# US 2019/0174384 A1 · Method for changing serving cell in wireless communication system and apparatus therefor > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2019/0174384 A1 - Document ID: US20190174384A1 - Status: Published application - Kind: A1 - Application number: 16/324,845 - Filed: 2017-08-14 - Published: 2019-06-06 - Earliest claimed: 2016-08-12 - Assignees: LG Electronics Inc. - Applicants: LG Electronics Inc. - Inventors: Myoungseob KIM; Hanbyul SEO; Youngtae KIM; Seungmin LEE; Youngdae LEE; Yunjung Yl - Web page: https://patentgrep.com/patent/US20190174384A1 ## CPC - H04W 36/0061: {of neighbour cell information} - H04W 36/0069: {in case of dual connectivity, e.g. decoupled uplink/downlink} - H04W 36/304: {due to measured or perceived resources with higher communication quality} - H04W 56/001: {Synchronization between nodes} - H04W 56/0015: {one node acting as a reference for the others} - H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72) ## Abstract Disclosed are a method for changing a serving cell in a wireless communication system and an apparatus therefor. Specifically, the method performed by a UE may include: transmitting, to a serving cell, a measurement report for signals received from the serving cell and one or more cells; when a measurement value for a signal received from at least one cell among the one or more cells satisfies a predetermined specific triggering condition, receiving, from the serving cell, information representing that the at least one cell corresponds to a candidate cell for changing the serving cell; and performing synchronization for at least one of a downlink or an uplink with the at least one cell, by transmitting a specific uplink signal to the at least one cell. ## Claims ### Claim 1 A method for changing a serving cell in a wireless communication system, the method performed by a UE, comprising: transmitting, to a serving cell, a measurement report for signals received from the serving cell and one or more cells; when a measurement value for a signal received from at least one cell among the one or more cells satisfies a predetermined specific triggering condition, receiving, from the serving cell, information representing that the at least one cell corresponds to a candidate cell for changing the serving cell; and performing synchronization for at least one of a downlink or an uplink with the at least one cell, by transmitting a specific uplink signal to the at least one cell, wherein the at least one cell is included in a candidate cell list configured for changing the serving cell. ### Claim 2 (depends on 1) The method of claim 1, wherein, when the specific uplink signal is a preamble for a random access, the performing of the synchronization comprises: receiving, from the at least one cell, at least one of resource allocation information related with uplink transmission or a value for a timing advance. ### Claim 3 (depends on 2) The method of claim 2, wherein the synchronization is performed while maintaining a connection between the UE and the serving cell. ### Claim 4 (depends on 3) The method of claim 3, wherein, the performing of the synchronization further comprises: transmitting identification information of the UE to the at least one cell, and wherein the identification information of the UE includes a specific number of contiguous bits indicating that the synchronization is performed while maintaining the connection between the UE and the serving cell. ### Claim 5 (depends on 3) The method of claim 3, wherein the performing of the synchronization further comprises: transmitting, to the at least one cell, indication information representing that the synchronization is performed while maintaining the connection between the UE and the serving cell, and wherein the indication information is transmitted in a predetermined specific resource region of an uplink channel. ### Claim 6 (depends on 3) The method of claim 3, further comprising: receiving, from the serving cell, at least one of an identifier of the at least one cell, a dedicated preamble for the at least one cell, or a system information block for the at least one cell. ### Claim 7 (depends on 3) The method of claim 3, further comprising: transmitting, to the serving cell, a measurement report for a signal received from a specific cell; receiving, from the serving cell, information indicating the specific cell to be configured as a new serving cell, when a measurement value for the signal received from the specific cell satisfies a triggering condition related with handover and the specific cell is included in the candidate cell list; and performing uplink transmission to the new serving cell by configuring the specific cell as the new serving cell. ### Claim 8 (depends on 7) The method of claim 7, wherein the information indicating the specific cell to be configured as the new serving cell is transmitted in subframe #n, and wherein control information related with the uplink transmission is transmitted in subframe #n+k from the specific cell. ### Claim 9 (depends on 3) The method of claim 3, further comprising: transmitting, to the serving cell, a measurement report for a signal received from a specific cell; receiving, from the serving cell, a handover command to the specific cell, when a measurement value for the signal received from the specific cell satisfies the triggering condition related with handover and the specific cell is not included in the candidate cell list; and performing the synchronization for the specific cell. ### Claim 10 (depends on 3) The method of claim 3, further comprising: updating at least one of a value for the timing advance or a value for a power control for the at least one cell, through the uplink transmission periodically configured with respect to the at least one cell. ### Claim 11 (depends on 10) The method of claim 10, wherein, when the uplink transmission for the serving cell overlaps with the periodically configured uplink transmission, the uplink transmission for the serving cell is preferentially performed to the periodically configured uplink transmission. ### Claim 12 (depends on 3) The method of claim 3, wherein the predetermined specific triggering condition includes the triggering condition for configuring the candidate cell list. ### Claim 13 A UE changing a serving cell in a wireless communication system, the UE comprising: a radio frequency (RF) unit transmitting and receiving a radio signal; and a processor functionally connected to the RF unit, wherein the processor controls to transmit, to a serving cell, a measurement report for signals received from the serving cell and one or more cells, when a measurement value for a signal received from at least one cell among the one or more cells satisfies a predetermined specific triggering condition, receive, from the serving cell, information representing that the at least one cell corresponds to a candidate cell for changing the serving cell, and perform synchronization for at least one of a downlink or an uplink with the at least one cell, by transmitting a specific uplink signal to the at least one cell, wherein the at least one cell is included in a candidate cell list configured for changing the serving cell, and wherein the synchronization is performed while maintaining a connection between the UE and the serving cell.