User equipment, network equipment, user equipment method, and network equipment method

Abstract

[0003] Embodiments of the present disclosure relate to a communication method, an apparatus, and a computer-readable medium. In one aspect, when it is determined that a subsequent conditional cell change is to be performed from a source cell to a target cell, a terminal device performs a first set of procedures including at least one of updating security keys associated with the target cell, performing PDCP re-establishment for DRBs and SRBs, or performing RLC re-establishment for the DRBs and SRBs. In this way, UE behavior for supporting selective activation of cell groups is defined.

Description

[Technical Field]

[0001] FIELD Embodiments of the present disclosure relate generally to the field of telecommunications, and more particularly to communication methods, apparatus, and computer storage media for selective activation of cell groups. [Background technology]

[0002] Currently, Multi-Random access technology Dual Connectivity (MR-DC) with selective activation of cell groups aims to enable subsequent conditional primary secondary cell (PSCell) change (CPC) after a secondary cell group (SCG) change without reconfiguration and reinitialization during conditional PSCell change (CPC) / conditional PSCell addition (CPA) preparation from the network side. This reduces the signaling overhead and interruption time for SCG change. However, the solution for subsequent CPC / CPA after a CPC / CPA procedure is still incomplete and needs further research. Summary of the Invention [Problem to be solved by the invention]

[0003] Generally, embodiments of the present disclosure provide a communication method, apparatus, and computer storage medium for selective activation of cell groups. [Means for solving the problem]

[0004] In a first aspect, a method of communication is provided, the method including: determining, in a terminal device, that a subsequent conditional cell change is to be performed from a source cell to a target cell; and performing a first set of procedures including at least one of updating security keys associated with the target cell, performing Packet Data Convergence Protocol (PDCP) re-establishment for Data Radio Bearers (DRBs) and Signaling Radio Bearers (SRBs), or performing Radio Link Control (RLC) re-establishment for the DRBs and the SRBs.

[0005] In a second aspect, a method of communication is provided, the method including: receiving, at a first network device, a message from a terminal device indicating that a conditional cell change is to be performed from a source cell to a target cell; and sending, to a second network device providing the source cell, an indication indicating release of a connection with the terminal device.

[0006] In a third aspect, a method of communication is provided, the method including: determining in a first network device that a configuration for a subsequent conditional cell addition or modification is to be released; and sending an indication indicating the release of the configuration for the subsequent conditional cell addition or modification to a second network device that provides a candidate cell for the subsequent conditional cell addition or modification.

[0007] In a fourth aspect, there is provided a communications apparatus, the apparatus comprising a processor configured to cause the apparatus to perform a method according to any one of the first to third aspects of the present disclosure.

[0008] In a fifth aspect, there is provided a computer-readable medium storing instructions that, when executed on at least one processor, cause the at least one processor to perform a method according to any one of the first to third aspects of the present disclosure.

[0009] Other features of the present disclosure will be readily apparent from the following description. [Brief explanation of the drawings]

[0010] The above and other objects, features and advantages of the present disclosure will become more apparent from the following detailed description of several embodiments of the present disclosure in the accompanying drawings.

[0011] [Figure 1A] FIG. 1 illustrates an exemplary communication network in which some embodiments of the present disclosure may be implemented.

[0012] [Figure 1B] 1 is a schematic diagram illustrating network protocol layer entities that may be established for a User Plane (UP) protocol stack in an apparatus according to some embodiments of the present disclosure. FIG.

[0013] [Figure 1C] 1 is a schematic diagram illustrating network protocol layer entities that may be established for a control plane (CP) protocol stack in an apparatus according to some embodiments of the present disclosure. FIG.

[0014] [Figure 2] FIG. 1 is a schematic diagram illustrating an exemplary communication process according to an embodiment of the present disclosure.

[0015] [Figure 3] FIG. 10 is a schematic diagram illustrating another exemplary communication process according to an embodiment of the present disclosure.

[0016] [Figure 4]FIG. 10 is a schematic diagram illustrating yet another exemplary communication process according to an embodiment of the present disclosure.

[0017] [Figure 5] FIG. 1 illustrates an exemplary communication method implemented in a terminal device, according to some embodiments of the present disclosure.

[0018] [Figure 6] FIG. 2 illustrates an exemplary communication method implemented in a network device, according to some embodiments of the present disclosure.

[0019] [Figure 7] FIG. 1 illustrates another exemplary communication method implemented in a network device, in accordance with some embodiments of the present disclosure.

[0020] [Figure 8] FIG. 1 is a schematic block diagram of an apparatus suitable for implementing embodiments of the present disclosure.

[0021] In the figures, the same or similar reference symbols represent the same or similar elements. DETAILED DESCRIPTION OF THE INVENTION

[0022] The principles of the present disclosure will now be described with reference to some embodiments. It should be understood that these embodiments are provided for illustrative purposes only to aid those skilled in the art in understanding and practicing the present disclosure, and do not imply any limitation on the scope of the present disclosure. The disclosure described herein can be implemented in various ways different from those described below.

[0023] 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.

[0024] As used herein, the term "terminal device" refers to any device with wireless or wired communication capabilities. Examples of terminal devices include User Equipment (UE), personal computers, desktops, mobile phones, cellular phones, smartphones, Personal Digital Assistants (PDAs), portable computers, tablets, wearable devices, Internet of Things (IoT) devices, Ultra-reliable and Low Latency Communication (URLLC) devices, Internet of Everything (IoE) devices, Machine Type Communication (MTC) devices, vehicle-mounted devices for V2X communications where X stands for pedestrian, vehicle, or infrastructure / network, devices for Integrated Access and Backhaul (IAB), satellite- or airborne vehicles in a Non-Terrestrial Network (NTN) including High Altitude Platforms (HAPs) including satellites and Unmanned Aircraft Systems (UASs), Augmented Reality (AR), Mixed Reality (MR), and other technologies. This includes, but is not limited to, extended reality (XR) devices that include different types of reality, such as real world reality (VR), virtual reality (VR), unmanned aerial vehicles (UAVs), which are aircraft without a human pilot and are commonly referred to as drones, devices on high speed trains (HST), image capture devices such as digital cameras, sensors, gaming devices, music storage and playback devices, or internet devices that enable wireless or wired internet access and browsing.The "terminal device" may further have "multicast / broadcast" capabilities to support public safety and mission-critical V2X applications, transparent IPv4 / IPv6 multicast distribution, IPTV, smart TV, wireless services, over-the-air software distribution, group communication, and IoT applications. It may also incorporate one or more Subscriber Identity Modules (SIMs), known as multi-SIMs. The term "terminal device" may be used interchangeably with UE, mobile station, subscriber station, mobile terminal, user terminal, or wireless device.

[0025] The term "network device" as used herein means a device capable of providing or hosting a cell or coverage area in which a terminal device can communicate. Examples of network devices include, but are not limited to, a Node B (Node B or NB), an evolved Node B (eNode B or eNB), a next generation Node B (gNB), a Transmission Reception Point (TRP), a Remote Radio Unit (RRU), a Radio Head (RH), a Remote Radio Head (RRH), an IAB node, a low-power node such as a femto node or a pico node, a Reconfigurable Intelligent Surface (RIS), etc.

[0026] A terminal device or a network device may have the capability of artificial intelligence (AI) or machine learning, which generally includes a model trained from a large amount of data collected for a specific function and can be used to predict some information.

[0027] The terminal device or network device may operate on several frequency ranges, such as FR1 (410 MHz to 7125 MHz), FR2 (24.25 GHz to 71 GHz), frequency bands greater than 100 GHz, and Terahertz (THz). It can also operate on licensed, unlicensed, and shared spectrum. The terminal device may have two or more connections with the network device under a Multi-Radio Dual Connectivity (MR-DC) application scenario. The terminal device or network device can operate in full duplex, flexible duplex, and cross-division duplex modes.

[0028] Embodiments of the present disclosure may be implemented in test equipment, such as, for example, a signal generator, a signal analyzer, a spectrum analyzer, a network analyzer, a test terminal device, a test network device, a channel emulator, and the like.

[0029] In one embodiment, a terminal device may be connected to a first network device and a second network device. One of the first network device and the second network device may be a master node, and the other may be a secondary node. The first network device and the second network device may use different radio access technologies (RATs). In one embodiment, the first network device may be a first RAT device, and the second network device may be a second RAT device. In one embodiment, the first RAT device is an eNB, and the second RAT device is a gNB. Information regarding the different RATs may be transmitted to the terminal device from at least one of the first network device or the second network device. In one embodiment, the first information may be transmitted from the first network device to the terminal device, and the second information may be transmitted from the second network device directly or via the first network device to the terminal device. In one embodiment, information regarding the terminal device configuration configured by the second network device may be transmitted from the second network device via the first network device. Information regarding the reconfiguration of the terminal device configured by the second network device may be transmitted to the terminal device directly from the second network device or via the first network device.

[0030] As used herein, the singular forms "a," "an," and "said" include the plural forms unless the context clearly indicates otherwise. The term "comprises" and variations thereof should be understood as open-ended terms meaning "including, but not limited to." The term "based on" should be understood as "based at least in part on." The terms "one embodiment" and "embodiment" should be understood as "at least one embodiment." The term "another embodiment" should be understood as "at least one other embodiment." Terms such as "first," "second," etc. may refer to different or the same object. The following may include other explicit and implicit definitions.

[0031] In some instances, values, procedures, or devices are referred to as "best," "lowest," "highest," "minimum," "maximum," etc. It should be understood that such descriptions are intended to illustrate that selections may be made from among many functional alternatives used, and that such selections are not necessarily better, smaller, higher, or otherwise more preferred than other selections.

[0032] In the context of this application, the term "selective activation of a cell group" may be used interchangeably with "subsequent CPC / CPA," "subsequent conditional cell change or addition," "subsequent conditional handover," "selective activation of an SCG," "subsequent SCG change," or "subsequent cell group change or addition." In the context of this application, the term "cell change or addition" may be used interchangeably with "reconfigurationWithSync for an SCG or Master Cell Group (MCG)." In the context of this application, the term "PSCell" refers to an SpCell of an SCG, the term "PCell" refers to an SpCell of an MCG, and "SpCell" refers to the primary cell of an SCG or MCG.

[0033] It was agreed to specify mechanisms and procedures for NR-DC with selective activation of cell groups (at least for SCGs) via Layer 3 (L3) extensions. Specifically, it was agreed to allow subsequent cell group changes after changing a cell group without CPC / CPA reconfiguration and re-setting. It was also agreed that CPA selective activation of cell groups will be supported.

[0034] However, it is unclear how to determine Layer 2 (L2) and security procedures for subsequent CPCs, how to release the configuration for selective activation of cell groups on the network side, and how to support subsequent CPAs after the SCG is released.

[0035] In view of this, an embodiment of the present disclosure provides a solution for selective activation of a cell group. In one aspect, when it is determined that a subsequent conditional cell change is to be performed from a source cell to a target cell, the terminal device performs a set of procedures including at least one of updating a security key associated with the target cell, performing Packet Data Convergence Protocol (PDCP) re-establishment for a Data Radio Bearer (DRB) and a Signaling Radio Bearer (SRB), or performing Radio Link Control (RLC) re-establishment for the DRB and the SRB. In this way, the UE behavior for the selective activation of a cell group can be clarified.

[0036] In another aspect, when a message indicating a conditional cell change from a source cell to a target cell is received from a terminal device, the network device transmits an instruction to another network device that provided the source cell, indicating release of the connection with the terminal device, thereby clarifying the network behavior of releasing the connection with the terminal device for selective activation of a cell group.

[0037] In yet another aspect, when it is determined that the configuration for the subsequent conditional cell change or addition is to be released, the network device transmits an indication indicating the release of the configuration for the subsequent conditional cell change or addition to another network device that provides a candidate cell for the subsequent conditional cell change or addition. In this way, the network behavior of releasing the configuration for the selective activation of the cell group can be made clear.

[0038] It should be understood that the present solution may be applied to either an SCG change or an MCG change. For convenience, the following CPC will be taken as an example to describe the embodiments of the present disclosure.

[0039] The principles and embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings. Communication Network Example

[0040] 1A is a schematic diagram of an exemplary communication network 100A in which embodiments of the present disclosure can be implemented. As shown in FIG. 1A, communication network 100A may include a network device 110 and a terminal device 120. Network device 110 provides a cell 111, and terminal device 120 is located within cell 111 and is served by network device 110.

[0041] The communication network 100A may further include one or more other network devices, for example, network devices 130, 140, and 150. Network device 130 provides cells 131, 132, and 133. Network device 140 provides cells 141, 142, and 143, and network device 150 provides cells 151, 152, and 153. Note that the number of cells is not limited to three, and more or fewer cells may be configured for the terminal device 110.

[0042] Assume that the terminal device 120 is capable of establishing dual connectivity (i.e., simultaneous connection) with two network devices. For example, the network device 110 may function as an MN (hereinafter, for convenience, also referred to as MN 110), and the network device 130 may function as an SN (hereinafter, for convenience, also referred to as SN 130). Although only cell 111 is shown, the MN 110 may provide multiple cells, and these cells may form an MCG for the terminal device 120. Assume that the cell 111 is a primary cell (i.e., a PCell) in the MCG. Furthermore, cells 131, 132, and 133 provided by the network device 130 may form an SCG for the terminal device 120. Assume that the cell 131 is a primary cell (i.e., a PSCell) in the SCG.

[0043] The SN 130 may communicate with the terminal device 120 via a channel such as a wireless communication channel. Similarly, the MN 110 may communicate with the terminal device 120 via a channel such as a wireless communication channel. The SN 130 may communicate with the MN 110 via a control plane interface such as Xn-C. The MN 110 may communicate with a core network 160 such as the AMF 162 via a control plane interface such as NG-C. The SN 130 may further communicate with the MN 110 via a user plane interface such as Xn-U and with the core network 160 such as the UPF 161 via a user plane interface such as NG-U.

[0044] It should be understood that the number of devices or cells in Figure 1A is given for illustrative purposes and does not imply any limitations on the present disclosure. Communications network 100A may involve any suitable number of network devices and / or terminal devices and / or cells suitable for implementing embodiments of the present disclosure.

[0045] Communications in communication network 100A may conform to any suitable standard, including, but not limited to, Global System for Mobile Communication (GSM), Long Term Evolution (LTE), LTE-Evolution, LTE-Advanced (LTE-A), Wideband Code Division Multiple Access (WCDMA), Code Division Multiple Access (CDMA), GSM EDGE Radio Access Network (GERAN), Machine Type Communication (MTC), etc. Embodiments of the present disclosure may be performed in accordance with any generation of communication protocols now known or developed in the future. Examples of communication protocols include, but are not limited to, first generation (1G), second generation (2G), 2.5G, 2.75G, third generation (3G), fourth generation (4G), 4.5G, fifth generation (5G) communication protocols, 5.5G, 5G-Advanced networks, or sixth generation (6G) networks.

[0046] Communication in the direction from terminal device 120 to network device 110, 130, 140, or 150 is referred to as UL communication, and communication in the reverse direction from network device 110, 130, 140, or 150 to terminal device 120 is referred to as DL communication. Terminal device 120 may travel between cells of network device 110, 130, 140, or 150, and possibly other network devices. In UL communication, terminal device 120 may transmit UL data and control information to network device 110, 130, 140, or 150 over an UL channel. In DL communication, network device 110, 130, 140, or 150 may transmit DL data and control information to terminal device 120 over a DL channel.

[0047] Communications in the communication network 100A may be performed according to UP and CP protocol stacks. Generally speaking, for a communication device (e.g., a terminal device or a network device), there may be multiple entities at multiple network protocol layers in the protocol stack, and these entities may be configured to perform corresponding processes on data or signaling transmitted from and received by the communication device. FIG. 1B is a schematic diagram 100B illustrating network protocol layer entities that may be established for a UP protocol stack in an apparatus according to some embodiments of the present disclosure. For convenience, the following description will be given taking communication between a terminal device 120 and a network device 110 as an example. It should be understood that the following description is also applicable to communication between a terminal device 120 and a network device 130, 140, or 150.

[0048] 1B , in the UP, each of the terminal device 120 and the network device 110 may include an L1 layer entity, i.e., a physical (PHY) layer entity (also referred to as a PHY entity), and one or more entities of higher layers (L2 and Layer 3 (L3) layers, or higher layers), including a media access control (MAC) layer entity (also referred to as a MAC entity), a radio link control (RLC) layer entity (also referred to as an RLC entity), a packet data convergence protocol (PDCP) layer entity (also referred to as a PDCP entity), and a service data application protocol (SDAP) layer entity (also referred to as an SDAP entity, which will be established in 5G and subsequent generation networks). In some cases, the PHY, MAC, RLC, PDCP, and SDAP entities have a stack structure.

[0049] FIG. 1C is a schematic diagram 100C illustrating network protocol layer entities that may be established for a CP protocol stack in an apparatus according to some embodiments of the present disclosure. As shown in FIG. 1C , in a CP, each of the terminal device 120 and the network device 110 may include one or more entities of higher layers (L2 and L3 layers), including an L1 layer entity, i.e., a PHY layer entity (also referred to as a PHY entity), a MAC layer entity (also referred to as a MAC entity), an RLC layer entity (also referred to as an RLC entity), a PDCP layer entity (also referred to as a PDCP entity), and a Radio Resource Control (RRC) layer entity (also referred to as an RRC entity). The RRC layer may also be referred to as an Access Stratum (AS) layer, and therefore, the RRC entity may also be referred to as an AS entity. As shown in FIG. 1C , the terminal device 120 may also include a Non-Access Stratum (NAS) layer entity (also referred to as a NAS entity). The NAS layer on the network side is located not in a network device but in a core network (CN, not shown). In some cases, these entities are in a stack structure.

[0050] Generally, communication channels are divided into logical channels, transmission channels, and physical channels. Physical channels are channels through which the PHY layer actually transmits information. For example, physical channels may include a physical uplink control channel (PUCCH), a physical uplink shared channel (PUSCH), a physical random-access channel (PRACH), a physical downlink control channel (PDCCH), a physical downlink shared channel (PDSCH), and a physical broadcast channel (PBCH).

[0051] The transmission channel is a channel between the PHY layer and the MAC layer, and may include, for example, a broadcast channel (BCH), a downlink shared channel (DL-SCH), a paging channel (PCH), an uplink shared channel (UL-SCH), and a random access channel (RACH).

[0052] Logical channels are channels between the MAC layer and the RLC layer. For example, logical channels may include a dedicated control channel (DCCH), a common control channel (CCCH), a paging control channel (PCCH), a broadcast control channel (BCCH), and a dedicated traffic channel (DTCH).

[0053] Generally, the channel between the RRC layer and the PDCP layer is referred to as a radio bearer. The terminal device 120 may be configured with at least one DRB for carrying data plane data and at least one SRB for carrying control plane data.

[0054] In some embodiments, the network device 110 may configure the terminal device 120 with a conditional reconfiguration for the set of candidate cells, which may indicate that subsequent CPC is enabled.

[0055] Assume that cells 131-133, 141-143, and 151-153 are configured as candidate cells for terminal device 120. In some scenarios, terminal device 120 may initially communicate only with network device 110. As terminal device 120 moves, if the conditions for a candidate cell (e.g., cell 131) are met, terminal device 120 may be allowed to establish dual connectivity with network device 110 and network device 130. This process of SN addition may be referred to as CPA.

[0056] In some scenarios, terminal device 120 may establish dual connectivity with network devices 110 and 130. Network device 110 functions as an MN, and network device 130 functions as an SN. As terminal device 120 moves, if a condition for another candidate cell (e.g., cell 142) is met, the SN serving terminal device 120 may change from network device 130 (also referred to as source SN or current SN 130) to network device 140 (also referred to as target SN 140). This PSCell change process may be referred to as CPC. In some scenarios, after conditional reconfiguration is configured for the terminal device and subsequent CPC is enabled, but before at least one execution condition is met for any candidate PSCell, terminal device 120 may receive an RRC reconfiguration message including reconfigurationWithSync from network device 110 and perform a PSCell change or addition accordingly. This procedure is referred to as conventional PSCell change or addition. As an example, after a conventional PSCell change or addition procedure, the SN serving the terminal device 120 is the network device 140.

[0057] After the above CPA, CPC, or conventional PSCell change / addition procedure, if the conditions for yet another candidate cell (e.g., cell 152) are met as terminal device 120 moves further, the SN serving terminal device 120 may be changed from network device 140 to network device 150 (also referred to as target SN 150). This SN change process may be referred to as subsequent CPC. As terminal device 120 moves further, several more rounds of subsequent CPC may be performed.

[0058] As terminal device 120 moves further, it may move out of the coverage of network device 130, 140, or 150. In this case, all SNs may be released. When terminal device 120 again enters the coverage of network device 130, 140, or 150, SN addition may be performed. This process of SN addition may be referred to as subsequent CPA. As terminal device 120 moves further, several more rounds of subsequent CPA may be performed.

[0059] The embodiments of the present disclosure provide a communication solution for selective activation of cell groups, for example, subsequent CPC or subsequent CPA. Example implementation of UE behavior for selective activation of cell groups

[0060] In the past, whether a UE performs PDCD re-establishment, PDCP recovery, PDCP SDU discard, RLC re-establishment, and security key update is based on explicit instructions in the RRCReconfiguration message. However, in the case of a subsequent CPC, the network cannot predict the UE's movement trajectory and therefore cannot properly configure these behaviors in the RRCReconfiguration message.

[0061] To address these and other potential problems, embodiments of the present disclosure provide a solution for selective activation of cell groups, which is conveniently described below in conjunction with FIG.

[0062] FIG. 2 is a schematic diagram illustrating an exemplary communication process 200 according to an embodiment of the present disclosure. For illustrative purposes, process 200 will be described with reference to FIG. 1A. Process 200 may involve terminal device 120 and network devices 110, 130, and 140 as shown in FIG. 1A. In this example, network device 110 is a MN (hereinafter referred to as MN 110 for convenience) serving terminal device 120, network device 140 is a potential target SN (hereinafter referred to as SN 140 for convenience) serving terminal device 120, and cell 143 is a target PSCell. Assume that network device 130 is a source SN (hereinafter referred to as SN 130 for convenience) serving terminal device 120, and terminal device 120 is served by cell 131 (i.e., the source PSCell).

[0063] 2, terminal device 120 may receive 210 a configuration (e.g., conditional reconfiguration) for selective activation of a cell group. In some embodiments, for example, terminal device 120 may receive 211 a conditional reconfiguration from MN 110.

[0064] In some embodiments, the configuration for selective activation of a cell group may indicate a set of configurations for a set of candidate cells (e.g., cells 132, 133, 141, 142, 143, 151, 152, and 153) and a cell change condition associated with each candidate cell in the set of candidate cells. In some embodiments, the configuration for selective activation of a cell group may further include a cell addition condition associated with each candidate cell in the set of candidate cells. It should be understood that the configuration may include any suitable information, and the disclosure is not limited in this respect.

[0065] The terminal device 120 may determine (220) that a subsequent conditional cell change is to be performed from the source PSCell (cell 131) to a target PSCell (e.g., cell 143). For example, the terminal device 120 may perform measurements on a set of candidate cells and may determine that cell 143 satisfies the cell change condition. The terminal device 120 may then decide to perform an SN change to cell 143 by applying a configuration associated with cell 143.

[0066] The terminal device 120 may perform a set of procedures (also referred to herein as a first set of procedures for convenience) for L2 and security procedures during the subsequent conditional PSCell change (230).

[0067] In some embodiments, the first set of procedures may include updating a security key (also referred to as a secondary key) associated with the target PSCell. In some embodiments, the set of procedures may include performing PDCP re-establishment for DRBs and SRBs, e.g., for all DRBs and all SRBs. In some embodiments, the set of procedures may include performing RLC re-establishment for DRBs and SRBs, e.g., for all DRBs and all SRBs. That is, either the PDCP re-establishment procedure or the RLC re-establishment procedure may be triggered directly by the RRC layer of the terminal device 120 without any indication in the RRCReconfiguration message. It should be understood that the first set of procedures may include any appropriate combination of the above procedures.

[0068] Referring to FIG. 2, in some embodiments, if a subsequent conditional cell change is to be performed, terminal device 120 may directly execute the first set of procedures (231).

[0069] In some alternative embodiments, terminal device 120 may determine 232 whether the source PSCell and target PSCell are provided by different network devices.

[0070] In some embodiments, the terminal device 120 may determine information on the cell identity and network device identity length of the source PSCell and the target PSCell, and may determine whether the source PSCell and the target PSCell are provided by different network devices based on the information on the cell identity and network device identity length of the source PSCell and the target PSCell.

[0071] For example, the terminal device 120 may obtain information on the cell identity (e.g., cellIdentity) and network equipment identity length (e.g., gNB-ID-Length) of the source PSCell from system information (e.g., PLMN-IdentityInforList information element (IE)) of the SN 130 providing the source PSCell (e.g., cell 131), and may determine information on the cell identity and network equipment identity length of the target PSCell via system information from the SN 140 providing the target PSCell (e.g., cell 143).

[0072] The terminal device 120 may determine the identity of the SN 130 providing the source PSCell (for convenience, also referred to as a first identity herein) based on the information of the cell identity and network equipment identity length of the source PSCell, and may determine the identity of the SN 140 providing the target PSCell (for convenience, also referred to as a second identity herein) based on the information of the cell identity and network equipment identity length of the target PSCell. If the first identity is different from the second identity, the terminal device 120 may determine that the source PSCell and the target PSCell are provided by different network devices. If the first identity is the same as the second identity, the terminal device 120 may determine that the source PSCell and the target PSCell are provided by the same network device.

[0073] In some embodiments, the terminal device 120 may determine information associated with a set of candidate cells for a subsequent conditional cell change and determine whether the source PSCell and the target PSCell are provided by different network devices based on the information associated with the set of candidate cells. In some embodiments, the information may be information of a cell group, gNB, or SN associated with the candidate cells. For example, the terminal device 120 may obtain the information associated with the set of candidate cells from a configuration for selective activation of a cell group (e.g., conditional reconfiguration). In other words, the network device 110 may configure the information within or together with a conditional reconfiguration that supports selective activation of a cell group. Of course, any other suitable method is also possible.

[0074] In some embodiments, the information associated with the set of candidate cells may include at least one of the following: an identity of a cell group associated with a candidate cell in the set of candidate cells, an identity of a network device (e.g., a gNB ID) associated with the candidate cell, or an identity of an SN associated with the candidate cell. It should be understood that any other suitable information is also possible. Such information may be useful in determining whether to perform a set of L2 procedures and / or whether to update security keys associated with the target PSCell.

[0075] If the source PSCell and the target PSCell are associated with different cell groups or network devices, the terminal device 120 may determine that the source PSCell and the target PSCell are provided by different network devices. If the source PSCell and the target PSCell are associated with the same cell group or network device, the terminal device 120 may determine that the source PSCell and the target PSCell are provided by the same network device.

[0076] 2, if the source PSCell and the target PSCell are provided by different network devices, the terminal device 120 may perform a first set of procedures (233). If the source PSCell and the target PSCell are provided by the same network device, the terminal device 120 may perform a second set of procedures (234).

[0077] In some embodiments, the second set of procedures may include performing PDCP recovery for DRBs, e.g., for all DRBs. In some embodiments, the second set of procedures may include performing PDCP Service Data Unit (SDU) discard for SRBs, e.g., for all SRBs. In some embodiments, the second set of procedures may include performing RLC re-establishment for DRBs and SRBs, e.g., for all DRBs and all SRBs. In some embodiments, the second set of procedures may include maintaining (i.e., not updating) security keys associated with the target PSCell. It should be understood that the second set of procedures may include any suitable combination of the above procedures.

[0078] In some scenarios, the SCG may be released. Conventionally, when the SCG is released, the UE may release the conditional reconfiguration for the conditional cell change or addition. However, when the conditional reconfiguration supporting the selective activation of the cell group is released, the UE may not be able to perform the subsequent CPA without a new RRC reconfiguration. In view of this, the embodiments of the present disclosure further provide a solution for these scenarios.

[0079] 2, terminal device 120 may determine that an SCG release is to be performed (240). Terminal device 120 may then perform a set of procedures (also referred to herein as a third set of procedures for convenience) (250).

[0080] In some embodiments, the third set of procedures may include maintaining stored information for conditional reconfiguration. In some embodiments, the third set of procedures may include maintaining stored information for conditional reconfiguration supporting selective activation of cell groups. In some embodiments, maintaining stored information for conditional reconfiguration supporting selective activation of cell groups includes at least one of removing entries in a configuration for SN-initiated conditional cell changes (e.g., SCG VarConditionlReconfig), maintaining (i.e., not releasing) stored configuration for MN-initiated conditional reconfiguration supporting selective activation of cell groups (e.g., MCG VarConditionlReconfig), or maintaining (i.e., not releasing) stored configuration for MN-initiated conditional reconfiguration supporting subsequent conditional cell addition (e.g., MCG VarConditionlReconfig).

[0081] In some embodiments, the third set of procedures may include continuing to perform conditional reset evaluations for subsequent conditional cell additions. In some embodiments, the third set of procedures may include suspending conditional reset evaluations for subsequent conditional cell changes. It should be understood that the third set of procedures may include any suitable combination of the above procedures. In this way, subsequent CPAs after SCG release may be supported.

[0082] When a cell change or addition of a PSCell is performed, the terminal device may initiate a random access (RA) procedure to the target PSCell. Conventionally, when the RA procedure is completed, the MAC entity of the terminal device may discard explicitly signaled contention-free random access (CFRA) resources for any 2-step and 4-step RA types. However, this may result in the CFRA resources being unavailable for subsequent CPA and subsequent CPC.

[0083] In view of this, the embodiment of the present disclosure provides a solution for selective activation of a cell group, in which, when the RA procedure for the selective activation procedure of a cell group is completed, the terminal device 120 may maintain (i.e., not discard) the CFRA resources of the corresponding two-step RA and four-step RA.

[0084] So far, the UE behavior for selective activation of cell groups has been clarified. Example implementation of network behavior for selective activation of cell groups

[0085] Conventionally, the MN sends an SN release request message to the SN to release the UE context, i.e., both the UE connection and the conditional reconfiguration (and all other UE contexts) are released. However, in the case of selective activation of a cell group, the SN may only need to release the UE connection and maintain the conditional reconfiguration for the selective activation of the cell group. Therefore, it is unclear how to indicate the release of the UE connection and the release of the conditional reconfiguration separately.

[0086] To address these and other potential problems, embodiments of the present disclosure provide a solution for selective activation of cell groups, which is conveniently described below in conjunction with FIG.

[0087] 3 is a schematic diagram illustrating another exemplary communication process 300 according to an embodiment of the present disclosure. For illustrative purposes, the process 300 will be described with reference to FIG. 1A. The process 300 may involve terminal device 120 and network devices 110 and 130 as shown in FIG. 1A. In this example, network device 110 is an MN (hereinafter referred to as MN 110 for convenience) that serves terminal device 120, network device 130 is a source SN (hereinafter referred to as SN 130 for convenience) that serves terminal device 120, and terminal device 120 is in cell 131 (i.e., a source PSCell).

[0088] 3, the terminal device 120 may transmit 310 a message to the MN 110 indicating that a conditional cell change is to be performed from a source PSCell (e.g., cell 131) to a target PSCell (e.g., cell 143). In some embodiments, the conditional cell change may be a subsequent conditional cell change. For example, if CPC is triggered, the terminal device 120 may transmit an RRCReconfigurationComplete message to the MN 110, the RRCReconfigurationComplete message including an RRCReconfigurationComplete message for the selected candidate cell.

[0089] The MN 110 may transmit (320) an indication to the SN 130 that provides the source PSCell indicating the release of the connection with the terminal device 120. Alternatively, the MN 110 may transmit an indication to the SN 130 indicating the deactivation or suspension of the cell group. Alternatively, the MN 110 may transmit an indication to the SN 130 indicating the withdrawal of the terminal device 120.

[0090] In some embodiments, the MN 110 may send the indication via an Xn message. In some embodiments, the Xn message may be a newly defined message. In some embodiments, the Xn message may be an existing message, such as an SN release request message. In some embodiments, the SN release request message may include an IE indicating release of the connection with the terminal device 120, deactivation or suspension of a cell group, or withdrawal of the terminal device 120. It should be understood that any other suitable method is also possible.

[0091] Continuing with reference to FIG. 3, once the indication is received, the SN 130 may release (330) the connection with the terminal device 120 while maintaining the UE context (i.e., maintaining the conditional reconfiguration that supports selective activation of cell groups for the UE). The SN 130 may send (340) an acknowledgement (ACK) to the MN 110 for the release of the connection with the terminal device 120. Alternatively, the SN 130 may send an ACK for the deactivation or suspension of the cell group. Alternatively, the SN 130 may send an ACK for the withdrawal of the terminal device 120.

[0092] In some embodiments, the ACK may be sent within an Xn message. In some embodiments, the Xn message may be a newly defined message. In some embodiments, the Xn message may be an existing message, such as an SN Release Request Acknowledgement message. It should be understood that any other suitable method is also possible.

[0093] Thus, the release of the UE connection may be indicated separately from the release of the conditional reconfiguration.

[0094] 4 is a schematic diagram illustrating yet another exemplary communication process 400 according to an embodiment of the present disclosure. For illustrative purposes, the process 400 will be described with reference to FIG. 1A. The process 400 may involve the network device 110 and the network devices 130, 140, or 150 as shown in FIG. 1A. In this example, the network device 110 is an MN (hereinafter referred to as MN 110 for convenience) that serves the terminal device 120, and the network devices 130, 140, and 150 are SNs that serve candidate cells. For convenience, only the network device 130 is shown as an example.

[0095] 4, the MN 110 may determine 410 that the conditional configuration for subsequent conditional cell additions or modifications (i.e., selective activation of cell groups) is to be released. In some embodiments, an SN (e.g., SN 130, 140, or 150) may decide to release the configuration for subsequent conditional cell additions or modifications and notify the MN 120 of the decision.

[0096] Referring to FIG. 4, the MN 110 may send an indication indicating the release of the configuration for a subsequent conditional cell addition or modification to the SN 130, 140, or 150 that provides a candidate cell for the subsequent conditional cell addition or modification (420).

[0097] In some embodiments, the MN 110 may send the indication via an Xn message. In some embodiments, the Xn message may be a newly defined message. In some embodiments, the Xn message may be an existing message, such as an SN release request message. In some embodiments, the SN release message may include an IE indicating cancellation or release of the configuration for selective activation of a cell group. It should be understood that any other suitable method is also possible.

[0098] Continuing with reference to FIG. 4, the SN 130, 140, or 150 may release the configuration for subsequent conditional cell additions or modifications (430). The SN 130, 140, or 150 may send an ACK for the release of the configuration for subsequent conditional cell additions or modifications to the MN 110 (440). In some embodiments, the ACK may be sent within an Xn message. In some embodiments, the Xn message may be a newly defined message. In some embodiments, the Xn message may be an existing message, such as an SN Release Request Acknowledgement message. It should be understood that any other suitable method is also possible.

[0099] Thus, the release of the conditional reconfiguration may be indicated separately from the release of the UE connection.

[0100] It should be noted that the operations in processes 200, 300 and 400 may be performed separately or in any suitable combination. Example implementation of the method

[0101] Therefore, embodiments of the present disclosure provide communication methods implemented in a terminal device and a network device, which are described below with reference to Figures 5 to 7.

[0102] 5 illustrates an exemplary communication method 500 implemented in a terminal device, according to some embodiments of the present disclosure. For example, method 500 may be performed in terminal device 120 as shown in FIG. 1A. For purposes of explanation, method 500 will be described below with reference to FIG. 1A. It should be understood that method 500 may include additional blocks not shown and / or omit some blocks that are shown, and that the scope of the present disclosure is not limited in this respect.

[0103] In block 510, terminal device 120 determines that a subsequent conditional cell change is to be performed from the source cell to the target cell.

[0104] In block 520, the terminal device 120 performs a first set of procedures during the subsequent conditional cell change, the first set of procedures including at least one of updating security keys associated with the target cell, performing PDCP re-establishment for the DRBs and SRBs, or performing RLC re-establishment for the DRBs and SRBs.

[0105] In some embodiments, the terminal device 120 may determine information on the cell identity and network equipment identity length of the source cell and the target cell, and determine whether the source cell and the target cell are provided by different network equipment based on the information on the cell identity and network equipment identity length of the source cell and the target cell.

[0106] In some embodiments, terminal device 120 may determine a first identity of a network device providing the source cell based on information about the cell identity and network device identity length of the source cell, and may determine a second identity of a network device providing the target cell based on information about the cell identity and network device identity length of the target cell. If the first identity is the same as the second identity, terminal device 120 may determine that the source cell and the target cell are provided by the same network device. If the first identity is different from the second identity, terminal device 120 may determine that the source cell and the target cell are provided by different network devices.

[0107] In some embodiments, terminal device 120 may determine information associated with a set of candidate cells for a subsequent conditional cell change and determine whether the source cell and the target cell are provided by different network devices based on the information associated with the set of candidate cells. In some embodiments, the information associated with the set of candidate cells may include at least one of an identity of a cell group associated with a candidate cell in the set of candidate cells, an identity of a network device associated with the candidate cell, or an identity of a secondary node associated with the candidate cell.

[0108] In some embodiments, if the source cell and the target cell are provided by different network devices, the terminal device 120 may perform a first set of procedures. In some embodiments, the terminal device 120 may determine that the source cell and the target cell are provided by the same network device based on information about the cell identities and network device identity lengths of the source cell and the target cell. In these embodiments, the terminal device 120 may perform a second set of procedures including at least one of performing PDCP recovery for the DRB, performing PDCP service data unit (SDU) discard for the SRB, performing RLC re-establishment for the DRB and the SRB, or maintaining security keys associated with the target cell.

[0109] In some embodiments, terminal device 120 may determine that an SCG release is to be performed. In these embodiments, terminal device 120 may perform a third set of procedures including at least one of maintaining stored information of the conditional reconfiguration, continuing to perform evaluation for a subsequent conditional cell addition, or pausing evaluation for a subsequent conditional cell change.

[0110] In some embodiments, terminal device 120 may maintain stored information for conditional reconfiguration by at least one of removing entries in the configuration for subsequent conditional cell changes initiated by the SN, maintaining stored configuration for subsequent conditional cell changes initiated by the MN, or maintaining stored configuration for subsequent conditional cell additions initiated by the MN.

[0111] In some embodiments, terminal device 120 may perform an RA procedure for a subsequent conditional cell change or addition. Once the RA procedure is completed, terminal device 120 may maintain the CFRA resources.

[0112] Method 500 may clarify UE behavior to better support selective activation of cell groups.

[0113] 6 illustrates an exemplary communication method 600 implemented in a network device according to some embodiments of the present disclosure. For example, method 600 may be performed in network device 110 as shown in FIG. 1A. For purposes of explanation, method 600 will be described below with reference to FIG. 1A. It should be understood that method 600 may include additional blocks not shown and / or omit some blocks that are shown, and that the scope of the present disclosure is not limited in this respect.

[0114] In block 610, a first network device (e.g., network device 110) receives a message from a terminal device (e.g., terminal device 120) indicating that a conditional cell change is to be performed from a source cell (e.g., cell 131) to a target cell (e.g., cell 143).

[0115] In block 620, the network device 110 transmits an indication to a second network device (e.g., network device 130) that provides the source cell indicating the release of the connection with the terminal device 120. In this manner, the second network device may release the connection with the terminal device 120 and maintain the configuration for selective activation of the cell group. It should be understood that the indication may be transmitted in any suitable manner.

[0116] In some embodiments, network device 110 may receive an ACK from network device 130 regarding the release of the connection with terminal device 120. It should be understood that the ACK may be transmitted in any suitable manner.

[0117] Method 600 may clarify network behavior to better support subsequent CPCs.

[0118] 7 illustrates another exemplary communication method 700 implemented in a network device, according to some embodiments of the present disclosure. For example, method 700 may be performed in network device 110 as shown in FIG. 1A. For purposes of explanation, method 700 will be described below with reference to FIG. 1A. It should be understood that method 700 may include additional blocks not shown and / or omit some blocks that are shown, and that the scope of the present disclosure is not limited in this respect.

[0119] In block 710, a first network device (eg, network device 110) determines that the configuration for subsequent conditional cell additions or modifications is released.

[0120] In block 720, network device 110 transmits an indication indicating the release of the configuration for the subsequent conditional cell addition or modification to a second network device (e.g., network device 130, 140, or 150) that provides a candidate cell for the subsequent conditional cell addition or modification. It should be understood that the indication may be transmitted in any suitable manner.

[0121] In some embodiments, network device 110 may receive an ACK for the de-configuration of the subsequent conditional cell addition or modification from a second network device (e.g., network device 130, 140, or 150). It should be understood that the ACK may be transmitted in any suitable manner.

[0122] The method 700 may clarify network behavior to better support subsequent CPAs.

[0123] It should be noted that the operation of methods 500, 600 and 700 is similar to the operation described in connection with FIGS. 2-4, and therefore other details will not be repeated here for the sake of brevity. Device and equipment implementation examples

[0124] 8 is a schematic block diagram of an apparatus 800 suitable for implementing embodiments of the present disclosure. Apparatus 800 may be considered as another exemplary implementation of terminal device 120 or network device 110, 130, or 140 as shown in FIG. 1A. Thus, apparatus 800 may be implemented in, or as at least a part of, terminal device 120 or network device 110, 130, or 140.

[0125] As shown, the apparatus 800 comprises a processor 810, a memory 820 coupled to the processor 810, a suitable transmitter (TX) and receiver (RX) 840 coupled to the processor 810, and a communication interface coupled to the TX / RX 840. The memory 810 stores at least a portion of a program 830. The TX / RX 840 is used for bidirectional communication. The TX / RX 840 has at least one antenna to facilitate communication, although the access nodes referred to herein may in practice have multiple antennas. The communication interface may represent any interface required for communication with other network elements, such as an X2 / Xn interface for bidirectional communication between eNBs / gNBs, an S1 / NG interface for communication between a Mobility Management Entity (MME) / Access and Mobility Management Function (AMF) / SGW / UPF and an eNB / gNB, an Un interface for communication between an eNB / gNB and a Relay Node (RN), or a Uu interface for communication between an eNB / gNB and a terminal device.

[0126] The program 830 is assumed to include program instructions that, when executed by the associated processor 810, enable the device 800 to operate according to embodiments of the present disclosure, as described herein with reference to Figures 2-7. The embodiments herein may be implemented by computer software executable by the processor 810 of the device 800, by hardware, or by a combination of software and hardware. The processor 810 may be configured to implement various embodiments of the present disclosure. Furthermore, the combination of the processor 810 and the memory 820 may form a processing means 850 suitable for implementing various embodiments of the present disclosure.

[0127] Memory 820 may be of any type suitable for a local technology network and may be implemented using any suitable data storage technology, including, by way of non-limiting example, non-transitory computer-readable storage media, semiconductor-based memory devices, magnetic memory devices and systems, optical memory devices and systems, fixed memory, and removable memory. While only one memory 820 is shown in device 800, there may be several physically distinct memory modules within device 800. Processor 810 may be of any type suitable for a local technology network and may include, by way of non-limiting example, one or more of 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. Device 800 may have multiple processors, for example, application-specific integrated circuit chips time-slaved to a clock that synchronizes the main processor.

[0128] In some embodiments, a terminal device comprises circuitry configured to determine that a subsequent conditional cell change is to be performed from a source cell to a target cell and to perform a first set of procedures including at least one of updating security keys associated with the target cell, performing PDCP re-establishment for DRBs and SRBs, or performing RLC re-establishment for the DRBs and the SRBs.

[0129] In some embodiments, the first network device comprises circuitry configured to receive a message from a terminal device indicating that a conditional cell change is to be performed from a source cell to a target cell, and to send an indication to a second network device providing the source cell indicating release of a connection with the terminal device.

[0130] In some embodiments, the first network device comprises circuitry configured to determine that a configuration for a subsequent conditional cell addition or modification is to be released and to send an indication indicating the release of the configuration for the subsequent conditional cell addition or modification to a second network device that provides a candidate cell for the subsequent conditional cell addition or modification.

[0131] As used herein, the term "circuitry" may refer to a hardware circuit and / or a combination of a hardware circuit and software. For example, a circuit may be a combination of analog and / or digital hardware circuitry and software / firmware. As yet another example, a circuit may be any portion of a hardware processor with software, including a digital signal processor, software, and one or more memories, that cooperate to cause a device, such as a terminal device or a network device, to perform various functions. In yet another example, a circuit may be a hardware circuit and / or a processor, such as a microprocessor or portion thereof, that requires software / firmware for operation, although software may not be present if not necessary for operation. As used herein, the term "circuitry" also includes an implementation of a hardware circuit or one or more processors only, or a hardware circuit or portion of one or more processors and its / their associated software and / or firmware.

[0132] Overall, various embodiments of the present disclosure may be implemented in hardware or special purpose circuits, software, logic, or any combination thereof. Some aspects may be implemented in hardware, while other aspects may be implemented in firmware or software executable by a controller, microprocessor, or other computing device. While various aspects of embodiments of the present disclosure have been illustrated and described using block diagrams, flowcharts, or other pictorial representations, it should be understood that the blocks, devices, systems, techniques, or methods described herein may be implemented, by way of non-limiting example, in hardware, software, firmware, special purpose circuits or logic, general purpose hardware or controller or other computing device, or any combination thereof.

[0133] The present disclosure also provides at least one computer program product tangibly stored on a non-transitory computer-readable storage medium. The computer program product includes computer-executable instructions, such as instructions included in program modules, that execute within a device on a target real or virtual processor to perform the processes or methods described above with reference to Figures 2-7. Generally, program modules include routines, programs, libraries, objects, classes, components, data structures, etc. that perform particular tasks or implement particular abstract data types. In various embodiments, the functionality of the program modules may be combined or split between program modules as desired. The machine-executable instructions of the program modules may be executed within local or distributed devices. In a distributed device, program modules may be located in both local and remote storage media.

[0134] Program code for carrying out the methods of the present disclosure may be written in any combination of one or more programming languages. These program codes may be provided to a processor or controller of a general-purpose computer, a special-purpose computer, or other programmable data processing device, and when executed by the processor or controller, cause the program code to implement the functions / acts specified in the flowcharts and / or block diagrams. The program code may run entirely on the machine, partially on the machine, as a separate software package, partially on the machine and partially on a remote machine, or entirely on a remote machine or server.

[0135] The above-described program code may be embodied on a machine-readable medium, which may be any tangible medium that can contain or store a program used by or associated with an instruction execution system, apparatus, or device. The machine-readable medium may be a machine-readable signal medium or a machine-readable storage medium. The machine-readable medium may include, but is not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination of the aforementioned media. More specific examples of a machine-readable storage medium may include an electrical connection having 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 disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the above.

[0136] It should be noted that, although operations have been described in a particular order, it should not be understood that performing such operations in the particular order shown, or in any sequential order, or performing all of the operations described, is required to achieve desirable results. In some cases, multitasking and parallel processing may be advantageous. Similarly, while several specific implementation details are included in the above discussion, these should not be construed as limitations on the scope of the disclosure, but rather as descriptions of features that may be specific to particular embodiments. Some features that are described in the context of individual embodiments may also be implemented in combination in a single embodiment. Conversely, various features that are described in the context of a single embodiment may also be implemented in multiple embodiments separately or in any suitable subcombination.

[0137] Although the present disclosure has been described in language specific to structural features and / or methodological acts, it should be understood that the present disclosure, as defined in the appended claims, is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as example forms of implementing the claims.

Claims

1. A method of communication comprising: determining, in the terminal device, that a subsequent conditional cell change is to be performed from the source cell to the target cell; updating a security key associated with the target cell; performing Packet Data Convergence Protocol (PDCP) re-establishment for Data Radio Bearers (DRBs) and Signaling Radio Bearers (SRBs); or performing a Radio Link Control (RLC) re-establishment for the DRB and the SRB; A method comprising:

2. Executing the first set of procedures includes: determining cell identity and network equipment identity length information of the source cell and the target cell; determining that the source cell and the target cell are provided by different network devices based on the information of the cell identities and the network device identity lengths of the source cell and the target cell; executing the first set of procedures. The method of claim 1.

3. determining, based on the information of the cell identities and the network equipment identity lengths of the source cell and the target cell, that the source cell and the target cell are provided by the same network equipment; performing PDCP recovery for the DRB; performing PDCP Service Data Unit (SDU) discarding for the SRB; performing the RLC re-establishment for the DRB and the SRB; or maintaining the security key associated with the target cell; The method of claim 2 further comprising:

4. determining a first identity of a network device serving the source cell based on the information of the cell identity of the source cell and the network device identity length; determining a second identity of a network device serving the target cell based on the information of the cell identity of the target cell and the network device identity length; determining, according to a determination that the first identity is the same as the second identity, that the source cell and the target cell are provided by the same network device; determining, in accordance with determining that the first identity is different from the second identity, that the source cell and the target cell are provided by different network devices; The method of claim 3 further comprising:

5. Executing the first set of procedures includes: determining information associated with a set of candidate cells for the subsequent conditional cell change; determining, based on the information associated with the set of candidate cells, that the source cell and the target cell are provided by different network devices; executing the first set of procedures. The method of claim 1.

6. The information associated with the set of candidate cells includes: the identity of a cell group associated with a candidate cell from the set of candidate cells; the identity of a network device associated with the candidate cell; or the identity of a secondary node associated with the candidate cell. The method of claim 5.

7. determining, based on the information associated with the set of candidate cells, that the source cell and the target cell are provided by the same network device; performing PDCP recovery for the DRB; performing PDCP Service Data Unit (SDU) discarding for the SRB; performing the RLC re-establishment for the DRB and the SRB; or maintaining the security key associated with the target cell; The method of claim 5 further comprising:

8. determining that a Secondary Cell Group (SCG) release is to be performed; maintaining stored conditional reset information; Continue to perform evaluations for subsequent conditional cell additions, or and suspending evaluation of the subsequent conditional cell change. The method of claim 1 further comprising:

9. Maintaining the stored information of the conditional resetting includes: removing entries in the configuration for subsequent conditional cell changes initiated by the secondary node; Maintaining the stored configuration for subsequent conditional cell changes initiated by the master node; or and maintaining the stored configuration for subsequent conditional cell additions initiated by the master node. The method of claim 8.

10. performing a random access procedure for a subsequent conditional cell change or addition; maintaining a contention-free random access resource upon completion of the random access procedure; The method of claim 1 further comprising:

11. A method of communication comprising: receiving, at a first network device, a message from a terminal device indicating that a conditional cell change is to be performed from a source cell to a target cell; sending an indication to a second network device providing the source cell indicating the release of the connection with the terminal device; A method comprising:

12. receiving an acknowledgement from the second network device regarding the release of the connection with the terminal device; The method of claim 11 further comprising:

13. A method of communication comprising: determining that a setting for subsequent conditional cell addition or modification is released in the first network device; sending an indication indicating the release of the configuration for the subsequent conditional cell addition or modification to a second network device that provides a candidate cell for the subsequent conditional cell addition or modification; A method comprising:

14. receiving an acknowledgement from the second network device regarding the release of the configuration for the subsequent conditional cell addition or modification; The method of claim 13 further comprising:

15. A communication device, comprising: A processor configured to cause the device to perform the method of any one of claims 1 to 10, any one of claims 11 to 12, or any one of claims 13 to 14. Device.

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