Conditional process operation

Abstract

To configure a connection with a UE, a central unit (CU) of a distributed base station provides, by processing hardware, a conditional configuration for a cell of a distributed unit (DU) of the base station to the UE (1002). The CU receives, by the processing hardware, an identifier of the cell of the DU (1004). In addition, the CU determines, by the processing hardware, that the UE is connected to the cell based on the identifier of the cell (1006), and communicates with the UE according to the conditional configuration for the cell (1008).

Description

[0001] Cross-reference to related applications

[0002] This application claims priority and benefit to (1) U.S. Provisional Patent Application No. 63 / 008,610, entitled “Conditional Procedure Operations,” filed April 10, 2020, and (2) U.S. Provisional Patent Application No. 63 / 028,294, entitled “Conditional Procedure Operations,” filed May 21, 2020, the entire disclosure of each of which is expressly incorporated herein by reference. Technical Field

[0003] This disclosure generally relates to wireless communications, and more specifically to conditional procedures, such as conditional handover, conditional primary / secondary cell (PSCell) addition or change procedures, and conditional secondary node addition or change procedures (i.e., PSCell addition or change procedures with SN change). Background Technology

[0004] This background description is provided for the purpose of generally presenting the background of this disclosure. To the extent described in this background section, the work of the currently named inventors, and aspects of the description that may not conform to the prior art at the time of submission, are neither expressly nor implicitly acknowledged as prior art to this disclosure.

[0005] In telecommunications systems, the Packet Data Convergence Protocol (PDCP) sublayer of the radio protocol stack provides services such as user plane data transmission, encryption, and integrity protection. For example, the PDCP layer, defined for the Evolved Universal Terrestrial Radio Access (EUTRA) radio interface (see 3GPP specification TS 36.323) and New Radio (NR) (see 3GPP specification TS 38.323), provides the ordering of Protocol Data Units (PDUs) in the uplink direction (from user equipment (UE) to the base station) and the downlink direction (from the base station to the UE). Furthermore, the PDCP sublayer provides Signaling Radio Bearers (SRBs) and Data Radio Bearers (DRBs) to the Radio Resource Control (RRC) sublayer. Generally, the UE and base station can use SRBs to exchange RRC messages and Non-Access Stratum (NAS) messages, and can use DRBs to transmit data on the user plane.

[0006] UEs can use several types of SRBs and DRBs. When operating in dual connectivity (DC), the cell associated with the base station operating as the primary node (MN) defines the primary cell group (MCG), while the cell associated with the base station operating as the secondary node (SN) defines the secondary cell group (SCG). The so-called SRB1 resource carries RRC messages, which in some cases include NAS messages on the dedicated control channel (DCCH), and the SRB2 resource supports RRC messages or NAS messages including logged measurement information, which also pass through the DCCH but have a lower priority than the SRB1 resource. More generally, the SRB1 and SRB2 resources allow the UE and MN to exchange RRC messages associated with the MN, as well as embedded RRC messages associated with the SN, and can also be referred to as the MCG SRB. The SRB3 resource allows the UE and SN to exchange RRC messages associated with the SN and can also be referred to as the SCG SRB. Split SRBs allow the UE to exchange RRC messages directly with the MN via lower-layer resources of the MN and SN. Furthermore, a DRB that uses only the low-level resources of MN can be called an MCG DRB, a DRB that uses only the low-level resources of SN can be called an SCG DRB, and a DRB that uses the low-level resources of both MCG and SCG can be called a split DRB.

[0007] In some scenarios, a UE can simultaneously utilize the resources of multiple RAN nodes (e.g., components of a base station or distributed base station) interconnected via backhaul. This type of connection is called Multiple Radio Dual Connectivity (MR-DC) when these network nodes support different Radio Access Technologies (RATs). When a UE operates in an MR-DC, one base station operates as the primary node (MN) covering the primary cell (PCell), while another base station operates as the secondary node (SN) covering the primary secondary cell (PSCell). The UE communicates with the MN (via the PCell) and the SN (via the PSCell). In other scenarios, the UE utilizes the resources of one base station at a time. One base station and / or the UE determines that the UE should establish a radio connection with another base station. For example, one base station may determine to hand over the UE to a second base station and initiate a handover process.

[0008] 3GPP Technical Specifications (TS) 36.300 and 38.300 describe the procedures for handover (also known as synchronous reconfiguration) scenarios. These procedures involve message passing between RAN nodes (e.g., RRC signaling and preparation), which typically results in latency, increasing the likelihood of handover failure. Some handover procedures do not involve conditions associated with the UE and can be referred to as “instant” handover procedures. Other handover procedures involve conditions associated with the UE, and 3GPP TS 36.331v16.0.0 and 38.331v16.0.0 describe conditional handover scenarios.

[0009] 3GPP specification TS 37.340v16.1.0 describes the procedures for a UE to add or change a serial number (SN) in a DC scenario. These procedures involve message passing between radio access network (RAN) nodes (e.g., RRC signaling and preparation). This message passing typically results in latency, which in turn increases the likelihood of the SN addition or SN change procedure failing. These procedures (which do not involve conditions checked at the UE) can be referred to as “on-demand” SN addition and SN change procedures.

[0010] In both single-connectivity (SC) and DC operations, the UE can also perform a handover procedure to switch from one cell to another. Depending on the scenario, the UE can switch from a cell of a first base station to a cell of a second base station, or from a cell of a first distributed element (DU) of a base station to a cell of a second DU of the same base station. 3GPP specifications 38.401v16.0.0, 36.300v16.0.0, and 38.300v16.0.0 describe a handover procedure involving several steps (RRC signaling and preparation) between RAN nodes. RRC signaling and preparation introduce latency into the handover process, thus increasing the risk of handover failure. This procedure (which does not involve conditions checked at the UE) can be referred to as an "instantaneous" handover procedure.

[0011] Recently, "conditional" procedures (i.e., conditional SN or PSCell addition / change) have been considered for SN or PSCell addition / change. Unlike the "immediate" procedures discussed above, these procedures do not add or change the SN or PSCell, or perform a handover until the UE determines that a condition is met. As used herein, the term "condition" can refer to a single detectable state or event (e.g., a specific signal quality metric exceeding a threshold), or a logical combination of such states or events (e.g., "condition A and condition B", or "(condition A or condition B) and condition C", etc.).

[0012] To configure a conditional procedure, the RAN provides the UE with conditions and configuration (e.g., one or more random access preambles, etc.). When the conditions are met, this configuration enables the UE to communicate with the appropriate base station or via the appropriate cell to the appropriate base station. For example, for conditional addition of a base station as an SN or a candidate cell as a PSCell, the RAN provides the UE with the conditions to be met before the UE can add the base station as an SN or the candidate cell as a PSCell, and the configuration to enable the UE to communicate with the base station or PSCell after the conditions have been met.

[0013] During instantaneous handover, the RAN transmits a handover command including multiple configuration parameters to the UE, and the UE attempts to connect to the target PCell configured by the handover command. After the UE successfully connects to the RAN via the target PCell, the UE communicates with the RAN on the single target PCell using the multiple configuration parameters and one or more security keys associated with the target PCell and derived from one or more security configuration parameters in the handover command. The RAN also derives one or more security keys that are the same as those derived by the UE. After the UE successfully connects to the target PCell, the RAN communicates data with the UE using the same one or more security keys and multiple configuration parameters.

[0014] During conditional handover, the RAN may transmit a conditional handover command to the UE, including multiple configuration parameters for a candidate PCell. If the UE determines that the conditions are met, the UE attempts to connect to the candidate PCell. After the UE successfully connects to the RAN via the candidate PCell, the UE communicates with the RAN on the candidate PCell using multiple configuration parameters and one or more security keys associated with the candidate PCell and derived from one or more security configuration parameters in the conditional handover command. The RAN also derives one or more security keys that are the same as those derived by the UE. After the UE successfully connects to the candidate PCell, the RAN communicates data with the UE using the same one or more security keys and multiple configuration parameters.

[0015] During the instant PSCell addition or modification process, the RAN (i.e., MN or SN) transmits an RRC reconfiguration message including multiple configuration parameters to the UE, and the UE attempts to connect to the (target) PSCell configured by the RRC reconfiguration message. After the UE successfully connects to the SN via the PSCell, the UE communicates with the SN on the PSCell using the multiple configuration parameters and one or more security keys associated with the PSCell and derived from one or more security configuration parameters in the RRC reconfiguration message. The SN also derives one or more security keys that are the same as the one or more security keys derived by the UE. After the UE successfully connects to the PSCell, the RAN (i.e., SN) communicates data with the UE using the same one or more security keys and multiple configuration parameters.

[0016] During the conditional PSCell addition or modification process, the RAN (i.e., MN or SN) transmits an RRC reconfiguration message including multiple configuration parameters to the UE, and the UE attempts to connect to a candidate PSCell configured by the RRC reconfiguration message. After the UE successfully connects to the SN via the candidate PSCell, the UE communicates with the SN on the candidate PSCell using the multiple configuration parameters and one or more security keys associated with the candidate PSCell and derived from one or more security configuration parameters in the RRC reconfiguration message. The SN also derives one or more security keys that are the same as the security keys derived by the UE. After the UE successfully connects to the candidate PSCell, the RAN (i.e., SN) communicates data with the UE using the same security keys and multiple configuration parameters.

[0017] During each conditional process, the RAN can prepare multiple candidate cells for the UE to be operated by the candidate base station. For each prepared candidate cell, the RAN transmits an RRC message to the UE including a set of configuration parameters, and the RAN communicates with the UE according to the configuration parameters.

[0018] However, scenarios involving decomposed base station architectures (e.g., base stations comprising Distributed Units (DUs) and Central Units (CUs) may present new challenges to conditional procedure schemes. For example, a candidate base station's DU can operate on multiple candidate cells. To configure the conditional procedure, the CU prepares configuration parameters, which can differ for each of the multiple candidate cells. When a UE connects to the DU via one of the multiple candidate cells, the CU does not know which of the multiple candidate cells the UE is connecting to. Therefore, the CU cannot determine which configuration parameters to use for communication with the CU via the DU. Summary of the Invention

[0019] An example embodiment of these technologies is a method for configuring a connection with a UE in the central unit (CU) of a distributed base station. The method can be executed by processing hardware and includes providing the UE with a conditional configuration of a cell of the distributed unit (DU) of the base station, and an identifier of the cell receiving the DU. The method also includes determining that the UE is connected to the cell based on the identifier of the cell, and communicating with the UE according to the conditional configuration of the cell.

[0020] Another example embodiment of these technologies is a method for configuring a connection with a UE in a distributed unit (DU) of a distributed base station. The method can be executed by processing hardware and includes receiving a request message from a central unit (CU) of the base station for obtaining a conditional configuration for connecting to a cell of the DU, and providing the CU with the conditional configuration of the cell. The method also includes performing a random access procedure with the UE to connect the UE to the cell, and providing the CU with an identifier of the cell of the DU to indicate to the CU that the UE is connected to the cell corresponding to the conditional configuration.

[0021] Another example embodiment of these technologies is a base station that includes processing hardware and is configured to perform the methods described above. Attached Figure Description

[0022] Figure 1A This is a block diagram of an example system in which the radio access network (RAN) and user equipment can implement the techniques of this disclosure for managing conditional processes associated with secondary nodes (SNs);

[0023] Figure 1B This is a block diagram of an example base station, which includes components that can... Figure 1A The system operates through centralized units (CUs) and distributed units (DUs);

[0024] Figure 2 This is a block diagram of an example protocol stack. Figure 1A The UE communicates with the base station according to this protocol stack;

[0025] Figure 3A This is a message passing diagram of an example scenario of the technology according to this disclosure, in which the UE in dual connectivity (DC) transmits the identifier of the candidate primary and secondary cell (C-PSCell) to the central unit (CU) of the SN via the MN, and the CU determines the specific C-SN configuration to use based on the identifier of the C-PSCell;

[0026] Figure 3B This is a message passing diagram of another example scenario of the technology according to this disclosure, in which the candidate DU (C-DU) sends the identifier of the C-PSCell to the CU of the SN when it detects that the UE is connected to the C-PSCell, and the CU determines the specific C-SN configuration to use based on the identifier of the C-PSCell;

[0027] Figure 3CThis is a message passing diagram of an example scenario of the technology according to this disclosure, wherein the C-DU of the SN sends a DL Data Delivery Status message to the CU of the SN after detecting that the UE is connected to the C-PSCell, and the CU determines the use of a specific C-SN configuration based on one or more Tunnel Endpoint Identifiers (TEIDs) in the DL Data Delivery Status message.

[0028] Figure 3D This is a message passing diagram of an example scenario of the technology according to this disclosure, wherein when the C-DU of the SN detects that the UE is connected to the C-PSCell, it sends the identifier of the C-PSCell to the CU of the SN, and the CU determines the specific C-SN configuration to use based on the identifier of the C-PSCell.

[0029] Figure 3E This is a message passing diagram of an example scenario of the technology according to this disclosure, wherein the C-DU of the SN sends a UL RRC Message Transfer message to the CU of the SN after detecting that the UE is connected to the C-PSCell, and the CU determines the specific C-SN configuration to use based on the UE ID(one or more) in the UL RRC Message Transfer message;

[0030] Figure 3F This is a message passing diagram of an example scenario of the technology according to this disclosure, wherein the C-DU of the SN sends a DL data transfer status message to the CU of the SN after detecting that the UE is connected to the C-PSCell, and the CU determines the use of a specific C-SN configuration based on the TEID(one or more) of the DL data transfer status message.

[0031] Figure 4A This is a message passing diagram of an example scenario of the technology according to this disclosure, in which the UE in a single connection (SC) or DC sends the identifier of the C-PSCell to the CU of the SN via the MN, and the CU determines the specific C-SN configuration to use based on the identifier of the C-PSCell.

[0032] Figure 4B This is a message passing diagram of an example scenario of the technology according to this disclosure, wherein when the C-DU of the SN detects that the UE is connected to the C-PSCell, it sends the identifier of the C-PSCell to the CU of the SN, and the CU of the SN determines the specific C-SN configuration to use based on the identifier of the C-PSCell.

[0033] Figure 4CThis is a message passing diagram of an example scenario of the technology according to this disclosure, wherein the C-DU of the SN sends a DL data transfer status message to the CU of the SN after detecting that the UE in the SC or DC is connected to the C-PSCell, and the CU determines the specific C-SN configuration to use based on the TEID(one or more) of the DL data transfer status message.

[0034] Figure 5A This is a message passing diagram of an example scenario of the technology according to this disclosure, in which the UE in the SC or DC transmits the identifier of the C-PSCell to the CU of the SN via the MN, and the CU determines the specific C-SN configuration to use based on the identifier of the C-PSCell.

[0035] Figure 5B This is a message passing diagram of an example scenario of the technology according to this disclosure, wherein when the C-DU detects that the UE in the SC or DC is connected to the C-PSCell, it sends the identifier of the C-PSCell to the CU of the SN, and the SN determines the specific C-SN configuration to use based on the identifier of the C-PSCell.

[0036] Figure 5C This is a message passing diagram of an example scenario of the technology according to this disclosure, wherein the C-DU of the SN sends a DL data delivery status message to the CU of the SN after detecting that the UE in the SC or DC is connected to the C-PSCell, and the CU determines the specific C-SN configuration to use based on one or more TEIDs for the DL data delivery status message.

[0037] Figure 5D This is a message passing diagram of an example scenario of the technology according to this disclosure, wherein when the C-DU of the SN detects that the UE in the DC is connected to the C-PSCell, it sends the identifier of the C-PSCell to the CU of the SN, and the CU determines the specific C-SN configuration to use based on the identifier of the C-PSCell.

[0038] Figure 5E This is a message passing diagram of an example scenario of the technology according to this disclosure, wherein the C-DU of the SN sends a UL RRC message transmission message to the CU of the SN after detecting that the UE in the DC is connected to the C-PSCell, and the CU determines the use of a specific C-SN configuration based on the UE ID(s) included in the UL RRC message transmission message;

[0039] Figure 5F This is a message passing diagram of an example scenario of the technology according to this disclosure, wherein the C-DU of the SN sends a DL data transfer status message to the CU of the SN after detecting that the UE in the DC is connected to the C-PSCell, and the CU determines the specific C-SN configuration to use based on the TEID(one or more) of the DL data transfer status message.

[0040] Figure 6A This is a message passing diagram of an example scenario of the technology according to this disclosure, wherein when the C-DU of the target base station detects that the UE in the SC or DC is connected to the C-PCell, it sends the identifier of the C-PSCell to the CU of the target base station, and the CU determines the specific C-SN configuration to use based on the identifier of the C-PCell.

[0041] Figure 6B This is a message passing diagram of an example scenario of the technology according to this disclosure, wherein the C-DU of the target base station sends a DL data transfer status message to the CU of the target base station after detecting that the UE in the SC or DC is connected to the C-PCell, and the CU determines the specific C-SN configuration to use based on the TEID(one or more) of the DL data transfer status message.

[0042] Figure 7A This is a message passing diagram of an example scenario of the technology according to this disclosure, wherein when the C-DU of the target base station detects that the UE in the SC or DC is connected to the C-PCell, it sends the identifier of the C-PSCell to the CU of the target base station, and the CU determines the specific C-SN configuration to use based on the identifier of the C-PCell.

[0043] Figure 7B This is a message passing diagram of an example scenario of the technology according to this disclosure, wherein the C-DU of the target base station sends a DL data transfer status message to the CU of the target base station after detecting that the UE in the SC or DC is connected to the C-PCell, and the CU determines the specific C-SN configuration to use based on the TEID(one or more) of the DL data transfer status message.

[0044] Figure 8 This is a message passing diagram of an example scenario for inter-base station mobility according to the technology of this disclosure, wherein the C-DU of the target base station sends a DL data transfer status message to the CU of the target base station after detecting that the UE is connected to the C-PCell, and the C-CU determines the use of a specific C-MN configuration based on one or more TEIDs of the DL data transfer status message.

[0045] Figure 9 This is a message passing diagram of an example scenario for in-base station mobility according to the technology of this disclosure, wherein the C-DU of the base station sends a DL data transfer status message to the CU of the target base station after detecting that the UE is connected to the C-PCell, and the C-CU determines the use of a specific C-MN configuration based on the TEID(one or more) of the DL data transfer status message.

[0046] Figure 10This is a flowchart of an example method for preparing multiple conditional configurations for a UE and receiving a message including a cell ID from a DU or UE and determining a specific conditional configuration based on the cell ID. This method can be implemented in the base station CU of this disclosure.

[0047] Figure 11 This is a flowchart of an example method for preparing multiple conditional configurations for a UE and receiving a message including one or more UE IDs from a DU and determining a specific conditional configuration based on the IP address of the DU and at least one of the one or more UE IDs, which can be implemented in a base station CU of this disclosure;

[0048] Figure 12 This is a flowchart of an example method for preparing multiple conditional configurations for a UE and receiving user plane frames / messages from a DU and determining a specific conditional configuration based on the IP address of the DU and at least one of one or more TEIDs of the user plane frame / message, which can be implemented in a base station CU of this disclosure;

[0049] Figure 13A This is a flowchart of an example method for configuring a candidate cell for a UE and preventing the configuration of a second candidate cell for the UE to avoid conditional configuration management problems. This method can be implemented in the base station or base station CU described in this disclosure.

[0050] Figure 13B This is a flowchart of an example method for configuring a candidate cell in a first network node for a UE and preventing the configuration of a second candidate cell in the first network node for the UE to avoid conditional configuration management problems. This method can be implemented in the base station or base station CU described in this disclosure.

[0051] Figure 14 This is a flowchart of an example method for initiating conditional configuration based on whether a measurement result meets a threshold and preventing the configuration of a second candidate cell to the UE from the same candidate network node to avoid conditional configuration management problems. This method can be implemented in the base station or base station CU described in this disclosure.

[0052] Figure 15 This is a flowchart of an example method for applying conditional configuration when conditions are met and including the cell identifier in the RRC response message to assist in conditional configuration management at a candidate base station, which can be implemented in the UE of this disclosure.

[0053] Figure 16 This is a flowchart of an example method for transmitting RRC response messages and including the cell identifier in the RRC response messages to assist in conditional configuration management at candidate base stations, which can be implemented in the UE of this disclosure.

[0054] Figure 17This is a flowchart of an example method for transmitting an RRC response message to a candidate secondary base station and determining whether to include the cell identifier in the RRC response message based on the SRB. This method can be implemented in the UE of this disclosure.

[0055] Figure 18 This is a flowchart of an example method for processing conditional mobility messages for a UE, which can be implemented in the base station CU of this disclosure.

[0056] Figure 19 This is a flowchart of an example method for transmitting a message of conditional mobility for a UE, which can be implemented in a base station DU of this disclosure. Detailed Implementation

[0057] Generally, the technology disclosed herein allows a first base station to configure a UE to use multiple conditional configurations associated with multiple candidate cells of a second base station (which may be the same as or different from the first base station), and one or more conditions to be met before the UE connects to a specific candidate cell. The technology also enables the base station to determine which conditional configuration and associated security key(s)(s) to apply for communication with the UE on a specific candidate cell. The conditional process can be, for example, a conditional handover process, a conditional SN addition or change process, or a conditional PSCell addition or change process. In the following discussion, the term "CPAC" is used to refer to a conditional PSCell addition or change without SN change. The term "CSAC" is used to refer to a conditional SN addition or change.

[0058] Figure 1A An example wireless communication system 100 is depicted, in which communication devices can implement these technologies. 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 is initially connected to the base station 104.

[0059] In some scenarios, base station 104 can perform an on-the-spot SN addition to configure UE 102 to operate in a dual connectivity (DC) with base station 104 and base station 106A. Base stations 104 and 106A operate as the MN and SN of UE 102, respectively. Subsequently, when UE 102 is in a DC with MN 104 and S-SN 106A, MN 104 can perform an on-the-spot 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").

[0060] In other scenarios, base station 104 may perform a conditional SN addition procedure to first configure base station 106A as a candidate SN (C-SN) for UE 102. In this case, UE 102 may be in a single connection (SC) with base station 104, or in a DC with base station 104 and another base station 106B. In contrast to the immediate SN addition scenario discussed above, UE 102 does not immediately attempt to connect to C-SN 106A. In this scenario, base station 104 again operates as the MN, but base station 106A initially operates as a C-SN instead of an SN.

[0061] More specifically, when UE 102 receives the configuration of C-SN 106A, UE 102 does not connect to C-SN 106A until UE 102 determines that a certain condition is met (UE 102 may consider multiple conditions in some cases, but for convenience, the following discussion refers only to a single condition). When UE 102 determines that the condition has been met, UE 102 connects to candidate SN 106A, causing C-SN 106A to begin operating as SN 106A for UE 102. Therefore, when base station 106A operates as a C-SN instead of an SN, base station 106A is not yet connected to UE 102 and therefore has not yet served UE 102.

[0062] In some scenarios, the condition associated with conditional SN addition may be that the signal strength / quality detected by UE 102 on the candidate primary / secondary cell (PSCell) of C-SN 106A exceeds a certain threshold or otherwise corresponds to an acceptable measurement. For example, UE 102 determines that the condition is met when one or more measurements obtained by UE 102 on the candidate PSCell (C-PSCell) are higher than a threshold configured by MN104 or a predetermined or pre-configured threshold. When UE 102 determines that the signal strength / quality on the C-PSCell of C-SN 106A is sufficiently good (again, measured relative to one or more quantization thresholds or other quantization metrics), UE 102 can perform a random access procedure to connect to candidate SN 106A. After UE 102 successfully completes the random access procedure, base station 106A begins operating as an SN, and C-PSCell becomes the PSCell of UE 102. SN 106A can then begin communicating data with UE 102.

[0063] In various configurations of the wireless communication system 100, base station 104 can be implemented as a primary eNB (MeNB) or primary gNB (MgNB), and base station 106A or 106B can be implemented as an auxiliary gNB (SgNB) or candidate SgNB (C-SgNB). UE 102 can communicate with base station 104 and base station 106A or 106B (106A / B) via the same RAT or different RATs such as EUTRA or NR. When base station 104 is a MeNB and base station 106A is an SgNB, UE 102 can be in an EUTRA-NR DC (EN-DC) with both the MeNB and the SgNB. In this scenario, MeNB 104 can configure base station 106B as a C-SgNB for UE 102, or it can choose not to configure base station 106B as a C-SgNB for UE 102. When base station 104 is a MeNB and base station 106A is a C-SgNB for UE 102, UE 102 can be in a SC with the MeNB. In this scenario, MeNB 104 can configure base station 106B as another C-SgNB for UE 102, or it can choose not to configure base station 106B as another C-SgNB for UE 102.

[0064] In some cases, the MeNB, SeNB, or C-SgNB is implemented as an ng-eNB instead of an eNB. When base station 104 is the primary ng-eNB (Mng-eNB) and base station 106A is the SgNB, UE 102 can be in a next-generation (NG) EUTRA-NR DC (NGEN-DC) with both the Mng-eNB and the SgNB. In this scenario, MeNB 104 can configure base station 106B as the C-SgNB of UE 102, or it can choose not to. When base station 104 is the Mng-eNB and base station 106A is the C-SgNB of UE 102, UE 102 can be in a SC with the Mng-eNB. In this scenario, Mng-eNB 104 can configure base station 106B as another C-SgNB for UE 102, or it can choose not to configure base station 106B as another C-SgNB for UE 102.

[0065] When base station 104 is a MgNB and base stations 106A / B are SgNBs, UE 102 can be in an NR-NRDC (NR-DC) with both the MgNB and SgNB. In this scenario, MgNB 104 can configure base station 106B as a C-SgNB for UE 102, or it can choose not to configure base station 106B as a C-SgNB for UE 102. When base station 104 is a MgNB and base station 106A is a C-SgNB for UE 102, UE 102 can be in an SC with the MgNB. In this scenario, MgNB 104 can configure base station 106B as another C-SgNB for UE 102, or it can choose not to configure base station 106B as another C-SgNB for UE 102.

[0066] When base station 104 is a MgNB and base stations 106A / B are secondary ng-eNBs (Sng-eNBs), UE 102 can be in an NR-EUTRA DC (NE-DC) with both the MgNB and the Sng-eNB. In this scenario, MgNB 104 can configure base station 106B as a C-Sng-eNB for UE 102, or it can choose not to configure base station 106B as a C-Sng-eNB for UE 102. When base station 104 is a MgNB and base station 106A is a candidate Sng-eNB (C-Sng-eNB) for UE 102, UE 102 can be in an SC with the MgNB. In this scenario, MgNB 104 can configure base station 106B as another C-Sng-eNB for UE 102, or it can choose not to configure base station 106B as another C-Sng-eNB for UE 102.

[0067] In the scenario where UE 102 switches from base station 104 to base station 106A, base stations 104 and 106A operate as the source base station (S-BS) and target base station (T-BS), respectively. When the handover is conditional, the base stations operate as a conditional T-BS (CT-BS) or simply as a C-BS. UE 102, for example, can operate in a DC with base stations 104 and 106B before the handover, and continue operating with base stations 106A and 106B or another base station after the handover is complete. Figure 1A In the DC (not shown), base stations 104 and 106A operate as the source MN (S-MN) and target MN (T-MN), respectively, provided the handover is instantaneous. When the handover is conditional, the base stations operate as a conditional T-MN (CT-MN) or simply as a C-MN.

[0068] Base stations 104, 106A, and 106B can connect to the same core network (CN) 110, which can be an evolved packet core (EPC) 111 or a fifth-generation core (5GC) 160. Base station 104 can be implemented as an eNB supporting an S1 interface for communication with EPC 111, an ng-eNB supporting an NG interface for communication with 5GC 160, or a base station supporting an NR radio interface and an NG interface for communication with 5GC 160. Base station 106A can be implemented as an EN-DC gNB (en-gNB) with an S1 interface to EPC 111, an en-gNB not connected to EPC 111, a gNB supporting an NR radio interface and an NG interface to 5GC 160, or an ng-eNB supporting an EUTRA radio interface and an NG interface to 5GC 160. For direct message exchange in the scenarios discussed below, base stations 104, 106A, and 106B can support X2 or Xn interfaces.

[0069] Among other components, EPC 111 may include a Serving Gateway (S-GW) 112 and a Mobility Management Entity (MME) 114. Typically, the S-GW 112 is configured to transmit user plane packets related to audio calls, video calls, internet traffic, etc., while the MME 114 is configured to manage authentication, registration, paging, and other related functions. 5GC 160 includes a User Plane Function (UPF) 162 and Access and Mobility Management (AMF) 164 and / or Session Management Function (SMF) 166. Generally, the UPF 162 is configured to transmit user plane packets related to 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.

[0070] like Figure 1AAs shown, base station 104 supports cell 124, base station 106A supports cell 126A, and base station 106B supports cell 126B. Cells 124 and 126A can partially overlap, and cells 124 and 126B can also partially overlap, so that UE 102 can communicate in the DC with base station 104 (operating as MN) and base station 106A (operating as SN), and when an SN change is completed, communicate in the DC with base station 104 (operating as MN) and SN 106B. Base station 106A can also support additional cells 125A and 127A. More specifically, when UE 102 is in the DC with base station 104 and base station 106A, base station 104 operates as a MeNB, Mng-eNB, or MgNB, while base station 106A operates as an SgNB or Sng-eNB. When UE 102 is in an SC with base station 104, base station 104 operates as MeNB, Mng-eNB or MgNB, and base station 106A operates as C-SgNB or C-Sng-eNB.

[0071] Generally, 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 connect to any suitable number of base stations supporting NR cells and / or EUTRA cells. Although the examples below specifically refer to particular CN types (EPC, 5GC) and RAT types (5G NR and EUTRA), in general, the techniques disclosed herein can also be applied to other suitable radio access and / or core network technologies, such as sixth-generation (6G) radio access and / or 6G core networks or 5G NR-6G DC.

[0072] Continue to refer to Figure 1A The base station 104 includes processing hardware 130, which may include one or more general-purpose processors (e.g., central processing unit (CPU)) and computer-readable memory storing machine-readable instructions executable on the one or more general-purpose processors, and / or dedicated processing units. Figure 1A The processing hardware 130 in the example implementation includes a conditional configuration controller 132 configured to manage or control the conditional configuration techniques of this disclosure. For example, the conditional configuration controller 132 may be configured to support RRC messaging associated with immediate and conditional handover procedures, and / or support operations necessary when the base station 104 operates as an MN relative to the SN. Furthermore, in some implementations and / or scenarios, the conditional configuration controller 132 may be responsible for various implementations (for UE 102 and...) as discussed below. Figure 1A Many other UEs (not shown in the text) maintain the current conditional configuration set.

[0073] Base station 106A includes processing hardware 140, which may include one or more general-purpose processors (e.g., CPUs) and computer-readable memory storing machine-readable instructions executable on the one or more general-purpose processors, and / or dedicated processing units. Figure 1A In an example implementation, the processing hardware 140 includes a conditional configuration controller 142 configured to manage or control RRC procedures and RRC configuration. For example, the conditional configuration controller 142 may be configured to support RRC messaging associated with immediate and conditional handover procedures, and / or support necessary operations when base station 106A operates as an MN, SN, candidate MN (C-MN), and / or candidate SN (C-SN). Furthermore, in some implementations and / or scenarios, the conditional configuration controller 142 may be responsible for various implementations (for UE 102 and...) as discussed below. Figure 1A Many other UEs (not shown) maintain the current conditional configuration set. Base station 106B may include processing hardware similar to processing hardware 140 of base station 106A.

[0074] although Figure 1A The diagram shows RRC controllers 132 and 142 operating in MN and SN, respectively, but base stations can typically operate as MN, SN, candidate MN, or candidate SN in different scenarios. Therefore, MN 104, SN 106A, and SN 106B can implement a similar set of functions and support both MN and SN, conditional MN, and conditional SN operations.

[0075] UE 102 includes processing hardware 150, which may include one or more general-purpose processors (e.g., CPUs) and computer-readable memory storing machine-readable instructions executable on the one or more general-purpose processors, and / or dedicated processing units. Figure 1A The processing hardware 150 in the example implementation includes a conditional configuration controller 152 configured to manage or control RRC procedures and RRC configurations associated with conditional configuration. For example, the conditional configuration controller 152 may be configured to support RRC message passing associated with immediate and conditional handover procedures and / or secondary node addition / modification procedures, and may also be responsible for maintaining the current set of conditional configurations for UE 102 (e.g., adding, releasing, or modifying conditional configurations as needed) according to any of the implementations discussed below.

[0076] In operation, UE 102 may use radio bearers (e.g., DRB or SRB) that terminate at MN 104 or SN 106A at different times. When communicating on the radio bearer, in the uplink (from UE 102 to the base station) and / or downlink (from the base station to UE 102) directions, UE 102 may apply one or more security keys.

[0077] Figure 1B An 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 a CPU, and a non-transitory computer-readable memory storing machine-readable instructions executable on said one or more general-purpose processors, and / or dedicated 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, which is configured to manage or control one or more RRC configurations and / or RRC procedures when base station 106A operates as an SN or 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 a CPU and a non-transitory computer-readable memory storing machine-readable instructions executable on said one or more general-purpose processors, and / or dedicated processing units. In some examples, the processing hardware in the example implementation includes a MAC controller configured to manage or control one or more Media Access Control (MAC) operations or procedures (e.g., random access procedures) when the base station 106A operates as an MN, SN, or candidate SN (C-SN), and an RLC controller configured to manage or control one or more Radio Link Control (RLC) operations or procedures. The processing hardware may further include a physical layer controller configured to manage or control one or more physical layer operations or procedures.

[0078] Next, Figure 2 The radio protocol stack of UE 102, which can communicate with an eNB / ng-eNB or a gNB, is shown in a simplified manner. Each of base stations 104, 106A, or 106B can be an eNB / ng-eNB or a gNB.

[0079] EUTRA's physical layer (PHY) 202A provides a transport channel to EUTRA Media Access Control (MAC) sublayer 204A, which in turn provides a logical channel to EUTRA Radio Link Control (RLC) sublayer 206A. The EUTRA RLC sublayer then provides an RLC channel to EUTRA PDCP sublayer 208, and in some cases, to NR PDCP sublayer 210. Similarly, NR's PHY 202B provides a transport channel to NR MAC sublayer 204B, which in turn provides a logical channel to NR RLC sublayer 206B, which in turn provides an RLC channel to NR PDCP sublayer 210. In some implementations, UE 102 supports both EUTRA and NR stacks to support handover between EUTRA and NR base stations and / or DC via the EUTRA and NR interfaces. Furthermore, as... Figure 2 As shown, UE 102 can support NR PDCP 210 layering on EUTRA RLC 206A.

[0080] EUTRA PDCP sublayer 208 and NR PDCP sublayer 210 receive packets that can be referred to as Service Data Units (SDUs) (e.g., from the Internet Protocol (IP) layer, layered directly or indirectly on PDCP layers 208 or 210), and output packets that can be referred to as Protocol Data Units (PDUs) (e.g., to RLC layers 206A or 206B). For simplicity, except where the difference between SDUs and PDUs is relevant, this disclosure refers to both SDUs and PDUs as “packets”.

[0081] For example, on the control plane, EUTRA PDCP sublayer 208 and NR PDCP sublayer 210 provide SRBs to exchange Radio Resource Control (RRC) messages. On the user plane, EUTRA PDCP sublayer 208 and NR PDCP sublayer 210 provide DRBs to support data exchange.

[0082] When UE 102 operates in an EUTRA / NR DC (EN-DC) (where base station 104 operates as a MeNB and base station 106A or 106B 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. In various scenarios, the network can also provide UE 102 with a SN-terminated bearer, which uses only NR PDCP 210. The MN-terminated bearer can be an MCG bearer or a split bearer. The SN-terminated bearer can be an SCG bearer or a split 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., SRB) or a DRB.

[0083] Next, several example scenarios are discussed for the base station to initiate a conditional PSCell Addition or Change (CPAC) procedure, a conditional SN Addition or Change (CSAC) procedure, or a conditional handover procedure. Figure 3 (i.e., 3A to 3F) depicts a scenario where the base station initiates a UE's CPAC procedure, and Figure 4 (i.e., 4A to 4C) depicts a scenario where the base station initiates a UE's CSAC procedure. Figure 5 (i.e., 5A to 5F) depicts a scenario where the base station initiates a UE's CPAC or CSAC procedure. Figures 6 (i.e., 6A and 6B), and 7 (i.e., 7A and 7B) also illustrate this. Figure 8 and Figure 9 The handover scenario describes the conditional handover process initiated by the base station for the UE.

[0084] First refer to Figure 3A In scenario 300A, base station 104 operates as the MN and base station 106A operates as the SN, which includes a secondary source CU (referred to herein as S-CU 172), a secondary source DU (referred to herein as S-DU 174A), and a C-DU 174B. Initially, UE 102 (operating in the DC) communicates 302A data (e.g., uplink and / or downlink data PDUs) with MN 104 (via cell 124) according to the MN configuration, and communicates 302A data (e.g., uplink and / or downlink data PDUs) with S-CU 172 via S-DU 174A (via cell 126A) according to the source SN configuration.

[0085] At a certain point, S-CU 172 determines (304A) that it should prepare for UE 102 a conditional PSCell change to the C-PSCell (e.g., C-PSCell 125A) operated by C-DU 174B. S-CU 172 may make this determination based on, for example, one or more measurements received from UE 102 or another suitable event. In response to this determination, S-CU 172 sends a (305A) UE Context Setup Request message to C-DU 174B to obtain the C-DU configuration. Upon receiving the UE Context Setup Request message, C-DU 174B includes a first C-DU configuration in a UE Context Setup Response message for UE 102. The first C-DU configuration included in this message may include one or more configuration parameters for communication on C-PSCell 125A. C-DU 174B then sends a (307A) UE Context Setup Response message to S-CU 172. After receiving the UE context setting response message, S-CU 172 generates 308A, which includes the first C-SN configuration and the first C-DU configuration. Then, S-CU 172 sends 310A, the first C-SN configuration, to MN 104, which in turn transmits 312A, an RRC container message including the first C-SN configuration, to UE 102. Events 305A and 307A occur in... Figure 3A This is collectively referred to as UE context setup procedure 306A. Events 304A, 305A, 307A, 308A, 310A, and 312A are in... Figure 3A This is collectively referred to as CPAC Configuration Process 320A.

[0086] In some implementations, S-CU 172 may instruct C-DU 174B to generate a specific candidate cell (e.g., C-PSCell 125A or C-PSCell 127A) for which C-DU configuration is to be generated. S-CU 172 may include the identifier of the specific candidate cell in the UE context setting request message. In other implementations, C-DU 174B instructs C-DU 174B to generate a C-DU configuration for that specific candidate cell (e.g., C-PSCell 125A or C-PSCell 127A) in response to the UE context setting request message, and C-DU 174B generates a C-DU configuration for that specific candidate cell in the UE context setting response message. In such implementations, S-CU 172 may determine the association between the C-DU configuration (or the C-SN configuration including the C-DU configuration) and the identifier of the specific candidate cell. S-CU 172 may store this association for use in determining which C-DU configuration (or C-SN configuration) to use. For example, in the CPAC configuration procedure 320A, the S-CU 172 may associate the identifier of C-PSCell 125A with the first C-SN configuration (or the first C-DU configuration) upon event 308A or upon receiving the UE context setting response message 307A. The S-CU 172 may store this association for use in determining 340A.

[0087] In some implementations, S-CU 172 may generate an RRC reconfiguration message including a first C-SN configuration and send the RRC reconfiguration message 310A to MN 104. MN 104 then transmits an RRC container message 312A including the RRC reconfiguration message to UE 102. In one implementation, S-CU 172 may send an SN message 310A including the first C-SN configuration or RRC reconfiguration message (e.g., an SN Modification Required message, an RRC Transfer message, etc.) to MN 104. In some implementations, UE 102 may transmit an RRC container response message to MN 104 in response to the RRC container message. In one implementation, UE 102 transmits an RRC container response message including an RRC reconfiguration complete message. MN 104 may send an SN message including the RRC reconfiguration complete message (e.g., an SN Reconfiguration Complete message) to S-CU 172. An RRC reconfiguration complete message can be responded to by an RRC reconfiguration message. An RRC container response message can be responded to by an RRC container message.

[0088] In some implementations, S-CU 172 may perform a 322A CPAC configuration procedure with C-DU 174B, MN 104, and UE 102 to configure a second C-SN configuration for UE 102 that includes a second C-DU configuration for another C-PSCell (e.g., C-PSCell 127A operated by C-DU 174B), similar to CPAC configuration procedure 320A. In other implementations, S-CU 172 may perform a 322A CPAC configuration procedure with S-DU 174A, MN 104, and UE 102 to configure a second C-SN configuration for UE 102 that includes a second C-DU configuration for another C-PSCell (e.g., C-PSCell 127A operated by S-DU 174A), similar to CPAC configuration procedure 320A. In these implementations, S-CU 172 may perform a UE context modification procedure with S-DU 174A to obtain a second C-DU configuration, instead of performing a UE context setting procedure. During the UE context modification procedure, S-CU 172 may send a UE Context Modification Request message, similar to a UE Context Setting Request message, to S-DU 174A, and S-DU 174A responds with a UE Context Modification Response message including the second DU configuration. In these implementations, events 342A and 348A will occur between UE 102 and S-DU 174A. S-CU 172 may perform CPAC configuration procedure 322A in parallel with or after CPAC configuration procedure 320A. In some implementations, during the CPAC configuration procedure 322A, the S-CU 172 may associate the identifier of the C-PSCell 127A with the second C-SN configuration (or the second C-DU configuration) upon event 308A or upon receiving a UE context setting response message 307A (or a UE context modification response message). The S-CU 172 may store this association for use in determining 340A.

[0089] In some implementations, S-CU 172 may include a first C-CU configuration in a first C-SN configuration and a second C-CU configuration in a second C-SN configuration. The first C-CU configuration and the second C-CU configuration may have the same or different contents. In other implementations, S-CU 172 may not include a C-CU configuration in the first C-SN configuration, and S-CU 172 may not include a C-CU configuration in the second C-SN configuration. The first C-CU configuration and the second C-CU configuration may have some different parts.

[0090] Subsequently, UE 102 determines (or detects) that the condition 334A is met for connecting to C-PSCell 127A and initiates a random access procedure on C-PSCell 127A in response to this detection. For convenience, this discussion may refer to the condition or configuration in the singular, but it will be understood that multiple conditions may exist, and the RRC reconfiguration message generated by S-CU 172 may include one or more configuration parameters to specify the condition or the multiple conditions.

[0091] In response to determination 334A, UE 102 transmits an RRC reconfiguration complete message 336A, including the identifier of C-PSCell 127A, to MN 104. MN 104 then sends the RRC reconfiguration complete message 338A to S-CU 172. In some implementations, UE 102 may include the frequency information of C-PSCell 127A (e.g., absolute radio channel number and / or frequency band number) in the RRC reconfiguration message 336A. S-CU 172 determines 340A, based on the identifier of C-PSCell 127A, to use the second C-SN configuration (or the second C-DU configuration and / or the second CU configuration) as the new S-SN configuration (used as the new S-DU configuration). In one implementation, MN 104 may send an SN message 338A, including the RRC reconfiguration complete message (e.g., SN reconfiguration complete message, SN Modification Request message, or RRC transmission message), to S-CU 172. Alternatively, MN 104 obtains the identifier and optional frequency information (if included) of C-PSCell 127A from the RRC reconfiguration message, includes the identifier and frequency information (if included) of C-PSCell 127A in at least one IE, and sends an SN message (e.g., SN reconfiguration complete message, SN modification request message, or RRC transmission message) including the at least one IE to S-CU 172. In another embodiment, the RRC reconfiguration message 336A may be transparent to MN 104, allowing S-CU 172 to send one or more SN messages (e.g., SN modification request message, SN configuration update message, SN information update message, etc.) to MN 104, including the identifier and optional frequency information of C-PSCell 127A (if received by S-CU 172 or derived based on the identifier of C-PSCell 127A).

[0092] In some implementations, UE 102 may generate an RRC container message (e.g., a ULInformationTransferMRDC message) that includes an RRC reconfiguration complete message and transmit the RRC container message 336A to MN 104. MN 104 then extracts the RRC reconfiguration complete message from the RRC container message and sends the RRC reconfiguration complete message 338A to S-CU 172. In one implementation, UE 102 may include the identifier of C-PSCell 127A, and optionally frequency information, in the RRC container message. In other implementations, UE 102 may generate an RRC container response message (similar to the RRC container message described above) that includes an RRC reconfiguration complete message and transmit the RRC container response message 336A to MN 104. MN 104 then extracts the RRC reconfiguration complete message from the RRC container response message and sends the RRC reconfiguration complete message 338A to S-CU 172. In one implementation, UE 102 may include the identifier of C-PSCell 127A and, optionally, frequency information in the RRC container response message.

[0093] In response to determination 334A, UE 102 then performs random access procedure 342A via C-PSCell 127A and C-DU 174B, for example, using one or more random access configurations in the second C-DU configuration. If UE 102 successfully completes the random access procedure (e.g., successfully completes contention resolution during the random access procedure), UE 102 communicates 348A via C-PSCell 127A and C-DU 174 using the second C-DU configuration, and communicates with S-CU 172 via C-DU 174 using the second CU configuration. In some embodiments, UE 102 may disconnect from PSCell 126A to perform the random access procedure, i.e., connect to C-PSCell 127A. In other embodiments, UE 102 does not disconnect from PSCell 126A while performing the random access procedure. If C-DU 174B identifies UE 102 during the random access procedure, C-DU 174B becomes S-DU 174B and communicates with UE 102 via C-PSCell 127A 348A. After or in response to the identification of UE 102 during the random access procedure, S-DU 174B can send messages (e.g., Figure 3C The DL Data Delivery Status message in the S-CU 172 indicates that UE 102 is connected. Later, if the S-CU 172 initiates a DU (e.g., DU 174A or DU 174B) from S-DU174B to S-CU 172, Figure 3A If an instantaneous change occurs to another DU (not shown), S-CU 172 may send a second C-SN configuration (i.e., a new S-SN configuration) or a second C-DU configuration (e.g., a new S-DU configuration) to that DU. Subsequently, if S-CU 172 initiates an instantaneous SN change to base station 106B, or if MN 104 requests the latest SN configuration, S-CU 172 may send a second C-SN configuration to MN 104.

[0094] In some implementations, the random access procedure can be a four-step random access procedure or a two-step random access procedure. In a two-step random access procedure, UE 102 can transmit message A, including the UE identifier (ID), to C-DU 174B. In other implementations, the random access procedure can be a contention-based random access procedure or a contention-free random access procedure. In a contention-based random access procedure, UE 102 can transmit message 3, including the UE ID, to C-DU 174B. C-DU 174B can allocate the UE ID in a second DU configuration. The UE ID can be a Cell Radio Network Temporary Identifier (C-RNTI). In a contention-free random access procedure, UE 102 can transmit a dedicated preamble to C-DU 174B. C-DU 174B can allocate the dedicated preamble in a second DU configuration. C-DU 174B can allocate the UE ID in the second DU configuration. If C-DU 174B receives the UE ID or the dedicated preamble, C-DU 174B identifies UE 102. After UE 102 successfully completes the 342A random access procedure (e.g., successfully completes contention resolution during the random access procedure), C-PSCell 127A begins operating as PSCell 127A, and UE 102 begins operating 348A in the DC via PCell 124 and MN 104 and via PSCell 127A and SN 106A. Specifically, UE 102 communicates 348A with SN 106A via C-PSCell 127A (i.e., the new PSCell 127A) according to a second C-SN configuration.

[0095] Because S-CU 172 receives the identifier of C-PSCell 127A, S-CU 172 does not select the first C-SN configuration (or first C-DU configuration) of C-PSCell 125A. When UE 102 connects to C-DU 174B on C-PSCell 127A, S-CU 172 uses the second C-SN configuration instead of the first C-SN configuration to communicate with UE 102, thereby avoiding communication failure due to configuration mismatch.

[0096] In some implementations, the identifier of C-PSCell 127A may be a Cell Global Identifier (CGI). In other implementations, the identifier of C-PSCell 127A may be a cell identifier in a system information block broadcast on C-PSCell 127A. In still other implementations, the identifier of C-PSCell 127A may be a Physical Cell Identifier (PCI) obtained by UE 102 from a synchronization signal received by UE 102 on C-PSCell 127A. In various implementations, S-CU 172 maintains a table for mapping between CGI and PCI or another suitable identifier for a specific cell in the wireless communication system 100 for the purpose of identifying a specific C-SN configuration.

[0097] In some implementations, S-CU 172 may include at least one first security configuration parameter in the second C-SN configuration. In other implementations, S-CU 172 may send the at least one first security configuration parameter along with the first C-SN configuration at event 310A, and MN 104 may include the at least one first security configuration parameter in the RRC container message at event 312A. S-CU 172 may select from the at least one first security configuration parameter and the first security base key (e.g., K...). SN or K SN* Generate at least one first security key (or one or more security keys). For example, the one or more first security keys may include a first encryption key for encryption and decryption and / or a first integrity key for integrity protection and verification.

[0098] In other embodiments, S-CU 172 may include at least one second security configuration parameter in the second C-SN configuration. In other embodiments, S-CU 172 may send the at least one second security configuration along with the second C-SN configuration during process 322A at an event similar to event 310A, and MN 104 may include the security configuration in the RRC container message during process 322A at an event similar to event 312A. S-CU 172 may select from the at least one second security configuration parameter and the second security base key (e.g., K...). SN or K SN*The system generates at least one second security key (or one or more security keys). For example, the one or more second security keys may include a second encryption key for encryption and decryption and / or a second integrity key for integrity protection and verification. In one embodiment, S-CU 172 determines, based on the identifier of C-PSCell 127A, to generate one or more second security keys using at least one second security configuration parameter and a second security base key. In another embodiment, S-CU 172 determines, based on the identifier of C-PSCell 127A, to use one or more second security keys. UE 102 can generate one or more second security keys from at least one second security configuration parameter and a security base key (which are the same as the one or more second security keys generated by SN 106A). In one embodiment, UE 102 can generate one or more second security keys from the at least one second security configuration parameter and a security base key after event 334A or after receiving an RRC container message during CPAC procedure 322A. Therefore, UE 102 in the DC communicates with S-CU 172 348A via S-DU 174B using a second C-SN configuration and one or more second security keys. In one implementation, the first security base key and the second security base key may be the same or identical. In another implementation, the first security base key and the second security base key may be different. S-CU 172 may determine which security base key or which or which security keys based on the identifier of C-PCell 126A.

[0099] In some other implementations, if the RRC container message at event 312A (in CPAC procedure 320A or CPAC procedure 322A) does not include any security configuration parameters for UE 102 to communicate with S-CU 172 via C-DU 174B, then UE 102 in the DC communicates with S-CU 172 via S-DU 174B using a second C-SN configuration and one or more security keys, which are configured at the dual connectivity configuration (e.g., SN addition procedure) at event 302A.

[0100] In some implementations, the first C-DU configuration may include multiple configuration parameters, such as physical layer configuration parameters, MAC configuration parameters, RLC configuration parameters, and / or one or more random access configurations required for UE 102 to perform a 342A random access procedure with C-DU 174B on C-PSCell 125A (if UE 102 determines that the conditions for connecting to C-PSCell 125A are met). The second C-DU configuration may include multiple configuration parameters, such as physical layer configuration parameters, MAC configuration parameters, RLC configuration parameters, and / or one or more random access configurations required for UE 102 to perform a 342A random access procedure with C-DU 174B on C-PSCell 127A. In other implementations, the first C-DU configuration may be a CellGroupConfig information element (IE) configuring C-DU 174B for C-PSCell 125A and zero or more C-SCells. The second C-DU configuration may be a CellGroupConfig IE that configures C-PSCell 127A of C-DU 174B and zero or one or more C-SCells. In some other embodiments, the first C-DU configuration may include the configuration in ConfigPartSCG-r12IE, and the second C-DU configuration may include the configuration in ConfigPartSCG-r12IE.

[0101] In some implementations, the first C-CU configuration may include a radio bearer configuration and / or a measurement configuration. The second C-CU configuration may also include a radio bearer configuration and / or a measurement configuration. For example, the radio bearer configuration may be a RadioBearerConfig IE, a DRB-ToAddModList IE, or an SRB-ToAddModList IE, a DRB-ToAddMod IE, or an SRB-ToAddMod IE. The measurement configuration may be a MeasConfig IE.

[0102] In some implementations, the first C-SN configuration may be an RRCReconfiguration message or an RRCReconfiguration-IE conforming to 3GPP TS 38.331. The second C-SN configuration may also be an RRCReconfiguration message or an RRCReconfiguration-IE conforming to 3GPP TS 38.331. In other implementations, the first C-SN configuration may be an RRCConnectionReconfiguration message or an RRCConnectionReconfiguration-IE conforming to 3GPP TS 36.331. The second C-SN configuration may also be an RRCConnectionReconfiguration message or an RRCConnectionReconfiguration-IE conforming to 3GPP TS 36.331.

[0103] In some implementations, the MN configuration includes a RadioBearerConfig IE, an RRCReconfiguration message, an RRCReconfiguration-IE, a CellGroupConfig IE, and / or a MeasConfig IE conforming to 3GPP TS 38.331. In other implementations, the MN configuration includes an RRCConnectionReconfiguration message or an RRCConnectionReconfiguration-IE conforming to 3GPP TS 36.331. In still other implementations, the MN configuration includes configurations within a RadioBearerConfig IE, a CellGroupConfig IE, an RRCReconfiguration-IE, and / or an RRCConnectionReconfiguration-IE.

[0104] In some implementations, the S-SN configuration includes the RadioBearerConfigIE, RRCReconfiguration message, RRCReconfiguration-IE, CellGroupConfig IE, and / or MeasConfig IE conforming to 3GPP TS 38.331. In other implementations, the S-SN configuration includes the RRCConnectionReconfiguration message or RRCConnectionReconfiguration-IE conforming to 3GPP TS 36.331. In still other implementations, the S-SN configuration includes configurations within the RadioBearerConfig IE, CellGroupConfig IE, RRCReconfiguration-IE, and / or RRCConnectionReconfiguration-IE. In some implementations, the S-SN configuration may include S-DU configuration. The S-DU configuration may include multiple configuration parameters, such as physical layer configuration parameters, MAC configuration parameters, and RLC configuration parameters. The S-DU configuration may be the CellGroupConfig IE or may include configurations within the ConfigPartSCG-r12 IE.

[0105] In some implementations, if MN 104 is a gNB, the RRC container message is an RRCReconfiguration message, and the RRC container response message is an RRCReconfigurationComplete message. In other implementations, if MN 104 is an eNB or ng-eNB, the RRC container message is an RRCConnectionReconfiguration message, and the RRC container response message is an RRCConnectionReconfigurationComplete message.

[0106] In some implementations, if SN 106A is a gNB, the RRC reconfiguration message and the RRC reconfiguration completion message are respectively an RRCReconfiguration message and an RRCReconfigurationComplete message. In other implementations, if SN 106A is an eNB or ng-eNB, the RRC reconfiguration message and the RRC reconfiguration completion message are respectively an RRCConnectionReconfiguration message and an RRCConnectionReconfigurationComplete message.

[0107] Now for reference Figure 3B Scenario 300B involves CPAC without SN change (i.e., conditional change of the SN's PSCell when the UE is already in a DC with both the MN and SN). In this scenario, base station 104 operates as the MN, and base station 106A operates as the SN, which includes a secondary CU (here referred to as S-CU 172), a secondary DU (here referred to as S-DU 174A), and a C-DU 174B. Events in this scenario similar to those discussed above are labeled with the same reference numerals, and Figure 3A Examples and implementation methods can be applied to Figure 3B The following discussion... Figure 3A and Figure 3B The differences between the scenarios.

[0108] In scenario 300B, UE 102 may not transmit the RRC reconfiguration complete message 336B to MN 104, or it may transmit the 336B RRC reconfiguration complete message to MN 104 without the identifier of C-PSCell 127A. After C-DU 174B identifies UE 102 during the random access procedure at event 342B, C-DU 174B may transmit a DU-to-CU message 344B including the identifier of C-PSCell 127A to S-CU 172 to indicate that UE 102 is connected to C-PSCell 127A, so that S-CU 172 can determine 346B to use the second C-SN configuration (or the second C-DU configuration) as the new S-SN configuration (or as the new S-DU configuration) based on the identifier of C-PSCell 127A. In some implementations, the DU-to-CU message may be an F1AP message or a DL data transfer status message. For example, an F1AP message can be a UL RRC message delivery message that includes a spurious RRC message or excludes an RRC message. In another example, an F1AP message can be a new F1AP message that excludes an RRC message. In yet another example, an F1AP message can be a UL RRC message delivery message that includes an RRC container IE. C-DU 174B can include spurious or fake RRC messages (i.e., RRC messages not received from UE 102) in the RRC container IE. C-DU 174B can include an indicator indicating that the RRC container IE should be ignored (or discarded) in the UL RRC message delivery message. S-CU 172 ignores (or discards, does not use) the RRC container IE (i.e., spurious or fake RRC messages) in response to this indicator.

[0109] Because S-CU 172 receives the identifier of C-PSCell 127A, S-CU 172 does not select the first C-SN configuration (or first C-DU configuration) of C-PSCell 125A. Therefore, when UE 102 connects to C-DU 174B on C-PSCell 127A, S-CU 172 does not use the first C-SN configuration to communicate with UE 102, thereby avoiding communication failure due to configuration mismatch.

[0110] Now for reference Figure 3C Scenario 300C involves CPAC without SN change (i.e., conditional change of the SN's PSCell when the UE is already in a DC with both the MN and SN). In this scenario, base station 104 operates as the MN, and base station 106A operates as the SN, which includes a secondary CU (here referred to as S-CU 172), a secondary DU (here referred to as S-DU 174A), and a C-DU 174B. Events in this scenario similar to those discussed above are labeled with the same reference numerals, and... Figure 3A Examples and implementation methods can be applied to Figure 3C The following discussion... Figure 3C and Figures 3A-3B The differences between the scenarios.

[0111] In scenario 300C, UE 102 may not transmit the RRC reconfiguration complete message 336C to MN 104, or it may transmit the 336C RRC reconfiguration complete message to MN 104 without the identifier of C-PSCell 127A.

[0112] After C-DU 174B identifies UE 102 during the random access procedure at event 342C, C-DU 174B may send a 345C DL data delivery status message to S-CU 172. In some implementations, C-DU 174B may send a 345C General Packet Radio Service (GPRS) Tunneling Protocol (GTP) packet including the DL data delivery status message to S-CU 172. The GTP packet may include one or more Tunnel Endpoint Identifiers (TEIDs). The TEID(s) ...)(s)(s)(s)(s)(s)(s)(s)(s))(s)(s)(s)(s)(s)(s)(s))(s)(s)(s)(s)(s)(s))(s)(s)(s)(s)(s))(s)(s)(s)(s)(s))(s)(s)(s)(s))(s)(s)(s)(s))(s)(s)(s)(s))(s)(s)(s)(s))(s)(s)(s)(s))(s)(s)(s)(s))(s)(s)(s)(s))(s)(s)(s)(s))(s)(s)(s)(s))(s)(s)(s)) S-CU 172 can assign a TEID for the S-CU 172 endpoint used for transmitting the F1 transport bearer of the UL PDU in the UE context setting request message. C-DU 174B can assign a TEID for the C-DU 174B endpoint used for transmitting the F1 transport bearer of the DL PDU in the UE context setting response message in the UE context setting procedure 306C. One or more TEIDs can be the same or different values. S-CU 172 can associate one or more TEIDs with the C-DU configuration (obtained during the UE context setting procedure) and the C-CU configuration (if generated by S-CU 172) so that S-CU 172 can determine, based on one or more TEIDs received in the GTP packet, to use a specific C-SN configuration (or a specific C-DU configuration) as the new S-SN configuration (or as the new S-DU configuration). In scenario 300C, S-CU 172 can determine 346C that the second C-SN configuration (or the second C-DU configuration) will be used as the new S-SN configuration (used as the new S-DU configuration) based on one or more TEIDs received in a GTP packet including the DL data transfer status message 345C. S-CU 172 can establish or store an association between one or more specific TEIDs and specific C-SN configurations (or specific C-DU configurations included in specific C-SN configurations), such that S-CU 172 can determine the specific C-SN configuration (or the specific C-DU configuration) based on one or more specific TEIDs received in a GTP packet including the DL data transfer status message.For example, S-CU 172 can establish one or more specific TEIDs and specific C-SN configurations (or specific C-DU configurations included in the C-SN configuration) after performing a UE context setting procedure (or UE context modification procedure) with C-DU 174B (or S-DU 174A) to obtain the C-DU configuration of the candidate cell. S-CU 172 can also be configured as follows. Figure 3A The process involves associating the identifier of a specific candidate cell (e.g., C-PSCell 125A or C-PSCell 127A) with a specific C-SN configuration (or a specific C-DU configuration included within a specific C-SN configuration). Therefore, S-CU 172 can establish or store the association between the identifier of a specific candidate cell, one or more specific TEIDs, and the specific C-SN configuration (or a specific C-DU configuration included within a specific C-SN configuration). S-CU 172 can determine the identifier of a specific candidate cell based on one or more TEIDs received in GTP packets including DL data transfer status messages. S-CU 172 can send the identifier of the specific candidate cell to MN 104 as described above.

[0113] For example, during the UE context setting process in CPAC configuration 320C, S-CU 172 can assign a first TEID to the S-CU 172 endpoint for transmitting the F1 transport bearer of the UL PDU in the UE context setting request message. C-DU 174B can assign a second TEID to the C-DU 174B endpoint for transmitting the F1 transport bearer of the DL PDU in the UE context setting response message in UE context setting process 306C. The first TEID and the second TEID can be the same or different. S-CU 172 associates a first C-SN configuration (or C-DU configuration) with the first TEID and / or the second TEID. During the UE context setting process in CPAC configuration 322C, S-CU 172 can assign a third TEID to the S-CU 172 endpoint for transmitting the F1 transport bearer of the UL PDU in the UE context setting request message. C-DU 174B may assign a fourth TEID for the C-DU 174B endpoint used to transmit the F1 transport bearer of the DL PDU in the UE context setting response message during the UE context setting procedure 306C. The third TEID and the fourth TEID may be the same or different, and are different from the first TEID and the second TEID. S-CU 172 associates the first C-SN configuration (or C-DU configuration) with the third TEID and / or the fourth TEID.

[0114] C-DU 174B includes the third TEID and / or the fourth TEID in the GTP packet that includes the DL data transfer status message, and transmits the GTP packet 345C to S-CU 172. S-CU 172 can determine from the third TEID and / or the fourth TEID received from the GTP packet whether to use the second C-SN configuration (or the second C-DU configuration) as the new S-SN configuration (used as the new S-DU configuration).

[0115] Based on one or more TEIDs in the GTP packet including DL data transfer status message 345C, S-CU 172 does not select the first CU configuration of C-PSCell 125A. Therefore, when UE 102 connects to C-DU 174B on C-PSCell 127A, S-CU 172 does not use the first CU configuration of C-PSCell 125A to communicate with UE 102, thereby avoiding communication failures due to configuration mismatch.

[0116] Now for reference Figure 3D Scenario 300D involves CPAC without SN change (i.e., conditional change of the SN's PSCell when the UE is already in a DC with both the MN and SN). In this scenario, base station 104 operates as the MN, and base station 106A operates as the SN, which includes a secondary CU (here referred to as S-CU 172), a secondary DU (here referred to as S-DU 174A), and a C-DU 174B. Events in this scenario similar to those discussed above are labeled with the same reference numerals, and... Figure 3A Examples and implementation methods can be applied to Figure 3D The following discussion... Figure 3D and Figure 3A The differences between the scenarios.

[0117] The CPAC configuration process 321D is generally similar to Figure 3A The CPAC configuration process is as follows: 320A. However, in scenario 300D, S-CU 172 sends the first C-SN configuration (311D) to S-DU 174A, and S-DU 174A then transmits the first C-SN configuration (313D) to UE 102, instead of the previous process as described by S-CU 172. Figure 3AIn scenario 300A, the first C-SN configuration is transmitted to the UE 102 via MN 104. In some implementations, S-CU 172 configures the first SRB for the UE 102 via MN 104 and transmits the first C-SN configuration to the UE 102 via the first SRB via S-DU 174A. For example, SN 106A transmits the SRB configuration configuring the first SRB (e.g., SRB3) to MN 104, and MN 104 transmits the SRB configuration to the UE via a second SRB (e.g., SRB1) between MN 104 and UE 102.

[0118] In some implementations, S-CU 172 can generate an RRC reconfiguration message including a first C-SN configuration and send 311D and 313DRRC reconfiguration messages on the first SRB via S-DU 174A. In one implementation, S-CU 172 can send an F1AP message (e.g., DL RRC Message Transfer message, UE context modification request message, etc.) including the RRC reconfiguration message to S-DU 174A. In some implementations, in response to the RRC reconfiguration message, UE 102 can transmit an RRC reconfiguration complete message to S-DU 174A on the first SRB. Subsequently, S-DU 174A sends the RRC reconfiguration complete message to S-CU 172. In one implementation, S-DU 174A can send an F1AP message (e.g., UL RRC Message Transfer message, UE context modification response message, etc.) including the RRC reconfiguration complete message to S-CU 172.

[0119] In some implementations, S-CU 172 may perform a 323DCPAC configuration procedure with C-DU 174B, S-DU 174A, and UE 102 to configure UE 102 with a second C-SN configuration including a second C-DU configuration for another C-PSCell (e.g., C-PSCell 127A operated by C-DU 174B), similar to CPAC configuration procedure 321D. In other implementations, S-CU 172 may perform a 323D CPAC configuration procedure with S-DU 174A and UE 102 to configure UE 102 with a second C-SN configuration including a second C-DU configuration for another C-PSCell (e.g., C-PSCell 127A operated by S-DU 174A), similar to CPAC configuration procedure 321D. In these implementations, S-CU 172 may perform a UE context modification procedure with S-DU 174A instead of a UE context setting procedure to obtain the second C-DU configuration. During the UE context modification process, S-CU 172 may send a UE context modification request message (similar to a UE context setting request message) to S-DU 174A, and S-DU 174A responds with a UE context modification response message including the configuration of the second DU. In these implementations, events 342D and 348D will occur between UE 102 and S-DU 174A. S-CU 172 may execute CPAC configuration procedure 323D in parallel with or after CPAC configuration procedure 321D.

[0120] Subsequently, UE 102 determines (or detects) that condition 334D for connecting to C-PSCell 127A is met and, in response to this detection, initiates a random access procedure on C-PSCell 127A. For convenience, this discussion may refer to condition or configuration in the singular, but it will be understood that multiple conditions may exist, and the RRC reconfiguration message generated by S-CU 172 may include one or more configuration parameters to specify the condition or the multiple conditions.

[0121] In response to determination 334D, UE 102 then performs a random access procedure 342D via C-PSCell 127A and C-DU 174B, for example, using one or more random access configurations in a second C-DU configuration. If UE 102 successfully completes the random access procedure (e.g., successfully resolves contention during the random access procedure), UE 102 communicates 348D via C-PSCell 127A and C-DU 174B using the second C-DU configuration, and communicates with S-CU 172 via C-DU 174B using the second CU configuration. In some embodiments, UE 102 may disconnect from PSCell 126A to perform the random access procedure, i.e., connect to C-PSCell 127A. In other embodiments, UE 102 does not disconnect from PSCell 126A while performing the random access procedure. If C-DU 174B identifies UE 102 during the random access procedure, C-DU 174B becomes S-DU 174B and communicates with UE 102 via C-PSCell 127A 348D. After identifying UE 102 during the random access procedure, or in response to identifying UE 102 during the random access procedure, S-DU 174B can send messages (e.g., Figure 3C The DL data transfer status message in the S-CU 172 indicates that UE 102 is connected. Later, if S-CU 172 initiates a DU from S-DU 174B to S-CU 172 (e.g., DU174A or...), Figure 3D If an instantaneous change occurs to another DU (not shown), S-CU 172 may send a second C-SN configuration (i.e., a new S-SN configuration) or a second C-DU configuration (e.g., a new S-DU configuration) to that DU. Subsequently, if S-CU 172 initiates an instantaneous SN change to base station 106B, or if MN 104 requests the latest SN configuration, S-CU 172 may send a second C-SN configuration to MN 104.

[0122] During or after the random access procedure, UE 102 transmits a 337D RRC reconfiguration complete message to C-DU 174B, which in turn sends a 339D ULRRC message transmission message to S-CU 172, including the RRC reconfiguration complete message and the identifier of C-PSCell 127A. S-CU 172 determines, based on the identifier of C-PSCell 127A, 340D to use the second C-SN configuration (or the second C-DU configuration) as the new S-SN configuration (or as the new S-DU configuration). In one implementation, UE 102 may omit the identifier of C-PSCell 127A from the RRC reconfiguration complete message 337D.

[0123] In some implementations, the random access procedure can be a four-step random access procedure or a two-step random access procedure. In a two-step random access procedure, UE 102 may include the UE ID and RRC reconfiguration completion message 337D in message A and transmit message A to C-DU 174B. In other implementations, the random access procedure may be a contention-based random access procedure or a contention-free random access procedure. In a contention-based random access procedure, UE 102 may include the UE ID and RRC reconfiguration completion message 337D in message 3 and transmit message 3 to C-DU 174B. C-DU 174B may allocate the UE ID in the second DU configuration. The UE ID may be a C-RNTI. In a contention-free random access procedure, UE 102 may transmit a dedicated preamble to C-DU 174B. C-DU 174B may allocate the dedicated preamble in the second DU configuration. C-DU 174B may allocate the UE ID in the second DU configuration. If C-DU 174B receives the UE ID or a dedicated preamble, C-DU 174B identifies UE 102. After UE 102 successfully completes the 342D random access procedure (e.g., successfully resolves contention during the random access procedure), C-PSCell 127A begins operating as PSCell 127A, and UE 102 begins operating in the DC via PCell 124 and MN 104, and via PSCell 127A and SN 106A, for 348D. Specifically, UE 102 communicates with SN 106A via C-PSCell 127A (i.e., the new PSCell 127A) according to a second C-SN configuration for 348D.

[0124] In some implementations, prior to event 337D, UE 102 may transmit an RRC message (e.g., an RRC reconfiguration complete message, a UEAssistanceInformation message, or a ULInformationTransferMRDC message) including the identifier of C-PSCell 127A to MN 104, and MN 104 may then send the identifier of C-PSCell 127A to S-CU 172. In one implementation, MN 104 may send an SN message (e.g., an SN reconfiguration complete message, an SN modification request message, or an RRC transfer message) including the identifier of C-PSCell 127A to S-CU 172. In such an implementation, at event 339D, C-DU 174B may not include the identifier of C-PSCell 127A in the UL RRC message transfer message.

[0125] Because S-CU 172 receives the identifier of C-PSCell 127A, S-CU 172 does not select the first C-SN configuration (or first C-DU configuration) of C-PSCell 125A. Therefore, when UE 102 connects to C-DU 174B on C-PSCell 127A, S-CU 172 does not use the first C-SN configuration to communicate with UE 102, thereby avoiding communication failure due to configuration mismatch.

[0126] Now for reference Figure 3E Scenario 300E involves CPAC without SN change (i.e., conditional change of the SN's PSCell when the UE is already in a DC with both the MN and SN). In this scenario, base station 104 operates as the MN, and base station 106A operates as the SN, which includes a secondary CU (here referred to as S-CU 172), a secondary DU (here referred to as S-DU 174A), and a C-DU 174B. Events in this scenario similar to those discussed above are labeled with the same reference numerals, and... Figure 3A and Figure 3D Examples and implementation methods can be applied to Figure 3E The following discussion... Figure 3E and Figure 3A and Figure 3D The differences between the scenarios.

[0127] Unlike event 339D, at event 339E, C-DU 174B does not include the identifier of C-PSCell 127A in the ULRRC message transmission message. S-CU 172 can determine, based on one or more UE IDs included in the ULRRC message transmission message, to use a specific C-SN configuration (or a specific C-DU configuration) as the new S-SN configuration (used as the new S-DU configuration). In this scenario, S-CU 172 determines, based on one or more UE IDs included in the ULRRC message transmission message 339E, that 346E will use a second C-SN configuration (or a second C-DU configuration) as the new S-SN configuration (used as the new S-DU configuration).

[0128] In some implementations, the UE ID(s) may include one or more UE F1AP IDs, which may include at least one of CU F1AP IDs and DU F1AP IDs. S-CU 172 may include the CU F1AP ID in the UE context setting request message, and C-DU 174B may include the DU F1AP ID in the UE context setting response message. For example, S-CU 172 may include a first CU F1AP ID in the UE context setting request message in CPAC configuration procedure 321E, and a second CU F1AP ID in the UE context setting request message in CPAC configuration procedure 323E. In another example, C-DU 174B may include a first DU F1AP ID in the UE context setting response message in CPAC configuration procedure 321E, and a second DU F1AP ID in the UE context setting response message in CPAC configuration procedure 323E. Therefore, S-CU 172 can associate the first CU UE F1AP ID and / or the first DU F1AP ID with the first C-SN configuration (or the first C-DU configuration), and associate the second CU UE F1AP ID and / or the second DU F1AP ID with the second C-SN configuration (or the second C-DU configuration). After C-DU 174B identifies UE 102 during random access on C-PSCell 127A, C-DU 174B can include the second CU UE F1AP ID and / or the second DU UE F1AP ID in the UL RRC message transmission message 339E. Therefore, S-CU 172 determines that 346E uses the second C-SN configuration (or the second C-DU configuration) based on the second CU UE F1AP ID and / or the second DU UE F1AP ID in the UL RRC message transmission message 339E.

[0129] As described above, S-CU 172 can establish or store an association between one or more specific UE IDs and specific C-SN configurations (or specific C-DU configurations included in specific C-SN configurations), enabling S-CU 172 to determine a specific C-SN configuration (or specific C-DU configuration) based on one or more specific UE IDs received in the UL RRC message transmission message. For example, S-CU 172 can establish one or more specific UE IDs and specific C-SN configurations (or specific C-DU configurations included in C-SN configurations) after performing the UE context setting procedure with C-DU 174B to obtain the C-DU configuration of a candidate cell. S-CU 172 can also associate the identifier of a specific candidate cell (e.g., C-PSCell 125A or C-PSCell 127A) with a specific C-SN configuration (or a specific C-DU configuration included in a specific C-SN configuration), such as... Figure 3A Therefore, S-CU 172 can establish or store an association between a specific candidate cell identifier, one or more specific UE IDs, and a specific C-SN configuration (or a specific C-DU configuration included in a specific C-SN configuration). S-CU 172 can determine the specific candidate cell identifier based on one or more UE IDs received in a GTP packet including a DL data transfer status message. S-CU 172 can send the specific candidate cell identifier to MN 104 as described above.

[0130] In other implementations, the UE ID may include a C-RNTI. C-DU 174B may include a first C-RNTI in the UE context setting response message or the first C-DU configuration in the CPAC configuration procedure 321E, and a second C-RNTI in the UE context setting response message or the second C-DU configuration in the CPAC configuration procedure 323E. Therefore, S-CU 172 can obtain the first and second C-RNTIs from the UE context setting response message and associate the first and second RNTIs with the first C-SN configuration (or the first C-DU configuration) and the second C-SN configuration (or the second C-DU configuration), respectively. After C-DU 174B identifies UE 102 during the random access procedure on C-PSCell 127A, C-DU 174B may include the second C-RNTI in the UL RRC message transmission message 339E. Therefore, S-CU 172 determines that 346E uses the second C-SN configuration (or second C-DU configuration) based on the second C-RNTI in UL RRC message transmission message 339E.

[0131] Based on one or more UE IDs in the UL RRC message transmission, S-CU 172 does not select the first C-SN configuration (or first C-DU configuration) of C-PSCell 125A. When UE 102 connects to C-DU 174B on C-PSCell 127A, S-CU 172 does not use the first C-SN configuration to communicate with UE 102, thereby avoiding communication failures due to configuration mismatch.

[0132] Now for reference Figure 3F Scenario 300F involves CPAC without SN change (i.e., conditional change of the SN's PSCell when the UE is already in a DC with both the MN and SN). In this scenario, base station 104 operates as the MN, and base station 106A operates as the SN, which includes a secondary CU (here referred to as S-CU 172), a secondary DU (here referred to as S-DU 174A), and a C-DU 174B. Events in this scenario similar to those discussed above are labeled with the same reference numerals, and... Figure 3C and Figure 3D Examples and implementation methods can be applied to Figure 3F .

[0133] In scenario 300F, after C-DU 174B identifies UE 102 during the random access procedure at event 342F, C-DU 174B can send a 345F DL data delivery status message to S-CU 172 (similar to event 345C). Similar to event 346C, S-CU 172 determines whether a second C-SN configuration is used in 346F based on one or more TEIDs from the DL data delivery status message received at event 345F.

[0134] Next reference Figure 4A -C discusses several example scenarios involving CSAC.

[0135] First refer to Figure 4AScenario 400A involves CSAC, i.e., conditional addition of the C-PSCell of the C-SN when the UE is in an SC with the MN, or conditional change of the PSCell of the SN to the C-PSCell of the C-SN when the UE is already in a DC with the MN and the SN (e.g., base station 106B). In this scenario, base station 104 operates as the MN, and base station 106A operates as the SN, which includes both the C-CU (here referred to as C-CU 172) and the C-DU 174B. At the start of this scenario, UE 102 communicates 402A UL PDU and / or DL ​​PDU in an SC with MN 104 (via PCell 124) or in a DC with MN 104 (via PCell 124) and SN 106B (via PCell 126B). Events 406A, 408A, 434A, 436A, 438A, 440A, 442A, and 448A are similar to events 306A, 308A, 334A, 336A, 338A, 340A, 342A, and 348A. Figure 3A The descriptions, examples, and implementation methods can be applied to Figure 4A The following discussion... Figure 3A and Figure 4A The differences between the scenarios.

[0136] At a certain point, MN 104 determines 403A that it should initiate the CSAC procedure to configure base station 106A as the C-SN of UE 102. MN 104 may make this determination based on, for example, one or more measurement results received from UE 102, or based on a Conditional SN Change Required message from SN 106B, or another suitable event. In response to this determination, MN 104 sends a 404ASN Addition Request message to C-CU 172 to initiate the Conditional SN Addition procedure. In response to receiving the 404A SN Addition Request message, C-CU 172 and C-DU 174B perform a UE context setup procedure to obtain a first C-DU configuration for configuring C-PSCell (e.g., C-PSCell 125A), similar to UE context setup procedure 306A. C-CU 172 generates a 408A message containing a first C-SN configuration, including the first C-DU configuration, and includes this first C-SN configuration in an SN Addition Request Acknowledge message for UE 102. SN 106A then responds to the SN Addition Request message by sending a 410A message to MN 104. The first C-SN configuration included in this message may include one or more configuration parameters for C-PSCell 125A. Subsequently, MN 104 transmits a 412A message to UE 102 containing an RRC container message, including the first C-SN configuration. Events 403A, 404A, 406A, 408A, 410A, and 412A occur in... Figure 4A This is collectively referred to as CSAC Configuration Process 420A.

[0137] In some implementations, UE 102 may transmit an RRC container response message to MN 104 in response to an RRC container message. In one implementation, MN 104 may generate an RRC reconfiguration message including a first C-SN configuration, include the RRC reconfiguration message in the RRC container message, and send the RRC container message to UE 102 via 412A.

[0138] C-CU 172 can perform CSAC configuration procedure 422A with C-DU 174B and UE 102 to configure UE 102 with a second C-SN configuration including a second C-DU configuration for another C-PSCell (e.g., C-PSCell 127A), similar to CSAC configuration procedure 420A. C-CU 172 can perform CSAC configuration procedure 422A in parallel with CSAC configuration procedure 420A or after CSAC configuration procedure 420A.

[0139] Subsequently, UE 102 determines (or detects) that the condition 434A is met for connecting to C-PSCell 127A and initiates a random access procedure on C-PSCell 127A in response to this detection. For convenience, this discussion may refer to the condition or configuration in the singular, but it will be understood that multiple conditions may exist, and the RRC reconfiguration message generated by MN 104 may include one or more configuration parameters to specify the condition or the multiple conditions.

[0140] In response to determination 434A, UE 102 transmits an RRC reconfiguration complete message 436A, including the identifier of C-PSCell 127A, to MN 104. MN 104 then sends an RRC reconfiguration complete message 438A to C-CU 172. In some embodiments, UE 102 may include the frequency information of C-PSCell 127A (e.g., absolute radio channel number and / or frequency band number) in the RRC reconfiguration message 436A. C-CU 172 determines, based on the identifier of C-PSCell 127A, to use the second C-SN configuration (or the second C-DU configuration) as the new SN configuration (used as the new S-DU configuration). In one embodiment, MN 104 may send an SN message 438A, including the RRC reconfiguration complete message (e.g., an SN reconfiguration complete message, an SN modification request message, or an RRC transmission message), to C-CU 172. Alternatively, MN 104 obtains the identifier of C-PSCell 127A and, optionally, frequency information (if included) from the RRC reconfiguration message, includes the identifier of C-PSCell 127A and frequency information (if included) in at least one IE, and sends an SN message (e.g., SN reconfiguration complete message, SN modification request message, or RRC transmission message) including the at least one IE to C-CU 172. In another embodiment, the RRC reconfiguration message 436A may be transparent to MN 104, allowing C-CU 172 to send one or more SN messages (e.g., SN modification request message, SN configuration update message, SN information update message, etc.) to MN 104, including the identifier of C-PSCell 127A and, optionally, frequency information (if received by C-CU 172 or derived based on the identifier of C-PSCell 127A).

[0141] In some implementations, UE 102 may generate an RRC container message (e.g., a ULInformationTransferMRDC message) that includes an RRC reconfiguration complete message and transmit the RRC container message 436A to MN 104. MN 104 then extracts the RRC reconfiguration complete message from the RRC container message and sends the RRC reconfiguration complete message 438A to C-CU 172. In one implementation, UE 102 may include the identifier of C-PSCell 127A in the RRC container message and optionally include frequency information in the RRC container message. In other implementations, UE 102 may generate an RRC container response message (similar to the RRC container message described above) that includes an RRC reconfiguration complete message and transmit the RRC container response message 436A to MN 104. MN 104 then extracts the RRC reconfiguration complete message from the RRC container response message and sends the RRC reconfiguration complete message 438A to C-CU 172. In another implementation, UE 102 may include the identifier of C-PSCell 127A and, optionally, frequency information in the RRC container response message.

[0142] If C-DU 174B identifies UE 102 during the random access procedure, then C-CU 172, C-DU 174B, and C-PSCell 127A become S-CU 172, S-DU 174B, and PSCell 127A, respectively. After identifying UE 102, S-DU 174B uses the S-DU configuration to communicate with UE 102 via PSCell 127A 448A. S-DU 174B may send messages (e.g., after identifying UE 102 during the random access procedure or in response to identifying UE 102 during the random access procedure) after identifying UE 102. Figure 3C The DL data transfer status message in the S-CU 172 indicates that UE 102 is connected. Later, if S-CU 172 initiates a DU from S-DU 174B to S-CU 172 (e.g., DU 174A or...), Figure 4A If an instantaneous change occurs to another DU (not shown), S-CU 172 can send a second C-SN configuration (i.e., a new SN configuration) or a second C-DU configuration (e.g., a new S-DU configuration) to that DU. Later, if S-CU 172 initiates communication with another base station (e.g., base station 106B or...), Figure 4A If the SN of a base station (not shown) changes instantly, or if the MN 104 requests the latest SN configuration, the S-CU 172 may send the second C-SN configuration to the MN 104.

[0143] Because C-CU 172 receives the identifier from C-PSCell 127A, C-CU 172 does not select the first C-SN configuration (or first C-DU configuration) of C-PSCell 125A. Therefore, when UE 102 connects to C-DU 174B on C-PSCell 127A, C-CU 172 does not use the first C-SN configuration to communicate with UE 102, thereby avoiding communication failure due to configuration mismatch.

[0144] Now for reference Figure 4B Scenario 400B involves CSAC, i.e., conditional addition of the C-PSCell of the C-SN when the UE is in an SC with the MN, or conditional change of the PSCell of the SN to the C-PSCell of the C-SN when the UE is already in a DC with both the MN and the SN (e.g., base station 106B). In this scenario, base station 104 operates as the MN, and base station 106A operates as the SN, which includes both the C-CU (here referred to as C-CU 172) and C-DU 174B. Events similar to those discussed above in this scenario are labeled with the same reference numerals. Events 406B, 408B, 434B, 436B, 438B, 440B, 442B, 444B, and 448B are similar to events 306B, 308B, 334B, 336B, 338B, 340A, 342B, 344B, and 348B. Figure 4A and Figure 3B The descriptions, examples, and implementation methods can be applied to Figure 4B The following discussion... Figure 4B and Figure 4A The differences between the scenarios.

[0145] In scenario 400B, UE 102 may not transmit the RRC reconfiguration complete message 436B to MN 104, or it may transmit the 436B RRC reconfiguration complete message to MN 104 without the identifier of C-PSCell 127A. After C-DU 174B identifies UE 102 during the random access procedure at event 442B, C-DU 174 may transmit a 444B DU-to-CU message including the identifier of C-PSCell 127A to S-CU 172 to indicate that UE 102 is connected to C-PSCell 127A, so that S-CU 172 can determine, based on the identifier of C-PSCell 127A, to use the second C-SN configuration (or the second C-DU configuration) as the new S-SN configuration (used as the new S-DU configuration). In some implementations, the DU-to-CU message may be an F1AP message or a DL data transfer status message. For example, an F1AP message can be a UL RRC message delivery message that includes a spurious RRC message or excludes an RRC message. In another example, an F1AP message can be a new F1AP message that excludes an RRC message. In yet another example, an F1AP message can be a UL RRC message delivery message that includes an RRC container IE. C-DU 174B can include spurious or fake RRC messages (i.e., RRC messages not received from UE 102) in the RRC container IE. C-DU 174B can include an indicator indicating that the RRC container IE should be ignored (or discarded) in the UL RRC message delivery message. C-CU 172 ignores (or discards, does not use) the RRC container IE (i.e., spurious or fake RRC messages) in response to this indicator.

[0146] Since C-PSCell 127A is received, C-CU 172 does not select the first C-SN configuration (or first C-DU configuration) of C-PSCell 125A. Therefore, when UE 102 connects to C-DU 174B on C-PSCell 127A, C-CU 172 does not use the first C-SN configuration to communicate with UE 102, thereby avoiding communication failure due to configuration mismatch.

[0147] Now for reference Figure 4CScenario 400C involves CSAC, i.e., the conditional addition of the C-PSCell of the C-SN when the UE is in the SC with the MN, or the conditional change of the PSCell of the SN to the C-PSCell of the C-SN when the UE is already in the DC with both the MN and the SN (e.g., base station 106B). In this scenario, base station 104 operates as the MN, and base station 106A operates as the SN, which includes both the C-CU (here referred to as C-CU 172) and the C-DU 174B. Events similar to those discussed above in this scenario are labeled with the same reference numerals. Events 406C, 408C, 434C, 436C, 438C, 440C, 442C, 445C, and 448C are similar to events 306C, 308C, 334C, 336C, 338C, 340C, 342C, 345C, and 348C. Figure 4A and Figure 3C The descriptions, examples, and implementation methods can be applied to Figure 4C The following discussion... Figure 4C and Figure 4A The differences between the scenarios.

[0148] In scenario 400C, UE 102 may not transmit the RRC reconfiguration complete message 436C to MN 104, or it may transmit the 436C RRC reconfiguration complete message to MN 104 without the identifier of C-PSCell 127A. After C-DU 174B identifies UE 102 during the random access procedure of event 442C, C-DU 174B may send a 445C DL data delivery status message to C-CU 172. Similar to events 346C and 346F, C-CU 172 determines that 446C uses the second C-SN configuration based on one or more TEIDs of the DL data delivery status message received at event 445C.

[0149] Next reference Figures 5A-5C This section discusses several example scenarios involving CPAC or CSAC. Also refer to... Figure 5D-5F Several example scenarios involving CPAC are discussed.

[0150] First refer to Figure 5AScenario 500A involves CPAC or CSAC, where conditional addition of the C-PSCell to the C-SN occurs when the UE is in an SC with the MN, and conditional change of the PSCell from the SN to the C-PSCell of the C-SN occurs when the UE is already in a DC with both the MN and the SN (e.g., base station 106B). In this scenario, base station 106A operates as an MN including CU 172 (operating as main CU (M-CU) 172) and main DU (M-DU) 174C, and base station 106A can operate as a C-SN including CU 172 (operating as S-CU 172) and C-DU 174B. Alternatively, base station 106A can operate as an SN including CU 172 (operating as S-CU 172), C-DU 174B, and S-DU 174A.

[0151] At the start of this scenario, UE 102 is in SC with MN 106A (via PCell 126A) or in SC with MN 106A (via PCell 126A) and SN 106A (via Figure 1A The 502A UL PDU and / or DL ​​PDU are communicated in the DC of the PSCell (not shown). When the UE 102 is in the DC of MN 106A and SN 106A, events 504A, 506A, 508A, 510A, 512A, 522A, 534A, 536A, 538A, 542A and 548A are similar to events 304A, 306A, 308A, 310A, 312A, 322A, 334A, 336A, 338A, 340A, 342A and 348A. In the case that UE 102 is in the SC with MN 106A or in the DC with MN 106A and another base station (e.g., base station 106B), event 504A is similar to event 304A, and events 506A, 508A, 510A, 512A, 522A, 534A, 536A, 538A, 542A and 548A are similar to events 406A, 408A, 410A, 412A, 422A, 434A, 436A, 438A, 440A, 442A and 448A. Figure 3A and Figure 4A The descriptions, examples, and implementation methods can be applied to Figure 5A The following discussion... Figure 5A and Figure 3A and Figure 4A The differences between the scenarios.

[0152] In scenario 500A, M / S-CU 172 determines at some point (504A) that it should prepare for UE 102 a conditional PSCell change to a C-PSCell (e.g., C-PSCell 125A) operated by C-DU 174B. M / S-CU 172 may make this determination based, for example, one or more measurement results received from UE 102, a conditional SN change request message from SN 106B, or another suitable event. In response to this determination, M / S-CU 172 and C-DU 174B perform a UE context setting procedure to obtain a first C-DU configuration for configuring the C-PSCell (e.g., C-PSCell 125A), similar to UE context setting procedure 306A. The first C-DU configuration may include one or more configuration parameters for communication on C-PSCell 125A. M / S-CU 172 generates (508A) a first C-SN configuration including the first C-DU configuration. After generating the first C-SN configuration, M / S-CU 172 sends the first C-SN configuration 510A to M-DU 174C, and M-DU 174C then transmits an RRC container message including the first C-SN configuration 512A to UE 102. If UE 102 is in a DC with MN 106A and SN 106A, events 504A, 506A, 508A, 510A, and 512A can be triggered. Figure 5A This is collectively referred to as CPAC configuration procedure 520A, similar to CPAC configuration procedure 320A. If UE 102 is in an SC with MN 106A or in a DC with MN 106A and SN 106B, then events 504A, 506A, 508A, 510A, and 512A can be... Figure 5A This is collectively referred to as CSAC Configuration Procedure 520A, which is similar to CSAC Configuration Procedure 420A.

[0153] If UE 102 is in a DC with MN 106A and SN 106A, in some implementations, S-CU 172 can generate an RRC reconfiguration message including a first C-SN configuration. S-CU 172 can then include the RRC reconfiguration message in an RRC container message and send a 510A F1 Application Protocol (F1AP) message (e.g., DL RRC message delivery message, UE context modification request message, UE context setting request message, etc.) including the RRC container message to M-DU 174C. M-DU 174C then transmits a 512A RRC container message to UE 102. M-DU 174C can respond to the F1AP message (e.g., UE context modification request message, UE context setting request message, etc.) by sending an F1AP response message (e.g., UE context modification response message, UE context setting response message, etc.) to M-CU 172.

[0154] If UE 102 is in an SC with MN 106A or in a DC with MN 106A and SN 106B, in some implementations, C-CU 172 may generate an RRC reconfiguration message including a first C-SN configuration. M-CU 172 may then include the RRC reconfiguration message in an RRC container message and send a 510A F1 Application Protocol (F1AP) message (e.g., DL RRC message delivery message, UE context modification request message, UE context setting request message, etc.) including the RRC container message to M-DU 174C. Subsequently, M-DU 174C transmits a 512A RRC container message to UE 102. M-DU 174C may send an F1AP response message (e.g., UE context modification response message, UE context setting response message, etc.) to M-CU 172 in response to the F1AP message (e.g., UE context modification request message, UE context setting request message, etc.).

[0155] If UE 102 is in a DC with MN 106A and SN 106A, S-CU 172 can perform CPAC configuration procedure 522A with C-DU 174B and UE 102 to configure UE 102 with a second C-SN configuration including a second C-DU configuration for another C-PSCell (e.g., C-PSCell 127A), similar to CPAC configuration procedure 322A. S-CU 172 can perform CPAC configuration procedure 522A in parallel with or after CPAC configuration procedure 520A. In other embodiments, S-CU 172 can perform CPAC configuration procedure 522A with S-DU 174A and UE 102 to configure UE 102 with a second C-SN configuration including a second C-DU configuration for another C-PSCell (e.g., C-PSCell 127A operated by S-DU 174A), similar to CPAC configuration procedure 520A.

[0156] If UE 102 is in an SC with MN 106A or in a DC with MN 106A and SN 106B, then M-CU172 can perform CSAC configuration procedure 522A with C-DU 174B and UE 102 to configure UE 102 including a second C-SN configuration for a second C-DU configuration for another C-PSCell (e.g., C-PSCell 127A), similar to CSAC configuration procedure 422A. M-CU172 can perform CSAC configuration procedure 522A in parallel with or after CSAC configuration procedure 520A.

[0157] Subsequently, UE 102 determines (or detects) that the condition 534A is met for connecting to C-PSCell 127A and initiates a random access procedure on C-PSCell 127A in response to this detection. For convenience, this discussion may refer to the condition or configuration in the singular, but it will be understood that multiple conditions may exist, and the RRC reconfiguration message generated by CU 172 may include one or more configuration parameters to specify the condition or the multiple conditions.

[0158] In response to determination 534A, UE 102 transmits RRC reconfiguration complete message 536A, including the identifier of C-PSCell 127A, to M-DU 174C. M-DU 174C then sends RRC reconfiguration complete message 538A to M / S / C-CU 172. In some implementations, UE 102 may include the frequency information of C-PSCell 127A (e.g., absolute radio channel number and / or frequency band number) in the RRC reconfiguration message 536A. S / C-CU 172 determines 540A, based on the identifier of C-PSCell 127A, to use the second C-SN configuration (or the second C-DU configuration) as the new SN configuration (used as the new S-DU configuration).

[0159] In some implementations, UE 102 may generate an RRC container message (e.g., a ULInformationTransferMRDC message) that includes an RRC reconfiguration completion message, and transmit the RRC container message 536A to M-DU 174C, which in turn sends the RRC container message 538A to M / S / C-CU 172. In one implementation, UE 102 may include the identifier of C-PSCell 127A, and optionally frequency information, in the RRC container message. In other implementations, UE 102 may generate an RRC container response message (similar to the RRC container message described above) that includes an RRC reconfiguration completion message, and transmit the RRC container response message 536A to M-DU 174C, which in turn sends the RRC container message 538A to M / S / C-CU 172. In one implementation, UE 102 may include the identifier of C-PSCell 127A and, optionally, frequency information in the RRC container response message.

[0160] Because S / C-CU 172 receives the identifier of C-PSCell 127A, S / C-CU 172 does not select the first C-SN configuration (or first C-DU configuration) of C-PSCell 125A. Therefore, when UE 102 connects to C-DU174B on C-PSCell 127A, S / C-CU 172 does not use the first C-SN configuration of C-PSCell 125A to communicate with UE 102, thereby avoiding communication failure due to configuration mismatch.

[0161] Now for reference Figure 5BScenario 500B involves CPAC or CSAC, i.e., when the UE is in an SC with the MN, a conditional addition of the C-PSCell to the C-SN occurs; when the UE is already in a DC with both the MN and the SN (e.g., base station 106B), a conditional change occurs from the PSCell of the SN to the C-PSCell of the C-SN. In this scenario, base station 106A operates as an MN including CU 172 (operating as main CU (M-CU) 172) and main DU (M-DU) 174C, and base station 106A can operate as a C-SN including CU 172 (operating as S-CU 172) and C-DU 174B. Alternatively, base station 106A can operate as an SN including CU 172 (operating as S-CU 172), C-DU 174B, and S-DU 174A. Events similar to those discussed above in this scenario are labeled with the same reference numerals. Figure 5A and Figure 3B The descriptions, examples, and implementation methods can be applied to Figure 5B The following discussion... Figure 5B and Figure 5A The differences between the scenarios.

[0162] In scenario 500B, UE 102 may not transmit the RRC reconfiguration complete message 536B to MN 106A (i.e., to M-CU 172 via M-DU 174C), or it may transmit the 536BRRC reconfiguration complete message to MN 106A (i.e., to M-CU 172 via M-DU 174C) without the identifier of C-PSCell 127A.

[0163] After C-DU 174B identifies UE 102 during the random access procedure at event 542B, C-DU 174 can transmit a DU-CU message 544B including the identifier of C-PSCell 127A to S / C-CU 172 to indicate that UE 102 is connected to C-PSCell 127A, so that S / C-CU 172 can determine 546B to use the second C-SN configuration (or the second C-DU configuration) as the new S-SN configuration (used as the new S-DU configuration) based on the identifier of C-PSCell 127A. In some implementations, the DU-CU message can be an F1AP message or a DL data delivery status message. For example, the F1AP message can be a UL RRC message delivery message including a pseudo RRC message or excluding RRC messages. In another example, the F1AP message can be a new F1AP message excluding RRC messages. In yet another example, the F1AP message can be a UL RRC message delivery message including the RRC container IE. C-DU 174B can include pseudo-RRC messages or fake RRC messages (i.e., RRC messages not received from UE 102) in the RRC container IE. C-DU 174B can include an indicator indicating that the RRC container IE should be ignored (or discarded) in the UL RRC message delivery message. C-CU172 ignores (or discards, does not use) the RRC container IE (i.e., pseudo- or fake RRC messages) in response to this indicator.

[0164] Because S / C-CU 172 receives the identifier of C-PSCell 127A, S / C-CU 172 does not select the first C-SN configuration (or first C-DU configuration) of C-PSCell 125A. Therefore, when UE 102 connects to C-DU174B on C-PSCell 127A, S / C-CU 172 does not use the first C-SN configuration to communicate with UE 102, thereby avoiding communication failure due to configuration mismatch.

[0165] Now for reference Figure 5CScenario 500C involves CPAC or CSAC, i.e., when the UE is in an SC with the MN, a conditional addition of the C-PSCell to the C-SN occurs; when the UE is already in a DC with both the MN and the SN (e.g., base station 106B), a conditional change occurs from the PSCell of the SN to the C-PSCell of the C-SN. In this scenario, base station 106A operates as an MN including CU 172 (operating as main CU (M-CU) 172) and main DU (M-DU) 174C, and base station 106A can operate as a C-SN including CU 172 (operating as S-CU 172) and C-DU 174B. Alternatively, base station 106A can operate as an SN including CU 172 (operating as S-CU 172), C-DU 174B, and S-DU 174A. Events similar to those discussed above in this scenario are labeled with the same reference numerals. Figure 5A and Figure 3C The descriptions, examples, and implementation methods can be applied to Figure 5C The following discussion... Figure 5C and Figure 5A The differences between the scenarios.

[0166] In scenario 500C, UE 102 may not transmit the RRC reconfiguration complete message 536C to MN 106A (i.e., to M-CU 172 via M-DU 174C), or it may transmit a 536CRRC reconfiguration complete message to MN 106A (i.e., to M-CU 172 via M-DU 174C) that does not include the identifier of C-PSCell 127A. S / C-CU 172 receives a 545CDL data transfer status message from C-DU 174B and determines that 546C uses the second C-SN configuration based on one or more TEIDs of the DL data transfer status message.

[0167] Now for reference Figure 5DScenario 500D involves CPAC, i.e., the conditional addition of the C-PSCell of the SN when the UE is already in a DC with both the MN and SN. In this scenario, base station 106A operates as the MN including CU 172 (operating as the main CU (M-CU) 172) and main DU (M-DU) 174C, and base station 106A can operate as the SN including CU 172 (operating as the S-CU 172), C-DU 174B, and S-DU 174A. Events similar to those discussed above in this scenario are labeled with the same reference numerals. Events 504D, 506D, 508D, 511D, 513D, 523D, 534D, 542D, 537D, 539D, 540D, and 548D are similar to events 304D, 306D, 308D, 311D, 313D, 323D, 334D, 342D, 337D, 339D, 340D, and 348D. Figure 5A and Figure 3D The descriptions, examples, and implementation methods can be applied to Figure 5D .

[0168] Now for reference Figure 5E Scenario 500E involves CPAC, i.e., the conditional addition of the C-PSCell of the SN when the UE is already in the DC of the MN and SN. In this scenario, base station 106A operates as the MN including CU 172 (operating as the main CU (M-CU) 172) and main DU (M-DU) 174C, and base station 106A can operate as the SN including CU 172 (operating as the S-CU 172), C-DU 174B, and S-DU 174A. Events similar to those discussed above in this scenario are labeled with the same reference numerals. Events 521E, 523E, 534E, 542E, 537E, 539E, 546E, and 548E are similar to events 321E, 323E, 334E, 342E, 337E, 339E, 346E, and 348E. Figure 5A and Figure 3E The descriptions, examples, and implementation methods can be applied to Figure 5E .

[0169] Now for reference Figure 5FScenario 500F involves CPAC, i.e., the conditional addition of the C-PSCell of the SN when the UE is already in the DC of the MN and SN. In this scenario, base station 106A operates as the MN including CU 172 (operating as the main CU (M-CU) 172) and main DU (M-DU) 174C, and base station 106A can operate as the SN including CU 172 (operating as the S-CU 172), C-DU 174B, and S-DU 174A. Events similar to those discussed above in this scenario are labeled with the same reference numerals. Events 521F, 523F, 534F, 542F, 537F, 539F, 545F, and 548F are similar to events 321F, 323F, 334F, 342F, 337F, 339F, 345F, and 348F. Figure 5A and Figure 3F The descriptions, examples, and implementation methods can be applied to Figure 5F .

[0170] Figures 6A-6B , Figures 7A-7B , Figure 8 and Figure 9 The handover scenario is described, in which the base station initiates a conditional handover process for UE 102.

[0171] refer to Figure 6A In scenario 600A, base station 104 operates as an MN and base station 106A operates as a candidate base station including both candidate CU (referred to herein as C-CU 172) and candidate DU (referred to herein as C-DU 174B), and optionally another C-DU 174A. Initially, UE 102 communicates 602A data (e.g., uplink and / or downlink data PDUs) with MN 104 (via cell 124), for example, according to the S-MN configuration. Several events in scenario 600A are similar to those in scenario 300A. The following describes... Figure 3A and Figure 6A The differences between the scenarios.

[0172] At some point, MN 104 determines 604A that it should prepare UE 102 for a conditional handover to a C-PCell (e.g., C-PCell 125A) operated by C-DU 174B. MN 104 may make this determination based on, for example, one or more measurements received from UE 102 or another suitable event. In response to this determination, MN sends a 606A Handover Request message to C-CU 172. C-CU 172 and C-DU 174B perform a 608A UE context setup procedure to obtain the C-DU configuration, similar to procedure 306A in Figure 3. In some implementations, the handover request message includes a target cell ID (e.g., the CGI of C-PCell 125A), and C-CU 172 determines the C-DU based on this cell ID to perform the UE context setup procedure. C-CU 172 generates a 610A First C-MN Configuration including the obtained C-DU configuration. C-CU 172 sends a 612A handover response message to MN 104, which includes an RRC reconfiguration message containing the first C-MN configuration. MN 104 transmits a 614A RRC reconfiguration message to UE 102, which includes the C-MN configuration. Events 604A, 606A, 608A, 610A, 612A, and 614A occur in... Figure 6A This is collectively referred to as Conditional Switching (CHO) Configuration Procedure 620A.

[0173] MN 104 can perform the 622A CHO configuration procedure with C-DU 174B and UE 102 to configure a second C-MN configuration for UE 102, including a second C-DU configuration for another C-PCell (e.g., C-PCell 126A), similar to CHO configuration procedure 620A. C-CU 172 can execute CHO configuration procedures 620A and 622A in parallel or sequentially.

[0174] In some implementations, MN 104 may include a first C-CU configuration in a first C-MN configuration and a second C-CU configuration in a second C-MN configuration. The first C-CU configuration and the second C-CU configuration may have the same or different contents. In other implementations, MN 104 may not include a C-CU configuration in the first C-MN configuration, and MN 104 may not include a C-CU configuration in the second C-MN configuration. The first C-DU configuration and the second C-DU configuration may have some different parts.

[0175] Subsequently, UE 102 determines (or detects) that condition 634A for connecting to C-PCell 126A is met and initiates a random access procedure on C-PCell 126A in response to this detection. For convenience, this discussion may refer to conditions or configurations in the singular, but it will be understood that multiple conditions may exist, and conditional configurations may include one or more configuration parameters to specify the condition or the conditions. In response to this determination, UE 102 transmits a 638ARRC reconfiguration complete message to C-DU 174B, and C-DU 174B then sends a 640A UL RRC message transmission to C-CU 172, including the RRC reconfiguration complete message and the identifier of C-PCell 126A. Based on the identification of C-PCell 126A, C-CU 172 determines that 650A will use the second C-MN configuration (or the second C-DU configuration and / or the second C-CU configuration) as the new S-MN configuration (used as the new M-DU configuration and / or the new M-CU configuration).

[0176] In some implementations, the identifier of C-PCell 126A may be a Cell Global Identifier (CGI). In other implementations, the identifier of C-PCell 126A may be a cell identifier in a system information block broadcast on C-PCell 126A. In still other implementations, the identifier of C-PCell 126A may be a PCI obtained by UE 102 from a synchronization signal received by UE 102 on C-PCell 126A. In various implementations, C-CU 172 maintains a table for mapping between CGI and PCI or another suitable identifier for a specific cell in the wireless communication system 100 for the purpose of identifying a specific C-MN configuration.

[0177] In response to determination 634A, UE 102 then performs a 636A random access procedure via C-PCell 126A and C-DU 174B, for example, using one or more random access configurations in a second C-DU configuration. If UE 102 successfully completes the random access procedure, UE 102 communicates 642A via C-PCell 126A and C-DU 174B using the second C-DU configuration, and communicates with C-CU 172 via C-DU 174B using the second C-DU configuration. UE 102 may transmit a 638A RRC reconfiguration complete message during or after the random access procedure. In some embodiments, UE 102 may disconnect from PCell 124 to perform the random access procedure, i.e., connect to C-PCell 126A. In other embodiments, UE 102 does not disconnect from PCell 124 while performing the random access procedure. If C-DU 174B identifies UE 102 during the random access procedure, C-DU 174B becomes DU 174B and communicates with UE 102 via C-PCell 126A 642A. After identifying UE 102 during the random access procedure, or in response to identifying UE 102 during the random access procedure, DU 174B can send messages (e.g., Figure 3C (DL data transmission status message) to indicate to CU 172 that UE 102 is connected.

[0178] In some implementations, the random access procedure can be a four-step random access procedure or a two-step random access procedure. UE 102 can transmit the RRC reconfiguration complete message 638A in message A of the two-step random access procedure. In other implementations, the random access procedure can be a contention-based random access procedure or a contention-free random access procedure. In a contention-based random access procedure, UE 102 can transmit the RRC reconfiguration complete message 638A in message 3 of the contention-based random access procedure. In the case of a contention-free random access procedure, UE 102 can transmit the RRC reconfiguration complete message 638A after the contention-free random access procedure.

[0179] Because C-CU 172 receives C-PCell 126A in UL RRC message transmission message 640A, C-CU 172 does not select the first C-MN configuration (or the first C-DU configuration and / or the first C-CU configuration) of C-PCell 125A. Therefore, when UE102 connects to C-DU 174B on C-PCell 126A, C-CU 172 does not use the first C-MN configuration to communicate with UE102, thereby avoiding communication failure due to configuration mismatch.

[0180] In some implementations, C-CU 172 may include at least one first security configuration parameter in a second C-MN configuration. In other implementations, C-CU 172 may send the at least one first security configuration parameter along with the first C-MN configuration at event 612A, and MN 104 may forward it at event 614A. C-CU 172 may obtain the at least one first security configuration parameter and a first security base key (e.g., K...). MN or K NG-RAN* Generate at least one first security key (or one or more security keys). For example, the one or more first security keys may include a first encryption key for encryption and decryption and / or a first integrity key for integrity protection and verification.

[0181] In other embodiments, C-CU 172 may include at least one second security configuration parameter in the second C-MN configuration. In other embodiments, C-CU 172 may send the at least one second security configuration along with the second C-MN configuration during process 622A at an event similar to 612A, and MN 104 may forward it at an event similar to 614A. C-CU 172 may receive at least one second security configuration parameter and a second security base key (e.g., K...). MN or K NG-RAN*The system generates at least one second security key (or one or more security keys). For example, the one or more second security keys may include a second encryption key for encryption and decryption and / or a second integrity key for integrity protection and verification. In one embodiment, C-CU 172 determines, based on the identifier of C-PCell 126A, to generate one or more second security keys using at least one second security configuration parameter and a second security base key. In another embodiment, C-CU 172 determines, based on the identifier of C-PCell 126A, to use one or more second security keys. UE 102 can generate one or more second security keys (which are the same as the one or more second security keys generated by candidate base station 106A) based on at least one second security configuration parameter and a second security base key. In one embodiment, UE 102 may generate one or more second security keys from the at least one second security configuration parameter and the second security base key after event 634A or after receiving an RRC reconfiguration message during CHO configuration procedure 622A. Therefore, UE102 communicates with C-CU 172 via C-DU 174B 642A using a second C-MN configuration and one or more second security keys. In one embodiment, the first security base key and the second security base key may be the same or identical. In another embodiment, the first security base key and the second security base key may be different. C-CU 172 may determine which security base key or which or several security keys are based on the identifier of C-PCell 126A.

[0182] In some implementations, the first C-DU configuration may include multiple configuration parameters, such as physical layer configuration parameters, MAC configuration parameters, RLC configuration parameters, and / or one or more random access configurations required for UE 102 to perform a 636A random access procedure with C-DU 174A on C-PSCell 125A. The second C-DU configuration may include multiple configuration parameters, such as physical layer configuration parameters, MAC configuration parameters, RLC configuration parameters, and / or one or more random access configurations required for UE 102 to perform a 636A random access procedure with C-DU 174A on C-PCell 125A. In other implementations, the first C-DU configuration may be a CellGroupConfig information element (IE) configuring C-PCell 125A of C-DU 174A and zero or one or more C-SCells. The second C-DU configuration may be a CellGroupConfig IE configuring C-PCell 126A of C-DU 174B and zero or one or more C-SCells.

[0183] In some implementations, the first C-CU configuration may include a radio bearer configuration and / or a measurement configuration. The second C-CU configuration may also include a radio bearer configuration and / or a measurement configuration. For example, the radio bearer configuration may be a RadioBearerConfig IE, a DRB-ToAddModList IE, or an SRB-ToAddModList IE, a DRB-ToAddMod IE, or an SRB-ToAddMod IE. The measurement configuration may be a MeasConfig IE.

[0184] In some implementations, the first C-MN configuration may be an RRCReconfiguration message or an RRCReconfiguration-IE conforming to 3GPP TS 38.331. The second C-MN configuration may also be an RRCReconfiguration message or an RRCReconfiguration-IE conforming to 3GPP TS 38.331. In other implementations, the first C-SN configuration may be an RRCConnectionReconfiguration message or an RRCConnectionReconfiguration-IE conforming to 3GPP TS 36.331. The second C-SN configuration may also be an RRCConnectionReconfiguration message or an RRCConnectionReconfiguration-IE conforming to 3GPP TS 36.331.

[0185] In some implementations, the S-MN configuration includes RadioBearerConfigIE, RRCReconfiguration messages, RRCReconfiguration-IE, CellGroupConfig IE, and / or MeasConfig IE conforming to 3GPP TS 38.331. In other implementations, the S-MN configuration includes RRCConnectionReconfiguration messages or RRCConnectionReconfiguration-IE conforming to 3GPP TS 36.331. In still other implementations, the S-MN configuration includes configurations within RadioBearerConfig IE, CellGroupConfig IE, RRCReconfiguration-IE, and / or RRCConnectionReconfiguration-IE. In some implementations, the handover request message may be a handover request message defined in 3GPP TS 36.423 or TS 38.423, and the handover response message may be a handover request acknowledgement message defined in 3GPP TS 36.423 or TS 38.423. In some implementations, the S-MN configuration includes an M-CU configuration and / or an M-DU configuration. The M-CU configuration in some implementations is as defined for the C-CU configuration in this disclosure. The M-DU configuration in some implementations is as defined in this disclosure for the C-DU configuration of a PCell operated by an M-DU and zero or more SCells.

[0186] In some implementations, if base station 106A is a gNB, the RRC reconfiguration message and the RRC reconfiguration completion message are respectively an RRCReconfiguration message and an RRCReconfigurationComplete message. In other implementations, if SN 106A is an eNB or ng-eNB, the RRC reconfiguration message and the RRC reconfiguration completion message are respectively an RRCConnectionReconfiguration message and an RRCConnectionReconfigurationComplete message.

[0187] Next reference Figure 6BIn scenario 600B, similar to 600A, base station 104 again operates as the MN and base station 106A operates as a candidate base station, including both C-CU 172 and C-DU 174B, and optionally C-DU 174A. Several events in scenario 600B are similar to those in scenario 600A. The following describes... Figure 6B and Figure 6A The differences between the scenarios.

[0188] MN 104 can perform the 620B CHO configuration procedure with C-DU 174B and UE 102 to configure UE 102 including a first C-MN configuration for a first C-DU configuration for a first C-DU configuration for a C-PCell (e.g., C-PCell 125A), similar to CHO configuration procedure 620A. MN 104 can also perform another 622B CHO configuration procedure with C-DU 174B and UE 102 to configure UE 102 including a second C-MN configuration for a second C-DU configuration for a second C-DU configuration for a second C-DU configuration for a second C-PCell (e.g., C-PCell 126A), similar to CHO configuration procedure 620A. MN 104 can execute CHO configuration procedures 620B and 622B in parallel or sequentially.

[0189] Subsequently, UE 102 determines (or detects) that the conditions for connecting to C-PCell 126A (634B) are met and initiates a random access procedure on C-PCell 126A in response to this detection. In response to this determination, UE 102 transmits a 638B RRC reconfiguration complete message to C-DU 174B, which in turn sends a 640B UL RRC message transmission including the RRC reconfiguration complete message to C-CU 172. C-CU 172 determines, based on one or more UE IDs in the UL RRC message transmission, that 646B will use the second C-MN configuration (or the second C-DU configuration and / or the second C-CU configuration) as the new S-MN configuration (used as the new M-DU configuration and / or the new M-CU configuration). In some implementations, the UE ID(s) are gNB-CU UE F1AP ID and gNB-DU UE F1AP ID as defined in 3GPP TS 38.401 or TS 38.473.

[0190] Based on one or more UE IDs in UL RRC message transmission message 640B, C-CU 172 does not select the first C-MN configuration (or first C-DU configuration and / or first C-CU configuration) of C-PCell 125A. Therefore, when UE 102 connects to C-DU 174B on C-PCell 126A, C-CU 172 does not use the first C-MN configuration of C-PCell 125A to communicate with UE 102, thereby avoiding communication failure due to configuration mismatch.

[0191] Next reference Figure 7A In scenario 700A, base station 106A operates as a (primary) base station, which includes CU 172, a source DU (here referred to as S-DU 174A), a candidate DU (here referred to as C-DU 174B), and optionally another C-DU 174C. Initially, UE 102 communicates 702A data (e.g., uplink and / or downlink data PDUs) with CU 172 via S-DU 174A and PCell 125A, for example, according to the S-MN configuration. Several events in scenario 700A are similar to those in scenario 600A. The following describes... Figure 7A and Figure 6A The differences between the scenarios.

[0192] At a certain point, CU 172 determines (704A) that it should prepare UE 102 for a conditional handover to a C-PCell (e.g., C-PCell 126A) operated by C-DU 174C. CU 172 may make this determination based on, for example, one or more measurements received from UE 102 or another suitable event. In response to this determination, CU 172 and C-DU 174C perform the UE context setting procedure (708A) to obtain the C-DU configuration, similar to procedure 306A in Figure 3. CU 172 generates (710A) a first C-MN configuration including the obtained C-DU configuration. CU 172 sends (712A) a DL RRC message transmission message including an RRC reconfiguration message containing the first C-MN configuration. S-DU 174A transmits the received RRC reconfiguration message (714A) to UE 102. Events 704A, 708A, 710A, 712A, and 714A are in Figure 7A The configuration process is collectively referred to as Conditional Handover (CHO) for intra-base station handover, or 720A.

[0193] CU 172 can perform the 722A CHO configuration procedure with C-DU 174C and UE 102 to configure a second C-MN configuration for UE 102, including a second C-DU configuration for another C-PCell (e.g., C-PCell 127A), similar to the CHO configuration procedure 720A. CU 172 can execute the CHO configuration procedures 720A and 722A in parallel or sequentially.

[0194] In some implementations, CU 172 may include a first C-CU configuration in a first C-MN configuration and a second C-CU configuration in a second C-MN configuration. The first C-CU configuration and the second C-CU configuration may have the same or different contents. In other implementations, CU 172 may not include a C-CU configuration in the first C-MN configuration, and CU 172 may not include a C-CU configuration in the second C-MN configuration. The first C-DU configuration and the second C-DU configuration may have some different parts.

[0195] Subsequently, UE 102 determines (or detects) that condition 734A for connecting to C-PCell 127A is met and initiates a random access procedure on C-PCell 127A in response to this detection. For convenience, this discussion may refer to conditions or configurations in the singular, but it will be understood that multiple conditions may exist, and conditional configurations may include one or more configuration parameters to specify the condition or the multiple conditions. In response to this determination, UE 102 transmits a 738ARRC reconfiguration complete message to C-DU 174C, which in turn sends a 740A ULRRC message transmission to CU 172 including the RRC reconfiguration complete message and the identifier of C-PCell 127A. Based on the identifier of C-PCell 127A, CU 172 determines 750A to use the second C-MN configuration (or the second C-DU configuration and / or the second C-CU configuration) as the new S-MN configuration (used as the new M-DU configuration and / or the new M-CU configuration).

[0196] In response to determination 734A, UE 102 then, for example, performs a random access procedure 736A via C-PCell 127A and C-DU 174C using one or more random access configurations in the second C-DU configuration. If UE 102 successfully completes the random access procedure, UE 102 communicates 742A via C-PCell 127A and C-DU 174C using the second C-DU configuration, and communicates with CU 172 via C-DU 174C using the second C-DU configuration. UE 102 may transmit a 738ARRC reconfiguration complete message during or after the random access procedure. In a contention-based random access procedure, UE 102 may transmit the RRC reconfiguration complete message 738A in message 3 of the contention-based random access procedure. In the case of a contention-free random access procedure, UE 102 may transmit the RRC reconfiguration complete message 738A after the contention-free random access procedure. In some implementations, UE 102 may disconnect from PCell 125A to perform a random access procedure, i.e., connect to C-PCell 127A. In other implementations, UE 102 does not disconnect from PCell 125A during the random access procedure. If C-DU 174C identifies UE 102 during the random access procedure, C-DU 174C becomes DU 174C and communicates with UE 102 via C-PCell 127A 742A. After or in response to identifying UE 102 during the random access procedure, DU 174C may send a message (e.g., Figure 3C (DL data transmission status message) to indicate to CU 172 that UE 102 is connected.

[0197] In some implementations, the random access procedure can be a four-step random access procedure or a two-step random access procedure. In a two-step random access procedure, UE 102 may include the UE ID and RRC reconfiguration completion message 738A in message A and transmit message A to C-DU 174C. In other implementations, the random access procedure may be a contention-based random access procedure or a contention-free random access procedure. In a contention-based random access procedure, UE 102 may include the UE ID and RRC reconfiguration completion message 738A in message 3 and transmit message 3 to C-DU 174C. C-DU 174C may allocate a UE ID in a second DU configuration. The UE ID may be a C-RNTI. In a contention-free random access procedure, UE 102 may transmit a dedicated preamble to C-DU 174C. C-DU 174C may allocate a dedicated preamble in a second DU configuration. C-DU 174C may allocate a UE ID in a second DU configuration. If the C-DU 174C receives the UE ID or a special preamble, the C-DU 174C identifies UE 102.

[0198] Based on the identifier of C-PCell 127A in UL RRC message transmission message 740A, CU 172 does not select the first C-MN configuration of C-PCell 126A. Therefore, when UE 102 connects to C-DU 174C on C-PCell 127A, C-CU 172 does not use the first C-MN configuration to communicate with UE 102, thereby avoiding communication failure due to configuration mismatch.

[0199] In some implementations, CU 172 may include at least one first security configuration parameter in the second C-MN configuration. In other implementations, CU 172 may send the at least one first security configuration parameter along with the first C-MN configuration at event 712A, and S-DU 174A may forward it at event 714A. CU 172 may obtain the at least one first security configuration parameter and a security base key (e.g., K...). MN or K NG-RAN* Generate at least one first security key (or one or more security keys). For example, the one or more first security keys may include a first encryption key for encryption and decryption and / or a first integrity key for integrity protection and verification.

[0200] In other embodiments, CU 172 may include at least one second security configuration parameter in the second C-MN configuration. In other embodiments, CU 172 may send the at least one second security configuration along with the second C-MN configuration during process 722A at an event similar to event 712A, and S-DU 174A may forward it at an event similar to event 714A. CU 172 may obtain the at least one second security configuration parameter and a security base key (e.g., K...). MN or K NG-RAN* The system generates at least one security key (one or more security keys). For example, one or more second security keys may include a second encryption key for encryption and decryption and / or a second integrity key for integrity protection and verification. In one embodiment, CU 172 determines, based on the identifier of C-PCell 127A, to generate one or more security keys using at least one second security configuration parameter and a security base key. In another embodiment, CU 172 determines, based on the identifier of C-PCell 127A, to use one or more second security keys. UE 102 can generate one or more second security keys (which are the same as one or more second security keys generated by CU 172) from at least one second security configuration parameter and a security base key. In one embodiment, UE 102 may generate one or more second security keys from at least one second security configuration parameter and a security base key after receiving an RRC reconfiguration message at an event after event 734A or during event 722A. Therefore, UE 102 communicates with CU 172 via C-DU 174C 742A using a second C-MN configuration and one or more second security keys.

[0201] In some implementations, the first C-DU configuration may include multiple configuration parameters, such as physical layer configuration parameters, MAC configuration parameters, RLC configuration parameters, and / or one or more random access configurations required for UE 102 to perform a 736A random access procedure with C-DU 174B on C-PCell 126A. The second C-DU configuration may include multiple configuration parameters, such as physical layer configuration parameters, MAC configuration parameters, RLC configuration parameters, and / or one or more random access configurations required for UE 102 to perform a 736A random access procedure with C-DU 174C on C-PCell 127A. In other implementations, the first C-DU configuration may be a CellGroupConfig information element (IE) configuring C-PCell 126A of C-DU 174B and zero or one or more C-SCells. The second C-DU configuration may be a CellGroupConfig IE configuring C-PCell 127A of C-DU 174C and zero or one or more C-SCells.

[0202] In some implementations, the first C-CU configuration may include a radio bearer configuration and / or a measurement configuration. The second C-CU configuration may also include a radio bearer configuration and / or a measurement configuration. For example, the radio bearer configuration may be a RadioBearerConfig IE, a DRB-ToAddModList IE, or an SRB-ToAddModList IE, a DRB-ToAddMod IE, or an SRB-ToAddMod IE. The measurement configuration may be a MeasConfig IE.

[0203] In some implementations, the first C-MN configuration may be an RRCReconfiguration message or an RRCReconfiguration-IE conforming to 3GPP TS 38.331. The second C-MN configuration may also be an RRCReconfiguration message or an RRCReconfiguration-IE conforming to 3GPP TS 38.331. In other implementations, the first C-SN configuration may be an RRCConnectionReconfiguration message or an RRCConnectionReconfiguration-IE conforming to 3GPP TS 36.331. The second C-SN configuration may also be an RRCConnectionReconfiguration message or an RRCConnectionReconfiguration-IE conforming to 3GPP TS 36.331. In some implementations, if base station 106A is a gNB, the RRC reconfiguration and RRC reconfiguration completion messages are respectively an RRCReconfiguration message and an RRCReconfigurationComplete message. In other implementations, if SN 106A is an eNB or ng-eNB, the RRC reconfiguration and RRC reconfiguration completion messages are the RRCConnectionReconfiguration message and the RRCConnectionReconfigurationComplete message, respectively.

[0204] Next reference Figure 7B In scenario 700B, similar to 700A, base station 106A operates as the (primary) base station, which includes CU 172, S-DU 174A, C-DU 174B, and optionally another C-DU 174C. Several events in scenario 700B are similar to those in scenario 700A. The following describes... Figure 7B and Figure 7A The differences between the scenarios.

[0205] CU 172 can perform the 720B CHO configuration procedure with C-DU 174C and UE 102 to configure UE 102 including a first C-MN configuration for a first C-DU configuration for a first C-DU configuration (e.g., C-PCell 126A), similar to CHO configuration procedure 720A. CU 172 can also perform another CHO configuration procedure 722B with C-DU 174C and UE 102 to configure UE 102 including a second C-MN configuration for a second C-DU configuration for a second C-DU configuration (e.g., C-PCell 127A), similar to CHO configuration procedure 720A. CU 172 can execute CHO configuration procedures 720B and 722B in parallel or sequentially.

[0206] Subsequently, UE 102 determines (or detects) that the conditions for connecting to C-PCell 127A (734B) are met and initiates a random access procedure on C-PCell 127A in response to this detection. In response to this determination, UE 102 transmits a 738B RRC reconfiguration complete message to C-DU 174C, which in turn sends a 740B ULRRC message transmission including the RRC reconfiguration complete message to CU 172. CU 172 determines (746B) to use the second C-MN configuration (or the second C-DU configuration and / or the second C-CU configuration) as the new S-MN configuration (used as the new M-DU configuration and / or the new M-CU configuration) based on the UE ID(s) in the ULRRC message transmission. In some implementations, the UE ID(s) are the gNB-CU UE F1AP ID and gNB-DU UE F1AP ID as defined in 3GPP TS 38.401 or TS 38.473.

[0207] Based on one or more UE IDs in the UL RRC message transmission message 740B, CU 172 does not select the first C-MN configuration of C-PCell126A. Therefore, when UE 102 connects to C-DU 174C on C-PCell127A, CU 172 does not use the first C-MN configuration to communicate with UE 102, thereby avoiding communication failures due to configuration mismatch.

[0208] refer to Figure 8 In some cases, candidate base station 106B can manage conditional configuration based on one or more tunnel endpoint IDs (TEIDs) in the DL data transmission status frame during inter-base station conditional handover.

[0209] Figure 8Example scenario 800 involves a conditional handover process between base stations. In scenario 800, base station 104 operates as the MN (or source base station), and base station 106A operates as a candidate base station consisting of C-CU 172 and C-DU 174A and C-DU 174B. Several events in scenario 800 are similar to those in scenario 600A. The following describes... Figure 8 and Figure 6A The differences between the scenarios.

[0210] Initially, UE 102 communicates with MN 104 802 and uses the S-MN configuration to communicate data (e.g., UL data PDU and / or DL ​​data PDU). MN 104 can determine 804 that it should initiate a conditional handover to C-PCell (e.g., C-PCell 125A, in response to one or more measurements received from UE 102 or based on measurements of signals received from UE 102). MN 104 can make this determination to perform the conditional handover based on one or more measurements received from the UE (e.g., if the one or more measurements are higher than a first threshold). MN 104 can make this determination to perform the conditional handover based on one or more measurements received from the UE (e.g., if the one or more measurements are higher than a first threshold or a second threshold). The second threshold may be different from the first threshold.

[0211] In response to the determination of event 804, MN 104 transmits a handover request message 806 to C-CU 172, including the target cell ID (e.g., the CGI of C-PCell 125A) and security information. C-CU 172 and C-DU 174B perform the UE context setup procedure 808 to obtain the C-DU configuration of C-PCell, similar to procedure 306A in Figure 3. In some implementations, C-CU 172 determines the C-DU based on the cell ID and performs the UE context setup procedure. C-CU 172 generates a first C-MN configuration 810 including the first C-DU configuration. In response to event 806, C-CU 172 transmits a handover response message 812 including an RRC reconfiguration message, which further includes the first C-MN configuration. MN 104 then transmits the RRC reconfiguration message 814 to UE 102. Events 804, 806, 808, 810, 812, and 814 in Figure 8This is collectively referred to as the CHO configuration procedure 820. In some implementations, the handover request message is a handover request message with conditional operation indication as defined in 3GPP TS 38.423 or TS 36.423, and the handover response message is a handover request confirmation message as defined in 3GPP TS 38.423 or TS 36.423. In some implementations, the UE context setting procedure is as defined in 3GPP TS 38.401 and TS 38.473.

[0212] Later, MN 104 can determine to configure UE 102 822 using another CHO configuration procedure in order to configure a second C-MN configuration for another C-PCell (e.g., C-PCell 126A) operated by C-DU174B, similar to procedure 820. MN104 can execute CHO configuration procedures 820 and 822 in parallel or sequentially.

[0213] Subsequently, UE 102 determines (or detects) 834 that the conditions for connecting to C-PSCell 126A are met and, in response to this detection, initiates a random access procedure on C-PSCell 126A. In response to determination 834, UE 102 then performs a random access procedure 836 with C-DU 174B via C-PCell 126A, for example, using one or more random access configurations included in the second C-MN configuration. Once C-DU 174B detects that UE 102 has successfully RACH accessed one or more corresponding data radio bearers, C-DU 174B sends an 837 DL data transfer status frame to C-CU 172. Based on the TEID(s) of the DL data transfer status frame, C-CU 172 determines 850 that the second C-MN configuration (or the second C-DU configuration and / or the second C-CU configuration) will be used as the new S-MN configuration (used as the new M-DU configuration and / or the new M-CU configuration). UE 102 transmits an 838RRC reconfiguration complete message to C-DU 174B. C-DU 174B transmits an 840RRC reconfiguration complete message to C-CU 172 in a UL RRC message transmission message. UE 102 may transmit the 838RRC reconfiguration complete message during or after the random access procedure. In a contention-based random access procedure, UE 102 may transmit the RRC reconfiguration complete message 838 in message 3 of the contention-based random access procedure. In a contention-free random access procedure, UE 102 may transmit the RRC reconfiguration complete message 838 after the contention-free random access procedure. The UE communicates 842 with C-CU 172 via C-DU 174B through C-PCell 126A according to the configuration in the second C-MN configuration. In some implementations, UE 102 disconnects from the PCell hosted by MN 104 in order to access the C-PCell.

[0214] Based on one or more TEIDs in DL data transfer status frame 837, C-CU 172 does not select the first C-MN configuration of C-PCell 125A. Therefore, when UE 102 connects to C-DU 174C on C-PCell 126A, C-CU 172 does not use the first C-MN configuration to communicate with UE 102, thereby avoiding communication failures due to configuration mismatch.

[0215] In some implementations, C-CU 172 may include at least one first security configuration parameter in the second C-MN configuration. In other implementations, C-CU 172 may send the at least one first security configuration parameter along with the first C-MN configuration at event 812, and MN 104 may forward it at event 814. C-CU 172 may obtain the at least one first security configuration parameter and a security base key (e.g., K...). MN or K NG-RAN* Generate at least one first security key (or one or more security keys). For example, the one or more first security keys may include a first encryption key for encryption and decryption and / or a first integrity key for integrity protection and verification.

[0216] In other embodiments, C-CU 172 may include at least one second security configuration parameter in the second C-MN configuration. In other embodiments, C-CU 172 may send the at least one second security configuration along with the second C-MN configuration during process 822 at an event similar to event 812, and MN 104 may forward it at an event similar to event 814. C-CU 172 may receive at least one second security configuration parameter and a security base key (e.g., K...). NG-RAN* The system generates at least one security key (one or more security keys). For example, one or more second security keys may include a second encryption key for encryption and decryption and / or a second integrity key for integrity protection and verification. In one embodiment, C-CU 172 determines, based on the identifier of C-PCell 126A, to generate one or more security keys using at least one second security configuration parameter and a security base key. In another embodiment, C-CU 172 determines, based on the identifier of C-PCell 126A, to use one or more second security keys. UE 102 can generate one or more second security keys from at least one second security configuration parameter and a security base key (which are the same as one or more second security keys generated by C-CU 172). In one embodiment, UE 102 can generate one or more second security keys from the at least one second security configuration parameter and a security base key after event 834 or after receiving an RRC reconfiguration message during procedure 822. Therefore, UE 102 communicates with C-CU 172 via C-DU 174B using the second C-MN configuration and one or more second security keys 842.

[0217] In some implementations, TEID is defined as in 3GPP TS 29.281 for the General Packet Radio System (GPRS) Tunneling Protocol User Plane (GTPv1-U). In some implementations, the DL data transfer status frame is defined as in 3GPP TS 38.425, and the transmission of this frame is defined as in 3GPP TS 38.401 and TS 38.470. In some implementations, the UL RRC message transmission message is defined as in 3GPP TS 38.473.

[0218] Now for reference Figure 9 In some cases, base station 106A can manage security configuration based on one or more TEIDs used in DL data transmission status frames for in-base station conditional handover.

[0219] Figure 9 Example scenario 900 involves a conditional handover process within a base station. In scenario 900, similar to 700A, base station 106A operates as the (primary) base station, which includes CU 172, S-DU 174A, C-DU 174B, and another C-DU 174C. Several events in scenario 900 are similar to those in scenarios 700A and 800. The following describes... Figure 9 , Figure 7A and Figure 8 The differences between the scenarios.

[0220] Initially, UE 102 communicates with CU 172 via S-DU 174A on PCell 125A 902, and uses S-MN configuration to communicate data (e.g., UL data PDU and / or DL ​​data PDU). CU 172 can determine 904 that it should initiate a conditional handover to C-PCell (e.g., C-PCell 126A, in response to one or more measurements received from UE 102 or based on measurements of signals received from UE 102). CU 172 can make this determination to perform the conditional handover based on one or more measurements received from the UE (e.g., if the one or more measurements are higher than a first threshold). CU 172 can make this determination to perform the conditional handover based on one or more measurements received from the UE (e.g., if the one or more measurements are higher than a first threshold or a second threshold). The second threshold may be different from the first threshold.

[0221] In response to the determination of event 904, CU 172 and C-DU 174C perform UE context setting procedure 908 to obtain C-DU configuration, similar to procedure 306A in Figure 3. CU 172 generates 910 a first C-MN configuration including the first C-DU configuration. CU 172 transmits 912 a DL RRC message transmission message including an RRC reconfiguration message to S-DU 174A, which further includes the first C-MN configuration. S-DU 174A then transmits the RRC reconfiguration message 914 to UE 102. Events 904, 908, 910, 912, and 914 occur in... Figure 9 This is collectively referred to as the CHO configuration process 920 for intra-base station handover.

[0222] CU 172 can later determine to configure UE 102 922 using another CHO configuration procedure in order to configure a second C-MN configuration for another C-PCell (e.g., C-PCell 127A) operated by C-DU174C, similar to event 920. CU172 can execute CHO configuration procedures 920 and 922 in parallel or sequentially.

[0223] UE 102 then determines 934 that the conditions for connecting to C-PCell 127A are met and initiates a random access procedure on C-PCell 127A. UE 102 then performs a 936 random access procedure with C-DU 174C via C-PCell 127A, for example, using one or more random access configurations included in the second C-MN configuration. Once C-DU 174C detects successful RACH access by UE 102 to one or more corresponding data radio bearers, C-DU 174C sends a 937 DL data transfer status frame to CU 172, similar to event 345C. Based on the TEIDs of one or more DL data transfer status frames, CU 172 determines 950 that the second C-MN configuration (or the second C-DU configuration and / or the second C-CU configuration) will be used as the new S-MN configuration (used as the new M-DU configuration and / or the new M-CU configuration), similar to event 346C. UE 102 transmits a 938RRC reconfiguration complete message to C-DU 174C. C-DU 174C transmits a 940RRC reconfiguration complete message to CU 172 in a UL RRC message transmission message. UE 102 may transmit the 938RRC reconfiguration complete message during or after the random access procedure. In a contention-based random access procedure, UE 102 may transmit the RRC reconfiguration complete message 938 in message 3 of the contention-based random access procedure. UE 102 may include its UE ID in message 3. In a contention-free random access procedure, UE 102 may transmit the RRC reconfiguration complete message 938 after the contention-free random access procedure. UE 102 communicates with CU 172 via C-DU 174C via C-PCell 127A according to the configuration in the second C-MN configuration 942. In some implementations, UE 102 disconnects from PCell 125A hosted by S-DU 174A in order to access C-PCell. In other implementations, UE 102 continues to communicate with PCell 125A hosted by S-DU174A while performing a random access procedure on C-PCell 127A.

[0224] Based on one or more TEIDs in DL data transfer status frame 937, CU 172 does not select the first C-MN configuration of C-PCell 126A. Therefore, when UE 102 connects to C-DU 174C on C-PCell 127A, CU 172 does not use the first C-MN configuration to communicate with UE 102, thereby avoiding communication failures due to configuration mismatch.

[0225] In some implementations, CU 172 may include at least one first security configuration parameter in the second C-MN configuration. In other implementations, CU 172 may send the at least one first security configuration parameter along with the first C-MN configuration at event 912, and S-DU 174A may forward it at event 914. CU 172 may obtain the at least one first security configuration parameter and a security base key (e.g., K...). MN or K NG-RAN* Generate at least one first security key (or one or more security keys). For example, the one or more first security keys may include a first encryption key for encryption and decryption and / or a first integrity key for integrity protection and verification.

[0226] In other embodiments, CU 172 may include at least one second security configuration parameter in the second C-MN configuration. In other embodiments, CU 172 may send the at least one second security configuration along with the second C-MN configuration during process 922 at an event similar to event 912, and S-DU 174A may forward it at an event similar to event 914. CU 172 may receive at least one second security configuration parameter and a security base key (e.g., K...). NG-RAN* The system generates at least one security key (one or more security keys). For example, one or more second security keys may include a second encryption key for encryption and decryption and / or a second integrity key for integrity protection and verification. In one embodiment, CU 172 determines, based on the identifier of C-PCell127A, to generate one or more security keys using at least one second security configuration parameter and a security base key. In another embodiment, CU 172 determines, based on the identifier of C-PCell127A, to use one or more second security keys. UE 102 can generate one or more second security keys (identical to one or more second security keys generated by CU 172) from at least one second security configuration parameter and a security base key. In one embodiment, UE 102 may generate one or more second security keys from the at least one second security configuration parameter and a security base key after event 934 or after receiving an RRC reconfiguration message during procedure 922. Therefore, UE 102 communicates with CU 172 via C-DU 174C using the second C-MN configuration and one or more second security keys 942.

[0227] In some implementations, TEID is defined as in 3GPP TS 29.281 for the General Packet Radio System (GPRS) Tunneling Protocol User Plane (GTPv1-U). In some implementations, the DL data transfer status frame is defined as in 3GPP TS 38.425 for the NR user plane protocol, and the transmission of this frame is as defined in 3GPP TS 38.401 and TS 38.470. In some implementations, DL RRC message transmission and UL RRC message transmission messages are defined as in 3GPP TS 38.473.

[0228] Next, refer to Figure 10-17 This paper discusses several example methods that base stations, base station CUs, or UEs can implement to support conditional configuration processing and management in conditional mobility scenarios.

[0229] First refer to Figure 10 An example method 1000 is described for determining the use of a specific conditional configuration based on a received cell ID associated with the conditional mobility of a UE (e.g., UE 102). This method can be implemented, for example, at a base station 106A (such as...). Figure 3A , Figure 3B , Figure 3D auxiliary base stations Figure 4A and Figure 4B Target auxiliary base station Figure 5A , Figure 5B , Figure 5D and Figure 7A (Source) base station and Figure 6A This is implemented in candidate base stations. In various implementations, the cell ID mentioned is the cell global ID (CGI), and the base station or base station CU maintains a table for mapping between the CGI and the physical cell ID (PCI, for example, as specified in 3GPP TS 36.423 or 38.423) or another suitable identifier for a specific cell in the wireless communication system 100 for the purpose of managing conditional configuration.

[0230] Method 1000 begins at block 1002, where the base station CU transmits multiple conditional configurations of the UE. In block 1004, the base station CU receives data from the DU (…). Figure 3B Event 344B; Figure 3D Event 339D; Figure 4B Event 444B; Figure 5B Event 544B; Figure 5D Event 539D; Figure 6A Event 640A; Figure 7A Event 740A) or UE ( Figure 3A Event 338A; Figure 4A Event 438A; Figure 5AEvent 538A) receives a message including the cell ID. In box 1006, the base station CU determines the specific conditional configuration to use based on the received cell ID. Figure 3A Event 340A; Figure 3B Event 346B; Figure 3D Event 340D; Figure 4A Event 440A; Figure 4B Event 446B; Figure 5A Event 540A; Figure 5B Event 546B; Figure 5D Event 540D; Figure 6A Event 650A; Figure 7A Event 750A). As described above, this determination can be made based on the mapping table of cell ID and PCI maintained by the base station CU. In block 1008, the base station CU communicates with the UE via the DU on the cell using a specific conditional configuration ( Figure 3A Event 348A; Figure 3B Event 348B; Figure 3D Event 348D; Figure 4A Event 448A; Figure 4B Event 448B; Figure 5A Event 548A; Figure 5B Event 548B; Figure 5D Event 548D; Figure 6A Event 642A; Figure 7A Event 742A).

[0231] Figure 11 The illustration depicts an example method 1100 for determining a specific conditional configuration based on one or more UE IDs and / or DU IP addresses in messages from a DU related to the conditional mobility of a UE such as UE 102. This method can be implemented, for example, at a base station 106A (such as...). Figure 3E auxiliary base stations Figure 5E and Figure 7B (Source) base station and Figure 6B The UE ID is implemented in the candidate base station. In some implementations, the UE ID(s) are gNB-CU UE F1AP ID and gNB-DU UE F1AP ID as defined in 3GPP TS 38.401 or TS 38.473.

[0232] Method 1100 begins at block 1102, where the base station CU transmits multiple conditional configurations of the UE. In block 1104, the base station CU receives a message from the DU including one or more UE IDs. Figure 3E Event 339E; Figure 5E Event 539E; Figure 6BEvent 640B; Figure 7B Event 740B). In box 1106, the base station CU determines the use of a specific conditional configuration based on the IP address of the DU and at least one of the UE ID(s). Figure 3E Event 346E; Figure 5E Event 546E; Figure 6B Event 646B; Figure 7B Event 746B). In box 1108, the base station CU uses this specific conditional configuration to communicate with the UE via the DU on the cell ( Figure 3E Event 348E; Figure 5E Event 548E; Figure 6B Event 642B; Figure 7B Event 742B).

[0233] Figure 12 The illustration depicts an example method 1200 for determining a specific conditional configuration based on one or more TEIDs and / or the IP address of the DU in messages from the DU relating to the conditional mobility of a UE such as UE 102. This method can be implemented, for example, at a base station 106A (such as...). Figure 3C and Figure 3F auxiliary base stations Figure 4C Target auxiliary base station Figure 5C , Figure 5F and Figure 9 (Source) base station and Figure 8 The TEID is implemented in candidate base stations. In some implementations, it is defined as in 3GPP TS 29.281 for the General Packet Radio System (GPRS) Tunneling Protocol User Plane (GTPv1-U).

[0234] Method 1200 begins at block 1202, where the base station CU transmits multiple conditional configurations of the UE. In block 1204, the base station CU receives user plane frames / messages from the DU. Figure 3C Event 345C; Figure 3F Event 345F; Figure 4C Event 445C; Figure 5C Event 545C; Figure 5F Event 545F; Figure 8 Event 837; Figure 9 Event 937). In box 1206, the base station determines the use of a specific conditional configuration based on the DU's IP address and at least one of the TEIDs (one or more) of the user plane frame / message. Figure 3C Event 346C; Figure 3F Event 346F; Figure 4C Event 446C; Figure 5C Event 546C; Figure 5F Event 546F; Figure 8 Event 850; Figure 9 Event 950). In box 1208, the base station CU uses this specific conditional configuration to communicate with the UE via the DU on the cell ( Figure 3C Event 348C; Figure 3F Event 348F; Figure 4C Event 448C; Figure 5C Event 548C; Figure 5F Event 548F; Figure 8 Event 842; Figure 9 (Event 942).

[0235] Figure 13A The illustration depicts an example method 1300A for configuring conditional configurations (e.g., C-MN configuration, C-SN configuration, or C-DU configuration) for a UE and avoiding the need to manage multiple conditional configurations. This method can be implemented, for example, at a first network node (such as...). Figure 3A -F、 Figure 4A -C and Figures 5A-5F (C-)SN (or (C-)SN of CU), or Figure 6A -B、 Figure 7A -B、 Figure 8 and Figure 9 Implemented in the candidate base station or (C-)MN (or (C-)MN's CU)).

[0236] Method 1300A begins at block 1302A, where the first network node configures a first candidate cell for the UE. In block 1304A, the first network node prevents the configuration of a second candidate cell for the UE. Because only one candidate cell is configured for the UE, the second network node, which operates on the candidate cell directly or indirectly via a child node, does not need to manage multiple conditional configurations for the UE.

[0237] Figure 13B The illustration depicts a similar example method 1300B for configuring conditional configurations for a UE and avoiding the need to manage multiple conditional configurations associated with the same network node. This method can be implemented, for example, at a first network node (such as...). Figure 3A -F、 Figure 4A -C and Figures 5A-5F (C-)SN (or (C-)SN of CU), or Figure 6A -B、 Figure 7A -B、 Figure 8 and Figure 9 Implemented in the candidate base station or (C-)MN (or (C-)MN's CU)).

[0238] Method 1300B begins at block 1302B, where the first network node configures a first candidate cell of the second network node for the UE. In block 1304B, the first network node configures a second candidate cell of the second network node for the UE. The second network node may be a DU, which, for example, could be... Figure 3A -F、 Figure 4A -C and Figures 5A-5F , Figure 6A -B、 Figure 7A -B、 Figure 8 and Figure 9 The M-DU, S-DU, or C-DU, (C-)MN, or (C-)SN. The first and second network nodes can be the same or different. Because only one candidate cell is configured for the UE, the second network node that operates the candidate cell directly or indirectly via a sub-node does not need to manage multiple conditional configurations for the UE.

[0239] Unlike method 1300A, the first network node using method 1300B can configure the second candidate cell of the third network node for the UE.

[0240] Figure 14 An example method 1400 is described for configuring conditional base station configurations for a UE and avoiding the need to manage multiple conditional configurations. This method, for example, can be implemented in... Figure 3A -F、 Figure 4A -C、 Figures 5A-5F , Figure 6A -B、 Figure 7A -B、 Figure 8 and Figure 9 Implemented in base stations.

[0241] Method 1400 begins at block 1402, where the base station receives measurement results (one or more) of a cell from the UE. At block 1404, the base station determines whether the measurement results (one or more) satisfy a threshold for conditional configuration. The method terminates if the threshold is not met. Otherwise, the process proceeds to block 1406, where the base station further determines whether the cell belongs to a network node that has already configured a candidate cell for the UE. If the cell does belong to a network node that has already configured a candidate cell for the UE, the process proceeds to block 1410, where the base station does not transmit the conditional configuration of configuring the cell as a candidate cell to the UE. Otherwise, the process proceeds to block 1408, where the base station transmits the conditional configuration of configuring the cell as a candidate cell to the UE.

[0242] Now for reference Figure 15The document describes an example method 1500 for performing conditional mobility and notifying network nodes of candidate cell IDs. This method can be implemented in a UE such as UE 102 discussed above. According to this method, the UE determines whether the conditions for connecting to the candidate cell are met, and then, based on this determination, transmits an RRC response message including the configured cell ID of the candidate cell to the candidate base station. For example, the network node can be an M-CU, S-CU, C-CU, (C-)MN, or (C-)SN.

[0243] Method 1500 begins at block 1502, where the UE receives conditional configuration of the candidate cell. At block 1504, the UE determines that the conditions for connecting to the candidate cell are met. At block 1506, in response to the determination at block 1504, the UE transmits an RRC response message including the cell identifier of the candidate cell (e.g., ...). Figure 3A Event 336A; Figure 4A Event 436A; Figure 5A Event 536A). In box 1508, the UE responds to the determination in box 1504 to connect to the candidate cell.

[0244] Next, Figure 16 The illustration shows a similar example method 1600 for conditional mobility and notifying network nodes of candidate cell IDs, which can be implemented in a UE such as UE 102 discussed above. For example, the network node can be an M-CU, S-CU, C-CU, (C-)MN, or (C-)SN.

[0245] Method 1600 begins at box 1602, where the UE determines to transmit an RRC response message. At box 1604, if the determination at box 1602 is triggered by satisfying conditions for connecting to a candidate cell, the process proceeds to box 1606, where the UE includes the cell identifier of the candidate cell in the RRC response message, and then the UE transmits the RRC response message at box 1608 (e.g., ...). Figure 3A Event 336A; Figure 4A Event 436A; Figure 5A (Event 536A). If the determination at box 1602 is not triggered by the satisfaction of the conditions for connecting to the candidate cell at box 1604, the procedure proceeds directly to box 1608, where the UE transmits an RRC response message.

[0246] Figure 17 The illustration shows another example method 1700 for conditional mobility and notifying network nodes of candidate cell IDs, which can be implemented in a UE such as UE 102 discussed above. For example, the network node can be an M-CU, S-CU, C-CU, (C-)MN, or (C-)SN.

[0247] Method 1700 begins at box 1702, where the UE determines to transmit an RRC response message. At box 1704, if the determination at box 1702 is triggered by satisfying conditions for connecting to the candidate PSCell, the procedure proceeds to box 1706, where the UE determines whether the conditional configuration of the candidate PSCell was received from SRB1 or SRB3. If it is from SRB3, the procedure proceeds to box 1712, where the UE transmits an RRC response message on SRB3. Otherwise, if it is from SRB1, the procedure proceeds to box 1708, where the UE includes the cell identifier of the candidate cell in the RRC response message, and then the UE transmits an RRC message on SRB1 (e.g., ...). Figure 3A Event 336A; Figure 4A Event 436A; Figure 5A (Event 536A). If the determination at box 1702 is not triggered by satisfying the conditions for connecting the candidate PSCell at box 1704, the process proceeds directly to box 1710, where the UE transmits an RRC response message on SRB1.

[0248] Figure 18 The illustration shows another example method 1800 for processing messages with conditional mobility for a UE, which can be used in, for example... Figure 3B , Figure 4B and Figure 5B Implemented in the first network node of (C-)SN (or (C-)SN CU).

[0249] Method 1800 begins at box 1802, where the base station CU transmits conditional configuration of the cell for the UE. Figure 3B Event 320B). At box 1804, the base station CU receives an interface message from the DU including the RRC container and the cell ID for the cell of the UE. Figure 3B Event 344B; Figure 4B Event 444B; Figure 5B Event 544B). At box 1806, the base station CU determines whether the interface message includes an indicator indicating that the RRC container should be ignored. If the interface message includes this indicator, then at box 1808, the base station CU ignores the RRC container. If the interface message does not include this indicator, then at box 1810, the base station CU processes the RRC container, i.e., decodes the RRC message in the RRC container and processes the contents of the RRC message. At box 1812, the base station CU communicates with the UE via the DU on the cell using conditional configuration (…). Figure 3B Event 348B; Figure 4B Event 448B; Figure 5B(Event 548B). In some implementations, the interface message may be a UL RRC message transmission message.

[0250] Figure 19 The illustration shows another example method 1900 for processing messages with conditional mobility for a UE, which can be used in, for example... Figure 3B , Figure 4B and Figure 5B Implemented in the first network node of (C-)SN (or (C-)SN of DU).

[0251] Method 1900 begins at block 1902, where the base station DU performs a random access procedure with the UE via the cell ( Figure 3B Event 342B; Figure 4B Event 442B; Figure 5B Event 542B). At box 1904, the base station DU determines whether the cell is a candidate cell for the UE. If the cell is a candidate cell, at box 1906, the base station DU generates an interface message including the cell ID, the RRC container IE, and an indicator indicating that the RRC container IE should be ignored. If the cell is not a candidate cell, at box 1908, the base station DU generates an interface message including the RRC container IE and excluding an indicator indicating that the RRC container IE should be ignored. At box 1910, the base station DU transmits the interface message to the base station CU (…). Figure 3B Event 344B; Figure 4B Event 444B; Figure 5B Event 544B). In some implementations, the interface message may be a UL RRC message transmission message.

[0252] In some implementations, when the CU performs a UE context setting procedure or a UE context modification procedure to prepare for a conditional PSCell change, the base station DU may store the UE's candidate cell identifier. If the cell ID of the cell is the same as the candidate cell ID, the base station DU may determine that the cell is a candidate cell. Otherwise, the base station DU may determine that the cell is not a candidate cell. In other implementations, the base station DU may store the UE's C-DU configuration. The C-DU configuration includes the UE identifier. If the base station DU receives the UE identifier from the UE on a cell, the base station DU may determine that the cell is a candidate cell for the UE. Otherwise, the base station may determine that the cell is not a candidate cell for the UE.

[0253] The following description can be applied to the description above.

[0254] User equipment (e.g., UE 102) in which the technologies of this disclosure can be implemented can be any suitable device capable of wireless communication, such as a smartphone, tablet computer, laptop computer, mobile game console, point-of-sale (POS) terminal, health monitoring device, drone, camera, media streaming dongle or other personal media device, wearable device (such as a smartwatch), wireless hotspot, femtocell, or broadband router. Furthermore, in some cases, the user equipment can be embedded in an electronic system, such as a head unit in a vehicle or an advanced driver assistance system (ADAS). Further still, the user equipment can operate 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, computer-readable storage, a user interface, one or more network interfaces, one or more sensors, etc.

[0255] In this disclosure, certain embodiments are described as including logic or multiple components or modules. A module can be a software module (e.g., code or machine-readable instructions stored on a non-transitory machine-readable medium) or a hardware module. A hardware module is a tangible unit capable of performing certain operations and can be configured or arranged in a certain way. A hardware module may include dedicated circuitry or logic permanently configured (e.g., as a dedicated processor, such as a field-programmable gate array (FPGA) or application-specific integrated circuit (ASIC), digital signal processor (DSP), etc.) to perform certain operations. A hardware module may also include programmable logic or circuitry (e.g., encompassed within a general-purpose processor or other programmable processor) that is temporarily configured by software to perform certain operations. The decision to implement a hardware module in dedicated and permanently configured circuitry, or in temporarily configured circuitry (e.g., configured by software), may be driven by cost and time considerations.

[0256] When implemented in software, these technologies can be provided as part of an operating system, libraries used by multiple applications, or specific software applications. The software can be executed by one or more general-purpose processors or one or more dedicated processors.

[0257] Upon reading this disclosure, those skilled in the art will understand the additional and alternative structural and functional designs for addressing mobility between base stations using the principles disclosed herein. Therefore, while specific embodiments and applications have been shown and described, it should be understood that the disclosed embodiments are not limited to the precise constructions and components disclosed herein. Various modifications, alterations, and variations can be made to the arrangement, operation, and details of the methods and apparatus disclosed herein without departing from the spirit and scope defined in the appended claims, as will be apparent to those skilled in the art.

[0258] The following list of examples reflects additional embodiments explicitly contemplated by this disclosure.

[0259] Example 1. A method for configuring a connection with a UE in a central unit (CU) of a distributed base station, the method comprising: providing the UE with a conditional configuration of a cell of the distributed unit (DU) of the base station via processing hardware; receiving, via the processing hardware, an identifier of the cell of the DU; determining, via the processing hardware, that the UE is connected to the cell based on the identifier of the cell; and communicating with the UE according to the conditional configuration for the cell.

[0260] Example 2. According to the method of Example 1, wherein the identifier of the cell is a Cell Global Identifier (CGI), and the method further includes: storing a mapping between the CGI and the corresponding Physical Cell Identifier (PCI) through the processing hardware; and determining, through the processing hardware, that the UE is connected to the cell based on the received CGI and the stored mapping.

[0261] Example 3. The method according to any one of the foregoing examples, wherein the identifier of the cell of the DU is received from the DU.

[0262] Example 4. The method according to any one of the foregoing examples, wherein the identifier of the cell of the DU is received from the UE.

[0263] Example 5. The method according to any one of the foregoing examples, wherein the cell is a first cell, the conditional configuration is a first conditional configuration, and the method further includes: providing the UE with a second conditional configuration for a second cell of the DU via processing hardware; and determining, via the processing hardware, that the UE has selected the first conditional configuration based on the identifier of the first cell.

[0264] Example 6. The method according to any one of the foregoing examples, wherein the identifier of the cell receiving the DU includes: receiving a status message or F1 application protocol (AP) message from the DU including the identifier of the cell of the DU via the processing hardware.

[0265] Example 7. The method according to any of the preceding examples, wherein the identifier is a tunnel endpoint identifier (TEID).

[0266] Example 8. A method according to any one of the foregoing examples, wherein the cell is a first cell, the conditional configuration is a first conditional configuration, providing the first conditional configuration for the first cell of the DU includes providing a first TEID, and the method further includes: providing the UE with a second conditional configuration for a second cell of the DU via processing hardware, the second conditional configuration including a second TEID; wherein: receiving the status message includes receiving the status message with the first TEID via the processing hardware, and determining that the UE is connected to the first cell includes determining that the UE is connected to the first cell via the processing hardware based on receiving the first TEID.

[0267] Example 9. The method according to any one of the foregoing examples further includes: storing one or more associations between a specific TEID and a specific conditional configuration through the processing hardware; and determining, through the processing hardware, the specific conditional configuration selected by the UE based on the stored one or more associations and the received TEID.

[0268] Example 10. The method according to any one of the preceding examples, wherein: providing the first conditional configuration for the first cell of the DU further includes obtaining a first TEID through the processing hardware; and providing the second conditional configuration for the second cell of the DU further includes obtaining a second TEID through the processing hardware.

[0269] Example 11. A method for configuring a connection with a UE in a central unit (CU) of a distributed base station, the method comprising: receiving the measurement results from the UE via processing hardware; determining, based on the measurement results, that conditions for initiating conditional configuration for a cell of the distributed unit (DU) of the base station have been met by the processing hardware; generating, via the processing hardware, the conditional configuration for the cell of the DU in response to determining that the conditions have been met; providing, via the processing hardware, the conditional configuration for the cell of the DU to the UE; and preventing additional conditional configuration for additional cells of the DU.

[0270] Example 12. The method according to Example 11 further includes: receiving additional measurement results from the UE via the processing hardware; determining, based on the measurement results, that conditions for initiating additional conditional configuration for the additional cell have been met via the processing hardware; determining, via the processing hardware, whether the additional cell belongs to the DU; and preventing the generation of the additional conditional configuration in response to determining that the additional cell belongs to the DU.

[0271] Example 13. The method according to any one of Example 11 or Example 12 further includes: in response to determining that the additional cell does not belong to the DU, generating the additional conditional configuration through the processing hardware.

[0272] Example 14. A method for configuring a connection with a UE in a distributed unit (DU) of a distributed base station, the method comprising: receiving, via processing hardware, a request message from a central unit (CU) of the base station for obtaining a conditional configuration for connecting to a cell of the DU; providing the conditional configuration for the cell to the CU via the processing hardware; performing a random access procedure with the UE via the processing hardware to connect the UE to the cell; and providing the CU via the processing hardware an identifier of the cell of the DU to indicate to the CU that the UE is connected to the cell corresponding to the conditional configuration.

[0273] Example 15. The method according to Example 14, wherein the identifier of the cell is a Cell Global Identifier (CGI).

[0274] Example 16. The method according to Example 14 or Example 15, wherein providing the identifier of the cell includes: providing the CU to the CU via the processing hardware with a CU-DU interface message including the identifier of the cell.

[0275] Example 17. The method according to any one of Examples 14-16, wherein the CU to DU interface message is an F1 application protocol (AP) message.

[0276] Example 18. The method according to any one of Examples 14-17, wherein the F1 AP message does not include a Radio Resource Control (RRC) message.

[0277] Example 19. A method according to any one of Examples 14-18, wherein the cell is a first cell, the conditional configuration is a first conditional configuration, and the method further comprises: providing the CU with a second conditional configuration for a second cell of the DU via processing hardware; and in response to performing the random access procedure with the UE to connect the UE to the first cell, providing the CU with an identifier of the first cell of the DU via the processing hardware to indicate to the CU that the UE is connected to the first cell corresponding to the first conditional configuration.

[0278] Example 20. The method according to any one of the preceding examples, wherein the distributed base station is a node in a radio access network (RAN) operating in multiple radio dual connectivity (MR-DC), and wherein the first conditional configuration and the second conditional configuration are provided for candidate primary and secondary cells (C-PSCells) of the SN during a conditional PSCell Add or Change (CPAC) configuration process.

[0279] Example 21. The method according to any one of the preceding examples, wherein the distributed base station is a node in a radio access network (RAN) operating in multiple radio dual connectivity (MR-DC), and wherein the first conditional configuration and the second conditional configuration are provided for candidate secondary nodes (C-SNs) in a conditional SN addition or change (CSAC) configuration process.

[0280] Example 22. The method according to any one of the foregoing examples, wherein the distributed base station includes a first DU operating as a primary DU in the MR-DC and a second DU operating as a secondary DU in the MR-DC.

[0281] Example 23. The method according to any one of the foregoing examples, wherein the distributed base station is a node in a radio access network (RAN) operating in single connectivity (SC), and wherein the first conditional configuration and the second conditional configuration are provided for a conditional handover (CHO) procedure.

[0282] Example 24. The method according to any one of the preceding examples, wherein the distributed base station includes a first DU operating as a source DU and a second DU operating as a candidate DU in the SC.

[0283] Example 25. A base station including processing hardware and configured to implement the method according to any one of the foregoing examples.

[0284] Example 26. A method in a UE for configuring a connection with a distributed element (DU) of a base station, the method comprising: receiving, via processing hardware, a first conditional configuration for a first cell of the DU of the base station from a central element (CU) of the base station; receiving, via the processing hardware, a second conditional configuration for a second cell of the DU from the CU; in response to determining that a condition of the second conditional configuration is satisfied, selecting, via the processing hardware, the second conditional configuration; and in response to the selection, connecting, via the processing hardware, to the second cell of the DU.

[0285] Example 27. The method according to Example 26 further includes: transmitting a radio connection reconfiguration complete message including the identifier of the second cell of the DU via the processing hardware.

[0286] Example 28. The method according to any one of Example 26 or Example 27 further includes: transmitting, via the processing hardware, a radio connection reconfiguration completion message including a UE identifier for identifying the selected conditional configuration, wherein the radio connection reconfiguration completion message does not include the identifier of the second cell of the DU.

[0287] Example 29. The method according to any one of Examples 26-28, wherein: receiving the first conditional configuration for the first cell of the DU further includes receiving a first UE identifier through the processing hardware; receiving the second conditional configuration for the second cell of the DU further includes receiving a second UE identifier through the processing hardware; wherein the processing hardware transmits the radio connection reconfiguration complete message with the second UE identifier.

[0288] Example 30. The method according to any one of Examples 26-29, wherein transmitting the radio connection reconfiguration complete message includes transmitting a radio connection reconfiguration complete message including a radio network temporary identifier (RNTI) through the processing hardware.

[0289] Example 31. The method according to any one of Examples 25-30, further comprising: transmitting a radio connection reconfiguration message through the processing hardware, wherein the radio connection reconfiguration completion message does not include the identifier of the second cell of the DU.

[0290] Example 32. The method according to any one of Examples 26-31, wherein the UE operates in multiple radio dual connectivity (MR-DC), and wherein the first conditional configuration and the second conditional configuration are provided for candidate primary and secondary cells (C-PSCells) of the SN during a conditional PSCell Add or Change (CPAC) configuration process.

[0291] Example 33. The method according to any one of Examples 26-32, wherein the UE operates in multiple radio dual connectivity (MR-DC), and wherein the first conditional configuration and the second conditional configuration are provided for candidate secondary nodes (C-SNs) in a conditional SN addition or change (CSAC) configuration process.

[0292] Example 34. The method according to any one of Examples 26-33, wherein the UE operates in single connectivity (SC), and wherein the first conditional configuration and the second conditional configuration are provided for a conditional handover (CHO) procedure.

[0293] Example 35. A user equipment (UE) includes processing hardware and is configured to implement the method according to any one of Examples 26-34.

Claims

1. A method for configuring a connection with a UE, performed by a central unit (CU) of a distributed base station of a radio access network (RAN), the method comprising: The CU provides the UE with a first conditional configuration to be applied to enable the UE to communicate with the RAN via a first cell of the distributed unit (DU) of the distributed base station when a first condition is met, and a second conditional configuration to be applied to enable the UE to communicate with the RAN via a second cell of the DU when a second condition is met; The CU receives the identifier of the first cell of the DU; Based on the identifier of the first cell, the CU determines that the UE is connected to the first cell; as well as The CU communicates with the UE via the DU according to the first conditional configuration for the first cell.

2. The method according to claim 1, wherein, The identifier of the first cell is the Cell Global Identifier (CGI).

3. The method according to claim 2, further comprising: The CU stores the mapping between CGI and the corresponding Physical Cell Identifier (PCI); as well as Based on the received CGI and the stored mapping, the CU determines that the UE is connected to the first cell.

4. The method according to claim 1, wherein, The identifier of the first cell of the DU is received from the DU.

5. The method according to claim 1, wherein, The identifier of the first cell of the DU is received from the UE.

6. The method according to claim 1, wherein, The identifier of the first cell receiving the DU includes: The CU receives a status message or F1 Application Protocol (AP) message from the DU, which includes the identifier of the first cell of the DU.

7. The method according to claim 1 or 6, wherein, The identifier is the Tunnel Endpoint Identifier (TEID).

8. The method according to claim 7, wherein, Providing the first conditional configuration for the first cell of the DU includes providing a first TEID. Providing the second conditional configuration for the second cell of the DU includes providing a second TEID, and When the status message includes the first TEID, the CU determines that the UE is connected to the first cell.

9. The method of claim 8, further comprising: The CU stores one or more associations between one or more TEIDs and one or more conditional configurations; as well as Based on one or more stored associations and the received TEID from the one or more TEIDs, the CU determines that the UE uses a specific conditional configuration from the one or more conditional configurations.

10. A method for configuring a connection with a UE, performed by a distributed unit (DU) of a distributed base station of a radio access network (RAN), the method comprising: The DU receives a request message from the central unit CU of the distributed base station. The request message is used to obtain a first conditional configuration to be applied to connect the UE to the first cell of the DU when a first condition is met. The DU provides the CU with the first conditional configuration for the first cell; The DU provides the CU with a second conditional configuration to be applied to connect the UE to the second cell of the DU when the second condition is met; The DU and UE perform a random access procedure to connect the UE to the first cell; as well as The DU provides the CU with the identifier of the first cell of the DU to indicate to the CU that the UE is connected to the first cell corresponding to the first conditional configuration.

11. The method according to claim 10, wherein, The identifier of the first cell is the Cell Global Identifier (CGI).

12. The method according to claim 10, wherein, The identifier provided for the first cell includes: The DU provides the CU with a DU-CU interface message including the identifier of the first cell.

13. The method according to claim 12, wherein, The DU to CU interface message is an F1 application protocol (AP) message.

14. A distributed base station, comprising processing hardware for a central unit (CU) and distributed units (DU) and a radio access network (RAN) communication interface, and configured to implement the method according to any one of the preceding claims.

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