# US 2019/0356439 A1 · Csi-rs configuration method and apparatus for beam management in wireless communication system > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2019/0356439 A1 - Document ID: US20190356439A1 - Status: Published application - Kind: A1 - Application number: 16/476,848 - Filed: 2018-01-09 - Published: 2019-11-21 - Earliest claimed: 2017-01-09 - Assignees: LG Electronics Inc. - Applicants: LG Electronics Inc. - Inventors: Kilbom LEE; Kijun KIM; Jiwon KANG; Jonghyun PARK; Minki AHN - Web page: https://patentgrep.com/patent/US20190356439A1 ## CPC - H04B 7/06958: {Multistage beam selection, e.g. beam refinement} - H04B 7/0408: using two or more beams, i.e. beam diversity - H04B 7/088: {using beam selection} - H04L 5/0023: {Time-frequency-space} - H04L 5/0048: {Allocation of pilot signals, i.e. of signals known to the receiver (allocation of control signalling H04L5/0053; use of control signalling H04L5/0091)} - H04W 72/21: in the uplink direction of a wireless link, i.e. towards the network - H04W 74/0833: Random access procedures, e.g. with 4-step access - H04B: TRANSMISSION - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) - H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72) ## Abstract According to one embodiment of the present disclosure, a method for determining a beam used in communication by a terminal in a mmWave communication system can be provided. The method for determining the beam may comprise a step of receiving CSI-RS from a base station, and a step of determining the beam on the basis of the CSI-RS. A CSI-RS resource and a CSI-RS port are determined on the basis of the CSI-RS, and the determined beam may correspond to the CSI-RS resource and the CSI-RS port. ## Claims ### Claim 1 A method of determining a beam to be used for communication by a user equipment (UE) in a millimeter wave (mmWave) communication system, the method comprising: receiving a channel state information-reference signal (CSI-RS) from a base station (BS); and determining the beam based on the CSI-RS; wherein a CSI-RS resource and a CSI-RS port are determined based on the CSI-RS, and wherein the determined beam corresponds to the CSI-RS resource and the CSI-RS port. ### Claim 2 (depends on 1) The method according to claim 1, wherein the CSI-RS resource corresponds to a primary beam, and the CSI-RS port corresponds to a secondary beam. ### Claim 3 (depends on 2) The method according to claim 2, wherein the UE acquires information about at least one primary beam and information about at least one secondary beam based on the received CSI-RS, and feeds back information about a preferred primary beam among the at least one primary beam and information about a preferred secondary beam among the at least one secondary beam to the BS. ### Claim 4 (depends on 3) The method according to claim 3, wherein the information about the preferred primary beam and the information about the preferred secondary beam are transmitted in at least one of a random access channel (RACH), a medium access control-control element (MAC-CE), or uplink data. ### Claim 5 (depends on 3) The method according to claim 3, wherein the information about the preferred primary beam is fed back as a CSI-RS resource index to the BS, and the information about the preferred secondary beam is fed back as a CSI-RS port index to the BS. ### Claim 6 (depends on 1) The method according to claim 1, wherein when the UE changes the determined beam, the UE changes the beam based on a P2 procedure and a P3 procedure, and wherein the P2 procedure is a procedure in which the beam is changed by sweeping downlink transmission beams of the BS and fixing an uplink reception beam of the UE, and the P3 procedure is a procedure in which the beam is changed by fixing a downlink transmission beam of the BS, and sweeping uplink reception beams of the UE. ### Claim 7 (depends on 6) The method according to claim 6, wherein the UE receives CSI-RS resource configuration information for the P2 procedure and the P3 procedure from the BS, and wherein the CSI-RS resource configuration information includes information about at least one of a cell identifier (ID), a transmission period, a time-domain offset, or a repetition number. ### Claim 8 (depends on 7) The method according to claim 7, wherein the BS transmits the downlink transmission beam according to the repetition number in the P3 procedure. ### Claim 9 (depends on 2) The method according to claim 2, wherein the primary beam corresponds to a wide beam or rough beam, and the secondary beam corresponds to a narrow beam or fine beam. ### Claim 10 (depends on 2) The method according to claim 2, wherein the primary beam is at least one of a synchronization signal block (SSB), a CSI-RS, or a measurement reference signal (MRS), and the secondary beam is a CSI-RS. ### Claim 11 (depends on 2) The method according to claim 2, wherein when the UE fails to detect a configured secondary beam or reports a beam recovery signal, the UE reconfigures a CSI-RS resource set or a CSI-RS resource subset by a higher-layer signal. ### Claim 12 (depends on 11) The method according to claim 11, wherein the UE requests changing of the CSI-RS resource set or the CSI-RS resource subset by at least one of a random access channel (RACH), scheduling request (SR), or a physical uplink control channel (PUCCH). ### Claim 13 (depends on 1) The method according to claim 1, wherein the CSI-RS is a reference signal used for beam management, and wherein the CSI-RS corresponds to at least one of an MRS or an SSB. ### Claim 14 A user equipment (UE) for determining a beam to be sued for communication in a millimeter wave (mmWave) communication system, the UE comprising: a receiver configured to receive a signal from an external device; a transmitter configured to transmit a signal to an external device; and a processor configured to control the receiver and the transmitter, wherein the processor is configured to receive a channel state information-reference signal (CSI-RS) from a base station (BS) through the receiver, and to determine the beam based on the CSI-RS; wherein a CSI-RS resource and a CSI-RS port are determined based on the CSI-RS, and wherein the determined beam corresponds to the CSI-RS resource and the CSI-RS port. ### Claim 15 (depends on 14) The UE according to claim 14, wherein the CSI-RS resource corresponds to a primary beam, and the CSI-RS port corresponds to a secondary beam. ### Claim 16 (depends on 15) The UE according to claim 15, wherein the processor is configured to acquire information about at least one primary beam and information about at least one secondary beam based on the received CSI-RS, and feed back information about a preferred primary beam among the at least one primary beam and information about a preferred secondary beam among the at least one secondary beam to the BS. ### Claim 17 (depends on 16) The UE according to claim 16, wherein the information about the preferred primary beam and the information about the preferred secondary beam are transmitted in at least one of a random access channel (RACH), a medium access control-control element (MAC-CE), or uplink data. ### Claim 18 (depends on 16) The UE according to claim 16, wherein the information about the preferred primary beam is fed back as a CSI-RS resource index to the BS, and the information about the preferred secondary beam is fed back as a CSI-RS port index to the BS. ### Claim 19 (depends on 14) The UE according to claim 14, wherein when the UE changes the determined beam, the UE changes the beam based on a P2 procedure and a P3 procedure, and wherein the P2 procedure is a procedure in which the beam is changed by sweeping downlink transmission beams of the BS and fixing an uplink reception beam of the UE, and the P3 procedure is a procedure in which the beam is changed by fixing a downlink transmission beam of the BS, and sweeping uplink reception beams of the UE. ### Claim 20 (depends on 19) The UE according to claim 19, wherein the processor is configured to receive CSI-RS resource configuration information for the P2 procedure and the P3 procedure from the BS, and wherein the CSI-RS resource configuration information includes information about at least one of a cell identifier (ID), a transmission period, a time-domain offset, or a repetition number.