WO2025116642A1 - Method and device for transmitting and receiving synchronization signal in wireless communication system - Google Patents

Abstract

Disclosed are a method and device for performing communication in a wireless communication system. The method performed by a terminal according to an embodiment of the present disclosure may comprise the steps of: receiving, from a base station, first configuration information related to an on-demand synchronization signal for a first cell; and, on the basis of receiving the on-demand synchronization signal from the base station within a specific unit time, transmitting first information related to a first beam failure to the base station on the basis of the on-demand synchronization signal, wherein, on the basis of not receiving the on-demand synchronization signal from the base station, second information related to a second beam failure is transmitted to the base station by the terminal on the basis of a reference signal, and the specific unit time may be based on the first configuration information.

Description

Method and device for transmitting and receiving synchronous signals in a wireless communication system

The present disclosure relates to a wireless communication system, and more specifically, to a method and device for transmitting and receiving a synchronous signal in a wireless communication system.

Mobile communication systems were developed to provide voice services while ensuring user activity. However, mobile communication systems have expanded their scope to include data services as well as voice, and currently, due to the explosive increase in traffic, resource shortages are occurring and users are demanding higher-speed services, so more advanced mobile communication systems are required.

The requirements for the next generation mobile communication system are that it should be able to accommodate explosive data traffic, dramatically increase the data rate per user, accommodate a greatly increased number of connected devices, support very low end-to-end latency, and support high energy efficiency. To this end, various technologies are being studied, including dual connectivity, massive multiple input multiple output (MIMO), in-band full duplex, non-orthogonal multiple access (NOMA), super wideband support, and device networking.

The technical problem of the present disclosure is to provide a method and device for transmitting and receiving a synchronous signal in a wireless communication system.

The technical problem of the present disclosure is to provide a method and device for transmitting and receiving an on-demand synchronization signal block (SSB) in a wireless communication system to which network energy saving (NES) is applied.

The technical problems to be achieved in the present disclosure are not limited to the technical problems mentioned above, and other technical problems not mentioned will be clearly understood by a person having ordinary skill in the technical field to which the present disclosure belongs from the description below.

A method according to one embodiment of the present disclosure comprises the steps of: receiving, by a terminal, from a base station, first configuration information related to an on-demand synchronization signal for a first cell; and transmitting, by the terminal to the base station, first information related to a first beam failure based on the on-demand synchronization signal based on reception of the on-demand synchronization signal from the base station within a specific unit of time; and transmitting, by the terminal to the base station, second information related to a second beam failure based on a reference signal based on not receiving the on-demand synchronization signal from the base station, wherein the specific unit of time can be based on the first configuration information.

According to another embodiment of the present disclosure, a method comprises the steps of: transmitting, by a base station, first configuration information related to an on-demand synchronization signal for a first cell to a terminal; and, based on receiving the on-demand synchronization signal from the base station within a specific unit of time, receiving, by the base station, from the terminal, first information related to a first beam failure based on the on-demand synchronization signal, and, based on not receiving the on-demand synchronization signal from the base station, second information related to a second beam failure based on a reference signal is received by the base station from the terminal, wherein the specific unit of time can be based on the first configuration information.

According to various embodiments of the present disclosure, a method and device for transmitting and receiving a synchronous signal in a wireless communication system can be provided.

According to various embodiments of the present disclosure, a method and device for transmitting and receiving on-demand SSB in a wireless communication system to which network energy saving is applied are provided.

According to various embodiments of the present disclosure, energy consumption of terminals/base stations due to on-demand SSB transmission and reception can be reduced by controlling cell states based on on-demand SSB measurement results.

The effects obtainable from the present disclosure are not limited to the effects mentioned above, and other effects not mentioned will be clearly understood by a person having ordinary skill in the art to which the present disclosure belongs from the description below.

The accompanying drawings, which are incorporated in and are incorporated in and are intended to aid in understanding the present disclosure, provide embodiments of the present disclosure and together with the detailed description, describe the technical features of the present disclosure.

Figure 1 illustrates the structure of a wireless communication system to which the present disclosure can be applied.

FIG. 2 illustrates a frame structure in a wireless communication system to which the present disclosure can be applied.

FIG. 3 illustrates a resource grid in a wireless communication system to which the present disclosure can be applied.

FIG. 4 illustrates a physical resource block in a wireless communication system to which the present disclosure can be applied.

FIG. 5 illustrates a slot structure in a wireless communication system to which the present disclosure can be applied.

FIG. 6 illustrates physical channels used in a wireless communication system to which the present disclosure can be applied and a general signal transmission and reception method using the same.

Figure 7 is a diagram for explaining the operation of transmission and reception of on-demand SSB.

FIG. 8 is a flowchart for explaining the operation of a terminal in a wireless communication system according to one embodiment of the present disclosure.

FIG. 9 is a flowchart for explaining the operation of a base station in a wireless communication system according to one embodiment of the present disclosure.

FIG. 10 illustrates a block diagram of a wireless communication device according to one embodiment of the present disclosure.

Hereinafter, preferred embodiments according to the present disclosure will be described in detail with reference to the accompanying drawings. The detailed description set forth below together with the accompanying drawings is intended to explain exemplary embodiments of the present disclosure and is not intended to represent the only embodiments in which the present disclosure may be practiced. The following detailed description includes specific details in order to provide a thorough understanding of the present disclosure. However, one of ordinary skill in the art will appreciate that the present disclosure may be practiced without these specific details.

In some cases, to avoid obscuring the concepts of the present disclosure, well-known structures and devices may be omitted or illustrated in block diagram format focusing on the core functions of each structure and device.

In the present disclosure, when a component is said to be "connected", "coupled" or "connected" to another component, this may include not only a direct connection relationship, but also an indirect connection relationship in which another component exists between them. Also, the terms "comprises" or "has" in the present disclosure specify the presence of the mentioned features, steps, operations, elements and/or components, but do not exclude the presence or addition of one or more other features, steps, operations, elements, components and/or groups thereof.

In this disclosure, the terms “first,” “second,” etc. are used only to distinguish one component from other components and are not used to limit the components, and do not limit the order or importance among the components unless specifically stated otherwise. Accordingly, within the scope of this disclosure, a first component in one embodiment may be referred to as a second component in another embodiment, and similarly, a second component in one embodiment may be referred to as a first component in another embodiment.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of the claims. As used in the description of the embodiments and the appended claims, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly dictates otherwise. The term "and/or" as used herein may refer to one of the associated enumerated items or is meant to refer to and encompass any and all possible combinations of two or more of them. Furthermore, the word "/" used between words in this disclosure has the same meaning as "and/or" unless otherwise stated.

The present disclosure describes a wireless communication network or a wireless communication system, and an operation performed in a wireless communication network may be performed in a process of controlling the network and transmitting or receiving a signal from a device (e.g., a base station) that manages the wireless communication network, or in a process of transmitting or receiving a signal with or between terminals connected to the wireless network.

In the present disclosure, transmitting or receiving a channel means transmitting or receiving information or a signal through the channel. For example, transmitting a control channel means transmitting control information or a signal through the control channel. Similarly, transmitting a data channel means transmitting data information or a signal through the data channel.

Hereinafter, downlink (DL) means communication from a base station to a terminal, and uplink (UL) means communication from a terminal to a base station. In the downlink, a transmitter may be part of a base station, and a receiver may be part of a terminal. In the uplink, a transmitter may be part of a terminal, and a receiver may be part of a base station. The base station may be expressed as a first communication device, and the terminal may be expressed as a second communication device. A base station (BS) may be replaced by terms such as a fixed station, a Node B, an evolved-NodeB (eNB), a Next Generation NodeB (gNB), a base transceiver system (BTS), an Access Point (AP), a network (5G network), an Artificial Intelligence (AI) system/module, a road side unit (RSU), a robot, a drone (UAV: Unmanned Aerial Vehicle), an Augmented Reality (AR) device, and a Virtual Reality (VR) device. In addition, the terminal may be fixed or mobile, and may be replaced with terms such as UE (User Equipment), MS (Mobile Station), UT (user terminal), MSS (Mobile Subscriber Station), SS (Subscriber Station), AMS (Advanced Mobile Station), WT (Wireless terminal), MTC (Machine-Type Communication) device, M2M (Machine-to-Machine) device, D2D (Device-to-Device) device, vehicle, RSU (road side unit), robot, AI (Artificial Intelligence) module, UAV (Unmanned Aerial Vehicle), AR (Augmented Reality) device, and VR (Virtual Reality) device.

The technology below can be used in various wireless access systems, such as CDMA, FDMA, TDMA, OFDMA, and SC-FDMA. CDMA can be implemented with wireless technologies such as UTRA (Universal Terrestrial Radio Access) or CDMA2000. TDMA can be implemented with wireless technologies such as GSM (Global System for Mobile communications)/GPRS (General Packet Radio Service)/EDGE (Enhanced Data Rates for GSM Evolution). OFDMA can be implemented with wireless technologies such as IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802-20, E-UTRA (Evolved UTRA). UTRA is a part of UMTS (Universal Mobile Telecommunications System). 3GPP(3rd Generation Partnership Project) LTE(Long Term Evolution) is a part of E-UMTS(Evolved UMTS) that uses E-UTRA, and LTE-A(Advanced)/LTE-A pro is an evolved version of 3GPP LTE. 3GPP NR(New Radio or New Radio Access Technology) is an evolved version of 3GPP LTE/LTE-A/LTE-A pro.

For the sake of clarity, the description is based on a 3GPP communication system (e.g., LTE-A, NR), but the technical idea of the present disclosure is not limited thereto. LTE refers to technology after 3GPP TS (Technical Specification) 36.xxx Release 8. Specifically, LTE technology after 3GPP TS 36.xxx Release 10 is referred to as LTE-A, and LTE technology after 3GPP TS 36.xxx Release 13 is referred to as LTE-A pro. 3GPP NR refers to technology after TS 38.xxx Release 15. LTE/NR may be referred to as a 3GPP system. “xxx” refers to a standard document detail number. LTE/NR may be collectively referred to as a 3GPP system. With respect to background technologies, terms, abbreviations, etc. used in the description of the present disclosure, reference may be made to matters described in standard documents published prior to the present disclosure. For example, reference may be made to the following documents:

For 3GPP LTE, see TS 36.211 (Physical channels and modulation), TS 36.212 (Multiplexing and channel coding), TS 36.213 (Physical layer procedures), TS 36.300 (General description) and TS 36.331 (Radio resource control).

For 3GPP NR, see TS 38.211 (Physical channels and modulation), TS 38.212 (Multiplexing and channel coding), TS 38.213 (Physical layer procedures for control), TS 38.214 (Physical layer procedures for data), TS 38.300 (Overall description of NR and New Generation-Radio Access Network (NG-RAN)), and TS 38.331 (Radio Resource Control Protocol Specification).

The abbreviations of terms that may be used in this disclosure are defined as follows.

- BM: beam management

- CQI: channel quality indicator

- CRI: Channel state information - reference signal resource indicator

- CSI: channel state information

- CSI-IM: Channel state information - interference measurement

- CSI-RS: Channel state information - reference signal

- DMRS: Demodulation reference signal

- FDM: Frequency division multiplexing

- FFT: fast Fourier transform

- IFDMA: interleaved frequency division multiple access

- IFFT: inverse fast Fourier transform

- L1-RSRP: Layer 1 reference signal received power

- L1-RSRQ: Layer 1 reference signal received quality

- MAC: Medium Access Control

- NZP: non-zero power

- OFDM: Orthogonal frequency division multiplexing

- PDCCH: physical downlink control channel

- PDSCH: physical downlink shared channel

- PMI: precoding matrix indicator

- RE: resource element

- RI: Rank indicator

- RRC: radio resource control

- RSSI: received signal strength indicator

- Rx: Reception

- QCL: quasi co-location

- SINR: signal to interference and noise ratio

- SSB (or SS/PBCH block): Synchronization signal block (including primary synchronization signal (PSS), secondary synchronization signal (SSS), and physical broadcast channel (PBCH))

- TDM: time division multiplexing

- TRP: transmission and reception point

- TRS: Tracking reference signal

- Tx: transmission

- UE: user equipment

- ZP: zero power

System General

As more and more communication devices require greater communication capacity, there is a growing need for improved mobile broadband communication over existing radio access technology (RAT). In addition, massive MTC (machine type communications), which connects a large number of devices and objects to provide various services anytime and anywhere, is also one of the major issues to be considered in next-generation communications. In addition, a communication system design that considers services/terminals that are sensitive to reliability and latency is being discussed. The introduction of next-generation RATs that consider enhanced mobile broadband communication (eMBB), massive MTC (MMTC), ultra-reliable and low latency communication (URLLC), etc. is being discussed, and in this disclosure, the technology is referred to as NR for convenience. NR is an expression indicating an example of 5G RAT.

The new RAT system including NR uses OFDM transmission scheme or similar transmission scheme. The new RAT system may follow OFDM parameters different from those of LTE. Or, the new RAT system may follow the existing LTE/LTE-A numerology but support a larger system bandwidth (e.g., 100MHz). Or, a single cell may support multiple numerologies. That is, terminals operating with different numerologies may coexist in a single cell.

A numerology corresponds to one subcarrier spacing in the frequency domain. Different numerologies can be defined by scaling the reference subcarrier spacing by an integer N.

Figure 1 illustrates the structure of a wireless communication system to which the present disclosure can be applied.

Referring to Fig. 1, the NG-RAN consists of gNBs providing NG-RA (NG-Radio Access) user plane (i.e., new AS (access stratum) sublayer/PDCP (packet data convergence protocol)/RLC (radio link control)/MAC/PHY) and control plane (RRC) protocol termination for UE. The gNBs are interconnected via Xn interface. The gNBs are also connected to NGC (New Generation Core) via NG interface. More specifically, the gNBs are connected to AMF (Access and Mobility Management Function) via N2 interface and to UPF (User Plane Function) via N3 interface.

FIG. 2 illustrates a frame structure in a wireless communication system to which the present disclosure can be applied.

NR system can support multiple numerologies, where the numerology can be defined by subcarrier spacing and cyclic prefix (CP) overhead. Here, multiple subcarrier spacings can be derived by scaling the base (reference) subcarrier spacing by an integer N (or μ). Also, even if it is assumed that very low subcarrier spacing is not used at very high carrier frequencies, the numerology used can be selected independently of the frequency band. In addition, NR system can support various frame structures according to multiple numerologies.

Below, we examine OFDM numerologies and frame structures that can be considered in NR systems. A number of OFDM numerologies supported in NR systems can be defined as shown in Table 1 below.

μ Δf=2 ^μ ·15 [kHz] CP 0 15 Normal 1 30 common 2 60 General, Extended 3 120 common 4 240 common

NR supports multiple numerologies (or subcarrier spacing (SCS)) to support various 5G services. For example, when the SCS is 15 kHz, it supports a wide area in traditional cellular bands, when the SCS is 30 kHz/60 kHz, it supports dense-urban, lower latency, and wider carrier bandwidth, and when the SCS is 60 kHz or higher, it supports a bandwidth larger than 24.25 GHz to overcome phase noise. The NR frequency band is defined by two types of frequency ranges (FR1, FR2). FR1 and FR2 can be configured as shown in Table 2 below. In addition, FR2 can mean millimeter wave (mmW).

Frequency Range designation Corresponding frequency range Subcarrier Spacing FR1 410MHz - 7125MHz 15, 30, 60kHz FR2 24250MHz - 52600MHz 60, 120, 240kHz

With respect to the frame structure in an NR system, the sizes of various fields in the time domain are expressed in multiples of a time unit of T _c = 1/(Δf _max ·N _f ). Here, Δf _max = 480 · 10 ³ Hz and N _f = 4096. Downlink and uplink transmissions are organized into radio frames having a duration of T _f = 1/(Δf _max N _f /100) · T _c = 10 ms. Here, the radio frame consists of 10 subframes, each having a duration of T _sf = (Δf _max N _f /1000) · T _c = 1 ms. In this case, there can be one set of frames for uplink and one set of frames for downlink. In addition, transmission in uplink frame number i from a terminal must start before the start of the corresponding downlink frame at the terminal T _TA =(N _TA +N _TA,offset )T _c . For a subcarrier spacing configuration μ , slots are numbered in increasing order of n _s ^μ ∈{0,..., N _slot ^subframe,μ -1} within a subframe and in increasing order of n _s,f ^μ ∈{0,..., N _slot ^frame,μ -1} within a radio frame. A slot consists of consecutive OFDM symbols of N _symb ^slot , where N _symb ^slot is determined according to a CP. The start of slot n _s ^μ in a subframe is temporally aligned with the start of OFDM symbol n _s ^μ N _symb ^slot in the same subframe. Not all terminals can transmit and receive simultaneously, which means that not all OFDM symbols of a downlink slot or an uplink slot cannot be utilized. Table 3 shows the number of OFDM symbols per slot (N _symb ^slot ), the number of slots per radio frame (N _slot ^frame,μ ), and the number of slots per subframe (N _slot ^subframe,μ ) in the general CP, and Table 4 shows the number of OFDM symbols per slot, the number of slots per radio frame, and the number of slots per subframe in the extended CP.

μ N _symb ^slot N _slot ^frame,μ N _slot ^subframe,μ 0 14 10 1 1 14 20 2 2 14 40 4 3 14 80 8 4 14 160 16

μ N _symb ^slot N _slot ^frame,μ N _slot ^subframe,μ 2 12 40 4

FIG. 2 is an example when μ=2 (SCS is 60 kHz), and referring to Table 3, 1 subframe can include 4 slots. 1 subframe={1,2,4} slot illustrated in FIG. 2 is an example, and the number of slot(s) that can be included in 1 subframe is defined as in Table 3 or Table 4. In addition, a mini-slot can include 2, 4, or 7 symbols, or more or fewer symbols. With respect to physical resources in an NR system, an antenna port, a resource grid, a resource element, a resource block, a carrier part, etc. can be considered.

Hereinafter, the physical resources that can be considered in the NR system will be specifically examined. First, with respect to an antenna port, an antenna port is defined such that a channel through which a symbol on the antenna port is carried can be inferred from a channel through which another symbol on the same antenna port is carried. If a large-scale property of a channel through which a symbol on one antenna port is carried can be inferred from a channel through which a symbol on another antenna port is carried, the two antenna ports can be said to be in a QC/QCL (quasi co-located or quasi co-location) relationship. Here, the large-scale property includes one or more of delay spread, Doppler spread, frequency shift, average received power, and received timing.

FIG. 3 illustrates a resource grid in a wireless communication system to which the present disclosure can be applied. Referring to FIG. 3, it is exemplarily described that the resource grid is composed of N _RB ^μ N _sc ^RB subcarriers in the frequency domain and one subframe is composed of 14·2 ^μ OFDM symbols, but is not limited thereto. In an NR system, a transmitted signal is described by one or more resource grids composed of N _RB ^μ N _sc ^RB subcarriers and 2 ^μ N _symb ^(μ) OFDM symbols. Here, N _RB ^μ ≤ N _RB ^max,μ . The N _RB ^max,μ represents a maximum transmission bandwidth, which may vary between uplink and downlink as well as numerologies. In this case, one resource grid may be configured for each μ and each antenna port p. Each element of the resource grid for μ and antenna port p is referred to as a resource element and is uniquely identified by an index pair (k,l').

Here, k=0,...,N _RB ^μ N _sc ^RB -1 is an index on the frequency domain, and l'=0,...,2 ^μ N _symb ^(μ) -1 designates the position of a symbol within a subframe. When designating a resource element in a slot, an index pair (k,l) is used. Here, l=0,...,N _symb ^μ -1. The resource element (k,l') for μ and antenna port p corresponds to a complex value a _k,l' ^(p,μ) . If there is no risk of confusion or if a particular antenna port or numerology is not specified, the indices p and μ can be dropped, resulting in a complex value a _k,l' ^(p) or a _k,l' . Furthermore, a resource block (RB) is defined as N _sc ^RB =12 consecutive subcarriers on the frequency domain.

Point A serves as a common reference point of the resource block grid and is obtained as follows.

- offsetToPointA for Primary Cell (PCell) downlink represents the frequency offset between point A and the lowest subcarrier of the lowest resource block overlapping with the SS/PBCH block used by the UE for initial cell selection. It is expressed in resource block units assuming 15 kHz subcarrier spacing for FR1 and 60 kHz subcarrier spacing for FR2.

- absoluteFrequencyPointA represents the frequency-position of point A expressed as ARFCN (absolute radio-frequency channel number).

Common resource blocks are numbered from 0 upward in the frequency domain for the subcarrier spacing setting μ. The center of subcarrier 0 of common resource block 0 for the subcarrier spacing setting μ coincides with 'point A'. The relationship between common resource block number n _CRB ^μ in the frequency domain and resource elements (k, l) for the subcarrier spacing setting μ is given by the following mathematical expression 1.

In Equation 1, k is defined relative to point A such that k = 0 corresponds to the subcarrier centered at point A. The physical resource blocks are numbered from 0 to N _BWP,i ^size,μ -1 within a bandwidth part (BWP), where i is the number of the BWP. The relationship between a physical resource block n _PRB and a common resource block n _CRB in a BWP i is given by Equation 2 below.

N _BWP,i ^start,μ is the common resource block where the BWP starts relative to common resource block 0.

FIG. 4 illustrates a physical resource block in a wireless communication system to which the present disclosure can be applied. FIG. 5 illustrates a slot structure in a wireless communication system to which the present disclosure can be applied.

Referring to FIGS. 4 and 5, a slot includes multiple symbols in the time domain. For example, in the case of normal CP, one slot includes 7 symbols, but in the case of extended CP, one slot includes 6 symbols.

A carrier includes multiple subcarriers in the frequency domain. An RB (Resource Block) is defined as multiple (e.g., 12) consecutive subcarriers in the frequency domain. A BWP (Bandwidth Part) is defined as multiple consecutive (physical) resource blocks in the frequency domain, and can correspond to one numerology (e.g., SCS, CP length, etc.). A carrier can include up to N (e.g., 5) BWPs. Data communication is performed through activated BWPs, and only one BWP can be activated for one terminal. Each element in the resource grid is referred to as a Resource Element (RE), and one complex symbol can be mapped.

The NR system can support up to 400 MHz per component carrier (CC). If a terminal operating in such a wideband CC always operates with the radio frequency (RF) chip for the entire CC turned on, the terminal battery consumption may increase. Or, when considering multiple use cases (e.g., eMBB, URLLC, Mmtc, V2X, etc.) operating in a single wideband CC, different numerologies (e.g., subcarrier spacing, etc.) may be supported for each frequency band within the CC. Or, the capability for maximum bandwidth may be different for each terminal. Considering this, the base station may instruct the terminal to operate in only a part of the bandwidth, not the entire bandwidth of the wideband CC, and the part of the bandwidth is conveniently defined as the bandwidth part (BWP). A BWP can be composed of consecutive RBs on the frequency axis and can correspond to one numerology (e.g., subcarrier spacing, CP length, slot/mini-slot interval).

Meanwhile, the base station can set multiple BWPs even within one CC set for the terminal. For example, in the PDCCH monitoring slot, a BWP that occupies a relatively small frequency domain can be set, and the PDSCH indicated by the PDCCH can be scheduled on a larger BWP.

Alternatively, when UEs are concentrated in a specific BWP, some terminals can be set to a different BWP for load balancing. Alternatively, considering frequency domain inter-cell interference cancellation between neighboring cells, some spectrum in the middle of the entire bandwidth can be excluded and both BWPs can be set within the same slot. That is, the base station can set at least one DL/UL BWP for a terminal associated with a wideband CC.

The base station can activate (by L1 signaling or MAC CE (Control Element) or RRC signaling, etc.) at least one DL/UL BWP among the DL/UL BWP(s) configured at a specific point in time. In addition, the base station can instruct switching to another configured DL/UL BWP (by L1 signaling or MAC CE or RRC signaling, etc.). Or, switching to a determined DL/UL BWP may be performed when a timer value expires based on a timer. In this case, the activated DL/UL BWP is defined as an active DL/UL BWP. However, since the UE may not receive the configuration for the DL/UL BWP when the UE is performing an initial access procedure or before the RRC connection is set up, the DL/UL BWP assumed by the UE in such a situation is defined as an initially active DL/UL BWP.

FIG. 6 illustrates physical channels used in a wireless communication system to which the present disclosure can be applied and a general signal transmission and reception method using the same.

In a wireless communication system, a terminal receives information from a base station through a downlink, and the terminal transmits information to the base station through an uplink. The information transmitted and received by the base station and the terminal includes data and various control information, and various physical channels exist depending on the type/purpose of the information they transmit and receive.

When the terminal is powered on or enters a new cell, it performs an initial cell search operation such as synchronizing with the base station (S601). To this end, the terminal can receive a primary synchronization signal (PSS) and a secondary synchronization signal (PSS) from the base station to synchronize with the base station and obtain information such as a cell identifier (ID). Thereafter, the terminal can receive a physical broadcast channel (PBCH) from the base station to obtain broadcast information within the cell. Meanwhile, the terminal can receive a downlink reference signal (DL RS) in the initial cell search phase to check the downlink channel status.

A terminal that has completed an initial cell search can obtain more specific system information by receiving a physical downlink control channel (PDCCH) and a physical downlink shared channel (PDSCH) according to information carried on the PDCCH (S602).

Meanwhile, when accessing a base station for the first time or when there is no radio resource for signal transmission, the terminal may perform a random access procedure (RACH) for the base station (steps S603 to S606). To this end, the terminal may transmit a specific sequence as a preamble through a random access channel (RACH) (S603 and S605), and receive a response message to the preamble through a PDCCH and a corresponding PDSCH (S604 and S606). In case of a collision-based RACH, a contention resolution procedure may additionally be performed.

The terminal that has performed the procedure as described above can then perform PDCCH/PDSCH reception (S607) and physical uplink shared channel (PUSCH)/physical uplink control channel (PUCCH) transmission (S608) as general uplink/downlink signal transmission procedures. In particular, the terminal receives downlink control information (DCI) through the PDCCH. Here, the DCI includes control information such as resource allocation information for the terminal, and its format is different depending on the purpose of use.

Meanwhile, the control information that the terminal transmits to the base station via uplink or that the terminal receives from the base station includes downlink/uplink ACK/NACK (Acknowledgement/Non-Acknowledgement) signals, CQI (Channel Quality Indicator), PMI (Precoding Matrix Indicator), RI (Rank Indicator), etc. In the case of the 3GPP LTE system, the terminal can transmit the above-described control information such as CQI/PMI/RI via PUSCH and/or PUCCH.

Table 5 shows an example of DCI format in the NR system.

DCI format conjugation 0_0 Scheduling of PUSCH within a cell 0_1 Scheduling of one or multiple PUSCHs within a cell, or indicating cell group (CG) downlink feedback information to the UE. 0_2 Scheduling of PUSCH within a cell 1_0 Scheduling of PDSCH within a DL cell 1_1 Scheduling of PDSCH within a cell 1_2 Scheduling of PDSCH within a cell

Referring to Table 5, DCI formats 0_0, 0_1, and 0_2 may include resource information related to scheduling of PUSCH (e.g., UL/SUL (Supplementary UL), frequency resource allocation, time resource allocation, frequency hopping, etc.), transport block (TB) related information (e.g., MCS (Modulation Coding and Scheme), NDI (New Data Indicator), RV (Redundancy Version), etc.), HARQ (Hybrid - Automatic Repeat and request) related information (e.g., process number, DAI (Downlink Assignment Index), PDSCH-HARQ feedback timing, etc.), multi-antenna related information (e.g., DMRS sequence initialization information, antenna ports, CSI requests, etc.), power control information (e.g., PUSCH power control, etc.), and the control information included in each DCI format may be predefined. DCI format 0_0 is used for scheduling of PUSCH in one cell. Information included in DCI format 0_0 is transmitted with CRC (cyclic redundancy check) scrambled by C-RNTI (cell radio network temporary identifier, Cell RNTI) or CS-RNTI (Configured Scheduling RNTI) or MCS-C-RNTI (Modulation Coding Scheme Cell RNTI). DCI format 0_1 is used to indicate scheduling of one or more PUSCHs in one cell, or configure grant (CG) downlink feedback information to a UE. Information included in DCI format 0_1 is transmitted with CRC scrambled by C-RNTI or CS-RNTI or SP-CSI-RNTI (Semi-Persistent CSI RNTI) or MCS-C-RNTI.

DCI format 0_2 is used for scheduling PUSCH in a cell. Information included in DCI format 0_2 is transmitted CRC scrambled by C-RNTI or CS-RNTI or SP-CSI-RNTI or MCS-C-RNTI.

Next, DCI formats 1_0, 1_1, and 1_2 may include resource information related to scheduling of PDSCH (e.g., frequency resource allocation, time resource allocation, virtual resource block (VRB)-physical resource block (PRB) mapping, etc.), transport block (TB) related information (e.g., MCS, NDI, RV, etc.), HARQ related information (e.g., process number, DAI, PDSCH-HARQ feedback timing, etc.), multi-antenna related information (e.g., antenna port, transmission configuration indicator (TCI), sounding reference signal (SRS) request, etc.), PUCCH related information (e.g., PUCCH power control, PUCCH resource indicator, etc.), and control information included in each DCI format may be predefined.

DCI format 1_0 is used for scheduling PDSCH in one DL cell. Information included in DCI format 1_0 is transmitted CRC scrambled by C-RNTI or CS-RNTI or MCS-C-RNTI.

DCI format 1_1 is used for scheduling PDSCH in one cell. Information included in DCI format 1_1 is transmitted by CRC scrambled by C-RNTI or CS-RNTI or MCS-C-RNTI.

DCI format 1_2 is used for scheduling PDSCH in a cell. Information included in DCI format 1_2 is transmitted CRC scrambled by C-RNTI or CS-RNTI or MCS-C-RNTI.

Network energy saving (NES) method

Energy conservation at base stations can contribute to building eco-friendly networks by reducing carbon emissions and reducing operational expenditure (OPEX) for telecommunications industry players, which is an important consideration in wireless communication systems.

In particular, as wireless communication systems become more sophisticated, higher transmission rates are required, so base stations must be equipped with more antennas and provide services based on wider bandwidth and frequency bands. This is increasing the proportion of base station energy costs in the total OPEX of communication industry companies. Accordingly, interest in improving energy saving capabilities from the perspective of base station transmission and reception is increasing, and related technologies are being discussed.

For example, methods are discussed for achieving more efficient NES operation and fine-grained adaptation of transmission and/or reception with potential assistance/feedback from terminals and potential terminal assistance information, in relation to one or more network energy saving techniques in time, frequency, space and power domains.

Additionally, SCell operation without SSB for inter-band CA for FR1 and co-located cells is specified, and UEs can measure SSB transmitted from PCell or other SCells, if required, for SCell time/frequency synchronization and L1/L3 measurements, potential enhancements to SCell activation procedures, etc.

Additionally, in RRC_CONNECTED mode, cell DTX/DRX mode can be applied, including alignment of cell DTX/DRX and terminal DRX and exchange of information between nodes for cell DTX/DRX.

Additionally, CSI and beam management related procedures including measurement and reporting, signaling that enable efficient adaptation of spatial elements (e.g., antenna ports, active receiver chains, etc.) may be applied. And, CSI related procedures including measurement and reporting, signaling that enable efficient adaptation of power offset values between PDSCH and CSI-RS may be applied. Here, the object may be, but is not limited to, a terminal-specific channel/signal, and legacy terminal CSI/CSI-RS capabilities may be applied considering the number of total CSI reports and requirements.

Additionally, methods to prevent legacy terminal camping in cells where NES is applied, improved conditional handover (CHO) procedures when source/target cells are in NES mode, inter-node beam activation methods proposing paging in limited areas, and RRM/RF core requirement methods can be applied.

A base station can perform an operation to control a state (e.g., on/off) related to transmission and reception during a certain period (duration) in the time axis for NES purposes, control transmission and reception resources for terminal-common or terminal-specific signals/channels, change the amount of frequency-domain resources, control transmission power, or turn on/off an antenna port or TRP in the spatial domain. In describing the present disclosure, a state in which the above-described operation of the base station (hereinafter, NES operation (or NES technology)) is applied will be referred to as an NES mode or NES state.

The base station can instruct/configure the terminal for each NES mode (or NES mode group) that is actually applied among the above-described NES operation(s) (method 1). Additionally or alternatively, the base station can pre-configure the terminal for each corresponding NES operation (or NES mode group) for each code point of a specific indicator (method 2). In this case, the specific indicator can include an indicator indicated via DCI or MAC CE (etc.) and/or an indicator set by upper layer signaling.

For method 1, if at least one NES operation is applied to a terminal, the state of the terminal can be defined as a NES mode or a NES state. As another example, the terminal can be defined as being in a different NES mode or a different NES state depending on the NES operation applied to the terminal.

As an example, assume that there is an indicator (e.g., a 1-bit indicator) related to NES operation according to method 2. If the terminal is associated with one or more NES operations and the value of the indicator is set to "1", d may mean that the state of the terminal is in NES mode or NES state. As another example, if the value of the indicator is set to "0", it may mean that no NES operation is applied to the terminal.

As another example, assume that there is an indicator (e.g., a 2-bit indicator) related to NES operation according to method 2. If the indicator value (e.g., code point) is "00", this may mean that no NES operation is applied to the terminal. If the indicator values are "01", "10", or "11", respectively, this may mean that one or more NES operations applied/linked to the terminal are "NES_Operation A", "NES_Operation B", or "NES_Operation C", respectively. And, if the indicator values are "01", "10", or "11", respectively, this may mean that the terminal is "NES state #1", "NES state #2", or "NES state #3", respectively. That is, whether the terminal is in the NES state and/or information on the NES state of the terminal may be indicated/set for each code point according to the indicator.

Additionally or alternatively, the base station may turn on/off specific spatial elements for the NES and adjust power values for downlink signals/channels. Here, the spatial elements may mean or correspond to antenna port(s), active transceiver chains, panels or TRPs, etc.

To dynamically apply/instruct various NES operations/techniques in space and power domain, the base station may associate CSI-RS resources (sets) with different antenna ports for one CSI report setting configuration (e.g., "CSI-ReportConfig") or associate multiple power offsets (e.g., power offset between PDSCH and CSI-RS (e.g., "powerControlOffset" parameter), power offset between SSS and CSI-RS (e.g., "powerControlOffsetSS" parameter, etc.).

Specifically, at least one CSI framework described below may be applied.

CSI Framework #1: Multiple CSI-RS resource sets may be linked for one or more channel measurement resources (CMRs) or one or more interference measurement resources (IMRs) in a "CSI-ReportConfig" configuration. For example, CSI-RS resource set #1 and CSI-RS resource set #2 may be linked for CMR. Then, CSI-RS resources included in CSI-RS resource set #1 may be configured with 16 antenna ports, and CSI-RS resources included in CSI-RS resource set #2 may include 8 antenna ports.

CSI Framework #2: When there is a single CSI-RS resource set associated with one or more CMRs or one or more IMRs in a "CSI-ReportConfig" configuration, the CSI-RS resource set may include one or more CSI-RS resources with different properties (e.g., number of antenna ports and/or power offset, etc.). For example, 16 antenna ports may be configured (or power offset #1 value may be configured) for CSI-RS resource #1 included in CSI-RS resource set #1 configured with CMR, and 8 antenna ports may be configured (or power offset #2 value may be configured) for CSI-RS resource #2 included in the same CSI-RS resource set.

CSI Framework #3: If there is a CSI-RS resource set linked to one or more CMRs or one or more IMRs in a "CSI-ReportConfig configuration", the number of antenna ports and/or power offsets, etc., may be configured for some or all CSI-RS resource(s) in the CSI-RS resource set. For example, up to 16 antenna ports may be configured for CSI-RS resource #1 included in CSI-RS resource set #1 set to CMR, and at least one of the antenna ports may be configured for utilized CSI reporting. As another example, multiple power offset values may be configured for CSI-RS resource #2 included in the same CSI-RS set, and a CSI report may be configured for utilizing all or some of the multiple power offset values.

Here, CMR can be set by parameters related to resources for channel measurement, and IMR can be set by parameters related to CSI-IM or NZP-CSI-RS for interference.

A CSI reporting method can be established/defined through at least one of the options described below under at least one CSI framework described above.

Option #1: CSIs based on multiple numbers of antenna ports and/or multiple power offset values set in a single CSI report can all be included in a single CSI report. As another example, CSIs based on multiple numbers of antenna ports and/or multiple power offsets can be included in a single CSI report through configuration/instruction of the base station. In this case, the numbers of antenna ports and/or power offset values set/instructed by the base station can be a part of the numbers of antenna ports and/or power offset values set in the corresponding CSI report.

Option #2: Even if the number of multiple antenna ports and/or the number of multiple power offset values are set in a single CSI report, CSIs based on a single number of antenna ports and/or a single power offset can be included in a single CSI report through the configuration/instruction of the base station.

Option #3: Even if multiple AP counts and/or multiple power offset values are set in a single CSI report, CSIs based on some number of antenna ports and/or some power offsets can be included in a single CSI report through the terminal's judgment/decision (based on criteria pre-set by the base station or defined in advance).

For example, a "CSI-ReportConfig" configuration may have L (>1) sub-configurations configured/included, and each sub-configuration may correspond to one space or power domain adaptation pattern.

Here, the CSI-RS power value determined by the parameter related to the power offset value between SSS and CSI-RS (e.g., "powerControlOffsetSS"), if some antenna elements corresponding to one antenna port are turned off, this may affect the CSI-RS power value. Accordingly, the spatial domain adaptation pattern may correspond to a specific number of antenna ports (or, antenna port on/off pattern) or may correspond to a specific CSI-RS power value.

For example, assume a case where CSI framework #2 is applied. When the number of A1 antenna ports (or P1 power value) is set for CSI-RS index #n1 included in a CSI resource set and the number of A2 antenna ports (or P2 power value) is set for CSI-RS index #n2 included in the same CSI-RS resource set, sub-configuration index #s1 can be set to be linked to CSI-RS index #n1, and sub-configuration index #s2 can be set to be linked to CSI-RS index #n2. Accordingly, a spatial domain adaptation pattern can be set differently for each sub-configuration.

For example, assume a case where CSI framework #3 is applied. When the number of A1 antenna ports (or P1/P2 power values) is set for a CSI-RS index #n1 included in a CSI resource set, the number of A1 antenna ports (or P1 power value or delta 11 from the P1 power value) may be linked to the sub-configuration index #s1, and the number of A2 antenna ports (or P2 power value or delta 2 from the P1 power value), which is less than A1 constituting the CSI-RS index #n1, may be linked to the sub-configuration index #s2. Accordingly, a spatial domain adaptation pattern may be set differently for each sub-configuration. In addition, the spatial domain adaptation pattern may mean that a power offset value (e.g., a power offset value determined by a parameter related to a power offset between a PDSCH and a CSI-RS or/and a parameter related to a power offset between an SSS and a CSI-RS) is varied.

For example, assume a case where CSI framework #2 is applied. When a P1 power value is set for a CSI-RS index #n1 included in a CSI resource set and a P2 power value is set for a CSI-RS index #n2 included in the same CSI-RS resource set, the CSI-RS index #n1 may be linked to the sub-configuration index #s1, and the CSI-RS index #n2 may be linked to the sub-configuration index #s2. Accordingly, a power domain adaptation pattern may be set differently for each sub-configuration.

For example, assume a case where CSI framework #3 is applied. When a P1 power value (and a P2 power value) are set for a CSI-RS index #n1 included in a CSI resource set, the P1 power value may be linked for a sub-configuration index #s1, and the P2 power value (or a delta from the P1 power value) may be set to be linked for a sub-configuration index #s2. A different power domain adaptation pattern may be set for each sub-configuration. The terminal may feed back a CSI report composed of CSI information corresponding to N (N value 1 to L) sub-configurations (according to one of the methods of option #1/#2/#3) among the L sub-configurations to the base station.

That is, one CSI reporting configuration may contain one or more sub-configurations, and each sub-configuration may contain at least one of i) a list of IDs of one or more CSI-RS resource(s), ii) an antenna port subset indication consisting of a bitmap, and iii) an additional power offset delta from an EPRE offset between PDSCH and CSI-RS configured in the CSI-RS resource configuration.

In describing the present disclosure, a CSI reporting configuration including a sub-configuration in which an ID list of one or more CSI-RS resource(s) is set is referred to as Type 2 SD (spatial domain) adaptation. A CSI reporting configuration including a sub-configuration in which an antenna port subset indication consisting of a bitmap is set is referred to as Type 1 SD adaptation. A CSI reporting configuration including a sub-configuration in which an additional power offset delta value is set is referred to as PD (power domain) adaptation.

An ID list and/or power offset delta value of one or more CSI-RS resource(s) may be set for sub-configuration(s) included in one CSI reporting configuration, which is named as "Type 2 SD + PD adaptation". Antenna port subset indication and/or power offset delta value consisting of a bitmap may be set for sub-configuration(s) included in one CSI reporting configuration, which is named as "Type 1 SD + PD adaptation".

For Type 1 SD, PD or, "Type 1 SD + PD adaptation", each CSI-RS resource can be associated with all sub-configurations configured in one CSI reporting configuration respectively. For Type 2 SD, each CSI-RS resource can be associated with only a single sub-configuration among multiple sub-configurations in one CSI reporting configuration.

For "Type 2 SD + PD adaptation", the list #1 of CSI-RS resource(s) configured in a specific sub-configuration within the same CSI reporting configuration and the list #2 of CSI-RS resource(s) configured in another sub-configuration may be identical or disjoint.

As another example, when L sub-configurations are configured in one CSI reporting configuration, the UE can report CSI information corresponding to each of the L sub-configurations to the base station via one PUSCH/PUCCH. Only N (N value greater than or equal to 1 and less than or equal to L) sub-configurations among the L sub-configurations can be activated or triggered via MAC-CE or DCI. In this case, the UE can report CSI information corresponding to each of the N sub-configurations to the base station via one PUSCH/PUCCH.

Specifically, for a CSI reporting configuration in which semi-static CSI reporting over PUCCH is configured, N sub-configurations(s) out of L sub-configurations configured over MAC-CE can be activated. For a CSI reporting configuration in which semi-static CSI reporting over PUSCH or aperiodic CSI reporting is configured, N sub-configurations(s) out of L sub-configurations configured over DCI can be triggered.

On-demand SSB transmission and reception method for NES

From the perspective of a base station operating multiple frequency bands, even when the number of terminals served is small or the traffic load is relatively low, the energy consumption due to periodic transmission of SSB and/or system information can be large.

For example, as illustrated in FIG. 7, if a base station operating three frequency bands periodically transmits (legacy) SSB only on some frequency bands (e.g., F1) and transmits simplified (or modified) S(simplified)-SSB or no SSB on other frequency bands (e.g., F2 or/and F3), energy saving can be achieved. In describing the present disclosure, a frequency band can be replaced with a band, a carrier, a serving cell, or a BWP, and applied.

A terminal operating in F2 or F3 can request SSB transmission from a base station in the corresponding frequency band. In describing the present disclosure, an SSB transmitted by a base station at the request of a terminal is referred to as an on-demand SSB. The on-demand SSB may include a legacy SSB or/and a simplified (or modified) S-SSB. In addition, a cell in which an SSB is not transmitted or an S-SSB can be transmitted, such as F2 or F3 of FIG. 7, is referred to as an SSB-less cell. An SSB-less cell may be a PCell, a PScell (Primary Secondary Cell), or an SCell from the perspective of a terminal.

Below, the configuration information and related procedures for operating on-demand SSB in a cell without SSB are described. In this disclosure, '/' may mean 'and', 'or', or 'and/or' depending on the context.

FIG. 8 is a flowchart for explaining the operation of a terminal in a wireless communication system according to one embodiment of the present disclosure.

The terminal can receive first configuration information related to an on-demand synchronization signal for the first cell from the base station (S810).

Here, the first cell may be a primary cell or a secondary cell. The first configuration information may include at least one of information on whether to transmit an on-demand synchronization signal during a specific unit time, a size of the specific unit time, a transmission period of the on-demand synchronization signal, pattern information of the on-demand synchronization signal, a power value of the on-demand synchronization signal, or frequency information of the on-demand synchronization signal.

For example, if the first cell is a secondary cell, the terminal may receive third configuration information related to at least one secondary cell including the first cell from the base station. That is, the third configuration information may be upper layer signaling related to addition/configuration of at least one secondary cell. The third configuration information may include information related to whether the first cell is a cell through which an on-demand synchronization signal is transmitted and received.

For example, upper layer signaling including third configuration information may include first configuration information. That is, the first configuration information and the third configuration information may be transmitted to the terminal simultaneously. However, this is only an example, and the first configuration information and the third configuration information may be transmitted to the terminal separately.

Based on receiving an on-demand synchronization signal from a base station within a specific unit time, the terminal can transmit first information related to a first beam failure to the base station based on the on-demand synchronization signal (S820).

For example, if an on-demand synchronization signal is received from the base station through the first cell within a specific unit time, the terminal may perform a measurement operation for the on-demand synchronization signal with respect to the first cell, and perform a first beam failure detection operation according to the measurement result. Based on the detection of the first beam failure, the terminal may transmit first information related to the first beam failure to the base station.

The first information related to the first beam failure can be transmitted to the base station via (uplink) control information (e.g., MAC-CE, etc.). For example, the first information related to the first beam failure can include information about the first cell in which the first beam failure was detected (e.g., whether the first cell is a secondary cell or a special cell (or, primary cell)), information about a candidate beam/reference signal, etc. That is, a specific unit time at which an on-demand synchronization signal is transmitted can be set/determined based on the first setting information.

As an example of the present disclosure, based on not receiving an on-demand synchronization signal from the base station within a specific unit time, the terminal can transmit second information related to a second beam failure to the base station based on a reference signal.

Here, whether or not to transmit a reference signal of the base station can be determined depending on whether or not an on-demand synchronization signal is received within a specific unit time. For example, if the base station transmits an on-demand synchronization signal to the terminal (in the first cell) within a specific unit time, the reference signal may not be transmitted to the terminal, and thus, base station power consumption may be reduced. For example, the period of the on-demand synchronization signal may be shorter than the period of the reference signal. Accordingly, if the on-demand synchronization signal is transmitted from the base station to the terminal, reference signal transmission of the base station with a relatively long period may not be performed.

For example, the terminal may not receive an on-demand synchronization signal within a cell discontinuous transmission (DTX) inactive interval. That is, an on-demand synchronization signal may not be transmitted to the terminal during the DTX inactive interval. Additionally or alternatively, if a specific unit time overlaps with a DTX inactive interval, the terminal may not receive an on-demand synchronization signal from the base station within the DTX inactive interval (i.e., within the interval in which the specific unit time overlaps with the DTX inactive interval).

As described above, if an on-demand synchronization signal (from the first cell) is not transmitted to the terminal within a specific unit time, reference signal transmission of the base station may be performed. For example, the terminal may receive second configuration information for the reference signal from the base station. Here, the reference signal may include at least one of a channel state information (CSI) reference signal or another synchronization signal.

And, the reference signal can be transmitted to the terminal via the first cell or the second cell. For example, based on the first cell being a secondary cell (or a special cell or a primary cell), the second cell can be a special cell or a primary cell (or a secondary cell).

Based on the fact that the on-demand synchronization signal is not transmitted from the base station to the terminal within a specific unit time, the terminal may not generate the first information related to the first beam failure. For example, the terminal may not operate a beam counter related to the first beam failure (i.e., increase a beam counter value). Additionally or alternatively, the terminal (e.g., a physical layer of the terminal) may not forward a beam failure instance indication for the first beam failure to a higher layer (e.g., a MAC layer).

For example, the terminal may perform a beam failure detection operation based on a reference signal. Based on the detection of a second beam failure based on the reference signal, the terminal may transmit information related to the second beam failure to the base station. For example, the terminal may transmit the second information related to the second beam failure to the base station via (uplink) control information (e.g., MAC-CE, etc.).

For example, the second information associated with a second beam failure may include information about the second cell in which the beam failure was detected (e.g., whether the second cell is a secondary cell or a special cell (or primary cell)), information about a candidate beam/reference signal, etc.

In describing the present disclosure, the configuration information may be transmitted from the base station to the terminal via upper layer signaling (e.g., SIB, RRC, MAC-CE, etc.), but is not limited thereto. In addition, the configuration information may be transmitted to the terminal via the primary cell, but is not limited thereto, and may also be transmitted to the terminal via the secondary cell.

The method described in the example of FIG. 8 can be performed by the first device (100) of FIG. 1. For example, one or more processors (102) of the first device (100) of FIG. 1 can receive first configuration information related to an on-demand synchronization signal for a first cell from a base station through one or more transceivers (106). Based on receiving the on-demand synchronization signal from the base station within a specific unit time, the one or more processors (102) can transmit first information related to a first beam failure to the base station through one or more transceivers (106) based on the on-demand synchronization signal.

Furthermore, one or more memories (104) of the first device (100) may store instructions for performing the method described in the example of FIG. 8 or the examples described below when executed by one or more processors (102).

FIG. 9 is a flowchart for explaining the operation of a base station in a wireless communication system according to one embodiment of the present disclosure.

The base station can transmit first configuration information related to an on-demand synchronization signal for the first cell to the terminal (S910).

For example, the base station may transmit to the terminal first configuration information including various information for transmission of an on-demand synchronization signal. Additionally or alternatively, based on the first cell being a secondary cell, the base station may transmit to the terminal third configuration information related to at least one secondary cell including the first cell. Here, the third configuration information may include information related to whether the first cell is a cell through which the on-demand synchronization signal is transmitted and received. The base station may configure the on-demand synchronization signal for the terminal but may not transmit the on-demand synchronization signal.

Based on transmitting an on-demand synchronization signal to a terminal within a specific unit time, the base station can receive first information related to a first beam failure from the terminal based on the on-demand synchronization signal (S920).

Here, information about the time at which the base station transmits the on-demand synchronization signal (i.e., a specific unit time, etc.) can be set/indicated by the first setting information.

As another example, based on not transmitting an on-demand synchronization signal to the terminal, the base station can receive second information related to the second beam failure from the terminal based on the reference signal. As an example, the base station can transmit second configuration information for the reference signal to the terminal, and the reference signal can include CSI-RS or other SSB, etc. The reference signal can be transmitted to the terminal via the first cell or the second cell.

The method described in the example of FIG. 9 can be performed by the second device (200) of FIG. 1. For example, one or more processors (202) of the second device (200) of FIG. 1 can transmit first configuration information related to an on-demand synchronization signal for a first cell to a terminal through one or more transceivers (206). Based on transmitting the on-demand synchronization signal to the terminal within a specific unit time, the one or more processors (202) can receive first information related to a first beam failure from the terminal through one or more transceivers (206) based on the on-demand synchronization signal.

Furthermore, one or more memories (204) of the second device (200) may store instructions for performing the method described in the example of FIG. 9 or the examples described below when executed by one or more processors (202).

Below, the operating procedures of on-demand SSB in a non-SSB cell, the method for judging radio link failure based on the measurement results of a specific reference signal, and the RACH method for the second cell/TRP are described in detail.

As an example of the present disclosure, a terminal in RRC_IDLE or/and RRC_INACTIVE mode can determine a first cell as a serving cell through cell (re)selection and acquire system information from the first cell. A terminal in RRC_CONNECTED mode can acquire system information from the first cell or acquire system information through DCI, MAC CE, or terminal-only message transmitted by a base station.

The terminal can determine that the second cell or the second TRP is operating as an SSB-less cell or an SSB-less TRP through the acquired system information of the first cell (e.g., MIB, SIB1 or other SIBs, etc.) or the DCI/MAC CE/terminal-only message. Additionally or alternatively, the terminal can determine that the second cell or the second TRP supports the operation/configuration related to on-demand SSB through the acquired system information of the first cell or the DCI/MAC CE/terminal-only message.

At this time, an indicator indicating that the second cell/TRP supports SSB-less cell/TRP operation and/or on-demand SSB operation may be included in the system information or DCI/MAC CE/terminal only message of the first cell. Additionally or alternatively, the system information or DCI/MAC CE/terminal only message of the first cell may include an uplink transmission resource (e.g., PRACH resource/preamble) configuration requesting on-demand SSB for the second cell/TRP. Additionally or alternatively, the system information or DCI/MAC CE/terminal only message of the first cell may include a reference signal configuration mapped to the second cell/TRP or a reference signal configuration mapped to a specific on-demand SSB of the second cell/TRP or having a QCL relationship.

In describing the present disclosure, a reference signal may be an RS for a first cell/TRP or a second cell/TRP. Additionally or alternatively, the reference signal may be an RS mapped to a specific SSB (or, a specific SSB index) of the first cell/TRP or the second cell/TRP. A plurality of reference signals may be configured as one RS set, and each RS in the set may be indicated/configured/mapped with a different RS index. Different RS indices may be mapped or connected in a QCL relationship to different SSB indices of the first cell/TRP or the second cell/TRP.

When a reference signal for the second cell/TRP is set, a terminal supporting NES can perform layer-1 or layer-3 based measurement based on the reference signal. At this time, the reference signal can be SSB of the first cell/TRP or the second cell/TRP, CSI-RS, or a separate new RS. At this time, the terminal can trigger the above-described measurement if one or more of the following conditions are satisfied.

Condition 1: Whether the terminal supports SSB-less cell/TRP operation and/or on-demand SSB operation for NES.

Condition 2: Condition on whether the above measurement is set/indicated by an RRC release message indicating a transition from RRC_CONNECTED mode to RRC_IDLE or RRC_INACTIVE mode.

Condition 3: Condition on whether system information acquired from the terminal's serving cell(s) sets/instructs the above measurement.

Condition 4: Condition on whether the SSB (or CSI-RS) measurement for the first cell/TRP is below the threshold.

Condition 5: Condition on whether the frequency priority for the 2nd cell/TRP is higher than the frequency priority for the 1st cell/TRP.

Condition 6: Condition on whether RACH process failed in the first cell/TRP

Condition 7: Condition on whether RLF or beam failure occurred in the first cell/TRP

Condition 8: Condition on whether a command (e.g., a command transmitted via RRC message, MAC CE or DCI) has been received from the first cell/TRP instructing to perform measurements in the manner described above.

The terminal can perform uplink transmission (e.g., PRACH transmission) requesting on-demand SSB for the second cell/TRP in the first cell/TRP or the second cell/TRP according to uplink transmission resource configuration. Thereafter, the terminal can receive the on-demand SSB requested in the second cell/TRP. At this time, the terminal can map a specific uplink transmission resource (e.g., a specific PRACH resource/preamble) to one or more specific on-demand SSB indices, and different uplink transmission resources can be mapped to different on-demand SSB indices. In addition, a specific uplink transmission resource can be mapped to at least one of MIB, SIB1, SIBx (an integer where x > 1), or on-demand SSB, and can be configured to request at least one of them.

Additionally or alternatively, the terminal may trigger the RACH to request on-demand SSB, and may request at least one of MIB, SIB1, SIBx (where x is an integer > 1), on-demand SSB via RACH MSG3 or RACH MSGA. For example, the RACH MSG3 or/and RACH MSGA may transmit a UCI, MAC CE or RRC message. And, the UCI, MAC CE or RRC message may include an indicator requesting at least one of MIB, SIB1, SIBx (where x is an integer > 1), on-demand SSB.

For example, a UCI, MAC CE, or RRC message may include an indicator requesting an on-demand SSB and/or SSB index(es) corresponding to the SSB(s) to be requested. Additionally, the UCI, MAC CE, or RRC message may include at least one of an indicator indicating a MIB, an indicator indicating SIB1, an indicator indicating SIB2, and an indicator indicating SIB3. The UCI, MAC CE, or RRC message may include a bitmap composed of bits for each of the above indicators, and multiple bit strings may be composed following each of the indicators.

If at least one of the following conditions is satisfied, the terminal can perform uplink transmission requesting on-demand SSB.

Condition 1: Whether the measured value of the reference signal mapped to the second cell/TRP is higher than the measured value of the reference signal for the first cell/TRP (e.g., the cell defining the SSB) (e.g., whether the difference between the measured value of the reference signal mapped to the second cell/TRP and the reference signal for the first cell/TRP is greater than or equal to the offset value)

Condition 2: Condition on whether the measured value of the reference signal mapped to the 2nd cell/TRP is greater than or equal to the threshold value.

Condition 3: Condition on whether the measured value of the reference signal for the first cell/TRP (e.g., the cell defining the SSB) is below the threshold value.

Condition 4: Condition on whether the frequency of the reference signal mapped to the 2nd cell/TRP or the frequency for the 2nd cell/TRP has a higher priority than the frequency for the 1st cell/TRP.

Condition 5: Condition on whether the 2nd cell/TRP and the 1st cell/TRP are included in the same PLMN or an equivalent PLMN.

Condition 6: Condition on whether the second cell is determined to be a suitable cell for the terminal based on system information about the second cell/TRP obtained from the first cell/TRP.

Condition 7: Condition on whether the second cell is determined to be a suitable cell for the terminal based on system information about the second cell/TRP obtained from the first cell/TRP.

IDLE/INACTIVE terminals can receive on-demand SSB, MIB, SIB1, SIBx for the second cell, and perform cell reselection operation from the first cell to the second cell.

An IDLE/INACTIVE terminal can receive SIB1 to acquire RACH settings for the first cell or the second cell, and perform a RACH process with the first cell or the second cell to switch to the CONNECTED mode. At this time, the PCell or PSCell of the terminal can be the first cell or the second cell. Thereafter, before or after switching to the CONNECTED mode, the terminal can set the second cell (or the first cell) as an SCell in addition to the first cell (or the second cell), which is the PCell or PSCell.

An IDLE/INACTIVE/CONNECTED terminal can request at least one of on-demand SSB, MIB, SIB1, SIBx via uplink transmission and receive the requested data. Additionally or alternatively, the terminal can perform a separate uplink transmission requesting MIB, SIB1, SIBx after initially requesting on-demand SSB. Additionally or alternatively, the terminal can perform a separate uplink transmission requesting SIB1, SIBx after initially requesting on-demand SSB and MIB.

Accordingly, the terminal can receive all on-demand SSB, MIB, SIB1 and SIBx at once or sequentially with a single request. As another example, the terminal can sequentially request and receive each on-demand SSB, MIB, SIB1 and SIBx, or request and receive only a part of the data.

For example, if the second cell is configured as a SCell, the terminal can request and receive only on-demand SSB, and, if necessary, can request and receive on-demand SSB and MIB simultaneously in a single uplink transmission. As another example, if the second cell is configured as a PSCell, the terminal can request on-demand SSB and MIB simultaneously and receive the on-demand SSB and MIB. As another example, if the second cell is configured as a PCell, the terminal can request on-demand SSB and MIB/SIB1 simultaneously or sequentially and receive the on-demand SSB and MIB/SIB1, and then request and receive SIBx according to the on-demand SI setting of SIB1.

In describing the present disclosure, the first cell/TRP and the second cell/TRP may be the same or different. Additionally, the first TRP and the second TRP may belong to the same or different cells.

Example 1

Embodiment 1 relates to a method for determining whether a specific cell/TRP is an SSB-less cell/TRP and/or whether on-demand SSB is in operation based on the measurement results of a specific reference signal.

The terminal can measure reference signal(s) for the first cell/TRP or the second cell/TRP. The terminal can determine whether the second cell/TRP is an SSB-less cell/TRP or operates on-demand SSB based on whether the measured value (e.g., RSRP, RSRQ or RSSI) of the reference signal(s) is greater than or equal to a specified threshold. If it is determined that (the second cell/TRP) is operating on-demand SSB, the terminal can request on-demand SSB. If it is determined that (the second cell/TRP) is not operating, the terminal may not request on-demand SSB.

Here, the overall measurement value for the reference signal may be determined as an average value of measurement values for each RS index within the RS set constituting the reference signals, or an average value of measurement values for each RS index above a certain level within the RS set, or a best value (or worst value) of measurement values for each RS index within the RS set. The threshold may be set through system information of the first cell or a terminal-only message. For an IDLE/INACTIVE terminal, the terminal-only message may be an RRC release message.

As an example of the present disclosure, if the overall measurement value for the reference signal is greater than or equal to a threshold value, the terminal may determine that the on-demand SSB for the second cell/TRP is in operation or not in operation for all SSB indices. The terminal may perform at least one of the following operations.

- For example, if the measurement value for the reference signal is greater than or equal to the threshold, the terminal may determine that on-demand SSB for the second cell/TRP is in operation. Accordingly, if on-demand SSB transmission is not detected, the terminal may perform an operation of requesting on-demand SSB. If on-demand SSB transmission is detected, the terminal may not request on-demand SSB.

- For example, if the measurement value for the reference signal is greater than or equal to the threshold, the terminal may determine that SSB for the second cell/TRP is being transmitted and there is no need to request on-demand SSB.

- For example, if the measurement value for the reference signal is below the threshold, the terminal may determine that the on-demand SSB for the second cell/TRP is not in operation. Accordingly, the terminal may not request the on-demand SSB.

- For example, if the measurement value for the reference signal is below the threshold, the terminal can determine that SSB for the current second cell/TRP is not being transmitted and can request on-demand SSB.

As another example of the present disclosure, if an individual measurement value of a specific RS index is greater than or less than a threshold value, the terminal may determine that the on-demand SSB is in operation or not in operation for the SSB index mapped to the specific RS index of the second cell/TRP. The terminal may perform at least one of the following operations.

- For example, if an individual measurement value of a specific RS index is greater than or equal to a threshold value, the terminal may determine that on-demand SSB is in operation for the SSB index mapped to the specific RS index of the second cell/TRP. Accordingly, if on-demand SSB transmission is not detected, the terminal may request on-demand SSB for the corresponding SSB index. And, if on-demand SSB transmission is detected, the terminal may not request on-demand SSB for the corresponding SSB index.

- For example, if an individual measurement value of a specific RS index is greater than or equal to a threshold value, the terminal may determine that SSB is being transmitted for an SSB index mapped to a specific RS index of the second cell/TRP, and that there is no need to request an on-demand SSB for the SSB index.

- For example, if an individual measurement value of a specific RS index is below a threshold, the terminal may determine that on-demand SSB is not in operation for the SSB index mapped to the specific RS index for the second cell/TRP. Accordingly, the terminal may not request on-demand SSB for the corresponding SSB index.

- For example, if an individual measurement value of a specific RS index is below a threshold, the terminal may determine that SSB is not currently being transmitted for an SSB index mapped to the specific RS index of the second cell/TRP, and may request on-demand SSB for the SSB index.

As another example of the present disclosure, if the overall measurement value is greater than or less than a threshold value, the terminal may determine whether or not SSB for the second cell/TRP is transmitted for all SSB indices. The terminal may perform at least one of the following operations:

- For example, if the overall measurement value is greater than or equal to the threshold, the terminal may determine that SSB for the second cell/TRP is being transmitted and there is no need to request on-demand SSB.

- As another example, if the overall measurement value is below the threshold, the terminal may determine that SSB for the second cell/TRP is not being transmitted and may request on-demand SSB (if on-demand SSB is configured).

As another example of the present disclosure, if an individual measurement value of a specific RS index is greater than or less than a threshold value, the terminal may determine that the SSB index mapped to the specific RS index for the second cell/TRP is to be transmitted or not transmitted. The terminal may perform at least one of the following operations.

- For example, if the individual measurement value of a specific RS index is greater than or equal to a threshold value, the terminal may determine that the SSB index mapped to the specific RS index for the second cell/TRP is being transmitted. Accordingly, the terminal may determine that there is no need to request an on-demand SSB for the corresponding SSB index.

- For example, if an individual measurement value of a specific RS index is below a threshold, the terminal may determine that the SSB index mapped to the specific RS index for the second cell/TRP is not being transmitted. Accordingly, (if on-demand SSB is configured) the terminal may determine that on-demand SSB for the corresponding SSB index can be requested.

A base station that receives an on-demand SSB request from a terminal can transmit SSB(s) for the corresponding SSB index for the second cell/TRP or the entire SSB index to the terminal. At this time, the on-demand SSB transmission can be performed at a resource location where an existing SSB is transmitted or can be set to be performed at a separate opportunity.

Example 2

Example 2 relates to a method for determining beam failure per cell or per TRP based on the measurement results of a specific reference signal.

The base station may or may not separately set a reference signal according to the present disclosure for beam failure detection (and/or beam failure recovery request) for the terminal depending on whether SSB (or CSI-RS) transmission for the first cell/TRP or the second cell/TRP is performed. Accordingly, the terminal can perform beam failure detection (BFD) for the second cell/TRP based on the reference signal or the SSB/CSI-RS of the first cell/TRP.

Here, the second cell may be a SCell and the first cell may be a PCell/PSCell. As another example, the first cell may be a SCell and the second cell may be a PCell/PSCell. Additionally, the first TRP and the second TRP may belong to the same PCell/PSCell/SCell or may belong to different cells (PCell/PSCell/SCell).

As an example of the present disclosure, if the RS for BFD is not configured for the second cell/TRP, the terminal may determine beam failure based on the SSB/CSI-RS of the second cell/TRP. If the SSB/CSI-RS of the second cell/TRP is not configured (e.g., an SSB/CSI-RS-less cell/TRP) or the SSB/CSI-RS of the second cell/TRP is in a DTX inactive period (e.g., a TX off period), the terminal may determine beam failure for the second cell/TRP based on the reference signal or the SSB/CSI-RS of the first cell/TRP or the RS for BFD.

As an example of the present disclosure, if the RS for BFD is or is not set for the second cell/TRP and/or the activation BWP of the second cell/TRP does not include the SSB/CSI-RS or the RS for BFD of the second cell/TRP, the UE may determine beam failure for the second cell/TRP based on the reference signal or the SSB/CSI-RS or the RS for BFD of the first cell/TRP.

As an example of the present disclosure, if a RS for RLM is set for a second cell/TRP and/or if an RS for BFD and an SSB/CSI-RS of the second cell/TRP are in a DTX inactive interval for NES, the terminal may determine beam failure for the second cell/TRP based on a reference signal or an SSB/CSI-RS of the first cell/TRP or an RS for BFD only in the DTX inactive interval. Here, if the RS for BFD or the SSB/CSI-RS of the second cell/TRP is in a DTX active interval, the terminal may determine beam failure for the second cell/TRP based on the RS for BFD for the second cell/TRP or the SSB/CSI-RS of the second cell/TRP. As another example, when the DTX enable/disable operation is set for the second cell/TRP, the terminal can determine beam failure for the second cell/TRP based on the reference signal, SSB/CSI-RS of the first cell/TRP, or RS for BFD regardless of the DTX enable/disable section.

The physical layer of the terminal may determine beam failure for the second cell/TRP according to the above-described operation and report information about the beam failure (e.g., beam failure instance indication) to the MAC layer of the terminal.

When the MAC layer of the terminal receives a beam failure instance indication from the terminal physical layer, the terminal may increase the BFI-COUNTER for the second cell/TRP (e.g., for the RS for BFD for the second cell/TRP) by one. For example, if the BFI_COUNTER value for the second cell/TRP is equal to or greater than a maximum value (e.g., "beamFailureInstanceMaxCount"), the terminal may trigger BFR (beam failure recovery) for the second cell/TRP (e.g., for the RS for BFD for the second cell/TRP). If BFR for the second cell/TRP is triggered, the terminal may transmit BFR MAC CE over PUSCH, or transmit SR (Scheduling Request) for BFR over PUCCH to the base station. In this case, the BFR MAC CE may indicate the second cell/TRP. Additionally, PUCCH SR can be an SR transmission via PUCCH resources mapped to BFR for the first cell/TRP or the second cell/TRP.

Below, additional or alternative operations to the above-described method are described.

- As an example of the present disclosure, it is assumed that a terminal determines a beam failure for a second cell/TRP based on an SSB (or CSI-RS) and/or an SSB (or CSI-RS) for the first cell/TRP or the second cell/TRP is not transmitted (e.g., the SSB (or CSI-RS) is not transmitted because it is included in a DTX deactivation interval). In this case, even if a beam failure instance indication of a physical layer for the second cell/TRP (e.g., an RS for BFD for the second cell/TRP) is not transmitted to the MAC layer or a beam failure instance indication of the physical layer is received, the terminal may not increase a BFI-COUNTER in the MAC layer during the DTX deactivation interval. In this case, the DTX deactivation interval is a DTX deactivation interval for the first cell/TRP or the second cell/TRP.

- As an example of the present disclosure, if there is no separate BFD-RS setting or reference RS in the second cell/TRP, the terminal may determine beam failure based only on the SSB (or BFD-RS) of the reference cell for all sections for the second cell/TRP. In this case, the reference cell/TRP may be the first cell/TRP or the third cell/TRP.

- As an example of the present disclosure, if there is no separate BFD-RS configuration or reference RS in the second cell/TRP, the terminal may not perform beam failure instance indication and/or BFI-COUNT of the physical layer for the second cell/TRP. In this case, if a reference cell/TRP of the second cell/TRP is designated and BFR of the reference cell/TRP is triggered, the terminal may operate as if BFR for the second cell/TRP is also triggered, and may report BFR MAC CE or trigger SR for BFR.

Accordingly, the terminal can report both the BFR of the second cell/TRP and the BFR of the reference cell/TRP to the base station via the BFR MAC CE. As another example, if the terminal reports only the BFR of the reference cell/TRP, the base station can consider that the BFR of the second cell/TRP has also been reported. Additionally, if the SR for BFR is triggered and the SR is transmitted to the base station, the terminal can report both the BFR of the second cell/TRP and the BFR of the reference cell/TRP to the base station. As another example, the terminal can report only the BFR of the reference cell/TRP to the base station, and the base station can consider that the BFR of the second cell/TRP has also been reported. In this case, the reference cell may be the first cell/TRP or the third cell/TRP.

Example 3

Example 3 relates to a RACH method for the second cell/TRP.

In the present disclosure, the UE can perform RACH for the second cell/TRP. For example, the UE can perform RACH for reasons such as PDCCH order, UL time alignment, SR or mobility. As another example, the UE can perform RACH to request on-demand SSB or system information for the second cell/TRP. In addition, if a Beam failure instance indication value for the second cell/TRP is greater than or equal to a maximum value (e.g., when the second cell/TRP is an SCell), the UE can report BSR MAC CE or PUCCH SR, or trigger RACH (e.g., when the second cell/TRP is a PCell/PSCell).

At this time, BSR MAC CE, PUCCH SR, or RACH transmission for the second cell/TRP can be performed in the first cell/TRP, the second cell/TRP, or the third cell/TRP. In addition, PRACH resource transmission of the first cell/TRP, the second cell/TRP, or the third cell/TRP can be performed for BSR MAC CE transmission. Accordingly, the terminal can transmit BSR MAC CE via RACH MSG3 or MSBA message. At this time, the first cell can be PCell/PSCell, and the second cell and the third cell can be SCell. As another example, the second cell can be PCell/PSCell, and the first cell and the third cell can be SCell.

The first TRP and the second TRP and the third TRP may be the same PCell/PSCell or SCell. In another example, two or more of the first TRP, the second TRP, and the third TRP may belong to the same or different PCell/PSCell or SCell. For this RACH operation, the first cell/TRP or the third cell/TRP may be set as a reference cell/TRP for the second cell/TRP.

Assume that RACH is triggered to request on-demand SSB or system information for a second cell/TRP, to report/recover beam failure for the second cell/TRP, or to trigger RACH due to reasons such as PDCCH order, UL time alignment, SR or mobility in the second cell/TRP. In this case, if the PRACH resource of the second cell/TRP is configured, RACH can be performed with the PRACH resource of the second cell/TRP, and if the PRACH resource of the second cell/TRP is not configured, RACH can be performed with the PRACH resource of the first cell/TRP or the third cell/TRP belonging to the same TAG (timing advance group) as the second cell. As another example, RACH can be performed with the first cell/TRP, which is always a PCell/PSCell (or designated for RACH).

When performing RACH with PRACH resources of the second cell/TRP for the reasons described above, the terminal may perform at least one of the operations described below.

- When SSB (or CSI-RS) is transmitted for a cell/TRP (e.g., 2nd cell/TRP) belonging to a PRACH resource, the terminal can measure the SSB (or CSI-RS) and select a PRACH resource to transmit.

- If SSB (or CSI-RS) for a cell/TRP (e.g., 2nd cell/TRP) belonging to a PRACH resource is available but is not being transmitted during the DTX inactive period, the terminal may select a PRACH resource and transmit by measuring the SSB (or CSI-RS) of the 1st cell/TRP or 3rd cell/TRP or the reference signal of the present disclosure during the DTX inactive period.

- If the SSB (or CSI-RS) for a cell/TRP (e.g., the second cell/TRP) belonging to the PRACH resource is not available and is not being transmitted due to an on-demand SSB or SSB-less cell/TRP, the UE may select a PRACH resource by measuring the SSB (or CSI-RS) of the first cell/TRP or the third cell/TRP or the reference signal of the present disclosure and transmit.

- For the above-described operations, the terminal may set a mapping relationship for the SSB (or CSI-RS) of the second cell/TRP and the SSB (or CSI-RS) of the first cell/TRP or the third cell/TRP by beam index. For example, the base station may set the SSB index #k of the first cell/TRP or the third cell/TRP and the SSB index #m of the second cell/TRP to be mapped to a QCL relationship, and may transmit this setting to the terminal through system information or a terminal-only message. If the measured value for the SSB index #k of the first cell/TRP or the third cell/TRP is equal to or greater than a threshold value, the terminal may select and transmit a PRACH resource/preamble for the SSB index #m of the second cell/TRP.

- (If there is no separate mapping setting) The terminal may select a PRACH resource assuming that the directions of the beam indices for the SSB (or CSI-RS) of the second cell/TRP and the SSB (or CSI-RS) of the first cell/TRP or the third cell/TRP are the same. For example, if the SSB index #k of the second cell/TRP and the SSB index #k of the first cell/TRP or the third cell/TRP are assumed to have a QCL relationship with each other, if the measured value for the SSB index #k of the first cell/TRP or the third cell/TRP is equal to or greater than a threshold value, the terminal may select and transmit a PRACH resource/preamble for the SSB index #k of the second cell/TRP.

As an example of the present disclosure, when performing RACH with PRACH resources of the first cell/TRP or the third cell/TRP for reasons such as the second cell/TRP, the terminal may perform at least one of the operations described below.

- As an example of the present disclosure, it is assumed that i) there is an SSB (or CSI-RS) for a second cell/TRP, ii) there is no SSB (or CSI-RS) for the second cell/TRP and there is an SSB (or CSI-RS) for a cell/TRP (e.g., 1 or 3) belonging to a PRACH resource, iii) there is an SSB (or CSI-RS) for the second cell/TRP but there is an SSB (or CSI-RS) for a cell/TRP (e.g., 1 or 3) belonging to a PRACH resource.

-- At this time, if SSB (or CSI-RS) for the second cell/TRP is transmitted, the terminal can measure the SSB (or CSI-RS) and select a PRACH resource as the PRACH resource of the first cell/TRP or the third cell/TRP to transmit.

-- If the SSB (or CSI-RS) for the second cell/TRP is available but is not being transmitted during the DTX deactivation interval, the terminal may select a PRACH resource to transmit by measuring the SSB (or CSI-RS) of the first cell/TRP or the third cell/TRP or the reference signal of the present disclosure during the DTX deactivation interval (or always regardless of DTX deactivation/activation).

-- If the SSB (or CSI-RS) for the second cell/TRP is not available and is not being transmitted (due to on-demand SSB or SSB-less cell/TRP), the terminal may select a PRACH resource by measuring the SSB (or CSI-RS) of the first cell/TRP or the third cell/TRP or the reference signal of the present disclosure and transmit.

- For the above-described operations, the terminal may set a mapping relationship for the SSB (or CSI-RS) of the second cell/TRP and the SSB (or CSI-RS) of the first cell/TRP or the third cell/TRP by beam index. For example, the base station may set the SSB index #k of the first cell/TRP or the third cell/TRP and the SSB index #m of the second cell/TRP to be mapped to a QCL relationship, and may transmit the above-described setting to the terminal via system information or a terminal-only message. If the measured value for the SSB index #k of the second cell/TRP is equal to or greater than a threshold value, the terminal may select and transmit a PRACH resource/preamble for the SSB index #m of the first or third cell/TRP.

- (If there is no separate mapping setting) The terminal may select a PRACH resource assuming that the directions of the beam indices for the SSB (or CSI-RS) of the second cell/TRP and the SSB (or CSI-RS) of the first cell/TRP or the third cell/TRP are the same. For example, the SSB index #k of the second cell/TRP and the SSB index #k of the first cell/TRP or the third cell/TRP are assumed to have a QCL relationship with each other, and if the measured value for the SSB index #k of the second cell/TRP is equal to or greater than a threshold value, the terminal may select and transmit a PRACH resource/preamble for the SSB index #k of the first or third cell/TRP.

Example 4

Example 4 relates to a method of operating an SSB-less cell and an on-demand SSB.

A base station can configure/indicate that a particular serving cell is an SSB-less cell and/or a cell operating on-demand SSB (cell-common, cell-specific, terminal group-common or terminal-specific) via RRC message, MAC-CE or DCI.

If the UE identifies that a particular serving cell is an SSB-less cell and/or operates on-demand SSB through the reception of the setting/instruction, the UE may not expect SSB reception through the particular serving cell and may transmit an uplink signal/channel set for on-demand SSB purposes for SSB requests from the serving cell.

Specifically, for SCell, the information (e.g., information indicating that a specific serving cell is an SSB-less cell and/or an on-demand SSB-operating cell) can be conveyed via RRC signaling and/or SCell activation MAC-CE that configures and/or adds the SCell. For example, the base station can inform the UE that the SCell is an SSB-less cell and that the on-demand SSB-operating cell is a SSB-less cell when configuring and/or adding the SCell via RRC signaling.

As another example, the base station can configure and/or add a cell via RRC signaling while indicating that the SCell is an SSB-less cell and may be operating on-demand SSB. Additionally, the base station can indicate via MAC-CE that the cell is actually an SSB-less cell and/or a cell operating on-demand SSB.

When a SCell is activated and configured/indicated as an SSB-less cell and/or an on-demand SSB operating cell by the signaling described above, SSB can be transmitted on the SCell during a period of time T (the T value can be predefined or a value configured by the base station). Additionally or alternatively, whether SSB is to be transmitted during the period of time T can be predefined or can be explicitly configured/indicated by RRC signaling or (SCell activation) MAC-CE.

A reference cell (ref-cell) corresponding to an SSB-less cell may need to be configured, and one or more candidates for the reference cell may be configured. Which cell is actually the reference cell can be configured/indicated via RRC signaling or MAC-CE (indicating activation) that configures or adds the corresponding SSB-less cell.

As an example of the present disclosure, different cells may be linked depending on the function of the reference cell. For example, cell #A may be set/indicated as a reference cell for the purpose of timing synchronization and AGC setting of an SSB-less cell. Cell #B may be set/indicated as a reference cell for the purpose of UL power control (or path-loss estimation). Cell #C may be set/indicated as a reference cell for the purpose of performing RRM measurement instead. Alternatively, multiple reference cells may be set/indicated for the same function.

For example, when 2 TAs (timing advances) are configured for an SSB-less SCell (e.g., in a multi-TRP situation or in IAB operation), a reference cell for timing synchronization (and/or AGC setting) corresponding to each TA can be configured/indicated separately.

As another example, the reference cell (and/or DL signal/channel transmitted from the reference cell) for reference purposes of UL power control (or path-loss estimation) may be set differently depending on the UL signal/channel on the SSB-less cell.

As another example, different reference cells (and/or DL signals/channels transmitted from the reference cells) may be set differently depending on the measurement type. Specifically, for RSRP, SSB on cell #1 may be set as a reference, and for L1-SINR, SSB or CSI-RS resources on cel l#2 (or cell#1) may be set as a reference.

For one SSB-less cell, more than one reference cell can be linked/configured/instructed. At this time, a priority order may be required regarding which of the multiple linked reference cells will obtain timing synchronization, AGC setting, UL power control (or path-loss estimation), beam management-related measurement, or RRM measurement functions.

The priority order may be explicitly set/indicated, or the priority order may be determined by cell index (either ascending or descending). As another example, if the reference cell is inactive or a dormant BWP is running, even if the priority order is high, the cell corresponding to the next priority order may be replaced as the reference-cell.

Such priority order can also be set/defined at signal/channel level rather than cell level. For example, SSB of PCell, CSI-RS (e.g., TRS) of PCell and CSI-RS (e.g., TRS) of SCell can be set as reference for timing synchronization of SSB-less SCell (and/or for path-loss estimation). And, SSB of PCell can be set/indicated as having the highest priority and CSI-RS of SCell can be set/indicated as having the lowest priority or a rule can be set in advance.

A common reference cell may be set/indicated for multiple SSB-less SCells, and for this purpose, the SSB-less SCells may be grouped. For example, when SCell indices #0/1/2 are all set/indicated as SSB-less SCells and belong to the same group, the reference cells corresponding to the SCells belonging to the same group may be common. Specifically, when a reference cell is set/indicated for one of the SCells belonging to the same group, it may mean that the corresponding reference cell is automatically set/indicated as a reference cell from other SCells in the same group.

Even if a reference cell corresponding to a specific SSB-less SCell (or the group to which the SCell belongs) is not configured, a default reference cell can be determined by a rule. If the SSB-less SCell belongs to the master cell group (MCG), the default reference cell can be the PCell. If the SSB-less SCell belongs to the secondary cell group (SCG), the default reference cell can be the PSCell.

Additionally or alternatively, if an SSB-less SCell does not belong to a primary timing advance group (pTAG) but belongs to a secondary timing advance group (sTAG), any non-SSB-less SCell belonging to the same sTAG can be the default reference cell. Alternatively, the serving cell with the lowest/highest index cell index can be the default reference cell.

In order to minimize the system performance degradation due to the operation of SSB-less cells, SSB-less cell operation may not be allowed for PCell, PSCell, PUCCH-SCell (SCell on which PUCCH transmission is configured), or/and PUCCH-sSCell (e.g., SCell on which PUCCH can be transmitted due to PUCCH cell switching) on which PUCCH can be transmitted. As another example, a SCell configured/indicated as a reference cell of an SSB-less cell may not be allowed to be deactivated or operate as a sleep BWP.

For an on-demand SSB that can be transmitted on an SSB-less cell, at least one of the information described below for the terminal may be set. At least one of the information described below set for the terminal may be set differently for each BWP set in the SSB-less cell or may be set commonly for BWPs.

Multiple candidate values for one of the information described below can be defined/set in advance. One of the candidate values can be set/indicated via RRC signaling for setting/adding an SSB-less cell or MAC-CE (for SCell activation).

- On-Demand SSB Period: This can mean the (minimum) time interval during which the same SSB (candidate) index is transmitted. If the On-Demand SSB Period is not set, a default value (e.g., 20 msec) can be predefined or the SSB Period set in the reference cell can be applied as the On-Demand SSB Period on the SSB-less cell.

- Transmission duration of on-demand SSB: The transmission duration of on-demand SSB can mean the period from the start to the end of on-demand SSB transmission on an SSB-less cell. For example, it is assumed that on-demand SSB is transmitted P times with a cycle of X msec from slot #n in an SSB-less cell, and then SSB is no longer transmitted and is turned off from slot #n+k. In this case, k slots (or, absolute time corresponding to k slots or P) can be defined as a period.

- Pattern information for on-demand SSB: When the time/frequency structure may be different between legacy SSB and on-demand SSB, information on the pattern of compact/simplified SSB can be set.

- Power value of on-demand SSB: If path loss estimation, CSI reporting, etc. are performed via on-demand SSB, the power value of SSB may be required. If the power value of SSB is not set, a predefined default value may be applied or the SSB power value set in the reference cell may be inherited and applied. In addition, if the relative EPRE value between PSS, SSS, or/and PBCH may be different from the existing SSB, the relative EPRE value may also be additionally set.

- Location of frequency resources (e.g. center frequency) where on-demand SSB is transmitted.

- Information on whether the on-demand SSB is a NCD-SSB (non-cell defining-SSB) or a CD-SSB (cell defining-SSB).

- In case multiple ref-cells can be set for an SSB-less cell, the corresponding above-described information can be set separately for each reference cell.

Additionally, the above-described information can be set for SSB transmitted for a certain period of time T after SCell activation, as in Example 2.

Through the embodiments described above, the terminal and the base station can transmit and receive on-demand SSB. Depending on the measurement result of the on-demand SSB, cell deactivation or release can be performed, and thus, energy of the terminal and the base station can be saved.

General description of devices to which the present disclosure may be applied

FIG. 10 illustrates a block diagram of a wireless communication device according to one embodiment of the disclosure.

Referring to FIG. 10, the first device (100) and the second device (200) can transmit and receive wireless signals through various wireless access technologies (e.g., LTE, NR).

A first device (100) includes one or more processors (102) and one or more memories (104), and may additionally include one or more transceivers (106) and/or one or more antennas (108). The processor (102) controls the memories (104) and/or the transceivers (106), and may be configured to implement the descriptions, functions, procedures, suggestions, methods, and/or operational flowcharts disclosed in this disclosure.

For example, the processor (102) may process information in the memory (104) to generate first information/signal, and then transmit a wireless signal including the first information/signal through the transceiver (106). In addition, the processor (102) may receive a wireless signal including second information/signal through the transceiver (106), and then store information obtained from signal processing of the second information/signal in the memory (104).

The memory (104) may be connected to the processor (102) and may store various information related to the operation of the processor (102). For example, the memory (104) may perform some or all of the processes controlled by the processor (102), or may store software codes including commands for performing the descriptions, functions, procedures, proposals, methods, and/or operational flowcharts disclosed in the present disclosure. Here, the processor (102) and the memory (104) may be part of a communication modem/circuit/chip designed to implement a wireless communication technology (e.g., LTE, NR). The transceiver (106) may be connected to the processor (102) and may transmit and/or receive wireless signals via one or more antennas (108). The transceiver (106) may include a transmitter and/or a receiver. The transceiver (106) may be used interchangeably with an RF (Radio Frequency) unit. In the present disclosure, a device may also mean a communication modem/circuit/chip.

The second device (200) includes one or more processors (202), one or more memories (204), and may additionally include one or more transceivers (206) and/or one or more antennas (208). The processor (202) may control the memories (204) and/or the transceivers (206), and may be configured to implement the descriptions, functions, procedures, suggestions, methods, and/or operational flowcharts disclosed in this disclosure. For example, the processor (202) may process information in the memory (204) to generate third information/signal, and then transmit a wireless signal including the third information/signal via the transceiver (206). Additionally, the processor (202) may receive a wireless signal including fourth information/signal via the transceiver (206), and then store information obtained from signal processing of the fourth information/signal in the memory (204). The memory (204) may be connected to the processor (202) and may store various information related to the operation of the processor (202). For example, the memory (204) may perform some or all of the processes controlled by the processor (202), or may store software codes including commands for performing the descriptions, functions, procedures, proposals, methods, and/or operational flowcharts disclosed in the present disclosure. Here, the processor (202) and the memory (204) may be part of a communication modem/circuit/chip designed to implement wireless communication technology (e.g., LTE, NR). The transceiver (206) may be connected to the processor (202) and may transmit and/or receive wireless signals via one or more antennas (208). The transceiver (206) may include a transmitter and/or a receiver. The transceiver (206) may be used interchangeably with an RF unit. In the present disclosure, a device may also mean a communication modem/circuit/chip.

Hereinafter, hardware elements of the device (100, 200) will be described in more detail. Although not limited thereto, one or more protocol layers may be implemented by one or more processors (102, 202). For example, one or more processors (102, 202) may implement one or more layers (e.g., functional layers such as PHY, MAC, RLC, PDCP, RRC, SDAP). One or more processors (102, 202) may generate one or more Protocol Data Units (PDUs) and/or one or more Service Data Units (SDUs) according to the descriptions, functions, procedures, proposals, methods, and/or operational flowcharts disclosed in the present disclosure. One or more processors (102, 202) may generate messages, control information, data, or information according to the descriptions, functions, procedures, proposals, methods, and/or operational flowcharts disclosed in the present disclosure. One or more processors (102, 202) can generate signals (e.g., baseband signals) including PDUs, SDUs, messages, control information, data or information according to the functions, procedures, suggestions and/or methodologies disclosed in this disclosure, and provide the signals to one or more transceivers (106, 206). One or more processors (102, 202) can receive signals (e.g., baseband signals) from one or more transceivers (106, 206) and obtain PDUs, SDUs, messages, control information, data or information according to the descriptions, functions, procedures, suggestions, methods and/or operational flowcharts disclosed in this disclosure.

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

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

One or more transceivers (106, 206) can transmit user data, control information, wireless signals/channels, etc., as described in the methods and/or flowcharts of the present disclosure, to one or more other devices. One or more transceivers (106, 206) can receive user data, control information, wireless signals/channels, etc., as described in the descriptions, functions, procedures, suggestions, methods and/or flowcharts of the present disclosure, from one or more other devices. For example, one or more transceivers (106, 206) can be coupled to one or more processors (102, 202) and can transmit and receive wireless signals. For example, one or more processors (102, 202) can control one or more transceivers (106, 206) to transmit user data, control information, or wireless signals to one or more other devices. Additionally, one or more processors (102, 202) may control one or more transceivers (106, 206) to receive user data, control information, or wireless signals from one or more other devices. Additionally, one or more transceivers (106, 206) may be coupled to one or more antennas (108, 208), and one or more transceivers (106, 206) may be configured to transmit and receive user data, control information, wireless signals/channels, and the like, as described in the description, function, procedure, proposal, method, and/or operational flowchart, etc. disclosed in this disclosure, via one or more antennas (108, 208). In the present disclosure, one or more antennas may be multiple physical antennas, or multiple logical antennas (e.g., antenna ports). One or more transceivers (106, 206) may convert received user data, control information, wireless signals/channels, etc. from RF band signals to baseband signals in order to process the received user data, control information, wireless signals/channels, etc. using one or more processors (102, 202). One or more transceivers (106, 206) may convert processed user data, control information, wireless signals/channels, etc. from baseband signals to RF band signals using one or more processors (102, 202). For this purpose, one or more transceivers (106, 206) may include an (analog) oscillator and/or filter.

The embodiments described above are combinations of components and features of the present disclosure in a given form. Each component or feature should be considered optional unless explicitly stated otherwise. Each component or feature may be implemented in a form that is not combined with other components or features. In addition, it is also possible to combine some components and/or features to form an embodiment of the present disclosure. The order of operations described in the embodiments of the present disclosure may be changed. Some components or features of one embodiment may be included in another embodiment, or may be replaced with corresponding components or features of another embodiment. It is obvious that claims that do not have an explicit citation relationship in the scope of the patent may be combined to form an embodiment or may be included as a new claim by post-application amendment.

It will be apparent to those skilled in the art that the present disclosure may be embodied in other specific forms without departing from the essential characteristics of the present disclosure. Accordingly, the above detailed description should not be construed as limiting in all respects but should be considered as illustrative. The scope of the present disclosure should be determined by a reasonable interpretation of the appended claims, and all changes within the equivalent scope of the present disclosure are intended to be included in the scope of the present disclosure.

The scope of the present disclosure includes software or machine-executable instructions (e.g., an operating system, an application, firmware, a program, etc.) that cause operations according to the various embodiments to be executed on a device or a computer, and a non-transitory computer-readable medium having such software or instructions stored thereon and executable on the device or computer. Instructions that can be used to program a processing system to perform the features described in the present disclosure can be stored on/in a storage medium or a computer-readable storage medium, and a computer program product including such a storage medium can be used to implement the features described in the present disclosure. The storage medium can include, but is not limited to, high-speed random access memory, such as DRAM, SRAM, DDR RAM, or other random access solid state memory devices, and can include non-volatile memory, such as one or more magnetic disk storage devices, optical disk storage devices, flash memory devices, or other non-volatile solid state storage devices. The memory optionally includes one or more storage devices remotely located from the processor(s). The memory or alternatively the non-volatile memory device(s) within the memory comprises a non-transitory computer-readable storage medium. The features described in this disclosure may be incorporated into software and/or firmware stored on any one of the machine-readable media to control the hardware of the processing system and to allow the processing system to interact with other mechanisms that utilize results according to embodiments of the present disclosure. Such software or firmware may include, but is not limited to, application code, device drivers, operating systems, and execution environments/containers.

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

The method proposed in this disclosure has been described with a focus on examples applied to 3GPP LTE/LTE-A and 5G systems, but can be applied to various wireless communication systems in addition to 3GPP LTE/LTE-A and 5G systems.

Claims (15)

A step of receiving, by the terminal, first configuration information related to an on-demand synchronization signal for the first cell from the base station; and A step of transmitting, by the terminal, to the base station first information related to a first beam failure based on the on-demand synchronization signal, based on receiving the on-demand synchronization signal from the base station within a specific unit time, Based on not receiving the on-demand synchronization signal from the base station, second information related to a second beam failure based on a reference signal is transmitted by the terminal to the base station, A method wherein the specific unit time is based on the first setting information. In the first paragraph, Second setting information for the above reference signal is transmitted from the base station to the terminal, A method wherein the reference signal comprises at least one of a channel state information (CSI) reference signal or another synchronization signal. In the first paragraph, A method in which whether or not to transmit the reference signal of the base station is determined based on whether or not the on-demand synchronization signal is received within the specific unit time. In the first paragraph, A method wherein the on-demand synchronization signal is not transmitted from the base station to the terminal during a cell discontinuous transmission (DTX) inactive period. In the first paragraph, A method wherein the first information related to the first beam failure is not generated by the terminal based on the on-demand synchronization signal not being transmitted from the base station to the terminal within the specific unit time. In paragraph 5, A method wherein a beam counter associated with the first beam failure is not incremented or a beam failure instance indication for the first beam failure is not transmitted. In the first paragraph, A method in which information related to the first beam failure or information related to the second beam failure is transmitted from the terminal to the base station via control information. In the first paragraph, A method according to claim 1, wherein the first setting information includes at least one of information on whether to transmit the on-demand synchronization signal during the specific unit time, the size of the specific unit time, the transmission period of the on-demand synchronization signal, pattern information of the on-demand synchronization signal, power value of the on-demand synchronization signal, or frequency information of the on-demand synchronization signal. In the first paragraph, The first beam failure or the second beam failure includes a beam failure for the first cell, The above reference signal includes a reference signal for the first cell or the second cell, A method wherein the second cell is a primary cell, based on the first cell being a secondary cell. In Article 9, Based on the first cell being a secondary cell, third configuration information related to at least one secondary cell including the first cell is transmitted from the base station to the terminal, A method wherein the third setting information includes information related to whether the first cell is a cell through which the on-demand synchronization signal is transmitted and received. In the terminal, the terminal: one or more transceivers; and comprising one or more processors coupled to said one or more transceivers; One or more of the above processors: Receiving first configuration information related to an on-demand synchronization signal for a first cell from a base station via said one or more transceivers; and Based on receiving the on-demand synchronization signal from the base station within a specific unit time, first information related to the first beam failure is set to be transmitted to the base station through the one or more transceivers based on the on-demand synchronization signal, Based on not receiving the on-demand synchronization signal from the base station, second information related to a second beam failure based on a reference signal is transmitted by the terminal to the base station, The terminal wherein the specific unit time is based on the first setting information. A step of transmitting first configuration information related to an on-demand synchronization signal for the first cell by the base station to the terminal; and A step of receiving, by the base station, first information related to a first beam failure from the terminal based on the on-demand synchronization signal, based on the on-demand synchronization signal, based on the on-demand synchronization signal, Based on not receiving the on-demand synchronization signal from the base station, second information related to a second beam failure based on a reference signal is received from the terminal by the base station, A method wherein the specific unit time is based on the first setting information. In a base station, the base station: one or more transceivers; and comprising one or more processors coupled to said one or more transceivers; One or more of the above processors: Transmitting first configuration information related to an on-demand synchronization signal for the first cell to the terminal via the one or more transceivers; and Based on receiving the on-demand synchronization signal from the base station within a specific unit time, first information related to the first beam failure is set to be received from the terminal through the one or more transceivers based on the on-demand synchronization signal, Based on not receiving the on-demand synchronization signal from the base station, second information related to a second beam failure based on a reference signal is received from the terminal by the base station, The base station, wherein the specific unit time is based on the first setting information. In a processing device configured to control a terminal, the processing device: one or more processors; and One or more computer memories operatively connected to said one or more processors and storing instructions that perform operations based on execution by said one or more processors, The above actions are: An operation of receiving first configuration information related to an on-demand synchronization signal for a first cell from a base station; and An operation of transmitting first information related to a first beam failure to the base station based on the on-demand synchronization signal, based on the on-demand synchronization signal, based on the on-demand synchronization signal, Based on not receiving the on-demand synchronization signal from the base station, second information related to a second beam failure based on a reference signal is transmitted by the terminal to the base station, A processing device wherein the specific unit time is based on the first setting information. One or more non-transitory computer-readable media storing one or more instructions, The one or more instructions are executed by one or more processors so that the device: Receiving first configuration information related to an on-demand synchronization signal for the first cell from a base station; and Based on receiving the on-demand synchronization signal from the base station within a specific unit time, first information related to the first beam failure is controlled to be transmitted to the base station based on the on-demand synchronization signal, Based on not receiving the on-demand synchronization signal from the base station, second information related to a second beam failure based on a reference signal is transmitted by the terminal to the base station, A computer-readable medium wherein the specific unit time is based on the first setting information.

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