Delayed access to primary cell of secondary cell group

Abstract

A method is disclosed that includes receiving one or more configurations for conditional handover, where the configurations include at least a primary cell group configuration of a target primary cell of a primary cell group, and a secondary cell group configuration of a target primary cell of a secondary cell group, and wherein the configuration is associated with at least one execution condition of the conditional handover and at least one access condition of a target primary cell of the secondary cell group; when it is detected that at least one execution condition is met, accessing a target primary cell of the primary cell group; and delaying access to a target primary cell of the secondary cell group based on determining that at least one access condition is not satisfied when at least one execution condition of the conditional handover is detected to be satisfied.

Description

Technical Field

[0001] The following example embodiments relate to wireless communications. Background Art

[0002] During a handover process, cellular transmissions can be transferred from one cell to another. However, if the handover is not timed appropriately, the quality of the cellular transmissions may be negatively impacted. Therefore, it is desirable to provide an improved handover process. Summary of the Invention

[0003] The scope of protection sought by various exemplary embodiments is defined by the independent claims. Exemplary embodiments and features described in this specification that do not fall within the scope of the independent claims, if any, should be interpreted as examples that aid in understanding the various embodiments.

[0004] According to one aspect, a device is provided, which includes at least one processor and at least one memory storing instructions, which instructions, when executed by the at least one processor, cause the device to at least: receive one or more configurations of conditional switching, wherein the configuration in the one or more configurations includes at least: a primary cell group configuration of a target primary cell of a primary cell group, and a secondary cell group configuration of a target primary cell of a secondary cell group, and wherein the configuration is associated with at least one execution condition of the conditional switching and at least one access condition of the target primary cell of the secondary cell group; access the target primary cell of the primary cell group when it is detected that at least one execution condition is met; and delay access to the target primary cell of the secondary cell group based on determining that at least one access condition is not met when it is detected that at least one execution condition of the conditional switching is met.

[0005] According to another aspect, a device is provided, comprising: a component for receiving one or more configurations of conditional switching, wherein the configuration in the one or more configurations includes at least: a primary cell group configuration of a target primary cell of a primary cell group, and a secondary cell group configuration of a target primary cell of a secondary cell group, and wherein the configuration is associated with at least one execution condition of the conditional switching and at least one access condition of the target primary cell of the secondary cell group; a component for accessing the target primary cell of the primary cell group when it is detected that at least one execution condition is met; and a component for delaying access to the target primary cell of the secondary cell group based on determining that at least one access condition is not met when it is detected that at least one execution condition of the conditional switching is met.

[0006] According to another aspect, a method is provided, which includes: receiving one or more configurations of conditional switching, wherein the configuration in the one or more configurations includes at least: a primary cell group configuration of a target primary cell of a primary cell group, and a secondary cell group configuration of a target primary cell of a secondary cell group, and wherein the configuration is associated with at least one execution condition of the conditional switching and at least one access condition of the target primary cell of the secondary cell group; accessing the target primary cell of the primary cell group when it is detected that at least one execution condition is met; and delaying access to the target primary cell of the secondary cell group based on determining that at least one access condition is not met when it is detected that at least one execution condition of the conditional switching is met.

[0007] According to another aspect, a computer program comprising instructions is provided, which, when executed by an apparatus, causes the apparatus to at least perform: receiving one or more configurations of conditional switching, wherein the configuration in the one or more configurations includes at least: a primary cell group configuration of a target primary cell of a primary cell group, and a secondary cell group configuration of a target primary cell of a secondary cell group, and wherein the configuration is associated with at least one execution condition of the conditional switching and at least one access condition of the target primary cell of the secondary cell group; accessing the target primary cell of the primary cell group when detecting that at least one execution condition is met; and delaying access to the target primary cell of the secondary cell group based on determining that at least one access condition is not met when detecting that at least one execution condition of the conditional switching is met.

[0008] According to another aspect, a computer-readable medium comprising program instructions is provided, which, when executed by an apparatus, causes the apparatus to at least perform: receiving one or more configurations of conditional switching, wherein the configuration in the one or more configurations includes at least: a primary cell group configuration of a target primary cell of a primary cell group, and a secondary cell group configuration of a target primary cell of a secondary cell group, and wherein the configuration is associated with at least one execution condition of the conditional switching and at least one access condition of the target primary cell of the secondary cell group; accessing the target primary cell of the primary cell group when detecting that at least one execution condition is met; and delaying access to the target primary cell of the secondary cell group based on determining that at least one access condition is not met when detecting that at least one execution condition of the conditional switching is met.

[0009] According to another aspect, a non-transitory computer-readable medium comprising program instructions is provided, which, when executed by an apparatus, causes the apparatus to at least perform: receiving one or more configurations of conditional switching, wherein the configuration in the one or more configurations comprises at least: a primary cell group configuration of a target primary cell of a primary cell group, and a secondary cell group configuration of a target primary cell of a secondary cell group, and wherein the configuration is associated with at least one execution condition of the conditional switching and at least one access condition of the target primary cell of the secondary cell group; accessing the target primary cell of the primary cell group when detecting that at least one execution condition is met; and delaying access to the target primary cell of the secondary cell group based on determining that at least one access condition is not met when detecting that at least one execution condition of the conditional switching is met.

[0010] According to another aspect, a device is provided, which includes at least one processor and at least one memory storing instructions, which instructions, when executed by the at least one processor, cause the device to at least: determine one or more configurations of conditional switching of a user equipment, wherein the configuration in the one or more configurations includes at least: a primary cell group configuration of a target primary cell of a primary cell group, and a secondary cell group configuration of a target primary cell of a secondary cell group, and wherein the configuration is associated with at least one execution condition of the conditional switching and at least one access condition of the target primary cell of the secondary cell group; send one or more configurations, wherein the one or more configurations indicate: delaying access to the target primary cell of the secondary cell group based on determining that at least one access condition is not met when detecting that at least one execution condition of the conditional switching is met.

[0011] According to another aspect, an apparatus is provided, comprising: a component for determining one or more configurations for conditional switching of a user equipment, wherein the configuration in the one or more configurations includes at least: a primary cell group configuration of a target primary cell of a primary cell group, and a secondary cell group configuration of a target primary cell of a secondary cell group, and wherein the configuration is associated with at least one execution condition for conditional switching and at least one access condition of the target primary cell of the secondary cell group; and a component for sending one or more configurations, wherein the one or more configurations indicate: delaying access to the target primary cell of the secondary cell group based on determining that at least one access condition is not met when detecting that at least one execution condition for conditional switching is met.

[0012] According to another aspect, a method is provided, which includes: determining one or more configurations for conditional switching of a user equipment, wherein the configuration in the one or more configurations includes at least: a primary cell group configuration of a target primary cell of a primary cell group, and a secondary cell group configuration of a target primary cell of a secondary cell group, and wherein the configuration is associated with at least one execution condition for conditional switching and at least one access condition of the target primary cell of the secondary cell group; sending one or more configurations, wherein the one or more configurations indicate: delaying access to the target primary cell of the secondary cell group based on determining that at least one access condition is not met when detecting that at least one execution condition for conditional switching is met.

[0013] According to another aspect, a computer program comprising instructions is provided, which, when executed by an apparatus, causes the apparatus to at least perform: determining one or more configurations for conditional switching of a user equipment, wherein the configuration in the one or more configurations comprises at least: a primary cell group configuration of a target primary cell of a primary cell group, and a secondary cell group configuration of a target primary cell of a secondary cell group, and wherein the configuration is associated with at least one execution condition for conditional switching and at least one access condition for the target primary cell of the secondary cell group; and sending one or more configurations, wherein the one or more configurations indicate: delaying access to the target primary cell of the secondary cell group based on determining that at least one access condition is not met when detecting that at least one execution condition for conditional switching is met.

[0014] According to another aspect, a computer-readable medium comprising program instructions is provided, which, when executed by an apparatus, causes the apparatus to at least perform: determining one or more configurations for conditional switching of a user equipment, wherein the configuration in the one or more configurations comprises at least: a primary cell group configuration of a target primary cell of a primary cell group, and a secondary cell group configuration of a target primary cell of a secondary cell group, and wherein the configuration is associated with at least one execution condition for conditional switching and at least one access condition for the target primary cell of the secondary cell group; and sending one or more configurations, wherein the one or more configurations indicate: delaying access to the target primary cell of the secondary cell group based on determining that at least one access condition is not met when detecting that at least one execution condition for conditional switching is met.

[0015] According to another aspect, a non-transitory computer-readable medium comprising program instructions is provided, which, when executed by an apparatus, causes the apparatus to at least perform: determining one or more configurations for conditional switching of a user equipment, wherein the configuration in the one or more configurations comprises at least: a primary cell group configuration of a target primary cell of a primary cell group, and a secondary cell group configuration of a target primary cell of a secondary cell group, and wherein the configuration is associated with at least one execution condition for the conditional switching, and at least one access condition for the target primary cell of the secondary cell group; and sending one or more configurations, wherein the one or more configurations indicate: delaying access to the target primary cell of the secondary cell group based on determining that at least one access condition is not met when detecting that at least one execution condition for the conditional switching is met. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Hereinafter, various example embodiments will be described in more detail with reference to the accompanying drawings, in which

[0017] Figure 1 An example of a cellular communication network is illustrated;

[0018] Figure 2 An example of a wireless communication system is illustrated;

[0019] Figure 3 A signaling diagram is illustrated;

[0020] Figure 4 A signaling diagram is illustrated;

[0021] Figure 5 A signaling diagram is illustrated;

[0022] Figure 6 A signaling diagram is illustrated;

[0023] Figure 7 A signaling diagram is illustrated;

[0024] Figure 8 A signaling diagram is illustrated;

[0025] Figure 9 A signaling diagram is illustrated;

[0026] Figure 10 A flow chart is illustrated;

[0027] Figure 11 A flow chart is illustrated;

[0028] Figure 12 An example of an apparatus is illustrated; and

[0029] Figure 13 An example of an apparatus is illustrated. DETAILED DESCRIPTION

[0030] The following embodiments are illustrative. Although the specification may refer to "one," "an," or "some" embodiments at several locations in the text, this does not necessarily mean that each reference is to the same embodiment(s) or that a particular feature applies only to a single embodiment. Individual features of different embodiments may also be combined to provide further embodiments.

[0031] In the following, different example embodiments will be described using radio access architectures based on Long Term Evolution Advanced (LTE-Advanced, LTE-A), New Radio (NR, 5G), beyond 5G or sixth generation (6G) as examples of access architectures to which example embodiments may be applied, without limiting the example embodiments to such architectures. It will be clear to a person skilled in the art that, by appropriately adjusting parameters and procedures, example embodiments may also be applied to other types of communication networks with appropriate components. Some examples of other options for suitable systems may be Universal Mobile Telecommunications System (UMTS) Radio Access Network (UTRAN or E-UTRAN), Long Term Evolution (LTE, which is essentially the same as E-UTRA), Wireless Local Area Network (WLAN or Wi-Fi), Worldwide Interoperability for Microwave Access (WiMAX), Personal Communications Service (PCS), Wideband Code Division Multiple Access (WCDMA), systems using Ultra-Wideband (UWB) technology, sensor networks, Mobile Ad Hoc Networks (MANETs), and Internet Protocol Multimedia Subsystem (IMS), or any combination thereof.

[0032] Figure 1 An example of a simplified system architecture is depicted, showing some elements and functional entities, which are all logical units, the implementation of which may differ from what is shown. Figure 1 The connections shown are logical connections; the actual physical connections may be different. It will be clear to those skilled in the art that the system may also include in addition to Figure 1 Other functions and structures than those shown.

[0033] However, the exemplary embodiments are not limited to the systems given as examples, and a person skilled in the art may apply the solution to other communication systems having the necessary properties.

[0034] Figure 1 The example of FIG. 1 shows a portion of an exemplary radio access network.

[0035] Figure 1User equipment 100 and 102 are shown, which are configured to wirelessly connect to an access node (AN) 104 (such as an evolved Node B (abbreviated eNB or eNodeB) or a next-generation Node B (abbreviated gNB or gNodeB)) providing the radio cell over one or more communication channels in the radio cell. The physical link from the user equipment to the access node may be referred to as an uplink (UL) or reverse link, while the physical link from the access node to the user equipment may be referred to as a downlink (DL) or forward link. The user equipment may also communicate directly with another user equipment via sidelink (SL) communications. It will be appreciated that an access node or its functionality may be implemented using any entity such as a node, host, server, or access point suitable for such purpose.

[0036] The communication system may include more than one access node, in which case the access nodes may also be configured to communicate with each other via wired or wireless links designed for this purpose. These links may be used for signaling purposes as well as for routing data from one access node to another access node. An access node may be a computing device configured to control the radio resources of the communication system to which it is coupled. An access node may also be referred to as a base station, a base transceiver station (BTS), an access point, or any other type of interface device, including a relay station capable of operating in a wireless environment. An access node may include or be coupled to a transceiver. From the transceiver of the access node, a connection to an antenna unit may be provided, which establishes a two-way radio link to a user equipment. The antenna unit may include multiple antennas or antenna elements. The access node may also be connected to a core network 110 (CN or next generation core NGC). Depending on the deployed technology, the counterpart to which the access node can be connected on the CN side can be a serving gateway (S-GW, which routes and forwards user data packets), a packet data network gateway (P-GW) for providing user equipment with connectivity to external packet data networks, a user plane function (UPF), a mobility management entity (MME), or an access and mobility management function (AMF), etc.

[0037] The user equipment illustrates one type of apparatus to which resources on the air interface may be allocated and assigned, and thus any features of the user equipment described herein may be implemented with a corresponding apparatus, such as a relay node.

[0038] An example of such a relay node may be a layer 3 relay towards an access node (self-backhaul relay). A self-backhaul relay node may also be referred to as an integrated access and backhaul (IAB) node. An IAB node may comprise two logical parts: a mobile terminal (MT) part, which is responsible for the backhaul link(s) (i.e., the link(s) between the IAB node and the donor node (also referred to as the parent node)); and a distributed unit (DU) part, which is responsible for the access link(s) (i.e., the sub-link(s) between the IAB node and the user equipment(s) and / or between the IAB node and other IAB nodes (multi-hop scenario)).

[0039] Another example of such a relay node may be a layer 1 relay known as a repeater.A repeater may amplify signals received from an access node and forward them to a user equipment, and / or amplify signals received from a user equipment and forward them to an access node.

[0040] User equipment may also be referred to as a subscriber unit, mobile station, remote terminal, access terminal, user terminal, terminal device, or user equipment (UE), to name just a few names or devices. User equipment may refer to a portable computing device, including wireless mobile communication devices operating with or without a subscriber identity module (SIM), including but not limited to the following types of devices: mobile stations (mobile phones), smartphones, personal digital assistants (PDAs), cell phones, devices using wireless modems (alarm or measurement devices, etc.), laptop computers and / or touch screen computers, tablet computers, game consoles, notebook computers, multimedia devices, reduced capability (RedCap) devices, wireless sensor devices, or any device integrated into a vehicle.

[0041] It should be understood that a user device may also be an almost exclusively uplink-only device, an example of which may be a camera or camcorder that loads images or video clips to a network. A user device may also be a device capable of operating in an Internet of Things (IoT) network, in which case an object may have the ability to transmit data over a network without requiring human-to-human or human-to-computer interaction. User devices may also utilize the cloud. In some applications, a user device may comprise a small portable or wearable device (such as a watch, headphones, or glasses) with a radio component, and computing may be performed in the cloud or in another user device. A user device (or, in some example embodiments, a layer 3 relay node) may be configured to perform one or more of the user device functions.

[0042] The various techniques described in this article can also be applied to cyber-physical systems (CPS) (systems of cooperating computing elements that control physical entities). CPS can enable the implementation and utilization of large numbers of interconnected ICT devices (sensors, actuators, processors, microcontrollers, etc.) in physical objects at different locations. Mobile cyber-physical systems are a subcategory of cyber-physical systems in which the physical systems in question can have inherent mobility. Examples of mobile physical systems include mobile robots and electronic devices transported by humans or animals.

[0043] Furthermore, although these devices are depicted as a single entity, different units, processors and / or memory units may be implemented. Figure 1 Not all are shown).

[0044] 5G enables the use of multiple-input multiple-output (MIMO) antennas, many more base stations or nodes than LTE (the so-called small cell concept), including macro sites operating in cooperation with smaller sites, and the use of various radio technologies depending on service requirements, use cases and / or available spectrum. 5G mobile communications can support a wide range of use cases and related applications, including video streaming, augmented reality, different data sharing methods and various forms of machine-type applications, such as (massive) machine-type communications (mMTC), including vehicle safety, different sensors and real-time control. 5G can have multiple radio interfaces, namely below 6 GHz, cmWave and mmWave, and can also be integrated with existing traditional radio access technologies (such as LTE). For example, at least in the early stages, integration with LTE can be implemented as a system where macro coverage can be provided by LTE and 5G radio interface access can come from small cells by aggregation to LTE. In other words, 5G can support both inter-RAT operability (such as LTE-5G) and inter-RI operability (inter-radio interface operability, such as below 6 GHz-cmWave-mmWave). One of the concepts being considered for use in 5G networks may be network slicing, in which multiple independent and dedicated virtual subnets (network instances) can be created within essentially the same infrastructure to run services with different requirements for latency, reliability, throughput, and mobility.

[0045] The current architecture in LTE networks can be fully distributed in the radio and fully centralized in the core network. Low-latency applications and services in 5G may require content to be close to the radio, leading to local breakthroughs and multi-access edge computing (MEC). 5G can enable analysis and knowledge generation at the data source. This approach may require the use of resources that may not be continuously connected to the network, such as laptops, smartphones, tablets, and sensors. MEC provides a distributed computing environment for application and service hosting. It can also have the ability to store and process content close to cellular subscribers for faster response times. Edge computing can cover a wide range of technologies, such as wireless sensor networks, mobile data collection, mobile signature analysis, collaborative distributed peer-to-peer networking and processing (also categorized as local cloud / fog computing and grid / grid computing), dew computing, mobile edge computing, cloudlets, distributed data storage and retrieval, autonomous self-healing networks, remote cloud services, augmented and virtual reality, data caching, the Internet of Things (massive connectivity and / or latency-critical), and critical communications (autonomous vehicles, traffic safety, real-time analytics, time-critical control, and healthcare applications).

[0046] The communication system may also be capable of communicating with, or utilizing services provided by, one or more other networks 113, such as a public switched telephone network or the Internet. The communication network may also be capable of supporting the use of cloud services, for example, at least a portion of the core network operations may be performed as a cloud service (this is in the context of Figure 1 (represented by "cloud" 114 in FIG. 1 ). The communication system may also include a central control entity or the like to provide facilities for the networks of different operators to collaborate, for example, in terms of spectrum sharing.

[0047] The access node can also be split into: a radio unit (RU), which includes a radio transceiver (TRX), i.e., a transmitter (Tx) and a receiver (Rx); one or more distributed units (DU) 105, which can be used for so-called layer 1 (L1) processing and real-time layer 2 (L2) processing; and a central unit (CU) 108 (also called a centralized unit), which can be used for non-real-time L2 and layer 3 (L3) processing. The CU 108 can be connected to one or more DUs 105, for example, via an F1 interface. Such a split can enable centralization of the CU relative to the cell site and the DU, while the DU can be more distributed and can even be retained at the cell site. The CU and DU together can also be referred to as a baseband or baseband unit (BBU). The CU and DU can also be included in a radio access point (RAP).

[0048] The CU 108 may be defined as a logical node that hosts the higher layer protocols of the access node, such as radio resource control (RRC), service data adaptation protocol (SDAP), and / or packet data convergence protocol (PDCP). The DU 105 may be defined as a logical node that hosts the radio link control (RLC), medium access control (MAC), and / or physical (PHY) layers of the access node. The operation of the DU may be at least partially controlled by the CU. The CU may include a control plane (CU-CP), which may be defined as a logical node that hosts the control plane portion of the RRC and PDCP protocols for the CU of the access node. The CU may also include a user plane (CU-UP), which may be defined as a logical node that hosts the user plane portion of the PDCP protocol and the SDAP protocol for the CU of the access node.

[0049] The cloud computing platform can also be used to run the CU 108 and / or DU 105. The CU can run in the cloud computing platform, which can be called a virtualized CU (vCU). In addition to the vCU, a virtualized DU (vDU) can also run in the cloud computing platform. In addition, there can also be a combination in which the DU can use a so-called bare metal solution, such as an application-specific integrated circuit (ASIC) or a customer-specific standard product (CSSP) system-on-chip (SoC) solution. It should also be understood that the functional distribution between the above-mentioned access node units, or different core network operations and access node operations can be different.

[0050] Edge cloud can be introduced into the radio access network (RAN) by leveraging network function virtualization (NFV) and software defined networking (SDN). The use of edge cloud can mean that access node operations are at least partially performed in a server, host or node that is operationally coupled to a remote radio head (RRH) or radio unit (RU) or access node including radio components. Node operations can also be distributed among multiple servers, nodes or hosts. The application of cloudRAN architecture enables RAN real-time functions to be performed on the RAN side (e.g., in DU 105) and enables non-real-time functions to be performed in a centralized manner (e.g., in CU 108).

[0051] It should also be understood that the functional distribution between core network operations and access node operations may be different from LTE, or even non-existent. Some other technological advancements that may be used include big data and all-IP, which may change the way networks are constructed and managed. 5G (or New Radio NR) networks can be designed to support multiple hierarchical structures, where MEC servers can be placed between the core and access nodes. It should be understood that MEC can also be applied to 4G networks.

[0052] 5G can also utilize non-terrestrial communications (e.g., satellite communications) to enhance or supplement the coverage of 5G services, for example by providing backhaul. Possible use cases could be providing service continuity for machine-to-machine (M2M) or Internet of Things (IoT) devices or for passengers on board, or ensuring service availability for critical communications and future rail / maritime / aeronautical communications. Satellite communications can utilize geostationary orbit (GEO) satellite systems as well as low Earth orbit (LEO) satellite systems, in particular mega-constellations (systems in which hundreds of (nano) satellites are deployed). A given satellite 106 in a mega-constellation can cover several satellite-enabled network entities creating a terrestrial cell. A terrestrial cell can be created by a terrestrial relay node or by an access node 104 located on the ground or in a satellite.

[0053] 6G networks are expected to utilize flexible decentralized and / or distributed computing systems and architectures, as well as ubiquitous computing. Based on mobile edge computing, artificial intelligence, short packet communications, and blockchain technologies, they will enable local spectrum licensing, spectrum sharing, infrastructure sharing, and intelligent automated management. Key features of 6G may include intelligent interconnected management and control capabilities, programmability, integrated sensing and communications, a reduced energy footprint, trustworthy infrastructure, scalability, and affordability. Furthermore, 6G targets new use cases, including integrating positioning and sensing capabilities into system definitions to unify user experiences across the physical and digital worlds.

[0054] It is clear to those skilled in the art that the depicted system is only an example of a portion of a radio access system, and in practice, the system may include multiple access nodes, user equipment may access multiple radio cells, and the system may also include other devices, such as physical layer relay nodes or other network elements. At least one of the access nodes may be a home eNodeB or a home gNodeB.

[0055] Furthermore, in a geographical area of ​​a radio communication system, a plurality of different kinds of radio cells and a plurality of radio cells may be provided. A radio cell may be a macro cell (or umbrella cell), which may be a large cell with a diameter of up to tens of kilometres, or a smaller cell, such as a micro cell, a femto cell or a pico cell. Figure 1 (a plurality of) access nodes can provide any kind of these cells. A cellular radio system can be implemented as a multi-layer network comprising several kinds of radio cells. In a multi-layer network, one access node can provide one or more kinds of radio cells, and thus providing such a multi-layer network structure may require multiple access nodes.

[0056] In order to meet the requirements of improving the deployment and performance of communication systems, the concept of "plug and play" access nodes can be introduced. In addition to the home eNodeB or home gNodeB, a network that can use "plug and play" access nodes can also include a home NodeB gateway or HNB-GW ( Figure 1 (not shown). The HNB-GW, which may be installed in the operator's network, may aggregate services from a large number of home eNodeBs or home gNodeBs back to the core network.

[0057] Figure 2 The diagram illustrates an example of a wireless communication system 200 to which some example embodiments may be applied. At least part of the wireless communication system 200 may be configured to implement dual connectivity (DC). Dual connectivity enables a UE 203 to be connected to two cell groups simultaneously: a primary cell group (MCG) 210 and a secondary cell group (SCG) 220. Dual connectivity may be combined with carrier aggregation, and there may be multiple cells in a given cell group (e.g., one cell per aggregated carrier). The two cell groups may be associated with different RAN nodes 201, 202 (i.e., access nodes). The two cell groups may be based on different radio access technologies (e.g., LTE and 5G), or they may be based on the same radio access technology. Here, the term "cell" refers to a radio cell.

[0058] The MCG 210 is a set of serving cells associated with a master node (MN) 201 (i.e., a RAN node that provides a control plane connection to the core network). The MCG 210 includes a primary cell (PCell) 211 (i.e., the primary serving cell of the MCG 210), and optionally one or more secondary cells (SCells) 212. The PCell 211 is a cell operating on a primary frequency that can be used for initial access under the MCG 210. The SCell is a cell operating on a secondary frequency that can be configured after an RRC connection is established and can be used to provide additional radio resources. A given serving cell can be associated with physical resources that can come from one or more actual transmission and reception points (TRPs), and the UE 203 can also be configured to utilize one or more TRPs. In this case, the UE 203 can use resources from more than one cell for each aggregated carrier or frequency.

[0059] The SCG 220 is a set of serving cells associated with a secondary node (SN) 202 (i.e., a RAN node that provides additional resources to UEs). The SCG 220 includes a PSCell 221 (i.e., the primary serving cell of the SCG 220) and optionally one or more SCells 222. The PSCell 221 is a cell that can be used for initial access under the SCG 220.

[0060] In order to provide continuous service to the user of a mobile UE, the UE may perform a handover procedure, which may also be referred to as a handover, to change from one cell to another. For example, when a UE with an ongoing call or data session leaves the area covered by the source cell and enters the area covered by a neighboring cell, the session may be handed over from the source cell to the neighboring cell to avoid termination or interruption of the session when the UE moves out of the range of the source cell.

[0061] Some example embodiments relate to enhancements of Conditional Handover (CHO) with SCG configuration.

[0062] The CHO procedure has been introduced in NR Release 16 to improve mobility robustness. Conditional handover can be defined as a handover performed by the UE when one or more handover execution conditions are met. In other words, the UE receives a handover command with a CHO configuration indicating one or more handover execution conditions, but the UE does not execute the handover command until the one or more execution conditions are met. The UE may start evaluating the execution condition(s) after receiving the CHO configuration from the source gNB and stop evaluating the execution condition(s) after the handover is executed. One advantage of CHO is that it improves mobility robustness by reducing the number of radio link failures and handover failures compared to traditional handover. This is achieved by decoupling the handover execution phase from the preparation phase, enabling the UE to receive the handover command early, when the radio link to the source cell is still sufficient, and perform the handover later, when the radio link to the target cell is strong enough.

[0063] In the case of CHO, the network can prepare multiple target cells, where a given conditional handover reconfiguration is associated with at least one CHO execution condition evaluated by the UE. The CHO execution condition refers to a measurement ID that associates a measurement object with a reporting configuration and is configured by the source gNB. The reporting configuration defines the measurement event (e.g., A3 or A5) that triggers CHO execution. One or more reference signal types can be supported, and one or more triggering quantities can be configured to evaluate the CHO execution condition for a given candidate cell. The one or more triggering quantities can include, for example, reference signal received power (RSRP), reference signal received quality (RSRQ), and / or signal-to-interference-plus-noise ratio (SINR). As long as the CHO execution condition is met, the corresponding target configuration is selected, and handover to the selected target cell is performed.

[0064] CHO event A3 indicates that the triggering amount of the CHO candidate cell indicated in the CHO configuration exceeds the triggering amount of the serving cell with a certain offset within a specific triggering time (TTT) period.

[0065] CHO event A5 indicates that the triggering amount of the serving cell becomes lower than a first threshold, and the triggering amount of the CHO candidate cell indicated in the CHO configuration exceeds a second threshold within a certain TTT period.

[0066] In CHO, after sending RRC reconfiguration or receiving RRC reconfiguration complete, the source gNB can start early forwarding of user plane data to the prepared target cell. As communication with the UE continues after sending RRC reconfiguration, the source gNB sends an Early SN State Transfer message to the target gNB, which indicates the data packets that the UE has received and that should be deleted from the buffer maintained for the given prepared target PCell.

[0067] In NR Release 17, signaling enhancements for supporting CHO with SCG have been specified, where a target MN receiving a handover request from a source MN can add and prepare a target SN, i.e., handover to a DC connection.

[0068] In this case, the CHO configuration provided by the target MN back to the source MN may include: the MCG configuration to be applied for the target PCell and the SCG configuration to be applied for the target PSCell (i.e., the primary serving cell of the SCG). (Multiple) CHO execution conditions may be evaluated by the UE based on measurements of the target PCell, i.e., measurements of the target PSCell are not considered in the evaluation. When (multiple) CHO execution conditions are met, the UE may perform random access to the target PCell and the target PSCell.

[0069] MCG configuration is the cell group configuration in RRCReconfiguration, where MCG configuration includes the SpCell configuration and / or SCell configuration of the MCG. SCG configuration is the cell group configuration in RRCReconfiguration, where SCG configuration includes the SpCell configuration and / or SCell configuration of the SCG. SpCell (special cell) refers to the primary cell of the MCG or the primary cell of the SCG. For example, MCG configuration or SCG configuration may include:

[0070]

[0071] Given the time between CHO preparation and execution, the radio signal quality of the target PSCell may be insufficient when CHO is executed, which may lead to SCG failure and interruption on the SCG radio bearer, with the interruption time being as long as 500ms or longer (depending on the T304 value that supervises random access to the target PSCell). This problem will be solved in NR Release 18 by: 1) providing PSCell access conditions (separate from the CHO execution conditions) to decide whether to access the target PSCell / SN, and 2) allowing the target MN to prepare more than one candidate target PSCell / SN. For example, the PSCell access conditions (e.g., conditional PSCell addition change CPAC conditions) can be evaluated using target PSCell measurements.

[0072] For example, the PSCell access condition may refer to an A3 or A5 event related to the PSCell, and the CHO execution condition may refer to an A3 or A5 event related to the PCell.

[0073] To overcome the above issues, the UE should have already started evaluating the access conditions of the prepared target PSCell(s) when receiving the CHO configuration. Therefore, the UE can perform measurements on the prepared target PCell and the target PSCell simultaneously and consider their radio link strength / quality when deciding on CHO execution.

[0074] When evaluating the CHO execution condition, if the prepared PSCell access condition of the target PSCell is satisfied, the UE waits and does not perform random access on the target PSCell until the CHO execution condition of the corresponding target PCell is satisfied.

[0075] When the CHO execution conditions are met, it may still be useful to check whether the leave conditions of the target PSCell (whose PSCell access conditions were previously met) are not met to ensure that the radio signal of the target PSCell is still sufficient. If the leave conditions are not met, the UE performs CHO and performs random access to the target PCell and the selected target PSCell.

[0076] Otherwise, if the leave condition is met (or if none of the target PSCells prepared when evaluating the CHO condition meets the PSCell access condition), the UE may perform MCG configuration and perform random access to the target MN, but not to any target PSCell. Here, the UE may inform the MN that none of the prepared target PSCells meets the PSCell access condition. Using this information, the MN may reconfigure the UE by, for example, remapping the SN radio bearer to the MN. It should be noted that delaying PCell access until one of the PSCell access conditions is met may not be useful, as this may result in a radio link failure (RLF).

[0077] If the PSCell access condition is not met when the CHO execution condition is met, the UE may perform CHO configuration (including MCG and SCG configuration) but only perform random access to the target PCell, i.e., the UE may skip random access to the target PSCell. The UE may indicate to the target MN that the PSCell condition is not met.

[0078] After the UE completes random access to the target PCell, the UE may release all other CHO configurations (which may also include the prepared SCG configuration of the target PSCell).

[0079] After receiving an indication from the UE that the PSCell access conditions are not met, the target MN may reconfigure the UE, which may increase signaling overhead and latency. For example, to configure a new SCG, the target MN may need to contact the SN via the Xn interface (2Xn signaling) and reconfigure the UE using RRC reconfiguration. This delays the UE's PSCell access, which may result in service interruption or throughput loss.

[0080] After the CHO execution conditions are met and random access to the target PCell (but not yet to the target PSCell) is performed, some example embodiments may address the above issues by using an SCG configuration within a CHO configuration (including an MCG configuration and an SCG configuration).

[0081] In an example embodiment, if the PSCell access condition is not met when the CHO execution condition is met, the UE applies the CHO configuration (MCG and SCG configuration) and performs random access to the target PCell, but delays random access to the target PSCell. The UE continues to evaluate the PSCell access condition for a period of time that can be pre-configured by the network.

[0082] In the first option, if the PSCell access conditions are met within the time period, the UE can perform random access to the target PSCell. Otherwise, if the PSCell access conditions are not met within the time period, the UE can notify the target MN that the second PSCell access conditions are not met within the configured time period. After receiving this indication from the UE, the network can reconfigure the UE. In other words, in the first option, when the CHO execution conditions are met, the UE can apply the SCG configuration, but the UE delays access to the PSCell.

[0083] Alternatively, in the second option, if the PSCell access conditions are met within a configured time period, the UE may apply 1) the SCG configuration, as the MCG configuration may be the same in multiple CHO configurations, or 2) both the MCG configuration and the SCG configuration, and send an indication to the network. In other words, in the second option, when the CHO execution conditions are met, the UE may not have applied any SCG configuration, and the UE waits to access the PSCell and simultaneously applies the SCG configuration. Applying the MCG configuration means changing the UE parameters to comply with the parameters provided by the MCG configuration. Applying the SCG configuration means changing the UE parameters to comply with the parameters provided by the SCG configuration.

[0084] In case the timer is not configured, the network may signal the UE to release the maintained configuration.

[0085] In another example embodiment, after the target MN receives an indication that the PSCell conditions are not met when the CHO conditions are met, the target MN may not release any SCG configuration. The target MN may configure the UE to report measurements related to candidate PSCells. If the measurement conditions for adding any PSCell are met, the network may use the stored SCG configuration to trigger the PSCell addition.

[0086] However, some example embodiments are described below using the principles and terminology of 5G technology without limiting the example embodiments to 5G communication systems.

[0087] Figure 3 A signaling diagram according to an example embodiment is illustrated.

[0088] Initially, the UE may be configured with measurement configuration and report measurements of neighboring PSCells and possible PSCells.The source MN may determine that CHO preparation of the UE is necessary.

[0089] refer to Figure 3 In block 301, the source MN sends a CHO handover request to the target MN. In other words, the source MN indicates the CHO request to the target MN using measurements of the target PSCell.

[0090] In block 302, the target MN prepares target PSCells (eg, PSCell-1 and PSCell-2) by sending an SN add request to the target SN.

[0091] In block 303, the target SN sends an acknowledgement (ACK) of the SN add request to the target MN.

[0092] In block 304, each SCG configuration of the target PSCell may be configured in a separate CHO configuration at the target MN. For example, the target MN may determine a first CHO configuration of PCell-1 and PSCell-1, and a second CHO configuration of PCell-1 and PSCell-2. Here, PCell refers to the primary cell of the primary cell group, and PSCell refers to the primary cell of the secondary cell group.

[0093] In other words, the target MN can determine one or more configurations of conditional switching of the UE, wherein a given configuration among the one or more configurations includes at least: a primary cell group configuration of a target primary cell of a primary cell group, and a secondary cell group configuration of a target primary cell of a secondary cell group, and wherein the configuration is associated with at least one execution condition of the conditional switching, and at least one access condition of the target primary cell of the secondary cell group.

[0094] In block 305, the target MN sends an ACK for the handover request to the source MN. The target MN also sends one or more CHO configurations to the source MN, wherein the one or more configurations indicate delaying access to a target primary cell of the secondary cell group based on determining that at least one access condition is not satisfied when detecting that at least one execution condition of the conditional handover is satisfied.

[0095] In box 306, the source MN performs RRC reconfiguration to configure one or more CHO configurations and related conditions (i.e., at least one CHO execution condition and at least one PSCell access condition) for the UE. In other words, the UE receives one or more CHO configurations and related conditions. The UE can be configured to maintain only the selected SCG configuration. The selected SCG configuration refers to the SCG configuration for which the CHO execution condition is met. Here, maintenance may mean that the UE stores the selected SCG configuration in its memory, and the UE may discard (multiple) other SCG configurations. In addition, the UE is configured with a maintenance timer to not apply the SCG configuration and delay PSCell access after CHO execution. The access may mean random access to the PSCell. The CHO configuration may be sent together with a handover command for conditional handover.

[0096] In block 307, the UE sends an RRC reconfiguration complete message to the source MN to confirm the successful completion of the RRC reconfiguration.

[0097] In block 308 , the UE determines that at least one CHO execution condition of the target PCell is satisfied, and the UE performs a PCell change to the target PCell.

[0098] In block 309, the UE maintains or stores the selected SCG configuration (e.g., for PSCell-1) and, upon detecting that at least one execution condition for conditional handover is satisfied, starts a maintenance timer, wherein the timer is configured to expire after a time period. In other words, the UE may only maintain a single SCG configuration in one of the CHO configurations.

[0099] In block 310, the UE performs a random access procedure on the target mobile node to access the target PCell. In other words, the UE accesses the target primary cell of the primary cell group upon detecting that at least one execution condition is satisfied. However, upon determining that at least one access condition is not satisfied upon detecting that at least one execution condition for conditional handover is satisfied, the UE delays accessing the target primary cell of the secondary cell group.

[0100] In block 311, the target MN starts a maintenance timer at the target MN in a random access procedure, for example, upon receiving a random access preamble from a UE.

[0101] In block 312, after the random access procedure is completed, the target MN initiates an RRC reconfiguration procedure towards the UE.

[0102] In block 313 , the UE continues to evaluate at least one PSCell access condition.

[0103] In block 314, based on the evaluation, the UE determines that at least one PSCell-1 access condition is met while the timer is configured and running. In other words, the UE monitors at least one PSCell access condition and detects that at least one access condition is met before the maintenance timer expires.

[0104] In block 315, the UE applies the SCG configuration (e.g., for PSCell-1) and performs a random access procedure to access the PSCell. In other words, before the maintenance timer expires, upon detecting that at least one access condition is met, the UE accesses the target primary cell of the secondary cell group based on the stored secondary cell group configuration.

[0105] In block 316, the UE sends the SN RRC reconfiguration to the target MN.

[0106] In block 317, the target MN stops the maintenance timer upon receiving the SN RRC reconfiguration.

[0107] In block 318, the target MN sends an SN Modification Confirm (RRC Reconfiguration Complete) message to the target SN.

[0108] Figure 4 A signaling diagram according to an example embodiment is illustrated.

[0109] Initially, the UE may be configured with measurement configuration and report measurements of neighboring PSCells and possible PSCells.The source MN may determine that CHO preparation of the UE is necessary.

[0110] refer to Figure 4 In block 401, the source MN sends a CHO handover request to the target MN. In other words, the source MN indicates the CHO request to the target MN using measurements of the target PSCell.

[0111] In block 402, the target MN prepares target PSCells (eg, PSCell-1 and PSCell-2) by sending an SN add request to the target SN.

[0112] In block 403, the target SN sends an acknowledgement (ACK) of the SN add request to the target MN.

[0113] In block 404, each SCG configuration of the target PSCell can be configured in a separate CHO configuration at the target MN. For example, the target MN can determine a first CHO configuration for PCell-1 and PSCell-1, and a second CHO configuration for PCell-1 and PSCell-2. The source MN indicates to the target MN the timers to be configured for the UE. Here, PCell refers to the primary cell of the primary cell group, and PSCell refers to the primary cell of the secondary cell group.

[0114] In other words, the target MN can determine one or more configurations of conditional switching of the UE, wherein a given configuration among the one or more configurations includes at least: a primary cell group configuration of a target primary cell of a primary cell group, and a secondary cell group configuration of a target primary cell of a secondary cell group, and wherein the configuration is associated with at least one execution condition of the conditional switching, and at least one access condition of the target primary cell of the secondary cell group.

[0115] In block 405, the target MN sends an ACK for the handover request to the source MN. The target MN also sends one or more CHO configurations to the source MN, wherein the one or more configurations indicate delaying access to a target primary cell of the secondary cell group based on determining that at least one access condition is not satisfied when detecting that at least one execution condition of the conditional handover is satisfied.

[0116] In block 406, the source MN performs RRC reconfiguration to configure one or more CHO configurations and related conditions (i.e., at least one CHO execution condition and at least one PSCell access condition) for the UE. In other words, the UE receives the one or more CHO configurations and related conditions. The UE may be configured to maintain only the selected SCG configuration. In addition, the UE is configured with a maintenance timer to delay PSCell access after CHO execution. This access may represent a random access to the PSCell. The CHO configuration may be sent together with a handover command for conditional handover.

[0117] In block 407, the UE sends an RRC reconfiguration complete message to the source MN to confirm the successful completion of the RRC reconfiguration.

[0118] In block 408 , the UE determines that at least one CHO execution condition of the target PCell is satisfied, and the UE performs a PCell change to the target PCell.

[0119] In block 409, the UE maintains or stores the selected SCG configuration (e.g., for PSCell 1) and, upon detecting that at least one execution condition for conditional handover is satisfied, starts a maintenance timer, wherein the timer is configured to expire after a time period. In other words, the UE may maintain only a single SCG configuration in one of the CHO configurations.

[0120] In block 410, the UE performs a random access procedure on the target mobile node to access the target PCell. In other words, the UE accesses the target primary cell of the primary cell group upon detecting that at least one execution condition is satisfied. However, upon determining that at least one access condition is not satisfied upon detecting that at least one execution condition for conditional handover is satisfied, the UE delays accessing the target primary cell of the secondary cell group.

[0121] In block 411, the target MN may start a timer upon detecting that the UE is connected to a target primary cell associated with the target MN, wherein the timer is configured to expire after a time period. The target MN may start the timer during a random access procedure, for example, upon receiving a random access preamble from the UE. The timer may correspond to a maintenance timer of the UE.

[0122] In block 412, after the random access procedure is completed, the target MN initiates an RRC reconfiguration procedure towards the UE.

[0123] In block 413 , the UE continues to evaluate at least one PSCell access condition.

[0124] In block 414, the UE detects that the maintenance timer expires and the UE determines that at least one access condition is not satisfied within a configured time period. In other words, the UE monitors at least one PSCell access condition and at least one access condition is not satisfied before the timer expires.

[0125] In block 415, the UE may optionally send an indication to the target MN associated with the target PSCell indicating that at least one access condition is not satisfied within a configured time period.

[0126] In block 416, based on the indication or the expiration of a timer started by the target MN, the target MN releases (ie, deletes) the maintained (stored) SCG configuration (eg, for PSCell-1).

[0127] In block 417, the target MN sends an RRC reconfiguration message to the UE to remap the SCG radio bearers to the MCG.

[0128] In block 418, the UE sends an RRC reconfiguration complete message to the target MN to confirm the successful completion of the RRC reconfiguration (ie, remapping).

[0129] Figure 5 A signaling diagram according to an example embodiment is illustrated.

[0130] Initially, the UE may be configured with measurement configuration and report measurements of neighboring PSCells and possible PSCells.The source MN may determine that CHO preparation of the UE is necessary.

[0131] refer to Figure 5 In block 501, the source MN sends a CHO handover request to the target MN. In other words, the source MN indicates the CHO request to the target MN using measurements of the target PSCell.

[0132] In block 502, the target MN prepares target PSCells (eg, PSCell-1 and PSCell-2) by sending an SN add request to the target SN.

[0133] In block 503, the target SN sends an acknowledgement (ACK) of the SN add request to the target MN.

[0134] In block 504, each SCG configuration of the target PSCell may be configured in a separate CHO configuration at the target MN. For example, the target MN may determine a first CHO configuration of PCell-1 and PSCell-1, and a second CHO configuration of PCell-1 and PSCell-2. Here, PCell refers to the primary cell of the primary cell group, and PSCell refers to the primary cell of the secondary cell group.

[0135] In other words, the target MN can determine one or more configurations of conditional switching of the UE, wherein a given configuration among the one or more configurations includes at least: a primary cell group configuration of a target primary cell of a primary cell group, and a secondary cell group configuration of a target primary cell of a secondary cell group, and wherein the configuration is associated with at least one execution condition of the conditional switching, and at least one access condition of the target primary cell of the secondary cell group.

[0136] In block 505, the target MN sends an ACK for the handover request to the source MN. The target MN also sends one or more CHO configurations to the source MN, wherein the one or more configurations indicate delaying access to a target primary cell of the secondary cell group based on determining that at least one access condition is not satisfied when detecting that at least one execution condition of the conditional handover is satisfied.

[0137] In block 506, the source MN performs RRC reconfiguration to configure one or more CHO configurations and related conditions (i.e., at least one CHO execution condition and at least one PSCell access condition) for the UE. In other words, the UE receives one or more CHO configurations and related conditions. The CHO configuration may be sent together with a handover command for conditional handover. The UE is configured to maintain at least all SCG configurations in the CHO configuration after performing a PCell change. The UE may also be configured to maintain all MCG configurations after performing a PCell change. The UE may be configured to maintain these configurations with respect to a maintenance timer, i.e., to delete the maintained configuration when the timer expires.

[0138] In block 507, the UE sends an RRC reconfiguration complete message to the source MN to confirm the successful completion of the RRC reconfiguration.

[0139] In block 508 , the UE determines that at least one CHO execution condition of the target PCell is satisfied, and the UE performs a PCell change to the target PCell.

[0140] In block 509, the UE maintains or stores at least the SCG configuration and, upon detecting that at least one execution condition of conditional handover is satisfied, starts a maintenance timer configured to expire after a time period. The UE may also maintain (store) the MCG configuration.

[0141] In block 510, the UE performs a random access procedure on the target mobile node to access the target PCell. In other words, the UE accesses the target primary cell of the primary cell group upon detecting that at least one execution condition is satisfied. However, upon determining that at least one access condition is not satisfied upon detecting that at least one execution condition for conditional handover is satisfied, the UE delays accessing the target primary cell of the secondary cell group.

[0142] In block 511, after the random access procedure is completed, the target MN initiates an RRC reconfiguration procedure towards the UE.

[0143] In block 512, the UE continues to evaluate the PSCell access conditions of the maintained SCG configuration.

[0144] In block 513, based on the evaluation, the UE determines that one of the target PSCells (e.g., PSCell-1) satisfies at least one PSCell access condition while the timer is configured and running. In other words, the UE monitors the PSCell access conditions, and at least one access condition is satisfied before the maintenance timer expires.

[0145] In block 514, based on detecting that at least one access condition is satisfied within the configured time period, the UE applies at least the stored SCG (e.g., PSCell-1) configuration associated with the satisfied at least one access condition. The UE may also apply the stored MCG configuration (if it is stored in block 509).

[0146] In block 515 , the UE performs a random access procedure to access a target PSCell that satisfies at least one access condition.

[0147] In block 516, the UE sends the SN RRC reconfiguration to the target MN.

[0148] In block 517, the target MN stops the timer upon receiving the SN RRC reconfiguration. The target MN may release at least the SCG configuration(s) not applied by the UE (eg, for PSCell-2). The target MN may also release the MCG configuration(s) not applied by the UE.

[0149] In block 518, the target MN sends an SN Modification Confirm (RRC Reconfiguration Complete) message to the target SN.

[0150] Figure 6 A signaling diagram according to an example embodiment is illustrated.

[0151] Initially, the UE may be configured with measurement configuration and report measurements of neighboring PSCells and possible PSCells.The source MN may determine that CHO preparation of the UE is necessary.

[0152] refer to Figure 6 In block 601, the source MN sends a CHO handover request to the target MN. In other words, the source MN indicates the CHO request to the target MN using measurements of the target PSCell.

[0153] In block 602, the target MN prepares target PSCells (eg, PSCell-1 and PSCell-2) by sending an SN add request to the target SN.

[0154] In block 603, the target SN sends an acknowledgement (ACK) of the SN add request to the target MN.

[0155] In block 604, each SCG configuration of the target PSCell may be configured in a separate CHO configuration at the target MN. For example, the target MN may determine a first CHO configuration of PCell-1 and PSCell-1, and a second CHO configuration of PCell-1 and PSCell-2. Here, PCell refers to the primary cell of the primary cell group, and PSCell refers to the primary cell of the secondary cell group.

[0156] In other words, the target MN can determine one or more configurations of conditional switching of the UE, wherein a given configuration among the one or more configurations includes at least: a primary cell group configuration of a target primary cell of a primary cell group, and a secondary cell group configuration of a target primary cell of a secondary cell group, and wherein the configuration is associated with at least one execution condition of the conditional switching, and at least one access condition of the target primary cell of the secondary cell group.

[0157] In block 605, the target MN sends an ACK for the handover request to the source MN. The target MN also sends one or more CHO configurations to the source MN, wherein the one or more configurations indicate delaying access to a target primary cell of the secondary cell group based on determining that at least one access condition is not satisfied when detecting that at least one execution condition of the conditional handover is satisfied.

[0158] In block 606, the source MN performs RRC reconfiguration to configure one or more CHO configurations and related conditions (i.e., at least one CHO execution condition and at least one PSCell access condition) for the UE. In other words, the UE receives one or more CHO configurations and related conditions. The CHO configuration may be sent together with a handover command for conditional handover. The UE is configured to maintain at least all SCG configurations in the CHO configuration after performing a PCell change. The UE may also be configured to maintain all MCG configurations after performing a PCell change. The UE may be configured to maintain these configurations with respect to a maintenance timer, i.e., to delete the maintained configuration when the timer expires.

[0159] In block 607, the UE sends an RRC reconfiguration complete message to the source MN to confirm the successful completion of the RRC reconfiguration.

[0160] In block 608 , the UE determines that at least one CHO execution condition of the target PCell is satisfied, and the UE performs a PCell change to the target PCell.

[0161] In block 609, the UE maintains or stores at least the SCG configuration and, upon detecting that at least one execution condition of conditional handover is satisfied, starts a maintenance timer configured to expire after a time period. The UE may also maintain (store) the MCG configuration.

[0162] In block 610, the UE performs a random access procedure on the target mobile node to access the target PCell. In other words, the UE accesses the target primary cell of the primary cell group upon detecting that at least one execution condition is satisfied. However, upon determining that at least one access condition is not satisfied upon detecting that at least one execution condition for conditional handover is satisfied, the UE delays accessing the target primary cell of the secondary cell group.

[0163] In block 611, after the random access procedure is completed, the target MN initiates an RRC reconfiguration procedure towards the UE.

[0164] In block 612, the UE continues to evaluate the PSCell access conditions of the maintained SCG configuration.

[0165] In block 613, the UE detects that the maintenance timer has expired, and the UE determines that none of the access conditions are met within the configured time period. In other words, the UE monitors the PSCell access conditions, and the access conditions are not met before the timer expires. Upon determining that the access conditions are not met within the configured time period, the UE deletes (i.e., releases) all maintained SCG configurations (e.g., for PSCell-1 and PSCell-2). If the maintained MCG configuration is maintained in block 609, the UE may also delete the maintained MCG configuration.

[0166] In block 614, the UE sends an indication to the target MN indicating that at least one access condition is not satisfied within a configured time period.

[0167] In block 615, based on the indication, the target MN releases at least the maintained SCG configuration (e.g., for PSCell-1 and PSCell-2). If the MCG configuration is maintained, the target MN may also release the maintained MCG configuration other than the executed MCG configuration (i.e., the executed MCF configuration is not released).

[0168] Figure 7 A signaling diagram according to an example embodiment is illustrated. In this example embodiment, no maintenance timer is configured and the network may use dedicated signaling to determine whether to release or retain the maintained configuration on the UE side.

[0169] Initially, the UE may be configured with measurement configuration and report measurements of neighboring PSCells and possible PSCells.The source MN may determine that CHO preparation of the UE is necessary.

[0170] refer to Figure 7 In block 701, the source MN sends a CHO handover request to the target MN. In other words, the source MN indicates the CHO request to the target MN using measurements of the target PSCell.

[0171] In block 702, the target MN prepares target PSCells (eg, PSCell-1 and PSCell-2) by sending an SN add request to the target SN.

[0172] In block 703, the target SN sends an acknowledgement (ACK) of the SN add request to the target MN.

[0173] In block 704, each SCG configuration of the target PSCell may be configured in a separate CHO configuration at the target MN. For example, the target MN may determine a first CHO configuration of PCell-1 and PSCell-1, and a second CHO configuration of PCell-1 and PSCell-2. Here, PCell refers to the primary cell of the primary cell group, and PSCell refers to the primary cell of the secondary cell group.

[0174] In other words, the target MN can determine one or more configurations of conditional switching of the UE, wherein a given configuration among the one or more configurations includes at least: a primary cell group configuration of a target primary cell of a primary cell group, and a secondary cell group configuration of a target primary cell of a secondary cell group, and wherein the configuration is associated with at least one execution condition of the conditional switching, and at least one access condition of the target primary cell of the secondary cell group.

[0175] In block 705, the target MN sends an ACK for the handover request to the source MN. The target MN also sends one or more CHO configurations to the source MN, wherein the one or more configurations indicate delaying access to a target primary cell of the secondary cell group based on determining that at least one access condition is not satisfied when detecting that at least one execution condition of the conditional handover is satisfied.

[0176] In block 706, the source MN performs RRC reconfiguration to configure one or more CHO configurations and related conditions (i.e., at least one CHO execution condition and at least one PSCell access condition) for the UE. In other words, the UE receives one or more CHO configurations and related conditions. The CHO configuration may be sent along with a handover command for conditional handover. The UE is configured to maintain at least all SCG configurations in the CHO configuration after performing a PSCell change. The UE may also be configured to maintain all MCG configurations after performing a PSCell change.

[0177] In block 707, the UE sends an RRC reconfiguration complete message to the source MN to confirm the successful completion of the RRC reconfiguration.

[0178] In block 708 , the UE determines that at least one CHO execution condition of the target PCell is satisfied, and the UE performs a PCell change to the target PCell.

[0179] In block 709, the UE maintains or stores at least the SCG configuration. The UE may also maintain (store) the MCG configuration.

[0180] In block 710, the UE performs a random access procedure on the target mobile node to access the target PCell. In other words, the UE accesses the target primary cell of the primary cell group upon detecting that at least one execution condition is satisfied. However, upon determining that at least one access condition is not satisfied upon detecting that at least one execution condition for conditional handover is satisfied, the UE delays accessing the target primary cell of the secondary cell group.

[0181] In block 711, after the random access procedure is completed, the target MN initiates an RRC reconfiguration procedure towards the UE.

[0182] In block 712, the UE continues to evaluate the PSCell access conditions of the maintained SCG configuration.

[0183] In block 713, the target MN sends an instruction to the UE to release at least the maintained SCG configuration, such as an RRC reconfiguration message. If the MCG configuration is maintained, the target MN may also instruct the UE to release the MCG configuration.

[0184] In block 714, upon receiving the indication (eg, RRC reconfiguration message), the UE deletes (ie, releases) at least the maintained SCG configuration. If the target MN indicates to release the MCG configuration, the UE may also delete the MCG configuration.

[0185] The target MN releases at least the SCG configuration in block 715. The target MN may also release the MCG configuration.

[0186] Figure 8 A signaling diagram according to an example embodiment is shown. In this example embodiment, the trigger is performed from the network side, rather than based on the UE. Therefore, the UE does not have to maintain the configuration because the configuration is maintained on the network side. In this example embodiment, the configuration can be provided to the UE as a conditional PSCell addition change (CPAC).

[0187] Initially, the UE may be configured with measurement configuration and report measurements of neighboring PSCells and possible PSCells.The source MN may determine that CHO preparation of the UE is necessary.

[0188] refer to Figure 8 In block 801, the source MN sends a CHO handover request to the target MN. In other words, the source MN indicates the CHO request to the target MN using measurements of the target PSCell.

[0189] In block 802, the target MN prepares target PSCells (eg, PSCell-1 and PSCell-2) by sending an SN add request to the target SN.

[0190] In block 803, the target SN sends an acknowledgement (ACK) of the SN add request to the target MN.

[0191] In block 804, each SCG configuration of the target PSCell may be configured in a separate CHO configuration at the target MN. For example, the target MN may determine a first CHO configuration of PCell-1 and PSCell-1, and a second CHO configuration of PCell-1 and PSCell-2. Here, PCell refers to the primary cell of the primary cell group, and PSCell refers to the primary cell of the secondary cell group.

[0192] In other words, the target MN can determine one or more configurations of conditional switching of the UE, wherein a given configuration among the one or more configurations includes at least: a primary cell group configuration of a target primary cell of a primary cell group, and a secondary cell group configuration of a target primary cell of a secondary cell group, and wherein the configuration is associated with at least one execution condition of the conditional switching, and at least one access condition of the target primary cell of the secondary cell group.

[0193] In block 805, the target MN sends an ACK for the handover request to the source MN. The target MN also sends one or more CHO configurations to the source MN, wherein the one or more configurations indicate delaying access to a target primary cell of the secondary cell group based on determining that at least one access condition is not satisfied when detecting that at least one execution condition of the conditional handover is satisfied.

[0194] In block 806, the source MN performs RRC reconfiguration to configure one or more CHO configurations and related conditions (i.e., at least one CHO execution condition and at least one PSCell access condition) for the UE. In other words, the UE receives the one or more CHO configurations and related conditions. The CHO configuration(s) may be sent along with a handover command for conditional handover.

[0195] In block 807, the UE sends an RRC reconfiguration complete message to the source MN to confirm the successful completion of the RRC reconfiguration.

[0196] In block 808, the UE determines that at least one CHO execution condition of the target PCell is satisfied, and the UE performs a PCell change to the target PCell. For example, the UE may perform an MCG configuration in the first CHO configuration in response to detecting that at least one CHO execution condition associated with the first CHO configuration is satisfied.

[0197] In block 809, the UE releases or deletes CHO configuration(s) other than the executed CHO configuration. For example, the UE may delete the second CHO configuration (in the case where the MCG configuration in the first CHO configuration is executed).

[0198] In block 810, the UE performs a random access procedure on the target mobile node to access the target PCell. In other words, the UE accesses the target primary cell of the primary cell group upon detecting that at least one execution condition is satisfied. However, upon determining that at least one access condition is not satisfied upon detecting that at least one execution condition for conditional handover is satisfied, the UE delays accessing the target primary cell of the secondary cell group.

[0199] The UE may also send an indication to the target MN associated with the target PSCell, the indication indicating that at least one access condition of the target PSCell is not met when the at least one execution condition is met.

[0200] In block 811, after the random access procedure is completed, the target MN initiates an RRC reconfiguration procedure to the UE. The target MN may also configure the UE to report measurements related to the target PSCell (or candidate PSCell). For example, the measurements may include reference signal received power (RSRP) measurements and / or reference signal received quality (RSRQ) measurements.

[0201] In block 812, the target MN maintains or stores the SCG configuration of the target PSCell even if the UE performs a single connection.

[0202] The source MN may maintain the configuration based on a timer. In other words, a timer may be maintained on the network side and started when the UE is connected to the PCell (i.e., the random access procedure to the target MN is performed based on the CHO configuration). When the timer expires, the target MN releases the configuration. Furthermore, when the network triggers CPAC using the maintained configuration, the timer may be stopped (i.e., block 813).

[0203] Configurations maintained on the network side (i.e., the target MN) (e.g., SCG configurations) can be modified based on information received from the SN(s) (i.e., the SN modification procedure). The information received from the SN(s) can include, for example, network load information, and changes in network load can be a trigger for the modification. For example, the modification can represent the removal of a data radio bearer (DRB) from at least one maintained SCG configuration. This modification can be initiated by either the target MN or the SN.

[0204] In block 813, the target MN uses the maintained SCG configuration to configure CPAC for the target PSCell (e.g., PSCell-1 and PSCell-2) to the UE. In other words, the target MN determines the conditional cell addition change configuration for accessing the target primary cell of the secondary cell group based on the secondary cell group configuration.

[0205] In block 814, the target MN sends an RRC reconfiguration message to the UE to configure CPAC. In other words, the target MN sends a conditional cell addition change configuration to the UE. The UE may report measurements to the target MN before CPAC is configured.

[0206] In block 815, the UE sends an RRC reconfiguration complete message to the target MN to confirm receipt of the CPAC configuration and measurements for triggering CPAC.

[0207] In block 816, the UE evaluates the CPAC condition(s) based on the measurements related to the target PSCell. In other words, the UE may compare the measurements with the CPAC condition(s).

[0208] In block 817 , the UE determines that the CPAC condition(s) associated with the target PSCell are satisfied.

[0209] In block 818, the UE sends an RRC reconfiguration complete message to the target MN to confirm the configuration of the PSCell addition.

[0210] In block 819 , the UE performs a random access procedure to access the target PSCell.

[0211] In block 820, the target MN sends an SN modification confirmation (RRC reconfiguration complete) message to the target SN.

[0212] Figure 9 A signaling diagram according to an example embodiment is shown. In this example embodiment, the trigger is from the network side, rather than based on the UE. Therefore, the UE does not have to maintain the configuration because the configuration is maintained on the network side. In this example embodiment, the configuration can be provided to the UE as a PSCell Add Command in response to measurements received from the UE.

[0213] Initially, the UE may be configured with measurement configuration and report measurements of neighboring PSCells and possible PSCells.The source MN may determine that CHO preparation of the UE is necessary.

[0214] refer to Figure 9 In block 901, the source MN sends a CHO handover request to the target MN. In other words, the source MN indicates the CHO request to the target MN using measurements of the target PSCell.

[0215] In block 902, the target MN prepares target PSCells (eg, PSCell-1 and PSCell-2) by sending an SN add request to the target SN.

[0216] In block 903, the target SN sends an acknowledgement (ACK) of the SN add request to the target MN.

[0217] In block 904, each SCG configuration of the target PSCell may be configured in a separate CHO configuration at the target MN. For example, the target MN may determine a first CHO configuration of PCell-1 and PSCell-1, and a second CHO configuration of PCell-1 and PSCell-2. Here, PCell refers to the primary cell of the primary cell group, and PSCell refers to the primary cell of the secondary cell group.

[0218] In other words, the target MN can determine one or more configurations of conditional switching of the UE, wherein a given configuration among the one or more configurations includes at least: a primary cell group configuration of a target primary cell of a primary cell group, and a secondary cell group configuration of a target primary cell of a secondary cell group, and wherein the configuration is associated with at least one execution condition of the conditional switching, and at least one access condition of the target primary cell of the secondary cell group.

[0219] In block 905, the target MN sends an ACK for the handover request to the source MN. The target MN also sends one or more CHO configurations to the source MN, wherein the one or more configurations indicate delaying access to a target primary cell of the secondary cell group based on determining that at least one access condition is not satisfied when detecting that at least one execution condition of the conditional handover is satisfied.

[0220] In block 906, the source MN performs RRC reconfiguration to configure one or more CHO configurations and related conditions (i.e., at least one CHO execution condition and at least one PSCell access condition) for the UE. In other words, the UE receives the one or more CHO configurations and related conditions. The CHO configuration(s) may be sent along with a handover command for conditional handover.

[0221] In block 907, the UE sends an RRC reconfiguration complete message to the source MN to confirm the successful completion of the RRC reconfiguration.

[0222] In block 908, the UE determines that at least one CHO execution condition of the target PCell is satisfied, and the UE performs a PCell change to the target PCell. For example, the UE may perform an MCG configuration in the first CHO configuration in response to detecting that at least one CHO execution condition associated with the first CHO configuration is satisfied.

[0223] In block 909, the UE releases or deletes CHO configuration(s) other than the executed CHO configuration. For example, the UE may delete the second CHO configuration (in the case where the MCG configuration in the first CHO configuration is executed).

[0224] In block 910, the UE performs a random access procedure on the target mobile node to access the target PCell. In other words, the UE accesses the target primary cell of the primary cell group upon detecting that at least one execution condition is satisfied. However, upon determining that at least one access condition is not satisfied upon detecting that at least one execution condition for conditional handover is satisfied, the UE delays accessing the target primary cell of the secondary cell group.

[0225] The UE may also send an indication to the target MN, where the indication indicates that when the execution condition is met, at least one access condition of the target PSCell is not met.

[0226] After the random access procedure is completed, the target MN initiates an RRC reconfiguration procedure towards the UE in block 911. The target MN may also configure the UE to report measurements related to the target PSCell (candidate PSCell).

[0227] In block 912, the target MN maintains or stores the SCG configuration of the target PSCell even if the UE performs a single connection.

[0228] The source MN may maintain the configuration based on a timer. In other words, a timer may be maintained on the network side and started when the UE connects to the PCell (i.e., the random access procedure to the target MN is performed based on the CHO configuration). When the timer expires, the target MN releases the configuration. Furthermore, when the network triggers the addition of a PSCell using the maintained configuration, the timer may be stopped (i.e., block 914).

[0229] The configuration maintained at the network side (ie the target MN) may be modified using information received from the SN(s) (ie the SN modification procedure). Such modification may be initiated by the target MN or the SN.

[0230] In block 913, the UE sends a measurement report to the target MN to report measurements related to the target PSCell.

[0231] In block 914, if the measurement condition for adding any PSCell is satisfied based on the measurement report, the target MN triggers PSCell addition of the UE to the PSCell for which the measurement condition is satisfied using the maintained SCG configuration.

[0232] In block 915, the target MN sends an RRC reconfiguration message to the UE, where the RRC reconfiguration message includes a PSCell add command. The PSCell add command may also be referred to as a cell addition change configuration for the target primary cell (PSCell) of the secondary cell group. The difference between the PSCell add command and the CPAC configuration is that the PSCell add command does not involve any conditions, while the CPAC configuration involves one or more conditions to be met.

[0233] In block 916, the UE sends an RRC reconfiguration complete message to the target MN to confirm the successful completion of the RRC reconfiguration.

[0234] In block 917 , the UE performs a random access procedure based on the PSCell add command to access the target PSCell.

[0235] In block 918, the target MN sends an SN Modification Confirm (RRC Reconfiguration Complete) message to the target SN.

[0236] Figure 10 A flow chart according to an example embodiment of a method performed by an apparatus is illustrated. For example, the apparatus may be a user equipment, or include a user equipment, or be included in a user equipment. A user equipment may also be referred to as a subscriber unit, a mobile station, a remote terminal, an access terminal, a user terminal, a terminal device, or a user equipment (UE). The user equipment may correspond to Figure 1 One of the user equipments 100, 102, or corresponding to Figure 2 User equipment 203.

[0237] refer to Figure 10 In box 1001, one or more configurations of conditional switching are received, wherein the configuration in the one or more configurations includes at least: a primary cell group configuration of a target primary cell of a primary cell group, and a secondary cell group configuration of a target primary cell of a secondary cell group, and wherein the configuration is associated with at least one execution condition of the conditional switching and at least one access condition of the target primary cell of the secondary cell group.

[0238] In block 1002, upon detecting that at least one execution condition is satisfied, a target primary cell of the primary cell group is accessed. Here, accessing may refer to performing a random access procedure with the target primary cell. The random access procedure may also be referred to as a random access channel (RACH) procedure or a physical random access channel (PRACH) procedure.

[0239] In block 1003 , accessing a target primary cell of the secondary cell group is delayed based on determining that at least one access condition is not satisfied when detecting that at least one execution condition of conditional handover is satisfied.

[0240] Figure 11 A flow chart according to an example embodiment of a method performed by an apparatus is illustrated. For example, the apparatus may be a network element of a radio access network, or include a network element of a radio access network, or be included in a network element of a radio access network, such as the target master node mentioned above. The network element may correspond to Figure 1 Access node 104, or corresponding to Figure 2 The master node 201.

[0241] refer to Figure 11 In box 1101, one or more configurations of conditional switching of the user equipment are determined, wherein the configuration in the one or more configurations includes at least: a primary cell group configuration of a target primary cell of the primary cell group, and a secondary cell group configuration of a target primary cell of the secondary cell group, and wherein the configuration is associated with at least one execution condition of the conditional switching and at least one access condition of the target primary cell of the secondary cell group.

[0242] In block 1102 , one or more configurations are sent, wherein the one or more configurations indicate delaying access to a target primary cell of a secondary cell group based on determining that at least one access condition is not met upon detecting that at least one execution condition of conditional handover is met.

[0243] The above is with the help of Figure 3-Figure 11 The described boxes, related functions, and information exchanges (messages) are not performed in absolute chronological order, and some of them may be performed simultaneously or in an order different from the described order. Other functions may also be performed between them or within them, and other information may be sent, and / or other rules may be applied. Some boxes or parts of boxes or one or more pieces of information in a box may also be omitted or replaced with corresponding boxes or parts of boxes or one or more pieces of information.

[0244] As used herein, “at least one of: ” and “at least one of ” and similar expressions (where a list of two or more elements is connected by “and” or “or”) refer to at least any one element, or at least any two or more elements, or at least all elements.

[0245] Figure 12An example of an apparatus 1200 including components for performing one or more of the above-described exemplary embodiments is illustrated. For example, apparatus 1200 may be an apparatus such as a user device, or may be an apparatus including a user device, or may be an apparatus included in a user device. A user device may also be referred to as a subscriber unit, a mobile station, a remote terminal, an access terminal, a user terminal, a terminal device, or a user equipment (UE).

[0246] The device 1200 includes at least one processor 1210. The at least one processor 1210 interprets instructions (e.g., computer program instructions) and processes data. The at least one processor 1210 may include one or more programmable processors. The at least one processor 1210 may include programmable hardware with embedded firmware, and alternatively or additionally, may include one or more application-specific integrated circuits (ASICs).

[0247] At least one processor 1210 is coupled to at least one memory 1220. The at least one processor is configured to write data to the at least one memory 1220 and read data from the at least one memory 1220. The at least one memory 1220 may include one or more memory cells. The memory cells may be volatile or non-volatile. It should be noted that there may be one or more non-volatile memory cells and one or more volatile memory cells, or alternatively, there may be one or more non-volatile memory cells, or alternatively, there may be one or more volatile memory cells. Volatile memory may be, for example, random access memory (RAM), dynamic random access memory, or synchronous dynamic random access memory (SDRAM). Non-volatile memory may be, for example, read-only memory (ROM), programmable read-only memory (PROM), electrically erasable programmable read-only memory (EEPROM), flash memory, optical storage device, or magnetic storage device. In general, memory may be referred to as non-transitory computer-readable medium. The term "non-transitory" as used herein is a limitation on the medium itself (i.e., tangible, not a signal), rather than a limitation on the persistence of data storage (e.g., RAM vs. ROM). At least one memory 1220 stores computer-readable instructions that are executed by at least one processor 1210 to perform one or more of the above-described example embodiments. For example, non-volatile memory stores computer-readable instructions, and at least one processor 1210 uses volatile memory for temporary storage of data and / or instructions to execute the instructions. Computer-readable instructions may refer to computer program code.

[0248] The computer readable instructions may have been pre-stored in at least one memory 1220, or alternatively or additionally, they may be received by the device via an electromagnetic carrier signal and / or may be copied from a physical entity such as a computer program product. Execution of the computer readable instructions by at least one processor 1210 causes the device 1200 to perform one or more of the above-described example embodiments. That is, at least one processor and at least one memory storing instructions may provide means for providing or enabling the execution of any of the above-described methods and / or blocks.

[0249] In the context of this document, "memory" or "a computer-readable medium" or "computer-readable media" can be any one or more non-transitory media or components that can contain, store, communicate, propagate, or transport instructions for use by or in connection with an instruction execution system, apparatus, or device (such as a computer). The term "non-transitory" as used herein is a limitation on the medium itself (i.e., tangible, not a signal), not on the persistence of data storage (e.g., RAM vs. ROM).

[0250] The device 1200 may also include or be connected to an input unit 1230. The input unit 1230 may include one or more interfaces for receiving input. The one or more interfaces may include, for example, one or more temperature, motion, and / or orientation sensors, one or more cameras, one or more accelerometers, one or more microphones, one or more buttons, and / or one or more touch detection units. In addition, the input unit 1230 may include an interface to which external devices may be connected.

[0251] The device 1200 may also include an output unit 1240. The output unit may include or be connected to one or more displays capable of rendering visual content, such as a light-emitting diode (LED) display, a liquid crystal display (LCD), and / or a liquid crystal on silicon (LCoS) display. The output unit 1240 may also include one or more audio outputs. The one or more audio outputs may be, for example, speakers.

[0252] Apparatus 1200 also includes a connection unit 1250. Connection unit 1250 enables wireless connection to one or more external devices. Connection unit 1250 includes at least one transmitter and at least one receiver, which may be integrated into apparatus 1200 or to which apparatus 1200 may be connected. At least one transmitter includes at least one transmit antenna, and at least one receiver includes at least one receive antenna. Connection unit 1250 may include an integrated circuit or a set of integrated circuits that provide wireless communication capabilities for apparatus 1200. Alternatively, the wireless connection may be a hardwired application-specific integrated circuit (ASIC). Connection unit 1250 may also provide components for implementing at least some of the blocks of one or more of the example embodiments described above. Connection unit 1250 may include one or more components controlled by a corresponding control unit, such as a power amplifier, a digital front end (DFE), an analog-to-digital converter (ADC), a digital-to-analog converter (DAC), a frequency converter, a modulator (demodulator), and / or an encoder / decoder circuit system.

[0253] It should be noted that the apparatus 1200 may also include Figure 12 Various components are not shown in the figure. These various components can be hardware components and / or software components.

[0254] Figure 13 The diagram shows an example of an apparatus 1300 including components for performing one or more of the above-described exemplary embodiments. For example, the apparatus 1300 may be an apparatus such as a network element of a radio access network, or may be an apparatus including a network element of a radio access network, or may be an apparatus included in a network element of a radio access network. The network element may correspond to Figure 1 The access node 104 of the present invention may also be referred to as, for example, a network node, a master node, a target master node, a source master node, a radio access network (RAN) node, a next generation radio access network (NG-RAN) node, a NodeB, an eNB, a gNB, a base transceiver station (BTS), a base station, a NR base station, a 5G base station, an access node, an access point (AP), a relay node, a relay, an integrated access and backhaul (IAB) node, an IAB donor node, a distributed unit (DU), a central unit (CU), a baseband unit (BBU), a radio unit (RU), a radio head, a remote radio head (RRH), or a transmission and reception point (TRP).

[0255] The apparatus 1300 may include, for example, a circuit system or chipset suitable for implementing one or more of the above-described example embodiments. The apparatus 1300 may be an electronic device including one or more electronic circuit systems. The apparatus 1300 may include a communication control circuit system 1310 (such as at least one processor), and at least one memory 1320 storing instructions 1322 that, when executed by the at least one processor, cause the apparatus 1300 to perform one or more of the above-described example embodiments. For example, such instructions 1322 may include computer program code (software), wherein the at least one memory and the computer program code (software) are configured to, together with the at least one processor, cause the apparatus 1300 to perform one or more of the above-described example embodiments. The at least one processor and the at least one memory storing instructions may provide means for providing or causing the execution of any of the methods and / or blocks described above.

[0256] The processor is coupled to the memory 1320. The processor is configured to read data from the memory 1320 and write data to the memory 1320. The memory 1320 may include one or more memory cells. The memory cell may be volatile or non-volatile. It should be noted that there may be one or more non-volatile memory cells and one or more volatile memory cells, or alternatively, there may be one or more non-volatile memory cells, or alternatively, there may be one or more volatile memory cells. Volatile memory may be, for example, random access memory (RAM), dynamic random access memory (DRAM), or synchronous dynamic random access memory (SDRAM). Non-volatile memory may be, for example, read-only memory (ROM), programmable read-only memory (PROM), electrically erasable programmable read-only memory (EEPROM), flash memory, optical storage device, or magnetic storage device. In general, memory may be referred to as non-transitory computer-readable medium. The term "non-transitory" as used herein is a limitation on the medium itself (i.e., tangible, not a signal), rather than a limitation on the persistence of data storage (e.g., RAM and ROM). The memory 1320 stores computer-readable instructions executed by the processor. For example, non-volatile memory stores computer-readable instructions, and the processor uses volatile memory to temporarily store data and / or instructions to execute the instructions.

[0257] The computer readable instructions may have been pre-stored in the memory 1320, or alternatively or additionally, they may be received by the device via an electromagnetic carrier signal and / or may be copied from a physical entity (such as a computer program product). Execution of the computer readable instructions causes the device 1300 to perform one or more of the functions described above.

[0258] Memory 1320 may be implemented using any suitable data storage technology, such as semiconductor-based memory devices, flash memory, magnetic memory devices and systems, optical memory devices and systems, fixed memory, and / or removable memory. The memory may include a configuration database for storing configuration data. For example, the configuration database may store a list of current neighboring cells and, in some example embodiments, a frame structure used in detected neighboring cells.

[0259] The device 1300 may also include a communication interface 1330, which includes hardware and / or software for implementing a communication connection according to one or more communication protocols. The communication interface 1330 includes at least one transmitter (Tx) and at least one receiver (Rx), which can be integrated into the device 1300 or the device 1300 can be connected to them. The communication interface 1330 may provide components for performing some blocks of one or more example embodiments described above. The communication interface 1330 may include one or more components controlled by a corresponding control unit, such as a power amplifier, a digital front end (DFE), an analog-to-digital converter (ADC), a digital-to-analog converter (DAC), a frequency converter, a modulator (demodulator) and / or an encoder / decoder circuit system.

[0260] The communication interface 1330 provides the apparatus with radio communication capabilities for communicating in a cellular communication system. For example, the communication interface may provide a radio interface to one or more user equipment. The apparatus 1300 may also include another interface toward a core network (such as a network coordinator device or AMF) and / or an access node of the cellular communication system.

[0261] The apparatus 1300 may further include a scheduler 1340 configured to allocate radio resources. The scheduler 1340 may be configured together with the communication control circuit system 1310 or may be configured separately.

[0262] It should be noted that the apparatus 1300 may also include Figure 13 Various components are not shown in the figure. These various components can be hardware components and / or software components.

[0263] As used in this application, the term "circuitry" may refer to one or more or all of the following:

[0264] a) hardware circuit implementation only (such as implementation only in analog and / or digital circuitry); and

[0265] b) a combination of hardware circuitry and software such as (as applicable):

[0266] i) a combination of analog and / or digital hardware circuits and software / firmware, and

[0267] ii) hardware processor(s) with software (including any portion of digital signal processor(s), software and memory(s) that work together to enable the device (such as a mobile phone) to perform various functions); and

[0268] c) Hardware circuits and / or processor(s), such as microprocessor(s) or a portion of microprocessor(s), which require software (e.g., firmware)

[0269] To operate, but when the software is not needed to operate, the software may not exist.

[0270] This definition of circuitry applies to all uses of the term in this application, including in any claims. As a further example, as used in this application, the term circuitry also covers merely a hardware circuit or processor (or multiple processors) or a portion of a hardware circuit or process and its accompanying software and / or firmware implementation. For example, 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 networking device, if applicable to the particular claim element.

[0271] The techniques and methods described herein can be implemented in various ways. For example, these techniques can be implemented in hardware (one or more devices), firmware (one or more devices), software (one or more modules), or a combination thereof. For hardware implementation, the (multiple) devices of the example embodiments can be implemented in one or more application-specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), field programmable gate arrays (FPGAs), graphics processing units (GPUs), processors, controllers, microcontrollers, microprocessors, other electronic units designed to perform the functions described herein, or a combination thereof. For firmware or software, implementation can be achieved by modules (e.g., processes, functions, etc.) of at least one chipset that performs the functions described herein. The software code can be stored in a memory unit and executed by a processor. The memory unit can be implemented within the processor or externally. In the latter case, as is known in the art, the memory unit can be communicatively coupled to the processor in various ways. In addition, those skilled in the art will understand that the components of the systems described herein can be rearranged and / or supplemented by additional components to facilitate the implementation of the various aspects described, etc., and they are not limited to the precise configurations set forth in the given figures.

[0272] It is clear to those skilled in the art that, as technology advances, the inventive concept can be implemented in various ways. The embodiments are not limited to the above-described example embodiments, but may vary within the scope of the claims. Therefore, all words and expressions should be interpreted broadly, and they are intended to illustrate rather than limit the example embodiments.

Claims

1. An apparatus comprising at least one processor and at least one memory storing instructions, wherein when the instructions are executed by the at least one processor, the apparatus at least: Receiving one or more configurations of conditional switching, wherein a configuration in the one or more configurations includes at least: a primary cell group configuration of a target primary cell of a primary cell group, and a secondary cell group configuration of a target primary cell of a secondary cell group, wherein the configuration is associated with at least one execution condition of the conditional switching and at least one access condition of the target primary cell of the secondary cell group; When detecting that the at least one execution condition is met, accessing the target primary cell of the primary cell group; as well as Based on determining that the at least one access condition is not satisfied when detecting that the at least one execution condition of the conditional handover is satisfied, accessing the target primary cell of the secondary cell group is delayed.

2. The apparatus according to claim 1, further configured to: storing at least the secondary cell group configuration; Upon detecting that the at least one execution condition of the conditional switching is satisfied, starting a timer, wherein the timer is configured to expire after a time period; and When it is detected that the at least one access condition is satisfied before the timer expires, access is made to the target primary cell of the secondary cell group based on the stored secondary cell group configuration.

3. The apparatus according to claim 1, further configured to: upon detecting that the at least one execution condition of the conditional switching is satisfied, starting a timer, wherein the timer is configured to expire after a time period; determining that the at least one access condition is not satisfied within the time period; as well as An indication is sent to a target primary node associated with the target primary cell, the indication indicating that the at least one access condition is not satisfied within the time period.

4. The apparatus according to claim 1, further configured to: Upon detecting that the at least one execution condition of the conditional switching is satisfied, starting a timer, wherein the timer is configured to expire after a time period; and Based on detecting that the at least one access condition is satisfied before the timer expires, applying the secondary cell group configuration.

5. The apparatus according to claim 1, further configured to: Upon detecting that the at least one execution condition of the conditional switching is satisfied, starting a timer, wherein the timer is configured to expire after a time period; and Based on detecting that the at least one access condition is satisfied within the time period, the primary cell group configuration and the secondary cell group configuration are applied.

6. The apparatus according to claim 1, further configured to: storing at least the secondary cell group configuration; Upon detecting that the at least one execution condition of the conditional switching is satisfied, starting a timer, wherein the timer is configured to expire after a time period; and When it is determined that the at least one access condition is not satisfied within the time period, at least the secondary cell group configuration is deleted.

7. The apparatus according to claim 1, further configured to: storing at least the secondary cell group configuration; and When an indication to release at least the secondary cell group configuration is received, at least the secondary cell group configuration is deleted.

8. The apparatus according to claim 1, further configured to: sending an indication to a target primary node associated with the target primary cell, the indication indicating that: when the at least one execution condition is satisfied, the at least one access condition is not satisfied; receiving, from the target primary node, a configuration for reporting measurements related to the target primary cell of the secondary cell group; reporting the measurement related to the target primary cell of the secondary cell group to the target primary node; receiving, based on the report, from the target primary node, a cell addition change configuration of the target primary cell of the secondary cell group; as well as Based on the cell addition change configuration, access the target primary cell of the secondary cell group.

9. An apparatus comprising at least one processor and at least one memory storing instructions, wherein the instructions, when executed by the at least one processor, cause the apparatus to at least: Determine one or more configurations of conditional switching of a user equipment, wherein a configuration in the one or more configurations includes at least: a primary cell group configuration of a target primary cell of a primary cell group, and a secondary cell group configuration of a target primary cell of a secondary cell group, wherein the configuration is associated with at least one execution condition of the conditional switching and at least one access condition of the target primary cell of the secondary cell group; The one or more configurations are sent, wherein the one or more configurations indicate: based on determining that the at least one access condition is not met when detecting that the at least one execution condition of the conditional switching is met, delaying access to the target primary cell of the secondary cell group.

10. The apparatus according to claim 9, further configured to: receiving an indication from the user equipment, the indication indicating that: when the at least one execution condition is satisfied, the at least one access condition is not satisfied; Based on the secondary cell group configuration, determining a conditional cell addition change configuration of the target primary cell for accessing the secondary cell group; and The conditional cell addition change configuration is sent to the user equipment.

11. The apparatus according to claim 9, further configured to: receiving an indication from the user equipment, the indication indicating that: when the at least one execution condition is satisfied, the at least one access condition is not satisfied; Sending, to the user equipment, a configuration for reporting measurements related to the target primary cell of the secondary cell group; receiving, from the user equipment, a report including the measurements related to the target primary cell of the secondary cell group; as well as Based on the report, a cell addition change configuration of the target primary cell for accessing the secondary cell group is sent to the user equipment.

12. The device according to any one of claims 9 to 11, further configured to: storing at least the secondary cell group configuration; upon detecting that the user equipment is connected to the target primary cell, starting a timer, wherein the timer is configured to expire after a time period; and When the timer expires, at least the secondary cell group configuration is released.

13. The device according to any one of claims 9 to 12, further configured to: The secondary cell group configuration is modified based on information received from a secondary node associated with the target primary cell of the secondary cell group.

14. A method comprising: Receiving one or more configurations of conditional handover, wherein the configurations in the one or more configurations include at least: a primary cell group configuration of a target primary cell of a primary cell group, and a secondary cell group configuration of a target primary cell of a secondary cell group, and wherein the configurations are associated with at least one execution condition of the conditional handover and at least one access condition of the target primary cell of the secondary cell group; When it is detected that the at least one execution condition is satisfied, accessing the target primary cell of the primary cell group; and Based on determining that the at least one access condition is not satisfied when detecting that the at least one execution condition of the conditional handover is satisfied, accessing the target primary cell of the secondary cell group is delayed.

15. A non-transitory computer readable medium comprising program instructions, which when executed by an apparatus causes the apparatus to at least perform: Receiving one or more configurations of conditional switching, wherein a configuration in the one or more configurations includes at least: a primary cell group configuration of a target primary cell of a primary cell group, and a secondary cell group configuration of a target primary cell of a secondary cell group, wherein the configuration is associated with at least one execution condition of the conditional switching and at least one access condition of the target primary cell of the secondary cell group; When detecting that the at least one execution condition is met, accessing the target primary cell of the primary cell group; as well as Based on determining that the at least one access condition is not satisfied when detecting that the at least one execution condition of the conditional handover is satisfied, accessing the target primary cell of the secondary cell group is delayed.

Images