IP Library › Granted Patent US 12701469

Granted Patent B2

US 12701469 · App. 18/035,836 · Granted Aug 4, 2026

Method and apparatus for mobility robustness optimization

Inventors: Lianhai Wu (Beijing, CN); Mingzeng Dai (Shanghai, CN); Yan Le (Shanghai, CN); Ran Yue (Beijing, CN); Min Xu (Beijing, CN)

Assignee: Lenovo (Beijing) Limited

H04W36/0058 H04W36/185 H04W36/362 H04W74/0816 H04W36/00837

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Quick Facts

Patent No.: US 12701469
App. No.: 18/035,836
Granted: Aug 4, 2026
Kind: B2

External Links

USPTO Patent Center↗ Full Patent PDF↗

Abstract

Embodiments of the present disclosure relate to methods and apparatuses for mobility robustness optimization. According to some embodiments of the disclosure, a method may include: performing one of the following handover procedures associated with a target cell: a handover procedure in response to receiving a handover command, a CHO procedure in response to meeting a CHO execution condition, and a DAPS handover procedure in response to receiving a DAPS handover command; accessing the target cell; storing assistant information related to a successful handover to the target cell; and transmitting the assistant information related to the successful handover to the target cell in response to a trigger condition for transmitting assistant information being met. In addition, the target BS may transmit the assistant information related to the successful handover to the source BS over the Xn interface.

Claims (164)

1 . 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:

perform a handover procedure associated with a target cell, the handover procedure comprising at least one of:

a handover procedure in response to receiving a handover command;

a conditional handover (CHO) procedure in response to meeting a CHO execution condition; or

a dual active protocol stack (DAPS) handover procedure in response to receiving a DAPS handover command;

access the target cell;

transmit, to the target cell, a radio resource control (RRC) message indicating completion of a successful handover to the target cell;

store assistant information related to the successful handover to the target cell; and

transmit, after transmitting the RRC message indicating the completion of the successful handover to the target cell, the assistant information related to the successful handover to the target cell in response to a trigger condition for transmitting the assistant information being met.

2 . The UE of claim 1 , wherein the trigger condition for transmitting the assistant information comprises at least one of:

CHO configuration being configured for the UE when the UE performs the handover procedure in response to receiving the handover command;

a number of preamble attempts in the target cell of the handover procedure being greater than a first threshold; or

a value of a physical layer problem timer being greater than a second threshold when the UE performs the handover procedure in response to receiving the handover command.

3 . The UE of claim 1 , wherein the trigger condition for transmitting the assistant information comprises at least one of:

a time interval between a CHO execution and a reception of a corresponding CHO configuration at the UE being less than a first threshold;

the time interval between the CHO execution and the reception of the corresponding CHO configuration at the UE being greater than a second threshold;

a channel quality between the UE and a source base station (BS) of the UE is greater than a third threshold when the CHO procedure is performed at the UE;

the channel quality between the UE and the source BS of the UE being greater than a fourth threshold or less than a fifth threshold when the CHO procedure is performed at the UE;

a number of consecutive in-sync indications being greater than a sixth threshold when the CHO procedure is performed at the UE;

a number of consecutive out-of-sync indications being less than a seventh threshold when the CHO procedure is performed at the UE;

a physical layer problem timer being not started when the CHO procedure is performed at the UE;

a physical layer problem timer being started when the CHO procedure is performed at the UE;

a timer for initiating failure recovery based on triggering a measurement report being not started when the CHO procedure is performed at the UE;

a channel quality of one of at least one serving beam of the UE being greater than an eighth threshold when the CHO procedure is performed at the UE;

a channel quality of each of the at least one serving beam of the UE being greater than a ninth threshold when the CHO procedure is performed at the UE;

a physical layer problem timer being started within a first period after a successful CHO;

a timer for initiating failure recovery based on triggering a measurement report being started within a second period after the successful CHO;

the number of consecutive out-of-sync indications being greater than a tenth threshold after the successful CHO; or

a number of preamble attempts in the target cell of a CHO being greater than an eleventh threshold.

4 . The UE of claim 1 , wherein the trigger condition for transmitting the assistant information comprises at least one of:

CHO configuration being configured for the UE when the UE performs the DAPS handover procedure in response to receiving the DAPS handover command;

CHO configuration being configured for the target cell associated with the DAPS handover;

CHO configuration being configured for the UE and a time to trigger (TTT) timer has started for at least one CHO candidate cell when the UE performs the DAPS handover procedure in response to receiving the DAPS handover command;

consistent uplink listen-before-talk (LBT) failures being detected on at least one uplink (UL) bandwidth part (BWP) of a primary cell of the UE;

a channel quality between the UE and a source base station (BS) of the UE being greater than a first threshold when the UE performs the DAPS handover procedure in response to receiving the DAPS handover command;

the channel quality between the UE and a source BS of the UE being greater than a second threshold and less than a third threshold when the UE performs the DAPS handover procedure in response to receiving the DAPS handover command;

a number of consecutive in-sync indications being greater than a fourth threshold when the UE performs the DAPS handover procedure in response to receiving the DAPS handover command;

a number of consecutive out-of-sync indications being less than a fifth threshold when the UE performs the DAPS handover procedure in response to receiving the DAPS handover command;

a physical layer problem timer being not started when the UE performs the DAPS handover procedure in response to receiving the DAPS handover command;

a timer for initiating failure recovery based on triggering a measurement report being not started when the UE performs the DAPS handover procedure in response to receiving the DAPS handover command;

a channel quality of one of at least one serving beam of the UE being greater than a sixth threshold when the UE performs the DAPS handover procedure in response to receiving the DAPS handover command;

a channel quality of each of the at least one serving beam of the UE being greater than a seventh threshold when the UE performs the DAPS handover procedure in response to receiving the DAPS handover command;

a physical layer problem timer being started within a first period after a successful DAPS handover;

a timer for initiating failure recovery based on triggering a measurement report being started within a second period after the successful DAPS handover;

the number of consecutive out-of-sync indications being greater than an eighth threshold after the successful DAPS handover;

a number of preamble attempts in the target cell of a DAPS handover being greater than a ninth threshold; or

a value of a physical layer problem timer being greater than a tenth threshold when the UE performs the DAPS handover procedure in response to receiving the DAPS handover command.

5 . The UE of claim 1 , wherein the at least one processor is configured to cause the UE to:

transmit, to the target cell and in response to the trigger condition for transmitting the assistant information being met, an indication comprising at least one of:

failure information being available;

assistant information associated with the successful handover triggered by the handover command being available;

assistant information associated with a successful CHO being available; or

assistant information associated with a successful DAPS handover being available.

6 . The UE of claim 5 , wherein the at least one processor is configured to cause the UE to:

receive a UE information request message from the target cell in response to the indication;

wherein to transmit the assistant information related to the successful handover comprises to transmit a UE information response message including the assistant information related to the successful handover to the target cell.

7 . The UE of claim 6 , wherein the UE information request message requests at least one of:

the failure information;

the assistant information associated with the successful handover triggered by the handover command;

the assistant information associated with the successful CHO; or

the assistant information associated with the successful DAPS handover.

8 . The UE of claim 1 , wherein the assistant information comprises at least one of:

CHO related information.

9 . The UE of claim 1 , wherein the assistant information includes at least one of:

a time interval between a CHO execution and a reception of a corresponding CHO configuration at the UE;

a value of a physical layer problem timer started after a successful CHO;

a value of a timer for initiating failure recovery based on triggering a measurement report started after the successful CHO;

a number of consecutive out-of-sync indications after the successful CHO; or

a number of preamble attempts in the target cell of a CHO.

10 . A first base station (BS) 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 first BS to:

receive, from a user equipment (UE), a radio resource control (RRC) message indicating completion of a success handover of the UE from a second BS to the first BS; and

receive, from the UE and after receiving the RRC message indicating completion of the successful handover of the UE from the second BS to the first BS, assistant information related to the successful handover of the UE from the second BS to the first BS;

wherein the successful handover comprises at least one of a successful handover triggered by a handover command, a successful conditional handover (CHO), or a successful dual active protocol stack (DAPS) handover.

11 . The first BS of claim 10 , wherein the at least one processor is configured to cause the first BS to:

receive, at the first BS from the UE, an indication of at least one of:

failure information being available;

assistant information associated with the successful handover triggered by the handover command being available;

assistant information associated with the successful CHO being available; or

assistant information associated with the successful DAPS handover being available.

12 . The first BS of claim 11 , wherein the at least one processor is configured to cause the first BS to:

transmit a UE information request message to the UE in response to the indication;

wherein to receive the assistant information related to the successful handover comprises to receive a UE information response message from the UE, wherein the UE information response message includes the assistant information related to the successful handover;

wherein the assistant information related to the successful handover includes at least one of:

CHO related information;

a time interval between a reception of a CHO configuration indicating a CHO candidate cell and a reception of the handover command or the DAPS handover command for the CHO candidate cell;

at least one identifier (ID) of at least one uplink (UL) bandwidth part (BWP) of a primary cell of the UE on which consistent uplink listen-before-talk (LBT) failures are detected;

a value of a physical layer problem timer started after the successful handover triggered by the reception of the handover command or the successful DAPS handover triggered by the reception of the DAPS handover command;

a value of a timer for initiating failure recovery based on triggering a measurement report started after the successful handover triggered by the reception of the handover command or the successful DAPS handover triggered by the reception of the DAPS handover command;

a number of consecutive out-of-sync indications after the successful handover triggered by the reception of the handover command or the successful DAPS handover triggered by the reception of the DAPS handover command;

a number of preamble attempts in a target cell of a handover triggered by the reception of the handover command or a DAPS handover triggered by the reception of the DAPS handover command;

a value of a physical layer problem timer when receiving the handover command or the DAPS handover command;

a time interval between a CHO execution and a reception of a corresponding CHO configuration at the UE;

a value of a physical layer problem timer started after the successful CHO;

a value of a timer for initiating failure recovery based on triggering a measurement report started after the successful CHO;

a number of consecutive out-of-sync indications after the successful CHO; or

a number of preamble attempts in the target cell of a CHO.

13 . The first BS of claim 12 , wherein the UE information request message requests at least one of:

the failure information;

the assistant information associated with the successful handover triggered by the handover command;

the assistant information associated with the successful CHO; or

the assistant information associated with the successful DAPS handover.

14 . The first BS of claim 10 , wherein the at least one processor is configured to cause the first BS to:

transmit an Xn message from the first BS to the second BS in response to reception of the assistant information, wherein the Xn message includes the assistant information and an indication of one or more of a successful handover report, a successful CHO report, or a successful DAPS handover report.

15 . A method performed by a user equipment (UE), the method comprising:

performing a handover procedure associated with a target cell, the handover procedure comprising at least one of:

a handover procedure in response to receiving a handover command;

a conditional handover (CHO) procedure in response to meeting a CHO execution condition; or

a dual active protocol stack (DAPS) handover procedure in response to receiving a DAPS handover command;

accessing the target cell;

transmitting, to the target cell, a radio resource control (RRC) message indicating completion of a successful handover to the target cell;

storing assistant information related to the successful handover to the target cell; and

transmitting, after transmitting the RRC message indicating the completion of the successful handover to the target cell, the assistant information related to the successful handover to the target cell in response to a trigger condition for transmitting the assistant information being met.

16 . The method of claim 15 , wherein the trigger condition for transmitting the assistant information comprises at least one of:

CHO configuration being configured for the UE when the UE performs the handover procedure in response to receiving the handover command;

a number of preamble attempts in the target cell of a handover being greater than a first threshold; or

a value of a physical layer problem timer being greater than a second threshold when the UE performs the handover procedure in response to receiving the handover command.

17 . The method of claim 15 , wherein the trigger condition for transmitting the assistant information comprises at least one of:

a time interval between a CHO execution and a reception of a corresponding CHO configuration at the UE being less than a first threshold;

the time interval between the CHO execution and the reception of a corresponding CHO configuration at the UE being greater than a second threshold;

a channel quality between the UE and a source base station (BS) of the UE is greater than a third threshold when the CHO procedure being performed at the UE;