# US 2019/0246290 A1 · Method and device for performing beam refinement 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 2019/0246290 A1 - Document ID: US20190246290A1 - Status: Published application - Kind: A1 - Application number: 16/331,955 - Filed: 2017-09-08 - Published: 2019-08-08 - Earliest claimed: 2016-09-09 - Assignees: LG Electronics Inc. - Applicants: LG Electronics Inc. - Inventors: Kilbom LEE; Kijun KIM; Suckchel YANG - Web page: https://patentgrep.com/patent/US20190246290A1 ## CPC - H04W 16/28: using beam steering - H04B 7/0617: {for beam forming} - H04B 7/06958: {Multistage beam selection, e.g. beam refinement} - H04W 72/044: based on the type of the allocated resource - H04W 72/23: in the downlink direction of a wireless link, i.e. towards a terminal - H04W 74/0833: Random access procedures, e.g. with 4-step access - H04W 76/10: Connection setup - H04W 74/0838: using contention-free random access [CFRA] - H04W 76/19: Connection re-establishment - H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72) - H04B: TRANSMISSION ## Abstract A method for a terminal performing beam refinement in an mmWave communication system can be provided according to an embodiment of the present description. A method for a terminal performing beam refinement can comprise the steps of: transmitting a RACH preamble to a base station; receiving a RACH response from the base station; transmitting an RRC connection request message to the base station; and receiving a response message to the RRC connection request message. If beam inconsistency occurs in the terminal, ID information of a pre-connected terminal can be comprised in a terminal ID field of the RRC connection request message. ## Claims ### Claim 1 A method of performing beam refinement by a User Equipment (UE) in an mmWave communication system, the method comprising: transmitting a Random Access CHannel (RACH) preamble to a base station; receiving an RACH response from the base station; transmitting an RRC connection request message to the base station; and receiving a response message in response to the RRC connection request message, wherein when a beam mismatch occurs in the user equipment, ID information of the already-connected user equipment is included in a UE ID field of the RRC connection request message. ### Claim 2 (depends on 1) The method of claim 1, wherein the base station detects the beam mismatch based on the UE ID field. ### Claim 3 (depends on 2) The method of claim 2, wherein when the base station detects the beam mismatch, the user equipment receives the response message including beam change indication information in response to the RRC connection request message. ### Claim 4 (depends on 3) The method of claim 3, wherein at least one of a Channel State Information-Reference Signal (CSI-RS) request field and Channel State Information (CSI) is included in the RRC connection request message. ### Claim 5 (depends on 4) The method of claim 4, wherein when the CSI-RS request field is set to a first value, the user equipment receives information on a CSI-RS from the base station and wherein the information on the CSI-RS is received through at least one of Downlink Control Information (DCI) and Medium Access Control-Control Element (MAC-CE). ### Claim 6 (depends on 5) The method of claim 5, wherein at least one of a CSI-RS process reuse field, a CSI-RS resource allocation field and a CSI-RS process selection field is received together with the information on the CSI-RS. ### Claim 7 (depends on 6) The method of claim 6, wherein the CSI-RS resource allocation field indicates time and frequency resource information for transmitting the CSI-RS and wherein the CSI process selection field indicates a process used for the CSI-RS transmission. ### Claim 8 (depends on 7) The method of claim 7, wherein if the CSI-RS process reuse field is set to a first value, scheduling information on CSI-RS process configuration is received together with the information on the CSI-RS. ### Claim 9 (depends on 8) The method of claim 8, wherein the CSI information is Beam State Information (BSI) and wherein the CSI-RS is a Beam Refinement Reference Signal (BRRS). ### Claim 10 (depends on 9) The method of claim 9, wherein the CSI-RS request field is a BRRS request field, wherein the CSI-RS process reuse filed is a BRRS process reuse field, wherein the CSI-RS resource allocation field is a BRRS resource allocation field, wherein the CSI-RS process selection field is a BRRS process selection field, and wherein the CSI-RS process configuration is BRRS process configuration. ### Claim 11 A user equipment performing beam refinement in an mmWave communication system, the user equipment comprising: a receiving unit receiving a signal from an external device; a transmitting unit transmitting the signal to the external device; and a processor configured to control the receiving unit and the transmitting unit, wherein the processor is further configured to transmit a Random Access CHannel (RACH) preamble to a base station using the transmitting unit, receive an RACH response from the base station using the receiving unit, transmit an RRC connection request message to the base station using the transmitting unit, and receive a response message in response to the RRC connection request message using the receiving unit and wherein when a beam mismatch occurs in the user equipment, ID information of the already-connected user equipment is included in a User Equipment (UE) ID field of the RRC connection request message. ### Claim 12 (depends on 11) The user equipment of claim 11, wherein the base station detects the beam mismatch based on the UE ID field. ### Claim 13 (depends on 12) The user equipment of claim 12, wherein when the base station detects the beam mismatch, the user equipment receives the response message including beam change indication information in response to the RRC connection request message. ### Claim 14 (depends on 13) The user equipment of claim 13, wherein at least one of a Channel State Information-Reference Signal (CSI-RS) request field and Channel State Information (CSI) is included in the RRC connection request message. ### Claim 15 (depends on 14) The user equipment of claim 14, wherein when the CSI-RS request field is set to a first value, the user equipment receives information on a CSI-RS from the base station and wherein the information on the CSI-RS is received through at least one of Downlink Control Information (DCI) and Medium Access Control-Control Element (MAC-CE). ### Claim 16 (depends on 15) The user equipment of claim 15, wherein at least one of a CSI-RS process reuse field, a CSI-RS resource allocation field and a CSI-RS process selection field is received together with the information on the CSI-RS. ### Claim 17 (depends on 16) The user equipment of claim 16, wherein the CSI-RS resource allocation field indicates time and frequency resource information for transmitting the CSI-RS and wherein the CSI process selection field indicates a process used for the CSI-RS transmission. ### Claim 18 (depends on 17) The user equipment of claim 17, wherein when the CSI-RS process reuse field is set to a first value, scheduling information on CSI-RS process configuration is received together with the information on the CSI-RS. ### Claim 19 (depends on 18) The user equipment of claim 18, wherein the CSI information is Beam State Information (BSI) and wherein the CSI-RS is a Beam Refinement Reference Signal (BRRS). ### Claim 20 (depends on 19) The user equipment of claim 19, wherein the CSI-RS request field is a BRRS request field, wherein the CSI-RS process reuse filed is a BRRS process reuse field, wherein the CSI-RS resource allocation field is a BRRS resource allocation field, wherein the CSI-RS process selection field is a BRRS process selection field, and wherein the CSI-RS process configuration is BRRS process configuration.