Devices, methods, apparatuses, and computer readable media for mobility robustness optimization

Abstract

Mobility robustness optimization in a conditional handover (CHO) with candidate secondary cell group (SCG) procedure. A terminal device receiving, from a first network node, a configuration message comprising at least one condition each for a conditional handover and for a cell addition or change; evaluating whether the conditions are met; detecting a failure of a connection with a third network node before the conditions are both met; and transmitting a failure report to the first network node. A second network node transmitting to a first network node at least one condition for a cell addition or change; receiving from the first network node, a failure report for connection between a terminal device and a third network node when a condition was not met; and either transmitting the failure report to an operations administration and maintenance entity, or determining adaptation information for the condition for the cell addition or change. A first network node transmitting, to a terminal device, a configuration message comprising at least one condition each for a conditional handover and for a cell addition or change; receiving, from the terminal device, a failure report for connection between the terminal device and a third network node when at least one of the conditions was not met; and either transmitting the failure report to either an operations administration and maintenance entity or to a second network node which determined the at least one condition, or determining adaptation information for the conditional handover.

Description

[0001] Various example embodiments described herein generally relate to communication technologies, and more particularly, to devices, methods, apparatuses and computer readable media for mobility robustness optimization in a conditional handover (CHO) with candidate secondary cell group(s) (SCG(s)) procedure. BACKGROUND

[0002] Certain abbreviations that may be found in the description and / or in the figures are herewith defined as follows: CHO Conditional Handover CPA Conditional PSCell Addition CPAC Conditional PSCell Addition or Change CPC Conditional PSCell Change MCG Master Cell Group MN Master Node MR-DC Multi-Radio Dual Connectivity MRO Mobility Robustness Optimization 0AM Operations Administration and Maintenance PCell Primary Cell PSCell Primary Secondary Cell RAN Radio Access Network RLF Radio Link Failure RRC Radio Resource Control SCell Secondary Cell SCG Secondary Cell Group SN Secondary Node UE User Equipment

[0003] Massive deployment of dense small cells for 5G network will enhance coverage and capacity, but on the other hand it would increase handover probability, potentially causing radio link failure (RLF). Therefore, mobility robustness optimization (MRO) solutions for mobility frameworks including conditional handover (CHO) with candidate secondary cell groups (SCG(s)) is under investigation in order to ensure reliable and stable communication during movements of mobile users. SUMMARY

[0004] A brief summary of example embodiments is provided below to provide basic understanding of some aspects of various embodiments. It should be noted that this summary is not intended to identify key features of essential elements or define scopes of the embodiments, and its sole purpose is to introduce some concepts in a simplified form as a preamble for a more detailed description provided below.

[0005] In a first aspect, an example embodiment of an apparatus is provided. The apparatus may comprise at least one processor and at least one memory. The at least one memory may store instructions that, when executed by the at least one processor, cause the apparatus at least to receive by a terminal device from a first network node a configuration message comprising at least one condition for a conditional handover and at least one condition for a cell addition or change, to evaluate whether the at least one condition for the conditional handover and the at least one condition for the cell addition or change are met, to detect a failure of a connection with a third network node before both of the at least one conditions are met, and to transmit a failure report indicating the connection failure taking place before both of the at least one conditions were met to the first network node.

[0006] In a second aspect, an example embodiment of an apparatus is provided. The apparatus may comprise at least one processor and at least one memory. The at least one memory may store instructions that, when executed by the at least one processor, cause the apparatus at least to transmit by a second network node to a first network node at least one condition for a cell addition or change, to receive from the first network node a failure report indicating a connection failure taking place between a terminal device and a third network node when at least the at least one condition for the cell addition or change was not met, and to carry out one of the following: transmitting the failure report to an operations administration and maintenance entity, or determining adaptation information for the at least one condition for the cell addition or change.

[0007] In a third aspect, an example embodiment of an apparatus is provided. The apparatus may comprise at least one processor and at least one memory. The at least one memory may store instructions that, when executed by the at least one processor, cause the apparatus at least to transmit by a first network node to a terminal device a configuration message comprising at least one condition for a conditional handover and at least one condition for a cell addition or change, to receive from the terminal device a failure report indicating a connection failure taking place between the terminal device and a third network node when at least one of the at least one condition for the conditional handover and the at least one condition for the cell addition or change was not met, and to carry out one of the following: transmitting the failure report to an operations administration and maintenance entity, transmitting the failure report to a second network node which determined the at least one condition for the cell addition or change in case the at least one condition for the cell addition or change was not met, or determining adaptation information for the at least one condition for the conditional handover in case the at least one condition for the conditional handover was not met.

[0008] In a fourth aspect, an example embodiment of an apparatus is provided. The apparatus may comprise at least one processor and at least one memory. The at least one memory may store instructions that, when executed by the at least one processor, cause the apparatus at least to receive by an operations administration and maintenance entity from a first network node or a second network device a failure report indicating a connection failure taking place between a terminal device and a third network node when at least one of at least one condition for a conditional handover and at least one condition for a cell addition or change was not met, to determine adaptation information for the at least one condition for the conditional handover or the at least one condition for the cell addition or change which was not met, and to transmit the adaptation information to (i) the first network node in case the adaptation information is determined for the at least one condition for the conditional handover which was not met, (ii) the second network node in case the adaptation information is determined for the at least one condition for the cell addition or change which was not met, or (iii) the first network node regardless of which of the at least one condition for the conditional handover and the at least one condition for the cell addition or change was not met, in case the failure report is received from the first network node.

[0009] Example embodiments of methods, apparatuses and computer readable media are also provided, which generally correspond to the above-described example embodiments and a repetitive description thereof is omitted here for convenience.

[0010] Other features and advantages of the example embodiments of the present disclosure will also be apparent from the following description of specific embodiments when read in conjunction with the accompanying drawings, which illustrate, by way of example, the principles of example embodiments of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Some example embodiments will now be described, by way of non-limiting examples, with reference to the accompanying drawings.

[0012] Fig. 1 is a schematic diagram illustrating an example communication network.

[0013] Fig 2 is a schematic message flow diagram illustrating an example process.

[0014] Fig. 3 is a schematic message flow diagram illustrating another example process.

[0015] Fig 4 is a schematic message flow diagram illustrating another example process.

[0016] Fig 5 is a schematic message flow diagram illustrating another example process.

[0017] Fig 6 is a schematic message flow diagram illustrating another example process.

[0018] Fig 7 is a schematic message flow diagram illustrating another example process.

[0019] Fig. 8 is a schematic flowchart illustrating an example method.

[0020] Fig 9 is a schematic flowchart illustrating another example method.

[0021] Fig 10 is a schematic flowchart illustrating another example method.

[0022] Fig. 11 is a schematic flowchart illustrating another example method.

[0023] Fig. 12 is a schematic flowchart illustrating another example method.

[0024] Fig 13 is a schematic flowchart illustrating another example method.

[0025] Fig 14 is a schematic flowchart illustrating another example method.

[0026] Fig 15 is a schematic flowchart illustrating another example method.

[0027] Fig. 16 is a schematic block diagram illustrating an example apparatus.

[0028] Fig 17 is a schematic block diagram illustrating another example apparatus.

[0029] Fig 18 is a schematic block diagram illustrating another example apparatus.

[0030] Fig 19 is a schematic block diagram illustrating another example apparatus.

[0031] Fig 20 is a schematic block diagram illustrating another example apparatus.

[0032] Fig 21 is a schematic block diagram illustrating another example apparatus.

[0033] Fig. 22 is a schematic block diagram illustrating another example apparatus.

[0034] Fig. 23 is a schematic block diagram illustrating another example apparatus.

[0035] Figs 24A, 24B and 24C are schematic block diagrams illustrating example devices.

[0036] Throughout the drawings, same or similar reference numbers indicate same or similar elements. A repetitive description on the same elements would be omitted. DETAILED DESCRIPTION

[0037] Herein below, some example embodiments are described in detail with reference to the accompanying drawings. The following description includes specific details for the purpose of providing a thorough understanding of various concepts. However, it will be apparent to those skilled in the art that these concepts may be practiced without these specific details. In some instances, well known circuits, techniques and components are shown in block diagram form to avoid obscuring the described concepts and features.

[0038] Fig 1 illustrates a schematic diagram of an example communication network 100 in which some example embodiments of the present disclosure can be implemented. The communication network 100 may be a wireless, mobile or cellular communication network. Referring to Fig. 1, the communication network 100 may comprise two domains: radio access network (RAN) 120 and core network (CN) 130. The RAN 120 may include a plurality of base stations (BSs), shown as BS 120Aand BS 120B, to provide network access for a plurality of user equipment (UEs) 110 (only one is shown). Each base station 120A, 120B may provide communication coverage for a particular geographic area, which is also known as cell. It would be appreciated that the term “cell” may refer to a coverage area of a base station or a subsystem of the base station for serving the coverage area, depending on the context in which the term is used.

[0039] The core network 130 may include numerous network functions (NFs) (not shown) to provide various functionalities. For instance, it can provide access controls to ensure that the UEs 110 are authenticated for the services they are using, route telephone calls over the public switched telephone network (PSTN), connect the UEs 110 to a data network e.g. the internet, and enable operators to charge for calls and data use. The core network 130 can also control the network by making handover happen as a UE moves from a cell coverage provided by a base station to another cell coverage provided by the same or a different base station. In some example embodiments, the core network 130 may be deployed on cloud, e.g. a public cloud, a private cloud or a hybrid cloud.

[0040] The UE 110 may be configured to operate in a Dual Connectivity (DC) mode. In the DC mode, the UE 110 is connected to two base stations, e.g. the first base station 120A and the second base station 120B as shown in Fig. 1. It is assumed that the first base station 120A acts as a master node (MN) for the UE 110 and the second base station 120B acts as a secondary node (SN) for the UE 110. The MN 120A has a radio resource control (RRC) connection with the UE 110 and provides both control plane (CP) and user plane (UP) connections to the core network 130. The SN 1208 provides additional resources to the UE 110, but it does not provide for the UE 110 a CP connection to the core network 130. The UE 110 can simultaneously receive and transmit data on a plurality of component carriers from serving cells of the MN 120 A and the SN 120B. The serving cells of the MN 120Amay be referred to as a master cell group (MCG), which includes a primary cell (PCell) 121 and optionally one or more secondary cells (SCells) 122. The PCell 121 is used to initiate an initial access of the UE 110 to the network 100, and it serves as a main point of connection for the UE 110. The UE 110 aggregates the PCell 121 and the one or more SCells 122 by carrier aggregation (CA). The serving cells of the SN 120B may be referred to as a secondary cell group (SCG), which includes a primary secondary cell (PSCell) 123 and optionally one or more secondary cells (SCells) 124. Similarly, the PSCell 123 is used to initiate an initial access under SCG, and it is aggregated with the one or more SCells 124 by carrier aggregation. The dual connectivity and carrier aggregation technologies enable the UE 110 to combine resources of multiple cells or carriers, thereby achieving higher data rate. In case of multi-radio dual-connectivity (MR-DC), one of the MN 120A and the SN 120B may be a 5G New Radio (NR) base station, and the other may be either an E-UTRAbase station or a NR base station. The UE 110 may also operate in the C A mode without dual connectivity.

[0041] When the UE 110 moves from one cell to another, a handover procedure may be executed to ensure reliable and stable communication between the UE 110 and the network. In a conditional handover (CHO) procedure, the UE 110 may evaluate certain execution conditions and decide to perform handover when the execution conditions are met. The UE 110 may be provided with a CHO with SN or CHO with candidate SCG configuration, which may include a CHO configuration (also referred to as MCG configuration) for PCell change, a conditional PSCell addition or change (CPAC) configuration (also referred to as SCG configuration) for PSCell addition or change, and associated execution conditions. The CPAC configuration may include for example a conditional PSCell addition (CPA) configuration and / or a conditional PSCell change (CPC) configuration. Upon receiving the configuration, the UE 110 may start evaluating the execution conditions for the candidate PCell and PSCell. In some cases, CHO in MR-DC may be limited to a scenario where the target MN can prepare a single target PSCell (under the control of an SN), and the execution conditions for the candidate PCell, PSCell are not tied to each other. The UE 110 can execute the PCell change or the PSCell addition or change independently when the associated execution condition is satisfied. In other words, the CPAC execution condition would not impact the CHO execution, and the CHO execution condition would not impact the CPAC execution.

[0042] In some cases, the CHO in MR-DC may be extended to a scenario where the target MN can prepare multiple candidate PSCells for the same candidate PCell. It improves usefulness of the CHO in MR-DC feature where a UE may need to access a different candidate PSCell when the CHO needs to be executed. In case there are multiple candidate PSCells associated with one candidate PCell, the CHO with candidate SCG(s) configuration provided from the network to the UE 110 may include multiple CHO and CPAC configurations for the same candidate PCell and different candidate PSCells, i.e. each one contains one CHO / MCG configuration for the same candidate PCell and one CPAC / SCG configuration for a different candidate PSCell, and associated execution conditions. The CHO and CPAC execution conditions associated with one CHO and CPAC configuration are tied to each other and will be evaluated in parallel at the UE 110. If one of the CHO and CPAC execution conditions is met but the other is not met, the UE 110 will continue to evaluate both CHO and CPAC execution conditions. In other words, the UE 110 will not perform PCell change and PSCell addition or change until both CHO and CPAC execution conditions are met. Therefore, the CHO and CPAC execution conditions should be set in a way that they will be in-line with each other, i.e., one condition does not necessarily block the other such that it will not prevent the UE from executing the handover unnecessarily.

[0043] In case the CHO and CPAC execution conditions are independent from each other, the network can adapt the CHO and CPAC execution conditions by looking at the failure information. For example, if the CHO execution fails due to wrong CHO execution condition configuration, the network can know from the failure information that what went wrong with the CHO execution condition, and adapt the CHO execution condition to reduce the failure. The CHO failure information would not indicate status of the CPAC execution condition because the CPAC execution condition does not impact the CHO execution. As another example, if the CPAC execution fails due to wrong CPAC execution condition configuration, the network can know from the failure information that what went wrong with the CPAC execution condition, and adapt the CPAC execution condition to reduce the failure. The CPAC failure information would not indicate status of the CHO execution condition because the CHO execution condition does not impact the CPAC execution.

[0044] In case UE is configured with the CHO and CPAC configuration containing CHO and CPAC execution conditions tied to each other, if one of the execution conditions is not configured properly, the CHO and CPAC execution may be delayed because, as discussed above, UE should execute CHO and CPAC only when both conditions are met. This delay may lead UE to drown under interference of the target PCell of target MCG or target PSCell of target SCG. If the CHO and CPAC execution is delayed long enough, the UE will experience a radio link failure on either the source master node link (also referred to as MCG link) or the source secondary node link (also referred to as SCG link). However, the network cannot identify which of the CHO and CPAC execution conditions is sub-optimal, wrong or improper because the UE performs the CHO and CPAC only when the CHO and CPAC execution conditions both are met. If one of the CHO and CPAC execution conditions is not configured properly, the entire CHO and CPAC execution would be delayed as the CHO and CPAC configuration cannot be executed partially. The delayed execution due to the unsatisfied execution condition may render the UE susceptible to interference from the target PCell or the target PSCell, resulting in an interruption and consequently a radio link failure (RLF) at the UE side. Currently, there is no mechanism to identify the cause of the RLF, i.e., whether the RLF is caused by the CHO execution condition or the CPAC execution condition, after the UE reestablish a radio connection with the network. For example, if an MCG RLF is caused by an improper CPAC execution condition, the RLF report contains only CHO relevant information, but the CPAC condition status is not known. If an SCG failure is caused by an improper CHO execution condition, the SCG failure information contains only CPAC relevant information, but the CHO condition status is not known. Therefore, it is not possible for the network to fix the problem when the CHO and CPAC configuration comprising the combined CHO and CPAC execution conditions is configured as it does not know which of the CHO and CPAC execution conditions caused the problem.

[0045] Example embodiments of the present disclosure provide mobility robustness optimization (MRO) solutions for the combined CHO and CPAC mobility. The MRO solutions can identify which of the CHO and CPAC execution conditions caused the mobility robustness issues, i.e., MCG failure or SCG failure, before the CHO and CPAC is successfully executed. In some example embodiments, the UE can log, in various reports depending on the scenario, which execution condition(s) was not fulfilled and leaded to the case specific problems so that the network can know from the UE reports if the failure is caused by the CHO execution condition, the CPAC execution, or neither of them (e.g., by coverage hole). Then the network can determine adaptation information for the problematic execution condition. The condition adaptation may be implemented in a centralized way e.g. at an operations administration and maintenance (0AM) entity, or in a distributed way e.g. at a base station which determined the problematic execution condition. Some example embodiments also propose new triggers for the failure report in the context of CHO and CPAC tied to each other and define UE behavior when the failure report is configured.

[0046] Fig. 2 illustrates an example process 200 for adaptation of combined CHO and CPAC execution conditions in a CHO and CPAC configuration.

[0047] As shown in Fig. 2, a source master node (S-MN) 120A may initiate a conditional handover preparation procedure for a UE 110 by transmitting at 210 a handover (HO) request message to one or more potential / candidate target master nodes (T-MNs) including a T-MN 120C. It is assumed that the UE 110 operates in the dual connectivity (DC) mode, connecting to the S-MN 120 A and a source secondary node (S-MN) 120B. The S-MN 120 A may determine one or more candidate T-MNs for the UE 110 based on measurement reports received from the UE 110 and send the handover request to the candidate T-MNs. In some example embodiments, the handover request may indicate the maximum number of conditional reconfigurations that the candidate T-MN 120C can prepare for the UE 110.

[0048] Upon receiving the handover request, the T-MN 120C may decide to prepare a CHO and CPAC configuration, also referred to as CHO with candidate SCG(s) configuration, for the UE 110 and transmit at 212 a SN addition request to one or more potential / candidate target secondary nodes (T-SNs) including the T-SN 120D. The SN addition request may include CHO related information e.g. the source MN identifier (ID) and the UE ID in the source MN to indicate that the SN addition preparation procedure is triggered in relation to a conditional handover and to enable the candidate SN to identify requests related to the same UE. The T-MN 120C may indicate one or more candidate PSCells recommended by the T-MN 120C via the latest measurement results for the T-SN 120D to choose and configure candidate SCG cell(s), and the maximum number of candidate PSCells that the T-SN 120D can prepare for the UE 110, in the SN addition request.

[0049] At 214, the T-SN 120D may respond to the T-MN 120C with a SN addition request acknowledge message. The SN addition request acknowledge message may include a list of PSCell(s) to prepare (considering the maximum number indicated by the T-MN 120C) and other SCG SCells for each prepared PSCell.

[0050] At 216, the T-MN 120C may determine a CHO and CPAC configuration including an MCG configuration (also referred to as CHO configuration) and an SCG configuration (also referred to as CPAC configuration) tied to each other. The MCG configuration is determined at the T-MN 120C and indicates a candidate PCell and optionally one or more MCG SCells prepared at the T-MN 120C. The SCG configuration is received from the T-SN 120D at 214 and indicates a candidate PSCell and optionally one or more SCG SCells prepared at the T-SN 120D. In some example embodiments, the T-MN 120C may determine multiple CHO and CPAC configurations each including a pair of the MCG / CHO configuration and the SCG / CPAC configuration. For example, the T-MN 120C may prepare multiple candidate PCells for the UE 110, and for each PCell, multiple PSCells may be prepared at the T-SN 120D and / or other potential T-SNs.

[0051] The T-MN 120C may also determine at 216 at least one CPAC execution condition (or CPAC condition for short) for each SCG configuration, or exactly the target PSCell in the SCG configuration. In some example embodiments, the T-MN 120C may determine a dual event (e.g., A3 and A5 events) execution condition for the SCG configuration, which means both events have to be simultaneously fulfilled in order to trigger the CPAC to the target PSCell.

[0052] Optionally, the T-MN 120C may also determine at 216 a failure report configuration for the UE 110, specifying contents and / or triggering criteria of a failure report. The failure report may be transmitted from the UE 110 in case the UE 110 encounters an MCG or SCG link failure before the CHO and CPAC is triggered, which will be described in detail below. In some example embodiments, the failure report configuration may be determined by the S-MN 120A or predefined at the UE 110 instead.

[0053] Then the T-MN 120C may transmit a handover request acknowledge message to the S-MN 120A at 218. The handover request acknowledge message may contain one or more CHO and CPAC configuration each including the MCG / CHO configuration, the SCG / CPAC configuration, and the CPAC execution condition for the SCG / CPAC configuration. The acknowledge message may also contain the failure report configuration determined at the T-MN 120C. In some example embodiments, the failure report configuration may be transmitted via a separate message to the S-MN 120A. It would be appreciated that the S-MN 120Amay receive the handover request acknowledge message from a plurality of potential / candidate T-MNs.

[0054] In response to the handover request acknowledge message, the S-MN 120A may determine at 220 at least one CHO execution condition (or CHO condition for short) for each MCG / CHO configuration, or exactly the target PCell indicated in the MCG configuration. In some example embodiments, the S-MN 120A may determine a dual event (e.g., A3 and A5 events) execution condition for the MCG configuration, which means both events have to be simultaneously fulfilled in order to trigger the CHO to the target PCell. It would be appreciated that the CHO execution condition and the corresponding CPAC execution condition are determined in a way that they will be in-line with each other, i.e., one condition does not necessarily block the other.

[0055] In some example embodiments, if the T-MN 120C does not determine the failure report configuration at 216, the S-MN 120A may determine the failure report configuration at 220. In some other example embodiments, the failure report configuration may be pre-defined at the UE 110, neither the T-MN 120C and the S-MN 120A needs to determine the failure report configuration for the UE 110. In some other example embodiments, the failure report configuration may be partly determined at the T-MN 120C and / or the S-MN 120A, and a remaining part may be pre-defined at the UE 110.

[0056] At 222, the S-MN 120A may transmit an RRC reconfiguration message containing one or more CHO and CPAC configurations and optionally the failure report configuration to the UE 110. The one or more CHO and CPAC configurations each may include the MCG / CHO configuration, the SCG / CPAC configuration, at least one CHO execution condition, and at least one CPAC execution condition. As discussed above, the CHO execution condition(s) and the CPAC execution condition(s) contained in each CHO and CPAC configuration are tied to each other so that they both have to be satisfied in order to trigger execution of the CHO and CPAC based on the CHO and CPAC configuration. Here it is assumed that the UE 110 is not provided and configured with a CHO-only configuration or a CHO with candidate SCG configuration comprising independent CHO and CPAC execution conditions. If the UE 110 is configured with the CHO-only configuration or the CHO with candidate SCG configuration comprising independent CHO and CPAC execution conditions and the CHO execution condition used for the CHO and CPAC configuration is also used for the CHO-only configuration or the CHO with candidate SCG configuration, when the CHO execution condition is fulfilled and the corresponding CPAC execution condition is not fulfilled, the UE 110 will trigger the PCell change based on the CHO-only configuration or the CHO with candidate SCG configuration, not waiting for the CPAC execution condition being fulfilled.

[0057] At 224, the UE 110 may store the received configurations and respond to the S-MN 120 A with an RRC reconfiguration complete message.

[0058] After receiving the CHO and CPAC configuration, the UE 110 may start evaluating whether the CHO execution condition and the CPAC execution condition are met at 226. For example, the UE 110 may evaluate the CHO execution condition based on measurements of the target / candidate PCell and optionally measurements of the source / serving PCell, and evaluate the CPAC execution condition based on measurements of the target / candidate PSCell and optionally measurements of the source / serving PSCell. If the UE 110 determines that one of the CHO and CPAC execution conditions is fulfilled and the other is not yet, as mentioned above, the UE 110 would not perform the CHO and CPAC, and the CHO and CPAC execution is delayed due to the unfulfilled condition.

[0059] At 228, the UE 110 may experience / detect an interruption of the radio connection with the S-MN 120A. In response to the interruption, the UE 110 may start a radio link failure (RLF) timer T310 for the S-MN link. The interruption may be caused by link quality deterioration between the UE 110 and the S-MN 120A and / or by interference of the T-MN 120C, as the UE 110 moves away from the S-MN 120A. In some other example embodiments, one of the CHO and CPAC execution conditions may be fulfilled first, and then the UE 110 may experience the interruption. In some other example embodiments, the UE 110 may experience the interruption first, and then one of the CHO and CPAC execution conditions may be met. In other words, it is possible that when the interruption takes place, neither the CHO execution condition nor the CPAC execution condition is fulfilled.

[0060] If neither the S-MN link recovers nor the CHO and CPAC execution conditions both are fulfilled to trigger execution of the CHO and CPAC before the RLF timer T310 for the S-MN link expires, the UE 110 may declare an RLF of the S-MN link at 230. In some example embodiments, the UE 110 may also declare the RLF of the S-MN link due to other reasons. Three scenarios of the S-MN RLF are listed below: - Case 1: S-MN (MCG) RLF when the CHO and CPAC configuration is configured: • Case 1A: When the CHO execution condition is met but the CPAC execution condition is not met, the UE experiences RLF with the S-MN due to interference of the T-MN; • Case IB: When the CPAC execution condition is met but the CHO execution condition is not met, the UE experiences RLF with the S-MN due to low link quality (e.g. reference signal received power, RSRP) with the S-MN (e.g. S-MN coverage hole); • Case IC: When neither the CHO execution condition nor the CPAC execution condition is met, the UE experiences RLF with the S-MN due to interference of the T-MN and / or low link quality with the S-MN.

[0061] After declaring the RLF, the UE 110 may trigger a failure report if the criteria for triggering the failure report is satisfied. As discussed above, the criteria for triggering the failure report may be received from the S-MN 120A at 222 or predefined at the UE 110. In some example embodiments, the criteria for triggering the failure report may include that at least one of the CHO execution condition and the CPAC execution condition is not met at the time of RLF. In some other example embodiments, the criteria for triggering the failure report may include that one of the CHO and CPAC execution conditions is not met and the other is met at the time of RLF. In the example shown in Fig. 2, it is assumed that the failure report triggering criterion is satisfied, and the UE 110 triggers the failure report at 232.

[0062] In some example embodiments, if an execution condition is met according to the relevant measurements but a time-to-trigger (TTT) timer of the condition is still running, the UE 110 would not trigger the CHO and CPAC execution. Therefore, reference of a condition being not met covers both a scenario where the condition is not met and the TTT timer associated with the condition is not running (i.e., the timer value is zero), and a scenario where the condition is met according to the measurements but the TTT timer associated with the condition is still running.

[0063] The UE 110 may create the failure report and log relevant failure information in the report at 232. In some example embodiments, the UE 110 may log in the failure report an identifier (ID) of the CHO and CPAC configuration which has at least one execution condition not met yet, and a cause of not triggering the CHO and CPAC execution based on the CHO and CPAC configuration. For example, the cause may indicate which of the CHO execution condition and the CPAC execution condition was / were not met at the time of RLF, i.e. the problematic condition(s) causing delay of the CHO and CPAC execution and eventually the RLF. Alternatively or additionally, the cause may also indicate which one of the CHO execution condition and the CPAC execution condition was met at the time of RLF, from which it can be inferred that the other condition was not met. For example, in Case 1 A, the cause may indicate the CHO execution condition was met but the CPAC execution condition was not met; in Case IB, the cause may indicate the CPAC execution condition was met but the CHO execution condition was not met; in Case IC, the cause may indicate neither the CHO execution condition nor the CPAC execution condition was met. In some example embodiments, if the CHO execution condition and the CPAC execution condition each is configured as a dual event condition, the UE 110 may use four information elements (IEs) to indicate whether the two dual events were met or not.

[0064] In some example embodiments, the UE 110 may log in the failure report relevant information that may be used to adapt the problematic condition so as to eliminate or mitigate the RLE For example, the UE 110 may log one or more of the following: • the CHO execution condition or the CPAC execution condition which was not met at the time of RLF, e.g., the event threshold or offset values of the unmet condition, • information of the target cell (PCell or PSCell) relating to the unmet condition, e.g., physical cell identifier (PCI) and frequency of the target cell, • N last measurements of the target cell before the RLF, where N is a positive integer, • information of a source cell (PCell or PSCell) relating to the unmet condition, e.g., PCI and frequency of the source cell, • N last measurements of the source cell before the RLF, or • an indication indicating that the TTT timer of the CHO or CPAC execution condition which was not met was running at the time of RLF. It would be appreciated the above information are described as example contents of the failure report, but the failure report is not limited in any way to such examples. The UE 110 may generate the failure report according to the failure report configuration predefined at the UE 110 or received from the S-MN 120A at 222.

[0065] In response to the RLF, the UE 110 may initiate an RRC connection re-establishment procedure and connect to a suitable cell at 234. In the example shown in Fig. 2, it is assumed that the UE 110 connects to the T-MN 120C, but it would be appreciated that the UE 110 may connect to any other suitable cell and base station through the cell re-selection procedure. For example, the UE 110 may connect to the S-MN 120A, the S-SN 120B (in Fig. 1), the T-SN 120D, or any base station that is not involved in the conditional handover procedure. Therefore, some operations of the T-MN 120C described below may be performed at a different base station to which the UE 110 connects after the RLE

[0066] At 236, the UE 110 may send the failure report to the T-MN 120C (or any other base station now the UE 110 connects to), indicating the RLF taking place before both the CHO execution condition and the CPAC execution condition were met, i.e., when at least one of the CHO execution condition and the CPAC execution condition was not met. In some example embodiments, the UE 110 may indicate availability of the failure report to the T-MN 120C in an RRC complete message, e.g. RRCReconfigurationComplete, RRCReestablishmentComplete, RRCSetupComplete, or RRCResumeComplete messages, and then the T-MN 120C may fetch the failure report by a UE information request procedure. In some other example embodiments, the T-MN 120C may blindly fetch the failure report from the UE 110, or the UE 110 may directly transmit the failure report to the T-MN 120C, after the UE 110 successfully connects to the T-MN 120C. The contents of the failure report have been described above and a repetitive description thereof is omitted here for simplicity and convenience.

[0067] In some example embodiments, the T-MN 120C may transmit the received failure report to the 0AM 140 at 238. Before transmitting the failure report to the 0AM 140, the T-MN 120C may modify the failure report e.g. by adding new information elements and / or removing unnecessary information elements if needed. In some example embodiments, the T-MN 120C may transmit the failure report in a transparent container to the 0AM 140, and the T-MN 120C may not know the contents of the failure report.

[0068] The 0AM 140 may collect a certain number of the failure reports relating to the CHO and CPAC configuration and analyze statistics of the RLFs to determine whether the RLFs were caused by the unmet execution condition(s) or by other factors. If the RLFs were caused by the unmet execution condition(s), the 0AM 140 may determine adaptation information for the unmet / problematic execution condition(s) to eliminate or reduce the RLFs. For instance, the 0AM 140 may decide to adjust parameters e.g. the event threshold and / or offset value(s) of the problematic execution condition(s) so that the execution condition(s) can be fulfilled earlier, e.g. before expiry of the T310 timer, thereby eliminating or reducing the RLE. The 0AM 140 may determine the adaptation information for the unmet / problematic execution condition(s) based on the failure reports, e.g. the N last measurements of the target cell and optionally the N last measurements of the source cell indicated in the failure report. The adaptation information may comprise one or more new parameter values for the problematic execution condition(s), or one or more delta amounts for one or more parameters of the problematic execution condition(s). In some example embodiments, the 0AM 140 may execute a machine learning model or algorithm to determine the adaptation information for the problematic execution condition(s). The machine learning model may receive information elements in the failure reports as input, and provide the adaptation information as output.

[0069] At 240, the 0AM 140 may transmit the adaptation information for the unmet execution condition(s) to the base station from which the failure report was received, e.g. the T-MN 120C in the example shown in Fig. 2. The 0AM 140 may indicate to the T-MN 120C whether the adaptation information is for the CHO execution condition or the CPAC execution condition.

[0070] If the adaptation information is for the CPAC execution condition determined at the T-MN 120C, the T-MN 120C may adapt the CPAC execution condition based on the adaptation information at 242. For example, the T-MN 120C may determine a new CPAC execution condition taking into account the adaptation information when it receives a new handover request from the S-MN 120A.

[0071] If the adaptation information is for the CHO execution condition determined at the S-MN 120A, the T-MN 120C may send the adaptation information to the S-MN 120A at 244. In some example embodiments, the 0AM 140 may directly transmit the adaptation information for the CHO execution condition to the S-MN 120A at 246. The 0AM 140 can know from the CHO and CPAC configuration identifier indicated in the failure report that the problematic execution condition was determined by which base station. If the adaptation information is determined for the CHO execution condition, the 0AM 140 may transmit the adaptation information to the S-MN 120A at 246. If the adaptation information is determined for the CPAC execution condition, the 0AM 140 may transmit the adaptation information to the T-MN 120C at 240. It can reduce the signaling overhead of the network.

[0072] At 248, the S-MN^ 120 / X. may adapt the CHO execution condition based on the adaptation information. For example, the S-MN 120A may determine a new CHO execution condition taking into account the adaptation information when it receives a new CHO and CPAC configuration from the T-MN 120C.

[0073] In some example embodiments, if the 0AM 140 transmits the adaptation information to the base station from which the failure report is received but the base station is not involved in the CHO and CPAC procedure, the base station may forward the adaptation information to the S-MN 120A or the T-MN 120C. For example, the adaptation information may contain an information element indicating a destination of the adaptation information.

[0074] In the process 200, the UE 110 reports the failure information to the T-MN 120C (or any base station the UE 110 connects to after the RLF), and then the T-MN 120C transmits the failure information to the 0AM 140. In some example embodiments, the T-MN 120C may send the failure information to the S-MN 120A. The S-MN 120A may transmit the failure information to the 0AM 140, or handle the failure information in other ways. An example of such a process is illustrated in Fig. 3.

[0075] Referring to Fig. 3, the process 300 may also include the steps 210-236 described above with respect to Fig. 2, and a repetitive description of the steps 210-236 is omitted here. After receiving the failure report from the UE 110 at 236, the T-MN 120C (or any base station now the UE 110 connects to) may transmit at 310 the failure report to the S-MN 120A, i.e. the source master node of the UE 110 before the RLF. The T-MN 120C (or any base station now the UE 110 connects to) can determine the S-MN 120A based on the identifier of the CHO and CPAC configuration indicated in the failure report.

[0076] At 312, the S-MN 120A may transmit the received failure report to the 0AM 140. Before transmitting the failure report to the 0AM 140, the S-MN 120A may modify the failure report e.g. by adding new information elements and / or removing unnecessary information elements if needed.

[0077] The 0AM 140 may collect a certain number of the failure reports relating to the CHO and CPAC configuration and analyze statistics of the RLFs to determine whether the RLFs were caused by the unmet execution condition or by other factors. If the RLFs were caused by the unmet execution condition, the 0AM 140 may determine adaptation information for the unmet / problematic execution condition to eliminate or reduce the RLFs. For instance, the 0AM 140 may decide to adjust parameters e.g. the event threshold and / or offset value(s) of the problematic execution condition so that the execution condition can be fulfilled earlier, e.g. before expiry of the T310 timer, thereby eliminating or reducing the RLF.

[0078] At 314, the 0AM 140 may transmit the adaptation information for the unmet execution condition to the S-MN 120A, i.e., the base station from which the failure report was received. The 0AM 140 may indicate to the S-MN 120A whether the adaptation information is for the CHO execution condition and / or the CPAC execution condition.

[0079] If the adaptation information is for the CHO execution condition determined at the S-MN 120A, the S-MN 120A may adapt the CHO execution condition based on the adaptation information at 316. For example, the S-MN 120A may determine a new CHO execution condition taking into account the adaptation information when it receives a CHO and CPAC configuration from the T-MN 120C.

[0080] If the adaptation information is for the CPAC execution condition determined at the T-MN 120C, the S-MN 120A may send the adaptation information to the T-MN 120C at 318. In some example embodiments, the 0AM 140 may directly transmit the adaptation information for the CPAC execution condition to the T-MN 120C at 320. The 0AM 140 can know from the CHO and CPAC configuration identifier indicated in the failure report that the problematic execution condition was determined by which base station. If the adaptation information is determined for the CHO execution condition, the 0AM 140 may transmit the adaptation information to the S-MN 120Aat 314. If the adaptation information is determined for the CPAC execution condition, the 0AM 140 may transmit the adaptation information to the T-MN 120C at 320. It can reduce the signaling overhead of the network.

[0081] At 322, the T-MN 120C may adapt the CPAC execution condition based on the adaptation information. For example, the T-MN 120C may determine a new CPAC execution condition taking into account the adaptation information when it receives a new handover request from the S-MN 120A.

[0082] In the above-described processes 200 and 300, the T-MN 120C (or any base station the UE 110 connects to after the RLF) transmits the failure report received from the UE 110 to the 0AM 140 or to the S-MN 120A. In some example embodiments, the T-MN 120C may selectively transmit the failure report indicating the CPAC execution condition being unmet to the 0AM 140, and selectively transmit the failure report indicating the CHO execution condition being unmet to the S-MN 120A. Then the S-MN 120A may transit the failure report indicating the CHO execution condition being unmet to the 0AM 140. The 0AM 140 may transmit the adaptation information for the CHO execution condition to the S-MN 120A and the adaptation information for the CPAC execution condition to the T-MN 120C.

[0083] In the processes 200 and 300, the execution condition adaptation is performed in a centralized manner, i.e. the 0AM 140 acts as the entity which collects the failure reports to derive the statistics and adapt the condition parameters. In some other example embodiments, the execution condition adaptation may be performed in a distributed manner, i.e. at the base stations where the execution conditions were determined. Hence the signaling from / to the 0AM may be omitted, and the work load is distributed to a plurality of network nodes. An example of such a process is illustrated in Fig. 4.

[0084] Referring to Fig. 4, the process 400 may also include the steps 210-236 described above with respect to Fig. 2, and a repetitive description of the steps 210-236 is omitted here. After receiving the failure report from the UE 110 at 236, if the failure report indicates that the CPAC execution condition was not met, the T-MN 120C may determine adaptation information for the CPAC execution condition at 410. In some example embodiments, the T-MN 120C may collect a certain number of the failure reports from a plurality of UEs and analyze statistics of the RLFs to determine whether the RLFs were caused by the unmet CPAC execution condition or by other factors. If the RLFs were caused by the unmet CPAC execution condition, the T-MN 120C may determine adaptation information for the CPAC execution condition to eliminate or reduce the RLFs. For instance, the T-MN 120C may decide to adjust parameters e.g. the event threshold and / or offset value(s) of the problematic execution condition so that the execution condition can be fulfilled earlier, e.g. before expiry of the T310 timer, thereby eliminating or reducing the RLF. The T-MN 120C may determine the adaptation information for the CPAC execution condition based on the failure reports, e.g. the N last measurements of the target PSCell and optionally the N last measurements of the source PSCell indicated in the failure report. In some example embodiments, the T-MN 120C may execute a machine learning model or algorithm to determine the adaptation information for the CPAC execution condition. The adaptation information may comprise one or more new parameter values for the problematic execution condition, or one or more delta amounts for one or more parameters of the problematic execution condition.

[0085] At 412, the T-MN 120C may adapt the CPAC execution condition based on the determined adaptation information. For example, the T-MN 120C may determine a new CPAC execution condition taking into account the adaptation information when it receives a new handover request from the S-MN 120A.

[0086] If the failure report indicates that the CHO execution condition was not met, the T-MN 120C can determine from the identifier of the CHO and CPAC configuration indicated in the failure report that the unmet CHO execution condition was determined by the S-MN 120A because the CHO and CPAC configuration was sent from the T-MN 120C to the S-MN 120A at 218. Then the T-MN 120C may transmit the failure report to the S-MN 120A at 414.

[0087] In response to the failure report indicating that the CHO execution condition was not met, the S-MN 120 A may determine adaptation information for the CHO execution condition at 416. In some example embodiments, the S-MN 120A may collect a certain number of the failure reports relating to the CHO and CPAC configuration and analyze statistics of the RLFs to determine whether the RLFs were caused by the unmet CHO execution condition or by other factors. If the RLFs were caused by the unmet CHO execution condition, the S-MN 120A may determine adaptation information e.g. one or more new parameter values or delta amounts for the CHO execution condition to make the CHO execution condition be fulfilled earlier, e.g. before expiry of the T310 timer, thereby eliminating or reducing the RLE The S-MN 120A may determine the adaptation information for the CHO execution condition based on the failure reports, e.g. the N last measurements of the target PCell and optionally the N last measurements of the source PCell indicated in the failure report.

[0088] At 418, the S-MN 120A may adapt the CHO execution condition based on the determined adaptation information. For example, the S-MN 120A may determine a new CHO execution condition taking into account the adaptation information when it receives a new CHO and CPAC configuration from the T-MN 120C.

[0089] In some example embodiments, if the UE 110 connects and transmits the failure report to a based station that is not involved in the CHO and CPAC procedure, the base station may transmit the failure report to the T-MN 120C if the failure report indicates that the CPAC execution condition was not met or to the S-MN 120A if the failure report indicates that the CHO execution condition was not met. Then the T-MN 120C or the S-MN 120A can determine and apply the adaptation information for the unmet execution condition.

[0090] In the above-described example embodiments, the UE 110 experiences an RLF with the MCG connection before the CHO and CPAC execution is trigger, i.e. before both the CHO and CPAC execution conditions are met. In some other example embodiments, the UE 110 may experience an RLF with the SCG connection before the CHO and CPAC execution is trigger. An example process involving the SCG failure is shown in Fig. 5.

[0091] Referring to Fig. 5, the process 500 may also include the steps 210-226 described above with respect to Fig. 2, and a repetitive description of the steps 210-226 is omitted here. At 510, the UE 110 may experience / detect an interruption of the radio connection with the S-SN 120B (not shown). As discussed above, the UE 110 may experience the S-SN link interruption before or after one of the CHO and CPAC execution conditions is met. In response to the interruption, the UE 110 may start a radio link failure (RLF) timer T310 for the S-SN link. The interruption may be caused by link quality (e.g., reference signal received power, RSRP) deterioration between the UE 110 and the S-SN 120B and / or by interference of the T-SN 120D, as the UE 110 moves away from the S-SN 120B. In some example embodiments, the UE 110 may experience the interruption first, and then one of the CHO and CPAC execution conditions is met. In other words, when the interruption takes place, neither the CHO execution condition nor the CPAC execution condition is fulfilled.

[0092] If neither the S-SN link recovers nor the CHO and CPAC execution conditions both are fulfilled to trigger execution of the CHO and CPAC before the RLF timer T310 for the S-SN link expires, the UE 110 may declare an SCG failure at 512. In some example embodiments, the UE 110 may also declare the SCG failure due to other reasons, e.g. network condition changes affecting the PSCell’s performance. Three scenarios of the SCG failure are listed below: - Case 2: SCG (S-SN) failure when the CHO and CPAC configuration is configured: • Case 2A: When the CPAC execution condition is met but the CHO execution condition is not met, the UE experiences failure with the S-SN due to interference of the T-SN; • Case 2B: When the CHO execution condition is met but the CPAC execution condition is not met, the UE experiences failure with the S-SN due to low link quality (e.g. reference signal received power, RSRP) with the S-SN (e.g. S-SN coverage hole); • Case 2C: When neither the CHO execution condition nor the CPAC execution condition is met, the UE experiences failure with the S-SN due to interference of the T-SN and low link quality with the S-SN.

[0093] In response to the SCG failure, the UE 110 may trigger a failure report if the criteria for triggering the failure report is satisfied. As discussed above, the criteria for triggering the failure report may be received from the S-MN 120A at 222 or predefined at the UE 110. In some example embodiments, the criteria for triggering the failure report may include that at least one of the CHO execution condition and the CPAC execution condition is not met at the time of SCG failure. In the example shown in Fig. 5, it is assumed that at least one of the CHO and CPAC execution conditions is not met at the time of SCG failure. Therefore, the failure report triggering criterion is satisfied, and the UE 110 triggers the failure report at 514.

[0094] The UE 110 may create the failure report and log relevant failure information in the report at 514. In some example embodiments, the UE 110 may log in the failure report an identifier (ID) of the CHO and CPAC configuration which has at least one execution condition not met yet, and a cause of not triggering the CHO and CPAC execution based on the CHO and CPAC configuration. For example, the cause may indicate which of the CHO execution condition and the CPAC execution condition was / were not met at the time of SCG failure, i.e. the problematic execution condition(s) causing delay of the CHO and CPAC execution and eventually the SCG failure. Alternatively or additionally, the cause may indicate which one of the CHO execution condition and the CPAC execution condition was met at the time of SCG failure, from which it can be inferred that the other condition was not met. For example, in Case 2A, the cause may indicate the CPAC execution condition was met but the CHO execution condition was not met; in Case 2B, the cause may indicate the CHO execution condition was met but the CPAC execution condition was not met; and in Case 2C, the cause may indicate neither the CHO execution condition nor the CPAC execution condition was met. In some example embodiments, if the CHO execution condition and the CPAC execution condition each is configured as a dual event condition, the UE 110 may use four information elements (IEs) to indicate whether the two dual events were met or not.

[0095] In some example embodiments, the UE 110 may log in the failure report relevant information that may be used to adapt the problematic condition so as to eliminate or mitigate the SCG failure. For example, the UE 110 may log one or more of the following: • the CHO execution condition or the CPAC execution condition which was not met at the time of SCG failure, e.g. the event threshold or offset values of the unmet condition, • information of the target cell (PCell or PSCell) relating to the unmet condition(s), e.g. physical cell identifier (PCI) and frequency of the target cell, • N last measurements of the target cell before the SCG failure, where N is a positive integer, • information of a source cell (PCell or PSCell) relating to the unmet condition(s), e.g. PCI and frequency of the source cell, • N last measurements of the source cell before the SCG failure, or • an indication indicating that the TTT timer of the CHO or CPAC execution condition which was not met was running at the time of SCG failure. It would be appreciated the above information are described as example contents of the failure report, but the failure report is not limited in any way to such examples. The UE 110 may generate the failure report according to the failure report configuration predefined at the UE 110 or received from the S-MN 120A at 222.

[0096] At 516, the UE 110 may transmit the failure report to the S-MN 120A, indicating the SCG failure taking place before both the CHO execution condition and the CPAC execution condition both were met, i.e., at least one of the CHO execution condition and the CPAC execution condition was not met at the time of the SCG failure. It is worth noting that in case of SCG failure, the UE 110 still has the radio connection with the S-MN 120A and hence it does not need to initiate the RRC connection re-establishment procedure. In some example embodiments, the UE 110 may indicate availability of the failure report to the S-MN 120A first, and then the S-MN 120A may fetch the failure report by a UE information request procedure. In some other example embodiments, the UE 110 may directly transmit the failure report to the S-MN 120A. The contents of the failure report have been described above and a repetitive description thereof is omitted here for simplicity and convenience.

[0097] In some example embodiments, the S-MN 120 A may transmit the received failure report to the 0AM 140 at 518. Before transmitting the failure report to the 0AM 140, the S-MN 120A may modify the failure report e.g. by adding new information elements and / or removing unnecessary information elements if needed. In some example embodiments, the S-MN 120A may transmit the failure report in a transparent container to the 0AM 140, and the S-MN 120A may not know the contents of the failure report.

[0098] The 0AM 140 may collect a certain number of the failure reports relating to the CHO and CPAC configuration and analyze statistics of the SCG failures to determine whether the SCG failures were caused by the unmet execution condition(s) or by other factors. If the SCG failures were caused by the unmet execution condition(s), the 0AM 140 may determine adaptation information for the unmet / problematic execution condition(s) to eliminate or reduce the SCG failures. For instance, the 0AM 140 may decide to adjust parameters e.g. the event threshold and / or offset value(s) of the problematic execution condition(s) so that the execution condition(s) can be fulfilled earlier, e.g. before expiry of the T310 timer, thereby eliminating or reducing the SCG failure. The 0AM 140 may determine the adaptation information for the unmet / problematic execution condition(s) based on the failure reports, e.g. the N last measurements of the target cell and optionally the N last measurements of the source cell indicated in the failure report. The adaptation information may comprise one or more new parameter values for the problematic execution condition(s), or one or more delta amounts for one or more parameters of the problematic execution condition(s). In some example embodiments, the 0AM 140 may execute a machine learning model or algorithm to determine the adaptation information for the problematic execution condition(s). The machine learning model may receive information elements in the failure reports as input, and provide the adaptation information as output.

[0099] At 520, the 0AM 140 may transmit the adaptation information for the unmet execution condition to the S-MN 120A. The 0AM 140 may indicate to the S-MN 120A whether the adaptation information is for the CHO execution condition and / or the CPAC execution condition.

[00100] Ifthe adaptation information is for the CHO execution condition determined at the S-MN 120A, the S-MN 120A may adapt the CHO execution condition based on the adaptation information at 522. For example, the S-MN 120A may determine a new CHO execution condition taking into account the adaptation information when it receives a new CHO and CPAC configuration from the T-MN 120C.

[00101] If the adaptation information is for the CPAC execution condition determined at the T-MN 120C, the S-MN 120A may transmit the adaptation information to the T-MN 120C at 524. In some example embodiments, the 0AM 140 may directly transmit the adaptation information for the CPAC execution condition to the T-MN 120C at 526. The 0AM 140 can know from the failure report that the problematic execution condition was determined by which base station. If the SCG failure is caused by the CHO execution condition, the 0AM 140 may transmit the adaptation information for the CHO execution condition to the S-MN 120A at 520. If the SCG failure is caused by the CPAC execution condition, the 0AM 140 may transmit the adaptation information for the CPAC execution condition to the T-MN 120C at 526. It can reduce the signaling overhead of the network.

[00102] At 528, the T-MN 120C may adapt the CPAC execution condition based on the adaptation information. For example, the T-MN 120C may determine a new CPAC execution condition taking into account the adaptation information when it receives a new handover request from the S-MN 120A.

[00103] In the process 500, the UE 110 reports the SCG failure information to the S-MN 120A, and the S-MN 120A forwards the SCG failure information to the 0AM 140. In some example embodiments, the S-MN 120A may send the failure information to the T-MN 120C. The T-MN 120C may transmit the failure information to the 0AM 140, or handle the failure information in other ways. An example of such a process is illustrated in Fig. 6.

[00104] Referring to Fig. 6, the process 600 may also include the steps 210-226, 510-516 described above with respect to Fig. 2 and Fig. 5, and a repetitive description of the steps 210-226, 510-516 is omitted here. After receiving the failure report from the UE 110 at 516, if the failure report indicates the CPAC execution condition was not met at the time of the SCG failure, the S-MN 120Amay transmit at 610 the failure report to the T-MN 120C which determined the CPAC execution condition. If the failure report indicates the CHO execution condition was not met at the time of the SCG failure, the S-MN 120 A may transmit the failure report to the 0AM 140 by the step 518 discussed above with respect to Fig. 5. If neither the CHO execution condition nor the CPAC execution condition was met, the S-MN 120A may transmit a part of the failure report relating to the CHO execution to the 0AM 140 and transmit a part of the failure report relating to the CPAC execution to the T-MN 120C.

[00105] In some example embodiments, the T-MN 120C may transmit the failure report to the 0AM 140 at 612. Before transmitting the failure report to the 0AM 140, the T-MN 120C may modify the failure report e.g. by adding new information elements and / or removing unnecessary information elements if needed. For example, the T-MN 120C may add information which helps to determine a proper CPAC execution condition into the failure report.

[00106] In some example embodiments, the S-MN 120A may transmit the failure report directly to the 0 AM 140 at 614 if the failure report indicates the CPAC execution condition was not met. It can reduce the overall signaling overhead of the network because the S-MN 120A does not need to transmit the failure report to the T-MN 120C.

[00107] The 0AM 140 may collect a certain number of the failure reports relating to the CHO and CPAC configuration and analyze statistics of the SCG failures to determine whether the SCG failures were caused by the unmet CPAC execution condition or by other factors. If the SCG failures were caused by the unmet CPAC execution condition, the 0AM 140 may determine adaptation information for the CPAC execution condition to eliminate or reduce the SCG failures. For instance, the 0AM 140 may decide to adjust parameters e.g. the event threshold and / or offset value(s) of the CPAC execution condition so that the CPAC execution condition can be fulfilled earlier, e.g. before expiry of the T310 timer, thereby eliminating or reducing the SCG failures. The 0AM 140 may determine the adaptation information for the CPAC execution condition based on the failure reports, e.g. the N last measurements of the target PSCell and optionally the N last measurements of the source PSCell indicated in the failure report. The adaptation information may comprise one or more new parameter values for the CPAC execution condition, or one or more delta amounts for one or more parameters of the CPAC execution condition. In some example embodiments, the 0AM 140 may execute a machine learning model or algorithm to determine the adaptation information for the CPAC execution condition.

[00108] At 616, the 0AM 140 may transmit the adaptation information for the CPAC execution condition to the T-MN 120C.

[00109] The T-MN 120C may adapt the CPAC execution condition based on the received adaptation information at 618. For example, the T-MN 120C may determine a new CPAC execution condition taking into account the adaptation information when it receives a new handover request from the S-MN 120A.

[00110] In the processes 500 and 600, the UE 110 reports the failure information to the S-MN 120A, and the S-MN 120A transmits the failure information to the 0AM 140 directly or via the T-MN 120C. Then the 0AM 140 determines the adaptation information for the unmet execution condition. In other words, the execution condition adaptation is performed in a centralized manner. In some other example embodiments, the execution condition adaptation may be performed in a distributed manner, i.e. at the base stations where the execution conditions were determined. Hence the signaling from / to the 0AM 140 may be omitted, and the work load is distributed to a plurality of network nodes. An example of such a process is illustrated in Fig. 7.

[00111] Referring to Fig. 7, the process 700 may also include the steps 210-226, 510-516 described above with respect to Fig. 2 and Fig. 5, and a repetitive description of the steps 210-226, 510-516 is omitted here. After receiving the SCG failure report from the UE 110 at 516, if the failure report indicates that the CHO execution condition was not met, the S-MN 120Amay determine adaptation information for the CHO execution condition at 710. In some example embodiments, the S-MN 120 A may collect a certain number of the failure reports from a plurality of UEs and analyze statistics of the SCG failures to determine whether the SCG failures were caused by the unmet CHO execution condition or by other factors. If the SCG failures were caused by the unmet CHO execution condition, the S-MN 120A may determine adaptation information for the CHO execution condition to eliminate or reduce the SCG failures. For instance, the S-MN 120A may decide to adjust parameters e.g. the event threshold and / or offset value(s) of the CHO execution condition so that the CHO execution condition can be fulfilled earlier, e.g. before expiry of the T310 timer, thereby eliminating or reducing the SCG failures. The S-MN 120A may determine the adaptation information for the CHO execution condition based on the failure reports, e.g. the N last measurements of the target PCell and optionally the N last measurements of the source PCell indicated in the failure report. In some example embodiments, the S-MN 120A may execute a machine learning model or algorithm to determine the adaptation information for the CHO execution condition. The adaptation information may comprise one or more new parameter values for the CHO execution condition, or one or more delta amounts for one or more parameters of the CHO execution condition.

[00112] At 712, the S-MbI 120.A. may adapt the CHO execution condition based on the determined adaptation information. For example, the S-MN 120A may determine a new CHO execution condition taking into account the adaptation information when it receives a new CHO and CPAC configuration from the T-MN 120C.

[00113] If the failure report received from the UE 110 indicates that the CPAC execution condition was not met, the S-MN 120Acan determine from the CHO and CPAC configuration identifier indicated in the failure report that the unmet CPAC execution condition was determined by the T-MN 120C. Then the S-MN 120A may transmit the failure report to the T-MN 120C at 714.

[00114] In response to the failure report indicating that the CPAC execution condition was not met, the T-MN 120C may determine adaptation information for the CPAC execution condition at 716. In some example embodiments, the T-MN 120C may collect a certain number of the failure reports relating to the CHO and CPAC configuration and analyze statistics of the SCG failures to determine whether the SCG failures were caused by the unmet CPAC execution condition or by other factors. If the SCG failures were caused by the unmet CPAC execution condition, the T-MN 120C may determine adaptation information e.g. one or more new values or delta amounts for one or more parameters of the CPAC execution condition to make the CPAC execution condition be fulfilled earlier, e.g. before expiry of the T310 timer, thereby eliminating or reducing the SCG failures. The T-MN 120C may determine the adaptation information for the CPAC execution condition based on the failure reports, e.g. the N last measurements of the target PSCell and optionally the N last measurements of the source PSCell indicated in the failure report.

[00115] At 718, the T-MN 120C may adapt the CPAC execution condition based on the determined adaptation information. For example, the T-MN 120C may determine a new CPAC execution condition taking into account the adaptation information when it receives a new handover request from the S-MN 120A.

[00116] In the processes 200-700, the UE reports failure information indicating which of the CHO and CPAC execution conditions was not met at the time of MCG or SCG failure, then the network can distinguish whether the failure was caused by any of the two conditions that are bonded to one single CHO and CPAC configuration. Hence, the network can adapt the relevant condition of the CHO and CPAC configuration. The condition adaptation may be implemented in a centralized manner at the 0AM or in a distributed manner at respective RAN nodes which determined the problematic execution condition.

[00117] Fig 8 illustrates an example method 800 for adaptation of execution conditions associated to a combined conditional handover and cell addition or change configuration, e.g. the CHO and CPAC configuration discussed above. The method 800 may be implemented at a terminal device e.g. the UE 110 described above. It is assumed that the terminal device operates in a dual connectivity (DC) mode, connecting to a first network node acting as a maser node e.g. the S-MN 120A discussed above and a third network node acting as a secondary node e.g. the S-SN 120B discussed above.

[00118] Referring to Fig. 8, the method 800 may comprise a step 810 of receiving by the terminal device from the first network node a configuration message comprising at least one execution condition for a conditional handover and at least one execution condition for a cell addition or change. The configuration may indicate a candidate PCell and optionally one or more MCG SCells prepared at a second network node, e.g. the T-MN 120C discussed above, for the conditional handover operation, and a candidate PSCell and optionally one or more SCG SCells prepared at a fourth network node, e.g. the T-SN 120D discussed above, for the cell additional or change operation. The at least one execution condition for the conditional handover and the at least one execution condition for the cell addition or change may be tied to each other, which means the conditional handover and the cell addition or change would not be triggered unless the at least one execution condition for the conditional handover and the at least one execution condition for the cell addition or change both are met.

[00119] After receiving the configuration message, the terminal device may evaluate whether the at least one execution condition for the conditional handover and the at least one execution condition for the cell addition or change are met at a step 820. For example, as the terminal device moves from the first network node and the third network node towards the second network node and the fourth network node, one of the at least one condition for the conditional handover and the at least one condition for the cell addition or change may be met first, while the other may be not met yet.

[00120] The method 800 may further comprise a step 830 of detecting a radio link failure of a radio connection between the terminal device and the first network node before both of the at least one condition for the conditional handover and the at least one condition for the cell addition or change are met. In other words, at least one of the at least one condition for the conditional handover and the at least one condition for the cell addition or change is not met at the time of the radio link failure. For example, as the terminal device moves from the first network node (i.e., the S-MN) towards the second network node (i.e., the candidate T-MN), the terminal device may experience an interruption with the S-MN link due to low link quality of the first network node (e.g. low RSRP) and / or interferences of the second network node. The terminal device may start a T310 timer for the S-MN interruption. If the conditional handover and cell addition or change is not triggered (i.e., at least one of the at least one condition for the cell addition or change and the at least one condition for the conditional handover is not met yet) and the T310 timer expires (i.e., the S-MN link does not recover), the terminal device may declare the radio link failure with the first network node.

[00121] In response to the radio link failure with the first network node (i.e., the S-MN), the terminal device may establish a radio connection with the second network node (i.e., the candidate T-MN) at a step 840. For example, the terminal device may initiate an RRC connection re-establishment procedure to connect to a suitable cell supported by the second network node.

[00122] After establishing the radio connection with the second network node, the terminal device may perform a step 850 of transmitting a failure report indicating the radio link failure taking place before both the at least one condition for the conditional handover and the at least one condition for the cell addition or change were met to the second network node. In some example embodiments, the failure report may contain an identifier of the conditional handover and cell addition or change configuration and a cause of not triggering the conditional handover and cell addition or change based on the configuration. For instance, the cause may indicate which of the at least one condition for the conditional handover and the at least one condition for the cell addition or change was not met, which of the at least one condition for the conditional handover and the at least one condition for the cell addition or change was met, or both. Hence the network can know which condition potentially delayed the conditional handover and cell addition or change execution and consequently caused the radio link failure.

[00123] In some example embodiments, the failure report may further comprise additional information for adapting the problematic condition which potentially caused the radio link failure. For example, the failure report may further comprise at least one of the following: • the at least one condition for the conditional handover or the at least one condition for the cell addition or change which was not met, e.g. threshold and offset parameters of the condition, • information of a target cell relating to the unmet condition, e.g. physical cell identifier (PCI) and frequency of the target cell, • N last measurements on the target cell before the radio link failure, where N is a positive integer, • information of a source cell relating to the unmet condition, e.g. PCI and frequency of the source cell, • N last measurements on the source cell before the radio link failure, or • an indication indicating that a time to trigger (TTT) timer of the unmet condition was running at the time of the radio link failure.

[00124] In some example embodiments, the method 800 may further comprise a step of receiving by the terminal device from the first network node a failure report configuration before the radio link failure (not shown in Fig. 8). The failure report configuration may specify at least one of the following: • contents of the failure report; or • criteria for triggering the failure report. Then the terminal device may trigger the failure report and log relevant information for the failure report based on the failure report configuration. In some example embodiments, the criteria for triggering the failure report may comprise that at least one of the at least one condition for the conditional handover and the at least one condition for the cell addition or change is not met at the time of the radio link failure.

[00125] Fig 9 illustrates an example method 900 for adaptation of execution conditions associated to a combined conditional handover and cell addition or change configuration, e.g. the CHO and CPAC configuration discussed above. The method 900 may be implemented at a second network node, e.g. the T-MN 120C or any other base station which the UE 110 connects to after the radio link failure with the S-MN 120A as described above.

[00126] Referring to Fig. 9, the method 900 may comprise a step 910 of establishing, by the second network node, a radio connection with a terminal device, e.g. the UE 110 discussed above, and a step 920 of receiving a failure report from the terminal device. The failure report may indicate that a radio link failure took place between the terminal device and a first network node when at least one of at least one condition for a conditional handover and at least one condition for a cell addition or change was not met at the terminal device. In some example embodiments, the first network node acted as a master node for the terminal device before the radio link failure, e.g. the S-MN 120A discussed above.

[00127] In some example embodiments, the failure report may contain an identifier of a configuration comprising the at least one condition for the conditional handover and the at least one condition for the cell addition or change. For example, the configuration may be a combined conditional handover and conditional PSCell addition or change configuration. The failure report may further comprise a cause of not triggering the conditional handover and cell addition or change based on the configuration. The cause may indicate which of the at least one condition for the conditional handover and the at least one condition for the cell addition or change was / were not met, which of the at least one condition for the conditional handover and the at least one condition for the cell addition or change was met, or both. It would be appreciated that the conditional handover and the cell addition or change can be triggered only when both conditions are met. Hence the network can know from the failure report which condition(s) potentially delayed execution of the conditional handover and cell addition or change and consequently caused the radio link failure.

[00128] In some example embodiments, the failure report may further comprise additional information for adapting the problematic condition(s) which potentially caused the radio link failure. For example, the failure report may further comprise at least one of the following: • the at least one condition for the conditional handover or the at least one condition for the cell addition or change which was not met, e.g. threshold and offset parameters of the condition, • information of a target cell relating to the unmet condition, e g. physical cell identifier (PCI) and frequency of the target cell, • N last measurements on the target cell before the radio link failure, where N is a positive integer, • information of a source cell relating to the unmet condition, e.g. PCI and frequency of the source cell, • N last measurements on the source cell before the radio link failure, or • an indication indicating that a time to trigger (TTT) timer of the unmet condition was running at the time of the radio link failure.

[00129] After receiving the failure report, the second network node may transmit at a step 930 the failure report to an operations administration and maintenance (0AM) entity, e.g. the 0AM 140 discussed above, or to the first network node, e.g. the S-MN 120A discussed above. Alternatively or additionally, if the unmet execution condition indicated in the failure report was determined by the second network node, i.e., the at least one execution condition for the cell addition or change determined at the second network node was not met, the second network node may determine at 940 adaptation information for the unmet condition, i.e. the at least one condition for the cell addition or change.

[00130] In some example embodiments, if the failure report is transmitted to the 0AM entity, the method may further comprise a step of receiving from the 0AM entity adaptation information for the unmet condition. If the adaptation information is for the at least one condition for the conditional handover, the second network node may transmit the adaptation information to the first network node where the adaptation information may be applied. If the adaptation information is for the at least one condition for the cell addition or change determined at the second network node, the second network node may adapt the at least one condition for the cell addition or change based on the adaptation information.

[00131] In some example embodiments, if the failure report is transmitted to the first network node, the method may further comprise a step of receiving from the first network node adaptation information for the at least one condition for the cell addition or change determined at the second network node. Then the second network node may adapt the at least one condition for the cell addition or change based on the adaptation information.

[00132] In some example embodiments, the second network node may determine and transmit a failure report configuration to the first network node before establishing the radio connection with the terminal device. The failure report configuration may specify contents of the failure report, and / or criteria for triggering the failure report. The first network node may transmit the failure report configuration to the terminal device before a radio link failure occurs therebetween.

[00133] Fig. 10 illustrates an example method 1000 for adaptation of execution conditions associated to a combined conditional handover and cell addition or change configuration, e.g. the CHO and CPAC configuration discussed above. The method 1000 may be implemented at a first network node e.g. the S-MN 120A described above.

[00134] Referring to Fig. 10, the method 1000 may comprise a step 1010 of transmitting, by the first network node to a terminal device (e.g. the UE 110 discussed above), a configuration message comprising at least one condition for a conditional handover and at least one condition for a cell addition or change, and a step 1020 of receiving a failure report from a second network device, e.g. the T-MN 120C or any other base station which the UE 110 connects to after the radio link failure with the S-MN 120A as discussed above. It would be appreciated that the conditional handover and the cell addition or change can be triggered only when both conditions are met. The failure report may indicate that a radio link failure took place between the terminal device and the first network node when at least one of the at least one condition for the conditional handover and the at least one condition for the cell addition or change was not met at the terminal device.

[00135] In some example embodiments, the failure report may contain an identifier of a configuration comprising the at least one condition for the conditional handover and the at least one condition for the cell addition or change. For example, the configuration may be a combined conditional handover and conditional PSCell addition or change configuration. The failure report may further comprise a cause of not triggering the conditional handover and cell addition or change based on the configuration. The cause may indicate which of the at least one condition for the conditional handover and the at least one condition for the cell addition or change was / were not met, which of the at least one condition for the conditional handover and the at least one condition for the cell addition or change was met, or both. Hence the network can know from the failure report which condition(s) potentially delayed execution of the conditional handover and cell addition or change and consequently caused the radio link failure.

[00136] In some example embodiments, the failure report may further comprise additional information for adapting the problematic condition(s) which potentially caused the radio link failure. For example, the failure report may further comprise at least one of the following: • the at least one condition for the conditional handover or the at least one condition for the cell addition or change which was not met, e.g. threshold and offset parameters of the condition, • information of a target cell relating to the unmet condition, e.g. physical cell identifier (PCI) and frequency of the target cell, • N last measurements on the target cell before the radio link failure, where N is a positive integer, • information of a source cell relating to the unmet condition, e.g. physical cell identifier (PCI) and frequency of the source cell, • N last measurements on the source cell before the radio link failure, or • an indication indicating that a time to trigger (TTT) timer of the unmet condition was running at the time of the radio link failure.

[00137] After receiving the failure report, the first network node may transmit at a step 1030 the failure report to an operations administration and maintenance (0AM) entity, e.g. the 0AM 140 discussed above. Alternatively or additionally, if the unmet execution condition indicated in the failure report was determined by the first network node, i.e., the at least one execution condition for the conditional handover was not met, the first network node may determine at a step 1040 adaptation information for the unmet condition, i.e. the at least one condition for the conditional handover.

[00138] In some example embodiments, if the failure report is transmitted to the 0AM entity, the method may further comprise a step of receiving from the 0AM entity adaptation information for the unmet condition. If the adaptation information is for the at least one condition for the conditional handover, the first network node may adapt the at least one condition for the conditional handover based on the adaptation information. If the adaptation information is for the at least one condition for the cell addition or change, the first network node may transmit the adaptation information to the second network node if the at least one condition for the cell addition or change was determined by the second network node.

[00139] In some example embodiments, the first network node may transmit a failure report configuration to the terminal device before the radio link failure occurred between the first network node and the terminal device. The failure report configuration may be determined by the first network node or received from the second network node if the second network node acted as a candidate target master node for the terminal device before the radio link failure, and it may specify contents of the failure report, and / or criteria for triggering the failure report.

[00140] Fig 11 illustrates an example method 1100 for adaptation of execution conditions associated to a combined conditional handover and cell addition or change configuration, e.g. the CHO and CPAC configuration discussed above. The method 1100 may be implemented at an operations administration and maintenance (0AM) entity, e.g. the 0AM 140 described above.

[00141] Referring to Fig. 11, the method 1100 may comprise a step 1110 of receiving, by the 0AM entity from a first network node or a second network node, a failure report indicating a radio link failure taking place between a terminal device and the first network node when at least one of at least one condition for a conditional handover and at least one condition for a cell addition or change was not met. In some example embodiments, the first network node acted as a master node for the terminal device before the radio link failure, and the terminal device connected to the second network node after the radio link failure. In some example embodiments, the second network node was configured as a candidate target master node for the terminal device before the radio link failure. It is assumed that the terminal device transmitted the failure report to the second network node first, and then the second network node may transmit the failure report to the 0AM entity directly or via the first network node.

[00142] In some example embodiments, the failure report may contain an identifier of a configuration comprising the at least one condition for the conditional handover and the at least one condition for the cell addition or change. For example, the configuration may be a combined conditional handover and conditional PSCell addition or change configuration. It would be appreciated that the combined conditional handover and cell addition or change can be triggered only when both execution conditions are met. The failure report may further comprise a cause of not triggering the conditional handover and cell addition or change based on the configuration. The cause may indicate which of the at least one condition for the conditional handover and the at least one condition for the cell addition or change was / were not met, which of the at least one condition for the conditional handover and the at least one condition for the cell addition or change was met, or both. Hence the 0AM entity can know from the failure report which condition(s) potentially delayed execution of the conditional handover and cell addition or change and consequently caused the radio link failure.

[00143] In some example embodiments, the failure report may further comprise additional information for adapting the problematic condition(s) which potentially caused the radio link failure. For example, the failure report may further comprise at least one of the following: • the at least one condition for the conditional handover or the at least one condition for the cell addition or change which was not met, e.g. threshold and offset parameters of the condition, • information of a target cell relating to the unmet condition, e.g. physical cell identifier (PCI) and frequency of the target cell, • N last measurements on the target cell before the radio link failure, where N is a positive integer, • information of a source cell relating to the unmet condition, e.g. physical cell identifier (PCI) and frequency of the source cell, • N last measurements on the source cell before the radio link failure, or • an indication indicating that a time to trigger (TTT) timer of the unmet condition was running at the time of the radio link failure.

[00144] After receiving the failure report, the 0AM entity may determine adaptation information for the unmet condition indicated in the failure report at a step 1120, and transmit the determined adaptation information to a relevant network node at a step 1130. In some example embodiments, the 0AM entity may transmit the adaptation information to the first network node in case the adaptation information is determined for the at least one condition for the conditional handover, or to the second network node in case the adaptation information is determined for the at least one condition for the cell addition or change. In some other example embodiments, the 0AM entity may transmit the adaptation information to the network node from which the failure report was received, regardless of for which condition the adaptation information is determined.

[00145] Fig 12 illustrates an example method 1200 for adaptation of execution conditions associated to a combined conditional handover and cell addition or change configuration, e.g. the CHO and CPAC configuration discussed above. The method 1200 may be implemented at a terminal device e.g. the UE 110 described above. It is assumed that the terminal device operates in a dual connectivity (DC) mode, connecting to a first network node acting as a maser node e.g. the S-MN 120A discussed above and a third network node acting as a secondary node e.g. the S-SN 120B discussed above.

[00146] Referring to Fig. 12, the method 1200 may comprise a step 1210 of receiving by the terminal device from the first network node a configuration message comprising at least one execution condition for a conditional handover and at least one execution condition for a cell addition or change. The configuration may indicate a candidate PCell and optionally one or more MCG SCells prepared at a second network node, e.g. the T-MN 120C discussed above, for the conditional handover operation, and a candidate PSCell and optionally one or more SCG SCells prepared at a fourth network node, e.g. the T-SN 120D discussed above, for the cell additional or change operation. The at least one execution condition for the conditional handover and the at least one execution condition for the cell addition or change may be tied to each other, which means the conditional handover and the cell addition or change would not be triggered unless the at least one execution condition for the conditional handover and the at least one execution condition for the cell addition or change both are met.

[00147] After receiving the configuration message, the terminal device may evaluate whether the at least one execution condition for the conditional handover and the at least one execution condition for the cell addition or change are met at a step 1220. For example, as the terminal device moves from the first network node and the third network node towards the second network node and the fourth network node, one of the at least one condition for the conditional handover and the at least one condition for the cell addition or change may be met first, while the other may be not met yet.

[00148] The method 1200 may further comprise a step 1230 of detecting a connection failure between the terminal device and the third network node before both of the at least one condition for the conditional handover and the at least one condition for the cell addition or change are met, i.e. before the combined conditional handover and cell addition or change is triggered. For example, as the terminal device moves from the third network node (i.e., the S-SN) towards the fourth network node (i.e., the candidate T-SN), the terminal device may experience an interruption with the S-SN link due to low link quality of the third network node (e.g. low RSRP) and / or interferences of the fourth network node. The terminal device may start a T310 timer for the S-SN interruption. If the conditional handover and cell addition or change is not triggered (i.e., either the at least one condition for the cell addition or change or the at least one condition for the conditional handover is not met yet) and the T310 timer expires (i.e., the S-SN link does not recover), the terminal device may declare the connection failure with the third network node, i.e. SCG failure.

[00149] The method 1200 may further comprise a step 1240 of transmitting a failure report indicating the SCG failure taking place before both the at least one condition for the conditional handover and the at least one condition for the cell addition or change were met to the first network node. In some example embodiments, the failure report may contain an identifier of the conditional handover and cell addition or change configuration and a cause of not triggering the conditional handover and cell addition or change based on the configuration. For instance, the cause may indicate which of the at least one condition for the conditional handover and the at least one condition for the cell addition or change was / were not met, which of the at least one condition for the conditional handover and the at least one condition for the cell addition or change was met, or both. Hence the network can know which condition(s) potentially delayed the conditional handover and cell addition or change execution and consequently caused the SCG failure.

[00150] In some example embodiments, the failure report may further comprise additional information for adapting the problematic condition(s) which potentially caused the SCG failure. For example, the failure report may further comprise at least one of the following: • the at least one condition for the conditional handover or the at least one condition for the cell addition or change which was not met, e.g. threshold and offset parameters of the condition, • information of a target cell relating to the unmet condition, e.g. physical cell identifier (PCI) and frequency of the target cell, • N last measurements on the target cell before the SCG failure, where N is a positive integer, • information of a source cell relating to the unmet condition, e.g. PCI and frequency of the source cell, • N last measurements on the source cell before the SCG failure, or • an indication indicating that a time to trigger (TTT) timer of the unmet condition was running at the time of the radio link failure.

[00151] In some example embodiments, the method 1200 may further comprise a step of receiving by the terminal device from the first network node a failure report configuration before the SCG failure (not shown). The failure report configuration may specify at least one of the following: • contents of the failure report; or • criteria for triggering the failure report. Then the terminal device may trigger the failure report and log relevant information for the failure report based on the failure report configuration. In some example embodiments, the criteria for triggering the failure report may comprise that at least one of the at least one condition for the conditional handover and the at least one condition for the cell addition or change is not met at the time of the SCG failure.

[00152] Fig 13 illustrates an example method 1300 for adaptation of execution conditions associated to a combined conditional handover and cell addition or change configuration, e.g. the CHO and CPAC configuration discussed above. The method 1300 may be implemented at a second network node e.g. the T-MN 120C described above.

[00153] Referring to Fig. 13, the method 1300 may comprise a step 1310 of transmitting at least one condition for a cell addition or change from the second network node to a first network node. For instance, the second network node may determine and transmit the at least one condition for the cell addition or change in response to a handover request received from the first network node. The first network node may act as a master node e.g. the S-MN 120A discussed above for a terminal device e.g. the UE 110 discussed above, and intend to handover the terminal device to the second network node. The second network node may determine a combined conditional handover and cell addition or change configuration comprising the at least one condition for the cell addition or change for the terminal device, and transmit the configuration to the first network node at the step 1310.

[00154] The second network node may receive a failure report from the first network node at a step 1320. The failure report may indicate that an SCG failure took place between the terminal device and a third network node when at least one of at least one condition for a conditional handover and the at least one condition for the cell addition or change was not met at the terminal device. The third network node acted as a secondary node supporting the SCG cells for the terminal device, e.g. the S-SN 120B discussed above.

[00155] In some example embodiments, the failure report may contain an identifier of the configuration comprising the at least one condition for the conditional handover and the at least one condition for the cell addition or change. For example, the configuration may be a combined conditional handover and conditional PSCell addition or change configuration. The failure report may further comprise a cause of not triggering the conditional handover and cell addition or change based on the configuration. The cause may indicate that the at least one condition for the cell addition or change was not met at the time of SCG failure. Hence the second network node can know from the failure report that the at least one condition for the cell addition or change potentially delayed execution of the conditional handover and cell addition or change and consequently caused the SCG failure.

[00156] In some example embodiments, the failure report may further comprise additional information for adapting the at least one condition for the cell addition or change which potentially caused the SCG failure. For example, the failure report may further comprise at least one of the following: • the at least one condition for the cell addition or change, e.g. threshold and offset parameters of the condition, • information of a target cell relating to the at least one condition for the cell addition or change, e.g. physical cell identifier (PCI) and frequency of the target cell, • N last measurements on the target cell before the SCG failure, where N is a positive integer, • information of a source cell relating to the at least one condition for the cell addition or change, e.g. PCI and frequency of the source cell, • N last measurements on the source cell before the SCG failure, or • an indication indicating that a time to trigger (TTT) timer of the unmet condition was running at the time of the radio link failure.

[00157] After receiving the failure report, the second network node may transmit the failure report to an operations administration and maintenance (0AM) entity, e.g. the 0AM 140 discussed above, at a step 1330, or determine adaptation information for the atleast one condition for the cell addition or change at a step 1340.

[00158] In some example embodiments, if the failure report is transmitted to the 0AM entity at the step 1330, the method may further comprise a step of receiving from the 0AM entity adaptation information for the at least one condition for the cell addition or change (not shown in Fig. 13). The second network node may adapt the at least one condition for the cell addition or change based on the adaptation information received from the 0AM entity, or based on the adaptation information determined by the second network node at the step 1340.

[00159] In some example embodiments, the second network node may determine and transmit a failure report configuration to the first network node before receiving the failure report from the first network node. The failure report configuration may specify contents of the failure report, and / or criteria for triggering the failure report. The first network node may transmit the failure report configuration to the terminal device before the SCG failure occurs.

[00160] Fig 14 illustrates an example method 1400 for adaptation of execution conditions associated to a combined conditional handover and cell addition or change configuration, e.g. the CHO and CPAC configuration discussed above. The method 1400 may be implemented at a first network node e.g. the S-MN 120A described above.

[00161] Referring to Fig. 14, the method 1400 may comprise a step 1410 of transmitting, by the first network node to a terminal device (e.g. the UE 110 discussed above), a configuration message comprising at least one condition for a conditional handover and at least one condition for a cell addition or change, and a step 1420 of receiving a failure report from the terminal device. In some example embodiments, the at least one condition for the conditional handover and the at least one condition for the cell addition or change may be tied to each other, i.e., only when both conditions are met, the conditional handover and the cell addition or change can be triggered. The failure report may indicate that an SCG failure took place between the terminal device and a third network node when at least one of the at least one condition for the conditional handover and the at least one condition for the cell addition or change was not met at the terminal device. The first network node may act as a master node supporting MCG cells for the terminal device, and the third network node may act as a secondary node supporting SCG cells for the terminal device.

[00162] In some example embodiments, the failure report may contain an identifier of the configuration comprising the at least one condition for the conditional handover and the at least one condition for the cell addition or change. The failure report may further comprise a cause of not triggering the conditional handover and cell addition or change based on the configuration. The cause may indicate which of the at least one condition for the conditional handover and the at least one condition for the cell addition or change was / were not met, which of the at least one condition for the conditional handover and the at least one condition for the cell addition or change was met, or both. Hence the network can know from the failure report which condition(s) potentially delayed execution of the conditional handover and cell addition or change and consequently caused the SCG failure.

[00163] In some example embodiments, the failure report may further comprise additional information for adapting the problematic condition(s) which potentially caused the SCG failure. For example, the failure report may further comprise at least one of the following: • the at least one condition for the conditional handover or the at least one condition for the cell addition or change which was not met, e.g. threshold and offset parameters of the condition, • information of a target cell relating to the unmet condition, e.g. physical cell identifier (PCI) and frequency of the target cell, • N last measurements on the target cell before the SCG failure, where N is a positive integer, • information of a source cell relating to the unmet condition, e.g. PCI and frequency of the source cell, • N last measurements on the source cell before the SCG failure, or • an indication indicating that a time to trigger (TTT) timer of the unmet condition was running at the time of the SCG failure.

[00164] After receiving the failure report, the first network node may transmit the failure report to an operations administration and maintenance (0AM) entity, e.g. the 0AM 140 discussed above, at a step 1430. If the failure report indicates that the at least one condition for the cell addition or change was not met, the first network node may transmit the failure report to a second network node instead which determined the at least one condition for the cell addition or change.

[00165] In some example embodiments, if the failure report indicates that the at least one condition for the conditional handover was not met, the first network node may determine adaptation information for the at least one condition for the conditional handover at a step 1440. Then the first network node may adapt the at least one condition for the conditional handover based on the adaptation information.

[00166] In some example embodiments, if the failure report is transmitted to the 0AM entity at the step 1430, the method may further comprise a step of receiving from the 0AM entity adaptation information for the unmet condition (not shown in Fig. 14). If the adaptation information is for the at least one condition for the conditional handover, the first network node may adapt the at least one condition for the conditional handover based on the adaptation information. If the adaptation information is for the at least one condition for the cell addition or change, the first network node may transmit the adaptation information to the second network node where the adaptation information may be applied.

[00167] In some example embodiments, the first network node may transmit a failure report configuration to the terminal device before the SCG failure occurred between the third network node and the terminal device. The failure report configuration may be determined by the first network node or received from the second network node, and it may specify contents of the failure report, and / or criteria for triggering the failure report.

[00168] Fig 15 illustrates an example method 1500 for adaptation of execution conditions associated to a combined conditional handover and cell addition or change configuration, e.g. the CHO and CPAC configuration discussed above. The method 1500 may be implemented at an operations administration and maintenance (0AM) entity, e.g. the 0AM 140 described above.

[00169] Referring to Fig. 15, the method 1500 may comprise a step 1510 of receiving, by the OAM entity from a first network node or a second network node, a failure report indicating an SCG failure taking place between a terminal device and a third network node when at least one of at least one condition for a conditional handover and at least one condition for a cell addition or change was not met. In some example embodiments, the first network node may act as a master node (e.g. the S-MN 120A discussed above) for the terminal device, the third network node may act as a secondary node (e.g. the S-SN 120B discussed above) for the terminal device, and the second network node may be configured as a candidate target master node which determines the at least one condition for the cell addition or change for the terminal device. It is assumed that the terminal device experienced the SCG failure with the third network node and transmitted the failure report to the first network node. Then the first network node may transmit the failure report to the OAM entity directly or via the second network node.

[00170] In some example embodiments, the failure report may contain an identifier of the configuration comprising the at least one condition for the conditional handover and the at least one condition for the cell addition or change. For example, the configuration may be a combined conditional handover and conditional PSCell addition or change configuration. It would be appreciated that the combined conditional handover and cell addition or change can be triggered only when both execution conditions are met. The failure report may further comprise a cause of not triggering the conditional handover and cell addition or change based on the configuration. The cause may indicate which of the at least one condition for the conditional handover and the at least one condition for the cell addition or change was not met, which of the at least one condition for the conditional handover and the at least one condition for the cell addition or change was met, or both. Hence the OAM entity can know from the failure report which condition potentially delayed execution of the conditional handover and cell addition or change and consequently caused the SCG failure.

[00171] In some example embodiments, the failure report may further comprise additional information for adapting the problematic condition which potentially caused the SCG failure. For example, the failure report may further comprise at least one of the following: • the at least one condition for the conditional handover or the at least one condition for the cell addition or change which was not met, e.g. threshold and offset parameters of the condition, • information of a target cell relating to the unmet condition, e.g. physical cell identifier (PCI) and frequency of the target cell, • N last measurements on the target cell before the SCG failure, where N is a positive integer, • information of a source cell relating to the unmet condition, e.g. PCI and frequency of the source cell, • N last measurements on the source cell before the SCG failure, or • an indication indicating that a time to trigger (TTT) timer of the unmet condition was running at the time of the SCG failure.

[00172] After receiving the failure report, the 0AM entity may determine adaptation information for the unmet condition indicated in the failure report at a step 1520, and transmit the determined adaptation information to a relevant network node at a step 1530. In some example embodiments, the 0AM entity may transmit the adaptation information to the first network node in case the adaptation information is determined for the at least one condition for the conditional handover, or to the second network node in case the adaptation information is determined for the at least one condition for the cell addition or change. In some other example embodiments, the 0AM entity may transmit the adaptation information to the network node from which the failure report was received, regardless of for which condition the adaptation information is determined.

[00173] Fig 16 is a schematic block diagram illustrating an example apparatus 1600. The apparatus 1600 may be implemented to comprise or to form at least a part of a terminal device such as the UE 110 discussed above to perform at least a part of operations related to the UE 110. The blocks of the apparatus 1600 may be implemented with software, hardware, firmware or any combination thereof.

[00174] Referring to Fig. 16, the apparatus 1600 may comprise a means 1610 for receiving from a first network node a configuration message comprising at least one condition for a conditional handover and at least one condition for a cell addition or change, a means 1620 for evaluating whether the at least one condition for the conditional handover and the at least one condition for the cell addition or change are met, a means 1630 for detecting a radio link failure of a connection between the terminal device and the first network node before both of the at least one conditions are met, a means 1640 for establishing a radio connection with a second network node in response to the detected radio link failure, and a means 1650 for transmitting to the second network node a failure report indicating the radio link failure taking place before both of the at least one conditions were met.

[00175] In some example embodiments, the apparatus 1600 may further comprise a means (not shown) for receiving a failure report configuration from the first network node. The failure report configuration may specify contents of the failure report, and / or criteria for triggering the failure report.

[00176] Fig. 17 is a schematic block diagram illustrating an example apparatus 1700. The apparatus 1700 may be implemented to comprise or to form at least a part of a second network node, such as the T-MN 120C or any other base station the UE 110 connects to after a radio link failure as discussed above, to perform at least a part of operations related to the second network node. The blocks of the apparatus 1700 may be implemented with software, hardware, firmware or any combination thereof.

[00177] Referring to Fig. 17, the apparatus 1700 may comprise a means 1710 for establishing a radio connection with a terminal device, and a means 1720 for receiving a failure report from the terminal device. In some example embodiments, the failure report may indicate a radio link failure with a first network node taking place when at least one of at least one condition for a conditional handover and at least one condition for a cell addition or change was not met.

[00178] In some example embodiments, the apparatus 1700 may further comprise a third means 1730 for transmitting the failure report to an operations administration and maintenance (0AM) entity or to the first network node.

[00179] In some example embodiments, the apparatus 1700 may further comprise a fourth means 1740 for determining adaptation information for the at least one condition for the cell addition or change based on the failure report, in case the at least one condition for the cell addition or change was determined by the second network node and was not met at the time when the radio link failure took place.

[00180] In some example embodiments, the apparatus 1700 may further comprise a means (not shown) for receiving from the 0AM entity adaptation information for the at least one condition for the conditional handover or the at least one condition for the cell addition or change which was not met, and a means (not shown) for transmitting the adaptation information to the first network node in case the adaptation information is for the at least one condition for the conditional handover which was not met, or a means (not shown) for adapting the at least one condition for the cell addition or change based on the adaptation information in case the adaptation information is for the at least one condition for the cell addition or change which was not met,

[00181] In some example embodiments, the apparatus 1700 may further comprise a means (not shown) for receiving from the first network node adaptation information for the at least one condition for the cell addition or change which was not met, and a means (not shown) for adapting the at least one condition for the cell addition or change based on the adaptation information.

[00182] In some example embodiments, the apparatus 1700 may further comprise a means (not shown) for transmitting a failure report configuration to the first network node before establishing the radio connection with the terminal device. The failure report configuration may specify contents of the failure report, and / or criteria for triggering the failure report.

[00183] Fig 18 is a schematic block diagram illustrating an example apparatus 1800. The apparatus 1800 may be implemented to comprise or to form at least a part of a first network node such as the S-MN 120A discussed above to perform at least a part of operations related to the S-MN 120A. The blocks of the apparatus 1800 may be implemented with software, hardware, firmware or any combination thereof

[00184] Referring to Fig. 18, the apparatus 1800 may comprise a means 1810 for transmitting to a terminal device a configuration message comprising at least one condition for a conditional handover and at least one condition for a cell addition or change, and a means 1820 for receiving a failure report from a second network device. The failure report may indicate a radio link failure taking place between the terminal device and the first network node when at least one of the at least one condition for the conditional handover and the at least one condition for the cell addition or change was not met.

[00185] In some example embodiments, the apparatus 1800 may further comprise a means 1830 for transmitting the failure report to an operations administration and maintenance (0AM) entity, or a means 1840 for determining adaptation information for the at least one condition for the conditional handover in case the failure report indicates that the at least one condition for the conditional handover was not met.

[00186] Fig 19 is a schematic block diagram illustrating an example apparatus 1900. The apparatus 1900 may be implemented to comprise or to form at least a part of an operations administration and maintenance (0AM) entity such as the 0AM 140 discussed above to perform at least a part of operations related to the 0AM 140. The blocks of the apparatus 1900 may be implemented with software, hardware, firmware or any combination thereof.

[00187] Referring to Fig. 19, the apparatus 1900 may comprise a means 1910 for receiving a failure report from a first network node or a second network device. The failure report may indicate a radio link failure taking place between a terminal device and the first network node when at least one of at least one condition for a conditional handover and at least one condition for a cell addition or change was not met.

[00188] In some example embodiments, the apparatus 1900 may further comprise a means 1920 for determining adaptation information for the at least one condition for the conditional handover or the at least one condition for the cell addition or change which was not met.

[00189] In some example embodiments, the apparatus 1900 may further comprise a means 1930 for transmitting the adaptation information to a relevant network node. For instance, the means 1930 may transmit the adaptation information to the first network node in case the adaptation information is determined for the at least one condition for the conditional handover which was not met, to the second network node in case the adaptation information is determined for the at least one condition for the cell addition or change which was not met, or to the network node from which the failure report is received regardless of for which condition the adaptation information is determined.

[00190] Fig 20 is a schematic block diagram illustrating an example apparatus 2000. The apparatus 2000 may be implemented to comprise or to form at least a part of a terminal device such as the UE 110 discussed above to perform at least a part of operations related to the UE 110. The blocks of the apparatus 2000 may be implemented with software, hardware, firmware or any combination thereof.

[00191] Referring to Fig. 20, the apparatus 2000 may comprise a means 2010 for receiving a configuration message comprising at least one condition for a conditional handover and at least one condition for a cell addition or change from a first network node, a means 2020 for evaluating whether the at least one condition for the conditional handover and the at least one condition for the cell addition or change are met, a means 2030 for detecting a failure of a connection with a third network node before both of the at least one conditions are met, and a means 2040 for transmitting to the first network node a failure report indicating the connection failure taking place before both of the at least one conditions were met.

[00192] In some example embodiments, the apparatus 2000 may further comprise a means (not shown) for receiving a failure report configuration from the first network node. The failure report configuration may specify contents of the failure report, and / or criteria for triggering the failure report.

[00193] Fig 21 is a schematic block diagram illustrating an example apparatus 2100. The apparatus 2100 may be implemented to comprise or to form at least a part of a second network node such as the T-MN 120C discussed above to perform at least a part of operations related to the T-MN 120C. The blocks of the apparatus 2100 may be implemented with software, hardware, firmware or any combination thereof.

[00194] Referring to Fig. 21, the apparatus 2100 may comprise a means 2110 for transmitting at least one condition for a cell addition or change to a first network node, and a means 2120 for receiving a failure report from the first network node. The failure report may indicate a connection failure taking place between a terminal device and a third network node when at least the at least one condition for the cell addition or change was not met.

[00195] In some example embodiments, the apparatus 2100 may further comprise a means 2130 for transmitting the failure report to an operations administration and maintenance (0AM) entity, or a means 2140 for determining adaptation information for the at least one condition for the cell addition or change.

[00196] In some example embodiments, the apparatus 2100 may further comprise a means (not shown) for receiving from the 0AM entity adaptation information for the at least one condition for the cell addition or change, and a means (not shown) for adapting the at least one condition for the cell addition or change based on the adaptation information.

[00197] In some example embodiments, the apparatus 2100 may further comprise a means (not shown) for transmitting a failure report configuration to the first network node before the means 2120 receives the failure report. For example, the failure report configuration may specify contents of the failure report, and / or criteria for triggering the failure report.

[00198] Fig 22 is a schematic block diagram illustrating an example apparatus 2200. The apparatus 2200 may be implemented to comprise or to form at least a part of a first network node such as the S-MN 120A discussed above to perform at least a part of operations related to the S-MN 120A. The blocks of the apparatus 2200 may be implemented with software, hardware, firmware or any combination thereof.

[00199] Referring to Fig. 22, the apparatus 2200 may comprise a means 2210 for transmitting to a terminal device a configuration message comprising at least one condition for a conditional handover and at least one condition for a cell addition or change, and a means 2220 for receiving a failure report from the terminal device. The failure report may indicate a connection failure taking place between the terminal device and a third network node when at least one of the at least one condition for the conditional handover and the at least one condition for the cell addition or change was not met.

[00200] In some example embodiments, the apparatus 2200 may further comprise a means 2230 for transmitting the failure report to an operations administration and maintenance (0AM) entity or, in case the at least one condition for the cell addition or change was not met, to a second network node which determined the at least one condition for the cell addition or change.

[00201] In some example embodiments, the apparatus 2200 may further comprise a means 2240 for determining adaptation information for the at least one condition for the conditional handover in case the at least one condition for the conditional handover was not met.

[00202] In some example embodiments, the apparatus 2200 may further comprise a means for receiving from the 0AM entity adaptation information for the at least one condition for the conditional handover or the at least one condition for the cell addition or change which was not met, and a means (not shown) for transmitting the adaptation information to the second network node in case the adaptation information is for the at least one condition for the cell addition or change, and a means (not shown) for adapting the at least one condition for the conditional handover based on the adaptation information in case the adaptation information is for the at least one condition for the conditional handover.

[00203] In some example embodiments, the apparatus 2200 may further comprise a means for transmitting a failure report configuration to the terminal device. In an example embodiment, the failure report may specify contents of the failure report, and / or criteria for triggering the failure report. The failure report configuration may be determined by the first network node or received from the second network node.

[00204] Fig 23 is a schematic block diagram illustrating an example apparatus 2300. The apparatus 2300 may be implemented to comprise or to form at least a part of an operations administration and maintenance (0AM) entity such as the 0AM 140 discussed above to perform at least a part of operations related to the 0AM 140. The blocks of the apparatus 2300 may be implemented with software, hardware, firmware or any combination thereof.

[00205] Referring to Fig. 23, the apparatus 2300 may comprise a means 2310 for receiving a failure report from a first network node or a second network device. The failure report may indicate a connection failure taking place between a terminal device and a third network node when at least one of at least one condition for a conditional handover and at least one condition for a cell addition or change was not met.

[00206] The apparatus 2300 may further comprise a means 2320 for determining adaptation information for the at least one condition for the conditional handover or the at least one condition for the cell addition or change which was not met, and a means 2330 for transmitting the adaptation information to a relevant network node. For example, the means 2330 may transmit the adaptation information to the first network node in case the adaptation information is determined for the at least one condition for the conditional handover which was not met, to the second network node in case the adaptation information is determined for the at least one condition for the cell addition or change which was not met, or to the first network node regardless of which of the at least one condition for the conditional handover and the at least one condition for the cell addition or change was not met since the failure report is received from the first network node.

[00207] Fig 24A illustrates an example terminal device 2410, Fig. 24B illustrates an example radio access network (RAN) device 2420, and Fig. 24C illustrates an example operations administration and maintenance (0AM) device 2430.

[00208] Referring to Fig. 24A, the terminal device 2410 may comprise one or more processors 2411, one or more memories 2412 and one or more transceivers 2413 interconnected through one or more buses 2414. The one or more buses 2414 may be address, data, or control buses, and may include any interconnection mechanism such as series of lines on a motherboard or integrated circuit, fiber, optics or other optical communication equipment, and the like. Each of the one or more transceivers 2413 may comprise a receiver and a transmitter, which are connected to one or more antennas 2416. The terminal device 2410 may wirelessly communicate with the RAN device 2420 through the one or more antennas 2416. The one or more memories 2412 may include instructions 2415 which, when executed by the one or more processors 2411, may cause the terminal device 2410 to perform operations relating to the UE 110 as described above.

[00209] Referring to Fig. 24B, the RAN device 2420 may comprise one or more processors 2421, one or more memories 2422, one or more transceivers 2423 and one or more network interfaces 2427 interconnected through one or more buses 2424. The one or more buses 2424 may be address, data, or control buses, and may include any interconnection mechanism such as a series of lines on a motherboard or integrated circuit, fiber, optics or other optical communication equipment, and the like. Each of the one or more transceivers 2423 may comprise a receiver and a transmitter, which are connected to one or more antennas 2426. The RAN device 2420 may operate as a master node, a secondary node, a candidate master node or a candidate secondary node for the terminal device 2410 in a dual connectivity mode, or as a single serving base station for the terminal device 2410 in a single connectivity mode. The RAN device 2420 may wirelessly communicate with terminal device 2410 through the one or more antennas 2426. The one or more network interfaces 2427 may provide wired or wireless communication links through which the RAN device 2420 may communicate with other network devices, entities, elements or functions. For example, the RAN device 2420 may communicate with the 0AM device 2430 via the wired or wireless connection and with a core network (not shown) via backhaul connections. The one or more memories 2422 may include instructions 2425 which, when executed by the one or more processors 2421, may cause the RAN device 2420 to perform operations relating to any one of the base stations 120 as described above.

[00210] Referring to Fig. 24C, the 0AM device 2430 may comprise one or more processors 2431, one or more memories 2432, and one or more network interfaces 2437 interconnected through one or more buses 2434. The one or more buses 2434 may be address, data, or control buses, and may include any interconnection mechanism such as a series of lines on a motherboard or integrated circuit, fiber, optics or other optical communication equipment, and the like. The one or more network interfaces 2437 may provide wired or wireless communication links through which the 0AM device 2430 may communicate with other network devices, entities, elements or functions. In some example embodiments, the 0AM device 2430 may connect to the RAN device 2420 directly or via a core network (not shown). The one or more memories 2432 may include instructions 2435 which, when executed by the one or more processors 2431, may cause the 0AM device 2430 to perform operations and procedures relating to the 0AM entity 140 as described above.

[00211] The one or more processors 2411, 2421 and 2431 discussed above may be of any appropriate type that is suitable for the local technical network, and may include one or more of general purpose processors, special purpose processor, microprocessors, a digital signal processor (DSP), one or more processors in a processor based multi-core processor architecture, as well as dedicated processors such as those developed based on Field Programmable Gate Array (FPGA) and Application Specific Integrated Circuit (ASIC). The one or more processors 2411, 2421 and 2431 may be configured to control other elements of the terminal / RAN / core network devices and operate in cooperation with them to implement the procedures discussed above.

[00212] The one or more memories 2412, 2422 and 2432 may include at least one storage medium in various forms, such as a transitory memory and / or a non-transitory memory. The transitory memory may include, but not limited to, for example, a random access memory (RAM) or a cache. The non-transitory memory may include, but not limited to, for example, a read only memory (ROM), a hard disk, a flash memory, and the like. The term “non-transitory,” as used herein, is a limitation of the medium itself (i.e., tangible, not a signal) as opposed to a limitation on data storage persistency (e.g., RAM vs. ROM). Further, the one or more memories 2412, 2422 and 2432 may include but not limited to an electric, a magnetic, an optical, an electromagnetic, an infrared, or a semiconductor system, apparatus, or device or any combination of the above.

[00213] It would be understood that blocks in the drawings may be implemented in various manners, including software, hardware, firmware, or any combination thereof. In some embodiments, one or more blocks may be implemented using software and / or firmware, for example, machine-executable instructions stored in the storage medium. In addition to or instead of machine-executable instructions, parts or all of the blocks in the drawings may be implemented, at least in part, by one or more hardware logic components For example, and without limitation, illustrative types of hardware logic components that can be used include Field-Programmable Gate Arrays (FPGAs), Application-Specific Integrated Circuits (ASICs), Application-Specific Standard Products (ASSPs), System-on-Chip systems (SOCs), Complex Programmable Logic Devices (CPLDs), etc.

[00214] Some example embodiments further provide program instruction or instructions which, when executed by one or more processors, may cause a device or apparatus to perform the procedures described above. The program instruction for carrying out procedures of the example embodiments may be written in any combination of one or more programming languages. The program instruction may be provided to one or more processors or controllers of a general purpose computer, special purpose computer, or other programmable data processing apparatus, such that the program instruction, when executed by the processor or controller, cause the functions / operations specified in the flowcharts and / or block diagrams to be implemented. The program instruction may execute entirely on a machine, partly on the machine, as a stand-alone software package, partly on the machine and partly on a remote machine or entirely on the remote machine or server.

[00215] Some example embodiments further provide a computer program product or a computer readable medium having the program instruction or instructions stored therein. The computer readable medium may be any tangible medium that may contain, or store a program for use by or in connection with an instruction execution system, apparatus, or device. The machine readable medium may be a machine readable signal medium or a machine readable storage medium. A machine readable medium may include but is not limited to an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing. More specific examples of the machine readable storage medium would include an electrical connection having one or more wires, a portable computer diskette, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or Flash memory), an optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.

[00216] As used herein, “at least one of the following: ” and “at least one of ” and similar wording, where the list of two or more elements are joined by “and” or “of’, mean at least any one of the elements, or at least any two or more of the elements, or at least all the elements.

[00217] Further, while operations are depicted in a particular order, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, to achieve desirable results. In certain circumstances, multitasking and parallel processing may be advantageous. Likewise, while several specific implementation details are contained in the above discussions, these should not be construed as limitations on the scope of the present disclosure, but rather as descriptions of features that may be specific to particular embodiments. Certain features that are described in the context of separate embodiments may also be implemented in combination in a single embodiment. Conversely, various features that are described in the context of a single embodiment may also be implemented in multiple embodiments separately or in any suitable sub-combination.

[00218] Throughout the present disclosure, reference to “one embodiment,” “an embodiment,” “some embodiments,” “other embodiments,” etc. indicates that one or more particular features, structures, steps, concepts, and / or characteristics in accordance with principles of the present disclosure may be included in connection with the embodiment. However, such references do not necessarily mean that all embodiments include the particular features, structures, steps, concepts, and / or characteristics, or that an embodiment includes all features, structures, steps, concepts, and / or characteristics. Some embodiments may include one or more such features, structures, steps, concepts, and / or characteristics, in various combinations thereof. It should be understood that one or more of the features, structures, steps, concepts, and / or characteristics described with reference to one embodiment can be combined with one or more of the features, structures, steps, concepts, and / or characteristics of any of the other embodiments provided herein. That is, any of the features, structures, steps, concepts, and / or characteristics described herein can be mixed and matched to create hybrid embodiments, and such hybrid embodiments are within the scope of the present disclosure. Moreover, references to “one embodiment,” “an embodiment,” “some embodiments,” “other embodiments,” etc. in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments necessarily mutually exclusive of other embodiments. It should further be understood that various features, structures, steps, concepts, and / or characteristics of disclosed embodiments are independent of and separate from one another, and may be used or present individually or in various combinations with one another to create alternative embodiments which are considered part of the present disclosure. Therefore, the present disclosure is not limited to only the embodiments specifically described herein, as it would be too cumbersome to describe all of the numerous possible combinations and subcombinations of features, structures, steps, concepts, and / or characteristics, and the examples of embodiments disclosed herein are not intended as limiting the broader aspects of the present disclosure.

[00219] Although the subject matter has been described in a language that is specific to structural features and / or method actions, it is to be understood the subject matter defined in the appended claims is not limited to the specific features or actions described above. On the contrary, the above-described specific features and actions are disclosed as an example of implementing the claims.

Claims

1. An apparatus, comprising:at least one processor; andat least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to:receive, by a terminal device from a first network node, a configuration message comprising at least one condition for a conditional handover and at least one condition for a cell addition or change;evaluate whether the at least one condition for the conditional handover and the at least one condition for the cell addition or change are met;detect a failure of a connection with a third network node before both of the at least one conditions are met; andtransmit to the first network node, a failure report indicating the connection failure taking place before both of the at least one conditions were met.

2. The apparatus of claim 1, wherein the apparatus is configured to:receive from the first network node, a failure report configuration specifying at least one of the following:contents of the failure report; or criteria for triggering the failure report.

3. The apparatus of claim 2, wherein the criteria for triggering the failure report comprises:at least one of the at least one condition for the conditional handover and the at least one condition for the cell addition or change is not met at the time when the connection failure with the third network node is detected.

4. The apparatus of any of claims 1 to 3, wherein the failure report comprises:an identifier of the configuration comprising the at least one condition for the conditional handover and the at least one condition for the cell addition or change, anda cause of not triggering the conditional handover and the cell addition or change based on the configuration.

5. The apparatus of claim 4, wherein the cause of not triggering the conditional handover and the cell addition or change indicates at least one of the following:which of the at least one condition for the conditional handover and the at least one condition for the cell addition or change was not met at the time when the connection failure with the third network node was detected, orwhich of the at least one condition for the conditional handover and the at least one condition for the cell addition or change was met at the time when the connection failure with the third network node was detected.

6. The apparatus of claim 4 or 5, wherein the failure report further comprises at least one of the following:the at least one condition for the conditional handover or the at least one condition for the cell addition or change which was not met at the time when the connection failure with the third network node was detected,information of a target cell relating to the at least one condition for the conditional handover or the at least one condition for the cell addition or change which was not met,N last measurements on the target cell, N being a positive integer, orinformation of a source cell relating to the at least one condition for the conditional handover or the at least one condition for the cell addition or change which was not met,N last measurements on the source cell,an indication indicating that a time to trigger timer of the at least one condition for the conditional handover or the at least one condition for the cell addition or change which was not met was running at the time when the connection failure with the third network node was detected.

7. An apparatus, comprising:at least one processor; andat least one memory storing instructions that, when executed by the at least one processor,cause the apparatus at least to:transmit, by a second network node to a first network node, at least one condition for a cell addition or change;receive from the first network node, a failure report indicating a connection failure taking place between a terminal device and a third network node when at least the at least one condition for the cell addition or change was not met; andcarry out one of the following:transmitting the failure report to an operations administration and maintenance entity, ordetermining adaptation information for the at least one condition for the cell addition or change.

8. The apparatus of claim 7, wherein the apparatus is configured to:transmit a failure report configuration to the first network node before receiving the failure report, the failure report configuration specifying at least one of the following:contents of the failure report; orcriteria for triggering the failure report.

9. The apparatus of claim 7 or 8, wherein the failure report further comprises at least one of the following:an identifier of a configuration comprising the at least one condition for the conditional handover and the at least one condition for the cell addition or change,the at least one condition for the cell addition or change,information of a target cell relating to the at least one condition for the cell addition or change,N last measurements on the target cell, N being a positive integer,information of a source cell relating to the at least one condition for the cell addition or change,N last measurements on the source cell, oran indication indicating that a time to trigger timer of the at least one condition for the celladdition or change was running at the time when the connection failure took place.

10. The apparatus of any of claims 7 to 9, wherein, in case the failure report is transmitted to the operations administration and maintenance entity, the apparatus is configured to:receive from the operations administration and maintenance entity, adaptation information for the at least one condition for the cell addition or change; andadapt the at least one condition for the cell addition or change based on the adaptation information.

11. An apparatus, comprising:at least one processor; andat least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to:transmit, by a first network node to a terminal device, a configuration message comprising at least one condition for a conditional handover and at least one condition for a cell addition or change;receive from the terminal device, a failure report indicating a connection failure taking place between the terminal device and a third network node when at least one of the at least one condition for the conditional handover and the at least one condition for the cell addition or change was not met; andcarry out one of the following:transmitting the failure report to an operations administration and maintenance entity,transmitting the failure report to a second network node which determined the at least one condition for the cell addition or change in case the at least one condition for the cell addition or change was not met, ordetermining adaptation information for the at least one condition for the conditional handover in case the at least one condition for the conditional handover was not met.

12. The apparatus of claim 11, wherein the apparatus is configured to:transmit to the terminal device, a failure report configuration specifying at least one of the following:contents of the failure report;criteria for triggering the failure report,the failure report configuration being determined by the first network node or received from the second network node.

13. The apparatus of claim 11 or 12, wherein, in case the failure report is transmitted to the operations administration and maintenance entity, the apparatus is configured to:receive from the operations administration and maintenance entity, adaptation information for the at least one condition for the conditional handover or the at least one condition for the cell addition or change which was not met; andin case the adaptation information is for the at least one condition for the cell addition or change which was not met,transmit the adaptation information to the second network node, orin case the adaptation information is for the at least one condition for the conditional handover which was not met,adapt the at least one condition for the conditional handover based on the adaptation information.

14. An apparatus, comprising:at least one processor; andat least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to:receive, by an operations administration and maintenance entity from a first network node or a second network device, a failure report indicating a connection failure taking place between a terminal device and a third network node when at least one of at least one condition for a conditional handover and at least one condition for a cell addition or change was not met;determine adaptation information for the at least one condition for the conditional handover or the at least one condition for the cell addition or change which was not met; and transmit the adaptation information tothe first network node in case the adaptation information is determined for the at least one condition for the conditional handover which was not met,the second network node in case the adaptation information is determined for the at least one condition for the cell addition or change which was not met, orthe first network node regardless of which of the at least one condition for the conditional handover and the at least one condition for the cell addition or change was not met, in case the failure report is received from the first network node.

15. A method, comprising:receiving, by a terminal device from a first network node, a configuration message comprising at least one condition for a conditional handover and at least one condition for a cell addition or change;evaluating whether the at least one condition for the conditional handover and the at least one condition for the cell addition or change are met;detecting a failure of a connection with a third network node before both of the at least one conditions are met; andtransmitting to the first network node, a failure report indicating the connection failure taking place before both of the at least one conditions were met.

16. The method of claim 15, further comprising:receiving from the first network node, a failure report configuration specifying at least one of the following:contents of the failure report; orcriteria for triggering the failure report.

17. A method, comprising:transmitting, by a second network node to a first network node, at least one condition for acell addition or change;receiving from the first network node, a failure report indicating a connection failure taking place between a terminal device and a third network node when at least one of at least one condition for a conditional handover and the at least one condition for the cell addition or change was not met; andcarrying out one of the following:transmitting the failure report to an operations administration and maintenance entity, ordetermining adaptation information for the at least one condition for the cell addition or change.

18. The method of claim 17, further comprising:transmitting a failure report configuration to the first network node before receiving the failure report, the failure report configuration specifying at least one of the following:contents of the failure report; orcriteria for triggering the failure report.

19. The method of claim 17 or 18, further comprising, in case the failure report is transmitted to the operations administration and maintenance entity:receiving from the operations administration and maintenance entity, adaptation information for the at least one condition for the cell addition or change; andadapting the at least one condition for the cell addition or change based on the adaptation information.

20. A method, comprising:transmitting, by a first network node to a terminal device, a configuration message comprising at least one condition for a conditional handover and at least one condition for a cell addition or change;receiving from the terminal device, a failure report indicating a connection failure taking place between the terminal device and a third network node when at least one of the at least onecondition for the conditional handover and the at least one condition for the cell addition or change was not met; andcarrying out one of the following:transmitting the failure report to an operations administration and maintenance entity,transmitting the failure report to a second network node which determined the at least one condition for the cell addition or change in case the at least one condition for the cell addition or change was not met, ordetermining adaptation information for the at least one condition for the conditional handover in case the at least one condition for the conditional handover was not met.

21. The method of claim 20, further comprising:transmitting to the terminal device, a failure report configuration specifying at least one of the following:contents of the failure report;criteria for triggering the failure report,the failure report configuration being determined by the first network node or received from the second network node.

22. The method of claim 20 or 21, further comprising, in case the failure report is transmitted to the operations administration and maintenance entity:receiving from the operations administration and maintenance entity, adaptation information for the at least one condition for the conditional handover or the at least one condition for the cell addition or change which was not met; andin case the adaptation information is for the at least one condition for the cell addition or change which was not met,transmitting the adaptation information to the second network node, orin case the adaptation information is for the at least one condition for the conditional handover which was not met,adapting the at least one condition for the conditional handover based on the adaptation information.

23. A method, comprising:receiving, by an operations administration and maintenance entity from a first network node or a second network device, a failure report indicating a connection failure taking place between a terminal device and a third network node when at least one of at least one condition for a conditional handover and at least one condition for a cell addition or change was not met;determining adaptation information for the at least one condition for the conditional handover or the at least one condition for the cell addition or change which was not met; andtransmitting the adaptation information tothe first network node in case the adaptation information is determined for the at least one condition for the conditional handover which was not met,the second network node in case the adaptation information is determined for the at least one condition for the cell addition or change which was not met, orthe first network node regardless of which of the at least one condition for the conditional handover and the at least one condition for the cell addition or change was not met, in case the failure report is received from the first network node.

24. An apparatus, comprising means for performing the method of any of claims 15 to 23.

25. A computer readable medium comprising instructions that, when executed by an apparatus, cause the apparatus to perform the method of any of claims 15 to 23.Application No: GB2405867.9Examiner:Contract Unit ExaminerClaims searched: 1-25Date of search: 10 December 2024Patents Act 1977: Search Report under Section 17Documents considered to be relevant:Category Relevant to claims Identity of document and passage or figure of particular relevance X Y X X Y A X: 1-6, 15, 16, 24,25 Y: H, 12, 20,21 1, 15, 24, 25 X; 1, 15, 24,25 Y: H,12, 20,21 US2023 / 007550 Al (KUMAR RAJEEV ET AL) paragraph [0093] - paragraph [0121], figure 3 US2023 / 300708 Al (LENG SHIYANG ET AL) paragraph [0066] - paragraph [0079] 3 GPP DRAFT, vol RAN WG3, 2024, DAPENG LI ET AL, "Discussion on MRO" URL: https: / / www.3 gpp, or g / ftp / TSGRAN / WG3_Iu / TSGR3_ 123-bis / Docs / R3-242021, zip section "3 MRO for CHO-CPAC" 3 GPP DRAFT, vol RAN WG3, 2024, MIAOQI ZHANG ET AL, "Discussion on MRO enhancements for RI 8 mobility features" URL: https: / / www.3gpp.org / ftp / TSG_RAN / WG3_Iu / TSGR3_123- bis / Docs / R3-241955.zip section "2.2 CHO with candidate SCG"Categories:X Document indicating lack of novelty or inventive step A Document indicating technological background and / or state of the art. Y Document indicating lack of inventive step if P Document published on or after the declared priority date but combined with one or more other documents of same category. before the filing date of this invention. & Member of the same patent family E Patent document published on or after, but with priority date earlier than, the filing date of this application.Field of Search:Search of GB, EP, WO &US patent documents classified in the following areas of the UKCX :Worldwide search of patent documents classified in the following areas of the IPC____________H04W____________________________________________The following online and other databases have been used in the preparation of this search reportInternational Classification:Subclass Subgroup Valid From H04W 0036 / 36 01 / 01 / 2009

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