Multiple conditional configurations for the same handover request

Abstract

Described herein is a first network node in a radio access network that controls a source cell for a user equipment (UE), the first network node being a master node for carrier aggregation or dual connectivity for the UE in the radio access network, the first network node comprising at least one processor and at least one memory storing instructions that, when executed by the at least one processor, cause the first network node to perform the following steps: determine a conditional handover for the UE served by the source cell; send a conditional handover request for the UE to a second network node that controls a potential target cell for the UE in the radio access network, the second network node being a target master node for carrier aggregation or dual connectivity for the UE; receive a conditional handover request acknowledgement from the second network node, the conditional handover request acknowledgement including at least one conditional configuration for a target cell for the handover; and maintain a count of conditional configurations for the UE.

Description

[Technical Field]

[0001] The present disclosure relates to conditional handovers, and in particular to multiple conditional configurations for the same handover request. [Background technology]

[0002] Any discussion of background art throughout this specification should not be taken as an admission that such art is widely known or forms part of the common general knowledge in the field.

[0003] Release 16 introduces conditional handover (CHO). A user equipment (UE) is configured with a CHO target cell configuration and at least one CHO execution condition to determine when to perform a handover to one or more prepared target cells. The UE evaluates the CHO conditions and when one condition is met for a particular target cell, the UE applies the target cell's CHO configuration and switches to this target cell. Currently, the UE is limited to considering a maximum of eight conditional configurations in CHO.

[0004] During the CHO procedure, the target Radio Access Network (RAN) node sends multiple conditional configurations of primary cells of a secondary cell group (PSCell) as a response to a single CHO request to the source RAN node, unaware of the number of already existing conditional configurations on the UE side. Meanwhile, the source node does not know which of the prepared PSCells has good radio conditions and is important. Therefore, the source node cannot select the best PSCell and the corresponding conditional configuration to present to the UE. Summary of the Invention [Problem to be solved by the invention]

[0005] Therefore, there is a need to limit and control the number of conditional configurations of CHO that are provided to a UE. [Means for solving the problem]

[0006] According to one aspect of the present disclosure, there is provided a first network node configured to support establishment of a connection for a user equipment (UE) via a radio access network, the first network node comprising: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the first network node to perform at least the following steps: determining to prepare a conditional handover for the UE towards a second network node based on measurements performed by the UE; sending a conditional handover request for the UE towards the second network node, the conditional handover request including an indication related to a number of conditional configurations for which the second network node is authorized to prepare the handover; and receiving a conditional handover request acknowledgement from the second network node, the conditional handover request including at least one conditional configuration related to at least one target cell for the handover.

[0007] In some embodiments, the network node is configured to maintain a number of conditional configurations allocated to the UE and to update this number after receiving a conditional handover request acknowledgement.

[0008] In some embodiments, the network node is configured to determine the maximum number of conditional configurations that can be allocated to and / or supported by the UE.

[0009] In some embodiments, the network node is configured to send a conditional handover request for the UE towards a third network node, the conditional handover request including an indication related to the number of conditional configurations for which the third network node is permitted to prepare for the handover, this number being coordinated with the number sent to the second node and the maximum number supported by the user equipment.

[0010] In some embodiments, the network node is configured to transmit a message towards the UE including an indication related to the received at least one conditional configuration related to at least one target cell of the second network node.

[0011] In some embodiments, the conditional handover request acknowledgement includes at least one conditional configuration of a number included in the conditional handover request acknowledgement.

[0012] According to one aspect of the present disclosure, there is provided a first network node configured to support establishment of a connection towards a user equipment (UE) via a wireless access link, the first network node comprising: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the first network node to perform at least the following steps: determining to prepare a conditional handover for the UE towards a second network node based on measurements performed by the UE; sending a conditional handover request for the UE towards the second network node; and receiving a conditional handover request acknowledgement from the second network node, the conditional handover request acknowledgement including an indication that at least one additional conditional configuration associated with one or more further target cells is available for handover.

[0013] In some embodiments, the first network node is configured to determine whether the UE can be allocated at least one or more conditional configurations, and in that case, to send a further conditional handover request to the second network node to obtain another conditional configuration associated with a further target cell.

[0014] In some embodiments, the further conditional handover request includes an indication that the second network node will not release the existing provisioning to the target cell and will return another conditional configuration relating to the further target cell (PSCell-2) in another conditional handover request acknowledgement.

[0015] In some embodiments, the conditional handover request acknowledgment includes a conditional configuration for a primary cell of the primary cell group and a primary cell of the secondary cell group, and another conditional handover request acknowledgment includes a conditional configuration for another primary cell of the secondary cell group.

[0016] In some embodiments, a conditional handover request acknowledgment includes a conditional configuration for a primary cell in a primary cell group and a primary cell in a secondary cell group, and another conditional handover request acknowledgment includes a conditional configuration for another primary cell in a secondary cell group and the same primary cell in the primary cell group.

[0017] In some embodiments, the first network node is configured to compile various conditional handover request acknowledgements for the same UE with the received conditional configuration and to transmit a message towards the UE including an indication related to the compiled at least one conditional configuration associated with at least one target cell of the second network node.

[0018] In some embodiments, the conditional handover request acknowledgement includes a unique identifier associated with the conditional configuration included in the conditional handover request acknowledgement.

[0019] In some embodiments, the conditional handover request comprises a request to prepare a conditional handover towards the second network node and the secondary node, and the first network node is further configured to receive a conditional handover request acknowledgement from the second network node comprising at least one conditional configuration relating to at least one target cell of the second network node and at least one secondary cell of the secondary node.

[0020] In some embodiments, the first network node is a source master node for dual connectivity of the UE in a radio access network, the second network node is a target master node for dual connectivity of the UE, the conditional handover request includes an indication of a primary cell (PCell) associated with the second network node, and the conditional handover request acknowledgment includes one or more indications of secondary cells (PSCells) associated with the secondary node.

[0021] In some embodiments, the first network node is configured to receive from the UE an indication of the number of conditional configurations for conditional handover that the UE can support.

[0022] According to one aspect of the present disclosure, there is provided a second network node configured to support establishment of a connection towards a user equipment (UE) via a radio access network, the second network node comprising: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the second network node to at least: receive a conditional handover request for the UE from a first network node, the conditional handover request including an indication related to a number of conditional configurations for which the second network node is authorized to prepare for the handover; determine, based on the received conditional handover request, that a plurality of target cells controlled by the second network node are to be prepared for the handover; and send a conditional handover request acknowledgement towards the first network node, the conditional handover request including at least one conditional configuration related to at least one target cell of the handover.

[0023] In some embodiments, the received conditional handover request comprises information regarding radio measurements made by the UE towards the target cell, and the second network node is configured to determine target cells and the respective number of conditional configurations that are potentially available for the conditional handover request based on the radio measurements and the number of conditional configurations for which the second network node is permitted to prepare the handover.

[0024] In some embodiments, the second network node is configured to send a request to the secondary node to prepare multiple target cells for handover, and to receive an acknowledgement from the secondary node including conditional configurations for the prepared target cells.

[0025] In some embodiments, the second network node is a target master node for dual connectivity of the UE in the radio access network, the request to prepare multiple target cells is a request to add a secondary node (SN), the conditional handover request includes an indication of a primary cell (PCell) associated with the second network node, and the conditional handover request acknowledgment includes one or more indications of secondary cells (PSCells) associated with the secondary node.

[0026] According to one aspect of the present disclosure, there is provided a second network node configured to support establishment of a connection towards a user equipment (UE) via a radio access network, the second network node comprising: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the second network node to at least: receive a conditional handover request for the UE from a first network node, the conditional handover request including information about radio measurements made by the UE towards the target cell; determine that a plurality of target cells controlled by the second network node are to be prepared for handover; and send a conditional handover request acknowledgement towards the first network node including an indication that at least one additional conditional configuration of one or more further target cells is available for handover.

[0027] In some embodiments, determining that a plurality of target cells associated with the second network node are potentially available for handover is based on information relating to radio measurements of the target cells.

[0028] In some embodiments, the second network node is configured to: send a request to the secondary node to prepare a target cell for handover, the request to prepare the target cell including at least part of the received information regarding radio measurements for the target cell; and receive an acknowledgement from the secondary node including a conditional configuration for the prepared target cell, the acknowledgement including an indication that multiple target cells controlled by the secondary node are potentially available for handover.

[0029] In some embodiments, the second network node is configured to receive from the first network node a further conditional handover request including an indication that the second network node does not release existing preparations for the target cell and returns another conditional configuration for the further target cell in the further conditional handover request acknowledgement.

[0030] In some embodiments, the second network node is configured to decide to add a further target cell for the handover by sending another request to the secondary node to prepare the further target cell for the handover and receiving another acknowledgement from the secondary node including the conditional configuration for the prepared further target cell, and to send another conditional handover request acknowledgement to the first network node including the conditional configuration for the further target cell.

[0031] In some embodiments, the conditional handover request acknowledgement includes a unique identifier associated with the conditional configuration included in the conditional handover request acknowledgement.

[0032] In some embodiments, the second network node is a target master node for dual connectivity of the UE in the radio access network, the request to prepare the target cell is a request to add a secondary node (SN), the conditional handover request includes an indication of a primary cell (PCell) associated with the second network node, and the conditional handover request acknowledgment includes one or more indications of secondary cells (PSCells) associated with the secondary node.

[0033] According to one aspect of the present disclosure, there is provided a user equipment (UE) configured to operate in a radio access network, the UE comprising: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the UE to perform at least the steps of: indicating to a network a number of conditional configurations for conditional handover that the UE can support; transmitting to a network node measurements of target cells for a potential handover; and receiving from the network node a message for conditional handover that includes an indication related to at least one conditional configuration associated with at least one of the target cells.

[0034] In some embodiments, the user equipment is configured to evaluate at least one conditional configuration and, if at least one condition is valid, perform a handover towards a target cell associated with the satisfied condition.

[0035] According to one aspect of the present disclosure, there is provided a system including a first network node as described above and a user equipment (UE) as described above served by a cell of the first network node.

[0036] According to one aspect of the present disclosure, there is provided a method for a first network node configured to support establishment of a connection towards a user equipment (UE) via a radio access network, the method comprising: determining preparation of a conditional handover for the UE towards a second network node based on measurements performed by the UE; sending a conditional handover request for the UE towards the second network node, the conditional handover request including an indication related to a number of conditional configurations for which the second network node is authorized to prepare the handover; and receiving a conditional handover request acknowledgement from the second network node, the conditional handover request including at least one conditional configuration related to at least one target cell for the handover.

[0037] According to one aspect of the present disclosure, there is provided a method in a first network node configured to support establishment of a connection for a user equipment (UE) via a radio access network, the method comprising: determining to prepare a conditional handover for the UE towards a second network node based on measurements performed by the UE; sending a conditional handover request for the UE towards the second network node; and receiving a conditional handover request acknowledgement from the second network node including an indication that at least one additional conditional configuration associated with one or more further target cells is available for handover.

[0038] According to one aspect of the present disclosure, there is provided a method for a second network node configured to support establishment of a connection towards a user equipment (UE) via a radio access network, the method comprising: receiving a conditional handover request for the UE from a first network node, the conditional handover request including an indication related to a number of conditional configurations for which the second network node is authorized to prepare for the handover; determining, based on the received conditional handover request, that a plurality of target cells controlled by the second network node are to be prepared for the handover; and transmitting a conditional handover request acknowledgement towards the first network node, the conditional handover request acknowledgement including at least one conditional configuration related to at least one target cell for the handover.

[0039] According to one aspect of the present disclosure, there is provided a method for a second network node configured to support establishment of a connection towards a user equipment (UE) via a radio access network, the method comprising: receiving a conditional handover request for the UE from a first network node, the conditional handover request including information on radio measurements of the target cell made by the UE; determining that a plurality of target cells controlled by the second network node are to be prepared for handover; and transmitting a conditional handover request acknowledgement towards the first network node including an indication that at least one additional conditional configuration of one or more further target cells is available for handover.

[0040] According to one aspect of the present disclosure, there is provided a method for a user equipment (UE) configured to operate in a radio access network, the method including the steps of indicating to a network a number of conditional configurations for conditional handover that the UE can support, transmitting measurements of target cells for the potential handover to a network node, and receiving from the network node a message for the conditional handover including an indication related to at least one conditional configuration associated with at least one of the target cells.

[0041] According to one aspect of the present disclosure, there is provided a computer program product including instructions for causing an apparatus to perform any of the above methods, and a memory storing computer-readable instructions for causing an apparatus to perform any of the above methods.

[0042] Additionally, according to some other exemplary embodiments, there is provided a computer program product for, for example, a wireless communication device including at least one processor, the computer program product including software code portions that perform the respective steps disclosed in the present disclosure when the product is executed on the device. The computer program product may include a computer-readable medium on which the software code portions are stored. Furthermore, the computer program product may be directly loadable into the internal memory of a computer and / or transmittable over a network by means of at least one of an upload, download, and push procedure.

[0043] Although certain exemplary embodiments are described herein with particular reference to the above-mentioned applications, it will be understood that the present disclosure is not limited to such fields of use, but may be used in a broader context.

[0044] It should be noted that the methods according to the present disclosure relate to methods of operating the apparatus according to the above exemplary embodiments and variations thereof, and it is understood that each description made with respect to the apparatus also applies to the corresponding method, and vice versa, and similar descriptions may be omitted for brevity. In addition, the above aspects can be combined in many ways, even if not explicitly disclosed. Those skilled in the art will understand that these combinations of aspects and features / steps are possible unless they result in a contradiction that is expressly excluded.

[0045] Implementations of the disclosed devices may include, but are not limited to, the use of one or more processors, one or more application specific integrated circuits (ASICs), and / or one or more field programmable gate arrays (FPGAs). Device implementations may also include the use of other conventional and / or customized hardware, such as software programmable processors, such as graphics processing unit (GPU) processors.

[0046] Other and further exemplary embodiments of the present disclosure will become apparent during the course of the following description and by reference to the accompanying drawings.

[0047] Exemplary embodiments of the present disclosure will now be described, by way of example only, with reference to the accompanying drawings, in which: [Brief explanation of the drawings]

[0048] [Figure 1] FIG. 1 is a schematic diagram illustrating an example of a signaling / messaging flow diagram for conditional handover. [Figure 2] FIG. 1 is a schematic diagram illustrating an example of a signaling / messaging flow diagram for conditional handover, according to an exemplary embodiment of the present disclosure. [Figure 3] FIG. 10 is a schematic diagram illustrating another example of a signaling / messaging flow diagram for conditional handover, according to an exemplary embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0049] Hereinafter, different illustrative embodiments will be described using a communication network architecture based on 3GPP standards for communication networks such as 5G / NR as an example of a communication network to which the example embodiments can be applied, but the embodiments are not limited to such an architecture. It will be apparent to those skilled in the art that the embodiments can also be applied to other types of communication networks in which mobile communication principles are integrated with D2D (Device-to-Device) or V2X (Vehicle-to-Everything) configurations, SL (Sidelink), etc., for example, systems using Wi-Fi, Worldwide Interoperability for Microwave Access (WiMAX), Bluetooth®, Personal Communications Services (PCS), ZigBee®, Wideband Code Division Multiple Access (WCDMA), Ultra-Wideband (UWB) technologies, Mobile Ad Hoc Networks (MANETs), wired access, etc. Furthermore, without loss of generality, the description of some example embodiments relates to a mobile communication network, but the principles of the present disclosure can be extended and applied to any other type of communication network, such as a wired communication network.

[0050] The following examples and embodiments should be understood as illustrative examples only. Although the specification may refer to "an," "one," or "some" examples or embodiments in several places, this does not necessarily mean that each such reference relates to the same example or embodiment or that a feature applies only to a single example or embodiment. Single features of various embodiments may also be combined to provide other embodiments. Furthermore, words such as "comprising" and "including" should be understood as not limiting the described embodiments to including only the referenced features; such examples and embodiments may also encompass features, structures, units, modules, etc. that are not specifically mentioned.

[0051] A basic system architecture of a (tele)communication network, including a mobile communication system, in which some example embodiments can be used, can include architectures of one or more communication networks, including a radio access network subsystem and a core network. Such architecture can include one or more communication network control elements or functions, access network elements, radio access network elements, access service network gateways or base transceiver stations such as base stations (BSs), access points (APs), Node Bs (NBs), eNBs or gNBs, distributed units (DUs) or centralized / centralized units (CUs) controlling their respective coverage areas or cells and having one or more communication stations, such as communication elements or functions, such as user devices or terminal devices, such as user equipments (UEs), or other devices with similar functionality, such as modem chipsets, chips, modules, etc., which can be part of or attached as a separate element to a station, element, function or application capable of communicating, such as a UE, element, function, etc., usable in a machine-to-machine communication architecture, and can communicate over one or more channels via one or more communication beams to transmit several types of data in multiple access domains. It may also include core network elements or network functions such as gateway network elements / functions, mobility management entities, mobile switching centers, servers, databases, etc.

[0052] The following description may provide further details of alternatives, modifications and variations, and the gNB may include a node that provides NR user plane and control plane protocol termination towards the UE and is connected via an NG interface with the 5GC, for example, in accordance with 3GPP TS38.300V16.6.0(2021-06) Section 3.2, which is incorporated by reference.

[0053] The gNB central unit (gNB-CU) includes, for example, a logical node that hosts the en-gNB RRC and PDCP protocols that control the operation of the gNB's RRC, SDAP, and PDCP protocols and one or more gNB-DUs. The gNB-CU terminates the F1 interface connected to the gNB-DU.

[0054] The gNB distributed unit (gNB-DU) comprises a logical node that hosts, for example, the RLC, MAC, and PHY layers of a gNB or en-gNB, and its operation is controlled in part by the gNB-CU. One gNB-DU supports one or more cells. One cell is supported by only one gNB-DU. The gNB-DU terminates the F1 interface connected to the gNB-CU.

[0055] The gNB-CU-Control Plane (gNB-CU-CP) comprises a logical node that hosts the RRC and control plane part of the PDCP protocol of the gNB-CU for e.g. the en-gNB or gNB. The gNB-CU-CP terminates the E1 interface connected to the gNB-CU-UP and the F1-C interface connected to the gNB-DU.

[0056] The gNB-CU-User Plane (gNB-CU-UP) includes, for example, a logical node that hosts the user plane portion of the PDCP protocol of the gNB-CU for the en-gNB and the user plane portion of the PDCP and SDAP protocols of the gNB-CU for the gNB. The gNB-CU-UP terminates the E1 interface connected to the gNB-CU-CP and the F1-U interface connected to the gNB-DU, for example, in accordance with 3GPP TS 38.401V16.6.0(2021-07) Section 3.1, which is incorporated by reference.

[0057] Differential functional division between central and distributed units is possible, e.g., called options. Option 1 (1A-shaped division) o This optional functional division is similar to the 1A architecture in DC: RRC is in the central unit; PDCP, RLC, MAC, physical layer and RF are in distributed units. Option 2 (3C-shaped division) o This optional functional division is similar to the 3C architecture in DC: RRC and PDCP are in the central unit; RLC, MAC, physical layer and RF are in the distributed units. Option 3 (RLC-to-RLC splitting) Low RLC (partial functions of RLC), MAC, physical layer and RF are in the distributed units. PDCP and high RLC (other partial functions of RLC) are in the central unit. Option 4 (RLC-MAC split) o MAC, physical layer and RF are in distributed units. PDCP and RLC are in central unit. Alternatively, for example, according to 3GPP TR38.801V14.0.0(2017-03), which is incorporated by reference.

[0058] The gNB supports various protocol layers, for example, Layer 1 (L1) - the physical layer.

[0059] Layer 2 (L2) of NR is divided into the following sublayers: Medium Access Control (MAC), Radio Link Control (RLC), Packet Data Convergence Protocol (PDCP), and Service Data Adaptation Protocol (SDAP), where, for example: The physical layer provides transport channels to the MAC sublayer. The MAC sublayer provides logical channels to the RLC sublayer. The RLC sublayer provides the ELC channel to the PDCP sublayer. The PDCP sublayer provides the radio bearer to the SDAP sublayer. The SDAP sublayer provides QoS flows to the 5GC. o Comp. refers to header compression and Segm. refers to segmentation. Control channels include (BCCH, PCCH).

[0060] Layer 3 (L3) includes, for example, Radio Resource Control (RRC), for example, according to 3GPP TS38.300V16.6.0(2021-06) Section 6, which is incorporated by reference. A RAN (Radio Access Network) node or network node may be, or a portion thereof may be implemented using a device having at least one processor and / or at least one memory (with computer-readable instructions (computer programs)) configured to support and / or deploy and / or process functionality and / or features related to a CU and / or DU, and / or at least one protocol (sub)layer of the RAN (Radio Access Network), e.g., Layer 2 and / or Layer 3. A central node may support Central Unit - Control Part (CU-CP) and / or Central Unit - User Part (CU-UP) functionality. A distributed node may support Distributed Unit (DU) functionality. A network node may be implemented or operate as a master node or a secondary node. A master node may include at least a central node and / or a distributed node. A secondary node may include at least a central node and / or a distributed node.

[0061] The gNB CU and gNB DU portions may be, for example, co-located or physically separated. The gNB DU may be further divided, for example, into two portions, one containing a processing unit and one containing an antenna. The central unit (CU) may also be referred to as a BBU / REC / RCC / C-RAN / V-RAN, O-RAN, or a portion thereof. The distributed unit (DU) may also be referred to as an RRH / RRU / RE / RU, or a portion thereof. Hereinafter, in various exemplary embodiments of the present disclosure, the CU-CP (or more generally, the CU) may also be referred to as a (first) network node supporting at least one of a central unit control plane function or a Layer 3 protocol of the radio access network, and similarly, the DU may also be referred to as a (second) network node supporting at least one of a distributed unit function or a Layer 2 protocol of the radio access network.

[0062] The gNB-DU supports one or more cells and can therefore act, for example, as a serving cell for a user equipment (UE).

[0063] User equipment (UE) may include wireless or mobile devices, devices with a radio interface connecting to a RAN (Radio Access Network), smartphones, in-vehicle devices, IoT devices, M2M devices, etc. Such UEs or devices may include at least one processor and at least one memory containing computer program code configured by the at least one processor to cause the device to perform certain operations, such as an RRC connection with the RAN. The UE may be configured, for example, to generate messages (e.g., including a cell ID) transmitted via radio to the RAN (e.g., to reach and communicate with a serving cell). The UE may generate, send, and receive RRC messages containing one or more RRC PDUs (Packet Data Units).

[0064] A UE may have various states (e.g., according to 3GPP TS38.331V16.5.0(2021-06) Sections 42.1 and 4.4, which are incorporated by reference).

[0065] A UE may, for example, be in either the RRC_CONNECTED or RRC_INACTIVE state when an RRC connection is established.

[0066] In the RRC_CONNECTED state, the UE: o AS context can be stored, ○ It is possible to transfer unicast data to and from the UE, A control channel associated with the shared data channel may be monitored to determine whether data is scheduled on the data channel; o Can provide channel quality and feedback information, o It is possible to perform nearby cell measurements and measurement reports.

[0067] The RRC protocol has the following main functions: RRC connection control, Measurement configuration and reporting, Establishment / modification / release of measurement configurations (e.g. inter-frequency, inter-frequency and inter-RAT measurements), o Setting up and releasing measurement gaps, Measurement report Includes.

[0068] The general functionality and interconnections of the described elements and functions, which also depend on the actual network type, are known to those skilled in the art and are described in the corresponding specifications, whereby a detailed description thereof will be omitted here for the sake of brevity. However, it should be noted that several additional network elements and signaling links may be available for communication between elements such as communication endpoints, functions or applications, communication network control elements such as servers, gateways, radio network controllers, and other elements of the same or other communication networks other than those described in detail herein below.

[0069] The communications network architecture considered in the example embodiments may also communicate with other networks, such as the Public Switched Telephone Network or the Internet. It should also be noted that the communications network may also support the use of cloud services for virtual network elements or functions, where virtual network portions of the telecommunications network may also be provided by non-cloud resources, e.g., internal networks. It should also be understood that the network elements of an access system, such as a core network, and / or the respective functions may be implemented by using any node, host, server, access node or entity, etc., suitable for such use. In general, the network functions may be implemented either as dedicated hardware network elements, as software instances running on dedicated hardware, or as virtualized functions initialized on a suitable platform, e.g., a cloud infrastructure.

[0070] Furthermore, network elements such as communication elements like UEs, terminal devices, control elements or functions such as access network elements like base stations / BSs, core network control elements or functions such as gNBs, radio network controllers, gateway elements, or other network elements or functions as described herein, and any other elements, functions or applications may be implemented by software, for example by a computer program product of a computer, and / or by hardware. To perform their respective processing, the devices, nodes, functions or network elements used accordingly may include several means, modules, units, components, etc. (not shown) required for control, processing and / or communication / signaling functions. Such means, modules, units and components may include, for example, one or more processors or processor units including one or more processing portions for executing instructions and / or programs and / or processing data; storage or memory units or means (e.g., ROM, RAM, EEPROM, etc.) for storing instructions, programs and / or data and acting as a working area for the processors or processing portions etc., input or interface means (e.g., floppy disk, CD-ROM, EEPROM, etc.) for inputting data and instructions by software; user interfaces (e.g., screens, keyboards, etc.) for providing a user with monitoring and editing capabilities; other interfaces or means for establishing links and / or connections under the control of a processor unit or portion (e.g., wired and wireless interface means, e.g., radio interface means including antenna units, etc., means forming radio communication portions, etc.); and each means forming an interface such as a radio communication portion may also be located at a remote site (e.g., radio head or radio station, etc.). It should be noted that in this specification, a processing portion should not be considered to represent only the physical portion of one or more processors, but may also be considered as a logical division of the processing tasks referred to that are performed by one or more processors.It should be appreciated that in accordance with some embodiments, a so-called "liquid" or flexible network concept may be utilized in which operations and functions of a network element, network function, or operations and functions of another entity of the network may be performed in a flexible manner by different entities or functions, such as nodes, hosts, or servers. In other words, the division of "labor" between the network elements, functions, or entities involved may vary on a case-by-case basis.

[0071] According to Release 16, a UE can be configured with a conditional handover (CHO) target cell configuration and at least one CHO execution condition to determine when to perform a handover to one or more prepared target cells. The condition is / is based on radio measurements of the serving cell and the target cell. In the CHO configuration, the target cell can reserve a Cell Radio Network Time Identifier (C-RNTI) and Contention-Free Radio Access (CFRA) resources for the UE. When the UE evaluates the CHO condition and the condition is valid for a particular target cell, the UE can apply the CHO configuration of the target cell and initiate random access to the target cell using the reserved CFRA resources. A UE can be configured with multiple conditions for multiple target cells.

[0072] Figure 1 illustrates an example implementation of a signaling diagram for CHO. CHO is designed to allow a UE to perform handover autonomously without the need for a serving cell and to trigger handover execution after receiving a measurement report from the UE.

[0073] In step S101, the UE sends a measurement report identifying potential neighboring cells for handover. In steps S102 to S108, in response to the measurements received in step S101, the source RAN node determines that the UE should be provided with a target cell that supports CHO. The source RAN node sends conditional handover requests to multiple target RAN nodes. In each CHO request message, the source node indicates the cells provided by the respective target nodes. The target RAN node performs admission control and sends a handover request ACK for the requested cell and the associated conditional configuration for this cell in response to the CHO request.

[0074] In step S109, the source RAN node sends an RRC reconfiguration message with conditional configurations related to CHO to the UE. The UE receives this message and continues data exchange with the source node. In steps S110 to S111, the UE evaluates the CHO conditions and executes the conditional configurations for CHO for which the conditions are valid. In steps S111 to S114, the UE executes CHO toward the selected target cell controlled by the target RAN node and ceases TX / RX with the source node. In step S115, the target RAN node indicates the success of the handover to the source RAN node. Finally, in step S116, user plane procedures such as data forwarding and path switching are subsequently completed.

[0075] In the case of dual connectivity (DC), the target node (target master node - MN) is assumed to prepare multiple secondary cell groups (SCGs) (in the same or different secondary nodes - SNs) upon receiving a conditional handover request from the source node (source MN). This means that:

[0076] Option 1 - Any of the target RAN nodes sends multiple conditional configurations, each conditional configuration including a primary cell (PCell) and a primary / secondary cell (PSCell) configuration as a response to a single HO request.

[0077] Option 2 - Alternatively, the target RAN node sends one conditional configuration of a PSCell and multiple conditional configurations of PSCells (which can be Conditional PSCell Change (CPC) or Conditional PSCell Addition (CPA)) in response to a single HO request.

[0078] In both of these options, the target node sends multiple conditional configurations in response to a single CHO request.

[0079] Typically, a UE is limited to having a maximum number of conditional configurations in a CHO (e.g., 8). However, the target node is not aware of the limitation at a given time point on the UE side considering the number of existing conditional configurations. For example, if a UE is already configured with 6 conditional configurations and the target node offers 4 or more conditional configurations, the source node must choose not to offer these configurations to the UE and not be entitled to them (the source node cannot tell which of the prepared PSCells is "more important", e.g., has a better radio connection). The target node also reserves resources that will never be used by the UE if the corresponding PSCell is not in use.

[0080] Therefore, generally speaking, the present disclosure proposes techniques / mechanisms to limit and control the number of conditional configurations that a target node can prepare through the CHO procedure.

[0081] To address at least some or all of the problems exemplified above, in accordance with some exemplary embodiments, the present disclosure generally proposes that a source node indicate to a target node how much conditional configuration it should send in response to a conditional handover request.

[0082] In a broad sense, this disclosure generally proposes two different possible exemplary methods for controlling the number of conditional configurations that a target node prepares through the CHO procedure.

[0083] According to some possible (but not limited to) implementations, the source MN triggers the addition of multiple candidate PSCells. For example, the source node indicates to the target node (possibly in the Conditional Handover Request message) the maximum number of conditional configurations that the target node is allowed to prepare and provide in the Handover Request ACK message. The target node (MN) can use this information to determine the number of target SNs it must contact and indicate to each target SN the number of PSCells prepared by the target SN. Thus, the target node uses this information to determine the total number of conditional configurations to be included in the Handover Acknowledgement message. This embodiment has the advantage that the identification of the CHO preparation can be maintained as in the case of Classic CHO preparation, using the UE ID and the target PCell. However, in this case, if the CHO is canceled, all prepared PSCells are also canceled, since the PSCell configurations are included in a single CHO configuration. Therefore, if a PSCell is no longer valid, the CHO must be canceled and re-prepared, or the complete CHO must be updated if one PSCell needs to be updated.

[0084] According to some other possible (but not limited to) implementations, multiple CHO configurations are requested consecutively, with a single PSCell configuration existing per CHO configuration. For example, the target node indicates that it can provide multiple conditional configurations in response to a conditional handover request, but sends a single conditional configuration (in the legacy CHO handover request ACK). To fetch additional conditional configurations, the source node sends additional handover requests for the same target PCell. If the source node decides to request additional configurations, it indicates to the target node using a new indication (e.g., a flag), e.g., a so-called "CHO-multiply," that a new CHO request for the same PCell does not release existing preparations for this PCell. This indication is needed to prevent the target node from releasing previous conditional configurations associated with this target PCell, as happens with classic CHO. In these embodiments, each PSCell configuration is in a separate CHO configuration, and each CHO configuration has the same PCell configuration. Since a source node can send multiple new CHO requests related to the same PCell, it must identify and match the response from the target node to the request. Therefore, some additional identifier for the response (e.g., CHO Request ACK) is required. This embodiment effectively extends the identification of CHO preparation so that the PSCell is now part of this. This deviates from legacy behavior, but in the future can enable, for example, CHO cancellation related to a specific PSCell.

[0085] In an embodiment, the UE may inform the network regarding the number of conditional configurations that the UE can support for conditional handover. The UE may include this information in an existing message or may send a separate message, for example to the source node.

[0086] FIG. 2 illustrates an example of a signaling / messaging flow diagram according to some example embodiments of the present disclosure.

[0087] Generally, it can be seen that in the exemplary embodiment of FIG. 2, the source MN (e.g., gNB) is configured to make a conditional handover decision.

[0088] In steps S201 and S202, the UE is configured with a measurement configuration and reports measurements of neighboring PCells and, if possible, PSCells to the source MN. In step S203, the source MN determines based on the measurements whether CHO preparation of the UE is necessary or desirable. At this time, the source MN may have received a message from the UE indicating the number of conditional configurations that the UE is allowed or can support. The source MN may also obtain this information from other sources.

[0089] The source MN maintains the number of conditional configurations allowed for the UE in step S204 and determines how many additional conditional configurations it can allocate to the UE. To determine the number of additional conditional configurations, the source MN may take into account the number of conditional PSCell change (CPC), conditional PSCell addition (CPA), conditional handover (CHO), and low layer mobility (LLM) configurations already configured in the UE. A conditional configuration is a PSCell / PCell configuration that applies to a condition.

[0090] In step S205, the source MN sends a conditional handover request message to the target NM, indicating the maximum number X of conditional configurations provided by the target MN for the UE. The conditional handover request message may include measurement reports received for the UE.

[0091] In the CHO request message, the source node may indicate a target primary cell (PCell) of the master cell group prepared by the respective target node.

[0092] The target node may receive the CHO request message and perform admission control on the received request.

[0093] In steps S206 and S207, based on measurements including measurements of candidate PSCells received from the source MN, the target MN determines the number of conditional configurations to be provided to the UE together with the conditional handover request ACK. The number of conditional configurations determined by the target MN can be equal to or less than X indicated in step S205. The target MN determines to indicate the number of PSCells to be prepared by the target SN or multiple target SNs through corresponding SN addition requests. The SN addition request may include a list of PSCells (PSCell-1, PSCell-2, ..., PSCell-X) to be prepared for handover by each SN. The target SN prepares the maximum indicated number of PSCells and sends an SN addition request ACK message to the target MN (step S207). The target MN can send SN addition requests to various target SNs. The target MN can collect responses from various target SNs.

[0094] The target MN prepares the conditional configurations received from the SN and, if possible, the conditions for executing each target PSCell configuration, and sends them to the source MN together with a conditional handover request ACK (step S208). The target MN can explicitly indicate the number of conditional configurations to the source MN.

[0095] Each conditional configuration can be provided with a unique identifier ID. The ID is a unique identifier to distinguish which CHO indicates the same PCell, since multiple CHOs may be provisioned for the same PCell with various PSCells. Using the UE ID and PCell ID is not sufficient, since the proposed CHOs are for the same UE and the same PCell, but are associated with different PSCells. If all PSCell configurations are in the same CHO configuration, the UE ID and PCell ID are sufficient to indicate a single CHO configuration.

[0096] In step S209, the source MN updates the number of conditional configurations that the UE is currently configured with. In one embodiment, the source MN uses the number of conditional configurations explicitly indicated by the target MN in the conditional handover request ACK. In another embodiment, the source MN observes or decodes the configurations provided by the target MN to determine the number of conditional configurations.

[0097] In steps S210 to S217, the UE is configured with the conditional configuration (e.g., with an RRC reconfiguration message). The UE receives this message, sends an acknowledgement message (e.g., RRC reconfiguration completed in step S211), continues data exchange with the source node, and begins monitoring the condition for conditional handover. Once the condition is met (as determined in step S212), the UE continues to perform PCell modification and PSCell addition / modification in the same manner as described in Figure 1 (where step S213 in Figure 2 corresponds to steps S112 and S113 in Figure 1, S214 in Figure 2 corresponds to steps S114 and S115 in Figure 1, and Figure 2 includes PSCell access compared to Figure 1).

[0098] 3 illustrates another example of a signaling / messaging flow diagram according to some example embodiments of the present disclosure. This diagram is a condensed flow diagram that skips interactions with the UE so as not to show the redundant steps illustrated by FIG. 2, particularly the modified steps S205 and S209 of the previous embodiment (i.e., extending the CHO preparation phase).

[0099] The source MN may also have information related to the number of conditional configurations that the UE is authorized to support or that the UE can support, for example, the source MN may have received a message from the UE indicating the number of conditional configurations that the UE is authorized to support or that the UE can support.

[0100] In step S301, the source MN sends a conditional handover request to the target MN (compare step S205). As before, the handover request may include measurement reports of neighboring PCells and possibly PSCells, and the identity of the PCell prepared by the target MN.

[0101] In steps S302-S303, the target MN sends an SN Addition Request to one or more target SNs, and each target SN sends an SN Addition Request ACK message. If multiple SNs are involved, the target MN may decide to add a configuration from one PSCell to the UE. The SN Addition Request and SN Addition Request ACK are each for a single PSCell and may indicate the requested PSCell. In other words, the SN Addition Request ACK may include the requested PSCell configuration.

[0102] The target SN determines the number of PSCells that can be added from the measurements received from the target MN. For this purpose, the target MN can forward measurement reports to the target SN. Alternatively, further inputs such as OAM configurations can be used on the target SN side to determine the PSCells that can be added.

[0103] The target SN may indicate this to the target MN in an SN Addition Request ACK message. Alternatively, the target MN may determine that multiple target PSCells can be provisioned for the same target PCell based on measurements received from the source MN.

[0104] In step S304, the target MN determines, based on measurements or SN Addition Request ACK messages, that multiple PSCells can be added to the same target PCell and are potential target PSCells.

[0105] In step S305, the target MN sends a conditional handover request ACK to the source MN with conditional configurations of the target SN's PSCells to indicate to the source MN that it intends (i.e. is able) to send one or more further conditional configurations to other PSCells. The target MN indicates a unique identifier ID for each conditional configuration (compare step S208).

[0106] In step S306, the source MN determines whether the UE can be allocated further conditional configurations. To this end, the source MN compares the maximum allowed number of conditional configurations with the actual number of conditional configurations configured in the UE. If it is determined that the UE can accommodate one or more additional conditional configurations, the procedure continues to step S307.

[0107] In step S307, the source MN sends a new conditional handover request to the target MN, adding an indication (or flag) "CHO-multiply" to the request that the target MN maintains the previous conditional configuration and sends a new conditional configuration. The handover request may include measurement reports and indications for the PCell.

[0108] The target MN decides to maintain the previous CHO preparation and send another CHO conditional configuration to the source MN in step 308. The target MN decides to add another PSCell for CHO to the same PCell. The target MN sends an SN addition request to the target SN and receives an SN addition request ACK with the PSCell conditional configuration (steps S309 and S310). In step S311, the target MN sends a conditional handover request ACK to the source MN with an additional conditional configuration for the additional PSCell of the target SN.

[0109] Generally, a CHO configuration is associated with a PCell and a PSCell. The PCell is a kind of anchor for the CHO configuration. For example, the CHO configuration for PCell1 and PSCell1 is provided by a first conditional handover request ACK in step S305. Then, the CHO configuration for PCell1 and PSCell2 is provided by a second conditional handover request ACK in step S311. Thus, in response to a further CHO request (e.g., "CHO-Multiply") marked with an indication to maintain the previous conditional configuration and transmit a new conditional configuration, conditional configurations for the same PCell but for different PSCells are provided by the target MN in further conditional handover request ACKs.

[0110] The procedure may be repeated in step S306 to add further conditional configurations by the source MN, possibly with different target MNs and / or different target SNs, until the required number of conditional configurations has been collected. The procedure may continue similar to step S210 with the configuration of the UE and the execution of the conditional handover by the UE (steps S212 to S217).

[0111] To summarize the above, the present disclosure provides a technique / mechanism to limit and control the number of conditional configurations that a target node can prepare through the CHO procedure. The present disclosure generally proposes that the source node indicates to the target node the number of conditional configurations to be sent in response to the conditional handover request. Alternatively, the source node can send multiple conditional handover requests to the target node to retrieve the conditional configurations one by one.

[0112] Finally, it should be noted that while in the exemplary embodiments illustrated above (with respect to the figures), messages transmitted / exchanged between network components / elements are shown to have specific / explicit names depending on various implementations, these messages may have different names and / or be transmitted / exchanged in different forms / formats, as will be understood and appreciated by those skilled in the art.

[0113] According to some example embodiments, corresponding methods suitable to be performed by such devices (network elements / components), such as a UE, a source MN, a target MN, a target SN, etc., are also provided.

[0114] It should also be noted that the above-described apparatus (device) features correspond to respective method features that are not explicitly described for the sake of brevity. The disclosure of this document is intended to extend to such method features as well. In particular, the disclosure should be understood to relate to methods of operating the above-described devices and / or providing and / or arranging the respective elements of these devices.

[0115] Additionally, according to some further exemplary embodiments, there is also provided a respective device (e.g., implementing a UE, source MN, target MN, target SN, etc., as described above) that includes at least one processing circuit and at least one memory for storing instructions executed by the processing circuit, the at least one memory and instructions configured by the at least one processing circuit to cause the respective device to perform the respective steps as described above.

[0116] In some other example embodiments, there is also provided a respective apparatus (e.g., implementing a UE, a source MN, a target MN, a target SN, etc., as described above) that includes respective means configured to perform at least the respective steps as described above.

[0117] It should be noted that the exemplary embodiments of the present disclosure can be used in a variety of different network configurations. In other words, the exemplary embodiments shown in the above figures, which are used as the basis for the above-described exemplary embodiments, are merely illustrative and do not limit the present disclosure in any way. That is, additional existing and proposed new functions available in the corresponding operating environment can be used in connection with the exemplary embodiments of the present disclosure based on the defined principles.

[0118] It should also be noted that the disclosed exemplary embodiments can be implemented in many ways using hardware and / or software configurations. For example, the disclosed embodiments can be implemented using dedicated hardware and / or hardware in conjunction with software running on the hardware. The components and / or elements in the figures are examples only and do not limit the scope of use or functionality of any hardware, software in combination with hardware, firmware, embedded logic components, or combinations of two or more of these components to implement particular embodiments of the present disclosure.

[0119] It should be further noted that the description and drawings merely illustrate the principles of the present disclosure. Those skilled in the art will be able to implement various configurations not explicitly described or shown herein, which embody the principles of the present disclosure and are included within the spirit and scope of the present disclosure. Furthermore, all examples and embodiments outlined in this disclosure are expressly intended for illustrative purposes only to aid the reader in understanding the principles of the proposed method. Furthermore, all statements herein providing principles, aspects, and embodiments of the present disclosure, as well as specific examples thereof, are intended to encompass equivalents thereof. [Explanation of symbols]

[0120] S201 Measurement Control S202 Measurement Report S203 C. Handover decision S204 Maintain the number of conditional configurations for the UE S205 Handover Request (CHO) Measurement Report Maximum "X" conditional configuration S206 SN addition request PSCell-1, PSCell-2, PSCell-X S207 SN addition request ACK PSCell-1, PSCell-2, PSCell-X S208 Handover Request (CHO) ACK Each condition configuration with an ID S209 Update the number of conditional configurations for the UE S210 RRC reconfiguration C. Handover Command S211 RRC reconfiguration completed S212 CHO conditions apply S213 RACH S214 RRC reconfiguration S215 PSCell Radio Condition Evaluation S216 RACH

Claims

1. A first network node configured to support establishment of a connection towards a user equipment (UE) via a radio access network, the first network node comprising: The first network node at least one processor; at least one memory for storing instructions; Equipped with The instructions, when executed by the at least one processor, cause the first network node to at least: - deciding to prepare a conditional handover for the UE towards a second network node based on measurements performed by the UE; sending a conditional handover request for the UE towards the second network node, the conditional handover request including an indication related to a number of conditional configurations for which the second network node is allowed to prepare the handover; receiving a conditional handover request acknowledgement from the second network node, the conditional handover request acknowledgement including at least one conditional configuration related to at least one target cell for the handover; A first network node that causes

2. the network node is configured to maintain a number of conditional configurations allocated to the UE and to update said number after receiving the conditional handover request acknowledgment. The first network node of claim 1 .

3. the network node is configured to determine a maximum number of conditional configurations allocable and / or supported by the UE. A first network node according to claim 1 or 2.

4. the network node is configured to send a conditional handover request for the UE towards a third network node, the conditional handover request including an indication related to a number of conditional configurations for which the third network node is permitted to prepare the handover, the number being coordinated with the number sent to the second node and a maximum number supported by the user equipment. The first network node according to claim 3 .

5. The network node configured to transmit, towards the UE, a message including an indication related to the received at least one conditional configuration associated with at least one target cell of the second network node. A first network node according to any one of claims 1 to 4.

6. the conditional handover request acknowledgment includes a number of at least one conditional configuration included in the conditional handover request acknowledgment. A first network node according to any one of claims 1 to 5.

7. 1. A first network node configured to support establishment of a connection towards a user equipment (UE) via a radio access network, the first network node comprising: at least one processor; at least one memory for storing instructions; Equipped with The instructions, when executed by the at least one processor, cause the first network node to at least: determining to prepare a conditional handover for the UE towards a second network node based on measurements performed by the UE; sending a conditional handover request for the UE towards the second network node; receiving a conditional handover request acknowledgement from the second network node, the conditional handover request acknowledgement including an indication that at least one additional conditional configuration associated with one or more further target cells is available for the handover; A first network node that causes

8. the first network node is configured to determine whether it can allocate at least one or more conditional configurations to the UE, and in that case to send a further conditional handover request to the second network node to obtain another conditional configuration associated with a further target cell. The first network node of claim 7.

9. the further conditional handover request includes an indication that the second network node will not release the existing provision of a target cell and will return another conditional configuration relating to the further target cell in a further conditional handover request acknowledgement. The first network node according to claim 8 .

10. the conditional handover request acknowledgment includes a conditional configuration for a primary cell of a primary cell group and a primary cell of a secondary cell group, and the other conditional handover request acknowledgment includes a conditional configuration for another primary cell of a secondary cell group; The first network node of claim 9.

11. the conditional handover request acknowledgment includes a conditional configuration for a primary cell of a primary cell group and a primary cell of a secondary cell group, and the other conditional handover request acknowledgment includes a conditional configuration for another primary cell of a secondary cell group and the same primary cell of the primary cell group; The first network node of claim 9.

12. The first network node Compiling a different conditional handover request acknowledgement for the same UE with the received conditional configuration; transmitting a message towards the UE including an indication related to the compiled at least one conditional configuration related to at least one target cell of the second network node; A first network node according to any one of claims 8 to 11, configured to:

13. the conditional handover request acknowledgment includes a unique identifier associated with a conditional configuration included in the conditional handover request acknowledgment. A first network node according to any one of claims 1 to 12.

14. the conditional handover request comprises a request to prepare a conditional handover towards the second network node and a secondary node; The first network node further comprises: receiving a conditional handover request acknowledgement from the second network node, the conditional handover request acknowledgement including at least one conditional configuration relating to at least one target cell of the second network node and at least one secondary cell of the secondary node; A first network node according to any one of claims 1 to 13, configured to:

15. the first network node is a source master node of dual connectivity of the UE in the radio access network, the second network node is a target master node of dual connectivity of the UE, the conditional handover request includes an indication of a primary cell (PCell) associated with the second network node, and the conditional handover request acknowledgment includes one or more indications of secondary cells (PSCells) associated with the secondary node; The first network node of claim 14.

16. The first network node configured to receive from the UE an indication of the number of conditional configurations for conditional handover that the UE can support. A first network node according to any one of claims 1 to 16.

17. a second network node configured to support establishment of a connection towards a user equipment (UE) via a radio access network, the second network node comprising: at least one processor; at least one memory for storing instructions; Equipped with The instructions, when executed by the at least one processor, cause the second network node to receiving a conditional handover request for the UE from a first network node, the conditional handover request including an indication related to a number of conditional configurations for which the second network node is permitted to prepare the handover; determining, based on the received conditional handover request, that a plurality of target cells controlled by the second network are to be prepared for the handover; sending a conditional handover request acknowledgement towards the first network node, the conditional handover request acknowledgement including at least one conditional configuration related to at least one target cell for the handover; a second network node that causes the

18. the received conditional handover request includes information about radio measurements of a target cell made by the UE; The second network node 18. The second network node of claim 17, configured to determine potentially available target cells and the number of respective conditional configurations for the conditional handover request based on the radio measurements and the number of conditional configurations for which the second network node is authorized to prepare the handover.

19. The second network node sending a request to a secondary node to prepare a plurality of target cells for the handover; receiving an acknowledgement from the secondary node including a conditional configuration for the prepared target cell; 18. The second network node according to claim 17, configured to:

20. 20. The second network node of claim 19, wherein the second network node is a target master node for dual connectivity of the UE in the radio access network, the request to prepare multiple target cells is a request to add a secondary node (SN), the conditional handover request includes an indication of a primary cell (PCel1) associated with the second network node, and the conditional handover request acknowledgement includes one or more indications of secondary cells (PSCells) associated with the secondary node.

21. a second network node configured to support establishment of a connection towards a user equipment (UE) via a radio access network, the second network node comprising: at least one processor; at least one memory for storing instructions; Equipped with The instructions, when executed by the at least one processor, cause the second network node to receiving a conditional handover request for the UE from a first network node, the conditional handover request including information about radio measurements of a target cell made by the UE; determining that a plurality of target cells controlled by the second network node are to be prepared for the handover; sending a conditional handover request acknowledgement towards the first network node comprising an indication that at least one additional conditional configuration of one or more further target cells is available for the handover; a second network node that causes the

22. determining that a plurality of target cells associated with the second network node are potentially available for the handover is based on information relating to radio measurements of the target cells; 22. The second network node of claim 21.

23. the second network node sending a request to a secondary node to prepare a target cell for the handover, the request to prepare the target cell including at least part of the received information on radio measurements of the target cell; receiving an acknowledgement from the secondary node including a conditional configuration for the prepared target cell, the acknowledgement including an indication that multiple target cells controlled by the secondary node are potentially available for the handover; configured to:

22. The second network node of claim 21.

24. The second network node receiving a further conditional handover request from the first network node including an indication that the second network node will not release the existing provision of the target cell and return another conditional configuration of the further target cell in another conditional handover request acknowledgement; The second network node according to any one of claims 21 to 23, configured to:

25. The second network node determining to add a further target cell for the handover by sending another request to the secondary node to prepare the further target cell for the handover and receiving another acknowledgement from the secondary node including a conditional configuration for the prepared further target cell; sending another conditional handover request acknowledgement to the first network node, the conditional handover request acknowledgement including a conditional configuration for the further target cell; 25. The second network node of claim 24, configured to:

26. the conditional handover request acknowledgment includes a unique identifier associated with a conditional configuration included in the conditional handover request acknowledgment. A second network node according to any one of claims 21 to 25.

27. 24. The second network node of claim 23, wherein the second network node is a target master node of dual connectivity of the UE in the radio access network, the request to prepare the target cell is a request to add a secondary node (SN), the conditional handover request includes an indication of a primary cell (PCell) associated with the second network node, and the conditional handover request acknowledgment includes one or more indications of secondary cells (PSCells) associated with the secondary node.

28. 1. A user equipment (UE) configured to operate in a radio access network, comprising: at least one processor; at least one memory for storing instructions; Equipped with The instructions, when executed by the at least one processor, cause the UE to at least: indicating to the network the number of conditional configurations for conditional handover that the UE can support; transmitting measurements of a target cell for a potential handover towards a network node; receiving a message for conditional handover from the network node, the message including an indication related to at least one conditional configuration associated with at least one of the target cells; A user equipment (UE) that performs the above.

29. 29. The user equipment of claim 28, configured to evaluate the at least one conditional configuration and, if at least one condition holds, perform a handover towards the target cell associated with the satisfied condition.

30. A first network node according to any one of claims 1 to 16; A user equipment (UE) according to claim 28 or claim 29, served by a cell of the first network node; and A system comprising:

31. 1. A method of a first network node configured to support establishment of a connection towards a user equipment (UE) via a radio access network, the method comprising: determining to prepare a conditional handover for the UE towards a second network node based on measurements performed by the UE; sending a conditional handover request for the UE towards the second network node, the conditional handover request including an indication related to a number of conditional configurations for which the second network node is allowed to prepare the handover; receiving a conditional handover request acknowledgement from the second network node, the conditional handover request acknowledgement including at least one conditional configuration related to at least one target cell for the handover; A method comprising:

32. 1. A method of a first network node configured to support establishment of a connection towards a user equipment (UE) via a radio access network, the method comprising: - determining to prepare a conditional handover for the UE towards a second network node based on measurements performed by the UE; sending a conditional handover request for the UE towards the second network node; receiving a conditional handover request acknowledgement from the second network node, the conditional handover request acknowledgement including an indication that at least one additional conditional configuration associated with one or more further target cells is available for the handover; A method comprising:

33. 1. A method of a second network node configured to support establishment of a connection towards a user equipment (UE) via a radio access network, the method comprising: receiving a conditional handover request for the UE from a first network node, the conditional handover request including an indication related to a number of conditional configurations for which the second network node is permitted to prepare the handover; determining, based on the received conditional handover request, a plurality of target cells controlled by the second network node to be prepared for the handover; sending a conditional handover request acknowledgement towards the first network node, the conditional handover request acknowledgement including at least one conditional configuration related to at least one target cell for the handover; A method comprising:

34. 1. A method of a second network node configured to support establishment of a connection towards a user equipment (UE) via a radio access network, the method comprising: receiving a conditional handover request for the UE from a first network node, the conditional handover request including information about radio measurements of a target cell made by the UE; determining that a plurality of target cells controlled by the second network node are to be prepared for the handover; sending a conditional handover request acknowledgement towards the first network node comprising an indication that at least one additional conditional configuration of one or more further target cells is available for the handover; A method comprising:

35. 1. A method of user equipment (UE) configured to operate in a radio access network, comprising: indicating to the network the number of conditional configurations for conditional handover that the UE can support; transmitting measurements of a target cell of a potential handover towards a network node; receiving a message for conditional handover from the network node, the message including an indication related to at least one conditional configuration associated with at least one of the target cells; A method comprising:

36. A computer program comprising instructions for causing an apparatus to carry out the method according to any one of claims 31 to 35.

37. A memory storing computer readable instructions for causing an apparatus to carry out a method according to any one of claims 31 to 35.

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