Interruption time reduction during conditional handover

Abstract

Example embodiments of the present disclosure are related to solutions for interruption time reduction during conditional handover (CHO) with candidate secondary cell group (SCG) successful operations In a solution, a first apparatus determines that an elapsed time of a first timer is larger than a first threshold associated with a successful CHO with candidate SCG procedure. The first timer starts in response to a second condition for execution of conditional primary secondary cell addition or change (CPAC) is fulfilled and stops in response to a first condition for execution of CHO is fulfilled. The first apparatus then transmits, to a second apparatus, a first handover report indicating an interruption of a connection to a source secondary node. The successful primary secondary cell change report comprises information of a second timer associated with the connection.

Description

INTERRUPTION TIME REDUCTION DURING CONDITIONAL HANDOVERFIELD

[0001] Various example embodiments of the present disclosure generally relate to the field of telecommunication and in particular, to methods, devices, apparatuses and computer readable storage medium for interruption time reduction during conditional handover (CHO) with candidate secondary cell group (SCG) successful operations.BACKGROUND

[0002] A CHO with candidate secondary cell group(s) (SCG(s)) is defined as a primary cell (PCell) change with primary secondary cell (PSCell) addition / change that is executed by a user equipment (UE) when the execution conditions for both candidate PCell and the associated candidate PSCell are met. The UE starts evaluating the execution conditions for candidate PCell(s) and candidate PSCell(s) simultaneously upon receiving the CHO with candidate SCG(s) configuration, and stops evaluating the execution conditions once a PCell change or a PSCell change is triggered. The UE does not execute CHO with candidate SCG(s) until the execution conditions for both the candidate PCell and the associated candidate PSCell are met.SUMMARY

[0003] In a first aspect of the present disclosure, there is provided a first apparatus. The first apparatus comprises at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the first apparatus at least to: determine that an elapsed time of a first timer is larger than a first threshold associated with a successful conditional handover (CHO) with candidate secondary cell group (SCG) procedure, wherein the first timer starts in response to a first condition for execution of CHO is fulfilled and stops in response to a second condition for execution of conditional primary secondary cell (PSCell) addition or change (CP AC) is fulfilled; and transmit, to a second apparatus, a successful primary secondary cell change report indicating an interruption of a connection to a third apparatus, wherein the successful primary secondary cell change report comprises information of a second timer associatedwith the connection.

[0004] In a second aspect of the present disclosure, there is provided a second apparatus. The second apparatus comprises at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the second apparatus at least to: receive, from a first apparatus, a successful primary secondary cell change report indicating an interruption of a connection to a third apparatus, wherein the successful primary secondary cell change report comprises information of a second timer associated with the connection, and wherein an elapsed time of a first timer is larger than a first threshold associated with a successful conditional handover (CHO) with candidate secondary cell group (SCG) procedure, and the first timer starts in response to a first condition for execution of CHO is fulfilled and stops in response to a second condition for execution of conditional primary secondary cell (PSCell) addition or change (CP AC) is fulfilled.

[0005] In a third aspect of the present disclosure, there is provided a third apparatus. The third apparatus comprises at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the third apparatus at least to: transmit, to a first apparatus, at least one configuration regarding conditional handover (CHO) with candidate secondary cell group (SCG) configuration that comprises at least one of: at least a first condition for execution of CHO, and a second condition for execution of conditional primary secondary cell (PSCell) addition or change (CP AC), wherein the first apparatus is in an access procedure associated with the successful CHO with candidate SCG procedure.

[0006] In a fourth aspect of the present disclosure, there is provided an apparatus. The apparatus comprises at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the first apparatus at least to: determine that an elapsed time of a first timer is larger than a first threshold associated with a successful conditional handover (CHO) with candidate secondary cell group (SCG) procedure, wherein the first timer starts in response to a second condition for execution of conditional primary secondary cell (PSCell) addition or change (CP AC) is fulfilled and stops in response to a first condition for execution of CHO is fulfilled; and transmit, to a second apparatus, a successful handover report indicating an interruption of a connection to a source secondary node, wherein the successful handover report comprisesinformation of a second timer associated with the connection..

[0007] In a fifth aspect of the present disclosure, there is provided an apparatus. The apparatus comprises at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the second apparatus at least to: receive, from a first apparatus, a successful handover report indicating an interruption of a connection to a source secondary node, wherein the successful handover report comprises information of a second timer associated with the connection, and wherein an elapsed time of a first timer is larger than a first threshold associated with the successful conditional handover (CHO) with candidate secondary cell group (SCG) procedure, and the first timer starts in response to a second condition for execution of conditional primary secondary cell (PSCell) addition or change (CP AC) is fulfilled and stops in response to a first condition for execution of CHO is fulfilled.

[0008] In a sixth aspect of the present disclosure, there is provided a method. The method comprises: determining that an elapsed time of a first timer is larger than a first threshold associated with a successful conditional handover (CHO) with candidate secondary cell group (SCG) procedure, wherein the first timer starts in response to a first condition for execution of CHO is fulfilled and stops in response to a second condition for execution of conditional primary secondary cell (PSCell) addition or change (CP AC) is fulfilled; and transmitting, to a second apparatus, a successful primary secondary cell change report indicating an interruption of a connection to a third apparatus, wherein the successful primary secondary cell change report comprises information of a second timer associated with the connection.

[0009] In a seventh aspect of the present disclosure, there is provided a method. The method comprises: receiving, from a first apparatus, a successful primary secondary cell change report indicating an interruption of a connection to a third apparatus, wherein the successful primary secondary cell change report comprises information of a second timer associated with the connection, and wherein an elapsed time of a first timer is larger than a first threshold associated with a successful conditional handover (CHO) with candidate secondary cell group (SCG) procedure, and the first timer starts in response to a first condition for execution of CHO is fulfilled and stops in response to a second condition for execution of conditional primary secondary cell (PSCell) addition or change (CP AC) is fulfilled.

[0010] In an eighth aspect of the present disclosure, there is provided a method. The method comprises: transmitting, to a first apparatus, at least one configuration regarding conditional handover (CHO) with candidate secondary cell group (SCG) configuration that comprises at least one of at least a first condition for execution of CHO, and a second condition for execution of conditional primary secondary cell (PSCell) addition or change (CPAC), wherein the first apparatus is in an access procedure associated with the successful CHO with candidate SCG procedure.

[0011] In a ninth aspect of the present disclosure, there is provided a method. The method comprises: determining that an elapsed time of a first timer is larger than a first threshold associated with a successful conditional handover (CHO) with candidate secondary cell group (SCG) procedure, wherein the first timer starts in response to a second condition for execution of conditional primary secondary cell (PSCell) addition or change (CPAC) is fulfilled and stops in response to a first condition for execution of CHO is fulfilled; and transmitting, to a second apparatus, a successful handover report indicating an interruption of a connection to a source secondary node, wherein the successful handover report comprises information of a second timer associated with the connection.

[0012] In a tenth aspect of the present disclosure, there is provided a method. The method comprises: receiving, from a first apparatus, a successful handover report indicating an interruption of a connection to a source secondary node, wherein the successful handover report comprises information of a second timer associated with the connection, and wherein an elapsed time of a first timer is larger than a first threshold associated with the successful conditional handover (CHO) with candidate secondary cell group (SCG) procedure, and the first timer starts in response to a second condition for execution of conditional primary secondary cell (PSCell) addition or change (CPAC) is fulfilled and stops in response to a first condition for execution of CHO is fulfilled.

[0013] In an eleventh aspect of the present disclosure, there is provided a first apparatus. The first apparatus comprises means for determining that an elapsed time of a first timer is larger than a first threshold associated with a successful conditional handover (CHO) with candidate secondary cell group (SCG) procedure, wherein the first timer starts in response to a first condition for execution of CHO is fulfilled and stops in response to a second condition for execution of conditional primary secondary cell (PSCell) additionor change (CP AC) is fulfilled; and means for transmitting, to a second apparatus, a successful primary secondary cell change report indicating an interruption of a connection to a third apparatus, wherein the successful primary secondary cell change report comprises information of a second timer associated with the connection.

[0014] In a twelfth aspect of the present disclosure, there is provided a second apparatus. The second apparatus comprises means for receiving, from a first apparatus, a successful primary secondary cell change report indicating an interruption of a connection to a third apparatus, wherein the successful primary secondary cell change report comprises information of a second timer associated with the connection, and wherein an elapsed time of a first timer is larger than a first threshold associated with a successful conditional handover (CHO) with candidate secondary cell group (SCG) procedure, and the first timer starts in response to a first condition for execution of CHO is fulfilled and stops in response to a second condition for execution of conditional primary secondary cell (PSCell) addition or change (CP AC) is fulfilled.

[0015] In a thirteenth aspect of the present disclosure, there is provided a third apparatus. The third apparatus comprises means for transmitting, to a first apparatus, at least one configuration regarding conditional handover (CHO) with candidate secondary cell group (SCG) configuration that comprises at least one of at least a first condition for execution of CHO, and a second condition for execution of conditional primary secondary cell (PSCell) addition or change (CP AC), wherein the first apparatus is in an access procedure associated with the successful CHO with candidate SCG procedure.

[0016] In a fourteenth aspect of the present disclosure, there is provided a first apparatus. The first apparatus comprises means for determining that an elapsed time of a first timer is larger than a first threshold associated with a successful conditional handover (CHO) with candidate secondary cell group (SCG) procedure, wherein the first timer starts in response to a second condition for execution of conditional primary secondary cell (PSCell) addition or change (CP AC) is fulfilled and stops in response to a first condition for execution of CHO is fulfilled; and means for transmitting, to a second apparatus, a successful handover report indicating an interruption of a connection to a source secondary node, wherein the successful handover report comprises information of a second timer associated with the connection.

[0017] In a fifteenth aspect of the present disclosure, there is provided a secondapparatus. The second apparatus comprises means for receiving, from a first apparatus, a successful handover report indicating an interruption of a connection to a source secondary node, wherein the successful handover report comprises information of a second timer associated with the connection, and wherein an elapsed time of a first timer is larger than a first threshold associated with the successful conditional handover (CHO) with candidate secondary cell group (SCG) procedure, and the first timer starts in response to a second condition for execution of conditional primary secondary cell (PSCell) addition or change (CP AC) is fulfilled and stops in response to a first condition for execution of CHO is fulfilled.

[0018] In a sixteenth aspect of the present disclosure, there is provided a computer readable medium. The computer readable medium comprises instructions stored thereon for causing an apparatus to perform at least the method according to the sixth aspect.

[0019] In a seventeenth aspect of the present disclosure, there is provided a computer readable medium. The computer readable medium comprises instructions stored thereon for causing an apparatus to perform at least the method according to the seventh aspect.

[0020] In an eighteenth aspect of the present disclosure, there is provided a computer readable medium. The computer readable medium comprises instructions stored thereon for causing an apparatus to perform at least the method according to the eighth aspect.

[0021] In a nineteenth aspect of the present disclosure, there is provided a computer readable medium. The computer readable medium comprises instructions stored thereon for causing an apparatus to perform at least the method according to the ninth aspect.

[0022] In a twentieth aspect of the present disclosure, there is provided a computer readable medium. The computer readable medium comprises instructions stored thereon for causing an apparatus to perform at least the method according to the tenth aspect.

[0023] It is to be understood that the Summary section is not intended to identify key or essential features of embodiments of the present disclosure, nor is it intended to be used to limit the scope of the present disclosure. Other features of the present disclosure will become easily comprehensible through the following description.BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Some example embodiments will now be described with reference to the accompanying drawings, where:

[0025] FIG. 1 illustrates an example communication environment in which example embodiments of the present disclosure can be implemented;

[0026] FIG. 2A illustrates a schematic diagram of a scenario in which CP AC conditions are met first and CHO conditions are met later;

[0027] FIG. 2B illustrates a schematic diagram of another scenario in which CHO conditions are met first and CP AC conditions are met later;

[0028] FIG. 3 A illustrates a signaling flow of a process of interruption time reduction according to some example embodiments of the present disclosure;

[0029] FIG. 3B illustrates a signaling flow of another process of interruption time reduction according to some example embodiments of the present disclosure;

[0030] FIG. 4 illustrates a schematic diagram of an example of successful execution of CHO with candidate SCG(s) according to some example embodiments of the present disclosure;

[0031] FIG. 5 illustrates a schematic diagram of an example of possible near failure reporting after successful execution of CHO with candidate SCG(s) according to some example embodiments of the present disclosure;

[0032] FIG. 6 illustrates a schematic diagram of an example of optimization of the CHO conditions for the CHO with candidate SCG(s) according to some example embodiments of the present disclosure;

[0033] FIG. 7 illustrates a schematic diagram of an example of successful execution of the CHO with candidate SCG(s) after the CHO optimization according to some example embodiments of the present disclosure;

[0034] FIG. 8 illustrates a flowchart of a method implemented at a first apparatus according to some example embodiments of the present disclosure;

[0035] FIG. 9 illustrates a flowchart of a method implemented at a second apparatus according to some example embodiments of the present disclosure;

[0036] FIG. 10 illustrates a flowchart of a method implemented at a third apparatus according to some example embodiments of the present disclosure;

[0037] FIG. 11 illustrates a flowchart of a method implemented at a first apparatusaccording to some example embodiments of the present disclosure;

[0038] FIG. 12 illustrates a flowchart of a method implemented at a second apparatus according to some example embodiments of the present disclosure;

[0039] FIG. 13 illustrates a simplified block diagram of a device that is suitable for implementing example embodiments of the present disclosure; and

[0040] FIG. 14 illustrates a block diagram of an example computer readable medium in accordance with some example embodiments of the present disclosure.

[0041] Throughout the drawings, the same or similar reference numerals represent the same or similar element.DETAILED DESCRIPTION

[0042] Principle of the present disclosure will now be described with reference to some example embodiments. It is to be understood that these embodiments are described only for the purpose of illustration and help those skilled in the art to understand and implement the present disclosure, without suggesting any limitation as to the scope of the disclosure. Embodiments described herein can be implemented in various manners other than the ones described below.

[0043] In the following description and claims, unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skills in the art to which this disclosure belongs.

[0044] References in the present disclosure to “one embodiment,” “an embodiment,” “an example embodiment,” and the like indicate that the embodiment described may include a particular feature, structure, or characteristic, but it is not necessary that every embodiment includes the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is submitted that it is within the knowledge of one skilled in the art to affect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described.

[0045] It shall be understood that although the terms “first,” “second,”..., etc. in front of noun(s) and the like may be used herein to describe various elements, these elementsshould not be limited by these terms. These terms are only used to distinguish one element from another and they do not limit the order of the noun(s). For example, a first element could be termed a second element, and similarly, a second element could be termed a first element, without departing from the scope of example embodiments. As used herein, the term “and / or” includes any and all combinations of one or more of the listed terms.

[0046] 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 “or”, mean at least any one of the elements, or at least any two or more of the elements, or at least all the elements.

[0047] As used herein, unless stated explicitly, performing a step “in response to A” does not indicate that the step is performed immediately after “A” occurs and one or more intervening steps may be included.

[0048] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises”, “comprising”, “has”, “having”, “includes” and / or “including”, when used herein, specify the presence of stated features, elements, and / or components etc., but do not preclude the presence or addition of one or more other features, elements, components and / or combinations thereof.

[0049] As used in this application, the term “circuitry” may refer to one or more or all of the following:(a) hardware-only circuit implementations (such as implementations in only analog and / or digital circuitry) and(b) combinations of hardware circuits and software, such as (as applicable):(i) a combination of analog and / or digital hardware circuit(s) with software / firmware and(ii) any portions of hardware processor(s) with software (including digital signal processor(s)), software, and memory(ies) that work together to cause an apparatus, such as a mobile phone or server, to perform various functions) and(c) hardware circuit(s) and or processor(s), such as a microprocessor(s) or a portion of a microprocessor(s), that requires software (e.g., firmware) for operation, but the software may not be present when it is not needed for operation.

[0050] This definition of circuitry applies to all uses of this term in this application, including in any claims. As a further example, as used in this application, the term circuitry also covers an implementation of merely a hardware circuit or processor (or multiple processors) or portion of a hardware circuit or processor and its (or their) accompanying software and / or firmware. The term circuitry also covers, for example and if applicable to the particular claim element, a baseband integrated circuit or processor integrated circuit for a mobile device or a similar integrated circuit in server, a cellular network device, or other computing or network device.

[0051] As used herein, the term “communication network” refers to a network following any suitable communication standards, such as New Radio (NR), Long Term Evolution (LTE), LTE-Advanced (LTE-A), Wideband Code Division Multiple Access (WCDMA), High-Speed Packet Access (HSPA), Narrow Band Internet of Things (NB- loT) and so on. Furthermore, the communications between a terminal device and a network device in the communication network may be performed according to any suitable generation communication protocols, including, but not limited to, the first generation (1G), the second generation (2G), 2.5G, 2.75G, the third generation (3G), the fourth generation (4G), 4.5G, the fifth generation (5G), the sixth generation (6G) communication protocols, and / or any other protocols either currently known or to be developed in the future. Embodiments of the present disclosure may be applied in various communication systems. Given the rapid development in communications, there will of course also be future type communication technologies and systems with which the present disclosure may be embodied. It should not be seen as limiting the scope of the present disclosure to only the aforementioned system.

[0052] As used herein, the term “network device” refers to a node in a communication network via which a terminal device accesses the network and receives services therefrom. The network device may refer to a base station (BS) or an access point (AP), for example, a node B (NodeB or NB), an evolved NodeB (eNodeB or eNB), an NR NB (also referred to as a gNB), a Remote Radio Unit (RRU), a radio header (RH), a remote radio head(RRH), a relay, an Integrated Access and Backhaul (IAB) node, a low power node such as a femto, a pico, a non-terrestrial network (NTN) or non-ground network device such as a satellite network device, a low earth orbit (LEO) satellite and a geosynchronous earth orbit (GEO) satellite, an aircraft network device, and so forth, depending on the applied terminology and technology. In some example embodiments, radio access network (RAN) split architecture comprises a Centralized Unit (CU) and a Distributed Unit (DU) at an IAB donor node. An IAB node comprises a Mobile Terminal (IAB-MT) part that behaves like a UE toward the parent node, and a DU part of an IAB node behaves like a base station toward the next-hop IAB node.

[0053] The term “terminal device” refers to any end device that may be capable of wireless communication. By way of example rather than limitation, a terminal device may also be referred to as a communication device, user equipment (UE), a Subscriber Station (SS), a Portable Subscriber Station, a Mobile Station (MS), or an Access Terminal (AT). The terminal device may include, but not limited to, a mobile phone, a cellular phone, a smart phone, voice over IP (VoIP) phones, wireless local loop phones, a tablet, a wearable terminal device, a personal digital assistant (PDA), portable computers, desktop computer, image capture terminal devices such as digital cameras, gaming terminal devices, music storage and playback appliances, vehicle-mounted wireless terminal devices, wireless endpoints, mobile stations, laptop-embedded equipment (LEE), laptop-mounted equipment (LME), USB dongles, smart devices, wireless customer-premises equipment (CPE), an Internet of Things (loT) device, a watch or other wearable, a head-mounted display (HMD), a vehicle, a drone, a medical device and applications (e.g., remote surgery), an industrial device and applications (e.g., a robot and / or other wireless devices operating in an industrial and / or an automated processing chain contexts), a consumer electronics device, a device operating on commercial and / or industrial wireless networks, and the like. The terminal device may also correspond to a Mobile Termination (MT) part of an IAB node (e.g., a relay node). In the following description, the terms “terminal device”, “communication device”, “terminal”, “user equipment” and “UE” may be used interchangeably.

[0054] As used herein, the term “resource,” “transmission resource,” “resource block,” “physical resource block” (PRB), “uplink resource,” or “downlink resource” may refer to any resource for performing a communication, for example, a communication between a terminal device and a network device, such as a resource in time domain, a resource infrequency domain, a resource in space domain, a resource in code domain, or any other combination of the time, frequency, space and / or code domain resource enabling a communication, and the like. In the following, unless explicitly stated, a resource in both frequency domain and time domain will be used as an example of a transmission resource for describing some example embodiments of the present disclosure. It is noted that example embodiments of the present disclosure are equally applicable to other resources in other domains.

[0055] FIG. 1 shows an example communication environment 100 in which example embodiments of the present disclosure can be implemented. In the communication environment 100, a first apparatus 110 may communicate with a third apparatus 130 as well as a second apparatus 120, for example, in a Dual Connectivity (DC). The third apparatus 130 may communicate with the second apparatus 120 (such as, via X2 or Xn interface).

[0056] Dual Connectivity (DC) is a mode of operation where a terminal device (for example, user equipment, UE) nay be configured to utilize radio resources provided by two network devices, for example, two base stations (BSs). One network device serves the terminal device as a Master Node (MN), and the other network device serves the terminal device as a Secondary Node (SN). In a DC scenario, the MN and SN may be associated with one or more serving cells usually, and further a carrier aggregation (CA) technology could be implemented for efficient frequency usage. The group of serving cells associated with the MN is referred to as a Master Cell Group (MCG) and the group of serving cells associated with the SN is referred to as a Secondary Cell Group (SCG).

[0057] In the example of FIG. 1, during a CHO, the third apparatus 130 acts as a source MN of the first apparatus 110, while the second apparatus 120 acts as a target MN of the first apparatus 110. The serving areas of the third apparatus 130 and the second apparatus 120 are called as cells. As shown in FIG. 1, a group of cells of the third apparatus 130 includes a primary cell (PCell) 150-1 and an additional secondary cell (SCell) 150-2. Since the third apparatus 130 serves as the source MN, the group of cells of the third apparatus 130 is referred to as MCG 150. A group of cells of the second apparatus 120 includes a primary cell 160-1 and an additional secondary cell 160-2. In this example, the second apparatus 120 may act as the SN, thus the group of cells of the second apparatus 120 is referred to as SCG 160 and the primary cell 160-1 is also referred to asPSCell 160-1.

[0058] Communications between the first apparatus 110, the third apparatus 130 and the second apparatus 120 may be implemented according to any proper communication protocol(s). Communication in a direction from a first apparatus 110 towards the third apparatus 130 or the second apparatus 120 is referred to as UL communication, while communication in a reverse direction from the third apparatus 130 or the second apparatus 120 towards the first apparatus 110 is referred to as DL communication. The first apparatus 110 may move across the coverage areas of the third apparatus 130, the second apparatus 120 and possibly other network devices.

[0059] In the UL communication, the first apparatus 110 may transmit UL data and control information via a UL channel. In some examples embodiments, the UL data may be transmitted in a physical uplink shared channel (PUSCH) and / or any other UL channels that are available used for data transmission. In the DL transmission, the third apparatus 130 or the second apparatus 120 may transmit DL data and control information to the first apparatus 110 via a DL channel. In some examples, the DL data may be transmitted in a physical downlink shared channel (PDSCH) and / or any other DL channels that are available used for data transmission.

[0060] The DC provided by the third apparatus 130 and the second network 120 may comprise any suitable type of Multi-Radio Dual Connectivity (MR-DC), including but not limited to E-UTRA (Evolved Universal Terrestrial Radio Access)-NR Dual Connectivity (EN-DC), NGEN-DC, NE-DC and NR-DC. In the case of EN-DC, the third apparatus 130 is an eNB and the second apparatus 120 is a gNB. In the case of NGEN- DC, the third apparatus 130 is a gNB and the second apparatus 120 is an eNB. In the case of NR-DC, the network devices 130 and 120 are both gNBs.

[0061] In some example embodiments, a CHO with candidate SCGs procedure may be performed in the environment 100. In this procedure, the first apparatus 110 may handover, for example, from the primary cell (PCell) 150-1 and the secondary cell (SCell) 150-2 to the primary cell 160-1 and the secondary cell 160-2. More details in this regard will be discussed with reference to FIGS. 2A to 12.

[0062] It should be appreciated that the number of SCells in FIG. 1 is given for the purpose of illustration without suggesting any limitations to the present disclosure. In some other embodiments, the third apparatus 130 and the second apparatus 120 mayprovide any suitable number of SCells for serving the first apparatus 110.

[0063] It should be appreciated that the number and type of devices in FIG. 1 are given for the purpose of illustration without suggesting any limitations to the present disclosure. The communication environment 100 may include any suitable number of network devices and / or terminal devices adapted for implementing implementations of the present disclosure. Further, the communication environment 100 may include any other devices than the network devices and the terminal devices, such as a core network element, but they are omitted here so as to avoid obscuring the present invention.

[0064] Although a handover (HO) from one cell to another may be successful, there may still be outages during the handover (e.g., T310 timer may start but may not expire before HO complete) and it may still be possible to further optimize the timing of the handovers. Successful Handover Report (SHR) was discussed for that reason.

[0065] SHR may be configured by both a source node and a target node. They are different nodes configuring different parts of SHR) during handover (SHR configuration is within handover command), and is fetched by the target node and forwarded back to the source node, if needed, using UEInformationRequest / UEInformationResponse. The UE includes the availability of SHR to the network in each complete message sent in RRC procedure, i.e., RRCReconfigurationComplete, RRCReestablishmentComplete, RRCSetupComplete, RRCResumeComplete message, if it has available successful HO report to be reported. The UE may discard the SHR, i.e., release the UE variable VarSuccHO-Report, 48 hours after the SHR is stored.

[0066] The UE only logs SHR, if SHR configuration is received previous to the handover and at least one of the following criteria is satisfied:T310 timer of the UE exceeds the configured threshold by the source node,T312 timer of the UE exceeds the configured threshold by the source node,T304 timer of the UE exceeds the configured threshold by the target node.

[0067] There are separate (potentially in parallel) configurable thresholds for T310 / T312 / T304 timers, and those can be percentage values of 40%, 60%, 80%. The percentage is to indicate the ratio of the threshold value (unit: ms) over the signalled T310 / T312 / T304 timer value (unit: ms). For threshold for T312 timer, the percentage value also includes 20%.

[0068] The content of SHR may include:Source and target cell identifications (IDs) of the handover,Location information,Latest radio link measurements of all measurement IDs available at the time handover is executed for all handover types,A cause that was the trigger for generating the SHR, i.e., t310-cause, t312-cause, t304-cause,Latest radio measurement results of the candidate target cells in case of conditional HO,Time elapsed between conditional HO execution towards target cell and corresponding latest configuration received for the selected target cell, cell-radio network temporary identifier (C-RNTI) of target cell,RA-InformationCommon when T304 is above a threshold,In case of dual active protocol stack (DAPS) HO, an indication that the source cell failed previously to being release and the introduced interruption time are also logged.

[0069] Similarly, a SPR (a.k.a. Successful Pscell Addition or Change report) was then introduced to log near failures related to Pscell additions and change. The design is very similar to that of SHR, in terms of configuration, triggering thresholds and UE behavior.

[0070] SPR configuration is sent within RRC Connection Reconfiguration message to UE. Both S_MN (source master node) and S_SN (source secondary Node) are allowed to configure SPR for the UE if initiating the PScell change. The SPR is fetched by the receiving MN node using UEInformationRequest / UEInformationResponse procedure. In case receiving MN is different than initiating MN (which triggered the PSCell change) it is forwarded back to initiating MN node, by the ACCESS AND MOBILITY INDICATION message. If the UE has available SPR to be reported, it includes the “successHO-InfoAvailable” IE indicating the availability of SPR to the network in RRC Reconfiguration Complete message, i.e., RRCReconfigurationComplete, or RRCReestablishmentComplete, or RRCSetupComplete, or RRCResumeComplete message. The UE may discard the SPR, i.e., release the UE variable VarSuccHO-Report,48 hours after the SPR is stored.

[0071] UE only logs SPR if configuration of SPR is received and at least one of the following criteria is satisfied:• T310 timer of the UE exceeds the configured threshold by the source node,• T312 timer of the UE exceeds the configured threshold by the source node,• T304 timer of the UE exceeds the configured threshold by the target node.

[0072] There are separate (potentially in parallel) configurable thresholds for T310 / T312 / T304 timers, and those can be percentage values of 40%, 60%, 80%. For threshold for T312 timer, the percentage value also includes 20%. The percentage is to indicate the ratio of the threshold value (unit: ms) over the signalled T310 / T312 / T304 timer value (unit: ms).

[0073] The currently agreed content of SPR includes:• Source and target cell IDs of the PSCell change,• Latest radio link measurements of all measurement IDs available at the time PSCell change is executed for all handover types (including Conditional PSCell Change (CPC)),• A cause that was the trigger for generating the SPCR, i.e., t310-cause, t312-cause, t304-cause,• Latest radio measurement results of the candidate target cells in case of conditional PSCell change (CPC),• Time elapsed between CPC execution towards target cell and corresponding latest configuration received for the selected target cell,• RA-InformationCommon when T304 is above a threshold,• Available location information,• CGI of PCell,• Indication of whether PSCell change is MN-initiated or SN-initiated.

[0074] Even though the time between the two conditions (the CHO condition and the Conditional PSCell Addition or Change (CP AC) condition) being fulfilled and thus completion of the handover may be large (depending on configuration parameters andradio conditions, it may still not indicate a clear problem to be solved to the operator. Moreover, it is unclear which parameters of which execution condition should be updated (the CHO condition, the CP AC condition or even both).

[0075] However, if T310 is started on the link that first fulfilled the execution condition, while waiting on the second condition to trigger, this clearly introduces service interruption for the user and indicates more clearly to the operator which execution condition is at fault and which corrective actions are needed.

[0076] Even though the time between the two conditions being fulfilled and thus completion of the handover may be large (depending on configuration parameters and radio conditions) it may still not indicate a clear problem to be solved to the operator.

[0077] However, if T310 timer is started on the link that first fulfilled the execution condition, while waiting on the second execution condition to trigger, this clearly introduces service interruption for the user and indicates more clearly to the operator which execution condition is at fault and which corrective actions are needed. The problem to be solved is illustrated in FIG. 2A. FIG. 2A illustrates a schematic diagram 200A of a scenario (referred to as Scenario 1 hereafter) in which CP AC conditions are met first and CHO conditions are met later.

[0078] In FIG. 2A, it is considered that a UE is connected to PCell 1 and PSCell 1. The UE is configured with CHO with candidate SCG(s) configuration PCell 2 and PSCell 2. Furthermore, the UE may start evaluating the execution conditions of candidate PCell 2 and PSCell 2 simultaneously.

[0079] In Scenario 1, some time after configuration, conditional PSCell change (CPC) execution condition(s) of the candidate PSCell 2 are fulfilled first and then with some delay also the CHO execution condition(s) for candidate PCell 2 are fulfilled. During the wating for fulfilment of the CHO execution condition(s), the T310 timer on SCG of PSCell 1 is started. Depending on how long it takes to successfully complete the handover, the elapsed T310 timer may be above the configured T310 timer threshold to trigger the generation of SPR based on legacy mechanisms. This case is applicable only for CPC, not for conditional PSCell addition (CPA).

[0080] FIG. 2B illustrates a schematic diagram 200B of another scenario (referred to as Scenario 2 hereafter) in which CHO conditions are met first and CP AC conditions aremet later.

[0081] In Scenario 2, the CHO execution condition(s) of the candidate PCell 2 are fulfilled first and then with some delay also the CPC execution condition(s) for candidate PSCell 2 are also fulfilled. During the wating for fulfilment of the CP AC execution conditions the T310 timer on MCG of PCell 1 is started. Depending on how long it takes to successfully complete the handover, the elapsed T310 timer may be above the configured T310 threshold to trigger the generation of SHR based on legacy mechanisms. This case is applicable also for CPA.

[0082] Please note that scenarios where T310 timer on either leg is started before the corresponding execution condition is fulfilled (i.e. T310 timer on MCG started before CHO condition is fulfilled and / or T310 timer on SCG is started before the CP AC execution condition is fulfilled) are excluded as these clearly indicate an issue that can be solved by legacy CHO / CP AC optimization mechanisms. In the context of CHO / candidate SCGs, only the cases where the waiting on the fulfillment of the execution condition on one leg leads to the start of the T310 timer on the opposite leg are of interest.

[0083] Example embodiments of the present disclosure provide solutions for interruption time reduction during CHO with candidate SCG successful operations. The proposed solutions involve an enhancement of SHR / SPR reports to include information regarding a timer (e.g., T310 timer) elapsed time, i.e. SHR will include elapsed timer running on SCG leg while waiting for CHO condition to be fulfilled and SPR will include elapsed timer running on the MCG leg while waiting for CP AC condition to be fulfilled. This additional information will indicate clearly to the operator which corrective actions need to be taken.

[0084] FIG. 3A illustrates a signaling flow 300A of a process of interruption time reduction according to some example embodiments of the present disclosure. For the purposes of discussion, the signaling flow 300A will be discussed with reference to FIG. 1, for example, by using the first apparatus 110, the second apparatus 120 and the third apparatus 130. In some example embodiments, the first apparatus 110 may be discussed with a terminal device, e.g., a UE, the second apparatus 120 may be discussed with a target master node (target MN), e.g., a network device such as a BS or gNB, and the third apparatus 130 may be discussed with a source master node (source MN), e.g., another network device such as a BS or gNB.

[0085] In the signaling flow 300A, the first apparatus 110 determines (316) that an elapsed time of a first timer is larger than a first threshold associated with a successful CHO with candidate SCG procedure. The first timer starts in response to a first condition for execution of CHO is fulfilled and stops in response to a second condition for execution of CP AC is fulfilled.

[0086] Based on this determination (316), the first apparatus 110 transmits (318) to the second apparatus 120 (that is, the target MN), a successful primary secondary cell change report indicating an interruption of a connection to the third apparatus 130 (that is, the source MN). The successful primary secondary cell change report comprises information of a second timer associated with the connection. The second timer may be implemented with various timers which include, but not limited to, the T310 timer, the T312 timer, and / or the like.

[0087] In some example embodiments, the information of the second timer may include, for example, an elapsed time of the second timer or an indication indicting the second timer was started for the connection, and / or other related or suitable information. In some further example embodiments, the information of the second timer may indicate that the second timer was started after the first condition is fulfilled and is running while waiting for the second condition to be fulfilled.

[0088] Thus, the second apparatus 120 receives (320), from the first apparatus 110, the successful primary secondary cell change report indicating an interruption of a connection to the third apparatus 130. In some example embodiments, the second apparatus 120 may transmit (322) the successful primary secondary cell change report to the third apparatus 130. Upon receiving (324) the successful primary secondary cell change report from the second apparatus 120, the third apparatus 130 may know the CP AC is successful and the interruption of the connection.

[0089] Optionally, in some example embodiments, the third apparatus 130 transmits (312), to the first apparatus 110, at least one configuration regarding CHO with candidate SCG configuration. The at least one configuration may include, for example, but not limited to, a first condition for execution of CHO, and / or a second condition for execution of CP AC, and / or the like. In this case, the first apparatus 110 is in an access procedure associated with the successful CHO with candidate SCG procedure.

[0090] Correspondingly, the first apparatus 110 may receive (314), from the thirdapparatus 130, the at least one configuration regarding CHO with candidate SCG.

[0091] In addition to the above examples, in some example implementations, the at least one configuration may further include a second threshold for the second timer. With the second threshold, the first apparatus 110 may compare an elapsed value of the second timer with this second threshold, so as to transmit a successful primary secondary cell change report comprising information of the second timer based on the comparison.

[0092] In some example embodiments, the first apparatus 110 may start the second timer in response to detecting the interruption.

[0093] In some example embodiments, if the second timer was started after the first condition is fulfilled and is running while waiting for the second condition to be fulfilled, the first apparatus 110 may transmit the successful primary secondary cell change report comprising the information of the second timer.

[0094] Alternatively, or in addition, in some example embodiments, if an elapsed value of the second timer is larger than a second threshold, the first apparatus 110 may transmit the successful primary secondary cell change report comprising the information of the second timer.

[0095] Optionally, the first apparatus 110 may transmit a successful handover report to the second apparatus 120. In some example embodiments, the successful handover report may include an indication (for example, a flag) indicating if the second timer was started after the first condition is fulfilled and is running waiting for the second condition to be fulfilled.

[0096] As to the second apparatus 120, it may receive the successful handover report from the first apparatus 110. Optionally, the second apparatus 120 may forward the successful handover report to the third apparatus 130. Thus, the third apparatus 130 may receive the successful handover report from the second apparatus 120. In addition, or alternatively, the third apparatus 130 may receive the successful primary secondary cell change report from the second apparatus 120.

[0097] Referring back to FIG. 2B which corresponds to Scenario 2. In the cases discussed with reference to FIG. 2B, it is assumed that CHO condition is fulfilled first, a T310 timer started on MCG, and the CPC condition is fulfilled later.

[0098] In this scenario, the first apparatus 110 (e.g., a UE) may generate SPR if thetime between fulfillment of the two conditions is larger than a threshold. The UE may additionally include, in the SPR, a portion of time T310 was running on MCG while waiting for CP AC condition to be fulfilled. The inclusion of this new information element may be always done (UE hard coded) or simple inclusion or based on a network configured threshold (e.g only included if elapsed time > threshold). If SHR is also generated based on legacy 3GPP defined triggers ,i.e. elapsed T310 on MCG > Threshold, a new flag may be included, indicating if T310 started while waiting for the CP AC condition to be fulfilled.

[0099] An example of how the network may use this new information for deducing the necessary corrective action is provided below. If the SHR is reported, and if the flag is present, then the SHR is discarded. Otherwise, if T310 timer was started earlier than CHO condition is fulfilled, then the CHO execution condition may be tuned. Based on information in the SPR, the CP AC execution condition may be tuned to trigger CP AC earlier.

[0100] In view of the above, the issue discussed with reference to the Scenario 2 can be solved. Specifically, by involving an enhancement of SHR report to include information regarding a second timer (e.g., T310 timer), the interruption time during CHO with candidate SCG successful operations can be reduced.

[0101] FIG. 3B illustrates a signaling flow 300B of another process of interruption time reduction according to some example embodiments of the present disclosure. For the purposes of discussion, the signaling flow 300B will be discussed with reference to FIG. 1, for example, by using the first apparatus 110, the second apparatus 120 and the third apparatus 130. In some example embodiments, the first apparatus 110 may be discussed with a terminal device, e.g., a UE, the second apparatus 120 may be discussed with a target master node (target MN), e.g., a network device such as a BS or gNB, and the third apparatus may be discussed with a source master node, e.g., another network device such as a BS or gNB.

[0102] In the signaling flow 300B, the first apparatus 110 determines (366) that an elapsed time of a first timer is larger than a first threshold associated with a successful CHO with candidate SCG procedure. The first timer starts in response to a second condition for execution of CP AC is fulfilled and stops in response to a first condition for execution of CHO is fulfilled.

[0103] Based on this determination (366), the first apparatus 110 transmits (368) to the second apparatus 120 (that is, the target MN), a successful handover report indicating an interruption of a connection to a source secondary node (source SN). The successful handover report includes information of a second timer associated with the connection. The second timer may be implemented with various timers which include, but not limited to, the T310 timer, the T312 timer, and / or the like.

[0104] In some example embodiments, the information of the second timer may include, for example, an elapsed time of the second timer or an indication indicting the second timer was started for the connection, and / or other related or suitable information. In some further example embodiments, the information of the second timer may indicate that the second timer was started after the first condition is fulfilled and is running while waiting for the second condition to be fulfilled.

[0105] The second apparatus 120 receives (370), from the first apparatus 110, the successful handover report indicating an interruption of a connection to a source secondary node. In some example embodiments, the second apparatus 120 may transmit (372) the successful handover report to the third apparatus 130. Upon receiving (374) the successful handover report from the second apparatus 120, the third apparatus 130 may know the CHO is successful and the interruption of the connection.

[0106] Optionally, in some example embodiments, the third apparatus 130 transmits (362), to the first apparatus 110, at least one configuration regarding CHO with candidate SCG configuration. The at least one configuration may include, for example, but not limited to, a first condition for execution of CHO, and / or a second condition for execution of CP AC, and / or the like. In this case, the first apparatus 110 is in an access procedure associated with the successful CHO with candidate SCG procedure.

[0107] Correspondingly, the first apparatus 110 may receive (364), from the third apparatus 130, the at least one configuration regarding CHO with candidate SCG.

[0108] In addition to the above examples, in some example implementations, the at least one configuration may further include a second threshold for the second timer. With the second threshold, the first apparatus 110 may compare an elapsed value of the second timer with this second threshold, so as to transmit a successful handover report comprising information of the second timer based on the comparison.

[0109] In some example embodiments, the first apparatus 110 may start the second timer in response to detecting the interruption.

[0110] In some example embodiments, if the second timer was started after the first condition is fulfilled and is running while waiting for the second condition to be fulfilled, the first apparatus 110 may transmit the successful primary secondary cell change report comprising the information of the second timer.

[0111] Alternatively, or in addition, in some example embodiments, if an elapsed value of the second timer is larger than a second threshold, the first apparatus 110 may transmit the successful primary secondary cell change report comprising the information of the second timer.

[0112] Optionally, the first apparatus 110 may transmit a successful primary secondary cell change report to the second apparatus 120. In some example embodiments, the successful primary secondary cell change report may include an indication (for example, a flag) indicating if the second timer was started after the first condition is fulfilled and is running waiting for the second condition to be fulfilled.

[0113] As to the second apparatus 120, it may receive the successful primary secondary cell change report from the first apparatus 110. Optionally, the second apparatus 120 may forward the successful primary secondary cell change report to the third apparatus 130. Thus, the third apparatus 130 may receive the successful primary secondary cell change report from the second apparatus 120. In addition, or alternatively, the third apparatus 130 may the successful handover report from the second apparatus 120.

[0114] Referring back to FIG. 2A which corresponds to Scenario 1. In the cases discussed with reference to FIG. 2A, it is assumed that CPC condition is fulfilled first, T310 timer starts on SCG, and the CHO condition is fulfilled later.

[0115] In this scenario, the first apparatus 110 (e.g., a UE) may generate the SHR if the time between fulfillment of the two conditions is larger than a threshold. The UE may additionally include in the SHR the portion of time T310 was running on SCG while waiting for CHO condition to be fulfilled. The inclusion of this new information element may be always done (UE hard coded) or simple inclusion or based on a network configured threshold (e.g only included if elapsed time > threshold). If the SPR is also generated based on legacy 3GPP defined triggers ,i.e. elapsed T310 on SCG> Threshold,a new flag may be included, indicating if T310 started while waiting for the CHO condition to be fulfilled.

[0116] An example of how the network can use this new information for deducing the necessary corrective action is provided below. If the SPR is reported, and if the flag is present, then the SPR is discarded. Otherwise, if T310 was started earlier that CPC condition fulfilled, then the CPC execution condition may be tuned. Based on information in SHR, the CHO execution condition may be tuned to trigger CHO earlier.

[0117] In view of the above, the issue discussed with reference to the Scenario 1 can be solved. Specifically, by involving an enhancement of SPR report to include information regarding a second timer (e.g., T310 timer), the interruption time during CHO with candidate SCG successful operations can be reduced.

[0118] It is to be understood that although the above examples are discussed with the T310 timer, T310 is just an example rather than limitation. Other suitable timers, such as T312 timer, may be also applicable in example embodiments of the present disclosure.

[0119] In the following, Table 1 and Table 2 show examples of how the new information elements could be captured in the RAN2 specifications (ASN.l code) in SHR and SPR for the above two scenarios. Please note that this is just an example, actual names of IE, value ranges and so on may differ in the actual specifications.Table 1

[0120] In the following discussion with reference to FIGS. 4 to 7, the usefulness of the proposed method for scenario 1 is illustrated on a more detailed example. It is assumed that a first apparatus 110 (e.g., a UE) is connected to PCell 1 and PSCell 1, and the UE is configured with CHO with candidate SCG(s) configuration PCell 2 and PSCell 2. Further, it is assumed that the UE starts evaluating the execution conditions of candidate PCell 2 and PSCell 2 simultaneously.

[0121] FIG. 4 illustrates a schematic diagram of an example of successful execution of CHO with candidate SCG(s) according to some example embodiments of the present disclosure.

[0122] As indicated in FIG. 4, the CPC execution conditions of the candidate PSCell 2 are fulfilled first and then with some delay also the CHO execution conditions for candidate PCell 2 but during the waiting time the T310 on SCG of PSCell 1 is started. As T310 has not expired both the CHO and CPC are successfully completed as also indicated in FIG. 4.

[0123] FIG. 5 illustrates a schematic diagram of an example of possible near failure reporting after successful execution of CHO with candidate SCG(s) according to some example embodiments of the present disclosure.

[0124] As further indicated in FIG. 5, the T310 time value of the PSCell 1 above the configured threshold may lead to triggering the SPR report. However, it may have no connection to an improper setting the CPC execution conditions for PSCell 2, instead it may have a connection to wrong setting the CHO conditions for PCell 2.

[0125] The information which could help to properly identify such case is generated in the SHR due to time interval between fulfilment of the CPC and CHO executionconditions above the configured threshold as also indicated in FIG. 5. In addition, also a sub-interval with running T310 on SCG (if it started within the time interval between the fulfilment of the CPC and CHO execution conditions) is be reported within the SHR.

[0126] As shown in FIG. 5, after successful completion of the CHO with candidate SCG(s) the UE may report SHR triggered by time interval between fulfillment of the CPC and CHO conditions above the configured threshold. The SPR may also be generated by legacy trigger T310 value is above the configured threshold.

[0127] FIG. 6 illustrates a schematic diagram of an example of optimization of the CHO conditions for the CHO with candidate SCG(s) according to some example embodiments of the present disclosure.

[0128] As illustrated in FIG. 6, for this example, the operator from the SHR will evaluate that it is related to CHO with Candidate SCG(s) which was successfully completed, but there was a delay in fulfillment of the CHO conditions after CPC ones which was above the acceptable threshold which also resulted into running T310 on SCG. Operator will be able to detect it via the new information in SHR: time interval between the fulfilment of the CPC and CHO execution conditions and a sub-interval with running T310 on SCG. Using this information and the measurements related to PCelll and 2 in the SHR operator may decide to tune the mobility thresholds (CHO execution conditions) to guarantee the CHO execution conditions are met earlier.

[0129] As shown in FIG. 6, the operator from the SHR will evaluate that it is related to CHO with Candidate SCG(s) which was successfully completed, but there was a delay in fulfillment of the CHO conditions after CPC ones which was above the acceptable threshold which also resulted into running T310 on SCG which could also be trigger for SPR. Operator based on the measurements related to PCelll and 2 may decide to tune the mobility thresholds (CHO conditions) to guarantee the CHO conditions are met earlier.

[0130] FIG. 7 illustrates a schematic diagram of an example of successful execution of the CHO with candidate SCG(s) after the CHO optimization according to some example embodiments of the present disclosure.

[0131] FIG. 7 shows the conditions after successful execution of the CHO with candidate SCG(s) after the CHO optimization. As it may be seen in FIG. 7, for this example, the T310 was decreased to below the threshold to trigger the SPR. The same fortime between fulfilment of the associated conditions was decreased to below the threshold to trigger the SHR.

[0132] As indicated above the running T310 may also lead to generating the SPR. However, the SPR may not have any connection to an improper setting the CPC execution conditions. It may be desirable to correlate the two reports for operator for taking the proper optimization actions.

[0133] As shown in FIG. 7, considering the appropriate optimization is executed by operator, after successful completion of the CHO with candidate SCG(s) the UE will not report SHR as the time interval between fulfillment of the CPC and CHO conditions is below the configured threshold. The SPR will neither be generated by legacy trigger as also the T310 value is below the configured threshold.

[0134] FIG. 8 shows a flowchart of an example method 800 implemented at a first apparatus in accordance with some example embodiments of the present disclosure. For the purpose of discussion, the method 800 will be described from the perspective of the first apparatus 110 in FIG. 1.

[0135] At block 810, the first apparatus 110 determines that an elapsed time of a first timer is larger than a first threshold associated with a successful conditional handover (CHO) with candidate secondary cell group (SCG) procedure, wherein the first timer starts in response to a first condition for execution of CHO is fulfilled and stops in response to a second condition for execution of conditional primary secondary cell (PSCell) addition or change (CP AC) is fulfilled.

[0136] At block 820, the first apparatus 110 transmits, to a second apparatus, a successful primary secondary cell change report indicating an interruption of a connection to a third apparatus, wherein the successful primary secondary cell change report comprises information of a second timer associated with the connection.

[0137] In some example embodiments, the first apparatus 110 may receive, from the third apparatus, at least one configuration regarding CHO with candidate SCG comprising at least one of at least a first condition for execution of CHO, and a second condition for execution of CP AC.

[0138] In some example embodiments, wherein the at least one configuration comprises a second threshold for the second timer.

[0139] In some example embodiments, the first apparatus 110 may in response to detecting the interruption, start the second timer.

[0140] In some example embodiments, the first apparatus 110 may in response to that the second timer was started after the first condition is fulfilled and is running while waiting for the second condition to be fulfilled, and / or an elapsed value of the second timer is larger than a second threshold, transmit the successful primary secondary cell change report comprising the information of the second timer.

[0141] In some example embodiments, the information of the second timer comprises an elapsed time of the second timer or an indication indicting the second timer was started for the connection.

[0142] In some example embodiments, the first apparatus 110 may transmit, to the second apparatus, a successful handover report comprising an indication indicating if the second timer was started after the first condition is fulfilled and is running waiting for the second condition to be fulfilled.

[0143] In some example embodiments, the second timer comprises at least one of a T310 timer or a T312 timer.

[0144] In some example embodiments, the first apparatus comprises a terminal device, the second apparatus comprises a target master node, and the third apparatus comprises a source master node.

[0145] FIG. 9 shows a flowchart of an example method 900 implemented at a second apparatus in accordance with some example embodiments of the present disclosure. For the purpose of discussion, the method 900 will be described from the perspective of the second apparatus 120 in FIG. 1.

[0146] At block 910, the second apparatus 120 receives, from a first apparatus, a successful primary secondary cell change report indicating an interruption of a connection to a third apparatus, wherein the successful primary secondary cell change report comprises information of a second timer associated with the connection, and an elapsed time of a first timer is larger than a first threshold associated with a successful conditional handover (CHO) with candidate secondary cell group (SCG) procedure, and the first timer starts in response to a first condition for execution of CHO is fulfilled and stops in response to a second condition for execution of conditional primary secondary cell(PSCell) addition or change (CP AC) is fulfilled.

[0147] In some example embodiments, the information of the second timer indicates that the second timer was started after the first condition is fulfilled and is running while waiting for the second condition to be fulfilled.

[0148] In some example embodiments, the information of the second timer comprises an elapsed time of the second timer or an indication indicting the second timer was started for the connection.

[0149] In some example embodiments, the elapsed value of the second timer is larger than a second threshold.

[0150] In some example embodiments, the second apparatus 120 may receive a successful handover report from the first apparatus; and transmitting the successful handover report to the third apparatus.

[0151] In some example embodiments, the second apparatus 120 may transmit the successful primary secondary cell change report to the third apparatus.

[0152] In some example embodiments, if the successful primary secondary cell change report comprises an indication indicating the second timer was started after the second condition is fulfilled and is running waiting for the first condition to be fulfilled, the successful primary secondary cell change report is discarded.

[0153] In some example embodiments, the second timer comprises at least one of a T310 timer or a T 312 timer.

[0154] In some example embodiments, the first apparatus comprises a terminal device, the second apparatus comprises a target master node, and the third apparatus comprises a source master node

[0155] FIG. 10 shows a flowchart of an example method 1000 implemented at a third apparatus in accordance with some example embodiments of the present disclosure. For the purpose of discussion, the method 1000 will be described from the perspective of the third apparatus 130 in FIG. 1.

[0156] At block 1010, the third apparatus 130 may transmit, to a first apparatus, at least one configuration regarding conditional handover (CHO) with candidate secondary cell group (SCG) configuration that comprises at least one of at least a first condition forexecution of CHO, and a second condition for execution of conditional primary secondary cell (PSCell) addition or change (CP AC), the first apparatus is in an access procedure associated with the successful CHO with candidate SCG procedure.

[0157] In some example embodiments, the at least one configuration comprises a second threshold for a second timer, wherein the second threshold is used for comparing with an elapsed value of the second timer, so that the first apparatus transmits a successful primary secondary cell change report comprising information of the second timer based on the comparison, or wherein the at least one configuration comprises a second threshold for a second timer, wherein the second threshold is used for comparing with an elapsed value of the second timer, so that the first apparatus transmits a successful handover report comprising information of the second timer based on the comparison.

[0158] In some example embodiments, the third apparatus 130 may receive a successful primary secondary cell change report from a second apparatus; and / or receive a successful handover report from the second apparatus.

[0159] In some example embodiments, the first apparatus comprises a terminal device, the second apparatus comprises a target master node, and the third apparatus comprises a source master node.

[0160] FIG. 11 shows a flowchart of an example method 1100 implemented at a first apparatus in accordance with some example embodiments of the present disclosure. For the purpose of discussion, the method 1100 will be described from the perspective of the first apparatus 110 in FIG. 1.

[0161] At block 1110, the first apparatus 110 determines that an elapsed time of a first timer is larger than a first threshold associated with a successful conditional handover (CHO) with candidate secondary cell group (SCG) procedure, wherein the first timer starts in response to a second condition for execution of conditional primary secondary cell (PSCell) addition or change (CP AC) is fulfilled and stops in response to a first condition for execution of CHO is fulfilled.

[0162] At block 1120, the first apparatus 110 transmits, to a second apparatus, a successful handover report indicating an interruption of a connection to a source secondary node, wherein the successful handover report comprises information of a second timer associated with the connection.

[0163] In some example embodiments, the first apparatus 110 may receive, from a third apparatus, at least one configuration regarding CHO with candidate SCG configuration that comprises at least one of at least a first condition for execution of CHO, and a second condition for execution of CP AC.

[0164] In some example embodiments, the third apparatus comprises a source master node, and / or wherein the at least one configuration comprises a second threshold for the second timer.

[0165] In some example embodiments, the first apparatus 110 may in response to detecting the interruption, start the second timer.

[0166] In some example embodiments, the first apparatus 110 may in response to that the second timer was started after the second condition is fulfilled and is running while waiting for the first condition to be fulfilled, and / or an elapsed value of the second timer is larger than a second threshold, transmit the successful handover report comprising the information of the second timer.

[0167] In some example embodiments, the information of the second timer comprises an elapsed time of the second timer or an indication indicting the second timer was started for the connection.

[0168] In some example embodiments, the first apparatus 110 may transmit, to the second apparatus, a successful primary secondary cell change report comprising an indication indicating if the second timer was started after the second condition is fulfilled and is running waiting for the first condition to be fulfilled.

[0169] In some example embodiments, the second timer comprises at least one of a T310 timer or a T 312 timer.

[0170] In some example embodiments, the first apparatus comprises a terminal device, and the second apparatus comprises a target master node.

[0171] FIG. 12 shows a flowchart of an example method 1200 implemented at a second apparatus in accordance with some example embodiments of the present disclosure. For the purpose of discussion, the method 1200 will be described from the perspective of the second apparatus 120 in FIG. 1.

[0172] At block 1210, the second apparatus 120 may receive, from a first apparatus, asuccessful handover report indicating an interruption of a connection to a source secondary node, wherein the successful handover report comprises information of a second timer associated with the connection, and an elapsed time of a first timer is larger than a first threshold associated with the successful conditional handover (CHO) with candidate secondary cell group (SCG) procedure, and the first timer starts in response to a second condition for execution of conditional primary secondary cell (PSCell) addition or change (CP AC) is fulfilled and stops in response to a first condition for execution of CHO is fulfilled.

[0173] In some example embodiments, the information of the second timer indicates that the second timer was started after the second condition is fulfilled and is running while waiting for the first condition to be fulfilled.

[0174] In some example embodiments, the information of the second timer comprises an elapsed time of the second timer or an indication indicting the second timer was started for the connection.

[0175] In some example embodiments, the elapsed value of the second timer is larger than a second threshold.

[0176] In some example embodiments, the second apparatus 120 may receive a successful primary secondary cell change report from the first apparatus; and transmitting the successful primary secondary cell change report to a third apparatus.

[0177] In some example embodiments, the second apparatus 120 may transmit the successful handover report to a third apparatus.

[0178] In some example embodiments, the third apparatus comprises a source master node.

[0179] In some example embodiments, if the successful primary secondary cell change report comprises an indication indicating the second timer was started after the second condition is fulfilled and is running waiting for the first condition to be fulfilled, the successful primary secondary cell change report is discarded.

[0180] In some example embodiments, the second timer comprises at least one of a T310 timer or a T 312 timer.

[0181] In some example embodiments, the first apparatus comprises a terminal device,and the second apparatus comprises a target master node.

[0182] In some example embodiments, a first apparatus capable of performing any of the method 800 (for example, the first apparatus 110 in FIG. 1) may comprise means for performing the respective operations of the method 800. The means may be implemented in any suitable form. For example, the means may be implemented in a circuitry or software module. The first apparatus may be implemented as or included in the first apparatus 110 in FIG. 1.

[0183] In some example embodiments, the first apparatus comprises means for determining that an elapsed time of a first timer is larger than a first threshold associated with a successful conditional handover (CHO) with candidate secondary cell group (SCG) procedure, wherein the first timer starts in response to a first condition for execution of CHO is fulfilled and stops in response to a second condition for execution of conditional primary secondary cell (PSCell) addition or change (CP AC) is fulfilled; and means for transmitting, to a second apparatus, a successful primary secondary cell change report indicating an interruption of a connection to a third apparatus, wherein the successful primary secondary cell change report comprises information of a second timer associated with the connection.

[0184] In some example embodiments, the first apparatus further comprises: means for receiving, from the third apparatus, at least one configuration regarding CHO with candidate SCG comprising at least one of at least a first condition for execution of CHO, and a second condition for execution of CP AC.

[0185] In some example embodiments, the at least one configuration comprises a second threshold for the second timer.

[0186] In some example embodiments, the first apparatus further comprises: means for in response to detecting the interruption, starting the second timer.

[0187] In some example embodiments, the first apparatus further comprises: means for in response to that the second timer was started after the first condition is fulfilled and is running while waiting for the second condition to be fulfilled, and / or an elapsed value of the second timer is larger than a second threshold, transmitting the successful primary secondary cell change report comprising the information of the second timer.

[0188] In some example embodiments, the information of the second timer comprisesan elapsed time of the second timer or an indication indicting the second timer was started for the connection.

[0189] In some example embodiments, the first apparatus further comprises: means for transmitting, to the second apparatus, a successful handover report comprising an indication indicating if the second timer was started after the first condition is fulfilled and is running waiting for the second condition to be fulfilled.

[0190] In some example embodiments, the second timer comprises at least one of a T310 timer or a T312 timer.

[0191] In some example embodiments, the first apparatus comprises a terminal device, the second apparatus comprises a target master node, and the third apparatus comprises a source master node.

[0192] In some example embodiments, the first apparatus further comprises means for performing other operations in some example embodiments of the method 800 or the first apparatus 110. In some example embodiments, the means comprises at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the performance of the first apparatus.

[0193] In some example embodiments, a second apparatus capable of performing any of the method 900 (for example, the second apparatus 120 in FIG. 1) may comprise means for performing the respective operations of the method 900. The means may be implemented in any suitable form. For example, the means may be implemented in a circuitry or software module. The second apparatus may be implemented as or included in the second apparatus 120 in FIG. 1.

[0194] In some example embodiments, the second apparatus comprises means for receiving, from a first apparatus, a successful primary secondary cell change report indicating an interruption of a connection to a third apparatus, wherein the successful primary secondary cell change report comprises information of a second timer associated with the connection, and wherein an elapsed time of a first timer is larger than a first threshold associated with a successful conditional handover (CHO) with candidate secondary cell group (SCG) procedure, and the first timer starts in response to a first condition for execution of CHO is fulfilled and stops in response to a second condition for execution of conditional primary secondary cell (PSCell) addition or change (CP AC)is fulfilled.

[0195] In some example embodiments, the information of the second timer indicates that the second timer was started after the first condition is fulfilled and is running while waiting for the second condition to be fulfilled.

[0196] In some example embodiments, the information of the second timer comprises an elapsed time of the second timer or an indication indicting the second timer was started for the connection.

[0197] In some example embodiments, the elapsed value of the second timer is larger than a second threshold.

[0198] In some example embodiments, the second apparatus further comprises: means for receiving a successful handover report from the first apparatus; and means for transmitting the successful handover report to the third apparatus.

[0199] In some example embodiments, the second apparatus further comprises: means for transmitting the successful primary secondary cell change report to the third apparatus.

[0200] In some example embodiments, if the successful primary secondary cell change report comprises an indication indicating the second timer was started after the second condition is fulfilled and is running waiting for the first condition to be fulfilled, the successful primary secondary cell change report is discarded.

[0201] In some example embodiments, the second timer comprises at least one of: a T310 timer or a T 312 timer.

[0202] In some example embodiments, the first apparatus comprises a terminal device, the second apparatus comprises a target master node, and the third apparatus comprises a source master node

[0203] In some example embodiments, the second apparatus further comprises means for performing other operations in some example embodiments of the method 900 or the second apparatus 120. In some example embodiments, the means comprises at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the performance of the second apparatus.

[0204] In some example embodiments, a third apparatus capable of performing any of the method 1000 (for example, the third apparatus 130 in FIG. 1) may comprise meansfor performing the respective operations of the method 1000. The means may be implemented in any suitable form. For example, the means may be implemented in a circuitry or software module. The third apparatus may be implemented as or included in the third apparatus 130 in FIG. 1.

[0205] In some example embodiments, the third apparatus comprises means for transmitting, to a first apparatus, at least one configuration regarding conditional handover (CHO) with candidate secondary cell group (SCG) configuration that comprises at least one of at least a first condition for execution of CHO, and a second condition for execution of conditional primary secondary cell (PSCell) addition or change (CP AC), wherein the first apparatus is in an access procedure associated with the successful CHO with candidate SCG procedure.

[0206] In some example embodiments, the at least one configuration comprises a second threshold for a second timer, wherein the second threshold is used for comparing with an elapsed value of the second timer, so that the first apparatus transmits a successful primary secondary cell change report comprising information of the second timer based on the comparison, or wherein the at least one configuration comprises a second threshold for a second timer, wherein the second threshold is used for comparing with an elapsed value of the second timer, so that the first apparatus transmits a successful handover report comprising information of the second timer based on the comparison.

[0207] In some example embodiments, the third apparatus further comprises: means for receiving a successful primary secondary cell change report from a second apparatus; and / or means for receiving a successful handover report from the second apparatus.

[0208] In some example embodiments, the first apparatus comprises a terminal device, the second apparatus comprises a target master node, and the third apparatus comprises a source master node.

[0209] In some example embodiments, the third apparatus further comprises means for performing other operations in some example embodiments of the method 1000 or the third apparatus 130. In some example embodiments, the means comprises at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the performance of the third apparatus.

[0210] In some example embodiments, a first apparatus capable of performing any ofthe method 1100 (for example, the first apparatus 110 in FIG. 1) may comprise means for performing the respective operations of the method 1100. The means may be implemented in any suitable form. For example, the means may be implemented in a circuitry or software module. The first apparatus may be implemented as or included in the first apparatus 110 in FIG. 1

[0211] In some example embodiments, the first apparatus comprises means for determining that an elapsed time of a first timer is larger than a first threshold associated with a successful conditional handover (CHO) with candidate secondary cell group (SCG) procedure, wherein the first timer starts in response to a second condition for execution of conditional primary secondary cell (PSCell) addition or change (CP AC) is fulfilled and stops in response to a first condition for execution of CHO is fulfilled; and means for transmitting, to a second apparatus, a successful handover report indicating an interruption of a connection to a source secondary node, wherein the successful handover report comprises information of a second timer associated with the connection.

[0212] In some example embodiments, the first apparatus further comprises: means for receiving, from a third apparatus, at least one configuration regarding CHO with candidate SCG configuration that comprises at least one of at least a first condition for execution of CHO, and a second condition for execution of CP AC.

[0213] In some example embodiments, the third apparatus comprises a source master node, and / or wherein the at least one configuration comprises a second threshold for the second timer.

[0214] In some example embodiments, the first apparatus further comprises: means for in response to detecting the interruption, starting the second timer.

[0215] In some example embodiments, the first apparatus further comprises: means for in response to that the second timer was started after the second condition is fulfilled and is running while waiting for the first condition to be fulfilled, and / or an elapsed value of the second timer is larger than a second threshold, transmitting the successful handover report comprising the information of the second timer.

[0216] In some example embodiments, the information of the second timer comprises an elapsed time of the second timer or an indication indicting the second timer was started for the connection.

[0217] In some example embodiments, the first apparatus further comprises: means for transmitting, to the second apparatus, a successful primary secondary cell change report comprising an indication indicating if the second timer was started after the second condition is fulfilled and is running waiting for the first condition to be fulfilled.

[0218] In some example embodiments, the second timer comprises at least one of a T310 timer or a T 312 timer.

[0219] In some example embodiments, the first apparatus comprises a terminal device, and the second apparatus comprises a target master node.

[0220] In some example embodiments, the first apparatus further comprises means for performing other operations in some example embodiments of the method 1100 or the first apparatus 110. In some example embodiments, the means comprises at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the performance of the first apparatus.

[0221] In some example embodiments, a second apparatus capable of performing any of the method 1200 (for example, the second apparatus 120 in FIG. 1) may comprise means for performing the respective operations of the method 1200. The means may be implemented in any suitable form. For example, the means may be implemented in a circuitry or software module. The second apparatus may be implemented as or included in the second apparatus 120 in FIG. 1.

[0222] In some example embodiments, the second apparatus comprises means for receiving, from a first apparatus, a successful handover report indicating an interruption of a connection to a source secondary node, wherein the successful handover report comprises information of a second timer associated with the connection, and wherein an elapsed time of a first timer is larger than a first threshold associated with the successful conditional handover (CHO) with candidate secondary cell group (SCG) procedure, and the first timer starts in response to a second condition for execution of conditional primary secondary cell (PSCell) addition or change (CP AC) is fulfilled and stops in response to a first condition for execution of CHO is fulfilled.

[0223] In some example embodiments, the information of the second timer indicates that the second timer was started after the second condition is fulfilled and is running while waiting for the first condition to be fulfilled.

[0224] In some example embodiments, the information of the second timer comprises an elapsed time of the second timer or an indication indicting the second timer was started for the connection.

[0225] In some example embodiments, the elapsed value of the second timer is larger than a second threshold.

[0226] In some example embodiments, the second apparatus further comprises: means for receiving a successful primary secondary cell change report from the first apparatus; and means for transmitting the successful primary secondary cell change report to a third apparatus.

[0227] In some example embodiments, the second apparatus further comprises: means for transmitting the successful handover report to a third apparatus.

[0228] In some example embodiments, the third apparatus comprises a source master node.

[0229] In some example embodiments, if the successful primary secondary cell change report comprises an indication indicating the second timer was started after the second condition is fulfilled and is running waiting for the first condition to be fulfilled, the successful primary secondary cell change report is discarded.

[0230] In some example embodiments, the second timer comprises at least one of: a T310 timer or a T312 timer.

[0231] In some example embodiments, the first apparatus comprises a terminal device, and the second apparatus comprises a target master node.

[0232] In some example embodiments, the second apparatus further comprises means for performing other operations in some example embodiments of the method 1200 or the second apparatus 120. In some example embodiments, the means comprises at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the performance of the second apparatus.

[0233] FIG. 13 is a simplified block diagram of a device 1300 that is suitable for implementing example embodiments of the present disclosure. The device 1300 may be provided to implement a communication device, for example, the first apparatus 110 or the second apparatus 120 or the third apparatus 130. As shown, the device 1300 includesone or more processors 1310, one or more memories 1320 coupled to the processor 1310, and one or more communication modules 1340 coupled to the processor 1310.

[0234] The communication module 1340 is for bidirectional communications. The communication module 1340 has one or more communication interfaces to facilitate communication with one or more other modules or devices. The communication interfaces may represent any interface that is necessary for communication with other network elements. In some example embodiments, the communication module 1340 may include at least one antenna.

[0235] The processor 1310 may be of any type suitable to the local technical network and may include one or more of the following: general purpose computers, special purpose computers, microprocessors, digital signal processors (DSPs) and processors based on multicore processor architecture, as non-limiting examples. The device 1300 may have multiple processors, such as an application specific integrated circuit chip that is slaved in time to a clock which synchronizes the main processor.

[0236] The memory 1320 may include one or more non-volatile memories and one or more volatile memories. Examples of the non-volatile memories include, but are not limited to, a Read Only Memory (ROM) 1324, an electrically programmable read only memory (EPROM), a flash memory, a hard disk, a compact disc (CD), a digital video disk (DVD), an optical disk, a laser disk, and other magnetic storage and / or optical storage. Examples of the volatile memories include, but are not limited to, a random access memory (RAM) 1322 and other volatile memories that will not last in the powerdown duration.

[0237] A computer program 1330 includes computer executable instructions that are executed by the associated processor 1310. The instructions of the program 1330 may include instructions for performing operations / acts of some example embodiments of the present disclosure. The program 1330 may be stored in the memory, e.g., the ROM 1324. The processor 1310 may perform any suitable actions and processing by loading the program 1330 into the RAM 1322.

[0238] The example embodiments of the present disclosure may be implemented by means of the program 1330 so that the device 1300 may perform any process of the disclosure as discussed with reference to FIG. 3A to FIG. 12. The example embodiments of the present disclosure may also be implemented by hardware or by a combination ofsoftware and hardware.

[0239] In some example embodiments, the program 1330 may be tangibly contained in a computer readable medium which may be included in the device 1300 (such as in the memory 1320) or other storage devices that are accessible by the device 1300. The device 1300 may load the program 1330 from the computer readable medium to the RAM 1322 for execution. In some example embodiments, the computer readable medium may include any types of non -transitory storage medium, such as ROM, EPROM, a flash memory, a hard disk, CD, DVD, 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).

[0240] FIG. 14 shows an example of the computer readable medium 1400 which may be in form of CD, DVD or other optical storage disk. The computer readable medium 1400 has the program 1330 stored thereon.

[0241] Generally, various embodiments of the present disclosure may be implemented in hardware or special purpose circuits, software, logic or any combination thereof. Some aspects may be implemented in hardware, and other aspects may be implemented in firmware or software which may be executed by a controller, microprocessor or other computing device. Although various aspects of embodiments of the present disclosure are illustrated and described as block diagrams, flowcharts, or using some other pictorial representations, it is to be understood that the block, apparatus, system, technique or method described herein may be implemented in, as non-limiting examples, hardware, software, firmware, special purpose circuits or logic, general purpose hardware or controller or other computing devices, or some combination thereof.

[0242] Some example embodiments of the present disclosure also provide at least one computer program product tangibly stored on a computer readable medium, such as a non-transitory computer readable medium. The computer program product includes computer-executable instructions, such as those included in program modules, being executed in a device on a target physical or virtual processor, to carry out any of the methods as described above. Generally, program modules include routines, programs, libraries, objects, classes, components, data structures, or the like that perform particular tasks or implement particular abstract data types. The functionality of the program modules may be combined or split between program modules as desired in variousembodiments. Machine-executable instructions for program modules may be executed within a local or distributed device. In a distributed device, program modules may be located in both local and remote storage media.

[0243] Program code for carrying out methods of the present disclosure may be written in any combination of one or more programming languages. The program code may be provided to a processor or controller of a general purpose computer, special purpose computer, or other programmable data processing apparatus, such that the program code, when executed by the processor or controller, cause the functions / operations specified in the flowcharts and / or block diagrams to be implemented. The program code 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.

[0244] In the context of the present disclosure, the computer program code or related data may be carried by any suitable carrier to enable the device, apparatus or processor to perform various processes and operations as described above. Examples of the carrier include a signal, computer readable medium, and the like.

[0245] The computer readable medium may be a computer readable signal medium or a computer readable storage medium. A computer readable medium may include but 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 computer 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 readonly memory (EPROM or Flash memory), an optical fiber, a portable compact disc readonly memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.

[0246] Further, although 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, although several specific implementation details are contained in the above discussions, these should not be construed as limitations on the scope of thepresent disclosure, but rather as descriptions of features that may be specific to particular embodiments. Unless explicitly stated, certain features that are described in the context of separate embodiments may also be implemented in combination in a single embodiment. Conversely, unless explicitly stated, various features that are described in the context of a single embodiment may also be implemented in a plurality of embodiments separately or in any suitable sub-combination.

[0247] Although the present disclosure has been described in languages specific to structural features and / or methodological acts, it is to be understood that the present disclosure defined in the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as example forms of implementing the claims.

Claims

WHAT IS CLAIMED IS:

1. A first apparatus comprising: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the first apparatus at least to: determine that an elapsed time of a first timer is larger than a first threshold associated with a successful conditional handover (CHO) with candidate secondary cell group (SCG) procedure, wherein the first timer starts in response to a second condition for execution of conditional primary secondary cell (PSCell) addition or change (CP AC) is fulfilled and stops in response to a first condition for execution of CHO is fulfilled; and transmit, to a second apparatus, a successful handover report indicating an interruption of a connection to a source secondary node, wherein the successful handover report comprises information of a second timer associated with the connection.

2. The first apparatus of claim 1, wherein the first apparatus is caused to: receive, from a third apparatus, at least one configuration regarding CHO with candidate SCG configuration that comprises at least one of: at least a first condition for execution of CHO, and a second condition for execution of CP AC.

3. The first apparatus of claim 2, wherein the third apparatus comprises a source master node, and / or wherein the at least one configuration comprises a second threshold for the second timer.

4. The first apparatus of any of claims 1 to 3, wherein the first apparatus is caused to: in response to detecting the interruption, start the second timer.

5. The first apparatus of any of claims 1 to 4, wherein the first apparatus is caused to: in response to that the second timer was started after the second condition is fulfilled and is running while waiting for the first condition to be fulfilled, and / or an elapsed value of the second timer is larger than a second threshold, transmit the successful handover report comprising the information of the second timer.

466. The first apparatus of any of claims 1 to 5, wherein the information of the second timer comprises an elapsed time of the second timer or an indication indicting the second timer was started for the connection.

7. The first apparatus of any of claims 1 to 6, wherein the first apparatus is caused to: transmit, to the second apparatus, a successful primary secondary cell change report comprising an indication indicating if the second timer was started after the second condition is fulfilled and is running waiting for the first condition to be fulfilled.

8. The first apparatus of any of claims 1 to 7, wherein the second timer comprises at least one of a T310 timer or a T 312 timer.

9. The first apparatus of any of claims 1 to 8, wherein the first apparatus comprises a terminal device, and the second apparatus comprises a target master node.

10. A second apparatus comprising: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the second apparatus at least to: receive, from a first apparatus, a successful handover report indicating an interruption of a connection to a source secondary node, wherein the successful handover report comprises information of a second timer associated with the connection, and wherein an elapsed time of a first timer is larger than a first threshold associated with the successful conditional handover (CHO) with candidate secondary cell group (SCG) procedure, and the first timer starts in response to a second condition for execution of conditional primary secondary cell (PSCell) addition or change (CP AC) is fulfilled and stops in response to a first condition for execution of CHO is fulfilled.

11. The second apparatus of claim 10, wherein the information of the second timer indicates that the second timer was started after the second condition is fulfilled and is running while waiting for the first condition to be fulfilled.4712. The second apparatus of claim 10 or 11, wherein the information of the second timer comprises an elapsed time of the second timer or an indication indicting the second timer was started for the connection.

13. The second apparatus of claim 12, wherein the elapsed value of the second timer is larger than a second threshold.

14. The second apparatus of any of claims 10 to 13, wherein the second apparatus is caused to: receive a successful primary secondary cell change report from the first apparatus; and transmit the successful primary secondary cell change report to a third apparatus.

15. The second apparatus of any of claims 10 to 14, wherein the second apparatus is caused to: transmit the successful handover report to a third apparatus.

16. The second apparatus of claim 14 or 15, wherein the third apparatus comprises a source master node.

17. The second apparatus of any of claims 14 to 16, wherein if the successful primary secondary cell change report comprises an indication indicating the second timer was started after the second condition is fulfilled and is running waiting for the first condition to be fulfilled, the successful primary secondary cell change report is discarded.

18. The second apparatus of any of claims 10 to 17, wherein the second timer comprises at least one of: a T310 timer or a T 312 timer.

19. The second apparatus of any of claims 10 to 18, wherein the first apparatus comprises a terminal device, and the second apparatus comprises a target master node.

20. A third apparatus comprising: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the third apparatus at least to:48transmit, to a first apparatus, at least one configuration regarding conditional handover (CHO) with candidate secondary cell group (SCG) configuration that comprises at least one of at least a first condition for execution of CHO, and a second condition for execution of conditional primary secondary cell (PSCell) addition or change (CP AC), wherein the first apparatus is in an access procedure associated with the successful CHO with candidate SCG procedure.

21. The third apparatus of claim 20, wherein the at least one configuration comprises a second threshold for a second timer, wherein the second threshold is used for comparing with an elapsed value of the second timer, so that the first apparatus transmits a successful handover report comprising information of the second timer based on the comparison.

22. The third apparatus of claim 20, wherein the third apparatus is caused to: receive a successful handover report from a second apparatus; and / or receive a successful primary secondary cell change report from the second apparatus.

23. The third apparatus of claim 22, wherein the first apparatus comprises a terminal device, the second apparatus comprises a target master node, and the third apparatus comprises a source master node.

24. A method comprising: determining that an elapsed time of a first timer is larger than a first threshold associated with a successful conditional handover (CHO) with candidate secondary cell group (SCG) procedure, wherein the first timer starts in response to a second condition for execution of conditional primary secondary cell (PSCell) addition or change (CP AC) is fulfilled and stops in response to a first condition for execution of CHO is fulfilled; and transmitting, to a second apparatus, a successful handover report indicating an interruption of a connection to a source secondary node, wherein the successful handover report comprises information of a second timer associated with the connection.

25. A method comprising: receiving, from a first apparatus, a successful handover report indicating an interruption of a connection to a source secondary node, wherein the successful handover report comprisesinformation of a second timer associated with the connection, and wherein an elapsed time of a first timer is larger than a first threshold associated with the successful conditional handover (CHO) with candidate secondary cell group (SCG) procedure, and the first timer starts in response to a second condition for execution of conditional primary secondary cell (PSCell) addition or change (CP AC) is fulfilled and stops in response to a first condition for execution of CHO is fulfilled.

26. A method comprising: transmitting, to a first apparatus, at least one configuration regarding conditional handover (CHO) with candidate secondary cell group (SCG) configuration that comprises at least one of: at least a first condition for execution of CHO, and a second condition for execution of conditional primary secondary cell (PSCell) addition or change (CP AC), wherein the first apparatus is in an access procedure associated with the successful CHO with candidate SCG procedure.

27. A first apparatus comprising: means for determining that an elapsed time of a first timer is larger than a first threshold associated with a successful conditional handover (CHO) with candidate secondary cell group (SCG) procedure, wherein the first timer starts in response to a second condition for execution of conditional primary secondary cell (PSCell) addition or change (CP AC) is fulfilled and stops in response to a first condition for execution of CHO is fulfilled; and means for transmitting, to a second apparatus, a successful handover report indicating an interruption of a connection to a source secondary node, wherein the successful handover report comprises information of a second timer associated with the connection.

28. A second apparatus comprising: means for receiving, from a first apparatus, a successful handover report indicating an interruption of a connection to a source secondary node, wherein the successful handover report comprises information of a second timer associated with the connection, and wherein an elapsed time of a first timer is larger than a first threshold associated with the successful conditional handover (CHO) with candidate secondary cell group (SCG) procedure, and the first timer starts in response to a second condition for execution ofconditional primary secondary cell (PSCell) addition or change (CP AC) is fulfilled and stops in response to a first condition for execution of CHO is fulfilled.

29. A third apparatus comprising: means for transmitting, to a first apparatus, at least one configuration regarding conditional handover (CHO) with candidate secondary cell group (SCG) configuration that comprises at least one of: at least a first condition for execution of CHO, and a second condition for execution of conditional primary secondary cell (PSCell) addition or change (CP AC), wherein the first apparatus is in an access procedure associated with the successful CHO with candidate SCG procedure.

30. A computer readable medium comprising instructions stored thereon for causing an apparatus at least to perform the method of any of claims 24 to 26.

Images