Method for performing LTM in wireless communication system, and device using method

Abstract

An operation method of a device in a wireless communication system, and a device using the method are provided. According to the method, a terminal receives an L1 / L2 triggered mobility (LTM) channel state information (CSI) resource configuration from a base station, performs measurement in one channel state information reference signal (CSI-RS) resource set on the basis of the LTM CSI resource configuration, transmits the measurement result to the base station, and receives a cell switch command from the base station through a medium access control control element (MAC CE), wherein the LTM CSI resource configuration is configured such that CSI-RS resources of different candidate cells are included in the one CSI-RS resource set.

Description

Method for performing LTM in a wireless communication system and device using the method

[0001] The present disclosure relates to a method for performing LTM (L1 / L2 Triggered Mobility) of a device in a wireless communication system and a device using the method.

[0002] As more and more communication devices demand greater communication capacity, the need for improved mobile broadband communications over existing radio access technology (RAT) is emerging. Furthermore, massive Machine Type Communications (MTC), which connects numerous devices and objects to provide diverse services anytime, anywhere, is also a key issue to be considered in next-generation communications. Furthermore, communication system design that considers reliability and latency-sensitive services / terminals is being discussed. The introduction of next-generation radio access technologies that take enhanced mobile broadband communications, massive MTC, and URLLC (Ultra-Reliable and Low Latency Communication) into account is being discussed. For convenience, these technologies are referred to herein as new RAT or NR.

[0003] Meanwhile, in wireless communication systems, mobility has been continuously developed for handover of terminals to base stations. For example, the conventional 3GPP (3 rd In the Generation Partnership Project (NR Release)-18, LTM (L1 / L2 triggered mobility) was introduced.

[0004] LTM aims to reduce interruption time and improve mobility robustness compared to conventional handover.

[0005] Conventional handovers are primarily based on Layer 3 (L3) measurement reports. The terminal measures the signal quality of neighboring cells and transmits an L3 report to the network (base station), which then makes a handover decision based on this report. However, this conventional handover method can have the following drawbacks.

[0006] 1) Long disconnect times: L3 signaling is time-consuming and may result in disconnect times during handover, which can be critical for delay-sensitive services such as extended reality or real-time communications.

[0007] 2) Possibility of Radio Link Failure: If the signal quality deteriorates rapidly, L3 reports may not be transmitted in time or the network's handover decision may be delayed, which may lead to radio link failure.

[0008] LTM is a method to perform handover faster by utilizing L1 (physical layer, layer 1) and L2 (MAC layer, layer 2) signals to compensate for the shortcomings of the existing L3-based handover.

[0009] However, in the LTM in Release 18, CSI (channel state information) reports were performed using only the SSB (synchronization signal / physical broadcast channel (SS / PBCH) block) using a broad beam. It is necessary to design more efficient LTM operations.

[0010] The technical problem to be solved by the present disclosure is to provide a method for performing LTM of a device in a wireless communication system and a device using the method.

[0011] A method for performing LTM by a terminal in a wireless communication system is provided. According to the method, the terminal receives LTM (L1 / L2 triggered mobility) CSI (Channel State Information) resource configuration from a base station, performs measurement in one CSI-RS (Channel State Information Reference Signal) resource set based on the LTM CSI resource configuration, transmits the result of the measurement to the base station, and receives a cell switch command from the base station through a MAC CE (Medium Access Control Control Element). In this process, the LTM CSI resource configuration is characterized in that the CSI-RS resources of different candidate cells are configured to be included in the one CSI-RS resource set.

[0012] In another aspect, a terminal, chipset and computer-readable medium for executing the above method are provided.

[0013] In another aspect, a method of operating a base station and a base station using the method are provided. According to the method, the base station transmits an LTM CSI resource configuration to a terminal, and receives, from the terminal, a measurement result for one CSI-RS resource set based on the LTM CSI resource configuration, and the base station transmits a cell switch command to the terminal through a MAC CE, wherein the LTM CSI resource configuration is characterized in that the CSI-RS resources of different candidate cells are configured to be included in the one CSI-RS resource set.

[0014] According to the method according to the present disclosure, when performing an LTM operation, the operation can be performed based on CSI-RS rather than based on SSB as in the past. Specifically, the terminal performs measurements in a single CSI-RS resource set based on the LTM CSI resource configuration, and the single CSI-RS resource set can include CSI-RS resources of different candidate cells. Since the CSI-RS resources of different candidate cells exist in the same resource set, the terminal can simply compare the CSI values ​​of different candidate cells without separate configuration.

[0015] In addition, according to this specification, when using CSI-RS for LTM operation, by clearly specifying which CSI-RS to measure and report, how many CSI-RSs to measure and how to report, etc., ambiguity does not occur during LTM operation between the base station and the terminal.

[0016] Figure 1 illustrates the system architecture of a New Generation Radio Access Network (NG-RAN) to which NR is applied.

[0017] Figure 2 is a block diagram showing a radio protocol architecture for a user plane.

[0018] Figure 3 is a block diagram showing the wireless protocol structure for the control plane.

[0019] Figure 4 illustrates the functional division between NG-RAN and 5GC.

[0020] Figure 5 illustrates a frame structure that can be applied in NR.

[0021] Figure 6 shows an example of a resource grid in NR.

[0022] Figure 7 shows an example of a physical resource block in NR.

[0023] Figure 8 illustrates the slot structure of an NR frame.

[0024] Figure 9 illustrates a core set.

[0025] Figure 10 illustrates an example of a slot structure for a new wireless access technology.

[0026] Figure 11 illustrates the structure of a self-contained slot.

[0027] Figure 12 illustrates physical channels and typical signal transmission.

[0028] Figure 13 illustrates the signaling process for LTM.

[0029] Figure 14 illustrates the operation method of the terminal.

[0030] Figure 15 illustrates the signaling process and operation between a base station and a terminal.

[0031] Figure 16 illustrates a wireless device applicable to the present specification.

[0032] Figure 17 illustrates another example of a wireless device.

[0033] Figure 18 illustrates an example of a signal processing module structure.

[0034] Figure 19 illustrates another example of the structure of a signal processing module within a transmission device.

[0035] FIG. 20 illustrates an example of a wireless communication device according to an implementation example of the present disclosure.

[0036] Fig. 21 illustrates a communication system (1) applied to this specification.

[0037] As used herein, "A or B" can mean "only A," "only B," or "both A and B." In other words, as used herein, "A or B" can be interpreted as "A and / or B." For example, as used herein, "A, B or C" can mean "only A," "only B," "only C," or "any combination of A, B and C."

[0038] As used herein, a slash ( / ) or a comma can mean "and / or." For example, "A / B" can mean "A and / or B." Accordingly, "A / B" can mean "only A," "only B," or "both A and B." For example, "A, B, C" can mean "A, B, or C."

[0039] In this specification, "at least one of A and B" may mean "only A", "only B" or "both A and B". Additionally, in this specification, the expressions "at least one of A or B" or "at least one of A and / or B" may be interpreted identically to "at least one of A and B".

[0040] Additionally, in this specification, “at least one of A, B and C” can mean “only A,” “only B,” “only C,” or “any combination of A, B and C.” Additionally, “at least one of A, B or C” or “at least one of A, B and / or C” can mean “at least one of A, B and C.”

[0041] Additionally, parentheses used herein may mean "for example." Specifically, when "control information (ABC)" is indicated, "ABC" may be described as an example of "control information." For example, "control information" may include DEF as another example. In other words, "control information" in this specification is not limited to "ABC," and "ABC" may be described as an example of "control information." Furthermore, even when indicated as "control information (i.e., ABC)," "ABC" may be described as an example of "control information."

[0042] Additionally, in this specification, terms such as “first,” “second,” etc. are used only for the purpose of distinguishing one component from another, and are not used to limit the components, and do not limit the order or importance between the components unless specifically limited. Accordingly, a first component in one embodiment of this specification 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.

[0043] In the following explanation, ‘when, if, in case of’ can be replaced with ‘based on’.

[0044] Technical features individually described within a single drawing in this specification may be implemented individually or simultaneously. The following drawings are designed to illustrate specific examples of this specification. The names of specific devices and the names of specific signals, messages, and fields depicted in the drawings are provided for illustrative purposes only, and therefore, the technical features of this specification are not limited to the specific names used in the drawings.

[0045] In this specification, a terminal is a user equipment (UE) or a consumer-side device, and may also be referred to as a base station / second node / IAB node / TRP (Transmission-Reception Point) that receives / transmits signals from / to. A terminal may correspond to a physical node or a logical node. A terminal may correspond to an endpoint on the user side, or may correspond to an intermediate point between other endpoints. In communication between two points that are not limited to endpoints (including one-to-one / many-to-one / one-to-many / many-to-many communication), a terminal may correspond to a served node. A terminal may be a node with a fixed location, or a node with an unfixed location (or mobile).

[0046] In this specification, a base station (BS) is a device on the network side, and may be referred to as a second node / IAB node / x-NodeB (x-NodeB, x may be an abbreviation related to radio access technology (RAT)) / TRP. A BS may correspond to a physical node or a logical node. A BS may correspond to an endpoint on the network side, or may correspond to an intermediate point between other endpoints. In communication between two points that are not limited to endpoints (including one-to-one / many-to-one / one-to-many / many-to-many communication), a BS may correspond to a serving node. A BS may be a node with a fixed location, or a node with an unfixed location.

[0047] In this specification, higher layer parameters may be set for the terminal, preset, or predefined. For example, the base station may transmit higher layer parameters to the terminal. For example, the terminal may transmit parameters such as capabilities to the base station as higher layer parameters. For example, the higher layer parameters may be transmitted via radio resource control (RRC) signaling or medium access control (MAC) signaling.

[0048] In this specification, the information / state / parameter being “configured or pre-configured” can be interpreted as the information / state / parameter being provided / pre-provided to the terminal through pre-defined signaling (e.g., SIB, MAC, RRC) from the base station. In this specification, the information / state / parameter being “defined or pre-defined” can be interpreted as the information / state / parameter being known in advance or pre-stored at the base station and the terminal without signaling between the base station and the terminal.

[0049] The technology described in this specification can be used in various wireless communication systems such as CDMA (code division multiple access), FDMA (frequency division multiple access), TDMA (time division multiple access), OFDMA (orthogonal frequency division multiple access), and SC-FDMA (single carrier frequency division multiple access). 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 (Institute of Electrical and Electronics Engineers) 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802-20, E-UTRA (evolved UTRA), LTE (long term evolution), and 5G NR.

[0050] The technology described in this specification can be implemented with 6G wireless technology and applied to various 6G systems. For example, the 6G system can have key factors such as enhanced mobile broadband (eMBB), ultra-reliable low latency communications (URLLC), massive machine-type communication (mMTC), artificial intelligence (AI) integrated communication, tactile internet, high throughput, high network capacity, high energy efficiency, low backhaul and access network congestion, and enhanced data security.

[0051] Hereinafter, downlink (DL) refers to communication from a base station to a terminal, and uplink (UL) refers to communication from a terminal to a base station. In downlink, a transmitter may be part of a base station, and a receiver may be part of a terminal. In uplink, a transmitter may be part of a terminal, and a receiver may be part of a base station. A base station may be expressed as a first communication device, and a terminal may be expressed as a second communication device. A base station (BS) may be replaced by terms such as a fixed station, Node B, eNB (evolved-NodeB), gNB (Next Generation NodeB), BTS (base transceiver system), access point (AP: Access Point), network (5G network), AI (Artificial Intelligence) system / module, RSU (road side unit), robot, drone (Unmanned Aerial Vehicle, UAV), AR (Augmented Reality) device, VR (Virtual Reality) device, etc.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, drone (Unmanned Aerial Vehicle, UAV), AR (Augmented Reality) device, VR (Virtual Reality) device, etc.

[0052] The following technologies can be used in various wireless access systems, such as CDMA, FDMA, TDMA, OFDMA, and SC-FDMA. UTRA is part of UMTS (Universal Mobile Telecommunications System). 3GPP (3rd Generation Partnership Project) LTE (Long Term Evolution) is 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.

[0053] For clarity, the description is based on the 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 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. For background technology, 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:

[0054] 3GPP LTE

[0055] - 36.211: Physical channels and modulation

[0056] - 36.212: Multiplexing and channel coding

[0057] - 36.213: Physical layer procedures

[0058] - 36.300: Overall description

[0059] - 36.331: Radio Resource Control (RRC)

[0060] 3GPP NR

[0061] - 38.211: Physical channels and modulation

[0062] - 38.212: Multiplexing and channel coding

[0063] - 38.213: Physical layer procedures for control

[0064] - 38.214: Physical layer procedures for data

[0065] - 38.300: NR and NG-RAN Overall Description

[0066] - 36.331: Radio Resource Control (RRC) protocol specification

[0067] As more and more communication devices demand greater communication capacity, the need for improved mobile broadband communication compared to existing radio access technologies is emerging. Furthermore, massive Machine Type Communications (MTC), which connects numerous devices and objects to provide various services anytime, anywhere, is also a key issue to be considered in next-generation communications. Furthermore, communication system design that considers reliability and latency-sensitive services / terminals is being discussed. Accordingly, the introduction of next-generation wireless access technologies such as enhanced mobile broadband communication (eMBB), massive MTC (MMTC), and Ultra-Reliable and Low Latency Communication (URLLC) is being discussed, and for convenience, these technologies are referred to as NR in this specification. NR is an expression representing an example of 5G radio access technology (RAT).

[0068] A new RAT system, including NR, uses OFDM transmission scheme or a similar transmission scheme. The new RAT system may follow OFDM parameters different from those of LTE. Alternatively, the new RAT system may follow the existing LTE / LTE-A numerology but have a larger system bandwidth (e.g., 100 MHz). Alternatively, a single cell may support multiple numerologies. For example, terminals operating under different numerologies may coexist within a single cell.

[0069] A numerology corresponds to a single subcarrier spacing in the frequency domain. Different numerologies can be defined by scaling the reference subcarrier spacing by an integer N.

[0070] The three key requirement areas for 5G include (1) Enhanced Mobile Broadband (eMBB), (2) Massive Machine Type Communication (mMTC), and (3) Ultra-reliable and Low Latency Communications (URLLC).

[0071] Some use cases may require optimization across multiple domains, while others may focus on just one Key Performance Indicator (KPI). 5G supports these diverse use cases in a flexible and reliable manner.

[0072] eMBB extends far beyond basic mobile internet access, encompassing rich interactive tasks, cloud computing, and augmented reality media and entertainment applications. Data is a key driver of 5G, and dedicated voice services may not be the first to emerge in the 5G era. In 5G, voice is expected to be handled as an application, simply using the data connection provided by the communication system. The primary drivers of increased traffic volume are the increasing size of content and the growing number of applications requiring high data rates. Streaming services (audio and video), interactive video, and mobile internet connectivity will become more prevalent as more devices connect to the internet. Many of these applications require always-on connectivity to push real-time information and notifications to users. Cloud storage and applications are rapidly growing on mobile communication platforms, applicable to both work and entertainment. Cloud storage is a particular use case driving the growth of uplink data rates. 5G is also used for remote work in the cloud, requiring significantly lower end-to-end latency to maintain a superior user experience when tactile interfaces are used. Entertainment, for example, cloud gaming and video streaming are other key factors driving the demand for mobile broadband. Entertainment is essential on smartphones and tablets, regardless of location, including in highly mobile environments such as trains, cars, and airplanes. Another use case is augmented reality and information retrieval for entertainment, where augmented reality requires extremely low latency and instantaneous data volumes.

[0073] Additionally, one of the most anticipated 5G use cases involves the ability to seamlessly connect embedded sensors across all sectors, such as mMTC. The number of potential IoT devices is projected to reach 20.4 billion by 2020. Industrial IoT is one area where 5G will play a key role, enabling smart cities, asset tracking, smart utilities, agriculture, and security infrastructure.

[0074] URLLC encompasses new services that will transform industries through ultra-reliable, low-latency links, such as remote control of critical infrastructure and self-driving vehicles. Reliability and latency are essential for smart grid control, industrial automation, robotics, and drone control and coordination.

[0075] Let's take a more specific look at several use cases.

[0076] 5G can complement fiber-to-the-home (FTTH) and cable-based broadband (or DOCSIS) by delivering streams rated at hundreds of megabits per second to gigabits per second. These high speeds are required to deliver TV at resolutions beyond 4K (6K, 8K, and beyond), as well as virtual and augmented reality. Virtual reality (VR) and augmented reality (AR) applications include near-immersive sports events. Certain applications may require specialized network configurations. For example, for VR games, game companies may need to integrate their core servers with the network operator's edge network servers to minimize latency.

[0077] Automotive is expected to be a significant new driver for 5G, with numerous use cases for in-vehicle mobile communications. Passenger entertainment, for example, demands simultaneous high-capacity and high-mobility mobile broadband. This is because future users will expect high-quality connectivity regardless of their location or speed. Another automotive application is an augmented reality dashboard, which overlays information on what the driver sees through the windshield, identifying objects in the dark and informing the driver about their distance and movement. In the future, wireless modules will enable communication between vehicles, the exchange of information between vehicles and supporting infrastructure, and between vehicles and other connected devices (e.g., devices accompanying pedestrians). Safety systems can guide drivers on alternative courses of action to ensure safer driving, reducing the risk of accidents. The next step will be remotely controlled or self-driving vehicles, which will require highly reliable and fast communication between different self-driving vehicles and between vehicles and infrastructure. In the future, self-driving cars will perform all driving tasks, leaving drivers to focus solely on traffic anomalies that the vehicles themselves cannot detect. The technological requirements for self-driving cars will require ultra-low latency and ultra-high-speed reliability, increasing traffic safety to levels unattainable by humans.

[0078] Smart cities and smart homes, often referred to as "smart societies," will be embedded with dense wireless sensor networks. A distributed network of intelligent sensors will identify conditions for cost- and energy-efficient maintenance of cities or homes. A similar setup can be implemented for each home. Temperature sensors, window and heating controllers, burglar alarms, and appliances will all be connected wirelessly. Many of these sensors typically have low data rates, low power, and low cost. However, for example, real-time HD video may be required for certain types of devices for surveillance purposes.

[0079] The consumption and distribution of energy, including heat and gas, are becoming increasingly decentralized, requiring automated control of distributed sensor networks. Smart grids interconnect these sensors using digital information and communication technologies to collect and act on information. This information can include the behavior of suppliers and consumers, enabling smart grids to improve efficiency, reliability, economic efficiency, sustainable production, and automated distribution of fuels like electricity. Smart grids can also be viewed as another low-latency sensor network.

[0080] The health sector has numerous applications that can benefit from mobile communications. Telecommunications systems can support telemedicine, which provides clinical care in remote locations. This can help reduce distance barriers and improve access to health services that are otherwise unavailable in remote rural areas. It can also be used to save lives in critical care and emergency situations. Mobile-based wireless sensor networks can provide remote monitoring and sensors for parameters such as heart rate and blood pressure.

[0081] Wireless and mobile communications are becoming increasingly important in industrial applications. Wiring is expensive to install and maintain. Therefore, the potential to replace cables with reconfigurable wireless links presents an attractive opportunity for many industries. However, achieving this requires wireless connections to operate with similar latency, reliability, and capacity to cables, while simplifying their management. Low latency and extremely low error rates are new requirements for 5G connectivity.

[0082] Logistics and freight tracking are important use cases for mobile communications, enabling the tracking of inventory and packages anywhere using location-based information systems. Logistics and freight tracking typically require low data rates but wide coverage and reliable location information.

[0083] Multi-Input Multi-Output (MIMO) technology in NR systems provides a scalable and flexible MIMO framework. Basically, it includes beam-based operation, scalable and flexible Channel State Information (CSI) codebook, reference signal (RS) design, and codebook design for CSI Type I and CSI Type II. Additionally, improvements have been introduced to support a CSI Type II codebook for multi-user (MU)-MIMO, multiple transmit / receive points (TRPs) or multiple panel transmission operations depending on backhaul conditions, multi-beam operation, high uplink transmit power support, and reference signals with low Peak-to-Average Power Ratio (PAPR) characteristics. Furthermore, beam management methods to reduce beam failure for wireless devices moving at high frequencies, expansion of multi-TRP transmission in uplink and downlink, sounding reference signals (SRSs) for capacity and coverage expansion, and improvements to Type II CSI-RSs can be supported.

[0084] Describes a conventional wireless communication system. This may also be called an Evolved-UMTS Terrestrial Radio Access Network (E-UTRAN) or a Long Term Evolution (LTE) / LTE-A system.

[0085] E-UTRAN includes a base station (BS), which provides a control plane and a user plane to user equipment (UE). A UE may be fixed or mobile, and may be referred to by other terms such as a mobile station (MS), a user terminal (UT), a subscriber station (SS), a mobile terminal (MT), a wireless device, or a terminal. A base station (BS) is a fixed point that communicates with a UE, and may be referred to by other terms such as an evolved-NodeB (eNB), a gNodeB (gNB), a base transceiver system (BTS), or an access point.

[0086] Base stations can be interconnected via the X2 interface. Base stations are connected to the Evolved Packet Core (EPC) via the S1 interface, more specifically, to the Mobility Management Entity (MME) via the S1-MME, and to the Serving Gateway (S-GW) via the S1-U.

[0087] The EPC consists of an MME, an S-GW, and a P-GW (Packet Data Network Gateway). The MME holds information about terminal access and capabilities, and this information is primarily used for terminal mobility management. The S-GW is a gateway that terminates on the E-UTRAN, and the P-GW is a gateway that terminates on the PDN.

[0088] Figure 1 illustrates the system architecture of a New Generation Radio Access Network (NG-RAN) to which NR is applied.

[0089] Referring to Fig. 1, the NG-RAN may include gNBs and / or eNBs that provide user plane and control plane protocol termination to the UE. Fig. 1 exemplifies a case including only gNBs. The gNBs (eNBs) are connected to each other via Xn interfaces. The gNBs and eNBs are connected to the 5th generation core network (5G Core Network: 5GC) via the NG interface. More specifically, they are connected to the access and mobility management function (AMF) via the NG-C interface, and to the user plane function (UPF) via the NG-U interface.

[0090] The layers of the radio interface protocol between the terminal and the network can be divided into L1 (layer 1), L2 (layer 2), and L3 (layer 3) based on the three lower layers of the Open System Interconnection (OSI) standard model, which is widely known in communication systems. Among these, the physical layer belonging to layer 1 provides information transfer service using physical channels, and the RRC (Radio Resource Control) layer located in layer 3 controls radio resources between the terminal and the network. To this end, the RRC layer exchanges RRC messages between the terminal and the base station.

[0091] Figure 2 is a block diagram illustrating the radio protocol architecture for the user plane. Figure 3 is a block diagram illustrating the radio protocol architecture for the control plane. The user plane is a protocol stack for transmitting user data, and the control plane is a protocol stack for transmitting control signals.

[0092] Referring to Figures 2 and 3, the physical layer (PHY layer) provides information transfer services to upper layers using physical channels. The PHY layer is connected to its upper layer, the Medium Access Control (MAC) layer, through a transport channel. Data is transferred between the MAC layer and the PHY layer via the transport channel. Transport channels are classified based on how and with what characteristics data is transmitted over the wireless interface.

[0093] Data travels between different physical layers, i.e., between the physical layers of a transmitter and receiver, via a physical channel. This physical channel can be modulated using Orthogonal Frequency Division Multiplexing (OFDM) and utilizes time and frequency as radio resources.

[0094] The MAC layer's functions include mapping between logical channels and transport channels, and multiplexing / demultiplexing MAC service data units (SDUs) belonging to logical channels into transport blocks provided as physical channels on the transport channels. The MAC layer provides services to the RLC (Radio Link Control) layer through logical channels.

[0095] The functions of the RLC layer include concatenation, segmentation, and reassembly of RLC SDUs. To guarantee the various Quality of Service (QoS) required by radio bearers (RBs), the RLC layer provides three operating modes: Transparent Mode (TM), Unacknowledged Mode (UM), and Acknowledged Mode (AM). AM RLC provides error correction through automatic repeat request (ARQ).

[0096] The RRC (Radio Resource Control) layer is defined only in the control plane. The RRC layer is responsible for controlling logical, transport, and physical channels, including the configuration, reconfiguration, and release of radio bearers. An RB is a logical path provided by Layer 1 (PHY layer) and Layer 2 (MAC layer, RLC layer, PDCP layer) for data transmission between a terminal and the network.

[0097] The functions of the Packet Data Convergence Protocol (PDCP) layer in the user plane include the transmission of user data, header compression, and ciphering. The functions of the Packet Data Convergence Protocol (PDCP) layer in the control plane include the transmission of control plane data and encryption / integrity protection.

[0098] Establishing an RB refers to the process of defining the characteristics of the radio protocol layer and channel to provide a specific service, and setting specific parameters and operating methods for each. RBs can be further divided into two types: signaling RBs (SRBs) and data RBs (DRBs). SRBs are used as a conduit for transmitting RRC messages in the control plane, while DRBs are used as conduits for transmitting user data in the user plane.

[0099] When an RRC connection is established between the RRC layer of the terminal and the RRC layer of the E-UTRAN, the terminal is in an RRC connected state, otherwise it is in an RRC idle state.

[0100] Downlink transmission channels that transmit data from the network to the terminal include the Broadcast Channel (BCH), which transmits system information, and the downlink Shared Channel (SCH), which transmits user traffic or control messages. Traffic or control messages for downlink multicast or broadcast services may be transmitted through the downlink SCH or a separate downlink Multicast Channel (MCH). Meanwhile, uplink transmission channels that transmit data from the terminal to the network include the Random Access Channel (RACH), which transmits initial control messages, and the uplink Shared Channel (SCH), which transmits user traffic or control messages.

[0101] Logical channels that are located above the transport channel and are mapped to the transport channel include BCCH (Broadcast Control Channel), PCCH (Paging Control Channel), CCCH (Common Control Channel), MCCH (Multicast Control Channel), and MTCH (Multicast Traffic Channel).

[0102] A physical channel consists of multiple OFDM symbols in the time domain and multiple subcarriers in the frequency domain. A single subframe consists of multiple OFDM symbols in the time domain. A resource block is a resource allocation unit and consists of multiple OFDM symbols and multiple subcarriers. Additionally, each subframe can use specific subcarriers of specific OFDM symbols (e.g., the first OFDM symbol) of the subframe for a Physical Downlink Control Channel (PDCCH), for example, an L1 / L2 control channel. A Transmission Time Interval (TTI) is a unit time for subframe transmission.

[0103] Figure 4 illustrates the functional division between NG-RAN and 5GC.

[0104] Referring to FIG. 4, the gNB can provide functions such as inter-cell radio resource management (Inter Cell RRM), radio bearer management (RB control), connection mobility control (Connection Mobility Control), radio admission control (Radio Admission Control), measurement configuration and provision, and dynamic resource allocation. The AMF can provide functions such as NAS security and idle state mobility processing. The UPF can provide functions such as mobility anchoring and PDU processing. The SMF (Session Management Function) can provide functions such as terminal IP address allocation and PDU session control.

[0105] Figure 5 illustrates a frame structure that can be applied in NR.

[0106] Referring to FIG. 5, a radio frame (hereinafter abbreviated as a frame) can be used for uplink and downlink transmission in NR. A frame has a length of 10 ms and can be defined as two 5 ms half-frames (Half-Frames, HF). A half-frame can be defined as five 1 ms sub-frames (Subframes, SF). A frame can include 10 sub-frames. A sub-frame can be divided into one or more slots, and the number of slots in a sub-frame depends on the Subcarrier Spacing (SCS). Each slot includes 12 or 14 OFDM (A) symbols depending on the cyclic prefix (CP). When a normal CP is used, each slot includes 14 symbols. When an extended CP is used, each slot includes 12 symbols. Here, the symbol may include an OFDM symbol (or CP-OFDM symbol), an SC-FDMA symbol (or a DFT-s-OFDM symbol). A mini-slot may include, for example, 2, 4, or 7 symbols, or may include more or fewer symbols.

[0107] NR systems can support multiple numerologies. Numerologies can be defined by subcarrier spacing and cyclic prefix (CP) overhead. Multiple subcarrier spacings can be derived by scaling the basic subcarrier spacing by an integer N. Furthermore, even if it is assumed that very low subcarrier spacing is not utilized at very high carrier frequencies, the numerologies utilized can be selected independently of the frequency band. Furthermore, NR systems can support various frame structures corresponding to multiple numerologies.

[0108] Below, we examine the Orthogonal Frequency Division Multiplexing (OFDM) numerologies and frame structures that can be considered in NR systems. Table 1 lists the various OFDM numerologies supported in NR systems.

[0109] Table 1 below illustrates the subcarrier spacing configuration μ (also referred to as subcarrier spacing configuration).

[0110] [Table 1]

[0111]

[0112] Regarding the frame structure in the NR system, the sizes of the various fields in the time domain are T s =1 / (Δf max ·N f ) can be expressed as a multiple of the time unit. Here, Δf max =480·10 3 and N f =409. Downlink and uplink transmissions are T f =(Δf max ·N f / 100)·T s = It consists of a radio frame with a duration of 10ms. Here, each radio frame is T sf =(Δf max ·N f / 1000)·T s = It consists of 10 subframes with a duration of 1ms. In this case, there may be one set of frames for uplink and one set of frames for downlink. In addition, the transmission of uplink frame number i from a terminal (User Equipment, UE) is T earlier than the start of the corresponding downlink frame from the terminal. TA =N TA ·T sIt must start before. For numerology μ, slots are n within a subframe. μ s ∈{0, ..., N slots,μ subframe -1} are numbered in increasing order, and n within a radio frame μ s,f ∈{0, ..., N slots,μ frame -1} are numbered in increasing order. One slot is N μ symb It consists of consecutive OFDM symbols, and N μ symb is determined by the numerology and slot configuration used. Slot n in a subframe μ s The start of OFDM symbol n in the same subframe μ s N μ symb are aligned temporally with the start of the OFDM signal. Not all terminals can transmit and receive simultaneously, which means that not all OFDM symbols in a downlink slot or uplink slot can be utilized.

[0113] Table 2 below shows the number of slots (N) in a frame according to the subcarrier spacing setting μ. frame,μ slot ), number of slots in a subframe (N subframe,μ slot ), number of symbols in the slot (N slot symb ) are examples.

[0114] [Table 2]

[0115]

[0116] Table 3 below illustrates that when extended CP is used, the number of symbols per slot, the number of slots per frame, and the number of slots per subframe change depending on the SCS.

[0117] [Table 3]

[0118]

[0119] In an NR system, OFDM(A) numerologies (e.g., SCS, CP length, etc.) may be set differently between multiple cells that are merged into a single terminal. Accordingly, the (absolute time) interval of a time resource (e.g., SF, slot, or TTI) (conveniently referred to as TU (Time Unit)) consisting of the same number of symbols may be set differently between the merged cells.

[0120] In relation to physical resources in an NR system, antenna ports, resource grids, resource elements, resource blocks, and carrier parts can be considered. Hereinafter, the physical resources that can be considered in an NR system will be described in detail. First, with respect to antenna ports, an antenna port is defined such that the channel through which a symbol on the antenna port is carried can be inferred from the channel through which another symbol on the same antenna port is carried. If the large-scale properties of the channel through which a symbol on one antenna port is carried can be inferred from the channel through which a symbol on another antenna port is carried, then 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 properties include one or more of delay spread, Doppler spread, frequency shift, average received power, and received timing.

[0121] Figure 6 shows an example of a resource grid in NR.

[0122] Referring to Figure 6, the resource grid is N in the frequency domain. μ RB N RB sc It consists of subcarriers, and one subframe is 14·2 μ It is described as an example, but not limited to, that it consists of OFDM symbols. In an NR system, the transmitted signal is N μ RB N RB sc One or more resource grids consisting of subcarriers and 2 μ N (μ) symb is described by OFDM symbols. Here, N μ RB≤ N max,μ RB is. The above N max,μ RB represents the maximum transmission bandwidth, which may vary between numerologies as well as between uplink and downlink. In this case, one resource grid may be configured for each numerology μ and each antenna port p. Each element of the resource grid for numerology μ and each antenna port p is referred to as a resource element and is uniquely identified by an index pair {index in the frequency domain, position of the symbol within the subframe}. If there is no risk of confusion or if a particular antenna port or numerology is not specified, the indices p and μ may be dropped. In addition, a resource block (RB) is defined as N in the frequency domain. RB sc =12 is defined as a series of consecutive subcarriers.

[0123] Point A serves as a common reference point of the resource block grid and is obtained as follows.

[0124] offsetToPointA for primary cell (Pcell) downlink represents the frequency offset between the lowest subcarrier of the lowest resource block overlapping the SS / PBCH block used by the terminal for initial cell selection and point A, expressed in resource block units assuming 15 kHz subcarrier spacing for FR1 and 60 kHz subcarrier spacing for FR2, and absoluteFrequencyPointA represents the frequency-location of point A expressed as in absolute radio-frequency channel number (ARFCN).

[0125] Common resource blocks (CRBs) are numbered from 0 upwards in the frequency domain for a subcarrier spacing setting μ. The center of subcarrier 0 of CRB 0 for a subcarrier spacing setting μ coincides with 'point A'. CRB number n in the frequency domain μ CRB The resource elements (k,l) for the subcarrier spacing setting μ are given by the following equation.

[0126] [Formula 1]

[0127]

[0128] k is defined relative to point A so that k=0 corresponds to the subcarrier centered at point A. Physical resource blocks are numbered from 0 to N within the bandwidth part (BWP). size BWP,i - Numbered from 1 to 1, where i is the number of BWP. Physical resource block n in BWP i PRB and common resource block n CRBThe relationship between them is given by the equation below.

[0129] [Formula 2]

[0130]

[0131] N start BWP,i is a common resource block where BWP starts relative to common resource block 0.

[0132] Figure 7 shows an example of a physical resource block in NR.

[0133] Referring to FIG. 7, a physical resource block (PRB) may be composed of different frequency resources and time resources depending on the subcarrier spacing.

[0134] Figure 8 illustrates the slot structure of an NR frame.

[0135] Referring to FIG. 8, a slot may include multiple symbols in the time domain. For example, in the case of a normal CP, one slot may include 14 symbols, but in the case of an extended CP, one slot may include 12 symbols. A carrier may include multiple subcarriers in the frequency domain. A Resource Block (RB) may be defined as multiple (e.g., 12) consecutive subcarriers in the frequency domain. A Bandwidth Part (BWP) may be defined as multiple consecutive (P)RBs in the frequency domain, and may correspond to one numerology (e.g., SCS, CP length, etc.). A carrier may include up to N BWPs (e.g., 4 or 5). Data communication is performed through activated BWPs, and only one BWP may be activated for one terminal. In the resource grid, each element is referred to as a Resource Element (RE), to which one complex symbol can be mapped.

[0136] As another example, in the time domain, a slot for a normal CP contains 7 symbols, but in the case of an extended CP, a slot contains 6 symbols. A carrier contains multiple subcarriers in the frequency domain. A Resource Block (RB) is defined as multiple (e.g., 12) consecutive subcarriers in the frequency domain. A Bandwidth Part (BWP) is defined as multiple consecutive (P)RBs in the frequency domain, and can correspond to a single numerology (e.g., SCS, CP length, etc.). A carrier can contain up to N (e.g., 5) BWPs. Data communication is performed through activated BWPs, and only one BWP can be activated for a single terminal. Each element in the resource grid is referred to as a Resource Element (RE), to which one complex symbol can be mapped.

[0137] A PDCCH (physical downlink control channel) may be composed of one or more CCEs (control channel elements) as shown in Table 4 below.

[0138] [Table 4]

[0139]

[0140] For example, a PDCCH can be transmitted via a resource consisting of 1, 2, 4, 8, or 16 CCEs, where a CCE is composed of 6 resource element groups (REGs), and one REG is composed of one resource block in the frequency domain and one orthogonal frequency division multiplexing (OFDM) symbol in the time domain.

[0141] Monitoring refers to decoding each PDCCH candidate according to the DCI (downlink control information) format. The terminal monitors a set of PDCCH candidates in one or more core sets (CORESETs, described below) on the active DL BWP of each activated serving cell for which PDCCH monitoring is configured, according to the corresponding search space set.

[0142] In NR, a new unit called a control resource set (CORESET) can be introduced. A terminal can receive PDCCHs in a CORESET.

[0143] Figure 9 illustrates a core set.

[0144] Referring to Figure 9, the core set is N in the frequency domain. CORESET RB It consists of N resource blocks and is in the time domain. CORESET symb ∈ {1, 2, 3} symbols. N CORESET RB , N CORESET symb can be provided by the base station via upper layer signals. As illustrated in Fig. 9, a core set may include multiple CCEs (or REGs).

[0145] A terminal may attempt PDCCH detection in units of 1, 2, 4, 8, or 16 CCEs within a core set. One or more CCEs for which PDCCH detection can be attempted may be referred to as PDCCH candidates.

[0146] A terminal can be configured with multiple core sets.

[0147] In conventional wireless communication systems (e.g., LTE / LTE-A), the control domain spans the entire system bandwidth used by the base station. Except for some terminals that support only narrow bandwidths (e.g., eMTC / NB-IoT terminals), all terminals must be able to receive radio signals across the entire system bandwidth of the base station to properly receive / decode the control information transmitted by the base station.

[0148] In contrast, NR introduces the aforementioned core set. A core set is a radio resource for control information that a terminal must receive. It can utilize only a portion of the system bandwidth in the frequency domain, rather than the entire bandwidth. Furthermore, it can utilize only a portion of the symbols within a slot in the time domain. The base station can assign a core set to each terminal and transmit control information through the assigned core set. In NR, a terminal can receive control information from the base station without necessarily receiving the entire system bandwidth.

[0149] The core set may include a terminal-specific core set for transmitting terminal-specific control information and a common core set for transmitting control information common to all terminals.

[0150] Meanwhile, in NR, depending on the application field, high reliability may be required, and in such a situation, the target block error rate (BLER) for downlink control information (DCI) transmitted through a downlink control channel (e.g., physical downlink control channel: PDCCH) may be significantly lower than in the prior art. One example of a method for satisfying such a requirement requiring high reliability is to reduce the amount of content included in the DCI and / or increase the amount of resources used when transmitting the DCI. In this case, the resources may include at least one of time domain resources, frequency domain resources, code domain resources, and spatial domain resources.

[0151] The following technologies / features can be applied in NR:

[0152] Self-contained subframe structure

[0153] Figure 10 illustrates an example of a slot structure for a new wireless access technology.

[0154] In NR, a structure in which a control channel and a data channel are time-division multiplexed (TDM) within one TTI, as shown in Fig. 10, can be considered for the purpose of minimizing latency.

[0155] FIG. 10 illustrates an example in which a downlink control region is located at the front of the TTI and an uplink control region is located at the back of the TTI. The region between the downlink control region and the uplink control region can be used for downlink data (DL data) transmission or uplink data (UL data) transmission. A characteristic of this structure is that downlink (DL) reception and uplink (UL) transmission are sequentially performed within a single subframe / slot, so that DL data can be received and UL ACK / NACK (Acknowledgement / Not-acknowledgement) can be transmitted within a single subframe / slot. As a result, the time required for data retransmission when a data transmission error occurs is reduced, thereby minimizing the latency of the final data transmission.

[0156] In this way, in a structure where data and control domains are TDMed, a time gap is required for the base station and terminal to transition from transmission mode to reception mode, or from reception mode to transmission mode. To this end, some OFDM symbols at the transition point from DL to UL in a self-contained subframe structure can be designated as a guard period (GP).

[0157] Figure 11 illustrates the structure of a self-contained slot.

[0158] In an NR system, a single slot may contain a DL control channel, DL or UL data, and a UL control channel. For example, the first N symbols in a slot may be used to transmit a DL control channel (hereinafter, referred to as a DL control region), and the last M symbols in the slot may be used to transmit a UL control channel (hereinafter, referred to as a UL control region). N and M are each integers greater than or equal to 0. A resource region (hereinafter, referred to as a data region) between the DL control region and the UL control region may be used for DL ​​data transmission or UL data transmission. As an example, the following configuration may be considered. Each section is listed in chronological order.

[0159] 1. DL only configuration

[0160] 2. UL only configuration

[0161] 3. Mixed UL-DL configuration

[0162] - DL area + GP (Guard Period) + UL control area

[0163] - DL control area + GP + UL area

[0164] DL area: (i) DL data area, (ii) DL control area + DL data area

[0165] UL domain: (i) UL data domain, (ii) UL data domain + UL control domain

[0166] In the DL control region, a PDCCH can be transmitted, and in the DL data region, a PDSCH (physical downlink shared channel) can be transmitted. In the UL control region, a PUCCH (physical uplink control channel) can be transmitted, and in the UL data region, a PUSCH (physical uplink shared channel) can be transmitted. In the PDCCH, downlink control information (DCI), such as DL data scheduling information and UL data scheduling information, can be transmitted. In the PUCCH, uplink control information (UCI), such as ACK / NACK (Positive Acknowledgement / Negative Acknowledgement) information for DL ​​data, CSI (Channel State Information) information, and SR (Scheduling Request), can be transmitted. GP provides a time gap when a base station and a terminal switch from transmission mode to reception mode or from reception mode to transmission mode. Some symbols at the time of switching from DL to UL within a subframe can be set as GP.

[0167] System information of an NR system can be transmitted in a broadcasting manner. At this time, analog beams belonging to different antenna panels within one symbol can be transmitted simultaneously, and a method of introducing a beam reference signal (BRS), which is a reference signal (RS) transmitted by applying a single analog beam (corresponding to a specific antenna panel) to measure a channel for each analog beam, is being discussed. The BRS can be defined for multiple antenna ports, and each antenna port of the BRS can correspond to a single analog beam. At this time, unlike the BRS, a synchronization signal or xPBCH can be transmitted by applying all analog beams within an analog beam group so that any terminal can receive it well.

[0168] In NR, a synchronization signal block (SSB, or may be referred to as a synchronization signal and physical broadcast channel (SS / PBCH) in the time domain) may be composed of four OFDM symbols numbered in ascending order from 0 to 3 within the synchronization signal block, and a primary synchronization signal (PSS), a secondary synchronization signal (SSS), and a PBCH associated with a demodulation reference signal (DMRS) may be mapped to the symbols. As described above, the synchronization signal block may also be referred to as an SS / PBCH block.

[0169] In NR, multiple synchronization signal blocks can be transmitted at different times, and SSB can be used to perform initial access (IA), serving cell measurement, etc. Therefore, when the transmission time and resources overlap with other signals, it is desirable to transmit SSB preferentially. To achieve this, the network can broadcast SSB transmission time and resource information or indicate it through UE-specific RRC signaling.

[0170] NR can perform beam-based transmission and reception operations. If the reception performance of the current serving beam degrades, a process called beam failure recovery (BFR) can be used to find a new beam.

[0171] Since BFR is not a process for declaring an error / failure in the link between the network and the terminal, it can be assumed that the connection with the current serving cell is maintained even when the BFR process is performed. During the BFR process, measurements are performed on different beams set by the network (a beam can be expressed as a CSI-RS port or an SSB (synchronization signal block) index, etc.) and the best beam for the terminal is selected. The terminal can proceed with the BFR process by performing the RACH process associated with the beam with the best measurement result.

[0172] Now, we will describe the Transmission Configuration Indicator (TCI) state. The TCI state can be set for each core set of the control channel, and parameters for determining the terminal's receive (Rx) beam can be determined based on the TCI state.

[0173] For each downlink bandwidth portion (DL BWP) of a serving cell, a terminal may be configured with up to three core sets. Additionally, for each core set, the terminal may be provided with the following information:

[0174] 1) Coreset index p (e.g., one from 0 to 11, where the index of each coreset can be uniquely determined among the BWPs of a serving cell),

[0175] 2) PDCCH DM-RS scrambling sequence initialization value,

[0176] 3) Interval in the time domain of the core set (can be given in symbol units),

[0177] 4) A set of resource blocks,

[0178] 5) CCE-to-REG mapping parameters,

[0179] 6) Antenna port quasi co-location (QCL) information indicating quasi co-location (QCL) information of DM-RS antenna ports for PDCCH reception in each core set (from a set of antenna port quasi co-locations provided by a higher layer parameter called 'TCI-State');

[0180] 7) Indicating the presence or absence of a transmission configuration indication (TCI) field for a specific DCI format transmitted by PDCCH in the core set, etc.

[0181] Let's explain QCL. If the characteristics of the channel through which a symbol on one antenna port is transmitted can be inferred from the characteristics of the channel through which a symbol on another antenna port is transmitted, then the two antenna ports are said to be in quasi-co-location (QCL). For example, if two signals (A and B) are transmitted from the same transmit antenna array with identical / similar spatial filters applied, the two signals may experience identical / similar channel conditions. From the receiver's perspective, if one of the two signals is received, the channel characteristics of the received signal can be used to detect the other signal.

[0182] In this sense, the fact that A and B are QCL may mean that A and B experienced similar channel conditions, and thus, the channel information estimated to detect A is also useful for detecting B. Here, the channel conditions may be defined by, for example, Doppler shift, Doppler spread, average delay, delay spread, spatial reception parameters, etc.

[0183] The 'TCI-State' parameter associates one or two downlink reference signals with a corresponding QCL type (there are QCL types A, B, C, and D, see Table 5).

[0184] [Table 5]

[0185]

[0186] Each 'TCI-State' may include parameters for establishing a quasi-colocation (QCL) relationship between one or two downlink reference signals and a DM-RS port of a PDSCH (or PDCCH), or a CSI-RS port of a CSI-RS resource.

[0187] Meanwhile, in each DL BWP configured for a terminal in a serving cell, the terminal may be provided with up to 10 search space sets. For each search space set, the terminal may be provided with at least one of the following pieces of information:

[0188] 1) Search space set index s (0≤s<40), 2) Association between core set P and search space set s, 3) PDCCH monitoring period and PDCCH monitoring offset (slot unit), 4) PDCCH monitoring pattern within a slot (e.g., indicating the first symbol of the core set within a slot for PDCCH monitoring), 5) Number of slots in which search space set s exists, 6) Number of PDCCH candidates per CCE aggregation level, 7) Information indicating whether search space set s is CSS (common search space) or USS (UE-specific search space), etc.

[0189] In NR, core set #0 can be configured by PBCH (or terminal-specific signaling for handover, PSCell configuration, or BWP configuration). The search space (SS) set #0 configured by PBCH can have different monitoring offsets (e.g., slot offset, symbol offset) for each associated SSB. This may be necessary to minimize the search space occasions that the terminal must monitor. Alternatively, it may also be necessary to provide a beam sweeping control / data area that can transmit control / data for each beam so that communication with the terminal can be continuously performed in a situation where the best beam of the terminal dynamically changes.

[0190] Figure 12 illustrates physical channels and typical signal transmission.

[0191] Referring to Figure 12, in a wireless communication system, a terminal receives information from a base station via the downlink (DL), and the terminal transmits information to the base station via the uplink (UL). The information transmitted and received between the base station and the terminal includes data and various control information, and various physical channels exist depending on the type and purpose of the information they transmit and receive.

[0192] When a terminal is powered on again from a powered-off state or newly enters a cell, it performs an initial cell search operation, such as synchronizing with the base station (S11). To this end, the terminal receives the PSCH (Primary Synchronization Channel) and SSCH (Secondary Synchronization Channel) from the base station to synchronize with the base station and obtain information such as the cell ID (cell identity). In addition, the terminal can obtain broadcast information within the cell by receiving the PBCH (Physical Broadcast Channel) from the base station. In addition, the terminal can receive the DL RS (Downlink Reference Signal) during the initial cell search phase to check the downlink channel status.

[0193] (Initial) cell search can be defined as a procedure in which a terminal acquires time and frequency synchronization with a cell and detects the cell ID of the cell. Cell search can be based on the primary synchronization signal and secondary synchronization signal of the cell, and the PBCH DMRS.

[0194] A terminal that has completed initial cell search can obtain more specific system information by receiving a PDCCH (Physical Downlink Control Channel) and a corresponding PDSCH (Physical Downlink Control Channel) (S12).

[0195] Thereafter, the terminal can perform a random access procedure (Random Access Procedure) to complete connection to the base station (S13-S16). Specifically, the terminal can transmit a preamble through a Physical Random Access Channel (PRACH) (S13) and receive a Random Access Response (RAR) for the preamble through a PDCCH and a corresponding PDSCH (S14). Thereafter, the terminal can transmit a Physical Uplink Shared Channel (PUSCH) using scheduling information in the RAR (S15) and perform a contention resolution procedure (Contention Resolution Procedure) such as a PDCCH and a corresponding PDSCH (which can be considered a process of receiving a contention resolution message) (S16).

[0196] When accessing a base station for the first time or when there is no radio resource for signal transmission, a terminal may perform a random access procedure (RACH) for the base station. At this time, a 4-step contention-based or type-1 random access may include a first step in which the terminal transmits a random access preamble (or Msg1) to the base station, a second step in which the terminal receives a random access response (RAR) (or Msg2) from the base station, a third step in which the terminal transmits an uplink message (or Msg3) to the base station, and a fourth step in which the terminal receives a contention resolution message (or Msg4) from the base station. Alternatively, a 2-step contention-based or type-2 random access may include a step A in which the terminal transmits a random access preamble and an uplink message to the base station, and a step B in which the terminal receives a random access response and a contention resolution message from the base station. A contention-free random access procedure may only include steps 1 and 2 of a contention-based access procedure, and steps 3 and 4 are not required because no contention occurs between terminals.

[0197] The terminal can transmit a random access preamble or PRACH to the base station based on the random access opportunity (RO), preamble transmission power, etc. provided through SIB1 or dedicated RRC signaling. Here, the terminal can select an optimal SSB or CSI-RS (Channel Status Information-Reference Signal) and determine an RO and / or preamble index group associated with the selected SSB or CSI-RS. The terminal can select an optimal SSB and a corresponding reception beam from among a plurality of SSBs corresponding to the multi-beam sweeping of the base station during the initial access process. Meanwhile, after the initial access, the terminal can perform transmission beam and / or reception beam selection or change through a CSI measurement and reporting process based on the CSI-RS from the base station in an RRC connection state.

[0198] After the terminal transmits the preamble, the terminal can monitor RAR reception for a predetermined period of time. For example, the terminal can monitor the PDCCH scrambled with RA-RNTI and receive the RAR through the PDSCH transmitted in the resource scheduled by the DCI in the PDCCH. The RAR may include a Random Access Preamble Identifier (RAPID), an uplink grant (UL Grant) for Msg3 scheduling, a temporary cell identifier (Temporary C(Cell)-RNTI), and a Timing Advance Command (TAC) determined based on the preamble reception timing.

[0199] If the terminal fails to successfully receive the RAR, the preamble can be retransmitted by applying power ramping, etc.

[0200] If the terminal successfully receives the RAR, it can transmit Msg3 based on the UL grant within the RAR. Once Msg3 is transmitted, the terminal can start the contention resolution timer (CR timer) and perform PDCCH monitoring based on the C-RNTI for Msg4 reception. If Msg4 is received while the CR timer is running, the terminal can determine that contention resolution has been successfully completed.

[0201] A terminal that has performed the above-described procedure can then perform PDCCH / PDSCH reception (S17) and PUSCH / PUCCH (Physical Uplink Control Channel) transmission (S18) as general uplink / downlink signal transmission procedures. Control information that the terminal transmits to the base station is referred to as UCI (Uplink Control Information). UCI includes HARQ ACK / NACK (Hybrid Automatic Repeat and reQuest Acknowledgement / Negative-ACK), SR (Scheduling Request), CSI (Channel State Information), etc. CSI includes CQI (Channel Quality Indicator), PMI (Precoding Matrix Indicator), RI (Rank Indication), etc. UCI is generally transmitted through PUCCH, but can be transmitted through PUSCH when control information and data must be transmitted simultaneously. In addition, the terminal can aperiodically transmit UCI through PUSCH according to a request / instruction of the network. UCI can be repeatedly transmitted over PUCCH.

[0202] Meanwhile, the control information that the terminal transmits to the base station via the uplink (or that the terminal receives from the base station) may include downlink / uplink ACK / NACK signals, CQI (Channel Quality Indicator), PMI (Precoding Matrix Index), RI (Rank Indicator), etc. For example, in the case of a 3GPP LTE system, the terminal may transmit the above-described control information such as CQI / PMI / RI via PUSCH and / or PUCCH.

[0203] The table below shows an example of the DCI format.

[0204] [Table 6]

[0205]

[0206] Referring to Table 6 above, 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, NDI, RV, etc.), HARQ related information (e.g., process number, DAI, PDSCH-HARQ feedback timing, etc.), multi-antenna related information (e.g., DMRS sequence initialization information, antenna port, CSI request, etc.), power control information (e.g., PUSCH power control, etc.), and the control information included in each DCI format may be predefined.

[0207] DCI format 0_0 is used for scheduling PUSCH in a single cell. The information contained in DCI format 0_0 is CRC-scrambled and transmitted using C-RNTI, CS-RNTI, or MCS-C-RNTI.

[0208] DCI format 0_1 ​​is used to schedule one or more PUSCHs in a single cell, or to indicate configured grant (CG) downlink feedback information to the UE. The information contained in DCI format 0_1 ​​is CRC-scrambled and transmitted using the C-RNTI, CS-RNTI, SP-CSI-RNTI, or MCS-C-RNTI.

[0209] DCI format 0_2 is used for scheduling PUSCH in a single cell. The information contained in DCI format 0_2 is CRC-scrambled and transmitted using C-RNTI, CS-RNTI, SP-CSI-RNTI, or MCS-C-RNTI.

[0210] 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, VRB-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, TCI, 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.

[0211] DCI format 1_0 is used for scheduling PDSCH in a DL cell. The information contained in DCI format 1_0 is CRC-scrambled and transmitted using C-RNTI, CS-RNTI, or MCS-C-RNTI.

[0212] DCI format 1_1 is used for scheduling PDSCH in a single cell. Information included in DCI format 1_1 is CRC-scrambled and transmitted using C-RNTI, CS-RNTI, or MCS-C-RNTI.

[0213] DCI format 1_2 is used for scheduling PDSCH in a single cell. The information contained in DCI format 1_2 is CRC-scrambled and transmitted using C-RNTI, CS-RNTI, or MCS-C-RNTI.

[0214] Now, let's talk about LTM (L1 / L2 Triggered Mobility).

[0215] LTM is a procedure in which the gNB receives an L1 measurement report from the UE and, based on this, changes the UE's serving cell through a cell switch command signaled via MAC CE. The cell switch command indicates an LTM candidate configuration prepared in advance by the gNB and provided to the UE via RRC signaling. The UE then switches to the target configuration according to the cell switch command. The LTM procedure can be used to reduce mobility latency.

[0216] If configured by the network, the TCI states of one or more cells other than the current serving cell can be activated. For example, the TCI state of an LTM candidate cell can be activated before that cell becomes the serving cell. This allows the UE to perform downlink synchronization with that cell and, when a cell switch is triggered, to switch to one of the cells more quickly. All activated TCI states, except those received in the cell switch command, are deactivated when the LTM cell switch is executed.

[0217] In this way, in wireless communication systems, mobility has been continuously developed for handover of terminals to base stations. For example, the conventional 3GPP (3 rdIn the NR Release-18 of the NR Generation Partnership Project, handover for low latency was designed through LTM. However, in the LTM of Release 18, CSI (channel state information) reports were performed using only SSB (synchronization signal / physical broadcast channel (SS / PBCH) block).

[0218] In contrast, the LTM performing method according to the present disclosure can utilize a channel state information-reference signal (CSI-RS) for more accurate beam reporting. Furthermore, future standards (e.g., 3GPP NR Release 19) may allow for LTM design using CSI-RS.

[0219] The most significant difference between SSB and CSI-RS is that CSI-RS uses sharper beams than SSB. While CSI-RS offers the advantage of sharper beams, enabling more accurate beamforming for terminals, the downside is a lower overall cell quality and cell access reliability.

[0220] Accordingly, even if a good beam quality is reported based on CSI-RS, the cell quality may be poor. In this case, when the terminal changes the beam for some reason, it may frequently move to another cell due to poor cell quality, which may result in a ping-pong phenomenon. In LTM operation, not only beam quality but also reliable cell quality values ​​are important factors. Since conventional LTM uses SSB, the conventional LTM method cannot be directly applied to LTM using CSI-RS.

[0221] Considering these points, the present disclosure describes how to set up measurement resources for CSI reporting (let's call them LTM CSI resources) in LTM operation. In addition, it describes which CRIs for each candidate cell / beam will be reported, how many to include in the report, and in what manner to report the CRIs, which are information included in the CSI-RS report in LTM operation, for each candidate cell / beam. For example, the terminal can determine the CSI-RS resource with the best channel status or exceeding a threshold among multiple CSI-RS resources transmitted by the base station and report the index of the corresponding CSI-RS resource. In this case, the index of the CSI-RS resource can be referred to as CRI.

[0222] Looking at the CSI-RS-ResourceConfigMobility and LTM-CSI-ResourceConfig IEs in existing standard specifications documents (e.g., 3GPP NR 38.331), we can see how the resource sets are configured for RRM and LTM, respectively. Table 7 shows an example of the CSI-RS-ResourceConfigMobility IE (information element). The CSI-RS-ResourceConfigMobility IE is used to configure CSI-RS-based RRM measurements.

[0223] [Table 7]

[0224]

[0225]

[0226] In Table 7, csi-rs-ResourceList-Mobility is a list of CSI-RS resources for mobility. csi-RS-CellList-Mobility is a list of cells for CSI-RS-based RRM measurement. refServCellIndex indicates a serving cell that provides a timing reference for CSI-RS resources without associated SSB. associatedSSB, if this field exists, allows the UE to base the timing of the CSI-RS resources indicated in CSI-RS-Resource-Mobility on the timing of the cell indicated by the cellId in CSI-RS-CellMobility. csi-RS-Index is a CSI-RS resource index associated with the CSI-RS resource to be measured (and used for reporting). firstOFDMSymbolInTimeDomain is a time domain allocation within a physical resource block. This field indicates the first OFDM symbol of the PRB used for CSI-RS. frequencyDomainAllocation is a frequency domain allocation within a physical resource block.

[0227] Table 8 is an example of an LTM-CSI-ResourceConfig IE. The LTM-CSI-ResourceConfig IE defines one or more CSI resource groups for one or more LTM candidate configurations.

[0228] [Table 8]

[0229]

[0230] In Table 8, ltm-CandidateIdList indicates the LTM candidate cell IDs associated with the SSBs in ltm-CSI-SSB-ResourceList. This list can have the same number of entries as ltm-CSI-SSB-ResourceList. The first entry in this list is linked to the first entry in ltm-CSI-SSB-ResourceList, the second entry is linked to the second entry in ltm-CSI-SSB-ResourceList, and so on.

[0231] ltm-CSI-SSB-ResourceList is used to indicate SS / PBCH block resources of one or more LTM candidate cells.

[0232] The contents of Tables 7 and 8 are summarized below.

[0233] 1) RRM: One candidate cell ID is set for each CSI-RS-CellMobility of IE CSI-RS-ResourceConfigMobility, and multiple CSI-RS-Resource-Mobility are set. In addition, the associated SSB is set within the CSI-RS-Resource-Mobility.

[0234] 2) LTM: The resource set configured in CMR is configured regardless of the candidate cell ID. That is, the SSBs of multiple candidate cells are configured in one resource set.

[0235] Table 9 is an example of a CSI-ReportConfig IE. The CSI-ReportConfig IE is used to configure periodic or semi-permanent reports transmitted on the PUCCH of the cell containing the CSI-ReportConfig, or to configure semi-permanent or aperiodic reports transmitted on the PUSCH triggered by DCI received from the cell containing the CSI-ReportConfig.

[0236] [Table 9]

[0237]

[0238]

[0239]

[0240]

[0241]

[0242]

[0243] In Table 9, csi-ReportingBand represents a subset of contiguous or non-contiguous subbands in the bandwidth portion for which CSI should be reported. csi-ReportSubConfigToAddModList is a list of CSI-ReportSubConfigurations to add or modify in the CSI report configuration. nrofReportedGroups is the number of resource groups reported per CSI report. nrofReportedRS is the number of measured RS resources reported per report configuration in non-group-based reports. resourcesForChannelMeasurement represents resources for channel measurements.

[0244] Table 10 is an example of the LTM-CSI-ReportConfig IE. The LTM-CSI-ReportConfig IE is used to configure reports for cells containing LTM-CSI-ReportConfig.

[0245] [Table 10]

[0246]

[0247]

[0248] In Table 10, ltm-ReportContent defines the content of the LTM L1 measurement report. reportSlotConfig indicates the periodicity and slot offset, and nrOfReportedCells defines the number of cells reported within a single L1 measurement report instance. nrOfReportedRS-PerCell defines the number of RSs per cell reported within a single L1 measurement report instance. spCellInclusion indicates whether the UE includes L1 measurement reports related to the current SpCell. This field can be set only when the current SpCell is configured as an LTM candidate cell.

[0249] Meanwhile, existing SSB-based LTM reports all CRIs simultaneously based on beams without differentiating between candidate cells when reporting SSBRI (Synchronization Signal Block Resource Indicator). However, when performing CSI-RS-based LTM, since CSI-RS uses sharper beams and has more beam types than SSB, it is possible to consider adding an additional step of cell selection for mobility. This can be defined when configuring resource sets, and CSI reports can include multiple resource sets in a single report. The factors to consider and each method are described below.

[0250] I. Scenario 1. When the resource set is set in cell units.

[0251] In conventional standards, only one resource set is defined per report. However, in CSI-RS, resource sets are set for each candidate cell to first assess quality at the cell level, and multiple resource sets can be transmitted in a single report.

[0252] In other words, a CSI-RS-based report configuration for LTM can configure N resource sets in a single report instance, and the terminal can independently report each resource set by at least one of the methods described below when the base station triggers the corresponding report configuration, or can configure specific M resource sets (M <N 또는 M=N)들에 대해서 하나의 리포트로 전송할 수도 있다.

[0253] As an advantage of this method, when the resource set is set in candidate cell units, CSI-RS resource information in the same cell is set in resource set units, so that the terminal can easily classify information by cell without setting up a separate base station.

[0254] For example, when a terminal wants to collect information about multiple SSBs or CSI-RSs due to cell quality measurement, etc., it can obtain the information it wants to collect by checking one resource set or a smaller number of resource sets.

[0255] As another example, when a terminal wants to report on a certain cell, it will be easier to include the resource set in the report when the resource information corresponding to the cell is gathered in one resource set or a smaller number of resource sets, rather than when the information for the cell is scattered across multiple resource sets.

[0256] First, since the aforementioned resources are for LTM, they will be configured by the LTM-CSI-ResourceConfig IE. While the existing LTM-CSI-ResourceConfig defines a resource set only for SSB, the LTM-CSI-ResourceConfig according to the present disclosure may include a definition for CSI-RS.

[0257] For example, CSI-RS resource set information for LTM can be entered in ltm-CSI-RS-ResourceSet-r19 in Table 11 below. Since this scenario assumes that resource sets are configured on a cell-by-cell basis, the CSI-RS resource set requires each candidate cell ID and a list of resources to be included in the resource set. For example, the information can be entered in each cell ID and ltm-CSI-RS-ResourceList-19.

[0258] Table 11 illustrates an LTM-CSI-ResourceConfig IE (information element) according to the present disclosure.

[0259] [Table 11]

[0260]

[0261] After measuring each CSI-RS resource, the terminal can perform an LTM report including the measured value and CRI of each resource.

[0262] Proposal 1. The UE (terminal) can prioritize cell quality when selecting a CRI and then report the CRIs within the cell.

[0263] In this scenario, since candidate cells are identified for each resource set, beam selection can be performed in a two-step process, following cell quality-based selection, for CRI selection. This has the advantage of enabling the selection of reliable, high-quality beams with low complexity through refined sequences, in preparation for situations where CSI-RS has a larger number of beams compared to SSB.

[0264] Table 12 illustrates RSRP measured on a single resource set.

[0265] [Table 12]

[0266]

[0267] In a case like Table 12, when reporting the top 4 resources according to RSRP order, the reported resource IDs are 0, 2, 3, and 4, and the resources of candidate cells 0, 1, and 2 will be selected. However, the other resource of candidate cell ID 0 has an RSRP order of 6, and the two resources of candidate cell ID 0 show a large difference in RSRP, so it can be said that in terms of cell quality, they have poorer quality than other candidate cells.

[0268] Therefore, to exclude candidate cell ID 0 from the reported resource, i) the quality of the candidate cell can be determined first, and then ii) the reported resource can be selected. If the resource of RSRP order 1 is excluded, the reported resource IDs are 2, 3, 4, and 5, which means that the resources of candidate cells 1 and 2 will be selected.

[0269] First, the following method can be applied to cell quality ordering for each resource set (candidate cell).

[0270] 1) Method of using CSI-RS to measure cell quality.

[0271] 2) Method of using SSB to measure cell quality.

[0272] These two methods each have their own advantages. Using CSI-RS eliminates the need for associated SSB, allowing terminals to assess cell quality solely through CSI-RS quality measurements. Using SSB offers the advantage of reliably measuring overall cell quality through a wider beam compared to CSI-RS. Each method is described in detail below.

[0273] <CSI-RS를 셀 품질 측정에 이용하는 방법>

[0274] This paper describes how to use CSI-RS to measure cell quality. Because CSI-RS is a sharp beam, a single value is not sufficient to determine cell quality. Therefore, post-processing the values ​​after measuring multiple CSI-RSs may be necessary. Methods for measuring cell quality can be differentiated depending on how the values ​​are post-processed. The following methods can be considered.

[0275] Method 1. A method of judging cell quality by averaging measured values ​​for N CSI-RS resources.

[0276] In method 1, the number of CSI-RS resources can be explicitly determined for each candidate cell and the measured values ​​can be averaged. The RRC parameter LTM-ReportContent has a parameter called noOfReportedRS-PerCell, which indicates how many RSs are reported for each cell. Based on this value, an explicit number of CSI-RS resources can be indicated for each cell, and the terminal can determine the quality of the candidate cell by averaging the measured values ​​for each CSI-RS. In this case, there is an advantage in that the ping-pong phenomenon that may occur when the measured value of one CSI-RS resource is good but the measured value of another CSI-RS resource is not good can be prevented. In this case, the N may be a value indicated by RRC / MAC-CE / DCI, etc., or determined by a prior agreement or agreement.

[0277] Method 2. A method of judging cell quality by averaging the measured values ​​for N CSI-RSs that exceed the threshold.

[0278] For Method 2, the information stored in CSI-ReportConfig, such as cri-RSRP, cri-SINR, cri-RSRP-index, or cri-SINR-index (measured later), can be utilized. The measured values ​​of the CSI-RS resources for each candidate cell are compared with a preset threshold, and only if the value is greater, the average is calculated to determine the quality of the candidate cell.

[0279] In this case, cell quality is measured only for beams that are actually used, which has the advantage of eliminating the need to calculate values ​​for beams that are not actually used. However, in this case, the number of CSI-RS resources exceeding the threshold may be very small. In this case, the base station can set a minimum number of CSI-RS resources.

[0280] Method 3. A method for selecting cell quality based on measured values ​​for the best CSI-RS resource.

[0281] Method 3, the simplest method, determines the best CSI-RS resource measurement value for each candidate cell and uses it as the cell quality indicator. Generally, if the measured value of a certain CSI-RS resource is large, the measured values ​​for other resources of the candidate cell will also tend to be large. Therefore, the best CSI-RS resource can be used as the cell quality indicator. This method has the advantage of low complexity because no separate calculation is required. However, since cell quality is estimated using a single value, reliability issues may arise. Therefore, if this method is used, a method / condition may be applied that requires reporting at least a certain number of CSI-RS resources for each candidate cell to improve reliability.

[0282] <SSB를 셀 품질 측정에 이용하는 방법>

[0283] This section describes how to utilize SSB for cell quality measurement. Since SSB does not have a one-to-one correspondence with CSI-RS, matching (or mapping) may be required to determine which CSI-RS resource corresponds to which SSB index. The matching method is described below.

[0284] Method 1. A method of setting the associated SSB for each resource when setting the CSI-RS resource in LTM, similar to the existing RRM.

[0285] In existing RRM operation, there is a parameter called associatedSSB in the RRC parameter CSI-RS-Resource-Mobility, which configures the SSB associated / related with the CSI-RS. Like RRM, LTM can also configure the SSB associated / related with the CSI-RS resource.

[0286] Table 13 illustrates information (associatedSSB) for setting the associated / related SSB for CSI-RS resources in LTM.

[0287] [Table 13]

[0288]

[0289] In this method, since the SSB index is clearly provided through the RRC parameter, the terminal can obtain the SSB index corresponding to the CSI-RS with low complexity.

[0290] Method 2. A method using SSB that shares QCL conditions using TCI states.

[0291] The UE can receive the TCI state ID of the candidate cell through the RRC parameter CandidateTCI-State IE. The CandidateTCI-State contains the LTM-QCL-Info parameter, which provides the QCL type of the corresponding SSB index and CSI-RS index in the corresponding TCI state ID. Based on this information, the UE can find the SSB that uses the same TCI state ID as the CSI-RS. When using this method, the UE can use this method without modifying any separate RRC parameters.

[0292] After matching each CSI-RS to an SSB, measuring cell quality through SSB can be done using a method similar to that of CSI-RS.

[0293] Method 1. A method of judging cell quality by averaging the measured values ​​for several SSBs.

[0294] For Method 1, the number of SSBs can be explicitly defined for each candidate cell and the measured values ​​can be averaged. The RRC parameter LTM-ReportContent has a parameter called noOfReportedRS-PerCell, which indicates how many RSs are reported for each cell. Based on this value, an explicit number of CSI-RS resources can be indicated for each cell, and the list defined in LTM-CSI-SSB-ResourceSet can be used to determine which SSBs belong to which cell IDs. The UE determines the quality of the candidate cell by averaging the measured values ​​for each SSB. This has the advantage of preventing the ping-pong phenomenon that can occur when the measured value of one CSI-RS resource is good but the measured value of another CSI-RS resource is not.

[0295] Method 2. A method of judging cell quality by averaging the quality of SSBs exceeding the threshold.

[0296] For Method 2, the information stored in CSI-ReportConfig, ssb-index-RSRP or ssb-index-SINR or ssb-index-RSRP-index or ssb-index-SINR-index (the measured value thereafter), is utilized. The measured value of the SSB for each candidate cell is compared with a preset threshold, and only if the value is larger, the average is taken to determine the quality of the candidate cell. In this case, since the cell quality is measured only for the beams that are actually used, there is an advantage in that there is no need to calculate values ​​for beams that are not actually used. However, in this case, there may be cases where the number of SSBs exceeding the threshold is very small, and the base station can set the minimum number of SSBs for this.

[0297] Method 3. Selecting cell quality based on best SSB measurement values.

[0298] Method 3, the simplest method, determines the best SSB measurement value for each candidate cell and uses it as the cell quality indicator. Generally, if the measured value of a certain SSB is large, the measured values ​​for other SSBs in that candidate cell will also tend to be large. Therefore, the best SSB can be used as the cell quality indicator. This method has the advantage of low complexity because it does not require separate calculations. However, because cell quality is determined based on a single value, reliability issues may arise. Therefore, if this method is used, a condition / method may be applied that requires reporting at least a certain number of SSBs for each candidate cell to improve reliability.

[0299] How to decide how many CRIs to report

[0300] Based on at least one of the methods described below, the terminal can determine how many CRIs to report for each candidate cell. In LTM according to existing standards (e.g., 3GPP NR Release 18), the number of RSs per cell and cell can be explicitly specified, up to a maximum of four. While existing standards describe SSB, this disclosure describes CSI-RS. The proposed method is as follows.

[0301] Method 1. Explicitly setting the number of resources included in a single report instance.

[0302] For CSI-RS, the number of CSI-RS resources can be configured in the LTM-ReportContent within the LTM-CSI-ReportConfig IE. However, unlike SSB, CSI-RS has a larger number of beams, and the maximum reportable number can increase compared to SSB. Therefore, if the base station cannot determine how many CRIs will be reported among multiple CSI-RS resources, the overhead of blind decoding may occur. Therefore, to avoid such blind decoding, it may be necessary to explicitly configure the resources included in a single report instance. For example, this information can be included in the report content of LTM.

[0303] Examples of upper-level parameters are shown in Table 14 below.

[0304] [Table 14]

[0305]

[0306] Method 2. Set a threshold and do not report values ​​below it.

[0307] The number of resources included in a single report instance can be determined by implicit rules. Examples of implicit rules may include the following:

[0308] For example, the UE receives a threshold value of RSRP (or SINR) from the gNB via RRC / MAC-CE / DCI, etc., and if the RSRP (or SINR) value measured for a resource of a triggered report is lower than the set threshold, the UE always does not include the resource in the report. The measured value used in this information can be, for example, cri-RSRP, cri-SINR, cri-RSRP-index, or cri-SINR-index (the measured value thereafter), which are information stored in CSI-ReportConfig.

[0309] The above method 2 can be used together with method 1. That is, the UE is instructed by the gNB via RRC / MAC-CE / DCI, etc., the number of resources to be included in a single report instance, and the UE reports the number of resources smaller than the value instructed by the gNB by excluding from the report the measured resources that do not exceed the threshold value optionally set in the report settings, etc.

[0310] Method 3. A method of not reporting CRIs below a certain value compared to the strongest (maximum) value.

[0311] The number of resources included in a single report instance is determined by implicit rules. At this time, embodiments of the implicit rules can consider the following. For example, the terminal can obtain the maximum value of the measured RSRP (or SINR). The terminal does not include in the report any measured value that exceeds a preset value (for example, in the case of RSRP, up to a value that can be expressed in 4 bits with a 2 dB step size based on the maximum value, and in the case of SINR, up to a value that can be expressed in 4 bits with a 1 dB step size based on the maximum value) based on the maximum value of the measured RSRP (or SINR). The measured value utilized in this information can utilize, for example, cri-RSRP, cri-SINR, cri-RSRP-index, or cri-SINR-index (hereinafter, the measured value), which are information stored in CSI-ReportConfig.

[0312] This method can be used in conjunction with Method 1. That is, the terminal can be instructed by the base station (gNB) via RRC / MAC-CE / DCI, etc., the number of resources to include in a single report instance, or the terminal can report a number of resources smaller than the number instructed by the gNB by excluding measured resources that exceed a threshold value optionally set in the report settings, etc.

[0313] Differential RSRP / SINR Representation for Multiple Resources

[0314] This paper describes a method for reducing reporting overhead by performing group-based reporting using differential values. Differential reporting involves transmitting an explicit value for the maximum value when multiple similar values ​​exist for a given measurement, and reporting a decreasing value (difference value) relative to a reference value (e.g., the maximum value) for the remaining values. This reduces the number of bits required for reporting. Depending on the scenario being applied, there are various methods for differential reporting.

[0315] Method 1. Using the best resource as a reference value for each candidate cell.

[0316] If the terminal does not report the resource set by dividing it by candidate cell, the terminal finds the measurement value with the maximum value among all resource sets and defines that measurement value as the reference value.

[0317] Other measured values ​​other than the reference value can be defined as differential values, which are the differences from the reference value. In this case, the terminal reports only the reference value and the differential value to the base station. When reporting is performed in this way, the base station finds the reference value with the maximum value for all resource sets in order to determine the quality of a candidate cell, and calculates the differential value for this to find the measurement value for the corresponding cell and corresponding CSI-RS that the base station is looking for. This may cause unnecessary calculations or the differential values ​​for each cell may be very large and exceed the range that can be expressed. Therefore, the best measured value can be set for each candidate cell, and the remaining values ​​can be expressed as differential values ​​and reported to the base station.

[0318] That is, when the LTM report configuration triggered by the gNB instructs the UE to report N cells and M cell-specific resources, and when the reporting is instructed to be group-based reporting, the UE reports direct values ​​of measured L1-RSRP, L1-SINR, etc. for the N cells, and differential values ​​of measured values ​​for each cell's resources based on the values.

[0319] Method 2. A method of using the best resource as a reference value for all CSI-RS resources.

[0320] This method explicitly expresses only the measurement value with the maximum value without distinguishing between candidate cells for all CSI-RS resources, and reports differential values ​​relative to the reference value for the remaining measurement values. The advantage of this method is that it can express the increased CSI-RS resources compared to SSB using a relatively small number of bits compared to other methods.

[0321] Reporting Contents

[0322] Below, we explain how to divide the reporting content and send each content in the CSI report. Ideally, the terminal should report exactly as many as the base station sets in the LTM-ReportContent IE's nrOfReportedCells and nrOfReportedRS-PerCell. However, when using a method such as reporting CRIs with measurement values ​​exceeding the aforementioned thresholds or CRIs with values ​​within a specific range based on the best measurement value, the terminal may report fewer CRIs than the set value.

[0323] For example, in method 1 of the above 'method for determining how many CRIs to report', the base station explicitly determines the number of CRIs to report to the terminal, but in method 2, a threshold is set in relation to the measured value, and measured values ​​below the threshold are not reported, so the number of CRIs included in the report may vary depending on the threshold or the measured value.

[0324] Alternatively, in the case of Method 3, since CRIs below a certain value compared to the strongest value are not reported, whether or not the other measured values ​​are included in the report may vary depending on the value measured as the strongest value, even if the other measured values ​​do not change.

[0325] If the number of resources included in a single report instance varies, the base station may need to perform blind decoding to receive the report. To prevent this, when performing LTM CSI reports, the terminal can perform separate encoding into two parts to ensure accurate reporting to the base station.

[0326] For example, information such as the number of candidate cells included in the report and / or the number of resources reported for each candidate cell can be encoded as the first part, and information such as the CRIs and the measured values ​​corresponding to each CRI (e.g., information such as L1-RSRP or L1-SINR) can be encoded as the second part.

[0327] Alternatively, the number of candidate cells included in the report and / or the number of resources reported for each candidate cell and / or the corresponding CRIs may be encoded as the first part, and the measured values ​​corresponding to each CRI (e.g., information such as L1-RSRP or L1-SINR) may be encoded as the second part.

[0328] In exceptional cases, if the terminal has no CRI to report to the base station through the above methods, etc., the first part may be reported as "none." Additionally, the CSI report may be configured as follows, for example:

[0329] As a first example, Part 1 CSI can be configured with the total number of CSI-RS resources (cell-independent), and Part 2 CSI can be configured with reports on CSI-RS resources per cell (RSRP / SINR).

[0330] As a second example, Part 1 CSI can be composed of the number of CSI-RS resource sets (information on the best n cells) + the number of resources per resource set, and Part 2 CSI can be composed of reports on CSI-RS resources per cell (RSRP / SINR).

[0331] The base station can indicate to the terminal the total number of CSI-RS resources, such as the maximum number of candidate cells that can be reported, and the number of CSI-RS resources per cell, by including them in the RRC parameter LTM-ReportContent as shown in Table 15.

[0332] [Table 15]

[0333]

[0334] Unlike the case where the CSI report is divided into two parts, when reporting the number of candidate cells and the number of CSI-RS resources per cell exactly as instructed by the base station, the number of CRI indices reported can be omitted. Alternatively, to match the number of CRI indices indicated by the base station, the aforementioned CRI selection method can be omitted and the number of CRIs set by the base station can be reported exactly as instructed.

[0335] II. Scenario 2. When the resource set is set independently of the cell.

[0336] Conventional standards define only one resource set per report. By configuring only one resource set per CSI-RS-based report, CSI reports for all candidate cells can be transmitted simultaneously. In this case, when a terminal compares CSI-RS resources, even if they are from different cells, they are all within the same resource set, allowing for simple value comparison without additional configuration.

[0337] Table 16 illustrates the measured RSRP for a single resource set.

[0338] [Table 16]

[0339]

[0340] In a case like Table 16, when reporting the top 4 resources according to the RSRP order, the reported resource IDs are 0, 2, 3, 4, which means that the resources of candidate cells 0, 1, and 2 will be selected. However, among the two resources of candidate cell ID 0, the other resource (resource ID 1) has an RSRP order of 6, and the RSRP values ​​of the two resources (resource ID 0 and resource ID 1) show a large difference, so it can be said that it has poor quality compared to other candidate cells in terms of cell quality. Therefore, in order to exclude candidate cell ID 0, such as in this example, from the reported resources, the quality of the candidate cells can be first judged in step 2 and then the reported resources can be selected. If the resource of RSRP order 1 is excluded, the reported resource IDs are 2, 3, 4, and 5, which means that the resources of candidate cells 1 and 2 will be selected.

[0341] However, this task can be quite complex. In this case, the terminal can report resources solely in RSRP order, without assessing cell quality. In this case, the top four resources can be reported in RSRP order. Then, the reported resource IDs would be 0, 2, 3, and 4, indicating that resources from candidate cells 0, 1, and 2 would be selected.

[0342] Since the above resource is for LTM, it will be configured by the LTM-CSI-ResourceConfig IE. Since the existing LTM-CSI-ResourceConfig defines a resource set only for SSB, a definition for CSI-RS must be included. For example, ltm-CSI-RS-ResourceSet-r19 can contain information about the CSI-RS resource set for LTM.

[0343] Since this scenario assumes that resource sets are configured for all beams, the CSI-RS resource set requires a list of candidate cell IDs and a list of resources to be included in the resource set. For example, this information could be included in cell ID and ltm-CSI-RS-ResourceList-19, respectively.

[0344] Table 17 illustrates an LTM-CSI-ResourceConfig IE according to the present disclosure.

[0345] [Table 17]

[0346]

[0347] After measuring each CSI-RS resource, the terminal can perform an LTM report including the measured value and CRI of each resource. The terminal can know which CSI-RS resource belongs to which cell ID through the list defined in LTM-CSI-RS-ResourceSet. In this scenario, since the CSI-RS resource and candidate cell are distinguished for each resource, there are two ways to select the CRI: i) a method of performing beam selection after cell quality-based selection in two steps, and ii) a method of selecting a beam regardless of the cell. If the cell quality-based selection is performed first, there is an advantage in that a high-quality beam with high reliability can be selected with low complexity through a refined sequence in preparation for cases where CSI-RS has a large number of beams compared to SSB.

[0348] First, the following method can be applied to cell quality ordering for each candidate cell.

[0349] 1) Method of using CSI-RS to measure cell quality.

[0350] 2) Method of using SSB to measure cell quality.

[0351] These two methods each have their own advantages. Using CSI-RS eliminates the need for associated SSB, allowing terminals to gauge cell quality solely through CSI-RS quality measurements. Using SSB offers the advantage of a wider beam than CSI-RS, allowing for more reliable measurement of overall cell quality. Each method is described in more detail below.

[0352] <CSI-RS를 셀 품질 측정에 이용하는 방법>

[0353] This paper describes how to use CSI-RS to measure cell quality. Because CSI-RS is a sharp beam, a single value is not sufficient to determine cell quality. Therefore, multiple CSI-RS measurements are required, followed by post-processing. Methods for measuring cell quality can be differentiated depending on how the values ​​are post-processed. The following methods can be considered.

[0354] Method 1. A method of judging cell quality by averaging measured values ​​for several CSI-RS resources.

[0355] For Method 1, the number of CSI-RS resources can be explicitly defined for each candidate cell and the measured values ​​can be averaged. The RRC parameter LTM-ReportContent has a parameter called noOfReportedRS-PerCell, which indicates how many RSs are reported for each cell. Based on this value, an explicit number of CSI-RS resources can be indicated for each cell, and the list defined in LTM-CSI-RS-ResourceSet can be used to determine which CSI-RS resource belongs to which cell ID. The terminal determines the quality of the candidate cell by averaging the measured values ​​for each CSI-RS. This has the advantage of preventing the ping-pong phenomenon that can occur when the measured value of one CSI-RS resource is good but the measured value of another CSI-RS resource is not.

[0356] Method 2. A method of judging cell quality by averaging the quality of CSI-RSs that exceed a threshold.

[0357] Method 2 utilizes the information stored in CSI-ReportConfig, such as cri-RSRP or cri-SINR or cri-RSRP-index or cri-SINR-index (measured thereafter). For each candidate cell, the measured value of the CSI-RS resource is compared with a preset threshold, and only if it is greater, the average is taken to determine the quality of the candidate cell. In this case, since the cell quality is measured only for the beams that are actually used, there is an advantage in that values ​​for beams that are not actually used do not need to be calculated. However, in this case, there may be cases where the number of CSI-RS resources exceeding the threshold is very small, and the base station can set the minimum number of CSI-RS resources in this case.

[0358] Method 3. A method for selecting cell quality based on measured values ​​for the best CSI-RS resource.

[0359] Method 3, the simplest method, can determine the best CSI-RS resource measurement value for each candidate cell and use it as the cell quality. In general, if the measured value of a certain CSI-RS resource is large, the measured values ​​for other resources of the candidate cell will also tend to be large, so the best CSI-RS resource can be used as the cell quality. This has the advantage of low complexity because no separate calculation is required, but reliability may be an issue because cell quality is estimated using a single value. Therefore, if this method is used, a condition / method may be applied that requires reporting at least a certain number of CSI-RS resources of each candidate cell to improve reliability.

[0360] <SSB를 셀 품질 측정에 이용하는 방법>

[0361] Next, we describe how to utilize SSB for cell quality measurement. Since SSB does not have a one-to-one correspondence with CSI-RS, matching is necessary to determine which CSI-RS resource corresponds to which SSB index. The following describes the methods for each matching.

[0362] Method 1. A method of setting the associated SSB for each resource when setting CSI-RS resources in LTM, similar to the existing RRM.

[0363] In the existing RRM operation, there is a parameter called associatedSSB in the RRC parameter CSI-RS-Resource-Mobility that configures the SSB associated / related with the CSI-RS. Like RRM, LTM can also configure the SSB associated / related with the CSI-RS resource. Table 18 shows an example of LTM-CSI-RS-ResourcesPerSet-r19 that includes the associatedSSB that configures the SSB associated / related with the CSI-RS.

[0364] [Table 18]

[0365]

[0366] In this case, since the SSB index is clearly provided through the RRC parameter, the terminal can obtain the SSB index corresponding to the CSI-RS with low complexity.

[0367] Method 2. A method using SSB that shares QCL conditions using TCI states.

[0368] The terminal can be provided with the TCI state ID of the candidate cell through the RRC parameter CandidateTCI-State IE. The CandidateTCI-State contains the LTM-QCL-Info parameter, which provides the QCL type of the corresponding SSB index and CSI-RS index in the corresponding TCI state ID. Based on this information, the terminal can find the SSB that uses the same TCI state ID as the CSI-RS, and when using this method, the terminal can use this method without modifying separate RRC parameters.

[0369] After matching each CSI-RS to an SSB, measuring cell quality through SSB can be done using a method similar to that of CSI-RS.

[0370] Method 1. A method of judging cell quality by averaging the measured values ​​for several SSBs.

[0371] For Method 1, the number of SSBs can be explicitly defined for each candidate cell and the measured values ​​can be averaged. The RRC parameter LTM-ReportContent has a parameter called noOfReportedRS-PerCell, which indicates how many RSs are reported for each cell. Based on this value, an explicit number of CSI-RS resources can be indicated for each cell, and the list defined in LTM-CSI-SSB-ResourceSet can be used to determine which SSB belongs to which cell ID. The UE determines the quality of the candidate cell by averaging the measured values ​​for each SSB. This has the advantage of preventing the ping-pong phenomenon that can occur when the measured value of one CSI-RS resource is good but the measured value of another CSI-RS resource is not.

[0372] Method 2. A method of judging cell quality by averaging the quality of SSBs that exceed a threshold.

[0373] For Method 2, the information stored in CSI-ReportConfig, ssb-index-RSRP or ssb-index-SINR or ssb-index-RSRP-index or ssb-index-SINR-index (the measured value thereafter), is utilized. The measured value of the SSB for each candidate cell is compared with a preset threshold, and only if the value is larger, the average is taken to determine the quality of the candidate cell. In this case, since the cell quality is measured only for the beams that are actually used, there is an advantage in that there is no need to calculate values ​​for beams that are not actually used. However, in this case, there may be cases where the number of SSBs exceeding the threshold is very small, and the base station can set the minimum number of SSBs for this.

[0374] Method 3. Selecting cell quality based on the best SSB measured value.

[0375] Method 3 is the simplest approach, determining the best SSB measurement value for each candidate cell and using it as the cell quality indicator. Typically, if a certain SSB has a large measured value, the other SSBs in that candidate cell will also tend to have large measured values, so the best SSB can be used as the cell quality indicator. This method has the advantage of lower complexity because it doesn't require separate calculations. However, because cell quality is assessed based on a single value, reliability issues may arise. Therefore, if this method is used, a method / condition that requires reporting at least a few SSBs for each candidate cell may be applied to improve reliability.

[0376] How to decide how many CRIs to report

[0377] First, we describe methods for selecting CRIs on a cell-by-cell basis. Based on each method, the terminal can determine how many CRIs to report for each candidate cell. 3GPP NR Release 18 LTM allows for explicit specification of each cell and the number of RSs per cell, up to four. However, since these existing standards focus on SSB, a new method needs to be determined for CSI-RS. The proposed method is as follows.

[0378] Method 1. The method where the number is explicitly set and the best few beams are reported.

[0379] Method 1 is very similar to SSB. CSI-RS can also be configured with the number of CSI-RS resources through LTM-ReportContent in the LTM-CSI-ReportConfig IE. However, unlike SSB, CSI-RS has a larger number of beams, and the maximum reportable number can be increased compared to SSB. Therefore, if the base station cannot know how many CRIs will be reported among multiple CSI-RS resources, the overhead of blind decoding may occur. Therefore, to avoid blind decoding, it may be necessary to explicitly configure the resources included in a single report instance. For example, this information can be included in the report content of LTM. Table 19 illustrates an LTM-ReportContent that includes information (nrOfReportedCSIRS-PerCell-r19) indicating how many best beams are reported.

[0380] [Table 19]

[0381]

[0382] Method 2. Set a threshold and do not report values ​​below it.

[0383] The number of resources included in a single report instance is determined by implicit rules. At this time, embodiments of the implicit rules can consider the following. For example, the UE receives a threshold value of RSRP (or SINR) from the gNB via RRC / MAC-CE / DCI, etc., and if the measured RSRP (or SINR) value for a resource of a triggered report is below the set threshold, the UE always does not include the resource in the report. The measured value utilized in this information can utilize, for example, cri-RSRP, cri-SINR, cri-RSRP-index, or cri-SINR-index (the measured value thereafter), which are information stored in CSI-ReportConfig.

[0384] Method 3. A method of not reporting CRIs below a certain value compared to the strongest value.

[0385] This method is divided into methods according to RSRP and SINR. For each cell, in the case of RSRP, only the CRI expressed up to 4-bit values ​​in 2-dB steps based on the maximum RSRP value is reported for CSI-RS resources with a smaller RSRP value, such as L1-RSRP, based on the maximum RSRP value. For each cell, in the case of SINR, only the CRI expressed up to 4-bit values ​​in 1-dB steps based on the maximum SINR value is reported for CSI-RS resources with a smaller SINR value, such as L1-SINR, based on the maximum SINR value.

[0386] Next, we describe a method for selecting CRIs independent of cells. Since the resource set is configured independently of cells, the UE performs measurements on all configured CSI-RS resources regardless of cell ID. Comparisons can then be performed across all CSI-RS resources. Based on each method, the UE can determine how many CRIs to report for all CSI-RS resources. 3GPP NR Release 18 LTM explicitly allows for up to four RSs per cell and for each cell. However, since these previous standards focused on SSB, a new method needs to be determined for CSI-RS. The proposed method is as follows.

[0387] Method 1. Explicitly setting the number and reporting the best few beams.

[0388] This method is very similar to SSB. CSI-RS can also set the number of CSI-RS resources in LTM-ReportContent within the LTM-CSI-ReportConfig IE. However, unlike SSB, CSI-RS has more beams, and the maximum reportable number can increase compared to SSB. Furthermore, to distinguish it from SSB, a new parameter needs to be set regardless of the cell. Table 20 shows an example of including information (nrOfReportedCSIRS-r19) setting the number of CSI-RS resources in LTM-ReportContent.

[0389] [Table 20]

[0390]

[0391] Method 2. Set a threshold and do not report values ​​below it.

[0392] The number of resources included in a single report instance is determined by implicit rules. At this time, embodiments of the implicit rules can consider the following. For example, the UE receives a threshold value of RSRP (or SINR) from the gNB via RRC / MAC-CE / DCI, etc., and if the measured RSRP (or SINR) value for a resource of a triggered report is below the set threshold, the UE always does not include the resource in the report. The measured value utilized in this information can utilize, for example, cri-RSRP, cri-SINR, cri-RSRP-index, or cri-SINR-index (the measured value thereafter), which are information stored in CSI-ReportConfig.

[0393] Method 3. A method of not reporting CRIs below a certain value compared to the strongest value.

[0394] The number of resources included in a single report instance is determined by implicit rules. At this time, embodiments of the implicit rules can consider the following. For example, the terminal can obtain the maximum value of the measured RSRP (or SINR). The terminal does not include in the report any measured value that exceeds a preset value (for example, in the case of RSRP, up to a value that can be expressed in 4 bits with a 2 dB step size based on the maximum value, and in the case of SINR, up to a value that can be expressed in 4 bits with a 1 dB step size based on the maximum value) based on the maximum value of the measured RSRP (or SINR). The measured value utilized in this information can utilize, for example, cri-RSRP, cri-SINR, cri-RSRP-index, or cri-SINR-index (hereinafter, the measured value), which are information stored in CSI-ReportConfig.

[0395] Differential RSRP / SINR Representation for Multiple Resources

[0396] This paper describes how group-based reporting can reduce reporting overhead through differential values. Differential reporting involves explicitly transmitting a value for the maximum value when multiple similar values ​​exist for a given measurement, and reporting a decreasing value (difference) relative to a reference value for the remaining values. This reduces the number of bits required for reporting. Differential reporting methods exist depending on the scenario being applied.

[0397] Method 1. Using the best resource as a reference value for each candidate cell.

[0398] If the terminal does not report resource sets by candidate cell, the terminal finds the maximum measurement value across all resource sets and defines it as the reference value. For measured values ​​other than the reference value, the terminal reports only the reference value and the differential value when defining the difference from the reference value as a differential value to the base station.

[0399] When reporting is performed in this manner, the base station must determine the quality of a candidate cell by finding a reference value for all resources and calculating a differential value for each to find the measurement value for the corresponding cell and CSI-RS. This can lead to unnecessary calculations, or the differential values ​​for each cell may be so large that they exceed the expressible range. Therefore, the best measurement value can be set for each candidate cell, and the remaining values ​​can be expressed as differential values ​​and reported to the base station.

[0400] Method 2. A method of using the best resource as a reference value for all CSI-RS resources.

[0401] This method explicitly expresses only the measurement value with the maximum value without distinguishing between candidate cells for all CSI-RS resources, and reports differential values ​​relative to a reference value for the remaining measurement values. The advantage of this method is that it can express the increased CSI-RS resources compared to SSB using a relatively small number of bits compared to other methods.

[0402] <Reporting Contents>

[0403] This explains how to divide the reporting content and send each content in a CSI report. Ideally, the terminal should report exactly as many as set by the base station, such as nrOfReportedCells and nrOfReportedRS-PerCell in the LTM-ReportContent IE. However, when using a method such as reporting CRIs with measurement values ​​exceeding the aforementioned thresholds or CRIs with values ​​within a specific range based on the best measurement value, the terminal may report fewer CRIs than the set value.

[0404] For example, in the case of the above 'method for determining how many CRIs to report', in method 1, the number of CRIs to be explicitly reported from the base station to the terminal is determined, but in the case of method 2, a threshold is set for the measured value and values ​​below the threshold are not reported, so the number of CRIs included in the report may vary depending on the threshold or the measured value.

[0405] Alternatively, in the case of Method 3, CRIs below a certain value relative to the strongest value are not reported, so whether they are included in the report may vary depending on the strongest measured value, even if other measured values ​​remain unchanged. If the number of resources included in a single report instance varies, the base station may have to perform blind decoding to receive the report.

[0406] To prevent this, when performing an LTM CSI report, the terminal can encode it into two parts separately to ensure accurate reporting to the base station. For example, the number of candidate cells included in the report and / or the number of reported resources for each candidate cell can be encoded in the first part, and the CRIs and the measured values ​​corresponding to each CRI (e.g., information such as L1-RSRP or L1-SINR) can be encoded in the second part.

[0407] Alternatively, the number of candidate cells included in the report and / or the number of reported resources for each candidate cell and / or the corresponding CRIs may be encoded as the first part, and the measured values ​​corresponding to each CRI (e.g., information such as L1-RSRP or L1-SINR) may be encoded as the second part.

[0408] In exceptional cases, if the terminal has no CRI to report to the base station through the above methods, the first part may be reported as "none." In addition to the above description, a CSI report can be configured as follows, for example:

[0409] As a first example, Part 1 CSI consists of the total number of CSI-RS resources (cell-independent), and Part 2 CSI consists of reports (RSRP / SINR) for CSI-RS resources for all cells.

[0410] As a second example, Part 1 CSI consists of the number of CSI-RS resources for each candidate cell (information on the best n cells) + the number of resources for each candidate cell, and Part 2 CSI consists of reports on CSI-RS resources for each cell (RSRP / SINR).

[0411] The base station can indicate the total number of CSI-RS resources, such as the maximum number of candidate cells that can be reported to the terminal and the number of CSI-RS resources per cell, by including them in the RRC parameter LTM-ReportContent. Table 21 illustrates an example of LTM-ReportContent that includes information on the total number of CSI-RS resources (nrOfReportedRS-r19).

[0412] [Table 21]

[0413]

[0414] Unlike the case where the CSI report is divided into two parts, when reporting the number of candidate cells and the number of CSI-RS resources per cell exactly as instructed by the base station, the number of CRI indices reported can be omitted. Alternatively, to match the number of CRI indices to the number instructed by the base station, the CRI selection method mentioned above can be omitted and the number of CRIs set by the base station can be reported exactly.

[0415] Figure 13 illustrates the signaling process for LTM.

[0416] Referring to Figure 13, the LTM procedure can be performed as follows.

[0417] The terminal is in RRC_CONNECTED state (S131).

[0418] 1. The terminal transmits a measurement report (e.g., MeasurementReport) message to the base station (S132). The base station determines the LTM settings and begins LTM preparation (S133).

[0419] 2. The base station transmits an RRC reset message (e.g., RRCReconfiguration) including LTM candidate settings to the terminal (S134).

[0420] 3. The terminal stores the LTM candidate settings and transmits an RRC reconfiguration complete message (e.g., RRCReconfigurationComplete) to the base station (S135).

[0421] 4a. The terminal performs downlink (DL) synchronization with the LTM candidate cell before receiving the cell switch command (S136). The terminal can activate and deactivate the TCI state of the LTM candidate cell according to a trigger from the base station.

[0422] 4b. Before receiving a cell switch command, the UE can perform UL synchronization with the LTM candidate cell by using terminal-based TA measurement (if configured) or by transmitting a preamble to the candidate cell according to a trigger from the base station (S137). If terminal-based TA measurement is configured, the UE acquires the TA value of the candidate cell through the measurement. Before receiving the cell switch command, the UE can perform early TA acquisition for the candidate cell at the request of the network. This is performed through a CFRA triggered by a PDCCH command of the source cell, after which the UE transmits a preamble toward the designated candidate cell. To minimize data interruption of the source cell due to the CFRA toward the candidate cell, the UE does not receive a random access response from the network for TA value acquisition, and the TA value of the candidate cell can be indicated in the cell switch command. The UE does not maintain a TA timer for the candidate cell, and the validity of the TA can be guaranteed depending on the network implementation.

[0423] 5. The terminal performs L1 measurements on the configured LTM candidate cells and transmits an L1 measurement report to the base station (S138-1). L1 measurements may be required as long as RRC reconfiguration (step 2) is applied.

[0424] 6. The base station decides to execute a cell switch to the target cell (S138-2) and transmits an LTM cell switch command MAC CE that triggers the cell switch, which includes a target configuration ID indicating a candidate configuration index of the target cell, beam(s) indicated by DL and UL TCI states, and a timing advance command for the target cell (if available) (S138-3). The terminal detaches from the source cell, switches to the target cell, and applies the candidate configuration indicated by the target configuration ID (S138-4).

[0425] 7. If the terminal does not have a valid TA of the target cell, it performs a random access procedure for the target cell (S138-5).

[0426] 8. The terminal completes the LTM cell switching procedure by transmitting an RRC reconfiguration complete message (e.g., RRCReconfigurationComplete) to the target cell (S139).

[0427] If the terminal performs the RA procedure in step 7, the LTM cell transition execution can be considered to have been successfully completed if the random access procedure is successfully completed.

[0428] For LTM without RACH, the terminal can consider the LTM cell switch execution to be completed successfully when the network determines that the first UL data has been successfully received.

[0429] Steps 4 to 8 described above can be performed multiple times in subsequent LTM cell switch executions using the LTM candidate settings provided in step 2.

[0430] The procedure on the wireless interface described in FIG. 13 can be applied to both intra-gNB-DU LTM and inter-gNB-DU LTM.

[0431] The cell switch command is carried over the MAC CE, which contains the information required to perform the LTM cell switching.

[0432] The initial synchronization, LTM cell switch execution, and LTM cell switch completion steps can be repeated without disabling other LTM candidate settings after each LTM cell switch is completed.

[0433] Figure 14 illustrates terminal operation.

[0434] Referring to FIG. 14, a user equipment (UE) receives LTM (L1 / L2 triggered mobility) CSI (Channel State Information) resource settings from a base station, and the LTM CSI resource settings are set so that CSI-RS resources of different candidate cells are included in one CSI-RS resource set (S141).

[0435] The above LTM CSI resource configuration may include a list of IDs (identifiers) of candidate cells and a list of resources included in a CSI-RS resource set. A terminal can identify CSI-RS resources included in a cell with a specific cell ID through the list of IDs and the list of resources.

[0436] According to an embodiment, the LTM CSI resource configuration may be configured by an RRC (radio resource control) message.

[0437] The terminal performs measurement on one CSI-RS (Channel State Information Reference Signal) resource set based on the above LTM CSI resource setting (S142).

[0438] The terminal transmits the results of the above measurement to the base station (S143).

[0439] The terminal receives a cell switch command from the base station through MAC CE (Medium Access Control Control Element) (S144).

[0440] The terminal can determine cell quality by measuring CSI-RS resources included in the above one CSI-RS resource set.

[0441] For example, a terminal can measure multiple CSI-RS resources for a specific candidate cell to generate measurement values, and average the measurement values ​​to determine cell quality for the specific candidate cell.

[0442] According to an embodiment, the terminal may measure multiple CSI-RS resources for a specific candidate cell to generate measurement values, and determine cell quality for the specific candidate cell by averaging only values ​​greater than a threshold among the measurement values.

[0443] At this time, the terminal may further receive information for setting the minimum value of the number of the plurality of CSI-RS resources for the specific candidate cell.

[0444] In some embodiments, the terminal may measure multiple CSI-RS resources for a specific candidate cell to generate measurement values, and determine cell quality for the specific candidate cell based on the best value among the measurement values. In connection with this process, the terminal may further receive information setting a minimum value of the number of the multiple CSI-RS resources for the specific candidate cell.

[0445] In some embodiments, the terminal may receive information setting the number of CRIs (CSI-RS Resource Indicators) to be reported in relation to a particular candidate cell.

[0446] According to an embodiment, the terminal may receive information for setting a threshold from the base station, and based on the information, skip measurement result reporting for CSI-RS resources having a measurement value less than the threshold.

[0447] The terminal can perform measurements on all CSI-RS resource sets included in the one CSI-RS resource set, regardless of the cell IDs (identifiers) of the different candidate cells, and then determine the cell quality for each candidate cell based on the measurement values.

[0448] The method described with reference to FIG. 14 can be used in conjunction with FIG. 13. For example, in '2. The base station transmits an RRC reconfiguration message (e.g., RRCReconfiguration) including LTM candidate settings to the terminal (S134)' of FIG. 13, the LTM CSI resource settings of FIG. 14 can be included in the RRC reconfiguration message. In '5. The terminal performs L1 measurement on the configured LTM candidate cell and transmits an L1 measurement report to the base station (S138-1). L1 measurement may need to be performed as long as RRC reconfiguration (step 2) is applied' of FIG. 13, the terminal can perform measurement based on the LTM CSI resource settings and report the measurement to the base station. The step (S138-3) in which the base station transmits the LTM cell switch command MAC CE that triggers the cell switch in FIG. 13 may correspond to the step (S144) in which the terminal receives the cell switch command from the base station via the MAC CE (Medium Access Control Control Element) in FIG. 14. The terminal in FIG. 14 may perform a RACH process after receiving the LTM cell switch command via the MAC CE. This process may correspond to S138-5 in FIG. 13. Thereafter, the terminal in FIG. 14 may transmit an LTM cell switch complete message to the base station, as in step S139.

[0449] According to the method according to the present disclosure, when performing an LTM operation, the operation can be performed based on CSI-RS rather than based on SSB as in the past. Specifically, the terminal performs measurements in a single CSI-RS resource set based on the LTM CSI resource configuration, and the single CSI-RS resource set can include CSI-RS resources of different candidate cells. Since the CSI-RS resources of different candidate cells exist in the same resource set, the terminal can simply compare the CSI values ​​of different candidate cells without separate configuration.

[0450] In addition, according to this specification, when using CSI-RS for LTM operation, by clearly specifying which CSI-RS to measure and report, how many CSI-RSs to measure and how to report, etc., ambiguity does not occur during LTM operation between the base station and the terminal.

[0451] Figure 15 illustrates signaling and operation between a base station and a terminal.

[0452] Referring to FIG. 15, the base station transmits LTM (L1 / L2 triggered mobility) CSI (Channel State Information) resource configuration to the terminal (S151). As described above, the LTM CSI resource configuration configures the CSI-RS resources of different candidate cells to be included in the single CSI-RS resource set.

[0453] For example, the LTM CSI resource configuration may include a list of IDs (identifiers) of candidate cells and a list of resources included in a CSI-RS resource set, and the terminal may identify CSI-RS resources included in a cell of a specific cell ID through the list of IDs and the list of resources.

[0454] The above LTM CSI resource settings can be set by an RRC (radio resource control) message.

[0455] Based on the above LTM CSI resource setting, the terminal performs measurement on one CSI-RS (Channel State Information Reference Signal) resource set (S152) and transmits the result of the measurement to the base station (S153).

[0456] The base station transmits a cell switch command to the terminal through MAC CE (Medium Access Control Control Element) (S154).

[0457] Then, the terminal performs a handover to a new cell (S155). The signaling process and operation of Fig. 15 can be referenced with Figs. 13 and 14.

[0458] Figure 16 illustrates a wireless device applicable to the present specification.

[0459] Referring to FIG. 16, the first wireless device (100) and the second wireless device (200) can transmit and receive wireless signals through various wireless access technologies (e.g., LTE, NR).

[0460] A first wireless device (100) includes at least one processor (102) and at least one memory (104), and may further include at least one transceiver (106) and / or at least one antenna (108). The at least one processor (102, hereinafter simply referred to as a processor) controls at least one memory (104, hereinafter simply referred to as a memory) and / or at least one transceiver (106, hereinafter simply referred to as a transceiver or a transceiver), and may be configured to implement the descriptions, functions, procedures, proposals, methods, and / or operational flowcharts disclosed in this document. 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 via 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 code including commands for performing the descriptions, functions, procedures, proposals, methods, and / or operation flowcharts disclosed in this document. 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 a wireless signal through one or more antennas (108). The transceiver (106) may include a transmitter and / or a receiver. The transceiver (106) may be used interchangeably with an RF (Radio Frequency) unit.In this specification, wireless device may also mean a communication modem / circuit / chip.

[0461] A processor (102) may be included in a terminal. The processor (102) receives an LTM CSI resource configuration from a base station, performs measurement in a CSI-RS resource set based on the LTM CSI resource configuration, transmits the measurement result to the base station, and receives a cell switch command from the base station via a MAC CE (Medium Access Control Control Element). In this process, the LTM CSI resource configuration configures the CSI-RS resources of different candidate cells to be included in the CSI-RS resource set. The specific operation thereof has been described with reference to FIGS. 13 to 15.

[0462] A second wireless device (200) includes at least one processor (202), at least one memory (204), and may further include at least one transceiver (206) and / or at least one antenna (208). The processor (202) controls the memory (204) and / or the transceiver (206), and may be configured to implement the descriptions, functions, procedures, proposals, methods, and / or operational flowcharts disclosed in this document. 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). In addition, 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 code including commands for performing the descriptions, functions, procedures, proposals, methods, and / or operation flowcharts disclosed in this document. Here, the processor (202) and the memory (204) may be part of a communication modem / circuit / chip designed to implement wireless communication technology (e.g., LTE, NR). The transceiver (206) may be connected to the processor (202) and may transmit and / or receive wireless signals via one or more antennas (208). The transceiver (206) may include a transmitter and / or a receiver. The transceiver (206) may be used interchangeably with an RF unit. In this specification, a wireless device may also mean a communication modem / circuit / chip.

[0463] The processor (202) may be included in a base station. The processor (202) transmits an LTM (L1 / L2 triggered mobility) CSI (Channel State Information) resource configuration to a terminal, receives a measurement result for a CSI-RS (Channel State Information Reference Signal) resource set from the terminal based on the LTM CSI resource configuration, and transmits a cell switch command to the terminal through a MAC CE (Medium Access Control Control Element), wherein the LTM CSI resource configuration sets CSI-RS resources of different candidate cells to be included in the one CSI-RS resource set. The specific operation thereof has been described with reference to FIGS. 13 to 15.

[0464] Hereinafter, the hardware elements of the wireless device (100, 200) will be described in more detail. Although not limited thereto, one or more protocol layers may be implemented by one or more processors (102, 202). For example, one or more processors (102, 202) may implement one or more layers (e.g., functional layers such as 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 operation flowcharts disclosed in this document. One or more processors (102, 202) may generate messages, control information, data, or information according to the descriptions, functions, procedures, proposals, methods, and / or operation flowcharts disclosed in this document. 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, proposals and / or methods disclosed herein, 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, proposals, methods and / or operational flowcharts disclosed herein.

[0465] 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 one or more processors (102, 202) may also be implemented by at least one computer-readable medium (CRM) containing instructions based on which at least one processor is executed.

[0466] For example, at least one computer-readable medium (CRM) including instructions that are executed by at least one processor performs the following operations: receiving an LTM CSI resource configuration from a base station; performing a measurement in one CSI-RS resource set based on the LTM CSI resource configuration; transmitting a result of the measurement to the base station; and receiving a cell switch command from the base station via a MAC CE (Medium Access Control Control Element). In this process, the LTM CSI resource configuration configures CSI-RS resources of different candidate cells to be included in the one CSI-RS resource set. The specific operations have been described with reference to FIGS. 13 to 15.

[0467] The descriptions, functions, procedures, suggestions, methods and / or operation flowcharts disclosed in this document may be implemented using firmware or software, and the firmware or software may be implemented to include modules, procedures, functions, etc. The descriptions, functions, procedures, suggestions, methods and / or operation flowcharts disclosed in this document may be implemented using firmware or software in the form of codes, instructions and / or sets of instructions. The firmware or software configured to perform the descriptions, functions, procedures, suggestions, methods and / or operation flowcharts disclosed in this document may be included in one or more processors (102, 202) or stored in one or more memories (104, 204) and executed by one or more processors (102, 202). The descriptions, functions, procedures, suggestions, methods and / or operation flowcharts disclosed in this document may be implemented using firmware or software in the form of codes, instructions and / or sets of instructions.

[0468] One or more memories (104, 204) may be coupled to one or more processors (102, 202) and may store various forms of data, signals, messages, information, programs, codes, instructions, and / or commands. The one or more memories (104, 204) may be configured as ROM, RAM, EPROM, flash memory, hard drives, registers, cache memory, computer-readable storage media, and / or combinations thereof. The one or more memories (104, 204) may be located internally and / or externally to the one or more processors (102, 202). Additionally, the one or more memories (104, 204) may be coupled to the one or more processors (102, 202) via various technologies, such as wired or wireless connections.

[0469] One or more transceivers (106, 206) can transmit user data, control information, wireless signals / channels, etc., as mentioned in the methods and / or flowcharts of this document, to one or more other devices. One or more transceivers (106, 206) can receive user data, control information, wireless signals / channels, etc., as mentioned in the descriptions, functions, procedures, proposals, methods and / or flowcharts of this document, from one or more other devices. For example, one or more transceivers (106, 206) can be connected 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, or the like, as referred to in the descriptions, functions, procedures, proposals, methods, and / or operational flowcharts disclosed herein, via one or more antennas (108, 208). In this document, one or more antennas may be multiple physical antennas or multiple logical antennas (e.g., antenna ports). One or more transceivers (106, 206) can 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 user data, control information, wireless signals / channels, etc. processed by one or more processors (102, 202) from baseband signals to RF band signals. For this purpose, one or more transceivers (106, 206) may include an (analog) oscillator and / or filter.

[0470] Figure 17 illustrates another example of a wireless device.

[0471] According to FIG. 17, the wireless device may include at least one processor (102, 202), at least one memory (104, 204), at least one transceiver (106, 206), and one or more antennas (108, 208).

[0472] The difference between the example of the wireless device described in FIG. 16 and the example of the wireless device in FIG. 17 is that in FIG. 16, the processor (102, 202) and the memory (104, 204) are separated, whereas in the example of FIG. 17, the memory (104, 204) is included in the processor (102, 202). For example, the processor and the memory may constitute a single chipset.

[0473] Fig. 18 illustrates an example of a signal processing module structure. Here, signal processing may be performed in the processor (102, 202) of Fig. 16.

[0474] Referring to FIG. 18, a transmission device (e.g., a processor, a processor and a memory, or a processor and a transceiver) within a terminal or a base station may include a scrambler (301), a modulator (302), a layer mapper (303), an antenna port mapper (304), a resource block mapper (305), and a signal generator (306).

[0475] A transmitting device can transmit one or more codewords. The coded bits within each codeword are scrambled by a scrambler (301) and transmitted over a physical channel. A codeword may also be referred to as a data string and may be equivalent to a transport block, which is a data block provided by the MAC layer.

[0476] The scrambled bits are modulated into complex-valued modulation symbols by a modulator (302). The modulator (302) can modulate the scrambled bits according to a modulation scheme and arrange them into complex-valued modulation symbols that represent positions on a signal constellation. There is no limitation on the modulation scheme, and m-PSK (m-Phase Shift Keying) or m-QAM (m-Quadrature Amplitude Modulation) can be used to modulate the encoded data. The modulator may be referred to as a modulation mapper.

[0477] The complex modulation symbols may be mapped to one or more transmission layers by a layer mapper (303). The complex modulation symbols on each layer may be mapped by an antenna port mapper (304) for transmission on an antenna port.

[0478] The resource block mapper (305) can map the complex modulation symbol for each antenna port to an appropriate resource element within a virtual resource block (VRB) allocated for transmission. The resource block mapper can map the VRB to a physical resource block (PRB) according to an appropriate mapping scheme. The resource block mapper (305) can assign the complex modulation symbol for each antenna port to an appropriate subcarrier and multiplex it according to the user.

[0479] The signal generator (306) can generate a complex-valued time domain OFDM symbol signal by modulating a complex modulation symbol, for example, an antenna-specific symbol, for each antenna port, with a specific modulation method, for example, an Orthogonal Frequency Division Multiplexing (OFDM) method. The signal generator can perform an Inverse Fast Fourier Transform (IFFT) on the antenna-specific symbol, and a Cyclic Prefix (CP) can be inserted into the time domain symbol on which the IFFT is performed. The OFDM symbol is transmitted to a receiving device through each transmitting antenna through digital-to-analog conversion, frequency uplink conversion, etc. The signal generator can include an IFFT module, a CP inserter, a Digital-to-Analog Converter (DAC), a frequency uplink converter, etc.

[0480] Fig. 19 illustrates another example of the signal processing module structure within a transmission device. Here, signal processing may be performed in a processor of a terminal / base station, such as the processor (102, 202) of Fig. 16.

[0481] Referring to FIG. 19, a transmission device (e.g., a processor, a processor and a memory, or a processor and a transceiver) in a terminal or a base station may include a scrambler (401), a modulator (402), a layer mapper (403), a precoder (404), a resource block mapper (405), and a signal generator (406).

[0482] The transmitting device can transmit coded bits within a codeword through a physical channel after scrambling the coded bits within the codeword by a scrambler (401).

[0483] The scrambled bits are modulated into complex modulation symbols by a modulator (402). The modulator can modulate the scrambled bits according to a predetermined modulation scheme and arrange them into complex modulation symbols representing positions on a signal constellation. There is no limitation on the modulation scheme, and pi / 2-BPSK (pi / 2-Binary Phase Shift Keying), m-PSK (m-Phase Shift Keying), or m-QAM (m-Quadrature Amplitude Modulation) can be used to modulate the encoded data.

[0484] The above complex modulation symbol can be mapped to one or more transmission layers by the layer mapper (403).

[0485] The complex modulation symbols on each layer can be precoded by the precoder (404) for transmission on the antenna ports. Here, the precoder may perform precoding after performing transform precoding on the complex modulation symbols. Alternatively, the precoder may perform precoding without performing transform precoding. The precoder (404) may process the complex modulation symbols in a MIMO manner according to multiple transmission antennas to output antenna-specific symbols and distribute the antenna-specific symbols to the corresponding resource block mapper (405). The output z of the precoder (404) can be obtained by multiplying the output y of the layer mapper (403) by the precoding matrix W of NХM. Here, N is the number of antenna ports and M is the number of layers.

[0486] The resource block mapper (405) maps the demodulation modulation symbol for each antenna port to the appropriate resource element within the virtual resource block allocated for transmission.

[0487] The resource block mapper (405) can assign complex modulation symbols to appropriate subcarriers and multiplex them according to the user.

[0488] The signal generator (406) can generate a complex-valued time domain OFDM (Orthogonal Frequency Division Multiplexing) symbol signal by modulating a complex modulation symbol with a specific modulation method, for example, OFDM. The signal generator (406) can perform an Inverse Fast Fourier Transform (IFFT) on an antenna-specific symbol, and a Cyclic Prefix (CP) can be inserted into the time domain symbol on which the IFFT has been performed. The OFDM symbol is transmitted to a receiving device through each transmitting antenna after going through digital-to-analog conversion, frequency upconversion, etc. The signal generator (406) can include an IFFT module, a CP inserter, a Digital-to-Analog Converter (DAC), a frequency uplink converter, etc.

[0489] The signal processing process of the receiving device may be configured in reverse order of the signal processing process of the transmitter. Specifically, the processor of the receiving device performs decoding and demodulation on a wireless signal received externally through the antenna port(s) of the transceiver. The receiving device may include a plurality of multiple receiving antennas, and each signal received through the receiving antenna is restored to a baseband signal and then multiplexed and MIMO demodulated to be restored to a data sequence originally intended to be transmitted by the transmitting device. The receiving device (1820) may include a signal restorer for restoring the received signal to a baseband signal, a multiplexer for combining and multiplexing the received and processed signals, and a channel demodulator for demodulating the multiplexed signal sequence into a corresponding codeword. The signal restorer, the multiplexer, and the channel demodulator may be configured as an integrated module performing their functions or as individual modules. More specifically, the signal restorer may include an analog-to-digital converter (ADC) that converts an analog signal into a digital signal, a CP remover that removes a CP from the digital signal, an FFT module that applies an FFT (fast Fourier transform) to a signal from which the CP has been removed to output a frequency domain symbol, and a resource element demapper / equalizer that restores the frequency domain symbol to an antenna-specific symbol. The antenna-specific symbol is restored to a transmission layer by a multiplexer, and the transmission layer is restored to a codeword that the transmitter intended to transmit by a channel demodulator.

[0490] FIG. 20 illustrates an example of a wireless communication device according to an implementation example of the present disclosure.

[0491] Referring to FIG. 20, a wireless communication device, for example, a terminal, may include at least one of a processor (2310) such as a digital signal processor (DSP) or a microprocessor, a transceiver (2335), a power management module (2305), an antenna (2340), a battery (2355), a display (2315), a keypad (2320), a global positioning system (GPS) chip (2360), a sensor (2365), a memory (2330), a subscriber identification module (SIM) card (2325), a speaker (2345), and a microphone (2350). There may be a plurality of antennas and processors.

[0492] The processor (2310) can implement the functions, procedures, and methods described in this specification. The processor (2310) of FIG. 20 may be the processor (102, 202) of FIG. 16.

[0493] Memory (2330) is connected to the processor (2310) and stores information related to the processor's operation. The memory may be located internally or externally to the processor and may be connected to the processor via various technologies, such as wired or wireless connections. The memory (2330) of FIG. 20 may be the memory (104, 204) of FIG. 16.

[0494] A user may input various types of information, such as a phone number, using various techniques, such as pressing buttons on a keypad (2320) or activating sound using a microphone (2350). The processor (2310) may receive and process the user's information and perform an appropriate function, such as dialing the entered phone number. In some scenarios, data may be retrieved from a SIM card (2325) or memory (2330) to perform the appropriate function. In some scenarios, the processor (2310) may display various types of information and data on a display (2315) for the user's convenience.

[0495] A transceiver (2335) is coupled to a processor (2310) and transmits and / or receives wireless signals, such as radio frequency (RF) signals. The processor may control the transceiver to initiate communication or transmit wireless signals containing various types of information or data, such as voice communication data. The transceiver includes a transmitter and a receiver for transmitting and receiving wireless signals. An antenna (2340) may facilitate the transmission and reception of wireless signals. In some implementations, upon receiving a wireless signal, the transceiver may forward and convert the signal to a baseband frequency for processing by the processor. The processed signal may be processed by various techniques, such as being converted into audible or readable information for output through a speaker (2345). The transceiver of FIG. 20 may be the transceiver (106, 206) of FIG. 16.

[0496] Although not shown in FIG. 20, various components, such as a camera and a Universal Serial Bus (USB) port, may be additionally included in the terminal. For example, the camera may be connected to the processor (2310).

[0497] Fig. 20 is only one implementation example for a terminal, and the implementation examples are not limited thereto. The terminal does not necessarily have to include all the elements of Fig. 20. For example, some components, such as a keypad (2320), a Global Positioning System (GPS) chip (2360), a sensor (2365), and a SIM card (2325), may not be essential elements, and in this case, may not be included in the terminal.

[0498] Fig. 21 illustrates a communication system (1) applied to this specification.

[0499] Referring to FIG. 21, a communication system (1) applied to the present specification includes a wireless device, a base station, and a network. Here, the wireless device refers to a device that performs communication using a wireless access technology (e.g., 5G NR (New RAT), LTE (Long Term Evolution)) and may be referred to as a communication / wireless / 5G device. Although not limited thereto, the wireless device may include a robot (100a), a vehicle (100b-1, 100b-2), an XR (eXtended Reality) device (100c), a hand-held device (100d), a home appliance (100e), an IoT (Internet of Things) device (100f), and an AI device / server (400). For example, the vehicle may include a vehicle equipped with a wireless communication function, an autonomous vehicle, a vehicle capable of performing vehicle-to-vehicle communication, etc. Here, the vehicle may include an Unmanned Aerial Vehicle (UAV) (e.g., a drone). XR devices include AR (Augmented Reality) / VR (Virtual Reality) / MR (Mixed Reality) devices, and can be implemented in the form of HMD (Head-Mounted Device), HUD (Head-Up Display) installed in a vehicle, television, smartphone, computer, wearable device, home appliance, digital signage, vehicle, robot, etc. Mobile devices can include smartphone, smart pad, wearable device (e.g., smart watch, smart glass), computer (e.g., laptop, etc.), etc. Home appliances can include TV, refrigerator, washing machine, etc. IoT devices can include sensors, smart meters, etc. For example, base stations and networks can also be implemented as wireless devices, and a specific wireless device (200a) can act as a base station / network node to other wireless devices.

[0500] Wireless devices (100a to 100f) can be connected to a network (300) via a base station (200). Artificial Intelligence (AI) technology can be applied to the wireless devices (100a to 100f), and the wireless devices (100a to 100f) can be connected to an AI server (400) via the network (300). The network (300) can be configured using a 3G network, a 4G (e.g., LTE) network, a 5G (e.g., NR) network, etc. The wireless devices (100a to 100f) can communicate with each other via the base station (200) / network (300), but can also communicate directly (e.g., sidelink communication) without going through the base station / network. For example, vehicles (100b-1, 100b-2) can communicate directly (e.g., V2V (Vehicle to Vehicle) / V2X (Vehicle to Everything) communication). In addition, IoT devices (e.g., sensors) can communicate directly with other IoT devices (e.g., sensors) or other wireless devices (100a to 100f).

[0501] Wireless communication / connection (150a, 150b, 150c) can be established between wireless devices (100a~100f) / base stations (200), and base stations (200) / base stations (200). Here, wireless communication / connection can be achieved through various wireless access technologies (e.g., 5G NR) such as uplink / downlink communication (150a), sidelink communication (150b) (or, D2D communication), and communication between base stations (150c) (e.g., relay, IAB (Integrated Access Backhaul). Through wireless communication / connection (150a, 150b, 150c), wireless devices and base stations / wireless devices, and base stations and base stations can transmit / receive wireless signals to each other. For example, wireless communication / connection (150a, 150b, 150c) can transmit / receive signals through various physical channels. To this end, at least some of various configuration information setting processes for transmitting / receiving wireless signals, various signal processing processes (e.g., channel encoding / decoding, modulation / demodulation, resource mapping / demapping, etc.), and resource allocation processes can be performed based on various proposals of the present specification.

[0502] Meanwhile, NR supports multiple numerologies (or subcarrier spacing (SCS)) to support various 5G services. For example, an SCS of 15 kHz supports a wide area in traditional cellular bands; an SCS of 30 kHz / 60 kHz supports dense urban areas, lower latency, and wider carrier bandwidth; and an SCS of 60 kHz or higher supports a bandwidth greater than 24.25 GHz to overcome phase noise.

[0503] The NR frequency band can be defined by two types of frequency ranges (FR1, FR2). The numerical values ​​of the frequency ranges can be changed, and for example, the frequency ranges of the two types (FR1, FR2) can be as shown in Table 22 below. For convenience of explanation, among the frequency ranges used in the NR system, FR1 can mean the "sub 6 GHz range", and FR2 can mean the "above 6 GHz range" and can be called millimeter wave (mmW).

[0504] [Table 22]

[0505]

[0506] As described above, the numerical value of the frequency range of the NR system can be changed. For example, FR1 may include a band from 410 MHz to 7125 MHz, as shown in Table 23 below. For example, FR1 may include a frequency band above 6 GHz (or 5850, 5900, 5925 MHz, etc.). For example, the frequency band above 6 GHz (or 5850, 5900, 5925 MHz, etc.) included within FR1 may include an unlicensed band. The unlicensed band may be used for various purposes, such as for communications for vehicles (e.g., autonomous driving).

[0507] [Table 23]

[0508]

[0509] The claims set forth in this specification may be combined in various ways. For example, the technical features of the method claims of this specification may be combined and implemented as a device, and the technical features of the device claims of this specification may be combined and implemented as a method. Furthermore, the technical features of the method claims and the technical features of the device claims of this specification may be combined and implemented as a device, and the technical features of the method claims and the technical features of the device claims of this specification may be combined and implemented as a method.

Claims

1. In the method, The terminal (user equipment: UE) receives LTM (L1 / L2 triggered mobility) CSI (Channel State Information) resource settings from the base station, The above terminal performs measurement in one CSI-RS (Channel State Information Reference Signal) resource set based on the LTM CSI resource setting, The terminal transmits the result of the measurement to the base station, and The terminal receives a cell switch command from the base station through a MAC CE (Medium Access Control Control Element). A method characterized in that the above LTM CSI resource configuration is configured such that CSI-RS resources of different candidate cells are included in the one CSI-RS resource set.

2. A method according to claim 1, characterized in that the LTM CSI resource configuration includes a list of IDs (identifiers) of candidate cells and a list of resources included in a CSI-RS resource set.

3. A method characterized in that, in the second paragraph, the CSI-RS resources included in a cell can be identified through the list of IDs and the list of resources.

4. A method according to claim 1, characterized in that the LTM CSI resource setting is set by an RRC (radio resource control) message.

5. A method according to claim 1, characterized in that the terminal determines cell quality by measuring CSI-RS resources included in the one CSI-RS resource set.

6. A method according to claim 1, wherein the terminal measures a plurality of CSI-RS resources for a specific candidate cell to generate measurement values, and averages the measurement values ​​to determine cell quality for the specific candidate cell.

7. A method according to claim 1, wherein the terminal measures a plurality of CSI-RS resources for a specific candidate cell to generate measurement values, and determines cell quality for the specific candidate cell by averaging only values ​​greater than a threshold among the measurement values.

8. A method according to claim 7, characterized in that the terminal receives information for setting the minimum value of the number of the plurality of CSI-RS resources for the specific candidate cell.

9. A method according to claim 1, wherein the terminal measures a plurality of CSI-RS resources for a specific candidate cell to generate measurement values, and determines cell quality for the specific candidate cell based on a best value among the measurement values.

10. A method according to claim 9, characterized in that the terminal receives information for setting the minimum value of the number of the plurality of CSI-RS resources for the specific candidate cell.

11. A method according to claim 1, characterized in that the terminal receives information setting the number of CRI (CSI-RS Resource Indicator) to be reported in relation to a specific candidate cell.

12. In the first paragraph, the terminal receives information for setting a threshold from the base station, A method characterized in that, based on the above information, measurement result reporting is skipped for CSI-RS resources having measurement values ​​less than the threshold.

13. A method according to claim 1, wherein the terminal performs measurement on all CSI-RS resource sets included in the one CSI-RS resource set, regardless of the cell IDs (identifiers) of the different candidate cells, and then determines the cell quality for each candidate cell based on the measurement values.

14. The terminal is, At least one transceiver; At least one memory; and At least one processor operably coupled with said at least one memory and said at least one transceiver, wherein said at least one memory comprises instructions that are executed by said at least one processor to perform operations, The above actions are, Receive LTM (L1 / L2 triggered mobility) CSI (Channel State Information) resource settings from the base station, Based on the above LTM CSI resource settings, measurements are performed on a set of CSI-RS (Channel State Information Reference Signal) resources, Transmit the results of the above measurement to the base station, and Including receiving a cell switch command from the above base station through a MAC CE (Medium Access Control Control Element), A terminal characterized in that the above LTM CSI resource setting is set so that CSI-RS resources of different candidate cells are included in the one CSI-RS resource set.

15. A terminal according to claim 14, wherein the LTM CSI resource configuration includes a list of IDs (identifiers) of candidate cells and a list of resources included in a CSI-RS resource set.

16. A terminal characterized in that, in the 15th paragraph, the CSI-RS resources included in a cell can be identified through the list of IDs and the list of resources.

17. A terminal according to claim 14, characterized in that the LTM CSI resource setting is set by an RRC (radio resource control) message.

18. In the 14th paragraph, the terminal is characterized in that the terminal determines cell quality by measuring CSI-RS resources included in the one CSI-RS resource set.

19. In the 14th paragraph, the terminal is characterized in that the terminal measures a plurality of CSI-RS resources for a specific candidate cell to generate measurement values, and averages the measurement values ​​to determine cell quality for the specific candidate cell.

20. In the 14th paragraph, the terminal is characterized in that, for a specific candidate cell, the terminal measures a plurality of CSI-RS resources to generate measurement values, and determines the cell quality for the specific candidate cell by averaging only values ​​greater than a threshold among the measurement values.

21. In paragraph 20, the terminal is characterized in that it receives information for setting the minimum value of the number of the plurality of CSI-RS resources for the specific candidate cell.

22. In the 14th paragraph, the terminal is characterized in that the terminal generates measurement values ​​by measuring a plurality of CSI-RS resources for a specific candidate cell, and determines the cell quality for the specific candidate cell based on the best value among the measurement values.

23. In paragraph 22, the terminal is characterized in that it receives information for setting the minimum value of the number of the plurality of CSI-RS resources for the specific candidate cell.

24. A method according to claim 14, characterized in that the terminal receives information setting the number of CRI (CSI-RS Resource Indicator) to be reported in relation to a specific candidate cell.

25. In the 14th paragraph, information for setting a threshold is received from the base station, A method characterized in that, based on the above information, measurement result reporting is skipped for CSI-RS resources having measurement values ​​less than the threshold.

26. In the 14th paragraph, the terminal performs measurement on all CSI-RS resource sets included in the one CSI-RS resource set, regardless of the cell IDs (identifiers) of the different candidate cells, and then determines the cell quality for each candidate cell based on the measurement values.

27. The device, At least one memory; and At least one processor operably coupled to at least one memory, wherein said at least one memory comprises instructions that are executed by said at least one processor to perform operations, The above actions are, Receive LTM (L1 / L2 triggered mobility) CSI (Channel State Information) resource settings from the base station, Based on the above LTM CSI resource settings, measurements are performed on a set of CSI-RS (Channel State Information Reference Signal) resources, Transmit the results of the above measurement to the base station, and Including receiving a cell switch command from the above base station through a MAC CE (Medium Access Control Control Element), A device characterized in that the above LTM CSI resource setting is set so that CSI-RS resources of different candidate cells are included in the one CSI-RS resource set.

28. At least one computer readable medium (CRM) containing instructions based on being executed by at least one processor, An operation to receive LTM (L1 / L2 triggered mobility) CSI (Medium Access Control) resource settings from a base station. An operation of performing a measurement on a set of CSI-RS (Channel State Information Reference Signal) resources based on the above LTM CSI resource settings. An operation of transmitting the results of the above measurement to the base station, and Including an operation of receiving a cell switch command from the above base station through a MAC CE (Medium Access Control Control Element), The above LTM CSI resource setting is a CRM characterized in that the CSI-RS resources of different candidate cells are set to be included in the one CSI-RS resource set.

29. In the method, The base station transmits LTM (L1 / L2 triggered mobility) CSI (Channel State Information) resource settings to the terminal, The base station receives the measurement result for one CSI-RS (Channel State Information Reference Signal) resource set based on the LTM CSI resource setting from the terminal, and The above base station transmits a cell switch command to the terminal through MAC CE (Medium Access Control Control Element), A method characterized in that the above LTM CSI resource configuration is configured such that CSI-RS resources of different candidate cells are included in the one CSI-RS resource set.

30. The base station, At least one transceiver; At least one memory; and At least one processor operably coupled with said at least one memory and said at least one transceiver, wherein said at least one memory comprises instructions that are executed by said at least one processor to perform operations, The above actions are, The above base station transmits LTM (L1 / L2 triggered mobility) CSI (Channel State Information) resource settings to the terminal, The base station receives the measurement result for one CSI-RS (Channel State Information Reference Signal) resource set based on the LTM CSI resource setting from the terminal, and Including an operation in which the base station transmits a cell switch command to the terminal through a MAC CE (Medium Access Control Control Element), A base station characterized in that the above LTM CSI resource setting is set so that CSI-RS resources of different candidate cells are included in the one CSI-RS resource set.

Images