Method and device for supporting data forwarding

Abstract

The embodiment of the invention relates to a method and equipment for supporting data forwarding. An example apparatus, such as a candidate target master node (MN), may include a processor configured to determine routing optimization information for early data forwarding associated with one or more candidate target secondary nodes (SNs) prepared by at least the MN, wherein the early data forwarding is a conditional handover (CHO) for a secondary cell group (SCG) with a user equipment (UE); and a transceiver coupled to the processor and configured to transmit the routing optimized information to a source MN.

Description

Technical Field

[0001] Embodiments of the present application generally relate to wireless communication techniques, and more particularly, to methods and apparatus for supporting data forwarding, such as supporting early data forwarding for conditional handover (CHO) with a secondary cell group (SCG) of a user equipment (UE). Background Art

[0002] Wireless communication systems are widely deployed to provide various telecommunication services, such as telephony, video, data, messaging, broadcasts, and the like. Wireless communication systems may employ multiple-access technologies capable of supporting communication with multiple users by sharing available system resources (e.g., time, frequency, and power). Examples of wireless communication systems include fourth-generation (4G) systems (e.g., Long Term Evolution (LTE) systems, LTE-Advanced (LTE-A) systems, or LTE-A Pro systems) and fifth-generation (5G) systems (which may also be referred to as New Radio (NR) systems).

[0003] When a UE moves from one cell to another, a serving cell change will be performed at some point. Traditionally, serving cell changes are accomplished through explicit radio resource control (RRC) reconfiguration signaling to trigger synchronization of the target cell based on Layer 3 (L3) measurement reports, which typically results in long latency, high overhead, and long outage times. Therefore, CHO (Cell Handover) was introduced to improve handover performance. It is defined as a handover performed by the UE when one or more handover execution conditions are met. The UE will begin evaluating the execution conditions after receiving the CHO configuration and stop evaluating the execution conditions after performing the handover.

[0004] Regarding SCG, it is a service cell group associated with a secondary node (SN), including a primary secondary cell (PSCell) and optionally one or more secondary cells (SCells). In a multi-radio (MR) dual connectivity (DC) scenario, the UE will perform CHO from the source master node (MN) toward a potential target MN, and will perform conditional PSCell addition (CPA) or conditional PSCell change (CPC) toward the potential SN. CPA is defined as a PSCell addition performed by the UE when the execution condition is met, and CPC is defined as a PSCell change performed by the UE when the execution condition is met. In short, this scenario is called CHO with SCG. For CHO with SCG, there are multiple potential target MNs and one target SCG (or only one potential target SCG) or multiple potential target SCGs. Regarding potential target MNs, they may also be referred to as or regarded as target MNs, candidate target MNs, candidate MCGs, candidate target MCGs, target MCGs, or candidate MNs, etc. Regarding the target SCG or potential target SCG, it may also be referred to or regarded as a candidate target SCG, candidate SCG, candidate target SN, target SN or candidate SN, etc.

[0005] To reduce data forwarding delays or interruptions, early data forwarding is introduced for CHO and CPA / CPC, where data forwarding to multiple potential target nodes is initiated in advance. If early data forwarding is applied, the source node (e.g., source MN or source SN) will initiate data forwarding to the potential target nodes of interest before the UE performs handover. Because there are multiple candidate target MNs (e.g., up to 8 according to current specifications) and each candidate target MN can prepare multiple candidate target SNs (e.g., up to 8 according to current specifications) for CHO with the SCG, multiple data forwarding paths exist for the same UE. Without data forwarding optimization, data would be sent via multiple paths, which in some scenarios would abuse network resources.

[0006] In view of the above, the industry desires to improve technology for data forwarding for CHO with SCG. Summary of the Invention

[0007] One objective of embodiments of the present application is to provide a technical solution for supporting data forwarding, for example, a method and apparatus for supporting data forwarding to at least improve early data forwarding for CHO with SCG.

[0008] Some embodiments of the present application provide a MN, such as a candidate target MN, comprising: a processor configured to: determine information for route optimization for early data forwarding associated with at least one or more candidate target SNs prepared by the MN, wherein the early data forwarding is for CHO with an SCG of a UE; and a transceiver coupled to the processor and configured to: transmit the information for route optimization to a source MN.

[0009] In some embodiments of the present application, the transceiver is configured to: receive an identifier of the candidate target SN from a candidate target SN among the one or more candidate target SNs, wherein the identifier of the candidate target SN is a globally unique identifier.

[0010] In some embodiments of the present application, the information of route optimization indicates at least one of the following: an identifier of one candidate target SN among the one or more candidate target SNs; a random number assigned at the one candidate target SN; or an indicator of the same candidate target SN, indicating that the data forwarding address associated with the early data forwarding will be mapped to the same data forwarding address of the one candidate target SN.

[0011] According to some embodiments of the present application, the route optimization information further indicates an estimated arrival probability of the UE toward the candidate target SN prepared by the MN.

[0012] According to some embodiments of the present application, the transceiver is configured to: receive information indicating that the same data forwarding address is shared by other candidate target MNs and the MN, so that the MN determines the indicator of the same candidate target SN.

[0013] According to some embodiments of the present application, the early data forwarding associated with the UE is an indirect early data forwarding for CHO with a target SCG.

[0014] In some embodiments of the present application, the information of route optimization indicates at least one of the following: an estimated arrival probability of the UE toward one of the one or more candidate target SNs prepared by the MN; or information of a shared data forwarding address, which indicates the number of candidate target MNs using the same data forwarding address of the one candidate target SN.

[0015] According to some embodiments of the present application, the early data forwarding associated with the UE is direct early data forwarding for CHO with multiple candidate SCGs.

[0016] In some embodiments of the present application, the information of route optimization indicates at least one of the following: an identifier of the one or more candidate target SNs; information of a shared data forwarding address, which indicates the number of candidate target MNs using the same data forwarding address of the one candidate target SN; one or more first estimated arrival probabilities, each first estimated arrival probability for the UE toward a corresponding candidate target SN in the one or more candidate target SNs prepared by the MN; or one or more second estimated arrival probabilities, each second estimated arrival probability for the UE toward a corresponding candidate target SN in the one or more candidate target SNs prepared by another candidate target MN different from the MN.

[0017] According to some embodiments of the present application, the second estimated arrival probability associated with the candidate target SN is received from the candidate target SN via an SN add request confirm message or an SN modify required message.

[0018] According to some embodiments of the present application, the transceiver is configured to: transmit to the candidate target SN information indicating a first time based on which a second estimated probability of arrival associated with the candidate target SN will be provided; and receive a message indicating the second estimated probability of arrival associated with the candidate target SN. In some scenarios, the transceiver is configured to: receive from the source MN information indicating a second time based on which the second estimated probability of arrival associated with the candidate target SN will be provided, wherein the first time is equal to or shorter than the second time.

[0019] According to some embodiments of the present application, the transceiver is configured to: receive a destination for data forwarding for an SN terminated bearer from the source MN, wherein the destination is an identifier of a target SN determined by the source MN.

[0020] According to some embodiments of the present application, the early data forwarding associated with the UE is an indirect early data forwarding for CHO with multiple candidate SCGs.

[0021] According to some embodiments of the present application, information related to the number of candidate target MNs using the same data forwarding address of the one candidate target SN is indicated via an SN Add Request Confirmation message or an SN Modification Request message. In some scenarios, the transceiver is configured to: transmit to the one candidate target SN information indicating a first time at which information related to the number of candidate target MNs using the same data forwarding address of the one candidate target SN will be provided; and receive information related to the number of candidate target MNs using the same data forwarding address of the one candidate target SN. In some scenarios, the transceiver is configured to: receive from the source MN information indicating a second time at which information related to a shared data forwarding address will be provided, wherein the first time is equal to or shorter than the second time. Example information related to the number of candidate target MNs using the same data forwarding address of the one candidate target SN is indicated by the one candidate target SN using a numerical value or at least an identifier of another candidate target MN other than the one MN that uses the same data forwarding address.

[0022] The exemplary first time is a time period or a time point. The exemplary second time is also a time period or a time point.

[0023] According to some embodiments of the present application, the time length is a waiting time, which indicates a maximum allowed waiting time for providing the information of the shared data forwarding address.

[0024] According to some embodiments of the present application, the time length is a waiting time, which indicates a maximum allowed waiting time for providing the second estimated arrival probability associated with the candidate target SN.

[0025] Some other embodiments of the present application provide another MN, such as a source MN, comprising: a processor; and a transceiver coupled to the processor and configured to: transmit a switching request for a CHO with a UE's SCG to a candidate target MN among one or more candidate target MNs; and receive from the candidate target MN information for route optimization of early data forwarding associated with at least one or more candidate target SNs prepared by the candidate target MN, wherein the early data forwarding is for the CHO with the SCG.

[0026] According to some embodiments of the present application, the information on route optimization for early data forwarding is received from the candidate target MN via a handover request confirmation message or a message later than the handover request confirmation message.

[0027] In some embodiments of the present application, the transceiver is configured to: transmit to the candidate target MN information indicating a time based on which information of a shared data forwarding address will be provided.

[0028] According to some embodiments of the present application, the information of the shared data forwarding address is received via a handover request confirmation message or a message later than the handover request confirmation message.

[0029] In some embodiments of the present application, the transceiver is configured to: transmit to the candidate target MN information indicating a time at which a second estimated probability of arrival associated with the corresponding candidate target SN will be provided.

[0030] In some embodiments of the present application, the processor is configured to: determine, based on route optimization information from the one or more candidate target MNs, that data will be forwarded to only one candidate target MN among the one or more candidate target MNs.

[0031] According to some embodiments of the present application, when more than one estimated arrival probability is received from more than one candidate target MN, the only one candidate target MN is the candidate target MN with the highest estimated arrival probability. In some scenarios, the processor is configured to: perform the early data forwarding to the only one candidate target MN; or indicate the only one candidate target MN to the source SN.

[0032] In some embodiments of the present application, the processor is configured to: determine, based on the route optimized information from the one or more candidate target MNs, that data is to be forwarded based on only one data forwarding address.

[0033] According to some embodiments of the present application, when more than one estimated arrival probability is received from more than one candidate target MN, the only one data forwarding address is the data forwarding address with the maximum estimated arrival probability. When data forwarding addresses are provided by different candidate target MNs with different estimated arrival probabilities, the estimated arrival probability of the data forwarding address is the average of the different estimated arrival probabilities.

[0034] According to some embodiments of the present application, in the case where information of a shared data forwarding address is received from more than one candidate target MN, the only one data forwarding address is the data forwarding address used by the largest number of candidate target MNs.

[0035] According to some embodiments of the present application, the processor is configured to: indicate the only one data forwarding address to the source SN.

[0036] In some embodiments of the present application, the processor is configured to: when the information of route optimization from more than one candidate target MN includes information about the identification of one or more candidate target SNs, determine the candidate target MN with the largest number of candidate target SNs as the only candidate target MN to which early data will be forwarded.

[0037] According to some embodiments of the present application, the processor is configured to: perform the early data forwarding to the only one candidate target MN; or indicate the only one candidate target MN to a source SN.

[0038] In some embodiments of the present application, the processor is configured to: when the information of route optimization from more than one candidate target MN includes information about one or more first estimated arrival probabilities, determine the candidate target SN with the maximum estimated arrival probability as the destination for data forwarding for SN termination bearer, wherein the maximum estimated arrival probability is the maximum first estimated arrival probability.

[0039] According to some embodiments of the present application, the processor is configured to: when the information of route optimization from more than one candidate target MN includes information about one or more second estimated arrival probabilities associated with the candidate target SN, the estimated arrival probability of the candidate target SN is the average of the first estimated arrival probability and different second estimated arrival probabilities from different candidate target MNs.

[0040] According to some embodiments of the present application, the transceiver is configured to: transmit the destination of data forwarding for the SN terminated bearer to the candidate target MN, wherein the destination is an identifier of the candidate target SN with the maximum estimated arrival probability. The processor is configured to: perform the early data forwarding to the candidate target MN for the SN terminated bearer and indicate the destination to the candidate target MN; or indicate the destination to a source SN.

[0041] Some embodiments of the present application provide an SN, such as a candidate target SN, comprising: a processor; and a transceiver coupled to the processor and configured to: receive first information about a CHO with an SCG of a UE from a candidate target MN; and transmit second information about route optimization for early data forwarding for the CHO with the SCG to the candidate target MN.

[0042] In some embodiments of the present application, the second information is transmitted via an SN add request confirm message or an SN modify request message.

[0043] In some embodiments of the present application, the second information indicates at least one of the following: an identifier of the SN; a random number allocated at the SN; or information indicating that the same data forwarding address is shared by other candidate target MNs and the candidate target MN.

[0044] In some embodiments of the present application, the second information indicates information related to the number of candidate target MNs using the same data forwarding address of the SN using a numerical value or at least using the identifiers of other candidate target MNs other than the candidate target MN that use the same data forwarding address of the SN.

[0045] According to some embodiments of the present application, the transceiver is configured to: receive information from the candidate target MN indicating a time based on which the information related to the number of candidate target MNs using the same data forwarding address of the SN will be provided; and determine information related to the number of candidate target MNs using the same data forwarding address based on the indicated time.

[0046] In some embodiments of the present application, the second information indicates at least one of the following: an identifier of the SN; information related to the number of candidate target MNs using the same data forwarding address of the SN; or one or more second estimated arrival probabilities, each second estimated arrival probability being for the UE toward the SN prepared by another candidate target MN different from the candidate target MN.

[0047] According to some embodiments of the present application, the transceiver is configured to: receive from the candidate target MN information indicating a time based on which the information related to the number of candidate target MNs using the same data forwarding address of the SN or at least one of the one or more second estimated arrival probabilities will be provided; and report to the candidate target MN based on the indicated time the information related to the number of candidate target MNs using the same data forwarding address of the SN or at least one of the one or more second estimated arrival probabilities.

[0048] In view of the above, embodiments of the present application provide a method and apparatus for supporting data forwarding, which can at least optimize early data forwarding for CHO with SCG and reduce resource abuse. Therefore, the present application can promote and improve the implementation of NR. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] In order to describe the manner in which the advantages and features of the present application can be obtained, the description of the present application is presented by reference to specific embodiments of the present application illustrated in the accompanying drawings. These drawings depict only example embodiments of the present application and therefore should not be considered limiting of its scope.

[0050] Figure 1A wireless communication system according to some embodiments of the present application is described.

[0051] Figure 2a An example scenario for indirect early data forwarding of a CHO with one target SCG is described.

[0052] Figure 2b An example scenario of indirect early data forwarding for CHO with multiple candidate SCGs is described.

[0053] Figure 2c An example scenario for direct early data forwarding of a CHO with one target SCG is described.

[0054] Figure 2d An example scenario for direct early data forwarding for CHO with multiple candidate SCGs is described.

[0055] Figure 3 is a flowchart of an exemplary process for supporting data forwarding in scenario 1 according to some embodiments of the present application.

[0056] Figure 4 is a flowchart of an exemplary process for supporting data forwarding in scenario 2 according to some embodiments of the present application.

[0057] Figure 5 is a flowchart of another exemplary process for supporting data forwarding in scenario 2 according to some other embodiments of the present application.

[0058] Figure 6 is a flowchart of an exemplary process for supporting data forwarding in scenario 3 according to some embodiments of the present application.

[0059] Figure 7 is a flowchart of another exemplary process for supporting data forwarding in scenario 3 according to some other embodiments of the present application.

[0060] Figure 8 A block diagram illustrating a device supporting data forwarding according to some embodiments of the present application.

[0061] Figure 9 A block diagram illustrating a device supporting data forwarding according to some other embodiments of the present application. DETAILED DESCRIPTION

[0062] The detailed description of the accompanying drawings is intended as a description of the preferred embodiments of the present application and is not intended to represent the only form in which the present application can be practiced. It should be understood that the same or equivalent functions can be achieved by different embodiments intended to be included in the spirit and scope of the present application.

[0063] Reference will now be made in detail to some embodiments of the present application, examples of which are illustrated in the accompanying drawings. To facilitate understanding, embodiments are provided in the context of specific network architectures and new service scenarios (e.g., 3GPP 5G, 3GPP LTE, etc.). It is contemplated that all embodiments in this application are also applicable to similar technical problems as network architectures and new service scenarios evolve. In addition, the terms described in this application may be changed without affecting the principles of this application.

[0064] In an NR-DC scenario, a UE with multiple transceivers can be configured to utilize resources provided by two different nodes connected via a non-ideal backhaul. One node can provide NR access and the other node can provide Evolved Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access (UTRA) (E-UTRA) or NR access. One node can act as a mobile node (MN) and the other node can act as a network node (SN). The MN and the SN are connected via a network interface (e.g., an Xn interface as specified in 3GPP standard documents), and at least the MN is connected to the core network (CN).

[0065] For example, Figure 1 A schematic diagram illustrating a wireless communication system 100 according to some embodiments of the present application.

[0066] like Figure 1 As shown in FIG, the wireless communication system 100 may be a dual connectivity system 100, including at least one UE 101, at least one MN 102, and at least one SN 103. Specifically, for illustrative purposes, Figure 1 The dual connectivity system 100 in FIG. 1 includes one shown UE 101, one shown MN 102, and one shown SN 103. Figure 1 A specific number of UEs 101, MNs 102, and SNs 103 are depicted in FIG. 1 , but it is contemplated that any number of UEs 101, MNs 102, and SNs 103 may be included in the wireless communication system 100.

[0067] refer to Figure 1 , UE 101 may be connected to MN 102 and SN 103 via an interface (e.g., a Uu interface as specified in 3GPP standard documents). MN 102 and SN 103 may be connected to each other via a network interface (e.g., an Xn interface as specified in 3GPP standard documents). MN 102 may be connected to SN 103 via a network interface (e.g., an Xn interface as specified in 3GPP standard documents). Figure 1 102 and SN 103). UE 101 is connected to the core network via a 3GPP interface (e.g., an NG interface as specified in 3GPP standard documents). UE 101 may be configured to utilize resources provided by MN 102 and SN 103 to perform data transmission.

[0068] In some embodiments of the present application, UE 101 may include a computing device such as a desktop computer, a laptop computer, a personal digital assistant (PDA), a tablet computer, a smart TV (e.g., a TV connected to the Internet), a set-top box, a game console, a security system (including a security camera), an in-vehicle computer, a network device (e.g., a router, a switch, and a modem), or the like. In some other embodiments of the present application, UE 101 may include a portable wireless communication device, a smartphone, a cellular phone, a flip phone, a device with a subscriber identity module, a personal computer, a selective call reception circuit system, or any other device capable of sending and receiving communication signals over a wireless network. In some other embodiments of the present application, UE 101 may include a wearable device such as a smart watch, a fitness band, an optical head-mounted display, or the like. Furthermore, UE 101 may be referred to as a subscriber unit, a mobile device, a mobile station, a user, a terminal, a mobile terminal, a wireless terminal, a fixed terminal, a subscriber station, a user terminal, or a device, or described using other terms used in the art.

[0069] MN 102 refers to a radio access network (RAN) node that provides a control plane connection to the core network. In an embodiment of the present application, in an E-UTRA-NR DC (EN-DC) scenario, MN 102 may be an eNB. In another embodiment of the present application, in a next-generation E-UTRA-NR DC (NGEN-DC) scenario, MN 102 may be a next-generation (ng)-eNB. In yet another embodiment of the present application, in an NR-DC scenario or an NR-E-UTRA DC (NE-DC) scenario, MN 102 may be a gNB. In some embodiments of the present application, MN 102 may also be referred to as a Master-NG-RAN (M-NG-RAN) node.

[0070] MCG may refer to a serving cell group associated with MN 102 and includes a primary cell (PCell) and optionally one or more SCells. The PCell may provide control plane connectivity to UE 101.

[0071] SN 103 may refer to a radio access network node that does not have a control plane connection to the core network but provides additional resources to UE 101. In some embodiments of the present application, in an EN-DC scenario, SN 103 may be an en-gNB. In some other embodiments of the present application, in an NR-DC scenario, SN 103 may be an ng-eNB. In yet another embodiment of the present application, in an NR-DC scenario or an NGEN-DC scenario, SN 103 may be a gNB. In some embodiments of the present application, SN 103 may also be referred to as a Secondary NG-RAN (S-NG-RAN) node.

[0072] An SCG may refer to a serving cell group associated with an SN and includes a PSCell and optionally one or more SCells. The PCell of an MCG and the PSCell of an SCG may also be referred to as a special cell (SpCell).

[0073] For CHO with an SCG, early data forwarding can be indirect or direct. In the case of indirect early data forwarding, the source MN or source SN forwards data to the candidate target MN, which then forwards the data to the candidate target SN. In the case of direct early data forwarding, the source MN or source SN forwards data directly to the candidate target SN without forwarding by the candidate target MN. Without data forwarding optimization, data will be sent via multiple paths, which will abuse network resources and may also cause other problems.

[0074] For example, for indirect early data forwarding for CHO with a target SCG, the source node (e.g., source MN) has a data forwarding address toward the candidate target MN, but does not have a data forwarding address toward the candidate target SN. Without data forwarding optimization, the source MN may send data to multiple candidate target MNs, and the data will be forwarded to the same candidate target SN through multiple candidate target MNs. In other words, data will be sent via multiple paths, which will abuse network resources. In addition, if multiplied data is received from multiple paths, the candidate target SN should remove the multiplied data from time to time, which requires high processing power and storage capacity.

[0075] For direct early data forwarding for CHO with multiple candidate SCGs, the source node (e.g., source MN) has a data forwarding address toward the candidate target SNs and sends data directly to the candidate target SNs. However, without data forwarding optimization, there are multiple paths for direct early data forwarding and data will also be sent via multiple paths.

[0076] For indirect early data forwarding for CHO with multiple candidate SCGs, the source node (e.g., source MN) has a data forwarding address toward the candidate target MN, but does not have a data forwarding address toward the candidate target SN. Therefore, the source MN will send data to the candidate target MN, and the data will be forwarded to multiple candidate target SNs via the candidate target MN. Therefore, the same candidate target SN can be prepared by multiple candidate target MNs and can receive multiplied data via multiple paths. In addition, the same candidate target MN can prepare multiple candidate target SNs and forward the same data to multiple candidate target SNs.

[0077] Figures 2a to 2d Four example scenarios for early data forwarding with CHO of SCG without data forwarding optimization are described, where Figure 2a An example scenario for indirect early data forwarding for a CHO with a target SCG is described; Figure 2b An example scenario of indirect early data forwarding for a CHO with multiple candidate SCGs is described; Figure 2c Describes an example scenario for direct early data forwarding of a CHO with a target SCG; and

[0078] Figure 2d An example scenario of direct early data forwarding for CHO with multiple candidate SCGs is illustrated. Dashed lines (eg, S1, S2, etc.) represent data forwarding paths.

[0079] refer to Figure 2a In an example scenario of indirect early data forwarding for CHO with one target SCG, there is only one candidate target SN (one target SN) and multiple (e.g., m>1) candidate target MNs. The candidate target SNs are prepared by candidate MN1, candidate MN2, ..., and candidate MNm. The source MN will forward data to candidate MN1 via S1, and then candidate MN1 will forward data to the candidate target SN via S5. Similarly, the source MN will forward data to candidate MN2 via S2, and then candidate MN2 will forward data to the candidate target SN via S7, and so on. The source MN will forward data to candidate MNm via Sm, and then candidate MNm will forward data to the candidate target SN via S9.

[0080] refer to Figure 2b In an exemplary scenario of indirect early data forwarding for CHO with multiple candidate SCGs, there are multiple (e.g., n>1) candidate target SNs and multiple (e.g., m>1) candidate target MNs. Each candidate target SN may be prepared by one or more candidate target MNs. For example, candidate target SN1 is prepared by candidate target MN1 and candidate target MN2, candidate target SN2 is prepared by candidate target MN1, candidate target MN2, and candidate target MNm... and candidate target SNn is prepared by candidate target MN2 and candidate target MNm. The source MN will forward data to candidate target MN1 via S1, and then candidate target MN1 will forward data to candidate target SN1 via S4 and to candidate target SN2 via S5. Similarly, the source MN will forward data to candidate target MN2 via S2, and then candidate target MN2 will forward data to candidate target SN1 via S6, to candidate target SN2 via S7, to candidate target SNn via S8, and so on. The source MN will forward the data to the candidate target MNm via Sm, and then the candidate target MNm will forward the data to the candidate target SN2 via S9 and to the candidate target SNn via S10.

[0081] and Figure 2a Similar, in Figure 2c In the example scenario of direct early data forwarding for CHO with one target SCG shown in FIG, there is only one candidate target SN (one target SN) and multiple (e.g., m>1) candidate target MNs. The candidate target SNs are prepared by candidate target MN1, candidate target MN2, ..., and candidate target MNm. The source MN will forward data directly to the candidate target SNs via S1.

[0082] and Figure 2b Similar, in Figure 2d In the example scenario of direct early data forwarding for CHO with multiple candidate target SCGs shown in FIG, there are multiple (e.g., n>1) candidate target SNs and multiple (e.g., m>1) candidate target MNs. Each candidate target SN may be prepared by one or more candidate target MNs. For example, candidate target SN1 is prepared by candidate target MN1 and candidate target MN2, candidate target SN2 is prepared by candidate target MN1, candidate target MN2, and candidate target MNm... and candidate target SNn is prepared by candidate target MN2 and candidate target MNm. The source MN will forward data directly to candidate target SN1 via S1, directly to candidate target SN2 via S2, and directly to candidate target SNn via SN.

[0083] Visible in Figure 2a 、 2b In 2d and 2d, there are multiple data forwarding paths for the same UE. Without data forwarding optimization, data will be sent via multiple paths, and the problems described above will occur. Similar problems will also occur when the source node is the source SN rather than the source MN.

[0084] At least in order to solve the above-mentioned problems regarding data forwarding for CHO with SCG, the embodiments of the present application provide technical solutions to support data forwarding, such as methods and devices to support data forwarding, which can at least optimize early data forwarding for CHO with SCG and reduce resource abuse in the network.

[0085] For example, some embodiments of the present application provide a method for supporting data forwarding, which can be performed by a candidate target MN (e.g., Figure 2a 、 2b 2d or similar). The method includes determining route optimization information (or route optimization information) for early data forwarding associated with at least one or more candidate target SNs prepared by the candidate target MN, wherein the early data forwarding is for a CHO with the SCG of the UE. The method also includes transmitting the route optimization information to the source MN, for example, via a handover request acknowledgement (ACK) message or other message.

[0086] Some other embodiments of the present application provide another method for supporting data forwarding, wherein the method may be performed by a source MN (eg, Figure 2a 、 2b 2d or the like). The method includes transmitting a handover request for CHO with the SCG of the UE to a candidate target MN of one or more candidate target MNs, for example, via a handover request message. The method also includes receiving, from the candidate target MN, for example, via a handover request ACK message or other message, information for route optimization for early data forwarding associated with at least one or more candidate target SNs prepared by the candidate target MN, wherein the early data forwarding is for CHO with the SCG.

[0087] In some scenarios (scenario 1), for example, where the early data forwarding associated with the UE is an indirect early data forwarding to a CHO with a target SCG or the like as shown in FIG. 2 , the route optimization information indicates at least one of: an identifier of one of the one or more candidate target SNs; a random number assigned at the one candidate target SN; or an indicator of the same candidate target SN, indicating that the data forwarding address associated with the early data forwarding will be mapped to the same data forwarding address of the one candidate target SN.

[0088] Regarding the data forwarding address (also referred to as data forwarding information), it can be a downlink (DL) data forwarding address or an uplink (UL) data forwarding address or both a DL and UL data forwarding address. An exemplary data forwarding address contains transport layer (TNL) information for establishing a data forwarding tunnel toward a target node (MN or SN). The TNL information corresponds to an Internet Protocol (IP) address and a General Packet Radio Service Tunneling Protocol (GTP) tunnel endpoint identifier (TEID). In addition, the data forwarding address is at least one of a protocol data unit (PDU) session or a DRB level, for example, at a PDU level, a DRB level, or a PDU and DRB level. When the data forwarding address is at a DRB level or a PDU and DRB level, it will include a DRB ID.

[0089] According to some embodiments of the present application, for simplicity, the data forwarding address associated with early data forwarding will be mapped to the same data forwarding address of the candidate target SN, indicating that the data forwarding address associated with early data forwarding will be mapped to the same candidate target SN. According to some embodiments of the present application, for simplicity, forwarding data to the same data forwarding address allocated by the candidate target SN indicates that data will be forwarded to the same candidate target SN.

[0090] Based on the information of route optimization, the source MN will know that data will be forwarded to the same candidate target SN, and will select (or determine) a candidate target MN for data forwarding. The candidate target MN can be randomly selected by the source MN or selected based on configured or predefined rules. For example, the information of route optimization can also indicate the estimated arrival probability of the UE towards the same candidate target SN prepared by the MN. The candidate target MN can provide the estimated arrival probability of the candidate target SN prepared by the candidate target MN. In the case where the candidate target SN is prepared by multiple candidate target MNs, each candidate target MN will have an estimated arrival probability of the candidate target SN, and the estimated arrival probabilities may be the same or different. When the source MN knows that data will be forwarded to the same candidate target SN and also receives data forwarding addresses from multiple candidate target MNs with different estimated arrival probabilities, the source MN can select the candidate target MN with the largest estimated arrival probability for data forwarding.

[0091] In some other scenarios (Scenario 2), for example, where the early data forwarding associated with the UE is for Figure 2d In the direct early data forwarding of CHO of multiple candidate SCGs or the like shown in the figure, the route optimization information indicates at least one of the following: an estimated arrival probability of the UE toward one candidate target SN prepared by the MN among the one or more candidate target SNs; or information of a shared data forwarding address indicating the number of candidate target MNs using the same data forwarding address of the one candidate target SN.

[0092] Based on the route optimization information received from multiple candidate target MNs, the source MN selects a candidate target SN for data forwarding. In some cases, the source MN may indicate a time to avoid contention based on information provided by the candidate target MNs or corresponding candidate target SNs about a shared data forwarding address. The candidate target MNs may also indicate similar times to the candidate target SNs independently or based on instructions from the source MN. For example, if a time is required, the T-SN will wait for the required time to count or determine the number of candidate target MNs using the same data forwarding address.

[0093] In some other scenarios (Scenario 3), for example, where the early data forwarding associated with the UE is for Figure 2bIn the indirect early data forwarding of the CHO of multiple candidate SCGs or the like shown in the embodiment, the route optimization information indicates at least one of the following: identification of one or more candidate target SNs; information of a shared data forwarding address indicating the number of candidate target MNs using the same data forwarding address of the one candidate target SN; one or more first estimated arrival probabilities, each first estimated arrival probability for the UE toward a corresponding candidate target SN in one or more candidate target SNs prepared by the MN; or one or more second estimated arrival probabilities, each second estimated arrival probability for the UE toward a corresponding candidate target SN in one or more candidate target SNs prepared by another candidate target MN different from the MN.

[0094] Based on the route optimization information received from multiple candidate target MNs, the source MN may determine the candidate target MN as the only candidate target MN to which early data will be forwarded, or may determine the candidate target SN as the destination for data forwarding for the SN terminated bearer. Similarly, it may be necessary to provide information about a shared data forwarding address and / or one or more second estimated arrival probabilities to avoid contention.

[0095] Some other embodiments of the present application provide yet another method for supporting data forwarding, which may be performed by a candidate target MN or the like. The method includes receiving first information regarding a CHO with a UE's SCG from the candidate target MN, for example, via an SN Add Request message. The method also includes transmitting second information regarding route optimization for early data forwarding for the CHO with the SCG to the candidate target MN, for example, via an SN Add Request ACK message or an SN Modify Request message. Based on the received second information, the candidate target MN may provide route optimization information to the source MN.

[0096] In some scenarios (scenario 1), for example, where the early data forwarding associated with the UE is an indirect early data forwarding for a CHO with a target SCG, the second information indicates at least one of: an identifier of the SN; a random number assigned at the SN; or information indicating that the same data forwarding address is shared by other candidate target MNs with the candidate target MN.

[0097] In some other scenarios (Scenario 2), for example, where the early data forwarding associated with the UE is direct early data forwarding for CHO with multiple candidate SCGs, the second information indicates information related to the number of candidate target MNs using the same data forwarding address of the SN, using a numerical value or at least the identifiers of other candidate target MNs other than the candidate target MN that use the same data forwarding address of the SN. The candidate target MN may determine or derive the number of candidate target MNs using the same data forwarding address based on the second information, or directly use the number of candidate target MNs indicated in the second information, and transmit information about the shared data forwarding address to the source MN. For example, the second information may directly indicate the number of candidate target MNs using the same data forwarding address, and the candidate target MN will directly indicate the same number as the information about the shared data forwarding address to the source MN. If the candidate target MN receives the identifiers of other candidate target MNs using the same data forwarding address (in some other cases, the second information may indicate the identifiers of all candidate target MNs using the same data forwarding address), the candidate target MN may determine the number of candidate target MNs using the same data forwarding address based on the identifiers of the other candidate target MNs (or all candidate target MNs) using the same data forwarding address. In some other cases, the candidate target MN may also directly use the identifier of at least other candidate target MN using the same data forwarding address indicated in the second information as information of the shared data forwarding address to the source MN, and the source MN will determine or derive the number of candidate target MNs using the same data forwarding address based on the indicated identifier.

[0098] In some other scenarios (scenario 3), for example, where the early data forwarding associated with the UE is an indirect early data forwarding for CHO with multiple candidate SCGs, the second information indicates at least one of: an identifier of the SN; information of a shared data forwarding address having a numerical value or having identifiers of other candidate target MNs that use the same data forwarding address of the SN other than the candidate target MN; or one or more second estimated arrival probabilities, each second estimated arrival probability being for the UE toward an SN prepared by another candidate target MN that is different from the candidate target MN.

[0099] The following describes more detailed embodiments of the present application based on some exemplary data forwarding scenarios. Those skilled in the art should understand that, although the exemplary embodiments describe the MN and SN in NR-DC, the described technical solutions can also be applied to similar RAN nodes and / or similar scenarios and should not be limited to specific devices and scenarios. Furthermore, although different exemplary embodiments are described with reference to different technical measures for clarity, based on the disclosure and teachings of this application, those skilled in the art may combine the described embodiments in various ways, although these are not specifically described.

[0100] Figure 3This is a flowchart of an exemplary process for supporting data forwarding in Scenario 1 according to some embodiments of the present application. Although multiple candidate target MNs exist, for the sake of simplicity and clarity, the operations of only one candidate target MN are described in detail. Given the disclosure and teachings of the specifically described candidate target MN, those skilled in the art will be familiar with the corresponding operations in other candidate target MNs. These operations may be the same, similar, or different from the operations of the described target MN due to the use of the same, similar, or different solutions taught by various embodiments of the present application.

[0101] refer to Figure 3 In step 301a, the source MN (for simplicity, also referred to as "S-MN") sends a message to the candidate target MN (for simplicity, also referred to as "T-MN") (for example, Figure 2a The Handover Request message or the like initiates the CHO process by sending a Handover Request message or the like to the candidate target MN 1 shown in FIG. The Handover Request message or the like includes the MCG configuration and, if the UE is configured with an SCG, the SCG configuration. The Handover Request message or the like also includes CHO-related information. The CHO-related information includes the S-MN identity (ID) and the UE ID allocated at the S-MN.

[0102] Similarly, in step 301b, the S-MN may also send a request to one or more other candidate target MNs (also referred to as “other T-MNs” for simplicity) (e.g., Figure 2a The T-MN2 or T-MNm shown in FIG. 1 sends a handover request message or the like to initiate the CHO handover procedure.

[0103] In step 303a, the T-MN sends an SN add request message or the like, including CHO-related information, to at least the candidate target SN prepared by the candidate target MN (also referred to as "T-SN" for simplicity). In some embodiments of the present application, in addition to the S-MN ID and the UE ID assigned to the S-MN, the CHO-related information may also include an estimated arrival probability of the UE toward the candidate target SN prepared by the candidate target MN.

[0104] In step 303b, other T-MNs may perform the same or similar operations.

[0105] In step 305a, the T-SN will reply with an SN Add Request Confirm message or the like. The SN Add Request Confirm message or the like includes a data forwarding address allocated by the T-SN, the data forwarding address being associated with the PDU session of the DRB configured with the SN terminated bearer option.

[0106] The T-SN may also provide the T-MN with route optimization related information in the same or similar message to assist the T-MN in determining route optimization information.

[0107] In some embodiments of the present application, the T-SN may indicate the identifier of the T-SN. An example identifier of the T-SN is the globally unique identifier of the T-SN. If multiple user planes (UPs) exist for the T-SN, the identifier of the T-SN will be a combination of the global node identifier of the candidate target SN and the UP identifier that uniquely identifies at least the UP within the candidate target SN.

[0108] In some other embodiments of the present application, the T-SN may indicate a random number to the T-MN. For example, based on the received S-MN ID and the UE ID assigned by the S-MN, the T-SN will know that the SN addition requests from multiple T-MNs are for the same UE. The T-SN may assign the same data forwarding address and the same random number to the UE, and then send the data forwarding address and random number to the T-MN.

[0109] In some other embodiments of the present application, after knowing that the SN add requests from multiple T-MNs are for the same UE, the T-SN may transmit to the T-MN information indicating that the same data forwarding address is also shared by other candidate target MNs.

[0110] The T-SN may transmit at least one of the above-mentioned contents in the route optimization related information to the T-MN, such as only the identifier of the T-SN, or only the random number, or only the information indicating that the same data forwarding address is also shared by other candidate target MNs, or any combination thereof.

[0111] If a similar message is received from other T-MNs in step 303b, the T-SN will reply a similar message to the other T-MNs in step 305b.

[0112] After receiving the SN Add Request ACK message, in step 307a, the T-MN transmits a Handover Request Acknowledge message or the like to the S-MN, which includes the data forwarding address allocated by the T-MN. The data forwarding address is associated with the PDU session of the DRB configured with the SN Terminated Bearer option.

[0113] The T-MN may also include route optimization information in the same message or in a different message. Based on information received from the T-SN, the route optimization information includes at least one of the following: a T-SN identifier; a random number assigned at the T-SN; or an indicator of the same candidate target SN. The indicator of the same candidate target SN (also referred to as the same candidate target SN indicator) indicates that the data forwarding address associated with early data forwarding will be mapped to the same data forwarding address assigned by the candidate target SN (for simplicity, also referred to as "the data forwarding address associated with early data forwarding will be mapped to the same candidate target SN"). In some embodiments of the present application, the indicator of the same candidate target SN is generated by the T-MN based on information indicating that the same data forwarding address is shared by other T-MNs with the T-MN. The example indicator of the same candidate target SN is an enumeration type. If the indicator of the same candidate target SN is set to true, it means that data will be forwarded to the same data forwarding address assigned by the T-SN (for simplicity, also referred to as "data will be forwarded to the same T-SN").

[0114] In some embodiments of the present application, in addition to indicating at least one of a T-SN identifier, a random number, and an indicator of the same candidate target SN to the S-MN, the route optimization information may further include an estimated arrival probability of the UE toward the T-SN prepared by the T-MN.

[0115] In step 307b, other T-MNs may transmit similar messages to the S-MN.

[0116] Based on the route optimization information, the S-MN will know that the data will be forwarded to the same T-SN and will select (or determine) a candidate target MN for data forwarding. In some cases, in step 309, the S-MN will perform early data forwarding to the selected candidate target MN (e.g., T-MN), and in step 311, the selected candidate target MN will forward the data to the T-SN. In some other cases, the S-MN will indicate the selected candidate target MN to the source SN, so that the source SN will perform data forwarding to the selected candidate target MN.

[0117] For example, if the T-SN identifiers received from multiple T-MNs are the same, then the S-MN will determine that the data will be forwarded to the same T-SN. Therefore, the S-MN will forward the data to the selected candidate target MN instead of other candidate target MNs. Figure 2a If the T-SN identifiers received by the candidate targets MN1, MN2 and MNm shown in FIG are the same, the S-MN will select only one of the candidate targets MN1, MN2 and MNm for data forwarding.

[0118] In the case that the random numbers assigned at the T-SN received from multiple T-MNs are the same, the S-MN will determine to forward the data to the same T-SN. Therefore, the S-MN will forward the data to the selected candidate target MN instead of other candidate target MNs. For example, if Figure 2a If the random numbers received by the candidate targets MN1, MN2 and MNm shown in FIG are the same, then the S-MN will select only one of the candidate targets MN1, MN2 and MNm for data forwarding.

[0119] In the case that the S-MN receives the same candidate target SN indicator from multiple T-MNs, the S-MN will determine that the data will be forwarded to the same T-SN. Therefore, the S-MN will forward the data to the selected candidate target MN instead of other candidate target MNs. For example, if Figure 2a If the candidate targets MN1, MN2 and MNm shown in FIG. 1 receive the same candidate target SN indicator, the S-MN will select only one of the candidate targets MN1, MN2 and MNm for data forwarding.

[0120] If the S-MN determines that data will be forwarded to the same T-SN and also receives estimated arrival probabilities toward the same T-SN from multiple T-MNs, the S-MN will select the candidate target MN with the highest estimated arrival probability for data forwarding. For example, if candidate target MN1 provides an estimated arrival probability of 90%, candidate target MN2 provides an estimated arrival probability of 80%, and candidate target MNm provides an estimated arrival probability of 70%, then the S-MN will select candidate target MN1 for data forwarding to the T-SN.

[0121] Figure 4 2 is a flowchart of an exemplary process for supporting data forwarding in Scenario 2 according to some embodiments of the present application. Although there are multiple candidate target MNs and multiple candidate target SNs, for the sake of simplicity and clarity, the operations of only one candidate target MN and at least one candidate target SN prepared by the candidate target MN are described in detail. Based on the disclosure and teachings of the specifically described candidate target MN and candidate target SN, those skilled in the art should be familiar with the corresponding operations in other candidate target MNs and candidate target SNs. Such operations may be the same, similar, or different from the operations of the described target MN due to the use of the same, similar, or different solutions taught by various embodiments of the present application.

[0122] refer to Figure 4 In step 401a, the S-MN sends a message to the T-MN (e.g. Figure 2dThe Handover Request message or the like initiates the CHO process by sending a Handover Request message or the like to the candidate target MN 1 shown in FIG. The Handover Request message or the like includes the MCG configuration and, if the UE is configured with an SCG, the SCG configuration. The Handover Request message or the like also includes CHO-related information. The CHO-related information includes the S-MN ID and the UE ID assigned at the S-MN.

[0123] Similarly, in step 401b, the S-MN may also send a message to one or more other T-MNs (e.g., Figure 2d The candidate target MN2 or the candidate target MNm shown in FIG. 1 sends a handover request message or the like to initiate the CHO handover process.

[0124] In step 403a1, the T-MN sends an SN Add Request message or the like to a candidate target SN (also referred to as "T-SN" for simplicity), including CHO-related information. In some embodiments of the present application, in addition to the S-MN ID and the UE ID assigned at the S-MN, the CHO-related information may also include an estimated arrival probability of the UE toward the candidate target SN prepared by the T-MN.

[0125] In step 403a2, the T-MN may also send the same message to other candidate target SNs (also referred to as "other T-SNs" for simplicity). Other T-MNs may perform the same or similar operations as the T-SN in step 403b1 and in step 403b2.

[0126] In step 405a1, the T-SN will reply with an SN Add Request Confirm message or the like. The SN Add Request Confirm message or the like includes a data forwarding address allocated by the T-SN, the data forwarding address being associated with the PDU session of the DRB configured with the SN terminated bearer option.

[0127] The T-SN may also provide the T-MN with information related to route optimization in the same or similar message to assist the T-MN in determining information for route optimization.

[0128] Because a data forwarding address is allocated to each T-MN by the T-SN, and the T-SN can obtain the number of T-MNs that share the data forwarding address, in some embodiments of the present application, the T-SN may indicate information related to the number of candidate target MNs using the same data forwarding address of the T-SN, allowing the T-MN to determine information about the shared data forwarding address. Information related to the number of candidate target MNs using the same data forwarding address of the T-SN may be explicitly indicated using a numerical value (e.g., 3), or at least implicitly indicated using the identifiers of other T-MNs using the same data forwarding address of the T-SN.

[0129] In some cases, the T-MN may indicate a first time (e.g., included in an SN add request message or the like in step 403a1) at which information related to the number of candidate target MNs using the same data forwarding address of the T-SN will be provided. An exemplary first time is a time duration or a point in time. For example, the time duration may be a waiting time indicating a maximum allowable waiting time for the T-SN to provide the number of candidate target MNs using the same data forwarding address of the T-SN. The T-SN will determine information related to the number of candidate target MNs using the same data forwarding address based on the indicated time, for example, counting the number of candidate target MNs using the same data forwarding address only at the indicated point in time, or counting the number of candidate target MNs using the same data forwarding address only at a first time determined based on the time duration or within the first time.

[0130] In some embodiments of the present application, the T-MN may receive information indicating a second time based on information (e.g., included in the handover request message in step 401a or the like) indicating that the shared data forwarding address will be provided from the S-MN. Similarly, the second time is a time period or a point in time. An example time period may be a waiting time indicating the maximum allowable waiting time for the T-MN to provide candidate target MNs using the same data forwarding address of the T-SN. The T-MN will ensure that the first time is equal to or shorter than the second time.

[0131] In the case of indicating the first time, it is assumed that after obtaining the information related to the number of candidate target MNs using the same data forwarding address of the T-SN based on the first time, in step 405a1, the T-SN will reply with an SN add request confirm message or the like, so that in step 405a1, the T-SN can indicate the information related to the number of candidate target MNs using the same data forwarding address of the T-SN in the SN add request confirm message or the like.

[0132] If the T-SN receives a similar message from another T-MN in step 403b1, the T-SN will reply with a similar message to the other T-MN in step 405b1. If the other T-SN receives a similar message from the T-MN and another T-MN in steps 403a2 and 403b2, the other T-SN will reply with a similar message to the T-MN in step 405a2 and to the other T-MN in step 405b2.

[0133] After receiving the SN Add Request Confirm message from the T-SN, the T-MN transmits a Handover Request Confirm message or the like to the S-MN in step 407a, which includes the data forwarding address allocated by the T-SN. The data forwarding address is associated with the PDU session of the DRB configured with the SN terminated bearer option.

[0134] The T-MN may also include route optimization information in the same message or in a different message. Based on information received from the T-SN, the route optimization information includes at least one of the following: an estimated probability of the UE arriving toward the T-SN prepared by the T-MN; or information about a shared data forwarding address indicating the number of candidate target MNs using the same data forwarding address of the T-SN.

[0135] In step 407b, other T-MNs will transmit similar messages to the S-MN.

[0136] Based on the route optimization information, the S-MN selects (or determines) a data forwarding address (or a candidate target SN) for data forwarding. In step 409, the source MN performs early data forwarding to a selected candidate target SN (e.g., a T-SN) based on the selected data forwarding address; or indicates the selected candidate target SN to the source SN, causing the source SN to perform data forwarding to the selected candidate target SN.

[0137] For example, if the S-MN receives different data forwarding addresses from multiple T-MNs with different estimated arrival probabilities, the S-MN will select the data forwarding address sent from the T-MN with the highest estimated arrival probability for data forwarding. Figure 2d As shown in FIG, candidate target MN1 provides data forwarding address 1 toward SN1 with an estimated arrival probability of 90%, candidate target MN2 provides data forwarding address 2 toward SN2 with an estimated arrival probability of 50%, and candidate target MNm provides data forwarding address n toward candidate target SNn with an estimated arrival probability of 80%. Then, the S-MN will select data forwarding address 1 for data forwarding. Data will be sent directly from the S-MN or the source SN to candidate target SN1.

[0138] In some cases, the same T-SN may be prepared by multiple T-MNs, for example, candidate target SN1 may be prepared by candidate target MN1 and candidate target MN2. When an S-MN receives the same data forwarding address from multiple T-MNs with different estimated arrival probabilities, the S-MN may further process the received estimated arrival probabilities associated with the T-SNs, such as by averaging the received estimated arrival probabilities. For example, if, for the same data forwarding address (e.g., the data forwarding address of candidate target SN1), candidate target MN1 provides an estimated arrival probability of 80%, while candidate target MN2 provides an estimated arrival probability of 60%, the S-MN will deduce or determine that the estimated arrival probability of the UE toward candidate target SN1 is 70%.

[0139] In case of receiving information of a shared data forwarding address from more than one T-MN, the S-MN may select a data forwarding address used by the largest number of candidate target MNs for data forwarding or by the largest number of shared data forwarding addresses. Figure 2d As shown in FIG, the number of candidate target MNs that provide shared data forwarding address 1 to candidate target SN1 is 5, and the number of candidate target MNs that provide shared data forwarding address 2 to candidate target SN2 is 2, then the source MN may select data forwarding address 1 for data forwarding.

[0140] In case both the information on the estimated arrival probability and the information of the shared data forwarding address are received from more than one candidate target MN, the S-MN will select the data forwarding address based on its own implementation in various ways.

[0141] Figure 5 is a flowchart of another exemplary process for supporting data forwarding in scenario 2 according to some other embodiments of the present application. Similarly, although there are multiple candidate target MNs and multiple candidate target SNs, for the sake of simplicity and clarity, the operations of only one candidate target MN and at least one candidate target SN prepared by the candidate target MN are illustrated in detail. Based on the disclosure and teachings of the specifically described candidate target MN and candidate target SN, those skilled in the art should be familiar with the corresponding operations in other candidate target MNs and candidate target SNs, which may be the same, similar, or different from the operations of the described target MN due to the use of the same, similar, or different solutions taught by various embodiments of the present application.

[0142] and Figure 4 In comparison, Figure 5 The difference is that route optimization related information is transmitted to the T-MN in an SN Modification Request message or the like, rather than in an SN Add Request ACK message. Steps 501a to 503b2 are the same as steps 401a to 403b2; and steps 505a1 to 505b2 can also refer to steps 405a1 to 405b2, wherein only the conventional SN Add Request ACK message is sent, and route optimization related information is not transmitted to the T-MN.

[0143] In step 507a, the T-MN may simply reply with a Handover Request ACK message or include route optimization information indicating the estimated arrival probability of the UE toward the T-SN prepared by the T-MN in the Handover Request ACK message. Step 507b is similar. If route optimization information indicating the estimated arrival probability is received, the S-MN may perform route optimization based on the received estimated arrival probability as described above, or wait for further route optimization information.

[0144] In step 509a1, the T-SN transmits a message indicating information related to the number of candidate target MNs using the same data forwarding address of the SN to the T-MN, for example, through an SN modification request message or the like (which may be a numerical value (e.g., 3) or the identifiers of other T-MNs using the same data forwarding address of the T-SN or the identifiers of all T-MNs using the same data forwarding address of the T-SN, etc.). Steps 509a2 to 509b2 are similar.

[0145] In some cases, the T-MN may indicate a first time based on information regarding the number of candidate target MNs using the same data forwarding address of the SN to be provided (e.g., included in the SN Add Request message in step 503a1 or the like). The T-SN determines information regarding the number of candidate target MNs using the same data forwarding address based on the indicated time. If the T-MN receives a second time based on information regarding the shared data forwarding address to be provided from the S-MN (e.g., included in the Handover Request message in step 501a), the first time will be equal to or shorter than the second time.

[0146] After receiving the information about the number of candidate target MNs using the same data forwarding address indicated by the T-SN, in step 511a, the T-MN transmits route optimization information including information about the shared data forwarding address to the S-MN, for example, via a message following the handover request ACK message. In some embodiments of the present application, in step 507a, the T-MN may not transmit any route optimization information to the S-MN, and may transmit the route optimization information to the S-MN as shown in FIG. Figure 4 The route optimization information is transmitted to the source MN as described in step 407a described in , wherein the route optimization information includes at least one of the estimated arrival probability of the UE toward the T-SN prepared by the T-MN or information of the shared data forwarding address.

[0147] In step 511b, other T-MNs will transmit similar messages to the S-MN.

[0148] and Figure 4 Similarly, based on the route optimization information, the S-MN selects (or determines) a data forwarding address (or a candidate target SN) for data forwarding. In step 513, the source MN performs early data forwarding to a selected SN (e.g., T-SN) based on the selected data forwarding address; or indicates the selected candidate target SN to the source SN, causing the source SN to perform data forwarding to the selected candidate target SN.

[0149] Figure 63 is a flowchart of an exemplary process for supporting data forwarding in scenario 3 according to some embodiments of the present application. Similarly, although there are multiple candidate target MNs and multiple candidate target SNs, for the sake of simplicity and clarity, the operations of only one candidate target MN and at least one candidate target SN prepared by the candidate target MN are illustrated in detail. Based on the disclosure and teachings of the specifically described candidate target MN and candidate target SN, those skilled in the art should be familiar with the corresponding operations in other candidate target MNs and candidate target SNs, which may be the same, similar, or different from the operations of the described target MN due to the use of the same, similar, or different solutions taught by various embodiments of the present application.

[0150] refer to Figure 6 In step 601a, the S-MN sends a message to the T-MN (e.g. Figure 2b The Handover Request message or the like initiates the CHO process by sending a Handover Request message or the like to the candidate target MN 1 shown in FIG. The Handover Request message or the like includes the MCG configuration and, if the UE is configured with an SCG, the SCG configuration. The Handover Request message or the like also includes CHO-related information. The CHO-related information includes the S-MN ID and the UE ID assigned at the S-MN.

[0151] Similarly, in step 601b, the S-MN may also send a message to one or more other T-MNs (e.g., Figure 2b The candidate target MN2 or the candidate target MNm shown in FIG. 1 sends a handover request message or the like to initiate the CHO handover process.

[0152] In some cases, the S-MN may further indicate to the T-MN a time (second time) for determining routing optimization information based on information such as the shared data forwarding address and / or one or more second estimated arrival probabilities. For example, the second time is a waiting time length that indicates a maximum allowable waiting time for providing information about the shared data forwarding address and / or a maximum allowable waiting time for providing the second estimated arrival probabilities.

[0153] In step 603a1, the T-MN transmits an SN Add Request message or the like to the T-SN, including CHO-related information. In some embodiments of the present application, in addition to the S-MN ID and the UE ID assigned at the S-MN, the CHO-related information may also include an estimated arrival probability of the UE toward the target SN prepared by the T-MN.

[0154] In some cases, the T-MN may also indicate to the T-SN a time (first time) at which route optimization-related information will be determined based on information related to the number of candidate target MNs using the same data forwarding address of the T-SN and / or one or more second estimated arrival probabilities. If the S-MN provides the second time, the first time may be shorter or later than the first time. In other cases, the S-MN may directly indicate the first time at which route optimization-related information will be determined.

[0155] In step 603a2, the T-MN may also transmit the same message to other T-SNs. Other T-MNs may perform the same or similar operations as the T-SN in step 603b1 and as other T-SNs in step 603b2.

[0156] In step 605a1, the T-SN will reply with an SN Add Request Confirm message or the like. The SN Add Request Confirm message or the like includes a data forwarding address allocated by the T-SN, the data forwarding address being associated with the PDU session of the DRB configured with the SN terminated bearer option.

[0157] Similarly, the T-SN may also provide the T-MN with information related to route optimization in the same or similar message to assist the T-MN in determining information for route optimization.

[0158] For example, with Figure 3 Similarly, in some embodiments of the present application, T-SN may indicate an identifier of the T-SN. An example identifier of the T-SN is a globally unique identifier of the T-SN.

[0159] and Figure 4 Similarly, in some embodiments of the present application, the T-SN may explicitly indicate information related to the number of candidate target MNs using the same data forwarding address as the T-SN using a numerical value (e.g., 3), or at least implicitly indicate information related to the number of candidate target MNs using the same data forwarding address using identifiers of other T-MNs using the same data forwarding address as the T-SN. When the first time is provided, the T-SN will determine the number of candidate target MNs using the same data forwarding address based on the first time.

[0160] In some cases, the T-SN may indicate to the T-MN the estimated arrival probabilities from other T-MNs (second estimated arrival probabilities). Each second estimated arrival probability is the estimated arrival probability of the UE toward the T-SN prepared by another candidate target MN. For example, if Figure 2bAs shown in FIG, candidate SN2 is also prepared by candidate MN2 and candidate MNm in addition to candidate MN1. In this case, candidate SN2 will provide a second estimated probability of arrival to candidate MN1, including the estimated probability of arrival from candidate MN2 and the estimated probability of arrival from candidate MNm. When the first time is provided, the T-SN will determine the second estimated probability of arrival from the other T-MNs based on the first time.

[0161] In addition, Figure 6 In the case of indicating the first time, it is assumed that after obtaining information related to the number of candidate target MNs using the same data forwarding address and / or one or more second estimated arrival probabilities based on the first time, the T-SN will reply with an SN Add Request Confirmation message or the like in step 605a1. Therefore, in step 405a1, the T-SN may indicate information related to the number of candidate target MNs using the same data forwarding address and / or one or more second estimated arrival probabilities in the SN Add Request Confirmation message or the like.

[0162] The T-SN may transmit at least one of the above-mentioned route optimization related information to the T-MN, such as only the identifier of the T-SN, or only information related to the number of candidate target MNs using the same data forwarding address, or only one or more second estimated arrival probabilities, or any combination thereof.

[0163] If the T-SN receives a similar message from another T-MN in step 603b1, the T-SN will reply with a similar message to the other T-MN in step 605b1. If the other T-SN receives a similar message from the T-MN and another T-MN in steps 603a2 and 603b2, the other T-SN will reply with a similar message to the T-MN in step 605a2 and to the other T-MN in step 605b2.

[0164] After receiving the SN Add Request Confirm message or the like from the T-SN, the T-MN transmits a Handover Request Confirm message or the like to the S-MN in step 607a, which includes the data forwarding address allocated by the T-MN. The data forwarding address is associated with the PDU session of the DRB configured with the SN Terminated Bearer option.

[0165] The T-MN may also include route optimization information in the same message or a different message. Based on the information received from the T-SN, the route optimization information includes at least: identifications of one or more candidate target SNs, such as a list of T-SN identifications prepared by the T-MN. The route optimization information may further include at least one of the following: information on a shared data forwarding address, which indicates the number of candidate target MNs using the same data forwarding address of one candidate target SN; one or more first estimated arrival probabilities, each first estimated arrival probability for the UE toward a corresponding candidate target SN in one or more candidate target SNs prepared by the T-MN; or one or more second estimated arrival probabilities, each second estimated arrival probability for the UE toward a corresponding candidate target SN in one or more candidate target SNs prepared by another candidate target MN different from the T-MN.

[0166] Table 1 below illustrates exemplary route optimization information, for example, from T-MN1. The exemplary information indicates the identities of T-SNs prepared by the T-MN, such as T-SN1 and T-SN2 prepared by T-MN1. For each T-SN, Table 1 further indicates the estimated probability of a UE arriving at the T-SN prepared by the T-MN (a first estimated probability of arrival) and the estimated probability of the UE arriving at T-SNs prepared by other T-MNs (a second estimated probability of arrival) (or, the estimated probability of the UE arriving at a T-SN from another T-MN). Taking T-SN2 as an example, the first estimated probability of arrival from T-MN1 and the second estimated probability of arrival from T-MN4 are indicated.

[0167] Table 1

[0168]

[0169] In step 607b, other T-MNs will transmit similar messages to the S-MN.

[0170] Based on the route optimization information, the S-MN will perform route optimization for data forwarding, such as selecting a candidate target MN for data forwarding and optionally further determining a destination for data forwarding of SN terminated bearers, wherein the destination is the identity of the selected T-SN.

[0171] When an S-MN receives data forwarding addresses and T-SN identifiers (e.g., multiple T-SN identifier lists) from multiple T-MNs, the S-MN may determine the T-MN for data forwarding based on the received T-SN identifier lists. In some embodiments of the present application, the S-MN selects the T-MN with the largest number of shared T-SNs. For example, assuming that T-MN1 provides data forwarding addresses for T-SN1, T-SN2, and T-SN3, T-MN2 provides data forwarding addresses for T-SN2, T-SN3, and T-SN4, and T-MN3 provides data forwarding addresses for T-SN3 and T-SN4, the S-MN selects T-MN2 for data forwarding because T-MN2 has the largest number of shared T-SNs. In some other embodiments of the present application, the S-MN may select the T-MN with the largest number of T-SNs as the candidate target MN for data forwarding. The S-MN may employ further approaches based on its implementation.

[0172] When the estimated arrival probability (first estimated arrival probability and / or second estimated arrival probability) of the UE toward the T-SN prepared by the T-MN is included in the route optimization information, the S-MN may select the T-SN with the maximum estimated arrival probability for data forwarding.

[0173] For example, if Figure 2b As shown in FIG, the first estimated arrival probability toward candidate SN1 is 90% and the first estimated arrival probability toward candidate SN2 is 70%, the S-MN selects candidate SN1 as the destination for data forwarding. In step 609, destination notification is performed, in which the S-MN notifies the selected T-MN of the data forwarding destination. If the source SN is to perform data forwarding, the S-MN also indicates the data forwarding destination to the source SN.

[0174] If the estimated arrival probability (second estimated arrival probability) toward a T-SN prepared by another T-MN is included in the route optimization information, the S-MN may process the estimated arrival probabilities associated with the same T-SN, for example, by averaging the first and second estimated arrival probabilities for the T-SN. For example, for candidate target SN1, the estimated arrival probability from candidate target MN1 is 90%, and the estimated arrival probability from candidate target MN2 is 50%. For candidate target SN2, the estimated arrival probability from candidate target MN1 is 90%, the estimated arrival probability from candidate target MN2 is 80%, and the estimated arrival probability from candidate target MNm is 70%. In this case, the S-MN will conclude that the estimated arrival probability toward candidate target SN1 is 70%, and the estimated arrival probability toward T-SN2 is 80%, and the S-MN will then select candidate target SN2 as the destination for data forwarding.

[0175] The source MN will perform early data forwarding to the selected one T-MN; or indicate the selected candidate target MN to the source SN, so that the source SN will perform data forwarding to the selected candidate target MN.

[0176] In the case where the route optimization information indicates information of a shared data forwarding address, the S-MN may communicate with Figure 4 The T-SN is selected in a manner similar to that described in .

[0177] In addition, in case the route optimization information indicates various types of information as explained above, the S-MN will perform route optimization in various ways based on its implementation.

[0178] After optimizing the route for data forwarding, the S-MN or source SN will perform data forwarding based on the optimized route, eg, will forward data only to the selected T-MN and then to the forwarding destination.

[0179] Figure 7 3 is a flowchart of another exemplary process for supporting data forwarding in scenario 3 according to some other embodiments of the present application. Similarly, although there are multiple candidate target MNs and multiple candidate target SNs, for the sake of simplicity and clarity, the operations of only one candidate target MN and at least one candidate target SN prepared by the candidate target MN are illustrated in detail. Based on the disclosure and teachings of the specifically described candidate target MN and candidate target SN, those skilled in the art should be familiar with the corresponding operations in other candidate target MNs and candidate target SNs, which may be the same, similar, or different from the operations of the described target MN due to the use of the same, similar, or different solutions taught by various embodiments of the present application.

[0180] and Figure 6 In comparison, Figure 7 The difference is that all route optimization related information is transmitted to the T-MN in the SN Modification Request message instead of the SN Add Request ACK message. Steps 701a to 703b2 are the same as steps 601a to 603b2; and steps 705a1 to 705b2 can also refer to steps 605a1 to 605b2, wherein only the traditional SN Add Request ACK message is sent, and no route optimization related information or only part of it, such as the T-SN identifier, is transmitted to the T-MN.

[0181] In step 707a, the T-MN may reply with only a Handover Request ACK message, or include route optimization information in the Handover Request ACK message. The route optimization information at least indicates the identifier of the T-SN prepared by the T-MN. The route optimization information may further include an estimated arrival probability (first estimated arrival probability) of the UE toward each T-SN prepared by the T-MN. The process is similar in step 707b.

[0182] Upon receiving route optimized information indicating the identity of the T-SN and optionally the first estimated probability of arrival, the S-MN may perform route optimization based on the received route optimization information as explained above, or wait for further route optimization information.

[0183] In step 709a1, the T-SN transmits at least one of information related to the number of candidate target MNs using the same data forwarding address or one or more second estimated arrival probabilities to the T-MN, for example, via an SN modification request message or the like. The same is true in steps 709a2 to 709b2.

[0184] In some cases, the T-MN may indicate a first time based on information regarding the number of candidate target MNs using the same data forwarding address of the SN (e.g., included in the SN Add Request message in step 703a1 or the like). The T-SN determines the number of candidate target MNs using the same data forwarding address based on the indicated time. If the T-MN receives a second time based on information regarding the shared data forwarding address to be provided from the S-MN (e.g., included in the Handover Request message in step 701a), the first time will be equal to or shorter than the second time.

[0185] Similarly, in some cases, the T-MN may indicate a first time based on which one or more second estimated arrival probabilities will be provided (e.g., included in an SN add request message in step 703a1 or the like). The T-SN will determine one or more second estimated arrival probabilities based on the indicated time. If the second time is based on the one or more second estimated arrival probabilities provided by the S-MN (e.g., included in the handover request message in step 701a), the first time will be equal to or shorter than the second time.

[0186] After receiving route optimization related information (e.g., information indicating the number of candidate target MNs using the same data forwarding address or at least one of the one or more second estimated arrival probabilities) from the T-SN based on the indicated time, in step 711a, the T-MN transmits route optimization information including information about the shared data forwarding address and / or the one or more second estimated arrival probabilities to the S-MN, for example, via a message following the handover request ACK message. In some embodiments of the present application, in step 707a, the T-MN may not transmit any route optimization information to the S-MN, and transmits route optimization information including at least one of the following: an identifier of the T-SN prepared by the T-MN; the first estimated arrival probability of the T-SN; information about the shared data forwarding address; or the second estimated arrival probability of the T-SN, as described in step 607a.

[0187] In step 711b, other T-MNs will transmit similar messages to the S-MN.

[0188] and Figure 6 Similarly, based on the route optimization information, the S-MN will select (or determine) a candidate target MN for data forwarding or determine the destination for the SN to terminate the bearer. In the case of determining the destination, the S-MN will notify the T-MN of the destination or indicate the destination to the source SN in step 713 before forwarding the data.

[0189] In addition to the method, the embodiment of the present application also proposes a device that supports data forwarding. For example, Figure 8 is a block diagram of a device supporting data forwarding according to some embodiments of the present application.

[0190] like Figure 8 As shown in FIG, an apparatus 800 may include at least one non-transitory computer-readable medium 801, at least one receive circuitry 802, at least one transmit circuitry 804, and at least one processor 806 coupled to the non-transitory computer-readable medium 801, the receive circuitry 802, and the transmit circuitry 804. The apparatus 800 may be a RAN node (e.g., a MN or SN) configured to perform the method described above or the like.

[0191] Although elements such as at least one processor 806, transmit circuitry 804, and receive circuitry 802 are described in the singular in this figure, the plural is contemplated unless limitation to the singular is explicitly stated. In some embodiments of the present application, receive circuitry 802 and transmit circuitry 804 may be combined into a single device, such as a transceiver. Processor 806 may be a central processing unit (CPU), a digital signaling processor (DSP), a microprocessor, or the like. In certain embodiments of the present application, apparatus 800 may further include an input device, a memory, and / or other components.

[0192] In some embodiments of the present application, a non-transitory computer-readable medium 801 may store thereon computer-executable instructions for causing a processor 806 to implement a method related to a RAN node (e.g., a MN or SN as described above). For example, when the computer-executable instructions are executed, the processor 806 interacts with the receiving circuitry 802 and the transmitting circuitry 804 to perform the steps described above related to the RAN node.

[0193] Figure 9 A block diagram illustrating a device 700 supporting data forwarding according to some other embodiments of the present application.

[0194] refer to Figure 9, apparatus 900 (e.g., MN or SN) may include at least one processor 902 and at least one transceiver 904. Transceiver 904 may include at least one separate receive circuitry 906 and transmit circuitry 908, or at least one integrated receive circuitry 906 and transmit circuitry 908. At least one processor 902 may be a CPU, a DSP, a microprocessor, or the like.

[0195] According to some embodiments of the present application, when the device 900 is an MN (e.g., a candidate target MN), the processor is configured to: determine route optimization information for early data forwarding associated with at least one or more candidate target SNs prepared by the MN, wherein the early data forwarding is for CHO with the UE and the SCG; and a transceiver, coupled to the processor and configured to: transmit the route optimization information to the source MN.

[0196] According to some other embodiments of the present application, when the device 900 is an MN (e.g., a source MN), the processor may be configured to: transmit a switching request for a CHO with the SCG of the UE to a candidate target MN among one or more candidate target MNs; and receive information from the candidate target MN for route optimization for early data forwarding associated with at least one or more candidate target SNs prepared by the candidate target MN, wherein the early data forwarding is for a CHO with the SCG.

[0197] According to some other embodiments of the present application, when the device 900 is an SN (e.g., a candidate target SN), the processor may be configured to: receive first information about the CHO with the SCG of the UE from the candidate target MN; and transmit second information about route optimization for early data forwarding for the CHO with the SCG to the candidate target MN.

[0198] The method according to the embodiment of the present application can also be implemented on a programmed processor. However, the controller, flow chart and module can also be implemented on a general or special-purpose computer, a programmed microprocessor or microcontroller and peripheral integrated circuit components, an integrated circuit, a hardware electronic or logic circuit (such as a discrete element circuit), a programmable logic device or the like. In general, any device capable of implementing the flow chart shown in the figure can be used to implement the processor function of the present application. For example, an embodiment of the present application provides a device comprising a processor and a memory. Computer programmable instructions for implementing the method are stored in a memory, and the processor is configured to execute the computer programmable instructions to implement the method. The method may be the method stated above or other methods according to the embodiment of the present application.

[0199] Alternative embodiments preferably implement the methods according to embodiments of the present application in a non-transitory computer-readable storage medium storing computer programmable instructions. The instructions are preferably executed by a computer-executable component that is preferably integrated with a network security system. The non-transitory computer-readable storage medium may be stored on any suitable computer-readable medium, such as a random access memory (RAM), a read-only memory (ROM), a flash memory, an electrically erasable programmable read-only memory (EEPROM), an optical storage device (a compact disc (CD) or a digital video disc (DVD)), a hard drive, a floppy disk drive, or any suitable device. The computer-executable component is preferably a processor, but the instructions may alternatively or additionally be executed by any suitable dedicated hardware device. For example, an embodiment of the present disclosure provides a non-transitory computer-readable storage medium having computer programmable instructions stored therein. The computer programmable instructions are configured to implement the methods set forth above or other methods according to embodiments of the present application.

[0200] Although the present application has been described using specific embodiments thereof, it is apparent that many alternatives, modifications, and variations may be apparent to those skilled in the art. For example, various components of the described embodiments may be interchanged, added, or replaced in other embodiments. Moreover, not all elements of each figure are necessary for the operation of the disclosed embodiments. For example, it will enable one of ordinary skill in the art of the disclosed embodiments to make and use the teachings of the present application by simply adopting the elements of the independent claims. Therefore, the embodiments of the present application as described herein are intended to be illustrative and not restrictive. Various changes may be made without departing from the spirit and scope of the present application.

Claims

1. A master node MN, comprising: A processor configured to: determining information for route optimization for early data forwarding associated with at least one or more candidate target secondary nodes SN prepared by the MN, wherein the early data forwarding is for a conditional handover CHO with a secondary cell group SCG of a user equipment UE; and a transceiver coupled to the processor and configured to: The information of route optimization is transmitted to the source MN.

2. The MN according to claim 1, wherein the information of route optimization indicates at least one of the following: an identifier of a candidate target SN among the one or more candidate target SNs; a random number assigned at said one candidate target SN; or An indicator of the same candidate target SN, indicating that the data forwarding address associated with the early data forwarding is to be mapped to the same data forwarding address of the one candidate target SN.

3. The MN according to claim 2, wherein the information of route optimization further indicates an estimated arrival probability of the UE toward the one candidate target SN prepared by the MN.

4. The MN of claim 2, wherein the transceiver is configured to: Information indicating that the same data forwarding address is shared by other candidate target MNs and the MN is received, so that the indicator of the same candidate target SN is determined by the MN.

5. The MN according to claim 1, wherein the information of route optimization indicates at least one of the following: An estimated arrival probability of the UE towards a candidate target SN among the one or more candidate target SNs prepared by the MN; or The information of the shared data forwarding address indicates the number of candidate target MNs using the same data forwarding address of the one candidate target SN.

6. The MN of claim 1, wherein the information for route optimization indicates at least one of the following: Identification of the one or more candidate target SNs; Information of a shared data forwarding address, which indicates the number of candidate target MNs using the same data forwarding address of the one candidate target SN; one or more first estimated arrival probabilities, each first estimated arrival probability being for the UE towards a corresponding candidate target SN of the one or more candidate target SNs prepared by the MN; or One or more second estimated arrival probabilities, each second estimated arrival probability is for the UE toward a corresponding candidate target SN in the one or more candidate target SNs prepared by another candidate target MN different from the MN.

7. The MN according to claim 5 or 6, wherein the information related to the number of candidate target MNs using the same data forwarding address of the one candidate target SN is indicated by the one candidate target SN via an SN add request confirm message or an SN modify request message.

8. The MN of claim 7, wherein the transceiver is configured to: transmitting, to the one candidate target SN, information indicating a first time based on which the information related to the number of candidate target MNs using the same data forwarding address of the one candidate target SN will be provided; and The information related to the number of candidate target MNs using the same data forwarding address of the one candidate target SN is received.

9. The MN according to claim 7, wherein the information related to the number of candidate target MNs using the same data forwarding address of the one candidate target SN is indicated by the one candidate target SN using a numerical value or at least using the identifiers of other candidate target MNs other than the MN using the same data forwarding address.

10. The MN of claim 6, wherein the transceiver is configured to: transmitting to the candidate target SN information indicating a first time based on a second estimated probability of arrival associated with the candidate target SN; and A message is received indicating the second estimated probability of arrival associated with the candidate target SN.

11. The MN of claim 6, wherein the transceiver is configured to: A destination for data forwarding for a SN terminated bearer is received from the source MN, wherein the destination is an identifier of a target SN determined by the source MN.

12. A master node MN, comprising: processor; and a transceiver coupled to the processor and configured to: transmitting a handover request for a conditional handover CHO with a secondary cell group SCG of the user equipment UE to a candidate target MN among the one or more candidate target MNs; and Receiving, from the candidate target MN, route optimization information for early data forwarding associated with at least one or more candidate target secondary nodes SN prepared by the candidate target MN, wherein the early data forwarding is for the CHO with the SCG.

13. A secondary node SN, comprising: processor; and a transceiver coupled to the processor and configured to: receiving first information about a conditional handover CHO with a secondary cell group SCG of a user equipment UE from a candidate target master control node MN; and Second information about route optimization for early data forwarding of the CHO with the SCG is transmitted to the candidate target MN.

14. The SN according to claim 13, wherein the second information indicates at least one of the following: The identifier of the SN; a random number assigned at the SN; or Information indicating that the same data forwarding address is shared by other candidate target MNs and the candidate target MN.

15. The SN according to claim 13, wherein the second information indicates at least one of the following: The identifier of the SN; Information related to the number of candidate target MNs using the same data forwarding address of the SN; or One or more second estimated arrival probabilities, each second estimated arrival probability is for the UE to be heading toward the SN prepared by another candidate target MN different from the candidate target MN.

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