# US 12,004,027 B2 · Method and apparatus for handling radio link failure in wireless communication system

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- Number: US 12,004,027 B2
- Document ID: US12004027B2
- Status: Granted
- Kind: B2
- Application number: 17/310,526
- Filed: 2020-02-07
- Published: 2022-02-03
- Granted: 2024-06-04
- Earliest claimed: 2019-02-08
- Assignees: Samsung Electronics Co., Ltd.
- Applicants: Samsung Electronics Co., Ltd.
- Inventors: Fasil Abdul Latheef; Mangesh Abhimanyu Ingale; Himke Van Der Velde; Soenghun Kim
- Web page: https://patentgrep.com/patent/US12004027B2

## CPC

- H04W 36/0079: {in case of hand-off failure or rejection}
- H04L 69/28: Timers or timing mechanisms used in protocols
- H04W 24/10: Scheduling measurement reports {; Arrangements for measurement reports}
- H04W 36/0058: {Transmission of hand-off measurement information, e.g. measurement reports}
- H04W 36/0061: {of neighbour cell information}
- H04W 36/0085: {Hand-off measurements}
- H04W 36/305: {Handover due to radio link failure (control signalling for hand-off failure H04W36/0079)}
- H04W 36/00698: {using different RATs}
- H04W 36/00837: {Determination of triggering parameters for hand-off}
- H04W 36/302: {due to low signal strength}
- H04W 76/19: Connection re-establishment
- H04W 76/38: triggered by timers
- H04W 88/06: adapted for operation in multiple networks {or having at least two operational modes}, e.g. multi-mode terminals
- H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72)
- H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M)

## Abstract

Embodiments herein disclose a method for handling a RLF in a wireless communication system by a UE (100). The method includes receiving a measurement configuration including a second timer (150) from a SN (300). Further, the method includes configuring the UE with the second timer associated with a measurement report for a PSCell of the SN. Further, the method includes starting the second timer when the measurement report is triggered while a first timer (140) for the PSCell is running. Further, the method includes detecting an expiry of one of: the first timer and the second timer for the PSCell. Further, the method includes declaring a SCG RLF upon expiry of one of: the first timer and the second timer whichever is early. Further, the method includes initiating a SCG failure procedure towards a MN (300) upon declaring SCG RLF.

## Claims

### Claim 1

A method for handling a radio link failure (RLF) in a wireless communication system comprising a master cell group (MCG) and a secondary cell group (SCG) the method comprising:
receiving, a radio resource control (RRC) reconfiguration message including measurement configuration information for the SCG, via a signaling radio bearer 3 (SRB 3);
identifying that a measurement report type is set to event-triggered and a measurement report event for the SCG is triggered, based on report configuration information for the SCG including information indicating use of a T312 timer;
in case that the information indicating the use of the T312 timer is included in the report configuration information for the SCG and a T310 timer is running, starting the T312 timer based on the measurement configuration information for the SCG, including a value of the T312 timer;
based on an expiry of the T312 timer on a primary SCG cell (PSCell), declaring a RLF of the SCG; and
transmitting, via a signaling radio bearer 1 (SRB 1), a SCG failure message including a cause value corresponding to a failure type as the expiry of the T312 timer.

### Claim 2 (depends on 1)

The method of claim 1, wherein the SCG failure message is transmitted via MCG transmission, upon declaring the RLF of the SCG.

### Claim 3

A User Equipment (UE) configured to handle a radio link failure (RLF) in a wireless communication system comprising a master cell group (MCG) and a secondary cell group (SCG) the UE comprising:
a transceiver; and
a processor coupled with the transceiver and configured to:
receive a radio resource control (RRC) reconfiguration message including measurement configuration information for the SCG, via a signaling radio bearer 3 (SRB 3);
identify that a measurement report type is set to event-triggered and a measurement report event for the SCG is triggered, based on report configuration information for the SCG including information indicating use of a T312 timer;
in case that the information indicating the use of the T312 timer is included in the report configuration information for the SCG and a T310 timer is running, start the T312 timer based on the measurement configuration information for the SCG, including a value of the T312 timer;
based on an expiry of the T312 timer on a primary SCG cell (PSCell), declare a RLF of the SCG; and
transmit, via a signaling radio bearer 1 (SRB 1), a SCG failure message including a cause value corresponding to a failure type as the expiry of the T312 timer.

### Claim 4 (depends on 3)

The UE of claim 3, wherein the SCG failure message is transmitted via MCG transmission, upon declaring the RLF of the SCG.