User equipment and base station involved in cell mobility procedure

Abstract

The present disclosure relates to a user equipment, UE, comprising the following. A receiver receives a plurality of cell configurations from a source base station. Each cell configuration includes a cell configuration parameter for performing a conditional cell mobility procedure with the respective candidate target cell, and includes an execution condition regarding when to perform the conditional cell mobility procedure. The plurality of cell configurations includes a first subset of cell configurations to be evaluated by the UE when connected with the source base station. The plurality of cell configurations includes a second subset of cell configurations to be evaluated by the UE when connected with a first candidate target cell of the plurality of candidate target cells, the first candidate target cell being different from a source cell of the source base station. The circuitry of the UE evaluates only execution conditions for the first subset of the cell configurations.

Description

Technical Field

[0001] The present disclosure relates to methods, apparatus and products in a communication system, such as a 3GPP communication system. Background Art

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

[0003] One objective is to provide a single technical framework that addresses all usage scenarios, requirements, and deployment scenarios (see, e.g., Section 6 of 3GPP TR 38.913, e.g., Release 16.0.0 or Release 17.0.0), including at least enhanced mobile broadband (eMBB), ultra-reliable low latency communications (URLLC), and massive machine type communications (mMTC). For example, eMBB deployment scenarios may include indoor hotspots, dense urban, rural, urban macro, and high-speed; URLLC deployment scenarios may include industrial control systems, mobile healthcare (remote monitoring, diagnosis, and treatment), vehicle real-time control, wide-area monitoring and control systems for smart grids; mMTC deployment scenarios may include scenarios with a large number of devices (such as smart wearable devices) and sensor networks that perform non-real-time critical data transmission. Services eMBB and URLLC are similar in that they both require very wide bandwidth, while they differ in that URLLC services may preferably require ultra-low latency.

[0004] A second goal is to achieve forward compatibility, which facilitates completely new system designs and / or the introduction of novel features. Summary of the invention

[0005] One non-limiting and exemplary embodiment facilitates providing a process for a UE to perform an improved cell mobility procedure.

[0006] In an embodiment, the technology disclosed herein is characterized by a user equipment UE including the following items. A receiver of the UE receives multiple cell configurations for multiple candidate target cells from a source base station. Each cell configuration includes cell configuration parameters for performing a conditional cell mobility process with a corresponding candidate target cell, and includes an execution condition regarding when to perform the conditional cell mobility process with the corresponding candidate target cell. The multiple cell configurations include a first subset of cell configurations to be evaluated by the UE when connected to the source base station. The multiple cell configurations include a second subset of cell configurations to be evaluated by the UE when connected to a first candidate target cell among the multiple candidate target cells, the first candidate target cell being different from the source cell of the source base station. The circuit of the UE only evaluates the execution conditions of the first subset of cell configurations. The circuit performs the conditional cell mobility process with the first candidate target cell based on the cell configuration parameters of the first candidate target cell when the execution conditions of the cell configurations in the first subset of the evaluated cell configurations are met for the first candidate target cell.

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

[0008] Additional benefits and advantages of the disclosed embodiments and different implementations will be apparent from the description and drawings. Benefits and / or advantages can be obtained individually from the various embodiments and features of the description and drawings, and these embodiments and features do not need to be provided in full in order to obtain one or more such benefits and / or advantages. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Hereinafter, exemplary embodiments are described in more detail with reference to the accompanying drawings.

[0010] Figure 1 An exemplary architecture of a 3GPP NR system to which the improved procedures of the present disclosure may be applied is shown;

[0011] Figure 2 is a schematic diagram showing the functional division between an NG radio access network (NG-RAN) and a 5G core network (5GC) to which the improved process of the present disclosure can be applied,

[0012] Figure 3 is a sequence diagram of a radio resource control (RRC) connection establishment / reconfiguration procedure to which the improved procedure of the present disclosure may be applied,

[0013] Figure 4 is a schematic diagram showing usage scenarios of eMBB, mMTC and URLLC to which the improved process of the present disclosure can be applied,

[0014] Figure 5is a block diagram illustrating an exemplary 3GPP NR system architecture for non-roaming scenarios,

[0015] Figure 6 shows an overview of different cell types in dual connectivity,

[0016] Figure 7 is a signalling diagram for handover involving UE, source gNB and target gNB,

[0017] Figure 8 shows an exemplary conditional handover involving a UE, a source gNB and a target gNB,

[0018] Fig. 9 and Fig.10 Other exemplary conditional switching are shown respectively,

[0019] Fig.11 is a signaling diagram for the conditional PSCell change procedure,

[0020] Fig.12 is the signaling diagram for the conditional PSCell addition process,

[0021] Fig.13 shows an exemplary and simplified structure of a UE and a gNB,

[0022] Fig.14 The structure of the UE of an exemplary implementation of the improved mobility process according to the first technical solution is shown.

[0023] Fig.15 A flowchart showing UE behavior according to an exemplary implementation of an improved mobility process of the first technical solution,

[0024] Fig.16 The structure of the source base station of an exemplary implementation of the process of improving mobility according to the first technical solution is shown.

[0025] Fig.17 A flow chart showing the behavior of a source base station according to an exemplary implementation of an improved mobility process of the first technical solution,

[0026] Fig.18 The structure of the target base station of an exemplary implementation of the improved mobility process according to the first technical solution and the second technical solution is shown.

[0027] Fig.19 A flowchart showing the target base station behavior of an exemplary implementation of the improved mobility process according to the first technical solution and the second technical solution is provided.

[0028] Fig. 20is a signaling diagram showing an exemplary exchange between a UE, a source gNB, and a target gNB for an exemplary implementation of an improved mobility procedure (particularly an improved CHO procedure) of the first technical solution,

[0029] Fig.21 is a signaling diagram showing an exemplary exchange between a UE, a source gNB, and a target gNB for preparing a CHO configuration and a CHO pre-configuration according to an improved CHO procedure of the first technical solution,

[0030] Fig. 22 A signaling diagram showing an exemplary exchange between a UE, a source gNB, and a target gNB for an exemplary implementation of an improved CPC procedure for the first technical solution is shown,

[0031] Fig.23 A signaling diagram showing an exemplary exchange between a UE, a source gNB, and a target gNB for an exemplary implementation of an improved CPA procedure for the first technical solution is shown,

[0032] Fig.24 The structure of the UE of an exemplary implementation of the improved mobility process according to the second technical solution is shown.

[0033] Fig.25 A flowchart showing UE behavior according to an exemplary implementation of an improved mobility process of the second technical solution is shown,

[0034] Fig.26 The structure of the source base station of the exemplary implementation of the improved mobility process according to the second technical solution is shown.

[0035] Fig. 27 A flow chart showing the behavior of a source base station according to an exemplary implementation of an improved mobility process of the second technical solution;

[0036] Fig.28 A signaling diagram showing exemplary exchanges between a UE, a source gNB, and a target gNB for an exemplary implementation of the improved CPA procedure for the second technical solution is shown. DETAILED DESCRIPTION

[0037] 5G NR system architecture and protocol stack

[0038] 3GPP has been working on the next version of the fifth generation of cellular technology, or 5G for short, including the development of new radio access technologies operating in the frequency range up to 100GHz. The first version of the 5G standard was completed at the end of 2017, which allowed the continuation of 5G NR standard-compliant trials and commercial deployment of smartphones.

[0039] Apart from this, the overall system architecture assumes a NG-RAN (Next Generation Radio Access Network) including gNBs, thereby providing NG radio access user plane (SDAP / PDCP / RLC / MAC / PHY) and control plane (RRC) protocol terminations to the UE. The gNBs are interconnected to each other by means of the Xn interface. The gNB is also connected to the 5GC by means of the Next Generation (NG) interface, more specifically to the AMF (Access and Mobility Management Function) (e.g., a specific core entity that executes the AMF) by means of the NG-C interface, and to the UPF (User Plane Function) (e.g., a specific core entity that executes the UPF) by means of the NG-U interface. The NG-RAN architecture is Figure 1 (see, e.g., 3GPP TS 38.300, e.g., v16.8.0, Section 4).

[0040] The user plane protocol stack for NR (see, e.g., 3GPP TS 38.300, Section 4.4.1) consists of the PDCP (Packet Data Convergence Protocol, see Section 6.4 of 3GPP TS 38.300), RLC (Radio Link Control, see Section 6.3 of TS 38.300) and MAC (Medium Access Control, see Section 6.2 of TS 38.300) sublayers, which terminate in the gNB on the network side. In addition, a new access stratum (AS) sublayer (SDAP, Service Data Adaptation Protocol) is introduced on top of PDCP (see, e.g., subclause 6.5 of TS 38.300). A control plane protocol stack is also defined for NR (see, e.g., TS 38.300, Section 4.4.2). An overview of the Layer 2 functionality is given in subclause 6 of TS 38.300. The functionality of the RRC layer is listed in subclause 7 of TS 38.300.

[0041] For example, the medium access control layer handles logical channel multiplexing as well as scheduling and scheduling-related functions, including handling different parameter sets.

[0042] The physical layer (PHY) is responsible for, for example, coding, PHY HARQ processing, modulation, multi-antenna processing, and mapping signals to appropriate physical time-frequency resources. It also handles the 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 the transmission of a specific transport channel, and each transport channel is mapped to a corresponding physical channel. For example, physical channels are PRACH (Physical Random Access Channel), PUSCH (Physical Uplink Shared Channel) and PUCCH (Physical Uplink Control Channel) for uplink and PDSCH (Physical Downlink Shared Channel), PDCCH (Physical Downlink Control Channel) and PBCH (Physical Broadcast Channel) for downlink.

[0043] NR use cases / deployment scenarios can include enhanced mobile broadband (eMBB), ultra-reliable low latency communications (URLLC), massive machine type communications (mMTC), which have different requirements in terms of data rate, latency and coverage. For example, eMBB is expected to support peak data rates (20Gbps for downlink and 10Gbps for uplink) and user-experienced data rates that are approximately three times higher than those provided by IMT-Advanced. On the other hand, in the case of URLLC, there is a strong demand for ultra-low latency (0.5ms for both UL and DL for user plane latency) and high reliability (1-10ms within 1ms). -5 ) puts forward more stringent requirements. Finally, mMTC may preferably require high connection density (1,000,000 devices / km in urban environments) 2 ), large coverage in harsh environments, and extremely long battery life (15 years) for low-cost devices.

[0044] Therefore, an OFDM parameter set (e.g., subcarrier spacing, OFDM symbol duration, cyclic prefix (CP) duration, number of symbols per scheduling interval) that is suitable for one use case may not be well suited for another use case. For example, low-latency services may preferably require shorter symbol duration (and therefore larger subcarrier spacing) and / or fewer symbols per scheduling interval (aka TTI) compared to mMTC services. Furthermore, deployment scenarios with large channel delay spread may preferably require longer CP duration than scenarios with short delay spread. The subcarrier spacing should be optimized accordingly to retain similar CP overhead. NR can support more than one value of subcarrier spacing. Accordingly, subcarrier spacings of 15kHz, 30kHz, 60kHz, ... are currently being considered. Symbol duration T u and subcarrier spacing Δf by the formula Δf = 1 / T u In a similar manner as in the LTE system, the term "resource element" may be used to denote a minimum resource unit consisting of one subcarrier of the length of one OFDM / SC-FDMA symbol.

[0045] In the new radio system 5G-NR, for each parameter set and carrier, a resource grid of subcarriers and OFDM symbols is defined for uplink and downlink, respectively. Each element in the resource grid is called a resource element and is identified based on a frequency index in the frequency domain and a symbol position in the time domain (see 3GPP TS 38.211, e.g., v17.1.0, e.g., Section 4). For example, downlink and uplink transmissions are organized into frames with a duration of 10ms, each frame consisting of ten subframes with a duration of 1ms respectively. In a 5g NR implementation, the number of consecutive OFDM symbols per subframe depends on the subcarrier spacing configuration. For example, for a 15-kHz subcarrier spacing, a subframe has 14 OFDM symbols (similar to an LTE-compliant implementation, assuming a normal cyclic prefix). On the other hand, for a 30-kHz subcarrier spacing, a subframe has two slots, each of which includes 14 OFDM symbols.

[0046] 5G NR functional division between NG-RAN and 5GC

[0047] Figure 2 The functional division between NG-RAN and 5GC is shown. The NG-RAN logical node is gNB or ng-eNB. 5GC has logical nodes AMF, UPF and SMF.

[0048] In particular, gNB and ng-eNB host the following key functions:

[0049] - Functions for radio resource management, such as radio bearer control, radio admission control, connection mobility control, dynamic allocation of resources to UEs in both uplink and downlink (scheduling);

[0050] -IP header compression, encryption and data integrity protection;

[0051] - When the route to the AMF cannot be determined from the information provided by the UE, the AMF is selected at UE attach;

[0052] - Routing user plane data towards UPF;

[0053] - Routing control plane information towards the AMF;

[0054] -Connection establishment and release;

[0055] - Scheduling and transmission of paging messages;

[0056] - Scheduling and delivery of system broadcast information (originating from AMF or OAM);

[0057] - Measurements and measurement reporting configuration for mobility and scheduling;

[0058] -Transport level packet marking in uplink;

[0059] -Session management;

[0060] -Support network slicing;

[0061] -QoS flow management and mapping to data radio bearers;

[0062] -Support UE in RRC_INACTIVE state;

[0063] -NAS message distribution function;

[0064] - Radio access network sharing;

[0065] -Dual connection;

[0066] - Tight interworking between NR and E-UTRA.

[0067] The Access and Mobility Management Function (AMF) hosts the following key functions:

[0068] - Non-access stratum NAS signaling termination;

[0069] -NAS signaling security;

[0070] -Access layer AS security control;

[0071] - Core Network CN inter-node signalling for mobility between 3GPP access networks;

[0072] - Idle mode UE reachability (including control and execution of paging retransmissions);

[0073] -Registration area management;

[0074] -Support mobility within and between systems;

[0075] -Access authentication;

[0076] -Access authorization, including roaming permission checks;

[0077] - Mobility management control (subscription and policy);

[0078] -Support network slicing;

[0079] -Session management function SMF selection.

[0080] Additionally, the User Plane Function (UPF) hosts the following key functions:

[0081] - Anchor point for intra / inter-RAT mobility (when applicable);

[0082] - External PDU session points interconnected with the data network;

[0083] -Packet routing and forwarding;

[0084] -Packet inspection and user plane part of policy rule enforcement;

[0085] - Traffic usage report;

[0086] - Uplink classifier to support routing of traffic flows to the data network;

[0087] -Support branching points for multi-host PDU sessions;

[0088] - QoS processing in the user plane, such as packet filtering, gating, UL / DL rate enforcement;

[0089] - Uplink service verification (SDF to QoS flow mapping);

[0090] - Downlink packet buffering and downlink data notification triggering.

[0091] Finally, the session management function SMF hosts the following main functions:

[0092] -Session management;

[0093] -UE IP address allocation and management;

[0094] -Selection and control of UP function;

[0095] -Configure traffic steering at the user plane function UPF to route the traffic to the appropriate destination;

[0096] -Policy implementation and QoS control part;

[0097] - Downlink data notification.

[0098] RRC connection establishment and reconfiguration process

[0099] Figure 3 Some interactions between the UE, gNB and AMF (5GC entity) are shown in the context of the UE transitioning from RRC_IDLE to RRC_CONNECTED for the NAS part (see 3GPP TS 38.300).

[0100] RRC is a high-level signaling (protocol) used for UE and gNB configuration. Specifically, the transition may involve the AMF preparing UE context data (including, for example, PDU session context, security keys, UE radio capabilities, and UE security capabilities, etc.) and sending it to the gNB together with the Initial Context Establishment Request. The gNB then activates AS security with the UE, which is performed by the gNB sending a SecurityModeCommand message to the UE and by the UE responding to the gNB with a SecurityModeComplete message. Thereafter, the gNB performs reconfiguration to set up signaling radio bearer 2 SRB2 and data radio bearer DRB by transmitting an RRCReconfiguration message to the UE and receiving an RRCReconfigurationComplete from the UE by the gNB in ​​response. For signaling-only connections, the steps related to RRCReconfiguration are skipped since SRB2 and DRBs are not set up. Finally, the gNB notifies the AMF that the setup process is complete with an INITIAL CONTEXT SETUP RESPONSE.

[0101] Therefore, in the present disclosure, an entity of 5GC (e.g., AMF, SMF, etc.) is provided, which includes a circuit for establishing a next generation (NG) connection with a gNodeB in operation; and a transmitter, which sends an initial context establishment message to the gNodeB via the NG connection to cause a signaling radio bearer establishment between the gNodeB and the user equipment (UE). In particular, the gNodeB transmits RRC signaling containing a resource allocation configuration information element (IE) to the UE via the signaling radio bearer. Then, the UE performs uplink transmission or downlink reception based on the resource allocation configuration.

[0102] IMT usage scenarios in 2020 and beyond

[0103] Figure 4 Some use cases for 5G NR are shown. In the 3rd Generation Partnership Project New Radio (3GPP NR), three use cases that have been envisioned for IMT-2020 to support a wide variety of services and applications are being considered. The specification of Phase 1 for enhanced mobile broadband (eMBB) has been finalized. In addition to further extending eMBB support, current and future work will also involve standardization of ultra-reliable and low-latency communications (URLLC) and massive machine-type communications. Figure 4 Some examples of envisaged usage scenarios for IMT for 2020 and beyond are shown (see for example ITU-R M.20183 Figure 2 ).

[0104] URLLC use cases have stringent requirements on capabilities such as throughput, latency, and availability, and have been envisioned as one of the enablers of future vertical applications such as wireless control of industrial manufacturing or production processes, telemedicine surgery, distribution automation in smart grids, transportation safety, etc. The ultra-reliability of URLLC will be supported by identifying technologies that meet the requirements set by 3GPP TR 38.913 version 16.0.0. For NR URLLC in Release 15, the key requirements include a target user plane latency of 0.5ms for UL (uplink) and a target user plane latency of 0.5ms for DL ​​(downlink). The general URLLC requirement for one transmission of a packet is a BLER (block error rate) of 1E-5 for a packet size of 32 bytes, with a user plane latency of 1ms.

[0105] From a physical layer perspective, reliability can be improved in a number of possible ways. The current scope for improving reliability involves defining a separate CQI table for URLLC, a more compact DCI format, repetition of PDCCH, etc. However, as NR becomes more stable and developed (a key requirement for NR URLLC), the scope for achieving ultra-reliability may widen. Specific use cases for NR URLLC in Rel.15 include augmented reality / virtual reality (AR / VR), e-health, e-safety, and mission-critical applications.

[0106] In addition, the technical enhancements targeted by NR URLLC are aimed at delay improvement and reliability improvement. Technical enhancements for delay improvement include configurable parameter sets, non-slot-based scheduling with flexible mapping, unlicensed (configured licensed) uplinks, slot-level repetitions for data channels, and downlink preemption. Preemption means stopping the transmission for which resources have been allocated, and the allocated resources are used for another transmission that has been requested later, but with lower latency / higher priority requirements. Therefore, the authorized transmission is preempted by the later transmission. Preemption can be applied independently of a specific service type. For example, a transmission for service type A (URLLC) can be used for transmission preemption of service type B (such as eMBB). Technical enhancements for reliability improvement include a dedicated CQI / MCS table for a target BLER of 1E-5.

[0107] The use case of mMTC (Massive Machine Type Communications) is characterized by a very large number of connected devices that typically send relatively small amounts of non-delay sensitive data. The devices are required to be low-cost and have very long battery life. From the NR perspective, utilizing very narrow bandwidth portions is a possible technical solution to save power from the UE's perspective and achieve long battery life.

[0108] As mentioned above, the range of reliability in NR is expected to widen. A key requirement in all cases (especially required for URLLC and mMTC) is high reliability or ultra-reliability. Several mechanisms can be considered to improve reliability from a radio perspective and a network perspective. In general, there are several key potential areas that can help improve reliability. These areas include compact control channel information, data / control channel repetition, and diversity with respect to frequency, time and / or spatial domains. These areas are generally applicable to reliability, regardless of the specific communication scenario.

[0109] For NR URLLC, further use cases with more stringent requirements have been identified, such as factory automation, transportation industry and power distribution. The more stringent requirements are higher reliability (up to 10 6 level), higher availability, packet sizes up to 256 bytes, time synchronization down to the order of a few μs, where the value can be one or a few μs, depending on the frequency range, and short latency of around 0.5 to 1 ms, in particular a target user plane latency of 0.5 ms, depending on the use case.

[0110] In addition, for NR URLLC, several technical enhancements from a physical layer perspective have been identified. These include PDCCH (Physical Downlink Control Channel) enhancements related to compact DCI, PDCCH repetition, and increased PDCCH monitoring. In addition, UCI (Uplink Control Information) enhancements are related to enhanced HARQ (Hybrid Automatic Repeat Request) and CSI feedback enhancements. In addition, PUSCH enhancements related to mini-slot level hopping and retransmission / repetition enhancements have been identified. The term "mini-slot" refers to a transmission time interval (TTI) that includes a smaller number of symbols than a slot (a slot including fourteen symbols).

[0111] QoS Control

[0112] The 5G QoS (Quality of Service) model is based on QoS flows and supports both QoS flows that require guaranteed flow bit rate (GBR QoS flows) and QoS flows that do not require guaranteed flow bit rate (non-GBR QoS flows). At the NAS level, QoS flows are therefore the finest granularity of QoS differentiation within a PDU session. QoS flows are identified within a PDU session by the QoS Flow ID (QFI) carried in the encapsulation header on the NG-U interface.

[0113] For each UE, the 5GC establishes one or more PDU Sessions. For each UE, the NG-RAN establishes at least one Data Radio Bearer (DRB) together with the PDU Session and may subsequently configure one or more additional DRBs for one or more QoS Flows of that PDU Session (depending on when the NG-RAN does so), e.g. as described above with reference to Figure 3 As shown in Figure 2. NG-RAN maps packets belonging to different PDU sessions to different DRBs. NAS-level packet filters in UE and 5GC associate UL and DL packets with QoS flows, while AS-level mapping rules in UE and NG-RAN associate UL and DL QoS flows with DRBs.

[0114] Figure 5 The 5G NR non-roaming reference architecture is shown (see, e.g., 3GPP TS 23.501, e.g., v16.9.0 or v17.4.0, section 4.2.3). Figure 4 The application function (AF) (e.g., an external application server hosting 5G services) described in the exemplary embodiment interacts with the 3GPP core network to provide services, such as to support the impact of applications on service routing, access network exposure functions (NEFs), or interact with a policy framework for policy control (e.g., QoS control) (see Policy Control Function, PCF). Based on operator deployment, application functions that are considered to be trusted by the operator may be allowed to interact directly with related network functions. Operators do not allow application functions that directly access network functions to interact with related network functions using an external exposure framework via NEF.

[0115] Figure 5 Other functional units of the 5G architecture are shown, namely, the network slice selection function (NSSF), the network repository function (NRF), the unified data management (UDM), the authentication server function (AUSF), the access and mobility management function (AMF), the session management function (SMF) and the data network (DN), such as operator services, Internet access or third-party services. All or part of the core network functions and application services can be deployed and run on a cloud computing environment.

[0116] Therefore, in the present disclosure, an application server (e.g., AF of a 5G architecture) is provided, which includes a transmitter and a circuit, which in operation sends a request containing QoS requirements of at least one of URLLC, eMBB, and mMTC services to at least one of the functions of 5GC (e.g., NEF, AMF, SMF, PCF, UPF, etc.) to establish a PDU session including a radio bearer between a gNodeB and a UE according to the QoS requirements, and the circuit in operation uses the established PDU session to perform the service.

[0117] Cell types in 5G NR

[0118] There are several types of cells in 5G NR, including PCell, SCell, PSCell, and SpCell.

[0119] PCell is a primary cell, which can be used to initiate initial access.

[0120] SCell is a secondary cell. A UE may be configured with one or more SCells in connected mode. SCells may be activated or deactivated, for example, according to a service.

[0121] The PSCell is closely connected to Dual Connectivity (DC). E-UTRAN supports Dual Connectivity (DC) operation, whereby a multi-Rx / Tx UE in RRC_CONNECTED can be configured to utilize radio resources provided by two different schedulers located in two nodes (primary node, secondary node) connected via a non-ideal backhaul on the X2 interface. The primary node provides a control plane connection to the core network. The secondary node will not have a control plane connection to the core network, but will provide additional resources to the UE in the case of MR-DC.

[0122] In dual connectivity, there are two groups of cells, the primary cell group (MCG) and the secondary cell group (SCG). In the MCG, there can be one PCell and one or more SCells. In the SCG, there can be one PSCell and one or more SCells. The UE performs initial access under the SCG via the PSCell. Since most signaling messages are only sent on the PCell and PSCell, 3GPP also defines the concept of SpCell (special cell) for ease of description, which should be understood as SpCell = PCell + PSCell.

[0123] Figure 6 An overview of different cell types in dual connectivity is shown.

[0124] In addition, there may be Multi-Radio Dual Connectivity (MR-DC). With MR-DC, the primary RAN node acts as the control entity, utilizing the secondary RAN for additional data capacity. Example MR-DC configurations include EN-DC (E-UTRA-NR Dual Connectivity), NR-DC (New Radio Dual Connectivity), NGEN-DC (NG-RAN-E-UTRA Dual Connectivity), and NE-DC (NR-E-UTRA Dual Connectivity).

[0125] TS 37.340 v17.1.0 defines multi-radio dual connectivity in Section 4. Conditional PSCell Addition (CPA) and Conditional PSCell Change (CPC) are defined in TS 37.340 as presented in Section 4.5 of TS 38.300 v17.1.0 and will be further explained below.

[0126] Switching process

[0127] Typical and simplified switching in Figure 7 , and briefly explained below. A handover of a UE involves a decision by the source base station whether to handover the UE from a source / serving gNB to a neighbor / target gNB (target radio cell). This decision is typically made by the source gNB, for example based on measurement results from the UE. The measurement results may be carried in one or more measurement reports, for example in Figure 7 The measurement report is sent by the UE to assist the source cell in the handover process.

[0128] The handover is then prepared between the two involved base stations (preparation phase), that is, the source base station (which may be used interchangeably herein with source gNB, source cell) and the target base station (which may be used interchangeably herein with target gNB, target cell). The source gNB may transmit a handover request message to the target base station, which in turn may respond with a handover request confirm message, in order to implement the preparation phase. Such a preparation phase allows the neighboring cell to decide whether it has the capability to accept another UE (e.g., confirm the handover) and reserve resources for the UE to be handed over.

[0129] Then, in the execution phase, the UE is instructed to switch from the source cell to the target cell by a handover command message (e.g., an RRCReconfiguration message), which involves, for example, reconfiguration of the UE's radio resources in order to establish a connection with the target base station of the target radio cell. The UE performs the reconfiguration accordingly and attaches to the new target base station, which includes synchronization and performing (e.g., contention-free) random access procedures. For example, synchronization may include the UE acquiring synchronization signals (e.g., primary synchronization signal PSS and secondary synchronization signal SSS) that are typically used to obtain the cell identity and frame timing of the target cell, thereby achieving time and frequency synchronization. The random access procedure is performed by the UE, for example, in order to obtain a timing advance value and obtain uplink resources for uplink transmission using a RAR message. For example, it at least includes sending a RACH preamble (e.g., a dedicated preamble, consistent with 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 finally as the third and last step of the random access procedure, the UE confirms that the reconfiguration of and access to the target cell has been completed by sending a handover confirmation message (RRCReconfigurationComplete message) to the target gNB.

[0130] An exemplary implementation of such a handover procedure is defined for RRC connection mobility for 5G NR in 3GPP technical standard TS 38.300 v17.1.0, section 9.2.3.2.

[0131] The handover command message may include information of the target cell, such as a target cell ID and configuration information capable of connecting to the target cell, and handover acceptance and handover rejection conditions.

[0132] As an exemplary and simplified overview, the RRCReconfiguration message may contain one or more of the following:

[0133] Target cell ID

[0134] New C-RNTI

[0135] Target gNB security algorithm identifier for the selected security algorithm

[0136] Dedicated RACH resources

[0137] Public RACH resources

[0138] Association between RACH resources and SSB

[0139] System information of the target cell

[0140] According to a more detailed exemplary definition of the possible contents of the handover command message, 5G NR defines the RRCReconfiguration message of Section 6.2.2 of 3GPP TS38.331v17.1.0. According to 5G, the RRCReconfiguration message is a command to modify the RRC connection. It can transmit information for measurement configuration, mobility control, radio resource configuration (including RBs (radio bearers), MAC (medium access control) main configuration and physical channel configuration) and AS (access layer) security configuration.

[0141] Conditional Switching - CHO

[0142] In the conventional handover procedure presented above, the gNB is responsible for making the decision whether a handover should be performed. This handover procedure is a reactive procedure and is prone to handover failures. For example, it may happen that when the radio link becomes degraded and the mobile terminal needs to send a measurement report, the measurement report never reaches the network. Or, even so, 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 so large that it requires multiple transmissions.

[0143] An important mobility enhancement specified by 3GPP in Rel-16, named "Conditional Handover (CHO)", focuses on reducing the number of failures that occur when a user is mobile, for example, when a handover between cells fails or when a connection fails even before a handover (HO) is triggered. CHO therefore improves mobility robustness to handovers. Furthermore, it allows for reduced signaling and reduced handover latency. CHO can be used to change the PCell, both for UEs without dual connectivity and for the primary cell group for UEs with dual connectivity. In DC (dual connectivity), a PCell change procedure can be performed to change the PCell of the primary cell group.

[0144] Due to its usefulness, CHO has been considered for use in many areas where cellular communications are applied, including, for example, mobile broadband (MBB), non-terrestrial networks (NTN), integrated access backhaul, and NR unlicensed.

[0145] In conditional handover, the mobile terminal receives a handover command from the source gNB (which is, for example, an RRCReconfiguration message containing conditional configuration information prepared by the target candidate cell). Upon receiving the handover command, the mobile terminal stores the configuration of the handover command instead of applying it immediately as in conventional handover. Together with the handover command, the mobile terminal also receives the relevant conditions to be monitored by the mobile terminal. The mobile terminal applies the stored command only when the conditions are met. The mobile terminal then performs the handover and connects to the target node, as in normal handover.

[0146] In one example, the source gNB may be responsible for preparing the conditional handover, including the execution conditions regarding when the UE should perform (i.e., trigger) CHO. On the other hand, the candidate target gNB provides the CHO configuration parameters to be forwarded by the source gNB to the mobile terminal.

[0147] Figure 8 The signaling diagram of FIG. 1 illustrates an exemplary and basic CHO procedure. As is apparent therefrom, the source gNB prepares for a CHO 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, which includes 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 a conventional handover), but rather the UE continues to exchange 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 initiates the CHO execution (e.g., in the same or similar manner as in a conventional handover).

[0148] According to an example, the configuration parameters of the target gNB may include one or more of the following:

[0149] The radio resource configuration of the candidate target cell, such as resource blocks, physical channel configuration,

[0150] ·Security configuration of candidate target cells,

[0151] Dual connection information, such as primary cell group information, secondary cell group information,

[0152] · Measurement configuration of candidate target cells,

[0153] • Mobility information (including, for example, handover configuration and conditional configuration).

[0154] Fig. 9 The signaling diagram of FIG. 1 shows another exemplary and simplified CHO process, which is similar to Figure 8The basic signaling diagram of FIG. 17 has more details than that of FIG. 17 . As is apparent therefrom, the source gNB prepares for CHO, for example based on measurements received from the mobile terminal. Therefore, the source gNB identifies gNB1 as a potential target for CHO and sends a handover request (here a CHO Request) to the target gNB (e.g., in 5G, e.g., according to TS 38.423 v17.1.0, the corresponding CHO-related IE in the handover request message is an IE Conditional Handover Information Request). The target gNB processes the received handover request (e.g., performs admission control) and, assuming that the target gNB allows the mobile terminal to access its 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 of the requested target cell ID and the maximum number of CHO preparations (see TS 38.423 v17.1.0, section 9.1.1.2). Typically, the CHO ACK message may include necessary configuration information for accessing the target cell (eg, in the form of a Handover Request Acknowledgement message, such as an XnAp, Xn Application Protocol, signaling message according to 3GPP standard TS 38.423).

[0155] In this example implementation, it is assumed that the source gNB determines the appropriate CHO execution conditions upon receiving a CHO ACK from the target cell.

[0156] The source gNB then sends a CHO configuration to the mobile terminal, including, for example, configuration information for accessing the target cell (received by the source gNB from the target gNB) and the determined CHO execution condition, both of which are stored by the mobile terminal. The mobile terminal is thus provided with the necessary information to be able to perform a conditional handover. For example, the UE may store the CHO information in a memory.

[0157] Accordingly, the mobile terminal does not perform handover immediately, but first maintains the connection with the source gNB and starts evaluating the CHO execution conditions for the target cell.

[0158] When the CHO execution conditions are finally met, the UE performs a handover to the target cell, which involves, for example, detaching the UE from the source gNB, applying the stored configuration corresponding to the target cell, synchronizing to the target cell and completing the handover (e.g., by 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 Fig. 9 An exemplary implementation is another XnAp message, such as a handover success signaling message of 3GPP TS 38.423.

[0159] There are several options on how to implement the conditions for CHO. It is assumed that the conditions define criteria for when to apply a stored handover command, where the criteria are based on, for example, the quality of the serving cell and neighboring cells (somewhat similar to the conditions that cause 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 a CHO towards the target cell.

[0160] For example, when a neighboring cell becomes a better offset than the serving cell (e.g., similar to event A3), or when the serving cell becomes worse than a first threshold and the neighboring cell becomes between a second threshold (e.g., similar to event A5), the network may configure the wireless terminal to perform CHO. Measurements for determining cell quality may be based on, for example, measurements such as radio signal received power RSRP and quality represented by radio signal received quality RSRQ and signal to interference and noise ratio SINR. Two (or more) (sub) conditions may also be configured for the mobile terminal, and these multiple (sub) conditions may be associated with a stored command, i.e., the command is applied only when all (sub) conditions are met.

[0161] As another exemplary embodiment of CHO, if the UE is configured with CHO configuration and receives another (legacy) HO command from the gNB before the CHO execution conditions are met, the UE will perform handover based on the received (legacy) HO command and will not wait for any CHO conditions to be met. In short, legacy handover takes precedence over CHO.

[0162] According to an exemplary embodiment, the CHO configuration shown includes the configuration of CHO candidate cells (generated by the candidate gNB) and the corresponding execution conditions (generated by the source gNB). For example, the configuration of the CHO candidate cells may include, for example, a list of candidate cells with corresponding cell IDs and the carrier frequencies of the candidate cells. The execution conditions may include CHO-related triggering events, such as the above-mentioned A3 / A5 events, and trigger quantities (e.g., RSRP and RSRQ, RSRP and SINR, etc.).

[0163] An exemplary 5G-compatible implementation of conditional switching will be briefly explained below, with more details available from the 3GPP technical standards, including, for example, TS 38.331v17.1.0, 38.300v17.1.0, and 38.423v17.1.0.

[0164] TS 38.331 defines the RRCReconfiguration procedures and messages used as part of CHO and the corresponding UE behaviors, for example in 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 TS38.331 and is used by the network to configure the UE with one or more candidate SpCells. The network provides the configuration parameters of the target SpCell in the ConditionalReconfiguration IE as part of the RRCReconfiguration IE. The ConditionalReconfiguration IE provides the configuration and execution conditions of the candidate target SpCells for conditional switching, conditional PSCell addition (CPA, see later discussion) and conditional PSCell change (CPC, see later discussion).

[0165] ConditionalReconfiguration

[0166] IE ConditionalReconfiguration is used to add, modify, and release conditional reconfiguration configurations.

[0167] ConditionalReconfiguration Information Elements

[0168]

[0169]

[0170]

[0171] CondReconfigToAddModList

[0172] IE CondReconfigToAddModList refers to a list of condition reconfigurations to be added or modified, where for each entry, the condReconfigId and the associated condExecutionCond / condExecutionCondSCG and CondRcreconfig.

[0173] CondReconfigToAddModList Information Element

[0174]

[0175]

[0176]

[0177] CondReconfigId

[0178] IE CondReconfigId is used to identify the CHO, CPA or CPC configuration.

[0179] CondReconfigId Information Element

[0180]

[0181] In addition, TS 38.331 defines in section 6.3.2 a ReportConfigNR IE which specifies criteria for triggering a CHO, CPA or CPC event.

[0182] TS 38.300 defines conditional handover in Section 9.2.3.4 as a handover performed by the UE when one or more handover execution conditions are met. The UE starts evaluating the execution condition(s) upon receiving the CHO configuration and stops evaluating the execution condition(s) once the handover is performed. In addition, the execution condition may 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.) may be configured simultaneously for evaluating the CHO execution condition of a single candidate cell. Section 16.4.3.2.2 explains CHO applied to non-terrestrial networks.

[0183] As an exemplary possibility for general conditional handover, instead of preparing only one target cell as in the conventional case, multiple candidate target cells may be pre-prepared in the network. This may be advantageous since the specific target cell to be accessed by the mobile terminal is uncertain due to delayed handover. Accordingly, the mobile terminal receives various target cell configurations and (one or more) CHO trigger conditions for each target cell configuration to be monitored. When the conditions of one of the configured candidate target cells are met, the mobile terminal performs a handover to the target node based on the target cell configuration that has been received.

[0184] Fig.10 , CHO for a scenario with more than one candidate target cell (here, two candidate target cells, gNB1 and gNB2, respectively) is shown in FIG. Fig.10 is with Fig. 9 The signaling diagram is similar to the signaling diagram for the scenario with only one candidate target cell provided in . The signaling diagram is largely similar to Fig. 9The same. One exception is that CHO preparation is performed for two candidate target cells controlled by gNB1 and gNB2 respectively. Fig.10 Obviously, the CHO preparation including CHO request and CHO ACK is shown in a simplified manner as arrows on both sides of the two candidate target cells of gNB1 and gNB2.

[0185] The source gNB determines the CHO execution conditions of each candidate target cell accordingly, and provides the mobile terminal with the CHO configurations of the two candidate target cells and their respective CHO execution conditions.

[0186] Furthermore, it is exemplarily assumed that the source gNB sends two CHO configurations for two candidate target cells to the UE together with the corresponding CHO execution conditions for each CHO configuration. Alternatively, these may be sent to the UE separately for each candidate target cell.

[0187] exist Fig.10 In the scenario, it is exemplarily assumed that the mobile terminal determines that the CHO execution conditions of the target gNB2 are met, and therefore performs switching to the target cell of gNB2.

[0188] Fig.10 The Conditional Handover procedure includes two additional important steps. First, after successfully completing CHO, the UE releases (e.g., deletes from its storage) all CHO configurations and CHO execution conditions, including those of candidate target cells of gNB1 that did not trigger CHO to it. Second, the source gNB informs gNB1 that the CHO for the mobile terminal is cancelled upon receipt of a CHO Execution Indication message from the target cell gNB2. This allows gNB1 to release any resources that may have been reserved for a potential CHO to the mobile terminal.

[0189] Conditional PSCell changes

[0190] 3GPP Release 16 also introduces the Conditional PSCell Change Procedure (CPC) to improve the mobility robustness of PSCell changes in dual connectivity scenarios.

[0191] In DC (dual connectivity, such as MR-DC), a PSCell change procedure may 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.

[0192] Similar to CHO, the execution condition PSCell changes (CPC) only when the corresponding CPC execution condition is met.

[0193] CPC reuses much of the functionality of the conditional switching discussed above (see 10.1 of TS 37.340 v17.1.0).

[0194] If SRB3 is not configured, the UE completes the CPC execution process through a ULInformationTransferMRDC message to the master node (MN) (MCG), which includes an embedded RRCReconfigurationComplete message to the new PSCell; otherwise, the UE sends an RRCReconfigurationComplete message directly to the new PSCell.

[0195] TS 37.340v17.1.0 defines an exemplary 5G-compatible implementation, and TS 37.340v17.1.0 provides details of CPC in its section 10.6, as shown below.

[0196] The CPC configuration contains the configuration and execution conditions of CPC candidate PSCells, and may contain the MCG configuration of the inter-SN CPC to be applied when CPC execution is triggered.

[0197] The execution conditions may consist of, for example, one or two trigger conditions (CondEvents, as defined in TS 38.331 or TS36.331). Only a single RS (reference signal) type and at most two different trigger quantities (e.g., RSRP and RSRQ, RSRP and SINR, etc.) may be used to evaluate the CPC execution conditions for a single candidate PSCell.

[0198] Before any CPC execution conditions are met, upon receiving a PSCell Change Command or PCell Change Command, the UE performs the PSCell Change procedure as described in clauses 10.3 and 10.5 or the PCell Change procedure as described in clause 9.2.3.2 of TS 38.300 or clause 10.1.2.1 of TS 36.300, regardless of any previously received CPC configuration.

[0199] When executing CPC, the UE is not required to continue evaluating the execution conditions of other candidate PSCells.

[0200] Once the CPC procedure is successfully performed, the UE releases all stored conditional reconfigurations (eg, for CPC and for CHO as specified in TS 38.300 or TS 36.300).

[0201] When releasing the SCG, the UE also releases the stored CPC configuration.

[0202] In Release 16, the CPC procedure is limited to intra-SN changes without MN involvement. 3GPP Release 17 introduces support for inter-SN Conditional PSCell Change (CPC).

[0203] Fig.11 An exemplary and simplified signaling diagram of the CPC procedure is shown in . As is apparent therefrom, the source gNB prepares CPCs with candidate target cells of both gNB1 and gNB2, respectively. This may, for example, involve receiving CPC configuration parameters of gNB1 and gNB2, respectively, at the source gNB, and determining CPC execution conditions for each of the two CPC candidates by the source gNB. The two CPC configurations (including CPC configuration parameters and respective CPC execution conditions) are then transmitted from the source gNB to the UE. The UE does not immediately change the PSCell to one of the two candidate target cells, but rather evaluates the CPC execution conditions of the two candidates. Ultimately, the UE determines that the CPC execution conditions for the target gNB2 are met, and changes the PSCell to the cell of gNB2. Upon successful completion of the CPC, the UE releases the two CPC configurations, including one CPC configuration for gNB1 for which CPC was not performed.

[0204] Conditional PSCell Addition

[0205] 3GPP also introduced the conditional PSCell addition procedure (CPA) to improve mobility robustness when creating a new secondary cell group. According to CPA, a PSCell is added to the secondary cell group in a dual connectivity scenario, and the UE is connected to the new PSCell of the SCG in addition to the cells of the MCG. In one example, the additional PSCell may be another radio access technology that is different from the current (one or more) radio access technologies. CPA can also be used to add another SCell to the SCG. In addition, under dual connectivity, there can be multiple SCGs established for the UE, although only one SCG can be active at a given point in time. Therefore, CPA can also be used to create another SCG with another PSCell, even if the other SCG is inactive at the beginning.

[0206] Similar to CHO, conditional PSCell addition (CPA) is defined as a PSCell addition performed by the UE only when the corresponding CPA execution condition is met. The UE starts evaluating (one or more) execution conditions when receiving the CPA configuration, and stops evaluating (one or more) execution conditions once the PSCell addition or PCell change is triggered.

[0207] CPA reuses much of the functionality of the conditional switch discussed above (see 10.1 of TS 37.340 v17.1.0).

[0208] In an exemplary embodiment, the CPA procedure is used to establish a connection between the UE and an additional PSCell of a newly created SCG, including configuration parameters of the PSCell.

[0209] TS 37.340v17.1.0 discloses conditional PSCell addition in Section 10.2.3 as part of the secondary node addition in Section 10.2. According to this exemplary 5G-compatible implementation, the CPA configuration contains the configuration of the CPA candidate PSCell, the execution conditions, and may contain the MCG configuration to be applied when CPA execution is triggered. The execution conditions may consist of one or two trigger conditions (CondEvents, as defined in TS 38.331[4] or TS 36.331

[10] ). Only a single RS type and at most two different trigger quantities (e.g., RSRP and RSRQ, RSRP and SINR, etc.) may be used to evaluate the CPA execution conditions for a single candidate PSCell.

[0210] Before any CPA execution conditions are met, and upon receiving a normal (i.e., unconditional) PSCell Addition Command or PCell Change Command, the UE performs a PSCell Addition procedure as described in clauses 10.2.1 or 10.2.2, or a PCell Change procedure as described in clauses 9.2.3.2 of TS 38.300 or clause 10.1.2.1 of TS 36.300, regardless of any previously received CPA configuration. Upon successful completion of the PSCell Addition procedure or PCell Change procedure, the UE releases the stored CPA configuration.

[0211] When performing CPA, the UE is not required to continue evaluating the execution conditions of other candidate PSCells.

[0212] Once the CPA procedure is successfully performed, the UE releases all stored conditional reconfigurations (i.e. for CPA and for CHO as specified in TS 38.300 or TS 36.300). CPA configuration in HO command, in PSCell add command or in conditional configuration (i.e. CPA, CPC or CHO configuration) is not supported.

[0213] Fig.12An exemplary and simplified signaling diagram of the CPA procedure is shown in . As is apparent therefrom, the source gNB (which can therefore be considered as a cell of the primary cell group) prepares CPA with candidate target cells of both gNB1 and gNB2, respectively. This may, for example, involve receiving CPA configuration parameters of gNB1 and gNB2, respectively, at the source gNB, and determining CPA execution conditions for each of the two CPA candidates by the source gNB. The two CPA configurations (including CPA configuration parameters and respective CPA execution conditions) are then transmitted from the source gNB to the UE. The UE does not immediately add the PSCell of gNB1 or gNB2, but evaluates the CPA execution conditions of the two candidates. Ultimately, the UE determines that the CPA execution conditions of the target gNB2 are met, and creates an SCG with the PSCell of gNB2. Upon successful completion of the CPA, the UE releases the two CPA configurations, including one CPA configuration for gNB1 for which the CPA was not performed.

[0214] Further Improvements

[0215] In the above, we have discussed the mobility enhancements for CHO, CPC and CPA introduced in 3GPP Releases 16 and 17. In Release 18, further enhancements to NR mobility are envisaged.

[0216] The inventors have identified problems in the current definitions of CHO, CPC and CPA procedures. In particular, the current Release 16 and 17 NR specifications require the UE to release the CHO / CPC / CPA configuration upon successful completion of the corresponding procedure, respectively.

[0217] For example, Fig.10 As shown, upon successful completion of CHO, the UE releases all CHO configurations, including CHO configuration parameters and CHO execution conditions.

[0218] like Fig.11 As shown, upon successful completion of CPC, the UE releases all CPC configurations, including CPC configuration parameters and CPC execution conditions.

[0219] like Fig.12 As shown, upon successful completion of CPA, the UE releases all CPA configurations, including CPA configuration parameters and CPA execution conditions.

[0220] Therefore, the network and the UE need to perform reconfiguration and reinitialization for CHO / CPC / CPA so as to be able to perform another subsequent CHO / CPC / CPA, as respectively combined with the above Fig.10 , 11 , as explained in 12.

[0221] This results in an increase in 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.

[0222] Furthermore, this may result in increased delays in the CHO / CPC / CPA procedure, since the UE needs to be configured first after a previous successful CHO / CPC / CPA, before being able to perform CHO / CPC / CPA.

[0223] The above disadvantages are particularly severe in case of frequent cell changes, for example, when operating in FR2 (which includes the frequency band from 24.25 GHz to 71.0 GHz).

[0224] Therefore, the inventors have identified the possibility of providing an improved mobility procedure (such as CHO, CPC, CPA) allowing to avoid one or more of the above mentioned disadvantages. The present invention relates to different solutions and variants for such an improved mobility procedure.

[0225] Example

[0226] In the following, UE, base station and corresponding processes that meet these requirements will be described for new radio access technologies envisioned for 5G mobile communication systems, but these new radio access technologies can also be used in previous LTE mobile communication systems or future mobile communication systems. Different implementations and variants will also be explained. The following disclosure is facilitated by the discussions and findings described above and may, for example, be based on at least a portion thereof.

[0227] Generally, it should be noted that many assumptions have been and are made herein so that the basic principles of the present disclosure can be explained in a clear, concise and understandable manner. However, these assumptions should only be understood as examples made herein for illustrative purposes, which are not necessarily necessary for the present invention and therefore should not limit the scope of the present disclosure. Those skilled in the art will appreciate that the principles disclosed below and as set forth in the claims can be applied to different scenarios and in ways not explicitly described herein.

[0228] In addition, some of the terms for processes, entities, layers, etc. used below are closely related to the terms used in LTE / LTE-A systems or the current 3GPP 5G standardization, even though the specific terms used in the context of new radio access technologies for the next communication system have not yet been fully decided or may eventually change. Therefore, the terms may change in the future without affecting the functions of the corresponding features and embodiments. Therefore, those skilled in the art realize that the embodiments and their scope of protection should not be limited to the specific terms used exemplarily herein due to the lack of updated or finally agreed terms, but should be understood more broadly in terms of the functions and concepts that form the basis of the technical solutions explained in the present disclosure.

[0229] For example, a mobile station or mobile node or user terminal or user equipment (UE) is a physical entity (physical node) within 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 through which the node can communicate. Similarly, a network entity may have a logical interface that attaches a functional entity to a communication facility or medium through which the network entity can communicate with other functional entities or communication nodes.

[0230] The term "base station" or "radio base station" here refers to a physical entity within a communication network. Like 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. The physical entity performs some control tasks regarding the communication device, including one or more of scheduling and configuration. Note that the base station functionality and the communication device functionality can also be integrated into a single device. For example, a mobile terminal can also implement the functionality of a base station for other terminals. The term used in LTE is eNB (or eNodeB), while the term currently used for 5G NR is gNB. Moreover, the base station can also be a gNB in ​​a non-terrestrial network (NTN) NR system.

[0231] The communication between a UE and a base station is generally standardized and may be defined by different layers such as PHY, MAC, RRC, etc. (see the background discussion above).

[0232] The expression "cell configuration" here can be understood as a configuration for a cell that is available in the context of performing a cell mobility procedure (e.g., CHO, CPC, or CPA procedure). In an exemplary embodiment, the cell configuration includes a complete set of parameters for the cell and an "execution condition" to restrict the execution of the cell mobility procedure to the satisfaction of the condition.

[0233] The expression "cell configuration parameters" may be understood as parameters related to a cell (more precisely, a candidate target cell), wherein these parameters may be used for performing a conditional cell mobility procedure with said cell.

[0234] The expression "candidate target cell" may be understood to refer to a cell that is a candidate target for the conditional cell mobility procedure. There may be one or more candidate target cells, and one of these candidate target cells may eventually become the actual target cell of the conditional cell mobility procedure.

[0235] The expression "conditional cell mobility procedure" may be understood to cover mobility procedures related to different cells, the execution of which is not immediate but depends on the fulfillment of an execution condition. Examples of conditional cell mobility procedures are conditional handover (CHO, see e.g. the 5G standardized CHO discussed above), conditional cell change (CPC, see e.g. the 5G standardized CPC discussed above) or conditional cell addition (CPA, see e.g. the 5G standardized CPA discussed above).

[0236] The term "release", for example in connection with releasing a configuration, may for example be understood as "delete", for example delete a (stored) configuration.

[0237] For example, the term "maintain" in relation to a maintain configuration may be understood as configured not to release, such as a non-releasing configuration.

[0238] Fig.13 A general, simplified and exemplary block diagram of a user equipment (also referred to as a communication device) and a scheduling device (here exemplarily assumed to be located in a base station, such as an LTE eNB (alternatively referred to as ng-eNB) or a gNB in ​​5G NR) is shown. The UE and the eNB / gNB communicate with each other via a (wireless) physical channel using a transceiver, respectively.

[0239] The communication device may include a transceiver and a processing circuit. The transceiver may include and / or be used as a receiver and a transmitter. The processing circuit may be one or more hardware, such as one or more processors or any LSI. There is an input / output point (or node) between the transceiver and the processing circuit, and the processing circuit may control the transceiver through the input / output point (or node), that is, control the receiver and / or transmitter and exchange receive / transmit data. The transceiver as a transmitter and receiver may include an RF (radio frequency) front end, which includes one or more antennas, amplifiers, RF modulators / demodulators, etc. The processing circuit may implement control tasks, such as controlling the transceiver to send user data and control data provided by the processing circuit and / or receiving user data and control data further processed by the processing circuit. The processing circuit may also be responsible for executing other processes, such as determining, deciding, calculating, measuring, etc. The transmitter may be responsible for executing the sending process and other processes related thereto. The receiver may be responsible for executing the receiving process and other processes related thereto, such as monitoring channels.

[0240] Different technical solutions for the improved mobility process are described below. In the connection, an improved UE, an improved base station and an improved integrated circuit are proposed, which participate in the improved mobility process individually or together. Corresponding methods for UE behavior and base station behavior are also provided. The integrated circuit corresponds to the UE and the base station, and corresponds to their behaviors respectively.

[0241] Two technical solutions will be proposed for the improved mobility process. Figures 14 to 23 Discuss the first technical solution and refer to Figure 24 to Figure 28 Discuss the second technical solution (refer to Fig.21 explanation).

[0242] The first technical solution

[0243] Fig.14 A simplified and exemplary UE structure of an exemplary implementation of an improved mobility process according to the first technical solution is shown, which can be based on the combination of Fig.13 The general UE structure explained is implemented. Fig.14 The various structural elements of the UE shown in the figure may be interconnected with each other, for example using corresponding input / output nodes (not shown), for example, to exchange control and user data and other signals. Although not shown for illustrative purposes, the UE may include further structural elements.

[0244] As from Fig.14 Obviously, the UE may include a cell configuration receiver (used to receive a plurality of cell configurations including cell configuration parameters and execution conditions), an execution condition evaluation circuit and a conditional cell mobility procedure circuit.

[0245] In the present case, the receiver of the UE may therefore exemplarily be configured to at least partially perform one or more of the following operations: receive multiple cell configurations for multiple candidate target cells, and further, as will become apparent from the following disclosure, receive an indication as to which subset to use for evaluation, etc.

[0246] In the present case, as will become apparent from the following disclosure, the processing circuitry of the UE may therefore be exemplarily configured to at least partially perform one or more of the following operations: perform a conditional cell mobility procedure when an execution condition is met, evaluate the execution condition, maintain the received multiple cell configurations, etc.

[0247] In the present case, as will become apparent from the following disclosure, the transmitter of the UE may thus exemplarily be configured to at least partially perform one or more of sending a measurement report to a serving cell of the UE, etc.

[0248] An exemplary process as will be further disclosed in more detail below is implemented by a UE comprising the following items. A receiver of the UE receives multiple cell configurations for multiple candidate target cells from a source base station. Each cell configuration includes cell configuration parameters for performing a conditional cell mobility process with a corresponding candidate target cell, and includes an execution condition regarding when to perform the conditional cell mobility process with the corresponding candidate target cell. The multiple cell configurations include a first subset of cell configurations to be evaluated by the UE when connected to the source base station. The multiple cell configurations include a second subset of cell configurations to be evaluated by the UE when connected to a first candidate target cell among the multiple candidate target cells, the first candidate target cell being different from the source cell of the source base station. The circuit of the UE only evaluates the execution conditions of the first subset of cell configurations. When the execution conditions of the cell configurations in the first subset of the evaluated cell configurations are met for the first candidate target cell, the circuit performs the conditional cell mobility process with the first candidate target cell based on the cell configuration parameters of the first candidate target cell.

[0249] The corresponding exemplary method comprises the following steps performed by the UE:

[0250] receiving, from a source base station, a plurality of cell configurations for a plurality of candidate target cells, wherein each cell configuration comprises a cell configuration parameter for performing a conditional cell mobility procedure with a corresponding candidate target cell and comprises an execution condition regarding when to perform the conditional cell mobility procedure with the corresponding candidate target cell,

[0251] wherein the multiple cell configurations include a first subset of cell configurations to be evaluated by the UE when connected to the source base station, wherein the multiple cell configurations include a second subset of cell configurations to be evaluated by the UE when connected to a first candidate target cell among the multiple candidate target cells, the first candidate target cell being different from the source cell of the source base station,

[0252] Only the execution conditions of the first subset of cell configurations are evaluated,

[0253] When an execution condition of a cell configuration in the first subset of the evaluated cell configurations is satisfied for the first candidate target cell, a conditional cell mobility procedure with the first candidate target cell is performed based on the cell configuration parameters of the first candidate target cell.

[0254] Fig.15 A corresponding sequence diagram of exemplary UE behaviors according to the above-mentioned UE and UE method is shown in FIG.

[0255] Therefore, the above-mentioned improved mobility process achieves the purpose and overcomes some of the above-mentioned shortcomings. For example, the improved mobility process involves the UE having multiple cell configurations, including different subsets used in different serving cells. Accordingly, the UE only processes the appropriate subset of the cell configuration for the current serving cell respectively. Since various subsets of the cell configuration to be used in other cells are already available at the UE before the conditional cell mobility process is performed, the improved mobility process allows the subsequent conditional cell mobility process to be accelerated. In addition, since the corresponding subset based on the cell configuration is already available at the UE, the new serving cell does not need to send the appropriate cell configuration to be evaluated by the UE, thereby saving signaling overhead with the UE after the conditional cell mobility process is performed.

[0256] Some exemplary embodiments of the improved mobility procedure also involve improved base stations, in particular an improved source base station to which the UE is currently connected (referred to as, for example, a serving base station, since the base station 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 therein, as will be explained below.

[0257] Fig.16 A simplified and exemplary source base station structure according to an exemplary embodiment of the improved mobility process is shown, which can be based on a combination of Fig.13 The general base station structure explained above is implemented. Fig.16 The various structural elements of the source base station shown in the figure may be interconnected with each other, for example, using corresponding input / output nodes (not shown), for example, to exchange control and user data and other signals. Although not shown for illustrative purposes, the source base station may include additional structural elements.

[0258] As is apparent therefrom, the source base station includes a cell configuration transmitter (initial cell configuration includes cell configuration parameters and execution conditions), a cell configuration preparation circuit.

[0259] In the present case, as will become apparent from the following disclosure, the receiver of the source base station may therefore exemplarily be configured to at least partially perform one or more of the following operations: receive requested cell configuration parameters, etc.

[0260] In the present case, as will become apparent from the following disclosure, the processing circuitry of the source base station may therefore exemplarily be configured to at least partially perform one or more of the following operations: generate multiple cell configurations, and determine cell configuration parameters for each candidate target cell, etc.

[0261] In the present case, as will become apparent from the following disclosure, the transmitter of the source base station may therefore be exemplarily configured to at least partially perform one or more of the following operations: sending a cell configuration to the UE, sending a request to a candidate target cell to request cell configuration parameters, etc.

[0262] An exemplary process as will be disclosed in further detail below is implemented by a source base station comprising the following items. Circuitry of the source base station generates multiple cell configurations for multiple candidate target cells. Each cell configuration includes cell configuration parameters for performing a conditional cell mobility procedure between a user equipment UE and the corresponding candidate target cell, and includes an execution condition regarding when to perform the conditional cell mobility procedure with the corresponding candidate target cell. The multiple cell configurations include a first subset of cell configurations to be evaluated by the UE when connected to the base station. The multiple cell configurations include a second subset of cell configurations to be evaluated by the UE when connected to a first candidate target cell among the multiple candidate target cells, the first candidate target cell being different from the source cell of the base station. A transmitter sends the generated multiple cell configurations to the UE.

[0263] The corresponding method comprises the following steps performed by the source base station:

[0264] receiving, from a source base station, a request for requesting a cell configuration parameter 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,

[0265] in response to receiving the request, generating a cell configuration of at least another candidate target cell, wherein the cell configuration of the another candidate target cell comprises cell configuration parameters of the another candidate target cell to be used by the UE when connected to the base station and comprises an execution condition regarding when to perform conditional cell mobility between the UE and the another candidate target cell when connected to the base station,

[0266] • Sending the generated cell configuration for at least another candidate target cell to the source base station.

[0267] exist Fig.17 A corresponding sequence diagram of an exemplary source base station behavior consistent with the source base station and corresponding method discussed above is shown in . The sequence diagram shows an exemplary and simplified implementation of the source base station method presented above.

[0268] Fig.18 A simplified and exemplary target base station structure according to an exemplary embodiment of the improved mobility process is shown, which can be based on a combination of Fig.13 The general base station structure explained above is implemented. Fig.18 The various structural elements of the target base station shown in can be interconnected with each other, for example using corresponding input / output nodes (not shown), for example, to exchange control and user data and other signals. Although not shown for illustrative purposes, the target base station may include further structural elements.

[0269] As is apparent therefrom, the target base station comprises a receiver for receiving a cell configuration parameter request, and a cell configuration generating circuit.

[0270] In the present case, as will become apparent from the following disclosure, the receiver of the target base station may therefore exemplarily be configured to at least partially perform one or more of the following operations: receiving a request for cell configuration parameters from another base station, and receiving cell configuration parameters, etc.

[0271] In the present case, as will become apparent from the following disclosure, the processing circuitry of the target base station may therefore exemplarily be configured to at least partially perform one or more of the following operations: perform a conditional cell mobility procedure, generate a cell configuration, etc.

[0272] In the present case, as will become apparent from the following disclosure, the transmitter of the target base station may therefore exemplarily be configured to at least partially perform one or more of the following operations: transmit the generated cell configuration, etc.

[0273] An exemplary process as will be disclosed in further detail below is implemented by a target base station including the following items. A receiver of the target base station receives a request from a source base station for 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. In response to receiving the request, a circuit of the target base station generates a cell configuration of at least another candidate target cell. The cell configuration of the other candidate target cell includes the cell configuration parameters of the other candidate target cell to be used by the UE when connected to the base station, and includes an execution condition regarding when to perform conditional cell mobility between the UE and the other candidate target cell when connected to the base station. The transmitter of the target base station sends the generated cell configuration for at least another candidate target cell to the source base station.

[0274] The corresponding method comprises the following steps performed by the target base station:

[0275] receiving, from a source base station, a request for requesting a cell configuration parameter 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,

[0276] generating, in response to receiving the request, a cell configuration of at least another candidate target cell, wherein the cell configuration of the another candidate target cell comprises cell configuration parameters of the another candidate target cell to be used by the UE when connected to the base station, and comprises an execution condition regarding when to perform conditional cell mobility between the UE and the another candidate target cell when connected to the base station,

[0277] The generated cell configuration for at least another candidate target cell is sent to the source base station.

[0278] exist Fig.19 A corresponding sequence diagram of an exemplary target base station behavior consistent with the target base station and corresponding method discussed above is shown in The sequence diagram shows an exemplary and simplified implementation of the target base station method presented above.

[0279] As explained above, an improved UE, an improved source base station and an improved target base station participate in an improved mobility procedure in order to achieve this objective, overcome some of the identified problems and achieve advantages.

[0280] The mobility improvement process in which the improvement device presented above participates will be explained below.

[0281] For the purpose of explanation and illustration, first, it is exemplarily assumed that the improved mobility procedure is an improved conditional handover procedure (improved CHO procedure). In general, conditional handover can be understood as a process in which the UE disconnects from the source cell and connects to a candidate target cell (possibly among many candidates) when a condition is met. Conditional handover can be used independently of whether the UE is in dual connectivity; therefore, CHO can be used to change the primary cell of the UE, and can also be used to change the primary cell of the UE in dual connectivity, where the primary cell is part of the primary cell group of the UE.

[0282] However, this assumption of CHO as an improved conditional cell mobility procedure should not be understood as the improved mobility procedure should be limited to conditional handover. Instead, the principles based on the improved mobility procedure are also applicable to other conditional cell mobility procedures, such as the conditional cell change procedure (e.g., see CPC above) and the conditional cell add procedure (e.g., see CPA above). A more detailed explanation of the improved CPC procedure and the improved CPA procedure will be further provided below.

[0283] Fig. 20 is a signaling diagram of an exemplary and simplified implementation of the improved CHO procedure, showing the message exchange between the different participating entities (here UE, gNB0, gNB1 and gNB2) and the steps performed at these entities.

[0284] Assume that the UE is currently connected to the source gNB0. However, according to the improved CHO procedure, the source gNB's preparation for CHO is different from the corresponding CHO preparation in the prior art (see, for example, Fig. 9 and Fig.10 ) is significantly different. In particular, CHO preparation involves preparing 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 connected to the source cell gNB0. In addition, however, according to the improved CHO procedure, the multiple CHO configurations may also include a CHO configuration that the UE does not use now when connected to the source cell gNB0, but that the UE will use in the future when connected to another serving cell (such as gNB1 or gNB2).

[0285] In other words, the multiple CHO configurations include different subsets of CHO configurations, where one subset of the CHO configurations will be used immediately by the UE when connecting to the source cell gNB0. However, at least one other subset of the CHO configurations in the multiple cell configurations is pre-prepared for later use.

[0286] For example, in Fig. 20 In an exemplary scenario, multiple CHO configurations may include the following:

[0287] CHO Configuration# Contents of cell configuration Associated with subset CHO Configuration 1 gNB1 CHO configuration@gNB0 Subset A CHO Configuration 2 gNB2CHO Configuration@gNB0 Subset A CHO Configuration 3 gNB0 CHO configuration@gNB1 Subset B CHO Configuration 4 gNB2 CHO configuration@gNB1 Subset B

[0288] As is evident from the above table, multiple CHO configurations include CHO configurations 1 and 2 (named, for example, "@gNB0") used when the UE is connected to gNB0. Accordingly, considering that the UE is currently connected to source gNB0, the UE will evaluate CHO configurations 1 and 2 for potential CHO.

[0289] In addition, the UE also receives CHO configurations 3 and 4, which are future pre-prepared CHO configurations, i.e., in case the CHO execution from the UE to gNB1 is successful. Accordingly, when connecting to the source cell of gNB0, the UE will not consider CHO configurations 3 and 4.

[0290] The above CHO configurations are logically grouped in different subsets of CHO configurations, where subset A is defined to include gNB0-related CHO configurations (i.e., CHO configurations to be used by the UE when connected to gNB0). Subset B is defined to include gNB1-related CHO configurations (i.e., CHO configurations to be used by the UE when connected to gNB1).

[0291] In the above table, multiple CHO configurations 1 do not include a pre-prepared CHO configuration for the case where the UE performs CHO to another candidate target cell gNB2. Therefore, in that case, gNB2 and the UE may have to perform prior art procedures to prepare a CHO configuration for use by the UE at gNB2 (see, for example, above regarding Figures 8 to 10 of the prior art).

[0292] On the other hand, as another exemplary variation, the CHO preparation performed by the source gNB0 may also involve a CHO configuration for pre-preparing a UE connected to gNB2 for CHO. In the described case, the multiple CHO configurations received by the UE may also include the following CHO configurations 5 and 6.

[0293] CHO Configuration# Contents of cell configuration Association with subsets CHO Configuration 5 gNB0 CHO configuration@gNB2 Subset C CHO Configuration 6 gNB1 CHO configuration@gNB2 Subset C

[0294] CHO configurations 5 and 6 are defined to be associated with subset C, which is a subset that includes all gNB2-related CHO configurations (i.e., the CHO configurations to be used by the UE when connected to gNB2).

[0295] Accordingly, the plurality of CHO configurations 1-6 therefore include a subset of each CHO configuration within a subset. For example, from the perspective of subset A, for CHO configuration 1, the plurality of CHO configurations also include subset B, which relates to a case where the UE performs CHO according to the CHO configuration 1. Similarly, from the perspective of subset A, for CHO configuration 2, the plurality of CHO configurations also include subset C, which relates to a case where the UE performs CHO according to the CHO configuration 2.

[0296] In addition, each of the CHO configurations may include a cell configuration parameter for performing CHO with the corresponding candidate target cell, and may also include an execution condition regarding when to perform the CHO process with the corresponding candidate target cell. Therefore, conceptually, the CHO configurations may have the same (or similar) content, respectively, compared to the CHO configurations used in the prior art.

[0297] The following will specifically combine Fig.21 An exemplary implementation of how the source gNB0 can prepare multiple CHO configurations is explained in detail.

[0298] Therefore, the above-mentioned plurality of CHO configurations 1-6 include more than one CHO configuration for corresponding candidate target cells, in this exemplary scenario, two CHO configurations for each candidate target cell.

[0299] On the other hand, within a subset, the CHO configurations of the subset are respectively related to different candidate target cells. For example, CHO configurations 1 and 2 of subset A involve different candidate target cells gNB1 and gNB2.

[0300] As from Fig. 20 As is further apparent, after preparing the multiple CHO configurations, the source gNB 10 sends them to the UE. The UE will then proceed to process the CHO configurations that the UE will evaluate when connected to its current serving cell (here gNB0). Accordingly, the UE will evaluate the execution conditions of the CHO configurations 1 and 2 associated with gNB0 to determine whether some execution conditions of the CHO configurations are met.

[0301] On the other hand, the UE will not process CHO configurations that do not involve the current serving cell, that is, will not process CHO configurations of other subsets of the multiple CHO configurations, for example, CHO configurations of subsets B and C. Therefore, the UE does not waste resources and time to process CHO configurations for which CHO is not performed.

[0302] When the execution condition of an evaluated CHO configuration is met, the UE continues to perform the CHO procedure with the corresponding candidate target cell of the met CHO configuration. Fig. 20 In the exemplary scenario, it is assumed that the UE performs a CHO procedure with the candidate target gNB1. The CHO procedure may be performed based on the configuration parameters of the corresponding CHO configuration for gNB1.

[0303] Another step of the improved CHO procedure involves maintaining the multiple CHO configurations 1-6 upon successful completion of CHO to gNB1. Therefore, at this point in time, the multiple CHO configurations are not deleted from the UE memory. This is different from the conventional CHO procedure (e.g., Figure 8 , 9In contrast to that explained in UE.10, in the conventional CHO process, the UE releases all CHO configurations upon successful CHO.

[0304] Thus, CHO configurations 3 and 4 are immediately available at the UE to be processed when connecting to the new serving cell gNB 1. Thus, delays for performing subsequent CHO are avoided, which would otherwise be caused by the required preparation of the new CHO configuration at the new serving cell gNB 1.

[0305] CHO configurations 3 and 4 are gNB1-related CHO configurations of subset B. In a manner corresponding to before, the UE may evaluate the execution conditions of gNB1-related CHO configurations 3 and 4 to determine whether some execution conditions are met. Again, the UE will not process CHO configurations that do not involve the current serving cell (here serving cell gNB1).

[0306] As from Fig. 20 Obviously, it is exemplarily assumed that the execution conditions of gNB2 CHO configuration 4 (see the table above) are met, so that the UE performs a CHO process with the candidate target gNB 2. The CHO process can be performed based on the configuration parameters of the corresponding CHO configuration 4 for gNB2.

[0307] Similarly, upon successful completion of CHO to gNB2, the UE again maintains multiple CHO configurations 1-6. Therefore, CHO configurations 5 and 6 are immediately available at the UE to be processed when connecting to the new serving cell gNB2.

[0308] The modified CHO process can then continue in the same manner. Fig. 20 As shown in the figure, the UE can perform another CHO process with gNB0 or ​​gNB1, etc.

[0309] According to an exemplary embodiment, the following ASN1 definition defines signaling that can be used by the source gNB0 to notify the UE of the candidates included in the subset (e.g., gNB1 and gNB2 of subset A).

[0310]

[0311] Accordingly, a candidate target cell may be identified by a physical cell ID and an ARFCN value (see the bold and underlined text above). Thus, to define a subset of two candidate target cells (e.g., subset A), source gNB0 may send the above item twice, including the corresponding physical cell IDs and ARFCNs identifying the two candidate target cells (e.g., for subset A, gNB1 and gNB2).

[0312] In the above explanation of the improved CHO procedure, it is simply assumed that the UE knows which CHO configuration / s to use upon successful completion of the CHO procedure to the new serving cell. The following exemplary embodiments of the improved CHO procedure provide some details on how the UE can determine the appropriate CHO configuration to use. According to a first embodiment, the UE determines the appropriate CHO configuration based on the current serving cell. Therefore, each CHO configuration can be associated with the cell in which it should be used, for example, the above CHO configurations 1 and 2 are associated with the cell of gNB0, the above CHO configurations 3 and 4 are associated with the cell of gNB1, and the above CHO configurations 5 and 6 are associated with the cell of gNB2. Therefore, the UE can determine the CHO configuration associated with the current serving cell when connecting to the new serving cell. According to a similar embodiment, the UE determines the appropriate CHO configuration as a CHO configuration belonging to a subset, which in turn is associated with the current serving cell. This first embodiment has the advantage that no further signaling needs to be exchanged between the base station and the UE to determine the appropriate CHO configuration.

[0313] According to a second embodiment, which CHO configurations the UE is to use may be controlled by the new serving cell. Accordingly, the new serving cell may send an indication to the UE indicating which CHO configurations the UE is to use. For example, the indication may identify several CHO configurations individually (e.g., gNB1 will identify CHO configurations 3 and 4), or may collectively identify a subset of CHO configurations by indicating a subset (e.g., gNB1 will identify subset B). The indication may be sent by the new serving cell to the UE, for example, during a CHO procedure performed by the UE with the new serving cell. The new serving cell may use a suitable RRC message to carry the indication to the UE.

[0314] According to another embodiment of the improved CHO process that can be combined with the above or the following, the CHO configuration can have an activated or deactivated state (alternatively, referred to as active and inactive). Accordingly, a CHO configuration with an activated state is processed by the UE, while a CHO configuration with a deactivated state is not processed by the UE. Accordingly, the improved CHO process according to this embodiment also involves appropriately setting the state of the CHO configuration according to the basic concept explained above. For example, the UE will set the state of each CHO configuration to activated or deactivated depending on whether it is to process the CHO configuration. In the exemplary scenario discussed above, when the UE is connected to gNB0, the state of CHO configurations 1 and 2 is set to the activated state, and the state of CHO configurations 3, 4, 5 and 6 is set to the deactivated state. In addition, when the UE is connected to gNB1, the UE sets the state of CHO configurations 3 and 4 to the activated state, and sets the state of CHO configurations 1, 2, 5 and 6 to the deactivated state. The process of setting the state of the CHO configuration may be performed autonomously by the UE based on the current serving cell (see, eg, the first embodiment above) or based on a suitable indication from the current serving cell (see, eg, the second embodiment above).

[0315] According to another embodiment of the improved CHO process that can be combined with the above or the following, a mechanism for setting the use of the CHO configuration on a cell-specific basis is introduced. Specifically, the UE receives a cell status indication from a current serving base station (e.g., a source base station gNB0), wherein the cell status indication indicates one or more candidate cells for which an associated CHO configuration is to be activated or deactivated.

[0316] Upon receiving a cell status indication, the UE may deactivate or activate the CHO configuration associated with the indicated cell.

[0317] For example, the cell status indication may indicate a deactivated cell, in which case the UE deactivates those CHO configurations associated with that cell. Based on the exemplary CHO configurations 1-6 discussed above, and considering the case when the cell status indication indicates a deactivated cell of gNB2, CHO configurations 2 and 4 are deactivated. Therefore, the UE will only process CHO configuration 3 of gNB0 when connected to gNB1, and similarly, the UE will only process CHO configuration 1 of gNB1 when connected to gNB0. Therefore, the UE will no longer perform CHO to the deactivated cell gNB2.

[0318] For example, the cell-specific mechanism may be useful in an exemplary scenario where a previously available candidate target cell is no longer available as a target for a CHO procedure. In one example, assume 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 UE no longer needs to process any CHO configuration related to the no longer available gNB2.

[0319] To this end, a cell-specific mechanism allows all CHO configurations associated with a cell to be collectively deactivated by providing a cell status indication to the UE.

[0320] Conversely, the cell status indication may also be used to indicate activation of a cell, for example in order to activate all those (deactivated) CHO configurations related to the cell.

[0321] In the above, it is simply assumed that the cell status indication is sent to the UE by the current serving cell of the UE. In addition, several exemplary embodiments provide details on transmitting the cell status indication. According to two exemplary embodiments, the cell status indication is carried by a new information element in an RRC message (such as an RRC reconfiguration message) or by a control element of a MAC message.

[0322] Furthermore, in one exemplary variation, the cell status indication is implemented as a bitmap, wherein each bit of the bitmap is associated with a candidate target cell, and one value of the bit indicates activation of the CHO configuration of the associated candidate target cell, and another value of the bit indicates deactivation of the CHO configuration of the associated candidate target cell.

[0323] The bitmap can for example be constructed as follows:

[0324] C7 C6 C5 C4 C3 C2 C1 C0 C15 C14 C13 C12 C11 C10 C9 C8 C23 C22 C21 C20 C19 C18 C17 C16 C31 C30 C29 C28 C27 C26 C25 C24

[0325] The above bitmap assumes 32 possible candidate target cells C0-C31. A value of 1 may indicate that the associated candidate cell is activated, and a value of 0 may indicate that the associated candidate cell is deactivated.

[0326] In the following, different exemplary embodiments of improving the CHO procedure will be explained, in particular in conjunction with the structure of multiple CHO configurations.Existing (eg Release 16) signaling of CHO configurations only supports up to 8 candidate cells to be processed by the UE.

[0327] According to the first exemplary embodiment, the multiple CHO configurations of the improved CHO procedure are also limited to at most 8 exemplary CHO configurations. This has the advantage of ensuring backward compatibility, since legacy UEs (which do not support the improved CHO configuration) can also handle multiple CHO configurations. Then, within the 8 CHO configurations, different subsets of CHO configurations can be defined to be selectively used by the UE according to the improved CHO procedure (according to any of the embodiments explained above or below). For example, this exemplary embodiment can be applied to CHO configurations 1-6 presented above in order to obtain three separate subsets of CHO configurations.

[0328] For legacy UEs, all CHO configurations (up to 8 CHO configurations) will be processed considering that legacy UEs cannot distinguish different subsets of CHO configurations.

[0329] According to another second exemplary embodiment, according to the improved CHO procedure, there may be more than 8 CHO configurations, so that the improved UE is configured with more than 8 CHO configurations, for example, up to 16, 24 or 32 CHO configurations. However, in an exemplary variant thereof, these CHO configurations may be organized in a sequence, and only the first 8 CHO configurations in the sequence may be used for CHO in the current serving cell. In other words, the preparation of multiple CHO configurations is limited so that only a maximum of 8 CHO configurations may be prepared for a subset. For example, upon successful completion of the CHO procedure between the UE and another target cell, the UE may replace the first 8 elements of the sequence with the 8 CHO configurations applicable to the new serving cell.

[0330] For legacy UEs, all first 8 CHO configurations will be processed correctly. This may be consistent with the existing Release 16 specification, which requires the UE to evaluate all stored CHO configurations for CHO, i.e., no single candidate target cell (and the corresponding stored CHO configuration) can be exempted from being evaluated as a candidate for CHO. The legacy UE does not know the remaining CHO configurations after the first 8 CHO configurations, so the legacy UE will not process the remaining CHO configurations. According to another exemplary implementation of the improved CHO process of the first technical solution, the following may be defined for the new Release 18 according to the 3GPP standard:

[0331]

[0332]

[0333]

[0334]

[0335] As is apparent from the above new exemplary definition of 3GPP Release 18, a new parameter maxNrofCondCell-r18 will be defined that allows a maximum of 32 conditional candidate SpCells.

[0336] Additionally, a new CondReconfigToAddModList will be defined, referencing this new parameter maxNrofCondCells-r18. Additionally, a new CondReconfigID-r18 is defined, allowing identification of CHO configurations.

[0337] Accordingly, when referring to the second embodiment according to which the first 8 CHO configurations are to be considered as candidates for the current serving cell, the sequence of CHO configurations may be given by the above-mentioned new 3GPP Rel.18 definition, in particular the sequence provided by CondReconfigID-r18.

[0338] In the above definitions, it is assumed that the new functionality is introduced for 3GPP Release 18, and thus the term "r18" is included. However, it should also be noted that the new functionality may be introduced in later 3GPP releases (e.g., 19, 20, etc.), in which case the above definitions may be renamed by using the corresponding terms "r19", "r20", etc. instead of "r18".

[0339] In the above, different embodiments of improving the CHO procedure have been presented. In different embodiments, the preparation of multiple CHO configurations and the transmission of these multiple CHO configurations to the UE have been discussed. In the following, detailed and exemplary embodiments of improving the CHO procedure will be presented, in particular with regard to Fig. 20 How to prepare multiple CHO configurations for the source gNB. This will be based on Fig.21 to complete, which shows exemplary and simplified signaling exchanges between different entities involved in the preparation of multiple CHO configurations according to the improved CHO procedure.

[0340] For the sake of clarity and understanding, Fig.21 The signaling diagram shows specific signal sequences in a grouped manner. In particular, the pre-preparation of the gNB1-related CHO configuration performed by gNB1 follows the logical order of request and response, but is shown together in sequence only for the sake of clarity. Similarly, the pre-preparation of the gNB2-related CHO configuration performed by gNB2 follows the logical order of request and response, but is shown together in sequence only for the sake of clarity. Similarly, the preparation of the gNB0-related CHO configuration performed by gNB0 follows the logical order of request and response, but is also shown together for the sake of clarity. However, Fig.21 The sequence of messages may be different, yet still follow the logical order of steps.

[0341] It is assumed that gNB0, to which the UE is initially connected, is responsible for preparing multiple CHO configurations. Accordingly, the preparation involves preparing gNB1 and gNB2 CHO configurations to be used when the UE is connected at gNB0. To this end, gNB0 sends a CHO Preparation message to gNB1 and receives a CHO ACK message from gNB1 with the requested CHO configuration parameters of gNB1 for potential CHO from gNB0. Similarly, gNB0 sends a CHO Preparation message to gNB2 and receives a CHO ACK message from gNB2 with the requested CHO configuration parameters of gNB2 for potential CHO from gNB0.

[0342] Although not in Fig.21 , but gNB0 may then generate a gNB0-related CHO configuration for gNB1 by determining appropriate execution conditions and including corresponding CHO configuration parameters for gNB1 received from gNB1. In a corresponding manner, gNB0 may then generate a gNB0-related CHO configuration for gNB2 by determining appropriate execution conditions and including corresponding CHO configuration parameters for gNB2 received from gNB2.

[0343] Therefore, gNB0 has prepared the CHO configuration for subset A, which is the CHO configuration to be processed when the UE connects to gNB0.

[0344] Furthermore, CHO preparation also involves pre-preparation for CHO in the future, where the UE is connected to one of gNB1 or gNB2. CHO pre-preparation is performed by gNB1 and gNB2, respectively, and can be triggered by a CHO preparation message sent from gNB0, respectively, as explained above for Subset A CHO preparation.

[0345] For example, after gNB1 receives the CHO preparation message from gNB0, gNB1 sends a CHO pre-preparation message to gNB2 and gNB0 to request CHO configuration parameters for the corresponding CHO from gNB1 to gNB2 and gNB0, respectively. In response, gNB1 receives the requested CHO configuration parameters from gNB2 and gNB0, such as Fig.21 shown.

[0346] Although not in Fig.21 , but gNB1 may then generate a gNB1-related CHO configuration for gNB2 by determining appropriate execution conditions and including corresponding CHO configuration parameters for gNB2 received from gNB2. In a corresponding manner, gNB1 may generate a gNB1-related CHO configuration for gNB0 by determining appropriate execution conditions and including corresponding CHO configuration parameters for gNB0 received from gNB0.

[0347] The gNB1-related CHO configuration for gNB2 and gNB0 generated thereby is then sent by gNB1 to gNB0 (gNB0 has triggered pre-preparation). As a result, gNB0 has thus obtained the CHO configuration for subset B, i.e. the CHO configuration that the UE is to process when connecting to gNB1.

[0348] As just explained for the pre-preparation performed by gNB1, gNB2 may also perform corresponding pre-preparation. For example, after gNB2 receives the CHO preparation message from gNB0, gNB2 sends a CHO pre-preparation message to gNB0 and gNB1 to request CHO configuration parameters for the corresponding CHO from gNB2 to gNB0 and gNB1, respectively. In response, gNB2 receives the requested CHO configuration parameters from gNB0 and gNB1, such as Fig.21 shown.

[0349] Although not in Fig.21 , but gNB2 may then generate a gNB2-related CHO configuration for gNB0 by determining appropriate execution conditions and including corresponding CHO configuration parameters for gNB0 received from gNB0. In a corresponding manner, gNB2 may generate a gNB2-related CHO configuration for gNB1 by determining appropriate execution conditions and including corresponding CHO configuration parameters for gNB1 received from gNB2.

[0350] The gNB2-related CHO configuration for gNB0 and gNB1 generated thereby is then sent by gNB2 to gNB0 (gNB0 having triggered pre-preparation). Thus, gNB0 has thereby obtained the CHO configuration for subset C, i.e. the CHO configuration to be processed when the UE is connected to gNB1.

[0351] Then, when the UE is located in different cells of gNB0, gNB1 and gNB2, various CHO configurations can be sent to the UE for different CHO.

[0352] In the above exemplary embodiments, as shown in FIG. Fig.21 As described, it is assumed that the gNB1-related CHO configurations for gNB0 and gNB2 are transmitted separately from each other and also separately from the gNB0-related CHO configuration for gNB1. However, according to an exemplary variation of this embodiment, one CHO ACK message may carry more than one CHO configuration, such as one or more of the gNB1-related CHO configurations for gNB0 and gNB2 and the gNB0-related CHO configuration for gNB1.

[0353] Similarly, assuming the improved CHO ACK message, gNB2 may send one or more of the gNB2-related CHO configurations for gNB0 and gNB1 and the gNB0-related CHO configurations for gNB2 back to gNB0 in one CHO ACK message.

[0354] To this end, a new parameter (eg, an octet string or container) for the conditional configuration may be included in the handover confirmation message from the target node to the source node.

[0355] According to an exemplary 5G-compatible implementation, as known for example from TS 38.413 v17.0.0, the handover request confirm message may apply as follows:

[0356] 9.2.3.5 Handover Request Confirmation (according to TS 38.413 v17.0.0)

[0357] This message is sent by the target NG-RAN node to inform the AMF about the resources prepared at the target.

[0358] Direction: NG-RAN node → AMF.

[0359]

[0360]

[0361] In the above definitions, additional proposed definitions for conditional configuration containers are bold and underlined.

[0362] Accordingly, according to this variant, the candidate target cell (whether gNB1 or gNB2) does not immediately respond to the CHO preparation message received from gNB0. Instead, the candidate target cell can wait for the corresponding CHO pre-preparation process to end in order to then send all the generated information back to the requesting gNB0 together.

[0363] The above-mentioned implementation of the improved CHO process is irrelevant to whether the UE is in dual connectivity. In the following, it is exemplarily assumed that the UE is in dual connectivity.

[0364] According to an exemplary embodiment, the UE is configured with a primary cell group MCG and multiple secondary cell groups SCG, i.e., with more than one SCG. For example, in a 5G-compatible exemplary embodiment, the UE may be configured with more than one MRDC-SecondaryCellGroupConfig information element as part of the RRCReconfiguration message (see, e.g., TS 38.331v17.1.0).

[0365] However, for a UE at a given time, only one SCG among the multiple SCGs is active, so that the UE is connected to one or more cells of the active SCG. The other SCGs are inactive (also referred to as "deactivated").

[0366] This embodiment is different from the current 3GPP specifications, such as TS 38.331, according to which a UE can be configured with only one SCG. In general, the 3GPP specifications allow a UE to be configured with two cell group configuration sets, for example, one set for the primary cell group MCG and the other set for the secondary cell group SCG. In addition, one SCG can be configured to be activated or deactivated, while the MCG always remains in the activated state. The deactivation can be carried via an RRC message. Conditional PSCell Change (CPC) can occur as an intra-SN handover or an inter-SN handover.

[0367] According to the embodiment, there are at least two different possibilities as to how the UE determines which SCG among multiple SCGs is the active SCG. According to a first option, the UE may determine the active SCG as the SCG that is first configured for the UE. For example, the UE may be continuously configured with SCGs, and even when additional SCGs are subsequently configured, the first added SCG (when the UE does not yet have an SCG) may be determined as the active SCG. According to a partial option that may be in addition to or in lieu of the first option, the UE determines the active SCG based on an explicit indication received, for example, from a gNB. This explicit indication may then also be used to change the active SCG from one SCG to another.

[0368] Configuration of several SCGs may be useful in order to save signaling overhead. For example, assume that the UE has two SCGs, a first active SCG and a second inactive SCG, and the UE wants to perform a CPC procedure with a target cell (PSCell) that is not in the list of SCells configured for the currently active first SCG. However, the target cell is in the list of SCells configured for the currently inactive second SCG. Therefore, the CPC procedure results in the activation of the second SCG, for which the SCG configuration information is already available at the UE. Therefore, the UE does not need to perform a reconfiguration procedure for setting up a new second SCG. Furthermore, the first SCG can be maintained at the UE and deactivated, so that the UE does not need to release the configuration of the first SCG.

[0369] According to the current 3GPP standard (eg, TS 38.331), there is an existing IE scg-State for indicating whether the SCG is in a deactivated state. According to a variation of this embodiment, this IE (or another IE similar to the above SCG state) may be reused for dual connectivity and multiple SCG situations.

[0370] The following exemplary details are provided for defining how different SCGs may be configured to a UE. In one example, the UE receives configuration information, for example in an RRC message, from its current serving cell. New variables may be introduced in the RRC to store the configuration of additional SCGs.

[0371] The configuration information may include, for example, one or more of the following:

[0372] - the common cell IDs of the cells of the corresponding cell group,

[0373] - a common frequency range of the cells of the corresponding cell group, and

[0374] - Common radio resources of the cells of the corresponding cell group.

[0375] In another additional example, the configuration information of the SCG may also include a list of candidate cells for evaluating the CHO / CPC / CPA process when the SCG is activated.

[0376] According to another variant, the UE does not perform one or more of the following procedures for the deactivated SCG:

[0377] - Random access to the cell of the corresponding SCG,

[0378] - Radio link measurements with the cells of the corresponding SCG, and

[0379] -Uplink synchronization with the cell of the corresponding SCG.

[0380] In particular, according to the current 3GPP specification, when a SCG is configured for a UE, the UE is expected to immediately apply the configuration and then perform random access on the PSCell of the SCG, including achieving uplink synchronization. In addition, regardless of the SCG state (e.g., activated or deactivated), the UE is expected to perform RLM measurements on one SCG.

[0381] However, such behavior is disadvantageous in the case where more than one SCG is configured for the UE. One function of having multiple SCG configurations at the UE is to enable the UE to apply conditional configurations immediately after a successful handover. Therefore, as described above, the UE does not need to perform these procedures for additional SCGs that are in an inactive state.

[0382] Instead, the UE simply saves the configurations of these additional, deactivated SCGs for future use and does not apply them currently. The configurations of these additional, deactivated SCGs are applied when needed.

[0383] By introducing several SCG configurations, it is beneficial to also introduce a mechanism to distinguish different SCG configurations at the UE. This helps to address individual SCG configurations, for example, to support the addition, modification, release and / or activation (deactivation) of SCG configurations.

[0384] To this end, an exemplary option allows the SCG configuration to be identified based on a combination of the cell ID of the PSCell in the corresponding SCG and an identifier of the radio resources used for transmission and reception by the cells of the corresponding SCG. In one example, the radio resource identifier is the ARFCN (Absolute Radio Frequency Channel Number). Therefore, this option reuses the ID parameters of the SCG configuration to allow identification and differentiation between them. However, a disadvantage may occur if two SCG configurations are configured with the same PSCell and the same radio resource identifier, but are different, for example, in having different SCells or including other configuration elements (for example, in the SN intra-configuration). The two configurations cannot therefore be distinguished. In addition, this first option may result in higher signaling overhead, since the combination of the two IDs is quite long and may have to be signaled each time the SCG configuration is addressed, for example for modification, release or (de)activation.

[0385] According to the second option, a new dedicated SCG identifier may be created to distinguish multiple SCGs. In this case, the length of the dedicated SCG identifier only needs to be as long as required to distinguish the maximum number of SCGs, for example, 5 bits to distinguish 32 SCGs. The new SCG identifier may be named, for example, scgConfigIdentifier.

[0386] According to another exemplary embodiment, when the UE is configured to perform CPC or CPA, the configuration may include a configuration for the SCG that can be applied once the UE determines a suitable candidate cell for handover. The configuration also includes associated execution conditions for identifying whether the candidate is suitable for conditional handover. Once the candidate becomes suitable or is triggered, the UE applies the associated configuration for the SCG and performs handover. Taking into account the presence of several SCG configurations, the UE determines which of the several SCG configurations should be used when performing a handover to a configured candidate cell.

[0387] According to one option, the UE stores information associating each of the plurality of SCGs with a cell. Then, upon successful completion of a conditional procedure to a candidate target cell, the UE determines the SCG associated with the candidate target cell of the completed conditional procedure based on the stored information.

[0388] This allows the UE to identify its SCG configuration which has to be applied.

[0389] Improved CPC process

[0390] After the above detailed explanation of the improved CHO procedure, an exemplary and simplified implementation of the improved conditional cell change (CPC) procedure will be explained below. The improved CPC procedure may be based on the principles explained above in conjunction with the improved CHO procedure, so most of them will not be repeated.

[0391] The improved CPC procedure can be understood as a procedure according to which the UE disconnects from the source cell and connects to a candidate target cell (possibly among many candidates) when the execution conditions are met, i.e., corresponds to the CHO procedure discussed above. The CPC procedure is typically used when the UE is in dual connectivity, for example, when the UE has been configured with a primary cell group and a secondary cell group and is connected to at least one primary cell (PCell) of the primary cell group and at least one primary cell (PSCell) of the secondary cell group. The improved CPC procedure can be performed by the UE in order to change the PSCell of the SCG. Accordingly, the source cell and target cell participating in the CPC belong to the secondary cell group of the UE in the dual connectivity.

[0392] Fig. 22 This exemplary and simplified implementation of the improved Conditional Cell Change (CPC) procedure is shown, illustrating the message exchange between the different participating entities (here UE, gNB0, gNB1 and gNB2) and the steps performed at these entities.

[0393] As from Fig. 22 It is obvious that the CPC preparation differs significantly from the corresponding CPC preparations in the prior art, see for example Fig.11 . In particular, CPC preparation involves preparing multiple CPC configurations for possible candidate target cells gNB1 and gNB2. Therefore, the multiple CPC configurations may include CPC configurations to be used by the UE when connected to the source cell gNB0. In addition, however, according to the improved CPC procedure, the multiple CPC configurations may also include CPC configurations that the UE does not use now when connected to the source cell gNB0, but that the UE is to use in the future when connected to another serving cell (such as gNB1 or gNB2).

[0394] In other words, the multiple CPC configurations include different subsets of CPC configurations, where one subset of CPC configurations will be used immediately by the UE connected to the source cell gNB0. However, at least one additional subset of CPC configurations in the multiple cell configurations is prepared for later use.

[0395] Similar to that explained in detail in conjunction with the improved CHO process, multiple CPC configurations may include:

[0396] CPC Configuration# Contents of cell configuration Associated with subset CPC Configuration 1 gNB1 CPC configuration@gNB0 Subset A CPC Configuration 2 gNB2 CPC configuration@gNB0 Subset A CPC Configuration 3 gNB0 CPC configuration@gNB1 Subset B CPC Configuration 4 gNB2 CPC configuration@gNB1 Subset B

[0397] According to an exemplary option, the plurality of CPC configurations may also include:

[0398] CPC Configuration# Contents of cell configuration Associated with subset CPC Configuration 5 gNB0 CPC Configuration@gNB2 Subset C CPC Configuration 6 gNB1 CPC configuration@gNB2 Subset C

[0399] As from Fig. 22 As is further apparent, after preparing the multiple CPC configurations, the source gNB0 sends them to the UE. The UE will then proceed to process the CPC configurations to be evaluated when the UE is connected to its current serving cell (here gNB0). Accordingly, the UE will evaluate the execution conditions of CPC configurations 1 and 2 associated with gNB0 to determine whether some execution conditions of the CPC configurations are met.

[0400] On the other hand, the UE will not process CPC configurations that do not involve the current serving cell, that is, will not process CPC configurations of other subsets of the multiple CPC configurations, for example, CPC configurations of subsets B and C. Therefore, the UE does not consume resources and time to process CPC configurations for which CPC is not performed.

[0401] When the execution condition of an evaluated CPC configuration is met, the UE continues to perform the CPC procedure with the corresponding candidate target cell of the met CPC configuration. Fig. 22 In the exemplary scenario, it is assumed that the UE performs a CPC procedure with the candidate target gNB1. The CPC procedure may be performed based on the configuration parameters of the corresponding CPC configuration for gNB1.

[0402] Another step in improving the CPC procedure involves maintaining the multiple CPC configurations 1-6 upon successful completion of CPC to gNB1. Thus, the multiple CPC configurations are not deleted from the UE memory at this point in time. This is different from the conventional CPC procedure (e.g. Fig.11 In contrast, in the traditional CPC process, the UE releases all CPC configurations when CPC is successful.

[0403] CPC configurations 3 and 4 are therefore immediately available at the UE for processing upon connection to the new serving cell gNB 1. Thus, delays for performing subsequent CPC are avoided, which would otherwise be caused by the required preparation of the new CPC configuration at the new serving cell gNB 1.

[0404] CPC configurations 3 and 4 are gNB1-related CPC configurations for subset B. In a manner corresponding to before, the UE may evaluate the execution conditions of gNB1-related CPC configurations 3 and 4 to determine whether some execution conditions are met. Again, the UE will not process CPC configurations that do not involve the current serving cell (here, the new serving cell gNB1).

[0405] As from Fig. 22Obviously, it is assumed that the execution conditions of gNB2 CPC configuration 4 (see the table above) are met, so that the UE performs the CPC process with the candidate target gNB2. The CPC process can be performed based on the configuration parameters of the corresponding CPC configuration 4 for gNB2.

[0406] Similarly, upon successful completion of CPC to gNB2, the UE again maintains multiple CPC configurations 1-6. Thus, CPC configurations 5 and 6 are immediately available at the UE for processing when connecting to the new serving cell gNB2.

[0407] The improved CPC process can then continue in the same manner.

[0408] Further improvements and variations of the Improved CPC process follow the same principles as the corresponding improvements and variations of the Improved CHO process described above. Therefore, details on the Improved CHO process are provided above and will not be repeated.

[0409] For example, in the same manner as explained for the improved CHO procedure, the CPC procedure may be improved with respect to how the UE may determine a suitable CPC configuration to use, e.g. following the first implementation (based on the current serving cell) or based on the second implementation (controlled by the new serving cell by sending an indication to the UE).

[0410] In addition, in the same manner as explained for the improved CHO process, the CPC configuration can have an activated or deactivated state. Accordingly, a CPC configuration with an activated state is processed by the UE, while a CPC configuration with a deactivated state is not processed by the UE. The CPC process can be further improved by allowing the state of the CPC configuration to be set according to the above concepts. The process of setting the state of the CPC configuration can be performed autonomously by the UE based on the current serving cell (see, for example, the first embodiment above) or based on a suitable indication from the current serving cell (see, for example, the second embodiment above). Further details on the improved CHO process are provided above and will not be repeated.

[0411] In addition, in the same manner as explained for the improved CHO process, the CPC process can be further improved by implementing a mechanism for setting the use of the CPC configuration on a cell-specific basis. In particular, the UE receives a cell status indication from a current serving base station (e.g., the source base station gNB0), wherein the cell status indication indicates one or more candidate cells for which the associated CPC configuration is to be activated or deactivated. Upon receiving the cell status indication, the UE can deactivate or activate the CPC configuration associated with the indicated cell. In addition, reference is made to the improved CHO process explained above, and in particular to the details on how to implement the cell status indication, which also applies to the cell status indication of the improved CPC process, in particular including the use of new IEs of RRC messages or CEs of MAC messages, and the use of bitmaps. Further details on the improved CHO process are provided above and will not be repeated.

[0412] Furthermore, in the same manner as explained for the Improved CHO procedure, the CPC procedure may be further improved by allowing multiple CPC configurations to be limited to at most 8. Alternatively, there may be more than 8 CPC configurations, in which case only the first 8 CPC configurations in the sequence may be used for CPC in the current serving cell. Further details on the Improved CHO procedure are provided above and will not be repeated.

[0413] Furthermore, in the same manner as explained for the Improved CHO procedure, the CPC procedure may also involve corresponding exchanges of preparation messages and pre-preparation messages between the various gNBs for preparing multiple CPC configurations. Fig.21 The details are explained in conjunction with the CHO process and these details can also be conceptually applied to the improved CPC process. Fig.21 Details of the improved CHO process are provided and will not be repeated here. However, in short, the improved CPC process may accordingly include preparing a CPC configuration related to gNB0 by the current serving cell of gNB0 based on CPC configuration parameters obtained from gNB1 and gNB2, respectively, and based on execution conditions determined by gNB0.

[0414] In addition, the improved CPC procedure may also include pre-preparing at gNB1 a gNB1-related CPC configuration for gNB2 and gNB0, for example, triggered by a CPC preparation message from gNB0. In addition, the improved CPC procedure may also include pre-preparing at gNB2 a gNB2-related CPC configuration for gNB1 and gNB0, for example, triggered by a CPC preparation message from gNB0. Then, the gNB1-related CPC configuration for gNB2 and gNB0 generated thereby and the gNB2-related CPC configuration for gNB0 and gNB1 generated thereby are sent to gNB0 by gNB1 and gNB2, respectively. Therefore, gNB0 has thereby obtained the CPC configuration for subsets B and C.

[0415] Then, when the UE is located in different cells of gNB0, gNB1 and gNB2, various CPC configurations can be sent to the UE for different CPCs, as shown in reference Fig. 22 Explained.

[0416] In addition, in the same manner as explained for the improved CHO process, the CPC process can also benefit from the configuration of multiple SCGs. Details on how to configure and activate (disable) different SCGs have been provided above for the improved CHO process, and these details also apply to the improved CPC process, so they will not be repeated here. Similarly, details on how the UE determines which SCG among multiple SCGs is the active SCG have been provided above for the improved CHO process, and these details also apply to the improved CPC process, so they will not be repeated here. In addition, details on the UE not needing to perform specific procedures (e.g., random access) for the deactivated SCG have been provided above for the improved CHO process, and these details also apply to the improved CPC process, so they will not be repeated here. How to distinguish between multiple SCGs (see the combination of PSCell ID+ARFCN or a new dedicated SCG ID) is also explained in detail above for the improved CHO process, and it also applies to the improved CPC process, so it will not be repeated here. In addition, details regarding associating the SCG with a candidate cell for activating the SCG once the UE performs a handover to the candidate cell are provided above for the improved CHO procedure and are also applicable to the improved CPC procedure, so they will not be repeated here.

[0417] According to another exemplary embodiment, the subset concept introduced for the improved CPC process can be considered together with the SCG concept of dual connectivity. Both the subset function and the SCG function are grouping concepts for grouping different cells. In one example, a subset can be equivalent to a potential SCG of a UE.

[0418] Furthermore, considering the possibility of having multiple SCGs, multiple subsets can also be considered as multiple SCGs.

[0419] For example, when referring to Fig. 22 When , subset B consists of CPC configurations for gNB0 and gNB2. The potential SCG of the UE when connected to gNB1 can include the same cells, i.e. gNB0 and gNB2.

[0420] Improved CPA Process

[0421] After the above detailed explanation of the improved CHO and CPC procedures, an exemplary and simplified implementation of the improved conditional cell addition (CPA) procedure will be explained below. The improved CPA procedure can be based on the principles explained above in conjunction with the improved CHO procedure, so most of them will not be repeated.

[0422] The improved CPA procedure can be understood as a procedure according to which the UE is connected to a candidate target cell (possibly among many candidates) when the execution condition is met, wherein the candidate target cell then becomes the primary cell of the UE's secondary cell group that is different from the UE's primary cell group. The CPC procedure is typically used when the UE enters dual connectivity, for example, in the process of establishing a secondary cell group and connecting to the primary cell (PSCell) of the secondary cell group. CPA can then also be used to add an additional SCell to the SCG, or to create another SCG with another PSCell, even if the other SCG may be inactive at the beginning.

[0423] Furthermore, CPA does not result in a change in the UE's connection to the primary node (here gNB0), while the UE's connection to the secondary node (SN) can be connected and disconnected based on each CPA. Accordingly, for the following explanation, it is exemplarily assumed that gNB0 is the primary node, and gNB1 and gNB2 are potential secondary nodes to be added via the improved CPA process.

[0424] Fig.23 This exemplary and simplified implementation of the improved Conditional Cell Addition (CPA) procedure is shown, illustrating the message exchange between the different participating entities (here UE, gNB0, gNB1 and gNB2) and the steps performed at these entities.

[0425] As from Fig.23 It is obvious that the CPA preparation differs significantly from the corresponding CPA preparation in the prior art, see for example Fig.12. In particular, CPA preparation involves preparing multiple CPA configurations for possible candidate target cells gNB1 and gNB2. Therefore, the multiple CPA configurations may include a CPA configuration to be used by the UE when connected to the source cell gNB0. In addition, however, according to the improved CPA procedure, the multiple CPA configurations may also include a CPA configuration that the UE does not use now when connected to the source cell gNB0, but the UE is to use in the future when it is additionally connected to another serving cell (such as gNB1 or gNB2).

[0426] In other words, the multiple CPA configurations include different subsets of CPA configurations, where one subset of the CPA configurations will be used immediately by the UE connected to the source cell gNB0. However, at least one other subset of the CPA configurations in the multiple cell configurations is prepared for later use.

[0427] Similar to that explained in detail in conjunction with the improved CHO process, multiple CPA configurations may include:

[0428] CPA Configuration# Contents of cell configuration Associated with subset CPA Configuration 1 gNB1 CPA configuration@gNB0 Subset A CPA Configuration 2 gNB2 CPA Configuration@gNB0 Subset A CPA Configuration 3 gNB0 CPA configuration@gNB1 Subset B CPA Configuration 4 gNB2 CPA configuration@gNB1 Subset B

[0429] According to an exemplary option, the plurality of CPA configurations may further include:

[0430] CPA Configuration# Contents of cell configuration Associated with subset CPA Configuration 5 gNB0 CPA configuration@gNB2 Subset C CPA Configuration 6 gNB1 CPA configuration@gNB2 Subset C

[0431] As from Fig.23 As is further apparent, after preparing multiple CPA configurations, the source gNB sends them to the UE. The UE will then proceed to process the CPA configurations that the UE will evaluate when connected to its current serving cell (here gNB0). Accordingly, the UE will evaluate the execution conditions of CPA configurations 1 and 2 associated with gNB0 to determine whether some execution conditions of the CPA configurations are met.

[0432] On the other hand, the UE will not process CPA configurations that do not involve the current serving cell, that is, it will not process CPA configurations of other subsets in the multiple CPA configurations, for example, CPA configurations of subsets B and C. Therefore, the UE does not consume resources and time to process CPA configurations for which CPA is not performed.

[0433] When the execution condition of an evaluated CPA configuration is met, the UE continues to perform the CPA process with the corresponding candidate target cell of the met CPA configuration. Fig.23 In the exemplary scenario, it is assumed that the UE performs a CPA procedure with a candidate target gNB1, thereby generating a new SCG with the target gNB1 as a PSCell. The CPA procedure may be performed based on the configuration parameters of the corresponding CPA configuration for gNB1.

[0434] Another step in improving the CPA procedure involves maintaining the multiple CPA configurations 1-6 upon successful completion of CPA to gNB1. Thus, the multiple CPA configurations are not deleted from the UE memory at this point in time. This is different from the conventional CPA procedure (e.g., Fig.12 In contrast, in the conventional CPA process, the UE releases all CPA configurations upon successful CPA.

[0435] Thus, CPA configurations 3 and 4 are immediately available at the UE for processing upon connection to the new serving cell gNB 1. Thus, delays for performing subsequent CPAs are avoided, which would otherwise be caused by the required preparation of the new CPA configuration at the new serving cell gNB 1.

[0436] CPA configurations 3 and 4 are gNB1-related CPA configurations of subset B. In a manner corresponding to before, the UE may evaluate the execution conditions of gNB1-related CPA configurations 3 and 4 to determine whether some execution conditions are met. Again, the UE will not process CPA configurations that do not involve the current serving cell (here, the new serving cell gNB1).

[0437] As from Fig.23 Obviously, it is assumed that the execution conditions of gNB2 CPA configuration 4 (see the table above) are met, so that the UE performs another CPA process with the candidate target gNB2 to create another SCG with gNB2 as PSCell. The CPA process can be performed based on the configuration parameters of the corresponding CPA configuration 4 for gNB2.

[0438] Similarly, upon successful completion of CPA with gNB2, the UE again maintains multiple CPA configurations 1-6. Therefore, CPA configurations 5 and 6 are immediately available at the UE for processing when connecting to the new serving cell gNB2.

[0439] The improved CPA process can then continue in the same manner.

[0440] Further improvements and variations of the Improved CPA process follow the same principles as the corresponding improvements and variations of the Improved CHO process described above. Therefore, details on the Improved CHO process are provided above and will not be repeated.

[0441] For example, in the same manner as explained for the improved CHO procedure, the CPA procedure may be improved with respect to how the UE may determine a suitable CPA configuration to use, e.g. following the first implementation (based on the current serving cell) or based on the second implementation (controlled by the new serving cell by sending an indication to the UE).

[0442] Furthermore, in the same manner as explained for the improved CHO procedure, the CPA configuration may have an activated or deactivated state. Accordingly, a CPA configuration with an activated state is processed by the UE, while a CPA configuration with a deactivated state is not processed by the UE. The CPA procedure may be further improved by allowing the state of the CPA configuration to be set according to the above concepts. The process of setting the state of the CPA configuration may be performed autonomously by the UE based on the current serving cell (see, e.g., the first embodiment above) or based on a suitable indication from the current serving cell (see, e.g., the second embodiment above). Further details on the improved CHO procedure are provided above and will not be repeated.

[0443] In addition, in the same manner as explained for the improved CHO process, the CPA process can be further improved by implementing a mechanism for setting the use of the CPA configuration on a cell-specific basis. In particular, the UE receives a cell status indication from a current serving base station (e.g., a source base station gNB0), wherein the cell status indication indicates one or more candidate cells for which an associated CPA configuration is to be activated or deactivated. Upon receiving the cell status indication, the UE can deactivate or activate the CPA configuration associated with the indicated cell. In addition, reference is made to the improved CHO process explained above, and in particular to the details on how to implement the cell status indication, which also applies to the cell status indication of the improved CPA process, in particular including the use of new IEs of RRC messages or CEs of MAC messages, and the use of bitmaps. Further details on the improved CHO process are provided above and will not be repeated.

[0444] Furthermore, in the same manner as explained for the improved CHO procedure, the CPA procedure may be further improved by allowing the number of CPA configurations to be limited to at most 8. Alternatively, there may be more than 8 CPA configurations, in which case only the first 8 CPA configurations in the sequence may be used for CPA in the current serving cell. Further details on the improved CHO procedure are provided above and will not be repeated.

[0445] Furthermore, in the same manner as explained for the Improved CHO procedure, the CPA procedure may also involve corresponding exchanges of preparation messages and pre-preparation messages between the various gNBs for preparing multiple CPA configurations. Fig.21 The details are explained in conjunction with the CHO process and can also be conceptually applied to the improved CPA process. Fig.21 Details of the improved CHO process are provided and will not be repeated here. However, in short, the improved CPA process may accordingly include preparing a gNB0-related CPA configuration by the current serving cell of gNB0 based on CPA configuration parameters obtained from gNB1 and gNB2, respectively, and based on execution conditions determined by gNB0.

[0446] In addition, the improved CPA process may also include pre-preparing at gNB1 a gNB1-related CPA configuration for gNB2 and gNB0, for example, triggered by a CPA preparation message from gNB0. In addition, the improved CPA process may also include pre-preparing at gNB2 a gNB2-related CPA configuration for gNB1 and gNB0, for example, triggered by a CPA preparation message from gNB0. Then, the gNB1-phase CPA configuration for gNB2 and gNB0 generated thereby and the gNB2-related CPA configuration for gNB0 and gNB1 generated thereby are sent by gNB1 to gNB0, respectively. Therefore, gNB0 has thereby obtained the CPA configuration for subsets B and C.

[0447] Then, when the UE is located in different cells of gNB0, gNB1 and gNB2, various CPA configurations can be sent to the UE for different CPA, as shown in reference Fig.23 Explained.

[0448] In addition, in the same manner as explained for the improved CHO process, the CPA process can also benefit from the configuration of multiple SCGs. Details on how to configure and activate (disable) different SCGs have been provided above for the improved CHO process, and these details also apply to the improved CPA process, so they will not be repeated here. Similarly, details on how the UE determines which SCG among multiple SCGs is the active SCG have been provided above for the improved CHO process, and these details also apply to the improved CPA process, so they will not be repeated here. In addition, details on how the UE does not need to perform specific procedures (e.g., random access) for the deactivated SCG have been provided above for the improved CHO process, and these details also apply to the improved CPA process, so they will not be repeated here. How to distinguish between multiple SCGs (see the combination of PSCell ID+ARFCN or a new dedicated SCG ID) is also explained in detail above for the improved CHO process, and it also applies to the improved CPA process, so it will not be repeated here. In addition, details of associating the SCG with a candidate cell for activating the SCG once the UE performs a handover to the candidate cell are provided above for the improved CHO procedure and are also applicable to the improved CPA procedure, so they will not be repeated here.

[0449] Second technical solution

[0450] Fig.24 A simplified and exemplary UE structure of an exemplary implementation of an improved mobility process according to the second technical solution is shown, which can be based on the combination of Fig.13 The general UE structure explained is implemented. Fig.24The various structural elements of the UE shown in the figure may be interconnected with each other, for example using corresponding input / output nodes (not shown), for example, to exchange control and user data and other signals. Although not shown for illustrative purposes, the UE may include further structural elements.

[0451] As from Fig.24 Obviously, the UE may include a cell configuration receiver (used to receive 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.

[0452] In the present case, the receiver of the UE may therefore exemplarily be configured to at least partially perform one or more of reception cell configuration and the like.

[0453] In the present case, as will become apparent from the following disclosure, the processing circuitry of the UE may therefore be exemplarily configured to at least partially perform one or more of the following operations: executing a conditional cell mobility procedure when an execution condition is met, evaluating an execution condition, storing a cell preconfiguration, releasing a previous cell configuration, etc.

[0454] In the present case, as will become apparent from the following disclosure, the transmitter of the UE may thus exemplarily be configured to at least partially perform one or more of sending a measurement report to a serving cell of the UE, etc.

[0455] An exemplary process as will be disclosed in more detail further below is implemented by a UE comprising the following items. 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 with a corresponding candidate target cell, and includes an execution condition regarding when to perform the conditional cell mobility procedure with the corresponding candidate target cell. At least one cell configuration for the corresponding candidate target cell includes a cell pre-configuration for another candidate target cell different from the corresponding candidate target cell, wherein the cell pre-configuration includes cell configuration parameters for the UE to perform the conditional cell mobility procedure to the other candidate target cell when connected to the corresponding candidate target cell. Circuitry of the UE evaluates the execution conditions of the first set of cell configurations. When the execution condition of the corresponding candidate target cell in the first set of cell configurations is met, the circuitry performs the conditional cell mobility procedure with the corresponding candidate target cell based on the cell configuration parameters of the corresponding candidate target cell. Upon successful completion of the conditional cell mobility procedure, the circuitry:

[0456] storing the cell pre-configuration for another candidate target cell as the cell configuration for another candidate target cell,

[0457] · releasing the first set of stored cell configurations, and

[0458] · Evaluate the execution condition of the newly stored cell configuration for another candidate target cell. The corresponding exemplary method comprises the following steps performed by the UE:

[0459] receiving a first set of one or more cell configurations, wherein each cell configuration comprises cell configuration parameters for performing a conditional cell mobility procedure with a corresponding candidate target cell and comprises an execution condition regarding when to perform the conditional cell mobility procedure with the corresponding candidate target cell,

[0460] wherein at least one cell configuration for the corresponding candidate target cell includes a cell preconfiguration for another candidate target cell different from the corresponding candidate target cell, wherein the cell preconfiguration includes a cell configuration parameter for the UE to perform a conditional cell mobility procedure to the other candidate target cell when connected to the corresponding candidate target cell,

[0461] Evaluate the execution conditions of the first set of cell configurations,

[0462] When the execution condition of the corresponding candidate target cell in the first set of cell configurations is satisfied, performing a conditional cell mobility process with the corresponding candidate target cell based on the cell configuration parameters of the corresponding candidate target cell,

[0463] After successful completion of the conditional cell mobility procedure:

[0464] storing the cell pre-configuration for another candidate target cell as the cell configuration for another candidate target cell,

[0465] · releasing the first set of stored cell configurations, and

[0466] • Evaluate the execution conditions of the newly stored cell configuration for another candidate target cell.

[0467] exist Fig.25 A corresponding sequence diagram of exemplary UE behaviors according to the above-mentioned UE and UE method is shown in FIG.

[0468] Therefore, the above-mentioned improved mobility process achieves the purpose and overcomes some of the above-mentioned shortcomings. For example, the improved mobility process of the second technical solution involves that the UE has multiple cell configurations, which in turn include a pre-prepared cell configuration for another candidate cell. Accordingly, before performing the current conditional cell mobility process, the cell configuration for the potential future conditional cell mobility process for another candidate cell is already available at the UE and can be used by the UE immediately upon successful completion of the conditional cell mobility process. Therefore, the improved mobility process allows to speed up the subsequent conditional cell mobility process.

[0469] Some exemplary embodiments of the improved mobility procedure also involve improved base stations, in particular an improved source base station to which the UE is currently connected (referred to as, for example, a serving base station, since the base station 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 therein, as will be explained below.

[0470] Fig.26 A simplified and exemplary source base station structure according to an exemplary embodiment of the improved mobility process is shown, which can be based on a combination of Fig.13 The general base station structure explained above is implemented. Fig.26 The various structural elements of the source base station shown in the figure may be interconnected with each other, for example, using corresponding input / output nodes (not shown), for example, to exchange control and user data and other signals. Although not shown for illustrative purposes, the source base station may include additional structural elements.

[0471] As is apparent therefrom, the source base station comprises a cell configuration transmitter (the cell configuration comprises cell configuration parameters and execution conditions) and a cell configuration preparation circuit.

[0472] In the present case, as will become apparent from the following disclosure, the receiver of the source base station may therefore exemplarily be configured to at least partially perform one or more of the following operations: receiving requested cell configuration parameters, and receiving cell configurations of other candidate target cells, etc.

[0473] In the present case, as will become apparent from the following disclosure, the processing circuitry of the source base station may therefore exemplarily be configured to at least partially perform one or more of the following operations: determine cell configuration parameters, and generate a cell configuration, etc.

[0474] In the present case, as will become apparent from the following disclosure, the transmitter of the source base station may therefore be exemplarily configured to at least partially perform one or more of the following operations: sending a cell configuration to the UE, sending a request to a candidate target cell to request cell configuration parameters, etc.

[0475] An exemplary process as will be disclosed in further detail below is implemented by a source base station comprising the following items. Circuitry of 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 with a corresponding candidate target cell, and includes an execution condition regarding when to perform the conditional cell mobility procedure with the corresponding candidate target cell. At least one cell configuration for the corresponding candidate target cell includes a cell preconfiguration for another candidate target cell different from the corresponding candidate target cell. The cell preconfiguration includes cell configuration parameters used by the UE when connecting to the corresponding candidate target cell for performing the conditional cell mobility procedure to the other candidate target cell. A transmitter of the source base station sends the generated first set of one or more cell configurations to the UE.

[0476] The corresponding method comprises the following steps performed by the source base station:

[0477] generating a first set of one or more cell configurations, wherein each cell configuration comprises cell configuration parameters for performing a conditional cell mobility procedure with a corresponding candidate target cell and comprises an execution condition regarding when to perform the conditional cell mobility procedure with the corresponding candidate target cell,

[0478] wherein at least one cell configuration for the corresponding candidate target cell includes a cell preconfiguration for another candidate target cell different from the corresponding candidate target cell, wherein the cell preconfiguration includes a cell configuration parameter used by the UE when connected to the corresponding candidate target cell for performing a conditional cell mobility procedure to the other candidate target cell,

[0479] The generated first set of one or more cell configurations is sent to the UE.

[0480] exist Fig. 27 A corresponding sequence diagram of an exemplary source base station behavior consistent with the source base station and corresponding method discussed above is shown in . The sequence diagram shows an exemplary and simplified implementation of the source base station method presented above.

[0481] based on Fig.18 and Fig.19 , as described in detail for the first technical solution, the target base station can also participate in the second technical solution. Accordingly, the details of the target base station behavior will not be repeated here.

[0482] As explained above, an improved UE, an improved source base station and an improved target base station participate in an improved mobility procedure in order to achieve this objective, overcome some of the identified problems and achieve advantages.

[0483] The improved mobility process in which the improved device presented above participates according to the second technical solution will be explained below.

[0484] As already assumed above for the first technical solution, it is exemplarily assumed that the improved mobility process of the second technical solution is an improved conditional handover process (improved CHO process). However, this assumption of CHO as an improved conditional cell mobility process should not be understood as the improved mobility process should be limited to conditional handover. On the contrary, the principles based on the improved mobility process are also applicable to other conditional cell mobility processes, such as a conditional cell change process (e.g., see CPC above) and a conditional cell addition process (e.g., see CPA above).

[0485] Fig.28 It is a signaling diagram of an exemplary and simplified implementation of the improved CHO process according to the second technical solution, showing the message exchange between different participating entities (here UE, gNB0, gNB1 and gNB2) and the steps performed at these entities.

[0486] Assume that the UE is currently connected to the source gNB0. However, according to the improved CHO procedure, the source gNB's preparation for CHO is different from the corresponding CHO preparation in the prior art (see, for example, Fig. 9 and Fig.10 ) are significantly different. In addition, the CHO preparation used in the second technical solution has many similarities with the CHO preparation used in the first technical solution, but is also different from it, as will become apparent from the following.

[0487] As with the CHO preparation in the first technical solution, the CHO preparation for the second technical solution also involves preparing multiple CHO configurations for possible candidate target cells gNB1 and gNB2. Therefore, the multiple CHO configurations may include the CHO configuration to be used by the UE when it is connected to the source cell gNB0. In addition, however, according to the improved CHO process of the second solution, the multiple CHO configurations may also include the CHO configuration that the UE does not use now when it is connected to the source cell gNB0, but the UE will use in the future when it is connected to another serving cell (such as gNB1 or gNB2).

[0488] However, while the first technical solution is based on providing different CHO configurations in different subsets, the second technical solution relies on the concept of merging those CHO pre-configurations that the UE will potentially use in the future into those CHO configurations that the UE will use now.

[0489] For example, as explained in detail above for the first technical solution, for the second technical solution, the multiple CHO configurations initially prepared by the serving gNB0 may include the following:

[0490] CHO Configuration# Contents of cell configuration CHO Configuration 1 gNB1 CHO configuration@gNB0 CHO Configuration 2 gNB2CHO Configuration@gNB0 CHO Configuration 3 gNB0 CHO configuration@gNB1 CHO Configuration 4 gNB2 CHO configuration@gNB1

[0491] According to an exemplary option, the plurality of CHO configurations may further include:

[0492] CHO Configuration# Contents of cell configuration CHO Configuration 5 gNB0 CHO configuration@gNB2 CHO Configuration 6 gNB1 CHO configuration@gNB2

[0493] Therefore, the serving cell has prepared all necessary CHO configurations for the UE to use, including those CHO configurations that the UE is to use now when it is connected to the source cell, and including those CHO configurations that the UE is to use later when it is connected to another cell (be it gNB1 or gNB2).

[0494] According to an example, the source gNB0 may be combined with Fig.21 The above-discussed multiple CHO configurations are prepared in the corresponding manner explained for the first technical solution. Therefore, the improved CHO process of the second technical solution may also involve corresponding exchanges of preparation messages and pre-preparation messages between various gNBs for preparing multiple CHO configurations. Fig.21 The details are explained in conjunction with the CHO process of the first technical solution, and these details can also be conceptually applied to the improved CHO process of the second technical solution. Fig.21 Details of the improved CHO process are provided and will not be repeated here. However, in short, the improved CHO process of the second technical solution may accordingly include preparing a gNB0-related CHO configuration by the current serving cell of gNB0 based on CHO configuration parameters obtained from gNB1 and gNB2, respectively, and based on an execution condition determined by gNB0.

[0495] In addition, the improved CHO process of the second technical solution may also include pre-preparing gNB1-related CHO configurations for gNB2 and gNB0 at gNB1, for example, triggered by a CHO preparation message from gNB0. In addition, the improved CHO process of the second technical solution may also include pre-preparing gNB2-related CHO configurations for gNB1 and gNB0 at gNB2, for example, triggered by a CHO preparation message from gNB0. Then, the gNB1-related CHO configurations for gNB2 and gNB0 generated thereby and the gNB2-related CHO configurations for gNB0 and gNB1 generated thereby are sent to gNB0 by gNB1 and gNB2, respectively. Therefore, gNB0 has thus obtained the CHO configuration.

[0496] However, unlike the first technical solution, the serving cell does not send the CHO configuration thus obtained to the UE separately. Instead, according to the second technical solution, the source base station prepares the CHO configuration for gNB1 to include not only the configuration parameters and execution conditions for CHO to gNB1 (see CHO configuration 1 above), but also gNB1-related CHO pre-configurations for gNB0 and gNB2 (i.e., when the UE will be connected to gNB1, see CHO configurations 3 and 4 above). Therefore, the CHO configuration for gNB1 obtained thereby is extended by the CHO pre-configuration that the UE will use when performing the CHO configuration (in this example, CHO to gNB1).

[0497] Similarly, the CHO configuration for gNB2 includes not only the configuration parameters and execution conditions for CHO to gNB2 (see CHO configuration 2 above), but also gNB2-related CHO pre-configuration for gNB0 and gNB1 (i.e., when the UE is to be connected to gNB2, see CHO configurations 5 and 6 above).

[0498] Therefore, the serving cell gNB0 sends two extended CHO configurations for gNB1 and gNB2 to the UE.

[0499] As from Fig.28 It is obvious that after preparing two extended CHO configurations and sending them to the UE, the UE will continue to process the two extended CHO configurations for the potential CHO process. Accordingly, the UE will evaluate the execution conditions of gNB0-related CHO configurations 1 and 2 to determine whether some execution conditions of the CHO configurations are satisfied. gNB1-related CHO configurations 3 and 4 and gNB2-related CHO configurations 5 and 6, respectively stored in the gNB0-related CHO configuration, are not processed by the UE.

[0500] When the execution condition of an evaluated CHO configuration is met, the UE continues to perform the CHO procedure with the corresponding candidate target cell of the met CHO configuration. Fig.28 In the exemplary scenario, it is assumed that the UE performs the CHO process with the candidate target gNB1.

[0501] The CHO procedure may be performed based on the configuration parameters of the corresponding CHO configuration for gNB1. Therefore, the UE applies the CHO configuration for gNB1, thereby additionally adopting the gNB1-related CHO pre-configuration for gNB2 and gNB0 as the CHO configuration to be processed now when connecting to the new serving cell gNB1.

[0502] Therefore, CHO configurations 3 and 4 are immediately available at the UE to be processed when connected to the new serving cell gNB1. Therefore, a delay for performing subsequent CH incurring delay O is avoided, which would otherwise be caused by the required preparation of the new CHO configuration at the new serving cell gNB1. In addition, since the new serving cell gNB1 is not required to send the gNB1 related CHO configuration to the UE, the signaling overhead for the UE at the new serving cell is less.

[0503] In another optional implementation of the second technical solution, the UE may then release the previously stored CHO configurations, considering that these CHO configurations are no longer needed after the CHO to gNB1 is successful.

[0504] In a manner corresponding to the previous one, the UE may continue the CHO process at gNB1, which includes evaluating the execution conditions of gNB1-related CHO configurations 3 and 4 to determine whether some execution conditions are met.

[0505] Although not in Fig.28 , but the UE can perform another CHO procedure with gNB0 or ​​gNB2.

[0506] Other aspects

[0507] According to a first aspect, a user equipment is provided comprising the following items. A receiver receives a plurality of cell configurations from a source base station. Each cell configuration comprises cell configuration parameters for performing a conditional cell mobility procedure with a corresponding candidate target cell, and comprises an execution condition regarding when to perform the conditional cell mobility procedure. The plurality of cell configurations comprises a first subset of cell configurations to be evaluated by the UE when connected to the source base station. The plurality of cell configurations comprises a second subset of cell configurations to be evaluated by the UE when connected to a first candidate target cell among the plurality of candidate target cells, the first candidate target cell being different from a source cell of the source base station. The circuit of the UE evaluates only the execution conditions of the first subset of the cell configurations.

[0508] According to a second aspect provided in addition to the first aspect, the circuit, upon successfully completing a conditional cell mobility procedure between the UE and a first candidate target cell,

[0509] Maintaining the received multiple cell configuration, and

[0510] • Only the execution conditions of the second subset of cell configurations are evaluated.

[0511] In an optional embodiment, the circuit determines the second subset of cell configurations for evaluation based on:

[0512] • Based on the cell to which the UE is currently connected, wherein each subset of cell configurations within the plurality of cell configurations is associated with one cell.

[0513] • Indicating a subset of cell configurations to be evaluated by the UE based on the indication received from the first candidate target cell.

[0514] According to a third aspect provided in addition to the first or second aspect, evaluating only the first subset of cell configurations includes: the circuitry does not evaluate execution conditions of remaining cell configurations of the plurality of candidate target cells that do not belong to the first subset of cell configurations.

[0515] According to a fourth aspect provided in addition to one of the first to third aspects, the plurality of cell configurations comprises more than x cell configurations. In an optional embodiment, the plurality of cell configurations are organized in a sequence of cell configurations. The first subset of cell configurations comprises the cell configurations of the first x elements in the sequence. In another optional embodiment, the number of x is 8.

[0516] According to a fifth aspect provided in addition to one of the first to third aspects, the plurality of cell configurations comprises x cell configurations. The first subset of cell configurations comprises less than x cell configurations. In an optional embodiment, the number x is 8.

[0517] According to a sixth aspect provided in addition to one of the first to fifth aspects, a cell configuration belonging to a first subset is associated with an activated state, and wherein the remaining cell configurations of the plurality of cell configurations that do not belong to the first subset are associated with a deactivated state. In an optional embodiment, the UE does not evaluate the cell configuration associated with the deactivated state for performing the conditional cell mobility procedure, and wherein the UE evaluates the cell configuration associated with the activated state for performing the conditional cell mobility procedure.

[0518] According to a seventh aspect provided in addition to one of the first to sixth aspects, the plurality of cell configurations include more than one cell configuration associated with a candidate target cell. In an optional embodiment, the first subset includes one or more cell configurations, but less than all of the cell configurations of the plurality of cell configurations. In another optional embodiment, the cell configurations in the first subset are used for different candidate target cells, respectively. In an optional embodiment, the plurality of cell configurations include a subset of cell configurations for each cell configuration in the first subset.

[0519] According to an eighth aspect provided in addition to one of the first to seventh aspects, a receiver receives a cell status indication from a source base station, wherein the cell status indication indicates one or more candidate cells:

[0520] Its associated cell configuration is activated or deactivated.

[0521] In an optional implementation, the cell status indication is carried:

[0522] In a Radio Resource Control (RRC) message, or

[0523] • In the Control element of a Medium Access Control (MAC) message.

[0524] In an optional embodiment, the cell state indication is a bitmap, wherein each bit of the bitmap is associated with a candidate target cell among a plurality of candidate target cells, and one value of the bit indicates activation of the cell configuration of the associated candidate target cell, and another value of the bit indicates deactivation of the cell configuration of the associated candidate target cell.

[0525] According to a ninth aspect provided in addition to the first to eighth aspects, the conditional cell mobility procedure is one of the following:

[0526] Conditional handover, according to which the UE disconnects from the source cell and connects to a candidate target cell when an execution condition is met, optionally wherein the source cell and the target cell belong to the same primary cell group of the UE,

[0527] a conditional cell change, according to which the UE disconnects from a source cell and connects to a candidate target cell when an execution condition is met, wherein the source cell and the candidate target cell belong to a secondary cell group of the UE, the secondary cell group of the UE being different from the primary cell group of the UE, and

[0528] Conditional cell addition, according to which the UE is connected to a candidate target cell when an execution condition is met, wherein the candidate target is a primary cell in a secondary cell group of the UE, and the secondary cell group of the UE is different from the primary cell group of the UE.

[0529] According to a tenth aspect provided in addition to one of the first to ninth aspects, a cell configuration parameter of the cell configuration includes one or more of the following:

[0530] The radio resource configuration of the candidate target cell, such as resource blocks, physical channel configuration,

[0531] ·Security configuration of candidate target cells,

[0532] Dual connection information, such as primary cell group information, secondary cell group information,

[0533] · Measurement configuration of candidate target cells,

[0534] Mobility configuration.

[0535] In an optional embodiment, the execution condition for when to perform the conditional cell mobility procedure includes one or more sub-conditions, one or all of which must be satisfied for the execution condition to be satisfied. In another option, the sub-condition relates to the communication quality of one or more of the source cell and the candidate target cell associated with the execution condition.

[0536] According to an eleventh aspect provided in addition to one of the first to tenth aspects, each cell configuration of the first subset includes cell configuration parameters and execution conditions for performing a conditional cell mobility procedure from a source cell to a corresponding candidate target cell. Each cell configuration of the second subset includes cell configuration parameters and execution conditions for performing a conditional cell mobility procedure from the first candidate target cell to a corresponding candidate target cell.

[0537] According to a twelfth aspect provided in addition to one of the first to eleventh aspects, the UE is configured with a primary cell group MCG and multiple secondary cell groups SCG. Only one SCG of the multiple SCGs is active for the UE at a given time, so that the UE is connected to one or more cells of the active SCG. In an optional embodiment, the circuit determines the active SCG as the first SCG configured for the UE. The circuit determines the active SCG based on an indication received from a source base station.

[0538] According to a thirteenth aspect provided in addition to the twelfth aspect, configuring an MCG and a plurality of SCGs for a UE includes:

[0539] - The receiver receives configuration information for the MCG and at least one of the plurality of SCGs from the source base station, optionally wherein the configuration information for the plurality of SCGs is received in a radio resource control, RRC, message.

[0540] In an optional implementation, the configuration information includes one or more of the following:

[0541] ° Common cell IDs of the cells of the corresponding cell group,

[0542] ° the common frequency range of the cells of the corresponding cell group, and

[0543] ° Common radio resources of the cells of the corresponding cell group.

[0544] In an optional implementation manner, the configuration information of the SCG includes:

[0545] ° List of candidate cells used for evaluation of conditional cell mobility procedure when SCG is activated.

[0546] According to a fourteenth aspect provided in addition to the twelfth or thirteenth aspect, the circuit performs one or more of the following processes on an active SCG but not on a deactivated SCG:

[0547] ° Random access to the cell of the corresponding SCG,

[0548] ° Radio link measurements with the cells of the corresponding SCG,

[0549] °Uplink synchronization with the cell of the corresponding SCG.

[0550] According to a fifteenth aspect provided in addition to one of the twelfth to fourteenth aspects, each SCG of the plurality of SCGs is identified by:

[0551] ° a combination of an identifier of a primary cell of the corresponding SCG and an identifier of a radio resource used for transmission and reception by a cell of the corresponding SCG, optionally wherein the identifier of the radio resource is an Absolute Radio Frequency Channel Number ARFCN, or

[0552] ° SCG identifier used to distinguish between multiple SCGs.

[0553] According to the sixteenth aspect provided in addition to one of the twelfth to fifteenth aspects, the UE stores information associating each SCG of a plurality of SCGs with a cell. Upon successful completion of a conditional cell mobility procedure to a candidate target cell, the circuit determines the SCG associated with the candidate target cell of the completed conditional cell mobility procedure based on the stored information. In an optional embodiment, the circuit uses configuration information of the determined SCG.

[0554] According to the seventeenth aspect, a base station is provided that includes the following items. The circuit of the base station generates multiple cell configurations for multiple candidate target cells. Each cell configuration includes cell configuration parameters for performing a conditional cell mobility procedure between a user equipment UE and the corresponding candidate target cell, and includes an execution condition regarding when to perform the conditional cell mobility procedure with the corresponding candidate target cell. The multiple cell configurations include a first subset of cell configurations to be evaluated by the UE when connected to the base station. The multiple cell configurations include a second subset of cell configurations to be evaluated when the UE is connected to a first candidate target cell among the multiple candidate target cells, the first candidate target cell being different from a source cell of the base station. The transmitter of the base station sends the generated multiple cell configurations to the UE.

[0555] According to an eighteenth aspect provided in addition to the seventeenth aspect, generating a plurality of cell configurations includes:

[0556] The transmitter sends a request for requesting a cell configuration parameter of the first candidate target cell to the first candidate target cell,

[0557] The receiver receives, from the first candidate target cell, a cell configuration of at least another candidate target cell in response to the request, wherein the cell configuration of the another candidate target cell includes cell configuration parameters of the another candidate target cell to be used by the UE when connected to the first candidate target cell, and includes an execution condition regarding when the UE performs a conditional cell mobility procedure between the another candidate target cell and the another candidate target cell when connected to the first candidate target cell.

[0558] In an optional embodiment, the receiver receives the requested cell configuration parameters of the first candidate target cell from the first candidate target cell, and the circuit determines, for the requested cell configuration parameters of the first candidate target cell, an execution condition regarding when to perform a conditional cell mobility procedure between the UE and the first candidate target cell. In another optional embodiment, 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.

[0559] According to the nineteenth aspect provided in addition to the seventeenth or eighteenth aspect, the transmitter sends a cell status indication to the UE. The cell status indication indicates one or more of the following:

[0560] · Associated cell configurations are activated candidate cells,

[0561] Candidate cells whose associated cell configuration is deactivated.

[0562] In an optional implementation, the cell status indication is carried:

[0563] In a Radio Resource Control (RRC) message, or

[0564] • In the Control element of a Medium Access Control (MAC) message.

[0565] In another optional embodiment, the cell status indication is a bitmap, wherein each bit of the bitmap is associated with a candidate target cell among multiple candidate target cells, and one value of the bit indicates activation of the cell configuration of the associated candidate target cell, and another value of the bit indicates deactivation of the cell configuration of the associated candidate target cell.

[0566] According to the 20th aspect provided in addition to one of the seventeenth to nineteenth aspects, the UE is configured with a primary cell group MCG and multiple secondary cell groups SCG. Only one of the secondary cell groups is active for the UE at a given time, so that the UE is connected to one or more cells of the active secondary cell group. The transmitter sends an indication to the UE indicating which secondary cell group is active.

[0567] According to the 21st aspect provided in addition to the 20th aspect, the transmitter sends configuration information for at least one of the primary cell group and the plurality of secondary cell groups to the UE. In an optional embodiment, the configuration information for the plurality of SCGs is sent in a radio resource control RRC message. In an optional embodiment, the configuration information includes one or more of the following:

[0568] ° Common cell IDs of the cells of the corresponding cell group,

[0569] ° the common frequency range of the cells of the corresponding cell group, and

[0570] ° Common radio resources of the cells of the corresponding cell group.

[0571] In another optional implementation, the configuration information of the SCG includes:

[0572] ° List of candidate cells used for evaluation of conditional cell mobility procedure when SCG is activated.

[0573] According to aspect 22, there is provided a base station comprising the following items. A receiver of the base station receives a request from a source base station for requesting cell configuration parameters of the base station to perform a conditional cell mobility procedure between a user equipment UE connected to the source base station and the base station. In response to receiving the request, a circuit of the base station generates a cell configuration of at least another candidate target cell. The cell configuration of the another candidate target cell includes the cell configuration parameters of the another candidate target cell to be used by the UE when connected to the base station, and includes an execution condition regarding when to perform conditional cell mobility between the UE and the another candidate target cell when connected to the base station. The transmitter of the base station sends the generated cell configuration for at least another candidate target cell to the source base station.

[0574] According to a 23rd aspect provided in addition to the 22nd aspect, generating a cell configuration for at least another candidate target cell comprises:

[0575] The transmitter sends a request for a cell configuration parameter of another candidate target cell to another candidate target cell,

[0576] The receiver receives the requested cell configuration parameters of another candidate target cell from the another candidate target cell,

[0577] The circuit determines an execution condition regarding when to perform a conditional mobility procedure between the UE and the another candidate target cell while connected to the base station.

[0578] According to a 24th aspect provided in addition to the 22nd or 23rd aspect, the transmitter sends an indication to the UE indicating a subset of cell configurations to be evaluated by the UE.

[0579] According to the 25th aspect provided in addition to one of the 22nd to 24th aspects, the circuit generates the requested cell configuration parameter of the base station in response to receiving the request. The transmitter transmits the generated cell configuration parameter of the base station to the source base station.

[0580] According to aspect 26, there is provided a method comprising the following steps performed by a user equipment UE:

[0581] receiving, from a source base station, a plurality of cell configurations for a plurality of candidate target cells, wherein each cell configuration comprises a cell configuration parameter for performing a conditional cell mobility procedure with a corresponding candidate target cell and comprises an execution condition regarding when to perform the conditional cell mobility procedure with the corresponding candidate target cell,

[0582] wherein the multiple cell configurations include a first subset of cell configurations to be evaluated by the UE when connected to the source base station, wherein the multiple cell configurations include a second subset of cell configurations to be evaluated by the UE when connected to a first candidate target cell among the multiple candidate target cells, the first candidate target cell being different from the source cell of the source base station,

[0583] Only the execution conditions of the first subset of cell configurations are evaluated,

[0584] When an execution condition of a cell configuration in the first subset of the evaluated cell configurations is satisfied for the first candidate target cell, a conditional cell mobility procedure with the first candidate target cell is performed based on the cell configuration parameters of the first candidate target cell.

[0585] According to aspect 27, there is provided a method comprising the following steps performed by a base station:

[0586] generating a plurality of cell configurations for a plurality of candidate target cells, wherein each cell configuration comprises cell configuration parameters for performing a conditional cell mobility procedure between a user equipment UE and the corresponding candidate target cell, and comprises an execution condition on when to perform the conditional cell mobility procedure with the corresponding candidate target cell,

[0587] wherein the plurality of cell configurations comprises a first subset of cell configurations to be evaluated by the UE when connected to the base station, wherein the plurality of cell configurations comprises a second subset of cell configurations to be evaluated by the UE when connected to a first candidate target cell among the plurality of candidate target cells, the first candidate target cell being different from a source cell of the base station,

[0588] The generated multiple cell configurations are sent to the UE.

[0589] According to aspect 28, there is provided a method comprising the following steps performed by a base station:

[0590] receiving a request for requesting a cell configuration parameter of the base station from the source base station, the cell configuration parameter being used to perform a conditional cell mobility procedure between a user equipment UE connected to the source base station and the base station,

[0591] generating, in response to receiving the request, a cell configuration of at least another candidate target cell, wherein the cell configuration of the another candidate target cell comprises cell configuration parameters of the another candidate target cell to be used by the UE when connected to the base station, and comprises an execution condition regarding when to perform conditional cell mobility between the UE and the another candidate target cell when connected to the base station,

[0592] The generated cell configuration for at least another candidate target cell is sent to the source base station.

[0593] According to aspect 29, there is provided an integrated circuit controlling a process of a user equipment UE, the process comprising the following steps performed by the UE:

[0594] receiving, from a source base station, a plurality of cell configurations for a plurality of candidate target cells, wherein each cell configuration comprises a cell configuration parameter for performing a conditional cell mobility procedure with a corresponding candidate target cell and comprises an execution condition regarding when to perform the conditional cell mobility procedure with the corresponding candidate target cell,

[0595] wherein the multiple cell configurations include a first subset of cell configurations to be evaluated by the UE when connected to the source base station, wherein the multiple cell configurations include a second subset of cell configurations to be evaluated by the UE when connected to a first candidate target cell among the multiple candidate target cells, the first candidate target cell being different from the source cell of the source base station,

[0596] Only the execution conditions of the first subset of cell configurations are evaluated,

[0597] When an execution condition of a cell configuration in the first subset of the evaluated cell configurations is satisfied for the first candidate target cell, a conditional cell mobility procedure with the first candidate target cell is performed based on the cell configuration parameters of the first candidate target cell.

[0598] According to aspect 30, there is provided an integrated circuit controlling a process of a base station, the process comprising the following steps performed by the base station:

[0599] generating a plurality of cell configurations for a plurality of candidate target cells, wherein each cell configuration comprises cell configuration parameters for performing a conditional cell mobility procedure between a user equipment UE and the corresponding candidate target cell, and comprises an execution condition on when to perform the conditional cell mobility procedure with the corresponding candidate target cell,

[0600] wherein the plurality of cell configurations comprises a first subset of cell configurations to be evaluated by the UE when connected to the base station, wherein the plurality of cell configurations comprises a second subset of cell configurations to be evaluated by the UE when connected to a first candidate target cell among the plurality of candidate target cells, the first candidate target cell being different from a source cell of the base station,

[0601] The generated multiple cell configurations are sent to the UE.

[0602] According to aspect 31, there is provided an integrated circuit controlling a process of a base station, the process comprising the following steps performed by the base station:

[0603] receiving a request for requesting a cell configuration parameter of the base station from the source base station, the cell configuration parameter being used to perform a conditional cell mobility procedure between a user equipment UE connected to the source base station and the base station,

[0604] generating, in response to receiving the request, a cell configuration of at least another candidate target cell, wherein the cell configuration of the another candidate target cell comprises cell configuration parameters of the another candidate target cell to be used by the UE when connected to the base station, and comprises an execution condition regarding when to perform conditional cell mobility between the UE and the another candidate target cell when connected to the base station,

[0605] The generated cell configuration for at least another candidate target cell is sent to the source base station.

[0606] According to aspect 32, a user equipment UE is provided, comprising the following items. A receiver of the UE receives a first set of one or more cell configurations. Each cell configuration comprises cell configuration parameters for performing a conditional cell mobility procedure with a corresponding candidate target cell, and comprises an execution condition regarding when to perform the conditional cell mobility procedure with the corresponding candidate target cell. At least one cell configuration for the corresponding candidate target cell comprises a cell pre-configuration for another candidate target cell different from the corresponding candidate target cell. The cell pre-configuration comprises cell configuration parameters for performing a conditional cell mobility procedure to another candidate target cell used by the UE when connected to the corresponding candidate target cell. A circuit of the UE evaluates the execution condition of the first set of cell configurations. When the execution condition of the corresponding candidate target cell in the first set of cell configurations is met, the circuit performs the conditional cell mobility procedure with the corresponding candidate target cell based on the cell configuration parameters of the corresponding candidate target cell. Upon successful completion of the conditional cell mobility procedure, the circuit:

[0607] storing the cell pre-configuration for another candidate target cell as the cell configuration for another candidate target cell,

[0608] · releasing the first set of stored cell configurations, and

[0609] • Evaluate the execution conditions of the newly stored cell configuration against another candidate target cell.

[0610] According to aspect 33, a base station is provided comprising the following items. The circuit 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 with a corresponding candidate target cell, and includes an execution condition regarding when to perform the conditional cell mobility procedure with the corresponding candidate target cell. At least one cell configuration for the corresponding candidate target cell includes a cell preconfiguration for another candidate target cell different from the corresponding candidate target cell. The cell preconfiguration includes cell configuration parameters for performing a conditional cell mobility procedure to another candidate target cell used by the UE when connected to the corresponding candidate target cell. The transmitter of the base station sends the generated first set of one or more cell configurations to the UE.

[0611] According to a 34th aspect provided in addition to the above 33rd aspect, generating a first set of one or more cell configurations comprises:

[0612] The transmitter sends a request for requesting a cell configuration parameter of the first candidate target cell to the first candidate target cell,

[0613] The receiver receives, from the first candidate target cell, a cell configuration of at least another candidate target cell in response to the request, wherein the cell configuration of the another candidate target cell includes cell configuration parameters of the another candidate target cell to be used by the UE when connected to the first candidate target cell, and includes an execution condition regarding when to perform a conditional cell mobility procedure between the UE and the another candidate target cell when connected to the first candidate target cell.

[0614] In an optional embodiment, the receiver receives the requested cell configuration parameters of the first candidate target cell from the first candidate target cell, and the circuit determines, for the requested cell configuration parameters of the first candidate target cell, an execution condition regarding when to perform a conditional cell mobility procedure between the UE and the first candidate target cell. In an optional embodiment, the circuit generates a cell configuration for the first candidate target cell by including the following items:

[0615] The cell configuration parameters of the first candidate target cell received from the first candidate target cell, and the determined execution condition for the first candidate target cell;

[0616] • A cell configuration of another candidate target cell received from the first candidate target cell.

[0617] According to aspect 35, there is provided a method comprising the following steps performed by a user equipment UE:

[0618] receiving a first set of one or more cell configurations, wherein each cell configuration comprises cell configuration parameters for performing a conditional cell mobility procedure with a corresponding candidate target cell and comprises an execution condition regarding when to perform the conditional cell mobility procedure with the corresponding candidate target cell,

[0619] wherein at least one cell configuration for the corresponding candidate target cell includes a cell preconfiguration for another candidate target cell different from the corresponding candidate target cell, wherein the cell preconfiguration includes a cell configuration parameter for the UE to use when connected to the corresponding candidate target cell to perform a conditional cell mobility procedure to the other candidate target cell,

[0620] Evaluate the execution conditions of the first set of cell configurations,

[0621] When the execution condition of the corresponding candidate target cell in the first set of cell configurations is satisfied, the circuit performs a conditional cell mobility process with the corresponding candidate target cell based on the cell configuration parameters of the corresponding candidate target cell,

[0622] Upon successful completion of the Conditional Cell Mobility procedure:

[0623] storing the cell pre-configuration for another candidate target cell as the cell configuration for another candidate target cell,

[0624] · releasing the first set of stored cell configurations, and

[0625] • Evaluate the execution conditions of the newly stored cell configuration against another candidate target cell.

[0626] According to aspect 36, there is provided a method comprising the following steps performed by a base station:

[0627] generating a first set of one or more cell configurations, wherein each cell configuration comprises cell configuration parameters for performing a conditional cell mobility procedure with a corresponding candidate target cell and comprises an execution condition regarding when to perform the conditional cell mobility procedure with the corresponding candidate target cell,

[0628] wherein at least one cell configuration for the corresponding candidate target cell includes a cell preconfiguration for another candidate target cell different from the corresponding candidate target cell, wherein the cell preconfiguration includes a cell configuration parameter for the UE to use when connected to the corresponding candidate target cell to perform a conditional cell mobility procedure to the other candidate target cell,

[0629] The generated first set of one or more cell configurations is sent to the UE.

[0630] According to aspect 37, there is provided an integrated circuit controlling a process of a user equipment UE, the process comprising the following steps performed by the UE:

[0631] receiving a first set of one or more cell configurations, wherein each cell configuration comprises cell configuration parameters for performing a conditional cell mobility procedure with a corresponding candidate target cell and comprises an execution condition regarding when to perform the conditional cell mobility procedure with the corresponding candidate target cell,

[0632] wherein at least one cell configuration for the corresponding candidate target cell includes a cell preconfiguration for another candidate target cell different from the corresponding candidate target cell, wherein the cell preconfiguration includes a cell configuration parameter for the UE to use when connected to the corresponding candidate target cell to perform a conditional cell mobility procedure to the other candidate target cell,

[0633] Evaluate the execution conditions of the first set of cell configurations,

[0634] When the execution condition of the corresponding candidate target cell in the first set of cell configurations is satisfied, the circuit performs a conditional cell mobility process with the corresponding candidate target cell based on the cell configuration parameters of the corresponding candidate target cell,

[0635] Upon successful completion of the Conditional Cell Mobility procedure:

[0636] storing the cell pre-configuration for another candidate target cell as the cell configuration for another candidate target cell,

[0637] · releasing the first set of stored cell configurations, and

[0638] • Evaluate the execution conditions of the newly stored cell configuration against another candidate target cell.

[0639] According to aspect 38, there is provided an integrated circuit controlling a process of a base station, the process comprising the following steps performed by the base station:

[0640] generating a first set of one or more cell configurations, wherein each cell configuration comprises cell configuration parameters for performing a conditional cell mobility procedure with a corresponding candidate target cell and comprises an execution condition regarding when to perform the conditional cell mobility procedure with the corresponding candidate target cell,

[0641] wherein at least one cell configuration for the corresponding candidate target cell includes a cell preconfiguration for another candidate target cell different from the corresponding candidate target cell, wherein the cell preconfiguration includes a cell configuration parameter for the UE to use when connected to the corresponding candidate target cell to perform a conditional cell mobility procedure to the other candidate target cell,

[0642] The generated first set of one or more cell configurations is sent to the UE.

[0643] Further variations, including hardware and software implementations of the present disclosure

[0644] The present disclosure can be implemented by software, hardware or software in collaboration with hardware. Each functional block used in the description of each of the above embodiments can be implemented in part or in whole by an LSI such as an integrated circuit, and each process described in each embodiment can be controlled in part or in whole by the same LSI or a combination of LSIs. LSI can be formed as a chip alone, or a chip can be formed to include a part or all of the functional blocks. LSI may include data input and output coupled thereto. The LSI here may be referred to as IC (integrated circuit), system LSI, super LSI or ultra LSI according to the difference in integration. However, the technology for implementing integrated circuits is not limited to LSI, and can be implemented by using a dedicated circuit, a general-purpose processor or a dedicated processor. In addition, an FPGA (field programmable gate array) that can be programmed after LSI manufacturing or a reconfigurable processor that can reconfigure the connection and setting of the circuit unit arranged inside the LSI can be used. The present disclosure can be implemented as digital processing or analog processing. If future integrated circuit technology replaces LSI due to the advancement of semiconductor technology or other derivative technologies, the functional blocks can be integrated using future integrated circuit technology. Biotechnology can also be applied.

[0645] The present disclosure may be implemented by any kind of device, apparatus, or system having a communication function, which is referred to as a communication device.

[0646] The communication device may include a transceiver and a processing / control circuit. The transceiver may include and / or function as a receiver and a transmitter. As a transmitter and a receiver, the transceiver may include an RF (radio frequency) module and one or more antennas, and the RF module may include an amplifier, an RF modulator / demodulator, etc.

[0647] Some non-limiting examples of such communication devices include phones (e.g., cellular (cell) phones, smart phones), tablets, personal computers (PCs) (e.g., laptops, desktops, netbooks), 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, digital book readers, telemedicine / telemedicine (remote health and medicine) devices, and vehicles providing communication capabilities (e.g., cars, airplanes, ships), and various combinations thereof.

[0648] Communication devices are not limited to portable or movable, and may also include any kind of device, equipment, or system that is non-portable or fixed, such as smart home devices (e.g., appliances, lighting, smart meters, control panels), vending machines, and any other "things" in a network of the Internet of Things (IoT).

[0649] Communications may include exchanging data via, for example, cellular systems, wireless LAN systems, satellite systems, etc., and various combinations thereof.

[0650] The communication device may include a device such as a controller or a sensor that is coupled to a communication device that performs the communication functions described in the present disclosure. For example, the communication device may include a controller or a sensor that generates a control signal or a data signal that is used by the communication device that performs the communication functions of the communication device.

[0651] Communications devices may also include infrastructure facilities such as base stations, access points, and any other device, equipment, or system that communicates with or controls devices such as those in the above non-limiting examples.

[0652] (Control signal)

[0653] In the present disclosure, the downlink control signal (information) related to the present disclosure may be a signal (information) transmitted through the PDCCH of the physical layer, or may be a signal (information) transmitted through a higher layer MAC control element (CE) or RRC. The downlink control signal may be a predefined signal (information).

[0654] The uplink control signal (information) related to the present disclosure may be a signal (information) transmitted through the PUCCH of the physical layer, or may be a signal (information) transmitted through the MAC CE or RRC of a higher layer. In addition, the uplink control signal may be a predefined signal (information). The uplink control signal may be replaced by uplink control information (UCI), first-stage sidelink control information (SCI), or second-stage SCI.

[0655] (Base Station)

[0656] 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 station unit, or a gateway. In addition, in side link communication, a terminal may be used instead of a base station. A base station may be a relay device that relays communication between a higher node and a terminal. A base station may also be a roadside unit.

[0657] (Uplink / Downlink / Sidelink)

[0658] The present disclosure may be applied to any one of an uplink, a downlink, and a sidelink.

[0659] The present disclosure can be applied to, for example, uplink channels (such as PUSCH, PUCCH and PRACH), downlink channels (such as PDSCH, PDCCH and PBCH), and sidelink channels (such as physical sidelink shared channel (PSSCH), physical sidelink control channel (PSCCH) and physical sidelink broadcast channel (PSBCH)).

[0660] PDCCH, PDSCH, PUSCH and PUCCH are examples of downlink control channels, downlink data channels, uplink data channels and uplink control channels, respectively. PSCCH and PSSCH are examples of sidelink control channels and sidelink data channels, respectively. PBCH and PSBCH are examples of broadcast channels, respectively, and PRACH is an example of a random access channel.

[0661] (Data Channel / Control Channel)

[0662] The present disclosure may be applied to any one of a data channel and a control channel. The channels in the present disclosure may be replaced by data channels including PDSCH, PUSCH and PSSCH and / or control channels including PDCCH, PUCCH, PBCH, PSCCH and PSBCH.

[0663] (Reference signal)

[0664] In the present 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 sometimes referred to as a pilot signal. The reference signal may be any one 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).

[0665] (Time interval)

[0666] In the present disclosure, the time resource unit is not limited to one or a combination of a time slot and a symbol, and may be a time resource unit such as a frame, a superframe, a subframe, a time slot, a time slot subslot, a small time slot, or a time resource unit such as a symbol, an orthogonal frequency division multiplexing (OFDM) symbol, a single carrier-frequency division multiplexing access (SC-FDMA) symbol, or other time resource units. The number of symbols included in a time slot is not limited to any number of symbols exemplified in the above (s) embodiment, and may be other numbers of symbols.

[0667] (frequency band)

[0668] The present disclosure may be applied to any of the licensed and unlicensed frequency bands.

[0669] (communication)

[0670] The present disclosure can be applied to any one of the communication between a base station and a terminal (Uu-link communication), the communication between a terminal and a terminal (Sidelink communication), and the vehicle-to-everything (V2X) communication. The channels in the present disclosure can be replaced by PSCCH, PSSCH, physical sidelink feedback channel (PSFCH), PSBCH, PDCCH, PUCCH, PDSCH, PUSCH, and PBCH.

[0671] In addition, the present disclosure can also be applied to any network in a terrestrial network or a network other than a terrestrial network using a satellite or a high altitude pseudo satellite (HAPS) (NTN: Non-Terrestrial Network). In addition, the present disclosure can be applied to a network with a large cell size, and a terrestrial network with a large delay compared to a symbol length or a time slot length, such as an ultra-wideband transmission network.

[0672] (Antenna port)

[0673] An antenna port refers to a logical antenna (antenna group) formed by one or more physical antennas. That is, an antenna port does not necessarily refer to one physical antenna, and sometimes refers to an array antenna formed by multiple antennas, etc. For example, it is not defined how many physical antennas form an antenna port, but the antenna port is defined as the minimum unit through which the terminal is allowed to send a reference signal. The antenna port can also be defined as the minimum unit for multiplication of precoding vector weights.

[0674] Furthermore, various embodiments may also be implemented by means of software modules executed by a processor or directly in hardware. Combinations of software modules and hardware implementations are also possible. Software modules may be stored on any kind of computer-readable storage medium, such as RAM, EPROM, EEPROM, flash memory, registers, hard disk, CD-ROM, DVD, etc. It should also be noted that individual features of different embodiments may be the subject of another embodiment, either alone or in any combination.

[0675] Those skilled in the art will appreciate that many changes and / or modifications may be made to the present disclosure as shown in the specific embodiments. Therefore, the present embodiments are to be considered in all aspects as illustrative and not restrictive.

Claims

1. A user equipment UE, comprising: a receiver that receives, from a source base station, a plurality of cell configurations for a plurality of candidate target cells, wherein each cell configuration includes cell configuration parameters and execution conditions for a conditional cell mobility procedure, The multiple cell configurations include a first subset of cell configurations to be used when connecting to the source base station, and a second subset of cell configurations to be used when connecting to a first candidate target cell among the multiple candidate target cells, circuitry that evaluates execution conditions of a first subset of said cell configurations, The circuit performs a conditional cell mobility procedure with the first candidate target cell based on cell configuration parameters of the first candidate target cell when an execution condition of the evaluated first subset of the cell configurations is satisfied for the first candidate target cell.

2. The UE according to claim 1, wherein: The circuit, upon successfully completing the conditional cell mobility procedure between the UE and the first candidate target cell: Maintaining the received multiple cell configuration, and evaluating execution conditions of a second subset of said cell configurations, Optionally, the circuit determines the second subset of the cell configurations to be evaluated based on: • Based on a cell to which the UE is currently connected, wherein each subset of cell configurations within the plurality of cell configurations is associated with one cell. • Indicating a subset of cell configurations to be evaluated by the UE based on the indication received from the first candidate target cell.

3. The UE according to claim 1 or 2, wherein: Evaluating the first subset of cell configurations includes: the circuitry does not evaluate execution conditions of remaining cell configurations of the plurality of candidate target cells that do not belong to the first subset of cell configurations.

4. The UE according to any one of claims 1 to 3, wherein: The plurality of cell configurations comprises more than x cell configurations, Optionally, wherein the plurality of cell configurations are organized in a sequence of cell configurations, and wherein the first subset of the cell configurations comprises a first group of x elements of the cell configurations in the sequence, Optionally, the number of x is 8.

5. The UE according to any one of claims 1 to 3, wherein: The multiple cell configurations include x cell configurations, wherein the first subset of cell configurations includes less than the x cell configurations, Optionally, the number of x is 8.

6. The UE according to any one of claims 1 to 5, wherein: The cell configurations belonging to the first subset are associated with an activated state, and wherein the remaining cell configurations of the plurality of cell configurations that do not belong to the first subset are associated with a deactivated state, Optionally, a cell configuration associated with the deactivated state is not evaluated by the UE for performing the conditional cell mobility procedure, and a cell configuration associated with the activated state is evaluated by the UE for performing the conditional cell mobility procedure.

7. The UE according to any one of claims 1 to 6, wherein: The plurality of cell configurations include more than one cell configuration associated with one candidate target cell, Optionally, the first subset includes one or more cell configurations, but less than all cell configurations of the multiple cell configurations, Optionally, the cell configurations in the first subset are respectively used for different candidate target cells, Optionally, the plurality of cell configurations comprises a subset of cell configurations for each cell configuration in the first subset.

8. The UE according to any one of claims 1 to 7, wherein the receiver receives a cell status indication from the source base station, wherein the cell status indication indicates one or more candidate cells: Its associated cell configuration is activated or deactivated, Optionally, the cell status indication is carried: In a Radio Resource Control (RRC) message, or In the control element of the medium access control MAC message, Optionally, the cell status indication is a bitmap, wherein each bit of the bitmap is associated with a candidate target cell among the multiple candidate target cells, and one value of the bit indicates activation of the cell configuration of the associated candidate target cell, and another value of the bit indicates deactivation of the cell configuration of the associated candidate target cell.

9. The UE according to any one of claims 1 to 8, wherein: The conditional cell mobility procedure is one of the following: Conditional switching, according to which the UE disconnects from the source cell and connects to a candidate target cell when the execution condition is met, optionally wherein the source cell and the target cell belong to the same primary cell group of the UE, a conditional cell change, according to which the UE disconnects from the source cell and connects to a candidate target cell when the execution condition is met, wherein the source cell and the candidate target cell belong to a secondary cell group of the UE, the secondary cell group of the UE being different from the primary cell group of the UE, and Conditional cell addition, according to which the UE is connected to a candidate target cell when the execution condition is met, wherein the candidate target is a primary cell in a secondary cell group of the UE, the secondary cell group of the UE being different from the primary cell group of the UE.

10. The UE according to any one of claims 1 to 9, wherein: The cell configuration parameters of the cell configuration include one or more of the following: the radio resource configuration of the candidate target cell, such as resource blocks, physical channel configuration, · security configuration of the candidate target cell, Dual connectivity information, such as primary cell group information and secondary cell group information, · measurement configuration of the candidate target cell, Mobility configuration, Optionally, the execution condition regarding when to execute the conditional cell mobility process includes one or more sub-conditions, one or all of the one or more sub-conditions must be met so that the execution condition is met, and optionally, the sub-conditions relate to the communication quality of one or more of the source cell and the candidate target cells related to the execution condition.

11. The UE according to any one of claims 1 to 10, wherein: Each cell configuration of the first subset comprises cell configuration parameters and the execution condition of a conditional cell mobility procedure from the source cell to a corresponding candidate target cell, Each cell configuration of the second subset includes cell configuration parameters and the execution condition of the conditional cell mobility process from the first candidate target cell to the corresponding candidate target cell.

12. The UE according to any one of claims 1 to 11, wherein: The UE is configured with a primary cell group MCG and a plurality of secondary cell groups SCG, wherein one SCG of the plurality of SCGs is active for the UE at a given time, so that the UE is connected to one or more cells of the active SCG, Optionally, the circuit determines the active SCG as the first SCG configured for the UE, Optionally, the circuit determines the active SCG based on an indication received from the source base station.

13. The UE according to claim 12, wherein: The UE is configured with the MCG and the multiple SCGs, including: - the receiver receives configuration information for the MCG and at least one of the plurality of SCGs from the source base station, optionally wherein the configuration information for the plurality of SCGs is received in a Radio Resource Control (RRC) message, -Optionally, the configuration information includes one or more of the following: ° Common cell IDs of cells of the corresponding cell group, ° the common frequency range of the cells of the corresponding cell group, and ° common radio resources of cells of the corresponding cell group, -Optionally, the configuration information of the SCG includes: ° List of candidate cells for evaluating the conditional cell mobility process when the SCG is activated.

14. The UE according to claim 12 or 13, wherein: The circuit performs one or more of the following processes on the active SCG: ° Random access to the cell of the corresponding SCG, ° Radio link measurements with the cells of the corresponding SCG, °Uplink synchronization with the cell of the corresponding SCG.

15. The UE according to any one of claims 12 to 14, wherein: Each SCG in the plurality of SCGs is identified by: ° a combination of an identifier of a primary cell of the corresponding SCG and an identifier of a radio resource used by a cell of the corresponding SCG for transmission and reception, optionally wherein the identifier of the radio resource is an Absolute Radio Frequency Channel Number ARFCN, or ° An SCG identifier used to distinguish between the multiple SCGs.

16. The UE according to any one of claims 12 to 15, wherein: the UE stores information associating each of the plurality of SCGs with a cell, wherein upon successful completion of the conditional cell mobility procedure to a candidate target cell, the circuitry determines the SCG associated with the candidate target cell of the completed conditional cell mobility procedure based on the stored information, and Optionally, the circuit uses the determined configuration information of the SCG.

17. The UE according to claim 1, wherein: at least one cell configuration for the corresponding candidate target cell includes a cell pre-configuration for another candidate target cell, Upon successful completion of the conditional cell mobility procedure, the circuit: storing the cell pre-configuration for the another candidate target cell as the cell configuration for the another candidate target cell, · releasing the received multiple cell configuration, and • evaluating said execution condition of the stored cell configuration for said further candidate target cell.

18. A base station, comprising: circuitry that generates a plurality of cell configurations for a plurality of candidate target cells, wherein each cell configuration includes cell configuration parameters and execution conditions for a conditional cell mobility procedure, The multiple cell configurations include a first subset of cell configurations to be used when connecting to the base station, and a second subset of cell configurations to be used when connecting to a first candidate target cell among the multiple candidate target cells, A transmitter transmits the generated multiple cell configurations to the UE.

19. The base station according to claim 18, wherein: Generating the multiple cell configurations includes: The transmitter sends a request for requesting the cell configuration parameter of the first candidate target cell to the first candidate target cell, a receiver receiving, from the first candidate target cell, the cell configuration of at least another candidate target cell in response to the request, wherein the cell configuration of the another candidate target cell includes cell configuration parameters of the another candidate target cell to be used by the UE when connected to the first candidate target cell, and includes the execution condition regarding when to perform the conditional cell mobility procedure between the UE and the another candidate target cell when connected to the first candidate target cell, Optionally, the receiver receives the requested cell configuration parameters of the first candidate target cell from the first candidate target cell, and the circuit determines, for the requested cell configuration parameters of the first candidate target cell, the execution condition on when to perform the conditional cell mobility procedure between the UE and the first candidate target cell, Optionally, the circuit generates the 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.

20. A base station, comprising: a receiver receiving, from a source base station, a request for a cell configuration parameter of said base station for requesting a conditional cell mobility procedure, a circuit, which generates, in response to receiving the request, a cell configuration of at least another candidate target cell, wherein the cell configuration of the another candidate target cell includes a cell configuration parameter of the another candidate target cell and an execution condition of the conditional cell mobility, A transmitter transmits the generated cell configuration for the at least another candidate target cell to the source base station.

21. The base station according to claim 20, wherein: Generating the cell configuration for the at least another candidate target cell comprises: The transmitter sends a request for a cell configuration parameter of the another candidate target cell to the another candidate target cell, The receiver receives the requested cell configuration parameter of the another candidate target cell from the another candidate target cell, The circuit determines an execution condition regarding when to perform a conditional mobility procedure between the UE and the another candidate target cell while connected to the base station.

22. A method comprising the following steps performed by a user equipment UE: receiving a plurality of cell configurations for a plurality of candidate target cells from a source base station, wherein each cell configuration comprises a cell configuration parameter and an execution condition of a conditional cell mobility procedure, in, The plurality of cell configurations include 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 execution conditions of a first subset of the cell configurations, When the evaluated execution condition of the first subset of the cell configurations is satisfied for the first candidate target cell, a conditional cell mobility procedure with the first candidate target cell is performed based on the cell configuration parameters of the first candidate target cell.

23. A method comprising the following steps performed by a base station: generating a plurality of cell configurations for a plurality of candidate target cells, wherein each cell configuration comprises cell configuration parameters and execution conditions of a conditional cell mobility procedure, in, The plurality of cell configurations include 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, The generated multiple cell configurations are sent to the UE.

24. An integrated circuit controlling a process of a user equipment UE, the process comprising the following steps performed by the UE: receiving a plurality of cell configurations for a plurality of candidate target cells from a source base station, wherein each cell configuration comprises a cell configuration parameter and an execution condition of a conditional cell mobility procedure, in, The plurality of cell configurations include 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 execution conditions of a first subset of the cell configurations, When the evaluated execution condition of the first subset of the cell configurations is satisfied for the first candidate target cell, a conditional cell mobility procedure with the first candidate target cell is performed based on the cell configuration parameters of the first candidate target cell.

25. An integrated circuit controlling a process of a base station, the process comprising the following steps performed by the base station: generating a plurality of cell configurations for a plurality of candidate target cells, wherein each cell configuration comprises cell configuration parameters and execution conditions of a conditional cell mobility procedure, in, The plurality of cell configurations include 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, The generated multiple cell configurations are sent to the UE.

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