Apparatus and method for resource optimization for handover

Abstract

Example embodiments of the present disclosure are directed to an apparatus and method for resource optimization for handover. Based on receiving a first addition request from a first target primary network node for addition of a secondary network node for preparation of one or more secondary target cells for handover of the terminal device, the first device transmits a first message to a second device of the secondary network node to reserve resources for the terminal device, wherein the first message comprises an identifier of the first target primary network node and a first identifier of the terminal device allocated by the first apparatus.

Description

Technical Field

[0001] Various example embodiments of the present disclosure relate generally to the field of telecommunications, and more particularly to enhanced methods, devices, apparatuses, and computer-readable storage media for resource optimization of handovers. Background Art

[0002] In Conditional Handover (CHO), a terminal device (e.g., UE) is configured with a CHO command that contains a target cell configuration and conditions for performing a handover for one or more target cells. The conditions are based on radio measurements of neighboring cells. An L1 / L2 triggered mobility (LTM) mechanism is provided for handover based on L1 measurement reports. Resources can be reserved on the target network node side for data forwarding in the handover. Summary of the invention

[0003] In a first aspect of the present disclosure, a first device is provided. The first device includes at least one processor; and at least one memory storing instructions, which, when executed by the at least one processor, cause a second device to at least perform: based on receiving a first add request for adding a secondary network node from a first target primary network node, the addition of the secondary network node is used for the preparation of one or more secondary target cells for handover of a terminal device, transmitting a first message to a second device of the secondary network node to reserve resources for the terminal device; and based on receiving a second add request for adding a secondary network node from a second target primary network node, the addition of the secondary network node is used for the preparation of one or more secondary target cells for handover of the terminal device, transmitting a second message to a second device to reserve resources for the terminal device, wherein the first message includes an identifier of the first target primary network node and a first identifier of the terminal device assigned by the first device, and the second message includes the first identifier of the terminal device and an identifier of the second target primary network node, or wherein a copy indication is included in the second message, but not in the first message, and the copy indication indicates the copying of the message for the terminal device.

[0004] In a second aspect of the present disclosure, a second device is provided. The second device includes at least one processor; and at least one memory, the at least one memory storing instructions, which, when executed by the at least one processor, cause the second device to at least perform: receiving a first message and a second message from a first device of a secondary network node to reserve resources for a terminal device; wherein the first message includes an identifier of a first target primary network node and a first identifier of the terminal device assigned by the first device, and the second message includes the first identifier of the terminal device and an identifier of the second target primary network node, or wherein a copy indication is included in the second message but not in the first message, and the copy indication indicates a copy of a message for the terminal device; based on the first message and the second message, determining whether a previous bearer context establishment has been initiated or established for the terminal device; and based on the result of the determination, transmitting a first response to the first message and a second response to the second message to the first device.

[0005] In a third aspect of the present disclosure, a device is provided. The device includes: at least one processor; and at least one memory, the at least one memory storing instructions, which, when executed by the at least one processor, cause a second device to at least perform: receiving a first message and a second message from a first device of a secondary network node to reserve resources for a terminal device; wherein the first message includes an identifier of a first target primary network node and a first identifier of the terminal device assigned by the first device, and the second message includes the first identifier of the terminal device and an identifier of the second target primary network node, or wherein a copy indication is included in the second message but not in the first message, and the copy indication indicates a copy of a message for the terminal device; based on the first message and the second message, determining whether a previous bearer context establishment has been initiated or established for the terminal device; and based on the result of the determination, transmitting a first response to the first message and a second response to the second message to the first device.

[0006] In a fourth aspect of the present disclosure, a method is provided. The method includes: based on receiving a first add request for adding a secondary network node from a first target primary network node, the addition of the secondary network node is used for preparation of one or more secondary target cells for handover of a terminal device, transmitting a first message to a second device of the secondary network node to reserve resources for the terminal device; and based on receiving a second add request for adding a secondary network node from a second target primary network node, the addition of the secondary network node is used for preparation of one or more secondary target cells for handover of the terminal device, transmitting a second message to the second device to reserve resources for the terminal device, wherein the first message includes an identifier of the first target primary network node and a first identifier of the terminal device allocated by the first device, and the second message includes the first identifier of the terminal device and an identifier of the second target primary network node, or wherein a copy indication is included in the second message but not in the first message, and the copy indication indicates copying of a message for the terminal device.

[0007] In a fifth aspect of the present disclosure, a method is provided. The method includes: receiving a first message and a second message from a first device of a secondary network node to reserve resources for a terminal device; wherein the first message includes an identifier of a first target primary network node and a first identifier of the terminal device assigned by the first device, and the second message includes the first identifier of the terminal device and the identifier of the second target primary network node, or wherein a copy indication is included in the second message but not in the first message, and the copy indication indicates a copy of a message for the terminal device; based on the first message and the second message, determining whether a previous bearer context establishment has been initiated or established for the terminal device; and based on the result of the determination, transmitting a first response to the first message and a second response to the second message to the first device.

[0008] In a sixth aspect of the present disclosure, a method is provided. The method includes: receiving an add request for adding a secondary network node from a first target primary network node, the addition of the secondary network node is used for preparing one or more secondary target cells for handover of a terminal device; determining whether a previous bearer context establishment has been initiated or established for the terminal device; blocking the initiation of a message to reserve resources for the terminal device to a second device of the secondary network node based at least on the determination that the previous bearer context establishment has been initiated or established for the terminal device; and transmitting feedback information for the add request to the first target primary network node, the feedback information indicating the resource reservation for the terminal device by the second device in the previous bearer context establishment.

[0009] In a seventh aspect of the present disclosure, a first device is provided. The first device includes: a component for transmitting a first message to a second device of the secondary network node to reserve resources for the terminal device based on receiving a first add request for adding a secondary network node from a first target primary network node, the addition of the secondary network node is used for preparation of one or more secondary target cells for handover of a terminal device; and a component for transmitting a second message to a second device to reserve resources for the terminal device based on receiving a second add request for adding a secondary network node from a second target primary network node, the addition of the secondary network node is used for preparation of one or more secondary target cells for handover of the terminal device, wherein the first message includes an identifier of the first target primary network node and a first identifier of the terminal device allocated by the first device, and the second message includes the first identifier of the terminal device and an identifier of the second target primary network node, or wherein a copy indication is included in the second message but not included in the first message, and the copy indication indicates a copy of the message for the terminal device to the second device.

[0010] In an eighth aspect of the present disclosure, a second device is provided. The second device includes a component for receiving a first message and a second message from a first device of a secondary network node to reserve resources for a terminal device, wherein the first message includes an identifier of a first target primary network node and a first identifier of the terminal device allocated by the first device, and the second message includes the first identifier of the terminal device and the identifier of the second target primary network node, or wherein a copy indication is included in the second message but not in the first message, and the copy indication indicates a copy of a message for the terminal device; a component for determining whether a previous bearer context establishment has been initiated or established for the terminal device based on the first message and the second message; and a component for transmitting a first response to the first message and a second response to the second message to the first device based on the result of the determination of the first device.

[0011] In a ninth aspect of the present disclosure, a third device is provided. The third device includes: a component for receiving an addition request for adding a secondary network node from a first target primary network node, the addition of the secondary network node is used for preparing one or more secondary target cells for handover of a terminal device; a component for determining whether a previous bearer context establishment has been initiated or established for the terminal device; a component for preventing the initiation of a message to reserve resources for the terminal device from a second device of the secondary network node based at least on the determination that the previous bearer context establishment has been initiated or established for the terminal device; and a component for transmitting feedback information for the addition request to the first target primary network node, the feedback information indicating the resource reservation for the terminal device by the second device in the previous bearer context establishment.

[0012] In a tenth aspect of the present disclosure, a computer-readable medium is provided, wherein the computer-readable medium includes instructions stored thereon, and the instructions are used to cause an apparatus to at least execute the method according to the fourth aspect.

[0013] In an eleventh aspect of the present disclosure, a computer-readable medium is provided, wherein the computer-readable medium includes instructions stored thereon, and the instructions are used to cause a device to at least execute the method according to the fifth aspect.

[0014] In a twelfth aspect of the present disclosure, a computer-readable medium is provided, wherein the computer-readable medium includes instructions stored thereon, and the instructions are used to cause a device to at least execute the method according to the sixth aspect.

[0015] It should be understood that the invention summary is not intended to identify the key features or essential features of the embodiments of the present disclosure, nor is it intended to limit the scope of the present disclosure. Other features of the present invention will become readily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Some example embodiments will now be described with reference to the accompanying drawings, in which:

[0017] Figure 1 shows a signaling flow for an example CHO procedure in a communication system;

[0018] Figure 2 shows a signaling flow for an example LTM process in a communication system;

[0019] Figure 3 shows the signaling flow of an example bearer context establishment procedure in case of a CHO request;

[0020] Figure 4 shows a signaling flow for bearer context establishment in a CHO scenario according to some example embodiments of the present disclosure;

[0021] Figure 5 shows a signaling flow for bearer context release according to some example embodiments of the present disclosure;

[0022] Figure 6 shows a signaling flow for bearer context establishment in an LTM scenario according to some example embodiments of the present disclosure;

[0023] Figure 7 shows a signaling flow for bearer context establishment in a CHO scenario according to some other exemplary embodiments of the present disclosure;

[0024] Figure 8 shows a signaling flow for bearer context release according to some example embodiments of the present disclosure;

[0025] Fig. 9 The signaling flow for bearer context establishment in an LTM scenario according to some other exemplary embodiments of the present disclosure is shown;

[0026] Fig.10 shows a signaling flow for bearer context establishment in a CHO scenario according to some further example embodiments of the present disclosure;

[0027] Fig.11 A flowchart showing a method implemented at a first device according to some example embodiments of the present disclosure is shown;

[0028] Fig.12 A flowchart showing a method implemented at a second device according to some example embodiments of the present disclosure is shown;

[0029] Fig.13 A flowchart showing a method implemented at a second device according to some example embodiments of the present disclosure is shown;

[0030] Fig.14 shows a simplified block diagram of a device suitable for implementing an example embodiment of the present disclosure; and

[0031] Fig.15 A block diagram of an example computer-readable medium is shown according to some example embodiments of the present disclosure.

[0032] Throughout the drawings, the same or similar reference numerals refer to the same or similar elements. DETAILED DESCRIPTION

[0033] The principle of the present invention will now be described with reference to some exemplary embodiments. It should be understood that these embodiments are described only for the purpose of illustration, and help those skilled in the art to understand and implement the present disclosure, without suggesting any limitation to the scope of the present disclosure. In addition to the embodiments described below, the embodiments described herein can be implemented in various ways.

[0034] In the following description and claims, unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs.

[0035] References in this disclosure to "one embodiment," "an embodiment," "an example embodiment," etc., indicate that the described embodiment may include a particular feature, structure, or characteristic, but not every embodiment necessarily includes the particular feature, structure, or characteristic. Moreover, such phrases do not necessarily refer to the same embodiment. Further, when a particular feature, structure, or characteristic is described in conjunction with an embodiment, it is considered to be within the knowledge of those skilled in the art to affect such feature, structure, or characteristic in conjunction with other embodiments (whether or not explicitly described).

[0036] It should be understood that, although the terms "first", "second", ... etc. in front of (multiple) nouns, etc. can be used in this article to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another element, and they do not limit the order of (multiple) nouns. For example, without departing from the scope of the exemplary embodiment, the first element can be referred to as the second element, and similarly, the second element can be referred to as the first element. As used herein, the term "and / or" includes any and all combinations of one or more listed terms.

[0037] As used herein, “at least one of: «a list of two or more elements» and “at least one of «a list of two or more elements» and similar expressions, where the list of two or more elements is connected by “and” or “or”, refer to at least any one of the elements, or at least any two or more of the elements, or at least all of the elements.

[0038] As used herein, unless explicitly stated, performing a step “in response to A” does not indicate that the step is performed immediately after “A” occurs, but may include one or more intermediate steps.

[0039] The terms used herein are only used for the purpose of describing specific embodiments and are not intended to limit the exemplary embodiments. As used herein, the singular forms "a", "an", and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that when used herein, the terms "comprises", "comprising", "has", "having", "includes", and / or "including" specify the presence of features, elements, and / or parts, etc., but do not exclude the presence or addition of one or more other features, elements, parts, and / or combinations thereof.

[0040] As used in this application, the term "circuitry" may refer to one or more or all of the following: (a) hardware circuit implementation only (e.g., implementation only in analog and / or digital circuits), and (b) a combination of hardware circuitry and software such as (where applicable): (i) a combination of analog and / or digital hardware circuits and software / firmware, and (ii) hardware(ies) with software (including digital signal processor(s)) processor, software, and any portion of memory(s) that work together to enable a device such as a mobile phone or a server to perform various functions; and (c) Hardware circuit(s) and / or processor(s), such as microprocessor(s) or portions of microprocessor(s), that require software (e.g., firmware) for operation, but the software may not be present when not required for operation.

[0041] This definition of circuitry applies to all uses of this term in this application, including in any claims. As a further example, as used in this application, the term circuitry also covers an implementation of only a hardware circuit or a processor (or multiple processors) or a portion of a hardware circuit or a processor and its (or its) accompanying software and / or firmware. For example and if applicable to the particular claim element, the term circuitry also covers a baseband integrated circuit or processor integrated circuit for a mobile device or a similar integrated circuit in a server, cellular network device, or other computing or network device.

[0042] As used herein, the term "communication network" refers to a network that complies with any suitable communication standard, such as New Radio (NR), Long Term Evolution (LTE), Advanced LTE (LTE-A), Wideband Code Division Multiple Access (WCDMA), High Speed ​​Packet Access (HSPA), Narrowband Internet of Things (NB-IoT), etc. In addition, the communication between the terminal device and the network device in the communication network can be performed according to any suitable generation communication protocol, including but not limited to the first generation (1G), second generation (2G), 2.5G, 2.75G, third generation (3G), fourth generation (4G), 4.5G, fifth generation (5G), sixth generation (6G) communication protocol and / or any other protocol currently known or developed in the future. The embodiments of the present disclosure can be applied to various communication systems. In view of the rapid development of communication, there are of course future types of communication technologies and systems that can implement the present disclosure. It should not be considered that the scope of the present disclosure is limited to the above-mentioned system.

[0043] As used herein, the term "network device" refers to a node in a communication network via which a terminal device accesses a network and receives services from it. A network device may refer to a base station (BS) or an access point (AP), such as a NodeB (NodeB or NB), an evolved NodeB (eNodeB or eNB), an NRNB (also known as a gNB), a remote radio unit (RRU), a radio head (RH), a remote radio head (RRH), a repeater, an integrated access and backhaul (IAB) node, a low power node (such as a femto), a micro-net, a non-terrestrial network (NTN) or non-terrestrial network equipment, such as satellite network equipment, a low earth orbit (LEO) satellite and a geosynchronous orbit (GEO) satellite, an aircraft network equipment, etc., depending on the terminology and technology applied. In some example embodiments, a radio access network (RAN) split architecture includes a centralized unit (CU) and a distributed unit (DU) at an IAB donor node. An IAB node includes a mobile terminal (IAB-MT) portion that behaves like a UE to a parent node, and a DU portion of an IAB node behaves like a base station to a next-hop IAB node.

[0044] The term "terminal device" refers to any terminal device capable of wireless communication. As an example and not limitation, the terminal device may also be referred to as a communication device, a user equipment (UE), a subscriber station (SS), a portable subscriber station, a mobile station (MS) or an access terminal (AT). The terminal device may include, but is not limited to, a mobile phone, a cellular phone, a smart phone, a voice over IP (VoIP) phone, a wireless local loop phone, a tablet computer, a wearable terminal device, a personal digital assistant (PDA), a portable computer, a desktop computer, an image capture terminal device such as a digital camera, a game terminal device, a music storage and playback device, a vehicle-mounted wireless terminal device, a wireless endpoint, a mobile station, a laptop embedded device (LEE), a laptop mounted device (LME), a USB dongle, a smart device, a wireless customer premises equipment (CPE), an Internet of Things (IoT) device, a watch or other wearable, a head mounted display (HMD), a vehicle, a drone, a medical device and an application (e.g., remote surgery), an industrial device and an application (e.g., a robot and / or other wireless devices operating in an industrial and / or automatic processing chain environment), a consumer electronic device, a device operating on a commercial and / or industrial wireless network, etc. The terminal device may also correspond to the mobile terminal (MT) part of an IAB node (eg, a relay node).In the following description, the terms "terminal device", "communication device", "terminal", "user equipment" and "UE" may be used interchangeably.

[0045] As used herein, the terms "resource", "transmission resource", "resource block", "physical resource block" (PRB), "uplink resource" or "downlink resource" may refer to any resource used to perform communication (e.g., communication between a terminal device and a network device), such as a resource in the time domain, a resource in the frequency domain, a resource in the spatial domain, a resource in the code domain, or any other combination of time, frequency, space and / or code domain resources to achieve communication. In the following, unless explicitly stated, resources in the frequency domain and the time domain will be used as examples of transmission resources for describing some example embodiments of the present disclosure. It should be noted that the example embodiments of the present disclosure are equally applicable to other resources in other domains.

[0046] In conditional handover (CHO), the terminal device is configured with a CHO command containing the target cell configuration and the conditions for performing handover for one or more target cells. The conditions are based on radio measurements of neighboring cells. CHO is designed to enable the terminal device to perform handover autonomously without the need for the serving cell to trigger the handover (HO) execution, for example after receiving a measurement report.

[0047] Figure 1 A signaling flow 100 for a CHO procedure in a communication system (e.g., within NR) is shown. Without loss of generality, the signaling flow 100 involves a terminal device 150, a source node 152, a target node 154, (multiple) other potential target nodes 156, a user plane function (UPF) 158, and an access and mobility management function (AMF) 159. Figure 1 As shown, in step 101, the terminal device 150 transmits a measurement report to the source node 152, the measurement report including the measurement results for the neighboring cells. It should be understood that the source node 152, the target node 154, and (multiple) other potential target nodes 156 may be radio access network (RAN) nodes, such as gNB or other RAN nodes.

[0048] In step 102, the source node 152 identifies the need to trigger CHO and makes a CHO decision. In step 103, the source node 152 transmits a CHO request to the target node 154 to request the target node 154 to prepare a target cell for CHO for the UE. In step 104, the source node 152 transmits the CHO request to other potential target nodes 156(s). The CHO configuration contains the radio protocol configuration that the terminal device 150 should apply when switching to the target cell of the target node.

[0049] At step 105, the target node 154 performs admission control and generates a CHO configuration. At step 106, the other potential target node(s) 156 perform admission control and generate a CHO configuration.

[0050] Further, in step 107 , the target node 154 transmits the generated CHO configuration as a CHO request confirmation message to the source node 152 , and in step 108 , the (multiple) other potential target nodes 156 also transmit the generated CHO configuration as a CHO request confirmation message to the source node 152 .

[0051] The source node 152 associates each CHO configuration with a CHO execution condition, which involves a measurement ID in the source cell measurement configuration. The measurement ID links the measurement object, which defines the frequency and quantity of the measurement (reference signal received power (RSRP), reference signal received quality (RSRQ), etc.), with the reporting configuration, which defines the parameters of the event that triggers the execution of CHO (offset, trigger time (TTT) or threshold). For intra-frequency switching, measurement event A3 is used, for example, Mn>Ms+Off, where Mn is the measurement of the neighboring cell, Ms is the measurement of the target cell, and Off is the offset. Here, if a certain TTT meets the above conditions, the terminal device will perform CHO. For inter-frequency HO, measurement event A5 can be used, where for a certain TTT, the terminal device checks whether the measurement of the serving cell drops below threshold 1 and whether the measurement of the target cell is better than threshold 2. Details of the measurement configuration and events can be found in the third (Generation Partnership Project 3GPP) technical specification TS38.331.

[0052] At step 109, the source node 152 transmits the CHO configurations of the prepared target cells together with their corresponding CHO executions to the terminal device 150. At step 110, the terminal device 150 evaluates the CHO execution conditions of each prepared target cell.

[0053] In step 111, if one of the CHO execution conditions is satisfied for the prepared target cell, the terminal device 150 applies the corresponding CHO configuration and performs handover, as shown in steps 112-119. The terminal device 150 may stop transmitting (TX) and receiving (RX) to / from the source node 152.

[0054] In step 112, the terminal device 150 transmits a PRACH preamble to the target node 154. In step 113, the target node 154 transmits a PRACH response to the terminal device 150. In step 114, the terminal device 150 transmits an RRC reconfiguration completion to the target node 152. In step 115, the target node 154 transmits a handover success to the source node 152. In step 116, the source node 152 stops TX / RX to / from the terminal device 150 and starts data forwarding. In step 117, the source node 152 transmits a secondary node (SN) state to the target node 154, and forwards data to the target node 154 in step 118. In step 119, the source node 152 cancels the CHO preparation of (multiple) other potential target nodes 156 that are not used / applied by the terminal device 150 for handover execution. Further, in step 120, a path switch is performed between the source node 152, the target node 154 and the UPF 158 and the AMF 159 may be involved.

[0055] CHO is also possible for terminal devices configured with dual connectivity. Here, in addition to preparing PCell candidates, the source MN node (controlling the primary cell, PCell) transmits a handover request to the target MN node (controlling the target PCell), which in turn selects a secondary node (controlling the target PSCell) and prepares it as part of the CHO preparation. When the CHO execution conditions are met, the terminal device performs access to the target PCell and PSCell.

[0056] One of the main differences between classic handover and conditional handover is the possibility of multiple preparations of the target cell. In the case of CHO, it is expected to be used more extensively to ensure that the terminal device has a prepared target cell when the execution conditions are met. This means that CHO reserves more resources at the target cell while waiting for execution than classic HO.

[0057] In case of multiple preparations, each target Master (MN) node may request its own target Secondary (SN) node to prepare the target secondary cell. Therefore, each target SN will also have to reserve the required resources. Because each target MNs receives the same measurements, it may happen that they all decide to prepare the same SN. Using the recent enhancements introduced by 3GPP for CHO, the SN is able to detect that SN add requests (possibly from different target MNs) are related to the same terminal device. In addition, by comparing the Secondary Cell Group (SCG) configurations, the target SN is able to identify that the target MN has provided the same configuration for SN-terminated bears.

[0058] The LTM mechanism is specified for handover based on L1 measurement reports. In some embodiments, LTM is handling intra-central unit (intra-CU) scenarios and the reference mechanism is Figure 2 is shown in . Figure 2 A signaling flow 200 of an example LTM process in a communication system for a Central Unit-User Plane (CU-UP) change, such as a gNB-CU-UP, is shown.

[0059] Without loss of generality, the signaling flow 200 involves a source gNB-distributed unit (DU) 250, a target gNB-DU 252, a source gNB-CU-control plane (CU-CP) 254, a source gNB-CU-UP 256, a target gNB-CU-UP 258, and an AMF / UPF 259. It should be understood that similar LTM processes may be applied to other similar network entities.

[0060] In step 201, the source gNB-DU 250 transmits a measurement report to the source gNB-CU-CP 254. In step 202, the source gNB-CU-CP 254 decides to initiate LTM configuration. In step 203, the source gNB-CU-CP 254 transmits a bearer context establishment request message to the target gNB-CU-UP 258 to establish a bearer context in the target gNB-CU-UP 258, and the bearer context establishment request message includes uplink (UL) TNL address information for NG-U.

[0061] In step 204, the target gNB-CU-UP 258 transmits a bearer context establishment response message to the source gNB-CU-CP254, and the bearer context establishment response message includes UL TNL address information for F1-U, downlink (DL) TNL address information for NG-U, and TNL address information for forwarding data to the target gNB-CU-UP 258.

[0062] In steps 205 and 206, the F1 UE context establishment procedure is performed to establish one or more bearers in the gNB-DU. Specifically, the source gNB-CU-CP 254 transmits a UE context establishment request to the target gNB-CU-UP 252 in step 205, and the target gNB-CU-UP 252 transmits a UE context establishment response to the source gNB-CU-CP 254 in step 206.

[0063] In step 207, the source gNB-CU-CP 254 transmits a DL RRC message, such as an RRC reconfiguration message, to the source gNB-DU 250. In step 208, the source gNB-DU 250 transmits a UL RRC message, such as an RRC reconfiguration complete message, to the source gNB-CU-CP 254.

[0064] In step 209, the terminal device transmits the lower measurement result to the source gNB-DU 200, and the source gNB-DU 250 decides to perform LTM to the candidate target cell.

[0065] In step 210, the source gNB-DU 250 transmits an LTM cell change notification message to the source gNB-CU-CP 254 with the selected target cell identity (ID).

[0066] In steps 211 and 212, the source gNB-CU-CP 254 performs a bearer context modification procedure to retrieve the Packet Data Convergence Protocol (PDCP) UL / DL status and exchange TNL address information for the bearer for data forwarding. Specifically, in step 211, the source gNB-CU-CP 254 transmits a bearer context modification request to the source gNB-CU-UP 256, and in step 212, the source gNB-CU-UP 256 transmits a bearer context modification response to the source gNB-CU-CP 254.

[0067] The source gNB-CU-CP 254 performs a bearer context modification procedure to transmit the DL TNL address information and PDCP UP / DL status for F1-U to the target gNB-CU-UP 258. Specifically, in step 213, the source gNB-CU-CP 254 transmits a bearer context modification request to the target gNB-CU-UP 258, and in step 214, the target gNB-CU-UP 258 transmits a bearer context modification response to the source gNB-CU-CP 254.

[0068] In step 215, data forwarding from the source gNB-CU-UP 256 to the target gNB-CU-UP 258 and the target gNB-DU 252 may be performed.

[0069] In step 216, the target gNB-DU 252 detects the terminal device in the target cell, and in step 217, the target gNB-DU 252 transmits an access success message to the source gNB-CU-CP 254.

[0070] In step 218, the path switching process is performed to update the DL TNL address information for NG-U to the core network. In step 219, the AMF / UPF 259 in the core network interacts with the source gNB-CU-UP 256 to end the marking packet, and in step 220, the AMF / UPF 259 transmits the new path to the source gNB-DU 250 and the target gNB-CU-UP 258.

[0071] In steps 221 and 222, a bearer context release procedure may be performed to release the UE context in the source gNB-DU 250. Specifically, in step 221, the source gNB-CU-CP 254 transmits a bearer context release command to the source gNB-CU-UP 256, and in step 222, the source gNB-CU-UP 256 transmits a bearer context release complete message to the source gNB-CU-CP 254.

[0072] In future communication systems, it is expected that the inter-CU mechanism for LTM may also include dual connectivity (DC) scenarios. This will lead to the same problems as identified in this IR.

[0073] In Rel.17, during the 3GPP discussions for CHO, the problem of forwarding the same data to a single target node was considered. Therein, multiple target cells can be prepared in the same target node. Since each target cell has a separate request, and both the target node and the source node are aware of the request related to the same terminal device (in the following HO request, the source node may include the UE ID received from the target node in response to the first HO request), it is up to the target node to process the request and optimally allocate the Tunnel Endpoint ID (TEID) and related resources. This consideration does not take into account dual connectivity (DC) operation, where the SCG configuration also needs to "match", that is, the different SCG configuration parts that identify the CHO configuration are the same between multiple target MNs.

[0074] Furthermore, schemes have been proposed that enable a target SN to identify additional requests related to the same terminal device, even if these requests come from different target MNs.

[0075] An alternative solution to this problem is to force the SN to manage the same data arriving via different paths, where an Addition Request SN identifies the preparation from another MN and assigns the same TEID to the request, the other MN being associated with the same terminal device and the same SCG configuration for the bearer terminated by the SN. Alternatively, if an indication is provided in advance to enable direct data forwarding between the source node and the target SN, the SN may indicate to the target MN that the allocated TEID may be shared. The source node will then understand that the TEID is shared and forward the data only once. Finally, another enhancement is that if one or more target MNs prefer to use indirect forwarding (packets for the target SN are first transmitted from the source node to the target MN, which in turn forwards them to the target SN), it may provide the target TEID from the target SN together with its own TEID.

[0076] Figure 3A signaling flow 300 of an example bearer context establishment procedure in the case of a CHO request in dual connectivity is shown. Without loss of generality, the signaling flow 300 involves a terminal device 350, a source MN 352, a target MN1 354, a target MN2 356, a target SN CU-CP 358, and a target SN CU-UP 359. It should be understood that the source MN 352, the target MN1 354, the target MN2 356, the target SN CU-CP 358, and the target SN CU-UP 359 may be RAN nodes, such as gNBs or other RAN nodes.

[0077] At step 301, the terminal device 350 connects to the source MN 352 and provides a radio link measurement report to the source MN 352. At 302, based on the measurements provided by the terminal device 350, the source MN 352 makes a CHO decision.

[0078] In step 303, the source MN transmits a CHO request message to the target MN1 354. In step 304, the source MN transmits a CHO request message to the target MN2 356.

[0079] In step 305, the target MN1 354 initiates an S node add request to the target SN CU-CP 358. The S node add request includes CHO information in the Xn interface between the target MN1 354 and the target SN CU-CP, SN add, source MN node ID, source MN node UE XnAP ID.

[0080] In step 306 , the target SN CU-CP 358 initiates a new bearer context establishment and transmits a bearer context establishment request to the target SN CU-UP 359 .

[0081] At step 307, the target SN CU-UP 359 replies with a bearer context setup response to the target SN CU-CP 358. The bearer context setup response includes the SCG configuration and the provided TEID for DL ​​data forwarding.

[0082] In step 308 , the target SN CU-CP 358 transmits an S Node Add Confirm message to the target MN1 354 .

[0083] In step 309, the target MN2 356 transmits an S-node add request to the target SN CU-CP 358. The S-node add request includes CHO information in the Xn interface between the target MN1 354 and the target SN CU-CP, SN add, source MN node ID, source MN node UE XnAP ID.

[0084] In step 310 , the target SN CU-CP 358 transmits a bearer context establishment request to the target SN CU-UP 359 .

[0085] In step 311, the target SN CU-UP 359 transmits a bearer context setup response to the target SN CU-CP 358. The bearer context setup response includes the SCG configuration and the provided TEID for DL ​​data forwarding.

[0086] In step 312, the target SN CU-CP 358 transmits an S node add confirmation message to the target MN2356.

[0087] At step 313, the target MN1 354 transmits a CHO request confirmation to the source MN 352. At step 314, the target MN2 356 transmits a CHO request confirmation to the source MN 352.

[0088] When the SCG bearer configuration contains SN-terminated bearers, the SN must allocate the required tunnel endpoints. Information about the allocated tunnel endpoint identification (TEID) is then forwarded to the source node, which can start data forwarding. In the case of CHO, it can be early data forwarding, which starts before the terminal device selects a target node for handover execution. Therefore, the source node transmits data to all prepared target nodes (after the target node has been prepared and configured to the terminal device). From the perspective of the target SN, if there are SN-terminated bearers, this means that the same data may be received for all allocated TEIDs. In turn, this requires allocating and managing separate downlink (DL) buffers for the same data. In practice, this leads to severe over-allocation of resources.

[0089] Existing solutions only partially solve the above problems. Figure 3 As depicted, although the CU-CP in the target SN can detect that S-Addition requests from different target MNs correspond to the same terminal device, the decision on reserving resources and allocating TEID is still made by the CU-UP, but the CU-UP is currently unaware of this information.

[0090] Furthermore, even if the CU-CP in the target SN can detect that the S-Addition requests from different target MNs correspond to the same UE, if the same gNB-CU-CP UE E1AP ID is indicated to the CU-UP for the second request without further indication whether this is from a different MN, an error will be raised at the CU-UP which rejects the bearer context establishment as indicated in TS 37.483 below: Table 1

[0091] To avoid this error, if different target MNs have different Data Radio Bearers (DRB) setup for the same terminal device, this would require two bearer context setup requests to the CU-UP, which would mean reserving twice the resources for the same terminal device.

[0092] The decision on configuring reserved resources for the SCG is the task of the CU-UP, which currently does not know in the bearer context establishment request that the request for the same terminal device comes from different MNs, and therefore cannot optimize resource reservation. This can still lead to problems with resource utilization, as resources will be reserved twice, and can also cause the target SN to receive the same data twice.

[0093] Example embodiments of the present disclosure address mobility in cellular and mobile communication systems such as Long Term Evolution (LTE) or New Radio (NR). More specifically, a method is proposed that further enhances data forwarding and associated buffer resource reservation for handover in CHO or LTM of a terminal device that has been configured for CHO or LTM to a candidate target cell(s).

[0094] In some example embodiments, at a first device (e.g., a CU-CP of a secondary node (also referred to as an SN CU-CP or a target SN CU-CP)), if an add request is received from a target master network node (also referred to as a target MN), the first device transmits a message for reserving resources for a terminal device to a second device of the secondary node.

[0095] In the first scheme, the message includes both an identifier of the target master network node (such as MN ID) and a first identifier of the terminal device assigned by the first device (such as CU-CP UE ID, CU-CP UE E1AP ID or gNB-CU-CP UEE1AP ID). Different identifiers of different target MNs that initiate add requests for the same terminal device will be included in the bearer context establishment or modification request to the second device. In the bearer context establishment or modification request, the same identifier of the terminal device assigned by the first device is included. The combination of the identifiers of the terminal device and the master node enables the second device (also called SN CU-UP or target SN CU-UP) to understand requests involving the same terminal device but from different target MNs.

[0096] In the second scenario, if the first device determines that a bearer context establishment for the specific terminal device has previously existed or an add request for preparation of the same terminal device has been received from a different target MN, the message to the second device includes a copy indication in the message to indicate the copy of the message for the terminal device. The first device may also include in the message an identifier of the terminal device assigned by the second device (e.g., CU-UP UE ID, CU-UP UE E1APID, or gNB-CU-UP UE E1APID), which was received by the first device from the second device in a previous request, which was given to the second device to identify the UE context.

[0097] In the third scheme, if the first device determines that a bearer context has previously been established for the specific terminal device or has received a prepared add request for the same terminal device from a different target MN, the first device will not initiate a message to the second device to trigger resource reservation for the terminal device.

[0098] Through any of the above-mentioned schemes, when different MNs request to add the same target SN, the addition of the target SN is used to prepare one or more secondary target cells for switching of the terminal device, and a single resource set (e.g., TEID) is allocated at the target SN for requests related to the same terminal device.

[0099] Specifically, in some embodiments, upon receiving an S node addition request from the CU-CP of the target SN, which indicates that it involves CHO, the CU-CP of the target SN determines whether a bearer context establishment for the specific terminal device has previously existed. If not, the CU-CP initiates a bearer context establishment request, and in addition to the gNB-CU-CP UE, the CU-CP also provides some identifiers of the request, such as the target MN ID (e.g., NG RAN node ID), so that the CU-UP of the target SN can determine whether it has provided SCG configuration and reserved resources for the terminal device. The combination of the gNB-CU-CP UE E1AP ID and the MN ID enables the CU-UP to understand requests related to the same UE, but from different target MNs.

[0100] Alternatively, if the CU-CP of the target SN determines that a bearer context establishment for this specific terminal device has previously existed from a different target MN, the CU-CP uses the same gNB-CU-CPUE E1AP ID and the new target MN ID when initiating the bearer context establishment request. Otherwise, the same unique UE E1AP ID needs to be used in the E1 interface, and comparison between the two DRB configurations cannot be performed.

[0101] As indicated above, the MN ID is required together with the same CU-CP UE E1AP ID in the E1 interface, because simply indicating the same CU-CP UE E1 AP ID for the bearer context establishment request without further indicating a different MN ID will throw an error at the CU-UP. Another advantage of the first scheme is that when two different target MNs have different DRBs established for the same UE, the same CU-CP UE E1AP ID is used in the bearer context establishment. As a result, the CU-UP can reply with the configuration in the bearer context establishment response to only the difference (differential) resource reservation to be established (e.g., difference (differential) DRB). This can avoid duplication of reserved resources.

[0102] In some example embodiments, in the event that one of the CHO preparations is released, the target MN will transmit an SN release request to the target SN CU-CP. The target SN CU-CP should transmit a bearer context release request to the target SN CU-UP, which needs to have the CU-CP UE E1AP ID address, together with the identifier used for this MN at the time of bearer establishment, such as the target MN ID. Using these two IDs, the target CU-UP can accept the release request, but keep the TEID and resource reservation as required by the UE, because the terminal device can perform CHO on another MN.

[0103] In some example alternative embodiments, upon receiving an S-node add request indicating that it involves CHO from the CU-CP of the target SN, the CU-CP of the target SN determines whether a bearer context establishment for the specific UE has previously existed. If not, the CU-CP initiates a normal bearer context establishment / modification request without further enhancement. Alternatively, if the CU-CP of the target SN determines that a bearer context establishment for the specific terminal device from a different target MN has previously existed, the CU-CP of the target SN includes the gNB-CU-UP UE E1AP ID in the bearer context establishment / modification request, and the gNB-CU-UP UE E1AP ID is received from the CU-UP in the first request to the CU-UP to identify the UE context. In addition, the CU-CP indicates a copy indication of the indication to the CU-UP, which may be a flag that, if established as true, notifies the CU-UP that the request for the same terminal device needs to be copied. The CU-UP can then determine that the request involves the same terminal device and needs to be copied, so it can reserve resources accordingly. Once the CU-UP answers the Bearer Context Setup Request with a Bearer Context Setup Response, the CU-UP includes a different gNB-CU-UP UE E1AP ID together with the TEID for DL ​​data forwarding that has been assigned to the previous request. In case of bearer release, different gNB-CU-UP UE E1AP IDs may identify the configuration of different target MNs. The advantage of this alternative approach compared to the first approach is that it requires minimal changes to the standard.

[0104] In some example embodiments, in the event that one of the CHO preparations is released, the target MN transmits an SN release request to the target SN CU-CP. The target SN CU-CP determines and maps the corresponding CU-UP UE E1AP ID to the target MN, and transmits a bearer context release request to the target SN CU-UP, which requires the CU-UP UE E1AP ID address corresponding to the target MN. Using this ID, the target SN CU-UP can accept the release request, but retain the TEID and resource reservation required by the UE, because the terminal device can perform CHO on another MN.

[0105] In some example alternative embodiments, upon receiving an S-node add request (indicating that it involves CHO) from the CU-CP of the target SN, the CU-CP of the target SN determines whether a bearer context has been previously established for the particular UE. If not, the CU-CP initiates a normal bearer context establishment request without further enhancements. Alternatively, the CU-CP decides not to trigger the bearer context establishment request / modification process, but to reuse the already allocated TEID from the previous configuration related to the same UE ID. The benefit of this alternative approach is that it reduces signaling because the new request does not require a context establishment request and response. However, considering the division of responsibilities between logical nodes, this scheme may not be enough, and in principle the reservation of resources should be decided by the CU-UP. In addition, in the case where different target MNs establish different DRBs for the same terminal device, the CU-CP may still need to contact the CU-UP to reserve resources for DRBs that currently have no reserved resources.

[0106] In the above scheme, in one embodiment, the target SN CU-UP will share the estimated arrival probability used in the F1 interface, because the probabilities of requests from two different target MNs will be different. Ultimately, when two different bearer context establishment requests originating from different target MNs arrive for the same terminal device, this information will be used at the decision point in the target SN CU-UP.

[0107] To better understand the example embodiments, reference will be made to some example signaling flows in a CHO scenario and an LTM scenario (eg, a dual connectivity scenario). Note that some example embodiments are described in terms of CHO, but it should be understood that the same scheme also applies to the LTM dual connectivity scenario.

[0108] Figure 4 A signaling flow 400 for bearer context establishment in a CHO scenario according to some example embodiments of the present disclosure is shown. Without loss of generality, the signaling flow 400 involves a terminal device 450, a source device MN 452, a target device MN1 454, a target device MN2 456, a target device SN CU-CP 458, and a target device SN CU-UP 459.

[0109] It should be understood that the source MN 452, the target MN1 454, the target MN2 456, and the target SN may be RAN nodes, such as gNB or other RAN nodes. The target MN1 454 may sometimes be referred to as the first target MN, and the target MN2 456 may sometimes be referred to as the second target MN. The target SN CU-CP 458 and the target SN CU-UP 459 may be separate parts in a subdivided architecture applied to the target SN. The target SN CU-CP 458 may sometimes be referred to as the first device, and the target MN2 456 may sometimes be referred to as the second device.

[0110] At step 401, the terminal device 450 connects to the source MN 452 and provides a radio link measurement report to the source MN 452. At 402, based on the measurements provided by the terminal device 450, the source MN 452 makes a CHO decision.

[0111] In step 403 , the source MN transmits a CHO request message to the target MN1 454 , the message also including a dual connection request for the terminal device 450 .

[0112] In step 404, the target MN1 454 initiates an add request (also referred to as an S node add request or a first add request) to the target SN CU-CP 458. The add request is a request for adding a secondary network node, which is used for preparing one or more secondary target cells for handover of the terminal device 450. In some example embodiments, the S node add request includes CHO information, SN addition, source MN node ID, and source MN node UE XnAP ID.

[0113] In step 405, the target SN CU-CP 458 determines that there is no bearer context for the terminal device 450. The target SN CU-CP 458 initiates a new bearer context establishment, and in step 406, transmits a first message to the target SN CU-UP 459 to reserve resources for the terminal device 450. In some example embodiments, the first message may be a first bearer context establishment request to the target SN CU-UP 459. The first bearer context establishment request includes both an identifier of the target MN1 454 and a first identifier of the terminal device 450 assigned by the target SN CU-CP 458, for example, including both the CU-CP UE E1AP ID and the target MN1 ID. In some alternative embodiments, the target SN CU-CP 458 may not need to determine whether there is a bearer context for the same terminal device 450, but may transmit a message including the first identifier of the terminal device 450 and an identifier of the target MN to the target SN CU-UP 459, which target MN is the target MN that initiates the add request.

[0114] In step 407, the target SN CU-UP 459 reserves resources for the first bearer context establishment request and replies to the target SNCU-CP 458 with a first response to the first message, for example, a first bearer context establishment response to the first bearer context establishment request. The first bearer context establishment response indicates a first resource reservation for the terminal device 450, for example, an SCG configuration and a TEID represented as SCG configuration 1 and TEID 1. In some example embodiments, the first bearer context establishment response may also indicate a TEID allocated for DL ​​data forwarding.

[0115] In some example embodiments, the first bearer context establishment response may further include a second identifier of the terminal device 450 allocated by the target SN CU-UP 459 , such as CU-UP UE E1AP ID1 .

[0116] At step 408, the target SN CU-CP 458 transmits an S Node Add Confirm to the target MN1 454, which indicates the first resource reservation for the terminal device 450, such as the SCG configuration and TEID for DL ​​data forwarding.

[0117] In step 409, the target MN1 454 replies to the source MN 452 with a CHO request confirmation including a CHO configuration (eg, CHO Config 1).

[0118] At step 410, source MN 452 also transmits a CHO request message to target MN2 456. In some example embodiments, the CHO request message may also include a dual connectivity request for terminal device 450.

[0119] In step 411, the target MN2 456 transmits an add request (also referred to as a second add request or an S node add request) to the target SN CU-CP 458. This add request is also a request for adding a secondary network node, which is used to prepare one or more secondary target cells for handover of the terminal device. In some example embodiments, the second S node add request includes CHO information, SN addition, source MN node ID, and source MN node UE XnAP ID.

[0120] In step 412, the target SN CU-CP 458 determines that a bearer context already exists for the terminal device 450 and initiates a new bearer context establishment indicating the same CU-CP UE E1AP ID used in the previous context establishment request. This determination may be based on associating the source MN ID with the source MN UE XnAP ID, where the source MN UE XnAP ID matches the previous configuration.

[0121] Furthermore, the target SN CU-CP 458 includes the same UE CU-CP E1AP ID and the new target MN2 ID as used in the previous context establishment request in step 406 in the bearer context establishment request.

[0122] In step 413, the target SN CU-CP 458 initiates a new bearer context establishment and transmits a second message to the target SN CU-UP 459 to reserve resources for the terminal device 450. In some example embodiments, the second message may be a second bearer context establishment request to the target SN CU-UP 459. The second bearer context establishment request includes an identifier of the target MN2 456 and a first identifier of the terminal device 450 assigned by the target SN CU-CP 458, for example, including both the target MN2 ID and the CU-CP UE E1AP ID.

[0123] In some alternative embodiments, the target SN CU-CP 458 may not need to determine whether there is a bearer context for the same terminal device 450, but may transmit a message including a first identifier of the terminal device 450 and an identifier of the target MN to the target SN CU-UP 459, which target MN is the target MN that initiates the add request.

[0124] In steps 414 and 415, the target SN CU-UP 459 detects that the second message concerns the same terminal device, the second message has provided the SCG configuration for the terminal device, and the second message has reserved resources for the terminal device, so the second message is responded with a bearer context establishment response, which indicates the same configuration and TEID (for example, SCG configuration 1 and TEID 1).

[0125] Specifically, at step 414, the target SN CU-UP 459 detects that the target MN2 456 wants to reserve resources already reserved for the target MN1 for the same terminal device based on the identifier contained in the second bearer context establishment request, and it provides back the same SCG configuration and TEID.

[0126] In step 415 , the target SN CU-UP 459 transmits a second response to the second message (eg, a second bearer context establishment response to the second bearer context establishment request) to the target SN CU-CP 458 .

[0127] In some example embodiments, the second bearer context establishment response may indicate the first resource reservation for the terminal device as in the first bearer context establishment response. In some example embodiments, the second bearer context establishment response may indicate a difference between the second resource reservation for the terminal device in response to the second message and the first resource reservation for the terminal device in response to the first message. Figure 4 In the example, the case where the same resource configuration (e.g., SCG configuration 1 and TEID 1) is provided because the target MN1 454 and the target MN2 456 have the same DRB setup for the terminal device 450 has been demonstrated. In the case where the target MN2 has a different DRB setup for the terminal device 450 in the bearer context setup response, the target SN CU-UP 459 can reply with only the difference (delta) configuration without reserving resources twice.

[0128] In some example embodiments, the second bearer context establishment response may further include a third identifier of the terminal device 450 assigned by the target SN CU-UP459 (e.g., CU-UP UE E1AP ID2), which is different from the second identifier of the terminal device assigned by the second device (e.g., CU-UP UE E1AP ID1).

[0129] At step 416, the target SN CU-CP 458 transmits an S Node Add Ack message to the target MN2 456, indicating the SCG configuration and TEID (SCG Config1 and TEID1) for DL ​​data forwarding.

[0130] At step 417, target MN2 456 transmits a CHO request confirmation to source MN 452. The CHO request confirmation may include a new CHO configuration (e.g., CHO Configuration 2). At step 418, source MN 452 transmits an RRC reconfiguration message to terminal device 450 to configure it with the CHO configuration (e.g., CHO Config1, CHO Config2).

[0131] Figure 5 A signaling flow 500 for bearer context release according to some example embodiments of the present disclosure is shown.

[0132] In step 501, the terminal device 450 prepares a CHO with a target MN1 454 and a target SN with a target MN2 456, and the target SN CU-UP 459 reserves the same resources for both preparations.

[0133] In step 502, the terminal device 450 transmits a measurement report to the source MN 452. In step 503, the source MN 452 makes a CHO release decision. In step 504, the source MN 452 cancels the CHO preparation of the target MN1 454.

[0134] In step 505, the target MN1 454 transmits a first release request to the target SN CU-CP 458, where the first release request is used to release the auxiliary network node used for the handover of the terminal device 450, such as an S node release request.

[0135] In step 506, the target SN CU-CP 458 determines that multiple target MNs have requested the addition of secondary network nodes, the addition of secondary network nodes is used for the preparation of one or more secondary target cells for the switching of the terminal device 450, and the same SN has been prepared for the same terminal device 450. The target SN CU-CP 458 can indicate the bearer context release of the target MN1 454 to the target SN CU-UP 459 by including the target MNID. Specifically, the target SN CU-CP 458 transmits a first bearer context release message to the target SN CU-UP 459, wherein the first bearer context release message includes an identifier of the target MN1 454 (e.g., target MN1 ID) and a first identifier of the terminal device 450 assigned by the target SN CU-CP 458 (e.g., CU-CP UE E1AP ID).

[0136] In step 507, the target SN CU-CP 458 transmits a first bearer context release message (e.g., a bearer context release command) to the target SN CU-UP 459. The first bearer context release message includes the first identifier (e.g., CU-CP UE E1AP ID) address of the terminal device 450 and the identifier of the target MN1 454 (e.g., target MN1 ID).

[0137] In step 508, the target SN CU-UP 459 determines that the resource reservation for the terminal device 450 is reserved with respect to at least another target master network node based on the first bearer context release message. The target SN CU-UP 459 accepts the release request but does not release the resources because the target MN2 also needs these resources. Using these two IDs, the target SN CU-UP 459 can accept the release request but keep the TEID and resource reservation as needed by the terminal device 450 because the terminal device 450 can perform CHO on another MN.

[0138] In step 509 , the target SN CU-UP 459 transmits a first bearer context release complete message to the target SN CU-CP 458 .

[0139] Steps 507, 508 and 509 are required if all ongoing CHO configurations are notified to the target SN CU-UP 459. Otherwise, in some embodiments, the release does not need to be notified either.

[0140] In some example embodiments, in the case of releasing one of the CHO preparations, the target MN1 454 will transmit an SN release request to the target SN CU-CP 458. The target SN CU-CP 458 should transmit a bearer context release request to the target SN CU-UP 459, and the bearer context release needs to have the CU-CP UE E1APID address together with the target MN ID. Using these two IDs, the target SN CU-UP 459 can accept the release request, but keep the TEID and resource reservation as required by the terminal device 450, because the terminal device 450 can perform CHO on another MN.

[0141] In step 510, the target SN CU-CP 458 transmits an S Node Release Request Confirm to the target MN1 454. In step 511, the source MN 452 transmits an RRC reconfiguration message to the terminal device 450.

[0142] Figure 6 FIG. 6 shows a signaling flow 600 for bearer context establishment in an LTM scenario according to some example embodiments of the present disclosure. Figure 5 Some example embodiments discussed in the CHO scenario are also applicable to the LTM scenario and are therefore not repeated for the sake of brevity.

[0143] At step 601, the terminal device 450 connects to the source MN 452 and transmits a measurement report, such as a radio link measurement report, to the source MN 452. At 602, based on the measurements provided by the terminal device 450, the source MN 452 makes an LTM configuration release decision.

[0144] In step 603 , the source MN 452 transmits an LTM request message to the target MN1 454 , the message also including a dual connection request for the terminal device 450 .

[0145] At step 604, the target MN1 454 transmits an S-node add request to the target SN CU-CP 458. The add request is a request for adding a secondary network node, and the addition of the secondary network node is used for the preparation of one or more secondary target cells for CHO of the terminal device 450. In some example embodiments, the S-node add request includes information of SN addition, source MN node ID, and source MN node UE XnAP ID.

[0146] In step 605, the target SN CU-CP 458 determines that there is no bearer context for the terminal device 450 and initiates a new bearer context establishment. In step 606, the target SN CU-CP 458 transmits a first message, such as a bearer context establishment request, to the target SN CU-UP 459. The bearer context establishment request includes both an identifier of the target MN1 454 and a first identifier of the terminal device 450 assigned by the target SN CU-CP 458, for example, including both the CU-CP UE E1AP ID and the target MN1ID.

[0147] In step 607, the target SN CU-UP 459 reserves resources for the request and transmits a bearer context setup response to the target SN CU-CP 458, which also indicates the TEID allocated for DL ​​data forwarding.

[0148] At step 608, the target SN CU-CP 458 transmits an S Node Add Acknowledge message to the target MN1 454, which indicates the SCG configuration and TEID for DL ​​data forwarding.

[0149] In step 609, the target MN1 454 transmits an LTM request confirmation to the source MN 452.

[0150] In step 610, the source MN 452 also transmits an LTM request message to the target MN2 456, which also includes a dual connection request for the terminal device 450. In step 611, the target MN2 456 transmits an S node add request to the target SN CU-CP 458.

[0151] At step 612, the target SN CU-CP 458 determines that a bearer context for the terminal device 450 already exists, and initiates a new bearer context establishment indicating the same CU-CP UE E1AP ID used in the previous context establishment request.

[0152] The determination may be based on associating the source MN ID with the source MN UE XnAP ID, wherein the source MN UE XnAP ID matches the previous configuration. For example, the determination may be based on determining that the bearer context establishment request contains the same CU-CP UE E1AP ID and the new target MN2 ID, wherein the same CU-CP UE E1AP ID was used in the previous context establishment request of step 606.

[0153] In step 613, the target SN CU-CP 458 transmits a bearer context establishment request to the target SN CU-UP 459. The bearer context establishment request includes the target MN2 ID and the CU-CP UE E1AP ID.

[0154] In steps 614 and 615, the target SN CU-UP 459 detects that the request concerns its same terminal device for which it has provided SCG configuration and has reserved resources, so it answers with a Bearer Context Setup Response indicating the same configuration and TEID.

[0155] Specifically, in step 614, the target SN CU-UP 459 detects that the target MN2 wants to reserve the resources that have been reserved for the target MN1 for the same terminal device, and it provides back the same SCG configuration and TEID.

[0156] In step 615 , the target SN CU-UP 459 transmits a bearer context establishment response to the target SN CU-CP 458 .

[0157] At step 616, the target SN CU-CP 458 transmits an S Node Add Ack message to the target MN2 456, which indicates the SCG configuration and TEID for DL ​​data forwarding.

[0158] In step 617, the target MN2 456 transmits the LTM request confirmation to the source MN 452.

[0159] In step 618, the source MN 452 transmits an RRC reconfiguration message to the terminal device 450 to configure the terminal device 450 with the LTM configuration.

[0160] Although not shown, it should be understood that the bearer context release process in the LTM scenario can be the same as that in the CHO scenario (see Figure 5 discussed).

[0161] Figure 7 A signaling flow 700 for bearer context establishment in a CHO scenario according to some further example embodiments of the present disclosure is shown. In these example embodiments, if the target SN CU-CP 458 determines that a bearer context for the terminal device 450 already exists, a copy indication may be included in the bearer context establishment request.

[0162] At step 701, the terminal device 450 connects to the source MN 452 and transmits a measurement report, such as a radio link measurement report, to the source MN 452. At 702, based on the measurements provided by the terminal device 450, the source MN 452 makes a CHO decision.

[0163] In step 703 , the source MN 452 transmits a CHO message to the target MN1 454 , where the CHO message also includes a dual connection request for the terminal device 450 .

[0164] In step 704, the target MN1 454 transmits a first S node add request to the target SN CU-CP 458. The first S node add request includes CHO information, SN addition, source M-NG-RAN node ID, and source M-NG-RAN node UEXnAP ID.

[0165] In step 705, the target SN CU-CP 458 determines that this is a new request and that resources have not been previously reserved for the terminal device 450, and therefore transmits a first bearer context establishment request to the target SN CU-UP 459. The first bearer context establishment request includes a first identifier of the terminal device 450 assigned by the target SN CU-CP 458, such as gNB-CU-CP UE E1APID or CU-CP UE E1AP ID. The first bearer context establishment request includes a second identifier of the terminal device assigned by the target SN CU-UP 459, such as CU-UP UE E1AP ID1.

[0166] In step 706, the target SN CU-UP 459 reserves resources for the request and transmits a first response to the first message, for example, a first bearer context establishment response to the first bearer context establishment request, to the target SN CU-CP 458. The first bearer context establishment response indicates a first resource reservation for the terminal device 450. In some example embodiments, the first bearer context establishment response may also indicate an allocated TEID for DL ​​data forwarding. In some example embodiments, the first bearer context establishment response may further include a second identifier of the terminal device 450 allocated by the target SN CU-UP 459, for example, CU-UP UE E1AP ID1.

[0167] In step 707, the target SN CU-CP 458 transmits a CHO request answer to the target MN1 454. In step 708, the target MN1 454 transmits a CHO request confirmation to the source MN 452.

[0168] In step 709, the source MN 452 also transmits a CHO request message to the target MN2 456, and the CHO request message also includes a dual connection request for the terminal device 450. In step 710, the target MN2 456 transmits a second S node addition request to the target SN CU-CP 458. The second S node addition request includes CHO information, SN addition, source M-NG-RAN node ID, and source M-NG-RAN node UEXnAP ID.

[0169] In step 711, the target SN CU-CP 458 determines that the second S-Node add request corresponds to the same terminal device 450 with the same SCG configuration, and resources and allocated TEIDs have been reserved.

[0170] In step 712 , the target SN CU-CP 458 transmits a second bearer context establishment request or a bearer context establishment modification request to the target SN CU-UP 459 , which second bearer context establishment request or bearer context establishment modification request indicates the CU-CP UE E1AP ID and the CU-UP UE E1AP ID received from step 706 .

[0171] In addition, the target SN CU-CP 458 may indicate a copy indication in the second bearer context establishment request or the bearer context establishment modification request to indicate the copy of the message of the terminal device. In some examples, the copy indication may be configured via a copy flag, and the copy flag may be set to true to indicate to the target SN CU-UP 459 that this is a copy request for the same terminal device. If the flag value is set to true, it indicates that a copy request for the same terminal device has arrived.

[0172] In step 713, the target SN CU-UP 459 determines that the duplicate flag is true and makes resource reservation accordingly, knowing that it is for the same terminal device, and it can respond to the target SN CU-CP 458 with the new CU-UP UE E1AP ID of the target MN2 456. The target SN CU-UP 459 determines that a previous bearer context establishment has been initiated or established for the terminal device 450 based on the duplicate flag and the previously assigned CU-UP UE E1AP ID.

[0173] In some example embodiments, in steps 705 and 706, the copy flag in the bearer context establishment request may be set to "false" to indicate that the bearer context establishment request is not a copy, and then the target SN CU-UP 459 may reserve new resources for the request.

[0174] In step 714 , the target SN CU-UP 459 transmits a bearer context establishment or modification response indicating the SCG configuration and TEID and the newly allocated CU-UP UE E1AP ID (eg, CU-UP UE E1AP ID2 ) to the target SN CU-CP 458 .

[0175] In some example embodiments, the second bearer context establishment response may indicate the first resource reservation for the terminal device as in the first bearer context establishment response. In some example embodiments, the difference between the second resource reservation for the terminal device in response to the second message and the first resource reservation for the terminal device in response to the first message. Figure 7 In the embodiment, it has been demonstrated that the same resource configuration (e.g., SCG configuration 1 and TEID1) is provided because the target MN1 454 and the target MN2 456 have the same DRB setup for the terminal device 450. In the case where the target MN2 has a different DRB setup for the terminal device 450 in the bearer context setup response, the target SN CU-UP 459 can reply with only the difference (delta) configuration and not reserve resources twice.

[0176] At step 715, the target SN CU-CP 458 transmits an S Node Add Confirm message to the target MN2 456, which indicates the SCG configuration and TEID for DL ​​data forwarding.

[0177] In step 716, the target MN2 456 transmits a CHO request confirmation to the source MN 452. In step 718, the source MN 452 transmits an RRC reconfiguration message to the terminal device 450 to configure it with the CHO configuration.

[0178] Figure 8 A signaling flow 800 for bearer context release according to some further example embodiments of the present disclosure is shown.

[0179] In step 801, the terminal device 450 prepares a CHO with a target MN1 454 and a target SN with a target MN2 456, and the target SN CU-UP 459 reserves the same resources for both preparations.

[0180] In step 802, the terminal device 450 transmits a measurement report to the source MN 452. In step 803, the source MN 452 makes a CHO release decision. In step 804, the source MN 452 cancels the CHO preparation of the target MN1 454.

[0181] In step 805, the target MN1 454 transmits an S Node release request to the target SN CU-CP 458. In step 806, the target SN CU-CP 458 determines that the release request is from the target MN1 454 and uses the corresponding allocated CU-UP UE E1AP ID for release.

[0182] In step 807, the target SN CU-CP 458 transmits a bearer context release request to the target SN CU-UP 459. The bearer context release request includes the gNB-CU-CP UE E1AP ID and the gNB-CU-UP UE E1AP ID.

[0183] In step 808 , the target SN CU-UP 459 accepts the release request but does not release the resources because the target MN2 456 also needs these resources. In step 809 , the target SN CU-UP 459 transmits a bearer context release complete message to the target SN CU-CP 458 .

[0184] Steps 807, 808 and 809 are required if all ongoing CHO configurations are notified to the target SN CU-UP 459. Otherwise, in some embodiments, the release does not need to be notified either.

[0185] In the case where one of the CHO preparations is released, the target MN1 454 transmits an SN release request to the target SN CU-CP 458. The target SN CU-CP 458 determines the corresponding CU-UP UE E1AP ID and maps it to the target MN1 454, and transmits a bearer context release request to the target SN CU-UP 459, which needs to have a CU-UP UE E1AP ID address corresponding to the target MN1 454. Using these IDs, the target SN CU-UP 459 can accept the release request, but keep the TEID and resource reservation as required by the terminal device 450, because the terminal device 450 can perform CHO on another MN.

[0186] In step 810, the target SN CU-CP 458 transmits an S-NODE release request confirmation to the target MN1 454. In step 811, the source MN 452 transmits an RRC reconfiguration message to the terminal device 450.

[0187] Although not shown, it should be understood that the bearer context release process in the LTM scenario can be the same as that in the CHO scenario (see Figure 5 discussed).

[0188] Fig. 9 FIG. 9 shows a signaling flow 900 for bearer context establishment in an LTM scenario according to some further example embodiments of the present disclosure. Figure 7 Some example embodiments discussed in the CHO scenario are also applicable to the LTM scenario and are therefore not repeated for the sake of brevity.

[0189] At step 901, the terminal device 450 connects to the source MN 452 and transmits a measurement report, such as a radio link measurement report, to the source MN 452. At step 902, based on the measurements provided by the terminal device 450, the source MN 452 makes an LTM decision.

[0190] In step 903 , the source MN 452 transmits an LTM request message to the target MN1 454 , where the LTM request message also includes a dual connection request for the terminal device 450 .

[0191] In step 904, the target MN1 454 transmits an S-node add request to the target SN CU-CP 458. The S-node add request includes LTM information, SN addition, source M-NG-RAN node ID, and source M-NG-RAN node UE XnAP ID.

[0192] In step 905, the target SN CU-CP 458 determines that this is a new request and that resources have not been previously reserved for the terminal device 450, and therefore transmits a bearer context establishment request to the target SN CU-UP 459. The bearer context establishment request includes the gNB-CU-CP UE E1AP ID.

[0193] At step 906 , the target SN CU-UP 459 reserves resources for the request and transmits a bearer context setup response to the target SN CU-CP 458 , which also indicates the TEID allocated for DL ​​data forwarding.

[0194] In step 907, the target SN CU-CP 458 transmits an S Node Add Confirm message to the target MN1 454, which indicates the SCG configuration and TEID for DL ​​data forwarding.

[0195] At step 908 , the target MN1 454 transmits an LTM request confirmation to the source MN 452 .

[0196] In step 909, the source MN 452 also transmits an LTM request message to the target MN2 456, which also includes a dual connection request for the terminal device 450. In step 910, the target MN2 456 transmits an S node add request to the target SN CU-CP 458.

[0197] In step 911, the target SN CU-CP 458 determines that the second S-Node add request corresponds to the same terminal device 450 with the same SCG configuration, and resources and allocated TEIDs have been reserved.

[0198] In step 912, the target SN CU-CP 458 transmits a bearer context establishment request to the target SN CU-UP 459, and the target SN CU-UP 459 indicates that resources have been reserved using the already existing configured ID. The ID may be the gNB-CU-CP UE E1AP ID. For example, the bearer context establishment request may indicate the gNB-CU-CP UE E1AP ID by also indicating the gNB-CU-CP UE E1AP ID provided in step 906.

[0199] Furthermore, the target SN CU-CP 458 may indicate a copy flag to the target SN CU-UP 459, which is set to true to indicate to the target SN CU-UP 459 that this is a copy request for the same terminal device.

[0200] In one example, the target SN CU-UP 459 may determine that the copy flag is true and knows that it is making corresponding resource reservations for the same terminal device, and it may respond to the target SN CU-CP 458 with a new CU-UP UE E1AP ID (second target MN). In step 913, the target SN CU-UP 459 may reply with a bearer context setup response indicating the SCG configuration and TEID for DL ​​data forwarding, which is the same as the previously existing configuration.

[0201] In another example, the target SN CU-UP 459 may reply with a bearer context establishment failure, which indicates a new cause of rejection and the target SN CU-CP 458 should reuse the existing configuration and TEID.

[0202] In step 914 , the target SN CU-UP 459 may transmit a bearer context establishment / modification response to the target SN CU-CP 458 , wherein the target SN CU-UP 459 indicates the SCG configuration and TEID, but a different CU-UP UE1AP ID compared to step 906 .

[0203] At step 915, the target SN CU-CP 458 transmits an S Node Add Ack message to the target MN2 456, which indicates the SCG configuration and TEID for DL ​​data forwarding.

[0204] At step 916 , the target MN2 456 transmits an LTM request confirmation to the source MN 452 .

[0205] In step 917, the source MN 452 transmits an RRC reconfiguration message to the terminal device 450 to configure the terminal device 450 with the LTM configuration.

[0206] Fig.10 FIG. 1 shows a signaling flow 1000 for establishing a bearer context in a CHO scenario according to some further exemplary embodiments of the present disclosure. Fig.10 A similar mechanism as described is applicable at the target SN CU-CP 458 in the LTM scenario.

[0207] At step 1001, the terminal device 450 connects to the source MN 452 and transmits a measurement report, such as a radio link measurement report, to the source MN 452. At step 1002, based on the measurements provided by the terminal device 450, the source MN 452 makes a CHO decision.

[0208] In step 1003 , the source MN 452 transmits a CHO request message to the target MN1 454 , where the CHO request message also includes a dual connectivity request for the terminal device 450 .

[0209] At step 1004, the target MN1 454 transmits an S-node add request to the target SN CU-CP 458. The S-node add request includes CHO information, SN addition, source M-NG-RAN node ID, and source M-NG-RAN node UEXnAP ID.

[0210] In step 1005, the target SN CU-CP 458 transmits a bearer context establishment request to the target SN CU-UP 459. The bearer context establishment request includes the gNB-CU-CP UE E1AP ID. In some example embodiments, based on determining that a previous bearer context establishment has not been initiated or established for the terminal device, the target SN CU-CP 458 transmits a bearer context establishment request to the target SN CU-UP 459 to request a new resource reservation, the request including at least an identifier of the terminal device allocated by the first device.

[0211] At step 1006 , the target SN CU-UP 459 reserves resources for the request and transmits a bearer context setup response to the target SN CU-CP 458 , which also indicates the TEID allocated for DL ​​data forwarding.

[0212] At step 1007, the target SN CU-CP 458 transmits an S Node Add Confirm message to the target MN1 454, which indicates the SCG configuration and TEID for DL ​​data forwarding.

[0213] At step 1008, the target MN1 454 transmits a CHO request reply including the CHO configuration to the source MN 452.

[0214] At step 1009 , the source MN 452 also sends a CHO request message to the target MN2 456 , the CHO request message also including a dual connectivity request for the terminal device 450 .

[0215] At step 1010, the target MN2 456 transmits an S-node add request to the target SN CU-CP 458. The S-node add request includes CHO information, SN add, source M-NG-RAN node ID, source M-NG-RAN node UEXnAP ID.

[0216] In some example embodiments, the target SN CU-CP 458 blocks initiation of a bearer context establishment request to the target SN CU-UP 459 based on a determination that a previous bearer context establishment has been initiated or established for the terminal device 450. The target SN CU-CP 458 transmits feedback information for the add request to the target MN2 456, the feedback information indicating that the target SN CU-UP 459 reserved resources for the terminal device 450 in the previous bearer context establishment. Specifically, in step 1011, the target SN CU-CP 458 determines that the request corresponds to the same terminal device 450 with the same SCG configuration, and it has reserved resources and allocated TEID, so it does not initiate a new context establishment request, but utilizes the previously configured resources. In step 1012, the target SN CU-CP 458 transmits an S Node Add Confirmation message to the target MN2 456, indicating the same SCG configuration and TEID for DL ​​data forwarding as in step 1007.

[0217] In step 1013, the target MN2 456 transmits a CHO request confirmation to the source MN 452. In step 1014, the source MN 452 transmits an RRC reconfiguration message to the terminal device 450.

[0218] Fig.10 The process discussed in benefits from the fact that it reduces signaling since new requests do not require a context establishment request and response.

[0219] In the above process, one embodiment may be that the target SN CU-UP 459 will share the estimated arrival probability used in the F1 interface, since the probability will be different for requests from two different target MNs. Ultimately, this information will be used at the decision point of the target SN CU-UP when two different bearer context establishment requests come for the same terminal device originating from different target MNs. Example Method

[0220] Fig.111 is a flowchart of an example method 1100 implemented at a first device according to some example embodiments of the present disclosure. For discussion purposes, the first device (e.g., Figures 4 to 10 Method 1100 is described from the perspective of the target SN CU-CP 458 in the example.

[0221] At block 1110, based on receiving a first add request for adding a secondary network node from a first target primary network node, the addition of the secondary network node being used for preparation of one or more secondary target cells for handover of a terminal device, the first device sends a request to the secondary network node (e.g., Figures 4 to 10 A second device of the target SN CU-UP 459 in the transmission transmits a first message to reserve resources for the terminal device.

[0222] At box 1120, based on receiving a second add request for adding a secondary network node from the second target primary network node, the addition of the secondary network node is used for preparation of one or more secondary target cells for switching of the terminal device, the first device transmits a second message to the second device to reserve resources for the terminal device, wherein the first message includes an identifier of the first target primary network node and a first identifier of the terminal device allocated by the first device, and the second message includes the first identifier of the terminal device and the identifier of the second target primary network node, or a copy indication is included in the second message but not in the first message, and the copy indication indicates the copying of the message for the terminal device.

[0223] In some example embodiments, a first device receives a first response to a first message from a second device, the first response indicating a first resource reservation for a terminal device; and receives a second response to a second message from the second device, the second response indicating: the first resource reservation for the terminal device as in the first response, or a difference between the second resource reservation for the terminal device in response to the second message and the first resource reservation for the terminal device in response to the first message.

[0224] In some example embodiments, the first response includes a second identifier of the terminal device assigned by the second apparatus, and wherein the second response includes a third identifier of the terminal device assigned by the second apparatus, the third identifier being different from the second identifier of the terminal device assigned by the second apparatus.

[0225] In some example embodiments, the first message and / or the second message may be a bearer context establishment request or a bearer context modification request. In some example embodiments, the first response and / or the second response may be a bearer context establishment response or a bearer context modification response.

[0226] In some example embodiments, a first device receives a first release request from a target primary network node, the first release request being used to release a secondary network node for switching of a terminal device; if it is determined that multiple target primary network nodes have requested the addition of secondary network nodes, the addition of secondary network nodes being used to prepare one or more secondary target cells for switching of the terminal device, a first bearer context release message is transmitted to a second device, wherein the first bearer context release message includes a first identifier of the terminal device and an identifier of the target primary network node; and a first bearer context release completion message is received from the second device for the first bearer context release message.

[0227] In some example embodiments, the first message includes a first identifier of the terminal device assigned by the first apparatus, but does not include a copy indication; and the second message includes a copy indication, the first identifier of the terminal device assigned by the first apparatus, and a second identifier of the terminal device assigned by the second apparatus.

[0228] In some example embodiments, a first device receives a second release request from a first target primary network node or a second target primary network node, the second release request being used to release a secondary network node for switching of a terminal device; and based on multiple target primary network nodes having requested the addition of secondary network nodes, the addition of secondary network nodes being used to prepare one or more secondary target cells for switching of the terminal device, a second bearer context release message is transmitted to a second device, wherein if the second release request is received from the first target primary network node, the second bearer context release message includes a first identifier of the terminal device assigned by the first device and a second identifier of the terminal device assigned by the second device, or, or wherein if the second release request is received from the second target primary network node, the second bearer context release message includes a first identifier of the terminal device assigned by the first device and a third identifier of the terminal device assigned by the second device.

[0229] In some example embodiments, the add request is triggered by the first target master network node in response to: a conditional handover request, or a layer 1 or layer 2 triggered mobility request from a source master network node of the terminal device.

[0230] In some example embodiments, the first device is or is included in a Central Unit-Control Plane (CU-CP) of the secondary network node, and wherein the second device is or is included in a Central Unit-User Plane (CU-UP) of the secondary network node.

[0231] Fig.12 1 is a flowchart of an example method 1200 implemented at a second device according to some example embodiments of the present disclosure. For discussion purposes, the second device (e.g., Figures 4 to 10Method 1200 is described from the perspective of the target SN CU-UP 459).

[0232] At block 1210, a second device receives a request from a secondary network node (eg, Figures 4 to 10 A first device of a target SN CU-CP 458) in the network receives a first message and a second message to reserve resources for a terminal device, the first message including an identifier of a first target master network node and a first identifier of the terminal device assigned by the first device, and the second message including the first identifier of the terminal device and an identifier of the second target master network node, or wherein a copy indication is included in the second message but not in the first message, and the copy indication indicates the copying of the message for the terminal device.

[0233] At block 1220 , the second apparatus determines whether a previous bearer context establishment has been initiated or established for the terminal device based on the first message and the second message.

[0234] At block 1230 , based on a result of the determination, the second device transmits a first response to the first message and a second response to the second message to the first device.

[0235] In some example embodiments, the second device determines, based on a first identifier of the terminal device and an identifier of the first target primary network node included in the first message, that a previous bearer context establishment has not yet been initiated or established for the terminal device; and transmits a first response to the first message to the first device, the first response indicating a first resource reservation for the terminal device.

[0236] In some example embodiments, the second device determines that a previous bearer context establishment has been initiated or established for the terminal device based on a first identifier of the terminal device and an identifier of the second target primary network node included in the second message; and transmits a second response to the second message to the first device, the second response indicating: a first resource reservation for the terminal device as in the first response, or a difference between a second resource reservation for the terminal device in response to the second message and a first resource reservation for the terminal device in response to the first message.

[0237] In some example embodiments, the first message and / or the second message may be a bearer context establishment request or a bearer context modification request. In some example embodiments, the first response and / or the second response may be a bearer context establishment response or a bearer context modification response.

[0238] In some example embodiments, a second device receives a first bearer context release message from a first device, the first bearer context release message including a first identifier of a terminal device and including an identifier of a target primary network node; based on the first bearer context release message, determines that resource reservation for the terminal device is reserved with respect to at least another target primary network node; and transmits a first bearer context release completion message for the first bearer context release message to the second device without releasing the resource reservation for the terminal device.

[0239] In some example embodiments, the first message includes a first identifier of the terminal device assigned by the first device and a second identifier of the terminal device assigned by the second device, without including a copy indication; and wherein the second message includes the first identifier of the terminal device assigned by the first device and the second identifier of the terminal device assigned by the second device, and a copy indication.

[0240] In some example embodiments, the second device determines, based on the first message, that a previous bearer context establishment has not been initiated or established for the terminal device; and transmits a first response to the first message to the first device, the first response indicating a first resource reservation for the terminal device.

[0241] In some example embodiments, if it is determined that the second message includes a copy indication, the second device determines that a previous bearer context establishment has been initiated or established for the terminal device; and transmits a second response to the second message to the first device, the second response indicating: a first resource reservation for the terminal device as in the first response, or a difference between a second resource reservation for the terminal device in response to the second message and a first resource reservation for the terminal device in response to the first message.

[0242] In some example embodiments, the first response includes a second identifier of the terminal device assigned by the second apparatus, and wherein the second response includes a third identifier of the terminal device assigned by the second apparatus, the third identifier being different from the second identifier of the terminal device assigned by the second apparatus.

[0243] In some example embodiments, the second device receives a second bearer context release message from the first device, wherein the second bearer context release message includes a first identifier of the terminal device assigned by the first device and a second identifier of the terminal device assigned by the second device, or wherein the second bearer context release message includes a first identifier of the terminal device assigned by the first device and a third identifier of the terminal device assigned by the second device; based on the second bearer context release message, determines that multiple bearer context establishments have been initiated or established for the terminal device and with respect to multiple primary network nodes; and transmits a second bearer context release completion message for the second bearer context release message to the second device without releasing resource reservation for the terminal device.

[0244] In some example embodiments, the add request is triggered by the first target master network node in response to: a conditional handover request, or a layer 1 or layer 2 triggered mobility request from a source master network node of the terminal device.

[0245] In some example embodiments, the first device is or is included in a Central Unit-Control Plane (CU-CP) of the secondary network node, and wherein the second device is or is included in a Central Unit-User Plane (CU-UP) of the secondary network node.

[0246] Fig.13 1 is a flowchart of an example method 1300 implemented at a first device according to some example embodiments of the present disclosure. For the purpose of discussion, the first device (e.g., Figures 4 to 10 Method 1300 is described from the perspective of the target SN CU-CP 458 in the example.

[0247] At block 1310 , the first apparatus receives an add request for addition of a secondary network node from a first target primary network node, the addition of the secondary network node being used for preparation of one or more secondary target cells for handover of a terminal device.

[0248] At block 1320 , the first apparatus determines whether a previous bearer context establishment has been initiated or established for the terminal device.

[0249] At block 1330 , based at least on a determination that a previous bearer context establishment has been initiated or established for the terminal device, the first apparatus blocks initiation of a message to a second apparatus of the secondary network node to reserve resources for the terminal device.

[0250] At block 1340 , the first apparatus transmits feedback information for the add request to the first target master network node, the feedback information indicating resources reserved for the terminal device by the second apparatus in a previous bearer context establishment.

[0251] In some example embodiments, the first device determines whether resource reservations in a previous bearer context establishment satisfy resource requirements in an add request; and also based on the determination that resource reservations in a previous bearer context establishment satisfy resource requirements in the add request, blocks initiation of a message to a second device of a secondary network node.

[0252] In some example embodiments, upon determining that a previous bearer context establishment has not been initiated or established for the terminal device, the first apparatus transmits to the second apparatus a message including at least an identifier of the terminal device allocated by the first apparatus.

[0253] In some example embodiments, the add request is triggered by the first target master network node in response to: a conditional handover request, or a layer 1 or layer 2 triggered mobility request from a source master network node of the terminal device.

[0254] In some example embodiments, the first device is or is included in a Central Unit-Control Plane (CU-CP) of the secondary network node, and wherein the second device is or is included in a Central Unit-User Plane (CU-UP) of the secondary network node. Example devices, equipment, and media

[0255] In some example embodiments, the first device capable of performing any of the methods 1100 may include a component for performing each operation of the method 1100. The component may be implemented in any suitable form. For example, the component may be implemented in a circuit or a software module.

[0256] In some example embodiments, the first device includes: a component for transmitting a first message to a second device of the secondary network node to reserve resources for a terminal device based on receiving a first add request for adding a secondary network node from a first target primary network node, the addition of the secondary network node being used for preparation of one or more secondary target cells for switching of the terminal device; and a component for transmitting a second message to a second device to reserve resources for the terminal device based on receiving a second add request for adding a secondary network node from a second target primary network node, the addition of the secondary network node being used for preparation of one or more secondary target cells for switching of the terminal device, wherein the first message includes an identifier of the first target primary network node and a first identifier of the terminal device assigned by the first device, and the second message includes the first identifier of the terminal device and an identifier of the second target primary network node, or wherein a copy indication is included in the second message but not in the first message, the copy indication indicating copying of the message for the terminal device.

[0257] In some example embodiments, the first device includes: a component for receiving a first response to a first message from a second device, the first response indicating a first resource reservation for a terminal device; and a component for receiving a second response to a second message from the second device, the second response indicating: the first resource reservation for the terminal device as in the first response, or a difference between the second resource reservation for the terminal device in response to the second message and the first resource reservation for the terminal device in response to the first message.

[0258] In some example embodiments, the first response includes a second identifier of the terminal device assigned by the second apparatus, and wherein the second response includes a third identifier of the terminal device assigned by the second apparatus, the third identifier being different from the second identifier of the terminal device assigned by the second apparatus.

[0259] In some example embodiments, the first device also includes: a component for receiving a first release request from a target primary network node, the first release request being used to release a secondary network node for switching of a terminal device; a component for transmitting a first bearer context release message to a second device if it is determined that multiple target primary network nodes have requested the addition of secondary network nodes, the addition of secondary network nodes being used for preparation of one or more secondary target cells for switching of the terminal device, wherein the first bearer context release message includes a first identifier of the terminal device and an identifier of the target primary network node; and a component for receiving a first bearer context release completion message for the first bearer context release message from the second device.

[0260] In some example embodiments, the first message includes a first identifier of the terminal device assigned by the first apparatus, without including a copy indication; and wherein the second message includes a copy indication, the first identifier of the terminal device assigned by the first apparatus, and the second identifier of the terminal device assigned by the second apparatus.

[0261] In some example embodiments, the first device further comprises: a component for receiving a second release request from a first target primary network node or a second target primary network node, the second release request being used to release a secondary network node for switching of a terminal device; and a component for transmitting a second bearer context release message to a second device based on that multiple target primary network nodes have requested the addition of secondary network nodes, the addition of secondary network nodes being used for preparation of one or more secondary target cells for switching of the terminal device, wherein if the second release request is received from the first target primary network node, the second bearer context release message comprises a first identifier of the terminal device assigned by the first device and a second identifier of the terminal device assigned by the second device, or wherein if the second release request is received from the second target primary network node, the second bearer context release message comprises a first identifier of the terminal device assigned by the first device and a third identifier of the terminal device assigned by the second device.

[0262] In some example embodiments, the add request is triggered by the first target master network node in response to: a conditional handover request, or a layer 1 or layer 2 triggered mobility request from a source master network node of the terminal device.

[0263] In some example embodiments, the first device is or is included in a Central Unit-Control Plane (CU-CP) of the secondary network node, and wherein the second device is or is included in a Central Unit-User Plane (CU-UP) of the secondary network node.

[0264] In some example embodiments, the first apparatus further comprises means for performing other operations in some example embodiments of method 1100. In some example embodiments, the means comprises at least one processor and at least one memory storing instructions which, when executed by the at least one processor, cause the performance of the first apparatus.

[0265] In some example embodiments, the second device capable of performing any of the methods 1200 may include components for performing the various operations of the method 1200. The components may be implemented in any suitable form. For example, the device may be implemented in a circuit or a software module.

[0266] In some example embodiments, the second device includes a component for receiving a first message and a second message from a first device of a secondary network node to reserve resources for a terminal device, wherein the first message includes an identifier of a first target primary network node and a first identifier of the terminal device assigned by the first device, and the second message includes the first identifier of the terminal device and an identifier of the second target primary network node, or wherein a copy indication is included in the second message but not in the first message, the copy indication indicating a copy of a message for the terminal device; a component for determining, based on the first message and the second message, whether a previous bearer context establishment has been initiated or established for the terminal device; and a component for transmitting, based on a result of the determination, a first response to the first message and a second response to the second message to the first device.

[0267] In some example embodiments, the second device also includes: a component for determining that a previous bearer context establishment has not yet been initiated or established for the terminal device based on a first identifier of the terminal device and an identifier of the first target primary network node included in the first message; and a component for transmitting a first response to the first message to the first device, the first response indicating a first resource reservation for the terminal device.

[0268] In some example embodiments, the second device further includes: a component for determining that a previous bearer context establishment has been initiated or established for the terminal device based on a first identifier of the terminal device and an identifier of the second target primary network node included in the second message; and a component for transmitting a second response to the second message to the first device, the second response indicating: a first resource reservation for the terminal device as in the first response, or a difference between a second resource reservation for the terminal device in response to the second message and a first resource reservation for the terminal device in response to the first message.

[0269] In some example embodiments, the second device also includes: a component for receiving a first bearer context release message from the first device, the first bearer context release message including a first identifier of the terminal device and including an identifier of the target primary network node; a component for determining, based on the first bearer context release message, that resource reservation for the terminal device is reserved with respect to at least another target primary network node; and a component for transmitting a first bearer context release completion message for the first bearer context release message to the second device without releasing the resource reservation for the terminal device.

[0270] In some example embodiments, the first message includes a first identifier of the terminal device assigned by the first device and a second identifier of the terminal device assigned by the second device, without including a copy indication; and wherein the second message includes the first identifier of the terminal device assigned by the first device and the second identifier of the terminal device assigned by the second device, and a copy indication.

[0271] In some example embodiments, the second device also includes: a component for determining, based on the first message, that a previous bearer context establishment has not been initiated or established for the terminal device; and a component for transmitting a first response to the first message to the first device, the first response indicating a first resource reservation for the terminal device.

[0272] In some example embodiments, the second device also includes: a component for determining that a previous bearer context establishment has been initiated or established for the terminal device if it is determined that the second message includes a copy indication; and a component for transmitting a second response to the second message to the first device, the second response indicating: a first resource reservation for the terminal device as in the first response, or a difference between a second resource reservation for the terminal device in response to the second message and a first resource reservation for the terminal device in response to the first message.

[0273] In some example embodiments, the first response includes a second identifier of the terminal device assigned by the second apparatus, and wherein the second response includes a third identifier of the terminal device assigned by the second apparatus, the third identifier being different from the second identifier of the terminal device assigned by the second apparatus.

[0274] In some example embodiments, the second device further includes: a component for receiving a second bearer context release message from the first device, wherein the second bearer context release message includes a first identifier of the terminal device assigned by the first device and a second identifier of the terminal device assigned by the second device, or, wherein the second bearer context release message includes a first identifier of the terminal device assigned by the first device and a third identifier of the terminal device assigned by the second device; a component for determining, based on the second bearer context release message, that multiple bearer context establishments have been initiated or established for the terminal device and with respect to multiple primary network nodes; and a component for transmitting a second bearer context release completion message for the second bearer context release message to the second device without releasing resource reservation for the terminal device.

[0275] In some example embodiments, the add request is triggered by the first target master network node in response to: a conditional handover request, or a layer 1 or layer 2 triggered mobility request from a source master network node of the terminal device.

[0276] In some example embodiments, the first device is or is included in a Central Unit-Control Plane (CU-CP) of the secondary network node, and wherein the second device is or is included in a Central Unit-User Plane (CU-UP) of the secondary network node.

[0277] In some example embodiments, the second apparatus further comprises means for performing other operations in some example embodiments of method 1200. In some example embodiments, the means comprises at least one processor and at least one memory storing instructions which, when executed by the at least one processor, cause the performance of the second apparatus.

[0278] In some example embodiments, the first device includes: a component for receiving an addition request for adding a secondary network node from a first target primary network node, the addition of the secondary network node being used for preparation of one or more secondary target cells for switching of a terminal device; a component for determining whether a previous bearer context establishment has been initiated or established for the terminal device; a component for preventing initiation of a message to a second device of the secondary network node to reserve resources for the terminal device based at least on a determination that a previous bearer context establishment has been initiated or established for the terminal device; and a component for transmitting feedback information for the addition request to the first target primary network node, the feedback information indicating resource reservation for the terminal device by the second device in the previous bearer context establishment.

[0279] In some example embodiments, the first device further comprises: a component for determining whether a resource reservation in a previous bearer context establishment satisfies a resource requirement in an add request; and a component for preventing initiation of a message to a second device of the secondary network node, also based on a determination that a resource reservation in a previous bearer context establishment satisfies a resource requirement in the add request.

[0280] In some example embodiments, the first apparatus further comprises means for transmitting to the second apparatus a message comprising at least an identifier of the terminal device allocated by the first apparatus if it is determined that a previous bearer context establishment has not been initiated or established for the terminal device.

[0281] In some example embodiments, the add request is triggered by the first target master network node in response to: a conditional handover request, or a layer 1 or layer 2 triggered mobility request from a source master network node of the terminal device.

[0282] In some example embodiments, the first device is or is included in a Central Unit-Control Plane (CU-CP) of the secondary network node, and wherein the second device is or is included in a Central Unit-User Plane (CU-UP) of the secondary network node.

[0283] In some example embodiments, the first apparatus further comprises means for performing other operations in some example embodiments of method 1300. In some example embodiments, the means comprises at least one processor and at least one memory storing instructions which, when executed by the at least one processor, cause the performance of the first apparatus.

[0284] Fig.14 14 is a simplified block diagram of a device 1400 suitable for implementing an example embodiment of the present disclosure. The device 1400 may be provided to implement a communication device, such as a first device or a second device. As shown, the device 1400 includes one or more processors 1410, one or more memories 1420 coupled to the processor 1410, and one or more communication modules 1440 coupled to the processor 1410.

[0285] The communication module 1440 is used for two-way communication. The communication module 1440 has one or more communication interfaces to facilitate communication with one or more other modules or devices. The communication interface may represent any interface necessary for communication with other network elements. In some example embodiments, the communication module 1440 may include at least one antenna.

[0286] Processor 1410 may be of any type suitable for the local technology network and may include one or more of the following: a general purpose computer, a special purpose computer, a microprocessor, a digital signal processor (DSP), and a processor based on a multi-core processor architecture, as non-limiting examples. Device 1400 may have multiple processors, such as application specific integrated circuit chips that are time slaved to a clock that synchronizes a main processor.

[0287] The memory 1420 may include one or more non-volatile memories and one or more volatile memories. Examples of non-volatile memories include, but are not limited to, read-only memory (ROM) 1424, electrically programmable read-only memory (EPROM), flash memory, hard disk, compact disk (CD), digital video disk (DVD), optical disk, laser disk, and other magnetic and / or optical memories. Examples of volatile memories include, but are not limited to, random access memory (RAM) 1422 and other volatile memories that do not last for the duration of a power outage.

[0288] The computer program 1430 includes computer executable instructions executed by the associated processor 1410. The instructions of the program 1430 may include instructions for performing the operations / actions of some example embodiments of the present disclosure. The program 1430 may be stored in a memory such as ROM 1424. The processor 1410 may perform any suitable actions and processes by loading the program 1430 into the RAM 1422.

[0289] The exemplary embodiments of the present disclosure may be implemented by the program 1430 so that the device 1400 may execute the Figures 4 to 13 Any process of the present disclosure discussed. Example embodiments of the present disclosure may also be implemented by hardware or a combination of software and hardware.

[0290] In some example embodiments, the program 1430 may be tangibly embodied in a computer-readable medium, which may be contained in the device 1400 (e.g., in the memory 1420) or in other storage devices accessible to the device 1400. The device 1400 may load the program 1430 from the computer-readable medium to the RAM 1422 for execution. In some example embodiments, the computer-readable medium may include any type of non-transitory storage medium, such as ROM, EPROM, flash memory, hard disk, CD, DVD, etc. The term "non-transitory" as used herein is a limitation of the medium itself (i.e., tangible, not a signal), versus a limitation on data storage persistence (e.g., RAM vs. ROM).

[0291] Fig.15 An example of a computer readable medium 1500 is shown, which may be in the form of a CD, DVD, or other optical storage disk. The computer readable medium 1500 has a program 1430 stored thereon.

[0292] Generally, various embodiments of the present disclosure may be implemented in hardware or dedicated circuits, software, logic, or any combination thereof. Some aspects may be implemented in hardware, and other aspects may be implemented in firmware or software, which may be executed by a controller, microprocessor, or other computing device. Although various aspects of the embodiments of the present disclosure are illustrated and described as block diagrams, flow charts, or using some other graphical representations, it should be understood that, as non-limiting examples, the blocks, devices, systems, techniques, or methods described herein may be implemented in hardware, software, firmware, dedicated circuits or logic, general hardware or controllers or other computing devices, or some combination thereof.

[0293] Some example embodiments of the present disclosure also provide at least one computer program product tangibly stored on a computer-readable medium (such as, non-volatile computer-readable medium). The computer program product includes computer executable instructions, such as those computer executable instructions executed in a device on a target physical or virtual processor included in a program module, to perform any method as above. Typically, a program module includes routines, programs, libraries, objects, classes, components, data structures, etc. that perform specific tasks or implement specific abstract data types. The functionality of a program module can be combined or split between program modules as needed in different embodiments. Machine executable instructions for program modules can be executed in local or distributed devices. In distributed devices, program modules can be located in local and remote storage media.

[0294] The program code for performing the method of the present disclosure may be written in any combination of one or more programming languages. The program code may be provided to a processor or controller of a general-purpose computer, a special-purpose computer, or other programmable data processing device so that the program code, when executed by the processor or controller, causes the implementation of the functions / operations specified in the flow chart and / or block diagram. The program code may be executed entirely on the machine, partially on the machine, as an independent software package, partially on the machine, partially on a remote machine, or entirely on a remote machine or server.

[0295] In the context of the present disclosure, computer program codes or related data may be carried by any suitable carrier to enable a device, apparatus or processor to perform the above different processes and operations. Examples of carriers include signals, computer readable media, etc.

[0296] The computer readable medium may be a computer readable signal medium or a computer readable storage medium. The computer readable medium may include, but is not limited to, electronic, magnetic, optical, electromagnetic, infrared, or semiconductor systems, devices, or devices, or any suitable combination of the foregoing. More specific examples of computer readable storage media will include an electrical connection with one or more wires, a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.

[0297] Further, although the operations are depicted in a particular order, this should not be construed as requiring the execution of such operations in the particular order shown or in a sequential order, or the execution of all described operations, to achieve the desired result. In some cases, multitasking and parallel processing may be advantageous. Similarly, although several specific implementation details are included in the above discussion, these should not be construed as limitations on the scope of the present disclosure, but rather as descriptions of features that may be specific to a particular embodiment. Unless explicitly stated, certain features described in the context of a separate embodiment may also be implemented in combination in a single embodiment. On the contrary, unless explicitly stated, the different features described in the context of a single embodiment may also be implemented in multiple embodiments individually or in any suitable subcombination.

[0298] Although the disclosure has been described in language specific to structural features and / or methodological actions, it is to be understood that the disclosure defined in the appended claims is not necessarily limited to the specific features or actions described above. Instead, the specific features and actions described above are disclosed as example forms of implementing the claims.

[0299] Some abbreviations used in this disclosure are provided below, where they are represented in unshortened form. It should be noted that widely established and unique abbreviations may be assumed to be known.

[0300] In some aspects, a first apparatus is provided, comprising: at least one processor; and at least one memory, the at least one memory storing instructions, which when executed by the at least one processor, cause the first device to at least perform: Based on receiving a first add request for adding a secondary network node from the first target primary network node, the adding of the secondary network node is used for preparing one or more secondary target cells for handover of the terminal device, transmitting a first message to a second device of the secondary network node to reserve resources for the terminal device; and transmitting a second message to the second device to reserve resources for the terminal device based on receiving a second addition request for adding a secondary network node from the second target primary network node, the addition of the secondary network node being used for preparation of one or more secondary target cells for handover of the terminal device, wherein the first message includes an identifier of a first target master network node and a first identifier of a terminal device assigned by the first apparatus, and the second message includes the first identifier of the terminal device and an identifier of a second target master network node, or The copy indication is included in the second message but not in the first message, and the copy indication indicates copying of the message to the terminal device.

[0301] In some aspects, the first device is also caused to perform: receiving a first response to the first message from the second device, the first response indicating a first resource reservation for the terminal device; and receiving a second response to the second message from the second device, the second response indicating: the first resource reservation for the terminal device as in the first response, or the difference between the second resource reservation for the terminal device in response to the second message and the first resource reservation for the terminal device in response to the first message.

[0302] In some aspects, the first response includes a second identifier of the terminal device assigned by the second apparatus, and the second response includes a third identifier of the terminal device assigned by the second apparatus, the third identifier being different from the second identifier of the terminal device assigned by the second apparatus.

[0303] In some aspects, the first device is also caused to execute: receiving a first release request from a target primary network node, the first release request being used to release a secondary network node used for switching of a terminal device; if it is determined that multiple target primary network nodes have requested the addition of secondary network nodes, the addition of secondary network nodes is used to prepare one or more secondary target cells for switching of the terminal device, transmitting a first bearer context release message to a second device, wherein the first bearer context release message includes a first identifier of the terminal device and an identifier of the target primary network node; and receiving a first bearer context release completion message for the first bearer context release message from the second device.

[0304] In some aspects, the first message includes a first identifier of the terminal device assigned by the first device without including a copy indication; and the second message includes a copy indication, the first identifier of the terminal device assigned by the first device, and the second identifier of the terminal device assigned by the second device.

[0305] In some aspects, the first device is also caused to perform: receiving a second release request from the first target primary network node or the second target primary network node, the second release request being used to release a secondary network node used for switching of the terminal device; and transmitting a second bearer context release message to the second device based on the addition of secondary network nodes requested by multiple target primary network nodes, the addition of secondary network nodes being used to prepare one or more secondary target cells for switching of the terminal device, wherein if the second release request is received from the first target primary network node, the second bearer context release message includes a first identifier of the terminal device assigned by the first device and a second identifier of the terminal device assigned by the second device, or wherein if the second release request is received from the second target primary network node, the second bearer context release message includes a first identifier of the terminal device assigned by the first device and a third identifier of the terminal device assigned by the second device.

[0306] In some aspects, wherein the add request is triggered by the first target master network node in response to: a conditional handover request, or a layer 1 or layer 2 triggered mobility request from a source master network node of the terminal device.

[0307] In some aspects, wherein the first device is or is included in a Central Unit-Control Plane (CU-CP) of the secondary network node, and wherein the second device is or is included in a Central Unit-User Plane (CU-UP) of the secondary network node.

[0308] In some aspects, a second apparatus is provided, comprising: at least one processor; and at least one memory, the at least one memory storing instructions, which when executed by the at least one processor, cause the second device to at least perform: A first device of a secondary network node receives a first message and a second message to prepare a terminal device Retain resources; wherein the first message includes an identifier of a first target master network node and a first identifier of a terminal device assigned by the first apparatus, and the second message includes the first identifier of the terminal device and an identifier of a second target master network node, or wherein the copy indication is included in the second message but not in the first message, the copy indication indicating copying of the message for the terminal device; determining, based on the first message and the second message, whether a previous bearer context establishment has been initiated or established for the terminal device; and Based on a result of the determination, a first response to the first message and a second response to the second message are transmitted to the first device.

[0309] In some aspects, the second device is also caused to perform: determining that a previous bearer context establishment has not yet been initiated or established for the terminal device based on a first identifier of the terminal device and an identifier of the first target primary network node included in the first message; and transmitting a first response to the first message to the first device, the first response indicating a first resource reservation for the terminal device.

[0310] In some aspects, the second device is caused to perform: determining that a previous bearer context establishment has been initiated or established for the terminal device based on a first identifier of the terminal device and an identifier of the second target primary network node included in the second message; and transmitting a second response to the second message to the first device, the second response indicating: a first resource reservation for the terminal device as in the first response, or a difference between the second resource reservation for the terminal device in response to the second message and the first resource reservation for the terminal device in response to the first message.

[0311] In some aspects, the second device is also caused to perform: receiving a first bearer context release message from the first device, the first bearer context release message including a first identifier of the terminal device and including an identifier of the target primary network node; based on the first bearer context release message, determining that resource reservation for the terminal device is reserved for at least another target primary network node; and transmitting a first bearer context release completion message for the first bearer context release message to the second device without releasing the resource reservation for the terminal device.

[0312] In some aspects, the first message includes a first identifier of the terminal device assigned by the first device and a second identifier of the terminal device assigned by the second device, without including a copy indication; and the second message includes the first identifier of the terminal device assigned by the first device and the second identifier of the terminal device assigned by the second device, and a copy indication.

[0313] In some aspects, the second device is also caused to perform: based on the first message, determine that a previous bearer context establishment has not been initiated or established for the terminal device; and transmit a first response to the first message to the first device, the first response indicating a first resource reservation for the terminal device.

[0314] In some aspects, the second device is caused to perform: if it is determined that the second message includes a copy indication, determine that a previous bearer context establishment has been initiated or established for the terminal device; and transmit a second response to the second message to the first device, the second response indicating: the first resource reservation for the terminal device as in the first response, or the difference between the second resource reservation for the terminal device in response to the second message and the first resource reservation for the terminal device in response to the first message.

[0315] In some aspects, the first response includes a second identifier of the terminal device assigned by the second apparatus, and the second response includes a third identifier of the terminal device assigned by the second apparatus, the third identifier being different from the second identifier of the terminal device assigned by the second apparatus.

[0316] In some aspects, the second device is also caused to perform: receiving a second bearer context release message from the first device, wherein the second bearer context release message includes a first identifier of the terminal device assigned by the first device and a second identifier of the terminal device assigned by the second device, or wherein the second bearer context release message includes a first identifier of the terminal device assigned by the first device and a third identifier of the terminal device assigned by the second device; based on the second bearer context release message, determining that multiple bearer context establishments have been initiated or established for the terminal device and with respect to multiple primary network nodes; and transmitting a second bearer context release completion message for the second bearer context release message to the second device without releasing resource reservation for the terminal device.

[0317] In some aspects, wherein the add request is triggered by the first target master network node in response to: a conditional handover request, or a layer 1 or layer 2 triggered mobility request from a source master network node of the terminal device.

[0318] In some aspects, wherein the first device is or is included in a Central Unit-Control Plane (CU-CP) of the secondary network node, and wherein the second device is or is included in a Central Unit-User Plane (CU-UP) of the secondary network node.

[0319] In some aspects, a first apparatus is provided, comprising: at least one processor; and at least one memory, the at least one memory storing instructions, which when executed by the at least one processor, cause the first device to at least perform: receiving, from the first target primary network node, an adding request for adding a secondary network node, the adding of the secondary network node being used for preparation of one or more secondary target cells for handover of the terminal device; determining whether a previous bearer context establishment has been initiated or established for the terminal device; based at least on a determination that a previous bearer context establishment has been initiated or established for the terminal device, preventing initiation of a message to the second apparatus of the secondary network node to reserve resources for the terminal device; and Feedback information for the add request is transmitted to the first target master network node, the feedback information indicating resources reserved for the terminal device by the second apparatus in a previous bearer context establishment.

[0320] In some aspects, the first device is also caused to: determine whether the resource reservation in the previous bearer context establishment satisfies the resource requirements in the add request; and prevent initiating a message to the second device of the secondary network node based on the determination that the resource reservation in the previous bearer context establishment satisfies the resource requirements in the add request.

[0321] In some aspects, the first apparatus is further caused to: if it is determined that a previous bearer context establishment has not been initiated or established for the terminal device, transmit a message including at least an identifier of the terminal device allocated by the first apparatus to the second apparatus.

[0322] In some aspects, wherein the add request is triggered by the first target master network node in response to: a conditional handover request, or a layer 1 or layer 2 triggered mobility request from a source master network node of the terminal device.

[0323] In some aspects, wherein the first device is or is included in a Central Unit-Control Plane (CU-CP) of the secondary network node, and wherein the second device is or is included in a Central Unit-User Plane (CU-UP) of the secondary network node.

[0324] In some aspects, a method is provided, comprising: Based on receiving at the first device and from the first target primary network node a first add request for addition of a secondary network node, the addition of the secondary network node being used for preparation of one or more secondary target cells for handover of the terminal device, transmitting a first message to a second device of the secondary network node to reserve resources for the terminal device; and transmitting a second message to the second device to reserve resources for the terminal device based on receiving a second addition request for adding a secondary network node from the second target primary network node, the addition of the secondary network node being used for preparation of one or more secondary target cells for handover of the terminal device, wherein the first message includes an identifier of a first target master network node and a first identifier of a terminal device assigned by the first apparatus, and the second message includes the first identifier of the terminal device and an identifier of a second target master network node, or The copy indication is included in the second message but not in the first message, and the copy indication indicates copying of the message to the terminal device.

[0325] In some aspects, a method is provided, comprising: receiving, at the second device and from the first device of the secondary network node, a first message and a second message to reserve resources for the terminal device, wherein the first message includes an identifier of a first target master network node and a first identifier of a terminal device assigned by the first apparatus, and the second message includes the first identifier of the terminal device and an identifier of a second target master network node, or wherein the copy indication is included in the second message but not in the first message, the copy indication indicating copying of the message for the terminal device; determining, based on the first message and the second message, whether a previous bearer context establishment has been initiated or established for the terminal device; and Based on a result of the determination, a first response to the first message and a second response to the second message are transmitted to the first device.

[0326] In some aspects, a method is provided, comprising: receiving, at the first apparatus and from the first target primary network node, an add request for addition of a secondary network node, the addition of the secondary network node being used for preparation of one or more secondary target cells for handover of the terminal device; determining whether a previous bearer context establishment has been initiated or established for the terminal device; based at least on a determination that a previous bearer context establishment has been initiated or established for the terminal device, preventing initiation of a message to the second apparatus of the secondary network node to reserve resources for the terminal device; and Feedback information for the add request is transmitted to the first target master network node, the feedback information indicating resources reserved for the terminal device by the second apparatus in a previous bearer context establishment.

[0327] In some aspects, a first apparatus is provided, comprising: means for transmitting a first message to a second device of the secondary network node to reserve resources for the terminal device based on receiving a first add request for addition of a secondary network node from the first target primary network node, the addition of the secondary network node being used for preparation of one or more secondary target cells for handover of the terminal device; and means for transmitting a second message to a second device to reserve resources for the terminal device based on receiving a second addition request for addition of a secondary network node from a second target primary network node, the addition of the secondary network node being used for preparation of one or more secondary target cells for handover of the terminal device, wherein the first message includes an identifier of a first target master network node and a first identifier of a terminal device assigned by the first apparatus, and the second message includes the first identifier of the terminal device and an identifier of a second target master network node, or The copy indication is included in the second message but not in the first message, and the copy indication indicates copying of the message to the terminal device.

[0328] In some aspects, a second apparatus is provided, comprising: means for receiving a first message and a second message from a first device of a secondary network node to reserve resources for a terminal device, wherein the first message includes an identifier of a first target master network node and a first identifier of a terminal device assigned by the first apparatus, and the second message includes the first identifier of the terminal device and an identifier of a second target master network node, or wherein the copy indication is included in the second message but not in the first message, the copy indication indicating copying of the message for the terminal device; means for determining, based on the first message and the second message, whether a previous bearer context establishment has been initiated or established for the terminal device; and Means for transmitting, based on a result of the determining, a first response to the first message and a second response to the second message to the first device.

[0329] In some aspects, a first apparatus is provided, comprising: means for receiving, from the first target primary network node, an addition request for addition of a secondary network node, the addition of the secondary network node being used for preparation of one or more secondary target cells for handover of the terminal device; means for determining whether a previous bearer context establishment has been initiated or established for a terminal device; means for preventing initiation of a message to the second apparatus of the secondary network node to reserve resources for the terminal device based at least on a determination that a previous bearer context establishment has been initiated or established for the terminal device; and A means for transmitting feedback information for the add request to the first target primary network node, the feedback information indicating resources reserved for the terminal device by the second apparatus in a previous bearer context establishment.

[0330] In some aspects, a computer-readable medium is provided, comprising instructions stored thereon, the instructions being used to cause an apparatus to at least perform a method according to any one of the above items. List of abbreviations CHO-Conditional Handover CU-CP-Central Unit Control Plane Central Unit Control Plane CU-UP-Central Unit User Plane Central Unit User Plane DC-Dual Connectivity DRB-Data Radio Bearer Data Radio Bearer HO - Handover MN-Master Node NR-New Radio New Radio Technology PCell-Primary Cell PSCell-Primary Secondary Cell SCG-Secondary Cell Group SN-Secondary Node TEID-Tunnel Endpoint Identifier Tunnel endpoint identifier LTM – L1 / L2 Triggered Mobility

Claims

1. A first device for communication, comprising: at least one processor; as well as at least one memory storing instructions that, when executed by the at least one processor, cause the first device to at least perform: based on receiving a first adding request for adding a secondary network node from the first target primary network node, the adding of the secondary network node being used for preparation of one or more secondary target cells for handover of the terminal device, transmitting a first message to a second device of the secondary network node to reserve resources for the terminal device; as well as transmitting a second message to the second apparatus to reserve resources for the terminal device based on receiving a second addition request for adding the secondary network node from the second target primary network node, the addition of the secondary network node being used for preparation of one or more secondary target cells for handover of the terminal device, wherein the first message includes an identifier of the first target master network node and a first identifier of the terminal device assigned by the first apparatus, and the second message includes the first identifier of the terminal device and an identifier of the second target master network node, or The copy indication is included in the second message but not in the first message, and the copy indication indicates copying of the message for the terminal device.

2. The apparatus according to claim 1, wherein the first device is further caused to execute: receiving a first response to the first message from the second apparatus, the first response indicating a first resource reservation for the terminal device; and A second response to the second message is received from the second device, the second response indicating: as the first resource reservation for the terminal device in the first response, or a difference between a second resource reservation for the terminal device in response to the second message and the first resource reservation for the terminal device in response to the first message.

3. The apparatus according to claim 2, wherein the first response comprises a second identifier of the terminal device assigned by the second apparatus, and The second response includes a third identifier of the terminal device assigned by the second apparatus, and the third identifier is different from the second identifier of the terminal device assigned by the second apparatus.

4. The apparatus according to claim 1, wherein the first device is further caused to execute: receiving a first release request from a target primary network node, the first release request being used to release the secondary network node used for handover of the terminal device; if it is determined that a plurality of target primary network nodes have requested the addition of the secondary network node, the addition of the secondary network node being used for preparation of one or more secondary target cells for the handover of the terminal device, transmitting a first bearer context release message to the second apparatus, wherein the first bearer context release message includes a first identifier of the terminal device and an identifier of the target primary network node; and A first bearer context release complete message is received from the second device in response to the first bearer context release message.

5. The apparatus according to claim 1, wherein the first message includes the first identifier of the terminal device assigned by the first apparatus, but does not include the copy indication; and The second message includes the copy indication, the first identifier of the terminal device assigned by the first apparatus, and the second identifier of the terminal device assigned by the second apparatus.

6. The apparatus according to claim 5, wherein the first device is further caused to execute: receiving a second release request from the first target primary network node or the second target primary network node, the second release request being used to release the secondary network node used for handover of the terminal device; and transmitting a second bearer context release message to the second device according to multiple target primary network nodes having requested the addition of the secondary network node, the addition of the secondary network node being used for preparation of one or more secondary target cells for the handover of the terminal device, wherein if the second release request is received from the first target primary network node, the second bearer context release message includes the first identifier of the terminal device allocated by the first apparatus and the second identifier of the terminal device allocated by the second apparatus, or Wherein if the second release request is received from the second target primary network node, the second bearer context release message includes the first identifier of the terminal equipment allocated by the first device and the third identifier of the terminal equipment allocated by the second device.

7. The apparatus of claim 1, wherein the add request is triggered by the first target master network node in response to: a conditional handover request, or a layer 1 or layer 2 triggered mobility request from a source master network node of the terminal device.

8. The apparatus according to any one of claims 1 to 7, wherein the first apparatus is or is included in a Central Unit-Control Plane (CU-CP) of the secondary network node, and The second device is or is included in a Central Unit-User Plane (CU-UP) of the secondary network node.

9. A method for communication, comprising: based on receiving at the first device and from the first target primary network node a first add request for addition of a secondary network node, the addition of the secondary network node being used for preparation of one or more secondary target cells for handover of the terminal device, transmitting a first message to a second device of the secondary network node to reserve resources for the terminal device; as well as transmitting a second message to the second apparatus to reserve resources for the terminal device based on receiving a second addition request for adding the secondary network node from the second target primary network node, the addition of the secondary network node being used for preparation of one or more secondary target cells for handover of the terminal device, wherein the first message includes an identifier of the first target master network node and a first identifier of the terminal device assigned by the first apparatus, and the second message includes the first identifier of the terminal device and an identifier of the second target master network node, or The copy indication is included in the second message but not in the first message, and the copy indication indicates copying of the message for the terminal device.

10. A first device for communication, comprising: means for transmitting a first message to a second device of the secondary network node to reserve resources for the terminal device based on receiving a first add request for addition of a secondary network node from the first target primary network node, the addition of the secondary network node being used for preparation of one or more secondary target cells for handover of the terminal device; as well as means for transmitting a second message to the second apparatus to reserve resources for the terminal device based on receiving a second addition request for addition of the secondary network node from a second target primary network node, the addition of the secondary network node being used for preparation of one or more secondary target cells for handover of the terminal device, wherein the first message includes an identifier of the first target master network node and a first identifier of the terminal device assigned by the first apparatus, and the second message includes the first identifier of the terminal device and an identifier of the second target master network node, or The copy indication is included in the second message but not in the first message, and the copy indication indicates copying of the message for the terminal device.

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