Method by user device, user device, processing device and storage medium, and method by base station and base station

Abstract

A UE may: receive a setting regarding a start bit position of a specific downlink control information format for a first information block associated with a first cell; request transmission of a first synchronization signal for the first cell; and receive the specific downlink control information format. The UE may determine whether transmission of the first synchronization signal is activated, on the basis of the first information block for the first cell in the specific downlink control information format.

Description

Method by user device, user device, processing device and storage medium, and method by base station and base station

[0001] This specification relates to wireless communication systems.

[0002] Various devices and technologies, such as machine-to-machine (M2M) communication, machine-type communication (MTC), and smartphones and tablet PCs (personal computers) that require high data transmission rates, are emerging and becoming widespread. Consequently, the amount of data required to be processed on cellular networks is rapidly increasing. To meet this rapidly increasing data processing demand, technologies such as carrier aggregation and cognitive radio are being developed to efficiently utilize more frequency bands, while multi-antenna technology and multi-BS cooperation technology are being developed to increase the data capacity transmitted within a limited frequency range.

[0003] As more and more communication devices demand greater capacity, the need for enhanced mobile broadband (eMBB) communications is emerging, surpassing legacy radio access technology (RAT). Furthermore, massive machine type communication (mMTC), which connects multiple devices and objects to provide diverse services anytime, anywhere, is a key issue to be considered in next-generation communications.

[0004] Additionally, discussions are underway on communication systems designed to accommodate reliability- and latency-sensitive services and user equipment (UE). The introduction of next-generation wireless access technologies is being discussed, including enhanced mobile broadband (eMBB), mMTC, and ultra-reliable and low latency communication (URLLC).

[0005] As the number of services / UEs that a network must support rapidly increases, the need for energy conservation in the network as well as power conservation in the UE is also gradually increasing.

[0006] One technical task of this specification is to provide methods and procedures for network energy conservation.

[0007] Another technical challenge of this specification is to provide methods and procedures for transmitting downlink signals to enable network energy conservation.

[0008] The technical tasks to be achieved by this specification are not limited to the technical tasks mentioned above, and other technical tasks not mentioned will be clearly understood by those skilled in the art related to this specification from the detailed description below.

[0009] In one aspect of this specification, a method by a user equipment (UE) is provided.

[0010] In another aspect of the present disclosure, a user equipment (UE) is provided. The UE comprises at least one processor; and at least one memory operably connected to the at least one processor and storing instructions that, when executed, cause the at least one processor to perform operations for the UE.

[0011] In another aspect of the present disclosure, a computer-readable, non-transitory storage medium is provided, wherein the storage medium stores at least one program code comprising instructions that, when executed, cause at least one processor to perform operations for a user equipment (UE).

[0012] The method by the UE, or the operations for the UE, may include: receiving a radio resource control (RRC) configuration, wherein the RRC configuration includes a configuration regarding a start bit position of a specific downlink control information format for a first information block associated with a first cell; transmitting a request for transmission of a first synchronization signal for the first cell; monitoring a downlink channel carrying the specific downlink control information format; obtaining, based on detection of the specific downlink control information format, the first information block for the first cell in the specific downlink control information format; determining, based on the first information block, whether the first synchronization signal is activated; and initiating monitoring of the first synchronization signal on the first cell based on the first synchronization signal being activated.

[0013] In another aspect of the present specification, a method by a base station (BS) is provided.

[0014] In another aspect of the present disclosure, a base station (BS) is provided. The BS includes at least one processor; and at least one memory operably connected to the at least one processor and storing instructions that, when executed, cause the at least one processor to perform operations for the BS.

[0015] The method by the BS, or the operations for the BS, may include: transmitting a radio resource control (RRC) configuration, wherein the RRC configuration includes a configuration regarding a start bit position of a specific downlink control information format for a first information block associated with a first cell; receiving a request for transmission of a first synchronization signal for the first cell; transmitting a downlink channel carrying the specific downlink control information format, wherein the first information block for the first cell in the specific downlink control information format includes information regarding whether the first synchronization signal is activated; and starting transmission of the first synchronization signal on the first cell based on the first synchronization signal being activated.

[0016] In each aspect of the present specification, the first information block may include bits indicating synchronization signal candidates for which transmission is to be activated among synchronization signal candidates for the first cell.

[0017] In each aspect of the present specification, the method by the UE, or the operations for the UE, may include: ceasing monitoring of the first synchronization signal based on receiving a deactivation indication for the first synchronization signal.

[0018] In each aspect of the present specification, the method by the BS, or the operations for the BS, may include: ceasing transmission of the first synchronization signal based on transmitting a deactivation indication for the first synchronization signal.

[0019] In each aspect of this specification, monitoring or transmitting of the first synchronization signal may be initiated at least after a predetermined applied delay after the specific downlink control information format is detected or transmitted.

[0020] In each aspect of the present specification, the method by the UE, or the operations for the UE, may include: receiving a plurality of sets of on-demand synchronization signal configurations for the first cell.

[0021] In each aspect of the present specification, the method by the BS, or the operations for the BS, may include: transmitting a plurality of sets of on-demand synchronization signal configurations for the first cell.

[0022] In each aspect of the present specification, each of the plurality of on-demand synchronization signal configuration sets may include at least one of: i) frequency resource information for on-demand synchronization signals, ii) time resource information for the on-demand synchronization signals, iii) candidate synchronization signal indices, iv) transmission windows for the on-demand synchronization signals, v) periods of the on-demand synchronization signals, vi) half-frame indices for the on-demand synchronization signals, or vii) transmission power related information for the on-demand synchronization signals.

[0023] In each aspect of the present specification, the method by the UE, or the operations for the UE, may include: receiving a cell discontinuous transmission (DTX) configuration for the first cell.

[0024] In each aspect of the present specification, the method by the BS, or the operations for the BS, may include: transmitting a cell discontinuous transmission (DTX) configuration for the first cell.

[0025] In each aspect of this specification, the cell DTX setting may include information regarding whether a synchronization signal transmission request for the first cell is allowed.

[0026] In each aspect of this specification, the monitoring or transmission of the first synchronization signal may be performed at different cycles in the active and non-active periods based on the cell DTX settings.

[0027] The above problem solving methods are only some of the examples of this specification, and various examples reflecting the technical features of this specification can be derived and understood by a person having ordinary knowledge in the relevant technical field based on the detailed description below.

[0028] According to some implementation(s) of this specification, methods and procedures for energy saving of a network, BS and / or UE may be provided.

[0029] According to some implementation(s) of this specification, methods and procedures for transmitting downlink signals to enable energy saving of a network, a BS and / or a UE may be provided.

[0030] The effects according to this specification are not limited to the effects mentioned above, and other effects not mentioned will be clearly understood by those skilled in the art related to this specification from the detailed description below.

[0031] To aid in understanding implementations of this specification, the accompanying drawings, which are included as part of the detailed description, provide examples of implementations of this specification and, together with the detailed description, illustrate implementations of this specification:

[0032] Figure 1 illustrates an example of a communication system 1 to which implementations of the present specification are applied;

[0033] FIG. 2 is a block diagram illustrating examples of communication devices capable of performing a method according to the present specification;

[0034] FIG. 3 illustrates another example of a wireless device capable of performing implementation(s) of the present specification;

[0035] FIG. 4 illustrates an example of a frame structure available in a 3rd generation partnership project (3GPP) based wireless communication system;

[0036] Figure 5 illustrates a resource grid of slots;

[0037] FIG. 6 illustrates physical channels used in a 3rd generation partnership project (3GPP)-based communication system, which is an example of a wireless communication system, and a signal transmission / reception process using the channels;

[0038] Figure 7 illustrates synchronization signal (SS) / physical broadcast channel (PBCH) blocks (SSBs) on a cell.

[0039] Figure 8 is a diagram illustrating the bitmaps used to indicate which SSBs are actually transmitted;

[0040] Figure 9 illustrates a process for acquiring system information (SI);

[0041] Figure 10 illustrates a random access process that may be applied to implementation(s) of this specification;

[0042] FIG. 11 illustrates an example of PDSCH time domain resource allocation by PDCCH and an example of PUSCH time domain resource allocation by PDCCH;

[0043] Figure 12 illustrates discontinuous reception (DRX) operation;

[0044] Figure 13 illustrates a case where a Long DRX cycle and a Short DRX cycle are set;

[0045] Figure 14 illustrates an example of SSB transmission by a BS operating multiple frequency bands;

[0046] FIG. 15 illustrates the flow of DL signal reception in a UE according to some implementations of the present specification;

[0047] Figure 16 illustrates the flow of DL signal transmission in BS according to some implementations of the present specification.

[0048] Hereinafter, implementations according to this specification will be described in detail with reference to the attached drawings. The detailed description provided below, together with the attached drawings, is intended to describe exemplary implementations of this specification and is not intended to represent the only possible implementations of this specification. The detailed description below includes specific details to provide a thorough understanding of this specification. However, one of ordinary skill in the art will appreciate that this specification may be practiced without these specific details.

[0049] In some cases, to avoid ambiguity in the concepts of this specification, known structures and devices may be omitted or illustrated in block diagram form focusing on the core functions of each structure and device. Furthermore, identical components are described using the same drawing reference numerals throughout this specification.

[0050] The techniques, devices, and systems described below can be applied to various wireless multiple access systems. Examples of multiple access systems include code division multiple access (CDMA) systems, frequency division multiple access (FDMA) systems, time division multiple access (TDMA) systems, orthogonal frequency division multiple access (OFDMA) systems, single carrier frequency division multiple access (SC-FDMA) systems, and multi-carrier frequency division multiple access (MC-FDMA) systems. CDMA can be implemented in wireless technologies such as Universal Terrestrial Radio Access (UTRA) or CDMA2000. TDMA can be implemented in wireless technologies such as Global System for Mobile communication (GSM), General Packet Radio Service (GPRS), and Enhanced Data Rates for GSM Evolution (EDGE) (i.e., GERAN). OFDMA can be implemented in wireless technologies such as IEEE (Institute of Electrical and Electronics Engineers) 802.11 (WiFi), IEEE 802.16 (WiMAX), IEEE 802-20, and E-UTRA (evolved-UTRA). UTRA is part of UMTS (Universal Mobile Telecommunication System), and 3GPP (3rd Generation Partnership Project) LTE (Long Term Evolution) is a part of E-UMTS that uses E-UTRA.3GPP LTE adopts OFDMA for the downlink (DL) and SC-FDMA for the uplink (UL). LTE-A (LTE-advanced) is an evolved form of 3GPP LTE.

[0051] For convenience of explanation, the following description assumes that this specification applies to 3GPP-based communication systems, such as LTE and NR. However, the technical features of this specification are not limited to this. For example, although the detailed description below is based on a mobile communication system corresponding to a 3GPP LTE / NR system, it can also be applied to any other mobile communication system, except for features specific to 3GPP LTE / NR.

[0052] For terms and technologies used in this specification that are not specifically explained, reference may be made to 3GPP-based standard documents, such as 3GPP TS 36.211, 3GPP TS 36.212, 3GPP TS 36.213, 3GPP TS 36.321, 3GPP TS 36.300 and 3GPP TS 36.331, 3GPP TS 37.213, 3GPP TS 38.211, 3GPP TS 38.212, 3GPP TS 38.213, 3GPP TS 38.214, 3GPP TS 38.300, 3GPP TS 38.304, 3GPP TS 38.331, etc.

[0053] In the examples of this specification described below, the expression "assumes" that a device "assumes" that the entity transmitting the channel transmits the channel in a manner consistent with the "assume." The entity receiving the channel may mean that, under the assumption that the channel was transmitted in a manner consistent with the "assume," the entity receiving the channel receives or decodes the channel in a manner consistent with the "assume."

[0054] In this specification, ' / ' may mean 'and / or'. For example, cell DTX / DRX may mean cell DTX and / or cell DRX.

[0055] In this specification, UE may be fixed or mobile, and includes various devices that communicate with a BS (base station) to transmit and / or receive user data and / or various control information. UE may be called (Terminal Equipment), MS (Mobile Station), MT (Mobile Terminal), UT (User Terminal), SS (Subscribe Station), wireless device, PDA (Personal Digital Assistant), wireless modem, handheld device, etc. In addition, in this specification, BS generally refers to a fixed station that communicates with UE and / or other BS, and exchanges various data and control information with UE and other BS. BS may be called by other terms such as ABS (Advanced Base Station), NB (Node-B), eNB (evolved-NodeB), BTS (Base Transceiver System), Access Point, PS (Processing Server), etc. In particular, the BS in UTRAN is called a Node-B, the BS in E-UTRAN is called an eNB, and the BS in a new radio access technology network is called a gNB. For convenience of explanation, BSs are collectively referred to as BSs below, regardless of the type or version of communication technology.

[0056] In this specification, a node refers to a fixed point that can transmit / receive radio signals by communicating with a UE. Various types of BSs can be used as nodes regardless of their names. For example, BSs, NBs, eNBs, pico-cell eNBs (PeNBs), home eNBs (HeNBs), relays, and repeaters can be nodes. Furthermore, a node may not be a BS. For example, it can be a radio remote head (RRH) or a radio remote unit (RRU). RRHs, RRUs, etc. generally have a lower power level than the BS. Since an RRH or RRU (hereinafter referred to as RRH / RRU) is generally connected to a BS via a dedicated line such as an optical cable, cooperative communication between an RRH / RRU and a BS can be performed more smoothly than cooperative communication between BSs that are generally connected via a wireless line. Each node is equipped with at least one antenna. The antenna may be a physical antenna, an antenna port, a virtual antenna, or an antenna group. A node is also called a point.

[0057] In this specification, a cell refers to a certain geographical area where one or more nodes provide communication services. Therefore, in this specification, communicating with a specific cell may mean communicating with a BS or node that provides communication services to the specific cell. In addition, the downlink / uplink signal of a specific cell refers to a downlink / uplink signal from / to a BS or node that provides communication services to the specific cell. A cell that provides uplink / downlink communication services to a UE is specifically referred to as a serving cell. In addition, the channel state / quality of a specific cell refers to the channel state / quality of a channel or communication link formed between a BS or node that provides communication services to the specific cell and the UE. In a 3GPP-based communication system, a UE can measure a downlink channel state from a specific node using CRS (Cell-specific Reference Signal) resources transmitted by antenna port(s) of the specific node on CRS resources allocated to the specific node and / or CSI-RS (Channel State Information Reference Signal) resources transmitted.

[0058] Meanwhile, 3GPP-based communication systems use the concept of cells to manage radio resources, and cells associated with radio resources are distinguished from cells in geographical areas.

[0059] A "cell" in a geographical area can be understood as the coverage over which a node can provide a service using a carrier, and a "cell" in a radio resource is associated with a bandwidth (BW), which is a frequency range configured by the carrier. Since downlink coverage, which is the range over which a node can transmit a valid signal, and uplink coverage, which is the range over which a node can receive a valid signal from a UE, depend on the carrier carrying the signal, the coverage of a node is also associated with the coverage of the "cell" of the radio resource used by the node. Therefore, the term "cell" can sometimes be used to mean the coverage of a service provided by a node, sometimes a radio resource, and sometimes the range over which a signal using the radio resource can reach with a valid intensity.

[0060] Meanwhile, the 3GPP communication standard uses the concept of a cell to manage radio resources. A "cell" associated with radio resources is defined as a combination of downlink resources (DL resources) and uplink resources (UL resources), i.e., a combination of a DL component carrier (CC) and an UL CC. A cell can be configured with DL resources alone or a combination of DL resources and UL resources. If carrier aggregation is supported, the linkage between the carrier frequency of the DL resources (or DL ​​CC) and the carrier frequency of the UL resources (or UL CC) can be indicated by system information. For example, the combination of DL resources and UL resources can be indicated by a System Information Block Type 2 (SIB2) linkage. Here, the carrier frequency can be the same as or different from the center frequency of each cell or CC. When carrier aggregation (CA) is established, the UE has only one radio resource control (RRC) connection with the network. One serving cell provides non-access stratum (NAS) mobility information during RRC connection establishment / re-establishment / handover, and one serving cell provides security input during RRC connection re-establishment / handover. Such a cell is called a primary cell (Pcell). A Pcell is a cell operating on the primary frequency where the UE performs initial connection establishment procedures or initiates connection re-establishment procedures.Depending on the UE capability, secondary cells (Scells) can be configured to form a set of serving cells together with Pcells. An Scell ​​can be configured after an RRC (Radio Resource Control) connection establishment has been made, and is a cell that provides additional radio resources in addition to the resources of a special cell (SpCell). The carrier corresponding to a Pcell in downlink is called a downlink primary CC (DL PCC), and the carrier corresponding to a Pcell in uplink is called an UL primary CC (UL PCC). The carrier corresponding to an Scell ​​in downlink is called a DL secondary CC (DL SCC), and the carrier corresponding to the Scell ​​in uplink is called an UL secondary CC (UL SCC).

[0061] For a UE for which CA is set and DC is not set, a Pcell PUCCH group (also referred to as a primary PUCCH group) consisting of a Pcell and zero or more Scells and a Scell ​​PUCCH group (also referred to as a secondary PUCCH group) consisting of only Scell(s) may be set. In the case of an Scell, an Scell ​​(hereinafter referred to as a PUCCH Scell) on which a PUCCH associated with the cell is transmitted may be set. An Scell ​​for which a PUCCH Scell ​​is indicated belongs to an Scell ​​PUCCH group (i.e., a secondary PUCCH group), and PUCCH transmission of the relevant UCI is performed on the PUCCH Scell, and an Scell ​​for which a PUCCH Scell ​​is not indicated or which is a Pcell and is indicated as a cell for PUCCH transmission belongs to a Pcell PUCCH group (i.e., a primary PUCCH group), and PUCCH transmission of the relevant UCI is performed on the Pcell. Hereinafter, if a UE is configured with an SCG and some implementations of this specification related to PUCCH are applied to the SCG, the primary cell may refer to a PSCell of the SCG. If a UE is configured with a PUCCH Scell ​​and some implementations of this specification related to PUCCH are applied to a secondary PUCCH group, the primary cell may refer to a PUCCH Scell ​​of the secondary PUCCH group.

[0062] In a wireless communication system, a UE receives information from a base station (BS) via the downlink (DL), and the UE transmits information to the base station via the uplink (UL). The information transmitted and / or received by the BS and UE includes data and various control information, and various physical channels exist depending on the type and purpose of the information they transmit and / or receive.

[0063] 3GPP-based communication standards define downlink physical channels corresponding to resource elements that carry information originating from higher layers, and downlink physical signals corresponding to resource elements that are used by the physical layer but do not carry information originating from higher layers. For example, the physical downlink shared channel (PDSCH), physical broadcast channel (PBCH), and physical downlink control channel (PDCCH) are defined as downlink physical channels, and reference signals and synchronization signals are defined as downlink physical signals. A reference signal (RS), also referred to as a pilot, refers to a signal with a predefined special waveform that is known to the BS and the UE. For example, the demodulation reference signal (DMRS), the channel state information RS (CSI-RS), and the positioning reference signal (PRS) are defined as downlink reference signals. 3GPP-based communication standards define uplink physical channels corresponding to resource elements that carry information originating from higher layers, and uplink physical signals corresponding to resource elements that are used by the physical layer but do not carry information originating from higher layers.For example, a physical uplink shared channel (PUSCH), a physical uplink control channel (PUCCH), and a physical random access channel (PRACH) are defined as uplink physical channels, and a demodulation reference signal (DMRS) for uplink control / data signals and a sounding reference signal (SRS) used for uplink channel measurement are defined.

[0064] In this specification, PDCCH (Physical Downlink Control CHannel) refers to a set of time-frequency resources (e.g., resource elements (REs)) that carry DCI (Downlink Control Information), and PDSCH (Physical Downlink Shared CHannel) refers to a set of time-frequency resources that carry downlink data. In addition, PUCCH (Physical Uplink Control CHannel), PUSCH (Physical Uplink Shared CHannel), and PRACH (Physical Random Access CHannel) refer to sets of time-frequency resources that carry UCI (Uplink Control Information), uplink data, and random access signals, respectively (respectively). Hereinafter, the expression that a user equipment transmits / receives a PUCCH / PUSCH / PRACH is used with the same meaning as that uplink control information / uplink data / random access signals are transmitted / received on or through the PUCCH / PUSCH / PRACH, respectively. Additionally, the expression that BS transmits / receives PBCH / PDCCH / PDSCH is used with the same meaning as transmitting broadcast information / downlink control information / downlink data on or through PBCH / PDCCH / PDSCH, respectively.

[0065] In this specification, radio resources (e.g., time-frequency resources) scheduled or configured by the BS to the UE for transmission or reception of PUCCH / PUSCH / PDSCH are also referred to as PUCCH / PUSCH / PDSCH resources.

[0066] Since the communication device receives a synchronization signal (SS), DMRS, CSI-RS, PRS, PBCH, PDCCH, PDSCH, PUSCH, and / or PUCCH in the form of radio signals on a cell, it cannot selectively receive through an RF receiver only radio signals including only a specific physical channel or only a specific physical signal, or selectively receive through an RF receiver only radio signals excluding only a specific physical channel or only a physical signal. In actual operation, the communication device first receives radio signals on a cell through an RF receiver, converts the radio signals, which are RF band signals, into baseband signals, and decodes a physical signal and / or a physical channel within the baseband signals using one or more processors. Thus, in some implementations of the present specification, not receiving a physical signal and / or a physical channel may not actually mean that the communication device does not receive wireless signals containing the physical signal and / or physical channel at all, but rather that it does not attempt to recover the physical signal and / or physical channel from the wireless signals, e.g., does not attempt to decode the physical signal and / or the physical channel.

[0067] As more and more communication devices demand greater communication capacity, the need for improved mobile broadband communication over existing radio access technology (RAT) is emerging. Furthermore, massive MTC, which connects numerous devices and objects to provide diverse services anytime, anywhere, is also a key issue to be considered in next-generation communications. Furthermore, communication system design that considers reliability and latency-sensitive services / UEs is being discussed. The introduction of next-generation RATs that take advanced mobile broadband communication, massive MTC, and URLLC (Ultra-Reliable and Low Latency Communication) into account is currently under discussion. 3GPP is currently conducting studies on next-generation mobile communication systems beyond EPC. For convenience, this technology is referred to as new RAT (NR) or 5G RAT, and a system that uses or supports NR is referred to as an NR system.

[0068] FIG. 1 illustrates an example of a communication system 1 to which implementations of the present specification are applied. Referring to FIG. 1, the communication system (1) applied to the present specification includes a wireless device, a BS, and a network. Here, the wireless device refers to a device that performs communication using a wireless access technology (e.g., 5G NR (New RAT), LTE (e.g., E-UTRA)) and may be referred to as a communication / wireless / 5G device. Although not limited thereto, the wireless device may include a robot (100a), a vehicle (100b-1, 100b-2), an XR (eXtended Reality) device (100c), a hand-held device (100d), a home appliance (100e), an IoT (Internet of Things) device (100f), and an AI device / server (400). For example, the vehicle may include a vehicle equipped with a wireless communication function, an autonomous vehicle, a vehicle capable of performing vehicle-to-vehicle communication, etc. Here, the vehicle may include an Unmanned Aerial Vehicle (UAV) (e.g., a drone). XR devices include AR (Augmented Reality) / VR (Virtual Reality) / MR (Mixed Reality) devices, and may be implemented in the form of a Head-Mounted Device (HMD), a Head-Up Display (HUD) installed in a vehicle, a television, a smartphone, a computer, a wearable device, a home appliance, digital signage, a vehicle, a robot, etc. Mobile devices may include a smartphone, a smart pad, a wearable device (e.g., a smart watch, smart glasses), a computer (e.g., a laptop, etc.), etc. Home appliances may include a TV, a refrigerator, a washing machine, etc. IoT devices may include sensors, smart meters, etc. For example, a BS or network may also be implemented as a wireless device, and a specific wireless device may act as a BS / network node to other wireless devices.

[0069] Wireless devices (100a to 100f) can be connected to a network (300) via a BS (200). Artificial Intelligence (AI) technology can be applied to the wireless devices (100a to 100f), and the wireless devices (100a to 100f) can be connected to an AI server (400) via a network (300). The network (300) can be configured using a 3G network, a 4G (e.g., LTE) network, a 5G (e.g., NR) network, etc. The wireless devices (100a to 100f) can communicate with each other via the BS (200) / network (300), but can also communicate directly (e.g., sidelink communication) without going through the BS / network. For example, vehicles (100b-1, 100b-2) can communicate directly (e.g., V2V (Vehicle to Vehicle) / V2X (Vehicle to Everything) communication). In addition, IoT devices (e.g., sensors) can communicate directly with other IoT devices (e.g., sensors) or other wireless devices (100a to 100f).

[0070] Wireless communication / connection (150a, 150b) can be performed between wireless devices (100a~100f) / BS (200) - BS (200) / wireless devices (100a~100f). Here, the wireless communication / connection can be performed through various wireless access technologies (e.g., 5G NR) for uplink / downlink communication (150a) and sidelink communication (150b) (or D2D communication). Through the wireless communication / connection (150a, 150b), the wireless device and the BS / wireless device can transmit / receive wireless signals to / from each other. To this end, at least some of various configuration information setting processes for transmitting / receiving wireless signals, various signal processing processes (e.g., channel encoding / decoding, modulation / demodulation, resource mapping / demapping, etc.), and resource allocation processes can be performed based on various proposals of this specification.

[0071] FIG. 2 is a block diagram illustrating examples of communication devices capable of performing a method according to the present specification. Referring to FIG. 2, a first wireless device (100) and a second wireless device (200) can transmit and / or receive wireless signals via various wireless access technologies (e.g., LTE, NR). Here, {the first wireless device (100), the second wireless device (200)} can correspond to {the wireless device (100x), the BS (200)} and / or {the wireless device (100x), the wireless device (100x)} of FIG. 1.

[0072] A first wireless device (100) includes one or more processors (102) and one or more memories (104), and may further include one or more transceivers (106) and / or one or more antennas (108). The processor (102) controls the memories (104) and / or the transceivers (106), and may be configured to implement functions, procedures, and / or methods described / suggested below. For example, the processor (102) may process information in the memory (104) to generate first information / signals, and then transmit a wireless signal including the first information / signals via the transceivers (106). In addition, the processor (102) may receive a wireless signal including second information / signals via the transceivers (106), and then store information obtained from signal processing of the second information / signals in the memory (104). The memory (104) may be connected to the processor (102) and may store various information related to the operation of the processor (102). For example, the memory (104) may perform some or all of the processes controlled by the processor (102), or may store software code including commands for performing the procedures and / or methods described / proposed below. Here, the processor (102) and the memory (104) may be part of a communication modem / circuit / chip designed to implement wireless communication technology (e.g., LTE, NR). The transceiver (106) may be connected to the processor (102) and may transmit and / or receive wireless signals via one or more antennas (108). The transceiver (106) may include a transmitter and / or a receiver. The transceiver (106) may be used interchangeably with an RF (Radio Frequency) unit. In this specification, a wireless device may also mean a communication modem / circuit / chip.

[0073] The second wireless device (200) includes one or more processors (202), one or more memories (204), and may further include one or more transceivers (206) and / or one or more antennas (208). The processor (202) controls the memories (204) and / or the transceivers (206), and may be configured to implement the functions, procedures, and / or methods described / suggested below. For example, the processor (202) may process information in the memory (204) to generate third information / signals, and then transmit a wireless signal including the third information / signals via the transceivers (206). In addition, the processor (202) may receive a wireless signal including fourth information / signals via the transceivers (206), and then store information obtained from signal processing of the fourth information / signals in the memory (204). The memory (204) may be connected to the processor (202) and may store various information related to the operation of the processor (202). For example, the memory (204) may perform some or all of the processes controlled by the processor (202), or may store software code including commands for performing the procedures and / or methods described / proposed below. Here, the processor (202) and the memory (204) may be part of a communication modem / circuit / chip designed to implement wireless communication technology (e.g., LTE, NR). The transceiver (206) may be connected to the processor (202) and may transmit and / or receive wireless signals via one or more antennas (208). The transceiver (206) may include a transmitter and / or a receiver. The transceiver (206) may be used interchangeably with an RF unit. In this specification, a wireless device may also mean a communication modem / circuit / chip.

[0074] The wireless communication technology implemented in the wireless device (100, 200) of the present specification may include not only LTE, NR, and 6G, but also Narrowband Internet of Things for low-power communication. At this time, for example, NB-IoT technology may be an example of LPWAN (Low Power Wide Area Network) technology, and may be implemented with standards such as LTE Cat NB1 and / or LTE Cat NB2, and is not limited to the above-described names. Additionally or alternatively, the wireless communication technology implemented in the wireless device (XXX, YYY) of the present specification may perform communication based on LTE-M technology. At this time, for example, LTE-M technology may be an example of LPWAN technology, and may be called by various names such as eMTC (enhanced Machine Type Communication). For example, LTE-M technology can be implemented by at least one of various standards such as 1) LTE CAT 0, 2) LTE Cat M1, 3) LTE Cat M2, 4) LTE non-BL (non-Bandwidth Limited), 5) LTE-MTC, 6) LTE Machine Type Communication, and / or 7) LTE M, and is not limited to the above-described names. Additionally or alternatively, the wireless communication technology implemented in the wireless device (XXX, YYY) of the present specification can include at least one of ZigBee, Bluetooth, and Low Power Wide Area Network (LPWAN) considering low-power communication, and is not limited to the above-described names. For example, ZigBee technology can create personal area networks (PAN) related to small / low-power digital communication based on various standards such as IEEE 802.15.4, and can be called by various names.

[0075] Hereinafter, hardware elements of the wireless device (100, 200) will be described in more detail. Although not limited thereto, one or more protocol layers may be implemented by one or more processors (102, 202). For example, one or more processors (102, 202) may implement one or more layers (e.g., functional layers such as a physical (PHY) layer, a medium access control (MAC) layer, a radio link control (RLC) layer, a packet data convergence protocol (PDCP) layer, a radio resource control (RRC) layer, and a service data adaptation protocol (SDAP) layer). One or more processors (102, 202) may generate one or more protocol data units (PDUs) and / or one or more service data units (SDUs) according to the functions, procedures, proposals, and / or methods disclosed in this document. One or more processors (102, 202) may generate messages, control information, data or information according to the functions, procedures, proposals and / or methods disclosed herein. One or more processors (102, 202) may generate signals (e.g., baseband signals) including PDUs, SDUs, messages, control information, data or information according to the functions, procedures, proposals and / or methods disclosed herein and provide the signals to one or more transceivers (106, 206). One or more processors (102, 202) may receive signals (e.g., baseband signals) from one or more transceivers (106, 206) and obtain PDUs, SDUs, messages, control information, data or information according to the functions, procedures, proposals and / or methods disclosed herein.

[0076] One or more processors (102, 202) may be referred to as a controller, a microcontroller, a microprocessor, or a microcomputer. One or more processors (102, 202) may be implemented by hardware, firmware, software, or a combination thereof. For example, one or more Application Specific Integrated Circuits (ASICs), one or more Digital Signal Processors (DSPs), one or more Digital Signal Processing Devices (DSPDs), one or more Programmable Logic Devices (PLDs), or one or more Field Programmable Gate Arrays (FPGAs) may be included in one or more processors (102, 202). The functions, procedures, proposals, and / or methods disclosed in this document may be implemented using firmware or software, and the firmware or software may be implemented to include modules, procedures, functions, etc. Firmware or software configured to perform the functions, procedures, suggestions and / or methods disclosed in this document may be included in one or more processors (102, 202) or stored in one or more memories (104, 204) and executed by one or more processors (102, 202). The functions, procedures, suggestions and / or methods disclosed in this document may be implemented using firmware or software in the form of codes, instructions and / or sets of instructions.

[0077] One or more memories (104, 204) may be coupled to one or more processors (102, 202) and may store various forms of data, signals, messages, information, programs, codes, instructions, and / or commands. The one or more memories (104, 204) may be configured as ROM, RAM, EPROM, flash memory, hard drives, registers, cache memory, computer-readable storage media, and / or combinations thereof. The one or more memories (104, 204) may be located internally and / or externally to the one or more processors (102, 202). Additionally, the one or more memories (104, 204) may be coupled to the one or more processors (102, 202) via various technologies, such as wired or wireless connections.

[0078] One or more transceivers (106, 206) can transmit user data, control information, wireless signals / channels, etc., as mentioned in the methods and / or flowcharts of this document, to one or more other devices. One or more transceivers (106, 206) can receive user data, control information, wireless signals / channels, etc., as mentioned in the functions, procedures, proposals, methods and / or flowcharts of this document, from one or more other devices. For example, one or more transceivers (106, 206) can be coupled to one or more processors (102, 202) and can transmit and / or receive wireless signals. For example, one or more processors (102, 202) can control one or more transceivers (106, 206) to transmit user data, control information, or wireless signals to one or more other devices. Additionally, one or more processors (102, 202) may control one or more transceivers (106, 206) to receive user data, control information, or wireless signals from one or more other devices. Additionally, one or more transceivers (106, 206) may be coupled to one or more antennas (108, 208), and one or more transceivers (106, 206) may be configured to transmit and / or receive user data, control information, wireless signals / channels, or the like, as referred to in the functions, procedures, proposals, methods, and / or operational flowcharts disclosed in this document, via one or more antennas (108, 208). In this document, one or more antennas may be multiple physical antennas or multiple logical antennas (e.g., antenna ports). One or more transceivers (106, 206) may convert received user data, control information, wireless signals / channels, etc. from RF band signals to baseband signals for processing using one or more processors (102, 202).One or more transceivers (106, 206) may convert user data, control information, wireless signals / channels, etc. processed by one or more processors (102, 202) from baseband signals to RF band signals. For this purpose, one or more transceivers (106, 206) may include an (analog) oscillator and / or filter.

[0079] FIG. 3 illustrates another example of a wireless device capable of performing implementation(s) of the present specification. Referring to FIG. 3, the wireless device (100, 200) corresponds to the wireless device (100, 200) of FIG. 2 and may be composed of various elements, components, units / units, and / or modules. For example, the wireless device (100, 200) may include a communication unit (110), a control unit (120), a memory unit (130), and additional elements (140). The communication unit may include a communication circuit (112) and a transceiver(s) (114). For example, the communication circuit (112) may include one or more processors (102, 202) and / or one or more memories (104, 204) of FIG. 2. For example, the transceiver(s) (114) may include one or more transceivers (106, 206) and / or one or more antennas (108, 208) of FIG. 2. The control unit (120) is electrically connected to the communication unit (110), the memory unit (130), and the additional elements (140) and controls the overall operation of the wireless device. For example, the control unit (120) may control the electrical / mechanical operation of the wireless device based on the program / code / command / information stored in the memory unit (130). In addition, the control unit (120) may transmit information stored in the memory unit (130) to an external device (e.g., another communication device) via a wireless / wired interface through the communication unit (110), or store information received from an external device (e.g., another communication device) via a wireless / wired interface in the memory unit (130).

[0080] The additional element (140) may be configured in various ways depending on the type of the wireless device. For example, the additional element (140) may include at least one of a power unit / battery, an input / output (I / O) unit, a driving unit, and a computing unit. Although not limited thereto, the wireless device may be implemented in the form of a robot (Fig. 1, 100a), a vehicle (Fig. 1, 100b-1, 100b-2), an XR device (Fig. 1, 100c), a portable device (Fig. 1, 100d), a home appliance (Fig. 1, 100e), an IoT device (Fig. 1, 100f), a UE for digital broadcasting, a hologram device, a public safety device, an MTC device, a medical device, a fintech device (or a financial device), a security device, a climate / environmental device, an AI server / device (Fig. 1, 400), a BS (Fig. 1, 200), a network node, etc. Wireless devices may be mobile or stationary depending on the use / service.

[0081] In FIG. 3, various elements, components, units / parts, and / or modules within the wireless device (100, 200) may be entirely interconnected via a wired interface, or at least some may be wirelessly connected via a communication unit (110). For example, within the wireless device (100, 200), the control unit (120) and the communication unit (110) may be wired, and the control unit (120) and a first unit (e.g., 130, 140) may be wirelessly connected via the communication unit (110). In addition, each element, component, unit / part, and / or module within the wireless device (100, 200) may further include one or more elements. For example, the control unit (120) may be composed of one or more processor sets. For example, the control unit (120) may be composed of a set of a communication control processor, an application processor, an electronic control unit (ECU), a graphics processing processor, a memory control processor, etc. As another example, the memory unit (130) may be composed of RAM (Random Access Memory), DRAM (Dynamic RAM), ROM (Read Only Memory), flash memory, volatile memory, non-volatile memory, and / or a combination thereof.

[0082] In this specification, at least one memory (e.g., 104 or 204) can store instructions or programs that, when executed, cause at least one processor operably connected to the at least one memory to perform operations according to some embodiments or implementations of the present specification.

[0083] In this specification, a computer-readable (non-volatile) storage medium can store at least one instruction or computer program, which when executed by at least one processor causes the at least one processor to perform operations according to some embodiments or implementations of this specification.

[0084] In this specification, a processing device or apparatus may include at least one processor and at least one computer memory operatively connected to the at least one processor. The at least one computer memory may store instructions or programs, which, when executed, cause at least one processor operatively connected to the at least one memory to perform operations according to some embodiments or implementations of the present specification.

[0085] In this specification, a computer program may be stored in at least one computer-readable (non-volatile) storage medium and may include program code that, when executed, performs operations according to some implementations of the present specification or causes at least one processor to perform operations according to some implementations of the present specification. The computer program may be provided in the form of a computer program product. The computer program product may include at least one computer-readable (non-volatile) storage medium.

[0086] A communications device of the present specification comprises at least one processor; and at least one computer memory operably connected to said at least one processor and storing instructions that, when executed, cause said at least one processor to perform operations according to the example(s) of the present specification described below.

[0087] Figure 4 illustrates an example of a frame structure available in a 3GPP-based wireless communication system.

[0088] The structure of the frame in Fig. 4 is merely an example, and the number of subframes, the number of slots, and the number of symbols in the frame can be varied. In an NR system, OFDM numerology (e.g., subcarrier spacing (SCS)) may be set differently between multiple cells aggregated to a single UE. Accordingly, the (absolute time) duration of a time resource (e.g., a subframe, a slot, or a transmission time interval (TTI)) consisting of the same number of symbols may be set differently between the aggregated cells. Here, the symbol may include an OFDM symbol (or a cyclic prefix - orthogonal frequency division multiplexing (CP-OFDM) symbol), an SC-FDMA symbol (or a discrete Fourier transform-spread-OFDM (DFT-s-OFDM) symbol). In this specification, the terms symbol, OFDM-based symbol, OFDM symbol, CP-OFDM symbol, and DFT-s-OFDM symbols are interchangeable.

[0089] Referring to Figure 4, in the NR system, uplink and downlink transmissions are organized into frames. Each frame is T f = (△f max *N f / 100)*T c = 10 ms duration, divided into two half-frames of 5 ms each. Here, T is the basic time unit for NR. c = 1 / (△fmax *N f ) and △f max = 480*10 3 Hz, and N f =4096. For reference, T is the basic time unit for LTE. s = 1 / (△f ref *N f,ref ) and △f ref = 15*10 3 Hz, and N f,ref =2048. T s Wow T c is a constant κ = T s / T c = 64 relationship. Each half-frame consists of 5 subframes, and the duration of a single subframe is T. sf is 1ms. Subframes are further divided into slots, and the number of slots in a subframe depends on the subcarrier spacing. Each slot consists of 14 or 12 OFDM symbols based on the cyclic prefix. For a normal cyclic prefix (CP), each slot consists of 14 OFDM symbols, and for an extended CP, each slot consists of 12 OFDM symbols. The numerology is exponentially scalable with a subcarrier spacing △f = 2. u *Depends on 15 kHz. The following table shows the subcarrier spacing for regular CP △f = 2. u *Number of OFDM symbols per slot at 15 kHz (N) slot symb ), number of slots per frame (N frame,u slot ) and the number of slots per subframe (N subframe,u slot ) is shown.

[0090]

[0091] The following table shows the subcarrier spacing for extended CP △f = 2. u*Indicates the number of OFDM symbols per slot, the number of slots per frame, and the number of slots per subframe at 15 kHz.

[0092]

[0093] For a subcarrier spacing setting u, slots are n in increasing order within a subframe. u s ∈ {0, ..., nsubframe,u slot - 1} and n in increasing order within the frame u s,f ∈ {0, ..., n frame,u slot - Numbered as 1}.

[0094] Figure 5 illustrates the resource grid of a slot. A slot contains multiple symbols (e.g., 14 or 12) in the time domain. For each numeral (e.g., subcarrier spacing) and carrier, a common resource block (CRB) N is indicated by higher layer signaling (e.g., radio resource control (RRC) signaling). start,u grid Starting from,N size,u grid,x *N RB sc Dog subcarriers and N subframe,u symb A resource grid of OFDM symbols is defined, where N size,u grid,x is the number of resource blocks (RBs) in the resource grid, and the subscript x is DL for downlink and UL for uplink. N RB sc is the number of subcarriers per RB, and in 3GPP-based wireless communication systems, N RB scis typically 12. For a given antenna port p, subcarrier spacing configuration u, and transmission direction (DL or UL), there is one resource grid. The carrier bandwidth N for subcarrier spacing configuration u size,u grid is given to the UE by higher layer parameters (e.g., RRC parameters) from the network. Each element in the resource grid for antenna port p and subcarrier spacing configuration u is called a resource element (RE), and one complex symbol can be mapped to each RE. Each RE in the resource grid is uniquely identified by an index k in the frequency domain and an index l indicating the symbol position relative to a reference point in the time domain. In an NR system, an RB is defined by 12 consecutive subcarriers in the frequency domain. In an NR system, RBs can be classified into common resource blocks (CRBs) and physical resource blocks (PRBs). CRBs are numbered upwards from 0 in the frequency domain for the subcarrier spacing configuration u. The center of subcarrier 0 of CRB 0 for the subcarrier spacing configuration u coincides with 'Point A', which is a common reference point for the resource block grids. PRBs for subcarrier spacing u are defined within the bandwidth part (BWP) and range from 0 to N. size,u BWP,i -1, where i is the number of the bandwidth part. Common resource block n u CRB and bandwidth part i within physical resource block n PRB The relationship between the two is as follows: n u PRB = n u CRB +N start,u BWP,i , here N start,u BWP,iis a common resource block (BRB) whose bandwidth part starts relative to CRB 0. A BWP comprises multiple consecutive RBs in the frequency domain. For example, a BWP may be a given numeral u within a BWP i on a given carrier. i A subset of contiguous CRBs defined for a carrier. A carrier may include up to N (e.g., 5) BWPs. A UE may be configured to have one or more BWPs on a given component carrier. Data communication is performed through the activated BWPs, and only a predetermined number (e.g., 1) of BWPs configured for the UE may be activated on the carrier.

[0095] For each serving cell in a set of DL BWPs or UL BWPs, the network configures at least an initial DL BWP and one (if the serving configuration is configured with uplink) or two (if supplementary uplink is used) initial UL BWPs. The network may also configure additional UL and DL BWPs for the serving cell. For each DL BWP or UL BWP, the UE is provided with the following parameters for the serving cell: i) subcarrier spacing, ii) cyclic prefix, and iii) N start BWP = Offset RB with the assumption of 275 set and length L RB CRBN provided by the RRC parameter locationAndBandwidth, which indicates the resource indicator value (RIV) start BWP =O carrier +RB start and the number of contiguous RBs N size BWP =L RB , and the subcarrier spacing is provided by the RRC parameter offsetToCarrierO carrier; an index within the set of DL BWPs or UL BWPs; a set of BWP-common parameters and a set of BWP-specific parameters.

[0096] Switching between configured BWPs can occur using RRC signaling, DCI, an inactivity timer, or upon initiation of a random access. If an inactivity timer is configured for a serving cell, expiration of the inactivity timer associated with the serving cell switches the active BWP to the default BWP configured by the network.

[0097] Virtual resource blocks (VRBs) are defined within the bandwidth part and are numbered from 0 to N. size,u BWP,i Numbered from -1, where i is the number of the bandwidth part. VRBs are mapped to physical resource blocks (PRBs) according to interleaved or non-interleaved mapping. In some implementations, for non-interleaved VRB-to-PRB mapping, VRB n may be mapped to PRB n.

[0098] NR frequency bands are defined by two types of frequency ranges, FR1 and FR2, with FR2 also referred to as millimeter wave (mmW). The following table lists the frequency ranges in which NR can operate.

[0099]

[0100] Figure 6 illustrates physical channels used in a 3GPP-based communication system, which is an example of a wireless communication system, and a signal transmission / reception process using the channels.

[0101] When a UE is powered on again after being powered off or has been disconnected from a wireless communication system, it first searches for a suitable cell to camp on (search cell) and performs an initial cell search process, such as synchronizing with the cell or the BS of the cell (S11). During the initial cell search process, the UE receives a synchronization signal block (SSB) (also called an SSB / PBCH block) from the BS. The SSB includes a primary synchronization signal (PSS), a secondary synchronization signal (SSS), and a physical broadcast channel (PBCH). The UE synchronizes with the BS based on the PSS / SSS and obtains information such as a cell identity (ID). In addition, the UE can obtain broadcast information within the cell based on the PBCH. Meanwhile, the UE can check the downlink channel status by receiving a downlink reference signal (DL RS) during the initial cell search process.

[0102] A UE that has completed initial cell search can camp on the cell. After camping on the cell, the UE monitors the PDCCH on the cell and receives the PDSCH based on the downlink control information (DCI) carried by the PDCCH to obtain more specific system information (S12).

[0103] Thereafter, the UE may perform a random access procedure to complete access to the BS (S13 to S16). For example, in the random access procedure, the UE may transmit a preamble through a physical random access channel (PRACH) (S13) and receive a random access response (RAR) to the preamble through a PDCCH and a corresponding PDSCH (S14). If reception of the RAR for the UE fails, the UE may retry transmitting the preamble. In the case of contention-based random access, a contention resolution procedure (S16) may be performed, including transmission of a PUSCH based on UL resource allocation included in the RAR (S15) and reception of a PDCCH and a corresponding PDSCH.

[0104] The UE, which has performed the procedure described above, can then perform reception of PDCCH / PDSCH (S17) and transmission of PUSCH / PUCCH (S18) as a general uplink / downlink signal transmission process. The control information that the UE transmits to the BS is collectively referred to as uplink control information (UCI). UCI includes HARQ ACK / NACK (Hybrid Automatic Repeat and reQuest Acknowledgement / Negative-ACK) (also referred to as HARQ-ACK), scheduling request (SR), channel state information (CSI), etc. CSI may include a channel quality indicator (CQI), a precoding matrix indicator (PMI), and / or a rank indicator. UCI is generally transmitted through PUCCH, but may be transmitted through PUSCH when control information and traffic data must be transmitted simultaneously. Additionally, based on a request / instruction from the network, the UE can transmit UCI aperiodically via PUSCH.

[0105] Figure 7 illustrates SS / PBCH blocks (SSBs) on a cell.

[0106] In 3GPP-based systems, each SSB is associated with a beam. For example, during a half-frame, different SSBs can be transmitted in different spatial directions (using different beams spanning the cell's coverage area). The possible temporal positions of the SSBs within a half-frame are determined by the subcarriers, and the periodicity of the half-frames in which the SSBs are transmitted is set by the network. Multiple SSBs can be transmitted within the frequency span of a carrier. Different indices of the SSBs transmitted / detected on a cell can correspond to different BS (wide) Tx beams. Multi-beam operation in 3GPP-based systems is based on beam switching / beam scanning, which transmits / receives signals while changing the beam direction over time. Beam sweeping means that the transmission and reception point (TRP) (e.g., BS / cell) varies the beam (direction) of the radio signal over time. In this specification, beam and beam direction can be used interchangeably. SSB can be transmitted periodically using beam sweeping. In this case, the SSB index is implicitly linked to the SSB beam. The SSB beam can be changed on an SSB (index) basis or on an SSB (index) group basis. In the latter case, the SSB beam remains the same within the SSB (index) group. For example, referring to Fig. 7, the transmission beam direction of an SSB can be repeated in multiple consecutive SSBs. A set of SSBs is transmitted within a 5 ms half-frame. The set transmitted within a 5 ms half-frame of an SSB transmission is called an SSB burst set. The maximum number of SSB transmissions within an SSB burst set is L. max has a value of 4, 8, or 64 depending on the frequency band to which the carrier belongs. For example, the maximum number of SSBs in an SSB burst set, L maxcan be given as follows.

[0107] - For frequency range up to 3 GHz, L max = 4

[0108] - For frequency range from 3GHz to 6 GHz, L max = 8

[0109] - For frequency range from 6 GHz to 52.6 GHz, L max = 64

[0110] The number of SSBs actually transmitted can be set, with a maximum number L max It can be smaller.

[0111] If multi-beam transmission is not applied, the number of SSB beams is 1.

[0112] Figure 8 is a diagram illustrating the bitmaps used to indicate which SSBs are actually transmitted.

[0113] Within an SSB burst set, up to L SSBs can be transmitted, and the number / positions of the SSBs actually transmitted may vary depending on the BS / cell. The number / positions of the SSBs actually transmitted are used for rate matching and measurement, and information about the SSBs actually transmitted (e.g., RRC configuration ssb-PositionsInBurst) can be indicated as follows.

[0114] - In case of rate-matching: It can be indicated via UE-specific RRC signaling or RMSI. The UE-specific RRC signaling includes a full (e.g., length L) bitmap in both the frequency ranges below 6 GHz and above 6 GHz. On the other hand, the remaining minimum system information (RMSI) (i.e., SIB1) includes a full bitmap below 6 GHz and a compressed bitmap above 6 GHz as illustrated. Specifically, information about actually transmitted SSB can be indicated using a group bitmap (8 bits) and an intra-group bitmap (8 bits). Here, resources (e.g., resource elements (REs)) indicated via the UE-specific RRC signaling or RMSI are reserved for SSB transmission, and PDSCH / PUSCH, etc. can be rate-matched considering SSB resources.

[0115] - For measurement purposes: When in RRC_CONNECTED mode, the network (e.g., BS) can indicate the set of SSBs to be measured within the measurement interval. The SSB set can be indicated per frequency layer. If there is no indication regarding the SSB set, the default SSB set is used. The default SSB set includes all SSBs within the measurement interval. The SSB set can be indicated using the full (e.g., length L) bitmap in RRC signaling. When in RRC_IDLE mode, the default SSB set is used.

[0116] Figure 9 illustrates a process for acquiring system information (SI). A UE can acquire AS / NAS information through the SI acquisition process. The SI acquisition process can be applied to UEs in the RRC_IDLE state, the RRC_INACTIVE state, and the RRC_CONNECTED state. RRC_CONNECTED is a state in which the UE has established an RRC connection with the network. RRC_IDLE is a state in which the UE is not registered in a specific cell and thus does not receive the access stratum (AS) context or other information received from the network. RRC_INACTIVE is a state in which the UE can move within an area established by the radio access network (RAN, e.g., BS(s)) without notifying the RAN while remaining in CM-CONNECTED, which is a state in which the UE has a signaling connection with the core network for connection management (CM). CM_CONNECTED is a state in which the UE has a non-access stratum (NAS) signaling connection with the core network, and CM_IDLE is a state in which the UE does not have any NAS signaling.

[0117] In a 3GPP-based system, SI can be divided into a master information block (MIB) and multiple system information blocks (SIBs). The MIB and multiple SIBs can be further divided into minimum SI and other SI. Here, minimum SI can be composed of MIB and System Information Block 1 (SIB1), and includes basic information required for initial connection and information for acquiring other SI. Here, SIB1 can be referred to as remaining minimum system information (RMSI). For more details, see the following.

[0118] - The MIB is always transmitted on the BCH with a periodicity of 80 ms and repetitions made within 80 ms. The MIB contains information / parameters related to the reception of SIB1 and is transmitted over the PBCH of SSB. During initial cell selection, the UE assumes that half-frames with SSB(s) repeat with a period of 20 ms. Based on the MIB, the UE can check whether a control resource set (CORESET) for the Type0-PDCCH common search space exists. The Type0-PDCCH common search space is a type of PDCCH search space and is used to transmit the PDCCH that schedules the SI message. If a Type0-PDCCH common search space exists, the UE can determine (i) multiple consecutive RBs and one or more consecutive symbols that constitute a CORESET and (ii) PDCCH occasions (i.e., time domain locations for PDCCH reception) based on information in the MIB (e.g., pdcch-ConfigSIB1). If a Type0-PDCCH common search space does not exist, pdcch-ConfigSIB1 provides information about frequency locations where SSB / SIB1 exists and frequency ranges where SSB / SIB1 does not exist.

[0119] - SIB1 is transmitted on the downlink shared channel (DL-SCH) with a periodicity of 160 ms and a variable transmission repetition period within 160 ms. The default transmission repetition period of SIB1 is 20 ms, but the actual transmission repetition period may vary depending on the network implementation. SIB1 contains information related to the availability and scheduling (e.g., transmission period, SI window size) of the remaining SIBs (hereinafter, SIBx, where x is an integer greater than or equal to 2). For example, SIB1 may indicate whether SIBx is broadcast periodically or provided on-demand upon request of the UE. If SIBx is provided on-demand, SIB1 may contain information necessary for the UE to perform an SI request. SIB1 is a cell-specific SIB. The PDCCH scheduling SIB1 is transmitted through the Type0-PDCCH common search space, and SIB1 is transmitted through the PDSCH indicated by the PDCCH.

[0120] - SIBx is included in SI messages and transmitted over the PDSCH. Each SI message is transmitted within a time window (i.e., SI window) that occurs periodically according to the SI scheduling information provided by SIB1.

[0121] Figure 10 illustrates a random access process that may be applied to implementation(s) of the present specification. In particular, Figure 10(a) illustrates a four-step random access process, and Figure 10(b) illustrates a two-step random access process.

[0122] The random access procedure can be used for various purposes, such as initial access, uplink synchronization adjustment, resource allocation, handover, reconfiguration of radio links after radio link failure, and position measurement. The random access procedure is classified into a contention-based procedure and a dedicated (i.e., non-contention-based) procedure. The contention-based random access procedure is commonly used, including initial access, while the dedicated random access procedure is used for handovers, when downlink data arrives at the network, and to reestablish uplink synchronization in the case of position measurement. In the contention-based random access procedure, the UE randomly selects a random access (RA) preamble. Therefore, multiple UEs can transmit the same RA preamble simultaneously, necessitating subsequent contention resolution. In contrast, in the dedicated random access procedure, the UE uses an RA preamble uniquely assigned to the UE by the BS. Therefore, the UE can perform the random access procedure without collisions with other UEs.

[0123] Referring to Fig. 10(a), the contention-based random access process includes the following four steps. Hereinafter, the messages transmitted in steps 1 through 4 may be referred to as Msg1 through Msg4, respectively.

[0124] - Step 1: The UE transmits an RA preamble via PRACH.

[0125] - Step 2: The UE receives a random access response (RAR) from the BS via PDSCH.

[0126] - Step 3: The UE transmits UL data to the BS via PUSCH based on the RAR. Here, the UL data includes layer 2 and / or layer 3 messages.

[0127] - Step 4: The UE receives a contention resolution message from the BS via PDSCH.

[0128] A UE can receive information about random access from a BS through system information. For example, information about RACH occasions associated with SSBs on a cell can be provided through the system information. The UE can select an SSB among the SSBs received on the cell whose reference signal received power (RSRP) measured based on the SSB exceeds a threshold, and transmit an RA preamble through a PRACH associated with the selected SSB. For example, if random access is required, the UE transmits Msg1 (e.g., preamble) to the BS on the PRACH. The BS can distinguish each random access preamble through the time / frequency resource (RA Occasion, RO) on which the random access preamble was transmitted and the random access preamble index (Preamble Index, PI). When the BS receives a random access preamble from the UE, the BS transmits a RAR message to the UE on the PDSCH. To receive a RAR message, the UE monitors a cyclic redundancy check (CRC) masked L1 / L2 control channel (PDCCH) with a Random Access-RNTI (RA-RNTI), which contains scheduling information for the RAR message, within a preset time window (e.g., ra-ResponseWindow). When scheduling information is received through the PDCCH masked with the RA-RNTI, the UE can receive an RAR message from a PDSCH indicated by the scheduling information. Thereafter, the UE determines whether an RAR for itself is included in the RAR message. Whether an RAR for itself exists can be determined by whether a Random Access preamble ID (RAPID) for a preamble transmitted by the UE exists. The index of the preamble transmitted by the UE and the RAPID may be the same.The RAR includes a corresponding random access preamble index, timing offset information for UL synchronization (e.g., timing advance command (TAC), UL scheduling information for Msg3 transmission (e.g., UL grant), and UE temporary identification information (e.g., Temporary-C-RNTI, TC-RNTI). The UE receiving the RAR transmits Msg3 through the PUSCH according to the UL scheduling information and timing offset value in the RAR. Msg3 may include the ID of the UE (or the global ID of the UE). In addition, Msg3 may include information related to an RRC connection request for initial access to the network (e.g., an RRCSetupRequest message). After receiving Msg3, the BS transmits Msg4, which is a contention resolution message, to the UE. If the UE receives the contention resolution message and the contention is successfully resolved, the TC-RNTI is changed to the C-RNTI. Msg4 includes the ID of the UE. And / or RRC connection related information (e.g., RRCSetup message) may be included. If the information transmitted via Msg3 does not match the information received via Msg4, or if Msg4 is not received for a certain period of time, the UE may consider contention resolution to have failed and retransmit Msg3.

[0129] Meanwhile, the dedicated random access process includes the following three steps. Hereinafter, the messages transmitted in steps 0 to 2 may be referred to as Msg0 to Msg2, respectively. The dedicated random access process may be triggered in the UE by the BS using a PDCCH (hereinafter, PDCCH order) for commanding the transmission of an RA preamble.

[0130] - Step 0: BS allocates RA preamble to UE through dedicated signaling.

[0131] - Step 1: The UE transmits an RA preamble via PRACH.

[0132] - Step 2: The UE receives RAR via PDSCH from the BS.

[0133] The operation of steps 1 and 2 of the dedicated random access process may be identical to steps 1 and 2 of the contention-based random access process.

[0134] NR systems may require lower latency than traditional systems. Furthermore, a four-step random access process may be undesirable, especially for latency-sensitive services such as URLLC. A low-latency random access process may be required in various scenarios within NR systems. When implementing implementations of this specification in conjunction with a random access process, implementations of this specification may be implemented in conjunction with the following two-step random access process to reduce the latency of the random access process.

[0135] Referring to Fig. 10(b), the two-step random access process may be composed of two steps: transmission of MsgA from a UE to a BS and transmission of MsgB from the BS to the UE. The MsgA transmission may include transmission of an RA preamble via a PRACH and transmission of an UL payload via a PUSCH. In the MsgA transmission, the PRACH and PUSCH may be transmitted using time division multiplexing (TDM). Alternatively, in the MsgA transmission, the PRACH and PUSCH may be transmitted using frequency division multiplexing (FDM).

[0136] A BS that receives MsgA can transmit MsgB to the UE. MsgB can include an RAR for the UE.

[0137] An RRC connection request related message (e.g., an RRCSetupRequest message) requesting to establish a connection between the RRC layer of the BS and the RRC layer of the UE may be transmitted in the payload of MsgA. In this case, MsgB may be used to transmit RRC connection related information (e.g., an RRCSetup message). Alternatively, the RRC connection request related message (e.g., an RRCSetupRequest message) may be transmitted via a PUSCH transmitted based on a UL grant in MsgB. In this case, the RRC connection related information (e.g., an RRCSetup message) related to the RRC connection request may be transmitted via a PDSCH associated with the PUSCH transmission after the PUSCH transmission based on MsgB.

[0138] Below, the physical channels that can be used in 3GPP-based wireless communication systems are described in more detail.

[0139] The PDCCH carries DCI. For example, the PDCCH (i.e., DCI) carries the transmission format and resource allocation of the downlink shared channel (DL-SCH), resource allocation information for the uplink shared channel (UL-SCH), paging information for the paging channel (PCH), system information on the DL-SCH, resource allocation information for control messages of a layer (hereinafter, upper layer) located above the physical layer in the protocol stacks of the UE / BS, such as a random access response (RAR) transmitted on the PDSCH, transmission power control commands, activation / release of configured scheduling (CS), etc. The DCI that includes resource allocation information for the DL-SCH is also called PDSCH scheduling DCI, and the DCI that includes resource allocation information for the UL-SCH is also called PUSCH scheduling DCI. The DCI includes a cyclic redundancy check (CRC), and the CRC is masked / scrambled with various identifiers (e.g., radio network temporary identifier (RNTI)) depending on the owner or intended use of the PDCCH. For example, if the PDCCH is for a specific UE, the CRC is masked with the UE identifier (e.g., cell RNTI (C-RNTI)). If the PDCCH is for paging, the CRC is masked with the paging RNTI (P-RNTI). If the PDCCH is for system information (e.g., system information block (SIB)), the CRC is masked with the system information RNTI (SI-RNTI). If the PDCCH is for a random access response, the CRC is masked with the random access RNTI (RA-RATI).

[0140] When a PDCCH on one serving cell schedules a PDSCH or PUSCH on another serving cell, this is called cross-carrier scheduling. Cross-carrier scheduling using the carrier indicator field (CIF) can allow the PDCCH of a serving cell to schedule resources on another serving cell. On the other hand, when a PDSCH on a serving cell schedules a PDSCH or PUSCH on the serving cell, this is called self-carrier scheduling. When cross-carrier scheduling is used in a cell, the BS can provide the UE with information about the cell that schedules the cell. For example, the BS can provide the UE with information about whether the serving cell is scheduled by a PDCCH on another (scheduling) cell or by the serving cell, and if the serving cell is scheduled by another (scheduling) cell, which cell signals downlink assignments and uplink grants for the serving cell. In this specification, a cell that carries a PDCCH is called a scheduling cell, and a cell in which transmission of a PUSCH or PDSCH is scheduled by DCI included in the PDCCH, i.e., a cell that carries a PUSCH or PDSCH scheduled by the PDCCH, is called a scheduled cell.

[0141] The PDSCH is a physical layer DL channel for DL ​​data transport. PDSCH carries downlink data (e.g., DL-SCH transport blocks) and employs modulation methods such as Quadrature Phase Shift Keying (QPSK), 16 Quadrature Amplitude Modulation (QAM), 64 QAM, and 256 QAM. Transport blocks (TBs) are encoded to generate codewords. A PDSCH can carry up to two codewords. Scrambling and modulation mapping are performed for each codeword, and the modulation symbols generated from each codeword can be mapped to one or more layers. Each layer is mapped to radio resources along with the DMRS, generating an OFDM symbol signal and transmitting it through the corresponding antenna port.

[0142] A UE must have uplink resources available to it for UL-SCH data transmission, and downlink resources available to it for DL-SCH data reception. Uplink and downlink resources are assigned to the UE through resource allocation by the BS. Resource allocation may include time domain resource allocation (TDRA) and frequency domain resource allocation (FDRA). In this specification, uplink resource allocation is also referred to as uplink grant, and downlink resource allocation is also referred to as downlink assignment. An uplink grant is dynamically received by the UE on the PDCCH or within the RAR, or is semi-persistently configured to the UE by RRC signaling from the BS. A downlink assignment is dynamically received by the UE on the PDCCH, or is semi-persistently configured to the UE by RRC signaling from the BS.

[0143] In UL, the BS can dynamically allocate uplink resources to the UE via PDCCH(s) addressed to a cell radio network temporary identifier (C-RNTI). The UE monitors the PDCCH(s) to find possible uplink grant(s) for UL transmission. Furthermore, the BS can allocate uplink resources to the UE using the configured grant(s). Two types of configured grants can be used: Type 1 and Type 2. For Type 1, the BS directly provides the configured uplink grant (including the periodicity) via RRC signaling. For Type 2, the BS can configure the period of the RRC configured uplink grant via RRC signaling, and signal and activate or deactivate the configured uplink grant via a PDCCH addressed to a configured scheduling RNTI (CS-RNTI). For example, for Type 2, a PDCCH addressed to CS-RNTI implicitly indicates that the corresponding uplink grant can be reused according to a period set by RRC signaling until it is deactivated.

[0144] In DL, the BS can dynamically allocate downlink resources to the UE via PDCCH(s) addressed with the C-RNTI. The UE monitors the PDCCH(s) to discover possible downlink assignments. Additionally, the BS can allocate downlink resources to the UE using semi-static scheduling (SPS). The BS can set the period of the configured downlink assignments via RRC signaling, and signal and activate or deactivate the configured downlink assignments via the PDCCH addressed with the CS-RNTI. For example, a PDCCH addressed with the CS-RNTI implicitly indicates that the corresponding downlink assignment can be reused according to the period set by the RRC signaling until it is deactivated.

[0145] Figure 11 illustrates an example of PDSCH time domain resource allocation by PDCCH and an example of PUSCH time domain resource allocation by PDCCH.

[0146] The DCI carried by the PDCCH for scheduling the PDSCH or PUSCH includes a time domain resource assignment (TDRA) field, which provides a value m for a row index m+1 of an allocation table for the PDSCH or PUSCH. A predefined default PDSCH time domain allocation is applied as the allocation table for the PDSCH, or a PDSCH time domain resource allocation table configured by the BS through RRC signaling pdsch-TimeDomainAllocationList is applied as the allocation table for the PDSCH. A predefined default PUSCH time domain allocation is applied as the allocation table for the PUSCH, or a PUSCH time domain resource allocation table configured by the BS through RRC signaling pushch-TimeDomainAllocationList is applied as the allocation table for the PUSCH. The PDSCH time domain resource allocation table to be applied and / or the PUSCH time domain resource allocation table to be applied may be determined according to fixed / predefined rules (e.g., see 3GPP TS 38.214).

[0147] In the PDSCH time domain resource configurations, each indexed row defines a DL allocation-to-PDSCH slot offset K0, a start and length indicator value SLIV (or directly a starting position (e.g., a starting symbol index S) and an allocation length (e.g., a number of symbols L) of a PDSCH within a slot), and a PDSCH mapping type. In the PUSCH time domain resource configurations, each indexed row defines a UL grant-to-PUSCH slot offset K2, a starting position (e.g., a starting symbol index S) and an allocation length (e.g., a number of symbols L) of a PUSCH within a slot, and a PUSCH mapping type. K0 for PDSCH or K2 for PUSCH indicates the difference between a slot with a PDCCH and a slot with a PDSCH or PUSCH corresponding to the PDCCH. SLIV is a joint indication of a starting symbol S relative to the start of a slot with a PDSCH or PUSCH and the number L of consecutive symbols counted from the symbol S. For PDSCH / PUSCH mapping type, there are two mapping types: one is mapping type A and the other is mapping type B. For PDSCH / PUSCH mapping type A, a demodulation reference signal (DMRS) is mapped to a PDSCH / PUSCH resource at the beginning of a slot, and one or two symbols of the PDSCH / PUSCH resource can be used as DMRS symbol(s) depending on other DMRS parameters. For example, for PDSCH / PUSCH mapping type A, the DMRS is located at the third symbol (symbol #2) or the fourth symbol (symbol #3) in a slot depending on RRC signaling. For PDSCH / PUSCH mapping type B, the DMRS is mapped based on the first OFDM symbol of the PDSCH / PUSCH resource, and one or two symbols from the first symbol of the PDSCH / PUSCH resource can be used as DMRS symbol(s) depending on other DMRS parameters.For example, in the case of PDSCH / PUSCH mapping type B, DMRS is located in the first symbol allocated for PDSCH / PUSCH. In this specification, PDSCH / PUSCH mapping type may be referred to as mapping type or DMRS mapping type. For example, in this specification, PUSCH mapping type A may be referred to as mapping type A or DMRS mapping type A, and PUSCH mapping type B may be referred to as mapping type B or DMRS mapping type B.

[0148] The above scheduling DCI includes a frequency domain resource assignment (FDRA) field that provides allocation information regarding resource blocks used for PDSCH or PUSCH. For example, the FDRA field provides the UE with information regarding the cell for PDSCH or PUSCH transmission, information regarding the BWP for PDSCH or PUSCH transmission, and information regarding resource blocks for PDSCH or PUSCH transmission.

[0149] A control resource set (CORESET), which is a set of time-frequency resources for which a UE can monitor PDCCH, may be defined and / or configured. A CORESET consists of a set of physical resource blocks (PRBs) with a duration of one to three OFDM symbols. The PRBs constituting the CORESET and the CORESET duration may be provided to the UE via higher layer (e.g., RRC) signaling. Within the configured CORESET(s), a set of PDCCH candidates is monitored according to the corresponding search space sets. In this specification, monitoring implies decoding (aka blind decoding) each PDCCH candidate according to the monitored DCI formats. The master information block (MIB) on the PBCH provides the UE with parameters (e.g., CORESET#0 configuration) for monitoring the PDCCH for scheduling the PDSCH carrying the system information block 1 (SIB1). The PBCH may also indicate that there is no associated SIB1, in which case the UE may be instructed on other frequencies to search for the SSB associated with SIB1, as well as a frequency range in which it can assume that there is no SSB associated with SSB1. At least CORESET#0, which is the CORESET for scheduling SIB1, may be configured via the MIB or dedicated RRC signaling.

[0150] More than one CORESET may be configured for a UE, and multiple CORESETs may overlap in the time / frequency domain.

[0151] The set of PDCCH candidates monitored by the UE is defined in terms of PDCCH search space sets. The search space set may be a common search space (CSS) set or a UE-specific search space (USS) set. Each CORESET configuration is associated with one or more search space sets, and each search space set is associated with one CORESET configuration.

[0152] A set of PDCCH candidates may be monitored in one or more CORESETs on an active DL BWP on each activated serving cell for which PDCCH monitoring is configured, where monitoring implies receiving each PDCCH candidate and decoding it according to the monitored DCI formats.

[0153] SS sets can be configured via system information (e.g., MIB) or UE-specific higher layer (e.g., RRC) signaling. Each DL BWP of a serving cell can have up to S (e.g., 10) SS sets configured. For example, the following parameters / information can be provided for each SS set. Each SS set is associated with one CORESET, and each CORESET configuration can be associated with one or more SS sets.

[0154] - searchSpaceId: Indicates the ID of the SS set.

[0155] - controlResourceSetId: Indicates the CORESET associated with the SS set.

[0156] - monitoringSlotPeriodicityAndOffset: Indicates the PDCCH monitoring period period (in slot units) and the PDCCH monitoring period offset (in slot units).

[0157] - monitoringSymbolsWithinSlot: Indicates the first OFDMA symbol(s) for PDCCH monitoring within the slot where PDCCH monitoring is configured. It is indicated through a bitmap, and each bit corresponds to each OFDMA symbol within the slot. The MSB of the bitmap corresponds to the first OFDM symbol within the slot. The OFDMA symbol(s) corresponding to the bit(s) with a bit value of 1 corresponds to the first symbol(s) of the CORESET within the slot.

[0158] - nrofCandidates: AL={1, 2, 4, 8, 16} indicates the number of PDCCH candidates (e.g., one of 0, 1, 2, 3, 4, 5, 6, 8).

[0159] - searchSpaceType: Indicates whether the SS type is CSS or USS.

[0160] - DCI format: Indicates the DCI format of the PDCCH candidate.

[0161] Based on the CORESET / SS set configuration, the UE can monitor PDCCH candidates in one or more SS sets within a slot. The occasions (e.g., time / frequency resources) during which PDCCH candidates should be monitored are defined as PDCCH (monitoring) occasions. One or more PDCCH (monitoring) occasions can be configured within a slot.

[0162] UE uses DRX to reduce power consumption. UE operating based on DRX repeats ON / OFF for reception operation. The features of DRX utilized for the purpose of reducing unnecessary power consumption of UE are as follows. DRX defines a structure for UE in RRC_IDLE state where RRC connection between UE and BS is not established (hereinafter referred to as I-DRX) and a structure for UE in RRC_CONNECTED state where RRC connection between UE and BS is established (hereinafter referred to as C-DRX). Both DRX structures are designed to reduce unnecessary power consumption in other periods by defining a period (e.g., active time period or on-duration period) in which UE can expect reception of DL signals to occur periodically. For reference, in the case of C-DRX, the start position of On-duration occurs periodically in the Rel-16 standard, and the size of the cycle that can be configured at this time (i.e., DRX cycle) can be determined / set through upper layer signaling, such as RRC signaling, provided by the BS to the UE.

[0163] Figure 12 illustrates a discontinuous reception (DRX) operation. In particular, Figure 12 illustrates a DRX cycle for a UE in RRC_CONNECTED state.

[0164] Referring to FIG. 12, a DRX cycle consists of an ON period and an Opportunity for DRX. A DRX cycle defines a time interval in which an ON period is periodically repeated, followed by a possible period of inactivity. The ON period represents a time interval during which the UE performs PDCCH monitoring to receive a PDCCH. When DRX is configured, the UE performs PDCCH monitoring during the ON period. If a PDCCH is successfully detected during PDCCH monitoring, the UE starts an inactivity timer and remains awake. On the other hand, if no PDCCH is successfully detected during PDCCH monitoring, the UE enters a sleep state after the ON period ends. Therefore, when DRX is configured, the UE may perform PDCCH monitoring / reception discontinuously in the time domain when performing a process and / or method according to the implementation(s) of this specification. For example, when DRX is configured, the PDCCH reception occasion (e.g., slot having PDCCH search space) in this specification may be configured discontinuously according to the DRX configuration. On the other hand, when DRX is not configured, the UE may perform PDCCH monitoring / reception continuously in the time domain. For example, when DRX is not configured, the PDCCH reception occasion (e.g., slot having PDCCH search space) may be configured continuously. On the other hand, regardless of whether DRX is configured, PDCCH monitoring may be restricted in the time period configured as the measurement gap. DRX configuration information is received via upper layer (e.g., RRC) signaling, and whether DRX is turned on / off is controlled by the DRX command of the MAC layer. When DRX is configured, the UE may perform PDCCH monitoring discontinuously, as illustrated in FIG. 12.

[0165] The following table illustrates the UE processes related to DRX. Referring to the following table, DRX configuration information is received via upper layer (e.g., RRC) signaling, and DRX ON / OFF is controlled by the DRX command of the MAC layer. When DRX is configured, the UE can perform PDCCH monitoring discontinuously, as illustrated in FIG. 12.

[0166]

[0167] Here, MAC-CellGroupConfig contains configuration information required to set MAC parameters for a cell group. MAC-CellGroupConfig may also contain configuration information related to DRX. For example, MAC-CellGroupConfig may contain DRX-related information as follows.

[0168] - Value of drx-onDurationTimer: Sets the duration at the start of the DRX cycle.

[0169] - Value of drx-SlotOffset: Sets the delay before starting drx-onDurationTimer.

[0170] - Value of drx-InactivityTimer: Sets the period after which a PDCCH epoch indicates a new UL or DL ​​transmission to the MAC entity.

[0171] - Value of drxRetransmissionTimerDL (per DL HARQ process except for the broadcast process): Sets the maximum duration until a DL retransmission is received.

[0172] - Value of drxRetransmissionTimerUL (per UL HARQ process): Sets the maximum duration until a grant for UL retransmission is received.

[0173] - Value of drx-HARQ-RTT-TimerDL (per DL HARQ process except for the broadcast process): Sets the maximum period of time after a DL initial transmission is received until a DL assignment for HARQ retransmission is received.

[0174] - Value of drx-HARQ-RTT-TimerUL (per UL HARQ process): Sets the maximum period from when a grant for UL initial transmission is received until a grant for UL retransmission is received.

[0175] - drx-LongCycleStartOffset: Sets the Long DRX cycle and drx-StartOffset, which defines the subframe where the Long and Short DRX cycles start.

[0176] - drx-ShortCycle (optional): Sets the short DRX cycle.

[0177] - drx-ShortCycleTimer (optional): Sets the duration for which the UE should follow the Short DRX cycle. For example, a value in multiples of the Short DRX cycle can be set by drx-CylceTimer. For example, the value of n can correspond to n*drx-ShortCycle.

[0178] A UE may perform PDCCH monitoring on serving cells within a DRX group when the DRX group is within its active time. Here, a DRX group is a group of serving cells configured by RRC and having the same DRX active time. Here, the active time is a total duration for which the UE monitors the PDCCH, and may include an ON period of a DRX cycle, a time for which the UE performs continuous reception while an inactivity timer has not expired, and a time for which the UE performs continuous reception while waiting for a retransmission opportunity. For example, when DRX is configured, the active time for serving cells within a DRX group is i) while drx-onDurationTimer or drx-InactivityTimer configured for the DRX group is running; or ii) while drx-RetransmissionTimerDL or drx-RetransmissionTimerUL is running on any serving cell within the DRX group; or ra-ContentionResoultionTimer or msgB-RsponseWindow is running; or a PDCCH indicating a new transmission addressed to a C-RNTI addressed to the MAC entity of the UE is not received after successful reception of a random access response to a random access preamble that is not selected by the MAC entity among the contention-based random access preambles.

[0179] A UE can be configured with one or more DRX groups via RRC signaling from a BS. For example, if two DRX groups are configured, each serving cell is uniquely assigned to one of the two DRX groups. The DRX parameters drx-onDurationTimer and drx-InactivityTimer are configured separately for each DRX group, and the DRX parameters drx-SlotOffset, drx-RetransmissionTimerDL, drx-RetransmissionTimerUL, drx-LongCycleStartOffset, drx-ShortCycle (optional), drx-ShortCycleTimer (optional), drx-HARQ-RTT-TimerDL, and drx-HARQ-RTT-TimerUL are common to the DRX groups. Since each serving cell belongs to only one of the DRX groups, and the DRX parameters drx-onDurationTimer and drx-InactivityTimer are set for each DRX group, and the remaining DRX parameters are common to the DRX groups, it can be said that a serving cell is associated with only one set of DRX parameters.

[0180] Figure 13 illustrates a case where a Long DRX cycle and a Short DRX cycle are set. In particular, Figure 13 illustrates a case where drx-ShortCycleTimer is set to 2.

[0181] A BS can configure a Long DRX cycle and an additional Short DRX cycle that is shorter than the Long DRX cycle. If a Short DRX cycle is not configured, the UE follows the Long DRX cycle. When configuring a Short DRX cycle, the BS sets the duration of the Long DRX cycle to be a positive integer multiple of the Short DRX cycle. The same onDurationTimer value is configured for the Long DRX cycle and the Short DRX cycle. If there is no data activity during the ON period of the Long DRX cycle (e.g., no PDCCH reception), the UE follows the Long DRX cycle as if the Short DRX cycle is not configured. If there is data activity during the ON period of the Long DRX cycle, for example, while drx-onDurationTimer is running, the UE switches to the Short DRX cycle and follows the Short DRX cycle for a certain period of time (e.g., while drx-ShortCycleTimer is running). At this time, the start of the ON period in the Short DRX cycle is determined by drx-StartOffset and drx-SlotOffset, just like the Long DRX cycle. Referring to FIG. 13, if there is no data activity during the time following the Short DRX cycle, for example, if there is no data activity during the period defined by drx-ShortCycleTimer*drx-ShortCycle, the UE switches to the Long DRX cycle after drx-ShortCycleTimer Short DRX cycles.

[0182] Energy conservation of base stations (BSs) is a key consideration in wireless communication systems, including 3GPP, as it can contribute to building eco-friendly networks by reducing carbon emissions and reducing the operational expenditure (OPEX) of telecommunications operators. In particular, the introduction of 5G communications will require higher transmission rates, necessitating BSs to be equipped with more antennas and provide services over wider bandwidths and frequency bands. Consequently, recent studies have shown that BS energy costs have reached up to 20% of total OPEX. This heightened interest in BS energy conservation led to the approval of a new study item, "Study on Network Energy Savings," in 3GPP NR Release 18. For example, to improve the energy saving capability of BS from the perspective of transmission and reception, the study investigates how to achieve dynamic and / or semi-static and finer granularity adaptation of transmission and / or reception to more efficient operation with one or more network energy saving techniques in time, frequency, space and power domains using potential assistance / feedback of UE and potential UE assistance information.

[0183] The following enhancement techniques may be considered:

[0184] > Specify SSB-less SCell operation for inter-band CA for FR1 and co-located cells, where a UE measures SSB transmitted on PCell or another SCell for an SCell's time / frequency synchronization (including downlink AGC), and L1 / L3 measurements, including potential enhancement on SCell activation procedures if necessary.

[0185] > Specify enhancement on cell DTX / DRX mechanism including the alignment of cell DTX / DRX and UE DRX in RRC_CONNECTED mode, and inter-node information exchange on cell DTX / DRX

[0186] > Specify the following techniques in spatial and power domains:

[0187] >> Specify necessary enhancements on CSI and beam management related procedures including measurement and report, and signaling to enable efficient adaptation of spatial elements (e.g., antenna ports, active transceiver chains).

[0188] >> Specify necessary enhancements on CSI-related procedures including measurement and report, and signaling to enable efficient adaptation of power offset values ​​between PDSCH and CSI-RS.

[0189] > Specify mechanism(s) to prevent legacy UEs camping on cells adopting the Rel-18 NES techniques, if necessary.

[0190] > Specify conditional handover (CHO) procedure enhancement(s) in case source / target cell is in NES mode.

[0191] > Specify inter-node beam activation and enhancements on restricting paging in a limited area.

[0192] > Specify the corresponding radio resource management / radio frequency (RRM / RF) core requirements, if necessary, for the above features.

[0193] After the UE initially accesses the BS and enters connected mode, it must continuously perform PDCCH monitoring to check if there is a transmission scheduled for it in each configured search space. However, if this scheduling is not always present, the UE may quickly drain its battery due to unnecessary PDCCH monitoring every time. Therefore, the BS can set the UE to an ON duration during which it must perform PDCCH monitoring and an OFF duration during which it does not need to perform PDCCH monitoring. In other words, the BS can set the UE to connected mode discontinuous reception (C-DRX) to save power. From the BS's perspective, the UE's C-DRX can also help save energy for the BS. For example, during the C-DRX OFF period of a specific UE, the BS does not need to transmit the PDCCH of the specific UE, so the BS can use its resources (e.g., radio resources during the C-DRX OFF period of the specific UE) for other purposes or obtain energy saving (ES) benefits through DTX / DRX. However, since the UE can transmit without restriction as needed on pre-configured resources (e.g., SR, PUCCH, CG PUSCH, etc.) even during the OFF period, the BS must wait for UL reception of the UE, which may be transmitted at any time. In addition, since C-DRX is configured UE-specifically, the DRX cycles or ON / OFF periods between UEs within a cell (or BS) are not aligned. Therefore, if the ON periods of UEs are set in a time division multiplexing (TDM) format, it may be difficult to expect ES gain because the BS cannot sleep for PDCCH transmission for each ON period of each UE within the cell (or BS).

[0194] Therefore, in some implementations of this specification, the BS can save energy by turning OFF transmission / reception of specific signals / channels during inactive periods through cell-specific DTX / DRX configuration with alternating active and inactive periods, similar to UE C-DRX. In order for a UE to transmit or receive data, it must establish a connection with the BS and enter RRC_CONNECTED mode / state. If there is no activity of the UE for a certain period of time, the BS can reduce the power consumption of the UE by transitioning the UE to RRC_IDLE mode / state. Since the UE must transition back to connected mode whenever transmission / reception is required, RRC signaling occurs during the process of the UE establishing an RRC connection, and latency is increased due to this RRC signaling. If a UE needs to transmit small data frequently, the transition between RRC_IDLE and RRC_CONNECTED will not only increase the delay but also increase the signaling overhead. To reduce the BS signaling overhead and the delay in data transmission / reception due to these frequent RRC state changes, a new state called RRC_INACTIVE is introduced. The INACTIVE mode (i.e., RRC_INACTIVE mode) can perform data transmission / reception operations quickly and with low signaling overhead by suspending the RRC connection. In some implementations of the present specification described below, a method for configuring parameters of cell DTX / DRX configuration, a method for activation, and a method(s) for transmission / reception of signals and channels affected by cell DTX / DRX operation are described to apply cell DTX / DRX operation not only to UEs in connected mode but also to UE(s) in IDLE mode and UE(s) in INACTIVE mode.

[0195] A UE in connected mode monitors PDCCH during periodic ON periods to check if there is UL / DL to transmit / receive, and when a PDCCH is received, performs DL reception or UL transmission according to the instructions of the PDCCH. In the case of UL, the UE can wake up from sleep mode and transmit a scheduling request (SR) if there is data to be sent in the UL buffer, regardless of C-DRX. A UE in idle mode periodically performs paging monitoring, and if the UE is not the target UE of the paging, it can operate in idle mode (idle mode DRX (i.e., I-DRX)) which returns to sleep mode. Here, the UE operating in sleep mode can mean performing SR transmission “regardless of the active time determined by C-DRX” or “even in a period other than the active time determined by C-DRX.” In C-DRX operation, a time period consisting of an ON period and an OFF period is repeated, which is called a DRX cycle. The length of a DRX cycle can be defined as from the start of an ON period to before the next ON period, and a DRX cycle can be divided into a Long DRX cycle and a Short DRX cycle. If the length of the DRX cycle becomes longer, if the BS has a PDSCH to send immediately after the end of a specific ON period of the UE, it must wait until the next ON period of the UE, which may increase latency. From the BS's perspective, Since the UE does not transmit periodic CSI (P-CSI) or sounding reference signal (SRS) during the OFF period, the resource utilization can be improved by allocating the resource (i.e., the resource for P-CSI or SRS transmission) to another UE.Additionally, the BS may also operate in energy saving mode to save power during the UE's OFF period.

[0196] In relation to C-DRX, the BS may instruct the UE to enter DRX sleep mode directly without operating in active mode until the end of the ON period via the DRX command MAC control element (CE). For example, the BS may instruct the UE to terminate the current active time and enter the DRX cycle directly. If only the Long DRX cycle is configured for the UE, the UE may operate in the Long DRX cycle (based on the DRX command MAC control element (CE)). If both the Long DRX cycle and the Short DRX cycle are configured, the UE will enter the Short DRX cycle directly after receiving the DRX command MAC CE. In addition, if the BS provides the Long DRX command MAC CE, the UE may operate in the Long DRX cycle even if the Short DRX cycle is configured. Additionally, BS can control / change the starting point of the Long DRX cycle via the RRC parameter drx-LongCycleStartOffset, which is used to set the Long DRX cycle and the drx-StartOffset, which defines the subframe in which the Long and Short DRX cycles start. Here, the value of the RRC parameter drx-LongCycleStartOffset is defined in ms units so that the Long DRX cycle can start at the slot boundary. Additionally, the starting point of the ON period can be set at slot level granularity via another RRC parameter drx-SlotOffset. In this case, the relative position of the ON period is defined by applying the slot offset indicated (by drx-SlotOffset) with respect to the reference point indicated by drx-LongCycleStartOffset.

[0197] By waking up the UE only during the ON period and monitoring the presence of PDCCH transmitted to itself through C-DRX configuration, energy can be saved compared to continuously (e.g., at every slot) monitoring the PDCCH. In addition, if the BS has no data to transmit in the upcoming ON period of the UE, the BS can further save the battery of the UE by transmitting a wake-up signal (WUS) before the start of the ON period of the UE to inform the UE that there is no need to wake up in the ON period (i.e., there is no need to start the onDuration timer). Here, for the UE among the UEs configured with C-DRX and that there is no data to transmit / receive in the upcoming ON period, the BS can transmit a WUS that can be transmitted via DCI format 2_6, which is used to notify power saving information outside the DRX active time for one or more UEs, at a WUS occasion configured before the ON period, to indicate to the UE that there is no need to wake up in the current ON period. A UE that receives the above WUS (e.g., wake-up indication via DCI format 2_6) can save more energy because it can continue to sleep without switching to active mode.

[0198] In the following description, UE DRX or C-DRX, I-DRX may mean discontinuous reception from the UE's perspective, cell DRX may mean discontinuous reception from the BS's perspective, and cell DTX may mean discontinuous transmission from the BS's perspective. Cell DRX may mean UL transmission OFF from the UE's perspective, and cell DTX may mean DL reception OFF from the UE's perspective.

[0199] Cell DTX / DRX configuration can include parameters such as periodicity, slot / offset, and On period similar to the C-DRX configuration of the UE. Cell DTX configuration and cell DRX configuration can be independently configured and activated / deactivated to operate. That is, cell DTX can be configured and activated without cell DRX configuration to perform cell DTX operation, or conversely, cell DRX can be configured without cell DTX configuration to perform cell DRX operation. Even if both cell DTX and cell DRX are configured, only one of the two settings can be activated and operate. According to the cell DTX / DRX operation, as in a structure similar to the C-DRX of the UE, an active period (also called an ON period) can be set in which all signals and channels can be transmitted / received without restriction, and a non-active period, which is a time period outside the active period in which transmission / reception of all signals and channels is OFF or transmission / reception of only specific signals and channels is performed in a restricted manner (e.g., only transmission / reception of channels / signals such as PDCCH transmission or RACH / SR PUCCH reception is allowed). The cell DTX / DRX configuration can be set and activated only by RRC (i.e., only through RRC signaling), or all or part of the parameters for the cell DTX / DRX can be set by RRC and activated through L1 signaling such as PDCCH or DCI (e.g., (group-common) DCI). During the active period of cell DTX / DRX, transmission / reception of all signals and channels is possible without any special transmission / reception restrictions, just like normal operation of BS.The time interval outside the active interval is basically considered as a non-active interval, and transmission / reception may be restricted except for the preset signal(s) and channel(s), and since the BS can obtain ES gain through the operation of performing only this minimum transmission / reception, the operation when the NES state / mode is ON may be considered in the time interval outside the active interval.

[0200] For example, to reduce the BS downlink transmission / uplink reception active time, the UE can be configured with a periodic cell DTX / DRX pattern (i.e., active and non-active periods). The pattern configuration for cell DTX / DRX can be common to the UEs in the cell. Each serving cell can be configured with a periodic cell DTX pattern by RRC. The BS can configure only cell DTX, only cell DRX, or both for a cell. Cell DTX and cell DRX patterns can be configured and activated separately. Up to N cell DTX / DRX patterns per MAC entity can be configured for different serving cells, where N can be a predefined value. Cell DTX / DRX can be activated / deactivated by RRC signaling or L1 group common signaling (e.g., signaling via group-common PDCCH). The BS can control the cell DTX and cell DRX operation by providing the cell DTX / DRX configuration via RRC signaling. For example, the BS can provide RRC parameters in the cell DTX / DRX configuration regarding a timer for an active period at the beginning of a cell DTX / DRX cycle (e.g., a cell DTX / DRX ON duration timer), a subframe in which the cell DTX / DRX cycle starts, a delay before the active period starts, a cell DTX / DRX cycle period (i.e., a cell DTX / DRX cycle), etc. The active duration of the cell DTX / DRX can be a period of time during which the UE waits to receive PDCCHs or SPS occasions and to transmit an SR or CG. A cycle of the cell DTX / DRX specifies a periodic repetition of an active period followed by an inactive period. The active duration and cycle parameters can be common between the cell DTX and the cell DRX.The BS may configure the C-DRX and the cell DTX / DRX such that there is at least a partial overlap between the C-DRX ON period of the UE and the cell DTX / DRX active period. For example, the BS may configure the C-DRX periodicity of the UE to be an integer multiple of the cell DTX / DRX periodicity, or the cell DTX / DRX periodicity to be an integer multiple of the C-DRX periodicity of the UE.

[0201] In some implementations, cell DTX operation may affect the UE's monitoring activity for PDCCH and configured downlink assignments in RRC_CONNECTED. For a serving cell for which cell DTX is configured and active, a UE (e.g., the MAC entity of the UE) monitors PDCCH on the serving cell if the serving cell is within the cell DTX active period. The cell DTX active period of a serving cell may include the time that a cell DTX / DRX ON duration timer runs for the serving cell. For example, for a serving cell for which cell DTX is configured and active, a UE (e.g., the MAC entity of the UE) may not monitor PDCCH on the serving cell if the serving cell is not within the cell DTX active period or is within the UE C-DRX active period, and may not receive transport blocks on the serving cell according to the configured downlink assignment for SPS (i.e., perform SPS PDSCH reception). That is, when cell DTX is set and activated for a serving cell, the UE may not perform PDCCH monitoring on the serving cell or monitor SPS periods on the serving cell during the cell DTX inactivity period.

[0202] In some implementations, cell DRX operation may control SR and configured uplink grant transmission activity in RRC_CONNECTED. In some scenarios, when cell DRX is configured and activated for a serving cell, the UE (e.g., the MAC entity of the UE) may, in principle, perform CG PUSCH transmissions and (if the serving cell is a PUCCH cell) PUCCH transmissions on the serving cell only within the cell DRX active period. The cell DTX active period of a serving cell may include the time that the cell DTX / DRX ON duration timer runs for the serving cell. For example, if a serving cell for which cell DRX is configured and activated is within a cell DRX inactive period, the UE (e.g., the MAC entity of the UE) does not transmit SR on PUCCH resources for SR (even if the serving cell is a PUCCH cell), does not report periodic CSI on PUCCH (even if the serving cell is a PUCCH cell), and does not report semi-persistent CSI configured on PUSCH of the serving cell. In other words, if cell DRX is configured and activated for a serving cell, the UE may not transmit on CG resources of the serving cell or may not transmit SR on the serving cell during the DRX inactive period.

[0203] Meanwhile, in addition to the cell DTX / DRX configuration where a specific ON / OFF duration pattern is periodically repeated in advance, the BS may perform cell OFF to completely turn off a specific cell for a certain period of time to save more energy. When a cell is turned OFF, the UEs in that cell cannot transmit / receive data at all and may need to move to another turned-on cell. In particular, if the target cell for cell OFF is the PCell of specific UEs, it may be necessary to trigger a handover process for the UE to change the PCell.

[0204] Handover is a procedure to ensure seamless connectivity when a UE moves within a network. Typically, a UE performs measurements on neighboring cells and reports these to the network, which then determines whether the UE should be handed over. Unlike a typical handover, where a handover is executed by the UE when the network issues a handover command, a conditional handover (CHO) is a handover executed by the UE when one or more handover execution conditions are met. CHO refers to a process in which a UE performs / triggers a handover process on its own when a pre-defined condition is met, even if the BS does not directly issue a handover command. A UE configured with a CHO by a BS in a source cell evaluates whether one or more handover conditions (e.g., RSRP / RSRQ of a reference signal, SINR, etc.) are met, and if the conditions are met, it performs a handover process by transmitting an RACH to the target cell. When a CHO configuration is present, a UE starts evaluating CHO execution conditions, and may continuously perform the evaluation of CHO execution conditions until it receives a handover command from a BS to perform a handover or until it performs a handover to a candidate cell that satisfies the CHO execution conditions. That is, when a CHO configuration is present, the UE may have to continue to perform measurements for evaluating CHO execution conditions, which may unnecessarily consume power, even in situations where RRC re-establishment is not required. On the other hand, when a CHO configuration is present for a UE and a cell DTX / DRX configuration exists for the serving cell of the UE, there is a possibility that the CHO execution conditions may be determined to be satisfied due to an inactive period of the cell DTX / DRX, which may result in an unnecessary handover. In consideration of this, in some implementations of the present specification described below, a BS may dynamically instruct the UE to trigger a CHO process (e.g., to use a CHO execution condition).For example, the handover process trigger can be dynamically indicated via L1 (UE-specific or group-common) signaling.

[0205] A UE may be configured with cell DTX configuration and / or cell DRX configuration for a serving cell, and activation or deactivation of the configured cell DTX / DRX configuration may be performed via higher layer signaling such as an RRC signal, and may also receive an activation / deactivation instruction dynamically in a group-common manner via a specific DCI format (e.g., DCI format 2_9). DCI format 2_9 may be used for multiple UEs. Additionally, each UE may have one or multiple serving cells. For example, DCI format 2_9 may be configured with multiple information blocks for each of the serving cell(s) of the multiple UEs, and each information block may be configured to include at least one bit for activation or deactivation of the configured cell DTX configuration and / or one bit for activation or deactivation of the configured cell DRX configuration for the corresponding serving cell. When a UE is configured to monitor DCI format 2_9 in a Type-3 common search space, the position of the information block that it must monitor within DCI format 2_9 can be set in advance as an RRC parameter (hereinafter, position-inDCI-NES).

[0206] Each information block of DCI format 2_9 may have different bit widths depending on whether cell DTX / DRX is configured. For example, for a serving cell with only cell DTX or cell DRX configured, the corresponding information block may consist of 1 bit, and the 1 bit may indicate activation or deactivation of cell DTX or cell DRX for the serving cell, depending on whether its value is 0 or 1. As another example, for a serving cell with both cell DTX and cell DRX configured, the corresponding information block may consist of 2 bits, and the first bit of the 2 bits may indicate activation or deactivation of cell DTX operation, and the second bit may indicate activation or deactivation of cell DRX operation. In some implementations of the present specification, DCI format 2_9 may be used to provide cell OFF mode indication (e.g., NES mode indication) of the primary cell(s) to one or more UEs. For example, a CHO triggering bit for cell OFF can be added to an information block for a specific serving cell (e.g., PCell) among the information blocks in DCI format 2_9. In this case, the information block corresponding to the serving cell can be composed of 1 bit, 2 bits, or n bits depending on whether the cell DTX / DRX is configured.

[0207] Hereinafter, when a BS operates in a network energy saving (NES) mode for energy saving (ES), it can mean, for example, that the BS sets multiple OFF intervals (i.e., discontinuous transmixxion (DTX) intervals of the BS) in advance to turn off transmission of a specific DL signal during a specific time interval, and dynamically indicates one of the OFF intervals to indicate that the corresponding DL signal will not be transmitted during the predefined time interval, thereby achieving power consumption savings of the BS and UE. Hereinafter, the NES mode can also mean an operation mode in which power consumption savings of the BS and UE are achieved not only in the domain but also in the frequency domain, such as BWP switching, dynamic resource block (RB) adaptation, etc., and in the spatial domain, for example, when a specific receive antenna port of the BS is turned off semi-statically or dynamically, by the BS not performing transmission and / or reception through the corresponding antenna port.

[0208] The BS can apply technologies such as controlling the on / off period in the time domain for NES purposes, controlling the transmission / reception resources for UE-common or UE-specific signals / channels, changing the amount of frequency domain resources, controlling the transmission power, or turning on / off antenna port(s) or TRP(s) in the spatial domain. The state in which such technologies(s) (hereinafter, referred to as NES_tech for convenience) are applied is referred to as NES mode or NES state. The BS can notify the UE of which NES_tech(s) are applied for each NES_tech (or its group) (hereinafter, Approach 1), or can pre-configure the corresponding NES_tech (or its group)(s) for each code-point of a specific indicator (the indicator can be provided by DCI or MAC CE, etc., or can be configured by upper layer signaling) (hereinafter, Approach 2). For Approach 1, if at least one NES_tech is applied, the state can be expressed as a NES mode or NES state, or can be called a different NES mode or different NES state depending on which NES_tech is applied. For Approach 2, for example, when there is a 1-bit indicator, a value of '0' can represent that there is no corresponding NES_tech, and a value of '1' can be associated with one or more NES_tech. For Approach 2, if the indicator has a value of '0', the UE can assume that the BS (or cell) is not in a NES state / mode, and if the indicator has a value of '1', the UE can assume that the BS (or cell) is in a NES mode / state where one or more NES_techs are applied.As another example, when there is a 2-bit indicator, if the value '00' means that there is no corresponding NES_tech, the value '01' means that one or more NES_tech_As are engaged, the value '10' means that one or more NES_tech_Bs are engaged, and the value '11' means that one or more NES_tech_Cs are engaged, then the UE can assume that the state is NES mode or NES state if it obtains a code-point other than the value '00' from the indicator, and can determine / assume that obtaining the value '01' means NES state #1, obtaining the value '10' means NES state #2, and obtaining the value '11' means NES state #3. In other words, it may be possible to distinguish whether it is an NES state or not or which NES state it is based on the code-point.

[0209] In light-load situations with little data to transmit, a BS can save energy by turning off transmission / reception of specific DL / UL signals and channels for a certain period of time, or by reducing the amount of frequency resources such as BWPs it operates. However, since transmission of common signals / channels such as SSB / SIB1 / Type#0 CSS is essential for cell (re)selection, initial access, and RRM measurements, the BS may transmit the corresponding signals / channels at each transmission period(s) regardless of the power saving mode operation. If the BS does not transmit these signals at all or transmits them at too long a period, problems may occur in cell detection, time and frequency synchronization of the UE, and thus the performance of the UEs connected to the corresponding cell may deteriorate.

[0210] However, a BS operating multiple frequency bands may consume a large amount of energy by periodically sending SSB and / or system information, even when the number of UEs served is small or the traffic load is relatively low.

[0211] Figure 14 illustrates an example of SSB transmission by a BS operating multiple frequency bands.

[0212] Referring to FIG. 14, a BS operating in three frequency bands can save energy by periodically transmitting (legacy) SSB only in some frequency bands (e.g., F1), transmitting simplified (or modified) SSB (hereinafter, S-SSB) in the remaining frequency bands (e.g., F2), or not transmitting SSB in other frequency bands (e.g., F3). For example, in some implementations, S-SSB may consist only of PSS and SSS. Referring to FIG. 14, in some implementations of the present specification, a UE operating in F2 or F3 may request SSB transmission from a BS in the corresponding frequency band. Hereinafter, an SSB transmitted upon request by a UE is referred to as an on-demand SSB for convenience. In some implementations, the on-demand SSB may be a legacy SSB. Alternatively, in some implementations, the on-demand SSB may be an S-SSB. Here, a cell in which legacy SSB may not be transmitted, such as F2 or F3 in FIG. 14, may be conveniently named an SSB-less cell, and from the UE's perspective, an SSB-less cell may be a PCell, a PSCell, and / or an SCell.

[0213] In this specification, frequency band may be replaced with band, carrier, serving cell, BWP, etc., and some implementations of this specification may be applied.

[0214] According to some implementations of this specification, the BS may save time-domain BS energy by reducing transmission of common signals / channels such as SSB / SIB1 / other SI / paging, etc. or adjusting transmission cycles.

[0215] <Method #1> How the BS signals whether to initiate SSB transmission after the UE requests on-demand SSB.

[0216] A UE can be pre-configured by a BS to use specific UL signals / channels (e.g., PRACH, SR PUCCH / PRACH, SRS, PUCCH, and / or PUSCH) for on-demand SSB requests. For convenience, the UL signals / channels for on-demand SSB requests are referred to as OD_SSBs. A UE can be configured with one or more OD_SSBs, and can select different OD_SSB resources according to pre-configured conditions (e.g., SSB index (group) / pattern). In this case, different OD_SSB resources may mean different time / frequency / sequence resources for the same OD_SSB, different types of signals / channels, or different cells corresponding to the OD_SSB resources.

[0217] When a UE requests on-demand SSB through a specific OD_SSB resource, the BS may need to signal whether the request has been properly received and whether the requested SSB transmission will actually be initiated. If the UE always expects SSB reception without separate signaling after transmitting the OD_SSB, a mismatch between the BS and the UE regarding whether SSB transmission is possible may occur, resulting in unnecessary power consumption and inaccurate judgment by the UE.

[0218] Therefore, in some implementations of this specification, the BS may indicate to the UE (by SSB index (group)) whether to initiate SSB transmission after receiving an on-demand SSB request via a specific signal (e.g., group-common DCI, UE-specific DCI, or (group-common) MAC CE). The UE may obtain information about the SSB index it requested and transmission information about other SSB indices (if any) via the indication. Furthermore, the UE may not unconditionally assume SSB reception when it requests SSB transmission from the BS via OD_SSB, but may perform SSB (reception) operation on the corresponding band or cell based on information received via the specific signal (e.g., information about whether actual SSB transmission is initiated).

[0219] When the BS indicates whether to transmit SSB in the form of group-common (GC) DCI, the SSB transmission-related information may be configured in a format similar to DCI format 2_9 for cell DTX / DRX activation (release). For example, a plurality of information blocks corresponding to each of a plurality of serving cells may be configured in the DCI format, the position(s) of the information block(s) to be monitored for each UE may be set, and the initiation of SSB transmission for a specific serving cell may be instructed to the plurality of UEs through the DCI format. Alternatively, a form in which the SSB transmission-related information is jointly indicated by an existing GC DCI (e.g., DCI format 2_X series) such as DCI format 2_9 may also be considered. For example, an N-bit for indicating whether to initiate on-demand SSB transmission may be added separately from the cell DTX / DRX activation (release) indication for each information block corresponding to a specific serving cell in DCI format 2_9. For example, if the number of candidate SSBs for a serving cell (e.g., candidate SSB indices of SSBs actually transmitted on the serving cell) is M, N=M bits corresponding to the SSB candidates (respectively) may be included. In addition, if whether or not to transmit SSB is indicated through UE-specific DCI or (group-common) MAC CE, a bit indicating whether or not to transmit SSB may be added to a specific DCI format, or an index and a logical channel identifier (LCID) indicating whether or not to transmit SSB may be added within the MAC CE.

[0220] Meanwhile, if the activation (release) indication of on-demand SSB can be signaled in the form of a specific signal (e.g., group-common DCI, UE-specific DCI or (group-common) MAC CE), in some implementations of the present specification, the time period during which the corresponding SSB is transmitted may be between the time when the activation indication is received by the UE and the time before the deactivation indication is received, depending on the signaling (e.g., the activation (release) indication of on-demand SSB). Alternatively, the UE and / or the BS may consider the on-demand SSB transmission to be deactivated after a certain period of time (e.g., when the timer expires) (via a pre-configured timer / duration) after receiving / transmitting the activation indication. In this case, the timer / duration may be configured in advance by a higher layer signal such as an RRC signal, or may be directly indicated (one of multiple pre-defined candidate timer / duration values) via GC DCI.

[0221] In some implementations of this specification, the actual SSB reception time by the UE after receiving a specific signal (e.g., group-common DCI, UE-specific DCI or (group-common) MAC CE) may be set to a certain application delay from the time the UE transmits the OD_SSB signal or from the time the specific signal (e.g., group-common DCI, UE-specific DCI or (group-common) MAC CE) is received, taking into account processing time such as the time it takes for the UE to decode the GC DCI and prepare for SSB reception operation. For example, the application delay may be defined in a form similar to the application of DCI format 2_9. The following table illustrates application delays for cell DTX / DRX configuration. When a UE receives DCI format 2_9 in slot n, it may not be able to apply a pre-configured cell DTX / DRX active / non-active pattern in slot n or the immediately following slot, slot n+1, but may require a minimum of the following delay, including processing time, depending on the subcarrier spacing (SCS) of the PDCCH carrying DCI format 2_9.

[0222]

[0223] The UE may apply the actual cell DTX or DRX activation / deactivation change (e.g., from activated to deactivated or vice versa) from the start of slot X, which may mean the first slot not earlier than (e.g., equal to or immediately after) slot n plus the delay value from slot n in which DCI format 2_9 is received. In some implementations of this specification, a SCS-based application delay may be similarly defined from the time point at which the OD_SSB signal is transmitted.

[0224] Meanwhile, in some implementations, on-demand SSB may be operated to save energy of the SCell. For example, when the SCell is activated, SSB transmission may be turned ON and operating, and then turned OFF midway through a timer / period or GC DCI. Or, as another example, SSB transmission may be OFF when the SCell is activated and then turned ON later through GC DCI, the activation MAC CE and / or GC DCI may include ON / OFF information by SSB index (group). For example, the GC DCI that indicates whether SSB transmission is enabled (e.g., SSB transmission is activated) may include ON / OFF information by SSB index (group) and which SCell (group) the SSB ON / OFF information corresponds to.

[0225] In some implementations, it may also be considered to link the center frequency location of the SSB with a specific bit position within the GC DCI indicating on-demand SSB activation (deactivation). For example, when UEs with different PCells are present on the same SCell, SSBs may be transmitted at different center frequencies.

[0226] Meanwhile, when an on-demand SSB configuration is provided for a specific serving cell, multiple on-demand SSB configurations may be provided. For example, one or more OD-SSB configuration sets, each including on-demand SSB parameter(s), may be configured, and each OD-SSB configuration set may be assigned an index, and the index value may be signaled via the aforementioned GC DCI and / or MAC CE. In this case, the on-demand SSB parameter(s) may include at least one of the following parameters.

[0227] > Frequency resource information (e.g. center frequency, subcarrier spacing) on ​​which on-demand SSB is transmitted.

[0228] > Candidate SSB index or SSB transmission position transmitted within an SSB burst, similar to the existing ssb-PositionsInBurst parameter.

[0229] > When on-demand SSB will be transmitted (e.g., parameter for the interval between slot n where GC-DCI / MAC-CE is received and the first on-demand SSB)

[0230] > Number of transmissions and / or transmission duration / window since on-demand SSB transmission began

[0231] > Cycle of on-demand SSB

[0232] > Half-frame index where on-demand SSB is transmitted

[0233] > Information on the transmission power values ​​of on-demand SSB

[0234] When the SSB index (group) of the on-demand SSB(s) to be turned ON of the SCell(s) is transmitted through the aforementioned GC DCI and / or MAC CE, multiple on-demand SSB configuration set candidates may be preset for each SCell through a higher layer signal such as an RRC signal, and one of the configuration set candidates may be dynamically indicated for each SCell through the GC DCI and / or MAC CE.

[0235] For example, if OD-SSB configuration sets #1 to #4 are configured in advance for a specific serving cell, N bits (e.g., N=2) may be allocated in the GC DCI and / or MAC CE to indicate whether to initiate on-demand SSB transmission for the serving cell. If '01' is indicated in the corresponding N bit information, the UE may receive on-demand SSB corresponding to OD-SSB configuration set #2 in the corresponding serving cell.

[0236] <Method #2> On-demand SSB transmission method when cell DTX / DRX is configured and activated

[0237] When cell DTX / DRX is configured and activated for a specific serving cell, a cell DTX / DRX pattern in which active and inactive periods are periodically repeated is applied to the serving cell, so that transmission of specific DL signals / channels (including SSB) that have been promised / configured in advance can be turned OFF during the cell DTX inactive period. Reception of UL signals / channels that have been promised / configured in advance can be turned OFF during the cell DRX inactive period. For example, BS does not transmit signals / channels that have been promised / configured to be OFF during the cell DTX inactive period, and UE does not expect reception of such signals / channels.

[0238] Therefore, when cell DTX / DRX is configured and activated for a specific cell, consideration may need to be given to whether to allow SSB or on-demand SSB transmission in the cell DTX / DRX inactive period and whether to allow SSB transmission requests via OD_SSB.

[0239] A BS may configure and activate cell DTX for specific serving cell(s) for the purpose of energy saving. Whether (on-demand) SSB is ON or OFF in the non-active period of the cell DTX may be defined as configurable or defined in the specification. For example, if on-demand SSB is set to ON in the non-active period or defined in the specification, the UE may transmit OD_SSB in the cell DTX non-active period and expect SSB reception. In another example, if on-demand SSB is set to OFF in the non-active period of the cell DTX or defined in the specification, since SSB reception cannot be expected within the non-active period, when an OB-SSB signal is transmitted, the OD_SSB signal itself may not be transmitted.

[0240] In some implementations, it is also possible to always have the (on-demand) SSB ON during the inactive period, but with the SSB transmission period configured (or defined in the specification) differently for the Cell DTX inactive period and the Cell DTX active period. For example, the SSB transmission period may be configured / defined to be relatively longer during the Cell DTX inactive period compared to the active period.

[0241] In some implementations, whether to allow transmission of an OD_SSB signal requesting on-demand SSB of a UE in a cell DRX non-active period may also be configurable or defined in the specification. Alternatively, transmission of OD_SSB in a cell DRX non-active period may always be allowed, but the transmittable cycle of the corresponding on-demand signal (e.g., OD_SSB signal) may be configured (or defined in the specification) differently for the cell DRX non-active period and the cell DRX active period. For example, the UE may be configured / defined to have a longer OD_SSB cycle for the cell DRX non-active period than for the cell DRX active period.

[0242] According to some implementations of this specification, a BS can save energy by transmitting SSBs with relatively long periods or by not transmitting SSBs until requested by a UE. According to some implementations of this specification, when short-period SSB transmission is required, a UE can transmit an SSB transmission request, and when the BS receives the SSB transmission request, it notifies all UEs in the cell that the SSB transmission request has been successfully received and which SSB will be transmitted, thereby obtaining energy saving benefits while minimizing performance degradation of the UE.

[0243] Figure 15 illustrates the flow of DL signal reception in a UE according to some implementations of the present specification.

[0244] A UE may perform operations according to some implementations of the present disclosure in connection with receiving a DL signal. The UE may include at least one transceiver; at least one processor; and at least one computer memory operably connected to the at least one processor and storing instructions that, when executed, cause the at least one processor to perform operations according to some implementations of the present disclosure. A processing device for the UE may include at least one processor; and at least one computer memory operably connected to the at least one processor and storing instructions that, when executed, cause the at least one processor to perform operations according to some implementations of the present disclosure. A computer-readable (non-volatile) storage medium may store at least one computer program comprising instructions that, when executed by at least one processor, cause the at least one processor to perform operations according to some implementations of the present disclosure. A computer program or computer program product may be recorded on at least one computer-readable (non-volatile) storage medium and may contain instructions that, when executed, cause (at least one processor) to perform operations according to some implementations of the present specification.

[0245] Referring to FIG. 15, in a method performed by the UE, or in the UE, the processing device, the computer-readable (non-volatile) storage medium, and / or the computer program product, the operations may include: receiving an on-demand SSB related configuration (S1501). For example, the method or the operations may: receive a radio resource control (RRC) configuration, wherein the RRC configuration may include a configuration regarding a start bit position of a specific downlink control information format for each of one or more information blocks respectively associated with one or more cells. The method or the operations may: transmit an SSB transmission request (1503). For example, the method or the operations may: transmit a request for transmission of a first synchronization signal for a first cell among the one or more cells. The method or the operations may: perform downlink control channel monitoring for receiving SSB activation (release) information (e.g., the specific downlink control information format) after transmitting the SSB transmission request. The method or the operations may: obtain a first information block for the first cell from among the one or more information blocks in the specific downlink control information format based on detection (S1505) of the specific downlink control information format; and determine whether the first synchronization signal is activated based on the first information block. The method or the operations may include: starting monitoring of the first synchronization signal on the first cell based on the first synchronization signal being activated.

[0246] In some implementations, the first information block may include bits indicating which of the synchronization signal candidates for the first cell are to be activated for transmission.

[0247] In some implementations, monitoring of the first synchronization signal may be discontinued based on the user device receiving a deactivation instruction for the first synchronization signal.

[0248] In some implementations, monitoring of the first synchronization signal may begin at least after a predetermined application delay after the particular downlink control information format is detected.

[0249] In some implementations, the method or the operations may: receive a plurality of on-demand synchronization signal configuration sets for the first cell. Each of the plurality of on-demand synchronization signal configuration sets may include at least one of: i) frequency resource information for the on-demand synchronization signals, ii) time resource information for the on-demand synchronization signals, iii) candidate synchronization signal indices, iv) transmission windows for the on-demand synchronization signals, v) periods of the on-demand synchronization signals, vi) half-frame indices for the on-demand synchronization signals, or vii) transmission power related information for the on-demand synchronization signals.

[0250] In some implementations, the method or the operations may include: receiving a cell discontinuous transmission (DTX) configuration for the first cell.

[0251] In some implementations, the cell DTX setting may include information regarding whether a synchronization signal transmission request for the first cell is allowed.

[0252] In some implementations, monitoring of the first synchronization signal may be performed at different intervals during active and non-active periods based on the cell DTX settings.

[0253] Figure 16 illustrates the flow of DL signal transmission in BS according to some implementations of the present specification.

[0254] A BS may perform operations according to some implementations of the present disclosure in connection with DL signal transmission. The BS may include at least one transceiver; at least one processor; and at least one computer memory operably connected to the at least one processor and storing instructions that, when executed, cause the at least one processor to perform operations according to some implementations of the present disclosure. A processing device for the BS may include at least one processor; and at least one computer memory operably connected to the at least one processor and storing instructions that, when executed, cause the at least one processor to perform operations according to some implementations of the present disclosure. A computer-readable (non-volatile) storage medium may store at least one computer program comprising instructions that, when executed by the at least one processor, cause the at least one processor to perform operations according to some implementations of the present disclosure. A computer program or computer program product may be recorded on at least one computer-readable (non-volatile) storage medium and may contain instructions that, when executed, cause (at least one processor) to perform operations according to some implementations of the present specification.

[0255] Referring to FIG. 16, in a method performed by the BS, or in the BS, the processing device, the computer-readable (non-volatile) storage medium, and / or the computer program product, the operations may include: transmitting on-demand SSB related settings (S1601). For example, the method or the operations may: transmit radio resource control (RRC) settings, wherein the RRC settings may include settings regarding a start bit position of a specific downlink control information format for each of one or more information blocks respectively associated with one or more cells. The method or the operations may: receive an SSB transmission request (1603). For example, the method or the operations may: receive a request for transmitting a first synchronization signal for a first cell among the one or more cells. The method or the operations may: transmit a downlink control channel for transmission (S1605) of SSB activation (release) information (e.g., the specific downlink control information format or MAC CE) after receiving the SSB transmission request. The SSB activation (release) information may include information on whether the first synchronization signal is activated in a first information block for the first cell among the one or more information blocks. The method or the operations may include: starting transmission of the first synchronization signal on the first cell based on the first synchronization signal being activated.

[0256] In some implementations, the first information block may include bits indicating which of the synchronization signal candidates for the first cell are to be activated for transmission.

[0257] In some implementations, transmission of the first synchronization signal may be discontinued based on the base station transmitting a deactivation indication for the first synchronization signal.

[0258] In some implementations, transmission of the first synchronization signal may begin at least after a predetermined applied delay after the downlink channel carrying the particular downlink control information format is transmitted.

[0259] In some implementations, the method or the operations may include transmitting a plurality of on-demand synchronization signal configuration sets for the first cell. Each of the plurality of on-demand synchronization signal configuration sets may include at least one of: i) frequency resource information for the on-demand synchronization signals, ii) time resource information for the on-demand synchronization signals, iii) candidate synchronization signal indices, iv) a transmission window for the on-demand synchronization signals, v) a period of the on-demand synchronization signals, vi) a half-frame index for the on-demand synchronization signals, or vii) transmission power related information for the on-demand synchronization signals.

[0260] In some implementations, the method or the operations may include: transmitting a cell discontinuous transmission (DTX) configuration for the first cell.

[0261] In some implementations, the cell DTX setting may include information regarding whether a synchronization signal transmission request for the first cell is allowed.

[0262] In some implementations, transmission of the first synchronization signal may be performed at different intervals in active and non-active periods based on the cell DTX settings.

[0263] As described above, the examples disclosed herein are provided to enable those skilled in the art to implement and practice the present disclosure. While the examples have been described above with reference to the examples of the present disclosure, those skilled in the art will appreciate that various modifications and variations may be made to the examples of the present disclosure. Accordingly, the present disclosure is not intended to be limited to the examples described herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

[0264] Implementations of this specification can be used in wireless communication systems, BSs, user equipment, and other equipment.

Claims

Receive a radio resource control (RRC) configuration, wherein the RRC configuration includes a configuration regarding a start bit position of a specific downlink control information format for a first information block associated with a first cell; Transmitting a request for transmission of a first synchronization signal to the first cell; Perform downlink channel monitoring carrying the above specific downlink control information format; Based on detection of the specific downlink control information format, obtaining the first information block for the first cell within the specific downlink control information format; Based on the first information block, determining whether the first synchronization signal is activated; and Including starting monitoring of the first synchronization signal on the first cell based on the activation of the first synchronization signal; Method by user device. In the first paragraph, The first information block includes bits that indicate which of the synchronization signal candidates for the first cell are to be activated for transmission. Method by user device. In the first paragraph, The monitoring of the first synchronization signal is stopped based on the user device receiving a deactivation instruction for the first synchronization signal. Method by user device. In the first paragraph, The monitoring of the above first synchronization signal starts at least after a predetermined application delay after the specific downlink control information format is detected. Method by user device. In the first paragraph, Receive a plurality of on-demand synchronization signal configuration sets for the first cell, each of the plurality of on-demand synchronization signal configuration sets including at least one of: i) frequency resource information for the on-demand synchronization signals, ii) time resource information for the on-demand synchronization signals, iii) candidate synchronization signal indices, iv) transmission windows for the on-demand synchronization signals, v) periods of the on-demand synchronization signals, vi) half-frame indices for the on-demand synchronization signals, or vii) transmission power related information of the on-demand synchronization signals. Method by user device. In the first paragraph, Including receiving a cell discontinuous transmission (DTX) setting for the first cell, The above cell DTX setting includes information on whether a request for synchronization signal transmission for the first cell is allowed. Method by user device. In the first paragraph, Including receiving a cell discontinuous transmission (DTX) setting for the first cell, The monitoring of the above first synchronization signal is performed at different intervals in the active and non-active periods based on the cell DTX settings. Method by user device. At least one transceiver; at least one processor; and At least one computer memory operably connected to said at least one processor and storing instructions that, when executed, cause said at least one processor to perform operations, said operations comprising: Receive a radio resource control (RRC) configuration, wherein the RRC configuration includes a configuration regarding a start bit position of a specific downlink control information format for a first information block associated with a first cell; Transmitting a request for transmission of a first synchronization signal to the first cell; Perform downlink channel monitoring carrying the above specific downlink control information format; Based on detection of the specific downlink control information format, obtaining the first information block for the first cell within the specific downlink control information format; Based on the first information block, determining whether the first synchronization signal is activated; and Including starting monitoring of the first synchronization signal on the first cell based on the activation of the first synchronization signal; Method by user device. User device. In a processing device in a wireless communication system, at least one processor; and At least one computer memory operably connected to said at least one processor and storing instructions that, when executed, cause said at least one processor to perform operations, said operations comprising: Receive a radio resource control (RRC) configuration, wherein the RRC configuration includes a configuration regarding a start bit position of a specific downlink control information format for a first information block associated with a first cell; Transmitting a request for transmission of a first synchronization signal to the first cell; Perform downlink channel monitoring carrying the above specific downlink control information format; Based on detection of the specific downlink control information format, obtaining the first information block for the first cell within the specific downlink control information format; Based on the first information block, determining whether the first synchronization signal is activated; and Including starting monitoring of the first synchronization signal on the first cell based on the activation of the first synchronization signal; Processing unit. In a computer-readable storage medium, The storage medium stores at least one program code including instructions that, when executed, cause at least one processor to perform operations, the operations comprising: Receive a radio resource control (RRC) configuration, wherein the RRC configuration includes a configuration regarding a start bit position of a specific downlink control information format for a first information block associated with a first cell; Transmitting a request for transmission of a first synchronization signal to the first cell; Perform downlink channel monitoring carrying the above specific downlink control information format; Based on detection of the specific downlink control information format, obtaining the first information block for the first cell within the specific downlink control information format; Based on the first information block, determining whether the first synchronization signal is activated; and Including starting monitoring of the first synchronization signal on the first cell based on the activation of the first synchronization signal; Storage medium. Transmitting a radio resource control (RRC) configuration, wherein the RRC configuration includes a configuration regarding a start bit position of a specific downlink control information format for a first information block associated with a first cell; Receive a request for transmission of a first synchronization signal for the first cell; Transmitting a downlink channel carrying the specific downlink control information format, wherein the first information block for the first cell in the specific downlink control information format includes information about whether the first synchronization signal is activated; and Including starting transmission of the first synchronization signal on the first cell based on the activation of the first synchronization signal. Method by base station. At least one transceiver; at least one processor; and At least one computer memory operably connected to said at least one processor and storing instructions that, when executed, cause said at least one processor to perform operations, said operations comprising: Transmitting a radio resource control (RRC) configuration, wherein the RRC configuration includes a configuration regarding a start bit position of a specific downlink control information format for a first information block associated with a first cell; Receive a request for transmission of a first synchronization signal for the first cell; Transmitting a downlink channel carrying the specific downlink control information format, wherein the first information block for the first cell in the specific downlink control information format includes information about whether the first synchronization signal is activated; and Including starting transmission of the first synchronization signal on the first cell based on the activation of the first synchronization signal. Base station. In Article 12, The first information block includes bits that indicate which of the synchronization signal candidates for the first cell are to be activated for transmission. Base station. In Article 12, The transmission of the first synchronization signal is stopped based on the base station transmitting a deactivation instruction for the first synchronization signal. Base station. In Article 12, The transmission of the first synchronization signal starts at least after a predetermined applied delay after the downlink channel carrying the specific downlink control information format is transmitted. Base station. In Article 12, Transmitting a plurality of on-demand synchronization signal configuration sets for the first cell, each of the plurality of on-demand synchronization signal configuration sets including at least one of: i) frequency resource information for on-demand synchronization signals, ii) time resource information for the on-demand synchronization signals, iii) candidate synchronization signal indices, iv) transmission windows for the on-demand synchronization signals, v) periods of the on-demand synchronization signals, vi) half-frame indices for the on-demand synchronization signals, or vii) transmission power related information of the on-demand synchronization signals. Base station. In Article 12, Including transmitting a cell discontinuous transmission (DTX) setting for the first cell, The above cell DTX setting includes information on whether a request for synchronization signal transmission for the first cell is allowed. Base station. In Article 12, Including transmitting a cell discontinuous transmission (DTX) setting for the first cell, The transmission of the above first synchronization signal is performed at different cycles in the active and non-active periods based on the cell DTX settings. Base station.

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