Method and device for transmitting synchronization signal block and system information for network energy saving

Abstract

A method of a terminal may comprise the steps of: receiving at least one on-demand SSB configuration from a base station through first signaling; receiving an activation indication or a deactivation indication for one or more first SCell(s) from the base station through second signaling; receiving an activation indication or a deactivation indication of on-demand SSB transmission for the one or more first SCell(s) from the base station through third signaling; and when an activation indication of on-demand SSB transmission for one or more second SCell(s) among the one or more first SCell(s) is received through the third signaling, performing SSB reception in the one or more second SCell(s).

Description

Method and device for transmitting synchronization signal blocks and system information for saving network energy

[0001] The present invention relates to energy saving technology for a communication network, and more particularly, to a synchronization signal block for network energy saving (NES) and a method and device for transmitting system information.

[0002] With the advancement of information and communication technology, various wireless communication technologies are being developed. Representative wireless communication technologies include LTE (long term evolution) and NR (new radio), both of which are defined by the 3rd generation partnership project (3GPP) standards. LTE can be one of the 4th generation (4G) wireless communication technologies, and NR can be one of the 5th generation (5G) wireless communication technologies.

[0003] To handle the rapidly increasing amount of wireless data following the commercialization of 4G communication systems (e.g., communication systems supporting LTE), 5G communication systems (e.g., communication systems supporting NR) that use higher frequency bands (e.g., frequency bands higher than 6 GHz) than the frequency bands of 4G communication systems (e.g., frequency bands below 6 GHz) are being considered. 5G communication systems can support enhanced Mobile Broadband (eMBB), Ultra-Reliable and Low Latency Communication (URLLC), and massive Machine Type Communication (mMTC).

[0004] Meanwhile, Network Energy Saving (NES), a technology being standardized by 3GPP, aims to optimize the power consumption of base stations and network elements to improve the energy efficiency of wireless communication networks. NES includes methods to dynamically adjust the activity status of base stations or switch to low-power modes based on traffic load, thereby reducing operating costs for telecommunications operators and supporting the construction of sustainable networks. Meanwhile, NES requires on-demand transmission of synchronization signal blocks (SSBs) and system information. This is necessary because unnecessary SSB and system information broadcasts need to be minimized to conserve network energy. Since existing periodic transmission methods can result in unnecessary signal transmission even under low-load or power-saving conditions, providing SSBs and system information only when necessary, based on terminal requests or network needs, can further improve energy efficiency.

[0005] The purpose of the present invention to solve the above problems is to provide a synchronization signal block for network energy saving (NES) and a method and device for transmitting system information.

[0006] According to one embodiment of the present disclosure for achieving the above object, a method of a terminal may include: receiving at least one on-demand synchronization signal block (SSB) configuration from a base station through a first signaling; receiving an activation instruction or a deactivation instruction for one or more first secondary cell (SCell)(s) from the base station through a second signaling; receiving an activation instruction or a deactivation instruction of on-demand SSB transmission for the one or more first SCell(s) from the base station through a third signaling; and performing SSB reception on one or more second SCell(s) when an activation instruction for on-demand SSB transmission for one or more second SCell(s) among the one or more first SCell(s) is received through the third signaling.

[0007] The above first signaling can use an RRC (radio resource control) message.

[0008] The method may further include a step of receiving configuration information for an existing SSB from the base station.

[0009] If a first part to be included in the at least one on-demand SSB configuration is identical to a second part of the configuration information for the existing SSB, the first part may be omitted from the at least one on-demand SSB configuration.

[0010] If an instruction is received indicating to ignore the configuration information for the above existing SSB, the terminal may not perform SSB reception based on the configuration information for the always transmitted SSB.

[0011] If the at least one on-demand SSB configuration is a plurality of on-demand SSB configurations, each of the plurality of on-demand SSB configurations may include at least one of a frequency at which on-demand SSBs are transmitted, a bitmap indicating the position(s) of SSB(s) actually transmitted within an on-demand SSB burst, a transmission period for the on-demand SSBs, a subcarrier spacing for the on-demand SSBs, a physical cell identifier (PCI) for the on-demand SSBs, a time position for the on-demand SSBs, a transmission power for the on-demand SSBs, or a number of on-demand SSB bursts to be transmitted.

[0012] If the at least one on-demand SSB configuration is one on-demand SSB configuration, the one on-demand SSB configuration may include at least one of one or more frequencies at which on-demand SSBs are transmitted, one or more bitmaps indicating the position(s) of SSB(s) actually transmitted within an on-demand SSB burst, one or more transmission periods for the on-demand SSBs, one or more subcarrier intervals for the on-demand SSBs, one or more PCIs for the on-demand SSBs, a plurality of time positions for the on-demand SSBs, a plurality of transmit powers for the on-demand SSBs, or a number of on-demand SSB bursts to be transmitted.

[0013] The second signaling and the third signaling utilize at least one medium access control (MAC) control element (CE), and the at least one MAC CE may include a first bitmap for indicating activation or deactivation of the one or more first SCell(s) and a second bitmap(s) for indicating activation or deactivation of on-demand SSB transmission for the one or more first SCell(s).

[0014] If the at least one on-demand SSB setting is a plurality of on-demand SSB settings, the second bitmap(s) may be a plurality of bitmaps, and if the at least one on-demand SSB setting is one on-demand SSB setting, the second bitmap(s) may be one bitmap.

[0015] The bits of the first bitmap and the bits of each of the second bitmap(s) may correspond one-to-one.

[0016] The second signaling uses a first MAC CE and the third signaling uses a second MAC CE, wherein the first MAC CE includes a bitmap for an activation indication or a deactivation indication for the one or more first SCell(s), and the second MAC CE may include at least one of information indicating the SCell(s) on which on-demand SSBs are to be transmitted, information indicating one of the at least one on-demand SSB configuration, information indicating a transmission period of on-demand SSBs, or information indicating the number of on-demand SSB bursts to be transmitted.

[0017] The terminal may perform the SSB reception assuming that the on-demand SSB is transmitted starting from the first slot including the SSB actually transmitted within the first SSB burst among the slots after the second time point after the first time point when the first time point related to the third signaling has elapsed.

[0018] When the third signaling uses MAC CE, the first point in time corresponds to slot m in which HARQ (hybrid automatic repeat request)-ACK (acknowledgement) information for the MAC CE is transmitted, the first time is a time corresponding to (the number of slots corresponding to 3 ms + X slots (where X is a natural number greater than or equal to 1)), and the number of slots corresponding to 3 ms is determined based on the subcarrier spacing of the activated uplink bandwidth part (BWP) or the activated downlink BWP, and the second time may correspond to a slot after the first time has elapsed from the slot m.

[0019] According to another embodiment of the present disclosure for achieving the above object, a method of a base station may include: transmitting at least one on-demand synchronization signal block (SSB) configuration to a terminal via a first signaling; transmitting an activation instruction or a deactivation instruction for one or more first secondary cell (SCell)(s) to the terminal via a second signaling; transmitting an activation instruction or a deactivation instruction of on-demand SSB transmission for the one or more first SCell(s) to the terminal via a third signaling; and performing SSB transmission on one or more second SCell(s) when an activation instruction for on-demand SSB transmission for one or more second SCell(s) among the one or more first SCell(s) is transmitted via the third signaling.

[0020] The second signaling and the third signaling utilize at least one medium access control (MAC) control element (CE), and the at least one MAC CE may include a first bitmap for indicating activation or deactivation of the one or more first SCell(s) and a second bitmap(s) for indicating activation or deactivation of on-demand SSB transmission for the one or more first SCell(s).

[0021] If the at least one on-demand SSB setting is a plurality of on-demand SSB settings, the second bitmap(s) may be a plurality of bitmaps, and if the at least one on-demand SSB setting is one on-demand SSB setting, the second bitmap(s) may be one bitmap.

[0022] The bits of the first bitmap and the bits of each of the second bitmap(s) may correspond one-to-one.

[0023] The second signaling uses a first MAC CE and the third signaling uses a second MAC CE, wherein the first MAC CE includes a bitmap for an activation indication or a deactivation indication for the one or more first SCell(s), and the second MAC CE may include at least one of information indicating the SCell(s) on which on-demand SSBs are to be transmitted, information indicating one of the at least one on-demand SSB configuration, information indicating a transmission period of on-demand SSBs, or information indicating the number of on-demand SSB bursts to be transmitted.

[0024] According to another embodiment of the present disclosure for achieving the above object, a terminal may include at least one processor, and the at least one processor may be configured to perform the steps of: receiving at least one on-demand synchronization signal block (SSB) configuration from a base station via a first signaling; receiving an activation instruction or a deactivation instruction for one or more first secondary cell (SCell)(s) from the base station via a second signaling; receiving an activation instruction or a deactivation instruction for on-demand SSB transmission for the one or more first SCell(s) from the base station via a third signaling; and performing SSB reception on the one or more second SCell(s) when an activation instruction for on-demand SSB transmission for one or more second SCell(s) among the one or more first SCell(s) is received via the third signaling.

[0025] The second signaling and the third signaling utilize at least one medium access control (MAC) control element (CE), and the at least one MAC CE may include a first bitmap for indicating activation or deactivation of the one or more first SCell(s) and a second bitmap(s) for indicating activation or deactivation of on-demand SSB transmission for the one or more first SCell(s).

[0026] According to the embodiments of the present disclosure described above, on-demand SSB and system information transmission for network energy conservation can be efficiently performed. In particular, according to the embodiments of the present disclosure, the configuration of setting information for on-demand SSB transmission and signaling methods for activating / deactivating on-demand SSB transmission can be specified, and the timing for initiating on-demand SSB transmission can be clarified. Accordingly, the overall performance of the communication system can be improved.

[0027] Figure 1 is a conceptual diagram illustrating a first embodiment of a communication system.

[0028] Figure 2 is a block diagram illustrating a first embodiment of a communication node constituting a communication system.

[0029] Figure 3 is a conceptual diagram illustrating a first embodiment of a type 1 frame structure.

[0030] Figure 4 is a conceptual diagram illustrating a first embodiment of a type 2 frame structure.

[0031] FIG. 5 is a conceptual diagram illustrating a first embodiment of a method for transmitting an SS / PBCH block in a communication system.

[0032] FIG. 6 is a conceptual diagram illustrating a first embodiment of an SS / PBCH block in a communication system.

[0033] Fig. 7 is a conceptual diagram illustrating a second embodiment of a method for transmitting an SS / PBCH block in a communication system.

[0034] Figure 8 is a conceptual diagram for explaining the time domain transmission positions of SSBs according to the subcarrier spacing and L.

[0035] FIG. 9a is a conceptual diagram illustrating RMSI CORESET mapping pattern #1 in a communication system, FIG. 9b is a conceptual diagram illustrating RMSI CORESET mapping pattern #2 in a communication system, and FIG. 9c is a conceptual diagram illustrating RMSI CORESET mapping pattern #3 in a communication system.

[0036] Figure 10 is a conceptual diagram illustrating a first embodiment of slot configuration in which PSFCH is set.

[0037] Fig. 11 is a conceptual diagram illustrating a first embodiment of a PSFCH for ACK / NACK transmission.

[0038] FIG. 12 is a conceptual diagram illustrating embodiments of a method for multiplexing a control channel and a data channel in sidelink communication.

[0039] Figure 13 is a conceptual diagram illustrating a first embodiment of a resource selection operation.

[0040] Figure 14 is a conceptual diagram illustrating a first embodiment of a resource re-selection operation.

[0041] Figure 15 is a conceptual diagram illustrating a scenario to which embodiments of the present invention can be applied.

[0042] Figure 16 is a timing diagram for explaining the setup and activation of SCell and the transmission timing of on-demand SSB.

[0043] FIG. 17 is a conceptual diagram illustrating one embodiment of a MAC CE including an indicator indicating whether to transmit on-demand SSB and SCell activation / deactivation information.

[0044] FIG. 18 is a timing diagram for explaining RRC processing delay according to embodiments of the present invention.

[0045] FIGS. 19A and 19B are timing diagrams for explaining a case in which it is determined that on-demand SSB transmission begins after a specific time according to embodiments of the present invention.

[0046] FIGS. 20A to 20D are timing diagrams for explaining a case in which it is determined that on-demand SSB transmission starts from the earliest SSB transmission occasion after a specific time according to embodiments of the present invention.

[0047] The present invention is susceptible to various modifications and embodiments. Specific embodiments are illustrated and described in detail in the drawings. However, this is not intended to limit the present invention to specific embodiments, but rather to encompass all modifications, equivalents, and alternatives falling within the spirit and technical scope of the present invention.

[0048] While terms such as "first" and "second" may be used to describe various components, these components should not be limited by these terms. These terms are used solely to distinguish one component from another. For example, without departing from the scope of the present invention, a first component could be referred to as a "second component," and similarly, a second component could also be referred to as a "first component." The term "and / or" encompasses any combination of multiple related items described herein or any one of multiple related items described herein.

[0049] In the embodiments of the present application, “at least one of A and B” may mean “at least one of A or B” or “at least one of combinations of one or more of A and B.” Furthermore, in the embodiments of the present application, “at least one of A and B” may mean “at least one of A or B” or “at least one of combinations of one or more of A and B.”

[0050] In the embodiments of the present application, (re)transmission may mean “transmission,” “retransmission,” or “transmission and retransmission,” (re)setting may mean “setting,” “resetting,” or “setting and resetting,” (re)connection may mean “connection,” “reconnection,” or “connection and reconnection,” and (re)connection may mean “connection,” “reconnection,” or “connection and reconnection.”

[0051] When a component is referred to as being "connected" or "connected" to another component, it should be understood that it may be directly connected or connected to that other component, but that there may be other components intervening. Conversely, when a component is referred to as being "directly connected" or "connected" to another component, it should be understood that there are no other components intervening.

[0052] The terminology used in this application is only used to describe specific embodiments and is not intended to limit the present invention. The singular expression includes the plural expression unless the context clearly indicates otherwise. In this application, it should be understood that the terms "comprise" or "have" indicate the presence of a feature, number, step, operation, component, part, or combination thereof described in the specification, but do not exclude in advance the possibility of the presence or addition of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

[0053] Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. Terms defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant technology, and will not be interpreted in an idealized or overly formal sense unless explicitly defined herein.

[0054] Hereinafter, with reference to the attached drawings, preferred embodiments of the present invention will be described in more detail. In order to facilitate an overall understanding in describing the present invention, identical reference numerals will be used for identical components in the drawings, and redundant descriptions of identical components will be omitted.

[0055] A communication system to which embodiments of the present invention are applied will be described. The communication system to which embodiments of the present invention are applied is not limited to the scope described below, and embodiments of the present invention can be applied to various communication systems. Here, the term "communication system" can be used interchangeably with "communication network."

[0056] Figure 1 is a conceptual diagram illustrating a first embodiment of a communication system.

[0057] Referring to FIG. 1, the communication system (100) may include a plurality of communication nodes (110-1, 110-2, 110-3, 120-1, 120-2, 130-1, 130-2, 130-3, 130-4, 130-5, 130-6). In addition, the communication system (100) may further include a core network (e.g., a serving-gateway (S-GW), a packet data network (PDN)-gateway (P-GW), a mobility management entity (MME)). If the communication system (100) is a 5G communication system (e.g., a new radio (NR) system), the core network may include an access and mobility management function (AMF), a user plane function (UPF), a session management function (SMF), etc.

[0058] A plurality of communication nodes (110 to 130) can support a communication protocol specified in the 3rd generation partnership project (3GPP) standard (e.g., LTE communication protocol, LTE-A communication protocol, NR communication protocol, etc.). The plurality of communication nodes (110 to 130) may support CDMA (code division multiple access) technology, WCDMA (wideband CDMA) technology, TDMA (time division multiple access) technology, FDMA (frequency division multiple access) technology, OFDM (orthogonal frequency division multiplexing) technology, Filtered OFDM technology, CP (cyclic prefix)-OFDM technology, DFT-s-OFDM (discrete Fourier transform-spread-OFDM) technology, OFDMA (orthogonal frequency division multiple access) technology, SC (single carrier)-FDMA technology, NOMA (non-orthogonal multiple access) technology, GFDM (generalized frequency division multiplexing) technology, FBMC (filter bank multi-carrier) technology, UFMC (universal filtered multi-carrier) technology, SDMA (space division multiple access) technology, etc. Each of the plurality of communication nodes may have the following structure.

[0059] Figure 2 is a block diagram illustrating a first embodiment of a communication node constituting a communication system.

[0060] Referring to FIG. 2, a communication node (200) may include at least one processor (210), a memory (220), and a transmission / reception device (230) that is connected to a network and performs communication. In addition, the communication node (200) may further include an input interface device (240), an output interface device (250), a storage device (260), etc. Each component included in the communication node (200) may be connected by a bus (270) and communicate with each other.

[0061] However, each component included in the communication node (200) may be connected through an individual interface or individual bus centered around the processor (210), rather than a common bus (270). For example, the processor (210) may be connected to at least one of a memory (220), a transmission / reception device (230), an input interface device (240), an output interface device (250), and a storage device (260) through a dedicated interface.

[0062] The processor (210) can execute program commands stored in at least one of the memory (220) and the storage device (260). The processor (210) may refer to a central processing unit (CPU), a graphics processing unit (GPU), or a dedicated processor in which methods according to embodiments of the present invention are performed. Each of the memory (220) and the storage device (260) may be configured with at least one of a volatile storage medium and a non-volatile storage medium. For example, the memory (220) may be configured with at least one of a read-only memory (ROM) and a random access memory (RAM).

[0063] Referring again to FIG. 1, the communication system (100) may include a plurality of base stations (110-1, 110-2, 110-3, 120-1, 120-2) and a plurality of terminals (130-1, 130-2, 130-3, 130-4, 130-5, 130-6). Each of the first base station (110-1), the second base station (110-2), and the third base station (110-3) may form a macro cell. Each of the fourth base station (120-1) and the fifth base station (120-2) may form a small cell. The fourth base station (120-1), the third terminal (130-3), and the fourth terminal (130-4) may be within the cell coverage of the first base station (110-1). The second terminal (130-2), the fourth terminal (130-4), and the fifth terminal (130-5) may be within the cell coverage of the second base station (110-2). The fifth base station (120-2), the fourth terminal (130-4), the fifth terminal (130-5), and the sixth terminal (130-6) may be within the cell coverage of the third base station (110-3). The first terminal (130-1) may be within the cell coverage of the fourth base station (120-1). The sixth terminal (130-6) may be within the cell coverage of the fifth base station (120-2).

[0064] Here, each of the plurality of base stations (110-1, 110-2, 110-3, 120-1, 120-2) may be referred to as a NodeB (NB), an evolved NodeB (eNB), a gNB, an advanced base station (ABS), a high reliability-base station (HR-BS), a base transceiver station (BTS), a radio base station, a radio transceiver, an access point, an access node, a radio access station (RAS), a mobile multihop relay-base station (MMR-BS), a relay station (RS), an advanced relay station (ARS), a high reliability-relay station (HR-RS), a home NodeB (HNB), a home eNodeB (HeNB), a road side unit (RSU), a radio remote head (RRH), a transmission point (TP), a transmission and reception point (TRP), etc.

[0065] Each of the plurality of terminals (130-1, 130-2, 130-3, 130-4, 130-5, 130-6) may be referred to as a user equipment (UE), terminal equipment (TE), advanced mobile station (AMS), high reliability-mobile station (HR-MS), terminal, access terminal, mobile terminal, station, subscriber station, mobile station, portable subscriber station, node, device, OBU (on board unit), etc.

[0066] Meanwhile, each of the plurality of base stations (110-1, 110-2, 110-3, 120-1, 120-2) may operate in a different frequency band or may operate in the same frequency band. Each of the plurality of base stations (110-1, 110-2, 110-3, 120-1, 120-2) may be connected to each other via an ideal backhaul link or a non-ideal backhaul link, and may exchange information with each other via the ideal backhaul link or the non-ideal backhaul link. Each of the plurality of base stations (110-1, 110-2, 110-3, 120-1, 120-2) may be connected to the core network via the ideal backhaul link or the non-ideal backhaul link. Each of the plurality of base stations (110-1, 110-2, 110-3, 120-1, 120-2) can transmit a signal received from the core network to the corresponding terminal (130-1, 130-2, 130-3, 130-4, 130-5, 130-6), and can transmit a signal received from the corresponding terminal (130-1, 130-2, 130-3, 130-4, 130-5, 130-6) to the core network.

[0067] Additionally, each of the plurality of base stations (110-1, 110-2, 110-3, 120-1, 120-2) may support MIMO transmission (e.g., single user (SU)-MIMO, multi user (MU)-MIMO, massive MIMO, etc.), coordinated multipoint (CoMP) transmission, carrier aggregation (CA) transmission, transmission in an unlicensed band, device to device communication (D2D) (or, proximity services (ProSe)), Internet of Things (IoT) communication, dual connectivity (DC), etc. Here, each of the plurality of terminals (130-1, 130-2, 130-3, 130-4, 130-5, 130-6) can perform an operation corresponding to the base station (110-1, 110-2, 110-3, 120-1, 120-2) and an operation supported by the base station (110-1, 110-2, 110-3, 120-1, 120-2). For example, the second base station (110-2) can transmit a signal to the fourth terminal (130-4) based on the SU-MIMO scheme, and the fourth terminal (130-4) can receive a signal from the second base station (110-2) by the SU-MIMO scheme. Alternatively, the second base station (110-2) can transmit signals to the fourth terminal (130-4) and the fifth terminal (130-5) based on the MU-MIMO method, and each of the fourth terminal (130-4) and the fifth terminal (130-5) can receive signals from the second base station (110-2) based on the MU-MIMO method.

[0068] Each of the first base station (110-1), the second base station (110-2), and the third base station (110-3) can transmit a signal to the fourth terminal (130-4) based on the CoMP scheme, and the fourth terminal (130-4) can receive a signal from the first base station (110-1), the second base station (110-2), and the third base station (110-3) based on the CoMP scheme. Each of the plurality of base stations (110-1, 110-2, 110-3, 120-1, 120-2) can transmit and receive a signal with terminals (130-1, 130-2, 130-3, 130-4, 130-5, 130-6) within its cell coverage based on the CA scheme. Each of the first base station (110-1), the second base station (110-2), and the third base station (110-3) can control D2D between the fourth terminal (130-4) and the fifth terminal (130-5), and each of the fourth terminal (130-4) and the fifth terminal (130-5) can perform D2D under the control of the second base station (110-2) and the third base station (110-3).

[0069] Meanwhile, a communication system can support three types of frame structures. The Type 1 frame structure can be applied to a frequency division duplex (FDD) communication system, the Type 2 frame structure can be applied to a time division duplex (TDD) communication system, and the Type 3 frame structure can be applied to an unlicensed band-based communication system (e.g., a licensed assisted access (LAA) communication system).

[0070] Figure 3 is a conceptual diagram illustrating a first embodiment of a type 1 frame structure.

[0071] Referring to FIG. 3, a radio frame (300) may include 10 subframes, and a subframe may include 2 slots. Accordingly, the radio frame (300) may include 20 slots (e.g., slot #0, slot #1, slot #2, slot #3, slot #18, slot #19). The length (Tf) of the radio frame (300) may be 10 ms (milliseconds), the subframe length may be 1 ms, and the slot length (Tslot) may be 0.5 ms. Here, Ts may indicate a sampling time and may be 1 / 30,720,000 s (second).

[0072] A slot may be composed of multiple OFDM symbols in the time domain and multiple resource blocks (RBs) in the frequency domain. A RB may be composed of multiple subcarriers in the frequency domain. The number of OFDM symbols constituting a slot may vary depending on the configuration of a cyclic prefix (CP). CPs can be classified into normal CPs and extended CPs. When a normal CP is used, a slot may be composed of 7 OFDM symbols, in which case a subframe may be composed of 14 OFDM symbols. When an extended CP is used, a slot may be composed of 6 OFDM symbols, in which case a subframe may be composed of 12 OFDM symbols.

[0073] Figure 4 is a conceptual diagram illustrating a first embodiment of a type 2 frame structure.

[0074] Referring to FIG. 4, a radio frame (400) may include two half frames, and a half frame may include five subframes. Therefore, a radio frame (400) may include ten subframes. The length (Tf) of the radio frame (400) may be 10 ms. The length of a half frame may be 5 ms. The length of a subframe may be 1 ms. Here, Ts may be 1 / 30,720,000 s.

[0075] The radio frame (400) may include a downlink subframe, an uplink subframe, and a special subframe. Each of the downlink subframe and the uplink subframe may include two slots. The slot length (Tslot) may be 0.5 ms. Among the subframes included in the radio frame (400), each of subframe #1 and subframe #6 may be a special subframe. For example, when the downlink-uplink switching period is 5 ms, the radio frame (400) may include two special subframes. Alternatively, when the downlink-uplink switching period is 10 ms, the radio frame (400) may include one special subframe. The special subframe may include a downlink pilot time slot (DwPTS), a guard period (GP), and an uplink pilot time slot (UpPTS).

[0076] The downlink pilot time slot can be considered a downlink period and can be used for cell search, time and frequency synchronization acquisition, channel estimation, etc. of the terminal. The guard period can be used to solve the interference problem of uplink data transmission caused by the delay in downlink data reception. In addition, the guard period can include the time required for switching from downlink data reception operation to uplink data transmission operation. The uplink pilot time slot can be used for uplink channel estimation, time and frequency synchronization acquisition, etc. The transmission of a physical random access channel (PRACH) or a sounding reference signal (SRS) can be performed in the uplink pilot time slot.

[0077] The lengths of each of the downlink pilot time slot, guard interval, and uplink pilot time slot included in the special subframe can be variably adjusted as needed. In addition, the number and location of each of the downlink subframes, uplink subframes, and special subframes included in the radio frame (400) can be changed as needed.

[0078] In a communication system, a transmission time interval (TTI) may be a basic time unit for transmitting encoded data through a physical layer. A short TTI may be used to support low-latency requirements in a communication system. The length of a short TTI may be less than 1 ms. A conventional TTI with a length of 1 ms may be referred to as a base TTI or a regular TTI. That is, a base TTI may consist of one subframe. To support transmission in a basic TTI unit, signals and channels may be configured on a subframe basis. For example, a cell-specific reference signal (CRS), a physical downlink control channel (PDCCH), a physical downlink shared channel (PDSCH), a physical uplink control channel (PUCCH), and a physical uplink shared channel (PUSCH) may exist in each subframe.

[0079] On the other hand, synchronization signals (e.g., primary synchronization signal (PSS), secondary synchronization signal (SSS)) can exist every 5 subframes, and physical broadcast channel (PBCH) can exist every 10 subframes. In addition, radio frames can be distinguished by SFN, and SFN can be used to define transmission of signals whose transmission period is longer than one radio frame (e.g., paging signals, reference signals for channel estimation, signals indicating channel state information, etc.). The period of SFN can be 1024.

[0080] In an LTE system, the PBCH may be a physical layer channel used to transmit system information (e.g., master information block (MIB)). The PBCH may be transmitted every 10 subframes. That is, the transmission period of the PBCH may be 10 ms, and the PBCH may be transmitted once in a radio frame. The same MIB may be transmitted over four consecutive radio frames, and the MIB may change after four consecutive radio frames depending on the circumstances of the LTE system. The transmission period of the same MIB may be referred to as a "PBCH TTI," and the PBCH TTI may be 40 ms. That is, the MIB may change for each PBCH TTI.

[0081] The MIB can be composed of 40 bits. Of the 40 bits that make up the MIB, 3 bits can be used to indicate the system bandwidth, 3 bits can be used to indicate information related to the physical hybrid ARQ (automatic repeat request) indicator channel (PHICH), 8 bits can be used to indicate the SFN, 10 bits can be set as reserved bits, and 16 bits can be used for the CRC (cyclic redundancy check).

[0082] The SFN that distinguishes a radio frame can be composed of a total of 10 bits (B9 to B0), and among the 10 bits, the most significant bit (MSB) 8 bits (B9 to B2) can be indicated by the PBCH (i.e., MIB). The 8 MSB bits (B9 to B2) of the SFN indicated by the PBCH (i.e., MIB) can be the same during four consecutive radio frames (i.e., PBCH TTI). The two least significant bit (LSB) bits (B1 to B0) of the SFN can change during four consecutive radio frames (i.e., PBCH TTI) and may not be explicitly indicated by the PBCH (i.e., MIB). The two LSB bits (B1 to B0) of the SFN can be implicitly indicated by a scrambling sequence for the PBCH (hereinafter, referred to as "PBCH scrambling sequence").

[0083] A gold sequence initialized with a cell ID as the PBCH scrambling sequence can be used, and the PBCH scrambling sequence can be initialized every four consecutive radio frames (i.e., PBCH TTI) according to mod(SFN,4). A PBCH transmitted in a radio frame corresponding to an SFN in which the LSB 2 bits (B1 to B0) are set to "00" can be scrambled by the gold sequence initialized with the cell ID. Thereafter, gold sequences generated according to mod(SFN,4) can be used to scramble a PBCH transmitted in a radio frame in which the LSB 2 bits (B1 to B0) of the SFN are "01", "10", and "11".

[0084] Therefore, a terminal that acquires a cell ID during the initial cell search process can implicitly find out the values ​​of the LSB 2 bits (B1 to B0) of the SFN (e.g., "00", "01", "10", "11") through the PBCH scrambling sequence during the decoding process of the PBCH (i.e., MIB). The terminal can use the LSB 2 bits (B1 to B0) of the SFN identified based on the PBCH scrambling sequence and the MSB 8 bits (B9 to B2) of the SFN indicated by the PBCH (i.e., MIB) to identify the SFN (i.e., the entire bits (B9 to B0) of the SFN).

[0085]

[0086] Evolving mobile communication networks beyond LTE must meet technical requirements to support a wider range of service scenarios, beyond the traditional focus on high transmission speeds. Recently, the International Telecommunication Union (ITU-R) defined key performance indicators (KPIs) and requirements for IMT-2020, the official name for 5G mobile communications. These can be summarized as high transmission speeds (eMBB, enhanced Mobile Broadband), low transmission latency (URLLC, Ultra Reliable Low Latency Communication), and massive machine type communication (mMTC). According to the ITU-R's anticipated schedule, the goal is to allocate frequencies for IMT-2020 in 2019 and complete international standard approval by 2020.

[0087] 3GPP is developing a 5G standard based on a new radio access technology (RAT) that meets the IMT-2020 requirements. According to 3GPP's definition, the new radio access technology is a radio access technology that is not backward compatible with existing 3GPP radio access technologies. New wireless communication systems after LTE that adopt this radio access technology are referred to as NR (New Radio) in this specification.

[0088] One of the key differences between NR and existing 3GPP systems like CDMA and LTE is its ability to utilize a wide range of frequency bands to increase transmission capacity. In this regard, the ITU-hosted World Radio Conference (WRC-15) has set the 24.25-86 GHz band as a candidate frequency band for IMT-2020 as an agenda item for the next WRC-19. 3GPP is considering bands from sub-1 GHz to 100 GHz as candidate NR bands.

[0089] Among the waveform technologies being discussed for NR, OFDM (Orthogonal Frequency Division Multiplexing), Filtered OFDM, GFDM (Generalized Frequency Division Multiplexing), FBMC (Filter Bank Multi-Carrier), and UFMC (Universal Filtered Multi-Carrier) are candidates. Although each has its own advantages and disadvantages, CP (Cyclic prefix)-based OFDM and SC-FDMA (Single Carrier-Frequency Division Multiple Access) are still effective methods for 5G systems due to their relatively low implementation complexity at the transmitter and receiver and MIMO (Multiple-Input Multiple-Output) scalability. However, in order to flexibly support various 5G usage scenarios, a method of simultaneously accommodating different waveform parameters on a single carrier without a guard band can be considered. For this purpose, Filtered OFDM or GFDM, which have a frequency spectrum with small out-of-band emissions (OOB), may be suitable.

[0090] For convenience of explanation, the present invention assumes CP-based OFDM as the waveform technology for wireless access. However, this is merely for convenience of explanation, and the various embodiments of the present invention are not limited to any specific waveform technology. Generally, the category of CP-based OFDM technologies also includes Filtered OFDM and Spread Spectrum OFDM (e.g., DFT-spread OFDM).

[0091]

[0092] The subcarrier spacing of a communication system (e.g., an OFDM-based communication system) can be determined based on factors such as carrier frequency offset (CFO). CFO can be caused by the Doppler effect, phase drift, etc., and can increase in proportion to the operating frequency. Therefore, to prevent performance degradation of the communication system due to CFO, the subcarrier spacing can increase in proportion to the operating frequency. On the other hand, as the subcarrier spacing increases, the CP overhead can increase. Therefore, the subcarrier spacing can be set based on channel characteristics according to the frequency band, radio frequency (RF) characteristics, etc.

[0093] NR systems consider various numerologies. For example, the subcarrier spacing in a communication system can be set to 15 kHz, 30 kHz, 60 kHz, or 120 kHz. The subcarrier spacing in an LTE system can be 15 kHz, while in an NR system, the subcarrier spacing can be 1, 2, 4, or 8 times the existing 15 kHz subcarrier spacing. When the subcarrier spacing increases by exponential multiples of the existing subcarrier spacing, the frame structure can be easily designed.

[0094] Communication systems can support a wide frequency band (e.g., hundreds of megahertz to tens of gigahertz). Because the diffraction and reflection characteristics of radio waves are poor in high-frequency bands, propagation loss (e.g., path loss, reflection loss, etc.) in high-frequency bands can be greater than propagation loss in low-frequency bands. Consequently, the cell coverage of a communication system supporting a high-frequency band may be less than that of a communication system supporting a low-frequency band. To address this issue, beamforming based on multiple antenna elements can be used to increase cell coverage in communication systems supporting high-frequency bands.

[0095] Beamforming methods may include digital beamforming, analog beamforming, and hybrid beamforming. In a communication system using a digital beamforming method, beamforming gain can be obtained by using multiple RF paths based on a digital precoder or codebook. In a communication system using an analog beamforming method, beamforming gain can be obtained by using analog RF devices (e.g., phase shifters, power amplifiers (PAs), variable gain amplifiers (VGAs), etc.) and antenna arrays.

[0096] Because digital beamforming requires expensive digital-to-analog converters (DACs) or analog-to-digital converters (ADCs) and transceiver units corresponding to the number of antenna elements, the complexity of antenna implementation may increase to increase beamforming gain. In communication systems using analog beamforming, since multiple antenna elements are connected to a single transceiver unit through phase shifters, the complexity of antenna implementation may not increase significantly even when the beamforming gain is increased. However, the beamforming performance of communication systems using analog beamforming may be lower than that of communication systems using digital beamforming. Furthermore, since the phase shifter in communication systems using analog beamforming is controlled in the time domain, frequency resources may not be used efficiently. Therefore, a hybrid beamforming method that combines digital and analog methods may be used.

[0097] When cell coverage is increased by using beamforming, not only the control channel and data channel of each terminal, but also the common control channel and common signal (e.g., reference signal, synchronization signal) for all terminals belonging to the cell coverage can be transmitted based on the beamforming method. When transmitting the common control channel and signal to all terminals while increasing cell coverage by applying beamforming, it is difficult to transmit the common control channel and signal to the entire cell coverage with a single transmission, and the common control channel and signal must be transmitted through multiple beams several times over a certain period of time. This transmission over multiple periods of time while switching multiple beams is called beam sweeping. When transmitting the common control channel and signal by applying beamforming, this beam sweeping operation is absolutely necessary.

[0098]

[0099] A terminal accessing the system can obtain downlink frequency / time synchronization and cell ID information using a synchronization signal, and then obtain uplink synchronization and form a radio link through a random access procedure. At this time, in the NR system, a SS / PBCH (synchronization block / physical broadcast channel) block can also be transmitted using a beam sweeping method. The SS / PBCH block can be composed of a PSS, an SSS, a PBCH, etc., and the PSS, SSS, and PBCH within the SS / PBCH block can be configured using a TDM (time division multiplexing) method. The SS / PBCH block may also be referred to as an "SS block (SSB)." One SS / PBCH block can be transmitted using N consecutive OFDM symbols. Here, N can be an integer greater than or equal to 4. The base station can periodically transmit the SS / PBCH block, and the terminal can obtain frequency / time synchronization, a cell ID, system information, etc. based on the SS / PBCH block received from the base station. SS / PBCH blocks can be transmitted as follows:

[0100] FIG. 5 is a conceptual diagram illustrating a first embodiment of a method for transmitting an SS / PBCH block in a communication system.

[0101] Referring to FIG. 5, one or more SS / PBCH blocks within an SS / PBCH block burst set may be transmitted in a beam sweeping manner. Up to L SS / PBCH blocks may be transmitted within one SS / PBCH block burst set. L may be an integer greater than or equal to 2 and may be defined in the 3GPP standard. L may vary depending on the system frequency domain. SS / PBCH blocks within an SS / PBCH block burst set may be positioned consecutively or distributedly. Consecutive SS / PBCH blocks may be referred to as an "SS / PBCH block burst." An SS / PBCH block burst set may be repeated periodically, and system information (e.g., MIB) transmitted via the PBCH of SS / PBCH blocks within an SS / PBCH block burst set may be the same. SS / PBCH block index, SS / PBCH block burst index, OFDM symbol index, slot index, etc. can be explicitly or implicitly indicated by PBCH.

[0102] FIG. 6 is a conceptual diagram illustrating a first embodiment of an SS / PBCH block in a communication system.

[0103] Referring to FIG. 6, the arrangement order within the SS / PBCH block may be "PSS *?*→? SSS →? PBCH". Within the SS / PBCH block, the PSS, SSS, and PBCH may be configured in a TDM manner. In a symbol where the SSS is located, the PBCH may be arranged in frequency resources higher than and lower than the SSS. When the maximum number of SS / PBCH blocks is 8 in a frequency band below 6 GHz, the index of the SS / PBCH block may be identified based on a demodulation reference signal (DMRS) (hereinafter referred to as "PBCH DMRS") used for demodulation of the PBCH. When the maximum number of SS / PBCH blocks is 64 in a frequency band above 6 GHz, among the 6 bits indicating the index of the SS / PBCH block, the 3 LSB bits may be identified based on the PBCH DMRS, and the remaining 3 MSB bits may be identified based on the PBCH payload.

[0104] The maximum system bandwidth supported by an NR system may be 400 MHz. The maximum bandwidth supported by a terminal may vary depending on its capabilities. Therefore, a terminal may perform an initial access procedure (e.g., an initial connection procedure) using a portion of the system bandwidth of an NR system that supports wideband. To support the access procedure for terminals that support various bandwidths, SS / PBCH blocks may be multiplexed along the frequency axis within the system bandwidth of a wideband NR system. In this case, SS / PBCH blocks may be transmitted as follows.

[0105] Fig. 7 is a conceptual diagram illustrating a second embodiment of a method for transmitting an SS / PBCH block in a communication system.

[0106] Referring to FIG. 7, a wideband component carrier (CC) may include multiple bandwidth parts (BWPs). For example, a wideband CC may include four BWPs. A base station may transmit an SS / PBCH block in each of BWPs #0 to #3 belonging to the wideband CC. A terminal may receive an SS / PBCH block in one or more BWPs among BWPs #0 to #3 and perform an initial access procedure using the received SS / PBCH block.

[0107] After detecting an SS / PBCH block, the terminal can obtain system information (e.g., remaining minimum system information (RMSI)) and perform a cell access procedure based on the system information. The RMSI can be transmitted through a PDSCH scheduled by a PDCCH. Configuration information of a CORESET (control resource set) on which a PDCCH including scheduling information of a PDSCH on which the RMSI is transmitted can be transmitted through a PBCH within the SS / PBCH block. A plurality of SS / PBCH blocks can be transmitted over the entire system bandwidth, and among the plurality of SS / PBCH blocks, one or more SS / PBCH blocks can be SS / PBCH blocks associated with an RMSI. The remaining SS / PBCH blocks may not be associated with an RMSI. An SS / PBCH block associated with an RMSI can be defined as a "cell-defining SS / PBCH block." The terminal can perform a cell search procedure and an initial access procedure using the cell-defining SS / PBCH block. SS / PBCH blocks not associated with RMSI may be used for synchronization and / or measurement procedures in the corresponding BWP. The BWP in which the SS / PBCH block is transmitted may be limited to one or more BWPs within a wide bandwidth.

[0108] RMSI can be obtained by performing "an operation of receiving RMSI through an operation of acquiring scheduling information of PDSCH from an operation of detecting PDCCH based on the configuration information of an operation of acquiring configuration information of CORESET from an SS / PBCH block (e.g., PBCH) *?*". The transmission resource of the PDCCH can be configured by the configuration information of the CORESET. The RMSI CORESET mapping pattern can be defined as follows. The RMSI CORESET can be a CORESET used for transmitting and receiving RMSI.

[0109] Figure 8 is a conceptual diagram for explaining the time domain transmission positions of SSBs according to the subcarrier spacing and L.

[0110] The time domain locations where SSB is transmitted can be defined differently depending on the subcarrier spacing and L value. In the symbol(s) where SSB is not transmitted within a slot, short UL transmissions such as Uplink Control Information (UCI) can be performed. In SSB transmissions with large subcarrier spacing (e.g., 120 kHz or 240 kHz SCS), a gap can be set in the middle of consecutive slots containing SSB to allow long UL transmissions such as URLLC traffic to be performed at least every 1 ms.

[0111] As in the example of FIG. 8, a gap for UL transmission may be set after 8 slots containing SSBs with a 120 kHz subcarrier spacing, and a gap for UL transmission may be set after 16 slots containing SSBs with a 240 kHz subcarrier spacing.

[0112] As described above, the transmission possible locations are set so that up to L SSB transmissions are possible within an SSB burst set, and the L value has different values ​​depending on the frequency domain. For example, in FR1, up to 4 SSB transmissions are possible between 0 and 3 GHz, up to 8 SSB transmissions are possible thereafter, and up to 64 SSB transmissions are possible in FR2. At this time, depending on the environment, the system may transmit actual SSBs at all L locations or use only some of L for actual SSB transmission. At this time, when a terminal receiving data receives data at a location where SSB transmission is possible, the terminal determines whether to rate-match the received data based on whether actual SSB transmission is performed at the location. At this time, information about the location where the SSB is actually transmitted can be transmitted to the terminal through RMSI and / or UE-specific RRC signaling. When transmitted via RMSI, when L=4 or 8, the location where the actual SSB is transmitted is indicated as '1' through bitmap information, and the location where the SSB is not transmitted is indicated as '0'. When L=64, 64 location information is transmitted in a compressed form of 16 bits. More specifically, L=64 SSBs are divided into 8 groups of 8 each, and 8 SSBs within a group are represented by 8-bit bitmaps, and each of the 8 groups is represented by an 8-bit bitmap, so that the bitmap is composed of 16 bits in total. Therefore, all groups have the same SSB transmission pattern within the group.

[0113] As described above, RMSI reception is achieved through a series of processes: detecting PDCCH through CORESET configuration information transmitted through PBCH, obtaining RMSI scheduling information through this, and then receiving PDSCH accordingly. At this time, the control channel resource area where PDCCH can be transmitted is set through RMSI CORESET configuration information, which can have three major patterns as follows.

[0114] FIG. 9a is a conceptual diagram illustrating RMSI CORESET mapping pattern #1 in a communication system, FIG. 9b is a conceptual diagram illustrating RMSI CORESET mapping pattern #2 in a communication system, and FIG. 9c is a conceptual diagram illustrating RMSI CORESET mapping pattern #3 in a communication system.

[0115] Referring to FIGS. 9A to 9C, one RMSI CORESET mapping pattern among RMSI CORESET mapping patterns #1 to #3 can be used, and detailed settings can be completed according to one RMSI CORESET mapping pattern. In RMSI CORESET mapping pattern #1, SS / PBCH block, CORESET (e.g., RMSI CORESET), and PDSCH (e.g., RMSI PDSCH) can be configured in a TDM manner. RMSI PDSCH can mean PDSCH on which RMSI is transmitted. In RMSI CORESET mapping pattern #2, CORESET (e.g., RMSI CORESET) and PDSCH (e.g., RMSI PDSCH) can be configured in a TDM manner, and PDSCH (e.g., RMSI PDSCH) can be configured in an SS / PBCH block and an FDM (frequency division multiplexing) manner. In RMSI CORESET mapping pattern #3, CORESET (e.g., RMSI CORESET) and PDSCH (e.g., RMSI PDSCH) can be configured in TDM manner, and CORESET (e.g., RMSI CORESET) and PDSCH (e.g., RMSI PDSCH) can be configured in SS / PBCH block and FDM manner.

[0116] In the frequency band below 6 GHz, only RMSI CORESET mapping pattern #1 can be used. In the frequency band above 6 GHz, all of RMSI CORESET mapping patterns #1, #2, and #3 can be used. The numerology of the SS / PBCH block can be different from the numerology of "RMSI CORESET and RMSI PDSCH". Here, the numerology can be subcarrier spacing. In RMSI CORESET mapping pattern #1, any combination of numerologies can be used. In RMSI CORESET mapping pattern #2, any combination of "SS / PBCH block, RMSI CORESET / PDSCH = 120 kHz, 60 kHz or 240 kHz, 120 kHz" can be used. In RMSI CORESET mapping pattern #3, the combination of "SS / PBCH block, RMSI CORESET / PDSCH = 120kHz, 120kHz" can be used.

[0117] According to the combination of the numerology of the SS / PBCH block and the numerology of the RMSI CORESET / PDSCH, one RMSI CORESET mapping pattern may be selected from RMSI CORESET mapping patterns #1-3. Configuration information of the RMSI CORESET may include tables A and B. Table A may indicate the number of RBs (resource blocks) of the RMSI CORESET, the number of symbols of the RMSI CORESET, and the offset between the RB of the SS / PBCH block (e.g., a start RB or an end RB) and the RB of the RMSI CORESET (e.g., a start RB or an end RB). Table B may indicate the number of search space sets per slot, the offset of the RMSI CORESET, and the OFDM symbol index in each of the RMSI CORESET mapping patterns. Table B may indicate information for configuring a monitoring occasion of the RMSI PDCCH. Each of Table A and Table B may be composed of multiple tables. For example, Table A may include Tables 13-1 to 13-8 as specified in TS 38.213, and Table B may include Tables 13-9 to 13-13 as specified in TS 38.213. The size of each of Table A and Table B may be 4 bits.

[0118] In the NR system, PDSCH can be mapped to the time domain according to PDSCH mapping type A or B. PDSCH mapping types A and B can be defined as shown in Table 1 below.

[0119] PDSCH Mapping Type Normal CP Extended CPSLS+LSLS+L Type A{0,1,2,3}(Note 1){3,...}{3,...}{0,1,2,3}(Note 1){3,...}{3,...}Type B{0,...,12}{2,4,7}{2,...}{0,...,10}{2,4,6}{2,...}Note 1: S = 3 is applicable only if dmrs-TypeA-Posiition= 3

[0120] Type A (i.e., PDSCH mapping type A) may be slot-based transmission. When Type A is used, the position of the start symbol of the PDSCH may be set to one of {0, 1, 2, 3}. When Type A and a normal CP are used, the number of symbols constituting the PDSCH (e.g., the duration of the PDSCH) may be set to one of 3 to 14 within a symbol boundary. Type B (i.e., PDSCH mapping type B) may be non-slot-based transmission. When Type B is used, the position of the start symbol of the PDSCH may be set to one of 0 to 12. When Type B and a normal CP are used, the number of symbols constituting the PDSCH (e.g., the duration of the PDSCH) may be set to one of {2, 4, 7} within a symbol boundary. A DMRS (hereinafter referred to as "PDSCH DMRS") for demodulating a PDSCH (e.g., data) may be determined based on an ID indicating a PDSCH mapping type (e.g., Type A, Type B) and a length. The ID may be defined differently depending on the PDSCH mapping type.

[0121]

[0122] As the NR phase 1 standardization is finalized in Rel-15 and phase 2 standardization begins in Rel-16, new features are being discussed in the NR system. One of the most representative features is NR-U (Unlicensed). NR-U is a technology that supports operation in unlicensed spectrum used for purposes such as Wi-Fi in order to increase network capacity by increasing the utilization of limited frequency resources. It was standardized as LTE-LAA (Licensed-Assisted Access) technology in Rel-13 and has continued to evolve through LTE-eLAA (Enhanced LAA) in Rel-14 and LTE-FeLAA (Futher Enhanced LAA) in Rel-15. Following the SI for NR-U, standardization work is also underway through WI in Rel-16.

[0123] In the NR-U system, the terminal can determine whether a signal is transmitted from the base station based on the DRS (Discovery Reference Signal) received from the base station, just like in the general NR system. In the NR-U system in SA (Stand-Alone) mode, the terminal can obtain synchronization and / or system information based on the DRS. In the NR-U system, the DRS can be transmitted according to the regulations of the unlicensed band (e.g., transmission band, transmission power, transmission time, etc.). For example, according to the Occupied Channel Bandwidth (OCB) regulations, the signal can be configured and / or transmitted so as to occupy 80% of the total channel bandwidth (e.g., 20 MHz).

[0124] In an NR-U system, a communication node (e.g., a base station, a terminal) may perform LBT (Listen Before Talk) before transmitting a signal and / or channel for coexistence with other systems. The signal may be a synchronization signal, a reference signal (e.g., DRS, DMRS, CSI (channel state information)-RS, PT (phase tracking)-RS, SRS (sounding reference signal)), etc. The channel may be a downlink channel, an uplink channel, a sidelink channel, etc. In embodiments, the signal may mean "signal," "channel," or "signal and channel." LBT may be an operation to check whether a signal is transmitted by another communication node. If it is determined by LBT that there is no transmission signal (e.g., if LBT is successful), the communication node may transmit a signal in an unlicensed band. If it is determined by LBT that there is a transmission signal (e.g., if LBT fails), the communication node may not transmit a signal in the unlicensed band. Communication nodes can perform LBT according to various categories before transmitting a signal. The LBT category may vary depending on the type of transmitted signal.

[0125]

[0126] Meanwhile, NR V2X (vehicular-to-everything) communication technology is being discussed at the NR standardization meeting. NR V2X communication technology, based on device-to-device (D2D) communication technology, can support communication between vehicles, between vehicles and infrastructure, and between vehicles and pedestrians. Technologies to reduce power consumption and improve reliability for NR V2X communication are also being discussed.

[0127] NR V2X communication (e.g., sidelink communication) can be performed according to three transmission methods (e.g., unicast, broadcast, and groupcast). When the unicast method is used, a PC5-RRC connection can be established between a first terminal (e.g., a transmitting terminal that transmits data) and a second terminal (e.g., a receiving terminal that receives data), and the PC5-RRC connection can mean a logical connection for a pair between a source ID of the first terminal and a destination ID of the second terminal. The first terminal can transmit data (e.g., sidelink data) to the second terminal. When the broadcast method is used, the first terminal can transmit data to all terminals. When the groupcast method is used, the first terminal can transmit data to a group consisting of multiple terminals (e.g., a groupcast group). In SL communication (e.g., SL-U communication), a transmitting terminal may mean a terminal that transmits data, and a receiving terminal may mean a terminal that receives data.

[0128] When a unicast method is used, the second terminal can transmit feedback information (e.g., ACK (acknowledgement) or NACK (negative ACK)) regarding data received from the first terminal to the first terminal. In the embodiments below, the feedback information may be referred to as "HARQ-ACK", "feedback signal", "PSFCH (physical sidelink feedback channel) signal", etc. If an ACK is received from the second terminal, the first terminal can determine that the data has been successfully received by the second terminal. If a NACK is received from the second terminal, the first terminal can determine that the second terminal has failed to receive the data. In this case, the first terminal can transmit additional information to the second terminal based on a hybrid automatic repeat request (HARQ) method. Alternatively, the first terminal can improve the probability of data reception by the second terminal by retransmitting the same data to the second terminal.

[0129] When broadcasting is used, the process of transmitting feedback information about data may not be performed. For example, system information may be transmitted via broadcasting, and the terminal may not transmit feedback information about the system information to the base station. Therefore, the base station may not know whether the terminal has successfully received the system information. To address this issue, the base station may periodically broadcast system information.

[0130] When the groupcast method is used, the feedback information transmission procedure for data may not be performed. For example, necessary information may be transmitted periodically via the groupcast method without the feedback information transmission procedure. However, if the target and / or number of terminals participating in communication based on the groupcast method are limited, and the data transmitted via the groupcast method is data that must be received within a preset time (e.g., delay-sensitive data), the feedback information transmission procedure may also be required in the groupcast sidelink communication. The groupcast sidelink communication may refer to sidelink communication performed via the groupcast method. If the feedback information transmission procedure is performed in the groupcast sidelink communication, data can be transmitted and received efficiently and reliably.

[0131] In groupcast sidelink communication, two HARQ-ACK feedback schemes (e.g., procedures for transmitting feedback information) may be supported. "If there are a large number of receiving terminals in a sidelink group and service scenario 1 is supported," some receiving terminals within a specific range within the sidelink group may transmit a NACK via PSFCH when data reception fails. This scheme may be "groupcast HARQ-ACK feedback option 1." In service scenario 1, some receiving terminals within a specific range may be allowed to receive in a best-effort manner instead of all receiving terminals within the sidelink group. Service scenario 1 may be an extended sensor scenario in which some receiving terminals within a specific range need to receive the same sensor information from a transmitting terminal. In embodiments, a transmitting terminal may refer to a terminal transmitting data, and a receiving terminal may refer to a terminal receiving data.

[0132] "If the number of receiving terminals in a sidelink group is limited and service scenario 2 is supported", each receiving terminal belonging to the sidelink group can individually report HARQ-ACK for data through a separate PSFCH. This method may be "Groupcast HARQ-ACK feedback option 2". In service scenario 2, since PSFCH resources are sufficient, the transmitting terminal can monitor HARQ-ACK feedback from all receiving terminals belonging to the sidelink group, and data reception by all receiving terminals belonging to the sidelink group can be guaranteed.

[0133] As with broadcast sidelink communications, data can be transmitted and received without the HARQ-ACK feedback procedure in unicast sidelink communications and groupcast sidelink communications. In this case, to increase the probability of data reception, the transmitting terminal can retransmit data a preset number of times.

[0134] In all transmission methods (e.g., unicast transmission, groupcast transmission, broadcast transmission), whether to apply the HARQ-ACK feedback procedure can be fixedly or semi-fixedly configured to the terminal(s) through signaling (e.g., signaling of system information, PC5-RRC signaling, UE-specific RRC signaling, signaling of control information). In sidelink communication, HARQ-ACK feedback information can be transmitted on the PSFCH. If the PSSCH reception is successful, the receiving terminal can transmit an ACK for the PSSCH (e.g., data) on the PSFCH. If the PSSCH reception is unsuccessful, the receiving terminal can transmit a NACK for the PSSCH (e.g., data) on the PSFCH. The PSFCH can be a channel for reporting ACK / NACK information (e.g., HARQ-ACK feedback) to the transmitting terminal. A resource region (e.g., a PSFCH resource region) for PSFCH transmission (e.g., transmission of HARQ-ACK feedback) within a specific resource pool may be preset. The PSFCH (e.g., PSFCH resource, PSFH resource region) may be configured periodically. A PSFCH period for the PSFCH resource may be k slots (e.g., logical SL (sidelink) slots). k may be a natural number. For example, k may be 1, 2, or 4.

[0135] Figure 10 is a conceptual diagram illustrating a first embodiment of slot configuration in which PSFCH is set.

[0136] Referring to FIG. 10, within a slot (e.g., SL slot), a PSFCH (e.g., HARQ-ACK feedback) may be repeatedly transmitted in two symbols (e.g., two OFDM symbols). The first of the two symbols in which the PSFCH is transmitted may be used for automatic gain control (AGC) purposes to adjust the correct PSFCH receive power level.

[0137] The PSFCH can be transmitted within a frequency resource region preset by system information. In this case, the frequency resource region for PSFCH transmission can be indicated (e.g., signaled) in the form of a bitmap within a resource pool. The receiving terminal can implicitly select the location of the frequency resource region for PSFCH transmission based on the slot and subchannel index in which the PSSCH is received. The receiving terminal can check the number of PSFCH resources that can be multiplexed based on the cyclic shift of the resource block (RB) and the PSFCH sequence within the frequency resource region. The receiving terminal can implicitly select the PSFCH index for the PSFCH resource(s) based on the source ID (identifier) ​​and the member ID. The source ID can be a physical layer source ID. The source ID can be the ID of the transmitting terminal that transmitted the PSSCH.

[0138] The member ID can be used in groupcast HARQ-ACK feedback option 2. When groupcast HARQ-ACK feedback option 2 is applied, each receiving terminal in the group can individually transmit HARQ-ACK feedback for SL data through a separate PSFCH (e.g., PSFCH resource). In other cases than the above embodiment, the member ID can be set to 0.

[0139] Fig. 11 is a conceptual diagram illustrating a first embodiment of a PSFCH for ACK / NACK transmission.

[0140] Referring to FIG. 11, the transmission time of the PSFCH may be the first slot (e.g., the PSFCH slot) in which PSFCH transmission is possible after a preset time (e.g., sl-MinTimeGapPSFCH) from the reception time of the PSSCH. The PSFCH slot may be a slot in which PSFCH transmission is possible and / or a slot in which a PSFCH is set. sl-MinTimeGapPSFCH may be set in consideration of "the time to process the PSSCH after reception of the PSSCH" and "the time to prepare ACK / NACK (e.g., HARQ-ACK feedback) depending on whether the PSSCH is successfully received." sl-MinTimeGapPSFCH may be set to two or three slots. A terminal (e.g., a receiving terminal) may transmit the PSFCH in slot #n+12, which is a slot in which PSFCH transmission is possible after sl-MinTimeGapPSFCH (e.g., three slots) from the reception time of the PSSCH. n may be an integer greater than or equal to 0. In the present disclosure, the reception time may mean the reception start time and / or the reception end time, and the transmission time may mean the transmission start time and / or the transmission end time. The time point may mean time and / or duration.

[0141]

[0142] Data reliability at a receiving terminal can be improved by appropriately adjusting the power of the transmitting terminal according to the transmission environment. Interference to other terminals can be mitigated by appropriately adjusting the power of the transmitting terminal. Energy efficiency can be improved by reducing unnecessary transmission power. Power control methods can be classified into open-loop power control and closed-loop power control. In open-loop power control, the transmitting terminal can determine the transmission power considering the configured and measured environment. In closed-loop power control, the transmitting terminal can determine the transmission power based on the transmit power control (TPC) command received from the receiving terminal.

[0143] Predicting the received signal strength at a receiving terminal can be difficult due to various factors, including multipath fading channels, interference, etc. Therefore, the receiving terminal can adjust the received power level (e.g., received power range) by performing an automatic gain control (AGC) operation to prevent quantization errors of the received signal and maintain an appropriate received power. In a communication system, the terminal can perform the AGC operation using a reference signal received from a base station. However, in sidelink communication (e.g., V2X communication), the reference signal may not be transmitted from the base station. In other words, communication between terminals can be performed without a base station in sidelink communication. Therefore, performing the AGC operation in sidelink communication can be difficult. In sidelink communication, the transmitting terminal can first transmit a signal (e.g., a reference signal) to the receiving terminal before transmitting data, and the receiving terminal can adjust the received power range (e.g., received power level) by performing an AGC operation based on the signal received from the transmitting terminal. Thereafter, the transmitting terminal can transmit sidelink data to the receiving terminal. The signal used for AGC operation may be a duplicated signal for a signal to be transmitted later or a signal preset between terminals.

[0144] The time interval required for AGC operation may be 15 μs. When the subcarrier spacing in an NR system is 15 kHz, the time interval (e.g., length) of one symbol (e.g., OFDM symbol) may be 66.7 μs. When the subcarrier spacing in an NR system is 30 kHz, the time interval of one symbol (e.g., OFDM symbol) may be 33.3 μs. In the embodiments below, a symbol may mean an OFDM symbol. In other words, the time interval of one symbol may be more than twice the time interval required for AGC operation.

[0145] For sidelink communication, transmission of a data channel for data transmission and a control channel containing scheduling information for data resource allocation may be required. In sidelink communication, the data channel may be a Physical Sidelink Shared Channel (PSSCH), and the control channel may be a Physical Sidelink Control Channel (PSCCH). The data channel and the control channel may be multiplexed in a resource domain (e.g., time and frequency resource domain).

[0146] FIG. 12 is a conceptual diagram illustrating embodiments of a method for multiplexing a control channel and a data channel in sidelink communication.

[0147] Referring to FIG. 12, sidelink communication can support Option 1A, Option 1B, Option 2, and Option 3. If Option 1A and / or Option 1B are supported, control channels and data channels can be multiplexed in the time domain. If Option 2 is supported, control channels and data channels can be multiplexed in the frequency domain. If Option 3 is supported, control channels and data channels can be multiplexed in the time and frequency domains. Sidelink communication can natively support Option 3.

[0148] In sidelink communications (e.g., NR-V2X sidelink communications), a basic unit of resource configuration may be a subchannel. A subchannel may be defined by time and frequency resources. For example, a subchannel may be composed of multiple symbols (e.g., OFDM symbols) in the time domain and multiple resource blocks (RBs) in the frequency domain. A subchannel may be referred to as an RB set. Within a subchannel, data channels and control channels may be multiplexed based on Option 3.

[0149] In sidelink communication (e.g., NR-V2X sidelink communication), transmission resources can be allocated based on Mode 1 or Mode 2. When Mode 1 is used, a base station can allocate sidelink resources for data transmission to a transmitting terminal within a resource pool, and the transmitting terminal can transmit data to a receiving terminal using the sidelink resources allocated by the base station. Here, the transmitting terminal may be a terminal that transmits data in sidelink communication, and the receiving terminal may be a terminal that receives data in sidelink communication.

[0150] When Mode 2 is used, a transmitting terminal can autonomously select sidelink resources to be used for data transmission by performing a resource sensing operation (e.g., a resource sensing procedure) and / or a resource selection operation (e.g., a resource selection procedure) within a resource pool. The base station can configure a resource pool for Mode 1 and a resource pool for Mode 2 to the terminal(s). The resource pool for Mode 1 can be configured independently from the resource pool for Mode 2. Alternatively, a common resource pool can be configured for Mode 1 and Mode 2.

[0151] When Mode 1 is used, the base station can schedule resources used for sidelink data transmission to a transmitting terminal, and the transmitting terminal can transmit sidelink data to a receiving terminal using the resources scheduled by the base station. Therefore, resource collisions between terminals can be prevented. When Mode 2 is used, the transmitting terminal can select any resource by performing a resource sensing operation and / or a resource selection operation, and can transmit sidelink data using any selected resource. Since the above-described procedure is performed based on the individual resource sensing operation and / or resource selection operation of each transmitting terminal, collisions between the selected resources may occur.

[0152] Figure 13 is a conceptual diagram illustrating a first embodiment of a resource selection operation.

[0153] Referring to FIG. 13, a terminal (e.g., a transmitting terminal) can perform a resource sensing operation within a sensing window, and can perform a resource selection operation on sensed resource(s) (e.g., candidate resource(s)) within a selection window. When the resource selection operation is triggered at n, the terminal can select suitable resource(s) within the selection window (e.g., an interval from n+T1 to n+T2) based on the sensing result (e.g., resource(s) sensed by the resource sensing operation) within the sensing window (e.g., an interval from n-T0 to n-Tproc,0).

[0154] Based on the results of the resource sensing operation, the terminal can exclude candidate resource(s) that do not satisfy the conditions within the selection window. In other words, the terminal can determine the remaining candidate resources by excluding unsuitable candidate resource(s) from the entire candidate resources. If the ratio of the remaining candidate resources among the entire resources within the selection window is less than a reference ratio, the terminal can relax the conditions for excluding the candidate resource(s). For example, the terminal can increase the RSRP (reference signal received power) threshold, which is a condition for excluding the candidate resource(s), by 3 dB. Thereafter, the terminal can perform the resource selection operation again. The reference ratio can be preset to one of 20%, 35%, or 50% depending on the priority. If the ratio of the remaining candidate resources is greater than or equal to the reference ratio, the terminal can randomly select the final resource(s) to be used for SL transmission from among the remaining candidate resources. The terminal can perform SL transmission using the final resource(s).

[0155] Figure 14 is a conceptual diagram illustrating a first embodiment of a resource re-selection operation.

[0156] Referring to FIG. 14, the terminal may perform a resource re-selection operation after the resource selection operation, taking into account aperiodic data transmission, etc. The terminal may perform a resource re-selection operation by additionally considering the sensing results before the actual SL transmission (m-T3) after performing the operations illustrated in FIG. 13. The resource re-selection operation may be performed within a re-selection window. The terminal may further determine the suitability of the resource(s) reserved in m. If the resource(s) reserved in m are determined to be suitable, the terminal may perform SL transmission using the reserved resource(s). If the resource(s) reserved in m are determined to be unsuitable, the terminal may re-select the resource(s) for SL transmission and perform SL transmission using the re-selected resource(s).

[0157] In case an independent SL carrier is not set in SL communication, some of the UL resources may be set as SL resources by the SL resource pool setting procedure. A bitmap may be repeatedly applied to the remaining slot(s) except for the slot(s) in which at least X UL symbols are not set among the slots in a specific period and the slot(s) in which S(sidelink)-SSB is transmitted. X may be a natural number. The bitmap may indicate the slot(s) used as the SL resource. For example, the slot(s) corresponding to the bit(s) set to 1 among the bits in the bitmap may be used as the SL resource.

[0158] "When 15kHz SCS (subcarrier spacing) is applied and X or more UL symbols are configured in all slots" can be assumed. "When there are 10240 available slots in the DFN (direct frame number), the transmission period of S-SSB is 160ms, and there are 2 slots used for S-SSB transmission in each transmission period of S-SSB", the number of slots used for S-SSB transmission in the DFN can be 128. The bitmap for configuring SL time resources can include 10 bits. When the bitmap (e.g., a bitmap including 10 bits) is repeatedly applied to the remaining 10112 slots excluding the 128 slots used for S-SSB transmission out of the 10240 slots, there can exist 2 slots (e.g., reserved slots) to which the bitmap is not applied. Excluding the 2 reserved slots may be necessary. After excluding two spare slots from the 10112 slots, 10110 slots can remain. The above bitmap (e.g., a bitmap containing 10 bits) can be repeatedly applied to the 10110 slots 1011 times. "If the bitmap is 1111000000, and the slot corresponding to the bit set to 1 is used as an SL resource," 4044 slots within the DFN can be set as SL resources. In other words, among the 10240 slots, 4044 slots can be used for SL communication by configuring the SL resource pool.

[0159] A sidelink communication system supporting Rel-16 can be designed for terminals that do not have significant battery capacity constraints (e.g., terminals mounted on automobiles, V-UEs (vehicle UEs)). Therefore, power saving issues may not be significantly considered in resource sensing / selection operations of the terminals. In a sidelink communication system supporting Rel-17, power saving methods will be needed for sidelink communication with terminals that have battery capacity constraints (e.g., terminals carried by pedestrians, terminals mounted on bicycles, terminals mounted on motorcycles, pedestrian UEs (P-UEs). In the present disclosure, a V-UE may refer to a terminal that does not have significant battery capacity constraints, a P-UE may refer to a terminal that has battery capacity constraints, and a "resource sensing / selection operation" may include a "resource sensing operation and / or a resource selection operation." The resource sensing operation may refer to a partial sensing operation or a full sensing operation. The resource selection operation may refer to a random selection operation. Additionally, in the present disclosure, “operation of the terminal” may be interpreted as “operation of the V-UE” and / or “operation of the P-UE.”

[0160] To save power in LTE V2X, partial sensing and / or random selection operations may be introduced. If partial sensing is supported, the terminal can perform resource sensing operations for a portion of the sensing window, rather than the entire window, and select resources based on the results of the partial sensing operations. This operation can reduce the terminal's power consumption.

[0161] In Rel-14 LTE V2X, only periodic data transmission and reception operations may be possible. In Rel-14 LTE V2X, a terminal may randomly select candidate slots considering a preset minimum number in a resource selection period (e.g., a selection window), and perform a partial sensing operation considering a period of k×100 ms. k may be signaled by a bitmap (e.g., a bitmap including 10 bits). k may be determined based on the position of the bitmap (e.g., a bit included in the bitmap). For example, the 10 bits included in the bitmap may correspond to 1 to 10 from the MSB, and the period may be determined based on the value corresponding to the bit set to 1. The value corresponding to the bit set to 1 may be k.

[0162] If the MSB in the bitmap is set to 1, k may be 1. In this case, the terminal may perform a partial sensing operation considering a 100ms (=1×100ms) period. If the bit following the MSB in the bitmap is set to 1, k may be 2. In this case, the terminal may perform a partial sensing operation considering a 200ms (=2×100ms) period. If the LSB in the bitmap is set to 1, k may be 10. In this case, the terminal may perform a partial sensing operation considering a 1000ms (=10×100ms) period.

[0163] In Rel-14 LTE V2X, the period (e.g., the period of partial sensing operation) can be set to 20ms or 50ms. The 20ms period or 50ms period may not be supported in the resource pool for P-UE. In addition to the periods {0, 100ms, 200ms, ... , 1000ms}, a shorter period may also be supported in the NR communication system. The short period may be {1ms, 2ms, ... , 99ms}. Up to 16 periods can be selected from the resource pool, and the selected periods can be preset in the terminal. The terminal can perform the resource sensing operation and / or the resource (re)selection operation using one or more of the configured periods. If the random selection operation is supported, the terminal can randomly select a resource without performing the resource sensing operation. Alternatively, the random selection operation can be performed together with the resource sensing operation. For example, a terminal can determine a resource by performing a resource sensing operation, and select a resource(s) by performing a random selection operation within the determined resources.

[0164] In LTE V2X supporting Rel-14, resource pools capable of performing partial sensing operations and / or random selection operations can be configured independently from resource pools capable of performing full sensing operations. Resource pools capable of performing random selection operations, resource pools capable of performing partial sensing operations, and resource pools capable of performing both random selection operations and partial sensing operations can be configured independently. In other words, a random selection operation, a partial sensing operation, or "both random selection operations and partial sensing operations" can be configured in each resource pool. When both the random selection operation and the partial sensing operation are configured in a resource pool, a terminal can select one operation from the random selection operation and the partial sensing operation, select a resource by performing the selected operation, and perform sidelink communication using the selected resource.

[0165] In LTE V2X supporting Rel-14, SL data can be transmitted periodically based on a broadcast method. In an NR communication system, SL data can be transmitted based on at least one of a broadcast method, a multicast method, a groupcast method, and a unicast method. In addition, in an NR communication system, SL data can be transmitted periodically or aperiodically. A transmitting terminal can transmit SL data to a receiving terminal, and the receiving terminal can transmit HARQ-ACK feedback (e.g., ACK or NACK) for the SL data to the transmitting terminal via a PSFCH. In the present disclosure, a transmitting terminal may refer to a terminal that transmits SL data, and a receiving terminal may refer to a terminal that receives the SL data.

[0166] A terminal with reduced capability (hereinafter referred to as a "RedCap terminal") may operate in a specific usage environment. The capability of a RedCap terminal may be lower than that of a new radio (NR) normal terminal, and may be higher than that of an LTE-MTC (machine type communication) terminal, an NB (narrow band)-IoT (internet of things) terminal, and an LPWA (Low Power Wide Area) terminal, respectively. For example, there may be a terminal requiring "high data rate and low latency conditions" (e.g., a surveillance camera) and / or a terminal requiring "low data rate, high latency conditions, and high reliability" (e.g., a wearable device). To support the above-mentioned terminals, the maximum carrier bandwidth in FR1 may be reduced from 100 MHz to 20 MHz, and in FR2, the maximum carrier bandwidth may be reduced from 400 MHz to 100 MHz. The number of receive antennas in a RedCap terminal may be smaller than that of a typical NR terminal. When the carrier bandwidth and number of receive antennas are reduced, the reception performance of the RedCap terminal may be reduced, and thus the coverage of the RedCap terminal may be reduced.

[0167] Communication systems (e.g., NR systems) may operate at frequencies higher than the 52.6 GHz frequency band. As the frequency band in which the communication system operates increases, frequency offset error and phase noise may increase. For robust operation in such environments, the use of large SCS may be required. In the FR2 band, 60 kHz SCS and / or 120 kHz SCS may be supported, and additionally, 480 kHz SCS and / or 960 kHz SCS may be supported. In addition, "physical layer signal and channel design" and "physical layer procedures" may be required according to the new SCS. With regard to the initial access procedure, 120 kHz SSB and / or 240 kHz SSB may be supported in the FR2 band, and additionally, 480 kHz SSB and / or 960 kHz SSB may be supported. Here, 120kHz SSB may refer to SSB transmitted in a radio resource to which 120kHz SCS is applied, and 240kHz SSB may refer to SSB transmitted in a radio resource to which 240kHz SCS is applied. To support new SCS, an "initial BWP setup method" and an "SSB burst aggregation pattern" may be required.

[0168]

[0169] In Rel-18, the beginning of 5G-Advanced, research on network energy saving (NES) was conducted, and standardization work is in progress based on the results of this research. Research on NES discussed various technologies to reduce network energy consumption, including technologies in the time domain, frequency domain, spatial domain, and power domain. In the time domain, support for SSB-less SCell (secondary cell) operation and cell discontinuous transmission (DTX) / discontinuous reception (DRX) operation was standardized.

[0170] NES-related features are continuously being improved in Rel-19, and on-demand SSB and system information transmission are among the key candidate technologies in the time domain for NES. Therefore, this disclosure proposes an on-demand SSB and system information transmission method for NES.

[0171] Figure 15 is a conceptual diagram illustrating a scenario to which embodiments of the present invention can be applied.

[0172] Referring to FIG. 15, when a large amount of downlink data needs to be transmitted to a terminal connected to a PCell (primary cell), when a terminal requests resources for a large amount of uplink transmission, or when other requirements arise, it may be necessary to set up an additional SCell (secondary cell) through the CA (carrier aggregation) function.

[0173] At this time, a cell prior to being configured as an SCell by the PCell for a UE may exist as one of the neighboring cells. If no UE is connected to the cell, SSB transmission may not occur or may be transmitted at long intervals to conserve network energy. However, after the cell is configured as an SCell by the PCell or at the UE's request, on-demand SSB transmission may be required for UE synchronization and connection.

[0174] Meanwhile, in a CA environment, PCell and SCell can cooperate through separate interfaces, and terminals can access both PCell and SCell simultaneously.

[0175]

[0176] [Setting up on-demand SSB]

[0177] After a specific cell is configured as a SCell for a specific UE, on-demand SSB transmission may be required on the SCell either immediately after the specific cell is configured as an SCell or after the SCell is activated. More specifically, when a specific cell, previously a neighboring cell of the UE, is configured as an SCell by the PCell, on-demand SSB transmission-related information (or on-demand SSB transmission configuration information) may be configured and transmitted to the UE. Thereafter, the SCell can perform on-demand SSB transmission based on this information.

[0178] Alternatively, a specific cell may be configured as a SCell by a PCell while it is a neighboring cell of a UE, and then upon activation of the SCell, the SCell may initiate on-demand SSB transmission. In this case, on-demand SSB transmission-related information (or on-demand SSB transmission configuration information) may be transmitted to the UE when the SCell is configured. Alternatively, the on-demand SSB transmission-related information may be configured when the SCell is activated and transmitted to the UE along with an SCell activation command. The on-demand SSB transmission-related information may be transmitted to the UE via system information, UE-specific RRC signaling, MAC control element (CE), or downlink control information (DCI).

[0179] On-demand SSB transmission-related information can be determined by the PCell and transmitted to the UE and SCell, or determined by the SCell and transmitted to the UE via the PCell. Alternatively, on-demand SSB transmission-related information can be predefined by technical specifications. When on-demand SSB transmission-related information is determined by the PCell or SCell, it can be determined based on a request or report from the UE. Additionally or alternatively, on-demand SSB transmission-related information can also be determined based on the implementation method of the PCell or SCell.

[0180] In this case, the on-demand SSB transmission related information may include at least one of a cell ID, on-demand SSB numerology information, on-demand SSB transmission periodicity information, on-demand SSB transmission time and frequency information, or on-demand SSB transmission position information.

[0181] The SSB transmission period information may include one or more periodic values. The SSB transmission time information may be composed of one or more combinations of an SSB transmission start time, an SSB transmission end time, an SSB transmission duration, or the number of SSB burst sets. More specifically, the SSB transmission time information may be composed of a combination of an SSB transmission start time and an SSB transmission end time, a combination of an SSB transmission start time and an SSB transmission duration, or a combination of an SSB transmission start time and an SSB burst set. Alternatively, the SSB transmission time information may be composed of only an SSB transmission start time, an SSB transmission end time, or the number of SSB burst sets.

[0182] The SSB transmission start time and the SSB transmission end time may indicate when the on-demand SSB transmission actually starts and when the on-demand SSB transmission ends, respectively. The SSB transmission start time and the SSB transmission end time may be signaled by a combination of a radio frame, a half radio frame, a subframe, a slot, and / or an OFDM symbol index. Alternatively, the on-demand SSB transmission start time may be signaled by an offset value from the time when on-demand SSB transmission related information is received or the time when indication information for the on-demand SSB transmission is received, and the on-demand SSB transmission end time may be signaled by an offset value from the on-demand SSB transmission start time.

[0183] Alternatively, the start time of on-demand SSB transmission can be signaled by an offset value from a specific reference time. The offset value can be expressed in units of radio frames, half radio frames, subframes, slots, and / or OFDM symbols. The specific reference time can be set to the time at which on-demand SSB transmission-related information is transmitted. Alternatively, the specific reference time can be set based on the on-demand SSB transmission cycle.

[0184] More specifically, if a specific reference point is set based on an on-demand SSB transmission cycle, it can be set through a modulo operation between the radio frame number (or SFN index) and the on-demand SSB transmission cycle. For example, the specific reference point can be set based on the following mathematical expression 1.

[0185]

[0186]

[0187] Alternatively, the start time of the on-demand SSB transmission may be signaled as an offset value from the transmission time of the existing SSB. In this case, the offset value is preferably set based on the existing SSB transmission period and the on-demand SSB transmission period. More specifically, if the on-demand SSB transmission period is smaller than the existing SSB transmission period, the on-demand SSB transmission period is preferably set to a divisor of the existing SSB transmission period. For example, if the existing SSB transmission period is 40 ms, the on-demand SSB transmission period may be preferably set to one of the divisors of 40 ms, which are 5 ms, 10 ms, or 20 ms, which are divisors of 40 ms and are supported by the standard.

[0188] When set as described above, the transmission timing of the on-demand SSB can be set by applying an offset value based on the transmission timing of the existing SSB, and the offset value can use the on-demand SSB transmission cycle value as it is. It may be desirable to set the offset value so that the existing SSB burst and the on-demand SSB burst are evenly distributed considering the existing SSB transmission cycle. In other words, it may be desirable to set it so that the interval between SSB bursts, including the existing SSB bursts and the on-demand SSB bursts, is maintained constant.

[0189] Alternatively, if the transmission period of the on-demand SSB is shorter than that of the existing SSB, it may be desirable to set an offset value so that the on-demand SSB transmission timing does not overlap with the existing SSB transmission timing. More specifically, it is desirable to set the offset value to one of the values ​​smaller than the on-demand SSB transmission timing. For example, if the on-demand SSB transmission timing is 5 ms, the offset value is preferably set to one of 1 ms, 2 ms, 3 ms, or 4 ms.

[0190] In the above-described embodiment, if the offset value is not separately signaled, the terminal may assume that the offset value is '0'. In this case, the terminal may assume that the transmission of the on-demand SSB burst begins based on a specific reference time or the same radio frame as the existing SSB transmission time.

[0191] The half radio frame indication can indicate whether an on-demand SSB burst exists in the first 5ms or the last 5ms of a 10ms long radio frame. If the half radio frame indication is not separately signaled, the terminal can assume that the half radio frame indication is '0' and the on-demand SSB burst is transmitted in the first 5ms of the radio frame.

[0192] For SSB transmission duration, it may refer to a certain time period from the start of on-demand SSB transmission during which on-demand SSB(s) are transmitted. In this case, the time period may be expressed in terms of the number of slots, the number of subframes, the number of radio frames, or an absolute time unit (e.g., ms).

[0193] When there are multiple frequency locations where SSB transmission is possible, SSB transmission frequency information may include information about the location where the on-demand SSB is actually transmitted. More specifically, the information may be information about the SSB sync raster or information about the absolute radio frequency channel number (ARFCN). An SSB other than a cell-defining SSB (hereinafter CD-SSB) for initial access (i.e., a non-cell-defining SSB (hereinafter NCD-SSB)) may be transmitted at a frequency location corresponding to a specific ARFCN value other than the SSB sync raster. Furthermore, an NCD-SSB may be transmitted in the sync raster, but the SSB may not have an associated system information block 1 (SIB1) transmission.

[0194] SSB transmission position information may be information about the location where an on-demand SSB is actually transmitted within a radio frame, half-radio frame, subframe, slot, etc., within an on-demand SSB transmission interval. This information may be in the form of a bitmap of all candidate SSB locations, or in compressed form.

[0195] Through SSB transmission location information, information indicating a new pattern different from the existing SSB transmission pattern, a pattern identical to the existing SSB transmission pattern, or one of the existing SSB transmission patterns, if there are multiple existing SSB transmission patterns, can be transmitted. If an on-demand SSB transmission pattern identical to the existing SSB transmission pattern is used, the location of the on-demand SSB(s) actually transmitted within the on-demand SSB burst can be the same as the location where the existing SSB(s) are transmitted. If an on-demand SSB transmission pattern different from the existing SSB transmission pattern is used, the on-demand SSB(s) can be transmitted at some of the location(s) where the existing SSB(s) are transmitted, or can be transmitted at a location(s) different from the location(s) where the existing SSB(s) are transmitted. If SSB transmission location information is not signaled, the existing always-on SSB transmission pattern or the SSB transmission pattern of the PCell can be used as the on-demand SSB transmission pattern.

[0196]

[0197] Information related to on-demand SSB transmission can be configured separately from the SSB configuration information within the existing SCell configuration information.

[0198] If an always-on SSB exists within the SCell, the SSB can be transmitted based on the SSB configuration information within the existing SCell configuration information. In this case, additional on-demand SSBs can be transmitted based on separate configuration information. Conversely, if an always-on SSB does not exist within the SCell, the SSB configuration information within the existing SCell configuration information can be used to configure the on-demand SSB.

[0199] Meanwhile, if the on-demand SSB configuration information exists separately, the SSB configuration information in the existing SCell configuration information may be implicitly ignored. Alternatively, if the on-demand SSB configuration information exists separately, there may be explicit signaling to indicate that the SSB configuration information in the existing SCell configuration information be ignored. For example, if the SSB burst period value in the SSB configuration information in the existing SCell configuration information indicates a specific value (e.g., 0 ms), the SSB configuration information in the existing SCell configuration information may be ignored and the on-demand SSB may be transmitted according to the on-demand SSB configuration information. That is, since 0 ms is not defined for the SSB burst period information in the existing SCell configuration information, the spare2 or spare1 value that is not yet used may be defined as 0 ms. In addition to the SSB burst period parameter, other parameter(s) may also be used for the same purpose. For example, if all bits in the bitmap indicating the SSBs actually transmitted in the SSB burst are set to '0', the SSB configuration information in the existing SCell configuration information may be ignored.

[0200] Alternatively, a 1-bit instruction bit indicating enable / disable of the existing SSB configuration information may be added to the existing SCell configuration information. More specifically, if the instruction bit is set to '0', the existing SSB configuration information is ignored (i.e., disabled) and it may be determined that there is no SSB that is always transmitted. If the instruction bit is set to '1', it may be determined that the existing SSB configuration information is enabled and there is an SSB that is always transmitted. The instruction bit may be additionally set only when there is separate on-demand SSB configuration information.

[0201] When additional on-demand SSB configuration information is configured in a situation where SSB configuration information exists in the existing SCell configuration information, some of the on-demand configuration information may use some of the existing SSB configuration information as is. More specifically, if parameters such as SSB location information actually transmitted within an SSB burst, frequency location information, SSB subcarrier spacing information, cell ID information, and SSB transmission power information use the same values ​​as the parameters included in the existing SSB configuration information, they may not be included in the on-demand SSB configuration information.

[0202]

[0203] [Transmission of SSB on demand]

[0204] As described above, on-demand SSB transmission of SCell can be applied in various ways in the process of setting a specific cell among several neighbor cells as an SCell for a terminal and activating the SCell to operate it as an SCell.

[0205] Figure 16 is a timing diagram for explaining the setup and activation of SCell and the transmission timing of on-demand SSB.

[0206] Referring to Fig. 16, in a state where a specific cell exists as a neighboring cell of a terminal (phase 0), on-demand SSB transmission may not be necessary in the cell because actual data transmission does not occur in the cell. However, in a state where a specific cell is configured as a SCell of a terminal (phase 1), the cell may be activated thereafter and actual data transmission may be performed in the cell. In order to activate a specific SCell among multiple SCells, continuous cell monitoring, such as RSRP (reference signal received power) measurement using SSB, may be required. Therefore, on-demand SSB transmission may be required from the time it is configured as a SCell. In this case, the terminal may determine whether to transmit on-demand SSB based on whether SCell configuration information or on-demand SSB transmission-related information is received. Alternatively, a separate indication indicating whether to transmit on-demand SSB may be transmitted to the terminal.

[0207] For example, the UE can determine whether on-demand SSB transmission is performed on a specific SCell based on the received SCell configuration information or on-demand SSB transmission related information. More specifically, if the UE receives on-demand SSB transmission related information (i.e., on-demand SSB transmission configuration information) for a specific SCell, the UE can determine that on-demand SSB transmission is performed on the SCell, and can perform on-demand SSB reception based on the transmitted configuration information. In this case, if there is no separate indication indicating whether on-demand SSB transmission is started, the time point at which on-demand SSB transmission is started may vary depending on whether the configuration information is received through DCI, MAC CE, or RRC signaling. The UE can determine that SSB transmission is started from the earliest available on-demand SSB transmission time point after a certain amount of time for processing each signaling has elapsed since the information was received.

[0208] The above-described method can also be applied to cases where a terminal determines whether to perform on-demand SSB transmission based on SCell configuration information. That is, if the SCell configuration information includes configuration information for on-demand SSB transmission, the terminal can determine that SSB transmission begins from the earliest available on-demand SSB transmission time point after a certain amount of time for signaling-specific processing has elapsed since the SCell configuration information was received.

[0209] Meanwhile, when SCells are configured, SCell activation or deactivation can be determined not only through SSB measurements, but also through various methods, such as terminal position and terminal triggers. Therefore, to maximize network energy savings, on-demand SSB transmission may not be performed during the SCell-configured phase (i.e., phase 1).

[0210] In such cases, it may be desirable to perform on-demand SSB transmission in the phase (phase 2) in which the SCell is activated after the SCell is configured. Generally, since the SCell is activated to perform data transmission or reception, on-demand SSB transmission may be required for determining the UE's transmission / reception beam and appropriate scheduling based on channel status information. In this case, whether on-demand SSB transmission is performed can be confirmed through a separate indicator transmitted via PDCCH, SCell activation / deactivation information transmitted via RRC signaling or MAC CE signaling, or whether configuration information for on-demand SSB transmission is transmitted.

[0211] For example, whether on-demand SSB transmission is performed on a specific SCell may be indicated by utilizing a bit indication in DCI transmitted via a specific PDCCH format (e.g., format 2_X). More specifically, a bit corresponding to an SCell on which on-demand SSB transmission is performed may be set to '1' in a bitmap corresponding to an SCell group, and a bit corresponding to an SCell on which on-demand SSB transmission is not performed may be set to '0'. Information related to the mapping of bits corresponding to specific SCells in the bitmap may be set in advance via system information or UE-specific RRC signaling.

[0212] In this case, different PDCCH formats can be configured for each SCell group. Alternatively, even if the same PDCCH format is used for all SCell groups, the SCell groups can be distinguished by applying different radio network temporary identifiers (RNTIs) or different PDCCH monitoring occasions (e.g., different search space sets).

[0213] Alternatively, bitmaps for multiple SCell groups can be configured within a single PDCCH. In this case, information regarding the bitmap corresponding to a specific SCell group among the multiple bitmaps and the mapping of bits corresponding to a specific SCell within the bitmap can be configured in advance through system information or UE-specific RRC signaling. Alternatively, the index or cell ID information of the SCell where the on-demand SSB is transmitted can be included within the DCI. Such a PDCCH can be applied to both a common PDCCH and a UE-specific PDCCH.

[0214] When an indication is given on whether to transmit on-demand SSB through a common PDCCH, a hybrid automatic repeat request (HARQ)-acknowledgment (ACK) feedback may be transmitted separately to confirm reception of the corresponding PDCCH. At this time, uplink resources for HARQ-ACK feedback may be configured in advance through system information, terminal-specific RRC signaling, or DCI signaling through the corresponding PDCCH. Since the common PDCCH can be received by multiple terminals simultaneously, if an uplink resource for HARQ-ACK feedback is configured singly, it may be unclear whether a specific terminal should use the resource. Furthermore, if multiple terminals use the same resource, it may be impossible to confirm whether a specific terminal has received the PDCCH. Therefore, when an indication is given on whether to transmit on-demand SSB through a common PDCCH, it may be desirable to configure an uplink resource for HARQ-ACK feedback individually for each terminal, and this can be configured through terminal-specific RRC signaling.

[0215] When on-demand SSB transmission is indicated through a UE-specific PDCCH (e.g., SCell index or cell ID and a 1-bit indication), whether or not to transmit SSB on demand can be confirmed by utilizing whether HARQ-ACK feedback is transmitted for scheduled downlink data reception or uplink data transmission through the corresponding PDCCH. More specifically, when on-demand SSB transmission is indicated through a PDCCH for downlink data scheduling, the UE can transmit HARQ-ACK feedback depending on whether reception of scheduled data through the corresponding PDCCH is successful, and the base station can confirm whether or not to receive the PDCCH by receiving the feedback. At this time, regardless of whether the HARQ-ACK feedback is an ACK (positive acknowledgment) or NACK (negative acknowledgment), if HARQ-ACK feedback is transmitted, it can be determined that the PDCCH has been normally received.

[0216] When an instruction on whether to transmit on-demand SSB is received through a PDCCH for uplink data scheduling, the UE performs the scheduled uplink transmission through the corresponding PDCCH, and the base station can confirm whether the PDCCH has been received by receiving it. However, even if the UE successfully receives the PDCCH, it may not be able to perform the scheduled uplink transmission through the corresponding PDCCH due to issues such as priority or scheduling resource allocation. In this case, the base station cannot confirm whether the PDCCH has been received and may retransmit the on-demand SSB transmission instruction later. To prevent this, when an instruction on whether to transmit on-demand SSB is received through a PDCCH for uplink scheduling, a HARQ-ACK feedback may be separately transmitted to confirm whether the PDCCH has been received, similar to the case where the PDCCH has been received. The HARQ-ACK feedback resource for this purpose may be configured through system information, UE-specific RRC signaling, or DCI signaling through the corresponding PDCCH.

[0217] When indicating whether to transmit on-demand SSB bursts via DCI, in addition to the information about the corresponding cell described above, additional information may be transmitted together. For example, if a specific number of on-demand SSB bursts are transmitted among a plurality of preset on-demand SSB bursts, information about the specific number may be included in the DCI. Alternatively, index information corresponding to the specific number may be included in the DCI. Furthermore, if multiple on-demand SSB burst transmission cycle values ​​are preset, information about a specific transmission cycle or index information corresponding to a specific transmission cycle may be included in the DCI.

[0218] On-demand SSB transmission may also be indicated by transmitting SCell activation / deactivation information via MAC CE. If activation of specific SCell(s) is indicated via MAC CE, the UE may determine that on-demand SSB transmission is to be performed on the corresponding SCell. More specifically, if the UE receives SCell activation information via MAC CE, the UE may determine that the specific SCell(s) will be activated and on-demand SSB transmission will be performed after a specific time when the information in the MAC CE is applied based on the information, and may perform reception of the on-demand SSB. Alternatively, information indicating whether to perform on-demand SSB transmission may be transmitted via MAC CE separately from the SCell activation / deactivation information. In this case, the indication information may be transmitted together with the SCell activation / deactivation information, or may be transmitted via a separate MAC CE.

[0219] When information on whether to transmit on-demand SSB is transmitted together with SCell activation / deactivation information, a 1-bit indication may be included in addition to the activation / deactivation indicator for each SCell to indicate whether to transmit on-demand SSB for each SCell. In this case, if the SCell activation / deactivation information consists of N bits, it may be desirable for the information indicating whether to transmit on-demand SSB to also consist of N bits.

[0220] Even if information on whether to transmit on-demand SSB is transmitted through a separate MAC CE, if the MAC CE information for activating / deactivating SCell is composed of N bits, it may be desirable to also compose the information indicating whether to transmit on-demand SSB to each SCell with N bits to indicate whether to transmit on-demand SSB to each SCell.

[0221] Alternatively, if on-demand SSB transmission is indicated for a specific SCell by a MAC CE that includes an indicator indicating whether on-demand SSB transmission is performed, activation / deactivation information for the specific SCell may also be transmitted. Therefore, when on-demand SSB transmission for a specific SCell is indicated, whether the SCell is activated / deactivated may also be indicated. In this case, SCell activation / deactivation information for SCells that are not indicated to perform on-demand SSB transmission may be treated as invalid.

[0222] FIG. 17 is a conceptual diagram illustrating one embodiment of a MAC CE including an indicator indicating whether to transmit on-demand SSB and SCell activation / deactivation information.

[0223] Referring to FIG. 17, Octet 1 may be an indicator indicating whether on-demand SSB transmission is performed, and Octet 2 may be SCell activation / deactivation indication information. When O7, O5, and O4 indicate that on-demand SSB is transmitted in the corresponding cells (e.g., the corresponding information is set to '1'), only C7, C5, and C4, which are SCell activation / deactivation information for the corresponding cells, are valid and may indicate whether the corresponding SCell is activated or deactivated. In this case, information of C6, C3, C2, and C1 may be treated as invalid.

[0224] Additionally, on-demand SSB transmission may be indicated for some or all of the SCells activated through Oct 2. For example, if C7, C5, and C4 are set to '1' in Oct 2 and the corresponding SCells are activated, the corresponding C7, C5, and C4 in Oct 1 may also be set to '1' to indicate that on-demand SSB is transmitted. Alternatively, only some of C7, C5, and C4 in Oct 1 may be set to '1' to indicate that on-demand SSB is transmitted. For example, if only C7 and C4 are set to '1', the UE may determine that on-demand SSB is transmitted on the SCells corresponding to C7 and C4, but that the SCell corresponding to C5 is activated but on-demand SSB is not transmitted.

[0225] Alternatively, on-demand SSB transmission may be indicated via Oct 1 even though a specific SCell is not activated via Oct 2. For example, if C7, C5, and C4 are set to '1' in Oct 1 to indicate that on-demand SSB transmission will be indicated on those SCells, but only C7 and C4 are set to '1' in Oct 2, the UE may determine that the SCells corresponding to C7 and C4 are activated and that on-demand SSB transmission will also occur. On the other hand, the SCell corresponding to C5 may be determined to transmit on-demand SSB but not yet activated.

[0226] In the above embodiment, Oct 1 is an indicator indicating whether to transmit on-demand SSB, and Oct 2 is SCell activation / deactivation indication information. However, the same method can be applied to the case where Oct 1 indicates SCell activation / deactivation information and Oct 2 indicates whether to transmit on-demand SSB.

[0227] In addition, the above example describes a case where the SCell activation / deactivation information and the indicator indicating whether to transmit on-demand SSB are composed of 8 bits including one reserved bit, but the same method can be applied to a case where the indicator is composed of more bits.

[0228] As described above, when the indicator indicating whether to transmit on-demand SSB and the SCell activation / deactivation indication information are transmitted through separate MAC CEs, each MAC CE may be composed of only Oct 1 or Oct 2 of Fig. 17. At this time, it is preferable that the number of indicators indicating whether to transmit on-demand SSB in the corresponding MAC CE be set equal to the number of SCells indicated by the SCell activation / deactivation indication information.

[0229] Another way to indicate whether to transmit on-demand SSB via a separate MAC CE is to include an indicator indicating whether to transmit on-demand SSB for the SCell along with a specific SCell index or cell ID of the SCell in the MAC CE.

[0230] Alternatively, if only a specific SCell index or cell ID is transmitted in the MAC CE, it can be determined that on-demand SSB transmission is indicated for that SCell. This indication allows for individual indications of on-demand SSB transmission for specific SCells, without requiring a simultaneous indication of on-demand SSB transmission for all SCells.

[0231] When indicating whether to transmit on-demand SSB bursts through a separate MAC CE, in addition to the information about the corresponding cell described above, additional information may be transmitted together. For example, if a specific number of on-demand SSB bursts are transmitted among a plurality of preset on-demand SSB bursts, information about the specific number may be included in the MAC CE. Alternatively, index information corresponding to the specific number may be included. Furthermore, if multiple on-demand SSB burst transmission period values ​​are preset, information about a specific transmission period or index information corresponding to a specific transmission period may be included in the MAC CE.

[0232] Meanwhile, if there are multiple pieces of on-demand SSB configuration information for each SCell, multiple bitmaps indicating whether or not to transmit on-demand SSB can be set accordingly. For example, if there are N pieces of on-demand SSB configuration information for each SCell, the bitmaps indicating whether or not to transmit on-demand SSB as illustrated in Fig. 17 can also be set to N. This can be applied to both cases where the indicator indicating whether or not to transmit on-demand SSB is transmitted together with the SCell activation / deactivation indication information or where the indicator indicating whether or not to transmit on-demand SSB is transmitted separately.

[0233] On-demand SSB transmission can also be indicated via RRC signaling. SCell configuration information and SCell activation / deactivation information can be transmitted separately via RRC signaling, or both can be transmitted together.

[0234] When SCell configuration information and SCell activation / deactivation information are transmitted separately, an indicator indicating whether on-demand SSB transmission is to be performed may be additionally included in the SCell configuration information or SCell activation / deactivation information and transmitted. In this case, whether the indicator indicating whether on-demand SSB transmission is to be included in either the SCell configuration information or the SCell activation information may be configured differently depending on the on-demand SSB transmission start time desired by the base station. Alternatively, whether the indicator indicating whether on-demand SSB transmission is to be included in either the SCell configuration information or the SCell activation information may be configured in advance through system information or RRC signaling, or may be defined in advance by technical specifications.

[0235] When SCell configuration information and SCell activation / deactivation information are transmitted together, an indicator indicating whether or not to transmit on-demand SSB can be additionally included in the information. In this case, it is preferable to set the indicator indicating whether or not to transmit on-demand SSB to the same number of SCells, allowing for independent indication of whether or not to transmit on-demand SSB for each SCell. Therefore, an indication can be provided that on-demand SSB will be transmitted even when SCell configuration is complete but not yet activated for a specific SCell. Alternatively, an indication can be provided that on-demand SSB will be transmitted simultaneously with SCell activation for a specific SCell.

[0236] Alternatively, an indicator indicating whether on-demand SSB transmission is possible can be transmitted via RRC signaling, separate from SCell configuration information and SCell activation / deactivation information. In this case, the number of indicators indicating whether on-demand SSB transmission is possible is preferably set to be equal to the number of SCells, allowing each SCell to independently indicate whether on-demand SSB transmission is possible.

[0237] Alternatively, RRC signaling can be used to individually indicate whether to transmit on-demand SSB for a SCell, such as the SCell index or the cell ID of the SCell. In this case, on-demand SSB transmission can be individually indicated for a specific SCell without having to simultaneously indicate on-demand SSB transmission for all SCells. If on-demand SSB transmission is indicated through a separate RRC signaling, it can be transmitted separately from the transmission timing of SCell configuration information and SCell activation / deactivation information, allowing the base station to indicate on-demand SSB transmission at a desired time.

[0238] In addition to the SCell configuration information transmitted via RRC signaling, an indication (e.g., sCellState) indicating the activation state of the corresponding SCell may be included. Similarly, as another method for indicating whether on-demand SSB transmission is possible, the SCell configuration information may additionally include an indication indicating whether on-demand SSB transmission is possible on the corresponding SCell. At this time, it may be desirable to reuse parameters included in the existing SCell configuration information for parameters related to the on-demand SSB transmission of the corresponding SCell (physical cell ID (physCellId), subcarrier spacing (ssbSubcarrierSpacing), SSB transmission periodicity (ssb-periodicityServingCell), SSB information actually transmitted within an SSB burst (SSB positions in burst (ssb-PositionsInBurst), SSB transmission power (ss-PBCH-BlockPower), SSB transmission frequency position (SSB transmission frequency position (ARFCN-valueNR), etc.). Some parameters (e.g., ssb-periodicityServingCell) may have additional or changed values.

[0239] Additionally, SCell configuration information may further include information such as the system frame number (SFN) in which SSB transmission begins, the half radio frame indication (HRF), the time window in which on-demand SSB is transmitted, the number of on-demand SSB bursts, and the SFN offset.

[0240] Alternatively, the on-demand SSB transmission related parameters may be defined as a new, separate configuration and included in the SCell configuration information, along with an indicator indicating whether or not on-demand SSB transmission is performed. In this case, it is preferable to configure the parameters so that they can be distinguished from the SSB transmission related parameters of the existing SCell, and items having the same values ​​as the SSB transmission related parameters of the existing SCell (e.g., physCellId, ssbSubcarrierSpacing, etc.) may be omitted from the newly configured on-demand SSB transmission related parameter list.

[0241] Additionally, the SCell configuration information may explicitly include an indicator indicating whether the SCell supports on-demand SSB transmission, or it may be implicitly indicated by the presence or absence of an indicator indicating whether on-demand SSB transmission is supported.

[0242] In the above-described multiple embodiments, if the indicator indicating whether or not to transmit on-demand SSB is configured as a 1-bit indicator, if the bit is set to '1', it may indicate that on-demand SSB transmission is performed. On the other hand, if the bit is set to '0', if the on-demand SSB is not currently being transmitted, it may indicate that the on-demand SSB transmission has not yet started. If the on-demand SSB is currently being transmitted, it may indicate that the on-demand SSB transmission has been deactivated.

[0243] On-demand SSB transmission can be deactivated after a specific time interval or a specific number of SSB bursts for on-demand SSB transmission has been preset after transmission has been initiated by a transmission indicator, or after the specific time interval or the specific number of SSB bursts has been preset. If the specific time interval or the specific number of SSB bursts has not been preset, on-demand SSB transmission can be deactivated by the above-described indicator.

[0244] Additionally, even if an on-demand SSB transmission is in progress with a specific time interval or a specific number of SSB bursts preset for on-demand SSB transmission, the transmission can be stopped by an explicit indication to disable on-demand SSB transmission. If the terminal receives such an indication, it can determine that on-demand SSB transmission has been disabled.

[0245]

[0246] [Overlap between on-demand SSB and always-on SSB]

[0247] When a cell supporting on-demand SSB operation transmits periodic (always-on) legacy SSB, on-demand SSB transmission must be performed taking into account the periodic legacy SSB transmission. During on-demand SSB transmission based on the on-demand SSB configuration information, the transmission timing or frequency location of the on-demand SSB may overlap with the transmission timing or frequency location of the periodic legacy SSB. In this case, it is necessary to determine which of the two SSBs to transmit.

[0248] More specifically, if the transmission timing of an on-demand SSB burst overlaps with the transmission timing of a periodic SSB burst, and the frequency positions of the SSB bursts also overlap, the base station can select and transmit one of the two SSB bursts. For example, the on-demand SSB burst can be dropped and only the periodic SSB burst can be transmitted, or conversely, the periodic SSB burst can be dropped and only the on-demand SSB burst can be transmitted. Which SSB burst is to be transmitted can be determined by the technical specifications. Alternatively, which SSB burst is to be transmitted can be preset through system information, etc. In this case, it may be desirable to transmit the existing (always-on) SSB preferentially, taking into account the operation of the existing terminal.

[0249] If SSB bursts are transmitted at the same frequency location and only some of the SSBs within the SSB bursts overlap in transmission timing, the remaining non-overlapping SSBs can be transmitted as is according to the existing periodic pattern or on-demand SSB configuration. In this case, the union of the existing periodic (always-on) SSB burst transmission and the on-demand SSB burst transmission can have a periodic pattern or an aperiodic pattern. More specifically, if the existing periodic SSB burst transmission is performed with a period of 20 ms and the additional on-demand SSB burst transmission is also configured to have a period of 20 ms and an offset of 10 ms with respect to the existing periodic SSB burst transmission, the union of the two SSB burst transmissions (i.e., the always-on SSB burst and the on-demand SSB burst) can have a periodic SSB transmission pattern with a period of 10 ms. Alternatively, when the existing periodic SSB burst transmission is performed with a 20ms period, if the additional on-demand SSB burst transmission is set to have a 10ms period and a 0ms offset with respect to the existing periodic SSB burst transmission, the sum of the two SSB burst transmissions may overlap every 20ms. However, as described above, if one of the two SSB bursts is dropped, the sum of the two SSB burst transmissions may ultimately have a periodic SSB transmission pattern with a 10ms period. However, if the periods of the two SSB bursts are different or an appropriate offset value that ensures the periodicity of the two SSB bursts is not set, the sum of the two SSB burst transmissions may have an aperiodic pattern.Even if the sum of two SSB burst transmissions is periodic or aperiodic, in order to reduce the complexity of receiving two SSB bursts by a terminal, it is desirable that the PBCH payloads of SSBs having the same SSB index among the SSBs transmitted within the two SSB bursts have the same values ​​except for some parameters (e.g., SFN index, half-frame index, etc.).

[0250] Even if the transmission timings of an on-demand SSB burst and a periodic SSB burst overlap, if they are transmitted at different frequency locations, and if part of the frequency-axis resource regions of the two SSB burst sets overlap, only one of the two SSB bursts can be selected and transmitted as described above, and the two SSB bursts can be transmitted simultaneously as long as the frequency-axis resource regions of the two SSB burst sets do not overlap. If the existing transmitting SSB burst contains CD-SSB(s) and is transmitted in the synchronization raster, it is desirable for the on-demand SSB burst to be transmitted at a different frequency location to avoid the existing transmitting SSB burst, and the existing transmitting SSB burst and the on-demand SSB burst can be located in different BWPs within the same CC. However, in this case, since the SSB transmission overhead is large, if the transmission timings of the two SSB bursts overlap, only one of the two SSB bursts may be transmitted even if the frequency-axis resource regions do not overlap. In this case, which SSB burst will be transmitted can be determined by the technical specifications or can be preset through system information, etc.

[0251] Alternatively, as described above, the transmission timings of the two SSB bursts may be preset so as not to overlap. That is, when setting on-demand SSB transmission-related information, an appropriate transmission timing of the on-demand SSB burst may be set so as not to overlap the transmission timings of the two SSB bursts by considering the previously transmitted periodic SSB transmissions. In this case as well, in order to reduce the complexity of the UE receiving the two SSB bursts, it is preferable that the PBCH payloads of the SSBs having the same SSB index among the SSBs transmitted within the two SSB bursts have the same values ​​except for some parameters (e.g., SFN index, half-frame index, etc.).

[0252]

[0253] [Determining the transmission time of on-demand SSB]

[0254] As described above, a terminal that determines whether to perform on-demand SSB transmission of specific SCell(s) through DCI transmitted through PDCCH or MAC CE and / or RRC signaling transmitted through PDSCH can perform on-demand SSB reception based on configuration information for on-demand SSB transmission that has been transmitted in advance.

[0255] As described above, when an SSB transmission instruction is explicitly or implicitly received along with separate signaling or configuration information, the actual SSB transmission time determined by the terminal may vary depending on whether the instruction is made through DCI, MAC CE, or RRC signaling.

[0256] First, if on-demand SSB transmission is explicitly or implicitly indicated through DCI, the terminal can determine that on-demand SSB transmission begins after a certain offset considering the terminal's processing time after receiving the DCI.

[0257] At this time, the offset value may be additionally signaled as a separate value through the corresponding DCI. Alternatively, a value predefined in the technical specification may be used as the offset value. Alternatively, one of multiple values ​​predefined in RRC signaling may be indicated as the offset value. Alternatively, the offset value may be predefined in the specification as a specific value according to the subcarrier spacing. If the offset value is set to one of multiple values, it may also be set based on the UE capability (terminal performance reporting information) reported in advance by the terminal.

[0258] The offset can be defined in milliseconds (ms) or in terms of the number of slots. If the offset is defined in terms of the number of slots, and the subcarrier spacing of the on-demand SSB differs from the subcarrier spacing of the DCI indicator, the offset value can be determined by considering the ratio between the two subcarrier spacings.

[0259] For example, if the subcarrier spacing of the DCI indicator is 15 kHz and the subcarrier spacing of the on-demand SSB is 30 kHz, and the offset is signaled or set to 3 slots, the terminal can determine the on-demand SSB transmission timing by applying an offset of 30 kHz / 15 kHz * 3 = 6 slots. Alternatively, the terminal can determine the offset based on the smaller or larger of the two subcarrier spacings. Alternatively, the terminal can determine the offset based on the smallest or largest value among the subcarrier spacings supported by the system. Alternatively, the specification may pre-define the terminal to determine the offset based on the subcarrier spacing in which the on-demand SSB indicator is transmitted or the subcarrier spacing of the on-demand SSB.

[0260]

[0261] When on-demand SSB transmission is explicitly or implicitly indicated through MAC CE, the terminal can determine that on-demand SSB is transmitted after a certain period of time has elapsed after receiving a PDSCH including the MAC CE or transmitting HARQ-ACK feedback regarding whether the PDSCH has been received.

[0262] More specifically, when a slot in which a PUCCH or PUSCH including ACK / NACK feedback information for a PDSCH including the corresponding MAC CE is transmitted is called slot k, it can be determined that an on-demand SSB is transmitted from a time point (slot(s) corresponding to 3 ms + X (slots)) elapsed from slot k (e.g., from the slot that first arrives after the time point). In terms of the elapsed time from a PDSCH transmission time point, when a slot in which a PDSCH including the corresponding MAC CE is received is called slot n, it can be determined that an on-demand SSB is transmitted from a time point (slot(s) corresponding to (time interval between slot k and slot n) + 3 ms + X slot(s)) elapsed from slot n (e.g., from the slot that first arrives after the time point). At this time, in order to determine the number of slots corresponding to a time duration of 3 ms, the subcarrier of the active UL BWP in which ACK / NACK feedback information is transmitted may be used as a reference. For example, the slots corresponding to a time duration of 3 ms may be determined as the minimum number of slots having a length of 3 ms or more. Alternatively, if expressed as the elapsed time from the time point of PDSCH reception regardless of whether ACK / NACK feedback information is transmitted, when the slot in which the PDSCH including the corresponding MAC CE is received is called slot n, it may be determined that the on-demand SSB is transmitted from the time point after (slot(s) corresponding to 3 ms + X slot(s)) has elapsed from slot n (e.g., from the slot that arrives first after that time point), and at this time, in order to determine the number of slots corresponding to a time duration of 3 ms, the subcarrier interval of the active DL BWP in which the corresponding PDSCH is received may be used as a reference. For example, the slots corresponding to a time length of 3ms can be determined as the minimum number of slots having a length of 3ms or more.

[0263] Here, X can be defined as the number of slots. Alternatively, X can be expressed in units of ms rather than the number of slots. X can be a value predefined in the technical specification, or can be set via RRC signaling or MAC CE. Alternatively, X can be set by setting multiple candidate values ​​via RRC signaling and then indicating one of them via MAC CE.

[0264] Additionally or alternatively, the X value may be set differently depending on the subcarrier spacing. For example, the X value may be set to a specific value based on the smallest subcarrier spacing and may be set to increase in proportion to the subcarrier spacing. If there is no specific value set based on the smallest subcarrier spacing, the value may be regarded as 0. If the subcarrier spacing of the PDSCH on which the MAC CE is transmitted and the subcarrier spacing on which the on-demand SSB is transmitted are different, the X value may be set considering the subcarrier spacing of the PDSCH. The specification may also pre-define the X value to be set based on the subcarrier spacing on which the MAC CE is transmitted or the subcarrier spacing on which the on-demand SSB is transmitted.

[0265] When on-demand SSB transmission is explicitly or implicitly indicated through RRC signaling, the on-demand SSB transmission timing may vary depending on whether there is an uplink response to it.

[0266] FIG. 18 is a timing diagram for explaining RRC processing delay according to embodiments of the present invention.

[0267] Referring to FIG. 18, when an uplink response to an RRC command is required, the time from the time the UE receives a PDSCH containing the RRC command to the time the UE receives a UL grant (resource allocation for uplink transmission) for transmitting an uplink response to the corresponding RRC command can be defined as the RRC processing delay. At this time, performance requirements for RRC processing delay according to various cases can be defined in units of ms in TS 38.331. Therefore, when on-demand SSB transmission is indicated through RRC signaling and an uplink response to the indication is required, an RRC processing delay value for this needs to be newly defined. The UE can determine that on-demand SSB is transmitted after the defined RRC processing delay has elapsed.

[0268] If the RRC signaling indicating whether to transmit on-demand SSB does not require an uplink response, a separate RRC processing delay may not be defined. This may make it difficult for the UE to determine the exact point in time when on-demand SSB transmission begins. In this case, the UE may determine that on-demand SSB transmission is occurring immediately after receiving the on-demand SSB transmission indication via RRC signaling. Alternatively, the UE may determine that on-demand SSB transmission is occurring after a specific period of time has elapsed since receiving the indication.

[0269] In this case, the specific time may be implemented by the terminal according to its processing capabilities, or a value predefined by technical specifications may be used. The specific time may be defined as the same value as the value set in the indicator transmission method via the aforementioned MAC CE, or as a different specific value. Alternatively, the specific time may be separately set via RRC signaling.

[0270] In addition, as methods for determining that on-demand SSB transmission is performed after the terminal receives the indicator, a method for determining that on-demand SSB transmission is started immediately after the specific time has elapsed, and a method for determining that on-demand SSB transmission is started at the earliest SSB transmission occasion after the specific time has elapsed may be used.

[0271] More specifically, in a method for determining that on-demand SSB transmission begins after a specific time has elapsed, the specific time may indicate a slot boundary at which on-demand SSB transmission begins or a symbol boundary at which on-demand SSB transmission begins. Accordingly, the specific time may be preset on a slot-by-slot basis or a symbol-by-symbol basis. In addition, if the numerology of a cell in which an on-demand SSB transmission instruction is transmitted differs from the numerology of a cell in which the actual on-demand SSB is transmitted, the specific time may be determined by considering the numerology ratio between the two cells.

[0272] For example, assuming that the subcarrier spacing of the cell where the on-demand SSB transmission instruction is transmitted is SCS#0 and the subcarrier spacing of the cell where the actual on-demand SSB is transmitted is SCS#1, if a specific time is set to X slots based on the subcarrier spacing of the cell where the on-demand SSB transmission instruction is transmitted, the cell where the actual on-demand SSB is transmitted can be set as in the following mathematical expression 2.

[0273]

[0274]

[0275]

[0276] Alternatively, the specific time may be preset based on the subcarrier spacing of the cell in which the on-demand SSB transmission instruction is transmitted or the subcarrier spacing of the cell in which the actual on-demand SSB is transmitted.

[0277] The above embodiment assumes a case where the numerology of a cell in which an on-demand SSB transmission instruction is transmitted is different from the numerology of a cell in which an actual on-demand SSB is transmitted. However, the same can be applied to a case where the numerology of a BWP in which an on-demand SSB transmission instruction is transmitted is different from the numerology of a BWP in which an actual on-demand SSB is transmitted in the same cell.

[0278] FIGS. 19A and 19B are timing diagrams for explaining a case in which it is determined that on-demand SSB transmission begins after a specific time according to embodiments of the present invention.

[0279] FIG. 19a corresponds to a case where the specific time T indicates a slot boundary at which on-demand SSB transmission begins, and FIG. 19b corresponds to a case where the specific time T indicates a symbol boundary at which on-demand SSB transmission begins.

[0280] In this embodiment, the point in time at which on-demand SSB transmission begins is set based on the SSB candidate position, regardless of whether the SSB is actually transmitted. However, the reference may be the actual SSB transmission position, rather than the SSB candidate position.

[0281] Additionally, even if it is determined that on-demand SSB transmission is initiated at the earliest SSB transmission occasion after a specific time has elapsed since the receipt of an on-demand SSB transmission instruction, a distinction can be made depending on whether the reference is an SSB candidate position or an SSB position actually transmitted.

[0282] When determining based on the actual transmitted SSB position, a method may be applied in which the on-demand SSB transmission is determined to start based on the first SSB position actually transmitted, or a method may be applied in which the on-demand SSB transmission is determined to start based on the SSB position where actual transmission is possible after a specific period of time has elapsed since the indicator was received.

[0283] At this time, there may be various cases depending on whether the time instance (time instance A) at which the terminal determines that an on-demand SSB will be transmitted is set to the slot boundary of the SSB actually transmitted or to the symbol boundary of the SSB actually transmitted.

[0284] FIGS. 20A to 20D are timing diagrams for explaining a case in which it is determined that on-demand SSB transmission starts from the earliest SSB transmission occasion after a specific time according to embodiments of the present invention.

[0285] Figure 20a may correspond to the case where time instance A is set to the slot boundary of the first SSB actually transmitted. In this case, since time instance A exists after a certain time (T) after receiving the on-demand SSB transmission instruction, it can be determined that the on-demand SSB transmission starts from the earliest SSB transmission occasion (SSB burst set #1 in Figure 20a).

[0286] Fig. 20b may correspond to a case where time instance A is set to the slot boundary of the first SSB actually transmitted. Since the SSB transmission occasion (SSB burst set #1 in Fig. 20b) starts before a specific time (T) after receiving the on-demand SSB transmission instruction, the terminal may determine the SSB transmission occasion as an invalid SSB burst set. Accordingly, the terminal may determine that the on-demand SSB transmission starts from the next SSB transmission occasion (SSB burst set #2 in Fig. 20b). Although the terminal may determine that the on-demand SSB is transmitted from SSB burst set #2, the on-demand SSB transmission may actually be performed from SSB burst set #1. Therefore, in this case, whether the terminal performs the synchronization and measurement procedure utilizing the on-demand SSB in SSB burst set #1 may be determined by the terminal implementation. In addition, the base station may recognize that the terminal determines SSB burst set #1 as an invalid SSB burst set and may not perform on-demand SSB transmission in the corresponding SSB burst set #1. In this case, it may be desirable for the terminal to determine that on-demand SSB is not transmitted in SSB burst set #1 and not perform synchronization and measurement procedures in the corresponding occasion. Even in this case, if the pattern of SSBs actually transmitted within the SSB burst set is '0011' and SSBs are actually transmitted only in the second slot, the terminal may determine SSB burst set #1 as a valid SSB burst set and perform SSB reception operation because the slot boundary of the actually transmitted SSB exists after time instance A.

[0287] Figure 20c can correspond to the case where time instance A is set to the symbol boundary of the first SSB actually transmitted. In this case, the slot boundary of the SSB transmission order starts before a specific time (T) after receiving the on-demand SSB transmission instruction. However, since time instance A is set based on the symbol boundary of the SSB position actually transmitted, the position exists after the specific time (T). Therefore, the SSB transmission order can be determined to be a valid SSB burst set, and it can be determined that on-demand SSB is transmitted starting from the SSB transmission order.

[0288] FIG. 20d can correspond to a case where an SSB transmission order starts before a specific time (T) after receiving an on-demand SSB transmission instruction, and the first SSB position actually transmitted also exists before the specific time (T). Since some SSBs are actually transmitted even after the specific time (T), the terminal can determine that the SSB transmission order is a partially valid SSB burst set. Accordingly, the terminal can determine that the on-demand SSB is transmitted from the SSB position actually transmitted that exists after the specific time (T). This method can be applied even when the time instance A is set to a slot boundary, and can be equally applied when the time instance A is set to a symbol boundary. In addition, in the case of FIG. 20d, if the determination is made based on the first SSB position actually transmitted, the SSB burst set #1 can be determined to be an invalid SSB burst set.

[0289] If it is determined that on-demand SSB transmission will start at the earliest SSB transmission order after a specific time has elapsed since the receipt of the on-demand SSB transmission instruction, the specific time may be set based on a slot boundary or symbol boundary. Additionally, the specific time may be predefined on a slot-by-slot or symbol-by-symbol basis.

[0290] Additionally, as previously explained, a specific time can be set in the same manner even if the numerology of the cell in which the on-demand SSB transmission instruction is transmitted and the numerology of the cell in which the actual on-demand SSB is transmitted are different.

[0291]

[0292] [Change on-demand SSB transmission cycle / Stop / resume on-demand SSB transmission]

[0293] In phase 3 of FIG. 16 described above, after SCell is activated, the terminal can measure CSI (channel state information) based on on-demand SSB and report it to the base station.

[0294] After SCell is activated, the UE can measure and report CSI (e.g., beam information and channel status information) to the base station based on on-demand SSB. However, SSB transmission may continue to be required for ongoing beam management and channel status monitoring. After SCell is activated (or after the UE reports CSI information to the base station based on on-demand SSB transmission), the on-demand SSB transmission cycle may differ from the on-demand SSB transmission cycle at the time when on-demand SSB transmission was first initiated.

[0295] This period can be the default SSB transmission period of 20 ms upon initial connection. If periodic SSB transmission was already occurring in the cell before on-demand SSB transmission was initiated, the previously used SSB transmission period can be maintained. Alternatively, this period can be a separately configured value, and it is generally desirable to set it to a value greater than the previous period.

[0296] The SSB transmission period value may be included in the on-demand SSB transmission-related information, in which case two transmission period values ​​may be included and transmitted in the on-demand SSB transmission-related information. When the on-demand SSB configuration information includes two transmission period values, the first transmission period value may be the value applied when the on-demand SSB transmission is first started. The second transmission period value may be applied after the UE reports CSI information to the base station based on the on-demand SSB transmission, or after the base station transmits a completion message to the UE after the SCell activation (or SCell synchronization) is completed based on the on-demand SSB transmission.

[0297] At this time, if the second transmission period value is not set, the second transmission period value may be set to 20ms, which is the default SSB transmission period at the time of initial connection, or, if periodic SSB was already being transmitted in the cell before the on-demand SSB transmission was performed, it may be maintained at the existing SSB transmission period value. Alternatively, the on-demand SSB transmission period may be changed via MAC CE.

[0298] For example, if the on-demand SSB transmission-related information includes two transmission cycle values, signaling can be performed via MAC CE as to which transmission cycle value to use. In this case, the signaling can be performed by indicating the index of one of the multiple transmission cycle values ​​set in advance, or by directly setting a specific transmission cycle value to be changed among the multiple transmission cycle values.

[0299] Meanwhile, while the above embodiments describe a case where two SSB transmission cycle values ​​are set, the same method can also be applied to cases where two or more SSB transmission cycle values ​​are set. Additionally, on-demand SSB transmission cycle changes can be performed not only via MAC CE but also via DCI or RRC signaling.

[0300] When changing the on-demand SSB transmission period via DCI, the on-demand SSB transmission period can be changed by signaling the corresponding period value or the index of the corresponding period via DCI. In this case, the DCI can be signaled to multiple UEs via a common PDCCH, or only to a specific UE via a UE-specific PDCCH. When signaled via the common PDCCH, the CRC of the corresponding PDCCH can be transmitted scrambled with a specific RNTI. Alternatively, the CRC of the corresponding PDCCH can be scrambled by reusing one of the existing RNTIs. When reusing one of the existing RNTIs, some of the bit fields that are not in use in the DCI using the corresponding RNTI can be used to indicate a change in the on-demand SSB transmission period, or some of the bit fields that were previously in use can be reinterpreted.

[0301]

[0302] If SSB is continuously transmitted at a specific cycle value after on-demand SSB transmission has been instructed, the base station may need to instruct to stop the SSB transmission. For example, if there are no more terminals that need SSB reception in the corresponding SCell or SSB transmission is not needed for other reasons, the base station may transmit an indicator instructing to stop on-demand SSB transmission in the corresponding SCell. In this case, the indicator for stopping on-demand SSB transmission may be transmitted by setting the corresponding information to '0' in the indicator indicating whether or not on-demand SSB transmission is transmitted through the above-described PDCCH, MAC CE, or RRC signaling (if on-demand SSB transmission is instructed, the corresponding information is set to '1'), and the terminal receiving this may understand the information as an instruction to stop on-demand SSB transmission.

[0303] After on-demand SSB transmission is instructed, if SSB is continuously transmitted at a specific period value, the base station may instruct to stop the SSB transmission as needed.

[0304] For example, if there are no longer any terminals requiring SSB reception on a particular SCell, or if SSB transmission becomes unnecessary for any other reason, the base station may instruct the SCell to stop on-demand SSB transmission.

[0305] At this time, the on-demand SSB transmission stop instruction can be transmitted by setting the value of the on-demand SSB transmission indicator transmitted via PDCCH, MAC CE, or RRC signaling to '0' (if on-demand SSB transmission is required, the value is set to '1' and transmitted). Upon receiving the indicator, the terminal can recognize that on-demand SSB transmission has been stopped.

[0306] To maximize network energy savings, it may be desirable to stop on-demand SSB transmissions once the base station determines that SCell activation (or SCell synchronization) is complete after the on-demand SSB transmissions have been transmitted according to the configured transmission interval (e.g., the configured number of SSB transmissions, the start and end times of SSB transmissions, etc.). At this time, reporting and confirmation procedures from the terminal may be required for the base station to determine whether SCell activation is complete.

[0307] If the terminal reports CSI information measured based on the transmitted SSB to the base station, the base station can determine that SCell activation is complete and subsequently discontinue on-demand SSB transmission. Alternatively, if the terminal transmits an SCell activation (or SCell synchronization) completion message to the base station based on the transmitted SSB, the base station can discontinue on-demand SSB transmission after receiving the message.

[0308] At this time, the SCell activation completion message can be reported using UCI (Uplink Control Information) through PUCCH, MAC CE through PUSCH, or RRC signaling.

[0309] Even after on-demand SSB transmission is suspended, CSI-RS can be configured and transmitted for each terminal for continued beam management and channel status measurement. CSI-RS configuration information can be transmitted via terminal-specific RRC signaling. This configuration information can be transmitted to the terminal after on-demand SSB transmission is suspended. Alternatively, this configuration information can be transmitted together with on-demand SSB transmission-related configuration information in advance or separately.

[0310] If the base station does not receive a CSI measurement report or SCell activation (or SCell synchronization) completion message from the terminal for a predefined or set period of time after transmitting an on-demand SSB according to the set information, the base station may determine that the terminal has not completed SCell activation or synchronization.

[0311] In this case, the base station can perform retransmission of on-demand SSB, and the retransmission of on-demand SSB can be performed in the same manner according to existing configuration information, or can be performed based on new configuration information.

[0312] New configuration information may be adjusted compared to existing configuration information. For example, the new configuration information may set a higher number of SSB burst sets to be transmitted, a longer SSB transmission interval, a shorter SSB transmission period, or a shorter SSB transmission interval along with a higher number of SSB burst sets to be transmitted or a longer SSB transmission interval.

[0313] The new SSB configuration information may be transmitted to the UE via DCI, MAC CE, or RRC signaling, or may be transmitted together with the configuration information for the initial on-demand SSB transmission. Alternatively, the new configuration information may be transmitted additionally after the initial on-demand SSB transmission if a CSI measurement report or SCell activation completion message is not received.

[0314] Additionally, similar to the on-demand SSB cycle setting, the configuration information for the initial on-demand SSB transmission may include information on the number of on-demand SSB burst sets to be transmitted and / or on-demand SSB transmission intervals. In this case, a new number of transmissions or transmission intervals may be set via DCI, MAC CE, or RRC signaling as needed. Alternatively, the overall on-demand SSB configuration information may be set multiple times in advance, and an index indicating specific configuration information may be indicated via DCI, MAC CE, or RRC signaling.

[0315]

[0316] On-demand SSB transmission of an SCell can be triggered through backhaul signaling (e.g., X2 interface) between the PCell and the SCell. If on-demand SSB transmission of an SCell is determined to be necessary based on a request from a UE or a judgment of the PCell, the PCell can trigger on-demand SSB transmission to the SCell through the X2 interface. The SCell can perform on-demand SSB transmission according to the configured on-demand SSB information. At this time, it may be necessary to notify the UE of whether or not on-demand SSB transmission has begun. To this end, whether or not on-demand SSB transmission has begun can be indicated explicitly to the UE by separate indication information or implicitly by transmitting on-demand SSB configuration information.

[0317]

[0318] When on-demand SSB is transmitted, the terminal can perform measurements based on the on-demand SSB and then perform CSI reporting. If periodic SSB is already being transmitted in the cell in addition to on-demand SSB, a CSI reporting method that takes this into account may be required.

[0319] A terminal can receive both on-demand SSB and periodic (always-on) SSB. Therefore, measurement reports for both types of SSBs (on-demand SSB and periodic SSB) can be configured in a single CSI reporting configuration. In this case, the terminal can perform CSI reporting in the following manner. For example, a CSI report can be generated by reflecting the measurement results from both on-demand SSB #1 and the existing periodic SSB #1. It may be desirable for the SSBs actually transmitted in an on-demand SSB burst to match those actually transmitted in a periodic SSB burst.

[0320] Additionally, it may be desirable to integrate on-demand and periodic SSB measurement results in a single CSI report only when the frequency locations where on-demand and periodic SSBs are transmitted coincide, or when the frequency locations of the two SSBs differ within a specific range. The specific range may be set in advance through system information or defined by the standard.

[0321]

[0322] In situations where on-demand and periodic SSB overlap, network configurations may result in one SSB being dropped and the other being transmitted alone. In this case, since the terminal will always receive only one SSB, it may be desirable to report only through a single CSI reporting configuration, rather than separately considering on-demand and periodic SSB for CSI reporting.

[0323]

[0324] Alternatively, separate CSI reporting settings can be configured for on-demand SSB and periodic SSB, and CSI reporting can be performed separately. In this case, CSI reporting settings for measurement results using on-demand SSB and CSI reporting settings for measurement results using periodic SSB can be configured separately.

[0325] In this case, the SSBs actually transmitted in the on-demand SSB burst and the SSBs actually transmitted in the periodic SSB burst can be set individually or in a way that the two pieces of information are set to match each other.

[0326]

[0327] The operations of the method according to an embodiment of the present invention can be implemented as a computer-readable program or code on a computer-readable recording medium. A computer-readable recording medium includes any type of recording device that stores information readable by a computer system. Furthermore, a computer-readable recording medium can be distributed across network-connected computer systems, allowing the computer-readable program or code to be stored and executed in a distributed manner.

[0328] Additionally, the computer-readable recording medium may include hardware devices specifically configured to store and execute program instructions, such as ROM, RAM, flash memory, etc. The program instructions may include not only machine language codes produced by a compiler, but also high-level language codes that can be executed by a computer using an interpreter, etc.

[0329] While some aspects of the present invention have been described in the context of a device, they may also represent a description of a corresponding method, wherein a block or device corresponds to a method step or a feature of a method step. Similarly, aspects described in the context of a method may also be described as a corresponding block or item or a feature of a corresponding device. Some or all of the method steps may be performed by (or using) a hardware device, such as, for example, a microprocessor, a programmable computer, or an electronic circuit. In some embodiments, at least one or more of the most important method steps may be performed by such a device.

[0330] In embodiments, a programmable logic device (e.g., a field-programmable gate array) may be used to perform some or all of the functions of the methods described herein. In embodiments, the field-programmable gate array may operate in conjunction with a microprocessor to perform one of the methods described herein. In general, the methods are preferably performed by some hardware device.

[0331] Although the present invention has been described above with reference to preferred embodiments thereof, it will be understood by those skilled in the art that various modifications and changes may be made to the present invention without departing from the spirit and scope of the present invention as set forth in the claims below.

Claims

1. By terminal method, A step of receiving at least one on-demand synchronization signal block (SSB) setting from a base station via a first signaling; A step of receiving an activation or deactivation instruction for one or more first secondary cells (SCells) from the base station through second signaling; A step of receiving an activation or deactivation instruction of on-demand SSB transmission for the one or more first SCell(s) from the base station through a third signaling; and A step of performing SSB reception on one or more of the second SCell(s) when an activation instruction for on-demand SSB transmission for one or more of the first SCell(s) is received through the third signaling, method.

2. In claim 1, The above first signaling uses an RRC (radio resource control) message. method.

3. In claim 1, Further comprising a step of receiving configuration information for an existing SSB from the base station, method.

4. In claim 3, If the first part to be included in the at least one on-demand SSB setting is identical to the second part of the setting information for the existing SSB, the first part is omitted from the at least one on-demand SSB setting. method.

5. In claim 3, When an instruction is received to ignore the configuration information for the above existing SSB, the terminal does not perform SSB reception based on the configuration information for the always transmitted SSB. method.

6. In claim 1, If the at least one on-demand SSB configuration is a plurality of on-demand SSB configurations, each of the plurality of on-demand SSB configurations includes at least one of a frequency at which on-demand SSBs are transmitted, a bitmap indicating the position(s) of SSB(s) actually transmitted within an on-demand SSB burst, a transmission period for on-demand SSBs, a subcarrier spacing for on-demand SSBs, a physical cell identifier (PCI) for on-demand SSBs, a time position for on-demand SSBs, a transmission power for on-demand SSBs, or a number of on-demand SSB bursts to be transmitted. method.

7. In claim 1, If the at least one on-demand SSB configuration is one on-demand SSB configuration, the one on-demand SSB configuration includes at least one of one or more frequencies at which on-demand SSBs are transmitted, one or more bitmaps indicating the position(s) of SSB(s) actually transmitted within an on-demand SSB burst, one or more transmission periods for the on-demand SSBs, one or more subcarrier intervals for the on-demand SSBs, one or more PCIs for the on-demand SSBs, a plurality of time positions for the on-demand SSBs, a plurality of transmit powers for the on-demand SSBs, or a number of on-demand SSB bursts to be transmitted. method.

8. In claim 1, The second signaling and the third signaling utilize at least one medium access control (MAC) control element (CE), wherein the at least one MAC CE includes a first bitmap for an activation indication or a deactivation indication for the one or more first SCell(s) and a second bitmap(s) for an activation indication or a deactivation indication of on-demand SSB transmission for the one or more first SCell(s). method.

9. In claim 8, If the at least one on-demand SSB setting is a plurality of on-demand SSB settings, the second bitmap(s) are a plurality of bitmaps, and if the at least one on-demand SSB setting is one on-demand SSB setting, the second bitmap(s) is one bitmap. method.

10. In claim 8, The bits of the first bitmap and the bits of each of the second bitmap(s) correspond one-to-one, method.

11. In claim 1, The second signaling uses a first MAC CE and the third signaling uses a second MAC CE, wherein the first MAC CE includes a bitmap for an activation indication or a deactivation indication for the one or more first SCell(s), and the second MAC CE includes at least one of information indicating SCell(s) on which on-demand SSBs are to be transmitted, information indicating one of the at least one on-demand SSB configuration, information indicating a transmission period of on-demand SSBs, or information indicating the number of on-demand SSB bursts to be transmitted. method.

12. In claim 1, The terminal assumes that the on-demand SSB is transmitted starting from the first slot that includes the SSB actually transmitted within the first SSB burst among the slots after the second time point when the first time point related to the third signaling has elapsed, and performs the SSB reception. method.

13. In claim 12, When the third signaling uses MAC CE, the first point in time corresponds to slot m in which HARQ (hybrid automatic repeat request)-ACK (acknowledgement) information for the MAC CE is transmitted, the first time is a time corresponding to (the number of slots corresponding to 3 ms + X slots (where X is a natural number greater than or equal to 1)), and the number of slots corresponding to 3 ms is determined based on the subcarrier spacing of the activated uplink bandwidth part (BWP) or the activated downlink BWP, and the second time corresponds to a slot after the first time has elapsed from the slot m. method.

14. By the method of the base station, A step of transmitting at least one on-demand synchronization signal block (SSB) configuration to a terminal via first signaling; A step of transmitting an activation or deactivation instruction for one or more first secondary cells (SCells) to the terminal through second signaling; A step of transmitting an activation or deactivation instruction of on-demand SSB transmission for one or more of the first SCell(s) to the terminal through third signaling; and A step of performing SSB transmission on one or more of the second SCell(s) when an activation instruction for on-demand SSB transmission for one or more of the first SCell(s) is transmitted through the third signaling, method.

15. In claim 14, The second signaling and the third signaling utilize at least one medium access control (MAC) control element (CE), wherein the at least one MAC CE includes a first bitmap for an activation indication or a deactivation indication for the one or more first SCell(s) and a second bitmap(s) for an activation indication or a deactivation indication of on-demand SSB transmission for the one or more first SCell(s). method.

16. In claim 15, If the at least one on-demand SSB setting is a plurality of on-demand SSB settings, the second bitmap(s) are a plurality of bitmaps, and if the at least one on-demand SSB setting is one on-demand SSB setting, the second bitmap(s) is one bitmap. method.

17. In claim 15, The bits of the first bitmap and the bits of each of the second bitmap(s) correspond one-to-one, method.

18. In claim 14, The second signaling uses a first MAC CE and the third signaling uses a second MAC CE, wherein the first MAC CE includes a bitmap for an activation indication or a deactivation indication for the one or more first SCell(s), and the second MAC CE includes at least one of information indicating SCell(s) on which on-demand SSBs are to be transmitted, information indicating one of the at least one on-demand SSB configuration, information indicating a transmission period of on-demand SSBs, or information indicating the number of on-demand SSB bursts to be transmitted. method.

19. A terminal comprising at least one processor, wherein the at least one processor: A step of receiving at least one on-demand synchronization signal block (SSB) setting from a base station via a first signaling; A step of receiving an activation or deactivation instruction for one or more first secondary cells (SCells) from the base station through second signaling; A step of receiving an activation or deactivation instruction of on-demand SSB transmission for the one or more first SCell(s) from the base station through a third signaling; and When an activation instruction for on-demand SSB transmission for one or more second SCell(s) among the one or more first SCell(s) is received through the third signaling, a step of performing SSB reception on the one or more second SCell(s) is performed. Terminal.

20. In claim 19, The second signaling and the third signaling utilize at least one medium access control (MAC) control element (CE), wherein the at least one MAC CE includes a first bitmap for an activation or deactivation indication for the one or more first SCell(s) and a second bitmap(s) for an activation or deactivation indication of on-demand SSB transmission for the one or more first SCell(s). Terminal.

Images