Multiple condition configurations for same handover request

Abstract

Described herein is a first network node that controls a source cell of a user equipment (UE) in a radio access network, the first network node being a master node for carrier aggregation or dual connectivity of 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 at least: determine a conditional handover of a UE served by the source cell; sending a conditional switching request for the UE to a second network node that controls a potential target cell of the UE in the radio access network, the second network node being a target master node for carrier aggregation or dual connectivity of the UE; receiving a conditional handover request acknowledgement from the second network node, the conditional handover request acknowledgement comprising at least one conditional configuration of a handover target cell; and maintaining a number of condition configurations for the UE.

Description

Technical Field

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

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

[0003] In Rel.16, conditional handover (CHO) was introduced. The user equipment (UE) is configured with a CHO target cell configuration and at least one CHO execution condition in order to decide when to perform a handover to one or more prepared target cells. When the UE evaluates the CHO condition and the condition holds for a specific target cell, the UE applies the CHO configuration of the target cell and switches to the target cell. Currently, the UE is limited to considering a maximum of 8 condition configurations in CHO.

[0004] In the CHO process, the target radio access network (RAN) node does not know the number of conditional configurations that already exist on the UE side, and sends multiple conditional configurations for the primary cell (PSCell) in the secondary cell group to the source RAN node as a response to a single CHO request. On the other hand, the source node does not know which of the prepared PSCells has better radio conditions and is more important. Therefore, the source node cannot select the best PSCell and its corresponding conditional configuration to present to the UE.

[0005] Therefore, there is a need to limit and control the number of conditional configurations of CHO provided to the UE. Summary of the invention

[0006] According to one aspect of the present disclosure, a first network node is provided, which is configured to support establishing a connection to a user equipment UE via a radio access network, and the first network node includes: at least one processor; and at least one memory storing instructions, which instructions, when executed by the at least one processor, enable the first network node to at least: determine, based on measurements performed by the UE, to prepare for conditional handover of the UE to a second network node; send a conditional handover request for the UE to the second network node, wherein the conditional handover request includes an indication related to: the number of conditional configurations prepared by the second network node for handover permission; and receive a conditional handover request confirmation from the second network node, wherein the conditional handover request confirmation includes at least one conditional configuration related to at least one target cell for handover.

[0007] In some examples, the network node is configured to maintain a certain number of conditional configurations assigned to the UE and update the number after receiving the conditional handover request confirmation.

[0008] In some examples, the network node is configured to determine a maximum number of conditional configurations allocable to and / or supported by the UE.

[0009] In some examples, the network node is configured to: send a conditional handover request for the UE to a third network node, wherein the conditional handover request includes an indication related to: a number of conditional configurations prepared by the third network node for handover permission, wherein the number is coordinated with the number sent to the second node and the maximum number supported by the user equipment.

[0010] In some examples, the network node is configured to send a message to the UE, the message 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 examples, the conditional handover request confirmation includes a certain number of at least one condition configuration included in the conditional handover request confirmation.

[0012] According to one aspect of the present disclosure, a first network node is provided, which is configured to support establishing a connection to a user equipment UE via a wireless access network, and the first network node includes: at least one processor; and at least one memory storing instructions, which instructions, when executed by the at least one processor, enable the first network node to at least: determine preparations for conditional handover of the UE to a second network node based on measurements performed by the UE; send a conditional handover request for the UE to the second network node; and receive a conditional handover request confirmation from the second network node, the conditional handover request confirmation including the following indication: at least one additional condition configuration related to one or more additional target cells is available for handover.

[0013] In some examples, the first network node is configured to determine whether the UE can be assigned at least one more conditional configuration, and in this case, send a further conditional handover request to the second network node to obtain another conditional configuration related to a further target cell.

[0014] In some examples, the further conditional handover request includes an indication that the second network node should not release existing preparations for the target cell and returns another conditional configuration related to the further target cell (PSCell-2) in a further conditional handover request acknowledgment.

[0015] In some examples, the conditional handover request confirmation includes conditional configurations for a primary cell in the primary cell group and a primary cell in the secondary cell group, and the another conditional handover request confirmation includes conditional configurations for another primary cell in the secondary cell group.

[0016] In some examples, the conditional handover request confirmation includes conditional configurations for a primary cell in a primary cell group and a primary cell in a secondary cell group, and the other conditional handover request confirmation includes conditional configurations for another primary cell in the secondary cell group and the same primary cell in the primary cell group.

[0017] In some examples, the first network node is configured to: aggregate conditional configurations received using different conditional handover request confirmations for the same UE, and send a message to the UE, the message including an indication related to: at least one aggregated conditional configuration related to at least one target cell of the second network node.

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

[0019] In some examples, the conditional handover request includes a request to prepare a conditional handover to a second network node and a secondary node, wherein the first network node is further configured to: receive a conditional handover request confirmation from the second network node, the conditional handover request confirmation including at least one conditional configuration related to at least one target cell of the second network node and at least one secondary cell of the secondary node.

[0020] In some examples, the first network node is a source master node for dual connectivity of a UE in a wireless access network, the second network node is a target master node for dual connectivity of the UE, the conditional switching request includes an indication of a primary cell PCell associated with the second network node, and the conditional switching request confirmation includes one or more indications of a secondary cell PSCell associated with the secondary node.

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

[0022] According to one aspect of the present disclosure, a second network node is provided, which is configured to support establishing a connection to a user equipment UE via a radio access network, and the second network node includes: at least one processor; and at least one memory storing instructions, which instructions, when executed by the at least one processor, enable 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: the number of conditional configurations that the second network node is allowed to prepare for handover; determine, based on the received conditional handover request, a plurality of target cells to be controlled by the second network node to be prepared for handover; and send a conditional handover request confirmation to the first network node, the conditional handover request confirmation including at least one conditional configuration related to at least one target cell for handover.

[0023] In some examples, the received conditional handover request includes information about radio measurements performed by the UE on the target cell, and the second network node is configured to: determine a certain number of target cells potentially available for the conditional handover request and the corresponding conditional configurations for this number based on the radio measurements and the number of conditional configurations prepared by the second network node for handover permission.

[0024] In some examples, the second network node is configured to: send a request to the secondary node to prepare a plurality of target cells for handover; and receive a confirmation from the secondary node, the confirmation including a conditional configuration for the prepared target cells.

[0025] In some examples, the second network node is a target primary node for dual connectivity of a UE in a wireless access network, the request for preparing multiple target cells is a secondary node SN add request, and the conditional switching request includes an indication of a primary cell PCell associated with the second network node, and the conditional switching request confirmation includes one or more indications of a secondary cell PSCell associated with the secondary node.

[0026] According to one aspect of the present disclosure, a second network node is provided, which is configured to support establishing a connection to a user equipment UE via a wireless access network, and the second network node includes: at least one processor; and at least one memory storing instructions, which instructions, when executed by the at least one processor, enable 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 performed by the UE on a target cell; determine a plurality of target cells to be prepared for handover to be controlled by the second network node; and send a conditional handover request confirmation to the first network node, the conditional handover request confirmation including an indication that at least one additional condition configuration for one or more additional target cells is available for handover.

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

[0028] In some examples, the second network node is configured to: send a request to the secondary node for preparing a target cell for switching, the request for preparing the target cell including at least a portion of the received information about radio measurements for the target cell; and receive a confirmation from the secondary node, the confirmation including a conditional configuration for the prepared target cell, the confirmation including an indication that multiple target cells controlled by the secondary node are potentially available for switching.

[0029] In some examples, the second network node is configured to: receive a further conditional handover request from the first network node, the further conditional handover request including an indication that the second network node should not release existing preparations for the target cell, and return another conditional configuration of the further target cell in another conditional handover request confirmation.

[0030] In some examples, the second network node is configured to: determine to add an additional target cell for switching by: sending another request to the secondary node to prepare an additional target cell for switching, and receiving another confirmation from the secondary node, the other confirmation including a conditional configuration for the prepared additional target cell; and sending another conditional switching request confirmation to the first network node, the other conditional switching request confirmation including the conditional configuration of the additional target cell.

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

[0032] In some examples, the second network node is a target primary node for dual connectivity of a UE in a wireless access network, the request for preparing the target cell is a secondary node SN add request, and the conditional switching request includes an indication of a primary cell PCell associated with the second network node, and the conditional switching request confirmation includes one or more indications of a secondary cell PSCell associated with the secondary node.

[0033] According to one aspect of the present disclosure, a user equipment (UE) is provided, which is configured to operate in a wireless access network, and includes: at least one processor; and at least one memory storing instructions, which, when executed by the at least one processor, enables the UE to at least: indicate to the network: the number of conditional configurations for conditional switching that the UE can support; send measurements for target cells for potential switching to a network node; and receive a message for conditional switching from the network node, the message including indications related to: at least one conditional configuration related to at least one of the target cells.

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

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

[0036] According to one aspect of the present disclosure, a method of a first network node is provided, the first network node being configured to support establishing a connection to a user equipment UE via a radio access network, the method comprising: determining, based on measurements performed by the UE, preparation for conditional handover of the UE to a second network node; sending a conditional handover request for the UE to the second network node, wherein the conditional handover request comprises an indication related to: the number of conditional configurations that the second network node has prepared for handover permission; and receiving a conditional handover request confirmation from the second network node, the conditional handover request confirmation comprising at least one conditional configuration related to at least one target cell for handover.

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

[0038] According to one aspect of the present disclosure, a method for a second network node is provided, the second network node being configured to support establishing a connection to 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 comprising an indication related to: the number of conditional configurations that the second network node is allowed to prepare for handover; determining, based on the received conditional handover request, a plurality of target cells to be controlled by the second network node to be prepared for handover; and sending a conditional handover request confirmation to the first network node, the conditional handover request confirmation comprising at least one conditional configuration related to at least one target cell for handover.

[0039] According to one aspect of the present disclosure, a method of a second network node is provided, the second network node being configured to support establishing a connection to 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 comprising information about radio measurements performed by the UE on a target cell; determining a plurality of target cells to be prepared for handover to be controlled by the second network node; and sending a conditional handover request confirmation to the first network node, the conditional handover request confirmation comprising an indication that at least one additional conditional configuration for one or more additional target cells is available for handover.

[0040] According to one aspect of the present disclosure, a method for a user equipment (UE) is provided, wherein the UE is configured to operate in a wireless access network, the method comprising: indicating to a network: the number of conditional configurations for conditional switching that the UE can support; sending measurements for a target cell for potential switching to a network node; and receiving a message for conditional switching from the network node, the message comprising an indication related to: at least one conditional configuration related to at least one of the target cells.

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

[0042] In addition, according to some other example embodiments, for example, a computer program product for a wireless communication device is provided, the wireless communication device comprising at least one processor, the at least one processor comprising a software code portion, the software code portion being used to perform the corresponding steps disclosed in the present disclosure when the above-mentioned product is run on the device. The computer program product may include a computer-readable medium having the above-mentioned software code portion stored thereon. In addition, the computer program product may be directly loadable into the internal memory of the computer and / or transmittable via a network by means of at least one of an upload, download, and push process.

[0043] Although some example embodiments will be described herein with particular reference to the above-mentioned applications, it will be appreciated that the present disclosure is not limited to such fields of use and is applicable in a wider context.

[0044] It is worth noting that it should be understood that the method according to the present disclosure relates to a method of operating a device according to the above-mentioned example embodiments and variations thereof, and corresponding statements made about the device are also applicable to the corresponding method, and vice versa, so similar descriptions may be omitted for the sake of brevity. In addition, even if not explicitly disclosed, the above aspects may be combined in a variety of ways. Those skilled in the art will understand that these aspects and feature / step combinations are possible unless it produces a contradiction that is explicitly excluded.

[0045] Implementation of the disclosed apparatus may include the use of, but is not limited to, one or more processors, one or more application specific integrated circuits (ASICs), and / or one or more field programmable gate arrays (FPGAs). Implementation of the apparatus may also include the use of other conventional and / or custom hardware, such as a software programmable processor, such as a graphics processing unit (GPU) processor.

[0046] Other and further example embodiments of the present disclosure will become apparent during the following discussion and by reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0048] Figure 1 schematically illustrates an example of a signaling / messaging flow chart for conditional switching;

[0049] Figure 2 schematically illustrates an example of a signaling / message flow chart for conditional switching according to an example embodiment of the present disclosure;

[0050] Figure 3 Another example of a signaling / message flow chart for conditional switching according to an example embodiment of the present disclosure is schematically illustrated. DETAILED DESCRIPTION

[0051] In the following, different exemplary embodiments will be described using a communication network architecture based on 3GPP standards for communication networks (such as 5G / NR) as an example of an exemplary communication network to which the embodiments can be applied, without limiting the embodiments to such architectures. It is clear to those skilled in the art that the embodiments can also be applied to other types of communication networks in which the mobile communication principles are integrated with D2D (device to device) or V2X (vehicle to everything) configurations, such as SL (side link), e.g. Wi-Fi, Worldwide Interoperability for Microwave Access (WiMAX), Personal Communications Service (PCS), Wideband Code Division Multiple Access (WCDMA), systems using ultra-wideband (UWB) technology, mobile ad hoc networks (MANET), wired access, etc. In addition, without loss of generality, the description of some examples of the embodiments is related to mobile communication networks, 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.

[0052] 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 multiple places, this does not necessarily mean that each such reference is related to the same (multiple) examples or embodiments, nor does it necessarily mean that the feature only applies to a single example or embodiment. Individual features of different embodiments may also be combined to provide other embodiments. In addition, terms such as "comprising" and "including" should be understood as not limiting the described embodiments to only those features that have been mentioned; such examples and embodiments may also include features, structures, units, modules, etc. that are not specifically mentioned.

[0053] The basic system architecture of a communication (telecommunication) network including a mobile communication system (in which some examples of the embodiments are applicable) may include the architecture of one or more communication networks, including (multiple) radio access network subsystems and (multiple) core networks. Such an architecture may 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 (BS), access points (AP), NodeBs (NBs), eNBs or gNBs), distributed units (DUs) or centralized / central units (CUs), which control the corresponding coverage area or (multiple) cells and one or more communication stations (such as communication elements or functions, such as user equipment or terminal equipment, such as user equipment (UE), or another device with similar functions, such as a modem chipset, chip, module, etc., which may also be part of a station, element, function or application capable of communication, such as a UE, element or function that can be used for a machine-to-machine communication architecture, or as a separate element attached to an element, function or application capable of communication, etc.) through which it can communicate via one or more channels via one or more communication beams to send several types of data in multiple access domains. Furthermore, core network elements or network functions may be included, such as gateway network elements / functions, mobility management entities, mobile switching centers, servers, databases, etc.

[0054] The following description may provide further details of alternatives, modifications, and variations: The gNB includes, for example, a node that provides NR user plane and control plane protocol termination towards the UE and is connected to the 5GC via an NG interface, for example, in accordance with Section 3.2 of 3GPP TS 38.300 V16.6.0 (2021-06) incorporated by reference.

[0055] The gNB Central Unit (gNB-CU) comprises, for example, a logical node that hosts, for example, the RRC, SDAP and PDCP protocols of a gNB, or the RRC and PDCP protocols of an en-gNB that controls the operation of one or more gNB-DUs. The gNB-CU terminates the F1 interface connected to the gNB-DU.

[0056] The gNB distributed unit (gNB-DU) comprises, for example, a logical node that hosts, for example, the RLC, MAC, and PHY layers of a gNB or en-gNB, and whose operation is partially controlled 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.

[0057] The gNB-CU control plane (gNB-CU-CP) comprises, for example, a logical node that hosts the control plane portion of the RRC and PDCP protocols, for example, for a gNB-CU of an en-gNB or gNB. The gNB-CU-CP terminates the E1 interface with the gNB-CU-UP and the F1-C interface with the gNB-DU.

[0058] The gNB-CU user plane (gNB-CU-UP) includes, for example, a logical node that hosts, for example, the user plane part of the PDCP protocol for the gNB-CU of the en-gNB, and the user plane parts of the PDCP protocol and the SDAP protocol for the gNB-CU of 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, according to Section 3.1 of 3GPP TS 38.401 V16.6.0 (2021-07) incorporated by reference.

[0059] There can be different functional splits between central and distributed units, called options for example:

[0060] Option 1 (Class 1A Split):

[0061] The functional split in this option is similar to the 1A architecture in DC. RRC is located in the central unit. PDCP, RLC, MAC, physical layer and RF are located in the distributed unit.

[0062] Option 2 (Class 3C Split):

[0063] The functional split in this option is similar to the 3C architecture in DC. RRC and PDCP are located in the central unit. RLC, MAC, physical layer and RF are located in the distributed unit.

[0064] Option 3 (split within RLC):

[0065] • Low RLC (part of the RLC functions), MAC, physical layer and RF are located in the distributed unit. PDCP and High RLC (another part of the RLC functions) are located in the central unit.

[0066] Option 4 (RLC-MAC Split):

[0067] MAC, physical layer and RF are located in the distributed unit. PDCP and RLC are located in the central unit.

[0068] Otherwise, for example, according to 3GPP TR 38.801 V14.0.0 incorporated by reference

[0069] (2017-03) Section 11.

[0070] gNB supports different protocol layers, such as Layer 1 (L1) - the physical layer.

[0071] NR’s Layer 2 (L2) is split 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:

[0072] The physical layer provides transport channels to the MAC sublayer;

[0073] The MAC sublayer provides logical channels to the RLC sublayer;

[0074] The RLC sublayer provides RLC channels to the PDCP sublayer;

[0075] The PDCP sublayer provides radio bearers to the SDAP sublayer;

[0076] The SDAP sublayer provides QoS flows to the 5GC;

[0077] Comp. refers to header compression and Segm. refers to segmentation;

[0078] Control channels include (BCCH, PCCH).

[0079] Layer 3 (L3) includes, for example, Radio Resource Control (RRC), for example according to Section 6 of 3GPP TS 38.300 V16.6.0 (2021-06), incorporated by reference.

[0080] A RAN (Radio Access Network) node or network node (such as a gNB, base station, central node, distributed node, gNB CU or gNB DU or part thereof) may be implemented using, for example, a device having at least one processor and / or at least one memory (having computer-readable instructions (computer program)), the device being configured to support and / or provide and / or process CU and / or DU related functions and / or features, and / or at least one protocol (sub) layer of the RAN (Radio Access Network), such as 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) functions. A distributed node may support distributed unit (DU) functions.

[0081] A network node may be implemented as a primary node or a secondary node, or may be implemented to act as a primary node or a secondary node. A primary 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.

[0082] The gNB CU and gNB DU parts may be, for example, collocated or physically separated. The gNB DU may be even further split into two parts, for example, one part including a processing device and the other part including an antenna. The central unit (CU) may also be referred to as BBU / REC / RCC / C-RAN / V-RAN, O-RAN or a part thereof. The distributed unit (DU) may also be referred to as RRH / RRU / RE / RU or a part thereof. Hereinafter, in various exemplary embodiments of the present disclosure, the CU-CP (or more generally, CU) may also be referred to as a (first) network node supporting at least one of the central unit control plane functions or the Layer 3 protocols of the radio access network; and similarly, the DU may be referred to as a (second) network node supporting at least one of the distributed unit functions or the Layer 2 protocols of the radio access network.

[0083] The gNB-DU supports one or more cells and can thus serve as, for example, a serving cell for a user equipment (UE).

[0084] User equipment (UE) may include a wireless or mobile device, a device having a radio interface that interacts with a RAN (radio access network), a smartphone, an in-vehicle device, an IoT device, an M2M device, etc. Such a UE or device may include: at least one processor; and at least one memory, including computer program code; wherein the at least one memory and the computer program code are configured to, together with the at least one processor, cause the device to at least perform certain operations, such as an RRC connection with the RAN. The UE is, for example, configured to generate a message (e.g., including a cell ID) to be sent to the RAN via radio (e.g., to reach a serving cell and communicate with it). The UE may generate, send and receive an RRC message containing one or more RRC PDUs (packet data units).

[0085] The UE may have different states (e.g., according to sections 42.1 and 4.4 of 3GPP TS 38.331 V16.5.0 (2021-06), incorporated herein by reference).

[0086] When the RRC connection has been established, the UE is in, for example, an RRC_CONNECTED state or an RRC_INACTIVE state.

[0087] In the RRC_CONNECTED state, the UE can:

[0088] Store AS context;

[0089] Transmit unicast data to and from UE;

[0090] Monitor the control channel associated with the shared data channel to determine if it is data

[0091] Channel scheduling data;

[0092] Provide channel quality and feedback information;

[0093] Perform neighbor cell measurements and measurement reporting.

[0094] The RRC protocol includes the following main functions:

[0095] RRC connection control;

[0096] Measurement configuration and reporting;

[0097] · Establish / modify / publish measurement configurations (e.g., intra-frequency, inter-frequency, and inter-RAT)

[0098] Measurement);

[0099] ·Measure the establishment and release of the gap;

[0100] Measurement report.

[0101] The general functionality and interconnection of the described elements and functions (also depending on the actual network type) are known to those skilled in the art and are described in the corresponding specifications, so for the sake of brevity, a detailed description thereof may be omitted here. However, it should be noted that in addition to those described in detail below, several additional network elements and signaling links may be employed to communicate with elements, functions or applications (such as communication endpoints), communication network control elements (such as servers, gateways, radio network controllers), and other elements of the same or other communication networks.

[0102] The communication network architecture considered in the examples of embodiments may also be able to communicate with other networks such as a public switched telephone network or the Internet. The communication network may also support cloud services for virtual network elements or their functions, wherein it should be noted that the virtual network portion of the telecommunications network may also be provided by non-cloud resources, such as an internal network, etc. It should be understood that the network elements and / or corresponding functions of the access system, core network, etc. may be implemented by using any node, host, server, access node or entity, etc. suitable for such purpose. In general, the network functions may be implemented as network elements on dedicated hardware, software instances running on dedicated hardware, or virtualized functions instantiated on an appropriate platform (e.g., a cloud infrastructure).

[0103] In addition, network elements (such as communication elements, such as UE, terminal equipment, control elements or functions, such as access network elements, such as base stations / BS, gNB, radio network controllers, core network control elements or functions, such as gateway elements, or other network elements or functions described herein), and any other elements, functions or applications may be implemented by software, such as a computer program product of a computer; and / or by hardware. In order to perform its corresponding processing, the correspondingly used devices, nodes, functions or network elements may include several components, modules, units, components, etc. (not shown) required for control, processing and / or communication / signaling functions. For example, such components, modules, units and components may include one or more processors or processor units, including one or more processing parts for executing instructions and / or programs and / or for processing data, storage or memory units or components (e.g., ROM, RAM, EEPROM, etc.) for storing instructions, programs and / or data as work areas for processors or processing parts, input or interface components for inputting data and instructions by software (e.g., floppy disks, CD-ROMs, EEPROMs, etc.), user interfaces for providing monitoring and manipulation possibilities to users (e.g., screens, keyboards, etc.), other interfaces or components for establishing links and / or connections under the control of processor units or parts (e.g., wired and wireless interface components, radio interface components including, for example, antenna units, components for forming radio communication parts, etc.), etc., wherein the corresponding components forming the interfaces (such as radio communication parts) may also be located at remote sites (e.g., radio heads or radio stations, etc.). It should be noted that in this specification, a processing part should not be regarded as representing only a physical part of one or more processors, but may also be regarded as a logical division of the indicated processing tasks performed by one or more processors. It should be understood that according to some examples, a so-called "liquid" or flexible network concept may be adopted, wherein the operations and functions of a network element, a network function, or another entity of the network may be performed in a flexible manner in different entities or functions, such as in a node, a host, or a server. In other words, the "division of labor" between the network elements, functions, or entities involved may vary from case to case.

[0104] According to Rel.16, the UE may be configured with a conditional handover (CHO) target cell configuration and at least one CHO execution condition in order to decide when to perform a handover to one or more prepared target cells. The (multiple) conditions are based on radio measurements of the serving cell and the target cell. In the CHO configuration, the (multiple) target cells may reserve a cell radio network temporary identifier (C-RNTI) and contention-free radio access (CFRA) resources for the UE. When the UE evaluates the CHO condition and the condition holds for a specific target cell, the UE applies the CHO configuration of the target cell and may use the reserved CFRA resources to initiate random access to the target cell. The UE may be configured with multiple conditions for multiple target cells.

[0105] Figure 1 An exemplary implementation of a CHO signaling diagram is schematically shown. CHO is designed so that the UE can autonomously perform handover without requiring the serving cell to trigger the handover execution after receiving a measurement report from the UE.

[0106] In step S101, the UE sends a measurement report that identifies 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 a target cell capable of supporting CHO should be prepared for the UE. The source RAN node sends a conditional handover request to multiple target RAN nodes. In each CHO request message, the source node indicates the cell(s) that should be prepared by the corresponding target node. The target RAN node performs admission control and sends a handover request ACK for the requested cell and the relevant conditional configuration for the cell as a response to the CHO request.

[0107] In step S109, the source RAN node sends an RRC reconfiguration message to the UE, which has a conditional configuration related to CHO. The UE receives the message and continues to exchange data with the source node. In steps S110 to S111, the UE evaluates the CHO conditions and performs conditional configuration for CHO where the conditions are met. In steps S111 to S114, the UE performs CHO to the selected target cell controlled by the target RAN node and stops TX / RX to / from the source node. In step S115, the target RAN node indicates to the source RAN node that the handover is successful. Finally, in step S116, user plane procedures such as data forwarding and path switching are completed afterwards.

[0108] In case of dual connectivity (DC), the target node (target master node MN) shall prepare multiple secondary cell groups (SCGs) (in the same or different secondary nodes SN) after receiving a conditional handover request from the source node (source MN). This means:

[0109] Option 1: The target RAN node sends multiple conditional configurations, each of which consists of a primary cell (PCell) and primary / secondary cell (PSCell) configurations, as a response to a single HO request.

[0110] Option 2: Alternatively, the target RAN node sends one conditional configuration for PCell and multiple conditional configurations for PSCell (which may be conditional PSCell change (CPC) or conditional PSCell addition (CPA)) as a response to a single HO request.

[0111] In both options, the target node sends multiple conditional configurations as a reply to a single CHO request.

[0112] Typically, the UE is limited to having a maximum number of (e.g., 8) conditional configurations in CHO. However, the target node is not aware of this limitation at a given point in time on the UE side, given the number of conditional configurations that already exist. For example, if the UE is already configured with 6 conditional configurations, and the target node offers 4 additional conditional configurations, the source node cannot offer these configurations to the UE and must make a choice that it has no right to make (the source node cannot tell which of the prepared PSCells are "more important", e.g., have better radio conditions). In addition, if the corresponding PSCell is not used, the target node reserves resources that the UE will no longer use.

[0113] Thus, in general, the present disclosure proposes techniques / mechanisms for limiting and controlling the number of conditional configurations that a target node can prepare through a CHO process.

[0114] To address at least some or all of the above problems, according to some example embodiments, the present disclosure generally proposes that a source node indicates to a target node how many conditional configurations should be delivered as a response to a conditional handover request.

[0115] Broadly speaking, this disclosure generally presents two different possible example approaches to controlling the number of conditional configurations that a target node prepares through a CHO process.

[0116] According to some possible (but non-limiting) implementations, the source MN triggers the addition of multiple candidate PSCells. For example, the source node indicates to the target node (possibly within a conditional handover request message): the maximum number of conditional configurations that the target node is allowed to prepare and provide in a handover request ACK message. The target node (MN) can use this information to decide how many target SNs it should contact to indicate to the corresponding target SN the number of PSCells that the target SN is to prepare. Therefore, the target node uses this information to decide the total number of conditional configurations to be included in the handover confirmation message. The advantage of this embodiment is that the identification of CHO preparation may be the same as in the case of classic CHO preparation: using UE ID and target PCell. However, in this case, if the CHO is canceled, all prepared PSCells are canceled because the PSCell configuration is included in a single CHO configuration. Therefore, if the PSCell is no longer valid, the CHO must be canceled and re-prepared, or if only one PSCell needs to be updated, the complete CHO must be updated.

[0117] According to some other possible (but non-limiting) implementations, multiple CHO configurations are requested sequentially, and a single PSCell configuration exists in one CHO configuration. For example, the target node indicates that it can provide multiple conditional configurations, but sends a single conditional configuration (within a traditional CHO handover request ACK) as a response to the conditional handover request. In order to retrieve more conditional configurations, the source node sends more handover requests for the same target PCell. If the source node decides to request more configurations, it will use a new indication (e.g., a flag) (e.g., called "CHO ​​increase") to indicate to the target node that the new CHO request for the same PCell should not release the existing preparation of the PCell. This indication is required so that the target node does not release the previous conditional configuration associated with the target PCell, as occurs in classic CHO. In these embodiments, each PSCell configuration is in a separate CHO configuration, and each CHO configuration has the same PCell configuration. Since the source node can send multiple new CHO requests associated with the same PCell, the (multiple) responses from the target node must be identified and matched with the request. Therefore, some additional identifier (e.g., CHO request ACK) for the response may be required. This embodiment effectively extends the identification of CHO preparation so that the PSCell is now part of it. This is different from the traditional behavior, but allows to enable, for example, CHO cancellation related to a specific PSCell in the future.

[0118] In an embodiment, the UE may inform the network of the number of conditional configurations for conditional switching that the UE can support. The UE may include this information in an existing message, or, for example, send a separate message to the source node.

[0119] Figure 2 Examples of signaling / messaging flow diagrams according to some example embodiments of the present disclosure are schematically illustrated.

[0120] Usually, in Figure 2 In the example embodiment, it will be appreciated that the source MN (e.g., gNB) is configured to make a decision regarding conditional switching.

[0121] In steps S201 and S202, the UE is configured with measurement configurations and reports measurements of neighboring PC cells and possible PS cells to the source MN. In step S203, the source MN determines whether CHO preparation of the UE is necessary or desired based on the measurements. At this point, the source MN may have received a message from the UE indicating the number of conditional configurations allowed for the UE or that the UE can support. The source MN may also obtain this information from other sources.

[0122] The source MN maintains a certain number of conditional configurations allowed for the UE in step S204, and determines how many additional conditional configurations can be allocated to the UE. To determine the number of additional conditional configurations, the source MN may consider the number of conditional PSCell change (CPC), conditional PSCell addition (CPA), conditional handover (CHO), and low layer mobility (LLM) configurations that have been configured for the UE. A conditional configuration is a PSCell / PCell configuration to be applied for a condition.

[0123] In step S205, the source MN sends a conditional handover request message to the target MN, and indicates the maximum number X of conditional configurations that the target MN is to provide for the UE. The conditional handover request message may include a measurement report received for the UE.

[0124] In the CHO request message, the source node may indicate a target primary cell of a primary cell group (PCell) that should be prepared by the corresponding target node.

[0125] The target node receives the CHO request message and may perform admission control on the received request.

[0126] In steps S206 and S207, based on measurements including measurements of candidate PSCells received from the source MN, the target MN determines a certain number of conditional configurations to be provided to the UE via a conditional switching request ACK. The number of conditional configurations determined by the target MN may be equal to or less than X indicated in step S205. The target MN determines to indicate a certain number of PSCells to be prepared by one or more target SNs through a corresponding SN add request. The SN add request may include a list of PSCell-1, PSCell-2, ..., PSCell-X to be prepared for the switching of the corresponding SN. The target SN prepares up to the indicated number of PSCells and sends an SN add request ACK message to the target MN (step S207). The target MN may send SN add requests to different target SNs. The target MN may collect responses from different target SNs.

[0127] The target MN prepares the conditional configurations received from the SN(s) and possibly the conditions for executing each target PSCell configuration, and sends it to the source MN together with the conditional handover request ACK (step S208).The target MN may explicitly indicate a certain number of conditional configurations to the source MN.

[0128] Each conditional configuration may be provided with a unique identifier ID. This ID is a unique identifier for distinguishing which CHO the same PCell refers to, since multiple CHOs may be prepared for the same PCell with different PSCells. Using UE ID and PCell ID is not sufficient, since the proposed CHO is used for the same UE and the same PCell, but is associated with a separate PSCell. If all PSCell configurations are in the same CHO configuration, the UE ID and PCell ID are sufficient to indicate a single CHO configuration.

[0129] In step S209, the source MN updates a certain number of conditional configurations currently configured with the UE: In one embodiment, the source MN uses a certain 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 configuration provided by the target MN to determine a certain number of conditional configurations.

[0130] In steps S210 to S217, the UE is configured with a conditional configuration (e.g., an RRC reconfiguration message). The UE receives the message, sends an acknowledgement message (e.g., RRC reconfiguration completed in step S211), continues to exchange data with the source node, and begins monitoring the condition for conditional switching. After the condition is satisfied (as determined in step S212), the UE then performs the same Figure 1 Similar PCell changes and PSCell additions / changes as described above (where Figure 2Step S213 in corresponds to Figure 1 Steps S112 and S113 in; Figure 2 S214 in corresponds to Figure 1 Steps S114 and S115 in Figure 1 compared to, Figure 2 Including PSCell access.

[0131] Figure 3 Another example of a signaling / message flow chart according to some exemplary embodiments of the present disclosure is schematically illustrated. This figure is a simplified flow chart that skips the interaction with the UE and does not show Figure 2 The redundant steps shown, in particular, change steps S205 and S209 of the previous embodiment (ie, the enhanced CHO preparation phase).

[0132] Again, the source MN may have acquired information about the number of conditional configurations allowed for the UE 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 allowed for the UE or that the UE can support.

[0133] In step S301, the source MN sends a conditional handover request to the target MN (compared with step S205). As mentioned above, the handover request may include measurement reports of neighboring PCells and possible PSCells, and an identifier of the PCell that the target MN should prepare.

[0134] In steps S302 to S303, the target MN sends (multiple) SN add requests to one or more target SNs, and each target SN sends an SN add request ACK message. In the case of multiple SNs involved, the target MN may determine to add configuration to the UE from only one PSCell. The SN add request and the SN add request ACK are each for a single PSCell and may indicate the required PSCell. In other words, the SN add request ACK may include the requested PSCell configuration.

[0135] The target SN determines the number of PSCells that can be added based on the measurements received from the target MN. To this end, the target MN can forward the measurement report to the target SN. Alternatively, other inputs such as OAM configuration can be used on the target SN side to determine the PSCells that can be added.

[0136] The target SN may indicate this to the target MN in the SN Add Request ACK message.Alternatively, the target MN may determine based on measurements received from the source MN that multiple target PSCells may be prepared for the same target PCell.

[0137] In step S304, the target MN determines based on the measurement or the (multiple) SN add request ACK message that multiple PSCells can be added for the same target PCell and these PSCells are potential target PSCells.

[0138] In step S305, the target MN sends a conditional handover request ACK to the source MN, which has a conditional configuration for the PSCell of the target SN and indicates to the source MN that it intends to (i.e., it can) send one or more additional conditional configurations for (multiple) other PSCells. The target MN indicates a unique identifier ID for each conditional configuration (compared with step S208).

[0139] In step S306, the source MN determines whether the UE can be assigned more conditional configurations. To this end, the source MN compares the maximum allowed number of conditional configurations with the actual number of conditional configurations configured on the UE. If it is determined that the UE can handle one or more additional conditional configurations, the process continues to step S307.

[0140] In step S307, the source MN sends a new conditional handover request to the target MN and adds an indication (or flag) "CHO ​​add" in the request so that the target MN keeps the previous conditional configuration and sends the new conditional configuration. The handover request may include a measurement report and an indication of the PCell.

[0141] In step S308, the target MN determines to retain (multiple) previous CHO preparations and sends another CHO conditional configuration to the source MN. The target MN determines to add another PSCell for CHO of the same PCell. The target MN sends an SN Add Request to the target SN and receives an SN Add Request ACK with the PSCell conditional configuration (steps S309 and S310). In step S311, the target MN sends a Conditional Handover Request ACK with an additional conditional configuration of the additional PSCell of the target SN to the source MN.

[0142] Typically, CHO configuration involves PCell and PSCell. PCell is the anchor point of CHO configuration. For example, in step S305, the CHO configuration of PCell1 and PSCell1 is provided with a first conditional handover request ACK. Then, in step S311, the CHO configuration of PCell1 and PSCell2 is provided with a second conditional handover request ACK. Therefore, in response to an additional CHO request marked with an indication (e.g., "CHO ​​increase") for maintaining the previous conditional configuration and sending a new conditional configuration, the target MN provides the conditional configuration of the same PCell but a different PSCell in the additional conditional handover request ACK.

[0143] The process may be repeated with step S306 to add additional conditional configurations by the source MN, possibly with different target MNs and / or different target SNs, until the required number of conditional configurations are collected. The process may then continue similarly to step S210 with configuration of the UE and the UE performing conditional handover (steps S212 to S217).

[0144] In summary, the present disclosure provides a technology / mechanism for limiting and controlling the number of conditional configurations that a target node can prepare through a CHO process. The present disclosure generally proposes that a source node indicates to a target node how many conditional configurations should be delivered as a response to a conditional handover request. Alternatively, a source node may send multiple conditional handover requests to a target node to retrieve the conditional configurations one by one.

[0145] Finally, it should be noted that although in the above-described example embodiments (with reference to the accompanying drawings), the messages passed / exchanged between network components / elements may appear to have specific / unambiguous names, depending on various implementations (e.g., underscore technology), these messages may have different names and / or be passed / exchanged in different forms / formats, as understood and appreciated by those skilled in the art.

[0146] According to some example embodiments, corresponding methods suitable for being performed by an apparatus (network element / component) as described above, such as a UE, a source MN, a target MN, a target SN, etc., are also provided.

[0147] It should also be noted that the above-mentioned device (equipment) features correspond to corresponding method features, but for reasons of simplicity, these method features may not be explicitly described. The disclosure of this document is considered to also extend to such method features. In particular, the present disclosure is understood to relate to methods of operating the above-mentioned devices and / or providing and / or arranging corresponding elements of these devices.

[0148] In addition, according to some other example embodiments, a corresponding device (for example, implementing the UE, source MN, target MN, target SN, etc. as described above) is also provided, which includes at least one processing circuit system and at least one memory for storing instructions executed by the processing circuit system, wherein the at least one memory and the instructions are configured to work together with the at least one processing circuit system to enable the corresponding device to at least perform the corresponding steps as described above.

[0149] However, in some other example embodiments, a corresponding apparatus (eg, implementing the UE, source MN, target MN, target SN, etc. as described above) is provided, the apparatus comprising corresponding components configured to at least perform the corresponding steps as described above.

[0150] It should be noted that the examples of the embodiments of the present disclosure are applicable to a variety of different network configurations. In other words, the examples shown in the above figures used as the basis for the above examples are merely illustrative and do not limit the present disclosure in any way. That is, based on the defined principles, other existing and proposed new functions available in the corresponding operating environment can be used in conjunction with the examples of the embodiments of the present disclosure.

[0151] It should also be noted that the disclosed example embodiments can be implemented in a variety of ways using hardware and / or software configurations. For example, the disclosed embodiments can be implemented using dedicated hardware and / or hardware associated with software that can be executed thereon. The components and / or elements in the accompanying drawings are merely examples and do not limit the scope of use or functionality of any hardware, software combined with hardware, firmware, embedded logic components, or a combination of two or more such components that implement a specific embodiment of the present disclosure.

[0152] It should be further noted that the description and the accompanying drawings illustrate only the principles of the present disclosure. Those skilled in the art will be able to implement various arrangements that, although not explicitly described or illustrated herein, embody the principles of the present disclosure and are included in its spirit and scope. In addition, all examples and embodiments outlined in the present disclosure are primarily for explanatory purposes only to help the reader understand the principles of the proposed method. In addition, all statements of the principles, aspects, and embodiments of the present disclosure and their specific examples provided herein are intended to cover their equivalents.

Claims

1. A first network node, configured to support establishing a connection to a user equipment UE via a radio access network, the first network node comprising: at least one processor; as well as at least one memory storing instructions, which, when executed by the at least one processor, cause the first network node to at least: determining preparation for a conditional handover of the UE to a second network node based on measurements performed by the UE; sending a conditional handover request for the UE to the second network node, wherein the conditional handover request includes an indication related to: a number of conditional configurations prepared by the second network node for the handover permission; as well as A conditional handover request confirmation is received from the second network node, the conditional handover request confirmation comprising at least one condition configuration related to at least one target cell for the handover.

2. The first network node according to claim 1, wherein the network node is configured to: A certain number of conditional configurations allocated to the UE is maintained, and the number is updated after receiving the conditional handover request confirmation.

3. The first network node according to claim 1 or 2, wherein the network node is configured to: A maximum number of conditional configurations allocatable to and / or supported by the UE is determined.

4. The first network node according to claim 3, wherein the network node is configured to: sending a conditional handover request for the UE to a third network node, wherein the conditional handover request comprises an indication related to the number of conditional configurations prepared by the third network node for the handover permission, wherein the number is coordinated with the number sent to the second node and the maximum number supported by the user equipment.

5. A first network node according to any preceding claim, wherein the network node is configured to: A message is sent to the UE, the message comprising an indication related to: the received at least one conditional configuration related to the at least one target cell of the second network node.

6. The first network node according to any preceding claim, wherein the conditional handover request confirmation comprises: The conditional switching request confirmation includes a certain number of the at least one condition configuration.

7. A first network node, configured to support establishment of a connection to a user equipment UE via a radio access network, the first network node comprising: at least one processor; as well as at least one memory storing instructions, which, when executed by the at least one processor, cause the first network node to at least: determining preparation for a conditional handover of the UE to a second network node based on measurements performed by the UE; sending a conditional handover request for the UE to the second network node; and A conditional handover request acknowledgement is received from the second network node, the conditional handover request acknowledgement comprising an indication that at least one additional conditional configuration related to one or more further target cells is applicable for the handover.

8. The first network node according to claim 7, wherein the first network node is configured to: determining whether the UE can be allocated at least one more conditional configuration and, in this case, sending a further conditional handover request to the second network node to obtain another conditional configuration related to a further target cell.

9. The first network node according to claim 8, wherein the further conditional handover request comprises an indication that the second network node should not release the existing preparation for the target cell and return another conditional configuration related to the further target cell in a further conditional handover request confirmation.

10. The first network node according to claim 9, wherein the conditional handover request confirmation comprises: Conditions for a primary cell in a primary cell group and a primary cell in a secondary cell group are configured, and the another conditional handover request confirmation includes: condition configuration for another primary cell in the secondary cell group.

11. The first network node according to claim 9, wherein the conditional handover request confirmation comprises: Conditions are configured for a primary cell in a primary cell group and a primary cell in a secondary cell group, and the another conditional handover request confirmation includes: condition configurations for another primary cell in the secondary cell group and the same primary cell in the primary cell group.

12. The first network node according to any one of claims 8 to 11, wherein the first network node is configured to: aggregating conditional configurations received with different conditional handover request confirmations for the same UE, and A message is sent to the UE, the message comprising an indication related to: the collected at least one conditional configuration related to the at least one target cell of the second network node.

13. The first network node according to any one of the preceding claims, wherein the conditional handover request confirmation comprises: A unique identifier associated with a conditional configuration included in the conditional handover request acknowledgment.

14. The first network node according to any one of the preceding claims, wherein the conditional handover request comprises: preparing a request for conditional handover to the second network node and the secondary node, wherein the first network node is further configured to: A conditional handover request confirmation is received from the second network node, the conditional handover request confirmation comprising the at least one conditional configuration related to at least one target cell of the second network node and at least one secondary cell of the secondary node.

15. The first network node according to claim 14, wherein the first network node is a source primary node for a dual connection of the UE in the radio access network, the second network node is a target primary node for the dual connection of the UE, the conditional handover request comprises an indication of a primary cell PCell associated with the second network node, and the conditional handover request confirmation comprises one or more indications of a secondary cell PSCell associated with the secondary node.

16. The first network node according to any one of the preceding claims, wherein the first network node is configured to: An indication of a number of conditional configurations for conditional switching that the UE can support is received from the UE.

17. A second network node, configured to support establishment of a connection to a user equipment UE via a radio access network, the second network node comprising: at least one processor; as well as at least one memory storing instructions, which, when executed by the at least one processor, cause the second network node to at least: receiving, from the first network node, a conditional handover request for the UE, the conditional handover request comprising an indication related to: a number of conditional configurations prepared by the second network node for the handover permission; determining, based on the received conditional handover request, a plurality of target cells to be prepared to be controlled by the second network node for the handover; as well as A conditional handover request confirmation is sent to the first network node, the conditional handover request confirmation comprising: at least one condition configuration related to at least one target cell for the handover.

18. The second network node according to claim 17, wherein the received conditional handover request comprises information about radio measurements performed by the UE on a target cell, and the second network node is configured to: Based on the radio measurements and the number of conditional configurations prepared by the second network node for the handover allowance, a number of target cells potentially available for the conditional handover request and the number of corresponding conditional configurations are determined.

19. The second network node according to claim 17, wherein the second network node is configured to: sending a request to the secondary node for preparing a plurality of target cells for the handover; and A confirmation is received from the secondary node, the confirmation including a conditional configuration for the prepared target cell.

20. The second network node according to claim 19, wherein the second network node is a target primary node for dual connectivity of the UE in the radio access network, the request for preparing multiple target cells is a secondary node SN addition request, and the conditional switching request includes an indication of a primary cell PCell associated with the second network node, and the conditional switching request confirmation includes one or more indications of a secondary cell PSCell associated with the secondary node.

21. A second network node, configured to support establishment of a connection to a user equipment UE via a radio access network, the second network node comprising: at least one processor; as well as at least one memory storing instructions, which, when executed by the at least one processor, cause the second network node to at least: receiving, from a first network node, a conditional handover request for the UE, the conditional handover request comprising information about radio measurements performed by the UE on a target cell; determining a plurality of target cells to be prepared for the handover to be controlled by the second network node; and A conditional handover request acknowledgement is sent to the first network node, the conditional handover request acknowledgement comprising an indication that at least one additional conditional configuration for one or more further target cells is applicable for the handover.

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

23. The second network node according to claim 21, wherein the second network node is configured to: Sending a request for preparing a target cell for the handover to the secondary node, wherein the request for preparing the target cell includes: at least a portion of the received information regarding radio measurements for the target cell; as well as A confirmation is received from the secondary node, the confirmation including a conditional configuration for the prepared target cell, the confirmation including an indication that a plurality of target cells controlled by the secondary node are potentially available for the handover.

24. The second network node according to any one of claims 21 to 23, wherein the second network node is configured to: A further conditional handover request is received from the first network node, the further conditional handover request comprising an indication that the second network node should not release an existing preparation for a target cell and returning another conditional configuration of a further target cell in a further conditional handover request acknowledgment.

25. The second network node according to claim 24, wherein the second network node is configured to: Determining to add an additional target cell for the handover by: sending another request to the secondary node for preparing the additional target cell for the handover, and receiving another confirmation from the secondary node, the another confirmation including a conditional configuration for the prepared additional target cell; and Another conditional handover request confirmation is sent to the first network node, the another conditional handover request confirmation comprising the conditional configuration of the further target cell.

26. The second network node according to any one of claims 21 to 25, wherein the conditional handover request confirmation comprises: A unique identifier associated with a conditional configuration included in the conditional handover request acknowledgment.

27. A second network node according to claim 23, wherein the second network node is a target primary node for dual connectivity of the UE in the wireless access network, the request for preparing a target cell is a secondary node SN addition request, and the conditional switching request includes an indication of a primary cell PCell associated with the second network node, and the conditional switching request confirmation includes one or more indications of a secondary cell PSCell associated with the secondary node.

28. A user equipment UE, configured to operate in a radio access network, the UE comprising: at least one processor; as well as at least one memory storing instructions, which, 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 switching that the UE can support; sending measurements for a target cell for potential handover to a network node; as well as A message for conditional handover is received from the network node, the message comprising an indication related to at least one conditional configuration related to at least one of the target cells.

29. The user equipment according to claim 28, configured to: The at least one conditional configuration is evaluated, and if at least one condition is met, a handover is performed to the target cell associated with the condition being met.

30. A system comprising: The first network node according to any one of claims 1 to 16; as well as A User Equipment UE according to claim 28 or 29 served by a cell of the first network node.

31. A method of a first network node, the first network node being configured to support establishing a connection to a user equipment UE via a radio access network, the method comprising: determining preparation for a conditional handover of the UE to a second network node based on measurements performed by the UE; sending a conditional handover request for the UE to the second network node, wherein the conditional handover request includes an indication related to: a number of conditional configurations prepared by the second network node for the handover permission; as well as A conditional handover request confirmation is received from the second network node, the conditional handover request confirmation comprising at least one condition configuration related to at least one target cell for the handover.

32. A method of a first network node, the first network node being configured to support establishing a connection to a user equipment UE via a radio access network, the method comprising: determining preparation for a conditional handover of the UE to a second network node based on measurements performed by the UE; sending a conditional handover request for the UE to the second network node; and A conditional handover request acknowledgement is received from the second network node, the conditional handover request acknowledgement comprising an indication that at least one additional conditional configuration related to one or more further target cells is applicable for the handover.

33. A method of a second network node, the second network node being configured to support establishing a connection to a user equipment UE via a radio access network, the method comprising: receiving, from the first network node, a conditional handover request for the UE, the conditional handover request comprising an indication related to: a number of conditional configurations prepared by the second network node for the handover permission; determining, based on the received conditional handover request, a plurality of target cells to be prepared to be controlled by the second network node for the handover; as well as A conditional handover request confirmation is sent to the first network node, the conditional handover request confirmation comprising: at least one condition configuration related to at least one target cell for the handover.

34. A method of a second network node, the second network node being configured to support establishing a connection to a user equipment UE via a radio access network, the method comprising: receiving, from a first network node, a conditional handover request for the UE, the conditional handover request comprising information about radio measurements performed by the UE on a target cell; determining a plurality of target cells to be prepared for the handover to be controlled by the second network node; and A conditional handover request acknowledgement is sent to the first network node, the conditional handover request acknowledgement comprising an indication that at least one additional conditional configuration for one or more further target cells is applicable for the handover.

35. A method for a user equipment (UE), the UE being configured to operate in a radio access network, the method comprising: Indicating to the network: the number of conditional configurations for conditional switching that the UE can support; sending measurements for a target cell for potential handover to a network node; as well as A message for conditional handover is received from the network node, the message comprising an indication related to at least one conditional configuration related to at least one of the target cells.

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

37. A memory storing computer-readable instructions for causing an apparatus to execute the method according to any one of claims 31 to 35.

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