WO2021221183A1 - Beam management method using reflection module - Google Patents

Abstract

Disclosed is a beam management method using a reflection module. A method according to one embodiment of the present specification can provide an effective beam management service for a terminal located in a shadow area, by: transmitting, by a base station (BS), a synchronization signal for downlink synchronization in a first window; transmitting, by the BS, a request to change a reflection pattern of a reflection module located apart from the BS in a start point of a second window after the first window; changing, by the reflection module, the reflection pattern upon receiving the request; and when a condition set in the second window is satisfied, transmitting, by the BS, the synchronization signal for the downlink synchronization and information on the reflection module to a user equipment (UE) through the reflection module. A base station, a terminal, and a reflection module of the present specification may be associated with an artificial intelligence module, a drone (unmanned aerial vehicle (UAV)), a robot, an augmented reality (AR) device, a virtual reality (VR) device, devices related to 5G services, etc.

Description

Beam management method using reflection module

The present specification relates to a beam management method using a reflection module.

For large-capacity data transmission, a high-frequency (eg, mmWave, THz) band, which is easy to secure a wideband frequency resource, may be used. However, compared to the low frequency band, the high frequency band has a large path loss and propagation characteristics with high straightness.

Therefore, in order to overcome path loss, the use of beam forming technology is essential, and securing LOS (line of sight) between the base station and the terminal due to the strong straightness characteristic is to improve the coverage and quality of the received signal. desirable.

Meanwhile, since a wireless communication system transmits a signal using a beam formed by beamforming in a high frequency band, a shadow area to which the beam does not reach may occur depending on the position of the receiver.

SUMMARY OF THE INVENTION The present specification aims to solve the above-mentioned needs and/or problems.

Another object of the present specification is to implement a beam management method using a reflection module capable of providing an LIS capable of changing a beam direction in a shaded area.

In addition, the present specification provides a beam management method using a reflection module capable of determining a reflection pattern of a reflection module capable of improving a reception channel environment of a terminal in a wireless communication system to which a reflection module (eg, Large Intelligence Surface, LIS) is applied. aims to implement.

In addition, an object of the present specification is to implement a beam management method using a reflection module that can provide a transmission beam of a base station and a reflection pattern of a reflection module in a minimum time in order to improve the reception channel environment of the terminal.

In addition, an object of the present specification is to implement a beam management method using a reflection module capable of searching for an optimal beam pattern through a control link between a base station having a low overhead and a reflection module.

A beam management method according to an embodiment of the present specification includes: transmitting, by a base station (BS), a synchronization signal for downlink synchronization in a first window; Transmitting a request to change the reflection pattern of the reflection module located spaced apart from the BS at a starting point; Changing the reflection pattern when the reflection module receives the request; and transmitting, by the BS, a synchronization signal for downlink synchronization and information on the reflection module to a user equipment (UE) through the reflection module when the condition set in the second window is satisfied.

In addition, the set condition may include a first condition in which the BS receives a response to the request for changing the reflection pattern and/or a second condition in which a set time elapses after transmitting the request. .

In addition, the synchronization signal may be an A6G (above 6GHz) synchronization signal.

Also, the information on the reflection module may be transmitted to the reflection module through a control link provided between the BS and the reflection module.

Also, the information on the reflection module may be a reflection module index indicating the reflection module.

In addition, the synchronization signal and the reflective module index may be transmitted from a direction in which the reflection module is located, and the reflection module index may be an index indicating a reflection module located in the direction.

Also, when the second window is terminated, the BS may increase the value of the reflection module index.

In addition, when the value of the reflection module index reaches the maximum value, the BS, performing an initial beam setting between the BS and the UE; may further include.

In addition, if it is determined that there is support by the reflection module based on the initial beam setting result, in the third window, the BS transmits one or more narrow beam indexes for adjusting the reflection pattern to the reflection module step; transmitting one or more reference signals associated with the narrow beam index; generating, by the UE, a channel state report based on the one or more reference signals, and transmitting the channel state report to the BS: the BS receives a maximum signal based on the channel state report The method may further include; determining one beam pair indicating strength).

In addition, the one or more reference signals are divided for each of the one or more narrow beam indexes, and the transmitting of the reference signal includes, when a specific narrow beam index is transmitted to the reflection module, a reference associated with the specific narrow beam index A signal may be transmitted to the UE.

Also, the at least one reference signal may be transmitted based on a fixed base station beam index in the third window.

Also, the at least one reference signal may be an A6G band signal.

In addition, the channel state report may be a signal of any one of the A6G band and the B6G band.

Further, the one or more narrow beam indexes may be transmitted to the reflection module through a control link provided between the BS and the reflection module.

A beam management method according to another embodiment of the present specification includes: receiving a synchronization signal for downlink synchronization from a BS in a first window; and receiving, through the reflection module, the synchronization signal provided from the BS and information about the reflection module in a second window that is distinct from the first window.

The effect of the beam management method using the reflection module according to an embodiment of the present specification will be described as follows.

The present specification may provide an LIS capable of changing the direction of a beam in a shaded area.

In addition, the present specification may determine a reflection pattern of a reflection module capable of improving a reception channel environment of a terminal in a wireless communication system to which a reflection module (eg, Large Intelligence Surface, LIS) is applied.

In addition, the present specification can provide the transmission beam of the base station and the reflection pattern of the reflection module in a minimum time in order to improve the reception channel environment of the terminal.

In addition, the present specification may search for an optimal beam pattern through a control link between a base station having a low overhead and a reflection module.

The effects obtainable in the present specification are not limited to the above-mentioned effects, and other effects not mentioned will be clearly understood by those of ordinary skill in the art to which this specification belongs from the description below. .

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are included as a part of the detailed description to help the understanding of the present specification, provide embodiments of the present specification, and together with the detailed description, explain the technical features of the present specification.

1 illustrates a block diagram of a wireless communication system to which the methods proposed in the present specification can be applied.

2 shows an example of a signal transmission/reception method in a wireless communication system.

3 shows an example of basic operations of a user terminal and a 5G network in a 5G communication system.

4 illustrates SSB transmission.

5 shows an example of beamforming using SSB and CSI-RS.

6 is a flowchart illustrating an example of a DL BM process using SSB.

7 shows another example of a DL BM process using CSI-RS.

8 is a flowchart illustrating an example of a process of determining a reception beam of a UE.

9 is a flowchart illustrating an example of a transmission beam determination process of the BS.

FIG. 10 shows an example of resource allocation in time and frequency domains related to the operation of FIG. 7 .

11 shows an example of a UL BM process using SRS.

12 is a flowchart illustrating an example of a UL BM process using SRS.

13 is a diagram for explaining an LIS applied to a wireless communication system according to an embodiment of the present specification.

14 is a conceptual diagram of a beam management method using a reflection module.

15 is a flowchart of a beam management method according to an embodiment of the present specification.

16 is a flowchart of a beam management method according to an embodiment of the present specification.

17 is a sequence diagram of a beam search method according to an embodiment of the present specification.

FIG. 18 is a diagram for exemplarily explaining the beam search method of FIG. 17 .

19 is a view for explaining a beam tracking method according to an embodiment of the present specification.

20 and 21 are diagrams for explaining the beam tracking method of FIG. 19 by way of example.

22 is an embodiment of a wireless communication system according to an embodiment of the present specification.

Hereinafter, the embodiments disclosed in the present specification will be described in detail with reference to the accompanying drawings, but the same or similar components are assigned the same reference numbers regardless of reference numerals, and redundant description thereof will be omitted. The suffixes "module" and "part" for the components used in the following description are given or mixed in consideration of only the ease of writing the specification, and do not have a meaning or role distinct from each other by themselves. In addition, in describing the embodiments disclosed in the present specification, if it is determined that detailed descriptions of related known technologies may obscure the gist of the embodiments disclosed in the present specification, the detailed description thereof will be omitted. In addition, the accompanying drawings are only for easy understanding of the embodiments disclosed in the present specification, and the technical spirit disclosed herein is not limited by the accompanying drawings, and all changes included in the spirit and scope of the present specification , should be understood to include equivalents or substitutes.

Terms including an ordinal number, such as first, second, etc., may be used to describe various elements, but the elements are not limited by the terms. The above terms are used only for the purpose of distinguishing one component from another.

When a component is referred to as being “connected” or “connected” to another component, it is understood that the other component may be directly connected or connected to the other component, but other components may exist in between. it should be On the other hand, when it is said that a certain element is "directly connected" or "directly connected" to another element, it should be understood that no other element is present in the middle.

The singular expression includes the plural expression unless the context clearly dictates otherwise.

In the present application, terms such as "comprises" or "have" are intended to designate that a feature, number, step, operation, component, part, or combination thereof described in the specification exists, but one or more other features It should be understood that this does not preclude the existence or addition of numbers, steps, operations, components, parts, or combinations thereof.

A. Example UE and 5G network block diagram

1 illustrates a block diagram of a wireless communication system to which the methods proposed in the present specification can be applied.

Referring to FIG. 1 , a device (AI device) including an AI module may be defined as a first communication device ( 910 in FIG. 1 ), and a processor 911 may perform detailed AI operations.

A second communication device ( 920 in FIG. 1 ) may perform a 5G network including another device (AI server) that communicates with the AI device, and the processor 921 may perform detailed AI operations.

The 5G network may be represented as the first communication device, and the AI device may be represented as the second communication device.

For example, the first communication device or the second communication device may include a base station, a network node, a transmitting terminal, a receiving terminal, a wireless device, a wireless communication device, a vehicle, a vehicle equipped with an autonomous driving function, and a connected car. ), drone (Unmanned Aerial Vehicle, UAV), AI (Artificial Intelligence) module, robot, AR (Augmented Reality) device, VR (Virtual Reality) device, MR (Mixed Reality) device, hologram device, public safety device, MTC device , IoT devices, medical devices, fintech devices (or financial devices), security devices, climate/environmental devices, devices related to 5G services, or other devices related to the 4th industrial revolution field.

For example, a terminal or user equipment (UE) includes a mobile phone, a smart phone, a laptop computer, a digital broadcasting terminal, personal digital assistants (PDA), a portable multimedia player (PMP), a navigation system, and a slate PC. (slate PC), tablet PC (tablet PC), ultrabook (ultrabook), wearable device (e.g., watch-type terminal (smartwatch), glass-type terminal (smart glass), HMD (head mounted display)) and the like. For example, the HMD may be a display device worn on the head. For example, an HMD may be used to implement VR, AR or MR. For example, the drone may be a flying vehicle that does not ride by a person and flies by a wireless control signal. For example, the VR device may include a device that implements an object or a background of a virtual world. For example, the AR device may include a device that implements by connecting an object or background in the virtual world to an object or background in the real world. For example, the MR device may include a device that implements a virtual world object or background by fusion with a real world object or background. For example, the hologram device may include a device for realizing a 360-degree stereoscopic image by recording and reproducing stereoscopic information by utilizing an interference phenomenon of light generated by the meeting of two laser beams called holography. For example, the public safety device may include an image relay device or an image device that can be worn on a user's body. For example, the MTC device and the IoT device may be devices that do not require direct human intervention or manipulation. For example, the MTC device and the IoT device may include a smart meter, a bending machine, a thermometer, a smart light bulb, a door lock, or various sensors. For example, a medical device may be a device used for the purpose of diagnosing, treating, alleviating, treating, or preventing a disease. For example, a medical device may be a device used for the purpose of diagnosing, treating, alleviating or correcting an injury or disorder. For example, a medical device may be a device used for the purpose of examining, replacing, or modifying structure or function. For example, the medical device may be a device used for the purpose of controlling pregnancy. For example, the medical device may include a medical device, a surgical device, an (ex vivo) diagnostic device, a hearing aid, or a device for a procedure. For example, the security device may be a device installed to prevent a risk that may occur and maintain safety. For example, the security device may be a camera, CCTV, recorder or black box. For example, the fintech device may be a device capable of providing financial services such as mobile payment.

Referring to FIG. 1 , a first communication device 910 and a second communication device 920 include a processor 911,921, a memory 914,924, and one or more Tx/Rx RF modules (radio frequency module, 915,925). , including Tx processors 912 and 922 , Rx processors 913 and 923 , and antennas 916 and 926 . Tx/Rx modules are also called transceivers. Each Tx/Rx module 915 transmits a signal via a respective antenna 926 . The processor implements the functions, processes and/or methods salpinned above. The processor 921 may be associated with a memory 924 that stores program code and data. Memory may be referred to as a computer-readable medium. More specifically, in DL (communication from a first communication device to a second communication device), the transmit (TX) processor 912 implements various signal processing functions for the L1 layer (ie, the physical layer). The receive (RX) processor implements the various signal processing functions of L1 (ie, the physical layer).

The UL (second communication device to first communication device) is handled in the first communication device 910 in a manner similar to that described with respect to the receiver function in the second communication device 920 . Each Tx/Rx module 925 receives a signal via a respective antenna 926 . Each Tx/Rx module provides an RF carrier and information to the RX processor 923 . The processor 921 may be associated with a memory 924 that stores program code and data. Memory may be referred to as a computer-readable medium.

B. Signal transmission/reception method in wireless communication system

2 is a diagram illustrating an example of a signal transmission/reception method in a wireless communication system.

Referring to FIG. 2 , the UE performs an initial cell search operation such as synchronizing with the BS when the power is turned on or a new cell is entered ( S201 ). To this end, the UE receives a primary synchronization channel (P-SCH) and a secondary synchronization channel (S-SCH) from the BS, synchronizes with the BS, and acquires information such as cell ID can do. In the LTE system and the NR system, the P-SCH and the S-SCH are called a primary synchronization signal (PSS) and a secondary synchronization signal (SSS), respectively. After the initial cell discovery, the UE may receive a physical broadcast channel (PBCH) from the BS to obtain broadcast information in the cell. Meanwhile, the UE may check the downlink channel state by receiving a downlink reference signal (DL RS) in the initial cell search step. After the initial cell search, the UE receives a physical downlink control channel (PDCCH) and a physical downlink shared channel (PDSCH) according to information carried on the PDCCH to obtain more specific system information. It can be done (S202).

On the other hand, when there is no radio resource for the first access to the BS or signal transmission, the UE may perform a random access procedure (RACH) to the BS (steps S203 to S206). To this end, the UE transmits a specific sequence as a preamble through a physical random access channel (PRACH) (S203 and S205), and a random access response to the preamble through the PDCCH and the corresponding PDSCH (random access response, RAR) message may be received (S204 and S206). In the case of contention-based RACH, a contention resolution procedure may be additionally performed.

After performing the process as described above, the UE receives PDCCH/PDSCH (S207) and a physical uplink shared channel (PUSCH)/physical uplink control channel as a general uplink/downlink signal transmission process. Uplink control channel, PUCCH) transmission (S208) may be performed. In particular, the UE receives downlink control information (DCI) through the PDCCH. The UE monitors a set of PDCCH candidates in monitoring opportunities set in one or more control element sets (CORESETs) on a serving cell according to corresponding search space configurations. The set of PDCCH candidates to be monitored by the UE is defined in terms of search space sets, which may be a common search space set or a UE-specific search space set. CORESET consists of a set of (physical) resource blocks with a time duration of 1 to 3 OFDM symbols. The network may configure the UE to have multiple CORESETs. The UE monitors PDCCH candidates in one or more search space sets. Here, monitoring means trying to decode PDCCH candidate(s) in the search space. If the UE succeeds in decoding one of the PDCCH candidates in the search space, the UE determines that the PDCCH is detected in the corresponding PDCCH candidate, and performs PDSCH reception or PUSCH transmission based on the DCI in the detected PDCCH. The PDCCH may be used to schedule DL transmissions on PDSCH and UL transmissions on PUSCH. Here, the DCI on the PDCCH is a downlink assignment (i.e., downlink grant; DL grant) including at least modulation and coding format and resource allocation information related to the downlink shared channel, or uplink It includes an uplink grant (UL grant) including a modulation and coding format and resource allocation information related to a shared channel.

Referring to FIG. 2 , an initial access (IA) procedure in a 5G communication system will be additionally described.

The UE may perform cell search, system information acquisition, beam alignment for initial access, DL measurement, and the like based on the SSB. The SSB is mixed with an SS/PBCH (Synchronization Signal/Physical Broadcast channel) block.

SSB consists of PSS, SSS and PBCH. The SSB is configured in four consecutive OFDM symbols, and PSS, PBCH, SSS/PBCH or PBCH are transmitted for each OFDM symbol. PSS and SSS consist of 1 OFDM symbol and 127 subcarriers, respectively, and PBCH consists of 3 OFDM symbols and 576 subcarriers.

Cell discovery refers to a process in which the UE acquires time/frequency synchronization of a cell, and detects a cell ID (Identifier) (eg, Physical layer Cell ID, PCI) of the cell. PSS is used to detect a cell ID within a cell ID group, and SSS is used to detect a cell ID group. PBCH is used for SSB (time) index detection and half-frame detection.

There are 336 cell ID groups, and there are 3 cell IDs for each cell ID group. There are a total of 1008 cell IDs. Information on the cell ID group to which the cell ID of the cell belongs is provided/obtained through the SSS of the cell, and information on the cell ID among 336 cells in the cell ID is provided/obtained through the PSS

The SSB is transmitted periodically according to the SSB period (periodicity). The SSB basic period assumed by the UE during initial cell discovery is defined as 20 ms. After cell access, the SSB period may be set to one of {5ms, 10ms, 20ms, 40ms, 80ms, 160ms} by the network (eg, BS).

A set of SSB bursts is formed at the beginning of the SSB period (see FIG. 4). The SSB burst set consists of a 5 ms time window (ie, half-frame), and the SSB can be transmitted up to L times within the SS burst set. The maximum number of transmissions L of the SSB can be given as follows according to the frequency band of the carrier. One slot includes up to two SSBs.

- For frequency range up to 3 GHz, L = 4

- For frequency range from 3GHz to 6GHz, L = 8

- For frequency range from 6 GHz to 52.6 GHz, L = 64

The temporal position of the SSB candidate within the SS burst set may be defined according to the subcarrier interval. The temporal positions of SSB candidates are indexed from 0 to L-1 (SSB index) in temporal order within the SSB burst set (ie, half-frame).

Multiple SSBs may be transmitted within a frequency span of a carrier wave. Physical layer cell identifiers of these SSBs need not be unique, and different SSBs may have different physical layer cell identifiers.

The UE may acquire DL synchronization by detecting the SSB. The UE may identify the structure of the SSB burst set based on the detected SSB (time) index, and may detect the symbol/slot/half-frame boundary accordingly. The frame/half-frame number to which the detected SSB belongs may be identified using system frame number (SFN) information and half-frame indication information.

Specifically, the UE may obtain a 10-bit SFN for a frame to which the PBCH belongs from the PBCH. Next, the UE may obtain 1-bit half-frame indication information. For example, when the UE detects a PBCH in which the half-frame indication bit is set to 0, it may determine that the SSB to which the PBCH belongs belongs to the first half-frame in the frame, and the half-frame indication bit is 1 When the PBCH set to ' is detected, it can be determined that the SSB to which the PBCH belongs belongs to the second half-frame in the frame. Finally, the UE may obtain the SSB index of the SSB to which the PBCH belongs based on the DMRS sequence and the PBCH payload carried by the PBCH.

Next, the acquisition of system information (SI) will be described.

The SI is divided into a master information block (MIB) and a plurality of system information blocks (SIB). SI other than MIB may be referred to as Remaining Minimum System Information (RMSI). The MIB includes information/parameters for monitoring the PDCCH scheduling the PDSCH carrying the System Information Block1 (SIB1) and is transmitted by the BS through the PBCH of the SSB. SIB1 includes information related to availability and scheduling (eg, transmission period, SI-window size) of the remaining SIBs (hereinafter, SIBx, where x is an integer of 2 or more). SIBx is included in the SI message and transmitted through the PDSCH. Each SI message is transmitted within a periodically occurring time window (ie, an SI-window).

Referring to FIG. 2 , a random access (RA) process in a 5G communication system will be additionally described.

The random access process is used for a variety of purposes. For example, the random access procedure may be used for network initial access, handover, and UE-triggered UL data transmission. The UE may acquire UL synchronization and UL transmission resources through a random access procedure. The random access process is divided into a contention-based random access process and a contention free random access process. The detailed procedure for the contention-based random access process is as follows.

The UE may transmit the random access preamble through the PRACH as Msg1 of the random access procedure in the UL. Random access preamble sequences having two different lengths are supported. The long sequence length 839 applies for subcarrier spacings of 1.25 and 5 kHz, and the short sequence length 139 applies for subcarrier spacings of 15, 30, 60 and 120 kHz.

When the BS receives the random access preamble from the UE, the BS sends a random access response (RAR) message (Msg2) to the UE. The PDCCH scheduling the PDSCH carrying the RAR is CRC-masked and transmitted with a random access (RA) radio network temporary identifier (RNTI) (RA-RNTI). The UE detecting the PDCCH masked by the RA-RNTI may receive the RAR from the PDSCH scheduled by the DCI carried by the PDCCH. The UE checks whether the random access response information for the preamble it has transmitted, that is, Msg1, is in the RAR. Whether or not random access information for Msg1 transmitted by itself exists may be determined by whether a random access preamble ID for the preamble transmitted by the UE exists. If there is no response to Msg1, the UE may retransmit the RACH preamble within a predetermined number of times while performing power ramping. The UE calculates the PRACH transmit power for the retransmission of the preamble based on the most recent path loss and power ramping counter.

The UE may transmit UL transmission on the uplink shared channel as Msg3 of the random access procedure based on the random access response information. Msg3 may include the RRC connection request and UE identifier. As a response to Msg3, the network may send Msg4, which may be treated as a contention resolution message on DL. By receiving Msg4, the UE can enter the RRC connected state.

C. Beam Management (BM) Procedure of 5G Communication System

The BM process may be divided into (1) a DL BM process using SSB or CSI-RS, and (2) a UL BM process using a sounding reference signal (SRS). In addition, each BM process may include Tx beam sweeping to determine a Tx beam and Rx beam sweeping to determine an Rx beam.

Let's look at the DL BM process using SSB.

A configuration for a beam report using the SSB is performed during channel state information (CSI)/beam configuration in RRC_CONNECTED.

- The UE receives from the BS a CSI-ResourceConfig IE including a CSI-SSB-ResourceSetList for SSB resources used for BM. The RRC parameter csi-SSB-ResourceSetList indicates a list of SSB resources used for beam management and reporting in one resource set. Here, the SSB resource set may be set to {SSBx1, SSBx2, SSBx3, SSBx4, }. The SSB index may be defined from 0 to 63.

- UE receives signals on SSB resources from the BS based on the CSI-SSB-ResourceSetList.

- When the CSI-RS reportConfig related to reporting on SSBRI and reference signal received power (RSRP) is configured, the UE reports the best SSBRI and RSRP corresponding thereto to the BS. For example, when the reportQuantity of the CSI-RS reportConfig IE is set to 'ssb-Index-RSRP', the UE reports the best SSBRI and the corresponding RSRP to the BS.

If the CSI-RS resource is configured in the same OFDM symbol(s) as the SSB, and 'QCL-TypeD' is applicable, the UE has the CSI-RS and the SSB similarly located in the 'QCL-TypeD' point of view ( quasi co-located, QCL). Here, QCL-TypeD may mean QCL between antenna ports in terms of spatial Rx parameters. When the UE receives signals of a plurality of DL antenna ports in a QCL-TypeD relationship, the same reception beam may be applied.

Next, a DL BM process using CSI-RS will be described.

The Rx beam determination (or refinement) process of the UE using the CSI-RS and the Tx beam sweeping process of the BS will be described in turn. In the UE Rx beam determination process, the repetition parameter is set to 'ON', and in the BS Tx beam sweeping process, the repetition parameter is set to 'OFF'.

First, a process of determining the Rx beam of the UE will be described.

- The UE receives the NZP CSI-RS resource set IE including the RRC parameter for 'repetition' from the BS through RRC signaling. Here, the RRC parameter 'repetition' is set to 'ON'.

- The UE repeats signals on the resource(s) in the CSI-RS resource set in which the RRC parameter 'repetition' is set to 'ON' in different OFDM symbols through the same Tx beam (or DL spatial domain transmission filter) of the BS receive

- The UE determines its own Rx beam.

- The UE omits CSI reporting. That is, the UE may omit the CSI report when the multi-RRC parameter 'repetition' is set to 'ON'.

Next, the Tx beam determination process of the BS will be described.

- The UE receives the NZP CSI-RS resource set IE including the RRC parameter for 'repetition' from the BS through RRC signaling. Here, the RRC parameter 'repetition' is set to 'OFF' and is related to the Tx beam sweeping process of the BS.

- The UE receives signals on resources in the CSI-RS resource set in which the RRC parameter 'repetition' is set to 'OFF' through different Tx beams (DL spatial domain transmission filter) of the BS.

- The UE selects (or determines) the best beam.

- The UE reports the ID (eg, CRI) and related quality information (eg, RSRP) for the selected beam to the BS. That is, when the CSI-RS is transmitted for the BM, the UE reports the CRI and the RSRP to the BS.

Next, a UL BM process using SRS will be described.

- The UE receives the RRC signaling (eg, SRS-Config IE) including the (RRC parameter) usage parameter set to 'beam management' from the BS. SRS-Config IE is used for SRS transmission configuration. The SRS-Config IE includes a list of SRS-Resources and a list of SRS-ResourceSets. Each SRS resource set means a set of SRS-resources.

- The UE determines Tx beamforming for the SRS resource to be transmitted based on the SRS-SpatialRelation Info included in the SRS-Config IE. Here, the SRS-SpatialRelation Info is set for each SRS resource and indicates whether to apply the same beamforming as that used in SSB, CSI-RS, or SRS for each SRS resource.

- If SRS-SpatialRelationInfo is configured in the SRS resource, the same beamforming as that used in SSB, CSI-RS or SRS is applied and transmitted. However, if SRS-SpatialRelationInfo is not configured in the SRS resource, the UE arbitrarily determines Tx beamforming and transmits the SRS through the determined Tx beamforming.

Next, a beam failure recovery (BFR) process will be described.

In a beamformed system, Radio Link Failure (RLF) may frequently occur due to rotation, movement, or beamforming blockage of the UE. Therefore, BFR is supported in NR to prevent frequent RLF from occurring. BFR is similar to the radio link failure recovery process, and can be supported when the UE knows new candidate beam(s). For beam failure detection, the BS sets beam failure detection reference signals to the UE, and the UE determines that the number of beam failure indications from the physical layer of the UE is within a period set by the RRC signaling of the BS. When a threshold set by RRC signaling is reached (reach), a beam failure is declared (declare). after beam failure is detected, the UE triggers beam failure recovery by initiating a random access procedure on the PCell; Beam failure recovery is performed by selecting a suitable beam (if the BS provides dedicated random access resources for certain beams, these are prioritized by the UE). Upon completion of the random access procedure, it is considered that beam failure recovery has been completed.

D. URLLC (Ultra-Reliable and Low Latency Communication)

URLLC transmission defined in NR is (1) a relatively low traffic size, (2) a relatively low arrival rate (low arrival rate), (3) extremely low latency requirements (eg, 0.5, 1ms), (4) a relatively short transmission duration (eg, 2 OFDM symbols), and (5) transmission for an urgent service/message. In the case of UL, transmission for a specific type of traffic (eg, URLLC) is multiplexed with other previously scheduled transmission (eg, eMBB) in order to satisfy a more stringent latency requirement. Needs to be. In this regard, as one method, information to be preempted for a specific resource is given to the previously scheduled UE, and the resource is used by the URLLC UE for UL transmission.

For NR, dynamic resource sharing between eMBB and URLLC is supported. eMBB and URLLC services may be scheduled on non-overlapping time/frequency resources, and URLLC transmission may occur on resources scheduled for ongoing eMBB traffic. The eMBB UE may not know whether the PDSCH transmission of the corresponding UE is partially punctured, and the UE may not be able to decode the PDSCH due to corrupted coded bits. In consideration of this, NR provides a preemption indication. The preemption indication may be referred to as an interrupted transmission indication.

With respect to the preemption indication, the UE receives the DownlinkPreemption IE through RRC signaling from the BS. When the UE is provided with the DownlinkPreemption IE, for monitoring the PDCCH carrying DCI format 2_1, the UE is configured with the INT-RNTI provided by the parameter int-RNTI in the DownlinkPreemption IE. The UE is additionally configured with a set of serving cells by INT-ConfigurationPerServing Cell including a set of serving cell indices provided by servingCellID and a corresponding set of positions for fields in DCI format 2_1 by positionInDCI, dci-PayloadSize It is established with the information payload size for DCI format 2_1 by , and is set with the indicated granularity of time-frequency resources by timeFrequencySect.

The UE receives DCI format 2_1 from the BS based on the DownlinkPreemption IE.

When the UE detects the DCI format 2_1 for the serving cell in the configured set of serving cells, the UE determines that the DCI format of the set of PRBs and the set of symbols of the monitoring period immediately preceding the monitoring period to which the DCI format 2_1 belongs. It can be assumed that there is no transmission to the UE in the PRBs and symbols indicated by 2_1. For example, the UE sees that the signal in the time-frequency resource indicated by the preemption is not the scheduled DL transmission for itself and decodes data based on the signals received in the remaining resource region.

E. mMTC (massive MTC)

mMTC (massive machine type communication) is one of the scenarios of 5G to support hyper-connectivity service that communicates simultaneously with a large number of UEs. In this environment, the UE communicates intermittently with a very low transmission rate and mobility. Therefore, mMTC is primarily aimed at how long the UE can run at a low cost. In relation to mMTC technology, 3GPP deals with MTC and NB (NarrowBand)-IoT.

The mMTC technology has features such as repeated transmission of PDCCH, PUCCH, physical downlink shared channel (PDSCH), PUSCH, and the like, frequency hopping, retuning, and guard period.

That is, a PUSCH (or PUCCH (particularly, long PUCCH) or PRACH) including specific information and a PDSCH (or PDCCH) including a response to specific information are repeatedly transmitted. Repeated transmission is performed through frequency hopping, and for repeated transmission, (RF) retuning is performed in a guard period from a first frequency resource to a second frequency resource, and specific information And a response to specific information may be transmitted/received through a narrowband (ex. 6 RB (resource block) or 1 RB).

F. Basic AI operation using 5G communication

3 shows an example of basic operations of a user terminal and a 5G network in a 5G communication system.

The UE transmits the specific information transmission to the 5G network (S1). The 5G network performs 5G processing on the specific information (S2). Here, the 5G processing may include AI processing. Then, the 5G network transmits a response including the AI processing result to the UE (S3).

G. Application operation between user terminal and 5G network in 5G communication system

Hereinafter, the AI operation using 5G communication will be described in more detail with reference to FIGS. 1 and 2 and salpin wireless communication technology (BM procedure, URLLC, Mmtc, etc.).

First, the method proposed in this specification, which will be described later, and the basic procedure of the application operation to which the eMBB technology of 5G communication is applied will be described.

As in step S1 and step S3 of FIG. 3, in order for the UE to transmit/receive signals, information, etc. with the 5G network, the UE has an initial access procedure and random access with the 5G network before step S1 of FIG. random access) procedure.

More specifically, the UE performs an initial connection procedure with the 5G network based on the SSB to obtain DL synchronization and system information. A beam management (BM) process and a beam failure recovery process may be added to the initial access procedure, and in the process of the UE receiving a signal from the 5G network, a QCL (quasi-co location) relationship can be added.

In addition, the UE performs a random access procedure with the 5G network for UL synchronization acquisition and/or UL transmission. In addition, the 5G network may transmit a UL grant for scheduling transmission of specific information to the UE. Accordingly, the UE transmits specific information to the 5G network based on the UL grant. In addition, the 5G network transmits a DL grant for scheduling transmission of a 5G processing result for the specific information to the UE. Accordingly, the 5G network may transmit a response including the AI processing result to the UE based on the DL grant.

Next, the method proposed in the present specification, which will be described later, and the basic procedure of the application operation to which the URLLC technology of 5G communication is applied will be described.

As described above, after the UE performs an initial access procedure and/or a random access procedure with the 5G network, the UE may receive a DownlinkPreemption IE from the 5G network. Then, the UE receives DCI format 2_1 including a pre-emption indication from the 5G network based on the DownlinkPreemption IE. And, the UE does not perform (or expect or assume) the reception of eMBB data in the resource (PRB and/or OFDM symbol) indicated by the pre-emption indication. Thereafter, the UE may receive a UL grant from the 5G network when it is necessary to transmit specific information.

Next, the method proposed in the present specification, which will be described later, and the basic procedure of the application operation to which the mMTC technology of 5G communication is applied will be described.

Among the steps of FIG. 3, the parts that are changed by the application of the mMTC technology will be mainly described.

In step S1 of FIG. 3 , the UE receives a UL grant from the 5G network to transmit specific information to the 5G network. Here, the UL grant includes information on the number of repetitions for the transmission of the specific information, and the specific information may be repeatedly transmitted based on the information on the number of repetitions. That is, the UE transmits specific information to the 5G network based on the UL grant. In addition, repeated transmission of specific information may be performed through frequency hopping, transmission of the first specific information may be transmitted in a first frequency resource, and transmission of the second specific information may be transmitted in a second frequency resource. The specific information may be transmitted through a narrowband of 6RB (Resource Block) or 1RB (Resource Block).

The above salpin 5G communication technology may be applied in combination with the methods proposed in the present specification to be described later, or may be supplemented to specify or clarify the technical characteristics of the methods proposed in the present specification.

H. Beam Management (BM)

The BM process is a set of BS (or transmission and reception point (TRP)) and/or UE beams that can be used for downlink (DL) and uplink (UL) transmission/reception ) as processes for acquiring and maintaining, may include the following processes and terms.

- Beam measurement (beam measurement): an operation in which the BS or UE measures the characteristics of the received beamforming signal.

- Beam determination (beam determination): the operation of the BS or UE to select its own transmission beam (Tx beam) / reception beam (Rx beam).

- Beam sweeping: An operation of covering a spatial domain using a transmit and/or receive beam for a predetermined time interval in a predetermined manner.

- Beam report: an operation in which the UE reports information of a beamformed signal based on beam measurement.

The BM process may be divided into (1) a DL BM process using SSB or CSI-RS, and (2) a UL BM process using a sounding reference signal (SRS). In addition, each BM process may include Tx beam sweeping to determine a Tx beam and Rx beam sweeping to determine an Rx beam.

DL BM Course

The DL BM process may include (1) transmission of beamformed DL RSs (eg, CSI-RS or SSB) by the BS, and (2) beam reporting by the UE.

Here, the beam report may include preferred DL RS ID(s) and reference signal received power (RSRP) corresponding thereto. The DL RS ID may be an SSB Resource Indicator (SSBRI) or a CSI-RS Resource Indicator (CRI).

5 shows an example of beamforming using SSB and CSI-RS.

5 , an SSB beam and a CSI-RS beam may be used for beam measurement. The measurement metric is RSRP for each resource/block. SSB may be used for coarse beam measurement, and CSI-RS may be used for fine beam measurement. SSB can be used for both Tx beam sweeping and Rx beam sweeping. Rx beam sweeping using SSB may be performed by attempting to receive the SSB while the UE changes the Rx beam for the same SSBRI across multiple SSB bursts. Here, one SS burst includes one or more SSBs, and one SS burst set includes one or more SSB bursts.

DL BM using SSB

6 is a flowchart illustrating an example of a DL BM process using SSB.

A configuration for a beam report using the SSB is performed during channel state information (CSI)/beam configuration in RRC_CONNECTED.

- The UE receives a CSI-ResourceConfig IE including a CSI-SSB-ResourceSetList for SSB resources used for BM from the BS (S410). The RRC parameter csi-SSB-ResourceSetList indicates a list of SSB resources used for beam management and reporting in one resource set. Here, the SSB resource set is {SSBx1, SSBx2, SSBx3, SSBx4, ... } can be set. The SSB index may be defined from 0 to 63.

- The UE receives signals on SSB resources from the BS based on the CSI-SSB-ResourceSetList (S420).

- When the CSI-RS reportConfig related to reporting on SSBRI and reference signal received power (RSRP) is configured, the UE reports the best SSBRI and RSRP corresponding thereto to the BS (S430). For example, when the reportQuantity of the CSI-RS reportConfig IE is set to 'ssb-Index-RSRP', the UE reports the best SSBRI and the corresponding RSRP to the BS.

If the CSI-RS resource is configured in the same OFDM symbol(s) as the SSB, and 'QCL-TypeD' is applicable, the UE has the CSI-RS and the SSB similarly located in the 'QCL-TypeD' point of view ( quasi co-located, QCL). Here, QCL-TypeD may mean QCL between antenna ports in terms of spatial Rx parameters. When the UE receives signals of a plurality of DL antenna ports in a QCL-TypeD relationship, the same reception beam may be applied. For details on QCL, see Section 4. QCL below.

DL BM using CSI-RS

Looking at the CSI-RS use, i) When a repetition parameter is set for a specific CSI-RS resource set and TRS_info is not set, the CSI-RS is used for beam management. ii) When the repetition parameter is not set and TRS_info is set, the CSI-RS is used for a tracking reference signal (TRS). iii) If the repetition parameter is not set and TRS_info is not set, the CSI-RS is used for CSI acquisition.

(RRC parameter) When repetition is set to 'ON', it is related to the UE's Rx beam sweeping process. When repetition is set to 'ON', when the UE receives the NZP-CSI-RS-ResourceSet set, the UE sends signals of at least one CSI-RS resource in the NZP-CSI-RS-ResourceSet to the same downlink spatial domain filter. can be assumed to be transmitted. That is, at least one CSI-RS resource in the NZP-CSI-RS-ResourceSet is transmitted through the same Tx beam. Here, signals of at least one CSI-RS resource in the NZP-CSI-RS-ResourceSet may be transmitted in different OFDM symbols.

On the other hand, when the repetition is set to 'OFF', it is related to the Tx beam sweeping process of the BS. If repetition is set to 'OFF', the UE does not assume that signals of at least one CSI-RS resource in the NZP-CSI-RS-ResourceSet are transmitted through the same downlink spatial domain transmission filter. That is, signals of at least one CSI-RS resource in the NZP-CSI-RS-ResourceSet are transmitted through different Tx beams. 7 shows another example of a DL BM process using CSI-RS.

FIG. 7(a) shows the Rx beam determination (or refinement) process of the UE, and FIG. 7(b) shows the Tx beam sweeping process of the BS. In addition, FIG. 7(a) is a case in which the repetition parameter is set to 'ON', and FIG. 7(b) is a case in which the repetition parameter is set to 'OFF'.

With reference to FIGS. 7A and 8 , a process of determining the Rx beam of the UE will be described.

8 is a flowchart illustrating an example of a process of determining a reception beam of a UE.

- The UE receives the NZP CSI-RS resource set IE including the RRC parameter for 'repetition' from the BS through RRC signaling (S610). Here, the RRC parameter 'repetition' is set to 'ON'.

- The UE repeats signals on the resource(s) in the CSI-RS resource set in which the RRC parameter 'repetition' is set to 'ON' in different OFDM symbols through the same Tx beam (or DL spatial domain transmission filter) of the BS Receive (S620).

- The UE determines its own Rx beam (S630).

- The UE omits the CSI report (S640). That is, the UE may omit the CSI report when the multi-RRC parameter 'repetition' is set to 'ON'.

With reference to FIGS. 7(b) and 9, the Tx beam determination process of the BS will be described.

9 is a flowchart illustrating an example of a transmission beam determination process of the BS.

- The UE receives the NZP CSI-RS resource set IE including the RRC parameter for 'repetition' from the BS through RRC signaling (S710). Here, the RRC parameter 'repetition' is set to 'OFF' and is related to the Tx beam sweeping process of the BS.

- The UE receives signals on resources in the CSI-RS resource set in which the RRC parameter 'repetition' is set to 'OFF' through different Tx beams (DL spatial domain transmission filter) of the BS (S720).

- The UE selects (or determines) the best (best) beam (S730)

- The UE reports the ID (eg, CRI) and related quality information (eg, RSRP) for the selected beam to the BS (S740). That is, when the CSI-RS is transmitted for the BM, the UE reports the CRI and the RSRP to the BS.

FIG. 10 shows an example of resource allocation in time and frequency domains related to the operation of FIG. 7 .

When repetition 'ON' is set in the CSI-RS resource set, a plurality of CSI-RS resources are repeatedly used by applying the same transmission beam, and when repetition 'OFF' is set in the CSI-RS resource set, different CSI-RS Resources may be transmitted in different transmission beams.

DL BM-related beam indication (beam indication)

The UE may receive a list of at least M candidate Transmission Configuration Indication (TCI) states for at least Quasi Co-location (QCL) indication through RRC signaling. Here, M depends on the UE capability, and may be 64.

Each TCI state may be set with one reference signal (RS) set. Table 1 shows an example of TCI-State IE. TCI-State IE is associated with one or two DL reference signal (RS) corresponding quasi co-location (QCL) type.

-- ASN1START-- TAG-TCI-STATE-STARTTCI-State ::= SEQUENCE { tci-StateId TCI-StateId, qcl-Type1 QCL-Info, qcl-Type2 QCL-Info OPTIONAL, -- Need R ...}QCL -Info ::= SEQUENCE { cell ServCellIndex OPTIONAL, -- Need R bwp-Id BWP-Id OPTIONAL, -- Cond CSI-RS-Indicated referenceSignal CHOICE { csi-rs NZP-CSI-RS-ResourceId, ssb SSB-Index } , qcl-Type ENUMERATED {typeA, typeB, typeC, typeD}, ...}-- TAG-TCI-STATE-STOP-- ASN1STOP

In Table 1, 'bwp-Id' indicates the DL BWP where the RS is located, 'cell' indicates the carrier where the RS is located, and 'referencesignal' is the source of the similar co-location for the target antenna port(s) ( source) or a reference signal including the reference antenna port(s). The target antenna port(s) may be CSI-RS, PDCCH DMRS, or PDSCH DMRS.

Quasi-Co Location (QCL)

The UE may receive a list containing up to M TCI-state settings to decode the PDSCH according to the detected PDCCH with DCI intended for the UE and a given given cell. Here, M depends on the UE capability.

As illustrated in Table 1, each TCI-State includes parameters for establishing a QCL relationship between one or two DL RSs and a DM-RS port of a PDSCH. The QCL relationship is established with the RRC parameter qcl-Type1 for the first DL RS and qcl-Type2 (if configured) for the second DL RS.

The QCL type corresponding to each DL RS is given by the parameter 'qcl-Type' in QCL-Info, and may take one of the following values:

- 'QCL-TypeA': {Doppler shift, Doppler spread, average delay, delay spread}

- 'QCL-TypeB': {Doppler shift, Doppler spread}

- 'QCL-TypeC': {Doppler shift, average delay}

- 'QCL-TypeD': {Spatial Rx parameter}

For example, if the target antenna port is a specific NZP CSI-RS, the corresponding NZP CSI-RS antenna ports are indicated/configured to be QCL with a specific TRS from a QCL-Type A perspective and a specific SSB from a QCL-Type D perspective. have. Upon receiving this instruction/configuration, the UE receives the corresponding NZP CSI-RS using the Doppler and delay values measured in QCL-TypeA TRS, and applies the reception beam used for QCL-TypeD SSB reception to the corresponding NZP CSI-RS reception. can do.

UL BM course

In the UL BM, beam reciprocity (or beam correspondence) between Tx beams and Rx beams may or may not be established according to UE implementation. If the correlation between the Tx beam and the Rx beam is established in both the BS and the UE, the UL beam pair may be aligned through the DL beam pair. However, when the correlation between the Tx beam and the Rx beam is not established in either of the BS and the UE, a UL beam pair determination process is required separately from the DL beam pair determination.

In addition, even when both the BS and the UE maintain beam correspondence, the BS may use the UL BM procedure for DL Tx beam determination without the UE requesting a report of a preferred beam.

UL BM may be performed through beamformed UL SRS transmission, and whether the UL BM of the SRS resource set is applied is set by an RRC parameter in (RRC parameter) usage. If the purpose is set to 'BeamManagement (BM)', only one SRS resource may be transmitted to each of a plurality of SRS resource sets at a given time instant.

The UE may receive one or more sounding reference signal (SRS) resource sets configured by (RRC parameter) SRS-ResourceSet (through RRC signaling, etc.). For each SRS resource set, the UE may be configured with K≧1 SRS resources. Here, K is a natural number, and the maximum value of K is indicated by SRS_capability.

Like DL BM, the UL BM process may be divided into Tx beam sweeping of the UE and Rx beam sweeping of BS.

11 shows an example of a UL BM process using SRS.

Figure 11 (a) shows the Rx beamforming determination process of the BS, Figure 11 (b) shows the Tx beam sweeping process of the UE.

12 is a flowchart illustrating an example of a UL BM process using SRS.

- The UE receives the RRC signaling (eg, SRS-Config IE) including the (RRC parameter) usage parameter set to 'beam management' from the BS (S1010). SRS-Config IE is used for SRS transmission configuration. The SRS-Config IE includes a list of SRS-Resources and a list of SRS-ResourceSets. Each SRS resource set means a set of SRS-resources.

- The UE determines Tx beamforming for the SRS resource to be transmitted based on the SRS-SpatialRelation Info included in the SRS-Config IE (S1020). Here, the SRS-SpatialRelation Info is set for each SRS resource and indicates whether to apply the same beamforming as that used in SSB, CSI-RS, or SRS for each SRS resource.

- If SRS-SpatialRelationInfo is configured in the SRS resource, the same beamforming as that used in SSB, CSI-RS or SRS is applied and transmitted. However, if SRS-SpatialRelationInfo is not configured in the SRS resource, the UE arbitrarily determines Tx beamforming and transmits the SRS through the determined Tx beamforming (S1030).

More specifically, for P-SRS with 'SRS-ResourceConfigType' set to 'periodic':

i) When SRS-SpatialRelationInfo is set to 'SSB/PBCH', the UE applies the same spatial domain transmission filter as the spatial domain Rx filter used for reception of the SSB/PBCH (or generated from the filter) to obtain the corresponding SRS. send; or

ii) when SRS-SpatialRelationInfo is set to 'CSI-RS', the UE transmits the SRS by applying the same spatial domain transmission filter used for reception of the CSI-RS; or

iii) When SRS-SpatialRelationInfo is set to 'SRS', the UE transmits the corresponding SRS by applying the same spatial domain transmission filter used for SRS transmission.

- Additionally, the UE may or may not receive feedback on the SRS from the BS as in the following three cases (S1040).

i) When Spatial_Relation_Info is configured for all SRS resources in the SRS resource set, the UE transmits the SRS in the beam indicated by the BS. For example, when Spatial_Relation_Info all indicate the same SSB, CRI, or SRI, the UE repeatedly transmits the SRS on the same beam.

ii) Spatial_Relation_Info may not be set for all SRS resources in the SRS resource set. In this case, the UE can freely transmit while changing SRS beamforming.

iii) Spatial_Relation_Info may be configured only for some SRS resources in the SRS resource set. In this case, for the configured SRS resource, the SRS is transmitted with the indicated beam, and for the SRS resource for which Spatial_Relation_Info is not configured, the UE can arbitrarily apply Tx beamforming to transmit.

Beam failure recovery (BFR) process

In a beamformed system, Radio Link Failure (RLF) may frequently occur due to rotation, movement, or beamforming blockage of the UE. Therefore, BFR is supported in NR to prevent frequent RLF from occurring. BFR is similar to the radio link failure recovery process, and can be supported when the UE knows new candidate beam(s).

For beam failure detection, the BS sets beam failure detection reference signals to the UE, and the UE determines that the number of beam failure indications from the physical layer of the UE is within a period set by the RRC signaling of the BS. When a threshold set by RRC signaling is reached (reach), a beam failure is declared (declare).

after beam failure is detected, the UE triggers beam failure recovery by initiating a random access procedure on the PCell; Beam failure recovery is performed by selecting a suitable beam (if the BS provides dedicated random access resources for certain beams, these are prioritized by the UE). Upon completion of the random access procedure, it is considered that beam failure recovery has been completed.

J. Main embodiment(s) of this specification

The above salpin 5G communication technology may be applied in combination with the methods proposed in the present specification to be described later, or may be supplemented to specify or clarify the technical characteristics of the methods proposed in the present specification. On the other hand, the communication method using the LIS proposed in the present specification may be applied in combination with a communication service by 3G, 4G and/or 6G communication technology as well as the 5G communication technology described above.

In addition, the above salpin beam management technology can be applied in combination with the methods proposed in the present specification to be described later. Here, among the contents described in relation to beam management, the function and/or operation of the base station (BS) may be performed by the transmitting terminal (Tx UE), the transmitting vehicle, or the autonomous driving vehicle. Here, among the contents described in relation to beam management, the function and/or operation of the UE may be performed by the receiving terminal (Rx UE), the receiving vehicle, or the target vehicle, but is not limited thereto.

J.1. Beam management using LIS (Large Intelligent Surface)

A wireless communication system according to an embodiment of the present specification includes a reflection module. Here, the reflection module may be a large inetelligent surface (LIS).

The LIS is a kind of reflector implemented as a meta-plane, and can adjust the reflection pattern of the incident electromagnetic wave to a desired shape. For example, the LIS can variably adjust the phase of electromagnetic waves in units of atoms constituting the meta-plane, thereby providing a variable reflection pattern in response to a change in the channel environment.

In this way, the LIS can obtain the same effect as the beamforming of the antenna array by adjusting the reflection pattern of the electromagnetic wave in a desired direction. In addition, since the LIS is composed of a passive element, power consumption is low in operation, and the cost is lower than that of a conventional small cell or distributed antenna system (DAS), resulting in low operating expenditure (OPEX). /CAPEX (capital expenditure) can be used to provide communication services in shadowed areas.

13 is a diagram for explaining an LIS applied to a wireless communication system according to an embodiment of the present specification.

13A illustrates an example of a reflection module (eg, LIS). The LIS may include a plurality of meta-atoms. A meta-atom is typically composed of a conductive material (eg copper, silver, gold, etc.) and is placed on a dielectric substrate. Initially, copper and silicon were used, but various options such as graphene are being studied. In one example, the meta atom represents a periodically repeating metal pattern on a silicon substrate.

In addition, the meta atom can be implemented in various patterns. For example, the meta atom may be implemented as a split-ring resonator, but is not limited thereto.

In addition, the meta atom may be divided into a dynamic meta atom or a static meta atom. The dynamic meta atom may include component(s) for changing the phase, such as a micro switch or a CMOS transistor, which generally changes a local impedance through an external control signal. In the case of a static meta-atom, the interaction with the colliding electromagnetic wave is fixed, whereas in the case of a dynamic meta-atom, a time-variant controlled response is allowed.

Referring to FIG. 13B , it can be confirmed that the LIS in which a plurality of meta-atoms are disposed implements the beamforming effect of the array antenna.

Hereinafter, it is assumed that the 'reflection module' in the specification is the 'LIS' described above.

14 is a conceptual diagram of a beam management method using a reflection module.

Referring to FIG. 14 , a wireless communication system using a reflection module includes a base station, a terminal, and a reflection module. In an environment where obstacles exist, it can be assumed that the Below 6GHz (B6G) coverage can cover terminals and reflective modules, but the Above 6GHz (A6G) coverage is divided into shaded areas due to obstacles.

For example, when an obstacle exists between the base station and the terminal, a none line of sight (NLOS) occurs due to the obstacle. As a result, the signal for communication is not smoothly transmitted to the area covered by the obstacle, and in particular, high frequency (eg, A6G, THz) is more difficult to be transmitted to the terminal. Accordingly, a shadow area associated with A6G occurs, and in order to solve the problem, the wireless communication system according to an embodiment of the present specification uses a reflection module.

The reflection module may perform a function of a reflection plate for transmitting a high-frequency signal having strong straightness and a large path loss. In particular, the reflection module may provide a beamforming effect by adjusting a reflection pattern beyond the function of a simple reflection plate as described above.

15 is a flowchart of a beam management method according to an embodiment of the present specification.

The beam search may be divided into an initial beam establishment process for setting an initial beam and a beam adjustment process for tracking a beam according to the location of the terminal and narrowing the shape of the beam. Meanwhile, the beam search process according to various embodiments further includes a reflection pattern searching process as well as the aforementioned initial beam search process and beam tracking process. The reflection pattern search process refers to a process of finding a reflection pattern of the reflection module for providing a line-of-sight (LOS) between the base station and the terminal. The procedure for finding the reflection pattern can also be applied to the same procedure as the beam search process of the array antenna. Hereinafter, the process of simultaneously searching the beam pattern of the base station and the reflection pattern of the reflection module will be described. For reference, the synchronization signal and the synchronization signal or SSB may be used interchangeably.

- Beam search may be performed at regular intervals (S110).

In one embodiment, the BS transmits a synchronization signal for downlink synchronization during the first period. As an example, the synchronization signal may be transmitted through broadcast. When the first period ends, the BS transmits a request for changing the reflection pattern of the reflection module spaced apart from the BS during the second period and transmits a synchronization signal upon receiving a response to the request.

Here, the request may be transmitted through a control link provided separately between the BS and the reflection module. In addition, the request includes a reflection pattern index, and the reflection pattern of the reflection module is set to correspond to the reflection pattern index. For example, the reflection pattern index may include a broad beam index for providing a broad beam, and one or more narrow beam indexes for providing a narrow beam in a specific direction. Here, the reflection pattern index may be used interchangeably with the LIS Beam Index (refer to FIGS. 18, 20, and 21).

Here, the broadbeam index may be one type, but the narrow beam index may include at least one according to the direction of each narrow beam. For example, there may be narrow beam indices of LISBeamIndex0, LISBeamIndex1, LISBeamIndex2, ..., LISBeamIndexK to respectively correspond to K+1 directions (K is a positive integer). The broad beam index is mainly used in initial beam configuration, and the narrow beam index is mainly used in beam tracking, which will be described later.

When the BS receives a response to the request, it transmits a synchronization signal for downlink synchronization and a reflection module index through the reflection module. The reflection module index, as described above, is an index indicating a specific reflection module.

Specifically, the BS receives a response to the request from the reflection module. The above response is a report informing that the reflection pattern of the reflection module has been changed according to the request. When the BS receives a response from the reflection module indicating that the reflection pattern is adjusted to a pattern reflecting the broad beam, it may transmit at least one synchronization signal to the UE through the reflection module. For example, the BS may transmit synchronization signals of Beam#1, Beam#2, Beam#3, ..., Beam#N to the UE. All of the synchronization signals transmitted here may be signals of A6G (above 6GHz).

The UE receives the synchronization signals of Beam#1, Beam#2, Beam#3, ..., Beam#N in the LIS-Assisted window, and performs a random access process with the BS based on the index of the received synchronization signal. can

In this case, the UE may identify a base station transmission beam index (BS Beam Index) and a reflection module supporting assistance based on the received synchronization signal. The confirmation process of the supported reflection module will be described assuming the first to second M beam search windows.

According to the above assumption, in the first, third, fifth, ..., 2M-1 beam search windows, the BS transmits the synchronization signal regardless of the reflection module, and the second, fourth, sixth, .. ., in the 2M beam search window, the BS transmits to the UE a reflection module index indicating a reflection module that has received a request to change the reflection pattern along with the synchronization signal. For example, if a request including a broad beam index is transmitted to the first reflection module in the second beam search window, the first reflection module reports to the BS that the change of the reflection pattern has been performed. When the BS receives the report from the first reflection module, Beam#1, Beam#2, Beam#3, ..., Beam#N together with an index (eg, LIS#1) indicating the first reflection module to the UE. It is possible to transmit a synchronization signal such as As such, the UE determines whether a reflection module is involved in the process of transmitting a synchronization signal based on the reflection module index transmitted in the second, fourth, sixth, ..., 2M beam search window and which reflection module is present. You can check if you are involved.

In addition, the UE and the BS each perform a random access process in the first to second M beam search windows. Specifically, the BS performs an initial beam establishment (Beam Establishment) based on a synchronization signal with the UE. For example, the BS may perform initial downlink and uplink beam configuration through a random access process based on a synchronization signal with the UE.

At this time, the UE may generate a report on the support of the reflection module. If random access not by the reflection module is attempted at least once in the entire beam search window, the UE performs beam tracking according to the first algorithm, and when only random access by the reflection module is attempted, the UE performs beam tracking according to the second algorithm can be performed.

The UE may determine the first and second algorithms based on the reflection module index. As an example, the UE may distinguish the first and second algorithms by the presence or absence of a reflection module index.

When the UE is located in the shadow area, the synchronization signal is not transmitted to the UE in the first, third, fifth, ..., 2M-1 beam search windows among the first to second M beam search windows. As a result, the UE receives only the synchronization signal including the specific reflection module index from at least one of the second, fourth, sixth, ..., 2M beam search windows, wherein the UE receives the beam according to the second algorithm. do the tracking.

In contrast, when the UE is located in the non-shaded area, the synchronization signal is transmitted to the UE in at least one of the first, third, fifth, ..., 2M-1 beam search windows among the first to second M beam search windows. can be received for In this case, the UE performs beam tracking according to the first algorithm even if it receives a synchronization signal including a specific reflection module index in at least one of the second, fourth, sixth, ..., 2M beam search windows.

As such, since an operation for additionally controlling the reflection module is required to perform the second algorithm, the algorithm is more complicated, and thus the wireless communication system can distinguish a process in which control of the reflection module is essential.

- Referring back to FIG. 15, if there is support of the reflection module according to the report (S120: YES), the BS transmits a narrow beam index for adjusting the reflection pattern to the reflection module, and the reflection module is a narrow beam index The reflection pattern is changed to a beam pattern corresponding to (S130).

In this case, the BS transmits a signal in a direction selected based on the base station beam index of the BS determined in the initial beam search, and does not transmit the signal by sweeping in a plurality of directions as in the initial beam search process. For example, if the UE and the BS perform initial beam search by using the first reflection module, the base station beam index may be fixed to be directed to the first reflection module. In this case, the BS transmits a signal only to the first reflection module selected in the beam tracking window, and beam tracking for adjusting the shape of the beam may be performed by changing the reflection pattern of the first reflection module.

- Thereafter, the BS may receive a response guiding the change of the reflection pattern from the reflection module, or transmit a narrow beam index and transmit a reference signal to the UE after a set time has elapsed (S140).

Specifically, the BS may transmit LISBeamIndex1 to the selected reflection module so that the reflection module may change to pattern1 in response to LISBeamIndex1. Thereafter, the BS transmits a reference signal to the UE through the reflection module changed to pattern1. Here, the reference signal corresponds to LISBeamIndex1.

Then, the BS repeats the transmission of the aforementioned reference signal several times to perform an operation similar to a beam sweep by the antenna array. For example, when the transmission of the reference signal associated with LISBeamIndex1 is completed, the reflection pattern from LISBeamIndex1 to LISBeamIndexK is changed in such a way that the transmission of the reference signal associated with LISBeamIndex2 is performed, and the reference signals corresponding to each of the reflection pattern indices are transmitted to the UE. can

Meanwhile, S130 and S140 are performed in a beam tracking window, and the beam tracking window may exist differently for each UE. For example, UEs serviced by the same reflection module may be simultaneously beam tracked in one beam tracking window. For another example, UEs serviced by different reflection modules may be beam-tracked in a separate window.

In other words, the transmission of the reference signals by one reflection module may be performed in one beam tracking window. When the transmission of the reference signal by the first reflection module in the first beam tracking window is completed, the BS transmits the reference signal by the second reflection module in the second beam tracking window.

- Referring back to FIG. 15, if there is no support from the reflection module according to the report (S120: NO), different reference signals corresponding to the beam index of the synchronization signal(s) for downlink synchronization are transmitted to the UE (S150). ).

Here, the beam tracking window may exist differently for each UE, and the BS may transmit different reference signals to the UE by changing N (N is a positive integer) transmission beams in the beam search window.

16 is a flowchart of a beam management method according to an embodiment of the present specification.

- The BS transmits a first synchronization signal for downlink synchronization during the first period (S210).

Here, the synchronization signal may be transmitted through broadcast. When the UE receives the first synchronization signal from the BS, the UE may perform a random access procedure based on the index of the received first synchronization signal. However, if the UE is located in a shaded area where it is difficult to receive the first synchronization signal, the above-described random access procedure will be difficult to perform.

- When the first period ends (S220: YES), the BS transmits a request to change the reflection pattern of the reflection module located apart from the BS at the start point of the second period (S230).

Here, the request may be transmitted through a control link provided separately between the BS and the reflection module. In addition, the request includes a reflection pattern index, and the reflection pattern of the reflection module is set to correspond to the reflection pattern index. For example, the reflection pattern index may include a broad beam index for providing a broad beam, and one or more narrow beam indexes for providing a narrow beam in a specific direction. Here, the reflection pattern index may be used interchangeably with the LIS Beam Index (refer to FIGS. 18, 20, and 21).

Here, the broadbeam index may be one type, but the narrow beam index may include at least one according to the direction of each narrow beam. For example, there may be narrow beam indices of LISBeamIndex0, LISBeamIndex1, LISBeamIndex2, ..., LISBeamIndexK to respectively correspond to K+1 directions (K is a positive integer). The broad beam index is mainly used in initial beam configuration, and the narrow beam index is mainly used in beam tracking, which will be described later.

- The BS transmits a second synchronization signal and information indicating a specific reflection module to the UE when the condition set for the second period is satisfied (S240).

The second synchronization signal is transmitted in a beam search window different from the first synchronization signal. However, the second synchronization signal is composed of the same beam patterns as the first synchronization signal. For example, the first and second synchronization signals may have the same base station beam indices. For example, the first and second synchronization signals may have the same indexes of Beam#1, Beam#2, Beam#3, ..., Beam#N.

The reflection module index, as described above, is an index indicating a specific reflection module. A predetermined reflection module may be disposed on the wireless communication system. For example, when K (K is a positive integer) reflective modules installed in a room, the BS stores indexes indicating the first to Kth reflective modules in the memory. The BS transmits the reflection module index indicating the reflection module to provide identification information of the reflection module used to provide a communication service to the UE.

The set condition includes the first condition and/or the second condition. In the case of the first condition, the BS transmits a synchronization signal when the condition of receiving a response to the request to change the reflection pattern is satisfied. In the case of the second condition, the BS transmits a request to change the reflection pattern and transmits a synchronization signal when the set time elapses. The first and second conditions may be selectively applied, or may be combined into a third condition requiring both of the first and second conditions to be satisfied.

For example, in the case of the first condition, the BS receives a response to the request from the reflection module. The above response is a report informing that the reflection pattern of the reflection module has been changed according to the request. When the BS receives a response from the reflection module indicating that the reflection pattern is adjusted to a pattern reflecting the broad beam, it may transmit at least one synchronization signal to the UE through the reflection module. For example, the BS may transmit synchronization signals of Beam#1, Beam#2, Beam#3, ..., Beam#N to the UE. All of the synchronization signals transmitted here may be signals of A6G (above 6GHz).

The UE receives the synchronization signals of Beam#1, Beam#2, Beam#3, ..., Beam#N in the LIS-Assisted window, and performs a random access process with the BS based on the index of the received synchronization signal. can For reference, the LIS-Assisted window means a window in which the BS transmits information about the reflection module among the beam search windows (see FIG. 18 ).

In this case, the UE may identify a base station transmission beam index (BS Beam Index) and a reflection module supporting assistance based on the received synchronization signal.

- When the second period including the LIS-Assisted window ends, the BS increases the reflection module index by 1 and repeats the process of the first period (S260, S270: NO). However, when the reflection module index reaches the maximum value, the BS no longer returns to the first period and ends the beam search procedure (S270: YES).

Here, the maximum value of the reflection module index corresponds to the number of reflection modules installed in the wireless communication system.

In the following specification, processes S260 to S270 will be described assuming the first to second M beam search windows.

According to the above assumption, in the first, third, fifth, ..., 2M-1 beam search windows, the BS transmits the synchronization signal regardless of the reflection module, and the second, fourth, sixth, .. ., in the 2M beam search window, the BS transmits to the UE a reflection module index indicating a reflection module that has received a request to change the reflection pattern along with the synchronization signal.

In an example, if a request including a broad beam index is transmitted to the first reflection module in the second beam search window, the first reflection module reports to the BS that the change of the reflection pattern has been performed. When the BS receives the report from the first reflection module, Beam#1, Beam#2, Beam#3, ..., Beam#N together with an index (eg, LIS#1) indicating the first reflection module to the UE. It is possible to transmit a synchronization signal such as As such, the UE determines whether a reflection module is involved in the process of transmitting a synchronization signal based on the reflection module index transmitted in the second, fourth, sixth, ..., 2M beam search window and which reflection module is present. You can check if you are involved.

In addition, the UE and the BS each perform a random access process in the first to second M beam search windows. Specifically, the BS performs an initial beam establishment (Beam Establishment) based on a synchronization signal with the UE. For example, the BS may perform initial downlink and uplink beam configuration through a random access process based on a synchronization signal with the UE.

At this time, the UE may generate a report on the support of the reflection module. If random access not by the reflection module is attempted at least once in the entire beam search window, the UE performs beam tracking according to the first algorithm, and when only random access by the reflection module is attempted, the UE performs beam tracking according to the second algorithm can be performed.

The UE may determine the first and second algorithms based on the reflection module index. As an example, the UE may distinguish the first and second algorithms by the presence or absence of a reflection module index.

When the UE is located in the shadow area, the synchronization signal is not transmitted to the UE in the first, third, fifth, ..., 2M-1 beam search windows among the first to second M beam search windows. As a result, the UE receives only the synchronization signal including the specific reflection module index from at least one of the second, fourth, sixth, ..., 2M beam search windows, wherein the UE receives the beam according to the second algorithm. do the tracking.

In contrast, when the UE is located in the non-shaded area, the synchronization signal is transmitted to the UE in at least one of the first, third, fifth, ..., 2M-1 beam search windows among the first to second M beam search windows. can be received for In this case, the UE performs beam tracking according to the first algorithm even if it receives a synchronization signal including a specific reflection module index in at least one of the second, fourth, sixth, ..., 2M beam search windows.

As such, since an operation for additionally controlling the reflection module is required to perform the second algorithm, the algorithm is more complicated, and thus the wireless communication system can distinguish a process in which control of the reflection module is essential.

Subsequent processes are omitted because they overlap with S120, S130, S140, and S150 of FIG. 15 .

17 is a sequence diagram of a beam search method according to an embodiment of the present specification. In the description associated with FIG. 17 , the reflective module may be used interchangeably with the LIS, but the reflective module is not limited to the LIS.

Referring to FIG. 17 , the BS may change the reflection pattern of the reflection module by using the broadbeam index in the LIS-Assisted window (S1710).

Specifically, the BS may transmit a broadbeam index (eg, LIS#m) to the reflection module in the LIS-Assisted window (S1711). When the LIS receives the broadbeam index, the LIS may change the reflection pattern of the LIS based on the received broadbeam index (S1712).

Here, S1710 is used only in the LIS-Assisted window, and S1710 is omitted in the beam search window without LIS support, and S1720 is immediately performed.

On the other hand, the broadbeam index may be transmitted through a control link separated from the radio link between the BS and the UE (control link). In addition, the broadbeam index may be included in the request transmitted from the BS, as described above with reference to FIGS. 15 and 16 .

As such, in the reflective pattern changed based on the broad beam index, the LIS may reflect the incident beam as a broad beam (refer to FIG. 13(b) ).

When the reflection pattern of the LIS is changed, the BS may transmit one or more synchronization signals having different beam patterns to the UE (S1720).

Beam patterns transmitted to the UE may have different directivity as described above. Also, the synchronization signal may be an A6G synchronization signal. The synchronization signal is provided to the UE through reflection through the reflection module in the LIS-Assisted window, and is provided directly from the BS to the UE in the general beam search window.

When the reception of the synchronization signal is completed, the BS and the UE perform initial downlink and uplink beam configuration through a random access process based on the index of the synchronization signal (S1730).

FIG. 18 is a diagram for exemplarily explaining the beam search method of FIG. 17 .

Referring to FIG. 18 , a beam searching process may include one or more beam searching periodicities. A beam search window may exist in at least a part of one or more beam search periods. According to an embodiment, the beam search window is of two types. The first type is a general beam search window, and the second type is a LIS-Assited beam search window.

The beam search algorithm may be different depending on the type of the beam search window.

For example, LIS Index and LIS Beam Index are not included in the first type of beam search window. The LIS Index indicates a reflection module index indicating a specific LIS, and the LIS Beam Index indicates an index for changing the reflection pattern of the selected LIS. It can be determined whether a specific LIS is selected by the BS based on the LIS Index transmitted from the BS.

Since the BS does not transmit the LIS Index to the LIS in the first type of beam search window, one or more LISs included in the wireless communication system cannot perform an operation associated with the BS. That is, the BS only performs a beam search process in a general wireless communication system without LIS.

Referring back to FIG. 18 , when the first period including the first type of beam search window is terminated, the BS starts the second period including the second type of beam search window. In the second period, the BS transmits a request including the LIS Index through the control link.

When a set time elapses after transmitting a request including the LIS Index or a response to the request is received from the LIS, the BS may transmit a synchronization signal in different directions based on different base station beam indexes. have. The synchronization signal transmitted to the UE may be transmitted, for example, based on the first to Nth base station beam indexes (BSBeamIndex1, BSBeamIndex2, BSBeamIndex3, ..., BSBeamIndexN). The BS sweeps from BSBeamIndex1 to BSBeamIndexN and can transmit a synchronization signal in each direction.

Meanwhile, the BS may transmit the LIS Beam Index to the LIS in order to control the reflection pattern of the LIS selected based on the LIS Index. The LIS Beam Index, like the LIS Index, may be transmitted through a control link. The LIS may be changed to a reflection pattern corresponding to the received LIS Beam Index based on the LIS Beam Index. For example, if the LIS Beam Index is a Broad Beam Index, the LIS may be changed to a reflection pattern providing a broad beam.

The BS may periodically repeat the first type of beam search window and the second type of beam search window. For example, as shown in FIG. 18 , the first type of beam search window and the second type of beam search window may be sequentially repeated. As another example, although not shown in FIG. 18 , when the first type of beam search window is performed, at least one second type of beam search window may be performed until the beam search by all LISs is performed. In the above examples, there is a difference in whether the first type of beam search is performed between LIS-Assisted windows or is performed the first time.

19 is a view for explaining a beam tracking method according to an embodiment of the present specification. In the description associated with FIG. 19 , the reflective module may be used interchangeably with the LIS, but the reflective module is not limited to the LIS.

Referring to FIG. 19 , the BS may transmit a reflection pattern index of the LIS (S1910-1).

Here, the LIS is connected through a control link provided separately from the BS. The reflection pattern index is transmitted from the BS to the LIS via the control link. Here, the LIS is a predetermined LIS in the night search process, and the transmission beam of the BS is fixed in the direction of the predetermined LIS. For example, when a specific LIS is selected, the BS transmits a signal to the base station beam index directed to the location of the specific LIS, and in this case, the base station beam index is fixed.

When the selected LIS receives the reflection pattern index, it may change the reflection pattern based on the received reflection pattern index (S1920-2).

Here, the changed reflection pattern is a pattern associated with the received reflection pattern index. In addition, the reflection pattern is changed corresponding to the received reflection pattern index. In addition, the reflection pattern index used in the beam tracking process may be a narrow beam index associated with a pattern that transforms an incident beam into a narrow-shaped directional beam. The BS may implement a beam pattern formed by the LIS using one or more narrow beam indices similarly to an operation by a multi-antenna. For reference, the reflection pattern index may be used interchangeably with LISBeamIndex.

When the reflection pattern of the LIS is changed, the BS transmits a reference signal associated with the reflection pattern index to the UE (S1930-1).

As an example, the reflection pattern index may include LISBeamIndex0, LISBeamIndex1, ..., LISBeamIndexK. In this case, different reference signals correspond to respective reflection pattern indices. For example, the reference signal may be an A6G reference signal. The BS may transmit one or more A6G reference signals to the UE based on the base station beam index for the selected LIS (eg, Beam#X in FIG. 19 ).

The BS changes the reflection pattern index and adjusts the reflection pattern of the LIS, and transmits a reference signal associated with the changed reflection pattern index to the UE (S1910-K, S1920-K, S1930-K).

When the reference signal is transmitted to the UE, the reflection pattern index transmitted by the BS is incremented by one. Therefore, when the reference signal is initially transmitted according to LISBeamIndex0, thereafter, the reference signal according to LISBeamIndex1 is transmitted to the UE. As a result, the reference signals may be sequentially transmitted in the order of LISBeamIndex0, LISBeamIndex1, ..., LISBeamIndexK, and each reference signal may be different from each other according to the associated reflection pattern index. As such, the LIS may change the shape and direction of the reflected beam by adjusting the reflection pattern, and may provide a service of sweeping the narrow beam in one or more directions.

When the UE receives one or more reference signals associated with one or more reflection pattern indexes from the BS, it may transmit a Channel Status Report to the BS. At this time, the UE transmits a channel status report to the BS based on an A6G control channel or a B6G (below 6GHz) control channel.

When the BS receives the channel state report, it may determine the LIS reflection pattern that makes the channel state of the UE optimal (S1950).

Specifically, the BS may determine one beam pair representing a maximum signal strength from combinations of a plurality of transmit beams and a plurality of receive beams. In this case, the BS may store the BS Beam Index, LIS Index, and LIS Beam Index associated with the beam beam indicating the maximum output in memory.

Meanwhile, the beam tracking process is performed after the beam search process. Specifically, the beam tracking process is attempted in the beam tracking window. The bin tracking process may also be performed according to a predetermined period like the beam search process. For example, the beam tracking window may be performed at a constant period.

20 and 21 are diagrams for explaining the beam tracking method of FIG. 19 by way of example.

20 illustrates a beam tracking process in a without-LIS situation, and FIG. 21 illustrates a beam tracking process in a with-LIS situation. The without-LIS situation means a case in which LIS is not used, that is, a case in which the UE attempts random access more than once without using LIS. The with-LIS situation means a case in which the UE cannot attempt random access without LIS.

Referring to FIG. 20 , beam tracking is performed in a beam tracking window. In the without-LIS situation, the BS performs a beam sweep while changing the base station beam index. Specifically, the BS may transmit different reference signals to the UE while changing the number of transmission beams set in the beam tracking window. In this case, the BS does not transmit LIS-related indexes (eg, LIS Index, LIS Beam Index) through the control link.

Referring to FIG. 21 , the with-LIS situation is performed by a different algorithm from the without-LIS situation. For example, the main difference between the with-LIS situation and the without-LIS is whether the base station beam index is fixed or the LIS-related index is transmitted.

In the With-LIS situation, the BS Beam Index is fixed in one beam tracking window. For example, the BS Beam Index in the first beam tracking window is fixed as for the first LIS, the BS Beam Index in the second beam tracking window is fixed as for the second LIS, and in the third beam tracking window BS Beam Index of can be fixed as for the third LIS.

In this case, the BS may transmit the LIS Index through the control link to the first, second, and third LISs in the first, second, and third beam tracking windows, respectively. For example, the BS may transmit the LIS Index of LIS#1, LIS#2, and LIS#3 to the first, second, and third LISs, respectively, through the control link. As such, the LIS receiving the LIS Index may be referred to as a selected LIS or a selected LIS.

When the LIS is selected, the BS may transmit a request to control the change to one or more reflection patterns to the selected LIS. As described above, the reflection pattern may be implemented as a different pattern according to each reflection pattern index.

Accordingly, the BS may change the reflection pattern from LISBeamIndex0 to LISBeamIndexK and transmit reference signals respectively corresponding to the reflection pattern indices to the UE. The entire LISBeamIndex is swept on one beam tracking window, and sweeping may be repeated for each beam tracking window.

22 is an embodiment of a wireless communication system according to an embodiment of the present specification.

Referring to FIG. 22 , a wireless communication system to which a reflection module is applied may include one or more reflection modules, a BS, and a UE.

Here, it is assumed that one or more reflection modules exist as LIS#0 and LIS#1, and UEs are UE1 and UE2. In addition, the direction of the transmit beam is set in the BS to Beam#1 to Beam#N, and the direction of the transmit beam is set to Beam#1 to Beam#K in the LIS. However, the direction and number of beams of the BS, LIS#1, and LIS#2 are not limited to the example of FIG. 22 .

First, looking at UE2, UE2 is located on the LOS in relation to the BS. Accordingly, UE2 can be connected to the BS even if there is no LIS support.

However, since UE1 is disconnected by the wall (WALL), it cannot communicate smoothly with the BS. These issues are particularly important with the A6G.

In this case, UE1 may be connected to the BS through LIS#0. First, the BS searches for UE1 that can be accessed by LIS#0, and transmits the LIS Index through a control link provided separately to transmit information about LIS#0 to UE1, and A synchronization signal is transmitted with the BS Beam Index. Transmission of the LIS Index and transmission of Beam#1 to Beam#N are performed in the beam search window.

Through the above process, UE1 may receive LIS Index indicating LIS#0 and synchronization signal(s). UE1 may perform random access with the BS based on the BS Beam Index of the synchronization signal.

Thereafter, UE1 performs beam tracking to determine an optimal beam pair. A narrow beam having a large gain is required as the signal of the high frequency band increases. The BS transmits a reference signal based on the BS Beam Index directed to LIS#0 in the beam tracking window. The BS Beam Index oriented to LIS#0 is fixed in one beam tracking window.

The BS changes and transmits one or more reference signals in the beam tracking window. Specifically, the BS transmits the reflection pattern indexes at which the reflection pattern of LIS#0 switches to Beam#1 to Beam#K in order to determine the optimal beam pair, and each time the reflection pattern is switched, different reference signal(s) ) to UE1 through LIS#0.

UE1 transmits the channel status report generated based on the reference signals received from the BS to the BS through the A6G control channel or the B6G control channel.

The BS may determine a beam pair having an optimal signal strength based on the received channel state report.

As such, various embodiments include a decision algorithm that excludes unnecessary application of the reflection module when the UE can perform initial access and/or beam management not by the reflection module from at least one BS.

In addition, various embodiments exclude the reflection pattern search process when the signal of the BS can be received without the help of the reflection module, and additionally perform the reflection pattern search process only when access can be performed only by the reflection module. The coverage can be improved.

In addition, various embodiments do not use the reflective module only as a reflector for providing a signal to the shaded area, but perform an operation similar to beam sweeping through the reflective module, thereby determining a more optimal beam pair.

In particular, although the A6G signal is vulnerable to obstacles and distances due to path loss, etc., according to various embodiments of the present specification, a beam having a higher gain can be effectively provided to the shaded area.

On the other hand, the above-described exemplary embodiments have been described in terms of a wireless communication system including a UE, a BS, and a reflection module, but various embodiments of the present specification will be described again in terms of each of the UE, BS, and reflection module as follows. can be

Perspective embodiments of a terminal (UE)

First embodiment: In a wireless communication system using a reflective module in which a plurality of reflective elements are installed, a beam management method by a terminal comprises:

Receiving a synchronization signal for downlink synchronization from the BS in a first window;

receiving, through the reflection module, the synchronization signal provided from the BS and information on the reflection module in a second window that is distinct from the first window;

A method comprising

Second embodiment: The method according to the first embodiment, wherein the synchronization signal is a signal of an A6G band.

Embodiment 3: The method according to embodiment 1, wherein the information about the reflection module is transmitted via a control link provided between the BS and the reflection module.

Fourth embodiment: The method according to the first embodiment, wherein the information about the reflective module is a reflective module index indicating the reflective module.

Fifth embodiment: In the fourth embodiment, the synchronization signal and the reflection module index are transmitted from a direction in which the reflection module is located,

wherein the reflection module index is an index indicating a reflection module located in the direction.

Sixth embodiment: According to the fourth embodiment, repeating the first and second windows until a set condition is satisfied to collect one or more synchronization signals;

performing initial beam setup with the BS based on the collected one or more synchronization signals;

A method further comprising:

Seventh embodiment: The sixth embodiment, wherein the reflection module index increases each time a period including the first and second windows ends,

The set condition is that the reflection module index reaches a maximum value.

Eighth embodiment: The sixth embodiment, further comprising: if it is determined that there is support by the reflection module based on the initial beam setting result, receiving one or more reference signals from the BS in a third window;

generating a channel state report based on the one or more reference signals;

transmitting the channel status report to the BS;

A method further comprising:

Ninth embodiment: The method according to the eighth embodiment, wherein the one or more reference signals are classified for each reflection pattern index of the reflection module that transmits the reference signal.

Embodiment 10: The method according to embodiment 8, wherein the one or more reference signals are transmitted based on a fixed base station beam index in the third window.

Embodiment 11 The method according to embodiment 8, wherein the at least one reference signal is a signal of an A6G band.

12th embodiment: The method according to the 8th embodiment, wherein the channel status report is a signal of either an A6G band or a B6G band.

Base Station (BS) Perspective Embodiments

Embodiment 1: In a wireless communication system using a reflective module in which a plurality of reflective elements are installed, a beam management method by a base station includes:

transmitting a synchronization signal for downlink synchronization to the UE in a first window;

transmitting a request for changing a reflection pattern of the reflection module located spaced apart from the BS in a second window separated from the first window;

transmitting a synchronization signal for the downlink synchronization and information about the reflection module through the reflection module;

A method comprising

Second embodiment: The method according to the first embodiment, wherein the synchronization signal is a signal transmitted in an A6G band.

Embodiment 3: The method according to embodiment 1, wherein the information about the reflection module is transmitted to the reflection module via a control link provided between the base station and the reflection module.

Fourth embodiment: The step of transmitting the synchronization signal and the information about the reflection module is performed when the BS satisfies a set condition,

The set condition includes a first condition of receiving a response to the request, and a second condition that a set time elapses from transmission of the request.

Embodiment 5: The method according to embodiment 1, wherein the information about the reflective module is a reflective module index indicating the reflective module.

Sixth embodiment: The fifth embodiment, wherein the synchronization signal and the reflection module index are transmitted from a direction in which the reflection module is located,

wherein the reflection module index is an index indicating a reflection module located in the direction.

Seventh embodiment: According to the fifth embodiment,

wherein the reflection module index is increased based on the end of the second window.

Eighth embodiment: according to the seventh embodiment,

when the value of the reflection module index reaches a maximum value, performing initial beam setting between the BS and the UE;

a method further comprising

Ninth embodiment: According to the eighth embodiment,

When it is determined that there is support by the reflection module based on the result of the initial beam setting, one or more narrow beam indexes for adjusting the reflection pattern are reflected in a third window separated from the first and second windows. sending to the module;

A method further comprising:

10th embodiment: According to the ninth embodiment,

transmitting one or more reference signals to the UE through a reflection module in which the reflection pattern is changed;

A method further comprising:

11th embodiment: According to the 10th embodiment,

Transmitting the one or more reference signals comprises:

A method of transmitting a reference signal corresponding to the transmitted narrow beam index among the one or more reference signals whenever any one of the one or more narrow beam indexes is transmitted.

12th embodiment: according to the tenth embodiment,

upon receiving the channel status report from the UE, determining one beam pair representing the maximum signal output based on the channel status report;

A method further comprising:

Thirteenth embodiment: according to the tenth embodiment,

The one or more reference signals are distinguished by the one or more narrow beam indexes.

14th embodiment: according to the tenth embodiment,

The one or more reference signals are transmitted in a fixed direction based on a fixed base station beam index in the third window.

Fifteenth embodiment: according to the tenth embodiment,

The at least one reference signal is a signal transmitted in the A6G band.

Sixteenth embodiment: according to the tenth embodiment,

The channel status report is a signal transmitted in either the A6G band or the B6G band.

Aspect Embodiments of a Reflective Module

1st embodiment: In a wireless communication system using a reflective module in which a plurality of reflective elements are installed, the beam management method by the reflective module includes:

changing the reflection pattern upon receiving a request from the BS;

changing a synchronization signal for downlink transmitted in a first direction from the BS in a second direction and providing the same to the UE;

A method comprising

Second embodiment: According to the first embodiment,

The request is received via a control link provided separately in relation to the BS.

Third embodiment: according to the first embodiment,

The synchronization signal in the first direction and the synchronization signal in the second direction have different beam patterns.

Fourth embodiment: According to the third embodiment,

The different beam patterns of the synchronization signals in the first and second directions are determined based on a reflection pattern index included in the request.

Fifth embodiment: According to the fourth embodiment,

The reflection pattern index includes a broad beam index or one or more narrow beam indexes,

When the broad beam index is received, it is changed to a reflection pattern that reflects an incident beam in one or more directions,

When the one or more narrow beam indexes are received, it is changed into a reflection pattern that forms a beam pattern oriented in one direction corresponding to the received narrow beam index among a plurality of directions.

Embodiment 6: According to embodiment 1,

The providing step is

transmitting information about the reflection module with the synchronization signal.

Seventh embodiment: According to the sixth embodiment,

The information about the reflective module is a reflective module index indicating the reflective module.

Eighth embodiment: The reflective module of a wireless communication system using a reflective module in which a plurality of reflective elements are installed,

Memory;

transceiver;

a plurality of reflective elements; and

Processor that changes the reflection pattern by the reflective element when receiving a request from the BS, changes the synchronization signal for downlink transmitted from the BS in the first direction in the state of the changed reflection pattern in the second direction to the second direction, and provides it to the UE Containing, a reflection module.

The above-described specification can be implemented as computer-readable code on a medium in which a program is recorded. The computer-readable medium includes all kinds of recording devices in which data readable by a computer system is stored. Examples of computer-readable media include Hard Disk Drive (HDD), Solid State Disk (SSD), Silicon Disk Drive (SDD), ROM, RAM, CD-ROM, magnetic tape, floppy disk, optical data storage device, etc. There is also a carrier wave (eg, transmission over the Internet) that is implemented in the form of. Accordingly, the above detailed description should not be construed as restrictive in all respects but as exemplary. The scope of this specification should be determined by a reasonable interpretation of the appended claims, and all modifications within the scope of equivalents of this specification are included in the scope of this specification.

Claims (16)

1. In the wireless communication system using a reflection module provided with a plurality of reflection elements, the beam management method by the wireless communication system comprises:

   transmitting, by a base station (BS), a synchronization signal for downlink synchronization in a first window;

   transmitting, by the BS, a request for changing the reflection pattern of the reflection module located spaced apart from the BS at the starting point of a second window after the first window;

   changing, by the reflection module, the reflection pattern upon receiving the request; and

   transmitting, by the BS, a synchronization signal for the downlink synchronization and information on the reflection module to a user equipment (UE) through the reflection module when the condition set in the second window is satisfied;

   A method comprising
2. According to claim 1,

   The conditions set above are:

   a first condition in which the BS receives a response to the request to change the reflection pattern; and/or a second condition in which a set time elapses after sending the request.
3. According to claim 1,

   wherein the sync signal is an A6G (above 6 GHz) sync signal.
4. According to claim 1,

   Information about the reflection module,

   transmitted to the reflection module via a control link provided between the BS and the reflection module.
5. The method of claim 1,

   Information about the reflection module,

   a reflection module index indicating the reflection module.
6. 6. The method of claim 5,

   The sync signal and the reflective module index are transmitted from the direction in which the reflective module is located,

   wherein the reflection module index is an index indicating a reflection module located in the direction.
7. 6. The method of claim 5,

   When the second window is closed, the BS increments the value of the reflection module index.
8. 8. The method of claim 7,

   when the value of the reflection module index reaches the maximum value, the BS performing initial beam setting between the BS and the UE;

   A method further comprising:
9. 9. The method of claim 8,

   if it is determined that there is support by the reflection module based on the initial beam setting result, transmitting, by the BS, one or more narrow beam indexes for adjusting the reflection pattern to the reflection module in a third window;

   transmitting one or more reference signals associated with the narrow beam index;

   generating, by the UE, a channel state report based on the one or more reference signals, and transmitting the channel state report to the BS:

   determining, by the BS, one beam pair indicating a maximum signal strength based on the channel state report;

   A method further comprising:
10. 10. The method of claim 9,

    The one or more reference signals are divided by the one or more narrow beam indexes,

    Transmitting the reference signal comprises:

    When a specific narrow beam index is transmitted to the reflection module, a reference signal associated with the specific narrow beam index is transmitted to the UE.
11. 10. The method of claim 9,

    The one or more reference signals are transmitted based on a fixed base station beam index in the third window.
12. 10. The method of claim 9,

    The at least one reference signal is a signal in the A6G band.
13. 10. The method of claim 9,

    The method of claim 1, wherein the channel status report is a signal of either A6G band or B6G band.
14. 10. The method of claim 9,

    The one or more narrow beam indexes are transmitted to the reflection module via a control link provided between the BS and the reflection module.
15. In a wireless communication system using a reflective module provided with a plurality of reflective elements, the beam management method by a terminal comprises:

    Receiving a synchronization signal for downlink synchronization from the BS in a first window;

    receiving, through the reflection module, the synchronization signal provided from the BS and information on the reflection module in a second window that is distinct from the first window;

    A method comprising
16. A computer system-readable recording medium in which a program for executing the method of claim 1 in a computer system is recorded.

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