# US 11,910,248 B2 · Method and apparatus for performing handover in a next-generation communication system > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,910,248 B2 - Document ID: US11910248B2 - Status: Granted - Kind: B2 - Application number: 17/560,046 - Filed: 2021-12-22 - Published: 2022-06-30 - Granted: 2024-02-20 - Earliest claimed: 2020-12-24 - Assignees: Samsung Electronics Co., Ltd. - Applicants: Samsung Electronics Co., Ltd. - Inventors: Sangyeob Jung - Web page: https://patentgrep.com/patent/US11910248B2 ## CPC - H04W 24/02: Arrangements for optimising operational condition - H04W 36/0079: {in case of hand-off failure or rejection} - H04W 36/0083: {Determination of parameters used for hand-off, e.g. generation or modification of neighbour cell lists} - H04W 36/08: Reselecting an access point - H04W 36/1443: {between licensed networks} - H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72) ## Abstract The disclosure relates to a 5G or pre-5G communication system for supporting a data transmission rate higher than a 4G communication system such as LTE. A method performed by a UE in a communication system includes: receiving, from a base station associated with NR, a command message for inter-RAT handover from the NR to a target RAT, wherein the command message includes information on a type of the target RAT; performing a procedure associated with the inter-RAT handover based on the command message; in case that a failure condition for the inter-RAT handover is satisfied, identifying that the inter-RAT handover fails; and in case that the type of the target RAT is set to EUTRA and the UE supports a radio link failure report for inter-RAT MRO EUTRA, storing handover failure information in a variable for the radio link failure report based on an identification that the inter-RAT handover fails. ## Claims ### Claim 1 A method performed by a user equipment (UE) in a communication system, the method comprising: receiving, from a base station associated with new radio-radio access (NR), a command message for inter-radio access technology (RAT) handover from the NR to a target RAT, wherein the command message includes information on a type of the target RAT; performing a procedure associated with the inter-RAT handover based on the command message; in case that a failure condition for the inter-RAT handover is satisfied, identifying that the inter-RAT handover fails; and in case that the type of the target RAT is set to evolved universal terrestrial radio access (EUTRA) and the UE supports a radio link failure report for inter-RAT mobility robustness optimization (MRO) EUTRA, storing handover failure information in a variable for the radio link failure report based on an identification that the inter-RAT handover fails. ### Claim 2 (depends on 1) The method of claim 1, wherein the failure condition for the inter-RAT handover is satisfied when: the UE does not succeed in establishing a connection to the target RAT; the UE is unable to comply with any part of a configuration included in the command message; or a protocol error occurs in inter-RAT information included in the command message, the protocol error causing the UE to fail a procedure applicable for the target RAT. ### Claim 3 (depends on 1) The method of claim 1, wherein storing the handover failure information comprises: including NR previous cell information in previous cell identifier (ID) information of the variable for the radio link failure report; and setting the NR previous cell information to a global cell identity and a tracking area code of a primary cell (PCell) where the command message was received. ### Claim 4 (depends on 1) The method of claim 1, wherein storing the handover failure information comprises: setting time connection failure information of the variable for the radio link failure report to an elapsed time since reception of the command message. ### Claim 5 (depends on 1) The method of claim 1, wherein storing the handover failure information comprises: in case that the command message is associated with the failed inter-RAT handover from the NR to the EUTRA and the UE supports the radio link failure report for the inter-RAT MRO EUTRA, setting EUTRA failed primary cell (PCell) identifier (ID) information of the variable for the radio link failure report to a global cell identity and a tracking area code. ### Claim 6 (depends on 1) The method of claim 1, wherein storing the handover failure information comprises: in case that the command message is associated with the failed inter-RAT handover from the NR to the EUTRA and the UE supports the radio link failure report for the inter-RAT MRO EUTRA, setting EUTRA failed primary cell (PCell) identifier (ID) information of the variable for the radio link failure report to a physical cell identity and a carrier frequency of a target PCell of the failed inter-RAT handover. ### Claim 7 (depends on 1) The method of claim 1, further comprising: in case that the inter-RAT handover is successfully completed, skipping stopping a timer associated with logged measurement. ### Claim 8 (depends on 1) The method of claim 1, further comprising: in case that connection failure type information of the variable for the radio link failure report is set to a handover failure and a failed handover is an intra-RAT handover, setting common random-access related information of the variable for the radio link failure report to include random-access related information used in a random access procedure. ### Claim 9 A user equipment (UE) in a communication system, the UE comprising: a transceiver; and a controller operably coupled to the transceiver, the controller configured to: receive, from a base station associated with new radio-radio access (NR) via the transceiver, a command message for inter-radio access technology (RAT) handover from the NR to a target RAT, wherein the command message includes information on a type of the target RAT, perform a procedure associated with the inter-RAT handover based on the command message, in case that a failure condition for the inter-RAT handover is satisfied, identify that the inter-RAT handover fails, and in case that the type of the target RAT is set to evolved universal terrestrial radio access (EUTRA) and the UE supports a radio link failure report for inter-RAT mobility robustness optimization (MRO) EUTRA, store handover failure information in a variable for the radio link failure report based on an identification that the inter-RAT handover fails. ### Claim 10 (depends on 9) The UE of claim 9, wherein the failure condition for the inter-RAT handover is satisfied when: the UE does not succeed in establishing a connection to the target RAT; the UE is unable to comply with any part of a configuration included in the command message; or a protocol error occurs in inter-RAT information included in the command message, the protocol error causing the UE to fail a procedure applicable for the target RAT. ### Claim 11 (depends on 9) The UE of claim 9, wherein the controller is configured to: include NR previous cell information in previous cell identifier (ID) information of the variable for the radio link failure report, and set the NR previous cell information to a global cell identity and a tracking area code of a primary cell (PCell) where the command message was received. ### Claim 12 (depends on 9) The UE of claim 9, wherein the controller is configured to: set time connection failure information of the variable for the radio link failure report to an elapsed time since reception of the command message. ### Claim 13 (depends on 9) The UE of claim 9, wherein the controller is configured to: in case that the command message is associated with the failed inter-RAT handover from the NR to the EUTRA and the UE supports the radio link failure report for the inter-RAT MRO EUTRA, set EUTRA failed primary cell (PCell) identifier (ID) information of the variable for the radio link failure report to a global cell identity and a tracking area code. ### Claim 14 (depends on 9) The UE of claim 9, wherein the controller is configured to: in case that the command message is associated with the failed inter-RAT handover from the NR to the EUTRA and the UE supports the radio link failure report for the inter-RAT MRO EUTRA, set EUTRA failed primary cell (PCell) identifier (ID) information of the variable for the radio link failure report to a physical cell identity and a carrier frequency of a target PCell of the failed inter-RAT handover. ### Claim 15 (depends on 9) The UE of claim 9, wherein the controller is further configured to: in case that the inter-RAT handover is successfully completed, skip stopping a timer associated with logged measurement. ### Claim 16 (depends on 9) The UE of claim 9, wherein the controller is further configured to: in case that connection failure type information of the variable for the radio link failure report is set to a handover failure and a failed handover is an intra-RAT handover, set common random-access related information of the variable for the radio link failure report to include random-access related information used in a random access procedure.