COMMUNICATION DEVICE, BASE STATION, METHOD, AND INTEGRATED CIRCUIT INVOLVED IN CELL MOBILITY PROCEDURE

Abstract

The present disclosure relates to a communications device comprising: a receiver receiving a plurality of cell configurations from a source base station, each cell configuration including cell configuration parameters for performing a conditional cell mobility procedure for a respective candidate target cell and including an execution condition for when to perform the conditional cell mobility procedure; the plurality of cell configurations including a first subset of cell configurations to be evaluated by the communications device when connected to the source base station; and the plurality of cell configurations including a second subset of cell configurations to be evaluated by the communications device when connected to a first candidate target cell of the plurality of candidate target cells, the first candidate target cell being different from the source cell of the source base station. Circuitry of the communications device evaluates the execution condition for only the first subset of cell configurations.

Description

[Technical Field]

[0001] The present disclosure is directed to methods, apparatus, and articles in communication systems, such as 3GPP® communication systems. [Background technology]

[0002] Currently, the 3rd Generation Partnership Project (3GPP) is working on technical specifications for a new radio access technology—5G New Radio (NR), also referred to as fifth generation (5G) or NR, which are used interchangeably herein.

[0003] One objective is to provide a single technical framework that addresses all usage scenarios, requirements, and deployment scenarios (see, for example, Section 6 of 3GPP TR 38.913, e.g., v16.0.0 or v17.0.0) including at least enhanced mobile broadband (eMBB), ultra-reliable low-latency communications (URLLC), and massive machine-type communications (mMTC). For example, deployment scenarios for eMBB may include indoor hotspots, dense urban areas, suburban areas, and urban macro-high-speed environments. Deployment scenarios for URLLC may include industrial control systems, mobile health management (remote monitoring, remote diagnosis, and remote treatment), real-time control of vehicles, and wide-area monitoring and control systems for smart grids. Deployment scenarios for mMTC may include scenarios using a large number of devices where data transmission latency is minimal, such as smart wearables and sensor networks. eMBB and URLLC services are similar in that they both require very high bandwidth, but URLLC services differ in that they preferably require very low latency.

[0004] A second goal is to achieve forward compatibility, which facilitates the introduction of entirely new system designs and / or new features. Summary of the Invention [Problem to be solved by the invention]

[0005] One non-limiting, exemplary embodiment facilitates providing a procedure for a UE to perform an improved cell mobility procedure. [Means for solving the problem]

[0006] In one embodiment, the technology disclosed herein features a user equipment (UE) including: a receiver unit of the UE receives, from a source base station, a plurality of cell configurations for a plurality of candidate target cells; each cell configuration includes cell configuration parameters for performing a conditional cell mobility procedure for each candidate target cell and an execution condition for when to perform the conditional cell mobility procedure for each candidate target cell; the plurality of cell configurations includes a first subset of cell configurations that are evaluated by the UE when the UE is connected to the source base station; and the plurality of cell configurations includes a second subset of cell configurations that are evaluated by the UE when connected to a first candidate target cell of the plurality of candidate target cells, the first candidate target cell being different from the source cell of the source base station. A circuit in the UE evaluates the execution condition for only the first subset of cell configurations. The circuit performs the conditional cell mobility procedure for the first candidate target cell based on the cell configuration parameters of the first candidate target cell if the evaluated execution condition for the cell configuration of the first subset of cell configurations for the first candidate target cell is satisfied.

[0007] It should be noted that the general or specific embodiments may be implemented as a system, a method, an integrated circuit, a computer program, a storage medium, or any combination thereof. For example, the integrated circuit may control processing of a UE or a base station.

[0008] Further benefits and advantages of the disclosed embodiments and various implementations will become apparent from the specification and drawings. Such benefits and / or advantages may be provided by some of the embodiments and features described in the specification and drawings, respectively, but not necessarily all of them may be provided to obtain one or more identical features.

[0009] The following exemplary embodiments are described in more detail with reference to the accompanying drawings. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 illustrates an example architecture of a 3GPP NR system to which the improved procedures of the present disclosure can be applied. [Figure 2] 1 is a schematic diagram illustrating the functional division between the NG Radio Access Network (NG-RAN) and the 5G Core Network (5GC), to which the improved procedures of the present disclosure may be applied; [Figure 3] 1 is a sequence diagram of a Radio Resource Control (RRC) connection setup / reconfiguration procedure to which the improved procedures of the present disclosure may be applied. [Figure 4] FIG. 1 is a schematic diagram illustrating eMBB, mMTC, and URLLC usage scenarios in which the improved procedures of the present disclosure may be applied. [Figure 5] Block diagram illustrating an example 3GPP NR system architecture for a non-roaming scenario [Figure 6] Diagram outlining the different cell types in dual connectivity [Figure 7] Signaling diagram for handover involving UE, source gNB, and target gNB [Figure 8] Diagram showing an example of a conditional handover involving a UE, a source gNB, and a target gNB [Figure 9] FIG. 1 illustrates another exemplary conditional handover. [Figure 10]FIG. 1 illustrates another exemplary conditional handover. [Figure 11] Signaling diagram for conditional PSCell change procedure [Figure 12] Signaling diagram for conditional PSCell addition procedure [Figure 13] FIG. 1 shows an exemplary simplified structure of a UE and a gNB. [Figure 14] FIG. 1 is a diagram illustrating the structure of a UE according to an example of implementing the improved mobility procedure of the first solution; [Figure 15] FIG. 1 shows a flow diagram of UE behavior according to an example implementation of the improved mobility procedure of the first solution; [Figure 16] FIG. 1 is a diagram illustrating the structure of a source base station according to an example of implementing the improved mobility procedure of the first solution; [Figure 17] 1 is a flow diagram of the behavior of a source base station according to an example of an implementation of the improved mobility procedure of the first solution; [Figure 18] FIG. 1 illustrates the structure of a target base station according to an example of implementing the improved mobility procedures of the first and second solutions. [Figure 19] 1 is a flow diagram of the behavior of a target base station according to an example implementation of the improved mobility procedure of the first and second solutions. [Figure 20] FIG. 1 shows an example of signaling exchange between a UE, a source gNB and a target gNB in one embodiment of an improved mobility procedure of the first solution, in particular an improved CHO procedure. [Figure 21] FIG. 1 illustrates an example of signaling exchange between a UE, a source gNB, and a target gNB for preparing CHO configuration and CHO pre-configuration according to an improved CHO procedure according to a first solution; [Figure 22] FIG. 1 illustrates an example of signaling exchange between a UE, a source gNB, and a target gNB in an example implementation of the improved CPC procedure of the first solution. [Figure 23] FIG. 1 illustrates an example of signaling exchange between a UE, a source gNB, and a target gNB in an example implementation of the improved CPA procedure of the first solution. [Figure 24] FIG. 10 is a diagram showing the structure of a UE according to an example of implementing the improved mobility procedure of the second solution; [Figure 25] 1 is a flow diagram of a UE's behavior according to an example of an implementation of the improved mobility procedure of the second solution; [Figure 26] FIG. 10 is a diagram illustrating the structure of a source base station according to an example of implementing the improved mobility procedure of the second solution. [Figure 27] 1 is a flow diagram of the behavior of a source base station according to an example of implementation of the improved mobility procedure of the second solution; [Figure 28] FIG. 10 illustrates an example of signaling exchange between a UE, a source gNB, and a target gNB in an example implementation of the improved CPA procedure of the second solution. DETAILED DESCRIPTION OF THE INVENTION

[0011] <5G NR system architecture and protocol stack> 3GPP is working on the next release of fifth-generation cellular technology (known simply as "5G"), which includes the development of a new radio access technology (NR) that will operate in frequencies up to 100 GHz. The first version of the 5G standard was completed at the end of 2017, allowing for the testing and commercial deployment of smartphones compliant with the 5G NR standard.

[0012] In particular, the overall system architecture assumes a Next Generation Radio Access Network (NG-RAN) with gNodeBs (gNBs), which terminate NG radio access user plane (SDAP / PDCP / RLC / MAC / PHY) protocols and control plane (Radio Resource Control (RRC)) protocols toward UEs. The gNBs are interconnected with each other via an Xn interface. The gNBs are also connected to 5GC via a Next Generation (NG) interface, more specifically to the Access and Mobility Management Function (AMF) (e.g., a specific core entity running AMF) via an NG-C interface and to the User Plane Function (UPF) (e.g., a specific core entity running UPF) via an NG-U interface. The NG-RAN architecture is shown in Figure 1 (see, e.g., Section 4 of 3GPP TS 38.300, e.g., v16.8.0).

[0013] The user plane protocol stack in NR (see, for example, Section 4.4.1 of 3GPP TS 38.300) includes the PDCP (Packet Data Convergence Protocol) sublayer, the RLC (Radio Link Control) sublayer, and the MAC (Medium Access Control) sublayer, which are terminated in the gNB on the network side. In addition, a new access stratum (AS) sublayer (SDAP, Service Data Adaptation Protocol) is introduced above PDCP (see, for example, Section 6.5 of TS 38.300). A control plane protocol stack is also defined in NR (see, for example, Section 4.4.2 of TS 38.300). An overview of Layer 2 functionality is given in TS 38.300, clause 6. RRC layer functionality is given in TS 38.300, clause 7.

[0014] For example, the Medium-Access-Control (MAC) layer handles scheduling and scheduling-related functions, including multiplexing logical channels and handling various numerologies.

[0015] The physical layer (PHY) is responsible for, for example, coding, PHY HARQ processing, modulation, multi-antenna processing, and mapping of signals to appropriate physical time-frequency resources. The physical layer also handles mapping of transport channels to physical channels. The physical layer provides services to the MAC layer in the form of transport channels. A physical channel corresponds to a set of time-frequency resources used for transmitting a specific transport channel, and each transport channel is mapped to a corresponding physical channel. For example, physical channels are the PRACH (Physical Random Access Channel), PUSCH (Physical Uplink Shared Channel), and PUCCH (Physical Uplink Control Channel) for the uplink, and the PDSCH (Physical Downlink Shared Channel), PDCCH (Physical Downlink Control Channel), and PBCH (Physical Broadcast Channel) for the downlink.

[0016] NR use cases / deployment scenarios include enhanced mobile broadband (eMBB), ultra-reliable and low-latency communications (URLLC), and / or massive machine-type communications (mMTC), which have diverse requirements for data rates, latency, and coverage. For example, eMBB is expected to support peak data rates (20 Gbps downlink and 10 Gbps uplink) and user-perceived data rates on the order of three times those offered by IMT-Advanced. In contrast, URLLC has more stringent requirements, including extremely low latency (user plane latency of 0.5 ms for UL and DL, respectively) and high reliability (1-10 Mbps within 1 ms). -5) and mMTC requires high connection density (1 km in urban environments). 2 1,000,000 devices per second), wide coverage in harsh environments, and extremely long battery life (15 years) to lower device costs may preferably be required.

[0017] Therefore, an OFDM numerology (e.g., subcarrier spacing, OFDM symbol length, cyclic prefix (CP) length, number of symbols per scheduling interval) suitable for one use case may not work well for another use case. For example, low-latency services may preferably require a shorter symbol length (and therefore a larger subcarrier spacing) and / or fewer symbols per scheduling interval (also referred to as TTI) than mMTC services. Furthermore, deployment scenarios with large channel delay spreads may preferably require a longer CP length than scenarios with small delay spreads. To maintain a similar CP overhead, the subcarrier spacing should be optimized depending on the delay spread. In NR, more than one value of subcarrier spacing may be supported. Therefore, subcarrier spacings of 15 kHz, 30 kHz, 60 kHz, ... are currently being considered. The symbol length T u and the subcarrier spacing Δf is given by the formula (Δf=1 / T u ) As in LTE systems, the term "resource element" can be used to denote the smallest resource unit consisting of one subcarrier for the length of one OFDM / SC-FDMA symbol.

[0018] In the new radio system 5G-NR, a resource grid of subcarriers and OFDM symbols is defined for each numerology and carrier in the uplink and downlink, respectively. Each element in the resource grid is called a resource element and is identified based on its frequency index in the frequency domain and its symbol position in the time domain (see, for example, Section 4 of 3GPP TS 38.211 v17.1.0). For example, downlink and uplink transmissions are configured as frames with a time length of 10 ms. Each frame consists of 10 subframes, each with a time length of 1 ms. In a 5G NR implementation, the number of consecutive OFDM symbols per subframe depends on the subcarrier spacing setting. For example, with a subcarrier spacing of 15 kHz, a subframe has 14 OFDM symbols (similar to an LTE-compliant implementation, assuming a normal cyclic prefix). On the other hand, with a subcarrier spacing of 30 kHz, a subframe has two slots, each with 14 OFDM symbols.

[0019] <Functional separation between NG-RAN and 5GC in 5G NR> Figure 2 shows the division of functions between NG-RAN and 5GC. The logical nodes of NG-RAN are gNB or ng-eNB (next generation eNB). The logical nodes of 5GC are AMF, UPF, and SMF.

[0020] In particular, the gNB and ng-eNB handle the following key functions: Radio Resource Management functions, such as Radio Bearer Control, Radio Admission Control, Connection Mobility Control, and dynamic resource allocation (scheduling) to UEs in both uplink and downlink directions. - IP header compression, encryption, and integrity protection of data - AMF selection at UE attach time when routing to the AMF cannot be determined from information provided by the UE - Routing of user plane data to the UPF - Routing of control plane information to AMF - Establishing and releasing connections - scheduling and sending of paging messages - scheduling and transmission of system broadcast information (sent from AMF or OAM) - Configuring measurements and measurement reporting for mobility and scheduling - Transport-level packet marking in the uplink - Session Management - Network slicing support - QoS flow management and mapping to data radio bearers - Support for UEs in RRC_INACTIVE state - Non-access stratum (NAS) message delivery function - Radio Access Network Sharing - Dual Connectivity - Close interworking between NR and E-UTRA

[0021] The Access and Mobility Management Function (AMF) handles the following main functions: - Termination of Non-Access Stratum (NAS) signaling - NAS signaling security - Access Stratum (AS) security control - Core Network (CN) inter-node signaling for mobility between 3GPP access networks - Reachability for idle mode UEs (including control and execution of paging retransmissions) - Registration Area Management - Support for intra-system and inter-system mobility - Access Authentication - Access authentication, including roaming rights checks - Mobility management controls (subscriptions and policies) - Network slicing support - Selection of Session Management Function (SMF)

[0022] Furthermore, the User Plane Function (UPF) handles the following main functions: - Anchor points for intra-RAT / inter-RAT mobility (when applicable) - External PDU session points for interconnection with data networks - Packet routing and forwarding - User plane portion of packet inspection and policy rule enforcement - Traffic Usage Report - Uplink classifier to support routing of traffic flows to the data network - Branching points to support multi-homed PDU sessions - User plane QoS processing (e.g., packet filtering, gating, UL / DL rate enforcement) - Verification of uplink traffic (mapping from SDF to QoS flow) - Downlink packet buffering and downlink data notification triggering

[0023] Finally, the Session Management Function (SMF) handles the following major functions: - Session Management - UE IP address allocation and management - Selection and control of the UP function - Configuration of traffic steering in the user plane function (UPF) for routing traffic to the correct destination - Policy enforcement and QoS control part - Downlink data notification

[0024] <Procedures for establishment and reconfiguration of RRC connection> Figure 3 shows the interactions among the UE, gNB, and AMF (5GC entity) in the NAS part when the UE transitions from RRC_IDLE to RRC_CONNECTED (see TS 38.300).

[0025] RRC is the upper layer signaling (protocol) used for the configuration of the UE and gNB. In particular, in this transition, the AMF creates UE context data (including, for example, PDU session context, security keys, UE radio capabilities, UE security capabilities, etc.) and sends it to the gNB via an INITIAL CONTEXT SETUP REQUEST (Initial Context Setup Request). Next, the gNB activates the AS security with the UE, which is executed by the gNB sending a SecurityModeCommand message to the UE and the UE responding to the gNB with a SecurityModeComplete message. Thereafter, the gNB performs reconfiguration to establish signaling radio bearer 2 (SRB2) and data radio bearer (DRB: Data Radio Bearer), which is by the gNB sending an RRCReconfiguration message to the UE and receiving RRCReconfigurationComplete from the UE in response. In the case of a signaling-only connection, since SRB2 and DRB are not established, these steps related to RRCReconfiguration are skipped. Finally, the gNB notifies the AMF via an INITIAL CONTEXT SETUP RESPONSE (Initial Context Setup Response) that the establishment procedure has completed.

[0026]

[0009] Accordingly, the present disclosure provides a fifth generation core (5GC) entity (e.g., AMF, SMF, etc.) having, in operation, circuitry for establishing a next generation (NG) connection with a gNodeB such that a signaling radio bearer is established between the gNodeB and a user equipment (UE), and a transmitter for, in operation, transmitting an initial context setup message to the gNodeB via the NG connection. In particular, the gNodeB transmits radio resource control (RRC) signaling including a resource allocation configuration information element (IE) to the UE via the signaling radio bearer. The UE then performs uplink transmission or downlink reception based on the resource allocation configuration.

[0027] <IMT usage scenarios after 2020> Figure 4 illustrates some of the use cases for 5G NR. The 3GPP NR (3rd Generation Partnership Project New Radio) project considers three use cases envisioned for IMT-2020 to support a wide variety of services and applications. Phase 1 specifications for enhanced mobile broadband (eMBB) have been finalized. Current and future work includes standardization for ultra-reliable and low-latency communications (URLLC) and massive machine-type communications (mMTC), in addition to further extending eMBB support. Figure 4 illustrates some example IMT usage scenarios envisioned for 2020 and beyond (see, for example, Figure 2 in ITU-R M.20183).

[0028] URLLC use cases have stringent requirements for capabilities such as throughput, latency, and availability, and are envisioned as one of the enablers for future vertical applications, such as wireless control of industrial manufacturing or production processes, remote medical surgery, power distribution automation in smart grids, and transportation safety. URLLC's ultra-high reliability is supported by identifying technologies to meet the requirements set by 3GPP TR 38.913, version 16.0.0. For NR URLLC in Release 15, key requirements include a user plane target latency of 0.5 ms for the uplink (UL) and 0.5 ms for the downlink (DL). Typical URLLC requirements for a single packet transmission are a block error rate (BLER) of 1E-5 for a 32-byte packet size with a 1-ms user plane latency.

[0029] From a physical layer perspective, there are several possible ways to improve reliability. The current scope for improving reliability includes defining a separate CQI table for URLLC, a more compact Downlink Control Information (DCI) format, PDCCH repetition, etc. However, as NR becomes more stable and more developed (a key requirement for NR URLLC), the scope for achieving ultra-high reliability may expand. Specific use cases for NR URLLC in Release 15 include augmented reality / virtual reality (AR / VR), e-health, e-safety, and mission-critical applications.

[0030] Furthermore, technology enhancements targeted at NR URLLC target latency improvement and reliability enhancement. Technology enhancements for latency improvement include configurable numerology, non-slot-based scheduling with flexible mapping, grant-free (configured grant) uplink, slot-level repetition of data channels, and downlink preemption. Preemption means that a transmission for which resources have already been allocated is aborted and the already allocated resources are used for another transmission requested later with smaller latency / higher priority requirements. Thus, an already granted transmission is preempted by a later transmission. Preemption applies regardless of the specific service type. For example, a transmission of service type A (URLLC) can be preempted by a transmission of service type B (e.g., eMBB). Technology enhancements for reliability improvement include dedicated CQI / MCS tables for a target BLER of 1E-5.

[0031] The mMTC (Massive Machine Type Communication) use case is characterized by a very large number of connected devices transmitting relatively small amounts of data that are generally latency sensitive. The devices need to be low cost and have extremely long battery life. From an NR perspective, utilizing very narrow bandwidth portions is one possible solution to achieve power savings from the UE perspective, enabling long battery life.

[0032] As mentioned above, it is expected that the range of reliability in NR will expand. One key requirement for all cases, especially for URLLC and mMTC, is high or ultra-high reliability. Several mechanisms can be considered to improve reliability from a radio perspective and a network perspective. In general, there are several key areas that can help improve reliability. These areas include compact control channel information, data channel / control channel repetition, and diversity related to the frequency, time, and / or spatial domains. These areas are generally applicable to reliability, regardless of the specific communication scenario.

[0033] Additional use cases with more stringent requirements are envisioned for NR URLLC, such as factory automation, transportation, and power distribution. The more stringent requirements include higher reliability (up to 10 times faster), depending on the use case. -6 level), higher availability, packet size up to 256 bytes, time synchronization on the order of a few microseconds (values range from 1 to a few microseconds depending on the frequency range), and short latency on the order of 0.5 to 1 ms (target latency for the user plane in particular is 0.5 ms).

[0034] Furthermore, for NR URLLC, several technical enhancements are possible from the perspective of the physical layer. In particular, enhancements related to PDCCH (Physical Downlink Control Channel) include compact DCI, repetition of PDCCH, and increased PDCCH monitoring. Also, enhancements related to UCI (Uplink Control Information) include enhancements of HARQ (Hybrid Automatic Repeat Request) and CSI feedback. In addition, enhancements of PUSCH related to mini-slot level hopping and retransmission / repetition have also been recognized. The term "mini-slot" means a transmission time interval (TTI: Transmission Time Interval) that contains a smaller number of symbols than a slot (a slot contains, for example, 14 symbols).

[0035] <QoS Control> The 5G QoS (Quality of Service) model is based on QoS flows and supports both QoS flows that require a guaranteed flow bit rate (GBR QoS flows) and QoS flows that do not require a guaranteed flow bit rate (non-GBR QoS flows). Therefore, at the NAS level, the QoS flow is the finest granularity for QoS differentiation in a PDU session. A QoS flow is identified within a PDU session by a QoS flow ID (QFI) that is transmitted within the encapsulation header through the NG-U interface.

[0036] The 5GC establishes one or more PDU sessions for each UE. The NG-RAN establishes at least one Data Radio Bearer (DRB) for each UE along with the PDU session, and can then configure additional DRBs for the QoS flows of that PDU session (as determined by the NG-RAN, e.g., as described above with reference to Figure 3). The NG-RAN maps packets belonging to different PDU sessions to different DRBs. NAS-level packet filters in the UE and 5GC associate UL and DL packets with QoS flows, and AS-level mapping rules in the UE and NG-RAN associate UL and DL QoS flows with DRBs.

[0037] Figure 5 illustrates the 5G NR non-roaming reference architecture (see, for example, Section 4.23 of v16.9.0 or v17.4.0 of 3GPP TS 23.501). Application Functions (AFs) (e.g., external application servers handling 5G services, as exemplarily illustrated in Figure 4) interact with the 3GPP Core Network to provide services. For example, they may support application influence on traffic routing, access Network Exposure Functions (NEFs), or interact with a policy framework (see Policy Control Function (PCF)) for policy control (e.g., QoS control). Based on the operator's deployment, Application Functions (AFs) deemed trusted by the operator may be allowed to interact directly with the associated Network Functions. Application Functions (AFs) not authorized by the operator to directly access Network Functions interact with the associated Network Functions using an external exposure framework via the NEF.

[0038] Figure 5 shows further functional units of the 5G architecture: Network Slice Selection Function (NSSF), Network Repository Function (NRF), Unified Data Management (UDM), Authentication Server Function (AUSF), Access and Mobility Management Function (AMF), Session Management Function (SMF), and Data Network (DN) (e.g., operator services, internet access, or third-party services). All or part of the core network functions and application services may be located and run in a cloud computing environment.

[0039] Therefore, the present disclosure provides an application server (e.g., an AF in a 5G architecture) having: a transmitter that, when operated, sends a request including QoS requirements for at least one of a URLLC service, an eMMB service, and an mMTC service to at least one of 5GC functions (e.g., an NEF, an AMF, an SMF, a PCF, an UPF, etc.) to establish a PDU session including a radio bearer between a gNodeB and a UE in accordance with the QoS requirements; and a circuit that, when operated, performs the service using the established PDU session.

[0040] <5G NR cell types> In 5G NR, there are several types of cells: PCell, SCell, PSCell, and SpCell.

[0041] The PCell is a primary cell that may be used to initiate initial access.

[0042] An SCell is a secondary cell. One or more SCells can be configured for a UE in connected mode. An SCell can be enabled or disabled depending on, for example, traffic.

[0043] PSCell is closely related to Dual Connectivity (DC). E-UTRAN supports Dual Connectivity (DC) operation, where a Multiple-Rx / Tx UE in RRC_CONNECTED can be configured to utilize radio resources provided by two different schedulers located in two nodes (master node, secondary node) connected by a non-ideal backhaul via the X2 interface. The master node provides the control plane connection to the core network. The secondary node does not have a control plane connection with the core network but provides additional resources to the UE in case of MR-DC.

[0044] In dual connectivity, there are two cell groups: a Master Cell Group (MCG) and a Secondary Cell Group (SCG). The MCG may have one PCell and one or more SCells. The SCG may have one PSCell and one or more SCells. The UE performs initial access in the SCG via the PSCell. Since most signaling messages are transmitted only via the PCell and PSCell, for ease of explanation, 3GPP defines the concept of a Special cell (SpCell), which is understood as SpCell = Pcell + PSCell.

[0045] Figure 6 provides an overview of the different cell types in dual connectivity. There is also the possibility of Multi-Radio Dual Connectivity (MR-DC), where the Master RAN Node acts as the control entity utilizing the secondary RAN for additional data capacity. MR-DC configurations include E-UTRA and NR dual connectivity (EN-DC: E-UTRA - NR Dual Connectivity), NR dual connectivity (NR-DC: New Radio Dual Connectivity), NG-RAN and E-UTRA dual connectivity (NGEN-DC: NG-RAN - E-UTRA Dual Connectivity), and NR and E-UTRA dual connectivity (NE-DC: NR - E-UTRA Dual Connectivity).

[0046] TS 37.340 v17.1.0 defines multi-radio dual connectivity in clause 4. As indicated in TS 38.300 v17.1.0 clause 4.5, conditional PSCell addition (CPA) and conditional PSCell change (CPC) are defined in TS 37.340 and are further described below.

[0047] <Handover procedure> An exemplary simplified handover is shown in Figure 7 and briefly described below. Handover of a UE involves a source base station making a decision whether to handover the UE from a source / serving gNB to a neighboring / target gNB (target radio cell). This decision is typically made by the source gNB based on measurement results from the UE. The measurement results may be carried in one or more measurement reports, for example, as shown in the measurement report of Figure 7. The measurement reports are sent by the UE to assist the source cell in the handover procedure.

[0048] Then, a handover is prepared (preparation phase) between the two base stations involved, i.e., a source base station (herein, source gNB, which may be used interchangeably with source cell) and a target base station (herein, target gNB, which may be used interchangeably with target cell). The source gNB sends a handover request message to the target base station, and the target base station may respond with a handover request acknowledgement message to perform the preparation phase. Such a preparation phase allows neighboring cells to determine whether they have the capacity to accept additional UEs (e.g., whether to acknowledge handover) and reserve resources for the UE.

[0049] Then, in the execution phase, the UE is instructed to switch from the source cell to the target cell via a handover command message (e.g., an RRCReconfiguration message). This involves, for example, reconfiguring the UE's radio resources to establish a connection with a target base station of the target radio cell. The UE then reconfigures and connects to the new target base station accordingly, performing synchronization and (e.g., contention-free) random access procedures in the process. For example, synchronization may involve the UE acquiring synchronization signals (e.g., a Primary Synchronization Signal (PSS) and a Secondary Synchronization Signal (SSS)) that are typically used to acquire the cell identity and frame timing of the target cell, thereby achieving time and frequency synchronization. A random access procedure may be performed by the UE to, for example, obtain a timing advance value and acquire uplink resources for uplink transmission using an RAR message. The random access procedure may consist of, for example, transmitting a RACH preamble (e.g., a dedicated preamble (following the preamble indicated in the handover command message for contention-free RACH)), receiving a Random Access Response message (e.g., including an uplink grant), and, as the third and final step of the random access procedure, confirming that the UE has completed reconfiguration and access to the target cell by transmitting an RRCReconfigurationComplete message to the target gNB.

[0050] An example implementation of such a handover procedure is defined for RRC connection mobility in 5G NR in section 9.2.3.2 of TS 38.300, version 17.1.0.

[0051] The handover command message may include information about the target cell, such as a target cell ID and setting information for enabling connection to the target cell, as well as handover acceptance conditions and handover rejection conditions.

[0052] As an example and simplified overview, the RRCReconfiguration message: Target Cell ID New C-RNTI Target gNB security algorithm identifier for the selected security algorithm Dedicated RACH resources Common RACH resources Associating RACH resources with SSB Target cell system information It may include one or more of:

[0053] According to a more detailed exemplary definition of the possible contents of a handover command message, 5G NR defines the RRCReconfiguration message in section 6.2.2 of v17.1.0 of 3GPP TS 38.331. According to 5G, the RRCReconfiguration message is a command to modify the RRC connection. The RRCReconfiguration message may convey information for measurement configuration, mobility control, radio resource configuration (including radio bearer (RB), medium access control (MAC) primary configuration and physical channel configuration), and access stratum (AS) security configuration.

[0054] Conditional Handover (CHO) In the legacy handover procedure, the gNB is responsible for determining whether a handover should be performed. This handover procedure is a passive process that is prone to handover failures. For example, if the radio link degrades and the mobile terminal needs to send a measurement report, the measurement report may not reach the network. Or, even if it does, the network attempts to respond with a handover command that may never reach the mobile terminal because the downlink is degraded and / or the handover command is too large and requires multiple transmissions.

[0055] Conditional Handover (CHO), one of the key mobility enhancements specified by 3GPP in Rel-16, focuses on reducing the number of failures that occur during user mobility, for example, when inter-cell handovers fail or when connectivity fails before HO is triggered. In this way, CHO improves mobility robustness for handovers. Furthermore, it can reduce signaling and handover delays. CHO can be used to change the PCell for either a UE without dual connectivity or a master cell group for a UE with dual connectivity. In DC (dual connectivity), a PCell change procedure can be performed to change the PCell of the master cell group.

[0056] Due to its convenience, CHO is being considered in many areas where cellular communications are applied, including, for example, Mobile Broadband (MBB), Non-Terrestrial Networks (NTN), integrated access backhaul, and NR-unlicensed.

[0057] In a conditional handover, the mobile terminal receives a handover command (e.g., an RRCReconfiguration message containing conditional configuration information prepared by the target candidate cell) from the source gNB. Upon receipt, the mobile terminal stores the settings in the handover command rather than applying them immediately as in a legacy handover. Along with the handover command, the mobile terminal also receives associated conditions that are monitored by the mobile terminal. The mobile terminal only applies the stored command if the conditions are met. The mobile terminal then performs the handover and connects to the target node, similar to a normal handover.

[0058] As an example, the source gNB may be responsible for preparing the conditional handover, including execution conditions for when the UE will perform (i.e., trigger) the CHO, while the candidate target gNB provides the CHO configuration parameters to be forwarded by the source gNB to the mobile terminal.

[0059] An exemplary basic CHO procedure is illustrated by the signaling diagram in FIG. 8. As can be seen, the source gNB prepares CHO together with the target gNB. The target gNB provides the source gNB with corresponding target cell-specific configuration parameters. The source gNB sends a CHO command to the UE, including the target cell configuration and execution conditions for the target cell. Upon receiving the CHO command, the UE does not detach from the source gNB (unlike legacy handover); instead, the UE continues exchanging UL and DL data with the source gNB until the CHO execution conditions are met. Once the execution conditions for the target cell are met, the UE begins executing CHO (e.g., in a manner similar or equivalent to legacy handover).

[0060] According to one example, the configuration parameters of the target gNB are: Radio resource configuration of candidate target cells, such as resource blocks and physical channel configuration Security settings of candidate target cells Dual connectivity information such as master cell group information, secondary cell group information, etc. Measurement configuration of candidate target cells Mobility information (including, for example, handover settings and conditional settings) may include one or more of:

[0061] Another exemplary and simplified CHO procedure is illustrated in more detail by the signaling diagram of FIG. 9 compared to the basic signaling diagram of FIG. 8. Accordingly, the source gNB prepares the CHO based on, for example, measurements received from a mobile terminal. Thus, the source gNB identifies gNB1 as a potential target for the CHO and sends a handover request (here, CHO Request) to the target gNB (e.g., in 5G, for example, according to TS 38.423 v17.1.0, the corresponding CHO-related IE in the handover request message is the IE called "Conditional Handover Information Request"). The target gNB processes the received handover request (e.g., performs admission control), and once the target gNB allows the mobile terminal to access the cell, the target gNB sends an appropriate CHO response message (CHO ACK) to the source gNB. As an example, the shared CHO configuration may include one or more requested target cell IDs and the maximum number of CHO preparations (see section 9.1.1.2 of TS 38.423 v17.1.0). In general, the CHO ACK message may contain the configuration information required to access the target cell (e.g. in the form of a handover request acknowledgement message, e.g., XnAp, Xn Application Protocol, signaling message according to the 3GPP standard TS 38.423).

[0062] In this embodiment, when the source gNB receives a CHO ACK from the target cell, it determines the appropriate CHO execution conditions.

[0063] The source gNB then transmits a CHO configuration to the mobile terminal, which includes, for example, configuration information for accessing the target cell (the configuration information received by the source gNB from the target gNB) and the determined CHO execution condition, both of which are stored by the mobile terminal. Thus, the mobile terminal is provided with information necessary to perform the conditional handover. For example, the UE may store the CHO information in a memory.

[0064] Therefore, instead of immediately performing a handover, the mobile terminal first maintains its connection to the source gNB and begins evaluating the CHO execution conditions for the target cell.

[0065] Finally, when the CHO execution conditions are met, the UE performs handover to the target cell, which may include, for example, the UE detaching from the source gNB, applying stored configurations corresponding to the target cell, synchronizing to the target cell, and completing the handover (e.g., sending an RRCReconfigurationComplete message to the target gNB). The target cell may notify the source gNB that the UE has successfully accessed the target cell (see the CHO Execution Indication message in FIG. 9). One example is another XnAp message, such as the Handover Success signaling message of 3GPP TS 38.423.

[0066] There are several options for how to implement the condition for CHO. The condition shall define criteria such as when to apply the stored handover command, and the criteria shall be based, for example, on the quality of the serving and neighboring cells (somewhat similar to the conditions that lead the mobile terminal to send a measurement report when the condition is met). However, instead of triggering the transmission of a measurement report, the UE triggers CHO towards the target cell.

[0067] For example, the network can be configured to cause the wireless terminal to perform CHO when a neighboring cell has a better offset than the serving cell (e.g., similar to event A3), or when the serving cell is worse than a first threshold and the neighboring cell is better than a second threshold (e.g., similar to event A5). Measurements for determining cell quality can be based on measurements such as quality represented by Radio Signal Received Power (RSRP), Radio Signal Received Quality (RSRQ), and Signal to Interference and Noise Ratio (SINR). Two (or more) (sub)conditions can also be configured for the mobile terminal, and these multiple (sub)conditions can be associated with stored commands. That is, the command is applied only if all (sub)conditions are met.

[0068] As a further example of CHO, if a CHO configuration is configured in a UE and another (legacy) HO command is received from a gNB before the CHO execution conditions are met, the UE performs handover based on the received (legacy) HO command and does not wait for any of the CHO conditions to be met. In short, legacy handover takes priority over CHO.

[0069] According to one embodiment, the illustrated CHO configuration includes a configuration of CHO candidate cells (generated by the candidate gNB) and respective execution conditions (generated by the source gNB). For example, the CHO candidate cell configuration may include a candidate cell list with corresponding cell IDs and carrier frequencies of the candidate cells. The execution conditions may include CHO-related trigger events, such as the A3 / A5 events mentioned above, and trigger quantities (e.g., RSRP and RSRQ, RSRP and SINR, etc.).

[0070] An exemplary 5G compliant implementation of conditional handover is briefly described below, but more detailed information is available from 3GPP technical specifications including, for example, TS 38.331 v17.1.0, 38.300 v17.1.0, and 38.423 v17.1.0.

[0071] TS 38.331 defines the RRCReconfiguration procedures and messages used as part of CHO, as well as the corresponding UE behavior (e.g., Sections 5.3.5, 5.3.5.1, 5.3.5.2, 5.3.5.3, and 5.3.5.4). Conditional reconfiguration is defined in Section 5.3.5.13 of TS 38.331 and is used by the network to configure one or more candidate SpCells for the UE. The network provides the configuration parameters for the target SpCell in the ConditionalReconfiguration IE as part of the RRCReconfiguration IE. The ConditionalReconfiguration IE provides the configuration of candidate target SpCells and execution conditions for conditional handover, conditional PSCell addition (CPA, described below), and conditional PSCell modification (CPC, described below).

[0072] <conditionalreconfiguration> The IE "ConditionalReconfiguration" is used to add, change, and remove conditional reconfiguration settings. [Table 1] [Table 2] [Table 3]

[0073] <condreconfigtoaddmodlist> The IE "CondReconfigToAddModList" relates to the list of conditional reconfigurations to add or modify and for each entry contains a condReconfigId and an associated condExecutionCond / condExecutionCondSCG and condRRCReconfig. [Table 4] [Table 5] [Table 6]

[0074] <condreconfigid> The IE "CondReconfigId" is used to identify the configuration of a CHO, CPA, or CPC. [Table 7] Furthermore, TS 38.331 defines the ReportConfigNR IE in section 6.3.2, which specifies the criteria for triggering a CHO, CPA, or CPC event.

[0075] TS 38.300 defines conditional handover in Section 9.2.3.4 as a handover performed by a UE when one or more handover execution conditions are met. The UE starts evaluating the execution conditions when it receives the CHO configuration and stops evaluating the execution conditions when the handover is executed. Furthermore, the execution conditions can consist of one or two trigger conditions. Only a single RS type is supported, and up to two different trigger quantities (e.g., RSRP and RSRQ, RSRP and SINR, etc.) can be simultaneously configured for the evaluation of the CHO execution conditions for a single candidate cell. Section 16.4.3.2.2 describes CHO as it applies to non-terrestrial networks.

[0076] As an example of a typical conditional handover, instead of having only one target cell as in the legacy case, multiple candidate target cells can be pre-provisioned within the network. This can be beneficial because handover delays can lead to uncertainty about the specific target cell that the mobile terminal will access. In response, the mobile terminal receives various target cell configurations and CHO trigger conditions for each monitored target cell configuration. When the conditions for one of the configured candidate target cells are met, the mobile terminal performs a handover to that target node based on the target cell configuration already received.

[0077] CHO in a scenario with multiple candidate target cells (here, two candidate target cells, gNB1 and gNB2) is shown in Figure 10. Figure 10 is a signaling diagram similar to that shown in Figure 9, which illustrates a scenario with one candidate target cell. The signaling diagram is mostly similar to Figure 9, except that CHO preparation is performed for the two candidate target cells and controlled by gNB1 and gNB2, respectively. As is clear from Figure 10, CHO preparation, including CHO request and CHO ACK, is shown simplified as a double-sided arrow for the two candidate target cells, gNB1 and gNB2.

[0078] The source gNB determines the CHO execution conditions for each candidate target cell and provides the mobile terminal with the CHO configurations and each CHO execution condition for both candidate target cells.

[0079] Furthermore, it is exemplarily assumed that the source gNB transmits the CHO configurations of the two candidate target cells and the CHO execution conditions for each CHO configuration together to the UE, or these may be transmitted separately to the UE for each candidate target cell.

[0080] In the scenario of Figure 10, it is exemplarily assumed that the mobile terminal determines that the CHO execution conditions for the target gNB2 are met and therefore performs a handover to the target cell of gNB2.

[0081] The conditional handover procedure in Figure 10 further includes two important steps. First, after the CHO is successfully completed, the UE releases (e.g., deletes from storage) all CHO configurations and CHO execution conditions, including those of gNB1's candidate target cells for which CHO was not triggered. Second, upon receiving a CHO execution notification message from target cell gNB2, the source gNB notifies gNB1 that the CHO of the mobile terminal has been canceled. This allows gNB1 to release any resources that may have been reserved for a potential CHO of the mobile terminal.

[0082] <Conditional PSCell change> 3GPP Release 16 also introduces the Conditional PSCell change procedure (CPC) to improve mobility robustness of PSCell changes in dual connectivity scenarios.

[0083] In DC (dual connectivity, e.g., MR-DC), a PSCell change procedure can be performed to change the PSCell of the secondary cell group. In one example, the PSCell may depend on whether a security key change is required.

[0084] Similar to CHO, a conditional PSCell change (CPC) is executed only if the corresponding CPC execution condition is met.

[0085] CPC reuses many of the features of the conditional handover described above (see TS 37.340 v17.1.0, section 10.1).

[0086] The UE completes the CPC execution procedure with an RRCReconfigurationComplete message to the Master Node (MN) (of the MCG). If SRB3 is not configured, it contains an embedded RRCReconfigurationComplete message for the new PSCell, otherwise the UE sends the RRCReconfigurationComplete directly to the new PSCell.

[0087] A 5G compliant implementation is specified in TS 37.340 v17.1.0, which provides details of CPC in section 10.6 as follows:

[0088] The CPC configuration includes the configuration and execution conditions of the CPC candidate PSCell, and may include the MCG configuration for inter-SN CPC that is applied when CPC execution is triggered.

[0089] An execution condition may consist of, for example, one or two trigger conditions (CondEvents) (defined in TS 38.331 or TS 36.331). The evaluation of the CPC execution condition for a single candidate PSCell may use only a single Reference Signal (RS) type or up to two different trigger quantities (e.g., RSRP and RSRQ, RSRP and SINR, etc.).

[0090] If the UE receives a PSCell change command or a PCell change command before any of the CPC execution conditions are met, the UE shall perform the PSCell change procedure described in clauses 10.3 and 10.5 of TS 38.300 or the PCell change procedure described in clause 9.2.3.2 of TS 38.300 or clause 10.1.2.1 of TS 36.300, regardless of the previously received CPC setting.

[0091] While executing the CPC, the UE does not need to continue evaluating the execution conditions of other candidate PSCells.

[0092] If the CPC procedure is successfully performed, the UE shall release all stored conditional reconfigurations (eg, conditional reconfigurations for CPC and CHO as specified in TS 38.300 or TS 36.300).

[0093] When the SCG is released, the UE releases the stored CPC settings.

[0094] In Release 16, the CPC procedure was limited to intra-SN changes without MN involvement. 3GPP Release 17 introduced support for inter-SN conditional PSCell change (CPC).

[0095] FIG. 11 shows an exemplary simplified signaling diagram of the CPC procedure. As can be seen from FIG. 11, the source gNB prepares CPC with both candidate target cells, gNB1 and gNB2. Preparation may include, for example, the source gNB receiving CPC configuration parameters for each of gNB1 and gNB2 and determining CPC execution conditions for each of the two CPC candidates. The two CPC configurations (including the CPC configuration parameters and each CPC execution condition) are then transmitted from the source gNB to the UE. The UE evaluates the CPC execution conditions for the two candidates rather than immediately changing the PSCell to one of the two candidate target cells. Finally, the UE determines that the CPC execution condition for target gNB2 is met and changes the PSCell to gNB2's cell. Upon successful completion of CPC, the UE releases the two CPC configurations, including the CPC configuration for gNB1 on which CPC was not performed.

[0096] <Conditional PSCell addition> 3GPP also introduces the Conditional PSCell Addition (CPA) procedure to improve mobility robustness when creating a new secondary cell group. According to CPA, a PSCell is added for a secondary cell group in a dual connectivity scenario, and the UE connects to a new PSCell in the SCG in addition to a cell in the MCG. In one example, the additional PSCell can be a PSCell of a different radio access technology than the current PSCell. CPA can also be used to add another SCell to an SCG. Furthermore, under dual connectivity, multiple SCGs can be established for a UE, but only one SCG can be active at a time. Therefore, CPA can also be used to create another SCG that is initially in a disabled state but has another PSCell.

[0097] Similar to CHO, Conditional PSCell Addition (CPA) is defined as a PSCell addition that is executed by the UE only if the corresponding CPA execution condition is met. When the UE receives a CPA configuration, it starts evaluating the execution condition, and when a PSCell addition or PCell change is triggered, it stops evaluating the execution condition.

[0098] CPA reuses many of the features of the conditional handover described above (see TS 37.340 v17.1.0, section 10.1).

[0099] In one embodiment, the CPA procedure is used to establish a connection between the UE and an additional PSCell of the newly created SCG, including the configuration parameters of the PSCell.

[0100] Section 10.2.3 of TS 37.340 v17.1.0 discloses conditional PSCell addition as part of the secondary node addition in Section 10.2. According to this 5G-compliant embodiment, the CPA configuration includes the configuration of the CPA candidate PSCell, the execution conditions, and may include the MCG configuration to be applied when CPA execution is triggered. The execution conditions may consist of one or two trigger conditions (CondEvents) (defined in TS 38.331 [4] or TS 36.331

[10] ). The evaluation of the CPA execution conditions for a single candidate PSCell can use only a single RS type, or up to two different trigger quantities (e.g., RSRP and RSRQ, RSRP and SINR, etc.).

[0101] If the UE receives a normal (i.e., non-conditional) PSCell addition or PCell modification command before any of the CPA execution conditions are met, it shall perform the PSCell addition procedure described in clause 10.2.1 or 10.2.2 of TS 38.300 or the PCell modification procedure described in clause 9.2.3.2 of TS 38.300 or 10.1.2.1 of TS 36.300, regardless of the previously received CPA configuration. Upon successful completion of the PSCell addition or PCell modification procedure, the UE shall release the stored CPA configuration.

[0102] While performing CPA, the UE does not need to continue evaluating the execution conditions of other candidate PSCells.

[0103] If the CPA procedure is successfully performed, the UE releases all stored conditional reconfigurations (i.e., conditional reconfigurations for CPA and CHO as specified in TS 38.300 or TS 36.300). It does not support CPA configuration in HO commands, PSCell addition commands, or conditional configurations (i.e., configuration of CPA, CPC, or CHO).

[0104] An exemplary and simplified signaling diagram of the CPA procedure is shown in Figure 12. As can be seen from the diagram, the source gNB (which can therefore be considered a cell of the master cell group) prepares CPA with both candidate target cells, gNB1 and gNB2. Preparation may include, for example, the source gNB receiving CPA configuration parameters for each of gNB1 and gNB2 and determining CPA execution conditions for each of the two CPA candidates. The two CPA configurations (including the CPA configuration parameters and respective CPA execution conditions) are then transmitted from the source gNB to the UE. The UE evaluates the CPA execution conditions for the two candidates rather than immediately adding the PSCell for gNB1 or gNB2. Finally, the UE determines that the CPA execution conditions for target gNB2 are satisfied and creates an SCG with the PSCell for gNB2. Upon successful completion of CPA, the UE releases the two CPA configurations, including the CPA configuration for gNB1 on which CPA was not performed.

[0105] <Further improvements> Above we have described the mobility extensions for CHO, CPC, and CPA introduced by 3GPP Releases 16 and 17. Further extensions to NR mobility are envisioned in Release 18.

[0106] The inventors identified problems with the current definitions of the CHO, CPC, and CPA procedures. In particular, the current Release 16 and 17 NR specifications require the UE to deconfigure CHO / CPC / CPA, respectively, upon successful completion of the corresponding procedures.

[0107] For example, as shown in FIG. 10, once the CHO is successfully completed, the UE releases all CHO configurations, including the CHO configuration parameters and CHO execution conditions.

[0108] As shown in FIG. 11, when the CPC is successfully completed, the UE releases all CPC configurations, including the CPC configuration parameters and the CPC execution conditions.

[0109] As shown in FIG. 12, when the CPA is successfully completed, the UE releases all CPA configurations, including the CPA configuration parameters and the CPA execution conditions.

[0110] As a result, the network and the UE need to reconfigure and reinitialize the CHO / CPC / CPA so that another subsequent CHO / CPC / CPA can be performed, as described above in relation to Figures 10, 11 and 12, respectively.

[0111] This increases the signaling overhead: after each successful CHO / CPC / CPA procedure, the UE needs to receive again the complete set of configuration parameters and execution conditions for each candidate cell.

[0112] Furthermore, this may lead to increased delays in the CHO / CPC / CPA procedure, as the UE must first be configured after successfully completing CHO / CPC / CPA before being able to run CHO / CPC / CPA again.

[0113] The above drawbacks are particularly noticeable in cases where there are frequent cell changes, for example, when operating in FR2 (which includes the frequency band from 24.25 GHz to 71.0 GHz).

[0114] The inventors have thus found the possibility of providing improved mobility procedures (CHO, CPC, CPA, etc.) that make it possible to avoid one or more of the above-mentioned disadvantages. The present invention relates to various solutions and variants for such improved mobility procedures.

[0115] <Embodiment> In the following, UEs, base stations, and procedures for meeting these needs are described for new radio access technologies envisioned for 5G mobile communication systems, but may also be used in previous LTE mobile communication systems or future mobile communication systems. Various implementations and variations are also described. The following disclosure is facilitated by, and may be based, for example, at least in part on, the above discussion and findings.

[0116] In general, it should be noted that many assumptions have been made herein and will be made hereinafter in order to be able to explain the principles underlying the present disclosure in a clear, concise, and understandable manner. However, these assumptions should be understood as merely examples made herein for the purpose of explanation, and they are not necessarily essential to the present invention, and therefore should not limit the scope of the present disclosure. Those skilled in the art will recognize that the principles of the following disclosure and claims can be applied in different scenarios and in ways not explicitly described herein.

[0117] Furthermore, although some of the terms used below, such as procedures, entities, and layers, are closely related to those used in the LTE / LTE-A system or the current 3GPP 5G standardization, specific terms used in the context of new radio access technologies for upcoming communication systems have not yet been fully determined or may eventually change. Thus, terms may change in the future without affecting the functionality of the embodiments. As a result, those skilled in the art will recognize that the embodiments and their scope of protection should not be limited to the specific terms used exemplified in this specification, which lack newer or final agreed-upon terms, but should be more broadly understood by the functions and concepts underlying the solutions described in this disclosure.

[0118] For example, a mobile station or mobile node or user terminal or user equipment (UE) is a physical entity (physical node) in a communication network. A node may have several functional entities. A functional entity refers to a software or hardware module that implements and / or provides a predetermined set of functions to other functional entities of the same or another node or network. A node may have one or more interfaces that attach the node to a communication facility or medium that allows the node to communicate. Similarly, a network entity may have logical interfaces that attach a functional entity to a communication facility or medium that allows the node to communicate with other functional entities or corresponding nodes.

[0119] The term "base station" or "radio base station" in this specification refers to a physical entity in a communication network. Similar to a mobile station, a base station may have several functional entities. A functional entity refers to a software or hardware module that implements and / or provides a predetermined set of functions to other functional entities of the same or another node or network. A physical entity performs several control tasks for communication devices, including one or more of scheduling and configuration. Note that base station functionality and communication device functionality may be integrated within a single device. For example, a mobile terminal may also implement base station functionality for other terminals. While the term used in LTE is eNB (or eNodeB), the term currently used for 5G NR is gNB. A base station may also be a gNB in a Non-Terrestrial Network (NTN) NR system.

[0120] Communication between a UE and a base station is typically standardized and may be defined by different layers, such as PHY, MAC, RRC, etc. (see background discussion above).

[0121] Here, the expression "cell configuration" can be understood as a configuration of a cell that can be used in the context of executing a cell mobility procedure such as a CHO procedure, a CPC procedure or a CPA procedure. By way of example, the cell configuration comprises a complete set of parameters of the cell and "execution conditions" and limits the execution of the cell mobility procedure to the fulfillment of the conditions.

[0122] The expression "cell configuration parameters" refers to parameters related to a cell (more precisely, a candidate target cell), which can be used to perform a conditional cell mobility procedure for that cell.

[0123] The expression "candidate target cell" may be understood to refer to a cell that is a candidate for being subject to a conditional cell mobility procedure. There may be one or more candidate target cells, one of which is likely to be the actual target cell of the conditional cell mobility procedure.

[0124] The expression "conditional cell mobility procedure" can be understood to include mobility procedures relating to different cells, the execution of which is not immediate but depends on the fulfillment of execution conditions. Examples of conditional cell mobility procedures include conditional handover (CHO, see e.g., CHO in the 5G standard described above), conditional cell change (CPC, see e.g., CPC in the 5G standard described above), or conditional cell addition (CPA, see e.g., CPA in the 5G standard described above).

[0125] The term "cancel" can be understood, for example, in relation to the cancellation of a setting, for example, to "delete" a (stored) setting.

[0126] The term "maintain" can mean, for example, in relation to maintaining a setting, for example, being set not to be released, for example, not releasing the setting.

[0127] 13 shows a general, simplified, exemplary block diagram of a user equipment (also referred to as a communication device) and a scheduling device (here assumed for purposes of illustration to be located in a base station such as an LTE eNB (also known as an ng-eNB) or a gNB in 5G NR). The UE and the eNB / gNB communicate with each other via a (wireless) physical channel using their respective transceivers.

[0128] A communication device may include a transceiver and a processing circuit. The transceiver may include and / or function as a receiver and a transmitter. The processing circuit may be one or more hardware components, such as one or more processors or any LSI. An input / output point (or node) exists between the transceiver and the processing circuit, and the processing circuit can control the transceiver through this input / output point during operation, i.e., control the receiver and / or transmitter to exchange receive / transmit data. The transceiver may include an RF (radio frequency) front end, including one or more antennas, amplifiers, and RF modulators / demodulators, as the transmitter and receiver. The processing circuit may perform control tasks, such as controlling the transceiver to transmit user data and control data provided by the processing circuit and / or receive user data and control data that are further processed by the processing circuit. In addition, the processing circuit may be responsible for performing other processes, such as judgment, decision, calculation, and measurement. The transmitter may be responsible for performing the transmission process and other processes related thereto. The receiver may be responsible for performing the reception process and other processes related thereto, such as monitoring the channel.

[0129] Various solutions for improved mobility procedures are described below. In this connection, an improved UE, an improved base station, and an improved integrated circuit are presented, which participate separately or together in the improved mobility procedures. Corresponding methods for UE behavior and base station behavior are also provided. The integrated circuit corresponds to the UE and base station and their respective behaviors.

[0130] Two solutions for improved mobility procedures are presented, the first of which is described with reference to Figures 14 to 23, and the second of which is described with reference to Figures 24 to 28 (including reference to the description of Figure 21).

[0131] <First Solution> Figure 14 illustrates a simplified exemplary UE structure for one exemplary implementation of improved mobility procedures, which may be implemented based on the general UE structure described in connection with Figure 13. The various structural elements of the UE illustrated in Figure 14 may be interconnected with each other, e.g., by corresponding input / output nodes (not shown), for example, to exchange control and user data and other signals. Although not shown for purposes of illustration, the UE may include additional structural elements.

[0132] As can be seen from FIG. 14, the UE may include a cell configuration receiving unit (for receiving a plurality of cell configurations including cell configuration parameters and execution conditions), an execution condition evaluation circuit, and a conditional cell mobility procedure circuit.

[0133] In this case, the receiver of the UE may be configured to at least partially perform one or more of, for example, receiving a plurality of cell configurations of a plurality of candidate target cells, and further, as will become clear from the disclosure below, receiving one of the notifications regarding which subset to use for evaluation.

[0134] As will become apparent from the present disclosure, the processing circuitry of the UE may be configured to at least partially perform one or more of, for example, performing a conditional cell mobility procedure if an enabling condition is met, evaluating the enabling condition, maintaining the received plurality of cell configurations, etc.

[0135] As will become apparent from the disclosure below, in this case, the transmitter of the UE can be illustratively configured to at least partially perform one or more of the following: send measurement reports to the UE's serving cell.

[0136] One exemplary procedure, disclosed in further detail below, is implemented by a UE including: a receiver of the UE receives, from a source base station, multiple cell configurations for multiple candidate target cells; each cell configuration includes cell configuration parameters for performing a conditional cell mobility procedure for each candidate target cell and an execution condition for when to perform the conditional cell mobility procedure for each candidate target cell; the multiple cell configurations include a first subset of cell configurations that are evaluated by the UE when the UE is connected to the source base station; and the multiple cell configurations include a second subset of cell configurations that are evaluated by the UE when connected to a first candidate target cell of the multiple candidate target cells that is different from the source cell of the source base station. A circuit of the UE evaluates the execution condition for only the first subset of cell configurations. The circuit performs the conditional cell mobility procedure for the first candidate target cell based on the cell configuration parameters of the first candidate target cell if the evaluated execution condition for the cell configurations of the first subset of cell configurations for the first candidate target cell is satisfied.

[0137] A corresponding exemplary method is performed by a UE receiving, from the source base station, a plurality of cell configurations for a plurality of candidate target cells, each cell configuration including cell configuration parameters for performing a conditional cell mobility procedure for each candidate target cell and an execution condition for when to perform the conditional cell mobility procedure for each candidate target cell; receiving a plurality of cell configurations including a first subset of cell configurations to be evaluated by the UE when the UE is connected to a source base station, and a plurality of cell configurations including a second subset of cell configurations to be evaluated by the UE when the UE is connected to a first candidate target cell of a plurality of candidate target cells, the first candidate target cell being different from a source cell of the source base station; evaluating only the execution conditions of a first subset of the cell configurations; and performing a conditional cell mobility procedure based on cell configuration parameters of the first candidate target cell if the evaluated execution conditions of the cell configurations of the first subset of cell configurations are satisfied for the first candidate target cell.

[0138] A sequence diagram corresponding to exemplary UE behavior along the UE and UE methods discussed above is shown in FIG.

[0139] Thus, the improved mobility procedure described above achieves its objectives and overcomes some of the drawbacks mentioned above. For example, the improved mobility procedure involves a UE having multiple cell configurations, including different subsets used in different serving cells. Accordingly, the UE processes only the appropriate subset of cell configurations for the current serving cell. Because the various subsets of cell configurations used in other cells are already available to the UE before the conditional cell mobility procedure is performed, the improved mobility procedure allows for a faster subsequent conditional cell mobility procedure. Furthermore, after performing the conditional cell mobility procedure, signaling overhead with the UE is saved because the new serving cell does not need to send the appropriate cell configuration to be evaluated by the UE, considering that the corresponding subset of cell configurations is already available to the UE.

[0140] Some exemplary embodiments of the improved mobility procedure include improved base stations, particularly an improved source base station to which the UE is currently connected (e.g., referred to as a serving base station because it serves the UE), and an improved target base station that is the subject of the conditional cell mobility procedure. Accordingly, the improved mobility procedure also provides for improved base stations that participate in the mobility procedure, as described below.

[0141] Figure 16 illustrates a simplified exemplary source base station structure according to one exemplary implementation of the improved mobility procedures, which may be implemented based on the general base station structure described in connection with Figure 13. The various structural elements of the source base station illustrated in Figure 16 may be interconnected with each other, e.g., by corresponding input / output nodes (not shown), e.g., for exchanging control and user data and other signals. Although not shown for purposes of illustration, the source base station may include additional structural elements.

[0142] As is clear from this, the source base station includes a cell setting transmission unit (initial cell setting includes cell setting parameters and execution conditions) and a cell setting preparation circuit.

[0143] In this case, as will become apparent from the present disclosure, the receiver of the source base station can be exemplarily configured to at least partially perform one or more of the receiving of the requested cell configuration parameters, etc.

[0144] As will become apparent from the present disclosure, the processing circuitry of the source base station can be configured to at least partially perform one or more of, for example, generating a plurality of cell configurations, determining cell configuration parameters for each candidate target cell, etc.

[0145] In this case, as will become apparent from the present disclosure, the transmitter of the source base station may be configured to at least partially perform one or more of, for example, sending a cell configuration to the UE, sending a request to a candidate target cell requesting cell configuration parameters, etc.

[0146] An example procedure, as disclosed in more detail below, is performed by a source base station, including: circuitry in the source base station generates a plurality of cell configurations for a plurality of candidate target cells; each cell configuration has cell configuration parameters for performing a conditional cell mobility procedure between a user equipment (UE) and each candidate target cell, and an execution condition for when to perform the conditional cell mobility procedure for each candidate target cell; the plurality of cell configurations includes a first subset of cell configurations to be evaluated by the UE when the UE is connected to the base station; the plurality of cell configurations includes a second subset of cell configurations to be evaluated by the UE when connected to a first candidate target cell of the plurality of candidate target cells, the first candidate target cell being different from the source cell of the base station; and a transmitter transmits the generated plurality of cell configurations to the UE.

[0147] A corresponding method includes the following steps, which are performed by a source base station.

[0148] receiving, from a source base station, a request for cell configuration parameters of the base station for performing a conditional cell mobility procedure between a user equipment (UE) connected to the source base station and the base station; generating, upon receiving the request, a cell configuration for at least one other candidate target cell, the cell configuration for the other candidate target cell including cell configuration parameters of the other candidate target cell to be used by the UE when the UE is connected to the base station and an execution condition regarding when to perform conditional cell mobility between the UE and the other candidate target cell when the UE is connected to the base station. transmitting the generated cell configuration of the at least one other candidate target cell to the source base station; A sequence diagram corresponding to an exemplary source base station operation in accordance with the source base station and corresponding method discussed above is shown in Figure 17. This sequence diagram illustrates an exemplary simplified implementation of the source base station method presented above.

[0149] Figure 18 shows a simplified exemplary target base station structure for an exemplary implementation of the improved mobility procedure, which can be implemented based on the general base station structure described in relation to Figure 13. The various structural elements of the target base station shown in Figure 18 can be connected to each other, for example, by corresponding input / output nodes (not shown) for exchanging control and user data and other signals. Although not shown, the target base station may include additional structural elements.

[0150] As is apparent from this, the target base station includes a receiver for receiving a cell setting parameter request, and a cell setting generation circuit.

[0151] In this case, which will become clear from the present disclosure, the receiver of the target base station can be configured to at least partially perform one or more of, for example, receiving a request for cell configuration parameters from another base station, receiving cell configuration parameters, etc.

[0152] In this case, as will become apparent from the present disclosure, the processing circuitry of the target base station may be configured to at least partially perform one or more of, for example, performing a conditional cell mobility procedure, generating a cell configuration, etc.

[0153] In this case, which will become apparent from the present disclosure, the transmitter of the target base station may be configured to at least partially perform one or more of the transmissions, for example the generated cell configuration.

[0154] As disclosed in more detail below, an example procedure is performed by a target base station, including: a receiver of the target base station receives a request from a source base station requesting cell configuration parameters of the base station for performing a conditional cell mobility procedure between a user equipment (UE) connected to the source base station and the target base station; a circuit of the target base station generates a cell configuration of at least one other candidate target cell upon receiving the request; the cell configuration of the other candidate target cell includes cell configuration parameters of the other candidate target cell that the UE uses when the UE is connected to the base station and an execution condition regarding when to perform conditional cell mobility between the UE and the other candidate target cell when the UE is connected to the base station; a transmitter of the target base station transmits the generated cell configuration of the at least one other candidate target cell to the source base station.

[0155] The corresponding method is performed by the target base station. receiving, from a source base station, a request for cell configuration parameters of the base station for performing a conditional cell mobility procedure between a user equipment (UE) connected to the source base station and the base station; generating, upon receiving the request, a cell configuration of at least one other candidate target cell, the cell configuration of the other candidate target cell including cell configuration parameters of the other candidate target cell to be used by the UE when the UE is connected to the base station and an execution condition regarding when to perform conditional cell mobility between the UE and the other candidate target cell when the UE is connected to the base station; sending the generated cell configuration of at least one other candidate target cell to the source base station; Includes:

[0156] A corresponding sequence diagram for an exemplary target base station behavior in accordance with the target base station and corresponding method described above is shown in Figure 19. The sequence diagram illustrates an exemplary simplified implementation of the target base station method described above.

[0157] As described above, the improved UE, improved source base station, and improved target base station achieve the objectives, overcome some of the identified problems, and achieve advantages by participating in improved mobility procedures.

[0158] An improved mobility procedure involving the above-mentioned improved devices is described below.

[0159] For purposes of explanation and illustration, we first exemplarily assume that the improved mobility procedure is an improved conditional handover procedure (improved CHO procedure). In general, conditional handover can be understood as a procedure in which, upon satisfying a condition, a UE disconnects from a source cell and connects to one candidate target cell (potentially selected from many candidates). Conditional handover can be used regardless of whether the UE is in dual connectivity. Thus, CHO can be used to change the UE's primary cell, and in dual connectivity, to change the UE's primary cell when the primary cell is part of the UE's master cell group.

[0160] However, this notion of CHO as an improved conditional cell mobility procedure should not be understood to mean that the improved mobility procedure should be limited to conditional handovers only. Rather, the principles underlying the improved mobility procedure are also applicable to other conditional cell mobility procedures, such as conditional cell change procedures (e.g., see CPC above) and conditional cell addition procedures (e.g., see CPA above). A more detailed description of the improved CPC and improved CPA procedures is provided below.

[0161] Figure 20 is a signaling diagram of an exemplary simplified implementation of the improved CHO procedure, showing the exchange of messages between the different participating entities (here UE, gNB0, gNB1, and gNB2) and the steps performed by these entities.

[0162] Assume that the UE is currently connected to the source gNB0. According to the improved CHO procedure, however, the CHO preparation by the source gNB is significantly different from the corresponding CHO preparation in the prior art, as shown in Figures 9 and 10. In particular, the CHO preparation includes the preparation of multiple CHO configurations for possible candidate target cells gNB1 and gNB2. Thus, the multiple CHO configurations may include a CHO configuration to be used by the UE when the UE is connected to the source cell gNB0. However, according to the improved CHO procedure, the multiple CHO configurations may also include a CHO configuration that is not currently used by the UE when connected to the source cell gNB0, but will be used in the future by the UE when connected to another serving cell (e.g., gNB1 or gNB2).

[0163] In other words, the multiple CHO configurations include different subsets of CHO configurations, one subset of CHO configurations being immediately used by the UE connecting to the source cell gNB0, however at least one further subset of CHO configurations of the multiple cell configurations is pre-prepared for later use.

[0164] For example, a multiple CHO configuration may include, in the example scenario of FIG. [Table 8]

[0165] As is apparent from the above table, the multiple CHO configurations include CHO configurations 1 and 2, which are used when the UE is connected to gNB0 (e.g., indicated as "@gNB0"). Accordingly, considering that the UE is currently connected to source gNB0, the UE evaluates CHO configurations 1 and 2 for potential CHO.

[0166] Furthermore, the UE receives CHO configurations 3 and 4, which are respectively prepared for the future, i.e., for when the UE performs a successful CHO to gNB1, and therefore CHO configurations 3 and 4 are not considered by the UE while connected to the source cell of gNB0.

[0167] The above CHO configurations are logically grouped into different subsets of CHO configurations, with subset A defined to include gNB0-related CHO configurations (i.e., CHO configurations used by the UE when the UE is attached to gNB0) and subset B defined to include gNB1-related CHO configurations (i.e., CHO configurations used by the UE when the UE is attached to gNB1).

[0168] In the above table, the multiple CHO configurations 1 do not include pre-prepared CHO configurations for the case where the UE performs CHO to another candidate target cell, gNB2. Therefore, in this case, gNB2 and the UE may need to perform conventional procedures to prepare a CHO configuration to be used by the UE in gNB2 (e.g., see the prior art discussion above with reference to Figures 8-10).

[0169] Meanwhile, as another example, the CHO preparation by the source gNB0 may also include the advance preparation of CHO settings for the CHO of the UE connected to gNB2. In this case, the multiple CHO settings received by the UE may also include the following CHO settings 5 and 6. [Table 9]

[0170] CHO settings 5 and 6 are defined to be associated with subset C which includes all CHO settings related to gNB2 (i.e., CHO settings used by the UE when the UE is connected to gNB2).

[0171] Accordingly, the multiple CHO settings 1 to 6 include one subset for each CHO setting within one subset. For example, from the perspective of subset A, for CHO setting 1, the multiple CHO settings also include subset B for the case where the UE performs CHO according to CHO setting 1. Similarly, from the perspective of subset A, for CHO setting 2, the multiple CHO settings also include subset C for the case where the UE performs CHO according to CHO setting 2.

[0172] Furthermore, each CHO configuration may include cell configuration parameters for performing CHO with each candidate target cell, and may further include execution conditions regarding when to perform the CHO procedure with each candidate target cell. Therefore, conceptually, each CHO configuration may have the same (or similar) content as a CHO configuration used in the prior art.

[0173] The following provides a detailed description of one example of how multiple CHO configurations can be prepared by source gNB0, particularly with reference to FIG.

[0174] In this way, the above-described multiple CHO configurations 1 to 6 include two or more CHO configurations for each candidate target cell, and in this example, include two CHO configurations for each candidate target cell.

[0175] Meanwhile, within one subset, the CHO settings of that subset relate to different candidate target cells, for example, CHO settings 1 and 2 of subset A relate to different candidate target cells gNB1 and gNB2.

[0176] As further apparent from Figure 20, after preparing the multiple CHO configurations, the source gNB0 transmits the same CHO configuration to the UE. The UE then processes the CHO configurations, which are evaluated by the UE when connected to the current serving cell (here, gNB0). In response, the UE evaluates the execution conditions of gNB0-related CHO configurations 1 and 2 to determine whether some of the execution conditions for the CHO configurations are met.

[0177] On the other hand, the UE does not process CHO configurations that do not refer to the current serving cell, i.e., CHO configurations of other subsets of the multiple CHO configurations, here, subsets B and C. Therefore, the UE does not spend resources and time on processing CHO configurations that do not perform CHO.

[0178] When the execution condition of one evaluated CHO configuration is satisfied, the UE performs a CHO procedure with the corresponding candidate target cell of the satisfied CHO configuration. In the example scenario of Figure 20, the UE performs a CHO procedure with the candidate target gNB1. The CHO procedure may be performed based on the configuration parameters of the CHO configuration corresponding to gNB1.

[0179] A further step in the improved CHO procedure involves maintaining multiple CHO configurations 1 through 6 upon successful completion of CHO to gNB1. Therefore, the multiple CHO configurations are not deleted from the UE memory at this point. This contrasts with legacy CHO procedures (e.g., the procedures described in Figures 8, 9, or 10), in which the UE clears all initial CHO configurations upon successful CHO.

[0180] This allows CHO configurations 3 and 4 to be processed in the UE as soon as it is connected to the new serving cell gNB1, thus avoiding delays in the execution of subsequent CHOs caused by the necessary preparation of new CHO configurations in the new serving cell gNB1.

[0181] CHO configurations 3 and 4 are gNB1-related CHO configurations of subset B. As described above, the UE may evaluate the execution conditions of gNB1-related CHO configurations 3 and 4 to determine whether some execution conditions are met. Also, the UE does not process CHO configurations that do not refer to the serving cell gNB1.

[0182] As can be seen from Figure 20, the execution conditions for gNB2 CHO configuration 4 (see the above table) shall be met and the UE shall perform the CHO procedure with the candidate target gNB2. The CHO procedure may be performed based on the configuration parameters of CHO configuration 4 corresponding to gNB2.

[0183] Similarly, upon successful completion of CHO to gNB2, the UE again maintains multiple CHO configurations 1 to 6. As a result, CHO configurations 5 and 6 are immediately available to the UE for processing upon connecting to the new serving cell gNB2.

[0184] The improved CHO procedure may then be further continued in the same manner. Although not shown in Figure 20, the UE may perform another CHO procedure for gNB0 or gNB1, etc.

[0185] According to one implementation example, the following ASN1 definition defines signaling that source gNB0 can use to inform UEs about candidates included in subsets such as gNB1 and gNB2 of subset A. [Table 10] This allows one candidate target cell to be identified by its physical cell ID and ARFCN value (see bold and underlined text above). Thus, to define a subset of two candidate target cells (e.g., subset A), source gNB0 may make two transmissions for the candidate target cells, each transmission including the corresponding physical cell ID and ARFCN that identify the two candidate target cells (e.g., gNB1 and gNB2 for subset A).

[0186] In the above description of the improved CHO procedure, it was simply assumed that the UE knows which CHO configuration to use upon successful completion of the CHO procedure to a new serving cell. The following exemplary embodiment of the improved CHO procedure provides some details on how the UE determines the appropriate CHO configuration to use. According to a first implementation, the UE determines the appropriate CHO configuration based on the current serving cell. Thus, each CHO configuration can be associated with the cell for which it should be used. For example, CHO configurations 1 and 2 above are associated with a cell of gNB0, CHO configurations 3 and 4 above are associated with a cell of gNB1, and CHO configurations 5 and 6 above are associated with a cell of gNB2. Thus, the UE can determine the CHO configuration associated with the current serving cell when connecting to a new serving cell. According to a similar embodiment, the UE determines the appropriate CHO configuration as belonging to the subset associated with the current serving cell. This first implementation has the advantage that no further signaling exchange is required between the base station and the UE for determining the appropriate CHO configuration.

[0187] According to a second implementation, the CHO configuration used by the UE can be controlled by the new serving cell. In response, the new serving cell can send a notification to the UE indicating the CHO configuration used by the UE. For example, the notification can identify several CHO configurations separately (e.g., gNB1 identifies CHO configurations 3 and 4) or can jointly identify a subset of CHO configurations by signaling the subset (e.g., gNB1 identifies subset B). The notification may be sent from the new serving cell to the UE, for example, during the CHO procedure that the UE performs with the new serving cell. The new serving cell can convey the notification to the UE by an appropriate RRC message.

[0188] In conjunction with the above or below implementations, according to another implementation of the improved CHO procedure, a CHO configuration can have an enabled state or a disabled state (also referred to as an enabled state and a disabled state). Accordingly, a CHO configuration in an enabled state is processed by the UE, and a CHO configuration in a disabled state is not processed by the UE. Accordingly, the improved CHO procedure according to this implementation includes appropriately setting the state of the CHO configuration according to the basic concept described above. For example, the UE configures the state of each CHO configuration to either enabled or disabled depending on whether the UE processes the CHO configuration. In the above-described exemplary scenario, when connected to gNB0, the UE sets the states of CHO configurations 1 and 2 to the enabled state and the states of CHO configurations 3, 4, 5, and 6 to the disabled state. Furthermore, when connected to gNB1, the UE sets the states of CHO configurations 3 and 4 to the enabled state and the states of CHO configurations 1, 2, 5, and 6 to the disabled state. The process of setting the CHO configuration state can be performed autonomously by the UE based on the current serving cell (e.g., see the first implementation above), or based on appropriate notification from the current serving cell (e.g., see the second implementation above).

[0189] Also, in combination with the above or below, according to another implementation of the improved CHO procedure, a mechanism is introduced to configure the use of the CHO configuration on a cell-by-cell basis. In particular, the UE receives a cell status notification from the current serving base station (e.g., source base station gNB0), which indicates one or more candidate cells for which the associated CHO configuration is to be enabled or disabled.

[0190] When the UE receives the cell status notification, it can disable or enable the CHO configuration for the notified cell.

[0191] For example, the cell status notification may indicate a disabled cell, in which case the UE disables the CHO configuration associated with that cell. Based on the exemplary CHO configurations 1 to 6 described above, and considering the case where the cell status notification indicates that the cell of gNB2 is to be disabled, CHO configurations 2 and 4 are disabled. Thus, when connected to gNB1, the UE processes only CHO configuration 3 for gNB0, and similarly, when connected to gNB0, the UE processes only CHO configuration 1 for gNB1. As a result, the UE no longer performs CHO for the disabled cell gNB2.

[0192] For example, a cell-specific mechanism may be useful in an example scenario where a previously available candidate target cell is no longer available for a CHO procedure. As an example, it is assumed that gNB2 is no longer available as a target for a CHO procedure for the UE (e.g., due to lack of resources). Therefore, the CHO configuration for this non-long-term available gNB2 no longer needs to be processed by the UE.

[0193] For this purpose, a cell-specific mechanism allows common deactivation of all CHO configurations associated with a cell by providing a cell status notification to the UE.

[0194] Conversely, the cell status notification may also be used to indicate the activation of a cell, for example to activate all (disabled) CHO settings for that cell.

[0195] In the above, it has been simply assumed that the cell status notification is sent to the UE by the UE's current serving cell. Furthermore, some implementation examples provide details regarding the sending of the cell status notification. According to two implementation examples, the cell status notification is carried by a new information element in an RRC message, such as an RRC reconfiguration message, or by a control element in a MAC message.

[0196] Further, in one example variant, the cell status notification is implemented as a bitmap, where each bit of the bitmap corresponds to one candidate target cell, and one value of the bit indicates enabling the CHO setting of the associated candidate target cell, and another value of the bit indicates disabling the CHO setting of the associated candidate target cell.

[0197] The bitmap can be constructed, for example, as follows: [Table 11]

[0198] The above bitmap assumes 32 possible candidate target cells C0 to C31. A value of 1 may indicate that the associated candidate cell is enabled, and a value of 0 may indicate that the associated candidate cell is disabled.

[0199] In the following, different implementation examples of the improved CHO procedure are described, especially with regard to the structure of the multiple CHO configuration: The existing (e.g., Release 16) CHO configuration signaling only supports a maximum of eight candidate cells to be handled by the UE.

[0200] According to a first implementation example, the multiple CHO configurations of the improved CHO procedure are limited to a maximum of eight exemplary CHO configurations. This has the advantage of ensuring backward compatibility because legacy UEs (UEs that do not support the improved CHO configuration) can also process multiple CHO configurations. Then, among the eight CHO configurations, different subsets of CHO configurations to be selectively used by the UE can be defined according to the improved CHO procedure (according to either the implementation described above or below). For example, this implementation example is applied to the above CHO configurations 1 to 6, resulting in three distinct subsets of CHO configurations.

[0201] For legacy UEs, all of the CHO configurations (up to 8 CHO configurations) are processed, taking into account that legacy UEs cannot distinguish between different subsets of CHO configurations.

[0202] According to another second implementation example, since there may be more than eight CHO configurations according to the improved CHO procedure, the improved UE is permitted more than eight CHO configurations, for example, up to 16, 24, or 32 CHO configurations. However, in one example variant, these CHO configurations are configured in a sequence, and only the first eight CHO configurations of the sequence can be used for CHO in the current serving cell. In other words, the creation of multiple CHO configurations is limited so that only a maximum of eight CHO configurations can be created for a subset. For example, if the CHO procedure between the UE and another target cell is successfully completed, the UE can replace the first eight elements of the sequence with the eight CHO configurations applicable in the new serving cell.

[0203] For legacy UEs, all of the first eight CHO configurations are processed correctly. This may be consistent with the existing Release 16 specifications, which require that all stored CHO configurations be evaluated by the UE for CHO. That is, not even a single candidate target cell (and its corresponding stored CHO configuration) can be exempted from being evaluated as a candidate for CHO. The legacy UE does not recognize the remaining CHO configurations after the first eight CHO configurations, and therefore, they are not processed by the legacy UE. According to a further implementation example of the improved CHO procedure according to the first solution, the following can be defined for the new Release 18 in accordance with the 3GPP standard: [Table 12] [Table 13] [Table 14]

[0204] As is evident from the new exemplary definition for 3GPP Release 18 above, a new parameter maxNrofCondCell-r18 is defined to allow a maximum of 32 conditional candidate SPcells.

[0205] Additionally, a new CondReconfigToAddModList is defined, which references this new parameter maxNrofCondCells-r18. Additionally, a new CondReconfigID-r18 is defined, which allows to identify the CHO configuration.

[0206] Accordingly, referring again to the second implementation in which the first 8 CHO configurations are treated as candidates for the current serving cell, the sequence of CHO configurations can be defined, for example, by the new 3GPP Rel.18 definitions mentioned above, in particular the sequence provided by CondReconfigID-r18.

[0207] The above definitions assume that new features will be introduced for 3GPP Release 18, and therefore include the term "r18." However, it should also be noted that new features may be introduced in later 3GPP releases, e.g., Release 19, 20, etc., in which case the above definitions may be re-named using the corresponding terms "r19," "r20," etc., instead of "r18."

[0208] Various implementations of the improved CHO procedure have been described above. In various implementations, the preparation of multiple CHO configurations and the transmission of these multiple CHO configurations to the UE have already been described. In the following, a detailed and exemplary implementation of the improved CHO procedure will be described with respect to how the source gNB prepares multiple CHO configurations according to FIG. 20. This description is based on FIG. 21, which shows exemplary and simplified signaling exchanges between different entities involved in the preparation of multiple CHO configurations according to the improved CHO procedure.

[0209] The signaling diagram in Figure 21 shows certain signal sequences grouped together for clarity and ease of understanding. In particular, the pre-preparation of gNB1-related CHO configuration performed by gNB1 follows the logical order of request and response, but is shown together in the sequence only for clarity. Similarly, the pre-preparation of gNB2-related CHO configuration performed by gNB2 follows the logical order of request and response, but is shown together in the sequence only for clarity. Similarly, the pre-preparation of gNB0-related CHO configuration performed by gNB0 follows the logical order of request and response, but is shown together in the sequence only for clarity. However, the message sequence in Figure 21 can differ while following the logical order of steps.

[0210] The gNB0 to which the UE initially connects shall be responsible for preparing multiple CHO configurations. Thus, the preparation includes preparing the CHO configurations of gNB1 and gNB2 that the UE will use when connected to gNB0. For this purpose, gNB0 sends a CHO Prepare message to gNB1 and receives a CHO ACK message from gNB1 containing gNB1's requested CHO configuration parameters for the potential CHO from gNB0. Similarly, gNB0 sends a CHO Prepare message to gNB2 and receives a CHO ACK message from gNB2 containing gNB2's requested CHO configuration parameters for the potential CHO from gNB0.

[0211] Although not shown in Figure 21, gNB0 may generate a gNB0-related CHO configuration for gNB1 by including the CHO configuration parameters corresponding to gNB1 received from gNB1 and determining appropriate execution conditions. Correspondingly, gNB0 may generate a gNB0-related CHO configuration for gNB2 by including the CHO configuration parameters corresponding to gNB2 received from gNB2 and determining appropriate execution conditions.

[0212] As a result, gNB0 has prepared a CHO configuration in subset A, i.e., a CHO configuration that is processed by the UE when connected to gNB0.

[0213] Furthermore, CHO preparation also includes pre-preparation of CHO for when the UE will be connected to either gNB1 or gNB2 in the future. CHO preparation by gNB1 and gNB2 can each be triggered by a CHO Prepare message sent from gNB0, as described for CHO preparation of subset A above.

[0214] For example, after receiving a CHO Prepare message from gNB0, gNB1 transmits a CHO pre-preparation message to gNB2 and gNB0 to request CHO configuration parameters for CHO from gNB1 to gNB2 and gNB0, respectively. As a result, as is clear from Figure 21, gNB1 receives the requested CHO configuration parameters from gNB2 and gNB0.

[0215] Although not shown in Figure 21, gNB1 may generate a gNB1-related CHO configuration for gNB2 by including the CHO configuration parameters corresponding to gNB2 received from gNB2 and determining appropriate execution conditions. Correspondingly, gNB1 may generate a gNB1-related CHO configuration for gNB0 by determining appropriate execution conditions and including the CHO configuration parameters corresponding to gNB0 received from gNB0.

[0216] The gNB1-related CHO configurations for gNB2 and gNB0 thus generated are sent by gNB1 to gNB0 (gNB0 triggered the pre-preparation). As a result, gNB0 obtains the CHO configurations for subset B, i.e., the CHO configurations that will be processed by the UE when connected to gNB1.

[0217] As described above for the pre-preparation performed by gNB1, corresponding pre-preparation can also be performed by gNB2. For example, after gNB2 receives a CHO preparation message from gNB0, gNB2 transmits CHO pre-preparation messages to gNB0 and gNB1 to request CHO configuration parameters for CHO from gNB2 to gNB0 and gNB1, respectively. In response, gNB2 receives the requested CHO configuration parameters from gNB0 and gNB1, as shown in FIG. 21.

[0218] Although not shown in Figure 21, gNB2 may generate a gNB2-related CHO configuration for gNB0 by including the CHO configuration parameters corresponding to gNB0 received from gNB0 and determining appropriate execution conditions. Correspondingly, gNB2 may generate a gNB2-related CHO configuration for gNB1 by determining appropriate execution conditions and including the CHO configuration parameters corresponding to gNB1 received from gNB2.

[0219] The gNB2-related CHO configurations thus generated for gNB0 and gNB1 are sent by gNB2 to gNB0 (gNB0 triggered the pre-preparation). As a result, gNB0 obtains the CHO configurations for subset C, i.e., the CHO configurations that will be processed by the UE when connected to gNB1.

[0220] Various CHO configurations may be transmitted to the UE for use with different CHOs when located in different cells of gNB0, gNB1, and gNB2.

[0221] In the above implementation example, as described with reference to Figure 21, gNB1-related CHO configurations for gNB0 and gNB2 are transmitted separately, and also gNB0-related CHO configurations for gNB1 are transmitted separately. However, according to a variant of this implementation, one CHO ACK message can carry two or more CHO configurations (e.g., one or more of gNB1-related CHO configurations for gNB0 and gNB2 and gNB0-related CHO configurations for gNB1).

[0222] Similarly, assuming an improved CHO ACK message, gNB2 may send one or more of gNB2-related CHO settings for gNB0 and gNB1 and gNB0-related CHO settings for gNB2 to gNB0 in one CHO ACK message.

[0223] For this purpose, a new parameter (eg, an OCTET string or container) of the conditional configuration may be included in the handover confirmation message from the target node to the source node.

[0224] As an example, according to a 5G compliant implementation, the HANDOVER REQUEST ACKNOWLEDGE message known for example from TS 38.413 v17.0.0 can be adapted as follows:

[0225] Section 9.2.3.5 Confirmation of handover request (TS 38.413 v17.0.0) This message is sent by the target NG-RAN node to inform the AMF about the prepared resources at the target.

[0226] Direction: NG-RAN node → AMF [Table 15] In the above definitions, additional suggested definitions for the Conditional Configuration container are shown in bold and underlined.

[0227] Accordingly, according to this variant, the candidate target cells (whether gNB1 or gNB2) do not immediately respond to the CHO preparation message received from gNB0. Rather, the candidate target cells may wait for the end of their respective CHO pre-preparation procedures before sending all of the generated information together to the requesting gNB0.

[0228] It should be noted that the implementation of the above improved CHO procedure does not depend on whether the UE is connected with dual connectivity or not. In the following, it is assumed as an example that the UE is connected with dual connectivity.

[0229] According to one implementation, a UE is configured with a master cell group (MCG) and multiple secondary cell groups (SCGs), i.e., two or more SCGs. For example, in one 5G compliant embodiment, the UE may be configured with two or more MRDC-SecondaryCellGroupConfig information elements as part of an RRCReconfiguration message (see, e.g., TS 38.331 v17.1.0).

[0230] However, only one of the multiple SCGs is active for the UE at a given time, and the UE connects to one or more cells of the active SCG, while the other SCGs are inactive (also called "deactivated").

[0231] This implementation differs from current 3GPP specifications such as TS 38.331. In current 3GPP specifications, only one SCG can be configured for a UE. In particular, according to the 3GPP specifications, a UE can have two sets of cell group configurations (e.g., one Master Cell Group (MCG) configuration and one Secondary Cell Group (SCG) configuration). Furthermore, one SCG can be in an enabled or disabled state, while the MCG is always in an enabled state. Deactivation can be performed via an RRC message. Conditional PSCell Change (CPC) can be performed as an intra-SN handover or an inter-SN handover.

[0232] According to this implementation, there are at least two different possibilities for how the UE determines which of multiple SCGs is valid. According to a first option, the UE can determine the valid SCG to be the SCG that was first configured for the UE. For example, the UE can be configured with SCGs sequentially, and the first added SCG (if the UE does not yet have an SCG) can be determined to be the valid SCG, even if more SCGs are configured thereafter. Additionally or instead of the first option, according to a second option, the UE determines the valid SCG based on, for example, an explicit notification received from the gNB. This explicit notification can also be used to change the valid SCG from one SCG to another.

[0233] Configuring several SCGs can be useful to save signaling overhead. For example, suppose a UE has two SCGs, i.e., a first active SCG and a second inactive SCG, and the UE wants to perform a CPC procedure using a target cell (PSCell) that is not included in the list of SCells configured for the currently active first SCG. However, the target cell is included in the list of SCells configured for the currently inactive second SCG. Therefore, the CPC procedure activates the second SCG, whose SCG configuration information is already available in the UE. This eliminates the need for the UE to perform a reconfiguration procedure to set up a new second SCG. Furthermore, the first SCG is maintained in the UE and is disabled, so the UE does not need to deconfigure the first SCG.

[0234] According to current 3GPP standards (e.g., TS 38.331), there is an existing IE "scg-State" to indicate whether an SCG is in a disabled state or not. According to a variant of the implementation, this IE can be reused for the case of dual connectivity and multiple SCGs (alternatively, other IEs similar to the above scg-State can be introduced).

[0235] In the following, exemplary details are provided to define how different SCGs can be configured in a UE. As an example, the UE receives configuration information, such as an RRC message, from the current serving cell. New variables can be introduced in the RRC to store the configuration of the additional SCGs.

[0236] The setting information is, for example, - common cell ID of the cells in each cell group, - the common frequency range of the cells of each cell group, and - Common radio resources for cells in each cell group It may include one or more of:

[0237] In yet another example, the configuration information of the SCG may further include a list of candidate cells for evaluation for CHO / CPC / CPA procedures upon activation of the SCG.

[0238] According to a further variant, the UE may, for the disabled SCG: - random access to cells of each SCG, - Radio link measurements for the cells of each SCG, and - Uplink synchronization for each SCG cell Do not perform one or more of the steps in

[0239] In particular, according to current 3GPP specifications, when an SCG is configured for a UE, the UE is to immediately apply the configuration and perform random access, including uplink synchronization, in the PSCell of the SCG. Furthermore, regardless of the SCG state (e.g., enabled or disabled), the UE is to perform RLM measurements for one SCG.

[0240] However, this behavior is disadvantageous when more than one SCG is configured in the UE. One function of having multiple SCGs configured in the UE is to allow conditional configuration to be applied to the UE immediately after a successful handover. Therefore, as described above, the UE does not need to perform these procedures for additional SCGs in a disabled state.

[0241] Rather, the UE simply saves these additional disabled SCG configurations for future use without currently applying them, and these additional disabled SCG configurations are applied as needed.

[0242] It may also be beneficial to introduce a mechanism for distinguishing between different SCG configurations in the UE by introducing several SCG configurations, which allows easy addressing of individual SCG configurations and supports, for example, adding, modifying, removing and / or (disabling) SCG configurations.

[0243] To this end, one option is to identify an SCG configuration based on a combination of the cell ID of the PSCell in each SCG and the identifier of the radio resource used by the cell of each SCG for transmission and reception. For example, this radio resource identifier is an Absolute Radio-Frequency Channel Number (ARFCN). This option therefore allows for the reuse of ID parameters of SCG configurations to identify and distinguish them. However, one disadvantage may arise if two SCG configurations have the same PSCell and the same radio resource identifier but, for example, different SCells or contain different configuration elements, e.g., in the intra-SN configuration. It would be impossible to distinguish between such two configurations. Furthermore, this first option may result in high signaling overhead, since the combination of these two IDs may be very long and may need to be signaled each time an SCG configuration needs to be addressed, for example, for modification, deactivation, or (deactivation).

[0244] According to the second option, a new dedicated SCG identifier can be created to distinguish between multiple SCGs. In this case, the length of the dedicated SCG identifier can be any length necessary to distinguish between the maximum number of SCGs, for example, 5 bits to distinguish between 32 SCGs. The new SCG identifier can be called, for example, scgConfigIdentifier.

[0245] According to a further implementation example, when the UE is configured to perform CPC or CPA, the configuration may include an SCG configuration applicable when the UE determines a suitable candidate cell for handover. The configuration also includes associated execution conditions used to identify whether the candidate is suitable for conditional handover. When the candidate becomes suitable or is triggered, the UE applies the configuration associated with the SCG and performs handover. Considering that there are several SCG configurations, the UE determines which of the several SCG configurations to use when performing handover to the configured candidate cell.

[0246] According to one option, the UE stores information associating each of a plurality of SCGs with a cell, and upon successful completion of a conditional procedure for a candidate target cell, the UE determines, based on the stored information, the SCG associated with the candidate target cell for the completed conditional procedure.

[0247] This allows the UE to identify the SCG configuration that applies to it.

[0248] <Improved CPC procedure> Having provided a detailed description of the improved CHO procedure, an exemplary simplified implementation of the improved conditional cell change (CPC) procedure is described below. The improved CPC procedure is based on the principles described above with respect to the improved CHO procedure and will not be repeated here.

[0249] The improved CPC procedure can be understood as a procedure in which a UE disconnects from a source cell and connects to a candidate target cell (which may be selected from many candidates) when an execution condition is met, i.e., a procedure corresponding to the above-mentioned CHO procedure. The CPC procedure is typically used when a UE is in dual connectivity, for example, when the UE is already configured in a master cell group and a secondary cell group and is connected to at least one primary cell (PCell) in the master cell group and at least one primary cell (PSCell) in the secondary cell group. The improved CPC procedure can be performed by the UE to change the PSCell of the SCG. Accordingly, the source cell and target cell participating in CPC belong to the secondary cell group of the UE in dual connectivity.

[0250] Figure 22 shows an exemplary and simplified implementation of the improved conditional cell change (CPC) procedure, illustrating the exchange of messages between the different participating entities (here UE, gNB0, gNB1, and gNB2) and the steps performed by these entities.

[0251] As is clear from Figure 22, the CPC preparation is significantly different from the corresponding CPC preparation in the prior art, for example, as shown in Figure 11. In particular, the CPC preparation includes the preparation of multiple CPC configurations for possible candidate target cells gNB1 and gNB2. Thus, the multiple CPC configurations may include a CPC configuration that is used when the UE is connected to the source cell gNB0. However, according to the improved CPC procedure, the multiple CPC configurations may also include a CPC configuration that is not currently used by the UE when connected to the source cell gNB0, but that will be used by the UE when connected to another serving cell (e.g., gNB1 or gNB2) in the future.

[0252] In other words, the plurality of CPC configurations comprises different subsets of CPC settings, one subset of CPC settings being immediately used by the UE connecting to the source cell gNB0, however at least one further subset of CPC settings of the plurality of cell configurations is pre-prepared for later use.

[0253] As detailed in the improved CHO procedure, the multiple CPC settings can include the following settings: [Table 16]

[0254] In one example option, the plurality of CPC settings may include the following settings: [Table 17]

[0255] As further apparent from Figure 22, after preparing the multiple CPC configurations, the source gNB0 transmits the same CPC configuration to the UE. The UE continues processing the CPC configurations evaluated by the UE when connected to the current serving cell (here, gNB0). In response, the UE evaluates the execution conditions for CPC configurations 1 and 2 associated with gNB0 and determines whether the execution conditions for any of the CPC configurations are met.

[0256] On the other hand, the UE does not process CPC configurations that do not refer to the current serving cell, i.e., the CPC configurations of other subsets of the multiple CPC configurations, here, subsets B and C. Therefore, the UE does not spend resources and time on processing CPC configurations that do not perform CPC.

[0257] When the execution condition of one evaluated CPC configuration is satisfied, the UE performs a CPC procedure on the corresponding candidate target cell of the satisfied CPC configuration. In the example scenario of Figure 22, the UE performs a CPC procedure with the candidate target gNB1. The CPC procedure may be performed based on the configuration parameters of the CPC configuration corresponding to gNB1.

[0258] A further step in the improved CPC procedure involves maintaining multiple CPC configurations 1 through 6 after CPC is successfully completed with gNB1, so that the multiple CPC configurations are not deleted from the UE's memory at this point. This contrasts with the legacy CPA procedure (e.g., the procedure described in Figure 11), in which the UE releases all CPC configurations upon successful CPC.

[0259] As a result, CPC settings 3 and 4 are immediately available to the UE for processing upon connecting to the new serving cell gNB1, thus avoiding delays for subsequent CPC execution caused by the necessary preparation of new CPC settings in the new serving cell gNB1.

[0260] CPC configurations 3 and 4 are gNB1-related CPC configurations of subset B. As before, the UE can determine whether any of the execution conditions for gNB1-related CPC configurations 3 and 4 are met by evaluating the execution conditions for these configurations. Again, the UE does not process CPC configurations that do not refer to the current serving cell, here the new serving cell gNB1.

[0261] As can be seen from Figure 22, the execution conditions for gNB2 CPC configuration 4 (see the above table) shall be met, and the UE shall perform a CPC procedure with the candidate target gNB2. The CPC procedure may be performed based on the configuration parameters of CPC configuration 4 corresponding to gNB2.

[0262] Similarly, upon successful CPC to gNB2, the UE again maintains multiple CPC configurations 1 to 6. As a result, CPC configurations 5 and 6 are immediately available to the UE for processing when connecting to the new serving cell gNB2.

[0263] The improved CPC procedure then continues in the same manner.

[0264] It should be noted that further improvements and modifications of the improved CPC procedure follow similar principles as the corresponding improvements and modifications of the improved CHO procedure described above, and therefore details regarding the improved CHO procedure have been provided in the above description and will not be repeated here.

[0265] For example, similar to what has been described for the improved CHO procedure, the CPC procedure may be improved in how the UE can determine the appropriate CPC setting to use, for example according to a first implementation (based on the current serving cell) or based on a second implementation (controlled by the new serving cell by sending a notification to the UE).

[0266] Furthermore, similar to the description of the improved CHO procedure, the CPC setting can have an enabled state or a disabled state. Therefore, it is the enabled CPC setting that is processed by the UE, and the disabled CPC setting is not processed by the UE. The CPC procedure can be further improved by enabling the setting of the CPC setting state according to the above concept. The process of setting the CPC setting state is performed by the UE autonomously based on the current serving cell (e.g., see the first implementation above) or based on appropriate notification from the current serving cell (e.g., see the second implementation above). Further details regarding the improved CHO procedure have been provided above and will not be repeated here.

[0267] Furthermore, similar to the description of the improved CHO procedure, the CPC procedure may be further improved by implementing a mechanism for configuring the use of cell-specific CPC settings. In particular, the UE receives a cell status notification from the current serving base station (e.g., source base station gNB0), where the cell status notification indicates one or more candidate cells for which the associated CPC settings are to be enabled or disabled. Upon receiving the cell status notification, the UE may disable or enable the CPC settings for the notified cells. Furthermore, reference is made to the description of the improved CHO procedure above, particularly regarding details of how to implement the cell status notification, which also apply to the cell status notification in the improved CPC procedure, including the use of a new IE in an RRC message or a CE in a MAC message, and the use of a bitmap. Further details regarding the improved CHO procedure have been provided above and will not be repeated here.

[0268] Additionally, similar to that described for the improved CHO procedure, the CPC procedure may be further improved by allowing multiple CPC configurations, limited to a maximum of eight. Alternatively, there may be more than eight CPC configurations, in which case only the first eight CPC configurations in the sequence may be used for CPC in the current serving cell. Further details regarding the improved CHO procedure are provided above and will not be repeated here.

[0269] Additionally, similar to that described for the improved CHO procedure, the CPC procedure may include corresponding exchanges of preparation messages and pre-preparation messages between various gNBs for preparation of multiple CPC configurations. Details are as described above for the CHO procedure using FIG. 21 and are conceptually applicable to the improved CPC procedure as well. Details for the improved CHO procedure are described above in connection with FIG. 21 and will not be repeated here. However, in brief, the improved CPC procedure may include preparation of gNB0-related CPC configurations by gNB0's current serving cell based on CPC configuration parameters obtained from gNB1 and gNB2, respectively, and based on execution conditions determined by gNB0.

[0270] Furthermore, the improved CPC procedure may include, in gNB1, prior preparation of gNB1-related CPC configurations for gNB2 and gNB0, triggered, for example, by a CPC preparation message from gNB0. Furthermore, the improved CPC procedure may include, in gNB2, prior preparation of gNB2-related CPC configurations for gNB1 and gNB0, triggered, for example, by a CPC preparation message from gNB0. The gNB1-related CPC configurations for gNB2 and gNB0 thus generated and the gNB2-related CPC configurations for gNB0 and gNB1 thus generated are transmitted by gNB1 and gNB2 to gNB0, respectively. As a result, gNB0 obtains CPC configurations for subsets B and C.

[0271] Various CPC settings can be transmitted to the UE and used with different CPCs when located in different cells of gNB0, gNB1, and gNB2, as described with reference to FIG. 22.

[0272] Furthermore, similar to the description of the improved CHO procedure, the CPC procedure can also benefit from the configuration of multiple SCGs. The description of the improved CHO procedure above already applies to the improved CPC procedure as well, so how different SCGs are configured and enabled (or disabled) will not be repeated here. Similarly, how a UE determines which SCG is enabled among multiple SCGs has already been described for the improved CHO procedure, and the same applies to the improved CPC procedure, so it will not be repeated here. Furthermore, as already described for the improved CHO procedure, the fact that a UE does not need to perform a specific procedure (e.g., random access) for a disabled SCG has already been described for the improved CHO procedure, and the same applies to the improved CPC procedure, so it will not be repeated here. How multiple SCGs can be distinguished has been described in detail for the improved CHO procedure above (see the combination of PSCell ID+ARFCN or a new dedicated SCG ID), and the same applies to the improved CPC procedure, so it will not be repeated here. Furthermore, for the improved CHO procedure, details of the association of a candidate cell with an SCG to activate the SCG when the UE performs a handover to the candidate cell have been provided above and apply similarly to the improved CPC procedure, so will not be repeated here.

[0273] According to another implementation example, the subset concept introduced for the improved CPC procedure can be considered together with the SCG concept of dual connectivity. The subset function and the SCG function are both grouping concepts for grouping different cells. In one example, the subset can correspond to the potential SCG of a UE.

[0274] Furthermore, given the possibility of having multiple SCGs, multiple subsets are also considered as multiple SCGs.

[0275] For example, referring to Figure 22, subset B consists of CPC configurations for gNB0 and gNB2. The potential SCG for a UE when connected to gNB1 may include the same cells, i.e., gNB0 and gNB2.

[0276] <Improved CPA Procedure> Having provided a detailed description of the improved CHO and CPC procedures, we now describe an exemplary and simplified implementation of an improved conditional cell addition (CPA) procedure. The improved CPA procedure is based on the principles described with respect to the improved CHO procedure above and therefore will not be repeated here.

[0277] The improved CPA procedure can be understood as a procedure in which, if an execution condition is met, a UE connects to a candidate target cell (which may be selected from many candidates), and the candidate target cell becomes a primary cell of the UE's secondary cell group that is different from the UE's master cell group. The CPA procedure is typically used when a UE enters dual connectivity, for example, in the process of setting up a secondary cell group and connecting to a primary cell (PSCell) of the secondary cell group. CPA can also be used to add more SCells to an SCG or to create another SCG with another PSCell, but this other SCG is initially in a disabled state.

[0278] Furthermore, CPA does not result in a change in the UE connection with the master node (here, gNB0), but rather, based on CPA, the UE connection with a secondary node (SN) can be connected or disconnected. Accordingly, the following description exemplarily assumes that gNB0 is the master node and gNB1 and gNB2 are potential secondary nodes to be added via the improved CPA procedure.

[0279] Figure 23 shows an exemplary and simplified implementation of such an improved conditional cell addition (CPA) procedure, illustrating the exchange of messages between the different participating entities (here UE, gNB0, gNB1, and gNB2) and the steps performed by these entities.

[0280] As is clear from Figure 23, the CPA preparation is significantly different from the corresponding CPA preparation in the prior art, for example, as shown in Figure 12. In particular, the CPA creation includes the creation of multiple CPA configurations for possible candidate target cells gNB1 and gNB2. Thus, the multiple CPA configurations may include a CPA configuration that is used when the UE is connected to the source cell gNB0. However, according to the improved CPA procedure, the multiple CPA configurations may also include a CPA configuration that is not currently used when the UE is connected to the source cell gNB0, but that will be used when the UE is additionally connected to another serving cell (e.g., gNB1 or gNB2) in the future.

[0281] In other words, the multiple CPA configurations include different subsets of CPA configurations, where one subset of CPA configurations is to be immediately used by the UE connecting to the source cell gNB0, but a subset of CPA configurations of at least one of the multiple cell configurations is prepared in advance for later use.

[0282] As detailed in the improved CHO procedure, multiple CPA settings include the following settings: [Table 18]

[0283] As an example, the plurality of CPA settings include the following settings: [Table 19]

[0284] As further apparent from Figure 23, after preparing the multiple CPA configurations, the source gNB transmits the same CPA configuration to the UE. The UE continues the CPA configuration process that is evaluated by the UE when connected to the current serving cell (here, gNB0). In response, the UE evaluates the execution conditions for CPA configurations 1 and 2 related to gNB0 and determines whether some of the execution conditions for the CPA configurations are satisfied.

[0285] On the other hand, the UE does not process CPA configurations that do not refer to the current serving cell, i.e., CPA configurations of other subsets of the multiple CPA configurations, here, subsets B and C. Therefore, the UE does not spend resources and time processing CPA configurations that do not perform CPA.

[0286] When the execution condition of one evaluated CPA configuration is satisfied, the UE performs a CPA procedure with the corresponding candidate target cell of the satisfied CPA configuration. In the example scenario of Figure 23, the UE performs a CPA procedure with the candidate target gNB1 to generate a new SCG with the target gNB1 as a PSCell. The CPA procedure may be performed based on the configuration parameters of the CPA configuration corresponding to gNB1.

[0287] A further step in the improved CPA procedure includes maintaining multiple CPA configurations 1-6 when CPA is successfully completed for gNB1. Therefore, the multiple CPA configurations are not deleted from the UE memory at this point. This is in contrast to the legacy CPA procedure (e.g., the procedure described in FIG. 12), in which the UE releases all CPA configurations upon successful CPA.

[0288] As a result, CPA configurations 3 and 4 are immediately available for processing in the UE when connecting to the new serving cell gNB1, thus avoiding delays for subsequent CPA executions caused by the necessary preparation of new CPA configurations in the new serving cell gNB1.

[0289] CPA configurations 3 and 4 are gNB1-related CPA configurations of subset B. As described above, the UE can determine whether any of the execution conditions is met by evaluating the execution conditions of gNB1-related CPA configurations 3 and 4. In addition, the UE does not process CPA configurations that do not reference the current serving cell, in this case, the new serving cell gNB1.

[0290] As can be seen from Figure 23, it is exemplarily assumed that the execution conditions for gNB2 CPA configuration 4 (see the table above) are met, and the UE creates another SCG with gNB2 as the PSCell by performing another CPA procedure with candidate target gNB2. The CPA procedure may be performed based on the configuration parameters of CPA configuration 4 corresponding to gNB2.

[0291] Similarly, upon successful CPA with gNB2, the UE again maintains multiple CPA configurations 1 to 6. As a result, CPA configurations 5 and 6 become immediately available to the UE for processing by the UE when connecting to the new serving cell gNB2.

[0292] The improved CPA procedure may then proceed further in the same manner.

[0293] Further improvements and modifications of the improved CPA procedure follow similar principles as the corresponding improvements and modifications of the improved CHO procedure described above. Accordingly, details regarding the improved CHO procedure have been provided in the above description and will not be repeated here.

[0294] For example, similar to what has been described for the improved CHO procedure, the CPA procedure may be improved in how the UE can determine the appropriate CPA setting to use, for example, according to a first implementation (based on the current serving cell) or based on a second implementation (controlled by the new serving cell by sending a notification to the UE).

[0295] Furthermore, similar to the description of the improved CHO procedure, the CPA configuration can have an enabled or disabled state. Accordingly, the enabled CPA configuration is processed by the UE, and the disabled CPA configuration is not processed by the UE. The CPA procedure can be further improved by enabling the setting of the CPA configuration state according to the above concept. The process of setting the CPA configuration state can be performed by the UE autonomously based on the current serving cell (e.g., see the first implementation above), or based on an appropriate notification from the current serving cell (e.g., see the second implementation above). Further details regarding the improved CHO procedure have been provided above and will not be repeated here.

[0296] Furthermore, similar to the description of the improved CHO procedure, the CPA procedure may be further improved by implementing a mechanism for configuring the use of the CPA configuration for each individual cell. In particular, the UE receives a cell status notification from the current serving base station (e.g., source base station gNB0), where the cell status notification indicates one or more candidate cells for which the associated CPA configuration should be enabled or disabled. Upon receiving the cell status notification, the UE may disable or enable the CPA configuration for the indicated cell. Furthermore, as described above for the improved CHO procedure, the details of how the cell status notification is implemented also apply to the cell status notification in the improved CPA procedure, including the use of a new IE in an RRC message or a CE in a MAC message, the use of a bitmap, etc. Further details regarding the improved CHO procedure have been provided above and will not be repeated here.

[0297] Additionally, similar to that described for the improved CHO procedure, the CPA procedure can be further improved by limiting the number of CPA configurations to a maximum of eight. Alternatively, if there are more than eight CPA configurations, only the first eight CPA configurations in the sequence may be used for CPA in the current serving cell. Further details regarding the improved CHO procedure are provided above and will not be repeated here.

[0298] Additionally, similar to that described for the improved CHO procedure, the CPA procedure may include corresponding exchanges of preparation messages and pre-preparation messages between various gNBs for preparation of multiple CPA configurations. Details are described above with respect to the CHO procedure using FIG. 21, but are conceptually applicable to the improved CPA procedure as well. Details regarding the improved CHO procedure are described above in connection with FIG. 21 and will not be repeated here. However, in brief, the improved CPA procedure may include preparation of a gNB0-related CPA configuration by gNB0's current serving cell based on CPA configuration parameters obtained from gNB1 and gNB2, respectively, and based on execution conditions determined by gNB0.

[0299] Furthermore, the improved CPA procedure may include, in gNB1, advance preparation of gNB1-related CPA configurations for gNB2 and gNB0, triggered, for example, by a CPA preparation message from gNB0. Furthermore, the improved CPA procedure may include, in gNB2, advance preparation of gNB2-related CPA configurations for gNB1 and gNB0, triggered, for example, by a CPA preparation message from gNB0. The gNB1-related CPA configurations for gNB2 and gNB0 thus generated and the gNB2-related CPA configurations for gNB0 and gNB1 thus generated are transmitted by gNB1 and gNB2, respectively, to gNB0. As a result, gNB0 obtains CPA configurations for subsets B and C.

[0300] As described with reference to FIG. 23, various CPA configurations may be transmitted to the UE for use with different CPAs when located in different cells of gNB0, gNB1, and gNB2.

[0301] Furthermore, similar to the description of the improved CHO procedure, the CPA procedure can also benefit from the configuration of multiple SCGs. How to configure and activate (deactivate) different SCGs has already been described for the improved CHO procedure, as described above, and applies similarly to the improved CPA procedure, so it will not be repeated here. Similarly, how a UE determines which SCG is active among multiple SCGs has already been described for the improved CHO procedure, as described above, and applies similarly to the improved CPA procedure, so it will not be repeated here. Furthermore, the fact that a UE does not need to perform a specific procedure (e.g., random access) for a deactivated SCG has already been described for the improved CHO procedure, as described above, and applies similarly to the improved CPA procedure, so it will not be repeated here. How multiple SCGs can be distinguished has been described in detail for the improved CHO procedure (see the combination of PSCell ID+ARFCN or a new dedicated SCG ID), as described above, and applies similarly to the improved CPA procedure, so it will not be repeated here. Furthermore, when a UE performs a handover to a candidate cell, the details of associating the candidate cell with the SCG to activate the SCG are the same as those described for the improved CHO procedure above, and apply similarly to the improved CPA procedure, so they will not be repeated here.

[0302] <Second solution> Figure 24 shows a simplified UE structure according to an example implementation of the improved mobility procedure of the second solution, which can be implemented based on the general UE structure described in relation to Figure 13. The various structural elements of the UE shown in Figure 24 can be connected to each other, for example, by corresponding input / output nodes (not shown) for exchanging control data, user data, and other signals. Although not shown for illustrative purposes, the UE may include further structural elements.

[0303] As can be seen from FIG. 24, the UE may include a cell configuration receiving unit (for receiving a plurality of cell configurations including cell configuration parameters and execution conditions), an execution condition evaluation circuit, a conditional cell mobility procedure circuit, and a cell configuration processing circuit.

[0304] In this case, the receiver of the UE may be configured to at least partially perform one or more of the following, for example receiving the cell configuration.

[0305] As will become apparent from the present disclosure, the processing circuitry of the UE may be configured to at least partially perform one or more of, for example, performing a conditional cell mobility procedure if an enabling condition is met, evaluating an enabling condition, storing a cell pre-configuration, releasing a previous cell configuration, etc.

[0306] In this case, as will become apparent from the present disclosure, the transmitter of the UE may be configured to at least partially perform one or more of the following, for example, sending measurement reports to the UE's serving cell.

[0307] As will be described in further detail below, the procedure disclosed as an example in the present disclosure is performed by a UE comprising: a receiver unit of the UE receives a first set of one or more cell configurations; each cell configuration includes cell configuration parameters for performing a conditional cell mobility procedure for each candidate target cell, and includes an execution condition for when to perform the conditional cell mobility procedure for each candidate target cell; at least one cell configuration for each candidate target cell includes a cell pre-configuration for another candidate target cell different from each candidate target cell, the cell pre-configuration including cell configuration parameters for performing the conditional cell mobility procedure for the other candidate target cell, to be used by the UE when connected to each candidate target cell; a circuit in the UE evaluates the execution condition of the first set of cell configurations; and, if the execution condition is met for each candidate target cell in the first set of cell configurations, the circuit performs the conditional cell mobility procedure for each candidate target cell based on the cell configuration parameters of each candidate target cell. Upon successful completion of the conditional cell mobility procedure, the circuit, in operation, storing the cell pre-configuration of the other candidate target cell as the cell configuration of the other candidate target cell; Release the first set of stored cell settings; Evaluate the newly stored cell configuration execution conditions of other candidate target cells. A corresponding exemplary method is performed by the UE receiving a first set of one or more cell configurations; each cell configuration includes cell configuration parameters for performing a conditional cell mobility procedure for each candidate target cell and an execution condition regarding when to perform the conditional cell mobility procedure for each candidate target cell; At least one cell configuration of each candidate target cell includes a cell preconfiguration of another candidate target cell different from each candidate target cell, and the cell preconfiguration includes cell configuration parameters for performing a conditional cell mobility procedure to the other candidate target cell, which are used by the UE when the UE is connected to each candidate target cell; receiving the signal; evaluating a first set of execution conditions for the cell configuration; performing, for each candidate target cell of a first set of cell configurations, the conditional cell mobility procedure based on cell configuration parameters of each candidate target cell if an execution condition is met for that candidate target cell; If the conditional cell mobility procedure is successfully completed, storing the cell pre-configuration of the other candidate target cell as a cell configuration of the other candidate target cell; clearing a first set of stored cell configurations; Evaluating the execution conditions of the newly stored cell configuration of other candidate target cells.

[0308] FIG. 25 shows a sequence diagram corresponding to an example of the UE and its behavior in accordance with the UE method described above.

[0309] In this way, the above-mentioned improved mobility procedure achieves the objectives and overcomes some of the drawbacks mentioned above. For example, the improved mobility procedure of the second solution involves the UE having multiple cell configurations, including pre-prepared cell configurations of other candidate cells. Accordingly, cell configurations for potential future conditional cell mobility procedures to other candidate cells are already available to the UE before performing this conditional cell mobility procedure and can be used by the UE immediately upon successful completion of the conditional cell mobility procedure. In this way, the improved mobility procedure can expedite subsequent conditional cell mobility procedures.

[0310] In some exemplary embodiments, the improved mobility procedure includes, among other things, an improved source base station to which the UE is currently connected (e.g., referred to as the serving base station because it serves the UE) and an improved target base station that is the target of the conditional cell mobility procedure. Accordingly, the improved mobility procedure also provides improved base stations that participate in the mobility procedure, as described below.

[0311] Figure 26 shows a simplified exemplary source base station structure according to one implementation example of the improved mobility procedure, which can be implemented based on the general base station structure described in relation to Figure 13. The various structural elements of the source base station shown in Figure 26 can be connected to each other, for example, by corresponding input / output nodes (not shown) for exchanging control and user data and other signals. Although not shown for illustrative purposes, the source base station may include additional structural elements.

[0312] Thus, the source base station includes a cell setting transmitter (cell setting includes cell setting parameters and execution conditions) and a cell setting preparation circuit.

[0313] In this case, as will become apparent from the present disclosure, the receiver of the source base station can be exemplarily configured to at least partially perform one or more of receiving requested cell configuration parameters, receiving cell configurations of other candidate target cells, etc.

[0314] In this case, as will become apparent from the present disclosure, the processing circuitry of the source base station may be configured to at least partially perform one or more of, for example, determining cell configuration parameters, generating the cell configuration, and the like.

[0315] In this case, as will become apparent from the present disclosure, the transmitter of the source base station may be configured to at least partially perform one or more of, for example, sending a cell configuration to the UE, sending a request to a candidate target cell requesting cell configuration parameters, etc.

[0316] An example procedure, as disclosed in more detail below, is performed by a source base station comprising: circuitry in the source base station generates a first set of one or more cell configurations; each cell configuration includes cell configuration parameters for performing a conditional cell mobility procedure for each candidate target cell and includes an execution condition for when to perform the conditional cell mobility procedure for each candidate target cell; at least one cell configuration for each candidate target cell includes a cell pre-configuration for another candidate target cell different from each candidate target cell; the cell pre-configuration includes cell configuration parameters for performing the conditional cell mobility procedure for the other candidate target cell, to be used by the UE when the UE is connected to each candidate target cell; and a transmitter unit in the source base station transmits the generated first set of one or more cell configurations to the UE.

[0317] The corresponding method is performed by a source base station. generating a first set of one or more cell configurations; each cell configuration includes cell configuration parameters for performing a conditional cell mobility procedure for each candidate target cell and an execution condition regarding when to perform the conditional cell mobility procedure for each candidate target cell; At least one cell configuration of each candidate target cell includes a cell preconfiguration of another candidate target cell different from each candidate target cell, and the cell preconfiguration includes cell configuration parameters for performing a conditional cell mobility procedure to the other candidate target cell, which are used by the UE when the UE is connected to each candidate target cell; generating a transmitting the generated first set of one or more cell configurations to the UE; Includes:

[0318] A sequence diagram corresponding to an example source base station behavior in accordance with the source base station and corresponding method described above is shown in Figure 27. The sequence diagram illustrates an example simplified implementation of the source base station method described above.

[0319] As explained in detail for the first solution based on Figures 18 and 19, the target base station may also participate in the second solution, so details regarding the behavior of the target base station will not be repeated here.

[0320] As is apparent from the above description, the improved UE, improved source base station, and improved target base station achieve the objectives, overcome some of the identified problems, and achieve advantages by participating in the improved mobility procedure.

[0321] In accordance with the second solution, an improved mobility procedure involving the above-mentioned improved devices is described below.

[0322] As already assumed in the first solution, the improved mobility procedure of the second solution is exemplarily assumed to be an improved conditional handover procedure (improved CHO procedure). However, this assumption of CHO as an improved conditional cell mobility procedure does not mean that the improved mobility procedure should be limited to conditional handover. Rather, the principles underlying the improved mobility procedure are also applicable to other conditional cell mobility procedures, such as a conditional cell change procedure (e.g., see CPC above) and a conditional cell addition procedure (e.g., see CPA above).

[0323] Figure 28 is a signaling diagram showing a simplified implementation of an example of an improved CHO procedure relating to the second solution, illustrating the exchange of messages between the different participating entities (here UE, gNB0, gNB1, and gNB2) and the steps performed by these entities.

[0324] Assume that the UE is currently connected to the source gNB. According to the improved CHO procedure, however, the preparation of the CHO by the source gNB is significantly different from the corresponding CHO preparation in the prior art, as shown in Figures 9 and 10. Furthermore, the CHO preparation of the second solution has many commonalities with the CHO preparation of the first solution, but also has differences, as will become clear below.

[0325] Similar to the CHO preparation in the first solution, the CHO preparation in the second solution also involves the preparation of multiple CHO configurations for possible candidate target cells gNB1 and gNB2. Therefore, the multiple CHO configurations may include a CHO configuration to be used by the UE when the UE is connected to the source cell gNB0. However, according to the improved CHO procedure of the second solution, the multiple CHO configurations may also include a CHO configuration that the UE does not currently use when connected to the source cell gNB0, but will use when connected to another serving cell (e.g., gNB1 or gNB2) in the future.

[0326] However, the first solution is based on providing different CHO configurations to different subsets, whereas the second solution relies on the concept of incorporating CHO pre-configurations that the UE may use in the future into the CHO configuration that the UE currently uses.

[0327] For example, for the second solution, as already described in detail for the first solution above, the multiple CHO configurations initially prepared by the serving gNB0 may include the following: [Table 20]

[0328] As an example, a multiple CHO configuration includes: [Table 21]

[0329] Thus, the serving cell prepares all necessary CHO configurations for use by the UE, including the CHO configuration that is currently used when the UE is connected to the source cell, and the CHO configuration that will be used later when the UE is connected to another cell (gNB1 or gNB2).

[0330] According to one example, the source gNB0 may prepare the above-described multiple CHO configurations corresponding to those described in FIG. 21 with respect to the first solution. Accordingly, the improved CHO procedure of the second solution may involve the exchange of preparation messages and pre-preparation messages between various gNBs for the preparation of the multiple CHO configurations. Although details have been described with respect to the CHO procedure of the first solution using FIG. 21, they may also conceptually apply to the improved CHO procedure of the second solution. Details of the improved CHO procedure have been described above with reference to FIG. 21 and will not be repeated here. However, in brief, the improved CHO procedure according to the second solution may include the preparation of a gNB0-related CHO configuration by the gNB0's current serving cell based on CHO configuration parameters obtained from gNB1 and gNB2, respectively, and based on an execution condition determined by gNB0.

[0331] Furthermore, the improved CHO procedure of the second solution means may include, in gNB1, advance preparation of gNB1-related CHO configuration for gNB2 and gNB0, such as triggered by a CHO preparation message from gNB0. Furthermore, the improved CHO procedure of the second solution means may include, in gNB2, advance preparation of gNB2-related CHO configuration for gNB1 and gNB0, such as triggered by a CHO preparation message from gNB0. The gNB1-related CHO configuration for gNB2 and gNB0 thus generated and the gNB2-related CHO configuration for gNB0 and gNB1 thus generated are transmitted by gNB1 and gNB2 to gNB0, respectively. As a result, gNB0 acquires the CHO configuration.

[0332] However, unlike the first solution, the serving cell does not separately transmit the obtained CHO configuration to the UE. Instead, according to the second solution, the source base station prepares a CHO configuration for gNB1, which not only includes configuration parameters and execution conditions for CHO for gNB1 (see CHO configuration 1 above), but also includes gNB1-related CHO pre-configurations for gNB0 and gNB2 (i.e., when the UE is connected to gNB1, see CHO configurations 3 and 4 above). The CHO configuration for gNB1 obtained in this way is extended by the CHO pre-configuration (CHO for gNB1 in this example) that the UE uses when performing the CHO configuration.

[0333] Similarly, the CHO configuration for gNB2 not only includes the configuration parameters and execution conditions for CHO for gNB2 (see CHO configuration 2 above), but also includes gNB2-related CHO pre-configurations for gNB0 and gNB1 (i.e., when the UE is connected to gNB2, see CHO configurations 5 and 6 above).

[0334] For this purpose, the serving cell gNB0 sends two extended CHO configurations for gNB1 and gNB2 to the UE.

[0335] As can be seen from Figure 28, after the preparation of the two extended CHO configurations and their transmission to the UE, the UE will process the two extended CHO configurations for a potential CHO procedure. In response, the UE evaluates the execution conditions of gNB0-related CHO configurations 1 and 2 to determine whether some of the execution conditions for the CHO configurations are met. gNB1-related CHO configurations 3 and 4 and gNB2-related CHO configurations 5 and 6 are stored in the gNB0-related CHO configuration, but are not processed by the UE.

[0336] When the execution condition of one evaluated CHO configuration is satisfied, the UE performs the CHO procedure with the corresponding candidate target cell of the satisfied CHO configuration. In the example scenario of Figure 28, it is assumed that the UE performs the CHO procedure with the candidate target gNB1.

[0337] The CHO procedure may be performed based on the configuration parameters of the CHO configuration corresponding to gNB1. Thus, the UE applies the CHO configuration for gNB1, and thereby additionally adopts the gNB1-related CHO pre-configurations for gNB2 and gNB0 as the CHO configuration to be processed now upon connection with the new serving cell gNB1.

[0338] This makes CHO configurations 3 and 4 available for processing in the UE as soon as it connects to the new serving cell gNB1. Thus, delays in the execution of subsequent CHOs caused by the necessary preparation of new CHO configurations in the new serving cell gNB1 are avoided. Furthermore, the signaling overhead for the UE in the new serving cell is reduced, as the new serving cell gNB1 does not need to send gNB1-related CHO configurations to the UE.

[0339] In one aspect of this second solution, after a successful CHO to gNB1, the UE may release previously stored CHO settings, considering these no longer necessary.

[0340] As before, the UE may proceed with the CHO procedure in gNB1 evaluating the execution conditions of gNB1-related CHO configurations 3 and 4 to determine whether any execution conditions are met.

[0341] Although not shown in Figure 28, the UE may perform another CHO procedure with gNB0 or gNB2.

[0342] Further Aspects According to a first aspect, there is provided a user equipment comprising: a receiver unit receiving a plurality of cell configurations from a source base station, each cell configuration including cell configuration parameters for performing a conditional cell mobility procedure for a respective candidate target cell and including an execution condition for when to perform the conditional cell mobility procedure; the plurality of cell configurations including a first subset of cell configurations to be evaluated by the UE when connected to the source base station; and the plurality of cell configurations including a second subset of cell configurations to be evaluated by the UE when connected to a first candidate target cell of the plurality of candidate target cells, the first candidate target cell being different from the source cell of the source base station; and circuitry in the UE evaluating the execution condition for only the first subset of cell configurations.

[0343] According to a second aspect provided in addition to the first aspect, the circuitry includes, upon successful completion of a conditional cell mobility procedure between the UE and a first candidate target cell, Maintaining multiple received cell configurations; Evaluate the execution conditions for only the second subset of cell settings.

[0344] In one optional implementation, the circuit comprises: If each subset of cell configurations is associated with one cell, based on the cell to which the UE is currently connected, based on a notification received from a first candidate target cell indicating a subset of cell configurations to be evaluated by the UE; A second subset of cell configurations to be evaluated is determined.

[0345] According to a third aspect provided in addition to the first or second aspect, evaluating only the first subset of cell settings includes the circuit not evaluating execution conditions of remaining cell settings of the plurality of candidate target cells that do not belong to the first subset of cell settings.

[0346] According to a fourth aspect provided in addition to any one of the first to third aspects, the plurality of cell configurations includes more than x cell configurations. In one optional implementation, the plurality of cell configurations is configured as a sequence of cell configurations. A first subset of the cell configurations includes the first x element cell configurations in the sequence. In a further optional implementation, the number x is 8.

[0347] According to a fifth aspect provided in addition to any one of the first to third aspects, the plurality of cell configurations includes x cell configurations, and the first subset of cell configurations is less than x cell configurations. In one optional implementation, the number x is 8.

[0348] According to a sixth aspect, the cell configurations belonging to the first subset are associated with an enabled state, and the remaining cell configurations of the plurality of cell configurations that do not belong to the first subset are associated with a disabled state. In one optional implementation, the cell configurations associated with the disabled state are not evaluated by the UE when performing the conditional cell mobility procedure, and the cell configurations associated with the enabled state are evaluated by the UE when performing the conditional cell mobility procedure.

[0349] In a seventh aspect provided in addition to any one of the first to sixth aspects, the plurality of cell configurations includes two or more cell configurations associated with one candidate target cell. In one optional implementation, the first subset includes one or more cell configurations but does not include all of the plurality of cell configurations. In a further optional implementation, the cell configurations in the first subset are each configurations of different candidate target cells. In one optional implementation, the plurality of cell configurations includes one subset of cell configurations for each cell configuration in the first subset.

[0350] According to an eighth aspect provided in addition to any one of the first to seventh aspects, a receiving unit receives a cell status notification from a source base station, the cell status notification comprising: indicating one or more candidate cells for which the associated cell configuration is to be enabled or disabled; Optionally, cell state notification can be carried in a Radio Resource Control (RRC) message, or · Carried in the control element of a Medium Access Control (MAC) message.

[0351] In one optional implementation, the cell status notification is a bitmap, each bit of the bitmap corresponding to one candidate target cell among a plurality of candidate target cells, one value of the bit indicating enabling cell configuration of the corresponding candidate target cell, and another value of the bit indicating disabling cell configuration of the corresponding candidate target cell.

[0352] According to a ninth aspect provided in addition to the first to eighth aspects, the conditional cell mobility procedure comprises: a conditional handover, where if the execution condition is met, the UE is disconnected from the source cell and connected to a candidate target cell, optionally the source cell and the target cell belonging to the same master cell group of the UE; a conditional cell change, where if an execution condition is met, the UE is disconnected from the source cell and connected to a candidate target cell, the source cell and the candidate target cell belonging to a secondary cell group of the UE that is different from a master cell group of the UE; and A conditional cell addition, in which the UE connects to a candidate target cell if an execution condition is met, and the candidate target cell is a primary cell of a secondary cell group of the UE that is different from a master cell group of the UE. It is one of the following.

[0353] According to a tenth aspect provided in addition to any one of the first to ninth aspects, a cell configuration parameter of the cell configuration is radio resource configuration of said candidate target cells, such as resource block and physical channel configuration; security configuration of said candidate target cells; Dual connectivity information such as master cell group information, secondary cell group information, etc. a measurement configuration of said candidate target cells; Mobility settings, Contains one or more of:

[0354] In one optional implementation, the execution condition for when to perform the conditional cell mobility procedure comprises one or more sub-conditions, and the execution condition is fulfilled by one or all of the one or more sub-conditions being fulfilled. As a further option, the sub-conditions relate to one or more communication qualities of the source cell and the candidate target cells that relate to the execution condition.

[0355] According to an eleventh aspect provided in addition to any one of the first to tenth aspects, each cell configuration of the first subset includes a cell configuration parameter and an execution condition for performing a conditional cell mobility procedure from the source cell to each candidate target cell, and each cell configuration of the second subset includes a cell configuration parameter and an execution condition for performing a conditional cell mobility procedure from the first candidate target cell to each candidate target cell.

[0356] According to a twelfth aspect provided in addition to any one of the first to eleventh aspects, a UE is configured with a master cell group (MCG) and multiple secondary cell groups (SCGs). Only one of the multiple SCGs is valid for the UE at a given time, and the UE connects to one or more cells of the valid SCG. In one optional implementation, the circuit determines the valid SCG to be a first SCG configured for the UE. The circuit determines the valid SCG based on a notification received from a source base station.

[0357] According to a thirteenth aspect provided in addition to the twelfth aspect, configuring an MCG and a plurality of SCGs in a UE includes: - The receiving unit includes, in operation, receiving configuration information of at least one of the MCG and the plurality of SCGs from the source base station, and optionally, the configuration information of the plurality of SCGs is received in a Radio Resource Control (RRC) message.

[0358] In one optional implementation, the configuration information is a common cell ID for the cells of each of said cell groups; a common frequency range for cells of each said cell group; common radio resources of cells of each cell group; Contains one or more of:

[0359] In one optional implementation, the configuration information for the SCG is o Contains a list of candidate cells for evaluation during conditional cell mobility procedures when the SCG is enabled.

[0360] According to a fourteenth aspect provided in addition to the twelfth or thirteenth aspects, a circuit comprises: ○ Random access to cells in each SCG, ○ Radio link measurements for each SCG's cells, and ○ Uplink synchronization for each SCG cell, One or more of the steps in (a) and (b) are performed for enabled SCGs but not for disabled SCGs.

[0361] According to a fifteenth aspect, provided in addition to any one of the twelfth to fourteenth aspects, each of the plurality of SCGs comprises: a combination of an identifier of a primary cell of each SCG and an identifier of a radio resource used by the cells of each SCG for transmission and reception, optionally the identifier of the radio resource being an Absolute Radio Frequency Channel Number (ARFCN), or ○ SCG identifier to distinguish between multiple SCGs is identified by

[0362] According to a 16th aspect provided in addition to any one of the 12th to 15th aspects, a UE stores information associating each of a plurality of SCGs with a cell. Upon successful completion of a conditional cell mobility procedure for a candidate target cell, the circuit determines, based on the stored information, an SCG associated with the candidate target cell of the completed conditional cell mobility procedure. In one optional implementation, the circuit uses configuration information of the determined SCG.

[0363] According to a seventeenth aspect, there is provided a base station comprising: circuitry in the base station that generates a plurality of cell configurations for a plurality of candidate target cells, each cell configuration having cell configuration parameters for performing a conditional cell mobility procedure between a user equipment (UE) and each of the candidate target cells, and an execution condition for when to perform the conditional cell mobility procedure for each of the candidate target cells; the plurality of cell configurations including a first subset of cell configurations that are evaluated by the UE when the UE is connected to the base station; and a second subset of cell configurations that are evaluated by the UE when connected to a first candidate target cell of the plurality of candidate target cells that is different from a source cell of the base station. A transmitter unit in the base station transmits the generated plurality of cell configurations to the UE.

[0364] According to an eighteenth aspect provided in addition to the seventeenth aspect, generating a plurality of cell configurations includes: a transmitting unit transmitting a request to a first candidate target cell to request cell configuration parameters of the first candidate target cell; a receiving unit receiving, in response to a request, from the first candidate target cell, a cell configuration of at least one other candidate target cell, the cell configuration of the other candidate target cell including cell configuration parameters of the other candidate target cell to be used by the UE when the UE is connected to the first candidate target cell, and an execution condition regarding when to perform a conditional cell mobility procedure between the UE and the other candidate target cell when the UE is connected to the first candidate target cell; Includes:

[0365] In one optional implementation, the receiving unit receives requested cell configuration parameters of the first candidate target cell from the first candidate target cell, and the circuit determines an execution condition for the requested cell configuration parameters of the first candidate target cell regarding when to perform a conditional cell mobility procedure between the UE and the first candidate target cell. In a further optional implementation, the circuit generates a cell configuration for the first candidate target cell based on the received cell configuration parameters of the first candidate target cell and the determined execution condition for the first candidate target cell.

[0366] According to a 19th aspect provided in addition to the 17th aspect or the 18th aspect, a transmitter transmits a cell status notification to a UE. The cell status notification includes: candidate cells for which the associated cell configuration is to be activated; Candidate cells whose associated cell configurations are to be disabled Indicates one or more of the following.

[0367] In one optional implementation, the cell state notification is in a Radio Resource Control (RRC) message, or In the control element of a Medium Access Control (MAC) message He is transported.

[0368] In one further optional implementation, the cell status notification is a bitmap, each bit of the bitmap corresponds to one candidate target cell of a plurality of candidate target cells, and one value of the bit indicates enabling the cell configuration of the associated candidate target cell, and another value of the bit indicates disabling the cell configuration of the associated candidate target cell.

[0369] According to a twentieth aspect provided in addition to any one of the seventeenth to nineteenth aspects, a UE is configured with a master cell group (MCG) and multiple secondary cell groups (SCGs). Only one secondary cell group is active for the UE at a given time, and the UE is connected to one or more cells in the active secondary cell group. A transmitter transmits a notification to the UE indicating which secondary cell group is active.

[0370] According to a 21st aspect provided in addition to the 20th aspect, a transmitter transmits configuration information of at least one of a master cell group and a plurality of secondary cell groups to a UE. In one optional implementation, the configuration information of the plurality of SCGs is transmitted in a Radio Resource Control (RRC) message. In one optional implementation, the configuration information includes: Common cell IDs for the cells in each cell group, the common frequency range of the cells in each cell group; Common radio resources for cells in each cell group Contains one or more of:

[0371] In a further optional implementation, the configuration information for the SCG is: List of candidate cells for evaluation for conditional cell mobility procedures upon SCG activation Includes:

[0372] According to a 22nd aspect, a base station comprises: a receiving unit of the base station receives, from a source base station, a request requesting cell configuration parameters of the base station for performing a conditional cell mobility procedure between a user equipment (UE) connected to the source base station and the base station; a circuit of the base station, when receiving the request, generates a cell configuration of at least one other candidate target cell; the cell configuration of the other candidate target cell includes cell configuration parameters of the other candidate target cell to be used when the UE is connected to the base station, and includes an execution condition regarding when to perform conditional cell mobility between the UE connected to the base station and the other candidate target cell; a transmitting unit of the base station transmits the generated cell configuration of the at least one other candidate target cell to the source base station.

[0373] According to a 23rd aspect provided in addition to the 22nd aspect, generating a cell configuration of at least one other candidate target cell includes: a transmitting unit transmitting a request to the other candidate target cell to request cell configuration parameters of the other candidate target cell; a receiving unit receiving, from the other candidate target cell, requested cell configuration parameters of the other candidate target cell; The circuit determines an execution condition regarding when to execute a conditional mobility procedure between the UE connected to the base station and another candidate target cell; Includes:

[0374] According to a 24th aspect provided in addition to the 22nd or 23rd aspect, a transmitter transmits a notification to the UE indicating a subset of cell configurations to be evaluated by the UE.

[0375] According to a 25th aspect provided in addition to any one of the 22nd to 24th aspects, the circuit generates requested cell configuration parameters for the base station when receiving the request, and a transmitter transmits the generated cell configuration parameters for the base station to the source base station.

[0376] According to a 26th aspect, the following steps are performed by a user equipment (UE): receiving, from a source base station, a plurality of cell configurations for a plurality of candidate target cells, each cell configuration including cell configuration parameters for performing a conditional cell mobility procedure for each candidate target cell and an execution condition for when to perform the conditional cell mobility procedure for each candidate target cell, the plurality of cell configurations including a first subset of cell configurations to be evaluated by the UE when connected to the source base station, and the plurality of cell configurations including a second subset of cell configurations to be evaluated by the UE when connected to a first candidate target cell of the plurality of candidate target cells that is different from the source cell of the source base station; evaluating only the execution conditions of a first subset of the cell configurations; performing a conditional cell mobility procedure for the first candidate target cell based on cell configuration parameters of the first candidate target cell if the evaluated execution conditions of the cell configurations of the first subset of cell configurations are satisfied for the first candidate target cell; A method is provided which includes:

[0377] According to a 27th aspect, the following steps are performed by a base station: generating a plurality of cell configurations for a plurality of candidate target cells, each cell configuration including cell configuration parameters for performing a conditional cell mobility procedure between a user equipment (UE) and each candidate target cell and an execution condition for when to perform the conditional cell mobility procedure for each candidate target cell, the plurality of cell configurations including a first subset of cell configurations to be evaluated when the UE is connected to the base station, and the plurality of cell configurations including a second subset of cell configurations to be evaluated when the UE is connected to a first candidate target cell of the plurality of candidate target cells that is different from a source cell of the base station; sending the generated multiple cell configuration to the UE; A method is provided which includes:

[0378] According to a 28th aspect, the following steps are performed by a base station: receiving, from a source base station, a request for cell configuration parameters of the base station for performing a conditional cell mobility procedure between a user equipment (UE) connected to the source base station and the base station; generating, when receiving the request, a cell configuration of at least one other candidate target cell, the cell configuration of the other candidate target cell including cell configuration parameters of the other candidate target cell to be used by a UE connected to the base station and an execution condition regarding when to execute conditional cell mobility between the UE connected to the base station and the other candidate target cell; sending the generated cell configuration of at least one other candidate target cell to the source base station; A method is provided which includes:

[0379] According to a twenty-ninth aspect, the integrated circuit, in operation, controls processing of a user equipment (UE), the processing comprising the following steps performed by the UE: receiving, from a source base station, a plurality of cell configurations for a plurality of candidate target cells, each including cell configuration parameters for executing a conditional cell mobility procedure for each candidate target cell and an execution condition for when to execute the conditional cell mobility procedure for each candidate target cell, wherein the plurality of cell configurations includes a first subset of cell configurations to be evaluated by the UE when the UE is connected to the source base station, and the plurality of cell configurations includes a second subset of cell configurations to be evaluated by the UE when the UE is connected to a first candidate target cell of the plurality of candidate target cells that is different from a source cell of the source base station; evaluating only the execution conditions of a first subset of the cell configurations; and if the evaluated execution conditions of the cell configurations of the first subset of cell configurations are satisfied for the first candidate target cell, performing a conditional cell mobility procedure for the first candidate target cell based on cell configuration parameters of the first candidate target cell.

[0380] According to a thirtieth aspect, the integrated circuit, in operation, controls processing of a base station, the processing comprising the following steps performed by the base station: generating a plurality of cell configurations for a plurality of candidate target cells, each including cell configuration parameters for performing a conditional cell mobility procedure between a user equipment (UE) and each candidate target cell and an execution condition for when to perform the conditional cell mobility procedure for each candidate target cell, wherein the plurality of cell configurations includes a first subset of cell configurations to be evaluated when the UE is connected to a base station, and the plurality of cell configurations includes a second subset of cell configurations to be evaluated when the UE is connected to a first candidate target cell of the plurality of candidate target cells that is different from a source cell of the base station; and transmitting the generated multiple cell configurations to the UE.

[0381] According to a thirty-first aspect, the integrated circuit, in operation, controls processing of a base station, the processing performed by the base station comprising: receiving, from a source base station, a request for cell configuration parameters of the base station for performing a conditional cell mobility procedure between a user equipment (UE) connected to the source base station and the base station; generating a cell configuration of at least one other candidate target cell when receiving a request, wherein the cell configuration of the other candidate target cell includes cell configuration parameters of the other candidate target cell to be used by the UE when connected to the base station and an execution condition regarding when to execute conditional cell mobility between the UE and the other candidate target cell when the UE is connected to the base station; and transmitting the generated cell configuration of the at least one other candidate target cell to the source base station.

[0382] According to a 32nd aspect, a user equipment (UE) comprises: a receiver of the UE receives a first set of one or more cell configurations; each cell configuration includes cell configuration parameters for performing a conditional cell mobility procedure for each candidate target cell and includes an execution condition for when to perform the conditional cell mobility procedure for each candidate target cell; at least one cell configuration of each candidate target cell includes a cell pre-configuration for another candidate target cell different from each candidate target cell; the cell pre-configuration includes cell configuration parameters for performing the conditional cell mobility procedure for the other candidate target cell, to be used by the UE when the UE is connected to each candidate target cell; a circuit of the UE evaluates the execution condition of the first set of cell configurations; and, if the execution condition is met for each candidate target cell in the first set of cell configurations, the circuit performs the conditional cell mobility procedure for each candidate target cell based on the cell configuration parameters of the each candidate target cell. Upon successful completion of the conditional cell mobility procedure, the circuit: storing the cell pre-configuration of the other candidate target cell as the cell configuration of the other candidate target cell; Release the first set of stored cell settings; Evaluate the execution conditions of the newly stored cell configuration of other candidate target cells.

[0383] According to a 33rd aspect, there is provided a base station comprising: circuitry of the base station generates a first set of one or more cell configurations; each cell configuration includes cell configuration parameters for performing a conditional cell mobility procedure for each candidate target cell and includes an execution condition for when to perform the conditional cell mobility procedure for each candidate target cell; at least one cell configuration of each candidate target cell includes a cell pre-configuration of another candidate target cell different from each candidate target cell; the cell pre-configuration includes cell configuration parameters for performing the conditional cell mobility procedure for the other candidate target cell, to be used by the UE when the UE is connected to each candidate target cell; and a transmitter unit of the base station transmits the generated first set of one or more cell configurations to the UE.

[0384] According to a thirty-fourth aspect provided in addition to the thirty-third aspect described above, generating a first set of one or more cell configurations comprises: a transmitter transmitting a request to a first candidate target cell to request cell configuration parameters of the first candidate target cell; The method includes receiving, by a receiving unit, in response to a request, a cell configuration of at least one other candidate target cell from the first candidate target cell, the cell configuration of the other candidate target cell including cell configuration parameters of the other candidate target cell to be used by the UE when the UE is connected to the first candidate target cell, and including an execution condition regarding when to execute a conditional cell mobility procedure between the UE connected to the first candidate target cell and the other candidate target cell.

[0385] In one optional implementation, the receiver receives from the first candidate target cell requested cell configuration parameters of the first candidate target cell, and the circuit determines an execution condition for the requested cell configuration parameters of the first candidate target cell regarding when to execute a conditional cell mobility procedure between the UE and the first candidate target cell. cell configuration parameters of the first candidate target cell received from the first candidate target cell and an execution condition determined for the first candidate target cell; cell configurations of other candidate target cells received from the first candidate target cell; and to generate a cell configuration for the first candidate target cell, including:

[0386] According to a thirty-fifth aspect, the method comprises the following steps performed by a user equipment (UE): receiving a first set of one or more cell configurations, each cell configuration including cell configuration parameters for performing a conditional cell mobility procedure for each candidate target cell and an execution condition for when to perform the conditional cell mobility procedure for each candidate target cell, at least one cell configuration for each candidate target cell including cell pre-configurations for other candidate target cells different from each candidate target cell, the cell pre-configurations including cell configuration parameters for performing the conditional cell mobility procedure for the other candidate target cells to be used by the UE when the UE is connected to each candidate target cell; evaluating a first set of execution conditions for the cell configuration; performing a conditional cell mobility procedure for each candidate target cell of the first set of cell configurations based on cell configuration parameters of the candidate target cell if an execution condition is met for the candidate target cell; If the conditional cell mobility procedure is completed successfully, storing the cell pre-configuration of the other candidate target cell as a cell configuration of the other candidate target cell; clearing a first set of stored cell configurations; evaluating the execution conditions of the newly stored cell configuration of other candidate target cells; A method is provided which includes:

[0387] According to a thirty-sixth aspect, the following steps are performed by a base station: generating a first set of one or more cell configurations, each cell configuration including cell configuration parameters for performing a conditional cell mobility procedure for each candidate target cell and an execution condition for when to perform the conditional cell mobility procedure for each candidate target cell, at least one cell configuration for each candidate target cell including cell pre-configurations for other candidate target cells different from each candidate target cell, the cell pre-configurations including cell configuration parameters for performing the conditional cell mobility procedure for the other candidate target cells, to be used by the UE when the UE is connected to each candidate target cell; transmitting the generated first set of one or more cell configurations to the UE; A method is provided which includes:

[0388] According to a thirty-seventh aspect, there is provided an integrated circuit that, in operation, controls processing of a user equipment (UE), the processing comprising the following steps performed by the user equipment (UE): receiving a first set of one or more cell configurations, each cell configuration including cell configuration parameters for performing a conditional cell mobility procedure for each candidate target cell and an execution condition for when to perform the conditional cell mobility procedure for each candidate target cell, at least one cell configuration for each candidate target cell including cell pre-configurations for other candidate target cells different from each candidate target cell, the cell pre-configurations including cell configuration parameters for performing the conditional cell mobility procedure for the other candidate target cells to be used by the UE when the UE is connected to each candidate target cell; evaluating a first set of execution conditions for the cell configuration; performing a conditional cell mobility procedure for each candidate target cell of the first set of cell configurations based on a cell configuration parameter of the candidate target cell if an execution condition is met for the candidate target cell; If the conditional cell mobility procedure is completed successfully, storing the cell pre-configuration of the other candidate target cell as a cell configuration of the other candidate target cell; clearing a first set of stored cell configurations; evaluating the execution conditions of the newly stored cell configuration of other candidate target cells; An integrated circuit is provided, including:

[0389] According to a thirty-eighth aspect, there is provided an integrated circuit that, in operation, controls processing of a base station, the processing comprising the following steps performed by the base station: generating a first set of one or more cell configurations, each cell configuration including cell configuration parameters for performing a conditional cell mobility procedure for a respective candidate target cell and an execution condition for when to perform the conditional cell mobility procedure for each candidate target cell, wherein at least one cell configuration for each candidate target cell includes cell pre-configurations for other candidate target cells different from each candidate target cell, the cell pre-configurations including cell configuration parameters for performing the conditional cell mobility procedure for the other candidate target cells, to be used by the UE when the UE is connected to each candidate target cell; transmitting the generated first set of one or more cell configurations to the UE; An integrated circuit is provided, including:

[0390] Further variations including hardware and software implementations of the present disclosure The present disclosure can be implemented by software, hardware, or software operating in conjunction with hardware. Each functional block used in the above-described embodiments can be implemented, in whole or in part, by an LSI such as an integrated circuit. Each process described in each embodiment can be controlled, in whole or in part, by the same LSI or a combination of LSIs. The LSI can be formed as an individual chip, or a single chip can be formed to include some or all of the functional blocks. The LSI can include a data input / output unit coupled to it. Depending on the level of integration, the LSI can also be referred to as an IC (integrated circuit), system LSI, super LSI, or ultra LSI. However, the technology for implementing an integrated circuit is not limited to LSI, and can be implemented using dedicated circuits, general-purpose processors, or dedicated processors. Furthermore, FPGAs (field programmable gate arrays), which can be programmed after LSI fabrication, and reconfigurable processors, which can reconfigure the connections and settings of circuit cells arranged within the LSI, can also be used. The present disclosure can be implemented using digital or analog processing. If, as a result of advances in semiconductor technology or other derivative technologies, LSI is replaced by future integrated circuit technologies, these future integrated circuit technologies can be used to integrate functional blocks. Biotechnology can also be applied.

[0391] The present disclosure may be implemented by any type of apparatus, device, or system having communication capabilities, referred to as a communications apparatus.

[0392] A communication device may include the transceiver and processing / control circuitry described above. The transceiver may include and / or function as a receiver and a transmitter. The transceiver as a transmitter and a receiver may include an RF (radio frequency) module including an amplifier, an RF modulator / demodulator, etc., and one or more antennas.

[0393] Some non-limiting examples of such communication devices include telephones (e.g., mobile phones, smartphones), tablets, personal computers (PCs) (e.g., laptops, desktops, notebooks), cameras (e.g., digital still / video cameras), digital players (digital audio / video players), wearable devices (e.g., wearable cameras, smart watches, tracking devices), game consoles, e-readers, telehealth / telemedicine devices, vehicles (e.g., cars, airplanes, ships) that provide communication capabilities, and various combinations thereof.

[0394] Communication devices are not limited to portable or mobile devices, but can also include any type of equipment, device, or system that is non-portable or fixed, such as smart home devices (e.g., appliances, lights, smart meters, control panels), vending machines, and any other "thing" in an "Internet of Things" (IoT) network.

[0395] Communication can include, for example, exchanging data through cellular systems, wireless LAN systems, satellite systems, etc., and various combinations thereof.

[0396] A communications device may include devices such as a controller or a sensor coupled to the communications device to perform the communications functions described in this disclosure. For example, a communications device may include a controller or a sensor that generates control or data signals used by the communications device to perform the communications functions of the communications device.

[0397] The communications apparatus may further include infrastructure facilities, such as base stations, access points, and any other apparatus, device, or system that communicate with or control apparatuses such as the apparatuses in the non-limiting examples above.

[0398] (control signal) In the present disclosure, the downlink control signal (information) related to the present disclosure may be a signal (information) transmitted via a PDCCH of a physical layer, or may be a signal (information) transmitted via a MAC Control Element (CE) or RRC of a higher layer. The downlink control signal may be a predefined signal (information).

[0399] The uplink control signal (information) related to the present disclosure may be a signal (information) transmitted via a PUCCH in the physical layer or a signal (information) transmitted via a MAC CE or RRC in a higher layer. The uplink control signal may also be a predefined signal (information). The uplink control signal may be replaced with uplink control information (UCI), first-stage sidelink control information (SCI), or second-stage SCI.

[0400] (base station) In the present disclosure, a base station may be, for example, a Transmission Reception Point (TRP), a cluster head, an access point, a Remote Radio Head (RRH), an eNodeB (eNB), a gNodeB (gNB), a Base Station (BS), a Base Transceiver Station (BTS), a base unit, or a gateway. In addition, a terminal may be employed instead of a base station in sidelink communication. The base station may be a relay device that relays communication between an upper node and a terminal. The base station may be a roadside unit.

[0401] (Uplink / Downlink / Sidelink) The present disclosure may be applied to any of the uplink, downlink, and sidelink.

[0402] The present disclosure may be applied, for example, to uplink channels such as PUSCH, PUCCH, and PRACH, downlink channels such as PDSCH, PDCCH, and PBCH, and sidelink channels such as the Physical Sidelink Shared Channel (PSSCH), the Physical Sidelink Control Channel (PSCCH), and the Physical Sidelink Broadcast Channel (PSBCH).

[0403] The PDCCH, PDSCH, PUSCH, and PUCCH are examples of a downlink control channel, a downlink data channel, an uplink data channel, and an uplink control channel, respectively. The PSCCH and PSSCH are examples of a sidelink control channel and a sidelink data channel, respectively. The PBCH and PSBCH are examples of a broadcast channel, and the PRACH is an example of a random access channel. (Data channel / Control channel) The present disclosure may be applied to both data channels and control channels. The channels in this disclosure may be replaced with data channels including PDSCH, PUSCH, and PSSCH, and / or control channels including PDCCH, PUCCH, PBCH, PSCCH, and PSBCH.

[0404] (reference signal) In this disclosure, a reference signal is a signal known to both a base station and a mobile station, and each reference signal may be referred to as a reference signal (RS) or, in some cases, a pilot signal. A reference signal may be any of a DMRS, a Channel State Information-Reference Signal (CSI-RS), a Tracking Reference Signal (TRS), a Phase Tracking Reference Signal (PTRS), a Cell-specific Reference Signal (CRS), and a Sounding Reference Signal (SRS).

[0405] (time interval) In the present disclosure, the time resource unit is not limited to one or a combination of a slot and a symbol, and may be a time resource unit such as a frame, a superframe, a subframe, a slot, a time slot subslot, a minislot, a symbol, an Orthogonal Frequency Division Multiplexing (OFDM) symbol, a Single Carrier-Frequency Division Multiplexing Access (SC-FDMA) symbol, or other time resource unit. The number of symbols included in one slot is not limited to any of the numbers of symbols exemplified in the above embodiment(s), and may be other numbers of symbols.

[0406] (frequency band) The present disclosure may be applied to both licensed and unlicensed bands.

[0407] (communication) The present disclosure may be applied to communication between a base station and a terminal (Uu link communication), communication between terminals (sidelink communication), and vehicle-to-everything (V2X) communication. The channels in the present disclosure may be replaced with PSCCH, PSSCH, Physical Sidelink Feedback Channel (PSFCH), PSBCH, PDCCH, PUCCH, PDSCH, PUSCH, and PBCH.

[0408] The present disclosure may also be applied to terrestrial networks or non-terrestrial networks (NTNs) that use satellites or high altitude pseudo satellites (HAPSs). The present disclosure may also be applied to networks with large cell sizes and terrestrial networks with large delays compared to the symbol length or slot length, such as ultra-wideband transmission networks.

[0409] (antenna port) An antenna port refers to a logical antenna (antenna group) formed by one or more physical antennas (multiple antennas are possible). That is, an antenna port does not necessarily refer to one physical antenna, but may refer to an array antenna formed by multiple antennas. For example, the number of physical antennas forming an antenna port is not defined. Instead, an antenna port is defined as the smallest unit by which a terminal can transmit a reference signal. An antenna port may also be defined as the smallest unit for multiplying a weight of a precoding vector.

[0410] Furthermore, the various embodiments may be implemented by means of software modules, which are executed by a processor or directly in hardware. A combination of software modules and hardware implementations is also possible. The software modules may be stored on any kind of computer-readable storage medium, for example RAM, EPROM, EEPROM, flash memory, registers, hard disks, CD-ROM, DVD, etc. Furthermore, it should be noted that individual features of the different embodiments may also be the subject of another embodiment, individually or in any combination.

[0411] It will be appreciated by those skilled in the art that various changes and / or modifications may be made to the present disclosure as set forth in the specific embodiments without departing from the concept or scope of the invention as broadly described. The embodiments described herein are therefore to be considered in all respects as illustrative and not restrictive.< / condreconfigid> < / condreconfigtoaddmodlist> < / conditionalreconfiguration>

Claims

1. A communication device, a receiver that, during operation, receives from a source base station a plurality of cell configurations of a plurality of candidate target cells, each cell configuration including cell configuration parameters and an execution condition for a conditional cell mobility procedure, the plurality of cell configurations including a first subset of cell configurations to be used when the communication device is connected to the source base station and a second subset of cell configurations to be used when the communication device is connected to a first candidate target cell of the plurality of candidate target cells; a circuit for evaluating, in operation, an execution condition of a first subset of the cell configurations, and for executing, in operation, the conditional cell mobility procedure for the first candidate target cell based on cell configuration parameters of the first candidate target cell if the evaluated execution condition of the first subset of the cell configurations is satisfied for the first candidate target cell; A communication device comprising:

2. the circuitry, if the conditional cell mobility procedure between the communication device and the first candidate target cell is successfully completed, maintaining the received plurality of cell configurations; evaluating execution conditions for a second subset of the cell configurations; The circuit, in operation, if each subset of cell configurations of the plurality of cell configurations is associated with one cell, based on a cell to which the communication device is currently connected; based on a notification received from the first candidate target cell indicating a subset of cell configurations to be evaluated by the communications device; determining a second subset of the cell configurations to be evaluated; The communication device according to claim 1 .

3. evaluating the first subset of cell configurations includes the circuit not evaluating execution conditions of remaining cell configurations of a plurality of candidate target cells that do not belong to the first subset of cell configurations. The communication device according to claim 1 .

4. the plurality of cell configurations includes more than x cell configurations; the plurality of cell configurations is arranged in a sequence of cell configurations, the first subset of cell configurations comprising the first x element cell configurations in the sequence; the number x is 8; The communication device according to claim 1 .

5. the plurality of cell configurations includes x cell configurations; the first subset of cell configurations includes fewer than the x cell configurations; the number x is 8; The communication device according to claim 1 .

6. The cell configurations belonging to the first subset are associated with an enabled state, and the remaining cell configurations of the plurality of cell configurations that do not belong to the first subset are associated with a disabled state; a cell configuration associated with the disabled state is not evaluated by the communication device when performing the conditional cell mobility procedure, and a cell configuration associated with the enabled state is evaluated by the communication device when performing the conditional cell mobility procedure. The communication device according to claim 1 .

7. the plurality of cell configurations includes two or more cell configurations associated with one candidate target cell; the first subset includes one or more cell configurations that are less than all of the plurality of cell configurations; the cell configurations in the first subset are each for a different candidate target cell; the plurality of cell configurations includes one subset of cell configurations for each cell configuration in the first subset; The communication device according to claim 1 .

8. The receiver, when operating, receives a cell status notification from the source base station, the cell status notification comprising: indicating one or more candidate cells for which the associated cell configuration is to be enabled or disabled; The cell status notification includes: carried in a Radio Resource Control (RRC) message, or carried in the control element of a Medium Access Control (MAC) message; the cell status notification is a bitmap, each bit of the bitmap is associated with one candidate target cell of the plurality of candidate target cells, one value of the bit indicates enabling cell configuration of the associated candidate target cell, and another value of the bit indicates disabling cell configuration of the associated candidate target cell; The communication device according to claim 1 .

9. The conditional cell mobility procedure comprises: a conditional handover, where if the execution condition is met, the communications device is disconnected from a source cell and connected to a candidate target cell, the source cell and the candidate target cell belonging to the same master cell group of the communications device; a conditional cell change, where if the execution condition is met, the communications device is disconnected from the source cell and connected to a candidate target cell, the source cell and the candidate target cell belonging to a secondary cell group of the communications device that is different from a master cell group of the communications device; and a conditional cell addition, wherein if the execution condition is met, the communications device connects to a candidate target cell, the candidate target cell being a primary cell of a secondary cell group of the communications device that is different from a master cell group of the communications device. One of the The communication device according to claim 1 .

10. The cell configuration parameters of the cell configuration are: radio resource configuration of said candidate target cells, such as resource block, physical channel configuration, etc.; security configuration of said candidate target cells; Dual connectivity information such as master cell group information, secondary cell group information, etc. - measurement configuration of said candidate target cells; Mobility settings, and the execution condition regarding when to perform the conditional cell mobility procedure includes one or more sub-conditions, and the execution condition is fulfilled when one or all of the sub-conditions are fulfilled, and the sub-conditions relate to communication qualities of one or more of the source cell and the candidate target cells related to the execution condition; The communication device according to claim 9.

11. Each cell configuration of the first subset includes cell configuration parameters and the execution condition of the conditional cell mobility procedure from the source cell to each candidate target cell; each cell configuration of the second subset includes a cell configuration parameter and the execution condition of a conditional cell mobility procedure from the first candidate target cell to each candidate target cell; The communication device according to claim 9 or 10.

12. The communication device is configured with a master cell group (MCG) and multiple secondary cell groups (SCGs), one of the multiple SCGs is active for the communication device at a given time, and the communication device is connected to one or more cells of the active SCG; In operation, the circuit determines the valid SCG to be a first SCG configured for the communication device; The circuit, in operation, determines the valid SCG based on a notification received from the source base station. The communication device according to claim 1 .

13. Configuring the MCG and the plurality of SCGs in the communication device includes: the receiving unit, during operation, receiving from the source base station configuration information of at least one of the MCG and the plurality of SCGs, wherein the configuration information of the plurality of SCGs is received in a Radio Resource Control (RRC) message; - said setting information is a common cell ID for the cells of each of said cell groups; a common frequency range for cells of each said cell group; common radio resources of cells of each cell group; and - The setting information of the SCG is o Contains a list of candidate cells for evaluation during a conditional cell mobility procedure when the SCG is enabled, The communication device of claim 12.

14. In operation, the circuitry performs the following for the valid SCG: Random access to cells of each SCG, Radio link measurements for the cells of each SCG, and o Uplink synchronization for each SCG cell, performing one or more of the steps of 14. A communication device according to claim 12 or 13.

15. Each of the plurality of SCGs comprises: a combination of an identifier of a primary cell of each SCG and an identifier of a radio resource used by a cell of each SCG for transmission and reception, the identifier of the radio resource being an Absolute Radio Frequency Channel Number (ARFCN), or an SCG identifier for distinguishing between the plurality of SCGs; Identified by, The communication device of claim 12.

16. The communications device stores information associating each of the plurality of SCGs with a cell, and the circuitry, upon successful completion of a conditional cell mobility procedure for the candidate target cell, determines an SCG associated with the candidate target cell of the completed conditional cell mobility procedure based on the stored information; The circuit uses the determined SCG setting information during operation. The communication device of claim 12.

17. the at least one cell configuration of each candidate target cell includes cell pre-configurations of other candidate target cells; If the conditional cell mobility procedure is completed successfully, the circuitry, in operation, storing a cell pre-configuration of said other candidate target cell as a cell configuration of said other candidate target cell; canceling the received plurality of cell configurations; evaluating the stored cell configuration execution conditions of the other candidate target cells; The communication device according to claim 1 .

18. a circuit configured to, in operation, generate a plurality of cell configurations for a plurality of candidate target cells, each cell configuration including cell configuration parameters and a condition for executing a conditional cell mobility procedure, the plurality of cell configurations including: a first subset of cell configurations to be used when connected to a base station; and a second subset of cell configurations to be used when connected to a first candidate target cell of the plurality of candidate target cells; a transmitter that, in operation, transmits the generated plurality of cell configurations to a communication device; A base station comprising:

19. generating the plurality of cell configurations, the transmitter, in operation, transmitting a request to the first candidate target cell to request the cell configuration parameters of the first candidate target cell; a receiving unit, in operation, receiving from the first candidate target cell in response to the request, the cell configuration of at least one other candidate target cell, the cell configuration of the other candidate target cell including cell configuration parameters of the other candidate target cell to be used by the communication device when the communication device is connected to the first candidate target cell, and the execution condition regarding when to execute the conditional cell mobility procedure between the communication device and the other candidate target cell when connected to the first candidate target cell; the receiving unit, in operation, receives from the first candidate target cell the requested cell configuration parameters of the first candidate target cell, and the circuit, in operation, determines the execution condition for the requested cell configuration parameters of the first candidate target cell regarding when to execute the conditional cell mobility procedure between the communication device and the first candidate target cell; the circuitry, in operation, generating the cell configuration for the first candidate target cell based on the received cell configuration parameters for the first candidate target cell and the determined execution condition for the first candidate target cell; 20. The base station of claim 18, comprising:

20. a receiver for receiving, in operation, a request from a source base station for requesting cell configuration parameters of the base station for a conditional cell mobility procedure; a circuit for generating a cell configuration of at least one other candidate target cell in response to receiving the request, wherein the cell configuration of the other candidate target cell includes the cell configuration parameters of the other candidate target cell and an execution condition for the conditional cell mobility; a transmitter configured, during operation, to transmit the generated cell configuration of the at least one other candidate target cell to the source base station; A base station comprising:

21. The generation of the cell configuration of the at least one other candidate target cell includes: the transmitting unit, in operation, transmitting a request to the other candidate target cell to request cell configuration parameters of the other candidate target cell; the receiving unit, in operation, receiving from the other candidate target cell the requested cell configuration parameters of the other candidate target cell; and the circuit, when operating, determines the execution condition regarding when to execute the conditional mobility procedure between a communication device connected to the base station and the other candidate target cell.

21. The base station of claim 20.

22. The following steps are performed by the communication device: receiving from a source base station a plurality of cell configurations for a plurality of candidate target cells, each cell configuration including cell configuration parameters and a condition for performing a conditional cell mobility procedure, the plurality of cell configurations including a first subset of cell configurations to be used when connected to the source base station and a second subset of cell configurations to be used when connected to a first candidate target cell of the plurality of candidate target cells; evaluating the execution conditions of a first subset of the cell configurations; performing the conditional cell mobility procedure for the first candidate target cell based on the cell configuration parameters of the first candidate target cell if the evaluated execution conditions of a first subset of cell configurations are satisfied for the first candidate target cell; A method comprising:

23. The following steps are performed by the base station: generating a plurality of cell configurations for a plurality of candidate target cells, each cell configuration including cell configuration parameters and execution conditions for a conditional cell mobility procedure, the plurality of cell configurations including a first subset of cell configurations to be used when connected to the base station and a second subset of cell configurations to be used when connected to a first candidate target cell of the plurality of candidate target cells; transmitting the generated cell configurations to a communication device; A method comprising:

24. 1. An integrated circuit which, in operation, controls the processing of a communications device, said processing comprising the following steps performed by said communications device: receiving from a source base station a plurality of cell configurations for a plurality of candidate target cells, each cell configuration including cell configuration parameters and a condition for performing a conditional cell mobility procedure, the plurality of cell configurations including a first subset of cell configurations to be used when connected to the source base station and a second subset of cell configurations to be used when connected to a first candidate target cell of the plurality of candidate target cells; evaluating the execution conditions of a first subset of the cell configurations; performing the conditional cell mobility procedure for the first candidate target cell based on the cell configuration parameters of the first candidate target cell if the evaluated execution conditions of a first subset of cell configurations are satisfied for the first candidate target cell; , an integrated circuit.

25. An integrated circuit that, in operation, controls the processing of a base station, said processing comprising the following steps performed by said base station: generating a plurality of cell configurations for a plurality of candidate target cells, each cell configuration including cell configuration parameters and execution conditions for a conditional cell mobility procedure, the plurality of cell configurations including a first subset of cell configurations to be used when connected to the base station and a second subset of cell configurations to be used when connected to a first candidate target cell of the plurality of candidate target cells; transmitting the generated cell configurations to a communication device; , an integrated circuit.

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