempt to decode for a given AL, and since 1, 2, 4, 8, or 16 CCEs can form a bundle across various ALs, the UE can have multiple search spaces. The set of search spaces can be defined as a set of search spaces across all configured aggregation levels.

[0142] The search space can be divided into the common search space (CSS) and the UE-specific search space (USS). A group of UEs or all UEs can search the common search space of the PDCCH to receive cell common control information, such as dynamic scheduling of system information or paging messages. For example, a UE can search the common search space of the PDCCH to receive PDSCH scheduling allocation information for receiving system information. In the case of the common search space, a group of UEs or all UEs need to receive the PDCCH, so the common search space can be defined as a predetermined set of CCEs. Scheduling allocation information for UE-specific PDSCH or PUSCH can be received by searching the PDCCH in the UE-specific search space. The UE-specific search space can be defined specifically for each UE as a function of various system parameters and the UE's identifier (ID).

[0143] The configuration information for the PDCCH search space can be configured by the base station for the UE via higher-layer signaling (e.g., SIB, MIB, or RRC signaling). For example, the base station can provide the UE with configurations such as the number of PDCCH candidates at each aggregation level L, the monitoring period for the search space, the monitoring opportunities for each symbol in the time slot, the search space type (common search space or UE-specific search space), the combination of RNTI and DCI formats to be monitored in the corresponding search space, and the control resource set index used for monitoring the search space. For example, the parameters for the PDCCH search space may include the information given in Table 6 below.

[0144] [Table 6]

[0145]

[0146]

[0147]

[0148] Based on the configuration information, the base station can configure one or more search space sets for the UE. According to some embodiments, the base station can configure search space set 1 and search space set 2 for the UE. In search space set 1, the UE can be configured to monitor DCI format A scrambled by X-RNTI in a common search space, and in search space set 3, the UE can be configured to monitor DCI format B scrambled by Y-RNTI in a UE-specific search space.

[0149] According to the configuration information, one or more search space sets can exist in a public search space or a UE-specific search space. For example, search space set #1 and search space set #2 can be configured as a public search space, while search space set #3 and search space set #4 can be configured as UE-specific search spaces.

[0150] In the public search space, the UE can monitor the combinations of DCI format and RNTI given below. Obviously, the examples given below are not limiting.

[0151] - DCI format 0_0 / 1_0, CRC scrambling is done by C-RNTI, CS-RNTI, SP-CSI-RNTI, RA-RNTI, TC-RNTI, P-RNTI, SI-RNTI.

[0152] - DCI format 2_0, CRC scrambled by SFI-RNTI

[0153] - DCI format 2_1, CRC scrambling is done by INT-RNTI.

[0154] - DCI format 2_2, CRC is scrambled by TPC-PUSCH-RNTI and TPC-PUCCH-RNTI.

[0155] - DCI format 2_3, CRC scrambling is done by TPC-SRS-RNTI.

[0156] Within the UE-specific search space, the UE can monitor the combinations of DCI formats and RNTI given below. Clearly, the examples given below are not restrictive.

[0157] - DCI format 0_0 / 1_0, CRC scrambling is done by C-RNTI, CS-RNTI, and TC-RNTI.

[0158] - DCI format 1_0 / 1_1, CRC is scrambled by C-RNTI, CS-RNTI, and TC-RNTI.

[0159] RNTI can be defined and used as follows.

[0160] Cell RNTI (C-RNTI): Used for scheduling UE-specific PDSCH

[0161] Temporary Cell RNTI (TC-RNTI): Used for scheduling UE-specific PDSCH

[0162] Configured Scheduling RNTI (CS-RNTI): Used to schedule UE-specific PDSCHs with semi-static configuration.

[0163] Random Access RNTI (RA-RNTI): Used to schedule PDSCH during the random access step.

[0164] Paging RNTI (P-RNTI): Used to schedule the PDSCH that transmits paging requests.

[0165] System Information RNTI (SI-RNTI): Used to schedule the PDSCH that transmits system information.

[0166] Interrupt RNTI (INT-RNTI): Used to indicate whether the PDSCH has been perforated.

[0167] Transmit power control for PUSCH RNTI (TPC-PUSCH-RNTI): Used to indicate power control commands regarding PUSCH.

[0168] Transmit power control for PUCCH RNTI (TPC-PUCCH-RNTI): Used to indicate power control commands regarding the PUCCH.

[0169] Transmit power control for SRS RNTI (TPC-SRS-RNTI): Used to indicate power control commands regarding the SRS.

[0170] The DCI formats listed above can follow the definitions given in Table 7 below.

[0171] [Table 7]

[0172]

[0173] In 5G, the search space of the aggregation level L, which combines the control resource set p and the search space set s, can be represented by the following Equation 1.

[0174] [Equation 1]

[0175]

[0176] - L: Aggregation Level

[0177] - Carrier index

[0178] - : The total number of CCEs existing in the control resource set p

[0179] - Time slot index

[0180] - Number of PDCCH candidates at aggregation level L

[0181] - = 0, ..., -1: PDCCH candidate index at aggregation level L

[0182] - = 0, …, -1

[0183] -

[0184] - UE identifier

[0185] In the context of public search spaces, The value can correspond to 0.

[0186] In the case of a UE-specific search space The value can correspond to a value that is changed by the UE's identifier (C-RNTI or ID configured by the base station for the UE) and time index.

[0187] The methods for measuring and reporting channel status in 5G communication systems will be described in detail below.

[0188] Channel State Information (CSI) may include the information given below.

[0189] - Channel Quality Indicator (CQI): CQI index information, including modulation scheme and coding rate that meet the predefined minimum receive error rate of PDSCH.

[0190] - Precoding Matrix Index (Precoding Matrix Indicator (PMI)): Precoding matrix indication information selected by the UE.

[0191] - Channel State Information - Reference Signal-RS (CSI-RS) Resource Indicator (CRI): CSI-RS information measured by the UE

[0192] - Rank Indicator (RI): Rank indication information selected by the UE

[0193] - Layer Indicator (LI): Indication information of the best layer in the precoding matrix reported by the UE.

[0194] - SS / PBCH Block Resource Indicator (SSBRI): SSB information measured by the UE

[0195] - L1-Reference Signal Received Power (L1-RSRP): L1-RSRP information measured by the UE.

[0196] The base station can control the time and frequency resources used for the aforementioned CSI measurements and reports of the UE.

[0197] As a CSI measurement and reporting operation, "aperiodic," "semi-persistent," and "periodic" schemes can be supported, and the base station can configure the UE to use which scheme via signaling. The semi-persistent CSI reporting method supports both "PUCCH-based semi-persistent (semi-PersistentOnPUCCH) method" and "PUSCH-based semi-persistent (semi-PersistentOnPUSCH) method." For periodic or semi-persistent CSI reporting methods, the base station can configure the PUCCH or PUSCH resources for CSI transmission to the UE via higher-layer signaling. The periodicity and slot offset of the PUCCH or PUSCH resources for CSI transmission can be given by the subcarrier spacing configuration of the uplink (UL) bandwidth portion configured for CSI reporting transmission. In the case of the aperiodic CSI reporting method, the base station can schedule the PUSCH resources for CSI transmission to the UE via L1 signaling (the aforementioned DCI format 0_1).

[0198] The UE's non-periodic CSI report can be executed using PUSCH, the periodic CSI report can be executed using PUCCH, and the semi-persistent CSI report can be executed using PUSCH when triggered or activated via DCI, and can be executed using PUCCH after activation via MACCE.

[0199] Non-periodic CSI reports can be triggered by the “CSI request” field in DCI format 0_1 ​​above, which corresponds to the scheduling DCI used for PUSCH.

[0200] In wireless communication systems, one or more distinct antenna ports (which may be replaced by one or more channels, signals, and combinations thereof, but for convenience, referred to collectively as distinct antenna ports in the following description of this disclosure) can be associated with each other through quasi-co-located (QCL) configurations as shown in Table 8 below. The TCI state is used to declare the QCL relationship between physical channel A (or the demodulation reference signal (DMRS) of the corresponding physical channel) and another RS ​​or channel B. The description that reference antenna port A (reference RS #A) and another target antenna port B (target RS #B) are quasi-co-located (QCLed) means that the UE is allowed to apply some or all of the large-scale channel parameters estimated at antenna port A to channel measurements from antenna port B. QCL may need to be associated with different parameters depending on the situation, such as 1) time tracking affected by average delay and delay spread, 2) frequency tracking affected by Doppler shift and Doppler spread, 3) radio resource management (RRM) affected by average gain, or 4) beam management (BM) affected by spatial parameters. Accordingly, four types of QCL relationships are supported in 5G systems, as shown in Table 8 below.

[0201] [Table 8]

[0202]

[0203] Spatial RX parameters can refer to some or all of a variety of parameters as a whole, such as angle of arrival (AoA), power angular spectrum (PAS) of AoA, angle of departure (AoD), PAS of AoD, transmit / receive channel correlation, transmit / receive beamforming, and spatial channel correlation.

[0204] QCL relationships can be configured for a UE using the RRC parameters TCI-state and QCL-info, as shown in Table 9 below. Referring to Table 9, the base station can configure one or more TCI states for the UE, thereby informing the UE of up to two QCL relationships (qcl-Type1, qcl-Type2) regarding the ID of the RS (i.e., the target RS) of the reference TCI state. Each QCL information (QCL-info) included in each TCI state includes the serving cell index and BWP index of the reference RS indicated by the corresponding QCL information, the type and ID of the reference RS, and the QCL type as shown in Table 8 above.

[0205] [Table 9]

[0206]

[0207] Figure 5 An example of base station beam allocation configured according to TCI status is shown.

[0208] refer to Figure 5 The base station can transmit information about N different beams to the UE through N different TCI states. For example, in... Figure 5 In the case of N=3, the base station can configure the qcl-Type2 parameter included in the three TCI states 500, 505 and 510 as QCL type D, and associate it with the CSI-RS or SSB corresponding to different beams, thereby notifying the antenna ports of the reference different TCI states 500, 505 and 510 to be associated with different spatial Rx parameters (i.e. different beams).

[0209] In the case of PDCCH demodulation reference signal (DMRS), the specific valid TCI state configurations applicable to the PDCCH DMRS antenna port are shown in Table 10 below. In Table 10, "Valid TCI state configuration = 4" is a combination assumed by the UE before RRC configuration and cannot be configured after RRC configuration.

[0210] [Table 10]

[0211]

[0212] In 5G systems, dynamic allocation of PDCCH beams supports, for example... Figure 6 The layered signaling method shown. Figure 6 An example of the PDCCH beam assignment method is shown.

[0213] refer to Figure 6 The base station can configure N TCI states 605, 610, ..., 620 for the UE via RRC signaling 600, and can configure some of them as the TCI state for CORESET (625). Subsequently, the base station can indicate one of the TCI states 630, 635, and 640 (645) for CORESET to the UE via MAC CE signaling. The UE can then receive the PDCCH based on the beam information included in the TCI state indicated by the MAC CE signaling.

[0214] Figure 7 The TCI indication MAC CE signaling structure for PDCCH DMRS is shown.

[0215] refer to Figure 7 The TCI indication MAC CE signaling used for PDCCH DMRS is configured by 2 bytes (16 bits) and includes 1 reserved bit 710, 5 serving cell ID 715, 2 BWP ID 720, 2 CORESETID 725 and 6 TCI status ID 730.

[0216] Figure 8 An example of CORESET and search space beam configuration is shown.

[0217] refer to Figure 8 The base station can indicate one of the TCI status lists (805) included in the CORESET 800 configuration via MAC CE signaling. Until different TCI statuses are subsequently indicated for the corresponding CORESET via different MAC CE signaling, the UE can assume that the same QCL information (beam #1) 805 is applied to all of one or more search spaces 810, 815 and 820 associated with the CORESET.

[0218] The problem with the aforementioned PDCCH beam assignment method is that it is difficult to indicate beam changes that occur faster than the MAC CE signaling delay, and the same beam is unilaterally applied to each CORESET regardless of search space characteristics, making flexible PDCCH beam operation difficult. In the following embodiments of this disclosure, “PDCCH QCL Determination Method 1,” “PDCCH QCL Determination Method 2,” and “PDCCH QCL Determination Method 3” are provided as more flexible PDCCH beam configuration and operation methods. Although several different examples will be provided for the sake of describing embodiments of this disclosure, they are not mutually exclusive and can be appropriately combined and applied for each situation.

[0219] PDCCH QCL Determination Method 1

[0220] The base station can configure one or more TCI states for a UE for a specific control resource set, and can activate one of the configured TCI states via a MAC CE activation command. For example, if {TCI state #0, TCI state #1, TCI state #2} are configured as TCI states for control resource set #1, the base station can send an activation command to the UE via MAC CE, causing TCI state #0 to be assumed to be a TCI state for control resource set #1. In other words, based on the activation command for the TCI state received via MAC CE, and based on the QCL information in the activated TCI state, the UE can correctly receive the DMRS for the corresponding CORESET.

[0221] PDCCH QCL Determination Method 2

[0222] Regarding the control resource set configured with index 0 (control resource set #0), if the UE fails to receive a MAC CE activation command regarding the TCI state of control resource set #0, the UE may assume that the DMRS sent in CORESET #0 is quasi-co-located with the SS / PBCH block identified during the initial access procedure or during a contention-free random access procedure not triggered by a PDCCH command.

[0223] PDCCH QCL Determination Method 3

[0224] Regarding control resource sets (CORESET#X) configured with index values ​​other than 0, if the UE has not configured a TCI state for CORESET#X, or if the UE has configured one or more TCI states but has failed to receive a MAC CE activation command to activate one of them, the UE may assume that the DMRS sent in CORESET#X is quasi-co-addressable with the SS / PBCH block identified during the initial access procedure.

[0225] Base station energy-saving methods will be described below. As a way to support ultra-high-speed data services, spatial multiplexing using multiple transmit / receive antennas can improve data rates. Typically, the number of power amplifiers (PAs) required increases proportionally to the number of transmit / receive antennas provided in the base station or UE. The maximum output of the base station and UE depends on the PA characteristics, and the maximum output of the base station typically varies depending on the size of the cell it covers. Maximum output is typically expressed in dBm. The maximum output of the UE is typically 23 dBm or 26 dBm.

[0226] As an example of a commercial 5G base station, a base station can be equipped with 64 transmit antennas and 64 corresponding power amplifiers (PAs) in the 3.5 GHz band, and can operate with a bandwidth of 100 MHz. Therefore, the power consumption of the base station increases proportionally to the output and operating time of the power amplifiers. Compared to LTE base stations, 5G base stations are characterized by using a larger bandwidth due to their higher operating frequency band and having more transmit antennas. This characteristic is effective in increasing data rates, but at the cost of increased base station energy consumption. Therefore, the energy consumed by the entire mobile communication network increases proportionally to the number of base stations constituting the mobile communication network.

[0227] As mentioned above, the energy consumption of a base station is highly dependent on the operation of the power amplifier. Since the power amplifier participates in the base station's transmission operations, the downlink transmission of the base station is highly correlated with its energy consumption. In contrast, the uplink reception operations of the base station do not account for the majority of its energy consumption. The physical channels and physical signals transmitted by the base station in the downlink are as follows.

[0228] - PDSCH: Downlink Data Channel, which includes data to be sent to one or more UEs.

[0229] - PDCCH: Downlink control channel, including scheduling information about PDSCH and PUSCH. Alternatively, the base station can send control information, such as slot format and power control commands, only through PDCCH without scheduling PDSCH or PUSCH. Scheduling information includes information about the resources mapped to PDSCH or PUSCH, HARQ-related information, power control information, etc.

[0230] - PBCH: Downlink Broadcast Channel, used to provide the MIB with the mandatory system information required by the UE for transmitting / receiving data and control channels.

[0231] - PSS: A signal that serves as a reference for DL ​​time / frequency synchronization and provides partial information about the cell ID.

[0232] - SSS: A signal used as a reference for DL ​​time / frequency synchronization and providing residual information about the cell ID.

[0233] - DM-RS: Reference signal used by the UE for channel estimation for each of PDSCH, PDCCH and PBCH.

[0234] - CSI-RS: Downlink signal, used as a reference for downlink channel state measurement of the UE.

[0235] - Phase Tracking Reference Signal (PT-RS): A downlink signal used for phase tracking.

[0236] Regarding base station energy saving, if the base station stops downlink transmission operations, the power amplifier operation also stops accordingly, which increases the base station's energy-saving effect. This not only reduces the operation of the power amplifier but also reduces the operation of other base station equipment such as baseband devices, achieving additional energy savings. Similarly, if uplink reception operations can be stopped, even if uplink reception operations account for a relatively small proportion of the base station's overall energy consumption, additional energy savings can be achieved.

[0237] The downlink transmission operations of a base station are largely dependent on downlink traffic volume. For example, if there is no data to be sent to the UE in the downlink, the base station does not need to send PDSCH and PDCCH for scheduling PDSCH. Alternatively, if for some reason, such as the data being insensitive to transmission delay and the transmission being able to pause briefly, the base station may not send PDSCH and / or PDCCH. In the following text, for ease of description, the method described above for reducing base station energy consumption by not sending PDSCH and / or PDCCH related to data services or by appropriately adjusting transmission will be referred to as "Base Station Energy Saving Method 1-1".

[0238] Conversely, physical channels and physical signals such as PSS, SSS, PBCH, and CSI-RS are characterized by being repeatedly transmitted at pre-arranged periods, regardless of UE data transmission. Therefore, even without receiving data, the UE can continuously update downlink time / frequency synchronization, downlink channel state, radio link quality, etc. In other words, PSS, SSS, PBCH, and CSI-RS need to be transmitted via the downlink, regardless of downlink data traffic volume, leading to energy consumption by the base station. Therefore, base station energy saving (hereinafter referred to as "Base Station Energy Saving Method 1-2") can be achieved by controlling the transmission of PSS, SSS, PBCH, and CSI-RS signals, which are unrelated to (or have low correlation with) data traffic volume, to occur less frequently.

[0239] By using "Base Station Energy Saving Method 1-1" or "Base Station Energy Saving Method 1-2", base station energy saving can be maximized by stopping or minimizing the operation of power amplifiers and related RF equipment, baseband equipment, etc., during the time interval when the base station does not perform downlink operations.

[0240] As another approach, the energy consumption of a base station can be reduced by turning off some of its antennas or power amplifiers (hereinafter referred to as "Base Station Energy Saving Method 2"). In this case, the energy-saving effect of the base station may involve adverse effects, such as reduced cell coverage or reduced throughput. For example, as mentioned above, a base station may be equipped with 64 transmit antennas and corresponding 64 power amplifiers, and operates in the 3.5 GHz band with a bandwidth of 100 MHz. If the base station activates only 4 transmit antennas and 4 power amplifiers at predetermined time intervals and turns off the other transmit antennas and power amplifiers to save base station energy, the base station energy consumption during that time interval will be reduced by approximately 1 / 16 (=4 / 64). However, when only 4 transmit antennas and 4 power amplifiers are activated during that time interval while the other transmit antennas and power amplifiers are turned off, it is difficult to achieve the same cell coverage and throughput as when assuming 64 antennas and power amplifiers, due to the reduction in maximum transmission power and beamforming gain.

[0241] In the following description, to distinguish it from normal base station operation, the base station mode in which base station power saving is applied will be referred to as base station power saving (ES) mode, and the base station mode in which normal base station operation is applied will be referred to as base station normal mode.

[0242] As an alternative solution to support ultra-high-speed data services, 5G systems can support signal transmission / reception over ultra-wide bandwidths (tens of MHz to hundreds of MHz, or even several GHz). This can be achieved using a single component carrier (CC) or carrier aggregation (CA) technology, which combines multiple CCs. When mobile operators cannot guarantee sufficient frequency bandwidth to provide ultra-high-speed data services using a single component carrier, CA technology can increase the total frequency bandwidth by combining each component carrier, which has a relatively small bandwidth, thus enabling ultra-high-speed data services.

[0243] Generally, the lower the frequency band, the lower the path loss, and therefore the larger the coverage area; conversely, the higher the frequency band, the higher the path loss, and therefore the smaller the coverage area. In low-frequency bands, fewer frequencies are available for mobile communication, resulting in smaller bandwidth. On the other hand, in high-frequency bands, it is easier to secure wideband frequencies, which is also applicable to ultra-fast data services. The development of mobile communication systems has always been accompanied by efforts to discover and utilize new frequency bands. For example, in next-generation (sixth generation (6G)) mobile communication systems, the terahertz (THz) (10¹² Hz) band is considered one of the candidate frequencies, although it is still in the early stages of discussion.

[0244] Typically, mobile operators secure multiple frequency bands and provide mobile communication services to users. For example, a mobile operator can combine already secured LTE system frequency bands with newly secured 5G system frequency bands to operate a combined LTE and 5G system. As another example, a mobile operator can secure multiple 5G system frequency bands and then combine these bands to provide mobile communication services via 5G CA (Cybernetic Access Control). As mentioned above, characteristics such as coverage and bandwidth vary depending on the frequency band, and mobile communication services based on combinations of multiple frequency bands are surpassing those based on a single frequency band.

[0245] Figure 9 This is a schematic diagram illustrating an example of configuring a 5G system by combining three component carriers for each combination in the uplink and downlink.

[0246] according to Figure 9 In carrier aggregation systems, component carriers are classified as PCells or SCells for operation. The primary cell (PCell), or first cell, provides basic radio resources to the UE and serves as a reference cell for operations such as initial access and handover. The PCell is configured with a downlink primary frequency (or primary component carrier (PCC)) and an uplink primary frequency. The UE can transmit uplink control information (UCI) via the PUCCH, which serves as the uplink control channel. This uplink control information includes HARQ ACK / NACK for feedback on whether there are errors in the data received from the base station, CSI indicating the channel state between the base station and the UE, etc., and can be transmitted via the PCell. The secondary cell (SCell), or second cell, provides additional radio resources to the UE along with the PCell and can be configured with a downlink secondary frequency (or secondary component carrier (SCC)) and an uplink secondary frequency, or can be configured with only a downlink secondary frequency.

[0247] The configuration of each component carrier is independent of each other, and downlink carrier aggregation and uplink carrier aggregation can be applied independently of each other. For example, carrier aggregation including one component carrier with a bandwidth of 100 MHz and two component carriers with a bandwidth of 50 MHz can be applied to the downlink, and only one component carrier with a bandwidth of 100 MHz can be used for the uplink (i.e., carrier aggregation may not be applied). In this disclosure, unless otherwise stated, cells and component carriers are used interchangeably without distinction. The base station can notify the UE via signaling about the configuration of carrier aggregation, such as which component carriers to combine, the number of component carriers to combine, and control information related to the bandwidth of each component carrier.

[0248] As described above, in systems employing carrier aggregation (CA) technology that combines multiple component carriers, the transmission of SSBs in predetermined component carriers can be reduced to decrease base station energy consumption. In other words, the base station can reduce base station energy consumption for SSB transmission by omitting SSB transmissions or making SSB transmissions less frequent. However, in this case, it is necessary to replace or supplement methods that already provide functions (such as time-frequency synchronization, QCL or beam management (BM), uplink transmission power reference signals, etc.) to the UE via SSB transmission by the base station.

[0249] In the following detailed embodiments, a method for reducing base station energy consumption by reducing SSB transmission according to the present disclosure will be described. Various examples will be described in the following description of this disclosure through multiple embodiments; however, these embodiments are not independent embodiments, and one or more embodiments may be applied simultaneously or in combination.

[0250] <First Embodiment>

[0251] The first embodiment describes a method in which the UE determines the QCL of a cell in which the base station reduces SSB transmissions to reduce base station energy consumption.

[0252] Specifically, the first embodiment relates to a method in which the UE determines the QCL of the PDCCH when SSB transmissions of the SCell are reduced to decrease base station energy consumption in a system applying carrier aggregation. To reduce SSB transmissions and thus decrease base station energy consumption, the base station may omit SSB transmissions of the SCell or perform SSB transmissions infrequently. For convenience in the following description, the SCell described above may be referred to as an "SSB-free SCell".

[0253] According to the above-described PDCCH (or PDCCH DMRS) QCL determination method ("PDCCH QCL Determination Method 2" or "PDCCH QCL Determination Method 3"), when the UE does not receive a MAC CE activation command for the TCI state of the SCell from the base station, the UE determines that the PDCCH DMRS of the SCell is quasi-co-located with the SSB identified during the UE's initial access procedure or a contention-free random access procedure not triggered by a PDCCH command. However, in the first embodiment, due to the reduction in SSB transmissions, there may be no SSB as a reference for the QCL of the PDCCH DMRS of the "SCell without an SSB," or even if there is, its accuracy cannot be guaranteed.

[0254] To address the aforementioned issues, besides SSB-free SCells where SSB transmission is reduced, the base station can designate a "reference cell," which is a reference for the QCL of the PDCCH DMRS, and notify the UE of this via signaling. Furthermore, the base station can inform the UE of the reference signals (RS) that the UE needs to reference in the "reference cell." The RS can be an SSB or a CSI-RS. The "reference cell" can be a PCell or a second SCell in a carrier aggregation cell that does not include the SSB-free SCell. For example, the signaling can be higher-layer signaling and can indicate an SSB index or a CSI-RS resource index to indicate the RS.

[0255] Figure 10 This is a schematic diagram illustrating an example of a method for determining the QCL of a UE when the UE has not received a MACCE activation command for the TCI state of the SCell from the base station, according to the first embodiment. Although not shown, when the UE receives a MAC CE activation command for the TCI state of the SCell from the base station, the UE can determine the QCL of the PDCCH DMRS according to the "PDCCH QCL Determination Method 1" described above.

[0256] In operation 1010, the UE determines whether the PDCCH to be received is transmitted in a "SCell without SSB". When the PDCCH is transmitted in a "SCell without SSB", in operation 1030, the UE determines that the RS of the "reference cell" notified to the UE by the base station via signaling is quasi-co-located with the corresponding PDCCH DMRS. The RS of the "reference cell" can be an SSB or a CSI-RS, and can be notified to the UE by the base station via signaling. The UE can receive the PDCCH based on the determined QCL relationship.

[0257] When the SCell transmitting the PDCCH to be received by the UE is not an "SSB-free SCell", in operation 1020, the UE determines that the PDCCH DMRS of the corresponding SCell is quasi-co-located with the SSB identified during the UE's initial access procedure or during a non-contention-based random access procedure not triggered by a PDCCH command. This is the same as "PDCCH QCL determination method 2" or "PDCCH QCL determination method 3" described above. The UE can receive the PDCCH based on the determined QCL relationship.

[0258] The flowcharts above illustrate exemplary methods that can be implemented according to the principles of this disclosure, and various modifications can be made to the methods shown in the flowcharts of the specification. For example, although the diagrams depict a series of operations, the various operations in each figure can overlap, operate in parallel, operate in different orders, or operate multiple times. In another example, operations can be omitted or replaced with other operations.

[0259] When the base station sends PDSCH to the UE in the SCell, the UE can correctly receive the PDSCH based on the QCL information in the TCI state of the PDSCH activated by the MAC CE activation command for the PDSCH QCL. When the UE does not receive the MAC CE activation command for the PDSCH QCL or the MAC CE activation command is invalid, the UE can determine that the QCL of the PDSCH is the same as the QCL of the PDCCH. Therefore, by combining the UE's PDCCH QCL determination method in operation 1030, the UE can determine that the PDSCH DMRS and PDCCH DMRS are quasi-co-located, and that the PDCCH DMRS and the RS of the "reference cell" are quasi-co-located. Thus, the UE can determine that the PDSCH DMRS and the RS of the "reference cell" are quasi-co-located. In this case, the UE can receive the PDSCH based on the determined QCL relationship.

[0260] <Second Embodiment>

[0261] The second embodiment describes a method for signaling the reduction of SSB transmission to the UE when the base station reduces SSB transmission in a predetermined cell to reduce base station energy consumption.

[0262] Specifically, the second embodiment describes a method in which the base station notifies the UE of the reduced SSB transmission of the SCell (“SCell without SSB”) when the base station reduces SSB transmission of the SCell to reduce base station energy consumption in a system applying carrier aggregation.

[0263] The SSB configuration information associated with the SSB transmitted in the predetermined cell may include the following. The base station may notify the UE of the SSB configuration information via higher-layer signaling.

[0264] - absoluteFrequencySSB: Information indicating the mapping location of the SSB in the frequency domain.

[0265] - ssb-PositionsInBurst: Information indicating the mapping position of the SSB in the time domain. For example, a bitmap scheme can be used to indicate whether the actual SSB is mapped to a pre-agreed mapping position in the time domain. For example, by associating an 8-bit bitmap including b1 to b8 with eight pre-agreed time domain positions of the SSB (b1: SSB1, b2: SSB2, ... b8: SSB8), it can indicate that when the corresponding bit is "1", the SSB was actually transmitted at the corresponding time domain position, and when the corresponding bit is "0", the SSB was not actually transmitted at the corresponding time domain position.

[0266] - ssb-periodicityServingCell: Information indicating the transmission period of the SSB. It can be expressed in milliseconds and can be configured to a value such as 5 milliseconds, 10 milliseconds, 20 milliseconds, 40 milliseconds, 80 milliseconds, and 160 milliseconds.

[0267] - ss-PBCH-BlockPower: Information indicating the Energy Per Resource Element (EPRE), which indicates the transmission power of the secondary synchronization signal (SSS) of the SSB. It can be expressed in dBm. For example, it can be configured to a value in the range of -60 dBm to 50 dBm. For PSS EPRE, PBCH EPRE, and PBCH DMRS EPRE, the same value as SSS EPRE is typically used.

[0268] When a base station omits SSB transmission for SCell operations without an SSB, the base station can notify the UE of the omission of SSB transmission by not signaling at least one piece of SSB configuration information to the UE. Therefore, when the UE does not receive SSB configuration information (or at least one of the information included in the SSB configuration information) from the base station via signaling, the UE can identify that SSB transmission has been omitted. Alternatively, the base station can configure a special state indicating that SSB transmission has been omitted as part of the SSB configuration information and notify the UE of it. For example, the omission of SSB transmission can be indicated by configuring all bits in the bitmap indicating ssb-PositionsInBurst to "0". Alternatively, the special state indicating the omission of SSB transmission can be added to ssb-periodicityServingCell or ss-PBCH-BlockPower. In other words, as an example, in the case of omitted SSB transmission, the base station can configure at least one piece of information included in the SSB configuration information to a predetermined value. Upon receiving the SSB configuration information, the UE can identify that SSB transmission has been omitted.

[0269] When a base station sends an SSB less frequently for "SCell operations without an SSB", it can add a status indicating the corresponding value to the SSB configuration information. For example, as a status added to ssb-periodicityServingCell, a value greater than the existing value can be added, such as 320 milliseconds or 540 milliseconds.

[0270] Alternatively / additionally, in addition to the SSB configuration information mentioned above, the base station may define additional signaling separately as a method to notify the UE of "SCell without SSB" operation. Therefore, when the UE receives signaling from the base station, the UE can identify that SSB transmission has been omitted in the cell corresponding to the signaling, or that the corresponding cell is operating as a "SCell without SSB" with a low SSB transmission frequency.

[0271] In the following text, reference will be made to Figure 11 The operation according to the second embodiment is described. Figure 11 This is a schematic diagram illustrating an example of operation according to the second embodiment.

[0272] refer to Figure 11In operation 1110, base station 1102 may send a UE capability information request message to UE 1101. In response to the UE capability information request from the base station, in operation 1120, the UE sends UE capability information to the base station. The UE capability information may include at least one of the following: whether the UE supports carrier aggregation, bandwidth-related control information for each component carrier when carrier aggregation is supported, whether the UE supports base station energy reduction operations, and whether the UE supports base station SSB transmission reduction operations.

[0273] In operation 1130, the UE can provide a measurement report for neighboring cells. For example, when the strength of a received signal (e.g., a reference signal) observed by the UE from a neighboring cell is greater than a predetermined threshold, the UE can include the corresponding cell ID and the strength of the received signal in the measurement report and send it to the base station. The reference signal observed by the UE for the measurement report can be an SSB or CSI-RS transmitted by the neighboring cell. The base station can notify the UE of control information for the measurement report via signaling. The control information for the UE's measurement report can include at least a portion of the following control information. The signaling can be high-level signaling.

[0274] - Information associated with the reference signal of the neighboring cell to be measured. For example, whether it is SSB or CSI-RS.

[0275] - Subcarrier spacing of the reference signal

[0276] - Location of the reference signal in the time / frequency domain

[0277] - Magnitude of the reference signal in the time / frequency domain

[0278] - When reporting measurement results measured by the UE to the base station, is the reporting performed periodically or based on predetermined events?

[0279] The base station can determine whether to configure carrier aggregation for the UE or instruct it to switch to another cell by referring to the UE's measurement report, UE capability information, etc. Determining whether to configure carrier aggregation may, for example, involve determining whether to combine an additional carrier (SCell) with the current UE's PCell.

[0280] When the base station determines to apply carrier aggregation and SSB-free SCell operations to the UE, in operation 1140, the base station may include the relevant information required for the UE's SCell combination in an "RRC Reconfiguration" message and send it to the UE. This is referred to as the "SCell Add" operation. The relevant information required for carrier aggregation may include the SCell's carrier bandwidth and center frequency information, the SCell's physical channel common control information, and control information indicating that the SCell is an "SSB-free SCell" with reduced SSB transmission. The control information indicating that the SCell is an "SSB-free SCell" with reduced SSB transmission can follow the description above.

[0281] In operation 1150, the UE completes the process for performing communication with SCell based on the received "RRC reconfiguration" message, and then sends an "RRC reconfiguration complete" message to the base station to notify that the "SCell add" configuration process is complete.

[0282] In operation 1160, the base station can indicate SCell activation to a UE that has completed SCell configuration via SCell. When SCell activation is performed, the UE can monitor the PDCCH used to schedule downlink and uplink data for the corresponding SCell and perform operations such as receiving PDSCH scheduled by the PDCCH, sending PUSCH scheduled by the PDCCH, sending SRS in the uplink of the SCell, CSI reporting, and PUCCH transmission. The base station can notify the UE of the SCell activation indication (or command) via MAC signaling or physical layer signaling. By including the control information in the SCell activation command in operation 1160, instead of in the RRC reconfiguration message in operation 1140, the base station can notify the UE of control information indicating that the SCell is an "SSB-free SCell" with reduced SSB transmission. The control information included in the SCell activation command and indicating that the SCell is an "SSB-free SCell" with reduced SSB transmission can be, for example, a bit added to the SCell activation / deactivation MAC CE and indicating that each cell is an "SSB-free SCell", or it can correspond to a separate MAC CE indicating that each cell is an "SSB-free SCell".

[0283] After operation 1160, the UE is in a state where it is ready to perform data transmission / reception with both the PCell and SCell of the base station.

[0284] The flowcharts above illustrate exemplary methods that can be implemented according to the principles of this disclosure, and various modifications can be made to the methods shown in the flowcharts of this disclosure. For example, although operations are shown as a series of operations, the various operations in each figure can overlap, operate in parallel, operate in different orders, or operate multiple times. In another example, operations can be omitted or replaced with other operations.

[0285] A UE that is notified by the base station that the SCell is a "SCell without SSB" can perform QCL determination according to the first embodiment described above.

[0286] Furthermore, for SCells, SSB-based measurement reports may no longer be valid due to the potential insufficiency of the SSB. Therefore, similar to the first embodiment, the base station can notify the UE of a separate "reference cell" and / or "reference signal" for measurement reports associated with the SCell to support the UE's measurement reporting operations. For example, the base station can indicate to the UE a separate reference cell (or a reference cell and a predetermined reference signal on the reference cell) for measurement reporting, or it can indicate to the UE that measurement reporting needs to be performed based on another reference signal (e.g., CSI-RS) on the SCell.

[0287] Furthermore, typically, to determine the transmission power of an uplink signal (e.g., SRS) or uplink channel (PUCCH or PUSCH) in a predetermined cell, the UE can determine the level of path loss between the UE and the base station by referencing the received strength of the corresponding cell's SSB and apply it to uplink transmission power control. However, in the case of a "SCell without an SSB," as described above, the corresponding SSB may not exist. Therefore, the base station can determine a "reference cell" and / or "reference signal" as a reference for the UE's uplink transmission power and notify the UE of this. For example, the reference cell and / or reference signal used to determine the path loss may be the same as the reference cell and / or reference signal indicated for QCL determination in the first embodiment, or the reference cell and / or reference signal used to determine the path loss may be indicated to the UE separately from the reference cell and / or reference signal used for QCL determination. For example, the reference signal may be an SSB or CSI-RS.

[0288] <Third Embodiment>

[0289] The third embodiment describes a method for interpreting SSB configuration information when a base station omits SSB transmission in a predetermined cell to reduce base station energy consumption.

[0290] Specifically, the third embodiment describes a method for interpreting ss-PBCH-BlockPower control information when omitting SSB transmission of SCell in order to reduce base station energy consumption in a system applying carrier aggregation.

[0291] First, a method for configuring the transmission power of downlink signals in the general mode of a base station without applying base station energy consumption reduction operations will be described.

[0292] The transmitted power of a signal can be expressed as power spectral density (PSD) in conjunction with bandwidth. PSD is typically measured in watts per hertz (W / Hertz), representing the power per unit bandwidth. Transmission bandwidth refers to the bandwidth occupied by the signal transmitted by the base station and can be expressed in MHz. EPRE can be used as a concept similar to PSD. EPRE refers to the energy per RE (relay). EPRE can be expressed in dBm.

[0293] Figure 12 This is a schematic diagram illustrating an example of the EPRE configuration for downlink signals in a 5G system. The base station is basically configured with SSS EPRE 1210, adjusting CSI-RS EPRE 1220 relative to SSS EPRE, PDSCHEPRE 1230 relative to CSI-RS EPRE, and PDSCH DMRS EPRE relative to PDSCH EPRE, etc. In other words, the EPRE relationships of the downlink signals are correlated. The base station can notify the UE of the downlink signal EPRE using the following methods. The signaling used by the base station to notify the UE of the aforementioned power-related information can be higher-layer signaling or DCI.

[0294] - "ss-PBCH-BlockPower" 1215: A parameter used to adjust SSS EPRE 1210, which is provided to the UE by the base station via signaling. It is expressed in dBm. The same value as SSSEPRE applies to PSS EPRE, PBCH EPRE, and PBCH DMRS EPRE.

[0295] - "powerControlOffsetSS" 1225: A parameter used to adjust the power offset of CSI-RS relative to SSS RE, provided to the UE by the base station via signaling. This is the ratio of CSI-RS EPRE to SSS EPRE, expressed in dB. Therefore, CSI-RS EPRE 1220 = "ss-PBCH-Block Power" + "powerControlOffsetSS".

[0296] - "powerControlOffset" 1235: A parameter used to adjust the power offset of the PDSCH RE relative to the CSI-RS RE, provided to the UE by the base station via signaling. This is the ratio of PDSCH EPRE to CSI-RS EPRE, expressed in dB. Therefore, PDSCH EPRE 1230 = "ss-PBCH-BlockPower" + "powerControlOffsetSS" + "powerControlOffset".

[0297] - Ratio of PDSCH EPRE to PDSCH DMRS EPRE: The ratio of PDSCH EPRE to PDSCH DMRS EPRE is determined based on the PDSCH DMRS configuration determined individually by the base station.

[0298] When a base station omits SSB transmission for an SCell to reduce energy consumption, the "ss-PBCH-BlockPower" indicator, which shows the SSS transmission power of the SSB, becomes a value no longer related to the SSB transmission of the SCell. However, "ss-PBCH-BlockPower" can still be used as a reference for calculating the transmission power of the CSI-RS and PDSCH of the SCell.

[0299] Therefore, depending on whether the SSB transmission is omitted in the SCell, the UE's "ss-PBCH-BlockPower" operation for the SCell can be classified into the following operations.

[0300] - When the SCell's "ss-PBCH-BlockPower" is signaled and the SCell SSB transmission is not omitted: the UE recognizes that the SCell's SSB transmission is actually performed and calculates the SSB transmission power based on "ss-PBCH-BlockPower". Furthermore, the transmission power of the SCell CSI-RS or SCell PDSCH is calculated based on "ss-PBCH-BlockPower".

[0301] - When the SCell's "ss-PBCH-BlockPower" is signaled and the SCell SSB transmission is omitted: the UE recognizes that the SCell's SSB transmission was not actually performed and does not calculate the SSB transmission power. The transmission power of SCell CSI-RS and SCell PDSCH is calculated based on "ss-PBCH-BlockPower".

[0302] - If the SCell's "ss-PBCH-BlockPower" is not signaled and the SCell SSB transmission is omitted: the UE recognizes that the SCell's SSB transmission was not actually performed and does not calculate the SSS transmission power. The base station can notify the UE to use another cell outside the SCell as the "reference cell," and the UE can calculate the SCell's CSI-RS transmission power and SCell's PDSCH transmission power based on the "reference cell's" SSS transmission power.

[0303] <Fourth Embodiment>

[0304] In the fourth embodiment, when reducing SSB transmission of SCell in order to reduce base station energy consumption in a system using carrier aggregation, the maximum receive timing difference (MRTD) between downlink signals received from cell A and cell B included in the carrier aggregation is defined.

[0305] Table 11 shows the permissible tolerances for MRTD in a typical carrier aggregation environment. According to Table 11, the permissible tolerances for MRTD are defined based on the detailed conditions of the frequency band where carrier aggregation is applied.

[0306] - Frequency range 1 (FR1): Frequency range from 410 MHz to 7125 MHz, which is a relatively low frequency band compared to FR2.

[0307] - Frequency Range 2 (FR2): Frequency range from 24.25 GHz to 52.6 GHz, which is a relatively high frequency band compared to FR1.

[0308] - Between FR1 and FR2: The frequency in FR1 and the frequency in FR2 are configured as a carrier aggregation system.

[0309] - Intra-band discontinuous CA: Carrier aggregation between cells operating at discontinuous frequencies within the same frequency band. Because the channel environment differences between cells are relatively small compared to inter-band CA, a relatively small value is applied as the tolerance limit for MRTD.

[0310] - Inter-band CA: Carrier aggregation operates between cells in different frequency bands. Compared to intra-band discontinuous CA, the channel environment varies greatly between cells, therefore a relatively large value is applied as the tolerance limit for MRTD.

[0311] [Table 11]

[0312]

[0313] As described above, when reducing the SSB transmission of the SCell to reduce the base station energy consumption, in order to determine the QCL associated with the SCell or perform the measurement report associated with the SCell, the UE needs to refer to the indicated "reference cell". The "reference cell" needs to have sufficient similarity to be used as a reference for the QCL associated with the SCell or the channel state. Preferably, a relatively small value is applied as the tolerance of the MRTD. Therefore, according to the fourth embodiment, in the carrier aggregation system including the "SCell without SSB", the tolerance of the MRTD can be defined as shown in Table 12 below. According to Table 12, the tolerance of the MRTD is defined according to the detailed conditions of the frequency band to which the carrier aggregation is applied.

[0314] - FR1: The MRTD (A3) of the carrier aggregation system including the "SCell without SSB" satisfies the relationship of A1 ≤ A3 < A2.

[0315] - FR2: The MRTD (B3) of the carrier aggregation system including the "SCell without SSB" satisfies the relationship of B1 ≤ B3 < B2.

[0316] - Between FR1 and FR2: The MRTD (C3) of the carrier aggregation system including the "SCell without SSB" satisfies the relationship of C3 < C2.

[0317] That is, in the case where the CA includes the SCell without SSB, the allowable value of the MRTD can be equal to or less than the case of inter-band CA and greater than the case of intra-band CA.

[0318] [Table 12]

[0319]

[0320] Therefore, in the case of the carrier aggregation system including the "SCell without SSB", the maximum reception timing difference (MRTD) between the downlink signals received by the UE from different cells A and B respectively needs to satisfy the tolerance of Table 12. The base station does not need to configure the CA that does not satisfy the MRTD configuration, and when the CA configuration of the base station does not satisfy the MRTD configuration, the UE can determine that the CA configuration is an incorrect base station configuration and can not follow this configuration.

[0321] <Fifth Embodiment>

[0322] In the fifth embodiment, examples of the UE process and the base station process according to the preferred embodiment of the present disclosure will be described. The UE process and the base station process of the fifth embodiment can be executed in combination with at least one of the first to fourth embodiments.

[0323] Figure 13This is a schematic diagram illustrating an example of a UE process according to an embodiment of this disclosure. Specifically, Figure 13 The flowchart illustrates a process in which the UE performs corresponding operations based on the base station's configuration when the base station reduces SSB transmissions of the SCell in order to reduce energy consumption in a system using carrier aggregation.

[0324] refer to Figure 13 In operation 1301, the UE reports UE capability information to the base station, including the ability to support the base station power-saving mode. Specifically, the UE capability information may include at least one capability information related to the base station power-saving mode, such as information indicating whether the UE supports the base station power-saving mode, information indicating whether the UE supports carrier aggregation, information indicating whether the UE supports the base station's SSB transmission reduction operation, control information related to the frequency band supported by the UE, and control information related to the channel bandwidth supported by the UE.

[0325] In operation 1302, the base station can notify the UE of an "SSB-free SCell" configuration. The "SSB-free SCell" configuration may include control information indicating that the corresponding SCell is an "SSB-free SCell" with reduced SSB transmission, as well as information according to the above embodiments, the detailed method of which follows the above embodiments.

[0326] In operation 1303, the UE performs an "SSB-free SCell" operation according to the base station configuration. According to the above embodiments, based on the reference cell and / or reference signal configured according to the above embodiments, the UE can determine the QCL associated with the "SSB-free SCell" by referring to the "reference signal" of the "reference cell," and / or perform at least one of measurement report generation and transmission, determination of uplink signal or channel transmission power, and configuration of downlink signal transmission power. Furthermore, the UE needs to meet the MRTD tolerances described in the above embodiments.

[0327] References can be omitted. Figure 13 The operations described may be altered in order, or undescribed operations may be added and the present disclosure performed. The flowcharts above illustrate exemplary methods that can be implemented according to the principles of the present disclosure, and various changes can be made to the methods shown in the flowcharts of this specification. For example, although illustrated as a series of operations, the various operations in each figure may overlap, may be operated in parallel, may be operated in a different order, or may be operated multiple times. In another example, operations may be omitted or replaced with other operations.

[0328] Figure 14 This is a schematic diagram illustrating an example of a base station process according to an embodiment of the present disclosure. Specifically, Figure 14The flowchart illustrates a process in which, when a base station reduces SSB transmissions of the SCell to lower energy consumption in a system using carrier aggregation, the base station notifies the UE of the corresponding configuration and performs related operations.

[0329] refer to Figure 14 In operation 1401, the base station may request the UE to send UE capability information. In operation 1402, the base station acquires UE capability information including the capability to support base station power-saving modes. Specifically, the UE capability information may include at least one capability information related to base station power-saving modes, such as information indicating whether the UE supports base station power-saving modes, information indicating whether the UE supports carrier aggregation, information indicating whether the UE supports base station SSB transmission reduction operations, control information related to the frequency bands supported by the UE, and control information related to the channel bandwidth supported by the UE.

[0330] Subsequently, in operation 1403, the base station notifies the UE of the "SCell without SSB" configuration. According to the above embodiment, the base station can notify the UE of the "SCell without SSB" configuration via the SSB configuration information or additional control information already described above. Furthermore, as mentioned above, the information associated with the "SCell without SSB" configuration can be included in the "RRC reconfiguration" message or the SCell activation command. Additionally, the information according to the above embodiment can also be included in the "SCell without SSB" configuration.

[0331] In operation 1404, the base station performs scheduling operations for the UE based on the "SCell without SSB" configuration. According to the above embodiment, the base station can determine the QCL associated with the "SCell without SSB" by referring to the "reference signal" of the "reference cell". Alternatively, the base station can receive measurement reports based on the configured reference cell and / or reference signal, receive uplink signals or channels transmitted using transmission power determined based on the configured reference cell and / or reference signal, or generate downlink transmission power parameters based on the reference cell and / or reference signal and send them to the UE. According to the above embodiment, the base station performs scheduling to satisfy the UE's MRTD tolerance.

[0332] You can also omit the reference. Figure 14 This disclosure is performed after the described steps, their order, or the addition of steps not described. The flowcharts above illustrate exemplary methods that can be implemented according to the principles of this disclosure, and various modifications can be made to the methods shown in the flowcharts herein. For example, although shown as a series of operations, the various operations in each figure may overlap, occur in parallel, occur in different orders, or occur multiple times. In another example, an operation may be omitted or replaced by another operation.

[0333] also, Figure 13 and 14 The methods described herein can be performed in combination with at least one of the first to fourth embodiments.

[0334] Within a cell controlled by a base station operating as described above, a UE that supports UE operation according to the base station power-saving mode (hereinafter referred to as UE A) and a UE that does not support UE operation according to the base station power-saving mode (hereinafter referred to as UE B) can coexist. UE A can perform UE operation according to the specific embodiments described above. UE B cannot respond to changes in the gNB transmission scheme according to the base station power-saving mode and is therefore concerned about performance degradation related to transmission efficiency, cell capacity, throughput, and UE power consumption. Therefore, if the base station can distinguish between UE A and UE B by referring to UE capability reports from the UE, additional actions can be taken to prevent performance degradation of UE B. For example, the base station can switch UE B to a neighboring cell with a base station in normal base station mode, instead of the current cell that should be switched to base station power-saving mode.

[0335] The fifth embodiment can be modified in various ways. For example, the step of the UE reporting its capabilities to the base station can be omitted.

[0336] Figure 15 An example of a UE transceiver device in a wireless communication system according to embodiments of the present disclosure is shown. For ease of description, devices not directly associated with the present disclosure may not be shown and described.

[0337] refer to Figure 15 The UE may include: a transmitter 1504, which includes an uplink transmission processing block 1501, a multiplexer 1502, and a transmission RF block 1503; a receiver 1508, which includes a downlink reception processing block 1505, a demultiplexer 1506, and a reception RF block 1507; and a controller 1509. As described above, the controller 1509 can control the various components of the receiver 1508 to receive data channels or control channels transmitted by the base station, and control the various components of the transmitter 1504 to transmit uplink signals.

[0338] The uplink transmission processing block 1501 in the UE's transmitter 1504 can generate the signal to be transmitted by performing processes such as channel coding and modulation. The signal generated by the uplink transmission processing block 1501 can be multiplexed with another uplink signal by the multiplexer 1502, processed by the transmit RF block 1503, and then transmitted to the base station.

[0339] The UE's receiver 1508 demultiplexes the signals received from the base station and distributes them to each downlink receive processing block. The downlink receive processing block 1505 can acquire control information or data transmitted by the base station by performing processes such as demodulation and channel decoding on the downlink signals from the base station. The UE's receiver 1508 can apply the output from the downlink receive processing blocks to the controller 1509, thereby supporting the operation of the controller 1509.

[0340] Figure 16 An example of the structure of a UE according to an embodiment of this disclosure is shown.

[0341] refer to Figure 16 The UE disclosed herein may include a processor 1630, a transceiver 1610, and a memory 1620. However, the components of the UE are not limited to the examples described above. For example, the UE may include more or fewer components than those described above. Furthermore, the processor 1630, transceiver 1610, and memory 1620 may be implemented as a single chip. According to one embodiment, Figure 16 The transceiver 1610 may include Figure 15 The transmitter 1504 and receiver 1508. Furthermore, Figure 16 The processor 1630 may include Figure 15 The controller is 1509.

[0342] According to embodiments, processor 1630 can control a series of processes that enable the UE to operate according to the embodiments of the present disclosure described above. For example, according to embodiments of the present disclosure, processor 1630 can control the components of the UE to perform UE transmission and reception methods according to the "SSB-free SCell" configuration of the base station. Processor 1630 may include one or more processors, and processor 1630 can execute programs stored in memory 1620 to perform UE transmission and reception operations in a wireless communication system employing the operations described above in the present disclosure.

[0343] Transceiver 1610 can transmit / receive signals with a base station. Signals transmitted / received by the base station may include control information and data. Transceiver 1610 may include an RF transmitter configured to up-convert and amplify the frequency of the transmitted signal, an RF receiver configured to amplify the received signal with low noise and down-convert its frequency, etc. However, this is merely one embodiment of transceiver 1610, and the components of transceiver 1610 are not limited to RF transmitters and RF receivers. Furthermore, transceiver 1610 can receive signals via a radio channel, output them to processor 1630, and transmit signals output from processor 1630 via a radio channel.

[0344] According to an embodiment, memory 1620 may store programs and data required for UE operation. Furthermore, memory 1620 may store control information or data included in signals transmitted / received by the UE. Memory 1620 may include storage media such as ROM, RAM, hard disk, CD-ROM, and DVD, or a combination of storage media. Memory 1620 may include one or more memories, and according to an embodiment, memory 1620 may store programs for performing UE transmission / reception operations according to a “SCell without SSB” configuration corresponding to the above embodiments of this disclosure.

[0345] Figure 17 An example of the structure of a base station according to an embodiment of this disclosure is shown.

[0346] refer to Figure 17 The base station disclosed herein may include a processor 1730, a transceiver 1710, and a memory 1720. However, the components of the base station are not limited to the examples described above. For example, the base station may include more or fewer components than those described above. Furthermore, the processor 1730, transceiver 1710, and memory 1720 may be implemented as a single chip.

[0347] Processor 1730 can control a series of processes that enable the base station to operate according to the embodiments of the present disclosure described above. For example, according to embodiments of the present disclosure, processor 1730 can control components of the base station to perform a method for scheduling a UE according to an "SSB-free SCell" configuration. Processor 1730 may include one or more processors, and processor 1730 can execute a program stored in memory 1720 to perform a method corresponding to the "SSB-free SCell" configuration of the UE of the present disclosure described above.

[0348] Transceiver 1710 can transmit / receive signals with the UE. The signals transmitted / received by the UE can include control information and data. Transceiver 1710 may include an RF transmitter configured to up-convert and amplify the frequency of the transmitted signal, an RF receiver configured to amplify the received signal with low noise and down-convert its frequency, etc. However, this is merely one embodiment of transceiver 1710, and the components of transceiver 1710 are not limited to RF transmitters and RF receivers. Furthermore, transceiver 1710 can receive signals via a radio channel, output them to processor 1730, and transmit signals output from processor 1730 via a radio channel.

[0349] According to an embodiment, memory 1720 may store programs and data required for base station operation. Furthermore, memory 1720 may store control information or data included in signals transmitted / received by the base station. Memory 1720 may include storage media such as ROM, RAM, hard disk, CD-ROM, and DVD, or a combination of storage media. Additionally, memory 1720 may include multiple memories. According to an embodiment, memory 1720 may store a program for performing a method for scheduling a UE according to a "SCell without SSB" configuration corresponding to an embodiment of this disclosure.

[0350] The methods disclosed in the claims and / or the methods of the embodiments described in this disclosure may be implemented by hardware, software, or a combination of hardware and software.

[0351] When these methods are implemented in software, a computer-readable storage medium may be provided for storing one or more programs (software modules). One or more programs stored in the computer-readable storage medium may be configured to be executed by one or more processors within an electronic device. The at least one program includes instructions that cause the electronic device to perform methods according to the various embodiments of this disclosure as defined by the appended claims and / or disclosed herein.

[0352] These programs (software modules or software) can be stored in non-volatile memory, including random access memory and flash memory, read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), disk storage devices, compact disc-ROM (CD-ROM), digital versatile disc (DVD) or other types of optical storage devices, or magnetic tape. Alternatively, any combination of some or all of them can form the memory storing the program. Furthermore, electronic devices may include multiple such memories.

[0353] Furthermore, the program can be stored on an attachable storage device that can be accessed by the electronic device via a communication network such as the Internet, intranet, local area network (LAN), wide area network (WLAN), and storage area network (SAN), or a combination thereof. Such a storage device can access the electronic device via an external port. Additionally, a standalone storage device on the communication network can access portable electronic devices.

[0354] In the detailed embodiments of this disclosure described above, elements included in this disclosure are represented in a singular or plural form according to the presented detailed embodiments. However, for the sake of convenience of description, singular or plural forms have been suitably chosen as presented, and this disclosure is not limited to elements expressed in a singular or plural form; therefore, an element expressed in a plural form may also include a single element, or an element expressed in a singular form may also include multiple elements.

[0355] The embodiments of this disclosure described and illustrated in the specification and drawings are merely specific examples presented to readily explain the technical content of the embodiments of this disclosure and to aid in understanding them, and are not intended to limit the scope of the embodiments of this disclosure. Although specific terminology is used, it is used only in a general sense to readily explain the technical content of this disclosure and to aid in understanding it, and is not intended to limit the scope of this disclosure. Furthermore, it will be apparent to those skilled in the art that other variations based on the technical ideas of this disclosure can be implemented. In addition, the various embodiments described above can be combined as needed. For example, a portion of one embodiment of this disclosure can be combined with a portion of another embodiment to operate a base station and a terminal. Furthermore, the embodiments of this disclosure can be applied to other communication systems, and other variations based on the technical ideas of the embodiments can also be implemented.

Claims

1. A method performed by a terminal in a communication system, the method comprising: Receive information about the reference cell from the base station; The first secondary cell (SCell) is identified as an SCell without an SSB; as well as Based on information about the reference cell, a second RS is identified that is in a quasi-co-located (QCL) relationship with the first reference signal (RS) of the first SCell. The second RS is the RS of the cell indicated by information about the reference cell.

2. The method according to claim 1, wherein, The second RS is the synchronization signal block (SSB).

3. The method according to claim 1, further comprising: Send terminal capability information supporting SCell without SSB to the base station.

4. The method according to claim 1, wherein, The maximum receive timing difference (MRTD) required for carrier aggregation (CA) of SCells without SSB is greater than or equal to the MRTD required for in-band CA, and less than the MRTD required for inter-band CA.

5. A method performed by a base station in a communication system, the method comprising: The first secondary cell (SCell) is identified as an SCell without an SSB; as well as Send information about the reference cell to the terminal. In this context, the first reference signal (RS) of the first SCell and the second RS are in a quasi-co-located (QCL) relationship, and the second RS is the RS of the cell indicated by information about the reference cell.

6. The method according to claim 5, wherein, The second RS is the synchronization signal block (SSB).

7. The method according to claim 5, further comprising: Receive terminal capability information from the terminal that supports SCells without SSB.

8. The method according to claim 5, wherein, The maximum receive timing difference (MRTD) required for carrier aggregation (CA) of SCells without SSB is greater than or equal to the MRTD required for in-band CA, and less than the MRTD required for inter-band CA.

9. A terminal in a communication system, the terminal comprising: transceiver; and The controller is configured to: Receive information about the reference cell from the base station. Identify whether the first secondary cell (SCell) is an SCell without an SSB, and Based on information about the reference cell, a second RS is identified that is in a quasi-co-located (QCL) relationship with the first reference signal (RS) of the first SCell. The second RS is the RS of the cell indicated by information about the reference cell.

10. The terminal according to claim 9, wherein, The second RS is the synchronization signal block (SSB).

11. The terminal according to claim 9, wherein, The controller is also configured to send terminal capability information supporting SSB-less SCells to the base station.

12. The terminal according to claim 9, wherein, The maximum receive timing difference (MRTD) required for carrier aggregation (CA) of SCells without SSB is greater than or equal to the MRTD required for in-band CA, and less than the MRTD required for inter-band CA.

13. A base station in a communication system, the base station comprising: transceiver; and The controller is configured to: Identify whether the first secondary cell (SCell) is an SCell without an SSB, and Send information about the reference cell to the terminal. In this context, the first reference signal (RS) of the first SCell and the second RS are in a quasi-co-located (QCL) relationship, and the second RS is the RS of the cell indicated by information about the reference cell.

14. The base station according to claim 13, wherein, The controller is also configured to receive terminal capability information from the terminal that supports SCells without SSB.

15. The base station according to claim 13, wherein, The maximum receive timing difference (MRTD) required for carrier aggregation (CA) of SCells without SSB is greater than or equal to the MRTD required for in-band CA, and less than the MRTD required for inter-band CA.

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