# US 10,772,045 B2 · Method and apparatus for controlling uplink power in RACH-less handover > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,772,045 B2 - Document ID: US10772045B2 - Status: Granted - Kind: B2 - Application number: 16/098,117 - Filed: 2017-04-25 - Published: 2019-05-16 - Granted: 2020-09-08 - Earliest claimed: 2016-05-01 - Assignees: LG Electronics Inc. - Applicants: LG Electronics Inc. - Inventors: Youngdae Lee; Gwanmo Ku; Sangwon Kim - Web page: https://patentgrep.com/patent/US10772045B2 ## CPC - H04W 52/14: Separate analysis of uplink or downlink - H04W 36/0064: {of control information between different access points} - H04W 52/247: {where the output power of a terminal is based on a path parameter sent by another terminal} - H04W 52/325: {Power control of control or pilot channels} - H04W 52/36: with a discrete range or set of values, e.g. step size, ramping or offsets - H04W 52/40: during macro-diversity or soft handoff - H04W 52/48: during retransmission after error or non-acknowledgment - H04W 52/50: at the moment of starting communication in a multiple access environment - H04W 76/19: Connection re-establishment - H04W 76/20: Manipulation of established connections - H04W 36/08: Reselecting an access point - H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72) ## Abstract Provided are a method for a terminal controlling uplink power in a rando access channel-less (RACH-less) handover, and an apparatus for supporting same. The method may comprise the steps of: receiving, from a source base station, an RRC connection reconfiguration message including an uplink grant; transmitting, to a target base station using a first transmission power, an RRC connection reconfiguration complete message, on the basis of the uplink grant; receiving, from the target base station, a NACK corresponding to the RRC connection reconfiguration complete message; ramping the first transmission power to a second transmission power; and transmitting the RRC connection reconfiguration complete message using the ramped second transmission power. ## Claims ### Claim 1 A method for controlling uplink power in a random access channel (RACH)-less handover by a user equipment (UE), the method comprising: receiving, from a source base station, a radio resource control (RRC) reconfiguration message including an uplink grant and power setting information on first transmission power and power ramping, wherein the uplink grant and the power setting information are determined by a target base station; transmitting, to the target base station, an RRC reconfiguration complete message with the first transmission power based on the uplink grant and the power setting information; receiving non-acknowledgement (NACK) from the target base station in response to the RRC reconfiguration complete message; ramping the first transmission power to second transmission power based on the power setting information which is determined by the target base station; and transmitting the RRC reconfiguration complete message with the ramped second transmission power. ### Claim 2 (depends on 1) The method of claim 1, further comprising: receiving ramping information in response to the RRC reconfiguration complete message. ### Claim 3 (depends on 2) The method of claim 2, wherein the ramping information includes a ramping level for ramping the first transmission power to the second transmission power. ### Claim 4 (depends on 3) The method of claim 3, wherein the second transmission power is ramped from the first transmission power based on the ramping level. ### Claim 5 (depends on 2) The method of claim 2, wherein the ramping information includes information which informs the UE whether power ramping will be stopped or not. ### Claim 6 (depends on 2) The method of claim 2, wherein the NACK and the ramping information are received from the target base station through a physical hybrid ARQ indicator channel (PHICH). ### Claim 7 (depends on 1) The method of claim 1, wherein the RRC reconfiguration complete message is transmitted to the target base station through a physical uplink shared channel (PUSCH). ### Claim 8 (depends on 1) The method of claim 1, wherein the RACH-less handover is a handover procedure in which the UE skips a random access procedure for the target base station. ### Claim 9 (depends on 1) The method of claim 1, wherein the uplink grant is transmitted from the target base station to the source base station by being included in a handover request acknowledgement (ACK) message. ### Claim 10 (depends on 1) The method of claim 1, wherein the uplink grant is pre-allocated to the UE through the RRC reconfiguration message. ### Claim 11 A user equipment (UE) for controlling uplink power in a random access channel (RACH)-less handover, the UE comprising: a memory; a transceiver; and a processor coupling the memory and the transceiver, wherein the processor is configured to: control the transceiver to receive, from a source base station, a radio resource control (RRC) reconfiguration message including an uplink grant and power setting information on first transmission power and power ramping, wherein the uplink grant and the power setting information are determined by a target base station; control the transceiver to transmit, to the target base station, an RRC reconfiguration complete message with the first transmission power based on the uplink grant and the power setting information; control the transceiver to receive NACK from the target base station in response to the RRC reconfiguration complete message; ramp the first transmission power to second transmission power based on the power setting information which is determined by the target base station; and control the transceiver to transmit the RRC reconfiguration complete message with the ramped second transmission power. ### Claim 12 (depends on 11) The UE of claim 11, wherein the processor is configured to control the transceiver to receive ramping information in response to the RRC reconfiguration complete message. ### Claim 13 (depends on 12) The UE of claim 12, wherein the ramping information includes a ramping level for ramping the first transmission power to the second transmission power. ### Claim 14 (depends on 13) The UE of claim 13, wherein the second transmission power is ramped from the first transmission power based on the ramping level. ### Claim 15 (depends on 12) The UE of claim 12, wherein the ramping information includes information which informs the UE whether power ramping will be stopped or not. ### Claim 16 (depends on 12) The UE of claim 12, wherein the NACK and the ramping information are received from the target base station through a physical hybrid ARQ indicator channel (PHICH).