A method and device for conditional complete configuration and conditional incremental configuration

Abstract

A user equipment capable of receiving a full configuration associated with a radio connection to a base station and an incremental configuration that the user equipment can apply to a previously received first configuration, which (i) receives a full configuration from the base station while the user equipment is operating in a cell covered by the base station using the first configuration, the full configuration providing information for user equipment operation in a candidate cell (1404), (ii) determines whether a set of one or more conditions associated with the full configuration for the candidate cell are satisfied (1406), and (iii) if the user equipment determines that the set of conditions are satisfied, connects to the candidate cell using the full configuration (1410).

Description

Technical Field

[0001] The present disclosure relates generally to wireless communications, and more particularly to conditional operations related to conditional handover and conditional PSCell change with or without SN change. Conditional PSCell change with SN change may be referred to as conditional SN change. Background Art

[0002] The purpose of providing this background description is to generally present the context of the present disclosure. To the extent described in this background section, the work of the presently named inventors, as well as aspects of the description that may not be considered prior art at the time of filing, are neither explicitly nor implicitly admitted to be prior art against the present disclosure.

[0003] In telecommunication systems, the Packet Data Convergence Protocol (PDCP) sublayer of the radio protocol stack provides services such as user plane data transmission, encryption, integrity protection, etc. For example, the PDCP layer defined for the Evolved Universal Terrestrial Radio Access (EUTRA) radio interface (see 3GPP TS 36.323) and New Radio (NR) (see TS 38.323) provides sequencing of protocol data units (PDUs) in the uplink direction (from user equipment (UE) to base station) and in the downlink direction (from base station to UE). In addition, the PDCP sublayer provides signaling radio bearers (SRBs) and data radio bearers (DRBs) to the radio resource control (RRC) sublayer. In general, the UE and the base station can use SRBs to exchange RRC messages and non-access stratum (NAS) messages, and use DRBs to transmit data on the user plane.

[0004] There are several types of SRBs and DRBs that a UE can use. When operating in dual connectivity (DC), cells associated with a base station operating a primary node (MN) define a primary cell group (MCG), and cells associated with a base station operating as a secondary node (SN) define a secondary cell group (SCG). The so-called SRB1 resources carry RRC messages, which in some cases include non-access stratum (NAS) messages on a dedicated control channel (DCCH), and SRB2 resources support RRC messages including logged measurement information or NAS messages, also on the DCCH but with a lower priority than the SRB1 resources. More generally, SRB1 resources and SRB2 resources allow the UE and MN to exchange RRC messages related to the MN and embed RRC messages related to the SN, and may also be referred to as MCG SRBs. SRB3 resources allow the UE and SN to exchange RRC messages related to the SN, and may be referred to as SCG SRBs. Split SRBs allow the UE to exchange RRC messages directly with the MN via the lower layer resources of the MN and the SN. In addition, a DRB terminated at an MN and using only the lower layer resources of the MN may be referred to as an MCG DRB, a DRB terminated at an SN and using only the lower layer resources of the SN may be referred to as an SCG DRB, and a DRB terminated at an MCG but using the lower layer resources of the MN or the SN or both may be referred to as a split DRB.

[0005] In some cases, the UE can concurrently utilize the resources of multiple RAN nodes (e.g., components of a base station or a distributed base station) interconnected by a backhaul. When these network nodes support different radio access technologies (RATs), this type of connection is called multi-radio dual connection (MR-DC). When the UE operates in MR-DC, one base station operates as a master node (MN) covering a primary cell (PCell), and the other base station operates as a secondary node (SN) covering a primary secondary cell (PSCell). The UE communicates with the MN (via the PCell) and the SN (via the PSCell). In other cases, the UE utilizes the resources of one base station at a time. A base station and / or the UE determines that the UE should establish a radio connection with another base station. For example, a base station may determine to hand over the UE to a second base station and initiate a handover procedure.

[0006] 3GPP specification TS 37.340 (v15.7.0) describes procedures for adding or changing SNs in DC scenarios. These procedures involve messaging between RAN nodes (e.g., RRC signaling and preparation), which typically causes latency, which in turn increases the probability of failure of the SN addition or SN change procedures. These procedures do not involve conditions associated with the UE and can be referred to as "immediate" SN addition and change procedures. R2-1912344 describes procedures for conditionally adding or changing SNs in DC scenarios.

[0007] Recently, "conditional" procedures (i.e., conditional SN addition / change and conditional handover) have been considered for both SN addition / change and handover. Unlike the "immediate" procedures discussed above, these procedures do not add or change SNs, or perform handover, until the UE determines that a condition is met. As used herein, the term "condition" may refer to a single detectable state or event (e.g., a particular signal quality indicator exceeds a threshold), or a logical combination of these states or events (e.g., "condition A and condition B", or "(condition A or condition B) and condition C", etc.).

[0008] To configure the conditional procedure, the RAN provides the UE with conditions and configurations (e.g., a set of random access preambles, etc.) that, when the conditions are met, will enable the UE to communicate with an appropriate base station or via an appropriate cell. For example, for conditional addition of a base station as a SN, the RAN provides the UE with conditions to be met before the UE can add the base station as a SN, and configurations that enable the UE to communicate with the base station after the conditions have been met.

[0009] In a DC scenario, the UE receives an RRC reconfiguration message (e.g., RRCReconfiguration, RRCConnectionReconfiguration) containing an SCG configuration for the UE to communicate with the SN while the UE is connected to the MN. The SCG configuration ("baseline SCG configuration") is a baseline for future incremental configurations of a conditional PSCell change (i.e., from a PSCell currently used by the UE to communicate with the SN to a candidate PSCell (C-PSCell) of the SN (or another SN)) or a conditional PSCell addition (i.e., adding a C-PSCell of the SN (or another SN) in addition to the PSCell currently used by the UE to communicate with the SN). When the UE is in DC with the MN and the SN, the SN (or another SN) may generate at least one conditional SCG configuration and send the conditional SCG configuration to the UE. Upon receiving the conditional SCG configuration, if the user equipment determines that the condition(s) associated with the conditional SCG configuration are met, the UE configures or reconfigures (i.e., (re)configures) the baseline SCG configuration. According to 3GPP specification TS 38.331, the SN uses an incremental configuration rather than a full configuration as a conditional SCG configuration to (re)configure the SCG configuration for a conditional PSCell change or addition. When the SN uses an incremental configuration as a conditional SCG configuration for a conditional PSCell change or conditional PSCell addition, the SN parses the baseline SCG configuration that the UE currently uses to communicate with the SN to identify which configuration parameters to retain in the baseline SCG configuration, so that the SN can exclude shared (non-incremental) configuration parameters when generating an incremental configuration and subsequently providing the incremental configuration to the UE (e.g., via SRB3). This may result in inefficient use of resources when implementing a conditional PSCell change or addition. If the SN updates the baseline SCG configuration of the UE by sending an incremental SN configuration to the UE, the SN may thereby expend resources again to update the conditional SCG configuration previously provided to the UE, and transmit the updated conditional SCG configuration to the UE to update the conditional SCG configuration stored in the UE.

[0010] In addition, if the UE detects a radio link failure (RLF) on the PSCell, the UE attempts to connect to the SN (or another SN) via the C-PSCell. If the UE cannot connect via the C-PSCell, the UE performs a re-establishment procedure with the MN. However, according to Section 5.3.7 of 3GPP TS 36.331 / 38.331v15.7.0, if the UE performs a re-establishment procedure, the UE suspends all RBs except SRB0. Therefore, in the DC scenario, the UE cannot participate in future procedures for conditionally adding or changing SNs because the UE cannot receive future conditional SCG configurations from the SN (e.g., via SRB3).

[0011] 3GPP specifications 36.300 v15.7.0 and 38.300 v15.7.0 describe a handover procedure that includes several steps (RRC signaling and preparation) between RAN nodes, which results in delays in the handover procedure and, therefore, a higher risk of handover failure. The procedure does not involve conditions associated with the UE and may be referred to as an "immediate" handover procedure.

[0012] In a conditional handover scenario, while the UE is connected to the MN via a PCell with a single connection (SC), the UE receives an RRC configuration to communicate with the MN. This RRC configuration ("baseline RRC configuration") is a baseline for future incremental configurations for conditional handovers (i.e., from the PCell that the UE currently uses to communicate with the MN to the candidate PCell (C-PCell) of the candidate MN (C-MN)). In conditional handover within a base station, the MN generates a conditional handover command configuration. In conditional handover between base stations, the C-MN generates a conditional handover configuration and transmits the conditional handover configuration to the MN during the conditional handover procedure. After receiving the conditional handover configuration, if the user equipment determines that the (multiple) conditions associated with the conditional handover configuration are met, the UE (re)configures the baseline RRC configuration. When the MN or C-MN uses the incremental configuration as the conditional handover configuration, the MN or C-MN parses the baseline RRC configuration that the UE currently uses to communicate with the first base station to identify which configuration parameters to retain in the baseline RRC configuration, so that the MN or C-MN can exclude those shared (non-incremental) configuration parameters when generating the incremental configuration and subsequently providing the incremental configuration to the UE. This may result in inefficient use of resources when implementing conditional handover. If the MN or C-MN updates and provides the baseline RRC configuration to the UE, the MN or C-MN may again expend resources to thereby update the incremental configuration previously provided to the UE (as well as any other (multiple) incremental configurations), and transmit the updated incremental configuration to the UE. Summary of the invention

[0013] According to some techniques of the present disclosure, while the user equipment is operating in a cell covered by the base station using a previously received configuration, the base station determines to configure a complete configuration for the user equipment. The base station then identifies at least a candidate cell for the complete configuration. Subsequently, the base station sends the complete configuration to the user equipment and an indication of a set of one or more conditions to be satisfied before the user equipment communicates with the base station via the candidate cell using the complete configuration.

[0014] According to other technologies of the present disclosure, the base station sends a second configuration to the user equipment so that the user equipment updates the previously received first configuration according to the second configuration. Then, while the user equipment is operating in a cell covered by the base station using the first configuration, the base station determines to configure an incremental configuration for the user equipment, wherein the incremental configuration includes an indication that the UE is to modify the second configuration. The base station then identifies at least a candidate cell for the incremental configuration, and then sends the incremental configuration to the user equipment and an indication of a set of one or more conditions to be met before the user equipment communicates with the base station via the candidate cell using the incremental configuration. When the user equipment determines that the set of one or more conditions is met, the incremental configuration and the indication of the set of one or more conditions are sent so that the user equipment communicates with the base station using the incremental configuration and at least a portion of the second configuration.

[0015] According to other techniques of the present disclosure, while the user equipment is operating in a cell covered by the base station using a previously received first configuration, the user equipment receives a complete configuration from the base station, the complete configuration providing information for the user equipment operation in the candidate cell. The user equipment then determines whether a set of one or more conditions associated with the complete configuration of the candidate cell is satisfied. Subsequently, if the user equipment determines that the set of conditions is satisfied, the UE uses the complete configuration to connect to the candidate cell.

[0016] According to other technologies of the present disclosure, while the user equipment is operating in a cell covered by a base station using a previously received first configuration, the user equipment receives a second configuration from the base station, the second configuration being used to update the first configuration for operating in the cell covered by the base station. While the user equipment is operating in the cell, the user equipment receives a first incremental configuration from the base station, the first incremental configuration providing information for the operation of the user equipment in the first candidate cell, wherein the first incremental configuration includes an indication for modifying the second configuration. The user equipment then determines whether a set of one or more conditions associated with the first incremental configuration of the first candidate cell is satisfied. Before detecting that a set of one or more conditions associated with the first incremental configuration of the first candidate cell is satisfied, the user equipment updates the first configuration according to the second configuration, and communicates with the base station using the updated configuration. After detecting that a first set of one or more conditions associated with the first incremental configuration of the first candidate cell is satisfied, the user equipment uses the first incremental configuration and at least a portion of the updated first configuration or one of at least a portion of the first configuration to connect to the first candidate cell.

[0017] According to other technologies of the present disclosure, while the user equipment is operating in a cell covered by a base station using a previously received configuration, the user equipment receives a first incremental configuration from the base station, the first incremental configuration providing information for the operation of the user equipment in a first candidate cell. While the user equipment is operating in a cell covered by the base station using the previously received configuration, the user equipment also receives a second incremental configuration from the base station, the second incremental configuration providing information for the operation of the user equipment in a second candidate cell. The user equipment detects that a second set of one or more conditions associated with the second incremental configuration for connecting to the second candidate cell is satisfied. Subsequently, the user equipment connects to the second candidate cell using the second incremental configuration and a portion of the previously received configuration. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1A is a block diagram of an example system in which a radio access network (RAN) and user equipment may implement the techniques of the present disclosure for managing conditional procedures associated with a secondary node (SN);

[0019] Figure 1B The centralized unit (CU) and the distributed unit (DU) can be Figure 1A A block diagram of an example base station operating in a system of FIG.

[0020] FIG2 is a block diagram of an example protocol stack. Figure 1A The UE communicates with the base station according to the example protocol stack;

[0021] Figure 3Ais a message passing diagram of an example scenario according to the technology of the present disclosure, in which, Figure 1A or Figure 1B SN via Figure 1A or Figure 1B The MN initiates the conditional PSCell change procedure using a complete configuration including a complete configuration indication;

[0022] Figure 3B is a message passing diagram of an example scenario according to the technology of the present disclosure, in which, Figure 1A or Figure 1B SN via Figure 1A or Figure 1B The MN initiates the conditional PSCell change procedure using the complete configuration and complete configuration indication;

[0023] Figure 4 is a message passing diagram of an example scenario according to the technology of the present disclosure, in which, Figure 1A or Figure 1B The SN initiates the conditional PSCell change procedure using a complete configuration including a complete configuration indication;

[0024] Figure 5A is a message passing diagram of an example scenario according to the technology of the present disclosure, in which, Figure 1A or Figure 1B The MN initiates the conditional SN change procedure using a complete configuration including a complete configuration indication;

[0025] Figure 5B is a message passing diagram of an example scenario according to the technology of the present disclosure, in which, Figure 1A or Figure 1B The MN initiates a conditional SN change procedure via a request to the C-SN using a complete configuration including a complete configuration indication;

[0026] Fig. 6A is a message passing diagram of an example scenario according to the technology of the present disclosure, in which, Figure 1A or Figure 1B SN via Figure 1A or Figure 1B The MN uses incremental configuration to initiate the conditional PSCell change procedure;

[0027] Figure 6B is a message passing diagram of an example scenario according to the technology of the present disclosure, in which, Figure 1A or Figure 1B The SN uses incremental configuration to initiate the conditional PSCell change procedure;

[0028] Fig. 7Ais a message passing diagram of an example scenario according to the technology of the present disclosure, in which, Figure 1A or Figure 1B The SN uses incremental configuration to initiate a conditional PSCell change procedure and Figure 1A or Figure 1B The MN provides a configuration for updating a configuration previously received at the UE;

[0029] Figure 7B is a message passing diagram of an example scenario according to the technology of the present disclosure, in which, Figure 1A or Figure 1B The SN initiates a conditional PSCell change procedure using incremental configuration and provides a configuration for updating the configuration previously received at the UE;

[0030] Fig. 8A is a message passing diagram of an example scenario according to the technology of the present disclosure, in which, Figure 1A or Figure 1B SN via Figure 1A or Figure 1B The MN initiates a conditional PSCell change procedure using the first incremental configuration and the second incremental configuration;

[0031] Figure 8B is a message passing diagram of an example scenario according to the technology of the present disclosure, in which, Figure 1A or Figure 1B The SN initiates a conditional PSCell change procedure using the first incremental configuration and the second incremental configuration;

[0032] Fig. 9A is a message passing diagram of an example scenario according to the technology of the present disclosure, in which, Figure 1A or Figure 1B The MN initiates the conditional handover procedure using the complete configuration via a request to the C-MN;

[0033] Fig. 9B is a message passing diagram of an example scenario according to the technology of the present disclosure, in which, Figure 1A or Figure 1B The MN initiates a conditional handover procedure using incremental configuration via a request to the C-MN;

[0034] Fig. 10A is a message passing diagram of an example scenario according to the technology of the present disclosure, in which, Figure 1A or Figure 1B The MN initiates the conditional handover procedure using the complete configuration;

[0035] Fig. 10Bis a message passing diagram of an example scenario according to the technology of the present disclosure, in which, Figure 1A or Figure 1B The MN uses incremental configuration to initiate the conditional handover procedure;

[0036] Fig.11A is a message passing diagram of an example scenario according to the technology of the present disclosure, in which, before the UE detects a failure in the connection with the PSCell, Figure 1A or Figure 1B The SN initiates the conditional PSCell change procedure;

[0037] Fig. 11B is a message passing diagram of an example scenario according to the technology of the present disclosure, in which, before the UE detects a failure in the connection with the PSCell, Figure 1A or Figure 1B The MN initiates the conditional SN change procedure;

[0038] Fig.12 is a flow chart of an example method for initiating a conditional PSCell change procedure according to the techniques of the present disclosure, which may be performed in Figure 1A or Figure 1B Implementation in SN;

[0039] Fig.13A is a flow chart of an example method for initiating a conditional PSCell change procedure according to the techniques of the present disclosure, which may be performed in Figure 1A or Figure 1B Implementation in MN;

[0040] Fig. 13B is a flowchart of another example method for initiating a conditional PSCell change procedure according to the techniques of the present disclosure, which may be performed in Figure 1A or Figure 1B Implementation in MN;

[0041] Fig.14 is a flow chart of an example method for initiating a conditional PSCell change procedure according to the techniques of the present disclosure, which may be performed in Figure 1A or Figure 1B Implementation in UE;

[0042] Fig.15 is a flowchart of another example method for initiating a conditional PSCell change procedure according to the techniques of the present disclosure, which may be performed in Figure 1A or Figure 1B Implementation in SN;

[0043] Fig.16is a flow chart of an example method for initiating a conditional PSCell change procedure according to the techniques of the present disclosure, which may be performed in Figure 1A or Figure 1B Implementation in UE;

[0044] Fig.17 is a flowchart of another example method for initiating a conditional PSCell change procedure according to the techniques of the present disclosure, which may be performed in Figure 1A or Figure 1B Implementation in SN;

[0045] Fig.18 is a flow chart of an example method for initiating a conditional PSCell change procedure according to the techniques of the present disclosure, which may be performed in Figure 1A or Figure 1B Implementation in UE;

[0046] Fig.19 is a flow chart of an example method for initiating a conditional PSCell change procedure before a UE detects a failure in connection with a PSCell according to the techniques of this disclosure; and

[0047] Fig. 20 is a flow chart of an example method for performing an immediate PCell change, an immediate PSCell change, or a conditional PSCell change in accordance with the techniques of this disclosure. DETAILED DESCRIPTION

[0048] Generally speaking, the communication devices of the present disclosure implement procedures related to conditional handover, conditional primary secondary cell (PSCell) addition, and conditional PSCell change configured with or without SN change.

[0049] Figure 1A An example wireless communication system 100 is depicted in which a communication device may implement these techniques. The wireless communication system 100 includes a UE 102, a base station 104, a base station 106A, a base station 106B, and a core network (CN) 110. The UE 102 initially connects to the base station 104.

[0050] In some scenarios, base station 104 may perform an immediate SN addition to configure UE 102 to operate in dual connectivity (DC) with base station 104 (via PCell) and base station 106A (via a PSCell different from cell 126A). Base stations 104 and 106A operate as the MN and SN of UE 102, respectively. Later, in one scenario, while UE 102 is in DC with MN 104 and S-SN 106A, MN 104 may perform an immediate SN change to change the SN of UE 102 from base station 106A (source SN or “S-SN”) to base station 106B (target SN or “T-SN”). In another scenario, SN 106A may perform an immediate PSCell change to change the PSCell of UE 102 to cell 126A. In one embodiment, SN 106A may send a configuration to change the PSCell to cell 126A to UE 102 via a signaling radio bearer (SRB) (e.g., SRB3) for an immediate PSCell change. In another embodiment, SN 106A may send a configuration to change the PSCell to cell 126A to UE 102 via MN 104 for an immediate PSCell change. MN 104 may send a configuration to change the PSCell to cell 126A to UE 102 via SRB1 for an immediate PSCell change.

[0051] In other scenarios, the base station 104 may perform a conditional SN addition procedure to first configure the base station 106A as a candidate SN (C-SN) for the UE 102. At this time, the UE 102 may be in a single connection (SC) with the base station 104, or in a DC with the base station 104 and another base station 106B. If the UE 102 is in a DC with the base station 104 and the base station 106B, the MN 104 may determine to perform the conditional SN addition procedure in response to a request received from the base station 106B, or in response to one or more measurement results received from the UE 102 or obtained by the MN 104 from measurements of signals received from the UE 102. In contrast to the case of immediately adding a SN discussed above, the UE 102 does not immediately attempt to connect to the C-SN 106A. In this scenario, the base station 104 operates as a MN again, but the base station 106A initially operates as a C-SN instead of an SN.

[0052] More specifically, when UE 102 receives the configuration for C-SN 106A, UE 102 does not connect to C-SN 106A until UE 102 has determined that a certain condition is satisfied (in some cases, UE 102 may consider multiple conditions, but for convenience, the following discussion only relates to a single condition). When UE 102 determines that the condition has been satisfied, UE 102 connects to C-SN 106A, causing C-SN 106A to begin operating as SN 106A for UE 102. Thus, although base station 106A operates as a C-SN instead of an SN, base station 106A is not yet connected to UE 102, and accordingly is not yet serving UE 102. In some implementations, UE 102 may disconnect from SN 106B to connect to C-SN 106A.

[0053] In yet another scenario, UE 102 is in communication with MN 104 (via PCell) and SN 106A (via a cell other than cell 126A and not in Figure 1A SN 106A may configure C-PSCell 126A for UE 102. If UE 102 is configured with a signaling radio bearer (SRB) (e.g., SRB3) to exchange RRC messages with SN 106A, SN 106A may send a configuration for C-PSCell 126A to UE 102 via SRB (e.g., in response to one or more measurement results that may be received from UE 102 via SRB or via MN 104 or may be obtained by SN 106A from measurements of signals received from UE 102). In the case of via MN 104, MN 104 receives the configuration of C-PSCell 126A. In contrast to the case of immediate PSCell change discussed above, UE 102 does not immediately disconnect from the PSCell and attempts to connect to C-PSCell 126A.

[0054] More specifically, when UE 102 receives the configuration for C-PSCell 126A, UE 102 does not connect to C-PSCell 126A until UE 102 has determined that a certain condition is satisfied (in some cases, UE 102 may consider multiple conditions, but for convenience, the following discussion only relates to a single condition). When UE 102 determines that the condition has been satisfied, UE 102 connects to C-PSCell 126A so that C-PSCell 126A begins to operate as PSCell 126A for UE 102. Therefore, although cell 126A operates as a C-PSCell rather than a PSCell, SN 106A may not yet be connected to UE 102 via cell 126A. In some implementations, UE 102 may disconnect from the PSCell to connect to C-PSCell 126A.

[0055] In some scenarios, the condition associated with conditional SN addition or conditional PSCell change may be that the signal strength / quality detected by the UE 102 on the C-PSCell of the (C-)SN 106A exceeds a certain threshold or otherwise corresponds to an acceptable measurement. For example, when one or more measurement results obtained by the UE 102 on the C-PSCell 126A are higher than a threshold configured by the MN 104 or the (C-)SN 106A or higher than a predetermined or preconfigured threshold, the UE 102 determines that the condition is satisfied. When the UE 102 determines that the signal strength / quality on the C-PSCell of the (C-)SN 106A is good enough (again, measured relative to one or more quantitative thresholds or other quantitative indicators), the UE 102 may perform a random access procedure on the C-PSCell 126A with the (C-)SN 106A to connect to the (C-)SN 106A. Once the UE 102 successfully completes the random access procedure on the C-PSCell 126A, the C-PSCell 126A becomes the PSCell 126A for the UE 102. The (C-)SN 106A may then begin communicating data (user plane data or control plane data) with the UE 102 over the PSCell 126A.

[0056] In various configurations of the wireless communication system 100, the base station 104 may be implemented as a master eNB (MeNB) or a master gNB (MgNB), and the base station 106A or 106B may be implemented as a secondary gNB (SgNB) or a candidate SgNB (C-SgNB). The UE 102 may communicate with the base station 104 and the base station 106A or 106B (106A / B) via the same RAT (such as EUTRA or NR) or different RATs. When the base station 104 is a MeNB and the base station 106A is an SgNB, the UE 102 may be in EUTRA-NRDC (EN-DC) with the MeNB and the SgNB. In this scenario, the MeNB 104 may or may not configure the base station 106B as a C-SgNB for the UE 102. In this scenario, the SgNB 106A may configure the cell 126A as a C-PSCell for the UE 102. When base station 104 is a MeNB and base station 106A is a C-SgNB of UE 102, UE 102 may be in SC with the MeNB. In this scenario, MeNB 104 may or may not configure base station 106B as another C-SgNB for UE 102.

[0057] In some cases, the MeNB, SeNB, or C-SgNB is implemented as an ng-eNB instead of an eNB. When the base station 104 is a master ng-eNB (Mng-eNB) and the base station 106A is an SgNB, the UE 102 may be in a next generation (NG) EUTRA-NR DC (NGEN-DC) with the Mng-eNB and the SgNB. In this scenario, the MeNB 104 may or may not configure the base station 106B as the C-SgNB of the UE 102. In this scenario, the SgNB 106A may configure the cell 126A as the C-PSCell of the UE 102. When the base station 104 is a Mng-NB and the base station 106A is the C-SgNB of the UE 102, the UE 102 may be in a SC with the Mng-NB. In this scenario, the Mng-eNB 104 may or may not configure the base station 106B as another C-SgNB of the UE 102.

[0058] When the base station 104 is a MgNB and the base station 106A / B is an SgNB, the UE 102 may be in NR-NR DC (NR-DC) with the MgNB and the SgNB. In this scenario, the MeNB 104 may or may not configure the base station 106B as a C-SgNB for the UE 102. In this scenario, the SgNB 106A may configure the cell 126A as a C-PSCell for the UE 102. When the base station 104 is a MgNB and the base station 106A is a C-SgNB for the UE 102, the UE 102 may be in SC with the MgNB. In this scenario, the MgNB 104 may or may not configure the base station 106B as another C-SgNB for the UE 102.

[0059] When the base station 104 is a MgNB and the base station 106A / B is a secondary ng-eNB (Sng-eNB), the UE 102 may be in NR-EUTRA DC (NE-DC) with the MgNB and the Sng-eNB. In this scenario, the MgNB 104 may or may not configure the base station 106B as a C-Sng-eNB for the UE 102. In this scenario, the Sng-eNB 106A may configure the cell 126A as a C-PSCell for the UE 102. When the base station 104 is a MgNB and the base station 106A is a candidate Sng-eNB (C-Sng-eNB) for the UE 102, the UE 102 may be in SC with the MgNB. In this scenario, the MgNB 104 may or may not configure the base station 106B as another C-Sng-eNB for the UE 102.

[0060] The base stations 104, 106A, and 106B may be connected to the same core network (CN) 110, which may be an evolved packet core (EPC) 111 or a fifth generation core (5GC) 160. The base station 104 may be implemented as an eNB supporting an S1 interface for communicating with the EPC 111, an ng-eNB supporting an NG interface for communicating with the 5GC 160, or a base station supporting an NR radio interface and an NG interface for communicating with the 5GC 160. The base station 106A may be implemented as an EN-DC gNB (en-gNB) having an S1 interface to the EPC 111, an en-gNB not connected to the EPC 111, a gNB supporting an NR radio interface and an NG interface to the 5GC 160, or an ng-eNB supporting an EUTRA radio interface and an NG interface to the 5GC 160. To directly exchange messages during the scenarios discussed below, base stations 104, 106A, and 106B may support an X2 or Xn interface.

[0061] Among other components, the EPC 111 may include a serving gateway (S-GW) 112 and a mobility management entity (MME) 114. The S-GW 112 is typically configured to deliver user plane packets associated with audio calls, video calls, Internet traffic, etc., and the MME 114 is configured to manage authentication, registration, paging, and other related functions. The 5GC 160 includes a user plane function (UPF) 162 and an access and mobility management (AMF) 164 and / or a session management function (SMF) 166. Generally speaking, the UPF 162 is configured to deliver user plane packets associated with audio calls, video calls, Internet traffic, etc., the AMF 164 is configured to manage authentication, registration, paging, and other related functions, and the SMF 166 is configured to manage PDU sessions.

[0062] like Figure 1A As shown, base station 104 supports cell 124, base station 106A supports cell 126A, and base station 106B supports cell 126B. Cells 124 and 126A may partially overlap, as may cells 124 and 126B, such that UE 102 may communicate with base station 104 (operating as a MN) and base station 106A (operating as a SN) in DC, and after completing the SN change, communicate with base station 104 (operating as a MN) and SN 106B. More specifically, when UE 102 is in DC with base station 104 and base station 106A, base station 104 operates as a MeNB, Mng-eNB, or MgNB, and base station 106A operates as an SgNB or Sng-eNB. When UE 102 is in SC with base station 104, base station 104 operates as a MeNB, Mng-eNB, or MgNB, and base station 106A operates as a C-SgNB or C-Sng-eNB.

[0063] In general, the wireless communication network 100 may include any suitable number of base stations supporting NR cells and / or EUTRA cells. More specifically, the EPC 111 or 5GC 160 may be connected to any suitable number of base stations supporting NR cells and / or EUTRA cells. Although the following examples specifically relate to specific CN types (EPC, 5GC) and RAT types (5G NR and EUTRA), the techniques of the present disclosure may also be applied to other suitable radio access and / or core network technologies, such as sixth generation (6G) radio access and / or 6G core network or 5G NR-6G DC.

[0064] Continue to refer Figure 1AThe base station 104 is equipped with processing hardware 130, which may include one or more general-purpose processors (such as CPUs) and non-transitory computer-readable memory storing machine-readable instructions that can be executed on one or more general-purpose processors and / or special-purpose processing units. The processing hardware 130 in the example embodiment includes a MN RRC controller 132 configured to manage or control one or more RRC configurations or RRC procedures when the base station 104 operates as a MN.

[0065] The base station 106A is equipped with processing hardware 140, which may also include one or more general-purpose processors (such as CPUs) and non-transitory computer-readable memory storing machine-readable instructions that can be executed on one or more general-purpose processors and / or special-purpose processing units. The processing hardware 140 in the example embodiment includes a (C-)SN RRC controller 142 configured to manage or control one or more RRC configurations and / or RRC procedures when the base station 106A operates as a SN or a candidate SN (C-SN). The base station 106B may have the same or similar hardware as the base station 106A.

[0066] although Figure 1A RRC controllers 132 and 142 are shown as operating in MN and SN, respectively, but in different scenarios, a base station can generally operate as a MN, SN, or candidate SN. Therefore, MN 104, SN 106A, and SN 106B can implement a similar set of functions and support MN, SN, and conditional SN operations.

[0067] Still reference Figure 1A , UE 102 is equipped with processing hardware 150, which may include one or more general-purpose processors (such as CPUs) and non-transitory computer-readable memory storing machine-readable instructions that can be executed on one or more general-purpose processors and / or special-purpose processing units. The processing hardware 150 in the example embodiment includes a UE RRC controller 152 configured to manage or control one or more RRC configurations and / or RRC procedures.

[0068] In operation, UE 102 may use radio bearers (e.g., DRBs or SRBs) that terminate at different times at MN 104 or SN 106A. UE 102 may apply one or more security keys when communicating on the radio bearers in the uplink (from UE 102 to the base station) and / or downlink (from the base station to UE 102) directions.

[0069] Figure 1BAn example distributed implementation of a base station, such as base station 104, 106A, or 106B, is depicted. The base station in this implementation may include a centralized unit (CU) 172 and one or more distributed units (DUs) 174. CU 172 is equipped with processing hardware, which may include one or more general-purpose processors (such as CPUs) and non-transitory computer-readable memory storing machine-readable instructions that can be executed on one or more general-purpose processors and / or special-purpose processing units. In one example, CU 172 is equipped with processing hardware 130. In another example, CU 172 is equipped with processing hardware 140. The processing hardware 140 in the example implementation includes a (C-)SN RRC controller 142 configured to manage or control one or more RRC configurations and / or RRC procedures when base station 106A operates as an SN or a candidate SN (C-SN). Base station 106B may have the same or similar hardware as base station 106A. DU 174 is also equipped with processing hardware, which may include one or more general-purpose processors (such as CPUs) and non-transitory computer-readable memory storing machine-readable instructions that can be executed on one or more general-purpose processors and / or special-purpose processing units. In some examples, the processing hardware in the example implementation includes a media access control (MAC) controller configured to manage or control one or more MAC operations or procedures (e.g., random access procedures), and a radio link control (RLC) controller configured to manage or control one or more RLC operations or procedures when base station 106A operates as a MN, SN, or candidate SN (C-SN). The processing hardware may also include a physical layer controller configured to manage or control one or more physical layer operations or procedures.

[0070] 2 shows in a simplified manner a radio protocol stack according to which the UE 102 can communicate with an eNB / ng-eNB or a gNB. Each of the base stations 104, 106A, or 106B can be an eNB / ng-eNB or a gNB.

[0071] The physical layer (PHY) 202A of EUTRA provides transport channels to the EUTRA medium access control (MAC) sublayer 204A, which in turn provides logical channels to the EUTRA radio link control (RLC) sublayer 206A, and the EUTRA RLC sublayer in turn provides RLC channels to the EUTRA PDCP sublayer 208 and, in some cases, to the NR PDCP sublayer 210. Similarly, the PHY 202B of NR provides transport channels to the NR MAC sublayer 204B, which in turn provides logical channels to the NR RLC sublayer 206B, and the NR RLC sublayer 206B provides RLC channels to the NR PDCP sublayer 210. In some embodiments, the UE 102 supports both the EUTRA stack and the NR stack to support handover between a EUTRA base station and an NR base station and / or DC on the EUTRA interface and the NR interface. In addition, as shown in Figure 2A, the UE 102 can support the layering of NR PDCP 210 on the EUTRA RLC 206A.

[0072] The EUTRA PDCP sublayer 208 and the NR PDCP sublayer 210 receive packets, which may be referred to as service data units (SDUs) (e.g., from an Internet Protocol (IP) layer layered directly or indirectly on the PDCP layer 208 or 210), and output packets, which may be referred to as protocol data units (PDUs) (e.g., to the RLC layer 206A or 206B). For simplicity, this disclosure refers to both SDUs and PDUs as "packets" except where the difference between SDUs and PDUs is relevant.

[0073] On the control plane, the EUTRA PDCP sublayer 208 and the NR PDCP sublayer 210 provide SRBs to exchange, for example, radio resource control (RRC) messages. On the user plane, the EUTRA PDCP sublayer 208 and the NR PDCP sublayer 210 provide DRBs to support data exchange.

[0074] When UE 102 operates in EUTRA / NR DC (EN-DC), where BS 104 operates as a MeNB and BS 106A operates as an SgNB, the network can provide UE 102 with a MN terminated bearer using EUTRA PDCP 208 or a MN terminated bearer using NR PDCP 210. The network in various scenarios can also provide UE 102 with an SN terminated bearer using only NR PDCP 210. The MN terminated bearer can be an MCG bearer or a separated bearer. The SN terminated bearer can be an SCG bearer or a separated bearer. The MN terminated bearer can be an SRB (e.g., SRB1 or SRB2) or a DRB. The SN terminated bearer can be an SRB (e.g., SRB3) or a DRB.

[0075] Next, refer to Figure 3A-Figure 8B Several example scenarios are discussed in which a base station initiates a conditional PSCell change procedure.

[0076] First reference Figure 3A , the base station 104 in the scenario 300 operates as a MN, and the base station 106A operates as a SN. Initially, the UE 102 in DC with the MN 104 and the SN 106A communicates 302 UL data PDUs and / or DL ​​data PDUs with the MN 104 via the PCell, and communicates 302 UL data PDUs and / or DL ​​data PDUs with the SN 106A via the PSCell (i.e., a cell other than the cell 126A). The SN 106A determines 304 to configure a full C-SN configuration, which configures the C-PSCell 126A. The SN 106A may make this determination based on one or more measurements received from the UE 102 via the MN 104, one or more measurements received directly from the UE (e.g., via a signaling radio bearer (SRB) established between the UE 102 and the SN 106A or via a physical control channel), or one or more measurements obtained by the SN 106A from measurements of, for example, a signal, control channel, or data channel received from the UE 102, or another suitable event. In response to the determination, the SN 106A transmits 306 a complete C-SN configuration including a complete configuration indication to the MN 104, which then sends an RRC reconfiguration message including the complete C-SN configuration to the UE 102. In some implementations, the UE 102 may send 310 an RRC reconfiguration complete message to the MN 104 in response to the RRC reconfiguration message. The MN 104 may send 312 an SN reconfiguration complete message to the SN 106A in response to the RRC reconfiguration complete message.

[0077] The UE 102 detects 314 that a condition (or conditions) for connecting to the C-PSCell 126A is met, and initiates a random access procedure on the C-PSCell 126A in response to the detection. For convenience, the following discussion refers to a condition or configuration in the singular, but it will be understood that it can be one or more conditions, or include one or more configuration parameters. In response to the initiation, the UE 102 performs 316 a random access procedure with the SN 106A via the C-PSCell 126A using the random access configuration in the complete C-SN configuration. The UE 102 may disconnect from the PSCell in response to the initiation or detection. In some embodiments, the random access procedure may be a 4-step random access procedure or a 2-step random access procedure. In other embodiments, the random access procedure may be a contention-based random access procedure or a contention-free random access procedure. After the UE 102 successfully completes the random access procedure 316, the UE 102 in the DC with the MN 104 and the SN 106A communicates 318 with the SN 106A via the C-PSCell 126A (i.e., the new PSCell 126A) using the complete C-SN configuration. The UE 102 releases 320 the SN configuration in response to the complete configuration indication. If the SN 106A identifies the UE 102 in the random access procedure 316, the SN 106A may release 322 the SN configuration. In some implementations, the SN 106A identifies the UE 102 if the SN 106A finds the identity of the UE 102 in a media access control (MAC) protocol data unit (PDU) received from the UE 102 in the random access procedure 316. The SN 106A includes the identity of the UE 102 in the complete C-SN configuration. In other embodiments, if the SN 106A receives a dedicated random access preamble from the UE 102 in the random access procedure 316, the SN 106A identifies the UE 102. The SN 106A includes the dedicated random access preamble in the complete C-SN configuration.

[0078] A "full" C-SN configuration is a complete and independent configuration (i.e., a complete configuration). A full configuration indication (information element (IE)) indicates that a "full" C-SN configuration is a complete and independent configuration (i.e., a complete configuration). UE 102 may communicate with SN 106A using the full C-SN configuration directly according to the full configuration indication without referring to the SN configuration. The full C-SN configuration may include multiple configuration parameters for UE 102 to communicate with SN 106A via C-PSCell 126A. Multiple configuration parameters may configure radio resources for UE 102 to communicate with SN 106A via zero, one or more candidate secondary cells (C-SCells) of C-PSCell 126A and SN 106A. Multiple configuration parameters may configure zero, one or more radio bearers. One or more radio bearers may include SRBs and / or (multiple) data radio bearers (DRBs).

[0079] The SN configuration may include multiple configuration parameters for UE 102 to communicate with SN 106A via zero, one or more secondary cells (SCells) of the PSCell and SN 106A. The multiple configuration parameters may configure radio resources for UE 102 to communicate with SN 106A via zero, one or more SCells of the PSCell and SN 106A. The multiple configuration parameters may configure zero, one or more radio bearers. The one or more radio bearers may include SRBs and / or (multiple) DRBs.

[0080] In some embodiments, the SN 106A may include the complete C-SN configuration in an SN Add Modify Confirm message in response to the SN Modify Request message received from the MN 104, and transmit the SN Modify Request Confirm message to the MN 104 at event 306. In other embodiments, the SN 106A may include the complete C-SN configuration in an SN Modify Required message, and transmit the SN Modify Required message to the MN 104 at event 306. In some embodiments, the SN 106A may indicate that the SN Modify Request Confirm message or the SN Modify Required message is for a conditional PSCell change.

[0081] In some implementations, SN 106A includes a conditional configuration that configures the condition that UE 102 detected in the complete C-SN configuration at event 314. In other implementations, MN 104 may include the complete C-SN configuration and the conditional configuration that configures the condition in RRC reconfiguration message 308. MN 104 may generate the conditional configuration (e.g., at event 306) or receive the conditional configuration from SN 106A.

[0082] In some embodiments, the complete configuration indication may be a new field / IE newly defined in 3GPP TS 36.331 or 38.331. If the UE 102 detects that the conditions for connecting to the C-PSCell 126A are met, the new field / IE indicates that the UE 102 releases the SN configuration and directly uses the complete C-SN configuration. In other embodiments, the complete configuration indication may be an existing field / IE defined in 3GPP TS 36.331 or 38.331.

[0083] In some embodiments, the complete C-SN configuration may include configuring a group configuration (CellGroupConfig) IE of the C-PSCell 126A, and may configure zero, one, or more C-SCells of the SN 106A. In one embodiment, the complete C-SN configuration may be an RRCReconfiguration message, an RRCReconfiguration-IE, or a CellGroupConfigIE in accordance with 3GPP TS 38.331. The complete configuration indication may be a field or IE in accordance with 3GPP TS 38.331. In other embodiments, the complete C-SN configuration may include configuring an SCG-ConfigPartSCG-r12 IE of the C-PSCell 126A, and may configure zero, one, or more C-SCells of the SN 106A. In one embodiment, the complete C-SN configuration may be an RRCConnectionReconfiguration message, an RRCConnectionReconfiguration-IE, or a ConfigPartSCG-r12 IE in accordance with 3GPP TS 36.331. The complete configuration indication may be a field or IE compliant with 3GPP TS 36.331.

[0084] In some embodiments, the SN configuration may include a CellGroupConfig IE that configures the PSCell, and may configure zero, one, or more SCells of the SN 106A. In one embodiment, the SN configuration may be an RRCReconfiguration message, an RRCReconfiguration-IE, or a CellGroupConfig IE that complies with 3GPP TS38.331. In other embodiments, the SN configuration may include an SCG-ConfigPartSCG-r12 IE that configures the PSCell, and may configure zero, one, or more SCells of the SN 106A. In one embodiment, the SN configuration may be an RRCConnectionReconfiguration message, an RRCConnectionReconfiguration-IE, or a ConfigPartSCG-r12 IE that complies with 3GPP TS 36.331.

[0085] In some cases, UE 102 may receive one or more conditions (discussed below in singular form for convenience) in an RRC reconfiguration message or a complete C-SN configuration at event 308. UE 102 may use the one or more conditions to determine whether to connect to C-PSCell 126A. If UE 102 determines that the conditions are met, UE 102 connects to C-PSCell 126A. If UE 102 does not determine that the conditions are met, UE 102 does not connect to C-PSCell 126A.

[0086] In some embodiments, as shown in FIG. 2 , the SN 106A may be composed of a CU 172 and one or more DUs 174. The DU 174 may generate a complete C-SN configuration or a portion of the complete C-SN configuration and transmit the complete C-SN configuration or a portion of the complete C-SN configuration to the CU 172. In the case where the DU 174 generates a portion of the complete C-SN configuration, the CU 172 may generate the remaining portion of the complete C-SN configuration. In one embodiment, the DU 174 may perform a random access procedure 316 with the UE 102 and identify the UE 102 in the random access procedure. In another embodiment, the DU 174 may perform a random access procedure 316 with the UE 102 and forward the identity of the UE 102 received in the MAC PDU in the random access procedure to the CU 172. The CU 172 identifies the UE 102 based on the identity of the UE 102. In response to the identification, the CU 172 and the DU 174 communicate with the UE 102 using the complete C-SN configuration.

[0087] If the SN 106A identifies the UE 102 on the C-PSCell 126A at event 316, the SN 106A begins to send (multiple) downlink control information (DCI) commands, (multiple) reference signals, or data on a (multiple) physical downlink control channel (PDCCH) to the UE 102 via the C-PSCell 126A and / or one or more C-SCells (if configured in the full C-SN configuration) according to some configuration parameters in the complete C-SN configuration. If the SN 106A identifies the UE 102 on the C-PSCell 126A at event 316, the SN 106A may receive (multiple) signals, (multiple) sounding reference signals, or data on a (multiple) physical uplink control channel (PUCCH) from the UE 102 via the C-PSCell 126A and / or one or more C-SCells (if configured in the full C-SN configuration) according to some configuration parameters in the complete C-SN configuration. The UE 102 receives (multiple) DCI commands, (multiple) reference signals, or data on (multiple) PDCCHs from the SN 106A via the C-PSCell 126A and / or one or more C-SCells (if configured in the complete C-SN configuration) according to some configuration parameters in the complete C-SN configuration. The UE 102 may send (multiple) signals, (multiple) sounding reference signals, or data on (multiple) PUCCHs to the SN 106A via the C-PSCell 126A and one or more C-SCells (if configured in the complete C-SN configuration) according to some configuration parameters in the complete C-SN configuration.

[0088] As described above, before C-PSCell 126A becomes suitable for UE 102, SN 106A pre-configures C-PSCell 126A to UE 102 at events 306 and 308. When C-PSCell 126A becomes suitable for UE 102 (i.e., UE 102 detects corresponding conditions), UE 102 performs a random access procedure with C-PSCell 126A to quickly change PSCell. In contrast to the immediate PSCell change procedure, the conditional PSCell change technique discussed in the present disclosure significantly reduces the latency associated with DC configuration.

[0089] If MN 104 is a gNB, the RRC reconfiguration message and the RRC reconfiguration completion message are RRCReconfiguration message and RRCConnectionReconfigurationComplete message, respectively. If MN 104 is an eNB or ng-eNB, the RRC reconfiguration message and the RRC reconfiguration completion message are RRCReconfiguration message and RRCConnectionReconfigurationComplete message, respectively.

[0090] Next, Figure 3B 106A is a scenario involving a conditional C-PSCell change without a SN change (i.e., a conditional change of the PSCell of the SN when the UE is already in DC with both the MN and the SN). In this scenario, BS 104 operates as a MN and BS 106A operates as a SN. Events 352, 354, 356, 358, 360, 362, 364, 366, 368, 370, and 372 in this scenario are similar to those described in reference 106A. Figure 3A Events 302, 304, 306, 308, 310, 312, 314, 316, 318, 320, and 322 are discussed below. Figure 3A and Figure 3B The difference between the scenes.

[0091] exist Figure 3B In the scenario 350 of FIG. 3 , SN 106A includes the complete C-SN configuration and the first complete configuration indication in an interface message (e.g., an SN modification request confirmation message or an SN modification required message as described above), instead of including the complete configuration indication in the complete C-SN configuration. That is, SN 106A does not include the complete configuration indication in the complete C-SN configuration. SN 106A transmits 356 the interface message to MN 104. Then MN 104 includes the second complete configuration indication in an RRC reconfiguration message in response to the first complete configuration indication, and includes the complete C-SN configuration in the RRC reconfiguration message. Then, MN 104 transmits 358 the RRC reconfiguration message to UE 102.

[0092] In some embodiments, the first complete configuration indication may be an IE included in the interface message. For example, the IE may comply with 3GPP TS 36.423 or 38.423. The second complete configuration indication may be an IE that complies with 3GPP TS 36.331 or 38.331. In some embodiments, the second complete configuration indication may be a new field / IE newly defined in 3GPP TS 36.331 or 38.331. If the UE 102 detects that the conditions for connecting to the C-PSCell 126A are met, the new field / IE indicates that the UE 102 releases the SN configuration and directly uses the complete C-SN configuration.

[0093] Go to Figure 4 , which shows a scenario involving a conditional C-PSCell change without an SN change (i.e., a conditional change of the PSCell of the SN when the UE is already in DC with both the MN and the SN). In this scenario, BS 104 operates as a MN and BS 106A operates as a SN. Events 402, 404, 414, 416, 418, 420, and 422 in this scenario are similar to those described in reference 4. Figure 3A Events 302, 304, 310, 312, 314, 316, 318, 320, and 322 are discussed below. Figure 3A and Figure 4 The difference between the scenes.

[0094] exist Figure 4In the scenario 400 of FIG. 4 , SN 106A directly sends 408 a complete C-SN configuration including a complete configuration indication to UE 102, instead of transmitting it to the UE via MN 104. In some embodiments, SN 106A configures a first SRB to UE 102 via MN 104, and sends the complete C-SN configuration to UE 102 via the first SRB. In response to receiving the complete configuration indication, if UE 102 detects that a condition for connecting to C-PSCell 126A is met, UE 102 may replace the SN configuration with the complete C-SN configuration. For example, SN 106A transmits an SRB configuration configuring a first SRB (e.g., SRB3) to MN 104, and MN 104 sends the SRB configuration to the UE via a second SRB (e.g., SRB1) between MN 104 and UE 102. If the complete C-SN configuration includes an SRB configuration and the UE 102 is connected to the C-PSCell 126A, the UE 102 may replace the SRB configuration in the SN configuration with the SRB configuration in the complete C-SN configuration. In another example, if the complete C-SN configuration includes a DRB configuration and the UE 102 is connected to the C-PSCell 126A, the UE 102 may replace the DRB configuration in the SN configuration with the DRB configuration in the complete C-SN configuration. In some implementations, the UE 102 may send an RRC reconfiguration complete message to the SN 106A via the first SRB in response to the complete C-SN configuration.

[0095] Next, Figure 5A Another scenario 500 involving conditional SN change is shown. In this scenario, BS 104 operates as a MN, BS 106A operates as a C-SN, and BS 106B operates as a SN. Some events in scenario 500 are similar to those in scenario 300. Figure 3A and Figure 5A The difference between the scenes.

[0096] Initially, UE 102, which is in DC with MN 104 and SN 106A, communicates 302 UL data PDUs and / or DL ​​data PDUs with MN 104 via PCell, and communicates 302 UL data PDUs and / or DL ​​data PDUs with SN 106A via PSCell (i.e., a cell other than cell 126A). MN 104 determines 504 to configure base station 106A as a C-SN for a conditional SN change of UE 102 from SN 106B to C-SN 106A. MN 104 may determine to do so based on measurement results (multiple) from UE 102 or in response to a conditional SN change required message (e.g., SN Change Required message) from UE 102 to C-SN 106A. In response to the determination, MN 104 transmits 506 an SN Add Request message to C-SN 106A for the conditional SN change procedure. In response to the SN add request message, the C-SN 106A determines 508 to configure a complete C-SN configuration for the conditional SN change from the SN 106B to the C-SN 106A. The C-SN 106A includes a complete configuration indication in the complete C-SN configuration and includes the complete C-SN configuration in the SN add request confirm message. The SN 106A transmits 510 an SN add request confirm message to the MN 104 in response to the SN add request message. The complete C-SN configuration configures the C-PSCell and may configure zero, one or more C-SCells. Then, the MN 104 sends 512 an RRC reconfiguration message including the complete C-SN configuration to the UE 102. In some implementations, the UE 102 may send 514 an RRC reconfiguration complete message to the MN 104 in response to the RRC reconfiguration message. The MN 104 may transmit 516 an SN reconfiguration complete message to the C-SN 106A in response to the RRC reconfiguration complete message.

[0097] In some implementations, the MN 104 may indicate to the base station 106A in the SN add request message that the base station 106A is requested to be the C-SN of the UE 102 .

[0098] The UE 102 detects 518 that a condition (or conditions) for connecting to the C-PSCell 126A is satisfied, and initiates a random access procedure on the C-PSCell 126A in response to the detection. For convenience, the following discussion refers to a condition or configuration in the singular, but it will be understood that it can be one or more conditions, or include one or more configuration parameters. In response to the initiation, the UE 102 performs 520 a random access procedure with the C-SN 106A via the C-PSCell 126A using the random access configuration in the complete C-SN configuration. The UE 102 may disconnect from the SN 106B (i.e., the PSCell of the SN 106B and all (multiple) SCells, if configured) in response to the initiation or detection. In some embodiments, the random access procedure may be a 4-step random access procedure or a 2-step random access procedure. In other embodiments, the random access procedure may be a contention-based random access procedure or a contention-free random access procedure. After the UE 102 successfully completes the random access procedure 520, the UE 102 in the DC with the MN 104 and the SN 106A communicates 522 with the SN 106A via the C-PSCell 126A (i.e., the new PSCell 126A) using the complete C-SN configuration. The UE 102 releases 524 the SN configuration in response to the complete configuration indication. After receiving the SN add request confirmation message, the MN 104 may transmit 526 an interface message to the SN 106B. The SN 106B may release 524 the SN configuration in response to the interface message 526. In some implementations, the interface message may be an SN release request message, an SN state transfer message, or a UE context release message.

[0099] In some implementations, UE 102 may send an RRC message to MN 104 indicating that UE 102 is connected to C-SN 106A, and MN 104 transmits 526 an interface message to SN 106B in response to the RRC message. In other implementations, C-SN 106A may transmit an interface message to MN 104 indicating that UE 102 is already connected to C-SN 106A, and MN 104 transmits 526 an interface message to SN 106B in response to the interface message.

[0100] In some embodiments, if SN 106A finds the identity of UE 102 in a MAC PDU received from UE 102 in the random access procedure 520, then SN 106A identifies UE 102. SN 106A includes the identity of UE 102 in the complete C-SN configuration. In other embodiments, if SN 106A receives a dedicated random access preamble from UE 102 in the random access procedure, then SN 106A identifies UE 102. SN 106A includes the dedicated random access preamble in the complete C-SN configuration.

[0101] In some embodiments, the C-SN 106A may be preconfigured to generate a complete configuration for the C-SN configuration and include a complete configuration indication in the C-SN configuration. In other embodiments, if the C-SN 106A identifies that the SN 106B operates in a different vendor, the C-SN 106A may determine to generate a complete configuration for the C-SN configuration and include a complete configuration indication in the C-SN configuration. In other embodiments, if the C-SN 106A is unable to generate an incremental configuration for the C-SN configuration based on the SN configuration received in the SN add request message, the C-SN 106A may determine to generate a complete configuration for the C-SN configuration and include a complete configuration indication in the C-SN configuration. If the C-SN 106A identifies that the SN 106B operates in the same vendor or is capable of doing so, the C-SN 106A may determine to generate an incremental C-SN configuration in the SN add request confirm message in the conditional SN change procedure.

[0102] Next, Figure 5B shows that it involves something like Figure 5A 550 of a conditional SN change. In this scenario, BS 104 operates as a MN, BS 106A operates as a C-SN, and BS 106B operates as a SN. Events 552, 554, 556, 558, 560, 562, 564, 566, 568, 570, 572, 574, 576, and 578 are similar to those of reference 1. Figure 5A Events discussed are 502, 504, 506, 508, 510, 512, 514, 516, 518, 520, 522, 524, 526, and 528. Figure 5A and Figure 5B The difference between.

[0103] In scenario 550, the MN 104 determines 554 that a complete C-SN configuration is requested, and in response to the determination transmits 556 an SN add request message to request the complete C-SN configuration. In response to the SN add request message, the C-SN 106A generates 558 a complete C-SN configuration that configures the C-PSCell 126A and includes a complete configuration indication. The C-SN 106A then transmits 560 an SN add request confirm message including the complete C-SN configuration to the MN 104.

[0104] In some implementations, MN 104 may be preconfigured to request a complete C-SN configuration in an SN Add Request message in a conditional SN change procedure. In other implementations, if MN 104 identifies that SN 106B is operated by a different vendor than C-SN 106A, MN 104 may determine to request a complete C-SN configuration in an SN Add Request message in a conditional SN change procedure. If MN 104 identifies that SN 106B is operated by the same vendor as a C-SN different from C-SN 106A, MN 104 may determine to request an incremental C-SN configuration in an SN Add Request message in a conditional SN change procedure with that C-SN.

[0105] Next, Fig. 6AAnother scenario 600 involving a conditional PSCell change is shown. In this scenario, BS 104 operates as a MN and BS 106A operates as a SN. Initially, UE 102, which is in a DC with MN 104 and SN 106A, communicates 602 UL data PDUs and / or DL ​​data PDUs with MN 104 via PCell and communicates 602 UL data PDUs and / or DL ​​data PDUs with SN 106A via PSCell (i.e., a cell other than cell 126A) using a first SN configuration. SN 106A determines 604 to configure an incremental C-SN configuration, which configures C-PSCell 126A. The SN 106A may determine to configure the C-PSCell 126A based on one or more measurements received from the UE 102 via the MN 104, one or more measurements received directly from the UE 102 (e.g., via a signaling radio bearer (SRB) established between the UE 102 and the SN 106A or via a physical control channel), or one or more measurements obtained by the SN 106A from measurements of, for example, a signal, control channel, or data channel received from the UE 102, or another suitable event. In response to the determination, the SN 106A transmits 606 an incremental C-SN configuration to the MN 104, which then sends 608 an RRC reconfiguration message including the incremental C-SN configuration to the UE 102. In some implementations, the UE 102 may send 610 an RRC reconfiguration complete message to the MN 104 in response to the RRC reconfiguration message. The MN 104 may transmit 612 an SN reconfiguration complete message to the SN 106A in response to the RRC reconfiguration complete message.

[0106] Later, SN 106A determines to update the first SN configuration. In some embodiments, SN 106A determines to update the first SN configuration based on SN 106A detecting a triggering event. The triggering event may be related to radio resource management. In one embodiment, the triggering event may be one or more measurement results received from UE 102 indicating that a cell is suitable as an SCell of UE 102. In another embodiment, the triggering event may be one or more measurement results received from UE 102 indicating that the SCell of UE 102 is not suitable for UE 102. In yet another embodiment, the triggering event may be SN 106A determining to configure UE 102 to use one or more reference signals for measurement and reporting.

[0107] In response to the determination, the SN 106A generates a second SN configuration, which adds new configuration parameters that are not in the first SN configuration, modifies configuration parameters in the first SN configuration, or releases configuration parameters in the first SN configuration. The second SN configuration may be an incremental SN configuration or a complete SN configuration. In some embodiments, the parameters of the second SN configuration may not overlap with the parameters of the incremental C-SN configuration, so that the SN 106A does not need to expend resources to thereby update the incremental C-SN configuration previously provided to the UE 102 after the second SN configuration is generated. In other embodiments, the parameters of the second SN configuration may overlap with the parameters of the incremental C-SN configuration. In some implementations, the SN 106A may use the incremental C-SN configuration to modify the updated first SN configuration (e.g., remove the new configuration parameters included in the second SN configuration when the triggering event that initially caused the SN 106A to send the second SN configuration is no longer applicable). In this way, when UE 102 communicates with SN 106A via C-PSCell 126A using the incremental C-SN configuration and the updated first SN configuration, UE 102 needs to use only a portion of the updated first SN configuration (e.g., UE 102 does not need to use new configuration parameters removed by the incremental C-SN configuration).

[0108] SN 106A transmits 614 the second SN configuration to MN 104 to update the first SN configuration, and then MN 104 transmits 616 the RRC reconfiguration including the second SN configuration to UE 102. UE 102 updates 618 the first SN configuration according to the second SN configuration, and sends 620 an RRC reconfiguration complete message to MN 104 in response to the RRC reconfiguration message 616. If the second SN configuration is an incremental SN configuration for updating the first SN configuration, UE 102 may add one or more new configuration parameters to the first SN configuration, or release one or more configuration parameters in the first SN configuration according to the second SN configuration. If the second SN configuration is a complete SN configuration, UE 102 replaces the first SN configuration with the second SN configuration to update the first SN configuration. MN 104 may send 622 an SN reconfiguration complete message to SN 106A in response to receiving the RRC reconfiguration complete message. UE 102 in DC with MN 104 and SN 106A uses 624 the updated first SN configuration to communicate with SN 106A. That is, UE 102 uses the second SN configuration to communicate with SN 106A. If the second SN configuration includes new configuration parameters that are not in the first SN configuration, UE 102 adds the new configuration parameters to the first SN configuration. If the second SN configuration modifies the configuration parameters relative to the first SN configuration, UE 102 updates the configuration parameters in the first SN configuration to the modified configuration parameters according to the second SN configuration. If the second SN configuration releases the configuration parameters in the first SN configuration, UE 102 releases the configuration parameters in the first SN configuration.

[0109] The UE 102 detects 626 that the condition (or conditions) for connecting to the C-PSCell 126A is met, and in response to the detection initiates a random access procedure on the C-PSCell 126A.

[0110] For convenience, the following discussion refers to a condition or configuration in the singular, but it will be understood that it can be one or more conditions, or include one or more configuration parameters. In response to the initiation, the UE 102 performs 628 a random access procedure with the SN 106A via the C-PSCell 126A using the random access configuration in the incremental C-SN configuration. The UE 102 may disconnect from the PSCell in response to the initiation or detection 626. In some embodiments, the random access procedure may be a 4-step random access procedure or a 2-step random access procedure. In other embodiments, the random access procedure may be a contention-based random access procedure or a contention-free random access procedure. After the UE 102 successfully completes the random access procedure 628, the UE 102 in the DC with the MN 104 and the SN 106A communicates 630 with the SN 106A via the C-PSCell 126A (i.e., the new PSCell 126A) using at least a portion of the incremental C-SN configuration and the updated first SN configuration. In some embodiments, UE 102 may release the remaining portion of the updated first SN configuration parameters before event 630, so that UE 102 does not use the remaining portion of the updated first SN configuration parameters to communicate with SN 106A at event 630. In other embodiments, UE 102 may also use the remaining portion of the updated first SN configuration parameters to communicate with SN 106A at event 630.

[0111] A "delta" C-SN configuration is not a full configuration and does not include a full configuration indication. UE 102 cannot communicate with SN 106A using only the delta C-SN configuration; UE 102 must also refer to the updated first SN configuration stored in UE 102. The delta C-SN configuration may include one or more configuration parameters for UE 102 to communicate with SN 106A via C-PSCell 126A. Multiple configuration parameters may configure radio resources for UE 102 to communicate with SN 106A via zero, one or more C-PSCells of C-SCell 126A and SN 106A. Multiple configuration parameters may configure or not configure zero, one or more radio bearers. One or more radio bearers may include SRBs and / or (multiple) DRBs. Multiple configuration parameters may include or not include measurement configuration and / or security configuration.

[0112] The first SN configuration may include multiple configuration parameters for UE 102 to communicate with SN 106A via zero, one or more secondary cells (SCells) of PSCell and SN 106A. Multiple configuration parameters may configure radio resources for UE 102 to communicate with SN 106A via zero, one or more SCells of PSCell and SN 106A. Multiple configuration parameters may configure zero, one or more radio bearers. One or more radio bearers may include SRBs and / or (multiple) data radio bearers (DRBs). In some cases, the second SN configuration may modify or release one of the multiple configuration parameters. In other cases, the second SN configuration may add new configuration parameters that are not in the first SN configuration.

[0113] In some embodiments, the SN 106A may include the incremental C-SN configuration in an SN Add Modify Confirm message in response to the SN Modify Request message received from the MN 104, and transmit the SN Modify Request Confirm message to the MN 104 at event 606. In other embodiments, the SN 106A may include the incremental C-SN configuration in an SN Modify Required message, and transmit the SN Modify Required message to the MN 104 at event 606. In some embodiments, the SN 106A may indicate that the SN Modify Request Confirm message or the SN Modify Required message is for a conditional PSCell change.

[0114] In some implementations, the SN 106A includes the conditional configuration of the configuration condition 626 in the incremental C-SN configuration. In other implementations, the MN 104 may include the incremental C-SN configuration and the conditional configuration of the configuration condition 626 in the RRC reconfiguration message 608. The MN 104 may generate the conditional configuration (e.g., at event 606) or receive the conditional configuration from the SN 106A.

[0115] In some embodiments, the incremental C-SN configuration may include configuring a group configuration (CellGroupConfig) IE of the C-PSCell 126A, and may configure zero, one, or more C-SCells of the SN 106A. In one embodiment, the incremental C-SN configuration may be an RRCReconfiguration message, an RRCReconfiguration-IE, or a CellGroupConfig IE in accordance with 3GPP TS 38.331. In other embodiments, the incremental C-SN configuration may include configuring an SCG-ConfigPartSCG-r12 IE of the C-PSCell, and may configure zero, one, or more C-SCells of the SN 106A. In one embodiment, the incremental C-SN configuration may be an RRCConnectionReconfiguration message, an RRCConnectionReconfiguration-IE, or a ConfigPartSCG-r12 IE in accordance with 3GPP TS 36.331.

[0116] In some embodiments, the first / second SN configuration may include a CellGroupConfigIE that configures a PSCell, and may configure zero, one, or more SCells of the SN 106A. In one embodiment, the first / second SN configuration may be an RRCReconfiguration message, an RRCReconfiguration-IE, or a CellGroupConfig IE that complies with 3GPP TS 38.331. In other embodiments, the first / second SN configuration may include an SCG-ConfigPartSCG-r12 IE that configures a PSCell, and may configure zero, one, or more SCells of the SN 106A. In one embodiment, the first / second SN configuration may be an RRCConnectionReconfiguration message, an RRCConnectionReconfiguration-IE, or a ConfigPartSCG-r12 IE that complies with 3GPP TS 36.331.

[0117] In some cases, UE 102 may receive one or more conditions (discussed below in singular form for convenience) in an RRC reconfiguration message or an incremental C-SN configuration at event 608. UE 102 may use the one or more conditions to determine whether to connect to C-PSCell 126A. If UE 102 determines that the conditions are met, UE 102 connects to C-PSCell 126A. If UE 102 does not determine that the conditions are met, UE 102 does not connect to C-PSCell 126A.

[0118] In some embodiments, as shown in FIG. 2 , the SN 106A may be composed of a CU 172 and one or more DUs 174. The DU 174 may generate an incremental C-SN configuration or at least a portion of the incremental C-SN configuration and transmit the incremental C-SN configuration or a portion of the incremental C-SN configuration to the CU 172. In the case where the DU 174 generates at least a portion of the incremental C-SN configuration, the CU 172 may generate the remaining portion of the incremental C-SN configuration. In one embodiment, the DU 174 may perform a random access procedure 628 with the UE 102 and identify the UE 102 in the random access procedure. In another embodiment, the DU 174 may perform a random access procedure 628 with the UE 102 and forward the identity of the UE 102 received in the MAC PDU in the random access procedure to the CU 172. The CU 172 identifies the UE 102 based on the identity of the UE 102. In response to the identification, the CU 172 and the DU 174 communicate with the UE 102 using the incremental C-SN configuration and at least a portion of the updated first SN configuration.

[0119] If SN 106A identifies UE 102 on C-PSCell 126A at event 628, SN 106A begins sending (multiple) downlink control information (DCI) commands, (multiple) reference signals or data on (multiple) physical downlink control channels (PDCCH) to UE 102 via C-PSCell 126A and / or one or more C-SCells (if configured in the incremental C-SN configuration) based on some configuration parameters in at least a portion of the incremental C-SN configuration and / or the updated first SN configuration. If SN 106A identifies UE 102 on C-PSCell 126A at event 628, SN 106A may receive (multiple) signals, (multiple) sounding reference signals, or data on physical uplink control channels (PUCCHs) from UE 102 via C-PSCell 126A and / or one or more C-SCells (if configured in the incremental C-SN configuration) according to some configuration parameters in at least a portion of the incremental C-SN configuration and / or the updated first SN configuration. UE 102 receives (multiple) DCI commands, (multiple) reference signals, or data on PDCCHs from SN 106A via C-PSCell 126A and / or one or more C-SCells (if configured in the incremental C-SN configuration) according to some configuration parameters in at least a portion of the incremental C-SN configuration and / or the updated first SN configuration. The UE 102 may send (multiple) signals, (multiple) sounding reference signals or data on (multiple) PUCCHs to the SN 106A via the C-PSCell 126A and one or more C-SCells (if configured in the incremental C-SN configuration) based on some configuration parameters in the incremental C-SN configuration and / or at least a portion of the updated first SN configuration.

[0120] As described above, before C-PSCell 126A becomes suitable for UE 102, SN 106A pre-configures C-PSCell 126A to UE 102 at events 606 and 608. When C-PSCell 126A becomes suitable for UE 102 (i.e., UE 102 detects corresponding conditions), UE 102 performs a random access procedure with C-PSCell to quickly change PSCell. In contrast to the immediate PSCell change procedure, the conditional PSCell change technique discussed in the present disclosure significantly reduces the latency associated with DC configuration.

[0121] If MN 104 is a gNB, the RRC reconfiguration message and the RRC reconfiguration completion message are RRCReconfiguration message and RRCConnectionReconfigurationComplete message, respectively. If MN 104 is an eNB or ng-eNB, the RRC reconfiguration message and the RRC reconfiguration completion message are RRCReconfiguration message and RRCConnectionReconfigurationComplete message, respectively.

[0122] Next, Figure 6B Scenario 650 is shown involving a conditional C-PSCell change without an SN change (i.e., a conditional change of the PSCell of the SN when the UE is already in DC with both the MN and the SN). In this scenario, BS 104 operates as a MN and BS 106A operates as a SN. Events 652, 654, 668, 674, 676, 678, and 680 in this scenario are similar to those described in reference 6. Fig. 6A Events 602, 604, 606, 618, 624, 626, 628, and 630 are discussed below. Fig. 6A and Figure 6B The difference between the scenes.

[0123] exist Figure 6B In the scenario 650 of FIG. 6 , the SN 106A sends 656 the incremental C-SN configuration directly to the UE 102 in response to the determination 654, rather than transmitting it to the UE via the MN 104. The UE 102 may send an RRC reconfiguration complete message to the SN 106A in response to the incremental C-SN configuration. In some implementations, the SN 106A configures a first SRB to the UE 102 via the MN 104, and sends the incremental C-SN configuration to the UE 102 via the first SRB. For example, the SN 106A transmits an SRB configuration that configures the first SRB (e.g., SRB3) to the MN 104, and the MN 104 sends the SRB configuration to the UE via a second SRB (e.g., SRB1) between the MN 104 and the UE 102. If the incremental C-SN configuration includes an SRB configuration and the UE 102 is connected to the C-PSCell 126A, the UE 102 may reconfigure the SRB configuration in the updated first SN configuration with the SRB configuration in the incremental C-SN configuration. In some implementations, the UE 102 may send an RRC reconfiguration complete message to the SN 106A via the first SRB in response to the incremental C-SN configuration.

[0124] After event 656, SN 106A sends 666 the second SN configuration directly to UE 102, rather than transmitting it to the UE via MN 104. UE 102 may send an RRC reconfiguration complete message to SN 106A in response to the second SN configuration. In some implementations, SN 106A sends the second SN configuration to UE 102 via the first SRB. UE 102 may send an RRC reconfiguration complete message to SN 106A in response to the second SN configuration via the first SRB.

[0125] refer to Fig. 7A , scenario 700 also involves similar Fig. 6A Conditional PSCell change of scenario 600. In this scenario, BS 104 operates as a MN and BS 106A operates as a SN. Fig. 7A All events in are similar to those in reference Fig. 6A All events discussed except event 730. UE 102 in DC with MN 104 and SN 106A communicates 730 with SN 106A via a new PSCell using the delta-C-SN configuration and at least a portion of the first SN configuration (rather than the updated first SN configuration according to the second SN configuration).

[0126] refer to Figure 7B , scenario 750 also involves similar Figure 6B Conditional PSCell change of scenario 650. In this scenario, BS 104 operates as a MN and BS 106A operates as a SN. Figure 7B All events in are similar to those in reference Figure 6B All events discussed except event 780. UE 102 in DC with MN 104 and SN 106A communicates 780 with SN 106A via a new PSCell using the delta-C-SN configuration and at least a portion of the first SN configuration (rather than the updated first SN configuration according to the second SN configuration).

[0127] Next, Fig. 8A Another scenario 800 involving a conditional PSCell change is shown. In this scenario, BS 104 operates as a MN and BS 106A operates as a SN. Events 802-812 in this scenario are similar to those described in reference 802. Fig. 6A Events 602-612, 618, 624, 626, 628, and 630 are discussed below. Fig. 6A and Fig. 8A The difference between the scenes.

[0128] Initially, UE 102 in DC with MN 104 and SN 106A communicates 802 with SN 106A via PSCell using SN configuration, as shown in FIG. Fig. 6A Event 602. SN 106A determines to configure a first incremental C-SN configuration, which configures a first C-PSCell (i.e., different from cell 126A and in Figure 1A 804 a cell not shown in the figure). The SN 106A generates 804 a first incremental C-SN configuration according to the SN configuration. The SN 106A may determine to configure the first C-PSCell based on one or more measurement results received from the UE 102 via the MN 104, or one or more measurement results received directly from the UE 102 (e.g., via a signaling radio bearer (SRB) established between the UE 102 and the SN 106A or via a physical control channel), or one or more measurement results obtained by the SN 106A from measurements of, for example, a signal, a control channel, or a data channel received from the UE 102, or another suitable event. The SN 106A transmits 806 the first incremental C-SN configuration to the MN 104, which then sends 808 an RRC reconfiguration message including the first incremental C-SN configuration to the UE 102. In some embodiments, the UE 102 may send 810 an RRC reconfiguration complete message to the MN 104 in response to the RRC reconfiguration message 810. The MN 104 may transmit 812 an SN reconfiguration complete message in response to the RRC reconfiguration complete message 810 to the SN 106A.

[0129] Later, SN 106A determines to configure a second incremental C-SN configuration, which configures a second C-PSCell (i.e., cell 126A) of SN 106A (not shown in FIG. 1 ). SN 106A generates 814 the second incremental C-SN configuration according to the SN configuration. SN 106A may determine to configure the second C-PSCell based on, for example, one or more measurement results received from UE 102 via MN 104 or via a signaling radio bearer (SRB) established between UE 102 and SN 106A, or another suitable event. SN 106A transmits 816 the second incremental C-SN configuration to MN 104, which then sends 818 an RRC reconfiguration message including the second incremental C-SN configuration to UE 102. In some implementations, UE 102 may send 820 an RRC reconfiguration complete message to MN 104 in response to the RRC reconfiguration message 818. The MN 104 may transmit 822 an SN reconfiguration complete message in response to the RRC reconfiguration complete message 820 to the SN 106A.

[0130] The UE 102 detects 826 that a condition (or conditions) for connecting to the second C-PSCell 126A is met, and initiates a random access procedure on the second C-PSCell 126A in response to the detection. For convenience, the following discussion refers to a condition or configuration in the singular, but it will be understood that it can be one or more conditions, or include one or more configuration parameters. In response to the initiation, the UE 102 performs 828 a random access procedure with the SN 106A via the second C-PSCell 126A using the random access configuration in the second incremental C-SN configuration. The UE 102 may disconnect from the PSCell in response to the initiation or detection. In some embodiments, the random access procedure may be a 4-step random access procedure or a 2-step random access procedure. In other embodiments, the random access procedure may be a contention-based random access procedure or a contention-free random access procedure. After UE 102 successfully completes the random access procedure 828, UE 102 in DC with MN 104 and SN 106A communicates 830 with SN 106A via C-PSCell 126A (i.e., new PSCell 126A) by using the second incremental C-SN configuration and at least a portion of the SN configuration. In some embodiments, UE 102 may release the remaining portion of the SN configuration parameters before event 830, so that UE 102 does not use the remaining portion of the SN configuration parameters to communicate with SN 106A at event 830. In other embodiments, UE 102 may also use the remaining portion of the SN configuration parameters to communicate with SN 106A at event 830.

[0131] UE 102 detects 826 that a condition (or conditions) for connecting to a second C-PSCell is met, and initiates a random access procedure on the second C-PSCell in response to the detection. For convenience, the following discussion refers to conditions or configurations in the singular, but it will be understood that it can be one or more conditions, or include one or more configuration parameters. In response to the initiation, UE 102 performs 828 a random access procedure with SN 106A via the second C-PSCell using the random access configuration in the second incremental C-SN configuration. UE 102 may disconnect from the PSCell in response to the initiation or detection 826. In some embodiments, the random access procedure may be a 4-step random access procedure or a 2-step random access procedure. In other embodiments, the random access procedure may be a contention-based random access procedure or a contention-free random access procedure. After the UE 102 successfully completes the random access procedure 828, the UE 102 in the DC with the MN 104 and the SN 106A communicates 830 with the SN 106A via the second C-PSCell 126 (i.e., the new PSCell) by using the second incremental C-SN configuration and at least a portion of the SN configuration. In some embodiments, the UE 102 may release the remaining portion of the SN configuration parameters before event 830, so that the UE 102 does not use the remaining portion of the SN configuration to communicate with the SN 106A in event 830. In other embodiments, the UE 102 may also use the remaining portion of the SN configuration to communicate with the SN 106A in event 830. In some embodiments, if the UE 102 is connected to the second C-PSCell, the UE 102 may release the first incremental SN configuration. In other embodiments, if the UE 102 is connected to the second C-PSCell, the UE 102 may still maintain the first incremental SN configuration and the SN configuration. By maintaining the first incremental SN configuration, if UE 102 detects conditions for connecting to the first C-PSCell while UE 102 is connected to the second C-PSCell, UE 102 can connect to the first C-PSCell according to the first incremental SN configuration and at least a portion of the SN configuration and communicate with SN 106A via the first C-PSCell. In one embodiment, for example, if the first incremental SN configuration neither releases nor modifies the remaining portion of the SN configuration parameters, or if UE 102 is required to do so as specified by the 3GPP specification, UE 102 can use the remaining portion of the SN configuration parameters to communicate with SN 106A via the first C-PSCell.In another embodiment, the UE 102 may release the remaining portion of the SN configuration parameters, for example, if the first incremental SN configuration releases or modifies the remaining portion of the SN configuration parameters, or if the UE 102 is required to do so as specified by the 3GPP specifications.

[0132] The first / second "incremental" C-SN configuration is not a complete configuration and does not include a complete configuration indication. The UE 102 cannot communicate with the SN 106A using only the first / second incremental C-SN configuration without referring to the SN configuration stored in the UE 102. The first / second incremental C-SN configuration may include one or more configuration parameters for the UE 102 to communicate with the SN 106A via the first C-PSCell / second C-PSCell. Multiple configuration parameters may configure radio resources for the UE 102 to communicate with the SN 106A via zero, one or more C-SCells of the first C-PSCell / second C-PSCell and the SN 106A. Multiple configuration parameters may configure or not configure zero, one or more radio bearers. One or more radio bearers may include SRBs and / or (multiple) DRBs. Multiple configuration parameters may include or not include measurement configurations and / or security configurations. In some embodiments, the SN 106A may include the same configuration parameters having the same values ​​in the first incremental C-SN configuration and the second incremental C-SN configuration.

[0133] The SN configuration may include multiple configuration parameters for UE 102 to communicate with SN 106A via zero, one or more secondary cells (SCells) of the PSCell and SN 106A. The multiple configuration parameters may configure radio resources for UE 102 to communicate with SN 106A via zero, one or more SCells of the PSCell and SN 106A. The multiple configuration parameters may configure zero, one or more radio bearers. The one or more radio bearers may include SRBs and / or (multiple) data radio bearers (DRBs).

[0134] In some embodiments, the SN 106A may include the first incremental C-SN configuration in an SN Add Modify Confirm message in response to the SN Modify Request message received from the MN 104, and transmit the SN Modify Request Confirm message to the MN 104 at Event 806. In other embodiments, the SN 106A may include the first incremental C-SN configuration in an SN Modify Required message, and transmit the SN Modify Required message to the MN 104 at Event 806. In some embodiments, the SN 106A may indicate that the SN Modify Request Confirm message or the SN Modify Required message is for a conditional PSCell change.

[0135] In some embodiments, the SN 106A may include the second incremental C-SN configuration in an SN Add Modify Confirm message in response to the SN Modify Request message received from the MN 104, and transmit the SN Modify Request Confirm message to the MN 104 at Event 816. In other embodiments, the SN 106A may include the second incremental C-SN configuration in an SN Modify Required message, and transmit the SN Modify Required message to the MN 104 at Event 816. In some embodiments, the SN 106A may indicate that the SN Modify Request Confirm message or the SN Modify Required message is for a conditional PSCell change.

[0136] In some embodiments, the SN 106A includes a conditional configuration of the configuration condition 826 in the second incremental C-SN configuration. In other embodiments, the MN 104 may include the second incremental C-SN configuration and the conditional configuration of the configuration condition 826 in the RRC reconfiguration message 818. In some embodiments, the SN 106A includes a conditional configuration that configures the condition for the UE 102 to detect (or evaluate) in the first incremental C-SN configuration. If the UE 102 detects that the condition is met, the UE 102 may connect to the second C-PSCell 126A. The UE may perform a random access procedure on the second C-PSCell 126A to connect to the second C-PSCell 126A. In other embodiments, the MN 104 may include the first incremental C-SN configuration and the conditional configuration of the configuration condition in the RRC reconfiguration message 808. The MN 104 may generate the conditional configuration (e.g., at event 806) or receive the conditional configuration from the SN 106A.

[0137] In some embodiments, the first / second incremental C-SN configuration may include configuring a group configuration (CellGroupConfig) IE of the second C-PSCell 126A, and may configure zero, one, or more C-SCells of the SN 106A. In one embodiment, the incremental C-SN configuration may be an RRCReconfiguration message, an RRCReconfiguration-IE, or a CellGroupConfig IE in accordance with 3GPP TS 38.331. In other embodiments, the incremental C-SN configuration may include configuring an SCG-ConfigPartSCG-r12 IE of the C-PSCell, and may configure zero, one, or more C-SCells of the SN 106A. In one embodiment, the incremental C-SN configuration may be an RRCConnectionReconfiguration message, an RRCConnectionReconfiguration-IE, or a ConfigPartSCG-r12 IE in accordance with 3GPP TS 36.331.

[0138] In some embodiments, the SN configuration may include a CellGroupConfig IE that configures the PSCell, and may configure zero, one, or more SCells of the SN 106A. In one embodiment, the SN configuration may be an RRCReconfiguration message, an RRCReconfiguration-IE, or a CellGroupConfigIE that complies with 3GPP TS38.331. In other embodiments, the SN configuration may include an SCG-ConfigPartSCG-r12 IE that configures the PSCell, and may configure zero, one, or more SCells of the SN 106A. In one embodiment, the SN configuration may be an RRCConnectionReconfiguration message, an RRCConnectionReconfiguration-IE, or a ConfigPartSCG-r12 IE that complies with 3GPP TS 36.331.

[0139] In some cases, UE 102 may receive one or more conditions in an RRC reconfiguration message or a first / second incremental C-SN configuration at event 808 / 818 (discussed in singular form below for convenience). UE 102 may use one or more conditions to determine whether to connect to the first C-PSCell / second C-PSCell. If UE 102 determines that the conditions of the first C-PSCell / second C-PSCell are met, UE 102 is connected to the first C-PSCell / second C-PSCell. If UE 102 does not determine that the conditions of the first C-PSCell / second C-PSCell are met, UE 102 is not connected to the first C-PSCell / second C-PSCell. If UE 102 simultaneously detects that the conditions of the first C-PSCell and the conditions of the second C-PSCell are met, UE 102 is connected to the first C-PSCell or the second C-PSCell. In some embodiments, if one of the first C-PSCell and the second C-PSCell has better signal strength / quality than the other, the UE 102 can connect to the one. In other embodiments, if one of the first C-PSCell and the second C-PSCell has a wider frequency bandwidth than the other, the UE 102 can connect to the one. In other embodiments, if one of the first C-PSCell and the second C-PSCell provides a higher data rate than the other, the UE 102 can connect to the one.

[0140] In some embodiments, as shown in FIG. 2 , the SN 106A may be composed of a CU 172 and one or more DUs 174. The first DU 174 may generate a first incremental C-SN configuration or at least a portion of the first incremental C-SN configuration, and transmit the first incremental C-SN configuration or at least a portion of the first incremental C-SN configuration to the CU 172. In the case where the first DU 174 generates at least a portion of the first incremental C-SN configuration, the CU 172 may generate the remaining portion of the first incremental C-SN configuration. The second DU 174 may generate at least a portion of the second incremental C-SN configuration or at least a portion of the second incremental C-SN configuration, and transmit the second incremental C-SN configuration or at least a portion of the second incremental C-SN configuration to the CU 172. In the case where the second DU 174 generates at least a portion of the second incremental C-SN configuration, the CU 172 may generate the remaining portion of the second incremental C-SN configuration. In one embodiment, the second DU 174 may perform a random access procedure 828 with the UE 102 and identify the UE 102 in the random access procedure. In another embodiment, the second DU 174 may perform a random access procedure 828 with the UE 102 and forward the identity of the UE 102 received in the MAC PDU during the random access procedure to the CU 172. The CU 172 identifies the UE 102 based on the identity of the UE 102. In response to the identification, the CU 172 and the second DU 174 communicate with the UE 102 using the second incremental C-SN configuration and at least a portion of the first SN configuration.

[0141] If SN 106A identifies UE 102 on the second C-PSCell at event 828, SN 106A begins to send (multiple) downlink control information (DCI) commands, (multiple) reference signals, or data on (multiple) physical downlink control channels (PDCCHs) to UE 102 via the second C-PSCell and / or one or more C-SCells (if configured in the second incremental C-SN configuration) according to some configuration parameters in at least a portion of the second incremental C-SN configuration and / or the SN configuration. If SN 106A identifies UE 102 on the second C-PSCell at event 828, SN 106A may receive (multiple) signals, (multiple) sounding reference signals, or data on (multiple) PUCCHs from UE 102 via the second C-PSCell and / or one or more C-SCells (if configured in the second incremental C-SN configuration) according to some configuration parameters in at least a portion of the second incremental C-SN configuration and / or the SN configuration. The UE 102 receives (multiple) DCI commands, (multiple) reference signals, or data on (multiple) PDCCHs from the SN 106A via the second C-PSCell and / or one or more C-SCells (if configured in the second incremental C-SN configuration) according to some configuration parameters in at least a portion of the second incremental C-SN configuration and / or the SN configuration. The UE 102 may send (multiple) signals, (multiple) sounding reference signals, or data on (multiple) PUCCHs to the SN 106A via the second C-PSCell and one or more C-SCells (if configured in the incremental C-SN configuration) according to some configuration parameters in at least a portion of the second incremental C-SN configuration and / or the SN configuration.

[0142] As described above, before the first C-PSCell and / or the second C-PSCell becomes suitable for UE 102, SN 106A pre-configures the first C-PSCell and the second C-PSCell to UE 102 at events 806, 808 and events 816, 818, respectively. When the second C-PSCell becomes suitable for UE 102 (i.e., UE 102 detects the corresponding conditions), UE 102 performs a random access procedure with the second C-PSCell to quickly change PSCell. In contrast to the immediate PSCell change procedure, the conditional PSCell change technique discussed in the present disclosure significantly reduces the latency associated with DC configuration.

[0143] If MN 104 is a gNB, the RRC reconfiguration message and the RRC reconfiguration completion message are RRCReconfiguration message and RRCConnectionReconfigurationComplete message, respectively. If MN 104 is an eNB or ng-eNB, the RRC reconfiguration message and the RRC reconfiguration completion message are RRCReconfiguration message and RRCConnectionReconfigurationComplete message, respectively.

[0144] Next, Figure 8B Scenario 850 is shown involving a conditional C-PSCell change without an SN change (conditional change of PSCell of an SN when the UE is already in DC with both the MN and the SN). In this scenario, BS 104 operates as an MN and BS 106A operates as an SN. Events 852, 854, 864, 868, 876, 878, and 880 in this scenario are similar to those described in reference 1. Fig. 8A Events 802, 804, 814, 818, 826, 828, and 830 are discussed below. Fig. 8A and Figure 8B The difference between the scenes.

[0145] exist Figure 8B In the scenario 850 of FIG. 8 , SN 106A sends 856 the first incremental C-SN configuration directly to UE 102, instead of transmitting it to the UE via MN 104. UE 102 may send an RRC reconfiguration complete message to SN 106A in response to the first incremental C-SN configuration. In some embodiments, SN 106A configures a first SRB to UE 102 via MN 104, and sends the first incremental C-SN configuration to UE 102 via the first SRB. For example, SN 106A transmits an SRB configuration that configures the first SRB (e.g., SRB3) to MN 104, and MN 104 sends the SRB configuration to the UE via a second SRB (e.g., SRB1) between MN 104 and UE 102. In some embodiments, UE 102 may send an RRC reconfiguration complete message to SN 106A via the first SRB in response to the first incremental C-SN configuration.

[0146] After event 856, SN 106A sends 866 the second incremental C-SN configuration directly to UE 102 (e.g., via the first SRB), rather than transmitting it to the UE via MN 104. UE 102 may send an RRC reconfiguration complete message to SN 106A (e.g., via the first SRB) in response to the second incremental C-SN configuration. If the second incremental C-SN configuration includes an SRB configuration and UE 102 is connected to a second C-PSCell, UE 102 may reconfigure the SRB configuration in the SN configuration with the SRB configuration in the second incremental C-SN configuration.

[0147] Next, Fig. 9A Another scenario involving conditional handover is shown 900. In this scenario, for conditional handover, base station (BS) 104 operates as a MN and BS 106B operates as a candidate BS (C-MN).

[0148] exist Fig. 9AIn the scenario 900 of FIG. 1 , UE 102 communicates 902 with MN 104 using a first MN configuration. UE 102 may be in a single connection (SC) with MN 104 or in a DC with MN 104 and SN 106A. MN 104 determines 904 to request a full C-MN configuration for UE 102. The full C-MN configuration configures a candidate PCell (C-PCell) 126B for C-MN 106B. MN 104 may make this determination based on one or more measurement results received directly from the UE (e.g., via a signaling radio bearer (SRB) established between UE 102 and MN 104 or via a physical control channel), or obtained by MN 104 from measurements of, for example, a signal, control channel, or data channel received from UE 102, or another suitable event. In response to the determination, the MN 104 transmits 906 a conditional handover request message including a complete configuration request indication to the C-MN 106B. In response to the conditional handover request message, the C-MN 106B generates a conditional handover command message including a complete C-MN configuration and a first complete configuration indication. Then, the C-MN 106B transmits 910 a conditional handover request confirmation message including the conditional handover command message to the MN 104. The MN 104 transmits 912 an RRC reconfiguration message including the conditional handover command message to the UE 102. The UE 102 may transmit 914 an RRC reconfiguration complete message to the MN 104 in response to the RRC reconfiguration message 912. In some implementations, the first complete configuration indication may be a new field / IE newly defined in 3GPP TS 36.331 or 38.331. If the UE 102 detects that the conditions for connecting to the C-PCell 126B are met, the new field / IE instructs the UE 102 to release the MN configuration and directly use the complete C-MN configuration. In other embodiments, the first complete configuration may be an existing field / IE in 3GPP TS 36.331 or 38.331. If the UE 102 detects that the conditions for connecting to the C-PCell 126B are met, the existing field / IE instructs the UE 102 to release the MN configuration and directly use the complete C-MN configuration.

[0149] In some alternative embodiments, C-MN 106B may include a first complete configuration indication in the conditional handover request confirmation message instead of a complete C-MN configuration. In this case, MN 104 may include a second complete configuration indication in the RRC reconfiguration message 912. In some embodiments, the second complete configuration indication may be a new field / IE newly defined in 3GPP TS 36.331 or 38.331. If UE 102 detects that the conditions for connecting to C-PCell 126B are met, the new field / IE instructs UE 102 to release the MN configuration and directly use the complete C-MN configuration. In other embodiments, the second complete configuration may be an existing field / IE in 3GPP TS 36.331 or 38.331. If UE 102 detects that the conditions for connecting to C-PCell 126B are met, the existing field / IE instructs UE 102 to release the MN configuration and directly use the complete C-MN configuration.

[0150] In some implementations, the conditional handover request message may be a handover request message defined in 3GPP TS 36.423 or TS 38.423, and MN 104 may include a conditional handover request indication in the handover request message. In some implementations, MN 104 may include a first MN configuration in the handover request message. In other implementations, MN 104 may not include the first MN configuration in the handover request message. In this case, MN 104 may not include a complete configuration request indication in the handover request message. If C-MN 106B finds that the MN configuration is not included in the handover request message, C-MN 106B includes the first complete configuration indication in the complete C-MN configuration.

[0151] Later, the UE 102 detects 916 that a condition (or conditions) for connecting to the C-PCell 126B is met, and initiates a random access procedure on the C-PCell 126B in response to the detection. For convenience, the following discussion refers to a condition or configuration in the singular, but it will be understood that it can be one or more conditions, or include one or more configuration parameters. In response to the initiation, the UE 102 performs 918 a random access procedure with the C-MN 106B via the C-PCell 126B using the random access configuration in the complete C-MN configuration. The UE 102 may disconnect from the PCell of the MN 104 in response to the initiation or detection. In some embodiments, the random access procedure may be a 4-step random access procedure or a 2-step random access procedure. In other embodiments, the random access procedure may be a contention-based random access procedure or a contention-free random access procedure. The UE 102 may send 920 a conditional handover complete message to the C-MN 106B via the C-PCell 126B during / after 918 the random access procedure in response to the conditional handover command message.

[0152] After the UE 102 successfully completes the random access procedure 918 or sends a conditional handover completion, the UE 102 communicates 922 with the C-MN 106B via the C-PCell 126B (i.e., the new PCell 126B) using the complete C-MN configuration. The UE 102 releases 924 the first MN configuration in response to the first (or second) complete configuration indication. If the C-MN 106B finds the identity of the UE 102 in the MAC PDU received from the UE 102 in the random access procedure 918, the C-MN 106B identifies the UE 102. The C-MN 106B includes the identity of the UE 102 in the complete C-MN configuration. In other embodiments, if the C-MN 106B receives a dedicated random access preamble from the UE 102 in the random access procedure 918, the C-MN 106B identifies the UE 102. C-MN 106B includes a dedicated random access preamble in the complete C-MN configuration. C-MN 106B transmits 926 an interface message to MN 104 in response to identifying UE 102. In response to or after receiving the interface message, MN 104 releases 928 the first MN configuration.

[0153] In some implementations, the interface message 926 may be a handover success message or a UE context release message. In response to or after receiving the interface message, the MN 104 may transmit an SN state transfer message to the C-MN 106B, and release 928 the first MN configuration after sending the SN state transfer message. In some implementations, the conditional handover command message may be an RRC reconfiguration message, and the conditional handover complete message may be an RRC reconfiguration complete message.

[0154] A "complete" C-MN configuration is a complete and independent configuration (i.e., a complete configuration). The first / second complete configuration indication (information element (IE)) indicates that the "complete" C-MN configuration is a complete and independent configuration (i.e., a complete configuration). The UE 102 can directly use the complete C-MN configuration to communicate with the C-MN 106B according to the first / second complete configuration indication without referring to the first MN configuration. The complete C-MN configuration may include multiple configuration parameters for the UE 102 to communicate with the C-MN 106B via the C-PCell 126B. Multiple configuration parameters may configure radio resources for the UE 102 to communicate with the C-MN 106B via zero, one or more candidate secondary cells (C-SCells) of the C-PCell 126B and the C-MN 106B. Multiple configuration parameters may configure zero, one or more radio bearers. One or more radio bearers may include (multiple) SRBs and / or (multiple) DRBs. (Multiple) SRBs may include SRB1 and / or SRB2.

[0155] The first MN configuration may include a plurality of configuration parameters for UE 102 to communicate with MN 104 via a PCell and zero, one or more secondary cells (SCells) of MN 104. The plurality of configuration parameters may configure radio resources for UE 102 to communicate with MN 104 via a PCell and zero, one or more SCells of MN 104. The plurality of configuration parameters may configure zero, one or more radio bearers. The one or more radio bearers may include (multiple) SRBs and / or (multiple) DRBs. The (multiple) SRBs may include SRB1 and / or SRB2.

[0156] In some implementations, the MN 104 may include the complete C-MN configuration and the conditional configuration of the configuration condition 916 in the RRC reconfiguration message 912.

[0157] In some embodiments, the complete C-MN configuration may include configuring a group configuration (CellGroupConfig) IE of the C-PCell 126B, and may configure zero, one or more C-SCells of the C-MN 106B. In one embodiment, the complete C-MN configuration may be an RRCReconfiguration message, an RRCReconfiguration-IE, or a CellGroupConfig IE in accordance with 3GPP TS 38.331. The first / second complete configuration indication may be a field or IE in accordance with 3GPP TS 38.331. In other embodiments, the complete C-MN configuration may include configuring a RadioResourceConfigDedicated IE and / or a MobilityControlInfo IE of the C-PCell 126B, and may or may not include configuring an SCellToAddModList IE of one or more C-SCells of the C-MN 106B. In one embodiment, the complete C-MN configuration may be an RRCConnectionReconfiguration message or an RRCConnectionReconfiguration-IE in accordance with 3GPP TS 36.331. The first / second complete configuration indication may be a field or IE compliant with 3GPP TS 36.331.

[0158] In some embodiments, the first MN configuration may include a CellGroupConfig IE that configures the PCell, and may configure zero, one, or more SCells of the MN 104. In one embodiment, the MN configuration may be an RRCReconfiguration message, an RRCReconfiguration-IE, or a CellGroupConfig IE that complies with 3GPP TS38.331. In other embodiments, the first MN configuration may include a RadioResourceConfigDedicated IE and / or a MobilityControlInfo IE that configures the PCell, and may or may not include an SCellToAddModList IE that configures one or more SCells of the MN 104.

[0159] In some cases, UE 102 may receive one or more conditions (discussed below in singular form for convenience) in an RRC reconfiguration message at event 912. UE 102 may use the one or more conditions to determine whether to connect to C-PCell 126B. If UE 102 determines that the conditions are met, then UE 102 connects to C-PCell 126B. If UE 102 does not determine that the conditions are met, then UE 102 does not connect to C-PCell 126B.

[0160] In some embodiments, as shown in FIG. 2 , C-MN 106B may consist of CU 172 and one or more DU 174. CU 172 receives a conditional handover request message from MN 104 and transmits a conditional handover request confirmation message. DU 174 may generate a complete C-MN configuration or at least a portion of the complete C-MN configuration and transmit the complete C-MN configuration or at least a portion of the complete C-MN configuration to CU 172. In the case where DU 174 generates at least a portion of the complete C-MN configuration, CU 172 may generate the remaining portion of the complete C-MN configuration. In one embodiment, DU 174 may perform a random access procedure 918 with UE 102 and identify UE 102 in the random access procedure. In another embodiment, DU 174 may perform a random access procedure 918 with UE 102 and forward the identity of UE 102 received in a MAC PDU in the random access procedure to CU 172. CU 172 identifies UE 102 based on the identity of UE 102. In response to the identification, CU 172 and DU 174 communicate with UE 102 using the full C-MN configuration.

[0161] If C-MN 106B identifies UE 102 on C-PCell 126B at event 918, C-MN 106B (i.e., becomes MN 106B) starts sending (multiple) downlink control information (DCI) commands, (multiple) reference signals or data on (multiple) physical downlink control channels (PDCCHs) to UE 102 via C-PCell 126B and / or one or more C-SCells (if configured in the full C-MN configuration) according to some configuration parameters in the full C-MN configuration. If C-MN 106B identifies UE 102 on C-PCell 126B at event 918, MN 106B may receive signal(s), sounding reference signal(s), or data on physical uplink control channel(s) (PUCCH) from UE 102 via C-PCell 126B and / or one or more C-SCells (if configured in the complete C-MN configuration) according to some configuration parameters in the complete C-MN configuration. UE 102 receives DCI command(s), reference signal(s), or data on PDCCH(s) from MN 106B via C-PCell 126B and / or one or more C-SCells (if configured in the complete C-MN configuration) according to some configuration parameters in the complete C-MN configuration. The UE 102 may send signal(s), sounding reference signal(s) or data on PUCCH(s), to the MN 106B via the C-PCell 126B and one or more C-SCells (if configured in the complete C-SN configuration) according to some configuration parameters in the complete C-MN configuration.

[0162] like Fig. 9A As described in , before C-PCell 126B becomes suitable for UE 102, MN 104 and C-MN 106B perform a conditional handover preparation procedure to pre-configure C-PCell 126B for UE 102 at events 904-912. When C-PCell 126B becomes suitable for UE 102 (i.e., UE 102 detects the corresponding conditions), UE 102 performs a random access procedure with C-PCell 126B to quickly hand over to C-PCell 126B. In contrast to the immediate handover procedure, the conditional handover technology discussed in the present disclosure significantly reduces the delay associated with the handover configuration. More specifically, MN 104 can request C-MN 106B to generate a complete MN configuration, so that MN 104 does not need to perform another conditional handover preparation procedure with C-MN 106B due to sending a second MN configuration to UE 102.

[0163] If MN 104 is a gNB, the RRC reconfiguration message and the RRC reconfiguration completion message are RRCReconfiguration message and RRCConnectionReconfigurationComplete message, respectively. If MN 104 is an eNB or ng-eNB, the RRC reconfiguration message and the RRC reconfiguration completion message are RRCReconfiguration message and RRCConnectionReconfigurationComplete message, respectively.

[0164] Next, Fig. 9B Scenario 950 involving conditional handover is shown. In this scenario, base station (BS) 104 operates as a MN and BS 106B operates as a C-MN for conditional handover. Events 952, 954, 956, 958, 960, 962, 964, 966, 968, 970, 972, and 976 in this scenario are similar to those described in reference 1. Fig. 9A The events discussed are 902, 904, 906, 908, 910, 912, 914, 916, 918, 920, 922, and 926. Fig. 9A and Fig. 9B The difference between the scenes.

[0165] MN 104 determines 954 to configure a conditional handover to C-SN 106B for UE 102. In response to the determination, MN 104 transmits 956 a conditional handover request message including the first MN configuration to C-MN 106B. MN 104 does not request a complete C-MN configuration in the conditional handover request message. In response to the conditional handover request message, C-MN 106B generates a conditional handover command message including an incremental C-MN configuration to configure the C-PCell, and then transmits 960 a conditional handover request confirmation including the incremental C-MN configuration to MN 104. MN 104 may generate an incremental C-MN configuration based on the first MN configuration. MN 104 sends 962 an RRC reconfiguration message including the conditional handover command message to UE 102.

[0166] Later, MN 104 determines to update the first MN configuration. In response to the determination, MN 104 generates a second MN configuration, which adds new configuration parameters that are not in the first MN configuration, modifies configuration parameters in the first MN configuration, or releases configuration parameters in the first MN configuration. The second MN configuration can be an incremental MN configuration or a complete MN configuration. MN 104 transmits 982 an RRC reconfiguration including the second MN configuration to UE 102. UE 102 updates 984 the first MN configuration according to the second MN configuration, and sends 986 an RRC reconfiguration complete message to MN 104 in response to the RRC reconfiguration message 982. UE 102 uses 988 the updated first MN configuration to communicate with MN 104.

[0167] If the second MN configuration is a complete MN configuration, UE 102 replaces the first MN configuration with the second MN configuration to update the first MN configuration. If the second MN configuration is an incremental MN configuration and includes new configuration parameters that are not in the first MN configuration, UE 102 adds the new configuration parameters to the first MN configuration. If the second MN configuration is an incremental MN configuration and the configuration parameters are modified relative to the first MN configuration, UE 102 updates the configuration parameters in the first MN configuration to the modified configuration parameters according to the second MN configuration. If the second MN configuration is an incremental MN configuration and the configuration parameters in the first MN configuration are released, UE 102 releases the configuration parameters in the first MN configuration.

[0168] UE 102 detects 966 that a condition (or conditions) for connecting to C-PCell 126B is met, and initiates a random access procedure on C-PCell 126B in response to the detection. For convenience, the following discussion refers to a condition or configuration in the singular, but it will be understood that it can be one or more conditions, or include one or more configuration parameters. In response to the initiation, UE 102 performs 968 a random access procedure with C-MN 106B via C-PCell 126B (i.e., the new PCell) using the random access configuration in the incremental C-MN configuration.

[0169] UE 102 may disconnect from the PCell in response to initiating or detecting 966. After UE 102 successfully completes the random access procedure 968, UE 102 communicates 972 with MN 106B using the incremental C-MN configuration and at least a portion of the updated first MN configuration. In some implementations, UE 102 may release the remaining portion of the updated first MN configuration parameters before event 972, such that UE 102 does not use the remaining portion of the updated first MN configuration parameters to communicate with MN 106B at event 972. In other implementations, UE 102 may also use the remaining portion of the updated first MN configuration parameters to communicate with MN 106B at event 972.

[0170] An "incremental" C-MN configuration is not a complete configuration and does not include a complete configuration indication. UE 102 cannot communicate with MN 106B using only the incremental C-MN configuration; UE 102 must also refer to the updated first SN configuration stored in UE 102. The incremental C-SN configuration may include one or more configuration parameters for UE 102 to communicate with MN 106B via C-PCell 126B. Multiple configuration parameters may configure radio resources for UE 102 to communicate with MN 106B via zero, one or more C-SCells of C-PCell 126B and MN 106B. Multiple configuration parameters may or may not configure zero, one or more radio bearers. One or more radio bearers may include SRBs and / or (multiple) DRBs. Multiple configuration parameters may or may not include measurement configuration and / or security configuration.

[0171] The first MN configuration may include multiple configuration parameters for UE 102 to communicate with MN 104 via PCell and zero, one or more secondary cells (SCells) of MN 104. Multiple configuration parameters may configure radio resources for UE 102 to communicate with MN 104 via PSCell and zero, one or more SCells of MN 104. Multiple configuration parameters may configure zero, one or more radio bearers. One or more radio bearers may include SRBs and / or (multiple) data radio bearers (DRBs). In some cases, the second MN configuration may modify or release one of the multiple configuration parameters. In other cases, the second MN configuration may add new configuration parameters that are not in the first MN configuration.

[0172] In some implementations, the MN 104 may include the incremental C-MN configuration and the conditional configuration of the configuration condition 966 in the RRC reconfiguration message 962 .

[0173] Next, Fig. 10AShows something like Fig. 9A Another scenario 1000 involving conditional handover is described below. In this scenario, base station (BS) 104 operates as a MN for conditional handover. Fig. 9A and Fig. 10A The difference between the scenes.

[0174] exist Fig. 10A In the scenario 1000 of FIG. 1 , UE 102 communicates 1002 with MN 104 via a PCell (not shown in FIG. 1 ) using a first MN configuration. UE 102 may be in a single connection (SC) with MN 104 or in a DC with MN 104 and SN 106A. MN 104 determines 1004 to configure a full C-MN configuration for UE 102. The full C-MN configuration configures C-PCell 124 of MN 104. MN 104 may make this determination based on one or more measurement results received directly from the UE (e.g., via an SRB established between UE 102 and MN 104 or via a physical control channel), or obtained by MN 104 from measurements of, for example, a signal, control channel, or data channel received from UE 102, or another suitable event. In response to the determination, MN 104 generates a conditional handover command message including a full C-MN configuration and a first full configuration indication. Then, MN 104 sends 1012 an RRC reconfiguration message including a conditional handover command message to UE 102. UE 102 may send 1014 an RRC reconfiguration complete message to MN 104 in response to RRC reconfiguration message 1012. In some alternative implementations, MN 104 may include a first complete configuration indication in RRC reconfiguration message 1012 instead of a complete C-MN configuration.

[0175] Later, the UE 102 detects 1016 that a condition (or conditions) for connecting to the C-PCell 124 is met, and initiates a random access procedure on the C-PCell 124 in response to the detection. For convenience, the following discussion refers to a condition or configuration in the singular, but it will be understood that it can be one or more conditions, or include one or more configuration parameters. In response to the initiation, the UE 102 performs 1018 a random access procedure with the MN 104 via the C-PCell 124 using the random access configuration in the complete C-MN configuration. The UE 102 may disconnect from the PCell of the MN 104 in response to the initiation or detection 1016. In some embodiments, the random access procedure may be a 4-step random access procedure or a 2-step random access procedure. In other embodiments, the random access procedure may be a contention-based random access procedure or a contention-free random access procedure. The UE 102 may send 1020 a conditional handover complete message to the MN 104 via the C-PCell 124 during / after the random access procedure 1018 in response to the conditional handover command message.

[0176] After the UE 102 successfully completes the random access procedure 1018 or sends a conditional handover complete message, the UE 102 communicates 1022 with the MN 104 via the C-PCell 124 (i.e., the new PCell 124) by using the complete C-MN configuration. The UE 102 releases 1024 the first MN configuration in response to the first complete configuration indication. If the MN 104 finds the identity of the UE 102 in the MAC PDU received from the UE 102 in the random access procedure 1018, the MN 106B recognizes that the UE 102 is connected to the C-PCell 124. The MN 104 includes the identity of the UE 102 in the complete C-MN configuration. In other embodiments, if the MN 104 receives a dedicated random access preamble from the UE 102 in the random access procedure 1018, the MN 104 recognizes that the UE 102 is connected to the C-PCell 124. The MN 104 includes the dedicated random access preamble in the complete C-MN configuration. In response to or after identifying that the UE 102 is connected to the C-Pcell 124, the MN 104 releases 1028 the first MN configuration.

[0177] A "full" C-MN configuration is a complete and independent configuration (i.e., a complete configuration). The first / second complete configuration indication (information element (IE)) indicates that the "full" C-MN configuration is a complete and independent configuration (i.e., a complete configuration). UE 102 can directly use the complete C-MN configuration to communicate with MN 104 according to the first complete configuration indication without referring to the first MN configuration. The complete C-MN configuration may include multiple configuration parameters for UE 102 to communicate with MN via C-PCell 124. The multiple configuration parameters may configure radio resources for UE 102 to communicate with MN 104 via C-PCell 124 and zero, one or more candidate secondary cells (C-SCells) of MN 104. The multiple configuration parameters may configure zero, one or more radio bearers. The one or more radio bearers may include (multiple) SRBs and / or (multiple) DRBs. The (multiple) SRBs may include SRB1 and / or SRB2. Examples of the first MN configuration, the second MN configuration, and the complete C-MN configuration may refer to Fig. 9A Description.

[0178] In some implementations, the MN 104 may include the complete C-MN configuration and the conditional configuration of the configuration condition 1016 in the RRC reconfiguration message 1012.

[0179] In some cases, UE 102 may receive one or more conditions (discussed below in singular form for convenience) in an RRC reconfiguration message at event 1012. UE 102 may use the one or more conditions to determine whether to connect to C-PCell 124. If UE 102 determines that the conditions are met, then UE 102 connects to C-PCell 124. If UE 102 does not determine that the conditions are met, then UE 102 does not connect to C-PCell 124.

[0180] In some embodiments, as shown in FIG. 2 , the MN 104 may be composed of a CU 172 and one or more DUs 174. The first DU may generate a first MN configuration and a second MN configuration. The second DU 174 may generate a complete C-MN configuration or at least a portion of the complete C-MN configuration, and transmit the complete C-MN configuration or at least a portion of the complete C-MN configuration to the CU 172. In the case where the second DU 174 generates at least a portion of the complete C-MN configuration, the CU 172 may generate the remaining portion of the complete C-MN configuration. In one embodiment, the second DU 174 may perform a random access procedure 1018 with the UE 102 and identify the UE 102 in the random access procedure 1018. In another embodiment, the second DU 174 may perform a random access procedure 1018 with the UE 102 and forward the identity of the UE 102 received in the MAC PDU in the random access procedure to the CU 172. The CU 172 identifies the UE 102 based on the identity of the UE 102. In response to the identification, the CU 172 and the second DU 174 communicate with the UE 102 using the full C-MN configuration.

[0181] If the MN 104 identifies the UE 102 on the C-PCell 124 at event 1018, the MN 104 starts to send (multiple) downlink control information (DCI) commands, (multiple) reference signals, or data on (multiple) PDCCHs to the UE 102 via the C-PCell 124 and / or one or more C-SCells (if configured in the complete C-MN configuration) according to some configuration parameters in the complete C-MN configuration. If the MN 104 identifies the UE 102 on the C-PCell 124 at event 1018, the MN 104 may receive (multiple) signals, (multiple) sounding reference signals, or data on (multiple) PUCCHs from the UE 102 via the C-PCell 124 and / or one or more C-SCells (if configured in the complete C-MN configuration) according to some configuration parameters in the complete C-MN configuration. The UE 102 receives (multiple) DCI commands, (multiple) reference signals, or data on (multiple) PDCCHs from the MN 104 via the C-PCell 124 and / or one or more C-SCells (if configured in the complete C-MN configuration) according to some configuration parameters in the complete C-MN configuration. The UE 102 may send (multiple) signals, (multiple) sounding reference signals, or data on (multiple) PUCCHs to the MN 104 via the C-PCell 124 and one or more C-SCells (if configured in the complete C-SN configuration) according to some configuration parameters in the complete C-MN configuration.

[0182] like Fig. 10A As described in , before C-PCell 124 becomes suitable for UE 102, MN 104 pre-configures C-PCell 124 for UE 102 at events 1004-1012. When C-PCell 124 becomes suitable for UE 102 (i.e., UE 102 detects the corresponding conditions), UE 102 performs a random access procedure with C-PCell 124 to quickly handover to C-PCell 124. In contrast to the immediate handover procedure, the conditional handover technology discussed in the present disclosure significantly reduces the delay associated with the handover configuration. More specifically, MN 104 can generate a complete MN configuration for conditional handover, so that MN 104 does not need to transmit another RRC reconfiguration message that updates the incremental C-MN configuration stored in the UE due to sending a second MN configuration to UE 102.

[0183] If MN 104 is a gNB, the RRC reconfiguration message and the RRC reconfiguration completion message are RRCReconfiguration message and RRCConnectionReconfigurationComplete message, respectively. If MN 104 is an eNB or ng-eNB, the RRC reconfiguration message and the RRC reconfiguration completion message are RRCReconfiguration message and RRCConnectionReconfigurationComplete message, respectively.

[0184] Next, Fig. 10B Shows something like Fig. 10A and Fig. 9B Another scenario 1050 involving conditional handover is described in detail. In this scenario, base station (BS) 104 operates as a MN for conditional handover. The events in this scenario are similar to those in reference Fig. 9B and Fig. 10A The following discussion Fig. 10B and Fig. 9B and 10A The difference between the scenes.

[0185] exist Fig. 10BIn a scenario 1050 of FIG. 1 , UE 102 communicates 1052 with MN 104 via a PCell (not shown in FIG. 1 ) using a first MN configuration. UE 102 may be in a single connection (SC) with MN 104 or in a DC with MN 104 and SN 106A. MN 104 determines 1054 to configure an incremental C-MN configuration for UE 102. The incremental C-MN configuration configures C-PCell 124 of MN 104. MN 104 may make this determination based on one or more measurement results received directly from the UE (e.g., via an SRB established between UE 102 and MN 104 or via a physical control channel), or obtained by MN 104 from measurements of, for example, a signal, control channel, or data channel received from UE 102, or another suitable event. In response to the determination, MN 104 generates 1058 a conditional handover command message including the incremental C-MN configuration. MN 104 generates an incremental C-MN configuration according to the first MN configuration. MN 104 then sends 1062 an RRC reconfiguration message including a conditional handover command message to UE 102. UE 102 may send 1014 an RRC reconfiguration complete message to MN 104 in response to the RRC reconfiguration message 1012.

[0186] Later, MN 104 determines to update the first MN configuration. In response to the determination, MN 104 generates a second MN configuration, which adds new configuration parameters that are not in the first MN configuration, modifies configuration parameters in the first MN configuration, or releases configuration parameters in the first MN configuration. MN 104 transmits 1082 an RRC reconfiguration including the second MN configuration to UE 102. UE 102 updates 1084 the first SN configuration according to the second SN configuration, and sends 1086 an RRC reconfiguration complete message to MN 104 in response to the RRC reconfiguration message 1082. UE 102 uses 1088 the updated first MN configuration to communicate with MN 104.

[0187] If the second MN configuration includes new configuration parameters that are not in the first MN configuration, UE 102 adds the new configuration parameters to the first MN configuration. If the second MN configuration modifies configuration parameters relative to the first MN configuration, UE 102 updates the configuration parameters in the first MN configuration to the modified configuration parameters according to the second MN configuration. If the second MN configuration releases configuration parameters in the first MN configuration, UE 102 releases the configuration parameters in the first MN configuration.

[0188] UE 102 detects 1066 the satisfaction of a condition (or conditions) for connecting to C-PCell 126B, and in response to the detection initiates a random access procedure on C-PCell 124. For convenience, the following discussion refers to a condition or configuration in the singular, but it will be understood that it can be one or more conditions, or include one or more configuration parameters. In response to the initiation, UE 102 performs 1068 a random access procedure with MN 104 via C-PCell 124 (i.e., the new PCell) using the random access configuration in the incremental C-MN configuration.

[0189] UE 102 may disconnect from the PCell in response to initiating or detecting 1066. After UE 102 successfully completes the random access procedure 1068, UE 102 communicates 1072 with MN 104 using the incremental C-MN configuration and at least a portion of the updated first MN configuration. In some implementations, UE 102 may release the remaining portion of the updated first MN configuration parameters before event 1072, such that UE 102 does not use the remaining portion of the updated first MN configuration to communicate with MN 104 at event 1072. In other implementations, UE 102 may also use the remaining portion of the updated first MN configuration parameters to communicate with MN 104 at event 1072.

[0190] The "incremental" C-MN configuration is not a complete configuration and does not include a complete configuration indication. The UE 102 cannot use the incremental C-MN configuration alone to communicate with the MN 104. Instead, the UE 102 needs to refer to the incremental C-MN configuration and the updated first SN configuration stored in the UE 102. The incremental C-SN configuration may include one or more configuration parameters for the UE 102 to communicate with the MN 104 via the C-PCell 124. Multiple configuration parameters may configure radio resources for the UE 102 to communicate with the MN 104 via zero, one or more C-SCells of the C-PCell 124 and the MN 104. Multiple configuration parameters may or may not configure zero, one or more radio bearers. One or more radio bearers may include SRBs and / or (multiple) DRBs. Multiple configuration parameters may or may not include measurement configurations and / or security configurations.

[0191] The first MN configuration may include multiple configuration parameters for UE 102 to communicate with MN 104 via PCell and zero, one or more secondary cells (SCells) of MN 104. Multiple configuration parameters may configure radio resources for UE 102 to communicate with MN 104 via PSCell and zero, one or more SCells of MN 104. Multiple configuration parameters may configure zero, one or more radio bearers. One or more radio bearers may include SRBs and / or (multiple) data radio bearers (DRBs). In some cases, the second MN configuration may modify or release one of the multiple configuration parameters. In other cases, the second MN configuration may add new configuration parameters that are not in the first MN configuration.

[0192] In some implementations, the MN 104 may include the incremental C-MN configuration and the conditional configuration of the configuration condition 1066 in the RRC reconfiguration message 1062 .

[0193] Next, Fig.11A An example scenario involving a conditional PSCell change procedure before the UE 102 detects a failure in connection with the PSCell is shown.

[0194] First reference Fig.11A In scenario 1100, UE 102 is in DC with MN 104 and SN 106A, communicates with SN 106A via PSCell using SN configuration, and receives C-SN configuration (e.g., full C-SN configuration, incremental C-SN configuration) for configuring C-PSCell and any conditions associated with conditional PSCell change from SN 106A or MN 104, which is similar to events 340, 390, 440, 640, 690, 740, 741, 790, 840 and 890.

[0195] Subsequently, the UE 102 detects 1114 a failure in the connection with the PSCell. In some embodiments, the UE 102 transmits 1116 an SCG failure indication to the MN 104. In some embodiments, the UE 102 consistently transmits 1116 an SCG failure indication. And in other embodiments, the UE 102 omits transmitting the SCG failure indication when the UE 102 has an available C-PSCell to restore the connection.

[0196] In response to detecting the failure, UE 102 detects 1118 whether C-PSCell is suitable. That is, if UE 102 detects that the (multiple) conditions for connecting to C-PSCell are met, UE 102 performs a random access procedure with SN 106A via C-PSCell using (multiple) random access configurations in the C-SN configuration, which is similar to events 316, 366, 416, 628, 728, 778, 828, and 878. As a result, UE 102 is in DC with MN 104 and SN 106A via C-PSCell by using the C-SN configuration, which is similar to events 318, 368, 418, 630, 730, 780, 830, and 880.

[0197] If the UE 102 detects that the conditions for connecting to the C-PSCell are not met, the UE 102 maintains 1124 the connection with the MN 104. In some embodiments, the UE 102 starts a timer at event 1118 to set a time period for connecting to a suitable C-PSCell. If a suitable C-PSCell is not detected and connected to within a preconfigured time period, the UE 102 stops its search for a suitable C-PSCell and maintains 1124 the connection with the MN 104.

[0198] Next, Fig. 11B An example scenario involving a conditional SN change procedure before the UE 102 detects a failure in connection with the PSCell is shown.

[0199] Initially, UE 102, which is in DC with MN 104 and SN 106A, communicates 1152 data with MN 104 via PCell and communicates 1152 data with SN 106A via PSCell (i.e., a cell different from cell 126A), similar to events 502 and 552. MN 104 transmits 1154 an SN add request message to C-SN 106A for a conditional SN change procedure, similar to events 506 and 556. In response to the SN add request message, C-SN 106A generates a complete C-SN configuration for a conditional SN change from SN 106B to C-SN 106A, includes a complete configuration indication in the complete C-SN configuration, and includes the complete C-SN configuration in an SN add request confirm message. SN 106A transmits 1156 an SN add request confirm message to MN 104 in response to the SN add request message, similar to events 510 and 560. MN 104 then sends 1158 an RRC reconfiguration message including the complete C-SN configuration to UE 102, similar to events 512 and 562. In some implementations, UE 102 may send 1160 an RRC reconfiguration complete message to MN 104 in response to the RRC reconfiguration message, similar to events 514 and 564. MN 104 may send 1162 an SN reconfiguration complete message to C-SN 106A in response to the RRC reconfiguration complete message, similar to events 516 and 566.

[0200] Subsequently, UE 102 detects 1164 a failure in connection with the PSCell, which is similar to event 1114. In some embodiments, UE 102 transmits 1166 an SCG failure indication to MN 104, which is similar to event 1116.

[0201] In response to detecting the failure, UE 102 detects 1168 whether C-PSCell is suitable, which is similar to event 1118. That is, if UE 102 detects that the condition(s) for connecting to C-PSCell are met, UE 102 performs 1170 a random access procedure with C-SN 106A via C-PSCell using the random access configuration(s) in the C-SN configuration. As a result, UE 102 is in 1172 a DC with MN 104 and C-SN 106A via C-PSCell using the C-SN configuration.

[0202] Fig.12 An example method 1200 is depicted that the SN 106A or another suitable SN may implement for initiating a conditional PSCell change procedure.

[0203] Method 1200 begins at block 1202, where SN 106A communicates with UE 102 via PSCell using SN configuration (event 302). SN 106A then determines to configure C-PSCell at block 1204 (events 304, 404, 508), and generates a complete C-SN configuration and a complete configuration indication for configuring C-PSCell at block 1206. Subsequently, SN 106A sends the complete C-SN configuration and the complete configuration indication to UE 102 at block 1208 (events 306, 356, 408, 510, 560).

[0204] Fig.13A An example method 1300 is depicted that the MN 104 or another suitable MN may implement for initiating a conditional PSCell change procedure.

[0205] Method 1300 begins at block 1302, where MN 104 communicates with UE 102 via PCell, and UE 102 communicates with SN 106A via PSCell using SN configuration (events 302, 352, 502, 552). MN 104 then receives a complete C-SN configuration and a complete configuration indication configuring a C-PSCell from SN 106A or C-SN 106A at block 1304 (events 306, 356, 510). Subsequently, MN 104 sends the complete C-SN configuration and a second complete configuration indication to UE 102 at block 1306 (events 308, 358, 512).

[0206] Fig. 13B An example method 1350 is depicted that the MN 104 or another suitable MN may implement for initiating a conditional PSCell change procedure.

[0207] Method 1350 begins at block 1352, where MN 104 communicates with UE 102 via PCell, and UE 102 communicates with SN 106A via PSCell using SN configuration (events 302, 352, 502, 552). MN 104 requests C-SN 106A to generate a complete C-SN configuration for UE 102 at block 1354 (event 554). MN 104 then receives a complete C-SN configuration and a complete configuration indication configuring C-PSCell from C-SN 106A at block 1356 (event 560). Subsequently, MN 104 sends the complete C-SN configuration and a second complete configuration indication to UE 102 at block 1356 (event 562).

[0208] Fig.14An example method 1400 is depicted that the UE 102 or another suitable UE may implement for initiating a conditional PSCell change procedure.

[0209] Method 1400 begins at block 1402, where UE 102 communicates with SN 106A via PCell using SN configuration while in DC with MN 104 (events 502, 552). UE 102 then receives a complete C-SN configuration and a complete configuration indication configuring a C-PSCell at block 1404 (events 512, 562). Subsequently, UE 102 detects at block 1406 that the condition(s) for connecting to the C-PSCell are satisfied (events 518, 568). UE 102 then performs a random access procedure with C-SN 106A on C-PSCell using the random access configuration(s) in the complete C-SN configuration at block 1408 (events 520, 570). UE 102 then communicates with C-SN 106A using the complete C-SN configuration at block 1410 without using the SN configuration (events 522, 572).

[0210] Fig.15 An example method 1500 is depicted that the SN 106A or another suitable SN may implement for initiating a conditional PSCell change procedure.

[0211] Method 1500 begins at block 1502, where SN 106A communicates with UE 102 via PSCell using a first SN configuration (events 602, 652). Then, SN 106A transmits a first incremental C-SN configuration configuring C-PSCell to UE 102 at block 1504 (events 606, 656). Then, SN 106A sends a second SN configuration to UE 102 at block 1506 (events 614, 666) to update the first SN configuration, so that UE 102 updates the first SN configuration according to the second SN configuration (events 618, 668). SN 106A communicates with UE 102 using the updated first SN configuration at block 1508 (events 624, 674). Subsequently, SN 106A performs a random access procedure with UE 102 on C-PSCell using the random access configuration(s) in the first incremental C-SN configuration at block 1510 (events 628, 678). SN 106A communicates with UE 102 using the first incremental C-SN configuration and at least a portion of the updated first SN configuration at block 1512 (events 630, 680).

[0212] Fig.16An example method 1600 is depicted that the UE 102 or another suitable UE may implement for initiating a conditional PSCell change procedure.

[0213] Method 1600 begins at block 1602, where UE 102 communicates with SN 106A via a PSCell using a first SN configuration while in DC with MN 104 (events 602, 652). UE 102 then receives a first incremental C-SN configuration configuring a C-PSCell at block 1604 (events 608, 656). UE 102 then receives a second SN configuration configuring the C-PSCell at block 1606 (events 616, 666), such that UE 102 updates the first SN configuration according to the second SN configuration at block 1608 (events 618, 668). UE 102 communicates with SN 106A using the updated first SN configuration at block 1610 (events 624, 674). Subsequently, UE 102 detects at block 1611 that conditions for connecting to the C-PSCell are met (events 626, 676), and in response, performs a random access procedure with SN 106A on the C-PSCell using the random access configuration(s) in the first incremental C-SN configuration at block 1612 (events 628, 678). UE 102 communicates with SN 106A using the first incremental C-SN configuration and at least a portion of the updated first SN configuration at block 1614 (events 630, 680).

[0214] Fig.17 An example method 1700 is depicted that the SN 106A or another suitable SN may implement for initiating a conditional PSCell change procedure.

[0215] Method 1700 begins at block 1702, where SN 106A communicates with UE 102 via PSCell using a first SN configuration (events 702, 752). Then, SN 106A transmits a first incremental C-SN configuration configuring C-PSCell to UE 102 at block 1704 (events 706, 756). Then, SN 106A sends a second SN configuration to UE 102 at block 1706 (events 714, 766) to update the first SN configuration, so that UE 102 updates the first SN configuration according to the second SN configuration (events 718, 768). SN 106A communicates with UE 102 using the updated first SN configuration at block 1708 (events 724, 774). Subsequently, SN 106A performs a random access procedure with UE 102 on C-PSCell using the random access configuration(s) in the first incremental C-SN configuration at block 1710 (events 728, 778). SN 106A communicates with UE 102 using the first incremental C-SN configuration and at least a portion of the first SN configuration at block 1712 (events 730, 780).

[0216] Fig.18 An example method 1800 is depicted that the UE 102 or another suitable UE may implement for initiating a conditional PSCell change procedure.

[0217] Method 1800 begins at block 1802, where UE 102 communicates with SN 106A via a PSCell using a first SN configuration while in DC with MN 104 (events 702, 752). UE 102 then receives a first incremental C-SN configuration configuring a C-PSCell at block 1804 (events 708, 756). UE 102 then receives a second SN configuration updating the first SN configuration at block 1806 (events 716, 766), such that UE 102 updates the first SN configuration according to the second SN configuration at block 1808 (events 718, 768). UE 102 communicates with SN 106A using the updated first SN configuration at block 1810 (events 724, 774). UE 102 then detects at block 1812 that conditions for connecting to the C-PSCell are met (events 726, 776), and in response, performs a random access procedure with SN 106A on the C-PSCell using the random access configuration(s) in the first incremental C-SN configuration at block 1814 (events 728, 778). UE 102 communicates with SN 106A using the first incremental C-SN configuration and at least a portion of the first SN configuration at block 1816 (events 730, 780).

[0218] Next, Fig.19 An example method 1900 is depicted for a conditional PSCell change procedure before the UE 102 detects a failure in connection with the PSCell.

[0219] Method 1900 starts at box 1902, where UE 102 is in DC with MN 104 and SN 106A, communicates with SN 106A via PSCell using SN configuration, and receives C-SN configuration (e.g., full C-SN configuration, incremental C-SN configuration) for configuring C-PSCell and any (multiple) conditions associated with conditional PSCell change from SN 106A via RRC reconfiguration message at box 1904, which is similar to events 340, 390, 440, 640, 690, 740, 741, 790, 840 and 890.

[0220] The UE 102 then detects a failure in connection with the PSCell at block 1906 .

[0221] In response to detecting the failure, UE 102 detects whether the C-PSCell is suitable at block 1908. That is, if UE 102 detects that the condition(s) for connecting to the C-PSCell are satisfied, UE 102 performs a random access procedure with SN 106A via C-PSCell using the random access configuration(s) in the C-SN configuration at block 1910, similar to events 316, 366, 416, 628, 728, 778, 828, and 878. As a result, UE 102 communicates with SN 106A via C-PSCell using the C-SN configuration at block 1912, similar to events 318, 368, 418, 630, 730, 780, 830, and 880.

[0222] If the UE 102 detects that the condition(s) for connecting to the C-PSCell are not met, the UE 102 maintains the connection with the MN 104 at block 1914 .

[0223] Next, Fig. 20 An example method 2000 for performing an immediate PCell change (i.e., an immediate handover), an immediate PSCell change (i.e., an immediate SN change), or a conditional PSCell change (with or without an SN change) is depicted, and the method 2000 may be implemented in a suitable base station acting as a MN, SN, but not a C-SN. For convenience, the method 2000 is discussed below with reference to the MN 104, SN 106A, and UE 102 operating in the wireless communication system 100.

[0224] Method 2000 starts at block 2002, where MN 104 or SN 106A receives one or more measurement results (measurement result(s)) of at least one cell from UE 102. At block 2004, MN 104 or SN 106A determines (i.e., checks or detects) whether the cell satisfies a condition for an immediate PCell change or satisfies a condition for an immediate PSCell change based on the measurement result(s) of the cell in the received measurement result(s).

[0225] If the conditions for an immediate PCell change are met, the MN 104 sends an RRC reconfiguration message including a base station configuration (e.g., MN configuration) that configures the cell as a new PCell to the UE 102 at block 2006. If the conditions for an immediate PSCell change are met, the MN 104 or the SN 106A sends an RRC reconfiguration message including a base station configuration (e.g., SN configuration) that configures the cell as a new PSCell to the UE 102 at block 2006. In either case, upon receiving the RRC reconfiguration message, the UE 102 connects to the base station (e.g., C-MN for immediate handover or SN 106A / C-SN for immediate PSCell change) by performing a random access procedure with the base station.

[0226] If the conditions for immediate PCell change or immediate PSCell change are not met, the MN 104 or SN 106A determines at box 2008 whether the cell meets the conditions for conditional PCell change or conditional PSCell change based on the measurement result(s) of the cell in the received measurement result(s).

[0227] If MN 104 determines that the cell satisfies the conditions for conditional PCell change (events 1004, 1054), MN 104 performs a conditional PCell change procedure with at least another base station (e.g., C-MN) covering the cell to obtain a base station configuration (e.g., C-MN configuration). Subsequently, MN 104 sends an RRC reconfiguration message including a C-MN configuration for configuring the cell as a C-PCell to UE 102 (events 1012, 1062). If MN 104 or SN 106A determines that the cell satisfies the conditions for a conditional PSCell change, MN 104 or SN 106A determines to perform a conditional PSCell change procedure with SN 106A (for a PSCell change procedure without SN change) or C-SN (for a PSCell change procedure with SN change) covering the cell to obtain a base station configuration (e.g., C-SN configuration) (events 304, 354, 404, 504, 508, 554, 558, 604, 654, 704, 754, 804, 854, 864). Subsequently, MN 104 or SN 106A sends an RRC reconfiguration message to UE 102, the RRC reconfiguration message including a C-SN configuration for configuring the cell as a C-PSCell (events 308, 358, 408, 512, 562, 608, 656, 708, 756, 808, 858, 866). In some embodiments, MN 104 or SN 106A may include (multiple) conditions for connecting to a C-PCell or C-PSCell in one or more RRC reconfiguration messages.

[0228] The user equipment (e.g., UE 102) in which the technology of the present disclosure can be implemented can be any suitable device capable of wireless communication, such as a smart phone, a tablet computer, a laptop computer, a mobile game console, a point of sale (POS) terminal, a health monitoring device, a drone, a camera, a media streaming dongle or another personal media device, a wearable device (such as a smart watch), a wireless hotspot, a femtocell base station, or a broadband router. In addition, in some cases, the user equipment can be embedded in an electronic system, such as embedded in a host or an advanced driver assistance system (ADAS) of a vehicle. In addition, the user equipment can be operated as an Internet of Things (IoT) device or a mobile Internet device (MID). Depending on the type, the user equipment may include one or more general-purpose processors, a computer-readable memory, a user interface, one or more network interfaces, one or more sensors, etc.

[0229] Certain embodiments are described in the present disclosure as including logic or multiple components or modules. A module may be a software module (e.g., a code or machine-readable instruction stored on a non-transitory machine-readable medium) or a hardware module. A hardware module is a tangible unit that is capable of performing certain operations and may be configured or arranged in a particular manner. A hardware module may include dedicated circuits or logic that are permanently configured (e.g., as a dedicated processor, such as a field programmable gate array (FPGA) or an application-specific integrated circuit (ASIC), a digital signal processor (DSP), etc.) to perform certain operations. A hardware module may also include programmable logic or circuits (e.g., contained in a general-purpose processor or other programmable processor) that are temporarily configured by software to perform certain operations. The decision to implement a hardware module in a dedicated and permanently configured circuit or in a temporarily configured (e.g., configured by software) circuit may be driven by cost and time considerations.

[0230] When implemented in software, the techniques may be provided as part of an operating system, as a library used by multiple applications, as a specific software application, etc. The software may be executed by one or more general-purpose processors or one or more special-purpose processors.

[0231] After reading this disclosure, those skilled in the art will appreciate additional and alternative structural and functional designs for handling mobility between base stations through the principles disclosed herein. Therefore, although specific embodiments and applications have been shown and described, it should be understood that the disclosed embodiments are not limited to the precise construction and components disclosed herein. Various modifications, changes and variations may be made to the arrangement, operation and details of the methods and group leaders disclosed herein without departing from the spirit and scope defined in the appended claims, which will be apparent to those of ordinary skill in the art.

[0232] Aspect 1. A method in a base station, which is capable of providing a complete configuration associated with a radio connection to a user equipment and an incremental configuration that the user equipment can apply to a previously received configuration, the method comprising: determining, by processing hardware of the base station and while the user equipment is operating in a cell covered by the base station using the previously received configuration, to configure a complete configuration for the user equipment; identifying, by the processing hardware, at least a candidate cell for the complete configuration; and sending, by the processing hardware and to the user equipment, the complete configuration and an indication of a set of one or more conditions to be met before the user equipment communicates with the base station via the candidate cell using the complete configuration.

[0233] Aspect 2. The method according to aspect 1, wherein the base station is a secondary node (SN) operating in dual connectivity (DC) with the user equipment and a primary node (MN).

[0234] Aspect 3. A method according to aspect 1 or 2, wherein the sending includes including an indication of the complete configuration to the user equipment.

[0235] Aspect 4. The method according to aspect 2 or 3, wherein the sending comprises transmitting the complete configuration to the user equipment via an RRC reconfiguration message from the MN.

[0236] Aspect 5. The method according to aspect 2 or 3, wherein the sending provides complete configuration directly from the SN to the user equipment.

[0237] Aspect 6. A method according to any one of aspects 1-5, wherein the sending further comprises providing an indication of a set of one or more conditions to be satisfied before the user equipment communicates with the base station using the complete configuration.

[0238] Aspect 7. A method according to any one of aspects 2-6, wherein the sending causes the user equipment to operate in DC with the MN and the base station via the candidate cell using the complete configuration.

[0239] Aspect 8. The method according to aspect 1, wherein the base station is a MN connected to a user equipment, and the user equipment operates in a DC with the MN and the SN.

[0240] Aspect 9. The method according to aspect 8, wherein the determining comprises transmitting a request to the candidate SN so that the candidate SN generates a complete configuration to configure the candidate cell.

[0241] Aspect 10. The method according to aspect 8, wherein the determining comprises: configuring a candidate SN for the conditional SN change, and transmitting a request to the candidate SN so that the candidate SN determines to configure a complete configuration for the user equipment.

[0242] Aspect 11. The method according to Aspect 9 or 10 further includes: receiving a complete configuration from a candidate SN; and sending the complete configuration and an indication of the complete configuration to a user equipment via an RRC reconfiguration message, so that the user equipment uses the complete configuration to operate in a DC with the base station and the candidate SN via the candidate cell.

[0243] Aspect 12. A method according to any one of aspects 9-11, wherein the sending further comprises providing an indication of a set of one or more conditions to be satisfied before the user equipment communicates with the candidate SN via the candidate cell using the complete configuration.

[0244] Aspect 13. A method according to aspect 12, wherein a complete configuration is sent to the user equipment so that if the user equipment detects a radio link failure (RLF) with a cell and the user equipment determines that a set of one or more conditions is met, the user equipment communicates with the candidate SN via the candidate cell.

[0245] Aspect 14. The method according to aspect 1, wherein the base station is a MN connected to the user equipment, and is further configured to hand over the user equipment to a candidate MN.

[0246] Aspect 15. The method according to aspect 14, wherein the determining comprises transmitting a request to the candidate MN so that the candidate MN generates a complete configuration to configure the candidate cell.

[0247] Aspect 16. The method according to Aspect 15 further includes: receiving a complete configuration from the candidate MN; and sending the complete configuration, an indication of the complete configuration, and an indication of a second set of one or more conditions to be met before the user equipment is handed over to the candidate MN and communicates with the candidate MN using the complete configuration.

[0248] Aspect 17. The method according to aspect 1, wherein the base station is a MN connected to the user equipment and is further configured to hand over the user equipment to the candidate cell.

[0249] Aspect 18. A method according to aspect 1 or 17, wherein the sending comprises including an indication of the complete configuration to the user equipment via an RRC reconfiguration message.

[0250] Aspect 19. A method according to aspect 1, 17 or 18, wherein the sending further comprises providing an indication of a second set of one or more conditions to be satisfied before the user equipment communicates with the base station using the full configuration.

[0251] Aspect 20. The method according to aspect 18 or 19, wherein the sending causes the user equipment to communicate with the base station via the candidate cell using the complete configuration.

[0252] Aspect 21. The method according to any one of aspects 7, 16 or 20 further comprises: after the user equipment establishes a connection with the base station via the candidate cell using the complete configuration, releasing the previously received configuration.

[0253] Aspect 22. A method in a base station, the base station being capable of providing a complete configuration associated with a radio connection to a user equipment and an incremental configuration that the user equipment can apply to a previously received first configuration, the method comprising: processing hardware and sending a second configuration to the user equipment so that the user equipment updates the first configuration according to the second configuration, thereby generating an updated first configuration; determining, by the processing hardware of the base station and while the user equipment is operating in a cell covered by the base station using the first configuration, to configure an incremental configuration for the user equipment so as to modify one or more parameters included in the updated first configuration after the user equipment communicates with the base station using the updated first configuration; identifying, by the processing hardware, at least a candidate cell for the incremental configuration; and, when the user equipment determines that a set of one or more conditions is met, sending, by the processing hardware and to the user equipment an indication of a set of one or more conditions to be met before the user equipment communicates with the base station via the candidate cell using the incremental configuration and at least a portion of the updated first configuration.

[0254] Aspect 23. The method according to aspect 22, wherein the parameters of the second configuration overlap with the parameters of the incremental configuration.

[0255] Aspect 24. A method according to Aspect 22, wherein transmitting a second configuration to a user equipment is caused by a trigger event detected by a base station, wherein the second configuration includes new configuration parameters that do not exist in the first configuration; wherein, when the base station no longer detects the trigger event, the incremental configuration causes the user equipment to release the new configuration parameters; and wherein at least a portion of the updated first configuration does not include the new configuration parameters.

[0256] Aspect 25. A method in a base station, which is capable of providing a complete configuration associated with a radio connection to a user equipment and an incremental configuration that the user equipment can apply to a previously received first configuration, the method comprising: determining, by processing hardware of the base station and while the user equipment is operating in a cell covered by the base station using the first configuration, to configure an incremental configuration for the user equipment; identifying, by the processing hardware, at least a candidate cell for the incremental configuration; and transmitting, by the processing hardware and to the user equipment, a second configuration so that the user equipment updates the first configuration according to the second configuration, thereby generating an updated first configuration, wherein the incremental configuration and the second configuration do not have overlapping configuration parameters; after sending the second configuration to the user equipment, transmitting, by the processing hardware and to the user equipment, the incremental configuration and an indication of a set of one or more conditions to be satisfied before the user equipment communicates with the base station via the candidate cell using the incremental configuration and the updated first configuration.

[0257] Aspect 26. A base station comprising hardware and configured to perform a method according to any one of aspects 1 to 25.

[0258] Aspect 27. A method in a user equipment, the user equipment being capable of receiving a complete configuration associated with a radio connection to a base station and an incremental configuration that the user equipment can apply to a first configuration previously received, the method comprising: receiving, by processing hardware of the user equipment and while the user equipment is operating in a cell covered by the base station using the first configuration, a complete configuration from the base station, the complete configuration providing information for user equipment operation within a candidate cell; determining, by the processing hardware of the user equipment, whether a set of one or more conditions associated with the complete configuration of the candidate cell are satisfied; and if the user equipment determines that the set of conditions is satisfied, using the complete configuration by the processing hardware of the user equipment to connect to the candidate cell.

[0259] Aspect 28. The method according to Aspect 27 further includes: detecting a radio link failure (RLF) with a cell; in response to the detection, determining that a set of one or more conditions associated with complete configuration of a candidate cell is satisfied; and in response to the determination, communicating via the candidate cell.

[0260] Aspect 29. A method in a user equipment, the user equipment being capable of receiving a complete configuration associated with a radio connection to a base station and an incremental configuration that the user equipment can apply to a previously received first configuration, the method comprising: while the user equipment is operating in a cell covered by the base station using the first configuration, receiving a second configuration by the processing hardware of the user equipment and from the base station, the second configuration being used to update the first configuration to generate an updated first configuration for operating in the cell covered by the base station; while the user equipment is operating in the cell, receiving a first incremental configuration by the processing hardware of the user equipment and from the base station, the first incremental configuration providing information for the operation of the user equipment within a first candidate cell to modify the updated configuration after the user equipment communicates with the base station using the updated first configuration. one or more parameters included in a first configuration of the first candidate cell; determining, by processing hardware of the user equipment, whether a first set of one or more conditions associated with the first incremental configuration of the first candidate cell is satisfied; before detecting that the set of one or more conditions associated with the first incremental configuration of the first candidate cell is satisfied: updating, by processing hardware of the user equipment, the first configuration according to the second configuration to generate an updated configuration; and communicating with a base station using the updated configuration by the processing hardware of the user equipment; and after detecting that the first set of one or more conditions associated with the first incremental configuration of the first candidate cell is satisfied, connecting to the first candidate cell using the first incremental configuration and at least a portion of the updated first configuration or one of at least a portion of the first configuration by the processing hardware of the user equipment.

[0261] Aspect 30. The method according to aspect 29, wherein if the second configuration includes a new configuration parameter that is not in the first configuration, updating the first configuration includes adding the new configuration parameter to the first configuration.

[0262] Aspect 31. The method according to aspect 29, wherein if the second configuration modifies a configuration parameter in the first configuration, updating the first configuration includes modifying the configuration parameter in the first configuration.

[0263] Aspect 32. The method according to aspect 29, wherein if the second configuration releases the configuration parameters in the first configuration, updating the first configuration includes releasing the configuration parameters in the first configuration.

[0264] Aspect 33. The method according to aspects 30-32, wherein the configuration parameters configure radio resources so that the user equipment communicates with the base station via a cell or a secondary cell.

[0265] Aspect 34. A method in a user equipment, the user equipment being capable of receiving a complete configuration associated with a radio connection to a base station and an incremental configuration that the user equipment can apply to a previously received configuration, the method comprising: while the user equipment is operating in a cell covered by the base station using the previously received configuration, receiving a first incremental configuration by the processing hardware of the user equipment and from the base station, the first incremental configuration providing information for user equipment operation within a first candidate cell, wherein the first incremental configuration is associated with a first set of one or more conditions; while the user equipment is operating in a cell covered by the base station using the previously received configuration, receiving a second incremental configuration by the processing hardware of the user equipment and from the base station, the second incremental configuration providing information for user equipment operation within a second candidate cell; detecting by the processing hardware of the user equipment that a second set of one or more conditions associated with the second incremental configuration for connecting to the second candidate cell is satisfied; and connecting to the second candidate cell using the second incremental configuration and a portion of the previously received configuration by the processing hardware of the user equipment.

[0266] Aspect 35. The method according to any one of Aspects 29-34 further includes: detecting a radio link failure (RLF) with a cell; in response to the detection, determining that a first set of one or more conditions associated with a first incremental configuration for connecting to a first candidate cell or a second set of one or more conditions associated with a second incremental configuration for connecting to a second candidate cell are satisfied; and in response to the determination, connecting to the first candidate cell or the second candidate cell.

[0267] Aspect 36. A user equipment comprising hardware and configured to perform a method according to any one of aspects 27-35.

Claims

1. A method in a base station, the base station being capable of providing a complete configuration related to a radio connection to a user equipment and an incremental configuration that the user equipment can apply to a previously received configuration, the method comprising: Determining, by the base station and while the user equipment is operating in a cell covered by the base station using a previously received configuration, to configure the complete configuration for the user equipment to connect to a candidate cell; as well as The full configuration and an indication of a set of one or more conditions associated with the full configuration for user equipment to connect to a candidate cell and to be satisfied before the user equipment communicates with the base station via the candidate cell using the full configuration are sent by the base station to the user equipment.

2. The method according to claim 1, wherein: The base station is a MN connected to the user equipment, and the user equipment operates in a DC with the MN and SN.

3. The method according to claim 2, wherein: The determining includes transmitting a request to a candidate SN so that the candidate SN generates the complete configuration to configure the candidate cell.

4. The method according to claim 2, wherein: The determination includes: Configure candidate SNs for conditional SN change, and A request is transmitted to the candidate SN, so that the candidate SN determines to configure the complete configuration for the user equipment.

5. The method according to any one of claims 3 to 4, wherein: The sending further comprises providing an indication of a second set of one or more conditions to be satisfied before the user equipment communicates with the candidate SN via the candidate cell using the complete configuration.

6. The method according to claim 5, wherein: The complete configuration is sent to the user equipment such that if the user equipment detects a radio link failure (RLF) with the cell and the user equipment determines that the second set of one or more conditions is satisfied, the user equipment communicates with the candidate SN via the candidate cell.

7. The method according to claim 1, wherein: The base station is a MN connected to the user equipment, and is further configured to hand over the user equipment to a candidate MN.

8. The method according to claim 1, wherein: The base station is a MN connected to the user equipment, and is further configured to hand over the user equipment to the candidate cell.

9. A base station comprising processing hardware and configured to perform the method according to any one of claims 1-4 and 7-8.

10. A method in a user equipment, the user equipment being capable of receiving a complete configuration related to a radio connection to a base station and an incremental configuration that the user equipment is capable of applying to a previously received first configuration, the method comprising: receiving, by the user equipment and while the user equipment is operating in a cell covered by the base station using the first configuration, from the base station a complete configuration, the complete configuration providing information for user equipment operation in a candidate cell; as well as When the user equipment determines that a set of one or more conditions associated with a complete configuration providing information for user equipment operation within a candidate cell is satisfied, connecting to the candidate cell using the complete configuration by the user equipment.

11. The method according to claim 10, further comprising: detecting a radio link failure (RLF) with the cell; responsive to the detecting, determining that a set of one or more conditions associated with the complete configuration providing information for user equipment operation within the candidate cell is satisfied; as well as In response to the determination, communicating via the candidate cell.

12. The method according to claim 10, further comprising: An indication of the detected RLF is transmitted to the base station.

13. The method according to any one of claims 10 to 12, wherein: The base station is a MN connected to the user equipment, and the user equipment operates in a DC with the MN and SN.

14. The method according to any one of claims 10 to 12, wherein: The user equipment communicates with the candidate SN via the candidate cell using the complete configuration.

15. A user equipment comprising processing hardware and configured to perform the method according to any one of claims 10-12.

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