Conditional switching enhancement

Abstract

Methods, apparatuses, and computer program products provided herein improve conditional switching (CHO) techniques to handle continuous network connections when a user equipment (UE) moves between network cells. The disclosed techniques may be utilized in scenarios where paths of user equipment (UE) between various network nodes are known, such as in high speed train cases. According to the disclosed method, a source network node triggers CHO preparation to a plurality of target network nodes. The last prepared network node receives an indication to trigger a further CHO preparation to an additional target network node. Since the path of the UE is the UE and / or known in the network, the UE evaluates only the CHO condition of the next target network node in the path. Accordingly, according to the disclosed method, CHO technology may be enhanced by improving the efficiency of CHO.

Description

Technical Field

[0001] Example embodiments relate generally to wireless communications and, more particularly, but not exclusively, to improvements and enhancements to conditional handover (CHO). Background Art

[0002] Conditional Handover (CHO) is a mobility enhancement defined in 3rd Generation Partnership Project (3GPP) Release 16 (Rel-16) that aims to reduce radio link failures and handover failures, particularly those caused by user equipment (UE) moving between cells in the network. CHO is similar to the baseline handover procedure of New Radio (NR) Release 15 (Rel-15).

[0003] In CHO, instead of preparing one target cell in the baseline handover scenario, multiple candidate target cells are prepared in advance in the network, which enables the handover command to be sent to the UE earlier than in the baseline handover, and when the radio signal is still strong, rather than when the connection becomes challenging as in the baseline handover case. When the command is received, the UE stores the command instead of applying it immediately. When one of the configured candidate target cells meets the conditions configured in the UE (such as conditions related to signal strength measurement), the UE performs the handover according to the stored command, and then the UE performs the handover and connects to the target node. Summary of the invention

[0004] Figure 1 An example message sequence chart for CHO is shown in . The first operations 1-9 are similar to the baseline handover of NR Rel-15 [Technical Specification (TS) 38.300]. In operation 1, the configured measurement event triggers the UE 100 to send a measurement report. Based on the report, the source node 102 (e.g., gNB) can prepare one or more target nodes 104 or target cells for handover (CHO request as shown in operation 3) and CHO request confirmation as shown in operation 7 (and operation 8), and then send an RRC reconfiguration (including CHO conditions) to the UE as shown in operation 9. Operations 5 and 6 include admission control at the target node 104 and / or other potential target nodes 104.

[0005] In operation 10, the UE 100 evaluates a CHO condition, and in operation 11, if the target cell satisfies the CHO condition, data transmission to and / or from the source cell may be stopped. Operation 12 includes transmission of a physical random access channel (PRACH) preamble, and operation 13 includes reception of a random access channel (RACH) response. Operation 14 includes transmission of an indication of radio resource control (RRC) reconfiguration completion. Operation 15 includes an indication of a successful handover from the target node 104 to the source node 102, and operation 16 includes stopping data transmission between the UE 100 and the source node 102. In operation 17, a sequence number (SN) state transfer between the source node 102 and the target node 104 is indicated. In operation 18, data forwarding from the source node 102 to the target node 104 occurs. Operation 19 includes releasing the CHO preparation from the source node 102 to the target node 104, and at operation 20, a path switch occurs, and corresponding updates to the user plane function (UPF 108) and the access and mobility management function (AMF) 110.

[0006] For baseline handover in NR Rel-15, the UE will immediately access the target cell to complete the handover. In contrast, for CHO, the UE will only access the target cell if additional CHO execution conditions are met (e.g., the handover preparation and execution phases are decoupled). This condition is determined by the source node at Figure 1 9 in RRC reconfiguration. For intra-frequency handover, at least event A3 defined in TS38.331 can be configured as a CHO execution condition, where the UE triggers CHO execution when the measurement of the target cell is better than the measurement of the serving cell for some trigger time (TTT) by some offset. For inter-frequency handover, event A5 is configured, where the UE triggers CHO execution when the measurement of the serving cell is below threshold 1 and the measurement of the target cell is above threshold 2 of TTT.

[0007] In CHO, the UE can prepare up to 8 candidate target cell configurations. In addition, data forwarding from the source cell to the target cell can be of two types, including delayed data forwarding and early data forwarding.

[0008] According to delayed date forwarding, the source node triggers data forwarding to the target node after receiving a handover success message from the target node (as shown in operations 15-18). This configuration is called delayed data forwarding because it occurs after the UE performs random access to the target cell. Delayed data forwarding may cause some interruption to the UE because the target node cannot serve the UE immediately after the UE completes the handover execution.

[0009] According to early data forwarding, after the source node sends the configuration of the candidate target cell in operation 9, it may trigger data forwarding to one or more candidate target nodes.

[0010] Since the source node does not know in advance which target node the UE will perform random access to, it is necessary to perform data forwarding to multiple candidate target nodes. This will reduce the interruption caused by delayed data forwarding, but will increase the signaling overhead on the Xn interface.

[0011] When UEs are mobile, sometimes at high and / or ultra-high speeds, the need for continuous connectivity increases, creating challenges for networks including configurations utilizing CHO. “Hyperloop” is a high-speed transportation system for people and cargo based on vacuum tube trains. Maglev trains are deployed in partially evacuated tubes or tunnels where reduced air drag allows travel at very high (hypersonic) speeds with relatively little power.

[0012] While there are multiple options in terms of technical design, a Hyperloop system generally consists of three components: a tube, a pod, and a terminal. The tube is a large, sealed, low-pressure system (usually a long tunnel). The pod is a coach pressurized at atmospheric pressure that uses aerodynamic or magnetic propulsion with essentially no air resistance or friction inside the tube. The terminal handles the arrival and departure of the pod while maintaining low air pressure.

[0013] Fifth generation (5G) New Radio (NR) networks can be used to provide high-performance connectivity in high-speed scenarios such as Hyperloop. For example, BOOST provides train-to-ground communications, as does the high-speed train work item in 3GPP RAN WG3.

[0014] In a hyperloop, the trains travel at extremely high speeds, such as 1000 km / h, or even faster, which makes reliable handover of UEs from one cell to another difficult, as the cell coverage area may be relatively small. For example, terminals may be hundreds of meters away from other terminals to ensure a high signal-to-noise ratio (S / NR) for high-capacity links. For example, the proximity of the cells can provide high-resolution real-time video streaming from a remote cockpit client). Existing techniques such as conventional handover (the baseline handover mechanism of NR Rel-15) are ineffective, as the UE may miss receiving the handover command from the network on time, given the very high speed of the trains.

[0015] Furthermore, it would be beneficial if the UE installed on the high-speed train or the accompanying user inside the train had candidate target cell configurations in advance so that the UE could apply them when needed. Regarding CHO implementation, starting from Rel-18, the UE is able to receive multiple CHO configurations from the source node, which can be applied (and remain valid) after performing a handover. For example, in Figure 2In the example, the UE may receive CHO configurations of cells 2, 3, 4, and 5 from serving cell 1, where the UE may use the CHO configuration of cell 2 to perform a handover from cell 1 to cell 2, use the CHO configuration of cell 3 to perform a handover from cell 2 to cell 3, and so on.

[0016] Certain embodiments disclosed herein provide an efficient solution for such high-speed mobility scenarios by introducing enhancements to CHO.At least some of the problems solved according to certain embodiments are described below.

[0017] One challenge addressed in accordance with certain embodiments includes improving session continuity by making user plane packets available in a target node without interruption upon cell change. This can be achieved by using early data forwarding. This can be achieved given that the path of the hyperloop train is predetermined and the next candidate target cell is known in advance, however, forwarding user plane packets to multiple target cells results in high and unnecessary signaling overhead on the network (e.g., Xn interface).

[0018] Another challenge includes that, given that the UE is pre-configured with N1 CHO configurations for the upcoming N1 target cells by, for example, serving cell X_1, then the last prepared target cell X_N1 (from the N1 cells) needs to reconfigure the UE for the next upcoming N2 candidate target cells. Note that N2 may be different from N1, since cells X_1 and X_N1 may have different numbers of neighboring cells connected to the Xn interface. The problem is that the last serving cell (e.g., target cell X_N1) may not know that it needs to re-trigger CHO preparation for the next upcoming N2 candidate target cells.

[0019] In CHO Rel.16, after receiving the candidate target cell configuration, the UE starts to evaluate all CHO conditions associated with the candidate target cell configuration (such as Figure 1 This is necessary because the UE does not know the target cell to which it will perform a handover. However, in the hyperloop train scenario, the next target cell is known in advance, so it would be inefficient to start evaluating the CHO conditions of candidate target cells that the UE will later visit after performing a handover to a different target cell.

[0020] Certain embodiments disclosed herein exploit the observation that, in any train scenario, the train path or trajectory is known or can be determined within the network. The path information can be obtained explicitly from the track operator (e.g., by pre-configuring a railway track plan or by adaptively monitoring the operation of the linear motors that accelerate the maglev train) or implicitly from the network, such as the 5G NR network itself (e.g., using a local location management function (LMF) that allows the train to be located in real time using integrated 5G NR capabilities). In this context, at least some of the disclosed embodiments include at least two techniques, depending on whether the UE knows the UE's path information, or the UE does not necessarily know it (but it is known in the network).

[0021] In the case where the path information is known in the network or can be determined in the network, certain embodiments of the first technology are enabled at least by a standard core-based positioning server (such as LMF). The first technology includes at least aspects #1-5 described below, which are numbered for reference purposes only and are not intended to limit the scope of the present disclosure. In the second technology, the positioning information can be based on, for example, a 5G NR UE, which knows its precise location through the LMF using the standardized LTE Positioning Protocol (LPP). The second technology includes at least aspects #5-8 described below, which are numbered for reference purposes only and are not intended to limit the scope of the present disclosure.

[0022] In the first technology, when the path information of the UE is known or can be determined in the network, but the UE does not necessarily know it, at least the following aspect #1 is performed. Based on the cell list X along the path that the UE will visit, at least the serving cell (e.g., Figure 2 The processing circuit system of cell 1) in triggers active conditional handover preparation of candidate target cells (e.g., cells 2, 3, and 4) whose gNBs have an Xn interface with the serving (source) gNB or network node.

[0023] In addition, in the first technique, during conditional handover preparation, at least the following aspect #2 is implemented. At least the processing circuitry and / or the communication interface of the source gNB (controlling the serving cell 1) indicates to another target gNB 2 (controlling the next target cell 2) a cell identifier, such as a cell identifier (e.g., PCI) of a target cell (e.g., target cell 3) for which it should perform early data forwarding. Thus, aspect #2 addresses the high and unnecessary signaling overhead described above regarding early data forwarding to multiple cells, and instead initiates early data forwarding to a defined number of cells based on the UE's path.

[0024] In addition, in the first technology, during the handover preparation, at least the following aspect #3 is performed. According to aspect #3, at least the processing circuit system and / or the communication interface of the source gNB (controlling the serving cell 1) indicates to another target gNB 3 (controlling the second next target cell 3) the cell identifier (e.g., PCI) of the target cell (e.g., target cell 4) for which it should perform early data forwarding and the cell identifier (e.g., PCI) of the source cell (e.g., target cell 2) of the handover. The latter cell identifier is used because the target gNB 3 (controlling the target cell 3) needs to know to which serving cell it should send the "handover success" message ( Figure 1 Operation 15 in ). The indication of the physical cell provided according to certain embodiments disclosed herein solves the above-mentioned high and unnecessary signaling overhead regarding early data forwarding to multiple cells.

[0025] In addition, in the first technology, during handover preparation, at least the following aspect #4 is provided. At least the processing circuit system and / or the communication interface of the source gNB (controlling the serving cell 1) indicates to another target gNB 4 (controlling the last target cell 4) the cell identifier (e.g., PCI) of the source cell (e.g., target cell 3) of the handover, a flag that triggers new CHO preparation to other target cells, and a list X of cells that the UE will visit. This aspect #4 allows the disclosed preparation process to be repeated iteratively. It should be noted that the flag and list X are required because the target gNB 4 prepares the next upcoming N2 candidate target cells for the UE whose gNB has an Xn interface with the target gNB4. Providing a flag to trigger new CHO preparation according to certain embodiments solves the above-mentioned challenges regarding the last cell serving cell, for example, the target cell X_N1 may not know that it needs to re-trigger CHO preparation for the next upcoming N2 candidate target cells.

[0026] In addition, in the first technology, at least the following aspect #5 is implemented. In aspect #5, when providing CHO configuration for candidate target cells, the network (such as via at least the processing circuit system and communication interface of serving cell 1) indicates to the UE the order in which it should evaluate CHO execution conditions. For example, the serving cell may indicate that when the UE is served by (serving) cell 1, the CHO execution conditions of target cell 2 should be evaluated, when the UE is served by cell 2, the CHO execution conditions of target cell 3 should be evaluated, and so on. This indication for evaluating CHO execution conditions can reduce or eliminate inefficiencies that may otherwise occur when the evaluation of CHO conditions of candidate target cells to be visited by the UE immediately begins after performing a handover to a different target cell.

[0027] When the path information is known in the UE, the second technique provided herein is performed. According to the second technique of certain embodiments disclosed herein, at least aspect #6 is performed, including the UE notifying the serving cell 1 of the next candidate target cell based on the cell list X in the path along which the UE will visit. After receiving this information, the source cell together with at least the processing circuit system and the communication interface can trigger the preparation of the candidate target cells 2, 3, 4, similar to the above aspects #2-4 of the first method. Note that in aspect #4, when performed by the second technique, the source gNB may not need to include the flag and the cell list X, because it can now be notified by the UE as shown in aspect #7 described below.

[0028] The second technique according to certain example embodiments also includes at least aspect #7, including the UE, together with at least the processing circuit system and the communication interface, notifying the last serving cell 4 of the next candidate target cell that should be prepared based on the cell list X in the path along which the UE will visit and the CHO configuration list received from the serving cell 1. As provided according to certain embodiments, the UE sending an indication to the last serving cell can solve the above-mentioned challenges regarding the last serving cell, for example, the target cell X_N1 may not know that it needs to re-trigger CHO preparation for the next upcoming N2 candidate target cells.

[0029] The second technique according to certain example embodiments also includes at least aspect #8, including the UE, together with at least the processing circuit system and the communication interface, determining the CHO execution conditions that need to be evaluated based on the PCI of the serving cell based on the cell list X in the path along which the UE will visit and the CHO configuration list received from the serving cell 1. For example, when the UE is served by (serving) cell 1, the UE evaluates the CHO execution conditions of target cell 2, when the UE is served by cell 2, the CHO execution conditions of target cell 3 should be evaluated, and so on. The UE's determination of the CHO execution conditions to be evaluated reduces or eliminates inefficiencies that may otherwise occur if the evaluation of the CHO conditions of the candidate target cells that the UE will visit later after performing a handover to a different target cell is immediately started.

[0030] An apparatus is provided, the apparatus comprising at least one processor and at least one memory storing instructions, the instructions, when executed by the at least one processor, causing the apparatus to at least trigger conditional handover (CHO) preparation to a plurality of target network nodes in a path along which a user equipment (UE) is determined to move, wherein the CHO preparation comprises causing transmission of a cell identifier of a next target network node of a recipient target network node to the respective recipient target network node, and causing transmission of a cell identifier of a previous network node of the recipient target network node to the respective recipient target network node if the previous network node of the recipient target node is not the apparatus.

[0031] The instructions, when executed by the at least one processor, further cause the apparatus to cause at least transmission of an indicator for triggering additional CHO preparations to other target network nodes and a list of cell identifiers of respective other target network nodes to a last network node triggered by the apparatus for CHO preparation.

[0032] According to certain embodiments, the path along which the UE is determined to move includes a path from the apparatus configured as the first network node to the second network node, to the third network node, and to the fourth network node, wherein the CHO preparation further comprises causing transmission of a cell identifier of the third network node to the second network node, and causing transmission of a cell identifier of the fourth network node and a cell identifier of the second network node to the third network node. An indicator and a list of cell identifiers for triggering additional CHO preparation are sent from the apparatus to the fourth network node.

[0033] The instructions, when executed by the at least one processor, further cause the apparatus to at least cause transmission of an indication of a sequence of CHO conditions to be evaluated to the UE, wherein respective CHO conditions are associated with respective network nodes in a path within which the UE is determined to be moving.

[0034] Another apparatus is provided that includes at least one processor and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus to at least receive a cell identifier of a next target network node from a source network node and perform early data forwarding to the next target network node.

[0035] The instructions, when executed by the at least one processor, further cause the apparatus to receive at least from a source network node an indication for triggering conditional handover (CHO) preparations to a plurality of target network nodes, and in response, trigger CHO preparations to a plurality of target network nodes, the plurality of target network nodes being indicated by the source network node.

[0036] The instructions, when executed by the at least one processor, further cause the apparatus to receive at least a cell identifier of a previous network node from the source network node and, in response, cause transmission of a handover success message to the previous network node based on the cell identifier.

[0037] Another apparatus is provided, the apparatus comprising at least one processor and at least one memory storing instructions, the instructions, when executed by the at least one processor, causing the apparatus to at least receive an indication of a sequence of conditional handover (CHO) conditions to be evaluated, wherein respective CHO conditions are associated with respective network nodes, the respective network nodes being in a path along which the apparatus is determined to move, and determining the conditional handover (CHO) condition to be evaluated for a next network node toward which the apparatus moves based on a cell identifier of a source network node and path information of the apparatus. The path information of the apparatus is received from a network entity and includes respective cell identifiers of the network nodes toward which the apparatus moves.

[0038] An apparatus is provided, the apparatus comprising at least one processor and at least one memory storing instructions, the instructions, when executed by the at least one processor, causing the apparatus to at least cause transmission of an indicator for triggering CHO preparation for a target network node and a list of cell identifiers of the respective target network nodes to a source network node, the target network node receiving from the source network node an indication of a conditional handover (CHO) condition to be evaluated in a path along which the apparatus moves, wherein the respective CHO condition is associated with the respective one of the target network nodes according to the path, and evaluating the respective CHO condition of a next network node towards which the apparatus moves.

[0039] The instructions, when executed by the at least one processor, further cause the apparatus to cause at least transmission of an indicator for triggering additional CHO preparations to other target network nodes and a list of cell identifiers of respective other target network nodes to a last network node indicated by the source network node for CHO preparation.

[0040] Another apparatus is provided, the apparatus comprising at least one processor and at least one memory storing instructions, the instructions, when executed by the at least one processor, causing the apparatus to receive at least an indication from a user equipment (UE) served by the apparatus in a network, the indication being used to trigger conditional handover (CHO) preparation with a plurality of target network nodes, the plurality of target network nodes being in a path in which the UE moves, and triggering the CHO preparation with the plurality of target network nodes by causing transmission of a cell identifier of a next target network node of the respective recipient target network node and a cell identifier of a previous network node of the respective recipient target network node to the respective recipient target network node.

[0041] A method is provided, the method comprising triggering conditional handover (CHO) preparation to a plurality of target network nodes in a path along which a user equipment (UE) is determined to move, wherein the CHO preparation comprises causing transmission of a cell identifier of a next target network node of a recipient target network node to the respective recipient target network node, and if a previous network node of the recipient target node is not a source network node of the cell identifier of the next target node, causing transmission of a cell identifier of a previous network node of the recipient target network node to the respective recipient target network node.

[0042] The method further comprises causing transmission of an indicator for triggering additional CHO preparations towards other target network nodes and a list of cell identifiers of respective other target network nodes to the last network node triggered by the source network node for CHO preparation.

[0043] In certain embodiments, the path along which the UE is determined to move includes a path from a source network node configured as the first network node to a second network node, to a third network node, and to a fourth network node, wherein the CHO preparation further comprises causing transmission of a cell identifier of the third network node to the second network node, and causing transmission of a cell identifier of the fourth network node and a cell identifier of the second network node to the third network node. An indicator and a list of cell identifiers for triggering additional CHO preparation are sent from the source network node to the fourth network node.

[0044] The method comprises causing transmission to the UE of an indication of a sequence of CHO conditions to be evaluated, wherein respective CHO conditions are associated with respective network nodes in a path in which the UE is determined to be moving.

[0045] Another method is provided, the method comprising receiving a cell identifier of a next target network node from a source network node, and performing early data forwarding to the next target network node. The method also comprises receiving an indication from the source network node for triggering conditional handover (CHO) preparation to a plurality of target network nodes, and in response triggering CHO preparation to a plurality of target network nodes, the plurality of target network nodes being indicated by the source network node. The method also comprises receiving a cell identifier of a previous network node from the source network node, and in response causing transmission of a handover success message to the previous network node based on the cell identifier.

[0046] Another method is provided, the method comprising receiving an indication of a sequence of conditional handover (CHO) conditions to be evaluated, wherein the respective CHO conditions are associated with respective network nodes that are in a path along which the device is determined to move, and determining the conditional handover (CHO) condition to be evaluated for a next network node toward which the UE moves based on a cell identifier of a source network node and path information of the UE. The path information of the UE is received from a network entity and includes respective cell identifiers of the network nodes toward which the UE moves.

[0047] Another method is provided, the method comprising causing transmission of an indicator for triggering CHO preparation for a target network node and a list of cell identifiers of respective target network nodes to a source network node, the target network node receiving from the source network node an indication of a conditional handover (CHO) condition to be evaluated in a path along which the UE moves, wherein the respective CHO condition is associated with respective ones of the target network nodes according to the path, and evaluating the respective CHO condition of the next network node towards which the UE moves. The method further comprises causing transmission of an indicator for triggering additional CHO preparations to other target network nodes and a list of cell identifiers of respective other target network nodes to a last network node indicated by the source network node for CHO preparation.

[0048] Another method is provided, the method comprising receiving an indication from a user equipment (UE) served by a source network node in a network, the indication for triggering conditional handover (CHO) preparation with a plurality of target network nodes, the plurality of target network nodes being in a path in which the UE is moving, and triggering the CHO preparation with the plurality of target network nodes by causing transmission of a cell identifier of a next target network node of the respective recipient target network nodes and a cell identifier of a previous network node of the recipient target network node to the recipient target network node.

[0049] An apparatus is provided, the apparatus comprising means for triggering conditional handover (CHO) preparation to a plurality of target network nodes in a path along which a user equipment (UE) is determined to move, wherein the means for CHO preparation comprises means for causing transmission of a cell identifier of a next target network node of a corresponding recipient target network node to the recipient target network node, and causing transmission of a cell identifier of a previous network node of the recipient target network node to the corresponding recipient target network node if the previous network node of the recipient target node is not the apparatus.

[0050] The apparatus further includes means for causing transmission of an indicator for triggering additional CHO preparations to other target network nodes and a list of cell identifiers of respective other target network nodes to a last network node triggered by the apparatus for CHO preparation.

[0051] According to certain embodiments, the path along which the UE is determined to be moving includes a path from the apparatus configured as the first network node to the second network node, to the third network node, and to the fourth network node, wherein the CHO preparation further includes causing transmission of a cell identifier of the third network node to the second network node, and causing transmission of a cell identifier of the fourth network node and a cell identifier of the second network node to the third network node.

[0052] An indicator and a list of cell identifiers for triggering additional CHO preparation are sent from the apparatus to a fourth network node. The apparatus also includes means for causing transmission to the UE of an indication of a sequence of CHO conditions to be evaluated, wherein the respective CHO conditions are associated with respective network nodes in a path in which the UE is determined to be moving.

[0053] Another apparatus is provided, the apparatus including means for receiving a cell identifier of a next target network node from a source network node, and means for performing early data forwarding to the next target network node. The apparatus also includes means for receiving an indication from the source network node for triggering conditional handover (CHO) preparation to a plurality of target network nodes, and in response, triggering CHO preparation to the plurality of target network nodes, the plurality of target network nodes being indicated by the source network node.

[0054] The apparatus also includes means for receiving a cell identifier of a previous network node from the source network node, and means for causing, in response, transmission of a handover success message to the previous network node based on the cell identifier.

[0055] The device also includes means for receiving an indication of a sequence of conditional handover (CHO) conditions to be evaluated, wherein the respective CHO conditions are associated with respective network nodes that are in a path along which the device is determined to move; and means for determining a conditional handover (CHO) condition to be evaluated for a next network node toward which the device moves based on a cell identifier of a source network node and path information of the device. The path information of the device is received from a network entity and includes respective cell identifiers of the network nodes toward which the device moves.

[0056] An apparatus is provided, the apparatus comprising means for causing transmission of an indicator for triggering CHO preparation for a target network node and a list of cell identifiers of the respective target network nodes to a source network node, the target network node being in a path along which the apparatus moves; means for receiving an indication of a conditional handover (CHO) condition to be evaluated from the source network node, wherein the respective CHO condition is associated with a respective one of the target network nodes according to the path; and means for evaluating the respective CHO condition of a next network node towards which the apparatus moves.

[0057] The apparatus also includes means for causing transmission of an indicator for triggering additional CHO preparations to other target network nodes and a list of cell identifiers of respective other target network nodes to a last network node indicated by the source network node for CHO preparation.

[0058] The apparatus also includes means for receiving an indication from a user equipment (UE) served by the apparatus in a network for triggering conditional handover (CHO) preparation with a plurality of target network nodes that are in a path in which the UE moves, and means for triggering the CHO preparation with the plurality of target network nodes by causing transmission of a cell identifier of a next target network node of the respective recipient target network node and a cell identifier of a previous network node of the recipient target network node to the respective recipient target network node.

[0059] A computer program product is provided, the computer program product comprising at least one non-transitory computer-readable medium having computer-executable program instructions stored thereon, the computer-executable program instructions for at least performing: triggering conditional handover (CHO) preparation to a plurality of target network nodes in a path along which a user equipment (UE) is determined to move. The CHO preparation comprises causing transmission of a cell identifier of a next target network node of a recipient target network node to the respective recipient target network node, and if the previous network node of the recipient target node is not the source network node of the cell identifier of the next target node, causing transmission of a cell identifier of the previous network node of the recipient target network node to the respective recipient target network node.

[0060] The computer executable program instructions also include program instructions for causing transmission of an indicator for triggering additional CHO preparations to other target network nodes and a list of cell identifiers of respective other target network nodes to the last network node triggered by the source network node for CHO preparation.

[0061] According to certain embodiments, the path on which the UE is determined to be moving includes a path from a source network node configured as a first network node to a second network node, to a third network node, and to a fourth network node, wherein the CHO preparation further includes causing transmission of a cell identifier of the third network node to the second network node, and causing transmission of a cell identifier of the fourth network node and a cell identifier of the second network node to the third network node.

[0062] The indicator and the list of cell identifiers for triggering additional CHO preparation are sent from the source network node to the fourth network node. The computer executable program instructions also include program instructions for causing transmission of an indication of a sequence of CHO conditions to be evaluated to the UE, wherein the respective CHO conditions are associated with respective network nodes in a path in which the UE is determined to be moving.

[0063] Another computer program product is provided, the computer program product comprising at least one non-transitory computer readable medium having computer executable program instructions stored thereon, the computer executable program instructions being for performing at least: receiving a cell identifier of a next target network node from a source network node, and performing early data forwarding to the next target network node.

[0064] The computer executable program instructions also include program instructions for receiving an indication from a source network node for triggering conditional handover (CHO) preparation to a plurality of target network nodes, and in response triggering CHO preparation to a plurality of target network nodes, the plurality of target network nodes indicated by the source network node.

[0065] The computer-executable program instructions also include program instructions for receiving a cell identifier of a previous network node from the source network node and, in response, causing transmission of a handover success message to the previous network node based on the cell identifier.

[0066] Another computer program product is provided, the computer program product including at least one non-transitory computer-readable medium having computer-executable program instructions stored thereon, the computer-executable program instructions for: receiving an indication of a sequence of conditional handover (CHO) conditions to be evaluated, wherein respective CHO conditions are associated with respective network nodes that are in a path along which a device is determined to move, and determining a conditional handover (CHO) condition to be evaluated for a next network node toward which the UE moves based on a cell identifier of a source network node and path information of the UE. The path information of the UE is received from a network entity and includes respective cell identifiers of the network nodes toward which the UE moves.

[0067] Another computer program product is provided, the computer program product including at least one non-transitory computer-readable medium having computer-executable program instructions stored thereon, the computer-executable program instructions for at least performing: causing transmission of an indicator for triggering CHO preparation for a target network node and a list of cell identifiers of the respective target network nodes to a source network node, the target network node receiving from the source network node an indication of a conditional handover (CHO) condition to be evaluated in a path along which the UE moves, wherein the respective CHO condition is associated with a respective one of the target network nodes according to the path, and evaluating the respective CHO condition of the next network node towards which the UE moves. The computer-executable program instructions also include program instructions for causing transmission of an indicator for triggering additional CHO preparations to other target network nodes and a list of cell identifiers of the respective other target network nodes to a last network node indicated by the source network node for CHO preparation.

[0068] A computer program product is provided, the computer program product comprising at least one non-transitory computer-readable medium having computer-executable program instructions stored thereon, the computer-executable program instructions being for performing at least: receiving an indication from a user equipment (UE) served by a source network node in a network, the indication being for triggering conditional handover (CHO) preparation with a plurality of target network nodes, the plurality of target network nodes being in a path in which the UE moves, and triggering the CHO preparation with the plurality of target network nodes by causing transmission of a cell identifier of a next target network node of the respective recipient target network nodes and a cell identifier of a previous network node of the recipient target network node to the recipient target network node. BRIEF DESCRIPTION OF THE DRAWINGS

[0069] Having generally described certain embodiments of the present disclosure, reference will now be made to the accompanying drawings, which are not necessarily drawn to scale, in which:

[0070] Figure 1 It spans two pages and is a diagram illustrating the switching of conditions;

[0071] Figure 2 is a schematic diagram illustrating example movement of a Hyperloop train moving between example cells in accordance with certain embodiments of the present disclosure;

[0072] Figure 3 is a block diagram of an apparatus specifically configured according to an example embodiment of the present disclosure; and

[0073] Figure 4 and Figure 5 Each spans two pages and is a flow diagram of operations implemented by a network entity according to certain embodiments of the present disclosure.

[0074] Fig. 6A , Figure 6B and Figure 7-10 is a flow diagram of operations implemented by a network entity according to certain embodiments of the present disclosure. DETAILED DESCRIPTION

[0075] Some embodiments of the present disclosure will be described more fully below with reference to the accompanying drawings, in which some but not all embodiments of the present disclosure are shown. In fact, various embodiments of the present disclosure are embodied in many different forms and should not be construed as being limited to the embodiments described herein; on the contrary, these embodiments are provided so that the present disclosure meets applicable legal requirements. The same figure numbers always refer to the same elements. As used herein, the terms "data", "content", "information" and similar terms may be used interchangeably to refer to data that can be sent, received and / or stored according to embodiments of the present disclosure. Therefore, the use of any such terms should not be viewed as limiting the spirit and scope of the embodiments of the present disclosure.

[0076] In addition, as used herein, the term "circuitry" refers to (a) a pure hardware circuit implementation (e.g., an implementation in an analog circuit system and / or a digital circuit system); (b) a combination of a circuit and (multiple) computer program products, including software and / or firmware instructions stored on one or more computer-readable memories, which work together to cause the device to perform one or more functions described herein; and (c) a circuit that requires software or firmware to operate even if the software or firmware is not physically present, such as (multiple) microprocessors or a portion of (multiple) microprocessors. This definition of "circuitry" applies to all uses of the term herein, including in any claims. As another example, as used herein, the term "circuitry" also includes an implementation including one or more processors and / or (multiple) portions thereof and accompanying software and / or firmware. As another example, for example, as used herein, the term "circuitry" also includes a baseband integrated circuit or application processor integrated circuit for a mobile phone, or a similar integrated circuit in a server, a cellular network device, other network equipment (such as a core network device), a field programmable gate array, and / or other computing devices.

[0077] Figure 3 An example of an apparatus 300 is provided, which is configured to function as a network entity, such as a UE 100, a network node or cell (such as, but not limited to, a next generation NodeB (gNB)), a source network node 102, a target network node 104, and / or other network nodes discussed herein.

[0078] The apparatus 300 includes a processing circuit system 302, a memory device 306, and a communication interface 304, which are associated with or communicate with it. The processing circuit system 302 communicates with the memory device via a bus to transfer information between components of the apparatus 300. The memory device 306 can be non-transitory and can include, for example, one or more volatile and / or non-volatile memories. In other words, for example, the memory device 306 can be an electronic storage device (e.g., a computer-readable storage medium) that includes a gate configured to store data (e.g., bits) that can be retrieved by a machine (e.g., a computing device such as a processing circuit system). The memory device 306 can be configured to store information, data, content, applications, instructions, etc., so that the apparatus can perform various functions according to the example embodiments of the present disclosure. For example, the memory device 306 can be configured to buffer input data for processing by the processing circuit system 302. Additionally or alternatively, the memory device 306 can be configured to store instructions executed by the processing circuit system 302.

[0079] In some embodiments, the device 300 may be embodied in various computing devices as described above. However, in some embodiments, the device may be embodied as a chip or a chipset. In other words, the device may include one or more physical packages (e.g., chips) that include materials, components, and / or wires on a structural assembly (e.g., a substrate). The structural assembly may provide physical strength, dimensional conservation, and / or limitations on electrical interactions for the component circuitry included thereon. Therefore, in some cases, the device may be configured to implement embodiments of the present disclosure on a single chip or as a single "system on a chip." Therefore, in some cases, a chip or chipset may constitute a component for performing one or more operations to provide the functionality described herein.

[0080] The processing circuit system 302 can be embodied in a variety of different ways. For example, the processing circuit system 302 can be embodied as one or more of various hardware processing components, such as at least one processor, coprocessor, microprocessor, controller, digital signal processor (DSP), processing element with or without attached DSP, or various other circuit systems, the various circuit systems including integrated circuits, such as ASIC (application-specific integrated circuit), FPGA (field programmable gate array), microcontroller unit (MCU), hardware accelerator, dedicated computer chip, etc. Therefore, in some embodiments, the processing circuit system may include one or more processing cores configured to execute independently. The multi-core processing circuit system can implement multi-processing within a single physical package. Additionally or alternatively, the processing circuit system may include one or more processors configured in series via a bus to implement independent execution of instructions, pipelines, and / or multithreading.

[0081] In an example embodiment, the processing circuit system 302 may be configured to execute instructions stored in the memory device 306 or otherwise accessible to the processing circuit system 302. Alternatively or additionally, the processing circuit system may be configured to perform hard-coded functions. Therefore, whether configured by hardware or software methods or by a combination thereof, the processing circuit system may represent an entity (e.g., physically embodied in a circuit system) that is capable of performing operations according to embodiments of the present disclosure while being configured accordingly. Therefore, for example, when the processing circuit system is embodied as an ASIC, FPGA, etc., the processing circuit system may be specially configured hardware for performing the operations described herein. As another example, when the processing circuit system 302 is embodied as an executor of instructions, the instructions may specifically configure the processing circuit system and / or the processor to perform the algorithms and / or operations described herein when the instructions are executed. However, in some cases, the processing circuit system 302 may be a processor of a specific device (e.g., an image or video processing system) that is configured to further configure the processing circuit system to employ embodiments of the present disclosure by instructions for performing the algorithms and / or operations described herein. Processing circuitry 302 may include a clock, an arithmetic logic unit (ALU), and logic gates configured to support operation of the processing circuitry.

[0082] The processing circuit system 302 may include or embody one or more types of circuit systems configured to perform specific functions. As described below, for example, the processing circuit system may embody one or more of the following: measurement reporting circuit system, CHO request initiation circuit system, CHO requirement transmission circuit system, triggering circuit system, CHO evaluation circuit system, RRC configuration message indication circuit system, CHO preparation triggering circuit system and / or early data forwarding circuit system.

[0083] The communication interface 304 can be any component, such as a device or circuit system embodied in hardware or a combination of hardware and software, which is configured to receive and / or send data, including media content in the form of video or image files, one or more audio tracks, etc. In this regard, the communication interface 304 may include, for example, an antenna (or multiple antennas) and supporting hardware and / or software for implementing communication with a wireless communication network. Alternatively, the communication interface may include a circuit system for interacting with (multiple) antennas to cause signal transmission via (multiple) antennas or processing the reception of signals received via (multiple) antennas. In some environments, the communication interface may alternatively or additionally support wired communication. Therefore, for example, the communication interface may include a communication modem and / or other hardware / software for supporting communication via cable, digital subscriber line (DSL), universal serial bus (USB) or other mechanisms.

[0084] Reference now Figure 4, an example sequence diagram implemented by, for example, an apparatus 300, such as a UE 100, a source gNB or network node 102 (cell 1), and / or multiple target gNBs or network nodes 104 (cell 2), 400 (cell 3), and 402 (cell 4) is discussed herein. When the path information of the UE is known in the network, but the UE is not necessarily aware of it, according to the first technology implementation Figure 4 The sequence diagram of .

[0085] exist Figure 4 In operation 1 of , apparatus 300 (such as UE 100) includes components for sending a measurement report to cell 1, such as processing circuit system 302 (e.g., measurement reporting circuit system), communication interface 304, etc. Cell 1 receives a cell list X from a network entity, such as including PCIs to be prepared along the path (operation 2). The list may include an ordered list of target cells, or an indication of the order of cells toward which the UE moves, so that apparatus 300 can trigger preparation of cells 2, 3, and 4 through components such as processing circuit system 302 and via communication interface 304, each of which has an Xn interface with the source gNB (cell 1).

[0086] exist Figure 4 In operation 3 of , apparatus 300 (such as a source network node (cell 1)) includes components for initiating a CHO request to cell 2, such as processing circuitry 302 (e.g., CHO request initiation circuitry), communication interface 304, etc., which also initiates early data forwarding from cell 2 to cell 3. In operation 4, cell 2 responds to cell 1 via a CHO request response. Operation 5 includes causing transmission of a CHO request to cell 3 using components such as processing circuitry 302 (e.g., CHO request transmission circuitry), communication interface 304, etc., initiating preparation of cell 3 using the source cell of the handover as an indication of cell 2, and further initiating execution of early data forwarding to cell 4. In Figure 4 In operation 7 of , a CHO request is sent from cell 1 to cell 4 by the apparatus 300 using components such as processing circuit system 302 (e.g., CHO request transmission circuit system) and communication interface 304, as well as a flag or indicator that triggers new or additional CHO preparations to additional target network nodes or a list of target cells. The list of target network nodes is also provided to cell 4 along with an indication of the path and / or order of cells to which the UE will travel. The apparatus 300 (such as cell 4) includes components such as processing circuit system 302 (e.g., triggering circuit system), communication interface 304, etc., for triggering iterations similar to the source network node in operation 8, continuing CHO preparations to the additional target network nodes in the path, and sending a CHO response.

[0087] In operation 9, the RRC reconfiguration message sent from the source network node to the UE by the apparatus 300 using components such as the processing circuit system 302 and the communication interface 304 indicates the serving cell PCI, and thus indicates the CHO execution conditions to be evaluated in the UE. In this regard, the apparatus 300 implemented as the UE 100 does not necessarily perform all CHO evaluations when the CHO conditions are received, but includes components such as the processing circuit system 302, the CHO evaluation circuit system and the memory device 306 for determining the next network node and the related CHO conditions to be evaluated based on the sequence of network nodes determined along the path. In this regard, after the UE receives the RRC reconfiguration, the UE can start evaluating the CHO conditions of the next target cell along the path.

[0088] In operation 10, the apparatus 300 (such as UE 100) includes components such as processing circuit system 302 (e.g., CHO evaluation circuit system) and communication interface 304 for receiving, determining or identifying an indication (such as PCI) of serving cell 1, and thus can use processing circuit system 302 to evaluate the CHO condition associated with the next target network node according to the path information provided by the network. After the CHO condition of cell 2 is satisfied (operation 12), UE 100 initiates random access to the identified network node using components such as processing circuit system 302, communication interface 304, etc. at operation 13, and receives a handover success message at operation 13. Data forwarding from cell 2 to cell 3 occurs at operation 14, and as shown in operation 15, UE 100 is now served by cell 2 while moving along the path. Such as using processing circuit system 302 (e.g., CHO evaluation circuit system), and according to operation 15, the apparatus 300 including UE 100 begins to evaluate only the CHO condition of cell 3 (based on the PCI of cell 3 indicated in the path information). After the CHO condition is satisfied in operation 16, the random access procedure of UE 100 to cell 3, the handover from cell 3 to cell 2 in operation 18 is successful, and the data forwarding of cell 3 in operation 19 is performed similarly to operations 12-14.

[0089] At operation 20, when the apparatus 300 (such as UE 100) is served by cell 3, UE 100 evaluates the CHO condition of cell 4, such as using processing circuit system 302 (e.g., CHO evaluation circuit system), and after the condition is satisfied (operation 21), performs a random access procedure to cell 4 using components such as communication interface 304 at operation 22. The apparatus 300 (such as cell 4) includes components such as processing circuit system 302 and communication interface 304 for causing the transmission of a handover success message to cell 3 at operation 23. At operation 24, cell 4 also begins to trigger new or additional CHO preparations with cells further along the path, such that Figure 4The illustrated operations are repeated iteratively, and as UE 100 moves along the path, cell 4 may serve as a source network node for other target network nodes.

[0090] It should be understood that Figure 4 The 4 cells are provided as examples only, and the source network node may prepare any number of cells for CHO. The last network node (e.g., cell 4) is instructed to trigger additional CHO preparations to other target network nodes, so that the cell then acts as the source network node for the additional target cells. Operation 24 indicates the responsibility of triggering the CHO preparations transferred from one source cell to another cell.

[0091] It will also be appreciated that in certain embodiments the target network node cell 4 may trigger new CHO preparations (operation 24 ) immediately after operation 8 , but provide for conditional reconfiguration of these preparations after the UE 100 completes execution of the handover to the target cell 4 in operation 22 .

[0092] Although Figure 4 is a sequence diagram of the operation of a first technique according to certain embodiments, wherein path information is known in the network, but Figure 5 is a sequence diagram of the operation of the second technique according to certain embodiments, where the UE 100 knows the path information.

[0093] Figure 5 and Figure 4 There are some similarities, but at least some differences as described below. As mentioned in aspect #6 and Figure 5 As described in operation 1 of , based on the cell list X in the path that the UE 100 will visit, the apparatus 300 embodied by the UE 100 includes components for notifying the serving cell 1 (source gNB) of the next candidate target cell, such as the processing circuit system 302 and the communication interface 304. After receiving the information, the apparatus 300 embodied by the source cell (cell 1) triggers the preparation of the candidate target network node 104 (cell 2), the target network node 400 (cell 3), and the target network node 402 (cell 4). The source gNB may not need to include the flag and the cell list X, because it can be notified by the UE 100, such as Figure 5 , as shown in operation 24, as described in further detail below (and with respect to aspect #7 described herein).

[0094] like Figure 5As shown in operation 1 of , the apparatus 300 (such as UE 100) has a list X of cells to be prepared along the path (the list is stored in the memory device 306), and also includes components for causing the transmission of an indication of preparing candidate target cells from the list X to the source gNB cell 1 (as described in operation 2), such as processing circuit system 302 and communication interface 304. As shown in operation 3, the apparatus 300 (such as the source gNB (cell 1)) includes components for triggering the preparation of cells 2, 3, and 4, such as processing circuit system 302 (e.g., cell preparation triggering circuit system), communication interface 304, etc., each of which has a corresponding gNB having an Xn interface with the source gNB. In operation 4, the apparatus 300 (such as cell 1) includes components for sending a CHO request to cell 2, initiating preparation of cell 2, and early data forwarding to cell 3, such as processing circuit system 302, communication interface 304, etc. In operation 5, cell 2 includes components, such as processing circuitry 302, communication interface 304, etc., for returning a CHO request response to cell 1.

[0095] In operation 6, the apparatus 300 embodied by the source network node gNB cell 1 includes components for sending a CHO request to cell 3, initiating preparation of cell 3, and early data forwarding to cell 4, such as processing circuit system 302, communication interface 304, etc. The source network node or gNB (cell 1) also indicates to cell 3 that the source cell of the handover is cell 2, so that cell 3 can later indicate a successful handover (operation 19). In operation 7, cell 3 includes components for returning a CHO request response to cell 1, such as processing circuit system 302, communication interface 304, etc.

[0096] In operation 8, the apparatus 300 embodied by the source network node gNB cell 1 includes components for sending a CHO request to cell 4, initiating preparation of cell 4, such as processing circuit system 302, communication interface 304, etc. The source network node or gNB (cell 1) also indicates to cell 4 that the source cell of the handover is cell 3, so that cell 4 can later indicate a successful handover (operation 25). In operation 9, the apparatus 300 embodied by cell 4 includes components for returning a CHO request response to cell 1, such as processing circuit system 302, communication interface 304, etc.

[0097] In operation 10, the source network node or source gNB cell 1 includes a component for indicating an RRC reconfiguration message to the UE 100, including a processing circuit system 302 (e.g., an RRC configuration message indicating circuit system), a communication interface 304, etc., and the RRC reconfiguration message includes the CHO conditions of the prepared cells (such as cells 2, 3 and 4).

[0098] As shown in operation 11, when UE 100 is served by cell 1, apparatus 300 embodied by UE 100 includes components, such as processing circuitry 302 (e.g., CHO evaluation circuitry), for evaluating a CHO condition of cell 2. After the CHO condition is satisfied in operation 12, UE 100 includes components, such as processing circuitry 302 and communication interface 304, for performing a random access procedure to cell 2. Using the components including processing circuitry 302 and communication interface 304, cell 2 indicates a handover success to cell 1 in operation 14, and starts data forwarding to cell 3 in operation 15.

[0099] When UE 100 moves toward cell 3 and / or after UE 100 starts to move toward cell 3, operations 16-20 include operations similar to operations 11-15. Operations 21-23 are similar to operations 11-13 and operations 16-18. In operation 24, UE 100 includes components such as processing circuit system 302 and communication interface 304 for indicating to cell 4 that a set of new candidate target cells and a cell list X along the path are prepared. In operation 25, cell 4 also indicates that the handover to cell 3 is successful using components such as processing circuit system 302 and communication interface 304. Cell 4 can also act as a source network node and can repeat the instructions regarding Figure 5 The process described includes triggering a new CHO preparation indicated by operation 26 .

[0100] It should be understood that Figure 5 The 4 cells are provided as examples only, and the source cell may prepare any number of cells for CHO. Thus, the CHO preparation triggered by the source network node may be triggered for any number of network nodes. The last network node (e.g., cell 4) is instructed to trigger additional CHO preparations to other target network nodes, such that the cell then acts as the source gNB for the additional cells. Operation 26 indicates the responsibility for triggering the CHO preparation to be transferred from one source cell to another source cell.

[0101] Fig. 6A is a message sent by a network entity (such as source gNB 102) or source network node 102 (such as Figure 4 1) is a flowchart of operations performed by the device 300 embodied in the cell.

[0102] In operation 600, the apparatus 300 embodied by a network entity (such as the source network node 102) may include components for triggering conditional handover (CHO) preparation to multiple target network nodes, such as processing circuit system 302 (e.g., CHO preparation triggering circuit system), communication interface 304, etc., the multiple target network nodes are in the path along which the user equipment (UE) is determined to move. For example, see the above aspects #1 and Figure 4In some embodiments, triggering CHO preparation includes operation 602.

[0103] In operation 602, the apparatus 300 embodied by a network entity, such as the source network node 102, may include means for triggering CHO preparation by causing transmission of a cell identifier of a next target network node of a recipient target network node to the corresponding recipient target network node, such as the processing circuit system 302 (e.g., CHO preparation triggering circuit system), the communication interface 304, etc. In this regard, the means for triggering CHO preparation includes means for causing transmission of a cell identifier of a next target network node of the recipient target network node to the corresponding recipient target network node. For example, see Figure 4 In addition, according to operation 602, based on the fact that the previous network node of the recipient target node is not the device, the device 300 embodied by the network entity (such as the source network node 102) may include a component for causing the transmission of the cell identifier of the previous network node of the recipient target network node, such as the processing circuit system 302, the communication interface 304, etc. In other words, if the previous network node of the recipient target node is not the device, some example embodiments cause the transmission of the cell identifier of the previous network node. For example, see aspects #3 and Figure 4 Operations 5 and 7.

[0104] In operation 604, the apparatus 300 embodied by a network entity, such as the source network node 102, may include means for causing an indicator for triggering additional CHO preparations to other target network nodes, and a transmission of a list of cell identifiers of the respective other target network nodes to the last network node for which CHO preparations are triggered by the apparatus, such as the processing circuit system 302, the communication interface 304, etc. See at least aspects #4 and Figure 4 Operation 7. An indicator and a list of cell identifiers for triggering additional CHO preparation are sent from the apparatus (eg, source network node 102) to a fourth network node. See at least aspect #3 described herein.

[0105] In operation 606, the apparatus 300 embodied by a network entity (such as the source network node 102) may include means, such as the processing circuit system 302, the communication interface 304, etc., for causing transmission of an indication of a sequence of CHO conditions to be evaluated to the UE, wherein the respective CHO conditions are associated with respective network nodes in the path in which the UE is determined to be moving. See at least aspects #5 and Figure 4 Operation 9. For example, the serving cell may indicate that when the UE is served by serving cell 1, the CHO execution condition of target cell 2 should be evaluated, and when the UE is served by cell 2, the CHO execution condition of target cell 3 should be evaluated, and so on.

[0106] Figure 6B is a flow chart of operations performed by an apparatus 300 that may be embodied by a network entity (such as a source gNB) or a network node (such as cell 1) according to a first method and example embodiment. According to an example embodiment, the path along which the UE is determined to be moving includes a path from the apparatus (a first network node, such as Figure 4 source network node 102) to a second network node (eg, Figure 4 2), to a third network node (eg, Figure 4 3) and to a fourth network node (eg, Figure 4 4) of the cell.

[0107] In operation 610, the apparatus 300 embodied by a network entity (such as the source network node 102) may include components for triggering CHO preparation, such as the processing circuit system 302 (e.g., CHO preparation triggering circuit system), the communication interface 304, etc., the CHO preparation including causing the transmission of the cell identifier of the third network node to the second network node. See at least aspects #2 and #4 described herein. Figure 4 Operation 3.

[0108] In operation 612, the apparatus 300 embodied by a network entity, such as the source network node 102, may include means, such as the processing circuit system 302, the communication interface 304, etc., for causing the transmission of the cell identifier of the fourth network node and the cell identifier of the second network node to the third network node. Figure 4 Operation 5.

[0109] In operation 614, the apparatus 300 embodied by a network entity (such as the source network node 102) may include means for causing transmission of an indicator and a list of cell identifiers for triggering additional CHO preparation to a fourth network node, such as the processing circuit system 302, the communication interface 304, etc. See at least aspects #4 and Figure 4 Operation 7.

[0110] Figure 7 is a network entity (such as a target gNB) or a network node (such as Figure 4 and Figure 5 4. The present invention is a flowchart of operations performed by the apparatus 300 embodied in any one of the cells 2-4 in the target network (eg, the target network nodes 104, 400, and 402).

[0111] In operation 700, the apparatus 300 embodied by a network entity (such as the target network node 104) may include components for receiving a cell identifier of a next target network node from a source network node, such as a processing circuit system 302, a communication interface 304, etc. Referring at least to aspects #2 and #3 described herein, Figure 4 Operations 3, 5, and 7 and Figure 5 Operations 4, 6 and 8.

[0112] In operation 702, the apparatus 300 embodied by a network entity (such as a target network node 104) may include components for performing early data forwarding to a next target network node, such as a processing circuit system 302 (e.g., an early data forwarding circuit system), a communication interface 304, etc. Referring at least to aspects #2 and #3 described herein, Figure 4 Operations 3, 5, and 7 and Figure 5 Operations 4, 6 and 8.

[0113] In operation 704, the apparatus 300 embodied by a network entity (such as the target network node 104) may include components, such as processing circuitry 302 (e.g., CHO preparation triggering circuitry), communication interface 304, etc., for receiving an indication from a source network node for triggering conditional handover (CHO) preparation to a plurality of target network nodes, and in response, triggering CHO preparation to the plurality of target network nodes, the plurality of target network nodes being indicated by the source network node. See at least aspects #4 and Figure 4 Operation 24.

[0114] Figure 8 is a flow chart of operations performed by an apparatus 300 embodied by a network entity (such as UE 100) according to the first technique.

[0115] In operation 800, an apparatus 300 embodied by a network entity, such as a UE 100, may include components, such as a processing circuit system 302, a communication interface 304, etc., for receiving an indication of a sequence of conditional handover (CHO) conditions to be evaluated, wherein the respective CHO conditions are associated with respective network nodes that are in a path along which the apparatus is determined to move.

[0116] In operation 802, the device 300 embodied by a network entity (such as UE 100) may include components, such as a processing circuit system 302, a communication interface 304, etc., for determining a conditional handover (CHO) condition to be evaluated for a next network node toward which the device (e.g., UE) moves based on a cell identifier of a source network node and path information of the device (e.g., UE).

[0117] Fig. 9is a flow chart of operations performed by an apparatus 300 embodied by a network entity (such as UE 100) according to the second technique.

[0118] In operation 900, the apparatus 300 embodied by a network entity (such as UE 100) may include components, such as processing circuit system 302, communication interface 304, etc., for causing transmission of an indicator for triggering CHO preparation for a target network node and a cell identifier list of the corresponding target network node to a source network node, the target network node being in a path along which the apparatus moves. See at least aspects #6 and #7 described herein. Figure 5 Operations 1 and 2.

[0119] In operation 902, the apparatus 300 embodied by a network entity, such as the UE 100, may include means, such as the processing circuit system 302, the communication interface 304, etc., for receiving an indication of a conditional handover (CHO) condition to be evaluated from a source network node, wherein the corresponding CHO condition is associated with a corresponding one of the target network nodes according to the path. For example, see Figure 5 The RRC reconfiguration indicated in operation 10.

[0120] In operation 904, the apparatus 300 embodied by a network entity (such as UE 100) may include components for evaluating the corresponding CHO condition of the next network node toward which the apparatus (e.g., UE) moves, such as processing circuit system 302, communication interface 304, etc. See at least aspects #8 and Figure 5 Operations 11, 16 and 21.

[0121] In operation 906, the apparatus 300 embodied by a network entity (such as UE 100) may include means for causing transmission of an indicator for triggering additional CHO preparations to other target network nodes and a list of cell identifiers of the respective other target network nodes to the last network node indicated by the source network node for CHO preparation, such as the processing circuit system 302, the communication interface 304, etc. See at least aspects #7 and #8 described herein. Figure 5 Operation 24.

[0122] Fig.10 is a network entity (such as a source gNB) or a network node (such as Figure 5 1) is a flowchart of operations performed by the device 300 embodied in the cell.

[0123] In operation 1000, an apparatus 300 embodied by a network entity, such as a source network node 102, may include means for receiving an indication from a user equipment (UE) served by the apparatus in a network, the indication for triggering a conditional handover (CHO) preparation with a plurality of target network nodes, such as a processing circuit system 302, a communication interface 304, etc., the plurality of target network nodes being in a path in which the UE is moving. See at least aspects #6 and #7 described herein. Figure 5 Operation 2.

[0124] In operation 1002, the apparatus 300 embodied by a network entity, such as a source network node 102, may include components, such as a processing circuit system 302 (e.g., a CHO preparation triggering circuit system), a communication interface 304, etc., for triggering CHO preparation with a plurality of target network nodes by causing transmission of a cell identifier of a next target network node of the corresponding recipient target network node and a cell identifier of a previous network node of the recipient target network node to the recipient target network node. See at least Figure 5 Aspects #1 and #3 and operations 3, 4, 6 and 8.

[0125] Thus, certain embodiments disclosed herein enable the network and associated network entities to reduce signaling overhead associated with early data forwarding to more cells than required along the path that the UE is moving along that might otherwise occur. Certain embodiments also enable the target node to know to which handover source gNB to send a "handover success" message in CHO. For example, the target gNB or network node 400 (e.g., cell 3) sends a "handover success" message to the source gNB or network node 102 to indicate to the source gNB or network node 104 that the UE has performed a CHO execution (the source gNB or network node 104 does not know this before receiving the information). Using this information, the source gNB network node 102 can stop scheduling and send a final sequence number (SN) state transfer message that indicates to the target gNB the ID of the next downlink packet that should be delivered to the UE in the downlink and the next uplink packet that should be delivered to the UPF. When the UE is served by gNB1, the target gNB or network node 400 or cell 3 is prepared in advance. Therefore, the target gNB or network node 400 or cell 3 does not know where to send the handover success. In this case, the source gNB or network node 104 (cell 1) notifies the target network node of the ID of the previous cell along the path.

[0126] Certain embodiments instruct the target gNB to control the last prepared candidate target cell to trigger CHO preparation of the next upcoming candidate target cell along the path, and reduce the complexity of the UE by limiting the measurement evaluation to the CHO condition of the next target cell along the path. Therefore, the example embodiments are particularly useful in high-speed train scenarios, where continuous connectivity is also required and the path of the UE is known or can be determined.

[0127] Figure 1 and Figure 4 , Figure 5 , Fig. 6A , Figure 6B and Figure 7-10 The message flow and flow chart depicting the method according to the example embodiment of the present disclosure are illustrated. It should be understood that each box of the message flow can be implemented in various ways, such as hardware, firmware, processor, circuit tradition, and / or other communication devices associated with the execution of software including one or more computer program instructions. For example, one or more of the above processes can be embodied by computer program instructions. In this regard, the computer program instructions embodying the above process are stored by the memory device 306 of the device 300 adopting the embodiment of the present disclosure, and are executed by the processing circuit system 302 (such as one or more processors). As will be understood, any such computer program instructions can be loaded onto a computer or other programmable device (e.g., hardware) to produce a machine so that the resulting computer or other programmable device implements the functions specified in the flowchart box. These computer program instructions are stored in a computer-readable memory, which instructs the computer or other programmable device to operate in a specific manner so that the instructions stored in the computer programmable memory produce an article, and the execution of the article implements the functions specified in the flowchart box. Computer program instructions are loaded onto a computer or other programmable device to cause a series of operations to be performed on the computer or other programmable device, thereby producing a computer-implemented process, so that the instructions executed in the computer or other programmable device provide operations for implementing the functions specified in the flowchart blocks.

[0128] Therefore, the blocks of the flowchart and message flow support the combination of components for performing the specified functions and the combination of operations for performing the specified functions. It will also be understood that one or more blocks of the flowchart and the combination of blocks in the flowchart can be implemented by a computer system based on special-purpose hardware or a combination of special-purpose hardware and computer instructions that performs the specified functions.

[0129] Many modifications and other embodiments of the disclosure described herein will occur to those skilled in the art with the benefit of the teachings presented in the above description and the associated drawings. Therefore, it should be understood that the disclosure is not limited to the specific embodiments disclosed, and modifications and other embodiments are intended to be included within the scope of the appended claims.

[0130] In addition, although the above description and the related drawings describe certain embodiments in the context of certain example combinations of elements and / or functions, it should be understood that alternative embodiments provide different combinations of elements and / or functions without departing from the scope of the appended claims. In this regard, for example, as described in some of the appended claims, it is also possible to consider elements and functional combinations that are different from the elements and / or functions explicitly described above. Although specific terms are used herein, they are used only in a general and descriptive sense, and not for the purpose of limitation.

[0131] Although some variations are described in detail above, other modifications or additions are possible. In particular, other features and / or variations are provided in addition to those described herein. In addition, the above implementations involve various combinations and subcombinations of the disclosed features and / or combinations and subcombinations of several other features described above. Other embodiments are provided within the scope of the following claims.

[0132] If desired, the different functions discussed herein may be performed in a different order and / or concurrently with each other. In addition, if desired, one or more of the above functions may be optional or may be combined. Although various aspects of some embodiments are listed in the independent claims, other aspects in some embodiments include other combinations of features in the described embodiments and / or dependent claims with features of the independent claims, rather than just the combinations explicitly listed in the claims. It should also be noted herein that although certain embodiments are described above, these descriptions should not be considered restrictive. On the contrary, several changes and modifications may be made without departing from the scope of some embodiments defined in the appended claims. Other embodiments may be within the scope of the following claims. The term "based on" includes "at least based on". Unless otherwise specified, the term "such as" is used to mean "for example".

[0133] Therefore, it should be emphasized again that the various embodiments described herein are presented only as illustrative examples and should not be interpreted as limiting the scope of the claims. For example, alternative embodiments may utilize communication system configurations, user equipment configurations, base station configurations, identity request procedures, messaging protocols, and message formats that are different from the above-described illustrative embodiments. In this regard, at least some embodiments have been described in conjunction with a particular type of network (e.g., a 5G NR network). However, the disclosed embodiments may be used in conjunction with other types of networks, including those developed and implemented below. These and many other alternative embodiments within the scope of the appended claims will be clear to those skilled in the art.

Claims

1. An apparatus comprising at least one processor and at least one memory storing instructions, the instructions, when executed by the at least one processor, causing the apparatus to at least: triggering a conditional handover (CHO) preparation to a plurality of target network nodes in a path along which a user equipment (UE) is determined to move, wherein the CHO preparation comprises: causing the transmission of a cell identifier of a next target network node of the corresponding receiving target network node to the receiving target network node, and causing the transmission of a cell identifier of the previous network node of the receiving target network node to the receiving target network node based on the fact that the previous network node of the receiving target network node is not the device.

2. The apparatus of claim 1 , wherein the instructions, when executed by the at least one processor, further cause the apparatus to at least: causing transmission of an indicator for triggering additional CHO preparations to other target network nodes, and a list of cell identifiers of respective other target network nodes, to a last network node for which CHO preparations are triggered by the apparatus.

3. The apparatus according to claim 1 or 2, wherein the path on which the UE is determined to move comprises a path from the apparatus configured as a first network node to a second network node, to a third network node, and to a fourth network node, wherein the CHO preparation further comprises: causing transmission of a cell identifier of the third network node to the second network node; as well as causing transmission of a cell identifier of the fourth network node and a cell identifier of the second network node to the third network node. 4 . The apparatus according to claim 3 , wherein the indicator and the cell identifier list for triggering the additional CHO preparation are sent from the apparatus to the fourth network node.

5. The apparatus of any one of claims 1 to 4, wherein the instructions, when executed by the at least one processor, further cause the apparatus to at least: The method causes transmission to the UE of an indication of a sequence of CHO conditions to be evaluated, wherein respective CHO conditions are associated with respective network nodes in the path within which the UE is determined to be moving.

6. An apparatus comprising at least one processor and at least one memory storing instructions, the instructions, when executed by the at least one processor, causing the apparatus to at least: receiving a cell identifier of a next target network node from the source network node; and Early data forwarding is performed to the next target network node.

7. The apparatus of claim 6, wherein the instructions, when executed by the at least one processor, further cause the apparatus to at least: An indication for triggering conditional handover (CHO) preparation to a plurality of target network nodes is received from the source network node, and in response, the CHO preparation is triggered to the plurality of target network nodes, the plurality of target network nodes being indicated by the source network node.

8. The apparatus of claim 6 or 7, wherein the instructions, when executed by the at least one processor, further cause the apparatus to at least: A cell identifier of a previous network node is received from the source network node, and in response, transmission of a handover success message is caused to the previous network node based on the cell identifier.

9. An apparatus comprising at least one processor and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus to at least: receiving an indication of a sequence of conditional handover (CHO) conditions to be evaluated, wherein a respective CHO condition is associated with a respective network node that is in a path along which the apparatus is determined to move; and Based on a cell identifier of the source network node and path information of the device, a conditional handover (CHO) condition to be evaluated of a next network node towards which the device moves is determined.

10. The apparatus of claim 9, wherein the path information of the apparatus is received from a network entity and comprises respective cell identifiers of network nodes towards which the apparatus is moving.

11. An apparatus comprising at least one processor and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus to at least: causing transmission of an indicator for triggering CHO preparation for a target network node and a list of cell identifiers of the corresponding target network nodes to the source network node, the target network nodes being in the path along which the apparatus moves; receiving, from the source network node, an indication of a conditional handover (CHO) condition to be evaluated, wherein a respective CHO condition is associated with a respective one of the target network nodes according to the path; and The corresponding CHO condition of the next network node toward which the device moves is evaluated.

12. The apparatus of claim 11, wherein the instructions, when executed by the at least one processor, further cause the apparatus to at least: Causing transmission of an indicator for triggering additional CHO preparations to other target network nodes, and a list of cell identifiers of respective other target network nodes, to a last network node indicated by the source network node for CHO preparation.

13. An apparatus comprising at least one processor and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus to at least: receiving an indication from a user equipment (UE) served by the apparatus in a network, the indication being used to trigger conditional handover (CHO) preparation with a plurality of target network nodes that are in a path along which the UE moves; and CHO preparation with the plurality of target network nodes is triggered by causing transmission of a cell identifier of a next target network node of the respective recipient target network nodes and a cell identifier of a previous network node of the recipient target network node to the recipient target network node.

14. An apparatus comprising: Means for triggering conditional handover (CHO) preparation to a plurality of target network nodes in a path along which a user equipment (UE) is determined to move, wherein the means for CHO preparation comprises: A means for causing transmission of a cell identifier of a next target network node of a corresponding recipient target network node to the recipient target network node, and if a previous network node of the recipient target node is not the device, causing transmission of a cell identifier of the previous network node of the recipient target network node to the recipient target network node.

15. The apparatus according to claim 14, further comprising: Means for causing transmission of an indicator for triggering additional CHO preparations towards other target network nodes, and a list of cell identifiers of respective other target network nodes, to a last network node for which CHO preparation is triggered by said apparatus.

16. The apparatus according to claim 14 or 15, wherein the path on which the UE is determined to move comprises a path from the apparatus configured as a first network node to a second network node, to a third network node, and to a fourth network node, wherein the means for CHO preparation further comprises: means for causing transmission of a cell identifier of the third network node to the second network node; as well as Means for causing transmission of a cell identifier of the fourth network node and a cell identifier of the second network node to the third network node.

17. The apparatus according to claim 16, wherein the indicator for triggering the additional CHO preparation and the cell identifier list are sent from the apparatus to the fourth network node.

18. The device according to any one of claims 14 to 17, further comprising: Means for causing transmission to the UE of an indication of a sequence of CHO conditions to be evaluated, wherein respective CHO conditions are associated with respective network nodes in the path within which the UE is determined to be moving.

19. An apparatus comprising: means for receiving a cell identifier of a next target network node from a source network node; as well as Means for performing early data forwarding to the next target network node.

20. The apparatus according to claim 19, further comprising: Means for receiving from the source network node an indication for triggering conditional handover (CHO) preparation to a plurality of target network nodes, and means for triggering the CHO preparation to the plurality of target network nodes in response, the plurality of target network nodes being indicated by the source network node.

21. The apparatus according to claim 19 or 20, further comprising: Means for receiving a cell identifier of a previous network node from the source network node, and means for causing, in response, transmission of a handover success message to the previous network node based on the cell identifier.

22. An apparatus comprising: means for receiving an indication of a sequence of conditional handover (CHO) conditions to be evaluated, wherein respective CHO conditions are associated with respective network nodes in a path along which the apparatus is determined to move; as well as Means for determining a conditional handover (CHO) condition to be evaluated for a next network node towards which the device moves based on a cell identifier of a source network node and path information for the device.

23. The apparatus of claim 22, wherein the path information of the apparatus is received from a network entity and comprises respective cell identifiers of network nodes towards which the apparatus is moving.

24. An apparatus comprising: means for causing transmission to a source network node of an indicator for triggering CHO preparation for a target network node, and a corresponding list of cell identifiers of said target network node, said target network node being in the path along which said apparatus moves; means for receiving, from the source network node, an indication of a conditional handover (CHO) condition to be evaluated, wherein a respective CHO condition is associated with a respective one of the target network nodes according to the path; as well as Means for evaluating a corresponding CHO condition of a next network node toward which the device moves.

25. The apparatus according to claim 24, further comprising: Means for causing transmission of an indicator for triggering additional CHO preparations towards other target network nodes and a list of cell identifiers of respective other target network nodes to a last network node indicated by said source network node for CHO preparation.

26. An apparatus comprising: means for receiving an indication from a user equipment (UE) served by the apparatus in a network, the indication for triggering conditional handover (CHO) preparation with a plurality of target network nodes, the plurality of target network nodes being in a path along which the UE moves; as well as Means for triggering CHO preparation with the plurality of target network nodes by causing transmission of a cell identifier of a next target network node of a respective recipient target network node and a cell identifier of a previous network node of the recipient target network node to the recipient target network node.

27. A method comprising: triggering a conditional handover (CHO) preparation to a plurality of target network nodes in a path along which a user equipment (UE) is determined to move, wherein the CHO preparation comprises: causing transmission of a cell identifier of a next target network node of the corresponding receiving target network node to the receiving target network node, and causing transmission of a cell identifier of the previous network node of the receiving target network node to the receiving target network node if the previous network node of the receiving target node is not the source network node of the cell identifier of the next target node.

28. The method according to claim 27, further comprising: causing transmission of an indicator for triggering additional CHO preparations towards other target network nodes, and a list of cell identifiers of respective other target network nodes, to the last network node for which CHO preparations were triggered by the source network node.

29. The method according to claim 27 or 28, wherein the path on which the UE is determined to move comprises a path from the source network node configured as the first network node to a second network node, to a third network node, and to a fourth network node, wherein the CHO preparation further comprises: causing transmission of a cell identifier of the third network node to the second network node; as well as causing transmission of a cell identifier of the fourth network node and a cell identifier of the second network node to the third network node.

30. The method of claim 27, wherein the indicator and the cell identifier list for triggering the additional CHO preparation are sent from the source network node to the fourth network node.

31. The method according to any one of claims 27 to 30, further comprising: The method causes transmission to the UE of an indication of a sequence of CHO conditions to be evaluated, wherein respective CHO conditions are associated with respective network nodes in the path within which the UE is determined to be moving.

32. A method comprising: receiving a cell identifier of a next target network node from the source network node; as well as Early data forwarding is performed to the next target network node.

33. The method of claim 32, further comprising: An indication for triggering conditional handover (CHO) preparation to a plurality of target network nodes is received from the source network node, and in response, the CHO preparation is triggered to the plurality of target network nodes, the plurality of target network nodes being indicated by the source network node.

34. The method according to claim 32 or 33, further comprising: A cell identifier of a previous network node is received from the source network node, and in response, transmission of a handover success message is caused to the previous network node based on the cell identifier.

35. A method comprising: receiving an indication of a sequence of conditional handover (CHO) conditions to be evaluated, wherein a respective CHO condition is associated with a respective network node in a path along which a user equipment (UE) is determined to move; as well as Based on a cell identifier of a source network node and path information of the UE, a conditional handover (CHO) condition to be evaluated for a next network node towards which the UE moves is determined.

36. The method of claim 35, wherein the path information of the UE is received from a network entity and comprises a corresponding cell identifier of a network node towards which the UE is moving.

37. A method comprising: causing transmission of an indicator for triggering CHO preparation for a target network node and a corresponding list of cell identifiers of the target network node to a source network node, the target network node being in a path along which a user equipment (UE) is moving; receiving, from the source network node, an indication of a conditional handover (CHO) condition to be evaluated, wherein a respective CHO condition is associated with a respective one of the target network nodes according to the path; as well as The corresponding CHO condition of the next network node toward which the UE moves is evaluated.

38. The method of claim 37, further comprising: Causing transmission of an indicator for triggering additional CHO preparations to other target network nodes, and a list of cell identifiers of respective other target network nodes, to a last network node indicated by the source network node for CHO preparation.

39. A method comprising: receiving an indication from a user equipment (UE) served by a source network node in a network, the indication being used to trigger conditional handover (CHO) preparation with a plurality of target network nodes, the plurality of target network nodes being in a path in which the UE is moving; as well as CHO preparation with the plurality of target network nodes is triggered by causing transmission of a cell identifier of a next target network node of the respective recipient target network nodes and a cell identifier of a previous network node of the recipient target network node to the recipient target network node.

40. A computer program product comprising at least one non-transitory computer-readable medium, the at least one non-transitory computer-readable medium including program instructions stored thereon, the program instructions for performing at least the following: triggering a conditional handover (CHO) preparation to a plurality of target network nodes in a path along which a user equipment (UE) is determined to move, wherein the CHO preparation comprises: causing transmission of a cell identifier of a next target network node of the corresponding receiving target network node to the receiving target network node, and causing transmission of a cell identifier of the previous network node of the receiving target network node to the receiving target network node if the previous network node of the receiving target node is not the source network node of the cell identifier of the next target node.

41. The computer program product of claim 40, wherein the program instructions further comprise program instructions for: causing transmission of an indicator for triggering additional CHO preparations towards other target network nodes, and a list of cell identifiers of respective other target network nodes, to the last network node for which CHO preparations were triggered by the source network node.

42. The computer program product of claim 40 or 41, wherein the path on which the UE is determined to move comprises a path from the source network node configured as a first network node to a second network node, to a third network node, and to a fourth network node, wherein the CHO preparation further comprises: causing transmission of a cell identifier of the third network node to the second network node; as well as causing transmission of a cell identifier of the fourth network node and a cell identifier of the second network node to the third network node.

43. The computer program product of claim 42, wherein the indicator and the list of cell identifiers for triggering the additional CHO preparation are sent from the source network node to the fourth network node.

44. A computer program product according to any one of claims 41 to 43, wherein the program instructions further comprise program instructions for: The method causes transmission to the UE of an indication of a sequence of CHO conditions to be evaluated, wherein respective CHO conditions are associated with respective network nodes in the path within which the UE is determined to be moving.

45. A computer program product comprising at least one non-transitory computer-readable medium, the at least one non-transitory computer-readable medium including program instructions stored thereon, the program instructions for at least performing the following: receiving a cell identifier of a next target network node from the source network node; and Early data forwarding is performed to the next target network node.

46. ​​The computer program product of claim 45, wherein the program instructions further comprise program instructions for: An indication for triggering conditional handover (CHO) preparation to a plurality of target network nodes is received from the source network node, and in response, the CHO preparation is triggered to the plurality of target network nodes, the plurality of target network nodes being indicated by the source network node.

47. A computer program product according to claim 45 or 46, wherein the program instructions further comprise program instructions for: A cell identifier of a previous network node is received from the source network node, and in response, transmission of a handover success message is caused to the previous network node based on the cell identifier.

48. A computer program product comprising at least one non-transitory computer-readable medium, the at least one non-transitory computer-readable medium including program instructions stored thereon, the program instructions for performing at least the following: receiving an indication of a sequence of conditional handover (CHO) conditions to be evaluated, wherein a respective CHO condition is associated with a respective network node in a path along which a user equipment (UE) is determined to move; and Based on a cell identifier of a source network node and path information of the UE, a conditional handover (CHO) condition to be evaluated for a next network node towards which the UE moves is determined.

49. The computer program product of claim 48, wherein the path information for the UE is received from a network entity and includes respective cell identifiers of network nodes towards which the UE is moving.

50. A computer program product comprising at least one non-transitory computer-readable medium, the at least one non-transitory computer-readable medium including program instructions stored thereon, the program instructions for performing at least the following: causing transmission to a source network node of an indicator for triggering CHO preparation to a target network node, and a list of cell identifiers of the corresponding target network nodes, the target network nodes being in a path along which a user equipment (UE) is moving; receiving, from the source network node, an indication of a conditional handover (CHO) condition to be evaluated, wherein a respective CHO condition is associated with a respective one of the target network nodes according to the path; as well as The corresponding CHO condition of the next network node toward which the UE moves is evaluated.

51. The computer program product of claim 50, wherein the program instructions further comprise program instructions for: Causing transmission of an indicator for triggering additional CHO preparations to other target network nodes, and a list of cell identifiers of respective other target network nodes, to a last network node indicated by the source network node for CHO preparation.

52. A computer program product comprising at least one non-transitory computer-readable medium, the at least one non-transitory computer-readable medium including program instructions stored thereon, the program instructions for performing at least the following: receiving an indication from a user equipment (UE) served by a source network node in a network, the indication being used to trigger conditional handover (CHO) preparation with a plurality of target network nodes, the plurality of target network nodes being in a path in which the UE is moving; and CHO preparation with the plurality of target network nodes is triggered by causing transmission of a cell identifier of a next target network node of the respective recipient target network nodes and a cell identifier of a previous network node of the recipient target network node to the recipient target network node.

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