# US 12,604,242 B2 · Methods and apparatuses for a mobility robustness optimization (MRO) mechanism of an Inter-RAT handover procedure

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- Number: US 12,604,242 B2
- Document ID: US12604242B2
- Status: Granted
- Kind: B2
- Application number: 18/007,181
- Filed: 2020-07-28
- Published: 2023-07-27
- Granted: 2026-04-14
- Earliest claimed: 2020-07-28
- Assignees: Lenovo (Beijing) Limited
- Applicants: Lenovo (Beijing) Limited
- Inventors: Lianhai Wu
- Web page: https://patentgrep.com/patent/US12604242B2

## CPC

- H04W 36/0079: {in case of hand-off failure or rejection}
- H04W 36/00226: {wherein the core network technologies comprise IP multimedia system [IMS], e.g. single radio voice call continuity [SRVCC]}
- H04W 36/00837: {Determination of triggering parameters for hand-off}
- H04W 76/19: Connection re-establishment
- H04W 76/30: Connection release
- H04W 76/18: Management of setup rejection or failure
- H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72)

## Abstract

Embodiments of the present application relate to methods and apparatuses for a mobility robustness optimization (MRO) mechanism of an inter-radio access technology (RAT) handover procedure. According to an embodiment of the present application, a method can include: receiving a mobility command message from a source new radio (NR) cell, wherein the mobility command message includes an identifier (ID) of a target cell, and the target cell is at least one of an evolved universal terrestrial radio access network (E-UTRAN) cell and an universal terrestrial radio access network (UTRAN) cell; determining whether a timer for initiating failure recovery based on triggering a measurement report (e.g., timer T312) is running; and in response to the timer being running, stopping the timer. Furthermore, radio link failure report (RLF) information is transmitted to a network in response to the failure of Inter-RAT handover from NR to E-UTRAN and UTRAN.

## Claims

### Claim 1

An apparatus for wireless communication, comprising:
at least one memory; and
at least one processor coupled with the at least one memory and configured to cause the apparatus to:
receive a mobility command message from a source new radio (NR) cell, wherein the mobility command message includes an identifier (ID) of a target cell, and the target cell is at least one of an evolved universal terrestrial radio access network (E-UTRAN) cell and a universal terrestrial radio access network (UTRAN) cell;
determine whether a timer for initiating failure recovery based on triggering a measurement report is running;
when the timer is running, stop the timer;
perform a handover procedure to the target cell;
in response to an occurrence of a handover failure during the handover procedure, perform a cell selection procedure and select a UTRAN cell as a candidate cell; and
initiate a radio resource control (RRC) re-establishment procedure to the selected candidate cell.

### Claim 2 (depends on 1)

The apparatus of claim 1, wherein the at least one processor is further configured to cause the apparatus to:
receive an RRC reconfiguration message including conditional handover (CHO) configuration information associated with the one or more candidate cells;
determine whether the selected candidate cell is configured with the CHO configuration information; and
in response to the selected candidate cell being configured with the CHO configuration information, perform CHO procedure to the selected candidate cell.

### Claim 3 (depends on 1)

The apparatus of claim 1, wherein the at least one processor is further configured to cause the apparatus to:
in response to the occurrence of the handover failure, transmit radio link failure (RLF) report information.

### Claim 4 (depends on 3)

The apparatus of claim 3, wherein, in response to the mobility command message including a voice fallback indication, the RLF report information includes an indicator to indicate that the handover procedure is used for a voice fallback operation.

### Claim 5 (depends on 3)

The apparatus of claim 3, wherein the apparatus is a user equipment (UE), wherein the RLF report information is transmitted to a base station (BS) serving the UE, and wherein the BS forwards a message including the RLF report information to a source BS associated with the source NR cell.

### Claim 6

An apparatus for wireless communication, comprising:
at least one memory; and
at least one processor coupled with the at least one memory and configured to cause the apparatus to:
receive a mobility command message from a source new radio (NR) cell, wherein the mobility command message includes an identifier (ID) of a target cell, and the target cell is at least one of an evolved universal terrestrial radio access network (E-UTRAN) cell and a universal terrestrial radio access network (UTRAN) cell;
determine whether a timer for initiating failure recovery based on triggering a measurement report is running;
when the timer is running, stop the timer;
perform a handover procedure to the target cell; and
in response to an occurrence of a handover failure during the handover procedure, transmit radio link failure (RLF) report information,
wherein the RLF report information includes an indicator to indicate that the handover procedure is used for a voice fallback operation when the mobility command message including a voice fallback indication.

### Claim 7 (depends on 6)

The apparatus of claim 6, wherein, in response to the occurrence of the handover failure during the handover procedure, the at least one processor is configured to cause the apparatus to:
perform a cell selection procedure and select a candidate cell; and
initiate a radio resource control (RRC) re-establishment procedure to the selected candidate cell.

### Claim 8 (depends on 7)

The apparatus of claim 7, wherein the selected candidate cell is at least one of an NR cell, a E-UTRAN cell, and a UTRAN cell.

### Claim 9 (depends on 7)

The apparatus of claim 7, wherein the at least one processor is further configured to cause the apparatus to:
receive an RRC reconfiguration message including conditional handover (CHO) configuration information associated with one or more candidate cells;
determine whether the selected candidate cell is configured with the CHO configuration information; and
in response to the selected candidate cell being configured with the CHO configuration information, perform a CHO procedure to the selected candidate cell.

### Claim 10

A user equipment (UE) for wireless communication, comprising:
at least one memory; and
at least one processor coupled with the at least one memory and configured to cause the UE to:
receive a mobility command message from a source new radio (NR) cell, wherein the mobility command message includes an identifier (ID) of a target cell, and the target cell is at least one of an evolved universal terrestrial radio access network (E-UTRAN) cell and a universal terrestrial radio access network (UTRAN) cell;
determine whether a timer for initiating failure recovery based on triggering a measurement report is running;
when the timer is running, stop the timer;
perform a handover procedure to the target cell;
in response to an occurrence of a handover failure during the handover procedure:
perform a cell selection procedure and select a UTRAN cell as a candidate cell;
initiate a radio resource control (RRC) re-establishment procedure to the selected candidate cell; and
transmit radio link failure (RLF) report information to a base station (BS) serving the UE.